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12 | .. |
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134 | .IX Title "LIBEV 3" |
126 | .IX Title "LIBEV 3" |
135 | .TH LIBEV 3 "2008-11-17" "libev-3.49" "libev - high performance full featured event loop" |
127 | .TH LIBEV 3 "2011-02-16" "libev-4.04" "libev - high performance full featured event loop" |
136 | .\" For nroff, turn off justification. Always turn off hyphenation; it makes |
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138 | .if n .ad l |
130 | .if n .ad l |
139 | .nh |
131 | .nh |
140 | .SH "NAME" |
132 | .SH "NAME" |
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142 | .SH "SYNOPSIS" |
134 | .SH "SYNOPSIS" |
143 | .IX Header "SYNOPSIS" |
135 | .IX Header "SYNOPSIS" |
144 | .Vb 1 |
136 | .Vb 1 |
145 | \& #include <ev.h> |
137 | \& #include <ev.h> |
146 | .Ve |
138 | .Ve |
147 | .Sh "\s-1EXAMPLE\s0 \s-1PROGRAM\s0" |
139 | .SS "\s-1EXAMPLE\s0 \s-1PROGRAM\s0" |
148 | .IX Subsection "EXAMPLE PROGRAM" |
140 | .IX Subsection "EXAMPLE PROGRAM" |
149 | .Vb 2 |
141 | .Vb 2 |
150 | \& // a single header file is required |
142 | \& // a single header file is required |
151 | \& #include <ev.h> |
143 | \& #include <ev.h> |
152 | \& |
144 | \& |
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165 | \& puts ("stdin ready"); |
157 | \& puts ("stdin ready"); |
166 | \& // for one\-shot events, one must manually stop the watcher |
158 | \& // for one\-shot events, one must manually stop the watcher |
167 | \& // with its corresponding stop function. |
159 | \& // with its corresponding stop function. |
168 | \& ev_io_stop (EV_A_ w); |
160 | \& ev_io_stop (EV_A_ w); |
169 | \& |
161 | \& |
170 | \& // this causes all nested ev_loop\*(Aqs to stop iterating |
162 | \& // this causes all nested ev_run\*(Aqs to stop iterating |
171 | \& ev_unloop (EV_A_ EVUNLOOP_ALL); |
163 | \& ev_break (EV_A_ EVBREAK_ALL); |
172 | \& } |
164 | \& } |
173 | \& |
165 | \& |
174 | \& // another callback, this time for a time\-out |
166 | \& // another callback, this time for a time\-out |
175 | \& static void |
167 | \& static void |
176 | \& timeout_cb (EV_P_ ev_timer *w, int revents) |
168 | \& timeout_cb (EV_P_ ev_timer *w, int revents) |
177 | \& { |
169 | \& { |
178 | \& puts ("timeout"); |
170 | \& puts ("timeout"); |
179 | \& // this causes the innermost ev_loop to stop iterating |
171 | \& // this causes the innermost ev_run to stop iterating |
180 | \& ev_unloop (EV_A_ EVUNLOOP_ONE); |
172 | \& ev_break (EV_A_ EVBREAK_ONE); |
181 | \& } |
173 | \& } |
182 | \& |
174 | \& |
183 | \& int |
175 | \& int |
184 | \& main (void) |
176 | \& main (void) |
185 | \& { |
177 | \& { |
186 | \& // use the default event loop unless you have special needs |
178 | \& // use the default event loop unless you have special needs |
187 | \& ev_loop *loop = ev_default_loop (0); |
179 | \& struct ev_loop *loop = EV_DEFAULT; |
188 | \& |
180 | \& |
189 | \& // initialise an io watcher, then start it |
181 | \& // initialise an io watcher, then start it |
190 | \& // this one will watch for stdin to become readable |
182 | \& // this one will watch for stdin to become readable |
191 | \& ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ); |
183 | \& ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ); |
192 | \& ev_io_start (loop, &stdin_watcher); |
184 | \& ev_io_start (loop, &stdin_watcher); |
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195 | \& // simple non\-repeating 5.5 second timeout |
187 | \& // simple non\-repeating 5.5 second timeout |
196 | \& ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.); |
188 | \& ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.); |
197 | \& ev_timer_start (loop, &timeout_watcher); |
189 | \& ev_timer_start (loop, &timeout_watcher); |
198 | \& |
190 | \& |
199 | \& // now wait for events to arrive |
191 | \& // now wait for events to arrive |
200 | \& ev_loop (loop, 0); |
192 | \& ev_run (loop, 0); |
201 | \& |
193 | \& |
202 | \& // unloop was called, so exit |
194 | \& // break was called, so exit |
203 | \& return 0; |
195 | \& return 0; |
204 | \& } |
196 | \& } |
205 | .Ve |
197 | .Ve |
206 | .SH "DESCRIPTION" |
198 | .SH "ABOUT THIS DOCUMENT" |
207 | .IX Header "DESCRIPTION" |
199 | .IX Header "ABOUT THIS DOCUMENT" |
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200 | This document documents the libev software package. |
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201 | .PP |
208 | The newest version of this document is also available as an html-formatted |
202 | The newest version of this document is also available as an html-formatted |
209 | web page you might find easier to navigate when reading it for the first |
203 | web page you might find easier to navigate when reading it for the first |
210 | time: <http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod>. |
204 | time: <http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod>. |
211 | .PP |
205 | .PP |
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206 | While this document tries to be as complete as possible in documenting |
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207 | libev, its usage and the rationale behind its design, it is not a tutorial |
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208 | on event-based programming, nor will it introduce event-based programming |
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209 | with libev. |
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210 | .PP |
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211 | Familiarity with event based programming techniques in general is assumed |
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212 | throughout this document. |
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213 | .SH "WHAT TO READ WHEN IN A HURRY" |
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214 | .IX Header "WHAT TO READ WHEN IN A HURRY" |
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215 | This manual tries to be very detailed, but unfortunately, this also makes |
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216 | it very long. If you just want to know the basics of libev, I suggest |
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217 | reading \*(L"\s-1ANATOMY\s0 \s-1OF\s0 A \s-1WATCHER\s0\*(R", then the \*(L"\s-1EXAMPLE\s0 \s-1PROGRAM\s0\*(R" above and |
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218 | look up the missing functions in \*(L"\s-1GLOBAL\s0 \s-1FUNCTIONS\s0\*(R" and the \f(CW\*(C`ev_io\*(C'\fR and |
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219 | \&\f(CW\*(C`ev_timer\*(C'\fR sections in \*(L"\s-1WATCHER\s0 \s-1TYPES\s0\*(R". |
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220 | .SH "ABOUT LIBEV" |
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221 | .IX Header "ABOUT LIBEV" |
212 | Libev is an event loop: you register interest in certain events (such as a |
222 | Libev is an event loop: you register interest in certain events (such as a |
213 | file descriptor being readable or a timeout occurring), and it will manage |
223 | file descriptor being readable or a timeout occurring), and it will manage |
214 | these event sources and provide your program with events. |
224 | these event sources and provide your program with events. |
215 | .PP |
225 | .PP |
216 | To do this, it must take more or less complete control over your process |
226 | To do this, it must take more or less complete control over your process |
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219 | .PP |
229 | .PP |
220 | You register interest in certain events by registering so-called \fIevent |
230 | You register interest in certain events by registering so-called \fIevent |
221 | watchers\fR, which are relatively small C structures you initialise with the |
231 | watchers\fR, which are relatively small C structures you initialise with the |
222 | details of the event, and then hand it over to libev by \fIstarting\fR the |
232 | details of the event, and then hand it over to libev by \fIstarting\fR the |
223 | watcher. |
233 | watcher. |
224 | .Sh "\s-1FEATURES\s0" |
234 | .SS "\s-1FEATURES\s0" |
225 | .IX Subsection "FEATURES" |
235 | .IX Subsection "FEATURES" |
226 | Libev supports \f(CW\*(C`select\*(C'\fR, \f(CW\*(C`poll\*(C'\fR, the Linux-specific \f(CW\*(C`epoll\*(C'\fR, the |
236 | Libev supports \f(CW\*(C`select\*(C'\fR, \f(CW\*(C`poll\*(C'\fR, the Linux-specific \f(CW\*(C`epoll\*(C'\fR, the |
227 | BSD-specific \f(CW\*(C`kqueue\*(C'\fR and the Solaris-specific event port mechanisms |
237 | BSD-specific \f(CW\*(C`kqueue\*(C'\fR and the Solaris-specific event port mechanisms |
228 | for file descriptor events (\f(CW\*(C`ev_io\*(C'\fR), the Linux \f(CW\*(C`inotify\*(C'\fR interface |
238 | for file descriptor events (\f(CW\*(C`ev_io\*(C'\fR), the Linux \f(CW\*(C`inotify\*(C'\fR interface |
229 | (for \f(CW\*(C`ev_stat\*(C'\fR), relative timers (\f(CW\*(C`ev_timer\*(C'\fR), absolute timers |
239 | (for \f(CW\*(C`ev_stat\*(C'\fR), Linux eventfd/signalfd (for faster and cleaner |
230 | with customised rescheduling (\f(CW\*(C`ev_periodic\*(C'\fR), synchronous signals |
240 | inter-thread wakeup (\f(CW\*(C`ev_async\*(C'\fR)/signal handling (\f(CW\*(C`ev_signal\*(C'\fR)) relative |
231 | (\f(CW\*(C`ev_signal\*(C'\fR), process status change events (\f(CW\*(C`ev_child\*(C'\fR), and event |
241 | timers (\f(CW\*(C`ev_timer\*(C'\fR), absolute timers with customised rescheduling |
232 | watchers dealing with the event loop mechanism itself (\f(CW\*(C`ev_idle\*(C'\fR, |
242 | (\f(CW\*(C`ev_periodic\*(C'\fR), synchronous signals (\f(CW\*(C`ev_signal\*(C'\fR), process status |
233 | \&\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 |
243 | change events (\f(CW\*(C`ev_child\*(C'\fR), and event watchers dealing with the event |
234 | file watchers (\f(CW\*(C`ev_stat\*(C'\fR) and even limited support for fork events |
244 | 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 |
235 | (\f(CW\*(C`ev_fork\*(C'\fR). |
245 | \&\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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246 | limited support for fork events (\f(CW\*(C`ev_fork\*(C'\fR). |
236 | .PP |
247 | .PP |
237 | It also is quite fast (see this |
248 | It also is quite fast (see this |
238 | benchmark comparing it to libevent |
249 | <benchmark> comparing it to libevent |
239 | for example). |
250 | for example). |
240 | .Sh "\s-1CONVENTIONS\s0" |
251 | .SS "\s-1CONVENTIONS\s0" |
241 | .IX Subsection "CONVENTIONS" |
252 | .IX Subsection "CONVENTIONS" |
242 | Libev is very configurable. In this manual the default (and most common) |
253 | Libev is very configurable. In this manual the default (and most common) |
243 | configuration will be described, which supports multiple event loops. For |
254 | configuration will be described, which supports multiple event loops. For |
244 | more info about various configuration options please have a look at |
255 | more info about various configuration options please have a look at |
245 | \&\fB\s-1EMBED\s0\fR section in this manual. If libev was configured without support |
256 | \&\fB\s-1EMBED\s0\fR section in this manual. If libev was configured without support |
246 | for multiple event loops, then all functions taking an initial argument of |
257 | for multiple event loops, then all functions taking an initial argument of |
247 | name \f(CW\*(C`loop\*(C'\fR (which is always of type \f(CW\*(C`ev_loop *\*(C'\fR) will not have |
258 | name \f(CW\*(C`loop\*(C'\fR (which is always of type \f(CW\*(C`struct ev_loop *\*(C'\fR) will not have |
248 | this argument. |
259 | this argument. |
249 | .Sh "\s-1TIME\s0 \s-1REPRESENTATION\s0" |
260 | .SS "\s-1TIME\s0 \s-1REPRESENTATION\s0" |
250 | .IX Subsection "TIME REPRESENTATION" |
261 | .IX Subsection "TIME REPRESENTATION" |
251 | Libev represents time as a single floating point number, representing the |
262 | Libev represents time as a single floating point number, representing |
252 | (fractional) number of seconds since the (\s-1POSIX\s0) epoch (somewhere near |
263 | the (fractional) number of seconds since the (\s-1POSIX\s0) epoch (in practice |
253 | the beginning of 1970, details are complicated, don't ask). This type is |
264 | somewhere near the beginning of 1970, details are complicated, don't |
254 | called \f(CW\*(C`ev_tstamp\*(C'\fR, which is what you should use too. It usually aliases |
265 | ask). This type is called \f(CW\*(C`ev_tstamp\*(C'\fR, which is what you should use |
255 | to the \f(CW\*(C`double\*(C'\fR type in C, and when you need to do any calculations on |
266 | too. It usually aliases to the \f(CW\*(C`double\*(C'\fR type in C. When you need to do |
256 | it, you should treat it as some floating point value. Unlike the name |
267 | any calculations on it, you should treat it as some floating point value. |
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268 | .PP |
257 | component \f(CW\*(C`stamp\*(C'\fR might indicate, it is also used for time differences |
269 | Unlike the name component \f(CW\*(C`stamp\*(C'\fR might indicate, it is also used for |
258 | throughout libev. |
270 | time differences (e.g. delays) throughout libev. |
259 | .SH "ERROR HANDLING" |
271 | .SH "ERROR HANDLING" |
260 | .IX Header "ERROR HANDLING" |
272 | .IX Header "ERROR HANDLING" |
261 | Libev knows three classes of errors: operating system errors, usage errors |
273 | Libev knows three classes of errors: operating system errors, usage errors |
262 | and internal errors (bugs). |
274 | and internal errors (bugs). |
263 | .PP |
275 | .PP |
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281 | library in any way. |
293 | library in any way. |
282 | .IP "ev_tstamp ev_time ()" 4 |
294 | .IP "ev_tstamp ev_time ()" 4 |
283 | .IX Item "ev_tstamp ev_time ()" |
295 | .IX Item "ev_tstamp ev_time ()" |
284 | Returns the current time as libev would use it. Please note that the |
296 | Returns the current time as libev would use it. Please note that the |
285 | \&\f(CW\*(C`ev_now\*(C'\fR function is usually faster and also often returns the timestamp |
297 | \&\f(CW\*(C`ev_now\*(C'\fR function is usually faster and also often returns the timestamp |
286 | you actually want to know. |
298 | you actually want to know. Also interesting is the combination of |
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299 | \&\f(CW\*(C`ev_update_now\*(C'\fR and \f(CW\*(C`ev_now\*(C'\fR. |
287 | .IP "ev_sleep (ev_tstamp interval)" 4 |
300 | .IP "ev_sleep (ev_tstamp interval)" 4 |
288 | .IX Item "ev_sleep (ev_tstamp interval)" |
301 | .IX Item "ev_sleep (ev_tstamp interval)" |
289 | Sleep for the given interval: The current thread will be blocked until |
302 | Sleep for the given interval: The current thread will be blocked until |
290 | either it is interrupted or the given time interval has passed. Basically |
303 | either it is interrupted or the given time interval has passed. Basically |
291 | this is a sub-second-resolution \f(CW\*(C`sleep ()\*(C'\fR. |
304 | this is a sub-second-resolution \f(CW\*(C`sleep ()\*(C'\fR. |
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308 | as this indicates an incompatible change. Minor versions are usually |
321 | as this indicates an incompatible change. Minor versions are usually |
309 | compatible to older versions, so a larger minor version alone is usually |
322 | compatible to older versions, so a larger minor version alone is usually |
310 | not a problem. |
323 | not a problem. |
311 | .Sp |
324 | .Sp |
312 | Example: Make sure we haven't accidentally been linked against the wrong |
325 | Example: Make sure we haven't accidentally been linked against the wrong |
313 | version. |
326 | version (note, however, that this will not detect other \s-1ABI\s0 mismatches, |
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327 | such as \s-1LFS\s0 or reentrancy). |
314 | .Sp |
328 | .Sp |
315 | .Vb 3 |
329 | .Vb 3 |
316 | \& assert (("libev version mismatch", |
330 | \& assert (("libev version mismatch", |
317 | \& ev_version_major () == EV_VERSION_MAJOR |
331 | \& ev_version_major () == EV_VERSION_MAJOR |
318 | \& && ev_version_minor () >= EV_VERSION_MINOR)); |
332 | \& && ev_version_minor () >= EV_VERSION_MINOR)); |
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331 | \& assert (("sorry, no epoll, no sex", |
345 | \& assert (("sorry, no epoll, no sex", |
332 | \& ev_supported_backends () & EVBACKEND_EPOLL)); |
346 | \& ev_supported_backends () & EVBACKEND_EPOLL)); |
333 | .Ve |
347 | .Ve |
334 | .IP "unsigned int ev_recommended_backends ()" 4 |
348 | .IP "unsigned int ev_recommended_backends ()" 4 |
335 | .IX Item "unsigned int ev_recommended_backends ()" |
349 | .IX Item "unsigned int ev_recommended_backends ()" |
336 | Return the set of all backends compiled into this binary of libev and also |
350 | Return the set of all backends compiled into this binary of libev and |
337 | recommended for this platform. This set is often smaller than the one |
351 | also recommended for this platform, meaning it will work for most file |
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352 | descriptor types. This set is often smaller than the one returned by |
338 | returned by \f(CW\*(C`ev_supported_backends\*(C'\fR, as for example kqueue is broken on |
353 | \&\f(CW\*(C`ev_supported_backends\*(C'\fR, as for example kqueue is broken on most BSDs |
339 | most BSDs and will not be auto-detected unless you explicitly request it |
354 | and will not be auto-detected unless you explicitly request it (assuming |
340 | (assuming you know what you are doing). This is the set of backends that |
355 | you know what you are doing). This is the set of backends that libev will |
341 | libev will probe for if you specify no backends explicitly. |
356 | probe for if you specify no backends explicitly. |
342 | .IP "unsigned int ev_embeddable_backends ()" 4 |
357 | .IP "unsigned int ev_embeddable_backends ()" 4 |
343 | .IX Item "unsigned int ev_embeddable_backends ()" |
358 | .IX Item "unsigned int ev_embeddable_backends ()" |
344 | Returns the set of backends that are embeddable in other event loops. This |
359 | Returns the set of backends that are embeddable in other event loops. This |
345 | is the theoretical, all-platform, value. To find which backends |
360 | value is platform-specific but can include backends not available on the |
346 | might be supported on the current system, you would need to look at |
361 | current system. To find which embeddable backends might be supported on |
347 | \&\f(CW\*(C`ev_embeddable_backends () & ev_supported_backends ()\*(C'\fR, likewise for |
362 | the current system, you would need to look at \f(CW\*(C`ev_embeddable_backends () |
348 | recommended ones. |
363 | & ev_supported_backends ()\*(C'\fR, likewise for recommended ones. |
349 | .Sp |
364 | .Sp |
350 | See the description of \f(CW\*(C`ev_embed\*(C'\fR watchers for more info. |
365 | See the description of \f(CW\*(C`ev_embed\*(C'\fR watchers for more info. |
351 | .IP "ev_set_allocator (void *(*cb)(void *ptr, long size)) [\s-1NOT\s0 \s-1REENTRANT\s0]" 4 |
366 | .IP "ev_set_allocator (void *(*cb)(void *ptr, long size))" 4 |
352 | .IX Item "ev_set_allocator (void *(*cb)(void *ptr, long size)) [NOT REENTRANT]" |
367 | .IX Item "ev_set_allocator (void *(*cb)(void *ptr, long size))" |
353 | Sets the allocation function to use (the prototype is similar \- the |
368 | Sets the allocation function to use (the prototype is similar \- the |
354 | semantics are identical to the \f(CW\*(C`realloc\*(C'\fR C89/SuS/POSIX function). It is |
369 | semantics are identical to the \f(CW\*(C`realloc\*(C'\fR C89/SuS/POSIX function). It is |
355 | used to allocate and free memory (no surprises here). If it returns zero |
370 | used to allocate and free memory (no surprises here). If it returns zero |
356 | when memory needs to be allocated (\f(CW\*(C`size != 0\*(C'\fR), the library might abort |
371 | when memory needs to be allocated (\f(CW\*(C`size != 0\*(C'\fR), the library might abort |
357 | or take some potentially destructive action. |
372 | or take some potentially destructive action. |
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383 | \& } |
398 | \& } |
384 | \& |
399 | \& |
385 | \& ... |
400 | \& ... |
386 | \& ev_set_allocator (persistent_realloc); |
401 | \& ev_set_allocator (persistent_realloc); |
387 | .Ve |
402 | .Ve |
388 | .IP "ev_set_syserr_cb (void (*cb)(const char *msg)); [\s-1NOT\s0 \s-1REENTRANT\s0]" 4 |
403 | .IP "ev_set_syserr_cb (void (*cb)(const char *msg))" 4 |
389 | .IX Item "ev_set_syserr_cb (void (*cb)(const char *msg)); [NOT REENTRANT]" |
404 | .IX Item "ev_set_syserr_cb (void (*cb)(const char *msg))" |
390 | Set the callback function to call on a retryable system call error (such |
405 | Set the callback function to call on a retryable system call error (such |
391 | as failed select, poll, epoll_wait). The message is a printable string |
406 | as failed select, poll, epoll_wait). The message is a printable string |
392 | indicating the system call or subsystem causing the problem. If this |
407 | indicating the system call or subsystem causing the problem. If this |
393 | callback is set, then libev will expect it to remedy the situation, no |
408 | callback is set, then libev will expect it to remedy the situation, no |
394 | matter what, when it returns. That is, libev will generally retry the |
409 | matter what, when it returns. That is, libev will generally retry the |
… | |
… | |
406 | \& } |
421 | \& } |
407 | \& |
422 | \& |
408 | \& ... |
423 | \& ... |
409 | \& ev_set_syserr_cb (fatal_error); |
424 | \& ev_set_syserr_cb (fatal_error); |
410 | .Ve |
425 | .Ve |
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426 | .IP "ev_feed_signal (int signum)" 4 |
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427 | .IX Item "ev_feed_signal (int signum)" |
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428 | This function can be used to \*(L"simulate\*(R" a signal receive. It is completely |
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429 | safe to call this function at any time, from any context, including signal |
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430 | handlers or random threads. |
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431 | .Sp |
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432 | Its main use is to customise signal handling in your process, especially |
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433 | in the presence of threads. For example, you could block signals |
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434 | by default in all threads (and specifying \f(CW\*(C`EVFLAG_NOSIGMASK\*(C'\fR when |
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435 | creating any loops), and in one thread, use \f(CW\*(C`sigwait\*(C'\fR or any other |
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436 | mechanism to wait for signals, then \*(L"deliver\*(R" them to libev by calling |
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437 | \&\f(CW\*(C`ev_feed_signal\*(C'\fR. |
411 | .SH "FUNCTIONS CONTROLLING THE EVENT LOOP" |
438 | .SH "FUNCTIONS CONTROLLING EVENT LOOPS" |
412 | .IX Header "FUNCTIONS CONTROLLING THE EVENT LOOP" |
439 | .IX Header "FUNCTIONS CONTROLLING EVENT LOOPS" |
413 | An event loop is described by a \f(CW\*(C`struct ev_loop *\*(C'\fR (the \f(CW\*(C`struct\*(C'\fR |
440 | An event loop is described by a \f(CW\*(C`struct ev_loop *\*(C'\fR (the \f(CW\*(C`struct\*(C'\fR is |
414 | is \fInot\fR optional in this case, as there is also an \f(CW\*(C`ev_loop\*(C'\fR |
441 | \&\fInot\fR optional in this case unless libev 3 compatibility is disabled, as |
415 | \&\fIfunction\fR). |
442 | libev 3 had an \f(CW\*(C`ev_loop\*(C'\fR function colliding with the struct name). |
416 | .PP |
443 | .PP |
417 | The library knows two types of such loops, the \fIdefault\fR loop, which |
444 | The library knows two types of such loops, the \fIdefault\fR loop, which |
418 | supports signals and child events, and dynamically created loops which do |
445 | supports child process events, and dynamically created event loops which |
419 | not. |
446 | do not. |
420 | .IP "struct ev_loop *ev_default_loop (unsigned int flags)" 4 |
447 | .IP "struct ev_loop *ev_default_loop (unsigned int flags)" 4 |
421 | .IX Item "struct ev_loop *ev_default_loop (unsigned int flags)" |
448 | .IX Item "struct ev_loop *ev_default_loop (unsigned int flags)" |
422 | This will initialise the default event loop if it hasn't been initialised |
449 | This returns the \*(L"default\*(R" event loop object, which is what you should |
423 | yet and return it. If the default loop could not be initialised, returns |
450 | normally use when you just need \*(L"the event loop\*(R". Event loop objects and |
424 | false. If it already was initialised it simply returns it (and ignores the |
451 | the \f(CW\*(C`flags\*(C'\fR parameter are described in more detail in the entry for |
425 | flags. If that is troubling you, check \f(CW\*(C`ev_backend ()\*(C'\fR afterwards). |
452 | \&\f(CW\*(C`ev_loop_new\*(C'\fR. |
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453 | .Sp |
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454 | If the default loop is already initialised then this function simply |
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455 | returns it (and ignores the flags. If that is troubling you, check |
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456 | \&\f(CW\*(C`ev_backend ()\*(C'\fR afterwards). Otherwise it will create it with the given |
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457 | flags, which should almost always be \f(CW0\fR, unless the caller is also the |
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458 | one calling \f(CW\*(C`ev_run\*(C'\fR or otherwise qualifies as \*(L"the main program\*(R". |
426 | .Sp |
459 | .Sp |
427 | If you don't know what event loop to use, use the one returned from this |
460 | If you don't know what event loop to use, use the one returned from this |
428 | function. |
461 | function (or via the \f(CW\*(C`EV_DEFAULT\*(C'\fR macro). |
429 | .Sp |
462 | .Sp |
430 | Note that this function is \fInot\fR thread-safe, so if you want to use it |
463 | Note that this function is \fInot\fR thread-safe, so if you want to use it |
431 | from multiple threads, you have to lock (note also that this is unlikely, |
464 | from multiple threads, you have to employ some kind of mutex (note also |
432 | as loops cannot be shared easily between threads anyway). |
465 | that this case is unlikely, as loops cannot be shared easily between |
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466 | threads anyway). |
433 | .Sp |
467 | .Sp |
434 | The default loop is the only loop that can handle \f(CW\*(C`ev_signal\*(C'\fR and |
468 | The default loop is the only loop that can handle \f(CW\*(C`ev_child\*(C'\fR watchers, |
435 | \&\f(CW\*(C`ev_child\*(C'\fR watchers, and to do this, it always registers a handler |
469 | and to do this, it always registers a handler for \f(CW\*(C`SIGCHLD\*(C'\fR. If this is |
436 | for \f(CW\*(C`SIGCHLD\*(C'\fR. If this is a problem for your application you can either |
470 | a problem for your application you can either create a dynamic loop with |
437 | create a dynamic loop with \f(CW\*(C`ev_loop_new\*(C'\fR that doesn't do that, or you |
471 | \&\f(CW\*(C`ev_loop_new\*(C'\fR which doesn't do that, or you can simply overwrite the |
438 | can simply overwrite the \f(CW\*(C`SIGCHLD\*(C'\fR signal handler \fIafter\fR calling |
472 | \&\f(CW\*(C`SIGCHLD\*(C'\fR signal handler \fIafter\fR calling \f(CW\*(C`ev_default_init\*(C'\fR. |
439 | \&\f(CW\*(C`ev_default_init\*(C'\fR. |
473 | .Sp |
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474 | Example: This is the most typical usage. |
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475 | .Sp |
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476 | .Vb 2 |
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477 | \& if (!ev_default_loop (0)) |
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478 | \& fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?"); |
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479 | .Ve |
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480 | .Sp |
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481 | Example: Restrict libev to the select and poll backends, and do not allow |
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482 | environment settings to be taken into account: |
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483 | .Sp |
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484 | .Vb 1 |
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485 | \& ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV); |
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486 | .Ve |
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487 | .IP "struct ev_loop *ev_loop_new (unsigned int flags)" 4 |
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488 | .IX Item "struct ev_loop *ev_loop_new (unsigned int flags)" |
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489 | This will create and initialise a new event loop object. If the loop |
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490 | could not be initialised, returns false. |
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491 | .Sp |
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492 | This function is thread-safe, and one common way to use libev with |
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493 | threads is indeed to create one loop per thread, and using the default |
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494 | loop in the \*(L"main\*(R" or \*(L"initial\*(R" thread. |
440 | .Sp |
495 | .Sp |
441 | The flags argument can be used to specify special behaviour or specific |
496 | The flags argument can be used to specify special behaviour or specific |
442 | backends to use, and is usually specified as \f(CW0\fR (or \f(CW\*(C`EVFLAG_AUTO\*(C'\fR). |
497 | backends to use, and is usually specified as \f(CW0\fR (or \f(CW\*(C`EVFLAG_AUTO\*(C'\fR). |
443 | .Sp |
498 | .Sp |
444 | The following flags are supported: |
499 | The following flags are supported: |
… | |
… | |
458 | useful to try out specific backends to test their performance, or to work |
513 | useful to try out specific backends to test their performance, or to work |
459 | around bugs. |
514 | around bugs. |
460 | .ie n .IP """EVFLAG_FORKCHECK""" 4 |
515 | .ie n .IP """EVFLAG_FORKCHECK""" 4 |
461 | .el .IP "\f(CWEVFLAG_FORKCHECK\fR" 4 |
516 | .el .IP "\f(CWEVFLAG_FORKCHECK\fR" 4 |
462 | .IX Item "EVFLAG_FORKCHECK" |
517 | .IX Item "EVFLAG_FORKCHECK" |
463 | Instead of calling \f(CW\*(C`ev_default_fork\*(C'\fR or \f(CW\*(C`ev_loop_fork\*(C'\fR manually after |
518 | Instead of calling \f(CW\*(C`ev_loop_fork\*(C'\fR manually after a fork, you can also |
464 | a fork, you can also make libev check for a fork in each iteration by |
519 | make libev check for a fork in each iteration by enabling this flag. |
465 | enabling this flag. |
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|
466 | .Sp |
520 | .Sp |
467 | This works by calling \f(CW\*(C`getpid ()\*(C'\fR on every iteration of the loop, |
521 | This works by calling \f(CW\*(C`getpid ()\*(C'\fR on every iteration of the loop, |
468 | and thus this might slow down your event loop if you do a lot of loop |
522 | and thus this might slow down your event loop if you do a lot of loop |
469 | iterations and little real work, but is usually not noticeable (on my |
523 | iterations and little real work, but is usually not noticeable (on my |
470 | GNU/Linux system for example, \f(CW\*(C`getpid\*(C'\fR is actually a simple 5\-insn sequence |
524 | GNU/Linux system for example, \f(CW\*(C`getpid\*(C'\fR is actually a simple 5\-insn sequence |
… | |
… | |
475 | forget about forgetting to tell libev about forking) when you use this |
529 | forget about forgetting to tell libev about forking) when you use this |
476 | flag. |
530 | flag. |
477 | .Sp |
531 | .Sp |
478 | This flag setting cannot be overridden or specified in the \f(CW\*(C`LIBEV_FLAGS\*(C'\fR |
532 | This flag setting cannot be overridden or specified in the \f(CW\*(C`LIBEV_FLAGS\*(C'\fR |
479 | environment variable. |
533 | environment variable. |
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|
534 | .ie n .IP """EVFLAG_NOINOTIFY""" 4 |
|
|
535 | .el .IP "\f(CWEVFLAG_NOINOTIFY\fR" 4 |
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536 | .IX Item "EVFLAG_NOINOTIFY" |
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537 | When this flag is specified, then libev will not attempt to use the |
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538 | \&\fIinotify\fR \s-1API\s0 for its \f(CW\*(C`ev_stat\*(C'\fR watchers. Apart from debugging and |
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539 | testing, this flag can be useful to conserve inotify file descriptors, as |
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540 | otherwise each loop using \f(CW\*(C`ev_stat\*(C'\fR watchers consumes one inotify handle. |
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541 | .ie n .IP """EVFLAG_SIGNALFD""" 4 |
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|
542 | .el .IP "\f(CWEVFLAG_SIGNALFD\fR" 4 |
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|
543 | .IX Item "EVFLAG_SIGNALFD" |
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544 | When this flag is specified, then libev will attempt to use the |
|
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545 | \&\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 |
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546 | delivers signals synchronously, which makes it both faster and might make |
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547 | it possible to get the queued signal data. It can also simplify signal |
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548 | handling with threads, as long as you properly block signals in your |
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549 | threads that are not interested in handling them. |
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550 | .Sp |
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551 | Signalfd will not be used by default as this changes your signal mask, and |
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552 | there are a lot of shoddy libraries and programs (glib's threadpool for |
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553 | example) that can't properly initialise their signal masks. |
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554 | .ie n .IP """EVFLAG_NOSIGMASK""" 4 |
|
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555 | .el .IP "\f(CWEVFLAG_NOSIGMASK\fR" 4 |
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|
556 | .IX Item "EVFLAG_NOSIGMASK" |
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557 | When this flag is specified, then libev will avoid to modify the signal |
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558 | mask. Specifically, this means you ahve to make sure signals are unblocked |
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559 | when you want to receive them. |
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560 | .Sp |
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561 | This behaviour is useful when you want to do your own signal handling, or |
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562 | want to handle signals only in specific threads and want to avoid libev |
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563 | unblocking the signals. |
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564 | .Sp |
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565 | It's also required by \s-1POSIX\s0 in a threaded program, as libev calls |
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566 | \&\f(CW\*(C`sigprocmask\*(C'\fR, whose behaviour is officially unspecified. |
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567 | .Sp |
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|
568 | This flag's behaviour will become the default in future versions of libev. |
480 | .ie n .IP """EVBACKEND_SELECT"" (value 1, portable select backend)" 4 |
569 | .ie n .IP """EVBACKEND_SELECT"" (value 1, portable select backend)" 4 |
481 | .el .IP "\f(CWEVBACKEND_SELECT\fR (value 1, portable select backend)" 4 |
570 | .el .IP "\f(CWEVBACKEND_SELECT\fR (value 1, portable select backend)" 4 |
482 | .IX Item "EVBACKEND_SELECT (value 1, portable select backend)" |
571 | .IX Item "EVBACKEND_SELECT (value 1, portable select backend)" |
483 | This is your standard \fIselect\fR\|(2) backend. Not \fIcompletely\fR standard, as |
572 | This is your standard \fIselect\fR\|(2) backend. Not \fIcompletely\fR standard, as |
484 | libev tries to roll its own fd_set with no limits on the number of fds, |
573 | libev tries to roll its own fd_set with no limits on the number of fds, |
… | |
… | |
509 | This backend maps \f(CW\*(C`EV_READ\*(C'\fR to \f(CW\*(C`POLLIN | POLLERR | POLLHUP\*(C'\fR, and |
598 | This backend maps \f(CW\*(C`EV_READ\*(C'\fR to \f(CW\*(C`POLLIN | POLLERR | POLLHUP\*(C'\fR, and |
510 | \&\f(CW\*(C`EV_WRITE\*(C'\fR to \f(CW\*(C`POLLOUT | POLLERR | POLLHUP\*(C'\fR. |
599 | \&\f(CW\*(C`EV_WRITE\*(C'\fR to \f(CW\*(C`POLLOUT | POLLERR | POLLHUP\*(C'\fR. |
511 | .ie n .IP """EVBACKEND_EPOLL"" (value 4, Linux)" 4 |
600 | .ie n .IP """EVBACKEND_EPOLL"" (value 4, Linux)" 4 |
512 | .el .IP "\f(CWEVBACKEND_EPOLL\fR (value 4, Linux)" 4 |
601 | .el .IP "\f(CWEVBACKEND_EPOLL\fR (value 4, Linux)" 4 |
513 | .IX Item "EVBACKEND_EPOLL (value 4, Linux)" |
602 | .IX Item "EVBACKEND_EPOLL (value 4, Linux)" |
|
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603 | Use the linux-specific \fIepoll\fR\|(7) interface (for both pre\- and post\-2.6.9 |
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604 | kernels). |
|
|
605 | .Sp |
514 | For few fds, this backend is a bit little slower than poll and select, |
606 | For few fds, this backend is a bit little slower than poll and select, |
515 | but it scales phenomenally better. While poll and select usually scale |
607 | but it scales phenomenally better. While poll and select usually scale |
516 | like O(total_fds) where n is the total number of fds (or the highest fd), |
608 | like O(total_fds) where n is the total number of fds (or the highest fd), |
517 | epoll scales either O(1) or O(active_fds). |
609 | epoll scales either O(1) or O(active_fds). |
518 | .Sp |
610 | .Sp |
519 | The epoll mechanism deserves honorable mention as the most misdesigned |
611 | The epoll mechanism deserves honorable mention as the most misdesigned |
520 | of the more advanced event mechanisms: mere annoyances include silently |
612 | of the more advanced event mechanisms: mere annoyances include silently |
521 | dropping file descriptors, requiring a system call per change per file |
613 | dropping file descriptors, requiring a system call per change per file |
522 | descriptor (and unnecessary guessing of parameters), problems with dup and |
614 | descriptor (and unnecessary guessing of parameters), problems with dup, |
|
|
615 | returning before the timeout value, resulting in additional iterations |
|
|
616 | (and only giving 5ms accuracy while select on the same platform gives |
523 | so on. The biggest issue is fork races, however \- if a program forks then |
617 | 0.1ms) and so on. The biggest issue is fork races, however \- if a program |
524 | \&\fIboth\fR parent and child process have to recreate the epoll set, which can |
618 | forks then \fIboth\fR parent and child process have to recreate the epoll |
525 | take considerable time (one syscall per file descriptor) and is of course |
619 | set, which can take considerable time (one syscall per file descriptor) |
526 | hard to detect. |
620 | and is of course hard to detect. |
527 | .Sp |
621 | .Sp |
528 | Epoll is also notoriously buggy \- embedding epoll fds \fIshould\fR work, but |
622 | Epoll is also notoriously buggy \- embedding epoll fds \fIshould\fR work, but |
529 | of course \fIdoesn't\fR, and epoll just loves to report events for totally |
623 | of course \fIdoesn't\fR, and epoll just loves to report events for totally |
530 | \&\fIdifferent\fR file descriptors (even already closed ones, so one cannot |
624 | \&\fIdifferent\fR file descriptors (even already closed ones, so one cannot |
531 | even remove them from the set) than registered in the set (especially |
625 | even remove them from the set) than registered in the set (especially |
532 | on \s-1SMP\s0 systems). Libev tries to counter these spurious notifications by |
626 | on \s-1SMP\s0 systems). Libev tries to counter these spurious notifications by |
533 | employing an additional generation counter and comparing that against the |
627 | employing an additional generation counter and comparing that against the |
534 | events to filter out spurious ones, recreating the set when required. |
628 | events to filter out spurious ones, recreating the set when required. Last |
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629 | not least, it also refuses to work with some file descriptors which work |
|
|
630 | perfectly fine with \f(CW\*(C`select\*(C'\fR (files, many character devices...). |
|
|
631 | .Sp |
|
|
632 | Epoll is truly the train wreck analog among event poll mechanisms, |
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633 | a frankenpoll, cobbled together in a hurry, no thought to design or |
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|
634 | interaction with others. |
535 | .Sp |
635 | .Sp |
536 | While stopping, setting and starting an I/O watcher in the same iteration |
636 | While stopping, setting and starting an I/O watcher in the same iteration |
537 | will result in some caching, there is still a system call per such |
637 | will result in some caching, there is still a system call per such |
538 | incident (because the same \fIfile descriptor\fR could point to a different |
638 | incident (because the same \fIfile descriptor\fR could point to a different |
539 | \&\fIfile description\fR now), so its best to avoid that. Also, \f(CW\*(C`dup ()\*(C'\fR'ed |
639 | \&\fIfile description\fR now), so its best to avoid that. Also, \f(CW\*(C`dup ()\*(C'\fR'ed |
… | |
… | |
586 | .Sp |
686 | .Sp |
587 | While nominally embeddable in other event loops, this doesn't work |
687 | While nominally embeddable in other event loops, this doesn't work |
588 | everywhere, so you might need to test for this. And since it is broken |
688 | everywhere, so you might need to test for this. And since it is broken |
589 | almost everywhere, you should only use it when you have a lot of sockets |
689 | almost everywhere, you should only use it when you have a lot of sockets |
590 | (for which it usually works), by embedding it into another event loop |
690 | (for which it usually works), by embedding it into another event loop |
591 | (e.g. \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or \f(CW\*(C`EVBACKEND_POLL\*(C'\fR) and, did I mention it, |
691 | (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 |
592 | using it only for sockets. |
692 | also broken on \s-1OS\s0 X)) and, did I mention it, using it only for sockets. |
593 | .Sp |
693 | .Sp |
594 | This backend maps \f(CW\*(C`EV_READ\*(C'\fR into an \f(CW\*(C`EVFILT_READ\*(C'\fR kevent with |
694 | This backend maps \f(CW\*(C`EV_READ\*(C'\fR into an \f(CW\*(C`EVFILT_READ\*(C'\fR kevent with |
595 | \&\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 |
695 | \&\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 |
596 | \&\f(CW\*(C`NOTE_EOF\*(C'\fR. |
696 | \&\f(CW\*(C`NOTE_EOF\*(C'\fR. |
597 | .ie n .IP """EVBACKEND_DEVPOLL"" (value 16, Solaris 8)" 4 |
697 | .ie n .IP """EVBACKEND_DEVPOLL"" (value 16, Solaris 8)" 4 |
… | |
… | |
605 | .el .IP "\f(CWEVBACKEND_PORT\fR (value 32, Solaris 10)" 4 |
705 | .el .IP "\f(CWEVBACKEND_PORT\fR (value 32, Solaris 10)" 4 |
606 | .IX Item "EVBACKEND_PORT (value 32, Solaris 10)" |
706 | .IX Item "EVBACKEND_PORT (value 32, Solaris 10)" |
607 | This uses the Solaris 10 event port mechanism. As with everything on Solaris, |
707 | This uses the Solaris 10 event port mechanism. As with everything on Solaris, |
608 | it's really slow, but it still scales very well (O(active_fds)). |
708 | it's really slow, but it still scales very well (O(active_fds)). |
609 | .Sp |
709 | .Sp |
610 | Please note that Solaris event ports can deliver a lot of spurious |
|
|
611 | notifications, so you need to use non-blocking I/O or other means to avoid |
|
|
612 | blocking when no data (or space) is available. |
|
|
613 | .Sp |
|
|
614 | While this backend scales well, it requires one system call per active |
710 | While this backend scales well, it requires one system call per active |
615 | file descriptor per loop iteration. For small and medium numbers of file |
711 | file descriptor per loop iteration. For small and medium numbers of file |
616 | descriptors a \*(L"slow\*(R" \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or \f(CW\*(C`EVBACKEND_POLL\*(C'\fR backend |
712 | descriptors a \*(L"slow\*(R" \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or \f(CW\*(C`EVBACKEND_POLL\*(C'\fR backend |
617 | might perform better. |
713 | might perform better. |
618 | .Sp |
714 | .Sp |
619 | On the positive side, with the exception of the spurious readiness |
715 | On the positive side, this backend actually performed fully to |
620 | notifications, this backend actually performed fully to specification |
|
|
621 | in all tests and is fully embeddable, which is a rare feat among the |
716 | specification in all tests and is fully embeddable, which is a rare feat |
622 | OS-specific backends (I vastly prefer correctness over speed hacks). |
717 | among the OS-specific backends (I vastly prefer correctness over speed |
|
|
718 | hacks). |
|
|
719 | .Sp |
|
|
720 | On the negative side, the interface is \fIbizarre\fR \- so bizarre that |
|
|
721 | even sun itself gets it wrong in their code examples: The event polling |
|
|
722 | function sometimes returning events to the caller even though an error |
|
|
723 | occurred, but with no indication whether it has done so or not (yes, it's |
|
|
724 | even documented that way) \- deadly for edge-triggered interfaces where |
|
|
725 | you absolutely have to know whether an event occurred or not because you |
|
|
726 | have to re-arm the watcher. |
|
|
727 | .Sp |
|
|
728 | Fortunately libev seems to be able to work around these idiocies. |
623 | .Sp |
729 | .Sp |
624 | This backend maps \f(CW\*(C`EV_READ\*(C'\fR and \f(CW\*(C`EV_WRITE\*(C'\fR in the same way as |
730 | This backend maps \f(CW\*(C`EV_READ\*(C'\fR and \f(CW\*(C`EV_WRITE\*(C'\fR in the same way as |
625 | \&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
731 | \&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
626 | .ie n .IP """EVBACKEND_ALL""" 4 |
732 | .ie n .IP """EVBACKEND_ALL""" 4 |
627 | .el .IP "\f(CWEVBACKEND_ALL\fR" 4 |
733 | .el .IP "\f(CWEVBACKEND_ALL\fR" 4 |
628 | .IX Item "EVBACKEND_ALL" |
734 | .IX Item "EVBACKEND_ALL" |
629 | Try all backends (even potentially broken ones that wouldn't be tried |
735 | Try all backends (even potentially broken ones that wouldn't be tried |
630 | with \f(CW\*(C`EVFLAG_AUTO\*(C'\fR). Since this is a mask, you can do stuff such as |
736 | with \f(CW\*(C`EVFLAG_AUTO\*(C'\fR). Since this is a mask, you can do stuff such as |
631 | \&\f(CW\*(C`EVBACKEND_ALL & ~EVBACKEND_KQUEUE\*(C'\fR. |
737 | \&\f(CW\*(C`EVBACKEND_ALL & ~EVBACKEND_KQUEUE\*(C'\fR. |
632 | .Sp |
738 | .Sp |
633 | It is definitely not recommended to use this flag. |
739 | It is definitely not recommended to use this flag, use whatever |
|
|
740 | \&\f(CW\*(C`ev_recommended_backends ()\*(C'\fR returns, or simply do not specify a backend |
|
|
741 | at all. |
|
|
742 | .ie n .IP """EVBACKEND_MASK""" 4 |
|
|
743 | .el .IP "\f(CWEVBACKEND_MASK\fR" 4 |
|
|
744 | .IX Item "EVBACKEND_MASK" |
|
|
745 | Not a backend at all, but a mask to select all backend bits from a |
|
|
746 | \&\f(CW\*(C`flags\*(C'\fR value, in case you want to mask out any backends from a flags |
|
|
747 | value (e.g. when modifying the \f(CW\*(C`LIBEV_FLAGS\*(C'\fR environment variable). |
634 | .RE |
748 | .RE |
635 | .RS 4 |
749 | .RS 4 |
636 | .Sp |
750 | .Sp |
637 | If one or more of these are or'ed into the flags value, then only these |
751 | If one or more of the backend flags are or'ed into the flags value, |
638 | backends will be tried (in the reverse order as listed here). If none are |
752 | then only these backends will be tried (in the reverse order as listed |
639 | specified, all backends in \f(CW\*(C`ev_recommended_backends ()\*(C'\fR will be tried. |
753 | here). If none are specified, all backends in \f(CW\*(C`ev_recommended_backends |
640 | .Sp |
754 | ()\*(C'\fR will be tried. |
641 | Example: This is the most typical usage. |
|
|
642 | .Sp |
|
|
643 | .Vb 2 |
|
|
644 | \& if (!ev_default_loop (0)) |
|
|
645 | \& fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?"); |
|
|
646 | .Ve |
|
|
647 | .Sp |
|
|
648 | Example: Restrict libev to the select and poll backends, and do not allow |
|
|
649 | environment settings to be taken into account: |
|
|
650 | .Sp |
|
|
651 | .Vb 1 |
|
|
652 | \& ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV); |
|
|
653 | .Ve |
|
|
654 | .Sp |
|
|
655 | Example: Use whatever libev has to offer, but make sure that kqueue is |
|
|
656 | used if available (warning, breaks stuff, best use only with your own |
|
|
657 | private event loop and only if you know the \s-1OS\s0 supports your types of |
|
|
658 | fds): |
|
|
659 | .Sp |
|
|
660 | .Vb 1 |
|
|
661 | \& ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE); |
|
|
662 | .Ve |
|
|
663 | .RE |
|
|
664 | .IP "struct ev_loop *ev_loop_new (unsigned int flags)" 4 |
|
|
665 | .IX Item "struct ev_loop *ev_loop_new (unsigned int flags)" |
|
|
666 | Similar to \f(CW\*(C`ev_default_loop\*(C'\fR, but always creates a new event loop that is |
|
|
667 | always distinct from the default loop. Unlike the default loop, it cannot |
|
|
668 | handle signal and child watchers, and attempts to do so will be greeted by |
|
|
669 | undefined behaviour (or a failed assertion if assertions are enabled). |
|
|
670 | .Sp |
|
|
671 | Note that this function \fIis\fR thread-safe, and the recommended way to use |
|
|
672 | libev with threads is indeed to create one loop per thread, and using the |
|
|
673 | default loop in the \*(L"main\*(R" or \*(L"initial\*(R" thread. |
|
|
674 | .Sp |
755 | .Sp |
675 | Example: Try to create a event loop that uses epoll and nothing else. |
756 | Example: Try to create a event loop that uses epoll and nothing else. |
676 | .Sp |
757 | .Sp |
677 | .Vb 3 |
758 | .Vb 3 |
678 | \& struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); |
759 | \& struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); |
679 | \& if (!epoller) |
760 | \& if (!epoller) |
680 | \& fatal ("no epoll found here, maybe it hides under your chair"); |
761 | \& fatal ("no epoll found here, maybe it hides under your chair"); |
681 | .Ve |
762 | .Ve |
|
|
763 | .Sp |
|
|
764 | Example: Use whatever libev has to offer, but make sure that kqueue is |
|
|
765 | used if available. |
|
|
766 | .Sp |
|
|
767 | .Vb 1 |
|
|
768 | \& struct ev_loop *loop = ev_loop_new (ev_recommended_backends () | EVBACKEND_KQUEUE); |
|
|
769 | .Ve |
|
|
770 | .RE |
682 | .IP "ev_default_destroy ()" 4 |
771 | .IP "ev_loop_destroy (loop)" 4 |
683 | .IX Item "ev_default_destroy ()" |
772 | .IX Item "ev_loop_destroy (loop)" |
684 | Destroys the default loop again (frees all memory and kernel state |
773 | Destroys an event loop object (frees all memory and kernel state |
685 | etc.). None of the active event watchers will be stopped in the normal |
774 | etc.). None of the active event watchers will be stopped in the normal |
686 | sense, so e.g. \f(CW\*(C`ev_is_active\*(C'\fR might still return true. It is your |
775 | sense, so e.g. \f(CW\*(C`ev_is_active\*(C'\fR might still return true. It is your |
687 | responsibility to either stop all watchers cleanly yourself \fIbefore\fR |
776 | responsibility to either stop all watchers cleanly yourself \fIbefore\fR |
688 | calling this function, or cope with the fact afterwards (which is usually |
777 | calling this function, or cope with the fact afterwards (which is usually |
689 | the easiest thing, you can just ignore the watchers and/or \f(CW\*(C`free ()\*(C'\fR them |
778 | the easiest thing, you can just ignore the watchers and/or \f(CW\*(C`free ()\*(C'\fR them |
… | |
… | |
691 | .Sp |
780 | .Sp |
692 | Note that certain global state, such as signal state (and installed signal |
781 | Note that certain global state, such as signal state (and installed signal |
693 | handlers), will not be freed by this function, and related watchers (such |
782 | handlers), will not be freed by this function, and related watchers (such |
694 | as signal and child watchers) would need to be stopped manually. |
783 | as signal and child watchers) would need to be stopped manually. |
695 | .Sp |
784 | .Sp |
696 | In general it is not advisable to call this function except in the |
785 | This function is normally used on loop objects allocated by |
697 | rare occasion where you really need to free e.g. the signal handling |
786 | \&\f(CW\*(C`ev_loop_new\*(C'\fR, but it can also be used on the default loop returned by |
698 | pipe fds. If you need dynamically allocated loops it is better to use |
787 | \&\f(CW\*(C`ev_default_loop\*(C'\fR, in which case it is not thread-safe. |
699 | \&\f(CW\*(C`ev_loop_new\*(C'\fR and \f(CW\*(C`ev_loop_destroy\*(C'\fR). |
|
|
700 | .IP "ev_loop_destroy (loop)" 4 |
|
|
701 | .IX Item "ev_loop_destroy (loop)" |
|
|
702 | Like \f(CW\*(C`ev_default_destroy\*(C'\fR, but destroys an event loop created by an |
|
|
703 | earlier call to \f(CW\*(C`ev_loop_new\*(C'\fR. |
|
|
704 | .IP "ev_default_fork ()" 4 |
|
|
705 | .IX Item "ev_default_fork ()" |
|
|
706 | This function sets a flag that causes subsequent \f(CW\*(C`ev_loop\*(C'\fR iterations |
|
|
707 | to reinitialise the kernel state for backends that have one. Despite the |
|
|
708 | name, you can call it anytime, but it makes most sense after forking, in |
|
|
709 | the child process (or both child and parent, but that again makes little |
|
|
710 | sense). You \fImust\fR call it in the child before using any of the libev |
|
|
711 | functions, and it will only take effect at the next \f(CW\*(C`ev_loop\*(C'\fR iteration. |
|
|
712 | .Sp |
788 | .Sp |
713 | On the other hand, you only need to call this function in the child |
789 | Note that it is not advisable to call this function on the default loop |
714 | process if and only if you want to use the event library in the child. If |
790 | except in the rare occasion where you really need to free its resources. |
715 | you just fork+exec, you don't have to call it at all. |
791 | If you need dynamically allocated loops it is better to use \f(CW\*(C`ev_loop_new\*(C'\fR |
716 | .Sp |
792 | and \f(CW\*(C`ev_loop_destroy\*(C'\fR. |
717 | The function itself is quite fast and it's usually not a problem to call |
|
|
718 | it just in case after a fork. To make this easy, the function will fit in |
|
|
719 | quite nicely into a call to \f(CW\*(C`pthread_atfork\*(C'\fR: |
|
|
720 | .Sp |
|
|
721 | .Vb 1 |
|
|
722 | \& pthread_atfork (0, 0, ev_default_fork); |
|
|
723 | .Ve |
|
|
724 | .IP "ev_loop_fork (loop)" 4 |
793 | .IP "ev_loop_fork (loop)" 4 |
725 | .IX Item "ev_loop_fork (loop)" |
794 | .IX Item "ev_loop_fork (loop)" |
726 | Like \f(CW\*(C`ev_default_fork\*(C'\fR, but acts on an event loop created by |
795 | This function sets a flag that causes subsequent \f(CW\*(C`ev_run\*(C'\fR iterations to |
727 | \&\f(CW\*(C`ev_loop_new\*(C'\fR. Yes, you have to call this on every allocated event loop |
796 | reinitialise the kernel state for backends that have one. Despite the |
728 | after fork that you want to re-use in the child, and how you do this is |
797 | name, you can call it anytime, but it makes most sense after forking, in |
729 | entirely your own problem. |
798 | the child process. You \fImust\fR call it (or use \f(CW\*(C`EVFLAG_FORKCHECK\*(C'\fR) in the |
|
|
799 | child before resuming or calling \f(CW\*(C`ev_run\*(C'\fR. |
|
|
800 | .Sp |
|
|
801 | Again, you \fIhave\fR to call it on \fIany\fR loop that you want to re-use after |
|
|
802 | a fork, \fIeven if you do not plan to use the loop in the parent\fR. This is |
|
|
803 | because some kernel interfaces *cough* \fIkqueue\fR *cough* do funny things |
|
|
804 | during fork. |
|
|
805 | .Sp |
|
|
806 | On the other hand, you only need to call this function in the child |
|
|
807 | process if and only if you want to use the event loop in the child. If |
|
|
808 | you just fork+exec or create a new loop in the child, you don't have to |
|
|
809 | call it at all (in fact, \f(CW\*(C`epoll\*(C'\fR is so badly broken that it makes a |
|
|
810 | difference, but libev will usually detect this case on its own and do a |
|
|
811 | costly reset of the backend). |
|
|
812 | .Sp |
|
|
813 | The function itself is quite fast and it's usually not a problem to call |
|
|
814 | it just in case after a fork. |
|
|
815 | .Sp |
|
|
816 | Example: Automate calling \f(CW\*(C`ev_loop_fork\*(C'\fR on the default loop when |
|
|
817 | using pthreads. |
|
|
818 | .Sp |
|
|
819 | .Vb 5 |
|
|
820 | \& static void |
|
|
821 | \& post_fork_child (void) |
|
|
822 | \& { |
|
|
823 | \& ev_loop_fork (EV_DEFAULT); |
|
|
824 | \& } |
|
|
825 | \& |
|
|
826 | \& ... |
|
|
827 | \& pthread_atfork (0, 0, post_fork_child); |
|
|
828 | .Ve |
730 | .IP "int ev_is_default_loop (loop)" 4 |
829 | .IP "int ev_is_default_loop (loop)" 4 |
731 | .IX Item "int ev_is_default_loop (loop)" |
830 | .IX Item "int ev_is_default_loop (loop)" |
732 | Returns true when the given loop is, in fact, the default loop, and false |
831 | Returns true when the given loop is, in fact, the default loop, and false |
733 | otherwise. |
832 | otherwise. |
734 | .IP "unsigned int ev_loop_count (loop)" 4 |
833 | .IP "unsigned int ev_iteration (loop)" 4 |
735 | .IX Item "unsigned int ev_loop_count (loop)" |
834 | .IX Item "unsigned int ev_iteration (loop)" |
736 | Returns the count of loop iterations for the loop, which is identical to |
835 | Returns the current iteration count for the event loop, which is identical |
737 | the number of times libev did poll for new events. It starts at \f(CW0\fR and |
836 | to the number of times libev did poll for new events. It starts at \f(CW0\fR |
738 | happily wraps around with enough iterations. |
837 | and happily wraps around with enough iterations. |
739 | .Sp |
838 | .Sp |
740 | This value can sometimes be useful as a generation counter of sorts (it |
839 | This value can sometimes be useful as a generation counter of sorts (it |
741 | \&\*(L"ticks\*(R" the number of loop iterations), as it roughly corresponds with |
840 | \&\*(L"ticks\*(R" the number of loop iterations), as it roughly corresponds with |
742 | \&\f(CW\*(C`ev_prepare\*(C'\fR and \f(CW\*(C`ev_check\*(C'\fR calls. |
841 | \&\f(CW\*(C`ev_prepare\*(C'\fR and \f(CW\*(C`ev_check\*(C'\fR calls \- and is incremented between the |
|
|
842 | prepare and check phases. |
|
|
843 | .IP "unsigned int ev_depth (loop)" 4 |
|
|
844 | .IX Item "unsigned int ev_depth (loop)" |
|
|
845 | Returns the number of times \f(CW\*(C`ev_run\*(C'\fR was entered minus the number of |
|
|
846 | times \f(CW\*(C`ev_run\*(C'\fR was exited normally, in other words, the recursion depth. |
|
|
847 | .Sp |
|
|
848 | Outside \f(CW\*(C`ev_run\*(C'\fR, this number is zero. In a callback, this number is |
|
|
849 | \&\f(CW1\fR, unless \f(CW\*(C`ev_run\*(C'\fR was invoked recursively (or from another thread), |
|
|
850 | in which case it is higher. |
|
|
851 | .Sp |
|
|
852 | Leaving \f(CW\*(C`ev_run\*(C'\fR abnormally (setjmp/longjmp, cancelling the thread, |
|
|
853 | throwing an exception etc.), doesn't count as \*(L"exit\*(R" \- consider this |
|
|
854 | as a hint to avoid such ungentleman-like behaviour unless it's really |
|
|
855 | convenient, in which case it is fully supported. |
743 | .IP "unsigned int ev_backend (loop)" 4 |
856 | .IP "unsigned int ev_backend (loop)" 4 |
744 | .IX Item "unsigned int ev_backend (loop)" |
857 | .IX Item "unsigned int ev_backend (loop)" |
745 | Returns one of the \f(CW\*(C`EVBACKEND_*\*(C'\fR flags indicating the event backend in |
858 | Returns one of the \f(CW\*(C`EVBACKEND_*\*(C'\fR flags indicating the event backend in |
746 | use. |
859 | use. |
747 | .IP "ev_tstamp ev_now (loop)" 4 |
860 | .IP "ev_tstamp ev_now (loop)" 4 |
… | |
… | |
753 | event occurring (or more correctly, libev finding out about it). |
866 | event occurring (or more correctly, libev finding out about it). |
754 | .IP "ev_now_update (loop)" 4 |
867 | .IP "ev_now_update (loop)" 4 |
755 | .IX Item "ev_now_update (loop)" |
868 | .IX Item "ev_now_update (loop)" |
756 | Establishes the current time by querying the kernel, updating the time |
869 | Establishes the current time by querying the kernel, updating the time |
757 | returned by \f(CW\*(C`ev_now ()\*(C'\fR in the progress. This is a costly operation and |
870 | returned by \f(CW\*(C`ev_now ()\*(C'\fR in the progress. This is a costly operation and |
758 | is usually done automatically within \f(CW\*(C`ev_loop ()\*(C'\fR. |
871 | is usually done automatically within \f(CW\*(C`ev_run ()\*(C'\fR. |
759 | .Sp |
872 | .Sp |
760 | This function is rarely useful, but when some event callback runs for a |
873 | This function is rarely useful, but when some event callback runs for a |
761 | very long time without entering the event loop, updating libev's idea of |
874 | very long time without entering the event loop, updating libev's idea of |
762 | the current time is a good idea. |
875 | the current time is a good idea. |
763 | .Sp |
876 | .Sp |
764 | See also \*(L"The special problem of time updates\*(R" in the \f(CW\*(C`ev_timer\*(C'\fR section. |
877 | See also \*(L"The special problem of time updates\*(R" in the \f(CW\*(C`ev_timer\*(C'\fR section. |
|
|
878 | .IP "ev_suspend (loop)" 4 |
|
|
879 | .IX Item "ev_suspend (loop)" |
|
|
880 | .PD 0 |
|
|
881 | .IP "ev_resume (loop)" 4 |
|
|
882 | .IX Item "ev_resume (loop)" |
|
|
883 | .PD |
|
|
884 | These two functions suspend and resume an event loop, for use when the |
|
|
885 | loop is not used for a while and timeouts should not be processed. |
|
|
886 | .Sp |
|
|
887 | A typical use case would be an interactive program such as a game: When |
|
|
888 | the user presses \f(CW\*(C`^Z\*(C'\fR to suspend the game and resumes it an hour later it |
|
|
889 | would be best to handle timeouts as if no time had actually passed while |
|
|
890 | the program was suspended. This can be achieved by calling \f(CW\*(C`ev_suspend\*(C'\fR |
|
|
891 | in your \f(CW\*(C`SIGTSTP\*(C'\fR handler, sending yourself a \f(CW\*(C`SIGSTOP\*(C'\fR and calling |
|
|
892 | \&\f(CW\*(C`ev_resume\*(C'\fR directly afterwards to resume timer processing. |
|
|
893 | .Sp |
|
|
894 | Effectively, all \f(CW\*(C`ev_timer\*(C'\fR watchers will be delayed by the time spend |
|
|
895 | 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 |
|
|
896 | will be rescheduled (that is, they will lose any events that would have |
|
|
897 | occurred while suspended). |
|
|
898 | .Sp |
|
|
899 | After calling \f(CW\*(C`ev_suspend\*(C'\fR you \fBmust not\fR call \fIany\fR function on the |
|
|
900 | given loop other than \f(CW\*(C`ev_resume\*(C'\fR, and you \fBmust not\fR call \f(CW\*(C`ev_resume\*(C'\fR |
|
|
901 | without a previous call to \f(CW\*(C`ev_suspend\*(C'\fR. |
|
|
902 | .Sp |
|
|
903 | Calling \f(CW\*(C`ev_suspend\*(C'\fR/\f(CW\*(C`ev_resume\*(C'\fR has the side effect of updating the |
|
|
904 | event loop time (see \f(CW\*(C`ev_now_update\*(C'\fR). |
765 | .IP "ev_loop (loop, int flags)" 4 |
905 | .IP "ev_run (loop, int flags)" 4 |
766 | .IX Item "ev_loop (loop, int flags)" |
906 | .IX Item "ev_run (loop, int flags)" |
767 | Finally, this is it, the event handler. This function usually is called |
907 | Finally, this is it, the event handler. This function usually is called |
768 | after you initialised all your watchers and you want to start handling |
908 | after you have initialised all your watchers and you want to start |
769 | events. |
909 | handling events. It will ask the operating system for any new events, call |
|
|
910 | the watcher callbacks, an then repeat the whole process indefinitely: This |
|
|
911 | is why event loops are called \fIloops\fR. |
770 | .Sp |
912 | .Sp |
771 | If the flags argument is specified as \f(CW0\fR, it will not return until |
913 | If the flags argument is specified as \f(CW0\fR, it will keep handling events |
772 | either no event watchers are active anymore or \f(CW\*(C`ev_unloop\*(C'\fR was called. |
914 | until either no event watchers are active anymore or \f(CW\*(C`ev_break\*(C'\fR was |
|
|
915 | called. |
773 | .Sp |
916 | .Sp |
774 | Please note that an explicit \f(CW\*(C`ev_unloop\*(C'\fR is usually better than |
917 | Please note that an explicit \f(CW\*(C`ev_break\*(C'\fR is usually better than |
775 | relying on all watchers to be stopped when deciding when a program has |
918 | relying on all watchers to be stopped when deciding when a program has |
776 | finished (especially in interactive programs), but having a program |
919 | finished (especially in interactive programs), but having a program |
777 | that automatically loops as long as it has to and no longer by virtue |
920 | that automatically loops as long as it has to and no longer by virtue |
778 | of relying on its watchers stopping correctly, that is truly a thing of |
921 | of relying on its watchers stopping correctly, that is truly a thing of |
779 | beauty. |
922 | beauty. |
780 | .Sp |
923 | .Sp |
|
|
924 | This function is also \fImostly\fR exception-safe \- you can break out of |
|
|
925 | a \f(CW\*(C`ev_run\*(C'\fR call by calling \f(CW\*(C`longjmp\*(C'\fR in a callback, throwing a \*(C+ |
|
|
926 | exception and so on. This does not decrement the \f(CW\*(C`ev_depth\*(C'\fR value, nor |
|
|
927 | will it clear any outstanding \f(CW\*(C`EVBREAK_ONE\*(C'\fR breaks. |
|
|
928 | .Sp |
781 | A flags value of \f(CW\*(C`EVLOOP_NONBLOCK\*(C'\fR will look for new events, will handle |
929 | A flags value of \f(CW\*(C`EVRUN_NOWAIT\*(C'\fR will look for new events, will handle |
782 | those events and any already outstanding ones, but will not block your |
930 | those events and any already outstanding ones, but will not wait and |
783 | process in case there are no events and will return after one iteration of |
931 | block your process in case there are no events and will return after one |
784 | the loop. |
932 | iteration of the loop. This is sometimes useful to poll and handle new |
|
|
933 | events while doing lengthy calculations, to keep the program responsive. |
785 | .Sp |
934 | .Sp |
786 | A flags value of \f(CW\*(C`EVLOOP_ONESHOT\*(C'\fR will look for new events (waiting if |
935 | A flags value of \f(CW\*(C`EVRUN_ONCE\*(C'\fR will look for new events (waiting if |
787 | necessary) and will handle those and any already outstanding ones. It |
936 | necessary) and will handle those and any already outstanding ones. It |
788 | will block your process until at least one new event arrives (which could |
937 | will block your process until at least one new event arrives (which could |
789 | be an event internal to libev itself, so there is no guarantee that a |
938 | be an event internal to libev itself, so there is no guarantee that a |
790 | user-registered callback will be called), and will return after one |
939 | user-registered callback will be called), and will return after one |
791 | iteration of the loop. |
940 | iteration of the loop. |
792 | .Sp |
941 | .Sp |
793 | This is useful if you are waiting for some external event in conjunction |
942 | This is useful if you are waiting for some external event in conjunction |
794 | with something not expressible using other libev watchers (i.e. "roll your |
943 | with something not expressible using other libev watchers (i.e. "roll your |
795 | 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 |
944 | 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 |
796 | usually a better approach for this kind of thing. |
945 | usually a better approach for this kind of thing. |
797 | .Sp |
946 | .Sp |
798 | Here are the gory details of what \f(CW\*(C`ev_loop\*(C'\fR does: |
947 | Here are the gory details of what \f(CW\*(C`ev_run\*(C'\fR does: |
799 | .Sp |
948 | .Sp |
800 | .Vb 10 |
949 | .Vb 10 |
|
|
950 | \& \- Increment loop depth. |
|
|
951 | \& \- Reset the ev_break status. |
801 | \& \- Before the first iteration, call any pending watchers. |
952 | \& \- Before the first iteration, call any pending watchers. |
|
|
953 | \& LOOP: |
802 | \& * If EVFLAG_FORKCHECK was used, check for a fork. |
954 | \& \- If EVFLAG_FORKCHECK was used, check for a fork. |
803 | \& \- If a fork was detected (by any means), queue and call all fork watchers. |
955 | \& \- If a fork was detected (by any means), queue and call all fork watchers. |
804 | \& \- Queue and call all prepare watchers. |
956 | \& \- Queue and call all prepare watchers. |
|
|
957 | \& \- If ev_break was called, goto FINISH. |
805 | \& \- If we have been forked, detach and recreate the kernel state |
958 | \& \- If we have been forked, detach and recreate the kernel state |
806 | \& as to not disturb the other process. |
959 | \& as to not disturb the other process. |
807 | \& \- Update the kernel state with all outstanding changes. |
960 | \& \- Update the kernel state with all outstanding changes. |
808 | \& \- Update the "event loop time" (ev_now ()). |
961 | \& \- Update the "event loop time" (ev_now ()). |
809 | \& \- Calculate for how long to sleep or block, if at all |
962 | \& \- Calculate for how long to sleep or block, if at all |
810 | \& (active idle watchers, EVLOOP_NONBLOCK or not having |
963 | \& (active idle watchers, EVRUN_NOWAIT or not having |
811 | \& any active watchers at all will result in not sleeping). |
964 | \& any active watchers at all will result in not sleeping). |
812 | \& \- Sleep if the I/O and timer collect interval say so. |
965 | \& \- Sleep if the I/O and timer collect interval say so. |
|
|
966 | \& \- Increment loop iteration counter. |
813 | \& \- Block the process, waiting for any events. |
967 | \& \- Block the process, waiting for any events. |
814 | \& \- Queue all outstanding I/O (fd) events. |
968 | \& \- Queue all outstanding I/O (fd) events. |
815 | \& \- Update the "event loop time" (ev_now ()), and do time jump adjustments. |
969 | \& \- Update the "event loop time" (ev_now ()), and do time jump adjustments. |
816 | \& \- Queue all expired timers. |
970 | \& \- Queue all expired timers. |
817 | \& \- Queue all expired periodics. |
971 | \& \- Queue all expired periodics. |
818 | \& \- Unless any events are pending now, queue all idle watchers. |
972 | \& \- Queue all idle watchers with priority higher than that of pending events. |
819 | \& \- Queue all check watchers. |
973 | \& \- Queue all check watchers. |
820 | \& \- Call all queued watchers in reverse order (i.e. check watchers first). |
974 | \& \- Call all queued watchers in reverse order (i.e. check watchers first). |
821 | \& Signals and child watchers are implemented as I/O watchers, and will |
975 | \& Signals and child watchers are implemented as I/O watchers, and will |
822 | \& be handled here by queueing them when their watcher gets executed. |
976 | \& be handled here by queueing them when their watcher gets executed. |
823 | \& \- If ev_unloop has been called, or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
977 | \& \- If ev_break has been called, or EVRUN_ONCE or EVRUN_NOWAIT |
824 | \& were used, or there are no active watchers, return, otherwise |
978 | \& were used, or there are no active watchers, goto FINISH, otherwise |
825 | \& continue with step *. |
979 | \& continue with step LOOP. |
|
|
980 | \& FINISH: |
|
|
981 | \& \- Reset the ev_break status iff it was EVBREAK_ONE. |
|
|
982 | \& \- Decrement the loop depth. |
|
|
983 | \& \- Return. |
826 | .Ve |
984 | .Ve |
827 | .Sp |
985 | .Sp |
828 | Example: Queue some jobs and then loop until no events are outstanding |
986 | Example: Queue some jobs and then loop until no events are outstanding |
829 | anymore. |
987 | anymore. |
830 | .Sp |
988 | .Sp |
831 | .Vb 4 |
989 | .Vb 4 |
832 | \& ... queue jobs here, make sure they register event watchers as long |
990 | \& ... queue jobs here, make sure they register event watchers as long |
833 | \& ... as they still have work to do (even an idle watcher will do..) |
991 | \& ... as they still have work to do (even an idle watcher will do..) |
834 | \& ev_loop (my_loop, 0); |
992 | \& ev_run (my_loop, 0); |
835 | \& ... jobs done or somebody called unloop. yeah! |
993 | \& ... jobs done or somebody called break. yeah! |
836 | .Ve |
994 | .Ve |
837 | .IP "ev_unloop (loop, how)" 4 |
995 | .IP "ev_break (loop, how)" 4 |
838 | .IX Item "ev_unloop (loop, how)" |
996 | .IX Item "ev_break (loop, how)" |
839 | Can be used to make a call to \f(CW\*(C`ev_loop\*(C'\fR return early (but only after it |
997 | Can be used to make a call to \f(CW\*(C`ev_run\*(C'\fR return early (but only after it |
840 | has processed all outstanding events). The \f(CW\*(C`how\*(C'\fR argument must be either |
998 | has processed all outstanding events). The \f(CW\*(C`how\*(C'\fR argument must be either |
841 | \&\f(CW\*(C`EVUNLOOP_ONE\*(C'\fR, which will make the innermost \f(CW\*(C`ev_loop\*(C'\fR call return, or |
999 | \&\f(CW\*(C`EVBREAK_ONE\*(C'\fR, which will make the innermost \f(CW\*(C`ev_run\*(C'\fR call return, or |
842 | \&\f(CW\*(C`EVUNLOOP_ALL\*(C'\fR, which will make all nested \f(CW\*(C`ev_loop\*(C'\fR calls return. |
1000 | \&\f(CW\*(C`EVBREAK_ALL\*(C'\fR, which will make all nested \f(CW\*(C`ev_run\*(C'\fR calls return. |
843 | .Sp |
1001 | .Sp |
844 | This \*(L"unloop state\*(R" will be cleared when entering \f(CW\*(C`ev_loop\*(C'\fR again. |
1002 | This \*(L"break state\*(R" will be cleared on the next call to \f(CW\*(C`ev_run\*(C'\fR. |
845 | .Sp |
1003 | .Sp |
846 | It is safe to call \f(CW\*(C`ev_unloop\*(C'\fR from otuside any \f(CW\*(C`ev_loop\*(C'\fR calls. |
1004 | 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 |
|
|
1005 | which case it will have no effect. |
847 | .IP "ev_ref (loop)" 4 |
1006 | .IP "ev_ref (loop)" 4 |
848 | .IX Item "ev_ref (loop)" |
1007 | .IX Item "ev_ref (loop)" |
849 | .PD 0 |
1008 | .PD 0 |
850 | .IP "ev_unref (loop)" 4 |
1009 | .IP "ev_unref (loop)" 4 |
851 | .IX Item "ev_unref (loop)" |
1010 | .IX Item "ev_unref (loop)" |
852 | .PD |
1011 | .PD |
853 | Ref/unref can be used to add or remove a reference count on the event |
1012 | Ref/unref can be used to add or remove a reference count on the event |
854 | loop: Every watcher keeps one reference, and as long as the reference |
1013 | loop: Every watcher keeps one reference, and as long as the reference |
855 | count is nonzero, \f(CW\*(C`ev_loop\*(C'\fR will not return on its own. |
1014 | count is nonzero, \f(CW\*(C`ev_run\*(C'\fR will not return on its own. |
856 | .Sp |
1015 | .Sp |
857 | If you have a watcher you never unregister that should not keep \f(CW\*(C`ev_loop\*(C'\fR |
1016 | This is useful when you have a watcher that you never intend to |
858 | from returning, call \fIev_unref()\fR after starting, and \fIev_ref()\fR before |
1017 | unregister, but that nevertheless should not keep \f(CW\*(C`ev_run\*(C'\fR from |
|
|
1018 | returning. In such a case, call \f(CW\*(C`ev_unref\*(C'\fR after starting, and \f(CW\*(C`ev_ref\*(C'\fR |
859 | stopping it. |
1019 | before stopping it. |
860 | .Sp |
1020 | .Sp |
861 | As an example, libev itself uses this for its internal signal pipe: It is |
1021 | As an example, libev itself uses this for its internal signal pipe: It |
862 | not visible to the libev user and should not keep \f(CW\*(C`ev_loop\*(C'\fR from exiting |
1022 | is not visible to the libev user and should not keep \f(CW\*(C`ev_run\*(C'\fR from |
863 | if no event watchers registered by it are active. It is also an excellent |
1023 | exiting if no event watchers registered by it are active. It is also an |
864 | way to do this for generic recurring timers or from within third-party |
1024 | excellent way to do this for generic recurring timers or from within |
865 | libraries. Just remember to \fIunref after start\fR and \fIref before stop\fR |
1025 | third-party libraries. Just remember to \fIunref after start\fR and \fIref |
866 | (but only if the watcher wasn't active before, or was active before, |
1026 | before stop\fR (but only if the watcher wasn't active before, or was active |
867 | respectively). |
1027 | before, respectively. Note also that libev might stop watchers itself |
|
|
1028 | (e.g. non-repeating timers) in which case you have to \f(CW\*(C`ev_ref\*(C'\fR |
|
|
1029 | in the callback). |
868 | .Sp |
1030 | .Sp |
869 | Example: Create a signal watcher, but keep it from keeping \f(CW\*(C`ev_loop\*(C'\fR |
1031 | Example: Create a signal watcher, but keep it from keeping \f(CW\*(C`ev_run\*(C'\fR |
870 | running when nothing else is active. |
1032 | running when nothing else is active. |
871 | .Sp |
1033 | .Sp |
872 | .Vb 4 |
1034 | .Vb 4 |
873 | \& ev_signal exitsig; |
1035 | \& ev_signal exitsig; |
874 | \& ev_signal_init (&exitsig, sig_cb, SIGINT); |
1036 | \& ev_signal_init (&exitsig, sig_cb, SIGINT); |
875 | \& ev_signal_start (loop, &exitsig); |
1037 | \& ev_signal_start (loop, &exitsig); |
876 | \& evf_unref (loop); |
1038 | \& ev_unref (loop); |
877 | .Ve |
1039 | .Ve |
878 | .Sp |
1040 | .Sp |
879 | Example: For some weird reason, unregister the above signal handler again. |
1041 | Example: For some weird reason, unregister the above signal handler again. |
880 | .Sp |
1042 | .Sp |
881 | .Vb 2 |
1043 | .Vb 2 |
… | |
… | |
906 | .Sp |
1068 | .Sp |
907 | By setting a higher \fIio collect interval\fR you allow libev to spend more |
1069 | By setting a higher \fIio collect interval\fR you allow libev to spend more |
908 | time collecting I/O events, so you can handle more events per iteration, |
1070 | time collecting I/O events, so you can handle more events per iteration, |
909 | at the cost of increasing latency. Timeouts (both \f(CW\*(C`ev_periodic\*(C'\fR and |
1071 | at the cost of increasing latency. Timeouts (both \f(CW\*(C`ev_periodic\*(C'\fR and |
910 | \&\f(CW\*(C`ev_timer\*(C'\fR) will be not affected. Setting this to a non-null value will |
1072 | \&\f(CW\*(C`ev_timer\*(C'\fR) will be not affected. Setting this to a non-null value will |
911 | introduce an additional \f(CW\*(C`ev_sleep ()\*(C'\fR call into most loop iterations. |
1073 | introduce an additional \f(CW\*(C`ev_sleep ()\*(C'\fR call into most loop iterations. The |
|
|
1074 | sleep time ensures that libev will not poll for I/O events more often then |
|
|
1075 | once per this interval, on average. |
912 | .Sp |
1076 | .Sp |
913 | Likewise, by setting a higher \fItimeout collect interval\fR you allow libev |
1077 | Likewise, by setting a higher \fItimeout collect interval\fR you allow libev |
914 | to spend more time collecting timeouts, at the expense of increased |
1078 | to spend more time collecting timeouts, at the expense of increased |
915 | latency/jitter/inexactness (the watcher callback will be called |
1079 | latency/jitter/inexactness (the watcher callback will be called |
916 | later). \f(CW\*(C`ev_io\*(C'\fR watchers will not be affected. Setting this to a non-null |
1080 | later). \f(CW\*(C`ev_io\*(C'\fR watchers will not be affected. Setting this to a non-null |
… | |
… | |
918 | .Sp |
1082 | .Sp |
919 | Many (busy) programs can usually benefit by setting the I/O collect |
1083 | Many (busy) programs can usually benefit by setting the I/O collect |
920 | interval to a value near \f(CW0.1\fR or so, which is often enough for |
1084 | interval to a value near \f(CW0.1\fR or so, which is often enough for |
921 | interactive servers (of course not for games), likewise for timeouts. It |
1085 | interactive servers (of course not for games), likewise for timeouts. It |
922 | usually doesn't make much sense to set it to a lower value than \f(CW0.01\fR, |
1086 | usually doesn't make much sense to set it to a lower value than \f(CW0.01\fR, |
923 | as this approaches the timing granularity of most systems. |
1087 | as this approaches the timing granularity of most systems. Note that if |
|
|
1088 | you do transactions with the outside world and you can't increase the |
|
|
1089 | parallelity, then this setting will limit your transaction rate (if you |
|
|
1090 | need to poll once per transaction and the I/O collect interval is 0.01, |
|
|
1091 | then you can't do more than 100 transactions per second). |
924 | .Sp |
1092 | .Sp |
925 | Setting the \fItimeout collect interval\fR can improve the opportunity for |
1093 | Setting the \fItimeout collect interval\fR can improve the opportunity for |
926 | saving power, as the program will \*(L"bundle\*(R" timer callback invocations that |
1094 | saving power, as the program will \*(L"bundle\*(R" timer callback invocations that |
927 | are \*(L"near\*(R" in time together, by delaying some, thus reducing the number of |
1095 | are \*(L"near\*(R" in time together, by delaying some, thus reducing the number of |
928 | times the process sleeps and wakes up again. Another useful technique to |
1096 | times the process sleeps and wakes up again. Another useful technique to |
929 | reduce iterations/wake\-ups is to use \f(CW\*(C`ev_periodic\*(C'\fR watchers and make sure |
1097 | reduce iterations/wake\-ups is to use \f(CW\*(C`ev_periodic\*(C'\fR watchers and make sure |
930 | they fire on, say, one-second boundaries only. |
1098 | they fire on, say, one-second boundaries only. |
|
|
1099 | .Sp |
|
|
1100 | Example: we only need 0.1s timeout granularity, and we wish not to poll |
|
|
1101 | more often than 100 times per second: |
|
|
1102 | .Sp |
|
|
1103 | .Vb 2 |
|
|
1104 | \& ev_set_timeout_collect_interval (EV_DEFAULT_UC_ 0.1); |
|
|
1105 | \& ev_set_io_collect_interval (EV_DEFAULT_UC_ 0.01); |
|
|
1106 | .Ve |
|
|
1107 | .IP "ev_invoke_pending (loop)" 4 |
|
|
1108 | .IX Item "ev_invoke_pending (loop)" |
|
|
1109 | This call will simply invoke all pending watchers while resetting their |
|
|
1110 | pending state. Normally, \f(CW\*(C`ev_run\*(C'\fR does this automatically when required, |
|
|
1111 | but when overriding the invoke callback this call comes handy. This |
|
|
1112 | function can be invoked from a watcher \- this can be useful for example |
|
|
1113 | when you want to do some lengthy calculation and want to pass further |
|
|
1114 | event handling to another thread (you still have to make sure only one |
|
|
1115 | thread executes within \f(CW\*(C`ev_invoke_pending\*(C'\fR or \f(CW\*(C`ev_run\*(C'\fR of course). |
|
|
1116 | .IP "int ev_pending_count (loop)" 4 |
|
|
1117 | .IX Item "int ev_pending_count (loop)" |
|
|
1118 | Returns the number of pending watchers \- zero indicates that no watchers |
|
|
1119 | are pending. |
|
|
1120 | .IP "ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(\s-1EV_P\s0))" 4 |
|
|
1121 | .IX Item "ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(EV_P))" |
|
|
1122 | This overrides the invoke pending functionality of the loop: Instead of |
|
|
1123 | invoking all pending watchers when there are any, \f(CW\*(C`ev_run\*(C'\fR will call |
|
|
1124 | this callback instead. This is useful, for example, when you want to |
|
|
1125 | invoke the actual watchers inside another context (another thread etc.). |
|
|
1126 | .Sp |
|
|
1127 | If you want to reset the callback, use \f(CW\*(C`ev_invoke_pending\*(C'\fR as new |
|
|
1128 | callback. |
|
|
1129 | .IP "ev_set_loop_release_cb (loop, void (*release)(\s-1EV_P\s0), void (*acquire)(\s-1EV_P\s0))" 4 |
|
|
1130 | .IX Item "ev_set_loop_release_cb (loop, void (*release)(EV_P), void (*acquire)(EV_P))" |
|
|
1131 | Sometimes you want to share the same loop between multiple threads. This |
|
|
1132 | can be done relatively simply by putting mutex_lock/unlock calls around |
|
|
1133 | each call to a libev function. |
|
|
1134 | .Sp |
|
|
1135 | However, \f(CW\*(C`ev_run\*(C'\fR can run an indefinite time, so it is not feasible |
|
|
1136 | to wait for it to return. One way around this is to wake up the event |
|
|
1137 | loop via \f(CW\*(C`ev_break\*(C'\fR and \f(CW\*(C`av_async_send\*(C'\fR, another way is to set these |
|
|
1138 | \&\fIrelease\fR and \fIacquire\fR callbacks on the loop. |
|
|
1139 | .Sp |
|
|
1140 | When set, then \f(CW\*(C`release\*(C'\fR will be called just before the thread is |
|
|
1141 | suspended waiting for new events, and \f(CW\*(C`acquire\*(C'\fR is called just |
|
|
1142 | afterwards. |
|
|
1143 | .Sp |
|
|
1144 | Ideally, \f(CW\*(C`release\*(C'\fR will just call your mutex_unlock function, and |
|
|
1145 | \&\f(CW\*(C`acquire\*(C'\fR will just call the mutex_lock function again. |
|
|
1146 | .Sp |
|
|
1147 | While event loop modifications are allowed between invocations of |
|
|
1148 | \&\f(CW\*(C`release\*(C'\fR and \f(CW\*(C`acquire\*(C'\fR (that's their only purpose after all), no |
|
|
1149 | modifications done will affect the event loop, i.e. adding watchers will |
|
|
1150 | have no effect on the set of file descriptors being watched, or the time |
|
|
1151 | 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 |
|
|
1152 | to take note of any changes you made. |
|
|
1153 | .Sp |
|
|
1154 | In theory, threads executing \f(CW\*(C`ev_run\*(C'\fR will be async-cancel safe between |
|
|
1155 | invocations of \f(CW\*(C`release\*(C'\fR and \f(CW\*(C`acquire\*(C'\fR. |
|
|
1156 | .Sp |
|
|
1157 | See also the locking example in the \f(CW\*(C`THREADS\*(C'\fR section later in this |
|
|
1158 | document. |
|
|
1159 | .IP "ev_set_userdata (loop, void *data)" 4 |
|
|
1160 | .IX Item "ev_set_userdata (loop, void *data)" |
|
|
1161 | .PD 0 |
|
|
1162 | .IP "void *ev_userdata (loop)" 4 |
|
|
1163 | .IX Item "void *ev_userdata (loop)" |
|
|
1164 | .PD |
|
|
1165 | Set and retrieve a single \f(CW\*(C`void *\*(C'\fR associated with a loop. When |
|
|
1166 | \&\f(CW\*(C`ev_set_userdata\*(C'\fR has never been called, then \f(CW\*(C`ev_userdata\*(C'\fR returns |
|
|
1167 | \&\f(CW0\fR. |
|
|
1168 | .Sp |
|
|
1169 | These two functions can be used to associate arbitrary data with a loop, |
|
|
1170 | and are intended solely for the \f(CW\*(C`invoke_pending_cb\*(C'\fR, \f(CW\*(C`release\*(C'\fR and |
|
|
1171 | \&\f(CW\*(C`acquire\*(C'\fR callbacks described above, but of course can be (ab\-)used for |
|
|
1172 | any other purpose as well. |
931 | .IP "ev_loop_verify (loop)" 4 |
1173 | .IP "ev_verify (loop)" 4 |
932 | .IX Item "ev_loop_verify (loop)" |
1174 | .IX Item "ev_verify (loop)" |
933 | This function only does something when \f(CW\*(C`EV_VERIFY\*(C'\fR support has been |
1175 | This function only does something when \f(CW\*(C`EV_VERIFY\*(C'\fR support has been |
934 | compiled in, which is the default for non-minimal builds. It tries to go |
1176 | compiled in, which is the default for non-minimal builds. It tries to go |
935 | through all internal structures and checks them for validity. If anything |
1177 | through all internal structures and checks them for validity. If anything |
936 | is found to be inconsistent, it will print an error message to standard |
1178 | is found to be inconsistent, it will print an error message to standard |
937 | error and call \f(CW\*(C`abort ()\*(C'\fR. |
1179 | error and call \f(CW\*(C`abort ()\*(C'\fR. |
… | |
… | |
943 | .IX Header "ANATOMY OF A WATCHER" |
1185 | .IX Header "ANATOMY OF A WATCHER" |
944 | In the following description, uppercase \f(CW\*(C`TYPE\*(C'\fR in names stands for the |
1186 | In the following description, uppercase \f(CW\*(C`TYPE\*(C'\fR in names stands for the |
945 | watcher type, e.g. \f(CW\*(C`ev_TYPE_start\*(C'\fR can mean \f(CW\*(C`ev_timer_start\*(C'\fR for timer |
1187 | watcher type, e.g. \f(CW\*(C`ev_TYPE_start\*(C'\fR can mean \f(CW\*(C`ev_timer_start\*(C'\fR for timer |
946 | watchers and \f(CW\*(C`ev_io_start\*(C'\fR for I/O watchers. |
1188 | watchers and \f(CW\*(C`ev_io_start\*(C'\fR for I/O watchers. |
947 | .PP |
1189 | .PP |
948 | A watcher is a structure that you create and register to record your |
1190 | A watcher is an opaque structure that you allocate and register to record |
949 | interest in some event. For instance, if you want to wait for \s-1STDIN\s0 to |
1191 | your interest in some event. To make a concrete example, imagine you want |
950 | become readable, you would create an \f(CW\*(C`ev_io\*(C'\fR watcher for that: |
1192 | to wait for \s-1STDIN\s0 to become readable, you would create an \f(CW\*(C`ev_io\*(C'\fR watcher |
|
|
1193 | for that: |
951 | .PP |
1194 | .PP |
952 | .Vb 5 |
1195 | .Vb 5 |
953 | \& static void my_cb (struct ev_loop *loop, ev_io *w, int revents) |
1196 | \& static void my_cb (struct ev_loop *loop, ev_io *w, int revents) |
954 | \& { |
1197 | \& { |
955 | \& ev_io_stop (w); |
1198 | \& ev_io_stop (w); |
956 | \& ev_unloop (loop, EVUNLOOP_ALL); |
1199 | \& ev_break (loop, EVBREAK_ALL); |
957 | \& } |
1200 | \& } |
958 | \& |
1201 | \& |
959 | \& struct ev_loop *loop = ev_default_loop (0); |
1202 | \& struct ev_loop *loop = ev_default_loop (0); |
960 | \& |
1203 | \& |
961 | \& ev_io stdin_watcher; |
1204 | \& ev_io stdin_watcher; |
962 | \& |
1205 | \& |
963 | \& ev_init (&stdin_watcher, my_cb); |
1206 | \& ev_init (&stdin_watcher, my_cb); |
964 | \& ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ); |
1207 | \& ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ); |
965 | \& ev_io_start (loop, &stdin_watcher); |
1208 | \& ev_io_start (loop, &stdin_watcher); |
966 | \& |
1209 | \& |
967 | \& ev_loop (loop, 0); |
1210 | \& ev_run (loop, 0); |
968 | .Ve |
1211 | .Ve |
969 | .PP |
1212 | .PP |
970 | As you can see, you are responsible for allocating the memory for your |
1213 | As you can see, you are responsible for allocating the memory for your |
971 | watcher structures (and it is \fIusually\fR a bad idea to do this on the |
1214 | watcher structures (and it is \fIusually\fR a bad idea to do this on the |
972 | stack). |
1215 | stack). |
973 | .PP |
1216 | .PP |
974 | Each watcher has an associated watcher structure (called \f(CW\*(C`struct ev_TYPE\*(C'\fR |
1217 | Each watcher has an associated watcher structure (called \f(CW\*(C`struct ev_TYPE\*(C'\fR |
975 | or simply \f(CW\*(C`ev_TYPE\*(C'\fR, as typedefs are provided for all watcher structs). |
1218 | or simply \f(CW\*(C`ev_TYPE\*(C'\fR, as typedefs are provided for all watcher structs). |
976 | .PP |
1219 | .PP |
977 | Each watcher structure must be initialised by a call to \f(CW\*(C`ev_init |
1220 | Each watcher structure must be initialised by a call to \f(CW\*(C`ev_init (watcher |
978 | (watcher *, callback)\*(C'\fR, which expects a callback to be provided. This |
1221 | *, callback)\*(C'\fR, which expects a callback to be provided. This callback is |
979 | callback gets invoked each time the event occurs (or, in the case of I/O |
1222 | invoked each time the event occurs (or, in the case of I/O watchers, each |
980 | watchers, each time the event loop detects that the file descriptor given |
1223 | time the event loop detects that the file descriptor given is readable |
981 | is readable and/or writable). |
1224 | and/or writable). |
982 | .PP |
1225 | .PP |
983 | Each watcher type further has its own \f(CW\*(C`ev_TYPE_set (watcher *, ...)\*(C'\fR |
1226 | Each watcher type further has its own \f(CW\*(C`ev_TYPE_set (watcher *, ...)\*(C'\fR |
984 | macro to configure it, with arguments specific to the watcher type. There |
1227 | macro to configure it, with arguments specific to the watcher type. There |
985 | is also a macro to combine initialisation and setting in one call: \f(CW\*(C`ev_TYPE_init (watcher *, callback, ...)\*(C'\fR. |
1228 | is also a macro to combine initialisation and setting in one call: \f(CW\*(C`ev_TYPE_init (watcher *, callback, ...)\*(C'\fR. |
986 | .PP |
1229 | .PP |
… | |
… | |
1008 | .el .IP "\f(CWEV_WRITE\fR" 4 |
1251 | .el .IP "\f(CWEV_WRITE\fR" 4 |
1009 | .IX Item "EV_WRITE" |
1252 | .IX Item "EV_WRITE" |
1010 | .PD |
1253 | .PD |
1011 | The file descriptor in the \f(CW\*(C`ev_io\*(C'\fR watcher has become readable and/or |
1254 | The file descriptor in the \f(CW\*(C`ev_io\*(C'\fR watcher has become readable and/or |
1012 | writable. |
1255 | writable. |
1013 | .ie n .IP """EV_TIMEOUT""" 4 |
1256 | .ie n .IP """EV_TIMER""" 4 |
1014 | .el .IP "\f(CWEV_TIMEOUT\fR" 4 |
1257 | .el .IP "\f(CWEV_TIMER\fR" 4 |
1015 | .IX Item "EV_TIMEOUT" |
1258 | .IX Item "EV_TIMER" |
1016 | The \f(CW\*(C`ev_timer\*(C'\fR watcher has timed out. |
1259 | The \f(CW\*(C`ev_timer\*(C'\fR watcher has timed out. |
1017 | .ie n .IP """EV_PERIODIC""" 4 |
1260 | .ie n .IP """EV_PERIODIC""" 4 |
1018 | .el .IP "\f(CWEV_PERIODIC\fR" 4 |
1261 | .el .IP "\f(CWEV_PERIODIC\fR" 4 |
1019 | .IX Item "EV_PERIODIC" |
1262 | .IX Item "EV_PERIODIC" |
1020 | The \f(CW\*(C`ev_periodic\*(C'\fR watcher has timed out. |
1263 | The \f(CW\*(C`ev_periodic\*(C'\fR watcher has timed out. |
… | |
… | |
1040 | .PD 0 |
1283 | .PD 0 |
1041 | .ie n .IP """EV_CHECK""" 4 |
1284 | .ie n .IP """EV_CHECK""" 4 |
1042 | .el .IP "\f(CWEV_CHECK\fR" 4 |
1285 | .el .IP "\f(CWEV_CHECK\fR" 4 |
1043 | .IX Item "EV_CHECK" |
1286 | .IX Item "EV_CHECK" |
1044 | .PD |
1287 | .PD |
1045 | All \f(CW\*(C`ev_prepare\*(C'\fR watchers are invoked just \fIbefore\fR \f(CW\*(C`ev_loop\*(C'\fR starts |
1288 | All \f(CW\*(C`ev_prepare\*(C'\fR watchers are invoked just \fIbefore\fR \f(CW\*(C`ev_run\*(C'\fR starts |
1046 | to gather new events, and all \f(CW\*(C`ev_check\*(C'\fR watchers are invoked just after |
1289 | to gather new events, and all \f(CW\*(C`ev_check\*(C'\fR watchers are invoked just after |
1047 | \&\f(CW\*(C`ev_loop\*(C'\fR has gathered them, but before it invokes any callbacks for any |
1290 | \&\f(CW\*(C`ev_run\*(C'\fR has gathered them, but before it invokes any callbacks for any |
1048 | received events. Callbacks of both watcher types can start and stop as |
1291 | received events. Callbacks of both watcher types can start and stop as |
1049 | many watchers as they want, and all of them will be taken into account |
1292 | many watchers as they want, and all of them will be taken into account |
1050 | (for example, a \f(CW\*(C`ev_prepare\*(C'\fR watcher might start an idle watcher to keep |
1293 | (for example, a \f(CW\*(C`ev_prepare\*(C'\fR watcher might start an idle watcher to keep |
1051 | \&\f(CW\*(C`ev_loop\*(C'\fR from blocking). |
1294 | \&\f(CW\*(C`ev_run\*(C'\fR from blocking). |
1052 | .ie n .IP """EV_EMBED""" 4 |
1295 | .ie n .IP """EV_EMBED""" 4 |
1053 | .el .IP "\f(CWEV_EMBED\fR" 4 |
1296 | .el .IP "\f(CWEV_EMBED\fR" 4 |
1054 | .IX Item "EV_EMBED" |
1297 | .IX Item "EV_EMBED" |
1055 | The embedded event loop specified in the \f(CW\*(C`ev_embed\*(C'\fR watcher needs attention. |
1298 | The embedded event loop specified in the \f(CW\*(C`ev_embed\*(C'\fR watcher needs attention. |
1056 | .ie n .IP """EV_FORK""" 4 |
1299 | .ie n .IP """EV_FORK""" 4 |
1057 | .el .IP "\f(CWEV_FORK\fR" 4 |
1300 | .el .IP "\f(CWEV_FORK\fR" 4 |
1058 | .IX Item "EV_FORK" |
1301 | .IX Item "EV_FORK" |
1059 | The event loop has been resumed in the child process after fork (see |
1302 | The event loop has been resumed in the child process after fork (see |
1060 | \&\f(CW\*(C`ev_fork\*(C'\fR). |
1303 | \&\f(CW\*(C`ev_fork\*(C'\fR). |
|
|
1304 | .ie n .IP """EV_CLEANUP""" 4 |
|
|
1305 | .el .IP "\f(CWEV_CLEANUP\fR" 4 |
|
|
1306 | .IX Item "EV_CLEANUP" |
|
|
1307 | The event loop is about to be destroyed (see \f(CW\*(C`ev_cleanup\*(C'\fR). |
1061 | .ie n .IP """EV_ASYNC""" 4 |
1308 | .ie n .IP """EV_ASYNC""" 4 |
1062 | .el .IP "\f(CWEV_ASYNC\fR" 4 |
1309 | .el .IP "\f(CWEV_ASYNC\fR" 4 |
1063 | .IX Item "EV_ASYNC" |
1310 | .IX Item "EV_ASYNC" |
1064 | The given async watcher has been asynchronously notified (see \f(CW\*(C`ev_async\*(C'\fR). |
1311 | The given async watcher has been asynchronously notified (see \f(CW\*(C`ev_async\*(C'\fR). |
|
|
1312 | .ie n .IP """EV_CUSTOM""" 4 |
|
|
1313 | .el .IP "\f(CWEV_CUSTOM\fR" 4 |
|
|
1314 | .IX Item "EV_CUSTOM" |
|
|
1315 | Not ever sent (or otherwise used) by libev itself, but can be freely used |
|
|
1316 | by libev users to signal watchers (e.g. via \f(CW\*(C`ev_feed_event\*(C'\fR). |
1065 | .ie n .IP """EV_ERROR""" 4 |
1317 | .ie n .IP """EV_ERROR""" 4 |
1066 | .el .IP "\f(CWEV_ERROR\fR" 4 |
1318 | .el .IP "\f(CWEV_ERROR\fR" 4 |
1067 | .IX Item "EV_ERROR" |
1319 | .IX Item "EV_ERROR" |
1068 | An unspecified error has occurred, the watcher has been stopped. This might |
1320 | An unspecified error has occurred, the watcher has been stopped. This might |
1069 | happen because the watcher could not be properly started because libev |
1321 | happen because the watcher could not be properly started because libev |
… | |
… | |
1079 | example it might indicate that a fd is readable or writable, and if your |
1331 | example it might indicate that a fd is readable or writable, and if your |
1080 | callbacks is well-written it can just attempt the operation and cope with |
1332 | callbacks is well-written it can just attempt the operation and cope with |
1081 | the error from \fIread()\fR or \fIwrite()\fR. This will not work in multi-threaded |
1333 | the error from \fIread()\fR or \fIwrite()\fR. This will not work in multi-threaded |
1082 | programs, though, as the fd could already be closed and reused for another |
1334 | programs, though, as the fd could already be closed and reused for another |
1083 | thing, so beware. |
1335 | thing, so beware. |
1084 | .Sh "\s-1GENERIC\s0 \s-1WATCHER\s0 \s-1FUNCTIONS\s0" |
1336 | .SS "\s-1GENERIC\s0 \s-1WATCHER\s0 \s-1FUNCTIONS\s0" |
1085 | .IX Subsection "GENERIC WATCHER FUNCTIONS" |
1337 | .IX Subsection "GENERIC WATCHER FUNCTIONS" |
1086 | .ie n .IP """ev_init"" (ev_TYPE *watcher, callback)" 4 |
1338 | .ie n .IP """ev_init"" (ev_TYPE *watcher, callback)" 4 |
1087 | .el .IP "\f(CWev_init\fR (ev_TYPE *watcher, callback)" 4 |
1339 | .el .IP "\f(CWev_init\fR (ev_TYPE *watcher, callback)" 4 |
1088 | .IX Item "ev_init (ev_TYPE *watcher, callback)" |
1340 | .IX Item "ev_init (ev_TYPE *watcher, callback)" |
1089 | This macro initialises the generic portion of a watcher. The contents |
1341 | This macro initialises the generic portion of a watcher. The contents |
… | |
… | |
1104 | .Vb 3 |
1356 | .Vb 3 |
1105 | \& ev_io w; |
1357 | \& ev_io w; |
1106 | \& ev_init (&w, my_cb); |
1358 | \& ev_init (&w, my_cb); |
1107 | \& ev_io_set (&w, STDIN_FILENO, EV_READ); |
1359 | \& ev_io_set (&w, STDIN_FILENO, EV_READ); |
1108 | .Ve |
1360 | .Ve |
1109 | .ie n .IP """ev_TYPE_set"" (ev_TYPE *, [args])" 4 |
1361 | .ie n .IP """ev_TYPE_set"" (ev_TYPE *watcher, [args])" 4 |
1110 | .el .IP "\f(CWev_TYPE_set\fR (ev_TYPE *, [args])" 4 |
1362 | .el .IP "\f(CWev_TYPE_set\fR (ev_TYPE *watcher, [args])" 4 |
1111 | .IX Item "ev_TYPE_set (ev_TYPE *, [args])" |
1363 | .IX Item "ev_TYPE_set (ev_TYPE *watcher, [args])" |
1112 | This macro initialises the type-specific parts of a watcher. You need to |
1364 | This macro initialises the type-specific parts of a watcher. You need to |
1113 | call \f(CW\*(C`ev_init\*(C'\fR at least once before you call this macro, but you can |
1365 | call \f(CW\*(C`ev_init\*(C'\fR at least once before you call this macro, but you can |
1114 | call \f(CW\*(C`ev_TYPE_set\*(C'\fR any number of times. You must not, however, call this |
1366 | call \f(CW\*(C`ev_TYPE_set\*(C'\fR any number of times. You must not, however, call this |
1115 | macro on a watcher that is active (it can be pending, however, which is a |
1367 | macro on a watcher that is active (it can be pending, however, which is a |
1116 | difference to the \f(CW\*(C`ev_init\*(C'\fR macro). |
1368 | difference to the \f(CW\*(C`ev_init\*(C'\fR macro). |
… | |
… | |
1129 | Example: Initialise and set an \f(CW\*(C`ev_io\*(C'\fR watcher in one step. |
1381 | Example: Initialise and set an \f(CW\*(C`ev_io\*(C'\fR watcher in one step. |
1130 | .Sp |
1382 | .Sp |
1131 | .Vb 1 |
1383 | .Vb 1 |
1132 | \& ev_io_init (&w, my_cb, STDIN_FILENO, EV_READ); |
1384 | \& ev_io_init (&w, my_cb, STDIN_FILENO, EV_READ); |
1133 | .Ve |
1385 | .Ve |
1134 | .ie n .IP """ev_TYPE_start"" (loop *, ev_TYPE *watcher)" 4 |
1386 | .ie n .IP """ev_TYPE_start"" (loop, ev_TYPE *watcher)" 4 |
1135 | .el .IP "\f(CWev_TYPE_start\fR (loop *, ev_TYPE *watcher)" 4 |
1387 | .el .IP "\f(CWev_TYPE_start\fR (loop, ev_TYPE *watcher)" 4 |
1136 | .IX Item "ev_TYPE_start (loop *, ev_TYPE *watcher)" |
1388 | .IX Item "ev_TYPE_start (loop, ev_TYPE *watcher)" |
1137 | Starts (activates) the given watcher. Only active watchers will receive |
1389 | Starts (activates) the given watcher. Only active watchers will receive |
1138 | events. If the watcher is already active nothing will happen. |
1390 | events. If the watcher is already active nothing will happen. |
1139 | .Sp |
1391 | .Sp |
1140 | Example: Start the \f(CW\*(C`ev_io\*(C'\fR watcher that is being abused as example in this |
1392 | Example: Start the \f(CW\*(C`ev_io\*(C'\fR watcher that is being abused as example in this |
1141 | whole section. |
1393 | whole section. |
1142 | .Sp |
1394 | .Sp |
1143 | .Vb 1 |
1395 | .Vb 1 |
1144 | \& ev_io_start (EV_DEFAULT_UC, &w); |
1396 | \& ev_io_start (EV_DEFAULT_UC, &w); |
1145 | .Ve |
1397 | .Ve |
1146 | .ie n .IP """ev_TYPE_stop"" (loop *, ev_TYPE *watcher)" 4 |
1398 | .ie n .IP """ev_TYPE_stop"" (loop, ev_TYPE *watcher)" 4 |
1147 | .el .IP "\f(CWev_TYPE_stop\fR (loop *, ev_TYPE *watcher)" 4 |
1399 | .el .IP "\f(CWev_TYPE_stop\fR (loop, ev_TYPE *watcher)" 4 |
1148 | .IX Item "ev_TYPE_stop (loop *, ev_TYPE *watcher)" |
1400 | .IX Item "ev_TYPE_stop (loop, ev_TYPE *watcher)" |
1149 | Stops the given watcher if active, and clears the pending status (whether |
1401 | Stops the given watcher if active, and clears the pending status (whether |
1150 | the watcher was active or not). |
1402 | the watcher was active or not). |
1151 | .Sp |
1403 | .Sp |
1152 | It is possible that stopped watchers are pending \- for example, |
1404 | It is possible that stopped watchers are pending \- for example, |
1153 | non-repeating timers are being stopped when they become pending \- but |
1405 | non-repeating timers are being stopped when they become pending \- but |
… | |
… | |
1172 | Returns the callback currently set on the watcher. |
1424 | Returns the callback currently set on the watcher. |
1173 | .IP "ev_cb_set (ev_TYPE *watcher, callback)" 4 |
1425 | .IP "ev_cb_set (ev_TYPE *watcher, callback)" 4 |
1174 | .IX Item "ev_cb_set (ev_TYPE *watcher, callback)" |
1426 | .IX Item "ev_cb_set (ev_TYPE *watcher, callback)" |
1175 | Change the callback. You can change the callback at virtually any time |
1427 | Change the callback. You can change the callback at virtually any time |
1176 | (modulo threads). |
1428 | (modulo threads). |
1177 | .IP "ev_set_priority (ev_TYPE *watcher, priority)" 4 |
1429 | .IP "ev_set_priority (ev_TYPE *watcher, int priority)" 4 |
1178 | .IX Item "ev_set_priority (ev_TYPE *watcher, priority)" |
1430 | .IX Item "ev_set_priority (ev_TYPE *watcher, int priority)" |
1179 | .PD 0 |
1431 | .PD 0 |
1180 | .IP "int ev_priority (ev_TYPE *watcher)" 4 |
1432 | .IP "int ev_priority (ev_TYPE *watcher)" 4 |
1181 | .IX Item "int ev_priority (ev_TYPE *watcher)" |
1433 | .IX Item "int ev_priority (ev_TYPE *watcher)" |
1182 | .PD |
1434 | .PD |
1183 | Set and query the priority of the watcher. The priority is a small |
1435 | Set and query the priority of the watcher. The priority is a small |
1184 | integer between \f(CW\*(C`EV_MAXPRI\*(C'\fR (default: \f(CW2\fR) and \f(CW\*(C`EV_MINPRI\*(C'\fR |
1436 | integer between \f(CW\*(C`EV_MAXPRI\*(C'\fR (default: \f(CW2\fR) and \f(CW\*(C`EV_MINPRI\*(C'\fR |
1185 | (default: \f(CW\*(C`\-2\*(C'\fR). Pending watchers with higher priority will be invoked |
1437 | (default: \f(CW\*(C`\-2\*(C'\fR). Pending watchers with higher priority will be invoked |
1186 | before watchers with lower priority, but priority will not keep watchers |
1438 | before watchers with lower priority, but priority will not keep watchers |
1187 | from being executed (except for \f(CW\*(C`ev_idle\*(C'\fR watchers). |
1439 | from being executed (except for \f(CW\*(C`ev_idle\*(C'\fR watchers). |
1188 | .Sp |
1440 | .Sp |
1189 | This means that priorities are \fIonly\fR used for ordering callback |
|
|
1190 | invocation after new events have been received. This is useful, for |
|
|
1191 | example, to reduce latency after idling, or more often, to bind two |
|
|
1192 | watchers on the same event and make sure one is called first. |
|
|
1193 | .Sp |
|
|
1194 | If you need to suppress invocation when higher priority events are pending |
1441 | If you need to suppress invocation when higher priority events are pending |
1195 | you need to look at \f(CW\*(C`ev_idle\*(C'\fR watchers, which provide this functionality. |
1442 | you need to look at \f(CW\*(C`ev_idle\*(C'\fR watchers, which provide this functionality. |
1196 | .Sp |
1443 | .Sp |
1197 | You \fImust not\fR change the priority of a watcher as long as it is active or |
1444 | You \fImust not\fR change the priority of a watcher as long as it is active or |
1198 | pending. |
1445 | pending. |
1199 | .Sp |
|
|
1200 | The default priority used by watchers when no priority has been set is |
|
|
1201 | always \f(CW0\fR, which is supposed to not be too high and not be too low :). |
|
|
1202 | .Sp |
1446 | .Sp |
1203 | Setting a priority outside the range of \f(CW\*(C`EV_MINPRI\*(C'\fR to \f(CW\*(C`EV_MAXPRI\*(C'\fR is |
1447 | Setting a priority outside the range of \f(CW\*(C`EV_MINPRI\*(C'\fR to \f(CW\*(C`EV_MAXPRI\*(C'\fR is |
1204 | fine, as long as you do not mind that the priority value you query might |
1448 | fine, as long as you do not mind that the priority value you query might |
1205 | or might not have been clamped to the valid range. |
1449 | or might not have been clamped to the valid range. |
|
|
1450 | .Sp |
|
|
1451 | The default priority used by watchers when no priority has been set is |
|
|
1452 | always \f(CW0\fR, which is supposed to not be too high and not be too low :). |
|
|
1453 | .Sp |
|
|
1454 | See \*(L"\s-1WATCHER\s0 \s-1PRIORITY\s0 \s-1MODELS\s0\*(R", below, for a more thorough treatment of |
|
|
1455 | priorities. |
1206 | .IP "ev_invoke (loop, ev_TYPE *watcher, int revents)" 4 |
1456 | .IP "ev_invoke (loop, ev_TYPE *watcher, int revents)" 4 |
1207 | .IX Item "ev_invoke (loop, ev_TYPE *watcher, int revents)" |
1457 | .IX Item "ev_invoke (loop, ev_TYPE *watcher, int revents)" |
1208 | 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 |
1458 | 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 |
1209 | \&\f(CW\*(C`loop\*(C'\fR nor \f(CW\*(C`revents\*(C'\fR need to be valid as long as the watcher callback |
1459 | \&\f(CW\*(C`loop\*(C'\fR nor \f(CW\*(C`revents\*(C'\fR need to be valid as long as the watcher callback |
1210 | can deal with that fact, as both are simply passed through to the |
1460 | can deal with that fact, as both are simply passed through to the |
… | |
… | |
1215 | returns its \f(CW\*(C`revents\*(C'\fR bitset (as if its callback was invoked). If the |
1465 | returns its \f(CW\*(C`revents\*(C'\fR bitset (as if its callback was invoked). If the |
1216 | watcher isn't pending it does nothing and returns \f(CW0\fR. |
1466 | watcher isn't pending it does nothing and returns \f(CW0\fR. |
1217 | .Sp |
1467 | .Sp |
1218 | Sometimes it can be useful to \*(L"poll\*(R" a watcher instead of waiting for its |
1468 | Sometimes it can be useful to \*(L"poll\*(R" a watcher instead of waiting for its |
1219 | callback to be invoked, which can be accomplished with this function. |
1469 | callback to be invoked, which can be accomplished with this function. |
1220 | .Sh "\s-1ASSOCIATING\s0 \s-1CUSTOM\s0 \s-1DATA\s0 \s-1WITH\s0 A \s-1WATCHER\s0" |
1470 | .IP "ev_feed_event (loop, ev_TYPE *watcher, int revents)" 4 |
1221 | .IX Subsection "ASSOCIATING CUSTOM DATA WITH A WATCHER" |
1471 | .IX Item "ev_feed_event (loop, ev_TYPE *watcher, int revents)" |
1222 | Each watcher has, by default, a member \f(CW\*(C`void *data\*(C'\fR that you can change |
1472 | Feeds the given event set into the event loop, as if the specified event |
1223 | and read at any time: libev will completely ignore it. This can be used |
1473 | had happened for the specified watcher (which must be a pointer to an |
1224 | to associate arbitrary data with your watcher. If you need more data and |
1474 | initialised but not necessarily started event watcher). Obviously you must |
1225 | don't want to allocate memory and store a pointer to it in that data |
1475 | not free the watcher as long as it has pending events. |
1226 | member, you can also \*(L"subclass\*(R" the watcher type and provide your own |
1476 | .Sp |
1227 | data: |
1477 | Stopping the watcher, letting libev invoke it, or calling |
|
|
1478 | \&\f(CW\*(C`ev_clear_pending\*(C'\fR will clear the pending event, even if the watcher was |
|
|
1479 | not started in the first place. |
|
|
1480 | .Sp |
|
|
1481 | See also \f(CW\*(C`ev_feed_fd_event\*(C'\fR and \f(CW\*(C`ev_feed_signal_event\*(C'\fR for related |
|
|
1482 | functions that do not need a watcher. |
1228 | .PP |
1483 | .PP |
|
|
1484 | See also the \*(L"\s-1ASSOCIATING\s0 \s-1CUSTOM\s0 \s-1DATA\s0 \s-1WITH\s0 A \s-1WATCHER\s0\*(R" and \*(L"\s-1BUILDING\s0 \s-1YOUR\s0 |
|
|
1485 | \&\s-1OWN\s0 \s-1COMPOSITE\s0 \s-1WATCHERS\s0\*(R" idioms. |
|
|
1486 | .SS "\s-1WATCHER\s0 \s-1STATES\s0" |
|
|
1487 | .IX Subsection "WATCHER STATES" |
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1488 | There are various watcher states mentioned throughout this manual \- |
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1489 | active, pending and so on. In this section these states and the rules to |
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1490 | transition between them will be described in more detail \- and while these |
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1491 | rules might look complicated, they usually do \*(L"the right thing\*(R". |
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1492 | .IP "initialiased" 4 |
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1493 | .IX Item "initialiased" |
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1494 | Before a watcher can be registered with the event looop it has to be |
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1495 | initialised. This can be done with a call to \f(CW\*(C`ev_TYPE_init\*(C'\fR, or calls to |
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1496 | \&\f(CW\*(C`ev_init\*(C'\fR followed by the watcher-specific \f(CW\*(C`ev_TYPE_set\*(C'\fR function. |
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1497 | .Sp |
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1498 | In this state it is simply some block of memory that is suitable for |
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1499 | use in an event loop. It can be moved around, freed, reused etc. at |
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1500 | will \- as long as you either keep the memory contents intact, or call |
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1501 | \&\f(CW\*(C`ev_TYPE_init\*(C'\fR again. |
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1502 | .IP "started/running/active" 4 |
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1503 | .IX Item "started/running/active" |
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1504 | Once a watcher has been started with a call to \f(CW\*(C`ev_TYPE_start\*(C'\fR it becomes |
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1505 | property of the event loop, and is actively waiting for events. While in |
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1506 | this state it cannot be accessed (except in a few documented ways), moved, |
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1507 | freed or anything else \- the only legal thing is to keep a pointer to it, |
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1508 | and call libev functions on it that are documented to work on active watchers. |
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1509 | .IP "pending" 4 |
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1510 | .IX Item "pending" |
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1511 | If a watcher is active and libev determines that an event it is interested |
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1512 | in has occurred (such as a timer expiring), it will become pending. It will |
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1513 | stay in this pending state until either it is stopped or its callback is |
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1514 | about to be invoked, so it is not normally pending inside the watcher |
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1515 | callback. |
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1516 | .Sp |
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1517 | The watcher might or might not be active while it is pending (for example, |
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1518 | an expired non-repeating timer can be pending but no longer active). If it |
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1519 | is stopped, it can be freely accessed (e.g. by calling \f(CW\*(C`ev_TYPE_set\*(C'\fR), |
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1520 | but it is still property of the event loop at this time, so cannot be |
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1521 | moved, freed or reused. And if it is active the rules described in the |
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1522 | previous item still apply. |
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1523 | .Sp |
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1524 | It is also possible to feed an event on a watcher that is not active (e.g. |
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1525 | via \f(CW\*(C`ev_feed_event\*(C'\fR), in which case it becomes pending without being |
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1526 | active. |
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1527 | .IP "stopped" 4 |
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1528 | .IX Item "stopped" |
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1529 | A watcher can be stopped implicitly by libev (in which case it might still |
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1530 | be pending), or explicitly by calling its \f(CW\*(C`ev_TYPE_stop\*(C'\fR function. The |
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1531 | latter will clear any pending state the watcher might be in, regardless |
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1532 | of whether it was active or not, so stopping a watcher explicitly before |
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1533 | freeing it is often a good idea. |
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1534 | .Sp |
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1535 | While stopped (and not pending) the watcher is essentially in the |
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1536 | initialised state, that is, it can be reused, moved, modified in any way |
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1537 | you wish (but when you trash the memory block, you need to \f(CW\*(C`ev_TYPE_init\*(C'\fR |
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1538 | it again). |
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1539 | .SS "\s-1WATCHER\s0 \s-1PRIORITY\s0 \s-1MODELS\s0" |
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1540 | .IX Subsection "WATCHER PRIORITY MODELS" |
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1541 | Many event loops support \fIwatcher priorities\fR, which are usually small |
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1542 | integers that influence the ordering of event callback invocation |
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1543 | between watchers in some way, all else being equal. |
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1544 | .PP |
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1545 | In libev, Watcher priorities can be set using \f(CW\*(C`ev_set_priority\*(C'\fR. See its |
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1546 | description for the more technical details such as the actual priority |
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1547 | range. |
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1548 | .PP |
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1549 | There are two common ways how these these priorities are being interpreted |
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1550 | by event loops: |
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1551 | .PP |
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1552 | In the more common lock-out model, higher priorities \*(L"lock out\*(R" invocation |
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1553 | of lower priority watchers, which means as long as higher priority |
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1554 | watchers receive events, lower priority watchers are not being invoked. |
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1555 | .PP |
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1556 | The less common only-for-ordering model uses priorities solely to order |
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1557 | callback invocation within a single event loop iteration: Higher priority |
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1558 | watchers are invoked before lower priority ones, but they all get invoked |
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1559 | before polling for new events. |
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1560 | .PP |
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1561 | Libev uses the second (only-for-ordering) model for all its watchers |
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1562 | except for idle watchers (which use the lock-out model). |
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1563 | .PP |
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1564 | The rationale behind this is that implementing the lock-out model for |
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1565 | watchers is not well supported by most kernel interfaces, and most event |
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1566 | libraries will just poll for the same events again and again as long as |
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1567 | their callbacks have not been executed, which is very inefficient in the |
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1568 | common case of one high-priority watcher locking out a mass of lower |
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1569 | priority ones. |
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1570 | .PP |
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1571 | Static (ordering) priorities are most useful when you have two or more |
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1572 | watchers handling the same resource: a typical usage example is having an |
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1573 | \&\f(CW\*(C`ev_io\*(C'\fR watcher to receive data, and an associated \f(CW\*(C`ev_timer\*(C'\fR to handle |
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1574 | timeouts. Under load, data might be received while the program handles |
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1575 | other jobs, but since timers normally get invoked first, the timeout |
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1576 | handler will be executed before checking for data. In that case, giving |
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1577 | the timer a lower priority than the I/O watcher ensures that I/O will be |
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1578 | handled first even under adverse conditions (which is usually, but not |
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1579 | always, what you want). |
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1580 | .PP |
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1581 | Since idle watchers use the \*(L"lock-out\*(R" model, meaning that idle watchers |
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1582 | will only be executed when no same or higher priority watchers have |
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1583 | received events, they can be used to implement the \*(L"lock-out\*(R" model when |
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1584 | required. |
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1585 | .PP |
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1586 | For example, to emulate how many other event libraries handle priorities, |
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1587 | you can associate an \f(CW\*(C`ev_idle\*(C'\fR watcher to each such watcher, and in |
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1588 | the normal watcher callback, you just start the idle watcher. The real |
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1589 | processing is done in the idle watcher callback. This causes libev to |
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1590 | continuously poll and process kernel event data for the watcher, but when |
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1591 | the lock-out case is known to be rare (which in turn is rare :), this is |
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1592 | workable. |
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1593 | .PP |
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1594 | Usually, however, the lock-out model implemented that way will perform |
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1595 | miserably under the type of load it was designed to handle. In that case, |
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1596 | it might be preferable to stop the real watcher before starting the |
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1597 | idle watcher, so the kernel will not have to process the event in case |
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1598 | the actual processing will be delayed for considerable time. |
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1599 | .PP |
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1600 | Here is an example of an I/O watcher that should run at a strictly lower |
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1601 | priority than the default, and which should only process data when no |
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1602 | other events are pending: |
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1603 | .PP |
1229 | .Vb 7 |
1604 | .Vb 2 |
1230 | \& struct my_io |
1605 | \& ev_idle idle; // actual processing watcher |
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1606 | \& ev_io io; // actual event watcher |
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1607 | \& |
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1608 | \& static void |
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1609 | \& io_cb (EV_P_ ev_io *w, int revents) |
1231 | \& { |
1610 | \& { |
1232 | \& ev_io io; |
1611 | \& // stop the I/O watcher, we received the event, but |
1233 | \& int otherfd; |
1612 | \& // are not yet ready to handle it. |
1234 | \& void *somedata; |
1613 | \& ev_io_stop (EV_A_ w); |
1235 | \& struct whatever *mostinteresting; |
1614 | \& |
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1615 | \& // start the idle watcher to handle the actual event. |
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1616 | \& // it will not be executed as long as other watchers |
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1617 | \& // with the default priority are receiving events. |
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1618 | \& ev_idle_start (EV_A_ &idle); |
1236 | \& }; |
1619 | \& } |
1237 | \& |
1620 | \& |
1238 | \& ... |
1621 | \& static void |
1239 | \& struct my_io w; |
1622 | \& idle_cb (EV_P_ ev_idle *w, int revents) |
1240 | \& ev_io_init (&w.io, my_cb, fd, EV_READ); |
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1241 | .Ve |
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1242 | .PP |
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1243 | And since your callback will be called with a pointer to the watcher, you |
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1244 | can cast it back to your own type: |
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1245 | .PP |
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1246 | .Vb 5 |
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1247 | \& static void my_cb (struct ev_loop *loop, ev_io *w_, int revents) |
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1248 | \& { |
1623 | \& { |
1249 | \& struct my_io *w = (struct my_io *)w_; |
1624 | \& // actual processing |
1250 | \& ... |
1625 | \& read (STDIN_FILENO, ...); |
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1626 | \& |
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1627 | \& // have to start the I/O watcher again, as |
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1628 | \& // we have handled the event |
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1629 | \& ev_io_start (EV_P_ &io); |
1251 | \& } |
1630 | \& } |
1252 | .Ve |
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1253 | .PP |
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1254 | More interesting and less C\-conformant ways of casting your callback type |
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1255 | instead have been omitted. |
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1256 | .PP |
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1257 | Another common scenario is to use some data structure with multiple |
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1258 | embedded watchers: |
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1259 | .PP |
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1260 | .Vb 6 |
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1261 | \& struct my_biggy |
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1262 | \& { |
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1263 | \& int some_data; |
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1264 | \& ev_timer t1; |
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1265 | \& ev_timer t2; |
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1266 | \& } |
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1267 | .Ve |
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1268 | .PP |
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1269 | In this case getting the pointer to \f(CW\*(C`my_biggy\*(C'\fR is a bit more |
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1270 | complicated: Either you store the address of your \f(CW\*(C`my_biggy\*(C'\fR struct |
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1271 | in the \f(CW\*(C`data\*(C'\fR member of the watcher (for woozies), or you need to use |
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1272 | some pointer arithmetic using \f(CW\*(C`offsetof\*(C'\fR inside your watchers (for real |
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1273 | programmers): |
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1274 | .PP |
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1275 | .Vb 1 |
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1276 | \& #include <stddef.h> |
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1277 | \& |
1631 | \& |
1278 | \& static void |
1632 | \& // initialisation |
1279 | \& t1_cb (EV_P_ ev_timer *w, int revents) |
1633 | \& ev_idle_init (&idle, idle_cb); |
1280 | \& { |
1634 | \& ev_io_init (&io, io_cb, STDIN_FILENO, EV_READ); |
1281 | \& struct my_biggy big = (struct my_biggy * |
1635 | \& ev_io_start (EV_DEFAULT_ &io); |
1282 | \& (((char *)w) \- offsetof (struct my_biggy, t1)); |
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1283 | \& } |
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1284 | \& |
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1285 | \& static void |
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1286 | \& t2_cb (EV_P_ ev_timer *w, int revents) |
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1287 | \& { |
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1288 | \& struct my_biggy big = (struct my_biggy * |
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1289 | \& (((char *)w) \- offsetof (struct my_biggy, t2)); |
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1290 | \& } |
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1291 | .Ve |
1636 | .Ve |
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1637 | .PP |
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1638 | In the \*(L"real\*(R" world, it might also be beneficial to start a timer, so that |
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1639 | low-priority connections can not be locked out forever under load. This |
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1640 | enables your program to keep a lower latency for important connections |
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1641 | during short periods of high load, while not completely locking out less |
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1642 | important ones. |
1292 | .SH "WATCHER TYPES" |
1643 | .SH "WATCHER TYPES" |
1293 | .IX Header "WATCHER TYPES" |
1644 | .IX Header "WATCHER TYPES" |
1294 | This section describes each watcher in detail, but will not repeat |
1645 | This section describes each watcher in detail, but will not repeat |
1295 | information given in the last section. Any initialisation/set macros, |
1646 | information given in the last section. Any initialisation/set macros, |
1296 | functions and members specific to the watcher type are explained. |
1647 | functions and members specific to the watcher type are explained. |
… | |
… | |
1301 | watcher is stopped to your hearts content), or \fI[read\-write]\fR, which |
1652 | watcher is stopped to your hearts content), or \fI[read\-write]\fR, which |
1302 | means you can expect it to have some sensible content while the watcher |
1653 | means you can expect it to have some sensible content while the watcher |
1303 | is active, but you can also modify it. Modifying it may not do something |
1654 | is active, but you can also modify it. Modifying it may not do something |
1304 | sensible or take immediate effect (or do anything at all), but libev will |
1655 | sensible or take immediate effect (or do anything at all), but libev will |
1305 | not crash or malfunction in any way. |
1656 | not crash or malfunction in any way. |
1306 | .ie n .Sh """ev_io"" \- is this file descriptor readable or writable?" |
1657 | .ie n .SS """ev_io"" \- is this file descriptor readable or writable?" |
1307 | .el .Sh "\f(CWev_io\fP \- is this file descriptor readable or writable?" |
1658 | .el .SS "\f(CWev_io\fP \- is this file descriptor readable or writable?" |
1308 | .IX Subsection "ev_io - is this file descriptor readable or writable?" |
1659 | .IX Subsection "ev_io - is this file descriptor readable or writable?" |
1309 | I/O watchers check whether a file descriptor is readable or writable |
1660 | I/O watchers check whether a file descriptor is readable or writable |
1310 | in each iteration of the event loop, or, more precisely, when reading |
1661 | in each iteration of the event loop, or, more precisely, when reading |
1311 | would not block the process and writing would at least be able to write |
1662 | would not block the process and writing would at least be able to write |
1312 | some data. This behaviour is called level-triggering because you keep |
1663 | some data. This behaviour is called level-triggering because you keep |
… | |
… | |
1317 | In general you can register as many read and/or write event watchers per |
1668 | In general you can register as many read and/or write event watchers per |
1318 | fd as you want (as long as you don't confuse yourself). Setting all file |
1669 | fd as you want (as long as you don't confuse yourself). Setting all file |
1319 | descriptors to non-blocking mode is also usually a good idea (but not |
1670 | descriptors to non-blocking mode is also usually a good idea (but not |
1320 | required if you know what you are doing). |
1671 | required if you know what you are doing). |
1321 | .PP |
1672 | .PP |
1322 | If you cannot use non-blocking mode, then force the use of a |
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1323 | known-to-be-good backend (at the time of this writing, this includes only |
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1324 | \&\f(CW\*(C`EVBACKEND_SELECT\*(C'\fR and \f(CW\*(C`EVBACKEND_POLL\*(C'\fR). |
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1325 | .PP |
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1326 | Another thing you have to watch out for is that it is quite easy to |
1673 | Another thing you have to watch out for is that it is quite easy to |
1327 | receive \*(L"spurious\*(R" readiness notifications, that is your callback might |
1674 | receive \*(L"spurious\*(R" readiness notifications, that is, your callback might |
1328 | be called with \f(CW\*(C`EV_READ\*(C'\fR but a subsequent \f(CW\*(C`read\*(C'\fR(2) will actually block |
1675 | be called with \f(CW\*(C`EV_READ\*(C'\fR but a subsequent \f(CW\*(C`read\*(C'\fR(2) will actually block |
1329 | because there is no data. Not only are some backends known to create a |
1676 | because there is no data. It is very easy to get into this situation even |
1330 | lot of those (for example Solaris ports), it is very easy to get into |
1677 | with a relatively standard program structure. Thus it is best to always |
1331 | this situation even with a relatively standard program structure. Thus |
1678 | use non-blocking I/O: An extra \f(CW\*(C`read\*(C'\fR(2) returning \f(CW\*(C`EAGAIN\*(C'\fR is far |
1332 | it is best to always use non-blocking I/O: An extra \f(CW\*(C`read\*(C'\fR(2) returning |
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1333 | \&\f(CW\*(C`EAGAIN\*(C'\fR is far preferable to a program hanging until some data arrives. |
1679 | preferable to a program hanging until some data arrives. |
1334 | .PP |
1680 | .PP |
1335 | If you cannot run the fd in non-blocking mode (for example you should |
1681 | If you cannot run the fd in non-blocking mode (for example you should |
1336 | not play around with an Xlib connection), then you have to separately |
1682 | not play around with an Xlib connection), then you have to separately |
1337 | re-test whether a file descriptor is really ready with a known-to-be good |
1683 | re-test whether a file descriptor is really ready with a known-to-be good |
1338 | interface such as poll (fortunately in our Xlib example, Xlib already |
1684 | interface such as poll (fortunately in the case of Xlib, it already does |
1339 | does this on its own, so its quite safe to use). Some people additionally |
1685 | this on its own, so its quite safe to use). Some people additionally |
1340 | use \f(CW\*(C`SIGALRM\*(C'\fR and an interval timer, just to be sure you won't block |
1686 | use \f(CW\*(C`SIGALRM\*(C'\fR and an interval timer, just to be sure you won't block |
1341 | indefinitely. |
1687 | indefinitely. |
1342 | .PP |
1688 | .PP |
1343 | But really, best use non-blocking mode. |
1689 | But really, best use non-blocking mode. |
1344 | .PP |
1690 | .PP |
… | |
… | |
1374 | .PP |
1720 | .PP |
1375 | There is no workaround possible except not registering events |
1721 | There is no workaround possible except not registering events |
1376 | for potentially \f(CW\*(C`dup ()\*(C'\fR'ed file descriptors, or to resort to |
1722 | for potentially \f(CW\*(C`dup ()\*(C'\fR'ed file descriptors, or to resort to |
1377 | \&\f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or \f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
1723 | \&\f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or \f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
1378 | .PP |
1724 | .PP |
|
|
1725 | \fIThe special problem of files\fR |
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|
1726 | .IX Subsection "The special problem of files" |
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1727 | .PP |
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|
1728 | Many people try to use \f(CW\*(C`select\*(C'\fR (or libev) on file descriptors |
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1729 | representing files, and expect it to become ready when their program |
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1730 | doesn't block on disk accesses (which can take a long time on their own). |
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1731 | .PP |
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1732 | However, this cannot ever work in the \*(L"expected\*(R" way \- you get a readiness |
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1733 | notification as soon as the kernel knows whether and how much data is |
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1734 | there, and in the case of open files, that's always the case, so you |
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1735 | always get a readiness notification instantly, and your read (or possibly |
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1736 | write) will still block on the disk I/O. |
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1737 | .PP |
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1738 | Another way to view it is that in the case of sockets, pipes, character |
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1739 | devices and so on, there is another party (the sender) that delivers data |
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1740 | on its own, but in the case of files, there is no such thing: the disk |
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1741 | will not send data on its own, simply because it doesn't know what you |
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1742 | wish to read \- you would first have to request some data. |
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1743 | .PP |
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1744 | Since files are typically not-so-well supported by advanced notification |
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1745 | mechanism, libev tries hard to emulate \s-1POSIX\s0 behaviour with respect |
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1746 | to files, even though you should not use it. The reason for this is |
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1747 | convenience: sometimes you want to watch \s-1STDIN\s0 or \s-1STDOUT\s0, which is |
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1748 | usually a tty, often a pipe, but also sometimes files or special devices |
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1749 | (for example, \f(CW\*(C`epoll\*(C'\fR on Linux works with \fI/dev/random\fR but not with |
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1750 | \&\fI/dev/urandom\fR), and even though the file might better be served with |
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1751 | asynchronous I/O instead of with non-blocking I/O, it is still useful when |
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1752 | it \*(L"just works\*(R" instead of freezing. |
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1753 | .PP |
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1754 | So avoid file descriptors pointing to files when you know it (e.g. use |
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1755 | libeio), but use them when it is convenient, e.g. for \s-1STDIN/STDOUT\s0, or |
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1756 | when you rarely read from a file instead of from a socket, and want to |
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1757 | reuse the same code path. |
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1758 | .PP |
1379 | \fIThe special problem of fork\fR |
1759 | \fIThe special problem of fork\fR |
1380 | .IX Subsection "The special problem of fork" |
1760 | .IX Subsection "The special problem of fork" |
1381 | .PP |
1761 | .PP |
1382 | Some backends (epoll, kqueue) do not support \f(CW\*(C`fork ()\*(C'\fR at all or exhibit |
1762 | Some backends (epoll, kqueue) do not support \f(CW\*(C`fork ()\*(C'\fR at all or exhibit |
1383 | useless behaviour. Libev fully supports fork, but needs to be told about |
1763 | useless behaviour. Libev fully supports fork, but needs to be told about |
1384 | it in the child. |
1764 | it in the child if you want to continue to use it in the child. |
1385 | .PP |
1765 | .PP |
1386 | To support fork in your programs, you either have to call |
1766 | To support fork in your child processes, you have to call \f(CW\*(C`ev_loop_fork |
1387 | \&\f(CW\*(C`ev_default_fork ()\*(C'\fR or \f(CW\*(C`ev_loop_fork ()\*(C'\fR after a fork in the child, |
1767 | ()\*(C'\fR after a fork in the child, enable \f(CW\*(C`EVFLAG_FORKCHECK\*(C'\fR, or resort to |
1388 | enable \f(CW\*(C`EVFLAG_FORKCHECK\*(C'\fR, or resort to \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or |
1768 | \&\f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or \f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
1389 | \&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
|
|
1390 | .PP |
1769 | .PP |
1391 | \fIThe special problem of \s-1SIGPIPE\s0\fR |
1770 | \fIThe special problem of \s-1SIGPIPE\s0\fR |
1392 | .IX Subsection "The special problem of SIGPIPE" |
1771 | .IX Subsection "The special problem of SIGPIPE" |
1393 | .PP |
1772 | .PP |
1394 | While not really specific to libev, it is easy to forget about \f(CW\*(C`SIGPIPE\*(C'\fR: |
1773 | While not really specific to libev, it is easy to forget about \f(CW\*(C`SIGPIPE\*(C'\fR: |
… | |
… | |
1397 | this is sensible behaviour, for daemons, this is usually undesirable. |
1776 | this is sensible behaviour, for daemons, this is usually undesirable. |
1398 | .PP |
1777 | .PP |
1399 | So when you encounter spurious, unexplained daemon exits, make sure you |
1778 | So when you encounter spurious, unexplained daemon exits, make sure you |
1400 | ignore \s-1SIGPIPE\s0 (and maybe make sure you log the exit status of your daemon |
1779 | ignore \s-1SIGPIPE\s0 (and maybe make sure you log the exit status of your daemon |
1401 | somewhere, as that would have given you a big clue). |
1780 | somewhere, as that would have given you a big clue). |
|
|
1781 | .PP |
|
|
1782 | \fIThe special problem of \fIaccept()\fIing when you can't\fR |
|
|
1783 | .IX Subsection "The special problem of accept()ing when you can't" |
|
|
1784 | .PP |
|
|
1785 | Many implementations of the \s-1POSIX\s0 \f(CW\*(C`accept\*(C'\fR function (for example, |
|
|
1786 | found in post\-2004 Linux) have the peculiar behaviour of not removing a |
|
|
1787 | connection from the pending queue in all error cases. |
|
|
1788 | .PP |
|
|
1789 | For example, larger servers often run out of file descriptors (because |
|
|
1790 | of resource limits), causing \f(CW\*(C`accept\*(C'\fR to fail with \f(CW\*(C`ENFILE\*(C'\fR but not |
|
|
1791 | rejecting the connection, leading to libev signalling readiness on |
|
|
1792 | the next iteration again (the connection still exists after all), and |
|
|
1793 | typically causing the program to loop at 100% \s-1CPU\s0 usage. |
|
|
1794 | .PP |
|
|
1795 | Unfortunately, the set of errors that cause this issue differs between |
|
|
1796 | operating systems, there is usually little the app can do to remedy the |
|
|
1797 | situation, and no known thread-safe method of removing the connection to |
|
|
1798 | cope with overload is known (to me). |
|
|
1799 | .PP |
|
|
1800 | One of the easiest ways to handle this situation is to just ignore it |
|
|
1801 | \&\- when the program encounters an overload, it will just loop until the |
|
|
1802 | situation is over. While this is a form of busy waiting, no \s-1OS\s0 offers an |
|
|
1803 | event-based way to handle this situation, so it's the best one can do. |
|
|
1804 | .PP |
|
|
1805 | A better way to handle the situation is to log any errors other than |
|
|
1806 | \&\f(CW\*(C`EAGAIN\*(C'\fR and \f(CW\*(C`EWOULDBLOCK\*(C'\fR, making sure not to flood the log with such |
|
|
1807 | messages, and continue as usual, which at least gives the user an idea of |
|
|
1808 | what could be wrong (\*(L"raise the ulimit!\*(R"). For extra points one could stop |
|
|
1809 | the \f(CW\*(C`ev_io\*(C'\fR watcher on the listening fd \*(L"for a while\*(R", which reduces \s-1CPU\s0 |
|
|
1810 | usage. |
|
|
1811 | .PP |
|
|
1812 | If your program is single-threaded, then you could also keep a dummy file |
|
|
1813 | descriptor for overload situations (e.g. by opening \fI/dev/null\fR), and |
|
|
1814 | 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, |
|
|
1815 | close that fd, and create a new dummy fd. This will gracefully refuse |
|
|
1816 | clients under typical overload conditions. |
|
|
1817 | .PP |
|
|
1818 | The last way to handle it is to simply log the error and \f(CW\*(C`exit\*(C'\fR, as |
|
|
1819 | is often done with \f(CW\*(C`malloc\*(C'\fR failures, but this results in an easy |
|
|
1820 | opportunity for a DoS attack. |
1402 | .PP |
1821 | .PP |
1403 | \fIWatcher-Specific Functions\fR |
1822 | \fIWatcher-Specific Functions\fR |
1404 | .IX Subsection "Watcher-Specific Functions" |
1823 | .IX Subsection "Watcher-Specific Functions" |
1405 | .IP "ev_io_init (ev_io *, callback, int fd, int events)" 4 |
1824 | .IP "ev_io_init (ev_io *, callback, int fd, int events)" 4 |
1406 | .IX Item "ev_io_init (ev_io *, callback, int fd, int events)" |
1825 | .IX Item "ev_io_init (ev_io *, callback, int fd, int events)" |
… | |
… | |
1436 | \& ... |
1855 | \& ... |
1437 | \& struct ev_loop *loop = ev_default_init (0); |
1856 | \& struct ev_loop *loop = ev_default_init (0); |
1438 | \& ev_io stdin_readable; |
1857 | \& ev_io stdin_readable; |
1439 | \& ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ); |
1858 | \& ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ); |
1440 | \& ev_io_start (loop, &stdin_readable); |
1859 | \& ev_io_start (loop, &stdin_readable); |
1441 | \& ev_loop (loop, 0); |
1860 | \& ev_run (loop, 0); |
1442 | .Ve |
1861 | .Ve |
1443 | .ie n .Sh """ev_timer"" \- relative and optionally repeating timeouts" |
1862 | .ie n .SS """ev_timer"" \- relative and optionally repeating timeouts" |
1444 | .el .Sh "\f(CWev_timer\fP \- relative and optionally repeating timeouts" |
1863 | .el .SS "\f(CWev_timer\fP \- relative and optionally repeating timeouts" |
1445 | .IX Subsection "ev_timer - relative and optionally repeating timeouts" |
1864 | .IX Subsection "ev_timer - relative and optionally repeating timeouts" |
1446 | Timer watchers are simple relative timers that generate an event after a |
1865 | Timer watchers are simple relative timers that generate an event after a |
1447 | given time, and optionally repeating in regular intervals after that. |
1866 | given time, and optionally repeating in regular intervals after that. |
1448 | .PP |
1867 | .PP |
1449 | The timers are based on real time, that is, if you register an event that |
1868 | The timers are based on real time, that is, if you register an event that |
… | |
… | |
1451 | year, it will still time out after (roughly) one hour. \*(L"Roughly\*(R" because |
1870 | year, it will still time out after (roughly) one hour. \*(L"Roughly\*(R" because |
1452 | detecting time jumps is hard, and some inaccuracies are unavoidable (the |
1871 | detecting time jumps is hard, and some inaccuracies are unavoidable (the |
1453 | monotonic clock option helps a lot here). |
1872 | monotonic clock option helps a lot here). |
1454 | .PP |
1873 | .PP |
1455 | The callback is guaranteed to be invoked only \fIafter\fR its timeout has |
1874 | The callback is guaranteed to be invoked only \fIafter\fR its timeout has |
1456 | passed, but if multiple timers become ready during the same loop iteration |
1875 | passed (not \fIat\fR, so on systems with very low-resolution clocks this |
1457 | then order of execution is undefined. |
1876 | might introduce a small delay). If multiple timers become ready during the |
|
|
1877 | same loop iteration then the ones with earlier time-out values are invoked |
|
|
1878 | before ones of the same priority with later time-out values (but this is |
|
|
1879 | no longer true when a callback calls \f(CW\*(C`ev_run\*(C'\fR recursively). |
1458 | .PP |
1880 | .PP |
1459 | \fIBe smart about timeouts\fR |
1881 | \fIBe smart about timeouts\fR |
1460 | .IX Subsection "Be smart about timeouts" |
1882 | .IX Subsection "Be smart about timeouts" |
1461 | .PP |
1883 | .PP |
1462 | Many real-world problems involve some kind of timeout, usually for error |
1884 | Many real-world problems involve some kind of timeout, usually for error |
… | |
… | |
1509 | member and \f(CW\*(C`ev_timer_again\*(C'\fR. |
1931 | member and \f(CW\*(C`ev_timer_again\*(C'\fR. |
1510 | .Sp |
1932 | .Sp |
1511 | At start: |
1933 | At start: |
1512 | .Sp |
1934 | .Sp |
1513 | .Vb 3 |
1935 | .Vb 3 |
1514 | \& ev_timer_init (timer, callback); |
1936 | \& ev_init (timer, callback); |
1515 | \& timer\->repeat = 60.; |
1937 | \& timer\->repeat = 60.; |
1516 | \& ev_timer_again (loop, timer); |
1938 | \& ev_timer_again (loop, timer); |
1517 | .Ve |
1939 | .Ve |
1518 | .Sp |
1940 | .Sp |
1519 | Each time there is some activity: |
1941 | Each time there is some activity: |
… | |
… | |
1556 | \& ev_tstamp timeout = last_activity + 60.; |
1978 | \& ev_tstamp timeout = last_activity + 60.; |
1557 | \& |
1979 | \& |
1558 | \& // if last_activity + 60. is older than now, we did time out |
1980 | \& // if last_activity + 60. is older than now, we did time out |
1559 | \& if (timeout < now) |
1981 | \& if (timeout < now) |
1560 | \& { |
1982 | \& { |
1561 | \& // timeout occured, take action |
1983 | \& // timeout occurred, take action |
1562 | \& } |
1984 | \& } |
1563 | \& else |
1985 | \& else |
1564 | \& { |
1986 | \& { |
1565 | \& // callback was invoked, but there was some activity, re\-arm |
1987 | \& // callback was invoked, but there was some activity, re\-arm |
1566 | \& // the watcher to fire in last_activity + 60, which is |
1988 | \& // the watcher to fire in last_activity + 60, which is |
… | |
… | |
1588 | To start the timer, simply initialise the watcher and set \f(CW\*(C`last_activity\*(C'\fR |
2010 | To start the timer, simply initialise the watcher and set \f(CW\*(C`last_activity\*(C'\fR |
1589 | to the current time (meaning we just have some activity :), then call the |
2011 | to the current time (meaning we just have some activity :), then call the |
1590 | callback, which will \*(L"do the right thing\*(R" and start the timer: |
2012 | callback, which will \*(L"do the right thing\*(R" and start the timer: |
1591 | .Sp |
2013 | .Sp |
1592 | .Vb 3 |
2014 | .Vb 3 |
1593 | \& ev_timer_init (timer, callback); |
2015 | \& ev_init (timer, callback); |
1594 | \& last_activity = ev_now (loop); |
2016 | \& last_activity = ev_now (loop); |
1595 | \& callback (loop, timer, EV_TIMEOUT); |
2017 | \& callback (loop, timer, EV_TIMER); |
1596 | .Ve |
2018 | .Ve |
1597 | .Sp |
2019 | .Sp |
1598 | And when there is some activity, simply store the current time in |
2020 | And when there is some activity, simply store the current time in |
1599 | \&\f(CW\*(C`last_activity\*(C'\fR, no libev calls at all: |
2021 | \&\f(CW\*(C`last_activity\*(C'\fR, no libev calls at all: |
1600 | .Sp |
2022 | .Sp |
1601 | .Vb 1 |
2023 | .Vb 1 |
1602 | \& last_actiivty = ev_now (loop); |
2024 | \& last_activity = ev_now (loop); |
1603 | .Ve |
2025 | .Ve |
1604 | .Sp |
2026 | .Sp |
1605 | This technique is slightly more complex, but in most cases where the |
2027 | This technique is slightly more complex, but in most cases where the |
1606 | time-out is unlikely to be triggered, much more efficient. |
2028 | time-out is unlikely to be triggered, much more efficient. |
1607 | .Sp |
2029 | .Sp |
… | |
… | |
1644 | \fIThe special problem of time updates\fR |
2066 | \fIThe special problem of time updates\fR |
1645 | .IX Subsection "The special problem of time updates" |
2067 | .IX Subsection "The special problem of time updates" |
1646 | .PP |
2068 | .PP |
1647 | Establishing the current time is a costly operation (it usually takes at |
2069 | Establishing the current time is a costly operation (it usually takes at |
1648 | least two system calls): \s-1EV\s0 therefore updates its idea of the current |
2070 | least two system calls): \s-1EV\s0 therefore updates its idea of the current |
1649 | time only before and after \f(CW\*(C`ev_loop\*(C'\fR collects new events, which causes a |
2071 | time only before and after \f(CW\*(C`ev_run\*(C'\fR collects new events, which causes a |
1650 | growing difference between \f(CW\*(C`ev_now ()\*(C'\fR and \f(CW\*(C`ev_time ()\*(C'\fR when handling |
2072 | growing difference between \f(CW\*(C`ev_now ()\*(C'\fR and \f(CW\*(C`ev_time ()\*(C'\fR when handling |
1651 | lots of events in one iteration. |
2073 | lots of events in one iteration. |
1652 | .PP |
2074 | .PP |
1653 | The relative timeouts are calculated relative to the \f(CW\*(C`ev_now ()\*(C'\fR |
2075 | The relative timeouts are calculated relative to the \f(CW\*(C`ev_now ()\*(C'\fR |
1654 | time. This is usually the right thing as this timestamp refers to the time |
2076 | time. This is usually the right thing as this timestamp refers to the time |
… | |
… | |
1661 | .Ve |
2083 | .Ve |
1662 | .PP |
2084 | .PP |
1663 | If the event loop is suspended for a long time, you can also force an |
2085 | If the event loop is suspended for a long time, you can also force an |
1664 | update of the time returned by \f(CW\*(C`ev_now ()\*(C'\fR by calling \f(CW\*(C`ev_now_update |
2086 | update of the time returned by \f(CW\*(C`ev_now ()\*(C'\fR by calling \f(CW\*(C`ev_now_update |
1665 | ()\*(C'\fR. |
2087 | ()\*(C'\fR. |
|
|
2088 | .PP |
|
|
2089 | \fIThe special problems of suspended animation\fR |
|
|
2090 | .IX Subsection "The special problems of suspended animation" |
|
|
2091 | .PP |
|
|
2092 | When you leave the server world it is quite customary to hit machines that |
|
|
2093 | can suspend/hibernate \- what happens to the clocks during such a suspend? |
|
|
2094 | .PP |
|
|
2095 | Some quick tests made with a Linux 2.6.28 indicate that a suspend freezes |
|
|
2096 | all processes, while the clocks (\f(CW\*(C`times\*(C'\fR, \f(CW\*(C`CLOCK_MONOTONIC\*(C'\fR) continue |
|
|
2097 | to run until the system is suspended, but they will not advance while the |
|
|
2098 | system is suspended. That means, on resume, it will be as if the program |
|
|
2099 | was frozen for a few seconds, but the suspend time will not be counted |
|
|
2100 | towards \f(CW\*(C`ev_timer\*(C'\fR when a monotonic clock source is used. The real time |
|
|
2101 | clock advanced as expected, but if it is used as sole clocksource, then a |
|
|
2102 | long suspend would be detected as a time jump by libev, and timers would |
|
|
2103 | be adjusted accordingly. |
|
|
2104 | .PP |
|
|
2105 | I would not be surprised to see different behaviour in different between |
|
|
2106 | operating systems, \s-1OS\s0 versions or even different hardware. |
|
|
2107 | .PP |
|
|
2108 | The other form of suspend (job control, or sending a \s-1SIGSTOP\s0) will see a |
|
|
2109 | time jump in the monotonic clocks and the realtime clock. If the program |
|
|
2110 | is suspended for a very long time, and monotonic clock sources are in use, |
|
|
2111 | then you can expect \f(CW\*(C`ev_timer\*(C'\fRs to expire as the full suspension time |
|
|
2112 | will be counted towards the timers. When no monotonic clock source is in |
|
|
2113 | use, then libev will again assume a timejump and adjust accordingly. |
|
|
2114 | .PP |
|
|
2115 | It might be beneficial for this latter case to call \f(CW\*(C`ev_suspend\*(C'\fR |
|
|
2116 | and \f(CW\*(C`ev_resume\*(C'\fR in code that handles \f(CW\*(C`SIGTSTP\*(C'\fR, to at least get |
|
|
2117 | deterministic behaviour in this case (you can do nothing against |
|
|
2118 | \&\f(CW\*(C`SIGSTOP\*(C'\fR). |
1666 | .PP |
2119 | .PP |
1667 | \fIWatcher-Specific Functions and Data Members\fR |
2120 | \fIWatcher-Specific Functions and Data Members\fR |
1668 | .IX Subsection "Watcher-Specific Functions and Data Members" |
2121 | .IX Subsection "Watcher-Specific Functions and Data Members" |
1669 | .IP "ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)" 4 |
2122 | .IP "ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)" 4 |
1670 | .IX Item "ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)" |
2123 | .IX Item "ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)" |
… | |
… | |
1695 | If the timer is repeating, either start it if necessary (with the |
2148 | If the timer is repeating, either start it if necessary (with the |
1696 | \&\f(CW\*(C`repeat\*(C'\fR value), or reset the running timer to the \f(CW\*(C`repeat\*(C'\fR value. |
2149 | \&\f(CW\*(C`repeat\*(C'\fR value), or reset the running timer to the \f(CW\*(C`repeat\*(C'\fR value. |
1697 | .Sp |
2150 | .Sp |
1698 | This sounds a bit complicated, see \*(L"Be smart about timeouts\*(R", above, for a |
2151 | This sounds a bit complicated, see \*(L"Be smart about timeouts\*(R", above, for a |
1699 | usage example. |
2152 | usage example. |
|
|
2153 | .IP "ev_tstamp ev_timer_remaining (loop, ev_timer *)" 4 |
|
|
2154 | .IX Item "ev_tstamp ev_timer_remaining (loop, ev_timer *)" |
|
|
2155 | Returns the remaining time until a timer fires. If the timer is active, |
|
|
2156 | then this time is relative to the current event loop time, otherwise it's |
|
|
2157 | the timeout value currently configured. |
|
|
2158 | .Sp |
|
|
2159 | That is, after an \f(CW\*(C`ev_timer_set (w, 5, 7)\*(C'\fR, \f(CW\*(C`ev_timer_remaining\*(C'\fR returns |
|
|
2160 | \&\f(CW5\fR. When the timer is started and one second passes, \f(CW\*(C`ev_timer_remaining\*(C'\fR |
|
|
2161 | will return \f(CW4\fR. When the timer expires and is restarted, it will return |
|
|
2162 | roughly \f(CW7\fR (likely slightly less as callback invocation takes some time, |
|
|
2163 | too), and so on. |
1700 | .IP "ev_tstamp repeat [read\-write]" 4 |
2164 | .IP "ev_tstamp repeat [read\-write]" 4 |
1701 | .IX Item "ev_tstamp repeat [read-write]" |
2165 | .IX Item "ev_tstamp repeat [read-write]" |
1702 | The current \f(CW\*(C`repeat\*(C'\fR value. Will be used each time the watcher times out |
2166 | The current \f(CW\*(C`repeat\*(C'\fR value. Will be used each time the watcher times out |
1703 | or \f(CW\*(C`ev_timer_again\*(C'\fR is called, and determines the next timeout (if any), |
2167 | or \f(CW\*(C`ev_timer_again\*(C'\fR is called, and determines the next timeout (if any), |
1704 | which is also when any modifications are taken into account. |
2168 | which is also when any modifications are taken into account. |
… | |
… | |
1731 | \& } |
2195 | \& } |
1732 | \& |
2196 | \& |
1733 | \& ev_timer mytimer; |
2197 | \& ev_timer mytimer; |
1734 | \& ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */ |
2198 | \& ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */ |
1735 | \& ev_timer_again (&mytimer); /* start timer */ |
2199 | \& ev_timer_again (&mytimer); /* start timer */ |
1736 | \& ev_loop (loop, 0); |
2200 | \& ev_run (loop, 0); |
1737 | \& |
2201 | \& |
1738 | \& // and in some piece of code that gets executed on any "activity": |
2202 | \& // and in some piece of code that gets executed on any "activity": |
1739 | \& // reset the timeout to start ticking again at 10 seconds |
2203 | \& // reset the timeout to start ticking again at 10 seconds |
1740 | \& ev_timer_again (&mytimer); |
2204 | \& ev_timer_again (&mytimer); |
1741 | .Ve |
2205 | .Ve |
1742 | .ie n .Sh """ev_periodic"" \- to cron or not to cron?" |
2206 | .ie n .SS """ev_periodic"" \- to cron or not to cron?" |
1743 | .el .Sh "\f(CWev_periodic\fP \- to cron or not to cron?" |
2207 | .el .SS "\f(CWev_periodic\fP \- to cron or not to cron?" |
1744 | .IX Subsection "ev_periodic - to cron or not to cron?" |
2208 | .IX Subsection "ev_periodic - to cron or not to cron?" |
1745 | Periodic watchers are also timers of a kind, but they are very versatile |
2209 | Periodic watchers are also timers of a kind, but they are very versatile |
1746 | (and unfortunately a bit complex). |
2210 | (and unfortunately a bit complex). |
1747 | .PP |
2211 | .PP |
1748 | Unlike \f(CW\*(C`ev_timer\*(C'\fR's, they are not based on real time (or relative time) |
2212 | Unlike \f(CW\*(C`ev_timer\*(C'\fR, periodic watchers are not based on real time (or |
1749 | but on wall clock time (absolute time). You can tell a periodic watcher |
2213 | relative time, the physical time that passes) but on wall clock time |
1750 | to trigger after some specific point in time. For example, if you tell a |
2214 | (absolute time, the thing you can read on your calender or clock). The |
1751 | periodic watcher to trigger in 10 seconds (by specifying e.g. \f(CW\*(C`ev_now () |
2215 | difference is that wall clock time can run faster or slower than real |
1752 | + 10.\*(C'\fR, that is, an absolute time not a delay) and then reset your system |
2216 | time, and time jumps are not uncommon (e.g. when you adjust your |
1753 | clock to January of the previous year, then it will take more than year |
2217 | wrist-watch). |
1754 | to trigger the event (unlike an \f(CW\*(C`ev_timer\*(C'\fR, which would still trigger |
|
|
1755 | roughly 10 seconds later as it uses a relative timeout). |
|
|
1756 | .PP |
2218 | .PP |
|
|
2219 | You can tell a periodic watcher to trigger after some specific point |
|
|
2220 | in time: for example, if you tell a periodic watcher to trigger \*(L"in 10 |
|
|
2221 | seconds\*(R" (by specifying e.g. \f(CW\*(C`ev_now () + 10.\*(C'\fR, that is, an absolute time |
|
|
2222 | not a delay) and then reset your system clock to January of the previous |
|
|
2223 | year, then it will take a year or more to trigger the event (unlike an |
|
|
2224 | \&\f(CW\*(C`ev_timer\*(C'\fR, which would still trigger roughly 10 seconds after starting |
|
|
2225 | it, as it uses a relative timeout). |
|
|
2226 | .PP |
1757 | \&\f(CW\*(C`ev_periodic\*(C'\fRs can also be used to implement vastly more complex timers, |
2227 | \&\f(CW\*(C`ev_periodic\*(C'\fR watchers can also be used to implement vastly more complex |
1758 | such as triggering an event on each \*(L"midnight, local time\*(R", or other |
2228 | timers, such as triggering an event on each \*(L"midnight, local time\*(R", or |
1759 | complicated rules. |
2229 | other complicated rules. This cannot be done with \f(CW\*(C`ev_timer\*(C'\fR watchers, as |
|
|
2230 | those cannot react to time jumps. |
1760 | .PP |
2231 | .PP |
1761 | As with timers, the callback is guaranteed to be invoked only when the |
2232 | As with timers, the callback is guaranteed to be invoked only when the |
1762 | time (\f(CW\*(C`at\*(C'\fR) has passed, but if multiple periodic timers become ready |
2233 | point in time where it is supposed to trigger has passed. If multiple |
1763 | during the same loop iteration, then order of execution is undefined. |
2234 | timers become ready during the same loop iteration then the ones with |
|
|
2235 | earlier time-out values are invoked before ones with later time-out values |
|
|
2236 | (but this is no longer true when a callback calls \f(CW\*(C`ev_run\*(C'\fR recursively). |
1764 | .PP |
2237 | .PP |
1765 | \fIWatcher-Specific Functions and Data Members\fR |
2238 | \fIWatcher-Specific Functions and Data Members\fR |
1766 | .IX Subsection "Watcher-Specific Functions and Data Members" |
2239 | .IX Subsection "Watcher-Specific Functions and Data Members" |
1767 | .IP "ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)" 4 |
2240 | .IP "ev_periodic_init (ev_periodic *, callback, ev_tstamp offset, ev_tstamp interval, reschedule_cb)" 4 |
1768 | .IX Item "ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)" |
2241 | .IX Item "ev_periodic_init (ev_periodic *, callback, ev_tstamp offset, ev_tstamp interval, reschedule_cb)" |
1769 | .PD 0 |
2242 | .PD 0 |
1770 | .IP "ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)" 4 |
2243 | .IP "ev_periodic_set (ev_periodic *, ev_tstamp offset, ev_tstamp interval, reschedule_cb)" 4 |
1771 | .IX Item "ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)" |
2244 | .IX Item "ev_periodic_set (ev_periodic *, ev_tstamp offset, ev_tstamp interval, reschedule_cb)" |
1772 | .PD |
2245 | .PD |
1773 | Lots of arguments, lets sort it out... There are basically three modes of |
2246 | Lots of arguments, let's sort it out... There are basically three modes of |
1774 | operation, and we will explain them from simplest to most complex: |
2247 | operation, and we will explain them from simplest to most complex: |
1775 | .RS 4 |
2248 | .RS 4 |
1776 | .IP "\(bu" 4 |
2249 | .IP "\(bu" 4 |
1777 | absolute timer (at = time, interval = reschedule_cb = 0) |
2250 | absolute timer (offset = absolute time, interval = 0, reschedule_cb = 0) |
1778 | .Sp |
2251 | .Sp |
1779 | In this configuration the watcher triggers an event after the wall clock |
2252 | In this configuration the watcher triggers an event after the wall clock |
1780 | time \f(CW\*(C`at\*(C'\fR has passed. It will not repeat and will not adjust when a time |
2253 | time \f(CW\*(C`offset\*(C'\fR has passed. It will not repeat and will not adjust when a |
1781 | jump occurs, that is, if it is to be run at January 1st 2011 then it will |
2254 | time jump occurs, that is, if it is to be run at January 1st 2011 then it |
1782 | only run when the system clock reaches or surpasses this time. |
2255 | will be stopped and invoked when the system clock reaches or surpasses |
|
|
2256 | this point in time. |
1783 | .IP "\(bu" 4 |
2257 | .IP "\(bu" 4 |
1784 | repeating interval timer (at = offset, interval > 0, reschedule_cb = 0) |
2258 | repeating interval timer (offset = offset within interval, interval > 0, reschedule_cb = 0) |
1785 | .Sp |
2259 | .Sp |
1786 | In this mode the watcher will always be scheduled to time out at the next |
2260 | In this mode the watcher will always be scheduled to time out at the next |
1787 | \&\f(CW\*(C`at + N * interval\*(C'\fR time (for some integer N, which can also be negative) |
2261 | \&\f(CW\*(C`offset + N * interval\*(C'\fR time (for some integer N, which can also be |
1788 | and then repeat, regardless of any time jumps. |
2262 | negative) and then repeat, regardless of any time jumps. The \f(CW\*(C`offset\*(C'\fR |
|
|
2263 | argument is merely an offset into the \f(CW\*(C`interval\*(C'\fR periods. |
1789 | .Sp |
2264 | .Sp |
1790 | This can be used to create timers that do not drift with respect to the |
2265 | This can be used to create timers that do not drift with respect to the |
1791 | system clock, for example, here is a \f(CW\*(C`ev_periodic\*(C'\fR that triggers each |
2266 | system clock, for example, here is an \f(CW\*(C`ev_periodic\*(C'\fR that triggers each |
1792 | hour, on the hour: |
2267 | hour, on the hour (with respect to \s-1UTC\s0): |
1793 | .Sp |
2268 | .Sp |
1794 | .Vb 1 |
2269 | .Vb 1 |
1795 | \& ev_periodic_set (&periodic, 0., 3600., 0); |
2270 | \& ev_periodic_set (&periodic, 0., 3600., 0); |
1796 | .Ve |
2271 | .Ve |
1797 | .Sp |
2272 | .Sp |
… | |
… | |
1800 | full hour (\s-1UTC\s0), or more correctly, when the system time is evenly divisible |
2275 | full hour (\s-1UTC\s0), or more correctly, when the system time is evenly divisible |
1801 | by 3600. |
2276 | by 3600. |
1802 | .Sp |
2277 | .Sp |
1803 | Another way to think about it (for the mathematically inclined) is that |
2278 | Another way to think about it (for the mathematically inclined) is that |
1804 | \&\f(CW\*(C`ev_periodic\*(C'\fR will try to run the callback in this mode at the next possible |
2279 | \&\f(CW\*(C`ev_periodic\*(C'\fR will try to run the callback in this mode at the next possible |
1805 | time where \f(CW\*(C`time = at (mod interval)\*(C'\fR, regardless of any time jumps. |
2280 | time where \f(CW\*(C`time = offset (mod interval)\*(C'\fR, regardless of any time jumps. |
1806 | .Sp |
2281 | .Sp |
1807 | For numerical stability it is preferable that the \f(CW\*(C`at\*(C'\fR value is near |
2282 | For numerical stability it is preferable that the \f(CW\*(C`offset\*(C'\fR value is near |
1808 | \&\f(CW\*(C`ev_now ()\*(C'\fR (the current time), but there is no range requirement for |
2283 | \&\f(CW\*(C`ev_now ()\*(C'\fR (the current time), but there is no range requirement for |
1809 | this value, and in fact is often specified as zero. |
2284 | this value, and in fact is often specified as zero. |
1810 | .Sp |
2285 | .Sp |
1811 | Note also that there is an upper limit to how often a timer can fire (\s-1CPU\s0 |
2286 | Note also that there is an upper limit to how often a timer can fire (\s-1CPU\s0 |
1812 | speed for example), so if \f(CW\*(C`interval\*(C'\fR is very small then timing stability |
2287 | speed for example), so if \f(CW\*(C`interval\*(C'\fR is very small then timing stability |
1813 | will of course deteriorate. Libev itself tries to be exact to be about one |
2288 | will of course deteriorate. Libev itself tries to be exact to be about one |
1814 | millisecond (if the \s-1OS\s0 supports it and the machine is fast enough). |
2289 | millisecond (if the \s-1OS\s0 supports it and the machine is fast enough). |
1815 | .IP "\(bu" 4 |
2290 | .IP "\(bu" 4 |
1816 | manual reschedule mode (at and interval ignored, reschedule_cb = callback) |
2291 | manual reschedule mode (offset ignored, interval ignored, reschedule_cb = callback) |
1817 | .Sp |
2292 | .Sp |
1818 | In this mode the values for \f(CW\*(C`interval\*(C'\fR and \f(CW\*(C`at\*(C'\fR are both being |
2293 | In this mode the values for \f(CW\*(C`interval\*(C'\fR and \f(CW\*(C`offset\*(C'\fR are both being |
1819 | ignored. Instead, each time the periodic watcher gets scheduled, the |
2294 | ignored. Instead, each time the periodic watcher gets scheduled, the |
1820 | reschedule callback will be called with the watcher as first, and the |
2295 | reschedule callback will be called with the watcher as first, and the |
1821 | current time as second argument. |
2296 | current time as second argument. |
1822 | .Sp |
2297 | .Sp |
1823 | \&\s-1NOTE:\s0 \fIThis callback \s-1MUST\s0 \s-1NOT\s0 stop or destroy any periodic watcher, |
2298 | \&\s-1NOTE:\s0 \fIThis callback \s-1MUST\s0 \s-1NOT\s0 stop or destroy any periodic watcher, ever, |
1824 | ever, or make \s-1ANY\s0 event loop modifications whatsoever\fR. |
2299 | or make \s-1ANY\s0 other event loop modifications whatsoever, unless explicitly |
|
|
2300 | allowed by documentation here\fR. |
1825 | .Sp |
2301 | .Sp |
1826 | If you need to stop it, return \f(CW\*(C`now + 1e30\*(C'\fR (or so, fudge fudge) and stop |
2302 | If you need to stop it, return \f(CW\*(C`now + 1e30\*(C'\fR (or so, fudge fudge) and stop |
1827 | it afterwards (e.g. by starting an \f(CW\*(C`ev_prepare\*(C'\fR watcher, which is the |
2303 | it afterwards (e.g. by starting an \f(CW\*(C`ev_prepare\*(C'\fR watcher, which is the |
1828 | only event loop modification you are allowed to do). |
2304 | only event loop modification you are allowed to do). |
1829 | .Sp |
2305 | .Sp |
… | |
… | |
1860 | when you changed some parameters or the reschedule callback would return |
2336 | when you changed some parameters or the reschedule callback would return |
1861 | a different time than the last time it was called (e.g. in a crond like |
2337 | a different time than the last time it was called (e.g. in a crond like |
1862 | program when the crontabs have changed). |
2338 | program when the crontabs have changed). |
1863 | .IP "ev_tstamp ev_periodic_at (ev_periodic *)" 4 |
2339 | .IP "ev_tstamp ev_periodic_at (ev_periodic *)" 4 |
1864 | .IX Item "ev_tstamp ev_periodic_at (ev_periodic *)" |
2340 | .IX Item "ev_tstamp ev_periodic_at (ev_periodic *)" |
1865 | When active, returns the absolute time that the watcher is supposed to |
2341 | When active, returns the absolute time that the watcher is supposed |
1866 | trigger next. |
2342 | to trigger next. This is not the same as the \f(CW\*(C`offset\*(C'\fR argument to |
|
|
2343 | \&\f(CW\*(C`ev_periodic_set\*(C'\fR, but indeed works even in interval and manual |
|
|
2344 | rescheduling modes. |
1867 | .IP "ev_tstamp offset [read\-write]" 4 |
2345 | .IP "ev_tstamp offset [read\-write]" 4 |
1868 | .IX Item "ev_tstamp offset [read-write]" |
2346 | .IX Item "ev_tstamp offset [read-write]" |
1869 | When repeating, this contains the offset value, otherwise this is the |
2347 | When repeating, this contains the offset value, otherwise this is the |
1870 | absolute point in time (the \f(CW\*(C`at\*(C'\fR value passed to \f(CW\*(C`ev_periodic_set\*(C'\fR). |
2348 | absolute point in time (the \f(CW\*(C`offset\*(C'\fR value passed to \f(CW\*(C`ev_periodic_set\*(C'\fR, |
|
|
2349 | although libev might modify this value for better numerical stability). |
1871 | .Sp |
2350 | .Sp |
1872 | Can be modified any time, but changes only take effect when the periodic |
2351 | Can be modified any time, but changes only take effect when the periodic |
1873 | timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being called. |
2352 | timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being called. |
1874 | .IP "ev_tstamp interval [read\-write]" 4 |
2353 | .IP "ev_tstamp interval [read\-write]" 4 |
1875 | .IX Item "ev_tstamp interval [read-write]" |
2354 | .IX Item "ev_tstamp interval [read-write]" |
… | |
… | |
1889 | system time is divisible by 3600. The callback invocation times have |
2368 | system time is divisible by 3600. The callback invocation times have |
1890 | potentially a lot of jitter, but good long-term stability. |
2369 | potentially a lot of jitter, but good long-term stability. |
1891 | .PP |
2370 | .PP |
1892 | .Vb 5 |
2371 | .Vb 5 |
1893 | \& static void |
2372 | \& static void |
1894 | \& clock_cb (struct ev_loop *loop, ev_io *w, int revents) |
2373 | \& clock_cb (struct ev_loop *loop, ev_periodic *w, int revents) |
1895 | \& { |
2374 | \& { |
1896 | \& ... its now a full hour (UTC, or TAI or whatever your clock follows) |
2375 | \& ... its now a full hour (UTC, or TAI or whatever your clock follows) |
1897 | \& } |
2376 | \& } |
1898 | \& |
2377 | \& |
1899 | \& ev_periodic hourly_tick; |
2378 | \& ev_periodic hourly_tick; |
… | |
… | |
1921 | \& ev_periodic hourly_tick; |
2400 | \& ev_periodic hourly_tick; |
1922 | \& ev_periodic_init (&hourly_tick, clock_cb, |
2401 | \& ev_periodic_init (&hourly_tick, clock_cb, |
1923 | \& fmod (ev_now (loop), 3600.), 3600., 0); |
2402 | \& fmod (ev_now (loop), 3600.), 3600., 0); |
1924 | \& ev_periodic_start (loop, &hourly_tick); |
2403 | \& ev_periodic_start (loop, &hourly_tick); |
1925 | .Ve |
2404 | .Ve |
1926 | .ie n .Sh """ev_signal"" \- signal me when a signal gets signalled!" |
2405 | .ie n .SS """ev_signal"" \- signal me when a signal gets signalled!" |
1927 | .el .Sh "\f(CWev_signal\fP \- signal me when a signal gets signalled!" |
2406 | .el .SS "\f(CWev_signal\fP \- signal me when a signal gets signalled!" |
1928 | .IX Subsection "ev_signal - signal me when a signal gets signalled!" |
2407 | .IX Subsection "ev_signal - signal me when a signal gets signalled!" |
1929 | Signal watchers will trigger an event when the process receives a specific |
2408 | Signal watchers will trigger an event when the process receives a specific |
1930 | signal one or more times. Even though signals are very asynchronous, libev |
2409 | signal one or more times. Even though signals are very asynchronous, libev |
1931 | will try it's best to deliver signals synchronously, i.e. as part of the |
2410 | will try its best to deliver signals synchronously, i.e. as part of the |
1932 | normal event processing, like any other event. |
2411 | normal event processing, like any other event. |
1933 | .PP |
2412 | .PP |
1934 | If you want signals asynchronously, just use \f(CW\*(C`sigaction\*(C'\fR as you would |
2413 | If you want signals to be delivered truly asynchronously, just use |
1935 | do without libev and forget about sharing the signal. You can even use |
2414 | \&\f(CW\*(C`sigaction\*(C'\fR as you would do without libev and forget about sharing |
1936 | \&\f(CW\*(C`ev_async\*(C'\fR from a signal handler to synchronously wake up an event loop. |
2415 | the signal. You can even use \f(CW\*(C`ev_async\*(C'\fR from a signal handler to |
|
|
2416 | synchronously wake up an event loop. |
1937 | .PP |
2417 | .PP |
1938 | You can configure as many watchers as you like per signal. Only when the |
2418 | You can configure as many watchers as you like for the same signal, but |
|
|
2419 | only within the same loop, i.e. you can watch for \f(CW\*(C`SIGINT\*(C'\fR in your |
|
|
2420 | default loop and for \f(CW\*(C`SIGIO\*(C'\fR in another loop, but you cannot watch for |
|
|
2421 | \&\f(CW\*(C`SIGINT\*(C'\fR in both the default loop and another loop at the same time. At |
|
|
2422 | the moment, \f(CW\*(C`SIGCHLD\*(C'\fR is permanently tied to the default loop. |
|
|
2423 | .PP |
1939 | first watcher gets started will libev actually register a signal handler |
2424 | When the first watcher gets started will libev actually register something |
1940 | with the kernel (thus it coexists with your own signal handlers as long as |
2425 | with the kernel (thus it coexists with your own signal handlers as long as |
1941 | you don't register any with libev for the same signal). Similarly, when |
2426 | you don't register any with libev for the same signal). |
1942 | the last signal watcher for a signal is stopped, libev will reset the |
|
|
1943 | signal handler to \s-1SIG_DFL\s0 (regardless of what it was set to before). |
|
|
1944 | .PP |
2427 | .PP |
1945 | If possible and supported, libev will install its handlers with |
2428 | If possible and supported, libev will install its handlers with |
1946 | \&\f(CW\*(C`SA_RESTART\*(C'\fR behaviour enabled, so system calls should not be unduly |
2429 | \&\f(CW\*(C`SA_RESTART\*(C'\fR (or equivalent) behaviour enabled, so system calls should |
1947 | interrupted. If you have a problem with system calls getting interrupted by |
2430 | not be unduly interrupted. If you have a problem with system calls getting |
1948 | signals you can block all signals in an \f(CW\*(C`ev_check\*(C'\fR watcher and unblock |
2431 | interrupted by signals you can block all signals in an \f(CW\*(C`ev_check\*(C'\fR watcher |
1949 | them in an \f(CW\*(C`ev_prepare\*(C'\fR watcher. |
2432 | and unblock them in an \f(CW\*(C`ev_prepare\*(C'\fR watcher. |
|
|
2433 | .PP |
|
|
2434 | \fIThe special problem of inheritance over fork/execve/pthread_create\fR |
|
|
2435 | .IX Subsection "The special problem of inheritance over fork/execve/pthread_create" |
|
|
2436 | .PP |
|
|
2437 | Both the signal mask (\f(CW\*(C`sigprocmask\*(C'\fR) and the signal disposition |
|
|
2438 | (\f(CW\*(C`sigaction\*(C'\fR) are unspecified after starting a signal watcher (and after |
|
|
2439 | stopping it again), that is, libev might or might not block the signal, |
|
|
2440 | and might or might not set or restore the installed signal handler (but |
|
|
2441 | see \f(CW\*(C`EVFLAG_NOSIGMASK\*(C'\fR). |
|
|
2442 | .PP |
|
|
2443 | While this does not matter for the signal disposition (libev never |
|
|
2444 | sets signals to \f(CW\*(C`SIG_IGN\*(C'\fR, so handlers will be reset to \f(CW\*(C`SIG_DFL\*(C'\fR on |
|
|
2445 | \&\f(CW\*(C`execve\*(C'\fR), this matters for the signal mask: many programs do not expect |
|
|
2446 | certain signals to be blocked. |
|
|
2447 | .PP |
|
|
2448 | This means that before calling \f(CW\*(C`exec\*(C'\fR (from the child) you should reset |
|
|
2449 | the signal mask to whatever \*(L"default\*(R" you expect (all clear is a good |
|
|
2450 | choice usually). |
|
|
2451 | .PP |
|
|
2452 | The simplest way to ensure that the signal mask is reset in the child is |
|
|
2453 | to install a fork handler with \f(CW\*(C`pthread_atfork\*(C'\fR that resets it. That will |
|
|
2454 | catch fork calls done by libraries (such as the libc) as well. |
|
|
2455 | .PP |
|
|
2456 | In current versions of libev, the signal will not be blocked indefinitely |
|
|
2457 | unless you use the \f(CW\*(C`signalfd\*(C'\fR \s-1API\s0 (\f(CW\*(C`EV_SIGNALFD\*(C'\fR). While this reduces |
|
|
2458 | the window of opportunity for problems, it will not go away, as libev |
|
|
2459 | \&\fIhas\fR to modify the signal mask, at least temporarily. |
|
|
2460 | .PP |
|
|
2461 | So I can't stress this enough: \fIIf you do not reset your signal mask when |
|
|
2462 | you expect it to be empty, you have a race condition in your code\fR. This |
|
|
2463 | is not a libev-specific thing, this is true for most event libraries. |
|
|
2464 | .PP |
|
|
2465 | \fIThe special problem of threads signal handling\fR |
|
|
2466 | .IX Subsection "The special problem of threads signal handling" |
|
|
2467 | .PP |
|
|
2468 | \&\s-1POSIX\s0 threads has problematic signal handling semantics, specifically, |
|
|
2469 | a lot of functionality (sigfd, sigwait etc.) only really works if all |
|
|
2470 | threads in a process block signals, which is hard to achieve. |
|
|
2471 | .PP |
|
|
2472 | When you want to use sigwait (or mix libev signal handling with your own |
|
|
2473 | for the same signals), you can tackle this problem by globally blocking |
|
|
2474 | all signals before creating any threads (or creating them with a fully set |
|
|
2475 | sigprocmask) and also specifying the \f(CW\*(C`EVFLAG_NOSIGMASK\*(C'\fR when creating |
|
|
2476 | loops. Then designate one thread as \*(L"signal receiver thread\*(R" which handles |
|
|
2477 | these signals. You can pass on any signals that libev might be interested |
|
|
2478 | in by calling \f(CW\*(C`ev_feed_signal\*(C'\fR. |
1950 | .PP |
2479 | .PP |
1951 | \fIWatcher-Specific Functions and Data Members\fR |
2480 | \fIWatcher-Specific Functions and Data Members\fR |
1952 | .IX Subsection "Watcher-Specific Functions and Data Members" |
2481 | .IX Subsection "Watcher-Specific Functions and Data Members" |
1953 | .IP "ev_signal_init (ev_signal *, callback, int signum)" 4 |
2482 | .IP "ev_signal_init (ev_signal *, callback, int signum)" 4 |
1954 | .IX Item "ev_signal_init (ev_signal *, callback, int signum)" |
2483 | .IX Item "ev_signal_init (ev_signal *, callback, int signum)" |
… | |
… | |
1969 | .PP |
2498 | .PP |
1970 | .Vb 5 |
2499 | .Vb 5 |
1971 | \& static void |
2500 | \& static void |
1972 | \& sigint_cb (struct ev_loop *loop, ev_signal *w, int revents) |
2501 | \& sigint_cb (struct ev_loop *loop, ev_signal *w, int revents) |
1973 | \& { |
2502 | \& { |
1974 | \& ev_unloop (loop, EVUNLOOP_ALL); |
2503 | \& ev_break (loop, EVBREAK_ALL); |
1975 | \& } |
2504 | \& } |
1976 | \& |
2505 | \& |
1977 | \& ev_signal signal_watcher; |
2506 | \& ev_signal signal_watcher; |
1978 | \& ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
2507 | \& ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
1979 | \& ev_signal_start (loop, &signal_watcher); |
2508 | \& ev_signal_start (loop, &signal_watcher); |
1980 | .Ve |
2509 | .Ve |
1981 | .ie n .Sh """ev_child"" \- watch out for process status changes" |
2510 | .ie n .SS """ev_child"" \- watch out for process status changes" |
1982 | .el .Sh "\f(CWev_child\fP \- watch out for process status changes" |
2511 | .el .SS "\f(CWev_child\fP \- watch out for process status changes" |
1983 | .IX Subsection "ev_child - watch out for process status changes" |
2512 | .IX Subsection "ev_child - watch out for process status changes" |
1984 | Child watchers trigger when your process receives a \s-1SIGCHLD\s0 in response to |
2513 | Child watchers trigger when your process receives a \s-1SIGCHLD\s0 in response to |
1985 | some child status changes (most typically when a child of yours dies or |
2514 | some child status changes (most typically when a child of yours dies or |
1986 | exits). It is permissible to install a child watcher \fIafter\fR the child |
2515 | exits). It is permissible to install a child watcher \fIafter\fR the child |
1987 | has been forked (which implies it might have already exited), as long |
2516 | has been forked (which implies it might have already exited), as long |
1988 | as the event loop isn't entered (or is continued from a watcher), i.e., |
2517 | as the event loop isn't entered (or is continued from a watcher), i.e., |
1989 | forking and then immediately registering a watcher for the child is fine, |
2518 | forking and then immediately registering a watcher for the child is fine, |
1990 | but forking and registering a watcher a few event loop iterations later is |
2519 | but forking and registering a watcher a few event loop iterations later or |
1991 | not. |
2520 | in the next callback invocation is not. |
1992 | .PP |
2521 | .PP |
1993 | Only the default event loop is capable of handling signals, and therefore |
2522 | Only the default event loop is capable of handling signals, and therefore |
1994 | you can only register child watchers in the default event loop. |
2523 | you can only register child watchers in the default event loop. |
1995 | .PP |
2524 | .PP |
|
|
2525 | Due to some design glitches inside libev, child watchers will always be |
|
|
2526 | handled at maximum priority (their priority is set to \f(CW\*(C`EV_MAXPRI\*(C'\fR by |
|
|
2527 | libev) |
|
|
2528 | .PP |
1996 | \fIProcess Interaction\fR |
2529 | \fIProcess Interaction\fR |
1997 | .IX Subsection "Process Interaction" |
2530 | .IX Subsection "Process Interaction" |
1998 | .PP |
2531 | .PP |
1999 | Libev grabs \f(CW\*(C`SIGCHLD\*(C'\fR as soon as the default event loop is |
2532 | Libev grabs \f(CW\*(C`SIGCHLD\*(C'\fR as soon as the default event loop is |
2000 | initialised. This is necessary to guarantee proper behaviour even if |
2533 | initialised. This is necessary to guarantee proper behaviour even if the |
2001 | the first child watcher is started after the child exits. The occurrence |
2534 | first child watcher is started after the child exits. The occurrence |
2002 | of \f(CW\*(C`SIGCHLD\*(C'\fR is recorded asynchronously, but child reaping is done |
2535 | of \f(CW\*(C`SIGCHLD\*(C'\fR is recorded asynchronously, but child reaping is done |
2003 | synchronously as part of the event loop processing. Libev always reaps all |
2536 | synchronously as part of the event loop processing. Libev always reaps all |
2004 | children, even ones not watched. |
2537 | children, even ones not watched. |
2005 | .PP |
2538 | .PP |
2006 | \fIOverriding the Built-In Processing\fR |
2539 | \fIOverriding the Built-In Processing\fR |
… | |
… | |
2018 | .IX Subsection "Stopping the Child Watcher" |
2551 | .IX Subsection "Stopping the Child Watcher" |
2019 | .PP |
2552 | .PP |
2020 | Currently, the child watcher never gets stopped, even when the |
2553 | Currently, the child watcher never gets stopped, even when the |
2021 | child terminates, so normally one needs to stop the watcher in the |
2554 | child terminates, so normally one needs to stop the watcher in the |
2022 | callback. Future versions of libev might stop the watcher automatically |
2555 | callback. Future versions of libev might stop the watcher automatically |
2023 | when a child exit is detected. |
2556 | when a child exit is detected (calling \f(CW\*(C`ev_child_stop\*(C'\fR twice is not a |
|
|
2557 | problem). |
2024 | .PP |
2558 | .PP |
2025 | \fIWatcher-Specific Functions and Data Members\fR |
2559 | \fIWatcher-Specific Functions and Data Members\fR |
2026 | .IX Subsection "Watcher-Specific Functions and Data Members" |
2560 | .IX Subsection "Watcher-Specific Functions and Data Members" |
2027 | .IP "ev_child_init (ev_child *, callback, int pid, int trace)" 4 |
2561 | .IP "ev_child_init (ev_child *, callback, int pid, int trace)" 4 |
2028 | .IX Item "ev_child_init (ev_child *, callback, int pid, int trace)" |
2562 | .IX Item "ev_child_init (ev_child *, callback, int pid, int trace)" |
… | |
… | |
2078 | \& { |
2612 | \& { |
2079 | \& ev_child_init (&cw, child_cb, pid, 0); |
2613 | \& ev_child_init (&cw, child_cb, pid, 0); |
2080 | \& ev_child_start (EV_DEFAULT_ &cw); |
2614 | \& ev_child_start (EV_DEFAULT_ &cw); |
2081 | \& } |
2615 | \& } |
2082 | .Ve |
2616 | .Ve |
2083 | .ie n .Sh """ev_stat"" \- did the file attributes just change?" |
2617 | .ie n .SS """ev_stat"" \- did the file attributes just change?" |
2084 | .el .Sh "\f(CWev_stat\fP \- did the file attributes just change?" |
2618 | .el .SS "\f(CWev_stat\fP \- did the file attributes just change?" |
2085 | .IX Subsection "ev_stat - did the file attributes just change?" |
2619 | .IX Subsection "ev_stat - did the file attributes just change?" |
2086 | This watches a file system path for attribute changes. That is, it calls |
2620 | This watches a file system path for attribute changes. That is, it calls |
2087 | \&\f(CW\*(C`stat\*(C'\fR on that path in regular intervals (or when the \s-1OS\s0 says it changed) |
2621 | \&\f(CW\*(C`stat\*(C'\fR on that path in regular intervals (or when the \s-1OS\s0 says it changed) |
2088 | and sees if it changed compared to the last time, invoking the callback if |
2622 | and sees if it changed compared to the last time, invoking the callback if |
2089 | it did. |
2623 | it did. |
… | |
… | |
2164 | the process. The exception are \f(CW\*(C`ev_stat\*(C'\fR watchers \- those call \f(CW\*(C`stat |
2698 | the process. The exception are \f(CW\*(C`ev_stat\*(C'\fR watchers \- those call \f(CW\*(C`stat |
2165 | ()\*(C'\fR, which is a synchronous operation. |
2699 | ()\*(C'\fR, which is a synchronous operation. |
2166 | .PP |
2700 | .PP |
2167 | For local paths, this usually doesn't matter: unless the system is very |
2701 | For local paths, this usually doesn't matter: unless the system is very |
2168 | busy or the intervals between stat's are large, a stat call will be fast, |
2702 | busy or the intervals between stat's are large, a stat call will be fast, |
2169 | as the path data is suually in memory already (except when starting the |
2703 | as the path data is usually in memory already (except when starting the |
2170 | watcher). |
2704 | watcher). |
2171 | .PP |
2705 | .PP |
2172 | For networked file systems, calling \f(CW\*(C`stat ()\*(C'\fR can block an indefinite |
2706 | For networked file systems, calling \f(CW\*(C`stat ()\*(C'\fR can block an indefinite |
2173 | time due to network issues, and even under good conditions, a stat call |
2707 | time due to network issues, and even under good conditions, a stat call |
2174 | often takes multiple milliseconds. |
2708 | often takes multiple milliseconds. |
… | |
… | |
2303 | \& ... |
2837 | \& ... |
2304 | \& ev_stat_init (&passwd, stat_cb, "/etc/passwd", 0.); |
2838 | \& ev_stat_init (&passwd, stat_cb, "/etc/passwd", 0.); |
2305 | \& ev_stat_start (loop, &passwd); |
2839 | \& ev_stat_start (loop, &passwd); |
2306 | \& ev_timer_init (&timer, timer_cb, 0., 1.02); |
2840 | \& ev_timer_init (&timer, timer_cb, 0., 1.02); |
2307 | .Ve |
2841 | .Ve |
2308 | .ie n .Sh """ev_idle"" \- when you've got nothing better to do..." |
2842 | .ie n .SS """ev_idle"" \- when you've got nothing better to do..." |
2309 | .el .Sh "\f(CWev_idle\fP \- when you've got nothing better to do..." |
2843 | .el .SS "\f(CWev_idle\fP \- when you've got nothing better to do..." |
2310 | .IX Subsection "ev_idle - when you've got nothing better to do..." |
2844 | .IX Subsection "ev_idle - when you've got nothing better to do..." |
2311 | Idle watchers trigger events when no other events of the same or higher |
2845 | Idle watchers trigger events when no other events of the same or higher |
2312 | priority are pending (prepare, check and other idle watchers do not count |
2846 | priority are pending (prepare, check and other idle watchers do not count |
2313 | as receiving \*(L"events\*(R"). |
2847 | as receiving \*(L"events\*(R"). |
2314 | .PP |
2848 | .PP |
… | |
… | |
2327 | \&\*(L"pseudo-background processing\*(R", or delay processing stuff to after the |
2861 | \&\*(L"pseudo-background processing\*(R", or delay processing stuff to after the |
2328 | event loop has handled all outstanding events. |
2862 | event loop has handled all outstanding events. |
2329 | .PP |
2863 | .PP |
2330 | \fIWatcher-Specific Functions and Data Members\fR |
2864 | \fIWatcher-Specific Functions and Data Members\fR |
2331 | .IX Subsection "Watcher-Specific Functions and Data Members" |
2865 | .IX Subsection "Watcher-Specific Functions and Data Members" |
2332 | .IP "ev_idle_init (ev_signal *, callback)" 4 |
2866 | .IP "ev_idle_init (ev_idle *, callback)" 4 |
2333 | .IX Item "ev_idle_init (ev_signal *, callback)" |
2867 | .IX Item "ev_idle_init (ev_idle *, callback)" |
2334 | Initialises and configures the idle watcher \- it has no parameters of any |
2868 | Initialises and configures the idle watcher \- it has no parameters of any |
2335 | kind. There is a \f(CW\*(C`ev_idle_set\*(C'\fR macro, but using it is utterly pointless, |
2869 | kind. There is a \f(CW\*(C`ev_idle_set\*(C'\fR macro, but using it is utterly pointless, |
2336 | believe me. |
2870 | believe me. |
2337 | .PP |
2871 | .PP |
2338 | \fIExamples\fR |
2872 | \fIExamples\fR |
… | |
… | |
2350 | \& // no longer anything immediate to do. |
2884 | \& // no longer anything immediate to do. |
2351 | \& } |
2885 | \& } |
2352 | \& |
2886 | \& |
2353 | \& ev_idle *idle_watcher = malloc (sizeof (ev_idle)); |
2887 | \& ev_idle *idle_watcher = malloc (sizeof (ev_idle)); |
2354 | \& ev_idle_init (idle_watcher, idle_cb); |
2888 | \& ev_idle_init (idle_watcher, idle_cb); |
2355 | \& ev_idle_start (loop, idle_cb); |
2889 | \& ev_idle_start (loop, idle_watcher); |
2356 | .Ve |
2890 | .Ve |
2357 | .ie n .Sh """ev_prepare""\fP and \f(CW""ev_check"" \- customise your event loop!" |
2891 | .ie n .SS """ev_prepare"" and ""ev_check"" \- customise your event loop!" |
2358 | .el .Sh "\f(CWev_prepare\fP and \f(CWev_check\fP \- customise your event loop!" |
2892 | .el .SS "\f(CWev_prepare\fP and \f(CWev_check\fP \- customise your event loop!" |
2359 | .IX Subsection "ev_prepare and ev_check - customise your event loop!" |
2893 | .IX Subsection "ev_prepare and ev_check - customise your event loop!" |
2360 | Prepare and check watchers are usually (but not always) used in pairs: |
2894 | Prepare and check watchers are usually (but not always) used in pairs: |
2361 | prepare watchers get invoked before the process blocks and check watchers |
2895 | prepare watchers get invoked before the process blocks and check watchers |
2362 | afterwards. |
2896 | afterwards. |
2363 | .PP |
2897 | .PP |
2364 | You \fImust not\fR call \f(CW\*(C`ev_loop\*(C'\fR or similar functions that enter |
2898 | You \fImust not\fR call \f(CW\*(C`ev_run\*(C'\fR or similar functions that enter |
2365 | the current event loop from either \f(CW\*(C`ev_prepare\*(C'\fR or \f(CW\*(C`ev_check\*(C'\fR |
2899 | the current event loop from either \f(CW\*(C`ev_prepare\*(C'\fR or \f(CW\*(C`ev_check\*(C'\fR |
2366 | watchers. Other loops than the current one are fine, however. The |
2900 | watchers. Other loops than the current one are fine, however. The |
2367 | rationale behind this is that you do not need to check for recursion in |
2901 | rationale behind this is that you do not need to check for recursion in |
2368 | those watchers, i.e. the sequence will always be \f(CW\*(C`ev_prepare\*(C'\fR, blocking, |
2902 | those watchers, i.e. the sequence will always be \f(CW\*(C`ev_prepare\*(C'\fR, blocking, |
2369 | \&\f(CW\*(C`ev_check\*(C'\fR so if you have one watcher of each kind they will always be |
2903 | \&\f(CW\*(C`ev_check\*(C'\fR so if you have one watcher of each kind they will always be |
… | |
… | |
2453 | \& struct pollfd fds [nfd]; |
2987 | \& struct pollfd fds [nfd]; |
2454 | \& // actual code will need to loop here and realloc etc. |
2988 | \& // actual code will need to loop here and realloc etc. |
2455 | \& adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
2989 | \& adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
2456 | \& |
2990 | \& |
2457 | \& /* the callback is illegal, but won\*(Aqt be called as we stop during check */ |
2991 | \& /* the callback is illegal, but won\*(Aqt be called as we stop during check */ |
2458 | \& ev_timer_init (&tw, 0, timeout * 1e\-3); |
2992 | \& ev_timer_init (&tw, 0, timeout * 1e\-3, 0.); |
2459 | \& ev_timer_start (loop, &tw); |
2993 | \& ev_timer_start (loop, &tw); |
2460 | \& |
2994 | \& |
2461 | \& // create one ev_io per pollfd |
2995 | \& // create one ev_io per pollfd |
2462 | \& for (int i = 0; i < nfd; ++i) |
2996 | \& for (int i = 0; i < nfd; ++i) |
2463 | \& { |
2997 | \& { |
… | |
… | |
2541 | \& |
3075 | \& |
2542 | \& if (timeout >= 0) |
3076 | \& if (timeout >= 0) |
2543 | \& // create/start timer |
3077 | \& // create/start timer |
2544 | \& |
3078 | \& |
2545 | \& // poll |
3079 | \& // poll |
2546 | \& ev_loop (EV_A_ 0); |
3080 | \& ev_run (EV_A_ 0); |
2547 | \& |
3081 | \& |
2548 | \& // stop timer again |
3082 | \& // stop timer again |
2549 | \& if (timeout >= 0) |
3083 | \& if (timeout >= 0) |
2550 | \& ev_timer_stop (EV_A_ &to); |
3084 | \& ev_timer_stop (EV_A_ &to); |
2551 | \& |
3085 | \& |
… | |
… | |
2554 | \& ev_io_stop (EV_A_ iow [n]); |
3088 | \& ev_io_stop (EV_A_ iow [n]); |
2555 | \& |
3089 | \& |
2556 | \& return got_events; |
3090 | \& return got_events; |
2557 | \& } |
3091 | \& } |
2558 | .Ve |
3092 | .Ve |
2559 | .ie n .Sh """ev_embed"" \- when one backend isn't enough..." |
3093 | .ie n .SS """ev_embed"" \- when one backend isn't enough..." |
2560 | .el .Sh "\f(CWev_embed\fP \- when one backend isn't enough..." |
3094 | .el .SS "\f(CWev_embed\fP \- when one backend isn't enough..." |
2561 | .IX Subsection "ev_embed - when one backend isn't enough..." |
3095 | .IX Subsection "ev_embed - when one backend isn't enough..." |
2562 | This is a rather advanced watcher type that lets you embed one event loop |
3096 | This is a rather advanced watcher type that lets you embed one event loop |
2563 | into another (currently only \f(CW\*(C`ev_io\*(C'\fR events are supported in the embedded |
3097 | into another (currently only \f(CW\*(C`ev_io\*(C'\fR events are supported in the embedded |
2564 | loop, other types of watchers might be handled in a delayed or incorrect |
3098 | loop, other types of watchers might be handled in a delayed or incorrect |
2565 | fashion and must not be used). |
3099 | fashion and must not be used). |
… | |
… | |
2580 | some fds have to be watched and handled very quickly (with low latency), |
3114 | some fds have to be watched and handled very quickly (with low latency), |
2581 | and even priorities and idle watchers might have too much overhead. In |
3115 | and even priorities and idle watchers might have too much overhead. In |
2582 | this case you would put all the high priority stuff in one loop and all |
3116 | this case you would put all the high priority stuff in one loop and all |
2583 | the rest in a second one, and embed the second one in the first. |
3117 | the rest in a second one, and embed the second one in the first. |
2584 | .PP |
3118 | .PP |
2585 | As long as the watcher is active, the callback will be invoked every time |
3119 | As long as the watcher is active, the callback will be invoked every |
2586 | there might be events pending in the embedded loop. The callback must then |
3120 | time there might be events pending in the embedded loop. The callback |
2587 | call \f(CW\*(C`ev_embed_sweep (mainloop, watcher)\*(C'\fR to make a single sweep and invoke |
3121 | must then call \f(CW\*(C`ev_embed_sweep (mainloop, watcher)\*(C'\fR to make a single |
2588 | their callbacks (you could also start an idle watcher to give the embedded |
3122 | sweep and invoke their callbacks (the callback doesn't need to invoke the |
2589 | loop strictly lower priority for example). You can also set the callback |
3123 | \&\f(CW\*(C`ev_embed_sweep\*(C'\fR function directly, it could also start an idle watcher |
2590 | to \f(CW0\fR, in which case the embed watcher will automatically execute the |
3124 | to give the embedded loop strictly lower priority for example). |
2591 | embedded loop sweep. |
|
|
2592 | .PP |
3125 | .PP |
2593 | As long as the watcher is started it will automatically handle events. The |
3126 | You can also set the callback to \f(CW0\fR, in which case the embed watcher |
2594 | callback will be invoked whenever some events have been handled. You can |
3127 | will automatically execute the embedded loop sweep whenever necessary. |
2595 | set the callback to \f(CW0\fR to avoid having to specify one if you are not |
|
|
2596 | interested in that. |
|
|
2597 | .PP |
3128 | .PP |
2598 | Also, there have not currently been made special provisions for forking: |
3129 | Fork detection will be handled transparently while the \f(CW\*(C`ev_embed\*(C'\fR watcher |
2599 | when you fork, you not only have to call \f(CW\*(C`ev_loop_fork\*(C'\fR on both loops, |
3130 | is active, i.e., the embedded loop will automatically be forked when the |
2600 | but you will also have to stop and restart any \f(CW\*(C`ev_embed\*(C'\fR watchers |
3131 | embedding loop forks. In other cases, the user is responsible for calling |
2601 | yourself \- but you can use a fork watcher to handle this automatically, |
3132 | \&\f(CW\*(C`ev_loop_fork\*(C'\fR on the embedded loop. |
2602 | and future versions of libev might do just that. |
|
|
2603 | .PP |
3133 | .PP |
2604 | Unfortunately, not all backends are embeddable: only the ones returned by |
3134 | Unfortunately, not all backends are embeddable: only the ones returned by |
2605 | \&\f(CW\*(C`ev_embeddable_backends\*(C'\fR are, which, unfortunately, does not include any |
3135 | \&\f(CW\*(C`ev_embeddable_backends\*(C'\fR are, which, unfortunately, does not include any |
2606 | portable one. |
3136 | portable one. |
2607 | .PP |
3137 | .PP |
… | |
… | |
2633 | to invoke it (it will continue to be called until the sweep has been done, |
3163 | to invoke it (it will continue to be called until the sweep has been done, |
2634 | if you do not want that, you need to temporarily stop the embed watcher). |
3164 | if you do not want that, you need to temporarily stop the embed watcher). |
2635 | .IP "ev_embed_sweep (loop, ev_embed *)" 4 |
3165 | .IP "ev_embed_sweep (loop, ev_embed *)" 4 |
2636 | .IX Item "ev_embed_sweep (loop, ev_embed *)" |
3166 | .IX Item "ev_embed_sweep (loop, ev_embed *)" |
2637 | Make a single, non-blocking sweep over the embedded loop. This works |
3167 | Make a single, non-blocking sweep over the embedded loop. This works |
2638 | similarly to \f(CW\*(C`ev_loop (embedded_loop, EVLOOP_NONBLOCK)\*(C'\fR, but in the most |
3168 | similarly to \f(CW\*(C`ev_run (embedded_loop, EVRUN_NOWAIT)\*(C'\fR, but in the most |
2639 | appropriate way for embedded loops. |
3169 | appropriate way for embedded loops. |
2640 | .IP "struct ev_loop *other [read\-only]" 4 |
3170 | .IP "struct ev_loop *other [read\-only]" 4 |
2641 | .IX Item "struct ev_loop *other [read-only]" |
3171 | .IX Item "struct ev_loop *other [read-only]" |
2642 | The embedded event loop. |
3172 | The embedded event loop. |
2643 | .PP |
3173 | .PP |
… | |
… | |
2691 | \& if (!loop_socket) |
3221 | \& if (!loop_socket) |
2692 | \& loop_socket = loop; |
3222 | \& loop_socket = loop; |
2693 | \& |
3223 | \& |
2694 | \& // now use loop_socket for all sockets, and loop for everything else |
3224 | \& // now use loop_socket for all sockets, and loop for everything else |
2695 | .Ve |
3225 | .Ve |
2696 | .ie n .Sh """ev_fork"" \- the audacity to resume the event loop after a fork" |
3226 | .ie n .SS """ev_fork"" \- the audacity to resume the event loop after a fork" |
2697 | .el .Sh "\f(CWev_fork\fP \- the audacity to resume the event loop after a fork" |
3227 | .el .SS "\f(CWev_fork\fP \- the audacity to resume the event loop after a fork" |
2698 | .IX Subsection "ev_fork - the audacity to resume the event loop after a fork" |
3228 | .IX Subsection "ev_fork - the audacity to resume the event loop after a fork" |
2699 | Fork watchers are called when a \f(CW\*(C`fork ()\*(C'\fR was detected (usually because |
3229 | Fork watchers are called when a \f(CW\*(C`fork ()\*(C'\fR was detected (usually because |
2700 | whoever is a good citizen cared to tell libev about it by calling |
3230 | whoever is a good citizen cared to tell libev about it by calling |
2701 | \&\f(CW\*(C`ev_default_fork\*(C'\fR or \f(CW\*(C`ev_loop_fork\*(C'\fR). The invocation is done before the |
3231 | \&\f(CW\*(C`ev_default_fork\*(C'\fR or \f(CW\*(C`ev_loop_fork\*(C'\fR). The invocation is done before the |
2702 | event loop blocks next and before \f(CW\*(C`ev_check\*(C'\fR watchers are being called, |
3232 | event loop blocks next and before \f(CW\*(C`ev_check\*(C'\fR watchers are being called, |
2703 | and only in the child after the fork. If whoever good citizen calling |
3233 | and only in the child after the fork. If whoever good citizen calling |
2704 | \&\f(CW\*(C`ev_default_fork\*(C'\fR cheats and calls it in the wrong process, the fork |
3234 | \&\f(CW\*(C`ev_default_fork\*(C'\fR cheats and calls it in the wrong process, the fork |
2705 | handlers will be invoked, too, of course. |
3235 | handlers will be invoked, too, of course. |
2706 | .PP |
3236 | .PP |
|
|
3237 | \fIThe special problem of life after fork \- how is it possible?\fR |
|
|
3238 | .IX Subsection "The special problem of life after fork - how is it possible?" |
|
|
3239 | .PP |
|
|
3240 | Most uses of \f(CW\*(C`fork()\*(C'\fR consist of forking, then some simple calls to set |
|
|
3241 | up/change the process environment, followed by a call to \f(CW\*(C`exec()\*(C'\fR. This |
|
|
3242 | sequence should be handled by libev without any problems. |
|
|
3243 | .PP |
|
|
3244 | This changes when the application actually wants to do event handling |
|
|
3245 | in the child, or both parent in child, in effect \*(L"continuing\*(R" after the |
|
|
3246 | fork. |
|
|
3247 | .PP |
|
|
3248 | The default mode of operation (for libev, with application help to detect |
|
|
3249 | forks) is to duplicate all the state in the child, as would be expected |
|
|
3250 | when \fIeither\fR the parent \fIor\fR the child process continues. |
|
|
3251 | .PP |
|
|
3252 | When both processes want to continue using libev, then this is usually the |
|
|
3253 | wrong result. In that case, usually one process (typically the parent) is |
|
|
3254 | supposed to continue with all watchers in place as before, while the other |
|
|
3255 | process typically wants to start fresh, i.e. without any active watchers. |
|
|
3256 | .PP |
|
|
3257 | The cleanest and most efficient way to achieve that with libev is to |
|
|
3258 | simply create a new event loop, which of course will be \*(L"empty\*(R", and |
|
|
3259 | use that for new watchers. This has the advantage of not touching more |
|
|
3260 | memory than necessary, and thus avoiding the copy-on-write, and the |
|
|
3261 | disadvantage of having to use multiple event loops (which do not support |
|
|
3262 | signal watchers). |
|
|
3263 | .PP |
|
|
3264 | When this is not possible, or you want to use the default loop for |
|
|
3265 | other reasons, then in the process that wants to start \*(L"fresh\*(R", call |
|
|
3266 | \&\f(CW\*(C`ev_loop_destroy (EV_DEFAULT)\*(C'\fR followed by \f(CW\*(C`ev_default_loop (...)\*(C'\fR. |
|
|
3267 | Destroying the default loop will \*(L"orphan\*(R" (not stop) all registered |
|
|
3268 | watchers, so you have to be careful not to execute code that modifies |
|
|
3269 | those watchers. Note also that in that case, you have to re-register any |
|
|
3270 | signal watchers. |
|
|
3271 | .PP |
2707 | \fIWatcher-Specific Functions and Data Members\fR |
3272 | \fIWatcher-Specific Functions and Data Members\fR |
2708 | .IX Subsection "Watcher-Specific Functions and Data Members" |
3273 | .IX Subsection "Watcher-Specific Functions and Data Members" |
2709 | .IP "ev_fork_init (ev_signal *, callback)" 4 |
3274 | .IP "ev_fork_init (ev_fork *, callback)" 4 |
2710 | .IX Item "ev_fork_init (ev_signal *, callback)" |
3275 | .IX Item "ev_fork_init (ev_fork *, callback)" |
2711 | Initialises and configures the fork watcher \- it has no parameters of any |
3276 | Initialises and configures the fork watcher \- it has no parameters of any |
2712 | kind. There is a \f(CW\*(C`ev_fork_set\*(C'\fR macro, but using it is utterly pointless, |
3277 | kind. There is a \f(CW\*(C`ev_fork_set\*(C'\fR macro, but using it is utterly pointless, |
2713 | believe me. |
3278 | really. |
|
|
3279 | .ie n .SS """ev_cleanup"" \- even the best things end" |
|
|
3280 | .el .SS "\f(CWev_cleanup\fP \- even the best things end" |
|
|
3281 | .IX Subsection "ev_cleanup - even the best things end" |
|
|
3282 | Cleanup watchers are called just before the event loop is being destroyed |
|
|
3283 | by a call to \f(CW\*(C`ev_loop_destroy\*(C'\fR. |
|
|
3284 | .PP |
|
|
3285 | While there is no guarantee that the event loop gets destroyed, cleanup |
|
|
3286 | watchers provide a convenient method to install cleanup hooks for your |
|
|
3287 | program, worker threads and so on \- you just to make sure to destroy the |
|
|
3288 | loop when you want them to be invoked. |
|
|
3289 | .PP |
|
|
3290 | Cleanup watchers are invoked in the same way as any other watcher. Unlike |
|
|
3291 | all other watchers, they do not keep a reference to the event loop (which |
|
|
3292 | makes a lot of sense if you think about it). Like all other watchers, you |
|
|
3293 | can call libev functions in the callback, except \f(CW\*(C`ev_cleanup_start\*(C'\fR. |
|
|
3294 | .PP |
|
|
3295 | \fIWatcher-Specific Functions and Data Members\fR |
|
|
3296 | .IX Subsection "Watcher-Specific Functions and Data Members" |
|
|
3297 | .IP "ev_cleanup_init (ev_cleanup *, callback)" 4 |
|
|
3298 | .IX Item "ev_cleanup_init (ev_cleanup *, callback)" |
|
|
3299 | Initialises and configures the cleanup watcher \- it has no parameters of |
|
|
3300 | any kind. There is a \f(CW\*(C`ev_cleanup_set\*(C'\fR macro, but using it is utterly |
|
|
3301 | pointless, I assure you. |
|
|
3302 | .PP |
|
|
3303 | Example: Register an atexit handler to destroy the default loop, so any |
|
|
3304 | cleanup functions are called. |
|
|
3305 | .PP |
|
|
3306 | .Vb 5 |
|
|
3307 | \& static void |
|
|
3308 | \& program_exits (void) |
|
|
3309 | \& { |
|
|
3310 | \& ev_loop_destroy (EV_DEFAULT_UC); |
|
|
3311 | \& } |
|
|
3312 | \& |
|
|
3313 | \& ... |
|
|
3314 | \& atexit (program_exits); |
|
|
3315 | .Ve |
2714 | .ie n .Sh """ev_async"" \- how to wake up another event loop" |
3316 | .ie n .SS """ev_async"" \- how to wake up an event loop" |
2715 | .el .Sh "\f(CWev_async\fP \- how to wake up another event loop" |
3317 | .el .SS "\f(CWev_async\fP \- how to wake up an event loop" |
2716 | .IX Subsection "ev_async - how to wake up another event loop" |
3318 | .IX Subsection "ev_async - how to wake up an event loop" |
2717 | In general, you cannot use an \f(CW\*(C`ev_loop\*(C'\fR from multiple threads or other |
3319 | In general, you cannot use an \f(CW\*(C`ev_loop\*(C'\fR from multiple threads or other |
2718 | asynchronous sources such as signal handlers (as opposed to multiple event |
3320 | asynchronous sources such as signal handlers (as opposed to multiple event |
2719 | loops \- those are of course safe to use in different threads). |
3321 | loops \- those are of course safe to use in different threads). |
2720 | .PP |
3322 | .PP |
2721 | Sometimes, however, you need to wake up another event loop you do not |
3323 | Sometimes, however, you need to wake up an event loop you do not control, |
2722 | control, for example because it belongs to another thread. This is what |
3324 | for example because it belongs to another thread. This is what \f(CW\*(C`ev_async\*(C'\fR |
2723 | \&\f(CW\*(C`ev_async\*(C'\fR watchers do: as long as the \f(CW\*(C`ev_async\*(C'\fR watcher is active, you |
3325 | watchers do: as long as the \f(CW\*(C`ev_async\*(C'\fR watcher is active, you can signal |
2724 | can signal it by calling \f(CW\*(C`ev_async_send\*(C'\fR, which is thread\- and signal |
3326 | it by calling \f(CW\*(C`ev_async_send\*(C'\fR, which is thread\- and signal safe. |
2725 | safe. |
|
|
2726 | .PP |
3327 | .PP |
2727 | This functionality is very similar to \f(CW\*(C`ev_signal\*(C'\fR watchers, as signals, |
3328 | This functionality is very similar to \f(CW\*(C`ev_signal\*(C'\fR watchers, as signals, |
2728 | too, are asynchronous in nature, and signals, too, will be compressed |
3329 | too, are asynchronous in nature, and signals, too, will be compressed |
2729 | (i.e. the number of callback invocations may be less than the number of |
3330 | (i.e. the number of callback invocations may be less than the number of |
2730 | \&\f(CW\*(C`ev_async_sent\*(C'\fR calls). |
3331 | \&\f(CW\*(C`ev_async_sent\*(C'\fR calls). In fact, you could use signal watchers as a kind |
|
|
3332 | of \*(L"global async watchers\*(R" by using a watcher on an otherwise unused |
|
|
3333 | signal, and \f(CW\*(C`ev_feed_signal\*(C'\fR to signal this watcher from another thread, |
|
|
3334 | even without knowing which loop owns the signal. |
2731 | .PP |
3335 | .PP |
2732 | Unlike \f(CW\*(C`ev_signal\*(C'\fR watchers, \f(CW\*(C`ev_async\*(C'\fR works with any event loop, not |
3336 | Unlike \f(CW\*(C`ev_signal\*(C'\fR watchers, \f(CW\*(C`ev_async\*(C'\fR works with any event loop, not |
2733 | just the default loop. |
3337 | just the default loop. |
2734 | .PP |
3338 | .PP |
2735 | \fIQueueing\fR |
3339 | \fIQueueing\fR |
2736 | .IX Subsection "Queueing" |
3340 | .IX Subsection "Queueing" |
2737 | .PP |
3341 | .PP |
2738 | \&\f(CW\*(C`ev_async\*(C'\fR does not support queueing of data in any way. The reason |
3342 | \&\f(CW\*(C`ev_async\*(C'\fR does not support queueing of data in any way. The reason |
2739 | is that the author does not know of a simple (or any) algorithm for a |
3343 | is that the author does not know of a simple (or any) algorithm for a |
2740 | multiple-writer-single-reader queue that works in all cases and doesn't |
3344 | multiple-writer-single-reader queue that works in all cases and doesn't |
2741 | need elaborate support such as pthreads. |
3345 | need elaborate support such as pthreads or unportable memory access |
|
|
3346 | semantics. |
2742 | .PP |
3347 | .PP |
2743 | That means that if you want to queue data, you have to provide your own |
3348 | That means that if you want to queue data, you have to provide your own |
2744 | queue. But at least I can tell you how to implement locking around your |
3349 | queue. But at least I can tell you how to implement locking around your |
2745 | queue: |
3350 | queue: |
2746 | .IP "queueing from a signal handler context" 4 |
3351 | .IP "queueing from a signal handler context" 4 |
… | |
… | |
2824 | kind. There is a \f(CW\*(C`ev_async_set\*(C'\fR macro, but using it is utterly pointless, |
3429 | kind. There is a \f(CW\*(C`ev_async_set\*(C'\fR macro, but using it is utterly pointless, |
2825 | trust me. |
3430 | trust me. |
2826 | .IP "ev_async_send (loop, ev_async *)" 4 |
3431 | .IP "ev_async_send (loop, ev_async *)" 4 |
2827 | .IX Item "ev_async_send (loop, ev_async *)" |
3432 | .IX Item "ev_async_send (loop, ev_async *)" |
2828 | Sends/signals/activates the given \f(CW\*(C`ev_async\*(C'\fR watcher, that is, feeds |
3433 | Sends/signals/activates the given \f(CW\*(C`ev_async\*(C'\fR watcher, that is, feeds |
2829 | an \f(CW\*(C`EV_ASYNC\*(C'\fR event on the watcher into the event loop. Unlike |
3434 | an \f(CW\*(C`EV_ASYNC\*(C'\fR event on the watcher into the event loop, and instantly |
|
|
3435 | returns. |
|
|
3436 | .Sp |
2830 | \&\f(CW\*(C`ev_feed_event\*(C'\fR, this call is safe to do from other threads, signal or |
3437 | Unlike \f(CW\*(C`ev_feed_event\*(C'\fR, this call is safe to do from other threads, |
2831 | similar contexts (see the discussion of \f(CW\*(C`EV_ATOMIC_T\*(C'\fR in the embedding |
3438 | signal or similar contexts (see the discussion of \f(CW\*(C`EV_ATOMIC_T\*(C'\fR in the |
2832 | section below on what exactly this means). |
3439 | embedding section below on what exactly this means). |
2833 | .Sp |
3440 | .Sp |
|
|
3441 | Note that, as with other watchers in libev, multiple events might get |
|
|
3442 | compressed into a single callback invocation (another way to look at this |
|
|
3443 | is that \f(CW\*(C`ev_async\*(C'\fR watchers are level-triggered, set on \f(CW\*(C`ev_async_send\*(C'\fR, |
|
|
3444 | reset when the event loop detects that). |
|
|
3445 | .Sp |
2834 | This call incurs the overhead of a system call only once per loop iteration, |
3446 | This call incurs the overhead of a system call only once per event loop |
2835 | so while the overhead might be noticeable, it doesn't apply to repeated |
3447 | iteration, so while the overhead might be noticeable, it doesn't apply to |
2836 | calls to \f(CW\*(C`ev_async_send\*(C'\fR. |
3448 | repeated calls to \f(CW\*(C`ev_async_send\*(C'\fR for the same event loop. |
2837 | .IP "bool = ev_async_pending (ev_async *)" 4 |
3449 | .IP "bool = ev_async_pending (ev_async *)" 4 |
2838 | .IX Item "bool = ev_async_pending (ev_async *)" |
3450 | .IX Item "bool = ev_async_pending (ev_async *)" |
2839 | Returns a non-zero value when \f(CW\*(C`ev_async_send\*(C'\fR has been called on the |
3451 | Returns a non-zero value when \f(CW\*(C`ev_async_send\*(C'\fR has been called on the |
2840 | watcher but the event has not yet been processed (or even noted) by the |
3452 | watcher but the event has not yet been processed (or even noted) by the |
2841 | event loop. |
3453 | event loop. |
… | |
… | |
2843 | \&\f(CW\*(C`ev_async_send\*(C'\fR sets a flag in the watcher and wakes up the loop. When |
3455 | \&\f(CW\*(C`ev_async_send\*(C'\fR sets a flag in the watcher and wakes up the loop. When |
2844 | the loop iterates next and checks for the watcher to have become active, |
3456 | the loop iterates next and checks for the watcher to have become active, |
2845 | it will reset the flag again. \f(CW\*(C`ev_async_pending\*(C'\fR can be used to very |
3457 | it will reset the flag again. \f(CW\*(C`ev_async_pending\*(C'\fR can be used to very |
2846 | quickly check whether invoking the loop might be a good idea. |
3458 | quickly check whether invoking the loop might be a good idea. |
2847 | .Sp |
3459 | .Sp |
2848 | Not that this does \fInot\fR check whether the watcher itself is pending, only |
3460 | Not that this does \fInot\fR check whether the watcher itself is pending, |
2849 | whether it has been requested to make this watcher pending. |
3461 | only whether it has been requested to make this watcher pending: there |
|
|
3462 | is a time window between the event loop checking and resetting the async |
|
|
3463 | notification, and the callback being invoked. |
2850 | .SH "OTHER FUNCTIONS" |
3464 | .SH "OTHER FUNCTIONS" |
2851 | .IX Header "OTHER FUNCTIONS" |
3465 | .IX Header "OTHER FUNCTIONS" |
2852 | There are some other functions of possible interest. Described. Here. Now. |
3466 | There are some other functions of possible interest. Described. Here. Now. |
2853 | .IP "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" 4 |
3467 | .IP "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" 4 |
2854 | .IX Item "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" |
3468 | .IX Item "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" |
… | |
… | |
2864 | .Sp |
3478 | .Sp |
2865 | If \f(CW\*(C`timeout\*(C'\fR is less than 0, then no timeout watcher will be |
3479 | If \f(CW\*(C`timeout\*(C'\fR is less than 0, then no timeout watcher will be |
2866 | started. Otherwise an \f(CW\*(C`ev_timer\*(C'\fR watcher with after = \f(CW\*(C`timeout\*(C'\fR (and |
3480 | started. Otherwise an \f(CW\*(C`ev_timer\*(C'\fR watcher with after = \f(CW\*(C`timeout\*(C'\fR (and |
2867 | repeat = 0) will be started. \f(CW0\fR is a valid timeout. |
3481 | repeat = 0) will be started. \f(CW0\fR is a valid timeout. |
2868 | .Sp |
3482 | .Sp |
2869 | The callback has the type \f(CW\*(C`void (*cb)(int revents, void *arg)\*(C'\fR and gets |
3483 | The callback has the type \f(CW\*(C`void (*cb)(int revents, void *arg)\*(C'\fR and is |
2870 | passed an \f(CW\*(C`revents\*(C'\fR set like normal event callbacks (a combination of |
3484 | passed an \f(CW\*(C`revents\*(C'\fR set like normal event callbacks (a combination of |
2871 | \&\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 |
3485 | \&\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 |
2872 | value passed to \f(CW\*(C`ev_once\*(C'\fR. Note that it is possible to receive \fIboth\fR |
3486 | value passed to \f(CW\*(C`ev_once\*(C'\fR. Note that it is possible to receive \fIboth\fR |
2873 | a timeout and an io event at the same time \- you probably should give io |
3487 | a timeout and an io event at the same time \- you probably should give io |
2874 | events precedence. |
3488 | events precedence. |
2875 | .Sp |
3489 | .Sp |
2876 | Example: wait up to ten seconds for data to appear on \s-1STDIN_FILENO\s0. |
3490 | Example: wait up to ten seconds for data to appear on \s-1STDIN_FILENO\s0. |
… | |
… | |
2878 | .Vb 7 |
3492 | .Vb 7 |
2879 | \& static void stdin_ready (int revents, void *arg) |
3493 | \& static void stdin_ready (int revents, void *arg) |
2880 | \& { |
3494 | \& { |
2881 | \& if (revents & EV_READ) |
3495 | \& if (revents & EV_READ) |
2882 | \& /* stdin might have data for us, joy! */; |
3496 | \& /* stdin might have data for us, joy! */; |
2883 | \& else if (revents & EV_TIMEOUT) |
3497 | \& else if (revents & EV_TIMER) |
2884 | \& /* doh, nothing entered */; |
3498 | \& /* doh, nothing entered */; |
2885 | \& } |
3499 | \& } |
2886 | \& |
3500 | \& |
2887 | \& ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
3501 | \& ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
2888 | .Ve |
3502 | .Ve |
2889 | .IP "ev_feed_event (struct ev_loop *, watcher *, int revents)" 4 |
|
|
2890 | .IX Item "ev_feed_event (struct ev_loop *, watcher *, int revents)" |
|
|
2891 | Feeds the given event set into the event loop, as if the specified event |
|
|
2892 | had happened for the specified watcher (which must be a pointer to an |
|
|
2893 | initialised but not necessarily started event watcher). |
|
|
2894 | .IP "ev_feed_fd_event (struct ev_loop *, int fd, int revents)" 4 |
3503 | .IP "ev_feed_fd_event (loop, int fd, int revents)" 4 |
2895 | .IX Item "ev_feed_fd_event (struct ev_loop *, int fd, int revents)" |
3504 | .IX Item "ev_feed_fd_event (loop, int fd, int revents)" |
2896 | Feed an event on the given fd, as if a file descriptor backend detected |
3505 | Feed an event on the given fd, as if a file descriptor backend detected |
2897 | the given events it. |
3506 | the given events it. |
2898 | .IP "ev_feed_signal_event (struct ev_loop *loop, int signum)" 4 |
3507 | .IP "ev_feed_signal_event (loop, int signum)" 4 |
2899 | .IX Item "ev_feed_signal_event (struct ev_loop *loop, int signum)" |
3508 | .IX Item "ev_feed_signal_event (loop, int signum)" |
2900 | Feed an event as if the given signal occurred (\f(CW\*(C`loop\*(C'\fR must be the default |
3509 | Feed an event as if the given signal occurred. See also \f(CW\*(C`ev_feed_signal\*(C'\fR, |
2901 | loop!). |
3510 | which is async-safe. |
|
|
3511 | .SH "COMMON OR USEFUL IDIOMS (OR BOTH)" |
|
|
3512 | .IX Header "COMMON OR USEFUL IDIOMS (OR BOTH)" |
|
|
3513 | This section explains some common idioms that are not immediately |
|
|
3514 | obvious. Note that examples are sprinkled over the whole manual, and this |
|
|
3515 | section only contains stuff that wouldn't fit anywhere else. |
|
|
3516 | .SS "\s-1ASSOCIATING\s0 \s-1CUSTOM\s0 \s-1DATA\s0 \s-1WITH\s0 A \s-1WATCHER\s0" |
|
|
3517 | .IX Subsection "ASSOCIATING CUSTOM DATA WITH A WATCHER" |
|
|
3518 | Each watcher has, by default, a \f(CW\*(C`void *data\*(C'\fR member that you can read |
|
|
3519 | or modify at any time: libev will completely ignore it. This can be used |
|
|
3520 | to associate arbitrary data with your watcher. If you need more data and |
|
|
3521 | don't want to allocate memory separately and store a pointer to it in that |
|
|
3522 | data member, you can also \*(L"subclass\*(R" the watcher type and provide your own |
|
|
3523 | data: |
|
|
3524 | .PP |
|
|
3525 | .Vb 7 |
|
|
3526 | \& struct my_io |
|
|
3527 | \& { |
|
|
3528 | \& ev_io io; |
|
|
3529 | \& int otherfd; |
|
|
3530 | \& void *somedata; |
|
|
3531 | \& struct whatever *mostinteresting; |
|
|
3532 | \& }; |
|
|
3533 | \& |
|
|
3534 | \& ... |
|
|
3535 | \& struct my_io w; |
|
|
3536 | \& ev_io_init (&w.io, my_cb, fd, EV_READ); |
|
|
3537 | .Ve |
|
|
3538 | .PP |
|
|
3539 | And since your callback will be called with a pointer to the watcher, you |
|
|
3540 | can cast it back to your own type: |
|
|
3541 | .PP |
|
|
3542 | .Vb 5 |
|
|
3543 | \& static void my_cb (struct ev_loop *loop, ev_io *w_, int revents) |
|
|
3544 | \& { |
|
|
3545 | \& struct my_io *w = (struct my_io *)w_; |
|
|
3546 | \& ... |
|
|
3547 | \& } |
|
|
3548 | .Ve |
|
|
3549 | .PP |
|
|
3550 | More interesting and less C\-conformant ways of casting your callback |
|
|
3551 | function type instead have been omitted. |
|
|
3552 | .SS "\s-1BUILDING\s0 \s-1YOUR\s0 \s-1OWN\s0 \s-1COMPOSITE\s0 \s-1WATCHERS\s0" |
|
|
3553 | .IX Subsection "BUILDING YOUR OWN COMPOSITE WATCHERS" |
|
|
3554 | Another common scenario is to use some data structure with multiple |
|
|
3555 | embedded watchers, in effect creating your own watcher that combines |
|
|
3556 | multiple libev event sources into one \*(L"super-watcher\*(R": |
|
|
3557 | .PP |
|
|
3558 | .Vb 6 |
|
|
3559 | \& struct my_biggy |
|
|
3560 | \& { |
|
|
3561 | \& int some_data; |
|
|
3562 | \& ev_timer t1; |
|
|
3563 | \& ev_timer t2; |
|
|
3564 | \& } |
|
|
3565 | .Ve |
|
|
3566 | .PP |
|
|
3567 | In this case getting the pointer to \f(CW\*(C`my_biggy\*(C'\fR is a bit more |
|
|
3568 | complicated: Either you store the address of your \f(CW\*(C`my_biggy\*(C'\fR struct in |
|
|
3569 | the \f(CW\*(C`data\*(C'\fR member of the watcher (for woozies or \*(C+ coders), or you need |
|
|
3570 | to use some pointer arithmetic using \f(CW\*(C`offsetof\*(C'\fR inside your watchers (for |
|
|
3571 | real programmers): |
|
|
3572 | .PP |
|
|
3573 | .Vb 1 |
|
|
3574 | \& #include <stddef.h> |
|
|
3575 | \& |
|
|
3576 | \& static void |
|
|
3577 | \& t1_cb (EV_P_ ev_timer *w, int revents) |
|
|
3578 | \& { |
|
|
3579 | \& struct my_biggy big = (struct my_biggy *) |
|
|
3580 | \& (((char *)w) \- offsetof (struct my_biggy, t1)); |
|
|
3581 | \& } |
|
|
3582 | \& |
|
|
3583 | \& static void |
|
|
3584 | \& t2_cb (EV_P_ ev_timer *w, int revents) |
|
|
3585 | \& { |
|
|
3586 | \& struct my_biggy big = (struct my_biggy *) |
|
|
3587 | \& (((char *)w) \- offsetof (struct my_biggy, t2)); |
|
|
3588 | \& } |
|
|
3589 | .Ve |
|
|
3590 | .SS "\s-1MODEL/NESTED\s0 \s-1EVENT\s0 \s-1LOOP\s0 \s-1INVOCATIONS\s0 \s-1AND\s0 \s-1EXIT\s0 \s-1CONDITIONS\s0" |
|
|
3591 | .IX Subsection "MODEL/NESTED EVENT LOOP INVOCATIONS AND EXIT CONDITIONS" |
|
|
3592 | Often (especially in \s-1GUI\s0 toolkits) there are places where you have |
|
|
3593 | \&\fImodal\fR interaction, which is most easily implemented by recursively |
|
|
3594 | invoking \f(CW\*(C`ev_run\*(C'\fR. |
|
|
3595 | .PP |
|
|
3596 | This brings the problem of exiting \- a callback might want to finish the |
|
|
3597 | main \f(CW\*(C`ev_run\*(C'\fR call, but not the nested one (e.g. user clicked \*(L"Quit\*(R", but |
|
|
3598 | a modal \*(L"Are you sure?\*(R" dialog is still waiting), or just the nested one |
|
|
3599 | and not the main one (e.g. user clocked \*(L"Ok\*(R" in a modal dialog), or some |
|
|
3600 | other combination: In these cases, \f(CW\*(C`ev_break\*(C'\fR will not work alone. |
|
|
3601 | .PP |
|
|
3602 | The solution is to maintain \*(L"break this loop\*(R" variable for each \f(CW\*(C`ev_run\*(C'\fR |
|
|
3603 | invocation, and use a loop around \f(CW\*(C`ev_run\*(C'\fR until the condition is |
|
|
3604 | triggered, using \f(CW\*(C`EVRUN_ONCE\*(C'\fR: |
|
|
3605 | .PP |
|
|
3606 | .Vb 2 |
|
|
3607 | \& // main loop |
|
|
3608 | \& int exit_main_loop = 0; |
|
|
3609 | \& |
|
|
3610 | \& while (!exit_main_loop) |
|
|
3611 | \& ev_run (EV_DEFAULT_ EVRUN_ONCE); |
|
|
3612 | \& |
|
|
3613 | \& // in a model watcher |
|
|
3614 | \& int exit_nested_loop = 0; |
|
|
3615 | \& |
|
|
3616 | \& while (!exit_nested_loop) |
|
|
3617 | \& ev_run (EV_A_ EVRUN_ONCE); |
|
|
3618 | .Ve |
|
|
3619 | .PP |
|
|
3620 | To exit from any of these loops, just set the corresponding exit variable: |
|
|
3621 | .PP |
|
|
3622 | .Vb 2 |
|
|
3623 | \& // exit modal loop |
|
|
3624 | \& exit_nested_loop = 1; |
|
|
3625 | \& |
|
|
3626 | \& // exit main program, after modal loop is finished |
|
|
3627 | \& exit_main_loop = 1; |
|
|
3628 | \& |
|
|
3629 | \& // exit both |
|
|
3630 | \& exit_main_loop = exit_nested_loop = 1; |
|
|
3631 | .Ve |
|
|
3632 | .SS "\s-1THREAD\s0 \s-1LOCKING\s0 \s-1EXAMPLE\s0" |
|
|
3633 | .IX Subsection "THREAD LOCKING EXAMPLE" |
|
|
3634 | Here is a fictitious example of how to run an event loop in a different |
|
|
3635 | thread from where callbacks are being invoked and watchers are |
|
|
3636 | created/added/removed. |
|
|
3637 | .PP |
|
|
3638 | For a real-world example, see the \f(CW\*(C`EV::Loop::Async\*(C'\fR perl module, |
|
|
3639 | which uses exactly this technique (which is suited for many high-level |
|
|
3640 | languages). |
|
|
3641 | .PP |
|
|
3642 | The example uses a pthread mutex to protect the loop data, a condition |
|
|
3643 | variable to wait for callback invocations, an async watcher to notify the |
|
|
3644 | event loop thread and an unspecified mechanism to wake up the main thread. |
|
|
3645 | .PP |
|
|
3646 | First, you need to associate some data with the event loop: |
|
|
3647 | .PP |
|
|
3648 | .Vb 6 |
|
|
3649 | \& typedef struct { |
|
|
3650 | \& mutex_t lock; /* global loop lock */ |
|
|
3651 | \& ev_async async_w; |
|
|
3652 | \& thread_t tid; |
|
|
3653 | \& cond_t invoke_cv; |
|
|
3654 | \& } userdata; |
|
|
3655 | \& |
|
|
3656 | \& void prepare_loop (EV_P) |
|
|
3657 | \& { |
|
|
3658 | \& // for simplicity, we use a static userdata struct. |
|
|
3659 | \& static userdata u; |
|
|
3660 | \& |
|
|
3661 | \& ev_async_init (&u\->async_w, async_cb); |
|
|
3662 | \& ev_async_start (EV_A_ &u\->async_w); |
|
|
3663 | \& |
|
|
3664 | \& pthread_mutex_init (&u\->lock, 0); |
|
|
3665 | \& pthread_cond_init (&u\->invoke_cv, 0); |
|
|
3666 | \& |
|
|
3667 | \& // now associate this with the loop |
|
|
3668 | \& ev_set_userdata (EV_A_ u); |
|
|
3669 | \& ev_set_invoke_pending_cb (EV_A_ l_invoke); |
|
|
3670 | \& ev_set_loop_release_cb (EV_A_ l_release, l_acquire); |
|
|
3671 | \& |
|
|
3672 | \& // then create the thread running ev_run |
|
|
3673 | \& pthread_create (&u\->tid, 0, l_run, EV_A); |
|
|
3674 | \& } |
|
|
3675 | .Ve |
|
|
3676 | .PP |
|
|
3677 | The callback for the \f(CW\*(C`ev_async\*(C'\fR watcher does nothing: the watcher is used |
|
|
3678 | solely to wake up the event loop so it takes notice of any new watchers |
|
|
3679 | that might have been added: |
|
|
3680 | .PP |
|
|
3681 | .Vb 5 |
|
|
3682 | \& static void |
|
|
3683 | \& async_cb (EV_P_ ev_async *w, int revents) |
|
|
3684 | \& { |
|
|
3685 | \& // just used for the side effects |
|
|
3686 | \& } |
|
|
3687 | .Ve |
|
|
3688 | .PP |
|
|
3689 | The \f(CW\*(C`l_release\*(C'\fR and \f(CW\*(C`l_acquire\*(C'\fR callbacks simply unlock/lock the mutex |
|
|
3690 | protecting the loop data, respectively. |
|
|
3691 | .PP |
|
|
3692 | .Vb 6 |
|
|
3693 | \& static void |
|
|
3694 | \& l_release (EV_P) |
|
|
3695 | \& { |
|
|
3696 | \& userdata *u = ev_userdata (EV_A); |
|
|
3697 | \& pthread_mutex_unlock (&u\->lock); |
|
|
3698 | \& } |
|
|
3699 | \& |
|
|
3700 | \& static void |
|
|
3701 | \& l_acquire (EV_P) |
|
|
3702 | \& { |
|
|
3703 | \& userdata *u = ev_userdata (EV_A); |
|
|
3704 | \& pthread_mutex_lock (&u\->lock); |
|
|
3705 | \& } |
|
|
3706 | .Ve |
|
|
3707 | .PP |
|
|
3708 | The event loop thread first acquires the mutex, and then jumps straight |
|
|
3709 | into \f(CW\*(C`ev_run\*(C'\fR: |
|
|
3710 | .PP |
|
|
3711 | .Vb 4 |
|
|
3712 | \& void * |
|
|
3713 | \& l_run (void *thr_arg) |
|
|
3714 | \& { |
|
|
3715 | \& struct ev_loop *loop = (struct ev_loop *)thr_arg; |
|
|
3716 | \& |
|
|
3717 | \& l_acquire (EV_A); |
|
|
3718 | \& pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0); |
|
|
3719 | \& ev_run (EV_A_ 0); |
|
|
3720 | \& l_release (EV_A); |
|
|
3721 | \& |
|
|
3722 | \& return 0; |
|
|
3723 | \& } |
|
|
3724 | .Ve |
|
|
3725 | .PP |
|
|
3726 | Instead of invoking all pending watchers, the \f(CW\*(C`l_invoke\*(C'\fR callback will |
|
|
3727 | signal the main thread via some unspecified mechanism (signals? pipe |
|
|
3728 | writes? \f(CW\*(C`Async::Interrupt\*(C'\fR?) and then waits until all pending watchers |
|
|
3729 | have been called (in a while loop because a) spurious wakeups are possible |
|
|
3730 | and b) skipping inter-thread-communication when there are no pending |
|
|
3731 | watchers is very beneficial): |
|
|
3732 | .PP |
|
|
3733 | .Vb 4 |
|
|
3734 | \& static void |
|
|
3735 | \& l_invoke (EV_P) |
|
|
3736 | \& { |
|
|
3737 | \& userdata *u = ev_userdata (EV_A); |
|
|
3738 | \& |
|
|
3739 | \& while (ev_pending_count (EV_A)) |
|
|
3740 | \& { |
|
|
3741 | \& wake_up_other_thread_in_some_magic_or_not_so_magic_way (); |
|
|
3742 | \& pthread_cond_wait (&u\->invoke_cv, &u\->lock); |
|
|
3743 | \& } |
|
|
3744 | \& } |
|
|
3745 | .Ve |
|
|
3746 | .PP |
|
|
3747 | Now, whenever the main thread gets told to invoke pending watchers, it |
|
|
3748 | will grab the lock, call \f(CW\*(C`ev_invoke_pending\*(C'\fR and then signal the loop |
|
|
3749 | thread to continue: |
|
|
3750 | .PP |
|
|
3751 | .Vb 4 |
|
|
3752 | \& static void |
|
|
3753 | \& real_invoke_pending (EV_P) |
|
|
3754 | \& { |
|
|
3755 | \& userdata *u = ev_userdata (EV_A); |
|
|
3756 | \& |
|
|
3757 | \& pthread_mutex_lock (&u\->lock); |
|
|
3758 | \& ev_invoke_pending (EV_A); |
|
|
3759 | \& pthread_cond_signal (&u\->invoke_cv); |
|
|
3760 | \& pthread_mutex_unlock (&u\->lock); |
|
|
3761 | \& } |
|
|
3762 | .Ve |
|
|
3763 | .PP |
|
|
3764 | Whenever you want to start/stop a watcher or do other modifications to an |
|
|
3765 | event loop, you will now have to lock: |
|
|
3766 | .PP |
|
|
3767 | .Vb 2 |
|
|
3768 | \& ev_timer timeout_watcher; |
|
|
3769 | \& userdata *u = ev_userdata (EV_A); |
|
|
3770 | \& |
|
|
3771 | \& ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.); |
|
|
3772 | \& |
|
|
3773 | \& pthread_mutex_lock (&u\->lock); |
|
|
3774 | \& ev_timer_start (EV_A_ &timeout_watcher); |
|
|
3775 | \& ev_async_send (EV_A_ &u\->async_w); |
|
|
3776 | \& pthread_mutex_unlock (&u\->lock); |
|
|
3777 | .Ve |
|
|
3778 | .PP |
|
|
3779 | Note that sending the \f(CW\*(C`ev_async\*(C'\fR watcher is required because otherwise |
|
|
3780 | an event loop currently blocking in the kernel will have no knowledge |
|
|
3781 | about the newly added timer. By waking up the loop it will pick up any new |
|
|
3782 | watchers in the next event loop iteration. |
|
|
3783 | .SS "\s-1THREADS\s0, \s-1COROUTINES\s0, \s-1CONTINUATIONS\s0, \s-1QUEUES\s0... \s-1INSTEAD\s0 \s-1OF\s0 \s-1CALLBACKS\s0" |
|
|
3784 | .IX Subsection "THREADS, COROUTINES, CONTINUATIONS, QUEUES... INSTEAD OF CALLBACKS" |
|
|
3785 | While the overhead of a callback that e.g. schedules a thread is small, it |
|
|
3786 | is still an overhead. If you embed libev, and your main usage is with some |
|
|
3787 | kind of threads or coroutines, you might want to customise libev so that |
|
|
3788 | doesn't need callbacks anymore. |
|
|
3789 | .PP |
|
|
3790 | Imagine you have coroutines that you can switch to using a function |
|
|
3791 | \&\f(CW\*(C`switch_to (coro)\*(C'\fR, that libev runs in a coroutine called \f(CW\*(C`libev_coro\*(C'\fR |
|
|
3792 | and that due to some magic, the currently active coroutine is stored in a |
|
|
3793 | global called \f(CW\*(C`current_coro\*(C'\fR. Then you can build your own \*(L"wait for libev |
|
|
3794 | event\*(R" primitive by changing \f(CW\*(C`EV_CB_DECLARE\*(C'\fR and \f(CW\*(C`EV_CB_INVOKE\*(C'\fR (note |
|
|
3795 | the differing \f(CW\*(C`;\*(C'\fR conventions): |
|
|
3796 | .PP |
|
|
3797 | .Vb 2 |
|
|
3798 | \& #define EV_CB_DECLARE(type) struct my_coro *cb; |
|
|
3799 | \& #define EV_CB_INVOKE(watcher) switch_to ((watcher)\->cb) |
|
|
3800 | .Ve |
|
|
3801 | .PP |
|
|
3802 | That means instead of having a C callback function, you store the |
|
|
3803 | coroutine to switch to in each watcher, and instead of having libev call |
|
|
3804 | your callback, you instead have it switch to that coroutine. |
|
|
3805 | .PP |
|
|
3806 | A coroutine might now wait for an event with a function called |
|
|
3807 | \&\f(CW\*(C`wait_for_event\*(C'\fR. (the watcher needs to be started, as always, but it doesn't |
|
|
3808 | matter when, or whether the watcher is active or not when this function is |
|
|
3809 | called): |
|
|
3810 | .PP |
|
|
3811 | .Vb 6 |
|
|
3812 | \& void |
|
|
3813 | \& wait_for_event (ev_watcher *w) |
|
|
3814 | \& { |
|
|
3815 | \& ev_cb_set (w) = current_coro; |
|
|
3816 | \& switch_to (libev_coro); |
|
|
3817 | \& } |
|
|
3818 | .Ve |
|
|
3819 | .PP |
|
|
3820 | That basically suspends the coroutine inside \f(CW\*(C`wait_for_event\*(C'\fR and |
|
|
3821 | continues the libev coroutine, which, when appropriate, switches back to |
|
|
3822 | this or any other coroutine. I am sure if you sue this your own :) |
|
|
3823 | .PP |
|
|
3824 | You can do similar tricks if you have, say, threads with an event queue \- |
|
|
3825 | instead of storing a coroutine, you store the queue object and instead of |
|
|
3826 | switching to a coroutine, you push the watcher onto the queue and notify |
|
|
3827 | any waiters. |
|
|
3828 | .PP |
|
|
3829 | To embed libev, see \s-1EMBEDDING\s0, but in short, it's easiest to create two |
|
|
3830 | files, \fImy_ev.h\fR and \fImy_ev.c\fR that include the respective libev files: |
|
|
3831 | .PP |
|
|
3832 | .Vb 4 |
|
|
3833 | \& // my_ev.h |
|
|
3834 | \& #define EV_CB_DECLARE(type) struct my_coro *cb; |
|
|
3835 | \& #define EV_CB_INVOKE(watcher) switch_to ((watcher)\->cb); |
|
|
3836 | \& #include "../libev/ev.h" |
|
|
3837 | \& |
|
|
3838 | \& // my_ev.c |
|
|
3839 | \& #define EV_H "my_ev.h" |
|
|
3840 | \& #include "../libev/ev.c" |
|
|
3841 | .Ve |
|
|
3842 | .PP |
|
|
3843 | And then use \fImy_ev.h\fR when you would normally use \fIev.h\fR, and compile |
|
|
3844 | \&\fImy_ev.c\fR into your project. When properly specifying include paths, you |
|
|
3845 | can even use \fIev.h\fR as header file name directly. |
2902 | .SH "LIBEVENT EMULATION" |
3846 | .SH "LIBEVENT EMULATION" |
2903 | .IX Header "LIBEVENT EMULATION" |
3847 | .IX Header "LIBEVENT EMULATION" |
2904 | Libev offers a compatibility emulation layer for libevent. It cannot |
3848 | Libev offers a compatibility emulation layer for libevent. It cannot |
2905 | emulate the internals of libevent, so here are some usage hints: |
3849 | emulate the internals of libevent, so here are some usage hints: |
|
|
3850 | .IP "\(bu" 4 |
|
|
3851 | Only the libevent\-1.4.1\-beta \s-1API\s0 is being emulated. |
|
|
3852 | .Sp |
|
|
3853 | This was the newest libevent version available when libev was implemented, |
|
|
3854 | and is still mostly unchanged in 2010. |
2906 | .IP "\(bu" 4 |
3855 | .IP "\(bu" 4 |
2907 | Use it by including <event.h>, as usual. |
3856 | Use it by including <event.h>, as usual. |
2908 | .IP "\(bu" 4 |
3857 | .IP "\(bu" 4 |
2909 | The following members are fully supported: ev_base, ev_callback, |
3858 | The following members are fully supported: ev_base, ev_callback, |
2910 | ev_arg, ev_fd, ev_res, ev_events. |
3859 | ev_arg, ev_fd, ev_res, ev_events. |
… | |
… | |
2916 | Priorities are not currently supported. Initialising priorities |
3865 | Priorities are not currently supported. Initialising priorities |
2917 | will fail and all watchers will have the same priority, even though there |
3866 | will fail and all watchers will have the same priority, even though there |
2918 | is an ev_pri field. |
3867 | is an ev_pri field. |
2919 | .IP "\(bu" 4 |
3868 | .IP "\(bu" 4 |
2920 | In libevent, the last base created gets the signals, in libev, the |
3869 | In libevent, the last base created gets the signals, in libev, the |
2921 | first base created (== the default loop) gets the signals. |
3870 | base that registered the signal gets the signals. |
2922 | .IP "\(bu" 4 |
3871 | .IP "\(bu" 4 |
2923 | Other members are not supported. |
3872 | Other members are not supported. |
2924 | .IP "\(bu" 4 |
3873 | .IP "\(bu" 4 |
2925 | The libev emulation is \fInot\fR \s-1ABI\s0 compatible to libevent, you need |
3874 | The libev emulation is \fInot\fR \s-1ABI\s0 compatible to libevent, you need |
2926 | to use the libev header file and library. |
3875 | to use the libev header file and library. |
… | |
… | |
2944 | Care has been taken to keep the overhead low. The only data member the \*(C+ |
3893 | Care has been taken to keep the overhead low. The only data member the \*(C+ |
2945 | classes add (compared to plain C\-style watchers) is the event loop pointer |
3894 | classes add (compared to plain C\-style watchers) is the event loop pointer |
2946 | that the watcher is associated with (or no additional members at all if |
3895 | that the watcher is associated with (or no additional members at all if |
2947 | you disable \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR when embedding libev). |
3896 | you disable \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR when embedding libev). |
2948 | .PP |
3897 | .PP |
2949 | Currently, functions, and static and non-static member functions can be |
3898 | Currently, functions, static and non-static member functions and classes |
2950 | used as callbacks. Other types should be easy to add as long as they only |
3899 | with \f(CW\*(C`operator ()\*(C'\fR can be used as callbacks. Other types should be easy |
2951 | need one additional pointer for context. If you need support for other |
3900 | to add as long as they only need one additional pointer for context. If |
2952 | types of functors please contact the author (preferably after implementing |
3901 | you need support for other types of functors please contact the author |
2953 | it). |
3902 | (preferably after implementing it). |
2954 | .PP |
3903 | .PP |
2955 | Here is a list of things available in the \f(CW\*(C`ev\*(C'\fR namespace: |
3904 | Here is a list of things available in the \f(CW\*(C`ev\*(C'\fR namespace: |
2956 | .ie n .IP """ev::READ""\fR, \f(CW""ev::WRITE"" etc." 4 |
3905 | .ie n .IP """ev::READ"", ""ev::WRITE"" etc." 4 |
2957 | .el .IP "\f(CWev::READ\fR, \f(CWev::WRITE\fR etc." 4 |
3906 | .el .IP "\f(CWev::READ\fR, \f(CWev::WRITE\fR etc." 4 |
2958 | .IX Item "ev::READ, ev::WRITE etc." |
3907 | .IX Item "ev::READ, ev::WRITE etc." |
2959 | These are just enum values with the same values as the \f(CW\*(C`EV_READ\*(C'\fR etc. |
3908 | These are just enum values with the same values as the \f(CW\*(C`EV_READ\*(C'\fR etc. |
2960 | macros from \fIev.h\fR. |
3909 | macros from \fIev.h\fR. |
2961 | .ie n .IP """ev::tstamp""\fR, \f(CW""ev::now""" 4 |
3910 | .ie n .IP """ev::tstamp"", ""ev::now""" 4 |
2962 | .el .IP "\f(CWev::tstamp\fR, \f(CWev::now\fR" 4 |
3911 | .el .IP "\f(CWev::tstamp\fR, \f(CWev::now\fR" 4 |
2963 | .IX Item "ev::tstamp, ev::now" |
3912 | .IX Item "ev::tstamp, ev::now" |
2964 | Aliases to the same types/functions as with the \f(CW\*(C`ev_\*(C'\fR prefix. |
3913 | Aliases to the same types/functions as with the \f(CW\*(C`ev_\*(C'\fR prefix. |
2965 | .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 |
3914 | .ie n .IP """ev::io"", ""ev::timer"", ""ev::periodic"", ""ev::idle"", ""ev::sig"" etc." 4 |
2966 | .el .IP "\f(CWev::io\fR, \f(CWev::timer\fR, \f(CWev::periodic\fR, \f(CWev::idle\fR, \f(CWev::sig\fR etc." 4 |
3915 | .el .IP "\f(CWev::io\fR, \f(CWev::timer\fR, \f(CWev::periodic\fR, \f(CWev::idle\fR, \f(CWev::sig\fR etc." 4 |
2967 | .IX Item "ev::io, ev::timer, ev::periodic, ev::idle, ev::sig etc." |
3916 | .IX Item "ev::io, ev::timer, ev::periodic, ev::idle, ev::sig etc." |
2968 | For each \f(CW\*(C`ev_TYPE\*(C'\fR watcher in \fIev.h\fR there is a corresponding class of |
3917 | For each \f(CW\*(C`ev_TYPE\*(C'\fR watcher in \fIev.h\fR there is a corresponding class of |
2969 | the same name in the \f(CW\*(C`ev\*(C'\fR namespace, with the exception of \f(CW\*(C`ev_signal\*(C'\fR |
3918 | the same name in the \f(CW\*(C`ev\*(C'\fR namespace, with the exception of \f(CW\*(C`ev_signal\*(C'\fR |
2970 | which is called \f(CW\*(C`ev::sig\*(C'\fR to avoid clashes with the \f(CW\*(C`signal\*(C'\fR macro |
3919 | which is called \f(CW\*(C`ev::sig\*(C'\fR to avoid clashes with the \f(CW\*(C`signal\*(C'\fR macro |
… | |
… | |
2973 | All of those classes have these methods: |
3922 | All of those classes have these methods: |
2974 | .RS 4 |
3923 | .RS 4 |
2975 | .IP "ev::TYPE::TYPE ()" 4 |
3924 | .IP "ev::TYPE::TYPE ()" 4 |
2976 | .IX Item "ev::TYPE::TYPE ()" |
3925 | .IX Item "ev::TYPE::TYPE ()" |
2977 | .PD 0 |
3926 | .PD 0 |
2978 | .IP "ev::TYPE::TYPE (struct ev_loop *)" 4 |
3927 | .IP "ev::TYPE::TYPE (loop)" 4 |
2979 | .IX Item "ev::TYPE::TYPE (struct ev_loop *)" |
3928 | .IX Item "ev::TYPE::TYPE (loop)" |
2980 | .IP "ev::TYPE::~TYPE" 4 |
3929 | .IP "ev::TYPE::~TYPE" 4 |
2981 | .IX Item "ev::TYPE::~TYPE" |
3930 | .IX Item "ev::TYPE::~TYPE" |
2982 | .PD |
3931 | .PD |
2983 | The constructor (optionally) takes an event loop to associate the watcher |
3932 | The constructor (optionally) takes an event loop to associate the watcher |
2984 | with. If it is omitted, it will use \f(CW\*(C`EV_DEFAULT\*(C'\fR. |
3933 | with. If it is omitted, it will use \f(CW\*(C`EV_DEFAULT\*(C'\fR. |
… | |
… | |
3016 | \& |
3965 | \& |
3017 | \& myclass obj; |
3966 | \& myclass obj; |
3018 | \& ev::io iow; |
3967 | \& ev::io iow; |
3019 | \& iow.set <myclass, &myclass::io_cb> (&obj); |
3968 | \& iow.set <myclass, &myclass::io_cb> (&obj); |
3020 | .Ve |
3969 | .Ve |
|
|
3970 | .IP "w\->set (object *)" 4 |
|
|
3971 | .IX Item "w->set (object *)" |
|
|
3972 | This is a variation of a method callback \- leaving out the method to call |
|
|
3973 | will default the method to \f(CW\*(C`operator ()\*(C'\fR, which makes it possible to use |
|
|
3974 | functor objects without having to manually specify the \f(CW\*(C`operator ()\*(C'\fR all |
|
|
3975 | the time. Incidentally, you can then also leave out the template argument |
|
|
3976 | list. |
|
|
3977 | .Sp |
|
|
3978 | The \f(CW\*(C`operator ()\*(C'\fR method prototype must be \f(CW\*(C`void operator ()(watcher &w, |
|
|
3979 | int revents)\*(C'\fR. |
|
|
3980 | .Sp |
|
|
3981 | See the method\-\f(CW\*(C`set\*(C'\fR above for more details. |
|
|
3982 | .Sp |
|
|
3983 | Example: use a functor object as callback. |
|
|
3984 | .Sp |
|
|
3985 | .Vb 7 |
|
|
3986 | \& struct myfunctor |
|
|
3987 | \& { |
|
|
3988 | \& void operator() (ev::io &w, int revents) |
|
|
3989 | \& { |
|
|
3990 | \& ... |
|
|
3991 | \& } |
|
|
3992 | \& } |
|
|
3993 | \& |
|
|
3994 | \& myfunctor f; |
|
|
3995 | \& |
|
|
3996 | \& ev::io w; |
|
|
3997 | \& w.set (&f); |
|
|
3998 | .Ve |
3021 | .IP "w\->set<function> (void *data = 0)" 4 |
3999 | .IP "w\->set<function> (void *data = 0)" 4 |
3022 | .IX Item "w->set<function> (void *data = 0)" |
4000 | .IX Item "w->set<function> (void *data = 0)" |
3023 | Also sets a callback, but uses a static method or plain function as |
4001 | Also sets a callback, but uses a static method or plain function as |
3024 | callback. The optional \f(CW\*(C`data\*(C'\fR argument will be stored in the watcher's |
4002 | callback. The optional \f(CW\*(C`data\*(C'\fR argument will be stored in the watcher's |
3025 | \&\f(CW\*(C`data\*(C'\fR member and is free for you to use. |
4003 | \&\f(CW\*(C`data\*(C'\fR member and is free for you to use. |
… | |
… | |
3032 | .Sp |
4010 | .Sp |
3033 | .Vb 2 |
4011 | .Vb 2 |
3034 | \& static void io_cb (ev::io &w, int revents) { } |
4012 | \& static void io_cb (ev::io &w, int revents) { } |
3035 | \& iow.set <io_cb> (); |
4013 | \& iow.set <io_cb> (); |
3036 | .Ve |
4014 | .Ve |
3037 | .IP "w\->set (struct ev_loop *)" 4 |
4015 | .IP "w\->set (loop)" 4 |
3038 | .IX Item "w->set (struct ev_loop *)" |
4016 | .IX Item "w->set (loop)" |
3039 | Associates a different \f(CW\*(C`struct ev_loop\*(C'\fR with this watcher. You can only |
4017 | Associates a different \f(CW\*(C`struct ev_loop\*(C'\fR with this watcher. You can only |
3040 | do this when the watcher is inactive (and not pending either). |
4018 | do this when the watcher is inactive (and not pending either). |
3041 | .IP "w\->set ([arguments])" 4 |
4019 | .IP "w\->set ([arguments])" 4 |
3042 | .IX Item "w->set ([arguments])" |
4020 | .IX Item "w->set ([arguments])" |
3043 | Basically the same as \f(CW\*(C`ev_TYPE_set\*(C'\fR, with the same arguments. Must be |
4021 | Basically the same as \f(CW\*(C`ev_TYPE_set\*(C'\fR, with the same arguments. Either this |
3044 | called at least once. Unlike the C counterpart, an active watcher gets |
4022 | method or a suitable start method must be called at least once. Unlike the |
3045 | automatically stopped and restarted when reconfiguring it with this |
4023 | C counterpart, an active watcher gets automatically stopped and restarted |
3046 | method. |
4024 | when reconfiguring it with this method. |
3047 | .IP "w\->start ()" 4 |
4025 | .IP "w\->start ()" 4 |
3048 | .IX Item "w->start ()" |
4026 | .IX Item "w->start ()" |
3049 | Starts the watcher. Note that there is no \f(CW\*(C`loop\*(C'\fR argument, as the |
4027 | Starts the watcher. Note that there is no \f(CW\*(C`loop\*(C'\fR argument, as the |
3050 | constructor already stores the event loop. |
4028 | constructor already stores the event loop. |
|
|
4029 | .IP "w\->start ([arguments])" 4 |
|
|
4030 | .IX Item "w->start ([arguments])" |
|
|
4031 | Instead of calling \f(CW\*(C`set\*(C'\fR and \f(CW\*(C`start\*(C'\fR methods separately, it is often |
|
|
4032 | convenient to wrap them in one call. Uses the same type of arguments as |
|
|
4033 | the configure \f(CW\*(C`set\*(C'\fR method of the watcher. |
3051 | .IP "w\->stop ()" 4 |
4034 | .IP "w\->stop ()" 4 |
3052 | .IX Item "w->stop ()" |
4035 | .IX Item "w->stop ()" |
3053 | Stops the watcher if it is active. Again, no \f(CW\*(C`loop\*(C'\fR argument. |
4036 | Stops the watcher if it is active. Again, no \f(CW\*(C`loop\*(C'\fR argument. |
3054 | .ie n .IP "w\->again () (""ev::timer""\fR, \f(CW""ev::periodic"" only)" 4 |
4037 | .ie n .IP "w\->again () (""ev::timer"", ""ev::periodic"" only)" 4 |
3055 | .el .IP "w\->again () (\f(CWev::timer\fR, \f(CWev::periodic\fR only)" 4 |
4038 | .el .IP "w\->again () (\f(CWev::timer\fR, \f(CWev::periodic\fR only)" 4 |
3056 | .IX Item "w->again () (ev::timer, ev::periodic only)" |
4039 | .IX Item "w->again () (ev::timer, ev::periodic only)" |
3057 | For \f(CW\*(C`ev::timer\*(C'\fR and \f(CW\*(C`ev::periodic\*(C'\fR, this invokes the corresponding |
4040 | For \f(CW\*(C`ev::timer\*(C'\fR and \f(CW\*(C`ev::periodic\*(C'\fR, this invokes the corresponding |
3058 | \&\f(CW\*(C`ev_TYPE_again\*(C'\fR function. |
4041 | \&\f(CW\*(C`ev_TYPE_again\*(C'\fR function. |
3059 | .ie n .IP "w\->sweep () (""ev::embed"" only)" 4 |
4042 | .ie n .IP "w\->sweep () (""ev::embed"" only)" 4 |
… | |
… | |
3066 | Invokes \f(CW\*(C`ev_stat_stat\*(C'\fR. |
4049 | Invokes \f(CW\*(C`ev_stat_stat\*(C'\fR. |
3067 | .RE |
4050 | .RE |
3068 | .RS 4 |
4051 | .RS 4 |
3069 | .RE |
4052 | .RE |
3070 | .PP |
4053 | .PP |
3071 | Example: Define a class with an \s-1IO\s0 and idle watcher, start one of them in |
4054 | Example: Define a class with two I/O and idle watchers, start the I/O |
3072 | the constructor. |
4055 | watchers in the constructor. |
3073 | .PP |
4056 | .PP |
3074 | .Vb 4 |
4057 | .Vb 5 |
3075 | \& class myclass |
4058 | \& class myclass |
3076 | \& { |
4059 | \& { |
3077 | \& ev::io io ; void io_cb (ev::io &w, int revents); |
4060 | \& ev::io io ; void io_cb (ev::io &w, int revents); |
|
|
4061 | \& ev::io2 io2 ; void io2_cb (ev::io &w, int revents); |
3078 | \& ev::idle idle; void idle_cb (ev::idle &w, int revents); |
4062 | \& ev::idle idle; void idle_cb (ev::idle &w, int revents); |
3079 | \& |
4063 | \& |
3080 | \& myclass (int fd) |
4064 | \& myclass (int fd) |
3081 | \& { |
4065 | \& { |
3082 | \& io .set <myclass, &myclass::io_cb > (this); |
4066 | \& io .set <myclass, &myclass::io_cb > (this); |
|
|
4067 | \& io2 .set <myclass, &myclass::io2_cb > (this); |
3083 | \& idle.set <myclass, &myclass::idle_cb> (this); |
4068 | \& idle.set <myclass, &myclass::idle_cb> (this); |
3084 | \& |
4069 | \& |
3085 | \& io.start (fd, ev::READ); |
4070 | \& io.set (fd, ev::WRITE); // configure the watcher |
|
|
4071 | \& io.start (); // start it whenever convenient |
|
|
4072 | \& |
|
|
4073 | \& io2.start (fd, ev::READ); // set + start in one call |
3086 | \& } |
4074 | \& } |
3087 | \& }; |
4075 | \& }; |
3088 | .Ve |
4076 | .Ve |
3089 | .SH "OTHER LANGUAGE BINDINGS" |
4077 | .SH "OTHER LANGUAGE BINDINGS" |
3090 | .IX Header "OTHER LANGUAGE BINDINGS" |
4078 | .IX Header "OTHER LANGUAGE BINDINGS" |
… | |
… | |
3104 | It can be found and installed via \s-1CPAN\s0, its homepage is at |
4092 | It can be found and installed via \s-1CPAN\s0, its homepage is at |
3105 | <http://software.schmorp.de/pkg/EV>. |
4093 | <http://software.schmorp.de/pkg/EV>. |
3106 | .IP "Python" 4 |
4094 | .IP "Python" 4 |
3107 | .IX Item "Python" |
4095 | .IX Item "Python" |
3108 | Python bindings can be found at <http://code.google.com/p/pyev/>. It |
4096 | Python bindings can be found at <http://code.google.com/p/pyev/>. It |
3109 | seems to be quite complete and well-documented. Note, however, that the |
4097 | seems to be quite complete and well-documented. |
3110 | patch they require for libev is outright dangerous as it breaks the \s-1ABI\s0 |
|
|
3111 | for everybody else, and therefore, should never be applied in an installed |
|
|
3112 | libev (if python requires an incompatible \s-1ABI\s0 then it needs to embed |
|
|
3113 | libev). |
|
|
3114 | .IP "Ruby" 4 |
4098 | .IP "Ruby" 4 |
3115 | .IX Item "Ruby" |
4099 | .IX Item "Ruby" |
3116 | Tony Arcieri has written a ruby extension that offers access to a subset |
4100 | Tony Arcieri has written a ruby extension that offers access to a subset |
3117 | of the libev \s-1API\s0 and adds file handle abstractions, asynchronous \s-1DNS\s0 and |
4101 | of the libev \s-1API\s0 and adds file handle abstractions, asynchronous \s-1DNS\s0 and |
3118 | more on top of it. It can be found via gem servers. Its homepage is at |
4102 | more on top of it. It can be found via gem servers. Its homepage is at |
3119 | <http://rev.rubyforge.org/>. |
4103 | <http://rev.rubyforge.org/>. |
|
|
4104 | .Sp |
|
|
4105 | Roger Pack reports that using the link order \f(CW\*(C`\-lws2_32 \-lmsvcrt\-ruby\-190\*(C'\fR |
|
|
4106 | makes rev work even on mingw. |
|
|
4107 | .IP "Haskell" 4 |
|
|
4108 | .IX Item "Haskell" |
|
|
4109 | A haskell binding to libev is available at |
|
|
4110 | <http://hackage.haskell.org/cgi\-bin/hackage\-scripts/package/hlibev>. |
3120 | .IP "D" 4 |
4111 | .IP "D" 4 |
3121 | .IX Item "D" |
4112 | .IX Item "D" |
3122 | Leandro Lucarella has written a D language binding (\fIev.d\fR) for libev, to |
4113 | Leandro Lucarella has written a D language binding (\fIev.d\fR) for libev, to |
3123 | be found at <http://proj.llucax.com.ar/wiki/evd>. |
4114 | be found at <http://proj.llucax.com.ar/wiki/evd>. |
3124 | .IP "Ocaml" 4 |
4115 | .IP "Ocaml" 4 |
3125 | .IX Item "Ocaml" |
4116 | .IX Item "Ocaml" |
3126 | Erkki Seppala has written Ocaml bindings for libev, to be found at |
4117 | Erkki Seppala has written Ocaml bindings for libev, to be found at |
3127 | <http://modeemi.cs.tut.fi/~flux/software/ocaml\-ev/>. |
4118 | <http://modeemi.cs.tut.fi/~flux/software/ocaml\-ev/>. |
|
|
4119 | .IP "Lua" 4 |
|
|
4120 | .IX Item "Lua" |
|
|
4121 | Brian Maher has written a partial interface to libev for lua (at the |
|
|
4122 | time of this writing, only \f(CW\*(C`ev_io\*(C'\fR and \f(CW\*(C`ev_timer\*(C'\fR), to be found at |
|
|
4123 | <http://github.com/brimworks/lua\-ev>. |
3128 | .SH "MACRO MAGIC" |
4124 | .SH "MACRO MAGIC" |
3129 | .IX Header "MACRO MAGIC" |
4125 | .IX Header "MACRO MAGIC" |
3130 | Libev can be compiled with a variety of options, the most fundamental |
4126 | Libev can be compiled with a variety of options, the most fundamental |
3131 | of which is \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. This option determines whether (most) |
4127 | of which is \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. This option determines whether (most) |
3132 | functions and callbacks have an initial \f(CW\*(C`struct ev_loop *\*(C'\fR argument. |
4128 | functions and callbacks have an initial \f(CW\*(C`struct ev_loop *\*(C'\fR argument. |
3133 | .PP |
4129 | .PP |
3134 | To make it easier to write programs that cope with either variant, the |
4130 | To make it easier to write programs that cope with either variant, the |
3135 | following macros are defined: |
4131 | following macros are defined: |
3136 | .ie n .IP """EV_A""\fR, \f(CW""EV_A_""" 4 |
4132 | .ie n .IP """EV_A"", ""EV_A_""" 4 |
3137 | .el .IP "\f(CWEV_A\fR, \f(CWEV_A_\fR" 4 |
4133 | .el .IP "\f(CWEV_A\fR, \f(CWEV_A_\fR" 4 |
3138 | .IX Item "EV_A, EV_A_" |
4134 | .IX Item "EV_A, EV_A_" |
3139 | This provides the loop \fIargument\fR for functions, if one is required (\*(L"ev |
4135 | This provides the loop \fIargument\fR for functions, if one is required (\*(L"ev |
3140 | loop argument\*(R"). The \f(CW\*(C`EV_A\*(C'\fR form is used when this is the sole argument, |
4136 | loop argument\*(R"). The \f(CW\*(C`EV_A\*(C'\fR form is used when this is the sole argument, |
3141 | \&\f(CW\*(C`EV_A_\*(C'\fR is used when other arguments are following. Example: |
4137 | \&\f(CW\*(C`EV_A_\*(C'\fR is used when other arguments are following. Example: |
3142 | .Sp |
4138 | .Sp |
3143 | .Vb 3 |
4139 | .Vb 3 |
3144 | \& ev_unref (EV_A); |
4140 | \& ev_unref (EV_A); |
3145 | \& ev_timer_add (EV_A_ watcher); |
4141 | \& ev_timer_add (EV_A_ watcher); |
3146 | \& ev_loop (EV_A_ 0); |
4142 | \& ev_run (EV_A_ 0); |
3147 | .Ve |
4143 | .Ve |
3148 | .Sp |
4144 | .Sp |
3149 | It assumes the variable \f(CW\*(C`loop\*(C'\fR of type \f(CW\*(C`struct ev_loop *\*(C'\fR is in scope, |
4145 | It assumes the variable \f(CW\*(C`loop\*(C'\fR of type \f(CW\*(C`struct ev_loop *\*(C'\fR is in scope, |
3150 | which is often provided by the following macro. |
4146 | which is often provided by the following macro. |
3151 | .ie n .IP """EV_P""\fR, \f(CW""EV_P_""" 4 |
4147 | .ie n .IP """EV_P"", ""EV_P_""" 4 |
3152 | .el .IP "\f(CWEV_P\fR, \f(CWEV_P_\fR" 4 |
4148 | .el .IP "\f(CWEV_P\fR, \f(CWEV_P_\fR" 4 |
3153 | .IX Item "EV_P, EV_P_" |
4149 | .IX Item "EV_P, EV_P_" |
3154 | This provides the loop \fIparameter\fR for functions, if one is required (\*(L"ev |
4150 | This provides the loop \fIparameter\fR for functions, if one is required (\*(L"ev |
3155 | loop parameter\*(R"). The \f(CW\*(C`EV_P\*(C'\fR form is used when this is the sole parameter, |
4151 | loop parameter\*(R"). The \f(CW\*(C`EV_P\*(C'\fR form is used when this is the sole parameter, |
3156 | \&\f(CW\*(C`EV_P_\*(C'\fR is used when other parameters are following. Example: |
4152 | \&\f(CW\*(C`EV_P_\*(C'\fR is used when other parameters are following. Example: |
… | |
… | |
3163 | \& static void cb (EV_P_ ev_timer *w, int revents) |
4159 | \& static void cb (EV_P_ ev_timer *w, int revents) |
3164 | .Ve |
4160 | .Ve |
3165 | .Sp |
4161 | .Sp |
3166 | It declares a parameter \f(CW\*(C`loop\*(C'\fR of type \f(CW\*(C`struct ev_loop *\*(C'\fR, quite |
4162 | It declares a parameter \f(CW\*(C`loop\*(C'\fR of type \f(CW\*(C`struct ev_loop *\*(C'\fR, quite |
3167 | suitable for use with \f(CW\*(C`EV_A\*(C'\fR. |
4163 | suitable for use with \f(CW\*(C`EV_A\*(C'\fR. |
3168 | .ie n .IP """EV_DEFAULT""\fR, \f(CW""EV_DEFAULT_""" 4 |
4164 | .ie n .IP """EV_DEFAULT"", ""EV_DEFAULT_""" 4 |
3169 | .el .IP "\f(CWEV_DEFAULT\fR, \f(CWEV_DEFAULT_\fR" 4 |
4165 | .el .IP "\f(CWEV_DEFAULT\fR, \f(CWEV_DEFAULT_\fR" 4 |
3170 | .IX Item "EV_DEFAULT, EV_DEFAULT_" |
4166 | .IX Item "EV_DEFAULT, EV_DEFAULT_" |
3171 | Similar to the other two macros, this gives you the value of the default |
4167 | Similar to the other two macros, this gives you the value of the default |
3172 | loop, if multiple loops are supported (\*(L"ev loop default\*(R"). |
4168 | loop, if multiple loops are supported (\*(L"ev loop default\*(R"). |
3173 | .ie n .IP """EV_DEFAULT_UC""\fR, \f(CW""EV_DEFAULT_UC_""" 4 |
4169 | .ie n .IP """EV_DEFAULT_UC"", ""EV_DEFAULT_UC_""" 4 |
3174 | .el .IP "\f(CWEV_DEFAULT_UC\fR, \f(CWEV_DEFAULT_UC_\fR" 4 |
4170 | .el .IP "\f(CWEV_DEFAULT_UC\fR, \f(CWEV_DEFAULT_UC_\fR" 4 |
3175 | .IX Item "EV_DEFAULT_UC, EV_DEFAULT_UC_" |
4171 | .IX Item "EV_DEFAULT_UC, EV_DEFAULT_UC_" |
3176 | Usage identical to \f(CW\*(C`EV_DEFAULT\*(C'\fR and \f(CW\*(C`EV_DEFAULT_\*(C'\fR, but requires that the |
4172 | Usage identical to \f(CW\*(C`EV_DEFAULT\*(C'\fR and \f(CW\*(C`EV_DEFAULT_\*(C'\fR, but requires that the |
3177 | default loop has been initialised (\f(CW\*(C`UC\*(C'\fR == unchecked). Their behaviour |
4173 | default loop has been initialised (\f(CW\*(C`UC\*(C'\fR == unchecked). Their behaviour |
3178 | is undefined when the default loop has not been initialised by a previous |
4174 | is undefined when the default loop has not been initialised by a previous |
… | |
… | |
3193 | \& } |
4189 | \& } |
3194 | \& |
4190 | \& |
3195 | \& ev_check check; |
4191 | \& ev_check check; |
3196 | \& ev_check_init (&check, check_cb); |
4192 | \& ev_check_init (&check, check_cb); |
3197 | \& ev_check_start (EV_DEFAULT_ &check); |
4193 | \& ev_check_start (EV_DEFAULT_ &check); |
3198 | \& ev_loop (EV_DEFAULT_ 0); |
4194 | \& ev_run (EV_DEFAULT_ 0); |
3199 | .Ve |
4195 | .Ve |
3200 | .SH "EMBEDDING" |
4196 | .SH "EMBEDDING" |
3201 | .IX Header "EMBEDDING" |
4197 | .IX Header "EMBEDDING" |
3202 | Libev can (and often is) directly embedded into host |
4198 | Libev can (and often is) directly embedded into host |
3203 | applications. Examples of applications that embed it include the Deliantra |
4199 | applications. Examples of applications that embed it include the Deliantra |
… | |
… | |
3206 | .PP |
4202 | .PP |
3207 | The goal is to enable you to just copy the necessary files into your |
4203 | The goal is to enable you to just copy the necessary files into your |
3208 | source directory without having to change even a single line in them, so |
4204 | source directory without having to change even a single line in them, so |
3209 | you can easily upgrade by simply copying (or having a checked-out copy of |
4205 | you can easily upgrade by simply copying (or having a checked-out copy of |
3210 | libev somewhere in your source tree). |
4206 | libev somewhere in your source tree). |
3211 | .Sh "\s-1FILESETS\s0" |
4207 | .SS "\s-1FILESETS\s0" |
3212 | .IX Subsection "FILESETS" |
4208 | .IX Subsection "FILESETS" |
3213 | Depending on what features you need you need to include one or more sets of files |
4209 | Depending on what features you need you need to include one or more sets of files |
3214 | in your application. |
4210 | in your application. |
3215 | .PP |
4211 | .PP |
3216 | \fI\s-1CORE\s0 \s-1EVENT\s0 \s-1LOOP\s0\fR |
4212 | \fI\s-1CORE\s0 \s-1EVENT\s0 \s-1LOOP\s0\fR |
… | |
… | |
3295 | For this of course you need the m4 file: |
4291 | For this of course you need the m4 file: |
3296 | .PP |
4292 | .PP |
3297 | .Vb 1 |
4293 | .Vb 1 |
3298 | \& libev.m4 |
4294 | \& libev.m4 |
3299 | .Ve |
4295 | .Ve |
3300 | .Sh "\s-1PREPROCESSOR\s0 \s-1SYMBOLS/MACROS\s0" |
4296 | .SS "\s-1PREPROCESSOR\s0 \s-1SYMBOLS/MACROS\s0" |
3301 | .IX Subsection "PREPROCESSOR SYMBOLS/MACROS" |
4297 | .IX Subsection "PREPROCESSOR SYMBOLS/MACROS" |
3302 | Libev can be configured via a variety of preprocessor symbols you have to |
4298 | Libev can be configured via a variety of preprocessor symbols you have to |
3303 | define before including any of its files. The default in the absence of |
4299 | define before including (or compiling) any of its files. The default in |
3304 | autoconf is documented for every option. |
4300 | the absence of autoconf is documented for every option. |
|
|
4301 | .PP |
|
|
4302 | Symbols marked with \*(L"(h)\*(R" do not change the \s-1ABI\s0, and can have different |
|
|
4303 | values when compiling libev vs. including \fIev.h\fR, so it is permissible |
|
|
4304 | to redefine them before including \fIev.h\fR without breaking compatibility |
|
|
4305 | to a compiled library. All other symbols change the \s-1ABI\s0, which means all |
|
|
4306 | users of libev and the libev code itself must be compiled with compatible |
|
|
4307 | settings. |
|
|
4308 | .IP "\s-1EV_COMPAT3\s0 (h)" 4 |
|
|
4309 | .IX Item "EV_COMPAT3 (h)" |
|
|
4310 | Backwards compatibility is a major concern for libev. This is why this |
|
|
4311 | release of libev comes with wrappers for the functions and symbols that |
|
|
4312 | have been renamed between libev version 3 and 4. |
|
|
4313 | .Sp |
|
|
4314 | You can disable these wrappers (to test compatibility with future |
|
|
4315 | versions) by defining \f(CW\*(C`EV_COMPAT3\*(C'\fR to \f(CW0\fR when compiling your |
|
|
4316 | sources. This has the additional advantage that you can drop the \f(CW\*(C`struct\*(C'\fR |
|
|
4317 | from \f(CW\*(C`struct ev_loop\*(C'\fR declarations, as libev will provide an \f(CW\*(C`ev_loop\*(C'\fR |
|
|
4318 | typedef in that case. |
|
|
4319 | .Sp |
|
|
4320 | In some future version, the default for \f(CW\*(C`EV_COMPAT3\*(C'\fR will become \f(CW0\fR, |
|
|
4321 | and in some even more future version the compatibility code will be |
|
|
4322 | removed completely. |
3305 | .IP "\s-1EV_STANDALONE\s0" 4 |
4323 | .IP "\s-1EV_STANDALONE\s0 (h)" 4 |
3306 | .IX Item "EV_STANDALONE" |
4324 | .IX Item "EV_STANDALONE (h)" |
3307 | Must always be \f(CW1\fR if you do not use autoconf configuration, which |
4325 | Must always be \f(CW1\fR if you do not use autoconf configuration, which |
3308 | keeps libev from including \fIconfig.h\fR, and it also defines dummy |
4326 | keeps libev from including \fIconfig.h\fR, and it also defines dummy |
3309 | implementations for some libevent functions (such as logging, which is not |
4327 | implementations for some libevent functions (such as logging, which is not |
3310 | supported). It will also not define any of the structs usually found in |
4328 | supported). It will also not define any of the structs usually found in |
3311 | \&\fIevent.h\fR that are not directly supported by the libev core alone. |
4329 | \&\fIevent.h\fR that are not directly supported by the libev core alone. |
|
|
4330 | .Sp |
|
|
4331 | In standalone mode, libev will still try to automatically deduce the |
|
|
4332 | configuration, but has to be more conservative. |
3312 | .IP "\s-1EV_USE_MONOTONIC\s0" 4 |
4333 | .IP "\s-1EV_USE_MONOTONIC\s0" 4 |
3313 | .IX Item "EV_USE_MONOTONIC" |
4334 | .IX Item "EV_USE_MONOTONIC" |
3314 | If defined to be \f(CW1\fR, libev will try to detect the availability of the |
4335 | If defined to be \f(CW1\fR, libev will try to detect the availability of the |
3315 | monotonic clock option at both compile time and runtime. Otherwise no use |
4336 | monotonic clock option at both compile time and runtime. Otherwise no |
3316 | of the monotonic clock option will be attempted. If you enable this, you |
4337 | use of the monotonic clock option will be attempted. If you enable this, |
3317 | usually have to link against librt or something similar. Enabling it when |
4338 | you usually have to link against librt or something similar. Enabling it |
3318 | the functionality isn't available is safe, though, although you have |
4339 | when the functionality isn't available is safe, though, although you have |
3319 | to make sure you link against any libraries where the \f(CW\*(C`clock_gettime\*(C'\fR |
4340 | to make sure you link against any libraries where the \f(CW\*(C`clock_gettime\*(C'\fR |
3320 | function is hiding in (often \fI\-lrt\fR). |
4341 | function is hiding in (often \fI\-lrt\fR). See also \f(CW\*(C`EV_USE_CLOCK_SYSCALL\*(C'\fR. |
3321 | .IP "\s-1EV_USE_REALTIME\s0" 4 |
4342 | .IP "\s-1EV_USE_REALTIME\s0" 4 |
3322 | .IX Item "EV_USE_REALTIME" |
4343 | .IX Item "EV_USE_REALTIME" |
3323 | If defined to be \f(CW1\fR, libev will try to detect the availability of the |
4344 | If defined to be \f(CW1\fR, libev will try to detect the availability of the |
3324 | real-time clock option at compile time (and assume its availability at |
4345 | real-time clock option at compile time (and assume its availability |
3325 | runtime if successful). Otherwise no use of the real-time clock option will |
4346 | at runtime if successful). Otherwise no use of the real-time clock |
3326 | be attempted. This effectively replaces \f(CW\*(C`gettimeofday\*(C'\fR by \f(CW\*(C`clock_get |
4347 | option will be attempted. This effectively replaces \f(CW\*(C`gettimeofday\*(C'\fR |
3327 | (CLOCK_REALTIME, ...)\*(C'\fR and will not normally affect correctness. See the |
4348 | by \f(CW\*(C`clock_get (CLOCK_REALTIME, ...)\*(C'\fR and will not normally affect |
3328 | note about libraries in the description of \f(CW\*(C`EV_USE_MONOTONIC\*(C'\fR, though. |
4349 | correctness. See the note about libraries in the description of |
|
|
4350 | \&\f(CW\*(C`EV_USE_MONOTONIC\*(C'\fR, though. Defaults to the opposite value of |
|
|
4351 | \&\f(CW\*(C`EV_USE_CLOCK_SYSCALL\*(C'\fR. |
|
|
4352 | .IP "\s-1EV_USE_CLOCK_SYSCALL\s0" 4 |
|
|
4353 | .IX Item "EV_USE_CLOCK_SYSCALL" |
|
|
4354 | If defined to be \f(CW1\fR, libev will try to use a direct syscall instead |
|
|
4355 | of calling the system-provided \f(CW\*(C`clock_gettime\*(C'\fR function. This option |
|
|
4356 | exists because on GNU/Linux, \f(CW\*(C`clock_gettime\*(C'\fR is in \f(CW\*(C`librt\*(C'\fR, but \f(CW\*(C`librt\*(C'\fR |
|
|
4357 | unconditionally pulls in \f(CW\*(C`libpthread\*(C'\fR, slowing down single-threaded |
|
|
4358 | programs needlessly. Using a direct syscall is slightly slower (in |
|
|
4359 | theory), because no optimised vdso implementation can be used, but avoids |
|
|
4360 | the pthread dependency. Defaults to \f(CW1\fR on GNU/Linux with glibc 2.x or |
|
|
4361 | higher, as it simplifies linking (no need for \f(CW\*(C`\-lrt\*(C'\fR). |
3329 | .IP "\s-1EV_USE_NANOSLEEP\s0" 4 |
4362 | .IP "\s-1EV_USE_NANOSLEEP\s0" 4 |
3330 | .IX Item "EV_USE_NANOSLEEP" |
4363 | .IX Item "EV_USE_NANOSLEEP" |
3331 | If defined to be \f(CW1\fR, libev will assume that \f(CW\*(C`nanosleep ()\*(C'\fR is available |
4364 | If defined to be \f(CW1\fR, libev will assume that \f(CW\*(C`nanosleep ()\*(C'\fR is available |
3332 | and will use it for delays. Otherwise it will use \f(CW\*(C`select ()\*(C'\fR. |
4365 | and will use it for delays. Otherwise it will use \f(CW\*(C`select ()\*(C'\fR. |
3333 | .IP "\s-1EV_USE_EVENTFD\s0" 4 |
4366 | .IP "\s-1EV_USE_EVENTFD\s0" 4 |
… | |
… | |
3345 | will not be compiled in. |
4378 | will not be compiled in. |
3346 | .IP "\s-1EV_SELECT_USE_FD_SET\s0" 4 |
4379 | .IP "\s-1EV_SELECT_USE_FD_SET\s0" 4 |
3347 | .IX Item "EV_SELECT_USE_FD_SET" |
4380 | .IX Item "EV_SELECT_USE_FD_SET" |
3348 | If defined to \f(CW1\fR, then the select backend will use the system \f(CW\*(C`fd_set\*(C'\fR |
4381 | If defined to \f(CW1\fR, then the select backend will use the system \f(CW\*(C`fd_set\*(C'\fR |
3349 | structure. This is useful if libev doesn't compile due to a missing |
4382 | structure. This is useful if libev doesn't compile due to a missing |
3350 | \&\f(CW\*(C`NFDBITS\*(C'\fR or \f(CW\*(C`fd_mask\*(C'\fR definition or it mis-guesses the bitset layout on |
4383 | \&\f(CW\*(C`NFDBITS\*(C'\fR or \f(CW\*(C`fd_mask\*(C'\fR definition or it mis-guesses the bitset layout |
3351 | exotic systems. This usually limits the range of file descriptors to some |
4384 | on exotic systems. This usually limits the range of file descriptors to |
3352 | low limit such as 1024 or might have other limitations (winsocket only |
4385 | some low limit such as 1024 or might have other limitations (winsocket |
3353 | allows 64 sockets). The \f(CW\*(C`FD_SETSIZE\*(C'\fR macro, set before compilation, might |
4386 | only allows 64 sockets). The \f(CW\*(C`FD_SETSIZE\*(C'\fR macro, set before compilation, |
3354 | influence the size of the \f(CW\*(C`fd_set\*(C'\fR used. |
4387 | configures the maximum size of the \f(CW\*(C`fd_set\*(C'\fR. |
3355 | .IP "\s-1EV_SELECT_IS_WINSOCKET\s0" 4 |
4388 | .IP "\s-1EV_SELECT_IS_WINSOCKET\s0" 4 |
3356 | .IX Item "EV_SELECT_IS_WINSOCKET" |
4389 | .IX Item "EV_SELECT_IS_WINSOCKET" |
3357 | When defined to \f(CW1\fR, the select backend will assume that |
4390 | When defined to \f(CW1\fR, the select backend will assume that |
3358 | select/socket/connect etc. don't understand file descriptors but |
4391 | select/socket/connect etc. don't understand file descriptors but |
3359 | wants osf handles on win32 (this is the case when the select to |
4392 | wants osf handles on win32 (this is the case when the select to |
3360 | be used is the winsock select). This means that it will call |
4393 | be used is the winsock select). This means that it will call |
3361 | \&\f(CW\*(C`_get_osfhandle\*(C'\fR on the fd to convert it to an \s-1OS\s0 handle. Otherwise, |
4394 | \&\f(CW\*(C`_get_osfhandle\*(C'\fR on the fd to convert it to an \s-1OS\s0 handle. Otherwise, |
3362 | it is assumed that all these functions actually work on fds, even |
4395 | it is assumed that all these functions actually work on fds, even |
3363 | on win32. Should not be defined on non\-win32 platforms. |
4396 | on win32. Should not be defined on non\-win32 platforms. |
3364 | .IP "\s-1EV_FD_TO_WIN32_HANDLE\s0" 4 |
4397 | .IP "\s-1EV_FD_TO_WIN32_HANDLE\s0(fd)" 4 |
3365 | .IX Item "EV_FD_TO_WIN32_HANDLE" |
4398 | .IX Item "EV_FD_TO_WIN32_HANDLE(fd)" |
3366 | If \f(CW\*(C`EV_SELECT_IS_WINSOCKET\*(C'\fR is enabled, then libev needs a way to map |
4399 | If \f(CW\*(C`EV_SELECT_IS_WINSOCKET\*(C'\fR is enabled, then libev needs a way to map |
3367 | file descriptors to socket handles. When not defining this symbol (the |
4400 | file descriptors to socket handles. When not defining this symbol (the |
3368 | default), then libev will call \f(CW\*(C`_get_osfhandle\*(C'\fR, which is usually |
4401 | default), then libev will call \f(CW\*(C`_get_osfhandle\*(C'\fR, which is usually |
3369 | correct. In some cases, programs use their own file descriptor management, |
4402 | correct. In some cases, programs use their own file descriptor management, |
3370 | in which case they can provide this function to map fds to socket handles. |
4403 | in which case they can provide this function to map fds to socket handles. |
|
|
4404 | .IP "\s-1EV_WIN32_HANDLE_TO_FD\s0(handle)" 4 |
|
|
4405 | .IX Item "EV_WIN32_HANDLE_TO_FD(handle)" |
|
|
4406 | If \f(CW\*(C`EV_SELECT_IS_WINSOCKET\*(C'\fR then libev maps handles to file descriptors |
|
|
4407 | using the standard \f(CW\*(C`_open_osfhandle\*(C'\fR function. For programs implementing |
|
|
4408 | their own fd to handle mapping, overwriting this function makes it easier |
|
|
4409 | to do so. This can be done by defining this macro to an appropriate value. |
|
|
4410 | .IP "\s-1EV_WIN32_CLOSE_FD\s0(fd)" 4 |
|
|
4411 | .IX Item "EV_WIN32_CLOSE_FD(fd)" |
|
|
4412 | If programs implement their own fd to handle mapping on win32, then this |
|
|
4413 | macro can be used to override the \f(CW\*(C`close\*(C'\fR function, useful to unregister |
|
|
4414 | file descriptors again. Note that the replacement function has to close |
|
|
4415 | the underlying \s-1OS\s0 handle. |
3371 | .IP "\s-1EV_USE_POLL\s0" 4 |
4416 | .IP "\s-1EV_USE_POLL\s0" 4 |
3372 | .IX Item "EV_USE_POLL" |
4417 | .IX Item "EV_USE_POLL" |
3373 | If defined to be \f(CW1\fR, libev will compile in support for the \f(CW\*(C`poll\*(C'\fR(2) |
4418 | If defined to be \f(CW1\fR, libev will compile in support for the \f(CW\*(C`poll\*(C'\fR(2) |
3374 | backend. Otherwise it will be enabled on non\-win32 platforms. It |
4419 | backend. Otherwise it will be enabled on non\-win32 platforms. It |
3375 | takes precedence over select. |
4420 | takes precedence over select. |
… | |
… | |
3414 | that you know is safe for your purposes. It is used both for signal handler \*(L"locking\*(R" |
4459 | that you know is safe for your purposes. It is used both for signal handler \*(L"locking\*(R" |
3415 | as well as for signal and thread safety in \f(CW\*(C`ev_async\*(C'\fR watchers. |
4460 | as well as for signal and thread safety in \f(CW\*(C`ev_async\*(C'\fR watchers. |
3416 | .Sp |
4461 | .Sp |
3417 | In the absence of this define, libev will use \f(CW\*(C`sig_atomic_t volatile\*(C'\fR |
4462 | In the absence of this define, libev will use \f(CW\*(C`sig_atomic_t volatile\*(C'\fR |
3418 | (from \fIsignal.h\fR), which is usually good enough on most platforms. |
4463 | (from \fIsignal.h\fR), which is usually good enough on most platforms. |
3419 | .IP "\s-1EV_H\s0" 4 |
4464 | .IP "\s-1EV_H\s0 (h)" 4 |
3420 | .IX Item "EV_H" |
4465 | .IX Item "EV_H (h)" |
3421 | The name of the \fIev.h\fR header file used to include it. The default if |
4466 | The name of the \fIev.h\fR header file used to include it. The default if |
3422 | undefined is \f(CW"ev.h"\fR in \fIevent.h\fR, \fIev.c\fR and \fIev++.h\fR. This can be |
4467 | undefined is \f(CW"ev.h"\fR in \fIevent.h\fR, \fIev.c\fR and \fIev++.h\fR. This can be |
3423 | used to virtually rename the \fIev.h\fR header file in case of conflicts. |
4468 | used to virtually rename the \fIev.h\fR header file in case of conflicts. |
3424 | .IP "\s-1EV_CONFIG_H\s0" 4 |
4469 | .IP "\s-1EV_CONFIG_H\s0 (h)" 4 |
3425 | .IX Item "EV_CONFIG_H" |
4470 | .IX Item "EV_CONFIG_H (h)" |
3426 | If \f(CW\*(C`EV_STANDALONE\*(C'\fR isn't \f(CW1\fR, this variable can be used to override |
4471 | If \f(CW\*(C`EV_STANDALONE\*(C'\fR isn't \f(CW1\fR, this variable can be used to override |
3427 | \&\fIev.c\fR's idea of where to find the \fIconfig.h\fR file, similarly to |
4472 | \&\fIev.c\fR's idea of where to find the \fIconfig.h\fR file, similarly to |
3428 | \&\f(CW\*(C`EV_H\*(C'\fR, above. |
4473 | \&\f(CW\*(C`EV_H\*(C'\fR, above. |
3429 | .IP "\s-1EV_EVENT_H\s0" 4 |
4474 | .IP "\s-1EV_EVENT_H\s0 (h)" 4 |
3430 | .IX Item "EV_EVENT_H" |
4475 | .IX Item "EV_EVENT_H (h)" |
3431 | Similarly to \f(CW\*(C`EV_H\*(C'\fR, this macro can be used to override \fIevent.c\fR's idea |
4476 | Similarly to \f(CW\*(C`EV_H\*(C'\fR, this macro can be used to override \fIevent.c\fR's idea |
3432 | of how the \fIevent.h\fR header can be found, the default is \f(CW"event.h"\fR. |
4477 | of how the \fIevent.h\fR header can be found, the default is \f(CW"event.h"\fR. |
3433 | .IP "\s-1EV_PROTOTYPES\s0" 4 |
4478 | .IP "\s-1EV_PROTOTYPES\s0 (h)" 4 |
3434 | .IX Item "EV_PROTOTYPES" |
4479 | .IX Item "EV_PROTOTYPES (h)" |
3435 | If defined to be \f(CW0\fR, then \fIev.h\fR will not define any function |
4480 | If defined to be \f(CW0\fR, then \fIev.h\fR will not define any function |
3436 | prototypes, but still define all the structs and other symbols. This is |
4481 | prototypes, but still define all the structs and other symbols. This is |
3437 | occasionally useful if you want to provide your own wrapper functions |
4482 | occasionally useful if you want to provide your own wrapper functions |
3438 | around libev functions. |
4483 | around libev functions. |
3439 | .IP "\s-1EV_MULTIPLICITY\s0" 4 |
4484 | .IP "\s-1EV_MULTIPLICITY\s0" 4 |
… | |
… | |
3459 | and time, so using the defaults of five priorities (\-2 .. +2) is usually |
4504 | and time, so using the defaults of five priorities (\-2 .. +2) is usually |
3460 | fine. |
4505 | fine. |
3461 | .Sp |
4506 | .Sp |
3462 | If your embedding application does not need any priorities, defining these |
4507 | If your embedding application does not need any priorities, defining these |
3463 | both to \f(CW0\fR will save some memory and \s-1CPU\s0. |
4508 | both to \f(CW0\fR will save some memory and \s-1CPU\s0. |
3464 | .IP "\s-1EV_PERIODIC_ENABLE\s0" 4 |
4509 | .IP "\s-1EV_PERIODIC_ENABLE\s0, \s-1EV_IDLE_ENABLE\s0, \s-1EV_EMBED_ENABLE\s0, \s-1EV_STAT_ENABLE\s0, \s-1EV_PREPARE_ENABLE\s0, \s-1EV_CHECK_ENABLE\s0, \s-1EV_FORK_ENABLE\s0, \s-1EV_SIGNAL_ENABLE\s0, \s-1EV_ASYNC_ENABLE\s0, \s-1EV_CHILD_ENABLE\s0." 4 |
3465 | .IX Item "EV_PERIODIC_ENABLE" |
4510 | .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." |
3466 | If undefined or defined to be \f(CW1\fR, then periodic timers are supported. If |
4511 | If undefined or defined to be \f(CW1\fR (and the platform supports it), then |
3467 | defined to be \f(CW0\fR, then they are not. Disabling them saves a few kB of |
4512 | the respective watcher type is supported. If defined to be \f(CW0\fR, then it |
3468 | code. |
4513 | is not. Disabling watcher types mainly saves code size. |
3469 | .IP "\s-1EV_IDLE_ENABLE\s0" 4 |
|
|
3470 | .IX Item "EV_IDLE_ENABLE" |
|
|
3471 | If undefined or defined to be \f(CW1\fR, then idle watchers are supported. If |
|
|
3472 | defined to be \f(CW0\fR, then they are not. Disabling them saves a few kB of |
|
|
3473 | code. |
|
|
3474 | .IP "\s-1EV_EMBED_ENABLE\s0" 4 |
|
|
3475 | .IX Item "EV_EMBED_ENABLE" |
|
|
3476 | If undefined or defined to be \f(CW1\fR, then embed watchers are supported. If |
|
|
3477 | defined to be \f(CW0\fR, then they are not. Embed watchers rely on most other |
|
|
3478 | watcher types, which therefore must not be disabled. |
|
|
3479 | .IP "\s-1EV_STAT_ENABLE\s0" 4 |
4514 | .IP "\s-1EV_FEATURES\s0" 4 |
3480 | .IX Item "EV_STAT_ENABLE" |
4515 | .IX Item "EV_FEATURES" |
3481 | If undefined or defined to be \f(CW1\fR, then stat watchers are supported. If |
|
|
3482 | defined to be \f(CW0\fR, then they are not. |
|
|
3483 | .IP "\s-1EV_FORK_ENABLE\s0" 4 |
|
|
3484 | .IX Item "EV_FORK_ENABLE" |
|
|
3485 | If undefined or defined to be \f(CW1\fR, then fork watchers are supported. If |
|
|
3486 | defined to be \f(CW0\fR, then they are not. |
|
|
3487 | .IP "\s-1EV_ASYNC_ENABLE\s0" 4 |
|
|
3488 | .IX Item "EV_ASYNC_ENABLE" |
|
|
3489 | If undefined or defined to be \f(CW1\fR, then async watchers are supported. If |
|
|
3490 | defined to be \f(CW0\fR, then they are not. |
|
|
3491 | .IP "\s-1EV_MINIMAL\s0" 4 |
|
|
3492 | .IX Item "EV_MINIMAL" |
|
|
3493 | If you need to shave off some kilobytes of code at the expense of some |
4516 | If you need to shave off some kilobytes of code at the expense of some |
3494 | speed, define this symbol to \f(CW1\fR. Currently this is used to override some |
4517 | speed (but with the full \s-1API\s0), you can define this symbol to request |
3495 | inlining decisions, saves roughly 30% code size on amd64. It also selects a |
4518 | certain subsets of functionality. The default is to enable all features |
3496 | much smaller 2\-heap for timer management over the default 4\-heap. |
4519 | that can be enabled on the platform. |
|
|
4520 | .Sp |
|
|
4521 | A typical way to use this symbol is to define it to \f(CW0\fR (or to a bitset |
|
|
4522 | with some broad features you want) and then selectively re-enable |
|
|
4523 | additional parts you want, for example if you want everything minimal, |
|
|
4524 | but multiple event loop support, async and child watchers and the poll |
|
|
4525 | backend, use this: |
|
|
4526 | .Sp |
|
|
4527 | .Vb 5 |
|
|
4528 | \& #define EV_FEATURES 0 |
|
|
4529 | \& #define EV_MULTIPLICITY 1 |
|
|
4530 | \& #define EV_USE_POLL 1 |
|
|
4531 | \& #define EV_CHILD_ENABLE 1 |
|
|
4532 | \& #define EV_ASYNC_ENABLE 1 |
|
|
4533 | .Ve |
|
|
4534 | .Sp |
|
|
4535 | The actual value is a bitset, it can be a combination of the following |
|
|
4536 | values: |
|
|
4537 | .RS 4 |
|
|
4538 | .ie n .IP "1 \- faster/larger code" 4 |
|
|
4539 | .el .IP "\f(CW1\fR \- faster/larger code" 4 |
|
|
4540 | .IX Item "1 - faster/larger code" |
|
|
4541 | Use larger code to speed up some operations. |
|
|
4542 | .Sp |
|
|
4543 | Currently this is used to override some inlining decisions (enlarging the |
|
|
4544 | code size by roughly 30% on amd64). |
|
|
4545 | .Sp |
|
|
4546 | When optimising for size, use of compiler flags such as \f(CW\*(C`\-Os\*(C'\fR with |
|
|
4547 | gcc is recommended, as well as \f(CW\*(C`\-DNDEBUG\*(C'\fR, as libev contains a number of |
|
|
4548 | assertions. |
|
|
4549 | .ie n .IP "2 \- faster/larger data structures" 4 |
|
|
4550 | .el .IP "\f(CW2\fR \- faster/larger data structures" 4 |
|
|
4551 | .IX Item "2 - faster/larger data structures" |
|
|
4552 | Replaces the small 2\-heap for timer management by a faster 4\-heap, larger |
|
|
4553 | hash table sizes and so on. This will usually further increase code size |
|
|
4554 | and can additionally have an effect on the size of data structures at |
|
|
4555 | runtime. |
|
|
4556 | .ie n .IP "4 \- full \s-1API\s0 configuration" 4 |
|
|
4557 | .el .IP "\f(CW4\fR \- full \s-1API\s0 configuration" 4 |
|
|
4558 | .IX Item "4 - full API configuration" |
|
|
4559 | This enables priorities (sets \f(CW\*(C`EV_MAXPRI\*(C'\fR=2 and \f(CW\*(C`EV_MINPRI\*(C'\fR=\-2), and |
|
|
4560 | enables multiplicity (\f(CW\*(C`EV_MULTIPLICITY\*(C'\fR=1). |
|
|
4561 | .ie n .IP "8 \- full \s-1API\s0" 4 |
|
|
4562 | .el .IP "\f(CW8\fR \- full \s-1API\s0" 4 |
|
|
4563 | .IX Item "8 - full API" |
|
|
4564 | This enables a lot of the \*(L"lesser used\*(R" \s-1API\s0 functions. See \f(CW\*(C`ev.h\*(C'\fR for |
|
|
4565 | details on which parts of the \s-1API\s0 are still available without this |
|
|
4566 | feature, and do not complain if this subset changes over time. |
|
|
4567 | .ie n .IP "16 \- enable all optional watcher types" 4 |
|
|
4568 | .el .IP "\f(CW16\fR \- enable all optional watcher types" 4 |
|
|
4569 | .IX Item "16 - enable all optional watcher types" |
|
|
4570 | Enables all optional watcher types. If you want to selectively enable |
|
|
4571 | only some watcher types other than I/O and timers (e.g. prepare, |
|
|
4572 | embed, async, child...) you can enable them manually by defining |
|
|
4573 | \&\f(CW\*(C`EV_watchertype_ENABLE\*(C'\fR to \f(CW1\fR instead. |
|
|
4574 | .ie n .IP "32 \- enable all backends" 4 |
|
|
4575 | .el .IP "\f(CW32\fR \- enable all backends" 4 |
|
|
4576 | .IX Item "32 - enable all backends" |
|
|
4577 | This enables all backends \- without this feature, you need to enable at |
|
|
4578 | least one backend manually (\f(CW\*(C`EV_USE_SELECT\*(C'\fR is a good choice). |
|
|
4579 | .ie n .IP "64 \- enable OS-specific ""helper"" APIs" 4 |
|
|
4580 | .el .IP "\f(CW64\fR \- enable OS-specific ``helper'' APIs" 4 |
|
|
4581 | .IX Item "64 - enable OS-specific helper APIs" |
|
|
4582 | Enable inotify, eventfd, signalfd and similar OS-specific helper APIs by |
|
|
4583 | default. |
|
|
4584 | .RE |
|
|
4585 | .RS 4 |
|
|
4586 | .Sp |
|
|
4587 | Compiling with \f(CW\*(C`gcc \-Os \-DEV_STANDALONE \-DEV_USE_EPOLL=1 \-DEV_FEATURES=0\*(C'\fR |
|
|
4588 | reduces the compiled size of libev from 24.7Kb code/2.8Kb data to 6.5Kb |
|
|
4589 | code/0.3Kb data on my GNU/Linux amd64 system, while still giving you I/O |
|
|
4590 | watchers, timers and monotonic clock support. |
|
|
4591 | .Sp |
|
|
4592 | With an intelligent-enough linker (gcc+binutils are intelligent enough |
|
|
4593 | when you use \f(CW\*(C`\-Wl,\-\-gc\-sections \-ffunction\-sections\*(C'\fR) functions unused by |
|
|
4594 | your program might be left out as well \- a binary starting a timer and an |
|
|
4595 | I/O watcher then might come out at only 5Kb. |
|
|
4596 | .RE |
|
|
4597 | .IP "\s-1EV_AVOID_STDIO\s0" 4 |
|
|
4598 | .IX Item "EV_AVOID_STDIO" |
|
|
4599 | If this is set to \f(CW1\fR at compiletime, then libev will avoid using stdio |
|
|
4600 | functions (printf, scanf, perror etc.). This will increase the code size |
|
|
4601 | somewhat, but if your program doesn't otherwise depend on stdio and your |
|
|
4602 | libc allows it, this avoids linking in the stdio library which is quite |
|
|
4603 | big. |
|
|
4604 | .Sp |
|
|
4605 | Note that error messages might become less precise when this option is |
|
|
4606 | enabled. |
|
|
4607 | .IP "\s-1EV_NSIG\s0" 4 |
|
|
4608 | .IX Item "EV_NSIG" |
|
|
4609 | The highest supported signal number, +1 (or, the number of |
|
|
4610 | signals): Normally, libev tries to deduce the maximum number of signals |
|
|
4611 | automatically, but sometimes this fails, in which case it can be |
|
|
4612 | specified. Also, using a lower number than detected (\f(CW32\fR should be |
|
|
4613 | good for about any system in existence) can save some memory, as libev |
|
|
4614 | statically allocates some 12\-24 bytes per signal number. |
3497 | .IP "\s-1EV_PID_HASHSIZE\s0" 4 |
4615 | .IP "\s-1EV_PID_HASHSIZE\s0" 4 |
3498 | .IX Item "EV_PID_HASHSIZE" |
4616 | .IX Item "EV_PID_HASHSIZE" |
3499 | \&\f(CW\*(C`ev_child\*(C'\fR watchers use a small hash table to distribute workload by |
4617 | \&\f(CW\*(C`ev_child\*(C'\fR watchers use a small hash table to distribute workload by |
3500 | pid. The default size is \f(CW16\fR (or \f(CW1\fR with \f(CW\*(C`EV_MINIMAL\*(C'\fR), usually more |
4618 | pid. The default size is \f(CW16\fR (or \f(CW1\fR with \f(CW\*(C`EV_FEATURES\*(C'\fR disabled), |
3501 | than enough. If you need to manage thousands of children you might want to |
4619 | usually more than enough. If you need to manage thousands of children you |
3502 | increase this value (\fImust\fR be a power of two). |
4620 | might want to increase this value (\fImust\fR be a power of two). |
3503 | .IP "\s-1EV_INOTIFY_HASHSIZE\s0" 4 |
4621 | .IP "\s-1EV_INOTIFY_HASHSIZE\s0" 4 |
3504 | .IX Item "EV_INOTIFY_HASHSIZE" |
4622 | .IX Item "EV_INOTIFY_HASHSIZE" |
3505 | \&\f(CW\*(C`ev_stat\*(C'\fR watchers use a small hash table to distribute workload by |
4623 | \&\f(CW\*(C`ev_stat\*(C'\fR watchers use a small hash table to distribute workload by |
3506 | inotify watch id. The default size is \f(CW16\fR (or \f(CW1\fR with \f(CW\*(C`EV_MINIMAL\*(C'\fR), |
4624 | inotify watch id. The default size is \f(CW16\fR (or \f(CW1\fR with \f(CW\*(C`EV_FEATURES\*(C'\fR |
3507 | usually more than enough. If you need to manage thousands of \f(CW\*(C`ev_stat\*(C'\fR |
4625 | disabled), usually more than enough. If you need to manage thousands of |
3508 | watchers you might want to increase this value (\fImust\fR be a power of |
4626 | \&\f(CW\*(C`ev_stat\*(C'\fR watchers you might want to increase this value (\fImust\fR be a |
3509 | two). |
4627 | power of two). |
3510 | .IP "\s-1EV_USE_4HEAP\s0" 4 |
4628 | .IP "\s-1EV_USE_4HEAP\s0" 4 |
3511 | .IX Item "EV_USE_4HEAP" |
4629 | .IX Item "EV_USE_4HEAP" |
3512 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
4630 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
3513 | timer and periodics heaps, libev uses a 4\-heap when this symbol is defined |
4631 | timer and periodics heaps, libev uses a 4\-heap when this symbol is defined |
3514 | to \f(CW1\fR. The 4\-heap uses more complicated (longer) code but has noticeably |
4632 | to \f(CW1\fR. The 4\-heap uses more complicated (longer) code but has noticeably |
3515 | faster performance with many (thousands) of watchers. |
4633 | faster performance with many (thousands) of watchers. |
3516 | .Sp |
4634 | .Sp |
3517 | The default is \f(CW1\fR unless \f(CW\*(C`EV_MINIMAL\*(C'\fR is set in which case it is \f(CW0\fR |
4635 | The default is \f(CW1\fR, unless \f(CW\*(C`EV_FEATURES\*(C'\fR overrides it, in which case it |
3518 | (disabled). |
4636 | will be \f(CW0\fR. |
3519 | .IP "\s-1EV_HEAP_CACHE_AT\s0" 4 |
4637 | .IP "\s-1EV_HEAP_CACHE_AT\s0" 4 |
3520 | .IX Item "EV_HEAP_CACHE_AT" |
4638 | .IX Item "EV_HEAP_CACHE_AT" |
3521 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
4639 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
3522 | timer and periodics heaps, libev can cache the timestamp (\fIat\fR) within |
4640 | timer and periodics heaps, libev can cache the timestamp (\fIat\fR) within |
3523 | the heap structure (selected by defining \f(CW\*(C`EV_HEAP_CACHE_AT\*(C'\fR to \f(CW1\fR), |
4641 | the heap structure (selected by defining \f(CW\*(C`EV_HEAP_CACHE_AT\*(C'\fR to \f(CW1\fR), |
3524 | which uses 8\-12 bytes more per watcher and a few hundred bytes more code, |
4642 | which uses 8\-12 bytes more per watcher and a few hundred bytes more code, |
3525 | but avoids random read accesses on heap changes. This improves performance |
4643 | but avoids random read accesses on heap changes. This improves performance |
3526 | noticeably with many (hundreds) of watchers. |
4644 | noticeably with many (hundreds) of watchers. |
3527 | .Sp |
4645 | .Sp |
3528 | The default is \f(CW1\fR unless \f(CW\*(C`EV_MINIMAL\*(C'\fR is set in which case it is \f(CW0\fR |
4646 | The default is \f(CW1\fR, unless \f(CW\*(C`EV_FEATURES\*(C'\fR overrides it, in which case it |
3529 | (disabled). |
4647 | will be \f(CW0\fR. |
3530 | .IP "\s-1EV_VERIFY\s0" 4 |
4648 | .IP "\s-1EV_VERIFY\s0" 4 |
3531 | .IX Item "EV_VERIFY" |
4649 | .IX Item "EV_VERIFY" |
3532 | Controls how much internal verification (see \f(CW\*(C`ev_loop_verify ()\*(C'\fR) will |
4650 | Controls how much internal verification (see \f(CW\*(C`ev_verify ()\*(C'\fR) will |
3533 | be done: If set to \f(CW0\fR, no internal verification code will be compiled |
4651 | be done: If set to \f(CW0\fR, no internal verification code will be compiled |
3534 | in. If set to \f(CW1\fR, then verification code will be compiled in, but not |
4652 | in. If set to \f(CW1\fR, then verification code will be compiled in, but not |
3535 | called. If set to \f(CW2\fR, then the internal verification code will be |
4653 | called. If set to \f(CW2\fR, then the internal verification code will be |
3536 | called once per loop, which can slow down libev. If set to \f(CW3\fR, then the |
4654 | called once per loop, which can slow down libev. If set to \f(CW3\fR, then the |
3537 | verification code will be called very frequently, which will slow down |
4655 | verification code will be called very frequently, which will slow down |
3538 | libev considerably. |
4656 | libev considerably. |
3539 | .Sp |
4657 | .Sp |
3540 | The default is \f(CW1\fR, unless \f(CW\*(C`EV_MINIMAL\*(C'\fR is set, in which case it will be |
4658 | The default is \f(CW1\fR, unless \f(CW\*(C`EV_FEATURES\*(C'\fR overrides it, in which case it |
3541 | \&\f(CW0\fR. |
4659 | will be \f(CW0\fR. |
3542 | .IP "\s-1EV_COMMON\s0" 4 |
4660 | .IP "\s-1EV_COMMON\s0" 4 |
3543 | .IX Item "EV_COMMON" |
4661 | .IX Item "EV_COMMON" |
3544 | By default, all watchers have a \f(CW\*(C`void *data\*(C'\fR member. By redefining |
4662 | By default, all watchers have a \f(CW\*(C`void *data\*(C'\fR member. By redefining |
3545 | this macro to a something else you can include more and other types of |
4663 | this macro to something else you can include more and other types of |
3546 | members. You have to define it each time you include one of the files, |
4664 | members. You have to define it each time you include one of the files, |
3547 | though, and it must be identical each time. |
4665 | though, and it must be identical each time. |
3548 | .Sp |
4666 | .Sp |
3549 | For example, the perl \s-1EV\s0 module uses something like this: |
4667 | For example, the perl \s-1EV\s0 module uses something like this: |
3550 | .Sp |
4668 | .Sp |
… | |
… | |
3565 | and the way callbacks are invoked and set. Must expand to a struct member |
4683 | and the way callbacks are invoked and set. Must expand to a struct member |
3566 | definition and a statement, respectively. See the \fIev.h\fR header file for |
4684 | definition and a statement, respectively. See the \fIev.h\fR header file for |
3567 | their default definitions. One possible use for overriding these is to |
4685 | their default definitions. One possible use for overriding these is to |
3568 | avoid the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument in all cases, or to use |
4686 | avoid the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument in all cases, or to use |
3569 | method calls instead of plain function calls in \*(C+. |
4687 | method calls instead of plain function calls in \*(C+. |
3570 | .Sh "\s-1EXPORTED\s0 \s-1API\s0 \s-1SYMBOLS\s0" |
4688 | .SS "\s-1EXPORTED\s0 \s-1API\s0 \s-1SYMBOLS\s0" |
3571 | .IX Subsection "EXPORTED API SYMBOLS" |
4689 | .IX Subsection "EXPORTED API SYMBOLS" |
3572 | If you need to re-export the \s-1API\s0 (e.g. via a \s-1DLL\s0) and you need a list of |
4690 | If you need to re-export the \s-1API\s0 (e.g. via a \s-1DLL\s0) and you need a list of |
3573 | exported symbols, you can use the provided \fISymbol.*\fR files which list |
4691 | exported symbols, you can use the provided \fISymbol.*\fR files which list |
3574 | all public symbols, one per line: |
4692 | all public symbols, one per line: |
3575 | .PP |
4693 | .PP |
… | |
… | |
3595 | \& #define ev_backend myprefix_ev_backend |
4713 | \& #define ev_backend myprefix_ev_backend |
3596 | \& #define ev_check_start myprefix_ev_check_start |
4714 | \& #define ev_check_start myprefix_ev_check_start |
3597 | \& #define ev_check_stop myprefix_ev_check_stop |
4715 | \& #define ev_check_stop myprefix_ev_check_stop |
3598 | \& ... |
4716 | \& ... |
3599 | .Ve |
4717 | .Ve |
3600 | .Sh "\s-1EXAMPLES\s0" |
4718 | .SS "\s-1EXAMPLES\s0" |
3601 | .IX Subsection "EXAMPLES" |
4719 | .IX Subsection "EXAMPLES" |
3602 | For a real-world example of a program the includes libev |
4720 | For a real-world example of a program the includes libev |
3603 | verbatim, you can have a look at the \s-1EV\s0 perl module |
4721 | verbatim, you can have a look at the \s-1EV\s0 perl module |
3604 | (<http://software.schmorp.de/pkg/EV.html>). It has the libev files in |
4722 | (<http://software.schmorp.de/pkg/EV.html>). It has the libev files in |
3605 | the \fIlibev/\fR subdirectory and includes them in the \fI\s-1EV/EVAPI\s0.h\fR (public |
4723 | the \fIlibev/\fR subdirectory and includes them in the \fI\s-1EV/EVAPI\s0.h\fR (public |
… | |
… | |
3608 | file. |
4726 | file. |
3609 | .PP |
4727 | .PP |
3610 | The usage in rxvt-unicode is simpler. It has a \fIev_cpp.h\fR header file |
4728 | The usage in rxvt-unicode is simpler. It has a \fIev_cpp.h\fR header file |
3611 | that everybody includes and which overrides some configure choices: |
4729 | that everybody includes and which overrides some configure choices: |
3612 | .PP |
4730 | .PP |
3613 | .Vb 9 |
4731 | .Vb 8 |
3614 | \& #define EV_MINIMAL 1 |
4732 | \& #define EV_FEATURES 8 |
3615 | \& #define EV_USE_POLL 0 |
4733 | \& #define EV_USE_SELECT 1 |
3616 | \& #define EV_MULTIPLICITY 0 |
|
|
3617 | \& #define EV_PERIODIC_ENABLE 0 |
4734 | \& #define EV_PREPARE_ENABLE 1 |
|
|
4735 | \& #define EV_IDLE_ENABLE 1 |
3618 | \& #define EV_STAT_ENABLE 0 |
4736 | \& #define EV_SIGNAL_ENABLE 1 |
3619 | \& #define EV_FORK_ENABLE 0 |
4737 | \& #define EV_CHILD_ENABLE 1 |
|
|
4738 | \& #define EV_USE_STDEXCEPT 0 |
3620 | \& #define EV_CONFIG_H <config.h> |
4739 | \& #define EV_CONFIG_H <config.h> |
3621 | \& #define EV_MINPRI 0 |
|
|
3622 | \& #define EV_MAXPRI 0 |
|
|
3623 | \& |
4740 | \& |
3624 | \& #include "ev++.h" |
4741 | \& #include "ev++.h" |
3625 | .Ve |
4742 | .Ve |
3626 | .PP |
4743 | .PP |
3627 | And a \fIev_cpp.C\fR implementation file that contains libev proper and is compiled: |
4744 | And a \fIev_cpp.C\fR implementation file that contains libev proper and is compiled: |
3628 | .PP |
4745 | .PP |
3629 | .Vb 2 |
4746 | .Vb 2 |
3630 | \& #include "ev_cpp.h" |
4747 | \& #include "ev_cpp.h" |
3631 | \& #include "ev.c" |
4748 | \& #include "ev.c" |
3632 | .Ve |
4749 | .Ve |
3633 | .SH "INTERACTION WITH OTHER PROGRAMS OR LIBRARIES" |
4750 | .SH "INTERACTION WITH OTHER PROGRAMS, LIBRARIES OR THE ENVIRONMENT" |
3634 | .IX Header "INTERACTION WITH OTHER PROGRAMS OR LIBRARIES" |
4751 | .IX Header "INTERACTION WITH OTHER PROGRAMS, LIBRARIES OR THE ENVIRONMENT" |
3635 | .Sh "\s-1THREADS\s0 \s-1AND\s0 \s-1COROUTINES\s0" |
4752 | .SS "\s-1THREADS\s0 \s-1AND\s0 \s-1COROUTINES\s0" |
3636 | .IX Subsection "THREADS AND COROUTINES" |
4753 | .IX Subsection "THREADS AND COROUTINES" |
3637 | \fI\s-1THREADS\s0\fR |
4754 | \fI\s-1THREADS\s0\fR |
3638 | .IX Subsection "THREADS" |
4755 | .IX Subsection "THREADS" |
3639 | .PP |
4756 | .PP |
3640 | All libev functions are reentrant and thread-safe unless explicitly |
4757 | All libev functions are reentrant and thread-safe unless explicitly |
… | |
… | |
3686 | An example use would be to communicate signals or other events that only |
4803 | An example use would be to communicate signals or other events that only |
3687 | work in the default loop by registering the signal watcher with the |
4804 | work in the default loop by registering the signal watcher with the |
3688 | default loop and triggering an \f(CW\*(C`ev_async\*(C'\fR watcher from the default loop |
4805 | default loop and triggering an \f(CW\*(C`ev_async\*(C'\fR watcher from the default loop |
3689 | watcher callback into the event loop interested in the signal. |
4806 | watcher callback into the event loop interested in the signal. |
3690 | .PP |
4807 | .PP |
|
|
4808 | See also \*(L"\s-1THREAD\s0 \s-1LOCKING\s0 \s-1EXAMPLE\s0\*(R". |
|
|
4809 | .PP |
3691 | \fI\s-1COROUTINES\s0\fR |
4810 | \fI\s-1COROUTINES\s0\fR |
3692 | .IX Subsection "COROUTINES" |
4811 | .IX Subsection "COROUTINES" |
3693 | .PP |
4812 | .PP |
3694 | Libev is very accommodating to coroutines (\*(L"cooperative threads\*(R"): |
4813 | Libev is very accommodating to coroutines (\*(L"cooperative threads\*(R"): |
3695 | libev fully supports nesting calls to its functions from different |
4814 | libev fully supports nesting calls to its functions from different |
3696 | coroutines (e.g. you can call \f(CW\*(C`ev_loop\*(C'\fR on the same loop from two |
4815 | coroutines (e.g. you can call \f(CW\*(C`ev_run\*(C'\fR on the same loop from two |
3697 | different coroutines, and switch freely between both coroutines running the |
4816 | different coroutines, and switch freely between both coroutines running |
3698 | loop, as long as you don't confuse yourself). The only exception is that |
4817 | the loop, as long as you don't confuse yourself). The only exception is |
3699 | you must not do this from \f(CW\*(C`ev_periodic\*(C'\fR reschedule callbacks. |
4818 | that you must not do this from \f(CW\*(C`ev_periodic\*(C'\fR reschedule callbacks. |
3700 | .PP |
4819 | .PP |
3701 | Care has been taken to ensure that libev does not keep local state inside |
4820 | Care has been taken to ensure that libev does not keep local state inside |
3702 | \&\f(CW\*(C`ev_loop\*(C'\fR, and other calls do not usually allow for coroutine switches as |
4821 | \&\f(CW\*(C`ev_run\*(C'\fR, and other calls do not usually allow for coroutine switches as |
3703 | they do not call any callbacks. |
4822 | they do not call any callbacks. |
3704 | .Sh "\s-1COMPILER\s0 \s-1WARNINGS\s0" |
4823 | .SS "\s-1COMPILER\s0 \s-1WARNINGS\s0" |
3705 | .IX Subsection "COMPILER WARNINGS" |
4824 | .IX Subsection "COMPILER WARNINGS" |
3706 | Depending on your compiler and compiler settings, you might get no or a |
4825 | Depending on your compiler and compiler settings, you might get no or a |
3707 | lot of warnings when compiling libev code. Some people are apparently |
4826 | lot of warnings when compiling libev code. Some people are apparently |
3708 | scared by this. |
4827 | scared by this. |
3709 | .PP |
4828 | .PP |
… | |
… | |
3717 | maintainable. |
4836 | maintainable. |
3718 | .PP |
4837 | .PP |
3719 | And of course, some compiler warnings are just plain stupid, or simply |
4838 | And of course, some compiler warnings are just plain stupid, or simply |
3720 | wrong (because they don't actually warn about the condition their message |
4839 | wrong (because they don't actually warn about the condition their message |
3721 | seems to warn about). For example, certain older gcc versions had some |
4840 | seems to warn about). For example, certain older gcc versions had some |
3722 | warnings that resulted an extreme number of false positives. These have |
4841 | warnings that resulted in an extreme number of false positives. These have |
3723 | been fixed, but some people still insist on making code warn-free with |
4842 | been fixed, but some people still insist on making code warn-free with |
3724 | such buggy versions. |
4843 | such buggy versions. |
3725 | .PP |
4844 | .PP |
3726 | While libev is written to generate as few warnings as possible, |
4845 | While libev is written to generate as few warnings as possible, |
3727 | \&\*(L"warn-free\*(R" code is not a goal, and it is recommended not to build libev |
4846 | \&\*(L"warn-free\*(R" code is not a goal, and it is recommended not to build libev |
3728 | with any compiler warnings enabled unless you are prepared to cope with |
4847 | with any compiler warnings enabled unless you are prepared to cope with |
3729 | them (e.g. by ignoring them). Remember that warnings are just that: |
4848 | them (e.g. by ignoring them). Remember that warnings are just that: |
3730 | warnings, not errors, or proof of bugs. |
4849 | warnings, not errors, or proof of bugs. |
3731 | .Sh "\s-1VALGRIND\s0" |
4850 | .SS "\s-1VALGRIND\s0" |
3732 | .IX Subsection "VALGRIND" |
4851 | .IX Subsection "VALGRIND" |
3733 | Valgrind has a special section here because it is a popular tool that is |
4852 | Valgrind has a special section here because it is a popular tool that is |
3734 | highly useful. Unfortunately, valgrind reports are very hard to interpret. |
4853 | highly useful. Unfortunately, valgrind reports are very hard to interpret. |
3735 | .PP |
4854 | .PP |
3736 | If you think you found a bug (memory leak, uninitialised data access etc.) |
4855 | If you think you found a bug (memory leak, uninitialised data access etc.) |
… | |
… | |
3761 | .PP |
4880 | .PP |
3762 | If you need, for some reason, empty reports from valgrind for your project |
4881 | If you need, for some reason, empty reports from valgrind for your project |
3763 | I suggest using suppression lists. |
4882 | I suggest using suppression lists. |
3764 | .SH "PORTABILITY NOTES" |
4883 | .SH "PORTABILITY NOTES" |
3765 | .IX Header "PORTABILITY NOTES" |
4884 | .IX Header "PORTABILITY NOTES" |
|
|
4885 | .SS "\s-1GNU/LINUX\s0 32 \s-1BIT\s0 \s-1LIMITATIONS\s0" |
|
|
4886 | .IX Subsection "GNU/LINUX 32 BIT LIMITATIONS" |
|
|
4887 | GNU/Linux is the only common platform that supports 64 bit file/large file |
|
|
4888 | interfaces but \fIdisables\fR them by default. |
|
|
4889 | .PP |
|
|
4890 | That means that libev compiled in the default environment doesn't support |
|
|
4891 | files larger than 2GiB or so, which mainly affects \f(CW\*(C`ev_stat\*(C'\fR watchers. |
|
|
4892 | .PP |
|
|
4893 | Unfortunately, many programs try to work around this GNU/Linux issue |
|
|
4894 | by enabling the large file \s-1API\s0, which makes them incompatible with the |
|
|
4895 | standard libev compiled for their system. |
|
|
4896 | .PP |
|
|
4897 | Likewise, libev cannot enable the large file \s-1API\s0 itself as this would |
|
|
4898 | suddenly make it incompatible to the default compile time environment, |
|
|
4899 | i.e. all programs not using special compile switches. |
|
|
4900 | .SS "\s-1OS/X\s0 \s-1AND\s0 \s-1DARWIN\s0 \s-1BUGS\s0" |
|
|
4901 | .IX Subsection "OS/X AND DARWIN BUGS" |
|
|
4902 | The whole thing is a bug if you ask me \- basically any system interface |
|
|
4903 | you touch is broken, whether it is locales, poll, kqueue or even the |
|
|
4904 | OpenGL drivers. |
|
|
4905 | .PP |
|
|
4906 | \fI\f(CI\*(C`kqueue\*(C'\fI is buggy\fR |
|
|
4907 | .IX Subsection "kqueue is buggy" |
|
|
4908 | .PP |
|
|
4909 | The kqueue syscall is broken in all known versions \- most versions support |
|
|
4910 | only sockets, many support pipes. |
|
|
4911 | .PP |
|
|
4912 | Libev tries to work around this by not using \f(CW\*(C`kqueue\*(C'\fR by default on this |
|
|
4913 | rotten platform, but of course you can still ask for it when creating a |
|
|
4914 | loop \- embedding a socket-only kqueue loop into a select-based one is |
|
|
4915 | probably going to work well. |
|
|
4916 | .PP |
|
|
4917 | \fI\f(CI\*(C`poll\*(C'\fI is buggy\fR |
|
|
4918 | .IX Subsection "poll is buggy" |
|
|
4919 | .PP |
|
|
4920 | Instead of fixing \f(CW\*(C`kqueue\*(C'\fR, Apple replaced their (working) \f(CW\*(C`poll\*(C'\fR |
|
|
4921 | implementation by something calling \f(CW\*(C`kqueue\*(C'\fR internally around the 10.5.6 |
|
|
4922 | release, so now \f(CW\*(C`kqueue\*(C'\fR \fIand\fR \f(CW\*(C`poll\*(C'\fR are broken. |
|
|
4923 | .PP |
|
|
4924 | Libev tries to work around this by not using \f(CW\*(C`poll\*(C'\fR by default on |
|
|
4925 | this rotten platform, but of course you can still ask for it when creating |
|
|
4926 | a loop. |
|
|
4927 | .PP |
|
|
4928 | \fI\f(CI\*(C`select\*(C'\fI is buggy\fR |
|
|
4929 | .IX Subsection "select is buggy" |
|
|
4930 | .PP |
|
|
4931 | All that's left is \f(CW\*(C`select\*(C'\fR, and of course Apple found a way to fuck this |
|
|
4932 | one up as well: On \s-1OS/X\s0, \f(CW\*(C`select\*(C'\fR actively limits the number of file |
|
|
4933 | descriptors you can pass in to 1024 \- your program suddenly crashes when |
|
|
4934 | you use more. |
|
|
4935 | .PP |
|
|
4936 | There is an undocumented \*(L"workaround\*(R" for this \- defining |
|
|
4937 | \&\f(CW\*(C`_DARWIN_UNLIMITED_SELECT\*(C'\fR, which libev tries to use, so select \fIshould\fR |
|
|
4938 | work on \s-1OS/X\s0. |
|
|
4939 | .SS "\s-1SOLARIS\s0 \s-1PROBLEMS\s0 \s-1AND\s0 \s-1WORKAROUNDS\s0" |
|
|
4940 | .IX Subsection "SOLARIS PROBLEMS AND WORKAROUNDS" |
|
|
4941 | \fI\f(CI\*(C`errno\*(C'\fI reentrancy\fR |
|
|
4942 | .IX Subsection "errno reentrancy" |
|
|
4943 | .PP |
|
|
4944 | The default compile environment on Solaris is unfortunately so |
|
|
4945 | thread-unsafe that you can't even use components/libraries compiled |
|
|
4946 | without \f(CW\*(C`\-D_REENTRANT\*(C'\fR in a threaded program, which, of course, isn't |
|
|
4947 | defined by default. A valid, if stupid, implementation choice. |
|
|
4948 | .PP |
|
|
4949 | If you want to use libev in threaded environments you have to make sure |
|
|
4950 | it's compiled with \f(CW\*(C`_REENTRANT\*(C'\fR defined. |
|
|
4951 | .PP |
|
|
4952 | \fIEvent port backend\fR |
|
|
4953 | .IX Subsection "Event port backend" |
|
|
4954 | .PP |
|
|
4955 | The scalable event interface for Solaris is called \*(L"event |
|
|
4956 | ports\*(R". Unfortunately, this mechanism is very buggy in all major |
|
|
4957 | releases. If you run into high \s-1CPU\s0 usage, your program freezes or you get |
|
|
4958 | a large number of spurious wakeups, make sure you have all the relevant |
|
|
4959 | and latest kernel patches applied. No, I don't know which ones, but there |
|
|
4960 | are multiple ones to apply, and afterwards, event ports actually work |
|
|
4961 | great. |
|
|
4962 | .PP |
|
|
4963 | If you can't get it to work, you can try running the program by setting |
|
|
4964 | the environment variable \f(CW\*(C`LIBEV_FLAGS=3\*(C'\fR to only allow \f(CW\*(C`poll\*(C'\fR and |
|
|
4965 | \&\f(CW\*(C`select\*(C'\fR backends. |
|
|
4966 | .SS "\s-1AIX\s0 \s-1POLL\s0 \s-1BUG\s0" |
|
|
4967 | .IX Subsection "AIX POLL BUG" |
|
|
4968 | \&\s-1AIX\s0 unfortunately has a broken \f(CW\*(C`poll.h\*(C'\fR header. Libev works around |
|
|
4969 | this by trying to avoid the poll backend altogether (i.e. it's not even |
|
|
4970 | compiled in), which normally isn't a big problem as \f(CW\*(C`select\*(C'\fR works fine |
|
|
4971 | with large bitsets on \s-1AIX\s0, and \s-1AIX\s0 is dead anyway. |
3766 | .Sh "\s-1WIN32\s0 \s-1PLATFORM\s0 \s-1LIMITATIONS\s0 \s-1AND\s0 \s-1WORKAROUNDS\s0" |
4972 | .SS "\s-1WIN32\s0 \s-1PLATFORM\s0 \s-1LIMITATIONS\s0 \s-1AND\s0 \s-1WORKAROUNDS\s0" |
3767 | .IX Subsection "WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS" |
4973 | .IX Subsection "WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS" |
|
|
4974 | \fIGeneral issues\fR |
|
|
4975 | .IX Subsection "General issues" |
|
|
4976 | .PP |
3768 | Win32 doesn't support any of the standards (e.g. \s-1POSIX\s0) that libev |
4977 | Win32 doesn't support any of the standards (e.g. \s-1POSIX\s0) that libev |
3769 | requires, and its I/O model is fundamentally incompatible with the \s-1POSIX\s0 |
4978 | requires, and its I/O model is fundamentally incompatible with the \s-1POSIX\s0 |
3770 | model. Libev still offers limited functionality on this platform in |
4979 | model. Libev still offers limited functionality on this platform in |
3771 | the form of the \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR backend, and only supports socket |
4980 | the form of the \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR backend, and only supports socket |
3772 | descriptors. This only applies when using Win32 natively, not when using |
4981 | descriptors. This only applies when using Win32 natively, not when using |
3773 | e.g. cygwin. |
4982 | e.g. cygwin. Actually, it only applies to the microsofts own compilers, |
|
|
4983 | as every compielr comes with a slightly differently broken/incompatible |
|
|
4984 | environment. |
3774 | .PP |
4985 | .PP |
3775 | Lifting these limitations would basically require the full |
4986 | Lifting these limitations would basically require the full |
3776 | re-implementation of the I/O system. If you are into these kinds of |
4987 | re-implementation of the I/O system. If you are into this kind of thing, |
3777 | things, then note that glib does exactly that for you in a very portable |
4988 | then note that glib does exactly that for you in a very portable way (note |
3778 | way (note also that glib is the slowest event library known to man). |
4989 | also that glib is the slowest event library known to man). |
3779 | .PP |
4990 | .PP |
3780 | There is no supported compilation method available on windows except |
4991 | There is no supported compilation method available on windows except |
3781 | embedding it into other applications. |
4992 | embedding it into other applications. |
|
|
4993 | .PP |
|
|
4994 | Sensible signal handling is officially unsupported by Microsoft \- libev |
|
|
4995 | tries its best, but under most conditions, signals will simply not work. |
3782 | .PP |
4996 | .PP |
3783 | Not a libev limitation but worth mentioning: windows apparently doesn't |
4997 | Not a libev limitation but worth mentioning: windows apparently doesn't |
3784 | accept large writes: instead of resulting in a partial write, windows will |
4998 | accept large writes: instead of resulting in a partial write, windows will |
3785 | either accept everything or return \f(CW\*(C`ENOBUFS\*(C'\fR if the buffer is too large, |
4999 | either accept everything or return \f(CW\*(C`ENOBUFS\*(C'\fR if the buffer is too large, |
3786 | so make sure you only write small amounts into your sockets (less than a |
5000 | so make sure you only write small amounts into your sockets (less than a |
… | |
… | |
3791 | the abysmal performance of winsockets, using a large number of sockets |
5005 | the abysmal performance of winsockets, using a large number of sockets |
3792 | is not recommended (and not reasonable). If your program needs to use |
5006 | is not recommended (and not reasonable). If your program needs to use |
3793 | more than a hundred or so sockets, then likely it needs to use a totally |
5007 | more than a hundred or so sockets, then likely it needs to use a totally |
3794 | different implementation for windows, as libev offers the \s-1POSIX\s0 readiness |
5008 | different implementation for windows, as libev offers the \s-1POSIX\s0 readiness |
3795 | notification model, which cannot be implemented efficiently on windows |
5009 | notification model, which cannot be implemented efficiently on windows |
3796 | (Microsoft monopoly games). |
5010 | (due to Microsoft monopoly games). |
3797 | .PP |
5011 | .PP |
3798 | A typical way to use libev under windows is to embed it (see the embedding |
5012 | A typical way to use libev under windows is to embed it (see the embedding |
3799 | section for details) and use the following \fIevwrap.h\fR header file instead |
5013 | section for details) and use the following \fIevwrap.h\fR header file instead |
3800 | of \fIev.h\fR: |
5014 | of \fIev.h\fR: |
3801 | .PP |
5015 | .PP |
… | |
… | |
3811 | .PP |
5025 | .PP |
3812 | .Vb 2 |
5026 | .Vb 2 |
3813 | \& #include "evwrap.h" |
5027 | \& #include "evwrap.h" |
3814 | \& #include "ev.c" |
5028 | \& #include "ev.c" |
3815 | .Ve |
5029 | .Ve |
3816 | .IP "The winsocket select function" 4 |
5030 | .PP |
|
|
5031 | \fIThe winsocket \f(CI\*(C`select\*(C'\fI function\fR |
3817 | .IX Item "The winsocket select function" |
5032 | .IX Subsection "The winsocket select function" |
|
|
5033 | .PP |
3818 | The winsocket \f(CW\*(C`select\*(C'\fR function doesn't follow \s-1POSIX\s0 in that it |
5034 | The winsocket \f(CW\*(C`select\*(C'\fR function doesn't follow \s-1POSIX\s0 in that it |
3819 | requires socket \fIhandles\fR and not socket \fIfile descriptors\fR (it is |
5035 | requires socket \fIhandles\fR and not socket \fIfile descriptors\fR (it is |
3820 | also extremely buggy). This makes select very inefficient, and also |
5036 | also extremely buggy). This makes select very inefficient, and also |
3821 | requires a mapping from file descriptors to socket handles (the Microsoft |
5037 | requires a mapping from file descriptors to socket handles (the Microsoft |
3822 | C runtime provides the function \f(CW\*(C`_open_osfhandle\*(C'\fR for this). See the |
5038 | C runtime provides the function \f(CW\*(C`_open_osfhandle\*(C'\fR for this). See the |
3823 | discussion of the \f(CW\*(C`EV_SELECT_USE_FD_SET\*(C'\fR, \f(CW\*(C`EV_SELECT_IS_WINSOCKET\*(C'\fR and |
5039 | discussion of the \f(CW\*(C`EV_SELECT_USE_FD_SET\*(C'\fR, \f(CW\*(C`EV_SELECT_IS_WINSOCKET\*(C'\fR and |
3824 | \&\f(CW\*(C`EV_FD_TO_WIN32_HANDLE\*(C'\fR preprocessor symbols for more info. |
5040 | \&\f(CW\*(C`EV_FD_TO_WIN32_HANDLE\*(C'\fR preprocessor symbols for more info. |
3825 | .Sp |
5041 | .PP |
3826 | The configuration for a \*(L"naked\*(R" win32 using the Microsoft runtime |
5042 | The configuration for a \*(L"naked\*(R" win32 using the Microsoft runtime |
3827 | libraries and raw winsocket select is: |
5043 | libraries and raw winsocket select is: |
3828 | .Sp |
5044 | .PP |
3829 | .Vb 2 |
5045 | .Vb 2 |
3830 | \& #define EV_USE_SELECT 1 |
5046 | \& #define EV_USE_SELECT 1 |
3831 | \& #define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */ |
5047 | \& #define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */ |
3832 | .Ve |
5048 | .Ve |
3833 | .Sp |
5049 | .PP |
3834 | Note that winsockets handling of fd sets is O(n), so you can easily get a |
5050 | Note that winsockets handling of fd sets is O(n), so you can easily get a |
3835 | complexity in the O(nA\*^X) range when using win32. |
5051 | complexity in the O(nA\*^X) range when using win32. |
|
|
5052 | .PP |
3836 | .IP "Limited number of file descriptors" 4 |
5053 | \fILimited number of file descriptors\fR |
3837 | .IX Item "Limited number of file descriptors" |
5054 | .IX Subsection "Limited number of file descriptors" |
|
|
5055 | .PP |
3838 | Windows has numerous arbitrary (and low) limits on things. |
5056 | Windows has numerous arbitrary (and low) limits on things. |
3839 | .Sp |
5057 | .PP |
3840 | Early versions of winsocket's select only supported waiting for a maximum |
5058 | Early versions of winsocket's select only supported waiting for a maximum |
3841 | of \f(CW64\fR handles (probably owning to the fact that all windows kernels |
5059 | of \f(CW64\fR handles (probably owning to the fact that all windows kernels |
3842 | can only wait for \f(CW64\fR things at the same time internally; Microsoft |
5060 | can only wait for \f(CW64\fR things at the same time internally; Microsoft |
3843 | recommends spawning a chain of threads and wait for 63 handles and the |
5061 | recommends spawning a chain of threads and wait for 63 handles and the |
3844 | previous thread in each. Great). |
5062 | previous thread in each. Sounds great!). |
3845 | .Sp |
5063 | .PP |
3846 | Newer versions support more handles, but you need to define \f(CW\*(C`FD_SETSIZE\*(C'\fR |
5064 | Newer versions support more handles, but you need to define \f(CW\*(C`FD_SETSIZE\*(C'\fR |
3847 | to some high number (e.g. \f(CW2048\fR) before compiling the winsocket select |
5065 | to some high number (e.g. \f(CW2048\fR) before compiling the winsocket select |
3848 | call (which might be in libev or elsewhere, for example, perl does its own |
5066 | call (which might be in libev or elsewhere, for example, perl and many |
3849 | select emulation on windows). |
5067 | other interpreters do their own select emulation on windows). |
3850 | .Sp |
5068 | .PP |
3851 | Another limit is the number of file descriptors in the Microsoft runtime |
5069 | Another limit is the number of file descriptors in the Microsoft runtime |
3852 | libraries, which by default is \f(CW64\fR (there must be a hidden \fI64\fR fetish |
5070 | libraries, which by default is \f(CW64\fR (there must be a hidden \fI64\fR |
3853 | or something like this inside Microsoft). You can increase this by calling |
5071 | fetish or something like this inside Microsoft). You can increase this |
3854 | \&\f(CW\*(C`_setmaxstdio\*(C'\fR, which can increase this limit to \f(CW2048\fR (another |
5072 | by calling \f(CW\*(C`_setmaxstdio\*(C'\fR, which can increase this limit to \f(CW2048\fR |
3855 | arbitrary limit), but is broken in many versions of the Microsoft runtime |
5073 | (another arbitrary limit), but is broken in many versions of the Microsoft |
3856 | libraries. |
|
|
3857 | .Sp |
|
|
3858 | This might get you to about \f(CW512\fR or \f(CW2048\fR sockets (depending on |
5074 | runtime libraries. This might get you to about \f(CW512\fR or \f(CW2048\fR sockets |
3859 | windows version and/or the phase of the moon). To get more, you need to |
5075 | (depending on windows version and/or the phase of the moon). To get more, |
3860 | wrap all I/O functions and provide your own fd management, but the cost of |
5076 | you need to wrap all I/O functions and provide your own fd management, but |
3861 | calling select (O(nA\*^X)) will likely make this unworkable. |
5077 | the cost of calling select (O(nA\*^X)) will likely make this unworkable. |
3862 | .Sh "\s-1PORTABILITY\s0 \s-1REQUIREMENTS\s0" |
5078 | .SS "\s-1PORTABILITY\s0 \s-1REQUIREMENTS\s0" |
3863 | .IX Subsection "PORTABILITY REQUIREMENTS" |
5079 | .IX Subsection "PORTABILITY REQUIREMENTS" |
3864 | In addition to a working ISO-C implementation and of course the |
5080 | In addition to a working ISO-C implementation and of course the |
3865 | backend-specific APIs, libev relies on a few additional extensions: |
5081 | backend-specific APIs, libev relies on a few additional extensions: |
3866 | .ie n .IP """void (*)(ev_watcher_type *, int revents)""\fR must have compatible calling conventions regardless of \f(CW""ev_watcher_type *""." 4 |
5082 | .ie n .IP """void (*)(ev_watcher_type *, int revents)"" must have compatible calling conventions regardless of ""ev_watcher_type *""." 4 |
3867 | .el .IP "\f(CWvoid (*)(ev_watcher_type *, int revents)\fR must have compatible calling conventions regardless of \f(CWev_watcher_type *\fR." 4 |
5083 | .el .IP "\f(CWvoid (*)(ev_watcher_type *, int revents)\fR must have compatible calling conventions regardless of \f(CWev_watcher_type *\fR." 4 |
3868 | .IX Item "void (*)(ev_watcher_type *, int revents) must have compatible calling conventions regardless of ev_watcher_type *." |
5084 | .IX Item "void (*)(ev_watcher_type *, int revents) must have compatible calling conventions regardless of ev_watcher_type *." |
3869 | Libev assumes not only that all watcher pointers have the same internal |
5085 | Libev assumes not only that all watcher pointers have the same internal |
3870 | structure (guaranteed by \s-1POSIX\s0 but not by \s-1ISO\s0 C for example), but it also |
5086 | structure (guaranteed by \s-1POSIX\s0 but not by \s-1ISO\s0 C for example), but it also |
3871 | assumes that the same (machine) code can be used to call any watcher |
5087 | assumes that the same (machine) code can be used to call any watcher |
3872 | callback: The watcher callbacks have different type signatures, but libev |
5088 | callback: The watcher callbacks have different type signatures, but libev |
3873 | calls them using an \f(CW\*(C`ev_watcher *\*(C'\fR internally. |
5089 | calls them using an \f(CW\*(C`ev_watcher *\*(C'\fR internally. |
|
|
5090 | .IP "pointer accesses must be thread-atomic" 4 |
|
|
5091 | .IX Item "pointer accesses must be thread-atomic" |
|
|
5092 | Accessing a pointer value must be atomic, it must both be readable and |
|
|
5093 | writable in one piece \- this is the case on all current architectures. |
3874 | .ie n .IP """sig_atomic_t volatile"" must be thread-atomic as well" 4 |
5094 | .ie n .IP """sig_atomic_t volatile"" must be thread-atomic as well" 4 |
3875 | .el .IP "\f(CWsig_atomic_t volatile\fR must be thread-atomic as well" 4 |
5095 | .el .IP "\f(CWsig_atomic_t volatile\fR must be thread-atomic as well" 4 |
3876 | .IX Item "sig_atomic_t volatile must be thread-atomic as well" |
5096 | .IX Item "sig_atomic_t volatile must be thread-atomic as well" |
3877 | The type \f(CW\*(C`sig_atomic_t volatile\*(C'\fR (or whatever is defined as |
5097 | The type \f(CW\*(C`sig_atomic_t volatile\*(C'\fR (or whatever is defined as |
3878 | \&\f(CW\*(C`EV_ATOMIC_T\*(C'\fR) must be atomic with respect to accesses from different |
5098 | \&\f(CW\*(C`EV_ATOMIC_T\*(C'\fR) must be atomic with respect to accesses from different |
… | |
… | |
3901 | watchers. |
5121 | watchers. |
3902 | .ie n .IP """double"" must hold a time value in seconds with enough accuracy" 4 |
5122 | .ie n .IP """double"" must hold a time value in seconds with enough accuracy" 4 |
3903 | .el .IP "\f(CWdouble\fR must hold a time value in seconds with enough accuracy" 4 |
5123 | .el .IP "\f(CWdouble\fR must hold a time value in seconds with enough accuracy" 4 |
3904 | .IX Item "double must hold a time value in seconds with enough accuracy" |
5124 | .IX Item "double must hold a time value in seconds with enough accuracy" |
3905 | The type \f(CW\*(C`double\*(C'\fR is used to represent timestamps. It is required to |
5125 | The type \f(CW\*(C`double\*(C'\fR is used to represent timestamps. It is required to |
3906 | have at least 51 bits of mantissa (and 9 bits of exponent), which is good |
5126 | have at least 51 bits of mantissa (and 9 bits of exponent), which is |
3907 | enough for at least into the year 4000. This requirement is fulfilled by |
5127 | good enough for at least into the year 4000 with millisecond accuracy |
|
|
5128 | (the design goal for libev). This requirement is overfulfilled by |
3908 | implementations implementing \s-1IEEE\s0 754 (basically all existing ones). |
5129 | implementations using \s-1IEEE\s0 754, which is basically all existing ones. With |
|
|
5130 | \&\s-1IEEE\s0 754 doubles, you get microsecond accuracy until at least 2200. |
3909 | .PP |
5131 | .PP |
3910 | If you know of other additional requirements drop me a note. |
5132 | If you know of other additional requirements drop me a note. |
3911 | .SH "ALGORITHMIC COMPLEXITIES" |
5133 | .SH "ALGORITHMIC COMPLEXITIES" |
3912 | .IX Header "ALGORITHMIC COMPLEXITIES" |
5134 | .IX Header "ALGORITHMIC COMPLEXITIES" |
3913 | In this section the complexities of (many of) the algorithms used inside |
5135 | In this section the complexities of (many of) the algorithms used inside |
… | |
… | |
3969 | .IX Item "Processing signals: O(max_signal_number)" |
5191 | .IX Item "Processing signals: O(max_signal_number)" |
3970 | .PD |
5192 | .PD |
3971 | Sending involves a system call \fIiff\fR there were no other \f(CW\*(C`ev_async_send\*(C'\fR |
5193 | Sending involves a system call \fIiff\fR there were no other \f(CW\*(C`ev_async_send\*(C'\fR |
3972 | calls in the current loop iteration. Checking for async and signal events |
5194 | calls in the current loop iteration. Checking for async and signal events |
3973 | involves iterating over all running async watchers or all signal numbers. |
5195 | involves iterating over all running async watchers or all signal numbers. |
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|
5196 | .SH "PORTING FROM LIBEV 3.X TO 4.X" |
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|
5197 | .IX Header "PORTING FROM LIBEV 3.X TO 4.X" |
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|
5198 | The major version 4 introduced some incompatible changes to the \s-1API\s0. |
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|
5199 | .PP |
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|
5200 | At the moment, the \f(CW\*(C`ev.h\*(C'\fR header file provides compatibility definitions |
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5201 | for all changes, so most programs should still compile. The compatibility |
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5202 | layer might be removed in later versions of libev, so better update to the |
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|
5203 | new \s-1API\s0 early than late. |
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|
5204 | .ie n .IP """EV_COMPAT3"" backwards compatibility mechanism" 4 |
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|
5205 | .el .IP "\f(CWEV_COMPAT3\fR backwards compatibility mechanism" 4 |
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|
5206 | .IX Item "EV_COMPAT3 backwards compatibility mechanism" |
|
|
5207 | The backward compatibility mechanism can be controlled by |
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|
5208 | \&\f(CW\*(C`EV_COMPAT3\*(C'\fR. See \*(L"\s-1MACROS\s0\*(R" in \s-1PREPROCESSOR\s0 \s-1SYMBOLS\s0 in the \s-1EMBEDDING\s0 |
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|
5209 | section. |
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|
5210 | .ie n .IP """ev_default_destroy"" and ""ev_default_fork"" have been removed" 4 |
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5211 | .el .IP "\f(CWev_default_destroy\fR and \f(CWev_default_fork\fR have been removed" 4 |
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5212 | .IX Item "ev_default_destroy and ev_default_fork have been removed" |
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5213 | These calls can be replaced easily by their \f(CW\*(C`ev_loop_xxx\*(C'\fR counterparts: |
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|
5214 | .Sp |
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5215 | .Vb 2 |
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|
5216 | \& ev_loop_destroy (EV_DEFAULT_UC); |
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5217 | \& ev_loop_fork (EV_DEFAULT); |
|
|
5218 | .Ve |
|
|
5219 | .IP "function/symbol renames" 4 |
|
|
5220 | .IX Item "function/symbol renames" |
|
|
5221 | A number of functions and symbols have been renamed: |
|
|
5222 | .Sp |
|
|
5223 | .Vb 3 |
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5224 | \& ev_loop => ev_run |
|
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5225 | \& EVLOOP_NONBLOCK => EVRUN_NOWAIT |
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5226 | \& EVLOOP_ONESHOT => EVRUN_ONCE |
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|
5227 | \& |
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|
5228 | \& ev_unloop => ev_break |
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5229 | \& EVUNLOOP_CANCEL => EVBREAK_CANCEL |
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5230 | \& EVUNLOOP_ONE => EVBREAK_ONE |
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|
5231 | \& EVUNLOOP_ALL => EVBREAK_ALL |
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|
5232 | \& |
|
|
5233 | \& EV_TIMEOUT => EV_TIMER |
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|
5234 | \& |
|
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5235 | \& ev_loop_count => ev_iteration |
|
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5236 | \& ev_loop_depth => ev_depth |
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|
5237 | \& ev_loop_verify => ev_verify |
|
|
5238 | .Ve |
|
|
5239 | .Sp |
|
|
5240 | Most functions working on \f(CW\*(C`struct ev_loop\*(C'\fR objects don't have an |
|
|
5241 | \&\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 |
|
|
5242 | associated constants have been renamed to not collide with the \f(CW\*(C`struct |
|
|
5243 | ev_loop\*(C'\fR anymore and \f(CW\*(C`EV_TIMER\*(C'\fR now follows the same naming scheme |
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5244 | as all other watcher types. Note that \f(CW\*(C`ev_loop_fork\*(C'\fR is still called |
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|
5245 | \&\f(CW\*(C`ev_loop_fork\*(C'\fR because it would otherwise clash with the \f(CW\*(C`ev_fork\*(C'\fR |
|
|
5246 | typedef. |
|
|
5247 | .ie n .IP """EV_MINIMAL"" mechanism replaced by ""EV_FEATURES""" 4 |
|
|
5248 | .el .IP "\f(CWEV_MINIMAL\fR mechanism replaced by \f(CWEV_FEATURES\fR" 4 |
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|
5249 | .IX Item "EV_MINIMAL mechanism replaced by EV_FEATURES" |
|
|
5250 | The preprocessor symbol \f(CW\*(C`EV_MINIMAL\*(C'\fR has been replaced by a different |
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5251 | mechanism, \f(CW\*(C`EV_FEATURES\*(C'\fR. Programs using \f(CW\*(C`EV_MINIMAL\*(C'\fR usually compile |
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5252 | and work, but the library code will of course be larger. |
|
|
5253 | .SH "GLOSSARY" |
|
|
5254 | .IX Header "GLOSSARY" |
|
|
5255 | .IP "active" 4 |
|
|
5256 | .IX Item "active" |
|
|
5257 | A watcher is active as long as it has been started and not yet stopped. |
|
|
5258 | See \*(L"\s-1WATCHER\s0 \s-1STATES\s0\*(R" for details. |
|
|
5259 | .IP "application" 4 |
|
|
5260 | .IX Item "application" |
|
|
5261 | In this document, an application is whatever is using libev. |
|
|
5262 | .IP "backend" 4 |
|
|
5263 | .IX Item "backend" |
|
|
5264 | The part of the code dealing with the operating system interfaces. |
|
|
5265 | .IP "callback" 4 |
|
|
5266 | .IX Item "callback" |
|
|
5267 | The address of a function that is called when some event has been |
|
|
5268 | detected. Callbacks are being passed the event loop, the watcher that |
|
|
5269 | received the event, and the actual event bitset. |
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5270 | .IP "callback/watcher invocation" 4 |
|
|
5271 | .IX Item "callback/watcher invocation" |
|
|
5272 | The act of calling the callback associated with a watcher. |
|
|
5273 | .IP "event" 4 |
|
|
5274 | .IX Item "event" |
|
|
5275 | A change of state of some external event, such as data now being available |
|
|
5276 | for reading on a file descriptor, time having passed or simply not having |
|
|
5277 | any other events happening anymore. |
|
|
5278 | .Sp |
|
|
5279 | In libev, events are represented as single bits (such as \f(CW\*(C`EV_READ\*(C'\fR or |
|
|
5280 | \&\f(CW\*(C`EV_TIMER\*(C'\fR). |
|
|
5281 | .IP "event library" 4 |
|
|
5282 | .IX Item "event library" |
|
|
5283 | A software package implementing an event model and loop. |
|
|
5284 | .IP "event loop" 4 |
|
|
5285 | .IX Item "event loop" |
|
|
5286 | An entity that handles and processes external events and converts them |
|
|
5287 | into callback invocations. |
|
|
5288 | .IP "event model" 4 |
|
|
5289 | .IX Item "event model" |
|
|
5290 | The model used to describe how an event loop handles and processes |
|
|
5291 | watchers and events. |
|
|
5292 | .IP "pending" 4 |
|
|
5293 | .IX Item "pending" |
|
|
5294 | A watcher is pending as soon as the corresponding event has been |
|
|
5295 | detected. See \*(L"\s-1WATCHER\s0 \s-1STATES\s0\*(R" for details. |
|
|
5296 | .IP "real time" 4 |
|
|
5297 | .IX Item "real time" |
|
|
5298 | The physical time that is observed. It is apparently strictly monotonic :) |
|
|
5299 | .IP "wall-clock time" 4 |
|
|
5300 | .IX Item "wall-clock time" |
|
|
5301 | The time and date as shown on clocks. Unlike real time, it can actually |
|
|
5302 | be wrong and jump forwards and backwards, e.g. when you adjust your |
|
|
5303 | clock. |
|
|
5304 | .IP "watcher" 4 |
|
|
5305 | .IX Item "watcher" |
|
|
5306 | A data structure that describes interest in certain events. Watchers need |
|
|
5307 | to be started (attached to an event loop) before they can receive events. |
3974 | .SH "AUTHOR" |
5308 | .SH "AUTHOR" |
3975 | .IX Header "AUTHOR" |
5309 | .IX Header "AUTHOR" |
3976 | Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael Magnusson. |
5310 | Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael |
|
|
5311 | Magnusson and Emanuele Giaquinta, and minor corrections by many others. |