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134 | .IX Title "LIBEV 3" |
135 | .IX Title "LIBEV 3" |
135 | .TH LIBEV 3 "2009-04-25" "libev-3.6" "libev - high performance full featured event loop" |
136 | .TH LIBEV 3 "2014-09-05" "libev-4.15" "libev - high performance full featured event loop" |
136 | .\" For nroff, turn off justification. Always turn off hyphenation; it makes |
137 | .\" For nroff, turn off justification. Always turn off hyphenation; it makes |
137 | .\" way too many mistakes in technical documents. |
138 | .\" way too many mistakes in technical documents. |
138 | .if n .ad l |
139 | .if n .ad l |
139 | .nh |
140 | .nh |
140 | .SH "NAME" |
141 | .SH "NAME" |
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142 | .SH "SYNOPSIS" |
143 | .SH "SYNOPSIS" |
143 | .IX Header "SYNOPSIS" |
144 | .IX Header "SYNOPSIS" |
144 | .Vb 1 |
145 | .Vb 1 |
145 | \& #include <ev.h> |
146 | \& #include <ev.h> |
146 | .Ve |
147 | .Ve |
147 | .Sh "\s-1EXAMPLE\s0 \s-1PROGRAM\s0" |
148 | .SS "\s-1EXAMPLE PROGRAM\s0" |
148 | .IX Subsection "EXAMPLE PROGRAM" |
149 | .IX Subsection "EXAMPLE PROGRAM" |
149 | .Vb 2 |
150 | .Vb 2 |
150 | \& // a single header file is required |
151 | \& // a single header file is required |
151 | \& #include <ev.h> |
152 | \& #include <ev.h> |
152 | \& |
153 | \& |
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165 | \& puts ("stdin ready"); |
166 | \& puts ("stdin ready"); |
166 | \& // for one\-shot events, one must manually stop the watcher |
167 | \& // for one\-shot events, one must manually stop the watcher |
167 | \& // with its corresponding stop function. |
168 | \& // with its corresponding stop function. |
168 | \& ev_io_stop (EV_A_ w); |
169 | \& ev_io_stop (EV_A_ w); |
169 | \& |
170 | \& |
170 | \& // this causes all nested ev_loop\*(Aqs to stop iterating |
171 | \& // this causes all nested ev_run\*(Aqs to stop iterating |
171 | \& ev_unloop (EV_A_ EVUNLOOP_ALL); |
172 | \& ev_break (EV_A_ EVBREAK_ALL); |
172 | \& } |
173 | \& } |
173 | \& |
174 | \& |
174 | \& // another callback, this time for a time\-out |
175 | \& // another callback, this time for a time\-out |
175 | \& static void |
176 | \& static void |
176 | \& timeout_cb (EV_P_ ev_timer *w, int revents) |
177 | \& timeout_cb (EV_P_ ev_timer *w, int revents) |
177 | \& { |
178 | \& { |
178 | \& puts ("timeout"); |
179 | \& puts ("timeout"); |
179 | \& // this causes the innermost ev_loop to stop iterating |
180 | \& // this causes the innermost ev_run to stop iterating |
180 | \& ev_unloop (EV_A_ EVUNLOOP_ONE); |
181 | \& ev_break (EV_A_ EVBREAK_ONE); |
181 | \& } |
182 | \& } |
182 | \& |
183 | \& |
183 | \& int |
184 | \& int |
184 | \& main (void) |
185 | \& main (void) |
185 | \& { |
186 | \& { |
186 | \& // use the default event loop unless you have special needs |
187 | \& // use the default event loop unless you have special needs |
187 | \& struct ev_loop *loop = ev_default_loop (0); |
188 | \& struct ev_loop *loop = EV_DEFAULT; |
188 | \& |
189 | \& |
189 | \& // initialise an io watcher, then start it |
190 | \& // initialise an io watcher, then start it |
190 | \& // this one will watch for stdin to become readable |
191 | \& // this one will watch for stdin to become readable |
191 | \& ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ); |
192 | \& ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ); |
192 | \& ev_io_start (loop, &stdin_watcher); |
193 | \& ev_io_start (loop, &stdin_watcher); |
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195 | \& // simple non\-repeating 5.5 second timeout |
196 | \& // simple non\-repeating 5.5 second timeout |
196 | \& ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.); |
197 | \& ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.); |
197 | \& ev_timer_start (loop, &timeout_watcher); |
198 | \& ev_timer_start (loop, &timeout_watcher); |
198 | \& |
199 | \& |
199 | \& // now wait for events to arrive |
200 | \& // now wait for events to arrive |
200 | \& ev_loop (loop, 0); |
201 | \& ev_run (loop, 0); |
201 | \& |
202 | \& |
202 | \& // unloop was called, so exit |
203 | \& // break was called, so exit |
203 | \& return 0; |
204 | \& return 0; |
204 | \& } |
205 | \& } |
205 | .Ve |
206 | .Ve |
206 | .SH "ABOUT THIS DOCUMENT" |
207 | .SH "ABOUT THIS DOCUMENT" |
207 | .IX Header "ABOUT THIS DOCUMENT" |
208 | .IX Header "ABOUT THIS DOCUMENT" |
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214 | While this document tries to be as complete as possible in documenting |
215 | While this document tries to be as complete as possible in documenting |
215 | libev, its usage and the rationale behind its design, it is not a tutorial |
216 | libev, its usage and the rationale behind its design, it is not a tutorial |
216 | on event-based programming, nor will it introduce event-based programming |
217 | on event-based programming, nor will it introduce event-based programming |
217 | with libev. |
218 | with libev. |
218 | .PP |
219 | .PP |
219 | Familarity with event based programming techniques in general is assumed |
220 | Familiarity with event based programming techniques in general is assumed |
220 | throughout this document. |
221 | throughout this document. |
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222 | .SH "WHAT TO READ WHEN IN A HURRY" |
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223 | .IX Header "WHAT TO READ WHEN IN A HURRY" |
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224 | This manual tries to be very detailed, but unfortunately, this also makes |
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225 | it very long. If you just want to know the basics of libev, I suggest |
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226 | reading \*(L"\s-1ANATOMY OF A WATCHER\*(R"\s0, then the \*(L"\s-1EXAMPLE PROGRAM\*(R"\s0 above and |
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227 | look up the missing functions in \*(L"\s-1GLOBAL FUNCTIONS\*(R"\s0 and the \f(CW\*(C`ev_io\*(C'\fR and |
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228 | \&\f(CW\*(C`ev_timer\*(C'\fR sections in \*(L"\s-1WATCHER TYPES\*(R"\s0. |
221 | .SH "ABOUT LIBEV" |
229 | .SH "ABOUT LIBEV" |
222 | .IX Header "ABOUT LIBEV" |
230 | .IX Header "ABOUT LIBEV" |
223 | Libev is an event loop: you register interest in certain events (such as a |
231 | Libev is an event loop: you register interest in certain events (such as a |
224 | file descriptor being readable or a timeout occurring), and it will manage |
232 | file descriptor being readable or a timeout occurring), and it will manage |
225 | these event sources and provide your program with events. |
233 | these event sources and provide your program with events. |
… | |
… | |
230 | .PP |
238 | .PP |
231 | You register interest in certain events by registering so-called \fIevent |
239 | You register interest in certain events by registering so-called \fIevent |
232 | watchers\fR, which are relatively small C structures you initialise with the |
240 | watchers\fR, which are relatively small C structures you initialise with the |
233 | details of the event, and then hand it over to libev by \fIstarting\fR the |
241 | details of the event, and then hand it over to libev by \fIstarting\fR the |
234 | watcher. |
242 | watcher. |
235 | .Sh "\s-1FEATURES\s0" |
243 | .SS "\s-1FEATURES\s0" |
236 | .IX Subsection "FEATURES" |
244 | .IX Subsection "FEATURES" |
237 | Libev supports \f(CW\*(C`select\*(C'\fR, \f(CW\*(C`poll\*(C'\fR, the Linux-specific \f(CW\*(C`epoll\*(C'\fR, the |
245 | Libev supports \f(CW\*(C`select\*(C'\fR, \f(CW\*(C`poll\*(C'\fR, the Linux-specific \f(CW\*(C`epoll\*(C'\fR, the |
238 | BSD-specific \f(CW\*(C`kqueue\*(C'\fR and the Solaris-specific event port mechanisms |
246 | BSD-specific \f(CW\*(C`kqueue\*(C'\fR and the Solaris-specific event port mechanisms |
239 | for file descriptor events (\f(CW\*(C`ev_io\*(C'\fR), the Linux \f(CW\*(C`inotify\*(C'\fR interface |
247 | for file descriptor events (\f(CW\*(C`ev_io\*(C'\fR), the Linux \f(CW\*(C`inotify\*(C'\fR interface |
240 | (for \f(CW\*(C`ev_stat\*(C'\fR), relative timers (\f(CW\*(C`ev_timer\*(C'\fR), absolute timers |
248 | (for \f(CW\*(C`ev_stat\*(C'\fR), Linux eventfd/signalfd (for faster and cleaner |
241 | with customised rescheduling (\f(CW\*(C`ev_periodic\*(C'\fR), synchronous signals |
249 | inter-thread wakeup (\f(CW\*(C`ev_async\*(C'\fR)/signal handling (\f(CW\*(C`ev_signal\*(C'\fR)) relative |
242 | (\f(CW\*(C`ev_signal\*(C'\fR), process status change events (\f(CW\*(C`ev_child\*(C'\fR), and event |
250 | timers (\f(CW\*(C`ev_timer\*(C'\fR), absolute timers with customised rescheduling |
243 | watchers dealing with the event loop mechanism itself (\f(CW\*(C`ev_idle\*(C'\fR, |
251 | (\f(CW\*(C`ev_periodic\*(C'\fR), synchronous signals (\f(CW\*(C`ev_signal\*(C'\fR), process status |
244 | \&\f(CW\*(C`ev_embed\*(C'\fR, \f(CW\*(C`ev_prepare\*(C'\fR and \f(CW\*(C`ev_check\*(C'\fR watchers) as well as |
252 | change events (\f(CW\*(C`ev_child\*(C'\fR), and event watchers dealing with the event |
245 | file watchers (\f(CW\*(C`ev_stat\*(C'\fR) and even limited support for fork events |
253 | loop mechanism itself (\f(CW\*(C`ev_idle\*(C'\fR, \f(CW\*(C`ev_embed\*(C'\fR, \f(CW\*(C`ev_prepare\*(C'\fR and |
246 | (\f(CW\*(C`ev_fork\*(C'\fR). |
254 | \&\f(CW\*(C`ev_check\*(C'\fR watchers) as well as file watchers (\f(CW\*(C`ev_stat\*(C'\fR) and even |
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255 | limited support for fork events (\f(CW\*(C`ev_fork\*(C'\fR). |
247 | .PP |
256 | .PP |
248 | It also is quite fast (see this |
257 | It also is quite fast (see this |
249 | benchmark comparing it to libevent |
258 | benchmark <http://libev.schmorp.de/bench.html> comparing it to libevent |
250 | for example). |
259 | for example). |
251 | .Sh "\s-1CONVENTIONS\s0" |
260 | .SS "\s-1CONVENTIONS\s0" |
252 | .IX Subsection "CONVENTIONS" |
261 | .IX Subsection "CONVENTIONS" |
253 | Libev is very configurable. In this manual the default (and most common) |
262 | Libev is very configurable. In this manual the default (and most common) |
254 | configuration will be described, which supports multiple event loops. For |
263 | configuration will be described, which supports multiple event loops. For |
255 | more info about various configuration options please have a look at |
264 | more info about various configuration options please have a look at |
256 | \&\fB\s-1EMBED\s0\fR section in this manual. If libev was configured without support |
265 | \&\fB\s-1EMBED\s0\fR section in this manual. If libev was configured without support |
257 | for multiple event loops, then all functions taking an initial argument of |
266 | for multiple event loops, then all functions taking an initial argument of |
258 | name \f(CW\*(C`loop\*(C'\fR (which is always of type \f(CW\*(C`ev_loop *\*(C'\fR) will not have |
267 | name \f(CW\*(C`loop\*(C'\fR (which is always of type \f(CW\*(C`struct ev_loop *\*(C'\fR) will not have |
259 | this argument. |
268 | this argument. |
260 | .Sh "\s-1TIME\s0 \s-1REPRESENTATION\s0" |
269 | .SS "\s-1TIME REPRESENTATION\s0" |
261 | .IX Subsection "TIME REPRESENTATION" |
270 | .IX Subsection "TIME REPRESENTATION" |
262 | Libev represents time as a single floating point number, representing |
271 | Libev represents time as a single floating point number, representing |
263 | the (fractional) number of seconds since the (\s-1POSIX\s0) epoch (somewhere |
272 | the (fractional) number of seconds since the (\s-1POSIX\s0) epoch (in practice |
264 | near the beginning of 1970, details are complicated, don't ask). This |
273 | somewhere near the beginning of 1970, details are complicated, don't |
265 | type is called \f(CW\*(C`ev_tstamp\*(C'\fR, which is what you should use too. It usually |
274 | ask). This type is called \f(CW\*(C`ev_tstamp\*(C'\fR, which is what you should use |
266 | aliases to the \f(CW\*(C`double\*(C'\fR type in C. When you need to do any calculations |
275 | too. It usually aliases to the \f(CW\*(C`double\*(C'\fR type in C. When you need to do |
267 | on it, you should treat it as some floating point value. Unlike the name |
276 | any calculations on it, you should treat it as some floating point value. |
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277 | .PP |
268 | component \f(CW\*(C`stamp\*(C'\fR might indicate, it is also used for time differences |
278 | Unlike the name component \f(CW\*(C`stamp\*(C'\fR might indicate, it is also used for |
269 | throughout libev. |
279 | time differences (e.g. delays) throughout libev. |
270 | .SH "ERROR HANDLING" |
280 | .SH "ERROR HANDLING" |
271 | .IX Header "ERROR HANDLING" |
281 | .IX Header "ERROR HANDLING" |
272 | Libev knows three classes of errors: operating system errors, usage errors |
282 | Libev knows three classes of errors: operating system errors, usage errors |
273 | and internal errors (bugs). |
283 | and internal errors (bugs). |
274 | .PP |
284 | .PP |
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292 | library in any way. |
302 | library in any way. |
293 | .IP "ev_tstamp ev_time ()" 4 |
303 | .IP "ev_tstamp ev_time ()" 4 |
294 | .IX Item "ev_tstamp ev_time ()" |
304 | .IX Item "ev_tstamp ev_time ()" |
295 | Returns the current time as libev would use it. Please note that the |
305 | Returns the current time as libev would use it. Please note that the |
296 | \&\f(CW\*(C`ev_now\*(C'\fR function is usually faster and also often returns the timestamp |
306 | \&\f(CW\*(C`ev_now\*(C'\fR function is usually faster and also often returns the timestamp |
297 | you actually want to know. |
307 | you actually want to know. Also interesting is the combination of |
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308 | \&\f(CW\*(C`ev_now_update\*(C'\fR and \f(CW\*(C`ev_now\*(C'\fR. |
298 | .IP "ev_sleep (ev_tstamp interval)" 4 |
309 | .IP "ev_sleep (ev_tstamp interval)" 4 |
299 | .IX Item "ev_sleep (ev_tstamp interval)" |
310 | .IX Item "ev_sleep (ev_tstamp interval)" |
300 | Sleep for the given interval: The current thread will be blocked until |
311 | Sleep for the given interval: The current thread will be blocked |
301 | either it is interrupted or the given time interval has passed. Basically |
312 | until either it is interrupted or the given time interval has |
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313 | passed (approximately \- it might return a bit earlier even if not |
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314 | interrupted). Returns immediately if \f(CW\*(C`interval <= 0\*(C'\fR. |
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315 | .Sp |
302 | this is a sub-second-resolution \f(CW\*(C`sleep ()\*(C'\fR. |
316 | Basically this is a sub-second-resolution \f(CW\*(C`sleep ()\*(C'\fR. |
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317 | .Sp |
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318 | The range of the \f(CW\*(C`interval\*(C'\fR is limited \- libev only guarantees to work |
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319 | with sleep times of up to one day (\f(CW\*(C`interval <= 86400\*(C'\fR). |
303 | .IP "int ev_version_major ()" 4 |
320 | .IP "int ev_version_major ()" 4 |
304 | .IX Item "int ev_version_major ()" |
321 | .IX Item "int ev_version_major ()" |
305 | .PD 0 |
322 | .PD 0 |
306 | .IP "int ev_version_minor ()" 4 |
323 | .IP "int ev_version_minor ()" 4 |
307 | .IX Item "int ev_version_minor ()" |
324 | .IX Item "int ev_version_minor ()" |
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319 | as this indicates an incompatible change. Minor versions are usually |
336 | as this indicates an incompatible change. Minor versions are usually |
320 | compatible to older versions, so a larger minor version alone is usually |
337 | compatible to older versions, so a larger minor version alone is usually |
321 | not a problem. |
338 | not a problem. |
322 | .Sp |
339 | .Sp |
323 | Example: Make sure we haven't accidentally been linked against the wrong |
340 | Example: Make sure we haven't accidentally been linked against the wrong |
324 | version. |
341 | version (note, however, that this will not detect other \s-1ABI\s0 mismatches, |
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342 | such as \s-1LFS\s0 or reentrancy). |
325 | .Sp |
343 | .Sp |
326 | .Vb 3 |
344 | .Vb 3 |
327 | \& assert (("libev version mismatch", |
345 | \& assert (("libev version mismatch", |
328 | \& ev_version_major () == EV_VERSION_MAJOR |
346 | \& ev_version_major () == EV_VERSION_MAJOR |
329 | \& && ev_version_minor () >= EV_VERSION_MINOR)); |
347 | \& && ev_version_minor () >= EV_VERSION_MINOR)); |
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342 | \& assert (("sorry, no epoll, no sex", |
360 | \& assert (("sorry, no epoll, no sex", |
343 | \& ev_supported_backends () & EVBACKEND_EPOLL)); |
361 | \& ev_supported_backends () & EVBACKEND_EPOLL)); |
344 | .Ve |
362 | .Ve |
345 | .IP "unsigned int ev_recommended_backends ()" 4 |
363 | .IP "unsigned int ev_recommended_backends ()" 4 |
346 | .IX Item "unsigned int ev_recommended_backends ()" |
364 | .IX Item "unsigned int ev_recommended_backends ()" |
347 | Return the set of all backends compiled into this binary of libev and also |
365 | Return the set of all backends compiled into this binary of libev and |
348 | recommended for this platform. This set is often smaller than the one |
366 | also recommended for this platform, meaning it will work for most file |
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367 | descriptor types. This set is often smaller than the one returned by |
349 | returned by \f(CW\*(C`ev_supported_backends\*(C'\fR, as for example kqueue is broken on |
368 | \&\f(CW\*(C`ev_supported_backends\*(C'\fR, as for example kqueue is broken on most BSDs |
350 | most BSDs and will not be auto-detected unless you explicitly request it |
369 | and will not be auto-detected unless you explicitly request it (assuming |
351 | (assuming you know what you are doing). This is the set of backends that |
370 | you know what you are doing). This is the set of backends that libev will |
352 | libev will probe for if you specify no backends explicitly. |
371 | probe for if you specify no backends explicitly. |
353 | .IP "unsigned int ev_embeddable_backends ()" 4 |
372 | .IP "unsigned int ev_embeddable_backends ()" 4 |
354 | .IX Item "unsigned int ev_embeddable_backends ()" |
373 | .IX Item "unsigned int ev_embeddable_backends ()" |
355 | Returns the set of backends that are embeddable in other event loops. This |
374 | Returns the set of backends that are embeddable in other event loops. This |
356 | is the theoretical, all-platform, value. To find which backends |
375 | value is platform-specific but can include backends not available on the |
357 | might be supported on the current system, you would need to look at |
376 | current system. To find which embeddable backends might be supported on |
358 | \&\f(CW\*(C`ev_embeddable_backends () & ev_supported_backends ()\*(C'\fR, likewise for |
377 | the current system, you would need to look at \f(CW\*(C`ev_embeddable_backends () |
359 | recommended ones. |
378 | & ev_supported_backends ()\*(C'\fR, likewise for recommended ones. |
360 | .Sp |
379 | .Sp |
361 | See the description of \f(CW\*(C`ev_embed\*(C'\fR watchers for more info. |
380 | See the description of \f(CW\*(C`ev_embed\*(C'\fR watchers for more info. |
362 | .IP "ev_set_allocator (void *(*cb)(void *ptr, long size)) [\s-1NOT\s0 \s-1REENTRANT\s0]" 4 |
381 | .IP "ev_set_allocator (void *(*cb)(void *ptr, long size) throw ())" 4 |
363 | .IX Item "ev_set_allocator (void *(*cb)(void *ptr, long size)) [NOT REENTRANT]" |
382 | .IX Item "ev_set_allocator (void *(*cb)(void *ptr, long size) throw ())" |
364 | Sets the allocation function to use (the prototype is similar \- the |
383 | Sets the allocation function to use (the prototype is similar \- the |
365 | semantics are identical to the \f(CW\*(C`realloc\*(C'\fR C89/SuS/POSIX function). It is |
384 | semantics are identical to the \f(CW\*(C`realloc\*(C'\fR C89/SuS/POSIX function). It is |
366 | used to allocate and free memory (no surprises here). If it returns zero |
385 | used to allocate and free memory (no surprises here). If it returns zero |
367 | when memory needs to be allocated (\f(CW\*(C`size != 0\*(C'\fR), the library might abort |
386 | when memory needs to be allocated (\f(CW\*(C`size != 0\*(C'\fR), the library might abort |
368 | or take some potentially destructive action. |
387 | or take some potentially destructive action. |
… | |
… | |
394 | \& } |
413 | \& } |
395 | \& |
414 | \& |
396 | \& ... |
415 | \& ... |
397 | \& ev_set_allocator (persistent_realloc); |
416 | \& ev_set_allocator (persistent_realloc); |
398 | .Ve |
417 | .Ve |
399 | .IP "ev_set_syserr_cb (void (*cb)(const char *msg)); [\s-1NOT\s0 \s-1REENTRANT\s0]" 4 |
418 | .IP "ev_set_syserr_cb (void (*cb)(const char *msg) throw ())" 4 |
400 | .IX Item "ev_set_syserr_cb (void (*cb)(const char *msg)); [NOT REENTRANT]" |
419 | .IX Item "ev_set_syserr_cb (void (*cb)(const char *msg) throw ())" |
401 | Set the callback function to call on a retryable system call error (such |
420 | Set the callback function to call on a retryable system call error (such |
402 | as failed select, poll, epoll_wait). The message is a printable string |
421 | as failed select, poll, epoll_wait). The message is a printable string |
403 | indicating the system call or subsystem causing the problem. If this |
422 | indicating the system call or subsystem causing the problem. If this |
404 | callback is set, then libev will expect it to remedy the situation, no |
423 | callback is set, then libev will expect it to remedy the situation, no |
405 | matter what, when it returns. That is, libev will generally retry the |
424 | matter what, when it returns. That is, libev will generally retry the |
… | |
… | |
417 | \& } |
436 | \& } |
418 | \& |
437 | \& |
419 | \& ... |
438 | \& ... |
420 | \& ev_set_syserr_cb (fatal_error); |
439 | \& ev_set_syserr_cb (fatal_error); |
421 | .Ve |
440 | .Ve |
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441 | .IP "ev_feed_signal (int signum)" 4 |
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|
442 | .IX Item "ev_feed_signal (int signum)" |
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443 | This function can be used to \*(L"simulate\*(R" a signal receive. It is completely |
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444 | safe to call this function at any time, from any context, including signal |
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445 | handlers or random threads. |
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446 | .Sp |
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447 | Its main use is to customise signal handling in your process, especially |
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448 | in the presence of threads. For example, you could block signals |
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449 | by default in all threads (and specifying \f(CW\*(C`EVFLAG_NOSIGMASK\*(C'\fR when |
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450 | creating any loops), and in one thread, use \f(CW\*(C`sigwait\*(C'\fR or any other |
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451 | mechanism to wait for signals, then \*(L"deliver\*(R" them to libev by calling |
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452 | \&\f(CW\*(C`ev_feed_signal\*(C'\fR. |
422 | .SH "FUNCTIONS CONTROLLING THE EVENT LOOP" |
453 | .SH "FUNCTIONS CONTROLLING EVENT LOOPS" |
423 | .IX Header "FUNCTIONS CONTROLLING THE EVENT LOOP" |
454 | .IX Header "FUNCTIONS CONTROLLING EVENT LOOPS" |
424 | An event loop is described by a \f(CW\*(C`struct ev_loop *\*(C'\fR (the \f(CW\*(C`struct\*(C'\fR |
455 | An event loop is described by a \f(CW\*(C`struct ev_loop *\*(C'\fR (the \f(CW\*(C`struct\*(C'\fR is |
425 | is \fInot\fR optional in this case, as there is also an \f(CW\*(C`ev_loop\*(C'\fR |
456 | \&\fInot\fR optional in this case unless libev 3 compatibility is disabled, as |
426 | \&\fIfunction\fR). |
457 | libev 3 had an \f(CW\*(C`ev_loop\*(C'\fR function colliding with the struct name). |
427 | .PP |
458 | .PP |
428 | The library knows two types of such loops, the \fIdefault\fR loop, which |
459 | The library knows two types of such loops, the \fIdefault\fR loop, which |
429 | supports signals and child events, and dynamically created loops which do |
460 | supports child process events, and dynamically created event loops which |
430 | not. |
461 | do not. |
431 | .IP "struct ev_loop *ev_default_loop (unsigned int flags)" 4 |
462 | .IP "struct ev_loop *ev_default_loop (unsigned int flags)" 4 |
432 | .IX Item "struct ev_loop *ev_default_loop (unsigned int flags)" |
463 | .IX Item "struct ev_loop *ev_default_loop (unsigned int flags)" |
433 | This will initialise the default event loop if it hasn't been initialised |
464 | This returns the \*(L"default\*(R" event loop object, which is what you should |
434 | yet and return it. If the default loop could not be initialised, returns |
465 | normally use when you just need \*(L"the event loop\*(R". Event loop objects and |
435 | false. If it already was initialised it simply returns it (and ignores the |
466 | the \f(CW\*(C`flags\*(C'\fR parameter are described in more detail in the entry for |
436 | flags. If that is troubling you, check \f(CW\*(C`ev_backend ()\*(C'\fR afterwards). |
467 | \&\f(CW\*(C`ev_loop_new\*(C'\fR. |
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468 | .Sp |
|
|
469 | If the default loop is already initialised then this function simply |
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470 | returns it (and ignores the flags. If that is troubling you, check |
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471 | \&\f(CW\*(C`ev_backend ()\*(C'\fR afterwards). Otherwise it will create it with the given |
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|
472 | flags, which should almost always be \f(CW0\fR, unless the caller is also the |
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473 | one calling \f(CW\*(C`ev_run\*(C'\fR or otherwise qualifies as \*(L"the main program\*(R". |
437 | .Sp |
474 | .Sp |
438 | If you don't know what event loop to use, use the one returned from this |
475 | If you don't know what event loop to use, use the one returned from this |
439 | function. |
476 | function (or via the \f(CW\*(C`EV_DEFAULT\*(C'\fR macro). |
440 | .Sp |
477 | .Sp |
441 | Note that this function is \fInot\fR thread-safe, so if you want to use it |
478 | Note that this function is \fInot\fR thread-safe, so if you want to use it |
442 | from multiple threads, you have to lock (note also that this is unlikely, |
479 | from multiple threads, you have to employ some kind of mutex (note also |
443 | as loops cannot be shared easily between threads anyway). |
480 | that this case is unlikely, as loops cannot be shared easily between |
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481 | threads anyway). |
444 | .Sp |
482 | .Sp |
445 | The default loop is the only loop that can handle \f(CW\*(C`ev_signal\*(C'\fR and |
483 | The default loop is the only loop that can handle \f(CW\*(C`ev_child\*(C'\fR watchers, |
446 | \&\f(CW\*(C`ev_child\*(C'\fR watchers, and to do this, it always registers a handler |
484 | and to do this, it always registers a handler for \f(CW\*(C`SIGCHLD\*(C'\fR. If this is |
447 | for \f(CW\*(C`SIGCHLD\*(C'\fR. If this is a problem for your application you can either |
485 | a problem for your application you can either create a dynamic loop with |
448 | create a dynamic loop with \f(CW\*(C`ev_loop_new\*(C'\fR that doesn't do that, or you |
486 | \&\f(CW\*(C`ev_loop_new\*(C'\fR which doesn't do that, or you can simply overwrite the |
449 | can simply overwrite the \f(CW\*(C`SIGCHLD\*(C'\fR signal handler \fIafter\fR calling |
487 | \&\f(CW\*(C`SIGCHLD\*(C'\fR signal handler \fIafter\fR calling \f(CW\*(C`ev_default_init\*(C'\fR. |
450 | \&\f(CW\*(C`ev_default_init\*(C'\fR. |
488 | .Sp |
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|
489 | Example: This is the most typical usage. |
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490 | .Sp |
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491 | .Vb 2 |
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|
492 | \& if (!ev_default_loop (0)) |
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|
493 | \& fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?"); |
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494 | .Ve |
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|
495 | .Sp |
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496 | Example: Restrict libev to the select and poll backends, and do not allow |
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497 | environment settings to be taken into account: |
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498 | .Sp |
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499 | .Vb 1 |
|
|
500 | \& ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV); |
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|
501 | .Ve |
|
|
502 | .IP "struct ev_loop *ev_loop_new (unsigned int flags)" 4 |
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|
503 | .IX Item "struct ev_loop *ev_loop_new (unsigned int flags)" |
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|
504 | This will create and initialise a new event loop object. If the loop |
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|
505 | could not be initialised, returns false. |
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|
506 | .Sp |
|
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507 | This function is thread-safe, and one common way to use libev with |
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508 | threads is indeed to create one loop per thread, and using the default |
|
|
509 | loop in the \*(L"main\*(R" or \*(L"initial\*(R" thread. |
451 | .Sp |
510 | .Sp |
452 | The flags argument can be used to specify special behaviour or specific |
511 | The flags argument can be used to specify special behaviour or specific |
453 | backends to use, and is usually specified as \f(CW0\fR (or \f(CW\*(C`EVFLAG_AUTO\*(C'\fR). |
512 | backends to use, and is usually specified as \f(CW0\fR (or \f(CW\*(C`EVFLAG_AUTO\*(C'\fR). |
454 | .Sp |
513 | .Sp |
455 | The following flags are supported: |
514 | The following flags are supported: |
… | |
… | |
464 | .IX Item "EVFLAG_NOENV" |
523 | .IX Item "EVFLAG_NOENV" |
465 | If this flag bit is or'ed into the flag value (or the program runs setuid |
524 | If this flag bit is or'ed into the flag value (or the program runs setuid |
466 | or setgid) then libev will \fInot\fR look at the environment variable |
525 | or setgid) then libev will \fInot\fR look at the environment variable |
467 | \&\f(CW\*(C`LIBEV_FLAGS\*(C'\fR. Otherwise (the default), this environment variable will |
526 | \&\f(CW\*(C`LIBEV_FLAGS\*(C'\fR. Otherwise (the default), this environment variable will |
468 | override the flags completely if it is found in the environment. This is |
527 | override the flags completely if it is found in the environment. This is |
469 | useful to try out specific backends to test their performance, or to work |
528 | useful to try out specific backends to test their performance, to work |
470 | around bugs. |
529 | around bugs, or to make libev threadsafe (accessing environment variables |
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|
530 | cannot be done in a threadsafe way, but usually it works if no other |
|
|
531 | thread modifies them). |
471 | .ie n .IP """EVFLAG_FORKCHECK""" 4 |
532 | .ie n .IP """EVFLAG_FORKCHECK""" 4 |
472 | .el .IP "\f(CWEVFLAG_FORKCHECK\fR" 4 |
533 | .el .IP "\f(CWEVFLAG_FORKCHECK\fR" 4 |
473 | .IX Item "EVFLAG_FORKCHECK" |
534 | .IX Item "EVFLAG_FORKCHECK" |
474 | Instead of calling \f(CW\*(C`ev_default_fork\*(C'\fR or \f(CW\*(C`ev_loop_fork\*(C'\fR manually after |
535 | Instead of calling \f(CW\*(C`ev_loop_fork\*(C'\fR manually after a fork, you can also |
475 | a fork, you can also make libev check for a fork in each iteration by |
536 | make libev check for a fork in each iteration by enabling this flag. |
476 | enabling this flag. |
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|
477 | .Sp |
537 | .Sp |
478 | This works by calling \f(CW\*(C`getpid ()\*(C'\fR on every iteration of the loop, |
538 | This works by calling \f(CW\*(C`getpid ()\*(C'\fR on every iteration of the loop, |
479 | and thus this might slow down your event loop if you do a lot of loop |
539 | and thus this might slow down your event loop if you do a lot of loop |
480 | iterations and little real work, but is usually not noticeable (on my |
540 | iterations and little real work, but is usually not noticeable (on my |
481 | GNU/Linux system for example, \f(CW\*(C`getpid\*(C'\fR is actually a simple 5\-insn sequence |
541 | GNU/Linux system for example, \f(CW\*(C`getpid\*(C'\fR is actually a simple 5\-insn sequence |
… | |
… | |
486 | forget about forgetting to tell libev about forking) when you use this |
546 | forget about forgetting to tell libev about forking) when you use this |
487 | flag. |
547 | flag. |
488 | .Sp |
548 | .Sp |
489 | This flag setting cannot be overridden or specified in the \f(CW\*(C`LIBEV_FLAGS\*(C'\fR |
549 | This flag setting cannot be overridden or specified in the \f(CW\*(C`LIBEV_FLAGS\*(C'\fR |
490 | environment variable. |
550 | environment variable. |
|
|
551 | .ie n .IP """EVFLAG_NOINOTIFY""" 4 |
|
|
552 | .el .IP "\f(CWEVFLAG_NOINOTIFY\fR" 4 |
|
|
553 | .IX Item "EVFLAG_NOINOTIFY" |
|
|
554 | When this flag is specified, then libev will not attempt to use the |
|
|
555 | \&\fIinotify\fR \s-1API\s0 for its \f(CW\*(C`ev_stat\*(C'\fR watchers. Apart from debugging and |
|
|
556 | testing, this flag can be useful to conserve inotify file descriptors, as |
|
|
557 | otherwise each loop using \f(CW\*(C`ev_stat\*(C'\fR watchers consumes one inotify handle. |
|
|
558 | .ie n .IP """EVFLAG_SIGNALFD""" 4 |
|
|
559 | .el .IP "\f(CWEVFLAG_SIGNALFD\fR" 4 |
|
|
560 | .IX Item "EVFLAG_SIGNALFD" |
|
|
561 | When this flag is specified, then libev will attempt to use the |
|
|
562 | \&\fIsignalfd\fR \s-1API\s0 for its \f(CW\*(C`ev_signal\*(C'\fR (and \f(CW\*(C`ev_child\*(C'\fR) watchers. This \s-1API\s0 |
|
|
563 | delivers signals synchronously, which makes it both faster and might make |
|
|
564 | it possible to get the queued signal data. It can also simplify signal |
|
|
565 | handling with threads, as long as you properly block signals in your |
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|
566 | threads that are not interested in handling them. |
|
|
567 | .Sp |
|
|
568 | Signalfd will not be used by default as this changes your signal mask, and |
|
|
569 | there are a lot of shoddy libraries and programs (glib's threadpool for |
|
|
570 | example) that can't properly initialise their signal masks. |
|
|
571 | .ie n .IP """EVFLAG_NOSIGMASK""" 4 |
|
|
572 | .el .IP "\f(CWEVFLAG_NOSIGMASK\fR" 4 |
|
|
573 | .IX Item "EVFLAG_NOSIGMASK" |
|
|
574 | When this flag is specified, then libev will avoid to modify the signal |
|
|
575 | mask. Specifically, this means you have to make sure signals are unblocked |
|
|
576 | when you want to receive them. |
|
|
577 | .Sp |
|
|
578 | This behaviour is useful when you want to do your own signal handling, or |
|
|
579 | want to handle signals only in specific threads and want to avoid libev |
|
|
580 | unblocking the signals. |
|
|
581 | .Sp |
|
|
582 | It's also required by \s-1POSIX\s0 in a threaded program, as libev calls |
|
|
583 | \&\f(CW\*(C`sigprocmask\*(C'\fR, whose behaviour is officially unspecified. |
|
|
584 | .Sp |
|
|
585 | This flag's behaviour will become the default in future versions of libev. |
491 | .ie n .IP """EVBACKEND_SELECT"" (value 1, portable select backend)" 4 |
586 | .ie n .IP """EVBACKEND_SELECT"" (value 1, portable select backend)" 4 |
492 | .el .IP "\f(CWEVBACKEND_SELECT\fR (value 1, portable select backend)" 4 |
587 | .el .IP "\f(CWEVBACKEND_SELECT\fR (value 1, portable select backend)" 4 |
493 | .IX Item "EVBACKEND_SELECT (value 1, portable select backend)" |
588 | .IX Item "EVBACKEND_SELECT (value 1, portable select backend)" |
494 | This is your standard \fIselect\fR\|(2) backend. Not \fIcompletely\fR standard, as |
589 | This is your standard \fIselect\fR\|(2) backend. Not \fIcompletely\fR standard, as |
495 | libev tries to roll its own fd_set with no limits on the number of fds, |
590 | libev tries to roll its own fd_set with no limits on the number of fds, |
496 | but if that fails, expect a fairly low limit on the number of fds when |
591 | but if that fails, expect a fairly low limit on the number of fds when |
497 | using this backend. It doesn't scale too well (O(highest_fd)), but its |
592 | using this backend. It doesn't scale too well (O(highest_fd)), but its |
498 | usually the fastest backend for a low number of (low-numbered :) fds. |
593 | usually the fastest backend for a low number of (low-numbered :) fds. |
… | |
… | |
507 | This backend maps \f(CW\*(C`EV_READ\*(C'\fR to the \f(CW\*(C`readfds\*(C'\fR set and \f(CW\*(C`EV_WRITE\*(C'\fR to the |
602 | This backend maps \f(CW\*(C`EV_READ\*(C'\fR to the \f(CW\*(C`readfds\*(C'\fR set and \f(CW\*(C`EV_WRITE\*(C'\fR to the |
508 | \&\f(CW\*(C`writefds\*(C'\fR set (and to work around Microsoft Windows bugs, also onto the |
603 | \&\f(CW\*(C`writefds\*(C'\fR set (and to work around Microsoft Windows bugs, also onto the |
509 | \&\f(CW\*(C`exceptfds\*(C'\fR set on that platform). |
604 | \&\f(CW\*(C`exceptfds\*(C'\fR set on that platform). |
510 | .ie n .IP """EVBACKEND_POLL"" (value 2, poll backend, available everywhere except on windows)" 4 |
605 | .ie n .IP """EVBACKEND_POLL"" (value 2, poll backend, available everywhere except on windows)" 4 |
511 | .el .IP "\f(CWEVBACKEND_POLL\fR (value 2, poll backend, available everywhere except on windows)" 4 |
606 | .el .IP "\f(CWEVBACKEND_POLL\fR (value 2, poll backend, available everywhere except on windows)" 4 |
512 | .IX Item "EVBACKEND_POLL (value 2, poll backend, available everywhere except on windows)" |
607 | .IX Item "EVBACKEND_POLL (value 2, poll backend, available everywhere except on windows)" |
513 | And this is your standard \fIpoll\fR\|(2) backend. It's more complicated |
608 | And this is your standard \fIpoll\fR\|(2) backend. It's more complicated |
514 | than select, but handles sparse fds better and has no artificial |
609 | than select, but handles sparse fds better and has no artificial |
515 | limit on the number of fds you can use (except it will slow down |
610 | limit on the number of fds you can use (except it will slow down |
516 | considerably with a lot of inactive fds). It scales similarly to select, |
611 | considerably with a lot of inactive fds). It scales similarly to select, |
517 | i.e. O(total_fds). See the entry for \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR, above, for |
612 | i.e. O(total_fds). See the entry for \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR, above, for |
… | |
… | |
519 | .Sp |
614 | .Sp |
520 | This backend maps \f(CW\*(C`EV_READ\*(C'\fR to \f(CW\*(C`POLLIN | POLLERR | POLLHUP\*(C'\fR, and |
615 | This backend maps \f(CW\*(C`EV_READ\*(C'\fR to \f(CW\*(C`POLLIN | POLLERR | POLLHUP\*(C'\fR, and |
521 | \&\f(CW\*(C`EV_WRITE\*(C'\fR to \f(CW\*(C`POLLOUT | POLLERR | POLLHUP\*(C'\fR. |
616 | \&\f(CW\*(C`EV_WRITE\*(C'\fR to \f(CW\*(C`POLLOUT | POLLERR | POLLHUP\*(C'\fR. |
522 | .ie n .IP """EVBACKEND_EPOLL"" (value 4, Linux)" 4 |
617 | .ie n .IP """EVBACKEND_EPOLL"" (value 4, Linux)" 4 |
523 | .el .IP "\f(CWEVBACKEND_EPOLL\fR (value 4, Linux)" 4 |
618 | .el .IP "\f(CWEVBACKEND_EPOLL\fR (value 4, Linux)" 4 |
524 | .IX Item "EVBACKEND_EPOLL (value 4, Linux)" |
619 | .IX Item "EVBACKEND_EPOLL (value 4, Linux)" |
|
|
620 | Use the linux-specific \fIepoll\fR\|(7) interface (for both pre\- and post\-2.6.9 |
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|
621 | kernels). |
|
|
622 | .Sp |
525 | For few fds, this backend is a bit little slower than poll and select, |
623 | For few fds, this backend is a bit little slower than poll and select, but |
526 | but it scales phenomenally better. While poll and select usually scale |
624 | it scales phenomenally better. While poll and select usually scale like |
527 | like O(total_fds) where n is the total number of fds (or the highest fd), |
625 | O(total_fds) where total_fds is the total number of fds (or the highest |
528 | epoll scales either O(1) or O(active_fds). |
626 | fd), epoll scales either O(1) or O(active_fds). |
529 | .Sp |
627 | .Sp |
530 | The epoll mechanism deserves honorable mention as the most misdesigned |
628 | The epoll mechanism deserves honorable mention as the most misdesigned |
531 | of the more advanced event mechanisms: mere annoyances include silently |
629 | of the more advanced event mechanisms: mere annoyances include silently |
532 | dropping file descriptors, requiring a system call per change per file |
630 | dropping file descriptors, requiring a system call per change per file |
533 | descriptor (and unnecessary guessing of parameters), problems with dup and |
631 | descriptor (and unnecessary guessing of parameters), problems with dup, |
|
|
632 | returning before the timeout value, resulting in additional iterations |
|
|
633 | (and only giving 5ms accuracy while select on the same platform gives |
534 | so on. The biggest issue is fork races, however \- if a program forks then |
634 | 0.1ms) and so on. The biggest issue is fork races, however \- if a program |
535 | \&\fIboth\fR parent and child process have to recreate the epoll set, which can |
635 | forks then \fIboth\fR parent and child process have to recreate the epoll |
536 | take considerable time (one syscall per file descriptor) and is of course |
636 | set, which can take considerable time (one syscall per file descriptor) |
537 | hard to detect. |
637 | and is of course hard to detect. |
538 | .Sp |
638 | .Sp |
539 | Epoll is also notoriously buggy \- embedding epoll fds \fIshould\fR work, but |
639 | Epoll is also notoriously buggy \- embedding epoll fds \fIshould\fR work, |
540 | of course \fIdoesn't\fR, and epoll just loves to report events for totally |
640 | but of course \fIdoesn't\fR, and epoll just loves to report events for |
541 | \&\fIdifferent\fR file descriptors (even already closed ones, so one cannot |
641 | totally \fIdifferent\fR file descriptors (even already closed ones, so |
542 | even remove them from the set) than registered in the set (especially |
642 | one cannot even remove them from the set) than registered in the set |
543 | on \s-1SMP\s0 systems). Libev tries to counter these spurious notifications by |
643 | (especially on \s-1SMP\s0 systems). Libev tries to counter these spurious |
544 | employing an additional generation counter and comparing that against the |
644 | notifications by employing an additional generation counter and comparing |
545 | events to filter out spurious ones, recreating the set when required. |
645 | that against the events to filter out spurious ones, recreating the set |
|
|
646 | when required. Epoll also erroneously rounds down timeouts, but gives you |
|
|
647 | no way to know when and by how much, so sometimes you have to busy-wait |
|
|
648 | because epoll returns immediately despite a nonzero timeout. And last |
|
|
649 | not least, it also refuses to work with some file descriptors which work |
|
|
650 | perfectly fine with \f(CW\*(C`select\*(C'\fR (files, many character devices...). |
|
|
651 | .Sp |
|
|
652 | Epoll is truly the train wreck among event poll mechanisms, a frankenpoll, |
|
|
653 | cobbled together in a hurry, no thought to design or interaction with |
|
|
654 | others. Oh, the pain, will it ever stop... |
546 | .Sp |
655 | .Sp |
547 | While stopping, setting and starting an I/O watcher in the same iteration |
656 | While stopping, setting and starting an I/O watcher in the same iteration |
548 | will result in some caching, there is still a system call per such |
657 | will result in some caching, there is still a system call per such |
549 | incident (because the same \fIfile descriptor\fR could point to a different |
658 | incident (because the same \fIfile descriptor\fR could point to a different |
550 | \&\fIfile description\fR now), so its best to avoid that. Also, \f(CW\*(C`dup ()\*(C'\fR'ed |
659 | \&\fIfile description\fR now), so its best to avoid that. Also, \f(CW\*(C`dup ()\*(C'\fR'ed |
… | |
… | |
568 | .Sp |
677 | .Sp |
569 | This backend maps \f(CW\*(C`EV_READ\*(C'\fR and \f(CW\*(C`EV_WRITE\*(C'\fR in the same way as |
678 | This backend maps \f(CW\*(C`EV_READ\*(C'\fR and \f(CW\*(C`EV_WRITE\*(C'\fR in the same way as |
570 | \&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
679 | \&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
571 | .ie n .IP """EVBACKEND_KQUEUE"" (value 8, most \s-1BSD\s0 clones)" 4 |
680 | .ie n .IP """EVBACKEND_KQUEUE"" (value 8, most \s-1BSD\s0 clones)" 4 |
572 | .el .IP "\f(CWEVBACKEND_KQUEUE\fR (value 8, most \s-1BSD\s0 clones)" 4 |
681 | .el .IP "\f(CWEVBACKEND_KQUEUE\fR (value 8, most \s-1BSD\s0 clones)" 4 |
573 | .IX Item "EVBACKEND_KQUEUE (value 8, most BSD clones)" |
682 | .IX Item "EVBACKEND_KQUEUE (value 8, most BSD clones)" |
574 | Kqueue deserves special mention, as at the time of this writing, it |
683 | Kqueue deserves special mention, as at the time of this writing, it |
575 | was broken on all BSDs except NetBSD (usually it doesn't work reliably |
684 | was broken on all BSDs except NetBSD (usually it doesn't work reliably |
576 | with anything but sockets and pipes, except on Darwin, where of course |
685 | with anything but sockets and pipes, except on Darwin, where of course |
577 | it's completely useless). Unlike epoll, however, whose brokenness |
686 | it's completely useless). Unlike epoll, however, whose brokenness |
578 | is by design, these kqueue bugs can (and eventually will) be fixed |
687 | is by design, these kqueue bugs can (and eventually will) be fixed |
… | |
… | |
587 | .Sp |
696 | .Sp |
588 | It scales in the same way as the epoll backend, but the interface to the |
697 | It scales in the same way as the epoll backend, but the interface to the |
589 | kernel is more efficient (which says nothing about its actual speed, of |
698 | kernel is more efficient (which says nothing about its actual speed, of |
590 | course). While stopping, setting and starting an I/O watcher does never |
699 | course). While stopping, setting and starting an I/O watcher does never |
591 | cause an extra system call as with \f(CW\*(C`EVBACKEND_EPOLL\*(C'\fR, it still adds up to |
700 | cause an extra system call as with \f(CW\*(C`EVBACKEND_EPOLL\*(C'\fR, it still adds up to |
592 | two event changes per incident. Support for \f(CW\*(C`fork ()\*(C'\fR is very bad (but |
701 | two event changes per incident. Support for \f(CW\*(C`fork ()\*(C'\fR is very bad (you |
593 | sane, unlike epoll) and it drops fds silently in similarly hard-to-detect |
702 | might have to leak fd's on fork, but it's more sane than epoll) and it |
594 | cases |
703 | drops fds silently in similarly hard-to-detect cases. |
595 | .Sp |
704 | .Sp |
596 | This backend usually performs well under most conditions. |
705 | This backend usually performs well under most conditions. |
597 | .Sp |
706 | .Sp |
598 | While nominally embeddable in other event loops, this doesn't work |
707 | While nominally embeddable in other event loops, this doesn't work |
599 | everywhere, so you might need to test for this. And since it is broken |
708 | everywhere, so you might need to test for this. And since it is broken |
600 | almost everywhere, you should only use it when you have a lot of sockets |
709 | almost everywhere, you should only use it when you have a lot of sockets |
601 | (for which it usually works), by embedding it into another event loop |
710 | (for which it usually works), by embedding it into another event loop |
602 | (e.g. \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or \f(CW\*(C`EVBACKEND_POLL\*(C'\fR (but \f(CW\*(C`poll\*(C'\fR is of course |
711 | (e.g. \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or \f(CW\*(C`EVBACKEND_POLL\*(C'\fR (but \f(CW\*(C`poll\*(C'\fR is of course |
603 | also broken on \s-1OS\s0 X)) and, did I mention it, using it only for sockets. |
712 | also broken on \s-1OS X\s0)) and, did I mention it, using it only for sockets. |
604 | .Sp |
713 | .Sp |
605 | This backend maps \f(CW\*(C`EV_READ\*(C'\fR into an \f(CW\*(C`EVFILT_READ\*(C'\fR kevent with |
714 | This backend maps \f(CW\*(C`EV_READ\*(C'\fR into an \f(CW\*(C`EVFILT_READ\*(C'\fR kevent with |
606 | \&\f(CW\*(C`NOTE_EOF\*(C'\fR, and \f(CW\*(C`EV_WRITE\*(C'\fR into an \f(CW\*(C`EVFILT_WRITE\*(C'\fR kevent with |
715 | \&\f(CW\*(C`NOTE_EOF\*(C'\fR, and \f(CW\*(C`EV_WRITE\*(C'\fR into an \f(CW\*(C`EVFILT_WRITE\*(C'\fR kevent with |
607 | \&\f(CW\*(C`NOTE_EOF\*(C'\fR. |
716 | \&\f(CW\*(C`NOTE_EOF\*(C'\fR. |
608 | .ie n .IP """EVBACKEND_DEVPOLL"" (value 16, Solaris 8)" 4 |
717 | .ie n .IP """EVBACKEND_DEVPOLL"" (value 16, Solaris 8)" 4 |
… | |
… | |
612 | implementation). According to reports, \f(CW\*(C`/dev/poll\*(C'\fR only supports sockets |
721 | implementation). According to reports, \f(CW\*(C`/dev/poll\*(C'\fR only supports sockets |
613 | and is not embeddable, which would limit the usefulness of this backend |
722 | and is not embeddable, which would limit the usefulness of this backend |
614 | immensely. |
723 | immensely. |
615 | .ie n .IP """EVBACKEND_PORT"" (value 32, Solaris 10)" 4 |
724 | .ie n .IP """EVBACKEND_PORT"" (value 32, Solaris 10)" 4 |
616 | .el .IP "\f(CWEVBACKEND_PORT\fR (value 32, Solaris 10)" 4 |
725 | .el .IP "\f(CWEVBACKEND_PORT\fR (value 32, Solaris 10)" 4 |
617 | .IX Item "EVBACKEND_PORT (value 32, Solaris 10)" |
726 | .IX Item "EVBACKEND_PORT (value 32, Solaris 10)" |
618 | This uses the Solaris 10 event port mechanism. As with everything on Solaris, |
727 | This uses the Solaris 10 event port mechanism. As with everything on Solaris, |
619 | it's really slow, but it still scales very well (O(active_fds)). |
728 | it's really slow, but it still scales very well (O(active_fds)). |
620 | .Sp |
|
|
621 | Please note that Solaris event ports can deliver a lot of spurious |
|
|
622 | notifications, so you need to use non-blocking I/O or other means to avoid |
|
|
623 | blocking when no data (or space) is available. |
|
|
624 | .Sp |
729 | .Sp |
625 | While this backend scales well, it requires one system call per active |
730 | While this backend scales well, it requires one system call per active |
626 | file descriptor per loop iteration. For small and medium numbers of file |
731 | file descriptor per loop iteration. For small and medium numbers of file |
627 | descriptors a \*(L"slow\*(R" \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or \f(CW\*(C`EVBACKEND_POLL\*(C'\fR backend |
732 | descriptors a \*(L"slow\*(R" \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or \f(CW\*(C`EVBACKEND_POLL\*(C'\fR backend |
628 | might perform better. |
733 | might perform better. |
629 | .Sp |
734 | .Sp |
630 | On the positive side, with the exception of the spurious readiness |
735 | On the positive side, this backend actually performed fully to |
631 | notifications, this backend actually performed fully to specification |
|
|
632 | in all tests and is fully embeddable, which is a rare feat among the |
736 | specification in all tests and is fully embeddable, which is a rare feat |
633 | OS-specific backends (I vastly prefer correctness over speed hacks). |
737 | among the OS-specific backends (I vastly prefer correctness over speed |
|
|
738 | hacks). |
|
|
739 | .Sp |
|
|
740 | On the negative side, the interface is \fIbizarre\fR \- so bizarre that |
|
|
741 | even sun itself gets it wrong in their code examples: The event polling |
|
|
742 | function sometimes returns events to the caller even though an error |
|
|
743 | occurred, but with no indication whether it has done so or not (yes, it's |
|
|
744 | even documented that way) \- deadly for edge-triggered interfaces where you |
|
|
745 | absolutely have to know whether an event occurred or not because you have |
|
|
746 | to re-arm the watcher. |
|
|
747 | .Sp |
|
|
748 | Fortunately libev seems to be able to work around these idiocies. |
634 | .Sp |
749 | .Sp |
635 | This backend maps \f(CW\*(C`EV_READ\*(C'\fR and \f(CW\*(C`EV_WRITE\*(C'\fR in the same way as |
750 | This backend maps \f(CW\*(C`EV_READ\*(C'\fR and \f(CW\*(C`EV_WRITE\*(C'\fR in the same way as |
636 | \&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
751 | \&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
637 | .ie n .IP """EVBACKEND_ALL""" 4 |
752 | .ie n .IP """EVBACKEND_ALL""" 4 |
638 | .el .IP "\f(CWEVBACKEND_ALL\fR" 4 |
753 | .el .IP "\f(CWEVBACKEND_ALL\fR" 4 |
639 | .IX Item "EVBACKEND_ALL" |
754 | .IX Item "EVBACKEND_ALL" |
640 | Try all backends (even potentially broken ones that wouldn't be tried |
755 | Try all backends (even potentially broken ones that wouldn't be tried |
641 | with \f(CW\*(C`EVFLAG_AUTO\*(C'\fR). Since this is a mask, you can do stuff such as |
756 | with \f(CW\*(C`EVFLAG_AUTO\*(C'\fR). Since this is a mask, you can do stuff such as |
642 | \&\f(CW\*(C`EVBACKEND_ALL & ~EVBACKEND_KQUEUE\*(C'\fR. |
757 | \&\f(CW\*(C`EVBACKEND_ALL & ~EVBACKEND_KQUEUE\*(C'\fR. |
643 | .Sp |
758 | .Sp |
644 | It is definitely not recommended to use this flag. |
759 | It is definitely not recommended to use this flag, use whatever |
|
|
760 | \&\f(CW\*(C`ev_recommended_backends ()\*(C'\fR returns, or simply do not specify a backend |
|
|
761 | at all. |
|
|
762 | .ie n .IP """EVBACKEND_MASK""" 4 |
|
|
763 | .el .IP "\f(CWEVBACKEND_MASK\fR" 4 |
|
|
764 | .IX Item "EVBACKEND_MASK" |
|
|
765 | Not a backend at all, but a mask to select all backend bits from a |
|
|
766 | \&\f(CW\*(C`flags\*(C'\fR value, in case you want to mask out any backends from a flags |
|
|
767 | value (e.g. when modifying the \f(CW\*(C`LIBEV_FLAGS\*(C'\fR environment variable). |
645 | .RE |
768 | .RE |
646 | .RS 4 |
769 | .RS 4 |
647 | .Sp |
770 | .Sp |
648 | If one or more of these are or'ed into the flags value, then only these |
771 | If one or more of the backend flags are or'ed into the flags value, |
649 | backends will be tried (in the reverse order as listed here). If none are |
772 | then only these backends will be tried (in the reverse order as listed |
650 | specified, all backends in \f(CW\*(C`ev_recommended_backends ()\*(C'\fR will be tried. |
773 | here). If none are specified, all backends in \f(CW\*(C`ev_recommended_backends |
651 | .Sp |
774 | ()\*(C'\fR will be tried. |
652 | Example: This is the most typical usage. |
|
|
653 | .Sp |
|
|
654 | .Vb 2 |
|
|
655 | \& if (!ev_default_loop (0)) |
|
|
656 | \& fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?"); |
|
|
657 | .Ve |
|
|
658 | .Sp |
|
|
659 | Example: Restrict libev to the select and poll backends, and do not allow |
|
|
660 | environment settings to be taken into account: |
|
|
661 | .Sp |
|
|
662 | .Vb 1 |
|
|
663 | \& ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV); |
|
|
664 | .Ve |
|
|
665 | .Sp |
|
|
666 | Example: Use whatever libev has to offer, but make sure that kqueue is |
|
|
667 | used if available (warning, breaks stuff, best use only with your own |
|
|
668 | private event loop and only if you know the \s-1OS\s0 supports your types of |
|
|
669 | fds): |
|
|
670 | .Sp |
|
|
671 | .Vb 1 |
|
|
672 | \& ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE); |
|
|
673 | .Ve |
|
|
674 | .RE |
|
|
675 | .IP "struct ev_loop *ev_loop_new (unsigned int flags)" 4 |
|
|
676 | .IX Item "struct ev_loop *ev_loop_new (unsigned int flags)" |
|
|
677 | Similar to \f(CW\*(C`ev_default_loop\*(C'\fR, but always creates a new event loop that is |
|
|
678 | always distinct from the default loop. Unlike the default loop, it cannot |
|
|
679 | handle signal and child watchers, and attempts to do so will be greeted by |
|
|
680 | undefined behaviour (or a failed assertion if assertions are enabled). |
|
|
681 | .Sp |
|
|
682 | Note that this function \fIis\fR thread-safe, and the recommended way to use |
|
|
683 | libev with threads is indeed to create one loop per thread, and using the |
|
|
684 | default loop in the \*(L"main\*(R" or \*(L"initial\*(R" thread. |
|
|
685 | .Sp |
775 | .Sp |
686 | Example: Try to create a event loop that uses epoll and nothing else. |
776 | Example: Try to create a event loop that uses epoll and nothing else. |
687 | .Sp |
777 | .Sp |
688 | .Vb 3 |
778 | .Vb 3 |
689 | \& struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); |
779 | \& struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); |
690 | \& if (!epoller) |
780 | \& if (!epoller) |
691 | \& fatal ("no epoll found here, maybe it hides under your chair"); |
781 | \& fatal ("no epoll found here, maybe it hides under your chair"); |
692 | .Ve |
782 | .Ve |
|
|
783 | .Sp |
|
|
784 | Example: Use whatever libev has to offer, but make sure that kqueue is |
|
|
785 | used if available. |
|
|
786 | .Sp |
|
|
787 | .Vb 1 |
|
|
788 | \& struct ev_loop *loop = ev_loop_new (ev_recommended_backends () | EVBACKEND_KQUEUE); |
|
|
789 | .Ve |
|
|
790 | .RE |
693 | .IP "ev_default_destroy ()" 4 |
791 | .IP "ev_loop_destroy (loop)" 4 |
694 | .IX Item "ev_default_destroy ()" |
792 | .IX Item "ev_loop_destroy (loop)" |
695 | Destroys the default loop again (frees all memory and kernel state |
793 | Destroys an event loop object (frees all memory and kernel state |
696 | etc.). None of the active event watchers will be stopped in the normal |
794 | etc.). None of the active event watchers will be stopped in the normal |
697 | sense, so e.g. \f(CW\*(C`ev_is_active\*(C'\fR might still return true. It is your |
795 | sense, so e.g. \f(CW\*(C`ev_is_active\*(C'\fR might still return true. It is your |
698 | responsibility to either stop all watchers cleanly yourself \fIbefore\fR |
796 | responsibility to either stop all watchers cleanly yourself \fIbefore\fR |
699 | calling this function, or cope with the fact afterwards (which is usually |
797 | calling this function, or cope with the fact afterwards (which is usually |
700 | the easiest thing, you can just ignore the watchers and/or \f(CW\*(C`free ()\*(C'\fR them |
798 | the easiest thing, you can just ignore the watchers and/or \f(CW\*(C`free ()\*(C'\fR them |
… | |
… | |
702 | .Sp |
800 | .Sp |
703 | Note that certain global state, such as signal state (and installed signal |
801 | Note that certain global state, such as signal state (and installed signal |
704 | handlers), will not be freed by this function, and related watchers (such |
802 | handlers), will not be freed by this function, and related watchers (such |
705 | as signal and child watchers) would need to be stopped manually. |
803 | as signal and child watchers) would need to be stopped manually. |
706 | .Sp |
804 | .Sp |
707 | In general it is not advisable to call this function except in the |
805 | This function is normally used on loop objects allocated by |
708 | rare occasion where you really need to free e.g. the signal handling |
806 | \&\f(CW\*(C`ev_loop_new\*(C'\fR, but it can also be used on the default loop returned by |
709 | pipe fds. If you need dynamically allocated loops it is better to use |
807 | \&\f(CW\*(C`ev_default_loop\*(C'\fR, in which case it is not thread-safe. |
710 | \&\f(CW\*(C`ev_loop_new\*(C'\fR and \f(CW\*(C`ev_loop_destroy\*(C'\fR). |
|
|
711 | .IP "ev_loop_destroy (loop)" 4 |
|
|
712 | .IX Item "ev_loop_destroy (loop)" |
|
|
713 | Like \f(CW\*(C`ev_default_destroy\*(C'\fR, but destroys an event loop created by an |
|
|
714 | earlier call to \f(CW\*(C`ev_loop_new\*(C'\fR. |
|
|
715 | .IP "ev_default_fork ()" 4 |
|
|
716 | .IX Item "ev_default_fork ()" |
|
|
717 | This function sets a flag that causes subsequent \f(CW\*(C`ev_loop\*(C'\fR iterations |
|
|
718 | to reinitialise the kernel state for backends that have one. Despite the |
|
|
719 | name, you can call it anytime, but it makes most sense after forking, in |
|
|
720 | the child process (or both child and parent, but that again makes little |
|
|
721 | sense). You \fImust\fR call it in the child before using any of the libev |
|
|
722 | functions, and it will only take effect at the next \f(CW\*(C`ev_loop\*(C'\fR iteration. |
|
|
723 | .Sp |
808 | .Sp |
724 | On the other hand, you only need to call this function in the child |
809 | Note that it is not advisable to call this function on the default loop |
725 | process if and only if you want to use the event library in the child. If |
810 | except in the rare occasion where you really need to free its resources. |
726 | you just fork+exec, you don't have to call it at all. |
811 | If you need dynamically allocated loops it is better to use \f(CW\*(C`ev_loop_new\*(C'\fR |
727 | .Sp |
812 | and \f(CW\*(C`ev_loop_destroy\*(C'\fR. |
728 | The function itself is quite fast and it's usually not a problem to call |
|
|
729 | it just in case after a fork. To make this easy, the function will fit in |
|
|
730 | quite nicely into a call to \f(CW\*(C`pthread_atfork\*(C'\fR: |
|
|
731 | .Sp |
|
|
732 | .Vb 1 |
|
|
733 | \& pthread_atfork (0, 0, ev_default_fork); |
|
|
734 | .Ve |
|
|
735 | .IP "ev_loop_fork (loop)" 4 |
813 | .IP "ev_loop_fork (loop)" 4 |
736 | .IX Item "ev_loop_fork (loop)" |
814 | .IX Item "ev_loop_fork (loop)" |
737 | Like \f(CW\*(C`ev_default_fork\*(C'\fR, but acts on an event loop created by |
815 | This function sets a flag that causes subsequent \f(CW\*(C`ev_run\*(C'\fR iterations |
738 | \&\f(CW\*(C`ev_loop_new\*(C'\fR. Yes, you have to call this on every allocated event loop |
816 | to reinitialise the kernel state for backends that have one. Despite |
739 | after fork that you want to re-use in the child, and how you do this is |
817 | the name, you can call it anytime you are allowed to start or stop |
740 | entirely your own problem. |
818 | watchers (except inside an \f(CW\*(C`ev_prepare\*(C'\fR callback), but it makes most |
|
|
819 | sense after forking, in the child process. You \fImust\fR call it (or use |
|
|
820 | \&\f(CW\*(C`EVFLAG_FORKCHECK\*(C'\fR) in the child before resuming or calling \f(CW\*(C`ev_run\*(C'\fR. |
|
|
821 | .Sp |
|
|
822 | Again, you \fIhave\fR to call it on \fIany\fR loop that you want to re-use after |
|
|
823 | a fork, \fIeven if you do not plan to use the loop in the parent\fR. This is |
|
|
824 | because some kernel interfaces *cough* \fIkqueue\fR *cough* do funny things |
|
|
825 | during fork. |
|
|
826 | .Sp |
|
|
827 | On the other hand, you only need to call this function in the child |
|
|
828 | process if and only if you want to use the event loop in the child. If |
|
|
829 | you just fork+exec or create a new loop in the child, you don't have to |
|
|
830 | call it at all (in fact, \f(CW\*(C`epoll\*(C'\fR is so badly broken that it makes a |
|
|
831 | difference, but libev will usually detect this case on its own and do a |
|
|
832 | costly reset of the backend). |
|
|
833 | .Sp |
|
|
834 | The function itself is quite fast and it's usually not a problem to call |
|
|
835 | it just in case after a fork. |
|
|
836 | .Sp |
|
|
837 | Example: Automate calling \f(CW\*(C`ev_loop_fork\*(C'\fR on the default loop when |
|
|
838 | using pthreads. |
|
|
839 | .Sp |
|
|
840 | .Vb 5 |
|
|
841 | \& static void |
|
|
842 | \& post_fork_child (void) |
|
|
843 | \& { |
|
|
844 | \& ev_loop_fork (EV_DEFAULT); |
|
|
845 | \& } |
|
|
846 | \& |
|
|
847 | \& ... |
|
|
848 | \& pthread_atfork (0, 0, post_fork_child); |
|
|
849 | .Ve |
741 | .IP "int ev_is_default_loop (loop)" 4 |
850 | .IP "int ev_is_default_loop (loop)" 4 |
742 | .IX Item "int ev_is_default_loop (loop)" |
851 | .IX Item "int ev_is_default_loop (loop)" |
743 | Returns true when the given loop is, in fact, the default loop, and false |
852 | Returns true when the given loop is, in fact, the default loop, and false |
744 | otherwise. |
853 | otherwise. |
745 | .IP "unsigned int ev_loop_count (loop)" 4 |
854 | .IP "unsigned int ev_iteration (loop)" 4 |
746 | .IX Item "unsigned int ev_loop_count (loop)" |
855 | .IX Item "unsigned int ev_iteration (loop)" |
747 | Returns the count of loop iterations for the loop, which is identical to |
856 | Returns the current iteration count for the event loop, which is identical |
748 | the number of times libev did poll for new events. It starts at \f(CW0\fR and |
857 | to the number of times libev did poll for new events. It starts at \f(CW0\fR |
749 | happily wraps around with enough iterations. |
858 | and happily wraps around with enough iterations. |
750 | .Sp |
859 | .Sp |
751 | This value can sometimes be useful as a generation counter of sorts (it |
860 | This value can sometimes be useful as a generation counter of sorts (it |
752 | \&\*(L"ticks\*(R" the number of loop iterations), as it roughly corresponds with |
861 | \&\*(L"ticks\*(R" the number of loop iterations), as it roughly corresponds with |
753 | \&\f(CW\*(C`ev_prepare\*(C'\fR and \f(CW\*(C`ev_check\*(C'\fR calls. |
862 | \&\f(CW\*(C`ev_prepare\*(C'\fR and \f(CW\*(C`ev_check\*(C'\fR calls \- and is incremented between the |
|
|
863 | prepare and check phases. |
|
|
864 | .IP "unsigned int ev_depth (loop)" 4 |
|
|
865 | .IX Item "unsigned int ev_depth (loop)" |
|
|
866 | Returns the number of times \f(CW\*(C`ev_run\*(C'\fR was entered minus the number of |
|
|
867 | times \f(CW\*(C`ev_run\*(C'\fR was exited normally, in other words, the recursion depth. |
|
|
868 | .Sp |
|
|
869 | Outside \f(CW\*(C`ev_run\*(C'\fR, this number is zero. In a callback, this number is |
|
|
870 | \&\f(CW1\fR, unless \f(CW\*(C`ev_run\*(C'\fR was invoked recursively (or from another thread), |
|
|
871 | in which case it is higher. |
|
|
872 | .Sp |
|
|
873 | Leaving \f(CW\*(C`ev_run\*(C'\fR abnormally (setjmp/longjmp, cancelling the thread, |
|
|
874 | throwing an exception etc.), doesn't count as \*(L"exit\*(R" \- consider this |
|
|
875 | as a hint to avoid such ungentleman-like behaviour unless it's really |
|
|
876 | convenient, in which case it is fully supported. |
754 | .IP "unsigned int ev_backend (loop)" 4 |
877 | .IP "unsigned int ev_backend (loop)" 4 |
755 | .IX Item "unsigned int ev_backend (loop)" |
878 | .IX Item "unsigned int ev_backend (loop)" |
756 | Returns one of the \f(CW\*(C`EVBACKEND_*\*(C'\fR flags indicating the event backend in |
879 | Returns one of the \f(CW\*(C`EVBACKEND_*\*(C'\fR flags indicating the event backend in |
757 | use. |
880 | use. |
758 | .IP "ev_tstamp ev_now (loop)" 4 |
881 | .IP "ev_tstamp ev_now (loop)" 4 |
… | |
… | |
764 | event occurring (or more correctly, libev finding out about it). |
887 | event occurring (or more correctly, libev finding out about it). |
765 | .IP "ev_now_update (loop)" 4 |
888 | .IP "ev_now_update (loop)" 4 |
766 | .IX Item "ev_now_update (loop)" |
889 | .IX Item "ev_now_update (loop)" |
767 | Establishes the current time by querying the kernel, updating the time |
890 | Establishes the current time by querying the kernel, updating the time |
768 | returned by \f(CW\*(C`ev_now ()\*(C'\fR in the progress. This is a costly operation and |
891 | returned by \f(CW\*(C`ev_now ()\*(C'\fR in the progress. This is a costly operation and |
769 | is usually done automatically within \f(CW\*(C`ev_loop ()\*(C'\fR. |
892 | is usually done automatically within \f(CW\*(C`ev_run ()\*(C'\fR. |
770 | .Sp |
893 | .Sp |
771 | This function is rarely useful, but when some event callback runs for a |
894 | This function is rarely useful, but when some event callback runs for a |
772 | very long time without entering the event loop, updating libev's idea of |
895 | very long time without entering the event loop, updating libev's idea of |
773 | the current time is a good idea. |
896 | the current time is a good idea. |
774 | .Sp |
897 | .Sp |
… | |
… | |
777 | .IX Item "ev_suspend (loop)" |
900 | .IX Item "ev_suspend (loop)" |
778 | .PD 0 |
901 | .PD 0 |
779 | .IP "ev_resume (loop)" 4 |
902 | .IP "ev_resume (loop)" 4 |
780 | .IX Item "ev_resume (loop)" |
903 | .IX Item "ev_resume (loop)" |
781 | .PD |
904 | .PD |
782 | These two functions suspend and resume a loop, for use when the loop is |
905 | These two functions suspend and resume an event loop, for use when the |
783 | not used for a while and timeouts should not be processed. |
906 | loop is not used for a while and timeouts should not be processed. |
784 | .Sp |
907 | .Sp |
785 | A typical use case would be an interactive program such as a game: When |
908 | A typical use case would be an interactive program such as a game: When |
786 | the user presses \f(CW\*(C`^Z\*(C'\fR to suspend the game and resumes it an hour later it |
909 | the user presses \f(CW\*(C`^Z\*(C'\fR to suspend the game and resumes it an hour later it |
787 | would be best to handle timeouts as if no time had actually passed while |
910 | would be best to handle timeouts as if no time had actually passed while |
788 | the program was suspended. This can be achieved by calling \f(CW\*(C`ev_suspend\*(C'\fR |
911 | the program was suspended. This can be achieved by calling \f(CW\*(C`ev_suspend\*(C'\fR |
… | |
… | |
790 | \&\f(CW\*(C`ev_resume\*(C'\fR directly afterwards to resume timer processing. |
913 | \&\f(CW\*(C`ev_resume\*(C'\fR directly afterwards to resume timer processing. |
791 | .Sp |
914 | .Sp |
792 | Effectively, all \f(CW\*(C`ev_timer\*(C'\fR watchers will be delayed by the time spend |
915 | Effectively, all \f(CW\*(C`ev_timer\*(C'\fR watchers will be delayed by the time spend |
793 | between \f(CW\*(C`ev_suspend\*(C'\fR and \f(CW\*(C`ev_resume\*(C'\fR, and all \f(CW\*(C`ev_periodic\*(C'\fR watchers |
916 | between \f(CW\*(C`ev_suspend\*(C'\fR and \f(CW\*(C`ev_resume\*(C'\fR, and all \f(CW\*(C`ev_periodic\*(C'\fR watchers |
794 | will be rescheduled (that is, they will lose any events that would have |
917 | will be rescheduled (that is, they will lose any events that would have |
795 | occured while suspended). |
918 | occurred while suspended). |
796 | .Sp |
919 | .Sp |
797 | After calling \f(CW\*(C`ev_suspend\*(C'\fR you \fBmust not\fR call \fIany\fR function on the |
920 | After calling \f(CW\*(C`ev_suspend\*(C'\fR you \fBmust not\fR call \fIany\fR function on the |
798 | given loop other than \f(CW\*(C`ev_resume\*(C'\fR, and you \fBmust not\fR call \f(CW\*(C`ev_resume\*(C'\fR |
921 | given loop other than \f(CW\*(C`ev_resume\*(C'\fR, and you \fBmust not\fR call \f(CW\*(C`ev_resume\*(C'\fR |
799 | without a previous call to \f(CW\*(C`ev_suspend\*(C'\fR. |
922 | without a previous call to \f(CW\*(C`ev_suspend\*(C'\fR. |
800 | .Sp |
923 | .Sp |
801 | Calling \f(CW\*(C`ev_suspend\*(C'\fR/\f(CW\*(C`ev_resume\*(C'\fR has the side effect of updating the |
924 | Calling \f(CW\*(C`ev_suspend\*(C'\fR/\f(CW\*(C`ev_resume\*(C'\fR has the side effect of updating the |
802 | event loop time (see \f(CW\*(C`ev_now_update\*(C'\fR). |
925 | event loop time (see \f(CW\*(C`ev_now_update\*(C'\fR). |
803 | .IP "ev_loop (loop, int flags)" 4 |
926 | .IP "bool ev_run (loop, int flags)" 4 |
804 | .IX Item "ev_loop (loop, int flags)" |
927 | .IX Item "bool ev_run (loop, int flags)" |
805 | Finally, this is it, the event handler. This function usually is called |
928 | Finally, this is it, the event handler. This function usually is called |
806 | after you initialised all your watchers and you want to start handling |
929 | after you have initialised all your watchers and you want to start |
807 | events. |
930 | handling events. It will ask the operating system for any new events, call |
|
|
931 | the watcher callbacks, and then repeat the whole process indefinitely: This |
|
|
932 | is why event loops are called \fIloops\fR. |
808 | .Sp |
933 | .Sp |
809 | If the flags argument is specified as \f(CW0\fR, it will not return until |
934 | If the flags argument is specified as \f(CW0\fR, it will keep handling events |
810 | either no event watchers are active anymore or \f(CW\*(C`ev_unloop\*(C'\fR was called. |
935 | until either no event watchers are active anymore or \f(CW\*(C`ev_break\*(C'\fR was |
|
|
936 | called. |
811 | .Sp |
937 | .Sp |
|
|
938 | The return value is false if there are no more active watchers (which |
|
|
939 | usually means \*(L"all jobs done\*(R" or \*(L"deadlock\*(R"), and true in all other cases |
|
|
940 | (which usually means " you should call \f(CW\*(C`ev_run\*(C'\fR again"). |
|
|
941 | .Sp |
812 | Please note that an explicit \f(CW\*(C`ev_unloop\*(C'\fR is usually better than |
942 | Please note that an explicit \f(CW\*(C`ev_break\*(C'\fR is usually better than |
813 | relying on all watchers to be stopped when deciding when a program has |
943 | relying on all watchers to be stopped when deciding when a program has |
814 | finished (especially in interactive programs), but having a program |
944 | finished (especially in interactive programs), but having a program |
815 | that automatically loops as long as it has to and no longer by virtue |
945 | that automatically loops as long as it has to and no longer by virtue |
816 | of relying on its watchers stopping correctly, that is truly a thing of |
946 | of relying on its watchers stopping correctly, that is truly a thing of |
817 | beauty. |
947 | beauty. |
818 | .Sp |
948 | .Sp |
|
|
949 | This function is \fImostly\fR exception-safe \- you can break out of a |
|
|
950 | \&\f(CW\*(C`ev_run\*(C'\fR call by calling \f(CW\*(C`longjmp\*(C'\fR in a callback, throwing a \*(C+ |
|
|
951 | exception and so on. This does not decrement the \f(CW\*(C`ev_depth\*(C'\fR value, nor |
|
|
952 | will it clear any outstanding \f(CW\*(C`EVBREAK_ONE\*(C'\fR breaks. |
|
|
953 | .Sp |
819 | A flags value of \f(CW\*(C`EVLOOP_NONBLOCK\*(C'\fR will look for new events, will handle |
954 | A flags value of \f(CW\*(C`EVRUN_NOWAIT\*(C'\fR will look for new events, will handle |
820 | those events and any already outstanding ones, but will not block your |
955 | those events and any already outstanding ones, but will not wait and |
821 | process in case there are no events and will return after one iteration of |
956 | block your process in case there are no events and will return after one |
822 | the loop. |
957 | iteration of the loop. This is sometimes useful to poll and handle new |
|
|
958 | events while doing lengthy calculations, to keep the program responsive. |
823 | .Sp |
959 | .Sp |
824 | A flags value of \f(CW\*(C`EVLOOP_ONESHOT\*(C'\fR will look for new events (waiting if |
960 | A flags value of \f(CW\*(C`EVRUN_ONCE\*(C'\fR will look for new events (waiting if |
825 | necessary) and will handle those and any already outstanding ones. It |
961 | necessary) and will handle those and any already outstanding ones. It |
826 | will block your process until at least one new event arrives (which could |
962 | will block your process until at least one new event arrives (which could |
827 | be an event internal to libev itself, so there is no guarantee that a |
963 | be an event internal to libev itself, so there is no guarantee that a |
828 | user-registered callback will be called), and will return after one |
964 | user-registered callback will be called), and will return after one |
829 | iteration of the loop. |
965 | iteration of the loop. |
830 | .Sp |
966 | .Sp |
831 | This is useful if you are waiting for some external event in conjunction |
967 | This is useful if you are waiting for some external event in conjunction |
832 | with something not expressible using other libev watchers (i.e. "roll your |
968 | with something not expressible using other libev watchers (i.e. "roll your |
833 | own \f(CW\*(C`ev_loop\*(C'\fR"). However, a pair of \f(CW\*(C`ev_prepare\*(C'\fR/\f(CW\*(C`ev_check\*(C'\fR watchers is |
969 | own \f(CW\*(C`ev_run\*(C'\fR"). However, a pair of \f(CW\*(C`ev_prepare\*(C'\fR/\f(CW\*(C`ev_check\*(C'\fR watchers is |
834 | usually a better approach for this kind of thing. |
970 | usually a better approach for this kind of thing. |
835 | .Sp |
971 | .Sp |
836 | Here are the gory details of what \f(CW\*(C`ev_loop\*(C'\fR does: |
972 | Here are the gory details of what \f(CW\*(C`ev_run\*(C'\fR does (this is for your |
|
|
973 | understanding, not a guarantee that things will work exactly like this in |
|
|
974 | future versions): |
837 | .Sp |
975 | .Sp |
838 | .Vb 10 |
976 | .Vb 10 |
|
|
977 | \& \- Increment loop depth. |
|
|
978 | \& \- Reset the ev_break status. |
839 | \& \- Before the first iteration, call any pending watchers. |
979 | \& \- Before the first iteration, call any pending watchers. |
|
|
980 | \& LOOP: |
840 | \& * If EVFLAG_FORKCHECK was used, check for a fork. |
981 | \& \- If EVFLAG_FORKCHECK was used, check for a fork. |
841 | \& \- If a fork was detected (by any means), queue and call all fork watchers. |
982 | \& \- If a fork was detected (by any means), queue and call all fork watchers. |
842 | \& \- Queue and call all prepare watchers. |
983 | \& \- Queue and call all prepare watchers. |
|
|
984 | \& \- If ev_break was called, goto FINISH. |
843 | \& \- If we have been forked, detach and recreate the kernel state |
985 | \& \- If we have been forked, detach and recreate the kernel state |
844 | \& as to not disturb the other process. |
986 | \& as to not disturb the other process. |
845 | \& \- Update the kernel state with all outstanding changes. |
987 | \& \- Update the kernel state with all outstanding changes. |
846 | \& \- Update the "event loop time" (ev_now ()). |
988 | \& \- Update the "event loop time" (ev_now ()). |
847 | \& \- Calculate for how long to sleep or block, if at all |
989 | \& \- Calculate for how long to sleep or block, if at all |
848 | \& (active idle watchers, EVLOOP_NONBLOCK or not having |
990 | \& (active idle watchers, EVRUN_NOWAIT or not having |
849 | \& any active watchers at all will result in not sleeping). |
991 | \& any active watchers at all will result in not sleeping). |
850 | \& \- Sleep if the I/O and timer collect interval say so. |
992 | \& \- Sleep if the I/O and timer collect interval say so. |
|
|
993 | \& \- Increment loop iteration counter. |
851 | \& \- Block the process, waiting for any events. |
994 | \& \- Block the process, waiting for any events. |
852 | \& \- Queue all outstanding I/O (fd) events. |
995 | \& \- Queue all outstanding I/O (fd) events. |
853 | \& \- Update the "event loop time" (ev_now ()), and do time jump adjustments. |
996 | \& \- Update the "event loop time" (ev_now ()), and do time jump adjustments. |
854 | \& \- Queue all expired timers. |
997 | \& \- Queue all expired timers. |
855 | \& \- Queue all expired periodics. |
998 | \& \- Queue all expired periodics. |
856 | \& \- Unless any events are pending now, queue all idle watchers. |
999 | \& \- Queue all idle watchers with priority higher than that of pending events. |
857 | \& \- Queue all check watchers. |
1000 | \& \- Queue all check watchers. |
858 | \& \- Call all queued watchers in reverse order (i.e. check watchers first). |
1001 | \& \- Call all queued watchers in reverse order (i.e. check watchers first). |
859 | \& Signals and child watchers are implemented as I/O watchers, and will |
1002 | \& Signals and child watchers are implemented as I/O watchers, and will |
860 | \& be handled here by queueing them when their watcher gets executed. |
1003 | \& be handled here by queueing them when their watcher gets executed. |
861 | \& \- If ev_unloop has been called, or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
1004 | \& \- If ev_break has been called, or EVRUN_ONCE or EVRUN_NOWAIT |
862 | \& were used, or there are no active watchers, return, otherwise |
1005 | \& were used, or there are no active watchers, goto FINISH, otherwise |
863 | \& continue with step *. |
1006 | \& continue with step LOOP. |
|
|
1007 | \& FINISH: |
|
|
1008 | \& \- Reset the ev_break status iff it was EVBREAK_ONE. |
|
|
1009 | \& \- Decrement the loop depth. |
|
|
1010 | \& \- Return. |
864 | .Ve |
1011 | .Ve |
865 | .Sp |
1012 | .Sp |
866 | Example: Queue some jobs and then loop until no events are outstanding |
1013 | Example: Queue some jobs and then loop until no events are outstanding |
867 | anymore. |
1014 | anymore. |
868 | .Sp |
1015 | .Sp |
869 | .Vb 4 |
1016 | .Vb 4 |
870 | \& ... queue jobs here, make sure they register event watchers as long |
1017 | \& ... queue jobs here, make sure they register event watchers as long |
871 | \& ... as they still have work to do (even an idle watcher will do..) |
1018 | \& ... as they still have work to do (even an idle watcher will do..) |
872 | \& ev_loop (my_loop, 0); |
1019 | \& ev_run (my_loop, 0); |
873 | \& ... jobs done or somebody called unloop. yeah! |
1020 | \& ... jobs done or somebody called break. yeah! |
874 | .Ve |
1021 | .Ve |
875 | .IP "ev_unloop (loop, how)" 4 |
1022 | .IP "ev_break (loop, how)" 4 |
876 | .IX Item "ev_unloop (loop, how)" |
1023 | .IX Item "ev_break (loop, how)" |
877 | Can be used to make a call to \f(CW\*(C`ev_loop\*(C'\fR return early (but only after it |
1024 | Can be used to make a call to \f(CW\*(C`ev_run\*(C'\fR return early (but only after it |
878 | has processed all outstanding events). The \f(CW\*(C`how\*(C'\fR argument must be either |
1025 | has processed all outstanding events). The \f(CW\*(C`how\*(C'\fR argument must be either |
879 | \&\f(CW\*(C`EVUNLOOP_ONE\*(C'\fR, which will make the innermost \f(CW\*(C`ev_loop\*(C'\fR call return, or |
1026 | \&\f(CW\*(C`EVBREAK_ONE\*(C'\fR, which will make the innermost \f(CW\*(C`ev_run\*(C'\fR call return, or |
880 | \&\f(CW\*(C`EVUNLOOP_ALL\*(C'\fR, which will make all nested \f(CW\*(C`ev_loop\*(C'\fR calls return. |
1027 | \&\f(CW\*(C`EVBREAK_ALL\*(C'\fR, which will make all nested \f(CW\*(C`ev_run\*(C'\fR calls return. |
881 | .Sp |
1028 | .Sp |
882 | This \*(L"unloop state\*(R" will be cleared when entering \f(CW\*(C`ev_loop\*(C'\fR again. |
1029 | This \*(L"break state\*(R" will be cleared on the next call to \f(CW\*(C`ev_run\*(C'\fR. |
883 | .Sp |
1030 | .Sp |
884 | It is safe to call \f(CW\*(C`ev_unloop\*(C'\fR from otuside any \f(CW\*(C`ev_loop\*(C'\fR calls. |
1031 | It is safe to call \f(CW\*(C`ev_break\*(C'\fR from outside any \f(CW\*(C`ev_run\*(C'\fR calls, too, in |
|
|
1032 | which case it will have no effect. |
885 | .IP "ev_ref (loop)" 4 |
1033 | .IP "ev_ref (loop)" 4 |
886 | .IX Item "ev_ref (loop)" |
1034 | .IX Item "ev_ref (loop)" |
887 | .PD 0 |
1035 | .PD 0 |
888 | .IP "ev_unref (loop)" 4 |
1036 | .IP "ev_unref (loop)" 4 |
889 | .IX Item "ev_unref (loop)" |
1037 | .IX Item "ev_unref (loop)" |
890 | .PD |
1038 | .PD |
891 | Ref/unref can be used to add or remove a reference count on the event |
1039 | Ref/unref can be used to add or remove a reference count on the event |
892 | loop: Every watcher keeps one reference, and as long as the reference |
1040 | loop: Every watcher keeps one reference, and as long as the reference |
893 | count is nonzero, \f(CW\*(C`ev_loop\*(C'\fR will not return on its own. |
1041 | count is nonzero, \f(CW\*(C`ev_run\*(C'\fR will not return on its own. |
894 | .Sp |
1042 | .Sp |
895 | If you have a watcher you never unregister that should not keep \f(CW\*(C`ev_loop\*(C'\fR |
1043 | This is useful when you have a watcher that you never intend to |
896 | from returning, call \fIev_unref()\fR after starting, and \fIev_ref()\fR before |
1044 | unregister, but that nevertheless should not keep \f(CW\*(C`ev_run\*(C'\fR from |
|
|
1045 | returning. In such a case, call \f(CW\*(C`ev_unref\*(C'\fR after starting, and \f(CW\*(C`ev_ref\*(C'\fR |
897 | stopping it. |
1046 | before stopping it. |
898 | .Sp |
1047 | .Sp |
899 | As an example, libev itself uses this for its internal signal pipe: It |
1048 | As an example, libev itself uses this for its internal signal pipe: It |
900 | is not visible to the libev user and should not keep \f(CW\*(C`ev_loop\*(C'\fR from |
1049 | is not visible to the libev user and should not keep \f(CW\*(C`ev_run\*(C'\fR from |
901 | exiting if no event watchers registered by it are active. It is also an |
1050 | exiting if no event watchers registered by it are active. It is also an |
902 | excellent way to do this for generic recurring timers or from within |
1051 | excellent way to do this for generic recurring timers or from within |
903 | third-party libraries. Just remember to \fIunref after start\fR and \fIref |
1052 | third-party libraries. Just remember to \fIunref after start\fR and \fIref |
904 | before stop\fR (but only if the watcher wasn't active before, or was active |
1053 | before stop\fR (but only if the watcher wasn't active before, or was active |
905 | before, respectively. Note also that libev might stop watchers itself |
1054 | before, respectively. Note also that libev might stop watchers itself |
906 | (e.g. non-repeating timers) in which case you have to \f(CW\*(C`ev_ref\*(C'\fR |
1055 | (e.g. non-repeating timers) in which case you have to \f(CW\*(C`ev_ref\*(C'\fR |
907 | in the callback). |
1056 | in the callback). |
908 | .Sp |
1057 | .Sp |
909 | Example: Create a signal watcher, but keep it from keeping \f(CW\*(C`ev_loop\*(C'\fR |
1058 | Example: Create a signal watcher, but keep it from keeping \f(CW\*(C`ev_run\*(C'\fR |
910 | running when nothing else is active. |
1059 | running when nothing else is active. |
911 | .Sp |
1060 | .Sp |
912 | .Vb 4 |
1061 | .Vb 4 |
913 | \& ev_signal exitsig; |
1062 | \& ev_signal exitsig; |
914 | \& ev_signal_init (&exitsig, sig_cb, SIGINT); |
1063 | \& ev_signal_init (&exitsig, sig_cb, SIGINT); |
915 | \& ev_signal_start (loop, &exitsig); |
1064 | \& ev_signal_start (loop, &exitsig); |
916 | \& evf_unref (loop); |
1065 | \& ev_unref (loop); |
917 | .Ve |
1066 | .Ve |
918 | .Sp |
1067 | .Sp |
919 | Example: For some weird reason, unregister the above signal handler again. |
1068 | Example: For some weird reason, unregister the above signal handler again. |
920 | .Sp |
1069 | .Sp |
921 | .Vb 2 |
1070 | .Vb 2 |
… | |
… | |
945 | overhead for the actual polling but can deliver many events at once. |
1094 | overhead for the actual polling but can deliver many events at once. |
946 | .Sp |
1095 | .Sp |
947 | By setting a higher \fIio collect interval\fR you allow libev to spend more |
1096 | By setting a higher \fIio collect interval\fR you allow libev to spend more |
948 | time collecting I/O events, so you can handle more events per iteration, |
1097 | time collecting I/O events, so you can handle more events per iteration, |
949 | at the cost of increasing latency. Timeouts (both \f(CW\*(C`ev_periodic\*(C'\fR and |
1098 | at the cost of increasing latency. Timeouts (both \f(CW\*(C`ev_periodic\*(C'\fR and |
950 | \&\f(CW\*(C`ev_timer\*(C'\fR) will be not affected. Setting this to a non-null value will |
1099 | \&\f(CW\*(C`ev_timer\*(C'\fR) will not be affected. Setting this to a non-null value will |
951 | introduce an additional \f(CW\*(C`ev_sleep ()\*(C'\fR call into most loop iterations. |
1100 | introduce an additional \f(CW\*(C`ev_sleep ()\*(C'\fR call into most loop iterations. The |
|
|
1101 | sleep time ensures that libev will not poll for I/O events more often then |
|
|
1102 | once per this interval, on average (as long as the host time resolution is |
|
|
1103 | good enough). |
952 | .Sp |
1104 | .Sp |
953 | Likewise, by setting a higher \fItimeout collect interval\fR you allow libev |
1105 | Likewise, by setting a higher \fItimeout collect interval\fR you allow libev |
954 | to spend more time collecting timeouts, at the expense of increased |
1106 | to spend more time collecting timeouts, at the expense of increased |
955 | latency/jitter/inexactness (the watcher callback will be called |
1107 | latency/jitter/inexactness (the watcher callback will be called |
956 | later). \f(CW\*(C`ev_io\*(C'\fR watchers will not be affected. Setting this to a non-null |
1108 | later). \f(CW\*(C`ev_io\*(C'\fR watchers will not be affected. Setting this to a non-null |
… | |
… | |
958 | .Sp |
1110 | .Sp |
959 | Many (busy) programs can usually benefit by setting the I/O collect |
1111 | Many (busy) programs can usually benefit by setting the I/O collect |
960 | interval to a value near \f(CW0.1\fR or so, which is often enough for |
1112 | interval to a value near \f(CW0.1\fR or so, which is often enough for |
961 | interactive servers (of course not for games), likewise for timeouts. It |
1113 | interactive servers (of course not for games), likewise for timeouts. It |
962 | usually doesn't make much sense to set it to a lower value than \f(CW0.01\fR, |
1114 | usually doesn't make much sense to set it to a lower value than \f(CW0.01\fR, |
963 | as this approaches the timing granularity of most systems. |
1115 | as this approaches the timing granularity of most systems. Note that if |
|
|
1116 | you do transactions with the outside world and you can't increase the |
|
|
1117 | parallelity, then this setting will limit your transaction rate (if you |
|
|
1118 | need to poll once per transaction and the I/O collect interval is 0.01, |
|
|
1119 | then you can't do more than 100 transactions per second). |
964 | .Sp |
1120 | .Sp |
965 | Setting the \fItimeout collect interval\fR can improve the opportunity for |
1121 | Setting the \fItimeout collect interval\fR can improve the opportunity for |
966 | saving power, as the program will \*(L"bundle\*(R" timer callback invocations that |
1122 | saving power, as the program will \*(L"bundle\*(R" timer callback invocations that |
967 | are \*(L"near\*(R" in time together, by delaying some, thus reducing the number of |
1123 | are \*(L"near\*(R" in time together, by delaying some, thus reducing the number of |
968 | times the process sleeps and wakes up again. Another useful technique to |
1124 | times the process sleeps and wakes up again. Another useful technique to |
969 | reduce iterations/wake\-ups is to use \f(CW\*(C`ev_periodic\*(C'\fR watchers and make sure |
1125 | reduce iterations/wake\-ups is to use \f(CW\*(C`ev_periodic\*(C'\fR watchers and make sure |
970 | they fire on, say, one-second boundaries only. |
1126 | they fire on, say, one-second boundaries only. |
|
|
1127 | .Sp |
|
|
1128 | Example: we only need 0.1s timeout granularity, and we wish not to poll |
|
|
1129 | more often than 100 times per second: |
|
|
1130 | .Sp |
|
|
1131 | .Vb 2 |
|
|
1132 | \& ev_set_timeout_collect_interval (EV_DEFAULT_UC_ 0.1); |
|
|
1133 | \& ev_set_io_collect_interval (EV_DEFAULT_UC_ 0.01); |
|
|
1134 | .Ve |
|
|
1135 | .IP "ev_invoke_pending (loop)" 4 |
|
|
1136 | .IX Item "ev_invoke_pending (loop)" |
|
|
1137 | This call will simply invoke all pending watchers while resetting their |
|
|
1138 | pending state. Normally, \f(CW\*(C`ev_run\*(C'\fR does this automatically when required, |
|
|
1139 | but when overriding the invoke callback this call comes handy. This |
|
|
1140 | function can be invoked from a watcher \- this can be useful for example |
|
|
1141 | when you want to do some lengthy calculation and want to pass further |
|
|
1142 | event handling to another thread (you still have to make sure only one |
|
|
1143 | thread executes within \f(CW\*(C`ev_invoke_pending\*(C'\fR or \f(CW\*(C`ev_run\*(C'\fR of course). |
|
|
1144 | .IP "int ev_pending_count (loop)" 4 |
|
|
1145 | .IX Item "int ev_pending_count (loop)" |
|
|
1146 | Returns the number of pending watchers \- zero indicates that no watchers |
|
|
1147 | are pending. |
|
|
1148 | .IP "ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(\s-1EV_P\s0))" 4 |
|
|
1149 | .IX Item "ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(EV_P))" |
|
|
1150 | This overrides the invoke pending functionality of the loop: Instead of |
|
|
1151 | invoking all pending watchers when there are any, \f(CW\*(C`ev_run\*(C'\fR will call |
|
|
1152 | this callback instead. This is useful, for example, when you want to |
|
|
1153 | invoke the actual watchers inside another context (another thread etc.). |
|
|
1154 | .Sp |
|
|
1155 | If you want to reset the callback, use \f(CW\*(C`ev_invoke_pending\*(C'\fR as new |
|
|
1156 | callback. |
|
|
1157 | .IP "ev_set_loop_release_cb (loop, void (*release)(\s-1EV_P\s0) throw (), void (*acquire)(\s-1EV_P\s0) throw ())" 4 |
|
|
1158 | .IX Item "ev_set_loop_release_cb (loop, void (*release)(EV_P) throw (), void (*acquire)(EV_P) throw ())" |
|
|
1159 | Sometimes you want to share the same loop between multiple threads. This |
|
|
1160 | can be done relatively simply by putting mutex_lock/unlock calls around |
|
|
1161 | each call to a libev function. |
|
|
1162 | .Sp |
|
|
1163 | However, \f(CW\*(C`ev_run\*(C'\fR can run an indefinite time, so it is not feasible |
|
|
1164 | to wait for it to return. One way around this is to wake up the event |
|
|
1165 | loop via \f(CW\*(C`ev_break\*(C'\fR and \f(CW\*(C`ev_async_send\*(C'\fR, another way is to set these |
|
|
1166 | \&\fIrelease\fR and \fIacquire\fR callbacks on the loop. |
|
|
1167 | .Sp |
|
|
1168 | When set, then \f(CW\*(C`release\*(C'\fR will be called just before the thread is |
|
|
1169 | suspended waiting for new events, and \f(CW\*(C`acquire\*(C'\fR is called just |
|
|
1170 | afterwards. |
|
|
1171 | .Sp |
|
|
1172 | Ideally, \f(CW\*(C`release\*(C'\fR will just call your mutex_unlock function, and |
|
|
1173 | \&\f(CW\*(C`acquire\*(C'\fR will just call the mutex_lock function again. |
|
|
1174 | .Sp |
|
|
1175 | While event loop modifications are allowed between invocations of |
|
|
1176 | \&\f(CW\*(C`release\*(C'\fR and \f(CW\*(C`acquire\*(C'\fR (that's their only purpose after all), no |
|
|
1177 | modifications done will affect the event loop, i.e. adding watchers will |
|
|
1178 | have no effect on the set of file descriptors being watched, or the time |
|
|
1179 | waited. Use an \f(CW\*(C`ev_async\*(C'\fR watcher to wake up \f(CW\*(C`ev_run\*(C'\fR when you want it |
|
|
1180 | to take note of any changes you made. |
|
|
1181 | .Sp |
|
|
1182 | In theory, threads executing \f(CW\*(C`ev_run\*(C'\fR will be async-cancel safe between |
|
|
1183 | invocations of \f(CW\*(C`release\*(C'\fR and \f(CW\*(C`acquire\*(C'\fR. |
|
|
1184 | .Sp |
|
|
1185 | See also the locking example in the \f(CW\*(C`THREADS\*(C'\fR section later in this |
|
|
1186 | document. |
|
|
1187 | .IP "ev_set_userdata (loop, void *data)" 4 |
|
|
1188 | .IX Item "ev_set_userdata (loop, void *data)" |
|
|
1189 | .PD 0 |
|
|
1190 | .IP "void *ev_userdata (loop)" 4 |
|
|
1191 | .IX Item "void *ev_userdata (loop)" |
|
|
1192 | .PD |
|
|
1193 | Set and retrieve a single \f(CW\*(C`void *\*(C'\fR associated with a loop. When |
|
|
1194 | \&\f(CW\*(C`ev_set_userdata\*(C'\fR has never been called, then \f(CW\*(C`ev_userdata\*(C'\fR returns |
|
|
1195 | \&\f(CW0\fR. |
|
|
1196 | .Sp |
|
|
1197 | These two functions can be used to associate arbitrary data with a loop, |
|
|
1198 | and are intended solely for the \f(CW\*(C`invoke_pending_cb\*(C'\fR, \f(CW\*(C`release\*(C'\fR and |
|
|
1199 | \&\f(CW\*(C`acquire\*(C'\fR callbacks described above, but of course can be (ab\-)used for |
|
|
1200 | any other purpose as well. |
971 | .IP "ev_loop_verify (loop)" 4 |
1201 | .IP "ev_verify (loop)" 4 |
972 | .IX Item "ev_loop_verify (loop)" |
1202 | .IX Item "ev_verify (loop)" |
973 | This function only does something when \f(CW\*(C`EV_VERIFY\*(C'\fR support has been |
1203 | This function only does something when \f(CW\*(C`EV_VERIFY\*(C'\fR support has been |
974 | compiled in, which is the default for non-minimal builds. It tries to go |
1204 | compiled in, which is the default for non-minimal builds. It tries to go |
975 | through all internal structures and checks them for validity. If anything |
1205 | through all internal structures and checks them for validity. If anything |
976 | is found to be inconsistent, it will print an error message to standard |
1206 | is found to be inconsistent, it will print an error message to standard |
977 | error and call \f(CW\*(C`abort ()\*(C'\fR. |
1207 | error and call \f(CW\*(C`abort ()\*(C'\fR. |
… | |
… | |
983 | .IX Header "ANATOMY OF A WATCHER" |
1213 | .IX Header "ANATOMY OF A WATCHER" |
984 | In the following description, uppercase \f(CW\*(C`TYPE\*(C'\fR in names stands for the |
1214 | In the following description, uppercase \f(CW\*(C`TYPE\*(C'\fR in names stands for the |
985 | watcher type, e.g. \f(CW\*(C`ev_TYPE_start\*(C'\fR can mean \f(CW\*(C`ev_timer_start\*(C'\fR for timer |
1215 | watcher type, e.g. \f(CW\*(C`ev_TYPE_start\*(C'\fR can mean \f(CW\*(C`ev_timer_start\*(C'\fR for timer |
986 | watchers and \f(CW\*(C`ev_io_start\*(C'\fR for I/O watchers. |
1216 | watchers and \f(CW\*(C`ev_io_start\*(C'\fR for I/O watchers. |
987 | .PP |
1217 | .PP |
988 | A watcher is a structure that you create and register to record your |
1218 | A watcher is an opaque structure that you allocate and register to record |
989 | interest in some event. For instance, if you want to wait for \s-1STDIN\s0 to |
1219 | your interest in some event. To make a concrete example, imagine you want |
990 | become readable, you would create an \f(CW\*(C`ev_io\*(C'\fR watcher for that: |
1220 | to wait for \s-1STDIN\s0 to become readable, you would create an \f(CW\*(C`ev_io\*(C'\fR watcher |
|
|
1221 | for that: |
991 | .PP |
1222 | .PP |
992 | .Vb 5 |
1223 | .Vb 5 |
993 | \& static void my_cb (struct ev_loop *loop, ev_io *w, int revents) |
1224 | \& static void my_cb (struct ev_loop *loop, ev_io *w, int revents) |
994 | \& { |
1225 | \& { |
995 | \& ev_io_stop (w); |
1226 | \& ev_io_stop (w); |
996 | \& ev_unloop (loop, EVUNLOOP_ALL); |
1227 | \& ev_break (loop, EVBREAK_ALL); |
997 | \& } |
1228 | \& } |
998 | \& |
1229 | \& |
999 | \& struct ev_loop *loop = ev_default_loop (0); |
1230 | \& struct ev_loop *loop = ev_default_loop (0); |
1000 | \& |
1231 | \& |
1001 | \& ev_io stdin_watcher; |
1232 | \& ev_io stdin_watcher; |
1002 | \& |
1233 | \& |
1003 | \& ev_init (&stdin_watcher, my_cb); |
1234 | \& ev_init (&stdin_watcher, my_cb); |
1004 | \& ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ); |
1235 | \& ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ); |
1005 | \& ev_io_start (loop, &stdin_watcher); |
1236 | \& ev_io_start (loop, &stdin_watcher); |
1006 | \& |
1237 | \& |
1007 | \& ev_loop (loop, 0); |
1238 | \& ev_run (loop, 0); |
1008 | .Ve |
1239 | .Ve |
1009 | .PP |
1240 | .PP |
1010 | As you can see, you are responsible for allocating the memory for your |
1241 | As you can see, you are responsible for allocating the memory for your |
1011 | watcher structures (and it is \fIusually\fR a bad idea to do this on the |
1242 | watcher structures (and it is \fIusually\fR a bad idea to do this on the |
1012 | stack). |
1243 | stack). |
1013 | .PP |
1244 | .PP |
1014 | Each watcher has an associated watcher structure (called \f(CW\*(C`struct ev_TYPE\*(C'\fR |
1245 | Each watcher has an associated watcher structure (called \f(CW\*(C`struct ev_TYPE\*(C'\fR |
1015 | or simply \f(CW\*(C`ev_TYPE\*(C'\fR, as typedefs are provided for all watcher structs). |
1246 | or simply \f(CW\*(C`ev_TYPE\*(C'\fR, as typedefs are provided for all watcher structs). |
1016 | .PP |
1247 | .PP |
1017 | Each watcher structure must be initialised by a call to \f(CW\*(C`ev_init |
1248 | Each watcher structure must be initialised by a call to \f(CW\*(C`ev_init (watcher |
1018 | (watcher *, callback)\*(C'\fR, which expects a callback to be provided. This |
1249 | *, callback)\*(C'\fR, which expects a callback to be provided. This callback is |
1019 | callback gets invoked each time the event occurs (or, in the case of I/O |
1250 | invoked each time the event occurs (or, in the case of I/O watchers, each |
1020 | watchers, each time the event loop detects that the file descriptor given |
1251 | time the event loop detects that the file descriptor given is readable |
1021 | is readable and/or writable). |
1252 | and/or writable). |
1022 | .PP |
1253 | .PP |
1023 | Each watcher type further has its own \f(CW\*(C`ev_TYPE_set (watcher *, ...)\*(C'\fR |
1254 | Each watcher type further has its own \f(CW\*(C`ev_TYPE_set (watcher *, ...)\*(C'\fR |
1024 | macro to configure it, with arguments specific to the watcher type. There |
1255 | macro to configure it, with arguments specific to the watcher type. There |
1025 | is also a macro to combine initialisation and setting in one call: \f(CW\*(C`ev_TYPE_init (watcher *, callback, ...)\*(C'\fR. |
1256 | is also a macro to combine initialisation and setting in one call: \f(CW\*(C`ev_TYPE_init (watcher *, callback, ...)\*(C'\fR. |
1026 | .PP |
1257 | .PP |
… | |
… | |
1048 | .el .IP "\f(CWEV_WRITE\fR" 4 |
1279 | .el .IP "\f(CWEV_WRITE\fR" 4 |
1049 | .IX Item "EV_WRITE" |
1280 | .IX Item "EV_WRITE" |
1050 | .PD |
1281 | .PD |
1051 | The file descriptor in the \f(CW\*(C`ev_io\*(C'\fR watcher has become readable and/or |
1282 | The file descriptor in the \f(CW\*(C`ev_io\*(C'\fR watcher has become readable and/or |
1052 | writable. |
1283 | writable. |
1053 | .ie n .IP """EV_TIMEOUT""" 4 |
1284 | .ie n .IP """EV_TIMER""" 4 |
1054 | .el .IP "\f(CWEV_TIMEOUT\fR" 4 |
1285 | .el .IP "\f(CWEV_TIMER\fR" 4 |
1055 | .IX Item "EV_TIMEOUT" |
1286 | .IX Item "EV_TIMER" |
1056 | The \f(CW\*(C`ev_timer\*(C'\fR watcher has timed out. |
1287 | The \f(CW\*(C`ev_timer\*(C'\fR watcher has timed out. |
1057 | .ie n .IP """EV_PERIODIC""" 4 |
1288 | .ie n .IP """EV_PERIODIC""" 4 |
1058 | .el .IP "\f(CWEV_PERIODIC\fR" 4 |
1289 | .el .IP "\f(CWEV_PERIODIC\fR" 4 |
1059 | .IX Item "EV_PERIODIC" |
1290 | .IX Item "EV_PERIODIC" |
1060 | The \f(CW\*(C`ev_periodic\*(C'\fR watcher has timed out. |
1291 | The \f(CW\*(C`ev_periodic\*(C'\fR watcher has timed out. |
… | |
… | |
1080 | .PD 0 |
1311 | .PD 0 |
1081 | .ie n .IP """EV_CHECK""" 4 |
1312 | .ie n .IP """EV_CHECK""" 4 |
1082 | .el .IP "\f(CWEV_CHECK\fR" 4 |
1313 | .el .IP "\f(CWEV_CHECK\fR" 4 |
1083 | .IX Item "EV_CHECK" |
1314 | .IX Item "EV_CHECK" |
1084 | .PD |
1315 | .PD |
1085 | All \f(CW\*(C`ev_prepare\*(C'\fR watchers are invoked just \fIbefore\fR \f(CW\*(C`ev_loop\*(C'\fR starts |
1316 | All \f(CW\*(C`ev_prepare\*(C'\fR watchers are invoked just \fIbefore\fR \f(CW\*(C`ev_run\*(C'\fR starts to |
1086 | to gather new events, and all \f(CW\*(C`ev_check\*(C'\fR watchers are invoked just after |
1317 | gather new events, and all \f(CW\*(C`ev_check\*(C'\fR watchers are queued (not invoked) |
1087 | \&\f(CW\*(C`ev_loop\*(C'\fR has gathered them, but before it invokes any callbacks for any |
1318 | just after \f(CW\*(C`ev_run\*(C'\fR has gathered them, but before it queues any callbacks |
|
|
1319 | for any received events. That means \f(CW\*(C`ev_prepare\*(C'\fR watchers are the last |
|
|
1320 | watchers invoked before the event loop sleeps or polls for new events, and |
|
|
1321 | \&\f(CW\*(C`ev_check\*(C'\fR watchers will be invoked before any other watchers of the same |
|
|
1322 | or lower priority within an event loop iteration. |
|
|
1323 | .Sp |
1088 | received events. Callbacks of both watcher types can start and stop as |
1324 | Callbacks of both watcher types can start and stop as many watchers as |
1089 | many watchers as they want, and all of them will be taken into account |
1325 | they want, and all of them will be taken into account (for example, a |
1090 | (for example, a \f(CW\*(C`ev_prepare\*(C'\fR watcher might start an idle watcher to keep |
1326 | \&\f(CW\*(C`ev_prepare\*(C'\fR watcher might start an idle watcher to keep \f(CW\*(C`ev_run\*(C'\fR from |
1091 | \&\f(CW\*(C`ev_loop\*(C'\fR from blocking). |
1327 | blocking). |
1092 | .ie n .IP """EV_EMBED""" 4 |
1328 | .ie n .IP """EV_EMBED""" 4 |
1093 | .el .IP "\f(CWEV_EMBED\fR" 4 |
1329 | .el .IP "\f(CWEV_EMBED\fR" 4 |
1094 | .IX Item "EV_EMBED" |
1330 | .IX Item "EV_EMBED" |
1095 | The embedded event loop specified in the \f(CW\*(C`ev_embed\*(C'\fR watcher needs attention. |
1331 | The embedded event loop specified in the \f(CW\*(C`ev_embed\*(C'\fR watcher needs attention. |
1096 | .ie n .IP """EV_FORK""" 4 |
1332 | .ie n .IP """EV_FORK""" 4 |
1097 | .el .IP "\f(CWEV_FORK\fR" 4 |
1333 | .el .IP "\f(CWEV_FORK\fR" 4 |
1098 | .IX Item "EV_FORK" |
1334 | .IX Item "EV_FORK" |
1099 | The event loop has been resumed in the child process after fork (see |
1335 | The event loop has been resumed in the child process after fork (see |
1100 | \&\f(CW\*(C`ev_fork\*(C'\fR). |
1336 | \&\f(CW\*(C`ev_fork\*(C'\fR). |
|
|
1337 | .ie n .IP """EV_CLEANUP""" 4 |
|
|
1338 | .el .IP "\f(CWEV_CLEANUP\fR" 4 |
|
|
1339 | .IX Item "EV_CLEANUP" |
|
|
1340 | The event loop is about to be destroyed (see \f(CW\*(C`ev_cleanup\*(C'\fR). |
1101 | .ie n .IP """EV_ASYNC""" 4 |
1341 | .ie n .IP """EV_ASYNC""" 4 |
1102 | .el .IP "\f(CWEV_ASYNC\fR" 4 |
1342 | .el .IP "\f(CWEV_ASYNC\fR" 4 |
1103 | .IX Item "EV_ASYNC" |
1343 | .IX Item "EV_ASYNC" |
1104 | The given async watcher has been asynchronously notified (see \f(CW\*(C`ev_async\*(C'\fR). |
1344 | The given async watcher has been asynchronously notified (see \f(CW\*(C`ev_async\*(C'\fR). |
1105 | .ie n .IP """EV_CUSTOM""" 4 |
1345 | .ie n .IP """EV_CUSTOM""" 4 |
… | |
… | |
1124 | example it might indicate that a fd is readable or writable, and if your |
1364 | example it might indicate that a fd is readable or writable, and if your |
1125 | callbacks is well-written it can just attempt the operation and cope with |
1365 | callbacks is well-written it can just attempt the operation and cope with |
1126 | the error from \fIread()\fR or \fIwrite()\fR. This will not work in multi-threaded |
1366 | the error from \fIread()\fR or \fIwrite()\fR. This will not work in multi-threaded |
1127 | programs, though, as the fd could already be closed and reused for another |
1367 | programs, though, as the fd could already be closed and reused for another |
1128 | thing, so beware. |
1368 | thing, so beware. |
1129 | .Sh "\s-1GENERIC\s0 \s-1WATCHER\s0 \s-1FUNCTIONS\s0" |
1369 | .SS "\s-1GENERIC WATCHER FUNCTIONS\s0" |
1130 | .IX Subsection "GENERIC WATCHER FUNCTIONS" |
1370 | .IX Subsection "GENERIC WATCHER FUNCTIONS" |
1131 | .ie n .IP """ev_init"" (ev_TYPE *watcher, callback)" 4 |
1371 | .ie n .IP """ev_init"" (ev_TYPE *watcher, callback)" 4 |
1132 | .el .IP "\f(CWev_init\fR (ev_TYPE *watcher, callback)" 4 |
1372 | .el .IP "\f(CWev_init\fR (ev_TYPE *watcher, callback)" 4 |
1133 | .IX Item "ev_init (ev_TYPE *watcher, callback)" |
1373 | .IX Item "ev_init (ev_TYPE *watcher, callback)" |
1134 | This macro initialises the generic portion of a watcher. The contents |
1374 | This macro initialises the generic portion of a watcher. The contents |
… | |
… | |
1149 | .Vb 3 |
1389 | .Vb 3 |
1150 | \& ev_io w; |
1390 | \& ev_io w; |
1151 | \& ev_init (&w, my_cb); |
1391 | \& ev_init (&w, my_cb); |
1152 | \& ev_io_set (&w, STDIN_FILENO, EV_READ); |
1392 | \& ev_io_set (&w, STDIN_FILENO, EV_READ); |
1153 | .Ve |
1393 | .Ve |
1154 | .ie n .IP """ev_TYPE_set"" (ev_TYPE *, [args])" 4 |
1394 | .ie n .IP """ev_TYPE_set"" (ev_TYPE *watcher, [args])" 4 |
1155 | .el .IP "\f(CWev_TYPE_set\fR (ev_TYPE *, [args])" 4 |
1395 | .el .IP "\f(CWev_TYPE_set\fR (ev_TYPE *watcher, [args])" 4 |
1156 | .IX Item "ev_TYPE_set (ev_TYPE *, [args])" |
1396 | .IX Item "ev_TYPE_set (ev_TYPE *watcher, [args])" |
1157 | This macro initialises the type-specific parts of a watcher. You need to |
1397 | This macro initialises the type-specific parts of a watcher. You need to |
1158 | call \f(CW\*(C`ev_init\*(C'\fR at least once before you call this macro, but you can |
1398 | call \f(CW\*(C`ev_init\*(C'\fR at least once before you call this macro, but you can |
1159 | call \f(CW\*(C`ev_TYPE_set\*(C'\fR any number of times. You must not, however, call this |
1399 | call \f(CW\*(C`ev_TYPE_set\*(C'\fR any number of times. You must not, however, call this |
1160 | macro on a watcher that is active (it can be pending, however, which is a |
1400 | macro on a watcher that is active (it can be pending, however, which is a |
1161 | difference to the \f(CW\*(C`ev_init\*(C'\fR macro). |
1401 | difference to the \f(CW\*(C`ev_init\*(C'\fR macro). |
… | |
… | |
1174 | Example: Initialise and set an \f(CW\*(C`ev_io\*(C'\fR watcher in one step. |
1414 | Example: Initialise and set an \f(CW\*(C`ev_io\*(C'\fR watcher in one step. |
1175 | .Sp |
1415 | .Sp |
1176 | .Vb 1 |
1416 | .Vb 1 |
1177 | \& ev_io_init (&w, my_cb, STDIN_FILENO, EV_READ); |
1417 | \& ev_io_init (&w, my_cb, STDIN_FILENO, EV_READ); |
1178 | .Ve |
1418 | .Ve |
1179 | .ie n .IP """ev_TYPE_start"" (loop *, ev_TYPE *watcher)" 4 |
1419 | .ie n .IP """ev_TYPE_start"" (loop, ev_TYPE *watcher)" 4 |
1180 | .el .IP "\f(CWev_TYPE_start\fR (loop *, ev_TYPE *watcher)" 4 |
1420 | .el .IP "\f(CWev_TYPE_start\fR (loop, ev_TYPE *watcher)" 4 |
1181 | .IX Item "ev_TYPE_start (loop *, ev_TYPE *watcher)" |
1421 | .IX Item "ev_TYPE_start (loop, ev_TYPE *watcher)" |
1182 | Starts (activates) the given watcher. Only active watchers will receive |
1422 | Starts (activates) the given watcher. Only active watchers will receive |
1183 | events. If the watcher is already active nothing will happen. |
1423 | events. If the watcher is already active nothing will happen. |
1184 | .Sp |
1424 | .Sp |
1185 | Example: Start the \f(CW\*(C`ev_io\*(C'\fR watcher that is being abused as example in this |
1425 | Example: Start the \f(CW\*(C`ev_io\*(C'\fR watcher that is being abused as example in this |
1186 | whole section. |
1426 | whole section. |
1187 | .Sp |
1427 | .Sp |
1188 | .Vb 1 |
1428 | .Vb 1 |
1189 | \& ev_io_start (EV_DEFAULT_UC, &w); |
1429 | \& ev_io_start (EV_DEFAULT_UC, &w); |
1190 | .Ve |
1430 | .Ve |
1191 | .ie n .IP """ev_TYPE_stop"" (loop *, ev_TYPE *watcher)" 4 |
1431 | .ie n .IP """ev_TYPE_stop"" (loop, ev_TYPE *watcher)" 4 |
1192 | .el .IP "\f(CWev_TYPE_stop\fR (loop *, ev_TYPE *watcher)" 4 |
1432 | .el .IP "\f(CWev_TYPE_stop\fR (loop, ev_TYPE *watcher)" 4 |
1193 | .IX Item "ev_TYPE_stop (loop *, ev_TYPE *watcher)" |
1433 | .IX Item "ev_TYPE_stop (loop, ev_TYPE *watcher)" |
1194 | Stops the given watcher if active, and clears the pending status (whether |
1434 | Stops the given watcher if active, and clears the pending status (whether |
1195 | the watcher was active or not). |
1435 | the watcher was active or not). |
1196 | .Sp |
1436 | .Sp |
1197 | It is possible that stopped watchers are pending \- for example, |
1437 | It is possible that stopped watchers are pending \- for example, |
1198 | non-repeating timers are being stopped when they become pending \- but |
1438 | non-repeating timers are being stopped when they become pending \- but |
… | |
… | |
1213 | make sure the watcher is available to libev (e.g. you cannot \f(CW\*(C`free ()\*(C'\fR |
1453 | make sure the watcher is available to libev (e.g. you cannot \f(CW\*(C`free ()\*(C'\fR |
1214 | it). |
1454 | it). |
1215 | .IP "callback ev_cb (ev_TYPE *watcher)" 4 |
1455 | .IP "callback ev_cb (ev_TYPE *watcher)" 4 |
1216 | .IX Item "callback ev_cb (ev_TYPE *watcher)" |
1456 | .IX Item "callback ev_cb (ev_TYPE *watcher)" |
1217 | Returns the callback currently set on the watcher. |
1457 | Returns the callback currently set on the watcher. |
1218 | .IP "ev_cb_set (ev_TYPE *watcher, callback)" 4 |
1458 | .IP "ev_set_cb (ev_TYPE *watcher, callback)" 4 |
1219 | .IX Item "ev_cb_set (ev_TYPE *watcher, callback)" |
1459 | .IX Item "ev_set_cb (ev_TYPE *watcher, callback)" |
1220 | Change the callback. You can change the callback at virtually any time |
1460 | Change the callback. You can change the callback at virtually any time |
1221 | (modulo threads). |
1461 | (modulo threads). |
1222 | .IP "ev_set_priority (ev_TYPE *watcher, priority)" 4 |
1462 | .IP "ev_set_priority (ev_TYPE *watcher, int priority)" 4 |
1223 | .IX Item "ev_set_priority (ev_TYPE *watcher, priority)" |
1463 | .IX Item "ev_set_priority (ev_TYPE *watcher, int priority)" |
1224 | .PD 0 |
1464 | .PD 0 |
1225 | .IP "int ev_priority (ev_TYPE *watcher)" 4 |
1465 | .IP "int ev_priority (ev_TYPE *watcher)" 4 |
1226 | .IX Item "int ev_priority (ev_TYPE *watcher)" |
1466 | .IX Item "int ev_priority (ev_TYPE *watcher)" |
1227 | .PD |
1467 | .PD |
1228 | Set and query the priority of the watcher. The priority is a small |
1468 | Set and query the priority of the watcher. The priority is a small |
… | |
… | |
1242 | or might not have been clamped to the valid range. |
1482 | or might not have been clamped to the valid range. |
1243 | .Sp |
1483 | .Sp |
1244 | The default priority used by watchers when no priority has been set is |
1484 | The default priority used by watchers when no priority has been set is |
1245 | always \f(CW0\fR, which is supposed to not be too high and not be too low :). |
1485 | always \f(CW0\fR, which is supposed to not be too high and not be too low :). |
1246 | .Sp |
1486 | .Sp |
1247 | See \*(L"\s-1WATCHER\s0 \s-1PRIORITY\s0 \s-1MODELS\s0\*(R", below, for a more thorough treatment of |
1487 | See \*(L"\s-1WATCHER PRIORITY MODELS\*(R"\s0, below, for a more thorough treatment of |
1248 | priorities. |
1488 | priorities. |
1249 | .IP "ev_invoke (loop, ev_TYPE *watcher, int revents)" 4 |
1489 | .IP "ev_invoke (loop, ev_TYPE *watcher, int revents)" 4 |
1250 | .IX Item "ev_invoke (loop, ev_TYPE *watcher, int revents)" |
1490 | .IX Item "ev_invoke (loop, ev_TYPE *watcher, int revents)" |
1251 | Invoke the \f(CW\*(C`watcher\*(C'\fR with the given \f(CW\*(C`loop\*(C'\fR and \f(CW\*(C`revents\*(C'\fR. Neither |
1491 | Invoke the \f(CW\*(C`watcher\*(C'\fR with the given \f(CW\*(C`loop\*(C'\fR and \f(CW\*(C`revents\*(C'\fR. Neither |
1252 | \&\f(CW\*(C`loop\*(C'\fR nor \f(CW\*(C`revents\*(C'\fR need to be valid as long as the watcher callback |
1492 | \&\f(CW\*(C`loop\*(C'\fR nor \f(CW\*(C`revents\*(C'\fR need to be valid as long as the watcher callback |
… | |
… | |
1258 | returns its \f(CW\*(C`revents\*(C'\fR bitset (as if its callback was invoked). If the |
1498 | returns its \f(CW\*(C`revents\*(C'\fR bitset (as if its callback was invoked). If the |
1259 | watcher isn't pending it does nothing and returns \f(CW0\fR. |
1499 | watcher isn't pending it does nothing and returns \f(CW0\fR. |
1260 | .Sp |
1500 | .Sp |
1261 | Sometimes it can be useful to \*(L"poll\*(R" a watcher instead of waiting for its |
1501 | Sometimes it can be useful to \*(L"poll\*(R" a watcher instead of waiting for its |
1262 | callback to be invoked, which can be accomplished with this function. |
1502 | callback to be invoked, which can be accomplished with this function. |
1263 | .Sh "\s-1ASSOCIATING\s0 \s-1CUSTOM\s0 \s-1DATA\s0 \s-1WITH\s0 A \s-1WATCHER\s0" |
1503 | .IP "ev_feed_event (loop, ev_TYPE *watcher, int revents)" 4 |
1264 | .IX Subsection "ASSOCIATING CUSTOM DATA WITH A WATCHER" |
1504 | .IX Item "ev_feed_event (loop, ev_TYPE *watcher, int revents)" |
1265 | Each watcher has, by default, a member \f(CW\*(C`void *data\*(C'\fR that you can change |
1505 | Feeds the given event set into the event loop, as if the specified event |
1266 | and read at any time: libev will completely ignore it. This can be used |
1506 | had happened for the specified watcher (which must be a pointer to an |
1267 | to associate arbitrary data with your watcher. If you need more data and |
1507 | initialised but not necessarily started event watcher). Obviously you must |
1268 | don't want to allocate memory and store a pointer to it in that data |
1508 | not free the watcher as long as it has pending events. |
1269 | member, you can also \*(L"subclass\*(R" the watcher type and provide your own |
1509 | .Sp |
1270 | data: |
1510 | Stopping the watcher, letting libev invoke it, or calling |
|
|
1511 | \&\f(CW\*(C`ev_clear_pending\*(C'\fR will clear the pending event, even if the watcher was |
|
|
1512 | not started in the first place. |
|
|
1513 | .Sp |
|
|
1514 | See also \f(CW\*(C`ev_feed_fd_event\*(C'\fR and \f(CW\*(C`ev_feed_signal_event\*(C'\fR for related |
|
|
1515 | functions that do not need a watcher. |
1271 | .PP |
1516 | .PP |
1272 | .Vb 7 |
1517 | See also the \*(L"\s-1ASSOCIATING CUSTOM DATA WITH A WATCHER\*(R"\s0 and \*(L"\s-1BUILDING YOUR |
1273 | \& struct my_io |
1518 | OWN COMPOSITE WATCHERS\*(R"\s0 idioms. |
1274 | \& { |
1519 | .SS "\s-1WATCHER STATES\s0" |
1275 | \& ev_io io; |
1520 | .IX Subsection "WATCHER STATES" |
1276 | \& int otherfd; |
1521 | There are various watcher states mentioned throughout this manual \- |
1277 | \& void *somedata; |
1522 | active, pending and so on. In this section these states and the rules to |
1278 | \& struct whatever *mostinteresting; |
1523 | transition between them will be described in more detail \- and while these |
1279 | \& }; |
1524 | rules might look complicated, they usually do \*(L"the right thing\*(R". |
1280 | \& |
1525 | .IP "initialised" 4 |
1281 | \& ... |
1526 | .IX Item "initialised" |
1282 | \& struct my_io w; |
1527 | Before a watcher can be registered with the event loop it has to be |
1283 | \& ev_io_init (&w.io, my_cb, fd, EV_READ); |
1528 | initialised. This can be done with a call to \f(CW\*(C`ev_TYPE_init\*(C'\fR, or calls to |
1284 | .Ve |
1529 | \&\f(CW\*(C`ev_init\*(C'\fR followed by the watcher-specific \f(CW\*(C`ev_TYPE_set\*(C'\fR function. |
1285 | .PP |
1530 | .Sp |
1286 | And since your callback will be called with a pointer to the watcher, you |
1531 | In this state it is simply some block of memory that is suitable for |
1287 | can cast it back to your own type: |
1532 | use in an event loop. It can be moved around, freed, reused etc. at |
1288 | .PP |
1533 | will \- as long as you either keep the memory contents intact, or call |
1289 | .Vb 5 |
1534 | \&\f(CW\*(C`ev_TYPE_init\*(C'\fR again. |
1290 | \& static void my_cb (struct ev_loop *loop, ev_io *w_, int revents) |
1535 | .IP "started/running/active" 4 |
1291 | \& { |
1536 | .IX Item "started/running/active" |
1292 | \& struct my_io *w = (struct my_io *)w_; |
1537 | Once a watcher has been started with a call to \f(CW\*(C`ev_TYPE_start\*(C'\fR it becomes |
1293 | \& ... |
1538 | property of the event loop, and is actively waiting for events. While in |
1294 | \& } |
1539 | this state it cannot be accessed (except in a few documented ways), moved, |
1295 | .Ve |
1540 | freed or anything else \- the only legal thing is to keep a pointer to it, |
1296 | .PP |
1541 | and call libev functions on it that are documented to work on active watchers. |
1297 | More interesting and less C\-conformant ways of casting your callback type |
1542 | .IP "pending" 4 |
1298 | instead have been omitted. |
1543 | .IX Item "pending" |
1299 | .PP |
1544 | If a watcher is active and libev determines that an event it is interested |
1300 | Another common scenario is to use some data structure with multiple |
1545 | in has occurred (such as a timer expiring), it will become pending. It will |
1301 | embedded watchers: |
1546 | stay in this pending state until either it is stopped or its callback is |
1302 | .PP |
1547 | about to be invoked, so it is not normally pending inside the watcher |
1303 | .Vb 6 |
1548 | callback. |
1304 | \& struct my_biggy |
1549 | .Sp |
1305 | \& { |
1550 | The watcher might or might not be active while it is pending (for example, |
1306 | \& int some_data; |
1551 | an expired non-repeating timer can be pending but no longer active). If it |
1307 | \& ev_timer t1; |
1552 | is stopped, it can be freely accessed (e.g. by calling \f(CW\*(C`ev_TYPE_set\*(C'\fR), |
1308 | \& ev_timer t2; |
1553 | but it is still property of the event loop at this time, so cannot be |
1309 | \& } |
1554 | moved, freed or reused. And if it is active the rules described in the |
1310 | .Ve |
1555 | previous item still apply. |
1311 | .PP |
1556 | .Sp |
1312 | In this case getting the pointer to \f(CW\*(C`my_biggy\*(C'\fR is a bit more |
1557 | It is also possible to feed an event on a watcher that is not active (e.g. |
1313 | complicated: Either you store the address of your \f(CW\*(C`my_biggy\*(C'\fR struct |
1558 | via \f(CW\*(C`ev_feed_event\*(C'\fR), in which case it becomes pending without being |
1314 | in the \f(CW\*(C`data\*(C'\fR member of the watcher (for woozies), or you need to use |
1559 | active. |
1315 | some pointer arithmetic using \f(CW\*(C`offsetof\*(C'\fR inside your watchers (for real |
1560 | .IP "stopped" 4 |
1316 | programmers): |
1561 | .IX Item "stopped" |
1317 | .PP |
1562 | A watcher can be stopped implicitly by libev (in which case it might still |
1318 | .Vb 1 |
1563 | be pending), or explicitly by calling its \f(CW\*(C`ev_TYPE_stop\*(C'\fR function. The |
1319 | \& #include <stddef.h> |
1564 | latter will clear any pending state the watcher might be in, regardless |
1320 | \& |
1565 | of whether it was active or not, so stopping a watcher explicitly before |
1321 | \& static void |
1566 | freeing it is often a good idea. |
1322 | \& t1_cb (EV_P_ ev_timer *w, int revents) |
1567 | .Sp |
1323 | \& { |
1568 | While stopped (and not pending) the watcher is essentially in the |
1324 | \& struct my_biggy big = (struct my_biggy * |
1569 | initialised state, that is, it can be reused, moved, modified in any way |
1325 | \& (((char *)w) \- offsetof (struct my_biggy, t1)); |
1570 | you wish (but when you trash the memory block, you need to \f(CW\*(C`ev_TYPE_init\*(C'\fR |
1326 | \& } |
1571 | it again). |
1327 | \& |
|
|
1328 | \& static void |
|
|
1329 | \& t2_cb (EV_P_ ev_timer *w, int revents) |
|
|
1330 | \& { |
|
|
1331 | \& struct my_biggy big = (struct my_biggy * |
|
|
1332 | \& (((char *)w) \- offsetof (struct my_biggy, t2)); |
|
|
1333 | \& } |
|
|
1334 | .Ve |
|
|
1335 | .Sh "\s-1WATCHER\s0 \s-1PRIORITY\s0 \s-1MODELS\s0" |
1572 | .SS "\s-1WATCHER PRIORITY MODELS\s0" |
1336 | .IX Subsection "WATCHER PRIORITY MODELS" |
1573 | .IX Subsection "WATCHER PRIORITY MODELS" |
1337 | Many event loops support \fIwatcher priorities\fR, which are usually small |
1574 | Many event loops support \fIwatcher priorities\fR, which are usually small |
1338 | integers that influence the ordering of event callback invocation |
1575 | integers that influence the ordering of event callback invocation |
1339 | between watchers in some way, all else being equal. |
1576 | between watchers in some way, all else being equal. |
1340 | .PP |
1577 | .PP |
… | |
… | |
1381 | .PP |
1618 | .PP |
1382 | For example, to emulate how many other event libraries handle priorities, |
1619 | For example, to emulate how many other event libraries handle priorities, |
1383 | you can associate an \f(CW\*(C`ev_idle\*(C'\fR watcher to each such watcher, and in |
1620 | you can associate an \f(CW\*(C`ev_idle\*(C'\fR watcher to each such watcher, and in |
1384 | the normal watcher callback, you just start the idle watcher. The real |
1621 | the normal watcher callback, you just start the idle watcher. The real |
1385 | processing is done in the idle watcher callback. This causes libev to |
1622 | processing is done in the idle watcher callback. This causes libev to |
1386 | continously poll and process kernel event data for the watcher, but when |
1623 | continuously poll and process kernel event data for the watcher, but when |
1387 | the lock-out case is known to be rare (which in turn is rare :), this is |
1624 | the lock-out case is known to be rare (which in turn is rare :), this is |
1388 | workable. |
1625 | workable. |
1389 | .PP |
1626 | .PP |
1390 | Usually, however, the lock-out model implemented that way will perform |
1627 | Usually, however, the lock-out model implemented that way will perform |
1391 | miserably under the type of load it was designed to handle. In that case, |
1628 | miserably under the type of load it was designed to handle. In that case, |
… | |
… | |
1406 | \& { |
1643 | \& { |
1407 | \& // stop the I/O watcher, we received the event, but |
1644 | \& // stop the I/O watcher, we received the event, but |
1408 | \& // are not yet ready to handle it. |
1645 | \& // are not yet ready to handle it. |
1409 | \& ev_io_stop (EV_A_ w); |
1646 | \& ev_io_stop (EV_A_ w); |
1410 | \& |
1647 | \& |
1411 | \& // start the idle watcher to ahndle the actual event. |
1648 | \& // start the idle watcher to handle the actual event. |
1412 | \& // it will not be executed as long as other watchers |
1649 | \& // it will not be executed as long as other watchers |
1413 | \& // with the default priority are receiving events. |
1650 | \& // with the default priority are receiving events. |
1414 | \& ev_idle_start (EV_A_ &idle); |
1651 | \& ev_idle_start (EV_A_ &idle); |
1415 | \& } |
1652 | \& } |
1416 | \& |
1653 | \& |
1417 | \& static void |
1654 | \& static void |
1418 | \& idle\-cb (EV_P_ ev_idle *w, int revents) |
1655 | \& idle_cb (EV_P_ ev_idle *w, int revents) |
1419 | \& { |
1656 | \& { |
1420 | \& // actual processing |
1657 | \& // actual processing |
1421 | \& read (STDIN_FILENO, ...); |
1658 | \& read (STDIN_FILENO, ...); |
1422 | \& |
1659 | \& |
1423 | \& // have to start the I/O watcher again, as |
1660 | \& // have to start the I/O watcher again, as |
… | |
… | |
1448 | watcher is stopped to your hearts content), or \fI[read\-write]\fR, which |
1685 | watcher is stopped to your hearts content), or \fI[read\-write]\fR, which |
1449 | means you can expect it to have some sensible content while the watcher |
1686 | means you can expect it to have some sensible content while the watcher |
1450 | is active, but you can also modify it. Modifying it may not do something |
1687 | is active, but you can also modify it. Modifying it may not do something |
1451 | sensible or take immediate effect (or do anything at all), but libev will |
1688 | sensible or take immediate effect (or do anything at all), but libev will |
1452 | not crash or malfunction in any way. |
1689 | not crash or malfunction in any way. |
1453 | .ie n .Sh """ev_io"" \- is this file descriptor readable or writable?" |
1690 | .ie n .SS """ev_io"" \- is this file descriptor readable or writable?" |
1454 | .el .Sh "\f(CWev_io\fP \- is this file descriptor readable or writable?" |
1691 | .el .SS "\f(CWev_io\fP \- is this file descriptor readable or writable?" |
1455 | .IX Subsection "ev_io - is this file descriptor readable or writable?" |
1692 | .IX Subsection "ev_io - is this file descriptor readable or writable?" |
1456 | I/O watchers check whether a file descriptor is readable or writable |
1693 | I/O watchers check whether a file descriptor is readable or writable |
1457 | in each iteration of the event loop, or, more precisely, when reading |
1694 | in each iteration of the event loop, or, more precisely, when reading |
1458 | would not block the process and writing would at least be able to write |
1695 | would not block the process and writing would at least be able to write |
1459 | some data. This behaviour is called level-triggering because you keep |
1696 | some data. This behaviour is called level-triggering because you keep |
… | |
… | |
1464 | In general you can register as many read and/or write event watchers per |
1701 | In general you can register as many read and/or write event watchers per |
1465 | fd as you want (as long as you don't confuse yourself). Setting all file |
1702 | fd as you want (as long as you don't confuse yourself). Setting all file |
1466 | descriptors to non-blocking mode is also usually a good idea (but not |
1703 | descriptors to non-blocking mode is also usually a good idea (but not |
1467 | required if you know what you are doing). |
1704 | required if you know what you are doing). |
1468 | .PP |
1705 | .PP |
1469 | If you cannot use non-blocking mode, then force the use of a |
|
|
1470 | known-to-be-good backend (at the time of this writing, this includes only |
|
|
1471 | \&\f(CW\*(C`EVBACKEND_SELECT\*(C'\fR and \f(CW\*(C`EVBACKEND_POLL\*(C'\fR). The same applies to file |
|
|
1472 | descriptors for which non-blocking operation makes no sense (such as |
|
|
1473 | files) \- libev doesn't guarentee any specific behaviour in that case. |
|
|
1474 | .PP |
|
|
1475 | Another thing you have to watch out for is that it is quite easy to |
1706 | Another thing you have to watch out for is that it is quite easy to |
1476 | receive \*(L"spurious\*(R" readiness notifications, that is your callback might |
1707 | receive \*(L"spurious\*(R" readiness notifications, that is, your callback might |
1477 | be called with \f(CW\*(C`EV_READ\*(C'\fR but a subsequent \f(CW\*(C`read\*(C'\fR(2) will actually block |
1708 | be called with \f(CW\*(C`EV_READ\*(C'\fR but a subsequent \f(CW\*(C`read\*(C'\fR(2) will actually block |
1478 | because there is no data. Not only are some backends known to create a |
1709 | because there is no data. It is very easy to get into this situation even |
1479 | lot of those (for example Solaris ports), it is very easy to get into |
1710 | with a relatively standard program structure. Thus it is best to always |
1480 | this situation even with a relatively standard program structure. Thus |
1711 | use non-blocking I/O: An extra \f(CW\*(C`read\*(C'\fR(2) returning \f(CW\*(C`EAGAIN\*(C'\fR is far |
1481 | it is best to always use non-blocking I/O: An extra \f(CW\*(C`read\*(C'\fR(2) returning |
|
|
1482 | \&\f(CW\*(C`EAGAIN\*(C'\fR is far preferable to a program hanging until some data arrives. |
1712 | preferable to a program hanging until some data arrives. |
1483 | .PP |
1713 | .PP |
1484 | If you cannot run the fd in non-blocking mode (for example you should |
1714 | If you cannot run the fd in non-blocking mode (for example you should |
1485 | not play around with an Xlib connection), then you have to separately |
1715 | not play around with an Xlib connection), then you have to separately |
1486 | re-test whether a file descriptor is really ready with a known-to-be good |
1716 | re-test whether a file descriptor is really ready with a known-to-be good |
1487 | interface such as poll (fortunately in our Xlib example, Xlib already |
1717 | interface such as poll (fortunately in the case of Xlib, it already does |
1488 | does this on its own, so its quite safe to use). Some people additionally |
1718 | this on its own, so its quite safe to use). Some people additionally |
1489 | use \f(CW\*(C`SIGALRM\*(C'\fR and an interval timer, just to be sure you won't block |
1719 | use \f(CW\*(C`SIGALRM\*(C'\fR and an interval timer, just to be sure you won't block |
1490 | indefinitely. |
1720 | indefinitely. |
1491 | .PP |
1721 | .PP |
1492 | But really, best use non-blocking mode. |
1722 | But really, best use non-blocking mode. |
1493 | .PP |
1723 | .PP |
… | |
… | |
1523 | .PP |
1753 | .PP |
1524 | There is no workaround possible except not registering events |
1754 | There is no workaround possible except not registering events |
1525 | for potentially \f(CW\*(C`dup ()\*(C'\fR'ed file descriptors, or to resort to |
1755 | for potentially \f(CW\*(C`dup ()\*(C'\fR'ed file descriptors, or to resort to |
1526 | \&\f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or \f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
1756 | \&\f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or \f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
1527 | .PP |
1757 | .PP |
|
|
1758 | \fIThe special problem of files\fR |
|
|
1759 | .IX Subsection "The special problem of files" |
|
|
1760 | .PP |
|
|
1761 | Many people try to use \f(CW\*(C`select\*(C'\fR (or libev) on file descriptors |
|
|
1762 | representing files, and expect it to become ready when their program |
|
|
1763 | doesn't block on disk accesses (which can take a long time on their own). |
|
|
1764 | .PP |
|
|
1765 | However, this cannot ever work in the \*(L"expected\*(R" way \- you get a readiness |
|
|
1766 | notification as soon as the kernel knows whether and how much data is |
|
|
1767 | there, and in the case of open files, that's always the case, so you |
|
|
1768 | always get a readiness notification instantly, and your read (or possibly |
|
|
1769 | write) will still block on the disk I/O. |
|
|
1770 | .PP |
|
|
1771 | Another way to view it is that in the case of sockets, pipes, character |
|
|
1772 | devices and so on, there is another party (the sender) that delivers data |
|
|
1773 | on its own, but in the case of files, there is no such thing: the disk |
|
|
1774 | will not send data on its own, simply because it doesn't know what you |
|
|
1775 | wish to read \- you would first have to request some data. |
|
|
1776 | .PP |
|
|
1777 | Since files are typically not-so-well supported by advanced notification |
|
|
1778 | mechanism, libev tries hard to emulate \s-1POSIX\s0 behaviour with respect |
|
|
1779 | to files, even though you should not use it. The reason for this is |
|
|
1780 | convenience: sometimes you want to watch \s-1STDIN\s0 or \s-1STDOUT,\s0 which is |
|
|
1781 | usually a tty, often a pipe, but also sometimes files or special devices |
|
|
1782 | (for example, \f(CW\*(C`epoll\*(C'\fR on Linux works with \fI/dev/random\fR but not with |
|
|
1783 | \&\fI/dev/urandom\fR), and even though the file might better be served with |
|
|
1784 | asynchronous I/O instead of with non-blocking I/O, it is still useful when |
|
|
1785 | it \*(L"just works\*(R" instead of freezing. |
|
|
1786 | .PP |
|
|
1787 | So avoid file descriptors pointing to files when you know it (e.g. use |
|
|
1788 | libeio), but use them when it is convenient, e.g. for \s-1STDIN/STDOUT,\s0 or |
|
|
1789 | when you rarely read from a file instead of from a socket, and want to |
|
|
1790 | reuse the same code path. |
|
|
1791 | .PP |
1528 | \fIThe special problem of fork\fR |
1792 | \fIThe special problem of fork\fR |
1529 | .IX Subsection "The special problem of fork" |
1793 | .IX Subsection "The special problem of fork" |
1530 | .PP |
1794 | .PP |
1531 | Some backends (epoll, kqueue) do not support \f(CW\*(C`fork ()\*(C'\fR at all or exhibit |
1795 | Some backends (epoll, kqueue) do not support \f(CW\*(C`fork ()\*(C'\fR at all or exhibit |
1532 | useless behaviour. Libev fully supports fork, but needs to be told about |
1796 | useless behaviour. Libev fully supports fork, but needs to be told about |
1533 | it in the child. |
1797 | it in the child if you want to continue to use it in the child. |
1534 | .PP |
1798 | .PP |
1535 | To support fork in your programs, you either have to call |
1799 | To support fork in your child processes, you have to call \f(CW\*(C`ev_loop_fork |
1536 | \&\f(CW\*(C`ev_default_fork ()\*(C'\fR or \f(CW\*(C`ev_loop_fork ()\*(C'\fR after a fork in the child, |
1800 | ()\*(C'\fR after a fork in the child, enable \f(CW\*(C`EVFLAG_FORKCHECK\*(C'\fR, or resort to |
1537 | enable \f(CW\*(C`EVFLAG_FORKCHECK\*(C'\fR, or resort to \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or |
1801 | \&\f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or \f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
1538 | \&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
|
|
1539 | .PP |
1802 | .PP |
1540 | \fIThe special problem of \s-1SIGPIPE\s0\fR |
1803 | \fIThe special problem of \s-1SIGPIPE\s0\fR |
1541 | .IX Subsection "The special problem of SIGPIPE" |
1804 | .IX Subsection "The special problem of SIGPIPE" |
1542 | .PP |
1805 | .PP |
1543 | While not really specific to libev, it is easy to forget about \f(CW\*(C`SIGPIPE\*(C'\fR: |
1806 | While not really specific to libev, it is easy to forget about \f(CW\*(C`SIGPIPE\*(C'\fR: |
1544 | when writing to a pipe whose other end has been closed, your program gets |
1807 | when writing to a pipe whose other end has been closed, your program gets |
1545 | sent a \s-1SIGPIPE\s0, which, by default, aborts your program. For most programs |
1808 | sent a \s-1SIGPIPE,\s0 which, by default, aborts your program. For most programs |
1546 | this is sensible behaviour, for daemons, this is usually undesirable. |
1809 | this is sensible behaviour, for daemons, this is usually undesirable. |
1547 | .PP |
1810 | .PP |
1548 | So when you encounter spurious, unexplained daemon exits, make sure you |
1811 | So when you encounter spurious, unexplained daemon exits, make sure you |
1549 | ignore \s-1SIGPIPE\s0 (and maybe make sure you log the exit status of your daemon |
1812 | ignore \s-1SIGPIPE \s0(and maybe make sure you log the exit status of your daemon |
1550 | somewhere, as that would have given you a big clue). |
1813 | somewhere, as that would have given you a big clue). |
|
|
1814 | .PP |
|
|
1815 | \fIThe special problem of \fIaccept()\fIing when you can't\fR |
|
|
1816 | .IX Subsection "The special problem of accept()ing when you can't" |
|
|
1817 | .PP |
|
|
1818 | Many implementations of the \s-1POSIX \s0\f(CW\*(C`accept\*(C'\fR function (for example, |
|
|
1819 | found in post\-2004 Linux) have the peculiar behaviour of not removing a |
|
|
1820 | connection from the pending queue in all error cases. |
|
|
1821 | .PP |
|
|
1822 | For example, larger servers often run out of file descriptors (because |
|
|
1823 | of resource limits), causing \f(CW\*(C`accept\*(C'\fR to fail with \f(CW\*(C`ENFILE\*(C'\fR but not |
|
|
1824 | rejecting the connection, leading to libev signalling readiness on |
|
|
1825 | the next iteration again (the connection still exists after all), and |
|
|
1826 | typically causing the program to loop at 100% \s-1CPU\s0 usage. |
|
|
1827 | .PP |
|
|
1828 | Unfortunately, the set of errors that cause this issue differs between |
|
|
1829 | operating systems, there is usually little the app can do to remedy the |
|
|
1830 | situation, and no known thread-safe method of removing the connection to |
|
|
1831 | cope with overload is known (to me). |
|
|
1832 | .PP |
|
|
1833 | One of the easiest ways to handle this situation is to just ignore it |
|
|
1834 | \&\- when the program encounters an overload, it will just loop until the |
|
|
1835 | situation is over. While this is a form of busy waiting, no \s-1OS\s0 offers an |
|
|
1836 | event-based way to handle this situation, so it's the best one can do. |
|
|
1837 | .PP |
|
|
1838 | A better way to handle the situation is to log any errors other than |
|
|
1839 | \&\f(CW\*(C`EAGAIN\*(C'\fR and \f(CW\*(C`EWOULDBLOCK\*(C'\fR, making sure not to flood the log with such |
|
|
1840 | messages, and continue as usual, which at least gives the user an idea of |
|
|
1841 | what could be wrong (\*(L"raise the ulimit!\*(R"). For extra points one could stop |
|
|
1842 | the \f(CW\*(C`ev_io\*(C'\fR watcher on the listening fd \*(L"for a while\*(R", which reduces \s-1CPU\s0 |
|
|
1843 | usage. |
|
|
1844 | .PP |
|
|
1845 | If your program is single-threaded, then you could also keep a dummy file |
|
|
1846 | descriptor for overload situations (e.g. by opening \fI/dev/null\fR), and |
|
|
1847 | when you run into \f(CW\*(C`ENFILE\*(C'\fR or \f(CW\*(C`EMFILE\*(C'\fR, close it, run \f(CW\*(C`accept\*(C'\fR, |
|
|
1848 | close that fd, and create a new dummy fd. This will gracefully refuse |
|
|
1849 | clients under typical overload conditions. |
|
|
1850 | .PP |
|
|
1851 | The last way to handle it is to simply log the error and \f(CW\*(C`exit\*(C'\fR, as |
|
|
1852 | is often done with \f(CW\*(C`malloc\*(C'\fR failures, but this results in an easy |
|
|
1853 | opportunity for a DoS attack. |
1551 | .PP |
1854 | .PP |
1552 | \fIWatcher-Specific Functions\fR |
1855 | \fIWatcher-Specific Functions\fR |
1553 | .IX Subsection "Watcher-Specific Functions" |
1856 | .IX Subsection "Watcher-Specific Functions" |
1554 | .IP "ev_io_init (ev_io *, callback, int fd, int events)" 4 |
1857 | .IP "ev_io_init (ev_io *, callback, int fd, int events)" 4 |
1555 | .IX Item "ev_io_init (ev_io *, callback, int fd, int events)" |
1858 | .IX Item "ev_io_init (ev_io *, callback, int fd, int events)" |
… | |
… | |
1585 | \& ... |
1888 | \& ... |
1586 | \& struct ev_loop *loop = ev_default_init (0); |
1889 | \& struct ev_loop *loop = ev_default_init (0); |
1587 | \& ev_io stdin_readable; |
1890 | \& ev_io stdin_readable; |
1588 | \& ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ); |
1891 | \& ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ); |
1589 | \& ev_io_start (loop, &stdin_readable); |
1892 | \& ev_io_start (loop, &stdin_readable); |
1590 | \& ev_loop (loop, 0); |
1893 | \& ev_run (loop, 0); |
1591 | .Ve |
1894 | .Ve |
1592 | .ie n .Sh """ev_timer"" \- relative and optionally repeating timeouts" |
1895 | .ie n .SS """ev_timer"" \- relative and optionally repeating timeouts" |
1593 | .el .Sh "\f(CWev_timer\fP \- relative and optionally repeating timeouts" |
1896 | .el .SS "\f(CWev_timer\fP \- relative and optionally repeating timeouts" |
1594 | .IX Subsection "ev_timer - relative and optionally repeating timeouts" |
1897 | .IX Subsection "ev_timer - relative and optionally repeating timeouts" |
1595 | Timer watchers are simple relative timers that generate an event after a |
1898 | Timer watchers are simple relative timers that generate an event after a |
1596 | given time, and optionally repeating in regular intervals after that. |
1899 | given time, and optionally repeating in regular intervals after that. |
1597 | .PP |
1900 | .PP |
1598 | The timers are based on real time, that is, if you register an event that |
1901 | The timers are based on real time, that is, if you register an event that |
… | |
… | |
1601 | detecting time jumps is hard, and some inaccuracies are unavoidable (the |
1904 | detecting time jumps is hard, and some inaccuracies are unavoidable (the |
1602 | monotonic clock option helps a lot here). |
1905 | monotonic clock option helps a lot here). |
1603 | .PP |
1906 | .PP |
1604 | The callback is guaranteed to be invoked only \fIafter\fR its timeout has |
1907 | The callback is guaranteed to be invoked only \fIafter\fR its timeout has |
1605 | passed (not \fIat\fR, so on systems with very low-resolution clocks this |
1908 | passed (not \fIat\fR, so on systems with very low-resolution clocks this |
1606 | might introduce a small delay). If multiple timers become ready during the |
1909 | might introduce a small delay, see \*(L"the special problem of being too |
|
|
1910 | early\*(R", below). If multiple timers become ready during the same loop |
1607 | same loop iteration then the ones with earlier time-out values are invoked |
1911 | iteration then the ones with earlier time-out values are invoked before |
1608 | before ones with later time-out values (but this is no longer true when a |
1912 | ones of the same priority with later time-out values (but this is no |
1609 | callback calls \f(CW\*(C`ev_loop\*(C'\fR recursively). |
1913 | longer true when a callback calls \f(CW\*(C`ev_run\*(C'\fR recursively). |
1610 | .PP |
1914 | .PP |
1611 | \fIBe smart about timeouts\fR |
1915 | \fIBe smart about timeouts\fR |
1612 | .IX Subsection "Be smart about timeouts" |
1916 | .IX Subsection "Be smart about timeouts" |
1613 | .PP |
1917 | .PP |
1614 | Many real-world problems involve some kind of timeout, usually for error |
1918 | Many real-world problems involve some kind of timeout, usually for error |
… | |
… | |
1661 | member and \f(CW\*(C`ev_timer_again\*(C'\fR. |
1965 | member and \f(CW\*(C`ev_timer_again\*(C'\fR. |
1662 | .Sp |
1966 | .Sp |
1663 | At start: |
1967 | At start: |
1664 | .Sp |
1968 | .Sp |
1665 | .Vb 3 |
1969 | .Vb 3 |
1666 | \& ev_timer_init (timer, callback); |
1970 | \& ev_init (timer, callback); |
1667 | \& timer\->repeat = 60.; |
1971 | \& timer\->repeat = 60.; |
1668 | \& ev_timer_again (loop, timer); |
1972 | \& ev_timer_again (loop, timer); |
1669 | .Ve |
1973 | .Ve |
1670 | .Sp |
1974 | .Sp |
1671 | Each time there is some activity: |
1975 | Each time there is some activity: |
… | |
… | |
1696 | .Sp |
2000 | .Sp |
1697 | In this case, it would be more efficient to leave the \f(CW\*(C`ev_timer\*(C'\fR alone, |
2001 | In this case, it would be more efficient to leave the \f(CW\*(C`ev_timer\*(C'\fR alone, |
1698 | but remember the time of last activity, and check for a real timeout only |
2002 | but remember the time of last activity, and check for a real timeout only |
1699 | within the callback: |
2003 | within the callback: |
1700 | .Sp |
2004 | .Sp |
1701 | .Vb 1 |
2005 | .Vb 3 |
|
|
2006 | \& ev_tstamp timeout = 60.; |
1702 | \& ev_tstamp last_activity; // time of last activity |
2007 | \& ev_tstamp last_activity; // time of last activity |
|
|
2008 | \& ev_timer timer; |
1703 | \& |
2009 | \& |
1704 | \& static void |
2010 | \& static void |
1705 | \& callback (EV_P_ ev_timer *w, int revents) |
2011 | \& callback (EV_P_ ev_timer *w, int revents) |
1706 | \& { |
2012 | \& { |
1707 | \& ev_tstamp now = ev_now (EV_A); |
2013 | \& // calculate when the timeout would happen |
1708 | \& ev_tstamp timeout = last_activity + 60.; |
2014 | \& ev_tstamp after = last_activity \- ev_now (EV_A) + timeout; |
1709 | \& |
2015 | \& |
1710 | \& // if last_activity + 60. is older than now, we did time out |
2016 | \& // if negative, it means we the timeout already occurred |
1711 | \& if (timeout < now) |
2017 | \& if (after < 0.) |
1712 | \& { |
2018 | \& { |
1713 | \& // timeout occured, take action |
2019 | \& // timeout occurred, take action |
1714 | \& } |
2020 | \& } |
1715 | \& else |
2021 | \& else |
1716 | \& { |
2022 | \& { |
1717 | \& // callback was invoked, but there was some activity, re\-arm |
2023 | \& // callback was invoked, but there was some recent |
1718 | \& // the watcher to fire in last_activity + 60, which is |
2024 | \& // activity. simply restart the timer to time out |
1719 | \& // guaranteed to be in the future, so "again" is positive: |
2025 | \& // after "after" seconds, which is the earliest time |
1720 | \& w\->repeat = timeout \- now; |
2026 | \& // the timeout can occur. |
|
|
2027 | \& ev_timer_set (w, after, 0.); |
1721 | \& ev_timer_again (EV_A_ w); |
2028 | \& ev_timer_start (EV_A_ w); |
1722 | \& } |
2029 | \& } |
1723 | \& } |
2030 | \& } |
1724 | .Ve |
2031 | .Ve |
1725 | .Sp |
2032 | .Sp |
1726 | To summarise the callback: first calculate the real timeout (defined |
2033 | To summarise the callback: first calculate in how many seconds the |
1727 | as \*(L"60 seconds after the last activity\*(R"), then check if that time has |
2034 | timeout will occur (by calculating the absolute time when it would occur, |
1728 | been reached, which means something \fIdid\fR, in fact, time out. Otherwise |
2035 | \&\f(CW\*(C`last_activity + timeout\*(C'\fR, and subtracting the current time, \f(CW\*(C`ev_now |
1729 | the callback was invoked too early (\f(CW\*(C`timeout\*(C'\fR is in the future), so |
2036 | (EV_A)\*(C'\fR from that). |
1730 | re-schedule the timer to fire at that future time, to see if maybe we have |
|
|
1731 | a timeout then. |
|
|
1732 | .Sp |
2037 | .Sp |
1733 | Note how \f(CW\*(C`ev_timer_again\*(C'\fR is used, taking advantage of the |
2038 | If this value is negative, then we are already past the timeout, i.e. we |
1734 | \&\f(CW\*(C`ev_timer_again\*(C'\fR optimisation when the timer is already running. |
2039 | timed out, and need to do whatever is needed in this case. |
|
|
2040 | .Sp |
|
|
2041 | Otherwise, we now the earliest time at which the timeout would trigger, |
|
|
2042 | and simply start the timer with this timeout value. |
|
|
2043 | .Sp |
|
|
2044 | In other words, each time the callback is invoked it will check whether |
|
|
2045 | the timeout occurred. If not, it will simply reschedule itself to check |
|
|
2046 | again at the earliest time it could time out. Rinse. Repeat. |
1735 | .Sp |
2047 | .Sp |
1736 | This scheme causes more callback invocations (about one every 60 seconds |
2048 | This scheme causes more callback invocations (about one every 60 seconds |
1737 | minus half the average time between activity), but virtually no calls to |
2049 | minus half the average time between activity), but virtually no calls to |
1738 | libev to change the timeout. |
2050 | libev to change the timeout. |
1739 | .Sp |
2051 | .Sp |
1740 | To start the timer, simply initialise the watcher and set \f(CW\*(C`last_activity\*(C'\fR |
2052 | To start the machinery, simply initialise the watcher and set |
1741 | to the current time (meaning we just have some activity :), then call the |
2053 | \&\f(CW\*(C`last_activity\*(C'\fR to the current time (meaning there was some activity just |
1742 | callback, which will \*(L"do the right thing\*(R" and start the timer: |
2054 | now), then call the callback, which will \*(L"do the right thing\*(R" and start |
|
|
2055 | the timer: |
1743 | .Sp |
2056 | .Sp |
1744 | .Vb 3 |
2057 | .Vb 3 |
|
|
2058 | \& last_activity = ev_now (EV_A); |
1745 | \& ev_timer_init (timer, callback); |
2059 | \& ev_init (&timer, callback); |
1746 | \& last_activity = ev_now (loop); |
2060 | \& callback (EV_A_ &timer, 0); |
1747 | \& callback (loop, timer, EV_TIMEOUT); |
|
|
1748 | .Ve |
2061 | .Ve |
1749 | .Sp |
2062 | .Sp |
1750 | And when there is some activity, simply store the current time in |
2063 | When there is some activity, simply store the current time in |
1751 | \&\f(CW\*(C`last_activity\*(C'\fR, no libev calls at all: |
2064 | \&\f(CW\*(C`last_activity\*(C'\fR, no libev calls at all: |
1752 | .Sp |
2065 | .Sp |
1753 | .Vb 1 |
2066 | .Vb 2 |
|
|
2067 | \& if (activity detected) |
1754 | \& last_actiivty = ev_now (loop); |
2068 | \& last_activity = ev_now (EV_A); |
|
|
2069 | .Ve |
|
|
2070 | .Sp |
|
|
2071 | When your timeout value changes, then the timeout can be changed by simply |
|
|
2072 | providing a new value, stopping the timer and calling the callback, which |
|
|
2073 | will again do the right thing (for example, time out immediately :). |
|
|
2074 | .Sp |
|
|
2075 | .Vb 3 |
|
|
2076 | \& timeout = new_value; |
|
|
2077 | \& ev_timer_stop (EV_A_ &timer); |
|
|
2078 | \& callback (EV_A_ &timer, 0); |
1755 | .Ve |
2079 | .Ve |
1756 | .Sp |
2080 | .Sp |
1757 | This technique is slightly more complex, but in most cases where the |
2081 | This technique is slightly more complex, but in most cases where the |
1758 | time-out is unlikely to be triggered, much more efficient. |
2082 | time-out is unlikely to be triggered, much more efficient. |
1759 | .Sp |
|
|
1760 | Changing the timeout is trivial as well (if it isn't hard-coded in the |
|
|
1761 | callback :) \- just change the timeout and invoke the callback, which will |
|
|
1762 | fix things for you. |
|
|
1763 | .IP "4. Wee, just use a double-linked list for your timeouts." 4 |
2083 | .IP "4. Wee, just use a double-linked list for your timeouts." 4 |
1764 | .IX Item "4. Wee, just use a double-linked list for your timeouts." |
2084 | .IX Item "4. Wee, just use a double-linked list for your timeouts." |
1765 | If there is not one request, but many thousands (millions...), all |
2085 | If there is not one request, but many thousands (millions...), all |
1766 | employing some kind of timeout with the same timeout value, then one can |
2086 | employing some kind of timeout with the same timeout value, then one can |
1767 | do even better: |
2087 | do even better: |
… | |
… | |
1791 | Method #1 is almost always a bad idea, and buys you nothing. Method #4 is |
2111 | Method #1 is almost always a bad idea, and buys you nothing. Method #4 is |
1792 | rather complicated, but extremely efficient, something that really pays |
2112 | rather complicated, but extremely efficient, something that really pays |
1793 | off after the first million or so of active timers, i.e. it's usually |
2113 | off after the first million or so of active timers, i.e. it's usually |
1794 | overkill :) |
2114 | overkill :) |
1795 | .PP |
2115 | .PP |
|
|
2116 | \fIThe special problem of being too early\fR |
|
|
2117 | .IX Subsection "The special problem of being too early" |
|
|
2118 | .PP |
|
|
2119 | If you ask a timer to call your callback after three seconds, then |
|
|
2120 | you expect it to be invoked after three seconds \- but of course, this |
|
|
2121 | cannot be guaranteed to infinite precision. Less obviously, it cannot be |
|
|
2122 | guaranteed to any precision by libev \- imagine somebody suspending the |
|
|
2123 | process with a \s-1STOP\s0 signal for a few hours for example. |
|
|
2124 | .PP |
|
|
2125 | So, libev tries to invoke your callback as soon as possible \fIafter\fR the |
|
|
2126 | delay has occurred, but cannot guarantee this. |
|
|
2127 | .PP |
|
|
2128 | A less obvious failure mode is calling your callback too early: many event |
|
|
2129 | loops compare timestamps with a \*(L"elapsed delay >= requested delay\*(R", but |
|
|
2130 | this can cause your callback to be invoked much earlier than you would |
|
|
2131 | expect. |
|
|
2132 | .PP |
|
|
2133 | To see why, imagine a system with a clock that only offers full second |
|
|
2134 | resolution (think windows if you can't come up with a broken enough \s-1OS\s0 |
|
|
2135 | yourself). If you schedule a one-second timer at the time 500.9, then the |
|
|
2136 | event loop will schedule your timeout to elapse at a system time of 500 |
|
|
2137 | (500.9 truncated to the resolution) + 1, or 501. |
|
|
2138 | .PP |
|
|
2139 | If an event library looks at the timeout 0.1s later, it will see \*(L"501 >= |
|
|
2140 | 501\*(R" and invoke the callback 0.1s after it was started, even though a |
|
|
2141 | one-second delay was requested \- this is being \*(L"too early\*(R", despite best |
|
|
2142 | intentions. |
|
|
2143 | .PP |
|
|
2144 | This is the reason why libev will never invoke the callback if the elapsed |
|
|
2145 | delay equals the requested delay, but only when the elapsed delay is |
|
|
2146 | larger than the requested delay. In the example above, libev would only invoke |
|
|
2147 | the callback at system time 502, or 1.1s after the timer was started. |
|
|
2148 | .PP |
|
|
2149 | So, while libev cannot guarantee that your callback will be invoked |
|
|
2150 | exactly when requested, it \fIcan\fR and \fIdoes\fR guarantee that the requested |
|
|
2151 | delay has actually elapsed, or in other words, it always errs on the \*(L"too |
|
|
2152 | late\*(R" side of things. |
|
|
2153 | .PP |
1796 | \fIThe special problem of time updates\fR |
2154 | \fIThe special problem of time updates\fR |
1797 | .IX Subsection "The special problem of time updates" |
2155 | .IX Subsection "The special problem of time updates" |
1798 | .PP |
2156 | .PP |
1799 | Establishing the current time is a costly operation (it usually takes at |
2157 | Establishing the current time is a costly operation (it usually takes |
1800 | least two system calls): \s-1EV\s0 therefore updates its idea of the current |
2158 | at least one system call): \s-1EV\s0 therefore updates its idea of the current |
1801 | time only before and after \f(CW\*(C`ev_loop\*(C'\fR collects new events, which causes a |
2159 | time only before and after \f(CW\*(C`ev_run\*(C'\fR collects new events, which causes a |
1802 | growing difference between \f(CW\*(C`ev_now ()\*(C'\fR and \f(CW\*(C`ev_time ()\*(C'\fR when handling |
2160 | growing difference between \f(CW\*(C`ev_now ()\*(C'\fR and \f(CW\*(C`ev_time ()\*(C'\fR when handling |
1803 | lots of events in one iteration. |
2161 | lots of events in one iteration. |
1804 | .PP |
2162 | .PP |
1805 | The relative timeouts are calculated relative to the \f(CW\*(C`ev_now ()\*(C'\fR |
2163 | The relative timeouts are calculated relative to the \f(CW\*(C`ev_now ()\*(C'\fR |
1806 | time. This is usually the right thing as this timestamp refers to the time |
2164 | time. This is usually the right thing as this timestamp refers to the time |
1807 | of the event triggering whatever timeout you are modifying/starting. If |
2165 | of the event triggering whatever timeout you are modifying/starting. If |
1808 | you suspect event processing to be delayed and you \fIneed\fR to base the |
2166 | you suspect event processing to be delayed and you \fIneed\fR to base the |
1809 | timeout on the current time, use something like this to adjust for this: |
2167 | timeout on the current time, use something like the following to adjust |
|
|
2168 | for it: |
1810 | .PP |
2169 | .PP |
1811 | .Vb 1 |
2170 | .Vb 1 |
1812 | \& ev_timer_set (&timer, after + ev_now () \- ev_time (), 0.); |
2171 | \& ev_timer_set (&timer, after + (ev_time () \- ev_now ()), 0.); |
1813 | .Ve |
2172 | .Ve |
1814 | .PP |
2173 | .PP |
1815 | If the event loop is suspended for a long time, you can also force an |
2174 | If the event loop is suspended for a long time, you can also force an |
1816 | update of the time returned by \f(CW\*(C`ev_now ()\*(C'\fR by calling \f(CW\*(C`ev_now_update |
2175 | update of the time returned by \f(CW\*(C`ev_now ()\*(C'\fR by calling \f(CW\*(C`ev_now_update |
1817 | ()\*(C'\fR. |
2176 | ()\*(C'\fR, although that will push the event time of all outstanding events |
|
|
2177 | further into the future. |
|
|
2178 | .PP |
|
|
2179 | \fIThe special problem of unsynchronised clocks\fR |
|
|
2180 | .IX Subsection "The special problem of unsynchronised clocks" |
|
|
2181 | .PP |
|
|
2182 | Modern systems have a variety of clocks \- libev itself uses the normal |
|
|
2183 | \&\*(L"wall clock\*(R" clock and, if available, the monotonic clock (to avoid time |
|
|
2184 | jumps). |
|
|
2185 | .PP |
|
|
2186 | Neither of these clocks is synchronised with each other or any other clock |
|
|
2187 | on the system, so \f(CW\*(C`ev_time ()\*(C'\fR might return a considerably different time |
|
|
2188 | than \f(CW\*(C`gettimeofday ()\*(C'\fR or \f(CW\*(C`time ()\*(C'\fR. On a GNU/Linux system, for example, |
|
|
2189 | a call to \f(CW\*(C`gettimeofday\*(C'\fR might return a second count that is one higher |
|
|
2190 | than a directly following call to \f(CW\*(C`time\*(C'\fR. |
|
|
2191 | .PP |
|
|
2192 | The moral of this is to only compare libev-related timestamps with |
|
|
2193 | \&\f(CW\*(C`ev_time ()\*(C'\fR and \f(CW\*(C`ev_now ()\*(C'\fR, at least if you want better precision than |
|
|
2194 | a second or so. |
|
|
2195 | .PP |
|
|
2196 | One more problem arises due to this lack of synchronisation: if libev uses |
|
|
2197 | the system monotonic clock and you compare timestamps from \f(CW\*(C`ev_time\*(C'\fR |
|
|
2198 | or \f(CW\*(C`ev_now\*(C'\fR from when you started your timer and when your callback is |
|
|
2199 | invoked, you will find that sometimes the callback is a bit \*(L"early\*(R". |
|
|
2200 | .PP |
|
|
2201 | This is because \f(CW\*(C`ev_timer\*(C'\fRs work in real time, not wall clock time, so |
|
|
2202 | libev makes sure your callback is not invoked before the delay happened, |
|
|
2203 | \&\fImeasured according to the real time\fR, not the system clock. |
|
|
2204 | .PP |
|
|
2205 | If your timeouts are based on a physical timescale (e.g. \*(L"time out this |
|
|
2206 | connection after 100 seconds\*(R") then this shouldn't bother you as it is |
|
|
2207 | exactly the right behaviour. |
|
|
2208 | .PP |
|
|
2209 | If you want to compare wall clock/system timestamps to your timers, then |
|
|
2210 | you need to use \f(CW\*(C`ev_periodic\*(C'\fRs, as these are based on the wall clock |
|
|
2211 | time, where your comparisons will always generate correct results. |
|
|
2212 | .PP |
|
|
2213 | \fIThe special problems of suspended animation\fR |
|
|
2214 | .IX Subsection "The special problems of suspended animation" |
|
|
2215 | .PP |
|
|
2216 | When you leave the server world it is quite customary to hit machines that |
|
|
2217 | can suspend/hibernate \- what happens to the clocks during such a suspend? |
|
|
2218 | .PP |
|
|
2219 | Some quick tests made with a Linux 2.6.28 indicate that a suspend freezes |
|
|
2220 | all processes, while the clocks (\f(CW\*(C`times\*(C'\fR, \f(CW\*(C`CLOCK_MONOTONIC\*(C'\fR) continue |
|
|
2221 | to run until the system is suspended, but they will not advance while the |
|
|
2222 | system is suspended. That means, on resume, it will be as if the program |
|
|
2223 | was frozen for a few seconds, but the suspend time will not be counted |
|
|
2224 | towards \f(CW\*(C`ev_timer\*(C'\fR when a monotonic clock source is used. The real time |
|
|
2225 | clock advanced as expected, but if it is used as sole clocksource, then a |
|
|
2226 | long suspend would be detected as a time jump by libev, and timers would |
|
|
2227 | be adjusted accordingly. |
|
|
2228 | .PP |
|
|
2229 | I would not be surprised to see different behaviour in different between |
|
|
2230 | operating systems, \s-1OS\s0 versions or even different hardware. |
|
|
2231 | .PP |
|
|
2232 | The other form of suspend (job control, or sending a \s-1SIGSTOP\s0) will see a |
|
|
2233 | time jump in the monotonic clocks and the realtime clock. If the program |
|
|
2234 | is suspended for a very long time, and monotonic clock sources are in use, |
|
|
2235 | then you can expect \f(CW\*(C`ev_timer\*(C'\fRs to expire as the full suspension time |
|
|
2236 | will be counted towards the timers. When no monotonic clock source is in |
|
|
2237 | use, then libev will again assume a timejump and adjust accordingly. |
|
|
2238 | .PP |
|
|
2239 | It might be beneficial for this latter case to call \f(CW\*(C`ev_suspend\*(C'\fR |
|
|
2240 | and \f(CW\*(C`ev_resume\*(C'\fR in code that handles \f(CW\*(C`SIGTSTP\*(C'\fR, to at least get |
|
|
2241 | deterministic behaviour in this case (you can do nothing against |
|
|
2242 | \&\f(CW\*(C`SIGSTOP\*(C'\fR). |
1818 | .PP |
2243 | .PP |
1819 | \fIWatcher-Specific Functions and Data Members\fR |
2244 | \fIWatcher-Specific Functions and Data Members\fR |
1820 | .IX Subsection "Watcher-Specific Functions and Data Members" |
2245 | .IX Subsection "Watcher-Specific Functions and Data Members" |
1821 | .IP "ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)" 4 |
2246 | .IP "ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)" 4 |
1822 | .IX Item "ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)" |
2247 | .IX Item "ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)" |
… | |
… | |
1835 | trigger at exactly 10 second intervals. If, however, your program cannot |
2260 | trigger at exactly 10 second intervals. If, however, your program cannot |
1836 | keep up with the timer (because it takes longer than those 10 seconds to |
2261 | keep up with the timer (because it takes longer than those 10 seconds to |
1837 | do stuff) the timer will not fire more than once per event loop iteration. |
2262 | do stuff) the timer will not fire more than once per event loop iteration. |
1838 | .IP "ev_timer_again (loop, ev_timer *)" 4 |
2263 | .IP "ev_timer_again (loop, ev_timer *)" 4 |
1839 | .IX Item "ev_timer_again (loop, ev_timer *)" |
2264 | .IX Item "ev_timer_again (loop, ev_timer *)" |
1840 | This will act as if the timer timed out and restart it again if it is |
2265 | This will act as if the timer timed out, and restarts it again if it is |
1841 | repeating. The exact semantics are: |
2266 | repeating. It basically works like calling \f(CW\*(C`ev_timer_stop\*(C'\fR, updating the |
|
|
2267 | timeout to the \f(CW\*(C`repeat\*(C'\fR value and calling \f(CW\*(C`ev_timer_start\*(C'\fR. |
1842 | .Sp |
2268 | .Sp |
|
|
2269 | The exact semantics are as in the following rules, all of which will be |
|
|
2270 | applied to the watcher: |
|
|
2271 | .RS 4 |
1843 | If the timer is pending, its pending status is cleared. |
2272 | .IP "If the timer is pending, the pending status is always cleared." 4 |
1844 | .Sp |
2273 | .IX Item "If the timer is pending, the pending status is always cleared." |
|
|
2274 | .PD 0 |
1845 | If the timer is started but non-repeating, stop it (as if it timed out). |
2275 | .IP "If the timer is started but non-repeating, stop it (as if it timed out, without invoking it)." 4 |
1846 | .Sp |
2276 | .IX Item "If the timer is started but non-repeating, stop it (as if it timed out, without invoking it)." |
1847 | If the timer is repeating, either start it if necessary (with the |
2277 | .ie n .IP "If the timer is repeating, make the ""repeat"" value the new timeout and start the timer, if necessary." 4 |
1848 | \&\f(CW\*(C`repeat\*(C'\fR value), or reset the running timer to the \f(CW\*(C`repeat\*(C'\fR value. |
2278 | .el .IP "If the timer is repeating, make the \f(CWrepeat\fR value the new timeout and start the timer, if necessary." 4 |
|
|
2279 | .IX Item "If the timer is repeating, make the repeat value the new timeout and start the timer, if necessary." |
|
|
2280 | .RE |
|
|
2281 | .RS 4 |
|
|
2282 | .PD |
1849 | .Sp |
2283 | .Sp |
1850 | This sounds a bit complicated, see \*(L"Be smart about timeouts\*(R", above, for a |
2284 | This sounds a bit complicated, see \*(L"Be smart about timeouts\*(R", above, for a |
1851 | usage example. |
2285 | usage example. |
|
|
2286 | .RE |
|
|
2287 | .IP "ev_tstamp ev_timer_remaining (loop, ev_timer *)" 4 |
|
|
2288 | .IX Item "ev_tstamp ev_timer_remaining (loop, ev_timer *)" |
|
|
2289 | Returns the remaining time until a timer fires. If the timer is active, |
|
|
2290 | then this time is relative to the current event loop time, otherwise it's |
|
|
2291 | the timeout value currently configured. |
|
|
2292 | .Sp |
|
|
2293 | That is, after an \f(CW\*(C`ev_timer_set (w, 5, 7)\*(C'\fR, \f(CW\*(C`ev_timer_remaining\*(C'\fR returns |
|
|
2294 | \&\f(CW5\fR. When the timer is started and one second passes, \f(CW\*(C`ev_timer_remaining\*(C'\fR |
|
|
2295 | will return \f(CW4\fR. When the timer expires and is restarted, it will return |
|
|
2296 | roughly \f(CW7\fR (likely slightly less as callback invocation takes some time, |
|
|
2297 | too), and so on. |
1852 | .IP "ev_tstamp repeat [read\-write]" 4 |
2298 | .IP "ev_tstamp repeat [read\-write]" 4 |
1853 | .IX Item "ev_tstamp repeat [read-write]" |
2299 | .IX Item "ev_tstamp repeat [read-write]" |
1854 | The current \f(CW\*(C`repeat\*(C'\fR value. Will be used each time the watcher times out |
2300 | The current \f(CW\*(C`repeat\*(C'\fR value. Will be used each time the watcher times out |
1855 | or \f(CW\*(C`ev_timer_again\*(C'\fR is called, and determines the next timeout (if any), |
2301 | or \f(CW\*(C`ev_timer_again\*(C'\fR is called, and determines the next timeout (if any), |
1856 | which is also when any modifications are taken into account. |
2302 | which is also when any modifications are taken into account. |
… | |
… | |
1883 | \& } |
2329 | \& } |
1884 | \& |
2330 | \& |
1885 | \& ev_timer mytimer; |
2331 | \& ev_timer mytimer; |
1886 | \& ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */ |
2332 | \& ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */ |
1887 | \& ev_timer_again (&mytimer); /* start timer */ |
2333 | \& ev_timer_again (&mytimer); /* start timer */ |
1888 | \& ev_loop (loop, 0); |
2334 | \& ev_run (loop, 0); |
1889 | \& |
2335 | \& |
1890 | \& // and in some piece of code that gets executed on any "activity": |
2336 | \& // and in some piece of code that gets executed on any "activity": |
1891 | \& // reset the timeout to start ticking again at 10 seconds |
2337 | \& // reset the timeout to start ticking again at 10 seconds |
1892 | \& ev_timer_again (&mytimer); |
2338 | \& ev_timer_again (&mytimer); |
1893 | .Ve |
2339 | .Ve |
1894 | .ie n .Sh """ev_periodic"" \- to cron or not to cron?" |
2340 | .ie n .SS """ev_periodic"" \- to cron or not to cron?" |
1895 | .el .Sh "\f(CWev_periodic\fP \- to cron or not to cron?" |
2341 | .el .SS "\f(CWev_periodic\fP \- to cron or not to cron?" |
1896 | .IX Subsection "ev_periodic - to cron or not to cron?" |
2342 | .IX Subsection "ev_periodic - to cron or not to cron?" |
1897 | Periodic watchers are also timers of a kind, but they are very versatile |
2343 | Periodic watchers are also timers of a kind, but they are very versatile |
1898 | (and unfortunately a bit complex). |
2344 | (and unfortunately a bit complex). |
1899 | .PP |
2345 | .PP |
1900 | Unlike \f(CW\*(C`ev_timer\*(C'\fR, periodic watchers are not based on real time (or |
2346 | Unlike \f(CW\*(C`ev_timer\*(C'\fR, periodic watchers are not based on real time (or |
… | |
… | |
1919 | .PP |
2365 | .PP |
1920 | As with timers, the callback is guaranteed to be invoked only when the |
2366 | As with timers, the callback is guaranteed to be invoked only when the |
1921 | point in time where it is supposed to trigger has passed. If multiple |
2367 | point in time where it is supposed to trigger has passed. If multiple |
1922 | timers become ready during the same loop iteration then the ones with |
2368 | timers become ready during the same loop iteration then the ones with |
1923 | earlier time-out values are invoked before ones with later time-out values |
2369 | earlier time-out values are invoked before ones with later time-out values |
1924 | (but this is no longer true when a callback calls \f(CW\*(C`ev_loop\*(C'\fR recursively). |
2370 | (but this is no longer true when a callback calls \f(CW\*(C`ev_run\*(C'\fR recursively). |
1925 | .PP |
2371 | .PP |
1926 | \fIWatcher-Specific Functions and Data Members\fR |
2372 | \fIWatcher-Specific Functions and Data Members\fR |
1927 | .IX Subsection "Watcher-Specific Functions and Data Members" |
2373 | .IX Subsection "Watcher-Specific Functions and Data Members" |
1928 | .IP "ev_periodic_init (ev_periodic *, callback, ev_tstamp offset, ev_tstamp interval, reschedule_cb)" 4 |
2374 | .IP "ev_periodic_init (ev_periodic *, callback, ev_tstamp offset, ev_tstamp interval, reschedule_cb)" 4 |
1929 | .IX Item "ev_periodic_init (ev_periodic *, callback, ev_tstamp offset, ev_tstamp interval, reschedule_cb)" |
2375 | .IX Item "ev_periodic_init (ev_periodic *, callback, ev_tstamp offset, ev_tstamp interval, reschedule_cb)" |
… | |
… | |
1965 | .Sp |
2411 | .Sp |
1966 | Another way to think about it (for the mathematically inclined) is that |
2412 | Another way to think about it (for the mathematically inclined) is that |
1967 | \&\f(CW\*(C`ev_periodic\*(C'\fR will try to run the callback in this mode at the next possible |
2413 | \&\f(CW\*(C`ev_periodic\*(C'\fR will try to run the callback in this mode at the next possible |
1968 | time where \f(CW\*(C`time = offset (mod interval)\*(C'\fR, regardless of any time jumps. |
2414 | time where \f(CW\*(C`time = offset (mod interval)\*(C'\fR, regardless of any time jumps. |
1969 | .Sp |
2415 | .Sp |
1970 | For numerical stability it is preferable that the \f(CW\*(C`offset\*(C'\fR value is near |
2416 | The \f(CW\*(C`interval\*(C'\fR \fI\s-1MUST\s0\fR be positive, and for numerical stability, the |
1971 | \&\f(CW\*(C`ev_now ()\*(C'\fR (the current time), but there is no range requirement for |
2417 | interval value should be higher than \f(CW\*(C`1/8192\*(C'\fR (which is around 100 |
1972 | this value, and in fact is often specified as zero. |
2418 | microseconds) and \f(CW\*(C`offset\*(C'\fR should be higher than \f(CW0\fR and should have |
|
|
2419 | at most a similar magnitude as the current time (say, within a factor of |
|
|
2420 | ten). Typical values for offset are, in fact, \f(CW0\fR or something between |
|
|
2421 | \&\f(CW0\fR and \f(CW\*(C`interval\*(C'\fR, which is also the recommended range. |
1973 | .Sp |
2422 | .Sp |
1974 | Note also that there is an upper limit to how often a timer can fire (\s-1CPU\s0 |
2423 | Note also that there is an upper limit to how often a timer can fire (\s-1CPU\s0 |
1975 | speed for example), so if \f(CW\*(C`interval\*(C'\fR is very small then timing stability |
2424 | speed for example), so if \f(CW\*(C`interval\*(C'\fR is very small then timing stability |
1976 | will of course deteriorate. Libev itself tries to be exact to be about one |
2425 | will of course deteriorate. Libev itself tries to be exact to be about one |
1977 | millisecond (if the \s-1OS\s0 supports it and the machine is fast enough). |
2426 | millisecond (if the \s-1OS\s0 supports it and the machine is fast enough). |
… | |
… | |
1981 | In this mode the values for \f(CW\*(C`interval\*(C'\fR and \f(CW\*(C`offset\*(C'\fR are both being |
2430 | In this mode the values for \f(CW\*(C`interval\*(C'\fR and \f(CW\*(C`offset\*(C'\fR are both being |
1982 | ignored. Instead, each time the periodic watcher gets scheduled, the |
2431 | ignored. Instead, each time the periodic watcher gets scheduled, the |
1983 | reschedule callback will be called with the watcher as first, and the |
2432 | reschedule callback will be called with the watcher as first, and the |
1984 | current time as second argument. |
2433 | current time as second argument. |
1985 | .Sp |
2434 | .Sp |
1986 | \&\s-1NOTE:\s0 \fIThis callback \s-1MUST\s0 \s-1NOT\s0 stop or destroy any periodic watcher, ever, |
2435 | \&\s-1NOTE: \s0\fIThis callback \s-1MUST NOT\s0 stop or destroy any periodic watcher, ever, |
1987 | or make \s-1ANY\s0 other event loop modifications whatsoever, unless explicitly |
2436 | or make \s-1ANY\s0 other event loop modifications whatsoever, unless explicitly |
1988 | allowed by documentation here\fR. |
2437 | allowed by documentation here\fR. |
1989 | .Sp |
2438 | .Sp |
1990 | If you need to stop it, return \f(CW\*(C`now + 1e30\*(C'\fR (or so, fudge fudge) and stop |
2439 | If you need to stop it, return \f(CW\*(C`now + 1e30\*(C'\fR (or so, fudge fudge) and stop |
1991 | it afterwards (e.g. by starting an \f(CW\*(C`ev_prepare\*(C'\fR watcher, which is the |
2440 | it afterwards (e.g. by starting an \f(CW\*(C`ev_prepare\*(C'\fR watcher, which is the |
… | |
… | |
2005 | It must return the next time to trigger, based on the passed time value |
2454 | It must return the next time to trigger, based on the passed time value |
2006 | (that is, the lowest time value larger than to the second argument). It |
2455 | (that is, the lowest time value larger than to the second argument). It |
2007 | will usually be called just before the callback will be triggered, but |
2456 | will usually be called just before the callback will be triggered, but |
2008 | might be called at other times, too. |
2457 | might be called at other times, too. |
2009 | .Sp |
2458 | .Sp |
2010 | \&\s-1NOTE:\s0 \fIThis callback must always return a time that is higher than or |
2459 | \&\s-1NOTE: \s0\fIThis callback must always return a time that is higher than or |
2011 | equal to the passed \f(CI\*(C`now\*(C'\fI value\fR. |
2460 | equal to the passed \f(CI\*(C`now\*(C'\fI value\fR. |
2012 | .Sp |
2461 | .Sp |
2013 | This can be used to create very complex timers, such as a timer that |
2462 | This can be used to create very complex timers, such as a timer that |
2014 | triggers on \*(L"next midnight, local time\*(R". To do this, you would calculate the |
2463 | triggers on \*(L"next midnight, local time\*(R". To do this, you would calculate the |
2015 | next midnight after \f(CW\*(C`now\*(C'\fR and return the timestamp value for this. How |
2464 | next midnight after \f(CW\*(C`now\*(C'\fR and return the timestamp value for this. How |
… | |
… | |
2056 | system time is divisible by 3600. The callback invocation times have |
2505 | system time is divisible by 3600. The callback invocation times have |
2057 | potentially a lot of jitter, but good long-term stability. |
2506 | potentially a lot of jitter, but good long-term stability. |
2058 | .PP |
2507 | .PP |
2059 | .Vb 5 |
2508 | .Vb 5 |
2060 | \& static void |
2509 | \& static void |
2061 | \& clock_cb (struct ev_loop *loop, ev_io *w, int revents) |
2510 | \& clock_cb (struct ev_loop *loop, ev_periodic *w, int revents) |
2062 | \& { |
2511 | \& { |
2063 | \& ... its now a full hour (UTC, or TAI or whatever your clock follows) |
2512 | \& ... its now a full hour (UTC, or TAI or whatever your clock follows) |
2064 | \& } |
2513 | \& } |
2065 | \& |
2514 | \& |
2066 | \& ev_periodic hourly_tick; |
2515 | \& ev_periodic hourly_tick; |
… | |
… | |
2088 | \& ev_periodic hourly_tick; |
2537 | \& ev_periodic hourly_tick; |
2089 | \& ev_periodic_init (&hourly_tick, clock_cb, |
2538 | \& ev_periodic_init (&hourly_tick, clock_cb, |
2090 | \& fmod (ev_now (loop), 3600.), 3600., 0); |
2539 | \& fmod (ev_now (loop), 3600.), 3600., 0); |
2091 | \& ev_periodic_start (loop, &hourly_tick); |
2540 | \& ev_periodic_start (loop, &hourly_tick); |
2092 | .Ve |
2541 | .Ve |
2093 | .ie n .Sh """ev_signal"" \- signal me when a signal gets signalled!" |
2542 | .ie n .SS """ev_signal"" \- signal me when a signal gets signalled!" |
2094 | .el .Sh "\f(CWev_signal\fP \- signal me when a signal gets signalled!" |
2543 | .el .SS "\f(CWev_signal\fP \- signal me when a signal gets signalled!" |
2095 | .IX Subsection "ev_signal - signal me when a signal gets signalled!" |
2544 | .IX Subsection "ev_signal - signal me when a signal gets signalled!" |
2096 | Signal watchers will trigger an event when the process receives a specific |
2545 | Signal watchers will trigger an event when the process receives a specific |
2097 | signal one or more times. Even though signals are very asynchronous, libev |
2546 | signal one or more times. Even though signals are very asynchronous, libev |
2098 | will try it's best to deliver signals synchronously, i.e. as part of the |
2547 | will try its best to deliver signals synchronously, i.e. as part of the |
2099 | normal event processing, like any other event. |
2548 | normal event processing, like any other event. |
2100 | .PP |
2549 | .PP |
2101 | If you want signals asynchronously, just use \f(CW\*(C`sigaction\*(C'\fR as you would |
2550 | If you want signals to be delivered truly asynchronously, just use |
2102 | do without libev and forget about sharing the signal. You can even use |
2551 | \&\f(CW\*(C`sigaction\*(C'\fR as you would do without libev and forget about sharing |
2103 | \&\f(CW\*(C`ev_async\*(C'\fR from a signal handler to synchronously wake up an event loop. |
2552 | the signal. You can even use \f(CW\*(C`ev_async\*(C'\fR from a signal handler to |
|
|
2553 | synchronously wake up an event loop. |
2104 | .PP |
2554 | .PP |
2105 | You can configure as many watchers as you like per signal. Only when the |
2555 | You can configure as many watchers as you like for the same signal, but |
2106 | first watcher gets started will libev actually register a signal handler |
2556 | only within the same loop, i.e. you can watch for \f(CW\*(C`SIGINT\*(C'\fR in your |
2107 | with the kernel (thus it coexists with your own signal handlers as long as |
2557 | default loop and for \f(CW\*(C`SIGIO\*(C'\fR in another loop, but you cannot watch for |
2108 | you don't register any with libev for the same signal). Similarly, when |
2558 | \&\f(CW\*(C`SIGINT\*(C'\fR in both the default loop and another loop at the same time. At |
2109 | the last signal watcher for a signal is stopped, libev will reset the |
2559 | the moment, \f(CW\*(C`SIGCHLD\*(C'\fR is permanently tied to the default loop. |
2110 | signal handler to \s-1SIG_DFL\s0 (regardless of what it was set to before). |
2560 | .PP |
|
|
2561 | Only after the first watcher for a signal is started will libev actually |
|
|
2562 | register something with the kernel. It thus coexists with your own signal |
|
|
2563 | handlers as long as you don't register any with libev for the same signal. |
2111 | .PP |
2564 | .PP |
2112 | If possible and supported, libev will install its handlers with |
2565 | If possible and supported, libev will install its handlers with |
2113 | \&\f(CW\*(C`SA_RESTART\*(C'\fR behaviour enabled, so system calls should not be unduly |
2566 | \&\f(CW\*(C`SA_RESTART\*(C'\fR (or equivalent) behaviour enabled, so system calls should |
2114 | interrupted. If you have a problem with system calls getting interrupted by |
2567 | not be unduly interrupted. If you have a problem with system calls getting |
2115 | signals you can block all signals in an \f(CW\*(C`ev_check\*(C'\fR watcher and unblock |
2568 | interrupted by signals you can block all signals in an \f(CW\*(C`ev_check\*(C'\fR watcher |
2116 | them in an \f(CW\*(C`ev_prepare\*(C'\fR watcher. |
2569 | and unblock them in an \f(CW\*(C`ev_prepare\*(C'\fR watcher. |
|
|
2570 | .PP |
|
|
2571 | \fIThe special problem of inheritance over fork/execve/pthread_create\fR |
|
|
2572 | .IX Subsection "The special problem of inheritance over fork/execve/pthread_create" |
|
|
2573 | .PP |
|
|
2574 | Both the signal mask (\f(CW\*(C`sigprocmask\*(C'\fR) and the signal disposition |
|
|
2575 | (\f(CW\*(C`sigaction\*(C'\fR) are unspecified after starting a signal watcher (and after |
|
|
2576 | stopping it again), that is, libev might or might not block the signal, |
|
|
2577 | and might or might not set or restore the installed signal handler (but |
|
|
2578 | see \f(CW\*(C`EVFLAG_NOSIGMASK\*(C'\fR). |
|
|
2579 | .PP |
|
|
2580 | While this does not matter for the signal disposition (libev never |
|
|
2581 | sets signals to \f(CW\*(C`SIG_IGN\*(C'\fR, so handlers will be reset to \f(CW\*(C`SIG_DFL\*(C'\fR on |
|
|
2582 | \&\f(CW\*(C`execve\*(C'\fR), this matters for the signal mask: many programs do not expect |
|
|
2583 | certain signals to be blocked. |
|
|
2584 | .PP |
|
|
2585 | This means that before calling \f(CW\*(C`exec\*(C'\fR (from the child) you should reset |
|
|
2586 | the signal mask to whatever \*(L"default\*(R" you expect (all clear is a good |
|
|
2587 | choice usually). |
|
|
2588 | .PP |
|
|
2589 | The simplest way to ensure that the signal mask is reset in the child is |
|
|
2590 | to install a fork handler with \f(CW\*(C`pthread_atfork\*(C'\fR that resets it. That will |
|
|
2591 | catch fork calls done by libraries (such as the libc) as well. |
|
|
2592 | .PP |
|
|
2593 | In current versions of libev, the signal will not be blocked indefinitely |
|
|
2594 | unless you use the \f(CW\*(C`signalfd\*(C'\fR \s-1API \s0(\f(CW\*(C`EV_SIGNALFD\*(C'\fR). While this reduces |
|
|
2595 | the window of opportunity for problems, it will not go away, as libev |
|
|
2596 | \&\fIhas\fR to modify the signal mask, at least temporarily. |
|
|
2597 | .PP |
|
|
2598 | So I can't stress this enough: \fIIf you do not reset your signal mask when |
|
|
2599 | you expect it to be empty, you have a race condition in your code\fR. This |
|
|
2600 | is not a libev-specific thing, this is true for most event libraries. |
|
|
2601 | .PP |
|
|
2602 | \fIThe special problem of threads signal handling\fR |
|
|
2603 | .IX Subsection "The special problem of threads signal handling" |
|
|
2604 | .PP |
|
|
2605 | \&\s-1POSIX\s0 threads has problematic signal handling semantics, specifically, |
|
|
2606 | a lot of functionality (sigfd, sigwait etc.) only really works if all |
|
|
2607 | threads in a process block signals, which is hard to achieve. |
|
|
2608 | .PP |
|
|
2609 | When you want to use sigwait (or mix libev signal handling with your own |
|
|
2610 | for the same signals), you can tackle this problem by globally blocking |
|
|
2611 | all signals before creating any threads (or creating them with a fully set |
|
|
2612 | sigprocmask) and also specifying the \f(CW\*(C`EVFLAG_NOSIGMASK\*(C'\fR when creating |
|
|
2613 | loops. Then designate one thread as \*(L"signal receiver thread\*(R" which handles |
|
|
2614 | these signals. You can pass on any signals that libev might be interested |
|
|
2615 | in by calling \f(CW\*(C`ev_feed_signal\*(C'\fR. |
2117 | .PP |
2616 | .PP |
2118 | \fIWatcher-Specific Functions and Data Members\fR |
2617 | \fIWatcher-Specific Functions and Data Members\fR |
2119 | .IX Subsection "Watcher-Specific Functions and Data Members" |
2618 | .IX Subsection "Watcher-Specific Functions and Data Members" |
2120 | .IP "ev_signal_init (ev_signal *, callback, int signum)" 4 |
2619 | .IP "ev_signal_init (ev_signal *, callback, int signum)" 4 |
2121 | .IX Item "ev_signal_init (ev_signal *, callback, int signum)" |
2620 | .IX Item "ev_signal_init (ev_signal *, callback, int signum)" |
… | |
… | |
2130 | The signal the watcher watches out for. |
2629 | The signal the watcher watches out for. |
2131 | .PP |
2630 | .PP |
2132 | \fIExamples\fR |
2631 | \fIExamples\fR |
2133 | .IX Subsection "Examples" |
2632 | .IX Subsection "Examples" |
2134 | .PP |
2633 | .PP |
2135 | Example: Try to exit cleanly on \s-1SIGINT\s0. |
2634 | Example: Try to exit cleanly on \s-1SIGINT.\s0 |
2136 | .PP |
2635 | .PP |
2137 | .Vb 5 |
2636 | .Vb 5 |
2138 | \& static void |
2637 | \& static void |
2139 | \& sigint_cb (struct ev_loop *loop, ev_signal *w, int revents) |
2638 | \& sigint_cb (struct ev_loop *loop, ev_signal *w, int revents) |
2140 | \& { |
2639 | \& { |
2141 | \& ev_unloop (loop, EVUNLOOP_ALL); |
2640 | \& ev_break (loop, EVBREAK_ALL); |
2142 | \& } |
2641 | \& } |
2143 | \& |
2642 | \& |
2144 | \& ev_signal signal_watcher; |
2643 | \& ev_signal signal_watcher; |
2145 | \& ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
2644 | \& ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
2146 | \& ev_signal_start (loop, &signal_watcher); |
2645 | \& ev_signal_start (loop, &signal_watcher); |
2147 | .Ve |
2646 | .Ve |
2148 | .ie n .Sh """ev_child"" \- watch out for process status changes" |
2647 | .ie n .SS """ev_child"" \- watch out for process status changes" |
2149 | .el .Sh "\f(CWev_child\fP \- watch out for process status changes" |
2648 | .el .SS "\f(CWev_child\fP \- watch out for process status changes" |
2150 | .IX Subsection "ev_child - watch out for process status changes" |
2649 | .IX Subsection "ev_child - watch out for process status changes" |
2151 | Child watchers trigger when your process receives a \s-1SIGCHLD\s0 in response to |
2650 | Child watchers trigger when your process receives a \s-1SIGCHLD\s0 in response to |
2152 | some child status changes (most typically when a child of yours dies or |
2651 | some child status changes (most typically when a child of yours dies or |
2153 | exits). It is permissible to install a child watcher \fIafter\fR the child |
2652 | exits). It is permissible to install a child watcher \fIafter\fR the child |
2154 | has been forked (which implies it might have already exited), as long |
2653 | has been forked (which implies it might have already exited), as long |
2155 | as the event loop isn't entered (or is continued from a watcher), i.e., |
2654 | as the event loop isn't entered (or is continued from a watcher), i.e., |
2156 | forking and then immediately registering a watcher for the child is fine, |
2655 | forking and then immediately registering a watcher for the child is fine, |
2157 | but forking and registering a watcher a few event loop iterations later is |
2656 | but forking and registering a watcher a few event loop iterations later or |
2158 | not. |
2657 | in the next callback invocation is not. |
2159 | .PP |
2658 | .PP |
2160 | Only the default event loop is capable of handling signals, and therefore |
2659 | Only the default event loop is capable of handling signals, and therefore |
2161 | you can only register child watchers in the default event loop. |
2660 | you can only register child watchers in the default event loop. |
2162 | .PP |
2661 | .PP |
|
|
2662 | Due to some design glitches inside libev, child watchers will always be |
|
|
2663 | handled at maximum priority (their priority is set to \f(CW\*(C`EV_MAXPRI\*(C'\fR by |
|
|
2664 | libev) |
|
|
2665 | .PP |
2163 | \fIProcess Interaction\fR |
2666 | \fIProcess Interaction\fR |
2164 | .IX Subsection "Process Interaction" |
2667 | .IX Subsection "Process Interaction" |
2165 | .PP |
2668 | .PP |
2166 | Libev grabs \f(CW\*(C`SIGCHLD\*(C'\fR as soon as the default event loop is |
2669 | Libev grabs \f(CW\*(C`SIGCHLD\*(C'\fR as soon as the default event loop is |
2167 | initialised. This is necessary to guarantee proper behaviour even if |
2670 | initialised. This is necessary to guarantee proper behaviour even if the |
2168 | the first child watcher is started after the child exits. The occurrence |
2671 | first child watcher is started after the child exits. The occurrence |
2169 | of \f(CW\*(C`SIGCHLD\*(C'\fR is recorded asynchronously, but child reaping is done |
2672 | of \f(CW\*(C`SIGCHLD\*(C'\fR is recorded asynchronously, but child reaping is done |
2170 | synchronously as part of the event loop processing. Libev always reaps all |
2673 | synchronously as part of the event loop processing. Libev always reaps all |
2171 | children, even ones not watched. |
2674 | children, even ones not watched. |
2172 | .PP |
2675 | .PP |
2173 | \fIOverriding the Built-In Processing\fR |
2676 | \fIOverriding the Built-In Processing\fR |
… | |
… | |
2185 | .IX Subsection "Stopping the Child Watcher" |
2688 | .IX Subsection "Stopping the Child Watcher" |
2186 | .PP |
2689 | .PP |
2187 | Currently, the child watcher never gets stopped, even when the |
2690 | Currently, the child watcher never gets stopped, even when the |
2188 | child terminates, so normally one needs to stop the watcher in the |
2691 | child terminates, so normally one needs to stop the watcher in the |
2189 | callback. Future versions of libev might stop the watcher automatically |
2692 | callback. Future versions of libev might stop the watcher automatically |
2190 | when a child exit is detected. |
2693 | when a child exit is detected (calling \f(CW\*(C`ev_child_stop\*(C'\fR twice is not a |
|
|
2694 | problem). |
2191 | .PP |
2695 | .PP |
2192 | \fIWatcher-Specific Functions and Data Members\fR |
2696 | \fIWatcher-Specific Functions and Data Members\fR |
2193 | .IX Subsection "Watcher-Specific Functions and Data Members" |
2697 | .IX Subsection "Watcher-Specific Functions and Data Members" |
2194 | .IP "ev_child_init (ev_child *, callback, int pid, int trace)" 4 |
2698 | .IP "ev_child_init (ev_child *, callback, int pid, int trace)" 4 |
2195 | .IX Item "ev_child_init (ev_child *, callback, int pid, int trace)" |
2699 | .IX Item "ev_child_init (ev_child *, callback, int pid, int trace)" |
… | |
… | |
2245 | \& { |
2749 | \& { |
2246 | \& ev_child_init (&cw, child_cb, pid, 0); |
2750 | \& ev_child_init (&cw, child_cb, pid, 0); |
2247 | \& ev_child_start (EV_DEFAULT_ &cw); |
2751 | \& ev_child_start (EV_DEFAULT_ &cw); |
2248 | \& } |
2752 | \& } |
2249 | .Ve |
2753 | .Ve |
2250 | .ie n .Sh """ev_stat"" \- did the file attributes just change?" |
2754 | .ie n .SS """ev_stat"" \- did the file attributes just change?" |
2251 | .el .Sh "\f(CWev_stat\fP \- did the file attributes just change?" |
2755 | .el .SS "\f(CWev_stat\fP \- did the file attributes just change?" |
2252 | .IX Subsection "ev_stat - did the file attributes just change?" |
2756 | .IX Subsection "ev_stat - did the file attributes just change?" |
2253 | This watches a file system path for attribute changes. That is, it calls |
2757 | This watches a file system path for attribute changes. That is, it calls |
2254 | \&\f(CW\*(C`stat\*(C'\fR on that path in regular intervals (or when the \s-1OS\s0 says it changed) |
2758 | \&\f(CW\*(C`stat\*(C'\fR on that path in regular intervals (or when the \s-1OS\s0 says it changed) |
2255 | and sees if it changed compared to the last time, invoking the callback if |
2759 | and sees if it changed compared to the last time, invoking the callback |
2256 | it did. |
2760 | if it did. Starting the watcher \f(CW\*(C`stat\*(C'\fR's the file, so only changes that |
|
|
2761 | happen after the watcher has been started will be reported. |
2257 | .PP |
2762 | .PP |
2258 | The path does not need to exist: changing from \*(L"path exists\*(R" to \*(L"path does |
2763 | The path does not need to exist: changing from \*(L"path exists\*(R" to \*(L"path does |
2259 | not exist\*(R" is a status change like any other. The condition \*(L"path does not |
2764 | not exist\*(R" is a status change like any other. The condition \*(L"path does not |
2260 | exist\*(R" (or more correctly \*(L"path cannot be stat'ed\*(R") is signified by the |
2765 | exist\*(R" (or more correctly \*(L"path cannot be stat'ed\*(R") is signified by the |
2261 | \&\f(CW\*(C`st_nlink\*(C'\fR field being zero (which is otherwise always forced to be at |
2766 | \&\f(CW\*(C`st_nlink\*(C'\fR field being zero (which is otherwise always forced to be at |
… | |
… | |
2291 | compilation environment, which means that on systems with large file |
2796 | compilation environment, which means that on systems with large file |
2292 | support disabled by default, you get the 32 bit version of the stat |
2797 | support disabled by default, you get the 32 bit version of the stat |
2293 | structure. When using the library from programs that change the \s-1ABI\s0 to |
2798 | structure. When using the library from programs that change the \s-1ABI\s0 to |
2294 | use 64 bit file offsets the programs will fail. In that case you have to |
2799 | use 64 bit file offsets the programs will fail. In that case you have to |
2295 | compile libev with the same flags to get binary compatibility. This is |
2800 | compile libev with the same flags to get binary compatibility. This is |
2296 | obviously the case with any flags that change the \s-1ABI\s0, but the problem is |
2801 | obviously the case with any flags that change the \s-1ABI,\s0 but the problem is |
2297 | most noticeably displayed with ev_stat and large file support. |
2802 | most noticeably displayed with ev_stat and large file support. |
2298 | .PP |
2803 | .PP |
2299 | The solution for this is to lobby your distribution maker to make large |
2804 | The solution for this is to lobby your distribution maker to make large |
2300 | file interfaces available by default (as e.g. FreeBSD does) and not |
2805 | file interfaces available by default (as e.g. FreeBSD does) and not |
2301 | optional. Libev cannot simply switch on large file support because it has |
2806 | optional. Libev cannot simply switch on large file support because it has |
… | |
… | |
2470 | \& ... |
2975 | \& ... |
2471 | \& ev_stat_init (&passwd, stat_cb, "/etc/passwd", 0.); |
2976 | \& ev_stat_init (&passwd, stat_cb, "/etc/passwd", 0.); |
2472 | \& ev_stat_start (loop, &passwd); |
2977 | \& ev_stat_start (loop, &passwd); |
2473 | \& ev_timer_init (&timer, timer_cb, 0., 1.02); |
2978 | \& ev_timer_init (&timer, timer_cb, 0., 1.02); |
2474 | .Ve |
2979 | .Ve |
2475 | .ie n .Sh """ev_idle"" \- when you've got nothing better to do..." |
2980 | .ie n .SS """ev_idle"" \- when you've got nothing better to do..." |
2476 | .el .Sh "\f(CWev_idle\fP \- when you've got nothing better to do..." |
2981 | .el .SS "\f(CWev_idle\fP \- when you've got nothing better to do..." |
2477 | .IX Subsection "ev_idle - when you've got nothing better to do..." |
2982 | .IX Subsection "ev_idle - when you've got nothing better to do..." |
2478 | Idle watchers trigger events when no other events of the same or higher |
2983 | Idle watchers trigger events when no other events of the same or higher |
2479 | priority are pending (prepare, check and other idle watchers do not count |
2984 | priority are pending (prepare, check and other idle watchers do not count |
2480 | as receiving \*(L"events\*(R"). |
2985 | as receiving \*(L"events\*(R"). |
2481 | .PP |
2986 | .PP |
… | |
… | |
2491 | .PP |
2996 | .PP |
2492 | Apart from keeping your process non-blocking (which is a useful |
2997 | Apart from keeping your process non-blocking (which is a useful |
2493 | effect on its own sometimes), idle watchers are a good place to do |
2998 | effect on its own sometimes), idle watchers are a good place to do |
2494 | \&\*(L"pseudo-background processing\*(R", or delay processing stuff to after the |
2999 | \&\*(L"pseudo-background processing\*(R", or delay processing stuff to after the |
2495 | event loop has handled all outstanding events. |
3000 | event loop has handled all outstanding events. |
|
|
3001 | .PP |
|
|
3002 | \fIAbusing an \f(CI\*(C`ev_idle\*(C'\fI watcher for its side-effect\fR |
|
|
3003 | .IX Subsection "Abusing an ev_idle watcher for its side-effect" |
|
|
3004 | .PP |
|
|
3005 | As long as there is at least one active idle watcher, libev will never |
|
|
3006 | sleep unnecessarily. Or in other words, it will loop as fast as possible. |
|
|
3007 | For this to work, the idle watcher doesn't need to be invoked at all \- the |
|
|
3008 | lowest priority will do. |
|
|
3009 | .PP |
|
|
3010 | This mode of operation can be useful together with an \f(CW\*(C`ev_check\*(C'\fR watcher, |
|
|
3011 | to do something on each event loop iteration \- for example to balance load |
|
|
3012 | between different connections. |
|
|
3013 | .PP |
|
|
3014 | See \*(L"Abusing an ev_check watcher for its side-effect\*(R" for a longer |
|
|
3015 | example. |
2496 | .PP |
3016 | .PP |
2497 | \fIWatcher-Specific Functions and Data Members\fR |
3017 | \fIWatcher-Specific Functions and Data Members\fR |
2498 | .IX Subsection "Watcher-Specific Functions and Data Members" |
3018 | .IX Subsection "Watcher-Specific Functions and Data Members" |
2499 | .IP "ev_idle_init (ev_idle *, callback)" 4 |
3019 | .IP "ev_idle_init (ev_idle *, callback)" 4 |
2500 | .IX Item "ev_idle_init (ev_idle *, callback)" |
3020 | .IX Item "ev_idle_init (ev_idle *, callback)" |
… | |
… | |
2506 | .IX Subsection "Examples" |
3026 | .IX Subsection "Examples" |
2507 | .PP |
3027 | .PP |
2508 | Example: Dynamically allocate an \f(CW\*(C`ev_idle\*(C'\fR watcher, start it, and in the |
3028 | Example: Dynamically allocate an \f(CW\*(C`ev_idle\*(C'\fR watcher, start it, and in the |
2509 | callback, free it. Also, use no error checking, as usual. |
3029 | callback, free it. Also, use no error checking, as usual. |
2510 | .PP |
3030 | .PP |
2511 | .Vb 7 |
3031 | .Vb 5 |
2512 | \& static void |
3032 | \& static void |
2513 | \& idle_cb (struct ev_loop *loop, ev_idle *w, int revents) |
3033 | \& idle_cb (struct ev_loop *loop, ev_idle *w, int revents) |
2514 | \& { |
3034 | \& { |
|
|
3035 | \& // stop the watcher |
|
|
3036 | \& ev_idle_stop (loop, w); |
|
|
3037 | \& |
|
|
3038 | \& // now we can free it |
2515 | \& free (w); |
3039 | \& free (w); |
|
|
3040 | \& |
2516 | \& // now do something you wanted to do when the program has |
3041 | \& // now do something you wanted to do when the program has |
2517 | \& // no longer anything immediate to do. |
3042 | \& // no longer anything immediate to do. |
2518 | \& } |
3043 | \& } |
2519 | \& |
3044 | \& |
2520 | \& ev_idle *idle_watcher = malloc (sizeof (ev_idle)); |
3045 | \& ev_idle *idle_watcher = malloc (sizeof (ev_idle)); |
2521 | \& ev_idle_init (idle_watcher, idle_cb); |
3046 | \& ev_idle_init (idle_watcher, idle_cb); |
2522 | \& ev_idle_start (loop, idle_cb); |
3047 | \& ev_idle_start (loop, idle_watcher); |
2523 | .Ve |
3048 | .Ve |
2524 | .ie n .Sh """ev_prepare""\fP and \f(CW""ev_check"" \- customise your event loop!" |
3049 | .ie n .SS """ev_prepare"" and ""ev_check"" \- customise your event loop!" |
2525 | .el .Sh "\f(CWev_prepare\fP and \f(CWev_check\fP \- customise your event loop!" |
3050 | .el .SS "\f(CWev_prepare\fP and \f(CWev_check\fP \- customise your event loop!" |
2526 | .IX Subsection "ev_prepare and ev_check - customise your event loop!" |
3051 | .IX Subsection "ev_prepare and ev_check - customise your event loop!" |
2527 | Prepare and check watchers are usually (but not always) used in pairs: |
3052 | Prepare and check watchers are often (but not always) used in pairs: |
2528 | prepare watchers get invoked before the process blocks and check watchers |
3053 | prepare watchers get invoked before the process blocks and check watchers |
2529 | afterwards. |
3054 | afterwards. |
2530 | .PP |
3055 | .PP |
2531 | You \fImust not\fR call \f(CW\*(C`ev_loop\*(C'\fR or similar functions that enter |
3056 | You \fImust not\fR call \f(CW\*(C`ev_run\*(C'\fR (or similar functions that enter the |
2532 | the current event loop from either \f(CW\*(C`ev_prepare\*(C'\fR or \f(CW\*(C`ev_check\*(C'\fR |
3057 | current event loop) or \f(CW\*(C`ev_loop_fork\*(C'\fR from either \f(CW\*(C`ev_prepare\*(C'\fR or |
2533 | watchers. Other loops than the current one are fine, however. The |
3058 | \&\f(CW\*(C`ev_check\*(C'\fR watchers. Other loops than the current one are fine, |
2534 | rationale behind this is that you do not need to check for recursion in |
3059 | however. The rationale behind this is that you do not need to check |
2535 | those watchers, i.e. the sequence will always be \f(CW\*(C`ev_prepare\*(C'\fR, blocking, |
3060 | for recursion in those watchers, i.e. the sequence will always be |
2536 | \&\f(CW\*(C`ev_check\*(C'\fR so if you have one watcher of each kind they will always be |
3061 | \&\f(CW\*(C`ev_prepare\*(C'\fR, blocking, \f(CW\*(C`ev_check\*(C'\fR so if you have one watcher of each |
2537 | called in pairs bracketing the blocking call. |
3062 | kind they will always be called in pairs bracketing the blocking call. |
2538 | .PP |
3063 | .PP |
2539 | Their main purpose is to integrate other event mechanisms into libev and |
3064 | Their main purpose is to integrate other event mechanisms into libev and |
2540 | their use is somewhat advanced. They could be used, for example, to track |
3065 | their use is somewhat advanced. They could be used, for example, to track |
2541 | variable changes, implement your own watchers, integrate net-snmp or a |
3066 | variable changes, implement your own watchers, integrate net-snmp or a |
2542 | coroutine library and lots more. They are also occasionally useful if |
3067 | coroutine library and lots more. They are also occasionally useful if |
… | |
… | |
2560 | with priority higher than or equal to the event loop and one coroutine |
3085 | with priority higher than or equal to the event loop and one coroutine |
2561 | of lower priority, but only once, using idle watchers to keep the event |
3086 | of lower priority, but only once, using idle watchers to keep the event |
2562 | loop from blocking if lower-priority coroutines are active, thus mapping |
3087 | loop from blocking if lower-priority coroutines are active, thus mapping |
2563 | low-priority coroutines to idle/background tasks). |
3088 | low-priority coroutines to idle/background tasks). |
2564 | .PP |
3089 | .PP |
2565 | It is recommended to give \f(CW\*(C`ev_check\*(C'\fR watchers highest (\f(CW\*(C`EV_MAXPRI\*(C'\fR) |
3090 | When used for this purpose, it is recommended to give \f(CW\*(C`ev_check\*(C'\fR watchers |
2566 | priority, to ensure that they are being run before any other watchers |
3091 | highest (\f(CW\*(C`EV_MAXPRI\*(C'\fR) priority, to ensure that they are being run before |
2567 | after the poll (this doesn't matter for \f(CW\*(C`ev_prepare\*(C'\fR watchers). |
3092 | any other watchers after the poll (this doesn't matter for \f(CW\*(C`ev_prepare\*(C'\fR |
|
|
3093 | watchers). |
2568 | .PP |
3094 | .PP |
2569 | Also, \f(CW\*(C`ev_check\*(C'\fR watchers (and \f(CW\*(C`ev_prepare\*(C'\fR watchers, too) should not |
3095 | Also, \f(CW\*(C`ev_check\*(C'\fR watchers (and \f(CW\*(C`ev_prepare\*(C'\fR watchers, too) should not |
2570 | activate (\*(L"feed\*(R") events into libev. While libev fully supports this, they |
3096 | activate (\*(L"feed\*(R") events into libev. While libev fully supports this, they |
2571 | might get executed before other \f(CW\*(C`ev_check\*(C'\fR watchers did their job. As |
3097 | might get executed before other \f(CW\*(C`ev_check\*(C'\fR watchers did their job. As |
2572 | \&\f(CW\*(C`ev_check\*(C'\fR watchers are often used to embed other (non-libev) event |
3098 | \&\f(CW\*(C`ev_check\*(C'\fR watchers are often used to embed other (non-libev) event |
2573 | loops those other event loops might be in an unusable state until their |
3099 | loops those other event loops might be in an unusable state until their |
2574 | \&\f(CW\*(C`ev_check\*(C'\fR watcher ran (always remind yourself to coexist peacefully with |
3100 | \&\f(CW\*(C`ev_check\*(C'\fR watcher ran (always remind yourself to coexist peacefully with |
2575 | others). |
3101 | others). |
|
|
3102 | .PP |
|
|
3103 | \fIAbusing an \f(CI\*(C`ev_check\*(C'\fI watcher for its side-effect\fR |
|
|
3104 | .IX Subsection "Abusing an ev_check watcher for its side-effect" |
|
|
3105 | .PP |
|
|
3106 | \&\f(CW\*(C`ev_check\*(C'\fR (and less often also \f(CW\*(C`ev_prepare\*(C'\fR) watchers can also be |
|
|
3107 | useful because they are called once per event loop iteration. For |
|
|
3108 | example, if you want to handle a large number of connections fairly, you |
|
|
3109 | normally only do a bit of work for each active connection, and if there |
|
|
3110 | is more work to do, you wait for the next event loop iteration, so other |
|
|
3111 | connections have a chance of making progress. |
|
|
3112 | .PP |
|
|
3113 | Using an \f(CW\*(C`ev_check\*(C'\fR watcher is almost enough: it will be called on the |
|
|
3114 | next event loop iteration. However, that isn't as soon as possible \- |
|
|
3115 | without external events, your \f(CW\*(C`ev_check\*(C'\fR watcher will not be invoked. |
|
|
3116 | .PP |
|
|
3117 | This is where \f(CW\*(C`ev_idle\*(C'\fR watchers come in handy \- all you need is a |
|
|
3118 | single global idle watcher that is active as long as you have one active |
|
|
3119 | \&\f(CW\*(C`ev_check\*(C'\fR watcher. The \f(CW\*(C`ev_idle\*(C'\fR watcher makes sure the event loop |
|
|
3120 | will not sleep, and the \f(CW\*(C`ev_check\*(C'\fR watcher makes sure a callback gets |
|
|
3121 | invoked. Neither watcher alone can do that. |
2576 | .PP |
3122 | .PP |
2577 | \fIWatcher-Specific Functions and Data Members\fR |
3123 | \fIWatcher-Specific Functions and Data Members\fR |
2578 | .IX Subsection "Watcher-Specific Functions and Data Members" |
3124 | .IX Subsection "Watcher-Specific Functions and Data Members" |
2579 | .IP "ev_prepare_init (ev_prepare *, callback)" 4 |
3125 | .IP "ev_prepare_init (ev_prepare *, callback)" 4 |
2580 | .IX Item "ev_prepare_init (ev_prepare *, callback)" |
3126 | .IX Item "ev_prepare_init (ev_prepare *, callback)" |
… | |
… | |
2620 | \& struct pollfd fds [nfd]; |
3166 | \& struct pollfd fds [nfd]; |
2621 | \& // actual code will need to loop here and realloc etc. |
3167 | \& // actual code will need to loop here and realloc etc. |
2622 | \& adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
3168 | \& adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
2623 | \& |
3169 | \& |
2624 | \& /* the callback is illegal, but won\*(Aqt be called as we stop during check */ |
3170 | \& /* the callback is illegal, but won\*(Aqt be called as we stop during check */ |
2625 | \& ev_timer_init (&tw, 0, timeout * 1e\-3); |
3171 | \& ev_timer_init (&tw, 0, timeout * 1e\-3, 0.); |
2626 | \& ev_timer_start (loop, &tw); |
3172 | \& ev_timer_start (loop, &tw); |
2627 | \& |
3173 | \& |
2628 | \& // create one ev_io per pollfd |
3174 | \& // create one ev_io per pollfd |
2629 | \& for (int i = 0; i < nfd; ++i) |
3175 | \& for (int i = 0; i < nfd; ++i) |
2630 | \& { |
3176 | \& { |
… | |
… | |
2691 | .Ve |
3237 | .Ve |
2692 | .PP |
3238 | .PP |
2693 | Method 4: Do not use a prepare or check watcher because the module you |
3239 | Method 4: Do not use a prepare or check watcher because the module you |
2694 | want to embed is not flexible enough to support it. Instead, you can |
3240 | want to embed is not flexible enough to support it. Instead, you can |
2695 | override their poll function. The drawback with this solution is that the |
3241 | override their poll function. The drawback with this solution is that the |
2696 | main loop is now no longer controllable by \s-1EV\s0. The \f(CW\*(C`Glib::EV\*(C'\fR module uses |
3242 | main loop is now no longer controllable by \s-1EV.\s0 The \f(CW\*(C`Glib::EV\*(C'\fR module uses |
2697 | this approach, effectively embedding \s-1EV\s0 as a client into the horrible |
3243 | this approach, effectively embedding \s-1EV\s0 as a client into the horrible |
2698 | libglib event loop. |
3244 | libglib event loop. |
2699 | .PP |
3245 | .PP |
2700 | .Vb 4 |
3246 | .Vb 4 |
2701 | \& static gint |
3247 | \& static gint |
… | |
… | |
2708 | \& |
3254 | \& |
2709 | \& if (timeout >= 0) |
3255 | \& if (timeout >= 0) |
2710 | \& // create/start timer |
3256 | \& // create/start timer |
2711 | \& |
3257 | \& |
2712 | \& // poll |
3258 | \& // poll |
2713 | \& ev_loop (EV_A_ 0); |
3259 | \& ev_run (EV_A_ 0); |
2714 | \& |
3260 | \& |
2715 | \& // stop timer again |
3261 | \& // stop timer again |
2716 | \& if (timeout >= 0) |
3262 | \& if (timeout >= 0) |
2717 | \& ev_timer_stop (EV_A_ &to); |
3263 | \& ev_timer_stop (EV_A_ &to); |
2718 | \& |
3264 | \& |
… | |
… | |
2721 | \& ev_io_stop (EV_A_ iow [n]); |
3267 | \& ev_io_stop (EV_A_ iow [n]); |
2722 | \& |
3268 | \& |
2723 | \& return got_events; |
3269 | \& return got_events; |
2724 | \& } |
3270 | \& } |
2725 | .Ve |
3271 | .Ve |
2726 | .ie n .Sh """ev_embed"" \- when one backend isn't enough..." |
3272 | .ie n .SS """ev_embed"" \- when one backend isn't enough..." |
2727 | .el .Sh "\f(CWev_embed\fP \- when one backend isn't enough..." |
3273 | .el .SS "\f(CWev_embed\fP \- when one backend isn't enough..." |
2728 | .IX Subsection "ev_embed - when one backend isn't enough..." |
3274 | .IX Subsection "ev_embed - when one backend isn't enough..." |
2729 | This is a rather advanced watcher type that lets you embed one event loop |
3275 | This is a rather advanced watcher type that lets you embed one event loop |
2730 | into another (currently only \f(CW\*(C`ev_io\*(C'\fR events are supported in the embedded |
3276 | into another (currently only \f(CW\*(C`ev_io\*(C'\fR events are supported in the embedded |
2731 | loop, other types of watchers might be handled in a delayed or incorrect |
3277 | loop, other types of watchers might be handled in a delayed or incorrect |
2732 | fashion and must not be used). |
3278 | fashion and must not be used). |
… | |
… | |
2785 | \fIWatcher-Specific Functions and Data Members\fR |
3331 | \fIWatcher-Specific Functions and Data Members\fR |
2786 | .IX Subsection "Watcher-Specific Functions and Data Members" |
3332 | .IX Subsection "Watcher-Specific Functions and Data Members" |
2787 | .IP "ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)" 4 |
3333 | .IP "ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)" 4 |
2788 | .IX Item "ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)" |
3334 | .IX Item "ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)" |
2789 | .PD 0 |
3335 | .PD 0 |
2790 | .IP "ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)" 4 |
3336 | .IP "ev_embed_set (ev_embed *, struct ev_loop *embedded_loop)" 4 |
2791 | .IX Item "ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)" |
3337 | .IX Item "ev_embed_set (ev_embed *, struct ev_loop *embedded_loop)" |
2792 | .PD |
3338 | .PD |
2793 | Configures the watcher to embed the given loop, which must be |
3339 | Configures the watcher to embed the given loop, which must be |
2794 | embeddable. If the callback is \f(CW0\fR, then \f(CW\*(C`ev_embed_sweep\*(C'\fR will be |
3340 | embeddable. If the callback is \f(CW0\fR, then \f(CW\*(C`ev_embed_sweep\*(C'\fR will be |
2795 | invoked automatically, otherwise it is the responsibility of the callback |
3341 | invoked automatically, otherwise it is the responsibility of the callback |
2796 | to invoke it (it will continue to be called until the sweep has been done, |
3342 | to invoke it (it will continue to be called until the sweep has been done, |
2797 | if you do not want that, you need to temporarily stop the embed watcher). |
3343 | if you do not want that, you need to temporarily stop the embed watcher). |
2798 | .IP "ev_embed_sweep (loop, ev_embed *)" 4 |
3344 | .IP "ev_embed_sweep (loop, ev_embed *)" 4 |
2799 | .IX Item "ev_embed_sweep (loop, ev_embed *)" |
3345 | .IX Item "ev_embed_sweep (loop, ev_embed *)" |
2800 | Make a single, non-blocking sweep over the embedded loop. This works |
3346 | Make a single, non-blocking sweep over the embedded loop. This works |
2801 | similarly to \f(CW\*(C`ev_loop (embedded_loop, EVLOOP_NONBLOCK)\*(C'\fR, but in the most |
3347 | similarly to \f(CW\*(C`ev_run (embedded_loop, EVRUN_NOWAIT)\*(C'\fR, but in the most |
2802 | appropriate way for embedded loops. |
3348 | appropriate way for embedded loops. |
2803 | .IP "struct ev_loop *other [read\-only]" 4 |
3349 | .IP "struct ev_loop *other [read\-only]" 4 |
2804 | .IX Item "struct ev_loop *other [read-only]" |
3350 | .IX Item "struct ev_loop *other [read-only]" |
2805 | The embedded event loop. |
3351 | The embedded event loop. |
2806 | .PP |
3352 | .PP |
… | |
… | |
2815 | .PP |
3361 | .PP |
2816 | .Vb 3 |
3362 | .Vb 3 |
2817 | \& struct ev_loop *loop_hi = ev_default_init (0); |
3363 | \& struct ev_loop *loop_hi = ev_default_init (0); |
2818 | \& struct ev_loop *loop_lo = 0; |
3364 | \& struct ev_loop *loop_lo = 0; |
2819 | \& ev_embed embed; |
3365 | \& ev_embed embed; |
2820 | \& |
3366 | \& |
2821 | \& // see if there is a chance of getting one that works |
3367 | \& // see if there is a chance of getting one that works |
2822 | \& // (remember that a flags value of 0 means autodetection) |
3368 | \& // (remember that a flags value of 0 means autodetection) |
2823 | \& loop_lo = ev_embeddable_backends () & ev_recommended_backends () |
3369 | \& loop_lo = ev_embeddable_backends () & ev_recommended_backends () |
2824 | \& ? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ()) |
3370 | \& ? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ()) |
2825 | \& : 0; |
3371 | \& : 0; |
… | |
… | |
2841 | .PP |
3387 | .PP |
2842 | .Vb 3 |
3388 | .Vb 3 |
2843 | \& struct ev_loop *loop = ev_default_init (0); |
3389 | \& struct ev_loop *loop = ev_default_init (0); |
2844 | \& struct ev_loop *loop_socket = 0; |
3390 | \& struct ev_loop *loop_socket = 0; |
2845 | \& ev_embed embed; |
3391 | \& ev_embed embed; |
2846 | \& |
3392 | \& |
2847 | \& if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE) |
3393 | \& if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE) |
2848 | \& if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE)) |
3394 | \& if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE)) |
2849 | \& { |
3395 | \& { |
2850 | \& ev_embed_init (&embed, 0, loop_socket); |
3396 | \& ev_embed_init (&embed, 0, loop_socket); |
2851 | \& ev_embed_start (loop, &embed); |
3397 | \& ev_embed_start (loop, &embed); |
… | |
… | |
2854 | \& if (!loop_socket) |
3400 | \& if (!loop_socket) |
2855 | \& loop_socket = loop; |
3401 | \& loop_socket = loop; |
2856 | \& |
3402 | \& |
2857 | \& // now use loop_socket for all sockets, and loop for everything else |
3403 | \& // now use loop_socket for all sockets, and loop for everything else |
2858 | .Ve |
3404 | .Ve |
2859 | .ie n .Sh """ev_fork"" \- the audacity to resume the event loop after a fork" |
3405 | .ie n .SS """ev_fork"" \- the audacity to resume the event loop after a fork" |
2860 | .el .Sh "\f(CWev_fork\fP \- the audacity to resume the event loop after a fork" |
3406 | .el .SS "\f(CWev_fork\fP \- the audacity to resume the event loop after a fork" |
2861 | .IX Subsection "ev_fork - the audacity to resume the event loop after a fork" |
3407 | .IX Subsection "ev_fork - the audacity to resume the event loop after a fork" |
2862 | Fork watchers are called when a \f(CW\*(C`fork ()\*(C'\fR was detected (usually because |
3408 | Fork watchers are called when a \f(CW\*(C`fork ()\*(C'\fR was detected (usually because |
2863 | whoever is a good citizen cared to tell libev about it by calling |
3409 | whoever is a good citizen cared to tell libev about it by calling |
2864 | \&\f(CW\*(C`ev_default_fork\*(C'\fR or \f(CW\*(C`ev_loop_fork\*(C'\fR). The invocation is done before the |
3410 | \&\f(CW\*(C`ev_loop_fork\*(C'\fR). The invocation is done before the event loop blocks next |
2865 | event loop blocks next and before \f(CW\*(C`ev_check\*(C'\fR watchers are being called, |
3411 | and before \f(CW\*(C`ev_check\*(C'\fR watchers are being called, and only in the child |
2866 | and only in the child after the fork. If whoever good citizen calling |
3412 | after the fork. If whoever good citizen calling \f(CW\*(C`ev_default_fork\*(C'\fR cheats |
2867 | \&\f(CW\*(C`ev_default_fork\*(C'\fR cheats and calls it in the wrong process, the fork |
3413 | and calls it in the wrong process, the fork handlers will be invoked, too, |
2868 | handlers will be invoked, too, of course. |
3414 | of course. |
2869 | .PP |
3415 | .PP |
2870 | \fIThe special problem of life after fork \- how is it possible?\fR |
3416 | \fIThe special problem of life after fork \- how is it possible?\fR |
2871 | .IX Subsection "The special problem of life after fork - how is it possible?" |
3417 | .IX Subsection "The special problem of life after fork - how is it possible?" |
2872 | .PP |
3418 | .PP |
2873 | Most uses of \f(CW\*(C`fork()\*(C'\fR consist of forking, then some simple calls to ste |
3419 | Most uses of \f(CW\*(C`fork ()\*(C'\fR consist of forking, then some simple calls to set |
2874 | up/change the process environment, followed by a call to \f(CW\*(C`exec()\*(C'\fR. This |
3420 | up/change the process environment, followed by a call to \f(CW\*(C`exec()\*(C'\fR. This |
2875 | sequence should be handled by libev without any problems. |
3421 | sequence should be handled by libev without any problems. |
2876 | .PP |
3422 | .PP |
2877 | This changes when the application actually wants to do event handling |
3423 | This changes when the application actually wants to do event handling |
2878 | in the child, or both parent in child, in effect \*(L"continuing\*(R" after the |
3424 | in the child, or both parent in child, in effect \*(L"continuing\*(R" after the |
… | |
… | |
2894 | disadvantage of having to use multiple event loops (which do not support |
3440 | disadvantage of having to use multiple event loops (which do not support |
2895 | signal watchers). |
3441 | signal watchers). |
2896 | .PP |
3442 | .PP |
2897 | When this is not possible, or you want to use the default loop for |
3443 | When this is not possible, or you want to use the default loop for |
2898 | other reasons, then in the process that wants to start \*(L"fresh\*(R", call |
3444 | other reasons, then in the process that wants to start \*(L"fresh\*(R", call |
2899 | \&\f(CW\*(C`ev_default_destroy ()\*(C'\fR followed by \f(CW\*(C`ev_default_loop (...)\*(C'\fR. Destroying |
3445 | \&\f(CW\*(C`ev_loop_destroy (EV_DEFAULT)\*(C'\fR followed by \f(CW\*(C`ev_default_loop (...)\*(C'\fR. |
2900 | the default loop will \*(L"orphan\*(R" (not stop) all registered watchers, so you |
3446 | Destroying the default loop will \*(L"orphan\*(R" (not stop) all registered |
2901 | have to be careful not to execute code that modifies those watchers. Note |
3447 | watchers, so you have to be careful not to execute code that modifies |
2902 | also that in that case, you have to re-register any signal watchers. |
3448 | those watchers. Note also that in that case, you have to re-register any |
|
|
3449 | signal watchers. |
2903 | .PP |
3450 | .PP |
2904 | \fIWatcher-Specific Functions and Data Members\fR |
3451 | \fIWatcher-Specific Functions and Data Members\fR |
2905 | .IX Subsection "Watcher-Specific Functions and Data Members" |
3452 | .IX Subsection "Watcher-Specific Functions and Data Members" |
2906 | .IP "ev_fork_init (ev_signal *, callback)" 4 |
3453 | .IP "ev_fork_init (ev_fork *, callback)" 4 |
2907 | .IX Item "ev_fork_init (ev_signal *, callback)" |
3454 | .IX Item "ev_fork_init (ev_fork *, callback)" |
2908 | Initialises and configures the fork watcher \- it has no parameters of any |
3455 | Initialises and configures the fork watcher \- it has no parameters of any |
2909 | kind. There is a \f(CW\*(C`ev_fork_set\*(C'\fR macro, but using it is utterly pointless, |
3456 | kind. There is a \f(CW\*(C`ev_fork_set\*(C'\fR macro, but using it is utterly pointless, |
2910 | believe me. |
3457 | really. |
|
|
3458 | .ie n .SS """ev_cleanup"" \- even the best things end" |
|
|
3459 | .el .SS "\f(CWev_cleanup\fP \- even the best things end" |
|
|
3460 | .IX Subsection "ev_cleanup - even the best things end" |
|
|
3461 | Cleanup watchers are called just before the event loop is being destroyed |
|
|
3462 | by a call to \f(CW\*(C`ev_loop_destroy\*(C'\fR. |
|
|
3463 | .PP |
|
|
3464 | While there is no guarantee that the event loop gets destroyed, cleanup |
|
|
3465 | watchers provide a convenient method to install cleanup hooks for your |
|
|
3466 | program, worker threads and so on \- you just to make sure to destroy the |
|
|
3467 | loop when you want them to be invoked. |
|
|
3468 | .PP |
|
|
3469 | Cleanup watchers are invoked in the same way as any other watcher. Unlike |
|
|
3470 | all other watchers, they do not keep a reference to the event loop (which |
|
|
3471 | makes a lot of sense if you think about it). Like all other watchers, you |
|
|
3472 | can call libev functions in the callback, except \f(CW\*(C`ev_cleanup_start\*(C'\fR. |
|
|
3473 | .PP |
|
|
3474 | \fIWatcher-Specific Functions and Data Members\fR |
|
|
3475 | .IX Subsection "Watcher-Specific Functions and Data Members" |
|
|
3476 | .IP "ev_cleanup_init (ev_cleanup *, callback)" 4 |
|
|
3477 | .IX Item "ev_cleanup_init (ev_cleanup *, callback)" |
|
|
3478 | Initialises and configures the cleanup watcher \- it has no parameters of |
|
|
3479 | any kind. There is a \f(CW\*(C`ev_cleanup_set\*(C'\fR macro, but using it is utterly |
|
|
3480 | pointless, I assure you. |
|
|
3481 | .PP |
|
|
3482 | Example: Register an atexit handler to destroy the default loop, so any |
|
|
3483 | cleanup functions are called. |
|
|
3484 | .PP |
|
|
3485 | .Vb 5 |
|
|
3486 | \& static void |
|
|
3487 | \& program_exits (void) |
|
|
3488 | \& { |
|
|
3489 | \& ev_loop_destroy (EV_DEFAULT_UC); |
|
|
3490 | \& } |
|
|
3491 | \& |
|
|
3492 | \& ... |
|
|
3493 | \& atexit (program_exits); |
|
|
3494 | .Ve |
2911 | .ie n .Sh """ev_async"" \- how to wake up another event loop" |
3495 | .ie n .SS """ev_async"" \- how to wake up an event loop" |
2912 | .el .Sh "\f(CWev_async\fP \- how to wake up another event loop" |
3496 | .el .SS "\f(CWev_async\fP \- how to wake up an event loop" |
2913 | .IX Subsection "ev_async - how to wake up another event loop" |
3497 | .IX Subsection "ev_async - how to wake up an event loop" |
2914 | In general, you cannot use an \f(CW\*(C`ev_loop\*(C'\fR from multiple threads or other |
3498 | In general, you cannot use an \f(CW\*(C`ev_loop\*(C'\fR from multiple threads or other |
2915 | asynchronous sources such as signal handlers (as opposed to multiple event |
3499 | asynchronous sources such as signal handlers (as opposed to multiple event |
2916 | loops \- those are of course safe to use in different threads). |
3500 | loops \- those are of course safe to use in different threads). |
2917 | .PP |
3501 | .PP |
2918 | Sometimes, however, you need to wake up another event loop you do not |
3502 | Sometimes, however, you need to wake up an event loop you do not control, |
2919 | control, for example because it belongs to another thread. This is what |
3503 | for example because it belongs to another thread. This is what \f(CW\*(C`ev_async\*(C'\fR |
2920 | \&\f(CW\*(C`ev_async\*(C'\fR watchers do: as long as the \f(CW\*(C`ev_async\*(C'\fR watcher is active, you |
3504 | watchers do: as long as the \f(CW\*(C`ev_async\*(C'\fR watcher is active, you can signal |
2921 | can signal it by calling \f(CW\*(C`ev_async_send\*(C'\fR, which is thread\- and signal |
3505 | it by calling \f(CW\*(C`ev_async_send\*(C'\fR, which is thread\- and signal safe. |
2922 | safe. |
|
|
2923 | .PP |
3506 | .PP |
2924 | This functionality is very similar to \f(CW\*(C`ev_signal\*(C'\fR watchers, as signals, |
3507 | This functionality is very similar to \f(CW\*(C`ev_signal\*(C'\fR watchers, as signals, |
2925 | too, are asynchronous in nature, and signals, too, will be compressed |
3508 | too, are asynchronous in nature, and signals, too, will be compressed |
2926 | (i.e. the number of callback invocations may be less than the number of |
3509 | (i.e. the number of callback invocations may be less than the number of |
2927 | \&\f(CW\*(C`ev_async_sent\*(C'\fR calls). |
3510 | \&\f(CW\*(C`ev_async_send\*(C'\fR calls). In fact, you could use signal watchers as a kind |
2928 | .PP |
3511 | of \*(L"global async watchers\*(R" by using a watcher on an otherwise unused |
2929 | Unlike \f(CW\*(C`ev_signal\*(C'\fR watchers, \f(CW\*(C`ev_async\*(C'\fR works with any event loop, not |
3512 | signal, and \f(CW\*(C`ev_feed_signal\*(C'\fR to signal this watcher from another thread, |
2930 | just the default loop. |
3513 | even without knowing which loop owns the signal. |
2931 | .PP |
3514 | .PP |
2932 | \fIQueueing\fR |
3515 | \fIQueueing\fR |
2933 | .IX Subsection "Queueing" |
3516 | .IX Subsection "Queueing" |
2934 | .PP |
3517 | .PP |
2935 | \&\f(CW\*(C`ev_async\*(C'\fR does not support queueing of data in any way. The reason |
3518 | \&\f(CW\*(C`ev_async\*(C'\fR does not support queueing of data in any way. The reason |
2936 | is that the author does not know of a simple (or any) algorithm for a |
3519 | is that the author does not know of a simple (or any) algorithm for a |
2937 | multiple-writer-single-reader queue that works in all cases and doesn't |
3520 | multiple-writer-single-reader queue that works in all cases and doesn't |
2938 | need elaborate support such as pthreads. |
3521 | need elaborate support such as pthreads or unportable memory access |
|
|
3522 | semantics. |
2939 | .PP |
3523 | .PP |
2940 | That means that if you want to queue data, you have to provide your own |
3524 | That means that if you want to queue data, you have to provide your own |
2941 | queue. But at least I can tell you how to implement locking around your |
3525 | queue. But at least I can tell you how to implement locking around your |
2942 | queue: |
3526 | queue: |
2943 | .IP "queueing from a signal handler context" 4 |
3527 | .IP "queueing from a signal handler context" 4 |
… | |
… | |
3021 | kind. There is a \f(CW\*(C`ev_async_set\*(C'\fR macro, but using it is utterly pointless, |
3605 | kind. There is a \f(CW\*(C`ev_async_set\*(C'\fR macro, but using it is utterly pointless, |
3022 | trust me. |
3606 | trust me. |
3023 | .IP "ev_async_send (loop, ev_async *)" 4 |
3607 | .IP "ev_async_send (loop, ev_async *)" 4 |
3024 | .IX Item "ev_async_send (loop, ev_async *)" |
3608 | .IX Item "ev_async_send (loop, ev_async *)" |
3025 | Sends/signals/activates the given \f(CW\*(C`ev_async\*(C'\fR watcher, that is, feeds |
3609 | Sends/signals/activates the given \f(CW\*(C`ev_async\*(C'\fR watcher, that is, feeds |
3026 | an \f(CW\*(C`EV_ASYNC\*(C'\fR event on the watcher into the event loop. Unlike |
3610 | an \f(CW\*(C`EV_ASYNC\*(C'\fR event on the watcher into the event loop, and instantly |
|
|
3611 | returns. |
|
|
3612 | .Sp |
3027 | \&\f(CW\*(C`ev_feed_event\*(C'\fR, this call is safe to do from other threads, signal or |
3613 | Unlike \f(CW\*(C`ev_feed_event\*(C'\fR, this call is safe to do from other threads, |
3028 | similar contexts (see the discussion of \f(CW\*(C`EV_ATOMIC_T\*(C'\fR in the embedding |
3614 | signal or similar contexts (see the discussion of \f(CW\*(C`EV_ATOMIC_T\*(C'\fR in the |
3029 | section below on what exactly this means). |
3615 | embedding section below on what exactly this means). |
3030 | .Sp |
3616 | .Sp |
3031 | Note that, as with other watchers in libev, multiple events might get |
3617 | Note that, as with other watchers in libev, multiple events might get |
3032 | compressed into a single callback invocation (another way to look at this |
3618 | compressed into a single callback invocation (another way to look at |
3033 | is that \f(CW\*(C`ev_async\*(C'\fR watchers are level-triggered, set on \f(CW\*(C`ev_async_send\*(C'\fR, |
3619 | this is that \f(CW\*(C`ev_async\*(C'\fR watchers are level-triggered: they are set on |
3034 | reset when the event loop detects that). |
3620 | \&\f(CW\*(C`ev_async_send\*(C'\fR, reset when the event loop detects that). |
3035 | .Sp |
3621 | .Sp |
3036 | This call incurs the overhead of a system call only once per event loop |
3622 | This call incurs the overhead of at most one extra system call per event |
3037 | iteration, so while the overhead might be noticeable, it doesn't apply to |
3623 | loop iteration, if the event loop is blocked, and no syscall at all if |
3038 | repeated calls to \f(CW\*(C`ev_async_send\*(C'\fR for the same event loop. |
3624 | the event loop (or your program) is processing events. That means that |
|
|
3625 | repeated calls are basically free (there is no need to avoid calls for |
|
|
3626 | performance reasons) and that the overhead becomes smaller (typically |
|
|
3627 | zero) under load. |
3039 | .IP "bool = ev_async_pending (ev_async *)" 4 |
3628 | .IP "bool = ev_async_pending (ev_async *)" 4 |
3040 | .IX Item "bool = ev_async_pending (ev_async *)" |
3629 | .IX Item "bool = ev_async_pending (ev_async *)" |
3041 | Returns a non-zero value when \f(CW\*(C`ev_async_send\*(C'\fR has been called on the |
3630 | Returns a non-zero value when \f(CW\*(C`ev_async_send\*(C'\fR has been called on the |
3042 | watcher but the event has not yet been processed (or even noted) by the |
3631 | watcher but the event has not yet been processed (or even noted) by the |
3043 | event loop. |
3632 | event loop. |
… | |
… | |
3068 | .Sp |
3657 | .Sp |
3069 | If \f(CW\*(C`timeout\*(C'\fR is less than 0, then no timeout watcher will be |
3658 | If \f(CW\*(C`timeout\*(C'\fR is less than 0, then no timeout watcher will be |
3070 | started. Otherwise an \f(CW\*(C`ev_timer\*(C'\fR watcher with after = \f(CW\*(C`timeout\*(C'\fR (and |
3659 | started. Otherwise an \f(CW\*(C`ev_timer\*(C'\fR watcher with after = \f(CW\*(C`timeout\*(C'\fR (and |
3071 | repeat = 0) will be started. \f(CW0\fR is a valid timeout. |
3660 | repeat = 0) will be started. \f(CW0\fR is a valid timeout. |
3072 | .Sp |
3661 | .Sp |
3073 | The callback has the type \f(CW\*(C`void (*cb)(int revents, void *arg)\*(C'\fR and gets |
3662 | The callback has the type \f(CW\*(C`void (*cb)(int revents, void *arg)\*(C'\fR and is |
3074 | passed an \f(CW\*(C`revents\*(C'\fR set like normal event callbacks (a combination of |
3663 | passed an \f(CW\*(C`revents\*(C'\fR set like normal event callbacks (a combination of |
3075 | \&\f(CW\*(C`EV_ERROR\*(C'\fR, \f(CW\*(C`EV_READ\*(C'\fR, \f(CW\*(C`EV_WRITE\*(C'\fR or \f(CW\*(C`EV_TIMEOUT\*(C'\fR) and the \f(CW\*(C`arg\*(C'\fR |
3664 | \&\f(CW\*(C`EV_ERROR\*(C'\fR, \f(CW\*(C`EV_READ\*(C'\fR, \f(CW\*(C`EV_WRITE\*(C'\fR or \f(CW\*(C`EV_TIMER\*(C'\fR) and the \f(CW\*(C`arg\*(C'\fR |
3076 | value passed to \f(CW\*(C`ev_once\*(C'\fR. Note that it is possible to receive \fIboth\fR |
3665 | value passed to \f(CW\*(C`ev_once\*(C'\fR. Note that it is possible to receive \fIboth\fR |
3077 | a timeout and an io event at the same time \- you probably should give io |
3666 | a timeout and an io event at the same time \- you probably should give io |
3078 | events precedence. |
3667 | events precedence. |
3079 | .Sp |
3668 | .Sp |
3080 | Example: wait up to ten seconds for data to appear on \s-1STDIN_FILENO\s0. |
3669 | Example: wait up to ten seconds for data to appear on \s-1STDIN_FILENO.\s0 |
3081 | .Sp |
3670 | .Sp |
3082 | .Vb 7 |
3671 | .Vb 7 |
3083 | \& static void stdin_ready (int revents, void *arg) |
3672 | \& static void stdin_ready (int revents, void *arg) |
3084 | \& { |
3673 | \& { |
3085 | \& if (revents & EV_READ) |
3674 | \& if (revents & EV_READ) |
3086 | \& /* stdin might have data for us, joy! */; |
3675 | \& /* stdin might have data for us, joy! */; |
3087 | \& else if (revents & EV_TIMEOUT) |
3676 | \& else if (revents & EV_TIMER) |
3088 | \& /* doh, nothing entered */; |
3677 | \& /* doh, nothing entered */; |
3089 | \& } |
3678 | \& } |
3090 | \& |
3679 | \& |
3091 | \& ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
3680 | \& ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
3092 | .Ve |
3681 | .Ve |
3093 | .IP "ev_feed_event (struct ev_loop *, watcher *, int revents)" 4 |
|
|
3094 | .IX Item "ev_feed_event (struct ev_loop *, watcher *, int revents)" |
|
|
3095 | Feeds the given event set into the event loop, as if the specified event |
|
|
3096 | had happened for the specified watcher (which must be a pointer to an |
|
|
3097 | initialised but not necessarily started event watcher). |
|
|
3098 | .IP "ev_feed_fd_event (struct ev_loop *, int fd, int revents)" 4 |
3682 | .IP "ev_feed_fd_event (loop, int fd, int revents)" 4 |
3099 | .IX Item "ev_feed_fd_event (struct ev_loop *, int fd, int revents)" |
3683 | .IX Item "ev_feed_fd_event (loop, int fd, int revents)" |
3100 | Feed an event on the given fd, as if a file descriptor backend detected |
3684 | Feed an event on the given fd, as if a file descriptor backend detected |
3101 | the given events it. |
3685 | the given events. |
3102 | .IP "ev_feed_signal_event (struct ev_loop *loop, int signum)" 4 |
3686 | .IP "ev_feed_signal_event (loop, int signum)" 4 |
3103 | .IX Item "ev_feed_signal_event (struct ev_loop *loop, int signum)" |
3687 | .IX Item "ev_feed_signal_event (loop, int signum)" |
3104 | Feed an event as if the given signal occurred (\f(CW\*(C`loop\*(C'\fR must be the default |
3688 | Feed an event as if the given signal occurred. See also \f(CW\*(C`ev_feed_signal\*(C'\fR, |
3105 | loop!). |
3689 | which is async-safe. |
|
|
3690 | .SH "COMMON OR USEFUL IDIOMS (OR BOTH)" |
|
|
3691 | .IX Header "COMMON OR USEFUL IDIOMS (OR BOTH)" |
|
|
3692 | This section explains some common idioms that are not immediately |
|
|
3693 | obvious. Note that examples are sprinkled over the whole manual, and this |
|
|
3694 | section only contains stuff that wouldn't fit anywhere else. |
|
|
3695 | .SS "\s-1ASSOCIATING CUSTOM DATA WITH A WATCHER\s0" |
|
|
3696 | .IX Subsection "ASSOCIATING CUSTOM DATA WITH A WATCHER" |
|
|
3697 | Each watcher has, by default, a \f(CW\*(C`void *data\*(C'\fR member that you can read |
|
|
3698 | or modify at any time: libev will completely ignore it. This can be used |
|
|
3699 | to associate arbitrary data with your watcher. If you need more data and |
|
|
3700 | don't want to allocate memory separately and store a pointer to it in that |
|
|
3701 | data member, you can also \*(L"subclass\*(R" the watcher type and provide your own |
|
|
3702 | data: |
|
|
3703 | .PP |
|
|
3704 | .Vb 7 |
|
|
3705 | \& struct my_io |
|
|
3706 | \& { |
|
|
3707 | \& ev_io io; |
|
|
3708 | \& int otherfd; |
|
|
3709 | \& void *somedata; |
|
|
3710 | \& struct whatever *mostinteresting; |
|
|
3711 | \& }; |
|
|
3712 | \& |
|
|
3713 | \& ... |
|
|
3714 | \& struct my_io w; |
|
|
3715 | \& ev_io_init (&w.io, my_cb, fd, EV_READ); |
|
|
3716 | .Ve |
|
|
3717 | .PP |
|
|
3718 | And since your callback will be called with a pointer to the watcher, you |
|
|
3719 | can cast it back to your own type: |
|
|
3720 | .PP |
|
|
3721 | .Vb 5 |
|
|
3722 | \& static void my_cb (struct ev_loop *loop, ev_io *w_, int revents) |
|
|
3723 | \& { |
|
|
3724 | \& struct my_io *w = (struct my_io *)w_; |
|
|
3725 | \& ... |
|
|
3726 | \& } |
|
|
3727 | .Ve |
|
|
3728 | .PP |
|
|
3729 | More interesting and less C\-conformant ways of casting your callback |
|
|
3730 | function type instead have been omitted. |
|
|
3731 | .SS "\s-1BUILDING YOUR OWN COMPOSITE WATCHERS\s0" |
|
|
3732 | .IX Subsection "BUILDING YOUR OWN COMPOSITE WATCHERS" |
|
|
3733 | Another common scenario is to use some data structure with multiple |
|
|
3734 | embedded watchers, in effect creating your own watcher that combines |
|
|
3735 | multiple libev event sources into one \*(L"super-watcher\*(R": |
|
|
3736 | .PP |
|
|
3737 | .Vb 6 |
|
|
3738 | \& struct my_biggy |
|
|
3739 | \& { |
|
|
3740 | \& int some_data; |
|
|
3741 | \& ev_timer t1; |
|
|
3742 | \& ev_timer t2; |
|
|
3743 | \& } |
|
|
3744 | .Ve |
|
|
3745 | .PP |
|
|
3746 | In this case getting the pointer to \f(CW\*(C`my_biggy\*(C'\fR is a bit more |
|
|
3747 | complicated: Either you store the address of your \f(CW\*(C`my_biggy\*(C'\fR struct in |
|
|
3748 | the \f(CW\*(C`data\*(C'\fR member of the watcher (for woozies or \*(C+ coders), or you need |
|
|
3749 | to use some pointer arithmetic using \f(CW\*(C`offsetof\*(C'\fR inside your watchers (for |
|
|
3750 | real programmers): |
|
|
3751 | .PP |
|
|
3752 | .Vb 1 |
|
|
3753 | \& #include <stddef.h> |
|
|
3754 | \& |
|
|
3755 | \& static void |
|
|
3756 | \& t1_cb (EV_P_ ev_timer *w, int revents) |
|
|
3757 | \& { |
|
|
3758 | \& struct my_biggy big = (struct my_biggy *) |
|
|
3759 | \& (((char *)w) \- offsetof (struct my_biggy, t1)); |
|
|
3760 | \& } |
|
|
3761 | \& |
|
|
3762 | \& static void |
|
|
3763 | \& t2_cb (EV_P_ ev_timer *w, int revents) |
|
|
3764 | \& { |
|
|
3765 | \& struct my_biggy big = (struct my_biggy *) |
|
|
3766 | \& (((char *)w) \- offsetof (struct my_biggy, t2)); |
|
|
3767 | \& } |
|
|
3768 | .Ve |
|
|
3769 | .SS "\s-1AVOIDING FINISHING BEFORE RETURNING\s0" |
|
|
3770 | .IX Subsection "AVOIDING FINISHING BEFORE RETURNING" |
|
|
3771 | Often you have structures like this in event-based programs: |
|
|
3772 | .PP |
|
|
3773 | .Vb 4 |
|
|
3774 | \& callback () |
|
|
3775 | \& { |
|
|
3776 | \& free (request); |
|
|
3777 | \& } |
|
|
3778 | \& |
|
|
3779 | \& request = start_new_request (..., callback); |
|
|
3780 | .Ve |
|
|
3781 | .PP |
|
|
3782 | The intent is to start some \*(L"lengthy\*(R" operation. The \f(CW\*(C`request\*(C'\fR could be |
|
|
3783 | used to cancel the operation, or do other things with it. |
|
|
3784 | .PP |
|
|
3785 | It's not uncommon to have code paths in \f(CW\*(C`start_new_request\*(C'\fR that |
|
|
3786 | immediately invoke the callback, for example, to report errors. Or you add |
|
|
3787 | some caching layer that finds that it can skip the lengthy aspects of the |
|
|
3788 | operation and simply invoke the callback with the result. |
|
|
3789 | .PP |
|
|
3790 | The problem here is that this will happen \fIbefore\fR \f(CW\*(C`start_new_request\*(C'\fR |
|
|
3791 | has returned, so \f(CW\*(C`request\*(C'\fR is not set. |
|
|
3792 | .PP |
|
|
3793 | Even if you pass the request by some safer means to the callback, you |
|
|
3794 | might want to do something to the request after starting it, such as |
|
|
3795 | canceling it, which probably isn't working so well when the callback has |
|
|
3796 | already been invoked. |
|
|
3797 | .PP |
|
|
3798 | A common way around all these issues is to make sure that |
|
|
3799 | \&\f(CW\*(C`start_new_request\*(C'\fR \fIalways\fR returns before the callback is invoked. If |
|
|
3800 | \&\f(CW\*(C`start_new_request\*(C'\fR immediately knows the result, it can artificially |
|
|
3801 | delay invoking the callback by using a \f(CW\*(C`prepare\*(C'\fR or \f(CW\*(C`idle\*(C'\fR watcher for |
|
|
3802 | example, or more sneakily, by reusing an existing (stopped) watcher and |
|
|
3803 | pushing it into the pending queue: |
|
|
3804 | .PP |
|
|
3805 | .Vb 2 |
|
|
3806 | \& ev_set_cb (watcher, callback); |
|
|
3807 | \& ev_feed_event (EV_A_ watcher, 0); |
|
|
3808 | .Ve |
|
|
3809 | .PP |
|
|
3810 | This way, \f(CW\*(C`start_new_request\*(C'\fR can safely return before the callback is |
|
|
3811 | invoked, while not delaying callback invocation too much. |
|
|
3812 | .SS "\s-1MODEL/NESTED EVENT LOOP INVOCATIONS AND EXIT CONDITIONS\s0" |
|
|
3813 | .IX Subsection "MODEL/NESTED EVENT LOOP INVOCATIONS AND EXIT CONDITIONS" |
|
|
3814 | Often (especially in \s-1GUI\s0 toolkits) there are places where you have |
|
|
3815 | \&\fImodal\fR interaction, which is most easily implemented by recursively |
|
|
3816 | invoking \f(CW\*(C`ev_run\*(C'\fR. |
|
|
3817 | .PP |
|
|
3818 | This brings the problem of exiting \- a callback might want to finish the |
|
|
3819 | main \f(CW\*(C`ev_run\*(C'\fR call, but not the nested one (e.g. user clicked \*(L"Quit\*(R", but |
|
|
3820 | a modal \*(L"Are you sure?\*(R" dialog is still waiting), or just the nested one |
|
|
3821 | and not the main one (e.g. user clocked \*(L"Ok\*(R" in a modal dialog), or some |
|
|
3822 | other combination: In these cases, a simple \f(CW\*(C`ev_break\*(C'\fR will not work. |
|
|
3823 | .PP |
|
|
3824 | The solution is to maintain \*(L"break this loop\*(R" variable for each \f(CW\*(C`ev_run\*(C'\fR |
|
|
3825 | invocation, and use a loop around \f(CW\*(C`ev_run\*(C'\fR until the condition is |
|
|
3826 | triggered, using \f(CW\*(C`EVRUN_ONCE\*(C'\fR: |
|
|
3827 | .PP |
|
|
3828 | .Vb 2 |
|
|
3829 | \& // main loop |
|
|
3830 | \& int exit_main_loop = 0; |
|
|
3831 | \& |
|
|
3832 | \& while (!exit_main_loop) |
|
|
3833 | \& ev_run (EV_DEFAULT_ EVRUN_ONCE); |
|
|
3834 | \& |
|
|
3835 | \& // in a modal watcher |
|
|
3836 | \& int exit_nested_loop = 0; |
|
|
3837 | \& |
|
|
3838 | \& while (!exit_nested_loop) |
|
|
3839 | \& ev_run (EV_A_ EVRUN_ONCE); |
|
|
3840 | .Ve |
|
|
3841 | .PP |
|
|
3842 | To exit from any of these loops, just set the corresponding exit variable: |
|
|
3843 | .PP |
|
|
3844 | .Vb 2 |
|
|
3845 | \& // exit modal loop |
|
|
3846 | \& exit_nested_loop = 1; |
|
|
3847 | \& |
|
|
3848 | \& // exit main program, after modal loop is finished |
|
|
3849 | \& exit_main_loop = 1; |
|
|
3850 | \& |
|
|
3851 | \& // exit both |
|
|
3852 | \& exit_main_loop = exit_nested_loop = 1; |
|
|
3853 | .Ve |
|
|
3854 | .SS "\s-1THREAD LOCKING EXAMPLE\s0" |
|
|
3855 | .IX Subsection "THREAD LOCKING EXAMPLE" |
|
|
3856 | Here is a fictitious example of how to run an event loop in a different |
|
|
3857 | thread from where callbacks are being invoked and watchers are |
|
|
3858 | created/added/removed. |
|
|
3859 | .PP |
|
|
3860 | For a real-world example, see the \f(CW\*(C`EV::Loop::Async\*(C'\fR perl module, |
|
|
3861 | which uses exactly this technique (which is suited for many high-level |
|
|
3862 | languages). |
|
|
3863 | .PP |
|
|
3864 | The example uses a pthread mutex to protect the loop data, a condition |
|
|
3865 | variable to wait for callback invocations, an async watcher to notify the |
|
|
3866 | event loop thread and an unspecified mechanism to wake up the main thread. |
|
|
3867 | .PP |
|
|
3868 | First, you need to associate some data with the event loop: |
|
|
3869 | .PP |
|
|
3870 | .Vb 6 |
|
|
3871 | \& typedef struct { |
|
|
3872 | \& mutex_t lock; /* global loop lock */ |
|
|
3873 | \& ev_async async_w; |
|
|
3874 | \& thread_t tid; |
|
|
3875 | \& cond_t invoke_cv; |
|
|
3876 | \& } userdata; |
|
|
3877 | \& |
|
|
3878 | \& void prepare_loop (EV_P) |
|
|
3879 | \& { |
|
|
3880 | \& // for simplicity, we use a static userdata struct. |
|
|
3881 | \& static userdata u; |
|
|
3882 | \& |
|
|
3883 | \& ev_async_init (&u\->async_w, async_cb); |
|
|
3884 | \& ev_async_start (EV_A_ &u\->async_w); |
|
|
3885 | \& |
|
|
3886 | \& pthread_mutex_init (&u\->lock, 0); |
|
|
3887 | \& pthread_cond_init (&u\->invoke_cv, 0); |
|
|
3888 | \& |
|
|
3889 | \& // now associate this with the loop |
|
|
3890 | \& ev_set_userdata (EV_A_ u); |
|
|
3891 | \& ev_set_invoke_pending_cb (EV_A_ l_invoke); |
|
|
3892 | \& ev_set_loop_release_cb (EV_A_ l_release, l_acquire); |
|
|
3893 | \& |
|
|
3894 | \& // then create the thread running ev_run |
|
|
3895 | \& pthread_create (&u\->tid, 0, l_run, EV_A); |
|
|
3896 | \& } |
|
|
3897 | .Ve |
|
|
3898 | .PP |
|
|
3899 | The callback for the \f(CW\*(C`ev_async\*(C'\fR watcher does nothing: the watcher is used |
|
|
3900 | solely to wake up the event loop so it takes notice of any new watchers |
|
|
3901 | that might have been added: |
|
|
3902 | .PP |
|
|
3903 | .Vb 5 |
|
|
3904 | \& static void |
|
|
3905 | \& async_cb (EV_P_ ev_async *w, int revents) |
|
|
3906 | \& { |
|
|
3907 | \& // just used for the side effects |
|
|
3908 | \& } |
|
|
3909 | .Ve |
|
|
3910 | .PP |
|
|
3911 | The \f(CW\*(C`l_release\*(C'\fR and \f(CW\*(C`l_acquire\*(C'\fR callbacks simply unlock/lock the mutex |
|
|
3912 | protecting the loop data, respectively. |
|
|
3913 | .PP |
|
|
3914 | .Vb 6 |
|
|
3915 | \& static void |
|
|
3916 | \& l_release (EV_P) |
|
|
3917 | \& { |
|
|
3918 | \& userdata *u = ev_userdata (EV_A); |
|
|
3919 | \& pthread_mutex_unlock (&u\->lock); |
|
|
3920 | \& } |
|
|
3921 | \& |
|
|
3922 | \& static void |
|
|
3923 | \& l_acquire (EV_P) |
|
|
3924 | \& { |
|
|
3925 | \& userdata *u = ev_userdata (EV_A); |
|
|
3926 | \& pthread_mutex_lock (&u\->lock); |
|
|
3927 | \& } |
|
|
3928 | .Ve |
|
|
3929 | .PP |
|
|
3930 | The event loop thread first acquires the mutex, and then jumps straight |
|
|
3931 | into \f(CW\*(C`ev_run\*(C'\fR: |
|
|
3932 | .PP |
|
|
3933 | .Vb 4 |
|
|
3934 | \& void * |
|
|
3935 | \& l_run (void *thr_arg) |
|
|
3936 | \& { |
|
|
3937 | \& struct ev_loop *loop = (struct ev_loop *)thr_arg; |
|
|
3938 | \& |
|
|
3939 | \& l_acquire (EV_A); |
|
|
3940 | \& pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0); |
|
|
3941 | \& ev_run (EV_A_ 0); |
|
|
3942 | \& l_release (EV_A); |
|
|
3943 | \& |
|
|
3944 | \& return 0; |
|
|
3945 | \& } |
|
|
3946 | .Ve |
|
|
3947 | .PP |
|
|
3948 | Instead of invoking all pending watchers, the \f(CW\*(C`l_invoke\*(C'\fR callback will |
|
|
3949 | signal the main thread via some unspecified mechanism (signals? pipe |
|
|
3950 | writes? \f(CW\*(C`Async::Interrupt\*(C'\fR?) and then waits until all pending watchers |
|
|
3951 | have been called (in a while loop because a) spurious wakeups are possible |
|
|
3952 | and b) skipping inter-thread-communication when there are no pending |
|
|
3953 | watchers is very beneficial): |
|
|
3954 | .PP |
|
|
3955 | .Vb 4 |
|
|
3956 | \& static void |
|
|
3957 | \& l_invoke (EV_P) |
|
|
3958 | \& { |
|
|
3959 | \& userdata *u = ev_userdata (EV_A); |
|
|
3960 | \& |
|
|
3961 | \& while (ev_pending_count (EV_A)) |
|
|
3962 | \& { |
|
|
3963 | \& wake_up_other_thread_in_some_magic_or_not_so_magic_way (); |
|
|
3964 | \& pthread_cond_wait (&u\->invoke_cv, &u\->lock); |
|
|
3965 | \& } |
|
|
3966 | \& } |
|
|
3967 | .Ve |
|
|
3968 | .PP |
|
|
3969 | Now, whenever the main thread gets told to invoke pending watchers, it |
|
|
3970 | will grab the lock, call \f(CW\*(C`ev_invoke_pending\*(C'\fR and then signal the loop |
|
|
3971 | thread to continue: |
|
|
3972 | .PP |
|
|
3973 | .Vb 4 |
|
|
3974 | \& static void |
|
|
3975 | \& real_invoke_pending (EV_P) |
|
|
3976 | \& { |
|
|
3977 | \& userdata *u = ev_userdata (EV_A); |
|
|
3978 | \& |
|
|
3979 | \& pthread_mutex_lock (&u\->lock); |
|
|
3980 | \& ev_invoke_pending (EV_A); |
|
|
3981 | \& pthread_cond_signal (&u\->invoke_cv); |
|
|
3982 | \& pthread_mutex_unlock (&u\->lock); |
|
|
3983 | \& } |
|
|
3984 | .Ve |
|
|
3985 | .PP |
|
|
3986 | Whenever you want to start/stop a watcher or do other modifications to an |
|
|
3987 | event loop, you will now have to lock: |
|
|
3988 | .PP |
|
|
3989 | .Vb 2 |
|
|
3990 | \& ev_timer timeout_watcher; |
|
|
3991 | \& userdata *u = ev_userdata (EV_A); |
|
|
3992 | \& |
|
|
3993 | \& ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.); |
|
|
3994 | \& |
|
|
3995 | \& pthread_mutex_lock (&u\->lock); |
|
|
3996 | \& ev_timer_start (EV_A_ &timeout_watcher); |
|
|
3997 | \& ev_async_send (EV_A_ &u\->async_w); |
|
|
3998 | \& pthread_mutex_unlock (&u\->lock); |
|
|
3999 | .Ve |
|
|
4000 | .PP |
|
|
4001 | Note that sending the \f(CW\*(C`ev_async\*(C'\fR watcher is required because otherwise |
|
|
4002 | an event loop currently blocking in the kernel will have no knowledge |
|
|
4003 | about the newly added timer. By waking up the loop it will pick up any new |
|
|
4004 | watchers in the next event loop iteration. |
|
|
4005 | .SS "\s-1THREADS, COROUTINES, CONTINUATIONS, QUEUES... INSTEAD OF CALLBACKS\s0" |
|
|
4006 | .IX Subsection "THREADS, COROUTINES, CONTINUATIONS, QUEUES... INSTEAD OF CALLBACKS" |
|
|
4007 | While the overhead of a callback that e.g. schedules a thread is small, it |
|
|
4008 | is still an overhead. If you embed libev, and your main usage is with some |
|
|
4009 | kind of threads or coroutines, you might want to customise libev so that |
|
|
4010 | doesn't need callbacks anymore. |
|
|
4011 | .PP |
|
|
4012 | Imagine you have coroutines that you can switch to using a function |
|
|
4013 | \&\f(CW\*(C`switch_to (coro)\*(C'\fR, that libev runs in a coroutine called \f(CW\*(C`libev_coro\*(C'\fR |
|
|
4014 | and that due to some magic, the currently active coroutine is stored in a |
|
|
4015 | global called \f(CW\*(C`current_coro\*(C'\fR. Then you can build your own \*(L"wait for libev |
|
|
4016 | event\*(R" primitive by changing \f(CW\*(C`EV_CB_DECLARE\*(C'\fR and \f(CW\*(C`EV_CB_INVOKE\*(C'\fR (note |
|
|
4017 | the differing \f(CW\*(C`;\*(C'\fR conventions): |
|
|
4018 | .PP |
|
|
4019 | .Vb 2 |
|
|
4020 | \& #define EV_CB_DECLARE(type) struct my_coro *cb; |
|
|
4021 | \& #define EV_CB_INVOKE(watcher) switch_to ((watcher)\->cb) |
|
|
4022 | .Ve |
|
|
4023 | .PP |
|
|
4024 | That means instead of having a C callback function, you store the |
|
|
4025 | coroutine to switch to in each watcher, and instead of having libev call |
|
|
4026 | your callback, you instead have it switch to that coroutine. |
|
|
4027 | .PP |
|
|
4028 | A coroutine might now wait for an event with a function called |
|
|
4029 | \&\f(CW\*(C`wait_for_event\*(C'\fR. (the watcher needs to be started, as always, but it doesn't |
|
|
4030 | matter when, or whether the watcher is active or not when this function is |
|
|
4031 | called): |
|
|
4032 | .PP |
|
|
4033 | .Vb 6 |
|
|
4034 | \& void |
|
|
4035 | \& wait_for_event (ev_watcher *w) |
|
|
4036 | \& { |
|
|
4037 | \& ev_set_cb (w, current_coro); |
|
|
4038 | \& switch_to (libev_coro); |
|
|
4039 | \& } |
|
|
4040 | .Ve |
|
|
4041 | .PP |
|
|
4042 | That basically suspends the coroutine inside \f(CW\*(C`wait_for_event\*(C'\fR and |
|
|
4043 | continues the libev coroutine, which, when appropriate, switches back to |
|
|
4044 | this or any other coroutine. |
|
|
4045 | .PP |
|
|
4046 | You can do similar tricks if you have, say, threads with an event queue \- |
|
|
4047 | instead of storing a coroutine, you store the queue object and instead of |
|
|
4048 | switching to a coroutine, you push the watcher onto the queue and notify |
|
|
4049 | any waiters. |
|
|
4050 | .PP |
|
|
4051 | To embed libev, see \*(L"\s-1EMBEDDING\*(R"\s0, but in short, it's easiest to create two |
|
|
4052 | files, \fImy_ev.h\fR and \fImy_ev.c\fR that include the respective libev files: |
|
|
4053 | .PP |
|
|
4054 | .Vb 4 |
|
|
4055 | \& // my_ev.h |
|
|
4056 | \& #define EV_CB_DECLARE(type) struct my_coro *cb; |
|
|
4057 | \& #define EV_CB_INVOKE(watcher) switch_to ((watcher)\->cb); |
|
|
4058 | \& #include "../libev/ev.h" |
|
|
4059 | \& |
|
|
4060 | \& // my_ev.c |
|
|
4061 | \& #define EV_H "my_ev.h" |
|
|
4062 | \& #include "../libev/ev.c" |
|
|
4063 | .Ve |
|
|
4064 | .PP |
|
|
4065 | And then use \fImy_ev.h\fR when you would normally use \fIev.h\fR, and compile |
|
|
4066 | \&\fImy_ev.c\fR into your project. When properly specifying include paths, you |
|
|
4067 | can even use \fIev.h\fR as header file name directly. |
3106 | .SH "LIBEVENT EMULATION" |
4068 | .SH "LIBEVENT EMULATION" |
3107 | .IX Header "LIBEVENT EMULATION" |
4069 | .IX Header "LIBEVENT EMULATION" |
3108 | Libev offers a compatibility emulation layer for libevent. It cannot |
4070 | Libev offers a compatibility emulation layer for libevent. It cannot |
3109 | emulate the internals of libevent, so here are some usage hints: |
4071 | emulate the internals of libevent, so here are some usage hints: |
|
|
4072 | .IP "\(bu" 4 |
|
|
4073 | Only the libevent\-1.4.1\-beta \s-1API\s0 is being emulated. |
|
|
4074 | .Sp |
|
|
4075 | This was the newest libevent version available when libev was implemented, |
|
|
4076 | and is still mostly unchanged in 2010. |
3110 | .IP "\(bu" 4 |
4077 | .IP "\(bu" 4 |
3111 | Use it by including <event.h>, as usual. |
4078 | Use it by including <event.h>, as usual. |
3112 | .IP "\(bu" 4 |
4079 | .IP "\(bu" 4 |
3113 | The following members are fully supported: ev_base, ev_callback, |
4080 | The following members are fully supported: ev_base, ev_callback, |
3114 | ev_arg, ev_fd, ev_res, ev_events. |
4081 | ev_arg, ev_fd, ev_res, ev_events. |
… | |
… | |
3120 | Priorities are not currently supported. Initialising priorities |
4087 | Priorities are not currently supported. Initialising priorities |
3121 | will fail and all watchers will have the same priority, even though there |
4088 | will fail and all watchers will have the same priority, even though there |
3122 | is an ev_pri field. |
4089 | is an ev_pri field. |
3123 | .IP "\(bu" 4 |
4090 | .IP "\(bu" 4 |
3124 | In libevent, the last base created gets the signals, in libev, the |
4091 | In libevent, the last base created gets the signals, in libev, the |
3125 | first base created (== the default loop) gets the signals. |
4092 | base that registered the signal gets the signals. |
3126 | .IP "\(bu" 4 |
4093 | .IP "\(bu" 4 |
3127 | Other members are not supported. |
4094 | Other members are not supported. |
3128 | .IP "\(bu" 4 |
4095 | .IP "\(bu" 4 |
3129 | The libev emulation is \fInot\fR \s-1ABI\s0 compatible to libevent, you need |
4096 | The libev emulation is \fInot\fR \s-1ABI\s0 compatible to libevent, you need |
3130 | to use the libev header file and library. |
4097 | to use the libev header file and library. |
3131 | .SH "\*(C+ SUPPORT" |
4098 | .SH "\*(C+ SUPPORT" |
3132 | .IX Header " SUPPORT" |
4099 | .IX Header " SUPPORT" |
|
|
4100 | .SS "C \s-1API\s0" |
|
|
4101 | .IX Subsection "C API" |
|
|
4102 | The normal C \s-1API\s0 should work fine when used from \*(C+: both ev.h and the |
|
|
4103 | libev sources can be compiled as \*(C+. Therefore, code that uses the C \s-1API\s0 |
|
|
4104 | will work fine. |
|
|
4105 | .PP |
|
|
4106 | Proper exception specifications might have to be added to callbacks passed |
|
|
4107 | to libev: exceptions may be thrown only from watcher callbacks, all |
|
|
4108 | other callbacks (allocator, syserr, loop acquire/release and periodic |
|
|
4109 | reschedule callbacks) must not throw exceptions, and might need a \f(CW\*(C`throw |
|
|
4110 | ()\*(C'\fR specification. If you have code that needs to be compiled as both C |
|
|
4111 | and \*(C+ you can use the \f(CW\*(C`EV_THROW\*(C'\fR macro for this: |
|
|
4112 | .PP |
|
|
4113 | .Vb 6 |
|
|
4114 | \& static void |
|
|
4115 | \& fatal_error (const char *msg) EV_THROW |
|
|
4116 | \& { |
|
|
4117 | \& perror (msg); |
|
|
4118 | \& abort (); |
|
|
4119 | \& } |
|
|
4120 | \& |
|
|
4121 | \& ... |
|
|
4122 | \& ev_set_syserr_cb (fatal_error); |
|
|
4123 | .Ve |
|
|
4124 | .PP |
|
|
4125 | The only \s-1API\s0 functions that can currently throw exceptions are \f(CW\*(C`ev_run\*(C'\fR, |
|
|
4126 | \&\f(CW\*(C`ev_invoke\*(C'\fR, \f(CW\*(C`ev_invoke_pending\*(C'\fR and \f(CW\*(C`ev_loop_destroy\*(C'\fR (the latter |
|
|
4127 | because it runs cleanup watchers). |
|
|
4128 | .PP |
|
|
4129 | Throwing exceptions in watcher callbacks is only supported if libev itself |
|
|
4130 | is compiled with a \*(C+ compiler or your C and \*(C+ environments allow |
|
|
4131 | throwing exceptions through C libraries (most do). |
|
|
4132 | .SS "\*(C+ \s-1API\s0" |
|
|
4133 | .IX Subsection " API" |
3133 | Libev comes with some simplistic wrapper classes for \*(C+ that mainly allow |
4134 | Libev comes with some simplistic wrapper classes for \*(C+ that mainly allow |
3134 | you to use some convenience methods to start/stop watchers and also change |
4135 | you to use some convenience methods to start/stop watchers and also change |
3135 | the callback model to a model using method callbacks on objects. |
4136 | the callback model to a model using method callbacks on objects. |
3136 | .PP |
4137 | .PP |
3137 | To use it, |
4138 | To use it, |
… | |
… | |
3148 | Care has been taken to keep the overhead low. The only data member the \*(C+ |
4149 | Care has been taken to keep the overhead low. The only data member the \*(C+ |
3149 | classes add (compared to plain C\-style watchers) is the event loop pointer |
4150 | classes add (compared to plain C\-style watchers) is the event loop pointer |
3150 | that the watcher is associated with (or no additional members at all if |
4151 | that the watcher is associated with (or no additional members at all if |
3151 | you disable \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR when embedding libev). |
4152 | you disable \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR when embedding libev). |
3152 | .PP |
4153 | .PP |
3153 | Currently, functions, and static and non-static member functions can be |
4154 | Currently, functions, static and non-static member functions and classes |
3154 | used as callbacks. Other types should be easy to add as long as they only |
4155 | with \f(CW\*(C`operator ()\*(C'\fR can be used as callbacks. Other types should be easy |
3155 | need one additional pointer for context. If you need support for other |
4156 | to add as long as they only need one additional pointer for context. If |
3156 | types of functors please contact the author (preferably after implementing |
4157 | you need support for other types of functors please contact the author |
3157 | it). |
4158 | (preferably after implementing it). |
|
|
4159 | .PP |
|
|
4160 | For all this to work, your \*(C+ compiler either has to use the same calling |
|
|
4161 | conventions as your C compiler (for static member functions), or you have |
|
|
4162 | to embed libev and compile libev itself as \*(C+. |
3158 | .PP |
4163 | .PP |
3159 | Here is a list of things available in the \f(CW\*(C`ev\*(C'\fR namespace: |
4164 | Here is a list of things available in the \f(CW\*(C`ev\*(C'\fR namespace: |
3160 | .ie n .IP """ev::READ""\fR, \f(CW""ev::WRITE"" etc." 4 |
4165 | .ie n .IP """ev::READ"", ""ev::WRITE"" etc." 4 |
3161 | .el .IP "\f(CWev::READ\fR, \f(CWev::WRITE\fR etc." 4 |
4166 | .el .IP "\f(CWev::READ\fR, \f(CWev::WRITE\fR etc." 4 |
3162 | .IX Item "ev::READ, ev::WRITE etc." |
4167 | .IX Item "ev::READ, ev::WRITE etc." |
3163 | These are just enum values with the same values as the \f(CW\*(C`EV_READ\*(C'\fR etc. |
4168 | These are just enum values with the same values as the \f(CW\*(C`EV_READ\*(C'\fR etc. |
3164 | macros from \fIev.h\fR. |
4169 | macros from \fIev.h\fR. |
3165 | .ie n .IP """ev::tstamp""\fR, \f(CW""ev::now""" 4 |
4170 | .ie n .IP """ev::tstamp"", ""ev::now""" 4 |
3166 | .el .IP "\f(CWev::tstamp\fR, \f(CWev::now\fR" 4 |
4171 | .el .IP "\f(CWev::tstamp\fR, \f(CWev::now\fR" 4 |
3167 | .IX Item "ev::tstamp, ev::now" |
4172 | .IX Item "ev::tstamp, ev::now" |
3168 | Aliases to the same types/functions as with the \f(CW\*(C`ev_\*(C'\fR prefix. |
4173 | Aliases to the same types/functions as with the \f(CW\*(C`ev_\*(C'\fR prefix. |
3169 | .ie n .IP """ev::io""\fR, \f(CW""ev::timer""\fR, \f(CW""ev::periodic""\fR, \f(CW""ev::idle""\fR, \f(CW""ev::sig"" etc." 4 |
4174 | .ie n .IP """ev::io"", ""ev::timer"", ""ev::periodic"", ""ev::idle"", ""ev::sig"" etc." 4 |
3170 | .el .IP "\f(CWev::io\fR, \f(CWev::timer\fR, \f(CWev::periodic\fR, \f(CWev::idle\fR, \f(CWev::sig\fR etc." 4 |
4175 | .el .IP "\f(CWev::io\fR, \f(CWev::timer\fR, \f(CWev::periodic\fR, \f(CWev::idle\fR, \f(CWev::sig\fR etc." 4 |
3171 | .IX Item "ev::io, ev::timer, ev::periodic, ev::idle, ev::sig etc." |
4176 | .IX Item "ev::io, ev::timer, ev::periodic, ev::idle, ev::sig etc." |
3172 | For each \f(CW\*(C`ev_TYPE\*(C'\fR watcher in \fIev.h\fR there is a corresponding class of |
4177 | For each \f(CW\*(C`ev_TYPE\*(C'\fR watcher in \fIev.h\fR there is a corresponding class of |
3173 | the same name in the \f(CW\*(C`ev\*(C'\fR namespace, with the exception of \f(CW\*(C`ev_signal\*(C'\fR |
4178 | the same name in the \f(CW\*(C`ev\*(C'\fR namespace, with the exception of \f(CW\*(C`ev_signal\*(C'\fR |
3174 | which is called \f(CW\*(C`ev::sig\*(C'\fR to avoid clashes with the \f(CW\*(C`signal\*(C'\fR macro |
4179 | which is called \f(CW\*(C`ev::sig\*(C'\fR to avoid clashes with the \f(CW\*(C`signal\*(C'\fR macro |
3175 | defines by many implementations. |
4180 | defined by many implementations. |
3176 | .Sp |
4181 | .Sp |
3177 | All of those classes have these methods: |
4182 | All of those classes have these methods: |
3178 | .RS 4 |
4183 | .RS 4 |
3179 | .IP "ev::TYPE::TYPE ()" 4 |
4184 | .IP "ev::TYPE::TYPE ()" 4 |
3180 | .IX Item "ev::TYPE::TYPE ()" |
4185 | .IX Item "ev::TYPE::TYPE ()" |
3181 | .PD 0 |
4186 | .PD 0 |
3182 | .IP "ev::TYPE::TYPE (struct ev_loop *)" 4 |
4187 | .IP "ev::TYPE::TYPE (loop)" 4 |
3183 | .IX Item "ev::TYPE::TYPE (struct ev_loop *)" |
4188 | .IX Item "ev::TYPE::TYPE (loop)" |
3184 | .IP "ev::TYPE::~TYPE" 4 |
4189 | .IP "ev::TYPE::~TYPE" 4 |
3185 | .IX Item "ev::TYPE::~TYPE" |
4190 | .IX Item "ev::TYPE::~TYPE" |
3186 | .PD |
4191 | .PD |
3187 | The constructor (optionally) takes an event loop to associate the watcher |
4192 | The constructor (optionally) takes an event loop to associate the watcher |
3188 | with. If it is omitted, it will use \f(CW\*(C`EV_DEFAULT\*(C'\fR. |
4193 | with. If it is omitted, it will use \f(CW\*(C`EV_DEFAULT\*(C'\fR. |
… | |
… | |
3222 | \& ev::io iow; |
4227 | \& ev::io iow; |
3223 | \& iow.set <myclass, &myclass::io_cb> (&obj); |
4228 | \& iow.set <myclass, &myclass::io_cb> (&obj); |
3224 | .Ve |
4229 | .Ve |
3225 | .IP "w\->set (object *)" 4 |
4230 | .IP "w\->set (object *)" 4 |
3226 | .IX Item "w->set (object *)" |
4231 | .IX Item "w->set (object *)" |
3227 | This is an \fBexperimental\fR feature that might go away in a future version. |
|
|
3228 | .Sp |
|
|
3229 | This is a variation of a method callback \- leaving out the method to call |
4232 | This is a variation of a method callback \- leaving out the method to call |
3230 | will default the method to \f(CW\*(C`operator ()\*(C'\fR, which makes it possible to use |
4233 | will default the method to \f(CW\*(C`operator ()\*(C'\fR, which makes it possible to use |
3231 | functor objects without having to manually specify the \f(CW\*(C`operator ()\*(C'\fR all |
4234 | functor objects without having to manually specify the \f(CW\*(C`operator ()\*(C'\fR all |
3232 | the time. Incidentally, you can then also leave out the template argument |
4235 | the time. Incidentally, you can then also leave out the template argument |
3233 | list. |
4236 | list. |
… | |
… | |
3245 | \& void operator() (ev::io &w, int revents) |
4248 | \& void operator() (ev::io &w, int revents) |
3246 | \& { |
4249 | \& { |
3247 | \& ... |
4250 | \& ... |
3248 | \& } |
4251 | \& } |
3249 | \& } |
4252 | \& } |
3250 | \& |
4253 | \& |
3251 | \& myfunctor f; |
4254 | \& myfunctor f; |
3252 | \& |
4255 | \& |
3253 | \& ev::io w; |
4256 | \& ev::io w; |
3254 | \& w.set (&f); |
4257 | \& w.set (&f); |
3255 | .Ve |
4258 | .Ve |
… | |
… | |
3267 | .Sp |
4270 | .Sp |
3268 | .Vb 2 |
4271 | .Vb 2 |
3269 | \& static void io_cb (ev::io &w, int revents) { } |
4272 | \& static void io_cb (ev::io &w, int revents) { } |
3270 | \& iow.set <io_cb> (); |
4273 | \& iow.set <io_cb> (); |
3271 | .Ve |
4274 | .Ve |
3272 | .IP "w\->set (struct ev_loop *)" 4 |
4275 | .IP "w\->set (loop)" 4 |
3273 | .IX Item "w->set (struct ev_loop *)" |
4276 | .IX Item "w->set (loop)" |
3274 | Associates a different \f(CW\*(C`struct ev_loop\*(C'\fR with this watcher. You can only |
4277 | Associates a different \f(CW\*(C`struct ev_loop\*(C'\fR with this watcher. You can only |
3275 | do this when the watcher is inactive (and not pending either). |
4278 | do this when the watcher is inactive (and not pending either). |
3276 | .IP "w\->set ([arguments])" 4 |
4279 | .IP "w\->set ([arguments])" 4 |
3277 | .IX Item "w->set ([arguments])" |
4280 | .IX Item "w->set ([arguments])" |
3278 | Basically the same as \f(CW\*(C`ev_TYPE_set\*(C'\fR, with the same arguments. Must be |
4281 | Basically the same as \f(CW\*(C`ev_TYPE_set\*(C'\fR (except for \f(CW\*(C`ev::embed\*(C'\fR watchers>), |
|
|
4282 | with the same arguments. Either this method or a suitable start method |
3279 | called at least once. Unlike the C counterpart, an active watcher gets |
4283 | must be called at least once. Unlike the C counterpart, an active watcher |
3280 | automatically stopped and restarted when reconfiguring it with this |
4284 | gets automatically stopped and restarted when reconfiguring it with this |
3281 | method. |
4285 | method. |
|
|
4286 | .Sp |
|
|
4287 | For \f(CW\*(C`ev::embed\*(C'\fR watchers this method is called \f(CW\*(C`set_embed\*(C'\fR, to avoid |
|
|
4288 | clashing with the \f(CW\*(C`set (loop)\*(C'\fR method. |
3282 | .IP "w\->start ()" 4 |
4289 | .IP "w\->start ()" 4 |
3283 | .IX Item "w->start ()" |
4290 | .IX Item "w->start ()" |
3284 | Starts the watcher. Note that there is no \f(CW\*(C`loop\*(C'\fR argument, as the |
4291 | Starts the watcher. Note that there is no \f(CW\*(C`loop\*(C'\fR argument, as the |
3285 | constructor already stores the event loop. |
4292 | constructor already stores the event loop. |
|
|
4293 | .IP "w\->start ([arguments])" 4 |
|
|
4294 | .IX Item "w->start ([arguments])" |
|
|
4295 | Instead of calling \f(CW\*(C`set\*(C'\fR and \f(CW\*(C`start\*(C'\fR methods separately, it is often |
|
|
4296 | convenient to wrap them in one call. Uses the same type of arguments as |
|
|
4297 | the configure \f(CW\*(C`set\*(C'\fR method of the watcher. |
3286 | .IP "w\->stop ()" 4 |
4298 | .IP "w\->stop ()" 4 |
3287 | .IX Item "w->stop ()" |
4299 | .IX Item "w->stop ()" |
3288 | Stops the watcher if it is active. Again, no \f(CW\*(C`loop\*(C'\fR argument. |
4300 | Stops the watcher if it is active. Again, no \f(CW\*(C`loop\*(C'\fR argument. |
3289 | .ie n .IP "w\->again () (""ev::timer""\fR, \f(CW""ev::periodic"" only)" 4 |
4301 | .ie n .IP "w\->again () (""ev::timer"", ""ev::periodic"" only)" 4 |
3290 | .el .IP "w\->again () (\f(CWev::timer\fR, \f(CWev::periodic\fR only)" 4 |
4302 | .el .IP "w\->again () (\f(CWev::timer\fR, \f(CWev::periodic\fR only)" 4 |
3291 | .IX Item "w->again () (ev::timer, ev::periodic only)" |
4303 | .IX Item "w->again () (ev::timer, ev::periodic only)" |
3292 | For \f(CW\*(C`ev::timer\*(C'\fR and \f(CW\*(C`ev::periodic\*(C'\fR, this invokes the corresponding |
4304 | For \f(CW\*(C`ev::timer\*(C'\fR and \f(CW\*(C`ev::periodic\*(C'\fR, this invokes the corresponding |
3293 | \&\f(CW\*(C`ev_TYPE_again\*(C'\fR function. |
4305 | \&\f(CW\*(C`ev_TYPE_again\*(C'\fR function. |
3294 | .ie n .IP "w\->sweep () (""ev::embed"" only)" 4 |
4306 | .ie n .IP "w\->sweep () (""ev::embed"" only)" 4 |
… | |
… | |
3301 | Invokes \f(CW\*(C`ev_stat_stat\*(C'\fR. |
4313 | Invokes \f(CW\*(C`ev_stat_stat\*(C'\fR. |
3302 | .RE |
4314 | .RE |
3303 | .RS 4 |
4315 | .RS 4 |
3304 | .RE |
4316 | .RE |
3305 | .PP |
4317 | .PP |
3306 | Example: Define a class with an \s-1IO\s0 and idle watcher, start one of them in |
4318 | Example: Define a class with two I/O and idle watchers, start the I/O |
3307 | the constructor. |
4319 | watchers in the constructor. |
3308 | .PP |
4320 | .PP |
3309 | .Vb 4 |
4321 | .Vb 5 |
3310 | \& class myclass |
4322 | \& class myclass |
3311 | \& { |
4323 | \& { |
3312 | \& ev::io io ; void io_cb (ev::io &w, int revents); |
4324 | \& ev::io io ; void io_cb (ev::io &w, int revents); |
|
|
4325 | \& ev::io io2 ; void io2_cb (ev::io &w, int revents); |
3313 | \& ev::idle idle; void idle_cb (ev::idle &w, int revents); |
4326 | \& ev::idle idle; void idle_cb (ev::idle &w, int revents); |
3314 | \& |
4327 | \& |
3315 | \& myclass (int fd) |
4328 | \& myclass (int fd) |
3316 | \& { |
4329 | \& { |
3317 | \& io .set <myclass, &myclass::io_cb > (this); |
4330 | \& io .set <myclass, &myclass::io_cb > (this); |
|
|
4331 | \& io2 .set <myclass, &myclass::io2_cb > (this); |
3318 | \& idle.set <myclass, &myclass::idle_cb> (this); |
4332 | \& idle.set <myclass, &myclass::idle_cb> (this); |
3319 | \& |
4333 | \& |
3320 | \& io.start (fd, ev::READ); |
4334 | \& io.set (fd, ev::WRITE); // configure the watcher |
|
|
4335 | \& io.start (); // start it whenever convenient |
|
|
4336 | \& |
|
|
4337 | \& io2.start (fd, ev::READ); // set + start in one call |
3321 | \& } |
4338 | \& } |
3322 | \& }; |
4339 | \& }; |
3323 | .Ve |
4340 | .Ve |
3324 | .SH "OTHER LANGUAGE BINDINGS" |
4341 | .SH "OTHER LANGUAGE BINDINGS" |
3325 | .IX Header "OTHER LANGUAGE BINDINGS" |
4342 | .IX Header "OTHER LANGUAGE BINDINGS" |
… | |
… | |
3334 | there are additional modules that implement libev-compatible interfaces |
4351 | there are additional modules that implement libev-compatible interfaces |
3335 | to \f(CW\*(C`libadns\*(C'\fR (\f(CW\*(C`EV::ADNS\*(C'\fR, but \f(CW\*(C`AnyEvent::DNS\*(C'\fR is preferred nowadays), |
4352 | to \f(CW\*(C`libadns\*(C'\fR (\f(CW\*(C`EV::ADNS\*(C'\fR, but \f(CW\*(C`AnyEvent::DNS\*(C'\fR is preferred nowadays), |
3336 | \&\f(CW\*(C`Net::SNMP\*(C'\fR (\f(CW\*(C`Net::SNMP::EV\*(C'\fR) and the \f(CW\*(C`libglib\*(C'\fR event core (\f(CW\*(C`Glib::EV\*(C'\fR |
4353 | \&\f(CW\*(C`Net::SNMP\*(C'\fR (\f(CW\*(C`Net::SNMP::EV\*(C'\fR) and the \f(CW\*(C`libglib\*(C'\fR event core (\f(CW\*(C`Glib::EV\*(C'\fR |
3337 | and \f(CW\*(C`EV::Glib\*(C'\fR). |
4354 | and \f(CW\*(C`EV::Glib\*(C'\fR). |
3338 | .Sp |
4355 | .Sp |
3339 | It can be found and installed via \s-1CPAN\s0, its homepage is at |
4356 | It can be found and installed via \s-1CPAN,\s0 its homepage is at |
3340 | <http://software.schmorp.de/pkg/EV>. |
4357 | <http://software.schmorp.de/pkg/EV>. |
3341 | .IP "Python" 4 |
4358 | .IP "Python" 4 |
3342 | .IX Item "Python" |
4359 | .IX Item "Python" |
3343 | Python bindings can be found at <http://code.google.com/p/pyev/>. It |
4360 | Python bindings can be found at <http://code.google.com/p/pyev/>. It |
3344 | seems to be quite complete and well-documented. |
4361 | seems to be quite complete and well-documented. |
… | |
… | |
3356 | A haskell binding to libev is available at |
4373 | A haskell binding to libev is available at |
3357 | <http://hackage.haskell.org/cgi\-bin/hackage\-scripts/package/hlibev>. |
4374 | <http://hackage.haskell.org/cgi\-bin/hackage\-scripts/package/hlibev>. |
3358 | .IP "D" 4 |
4375 | .IP "D" 4 |
3359 | .IX Item "D" |
4376 | .IX Item "D" |
3360 | Leandro Lucarella has written a D language binding (\fIev.d\fR) for libev, to |
4377 | Leandro Lucarella has written a D language binding (\fIev.d\fR) for libev, to |
3361 | be found at <http://proj.llucax.com.ar/wiki/evd>. |
4378 | be found at <http://www.llucax.com.ar/proj/ev.d/index.html>. |
3362 | .IP "Ocaml" 4 |
4379 | .IP "Ocaml" 4 |
3363 | .IX Item "Ocaml" |
4380 | .IX Item "Ocaml" |
3364 | Erkki Seppala has written Ocaml bindings for libev, to be found at |
4381 | Erkki Seppala has written Ocaml bindings for libev, to be found at |
3365 | <http://modeemi.cs.tut.fi/~flux/software/ocaml\-ev/>. |
4382 | <http://modeemi.cs.tut.fi/~flux/software/ocaml\-ev/>. |
|
|
4383 | .IP "Lua" 4 |
|
|
4384 | .IX Item "Lua" |
|
|
4385 | Brian Maher has written a partial interface to libev for lua (at the |
|
|
4386 | time of this writing, only \f(CW\*(C`ev_io\*(C'\fR and \f(CW\*(C`ev_timer\*(C'\fR), to be found at |
|
|
4387 | <http://github.com/brimworks/lua\-ev>. |
|
|
4388 | .IP "Javascript" 4 |
|
|
4389 | .IX Item "Javascript" |
|
|
4390 | Node.js (<http://nodejs.org>) uses libev as the underlying event library. |
|
|
4391 | .IP "Others" 4 |
|
|
4392 | .IX Item "Others" |
|
|
4393 | There are others, and I stopped counting. |
3366 | .SH "MACRO MAGIC" |
4394 | .SH "MACRO MAGIC" |
3367 | .IX Header "MACRO MAGIC" |
4395 | .IX Header "MACRO MAGIC" |
3368 | Libev can be compiled with a variety of options, the most fundamental |
4396 | Libev can be compiled with a variety of options, the most fundamental |
3369 | of which is \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. This option determines whether (most) |
4397 | of which is \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. This option determines whether (most) |
3370 | functions and callbacks have an initial \f(CW\*(C`struct ev_loop *\*(C'\fR argument. |
4398 | functions and callbacks have an initial \f(CW\*(C`struct ev_loop *\*(C'\fR argument. |
3371 | .PP |
4399 | .PP |
3372 | To make it easier to write programs that cope with either variant, the |
4400 | To make it easier to write programs that cope with either variant, the |
3373 | following macros are defined: |
4401 | following macros are defined: |
3374 | .ie n .IP """EV_A""\fR, \f(CW""EV_A_""" 4 |
4402 | .ie n .IP """EV_A"", ""EV_A_""" 4 |
3375 | .el .IP "\f(CWEV_A\fR, \f(CWEV_A_\fR" 4 |
4403 | .el .IP "\f(CWEV_A\fR, \f(CWEV_A_\fR" 4 |
3376 | .IX Item "EV_A, EV_A_" |
4404 | .IX Item "EV_A, EV_A_" |
3377 | This provides the loop \fIargument\fR for functions, if one is required (\*(L"ev |
4405 | This provides the loop \fIargument\fR for functions, if one is required (\*(L"ev |
3378 | loop argument\*(R"). The \f(CW\*(C`EV_A\*(C'\fR form is used when this is the sole argument, |
4406 | loop argument\*(R"). The \f(CW\*(C`EV_A\*(C'\fR form is used when this is the sole argument, |
3379 | \&\f(CW\*(C`EV_A_\*(C'\fR is used when other arguments are following. Example: |
4407 | \&\f(CW\*(C`EV_A_\*(C'\fR is used when other arguments are following. Example: |
3380 | .Sp |
4408 | .Sp |
3381 | .Vb 3 |
4409 | .Vb 3 |
3382 | \& ev_unref (EV_A); |
4410 | \& ev_unref (EV_A); |
3383 | \& ev_timer_add (EV_A_ watcher); |
4411 | \& ev_timer_add (EV_A_ watcher); |
3384 | \& ev_loop (EV_A_ 0); |
4412 | \& ev_run (EV_A_ 0); |
3385 | .Ve |
4413 | .Ve |
3386 | .Sp |
4414 | .Sp |
3387 | It assumes the variable \f(CW\*(C`loop\*(C'\fR of type \f(CW\*(C`struct ev_loop *\*(C'\fR is in scope, |
4415 | It assumes the variable \f(CW\*(C`loop\*(C'\fR of type \f(CW\*(C`struct ev_loop *\*(C'\fR is in scope, |
3388 | which is often provided by the following macro. |
4416 | which is often provided by the following macro. |
3389 | .ie n .IP """EV_P""\fR, \f(CW""EV_P_""" 4 |
4417 | .ie n .IP """EV_P"", ""EV_P_""" 4 |
3390 | .el .IP "\f(CWEV_P\fR, \f(CWEV_P_\fR" 4 |
4418 | .el .IP "\f(CWEV_P\fR, \f(CWEV_P_\fR" 4 |
3391 | .IX Item "EV_P, EV_P_" |
4419 | .IX Item "EV_P, EV_P_" |
3392 | This provides the loop \fIparameter\fR for functions, if one is required (\*(L"ev |
4420 | This provides the loop \fIparameter\fR for functions, if one is required (\*(L"ev |
3393 | loop parameter\*(R"). The \f(CW\*(C`EV_P\*(C'\fR form is used when this is the sole parameter, |
4421 | loop parameter\*(R"). The \f(CW\*(C`EV_P\*(C'\fR form is used when this is the sole parameter, |
3394 | \&\f(CW\*(C`EV_P_\*(C'\fR is used when other parameters are following. Example: |
4422 | \&\f(CW\*(C`EV_P_\*(C'\fR is used when other parameters are following. Example: |
… | |
… | |
3401 | \& static void cb (EV_P_ ev_timer *w, int revents) |
4429 | \& static void cb (EV_P_ ev_timer *w, int revents) |
3402 | .Ve |
4430 | .Ve |
3403 | .Sp |
4431 | .Sp |
3404 | It declares a parameter \f(CW\*(C`loop\*(C'\fR of type \f(CW\*(C`struct ev_loop *\*(C'\fR, quite |
4432 | It declares a parameter \f(CW\*(C`loop\*(C'\fR of type \f(CW\*(C`struct ev_loop *\*(C'\fR, quite |
3405 | suitable for use with \f(CW\*(C`EV_A\*(C'\fR. |
4433 | suitable for use with \f(CW\*(C`EV_A\*(C'\fR. |
3406 | .ie n .IP """EV_DEFAULT""\fR, \f(CW""EV_DEFAULT_""" 4 |
4434 | .ie n .IP """EV_DEFAULT"", ""EV_DEFAULT_""" 4 |
3407 | .el .IP "\f(CWEV_DEFAULT\fR, \f(CWEV_DEFAULT_\fR" 4 |
4435 | .el .IP "\f(CWEV_DEFAULT\fR, \f(CWEV_DEFAULT_\fR" 4 |
3408 | .IX Item "EV_DEFAULT, EV_DEFAULT_" |
4436 | .IX Item "EV_DEFAULT, EV_DEFAULT_" |
3409 | Similar to the other two macros, this gives you the value of the default |
4437 | Similar to the other two macros, this gives you the value of the default |
3410 | loop, if multiple loops are supported (\*(L"ev loop default\*(R"). |
4438 | loop, if multiple loops are supported (\*(L"ev loop default\*(R"). The default loop |
|
|
4439 | will be initialised if it isn't already initialised. |
|
|
4440 | .Sp |
|
|
4441 | For non-multiplicity builds, these macros do nothing, so you always have |
|
|
4442 | to initialise the loop somewhere. |
3411 | .ie n .IP """EV_DEFAULT_UC""\fR, \f(CW""EV_DEFAULT_UC_""" 4 |
4443 | .ie n .IP """EV_DEFAULT_UC"", ""EV_DEFAULT_UC_""" 4 |
3412 | .el .IP "\f(CWEV_DEFAULT_UC\fR, \f(CWEV_DEFAULT_UC_\fR" 4 |
4444 | .el .IP "\f(CWEV_DEFAULT_UC\fR, \f(CWEV_DEFAULT_UC_\fR" 4 |
3413 | .IX Item "EV_DEFAULT_UC, EV_DEFAULT_UC_" |
4445 | .IX Item "EV_DEFAULT_UC, EV_DEFAULT_UC_" |
3414 | Usage identical to \f(CW\*(C`EV_DEFAULT\*(C'\fR and \f(CW\*(C`EV_DEFAULT_\*(C'\fR, but requires that the |
4446 | Usage identical to \f(CW\*(C`EV_DEFAULT\*(C'\fR and \f(CW\*(C`EV_DEFAULT_\*(C'\fR, but requires that the |
3415 | default loop has been initialised (\f(CW\*(C`UC\*(C'\fR == unchecked). Their behaviour |
4447 | default loop has been initialised (\f(CW\*(C`UC\*(C'\fR == unchecked). Their behaviour |
3416 | is undefined when the default loop has not been initialised by a previous |
4448 | is undefined when the default loop has not been initialised by a previous |
… | |
… | |
3431 | \& } |
4463 | \& } |
3432 | \& |
4464 | \& |
3433 | \& ev_check check; |
4465 | \& ev_check check; |
3434 | \& ev_check_init (&check, check_cb); |
4466 | \& ev_check_init (&check, check_cb); |
3435 | \& ev_check_start (EV_DEFAULT_ &check); |
4467 | \& ev_check_start (EV_DEFAULT_ &check); |
3436 | \& ev_loop (EV_DEFAULT_ 0); |
4468 | \& ev_run (EV_DEFAULT_ 0); |
3437 | .Ve |
4469 | .Ve |
3438 | .SH "EMBEDDING" |
4470 | .SH "EMBEDDING" |
3439 | .IX Header "EMBEDDING" |
4471 | .IX Header "EMBEDDING" |
3440 | Libev can (and often is) directly embedded into host |
4472 | Libev can (and often is) directly embedded into host |
3441 | applications. Examples of applications that embed it include the Deliantra |
4473 | applications. Examples of applications that embed it include the Deliantra |
… | |
… | |
3444 | .PP |
4476 | .PP |
3445 | The goal is to enable you to just copy the necessary files into your |
4477 | The goal is to enable you to just copy the necessary files into your |
3446 | source directory without having to change even a single line in them, so |
4478 | source directory without having to change even a single line in them, so |
3447 | you can easily upgrade by simply copying (or having a checked-out copy of |
4479 | you can easily upgrade by simply copying (or having a checked-out copy of |
3448 | libev somewhere in your source tree). |
4480 | libev somewhere in your source tree). |
3449 | .Sh "\s-1FILESETS\s0" |
4481 | .SS "\s-1FILESETS\s0" |
3450 | .IX Subsection "FILESETS" |
4482 | .IX Subsection "FILESETS" |
3451 | Depending on what features you need you need to include one or more sets of files |
4483 | Depending on what features you need you need to include one or more sets of files |
3452 | in your application. |
4484 | in your application. |
3453 | .PP |
4485 | .PP |
3454 | \fI\s-1CORE\s0 \s-1EVENT\s0 \s-1LOOP\s0\fR |
4486 | \fI\s-1CORE EVENT LOOP\s0\fR |
3455 | .IX Subsection "CORE EVENT LOOP" |
4487 | .IX Subsection "CORE EVENT LOOP" |
3456 | .PP |
4488 | .PP |
3457 | To include only the libev core (all the \f(CW\*(C`ev_*\*(C'\fR functions), with manual |
4489 | To include only the libev core (all the \f(CW\*(C`ev_*\*(C'\fR functions), with manual |
3458 | configuration (no autoconf): |
4490 | configuration (no autoconf): |
3459 | .PP |
4491 | .PP |
… | |
… | |
3462 | \& #include "ev.c" |
4494 | \& #include "ev.c" |
3463 | .Ve |
4495 | .Ve |
3464 | .PP |
4496 | .PP |
3465 | This will automatically include \fIev.h\fR, too, and should be done in a |
4497 | This will automatically include \fIev.h\fR, too, and should be done in a |
3466 | single C source file only to provide the function implementations. To use |
4498 | single C source file only to provide the function implementations. To use |
3467 | it, do the same for \fIev.h\fR in all files wishing to use this \s-1API\s0 (best |
4499 | it, do the same for \fIev.h\fR in all files wishing to use this \s-1API \s0(best |
3468 | done by writing a wrapper around \fIev.h\fR that you can include instead and |
4500 | done by writing a wrapper around \fIev.h\fR that you can include instead and |
3469 | where you can put other configuration options): |
4501 | where you can put other configuration options): |
3470 | .PP |
4502 | .PP |
3471 | .Vb 2 |
4503 | .Vb 2 |
3472 | \& #define EV_STANDALONE 1 |
4504 | \& #define EV_STANDALONE 1 |
… | |
… | |
3496 | .Ve |
4528 | .Ve |
3497 | .PP |
4529 | .PP |
3498 | \&\fIev.c\fR includes the backend files directly when enabled, so you only need |
4530 | \&\fIev.c\fR includes the backend files directly when enabled, so you only need |
3499 | to compile this single file. |
4531 | to compile this single file. |
3500 | .PP |
4532 | .PP |
3501 | \fI\s-1LIBEVENT\s0 \s-1COMPATIBILITY\s0 \s-1API\s0\fR |
4533 | \fI\s-1LIBEVENT COMPATIBILITY API\s0\fR |
3502 | .IX Subsection "LIBEVENT COMPATIBILITY API" |
4534 | .IX Subsection "LIBEVENT COMPATIBILITY API" |
3503 | .PP |
4535 | .PP |
3504 | To include the libevent compatibility \s-1API\s0, also include: |
4536 | To include the libevent compatibility \s-1API,\s0 also include: |
3505 | .PP |
4537 | .PP |
3506 | .Vb 1 |
4538 | .Vb 1 |
3507 | \& #include "event.c" |
4539 | \& #include "event.c" |
3508 | .Ve |
4540 | .Ve |
3509 | .PP |
4541 | .PP |
… | |
… | |
3511 | .PP |
4543 | .PP |
3512 | .Vb 1 |
4544 | .Vb 1 |
3513 | \& #include "event.h" |
4545 | \& #include "event.h" |
3514 | .Ve |
4546 | .Ve |
3515 | .PP |
4547 | .PP |
3516 | in the files that want to use the libevent \s-1API\s0. This also includes \fIev.h\fR. |
4548 | in the files that want to use the libevent \s-1API.\s0 This also includes \fIev.h\fR. |
3517 | .PP |
4549 | .PP |
3518 | You need the following additional files for this: |
4550 | You need the following additional files for this: |
3519 | .PP |
4551 | .PP |
3520 | .Vb 2 |
4552 | .Vb 2 |
3521 | \& event.h |
4553 | \& event.h |
3522 | \& event.c |
4554 | \& event.c |
3523 | .Ve |
4555 | .Ve |
3524 | .PP |
4556 | .PP |
3525 | \fI\s-1AUTOCONF\s0 \s-1SUPPORT\s0\fR |
4557 | \fI\s-1AUTOCONF SUPPORT\s0\fR |
3526 | .IX Subsection "AUTOCONF SUPPORT" |
4558 | .IX Subsection "AUTOCONF SUPPORT" |
3527 | .PP |
4559 | .PP |
3528 | Instead of using \f(CW\*(C`EV_STANDALONE=1\*(C'\fR and providing your configuration in |
4560 | Instead of using \f(CW\*(C`EV_STANDALONE=1\*(C'\fR and providing your configuration in |
3529 | whatever way you want, you can also \f(CW\*(C`m4_include([libev.m4])\*(C'\fR in your |
4561 | whatever way you want, you can also \f(CW\*(C`m4_include([libev.m4])\*(C'\fR in your |
3530 | \&\fIconfigure.ac\fR and leave \f(CW\*(C`EV_STANDALONE\*(C'\fR undefined. \fIev.c\fR will then |
4562 | \&\fIconfigure.ac\fR and leave \f(CW\*(C`EV_STANDALONE\*(C'\fR undefined. \fIev.c\fR will then |
… | |
… | |
3533 | For this of course you need the m4 file: |
4565 | For this of course you need the m4 file: |
3534 | .PP |
4566 | .PP |
3535 | .Vb 1 |
4567 | .Vb 1 |
3536 | \& libev.m4 |
4568 | \& libev.m4 |
3537 | .Ve |
4569 | .Ve |
3538 | .Sh "\s-1PREPROCESSOR\s0 \s-1SYMBOLS/MACROS\s0" |
4570 | .SS "\s-1PREPROCESSOR SYMBOLS/MACROS\s0" |
3539 | .IX Subsection "PREPROCESSOR SYMBOLS/MACROS" |
4571 | .IX Subsection "PREPROCESSOR SYMBOLS/MACROS" |
3540 | Libev can be configured via a variety of preprocessor symbols you have to |
4572 | Libev can be configured via a variety of preprocessor symbols you have to |
3541 | define before including any of its files. The default in the absence of |
4573 | define before including (or compiling) any of its files. The default in |
3542 | autoconf is documented for every option. |
4574 | the absence of autoconf is documented for every option. |
|
|
4575 | .PP |
|
|
4576 | Symbols marked with \*(L"(h)\*(R" do not change the \s-1ABI,\s0 and can have different |
|
|
4577 | values when compiling libev vs. including \fIev.h\fR, so it is permissible |
|
|
4578 | to redefine them before including \fIev.h\fR without breaking compatibility |
|
|
4579 | to a compiled library. All other symbols change the \s-1ABI,\s0 which means all |
|
|
4580 | users of libev and the libev code itself must be compiled with compatible |
|
|
4581 | settings. |
|
|
4582 | .IP "\s-1EV_COMPAT3 \s0(h)" 4 |
|
|
4583 | .IX Item "EV_COMPAT3 (h)" |
|
|
4584 | Backwards compatibility is a major concern for libev. This is why this |
|
|
4585 | release of libev comes with wrappers for the functions and symbols that |
|
|
4586 | have been renamed between libev version 3 and 4. |
|
|
4587 | .Sp |
|
|
4588 | You can disable these wrappers (to test compatibility with future |
|
|
4589 | versions) by defining \f(CW\*(C`EV_COMPAT3\*(C'\fR to \f(CW0\fR when compiling your |
|
|
4590 | sources. This has the additional advantage that you can drop the \f(CW\*(C`struct\*(C'\fR |
|
|
4591 | from \f(CW\*(C`struct ev_loop\*(C'\fR declarations, as libev will provide an \f(CW\*(C`ev_loop\*(C'\fR |
|
|
4592 | typedef in that case. |
|
|
4593 | .Sp |
|
|
4594 | In some future version, the default for \f(CW\*(C`EV_COMPAT3\*(C'\fR will become \f(CW0\fR, |
|
|
4595 | and in some even more future version the compatibility code will be |
|
|
4596 | removed completely. |
3543 | .IP "\s-1EV_STANDALONE\s0" 4 |
4597 | .IP "\s-1EV_STANDALONE \s0(h)" 4 |
3544 | .IX Item "EV_STANDALONE" |
4598 | .IX Item "EV_STANDALONE (h)" |
3545 | Must always be \f(CW1\fR if you do not use autoconf configuration, which |
4599 | Must always be \f(CW1\fR if you do not use autoconf configuration, which |
3546 | keeps libev from including \fIconfig.h\fR, and it also defines dummy |
4600 | keeps libev from including \fIconfig.h\fR, and it also defines dummy |
3547 | implementations for some libevent functions (such as logging, which is not |
4601 | implementations for some libevent functions (such as logging, which is not |
3548 | supported). It will also not define any of the structs usually found in |
4602 | supported). It will also not define any of the structs usually found in |
3549 | \&\fIevent.h\fR that are not directly supported by the libev core alone. |
4603 | \&\fIevent.h\fR that are not directly supported by the libev core alone. |
3550 | .Sp |
4604 | .Sp |
3551 | In stanbdalone mode, libev will still try to automatically deduce the |
4605 | In standalone mode, libev will still try to automatically deduce the |
3552 | configuration, but has to be more conservative. |
4606 | configuration, but has to be more conservative. |
|
|
4607 | .IP "\s-1EV_USE_FLOOR\s0" 4 |
|
|
4608 | .IX Item "EV_USE_FLOOR" |
|
|
4609 | If defined to be \f(CW1\fR, libev will use the \f(CW\*(C`floor ()\*(C'\fR function for its |
|
|
4610 | periodic reschedule calculations, otherwise libev will fall back on a |
|
|
4611 | portable (slower) implementation. If you enable this, you usually have to |
|
|
4612 | link against libm or something equivalent. Enabling this when the \f(CW\*(C`floor\*(C'\fR |
|
|
4613 | function is not available will fail, so the safe default is to not enable |
|
|
4614 | this. |
3553 | .IP "\s-1EV_USE_MONOTONIC\s0" 4 |
4615 | .IP "\s-1EV_USE_MONOTONIC\s0" 4 |
3554 | .IX Item "EV_USE_MONOTONIC" |
4616 | .IX Item "EV_USE_MONOTONIC" |
3555 | If defined to be \f(CW1\fR, libev will try to detect the availability of the |
4617 | If defined to be \f(CW1\fR, libev will try to detect the availability of the |
3556 | monotonic clock option at both compile time and runtime. Otherwise no |
4618 | monotonic clock option at both compile time and runtime. Otherwise no |
3557 | use of the monotonic clock option will be attempted. If you enable this, |
4619 | use of the monotonic clock option will be attempted. If you enable this, |
… | |
… | |
3612 | wants osf handles on win32 (this is the case when the select to |
4674 | wants osf handles on win32 (this is the case when the select to |
3613 | be used is the winsock select). This means that it will call |
4675 | be used is the winsock select). This means that it will call |
3614 | \&\f(CW\*(C`_get_osfhandle\*(C'\fR on the fd to convert it to an \s-1OS\s0 handle. Otherwise, |
4676 | \&\f(CW\*(C`_get_osfhandle\*(C'\fR on the fd to convert it to an \s-1OS\s0 handle. Otherwise, |
3615 | it is assumed that all these functions actually work on fds, even |
4677 | it is assumed that all these functions actually work on fds, even |
3616 | on win32. Should not be defined on non\-win32 platforms. |
4678 | on win32. Should not be defined on non\-win32 platforms. |
3617 | .IP "\s-1EV_FD_TO_WIN32_HANDLE\s0" 4 |
4679 | .IP "\s-1EV_FD_TO_WIN32_HANDLE\s0(fd)" 4 |
3618 | .IX Item "EV_FD_TO_WIN32_HANDLE" |
4680 | .IX Item "EV_FD_TO_WIN32_HANDLE(fd)" |
3619 | If \f(CW\*(C`EV_SELECT_IS_WINSOCKET\*(C'\fR is enabled, then libev needs a way to map |
4681 | If \f(CW\*(C`EV_SELECT_IS_WINSOCKET\*(C'\fR is enabled, then libev needs a way to map |
3620 | file descriptors to socket handles. When not defining this symbol (the |
4682 | file descriptors to socket handles. When not defining this symbol (the |
3621 | default), then libev will call \f(CW\*(C`_get_osfhandle\*(C'\fR, which is usually |
4683 | default), then libev will call \f(CW\*(C`_get_osfhandle\*(C'\fR, which is usually |
3622 | correct. In some cases, programs use their own file descriptor management, |
4684 | correct. In some cases, programs use their own file descriptor management, |
3623 | in which case they can provide this function to map fds to socket handles. |
4685 | in which case they can provide this function to map fds to socket handles. |
|
|
4686 | .IP "\s-1EV_WIN32_HANDLE_TO_FD\s0(handle)" 4 |
|
|
4687 | .IX Item "EV_WIN32_HANDLE_TO_FD(handle)" |
|
|
4688 | If \f(CW\*(C`EV_SELECT_IS_WINSOCKET\*(C'\fR then libev maps handles to file descriptors |
|
|
4689 | using the standard \f(CW\*(C`_open_osfhandle\*(C'\fR function. For programs implementing |
|
|
4690 | their own fd to handle mapping, overwriting this function makes it easier |
|
|
4691 | to do so. This can be done by defining this macro to an appropriate value. |
|
|
4692 | .IP "\s-1EV_WIN32_CLOSE_FD\s0(fd)" 4 |
|
|
4693 | .IX Item "EV_WIN32_CLOSE_FD(fd)" |
|
|
4694 | If programs implement their own fd to handle mapping on win32, then this |
|
|
4695 | macro can be used to override the \f(CW\*(C`close\*(C'\fR function, useful to unregister |
|
|
4696 | file descriptors again. Note that the replacement function has to close |
|
|
4697 | the underlying \s-1OS\s0 handle. |
|
|
4698 | .IP "\s-1EV_USE_WSASOCKET\s0" 4 |
|
|
4699 | .IX Item "EV_USE_WSASOCKET" |
|
|
4700 | If defined to be \f(CW1\fR, libev will use \f(CW\*(C`WSASocket\*(C'\fR to create its internal |
|
|
4701 | communication socket, which works better in some environments. Otherwise, |
|
|
4702 | the normal \f(CW\*(C`socket\*(C'\fR function will be used, which works better in other |
|
|
4703 | environments. |
3624 | .IP "\s-1EV_USE_POLL\s0" 4 |
4704 | .IP "\s-1EV_USE_POLL\s0" 4 |
3625 | .IX Item "EV_USE_POLL" |
4705 | .IX Item "EV_USE_POLL" |
3626 | If defined to be \f(CW1\fR, libev will compile in support for the \f(CW\*(C`poll\*(C'\fR(2) |
4706 | If defined to be \f(CW1\fR, libev will compile in support for the \f(CW\*(C`poll\*(C'\fR(2) |
3627 | backend. Otherwise it will be enabled on non\-win32 platforms. It |
4707 | backend. Otherwise it will be enabled on non\-win32 platforms. It |
3628 | takes precedence over select. |
4708 | takes precedence over select. |
… | |
… | |
3657 | .IX Item "EV_USE_INOTIFY" |
4737 | .IX Item "EV_USE_INOTIFY" |
3658 | If defined to be \f(CW1\fR, libev will compile in support for the Linux inotify |
4738 | If defined to be \f(CW1\fR, libev will compile in support for the Linux inotify |
3659 | interface to speed up \f(CW\*(C`ev_stat\*(C'\fR watchers. Its actual availability will |
4739 | interface to speed up \f(CW\*(C`ev_stat\*(C'\fR watchers. Its actual availability will |
3660 | be detected at runtime. If undefined, it will be enabled if the headers |
4740 | be detected at runtime. If undefined, it will be enabled if the headers |
3661 | indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled. |
4741 | indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled. |
|
|
4742 | .IP "\s-1EV_NO_SMP\s0" 4 |
|
|
4743 | .IX Item "EV_NO_SMP" |
|
|
4744 | If defined to be \f(CW1\fR, libev will assume that memory is always coherent |
|
|
4745 | between threads, that is, threads can be used, but threads never run on |
|
|
4746 | different cpus (or different cpu cores). This reduces dependencies |
|
|
4747 | and makes libev faster. |
|
|
4748 | .IP "\s-1EV_NO_THREADS\s0" 4 |
|
|
4749 | .IX Item "EV_NO_THREADS" |
|
|
4750 | If defined to be \f(CW1\fR, libev will assume that it will never be called from |
|
|
4751 | different threads (that includes signal handlers), which is a stronger |
|
|
4752 | assumption than \f(CW\*(C`EV_NO_SMP\*(C'\fR, above. This reduces dependencies and makes |
|
|
4753 | libev faster. |
3662 | .IP "\s-1EV_ATOMIC_T\s0" 4 |
4754 | .IP "\s-1EV_ATOMIC_T\s0" 4 |
3663 | .IX Item "EV_ATOMIC_T" |
4755 | .IX Item "EV_ATOMIC_T" |
3664 | Libev requires an integer type (suitable for storing \f(CW0\fR or \f(CW1\fR) whose |
4756 | Libev requires an integer type (suitable for storing \f(CW0\fR or \f(CW1\fR) whose |
3665 | access is atomic with respect to other threads or signal contexts. No such |
4757 | access is atomic with respect to other threads or signal contexts. No |
3666 | type is easily found in the C language, so you can provide your own type |
4758 | such type is easily found in the C language, so you can provide your own |
3667 | that you know is safe for your purposes. It is used both for signal handler \*(L"locking\*(R" |
4759 | type that you know is safe for your purposes. It is used both for signal |
3668 | as well as for signal and thread safety in \f(CW\*(C`ev_async\*(C'\fR watchers. |
4760 | handler \*(L"locking\*(R" as well as for signal and thread safety in \f(CW\*(C`ev_async\*(C'\fR |
|
|
4761 | watchers. |
3669 | .Sp |
4762 | .Sp |
3670 | In the absence of this define, libev will use \f(CW\*(C`sig_atomic_t volatile\*(C'\fR |
4763 | In the absence of this define, libev will use \f(CW\*(C`sig_atomic_t volatile\*(C'\fR |
3671 | (from \fIsignal.h\fR), which is usually good enough on most platforms. |
4764 | (from \fIsignal.h\fR), which is usually good enough on most platforms. |
3672 | .IP "\s-1EV_H\s0" 4 |
4765 | .IP "\s-1EV_H \s0(h)" 4 |
3673 | .IX Item "EV_H" |
4766 | .IX Item "EV_H (h)" |
3674 | The name of the \fIev.h\fR header file used to include it. The default if |
4767 | The name of the \fIev.h\fR header file used to include it. The default if |
3675 | undefined is \f(CW"ev.h"\fR in \fIevent.h\fR, \fIev.c\fR and \fIev++.h\fR. This can be |
4768 | undefined is \f(CW"ev.h"\fR in \fIevent.h\fR, \fIev.c\fR and \fIev++.h\fR. This can be |
3676 | used to virtually rename the \fIev.h\fR header file in case of conflicts. |
4769 | used to virtually rename the \fIev.h\fR header file in case of conflicts. |
3677 | .IP "\s-1EV_CONFIG_H\s0" 4 |
4770 | .IP "\s-1EV_CONFIG_H \s0(h)" 4 |
3678 | .IX Item "EV_CONFIG_H" |
4771 | .IX Item "EV_CONFIG_H (h)" |
3679 | If \f(CW\*(C`EV_STANDALONE\*(C'\fR isn't \f(CW1\fR, this variable can be used to override |
4772 | If \f(CW\*(C`EV_STANDALONE\*(C'\fR isn't \f(CW1\fR, this variable can be used to override |
3680 | \&\fIev.c\fR's idea of where to find the \fIconfig.h\fR file, similarly to |
4773 | \&\fIev.c\fR's idea of where to find the \fIconfig.h\fR file, similarly to |
3681 | \&\f(CW\*(C`EV_H\*(C'\fR, above. |
4774 | \&\f(CW\*(C`EV_H\*(C'\fR, above. |
3682 | .IP "\s-1EV_EVENT_H\s0" 4 |
4775 | .IP "\s-1EV_EVENT_H \s0(h)" 4 |
3683 | .IX Item "EV_EVENT_H" |
4776 | .IX Item "EV_EVENT_H (h)" |
3684 | Similarly to \f(CW\*(C`EV_H\*(C'\fR, this macro can be used to override \fIevent.c\fR's idea |
4777 | Similarly to \f(CW\*(C`EV_H\*(C'\fR, this macro can be used to override \fIevent.c\fR's idea |
3685 | of how the \fIevent.h\fR header can be found, the default is \f(CW"event.h"\fR. |
4778 | of how the \fIevent.h\fR header can be found, the default is \f(CW"event.h"\fR. |
3686 | .IP "\s-1EV_PROTOTYPES\s0" 4 |
4779 | .IP "\s-1EV_PROTOTYPES \s0(h)" 4 |
3687 | .IX Item "EV_PROTOTYPES" |
4780 | .IX Item "EV_PROTOTYPES (h)" |
3688 | If defined to be \f(CW0\fR, then \fIev.h\fR will not define any function |
4781 | If defined to be \f(CW0\fR, then \fIev.h\fR will not define any function |
3689 | prototypes, but still define all the structs and other symbols. This is |
4782 | prototypes, but still define all the structs and other symbols. This is |
3690 | occasionally useful if you want to provide your own wrapper functions |
4783 | occasionally useful if you want to provide your own wrapper functions |
3691 | around libev functions. |
4784 | around libev functions. |
3692 | .IP "\s-1EV_MULTIPLICITY\s0" 4 |
4785 | .IP "\s-1EV_MULTIPLICITY\s0" 4 |
… | |
… | |
3694 | If undefined or defined to \f(CW1\fR, then all event-loop-specific functions |
4787 | If undefined or defined to \f(CW1\fR, then all event-loop-specific functions |
3695 | will have the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument, and you can create |
4788 | will have the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument, and you can create |
3696 | additional independent event loops. Otherwise there will be no support |
4789 | additional independent event loops. Otherwise there will be no support |
3697 | for multiple event loops and there is no first event loop pointer |
4790 | for multiple event loops and there is no first event loop pointer |
3698 | argument. Instead, all functions act on the single default loop. |
4791 | argument. Instead, all functions act on the single default loop. |
|
|
4792 | .Sp |
|
|
4793 | Note that \f(CW\*(C`EV_DEFAULT\*(C'\fR and \f(CW\*(C`EV_DEFAULT_\*(C'\fR will no longer provide a |
|
|
4794 | default loop when multiplicity is switched off \- you always have to |
|
|
4795 | initialise the loop manually in this case. |
3699 | .IP "\s-1EV_MINPRI\s0" 4 |
4796 | .IP "\s-1EV_MINPRI\s0" 4 |
3700 | .IX Item "EV_MINPRI" |
4797 | .IX Item "EV_MINPRI" |
3701 | .PD 0 |
4798 | .PD 0 |
3702 | .IP "\s-1EV_MAXPRI\s0" 4 |
4799 | .IP "\s-1EV_MAXPRI\s0" 4 |
3703 | .IX Item "EV_MAXPRI" |
4800 | .IX Item "EV_MAXPRI" |
… | |
… | |
3711 | all the priorities, so having many of them (hundreds) uses a lot of space |
4808 | all the priorities, so having many of them (hundreds) uses a lot of space |
3712 | and time, so using the defaults of five priorities (\-2 .. +2) is usually |
4809 | and time, so using the defaults of five priorities (\-2 .. +2) is usually |
3713 | fine. |
4810 | fine. |
3714 | .Sp |
4811 | .Sp |
3715 | If your embedding application does not need any priorities, defining these |
4812 | If your embedding application does not need any priorities, defining these |
3716 | both to \f(CW0\fR will save some memory and \s-1CPU\s0. |
4813 | both to \f(CW0\fR will save some memory and \s-1CPU.\s0 |
3717 | .IP "\s-1EV_PERIODIC_ENABLE\s0" 4 |
4814 | .IP "\s-1EV_PERIODIC_ENABLE, EV_IDLE_ENABLE, EV_EMBED_ENABLE, EV_STAT_ENABLE, EV_PREPARE_ENABLE, EV_CHECK_ENABLE, EV_FORK_ENABLE, EV_SIGNAL_ENABLE, EV_ASYNC_ENABLE, EV_CHILD_ENABLE.\s0" 4 |
3718 | .IX Item "EV_PERIODIC_ENABLE" |
4815 | .IX Item "EV_PERIODIC_ENABLE, EV_IDLE_ENABLE, EV_EMBED_ENABLE, EV_STAT_ENABLE, EV_PREPARE_ENABLE, EV_CHECK_ENABLE, EV_FORK_ENABLE, EV_SIGNAL_ENABLE, EV_ASYNC_ENABLE, EV_CHILD_ENABLE." |
3719 | If undefined or defined to be \f(CW1\fR, then periodic timers are supported. If |
4816 | If undefined or defined to be \f(CW1\fR (and the platform supports it), then |
3720 | defined to be \f(CW0\fR, then they are not. Disabling them saves a few kB of |
4817 | the respective watcher type is supported. If defined to be \f(CW0\fR, then it |
3721 | code. |
4818 | is not. Disabling watcher types mainly saves code size. |
3722 | .IP "\s-1EV_IDLE_ENABLE\s0" 4 |
|
|
3723 | .IX Item "EV_IDLE_ENABLE" |
|
|
3724 | If undefined or defined to be \f(CW1\fR, then idle watchers are supported. If |
|
|
3725 | defined to be \f(CW0\fR, then they are not. Disabling them saves a few kB of |
|
|
3726 | code. |
|
|
3727 | .IP "\s-1EV_EMBED_ENABLE\s0" 4 |
|
|
3728 | .IX Item "EV_EMBED_ENABLE" |
|
|
3729 | If undefined or defined to be \f(CW1\fR, then embed watchers are supported. If |
|
|
3730 | defined to be \f(CW0\fR, then they are not. Embed watchers rely on most other |
|
|
3731 | watcher types, which therefore must not be disabled. |
|
|
3732 | .IP "\s-1EV_STAT_ENABLE\s0" 4 |
4819 | .IP "\s-1EV_FEATURES\s0" 4 |
3733 | .IX Item "EV_STAT_ENABLE" |
4820 | .IX Item "EV_FEATURES" |
3734 | If undefined or defined to be \f(CW1\fR, then stat watchers are supported. If |
|
|
3735 | defined to be \f(CW0\fR, then they are not. |
|
|
3736 | .IP "\s-1EV_FORK_ENABLE\s0" 4 |
|
|
3737 | .IX Item "EV_FORK_ENABLE" |
|
|
3738 | If undefined or defined to be \f(CW1\fR, then fork watchers are supported. If |
|
|
3739 | defined to be \f(CW0\fR, then they are not. |
|
|
3740 | .IP "\s-1EV_ASYNC_ENABLE\s0" 4 |
|
|
3741 | .IX Item "EV_ASYNC_ENABLE" |
|
|
3742 | If undefined or defined to be \f(CW1\fR, then async watchers are supported. If |
|
|
3743 | defined to be \f(CW0\fR, then they are not. |
|
|
3744 | .IP "\s-1EV_MINIMAL\s0" 4 |
|
|
3745 | .IX Item "EV_MINIMAL" |
|
|
3746 | If you need to shave off some kilobytes of code at the expense of some |
4821 | If you need to shave off some kilobytes of code at the expense of some |
3747 | speed, define this symbol to \f(CW1\fR. Currently this is used to override some |
4822 | speed (but with the full \s-1API\s0), you can define this symbol to request |
3748 | inlining decisions, saves roughly 30% code size on amd64. It also selects a |
4823 | certain subsets of functionality. The default is to enable all features |
3749 | much smaller 2\-heap for timer management over the default 4\-heap. |
4824 | that can be enabled on the platform. |
|
|
4825 | .Sp |
|
|
4826 | A typical way to use this symbol is to define it to \f(CW0\fR (or to a bitset |
|
|
4827 | with some broad features you want) and then selectively re-enable |
|
|
4828 | additional parts you want, for example if you want everything minimal, |
|
|
4829 | but multiple event loop support, async and child watchers and the poll |
|
|
4830 | backend, use this: |
|
|
4831 | .Sp |
|
|
4832 | .Vb 5 |
|
|
4833 | \& #define EV_FEATURES 0 |
|
|
4834 | \& #define EV_MULTIPLICITY 1 |
|
|
4835 | \& #define EV_USE_POLL 1 |
|
|
4836 | \& #define EV_CHILD_ENABLE 1 |
|
|
4837 | \& #define EV_ASYNC_ENABLE 1 |
|
|
4838 | .Ve |
|
|
4839 | .Sp |
|
|
4840 | The actual value is a bitset, it can be a combination of the following |
|
|
4841 | values (by default, all of these are enabled): |
|
|
4842 | .RS 4 |
|
|
4843 | .ie n .IP "1 \- faster/larger code" 4 |
|
|
4844 | .el .IP "\f(CW1\fR \- faster/larger code" 4 |
|
|
4845 | .IX Item "1 - faster/larger code" |
|
|
4846 | Use larger code to speed up some operations. |
|
|
4847 | .Sp |
|
|
4848 | Currently this is used to override some inlining decisions (enlarging the |
|
|
4849 | code size by roughly 30% on amd64). |
|
|
4850 | .Sp |
|
|
4851 | When optimising for size, use of compiler flags such as \f(CW\*(C`\-Os\*(C'\fR with |
|
|
4852 | gcc is recommended, as well as \f(CW\*(C`\-DNDEBUG\*(C'\fR, as libev contains a number of |
|
|
4853 | assertions. |
|
|
4854 | .Sp |
|
|
4855 | The default is off when \f(CW\*(C`_\|_OPTIMIZE_SIZE_\|_\*(C'\fR is defined by your compiler |
|
|
4856 | (e.g. gcc with \f(CW\*(C`\-Os\*(C'\fR). |
|
|
4857 | .ie n .IP "2 \- faster/larger data structures" 4 |
|
|
4858 | .el .IP "\f(CW2\fR \- faster/larger data structures" 4 |
|
|
4859 | .IX Item "2 - faster/larger data structures" |
|
|
4860 | Replaces the small 2\-heap for timer management by a faster 4\-heap, larger |
|
|
4861 | hash table sizes and so on. This will usually further increase code size |
|
|
4862 | and can additionally have an effect on the size of data structures at |
|
|
4863 | runtime. |
|
|
4864 | .Sp |
|
|
4865 | The default is off when \f(CW\*(C`_\|_OPTIMIZE_SIZE_\|_\*(C'\fR is defined by your compiler |
|
|
4866 | (e.g. gcc with \f(CW\*(C`\-Os\*(C'\fR). |
|
|
4867 | .ie n .IP "4 \- full \s-1API\s0 configuration" 4 |
|
|
4868 | .el .IP "\f(CW4\fR \- full \s-1API\s0 configuration" 4 |
|
|
4869 | .IX Item "4 - full API configuration" |
|
|
4870 | This enables priorities (sets \f(CW\*(C`EV_MAXPRI\*(C'\fR=2 and \f(CW\*(C`EV_MINPRI\*(C'\fR=\-2), and |
|
|
4871 | enables multiplicity (\f(CW\*(C`EV_MULTIPLICITY\*(C'\fR=1). |
|
|
4872 | .ie n .IP "8 \- full \s-1API\s0" 4 |
|
|
4873 | .el .IP "\f(CW8\fR \- full \s-1API\s0" 4 |
|
|
4874 | .IX Item "8 - full API" |
|
|
4875 | This enables a lot of the \*(L"lesser used\*(R" \s-1API\s0 functions. See \f(CW\*(C`ev.h\*(C'\fR for |
|
|
4876 | details on which parts of the \s-1API\s0 are still available without this |
|
|
4877 | feature, and do not complain if this subset changes over time. |
|
|
4878 | .ie n .IP "16 \- enable all optional watcher types" 4 |
|
|
4879 | .el .IP "\f(CW16\fR \- enable all optional watcher types" 4 |
|
|
4880 | .IX Item "16 - enable all optional watcher types" |
|
|
4881 | Enables all optional watcher types. If you want to selectively enable |
|
|
4882 | only some watcher types other than I/O and timers (e.g. prepare, |
|
|
4883 | embed, async, child...) you can enable them manually by defining |
|
|
4884 | \&\f(CW\*(C`EV_watchertype_ENABLE\*(C'\fR to \f(CW1\fR instead. |
|
|
4885 | .ie n .IP "32 \- enable all backends" 4 |
|
|
4886 | .el .IP "\f(CW32\fR \- enable all backends" 4 |
|
|
4887 | .IX Item "32 - enable all backends" |
|
|
4888 | This enables all backends \- without this feature, you need to enable at |
|
|
4889 | least one backend manually (\f(CW\*(C`EV_USE_SELECT\*(C'\fR is a good choice). |
|
|
4890 | .ie n .IP "64 \- enable OS-specific ""helper"" APIs" 4 |
|
|
4891 | .el .IP "\f(CW64\fR \- enable OS-specific ``helper'' APIs" 4 |
|
|
4892 | .IX Item "64 - enable OS-specific helper APIs" |
|
|
4893 | Enable inotify, eventfd, signalfd and similar OS-specific helper APIs by |
|
|
4894 | default. |
|
|
4895 | .RE |
|
|
4896 | .RS 4 |
|
|
4897 | .Sp |
|
|
4898 | Compiling with \f(CW\*(C`gcc \-Os \-DEV_STANDALONE \-DEV_USE_EPOLL=1 \-DEV_FEATURES=0\*(C'\fR |
|
|
4899 | reduces the compiled size of libev from 24.7Kb code/2.8Kb data to 6.5Kb |
|
|
4900 | code/0.3Kb data on my GNU/Linux amd64 system, while still giving you I/O |
|
|
4901 | watchers, timers and monotonic clock support. |
|
|
4902 | .Sp |
|
|
4903 | With an intelligent-enough linker (gcc+binutils are intelligent enough |
|
|
4904 | when you use \f(CW\*(C`\-Wl,\-\-gc\-sections \-ffunction\-sections\*(C'\fR) functions unused by |
|
|
4905 | your program might be left out as well \- a binary starting a timer and an |
|
|
4906 | I/O watcher then might come out at only 5Kb. |
|
|
4907 | .RE |
|
|
4908 | .IP "\s-1EV_API_STATIC\s0" 4 |
|
|
4909 | .IX Item "EV_API_STATIC" |
|
|
4910 | If this symbol is defined (by default it is not), then all identifiers |
|
|
4911 | will have static linkage. This means that libev will not export any |
|
|
4912 | identifiers, and you cannot link against libev anymore. This can be useful |
|
|
4913 | when you embed libev, only want to use libev functions in a single file, |
|
|
4914 | and do not want its identifiers to be visible. |
|
|
4915 | .Sp |
|
|
4916 | To use this, define \f(CW\*(C`EV_API_STATIC\*(C'\fR and include \fIev.c\fR in the file that |
|
|
4917 | wants to use libev. |
|
|
4918 | .Sp |
|
|
4919 | This option only works when libev is compiled with a C compiler, as \*(C+ |
|
|
4920 | doesn't support the required declaration syntax. |
|
|
4921 | .IP "\s-1EV_AVOID_STDIO\s0" 4 |
|
|
4922 | .IX Item "EV_AVOID_STDIO" |
|
|
4923 | If this is set to \f(CW1\fR at compiletime, then libev will avoid using stdio |
|
|
4924 | functions (printf, scanf, perror etc.). This will increase the code size |
|
|
4925 | somewhat, but if your program doesn't otherwise depend on stdio and your |
|
|
4926 | libc allows it, this avoids linking in the stdio library which is quite |
|
|
4927 | big. |
|
|
4928 | .Sp |
|
|
4929 | Note that error messages might become less precise when this option is |
|
|
4930 | enabled. |
|
|
4931 | .IP "\s-1EV_NSIG\s0" 4 |
|
|
4932 | .IX Item "EV_NSIG" |
|
|
4933 | The highest supported signal number, +1 (or, the number of |
|
|
4934 | signals): Normally, libev tries to deduce the maximum number of signals |
|
|
4935 | automatically, but sometimes this fails, in which case it can be |
|
|
4936 | specified. Also, using a lower number than detected (\f(CW32\fR should be |
|
|
4937 | good for about any system in existence) can save some memory, as libev |
|
|
4938 | statically allocates some 12\-24 bytes per signal number. |
3750 | .IP "\s-1EV_PID_HASHSIZE\s0" 4 |
4939 | .IP "\s-1EV_PID_HASHSIZE\s0" 4 |
3751 | .IX Item "EV_PID_HASHSIZE" |
4940 | .IX Item "EV_PID_HASHSIZE" |
3752 | \&\f(CW\*(C`ev_child\*(C'\fR watchers use a small hash table to distribute workload by |
4941 | \&\f(CW\*(C`ev_child\*(C'\fR watchers use a small hash table to distribute workload by |
3753 | pid. The default size is \f(CW16\fR (or \f(CW1\fR with \f(CW\*(C`EV_MINIMAL\*(C'\fR), usually more |
4942 | pid. The default size is \f(CW16\fR (or \f(CW1\fR with \f(CW\*(C`EV_FEATURES\*(C'\fR disabled), |
3754 | than enough. If you need to manage thousands of children you might want to |
4943 | usually more than enough. If you need to manage thousands of children you |
3755 | increase this value (\fImust\fR be a power of two). |
4944 | might want to increase this value (\fImust\fR be a power of two). |
3756 | .IP "\s-1EV_INOTIFY_HASHSIZE\s0" 4 |
4945 | .IP "\s-1EV_INOTIFY_HASHSIZE\s0" 4 |
3757 | .IX Item "EV_INOTIFY_HASHSIZE" |
4946 | .IX Item "EV_INOTIFY_HASHSIZE" |
3758 | \&\f(CW\*(C`ev_stat\*(C'\fR watchers use a small hash table to distribute workload by |
4947 | \&\f(CW\*(C`ev_stat\*(C'\fR watchers use a small hash table to distribute workload by |
3759 | inotify watch id. The default size is \f(CW16\fR (or \f(CW1\fR with \f(CW\*(C`EV_MINIMAL\*(C'\fR), |
4948 | inotify watch id. The default size is \f(CW16\fR (or \f(CW1\fR with \f(CW\*(C`EV_FEATURES\*(C'\fR |
3760 | usually more than enough. If you need to manage thousands of \f(CW\*(C`ev_stat\*(C'\fR |
4949 | disabled), usually more than enough. If you need to manage thousands of |
3761 | watchers you might want to increase this value (\fImust\fR be a power of |
4950 | \&\f(CW\*(C`ev_stat\*(C'\fR watchers you might want to increase this value (\fImust\fR be a |
3762 | two). |
4951 | power of two). |
3763 | .IP "\s-1EV_USE_4HEAP\s0" 4 |
4952 | .IP "\s-1EV_USE_4HEAP\s0" 4 |
3764 | .IX Item "EV_USE_4HEAP" |
4953 | .IX Item "EV_USE_4HEAP" |
3765 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
4954 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
3766 | timer and periodics heaps, libev uses a 4\-heap when this symbol is defined |
4955 | timer and periodics heaps, libev uses a 4\-heap when this symbol is defined |
3767 | to \f(CW1\fR. The 4\-heap uses more complicated (longer) code but has noticeably |
4956 | to \f(CW1\fR. The 4\-heap uses more complicated (longer) code but has noticeably |
3768 | faster performance with many (thousands) of watchers. |
4957 | faster performance with many (thousands) of watchers. |
3769 | .Sp |
4958 | .Sp |
3770 | The default is \f(CW1\fR unless \f(CW\*(C`EV_MINIMAL\*(C'\fR is set in which case it is \f(CW0\fR |
4959 | The default is \f(CW1\fR, unless \f(CW\*(C`EV_FEATURES\*(C'\fR overrides it, in which case it |
3771 | (disabled). |
4960 | will be \f(CW0\fR. |
3772 | .IP "\s-1EV_HEAP_CACHE_AT\s0" 4 |
4961 | .IP "\s-1EV_HEAP_CACHE_AT\s0" 4 |
3773 | .IX Item "EV_HEAP_CACHE_AT" |
4962 | .IX Item "EV_HEAP_CACHE_AT" |
3774 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
4963 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
3775 | timer and periodics heaps, libev can cache the timestamp (\fIat\fR) within |
4964 | timer and periodics heaps, libev can cache the timestamp (\fIat\fR) within |
3776 | the heap structure (selected by defining \f(CW\*(C`EV_HEAP_CACHE_AT\*(C'\fR to \f(CW1\fR), |
4965 | the heap structure (selected by defining \f(CW\*(C`EV_HEAP_CACHE_AT\*(C'\fR to \f(CW1\fR), |
3777 | which uses 8\-12 bytes more per watcher and a few hundred bytes more code, |
4966 | which uses 8\-12 bytes more per watcher and a few hundred bytes more code, |
3778 | but avoids random read accesses on heap changes. This improves performance |
4967 | but avoids random read accesses on heap changes. This improves performance |
3779 | noticeably with many (hundreds) of watchers. |
4968 | noticeably with many (hundreds) of watchers. |
3780 | .Sp |
4969 | .Sp |
3781 | The default is \f(CW1\fR unless \f(CW\*(C`EV_MINIMAL\*(C'\fR is set in which case it is \f(CW0\fR |
4970 | The default is \f(CW1\fR, unless \f(CW\*(C`EV_FEATURES\*(C'\fR overrides it, in which case it |
3782 | (disabled). |
4971 | will be \f(CW0\fR. |
3783 | .IP "\s-1EV_VERIFY\s0" 4 |
4972 | .IP "\s-1EV_VERIFY\s0" 4 |
3784 | .IX Item "EV_VERIFY" |
4973 | .IX Item "EV_VERIFY" |
3785 | Controls how much internal verification (see \f(CW\*(C`ev_loop_verify ()\*(C'\fR) will |
4974 | Controls how much internal verification (see \f(CW\*(C`ev_verify ()\*(C'\fR) will |
3786 | be done: If set to \f(CW0\fR, no internal verification code will be compiled |
4975 | be done: If set to \f(CW0\fR, no internal verification code will be compiled |
3787 | in. If set to \f(CW1\fR, then verification code will be compiled in, but not |
4976 | in. If set to \f(CW1\fR, then verification code will be compiled in, but not |
3788 | called. If set to \f(CW2\fR, then the internal verification code will be |
4977 | called. If set to \f(CW2\fR, then the internal verification code will be |
3789 | called once per loop, which can slow down libev. If set to \f(CW3\fR, then the |
4978 | called once per loop, which can slow down libev. If set to \f(CW3\fR, then the |
3790 | verification code will be called very frequently, which will slow down |
4979 | verification code will be called very frequently, which will slow down |
3791 | libev considerably. |
4980 | libev considerably. |
3792 | .Sp |
4981 | .Sp |
3793 | The default is \f(CW1\fR, unless \f(CW\*(C`EV_MINIMAL\*(C'\fR is set, in which case it will be |
4982 | The default is \f(CW1\fR, unless \f(CW\*(C`EV_FEATURES\*(C'\fR overrides it, in which case it |
3794 | \&\f(CW0\fR. |
4983 | will be \f(CW0\fR. |
3795 | .IP "\s-1EV_COMMON\s0" 4 |
4984 | .IP "\s-1EV_COMMON\s0" 4 |
3796 | .IX Item "EV_COMMON" |
4985 | .IX Item "EV_COMMON" |
3797 | By default, all watchers have a \f(CW\*(C`void *data\*(C'\fR member. By redefining |
4986 | By default, all watchers have a \f(CW\*(C`void *data\*(C'\fR member. By redefining |
3798 | this macro to a something else you can include more and other types of |
4987 | this macro to something else you can include more and other types of |
3799 | members. You have to define it each time you include one of the files, |
4988 | members. You have to define it each time you include one of the files, |
3800 | though, and it must be identical each time. |
4989 | though, and it must be identical each time. |
3801 | .Sp |
4990 | .Sp |
3802 | For example, the perl \s-1EV\s0 module uses something like this: |
4991 | For example, the perl \s-1EV\s0 module uses something like this: |
3803 | .Sp |
4992 | .Sp |
3804 | .Vb 3 |
4993 | .Vb 3 |
3805 | \& #define EV_COMMON \e |
4994 | \& #define EV_COMMON \e |
3806 | \& SV *self; /* contains this struct */ \e |
4995 | \& SV *self; /* contains this struct */ \e |
3807 | \& SV *cb_sv, *fh /* note no trailing ";" */ |
4996 | \& SV *cb_sv, *fh /* note no trailing ";" */ |
3808 | .Ve |
4997 | .Ve |
3809 | .IP "\s-1EV_CB_DECLARE\s0 (type)" 4 |
4998 | .IP "\s-1EV_CB_DECLARE \s0(type)" 4 |
3810 | .IX Item "EV_CB_DECLARE (type)" |
4999 | .IX Item "EV_CB_DECLARE (type)" |
3811 | .PD 0 |
5000 | .PD 0 |
3812 | .IP "\s-1EV_CB_INVOKE\s0 (watcher, revents)" 4 |
5001 | .IP "\s-1EV_CB_INVOKE \s0(watcher, revents)" 4 |
3813 | .IX Item "EV_CB_INVOKE (watcher, revents)" |
5002 | .IX Item "EV_CB_INVOKE (watcher, revents)" |
3814 | .IP "ev_set_cb (ev, cb)" 4 |
5003 | .IP "ev_set_cb (ev, cb)" 4 |
3815 | .IX Item "ev_set_cb (ev, cb)" |
5004 | .IX Item "ev_set_cb (ev, cb)" |
3816 | .PD |
5005 | .PD |
3817 | Can be used to change the callback member declaration in each watcher, |
5006 | Can be used to change the callback member declaration in each watcher, |
3818 | and the way callbacks are invoked and set. Must expand to a struct member |
5007 | and the way callbacks are invoked and set. Must expand to a struct member |
3819 | definition and a statement, respectively. See the \fIev.h\fR header file for |
5008 | definition and a statement, respectively. See the \fIev.h\fR header file for |
3820 | their default definitions. One possible use for overriding these is to |
5009 | their default definitions. One possible use for overriding these is to |
3821 | avoid the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument in all cases, or to use |
5010 | avoid the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument in all cases, or to use |
3822 | method calls instead of plain function calls in \*(C+. |
5011 | method calls instead of plain function calls in \*(C+. |
3823 | .Sh "\s-1EXPORTED\s0 \s-1API\s0 \s-1SYMBOLS\s0" |
5012 | .SS "\s-1EXPORTED API SYMBOLS\s0" |
3824 | .IX Subsection "EXPORTED API SYMBOLS" |
5013 | .IX Subsection "EXPORTED API SYMBOLS" |
3825 | If you need to re-export the \s-1API\s0 (e.g. via a \s-1DLL\s0) and you need a list of |
5014 | If you need to re-export the \s-1API \s0(e.g. via a \s-1DLL\s0) and you need a list of |
3826 | exported symbols, you can use the provided \fISymbol.*\fR files which list |
5015 | exported symbols, you can use the provided \fISymbol.*\fR files which list |
3827 | all public symbols, one per line: |
5016 | all public symbols, one per line: |
3828 | .PP |
5017 | .PP |
3829 | .Vb 2 |
5018 | .Vb 2 |
3830 | \& Symbols.ev for libev proper |
5019 | \& Symbols.ev for libev proper |
… | |
… | |
3848 | \& #define ev_backend myprefix_ev_backend |
5037 | \& #define ev_backend myprefix_ev_backend |
3849 | \& #define ev_check_start myprefix_ev_check_start |
5038 | \& #define ev_check_start myprefix_ev_check_start |
3850 | \& #define ev_check_stop myprefix_ev_check_stop |
5039 | \& #define ev_check_stop myprefix_ev_check_stop |
3851 | \& ... |
5040 | \& ... |
3852 | .Ve |
5041 | .Ve |
3853 | .Sh "\s-1EXAMPLES\s0" |
5042 | .SS "\s-1EXAMPLES\s0" |
3854 | .IX Subsection "EXAMPLES" |
5043 | .IX Subsection "EXAMPLES" |
3855 | For a real-world example of a program the includes libev |
5044 | For a real-world example of a program the includes libev |
3856 | verbatim, you can have a look at the \s-1EV\s0 perl module |
5045 | verbatim, you can have a look at the \s-1EV\s0 perl module |
3857 | (<http://software.schmorp.de/pkg/EV.html>). It has the libev files in |
5046 | (<http://software.schmorp.de/pkg/EV.html>). It has the libev files in |
3858 | the \fIlibev/\fR subdirectory and includes them in the \fI\s-1EV/EVAPI\s0.h\fR (public |
5047 | the \fIlibev/\fR subdirectory and includes them in the \fI\s-1EV/EVAPI\s0.h\fR (public |
… | |
… | |
3861 | file. |
5050 | file. |
3862 | .PP |
5051 | .PP |
3863 | The usage in rxvt-unicode is simpler. It has a \fIev_cpp.h\fR header file |
5052 | The usage in rxvt-unicode is simpler. It has a \fIev_cpp.h\fR header file |
3864 | that everybody includes and which overrides some configure choices: |
5053 | that everybody includes and which overrides some configure choices: |
3865 | .PP |
5054 | .PP |
3866 | .Vb 9 |
5055 | .Vb 8 |
3867 | \& #define EV_MINIMAL 1 |
5056 | \& #define EV_FEATURES 8 |
3868 | \& #define EV_USE_POLL 0 |
5057 | \& #define EV_USE_SELECT 1 |
3869 | \& #define EV_MULTIPLICITY 0 |
|
|
3870 | \& #define EV_PERIODIC_ENABLE 0 |
5058 | \& #define EV_PREPARE_ENABLE 1 |
|
|
5059 | \& #define EV_IDLE_ENABLE 1 |
3871 | \& #define EV_STAT_ENABLE 0 |
5060 | \& #define EV_SIGNAL_ENABLE 1 |
3872 | \& #define EV_FORK_ENABLE 0 |
5061 | \& #define EV_CHILD_ENABLE 1 |
|
|
5062 | \& #define EV_USE_STDEXCEPT 0 |
3873 | \& #define EV_CONFIG_H <config.h> |
5063 | \& #define EV_CONFIG_H <config.h> |
3874 | \& #define EV_MINPRI 0 |
|
|
3875 | \& #define EV_MAXPRI 0 |
|
|
3876 | \& |
5064 | \& |
3877 | \& #include "ev++.h" |
5065 | \& #include "ev++.h" |
3878 | .Ve |
5066 | .Ve |
3879 | .PP |
5067 | .PP |
3880 | And a \fIev_cpp.C\fR implementation file that contains libev proper and is compiled: |
5068 | And a \fIev_cpp.C\fR implementation file that contains libev proper and is compiled: |
3881 | .PP |
5069 | .PP |
3882 | .Vb 2 |
5070 | .Vb 2 |
3883 | \& #include "ev_cpp.h" |
5071 | \& #include "ev_cpp.h" |
3884 | \& #include "ev.c" |
5072 | \& #include "ev.c" |
3885 | .Ve |
5073 | .Ve |
3886 | .SH "INTERACTION WITH OTHER PROGRAMS OR LIBRARIES" |
5074 | .SH "INTERACTION WITH OTHER PROGRAMS, LIBRARIES OR THE ENVIRONMENT" |
3887 | .IX Header "INTERACTION WITH OTHER PROGRAMS OR LIBRARIES" |
5075 | .IX Header "INTERACTION WITH OTHER PROGRAMS, LIBRARIES OR THE ENVIRONMENT" |
3888 | .Sh "\s-1THREADS\s0 \s-1AND\s0 \s-1COROUTINES\s0" |
5076 | .SS "\s-1THREADS AND COROUTINES\s0" |
3889 | .IX Subsection "THREADS AND COROUTINES" |
5077 | .IX Subsection "THREADS AND COROUTINES" |
3890 | \fI\s-1THREADS\s0\fR |
5078 | \fI\s-1THREADS\s0\fR |
3891 | .IX Subsection "THREADS" |
5079 | .IX Subsection "THREADS" |
3892 | .PP |
5080 | .PP |
3893 | All libev functions are reentrant and thread-safe unless explicitly |
5081 | All libev functions are reentrant and thread-safe unless explicitly |
… | |
… | |
3939 | An example use would be to communicate signals or other events that only |
5127 | An example use would be to communicate signals or other events that only |
3940 | work in the default loop by registering the signal watcher with the |
5128 | work in the default loop by registering the signal watcher with the |
3941 | default loop and triggering an \f(CW\*(C`ev_async\*(C'\fR watcher from the default loop |
5129 | default loop and triggering an \f(CW\*(C`ev_async\*(C'\fR watcher from the default loop |
3942 | watcher callback into the event loop interested in the signal. |
5130 | watcher callback into the event loop interested in the signal. |
3943 | .PP |
5131 | .PP |
|
|
5132 | See also \*(L"\s-1THREAD LOCKING EXAMPLE\*(R"\s0. |
|
|
5133 | .PP |
3944 | \fI\s-1COROUTINES\s0\fR |
5134 | \fI\s-1COROUTINES\s0\fR |
3945 | .IX Subsection "COROUTINES" |
5135 | .IX Subsection "COROUTINES" |
3946 | .PP |
5136 | .PP |
3947 | Libev is very accommodating to coroutines (\*(L"cooperative threads\*(R"): |
5137 | Libev is very accommodating to coroutines (\*(L"cooperative threads\*(R"): |
3948 | libev fully supports nesting calls to its functions from different |
5138 | libev fully supports nesting calls to its functions from different |
3949 | coroutines (e.g. you can call \f(CW\*(C`ev_loop\*(C'\fR on the same loop from two |
5139 | coroutines (e.g. you can call \f(CW\*(C`ev_run\*(C'\fR on the same loop from two |
3950 | different coroutines, and switch freely between both coroutines running the |
5140 | different coroutines, and switch freely between both coroutines running |
3951 | loop, as long as you don't confuse yourself). The only exception is that |
5141 | the loop, as long as you don't confuse yourself). The only exception is |
3952 | you must not do this from \f(CW\*(C`ev_periodic\*(C'\fR reschedule callbacks. |
5142 | that you must not do this from \f(CW\*(C`ev_periodic\*(C'\fR reschedule callbacks. |
3953 | .PP |
5143 | .PP |
3954 | Care has been taken to ensure that libev does not keep local state inside |
5144 | Care has been taken to ensure that libev does not keep local state inside |
3955 | \&\f(CW\*(C`ev_loop\*(C'\fR, and other calls do not usually allow for coroutine switches as |
5145 | \&\f(CW\*(C`ev_run\*(C'\fR, and other calls do not usually allow for coroutine switches as |
3956 | they do not call any callbacks. |
5146 | they do not call any callbacks. |
3957 | .Sh "\s-1COMPILER\s0 \s-1WARNINGS\s0" |
5147 | .SS "\s-1COMPILER WARNINGS\s0" |
3958 | .IX Subsection "COMPILER WARNINGS" |
5148 | .IX Subsection "COMPILER WARNINGS" |
3959 | Depending on your compiler and compiler settings, you might get no or a |
5149 | Depending on your compiler and compiler settings, you might get no or a |
3960 | lot of warnings when compiling libev code. Some people are apparently |
5150 | lot of warnings when compiling libev code. Some people are apparently |
3961 | scared by this. |
5151 | scared by this. |
3962 | .PP |
5152 | .PP |
… | |
… | |
3970 | maintainable. |
5160 | maintainable. |
3971 | .PP |
5161 | .PP |
3972 | And of course, some compiler warnings are just plain stupid, or simply |
5162 | And of course, some compiler warnings are just plain stupid, or simply |
3973 | wrong (because they don't actually warn about the condition their message |
5163 | wrong (because they don't actually warn about the condition their message |
3974 | seems to warn about). For example, certain older gcc versions had some |
5164 | seems to warn about). For example, certain older gcc versions had some |
3975 | warnings that resulted an extreme number of false positives. These have |
5165 | warnings that resulted in an extreme number of false positives. These have |
3976 | been fixed, but some people still insist on making code warn-free with |
5166 | been fixed, but some people still insist on making code warn-free with |
3977 | such buggy versions. |
5167 | such buggy versions. |
3978 | .PP |
5168 | .PP |
3979 | While libev is written to generate as few warnings as possible, |
5169 | While libev is written to generate as few warnings as possible, |
3980 | \&\*(L"warn-free\*(R" code is not a goal, and it is recommended not to build libev |
5170 | \&\*(L"warn-free\*(R" code is not a goal, and it is recommended not to build libev |
3981 | with any compiler warnings enabled unless you are prepared to cope with |
5171 | with any compiler warnings enabled unless you are prepared to cope with |
3982 | them (e.g. by ignoring them). Remember that warnings are just that: |
5172 | them (e.g. by ignoring them). Remember that warnings are just that: |
3983 | warnings, not errors, or proof of bugs. |
5173 | warnings, not errors, or proof of bugs. |
3984 | .Sh "\s-1VALGRIND\s0" |
5174 | .SS "\s-1VALGRIND\s0" |
3985 | .IX Subsection "VALGRIND" |
5175 | .IX Subsection "VALGRIND" |
3986 | Valgrind has a special section here because it is a popular tool that is |
5176 | Valgrind has a special section here because it is a popular tool that is |
3987 | highly useful. Unfortunately, valgrind reports are very hard to interpret. |
5177 | highly useful. Unfortunately, valgrind reports are very hard to interpret. |
3988 | .PP |
5178 | .PP |
3989 | If you think you found a bug (memory leak, uninitialised data access etc.) |
5179 | If you think you found a bug (memory leak, uninitialised data access etc.) |
… | |
… | |
4014 | .PP |
5204 | .PP |
4015 | If you need, for some reason, empty reports from valgrind for your project |
5205 | If you need, for some reason, empty reports from valgrind for your project |
4016 | I suggest using suppression lists. |
5206 | I suggest using suppression lists. |
4017 | .SH "PORTABILITY NOTES" |
5207 | .SH "PORTABILITY NOTES" |
4018 | .IX Header "PORTABILITY NOTES" |
5208 | .IX Header "PORTABILITY NOTES" |
4019 | .Sh "\s-1WIN32\s0 \s-1PLATFORM\s0 \s-1LIMITATIONS\s0 \s-1AND\s0 \s-1WORKAROUNDS\s0" |
5209 | .SS "\s-1GNU/LINUX 32 BIT LIMITATIONS\s0" |
|
|
5210 | .IX Subsection "GNU/LINUX 32 BIT LIMITATIONS" |
|
|
5211 | GNU/Linux is the only common platform that supports 64 bit file/large file |
|
|
5212 | interfaces but \fIdisables\fR them by default. |
|
|
5213 | .PP |
|
|
5214 | That means that libev compiled in the default environment doesn't support |
|
|
5215 | files larger than 2GiB or so, which mainly affects \f(CW\*(C`ev_stat\*(C'\fR watchers. |
|
|
5216 | .PP |
|
|
5217 | Unfortunately, many programs try to work around this GNU/Linux issue |
|
|
5218 | by enabling the large file \s-1API,\s0 which makes them incompatible with the |
|
|
5219 | standard libev compiled for their system. |
|
|
5220 | .PP |
|
|
5221 | Likewise, libev cannot enable the large file \s-1API\s0 itself as this would |
|
|
5222 | suddenly make it incompatible to the default compile time environment, |
|
|
5223 | i.e. all programs not using special compile switches. |
|
|
5224 | .SS "\s-1OS/X AND DARWIN BUGS\s0" |
|
|
5225 | .IX Subsection "OS/X AND DARWIN BUGS" |
|
|
5226 | The whole thing is a bug if you ask me \- basically any system interface |
|
|
5227 | you touch is broken, whether it is locales, poll, kqueue or even the |
|
|
5228 | OpenGL drivers. |
|
|
5229 | .PP |
|
|
5230 | \fI\f(CI\*(C`kqueue\*(C'\fI is buggy\fR |
|
|
5231 | .IX Subsection "kqueue is buggy" |
|
|
5232 | .PP |
|
|
5233 | The kqueue syscall is broken in all known versions \- most versions support |
|
|
5234 | only sockets, many support pipes. |
|
|
5235 | .PP |
|
|
5236 | Libev tries to work around this by not using \f(CW\*(C`kqueue\*(C'\fR by default on this |
|
|
5237 | rotten platform, but of course you can still ask for it when creating a |
|
|
5238 | loop \- embedding a socket-only kqueue loop into a select-based one is |
|
|
5239 | probably going to work well. |
|
|
5240 | .PP |
|
|
5241 | \fI\f(CI\*(C`poll\*(C'\fI is buggy\fR |
|
|
5242 | .IX Subsection "poll is buggy" |
|
|
5243 | .PP |
|
|
5244 | Instead of fixing \f(CW\*(C`kqueue\*(C'\fR, Apple replaced their (working) \f(CW\*(C`poll\*(C'\fR |
|
|
5245 | implementation by something calling \f(CW\*(C`kqueue\*(C'\fR internally around the 10.5.6 |
|
|
5246 | release, so now \f(CW\*(C`kqueue\*(C'\fR \fIand\fR \f(CW\*(C`poll\*(C'\fR are broken. |
|
|
5247 | .PP |
|
|
5248 | Libev tries to work around this by not using \f(CW\*(C`poll\*(C'\fR by default on |
|
|
5249 | this rotten platform, but of course you can still ask for it when creating |
|
|
5250 | a loop. |
|
|
5251 | .PP |
|
|
5252 | \fI\f(CI\*(C`select\*(C'\fI is buggy\fR |
|
|
5253 | .IX Subsection "select is buggy" |
|
|
5254 | .PP |
|
|
5255 | All that's left is \f(CW\*(C`select\*(C'\fR, and of course Apple found a way to fuck this |
|
|
5256 | one up as well: On \s-1OS/X, \s0\f(CW\*(C`select\*(C'\fR actively limits the number of file |
|
|
5257 | descriptors you can pass in to 1024 \- your program suddenly crashes when |
|
|
5258 | you use more. |
|
|
5259 | .PP |
|
|
5260 | There is an undocumented \*(L"workaround\*(R" for this \- defining |
|
|
5261 | \&\f(CW\*(C`_DARWIN_UNLIMITED_SELECT\*(C'\fR, which libev tries to use, so select \fIshould\fR |
|
|
5262 | work on \s-1OS/X.\s0 |
|
|
5263 | .SS "\s-1SOLARIS PROBLEMS AND WORKAROUNDS\s0" |
|
|
5264 | .IX Subsection "SOLARIS PROBLEMS AND WORKAROUNDS" |
|
|
5265 | \fI\f(CI\*(C`errno\*(C'\fI reentrancy\fR |
|
|
5266 | .IX Subsection "errno reentrancy" |
|
|
5267 | .PP |
|
|
5268 | The default compile environment on Solaris is unfortunately so |
|
|
5269 | thread-unsafe that you can't even use components/libraries compiled |
|
|
5270 | without \f(CW\*(C`\-D_REENTRANT\*(C'\fR in a threaded program, which, of course, isn't |
|
|
5271 | defined by default. A valid, if stupid, implementation choice. |
|
|
5272 | .PP |
|
|
5273 | If you want to use libev in threaded environments you have to make sure |
|
|
5274 | it's compiled with \f(CW\*(C`_REENTRANT\*(C'\fR defined. |
|
|
5275 | .PP |
|
|
5276 | \fIEvent port backend\fR |
|
|
5277 | .IX Subsection "Event port backend" |
|
|
5278 | .PP |
|
|
5279 | The scalable event interface for Solaris is called \*(L"event |
|
|
5280 | ports\*(R". Unfortunately, this mechanism is very buggy in all major |
|
|
5281 | releases. If you run into high \s-1CPU\s0 usage, your program freezes or you get |
|
|
5282 | a large number of spurious wakeups, make sure you have all the relevant |
|
|
5283 | and latest kernel patches applied. No, I don't know which ones, but there |
|
|
5284 | are multiple ones to apply, and afterwards, event ports actually work |
|
|
5285 | great. |
|
|
5286 | .PP |
|
|
5287 | If you can't get it to work, you can try running the program by setting |
|
|
5288 | the environment variable \f(CW\*(C`LIBEV_FLAGS=3\*(C'\fR to only allow \f(CW\*(C`poll\*(C'\fR and |
|
|
5289 | \&\f(CW\*(C`select\*(C'\fR backends. |
|
|
5290 | .SS "\s-1AIX POLL BUG\s0" |
|
|
5291 | .IX Subsection "AIX POLL BUG" |
|
|
5292 | \&\s-1AIX\s0 unfortunately has a broken \f(CW\*(C`poll.h\*(C'\fR header. Libev works around |
|
|
5293 | this by trying to avoid the poll backend altogether (i.e. it's not even |
|
|
5294 | compiled in), which normally isn't a big problem as \f(CW\*(C`select\*(C'\fR works fine |
|
|
5295 | with large bitsets on \s-1AIX,\s0 and \s-1AIX\s0 is dead anyway. |
|
|
5296 | .SS "\s-1WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS\s0" |
4020 | .IX Subsection "WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS" |
5297 | .IX Subsection "WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS" |
|
|
5298 | \fIGeneral issues\fR |
|
|
5299 | .IX Subsection "General issues" |
|
|
5300 | .PP |
4021 | Win32 doesn't support any of the standards (e.g. \s-1POSIX\s0) that libev |
5301 | Win32 doesn't support any of the standards (e.g. \s-1POSIX\s0) that libev |
4022 | requires, and its I/O model is fundamentally incompatible with the \s-1POSIX\s0 |
5302 | requires, and its I/O model is fundamentally incompatible with the \s-1POSIX\s0 |
4023 | model. Libev still offers limited functionality on this platform in |
5303 | model. Libev still offers limited functionality on this platform in |
4024 | the form of the \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR backend, and only supports socket |
5304 | the form of the \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR backend, and only supports socket |
4025 | descriptors. This only applies when using Win32 natively, not when using |
5305 | descriptors. This only applies when using Win32 natively, not when using |
4026 | e.g. cygwin. |
5306 | e.g. cygwin. Actually, it only applies to the microsofts own compilers, |
|
|
5307 | as every compiler comes with a slightly differently broken/incompatible |
|
|
5308 | environment. |
4027 | .PP |
5309 | .PP |
4028 | Lifting these limitations would basically require the full |
5310 | Lifting these limitations would basically require the full |
4029 | re-implementation of the I/O system. If you are into these kinds of |
5311 | re-implementation of the I/O system. If you are into this kind of thing, |
4030 | things, then note that glib does exactly that for you in a very portable |
5312 | then note that glib does exactly that for you in a very portable way (note |
4031 | way (note also that glib is the slowest event library known to man). |
5313 | also that glib is the slowest event library known to man). |
4032 | .PP |
5314 | .PP |
4033 | There is no supported compilation method available on windows except |
5315 | There is no supported compilation method available on windows except |
4034 | embedding it into other applications. |
5316 | embedding it into other applications. |
4035 | .PP |
5317 | .PP |
4036 | Sensible signal handling is officially unsupported by Microsoft \- libev |
5318 | Sensible signal handling is officially unsupported by Microsoft \- libev |
… | |
… | |
4067 | .PP |
5349 | .PP |
4068 | .Vb 2 |
5350 | .Vb 2 |
4069 | \& #include "evwrap.h" |
5351 | \& #include "evwrap.h" |
4070 | \& #include "ev.c" |
5352 | \& #include "ev.c" |
4071 | .Ve |
5353 | .Ve |
4072 | .IP "The winsocket select function" 4 |
5354 | .PP |
|
|
5355 | \fIThe winsocket \f(CI\*(C`select\*(C'\fI function\fR |
4073 | .IX Item "The winsocket select function" |
5356 | .IX Subsection "The winsocket select function" |
|
|
5357 | .PP |
4074 | The winsocket \f(CW\*(C`select\*(C'\fR function doesn't follow \s-1POSIX\s0 in that it |
5358 | The winsocket \f(CW\*(C`select\*(C'\fR function doesn't follow \s-1POSIX\s0 in that it |
4075 | requires socket \fIhandles\fR and not socket \fIfile descriptors\fR (it is |
5359 | requires socket \fIhandles\fR and not socket \fIfile descriptors\fR (it is |
4076 | also extremely buggy). This makes select very inefficient, and also |
5360 | also extremely buggy). This makes select very inefficient, and also |
4077 | requires a mapping from file descriptors to socket handles (the Microsoft |
5361 | requires a mapping from file descriptors to socket handles (the Microsoft |
4078 | C runtime provides the function \f(CW\*(C`_open_osfhandle\*(C'\fR for this). See the |
5362 | C runtime provides the function \f(CW\*(C`_open_osfhandle\*(C'\fR for this). See the |
4079 | discussion of the \f(CW\*(C`EV_SELECT_USE_FD_SET\*(C'\fR, \f(CW\*(C`EV_SELECT_IS_WINSOCKET\*(C'\fR and |
5363 | discussion of the \f(CW\*(C`EV_SELECT_USE_FD_SET\*(C'\fR, \f(CW\*(C`EV_SELECT_IS_WINSOCKET\*(C'\fR and |
4080 | \&\f(CW\*(C`EV_FD_TO_WIN32_HANDLE\*(C'\fR preprocessor symbols for more info. |
5364 | \&\f(CW\*(C`EV_FD_TO_WIN32_HANDLE\*(C'\fR preprocessor symbols for more info. |
4081 | .Sp |
5365 | .PP |
4082 | The configuration for a \*(L"naked\*(R" win32 using the Microsoft runtime |
5366 | The configuration for a \*(L"naked\*(R" win32 using the Microsoft runtime |
4083 | libraries and raw winsocket select is: |
5367 | libraries and raw winsocket select is: |
4084 | .Sp |
5368 | .PP |
4085 | .Vb 2 |
5369 | .Vb 2 |
4086 | \& #define EV_USE_SELECT 1 |
5370 | \& #define EV_USE_SELECT 1 |
4087 | \& #define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */ |
5371 | \& #define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */ |
4088 | .Ve |
5372 | .Ve |
4089 | .Sp |
5373 | .PP |
4090 | Note that winsockets handling of fd sets is O(n), so you can easily get a |
5374 | Note that winsockets handling of fd sets is O(n), so you can easily get a |
4091 | complexity in the O(nA\*^X) range when using win32. |
5375 | complexity in the O(nX) range when using win32. |
|
|
5376 | .PP |
4092 | .IP "Limited number of file descriptors" 4 |
5377 | \fILimited number of file descriptors\fR |
4093 | .IX Item "Limited number of file descriptors" |
5378 | .IX Subsection "Limited number of file descriptors" |
|
|
5379 | .PP |
4094 | Windows has numerous arbitrary (and low) limits on things. |
5380 | Windows has numerous arbitrary (and low) limits on things. |
4095 | .Sp |
5381 | .PP |
4096 | Early versions of winsocket's select only supported waiting for a maximum |
5382 | Early versions of winsocket's select only supported waiting for a maximum |
4097 | of \f(CW64\fR handles (probably owning to the fact that all windows kernels |
5383 | of \f(CW64\fR handles (probably owning to the fact that all windows kernels |
4098 | can only wait for \f(CW64\fR things at the same time internally; Microsoft |
5384 | can only wait for \f(CW64\fR things at the same time internally; Microsoft |
4099 | recommends spawning a chain of threads and wait for 63 handles and the |
5385 | recommends spawning a chain of threads and wait for 63 handles and the |
4100 | previous thread in each. Sounds great!). |
5386 | previous thread in each. Sounds great!). |
4101 | .Sp |
5387 | .PP |
4102 | Newer versions support more handles, but you need to define \f(CW\*(C`FD_SETSIZE\*(C'\fR |
5388 | Newer versions support more handles, but you need to define \f(CW\*(C`FD_SETSIZE\*(C'\fR |
4103 | to some high number (e.g. \f(CW2048\fR) before compiling the winsocket select |
5389 | to some high number (e.g. \f(CW2048\fR) before compiling the winsocket select |
4104 | call (which might be in libev or elsewhere, for example, perl and many |
5390 | call (which might be in libev or elsewhere, for example, perl and many |
4105 | other interpreters do their own select emulation on windows). |
5391 | other interpreters do their own select emulation on windows). |
4106 | .Sp |
5392 | .PP |
4107 | Another limit is the number of file descriptors in the Microsoft runtime |
5393 | Another limit is the number of file descriptors in the Microsoft runtime |
4108 | libraries, which by default is \f(CW64\fR (there must be a hidden \fI64\fR |
5394 | libraries, which by default is \f(CW64\fR (there must be a hidden \fI64\fR |
4109 | fetish or something like this inside Microsoft). You can increase this |
5395 | fetish or something like this inside Microsoft). You can increase this |
4110 | by calling \f(CW\*(C`_setmaxstdio\*(C'\fR, which can increase this limit to \f(CW2048\fR |
5396 | by calling \f(CW\*(C`_setmaxstdio\*(C'\fR, which can increase this limit to \f(CW2048\fR |
4111 | (another arbitrary limit), but is broken in many versions of the Microsoft |
5397 | (another arbitrary limit), but is broken in many versions of the Microsoft |
4112 | runtime libraries. This might get you to about \f(CW512\fR or \f(CW2048\fR sockets |
5398 | runtime libraries. This might get you to about \f(CW512\fR or \f(CW2048\fR sockets |
4113 | (depending on windows version and/or the phase of the moon). To get more, |
5399 | (depending on windows version and/or the phase of the moon). To get more, |
4114 | you need to wrap all I/O functions and provide your own fd management, but |
5400 | you need to wrap all I/O functions and provide your own fd management, but |
4115 | the cost of calling select (O(nA\*^X)) will likely make this unworkable. |
5401 | the cost of calling select (O(nX)) will likely make this unworkable. |
4116 | .Sh "\s-1PORTABILITY\s0 \s-1REQUIREMENTS\s0" |
5402 | .SS "\s-1PORTABILITY REQUIREMENTS\s0" |
4117 | .IX Subsection "PORTABILITY REQUIREMENTS" |
5403 | .IX Subsection "PORTABILITY REQUIREMENTS" |
4118 | In addition to a working ISO-C implementation and of course the |
5404 | In addition to a working ISO-C implementation and of course the |
4119 | backend-specific APIs, libev relies on a few additional extensions: |
5405 | backend-specific APIs, libev relies on a few additional extensions: |
4120 | .ie n .IP """void (*)(ev_watcher_type *, int revents)""\fR must have compatible calling conventions regardless of \f(CW""ev_watcher_type *""." 4 |
5406 | .ie n .IP """void (*)(ev_watcher_type *, int revents)"" must have compatible calling conventions regardless of ""ev_watcher_type *""." 4 |
4121 | .el .IP "\f(CWvoid (*)(ev_watcher_type *, int revents)\fR must have compatible calling conventions regardless of \f(CWev_watcher_type *\fR." 4 |
5407 | .el .IP "\f(CWvoid (*)(ev_watcher_type *, int revents)\fR must have compatible calling conventions regardless of \f(CWev_watcher_type *\fR." 4 |
4122 | .IX Item "void (*)(ev_watcher_type *, int revents) must have compatible calling conventions regardless of ev_watcher_type *." |
5408 | .IX Item "void (*)(ev_watcher_type *, int revents) must have compatible calling conventions regardless of ev_watcher_type *." |
4123 | Libev assumes not only that all watcher pointers have the same internal |
5409 | Libev assumes not only that all watcher pointers have the same internal |
4124 | structure (guaranteed by \s-1POSIX\s0 but not by \s-1ISO\s0 C for example), but it also |
5410 | structure (guaranteed by \s-1POSIX\s0 but not by \s-1ISO C\s0 for example), but it also |
4125 | assumes that the same (machine) code can be used to call any watcher |
5411 | assumes that the same (machine) code can be used to call any watcher |
4126 | callback: The watcher callbacks have different type signatures, but libev |
5412 | callback: The watcher callbacks have different type signatures, but libev |
4127 | calls them using an \f(CW\*(C`ev_watcher *\*(C'\fR internally. |
5413 | calls them using an \f(CW\*(C`ev_watcher *\*(C'\fR internally. |
|
|
5414 | .IP "pointer accesses must be thread-atomic" 4 |
|
|
5415 | .IX Item "pointer accesses must be thread-atomic" |
|
|
5416 | Accessing a pointer value must be atomic, it must both be readable and |
|
|
5417 | writable in one piece \- this is the case on all current architectures. |
4128 | .ie n .IP """sig_atomic_t volatile"" must be thread-atomic as well" 4 |
5418 | .ie n .IP """sig_atomic_t volatile"" must be thread-atomic as well" 4 |
4129 | .el .IP "\f(CWsig_atomic_t volatile\fR must be thread-atomic as well" 4 |
5419 | .el .IP "\f(CWsig_atomic_t volatile\fR must be thread-atomic as well" 4 |
4130 | .IX Item "sig_atomic_t volatile must be thread-atomic as well" |
5420 | .IX Item "sig_atomic_t volatile must be thread-atomic as well" |
4131 | The type \f(CW\*(C`sig_atomic_t volatile\*(C'\fR (or whatever is defined as |
5421 | The type \f(CW\*(C`sig_atomic_t volatile\*(C'\fR (or whatever is defined as |
4132 | \&\f(CW\*(C`EV_ATOMIC_T\*(C'\fR) must be atomic with respect to accesses from different |
5422 | \&\f(CW\*(C`EV_ATOMIC_T\*(C'\fR) must be atomic with respect to accesses from different |
… | |
… | |
4141 | thread\*(R" or will block signals process-wide, both behaviours would |
5431 | thread\*(R" or will block signals process-wide, both behaviours would |
4142 | be compatible with libev. Interaction between \f(CW\*(C`sigprocmask\*(C'\fR and |
5432 | be compatible with libev. Interaction between \f(CW\*(C`sigprocmask\*(C'\fR and |
4143 | \&\f(CW\*(C`pthread_sigmask\*(C'\fR could complicate things, however. |
5433 | \&\f(CW\*(C`pthread_sigmask\*(C'\fR could complicate things, however. |
4144 | .Sp |
5434 | .Sp |
4145 | The most portable way to handle signals is to block signals in all threads |
5435 | The most portable way to handle signals is to block signals in all threads |
4146 | except the initial one, and run the default loop in the initial thread as |
5436 | except the initial one, and run the signal handling loop in the initial |
4147 | well. |
5437 | thread as well. |
4148 | .ie n .IP """long"" must be large enough for common memory allocation sizes" 4 |
5438 | .ie n .IP """long"" must be large enough for common memory allocation sizes" 4 |
4149 | .el .IP "\f(CWlong\fR must be large enough for common memory allocation sizes" 4 |
5439 | .el .IP "\f(CWlong\fR must be large enough for common memory allocation sizes" 4 |
4150 | .IX Item "long must be large enough for common memory allocation sizes" |
5440 | .IX Item "long must be large enough for common memory allocation sizes" |
4151 | To improve portability and simplify its \s-1API\s0, libev uses \f(CW\*(C`long\*(C'\fR internally |
5441 | To improve portability and simplify its \s-1API,\s0 libev uses \f(CW\*(C`long\*(C'\fR internally |
4152 | instead of \f(CW\*(C`size_t\*(C'\fR when allocating its data structures. On non-POSIX |
5442 | instead of \f(CW\*(C`size_t\*(C'\fR when allocating its data structures. On non-POSIX |
4153 | systems (Microsoft...) this might be unexpectedly low, but is still at |
5443 | systems (Microsoft...) this might be unexpectedly low, but is still at |
4154 | least 31 bits everywhere, which is enough for hundreds of millions of |
5444 | least 31 bits everywhere, which is enough for hundreds of millions of |
4155 | watchers. |
5445 | watchers. |
4156 | .ie n .IP """double"" must hold a time value in seconds with enough accuracy" 4 |
5446 | .ie n .IP """double"" must hold a time value in seconds with enough accuracy" 4 |
4157 | .el .IP "\f(CWdouble\fR must hold a time value in seconds with enough accuracy" 4 |
5447 | .el .IP "\f(CWdouble\fR must hold a time value in seconds with enough accuracy" 4 |
4158 | .IX Item "double must hold a time value in seconds with enough accuracy" |
5448 | .IX Item "double must hold a time value in seconds with enough accuracy" |
4159 | The type \f(CW\*(C`double\*(C'\fR is used to represent timestamps. It is required to |
5449 | The type \f(CW\*(C`double\*(C'\fR is used to represent timestamps. It is required to |
4160 | have at least 51 bits of mantissa (and 9 bits of exponent), which is good |
5450 | have at least 51 bits of mantissa (and 9 bits of exponent), which is |
4161 | enough for at least into the year 4000. This requirement is fulfilled by |
5451 | good enough for at least into the year 4000 with millisecond accuracy |
|
|
5452 | (the design goal for libev). This requirement is overfulfilled by |
4162 | implementations implementing \s-1IEEE\s0 754 (basically all existing ones). |
5453 | implementations using \s-1IEEE 754,\s0 which is basically all existing ones. |
|
|
5454 | .Sp |
|
|
5455 | With \s-1IEEE 754\s0 doubles, you get microsecond accuracy until at least the |
|
|
5456 | year 2255 (and millisecond accuracy till the year 287396 \- by then, libev |
|
|
5457 | is either obsolete or somebody patched it to use \f(CW\*(C`long double\*(C'\fR or |
|
|
5458 | something like that, just kidding). |
4163 | .PP |
5459 | .PP |
4164 | If you know of other additional requirements drop me a note. |
5460 | If you know of other additional requirements drop me a note. |
4165 | .SH "ALGORITHMIC COMPLEXITIES" |
5461 | .SH "ALGORITHMIC COMPLEXITIES" |
4166 | .IX Header "ALGORITHMIC COMPLEXITIES" |
5462 | .IX Header "ALGORITHMIC COMPLEXITIES" |
4167 | In this section the complexities of (many of) the algorithms used inside |
5463 | In this section the complexities of (many of) the algorithms used inside |
… | |
… | |
4221 | .IX Item "Processing ev_async_send: O(number_of_async_watchers)" |
5517 | .IX Item "Processing ev_async_send: O(number_of_async_watchers)" |
4222 | .IP "Processing signals: O(max_signal_number)" 4 |
5518 | .IP "Processing signals: O(max_signal_number)" 4 |
4223 | .IX Item "Processing signals: O(max_signal_number)" |
5519 | .IX Item "Processing signals: O(max_signal_number)" |
4224 | .PD |
5520 | .PD |
4225 | Sending involves a system call \fIiff\fR there were no other \f(CW\*(C`ev_async_send\*(C'\fR |
5521 | Sending involves a system call \fIiff\fR there were no other \f(CW\*(C`ev_async_send\*(C'\fR |
4226 | calls in the current loop iteration. Checking for async and signal events |
5522 | calls in the current loop iteration and the loop is currently |
|
|
5523 | blocked. Checking for async and signal events involves iterating over all |
4227 | involves iterating over all running async watchers or all signal numbers. |
5524 | running async watchers or all signal numbers. |
|
|
5525 | .SH "PORTING FROM LIBEV 3.X TO 4.X" |
|
|
5526 | .IX Header "PORTING FROM LIBEV 3.X TO 4.X" |
|
|
5527 | The major version 4 introduced some incompatible changes to the \s-1API.\s0 |
|
|
5528 | .PP |
|
|
5529 | At the moment, the \f(CW\*(C`ev.h\*(C'\fR header file provides compatibility definitions |
|
|
5530 | for all changes, so most programs should still compile. The compatibility |
|
|
5531 | layer might be removed in later versions of libev, so better update to the |
|
|
5532 | new \s-1API\s0 early than late. |
|
|
5533 | .ie n .IP """EV_COMPAT3"" backwards compatibility mechanism" 4 |
|
|
5534 | .el .IP "\f(CWEV_COMPAT3\fR backwards compatibility mechanism" 4 |
|
|
5535 | .IX Item "EV_COMPAT3 backwards compatibility mechanism" |
|
|
5536 | The backward compatibility mechanism can be controlled by |
|
|
5537 | \&\f(CW\*(C`EV_COMPAT3\*(C'\fR. See \*(L"\s-1PREPROCESSOR SYMBOLS/MACROS\*(R"\s0 in the \*(L"\s-1EMBEDDING\*(R"\s0 |
|
|
5538 | section. |
|
|
5539 | .ie n .IP """ev_default_destroy"" and ""ev_default_fork"" have been removed" 4 |
|
|
5540 | .el .IP "\f(CWev_default_destroy\fR and \f(CWev_default_fork\fR have been removed" 4 |
|
|
5541 | .IX Item "ev_default_destroy and ev_default_fork have been removed" |
|
|
5542 | These calls can be replaced easily by their \f(CW\*(C`ev_loop_xxx\*(C'\fR counterparts: |
|
|
5543 | .Sp |
|
|
5544 | .Vb 2 |
|
|
5545 | \& ev_loop_destroy (EV_DEFAULT_UC); |
|
|
5546 | \& ev_loop_fork (EV_DEFAULT); |
|
|
5547 | .Ve |
|
|
5548 | .IP "function/symbol renames" 4 |
|
|
5549 | .IX Item "function/symbol renames" |
|
|
5550 | A number of functions and symbols have been renamed: |
|
|
5551 | .Sp |
|
|
5552 | .Vb 3 |
|
|
5553 | \& ev_loop => ev_run |
|
|
5554 | \& EVLOOP_NONBLOCK => EVRUN_NOWAIT |
|
|
5555 | \& EVLOOP_ONESHOT => EVRUN_ONCE |
|
|
5556 | \& |
|
|
5557 | \& ev_unloop => ev_break |
|
|
5558 | \& EVUNLOOP_CANCEL => EVBREAK_CANCEL |
|
|
5559 | \& EVUNLOOP_ONE => EVBREAK_ONE |
|
|
5560 | \& EVUNLOOP_ALL => EVBREAK_ALL |
|
|
5561 | \& |
|
|
5562 | \& EV_TIMEOUT => EV_TIMER |
|
|
5563 | \& |
|
|
5564 | \& ev_loop_count => ev_iteration |
|
|
5565 | \& ev_loop_depth => ev_depth |
|
|
5566 | \& ev_loop_verify => ev_verify |
|
|
5567 | .Ve |
|
|
5568 | .Sp |
|
|
5569 | Most functions working on \f(CW\*(C`struct ev_loop\*(C'\fR objects don't have an |
|
|
5570 | \&\f(CW\*(C`ev_loop_\*(C'\fR prefix, so it was removed; \f(CW\*(C`ev_loop\*(C'\fR, \f(CW\*(C`ev_unloop\*(C'\fR and |
|
|
5571 | associated constants have been renamed to not collide with the \f(CW\*(C`struct |
|
|
5572 | ev_loop\*(C'\fR anymore and \f(CW\*(C`EV_TIMER\*(C'\fR now follows the same naming scheme |
|
|
5573 | as all other watcher types. Note that \f(CW\*(C`ev_loop_fork\*(C'\fR is still called |
|
|
5574 | \&\f(CW\*(C`ev_loop_fork\*(C'\fR because it would otherwise clash with the \f(CW\*(C`ev_fork\*(C'\fR |
|
|
5575 | typedef. |
|
|
5576 | .ie n .IP """EV_MINIMAL"" mechanism replaced by ""EV_FEATURES""" 4 |
|
|
5577 | .el .IP "\f(CWEV_MINIMAL\fR mechanism replaced by \f(CWEV_FEATURES\fR" 4 |
|
|
5578 | .IX Item "EV_MINIMAL mechanism replaced by EV_FEATURES" |
|
|
5579 | The preprocessor symbol \f(CW\*(C`EV_MINIMAL\*(C'\fR has been replaced by a different |
|
|
5580 | mechanism, \f(CW\*(C`EV_FEATURES\*(C'\fR. Programs using \f(CW\*(C`EV_MINIMAL\*(C'\fR usually compile |
|
|
5581 | and work, but the library code will of course be larger. |
4228 | .SH "GLOSSARY" |
5582 | .SH "GLOSSARY" |
4229 | .IX Header "GLOSSARY" |
5583 | .IX Header "GLOSSARY" |
4230 | .IP "active" 4 |
5584 | .IP "active" 4 |
4231 | .IX Item "active" |
5585 | .IX Item "active" |
4232 | A watcher is active as long as it has been started (has been attached to |
5586 | A watcher is active as long as it has been started and not yet stopped. |
4233 | an event loop) but not yet stopped (disassociated from the event loop). |
5587 | See \*(L"\s-1WATCHER STATES\*(R"\s0 for details. |
4234 | .IP "application" 4 |
5588 | .IP "application" 4 |
4235 | .IX Item "application" |
5589 | .IX Item "application" |
4236 | In this document, an application is whatever is using libev. |
5590 | In this document, an application is whatever is using libev. |
|
|
5591 | .IP "backend" 4 |
|
|
5592 | .IX Item "backend" |
|
|
5593 | The part of the code dealing with the operating system interfaces. |
4237 | .IP "callback" 4 |
5594 | .IP "callback" 4 |
4238 | .IX Item "callback" |
5595 | .IX Item "callback" |
4239 | The address of a function that is called when some event has been |
5596 | The address of a function that is called when some event has been |
4240 | detected. Callbacks are being passed the event loop, the watcher that |
5597 | detected. Callbacks are being passed the event loop, the watcher that |
4241 | received the event, and the actual event bitset. |
5598 | received the event, and the actual event bitset. |
4242 | .IP "callback invocation" 4 |
5599 | .IP "callback/watcher invocation" 4 |
4243 | .IX Item "callback invocation" |
5600 | .IX Item "callback/watcher invocation" |
4244 | The act of calling the callback associated with a watcher. |
5601 | The act of calling the callback associated with a watcher. |
4245 | .IP "event" 4 |
5602 | .IP "event" 4 |
4246 | .IX Item "event" |
5603 | .IX Item "event" |
4247 | A change of state of some external event, such as data now being available |
5604 | A change of state of some external event, such as data now being available |
4248 | for reading on a file descriptor, time having passed or simply not having |
5605 | for reading on a file descriptor, time having passed or simply not having |
4249 | any other events happening anymore. |
5606 | any other events happening anymore. |
4250 | .Sp |
5607 | .Sp |
4251 | In libev, events are represented as single bits (such as \f(CW\*(C`EV_READ\*(C'\fR or |
5608 | In libev, events are represented as single bits (such as \f(CW\*(C`EV_READ\*(C'\fR or |
4252 | \&\f(CW\*(C`EV_TIMEOUT\*(C'\fR). |
5609 | \&\f(CW\*(C`EV_TIMER\*(C'\fR). |
4253 | .IP "event library" 4 |
5610 | .IP "event library" 4 |
4254 | .IX Item "event library" |
5611 | .IX Item "event library" |
4255 | A software package implementing an event model and loop. |
5612 | A software package implementing an event model and loop. |
4256 | .IP "event loop" 4 |
5613 | .IP "event loop" 4 |
4257 | .IX Item "event loop" |
5614 | .IX Item "event loop" |
… | |
… | |
4261 | .IX Item "event model" |
5618 | .IX Item "event model" |
4262 | The model used to describe how an event loop handles and processes |
5619 | The model used to describe how an event loop handles and processes |
4263 | watchers and events. |
5620 | watchers and events. |
4264 | .IP "pending" 4 |
5621 | .IP "pending" 4 |
4265 | .IX Item "pending" |
5622 | .IX Item "pending" |
4266 | A watcher is pending as soon as the corresponding event has been detected, |
5623 | A watcher is pending as soon as the corresponding event has been |
4267 | and stops being pending as soon as the watcher will be invoked or its |
5624 | detected. See \*(L"\s-1WATCHER STATES\*(R"\s0 for details. |
4268 | pending status is explicitly cleared by the application. |
|
|
4269 | .Sp |
|
|
4270 | A watcher can be pending, but not active. Stopping a watcher also clears |
|
|
4271 | its pending status. |
|
|
4272 | .IP "real time" 4 |
5625 | .IP "real time" 4 |
4273 | .IX Item "real time" |
5626 | .IX Item "real time" |
4274 | The physical time that is observed. It is apparently strictly monotonic :) |
5627 | The physical time that is observed. It is apparently strictly monotonic :) |
4275 | .IP "wall-clock time" 4 |
5628 | .IP "wall-clock time" 4 |
4276 | .IX Item "wall-clock time" |
5629 | .IX Item "wall-clock time" |
4277 | The time and date as shown on clocks. Unlike real time, it can actually |
5630 | The time and date as shown on clocks. Unlike real time, it can actually |
4278 | be wrong and jump forwards and backwards, e.g. when the you adjust your |
5631 | be wrong and jump forwards and backwards, e.g. when you adjust your |
4279 | clock. |
5632 | clock. |
4280 | .IP "watcher" 4 |
5633 | .IP "watcher" 4 |
4281 | .IX Item "watcher" |
5634 | .IX Item "watcher" |
4282 | A data structure that describes interest in certain events. Watchers need |
5635 | A data structure that describes interest in certain events. Watchers need |
4283 | to be started (attached to an event loop) before they can receive events. |
5636 | to be started (attached to an event loop) before they can receive events. |
4284 | .IP "watcher invocation" 4 |
|
|
4285 | .IX Item "watcher invocation" |
|
|
4286 | The act of calling the callback associated with a watcher. |
|
|
4287 | .SH "AUTHOR" |
5637 | .SH "AUTHOR" |
4288 | .IX Header "AUTHOR" |
5638 | .IX Header "AUTHOR" |
4289 | Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael Magnusson. |
5639 | Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael |
|
|
5640 | Magnusson and Emanuele Giaquinta, and minor corrections by many others. |