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134 | .IX Title "LIBEV 3" |
126 | .IX Title "LIBEV 3" |
135 | .TH LIBEV 3 "2008-12-14" "libev-3.51" "libev - high performance full featured event loop" |
127 | .TH LIBEV 3 "2012-04-03" "libev-4.11" "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 | \& struct 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 <http://libev.schmorp.de/bench.html> 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_now_update\*(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 |
290 | either it is interrupted or the given time interval has passed. Basically |
303 | until either it is interrupted or the given time interval has |
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304 | passed (approximately \- it might return a bit earlier even if not |
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305 | interrupted). Returns immediately if \f(CW\*(C`interval <= 0\*(C'\fR. |
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306 | .Sp |
291 | this is a sub-second-resolution \f(CW\*(C`sleep ()\*(C'\fR. |
307 | Basically this is a sub-second-resolution \f(CW\*(C`sleep ()\*(C'\fR. |
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308 | .Sp |
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309 | The range of the \f(CW\*(C`interval\*(C'\fR is limited \- libev only guarantees to work |
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310 | with sleep times of up to one day (\f(CW\*(C`interval <= 86400\*(C'\fR). |
292 | .IP "int ev_version_major ()" 4 |
311 | .IP "int ev_version_major ()" 4 |
293 | .IX Item "int ev_version_major ()" |
312 | .IX Item "int ev_version_major ()" |
294 | .PD 0 |
313 | .PD 0 |
295 | .IP "int ev_version_minor ()" 4 |
314 | .IP "int ev_version_minor ()" 4 |
296 | .IX Item "int ev_version_minor ()" |
315 | .IX Item "int ev_version_minor ()" |
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308 | as this indicates an incompatible change. Minor versions are usually |
327 | as this indicates an incompatible change. Minor versions are usually |
309 | compatible to older versions, so a larger minor version alone is usually |
328 | compatible to older versions, so a larger minor version alone is usually |
310 | not a problem. |
329 | not a problem. |
311 | .Sp |
330 | .Sp |
312 | Example: Make sure we haven't accidentally been linked against the wrong |
331 | Example: Make sure we haven't accidentally been linked against the wrong |
313 | version. |
332 | version (note, however, that this will not detect other \s-1ABI\s0 mismatches, |
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333 | such as \s-1LFS\s0 or reentrancy). |
314 | .Sp |
334 | .Sp |
315 | .Vb 3 |
335 | .Vb 3 |
316 | \& assert (("libev version mismatch", |
336 | \& assert (("libev version mismatch", |
317 | \& ev_version_major () == EV_VERSION_MAJOR |
337 | \& ev_version_major () == EV_VERSION_MAJOR |
318 | \& && ev_version_minor () >= EV_VERSION_MINOR)); |
338 | \& && ev_version_minor () >= EV_VERSION_MINOR)); |
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331 | \& assert (("sorry, no epoll, no sex", |
351 | \& assert (("sorry, no epoll, no sex", |
332 | \& ev_supported_backends () & EVBACKEND_EPOLL)); |
352 | \& ev_supported_backends () & EVBACKEND_EPOLL)); |
333 | .Ve |
353 | .Ve |
334 | .IP "unsigned int ev_recommended_backends ()" 4 |
354 | .IP "unsigned int ev_recommended_backends ()" 4 |
335 | .IX Item "unsigned int ev_recommended_backends ()" |
355 | .IX Item "unsigned int ev_recommended_backends ()" |
336 | Return the set of all backends compiled into this binary of libev and also |
356 | 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 |
357 | also recommended for this platform, meaning it will work for most file |
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358 | 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 |
359 | \&\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 |
360 | 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 |
361 | 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. |
362 | probe for if you specify no backends explicitly. |
342 | .IP "unsigned int ev_embeddable_backends ()" 4 |
363 | .IP "unsigned int ev_embeddable_backends ()" 4 |
343 | .IX Item "unsigned int ev_embeddable_backends ()" |
364 | .IX Item "unsigned int ev_embeddable_backends ()" |
344 | Returns the set of backends that are embeddable in other event loops. This |
365 | Returns the set of backends that are embeddable in other event loops. This |
345 | is the theoretical, all-platform, value. To find which backends |
366 | 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 |
367 | 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 |
368 | the current system, you would need to look at \f(CW\*(C`ev_embeddable_backends () |
348 | recommended ones. |
369 | & ev_supported_backends ()\*(C'\fR, likewise for recommended ones. |
349 | .Sp |
370 | .Sp |
350 | See the description of \f(CW\*(C`ev_embed\*(C'\fR watchers for more info. |
371 | 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 |
372 | .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]" |
373 | .IX Item "ev_set_allocator (void *(*cb)(void *ptr, long size))" |
353 | Sets the allocation function to use (the prototype is similar \- the |
374 | 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 |
375 | 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 |
376 | 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 |
377 | when memory needs to be allocated (\f(CW\*(C`size != 0\*(C'\fR), the library might abort |
357 | or take some potentially destructive action. |
378 | or take some potentially destructive action. |
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383 | \& } |
404 | \& } |
384 | \& |
405 | \& |
385 | \& ... |
406 | \& ... |
386 | \& ev_set_allocator (persistent_realloc); |
407 | \& ev_set_allocator (persistent_realloc); |
387 | .Ve |
408 | .Ve |
388 | .IP "ev_set_syserr_cb (void (*cb)(const char *msg)); [\s-1NOT\s0 \s-1REENTRANT\s0]" 4 |
409 | .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]" |
410 | .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 |
411 | 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 |
412 | as failed select, poll, epoll_wait). The message is a printable string |
392 | indicating the system call or subsystem causing the problem. If this |
413 | 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 |
414 | 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 |
415 | matter what, when it returns. That is, libev will generally retry the |
… | |
… | |
406 | \& } |
427 | \& } |
407 | \& |
428 | \& |
408 | \& ... |
429 | \& ... |
409 | \& ev_set_syserr_cb (fatal_error); |
430 | \& ev_set_syserr_cb (fatal_error); |
410 | .Ve |
431 | .Ve |
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432 | .IP "ev_feed_signal (int signum)" 4 |
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433 | .IX Item "ev_feed_signal (int signum)" |
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434 | This function can be used to \*(L"simulate\*(R" a signal receive. It is completely |
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435 | safe to call this function at any time, from any context, including signal |
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436 | handlers or random threads. |
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437 | .Sp |
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438 | Its main use is to customise signal handling in your process, especially |
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439 | in the presence of threads. For example, you could block signals |
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440 | by default in all threads (and specifying \f(CW\*(C`EVFLAG_NOSIGMASK\*(C'\fR when |
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441 | creating any loops), and in one thread, use \f(CW\*(C`sigwait\*(C'\fR or any other |
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442 | mechanism to wait for signals, then \*(L"deliver\*(R" them to libev by calling |
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443 | \&\f(CW\*(C`ev_feed_signal\*(C'\fR. |
411 | .SH "FUNCTIONS CONTROLLING THE EVENT LOOP" |
444 | .SH "FUNCTIONS CONTROLLING EVENT LOOPS" |
412 | .IX Header "FUNCTIONS CONTROLLING THE EVENT LOOP" |
445 | .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 |
446 | 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 |
447 | \&\fInot\fR optional in this case unless libev 3 compatibility is disabled, as |
415 | \&\fIfunction\fR). |
448 | libev 3 had an \f(CW\*(C`ev_loop\*(C'\fR function colliding with the struct name). |
416 | .PP |
449 | .PP |
417 | The library knows two types of such loops, the \fIdefault\fR loop, which |
450 | 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 |
451 | supports child process events, and dynamically created event loops which |
419 | not. |
452 | do not. |
420 | .IP "struct ev_loop *ev_default_loop (unsigned int flags)" 4 |
453 | .IP "struct ev_loop *ev_default_loop (unsigned int flags)" 4 |
421 | .IX Item "struct ev_loop *ev_default_loop (unsigned int flags)" |
454 | .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 |
455 | 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 |
456 | 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 |
457 | 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). |
458 | \&\f(CW\*(C`ev_loop_new\*(C'\fR. |
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459 | .Sp |
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460 | If the default loop is already initialised then this function simply |
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461 | returns it (and ignores the flags. If that is troubling you, check |
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462 | \&\f(CW\*(C`ev_backend ()\*(C'\fR afterwards). Otherwise it will create it with the given |
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463 | flags, which should almost always be \f(CW0\fR, unless the caller is also the |
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464 | one calling \f(CW\*(C`ev_run\*(C'\fR or otherwise qualifies as \*(L"the main program\*(R". |
426 | .Sp |
465 | .Sp |
427 | If you don't know what event loop to use, use the one returned from this |
466 | If you don't know what event loop to use, use the one returned from this |
428 | function. |
467 | function (or via the \f(CW\*(C`EV_DEFAULT\*(C'\fR macro). |
429 | .Sp |
468 | .Sp |
430 | Note that this function is \fInot\fR thread-safe, so if you want to use it |
469 | 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, |
470 | from multiple threads, you have to employ some kind of mutex (note also |
432 | as loops cannot be shared easily between threads anyway). |
471 | that this case is unlikely, as loops cannot be shared easily between |
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472 | threads anyway). |
433 | .Sp |
473 | .Sp |
434 | The default loop is the only loop that can handle \f(CW\*(C`ev_signal\*(C'\fR and |
474 | 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 |
475 | 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 |
476 | 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 |
477 | \&\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 |
478 | \&\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. |
479 | .Sp |
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480 | Example: This is the most typical usage. |
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481 | .Sp |
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482 | .Vb 2 |
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|
483 | \& if (!ev_default_loop (0)) |
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484 | \& fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?"); |
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485 | .Ve |
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486 | .Sp |
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487 | Example: Restrict libev to the select and poll backends, and do not allow |
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488 | environment settings to be taken into account: |
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489 | .Sp |
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490 | .Vb 1 |
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491 | \& ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV); |
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492 | .Ve |
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493 | .IP "struct ev_loop *ev_loop_new (unsigned int flags)" 4 |
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|
494 | .IX Item "struct ev_loop *ev_loop_new (unsigned int flags)" |
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495 | This will create and initialise a new event loop object. If the loop |
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496 | could not be initialised, returns false. |
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497 | .Sp |
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498 | This function is thread-safe, and one common way to use libev with |
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499 | threads is indeed to create one loop per thread, and using the default |
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500 | loop in the \*(L"main\*(R" or \*(L"initial\*(R" thread. |
440 | .Sp |
501 | .Sp |
441 | The flags argument can be used to specify special behaviour or specific |
502 | 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). |
503 | backends to use, and is usually specified as \f(CW0\fR (or \f(CW\*(C`EVFLAG_AUTO\*(C'\fR). |
443 | .Sp |
504 | .Sp |
444 | The following flags are supported: |
505 | The following flags are supported: |
… | |
… | |
458 | useful to try out specific backends to test their performance, or to work |
519 | useful to try out specific backends to test their performance, or to work |
459 | around bugs. |
520 | around bugs. |
460 | .ie n .IP """EVFLAG_FORKCHECK""" 4 |
521 | .ie n .IP """EVFLAG_FORKCHECK""" 4 |
461 | .el .IP "\f(CWEVFLAG_FORKCHECK\fR" 4 |
522 | .el .IP "\f(CWEVFLAG_FORKCHECK\fR" 4 |
462 | .IX Item "EVFLAG_FORKCHECK" |
523 | .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 |
524 | 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 |
525 | make libev check for a fork in each iteration by enabling this flag. |
465 | enabling this flag. |
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|
466 | .Sp |
526 | .Sp |
467 | This works by calling \f(CW\*(C`getpid ()\*(C'\fR on every iteration of the loop, |
527 | 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 |
528 | 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 |
529 | 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 |
530 | 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 |
535 | forget about forgetting to tell libev about forking) when you use this |
476 | flag. |
536 | flag. |
477 | .Sp |
537 | .Sp |
478 | This flag setting cannot be overridden or specified in the \f(CW\*(C`LIBEV_FLAGS\*(C'\fR |
538 | This flag setting cannot be overridden or specified in the \f(CW\*(C`LIBEV_FLAGS\*(C'\fR |
479 | environment variable. |
539 | environment variable. |
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|
540 | .ie n .IP """EVFLAG_NOINOTIFY""" 4 |
|
|
541 | .el .IP "\f(CWEVFLAG_NOINOTIFY\fR" 4 |
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|
542 | .IX Item "EVFLAG_NOINOTIFY" |
|
|
543 | When this flag is specified, then libev will not attempt to use the |
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|
544 | \&\fIinotify\fR \s-1API\s0 for its \f(CW\*(C`ev_stat\*(C'\fR watchers. Apart from debugging and |
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545 | testing, this flag can be useful to conserve inotify file descriptors, as |
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|
546 | otherwise each loop using \f(CW\*(C`ev_stat\*(C'\fR watchers consumes one inotify handle. |
|
|
547 | .ie n .IP """EVFLAG_SIGNALFD""" 4 |
|
|
548 | .el .IP "\f(CWEVFLAG_SIGNALFD\fR" 4 |
|
|
549 | .IX Item "EVFLAG_SIGNALFD" |
|
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550 | When this flag is specified, then libev will attempt to use the |
|
|
551 | \&\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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552 | delivers signals synchronously, which makes it both faster and might make |
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553 | it possible to get the queued signal data. It can also simplify signal |
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554 | handling with threads, as long as you properly block signals in your |
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555 | threads that are not interested in handling them. |
|
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556 | .Sp |
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557 | Signalfd will not be used by default as this changes your signal mask, and |
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558 | there are a lot of shoddy libraries and programs (glib's threadpool for |
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|
559 | example) that can't properly initialise their signal masks. |
|
|
560 | .ie n .IP """EVFLAG_NOSIGMASK""" 4 |
|
|
561 | .el .IP "\f(CWEVFLAG_NOSIGMASK\fR" 4 |
|
|
562 | .IX Item "EVFLAG_NOSIGMASK" |
|
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563 | When this flag is specified, then libev will avoid to modify the signal |
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564 | mask. Specifically, this means you have to make sure signals are unblocked |
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565 | when you want to receive them. |
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|
566 | .Sp |
|
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567 | This behaviour is useful when you want to do your own signal handling, or |
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568 | want to handle signals only in specific threads and want to avoid libev |
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569 | unblocking the signals. |
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570 | .Sp |
|
|
571 | It's also required by \s-1POSIX\s0 in a threaded program, as libev calls |
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572 | \&\f(CW\*(C`sigprocmask\*(C'\fR, whose behaviour is officially unspecified. |
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|
573 | .Sp |
|
|
574 | 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 |
575 | .ie n .IP """EVBACKEND_SELECT"" (value 1, portable select backend)" 4 |
481 | .el .IP "\f(CWEVBACKEND_SELECT\fR (value 1, portable select backend)" 4 |
576 | .el .IP "\f(CWEVBACKEND_SELECT\fR (value 1, portable select backend)" 4 |
482 | .IX Item "EVBACKEND_SELECT (value 1, portable select backend)" |
577 | .IX Item "EVBACKEND_SELECT (value 1, portable select backend)" |
483 | This is your standard \fIselect\fR\|(2) backend. Not \fIcompletely\fR standard, as |
578 | 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, |
579 | 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 |
604 | 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. |
605 | \&\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 |
606 | .ie n .IP """EVBACKEND_EPOLL"" (value 4, Linux)" 4 |
512 | .el .IP "\f(CWEVBACKEND_EPOLL\fR (value 4, Linux)" 4 |
607 | .el .IP "\f(CWEVBACKEND_EPOLL\fR (value 4, Linux)" 4 |
513 | .IX Item "EVBACKEND_EPOLL (value 4, Linux)" |
608 | .IX Item "EVBACKEND_EPOLL (value 4, Linux)" |
|
|
609 | Use the linux-specific \fIepoll\fR\|(7) interface (for both pre\- and post\-2.6.9 |
|
|
610 | kernels). |
|
|
611 | .Sp |
514 | For few fds, this backend is a bit little slower than poll and select, |
612 | For few fds, this backend is a bit little slower than poll and select, but |
515 | but it scales phenomenally better. While poll and select usually scale |
613 | it scales phenomenally better. While poll and select usually scale like |
516 | like O(total_fds) where n is the total number of fds (or the highest fd), |
614 | O(total_fds) where total_fds is the total number of fds (or the highest |
517 | epoll scales either O(1) or O(active_fds). |
615 | fd), epoll scales either O(1) or O(active_fds). |
518 | .Sp |
616 | .Sp |
519 | The epoll mechanism deserves honorable mention as the most misdesigned |
617 | The epoll mechanism deserves honorable mention as the most misdesigned |
520 | of the more advanced event mechanisms: mere annoyances include silently |
618 | of the more advanced event mechanisms: mere annoyances include silently |
521 | dropping file descriptors, requiring a system call per change per file |
619 | dropping file descriptors, requiring a system call per change per file |
522 | descriptor (and unnecessary guessing of parameters), problems with dup and |
620 | descriptor (and unnecessary guessing of parameters), problems with dup, |
|
|
621 | returning before the timeout value, resulting in additional iterations |
|
|
622 | (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 |
623 | 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 |
624 | 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 |
625 | set, which can take considerable time (one syscall per file descriptor) |
526 | hard to detect. |
626 | and is of course hard to detect. |
527 | .Sp |
627 | .Sp |
528 | Epoll is also notoriously buggy \- embedding epoll fds \fIshould\fR work, but |
628 | Epoll is also notoriously buggy \- embedding epoll fds \fIshould\fR work, |
529 | of course \fIdoesn't\fR, and epoll just loves to report events for totally |
629 | but of course \fIdoesn't\fR, and epoll just loves to report events for |
530 | \&\fIdifferent\fR file descriptors (even already closed ones, so one cannot |
630 | totally \fIdifferent\fR file descriptors (even already closed ones, so |
531 | even remove them from the set) than registered in the set (especially |
631 | one cannot even remove them from the set) than registered in the set |
532 | on \s-1SMP\s0 systems). Libev tries to counter these spurious notifications by |
632 | (especially on \s-1SMP\s0 systems). Libev tries to counter these spurious |
533 | employing an additional generation counter and comparing that against the |
633 | notifications by employing an additional generation counter and comparing |
534 | events to filter out spurious ones, recreating the set when required. |
634 | that against the events to filter out spurious ones, recreating the set |
|
|
635 | when required. Epoll also erroneously rounds down timeouts, but gives you |
|
|
636 | no way to know when and by how much, so sometimes you have to busy-wait |
|
|
637 | because epoll returns immediately despite a nonzero timeout. And last |
|
|
638 | not least, it also refuses to work with some file descriptors which work |
|
|
639 | perfectly fine with \f(CW\*(C`select\*(C'\fR (files, many character devices...). |
|
|
640 | .Sp |
|
|
641 | Epoll is truly the train wreck among event poll mechanisms, a frankenpoll, |
|
|
642 | cobbled together in a hurry, no thought to design or interaction with |
|
|
643 | others. Oh, the pain, will it ever stop... |
535 | .Sp |
644 | .Sp |
536 | While stopping, setting and starting an I/O watcher in the same iteration |
645 | 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 |
646 | 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 |
647 | 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 |
648 | \&\fIfile description\fR now), so its best to avoid that. Also, \f(CW\*(C`dup ()\*(C'\fR'ed |
… | |
… | |
576 | .Sp |
685 | .Sp |
577 | It scales in the same way as the epoll backend, but the interface to the |
686 | It scales in the same way as the epoll backend, but the interface to the |
578 | kernel is more efficient (which says nothing about its actual speed, of |
687 | kernel is more efficient (which says nothing about its actual speed, of |
579 | course). While stopping, setting and starting an I/O watcher does never |
688 | course). While stopping, setting and starting an I/O watcher does never |
580 | cause an extra system call as with \f(CW\*(C`EVBACKEND_EPOLL\*(C'\fR, it still adds up to |
689 | cause an extra system call as with \f(CW\*(C`EVBACKEND_EPOLL\*(C'\fR, it still adds up to |
581 | two event changes per incident. Support for \f(CW\*(C`fork ()\*(C'\fR is very bad (but |
690 | two event changes per incident. Support for \f(CW\*(C`fork ()\*(C'\fR is very bad (you |
582 | sane, unlike epoll) and it drops fds silently in similarly hard-to-detect |
691 | might have to leak fd's on fork, but it's more sane than epoll) and it |
583 | cases |
692 | drops fds silently in similarly hard-to-detect cases |
584 | .Sp |
693 | .Sp |
585 | This backend usually performs well under most conditions. |
694 | This backend usually performs well under most conditions. |
586 | .Sp |
695 | .Sp |
587 | While nominally embeddable in other event loops, this doesn't work |
696 | 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 |
697 | everywhere, so you might need to test for this. And since it is broken |
… | |
… | |
605 | .el .IP "\f(CWEVBACKEND_PORT\fR (value 32, Solaris 10)" 4 |
714 | .el .IP "\f(CWEVBACKEND_PORT\fR (value 32, Solaris 10)" 4 |
606 | .IX Item "EVBACKEND_PORT (value 32, Solaris 10)" |
715 | .IX Item "EVBACKEND_PORT (value 32, Solaris 10)" |
607 | This uses the Solaris 10 event port mechanism. As with everything on Solaris, |
716 | 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)). |
717 | it's really slow, but it still scales very well (O(active_fds)). |
609 | .Sp |
718 | .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 |
719 | 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 |
720 | 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 |
721 | 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. |
722 | might perform better. |
618 | .Sp |
723 | .Sp |
619 | On the positive side, with the exception of the spurious readiness |
724 | 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 |
725 | specification in all tests and is fully embeddable, which is a rare feat |
622 | OS-specific backends (I vastly prefer correctness over speed hacks). |
726 | among the OS-specific backends (I vastly prefer correctness over speed |
|
|
727 | hacks). |
|
|
728 | .Sp |
|
|
729 | On the negative side, the interface is \fIbizarre\fR \- so bizarre that |
|
|
730 | even sun itself gets it wrong in their code examples: The event polling |
|
|
731 | function sometimes returns events to the caller even though an error |
|
|
732 | occurred, but with no indication whether it has done so or not (yes, it's |
|
|
733 | even documented that way) \- deadly for edge-triggered interfaces where you |
|
|
734 | absolutely have to know whether an event occurred or not because you have |
|
|
735 | to re-arm the watcher. |
|
|
736 | .Sp |
|
|
737 | Fortunately libev seems to be able to work around these idiocies. |
623 | .Sp |
738 | .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 |
739 | 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. |
740 | \&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
626 | .ie n .IP """EVBACKEND_ALL""" 4 |
741 | .ie n .IP """EVBACKEND_ALL""" 4 |
627 | .el .IP "\f(CWEVBACKEND_ALL\fR" 4 |
742 | .el .IP "\f(CWEVBACKEND_ALL\fR" 4 |
628 | .IX Item "EVBACKEND_ALL" |
743 | .IX Item "EVBACKEND_ALL" |
629 | Try all backends (even potentially broken ones that wouldn't be tried |
744 | 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 |
745 | 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. |
746 | \&\f(CW\*(C`EVBACKEND_ALL & ~EVBACKEND_KQUEUE\*(C'\fR. |
632 | .Sp |
747 | .Sp |
633 | It is definitely not recommended to use this flag. |
748 | It is definitely not recommended to use this flag, use whatever |
|
|
749 | \&\f(CW\*(C`ev_recommended_backends ()\*(C'\fR returns, or simply do not specify a backend |
|
|
750 | at all. |
|
|
751 | .ie n .IP """EVBACKEND_MASK""" 4 |
|
|
752 | .el .IP "\f(CWEVBACKEND_MASK\fR" 4 |
|
|
753 | .IX Item "EVBACKEND_MASK" |
|
|
754 | Not a backend at all, but a mask to select all backend bits from a |
|
|
755 | \&\f(CW\*(C`flags\*(C'\fR value, in case you want to mask out any backends from a flags |
|
|
756 | value (e.g. when modifying the \f(CW\*(C`LIBEV_FLAGS\*(C'\fR environment variable). |
634 | .RE |
757 | .RE |
635 | .RS 4 |
758 | .RS 4 |
636 | .Sp |
759 | .Sp |
637 | If one or more of these are or'ed into the flags value, then only these |
760 | 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 |
761 | 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. |
762 | here). If none are specified, all backends in \f(CW\*(C`ev_recommended_backends |
640 | .Sp |
763 | ()\*(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 |
764 | .Sp |
675 | Example: Try to create a event loop that uses epoll and nothing else. |
765 | Example: Try to create a event loop that uses epoll and nothing else. |
676 | .Sp |
766 | .Sp |
677 | .Vb 3 |
767 | .Vb 3 |
678 | \& struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); |
768 | \& struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); |
679 | \& if (!epoller) |
769 | \& if (!epoller) |
680 | \& fatal ("no epoll found here, maybe it hides under your chair"); |
770 | \& fatal ("no epoll found here, maybe it hides under your chair"); |
681 | .Ve |
771 | .Ve |
|
|
772 | .Sp |
|
|
773 | Example: Use whatever libev has to offer, but make sure that kqueue is |
|
|
774 | used if available. |
|
|
775 | .Sp |
|
|
776 | .Vb 1 |
|
|
777 | \& struct ev_loop *loop = ev_loop_new (ev_recommended_backends () | EVBACKEND_KQUEUE); |
|
|
778 | .Ve |
|
|
779 | .RE |
682 | .IP "ev_default_destroy ()" 4 |
780 | .IP "ev_loop_destroy (loop)" 4 |
683 | .IX Item "ev_default_destroy ()" |
781 | .IX Item "ev_loop_destroy (loop)" |
684 | Destroys the default loop again (frees all memory and kernel state |
782 | 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 |
783 | 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 |
784 | 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 |
785 | responsibility to either stop all watchers cleanly yourself \fIbefore\fR |
688 | calling this function, or cope with the fact afterwards (which is usually |
786 | 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 |
787 | the easiest thing, you can just ignore the watchers and/or \f(CW\*(C`free ()\*(C'\fR them |
… | |
… | |
691 | .Sp |
789 | .Sp |
692 | Note that certain global state, such as signal state (and installed signal |
790 | 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 |
791 | handlers), will not be freed by this function, and related watchers (such |
694 | as signal and child watchers) would need to be stopped manually. |
792 | as signal and child watchers) would need to be stopped manually. |
695 | .Sp |
793 | .Sp |
696 | In general it is not advisable to call this function except in the |
794 | This function is normally used on loop objects allocated by |
697 | rare occasion where you really need to free e.g. the signal handling |
795 | \&\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 |
796 | \&\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 |
797 | .Sp |
713 | On the other hand, you only need to call this function in the child |
798 | 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 |
799 | 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. |
800 | If you need dynamically allocated loops it is better to use \f(CW\*(C`ev_loop_new\*(C'\fR |
716 | .Sp |
801 | 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 |
802 | .IP "ev_loop_fork (loop)" 4 |
725 | .IX Item "ev_loop_fork (loop)" |
803 | .IX Item "ev_loop_fork (loop)" |
726 | Like \f(CW\*(C`ev_default_fork\*(C'\fR, but acts on an event loop created by |
804 | 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 |
805 | 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 |
806 | name, you can call it anytime, but it makes most sense after forking, in |
729 | entirely your own problem. |
807 | the child process. You \fImust\fR call it (or use \f(CW\*(C`EVFLAG_FORKCHECK\*(C'\fR) in the |
|
|
808 | child before resuming or calling \f(CW\*(C`ev_run\*(C'\fR. |
|
|
809 | .Sp |
|
|
810 | Again, you \fIhave\fR to call it on \fIany\fR loop that you want to re-use after |
|
|
811 | a fork, \fIeven if you do not plan to use the loop in the parent\fR. This is |
|
|
812 | because some kernel interfaces *cough* \fIkqueue\fR *cough* do funny things |
|
|
813 | during fork. |
|
|
814 | .Sp |
|
|
815 | On the other hand, you only need to call this function in the child |
|
|
816 | process if and only if you want to use the event loop in the child. If |
|
|
817 | you just fork+exec or create a new loop in the child, you don't have to |
|
|
818 | call it at all (in fact, \f(CW\*(C`epoll\*(C'\fR is so badly broken that it makes a |
|
|
819 | difference, but libev will usually detect this case on its own and do a |
|
|
820 | costly reset of the backend). |
|
|
821 | .Sp |
|
|
822 | The function itself is quite fast and it's usually not a problem to call |
|
|
823 | it just in case after a fork. |
|
|
824 | .Sp |
|
|
825 | Example: Automate calling \f(CW\*(C`ev_loop_fork\*(C'\fR on the default loop when |
|
|
826 | using pthreads. |
|
|
827 | .Sp |
|
|
828 | .Vb 5 |
|
|
829 | \& static void |
|
|
830 | \& post_fork_child (void) |
|
|
831 | \& { |
|
|
832 | \& ev_loop_fork (EV_DEFAULT); |
|
|
833 | \& } |
|
|
834 | \& |
|
|
835 | \& ... |
|
|
836 | \& pthread_atfork (0, 0, post_fork_child); |
|
|
837 | .Ve |
730 | .IP "int ev_is_default_loop (loop)" 4 |
838 | .IP "int ev_is_default_loop (loop)" 4 |
731 | .IX Item "int ev_is_default_loop (loop)" |
839 | .IX Item "int ev_is_default_loop (loop)" |
732 | Returns true when the given loop is, in fact, the default loop, and false |
840 | Returns true when the given loop is, in fact, the default loop, and false |
733 | otherwise. |
841 | otherwise. |
734 | .IP "unsigned int ev_loop_count (loop)" 4 |
842 | .IP "unsigned int ev_iteration (loop)" 4 |
735 | .IX Item "unsigned int ev_loop_count (loop)" |
843 | .IX Item "unsigned int ev_iteration (loop)" |
736 | Returns the count of loop iterations for the loop, which is identical to |
844 | 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 |
845 | to the number of times libev did poll for new events. It starts at \f(CW0\fR |
738 | happily wraps around with enough iterations. |
846 | and happily wraps around with enough iterations. |
739 | .Sp |
847 | .Sp |
740 | This value can sometimes be useful as a generation counter of sorts (it |
848 | 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 |
849 | \&\*(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. |
850 | \&\f(CW\*(C`ev_prepare\*(C'\fR and \f(CW\*(C`ev_check\*(C'\fR calls \- and is incremented between the |
|
|
851 | prepare and check phases. |
|
|
852 | .IP "unsigned int ev_depth (loop)" 4 |
|
|
853 | .IX Item "unsigned int ev_depth (loop)" |
|
|
854 | Returns the number of times \f(CW\*(C`ev_run\*(C'\fR was entered minus the number of |
|
|
855 | times \f(CW\*(C`ev_run\*(C'\fR was exited normally, in other words, the recursion depth. |
|
|
856 | .Sp |
|
|
857 | Outside \f(CW\*(C`ev_run\*(C'\fR, this number is zero. In a callback, this number is |
|
|
858 | \&\f(CW1\fR, unless \f(CW\*(C`ev_run\*(C'\fR was invoked recursively (or from another thread), |
|
|
859 | in which case it is higher. |
|
|
860 | .Sp |
|
|
861 | Leaving \f(CW\*(C`ev_run\*(C'\fR abnormally (setjmp/longjmp, cancelling the thread, |
|
|
862 | throwing an exception etc.), doesn't count as \*(L"exit\*(R" \- consider this |
|
|
863 | as a hint to avoid such ungentleman-like behaviour unless it's really |
|
|
864 | convenient, in which case it is fully supported. |
743 | .IP "unsigned int ev_backend (loop)" 4 |
865 | .IP "unsigned int ev_backend (loop)" 4 |
744 | .IX Item "unsigned int ev_backend (loop)" |
866 | .IX Item "unsigned int ev_backend (loop)" |
745 | Returns one of the \f(CW\*(C`EVBACKEND_*\*(C'\fR flags indicating the event backend in |
867 | Returns one of the \f(CW\*(C`EVBACKEND_*\*(C'\fR flags indicating the event backend in |
746 | use. |
868 | use. |
747 | .IP "ev_tstamp ev_now (loop)" 4 |
869 | .IP "ev_tstamp ev_now (loop)" 4 |
… | |
… | |
753 | event occurring (or more correctly, libev finding out about it). |
875 | event occurring (or more correctly, libev finding out about it). |
754 | .IP "ev_now_update (loop)" 4 |
876 | .IP "ev_now_update (loop)" 4 |
755 | .IX Item "ev_now_update (loop)" |
877 | .IX Item "ev_now_update (loop)" |
756 | Establishes the current time by querying the kernel, updating the time |
878 | 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 |
879 | 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. |
880 | is usually done automatically within \f(CW\*(C`ev_run ()\*(C'\fR. |
759 | .Sp |
881 | .Sp |
760 | This function is rarely useful, but when some event callback runs for a |
882 | 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 |
883 | very long time without entering the event loop, updating libev's idea of |
762 | the current time is a good idea. |
884 | the current time is a good idea. |
763 | .Sp |
885 | .Sp |
764 | See also \*(L"The special problem of time updates\*(R" in the \f(CW\*(C`ev_timer\*(C'\fR section. |
886 | See also \*(L"The special problem of time updates\*(R" in the \f(CW\*(C`ev_timer\*(C'\fR section. |
|
|
887 | .IP "ev_suspend (loop)" 4 |
|
|
888 | .IX Item "ev_suspend (loop)" |
|
|
889 | .PD 0 |
|
|
890 | .IP "ev_resume (loop)" 4 |
|
|
891 | .IX Item "ev_resume (loop)" |
|
|
892 | .PD |
|
|
893 | These two functions suspend and resume an event loop, for use when the |
|
|
894 | loop is not used for a while and timeouts should not be processed. |
|
|
895 | .Sp |
|
|
896 | A typical use case would be an interactive program such as a game: When |
|
|
897 | the user presses \f(CW\*(C`^Z\*(C'\fR to suspend the game and resumes it an hour later it |
|
|
898 | would be best to handle timeouts as if no time had actually passed while |
|
|
899 | the program was suspended. This can be achieved by calling \f(CW\*(C`ev_suspend\*(C'\fR |
|
|
900 | in your \f(CW\*(C`SIGTSTP\*(C'\fR handler, sending yourself a \f(CW\*(C`SIGSTOP\*(C'\fR and calling |
|
|
901 | \&\f(CW\*(C`ev_resume\*(C'\fR directly afterwards to resume timer processing. |
|
|
902 | .Sp |
|
|
903 | Effectively, all \f(CW\*(C`ev_timer\*(C'\fR watchers will be delayed by the time spend |
|
|
904 | 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 |
|
|
905 | will be rescheduled (that is, they will lose any events that would have |
|
|
906 | occurred while suspended). |
|
|
907 | .Sp |
|
|
908 | After calling \f(CW\*(C`ev_suspend\*(C'\fR you \fBmust not\fR call \fIany\fR function on the |
|
|
909 | given loop other than \f(CW\*(C`ev_resume\*(C'\fR, and you \fBmust not\fR call \f(CW\*(C`ev_resume\*(C'\fR |
|
|
910 | without a previous call to \f(CW\*(C`ev_suspend\*(C'\fR. |
|
|
911 | .Sp |
|
|
912 | Calling \f(CW\*(C`ev_suspend\*(C'\fR/\f(CW\*(C`ev_resume\*(C'\fR has the side effect of updating the |
|
|
913 | event loop time (see \f(CW\*(C`ev_now_update\*(C'\fR). |
765 | .IP "ev_loop (loop, int flags)" 4 |
914 | .IP "bool ev_run (loop, int flags)" 4 |
766 | .IX Item "ev_loop (loop, int flags)" |
915 | .IX Item "bool ev_run (loop, int flags)" |
767 | Finally, this is it, the event handler. This function usually is called |
916 | 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 |
917 | after you have initialised all your watchers and you want to start |
769 | events. |
918 | handling events. It will ask the operating system for any new events, call |
|
|
919 | the watcher callbacks, and then repeat the whole process indefinitely: This |
|
|
920 | is why event loops are called \fIloops\fR. |
770 | .Sp |
921 | .Sp |
771 | If the flags argument is specified as \f(CW0\fR, it will not return until |
922 | 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. |
923 | until either no event watchers are active anymore or \f(CW\*(C`ev_break\*(C'\fR was |
|
|
924 | called. |
773 | .Sp |
925 | .Sp |
|
|
926 | The return value is false if there are no more active watchers (which |
|
|
927 | usually means \*(L"all jobs done\*(R" or \*(L"deadlock\*(R"), and true in all other cases |
|
|
928 | (which usually means " you should call \f(CW\*(C`ev_run\*(C'\fR again"). |
|
|
929 | .Sp |
774 | Please note that an explicit \f(CW\*(C`ev_unloop\*(C'\fR is usually better than |
930 | 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 |
931 | relying on all watchers to be stopped when deciding when a program has |
776 | finished (especially in interactive programs), but having a program |
932 | finished (especially in interactive programs), but having a program |
777 | that automatically loops as long as it has to and no longer by virtue |
933 | 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 |
934 | of relying on its watchers stopping correctly, that is truly a thing of |
779 | beauty. |
935 | beauty. |
780 | .Sp |
936 | .Sp |
|
|
937 | This function is \fImostly\fR exception-safe \- you can break out of a |
|
|
938 | \&\f(CW\*(C`ev_run\*(C'\fR call by calling \f(CW\*(C`longjmp\*(C'\fR in a callback, throwing a \*(C+ |
|
|
939 | exception and so on. This does not decrement the \f(CW\*(C`ev_depth\*(C'\fR value, nor |
|
|
940 | will it clear any outstanding \f(CW\*(C`EVBREAK_ONE\*(C'\fR breaks. |
|
|
941 | .Sp |
781 | A flags value of \f(CW\*(C`EVLOOP_NONBLOCK\*(C'\fR will look for new events, will handle |
942 | 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 |
943 | 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 |
944 | block your process in case there are no events and will return after one |
784 | the loop. |
945 | iteration of the loop. This is sometimes useful to poll and handle new |
|
|
946 | events while doing lengthy calculations, to keep the program responsive. |
785 | .Sp |
947 | .Sp |
786 | A flags value of \f(CW\*(C`EVLOOP_ONESHOT\*(C'\fR will look for new events (waiting if |
948 | 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 |
949 | 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 |
950 | 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 |
951 | 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 |
952 | user-registered callback will be called), and will return after one |
791 | iteration of the loop. |
953 | iteration of the loop. |
792 | .Sp |
954 | .Sp |
793 | This is useful if you are waiting for some external event in conjunction |
955 | 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 |
956 | 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 |
957 | 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. |
958 | usually a better approach for this kind of thing. |
797 | .Sp |
959 | .Sp |
798 | Here are the gory details of what \f(CW\*(C`ev_loop\*(C'\fR does: |
960 | Here are the gory details of what \f(CW\*(C`ev_run\*(C'\fR does (this is for your |
|
|
961 | understanding, not a guarantee that things will work exactly like this in |
|
|
962 | future versions): |
799 | .Sp |
963 | .Sp |
800 | .Vb 10 |
964 | .Vb 10 |
|
|
965 | \& \- Increment loop depth. |
|
|
966 | \& \- Reset the ev_break status. |
801 | \& \- Before the first iteration, call any pending watchers. |
967 | \& \- Before the first iteration, call any pending watchers. |
|
|
968 | \& LOOP: |
802 | \& * If EVFLAG_FORKCHECK was used, check for a fork. |
969 | \& \- If EVFLAG_FORKCHECK was used, check for a fork. |
803 | \& \- If a fork was detected (by any means), queue and call all fork watchers. |
970 | \& \- If a fork was detected (by any means), queue and call all fork watchers. |
804 | \& \- Queue and call all prepare watchers. |
971 | \& \- Queue and call all prepare watchers. |
|
|
972 | \& \- If ev_break was called, goto FINISH. |
805 | \& \- If we have been forked, detach and recreate the kernel state |
973 | \& \- If we have been forked, detach and recreate the kernel state |
806 | \& as to not disturb the other process. |
974 | \& as to not disturb the other process. |
807 | \& \- Update the kernel state with all outstanding changes. |
975 | \& \- Update the kernel state with all outstanding changes. |
808 | \& \- Update the "event loop time" (ev_now ()). |
976 | \& \- Update the "event loop time" (ev_now ()). |
809 | \& \- Calculate for how long to sleep or block, if at all |
977 | \& \- Calculate for how long to sleep or block, if at all |
810 | \& (active idle watchers, EVLOOP_NONBLOCK or not having |
978 | \& (active idle watchers, EVRUN_NOWAIT or not having |
811 | \& any active watchers at all will result in not sleeping). |
979 | \& any active watchers at all will result in not sleeping). |
812 | \& \- Sleep if the I/O and timer collect interval say so. |
980 | \& \- Sleep if the I/O and timer collect interval say so. |
|
|
981 | \& \- Increment loop iteration counter. |
813 | \& \- Block the process, waiting for any events. |
982 | \& \- Block the process, waiting for any events. |
814 | \& \- Queue all outstanding I/O (fd) events. |
983 | \& \- Queue all outstanding I/O (fd) events. |
815 | \& \- Update the "event loop time" (ev_now ()), and do time jump adjustments. |
984 | \& \- Update the "event loop time" (ev_now ()), and do time jump adjustments. |
816 | \& \- Queue all expired timers. |
985 | \& \- Queue all expired timers. |
817 | \& \- Queue all expired periodics. |
986 | \& \- Queue all expired periodics. |
818 | \& \- Unless any events are pending now, queue all idle watchers. |
987 | \& \- Queue all idle watchers with priority higher than that of pending events. |
819 | \& \- Queue all check watchers. |
988 | \& \- Queue all check watchers. |
820 | \& \- Call all queued watchers in reverse order (i.e. check watchers first). |
989 | \& \- 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 |
990 | \& Signals and child watchers are implemented as I/O watchers, and will |
822 | \& be handled here by queueing them when their watcher gets executed. |
991 | \& be handled here by queueing them when their watcher gets executed. |
823 | \& \- If ev_unloop has been called, or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
992 | \& \- If ev_break has been called, or EVRUN_ONCE or EVRUN_NOWAIT |
824 | \& were used, or there are no active watchers, return, otherwise |
993 | \& were used, or there are no active watchers, goto FINISH, otherwise |
825 | \& continue with step *. |
994 | \& continue with step LOOP. |
|
|
995 | \& FINISH: |
|
|
996 | \& \- Reset the ev_break status iff it was EVBREAK_ONE. |
|
|
997 | \& \- Decrement the loop depth. |
|
|
998 | \& \- Return. |
826 | .Ve |
999 | .Ve |
827 | .Sp |
1000 | .Sp |
828 | Example: Queue some jobs and then loop until no events are outstanding |
1001 | Example: Queue some jobs and then loop until no events are outstanding |
829 | anymore. |
1002 | anymore. |
830 | .Sp |
1003 | .Sp |
831 | .Vb 4 |
1004 | .Vb 4 |
832 | \& ... queue jobs here, make sure they register event watchers as long |
1005 | \& ... 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..) |
1006 | \& ... as they still have work to do (even an idle watcher will do..) |
834 | \& ev_loop (my_loop, 0); |
1007 | \& ev_run (my_loop, 0); |
835 | \& ... jobs done or somebody called unloop. yeah! |
1008 | \& ... jobs done or somebody called break. yeah! |
836 | .Ve |
1009 | .Ve |
837 | .IP "ev_unloop (loop, how)" 4 |
1010 | .IP "ev_break (loop, how)" 4 |
838 | .IX Item "ev_unloop (loop, how)" |
1011 | .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 |
1012 | 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 |
1013 | 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 |
1014 | \&\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. |
1015 | \&\f(CW\*(C`EVBREAK_ALL\*(C'\fR, which will make all nested \f(CW\*(C`ev_run\*(C'\fR calls return. |
843 | .Sp |
1016 | .Sp |
844 | This \*(L"unloop state\*(R" will be cleared when entering \f(CW\*(C`ev_loop\*(C'\fR again. |
1017 | This \*(L"break state\*(R" will be cleared on the next call to \f(CW\*(C`ev_run\*(C'\fR. |
845 | .Sp |
1018 | .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. |
1019 | 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 |
|
|
1020 | which case it will have no effect. |
847 | .IP "ev_ref (loop)" 4 |
1021 | .IP "ev_ref (loop)" 4 |
848 | .IX Item "ev_ref (loop)" |
1022 | .IX Item "ev_ref (loop)" |
849 | .PD 0 |
1023 | .PD 0 |
850 | .IP "ev_unref (loop)" 4 |
1024 | .IP "ev_unref (loop)" 4 |
851 | .IX Item "ev_unref (loop)" |
1025 | .IX Item "ev_unref (loop)" |
852 | .PD |
1026 | .PD |
853 | Ref/unref can be used to add or remove a reference count on the event |
1027 | 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 |
1028 | 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. |
1029 | count is nonzero, \f(CW\*(C`ev_run\*(C'\fR will not return on its own. |
856 | .Sp |
1030 | .Sp |
857 | If you have a watcher you never unregister that should not keep \f(CW\*(C`ev_loop\*(C'\fR |
1031 | 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 |
1032 | unregister, but that nevertheless should not keep \f(CW\*(C`ev_run\*(C'\fR from |
|
|
1033 | 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. |
1034 | before stopping it. |
860 | .Sp |
1035 | .Sp |
861 | As an example, libev itself uses this for its internal signal pipe: It is |
1036 | 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 |
1037 | 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 |
1038 | 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 |
1039 | 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 |
1040 | 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, |
1041 | before stop\fR (but only if the watcher wasn't active before, or was active |
867 | respectively). |
1042 | before, respectively. Note also that libev might stop watchers itself |
|
|
1043 | (e.g. non-repeating timers) in which case you have to \f(CW\*(C`ev_ref\*(C'\fR |
|
|
1044 | in the callback). |
868 | .Sp |
1045 | .Sp |
869 | Example: Create a signal watcher, but keep it from keeping \f(CW\*(C`ev_loop\*(C'\fR |
1046 | Example: Create a signal watcher, but keep it from keeping \f(CW\*(C`ev_run\*(C'\fR |
870 | running when nothing else is active. |
1047 | running when nothing else is active. |
871 | .Sp |
1048 | .Sp |
872 | .Vb 4 |
1049 | .Vb 4 |
873 | \& ev_signal exitsig; |
1050 | \& ev_signal exitsig; |
874 | \& ev_signal_init (&exitsig, sig_cb, SIGINT); |
1051 | \& ev_signal_init (&exitsig, sig_cb, SIGINT); |
875 | \& ev_signal_start (loop, &exitsig); |
1052 | \& ev_signal_start (loop, &exitsig); |
876 | \& evf_unref (loop); |
1053 | \& ev_unref (loop); |
877 | .Ve |
1054 | .Ve |
878 | .Sp |
1055 | .Sp |
879 | Example: For some weird reason, unregister the above signal handler again. |
1056 | Example: For some weird reason, unregister the above signal handler again. |
880 | .Sp |
1057 | .Sp |
881 | .Vb 2 |
1058 | .Vb 2 |
… | |
… | |
905 | overhead for the actual polling but can deliver many events at once. |
1082 | overhead for the actual polling but can deliver many events at once. |
906 | .Sp |
1083 | .Sp |
907 | By setting a higher \fIio collect interval\fR you allow libev to spend more |
1084 | 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, |
1085 | 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 |
1086 | 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 |
1087 | \&\f(CW\*(C`ev_timer\*(C'\fR) will not be 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. |
1088 | introduce an additional \f(CW\*(C`ev_sleep ()\*(C'\fR call into most loop iterations. The |
|
|
1089 | sleep time ensures that libev will not poll for I/O events more often then |
|
|
1090 | once per this interval, on average (as long as the host time resolution is |
|
|
1091 | good enough). |
912 | .Sp |
1092 | .Sp |
913 | Likewise, by setting a higher \fItimeout collect interval\fR you allow libev |
1093 | Likewise, by setting a higher \fItimeout collect interval\fR you allow libev |
914 | to spend more time collecting timeouts, at the expense of increased |
1094 | to spend more time collecting timeouts, at the expense of increased |
915 | latency/jitter/inexactness (the watcher callback will be called |
1095 | 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 |
1096 | later). \f(CW\*(C`ev_io\*(C'\fR watchers will not be affected. Setting this to a non-null |
… | |
… | |
918 | .Sp |
1098 | .Sp |
919 | Many (busy) programs can usually benefit by setting the I/O collect |
1099 | 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 |
1100 | 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 |
1101 | 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, |
1102 | 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. |
1103 | as this approaches the timing granularity of most systems. Note that if |
|
|
1104 | you do transactions with the outside world and you can't increase the |
|
|
1105 | parallelity, then this setting will limit your transaction rate (if you |
|
|
1106 | need to poll once per transaction and the I/O collect interval is 0.01, |
|
|
1107 | then you can't do more than 100 transactions per second). |
924 | .Sp |
1108 | .Sp |
925 | Setting the \fItimeout collect interval\fR can improve the opportunity for |
1109 | 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 |
1110 | 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 |
1111 | 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 |
1112 | 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 |
1113 | 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. |
1114 | they fire on, say, one-second boundaries only. |
|
|
1115 | .Sp |
|
|
1116 | Example: we only need 0.1s timeout granularity, and we wish not to poll |
|
|
1117 | more often than 100 times per second: |
|
|
1118 | .Sp |
|
|
1119 | .Vb 2 |
|
|
1120 | \& ev_set_timeout_collect_interval (EV_DEFAULT_UC_ 0.1); |
|
|
1121 | \& ev_set_io_collect_interval (EV_DEFAULT_UC_ 0.01); |
|
|
1122 | .Ve |
|
|
1123 | .IP "ev_invoke_pending (loop)" 4 |
|
|
1124 | .IX Item "ev_invoke_pending (loop)" |
|
|
1125 | This call will simply invoke all pending watchers while resetting their |
|
|
1126 | pending state. Normally, \f(CW\*(C`ev_run\*(C'\fR does this automatically when required, |
|
|
1127 | but when overriding the invoke callback this call comes handy. This |
|
|
1128 | function can be invoked from a watcher \- this can be useful for example |
|
|
1129 | when you want to do some lengthy calculation and want to pass further |
|
|
1130 | event handling to another thread (you still have to make sure only one |
|
|
1131 | thread executes within \f(CW\*(C`ev_invoke_pending\*(C'\fR or \f(CW\*(C`ev_run\*(C'\fR of course). |
|
|
1132 | .IP "int ev_pending_count (loop)" 4 |
|
|
1133 | .IX Item "int ev_pending_count (loop)" |
|
|
1134 | Returns the number of pending watchers \- zero indicates that no watchers |
|
|
1135 | are pending. |
|
|
1136 | .IP "ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(\s-1EV_P\s0))" 4 |
|
|
1137 | .IX Item "ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(EV_P))" |
|
|
1138 | This overrides the invoke pending functionality of the loop: Instead of |
|
|
1139 | invoking all pending watchers when there are any, \f(CW\*(C`ev_run\*(C'\fR will call |
|
|
1140 | this callback instead. This is useful, for example, when you want to |
|
|
1141 | invoke the actual watchers inside another context (another thread etc.). |
|
|
1142 | .Sp |
|
|
1143 | If you want to reset the callback, use \f(CW\*(C`ev_invoke_pending\*(C'\fR as new |
|
|
1144 | callback. |
|
|
1145 | .IP "ev_set_loop_release_cb (loop, void (*release)(\s-1EV_P\s0), void (*acquire)(\s-1EV_P\s0))" 4 |
|
|
1146 | .IX Item "ev_set_loop_release_cb (loop, void (*release)(EV_P), void (*acquire)(EV_P))" |
|
|
1147 | Sometimes you want to share the same loop between multiple threads. This |
|
|
1148 | can be done relatively simply by putting mutex_lock/unlock calls around |
|
|
1149 | each call to a libev function. |
|
|
1150 | .Sp |
|
|
1151 | However, \f(CW\*(C`ev_run\*(C'\fR can run an indefinite time, so it is not feasible |
|
|
1152 | to wait for it to return. One way around this is to wake up the event |
|
|
1153 | loop via \f(CW\*(C`ev_break\*(C'\fR and \f(CW\*(C`ev_async_send\*(C'\fR, another way is to set these |
|
|
1154 | \&\fIrelease\fR and \fIacquire\fR callbacks on the loop. |
|
|
1155 | .Sp |
|
|
1156 | When set, then \f(CW\*(C`release\*(C'\fR will be called just before the thread is |
|
|
1157 | suspended waiting for new events, and \f(CW\*(C`acquire\*(C'\fR is called just |
|
|
1158 | afterwards. |
|
|
1159 | .Sp |
|
|
1160 | Ideally, \f(CW\*(C`release\*(C'\fR will just call your mutex_unlock function, and |
|
|
1161 | \&\f(CW\*(C`acquire\*(C'\fR will just call the mutex_lock function again. |
|
|
1162 | .Sp |
|
|
1163 | While event loop modifications are allowed between invocations of |
|
|
1164 | \&\f(CW\*(C`release\*(C'\fR and \f(CW\*(C`acquire\*(C'\fR (that's their only purpose after all), no |
|
|
1165 | modifications done will affect the event loop, i.e. adding watchers will |
|
|
1166 | have no effect on the set of file descriptors being watched, or the time |
|
|
1167 | 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 |
|
|
1168 | to take note of any changes you made. |
|
|
1169 | .Sp |
|
|
1170 | In theory, threads executing \f(CW\*(C`ev_run\*(C'\fR will be async-cancel safe between |
|
|
1171 | invocations of \f(CW\*(C`release\*(C'\fR and \f(CW\*(C`acquire\*(C'\fR. |
|
|
1172 | .Sp |
|
|
1173 | See also the locking example in the \f(CW\*(C`THREADS\*(C'\fR section later in this |
|
|
1174 | document. |
|
|
1175 | .IP "ev_set_userdata (loop, void *data)" 4 |
|
|
1176 | .IX Item "ev_set_userdata (loop, void *data)" |
|
|
1177 | .PD 0 |
|
|
1178 | .IP "void *ev_userdata (loop)" 4 |
|
|
1179 | .IX Item "void *ev_userdata (loop)" |
|
|
1180 | .PD |
|
|
1181 | Set and retrieve a single \f(CW\*(C`void *\*(C'\fR associated with a loop. When |
|
|
1182 | \&\f(CW\*(C`ev_set_userdata\*(C'\fR has never been called, then \f(CW\*(C`ev_userdata\*(C'\fR returns |
|
|
1183 | \&\f(CW0\fR. |
|
|
1184 | .Sp |
|
|
1185 | These two functions can be used to associate arbitrary data with a loop, |
|
|
1186 | and are intended solely for the \f(CW\*(C`invoke_pending_cb\*(C'\fR, \f(CW\*(C`release\*(C'\fR and |
|
|
1187 | \&\f(CW\*(C`acquire\*(C'\fR callbacks described above, but of course can be (ab\-)used for |
|
|
1188 | any other purpose as well. |
931 | .IP "ev_loop_verify (loop)" 4 |
1189 | .IP "ev_verify (loop)" 4 |
932 | .IX Item "ev_loop_verify (loop)" |
1190 | .IX Item "ev_verify (loop)" |
933 | This function only does something when \f(CW\*(C`EV_VERIFY\*(C'\fR support has been |
1191 | 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 |
1192 | 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 |
1193 | 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 |
1194 | is found to be inconsistent, it will print an error message to standard |
937 | error and call \f(CW\*(C`abort ()\*(C'\fR. |
1195 | error and call \f(CW\*(C`abort ()\*(C'\fR. |
… | |
… | |
943 | .IX Header "ANATOMY OF A WATCHER" |
1201 | .IX Header "ANATOMY OF A WATCHER" |
944 | In the following description, uppercase \f(CW\*(C`TYPE\*(C'\fR in names stands for the |
1202 | 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 |
1203 | 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. |
1204 | watchers and \f(CW\*(C`ev_io_start\*(C'\fR for I/O watchers. |
947 | .PP |
1205 | .PP |
948 | A watcher is a structure that you create and register to record your |
1206 | 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 |
1207 | 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: |
1208 | to wait for \s-1STDIN\s0 to become readable, you would create an \f(CW\*(C`ev_io\*(C'\fR watcher |
|
|
1209 | for that: |
951 | .PP |
1210 | .PP |
952 | .Vb 5 |
1211 | .Vb 5 |
953 | \& static void my_cb (struct ev_loop *loop, ev_io *w, int revents) |
1212 | \& static void my_cb (struct ev_loop *loop, ev_io *w, int revents) |
954 | \& { |
1213 | \& { |
955 | \& ev_io_stop (w); |
1214 | \& ev_io_stop (w); |
956 | \& ev_unloop (loop, EVUNLOOP_ALL); |
1215 | \& ev_break (loop, EVBREAK_ALL); |
957 | \& } |
1216 | \& } |
958 | \& |
1217 | \& |
959 | \& struct ev_loop *loop = ev_default_loop (0); |
1218 | \& struct ev_loop *loop = ev_default_loop (0); |
960 | \& |
1219 | \& |
961 | \& ev_io stdin_watcher; |
1220 | \& ev_io stdin_watcher; |
962 | \& |
1221 | \& |
963 | \& ev_init (&stdin_watcher, my_cb); |
1222 | \& ev_init (&stdin_watcher, my_cb); |
964 | \& ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ); |
1223 | \& ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ); |
965 | \& ev_io_start (loop, &stdin_watcher); |
1224 | \& ev_io_start (loop, &stdin_watcher); |
966 | \& |
1225 | \& |
967 | \& ev_loop (loop, 0); |
1226 | \& ev_run (loop, 0); |
968 | .Ve |
1227 | .Ve |
969 | .PP |
1228 | .PP |
970 | As you can see, you are responsible for allocating the memory for your |
1229 | 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 |
1230 | watcher structures (and it is \fIusually\fR a bad idea to do this on the |
972 | stack). |
1231 | stack). |
973 | .PP |
1232 | .PP |
974 | Each watcher has an associated watcher structure (called \f(CW\*(C`struct ev_TYPE\*(C'\fR |
1233 | 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). |
1234 | or simply \f(CW\*(C`ev_TYPE\*(C'\fR, as typedefs are provided for all watcher structs). |
976 | .PP |
1235 | .PP |
977 | Each watcher structure must be initialised by a call to \f(CW\*(C`ev_init |
1236 | 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 |
1237 | *, 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 |
1238 | 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 |
1239 | time the event loop detects that the file descriptor given is readable |
981 | is readable and/or writable). |
1240 | and/or writable). |
982 | .PP |
1241 | .PP |
983 | Each watcher type further has its own \f(CW\*(C`ev_TYPE_set (watcher *, ...)\*(C'\fR |
1242 | 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 |
1243 | 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. |
1244 | is also a macro to combine initialisation and setting in one call: \f(CW\*(C`ev_TYPE_init (watcher *, callback, ...)\*(C'\fR. |
986 | .PP |
1245 | .PP |
… | |
… | |
1008 | .el .IP "\f(CWEV_WRITE\fR" 4 |
1267 | .el .IP "\f(CWEV_WRITE\fR" 4 |
1009 | .IX Item "EV_WRITE" |
1268 | .IX Item "EV_WRITE" |
1010 | .PD |
1269 | .PD |
1011 | The file descriptor in the \f(CW\*(C`ev_io\*(C'\fR watcher has become readable and/or |
1270 | The file descriptor in the \f(CW\*(C`ev_io\*(C'\fR watcher has become readable and/or |
1012 | writable. |
1271 | writable. |
1013 | .ie n .IP """EV_TIMEOUT""" 4 |
1272 | .ie n .IP """EV_TIMER""" 4 |
1014 | .el .IP "\f(CWEV_TIMEOUT\fR" 4 |
1273 | .el .IP "\f(CWEV_TIMER\fR" 4 |
1015 | .IX Item "EV_TIMEOUT" |
1274 | .IX Item "EV_TIMER" |
1016 | The \f(CW\*(C`ev_timer\*(C'\fR watcher has timed out. |
1275 | The \f(CW\*(C`ev_timer\*(C'\fR watcher has timed out. |
1017 | .ie n .IP """EV_PERIODIC""" 4 |
1276 | .ie n .IP """EV_PERIODIC""" 4 |
1018 | .el .IP "\f(CWEV_PERIODIC\fR" 4 |
1277 | .el .IP "\f(CWEV_PERIODIC\fR" 4 |
1019 | .IX Item "EV_PERIODIC" |
1278 | .IX Item "EV_PERIODIC" |
1020 | The \f(CW\*(C`ev_periodic\*(C'\fR watcher has timed out. |
1279 | The \f(CW\*(C`ev_periodic\*(C'\fR watcher has timed out. |
… | |
… | |
1040 | .PD 0 |
1299 | .PD 0 |
1041 | .ie n .IP """EV_CHECK""" 4 |
1300 | .ie n .IP """EV_CHECK""" 4 |
1042 | .el .IP "\f(CWEV_CHECK\fR" 4 |
1301 | .el .IP "\f(CWEV_CHECK\fR" 4 |
1043 | .IX Item "EV_CHECK" |
1302 | .IX Item "EV_CHECK" |
1044 | .PD |
1303 | .PD |
1045 | All \f(CW\*(C`ev_prepare\*(C'\fR watchers are invoked just \fIbefore\fR \f(CW\*(C`ev_loop\*(C'\fR starts |
1304 | 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 |
1305 | 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 |
1306 | \&\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 |
1307 | 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 |
1308 | 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 |
1309 | (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). |
1310 | \&\f(CW\*(C`ev_run\*(C'\fR from blocking). |
1052 | .ie n .IP """EV_EMBED""" 4 |
1311 | .ie n .IP """EV_EMBED""" 4 |
1053 | .el .IP "\f(CWEV_EMBED\fR" 4 |
1312 | .el .IP "\f(CWEV_EMBED\fR" 4 |
1054 | .IX Item "EV_EMBED" |
1313 | .IX Item "EV_EMBED" |
1055 | The embedded event loop specified in the \f(CW\*(C`ev_embed\*(C'\fR watcher needs attention. |
1314 | The embedded event loop specified in the \f(CW\*(C`ev_embed\*(C'\fR watcher needs attention. |
1056 | .ie n .IP """EV_FORK""" 4 |
1315 | .ie n .IP """EV_FORK""" 4 |
1057 | .el .IP "\f(CWEV_FORK\fR" 4 |
1316 | .el .IP "\f(CWEV_FORK\fR" 4 |
1058 | .IX Item "EV_FORK" |
1317 | .IX Item "EV_FORK" |
1059 | The event loop has been resumed in the child process after fork (see |
1318 | The event loop has been resumed in the child process after fork (see |
1060 | \&\f(CW\*(C`ev_fork\*(C'\fR). |
1319 | \&\f(CW\*(C`ev_fork\*(C'\fR). |
|
|
1320 | .ie n .IP """EV_CLEANUP""" 4 |
|
|
1321 | .el .IP "\f(CWEV_CLEANUP\fR" 4 |
|
|
1322 | .IX Item "EV_CLEANUP" |
|
|
1323 | The event loop is about to be destroyed (see \f(CW\*(C`ev_cleanup\*(C'\fR). |
1061 | .ie n .IP """EV_ASYNC""" 4 |
1324 | .ie n .IP """EV_ASYNC""" 4 |
1062 | .el .IP "\f(CWEV_ASYNC\fR" 4 |
1325 | .el .IP "\f(CWEV_ASYNC\fR" 4 |
1063 | .IX Item "EV_ASYNC" |
1326 | .IX Item "EV_ASYNC" |
1064 | The given async watcher has been asynchronously notified (see \f(CW\*(C`ev_async\*(C'\fR). |
1327 | The given async watcher has been asynchronously notified (see \f(CW\*(C`ev_async\*(C'\fR). |
|
|
1328 | .ie n .IP """EV_CUSTOM""" 4 |
|
|
1329 | .el .IP "\f(CWEV_CUSTOM\fR" 4 |
|
|
1330 | .IX Item "EV_CUSTOM" |
|
|
1331 | Not ever sent (or otherwise used) by libev itself, but can be freely used |
|
|
1332 | by libev users to signal watchers (e.g. via \f(CW\*(C`ev_feed_event\*(C'\fR). |
1065 | .ie n .IP """EV_ERROR""" 4 |
1333 | .ie n .IP """EV_ERROR""" 4 |
1066 | .el .IP "\f(CWEV_ERROR\fR" 4 |
1334 | .el .IP "\f(CWEV_ERROR\fR" 4 |
1067 | .IX Item "EV_ERROR" |
1335 | .IX Item "EV_ERROR" |
1068 | An unspecified error has occurred, the watcher has been stopped. This might |
1336 | An unspecified error has occurred, the watcher has been stopped. This might |
1069 | happen because the watcher could not be properly started because libev |
1337 | 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 |
1347 | 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 |
1348 | 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 |
1349 | 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 |
1350 | programs, though, as the fd could already be closed and reused for another |
1083 | thing, so beware. |
1351 | thing, so beware. |
1084 | .Sh "\s-1GENERIC\s0 \s-1WATCHER\s0 \s-1FUNCTIONS\s0" |
1352 | .SS "\s-1GENERIC\s0 \s-1WATCHER\s0 \s-1FUNCTIONS\s0" |
1085 | .IX Subsection "GENERIC WATCHER FUNCTIONS" |
1353 | .IX Subsection "GENERIC WATCHER FUNCTIONS" |
1086 | .ie n .IP """ev_init"" (ev_TYPE *watcher, callback)" 4 |
1354 | .ie n .IP """ev_init"" (ev_TYPE *watcher, callback)" 4 |
1087 | .el .IP "\f(CWev_init\fR (ev_TYPE *watcher, callback)" 4 |
1355 | .el .IP "\f(CWev_init\fR (ev_TYPE *watcher, callback)" 4 |
1088 | .IX Item "ev_init (ev_TYPE *watcher, callback)" |
1356 | .IX Item "ev_init (ev_TYPE *watcher, callback)" |
1089 | This macro initialises the generic portion of a watcher. The contents |
1357 | This macro initialises the generic portion of a watcher. The contents |
… | |
… | |
1104 | .Vb 3 |
1372 | .Vb 3 |
1105 | \& ev_io w; |
1373 | \& ev_io w; |
1106 | \& ev_init (&w, my_cb); |
1374 | \& ev_init (&w, my_cb); |
1107 | \& ev_io_set (&w, STDIN_FILENO, EV_READ); |
1375 | \& ev_io_set (&w, STDIN_FILENO, EV_READ); |
1108 | .Ve |
1376 | .Ve |
1109 | .ie n .IP """ev_TYPE_set"" (ev_TYPE *, [args])" 4 |
1377 | .ie n .IP """ev_TYPE_set"" (ev_TYPE *watcher, [args])" 4 |
1110 | .el .IP "\f(CWev_TYPE_set\fR (ev_TYPE *, [args])" 4 |
1378 | .el .IP "\f(CWev_TYPE_set\fR (ev_TYPE *watcher, [args])" 4 |
1111 | .IX Item "ev_TYPE_set (ev_TYPE *, [args])" |
1379 | .IX Item "ev_TYPE_set (ev_TYPE *watcher, [args])" |
1112 | This macro initialises the type-specific parts of a watcher. You need to |
1380 | 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 |
1381 | 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 |
1382 | 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 |
1383 | 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). |
1384 | 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. |
1397 | Example: Initialise and set an \f(CW\*(C`ev_io\*(C'\fR watcher in one step. |
1130 | .Sp |
1398 | .Sp |
1131 | .Vb 1 |
1399 | .Vb 1 |
1132 | \& ev_io_init (&w, my_cb, STDIN_FILENO, EV_READ); |
1400 | \& ev_io_init (&w, my_cb, STDIN_FILENO, EV_READ); |
1133 | .Ve |
1401 | .Ve |
1134 | .ie n .IP """ev_TYPE_start"" (loop *, ev_TYPE *watcher)" 4 |
1402 | .ie n .IP """ev_TYPE_start"" (loop, ev_TYPE *watcher)" 4 |
1135 | .el .IP "\f(CWev_TYPE_start\fR (loop *, ev_TYPE *watcher)" 4 |
1403 | .el .IP "\f(CWev_TYPE_start\fR (loop, ev_TYPE *watcher)" 4 |
1136 | .IX Item "ev_TYPE_start (loop *, ev_TYPE *watcher)" |
1404 | .IX Item "ev_TYPE_start (loop, ev_TYPE *watcher)" |
1137 | Starts (activates) the given watcher. Only active watchers will receive |
1405 | Starts (activates) the given watcher. Only active watchers will receive |
1138 | events. If the watcher is already active nothing will happen. |
1406 | events. If the watcher is already active nothing will happen. |
1139 | .Sp |
1407 | .Sp |
1140 | Example: Start the \f(CW\*(C`ev_io\*(C'\fR watcher that is being abused as example in this |
1408 | Example: Start the \f(CW\*(C`ev_io\*(C'\fR watcher that is being abused as example in this |
1141 | whole section. |
1409 | whole section. |
1142 | .Sp |
1410 | .Sp |
1143 | .Vb 1 |
1411 | .Vb 1 |
1144 | \& ev_io_start (EV_DEFAULT_UC, &w); |
1412 | \& ev_io_start (EV_DEFAULT_UC, &w); |
1145 | .Ve |
1413 | .Ve |
1146 | .ie n .IP """ev_TYPE_stop"" (loop *, ev_TYPE *watcher)" 4 |
1414 | .ie n .IP """ev_TYPE_stop"" (loop, ev_TYPE *watcher)" 4 |
1147 | .el .IP "\f(CWev_TYPE_stop\fR (loop *, ev_TYPE *watcher)" 4 |
1415 | .el .IP "\f(CWev_TYPE_stop\fR (loop, ev_TYPE *watcher)" 4 |
1148 | .IX Item "ev_TYPE_stop (loop *, ev_TYPE *watcher)" |
1416 | .IX Item "ev_TYPE_stop (loop, ev_TYPE *watcher)" |
1149 | Stops the given watcher if active, and clears the pending status (whether |
1417 | Stops the given watcher if active, and clears the pending status (whether |
1150 | the watcher was active or not). |
1418 | the watcher was active or not). |
1151 | .Sp |
1419 | .Sp |
1152 | It is possible that stopped watchers are pending \- for example, |
1420 | It is possible that stopped watchers are pending \- for example, |
1153 | non-repeating timers are being stopped when they become pending \- but |
1421 | non-repeating timers are being stopped when they become pending \- but |
… | |
… | |
1172 | Returns the callback currently set on the watcher. |
1440 | Returns the callback currently set on the watcher. |
1173 | .IP "ev_cb_set (ev_TYPE *watcher, callback)" 4 |
1441 | .IP "ev_cb_set (ev_TYPE *watcher, callback)" 4 |
1174 | .IX Item "ev_cb_set (ev_TYPE *watcher, callback)" |
1442 | .IX Item "ev_cb_set (ev_TYPE *watcher, callback)" |
1175 | Change the callback. You can change the callback at virtually any time |
1443 | Change the callback. You can change the callback at virtually any time |
1176 | (modulo threads). |
1444 | (modulo threads). |
1177 | .IP "ev_set_priority (ev_TYPE *watcher, priority)" 4 |
1445 | .IP "ev_set_priority (ev_TYPE *watcher, int priority)" 4 |
1178 | .IX Item "ev_set_priority (ev_TYPE *watcher, priority)" |
1446 | .IX Item "ev_set_priority (ev_TYPE *watcher, int priority)" |
1179 | .PD 0 |
1447 | .PD 0 |
1180 | .IP "int ev_priority (ev_TYPE *watcher)" 4 |
1448 | .IP "int ev_priority (ev_TYPE *watcher)" 4 |
1181 | .IX Item "int ev_priority (ev_TYPE *watcher)" |
1449 | .IX Item "int ev_priority (ev_TYPE *watcher)" |
1182 | .PD |
1450 | .PD |
1183 | Set and query the priority of the watcher. The priority is a small |
1451 | 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 |
1452 | 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 |
1453 | (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 |
1454 | 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). |
1455 | from being executed (except for \f(CW\*(C`ev_idle\*(C'\fR watchers). |
1188 | .Sp |
1456 | .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 |
1457 | 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. |
1458 | you need to look at \f(CW\*(C`ev_idle\*(C'\fR watchers, which provide this functionality. |
1196 | .Sp |
1459 | .Sp |
1197 | You \fImust not\fR change the priority of a watcher as long as it is active or |
1460 | You \fImust not\fR change the priority of a watcher as long as it is active or |
1198 | pending. |
1461 | 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 |
1462 | .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 |
1463 | 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 |
1464 | 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. |
1465 | or might not have been clamped to the valid range. |
|
|
1466 | .Sp |
|
|
1467 | The default priority used by watchers when no priority has been set is |
|
|
1468 | always \f(CW0\fR, which is supposed to not be too high and not be too low :). |
|
|
1469 | .Sp |
|
|
1470 | See \*(L"\s-1WATCHER\s0 \s-1PRIORITY\s0 \s-1MODELS\s0\*(R", below, for a more thorough treatment of |
|
|
1471 | priorities. |
1206 | .IP "ev_invoke (loop, ev_TYPE *watcher, int revents)" 4 |
1472 | .IP "ev_invoke (loop, ev_TYPE *watcher, int revents)" 4 |
1207 | .IX Item "ev_invoke (loop, ev_TYPE *watcher, int revents)" |
1473 | .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 |
1474 | 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 |
1475 | \&\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 |
1476 | 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 |
1481 | 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. |
1482 | watcher isn't pending it does nothing and returns \f(CW0\fR. |
1217 | .Sp |
1483 | .Sp |
1218 | Sometimes it can be useful to \*(L"poll\*(R" a watcher instead of waiting for its |
1484 | 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. |
1485 | 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" |
1486 | .IP "ev_feed_event (loop, ev_TYPE *watcher, int revents)" 4 |
1221 | .IX Subsection "ASSOCIATING CUSTOM DATA WITH A WATCHER" |
1487 | .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 |
1488 | 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 |
1489 | 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 |
1490 | 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 |
1491 | 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 |
1492 | .Sp |
1227 | data: |
1493 | Stopping the watcher, letting libev invoke it, or calling |
|
|
1494 | \&\f(CW\*(C`ev_clear_pending\*(C'\fR will clear the pending event, even if the watcher was |
|
|
1495 | not started in the first place. |
|
|
1496 | .Sp |
|
|
1497 | See also \f(CW\*(C`ev_feed_fd_event\*(C'\fR and \f(CW\*(C`ev_feed_signal_event\*(C'\fR for related |
|
|
1498 | functions that do not need a watcher. |
1228 | .PP |
1499 | .PP |
|
|
1500 | 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 |
|
|
1501 | \&\s-1OWN\s0 \s-1COMPOSITE\s0 \s-1WATCHERS\s0\*(R" idioms. |
|
|
1502 | .SS "\s-1WATCHER\s0 \s-1STATES\s0" |
|
|
1503 | .IX Subsection "WATCHER STATES" |
|
|
1504 | There are various watcher states mentioned throughout this manual \- |
|
|
1505 | active, pending and so on. In this section these states and the rules to |
|
|
1506 | transition between them will be described in more detail \- and while these |
|
|
1507 | rules might look complicated, they usually do \*(L"the right thing\*(R". |
|
|
1508 | .IP "initialiased" 4 |
|
|
1509 | .IX Item "initialiased" |
|
|
1510 | Before a watcher can be registered with the event loop it has to be |
|
|
1511 | initialised. This can be done with a call to \f(CW\*(C`ev_TYPE_init\*(C'\fR, or calls to |
|
|
1512 | \&\f(CW\*(C`ev_init\*(C'\fR followed by the watcher-specific \f(CW\*(C`ev_TYPE_set\*(C'\fR function. |
|
|
1513 | .Sp |
|
|
1514 | In this state it is simply some block of memory that is suitable for |
|
|
1515 | use in an event loop. It can be moved around, freed, reused etc. at |
|
|
1516 | will \- as long as you either keep the memory contents intact, or call |
|
|
1517 | \&\f(CW\*(C`ev_TYPE_init\*(C'\fR again. |
|
|
1518 | .IP "started/running/active" 4 |
|
|
1519 | .IX Item "started/running/active" |
|
|
1520 | Once a watcher has been started with a call to \f(CW\*(C`ev_TYPE_start\*(C'\fR it becomes |
|
|
1521 | property of the event loop, and is actively waiting for events. While in |
|
|
1522 | this state it cannot be accessed (except in a few documented ways), moved, |
|
|
1523 | freed or anything else \- the only legal thing is to keep a pointer to it, |
|
|
1524 | and call libev functions on it that are documented to work on active watchers. |
|
|
1525 | .IP "pending" 4 |
|
|
1526 | .IX Item "pending" |
|
|
1527 | If a watcher is active and libev determines that an event it is interested |
|
|
1528 | in has occurred (such as a timer expiring), it will become pending. It will |
|
|
1529 | stay in this pending state until either it is stopped or its callback is |
|
|
1530 | about to be invoked, so it is not normally pending inside the watcher |
|
|
1531 | callback. |
|
|
1532 | .Sp |
|
|
1533 | The watcher might or might not be active while it is pending (for example, |
|
|
1534 | an expired non-repeating timer can be pending but no longer active). If it |
|
|
1535 | is stopped, it can be freely accessed (e.g. by calling \f(CW\*(C`ev_TYPE_set\*(C'\fR), |
|
|
1536 | but it is still property of the event loop at this time, so cannot be |
|
|
1537 | moved, freed or reused. And if it is active the rules described in the |
|
|
1538 | previous item still apply. |
|
|
1539 | .Sp |
|
|
1540 | It is also possible to feed an event on a watcher that is not active (e.g. |
|
|
1541 | via \f(CW\*(C`ev_feed_event\*(C'\fR), in which case it becomes pending without being |
|
|
1542 | active. |
|
|
1543 | .IP "stopped" 4 |
|
|
1544 | .IX Item "stopped" |
|
|
1545 | A watcher can be stopped implicitly by libev (in which case it might still |
|
|
1546 | be pending), or explicitly by calling its \f(CW\*(C`ev_TYPE_stop\*(C'\fR function. The |
|
|
1547 | latter will clear any pending state the watcher might be in, regardless |
|
|
1548 | of whether it was active or not, so stopping a watcher explicitly before |
|
|
1549 | freeing it is often a good idea. |
|
|
1550 | .Sp |
|
|
1551 | While stopped (and not pending) the watcher is essentially in the |
|
|
1552 | initialised state, that is, it can be reused, moved, modified in any way |
|
|
1553 | you wish (but when you trash the memory block, you need to \f(CW\*(C`ev_TYPE_init\*(C'\fR |
|
|
1554 | it again). |
|
|
1555 | .SS "\s-1WATCHER\s0 \s-1PRIORITY\s0 \s-1MODELS\s0" |
|
|
1556 | .IX Subsection "WATCHER PRIORITY MODELS" |
|
|
1557 | Many event loops support \fIwatcher priorities\fR, which are usually small |
|
|
1558 | integers that influence the ordering of event callback invocation |
|
|
1559 | between watchers in some way, all else being equal. |
|
|
1560 | .PP |
|
|
1561 | In libev, Watcher priorities can be set using \f(CW\*(C`ev_set_priority\*(C'\fR. See its |
|
|
1562 | description for the more technical details such as the actual priority |
|
|
1563 | range. |
|
|
1564 | .PP |
|
|
1565 | There are two common ways how these these priorities are being interpreted |
|
|
1566 | by event loops: |
|
|
1567 | .PP |
|
|
1568 | In the more common lock-out model, higher priorities \*(L"lock out\*(R" invocation |
|
|
1569 | of lower priority watchers, which means as long as higher priority |
|
|
1570 | watchers receive events, lower priority watchers are not being invoked. |
|
|
1571 | .PP |
|
|
1572 | The less common only-for-ordering model uses priorities solely to order |
|
|
1573 | callback invocation within a single event loop iteration: Higher priority |
|
|
1574 | watchers are invoked before lower priority ones, but they all get invoked |
|
|
1575 | before polling for new events. |
|
|
1576 | .PP |
|
|
1577 | Libev uses the second (only-for-ordering) model for all its watchers |
|
|
1578 | except for idle watchers (which use the lock-out model). |
|
|
1579 | .PP |
|
|
1580 | The rationale behind this is that implementing the lock-out model for |
|
|
1581 | watchers is not well supported by most kernel interfaces, and most event |
|
|
1582 | libraries will just poll for the same events again and again as long as |
|
|
1583 | their callbacks have not been executed, which is very inefficient in the |
|
|
1584 | common case of one high-priority watcher locking out a mass of lower |
|
|
1585 | priority ones. |
|
|
1586 | .PP |
|
|
1587 | Static (ordering) priorities are most useful when you have two or more |
|
|
1588 | watchers handling the same resource: a typical usage example is having an |
|
|
1589 | \&\f(CW\*(C`ev_io\*(C'\fR watcher to receive data, and an associated \f(CW\*(C`ev_timer\*(C'\fR to handle |
|
|
1590 | timeouts. Under load, data might be received while the program handles |
|
|
1591 | other jobs, but since timers normally get invoked first, the timeout |
|
|
1592 | handler will be executed before checking for data. In that case, giving |
|
|
1593 | the timer a lower priority than the I/O watcher ensures that I/O will be |
|
|
1594 | handled first even under adverse conditions (which is usually, but not |
|
|
1595 | always, what you want). |
|
|
1596 | .PP |
|
|
1597 | Since idle watchers use the \*(L"lock-out\*(R" model, meaning that idle watchers |
|
|
1598 | will only be executed when no same or higher priority watchers have |
|
|
1599 | received events, they can be used to implement the \*(L"lock-out\*(R" model when |
|
|
1600 | required. |
|
|
1601 | .PP |
|
|
1602 | For example, to emulate how many other event libraries handle priorities, |
|
|
1603 | you can associate an \f(CW\*(C`ev_idle\*(C'\fR watcher to each such watcher, and in |
|
|
1604 | the normal watcher callback, you just start the idle watcher. The real |
|
|
1605 | processing is done in the idle watcher callback. This causes libev to |
|
|
1606 | continuously poll and process kernel event data for the watcher, but when |
|
|
1607 | the lock-out case is known to be rare (which in turn is rare :), this is |
|
|
1608 | workable. |
|
|
1609 | .PP |
|
|
1610 | Usually, however, the lock-out model implemented that way will perform |
|
|
1611 | miserably under the type of load it was designed to handle. In that case, |
|
|
1612 | it might be preferable to stop the real watcher before starting the |
|
|
1613 | idle watcher, so the kernel will not have to process the event in case |
|
|
1614 | the actual processing will be delayed for considerable time. |
|
|
1615 | .PP |
|
|
1616 | Here is an example of an I/O watcher that should run at a strictly lower |
|
|
1617 | priority than the default, and which should only process data when no |
|
|
1618 | other events are pending: |
|
|
1619 | .PP |
1229 | .Vb 7 |
1620 | .Vb 2 |
1230 | \& struct my_io |
1621 | \& ev_idle idle; // actual processing watcher |
|
|
1622 | \& ev_io io; // actual event watcher |
|
|
1623 | \& |
|
|
1624 | \& static void |
|
|
1625 | \& io_cb (EV_P_ ev_io *w, int revents) |
1231 | \& { |
1626 | \& { |
1232 | \& ev_io io; |
1627 | \& // stop the I/O watcher, we received the event, but |
1233 | \& int otherfd; |
1628 | \& // are not yet ready to handle it. |
1234 | \& void *somedata; |
1629 | \& ev_io_stop (EV_A_ w); |
1235 | \& struct whatever *mostinteresting; |
1630 | \& |
|
|
1631 | \& // start the idle watcher to handle the actual event. |
|
|
1632 | \& // it will not be executed as long as other watchers |
|
|
1633 | \& // with the default priority are receiving events. |
|
|
1634 | \& ev_idle_start (EV_A_ &idle); |
1236 | \& }; |
1635 | \& } |
1237 | \& |
1636 | \& |
1238 | \& ... |
1637 | \& static void |
1239 | \& struct my_io w; |
1638 | \& idle_cb (EV_P_ ev_idle *w, int revents) |
1240 | \& ev_io_init (&w.io, my_cb, fd, EV_READ); |
|
|
1241 | .Ve |
|
|
1242 | .PP |
|
|
1243 | And since your callback will be called with a pointer to the watcher, you |
|
|
1244 | can cast it back to your own type: |
|
|
1245 | .PP |
|
|
1246 | .Vb 5 |
|
|
1247 | \& static void my_cb (struct ev_loop *loop, ev_io *w_, int revents) |
|
|
1248 | \& { |
1639 | \& { |
1249 | \& struct my_io *w = (struct my_io *)w_; |
1640 | \& // actual processing |
1250 | \& ... |
1641 | \& read (STDIN_FILENO, ...); |
|
|
1642 | \& |
|
|
1643 | \& // have to start the I/O watcher again, as |
|
|
1644 | \& // we have handled the event |
|
|
1645 | \& ev_io_start (EV_P_ &io); |
1251 | \& } |
1646 | \& } |
1252 | .Ve |
|
|
1253 | .PP |
|
|
1254 | More interesting and less C\-conformant ways of casting your callback type |
|
|
1255 | instead have been omitted. |
|
|
1256 | .PP |
|
|
1257 | Another common scenario is to use some data structure with multiple |
|
|
1258 | embedded watchers: |
|
|
1259 | .PP |
|
|
1260 | .Vb 6 |
|
|
1261 | \& struct my_biggy |
|
|
1262 | \& { |
|
|
1263 | \& int some_data; |
|
|
1264 | \& ev_timer t1; |
|
|
1265 | \& ev_timer t2; |
|
|
1266 | \& } |
|
|
1267 | .Ve |
|
|
1268 | .PP |
|
|
1269 | In this case getting the pointer to \f(CW\*(C`my_biggy\*(C'\fR is a bit more |
|
|
1270 | complicated: Either you store the address of your \f(CW\*(C`my_biggy\*(C'\fR struct |
|
|
1271 | in the \f(CW\*(C`data\*(C'\fR member of the watcher (for woozies), or you need to use |
|
|
1272 | some pointer arithmetic using \f(CW\*(C`offsetof\*(C'\fR inside your watchers (for real |
|
|
1273 | programmers): |
|
|
1274 | .PP |
|
|
1275 | .Vb 1 |
|
|
1276 | \& #include <stddef.h> |
|
|
1277 | \& |
1647 | \& |
1278 | \& static void |
1648 | \& // initialisation |
1279 | \& t1_cb (EV_P_ ev_timer *w, int revents) |
1649 | \& ev_idle_init (&idle, idle_cb); |
1280 | \& { |
1650 | \& ev_io_init (&io, io_cb, STDIN_FILENO, EV_READ); |
1281 | \& struct my_biggy big = (struct my_biggy * |
1651 | \& ev_io_start (EV_DEFAULT_ &io); |
1282 | \& (((char *)w) \- offsetof (struct my_biggy, t1)); |
|
|
1283 | \& } |
|
|
1284 | \& |
|
|
1285 | \& static void |
|
|
1286 | \& t2_cb (EV_P_ ev_timer *w, int revents) |
|
|
1287 | \& { |
|
|
1288 | \& struct my_biggy big = (struct my_biggy * |
|
|
1289 | \& (((char *)w) \- offsetof (struct my_biggy, t2)); |
|
|
1290 | \& } |
|
|
1291 | .Ve |
1652 | .Ve |
|
|
1653 | .PP |
|
|
1654 | In the \*(L"real\*(R" world, it might also be beneficial to start a timer, so that |
|
|
1655 | low-priority connections can not be locked out forever under load. This |
|
|
1656 | enables your program to keep a lower latency for important connections |
|
|
1657 | during short periods of high load, while not completely locking out less |
|
|
1658 | important ones. |
1292 | .SH "WATCHER TYPES" |
1659 | .SH "WATCHER TYPES" |
1293 | .IX Header "WATCHER TYPES" |
1660 | .IX Header "WATCHER TYPES" |
1294 | This section describes each watcher in detail, but will not repeat |
1661 | This section describes each watcher in detail, but will not repeat |
1295 | information given in the last section. Any initialisation/set macros, |
1662 | information given in the last section. Any initialisation/set macros, |
1296 | functions and members specific to the watcher type are explained. |
1663 | functions and members specific to the watcher type are explained. |
… | |
… | |
1301 | watcher is stopped to your hearts content), or \fI[read\-write]\fR, which |
1668 | 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 |
1669 | 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 |
1670 | 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 |
1671 | sensible or take immediate effect (or do anything at all), but libev will |
1305 | not crash or malfunction in any way. |
1672 | not crash or malfunction in any way. |
1306 | .ie n .Sh """ev_io"" \- is this file descriptor readable or writable?" |
1673 | .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?" |
1674 | .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?" |
1675 | .IX Subsection "ev_io - is this file descriptor readable or writable?" |
1309 | I/O watchers check whether a file descriptor is readable or writable |
1676 | 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 |
1677 | 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 |
1678 | 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 |
1679 | 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 |
1684 | 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 |
1685 | 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 |
1686 | descriptors to non-blocking mode is also usually a good idea (but not |
1320 | required if you know what you are doing). |
1687 | required if you know what you are doing). |
1321 | .PP |
1688 | .PP |
1322 | If you cannot use non-blocking mode, then force the use of a |
|
|
1323 | known-to-be-good backend (at the time of this writing, this includes only |
|
|
1324 | \&\f(CW\*(C`EVBACKEND_SELECT\*(C'\fR and \f(CW\*(C`EVBACKEND_POLL\*(C'\fR). |
|
|
1325 | .PP |
|
|
1326 | Another thing you have to watch out for is that it is quite easy to |
1689 | 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 |
1690 | 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 |
1691 | 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 |
1692 | 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 |
1693 | with a relatively standard program structure. Thus it is best to always |
1331 | this situation even with a relatively standard program structure. Thus |
1694 | 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 |
|
|
1333 | \&\f(CW\*(C`EAGAIN\*(C'\fR is far preferable to a program hanging until some data arrives. |
1695 | preferable to a program hanging until some data arrives. |
1334 | .PP |
1696 | .PP |
1335 | If you cannot run the fd in non-blocking mode (for example you should |
1697 | 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 |
1698 | 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 |
1699 | 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 |
1700 | 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 |
1701 | 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 |
1702 | use \f(CW\*(C`SIGALRM\*(C'\fR and an interval timer, just to be sure you won't block |
1341 | indefinitely. |
1703 | indefinitely. |
1342 | .PP |
1704 | .PP |
1343 | But really, best use non-blocking mode. |
1705 | But really, best use non-blocking mode. |
1344 | .PP |
1706 | .PP |
… | |
… | |
1374 | .PP |
1736 | .PP |
1375 | There is no workaround possible except not registering events |
1737 | 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 |
1738 | 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. |
1739 | \&\f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or \f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
1378 | .PP |
1740 | .PP |
|
|
1741 | \fIThe special problem of files\fR |
|
|
1742 | .IX Subsection "The special problem of files" |
|
|
1743 | .PP |
|
|
1744 | Many people try to use \f(CW\*(C`select\*(C'\fR (or libev) on file descriptors |
|
|
1745 | representing files, and expect it to become ready when their program |
|
|
1746 | doesn't block on disk accesses (which can take a long time on their own). |
|
|
1747 | .PP |
|
|
1748 | However, this cannot ever work in the \*(L"expected\*(R" way \- you get a readiness |
|
|
1749 | notification as soon as the kernel knows whether and how much data is |
|
|
1750 | there, and in the case of open files, that's always the case, so you |
|
|
1751 | always get a readiness notification instantly, and your read (or possibly |
|
|
1752 | write) will still block on the disk I/O. |
|
|
1753 | .PP |
|
|
1754 | Another way to view it is that in the case of sockets, pipes, character |
|
|
1755 | devices and so on, there is another party (the sender) that delivers data |
|
|
1756 | on its own, but in the case of files, there is no such thing: the disk |
|
|
1757 | will not send data on its own, simply because it doesn't know what you |
|
|
1758 | wish to read \- you would first have to request some data. |
|
|
1759 | .PP |
|
|
1760 | Since files are typically not-so-well supported by advanced notification |
|
|
1761 | mechanism, libev tries hard to emulate \s-1POSIX\s0 behaviour with respect |
|
|
1762 | to files, even though you should not use it. The reason for this is |
|
|
1763 | convenience: sometimes you want to watch \s-1STDIN\s0 or \s-1STDOUT\s0, which is |
|
|
1764 | usually a tty, often a pipe, but also sometimes files or special devices |
|
|
1765 | (for example, \f(CW\*(C`epoll\*(C'\fR on Linux works with \fI/dev/random\fR but not with |
|
|
1766 | \&\fI/dev/urandom\fR), and even though the file might better be served with |
|
|
1767 | asynchronous I/O instead of with non-blocking I/O, it is still useful when |
|
|
1768 | it \*(L"just works\*(R" instead of freezing. |
|
|
1769 | .PP |
|
|
1770 | So avoid file descriptors pointing to files when you know it (e.g. use |
|
|
1771 | libeio), but use them when it is convenient, e.g. for \s-1STDIN/STDOUT\s0, or |
|
|
1772 | when you rarely read from a file instead of from a socket, and want to |
|
|
1773 | reuse the same code path. |
|
|
1774 | .PP |
1379 | \fIThe special problem of fork\fR |
1775 | \fIThe special problem of fork\fR |
1380 | .IX Subsection "The special problem of fork" |
1776 | .IX Subsection "The special problem of fork" |
1381 | .PP |
1777 | .PP |
1382 | Some backends (epoll, kqueue) do not support \f(CW\*(C`fork ()\*(C'\fR at all or exhibit |
1778 | 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 |
1779 | useless behaviour. Libev fully supports fork, but needs to be told about |
1384 | it in the child. |
1780 | it in the child if you want to continue to use it in the child. |
1385 | .PP |
1781 | .PP |
1386 | To support fork in your programs, you either have to call |
1782 | 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, |
1783 | ()\*(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 |
1784 | \&\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 |
1785 | .PP |
1391 | \fIThe special problem of \s-1SIGPIPE\s0\fR |
1786 | \fIThe special problem of \s-1SIGPIPE\s0\fR |
1392 | .IX Subsection "The special problem of SIGPIPE" |
1787 | .IX Subsection "The special problem of SIGPIPE" |
1393 | .PP |
1788 | .PP |
1394 | While not really specific to libev, it is easy to forget about \f(CW\*(C`SIGPIPE\*(C'\fR: |
1789 | 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. |
1792 | this is sensible behaviour, for daemons, this is usually undesirable. |
1398 | .PP |
1793 | .PP |
1399 | So when you encounter spurious, unexplained daemon exits, make sure you |
1794 | 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 |
1795 | 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). |
1796 | somewhere, as that would have given you a big clue). |
|
|
1797 | .PP |
|
|
1798 | \fIThe special problem of \fIaccept()\fIing when you can't\fR |
|
|
1799 | .IX Subsection "The special problem of accept()ing when you can't" |
|
|
1800 | .PP |
|
|
1801 | Many implementations of the \s-1POSIX\s0 \f(CW\*(C`accept\*(C'\fR function (for example, |
|
|
1802 | found in post\-2004 Linux) have the peculiar behaviour of not removing a |
|
|
1803 | connection from the pending queue in all error cases. |
|
|
1804 | .PP |
|
|
1805 | For example, larger servers often run out of file descriptors (because |
|
|
1806 | of resource limits), causing \f(CW\*(C`accept\*(C'\fR to fail with \f(CW\*(C`ENFILE\*(C'\fR but not |
|
|
1807 | rejecting the connection, leading to libev signalling readiness on |
|
|
1808 | the next iteration again (the connection still exists after all), and |
|
|
1809 | typically causing the program to loop at 100% \s-1CPU\s0 usage. |
|
|
1810 | .PP |
|
|
1811 | Unfortunately, the set of errors that cause this issue differs between |
|
|
1812 | operating systems, there is usually little the app can do to remedy the |
|
|
1813 | situation, and no known thread-safe method of removing the connection to |
|
|
1814 | cope with overload is known (to me). |
|
|
1815 | .PP |
|
|
1816 | One of the easiest ways to handle this situation is to just ignore it |
|
|
1817 | \&\- when the program encounters an overload, it will just loop until the |
|
|
1818 | situation is over. While this is a form of busy waiting, no \s-1OS\s0 offers an |
|
|
1819 | event-based way to handle this situation, so it's the best one can do. |
|
|
1820 | .PP |
|
|
1821 | A better way to handle the situation is to log any errors other than |
|
|
1822 | \&\f(CW\*(C`EAGAIN\*(C'\fR and \f(CW\*(C`EWOULDBLOCK\*(C'\fR, making sure not to flood the log with such |
|
|
1823 | messages, and continue as usual, which at least gives the user an idea of |
|
|
1824 | what could be wrong (\*(L"raise the ulimit!\*(R"). For extra points one could stop |
|
|
1825 | the \f(CW\*(C`ev_io\*(C'\fR watcher on the listening fd \*(L"for a while\*(R", which reduces \s-1CPU\s0 |
|
|
1826 | usage. |
|
|
1827 | .PP |
|
|
1828 | If your program is single-threaded, then you could also keep a dummy file |
|
|
1829 | descriptor for overload situations (e.g. by opening \fI/dev/null\fR), and |
|
|
1830 | 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, |
|
|
1831 | close that fd, and create a new dummy fd. This will gracefully refuse |
|
|
1832 | clients under typical overload conditions. |
|
|
1833 | .PP |
|
|
1834 | The last way to handle it is to simply log the error and \f(CW\*(C`exit\*(C'\fR, as |
|
|
1835 | is often done with \f(CW\*(C`malloc\*(C'\fR failures, but this results in an easy |
|
|
1836 | opportunity for a DoS attack. |
1402 | .PP |
1837 | .PP |
1403 | \fIWatcher-Specific Functions\fR |
1838 | \fIWatcher-Specific Functions\fR |
1404 | .IX Subsection "Watcher-Specific Functions" |
1839 | .IX Subsection "Watcher-Specific Functions" |
1405 | .IP "ev_io_init (ev_io *, callback, int fd, int events)" 4 |
1840 | .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)" |
1841 | .IX Item "ev_io_init (ev_io *, callback, int fd, int events)" |
… | |
… | |
1436 | \& ... |
1871 | \& ... |
1437 | \& struct ev_loop *loop = ev_default_init (0); |
1872 | \& struct ev_loop *loop = ev_default_init (0); |
1438 | \& ev_io stdin_readable; |
1873 | \& ev_io stdin_readable; |
1439 | \& ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ); |
1874 | \& ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ); |
1440 | \& ev_io_start (loop, &stdin_readable); |
1875 | \& ev_io_start (loop, &stdin_readable); |
1441 | \& ev_loop (loop, 0); |
1876 | \& ev_run (loop, 0); |
1442 | .Ve |
1877 | .Ve |
1443 | .ie n .Sh """ev_timer"" \- relative and optionally repeating timeouts" |
1878 | .ie n .SS """ev_timer"" \- relative and optionally repeating timeouts" |
1444 | .el .Sh "\f(CWev_timer\fP \- relative and optionally repeating timeouts" |
1879 | .el .SS "\f(CWev_timer\fP \- relative and optionally repeating timeouts" |
1445 | .IX Subsection "ev_timer - relative and optionally repeating timeouts" |
1880 | .IX Subsection "ev_timer - relative and optionally repeating timeouts" |
1446 | Timer watchers are simple relative timers that generate an event after a |
1881 | Timer watchers are simple relative timers that generate an event after a |
1447 | given time, and optionally repeating in regular intervals after that. |
1882 | given time, and optionally repeating in regular intervals after that. |
1448 | .PP |
1883 | .PP |
1449 | The timers are based on real time, that is, if you register an event that |
1884 | 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 |
1886 | 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 |
1887 | detecting time jumps is hard, and some inaccuracies are unavoidable (the |
1453 | monotonic clock option helps a lot here). |
1888 | monotonic clock option helps a lot here). |
1454 | .PP |
1889 | .PP |
1455 | The callback is guaranteed to be invoked only \fIafter\fR its timeout has |
1890 | 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 |
1891 | passed (not \fIat\fR, so on systems with very low-resolution clocks this |
1457 | then order of execution is undefined. |
1892 | might introduce a small delay, see \*(L"the special problem of being too |
|
|
1893 | early\*(R", below). If multiple timers become ready during the same loop |
|
|
1894 | iteration then the ones with earlier time-out values are invoked before |
|
|
1895 | ones of the same priority with later time-out values (but this is no |
|
|
1896 | longer true when a callback calls \f(CW\*(C`ev_run\*(C'\fR recursively). |
1458 | .PP |
1897 | .PP |
1459 | \fIBe smart about timeouts\fR |
1898 | \fIBe smart about timeouts\fR |
1460 | .IX Subsection "Be smart about timeouts" |
1899 | .IX Subsection "Be smart about timeouts" |
1461 | .PP |
1900 | .PP |
1462 | Many real-world problems involve some kind of timeout, usually for error |
1901 | Many real-world problems involve some kind of timeout, usually for error |
… | |
… | |
1509 | member and \f(CW\*(C`ev_timer_again\*(C'\fR. |
1948 | member and \f(CW\*(C`ev_timer_again\*(C'\fR. |
1510 | .Sp |
1949 | .Sp |
1511 | At start: |
1950 | At start: |
1512 | .Sp |
1951 | .Sp |
1513 | .Vb 3 |
1952 | .Vb 3 |
1514 | \& ev_timer_init (timer, callback); |
1953 | \& ev_init (timer, callback); |
1515 | \& timer\->repeat = 60.; |
1954 | \& timer\->repeat = 60.; |
1516 | \& ev_timer_again (loop, timer); |
1955 | \& ev_timer_again (loop, timer); |
1517 | .Ve |
1956 | .Ve |
1518 | .Sp |
1957 | .Sp |
1519 | Each time there is some activity: |
1958 | Each time there is some activity: |
… | |
… | |
1544 | .Sp |
1983 | .Sp |
1545 | In this case, it would be more efficient to leave the \f(CW\*(C`ev_timer\*(C'\fR alone, |
1984 | In this case, it would be more efficient to leave the \f(CW\*(C`ev_timer\*(C'\fR alone, |
1546 | but remember the time of last activity, and check for a real timeout only |
1985 | but remember the time of last activity, and check for a real timeout only |
1547 | within the callback: |
1986 | within the callback: |
1548 | .Sp |
1987 | .Sp |
1549 | .Vb 1 |
1988 | .Vb 3 |
|
|
1989 | \& ev_tstamp timeout = 60.; |
1550 | \& ev_tstamp last_activity; // time of last activity |
1990 | \& ev_tstamp last_activity; // time of last activity |
|
|
1991 | \& ev_timer timer; |
1551 | \& |
1992 | \& |
1552 | \& static void |
1993 | \& static void |
1553 | \& callback (EV_P_ ev_timer *w, int revents) |
1994 | \& callback (EV_P_ ev_timer *w, int revents) |
1554 | \& { |
1995 | \& { |
1555 | \& ev_tstamp now = ev_now (EV_A); |
1996 | \& // calculate when the timeout would happen |
1556 | \& ev_tstamp timeout = last_activity + 60.; |
1997 | \& ev_tstamp after = last_activity \- ev_now (EV_A) + timeout; |
1557 | \& |
1998 | \& |
1558 | \& // if last_activity + 60. is older than now, we did time out |
1999 | \& // if negative, it means we the timeout already occured |
1559 | \& if (timeout < now) |
2000 | \& if (after < 0.) |
1560 | \& { |
2001 | \& { |
1561 | \& // timeout occured, take action |
2002 | \& // timeout occurred, take action |
1562 | \& } |
2003 | \& } |
1563 | \& else |
2004 | \& else |
1564 | \& { |
2005 | \& { |
1565 | \& // callback was invoked, but there was some activity, re\-arm |
2006 | \& // callback was invoked, but there was some recent |
1566 | \& // the watcher to fire in last_activity + 60, which is |
2007 | \& // activity. simply restart the timer to time out |
1567 | \& // guaranteed to be in the future, so "again" is positive: |
2008 | \& // after "after" seconds, which is the earliest time |
1568 | \& w\->repeat = timeout \- now; |
2009 | \& // the timeout can occur. |
|
|
2010 | \& ev_timer_set (w, after, 0.); |
1569 | \& ev_timer_again (EV_A_ w); |
2011 | \& ev_timer_start (EV_A_ w); |
1570 | \& } |
2012 | \& } |
1571 | \& } |
2013 | \& } |
1572 | .Ve |
2014 | .Ve |
1573 | .Sp |
2015 | .Sp |
1574 | To summarise the callback: first calculate the real timeout (defined |
2016 | To summarise the callback: first calculate in how many seconds the |
1575 | as \*(L"60 seconds after the last activity\*(R"), then check if that time has |
2017 | timeout will occur (by calculating the absolute time when it would occur, |
1576 | been reached, which means something \fIdid\fR, in fact, time out. Otherwise |
2018 | \&\f(CW\*(C`last_activity + timeout\*(C'\fR, and subtracting the current time, \f(CW\*(C`ev_now |
1577 | the callback was invoked too early (\f(CW\*(C`timeout\*(C'\fR is in the future), so |
2019 | (EV_A)\*(C'\fR from that). |
1578 | re-schedule the timer to fire at that future time, to see if maybe we have |
|
|
1579 | a timeout then. |
|
|
1580 | .Sp |
2020 | .Sp |
1581 | Note how \f(CW\*(C`ev_timer_again\*(C'\fR is used, taking advantage of the |
2021 | If this value is negative, then we are already past the timeout, i.e. we |
1582 | \&\f(CW\*(C`ev_timer_again\*(C'\fR optimisation when the timer is already running. |
2022 | timed out, and need to do whatever is needed in this case. |
|
|
2023 | .Sp |
|
|
2024 | Otherwise, we now the earliest time at which the timeout would trigger, |
|
|
2025 | and simply start the timer with this timeout value. |
|
|
2026 | .Sp |
|
|
2027 | In other words, each time the callback is invoked it will check whether |
|
|
2028 | the timeout cocured. If not, it will simply reschedule itself to check |
|
|
2029 | again at the earliest time it could time out. Rinse. Repeat. |
1583 | .Sp |
2030 | .Sp |
1584 | This scheme causes more callback invocations (about one every 60 seconds |
2031 | This scheme causes more callback invocations (about one every 60 seconds |
1585 | minus half the average time between activity), but virtually no calls to |
2032 | minus half the average time between activity), but virtually no calls to |
1586 | libev to change the timeout. |
2033 | libev to change the timeout. |
1587 | .Sp |
2034 | .Sp |
1588 | To start the timer, simply initialise the watcher and set \f(CW\*(C`last_activity\*(C'\fR |
2035 | To start the machinery, simply initialise the watcher and set |
1589 | to the current time (meaning we just have some activity :), then call the |
2036 | \&\f(CW\*(C`last_activity\*(C'\fR to the current time (meaning there was some activity just |
1590 | callback, which will \*(L"do the right thing\*(R" and start the timer: |
2037 | now), then call the callback, which will \*(L"do the right thing\*(R" and start |
|
|
2038 | the timer: |
1591 | .Sp |
2039 | .Sp |
1592 | .Vb 3 |
2040 | .Vb 3 |
|
|
2041 | \& last_activity = ev_now (EV_A); |
1593 | \& ev_timer_init (timer, callback); |
2042 | \& ev_init (&timer, callback); |
1594 | \& last_activity = ev_now (loop); |
2043 | \& callback (EV_A_ &timer, 0); |
1595 | \& callback (loop, timer, EV_TIMEOUT); |
|
|
1596 | .Ve |
2044 | .Ve |
1597 | .Sp |
2045 | .Sp |
1598 | And when there is some activity, simply store the current time in |
2046 | When there is some activity, simply store the current time in |
1599 | \&\f(CW\*(C`last_activity\*(C'\fR, no libev calls at all: |
2047 | \&\f(CW\*(C`last_activity\*(C'\fR, no libev calls at all: |
1600 | .Sp |
2048 | .Sp |
1601 | .Vb 1 |
2049 | .Vb 2 |
|
|
2050 | \& if (activity detected) |
1602 | \& last_actiivty = ev_now (loop); |
2051 | \& last_activity = ev_now (EV_A); |
|
|
2052 | .Ve |
|
|
2053 | .Sp |
|
|
2054 | When your timeout value changes, then the timeout can be changed by simply |
|
|
2055 | providing a new value, stopping the timer and calling the callback, which |
|
|
2056 | will agaion do the right thing (for example, time out immediately :). |
|
|
2057 | .Sp |
|
|
2058 | .Vb 3 |
|
|
2059 | \& timeout = new_value; |
|
|
2060 | \& ev_timer_stop (EV_A_ &timer); |
|
|
2061 | \& callback (EV_A_ &timer, 0); |
1603 | .Ve |
2062 | .Ve |
1604 | .Sp |
2063 | .Sp |
1605 | This technique is slightly more complex, but in most cases where the |
2064 | This technique is slightly more complex, but in most cases where the |
1606 | time-out is unlikely to be triggered, much more efficient. |
2065 | time-out is unlikely to be triggered, much more efficient. |
1607 | .Sp |
|
|
1608 | Changing the timeout is trivial as well (if it isn't hard-coded in the |
|
|
1609 | callback :) \- just change the timeout and invoke the callback, which will |
|
|
1610 | fix things for you. |
|
|
1611 | .IP "4. Wee, just use a double-linked list for your timeouts." 4 |
2066 | .IP "4. Wee, just use a double-linked list for your timeouts." 4 |
1612 | .IX Item "4. Wee, just use a double-linked list for your timeouts." |
2067 | .IX Item "4. Wee, just use a double-linked list for your timeouts." |
1613 | If there is not one request, but many thousands (millions...), all |
2068 | If there is not one request, but many thousands (millions...), all |
1614 | employing some kind of timeout with the same timeout value, then one can |
2069 | employing some kind of timeout with the same timeout value, then one can |
1615 | do even better: |
2070 | do even better: |
… | |
… | |
1639 | Method #1 is almost always a bad idea, and buys you nothing. Method #4 is |
2094 | Method #1 is almost always a bad idea, and buys you nothing. Method #4 is |
1640 | rather complicated, but extremely efficient, something that really pays |
2095 | rather complicated, but extremely efficient, something that really pays |
1641 | off after the first million or so of active timers, i.e. it's usually |
2096 | off after the first million or so of active timers, i.e. it's usually |
1642 | overkill :) |
2097 | overkill :) |
1643 | .PP |
2098 | .PP |
|
|
2099 | \fIThe special problem of being too early\fR |
|
|
2100 | .IX Subsection "The special problem of being too early" |
|
|
2101 | .PP |
|
|
2102 | If you ask a timer to call your callback after three seconds, then |
|
|
2103 | you expect it to be invoked after three seconds \- but of course, this |
|
|
2104 | cannot be guaranteed to infinite precision. Less obviously, it cannot be |
|
|
2105 | guaranteed to any precision by libev \- imagine somebody suspending the |
|
|
2106 | process with a \s-1STOP\s0 signal for a few hours for example. |
|
|
2107 | .PP |
|
|
2108 | So, libev tries to invoke your callback as soon as possible \fIafter\fR the |
|
|
2109 | delay has occurred, but cannot guarantee this. |
|
|
2110 | .PP |
|
|
2111 | A less obvious failure mode is calling your callback too early: many event |
|
|
2112 | loops compare timestamps with a \*(L"elapsed delay >= requested delay\*(R", but |
|
|
2113 | this can cause your callback to be invoked much earlier than you would |
|
|
2114 | expect. |
|
|
2115 | .PP |
|
|
2116 | To see why, imagine a system with a clock that only offers full second |
|
|
2117 | resolution (think windows if you can't come up with a broken enough \s-1OS\s0 |
|
|
2118 | yourself). If you schedule a one-second timer at the time 500.9, then the |
|
|
2119 | event loop will schedule your timeout to elapse at a system time of 500 |
|
|
2120 | (500.9 truncated to the resolution) + 1, or 501. |
|
|
2121 | .PP |
|
|
2122 | If an event library looks at the timeout 0.1s later, it will see \*(L"501 >= |
|
|
2123 | 501\*(R" and invoke the callback 0.1s after it was started, even though a |
|
|
2124 | one-second delay was requested \- this is being \*(L"too early\*(R", despite best |
|
|
2125 | intentions. |
|
|
2126 | .PP |
|
|
2127 | This is the reason why libev will never invoke the callback if the elapsed |
|
|
2128 | delay equals the requested delay, but only when the elapsed delay is |
|
|
2129 | larger than the requested delay. In the example above, libev would only invoke |
|
|
2130 | the callback at system time 502, or 1.1s after the timer was started. |
|
|
2131 | .PP |
|
|
2132 | So, while libev cannot guarantee that your callback will be invoked |
|
|
2133 | exactly when requested, it \fIcan\fR and \fIdoes\fR guarantee that the requested |
|
|
2134 | delay has actually elapsed, or in other words, it always errs on the \*(L"too |
|
|
2135 | late\*(R" side of things. |
|
|
2136 | .PP |
1644 | \fIThe special problem of time updates\fR |
2137 | \fIThe special problem of time updates\fR |
1645 | .IX Subsection "The special problem of time updates" |
2138 | .IX Subsection "The special problem of time updates" |
1646 | .PP |
2139 | .PP |
1647 | Establishing the current time is a costly operation (it usually takes at |
2140 | Establishing the current time is a costly operation (it usually takes |
1648 | least two system calls): \s-1EV\s0 therefore updates its idea of the current |
2141 | at least one system call): \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 |
2142 | 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 |
2143 | 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. |
2144 | lots of events in one iteration. |
1652 | .PP |
2145 | .PP |
1653 | The relative timeouts are calculated relative to the \f(CW\*(C`ev_now ()\*(C'\fR |
2146 | 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 |
2147 | time. This is usually the right thing as this timestamp refers to the time |
… | |
… | |
1661 | .Ve |
2154 | .Ve |
1662 | .PP |
2155 | .PP |
1663 | If the event loop is suspended for a long time, you can also force an |
2156 | 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 |
2157 | update of the time returned by \f(CW\*(C`ev_now ()\*(C'\fR by calling \f(CW\*(C`ev_now_update |
1665 | ()\*(C'\fR. |
2158 | ()\*(C'\fR. |
|
|
2159 | .PP |
|
|
2160 | \fIThe special problem of unsynchronised clocks\fR |
|
|
2161 | .IX Subsection "The special problem of unsynchronised clocks" |
|
|
2162 | .PP |
|
|
2163 | Modern systems have a variety of clocks \- libev itself uses the normal |
|
|
2164 | \&\*(L"wall clock\*(R" clock and, if available, the monotonic clock (to avoid time |
|
|
2165 | jumps). |
|
|
2166 | .PP |
|
|
2167 | Neither of these clocks is synchronised with each other or any other clock |
|
|
2168 | on the system, so \f(CW\*(C`ev_time ()\*(C'\fR might return a considerably different time |
|
|
2169 | than \f(CW\*(C`gettimeofday ()\*(C'\fR or \f(CW\*(C`time ()\*(C'\fR. On a GNU/Linux system, for example, |
|
|
2170 | a call to \f(CW\*(C`gettimeofday\*(C'\fR might return a second count that is one higher |
|
|
2171 | than a directly following call to \f(CW\*(C`time\*(C'\fR. |
|
|
2172 | .PP |
|
|
2173 | The moral of this is to only compare libev-related timestamps with |
|
|
2174 | \&\f(CW\*(C`ev_time ()\*(C'\fR and \f(CW\*(C`ev_now ()\*(C'\fR, at least if you want better precision than |
|
|
2175 | a second or so. |
|
|
2176 | .PP |
|
|
2177 | One more problem arises due to this lack of synchronisation: if libev uses |
|
|
2178 | the system monotonic clock and you compare timestamps from \f(CW\*(C`ev_time\*(C'\fR |
|
|
2179 | or \f(CW\*(C`ev_now\*(C'\fR from when you started your timer and when your callback is |
|
|
2180 | invoked, you will find that sometimes the callback is a bit \*(L"early\*(R". |
|
|
2181 | .PP |
|
|
2182 | This is because \f(CW\*(C`ev_timer\*(C'\fRs work in real time, not wall clock time, so |
|
|
2183 | libev makes sure your callback is not invoked before the delay happened, |
|
|
2184 | \&\fImeasured according to the real time\fR, not the system clock. |
|
|
2185 | .PP |
|
|
2186 | If your timeouts are based on a physical timescale (e.g. \*(L"time out this |
|
|
2187 | connection after 100 seconds\*(R") then this shouldn't bother you as it is |
|
|
2188 | exactly the right behaviour. |
|
|
2189 | .PP |
|
|
2190 | If you want to compare wall clock/system timestamps to your timers, then |
|
|
2191 | you need to use \f(CW\*(C`ev_periodic\*(C'\fRs, as these are based on the wall clock |
|
|
2192 | time, where your comparisons will always generate correct results. |
|
|
2193 | .PP |
|
|
2194 | \fIThe special problems of suspended animation\fR |
|
|
2195 | .IX Subsection "The special problems of suspended animation" |
|
|
2196 | .PP |
|
|
2197 | When you leave the server world it is quite customary to hit machines that |
|
|
2198 | can suspend/hibernate \- what happens to the clocks during such a suspend? |
|
|
2199 | .PP |
|
|
2200 | Some quick tests made with a Linux 2.6.28 indicate that a suspend freezes |
|
|
2201 | all processes, while the clocks (\f(CW\*(C`times\*(C'\fR, \f(CW\*(C`CLOCK_MONOTONIC\*(C'\fR) continue |
|
|
2202 | to run until the system is suspended, but they will not advance while the |
|
|
2203 | system is suspended. That means, on resume, it will be as if the program |
|
|
2204 | was frozen for a few seconds, but the suspend time will not be counted |
|
|
2205 | towards \f(CW\*(C`ev_timer\*(C'\fR when a monotonic clock source is used. The real time |
|
|
2206 | clock advanced as expected, but if it is used as sole clocksource, then a |
|
|
2207 | long suspend would be detected as a time jump by libev, and timers would |
|
|
2208 | be adjusted accordingly. |
|
|
2209 | .PP |
|
|
2210 | I would not be surprised to see different behaviour in different between |
|
|
2211 | operating systems, \s-1OS\s0 versions or even different hardware. |
|
|
2212 | .PP |
|
|
2213 | The other form of suspend (job control, or sending a \s-1SIGSTOP\s0) will see a |
|
|
2214 | time jump in the monotonic clocks and the realtime clock. If the program |
|
|
2215 | is suspended for a very long time, and monotonic clock sources are in use, |
|
|
2216 | then you can expect \f(CW\*(C`ev_timer\*(C'\fRs to expire as the full suspension time |
|
|
2217 | will be counted towards the timers. When no monotonic clock source is in |
|
|
2218 | use, then libev will again assume a timejump and adjust accordingly. |
|
|
2219 | .PP |
|
|
2220 | It might be beneficial for this latter case to call \f(CW\*(C`ev_suspend\*(C'\fR |
|
|
2221 | and \f(CW\*(C`ev_resume\*(C'\fR in code that handles \f(CW\*(C`SIGTSTP\*(C'\fR, to at least get |
|
|
2222 | deterministic behaviour in this case (you can do nothing against |
|
|
2223 | \&\f(CW\*(C`SIGSTOP\*(C'\fR). |
1666 | .PP |
2224 | .PP |
1667 | \fIWatcher-Specific Functions and Data Members\fR |
2225 | \fIWatcher-Specific Functions and Data Members\fR |
1668 | .IX Subsection "Watcher-Specific Functions and Data Members" |
2226 | .IX Subsection "Watcher-Specific Functions and Data Members" |
1669 | .IP "ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)" 4 |
2227 | .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)" |
2228 | .IX Item "ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)" |
… | |
… | |
1683 | trigger at exactly 10 second intervals. If, however, your program cannot |
2241 | trigger at exactly 10 second intervals. If, however, your program cannot |
1684 | keep up with the timer (because it takes longer than those 10 seconds to |
2242 | keep up with the timer (because it takes longer than those 10 seconds to |
1685 | do stuff) the timer will not fire more than once per event loop iteration. |
2243 | do stuff) the timer will not fire more than once per event loop iteration. |
1686 | .IP "ev_timer_again (loop, ev_timer *)" 4 |
2244 | .IP "ev_timer_again (loop, ev_timer *)" 4 |
1687 | .IX Item "ev_timer_again (loop, ev_timer *)" |
2245 | .IX Item "ev_timer_again (loop, ev_timer *)" |
1688 | This will act as if the timer timed out and restart it again if it is |
2246 | This will act as if the timer timed out, and restarts it again if it is |
1689 | repeating. The exact semantics are: |
2247 | repeating. It basically works like calling \f(CW\*(C`ev_timer_stop\*(C'\fR, updating the |
|
|
2248 | timeout to the \f(CW\*(C`repeat\*(C'\fR value and calling \f(CW\*(C`ev_timer_start\*(C'\fR. |
1690 | .Sp |
2249 | .Sp |
|
|
2250 | The exact semantics are as in the following rules, all of which will be |
|
|
2251 | applied to the watcher: |
|
|
2252 | .RS 4 |
1691 | If the timer is pending, its pending status is cleared. |
2253 | .IP "If the timer is pending, the pending status is always cleared." 4 |
1692 | .Sp |
2254 | .IX Item "If the timer is pending, the pending status is always cleared." |
|
|
2255 | .PD 0 |
1693 | If the timer is started but non-repeating, stop it (as if it timed out). |
2256 | .IP "If the timer is started but non-repeating, stop it (as if it timed out, without invoking it)." 4 |
1694 | .Sp |
2257 | .IX Item "If the timer is started but non-repeating, stop it (as if it timed out, without invoking it)." |
1695 | If the timer is repeating, either start it if necessary (with the |
2258 | .ie n .IP "If the timer is repeating, make the ""repeat"" value the new timeout and start the timer, if necessary." 4 |
1696 | \&\f(CW\*(C`repeat\*(C'\fR value), or reset the running timer to the \f(CW\*(C`repeat\*(C'\fR value. |
2259 | .el .IP "If the timer is repeating, make the \f(CWrepeat\fR value the new timeout and start the timer, if necessary." 4 |
|
|
2260 | .IX Item "If the timer is repeating, make the repeat value the new timeout and start the timer, if necessary." |
|
|
2261 | .RE |
|
|
2262 | .RS 4 |
|
|
2263 | .PD |
1697 | .Sp |
2264 | .Sp |
1698 | This sounds a bit complicated, see \*(L"Be smart about timeouts\*(R", above, for a |
2265 | This sounds a bit complicated, see \*(L"Be smart about timeouts\*(R", above, for a |
1699 | usage example. |
2266 | usage example. |
|
|
2267 | .RE |
|
|
2268 | .IP "ev_tstamp ev_timer_remaining (loop, ev_timer *)" 4 |
|
|
2269 | .IX Item "ev_tstamp ev_timer_remaining (loop, ev_timer *)" |
|
|
2270 | Returns the remaining time until a timer fires. If the timer is active, |
|
|
2271 | then this time is relative to the current event loop time, otherwise it's |
|
|
2272 | the timeout value currently configured. |
|
|
2273 | .Sp |
|
|
2274 | That is, after an \f(CW\*(C`ev_timer_set (w, 5, 7)\*(C'\fR, \f(CW\*(C`ev_timer_remaining\*(C'\fR returns |
|
|
2275 | \&\f(CW5\fR. When the timer is started and one second passes, \f(CW\*(C`ev_timer_remaining\*(C'\fR |
|
|
2276 | will return \f(CW4\fR. When the timer expires and is restarted, it will return |
|
|
2277 | roughly \f(CW7\fR (likely slightly less as callback invocation takes some time, |
|
|
2278 | too), and so on. |
1700 | .IP "ev_tstamp repeat [read\-write]" 4 |
2279 | .IP "ev_tstamp repeat [read\-write]" 4 |
1701 | .IX Item "ev_tstamp repeat [read-write]" |
2280 | .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 |
2281 | 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), |
2282 | 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. |
2283 | which is also when any modifications are taken into account. |
… | |
… | |
1731 | \& } |
2310 | \& } |
1732 | \& |
2311 | \& |
1733 | \& ev_timer mytimer; |
2312 | \& ev_timer mytimer; |
1734 | \& ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */ |
2313 | \& ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */ |
1735 | \& ev_timer_again (&mytimer); /* start timer */ |
2314 | \& ev_timer_again (&mytimer); /* start timer */ |
1736 | \& ev_loop (loop, 0); |
2315 | \& ev_run (loop, 0); |
1737 | \& |
2316 | \& |
1738 | \& // and in some piece of code that gets executed on any "activity": |
2317 | \& // and in some piece of code that gets executed on any "activity": |
1739 | \& // reset the timeout to start ticking again at 10 seconds |
2318 | \& // reset the timeout to start ticking again at 10 seconds |
1740 | \& ev_timer_again (&mytimer); |
2319 | \& ev_timer_again (&mytimer); |
1741 | .Ve |
2320 | .Ve |
1742 | .ie n .Sh """ev_periodic"" \- to cron or not to cron?" |
2321 | .ie n .SS """ev_periodic"" \- to cron or not to cron?" |
1743 | .el .Sh "\f(CWev_periodic\fP \- to cron or not to cron?" |
2322 | .el .SS "\f(CWev_periodic\fP \- to cron or not to cron?" |
1744 | .IX Subsection "ev_periodic - to cron or not to cron?" |
2323 | .IX Subsection "ev_periodic - to cron or not to cron?" |
1745 | Periodic watchers are also timers of a kind, but they are very versatile |
2324 | Periodic watchers are also timers of a kind, but they are very versatile |
1746 | (and unfortunately a bit complex). |
2325 | (and unfortunately a bit complex). |
1747 | .PP |
2326 | .PP |
1748 | Unlike \f(CW\*(C`ev_timer\*(C'\fR's, they are not based on real time (or relative time) |
2327 | 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 |
2328 | 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 |
2329 | (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 () |
2330 | 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 |
2331 | 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 |
2332 | 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 |
2333 | .PP |
|
|
2334 | You can tell a periodic watcher to trigger after some specific point |
|
|
2335 | in time: for example, if you tell a periodic watcher to trigger \*(L"in 10 |
|
|
2336 | seconds\*(R" (by specifying e.g. \f(CW\*(C`ev_now () + 10.\*(C'\fR, that is, an absolute time |
|
|
2337 | not a delay) and then reset your system clock to January of the previous |
|
|
2338 | year, then it will take a year or more to trigger the event (unlike an |
|
|
2339 | \&\f(CW\*(C`ev_timer\*(C'\fR, which would still trigger roughly 10 seconds after starting |
|
|
2340 | it, as it uses a relative timeout). |
|
|
2341 | .PP |
1757 | \&\f(CW\*(C`ev_periodic\*(C'\fRs can also be used to implement vastly more complex timers, |
2342 | \&\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 |
2343 | timers, such as triggering an event on each \*(L"midnight, local time\*(R", or |
1759 | complicated rules. |
2344 | other complicated rules. This cannot be done with \f(CW\*(C`ev_timer\*(C'\fR watchers, as |
|
|
2345 | those cannot react to time jumps. |
1760 | .PP |
2346 | .PP |
1761 | As with timers, the callback is guaranteed to be invoked only when the |
2347 | 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 |
2348 | 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. |
2349 | timers become ready during the same loop iteration then the ones with |
|
|
2350 | earlier time-out values are invoked before ones with later time-out values |
|
|
2351 | (but this is no longer true when a callback calls \f(CW\*(C`ev_run\*(C'\fR recursively). |
1764 | .PP |
2352 | .PP |
1765 | \fIWatcher-Specific Functions and Data Members\fR |
2353 | \fIWatcher-Specific Functions and Data Members\fR |
1766 | .IX Subsection "Watcher-Specific Functions and Data Members" |
2354 | .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 |
2355 | .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)" |
2356 | .IX Item "ev_periodic_init (ev_periodic *, callback, ev_tstamp offset, ev_tstamp interval, reschedule_cb)" |
1769 | .PD 0 |
2357 | .PD 0 |
1770 | .IP "ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)" 4 |
2358 | .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)" |
2359 | .IX Item "ev_periodic_set (ev_periodic *, ev_tstamp offset, ev_tstamp interval, reschedule_cb)" |
1772 | .PD |
2360 | .PD |
1773 | Lots of arguments, lets sort it out... There are basically three modes of |
2361 | 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: |
2362 | operation, and we will explain them from simplest to most complex: |
1775 | .RS 4 |
2363 | .RS 4 |
1776 | .IP "\(bu" 4 |
2364 | .IP "\(bu" 4 |
1777 | absolute timer (at = time, interval = reschedule_cb = 0) |
2365 | absolute timer (offset = absolute time, interval = 0, reschedule_cb = 0) |
1778 | .Sp |
2366 | .Sp |
1779 | In this configuration the watcher triggers an event after the wall clock |
2367 | 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 |
2368 | 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 |
2369 | 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. |
2370 | will be stopped and invoked when the system clock reaches or surpasses |
|
|
2371 | this point in time. |
1783 | .IP "\(bu" 4 |
2372 | .IP "\(bu" 4 |
1784 | repeating interval timer (at = offset, interval > 0, reschedule_cb = 0) |
2373 | repeating interval timer (offset = offset within interval, interval > 0, reschedule_cb = 0) |
1785 | .Sp |
2374 | .Sp |
1786 | In this mode the watcher will always be scheduled to time out at the next |
2375 | 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) |
2376 | \&\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. |
2377 | negative) and then repeat, regardless of any time jumps. The \f(CW\*(C`offset\*(C'\fR |
|
|
2378 | argument is merely an offset into the \f(CW\*(C`interval\*(C'\fR periods. |
1789 | .Sp |
2379 | .Sp |
1790 | This can be used to create timers that do not drift with respect to the |
2380 | 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 |
2381 | system clock, for example, here is an \f(CW\*(C`ev_periodic\*(C'\fR that triggers each |
1792 | hour, on the hour: |
2382 | hour, on the hour (with respect to \s-1UTC\s0): |
1793 | .Sp |
2383 | .Sp |
1794 | .Vb 1 |
2384 | .Vb 1 |
1795 | \& ev_periodic_set (&periodic, 0., 3600., 0); |
2385 | \& ev_periodic_set (&periodic, 0., 3600., 0); |
1796 | .Ve |
2386 | .Ve |
1797 | .Sp |
2387 | .Sp |
… | |
… | |
1800 | full hour (\s-1UTC\s0), or more correctly, when the system time is evenly divisible |
2390 | full hour (\s-1UTC\s0), or more correctly, when the system time is evenly divisible |
1801 | by 3600. |
2391 | by 3600. |
1802 | .Sp |
2392 | .Sp |
1803 | Another way to think about it (for the mathematically inclined) is that |
2393 | 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 |
2394 | \&\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. |
2395 | time where \f(CW\*(C`time = offset (mod interval)\*(C'\fR, regardless of any time jumps. |
1806 | .Sp |
2396 | .Sp |
1807 | For numerical stability it is preferable that the \f(CW\*(C`at\*(C'\fR value is near |
2397 | The \f(CW\*(C`interval\*(C'\fR \fI\s-1MUST\s0\fR be positive, and for numerical stability, the |
1808 | \&\f(CW\*(C`ev_now ()\*(C'\fR (the current time), but there is no range requirement for |
2398 | interval value should be higher than \f(CW\*(C`1/8192\*(C'\fR (which is around 100 |
1809 | this value, and in fact is often specified as zero. |
2399 | microseconds) and \f(CW\*(C`offset\*(C'\fR should be higher than \f(CW0\fR and should have |
|
|
2400 | at most a similar magnitude as the current time (say, within a factor of |
|
|
2401 | ten). Typical values for offset are, in fact, \f(CW0\fR or something between |
|
|
2402 | \&\f(CW0\fR and \f(CW\*(C`interval\*(C'\fR, which is also the recommended range. |
1810 | .Sp |
2403 | .Sp |
1811 | Note also that there is an upper limit to how often a timer can fire (\s-1CPU\s0 |
2404 | 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 |
2405 | 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 |
2406 | 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). |
2407 | millisecond (if the \s-1OS\s0 supports it and the machine is fast enough). |
1815 | .IP "\(bu" 4 |
2408 | .IP "\(bu" 4 |
1816 | manual reschedule mode (at and interval ignored, reschedule_cb = callback) |
2409 | manual reschedule mode (offset ignored, interval ignored, reschedule_cb = callback) |
1817 | .Sp |
2410 | .Sp |
1818 | In this mode the values for \f(CW\*(C`interval\*(C'\fR and \f(CW\*(C`at\*(C'\fR are both being |
2411 | 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 |
2412 | ignored. Instead, each time the periodic watcher gets scheduled, the |
1820 | reschedule callback will be called with the watcher as first, and the |
2413 | reschedule callback will be called with the watcher as first, and the |
1821 | current time as second argument. |
2414 | current time as second argument. |
1822 | .Sp |
2415 | .Sp |
1823 | \&\s-1NOTE:\s0 \fIThis callback \s-1MUST\s0 \s-1NOT\s0 stop or destroy any periodic watcher, |
2416 | \&\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. |
2417 | or make \s-1ANY\s0 other event loop modifications whatsoever, unless explicitly |
|
|
2418 | allowed by documentation here\fR. |
1825 | .Sp |
2419 | .Sp |
1826 | If you need to stop it, return \f(CW\*(C`now + 1e30\*(C'\fR (or so, fudge fudge) and stop |
2420 | 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 |
2421 | 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). |
2422 | only event loop modification you are allowed to do). |
1829 | .Sp |
2423 | .Sp |
… | |
… | |
1860 | when you changed some parameters or the reschedule callback would return |
2454 | 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 |
2455 | a different time than the last time it was called (e.g. in a crond like |
1862 | program when the crontabs have changed). |
2456 | program when the crontabs have changed). |
1863 | .IP "ev_tstamp ev_periodic_at (ev_periodic *)" 4 |
2457 | .IP "ev_tstamp ev_periodic_at (ev_periodic *)" 4 |
1864 | .IX Item "ev_tstamp ev_periodic_at (ev_periodic *)" |
2458 | .IX Item "ev_tstamp ev_periodic_at (ev_periodic *)" |
1865 | When active, returns the absolute time that the watcher is supposed to |
2459 | When active, returns the absolute time that the watcher is supposed |
1866 | trigger next. |
2460 | to trigger next. This is not the same as the \f(CW\*(C`offset\*(C'\fR argument to |
|
|
2461 | \&\f(CW\*(C`ev_periodic_set\*(C'\fR, but indeed works even in interval and manual |
|
|
2462 | rescheduling modes. |
1867 | .IP "ev_tstamp offset [read\-write]" 4 |
2463 | .IP "ev_tstamp offset [read\-write]" 4 |
1868 | .IX Item "ev_tstamp offset [read-write]" |
2464 | .IX Item "ev_tstamp offset [read-write]" |
1869 | When repeating, this contains the offset value, otherwise this is the |
2465 | 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). |
2466 | absolute point in time (the \f(CW\*(C`offset\*(C'\fR value passed to \f(CW\*(C`ev_periodic_set\*(C'\fR, |
|
|
2467 | although libev might modify this value for better numerical stability). |
1871 | .Sp |
2468 | .Sp |
1872 | Can be modified any time, but changes only take effect when the periodic |
2469 | 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. |
2470 | timer fires or \f(CW\*(C`ev_periodic_again\*(C'\fR is being called. |
1874 | .IP "ev_tstamp interval [read\-write]" 4 |
2471 | .IP "ev_tstamp interval [read\-write]" 4 |
1875 | .IX Item "ev_tstamp interval [read-write]" |
2472 | .IX Item "ev_tstamp interval [read-write]" |
… | |
… | |
1889 | system time is divisible by 3600. The callback invocation times have |
2486 | system time is divisible by 3600. The callback invocation times have |
1890 | potentially a lot of jitter, but good long-term stability. |
2487 | potentially a lot of jitter, but good long-term stability. |
1891 | .PP |
2488 | .PP |
1892 | .Vb 5 |
2489 | .Vb 5 |
1893 | \& static void |
2490 | \& static void |
1894 | \& clock_cb (struct ev_loop *loop, ev_io *w, int revents) |
2491 | \& clock_cb (struct ev_loop *loop, ev_periodic *w, int revents) |
1895 | \& { |
2492 | \& { |
1896 | \& ... its now a full hour (UTC, or TAI or whatever your clock follows) |
2493 | \& ... its now a full hour (UTC, or TAI or whatever your clock follows) |
1897 | \& } |
2494 | \& } |
1898 | \& |
2495 | \& |
1899 | \& ev_periodic hourly_tick; |
2496 | \& ev_periodic hourly_tick; |
… | |
… | |
1921 | \& ev_periodic hourly_tick; |
2518 | \& ev_periodic hourly_tick; |
1922 | \& ev_periodic_init (&hourly_tick, clock_cb, |
2519 | \& ev_periodic_init (&hourly_tick, clock_cb, |
1923 | \& fmod (ev_now (loop), 3600.), 3600., 0); |
2520 | \& fmod (ev_now (loop), 3600.), 3600., 0); |
1924 | \& ev_periodic_start (loop, &hourly_tick); |
2521 | \& ev_periodic_start (loop, &hourly_tick); |
1925 | .Ve |
2522 | .Ve |
1926 | .ie n .Sh """ev_signal"" \- signal me when a signal gets signalled!" |
2523 | .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!" |
2524 | .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!" |
2525 | .IX Subsection "ev_signal - signal me when a signal gets signalled!" |
1929 | Signal watchers will trigger an event when the process receives a specific |
2526 | 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 |
2527 | 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 |
2528 | will try its best to deliver signals synchronously, i.e. as part of the |
1932 | normal event processing, like any other event. |
2529 | normal event processing, like any other event. |
1933 | .PP |
2530 | .PP |
1934 | If you want signals asynchronously, just use \f(CW\*(C`sigaction\*(C'\fR as you would |
2531 | 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 |
2532 | \&\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. |
2533 | the signal. You can even use \f(CW\*(C`ev_async\*(C'\fR from a signal handler to |
|
|
2534 | synchronously wake up an event loop. |
1937 | .PP |
2535 | .PP |
1938 | You can configure as many watchers as you like per signal. Only when the |
2536 | You can configure as many watchers as you like for the same signal, but |
|
|
2537 | only within the same loop, i.e. you can watch for \f(CW\*(C`SIGINT\*(C'\fR in your |
|
|
2538 | default loop and for \f(CW\*(C`SIGIO\*(C'\fR in another loop, but you cannot watch for |
|
|
2539 | \&\f(CW\*(C`SIGINT\*(C'\fR in both the default loop and another loop at the same time. At |
|
|
2540 | the moment, \f(CW\*(C`SIGCHLD\*(C'\fR is permanently tied to the default loop. |
|
|
2541 | .PP |
1939 | first watcher gets started will libev actually register a signal handler |
2542 | 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 |
2543 | 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 |
2544 | 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 |
2545 | .PP |
1945 | If possible and supported, libev will install its handlers with |
2546 | 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 |
2547 | \&\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 |
2548 | 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 |
2549 | 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. |
2550 | and unblock them in an \f(CW\*(C`ev_prepare\*(C'\fR watcher. |
|
|
2551 | .PP |
|
|
2552 | \fIThe special problem of inheritance over fork/execve/pthread_create\fR |
|
|
2553 | .IX Subsection "The special problem of inheritance over fork/execve/pthread_create" |
|
|
2554 | .PP |
|
|
2555 | Both the signal mask (\f(CW\*(C`sigprocmask\*(C'\fR) and the signal disposition |
|
|
2556 | (\f(CW\*(C`sigaction\*(C'\fR) are unspecified after starting a signal watcher (and after |
|
|
2557 | stopping it again), that is, libev might or might not block the signal, |
|
|
2558 | and might or might not set or restore the installed signal handler (but |
|
|
2559 | see \f(CW\*(C`EVFLAG_NOSIGMASK\*(C'\fR). |
|
|
2560 | .PP |
|
|
2561 | While this does not matter for the signal disposition (libev never |
|
|
2562 | sets signals to \f(CW\*(C`SIG_IGN\*(C'\fR, so handlers will be reset to \f(CW\*(C`SIG_DFL\*(C'\fR on |
|
|
2563 | \&\f(CW\*(C`execve\*(C'\fR), this matters for the signal mask: many programs do not expect |
|
|
2564 | certain signals to be blocked. |
|
|
2565 | .PP |
|
|
2566 | This means that before calling \f(CW\*(C`exec\*(C'\fR (from the child) you should reset |
|
|
2567 | the signal mask to whatever \*(L"default\*(R" you expect (all clear is a good |
|
|
2568 | choice usually). |
|
|
2569 | .PP |
|
|
2570 | The simplest way to ensure that the signal mask is reset in the child is |
|
|
2571 | to install a fork handler with \f(CW\*(C`pthread_atfork\*(C'\fR that resets it. That will |
|
|
2572 | catch fork calls done by libraries (such as the libc) as well. |
|
|
2573 | .PP |
|
|
2574 | In current versions of libev, the signal will not be blocked indefinitely |
|
|
2575 | unless you use the \f(CW\*(C`signalfd\*(C'\fR \s-1API\s0 (\f(CW\*(C`EV_SIGNALFD\*(C'\fR). While this reduces |
|
|
2576 | the window of opportunity for problems, it will not go away, as libev |
|
|
2577 | \&\fIhas\fR to modify the signal mask, at least temporarily. |
|
|
2578 | .PP |
|
|
2579 | So I can't stress this enough: \fIIf you do not reset your signal mask when |
|
|
2580 | you expect it to be empty, you have a race condition in your code\fR. This |
|
|
2581 | is not a libev-specific thing, this is true for most event libraries. |
|
|
2582 | .PP |
|
|
2583 | \fIThe special problem of threads signal handling\fR |
|
|
2584 | .IX Subsection "The special problem of threads signal handling" |
|
|
2585 | .PP |
|
|
2586 | \&\s-1POSIX\s0 threads has problematic signal handling semantics, specifically, |
|
|
2587 | a lot of functionality (sigfd, sigwait etc.) only really works if all |
|
|
2588 | threads in a process block signals, which is hard to achieve. |
|
|
2589 | .PP |
|
|
2590 | When you want to use sigwait (or mix libev signal handling with your own |
|
|
2591 | for the same signals), you can tackle this problem by globally blocking |
|
|
2592 | all signals before creating any threads (or creating them with a fully set |
|
|
2593 | sigprocmask) and also specifying the \f(CW\*(C`EVFLAG_NOSIGMASK\*(C'\fR when creating |
|
|
2594 | loops. Then designate one thread as \*(L"signal receiver thread\*(R" which handles |
|
|
2595 | these signals. You can pass on any signals that libev might be interested |
|
|
2596 | in by calling \f(CW\*(C`ev_feed_signal\*(C'\fR. |
1950 | .PP |
2597 | .PP |
1951 | \fIWatcher-Specific Functions and Data Members\fR |
2598 | \fIWatcher-Specific Functions and Data Members\fR |
1952 | .IX Subsection "Watcher-Specific Functions and Data Members" |
2599 | .IX Subsection "Watcher-Specific Functions and Data Members" |
1953 | .IP "ev_signal_init (ev_signal *, callback, int signum)" 4 |
2600 | .IP "ev_signal_init (ev_signal *, callback, int signum)" 4 |
1954 | .IX Item "ev_signal_init (ev_signal *, callback, int signum)" |
2601 | .IX Item "ev_signal_init (ev_signal *, callback, int signum)" |
… | |
… | |
1969 | .PP |
2616 | .PP |
1970 | .Vb 5 |
2617 | .Vb 5 |
1971 | \& static void |
2618 | \& static void |
1972 | \& sigint_cb (struct ev_loop *loop, ev_signal *w, int revents) |
2619 | \& sigint_cb (struct ev_loop *loop, ev_signal *w, int revents) |
1973 | \& { |
2620 | \& { |
1974 | \& ev_unloop (loop, EVUNLOOP_ALL); |
2621 | \& ev_break (loop, EVBREAK_ALL); |
1975 | \& } |
2622 | \& } |
1976 | \& |
2623 | \& |
1977 | \& ev_signal signal_watcher; |
2624 | \& ev_signal signal_watcher; |
1978 | \& ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
2625 | \& ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
1979 | \& ev_signal_start (loop, &signal_watcher); |
2626 | \& ev_signal_start (loop, &signal_watcher); |
1980 | .Ve |
2627 | .Ve |
1981 | .ie n .Sh """ev_child"" \- watch out for process status changes" |
2628 | .ie n .SS """ev_child"" \- watch out for process status changes" |
1982 | .el .Sh "\f(CWev_child\fP \- watch out for process status changes" |
2629 | .el .SS "\f(CWev_child\fP \- watch out for process status changes" |
1983 | .IX Subsection "ev_child - watch out for process status changes" |
2630 | .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 |
2631 | 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 |
2632 | 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 |
2633 | 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 |
2634 | 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., |
2635 | 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, |
2636 | 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 |
2637 | but forking and registering a watcher a few event loop iterations later or |
1991 | not. |
2638 | in the next callback invocation is not. |
1992 | .PP |
2639 | .PP |
1993 | Only the default event loop is capable of handling signals, and therefore |
2640 | Only the default event loop is capable of handling signals, and therefore |
1994 | you can only register child watchers in the default event loop. |
2641 | you can only register child watchers in the default event loop. |
1995 | .PP |
2642 | .PP |
|
|
2643 | Due to some design glitches inside libev, child watchers will always be |
|
|
2644 | handled at maximum priority (their priority is set to \f(CW\*(C`EV_MAXPRI\*(C'\fR by |
|
|
2645 | libev) |
|
|
2646 | .PP |
1996 | \fIProcess Interaction\fR |
2647 | \fIProcess Interaction\fR |
1997 | .IX Subsection "Process Interaction" |
2648 | .IX Subsection "Process Interaction" |
1998 | .PP |
2649 | .PP |
1999 | Libev grabs \f(CW\*(C`SIGCHLD\*(C'\fR as soon as the default event loop is |
2650 | 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 |
2651 | initialised. This is necessary to guarantee proper behaviour even if the |
2001 | the first child watcher is started after the child exits. The occurrence |
2652 | 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 |
2653 | 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 |
2654 | synchronously as part of the event loop processing. Libev always reaps all |
2004 | children, even ones not watched. |
2655 | children, even ones not watched. |
2005 | .PP |
2656 | .PP |
2006 | \fIOverriding the Built-In Processing\fR |
2657 | \fIOverriding the Built-In Processing\fR |
… | |
… | |
2018 | .IX Subsection "Stopping the Child Watcher" |
2669 | .IX Subsection "Stopping the Child Watcher" |
2019 | .PP |
2670 | .PP |
2020 | Currently, the child watcher never gets stopped, even when the |
2671 | Currently, the child watcher never gets stopped, even when the |
2021 | child terminates, so normally one needs to stop the watcher in the |
2672 | child terminates, so normally one needs to stop the watcher in the |
2022 | callback. Future versions of libev might stop the watcher automatically |
2673 | callback. Future versions of libev might stop the watcher automatically |
2023 | when a child exit is detected. |
2674 | when a child exit is detected (calling \f(CW\*(C`ev_child_stop\*(C'\fR twice is not a |
|
|
2675 | problem). |
2024 | .PP |
2676 | .PP |
2025 | \fIWatcher-Specific Functions and Data Members\fR |
2677 | \fIWatcher-Specific Functions and Data Members\fR |
2026 | .IX Subsection "Watcher-Specific Functions and Data Members" |
2678 | .IX Subsection "Watcher-Specific Functions and Data Members" |
2027 | .IP "ev_child_init (ev_child *, callback, int pid, int trace)" 4 |
2679 | .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)" |
2680 | .IX Item "ev_child_init (ev_child *, callback, int pid, int trace)" |
… | |
… | |
2078 | \& { |
2730 | \& { |
2079 | \& ev_child_init (&cw, child_cb, pid, 0); |
2731 | \& ev_child_init (&cw, child_cb, pid, 0); |
2080 | \& ev_child_start (EV_DEFAULT_ &cw); |
2732 | \& ev_child_start (EV_DEFAULT_ &cw); |
2081 | \& } |
2733 | \& } |
2082 | .Ve |
2734 | .Ve |
2083 | .ie n .Sh """ev_stat"" \- did the file attributes just change?" |
2735 | .ie n .SS """ev_stat"" \- did the file attributes just change?" |
2084 | .el .Sh "\f(CWev_stat\fP \- did the file attributes just change?" |
2736 | .el .SS "\f(CWev_stat\fP \- did the file attributes just change?" |
2085 | .IX Subsection "ev_stat - did the file attributes just change?" |
2737 | .IX Subsection "ev_stat - did the file attributes just change?" |
2086 | This watches a file system path for attribute changes. That is, it calls |
2738 | 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) |
2739 | \&\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 |
2740 | and sees if it changed compared to the last time, invoking the callback if |
2089 | it did. |
2741 | it did. |
… | |
… | |
2303 | \& ... |
2955 | \& ... |
2304 | \& ev_stat_init (&passwd, stat_cb, "/etc/passwd", 0.); |
2956 | \& ev_stat_init (&passwd, stat_cb, "/etc/passwd", 0.); |
2305 | \& ev_stat_start (loop, &passwd); |
2957 | \& ev_stat_start (loop, &passwd); |
2306 | \& ev_timer_init (&timer, timer_cb, 0., 1.02); |
2958 | \& ev_timer_init (&timer, timer_cb, 0., 1.02); |
2307 | .Ve |
2959 | .Ve |
2308 | .ie n .Sh """ev_idle"" \- when you've got nothing better to do..." |
2960 | .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..." |
2961 | .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..." |
2962 | .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 |
2963 | 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 |
2964 | priority are pending (prepare, check and other idle watchers do not count |
2313 | as receiving \*(L"events\*(R"). |
2965 | as receiving \*(L"events\*(R"). |
2314 | .PP |
2966 | .PP |
… | |
… | |
2327 | \&\*(L"pseudo-background processing\*(R", or delay processing stuff to after the |
2979 | \&\*(L"pseudo-background processing\*(R", or delay processing stuff to after the |
2328 | event loop has handled all outstanding events. |
2980 | event loop has handled all outstanding events. |
2329 | .PP |
2981 | .PP |
2330 | \fIWatcher-Specific Functions and Data Members\fR |
2982 | \fIWatcher-Specific Functions and Data Members\fR |
2331 | .IX Subsection "Watcher-Specific Functions and Data Members" |
2983 | .IX Subsection "Watcher-Specific Functions and Data Members" |
2332 | .IP "ev_idle_init (ev_signal *, callback)" 4 |
2984 | .IP "ev_idle_init (ev_idle *, callback)" 4 |
2333 | .IX Item "ev_idle_init (ev_signal *, callback)" |
2985 | .IX Item "ev_idle_init (ev_idle *, callback)" |
2334 | Initialises and configures the idle watcher \- it has no parameters of any |
2986 | 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, |
2987 | kind. There is a \f(CW\*(C`ev_idle_set\*(C'\fR macro, but using it is utterly pointless, |
2336 | believe me. |
2988 | believe me. |
2337 | .PP |
2989 | .PP |
2338 | \fIExamples\fR |
2990 | \fIExamples\fR |
… | |
… | |
2350 | \& // no longer anything immediate to do. |
3002 | \& // no longer anything immediate to do. |
2351 | \& } |
3003 | \& } |
2352 | \& |
3004 | \& |
2353 | \& ev_idle *idle_watcher = malloc (sizeof (ev_idle)); |
3005 | \& ev_idle *idle_watcher = malloc (sizeof (ev_idle)); |
2354 | \& ev_idle_init (idle_watcher, idle_cb); |
3006 | \& ev_idle_init (idle_watcher, idle_cb); |
2355 | \& ev_idle_start (loop, idle_cb); |
3007 | \& ev_idle_start (loop, idle_watcher); |
2356 | .Ve |
3008 | .Ve |
2357 | .ie n .Sh """ev_prepare""\fP and \f(CW""ev_check"" \- customise your event loop!" |
3009 | .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!" |
3010 | .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!" |
3011 | .IX Subsection "ev_prepare and ev_check - customise your event loop!" |
2360 | Prepare and check watchers are usually (but not always) used in pairs: |
3012 | Prepare and check watchers are usually (but not always) used in pairs: |
2361 | prepare watchers get invoked before the process blocks and check watchers |
3013 | prepare watchers get invoked before the process blocks and check watchers |
2362 | afterwards. |
3014 | afterwards. |
2363 | .PP |
3015 | .PP |
2364 | You \fImust not\fR call \f(CW\*(C`ev_loop\*(C'\fR or similar functions that enter |
3016 | 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 |
3017 | 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 |
3018 | 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 |
3019 | 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, |
3020 | 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 |
3021 | \&\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]; |
3105 | \& struct pollfd fds [nfd]; |
2454 | \& // actual code will need to loop here and realloc etc. |
3106 | \& // actual code will need to loop here and realloc etc. |
2455 | \& adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
3107 | \& adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
2456 | \& |
3108 | \& |
2457 | \& /* the callback is illegal, but won\*(Aqt be called as we stop during check */ |
3109 | \& /* the callback is illegal, but won\*(Aqt be called as we stop during check */ |
2458 | \& ev_timer_init (&tw, 0, timeout * 1e\-3); |
3110 | \& ev_timer_init (&tw, 0, timeout * 1e\-3, 0.); |
2459 | \& ev_timer_start (loop, &tw); |
3111 | \& ev_timer_start (loop, &tw); |
2460 | \& |
3112 | \& |
2461 | \& // create one ev_io per pollfd |
3113 | \& // create one ev_io per pollfd |
2462 | \& for (int i = 0; i < nfd; ++i) |
3114 | \& for (int i = 0; i < nfd; ++i) |
2463 | \& { |
3115 | \& { |
… | |
… | |
2541 | \& |
3193 | \& |
2542 | \& if (timeout >= 0) |
3194 | \& if (timeout >= 0) |
2543 | \& // create/start timer |
3195 | \& // create/start timer |
2544 | \& |
3196 | \& |
2545 | \& // poll |
3197 | \& // poll |
2546 | \& ev_loop (EV_A_ 0); |
3198 | \& ev_run (EV_A_ 0); |
2547 | \& |
3199 | \& |
2548 | \& // stop timer again |
3200 | \& // stop timer again |
2549 | \& if (timeout >= 0) |
3201 | \& if (timeout >= 0) |
2550 | \& ev_timer_stop (EV_A_ &to); |
3202 | \& ev_timer_stop (EV_A_ &to); |
2551 | \& |
3203 | \& |
… | |
… | |
2554 | \& ev_io_stop (EV_A_ iow [n]); |
3206 | \& ev_io_stop (EV_A_ iow [n]); |
2555 | \& |
3207 | \& |
2556 | \& return got_events; |
3208 | \& return got_events; |
2557 | \& } |
3209 | \& } |
2558 | .Ve |
3210 | .Ve |
2559 | .ie n .Sh """ev_embed"" \- when one backend isn't enough..." |
3211 | .ie n .SS """ev_embed"" \- when one backend isn't enough..." |
2560 | .el .Sh "\f(CWev_embed\fP \- when one backend isn't enough..." |
3212 | .el .SS "\f(CWev_embed\fP \- when one backend isn't enough..." |
2561 | .IX Subsection "ev_embed - when one backend isn't enough..." |
3213 | .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 |
3214 | 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 |
3215 | 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 |
3216 | loop, other types of watchers might be handled in a delayed or incorrect |
2565 | fashion and must not be used). |
3217 | fashion and must not be used). |
… | |
… | |
2629 | to invoke it (it will continue to be called until the sweep has been done, |
3281 | to invoke it (it will continue to be called until the sweep has been done, |
2630 | if you do not want that, you need to temporarily stop the embed watcher). |
3282 | if you do not want that, you need to temporarily stop the embed watcher). |
2631 | .IP "ev_embed_sweep (loop, ev_embed *)" 4 |
3283 | .IP "ev_embed_sweep (loop, ev_embed *)" 4 |
2632 | .IX Item "ev_embed_sweep (loop, ev_embed *)" |
3284 | .IX Item "ev_embed_sweep (loop, ev_embed *)" |
2633 | Make a single, non-blocking sweep over the embedded loop. This works |
3285 | Make a single, non-blocking sweep over the embedded loop. This works |
2634 | similarly to \f(CW\*(C`ev_loop (embedded_loop, EVLOOP_NONBLOCK)\*(C'\fR, but in the most |
3286 | similarly to \f(CW\*(C`ev_run (embedded_loop, EVRUN_NOWAIT)\*(C'\fR, but in the most |
2635 | appropriate way for embedded loops. |
3287 | appropriate way for embedded loops. |
2636 | .IP "struct ev_loop *other [read\-only]" 4 |
3288 | .IP "struct ev_loop *other [read\-only]" 4 |
2637 | .IX Item "struct ev_loop *other [read-only]" |
3289 | .IX Item "struct ev_loop *other [read-only]" |
2638 | The embedded event loop. |
3290 | The embedded event loop. |
2639 | .PP |
3291 | .PP |
… | |
… | |
2687 | \& if (!loop_socket) |
3339 | \& if (!loop_socket) |
2688 | \& loop_socket = loop; |
3340 | \& loop_socket = loop; |
2689 | \& |
3341 | \& |
2690 | \& // now use loop_socket for all sockets, and loop for everything else |
3342 | \& // now use loop_socket for all sockets, and loop for everything else |
2691 | .Ve |
3343 | .Ve |
2692 | .ie n .Sh """ev_fork"" \- the audacity to resume the event loop after a fork" |
3344 | .ie n .SS """ev_fork"" \- the audacity to resume the event loop after a fork" |
2693 | .el .Sh "\f(CWev_fork\fP \- the audacity to resume the event loop after a fork" |
3345 | .el .SS "\f(CWev_fork\fP \- the audacity to resume the event loop after a fork" |
2694 | .IX Subsection "ev_fork - the audacity to resume the event loop after a fork" |
3346 | .IX Subsection "ev_fork - the audacity to resume the event loop after a fork" |
2695 | Fork watchers are called when a \f(CW\*(C`fork ()\*(C'\fR was detected (usually because |
3347 | Fork watchers are called when a \f(CW\*(C`fork ()\*(C'\fR was detected (usually because |
2696 | whoever is a good citizen cared to tell libev about it by calling |
3348 | whoever is a good citizen cared to tell libev about it by calling |
2697 | \&\f(CW\*(C`ev_default_fork\*(C'\fR or \f(CW\*(C`ev_loop_fork\*(C'\fR). The invocation is done before the |
3349 | \&\f(CW\*(C`ev_default_fork\*(C'\fR or \f(CW\*(C`ev_loop_fork\*(C'\fR). The invocation is done before the |
2698 | event loop blocks next and before \f(CW\*(C`ev_check\*(C'\fR watchers are being called, |
3350 | event loop blocks next and before \f(CW\*(C`ev_check\*(C'\fR watchers are being called, |
2699 | and only in the child after the fork. If whoever good citizen calling |
3351 | and only in the child after the fork. If whoever good citizen calling |
2700 | \&\f(CW\*(C`ev_default_fork\*(C'\fR cheats and calls it in the wrong process, the fork |
3352 | \&\f(CW\*(C`ev_default_fork\*(C'\fR cheats and calls it in the wrong process, the fork |
2701 | handlers will be invoked, too, of course. |
3353 | handlers will be invoked, too, of course. |
2702 | .PP |
3354 | .PP |
|
|
3355 | \fIThe special problem of life after fork \- how is it possible?\fR |
|
|
3356 | .IX Subsection "The special problem of life after fork - how is it possible?" |
|
|
3357 | .PP |
|
|
3358 | Most uses of \f(CW\*(C`fork()\*(C'\fR consist of forking, then some simple calls to set |
|
|
3359 | up/change the process environment, followed by a call to \f(CW\*(C`exec()\*(C'\fR. This |
|
|
3360 | sequence should be handled by libev without any problems. |
|
|
3361 | .PP |
|
|
3362 | This changes when the application actually wants to do event handling |
|
|
3363 | in the child, or both parent in child, in effect \*(L"continuing\*(R" after the |
|
|
3364 | fork. |
|
|
3365 | .PP |
|
|
3366 | The default mode of operation (for libev, with application help to detect |
|
|
3367 | forks) is to duplicate all the state in the child, as would be expected |
|
|
3368 | when \fIeither\fR the parent \fIor\fR the child process continues. |
|
|
3369 | .PP |
|
|
3370 | When both processes want to continue using libev, then this is usually the |
|
|
3371 | wrong result. In that case, usually one process (typically the parent) is |
|
|
3372 | supposed to continue with all watchers in place as before, while the other |
|
|
3373 | process typically wants to start fresh, i.e. without any active watchers. |
|
|
3374 | .PP |
|
|
3375 | The cleanest and most efficient way to achieve that with libev is to |
|
|
3376 | simply create a new event loop, which of course will be \*(L"empty\*(R", and |
|
|
3377 | use that for new watchers. This has the advantage of not touching more |
|
|
3378 | memory than necessary, and thus avoiding the copy-on-write, and the |
|
|
3379 | disadvantage of having to use multiple event loops (which do not support |
|
|
3380 | signal watchers). |
|
|
3381 | .PP |
|
|
3382 | When this is not possible, or you want to use the default loop for |
|
|
3383 | other reasons, then in the process that wants to start \*(L"fresh\*(R", call |
|
|
3384 | \&\f(CW\*(C`ev_loop_destroy (EV_DEFAULT)\*(C'\fR followed by \f(CW\*(C`ev_default_loop (...)\*(C'\fR. |
|
|
3385 | Destroying the default loop will \*(L"orphan\*(R" (not stop) all registered |
|
|
3386 | watchers, so you have to be careful not to execute code that modifies |
|
|
3387 | those watchers. Note also that in that case, you have to re-register any |
|
|
3388 | signal watchers. |
|
|
3389 | .PP |
2703 | \fIWatcher-Specific Functions and Data Members\fR |
3390 | \fIWatcher-Specific Functions and Data Members\fR |
2704 | .IX Subsection "Watcher-Specific Functions and Data Members" |
3391 | .IX Subsection "Watcher-Specific Functions and Data Members" |
2705 | .IP "ev_fork_init (ev_signal *, callback)" 4 |
3392 | .IP "ev_fork_init (ev_fork *, callback)" 4 |
2706 | .IX Item "ev_fork_init (ev_signal *, callback)" |
3393 | .IX Item "ev_fork_init (ev_fork *, callback)" |
2707 | Initialises and configures the fork watcher \- it has no parameters of any |
3394 | Initialises and configures the fork watcher \- it has no parameters of any |
2708 | kind. There is a \f(CW\*(C`ev_fork_set\*(C'\fR macro, but using it is utterly pointless, |
3395 | kind. There is a \f(CW\*(C`ev_fork_set\*(C'\fR macro, but using it is utterly pointless, |
2709 | believe me. |
3396 | really. |
|
|
3397 | .ie n .SS """ev_cleanup"" \- even the best things end" |
|
|
3398 | .el .SS "\f(CWev_cleanup\fP \- even the best things end" |
|
|
3399 | .IX Subsection "ev_cleanup - even the best things end" |
|
|
3400 | Cleanup watchers are called just before the event loop is being destroyed |
|
|
3401 | by a call to \f(CW\*(C`ev_loop_destroy\*(C'\fR. |
|
|
3402 | .PP |
|
|
3403 | While there is no guarantee that the event loop gets destroyed, cleanup |
|
|
3404 | watchers provide a convenient method to install cleanup hooks for your |
|
|
3405 | program, worker threads and so on \- you just to make sure to destroy the |
|
|
3406 | loop when you want them to be invoked. |
|
|
3407 | .PP |
|
|
3408 | Cleanup watchers are invoked in the same way as any other watcher. Unlike |
|
|
3409 | all other watchers, they do not keep a reference to the event loop (which |
|
|
3410 | makes a lot of sense if you think about it). Like all other watchers, you |
|
|
3411 | can call libev functions in the callback, except \f(CW\*(C`ev_cleanup_start\*(C'\fR. |
|
|
3412 | .PP |
|
|
3413 | \fIWatcher-Specific Functions and Data Members\fR |
|
|
3414 | .IX Subsection "Watcher-Specific Functions and Data Members" |
|
|
3415 | .IP "ev_cleanup_init (ev_cleanup *, callback)" 4 |
|
|
3416 | .IX Item "ev_cleanup_init (ev_cleanup *, callback)" |
|
|
3417 | Initialises and configures the cleanup watcher \- it has no parameters of |
|
|
3418 | any kind. There is a \f(CW\*(C`ev_cleanup_set\*(C'\fR macro, but using it is utterly |
|
|
3419 | pointless, I assure you. |
|
|
3420 | .PP |
|
|
3421 | Example: Register an atexit handler to destroy the default loop, so any |
|
|
3422 | cleanup functions are called. |
|
|
3423 | .PP |
|
|
3424 | .Vb 5 |
|
|
3425 | \& static void |
|
|
3426 | \& program_exits (void) |
|
|
3427 | \& { |
|
|
3428 | \& ev_loop_destroy (EV_DEFAULT_UC); |
|
|
3429 | \& } |
|
|
3430 | \& |
|
|
3431 | \& ... |
|
|
3432 | \& atexit (program_exits); |
|
|
3433 | .Ve |
2710 | .ie n .Sh """ev_async"" \- how to wake up another event loop" |
3434 | .ie n .SS """ev_async"" \- how to wake up an event loop" |
2711 | .el .Sh "\f(CWev_async\fP \- how to wake up another event loop" |
3435 | .el .SS "\f(CWev_async\fP \- how to wake up an event loop" |
2712 | .IX Subsection "ev_async - how to wake up another event loop" |
3436 | .IX Subsection "ev_async - how to wake up an event loop" |
2713 | In general, you cannot use an \f(CW\*(C`ev_loop\*(C'\fR from multiple threads or other |
3437 | In general, you cannot use an \f(CW\*(C`ev_loop\*(C'\fR from multiple threads or other |
2714 | asynchronous sources such as signal handlers (as opposed to multiple event |
3438 | asynchronous sources such as signal handlers (as opposed to multiple event |
2715 | loops \- those are of course safe to use in different threads). |
3439 | loops \- those are of course safe to use in different threads). |
2716 | .PP |
3440 | .PP |
2717 | Sometimes, however, you need to wake up another event loop you do not |
3441 | Sometimes, however, you need to wake up an event loop you do not control, |
2718 | control, for example because it belongs to another thread. This is what |
3442 | for example because it belongs to another thread. This is what \f(CW\*(C`ev_async\*(C'\fR |
2719 | \&\f(CW\*(C`ev_async\*(C'\fR watchers do: as long as the \f(CW\*(C`ev_async\*(C'\fR watcher is active, you |
3443 | watchers do: as long as the \f(CW\*(C`ev_async\*(C'\fR watcher is active, you can signal |
2720 | can signal it by calling \f(CW\*(C`ev_async_send\*(C'\fR, which is thread\- and signal |
3444 | it by calling \f(CW\*(C`ev_async_send\*(C'\fR, which is thread\- and signal safe. |
2721 | safe. |
|
|
2722 | .PP |
3445 | .PP |
2723 | This functionality is very similar to \f(CW\*(C`ev_signal\*(C'\fR watchers, as signals, |
3446 | This functionality is very similar to \f(CW\*(C`ev_signal\*(C'\fR watchers, as signals, |
2724 | too, are asynchronous in nature, and signals, too, will be compressed |
3447 | too, are asynchronous in nature, and signals, too, will be compressed |
2725 | (i.e. the number of callback invocations may be less than the number of |
3448 | (i.e. the number of callback invocations may be less than the number of |
2726 | \&\f(CW\*(C`ev_async_sent\*(C'\fR calls). |
3449 | \&\f(CW\*(C`ev_async_sent\*(C'\fR calls). In fact, you could use signal watchers as a kind |
2727 | .PP |
3450 | of \*(L"global async watchers\*(R" by using a watcher on an otherwise unused |
2728 | Unlike \f(CW\*(C`ev_signal\*(C'\fR watchers, \f(CW\*(C`ev_async\*(C'\fR works with any event loop, not |
3451 | signal, and \f(CW\*(C`ev_feed_signal\*(C'\fR to signal this watcher from another thread, |
2729 | just the default loop. |
3452 | even without knowing which loop owns the signal. |
2730 | .PP |
3453 | .PP |
2731 | \fIQueueing\fR |
3454 | \fIQueueing\fR |
2732 | .IX Subsection "Queueing" |
3455 | .IX Subsection "Queueing" |
2733 | .PP |
3456 | .PP |
2734 | \&\f(CW\*(C`ev_async\*(C'\fR does not support queueing of data in any way. The reason |
3457 | \&\f(CW\*(C`ev_async\*(C'\fR does not support queueing of data in any way. The reason |
2735 | is that the author does not know of a simple (or any) algorithm for a |
3458 | is that the author does not know of a simple (or any) algorithm for a |
2736 | multiple-writer-single-reader queue that works in all cases and doesn't |
3459 | multiple-writer-single-reader queue that works in all cases and doesn't |
2737 | need elaborate support such as pthreads. |
3460 | need elaborate support such as pthreads or unportable memory access |
|
|
3461 | semantics. |
2738 | .PP |
3462 | .PP |
2739 | That means that if you want to queue data, you have to provide your own |
3463 | That means that if you want to queue data, you have to provide your own |
2740 | queue. But at least I can tell you how to implement locking around your |
3464 | queue. But at least I can tell you how to implement locking around your |
2741 | queue: |
3465 | queue: |
2742 | .IP "queueing from a signal handler context" 4 |
3466 | .IP "queueing from a signal handler context" 4 |
… | |
… | |
2820 | kind. There is a \f(CW\*(C`ev_async_set\*(C'\fR macro, but using it is utterly pointless, |
3544 | kind. There is a \f(CW\*(C`ev_async_set\*(C'\fR macro, but using it is utterly pointless, |
2821 | trust me. |
3545 | trust me. |
2822 | .IP "ev_async_send (loop, ev_async *)" 4 |
3546 | .IP "ev_async_send (loop, ev_async *)" 4 |
2823 | .IX Item "ev_async_send (loop, ev_async *)" |
3547 | .IX Item "ev_async_send (loop, ev_async *)" |
2824 | Sends/signals/activates the given \f(CW\*(C`ev_async\*(C'\fR watcher, that is, feeds |
3548 | Sends/signals/activates the given \f(CW\*(C`ev_async\*(C'\fR watcher, that is, feeds |
2825 | an \f(CW\*(C`EV_ASYNC\*(C'\fR event on the watcher into the event loop. Unlike |
3549 | an \f(CW\*(C`EV_ASYNC\*(C'\fR event on the watcher into the event loop, and instantly |
|
|
3550 | returns. |
|
|
3551 | .Sp |
2826 | \&\f(CW\*(C`ev_feed_event\*(C'\fR, this call is safe to do from other threads, signal or |
3552 | Unlike \f(CW\*(C`ev_feed_event\*(C'\fR, this call is safe to do from other threads, |
2827 | similar contexts (see the discussion of \f(CW\*(C`EV_ATOMIC_T\*(C'\fR in the embedding |
3553 | signal or similar contexts (see the discussion of \f(CW\*(C`EV_ATOMIC_T\*(C'\fR in the |
2828 | section below on what exactly this means). |
3554 | embedding section below on what exactly this means). |
2829 | .Sp |
3555 | .Sp |
2830 | This call incurs the overhead of a system call only once per loop iteration, |
3556 | Note that, as with other watchers in libev, multiple events might get |
2831 | so while the overhead might be noticeable, it doesn't apply to repeated |
3557 | compressed into a single callback invocation (another way to look at |
2832 | calls to \f(CW\*(C`ev_async_send\*(C'\fR. |
3558 | this is that \f(CW\*(C`ev_async\*(C'\fR watchers are level-triggered: they are set on |
|
|
3559 | \&\f(CW\*(C`ev_async_send\*(C'\fR, reset when the event loop detects that). |
|
|
3560 | .Sp |
|
|
3561 | This call incurs the overhead of at most one extra system call per event |
|
|
3562 | loop iteration, if the event loop is blocked, and no syscall at all if |
|
|
3563 | the event loop (or your program) is processing events. That means that |
|
|
3564 | repeated calls are basically free (there is no need to avoid calls for |
|
|
3565 | performance reasons) and that the overhead becomes smaller (typically |
|
|
3566 | zero) under load. |
2833 | .IP "bool = ev_async_pending (ev_async *)" 4 |
3567 | .IP "bool = ev_async_pending (ev_async *)" 4 |
2834 | .IX Item "bool = ev_async_pending (ev_async *)" |
3568 | .IX Item "bool = ev_async_pending (ev_async *)" |
2835 | Returns a non-zero value when \f(CW\*(C`ev_async_send\*(C'\fR has been called on the |
3569 | Returns a non-zero value when \f(CW\*(C`ev_async_send\*(C'\fR has been called on the |
2836 | watcher but the event has not yet been processed (or even noted) by the |
3570 | watcher but the event has not yet been processed (or even noted) by the |
2837 | event loop. |
3571 | event loop. |
… | |
… | |
2839 | \&\f(CW\*(C`ev_async_send\*(C'\fR sets a flag in the watcher and wakes up the loop. When |
3573 | \&\f(CW\*(C`ev_async_send\*(C'\fR sets a flag in the watcher and wakes up the loop. When |
2840 | the loop iterates next and checks for the watcher to have become active, |
3574 | the loop iterates next and checks for the watcher to have become active, |
2841 | it will reset the flag again. \f(CW\*(C`ev_async_pending\*(C'\fR can be used to very |
3575 | it will reset the flag again. \f(CW\*(C`ev_async_pending\*(C'\fR can be used to very |
2842 | quickly check whether invoking the loop might be a good idea. |
3576 | quickly check whether invoking the loop might be a good idea. |
2843 | .Sp |
3577 | .Sp |
2844 | Not that this does \fInot\fR check whether the watcher itself is pending, only |
3578 | Not that this does \fInot\fR check whether the watcher itself is pending, |
2845 | whether it has been requested to make this watcher pending. |
3579 | only whether it has been requested to make this watcher pending: there |
|
|
3580 | is a time window between the event loop checking and resetting the async |
|
|
3581 | notification, and the callback being invoked. |
2846 | .SH "OTHER FUNCTIONS" |
3582 | .SH "OTHER FUNCTIONS" |
2847 | .IX Header "OTHER FUNCTIONS" |
3583 | .IX Header "OTHER FUNCTIONS" |
2848 | There are some other functions of possible interest. Described. Here. Now. |
3584 | There are some other functions of possible interest. Described. Here. Now. |
2849 | .IP "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" 4 |
3585 | .IP "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" 4 |
2850 | .IX Item "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" |
3586 | .IX Item "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" |
… | |
… | |
2860 | .Sp |
3596 | .Sp |
2861 | If \f(CW\*(C`timeout\*(C'\fR is less than 0, then no timeout watcher will be |
3597 | If \f(CW\*(C`timeout\*(C'\fR is less than 0, then no timeout watcher will be |
2862 | started. Otherwise an \f(CW\*(C`ev_timer\*(C'\fR watcher with after = \f(CW\*(C`timeout\*(C'\fR (and |
3598 | started. Otherwise an \f(CW\*(C`ev_timer\*(C'\fR watcher with after = \f(CW\*(C`timeout\*(C'\fR (and |
2863 | repeat = 0) will be started. \f(CW0\fR is a valid timeout. |
3599 | repeat = 0) will be started. \f(CW0\fR is a valid timeout. |
2864 | .Sp |
3600 | .Sp |
2865 | The callback has the type \f(CW\*(C`void (*cb)(int revents, void *arg)\*(C'\fR and gets |
3601 | The callback has the type \f(CW\*(C`void (*cb)(int revents, void *arg)\*(C'\fR and is |
2866 | passed an \f(CW\*(C`revents\*(C'\fR set like normal event callbacks (a combination of |
3602 | passed an \f(CW\*(C`revents\*(C'\fR set like normal event callbacks (a combination of |
2867 | \&\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 |
3603 | \&\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 |
2868 | value passed to \f(CW\*(C`ev_once\*(C'\fR. Note that it is possible to receive \fIboth\fR |
3604 | value passed to \f(CW\*(C`ev_once\*(C'\fR. Note that it is possible to receive \fIboth\fR |
2869 | a timeout and an io event at the same time \- you probably should give io |
3605 | a timeout and an io event at the same time \- you probably should give io |
2870 | events precedence. |
3606 | events precedence. |
2871 | .Sp |
3607 | .Sp |
2872 | Example: wait up to ten seconds for data to appear on \s-1STDIN_FILENO\s0. |
3608 | Example: wait up to ten seconds for data to appear on \s-1STDIN_FILENO\s0. |
… | |
… | |
2874 | .Vb 7 |
3610 | .Vb 7 |
2875 | \& static void stdin_ready (int revents, void *arg) |
3611 | \& static void stdin_ready (int revents, void *arg) |
2876 | \& { |
3612 | \& { |
2877 | \& if (revents & EV_READ) |
3613 | \& if (revents & EV_READ) |
2878 | \& /* stdin might have data for us, joy! */; |
3614 | \& /* stdin might have data for us, joy! */; |
2879 | \& else if (revents & EV_TIMEOUT) |
3615 | \& else if (revents & EV_TIMER) |
2880 | \& /* doh, nothing entered */; |
3616 | \& /* doh, nothing entered */; |
2881 | \& } |
3617 | \& } |
2882 | \& |
3618 | \& |
2883 | \& ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
3619 | \& ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
2884 | .Ve |
3620 | .Ve |
2885 | .IP "ev_feed_event (struct ev_loop *, watcher *, int revents)" 4 |
|
|
2886 | .IX Item "ev_feed_event (struct ev_loop *, watcher *, int revents)" |
|
|
2887 | Feeds the given event set into the event loop, as if the specified event |
|
|
2888 | had happened for the specified watcher (which must be a pointer to an |
|
|
2889 | initialised but not necessarily started event watcher). |
|
|
2890 | .IP "ev_feed_fd_event (struct ev_loop *, int fd, int revents)" 4 |
3621 | .IP "ev_feed_fd_event (loop, int fd, int revents)" 4 |
2891 | .IX Item "ev_feed_fd_event (struct ev_loop *, int fd, int revents)" |
3622 | .IX Item "ev_feed_fd_event (loop, int fd, int revents)" |
2892 | Feed an event on the given fd, as if a file descriptor backend detected |
3623 | Feed an event on the given fd, as if a file descriptor backend detected |
2893 | the given events it. |
3624 | the given events. |
2894 | .IP "ev_feed_signal_event (struct ev_loop *loop, int signum)" 4 |
3625 | .IP "ev_feed_signal_event (loop, int signum)" 4 |
2895 | .IX Item "ev_feed_signal_event (struct ev_loop *loop, int signum)" |
3626 | .IX Item "ev_feed_signal_event (loop, int signum)" |
2896 | Feed an event as if the given signal occurred (\f(CW\*(C`loop\*(C'\fR must be the default |
3627 | Feed an event as if the given signal occurred. See also \f(CW\*(C`ev_feed_signal\*(C'\fR, |
2897 | loop!). |
3628 | which is async-safe. |
|
|
3629 | .SH "COMMON OR USEFUL IDIOMS (OR BOTH)" |
|
|
3630 | .IX Header "COMMON OR USEFUL IDIOMS (OR BOTH)" |
|
|
3631 | This section explains some common idioms that are not immediately |
|
|
3632 | obvious. Note that examples are sprinkled over the whole manual, and this |
|
|
3633 | section only contains stuff that wouldn't fit anywhere else. |
|
|
3634 | .SS "\s-1ASSOCIATING\s0 \s-1CUSTOM\s0 \s-1DATA\s0 \s-1WITH\s0 A \s-1WATCHER\s0" |
|
|
3635 | .IX Subsection "ASSOCIATING CUSTOM DATA WITH A WATCHER" |
|
|
3636 | Each watcher has, by default, a \f(CW\*(C`void *data\*(C'\fR member that you can read |
|
|
3637 | or modify at any time: libev will completely ignore it. This can be used |
|
|
3638 | to associate arbitrary data with your watcher. If you need more data and |
|
|
3639 | don't want to allocate memory separately and store a pointer to it in that |
|
|
3640 | data member, you can also \*(L"subclass\*(R" the watcher type and provide your own |
|
|
3641 | data: |
|
|
3642 | .PP |
|
|
3643 | .Vb 7 |
|
|
3644 | \& struct my_io |
|
|
3645 | \& { |
|
|
3646 | \& ev_io io; |
|
|
3647 | \& int otherfd; |
|
|
3648 | \& void *somedata; |
|
|
3649 | \& struct whatever *mostinteresting; |
|
|
3650 | \& }; |
|
|
3651 | \& |
|
|
3652 | \& ... |
|
|
3653 | \& struct my_io w; |
|
|
3654 | \& ev_io_init (&w.io, my_cb, fd, EV_READ); |
|
|
3655 | .Ve |
|
|
3656 | .PP |
|
|
3657 | And since your callback will be called with a pointer to the watcher, you |
|
|
3658 | can cast it back to your own type: |
|
|
3659 | .PP |
|
|
3660 | .Vb 5 |
|
|
3661 | \& static void my_cb (struct ev_loop *loop, ev_io *w_, int revents) |
|
|
3662 | \& { |
|
|
3663 | \& struct my_io *w = (struct my_io *)w_; |
|
|
3664 | \& ... |
|
|
3665 | \& } |
|
|
3666 | .Ve |
|
|
3667 | .PP |
|
|
3668 | More interesting and less C\-conformant ways of casting your callback |
|
|
3669 | function type instead have been omitted. |
|
|
3670 | .SS "\s-1BUILDING\s0 \s-1YOUR\s0 \s-1OWN\s0 \s-1COMPOSITE\s0 \s-1WATCHERS\s0" |
|
|
3671 | .IX Subsection "BUILDING YOUR OWN COMPOSITE WATCHERS" |
|
|
3672 | Another common scenario is to use some data structure with multiple |
|
|
3673 | embedded watchers, in effect creating your own watcher that combines |
|
|
3674 | multiple libev event sources into one \*(L"super-watcher\*(R": |
|
|
3675 | .PP |
|
|
3676 | .Vb 6 |
|
|
3677 | \& struct my_biggy |
|
|
3678 | \& { |
|
|
3679 | \& int some_data; |
|
|
3680 | \& ev_timer t1; |
|
|
3681 | \& ev_timer t2; |
|
|
3682 | \& } |
|
|
3683 | .Ve |
|
|
3684 | .PP |
|
|
3685 | In this case getting the pointer to \f(CW\*(C`my_biggy\*(C'\fR is a bit more |
|
|
3686 | complicated: Either you store the address of your \f(CW\*(C`my_biggy\*(C'\fR struct in |
|
|
3687 | the \f(CW\*(C`data\*(C'\fR member of the watcher (for woozies or \*(C+ coders), or you need |
|
|
3688 | to use some pointer arithmetic using \f(CW\*(C`offsetof\*(C'\fR inside your watchers (for |
|
|
3689 | real programmers): |
|
|
3690 | .PP |
|
|
3691 | .Vb 1 |
|
|
3692 | \& #include <stddef.h> |
|
|
3693 | \& |
|
|
3694 | \& static void |
|
|
3695 | \& t1_cb (EV_P_ ev_timer *w, int revents) |
|
|
3696 | \& { |
|
|
3697 | \& struct my_biggy big = (struct my_biggy *) |
|
|
3698 | \& (((char *)w) \- offsetof (struct my_biggy, t1)); |
|
|
3699 | \& } |
|
|
3700 | \& |
|
|
3701 | \& static void |
|
|
3702 | \& t2_cb (EV_P_ ev_timer *w, int revents) |
|
|
3703 | \& { |
|
|
3704 | \& struct my_biggy big = (struct my_biggy *) |
|
|
3705 | \& (((char *)w) \- offsetof (struct my_biggy, t2)); |
|
|
3706 | \& } |
|
|
3707 | .Ve |
|
|
3708 | .SS "\s-1AVOIDING\s0 \s-1FINISHING\s0 \s-1BEFORE\s0 \s-1RETURNING\s0" |
|
|
3709 | .IX Subsection "AVOIDING FINISHING BEFORE RETURNING" |
|
|
3710 | Often you have structures like this in event-based programs: |
|
|
3711 | .PP |
|
|
3712 | .Vb 4 |
|
|
3713 | \& callback () |
|
|
3714 | \& { |
|
|
3715 | \& free (request); |
|
|
3716 | \& } |
|
|
3717 | \& |
|
|
3718 | \& request = start_new_request (..., callback); |
|
|
3719 | .Ve |
|
|
3720 | .PP |
|
|
3721 | The intent is to start some \*(L"lengthy\*(R" operation. The \f(CW\*(C`request\*(C'\fR could be |
|
|
3722 | used to cancel the operation, or do other things with it. |
|
|
3723 | .PP |
|
|
3724 | It's not uncommon to have code paths in \f(CW\*(C`start_new_request\*(C'\fR that |
|
|
3725 | immediately invoke the callback, for example, to report errors. Or you add |
|
|
3726 | some caching layer that finds that it can skip the lengthy aspects of the |
|
|
3727 | operation and simply invoke the callback with the result. |
|
|
3728 | .PP |
|
|
3729 | The problem here is that this will happen \fIbefore\fR \f(CW\*(C`start_new_request\*(C'\fR |
|
|
3730 | has returned, so \f(CW\*(C`request\*(C'\fR is not set. |
|
|
3731 | .PP |
|
|
3732 | Even if you pass the request by some safer means to the callback, you |
|
|
3733 | might want to do something to the request after starting it, such as |
|
|
3734 | canceling it, which probably isn't working so well when the callback has |
|
|
3735 | already been invoked. |
|
|
3736 | .PP |
|
|
3737 | A common way around all these issues is to make sure that |
|
|
3738 | \&\f(CW\*(C`start_new_request\*(C'\fR \fIalways\fR returns before the callback is invoked. If |
|
|
3739 | \&\f(CW\*(C`start_new_request\*(C'\fR immediately knows the result, it can artificially |
|
|
3740 | delay invoking the callback by e.g. using a \f(CW\*(C`prepare\*(C'\fR or \f(CW\*(C`idle\*(C'\fR watcher |
|
|
3741 | for example, or more sneakily, by reusing an existing (stopped) watcher |
|
|
3742 | and pushing it into the pending queue: |
|
|
3743 | .PP |
|
|
3744 | .Vb 2 |
|
|
3745 | \& ev_set_cb (watcher, callback); |
|
|
3746 | \& ev_feed_event (EV_A_ watcher, 0); |
|
|
3747 | .Ve |
|
|
3748 | .PP |
|
|
3749 | This way, \f(CW\*(C`start_new_request\*(C'\fR can safely return before the callback is |
|
|
3750 | invoked, while not delaying callback invocation too much. |
|
|
3751 | .SS "\s-1MODEL/NESTED\s0 \s-1EVENT\s0 \s-1LOOP\s0 \s-1INVOCATIONS\s0 \s-1AND\s0 \s-1EXIT\s0 \s-1CONDITIONS\s0" |
|
|
3752 | .IX Subsection "MODEL/NESTED EVENT LOOP INVOCATIONS AND EXIT CONDITIONS" |
|
|
3753 | Often (especially in \s-1GUI\s0 toolkits) there are places where you have |
|
|
3754 | \&\fImodal\fR interaction, which is most easily implemented by recursively |
|
|
3755 | invoking \f(CW\*(C`ev_run\*(C'\fR. |
|
|
3756 | .PP |
|
|
3757 | This brings the problem of exiting \- a callback might want to finish the |
|
|
3758 | main \f(CW\*(C`ev_run\*(C'\fR call, but not the nested one (e.g. user clicked \*(L"Quit\*(R", but |
|
|
3759 | a modal \*(L"Are you sure?\*(R" dialog is still waiting), or just the nested one |
|
|
3760 | and not the main one (e.g. user clocked \*(L"Ok\*(R" in a modal dialog), or some |
|
|
3761 | other combination: In these cases, \f(CW\*(C`ev_break\*(C'\fR will not work alone. |
|
|
3762 | .PP |
|
|
3763 | The solution is to maintain \*(L"break this loop\*(R" variable for each \f(CW\*(C`ev_run\*(C'\fR |
|
|
3764 | invocation, and use a loop around \f(CW\*(C`ev_run\*(C'\fR until the condition is |
|
|
3765 | triggered, using \f(CW\*(C`EVRUN_ONCE\*(C'\fR: |
|
|
3766 | .PP |
|
|
3767 | .Vb 2 |
|
|
3768 | \& // main loop |
|
|
3769 | \& int exit_main_loop = 0; |
|
|
3770 | \& |
|
|
3771 | \& while (!exit_main_loop) |
|
|
3772 | \& ev_run (EV_DEFAULT_ EVRUN_ONCE); |
|
|
3773 | \& |
|
|
3774 | \& // in a modal watcher |
|
|
3775 | \& int exit_nested_loop = 0; |
|
|
3776 | \& |
|
|
3777 | \& while (!exit_nested_loop) |
|
|
3778 | \& ev_run (EV_A_ EVRUN_ONCE); |
|
|
3779 | .Ve |
|
|
3780 | .PP |
|
|
3781 | To exit from any of these loops, just set the corresponding exit variable: |
|
|
3782 | .PP |
|
|
3783 | .Vb 2 |
|
|
3784 | \& // exit modal loop |
|
|
3785 | \& exit_nested_loop = 1; |
|
|
3786 | \& |
|
|
3787 | \& // exit main program, after modal loop is finished |
|
|
3788 | \& exit_main_loop = 1; |
|
|
3789 | \& |
|
|
3790 | \& // exit both |
|
|
3791 | \& exit_main_loop = exit_nested_loop = 1; |
|
|
3792 | .Ve |
|
|
3793 | .SS "\s-1THREAD\s0 \s-1LOCKING\s0 \s-1EXAMPLE\s0" |
|
|
3794 | .IX Subsection "THREAD LOCKING EXAMPLE" |
|
|
3795 | Here is a fictitious example of how to run an event loop in a different |
|
|
3796 | thread from where callbacks are being invoked and watchers are |
|
|
3797 | created/added/removed. |
|
|
3798 | .PP |
|
|
3799 | For a real-world example, see the \f(CW\*(C`EV::Loop::Async\*(C'\fR perl module, |
|
|
3800 | which uses exactly this technique (which is suited for many high-level |
|
|
3801 | languages). |
|
|
3802 | .PP |
|
|
3803 | The example uses a pthread mutex to protect the loop data, a condition |
|
|
3804 | variable to wait for callback invocations, an async watcher to notify the |
|
|
3805 | event loop thread and an unspecified mechanism to wake up the main thread. |
|
|
3806 | .PP |
|
|
3807 | First, you need to associate some data with the event loop: |
|
|
3808 | .PP |
|
|
3809 | .Vb 6 |
|
|
3810 | \& typedef struct { |
|
|
3811 | \& mutex_t lock; /* global loop lock */ |
|
|
3812 | \& ev_async async_w; |
|
|
3813 | \& thread_t tid; |
|
|
3814 | \& cond_t invoke_cv; |
|
|
3815 | \& } userdata; |
|
|
3816 | \& |
|
|
3817 | \& void prepare_loop (EV_P) |
|
|
3818 | \& { |
|
|
3819 | \& // for simplicity, we use a static userdata struct. |
|
|
3820 | \& static userdata u; |
|
|
3821 | \& |
|
|
3822 | \& ev_async_init (&u\->async_w, async_cb); |
|
|
3823 | \& ev_async_start (EV_A_ &u\->async_w); |
|
|
3824 | \& |
|
|
3825 | \& pthread_mutex_init (&u\->lock, 0); |
|
|
3826 | \& pthread_cond_init (&u\->invoke_cv, 0); |
|
|
3827 | \& |
|
|
3828 | \& // now associate this with the loop |
|
|
3829 | \& ev_set_userdata (EV_A_ u); |
|
|
3830 | \& ev_set_invoke_pending_cb (EV_A_ l_invoke); |
|
|
3831 | \& ev_set_loop_release_cb (EV_A_ l_release, l_acquire); |
|
|
3832 | \& |
|
|
3833 | \& // then create the thread running ev_run |
|
|
3834 | \& pthread_create (&u\->tid, 0, l_run, EV_A); |
|
|
3835 | \& } |
|
|
3836 | .Ve |
|
|
3837 | .PP |
|
|
3838 | The callback for the \f(CW\*(C`ev_async\*(C'\fR watcher does nothing: the watcher is used |
|
|
3839 | solely to wake up the event loop so it takes notice of any new watchers |
|
|
3840 | that might have been added: |
|
|
3841 | .PP |
|
|
3842 | .Vb 5 |
|
|
3843 | \& static void |
|
|
3844 | \& async_cb (EV_P_ ev_async *w, int revents) |
|
|
3845 | \& { |
|
|
3846 | \& // just used for the side effects |
|
|
3847 | \& } |
|
|
3848 | .Ve |
|
|
3849 | .PP |
|
|
3850 | The \f(CW\*(C`l_release\*(C'\fR and \f(CW\*(C`l_acquire\*(C'\fR callbacks simply unlock/lock the mutex |
|
|
3851 | protecting the loop data, respectively. |
|
|
3852 | .PP |
|
|
3853 | .Vb 6 |
|
|
3854 | \& static void |
|
|
3855 | \& l_release (EV_P) |
|
|
3856 | \& { |
|
|
3857 | \& userdata *u = ev_userdata (EV_A); |
|
|
3858 | \& pthread_mutex_unlock (&u\->lock); |
|
|
3859 | \& } |
|
|
3860 | \& |
|
|
3861 | \& static void |
|
|
3862 | \& l_acquire (EV_P) |
|
|
3863 | \& { |
|
|
3864 | \& userdata *u = ev_userdata (EV_A); |
|
|
3865 | \& pthread_mutex_lock (&u\->lock); |
|
|
3866 | \& } |
|
|
3867 | .Ve |
|
|
3868 | .PP |
|
|
3869 | The event loop thread first acquires the mutex, and then jumps straight |
|
|
3870 | into \f(CW\*(C`ev_run\*(C'\fR: |
|
|
3871 | .PP |
|
|
3872 | .Vb 4 |
|
|
3873 | \& void * |
|
|
3874 | \& l_run (void *thr_arg) |
|
|
3875 | \& { |
|
|
3876 | \& struct ev_loop *loop = (struct ev_loop *)thr_arg; |
|
|
3877 | \& |
|
|
3878 | \& l_acquire (EV_A); |
|
|
3879 | \& pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0); |
|
|
3880 | \& ev_run (EV_A_ 0); |
|
|
3881 | \& l_release (EV_A); |
|
|
3882 | \& |
|
|
3883 | \& return 0; |
|
|
3884 | \& } |
|
|
3885 | .Ve |
|
|
3886 | .PP |
|
|
3887 | Instead of invoking all pending watchers, the \f(CW\*(C`l_invoke\*(C'\fR callback will |
|
|
3888 | signal the main thread via some unspecified mechanism (signals? pipe |
|
|
3889 | writes? \f(CW\*(C`Async::Interrupt\*(C'\fR?) and then waits until all pending watchers |
|
|
3890 | have been called (in a while loop because a) spurious wakeups are possible |
|
|
3891 | and b) skipping inter-thread-communication when there are no pending |
|
|
3892 | watchers is very beneficial): |
|
|
3893 | .PP |
|
|
3894 | .Vb 4 |
|
|
3895 | \& static void |
|
|
3896 | \& l_invoke (EV_P) |
|
|
3897 | \& { |
|
|
3898 | \& userdata *u = ev_userdata (EV_A); |
|
|
3899 | \& |
|
|
3900 | \& while (ev_pending_count (EV_A)) |
|
|
3901 | \& { |
|
|
3902 | \& wake_up_other_thread_in_some_magic_or_not_so_magic_way (); |
|
|
3903 | \& pthread_cond_wait (&u\->invoke_cv, &u\->lock); |
|
|
3904 | \& } |
|
|
3905 | \& } |
|
|
3906 | .Ve |
|
|
3907 | .PP |
|
|
3908 | Now, whenever the main thread gets told to invoke pending watchers, it |
|
|
3909 | will grab the lock, call \f(CW\*(C`ev_invoke_pending\*(C'\fR and then signal the loop |
|
|
3910 | thread to continue: |
|
|
3911 | .PP |
|
|
3912 | .Vb 4 |
|
|
3913 | \& static void |
|
|
3914 | \& real_invoke_pending (EV_P) |
|
|
3915 | \& { |
|
|
3916 | \& userdata *u = ev_userdata (EV_A); |
|
|
3917 | \& |
|
|
3918 | \& pthread_mutex_lock (&u\->lock); |
|
|
3919 | \& ev_invoke_pending (EV_A); |
|
|
3920 | \& pthread_cond_signal (&u\->invoke_cv); |
|
|
3921 | \& pthread_mutex_unlock (&u\->lock); |
|
|
3922 | \& } |
|
|
3923 | .Ve |
|
|
3924 | .PP |
|
|
3925 | Whenever you want to start/stop a watcher or do other modifications to an |
|
|
3926 | event loop, you will now have to lock: |
|
|
3927 | .PP |
|
|
3928 | .Vb 2 |
|
|
3929 | \& ev_timer timeout_watcher; |
|
|
3930 | \& userdata *u = ev_userdata (EV_A); |
|
|
3931 | \& |
|
|
3932 | \& ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.); |
|
|
3933 | \& |
|
|
3934 | \& pthread_mutex_lock (&u\->lock); |
|
|
3935 | \& ev_timer_start (EV_A_ &timeout_watcher); |
|
|
3936 | \& ev_async_send (EV_A_ &u\->async_w); |
|
|
3937 | \& pthread_mutex_unlock (&u\->lock); |
|
|
3938 | .Ve |
|
|
3939 | .PP |
|
|
3940 | Note that sending the \f(CW\*(C`ev_async\*(C'\fR watcher is required because otherwise |
|
|
3941 | an event loop currently blocking in the kernel will have no knowledge |
|
|
3942 | about the newly added timer. By waking up the loop it will pick up any new |
|
|
3943 | watchers in the next event loop iteration. |
|
|
3944 | .SS "\s-1THREADS\s0, \s-1COROUTINES\s0, \s-1CONTINUATIONS\s0, \s-1QUEUES\s0... \s-1INSTEAD\s0 \s-1OF\s0 \s-1CALLBACKS\s0" |
|
|
3945 | .IX Subsection "THREADS, COROUTINES, CONTINUATIONS, QUEUES... INSTEAD OF CALLBACKS" |
|
|
3946 | While the overhead of a callback that e.g. schedules a thread is small, it |
|
|
3947 | is still an overhead. If you embed libev, and your main usage is with some |
|
|
3948 | kind of threads or coroutines, you might want to customise libev so that |
|
|
3949 | doesn't need callbacks anymore. |
|
|
3950 | .PP |
|
|
3951 | Imagine you have coroutines that you can switch to using a function |
|
|
3952 | \&\f(CW\*(C`switch_to (coro)\*(C'\fR, that libev runs in a coroutine called \f(CW\*(C`libev_coro\*(C'\fR |
|
|
3953 | and that due to some magic, the currently active coroutine is stored in a |
|
|
3954 | global called \f(CW\*(C`current_coro\*(C'\fR. Then you can build your own \*(L"wait for libev |
|
|
3955 | event\*(R" primitive by changing \f(CW\*(C`EV_CB_DECLARE\*(C'\fR and \f(CW\*(C`EV_CB_INVOKE\*(C'\fR (note |
|
|
3956 | the differing \f(CW\*(C`;\*(C'\fR conventions): |
|
|
3957 | .PP |
|
|
3958 | .Vb 2 |
|
|
3959 | \& #define EV_CB_DECLARE(type) struct my_coro *cb; |
|
|
3960 | \& #define EV_CB_INVOKE(watcher) switch_to ((watcher)\->cb) |
|
|
3961 | .Ve |
|
|
3962 | .PP |
|
|
3963 | That means instead of having a C callback function, you store the |
|
|
3964 | coroutine to switch to in each watcher, and instead of having libev call |
|
|
3965 | your callback, you instead have it switch to that coroutine. |
|
|
3966 | .PP |
|
|
3967 | A coroutine might now wait for an event with a function called |
|
|
3968 | \&\f(CW\*(C`wait_for_event\*(C'\fR. (the watcher needs to be started, as always, but it doesn't |
|
|
3969 | matter when, or whether the watcher is active or not when this function is |
|
|
3970 | called): |
|
|
3971 | .PP |
|
|
3972 | .Vb 6 |
|
|
3973 | \& void |
|
|
3974 | \& wait_for_event (ev_watcher *w) |
|
|
3975 | \& { |
|
|
3976 | \& ev_cb_set (w) = current_coro; |
|
|
3977 | \& switch_to (libev_coro); |
|
|
3978 | \& } |
|
|
3979 | .Ve |
|
|
3980 | .PP |
|
|
3981 | That basically suspends the coroutine inside \f(CW\*(C`wait_for_event\*(C'\fR and |
|
|
3982 | continues the libev coroutine, which, when appropriate, switches back to |
|
|
3983 | this or any other coroutine. |
|
|
3984 | .PP |
|
|
3985 | You can do similar tricks if you have, say, threads with an event queue \- |
|
|
3986 | instead of storing a coroutine, you store the queue object and instead of |
|
|
3987 | switching to a coroutine, you push the watcher onto the queue and notify |
|
|
3988 | any waiters. |
|
|
3989 | .PP |
|
|
3990 | To embed libev, see \s-1EMBEDDING\s0, but in short, it's easiest to create two |
|
|
3991 | files, \fImy_ev.h\fR and \fImy_ev.c\fR that include the respective libev files: |
|
|
3992 | .PP |
|
|
3993 | .Vb 4 |
|
|
3994 | \& // my_ev.h |
|
|
3995 | \& #define EV_CB_DECLARE(type) struct my_coro *cb; |
|
|
3996 | \& #define EV_CB_INVOKE(watcher) switch_to ((watcher)\->cb); |
|
|
3997 | \& #include "../libev/ev.h" |
|
|
3998 | \& |
|
|
3999 | \& // my_ev.c |
|
|
4000 | \& #define EV_H "my_ev.h" |
|
|
4001 | \& #include "../libev/ev.c" |
|
|
4002 | .Ve |
|
|
4003 | .PP |
|
|
4004 | And then use \fImy_ev.h\fR when you would normally use \fIev.h\fR, and compile |
|
|
4005 | \&\fImy_ev.c\fR into your project. When properly specifying include paths, you |
|
|
4006 | can even use \fIev.h\fR as header file name directly. |
2898 | .SH "LIBEVENT EMULATION" |
4007 | .SH "LIBEVENT EMULATION" |
2899 | .IX Header "LIBEVENT EMULATION" |
4008 | .IX Header "LIBEVENT EMULATION" |
2900 | Libev offers a compatibility emulation layer for libevent. It cannot |
4009 | Libev offers a compatibility emulation layer for libevent. It cannot |
2901 | emulate the internals of libevent, so here are some usage hints: |
4010 | emulate the internals of libevent, so here are some usage hints: |
|
|
4011 | .IP "\(bu" 4 |
|
|
4012 | Only the libevent\-1.4.1\-beta \s-1API\s0 is being emulated. |
|
|
4013 | .Sp |
|
|
4014 | This was the newest libevent version available when libev was implemented, |
|
|
4015 | and is still mostly unchanged in 2010. |
2902 | .IP "\(bu" 4 |
4016 | .IP "\(bu" 4 |
2903 | Use it by including <event.h>, as usual. |
4017 | Use it by including <event.h>, as usual. |
2904 | .IP "\(bu" 4 |
4018 | .IP "\(bu" 4 |
2905 | The following members are fully supported: ev_base, ev_callback, |
4019 | The following members are fully supported: ev_base, ev_callback, |
2906 | ev_arg, ev_fd, ev_res, ev_events. |
4020 | ev_arg, ev_fd, ev_res, ev_events. |
… | |
… | |
2912 | Priorities are not currently supported. Initialising priorities |
4026 | Priorities are not currently supported. Initialising priorities |
2913 | will fail and all watchers will have the same priority, even though there |
4027 | will fail and all watchers will have the same priority, even though there |
2914 | is an ev_pri field. |
4028 | is an ev_pri field. |
2915 | .IP "\(bu" 4 |
4029 | .IP "\(bu" 4 |
2916 | In libevent, the last base created gets the signals, in libev, the |
4030 | In libevent, the last base created gets the signals, in libev, the |
2917 | first base created (== the default loop) gets the signals. |
4031 | base that registered the signal gets the signals. |
2918 | .IP "\(bu" 4 |
4032 | .IP "\(bu" 4 |
2919 | Other members are not supported. |
4033 | Other members are not supported. |
2920 | .IP "\(bu" 4 |
4034 | .IP "\(bu" 4 |
2921 | The libev emulation is \fInot\fR \s-1ABI\s0 compatible to libevent, you need |
4035 | The libev emulation is \fInot\fR \s-1ABI\s0 compatible to libevent, you need |
2922 | to use the libev header file and library. |
4036 | to use the libev header file and library. |
… | |
… | |
2940 | Care has been taken to keep the overhead low. The only data member the \*(C+ |
4054 | Care has been taken to keep the overhead low. The only data member the \*(C+ |
2941 | classes add (compared to plain C\-style watchers) is the event loop pointer |
4055 | classes add (compared to plain C\-style watchers) is the event loop pointer |
2942 | that the watcher is associated with (or no additional members at all if |
4056 | that the watcher is associated with (or no additional members at all if |
2943 | you disable \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR when embedding libev). |
4057 | you disable \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR when embedding libev). |
2944 | .PP |
4058 | .PP |
2945 | Currently, functions, and static and non-static member functions can be |
4059 | Currently, functions, static and non-static member functions and classes |
2946 | used as callbacks. Other types should be easy to add as long as they only |
4060 | with \f(CW\*(C`operator ()\*(C'\fR can be used as callbacks. Other types should be easy |
2947 | need one additional pointer for context. If you need support for other |
4061 | to add as long as they only need one additional pointer for context. If |
2948 | types of functors please contact the author (preferably after implementing |
4062 | you need support for other types of functors please contact the author |
2949 | it). |
4063 | (preferably after implementing it). |
|
|
4064 | .PP |
|
|
4065 | For all this to work, your \*(C+ compiler either has to use the same calling |
|
|
4066 | conventions as your C compiler (for static member functions), or you have |
|
|
4067 | to embed libev and compile libev itself as \*(C+. |
2950 | .PP |
4068 | .PP |
2951 | Here is a list of things available in the \f(CW\*(C`ev\*(C'\fR namespace: |
4069 | Here is a list of things available in the \f(CW\*(C`ev\*(C'\fR namespace: |
2952 | .ie n .IP """ev::READ""\fR, \f(CW""ev::WRITE"" etc." 4 |
4070 | .ie n .IP """ev::READ"", ""ev::WRITE"" etc." 4 |
2953 | .el .IP "\f(CWev::READ\fR, \f(CWev::WRITE\fR etc." 4 |
4071 | .el .IP "\f(CWev::READ\fR, \f(CWev::WRITE\fR etc." 4 |
2954 | .IX Item "ev::READ, ev::WRITE etc." |
4072 | .IX Item "ev::READ, ev::WRITE etc." |
2955 | These are just enum values with the same values as the \f(CW\*(C`EV_READ\*(C'\fR etc. |
4073 | These are just enum values with the same values as the \f(CW\*(C`EV_READ\*(C'\fR etc. |
2956 | macros from \fIev.h\fR. |
4074 | macros from \fIev.h\fR. |
2957 | .ie n .IP """ev::tstamp""\fR, \f(CW""ev::now""" 4 |
4075 | .ie n .IP """ev::tstamp"", ""ev::now""" 4 |
2958 | .el .IP "\f(CWev::tstamp\fR, \f(CWev::now\fR" 4 |
4076 | .el .IP "\f(CWev::tstamp\fR, \f(CWev::now\fR" 4 |
2959 | .IX Item "ev::tstamp, ev::now" |
4077 | .IX Item "ev::tstamp, ev::now" |
2960 | Aliases to the same types/functions as with the \f(CW\*(C`ev_\*(C'\fR prefix. |
4078 | Aliases to the same types/functions as with the \f(CW\*(C`ev_\*(C'\fR prefix. |
2961 | .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 |
4079 | .ie n .IP """ev::io"", ""ev::timer"", ""ev::periodic"", ""ev::idle"", ""ev::sig"" etc." 4 |
2962 | .el .IP "\f(CWev::io\fR, \f(CWev::timer\fR, \f(CWev::periodic\fR, \f(CWev::idle\fR, \f(CWev::sig\fR etc." 4 |
4080 | .el .IP "\f(CWev::io\fR, \f(CWev::timer\fR, \f(CWev::periodic\fR, \f(CWev::idle\fR, \f(CWev::sig\fR etc." 4 |
2963 | .IX Item "ev::io, ev::timer, ev::periodic, ev::idle, ev::sig etc." |
4081 | .IX Item "ev::io, ev::timer, ev::periodic, ev::idle, ev::sig etc." |
2964 | For each \f(CW\*(C`ev_TYPE\*(C'\fR watcher in \fIev.h\fR there is a corresponding class of |
4082 | For each \f(CW\*(C`ev_TYPE\*(C'\fR watcher in \fIev.h\fR there is a corresponding class of |
2965 | the same name in the \f(CW\*(C`ev\*(C'\fR namespace, with the exception of \f(CW\*(C`ev_signal\*(C'\fR |
4083 | the same name in the \f(CW\*(C`ev\*(C'\fR namespace, with the exception of \f(CW\*(C`ev_signal\*(C'\fR |
2966 | which is called \f(CW\*(C`ev::sig\*(C'\fR to avoid clashes with the \f(CW\*(C`signal\*(C'\fR macro |
4084 | which is called \f(CW\*(C`ev::sig\*(C'\fR to avoid clashes with the \f(CW\*(C`signal\*(C'\fR macro |
2967 | defines by many implementations. |
4085 | defined by many implementations. |
2968 | .Sp |
4086 | .Sp |
2969 | All of those classes have these methods: |
4087 | All of those classes have these methods: |
2970 | .RS 4 |
4088 | .RS 4 |
2971 | .IP "ev::TYPE::TYPE ()" 4 |
4089 | .IP "ev::TYPE::TYPE ()" 4 |
2972 | .IX Item "ev::TYPE::TYPE ()" |
4090 | .IX Item "ev::TYPE::TYPE ()" |
2973 | .PD 0 |
4091 | .PD 0 |
2974 | .IP "ev::TYPE::TYPE (struct ev_loop *)" 4 |
4092 | .IP "ev::TYPE::TYPE (loop)" 4 |
2975 | .IX Item "ev::TYPE::TYPE (struct ev_loop *)" |
4093 | .IX Item "ev::TYPE::TYPE (loop)" |
2976 | .IP "ev::TYPE::~TYPE" 4 |
4094 | .IP "ev::TYPE::~TYPE" 4 |
2977 | .IX Item "ev::TYPE::~TYPE" |
4095 | .IX Item "ev::TYPE::~TYPE" |
2978 | .PD |
4096 | .PD |
2979 | The constructor (optionally) takes an event loop to associate the watcher |
4097 | The constructor (optionally) takes an event loop to associate the watcher |
2980 | with. If it is omitted, it will use \f(CW\*(C`EV_DEFAULT\*(C'\fR. |
4098 | with. If it is omitted, it will use \f(CW\*(C`EV_DEFAULT\*(C'\fR. |
… | |
… | |
3014 | \& ev::io iow; |
4132 | \& ev::io iow; |
3015 | \& iow.set <myclass, &myclass::io_cb> (&obj); |
4133 | \& iow.set <myclass, &myclass::io_cb> (&obj); |
3016 | .Ve |
4134 | .Ve |
3017 | .IP "w\->set (object *)" 4 |
4135 | .IP "w\->set (object *)" 4 |
3018 | .IX Item "w->set (object *)" |
4136 | .IX Item "w->set (object *)" |
3019 | This is an \fBexperimental\fR feature that might go away in a future version. |
|
|
3020 | .Sp |
|
|
3021 | This is a variation of a method callback \- leaving out the method to call |
4137 | This is a variation of a method callback \- leaving out the method to call |
3022 | will default the method to \f(CW\*(C`operator ()\*(C'\fR, which makes it possible to use |
4138 | will default the method to \f(CW\*(C`operator ()\*(C'\fR, which makes it possible to use |
3023 | functor objects without having to manually specify the \f(CW\*(C`operator ()\*(C'\fR all |
4139 | functor objects without having to manually specify the \f(CW\*(C`operator ()\*(C'\fR all |
3024 | the time. Incidentally, you can then also leave out the template argument |
4140 | the time. Incidentally, you can then also leave out the template argument |
3025 | list. |
4141 | list. |
… | |
… | |
3059 | .Sp |
4175 | .Sp |
3060 | .Vb 2 |
4176 | .Vb 2 |
3061 | \& static void io_cb (ev::io &w, int revents) { } |
4177 | \& static void io_cb (ev::io &w, int revents) { } |
3062 | \& iow.set <io_cb> (); |
4178 | \& iow.set <io_cb> (); |
3063 | .Ve |
4179 | .Ve |
3064 | .IP "w\->set (struct ev_loop *)" 4 |
4180 | .IP "w\->set (loop)" 4 |
3065 | .IX Item "w->set (struct ev_loop *)" |
4181 | .IX Item "w->set (loop)" |
3066 | Associates a different \f(CW\*(C`struct ev_loop\*(C'\fR with this watcher. You can only |
4182 | Associates a different \f(CW\*(C`struct ev_loop\*(C'\fR with this watcher. You can only |
3067 | do this when the watcher is inactive (and not pending either). |
4183 | do this when the watcher is inactive (and not pending either). |
3068 | .IP "w\->set ([arguments])" 4 |
4184 | .IP "w\->set ([arguments])" 4 |
3069 | .IX Item "w->set ([arguments])" |
4185 | .IX Item "w->set ([arguments])" |
3070 | Basically the same as \f(CW\*(C`ev_TYPE_set\*(C'\fR, with the same arguments. Must be |
4186 | Basically the same as \f(CW\*(C`ev_TYPE_set\*(C'\fR, with the same arguments. Either this |
3071 | called at least once. Unlike the C counterpart, an active watcher gets |
4187 | method or a suitable start method must be called at least once. Unlike the |
3072 | automatically stopped and restarted when reconfiguring it with this |
4188 | C counterpart, an active watcher gets automatically stopped and restarted |
3073 | method. |
4189 | when reconfiguring it with this method. |
3074 | .IP "w\->start ()" 4 |
4190 | .IP "w\->start ()" 4 |
3075 | .IX Item "w->start ()" |
4191 | .IX Item "w->start ()" |
3076 | Starts the watcher. Note that there is no \f(CW\*(C`loop\*(C'\fR argument, as the |
4192 | Starts the watcher. Note that there is no \f(CW\*(C`loop\*(C'\fR argument, as the |
3077 | constructor already stores the event loop. |
4193 | constructor already stores the event loop. |
|
|
4194 | .IP "w\->start ([arguments])" 4 |
|
|
4195 | .IX Item "w->start ([arguments])" |
|
|
4196 | Instead of calling \f(CW\*(C`set\*(C'\fR and \f(CW\*(C`start\*(C'\fR methods separately, it is often |
|
|
4197 | convenient to wrap them in one call. Uses the same type of arguments as |
|
|
4198 | the configure \f(CW\*(C`set\*(C'\fR method of the watcher. |
3078 | .IP "w\->stop ()" 4 |
4199 | .IP "w\->stop ()" 4 |
3079 | .IX Item "w->stop ()" |
4200 | .IX Item "w->stop ()" |
3080 | Stops the watcher if it is active. Again, no \f(CW\*(C`loop\*(C'\fR argument. |
4201 | Stops the watcher if it is active. Again, no \f(CW\*(C`loop\*(C'\fR argument. |
3081 | .ie n .IP "w\->again () (""ev::timer""\fR, \f(CW""ev::periodic"" only)" 4 |
4202 | .ie n .IP "w\->again () (""ev::timer"", ""ev::periodic"" only)" 4 |
3082 | .el .IP "w\->again () (\f(CWev::timer\fR, \f(CWev::periodic\fR only)" 4 |
4203 | .el .IP "w\->again () (\f(CWev::timer\fR, \f(CWev::periodic\fR only)" 4 |
3083 | .IX Item "w->again () (ev::timer, ev::periodic only)" |
4204 | .IX Item "w->again () (ev::timer, ev::periodic only)" |
3084 | For \f(CW\*(C`ev::timer\*(C'\fR and \f(CW\*(C`ev::periodic\*(C'\fR, this invokes the corresponding |
4205 | For \f(CW\*(C`ev::timer\*(C'\fR and \f(CW\*(C`ev::periodic\*(C'\fR, this invokes the corresponding |
3085 | \&\f(CW\*(C`ev_TYPE_again\*(C'\fR function. |
4206 | \&\f(CW\*(C`ev_TYPE_again\*(C'\fR function. |
3086 | .ie n .IP "w\->sweep () (""ev::embed"" only)" 4 |
4207 | .ie n .IP "w\->sweep () (""ev::embed"" only)" 4 |
… | |
… | |
3093 | Invokes \f(CW\*(C`ev_stat_stat\*(C'\fR. |
4214 | Invokes \f(CW\*(C`ev_stat_stat\*(C'\fR. |
3094 | .RE |
4215 | .RE |
3095 | .RS 4 |
4216 | .RS 4 |
3096 | .RE |
4217 | .RE |
3097 | .PP |
4218 | .PP |
3098 | Example: Define a class with an \s-1IO\s0 and idle watcher, start one of them in |
4219 | Example: Define a class with two I/O and idle watchers, start the I/O |
3099 | the constructor. |
4220 | watchers in the constructor. |
3100 | .PP |
4221 | .PP |
3101 | .Vb 4 |
4222 | .Vb 5 |
3102 | \& class myclass |
4223 | \& class myclass |
3103 | \& { |
4224 | \& { |
3104 | \& ev::io io ; void io_cb (ev::io &w, int revents); |
4225 | \& ev::io io ; void io_cb (ev::io &w, int revents); |
|
|
4226 | \& ev::io io2 ; void io2_cb (ev::io &w, int revents); |
3105 | \& ev::idle idle; void idle_cb (ev::idle &w, int revents); |
4227 | \& ev::idle idle; void idle_cb (ev::idle &w, int revents); |
3106 | \& |
4228 | \& |
3107 | \& myclass (int fd) |
4229 | \& myclass (int fd) |
3108 | \& { |
4230 | \& { |
3109 | \& io .set <myclass, &myclass::io_cb > (this); |
4231 | \& io .set <myclass, &myclass::io_cb > (this); |
|
|
4232 | \& io2 .set <myclass, &myclass::io2_cb > (this); |
3110 | \& idle.set <myclass, &myclass::idle_cb> (this); |
4233 | \& idle.set <myclass, &myclass::idle_cb> (this); |
3111 | \& |
4234 | \& |
3112 | \& io.start (fd, ev::READ); |
4235 | \& io.set (fd, ev::WRITE); // configure the watcher |
|
|
4236 | \& io.start (); // start it whenever convenient |
|
|
4237 | \& |
|
|
4238 | \& io2.start (fd, ev::READ); // set + start in one call |
3113 | \& } |
4239 | \& } |
3114 | \& }; |
4240 | \& }; |
3115 | .Ve |
4241 | .Ve |
3116 | .SH "OTHER LANGUAGE BINDINGS" |
4242 | .SH "OTHER LANGUAGE BINDINGS" |
3117 | .IX Header "OTHER LANGUAGE BINDINGS" |
4243 | .IX Header "OTHER LANGUAGE BINDINGS" |
… | |
… | |
3131 | It can be found and installed via \s-1CPAN\s0, its homepage is at |
4257 | It can be found and installed via \s-1CPAN\s0, its homepage is at |
3132 | <http://software.schmorp.de/pkg/EV>. |
4258 | <http://software.schmorp.de/pkg/EV>. |
3133 | .IP "Python" 4 |
4259 | .IP "Python" 4 |
3134 | .IX Item "Python" |
4260 | .IX Item "Python" |
3135 | Python bindings can be found at <http://code.google.com/p/pyev/>. It |
4261 | Python bindings can be found at <http://code.google.com/p/pyev/>. It |
3136 | seems to be quite complete and well-documented. Note, however, that the |
4262 | seems to be quite complete and well-documented. |
3137 | patch they require for libev is outright dangerous as it breaks the \s-1ABI\s0 |
|
|
3138 | for everybody else, and therefore, should never be applied in an installed |
|
|
3139 | libev (if python requires an incompatible \s-1ABI\s0 then it needs to embed |
|
|
3140 | libev). |
|
|
3141 | .IP "Ruby" 4 |
4263 | .IP "Ruby" 4 |
3142 | .IX Item "Ruby" |
4264 | .IX Item "Ruby" |
3143 | Tony Arcieri has written a ruby extension that offers access to a subset |
4265 | Tony Arcieri has written a ruby extension that offers access to a subset |
3144 | of the libev \s-1API\s0 and adds file handle abstractions, asynchronous \s-1DNS\s0 and |
4266 | of the libev \s-1API\s0 and adds file handle abstractions, asynchronous \s-1DNS\s0 and |
3145 | more on top of it. It can be found via gem servers. Its homepage is at |
4267 | more on top of it. It can be found via gem servers. Its homepage is at |
3146 | <http://rev.rubyforge.org/>. |
4268 | <http://rev.rubyforge.org/>. |
3147 | .Sp |
4269 | .Sp |
3148 | Roger Pack reports that using the link order \f(CW\*(C`\-lws2_32 \-lmsvcrt\-ruby\-190\*(C'\fR |
4270 | Roger Pack reports that using the link order \f(CW\*(C`\-lws2_32 \-lmsvcrt\-ruby\-190\*(C'\fR |
3149 | makes rev work even on mingw. |
4271 | makes rev work even on mingw. |
|
|
4272 | .IP "Haskell" 4 |
|
|
4273 | .IX Item "Haskell" |
|
|
4274 | A haskell binding to libev is available at |
|
|
4275 | http://hackage.haskell.org/cgi\-bin/hackage\-scripts/package/hlibev <http://hackage.haskell.org/cgi-bin/hackage-scripts/package/hlibev>. |
3150 | .IP "D" 4 |
4276 | .IP "D" 4 |
3151 | .IX Item "D" |
4277 | .IX Item "D" |
3152 | Leandro Lucarella has written a D language binding (\fIev.d\fR) for libev, to |
4278 | Leandro Lucarella has written a D language binding (\fIev.d\fR) for libev, to |
3153 | be found at <http://proj.llucax.com.ar/wiki/evd>. |
4279 | be found at <http://www.llucax.com.ar/proj/ev.d/index.html>. |
3154 | .IP "Ocaml" 4 |
4280 | .IP "Ocaml" 4 |
3155 | .IX Item "Ocaml" |
4281 | .IX Item "Ocaml" |
3156 | Erkki Seppala has written Ocaml bindings for libev, to be found at |
4282 | Erkki Seppala has written Ocaml bindings for libev, to be found at |
3157 | <http://modeemi.cs.tut.fi/~flux/software/ocaml\-ev/>. |
4283 | http://modeemi.cs.tut.fi/~flux/software/ocaml\-ev/ <http://modeemi.cs.tut.fi/~flux/software/ocaml-ev/>. |
|
|
4284 | .IP "Lua" 4 |
|
|
4285 | .IX Item "Lua" |
|
|
4286 | Brian Maher has written a partial interface to libev for lua (at the |
|
|
4287 | time of this writing, only \f(CW\*(C`ev_io\*(C'\fR and \f(CW\*(C`ev_timer\*(C'\fR), to be found at |
|
|
4288 | http://github.com/brimworks/lua\-ev <http://github.com/brimworks/lua-ev>. |
3158 | .SH "MACRO MAGIC" |
4289 | .SH "MACRO MAGIC" |
3159 | .IX Header "MACRO MAGIC" |
4290 | .IX Header "MACRO MAGIC" |
3160 | Libev can be compiled with a variety of options, the most fundamental |
4291 | Libev can be compiled with a variety of options, the most fundamental |
3161 | of which is \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. This option determines whether (most) |
4292 | of which is \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. This option determines whether (most) |
3162 | functions and callbacks have an initial \f(CW\*(C`struct ev_loop *\*(C'\fR argument. |
4293 | functions and callbacks have an initial \f(CW\*(C`struct ev_loop *\*(C'\fR argument. |
3163 | .PP |
4294 | .PP |
3164 | To make it easier to write programs that cope with either variant, the |
4295 | To make it easier to write programs that cope with either variant, the |
3165 | following macros are defined: |
4296 | following macros are defined: |
3166 | .ie n .IP """EV_A""\fR, \f(CW""EV_A_""" 4 |
4297 | .ie n .IP """EV_A"", ""EV_A_""" 4 |
3167 | .el .IP "\f(CWEV_A\fR, \f(CWEV_A_\fR" 4 |
4298 | .el .IP "\f(CWEV_A\fR, \f(CWEV_A_\fR" 4 |
3168 | .IX Item "EV_A, EV_A_" |
4299 | .IX Item "EV_A, EV_A_" |
3169 | This provides the loop \fIargument\fR for functions, if one is required (\*(L"ev |
4300 | This provides the loop \fIargument\fR for functions, if one is required (\*(L"ev |
3170 | loop argument\*(R"). The \f(CW\*(C`EV_A\*(C'\fR form is used when this is the sole argument, |
4301 | loop argument\*(R"). The \f(CW\*(C`EV_A\*(C'\fR form is used when this is the sole argument, |
3171 | \&\f(CW\*(C`EV_A_\*(C'\fR is used when other arguments are following. Example: |
4302 | \&\f(CW\*(C`EV_A_\*(C'\fR is used when other arguments are following. Example: |
3172 | .Sp |
4303 | .Sp |
3173 | .Vb 3 |
4304 | .Vb 3 |
3174 | \& ev_unref (EV_A); |
4305 | \& ev_unref (EV_A); |
3175 | \& ev_timer_add (EV_A_ watcher); |
4306 | \& ev_timer_add (EV_A_ watcher); |
3176 | \& ev_loop (EV_A_ 0); |
4307 | \& ev_run (EV_A_ 0); |
3177 | .Ve |
4308 | .Ve |
3178 | .Sp |
4309 | .Sp |
3179 | It assumes the variable \f(CW\*(C`loop\*(C'\fR of type \f(CW\*(C`struct ev_loop *\*(C'\fR is in scope, |
4310 | It assumes the variable \f(CW\*(C`loop\*(C'\fR of type \f(CW\*(C`struct ev_loop *\*(C'\fR is in scope, |
3180 | which is often provided by the following macro. |
4311 | which is often provided by the following macro. |
3181 | .ie n .IP """EV_P""\fR, \f(CW""EV_P_""" 4 |
4312 | .ie n .IP """EV_P"", ""EV_P_""" 4 |
3182 | .el .IP "\f(CWEV_P\fR, \f(CWEV_P_\fR" 4 |
4313 | .el .IP "\f(CWEV_P\fR, \f(CWEV_P_\fR" 4 |
3183 | .IX Item "EV_P, EV_P_" |
4314 | .IX Item "EV_P, EV_P_" |
3184 | This provides the loop \fIparameter\fR for functions, if one is required (\*(L"ev |
4315 | This provides the loop \fIparameter\fR for functions, if one is required (\*(L"ev |
3185 | loop parameter\*(R"). The \f(CW\*(C`EV_P\*(C'\fR form is used when this is the sole parameter, |
4316 | loop parameter\*(R"). The \f(CW\*(C`EV_P\*(C'\fR form is used when this is the sole parameter, |
3186 | \&\f(CW\*(C`EV_P_\*(C'\fR is used when other parameters are following. Example: |
4317 | \&\f(CW\*(C`EV_P_\*(C'\fR is used when other parameters are following. Example: |
… | |
… | |
3193 | \& static void cb (EV_P_ ev_timer *w, int revents) |
4324 | \& static void cb (EV_P_ ev_timer *w, int revents) |
3194 | .Ve |
4325 | .Ve |
3195 | .Sp |
4326 | .Sp |
3196 | It declares a parameter \f(CW\*(C`loop\*(C'\fR of type \f(CW\*(C`struct ev_loop *\*(C'\fR, quite |
4327 | It declares a parameter \f(CW\*(C`loop\*(C'\fR of type \f(CW\*(C`struct ev_loop *\*(C'\fR, quite |
3197 | suitable for use with \f(CW\*(C`EV_A\*(C'\fR. |
4328 | suitable for use with \f(CW\*(C`EV_A\*(C'\fR. |
3198 | .ie n .IP """EV_DEFAULT""\fR, \f(CW""EV_DEFAULT_""" 4 |
4329 | .ie n .IP """EV_DEFAULT"", ""EV_DEFAULT_""" 4 |
3199 | .el .IP "\f(CWEV_DEFAULT\fR, \f(CWEV_DEFAULT_\fR" 4 |
4330 | .el .IP "\f(CWEV_DEFAULT\fR, \f(CWEV_DEFAULT_\fR" 4 |
3200 | .IX Item "EV_DEFAULT, EV_DEFAULT_" |
4331 | .IX Item "EV_DEFAULT, EV_DEFAULT_" |
3201 | Similar to the other two macros, this gives you the value of the default |
4332 | Similar to the other two macros, this gives you the value of the default |
3202 | loop, if multiple loops are supported (\*(L"ev loop default\*(R"). |
4333 | loop, if multiple loops are supported (\*(L"ev loop default\*(R"). The default loop |
|
|
4334 | will be initialised if it isn't already initialised. |
|
|
4335 | .Sp |
|
|
4336 | For non-multiplicity builds, these macros do nothing, so you always have |
|
|
4337 | to initialise the loop somewhere. |
3203 | .ie n .IP """EV_DEFAULT_UC""\fR, \f(CW""EV_DEFAULT_UC_""" 4 |
4338 | .ie n .IP """EV_DEFAULT_UC"", ""EV_DEFAULT_UC_""" 4 |
3204 | .el .IP "\f(CWEV_DEFAULT_UC\fR, \f(CWEV_DEFAULT_UC_\fR" 4 |
4339 | .el .IP "\f(CWEV_DEFAULT_UC\fR, \f(CWEV_DEFAULT_UC_\fR" 4 |
3205 | .IX Item "EV_DEFAULT_UC, EV_DEFAULT_UC_" |
4340 | .IX Item "EV_DEFAULT_UC, EV_DEFAULT_UC_" |
3206 | Usage identical to \f(CW\*(C`EV_DEFAULT\*(C'\fR and \f(CW\*(C`EV_DEFAULT_\*(C'\fR, but requires that the |
4341 | Usage identical to \f(CW\*(C`EV_DEFAULT\*(C'\fR and \f(CW\*(C`EV_DEFAULT_\*(C'\fR, but requires that the |
3207 | default loop has been initialised (\f(CW\*(C`UC\*(C'\fR == unchecked). Their behaviour |
4342 | default loop has been initialised (\f(CW\*(C`UC\*(C'\fR == unchecked). Their behaviour |
3208 | is undefined when the default loop has not been initialised by a previous |
4343 | is undefined when the default loop has not been initialised by a previous |
… | |
… | |
3223 | \& } |
4358 | \& } |
3224 | \& |
4359 | \& |
3225 | \& ev_check check; |
4360 | \& ev_check check; |
3226 | \& ev_check_init (&check, check_cb); |
4361 | \& ev_check_init (&check, check_cb); |
3227 | \& ev_check_start (EV_DEFAULT_ &check); |
4362 | \& ev_check_start (EV_DEFAULT_ &check); |
3228 | \& ev_loop (EV_DEFAULT_ 0); |
4363 | \& ev_run (EV_DEFAULT_ 0); |
3229 | .Ve |
4364 | .Ve |
3230 | .SH "EMBEDDING" |
4365 | .SH "EMBEDDING" |
3231 | .IX Header "EMBEDDING" |
4366 | .IX Header "EMBEDDING" |
3232 | Libev can (and often is) directly embedded into host |
4367 | Libev can (and often is) directly embedded into host |
3233 | applications. Examples of applications that embed it include the Deliantra |
4368 | applications. Examples of applications that embed it include the Deliantra |
… | |
… | |
3236 | .PP |
4371 | .PP |
3237 | The goal is to enable you to just copy the necessary files into your |
4372 | The goal is to enable you to just copy the necessary files into your |
3238 | source directory without having to change even a single line in them, so |
4373 | source directory without having to change even a single line in them, so |
3239 | you can easily upgrade by simply copying (or having a checked-out copy of |
4374 | you can easily upgrade by simply copying (or having a checked-out copy of |
3240 | libev somewhere in your source tree). |
4375 | libev somewhere in your source tree). |
3241 | .Sh "\s-1FILESETS\s0" |
4376 | .SS "\s-1FILESETS\s0" |
3242 | .IX Subsection "FILESETS" |
4377 | .IX Subsection "FILESETS" |
3243 | Depending on what features you need you need to include one or more sets of files |
4378 | Depending on what features you need you need to include one or more sets of files |
3244 | in your application. |
4379 | in your application. |
3245 | .PP |
4380 | .PP |
3246 | \fI\s-1CORE\s0 \s-1EVENT\s0 \s-1LOOP\s0\fR |
4381 | \fI\s-1CORE\s0 \s-1EVENT\s0 \s-1LOOP\s0\fR |
… | |
… | |
3325 | For this of course you need the m4 file: |
4460 | For this of course you need the m4 file: |
3326 | .PP |
4461 | .PP |
3327 | .Vb 1 |
4462 | .Vb 1 |
3328 | \& libev.m4 |
4463 | \& libev.m4 |
3329 | .Ve |
4464 | .Ve |
3330 | .Sh "\s-1PREPROCESSOR\s0 \s-1SYMBOLS/MACROS\s0" |
4465 | .SS "\s-1PREPROCESSOR\s0 \s-1SYMBOLS/MACROS\s0" |
3331 | .IX Subsection "PREPROCESSOR SYMBOLS/MACROS" |
4466 | .IX Subsection "PREPROCESSOR SYMBOLS/MACROS" |
3332 | Libev can be configured via a variety of preprocessor symbols you have to |
4467 | Libev can be configured via a variety of preprocessor symbols you have to |
3333 | define before including any of its files. The default in the absence of |
4468 | define before including (or compiling) any of its files. The default in |
3334 | autoconf is documented for every option. |
4469 | the absence of autoconf is documented for every option. |
|
|
4470 | .PP |
|
|
4471 | Symbols marked with \*(L"(h)\*(R" do not change the \s-1ABI\s0, and can have different |
|
|
4472 | values when compiling libev vs. including \fIev.h\fR, so it is permissible |
|
|
4473 | to redefine them before including \fIev.h\fR without breaking compatibility |
|
|
4474 | to a compiled library. All other symbols change the \s-1ABI\s0, which means all |
|
|
4475 | users of libev and the libev code itself must be compiled with compatible |
|
|
4476 | settings. |
|
|
4477 | .IP "\s-1EV_COMPAT3\s0 (h)" 4 |
|
|
4478 | .IX Item "EV_COMPAT3 (h)" |
|
|
4479 | Backwards compatibility is a major concern for libev. This is why this |
|
|
4480 | release of libev comes with wrappers for the functions and symbols that |
|
|
4481 | have been renamed between libev version 3 and 4. |
|
|
4482 | .Sp |
|
|
4483 | You can disable these wrappers (to test compatibility with future |
|
|
4484 | versions) by defining \f(CW\*(C`EV_COMPAT3\*(C'\fR to \f(CW0\fR when compiling your |
|
|
4485 | sources. This has the additional advantage that you can drop the \f(CW\*(C`struct\*(C'\fR |
|
|
4486 | from \f(CW\*(C`struct ev_loop\*(C'\fR declarations, as libev will provide an \f(CW\*(C`ev_loop\*(C'\fR |
|
|
4487 | typedef in that case. |
|
|
4488 | .Sp |
|
|
4489 | In some future version, the default for \f(CW\*(C`EV_COMPAT3\*(C'\fR will become \f(CW0\fR, |
|
|
4490 | and in some even more future version the compatibility code will be |
|
|
4491 | removed completely. |
3335 | .IP "\s-1EV_STANDALONE\s0" 4 |
4492 | .IP "\s-1EV_STANDALONE\s0 (h)" 4 |
3336 | .IX Item "EV_STANDALONE" |
4493 | .IX Item "EV_STANDALONE (h)" |
3337 | Must always be \f(CW1\fR if you do not use autoconf configuration, which |
4494 | Must always be \f(CW1\fR if you do not use autoconf configuration, which |
3338 | keeps libev from including \fIconfig.h\fR, and it also defines dummy |
4495 | keeps libev from including \fIconfig.h\fR, and it also defines dummy |
3339 | implementations for some libevent functions (such as logging, which is not |
4496 | implementations for some libevent functions (such as logging, which is not |
3340 | supported). It will also not define any of the structs usually found in |
4497 | supported). It will also not define any of the structs usually found in |
3341 | \&\fIevent.h\fR that are not directly supported by the libev core alone. |
4498 | \&\fIevent.h\fR that are not directly supported by the libev core alone. |
3342 | .Sp |
4499 | .Sp |
3343 | In stanbdalone mode, libev will still try to automatically deduce the |
4500 | In standalone mode, libev will still try to automatically deduce the |
3344 | configuration, but has to be more conservative. |
4501 | configuration, but has to be more conservative. |
|
|
4502 | .IP "\s-1EV_USE_FLOOR\s0" 4 |
|
|
4503 | .IX Item "EV_USE_FLOOR" |
|
|
4504 | If defined to be \f(CW1\fR, libev will use the \f(CW\*(C`floor ()\*(C'\fR function for its |
|
|
4505 | periodic reschedule calculations, otherwise libev will fall back on a |
|
|
4506 | portable (slower) implementation. If you enable this, you usually have to |
|
|
4507 | link against libm or something equivalent. Enabling this when the \f(CW\*(C`floor\*(C'\fR |
|
|
4508 | function is not available will fail, so the safe default is to not enable |
|
|
4509 | this. |
3345 | .IP "\s-1EV_USE_MONOTONIC\s0" 4 |
4510 | .IP "\s-1EV_USE_MONOTONIC\s0" 4 |
3346 | .IX Item "EV_USE_MONOTONIC" |
4511 | .IX Item "EV_USE_MONOTONIC" |
3347 | If defined to be \f(CW1\fR, libev will try to detect the availability of the |
4512 | If defined to be \f(CW1\fR, libev will try to detect the availability of the |
3348 | monotonic clock option at both compile time and runtime. Otherwise no |
4513 | monotonic clock option at both compile time and runtime. Otherwise no |
3349 | use of the monotonic clock option will be attempted. If you enable this, |
4514 | use of the monotonic clock option will be attempted. If you enable this, |
… | |
… | |
3352 | to make sure you link against any libraries where the \f(CW\*(C`clock_gettime\*(C'\fR |
4517 | to make sure you link against any libraries where the \f(CW\*(C`clock_gettime\*(C'\fR |
3353 | function is hiding in (often \fI\-lrt\fR). See also \f(CW\*(C`EV_USE_CLOCK_SYSCALL\*(C'\fR. |
4518 | function is hiding in (often \fI\-lrt\fR). See also \f(CW\*(C`EV_USE_CLOCK_SYSCALL\*(C'\fR. |
3354 | .IP "\s-1EV_USE_REALTIME\s0" 4 |
4519 | .IP "\s-1EV_USE_REALTIME\s0" 4 |
3355 | .IX Item "EV_USE_REALTIME" |
4520 | .IX Item "EV_USE_REALTIME" |
3356 | If defined to be \f(CW1\fR, libev will try to detect the availability of the |
4521 | If defined to be \f(CW1\fR, libev will try to detect the availability of the |
3357 | real-time clock option at compile time (and assume its availability at |
4522 | real-time clock option at compile time (and assume its availability |
3358 | runtime if successful). Otherwise no use of the real-time clock option will |
4523 | at runtime if successful). Otherwise no use of the real-time clock |
3359 | be attempted. This effectively replaces \f(CW\*(C`gettimeofday\*(C'\fR by \f(CW\*(C`clock_get |
4524 | option will be attempted. This effectively replaces \f(CW\*(C`gettimeofday\*(C'\fR |
3360 | (CLOCK_REALTIME, ...)\*(C'\fR and will not normally affect correctness. See the |
4525 | by \f(CW\*(C`clock_get (CLOCK_REALTIME, ...)\*(C'\fR and will not normally affect |
3361 | note about libraries in the description of \f(CW\*(C`EV_USE_MONOTONIC\*(C'\fR, though. |
4526 | correctness. See the note about libraries in the description of |
|
|
4527 | \&\f(CW\*(C`EV_USE_MONOTONIC\*(C'\fR, though. Defaults to the opposite value of |
|
|
4528 | \&\f(CW\*(C`EV_USE_CLOCK_SYSCALL\*(C'\fR. |
3362 | .IP "\s-1EV_USE_CLOCK_SYSCALL\s0" 4 |
4529 | .IP "\s-1EV_USE_CLOCK_SYSCALL\s0" 4 |
3363 | .IX Item "EV_USE_CLOCK_SYSCALL" |
4530 | .IX Item "EV_USE_CLOCK_SYSCALL" |
3364 | If defined to be \f(CW1\fR, libev will try to use a direct syscall instead |
4531 | If defined to be \f(CW1\fR, libev will try to use a direct syscall instead |
3365 | of calling the system-provided \f(CW\*(C`clock_gettime\*(C'\fR function. This option |
4532 | of calling the system-provided \f(CW\*(C`clock_gettime\*(C'\fR function. This option |
3366 | 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 |
4533 | 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 |
… | |
… | |
3402 | wants osf handles on win32 (this is the case when the select to |
4569 | wants osf handles on win32 (this is the case when the select to |
3403 | be used is the winsock select). This means that it will call |
4570 | be used is the winsock select). This means that it will call |
3404 | \&\f(CW\*(C`_get_osfhandle\*(C'\fR on the fd to convert it to an \s-1OS\s0 handle. Otherwise, |
4571 | \&\f(CW\*(C`_get_osfhandle\*(C'\fR on the fd to convert it to an \s-1OS\s0 handle. Otherwise, |
3405 | it is assumed that all these functions actually work on fds, even |
4572 | it is assumed that all these functions actually work on fds, even |
3406 | on win32. Should not be defined on non\-win32 platforms. |
4573 | on win32. Should not be defined on non\-win32 platforms. |
3407 | .IP "\s-1EV_FD_TO_WIN32_HANDLE\s0" 4 |
4574 | .IP "\s-1EV_FD_TO_WIN32_HANDLE\s0(fd)" 4 |
3408 | .IX Item "EV_FD_TO_WIN32_HANDLE" |
4575 | .IX Item "EV_FD_TO_WIN32_HANDLE(fd)" |
3409 | If \f(CW\*(C`EV_SELECT_IS_WINSOCKET\*(C'\fR is enabled, then libev needs a way to map |
4576 | If \f(CW\*(C`EV_SELECT_IS_WINSOCKET\*(C'\fR is enabled, then libev needs a way to map |
3410 | file descriptors to socket handles. When not defining this symbol (the |
4577 | file descriptors to socket handles. When not defining this symbol (the |
3411 | default), then libev will call \f(CW\*(C`_get_osfhandle\*(C'\fR, which is usually |
4578 | default), then libev will call \f(CW\*(C`_get_osfhandle\*(C'\fR, which is usually |
3412 | correct. In some cases, programs use their own file descriptor management, |
4579 | correct. In some cases, programs use their own file descriptor management, |
3413 | in which case they can provide this function to map fds to socket handles. |
4580 | in which case they can provide this function to map fds to socket handles. |
|
|
4581 | .IP "\s-1EV_WIN32_HANDLE_TO_FD\s0(handle)" 4 |
|
|
4582 | .IX Item "EV_WIN32_HANDLE_TO_FD(handle)" |
|
|
4583 | If \f(CW\*(C`EV_SELECT_IS_WINSOCKET\*(C'\fR then libev maps handles to file descriptors |
|
|
4584 | using the standard \f(CW\*(C`_open_osfhandle\*(C'\fR function. For programs implementing |
|
|
4585 | their own fd to handle mapping, overwriting this function makes it easier |
|
|
4586 | to do so. This can be done by defining this macro to an appropriate value. |
|
|
4587 | .IP "\s-1EV_WIN32_CLOSE_FD\s0(fd)" 4 |
|
|
4588 | .IX Item "EV_WIN32_CLOSE_FD(fd)" |
|
|
4589 | If programs implement their own fd to handle mapping on win32, then this |
|
|
4590 | macro can be used to override the \f(CW\*(C`close\*(C'\fR function, useful to unregister |
|
|
4591 | file descriptors again. Note that the replacement function has to close |
|
|
4592 | the underlying \s-1OS\s0 handle. |
3414 | .IP "\s-1EV_USE_POLL\s0" 4 |
4593 | .IP "\s-1EV_USE_POLL\s0" 4 |
3415 | .IX Item "EV_USE_POLL" |
4594 | .IX Item "EV_USE_POLL" |
3416 | If defined to be \f(CW1\fR, libev will compile in support for the \f(CW\*(C`poll\*(C'\fR(2) |
4595 | If defined to be \f(CW1\fR, libev will compile in support for the \f(CW\*(C`poll\*(C'\fR(2) |
3417 | backend. Otherwise it will be enabled on non\-win32 platforms. It |
4596 | backend. Otherwise it will be enabled on non\-win32 platforms. It |
3418 | takes precedence over select. |
4597 | takes precedence over select. |
… | |
… | |
3447 | .IX Item "EV_USE_INOTIFY" |
4626 | .IX Item "EV_USE_INOTIFY" |
3448 | If defined to be \f(CW1\fR, libev will compile in support for the Linux inotify |
4627 | If defined to be \f(CW1\fR, libev will compile in support for the Linux inotify |
3449 | interface to speed up \f(CW\*(C`ev_stat\*(C'\fR watchers. Its actual availability will |
4628 | interface to speed up \f(CW\*(C`ev_stat\*(C'\fR watchers. Its actual availability will |
3450 | be detected at runtime. If undefined, it will be enabled if the headers |
4629 | be detected at runtime. If undefined, it will be enabled if the headers |
3451 | indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled. |
4630 | indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled. |
|
|
4631 | .IP "\s-1EV_NO_SMP\s0" 4 |
|
|
4632 | .IX Item "EV_NO_SMP" |
|
|
4633 | If defined to be \f(CW1\fR, libev will assume that memory is always coherent |
|
|
4634 | between threads, that is, threads can be used, but threads never run on |
|
|
4635 | different cpus (or different cpu cores). This reduces dependencies |
|
|
4636 | and makes libev faster. |
|
|
4637 | .IP "\s-1EV_NO_THREADS\s0" 4 |
|
|
4638 | .IX Item "EV_NO_THREADS" |
|
|
4639 | If defined to be \f(CW1\fR, libev will assume that it will never be called |
|
|
4640 | from different threads, which is a stronger assumption than \f(CW\*(C`EV_NO_SMP\*(C'\fR, |
|
|
4641 | above. This reduces dependencies and makes libev faster. |
3452 | .IP "\s-1EV_ATOMIC_T\s0" 4 |
4642 | .IP "\s-1EV_ATOMIC_T\s0" 4 |
3453 | .IX Item "EV_ATOMIC_T" |
4643 | .IX Item "EV_ATOMIC_T" |
3454 | Libev requires an integer type (suitable for storing \f(CW0\fR or \f(CW1\fR) whose |
4644 | Libev requires an integer type (suitable for storing \f(CW0\fR or \f(CW1\fR) whose |
3455 | access is atomic with respect to other threads or signal contexts. No such |
4645 | access is atomic and serialised with respect to other threads or signal |
3456 | type is easily found in the C language, so you can provide your own type |
4646 | contexts. No such type is easily found in the C language, so you can |
3457 | that you know is safe for your purposes. It is used both for signal handler \*(L"locking\*(R" |
4647 | provide your own type that you know is safe for your purposes. It is used |
3458 | as well as for signal and thread safety in \f(CW\*(C`ev_async\*(C'\fR watchers. |
4648 | both for signal handler \*(L"locking\*(R" as well as for signal and thread safety |
|
|
4649 | in \f(CW\*(C`ev_async\*(C'\fR watchers. |
3459 | .Sp |
4650 | .Sp |
3460 | In the absence of this define, libev will use \f(CW\*(C`sig_atomic_t volatile\*(C'\fR |
4651 | In the absence of this define, libev will use \f(CW\*(C`sig_atomic_t volatile\*(C'\fR |
3461 | (from \fIsignal.h\fR), which is usually good enough on most platforms. |
4652 | (from \fIsignal.h\fR), which is usually good enough on most platforms, |
|
|
4653 | although strictly speaking using a type that also implies a memory fence |
|
|
4654 | is required. |
3462 | .IP "\s-1EV_H\s0" 4 |
4655 | .IP "\s-1EV_H\s0 (h)" 4 |
3463 | .IX Item "EV_H" |
4656 | .IX Item "EV_H (h)" |
3464 | The name of the \fIev.h\fR header file used to include it. The default if |
4657 | The name of the \fIev.h\fR header file used to include it. The default if |
3465 | undefined is \f(CW"ev.h"\fR in \fIevent.h\fR, \fIev.c\fR and \fIev++.h\fR. This can be |
4658 | undefined is \f(CW"ev.h"\fR in \fIevent.h\fR, \fIev.c\fR and \fIev++.h\fR. This can be |
3466 | used to virtually rename the \fIev.h\fR header file in case of conflicts. |
4659 | used to virtually rename the \fIev.h\fR header file in case of conflicts. |
3467 | .IP "\s-1EV_CONFIG_H\s0" 4 |
4660 | .IP "\s-1EV_CONFIG_H\s0 (h)" 4 |
3468 | .IX Item "EV_CONFIG_H" |
4661 | .IX Item "EV_CONFIG_H (h)" |
3469 | If \f(CW\*(C`EV_STANDALONE\*(C'\fR isn't \f(CW1\fR, this variable can be used to override |
4662 | If \f(CW\*(C`EV_STANDALONE\*(C'\fR isn't \f(CW1\fR, this variable can be used to override |
3470 | \&\fIev.c\fR's idea of where to find the \fIconfig.h\fR file, similarly to |
4663 | \&\fIev.c\fR's idea of where to find the \fIconfig.h\fR file, similarly to |
3471 | \&\f(CW\*(C`EV_H\*(C'\fR, above. |
4664 | \&\f(CW\*(C`EV_H\*(C'\fR, above. |
3472 | .IP "\s-1EV_EVENT_H\s0" 4 |
4665 | .IP "\s-1EV_EVENT_H\s0 (h)" 4 |
3473 | .IX Item "EV_EVENT_H" |
4666 | .IX Item "EV_EVENT_H (h)" |
3474 | Similarly to \f(CW\*(C`EV_H\*(C'\fR, this macro can be used to override \fIevent.c\fR's idea |
4667 | Similarly to \f(CW\*(C`EV_H\*(C'\fR, this macro can be used to override \fIevent.c\fR's idea |
3475 | of how the \fIevent.h\fR header can be found, the default is \f(CW"event.h"\fR. |
4668 | of how the \fIevent.h\fR header can be found, the default is \f(CW"event.h"\fR. |
3476 | .IP "\s-1EV_PROTOTYPES\s0" 4 |
4669 | .IP "\s-1EV_PROTOTYPES\s0 (h)" 4 |
3477 | .IX Item "EV_PROTOTYPES" |
4670 | .IX Item "EV_PROTOTYPES (h)" |
3478 | If defined to be \f(CW0\fR, then \fIev.h\fR will not define any function |
4671 | If defined to be \f(CW0\fR, then \fIev.h\fR will not define any function |
3479 | prototypes, but still define all the structs and other symbols. This is |
4672 | prototypes, but still define all the structs and other symbols. This is |
3480 | occasionally useful if you want to provide your own wrapper functions |
4673 | occasionally useful if you want to provide your own wrapper functions |
3481 | around libev functions. |
4674 | around libev functions. |
3482 | .IP "\s-1EV_MULTIPLICITY\s0" 4 |
4675 | .IP "\s-1EV_MULTIPLICITY\s0" 4 |
… | |
… | |
3484 | If undefined or defined to \f(CW1\fR, then all event-loop-specific functions |
4677 | If undefined or defined to \f(CW1\fR, then all event-loop-specific functions |
3485 | will have the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument, and you can create |
4678 | will have the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument, and you can create |
3486 | additional independent event loops. Otherwise there will be no support |
4679 | additional independent event loops. Otherwise there will be no support |
3487 | for multiple event loops and there is no first event loop pointer |
4680 | for multiple event loops and there is no first event loop pointer |
3488 | argument. Instead, all functions act on the single default loop. |
4681 | argument. Instead, all functions act on the single default loop. |
|
|
4682 | .Sp |
|
|
4683 | Note that \f(CW\*(C`EV_DEFAULT\*(C'\fR and \f(CW\*(C`EV_DEFAULT_\*(C'\fR will no longer provide a |
|
|
4684 | default loop when multiplicity is switched off \- you always have to |
|
|
4685 | initialise the loop manually in this case. |
3489 | .IP "\s-1EV_MINPRI\s0" 4 |
4686 | .IP "\s-1EV_MINPRI\s0" 4 |
3490 | .IX Item "EV_MINPRI" |
4687 | .IX Item "EV_MINPRI" |
3491 | .PD 0 |
4688 | .PD 0 |
3492 | .IP "\s-1EV_MAXPRI\s0" 4 |
4689 | .IP "\s-1EV_MAXPRI\s0" 4 |
3493 | .IX Item "EV_MAXPRI" |
4690 | .IX Item "EV_MAXPRI" |
… | |
… | |
3502 | and time, so using the defaults of five priorities (\-2 .. +2) is usually |
4699 | and time, so using the defaults of five priorities (\-2 .. +2) is usually |
3503 | fine. |
4700 | fine. |
3504 | .Sp |
4701 | .Sp |
3505 | If your embedding application does not need any priorities, defining these |
4702 | If your embedding application does not need any priorities, defining these |
3506 | both to \f(CW0\fR will save some memory and \s-1CPU\s0. |
4703 | both to \f(CW0\fR will save some memory and \s-1CPU\s0. |
3507 | .IP "\s-1EV_PERIODIC_ENABLE\s0" 4 |
4704 | .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 |
3508 | .IX Item "EV_PERIODIC_ENABLE" |
4705 | .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." |
3509 | If undefined or defined to be \f(CW1\fR, then periodic timers are supported. If |
4706 | If undefined or defined to be \f(CW1\fR (and the platform supports it), then |
3510 | defined to be \f(CW0\fR, then they are not. Disabling them saves a few kB of |
4707 | the respective watcher type is supported. If defined to be \f(CW0\fR, then it |
3511 | code. |
4708 | is not. Disabling watcher types mainly saves code size. |
3512 | .IP "\s-1EV_IDLE_ENABLE\s0" 4 |
|
|
3513 | .IX Item "EV_IDLE_ENABLE" |
|
|
3514 | If undefined or defined to be \f(CW1\fR, then idle watchers are supported. If |
|
|
3515 | defined to be \f(CW0\fR, then they are not. Disabling them saves a few kB of |
|
|
3516 | code. |
|
|
3517 | .IP "\s-1EV_EMBED_ENABLE\s0" 4 |
|
|
3518 | .IX Item "EV_EMBED_ENABLE" |
|
|
3519 | If undefined or defined to be \f(CW1\fR, then embed watchers are supported. If |
|
|
3520 | defined to be \f(CW0\fR, then they are not. Embed watchers rely on most other |
|
|
3521 | watcher types, which therefore must not be disabled. |
|
|
3522 | .IP "\s-1EV_STAT_ENABLE\s0" 4 |
4709 | .IP "\s-1EV_FEATURES\s0" 4 |
3523 | .IX Item "EV_STAT_ENABLE" |
4710 | .IX Item "EV_FEATURES" |
3524 | If undefined or defined to be \f(CW1\fR, then stat watchers are supported. If |
|
|
3525 | defined to be \f(CW0\fR, then they are not. |
|
|
3526 | .IP "\s-1EV_FORK_ENABLE\s0" 4 |
|
|
3527 | .IX Item "EV_FORK_ENABLE" |
|
|
3528 | If undefined or defined to be \f(CW1\fR, then fork watchers are supported. If |
|
|
3529 | defined to be \f(CW0\fR, then they are not. |
|
|
3530 | .IP "\s-1EV_ASYNC_ENABLE\s0" 4 |
|
|
3531 | .IX Item "EV_ASYNC_ENABLE" |
|
|
3532 | If undefined or defined to be \f(CW1\fR, then async watchers are supported. If |
|
|
3533 | defined to be \f(CW0\fR, then they are not. |
|
|
3534 | .IP "\s-1EV_MINIMAL\s0" 4 |
|
|
3535 | .IX Item "EV_MINIMAL" |
|
|
3536 | If you need to shave off some kilobytes of code at the expense of some |
4711 | If you need to shave off some kilobytes of code at the expense of some |
3537 | speed, define this symbol to \f(CW1\fR. Currently this is used to override some |
4712 | speed (but with the full \s-1API\s0), you can define this symbol to request |
3538 | inlining decisions, saves roughly 30% code size on amd64. It also selects a |
4713 | certain subsets of functionality. The default is to enable all features |
3539 | much smaller 2\-heap for timer management over the default 4\-heap. |
4714 | that can be enabled on the platform. |
|
|
4715 | .Sp |
|
|
4716 | A typical way to use this symbol is to define it to \f(CW0\fR (or to a bitset |
|
|
4717 | with some broad features you want) and then selectively re-enable |
|
|
4718 | additional parts you want, for example if you want everything minimal, |
|
|
4719 | but multiple event loop support, async and child watchers and the poll |
|
|
4720 | backend, use this: |
|
|
4721 | .Sp |
|
|
4722 | .Vb 5 |
|
|
4723 | \& #define EV_FEATURES 0 |
|
|
4724 | \& #define EV_MULTIPLICITY 1 |
|
|
4725 | \& #define EV_USE_POLL 1 |
|
|
4726 | \& #define EV_CHILD_ENABLE 1 |
|
|
4727 | \& #define EV_ASYNC_ENABLE 1 |
|
|
4728 | .Ve |
|
|
4729 | .Sp |
|
|
4730 | The actual value is a bitset, it can be a combination of the following |
|
|
4731 | values: |
|
|
4732 | .RS 4 |
|
|
4733 | .ie n .IP "1 \- faster/larger code" 4 |
|
|
4734 | .el .IP "\f(CW1\fR \- faster/larger code" 4 |
|
|
4735 | .IX Item "1 - faster/larger code" |
|
|
4736 | Use larger code to speed up some operations. |
|
|
4737 | .Sp |
|
|
4738 | Currently this is used to override some inlining decisions (enlarging the |
|
|
4739 | code size by roughly 30% on amd64). |
|
|
4740 | .Sp |
|
|
4741 | When optimising for size, use of compiler flags such as \f(CW\*(C`\-Os\*(C'\fR with |
|
|
4742 | gcc is recommended, as well as \f(CW\*(C`\-DNDEBUG\*(C'\fR, as libev contains a number of |
|
|
4743 | assertions. |
|
|
4744 | .ie n .IP "2 \- faster/larger data structures" 4 |
|
|
4745 | .el .IP "\f(CW2\fR \- faster/larger data structures" 4 |
|
|
4746 | .IX Item "2 - faster/larger data structures" |
|
|
4747 | Replaces the small 2\-heap for timer management by a faster 4\-heap, larger |
|
|
4748 | hash table sizes and so on. This will usually further increase code size |
|
|
4749 | and can additionally have an effect on the size of data structures at |
|
|
4750 | runtime. |
|
|
4751 | .ie n .IP "4 \- full \s-1API\s0 configuration" 4 |
|
|
4752 | .el .IP "\f(CW4\fR \- full \s-1API\s0 configuration" 4 |
|
|
4753 | .IX Item "4 - full API configuration" |
|
|
4754 | This enables priorities (sets \f(CW\*(C`EV_MAXPRI\*(C'\fR=2 and \f(CW\*(C`EV_MINPRI\*(C'\fR=\-2), and |
|
|
4755 | enables multiplicity (\f(CW\*(C`EV_MULTIPLICITY\*(C'\fR=1). |
|
|
4756 | .ie n .IP "8 \- full \s-1API\s0" 4 |
|
|
4757 | .el .IP "\f(CW8\fR \- full \s-1API\s0" 4 |
|
|
4758 | .IX Item "8 - full API" |
|
|
4759 | This enables a lot of the \*(L"lesser used\*(R" \s-1API\s0 functions. See \f(CW\*(C`ev.h\*(C'\fR for |
|
|
4760 | details on which parts of the \s-1API\s0 are still available without this |
|
|
4761 | feature, and do not complain if this subset changes over time. |
|
|
4762 | .ie n .IP "16 \- enable all optional watcher types" 4 |
|
|
4763 | .el .IP "\f(CW16\fR \- enable all optional watcher types" 4 |
|
|
4764 | .IX Item "16 - enable all optional watcher types" |
|
|
4765 | Enables all optional watcher types. If you want to selectively enable |
|
|
4766 | only some watcher types other than I/O and timers (e.g. prepare, |
|
|
4767 | embed, async, child...) you can enable them manually by defining |
|
|
4768 | \&\f(CW\*(C`EV_watchertype_ENABLE\*(C'\fR to \f(CW1\fR instead. |
|
|
4769 | .ie n .IP "32 \- enable all backends" 4 |
|
|
4770 | .el .IP "\f(CW32\fR \- enable all backends" 4 |
|
|
4771 | .IX Item "32 - enable all backends" |
|
|
4772 | This enables all backends \- without this feature, you need to enable at |
|
|
4773 | least one backend manually (\f(CW\*(C`EV_USE_SELECT\*(C'\fR is a good choice). |
|
|
4774 | .ie n .IP "64 \- enable OS-specific ""helper"" APIs" 4 |
|
|
4775 | .el .IP "\f(CW64\fR \- enable OS-specific ``helper'' APIs" 4 |
|
|
4776 | .IX Item "64 - enable OS-specific helper APIs" |
|
|
4777 | Enable inotify, eventfd, signalfd and similar OS-specific helper APIs by |
|
|
4778 | default. |
|
|
4779 | .RE |
|
|
4780 | .RS 4 |
|
|
4781 | .Sp |
|
|
4782 | Compiling with \f(CW\*(C`gcc \-Os \-DEV_STANDALONE \-DEV_USE_EPOLL=1 \-DEV_FEATURES=0\*(C'\fR |
|
|
4783 | reduces the compiled size of libev from 24.7Kb code/2.8Kb data to 6.5Kb |
|
|
4784 | code/0.3Kb data on my GNU/Linux amd64 system, while still giving you I/O |
|
|
4785 | watchers, timers and monotonic clock support. |
|
|
4786 | .Sp |
|
|
4787 | With an intelligent-enough linker (gcc+binutils are intelligent enough |
|
|
4788 | when you use \f(CW\*(C`\-Wl,\-\-gc\-sections \-ffunction\-sections\*(C'\fR) functions unused by |
|
|
4789 | your program might be left out as well \- a binary starting a timer and an |
|
|
4790 | I/O watcher then might come out at only 5Kb. |
|
|
4791 | .RE |
|
|
4792 | .IP "\s-1EV_API_STATIC\s0" 4 |
|
|
4793 | .IX Item "EV_API_STATIC" |
|
|
4794 | If this symbol is defined (by default it is not), then all identifiers |
|
|
4795 | will have static linkage. This means that libev will not export any |
|
|
4796 | identifiers, and you cannot link against libev anymore. This can be useful |
|
|
4797 | when you embed libev, only want to use libev functions in a single file, |
|
|
4798 | and do not want its identifiers to be visible. |
|
|
4799 | .Sp |
|
|
4800 | To use this, define \f(CW\*(C`EV_API_STATIC\*(C'\fR and include \fIev.c\fR in the file that |
|
|
4801 | wants to use libev. |
|
|
4802 | .Sp |
|
|
4803 | This option only works when libev is compiled with a C compiler, as \*(C+ |
|
|
4804 | doesn't support the required declaration syntax. |
|
|
4805 | .IP "\s-1EV_AVOID_STDIO\s0" 4 |
|
|
4806 | .IX Item "EV_AVOID_STDIO" |
|
|
4807 | If this is set to \f(CW1\fR at compiletime, then libev will avoid using stdio |
|
|
4808 | functions (printf, scanf, perror etc.). This will increase the code size |
|
|
4809 | somewhat, but if your program doesn't otherwise depend on stdio and your |
|
|
4810 | libc allows it, this avoids linking in the stdio library which is quite |
|
|
4811 | big. |
|
|
4812 | .Sp |
|
|
4813 | Note that error messages might become less precise when this option is |
|
|
4814 | enabled. |
|
|
4815 | .IP "\s-1EV_NSIG\s0" 4 |
|
|
4816 | .IX Item "EV_NSIG" |
|
|
4817 | The highest supported signal number, +1 (or, the number of |
|
|
4818 | signals): Normally, libev tries to deduce the maximum number of signals |
|
|
4819 | automatically, but sometimes this fails, in which case it can be |
|
|
4820 | specified. Also, using a lower number than detected (\f(CW32\fR should be |
|
|
4821 | good for about any system in existence) can save some memory, as libev |
|
|
4822 | statically allocates some 12\-24 bytes per signal number. |
3540 | .IP "\s-1EV_PID_HASHSIZE\s0" 4 |
4823 | .IP "\s-1EV_PID_HASHSIZE\s0" 4 |
3541 | .IX Item "EV_PID_HASHSIZE" |
4824 | .IX Item "EV_PID_HASHSIZE" |
3542 | \&\f(CW\*(C`ev_child\*(C'\fR watchers use a small hash table to distribute workload by |
4825 | \&\f(CW\*(C`ev_child\*(C'\fR watchers use a small hash table to distribute workload by |
3543 | pid. The default size is \f(CW16\fR (or \f(CW1\fR with \f(CW\*(C`EV_MINIMAL\*(C'\fR), usually more |
4826 | pid. The default size is \f(CW16\fR (or \f(CW1\fR with \f(CW\*(C`EV_FEATURES\*(C'\fR disabled), |
3544 | than enough. If you need to manage thousands of children you might want to |
4827 | usually more than enough. If you need to manage thousands of children you |
3545 | increase this value (\fImust\fR be a power of two). |
4828 | might want to increase this value (\fImust\fR be a power of two). |
3546 | .IP "\s-1EV_INOTIFY_HASHSIZE\s0" 4 |
4829 | .IP "\s-1EV_INOTIFY_HASHSIZE\s0" 4 |
3547 | .IX Item "EV_INOTIFY_HASHSIZE" |
4830 | .IX Item "EV_INOTIFY_HASHSIZE" |
3548 | \&\f(CW\*(C`ev_stat\*(C'\fR watchers use a small hash table to distribute workload by |
4831 | \&\f(CW\*(C`ev_stat\*(C'\fR watchers use a small hash table to distribute workload by |
3549 | inotify watch id. The default size is \f(CW16\fR (or \f(CW1\fR with \f(CW\*(C`EV_MINIMAL\*(C'\fR), |
4832 | inotify watch id. The default size is \f(CW16\fR (or \f(CW1\fR with \f(CW\*(C`EV_FEATURES\*(C'\fR |
3550 | usually more than enough. If you need to manage thousands of \f(CW\*(C`ev_stat\*(C'\fR |
4833 | disabled), usually more than enough. If you need to manage thousands of |
3551 | watchers you might want to increase this value (\fImust\fR be a power of |
4834 | \&\f(CW\*(C`ev_stat\*(C'\fR watchers you might want to increase this value (\fImust\fR be a |
3552 | two). |
4835 | power of two). |
3553 | .IP "\s-1EV_USE_4HEAP\s0" 4 |
4836 | .IP "\s-1EV_USE_4HEAP\s0" 4 |
3554 | .IX Item "EV_USE_4HEAP" |
4837 | .IX Item "EV_USE_4HEAP" |
3555 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
4838 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
3556 | timer and periodics heaps, libev uses a 4\-heap when this symbol is defined |
4839 | timer and periodics heaps, libev uses a 4\-heap when this symbol is defined |
3557 | to \f(CW1\fR. The 4\-heap uses more complicated (longer) code but has noticeably |
4840 | to \f(CW1\fR. The 4\-heap uses more complicated (longer) code but has noticeably |
3558 | faster performance with many (thousands) of watchers. |
4841 | faster performance with many (thousands) of watchers. |
3559 | .Sp |
4842 | .Sp |
3560 | The default is \f(CW1\fR unless \f(CW\*(C`EV_MINIMAL\*(C'\fR is set in which case it is \f(CW0\fR |
4843 | The default is \f(CW1\fR, unless \f(CW\*(C`EV_FEATURES\*(C'\fR overrides it, in which case it |
3561 | (disabled). |
4844 | will be \f(CW0\fR. |
3562 | .IP "\s-1EV_HEAP_CACHE_AT\s0" 4 |
4845 | .IP "\s-1EV_HEAP_CACHE_AT\s0" 4 |
3563 | .IX Item "EV_HEAP_CACHE_AT" |
4846 | .IX Item "EV_HEAP_CACHE_AT" |
3564 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
4847 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
3565 | timer and periodics heaps, libev can cache the timestamp (\fIat\fR) within |
4848 | timer and periodics heaps, libev can cache the timestamp (\fIat\fR) within |
3566 | the heap structure (selected by defining \f(CW\*(C`EV_HEAP_CACHE_AT\*(C'\fR to \f(CW1\fR), |
4849 | the heap structure (selected by defining \f(CW\*(C`EV_HEAP_CACHE_AT\*(C'\fR to \f(CW1\fR), |
3567 | which uses 8\-12 bytes more per watcher and a few hundred bytes more code, |
4850 | which uses 8\-12 bytes more per watcher and a few hundred bytes more code, |
3568 | but avoids random read accesses on heap changes. This improves performance |
4851 | but avoids random read accesses on heap changes. This improves performance |
3569 | noticeably with many (hundreds) of watchers. |
4852 | noticeably with many (hundreds) of watchers. |
3570 | .Sp |
4853 | .Sp |
3571 | The default is \f(CW1\fR unless \f(CW\*(C`EV_MINIMAL\*(C'\fR is set in which case it is \f(CW0\fR |
4854 | The default is \f(CW1\fR, unless \f(CW\*(C`EV_FEATURES\*(C'\fR overrides it, in which case it |
3572 | (disabled). |
4855 | will be \f(CW0\fR. |
3573 | .IP "\s-1EV_VERIFY\s0" 4 |
4856 | .IP "\s-1EV_VERIFY\s0" 4 |
3574 | .IX Item "EV_VERIFY" |
4857 | .IX Item "EV_VERIFY" |
3575 | Controls how much internal verification (see \f(CW\*(C`ev_loop_verify ()\*(C'\fR) will |
4858 | Controls how much internal verification (see \f(CW\*(C`ev_verify ()\*(C'\fR) will |
3576 | be done: If set to \f(CW0\fR, no internal verification code will be compiled |
4859 | be done: If set to \f(CW0\fR, no internal verification code will be compiled |
3577 | in. If set to \f(CW1\fR, then verification code will be compiled in, but not |
4860 | in. If set to \f(CW1\fR, then verification code will be compiled in, but not |
3578 | called. If set to \f(CW2\fR, then the internal verification code will be |
4861 | called. If set to \f(CW2\fR, then the internal verification code will be |
3579 | called once per loop, which can slow down libev. If set to \f(CW3\fR, then the |
4862 | called once per loop, which can slow down libev. If set to \f(CW3\fR, then the |
3580 | verification code will be called very frequently, which will slow down |
4863 | verification code will be called very frequently, which will slow down |
3581 | libev considerably. |
4864 | libev considerably. |
3582 | .Sp |
4865 | .Sp |
3583 | The default is \f(CW1\fR, unless \f(CW\*(C`EV_MINIMAL\*(C'\fR is set, in which case it will be |
4866 | The default is \f(CW1\fR, unless \f(CW\*(C`EV_FEATURES\*(C'\fR overrides it, in which case it |
3584 | \&\f(CW0\fR. |
4867 | will be \f(CW0\fR. |
3585 | .IP "\s-1EV_COMMON\s0" 4 |
4868 | .IP "\s-1EV_COMMON\s0" 4 |
3586 | .IX Item "EV_COMMON" |
4869 | .IX Item "EV_COMMON" |
3587 | By default, all watchers have a \f(CW\*(C`void *data\*(C'\fR member. By redefining |
4870 | By default, all watchers have a \f(CW\*(C`void *data\*(C'\fR member. By redefining |
3588 | this macro to a something else you can include more and other types of |
4871 | this macro to something else you can include more and other types of |
3589 | members. You have to define it each time you include one of the files, |
4872 | members. You have to define it each time you include one of the files, |
3590 | though, and it must be identical each time. |
4873 | though, and it must be identical each time. |
3591 | .Sp |
4874 | .Sp |
3592 | For example, the perl \s-1EV\s0 module uses something like this: |
4875 | For example, the perl \s-1EV\s0 module uses something like this: |
3593 | .Sp |
4876 | .Sp |
… | |
… | |
3608 | and the way callbacks are invoked and set. Must expand to a struct member |
4891 | and the way callbacks are invoked and set. Must expand to a struct member |
3609 | definition and a statement, respectively. See the \fIev.h\fR header file for |
4892 | definition and a statement, respectively. See the \fIev.h\fR header file for |
3610 | their default definitions. One possible use for overriding these is to |
4893 | their default definitions. One possible use for overriding these is to |
3611 | avoid the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument in all cases, or to use |
4894 | avoid the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument in all cases, or to use |
3612 | method calls instead of plain function calls in \*(C+. |
4895 | method calls instead of plain function calls in \*(C+. |
3613 | .Sh "\s-1EXPORTED\s0 \s-1API\s0 \s-1SYMBOLS\s0" |
4896 | .SS "\s-1EXPORTED\s0 \s-1API\s0 \s-1SYMBOLS\s0" |
3614 | .IX Subsection "EXPORTED API SYMBOLS" |
4897 | .IX Subsection "EXPORTED API SYMBOLS" |
3615 | If you need to re-export the \s-1API\s0 (e.g. via a \s-1DLL\s0) and you need a list of |
4898 | If you need to re-export the \s-1API\s0 (e.g. via a \s-1DLL\s0) and you need a list of |
3616 | exported symbols, you can use the provided \fISymbol.*\fR files which list |
4899 | exported symbols, you can use the provided \fISymbol.*\fR files which list |
3617 | all public symbols, one per line: |
4900 | all public symbols, one per line: |
3618 | .PP |
4901 | .PP |
… | |
… | |
3638 | \& #define ev_backend myprefix_ev_backend |
4921 | \& #define ev_backend myprefix_ev_backend |
3639 | \& #define ev_check_start myprefix_ev_check_start |
4922 | \& #define ev_check_start myprefix_ev_check_start |
3640 | \& #define ev_check_stop myprefix_ev_check_stop |
4923 | \& #define ev_check_stop myprefix_ev_check_stop |
3641 | \& ... |
4924 | \& ... |
3642 | .Ve |
4925 | .Ve |
3643 | .Sh "\s-1EXAMPLES\s0" |
4926 | .SS "\s-1EXAMPLES\s0" |
3644 | .IX Subsection "EXAMPLES" |
4927 | .IX Subsection "EXAMPLES" |
3645 | For a real-world example of a program the includes libev |
4928 | For a real-world example of a program the includes libev |
3646 | verbatim, you can have a look at the \s-1EV\s0 perl module |
4929 | verbatim, you can have a look at the \s-1EV\s0 perl module |
3647 | (<http://software.schmorp.de/pkg/EV.html>). It has the libev files in |
4930 | (<http://software.schmorp.de/pkg/EV.html>). It has the libev files in |
3648 | the \fIlibev/\fR subdirectory and includes them in the \fI\s-1EV/EVAPI\s0.h\fR (public |
4931 | the \fIlibev/\fR subdirectory and includes them in the \fI\s-1EV/EVAPI\s0.h\fR (public |
… | |
… | |
3651 | file. |
4934 | file. |
3652 | .PP |
4935 | .PP |
3653 | The usage in rxvt-unicode is simpler. It has a \fIev_cpp.h\fR header file |
4936 | The usage in rxvt-unicode is simpler. It has a \fIev_cpp.h\fR header file |
3654 | that everybody includes and which overrides some configure choices: |
4937 | that everybody includes and which overrides some configure choices: |
3655 | .PP |
4938 | .PP |
3656 | .Vb 9 |
4939 | .Vb 8 |
3657 | \& #define EV_MINIMAL 1 |
4940 | \& #define EV_FEATURES 8 |
3658 | \& #define EV_USE_POLL 0 |
4941 | \& #define EV_USE_SELECT 1 |
3659 | \& #define EV_MULTIPLICITY 0 |
|
|
3660 | \& #define EV_PERIODIC_ENABLE 0 |
4942 | \& #define EV_PREPARE_ENABLE 1 |
|
|
4943 | \& #define EV_IDLE_ENABLE 1 |
3661 | \& #define EV_STAT_ENABLE 0 |
4944 | \& #define EV_SIGNAL_ENABLE 1 |
3662 | \& #define EV_FORK_ENABLE 0 |
4945 | \& #define EV_CHILD_ENABLE 1 |
|
|
4946 | \& #define EV_USE_STDEXCEPT 0 |
3663 | \& #define EV_CONFIG_H <config.h> |
4947 | \& #define EV_CONFIG_H <config.h> |
3664 | \& #define EV_MINPRI 0 |
|
|
3665 | \& #define EV_MAXPRI 0 |
|
|
3666 | \& |
4948 | \& |
3667 | \& #include "ev++.h" |
4949 | \& #include "ev++.h" |
3668 | .Ve |
4950 | .Ve |
3669 | .PP |
4951 | .PP |
3670 | And a \fIev_cpp.C\fR implementation file that contains libev proper and is compiled: |
4952 | And a \fIev_cpp.C\fR implementation file that contains libev proper and is compiled: |
3671 | .PP |
4953 | .PP |
3672 | .Vb 2 |
4954 | .Vb 2 |
3673 | \& #include "ev_cpp.h" |
4955 | \& #include "ev_cpp.h" |
3674 | \& #include "ev.c" |
4956 | \& #include "ev.c" |
3675 | .Ve |
4957 | .Ve |
3676 | .SH "INTERACTION WITH OTHER PROGRAMS OR LIBRARIES" |
4958 | .SH "INTERACTION WITH OTHER PROGRAMS, LIBRARIES OR THE ENVIRONMENT" |
3677 | .IX Header "INTERACTION WITH OTHER PROGRAMS OR LIBRARIES" |
4959 | .IX Header "INTERACTION WITH OTHER PROGRAMS, LIBRARIES OR THE ENVIRONMENT" |
3678 | .Sh "\s-1THREADS\s0 \s-1AND\s0 \s-1COROUTINES\s0" |
4960 | .SS "\s-1THREADS\s0 \s-1AND\s0 \s-1COROUTINES\s0" |
3679 | .IX Subsection "THREADS AND COROUTINES" |
4961 | .IX Subsection "THREADS AND COROUTINES" |
3680 | \fI\s-1THREADS\s0\fR |
4962 | \fI\s-1THREADS\s0\fR |
3681 | .IX Subsection "THREADS" |
4963 | .IX Subsection "THREADS" |
3682 | .PP |
4964 | .PP |
3683 | All libev functions are reentrant and thread-safe unless explicitly |
4965 | All libev functions are reentrant and thread-safe unless explicitly |
… | |
… | |
3729 | An example use would be to communicate signals or other events that only |
5011 | An example use would be to communicate signals or other events that only |
3730 | work in the default loop by registering the signal watcher with the |
5012 | work in the default loop by registering the signal watcher with the |
3731 | default loop and triggering an \f(CW\*(C`ev_async\*(C'\fR watcher from the default loop |
5013 | default loop and triggering an \f(CW\*(C`ev_async\*(C'\fR watcher from the default loop |
3732 | watcher callback into the event loop interested in the signal. |
5014 | watcher callback into the event loop interested in the signal. |
3733 | .PP |
5015 | .PP |
|
|
5016 | See also \*(L"\s-1THREAD\s0 \s-1LOCKING\s0 \s-1EXAMPLE\s0\*(R". |
|
|
5017 | .PP |
3734 | \fI\s-1COROUTINES\s0\fR |
5018 | \fI\s-1COROUTINES\s0\fR |
3735 | .IX Subsection "COROUTINES" |
5019 | .IX Subsection "COROUTINES" |
3736 | .PP |
5020 | .PP |
3737 | Libev is very accommodating to coroutines (\*(L"cooperative threads\*(R"): |
5021 | Libev is very accommodating to coroutines (\*(L"cooperative threads\*(R"): |
3738 | libev fully supports nesting calls to its functions from different |
5022 | libev fully supports nesting calls to its functions from different |
3739 | coroutines (e.g. you can call \f(CW\*(C`ev_loop\*(C'\fR on the same loop from two |
5023 | coroutines (e.g. you can call \f(CW\*(C`ev_run\*(C'\fR on the same loop from two |
3740 | different coroutines, and switch freely between both coroutines running the |
5024 | different coroutines, and switch freely between both coroutines running |
3741 | loop, as long as you don't confuse yourself). The only exception is that |
5025 | the loop, as long as you don't confuse yourself). The only exception is |
3742 | you must not do this from \f(CW\*(C`ev_periodic\*(C'\fR reschedule callbacks. |
5026 | that you must not do this from \f(CW\*(C`ev_periodic\*(C'\fR reschedule callbacks. |
3743 | .PP |
5027 | .PP |
3744 | Care has been taken to ensure that libev does not keep local state inside |
5028 | Care has been taken to ensure that libev does not keep local state inside |
3745 | \&\f(CW\*(C`ev_loop\*(C'\fR, and other calls do not usually allow for coroutine switches as |
5029 | \&\f(CW\*(C`ev_run\*(C'\fR, and other calls do not usually allow for coroutine switches as |
3746 | they do not call any callbacks. |
5030 | they do not call any callbacks. |
3747 | .Sh "\s-1COMPILER\s0 \s-1WARNINGS\s0" |
5031 | .SS "\s-1COMPILER\s0 \s-1WARNINGS\s0" |
3748 | .IX Subsection "COMPILER WARNINGS" |
5032 | .IX Subsection "COMPILER WARNINGS" |
3749 | Depending on your compiler and compiler settings, you might get no or a |
5033 | Depending on your compiler and compiler settings, you might get no or a |
3750 | lot of warnings when compiling libev code. Some people are apparently |
5034 | lot of warnings when compiling libev code. Some people are apparently |
3751 | scared by this. |
5035 | scared by this. |
3752 | .PP |
5036 | .PP |
… | |
… | |
3760 | maintainable. |
5044 | maintainable. |
3761 | .PP |
5045 | .PP |
3762 | And of course, some compiler warnings are just plain stupid, or simply |
5046 | And of course, some compiler warnings are just plain stupid, or simply |
3763 | wrong (because they don't actually warn about the condition their message |
5047 | wrong (because they don't actually warn about the condition their message |
3764 | seems to warn about). For example, certain older gcc versions had some |
5048 | seems to warn about). For example, certain older gcc versions had some |
3765 | warnings that resulted an extreme number of false positives. These have |
5049 | warnings that resulted in an extreme number of false positives. These have |
3766 | been fixed, but some people still insist on making code warn-free with |
5050 | been fixed, but some people still insist on making code warn-free with |
3767 | such buggy versions. |
5051 | such buggy versions. |
3768 | .PP |
5052 | .PP |
3769 | While libev is written to generate as few warnings as possible, |
5053 | While libev is written to generate as few warnings as possible, |
3770 | \&\*(L"warn-free\*(R" code is not a goal, and it is recommended not to build libev |
5054 | \&\*(L"warn-free\*(R" code is not a goal, and it is recommended not to build libev |
3771 | with any compiler warnings enabled unless you are prepared to cope with |
5055 | with any compiler warnings enabled unless you are prepared to cope with |
3772 | them (e.g. by ignoring them). Remember that warnings are just that: |
5056 | them (e.g. by ignoring them). Remember that warnings are just that: |
3773 | warnings, not errors, or proof of bugs. |
5057 | warnings, not errors, or proof of bugs. |
3774 | .Sh "\s-1VALGRIND\s0" |
5058 | .SS "\s-1VALGRIND\s0" |
3775 | .IX Subsection "VALGRIND" |
5059 | .IX Subsection "VALGRIND" |
3776 | Valgrind has a special section here because it is a popular tool that is |
5060 | Valgrind has a special section here because it is a popular tool that is |
3777 | highly useful. Unfortunately, valgrind reports are very hard to interpret. |
5061 | highly useful. Unfortunately, valgrind reports are very hard to interpret. |
3778 | .PP |
5062 | .PP |
3779 | If you think you found a bug (memory leak, uninitialised data access etc.) |
5063 | If you think you found a bug (memory leak, uninitialised data access etc.) |
… | |
… | |
3804 | .PP |
5088 | .PP |
3805 | If you need, for some reason, empty reports from valgrind for your project |
5089 | If you need, for some reason, empty reports from valgrind for your project |
3806 | I suggest using suppression lists. |
5090 | I suggest using suppression lists. |
3807 | .SH "PORTABILITY NOTES" |
5091 | .SH "PORTABILITY NOTES" |
3808 | .IX Header "PORTABILITY NOTES" |
5092 | .IX Header "PORTABILITY NOTES" |
|
|
5093 | .SS "\s-1GNU/LINUX\s0 32 \s-1BIT\s0 \s-1LIMITATIONS\s0" |
|
|
5094 | .IX Subsection "GNU/LINUX 32 BIT LIMITATIONS" |
|
|
5095 | GNU/Linux is the only common platform that supports 64 bit file/large file |
|
|
5096 | interfaces but \fIdisables\fR them by default. |
|
|
5097 | .PP |
|
|
5098 | That means that libev compiled in the default environment doesn't support |
|
|
5099 | files larger than 2GiB or so, which mainly affects \f(CW\*(C`ev_stat\*(C'\fR watchers. |
|
|
5100 | .PP |
|
|
5101 | Unfortunately, many programs try to work around this GNU/Linux issue |
|
|
5102 | by enabling the large file \s-1API\s0, which makes them incompatible with the |
|
|
5103 | standard libev compiled for their system. |
|
|
5104 | .PP |
|
|
5105 | Likewise, libev cannot enable the large file \s-1API\s0 itself as this would |
|
|
5106 | suddenly make it incompatible to the default compile time environment, |
|
|
5107 | i.e. all programs not using special compile switches. |
|
|
5108 | .SS "\s-1OS/X\s0 \s-1AND\s0 \s-1DARWIN\s0 \s-1BUGS\s0" |
|
|
5109 | .IX Subsection "OS/X AND DARWIN BUGS" |
|
|
5110 | The whole thing is a bug if you ask me \- basically any system interface |
|
|
5111 | you touch is broken, whether it is locales, poll, kqueue or even the |
|
|
5112 | OpenGL drivers. |
|
|
5113 | .PP |
|
|
5114 | \fI\f(CI\*(C`kqueue\*(C'\fI is buggy\fR |
|
|
5115 | .IX Subsection "kqueue is buggy" |
|
|
5116 | .PP |
|
|
5117 | The kqueue syscall is broken in all known versions \- most versions support |
|
|
5118 | only sockets, many support pipes. |
|
|
5119 | .PP |
|
|
5120 | Libev tries to work around this by not using \f(CW\*(C`kqueue\*(C'\fR by default on this |
|
|
5121 | rotten platform, but of course you can still ask for it when creating a |
|
|
5122 | loop \- embedding a socket-only kqueue loop into a select-based one is |
|
|
5123 | probably going to work well. |
|
|
5124 | .PP |
|
|
5125 | \fI\f(CI\*(C`poll\*(C'\fI is buggy\fR |
|
|
5126 | .IX Subsection "poll is buggy" |
|
|
5127 | .PP |
|
|
5128 | Instead of fixing \f(CW\*(C`kqueue\*(C'\fR, Apple replaced their (working) \f(CW\*(C`poll\*(C'\fR |
|
|
5129 | implementation by something calling \f(CW\*(C`kqueue\*(C'\fR internally around the 10.5.6 |
|
|
5130 | release, so now \f(CW\*(C`kqueue\*(C'\fR \fIand\fR \f(CW\*(C`poll\*(C'\fR are broken. |
|
|
5131 | .PP |
|
|
5132 | Libev tries to work around this by not using \f(CW\*(C`poll\*(C'\fR by default on |
|
|
5133 | this rotten platform, but of course you can still ask for it when creating |
|
|
5134 | a loop. |
|
|
5135 | .PP |
|
|
5136 | \fI\f(CI\*(C`select\*(C'\fI is buggy\fR |
|
|
5137 | .IX Subsection "select is buggy" |
|
|
5138 | .PP |
|
|
5139 | All that's left is \f(CW\*(C`select\*(C'\fR, and of course Apple found a way to fuck this |
|
|
5140 | one up as well: On \s-1OS/X\s0, \f(CW\*(C`select\*(C'\fR actively limits the number of file |
|
|
5141 | descriptors you can pass in to 1024 \- your program suddenly crashes when |
|
|
5142 | you use more. |
|
|
5143 | .PP |
|
|
5144 | There is an undocumented \*(L"workaround\*(R" for this \- defining |
|
|
5145 | \&\f(CW\*(C`_DARWIN_UNLIMITED_SELECT\*(C'\fR, which libev tries to use, so select \fIshould\fR |
|
|
5146 | work on \s-1OS/X\s0. |
|
|
5147 | .SS "\s-1SOLARIS\s0 \s-1PROBLEMS\s0 \s-1AND\s0 \s-1WORKAROUNDS\s0" |
|
|
5148 | .IX Subsection "SOLARIS PROBLEMS AND WORKAROUNDS" |
|
|
5149 | \fI\f(CI\*(C`errno\*(C'\fI reentrancy\fR |
|
|
5150 | .IX Subsection "errno reentrancy" |
|
|
5151 | .PP |
|
|
5152 | The default compile environment on Solaris is unfortunately so |
|
|
5153 | thread-unsafe that you can't even use components/libraries compiled |
|
|
5154 | without \f(CW\*(C`\-D_REENTRANT\*(C'\fR in a threaded program, which, of course, isn't |
|
|
5155 | defined by default. A valid, if stupid, implementation choice. |
|
|
5156 | .PP |
|
|
5157 | If you want to use libev in threaded environments you have to make sure |
|
|
5158 | it's compiled with \f(CW\*(C`_REENTRANT\*(C'\fR defined. |
|
|
5159 | .PP |
|
|
5160 | \fIEvent port backend\fR |
|
|
5161 | .IX Subsection "Event port backend" |
|
|
5162 | .PP |
|
|
5163 | The scalable event interface for Solaris is called \*(L"event |
|
|
5164 | ports\*(R". Unfortunately, this mechanism is very buggy in all major |
|
|
5165 | releases. If you run into high \s-1CPU\s0 usage, your program freezes or you get |
|
|
5166 | a large number of spurious wakeups, make sure you have all the relevant |
|
|
5167 | and latest kernel patches applied. No, I don't know which ones, but there |
|
|
5168 | are multiple ones to apply, and afterwards, event ports actually work |
|
|
5169 | great. |
|
|
5170 | .PP |
|
|
5171 | If you can't get it to work, you can try running the program by setting |
|
|
5172 | the environment variable \f(CW\*(C`LIBEV_FLAGS=3\*(C'\fR to only allow \f(CW\*(C`poll\*(C'\fR and |
|
|
5173 | \&\f(CW\*(C`select\*(C'\fR backends. |
|
|
5174 | .SS "\s-1AIX\s0 \s-1POLL\s0 \s-1BUG\s0" |
|
|
5175 | .IX Subsection "AIX POLL BUG" |
|
|
5176 | \&\s-1AIX\s0 unfortunately has a broken \f(CW\*(C`poll.h\*(C'\fR header. Libev works around |
|
|
5177 | this by trying to avoid the poll backend altogether (i.e. it's not even |
|
|
5178 | compiled in), which normally isn't a big problem as \f(CW\*(C`select\*(C'\fR works fine |
|
|
5179 | with large bitsets on \s-1AIX\s0, and \s-1AIX\s0 is dead anyway. |
3809 | .Sh "\s-1WIN32\s0 \s-1PLATFORM\s0 \s-1LIMITATIONS\s0 \s-1AND\s0 \s-1WORKAROUNDS\s0" |
5180 | .SS "\s-1WIN32\s0 \s-1PLATFORM\s0 \s-1LIMITATIONS\s0 \s-1AND\s0 \s-1WORKAROUNDS\s0" |
3810 | .IX Subsection "WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS" |
5181 | .IX Subsection "WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS" |
|
|
5182 | \fIGeneral issues\fR |
|
|
5183 | .IX Subsection "General issues" |
|
|
5184 | .PP |
3811 | Win32 doesn't support any of the standards (e.g. \s-1POSIX\s0) that libev |
5185 | Win32 doesn't support any of the standards (e.g. \s-1POSIX\s0) that libev |
3812 | requires, and its I/O model is fundamentally incompatible with the \s-1POSIX\s0 |
5186 | requires, and its I/O model is fundamentally incompatible with the \s-1POSIX\s0 |
3813 | model. Libev still offers limited functionality on this platform in |
5187 | model. Libev still offers limited functionality on this platform in |
3814 | the form of the \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR backend, and only supports socket |
5188 | the form of the \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR backend, and only supports socket |
3815 | descriptors. This only applies when using Win32 natively, not when using |
5189 | descriptors. This only applies when using Win32 natively, not when using |
3816 | e.g. cygwin. |
5190 | e.g. cygwin. Actually, it only applies to the microsofts own compilers, |
|
|
5191 | as every compiler comes with a slightly differently broken/incompatible |
|
|
5192 | environment. |
3817 | .PP |
5193 | .PP |
3818 | Lifting these limitations would basically require the full |
5194 | Lifting these limitations would basically require the full |
3819 | re-implementation of the I/O system. If you are into these kinds of |
5195 | re-implementation of the I/O system. If you are into this kind of thing, |
3820 | things, then note that glib does exactly that for you in a very portable |
5196 | then note that glib does exactly that for you in a very portable way (note |
3821 | way (note also that glib is the slowest event library known to man). |
5197 | also that glib is the slowest event library known to man). |
3822 | .PP |
5198 | .PP |
3823 | There is no supported compilation method available on windows except |
5199 | There is no supported compilation method available on windows except |
3824 | embedding it into other applications. |
5200 | embedding it into other applications. |
|
|
5201 | .PP |
|
|
5202 | Sensible signal handling is officially unsupported by Microsoft \- libev |
|
|
5203 | tries its best, but under most conditions, signals will simply not work. |
3825 | .PP |
5204 | .PP |
3826 | Not a libev limitation but worth mentioning: windows apparently doesn't |
5205 | Not a libev limitation but worth mentioning: windows apparently doesn't |
3827 | accept large writes: instead of resulting in a partial write, windows will |
5206 | accept large writes: instead of resulting in a partial write, windows will |
3828 | either accept everything or return \f(CW\*(C`ENOBUFS\*(C'\fR if the buffer is too large, |
5207 | either accept everything or return \f(CW\*(C`ENOBUFS\*(C'\fR if the buffer is too large, |
3829 | so make sure you only write small amounts into your sockets (less than a |
5208 | so make sure you only write small amounts into your sockets (less than a |
… | |
… | |
3834 | the abysmal performance of winsockets, using a large number of sockets |
5213 | the abysmal performance of winsockets, using a large number of sockets |
3835 | is not recommended (and not reasonable). If your program needs to use |
5214 | is not recommended (and not reasonable). If your program needs to use |
3836 | more than a hundred or so sockets, then likely it needs to use a totally |
5215 | more than a hundred or so sockets, then likely it needs to use a totally |
3837 | different implementation for windows, as libev offers the \s-1POSIX\s0 readiness |
5216 | different implementation for windows, as libev offers the \s-1POSIX\s0 readiness |
3838 | notification model, which cannot be implemented efficiently on windows |
5217 | notification model, which cannot be implemented efficiently on windows |
3839 | (Microsoft monopoly games). |
5218 | (due to Microsoft monopoly games). |
3840 | .PP |
5219 | .PP |
3841 | A typical way to use libev under windows is to embed it (see the embedding |
5220 | A typical way to use libev under windows is to embed it (see the embedding |
3842 | section for details) and use the following \fIevwrap.h\fR header file instead |
5221 | section for details) and use the following \fIevwrap.h\fR header file instead |
3843 | of \fIev.h\fR: |
5222 | of \fIev.h\fR: |
3844 | .PP |
5223 | .PP |
… | |
… | |
3854 | .PP |
5233 | .PP |
3855 | .Vb 2 |
5234 | .Vb 2 |
3856 | \& #include "evwrap.h" |
5235 | \& #include "evwrap.h" |
3857 | \& #include "ev.c" |
5236 | \& #include "ev.c" |
3858 | .Ve |
5237 | .Ve |
3859 | .IP "The winsocket select function" 4 |
5238 | .PP |
|
|
5239 | \fIThe winsocket \f(CI\*(C`select\*(C'\fI function\fR |
3860 | .IX Item "The winsocket select function" |
5240 | .IX Subsection "The winsocket select function" |
|
|
5241 | .PP |
3861 | The winsocket \f(CW\*(C`select\*(C'\fR function doesn't follow \s-1POSIX\s0 in that it |
5242 | The winsocket \f(CW\*(C`select\*(C'\fR function doesn't follow \s-1POSIX\s0 in that it |
3862 | requires socket \fIhandles\fR and not socket \fIfile descriptors\fR (it is |
5243 | requires socket \fIhandles\fR and not socket \fIfile descriptors\fR (it is |
3863 | also extremely buggy). This makes select very inefficient, and also |
5244 | also extremely buggy). This makes select very inefficient, and also |
3864 | requires a mapping from file descriptors to socket handles (the Microsoft |
5245 | requires a mapping from file descriptors to socket handles (the Microsoft |
3865 | C runtime provides the function \f(CW\*(C`_open_osfhandle\*(C'\fR for this). See the |
5246 | C runtime provides the function \f(CW\*(C`_open_osfhandle\*(C'\fR for this). See the |
3866 | discussion of the \f(CW\*(C`EV_SELECT_USE_FD_SET\*(C'\fR, \f(CW\*(C`EV_SELECT_IS_WINSOCKET\*(C'\fR and |
5247 | discussion of the \f(CW\*(C`EV_SELECT_USE_FD_SET\*(C'\fR, \f(CW\*(C`EV_SELECT_IS_WINSOCKET\*(C'\fR and |
3867 | \&\f(CW\*(C`EV_FD_TO_WIN32_HANDLE\*(C'\fR preprocessor symbols for more info. |
5248 | \&\f(CW\*(C`EV_FD_TO_WIN32_HANDLE\*(C'\fR preprocessor symbols for more info. |
3868 | .Sp |
5249 | .PP |
3869 | The configuration for a \*(L"naked\*(R" win32 using the Microsoft runtime |
5250 | The configuration for a \*(L"naked\*(R" win32 using the Microsoft runtime |
3870 | libraries and raw winsocket select is: |
5251 | libraries and raw winsocket select is: |
3871 | .Sp |
5252 | .PP |
3872 | .Vb 2 |
5253 | .Vb 2 |
3873 | \& #define EV_USE_SELECT 1 |
5254 | \& #define EV_USE_SELECT 1 |
3874 | \& #define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */ |
5255 | \& #define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */ |
3875 | .Ve |
5256 | .Ve |
3876 | .Sp |
5257 | .PP |
3877 | Note that winsockets handling of fd sets is O(n), so you can easily get a |
5258 | Note that winsockets handling of fd sets is O(n), so you can easily get a |
3878 | complexity in the O(nA\*^X) range when using win32. |
5259 | complexity in the O(nA\*^X) range when using win32. |
|
|
5260 | .PP |
3879 | .IP "Limited number of file descriptors" 4 |
5261 | \fILimited number of file descriptors\fR |
3880 | .IX Item "Limited number of file descriptors" |
5262 | .IX Subsection "Limited number of file descriptors" |
|
|
5263 | .PP |
3881 | Windows has numerous arbitrary (and low) limits on things. |
5264 | Windows has numerous arbitrary (and low) limits on things. |
3882 | .Sp |
5265 | .PP |
3883 | Early versions of winsocket's select only supported waiting for a maximum |
5266 | Early versions of winsocket's select only supported waiting for a maximum |
3884 | of \f(CW64\fR handles (probably owning to the fact that all windows kernels |
5267 | of \f(CW64\fR handles (probably owning to the fact that all windows kernels |
3885 | can only wait for \f(CW64\fR things at the same time internally; Microsoft |
5268 | can only wait for \f(CW64\fR things at the same time internally; Microsoft |
3886 | recommends spawning a chain of threads and wait for 63 handles and the |
5269 | recommends spawning a chain of threads and wait for 63 handles and the |
3887 | previous thread in each. Great). |
5270 | previous thread in each. Sounds great!). |
3888 | .Sp |
5271 | .PP |
3889 | Newer versions support more handles, but you need to define \f(CW\*(C`FD_SETSIZE\*(C'\fR |
5272 | Newer versions support more handles, but you need to define \f(CW\*(C`FD_SETSIZE\*(C'\fR |
3890 | to some high number (e.g. \f(CW2048\fR) before compiling the winsocket select |
5273 | to some high number (e.g. \f(CW2048\fR) before compiling the winsocket select |
3891 | call (which might be in libev or elsewhere, for example, perl does its own |
5274 | call (which might be in libev or elsewhere, for example, perl and many |
3892 | select emulation on windows). |
5275 | other interpreters do their own select emulation on windows). |
3893 | .Sp |
5276 | .PP |
3894 | Another limit is the number of file descriptors in the Microsoft runtime |
5277 | Another limit is the number of file descriptors in the Microsoft runtime |
3895 | libraries, which by default is \f(CW64\fR (there must be a hidden \fI64\fR fetish |
5278 | libraries, which by default is \f(CW64\fR (there must be a hidden \fI64\fR |
3896 | or something like this inside Microsoft). You can increase this by calling |
5279 | fetish or something like this inside Microsoft). You can increase this |
3897 | \&\f(CW\*(C`_setmaxstdio\*(C'\fR, which can increase this limit to \f(CW2048\fR (another |
5280 | by calling \f(CW\*(C`_setmaxstdio\*(C'\fR, which can increase this limit to \f(CW2048\fR |
3898 | arbitrary limit), but is broken in many versions of the Microsoft runtime |
5281 | (another arbitrary limit), but is broken in many versions of the Microsoft |
3899 | libraries. |
|
|
3900 | .Sp |
|
|
3901 | This might get you to about \f(CW512\fR or \f(CW2048\fR sockets (depending on |
5282 | runtime libraries. This might get you to about \f(CW512\fR or \f(CW2048\fR sockets |
3902 | windows version and/or the phase of the moon). To get more, you need to |
5283 | (depending on windows version and/or the phase of the moon). To get more, |
3903 | wrap all I/O functions and provide your own fd management, but the cost of |
5284 | you need to wrap all I/O functions and provide your own fd management, but |
3904 | calling select (O(nA\*^X)) will likely make this unworkable. |
5285 | the cost of calling select (O(nA\*^X)) will likely make this unworkable. |
3905 | .Sh "\s-1PORTABILITY\s0 \s-1REQUIREMENTS\s0" |
5286 | .SS "\s-1PORTABILITY\s0 \s-1REQUIREMENTS\s0" |
3906 | .IX Subsection "PORTABILITY REQUIREMENTS" |
5287 | .IX Subsection "PORTABILITY REQUIREMENTS" |
3907 | In addition to a working ISO-C implementation and of course the |
5288 | In addition to a working ISO-C implementation and of course the |
3908 | backend-specific APIs, libev relies on a few additional extensions: |
5289 | backend-specific APIs, libev relies on a few additional extensions: |
3909 | .ie n .IP """void (*)(ev_watcher_type *, int revents)""\fR must have compatible calling conventions regardless of \f(CW""ev_watcher_type *""." 4 |
5290 | .ie n .IP """void (*)(ev_watcher_type *, int revents)"" must have compatible calling conventions regardless of ""ev_watcher_type *""." 4 |
3910 | .el .IP "\f(CWvoid (*)(ev_watcher_type *, int revents)\fR must have compatible calling conventions regardless of \f(CWev_watcher_type *\fR." 4 |
5291 | .el .IP "\f(CWvoid (*)(ev_watcher_type *, int revents)\fR must have compatible calling conventions regardless of \f(CWev_watcher_type *\fR." 4 |
3911 | .IX Item "void (*)(ev_watcher_type *, int revents) must have compatible calling conventions regardless of ev_watcher_type *." |
5292 | .IX Item "void (*)(ev_watcher_type *, int revents) must have compatible calling conventions regardless of ev_watcher_type *." |
3912 | Libev assumes not only that all watcher pointers have the same internal |
5293 | Libev assumes not only that all watcher pointers have the same internal |
3913 | structure (guaranteed by \s-1POSIX\s0 but not by \s-1ISO\s0 C for example), but it also |
5294 | structure (guaranteed by \s-1POSIX\s0 but not by \s-1ISO\s0 C for example), but it also |
3914 | assumes that the same (machine) code can be used to call any watcher |
5295 | assumes that the same (machine) code can be used to call any watcher |
3915 | callback: The watcher callbacks have different type signatures, but libev |
5296 | callback: The watcher callbacks have different type signatures, but libev |
3916 | calls them using an \f(CW\*(C`ev_watcher *\*(C'\fR internally. |
5297 | calls them using an \f(CW\*(C`ev_watcher *\*(C'\fR internally. |
|
|
5298 | .IP "pointer accesses must be thread-atomic" 4 |
|
|
5299 | .IX Item "pointer accesses must be thread-atomic" |
|
|
5300 | Accessing a pointer value must be atomic, it must both be readable and |
|
|
5301 | writable in one piece \- this is the case on all current architectures. |
3917 | .ie n .IP """sig_atomic_t volatile"" must be thread-atomic as well" 4 |
5302 | .ie n .IP """sig_atomic_t volatile"" must be thread-atomic as well" 4 |
3918 | .el .IP "\f(CWsig_atomic_t volatile\fR must be thread-atomic as well" 4 |
5303 | .el .IP "\f(CWsig_atomic_t volatile\fR must be thread-atomic as well" 4 |
3919 | .IX Item "sig_atomic_t volatile must be thread-atomic as well" |
5304 | .IX Item "sig_atomic_t volatile must be thread-atomic as well" |
3920 | The type \f(CW\*(C`sig_atomic_t volatile\*(C'\fR (or whatever is defined as |
5305 | The type \f(CW\*(C`sig_atomic_t volatile\*(C'\fR (or whatever is defined as |
3921 | \&\f(CW\*(C`EV_ATOMIC_T\*(C'\fR) must be atomic with respect to accesses from different |
5306 | \&\f(CW\*(C`EV_ATOMIC_T\*(C'\fR) must be atomic with respect to accesses from different |
… | |
… | |
3944 | watchers. |
5329 | watchers. |
3945 | .ie n .IP """double"" must hold a time value in seconds with enough accuracy" 4 |
5330 | .ie n .IP """double"" must hold a time value in seconds with enough accuracy" 4 |
3946 | .el .IP "\f(CWdouble\fR must hold a time value in seconds with enough accuracy" 4 |
5331 | .el .IP "\f(CWdouble\fR must hold a time value in seconds with enough accuracy" 4 |
3947 | .IX Item "double must hold a time value in seconds with enough accuracy" |
5332 | .IX Item "double must hold a time value in seconds with enough accuracy" |
3948 | The type \f(CW\*(C`double\*(C'\fR is used to represent timestamps. It is required to |
5333 | The type \f(CW\*(C`double\*(C'\fR is used to represent timestamps. It is required to |
3949 | have at least 51 bits of mantissa (and 9 bits of exponent), which is good |
5334 | have at least 51 bits of mantissa (and 9 bits of exponent), which is |
3950 | enough for at least into the year 4000. This requirement is fulfilled by |
5335 | good enough for at least into the year 4000 with millisecond accuracy |
|
|
5336 | (the design goal for libev). This requirement is overfulfilled by |
3951 | implementations implementing \s-1IEEE\s0 754 (basically all existing ones). |
5337 | implementations using \s-1IEEE\s0 754, which is basically all existing ones. |
|
|
5338 | .Sp |
|
|
5339 | With \s-1IEEE\s0 754 doubles, you get microsecond accuracy until at least the |
|
|
5340 | year 2255 (and millisecond accuracy till the year 287396 \- by then, libev |
|
|
5341 | is either obsolete or somebody patched it to use \f(CW\*(C`long double\*(C'\fR or |
|
|
5342 | something like that, just kidding). |
3952 | .PP |
5343 | .PP |
3953 | If you know of other additional requirements drop me a note. |
5344 | If you know of other additional requirements drop me a note. |
3954 | .SH "ALGORITHMIC COMPLEXITIES" |
5345 | .SH "ALGORITHMIC COMPLEXITIES" |
3955 | .IX Header "ALGORITHMIC COMPLEXITIES" |
5346 | .IX Header "ALGORITHMIC COMPLEXITIES" |
3956 | In this section the complexities of (many of) the algorithms used inside |
5347 | In this section the complexities of (many of) the algorithms used inside |
… | |
… | |
4010 | .IX Item "Processing ev_async_send: O(number_of_async_watchers)" |
5401 | .IX Item "Processing ev_async_send: O(number_of_async_watchers)" |
4011 | .IP "Processing signals: O(max_signal_number)" 4 |
5402 | .IP "Processing signals: O(max_signal_number)" 4 |
4012 | .IX Item "Processing signals: O(max_signal_number)" |
5403 | .IX Item "Processing signals: O(max_signal_number)" |
4013 | .PD |
5404 | .PD |
4014 | Sending involves a system call \fIiff\fR there were no other \f(CW\*(C`ev_async_send\*(C'\fR |
5405 | Sending involves a system call \fIiff\fR there were no other \f(CW\*(C`ev_async_send\*(C'\fR |
4015 | calls in the current loop iteration. Checking for async and signal events |
5406 | calls in the current loop iteration and the loop is currently |
|
|
5407 | blocked. Checking for async and signal events involves iterating over all |
4016 | involves iterating over all running async watchers or all signal numbers. |
5408 | running async watchers or all signal numbers. |
|
|
5409 | .SH "PORTING FROM LIBEV 3.X TO 4.X" |
|
|
5410 | .IX Header "PORTING FROM LIBEV 3.X TO 4.X" |
|
|
5411 | The major version 4 introduced some incompatible changes to the \s-1API\s0. |
|
|
5412 | .PP |
|
|
5413 | At the moment, the \f(CW\*(C`ev.h\*(C'\fR header file provides compatibility definitions |
|
|
5414 | for all changes, so most programs should still compile. The compatibility |
|
|
5415 | layer might be removed in later versions of libev, so better update to the |
|
|
5416 | new \s-1API\s0 early than late. |
|
|
5417 | .ie n .IP """EV_COMPAT3"" backwards compatibility mechanism" 4 |
|
|
5418 | .el .IP "\f(CWEV_COMPAT3\fR backwards compatibility mechanism" 4 |
|
|
5419 | .IX Item "EV_COMPAT3 backwards compatibility mechanism" |
|
|
5420 | The backward compatibility mechanism can be controlled by |
|
|
5421 | \&\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 |
|
|
5422 | section. |
|
|
5423 | .ie n .IP """ev_default_destroy"" and ""ev_default_fork"" have been removed" 4 |
|
|
5424 | .el .IP "\f(CWev_default_destroy\fR and \f(CWev_default_fork\fR have been removed" 4 |
|
|
5425 | .IX Item "ev_default_destroy and ev_default_fork have been removed" |
|
|
5426 | These calls can be replaced easily by their \f(CW\*(C`ev_loop_xxx\*(C'\fR counterparts: |
|
|
5427 | .Sp |
|
|
5428 | .Vb 2 |
|
|
5429 | \& ev_loop_destroy (EV_DEFAULT_UC); |
|
|
5430 | \& ev_loop_fork (EV_DEFAULT); |
|
|
5431 | .Ve |
|
|
5432 | .IP "function/symbol renames" 4 |
|
|
5433 | .IX Item "function/symbol renames" |
|
|
5434 | A number of functions and symbols have been renamed: |
|
|
5435 | .Sp |
|
|
5436 | .Vb 3 |
|
|
5437 | \& ev_loop => ev_run |
|
|
5438 | \& EVLOOP_NONBLOCK => EVRUN_NOWAIT |
|
|
5439 | \& EVLOOP_ONESHOT => EVRUN_ONCE |
|
|
5440 | \& |
|
|
5441 | \& ev_unloop => ev_break |
|
|
5442 | \& EVUNLOOP_CANCEL => EVBREAK_CANCEL |
|
|
5443 | \& EVUNLOOP_ONE => EVBREAK_ONE |
|
|
5444 | \& EVUNLOOP_ALL => EVBREAK_ALL |
|
|
5445 | \& |
|
|
5446 | \& EV_TIMEOUT => EV_TIMER |
|
|
5447 | \& |
|
|
5448 | \& ev_loop_count => ev_iteration |
|
|
5449 | \& ev_loop_depth => ev_depth |
|
|
5450 | \& ev_loop_verify => ev_verify |
|
|
5451 | .Ve |
|
|
5452 | .Sp |
|
|
5453 | Most functions working on \f(CW\*(C`struct ev_loop\*(C'\fR objects don't have an |
|
|
5454 | \&\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 |
|
|
5455 | associated constants have been renamed to not collide with the \f(CW\*(C`struct |
|
|
5456 | ev_loop\*(C'\fR anymore and \f(CW\*(C`EV_TIMER\*(C'\fR now follows the same naming scheme |
|
|
5457 | as all other watcher types. Note that \f(CW\*(C`ev_loop_fork\*(C'\fR is still called |
|
|
5458 | \&\f(CW\*(C`ev_loop_fork\*(C'\fR because it would otherwise clash with the \f(CW\*(C`ev_fork\*(C'\fR |
|
|
5459 | typedef. |
|
|
5460 | .ie n .IP """EV_MINIMAL"" mechanism replaced by ""EV_FEATURES""" 4 |
|
|
5461 | .el .IP "\f(CWEV_MINIMAL\fR mechanism replaced by \f(CWEV_FEATURES\fR" 4 |
|
|
5462 | .IX Item "EV_MINIMAL mechanism replaced by EV_FEATURES" |
|
|
5463 | The preprocessor symbol \f(CW\*(C`EV_MINIMAL\*(C'\fR has been replaced by a different |
|
|
5464 | mechanism, \f(CW\*(C`EV_FEATURES\*(C'\fR. Programs using \f(CW\*(C`EV_MINIMAL\*(C'\fR usually compile |
|
|
5465 | and work, but the library code will of course be larger. |
|
|
5466 | .SH "GLOSSARY" |
|
|
5467 | .IX Header "GLOSSARY" |
|
|
5468 | .IP "active" 4 |
|
|
5469 | .IX Item "active" |
|
|
5470 | A watcher is active as long as it has been started and not yet stopped. |
|
|
5471 | See \*(L"\s-1WATCHER\s0 \s-1STATES\s0\*(R" for details. |
|
|
5472 | .IP "application" 4 |
|
|
5473 | .IX Item "application" |
|
|
5474 | In this document, an application is whatever is using libev. |
|
|
5475 | .IP "backend" 4 |
|
|
5476 | .IX Item "backend" |
|
|
5477 | The part of the code dealing with the operating system interfaces. |
|
|
5478 | .IP "callback" 4 |
|
|
5479 | .IX Item "callback" |
|
|
5480 | The address of a function that is called when some event has been |
|
|
5481 | detected. Callbacks are being passed the event loop, the watcher that |
|
|
5482 | received the event, and the actual event bitset. |
|
|
5483 | .IP "callback/watcher invocation" 4 |
|
|
5484 | .IX Item "callback/watcher invocation" |
|
|
5485 | The act of calling the callback associated with a watcher. |
|
|
5486 | .IP "event" 4 |
|
|
5487 | .IX Item "event" |
|
|
5488 | A change of state of some external event, such as data now being available |
|
|
5489 | for reading on a file descriptor, time having passed or simply not having |
|
|
5490 | any other events happening anymore. |
|
|
5491 | .Sp |
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5492 | In libev, events are represented as single bits (such as \f(CW\*(C`EV_READ\*(C'\fR or |
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5493 | \&\f(CW\*(C`EV_TIMER\*(C'\fR). |
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5494 | .IP "event library" 4 |
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5495 | .IX Item "event library" |
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5496 | A software package implementing an event model and loop. |
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5497 | .IP "event loop" 4 |
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5498 | .IX Item "event loop" |
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5499 | An entity that handles and processes external events and converts them |
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5500 | into callback invocations. |
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5501 | .IP "event model" 4 |
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5502 | .IX Item "event model" |
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5503 | The model used to describe how an event loop handles and processes |
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5504 | watchers and events. |
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5505 | .IP "pending" 4 |
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5506 | .IX Item "pending" |
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5507 | A watcher is pending as soon as the corresponding event has been |
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5508 | detected. See \*(L"\s-1WATCHER\s0 \s-1STATES\s0\*(R" for details. |
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5509 | .IP "real time" 4 |
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5510 | .IX Item "real time" |
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5511 | The physical time that is observed. It is apparently strictly monotonic :) |
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5512 | .IP "wall-clock time" 4 |
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5513 | .IX Item "wall-clock time" |
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5514 | The time and date as shown on clocks. Unlike real time, it can actually |
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5515 | be wrong and jump forwards and backwards, e.g. when you adjust your |
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5516 | clock. |
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5517 | .IP "watcher" 4 |
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5518 | .IX Item "watcher" |
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5519 | A data structure that describes interest in certain events. Watchers need |
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5520 | to be started (attached to an event loop) before they can receive events. |
4017 | .SH "AUTHOR" |
5521 | .SH "AUTHOR" |
4018 | .IX Header "AUTHOR" |
5522 | .IX Header "AUTHOR" |
4019 | Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael Magnusson. |
5523 | Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael |
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5524 | Magnusson and Emanuele Giaquinta, and minor corrections by many others. |