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124 | .\" ======================================================================== |
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134 | .\" |
126 | .IX Title "LIBEV 3" |
135 | .IX Title "LIBEV 3" |
127 | .TH LIBEV 3 "2010-10-25" "libev-4.00" "libev - high performance full featured event loop" |
136 | .TH LIBEV 3 "2023-05-15" "libev-4.33" "libev - high performance full featured event loop" |
128 | .\" For nroff, turn off justification. Always turn off hyphenation; it makes |
137 | .\" For nroff, turn off justification. Always turn off hyphenation; it makes |
129 | .\" way too many mistakes in technical documents. |
138 | .\" way too many mistakes in technical documents. |
130 | .if n .ad l |
139 | .if n .ad l |
131 | .nh |
140 | .nh |
132 | .SH "NAME" |
141 | .SH "NAME" |
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134 | .SH "SYNOPSIS" |
143 | .SH "SYNOPSIS" |
135 | .IX Header "SYNOPSIS" |
144 | .IX Header "SYNOPSIS" |
136 | .Vb 1 |
145 | .Vb 1 |
137 | \& #include <ev.h> |
146 | \& #include <ev.h> |
138 | .Ve |
147 | .Ve |
139 | .SS "\s-1EXAMPLE\s0 \s-1PROGRAM\s0" |
148 | .SS "\s-1EXAMPLE PROGRAM\s0" |
140 | .IX Subsection "EXAMPLE PROGRAM" |
149 | .IX Subsection "EXAMPLE PROGRAM" |
141 | .Vb 2 |
150 | .Vb 2 |
142 | \& // a single header file is required |
151 | \& // a single header file is required |
143 | \& #include <ev.h> |
152 | \& #include <ev.h> |
144 | \& |
153 | \& |
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189 | \& ev_timer_start (loop, &timeout_watcher); |
198 | \& ev_timer_start (loop, &timeout_watcher); |
190 | \& |
199 | \& |
191 | \& // now wait for events to arrive |
200 | \& // now wait for events to arrive |
192 | \& ev_run (loop, 0); |
201 | \& ev_run (loop, 0); |
193 | \& |
202 | \& |
194 | \& // unloop was called, so exit |
203 | \& // break was called, so exit |
195 | \& return 0; |
204 | \& return 0; |
196 | \& } |
205 | \& } |
197 | .Ve |
206 | .Ve |
198 | .SH "ABOUT THIS DOCUMENT" |
207 | .SH "ABOUT THIS DOCUMENT" |
199 | .IX Header "ABOUT THIS DOCUMENT" |
208 | .IX Header "ABOUT THIS DOCUMENT" |
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212 | throughout this document. |
221 | throughout this document. |
213 | .SH "WHAT TO READ WHEN IN A HURRY" |
222 | .SH "WHAT TO READ WHEN IN A HURRY" |
214 | .IX Header "WHAT TO READ WHEN IN A HURRY" |
223 | .IX Header "WHAT TO READ WHEN IN A HURRY" |
215 | This manual tries to be very detailed, but unfortunately, this also makes |
224 | This manual tries to be very detailed, but unfortunately, this also makes |
216 | it very long. If you just want to know the basics of libev, I suggest |
225 | it very long. If you just want to know the basics of libev, I suggest |
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 |
226 | reading \*(L"\s-1ANATOMY OF A WATCHER\*(R"\s0, then the \*(L"\s-1EXAMPLE PROGRAM\*(R"\s0 above and |
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 |
227 | look up the missing functions in \*(L"\s-1GLOBAL FUNCTIONS\*(R"\s0 and the \f(CW\*(C`ev_io\*(C'\fR and |
219 | \&\f(CW\*(C`ev_timer\*(C'\fR sections in \*(L"\s-1WATCHER\s0 \s-1TYPES\s0\*(R". |
228 | \&\f(CW\*(C`ev_timer\*(C'\fR sections in \*(L"\s-1WATCHER TYPES\*(R"\s0. |
220 | .SH "ABOUT LIBEV" |
229 | .SH "ABOUT LIBEV" |
221 | .IX Header "ABOUT LIBEV" |
230 | .IX Header "ABOUT LIBEV" |
222 | Libev is an event loop: you register interest in certain events (such as a |
231 | Libev is an event loop: you register interest in certain events (such as a |
223 | file descriptor being readable or a timeout occurring), and it will manage |
232 | file descriptor being readable or a timeout occurring), and it will manage |
224 | these event sources and provide your program with events. |
233 | these event sources and provide your program with events. |
… | |
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231 | watchers\fR, which are relatively small C structures you initialise with the |
240 | watchers\fR, which are relatively small C structures you initialise with the |
232 | details of the event, and then hand it over to libev by \fIstarting\fR the |
241 | details of the event, and then hand it over to libev by \fIstarting\fR the |
233 | watcher. |
242 | watcher. |
234 | .SS "\s-1FEATURES\s0" |
243 | .SS "\s-1FEATURES\s0" |
235 | .IX Subsection "FEATURES" |
244 | .IX Subsection "FEATURES" |
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 |
245 | Libev supports \f(CW\*(C`select\*(C'\fR, \f(CW\*(C`poll\*(C'\fR, the Linux-specific aio and \f(CW\*(C`epoll\*(C'\fR |
237 | BSD-specific \f(CW\*(C`kqueue\*(C'\fR and the Solaris-specific event port mechanisms |
246 | interfaces, the BSD-specific \f(CW\*(C`kqueue\*(C'\fR and the Solaris-specific event port |
238 | for file descriptor events (\f(CW\*(C`ev_io\*(C'\fR), the Linux \f(CW\*(C`inotify\*(C'\fR interface |
247 | mechanisms for file descriptor events (\f(CW\*(C`ev_io\*(C'\fR), the Linux \f(CW\*(C`inotify\*(C'\fR |
239 | (for \f(CW\*(C`ev_stat\*(C'\fR), Linux eventfd/signalfd (for faster and cleaner |
248 | interface (for \f(CW\*(C`ev_stat\*(C'\fR), Linux eventfd/signalfd (for faster and cleaner |
240 | inter-thread wakeup (\f(CW\*(C`ev_async\*(C'\fR)/signal handling (\f(CW\*(C`ev_signal\*(C'\fR)) relative |
249 | inter-thread wakeup (\f(CW\*(C`ev_async\*(C'\fR)/signal handling (\f(CW\*(C`ev_signal\*(C'\fR)) relative |
241 | timers (\f(CW\*(C`ev_timer\*(C'\fR), absolute timers with customised rescheduling |
250 | timers (\f(CW\*(C`ev_timer\*(C'\fR), absolute timers with customised rescheduling |
242 | (\f(CW\*(C`ev_periodic\*(C'\fR), synchronous signals (\f(CW\*(C`ev_signal\*(C'\fR), process status |
251 | (\f(CW\*(C`ev_periodic\*(C'\fR), synchronous signals (\f(CW\*(C`ev_signal\*(C'\fR), process status |
243 | change events (\f(CW\*(C`ev_child\*(C'\fR), and event watchers dealing with the event |
252 | change events (\f(CW\*(C`ev_child\*(C'\fR), and event watchers dealing with the event |
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 |
253 | loop mechanism itself (\f(CW\*(C`ev_idle\*(C'\fR, \f(CW\*(C`ev_embed\*(C'\fR, \f(CW\*(C`ev_prepare\*(C'\fR and |
245 | \&\f(CW\*(C`ev_check\*(C'\fR watchers) as well as file watchers (\f(CW\*(C`ev_stat\*(C'\fR) and even |
254 | \&\f(CW\*(C`ev_check\*(C'\fR watchers) as well as file watchers (\f(CW\*(C`ev_stat\*(C'\fR) and even |
246 | limited support for fork events (\f(CW\*(C`ev_fork\*(C'\fR). |
255 | limited support for fork events (\f(CW\*(C`ev_fork\*(C'\fR). |
247 | .PP |
256 | .PP |
248 | It also is quite fast (see this |
257 | It also is quite fast (see this |
249 | <benchmark> comparing it to libevent |
258 | benchmark <http://libev.schmorp.de/bench.html> comparing it to libevent |
250 | for example). |
259 | for example). |
251 | .SS "\s-1CONVENTIONS\s0" |
260 | .SS "\s-1CONVENTIONS\s0" |
252 | .IX Subsection "CONVENTIONS" |
261 | .IX Subsection "CONVENTIONS" |
253 | Libev is very configurable. In this manual the default (and most common) |
262 | Libev is very configurable. In this manual the default (and most common) |
254 | configuration will be described, which supports multiple event loops. For |
263 | configuration will be described, which supports multiple event loops. For |
255 | more info about various configuration options please have a look at |
264 | more info about various configuration options please have a look at |
256 | \&\fB\s-1EMBED\s0\fR section in this manual. If libev was configured without support |
265 | \&\fB\s-1EMBED\s0\fR section in this manual. If libev was configured without support |
257 | for multiple event loops, then all functions taking an initial argument of |
266 | for multiple event loops, then all functions taking an initial argument of |
258 | name \f(CW\*(C`loop\*(C'\fR (which is always of type \f(CW\*(C`struct ev_loop *\*(C'\fR) will not have |
267 | name \f(CW\*(C`loop\*(C'\fR (which is always of type \f(CW\*(C`struct ev_loop *\*(C'\fR) will not have |
259 | this argument. |
268 | this argument. |
260 | .SS "\s-1TIME\s0 \s-1REPRESENTATION\s0" |
269 | .SS "\s-1TIME REPRESENTATION\s0" |
261 | .IX Subsection "TIME REPRESENTATION" |
270 | .IX Subsection "TIME REPRESENTATION" |
262 | Libev represents time as a single floating point number, representing |
271 | Libev represents time as a single floating point number, representing |
263 | the (fractional) number of seconds since the (\s-1POSIX\s0) epoch (in practice |
272 | the (fractional) number of seconds since the (\s-1POSIX\s0) epoch (in practice |
264 | somewhere near the beginning of 1970, details are complicated, don't |
273 | somewhere near the beginning of 1970, details are complicated, don't |
265 | ask). This type is called \f(CW\*(C`ev_tstamp\*(C'\fR, which is what you should use |
274 | ask). This type is called \f(CW\*(C`ev_tstamp\*(C'\fR, which is what you should use |
… | |
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282 | When libev detects a usage error such as a negative timer interval, then |
291 | When libev detects a usage error such as a negative timer interval, then |
283 | it will print a diagnostic message and abort (via the \f(CW\*(C`assert\*(C'\fR mechanism, |
292 | it will print a diagnostic message and abort (via the \f(CW\*(C`assert\*(C'\fR mechanism, |
284 | so \f(CW\*(C`NDEBUG\*(C'\fR will disable this checking): these are programming errors in |
293 | so \f(CW\*(C`NDEBUG\*(C'\fR will disable this checking): these are programming errors in |
285 | the libev caller and need to be fixed there. |
294 | the libev caller and need to be fixed there. |
286 | .PP |
295 | .PP |
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296 | Via the \f(CW\*(C`EV_FREQUENT\*(C'\fR macro you can compile in and/or enable extensive |
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297 | consistency checking code inside libev that can be used to check for |
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298 | internal inconsistencies, suually caused by application bugs. |
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299 | .PP |
287 | Libev also has a few internal error-checking \f(CW\*(C`assert\*(C'\fRions, and also has |
300 | Libev also has a few internal error-checking \f(CW\*(C`assert\*(C'\fRions. These do not |
288 | extensive consistency checking code. These do not trigger under normal |
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289 | circumstances, as they indicate either a bug in libev or worse. |
301 | trigger under normal circumstances, as they indicate either a bug in libev |
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302 | or worse. |
290 | .SH "GLOBAL FUNCTIONS" |
303 | .SH "GLOBAL FUNCTIONS" |
291 | .IX Header "GLOBAL FUNCTIONS" |
304 | .IX Header "GLOBAL FUNCTIONS" |
292 | These functions can be called anytime, even before initialising the |
305 | These functions can be called anytime, even before initialising the |
293 | library in any way. |
306 | library in any way. |
294 | .IP "ev_tstamp ev_time ()" 4 |
307 | .IP "ev_tstamp ev_time ()" 4 |
295 | .IX Item "ev_tstamp ev_time ()" |
308 | .IX Item "ev_tstamp ev_time ()" |
296 | Returns the current time as libev would use it. Please note that the |
309 | Returns the current time as libev would use it. Please note that the |
297 | \&\f(CW\*(C`ev_now\*(C'\fR function is usually faster and also often returns the timestamp |
310 | \&\f(CW\*(C`ev_now\*(C'\fR function is usually faster and also often returns the timestamp |
298 | you actually want to know. Also interesting is the combination of |
311 | you actually want to know. Also interesting is the combination of |
299 | \&\f(CW\*(C`ev_update_now\*(C'\fR and \f(CW\*(C`ev_now\*(C'\fR. |
312 | \&\f(CW\*(C`ev_now_update\*(C'\fR and \f(CW\*(C`ev_now\*(C'\fR. |
300 | .IP "ev_sleep (ev_tstamp interval)" 4 |
313 | .IP "ev_sleep (ev_tstamp interval)" 4 |
301 | .IX Item "ev_sleep (ev_tstamp interval)" |
314 | .IX Item "ev_sleep (ev_tstamp interval)" |
302 | Sleep for the given interval: The current thread will be blocked until |
315 | Sleep for the given interval: The current thread will be blocked |
303 | either it is interrupted or the given time interval has passed. Basically |
316 | until either it is interrupted or the given time interval has |
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317 | passed (approximately \- it might return a bit earlier even if not |
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318 | interrupted). Returns immediately if \f(CW\*(C`interval <= 0\*(C'\fR. |
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319 | .Sp |
304 | this is a sub-second-resolution \f(CW\*(C`sleep ()\*(C'\fR. |
320 | Basically this is a sub-second-resolution \f(CW\*(C`sleep ()\*(C'\fR. |
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321 | .Sp |
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322 | The range of the \f(CW\*(C`interval\*(C'\fR is limited \- libev only guarantees to work |
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323 | with sleep times of up to one day (\f(CW\*(C`interval <= 86400\*(C'\fR). |
305 | .IP "int ev_version_major ()" 4 |
324 | .IP "int ev_version_major ()" 4 |
306 | .IX Item "int ev_version_major ()" |
325 | .IX Item "int ev_version_major ()" |
307 | .PD 0 |
326 | .PD 0 |
308 | .IP "int ev_version_minor ()" 4 |
327 | .IP "int ev_version_minor ()" 4 |
309 | .IX Item "int ev_version_minor ()" |
328 | .IX Item "int ev_version_minor ()" |
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361 | current system. To find which embeddable backends might be supported on |
380 | current system. To find which embeddable backends might be supported on |
362 | the current system, you would need to look at \f(CW\*(C`ev_embeddable_backends () |
381 | the current system, you would need to look at \f(CW\*(C`ev_embeddable_backends () |
363 | & ev_supported_backends ()\*(C'\fR, likewise for recommended ones. |
382 | & ev_supported_backends ()\*(C'\fR, likewise for recommended ones. |
364 | .Sp |
383 | .Sp |
365 | See the description of \f(CW\*(C`ev_embed\*(C'\fR watchers for more info. |
384 | See the description of \f(CW\*(C`ev_embed\*(C'\fR watchers for more info. |
366 | .IP "ev_set_allocator (void *(*cb)(void *ptr, long size)) [\s-1NOT\s0 \s-1REENTRANT\s0]" 4 |
385 | .IP "ev_set_allocator (void *(*cb)(void *ptr, long size) throw ())" 4 |
367 | .IX Item "ev_set_allocator (void *(*cb)(void *ptr, long size)) [NOT REENTRANT]" |
386 | .IX Item "ev_set_allocator (void *(*cb)(void *ptr, long size) throw ())" |
368 | Sets the allocation function to use (the prototype is similar \- the |
387 | Sets the allocation function to use (the prototype is similar \- the |
369 | semantics are identical to the \f(CW\*(C`realloc\*(C'\fR C89/SuS/POSIX function). It is |
388 | semantics are identical to the \f(CW\*(C`realloc\*(C'\fR C89/SuS/POSIX function). It is |
370 | used to allocate and free memory (no surprises here). If it returns zero |
389 | used to allocate and free memory (no surprises here). If it returns zero |
371 | when memory needs to be allocated (\f(CW\*(C`size != 0\*(C'\fR), the library might abort |
390 | when memory needs to be allocated (\f(CW\*(C`size != 0\*(C'\fR), the library might abort |
372 | or take some potentially destructive action. |
391 | or take some potentially destructive action. |
… | |
… | |
377 | .Sp |
396 | .Sp |
378 | You could override this function in high-availability programs to, say, |
397 | You could override this function in high-availability programs to, say, |
379 | free some memory if it cannot allocate memory, to use a special allocator, |
398 | free some memory if it cannot allocate memory, to use a special allocator, |
380 | or even to sleep a while and retry until some memory is available. |
399 | or even to sleep a while and retry until some memory is available. |
381 | .Sp |
400 | .Sp |
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401 | Example: The following is the \f(CW\*(C`realloc\*(C'\fR function that libev itself uses |
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402 | which should work with \f(CW\*(C`realloc\*(C'\fR and \f(CW\*(C`free\*(C'\fR functions of all kinds and |
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403 | is probably a good basis for your own implementation. |
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404 | .Sp |
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405 | .Vb 5 |
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406 | \& static void * |
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407 | \& ev_realloc_emul (void *ptr, long size) EV_NOEXCEPT |
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408 | \& { |
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409 | \& if (size) |
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410 | \& return realloc (ptr, size); |
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411 | \& |
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412 | \& free (ptr); |
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413 | \& return 0; |
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414 | \& } |
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415 | .Ve |
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416 | .Sp |
382 | Example: Replace the libev allocator with one that waits a bit and then |
417 | Example: Replace the libev allocator with one that waits a bit and then |
383 | retries (example requires a standards-compliant \f(CW\*(C`realloc\*(C'\fR). |
418 | retries. |
384 | .Sp |
419 | .Sp |
385 | .Vb 6 |
420 | .Vb 8 |
386 | \& static void * |
421 | \& static void * |
387 | \& persistent_realloc (void *ptr, size_t size) |
422 | \& persistent_realloc (void *ptr, size_t size) |
388 | \& { |
423 | \& { |
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424 | \& if (!size) |
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425 | \& { |
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426 | \& free (ptr); |
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427 | \& return 0; |
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428 | \& } |
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429 | \& |
389 | \& for (;;) |
430 | \& for (;;) |
390 | \& { |
431 | \& { |
391 | \& void *newptr = realloc (ptr, size); |
432 | \& void *newptr = realloc (ptr, size); |
392 | \& |
433 | \& |
393 | \& if (newptr) |
434 | \& if (newptr) |
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398 | \& } |
439 | \& } |
399 | \& |
440 | \& |
400 | \& ... |
441 | \& ... |
401 | \& ev_set_allocator (persistent_realloc); |
442 | \& ev_set_allocator (persistent_realloc); |
402 | .Ve |
443 | .Ve |
403 | .IP "ev_set_syserr_cb (void (*cb)(const char *msg)); [\s-1NOT\s0 \s-1REENTRANT\s0]" 4 |
444 | .IP "ev_set_syserr_cb (void (*cb)(const char *msg) throw ())" 4 |
404 | .IX Item "ev_set_syserr_cb (void (*cb)(const char *msg)); [NOT REENTRANT]" |
445 | .IX Item "ev_set_syserr_cb (void (*cb)(const char *msg) throw ())" |
405 | Set the callback function to call on a retryable system call error (such |
446 | Set the callback function to call on a retryable system call error (such |
406 | as failed select, poll, epoll_wait). The message is a printable string |
447 | as failed select, poll, epoll_wait). The message is a printable string |
407 | indicating the system call or subsystem causing the problem. If this |
448 | indicating the system call or subsystem causing the problem. If this |
408 | callback is set, then libev will expect it to remedy the situation, no |
449 | callback is set, then libev will expect it to remedy the situation, no |
409 | matter what, when it returns. That is, libev will generally retry the |
450 | matter what, when it returns. That is, libev will generally retry the |
… | |
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421 | \& } |
462 | \& } |
422 | \& |
463 | \& |
423 | \& ... |
464 | \& ... |
424 | \& ev_set_syserr_cb (fatal_error); |
465 | \& ev_set_syserr_cb (fatal_error); |
425 | .Ve |
466 | .Ve |
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467 | .IP "ev_feed_signal (int signum)" 4 |
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468 | .IX Item "ev_feed_signal (int signum)" |
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469 | This function can be used to \*(L"simulate\*(R" a signal receive. It is completely |
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470 | safe to call this function at any time, from any context, including signal |
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471 | handlers or random threads. |
|
|
472 | .Sp |
|
|
473 | Its main use is to customise signal handling in your process, especially |
|
|
474 | in the presence of threads. For example, you could block signals |
|
|
475 | by default in all threads (and specifying \f(CW\*(C`EVFLAG_NOSIGMASK\*(C'\fR when |
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|
476 | creating any loops), and in one thread, use \f(CW\*(C`sigwait\*(C'\fR or any other |
|
|
477 | mechanism to wait for signals, then \*(L"deliver\*(R" them to libev by calling |
|
|
478 | \&\f(CW\*(C`ev_feed_signal\*(C'\fR. |
426 | .SH "FUNCTIONS CONTROLLING EVENT LOOPS" |
479 | .SH "FUNCTIONS CONTROLLING EVENT LOOPS" |
427 | .IX Header "FUNCTIONS CONTROLLING EVENT LOOPS" |
480 | .IX Header "FUNCTIONS CONTROLLING EVENT LOOPS" |
428 | An event loop is described by a \f(CW\*(C`struct ev_loop *\*(C'\fR (the \f(CW\*(C`struct\*(C'\fR is |
481 | An event loop is described by a \f(CW\*(C`struct ev_loop *\*(C'\fR (the \f(CW\*(C`struct\*(C'\fR is |
429 | \&\fInot\fR optional in this case unless libev 3 compatibility is disabled, as |
482 | \&\fInot\fR optional in this case unless libev 3 compatibility is disabled, as |
430 | libev 3 had an \f(CW\*(C`ev_loop\*(C'\fR function colliding with the struct name). |
483 | libev 3 had an \f(CW\*(C`ev_loop\*(C'\fR function colliding with the struct name). |
… | |
… | |
475 | .IP "struct ev_loop *ev_loop_new (unsigned int flags)" 4 |
528 | .IP "struct ev_loop *ev_loop_new (unsigned int flags)" 4 |
476 | .IX Item "struct ev_loop *ev_loop_new (unsigned int flags)" |
529 | .IX Item "struct ev_loop *ev_loop_new (unsigned int flags)" |
477 | This will create and initialise a new event loop object. If the loop |
530 | This will create and initialise a new event loop object. If the loop |
478 | could not be initialised, returns false. |
531 | could not be initialised, returns false. |
479 | .Sp |
532 | .Sp |
480 | Note that this function \fIis\fR thread-safe, and one common way to use |
533 | This function is thread-safe, and one common way to use libev with |
481 | libev with threads is indeed to create one loop per thread, and using the |
534 | threads is indeed to create one loop per thread, and using the default |
482 | default loop in the \*(L"main\*(R" or \*(L"initial\*(R" thread. |
535 | loop in the \*(L"main\*(R" or \*(L"initial\*(R" thread. |
483 | .Sp |
536 | .Sp |
484 | The flags argument can be used to specify special behaviour or specific |
537 | The flags argument can be used to specify special behaviour or specific |
485 | backends to use, and is usually specified as \f(CW0\fR (or \f(CW\*(C`EVFLAG_AUTO\*(C'\fR). |
538 | backends to use, and is usually specified as \f(CW0\fR (or \f(CW\*(C`EVFLAG_AUTO\*(C'\fR). |
486 | .Sp |
539 | .Sp |
487 | The following flags are supported: |
540 | The following flags are supported: |
… | |
… | |
496 | .IX Item "EVFLAG_NOENV" |
549 | .IX Item "EVFLAG_NOENV" |
497 | If this flag bit is or'ed into the flag value (or the program runs setuid |
550 | If this flag bit is or'ed into the flag value (or the program runs setuid |
498 | or setgid) then libev will \fInot\fR look at the environment variable |
551 | or setgid) then libev will \fInot\fR look at the environment variable |
499 | \&\f(CW\*(C`LIBEV_FLAGS\*(C'\fR. Otherwise (the default), this environment variable will |
552 | \&\f(CW\*(C`LIBEV_FLAGS\*(C'\fR. Otherwise (the default), this environment variable will |
500 | override the flags completely if it is found in the environment. This is |
553 | override the flags completely if it is found in the environment. This is |
501 | useful to try out specific backends to test their performance, or to work |
554 | useful to try out specific backends to test their performance, to work |
502 | around bugs. |
555 | around bugs, or to make libev threadsafe (accessing environment variables |
|
|
556 | cannot be done in a threadsafe way, but usually it works if no other |
|
|
557 | thread modifies them). |
503 | .ie n .IP """EVFLAG_FORKCHECK""" 4 |
558 | .ie n .IP """EVFLAG_FORKCHECK""" 4 |
504 | .el .IP "\f(CWEVFLAG_FORKCHECK\fR" 4 |
559 | .el .IP "\f(CWEVFLAG_FORKCHECK\fR" 4 |
505 | .IX Item "EVFLAG_FORKCHECK" |
560 | .IX Item "EVFLAG_FORKCHECK" |
506 | Instead of calling \f(CW\*(C`ev_loop_fork\*(C'\fR manually after a fork, you can also |
561 | Instead of calling \f(CW\*(C`ev_loop_fork\*(C'\fR manually after a fork, you can also |
507 | make libev check for a fork in each iteration by enabling this flag. |
562 | make libev check for a fork in each iteration by enabling this flag. |
508 | .Sp |
563 | .Sp |
509 | This works by calling \f(CW\*(C`getpid ()\*(C'\fR on every iteration of the loop, |
564 | This works by calling \f(CW\*(C`getpid ()\*(C'\fR on every iteration of the loop, |
510 | and thus this might slow down your event loop if you do a lot of loop |
565 | and thus this might slow down your event loop if you do a lot of loop |
511 | iterations and little real work, but is usually not noticeable (on my |
566 | iterations and little real work, but is usually not noticeable (on my |
512 | GNU/Linux system for example, \f(CW\*(C`getpid\*(C'\fR is actually a simple 5\-insn sequence |
567 | GNU/Linux system for example, \f(CW\*(C`getpid\*(C'\fR is actually a simple 5\-insn |
513 | without a system call and thus \fIvery\fR fast, but my GNU/Linux system also has |
568 | sequence without a system call and thus \fIvery\fR fast, but my GNU/Linux |
514 | \&\f(CW\*(C`pthread_atfork\*(C'\fR which is even faster). |
569 | system also has \f(CW\*(C`pthread_atfork\*(C'\fR which is even faster). (Update: glibc |
|
|
570 | versions 2.25 apparently removed the \f(CW\*(C`getpid\*(C'\fR optimisation again). |
515 | .Sp |
571 | .Sp |
516 | The big advantage of this flag is that you can forget about fork (and |
572 | The big advantage of this flag is that you can forget about fork (and |
517 | forget about forgetting to tell libev about forking) when you use this |
573 | forget about forgetting to tell libev about forking, although you still |
518 | flag. |
574 | have to ignore \f(CW\*(C`SIGPIPE\*(C'\fR) when you use this flag. |
519 | .Sp |
575 | .Sp |
520 | This flag setting cannot be overridden or specified in the \f(CW\*(C`LIBEV_FLAGS\*(C'\fR |
576 | This flag setting cannot be overridden or specified in the \f(CW\*(C`LIBEV_FLAGS\*(C'\fR |
521 | environment variable. |
577 | environment variable. |
522 | .ie n .IP """EVFLAG_NOINOTIFY""" 4 |
578 | .ie n .IP """EVFLAG_NOINOTIFY""" 4 |
523 | .el .IP "\f(CWEVFLAG_NOINOTIFY\fR" 4 |
579 | .el .IP "\f(CWEVFLAG_NOINOTIFY\fR" 4 |
524 | .IX Item "EVFLAG_NOINOTIFY" |
580 | .IX Item "EVFLAG_NOINOTIFY" |
525 | When this flag is specified, then libev will not attempt to use the |
581 | When this flag is specified, then libev will not attempt to use the |
526 | \&\fIinotify\fR \s-1API\s0 for it's \f(CW\*(C`ev_stat\*(C'\fR watchers. Apart from debugging and |
582 | \&\fIinotify\fR \s-1API\s0 for its \f(CW\*(C`ev_stat\*(C'\fR watchers. Apart from debugging and |
527 | testing, this flag can be useful to conserve inotify file descriptors, as |
583 | testing, this flag can be useful to conserve inotify file descriptors, as |
528 | otherwise each loop using \f(CW\*(C`ev_stat\*(C'\fR watchers consumes one inotify handle. |
584 | otherwise each loop using \f(CW\*(C`ev_stat\*(C'\fR watchers consumes one inotify handle. |
529 | .ie n .IP """EVFLAG_SIGNALFD""" 4 |
585 | .ie n .IP """EVFLAG_SIGNALFD""" 4 |
530 | .el .IP "\f(CWEVFLAG_SIGNALFD\fR" 4 |
586 | .el .IP "\f(CWEVFLAG_SIGNALFD\fR" 4 |
531 | .IX Item "EVFLAG_SIGNALFD" |
587 | .IX Item "EVFLAG_SIGNALFD" |
532 | When this flag is specified, then libev will attempt to use the |
588 | When this flag is specified, then libev will attempt to use the |
533 | \&\fIsignalfd\fR \s-1API\s0 for it's \f(CW\*(C`ev_signal\*(C'\fR (and \f(CW\*(C`ev_child\*(C'\fR) watchers. This \s-1API\s0 |
589 | \&\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 |
534 | delivers signals synchronously, which makes it both faster and might make |
590 | delivers signals synchronously, which makes it both faster and might make |
535 | it possible to get the queued signal data. It can also simplify signal |
591 | it possible to get the queued signal data. It can also simplify signal |
536 | handling with threads, as long as you properly block signals in your |
592 | handling with threads, as long as you properly block signals in your |
537 | threads that are not interested in handling them. |
593 | threads that are not interested in handling them. |
538 | .Sp |
594 | .Sp |
539 | Signalfd will not be used by default as this changes your signal mask, and |
595 | Signalfd will not be used by default as this changes your signal mask, and |
540 | there are a lot of shoddy libraries and programs (glib's threadpool for |
596 | there are a lot of shoddy libraries and programs (glib's threadpool for |
541 | example) that can't properly initialise their signal masks. |
597 | example) that can't properly initialise their signal masks. |
|
|
598 | .ie n .IP """EVFLAG_NOSIGMASK""" 4 |
|
|
599 | .el .IP "\f(CWEVFLAG_NOSIGMASK\fR" 4 |
|
|
600 | .IX Item "EVFLAG_NOSIGMASK" |
|
|
601 | When this flag is specified, then libev will avoid to modify the signal |
|
|
602 | mask. Specifically, this means you have to make sure signals are unblocked |
|
|
603 | when you want to receive them. |
|
|
604 | .Sp |
|
|
605 | This behaviour is useful when you want to do your own signal handling, or |
|
|
606 | want to handle signals only in specific threads and want to avoid libev |
|
|
607 | unblocking the signals. |
|
|
608 | .Sp |
|
|
609 | It's also required by \s-1POSIX\s0 in a threaded program, as libev calls |
|
|
610 | \&\f(CW\*(C`sigprocmask\*(C'\fR, whose behaviour is officially unspecified. |
|
|
611 | .ie n .IP """EVFLAG_NOTIMERFD""" 4 |
|
|
612 | .el .IP "\f(CWEVFLAG_NOTIMERFD\fR" 4 |
|
|
613 | .IX Item "EVFLAG_NOTIMERFD" |
|
|
614 | When this flag is specified, the libev will avoid using a \f(CW\*(C`timerfd\*(C'\fR to |
|
|
615 | detect time jumps. It will still be able to detect time jumps, but takes |
|
|
616 | longer and has a lower accuracy in doing so, but saves a file descriptor |
|
|
617 | per loop. |
|
|
618 | .Sp |
|
|
619 | The current implementation only tries to use a \f(CW\*(C`timerfd\*(C'\fR when the first |
|
|
620 | \&\f(CW\*(C`ev_periodic\*(C'\fR watcher is started and falls back on other methods if it |
|
|
621 | cannot be created, but this behaviour might change in the future. |
542 | .ie n .IP """EVBACKEND_SELECT"" (value 1, portable select backend)" 4 |
622 | .ie n .IP """EVBACKEND_SELECT"" (value 1, portable select backend)" 4 |
543 | .el .IP "\f(CWEVBACKEND_SELECT\fR (value 1, portable select backend)" 4 |
623 | .el .IP "\f(CWEVBACKEND_SELECT\fR (value 1, portable select backend)" 4 |
544 | .IX Item "EVBACKEND_SELECT (value 1, portable select backend)" |
624 | .IX Item "EVBACKEND_SELECT (value 1, portable select backend)" |
545 | This is your standard \fIselect\fR\|(2) backend. Not \fIcompletely\fR standard, as |
625 | This is your standard \fBselect\fR\|(2) backend. Not \fIcompletely\fR standard, as |
546 | libev tries to roll its own fd_set with no limits on the number of fds, |
626 | libev tries to roll its own fd_set with no limits on the number of fds, |
547 | but if that fails, expect a fairly low limit on the number of fds when |
627 | but if that fails, expect a fairly low limit on the number of fds when |
548 | using this backend. It doesn't scale too well (O(highest_fd)), but its |
628 | using this backend. It doesn't scale too well (O(highest_fd)), but its |
549 | usually the fastest backend for a low number of (low-numbered :) fds. |
629 | usually the fastest backend for a low number of (low-numbered :) fds. |
550 | .Sp |
630 | .Sp |
… | |
… | |
558 | This backend maps \f(CW\*(C`EV_READ\*(C'\fR to the \f(CW\*(C`readfds\*(C'\fR set and \f(CW\*(C`EV_WRITE\*(C'\fR to the |
638 | This backend maps \f(CW\*(C`EV_READ\*(C'\fR to the \f(CW\*(C`readfds\*(C'\fR set and \f(CW\*(C`EV_WRITE\*(C'\fR to the |
559 | \&\f(CW\*(C`writefds\*(C'\fR set (and to work around Microsoft Windows bugs, also onto the |
639 | \&\f(CW\*(C`writefds\*(C'\fR set (and to work around Microsoft Windows bugs, also onto the |
560 | \&\f(CW\*(C`exceptfds\*(C'\fR set on that platform). |
640 | \&\f(CW\*(C`exceptfds\*(C'\fR set on that platform). |
561 | .ie n .IP """EVBACKEND_POLL"" (value 2, poll backend, available everywhere except on windows)" 4 |
641 | .ie n .IP """EVBACKEND_POLL"" (value 2, poll backend, available everywhere except on windows)" 4 |
562 | .el .IP "\f(CWEVBACKEND_POLL\fR (value 2, poll backend, available everywhere except on windows)" 4 |
642 | .el .IP "\f(CWEVBACKEND_POLL\fR (value 2, poll backend, available everywhere except on windows)" 4 |
563 | .IX Item "EVBACKEND_POLL (value 2, poll backend, available everywhere except on windows)" |
643 | .IX Item "EVBACKEND_POLL (value 2, poll backend, available everywhere except on windows)" |
564 | And this is your standard \fIpoll\fR\|(2) backend. It's more complicated |
644 | And this is your standard \fBpoll\fR\|(2) backend. It's more complicated |
565 | than select, but handles sparse fds better and has no artificial |
645 | than select, but handles sparse fds better and has no artificial |
566 | limit on the number of fds you can use (except it will slow down |
646 | limit on the number of fds you can use (except it will slow down |
567 | considerably with a lot of inactive fds). It scales similarly to select, |
647 | considerably with a lot of inactive fds). It scales similarly to select, |
568 | i.e. O(total_fds). See the entry for \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR, above, for |
648 | i.e. O(total_fds). See the entry for \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR, above, for |
569 | performance tips. |
649 | performance tips. |
570 | .Sp |
650 | .Sp |
571 | This backend maps \f(CW\*(C`EV_READ\*(C'\fR to \f(CW\*(C`POLLIN | POLLERR | POLLHUP\*(C'\fR, and |
651 | This backend maps \f(CW\*(C`EV_READ\*(C'\fR to \f(CW\*(C`POLLIN | POLLERR | POLLHUP\*(C'\fR, and |
572 | \&\f(CW\*(C`EV_WRITE\*(C'\fR to \f(CW\*(C`POLLOUT | POLLERR | POLLHUP\*(C'\fR. |
652 | \&\f(CW\*(C`EV_WRITE\*(C'\fR to \f(CW\*(C`POLLOUT | POLLERR | POLLHUP\*(C'\fR. |
573 | .ie n .IP """EVBACKEND_EPOLL"" (value 4, Linux)" 4 |
653 | .ie n .IP """EVBACKEND_EPOLL"" (value 4, Linux)" 4 |
574 | .el .IP "\f(CWEVBACKEND_EPOLL\fR (value 4, Linux)" 4 |
654 | .el .IP "\f(CWEVBACKEND_EPOLL\fR (value 4, Linux)" 4 |
575 | .IX Item "EVBACKEND_EPOLL (value 4, Linux)" |
655 | .IX Item "EVBACKEND_EPOLL (value 4, Linux)" |
576 | Use the linux-specific \fIepoll\fR\|(7) interface (for both pre\- and post\-2.6.9 |
656 | Use the Linux-specific \fBepoll\fR\|(7) interface (for both pre\- and post\-2.6.9 |
577 | kernels). |
657 | kernels). |
578 | .Sp |
658 | .Sp |
579 | For few fds, this backend is a bit little slower than poll and select, |
659 | For few fds, this backend is a bit little slower than poll and select, but |
580 | but it scales phenomenally better. While poll and select usually scale |
660 | it scales phenomenally better. While poll and select usually scale like |
581 | like O(total_fds) where n is the total number of fds (or the highest fd), |
661 | O(total_fds) where total_fds is the total number of fds (or the highest |
582 | epoll scales either O(1) or O(active_fds). |
662 | fd), epoll scales either O(1) or O(active_fds). |
583 | .Sp |
663 | .Sp |
584 | The epoll mechanism deserves honorable mention as the most misdesigned |
664 | The epoll mechanism deserves honorable mention as the most misdesigned |
585 | of the more advanced event mechanisms: mere annoyances include silently |
665 | of the more advanced event mechanisms: mere annoyances include silently |
586 | dropping file descriptors, requiring a system call per change per file |
666 | dropping file descriptors, requiring a system call per change per file |
587 | descriptor (and unnecessary guessing of parameters), problems with dup and |
667 | descriptor (and unnecessary guessing of parameters), problems with dup, |
|
|
668 | returning before the timeout value, resulting in additional iterations |
|
|
669 | (and only giving 5ms accuracy while select on the same platform gives |
588 | so on. The biggest issue is fork races, however \- if a program forks then |
670 | 0.1ms) and so on. The biggest issue is fork races, however \- if a program |
589 | \&\fIboth\fR parent and child process have to recreate the epoll set, which can |
671 | forks then \fIboth\fR parent and child process have to recreate the epoll |
590 | take considerable time (one syscall per file descriptor) and is of course |
672 | set, which can take considerable time (one syscall per file descriptor) |
591 | hard to detect. |
673 | and is of course hard to detect. |
592 | .Sp |
674 | .Sp |
593 | Epoll is also notoriously buggy \- embedding epoll fds \fIshould\fR work, but |
675 | Epoll is also notoriously buggy \- embedding epoll fds \fIshould\fR work, |
594 | of course \fIdoesn't\fR, and epoll just loves to report events for totally |
676 | but of course \fIdoesn't\fR, and epoll just loves to report events for |
595 | \&\fIdifferent\fR file descriptors (even already closed ones, so one cannot |
677 | totally \fIdifferent\fR file descriptors (even already closed ones, so |
596 | even remove them from the set) than registered in the set (especially |
678 | one cannot even remove them from the set) than registered in the set |
597 | on \s-1SMP\s0 systems). Libev tries to counter these spurious notifications by |
679 | (especially on \s-1SMP\s0 systems). Libev tries to counter these spurious |
598 | employing an additional generation counter and comparing that against the |
680 | notifications by employing an additional generation counter and comparing |
599 | events to filter out spurious ones, recreating the set when required. Last |
681 | that against the events to filter out spurious ones, recreating the set |
|
|
682 | when required. Epoll also erroneously rounds down timeouts, but gives you |
|
|
683 | no way to know when and by how much, so sometimes you have to busy-wait |
|
|
684 | because epoll returns immediately despite a nonzero timeout. And last |
600 | not least, it also refuses to work with some file descriptors which work |
685 | not least, it also refuses to work with some file descriptors which work |
601 | perfectly fine with \f(CW\*(C`select\*(C'\fR (files, many character devices...). |
686 | perfectly fine with \f(CW\*(C`select\*(C'\fR (files, many character devices...). |
|
|
687 | .Sp |
|
|
688 | Epoll is truly the train wreck among event poll mechanisms, a frankenpoll, |
|
|
689 | cobbled together in a hurry, no thought to design or interaction with |
|
|
690 | others. Oh, the pain, will it ever stop... |
602 | .Sp |
691 | .Sp |
603 | While stopping, setting and starting an I/O watcher in the same iteration |
692 | While stopping, setting and starting an I/O watcher in the same iteration |
604 | will result in some caching, there is still a system call per such |
693 | will result in some caching, there is still a system call per such |
605 | incident (because the same \fIfile descriptor\fR could point to a different |
694 | incident (because the same \fIfile descriptor\fR could point to a different |
606 | \&\fIfile description\fR now), so its best to avoid that. Also, \f(CW\*(C`dup ()\*(C'\fR'ed |
695 | \&\fIfile description\fR now), so its best to avoid that. Also, \f(CW\*(C`dup ()\*(C'\fR'ed |
… | |
… | |
618 | All this means that, in practice, \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR can be as fast or |
707 | All this means that, in practice, \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR can be as fast or |
619 | faster than epoll for maybe up to a hundred file descriptors, depending on |
708 | faster than epoll for maybe up to a hundred file descriptors, depending on |
620 | the usage. So sad. |
709 | the usage. So sad. |
621 | .Sp |
710 | .Sp |
622 | While nominally embeddable in other event loops, this feature is broken in |
711 | While nominally embeddable in other event loops, this feature is broken in |
623 | all kernel versions tested so far. |
712 | a lot of kernel revisions, but probably(!) works in current versions. |
|
|
713 | .Sp |
|
|
714 | This backend maps \f(CW\*(C`EV_READ\*(C'\fR and \f(CW\*(C`EV_WRITE\*(C'\fR in the same way as |
|
|
715 | \&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
|
|
716 | .ie n .IP """EVBACKEND_LINUXAIO"" (value 64, Linux)" 4 |
|
|
717 | .el .IP "\f(CWEVBACKEND_LINUXAIO\fR (value 64, Linux)" 4 |
|
|
718 | .IX Item "EVBACKEND_LINUXAIO (value 64, Linux)" |
|
|
719 | Use the Linux-specific Linux \s-1AIO\s0 (\fInot\fR \f(CWaio(7)\fR but \f(CWio_submit(2)\fR) event interface available in post\-4.18 kernels (but libev |
|
|
720 | only tries to use it in 4.19+). |
|
|
721 | .Sp |
|
|
722 | This is another Linux train wreck of an event interface. |
|
|
723 | .Sp |
|
|
724 | If this backend works for you (as of this writing, it was very |
|
|
725 | experimental), it is the best event interface available on Linux and might |
|
|
726 | be well worth enabling it \- if it isn't available in your kernel this will |
|
|
727 | be detected and this backend will be skipped. |
|
|
728 | .Sp |
|
|
729 | This backend can batch oneshot requests and supports a user-space ring |
|
|
730 | buffer to receive events. It also doesn't suffer from most of the design |
|
|
731 | problems of epoll (such as not being able to remove event sources from |
|
|
732 | the epoll set), and generally sounds too good to be true. Because, this |
|
|
733 | being the Linux kernel, of course it suffers from a whole new set of |
|
|
734 | limitations, forcing you to fall back to epoll, inheriting all its design |
|
|
735 | issues. |
|
|
736 | .Sp |
|
|
737 | For one, it is not easily embeddable (but probably could be done using |
|
|
738 | an event fd at some extra overhead). It also is subject to a system wide |
|
|
739 | limit that can be configured in \fI/proc/sys/fs/aio\-max\-nr\fR. If no \s-1AIO\s0 |
|
|
740 | requests are left, this backend will be skipped during initialisation, and |
|
|
741 | will switch to epoll when the loop is active. |
|
|
742 | .Sp |
|
|
743 | Most problematic in practice, however, is that not all file descriptors |
|
|
744 | work with it. For example, in Linux 5.1, \s-1TCP\s0 sockets, pipes, event fds, |
|
|
745 | files, \fI/dev/null\fR and many others are supported, but ttys do not work |
|
|
746 | properly (a known bug that the kernel developers don't care about, see |
|
|
747 | <https://lore.kernel.org/patchwork/patch/1047453/>), so this is not |
|
|
748 | (yet?) a generic event polling interface. |
|
|
749 | .Sp |
|
|
750 | Overall, it seems the Linux developers just don't want it to have a |
|
|
751 | generic event handling mechanism other than \f(CW\*(C`select\*(C'\fR or \f(CW\*(C`poll\*(C'\fR. |
|
|
752 | .Sp |
|
|
753 | To work around all these problem, the current version of libev uses its |
|
|
754 | epoll backend as a fallback for file descriptor types that do not work. Or |
|
|
755 | falls back completely to epoll if the kernel acts up. |
624 | .Sp |
756 | .Sp |
625 | This backend maps \f(CW\*(C`EV_READ\*(C'\fR and \f(CW\*(C`EV_WRITE\*(C'\fR in the same way as |
757 | This backend maps \f(CW\*(C`EV_READ\*(C'\fR and \f(CW\*(C`EV_WRITE\*(C'\fR in the same way as |
626 | \&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
758 | \&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
627 | .ie n .IP """EVBACKEND_KQUEUE"" (value 8, most \s-1BSD\s0 clones)" 4 |
759 | .ie n .IP """EVBACKEND_KQUEUE"" (value 8, most \s-1BSD\s0 clones)" 4 |
628 | .el .IP "\f(CWEVBACKEND_KQUEUE\fR (value 8, most \s-1BSD\s0 clones)" 4 |
760 | .el .IP "\f(CWEVBACKEND_KQUEUE\fR (value 8, most \s-1BSD\s0 clones)" 4 |
629 | .IX Item "EVBACKEND_KQUEUE (value 8, most BSD clones)" |
761 | .IX Item "EVBACKEND_KQUEUE (value 8, most BSD clones)" |
630 | Kqueue deserves special mention, as at the time of this writing, it |
762 | Kqueue deserves special mention, as at the time this backend was |
631 | was broken on all BSDs except NetBSD (usually it doesn't work reliably |
763 | implemented, it was broken on all BSDs except NetBSD (usually it doesn't |
632 | with anything but sockets and pipes, except on Darwin, where of course |
764 | work reliably with anything but sockets and pipes, except on Darwin, |
633 | it's completely useless). Unlike epoll, however, whose brokenness |
765 | where of course it's completely useless). Unlike epoll, however, whose |
634 | is by design, these kqueue bugs can (and eventually will) be fixed |
766 | brokenness is by design, these kqueue bugs can be (and mostly have been) |
635 | without \s-1API\s0 changes to existing programs. For this reason it's not being |
767 | fixed without \s-1API\s0 changes to existing programs. For this reason it's not |
636 | \&\*(L"auto-detected\*(R" unless you explicitly specify it in the flags (i.e. using |
768 | being \*(L"auto-detected\*(R" on all platforms unless you explicitly specify it |
637 | \&\f(CW\*(C`EVBACKEND_KQUEUE\*(C'\fR) or libev was compiled on a known-to-be-good (\-enough) |
769 | in the flags (i.e. using \f(CW\*(C`EVBACKEND_KQUEUE\*(C'\fR) or libev was compiled on a |
638 | system like NetBSD. |
770 | known-to-be-good (\-enough) system like NetBSD. |
639 | .Sp |
771 | .Sp |
640 | You still can embed kqueue into a normal poll or select backend and use it |
772 | You still can embed kqueue into a normal poll or select backend and use it |
641 | only for sockets (after having made sure that sockets work with kqueue on |
773 | only for sockets (after having made sure that sockets work with kqueue on |
642 | the target platform). See \f(CW\*(C`ev_embed\*(C'\fR watchers for more info. |
774 | the target platform). See \f(CW\*(C`ev_embed\*(C'\fR watchers for more info. |
643 | .Sp |
775 | .Sp |
644 | It scales in the same way as the epoll backend, but the interface to the |
776 | It scales in the same way as the epoll backend, but the interface to the |
645 | kernel is more efficient (which says nothing about its actual speed, of |
777 | kernel is more efficient (which says nothing about its actual speed, of |
646 | course). While stopping, setting and starting an I/O watcher does never |
778 | course). While stopping, setting and starting an I/O watcher does never |
647 | cause an extra system call as with \f(CW\*(C`EVBACKEND_EPOLL\*(C'\fR, it still adds up to |
779 | cause an extra system call as with \f(CW\*(C`EVBACKEND_EPOLL\*(C'\fR, it still adds up to |
648 | two event changes per incident. Support for \f(CW\*(C`fork ()\*(C'\fR is very bad (but |
780 | two event changes per incident. Support for \f(CW\*(C`fork ()\*(C'\fR is very bad (you |
649 | sane, unlike epoll) and it drops fds silently in similarly hard-to-detect |
781 | might have to leak fds on fork, but it's more sane than epoll) and it |
650 | cases |
782 | drops fds silently in similarly hard-to-detect cases. |
651 | .Sp |
783 | .Sp |
652 | This backend usually performs well under most conditions. |
784 | This backend usually performs well under most conditions. |
653 | .Sp |
785 | .Sp |
654 | While nominally embeddable in other event loops, this doesn't work |
786 | While nominally embeddable in other event loops, this doesn't work |
655 | everywhere, so you might need to test for this. And since it is broken |
787 | everywhere, so you might need to test for this. And since it is broken |
656 | almost everywhere, you should only use it when you have a lot of sockets |
788 | almost everywhere, you should only use it when you have a lot of sockets |
657 | (for which it usually works), by embedding it into another event loop |
789 | (for which it usually works), by embedding it into another event loop |
658 | (e.g. \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or \f(CW\*(C`EVBACKEND_POLL\*(C'\fR (but \f(CW\*(C`poll\*(C'\fR is of course |
790 | (e.g. \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or \f(CW\*(C`EVBACKEND_POLL\*(C'\fR (but \f(CW\*(C`poll\*(C'\fR is of course |
659 | also broken on \s-1OS\s0 X)) and, did I mention it, using it only for sockets. |
791 | also broken on \s-1OS X\s0)) and, did I mention it, using it only for sockets. |
660 | .Sp |
792 | .Sp |
661 | This backend maps \f(CW\*(C`EV_READ\*(C'\fR into an \f(CW\*(C`EVFILT_READ\*(C'\fR kevent with |
793 | This backend maps \f(CW\*(C`EV_READ\*(C'\fR into an \f(CW\*(C`EVFILT_READ\*(C'\fR kevent with |
662 | \&\f(CW\*(C`NOTE_EOF\*(C'\fR, and \f(CW\*(C`EV_WRITE\*(C'\fR into an \f(CW\*(C`EVFILT_WRITE\*(C'\fR kevent with |
794 | \&\f(CW\*(C`NOTE_EOF\*(C'\fR, and \f(CW\*(C`EV_WRITE\*(C'\fR into an \f(CW\*(C`EVFILT_WRITE\*(C'\fR kevent with |
663 | \&\f(CW\*(C`NOTE_EOF\*(C'\fR. |
795 | \&\f(CW\*(C`NOTE_EOF\*(C'\fR. |
664 | .ie n .IP """EVBACKEND_DEVPOLL"" (value 16, Solaris 8)" 4 |
796 | .ie n .IP """EVBACKEND_DEVPOLL"" (value 16, Solaris 8)" 4 |
… | |
… | |
668 | implementation). According to reports, \f(CW\*(C`/dev/poll\*(C'\fR only supports sockets |
800 | implementation). According to reports, \f(CW\*(C`/dev/poll\*(C'\fR only supports sockets |
669 | and is not embeddable, which would limit the usefulness of this backend |
801 | and is not embeddable, which would limit the usefulness of this backend |
670 | immensely. |
802 | immensely. |
671 | .ie n .IP """EVBACKEND_PORT"" (value 32, Solaris 10)" 4 |
803 | .ie n .IP """EVBACKEND_PORT"" (value 32, Solaris 10)" 4 |
672 | .el .IP "\f(CWEVBACKEND_PORT\fR (value 32, Solaris 10)" 4 |
804 | .el .IP "\f(CWEVBACKEND_PORT\fR (value 32, Solaris 10)" 4 |
673 | .IX Item "EVBACKEND_PORT (value 32, Solaris 10)" |
805 | .IX Item "EVBACKEND_PORT (value 32, Solaris 10)" |
674 | This uses the Solaris 10 event port mechanism. As with everything on Solaris, |
806 | This uses the Solaris 10 event port mechanism. As with everything on |
675 | it's really slow, but it still scales very well (O(active_fds)). |
807 | Solaris, it's really slow, but it still scales very well (O(active_fds)). |
676 | .Sp |
|
|
677 | Please note that Solaris event ports can deliver a lot of spurious |
|
|
678 | notifications, so you need to use non-blocking I/O or other means to avoid |
|
|
679 | blocking when no data (or space) is available. |
|
|
680 | .Sp |
808 | .Sp |
681 | While this backend scales well, it requires one system call per active |
809 | While this backend scales well, it requires one system call per active |
682 | file descriptor per loop iteration. For small and medium numbers of file |
810 | file descriptor per loop iteration. For small and medium numbers of file |
683 | descriptors a \*(L"slow\*(R" \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or \f(CW\*(C`EVBACKEND_POLL\*(C'\fR backend |
811 | descriptors a \*(L"slow\*(R" \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or \f(CW\*(C`EVBACKEND_POLL\*(C'\fR backend |
684 | might perform better. |
812 | might perform better. |
685 | .Sp |
813 | .Sp |
686 | On the positive side, with the exception of the spurious readiness |
814 | On the positive side, this backend actually performed fully to |
687 | notifications, this backend actually performed fully to specification |
|
|
688 | in all tests and is fully embeddable, which is a rare feat among the |
815 | specification in all tests and is fully embeddable, which is a rare feat |
689 | OS-specific backends (I vastly prefer correctness over speed hacks). |
816 | among the OS-specific backends (I vastly prefer correctness over speed |
|
|
817 | hacks). |
|
|
818 | .Sp |
|
|
819 | On the negative side, the interface is \fIbizarre\fR \- so bizarre that |
|
|
820 | even sun itself gets it wrong in their code examples: The event polling |
|
|
821 | function sometimes returns events to the caller even though an error |
|
|
822 | occurred, but with no indication whether it has done so or not (yes, it's |
|
|
823 | even documented that way) \- deadly for edge-triggered interfaces where you |
|
|
824 | absolutely have to know whether an event occurred or not because you have |
|
|
825 | to re-arm the watcher. |
|
|
826 | .Sp |
|
|
827 | Fortunately libev seems to be able to work around these idiocies. |
690 | .Sp |
828 | .Sp |
691 | This backend maps \f(CW\*(C`EV_READ\*(C'\fR and \f(CW\*(C`EV_WRITE\*(C'\fR in the same way as |
829 | This backend maps \f(CW\*(C`EV_READ\*(C'\fR and \f(CW\*(C`EV_WRITE\*(C'\fR in the same way as |
692 | \&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
830 | \&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
693 | .ie n .IP """EVBACKEND_ALL""" 4 |
831 | .ie n .IP """EVBACKEND_ALL""" 4 |
694 | .el .IP "\f(CWEVBACKEND_ALL\fR" 4 |
832 | .el .IP "\f(CWEVBACKEND_ALL\fR" 4 |
695 | .IX Item "EVBACKEND_ALL" |
833 | .IX Item "EVBACKEND_ALL" |
696 | Try all backends (even potentially broken ones that wouldn't be tried |
834 | Try all backends (even potentially broken ones that wouldn't be tried |
697 | with \f(CW\*(C`EVFLAG_AUTO\*(C'\fR). Since this is a mask, you can do stuff such as |
835 | with \f(CW\*(C`EVFLAG_AUTO\*(C'\fR). Since this is a mask, you can do stuff such as |
698 | \&\f(CW\*(C`EVBACKEND_ALL & ~EVBACKEND_KQUEUE\*(C'\fR. |
836 | \&\f(CW\*(C`EVBACKEND_ALL & ~EVBACKEND_KQUEUE\*(C'\fR. |
699 | .Sp |
837 | .Sp |
700 | It is definitely not recommended to use this flag. |
838 | It is definitely not recommended to use this flag, use whatever |
|
|
839 | \&\f(CW\*(C`ev_recommended_backends ()\*(C'\fR returns, or simply do not specify a backend |
|
|
840 | at all. |
|
|
841 | .ie n .IP """EVBACKEND_MASK""" 4 |
|
|
842 | .el .IP "\f(CWEVBACKEND_MASK\fR" 4 |
|
|
843 | .IX Item "EVBACKEND_MASK" |
|
|
844 | Not a backend at all, but a mask to select all backend bits from a |
|
|
845 | \&\f(CW\*(C`flags\*(C'\fR value, in case you want to mask out any backends from a flags |
|
|
846 | value (e.g. when modifying the \f(CW\*(C`LIBEV_FLAGS\*(C'\fR environment variable). |
701 | .RE |
847 | .RE |
702 | .RS 4 |
848 | .RS 4 |
703 | .Sp |
849 | .Sp |
704 | If one or more of the backend flags are or'ed into the flags value, |
850 | If one or more of the backend flags are or'ed into the flags value, |
705 | then only these backends will be tried (in the reverse order as listed |
851 | then only these backends will be tried (in the reverse order as listed |
… | |
… | |
717 | Example: Use whatever libev has to offer, but make sure that kqueue is |
863 | Example: Use whatever libev has to offer, but make sure that kqueue is |
718 | used if available. |
864 | used if available. |
719 | .Sp |
865 | .Sp |
720 | .Vb 1 |
866 | .Vb 1 |
721 | \& struct ev_loop *loop = ev_loop_new (ev_recommended_backends () | EVBACKEND_KQUEUE); |
867 | \& struct ev_loop *loop = ev_loop_new (ev_recommended_backends () | EVBACKEND_KQUEUE); |
|
|
868 | .Ve |
|
|
869 | .Sp |
|
|
870 | Example: Similarly, on linux, you mgiht want to take advantage of the |
|
|
871 | linux aio backend if possible, but fall back to something else if that |
|
|
872 | isn't available. |
|
|
873 | .Sp |
|
|
874 | .Vb 1 |
|
|
875 | \& struct ev_loop *loop = ev_loop_new (ev_recommended_backends () | EVBACKEND_LINUXAIO); |
722 | .Ve |
876 | .Ve |
723 | .RE |
877 | .RE |
724 | .IP "ev_loop_destroy (loop)" 4 |
878 | .IP "ev_loop_destroy (loop)" 4 |
725 | .IX Item "ev_loop_destroy (loop)" |
879 | .IX Item "ev_loop_destroy (loop)" |
726 | Destroys an event loop object (frees all memory and kernel state |
880 | Destroys an event loop object (frees all memory and kernel state |
… | |
… | |
738 | This function is normally used on loop objects allocated by |
892 | This function is normally used on loop objects allocated by |
739 | \&\f(CW\*(C`ev_loop_new\*(C'\fR, but it can also be used on the default loop returned by |
893 | \&\f(CW\*(C`ev_loop_new\*(C'\fR, but it can also be used on the default loop returned by |
740 | \&\f(CW\*(C`ev_default_loop\*(C'\fR, in which case it is not thread-safe. |
894 | \&\f(CW\*(C`ev_default_loop\*(C'\fR, in which case it is not thread-safe. |
741 | .Sp |
895 | .Sp |
742 | Note that it is not advisable to call this function on the default loop |
896 | Note that it is not advisable to call this function on the default loop |
743 | except in the rare occasion where you really need to free it's resources. |
897 | except in the rare occasion where you really need to free its resources. |
744 | If you need dynamically allocated loops it is better to use \f(CW\*(C`ev_loop_new\*(C'\fR |
898 | If you need dynamically allocated loops it is better to use \f(CW\*(C`ev_loop_new\*(C'\fR |
745 | and \f(CW\*(C`ev_loop_destroy\*(C'\fR. |
899 | and \f(CW\*(C`ev_loop_destroy\*(C'\fR. |
746 | .IP "ev_loop_fork (loop)" 4 |
900 | .IP "ev_loop_fork (loop)" 4 |
747 | .IX Item "ev_loop_fork (loop)" |
901 | .IX Item "ev_loop_fork (loop)" |
748 | This function sets a flag that causes subsequent \f(CW\*(C`ev_run\*(C'\fR iterations to |
902 | This function sets a flag that causes subsequent \f(CW\*(C`ev_run\*(C'\fR iterations |
749 | reinitialise the kernel state for backends that have one. Despite the |
903 | to reinitialise the kernel state for backends that have one. Despite |
750 | name, you can call it anytime, but it makes most sense after forking, in |
904 | the name, you can call it anytime you are allowed to start or stop |
751 | the child process. You \fImust\fR call it (or use \f(CW\*(C`EVFLAG_FORKCHECK\*(C'\fR) in the |
905 | watchers (except inside an \f(CW\*(C`ev_prepare\*(C'\fR callback), but it makes most |
752 | child before resuming or calling \f(CW\*(C`ev_run\*(C'\fR. |
906 | sense after forking, in the child process. You \fImust\fR call it (or use |
|
|
907 | \&\f(CW\*(C`EVFLAG_FORKCHECK\*(C'\fR) in the child before resuming or calling \f(CW\*(C`ev_run\*(C'\fR. |
753 | .Sp |
908 | .Sp |
|
|
909 | In addition, if you want to reuse a loop (via this function or |
|
|
910 | \&\f(CW\*(C`EVFLAG_FORKCHECK\*(C'\fR), you \fIalso\fR have to ignore \f(CW\*(C`SIGPIPE\*(C'\fR. |
|
|
911 | .Sp |
754 | Again, you \fIhave\fR to call it on \fIany\fR loop that you want to re-use after |
912 | Again, you \fIhave\fR to call it on \fIany\fR loop that you want to re-use after |
755 | a fork, \fIeven if you do not plan to use the loop in the parent\fR. This is |
913 | a fork, \fIeven if you do not plan to use the loop in the parent\fR. This is |
756 | because some kernel interfaces *cough* \fIkqueue\fR *cough* do funny things |
914 | because some kernel interfaces *cough* \fIkqueue\fR *cough* do funny things |
757 | during fork. |
915 | during fork. |
758 | .Sp |
916 | .Sp |
759 | On the other hand, you only need to call this function in the child |
917 | On the other hand, you only need to call this function in the child |
… | |
… | |
794 | \&\f(CW\*(C`ev_prepare\*(C'\fR and \f(CW\*(C`ev_check\*(C'\fR calls \- and is incremented between the |
952 | \&\f(CW\*(C`ev_prepare\*(C'\fR and \f(CW\*(C`ev_check\*(C'\fR calls \- and is incremented between the |
795 | prepare and check phases. |
953 | prepare and check phases. |
796 | .IP "unsigned int ev_depth (loop)" 4 |
954 | .IP "unsigned int ev_depth (loop)" 4 |
797 | .IX Item "unsigned int ev_depth (loop)" |
955 | .IX Item "unsigned int ev_depth (loop)" |
798 | Returns the number of times \f(CW\*(C`ev_run\*(C'\fR was entered minus the number of |
956 | Returns the number of times \f(CW\*(C`ev_run\*(C'\fR was entered minus the number of |
799 | times \f(CW\*(C`ev_run\*(C'\fR was exited, in other words, the recursion depth. |
957 | times \f(CW\*(C`ev_run\*(C'\fR was exited normally, in other words, the recursion depth. |
800 | .Sp |
958 | .Sp |
801 | Outside \f(CW\*(C`ev_run\*(C'\fR, this number is zero. In a callback, this number is |
959 | Outside \f(CW\*(C`ev_run\*(C'\fR, this number is zero. In a callback, this number is |
802 | \&\f(CW1\fR, unless \f(CW\*(C`ev_run\*(C'\fR was invoked recursively (or from another thread), |
960 | \&\f(CW1\fR, unless \f(CW\*(C`ev_run\*(C'\fR was invoked recursively (or from another thread), |
803 | in which case it is higher. |
961 | in which case it is higher. |
804 | .Sp |
962 | .Sp |
805 | Leaving \f(CW\*(C`ev_run\*(C'\fR abnormally (setjmp/longjmp, cancelling the thread |
963 | Leaving \f(CW\*(C`ev_run\*(C'\fR abnormally (setjmp/longjmp, cancelling the thread, |
806 | etc.), doesn't count as \*(L"exit\*(R" \- consider this as a hint to avoid such |
964 | throwing an exception etc.), doesn't count as \*(L"exit\*(R" \- consider this |
807 | ungentleman-like behaviour unless it's really convenient. |
965 | as a hint to avoid such ungentleman-like behaviour unless it's really |
|
|
966 | convenient, in which case it is fully supported. |
808 | .IP "unsigned int ev_backend (loop)" 4 |
967 | .IP "unsigned int ev_backend (loop)" 4 |
809 | .IX Item "unsigned int ev_backend (loop)" |
968 | .IX Item "unsigned int ev_backend (loop)" |
810 | Returns one of the \f(CW\*(C`EVBACKEND_*\*(C'\fR flags indicating the event backend in |
969 | Returns one of the \f(CW\*(C`EVBACKEND_*\*(C'\fR flags indicating the event backend in |
811 | use. |
970 | use. |
812 | .IP "ev_tstamp ev_now (loop)" 4 |
971 | .IP "ev_tstamp ev_now (loop)" 4 |
… | |
… | |
852 | given loop other than \f(CW\*(C`ev_resume\*(C'\fR, and you \fBmust not\fR call \f(CW\*(C`ev_resume\*(C'\fR |
1011 | given loop other than \f(CW\*(C`ev_resume\*(C'\fR, and you \fBmust not\fR call \f(CW\*(C`ev_resume\*(C'\fR |
853 | without a previous call to \f(CW\*(C`ev_suspend\*(C'\fR. |
1012 | without a previous call to \f(CW\*(C`ev_suspend\*(C'\fR. |
854 | .Sp |
1013 | .Sp |
855 | Calling \f(CW\*(C`ev_suspend\*(C'\fR/\f(CW\*(C`ev_resume\*(C'\fR has the side effect of updating the |
1014 | Calling \f(CW\*(C`ev_suspend\*(C'\fR/\f(CW\*(C`ev_resume\*(C'\fR has the side effect of updating the |
856 | event loop time (see \f(CW\*(C`ev_now_update\*(C'\fR). |
1015 | event loop time (see \f(CW\*(C`ev_now_update\*(C'\fR). |
857 | .IP "ev_run (loop, int flags)" 4 |
1016 | .IP "bool ev_run (loop, int flags)" 4 |
858 | .IX Item "ev_run (loop, int flags)" |
1017 | .IX Item "bool ev_run (loop, int flags)" |
859 | Finally, this is it, the event handler. This function usually is called |
1018 | Finally, this is it, the event handler. This function usually is called |
860 | after you have initialised all your watchers and you want to start |
1019 | after you have initialised all your watchers and you want to start |
861 | handling events. It will ask the operating system for any new events, call |
1020 | handling events. It will ask the operating system for any new events, call |
862 | the watcher callbacks, an then repeat the whole process indefinitely: This |
1021 | the watcher callbacks, and then repeat the whole process indefinitely: This |
863 | is why event loops are called \fIloops\fR. |
1022 | is why event loops are called \fIloops\fR. |
864 | .Sp |
1023 | .Sp |
865 | If the flags argument is specified as \f(CW0\fR, it will keep handling events |
1024 | If the flags argument is specified as \f(CW0\fR, it will keep handling events |
866 | until either no event watchers are active anymore or \f(CW\*(C`ev_break\*(C'\fR was |
1025 | until either no event watchers are active anymore or \f(CW\*(C`ev_break\*(C'\fR was |
867 | called. |
1026 | called. |
|
|
1027 | .Sp |
|
|
1028 | The return value is false if there are no more active watchers (which |
|
|
1029 | usually means \*(L"all jobs done\*(R" or \*(L"deadlock\*(R"), and true in all other cases |
|
|
1030 | (which usually means " you should call \f(CW\*(C`ev_run\*(C'\fR again"). |
868 | .Sp |
1031 | .Sp |
869 | Please note that an explicit \f(CW\*(C`ev_break\*(C'\fR is usually better than |
1032 | Please note that an explicit \f(CW\*(C`ev_break\*(C'\fR is usually better than |
870 | relying on all watchers to be stopped when deciding when a program has |
1033 | relying on all watchers to be stopped when deciding when a program has |
871 | finished (especially in interactive programs), but having a program |
1034 | finished (especially in interactive programs), but having a program |
872 | that automatically loops as long as it has to and no longer by virtue |
1035 | that automatically loops as long as it has to and no longer by virtue |
873 | of relying on its watchers stopping correctly, that is truly a thing of |
1036 | of relying on its watchers stopping correctly, that is truly a thing of |
874 | beauty. |
1037 | beauty. |
875 | .Sp |
1038 | .Sp |
|
|
1039 | This function is \fImostly\fR exception-safe \- you can break out of a |
|
|
1040 | \&\f(CW\*(C`ev_run\*(C'\fR call by calling \f(CW\*(C`longjmp\*(C'\fR in a callback, throwing a \*(C+ |
|
|
1041 | exception and so on. This does not decrement the \f(CW\*(C`ev_depth\*(C'\fR value, nor |
|
|
1042 | will it clear any outstanding \f(CW\*(C`EVBREAK_ONE\*(C'\fR breaks. |
|
|
1043 | .Sp |
876 | A flags value of \f(CW\*(C`EVRUN_NOWAIT\*(C'\fR will look for new events, will handle |
1044 | A flags value of \f(CW\*(C`EVRUN_NOWAIT\*(C'\fR will look for new events, will handle |
877 | those events and any already outstanding ones, but will not wait and |
1045 | those events and any already outstanding ones, but will not wait and |
878 | block your process in case there are no events and will return after one |
1046 | block your process in case there are no events and will return after one |
879 | iteration of the loop. This is sometimes useful to poll and handle new |
1047 | iteration of the loop. This is sometimes useful to poll and handle new |
880 | events while doing lengthy calculations, to keep the program responsive. |
1048 | events while doing lengthy calculations, to keep the program responsive. |
… | |
… | |
889 | This is useful if you are waiting for some external event in conjunction |
1057 | This is useful if you are waiting for some external event in conjunction |
890 | with something not expressible using other libev watchers (i.e. "roll your |
1058 | with something not expressible using other libev watchers (i.e. "roll your |
891 | 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 |
1059 | 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 |
892 | usually a better approach for this kind of thing. |
1060 | usually a better approach for this kind of thing. |
893 | .Sp |
1061 | .Sp |
894 | Here are the gory details of what \f(CW\*(C`ev_run\*(C'\fR does: |
1062 | Here are the gory details of what \f(CW\*(C`ev_run\*(C'\fR does (this is for your |
|
|
1063 | understanding, not a guarantee that things will work exactly like this in |
|
|
1064 | future versions): |
895 | .Sp |
1065 | .Sp |
896 | .Vb 10 |
1066 | .Vb 10 |
897 | \& \- Increment loop depth. |
1067 | \& \- Increment loop depth. |
898 | \& \- Reset the ev_break status. |
1068 | \& \- Reset the ev_break status. |
899 | \& \- Before the first iteration, call any pending watchers. |
1069 | \& \- Before the first iteration, call any pending watchers. |
… | |
… | |
917 | \& \- Queue all expired timers. |
1087 | \& \- Queue all expired timers. |
918 | \& \- Queue all expired periodics. |
1088 | \& \- Queue all expired periodics. |
919 | \& \- Queue all idle watchers with priority higher than that of pending events. |
1089 | \& \- Queue all idle watchers with priority higher than that of pending events. |
920 | \& \- Queue all check watchers. |
1090 | \& \- Queue all check watchers. |
921 | \& \- Call all queued watchers in reverse order (i.e. check watchers first). |
1091 | \& \- Call all queued watchers in reverse order (i.e. check watchers first). |
922 | \& Signals and child watchers are implemented as I/O watchers, and will |
1092 | \& Signals, async and child watchers are implemented as I/O watchers, and |
923 | \& be handled here by queueing them when their watcher gets executed. |
1093 | \& will be handled here by queueing them when their watcher gets executed. |
924 | \& \- If ev_break has been called, or EVRUN_ONCE or EVRUN_NOWAIT |
1094 | \& \- If ev_break has been called, or EVRUN_ONCE or EVRUN_NOWAIT |
925 | \& were used, or there are no active watchers, goto FINISH, otherwise |
1095 | \& were used, or there are no active watchers, goto FINISH, otherwise |
926 | \& continue with step LOOP. |
1096 | \& continue with step LOOP. |
927 | \& FINISH: |
1097 | \& FINISH: |
928 | \& \- Reset the ev_break status iff it was EVBREAK_ONE. |
1098 | \& \- Reset the ev_break status iff it was EVBREAK_ONE. |
… | |
… | |
935 | .Sp |
1105 | .Sp |
936 | .Vb 4 |
1106 | .Vb 4 |
937 | \& ... queue jobs here, make sure they register event watchers as long |
1107 | \& ... queue jobs here, make sure they register event watchers as long |
938 | \& ... as they still have work to do (even an idle watcher will do..) |
1108 | \& ... as they still have work to do (even an idle watcher will do..) |
939 | \& ev_run (my_loop, 0); |
1109 | \& ev_run (my_loop, 0); |
940 | \& ... jobs done or somebody called unloop. yeah! |
1110 | \& ... jobs done or somebody called break. yeah! |
941 | .Ve |
1111 | .Ve |
942 | .IP "ev_break (loop, how)" 4 |
1112 | .IP "ev_break (loop, how)" 4 |
943 | .IX Item "ev_break (loop, how)" |
1113 | .IX Item "ev_break (loop, how)" |
944 | Can be used to make a call to \f(CW\*(C`ev_run\*(C'\fR return early (but only after it |
1114 | Can be used to make a call to \f(CW\*(C`ev_run\*(C'\fR return early (but only after it |
945 | has processed all outstanding events). The \f(CW\*(C`how\*(C'\fR argument must be either |
1115 | has processed all outstanding events). The \f(CW\*(C`how\*(C'\fR argument must be either |
946 | \&\f(CW\*(C`EVBREAK_ONE\*(C'\fR, which will make the innermost \f(CW\*(C`ev_run\*(C'\fR call return, or |
1116 | \&\f(CW\*(C`EVBREAK_ONE\*(C'\fR, which will make the innermost \f(CW\*(C`ev_run\*(C'\fR call return, or |
947 | \&\f(CW\*(C`EVBREAK_ALL\*(C'\fR, which will make all nested \f(CW\*(C`ev_run\*(C'\fR calls return. |
1117 | \&\f(CW\*(C`EVBREAK_ALL\*(C'\fR, which will make all nested \f(CW\*(C`ev_run\*(C'\fR calls return. |
948 | .Sp |
1118 | .Sp |
949 | This \*(L"break state\*(R" will be cleared when entering \f(CW\*(C`ev_run\*(C'\fR again. |
1119 | This \*(L"break state\*(R" will be cleared on the next call to \f(CW\*(C`ev_run\*(C'\fR. |
950 | .Sp |
1120 | .Sp |
951 | It is safe to call \f(CW\*(C`ev_break\*(C'\fR from outside any \f(CW\*(C`ev_run\*(C'\fR calls, too. |
1121 | 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 |
|
|
1122 | which case it will have no effect. |
952 | .IP "ev_ref (loop)" 4 |
1123 | .IP "ev_ref (loop)" 4 |
953 | .IX Item "ev_ref (loop)" |
1124 | .IX Item "ev_ref (loop)" |
954 | .PD 0 |
1125 | .PD 0 |
955 | .IP "ev_unref (loop)" 4 |
1126 | .IP "ev_unref (loop)" 4 |
956 | .IX Item "ev_unref (loop)" |
1127 | .IX Item "ev_unref (loop)" |
… | |
… | |
979 | .Sp |
1150 | .Sp |
980 | .Vb 4 |
1151 | .Vb 4 |
981 | \& ev_signal exitsig; |
1152 | \& ev_signal exitsig; |
982 | \& ev_signal_init (&exitsig, sig_cb, SIGINT); |
1153 | \& ev_signal_init (&exitsig, sig_cb, SIGINT); |
983 | \& ev_signal_start (loop, &exitsig); |
1154 | \& ev_signal_start (loop, &exitsig); |
984 | \& evf_unref (loop); |
1155 | \& ev_unref (loop); |
985 | .Ve |
1156 | .Ve |
986 | .Sp |
1157 | .Sp |
987 | Example: For some weird reason, unregister the above signal handler again. |
1158 | Example: For some weird reason, unregister the above signal handler again. |
988 | .Sp |
1159 | .Sp |
989 | .Vb 2 |
1160 | .Vb 2 |
… | |
… | |
1013 | overhead for the actual polling but can deliver many events at once. |
1184 | overhead for the actual polling but can deliver many events at once. |
1014 | .Sp |
1185 | .Sp |
1015 | By setting a higher \fIio collect interval\fR you allow libev to spend more |
1186 | By setting a higher \fIio collect interval\fR you allow libev to spend more |
1016 | time collecting I/O events, so you can handle more events per iteration, |
1187 | time collecting I/O events, so you can handle more events per iteration, |
1017 | at the cost of increasing latency. Timeouts (both \f(CW\*(C`ev_periodic\*(C'\fR and |
1188 | at the cost of increasing latency. Timeouts (both \f(CW\*(C`ev_periodic\*(C'\fR and |
1018 | \&\f(CW\*(C`ev_timer\*(C'\fR) will be not affected. Setting this to a non-null value will |
1189 | \&\f(CW\*(C`ev_timer\*(C'\fR) will not be affected. Setting this to a non-null value will |
1019 | introduce an additional \f(CW\*(C`ev_sleep ()\*(C'\fR call into most loop iterations. The |
1190 | introduce an additional \f(CW\*(C`ev_sleep ()\*(C'\fR call into most loop iterations. The |
1020 | sleep time ensures that libev will not poll for I/O events more often then |
1191 | sleep time ensures that libev will not poll for I/O events more often then |
1021 | once per this interval, on average. |
1192 | once per this interval, on average (as long as the host time resolution is |
|
|
1193 | good enough). |
1022 | .Sp |
1194 | .Sp |
1023 | Likewise, by setting a higher \fItimeout collect interval\fR you allow libev |
1195 | Likewise, by setting a higher \fItimeout collect interval\fR you allow libev |
1024 | to spend more time collecting timeouts, at the expense of increased |
1196 | to spend more time collecting timeouts, at the expense of increased |
1025 | latency/jitter/inexactness (the watcher callback will be called |
1197 | latency/jitter/inexactness (the watcher callback will be called |
1026 | later). \f(CW\*(C`ev_io\*(C'\fR watchers will not be affected. Setting this to a non-null |
1198 | later). \f(CW\*(C`ev_io\*(C'\fR watchers will not be affected. Setting this to a non-null |
… | |
… | |
1070 | this callback instead. This is useful, for example, when you want to |
1242 | this callback instead. This is useful, for example, when you want to |
1071 | invoke the actual watchers inside another context (another thread etc.). |
1243 | invoke the actual watchers inside another context (another thread etc.). |
1072 | .Sp |
1244 | .Sp |
1073 | If you want to reset the callback, use \f(CW\*(C`ev_invoke_pending\*(C'\fR as new |
1245 | If you want to reset the callback, use \f(CW\*(C`ev_invoke_pending\*(C'\fR as new |
1074 | callback. |
1246 | callback. |
1075 | .IP "ev_set_loop_release_cb (loop, void (*release)(\s-1EV_P\s0), void (*acquire)(\s-1EV_P\s0))" 4 |
1247 | .IP "ev_set_loop_release_cb (loop, void (*release)(\s-1EV_P\s0) throw (), void (*acquire)(\s-1EV_P\s0) throw ())" 4 |
1076 | .IX Item "ev_set_loop_release_cb (loop, void (*release)(EV_P), void (*acquire)(EV_P))" |
1248 | .IX Item "ev_set_loop_release_cb (loop, void (*release)(EV_P) throw (), void (*acquire)(EV_P) throw ())" |
1077 | Sometimes you want to share the same loop between multiple threads. This |
1249 | Sometimes you want to share the same loop between multiple threads. This |
1078 | can be done relatively simply by putting mutex_lock/unlock calls around |
1250 | can be done relatively simply by putting mutex_lock/unlock calls around |
1079 | each call to a libev function. |
1251 | each call to a libev function. |
1080 | .Sp |
1252 | .Sp |
1081 | However, \f(CW\*(C`ev_run\*(C'\fR can run an indefinite time, so it is not feasible |
1253 | However, \f(CW\*(C`ev_run\*(C'\fR can run an indefinite time, so it is not feasible |
1082 | to wait for it to return. One way around this is to wake up the event |
1254 | to wait for it to return. One way around this is to wake up the event |
1083 | loop via \f(CW\*(C`ev_break\*(C'\fR and \f(CW\*(C`av_async_send\*(C'\fR, another way is to set these |
1255 | loop via \f(CW\*(C`ev_break\*(C'\fR and \f(CW\*(C`ev_async_send\*(C'\fR, another way is to set these |
1084 | \&\fIrelease\fR and \fIacquire\fR callbacks on the loop. |
1256 | \&\fIrelease\fR and \fIacquire\fR callbacks on the loop. |
1085 | .Sp |
1257 | .Sp |
1086 | When set, then \f(CW\*(C`release\*(C'\fR will be called just before the thread is |
1258 | When set, then \f(CW\*(C`release\*(C'\fR will be called just before the thread is |
1087 | suspended waiting for new events, and \f(CW\*(C`acquire\*(C'\fR is called just |
1259 | suspended waiting for new events, and \f(CW\*(C`acquire\*(C'\fR is called just |
1088 | afterwards. |
1260 | afterwards. |
… | |
… | |
1103 | See also the locking example in the \f(CW\*(C`THREADS\*(C'\fR section later in this |
1275 | See also the locking example in the \f(CW\*(C`THREADS\*(C'\fR section later in this |
1104 | document. |
1276 | document. |
1105 | .IP "ev_set_userdata (loop, void *data)" 4 |
1277 | .IP "ev_set_userdata (loop, void *data)" 4 |
1106 | .IX Item "ev_set_userdata (loop, void *data)" |
1278 | .IX Item "ev_set_userdata (loop, void *data)" |
1107 | .PD 0 |
1279 | .PD 0 |
1108 | .IP "ev_userdata (loop)" 4 |
1280 | .IP "void *ev_userdata (loop)" 4 |
1109 | .IX Item "ev_userdata (loop)" |
1281 | .IX Item "void *ev_userdata (loop)" |
1110 | .PD |
1282 | .PD |
1111 | Set and retrieve a single \f(CW\*(C`void *\*(C'\fR associated with a loop. When |
1283 | Set and retrieve a single \f(CW\*(C`void *\*(C'\fR associated with a loop. When |
1112 | \&\f(CW\*(C`ev_set_userdata\*(C'\fR has never been called, then \f(CW\*(C`ev_userdata\*(C'\fR returns |
1284 | \&\f(CW\*(C`ev_set_userdata\*(C'\fR has never been called, then \f(CW\*(C`ev_userdata\*(C'\fR returns |
1113 | \&\f(CW0.\fR |
1285 | \&\f(CW0\fR. |
1114 | .Sp |
1286 | .Sp |
1115 | These two functions can be used to associate arbitrary data with a loop, |
1287 | These two functions can be used to associate arbitrary data with a loop, |
1116 | and are intended solely for the \f(CW\*(C`invoke_pending_cb\*(C'\fR, \f(CW\*(C`release\*(C'\fR and |
1288 | and are intended solely for the \f(CW\*(C`invoke_pending_cb\*(C'\fR, \f(CW\*(C`release\*(C'\fR and |
1117 | \&\f(CW\*(C`acquire\*(C'\fR callbacks described above, but of course can be (ab\-)used for |
1289 | \&\f(CW\*(C`acquire\*(C'\fR callbacks described above, but of course can be (ab\-)used for |
1118 | any other purpose as well. |
1290 | any other purpose as well. |
… | |
… | |
1177 | with a watcher-specific start function (\f(CW\*(C`ev_TYPE_start (loop, watcher |
1349 | with a watcher-specific start function (\f(CW\*(C`ev_TYPE_start (loop, watcher |
1178 | *)\*(C'\fR), and you can stop watching for events at any time by calling the |
1350 | *)\*(C'\fR), and you can stop watching for events at any time by calling the |
1179 | corresponding stop function (\f(CW\*(C`ev_TYPE_stop (loop, watcher *)\*(C'\fR. |
1351 | corresponding stop function (\f(CW\*(C`ev_TYPE_stop (loop, watcher *)\*(C'\fR. |
1180 | .PP |
1352 | .PP |
1181 | As long as your watcher is active (has been started but not stopped) you |
1353 | As long as your watcher is active (has been started but not stopped) you |
1182 | must not touch the values stored in it. Most specifically you must never |
1354 | must not touch the values stored in it except when explicitly documented |
1183 | reinitialise it or call its \f(CW\*(C`ev_TYPE_set\*(C'\fR macro. |
1355 | otherwise. Most specifically you must never reinitialise it or call its |
|
|
1356 | \&\f(CW\*(C`ev_TYPE_set\*(C'\fR macro. |
1184 | .PP |
1357 | .PP |
1185 | Each and every callback receives the event loop pointer as first, the |
1358 | Each and every callback receives the event loop pointer as first, the |
1186 | registered watcher structure as second, and a bitset of received events as |
1359 | registered watcher structure as second, and a bitset of received events as |
1187 | third argument. |
1360 | third argument. |
1188 | .PP |
1361 | .PP |
… | |
… | |
1229 | .PD 0 |
1402 | .PD 0 |
1230 | .ie n .IP """EV_CHECK""" 4 |
1403 | .ie n .IP """EV_CHECK""" 4 |
1231 | .el .IP "\f(CWEV_CHECK\fR" 4 |
1404 | .el .IP "\f(CWEV_CHECK\fR" 4 |
1232 | .IX Item "EV_CHECK" |
1405 | .IX Item "EV_CHECK" |
1233 | .PD |
1406 | .PD |
1234 | All \f(CW\*(C`ev_prepare\*(C'\fR watchers are invoked just \fIbefore\fR \f(CW\*(C`ev_run\*(C'\fR starts |
1407 | All \f(CW\*(C`ev_prepare\*(C'\fR watchers are invoked just \fIbefore\fR \f(CW\*(C`ev_run\*(C'\fR starts to |
1235 | to gather new events, and all \f(CW\*(C`ev_check\*(C'\fR watchers are invoked just after |
1408 | gather new events, and all \f(CW\*(C`ev_check\*(C'\fR watchers are queued (not invoked) |
1236 | \&\f(CW\*(C`ev_run\*(C'\fR has gathered them, but before it invokes any callbacks for any |
1409 | just after \f(CW\*(C`ev_run\*(C'\fR has gathered them, but before it queues any callbacks |
|
|
1410 | for any received events. That means \f(CW\*(C`ev_prepare\*(C'\fR watchers are the last |
|
|
1411 | watchers invoked before the event loop sleeps or polls for new events, and |
|
|
1412 | \&\f(CW\*(C`ev_check\*(C'\fR watchers will be invoked before any other watchers of the same |
|
|
1413 | or lower priority within an event loop iteration. |
|
|
1414 | .Sp |
1237 | received events. Callbacks of both watcher types can start and stop as |
1415 | Callbacks of both watcher types can start and stop as many watchers as |
1238 | many watchers as they want, and all of them will be taken into account |
1416 | they want, and all of them will be taken into account (for example, a |
1239 | (for example, a \f(CW\*(C`ev_prepare\*(C'\fR watcher might start an idle watcher to keep |
1417 | \&\f(CW\*(C`ev_prepare\*(C'\fR watcher might start an idle watcher to keep \f(CW\*(C`ev_run\*(C'\fR from |
1240 | \&\f(CW\*(C`ev_run\*(C'\fR from blocking). |
1418 | blocking). |
1241 | .ie n .IP """EV_EMBED""" 4 |
1419 | .ie n .IP """EV_EMBED""" 4 |
1242 | .el .IP "\f(CWEV_EMBED\fR" 4 |
1420 | .el .IP "\f(CWEV_EMBED\fR" 4 |
1243 | .IX Item "EV_EMBED" |
1421 | .IX Item "EV_EMBED" |
1244 | The embedded event loop specified in the \f(CW\*(C`ev_embed\*(C'\fR watcher needs attention. |
1422 | The embedded event loop specified in the \f(CW\*(C`ev_embed\*(C'\fR watcher needs attention. |
1245 | .ie n .IP """EV_FORK""" 4 |
1423 | .ie n .IP """EV_FORK""" 4 |
… | |
… | |
1274 | bug in your program. |
1452 | bug in your program. |
1275 | .Sp |
1453 | .Sp |
1276 | Libev will usually signal a few \*(L"dummy\*(R" events together with an error, for |
1454 | Libev will usually signal a few \*(L"dummy\*(R" events together with an error, for |
1277 | example it might indicate that a fd is readable or writable, and if your |
1455 | example it might indicate that a fd is readable or writable, and if your |
1278 | callbacks is well-written it can just attempt the operation and cope with |
1456 | callbacks is well-written it can just attempt the operation and cope with |
1279 | the error from \fIread()\fR or \fIwrite()\fR. This will not work in multi-threaded |
1457 | the error from \fBread()\fR or \fBwrite()\fR. This will not work in multi-threaded |
1280 | programs, though, as the fd could already be closed and reused for another |
1458 | programs, though, as the fd could already be closed and reused for another |
1281 | thing, so beware. |
1459 | thing, so beware. |
1282 | .SS "\s-1GENERIC\s0 \s-1WATCHER\s0 \s-1FUNCTIONS\s0" |
1460 | .SS "\s-1GENERIC WATCHER FUNCTIONS\s0" |
1283 | .IX Subsection "GENERIC WATCHER FUNCTIONS" |
1461 | .IX Subsection "GENERIC WATCHER FUNCTIONS" |
1284 | .ie n .IP """ev_init"" (ev_TYPE *watcher, callback)" 4 |
1462 | .ie n .IP """ev_init"" (ev_TYPE *watcher, callback)" 4 |
1285 | .el .IP "\f(CWev_init\fR (ev_TYPE *watcher, callback)" 4 |
1463 | .el .IP "\f(CWev_init\fR (ev_TYPE *watcher, callback)" 4 |
1286 | .IX Item "ev_init (ev_TYPE *watcher, callback)" |
1464 | .IX Item "ev_init (ev_TYPE *watcher, callback)" |
1287 | This macro initialises the generic portion of a watcher. The contents |
1465 | This macro initialises the generic portion of a watcher. The contents |
… | |
… | |
1354 | therefore a good idea to always call its \f(CW\*(C`ev_TYPE_stop\*(C'\fR function. |
1532 | therefore a good idea to always call its \f(CW\*(C`ev_TYPE_stop\*(C'\fR function. |
1355 | .IP "bool ev_is_active (ev_TYPE *watcher)" 4 |
1533 | .IP "bool ev_is_active (ev_TYPE *watcher)" 4 |
1356 | .IX Item "bool ev_is_active (ev_TYPE *watcher)" |
1534 | .IX Item "bool ev_is_active (ev_TYPE *watcher)" |
1357 | Returns a true value iff the watcher is active (i.e. it has been started |
1535 | Returns a true value iff the watcher is active (i.e. it has been started |
1358 | and not yet been stopped). As long as a watcher is active you must not modify |
1536 | and not yet been stopped). As long as a watcher is active you must not modify |
1359 | it. |
1537 | it unless documented otherwise. |
|
|
1538 | .Sp |
|
|
1539 | Obviously, it is safe to call this on an active watcher, or actually any |
|
|
1540 | watcher that is initialised. |
1360 | .IP "bool ev_is_pending (ev_TYPE *watcher)" 4 |
1541 | .IP "bool ev_is_pending (ev_TYPE *watcher)" 4 |
1361 | .IX Item "bool ev_is_pending (ev_TYPE *watcher)" |
1542 | .IX Item "bool ev_is_pending (ev_TYPE *watcher)" |
1362 | Returns a true value iff the watcher is pending, (i.e. it has outstanding |
1543 | Returns a true value iff the watcher is pending, (i.e. it has outstanding |
1363 | events but its callback has not yet been invoked). As long as a watcher |
1544 | events but its callback has not yet been invoked). As long as a watcher |
1364 | is pending (but not active) you must not call an init function on it (but |
1545 | is pending (but not active) you must not call an init function on it (but |
1365 | \&\f(CW\*(C`ev_TYPE_set\*(C'\fR is safe), you must not change its priority, and you must |
1546 | \&\f(CW\*(C`ev_TYPE_set\*(C'\fR is safe), you must not change its priority, and you must |
1366 | make sure the watcher is available to libev (e.g. you cannot \f(CW\*(C`free ()\*(C'\fR |
1547 | make sure the watcher is available to libev (e.g. you cannot \f(CW\*(C`free ()\*(C'\fR |
1367 | it). |
1548 | it). |
|
|
1549 | .Sp |
|
|
1550 | It is safe to call this on any watcher in any state as long as it is |
|
|
1551 | initialised. |
1368 | .IP "callback ev_cb (ev_TYPE *watcher)" 4 |
1552 | .IP "callback ev_cb (ev_TYPE *watcher)" 4 |
1369 | .IX Item "callback ev_cb (ev_TYPE *watcher)" |
1553 | .IX Item "callback ev_cb (ev_TYPE *watcher)" |
1370 | Returns the callback currently set on the watcher. |
1554 | Returns the callback currently set on the watcher. |
1371 | .IP "ev_cb_set (ev_TYPE *watcher, callback)" 4 |
1555 | .IP "ev_set_cb (ev_TYPE *watcher, callback)" 4 |
1372 | .IX Item "ev_cb_set (ev_TYPE *watcher, callback)" |
1556 | .IX Item "ev_set_cb (ev_TYPE *watcher, callback)" |
1373 | Change the callback. You can change the callback at virtually any time |
1557 | Change the callback. You can change the callback at virtually any time |
1374 | (modulo threads). |
1558 | (modulo threads). |
1375 | .IP "ev_set_priority (ev_TYPE *watcher, int priority)" 4 |
1559 | .IP "ev_set_priority (ev_TYPE *watcher, int priority)" 4 |
1376 | .IX Item "ev_set_priority (ev_TYPE *watcher, int priority)" |
1560 | .IX Item "ev_set_priority (ev_TYPE *watcher, int priority)" |
1377 | .PD 0 |
1561 | .PD 0 |
… | |
… | |
1385 | from being executed (except for \f(CW\*(C`ev_idle\*(C'\fR watchers). |
1569 | from being executed (except for \f(CW\*(C`ev_idle\*(C'\fR watchers). |
1386 | .Sp |
1570 | .Sp |
1387 | If you need to suppress invocation when higher priority events are pending |
1571 | If you need to suppress invocation when higher priority events are pending |
1388 | you need to look at \f(CW\*(C`ev_idle\*(C'\fR watchers, which provide this functionality. |
1572 | you need to look at \f(CW\*(C`ev_idle\*(C'\fR watchers, which provide this functionality. |
1389 | .Sp |
1573 | .Sp |
1390 | You \fImust not\fR change the priority of a watcher as long as it is active or |
1574 | You \fImust not\fR change the priority of a watcher as long as it is active |
1391 | pending. |
1575 | or pending. Reading the priority with \f(CW\*(C`ev_priority\*(C'\fR is fine in any state. |
1392 | .Sp |
1576 | .Sp |
1393 | Setting a priority outside the range of \f(CW\*(C`EV_MINPRI\*(C'\fR to \f(CW\*(C`EV_MAXPRI\*(C'\fR is |
1577 | Setting a priority outside the range of \f(CW\*(C`EV_MINPRI\*(C'\fR to \f(CW\*(C`EV_MAXPRI\*(C'\fR is |
1394 | fine, as long as you do not mind that the priority value you query might |
1578 | fine, as long as you do not mind that the priority value you query might |
1395 | or might not have been clamped to the valid range. |
1579 | or might not have been clamped to the valid range. |
1396 | .Sp |
1580 | .Sp |
1397 | The default priority used by watchers when no priority has been set is |
1581 | The default priority used by watchers when no priority has been set is |
1398 | always \f(CW0\fR, which is supposed to not be too high and not be too low :). |
1582 | always \f(CW0\fR, which is supposed to not be too high and not be too low :). |
1399 | .Sp |
1583 | .Sp |
1400 | See \*(L"\s-1WATCHER\s0 \s-1PRIORITY\s0 \s-1MODELS\s0\*(R", below, for a more thorough treatment of |
1584 | See \*(L"\s-1WATCHER PRIORITY MODELS\*(R"\s0, below, for a more thorough treatment of |
1401 | priorities. |
1585 | priorities. |
1402 | .IP "ev_invoke (loop, ev_TYPE *watcher, int revents)" 4 |
1586 | .IP "ev_invoke (loop, ev_TYPE *watcher, int revents)" 4 |
1403 | .IX Item "ev_invoke (loop, ev_TYPE *watcher, int revents)" |
1587 | .IX Item "ev_invoke (loop, ev_TYPE *watcher, int revents)" |
1404 | 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 |
1588 | 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 |
1405 | \&\f(CW\*(C`loop\*(C'\fR nor \f(CW\*(C`revents\*(C'\fR need to be valid as long as the watcher callback |
1589 | \&\f(CW\*(C`loop\*(C'\fR nor \f(CW\*(C`revents\*(C'\fR need to be valid as long as the watcher callback |
… | |
… | |
1415 | callback to be invoked, which can be accomplished with this function. |
1599 | callback to be invoked, which can be accomplished with this function. |
1416 | .IP "ev_feed_event (loop, ev_TYPE *watcher, int revents)" 4 |
1600 | .IP "ev_feed_event (loop, ev_TYPE *watcher, int revents)" 4 |
1417 | .IX Item "ev_feed_event (loop, ev_TYPE *watcher, int revents)" |
1601 | .IX Item "ev_feed_event (loop, ev_TYPE *watcher, int revents)" |
1418 | Feeds the given event set into the event loop, as if the specified event |
1602 | Feeds the given event set into the event loop, as if the specified event |
1419 | had happened for the specified watcher (which must be a pointer to an |
1603 | had happened for the specified watcher (which must be a pointer to an |
1420 | initialised but not necessarily started event watcher). Obviously you must |
1604 | initialised but not necessarily started event watcher, though it can be |
1421 | not free the watcher as long as it has pending events. |
1605 | active). Obviously you must not free the watcher as long as it has pending |
|
|
1606 | events. |
1422 | .Sp |
1607 | .Sp |
1423 | Stopping the watcher, letting libev invoke it, or calling |
1608 | Stopping the watcher, letting libev invoke it, or calling |
1424 | \&\f(CW\*(C`ev_clear_pending\*(C'\fR will clear the pending event, even if the watcher was |
1609 | \&\f(CW\*(C`ev_clear_pending\*(C'\fR will clear the pending event, even if the watcher was |
1425 | not started in the first place. |
1610 | not started in the first place. |
1426 | .Sp |
1611 | .Sp |
1427 | See also \f(CW\*(C`ev_feed_fd_event\*(C'\fR and \f(CW\*(C`ev_feed_signal_event\*(C'\fR for related |
1612 | See also \f(CW\*(C`ev_feed_fd_event\*(C'\fR and \f(CW\*(C`ev_feed_signal_event\*(C'\fR for related |
1428 | functions that do not need a watcher. |
1613 | functions that do not need a watcher. |
1429 | .SS "\s-1ASSOCIATING\s0 \s-1CUSTOM\s0 \s-1DATA\s0 \s-1WITH\s0 A \s-1WATCHER\s0" |
|
|
1430 | .IX Subsection "ASSOCIATING CUSTOM DATA WITH A WATCHER" |
|
|
1431 | Each watcher has, by default, a member \f(CW\*(C`void *data\*(C'\fR that you can change |
|
|
1432 | and read at any time: libev will completely ignore it. This can be used |
|
|
1433 | to associate arbitrary data with your watcher. If you need more data and |
|
|
1434 | don't want to allocate memory and store a pointer to it in that data |
|
|
1435 | member, you can also \*(L"subclass\*(R" the watcher type and provide your own |
|
|
1436 | data: |
|
|
1437 | .PP |
1614 | .PP |
1438 | .Vb 7 |
1615 | See also the \*(L"\s-1ASSOCIATING CUSTOM DATA WITH A WATCHER\*(R"\s0 and \*(L"\s-1BUILDING YOUR |
1439 | \& struct my_io |
1616 | OWN COMPOSITE WATCHERS\*(R"\s0 idioms. |
1440 | \& { |
|
|
1441 | \& ev_io io; |
|
|
1442 | \& int otherfd; |
|
|
1443 | \& void *somedata; |
|
|
1444 | \& struct whatever *mostinteresting; |
|
|
1445 | \& }; |
|
|
1446 | \& |
|
|
1447 | \& ... |
|
|
1448 | \& struct my_io w; |
|
|
1449 | \& ev_io_init (&w.io, my_cb, fd, EV_READ); |
|
|
1450 | .Ve |
|
|
1451 | .PP |
|
|
1452 | And since your callback will be called with a pointer to the watcher, you |
|
|
1453 | can cast it back to your own type: |
|
|
1454 | .PP |
|
|
1455 | .Vb 5 |
|
|
1456 | \& static void my_cb (struct ev_loop *loop, ev_io *w_, int revents) |
|
|
1457 | \& { |
|
|
1458 | \& struct my_io *w = (struct my_io *)w_; |
|
|
1459 | \& ... |
|
|
1460 | \& } |
|
|
1461 | .Ve |
|
|
1462 | .PP |
|
|
1463 | More interesting and less C\-conformant ways of casting your callback type |
|
|
1464 | instead have been omitted. |
|
|
1465 | .PP |
|
|
1466 | Another common scenario is to use some data structure with multiple |
|
|
1467 | embedded watchers: |
|
|
1468 | .PP |
|
|
1469 | .Vb 6 |
|
|
1470 | \& struct my_biggy |
|
|
1471 | \& { |
|
|
1472 | \& int some_data; |
|
|
1473 | \& ev_timer t1; |
|
|
1474 | \& ev_timer t2; |
|
|
1475 | \& } |
|
|
1476 | .Ve |
|
|
1477 | .PP |
|
|
1478 | In this case getting the pointer to \f(CW\*(C`my_biggy\*(C'\fR is a bit more |
|
|
1479 | complicated: Either you store the address of your \f(CW\*(C`my_biggy\*(C'\fR struct |
|
|
1480 | in the \f(CW\*(C`data\*(C'\fR member of the watcher (for woozies), or you need to use |
|
|
1481 | some pointer arithmetic using \f(CW\*(C`offsetof\*(C'\fR inside your watchers (for real |
|
|
1482 | programmers): |
|
|
1483 | .PP |
|
|
1484 | .Vb 1 |
|
|
1485 | \& #include <stddef.h> |
|
|
1486 | \& |
|
|
1487 | \& static void |
|
|
1488 | \& t1_cb (EV_P_ ev_timer *w, int revents) |
|
|
1489 | \& { |
|
|
1490 | \& struct my_biggy big = (struct my_biggy *) |
|
|
1491 | \& (((char *)w) \- offsetof (struct my_biggy, t1)); |
|
|
1492 | \& } |
|
|
1493 | \& |
|
|
1494 | \& static void |
|
|
1495 | \& t2_cb (EV_P_ ev_timer *w, int revents) |
|
|
1496 | \& { |
|
|
1497 | \& struct my_biggy big = (struct my_biggy *) |
|
|
1498 | \& (((char *)w) \- offsetof (struct my_biggy, t2)); |
|
|
1499 | \& } |
|
|
1500 | .Ve |
|
|
1501 | .SS "\s-1WATCHER\s0 \s-1STATES\s0" |
1617 | .SS "\s-1WATCHER STATES\s0" |
1502 | .IX Subsection "WATCHER STATES" |
1618 | .IX Subsection "WATCHER STATES" |
1503 | There are various watcher states mentioned throughout this manual \- |
1619 | There are various watcher states mentioned throughout this manual \- |
1504 | active, pending and so on. In this section these states and the rules to |
1620 | active, pending and so on. In this section these states and the rules to |
1505 | transition between them will be described in more detail \- and while these |
1621 | transition between them will be described in more detail \- and while these |
1506 | rules might look complicated, they usually do \*(L"the right thing\*(R". |
1622 | rules might look complicated, they usually do \*(L"the right thing\*(R". |
1507 | .IP "initialiased" 4 |
1623 | .IP "initialised" 4 |
1508 | .IX Item "initialiased" |
1624 | .IX Item "initialised" |
1509 | Before a watcher can be registered with the event looop it has to be |
1625 | Before a watcher can be registered with the event loop it has to be |
1510 | initialised. This can be done with a call to \f(CW\*(C`ev_TYPE_init\*(C'\fR, or calls to |
1626 | initialised. This can be done with a call to \f(CW\*(C`ev_TYPE_init\*(C'\fR, or calls to |
1511 | \&\f(CW\*(C`ev_init\*(C'\fR followed by the watcher-specific \f(CW\*(C`ev_TYPE_set\*(C'\fR function. |
1627 | \&\f(CW\*(C`ev_init\*(C'\fR followed by the watcher-specific \f(CW\*(C`ev_TYPE_set\*(C'\fR function. |
1512 | .Sp |
1628 | .Sp |
1513 | In this state it is simply some block of memory that is suitable for use |
1629 | In this state it is simply some block of memory that is suitable for |
1514 | in an event loop. It can be moved around, freed, reused etc. at will. |
1630 | use in an event loop. It can be moved around, freed, reused etc. at |
|
|
1631 | will \- as long as you either keep the memory contents intact, or call |
|
|
1632 | \&\f(CW\*(C`ev_TYPE_init\*(C'\fR again. |
1515 | .IP "started/running/active" 4 |
1633 | .IP "started/running/active" 4 |
1516 | .IX Item "started/running/active" |
1634 | .IX Item "started/running/active" |
1517 | Once a watcher has been started with a call to \f(CW\*(C`ev_TYPE_start\*(C'\fR it becomes |
1635 | Once a watcher has been started with a call to \f(CW\*(C`ev_TYPE_start\*(C'\fR it becomes |
1518 | property of the event loop, and is actively waiting for events. While in |
1636 | property of the event loop, and is actively waiting for events. While in |
1519 | this state it cannot be accessed (except in a few documented ways), moved, |
1637 | this state it cannot be accessed (except in a few documented ways, such as |
1520 | freed or anything else \- the only legal thing is to keep a pointer to it, |
1638 | stoping it), moved, freed or anything else \- the only legal thing is to |
1521 | and call libev functions on it that are documented to work on active watchers. |
1639 | keep a pointer to it, and call libev functions on it that are documented |
|
|
1640 | to work on active watchers. |
|
|
1641 | .Sp |
|
|
1642 | As a rule of thumb, before accessing a member or calling any function on |
|
|
1643 | a watcher, it should be stopped (or freshly initialised). If that is not |
|
|
1644 | convenient, you can check the documentation for that function or member to |
|
|
1645 | see if it is safe to use on an active watcher. |
1522 | .IP "pending" 4 |
1646 | .IP "pending" 4 |
1523 | .IX Item "pending" |
1647 | .IX Item "pending" |
1524 | If a watcher is active and libev determines that an event it is interested |
1648 | If a watcher is active and libev determines that an event it is interested |
1525 | in has occurred (such as a timer expiring), it will become pending. It will |
1649 | in has occurred (such as a timer expiring), it will become pending. It |
1526 | stay in this pending state until either it is stopped or its callback is |
1650 | will stay in this pending state until either it is explicitly stopped or |
1527 | about to be invoked, so it is not normally pending inside the watcher |
1651 | its callback is about to be invoked, so it is not normally pending inside |
1528 | callback. |
1652 | the watcher callback. |
1529 | .Sp |
1653 | .Sp |
1530 | The watcher might or might not be active while it is pending (for example, |
1654 | Generally, the watcher might or might not be active while it is pending |
1531 | an expired non-repeating timer can be pending but no longer active). If it |
1655 | (for example, an expired non-repeating timer can be pending but no longer |
1532 | is stopped, it can be freely accessed (e.g. by calling \f(CW\*(C`ev_TYPE_set\*(C'\fR), |
1656 | active). If it is pending but not active, it can be freely accessed (e.g. |
1533 | but it is still property of the event loop at this time, so cannot be |
1657 | by calling \f(CW\*(C`ev_TYPE_set\*(C'\fR), but it is still property of the event loop at |
1534 | moved, freed or reused. And if it is active the rules described in the |
1658 | this time, so cannot be moved, freed or reused. And if it is active the |
1535 | previous item still apply. |
1659 | rules described in the previous item still apply. |
|
|
1660 | .Sp |
|
|
1661 | Explicitly stopping a watcher will also clear the pending state |
|
|
1662 | unconditionally, so it is safe to stop a watcher and then free it. |
1536 | .Sp |
1663 | .Sp |
1537 | It is also possible to feed an event on a watcher that is not active (e.g. |
1664 | It is also possible to feed an event on a watcher that is not active (e.g. |
1538 | via \f(CW\*(C`ev_feed_event\*(C'\fR), in which case it becomes pending without being |
1665 | via \f(CW\*(C`ev_feed_event\*(C'\fR), in which case it becomes pending without being |
1539 | active. |
1666 | active. |
1540 | .IP "stopped" 4 |
1667 | .IP "stopped" 4 |
… | |
… | |
1544 | latter will clear any pending state the watcher might be in, regardless |
1671 | latter will clear any pending state the watcher might be in, regardless |
1545 | of whether it was active or not, so stopping a watcher explicitly before |
1672 | of whether it was active or not, so stopping a watcher explicitly before |
1546 | freeing it is often a good idea. |
1673 | freeing it is often a good idea. |
1547 | .Sp |
1674 | .Sp |
1548 | While stopped (and not pending) the watcher is essentially in the |
1675 | While stopped (and not pending) the watcher is essentially in the |
1549 | initialised state, that is it can be reused, moved, modified in any way |
1676 | initialised state, that is, it can be reused, moved, modified in any way |
1550 | you wish. |
1677 | you wish (but when you trash the memory block, you need to \f(CW\*(C`ev_TYPE_init\*(C'\fR |
|
|
1678 | it again). |
1551 | .SS "\s-1WATCHER\s0 \s-1PRIORITY\s0 \s-1MODELS\s0" |
1679 | .SS "\s-1WATCHER PRIORITY MODELS\s0" |
1552 | .IX Subsection "WATCHER PRIORITY MODELS" |
1680 | .IX Subsection "WATCHER PRIORITY MODELS" |
1553 | Many event loops support \fIwatcher priorities\fR, which are usually small |
1681 | Many event loops support \fIwatcher priorities\fR, which are usually small |
1554 | integers that influence the ordering of event callback invocation |
1682 | integers that influence the ordering of event callback invocation |
1555 | between watchers in some way, all else being equal. |
1683 | between watchers in some way, all else being equal. |
1556 | .PP |
1684 | .PP |
1557 | In libev, Watcher priorities can be set using \f(CW\*(C`ev_set_priority\*(C'\fR. See its |
1685 | In libev, watcher priorities can be set using \f(CW\*(C`ev_set_priority\*(C'\fR. See its |
1558 | description for the more technical details such as the actual priority |
1686 | description for the more technical details such as the actual priority |
1559 | range. |
1687 | range. |
1560 | .PP |
1688 | .PP |
1561 | There are two common ways how these these priorities are being interpreted |
1689 | There are two common ways how these these priorities are being interpreted |
1562 | by event loops: |
1690 | by event loops: |
… | |
… | |
1656 | .IX Header "WATCHER TYPES" |
1784 | .IX Header "WATCHER TYPES" |
1657 | This section describes each watcher in detail, but will not repeat |
1785 | This section describes each watcher in detail, but will not repeat |
1658 | information given in the last section. Any initialisation/set macros, |
1786 | information given in the last section. Any initialisation/set macros, |
1659 | functions and members specific to the watcher type are explained. |
1787 | functions and members specific to the watcher type are explained. |
1660 | .PP |
1788 | .PP |
1661 | Members are additionally marked with either \fI[read\-only]\fR, meaning that, |
1789 | Most members are additionally marked with either \fI[read\-only]\fR, meaning |
1662 | while the watcher is active, you can look at the member and expect some |
1790 | that, while the watcher is active, you can look at the member and expect |
1663 | sensible content, but you must not modify it (you can modify it while the |
1791 | some sensible content, but you must not modify it (you can modify it while |
1664 | watcher is stopped to your hearts content), or \fI[read\-write]\fR, which |
1792 | the watcher is stopped to your hearts content), or \fI[read\-write]\fR, which |
1665 | means you can expect it to have some sensible content while the watcher |
1793 | means you can expect it to have some sensible content while the watcher is |
1666 | is active, but you can also modify it. Modifying it may not do something |
1794 | active, but you can also modify it (within the same thread as the event |
|
|
1795 | loop, i.e. without creating data races). Modifying it may not do something |
1667 | sensible or take immediate effect (or do anything at all), but libev will |
1796 | sensible or take immediate effect (or do anything at all), but libev will |
1668 | not crash or malfunction in any way. |
1797 | not crash or malfunction in any way. |
|
|
1798 | .PP |
|
|
1799 | In any case, the documentation for each member will explain what the |
|
|
1800 | effects are, and if there are any additional access restrictions. |
1669 | .ie n .SS """ev_io"" \- is this file descriptor readable or writable?" |
1801 | .ie n .SS """ev_io"" \- is this file descriptor readable or writable?" |
1670 | .el .SS "\f(CWev_io\fP \- is this file descriptor readable or writable?" |
1802 | .el .SS "\f(CWev_io\fP \- is this file descriptor readable or writable?" |
1671 | .IX Subsection "ev_io - is this file descriptor readable or writable?" |
1803 | .IX Subsection "ev_io - is this file descriptor readable or writable?" |
1672 | I/O watchers check whether a file descriptor is readable or writable |
1804 | I/O watchers check whether a file descriptor is readable or writable |
1673 | in each iteration of the event loop, or, more precisely, when reading |
1805 | in each iteration of the event loop, or, more precisely, when reading |
… | |
… | |
1680 | In general you can register as many read and/or write event watchers per |
1812 | In general you can register as many read and/or write event watchers per |
1681 | fd as you want (as long as you don't confuse yourself). Setting all file |
1813 | fd as you want (as long as you don't confuse yourself). Setting all file |
1682 | descriptors to non-blocking mode is also usually a good idea (but not |
1814 | descriptors to non-blocking mode is also usually a good idea (but not |
1683 | required if you know what you are doing). |
1815 | required if you know what you are doing). |
1684 | .PP |
1816 | .PP |
1685 | If you cannot use non-blocking mode, then force the use of a |
|
|
1686 | known-to-be-good backend (at the time of this writing, this includes only |
|
|
1687 | \&\f(CW\*(C`EVBACKEND_SELECT\*(C'\fR and \f(CW\*(C`EVBACKEND_POLL\*(C'\fR). The same applies to file |
|
|
1688 | descriptors for which non-blocking operation makes no sense (such as |
|
|
1689 | files) \- libev doesn't guarantee any specific behaviour in that case. |
|
|
1690 | .PP |
|
|
1691 | Another thing you have to watch out for is that it is quite easy to |
1817 | Another thing you have to watch out for is that it is quite easy to |
1692 | receive \*(L"spurious\*(R" readiness notifications, that is your callback might |
1818 | receive \*(L"spurious\*(R" readiness notifications, that is, your callback might |
1693 | be called with \f(CW\*(C`EV_READ\*(C'\fR but a subsequent \f(CW\*(C`read\*(C'\fR(2) will actually block |
1819 | be called with \f(CW\*(C`EV_READ\*(C'\fR but a subsequent \f(CW\*(C`read\*(C'\fR(2) will actually block |
1694 | because there is no data. Not only are some backends known to create a |
1820 | because there is no data. It is very easy to get into this situation even |
1695 | lot of those (for example Solaris ports), it is very easy to get into |
1821 | with a relatively standard program structure. Thus it is best to always |
1696 | this situation even with a relatively standard program structure. Thus |
1822 | use non-blocking I/O: An extra \f(CW\*(C`read\*(C'\fR(2) returning \f(CW\*(C`EAGAIN\*(C'\fR is far |
1697 | it is best to always use non-blocking I/O: An extra \f(CW\*(C`read\*(C'\fR(2) returning |
|
|
1698 | \&\f(CW\*(C`EAGAIN\*(C'\fR is far preferable to a program hanging until some data arrives. |
1823 | preferable to a program hanging until some data arrives. |
1699 | .PP |
1824 | .PP |
1700 | If you cannot run the fd in non-blocking mode (for example you should |
1825 | If you cannot run the fd in non-blocking mode (for example you should |
1701 | not play around with an Xlib connection), then you have to separately |
1826 | not play around with an Xlib connection), then you have to separately |
1702 | re-test whether a file descriptor is really ready with a known-to-be good |
1827 | re-test whether a file descriptor is really ready with a known-to-be good |
1703 | interface such as poll (fortunately in our Xlib example, Xlib already |
1828 | interface such as poll (fortunately in the case of Xlib, it already does |
1704 | does this on its own, so its quite safe to use). Some people additionally |
1829 | this on its own, so its quite safe to use). Some people additionally |
1705 | use \f(CW\*(C`SIGALRM\*(C'\fR and an interval timer, just to be sure you won't block |
1830 | use \f(CW\*(C`SIGALRM\*(C'\fR and an interval timer, just to be sure you won't block |
1706 | indefinitely. |
1831 | indefinitely. |
1707 | .PP |
1832 | .PP |
1708 | But really, best use non-blocking mode. |
1833 | But really, best use non-blocking mode. |
1709 | .PP |
1834 | .PP |
1710 | \fIThe special problem of disappearing file descriptors\fR |
1835 | \fIThe special problem of disappearing file descriptors\fR |
1711 | .IX Subsection "The special problem of disappearing file descriptors" |
1836 | .IX Subsection "The special problem of disappearing file descriptors" |
1712 | .PP |
1837 | .PP |
1713 | Some backends (e.g. kqueue, epoll) need to be told about closing a file |
1838 | Some backends (e.g. kqueue, epoll, linuxaio) need to be told about closing |
1714 | descriptor (either due to calling \f(CW\*(C`close\*(C'\fR explicitly or any other means, |
1839 | a file descriptor (either due to calling \f(CW\*(C`close\*(C'\fR explicitly or any other |
1715 | such as \f(CW\*(C`dup2\*(C'\fR). The reason is that you register interest in some file |
1840 | means, such as \f(CW\*(C`dup2\*(C'\fR). The reason is that you register interest in some |
1716 | descriptor, but when it goes away, the operating system will silently drop |
1841 | file descriptor, but when it goes away, the operating system will silently |
1717 | this interest. If another file descriptor with the same number then is |
1842 | drop this interest. If another file descriptor with the same number then |
1718 | registered with libev, there is no efficient way to see that this is, in |
1843 | is registered with libev, there is no efficient way to see that this is, |
1719 | fact, a different file descriptor. |
1844 | in fact, a different file descriptor. |
1720 | .PP |
1845 | .PP |
1721 | To avoid having to explicitly tell libev about such cases, libev follows |
1846 | To avoid having to explicitly tell libev about such cases, libev follows |
1722 | the following policy: Each time \f(CW\*(C`ev_io_set\*(C'\fR is being called, libev |
1847 | the following policy: Each time \f(CW\*(C`ev_io_set\*(C'\fR is being called, libev |
1723 | will assume that this is potentially a new file descriptor, otherwise |
1848 | will assume that this is potentially a new file descriptor, otherwise |
1724 | it is assumed that the file descriptor stays the same. That means that |
1849 | it is assumed that the file descriptor stays the same. That means that |
… | |
… | |
1739 | .PP |
1864 | .PP |
1740 | There is no workaround possible except not registering events |
1865 | There is no workaround possible except not registering events |
1741 | for potentially \f(CW\*(C`dup ()\*(C'\fR'ed file descriptors, or to resort to |
1866 | for potentially \f(CW\*(C`dup ()\*(C'\fR'ed file descriptors, or to resort to |
1742 | \&\f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or \f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
1867 | \&\f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or \f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
1743 | .PP |
1868 | .PP |
|
|
1869 | \fIThe special problem of files\fR |
|
|
1870 | .IX Subsection "The special problem of files" |
|
|
1871 | .PP |
|
|
1872 | Many people try to use \f(CW\*(C`select\*(C'\fR (or libev) on file descriptors |
|
|
1873 | representing files, and expect it to become ready when their program |
|
|
1874 | doesn't block on disk accesses (which can take a long time on their own). |
|
|
1875 | .PP |
|
|
1876 | However, this cannot ever work in the \*(L"expected\*(R" way \- you get a readiness |
|
|
1877 | notification as soon as the kernel knows whether and how much data is |
|
|
1878 | there, and in the case of open files, that's always the case, so you |
|
|
1879 | always get a readiness notification instantly, and your read (or possibly |
|
|
1880 | write) will still block on the disk I/O. |
|
|
1881 | .PP |
|
|
1882 | Another way to view it is that in the case of sockets, pipes, character |
|
|
1883 | devices and so on, there is another party (the sender) that delivers data |
|
|
1884 | on its own, but in the case of files, there is no such thing: the disk |
|
|
1885 | will not send data on its own, simply because it doesn't know what you |
|
|
1886 | wish to read \- you would first have to request some data. |
|
|
1887 | .PP |
|
|
1888 | Since files are typically not-so-well supported by advanced notification |
|
|
1889 | mechanism, libev tries hard to emulate \s-1POSIX\s0 behaviour with respect |
|
|
1890 | to files, even though you should not use it. The reason for this is |
|
|
1891 | convenience: sometimes you want to watch \s-1STDIN\s0 or \s-1STDOUT,\s0 which is |
|
|
1892 | usually a tty, often a pipe, but also sometimes files or special devices |
|
|
1893 | (for example, \f(CW\*(C`epoll\*(C'\fR on Linux works with \fI/dev/random\fR but not with |
|
|
1894 | \&\fI/dev/urandom\fR), and even though the file might better be served with |
|
|
1895 | asynchronous I/O instead of with non-blocking I/O, it is still useful when |
|
|
1896 | it \*(L"just works\*(R" instead of freezing. |
|
|
1897 | .PP |
|
|
1898 | So avoid file descriptors pointing to files when you know it (e.g. use |
|
|
1899 | libeio), but use them when it is convenient, e.g. for \s-1STDIN/STDOUT,\s0 or |
|
|
1900 | when you rarely read from a file instead of from a socket, and want to |
|
|
1901 | reuse the same code path. |
|
|
1902 | .PP |
1744 | \fIThe special problem of fork\fR |
1903 | \fIThe special problem of fork\fR |
1745 | .IX Subsection "The special problem of fork" |
1904 | .IX Subsection "The special problem of fork" |
1746 | .PP |
1905 | .PP |
1747 | Some backends (epoll, kqueue) do not support \f(CW\*(C`fork ()\*(C'\fR at all or exhibit |
1906 | Some backends (epoll, kqueue, linuxaio, iouring) do not support \f(CW\*(C`fork ()\*(C'\fR |
1748 | useless behaviour. Libev fully supports fork, but needs to be told about |
1907 | at all or exhibit useless behaviour. Libev fully supports fork, but needs |
1749 | it in the child. |
1908 | to be told about it in the child if you want to continue to use it in the |
|
|
1909 | child. |
1750 | .PP |
1910 | .PP |
1751 | To support fork in your programs, you either have to call |
1911 | To support fork in your child processes, you have to call \f(CW\*(C`ev_loop_fork |
1752 | \&\f(CW\*(C`ev_default_fork ()\*(C'\fR or \f(CW\*(C`ev_loop_fork ()\*(C'\fR after a fork in the child, |
1912 | ()\*(C'\fR after a fork in the child, enable \f(CW\*(C`EVFLAG_FORKCHECK\*(C'\fR, or resort to |
1753 | enable \f(CW\*(C`EVFLAG_FORKCHECK\*(C'\fR, or resort to \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or |
1913 | \&\f(CW\*(C`EVBACKEND_SELECT\*(C'\fR or \f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
1754 | \&\f(CW\*(C`EVBACKEND_POLL\*(C'\fR. |
|
|
1755 | .PP |
1914 | .PP |
1756 | \fIThe special problem of \s-1SIGPIPE\s0\fR |
1915 | \fIThe special problem of \s-1SIGPIPE\s0\fR |
1757 | .IX Subsection "The special problem of SIGPIPE" |
1916 | .IX Subsection "The special problem of SIGPIPE" |
1758 | .PP |
1917 | .PP |
1759 | While not really specific to libev, it is easy to forget about \f(CW\*(C`SIGPIPE\*(C'\fR: |
1918 | While not really specific to libev, it is easy to forget about \f(CW\*(C`SIGPIPE\*(C'\fR: |
1760 | when writing to a pipe whose other end has been closed, your program gets |
1919 | when writing to a pipe whose other end has been closed, your program gets |
1761 | sent a \s-1SIGPIPE\s0, which, by default, aborts your program. For most programs |
1920 | sent a \s-1SIGPIPE,\s0 which, by default, aborts your program. For most programs |
1762 | this is sensible behaviour, for daemons, this is usually undesirable. |
1921 | this is sensible behaviour, for daemons, this is usually undesirable. |
1763 | .PP |
1922 | .PP |
1764 | So when you encounter spurious, unexplained daemon exits, make sure you |
1923 | So when you encounter spurious, unexplained daemon exits, make sure you |
1765 | ignore \s-1SIGPIPE\s0 (and maybe make sure you log the exit status of your daemon |
1924 | ignore \s-1SIGPIPE\s0 (and maybe make sure you log the exit status of your daemon |
1766 | somewhere, as that would have given you a big clue). |
1925 | somewhere, as that would have given you a big clue). |
1767 | .PP |
1926 | .PP |
1768 | \fIThe special problem of \fIaccept()\fIing when you can't\fR |
1927 | \fIThe special problem of \f(BIaccept()\fIing when you can't\fR |
1769 | .IX Subsection "The special problem of accept()ing when you can't" |
1928 | .IX Subsection "The special problem of accept()ing when you can't" |
1770 | .PP |
1929 | .PP |
1771 | Many implementations of the \s-1POSIX\s0 \f(CW\*(C`accept\*(C'\fR function (for example, |
1930 | Many implementations of the \s-1POSIX\s0 \f(CW\*(C`accept\*(C'\fR function (for example, |
1772 | found in post\-2004 Linux) have the peculiar behaviour of not removing a |
1931 | found in post\-2004 Linux) have the peculiar behaviour of not removing a |
1773 | connection from the pending queue in all error cases. |
1932 | connection from the pending queue in all error cases. |
… | |
… | |
1812 | .PD 0 |
1971 | .PD 0 |
1813 | .IP "ev_io_set (ev_io *, int fd, int events)" 4 |
1972 | .IP "ev_io_set (ev_io *, int fd, int events)" 4 |
1814 | .IX Item "ev_io_set (ev_io *, int fd, int events)" |
1973 | .IX Item "ev_io_set (ev_io *, int fd, int events)" |
1815 | .PD |
1974 | .PD |
1816 | Configures an \f(CW\*(C`ev_io\*(C'\fR watcher. The \f(CW\*(C`fd\*(C'\fR is the file descriptor to |
1975 | Configures an \f(CW\*(C`ev_io\*(C'\fR watcher. The \f(CW\*(C`fd\*(C'\fR is the file descriptor to |
1817 | receive events for and \f(CW\*(C`events\*(C'\fR is either \f(CW\*(C`EV_READ\*(C'\fR, \f(CW\*(C`EV_WRITE\*(C'\fR or |
1976 | receive events for and \f(CW\*(C`events\*(C'\fR is either \f(CW\*(C`EV_READ\*(C'\fR, \f(CW\*(C`EV_WRITE\*(C'\fR, both |
1818 | \&\f(CW\*(C`EV_READ | EV_WRITE\*(C'\fR, to express the desire to receive the given events. |
1977 | \&\f(CW\*(C`EV_READ | EV_WRITE\*(C'\fR or \f(CW0\fR, to express the desire to receive the given |
|
|
1978 | events. |
|
|
1979 | .Sp |
|
|
1980 | Note that setting the \f(CW\*(C`events\*(C'\fR to \f(CW0\fR and starting the watcher is |
|
|
1981 | supported, but not specially optimized \- if your program sometimes happens |
|
|
1982 | to generate this combination this is fine, but if it is easy to avoid |
|
|
1983 | starting an io watcher watching for no events you should do so. |
|
|
1984 | .IP "ev_io_modify (ev_io *, int events)" 4 |
|
|
1985 | .IX Item "ev_io_modify (ev_io *, int events)" |
|
|
1986 | Similar to \f(CW\*(C`ev_io_set\*(C'\fR, but only changes the requested events. Using this |
|
|
1987 | might be faster with some backends, as libev can assume that the \f(CW\*(C`fd\*(C'\fR |
|
|
1988 | still refers to the same underlying file description, something it cannot |
|
|
1989 | do when using \f(CW\*(C`ev_io_set\*(C'\fR. |
1819 | .IP "int fd [read\-only]" 4 |
1990 | .IP "int fd [no\-modify]" 4 |
1820 | .IX Item "int fd [read-only]" |
1991 | .IX Item "int fd [no-modify]" |
1821 | The file descriptor being watched. |
1992 | The file descriptor being watched. While it can be read at any time, you |
|
|
1993 | must not modify this member even when the watcher is stopped \- always use |
|
|
1994 | \&\f(CW\*(C`ev_io_set\*(C'\fR for that. |
1822 | .IP "int events [read\-only]" 4 |
1995 | .IP "int events [no\-modify]" 4 |
1823 | .IX Item "int events [read-only]" |
1996 | .IX Item "int events [no-modify]" |
1824 | The events being watched. |
1997 | The set of events the fd is being watched for, among other flags. Remember |
|
|
1998 | that this is a bit set \- to test for \f(CW\*(C`EV_READ\*(C'\fR, use \f(CW\*(C`w\->events & |
|
|
1999 | EV_READ\*(C'\fR, and similarly for \f(CW\*(C`EV_WRITE\*(C'\fR. |
|
|
2000 | .Sp |
|
|
2001 | As with \f(CW\*(C`fd\*(C'\fR, you must not modify this member even when the watcher is |
|
|
2002 | stopped, always use \f(CW\*(C`ev_io_set\*(C'\fR or \f(CW\*(C`ev_io_modify\*(C'\fR for that. |
1825 | .PP |
2003 | .PP |
1826 | \fIExamples\fR |
2004 | \fIExamples\fR |
1827 | .IX Subsection "Examples" |
2005 | .IX Subsection "Examples" |
1828 | .PP |
2006 | .PP |
1829 | Example: Call \f(CW\*(C`stdin_readable_cb\*(C'\fR when \s-1STDIN_FILENO\s0 has become, well |
2007 | Example: Call \f(CW\*(C`stdin_readable_cb\*(C'\fR when \s-1STDIN_FILENO\s0 has become, well |
… | |
… | |
1857 | detecting time jumps is hard, and some inaccuracies are unavoidable (the |
2035 | detecting time jumps is hard, and some inaccuracies are unavoidable (the |
1858 | monotonic clock option helps a lot here). |
2036 | monotonic clock option helps a lot here). |
1859 | .PP |
2037 | .PP |
1860 | The callback is guaranteed to be invoked only \fIafter\fR its timeout has |
2038 | The callback is guaranteed to be invoked only \fIafter\fR its timeout has |
1861 | passed (not \fIat\fR, so on systems with very low-resolution clocks this |
2039 | passed (not \fIat\fR, so on systems with very low-resolution clocks this |
1862 | might introduce a small delay). If multiple timers become ready during the |
2040 | might introduce a small delay, see \*(L"the special problem of being too |
|
|
2041 | early\*(R", below). If multiple timers become ready during the same loop |
1863 | same loop iteration then the ones with earlier time-out values are invoked |
2042 | iteration then the ones with earlier time-out values are invoked before |
1864 | before ones of the same priority with later time-out values (but this is |
2043 | ones of the same priority with later time-out values (but this is no |
1865 | no longer true when a callback calls \f(CW\*(C`ev_run\*(C'\fR recursively). |
2044 | longer true when a callback calls \f(CW\*(C`ev_run\*(C'\fR recursively). |
1866 | .PP |
2045 | .PP |
1867 | \fIBe smart about timeouts\fR |
2046 | \fIBe smart about timeouts\fR |
1868 | .IX Subsection "Be smart about timeouts" |
2047 | .IX Subsection "Be smart about timeouts" |
1869 | .PP |
2048 | .PP |
1870 | Many real-world problems involve some kind of timeout, usually for error |
2049 | Many real-world problems involve some kind of timeout, usually for error |
… | |
… | |
1952 | .Sp |
2131 | .Sp |
1953 | In this case, it would be more efficient to leave the \f(CW\*(C`ev_timer\*(C'\fR alone, |
2132 | In this case, it would be more efficient to leave the \f(CW\*(C`ev_timer\*(C'\fR alone, |
1954 | but remember the time of last activity, and check for a real timeout only |
2133 | but remember the time of last activity, and check for a real timeout only |
1955 | within the callback: |
2134 | within the callback: |
1956 | .Sp |
2135 | .Sp |
1957 | .Vb 1 |
2136 | .Vb 3 |
|
|
2137 | \& ev_tstamp timeout = 60.; |
1958 | \& ev_tstamp last_activity; // time of last activity |
2138 | \& ev_tstamp last_activity; // time of last activity |
|
|
2139 | \& ev_timer timer; |
1959 | \& |
2140 | \& |
1960 | \& static void |
2141 | \& static void |
1961 | \& callback (EV_P_ ev_timer *w, int revents) |
2142 | \& callback (EV_P_ ev_timer *w, int revents) |
1962 | \& { |
2143 | \& { |
1963 | \& ev_tstamp now = ev_now (EV_A); |
2144 | \& // calculate when the timeout would happen |
1964 | \& ev_tstamp timeout = last_activity + 60.; |
2145 | \& ev_tstamp after = last_activity \- ev_now (EV_A) + timeout; |
1965 | \& |
2146 | \& |
1966 | \& // if last_activity + 60. is older than now, we did time out |
2147 | \& // if negative, it means we the timeout already occurred |
1967 | \& if (timeout < now) |
2148 | \& if (after < 0.) |
1968 | \& { |
2149 | \& { |
1969 | \& // timeout occurred, take action |
2150 | \& // timeout occurred, take action |
1970 | \& } |
2151 | \& } |
1971 | \& else |
2152 | \& else |
1972 | \& { |
2153 | \& { |
1973 | \& // callback was invoked, but there was some activity, re\-arm |
2154 | \& // callback was invoked, but there was some recent |
1974 | \& // the watcher to fire in last_activity + 60, which is |
2155 | \& // activity. simply restart the timer to time out |
1975 | \& // guaranteed to be in the future, so "again" is positive: |
2156 | \& // after "after" seconds, which is the earliest time |
1976 | \& w\->repeat = timeout \- now; |
2157 | \& // the timeout can occur. |
|
|
2158 | \& ev_timer_set (w, after, 0.); |
1977 | \& ev_timer_again (EV_A_ w); |
2159 | \& ev_timer_start (EV_A_ w); |
1978 | \& } |
2160 | \& } |
1979 | \& } |
2161 | \& } |
1980 | .Ve |
2162 | .Ve |
1981 | .Sp |
2163 | .Sp |
1982 | To summarise the callback: first calculate the real timeout (defined |
2164 | To summarise the callback: first calculate in how many seconds the |
1983 | as \*(L"60 seconds after the last activity\*(R"), then check if that time has |
2165 | timeout will occur (by calculating the absolute time when it would occur, |
1984 | been reached, which means something \fIdid\fR, in fact, time out. Otherwise |
2166 | \&\f(CW\*(C`last_activity + timeout\*(C'\fR, and subtracting the current time, \f(CW\*(C`ev_now |
1985 | the callback was invoked too early (\f(CW\*(C`timeout\*(C'\fR is in the future), so |
2167 | (EV_A)\*(C'\fR from that). |
1986 | re-schedule the timer to fire at that future time, to see if maybe we have |
|
|
1987 | a timeout then. |
|
|
1988 | .Sp |
2168 | .Sp |
1989 | Note how \f(CW\*(C`ev_timer_again\*(C'\fR is used, taking advantage of the |
2169 | If this value is negative, then we are already past the timeout, i.e. we |
1990 | \&\f(CW\*(C`ev_timer_again\*(C'\fR optimisation when the timer is already running. |
2170 | timed out, and need to do whatever is needed in this case. |
|
|
2171 | .Sp |
|
|
2172 | Otherwise, we now the earliest time at which the timeout would trigger, |
|
|
2173 | and simply start the timer with this timeout value. |
|
|
2174 | .Sp |
|
|
2175 | In other words, each time the callback is invoked it will check whether |
|
|
2176 | the timeout occurred. If not, it will simply reschedule itself to check |
|
|
2177 | again at the earliest time it could time out. Rinse. Repeat. |
1991 | .Sp |
2178 | .Sp |
1992 | This scheme causes more callback invocations (about one every 60 seconds |
2179 | This scheme causes more callback invocations (about one every 60 seconds |
1993 | minus half the average time between activity), but virtually no calls to |
2180 | minus half the average time between activity), but virtually no calls to |
1994 | libev to change the timeout. |
2181 | libev to change the timeout. |
1995 | .Sp |
2182 | .Sp |
1996 | To start the timer, simply initialise the watcher and set \f(CW\*(C`last_activity\*(C'\fR |
2183 | To start the machinery, simply initialise the watcher and set |
1997 | to the current time (meaning we just have some activity :), then call the |
2184 | \&\f(CW\*(C`last_activity\*(C'\fR to the current time (meaning there was some activity just |
1998 | callback, which will \*(L"do the right thing\*(R" and start the timer: |
2185 | now), then call the callback, which will \*(L"do the right thing\*(R" and start |
|
|
2186 | the timer: |
1999 | .Sp |
2187 | .Sp |
2000 | .Vb 3 |
2188 | .Vb 3 |
|
|
2189 | \& last_activity = ev_now (EV_A); |
2001 | \& ev_init (timer, callback); |
2190 | \& ev_init (&timer, callback); |
2002 | \& last_activity = ev_now (loop); |
2191 | \& callback (EV_A_ &timer, 0); |
2003 | \& callback (loop, timer, EV_TIMER); |
|
|
2004 | .Ve |
2192 | .Ve |
2005 | .Sp |
2193 | .Sp |
2006 | And when there is some activity, simply store the current time in |
2194 | When there is some activity, simply store the current time in |
2007 | \&\f(CW\*(C`last_activity\*(C'\fR, no libev calls at all: |
2195 | \&\f(CW\*(C`last_activity\*(C'\fR, no libev calls at all: |
2008 | .Sp |
2196 | .Sp |
2009 | .Vb 1 |
2197 | .Vb 2 |
|
|
2198 | \& if (activity detected) |
2010 | \& last_activity = ev_now (loop); |
2199 | \& last_activity = ev_now (EV_A); |
|
|
2200 | .Ve |
|
|
2201 | .Sp |
|
|
2202 | When your timeout value changes, then the timeout can be changed by simply |
|
|
2203 | providing a new value, stopping the timer and calling the callback, which |
|
|
2204 | will again do the right thing (for example, time out immediately :). |
|
|
2205 | .Sp |
|
|
2206 | .Vb 3 |
|
|
2207 | \& timeout = new_value; |
|
|
2208 | \& ev_timer_stop (EV_A_ &timer); |
|
|
2209 | \& callback (EV_A_ &timer, 0); |
2011 | .Ve |
2210 | .Ve |
2012 | .Sp |
2211 | .Sp |
2013 | This technique is slightly more complex, but in most cases where the |
2212 | This technique is slightly more complex, but in most cases where the |
2014 | time-out is unlikely to be triggered, much more efficient. |
2213 | time-out is unlikely to be triggered, much more efficient. |
2015 | .Sp |
|
|
2016 | Changing the timeout is trivial as well (if it isn't hard-coded in the |
|
|
2017 | callback :) \- just change the timeout and invoke the callback, which will |
|
|
2018 | fix things for you. |
|
|
2019 | .IP "4. Wee, just use a double-linked list for your timeouts." 4 |
2214 | .IP "4. Wee, just use a double-linked list for your timeouts." 4 |
2020 | .IX Item "4. Wee, just use a double-linked list for your timeouts." |
2215 | .IX Item "4. Wee, just use a double-linked list for your timeouts." |
2021 | If there is not one request, but many thousands (millions...), all |
2216 | If there is not one request, but many thousands (millions...), all |
2022 | employing some kind of timeout with the same timeout value, then one can |
2217 | employing some kind of timeout with the same timeout value, then one can |
2023 | do even better: |
2218 | do even better: |
… | |
… | |
2047 | Method #1 is almost always a bad idea, and buys you nothing. Method #4 is |
2242 | Method #1 is almost always a bad idea, and buys you nothing. Method #4 is |
2048 | rather complicated, but extremely efficient, something that really pays |
2243 | rather complicated, but extremely efficient, something that really pays |
2049 | off after the first million or so of active timers, i.e. it's usually |
2244 | off after the first million or so of active timers, i.e. it's usually |
2050 | overkill :) |
2245 | overkill :) |
2051 | .PP |
2246 | .PP |
|
|
2247 | \fIThe special problem of being too early\fR |
|
|
2248 | .IX Subsection "The special problem of being too early" |
|
|
2249 | .PP |
|
|
2250 | If you ask a timer to call your callback after three seconds, then |
|
|
2251 | you expect it to be invoked after three seconds \- but of course, this |
|
|
2252 | cannot be guaranteed to infinite precision. Less obviously, it cannot be |
|
|
2253 | guaranteed to any precision by libev \- imagine somebody suspending the |
|
|
2254 | process with a \s-1STOP\s0 signal for a few hours for example. |
|
|
2255 | .PP |
|
|
2256 | So, libev tries to invoke your callback as soon as possible \fIafter\fR the |
|
|
2257 | delay has occurred, but cannot guarantee this. |
|
|
2258 | .PP |
|
|
2259 | A less obvious failure mode is calling your callback too early: many event |
|
|
2260 | loops compare timestamps with a \*(L"elapsed delay >= requested delay\*(R", but |
|
|
2261 | this can cause your callback to be invoked much earlier than you would |
|
|
2262 | expect. |
|
|
2263 | .PP |
|
|
2264 | To see why, imagine a system with a clock that only offers full second |
|
|
2265 | resolution (think windows if you can't come up with a broken enough \s-1OS\s0 |
|
|
2266 | yourself). If you schedule a one-second timer at the time 500.9, then the |
|
|
2267 | event loop will schedule your timeout to elapse at a system time of 500 |
|
|
2268 | (500.9 truncated to the resolution) + 1, or 501. |
|
|
2269 | .PP |
|
|
2270 | If an event library looks at the timeout 0.1s later, it will see \*(L"501 >= |
|
|
2271 | 501\*(R" and invoke the callback 0.1s after it was started, even though a |
|
|
2272 | one-second delay was requested \- this is being \*(L"too early\*(R", despite best |
|
|
2273 | intentions. |
|
|
2274 | .PP |
|
|
2275 | This is the reason why libev will never invoke the callback if the elapsed |
|
|
2276 | delay equals the requested delay, but only when the elapsed delay is |
|
|
2277 | larger than the requested delay. In the example above, libev would only invoke |
|
|
2278 | the callback at system time 502, or 1.1s after the timer was started. |
|
|
2279 | .PP |
|
|
2280 | So, while libev cannot guarantee that your callback will be invoked |
|
|
2281 | exactly when requested, it \fIcan\fR and \fIdoes\fR guarantee that the requested |
|
|
2282 | delay has actually elapsed, or in other words, it always errs on the \*(L"too |
|
|
2283 | late\*(R" side of things. |
|
|
2284 | .PP |
2052 | \fIThe special problem of time updates\fR |
2285 | \fIThe special problem of time updates\fR |
2053 | .IX Subsection "The special problem of time updates" |
2286 | .IX Subsection "The special problem of time updates" |
2054 | .PP |
2287 | .PP |
2055 | Establishing the current time is a costly operation (it usually takes at |
2288 | Establishing the current time is a costly operation (it usually takes |
2056 | least two system calls): \s-1EV\s0 therefore updates its idea of the current |
2289 | at least one system call): \s-1EV\s0 therefore updates its idea of the current |
2057 | time only before and after \f(CW\*(C`ev_run\*(C'\fR collects new events, which causes a |
2290 | time only before and after \f(CW\*(C`ev_run\*(C'\fR collects new events, which causes a |
2058 | growing difference between \f(CW\*(C`ev_now ()\*(C'\fR and \f(CW\*(C`ev_time ()\*(C'\fR when handling |
2291 | growing difference between \f(CW\*(C`ev_now ()\*(C'\fR and \f(CW\*(C`ev_time ()\*(C'\fR when handling |
2059 | lots of events in one iteration. |
2292 | lots of events in one iteration. |
2060 | .PP |
2293 | .PP |
2061 | The relative timeouts are calculated relative to the \f(CW\*(C`ev_now ()\*(C'\fR |
2294 | The relative timeouts are calculated relative to the \f(CW\*(C`ev_now ()\*(C'\fR |
2062 | time. This is usually the right thing as this timestamp refers to the time |
2295 | time. This is usually the right thing as this timestamp refers to the time |
2063 | of the event triggering whatever timeout you are modifying/starting. If |
2296 | of the event triggering whatever timeout you are modifying/starting. If |
2064 | you suspect event processing to be delayed and you \fIneed\fR to base the |
2297 | you suspect event processing to be delayed and you \fIneed\fR to base the |
2065 | timeout on the current time, use something like this to adjust for this: |
2298 | timeout on the current time, use something like the following to adjust |
|
|
2299 | for it: |
2066 | .PP |
2300 | .PP |
2067 | .Vb 1 |
2301 | .Vb 1 |
2068 | \& ev_timer_set (&timer, after + ev_now () \- ev_time (), 0.); |
2302 | \& ev_timer_set (&timer, after + (ev_time () \- ev_now ()), 0.); |
2069 | .Ve |
2303 | .Ve |
2070 | .PP |
2304 | .PP |
2071 | If the event loop is suspended for a long time, you can also force an |
2305 | If the event loop is suspended for a long time, you can also force an |
2072 | update of the time returned by \f(CW\*(C`ev_now ()\*(C'\fR by calling \f(CW\*(C`ev_now_update |
2306 | update of the time returned by \f(CW\*(C`ev_now ()\*(C'\fR by calling \f(CW\*(C`ev_now_update |
2073 | ()\*(C'\fR. |
2307 | ()\*(C'\fR, although that will push the event time of all outstanding events |
|
|
2308 | further into the future. |
|
|
2309 | .PP |
|
|
2310 | \fIThe special problem of unsynchronised clocks\fR |
|
|
2311 | .IX Subsection "The special problem of unsynchronised clocks" |
|
|
2312 | .PP |
|
|
2313 | Modern systems have a variety of clocks \- libev itself uses the normal |
|
|
2314 | \&\*(L"wall clock\*(R" clock and, if available, the monotonic clock (to avoid time |
|
|
2315 | jumps). |
|
|
2316 | .PP |
|
|
2317 | Neither of these clocks is synchronised with each other or any other clock |
|
|
2318 | on the system, so \f(CW\*(C`ev_time ()\*(C'\fR might return a considerably different time |
|
|
2319 | than \f(CW\*(C`gettimeofday ()\*(C'\fR or \f(CW\*(C`time ()\*(C'\fR. On a GNU/Linux system, for example, |
|
|
2320 | a call to \f(CW\*(C`gettimeofday\*(C'\fR might return a second count that is one higher |
|
|
2321 | than a directly following call to \f(CW\*(C`time\*(C'\fR. |
|
|
2322 | .PP |
|
|
2323 | The moral of this is to only compare libev-related timestamps with |
|
|
2324 | \&\f(CW\*(C`ev_time ()\*(C'\fR and \f(CW\*(C`ev_now ()\*(C'\fR, at least if you want better precision than |
|
|
2325 | a second or so. |
|
|
2326 | .PP |
|
|
2327 | One more problem arises due to this lack of synchronisation: if libev uses |
|
|
2328 | the system monotonic clock and you compare timestamps from \f(CW\*(C`ev_time\*(C'\fR |
|
|
2329 | or \f(CW\*(C`ev_now\*(C'\fR from when you started your timer and when your callback is |
|
|
2330 | invoked, you will find that sometimes the callback is a bit \*(L"early\*(R". |
|
|
2331 | .PP |
|
|
2332 | This is because \f(CW\*(C`ev_timer\*(C'\fRs work in real time, not wall clock time, so |
|
|
2333 | libev makes sure your callback is not invoked before the delay happened, |
|
|
2334 | \&\fImeasured according to the real time\fR, not the system clock. |
|
|
2335 | .PP |
|
|
2336 | If your timeouts are based on a physical timescale (e.g. \*(L"time out this |
|
|
2337 | connection after 100 seconds\*(R") then this shouldn't bother you as it is |
|
|
2338 | exactly the right behaviour. |
|
|
2339 | .PP |
|
|
2340 | If you want to compare wall clock/system timestamps to your timers, then |
|
|
2341 | you need to use \f(CW\*(C`ev_periodic\*(C'\fRs, as these are based on the wall clock |
|
|
2342 | time, where your comparisons will always generate correct results. |
2074 | .PP |
2343 | .PP |
2075 | \fIThe special problems of suspended animation\fR |
2344 | \fIThe special problems of suspended animation\fR |
2076 | .IX Subsection "The special problems of suspended animation" |
2345 | .IX Subsection "The special problems of suspended animation" |
2077 | .PP |
2346 | .PP |
2078 | When you leave the server world it is quite customary to hit machines that |
2347 | When you leave the server world it is quite customary to hit machines that |
… | |
… | |
2109 | .IX Item "ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)" |
2378 | .IX Item "ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)" |
2110 | .PD 0 |
2379 | .PD 0 |
2111 | .IP "ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)" 4 |
2380 | .IP "ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)" 4 |
2112 | .IX Item "ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)" |
2381 | .IX Item "ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)" |
2113 | .PD |
2382 | .PD |
2114 | Configure the timer to trigger after \f(CW\*(C`after\*(C'\fR seconds. If \f(CW\*(C`repeat\*(C'\fR |
2383 | Configure the timer to trigger after \f(CW\*(C`after\*(C'\fR seconds (fractional and |
2115 | is \f(CW0.\fR, then it will automatically be stopped once the timeout is |
2384 | negative values are supported). If \f(CW\*(C`repeat\*(C'\fR is \f(CW0.\fR, then it will |
2116 | reached. If it is positive, then the timer will automatically be |
2385 | automatically be stopped once the timeout is reached. If it is positive, |
2117 | configured to trigger again \f(CW\*(C`repeat\*(C'\fR seconds later, again, and again, |
2386 | then the timer will automatically be configured to trigger again \f(CW\*(C`repeat\*(C'\fR |
2118 | until stopped manually. |
2387 | seconds later, again, and again, until stopped manually. |
2119 | .Sp |
2388 | .Sp |
2120 | The timer itself will do a best-effort at avoiding drift, that is, if |
2389 | The timer itself will do a best-effort at avoiding drift, that is, if |
2121 | you configure a timer to trigger every 10 seconds, then it will normally |
2390 | you configure a timer to trigger every 10 seconds, then it will normally |
2122 | trigger at exactly 10 second intervals. If, however, your program cannot |
2391 | trigger at exactly 10 second intervals. If, however, your program cannot |
2123 | keep up with the timer (because it takes longer than those 10 seconds to |
2392 | keep up with the timer (because it takes longer than those 10 seconds to |
2124 | do stuff) the timer will not fire more than once per event loop iteration. |
2393 | do stuff) the timer will not fire more than once per event loop iteration. |
2125 | .IP "ev_timer_again (loop, ev_timer *)" 4 |
2394 | .IP "ev_timer_again (loop, ev_timer *)" 4 |
2126 | .IX Item "ev_timer_again (loop, ev_timer *)" |
2395 | .IX Item "ev_timer_again (loop, ev_timer *)" |
2127 | This will act as if the timer timed out and restart it again if it is |
2396 | This will act as if the timer timed out, and restarts it again if it is |
2128 | repeating. The exact semantics are: |
2397 | repeating. It basically works like calling \f(CW\*(C`ev_timer_stop\*(C'\fR, updating the |
|
|
2398 | timeout to the \f(CW\*(C`repeat\*(C'\fR value and calling \f(CW\*(C`ev_timer_start\*(C'\fR. |
2129 | .Sp |
2399 | .Sp |
|
|
2400 | The exact semantics are as in the following rules, all of which will be |
|
|
2401 | applied to the watcher: |
|
|
2402 | .RS 4 |
2130 | If the timer is pending, its pending status is cleared. |
2403 | .IP "If the timer is pending, the pending status is always cleared." 4 |
2131 | .Sp |
2404 | .IX Item "If the timer is pending, the pending status is always cleared." |
|
|
2405 | .PD 0 |
2132 | If the timer is started but non-repeating, stop it (as if it timed out). |
2406 | .IP "If the timer is started but non-repeating, stop it (as if it timed out, without invoking it)." 4 |
2133 | .Sp |
2407 | .IX Item "If the timer is started but non-repeating, stop it (as if it timed out, without invoking it)." |
2134 | If the timer is repeating, either start it if necessary (with the |
2408 | .ie n .IP "If the timer is repeating, make the ""repeat"" value the new timeout and start the timer, if necessary." 4 |
2135 | \&\f(CW\*(C`repeat\*(C'\fR value), or reset the running timer to the \f(CW\*(C`repeat\*(C'\fR value. |
2409 | .el .IP "If the timer is repeating, make the \f(CWrepeat\fR value the new timeout and start the timer, if necessary." 4 |
|
|
2410 | .IX Item "If the timer is repeating, make the repeat value the new timeout and start the timer, if necessary." |
|
|
2411 | .RE |
|
|
2412 | .RS 4 |
|
|
2413 | .PD |
2136 | .Sp |
2414 | .Sp |
2137 | This sounds a bit complicated, see \*(L"Be smart about timeouts\*(R", above, for a |
2415 | This sounds a bit complicated, see \*(L"Be smart about timeouts\*(R", above, for a |
2138 | usage example. |
2416 | usage example. |
|
|
2417 | .RE |
2139 | .IP "ev_tstamp ev_timer_remaining (loop, ev_timer *)" 4 |
2418 | .IP "ev_tstamp ev_timer_remaining (loop, ev_timer *)" 4 |
2140 | .IX Item "ev_tstamp ev_timer_remaining (loop, ev_timer *)" |
2419 | .IX Item "ev_tstamp ev_timer_remaining (loop, ev_timer *)" |
2141 | Returns the remaining time until a timer fires. If the timer is active, |
2420 | Returns the remaining time until a timer fires. If the timer is active, |
2142 | then this time is relative to the current event loop time, otherwise it's |
2421 | then this time is relative to the current event loop time, otherwise it's |
2143 | the timeout value currently configured. |
2422 | the timeout value currently configured. |
… | |
… | |
2195 | Periodic watchers are also timers of a kind, but they are very versatile |
2474 | Periodic watchers are also timers of a kind, but they are very versatile |
2196 | (and unfortunately a bit complex). |
2475 | (and unfortunately a bit complex). |
2197 | .PP |
2476 | .PP |
2198 | Unlike \f(CW\*(C`ev_timer\*(C'\fR, periodic watchers are not based on real time (or |
2477 | Unlike \f(CW\*(C`ev_timer\*(C'\fR, periodic watchers are not based on real time (or |
2199 | relative time, the physical time that passes) but on wall clock time |
2478 | relative time, the physical time that passes) but on wall clock time |
2200 | (absolute time, the thing you can read on your calender or clock). The |
2479 | (absolute time, the thing you can read on your calendar or clock). The |
2201 | difference is that wall clock time can run faster or slower than real |
2480 | difference is that wall clock time can run faster or slower than real |
2202 | time, and time jumps are not uncommon (e.g. when you adjust your |
2481 | time, and time jumps are not uncommon (e.g. when you adjust your |
2203 | wrist-watch). |
2482 | wrist-watch). |
2204 | .PP |
2483 | .PP |
2205 | You can tell a periodic watcher to trigger after some specific point |
2484 | You can tell a periodic watcher to trigger after some specific point |
… | |
… | |
2210 | \&\f(CW\*(C`ev_timer\*(C'\fR, which would still trigger roughly 10 seconds after starting |
2489 | \&\f(CW\*(C`ev_timer\*(C'\fR, which would still trigger roughly 10 seconds after starting |
2211 | it, as it uses a relative timeout). |
2490 | it, as it uses a relative timeout). |
2212 | .PP |
2491 | .PP |
2213 | \&\f(CW\*(C`ev_periodic\*(C'\fR watchers can also be used to implement vastly more complex |
2492 | \&\f(CW\*(C`ev_periodic\*(C'\fR watchers can also be used to implement vastly more complex |
2214 | timers, such as triggering an event on each \*(L"midnight, local time\*(R", or |
2493 | timers, such as triggering an event on each \*(L"midnight, local time\*(R", or |
2215 | other complicated rules. This cannot be done with \f(CW\*(C`ev_timer\*(C'\fR watchers, as |
2494 | other complicated rules. This cannot easily be done with \f(CW\*(C`ev_timer\*(C'\fR |
2216 | those cannot react to time jumps. |
2495 | watchers, as those cannot react to time jumps. |
2217 | .PP |
2496 | .PP |
2218 | As with timers, the callback is guaranteed to be invoked only when the |
2497 | As with timers, the callback is guaranteed to be invoked only when the |
2219 | point in time where it is supposed to trigger has passed. If multiple |
2498 | point in time where it is supposed to trigger has passed. If multiple |
2220 | timers become ready during the same loop iteration then the ones with |
2499 | timers become ready during the same loop iteration then the ones with |
2221 | earlier time-out values are invoked before ones with later time-out values |
2500 | earlier time-out values are invoked before ones with later time-out values |
… | |
… | |
2263 | .Sp |
2542 | .Sp |
2264 | Another way to think about it (for the mathematically inclined) is that |
2543 | Another way to think about it (for the mathematically inclined) is that |
2265 | \&\f(CW\*(C`ev_periodic\*(C'\fR will try to run the callback in this mode at the next possible |
2544 | \&\f(CW\*(C`ev_periodic\*(C'\fR will try to run the callback in this mode at the next possible |
2266 | time where \f(CW\*(C`time = offset (mod interval)\*(C'\fR, regardless of any time jumps. |
2545 | time where \f(CW\*(C`time = offset (mod interval)\*(C'\fR, regardless of any time jumps. |
2267 | .Sp |
2546 | .Sp |
2268 | For numerical stability it is preferable that the \f(CW\*(C`offset\*(C'\fR value is near |
2547 | The \f(CW\*(C`interval\*(C'\fR \fI\s-1MUST\s0\fR be positive, and for numerical stability, the |
2269 | \&\f(CW\*(C`ev_now ()\*(C'\fR (the current time), but there is no range requirement for |
2548 | interval value should be higher than \f(CW\*(C`1/8192\*(C'\fR (which is around 100 |
2270 | this value, and in fact is often specified as zero. |
2549 | microseconds) and \f(CW\*(C`offset\*(C'\fR should be higher than \f(CW0\fR and should have |
|
|
2550 | at most a similar magnitude as the current time (say, within a factor of |
|
|
2551 | ten). Typical values for offset are, in fact, \f(CW0\fR or something between |
|
|
2552 | \&\f(CW0\fR and \f(CW\*(C`interval\*(C'\fR, which is also the recommended range. |
2271 | .Sp |
2553 | .Sp |
2272 | Note also that there is an upper limit to how often a timer can fire (\s-1CPU\s0 |
2554 | Note also that there is an upper limit to how often a timer can fire (\s-1CPU\s0 |
2273 | speed for example), so if \f(CW\*(C`interval\*(C'\fR is very small then timing stability |
2555 | speed for example), so if \f(CW\*(C`interval\*(C'\fR is very small then timing stability |
2274 | will of course deteriorate. Libev itself tries to be exact to be about one |
2556 | will of course deteriorate. Libev itself tries to be exact to be about one |
2275 | millisecond (if the \s-1OS\s0 supports it and the machine is fast enough). |
2557 | millisecond (if the \s-1OS\s0 supports it and the machine is fast enough). |
… | |
… | |
2279 | In this mode the values for \f(CW\*(C`interval\*(C'\fR and \f(CW\*(C`offset\*(C'\fR are both being |
2561 | In this mode the values for \f(CW\*(C`interval\*(C'\fR and \f(CW\*(C`offset\*(C'\fR are both being |
2280 | ignored. Instead, each time the periodic watcher gets scheduled, the |
2562 | ignored. Instead, each time the periodic watcher gets scheduled, the |
2281 | reschedule callback will be called with the watcher as first, and the |
2563 | reschedule callback will be called with the watcher as first, and the |
2282 | current time as second argument. |
2564 | current time as second argument. |
2283 | .Sp |
2565 | .Sp |
2284 | \&\s-1NOTE:\s0 \fIThis callback \s-1MUST\s0 \s-1NOT\s0 stop or destroy any periodic watcher, ever, |
2566 | \&\s-1NOTE:\s0 \fIThis callback \s-1MUST NOT\s0 stop or destroy any periodic watcher, ever, |
2285 | or make \s-1ANY\s0 other event loop modifications whatsoever, unless explicitly |
2567 | or make \s-1ANY\s0 other event loop modifications whatsoever, unless explicitly |
2286 | allowed by documentation here\fR. |
2568 | allowed by documentation here\fR. |
2287 | .Sp |
2569 | .Sp |
2288 | If you need to stop it, return \f(CW\*(C`now + 1e30\*(C'\fR (or so, fudge fudge) and stop |
2570 | If you need to stop it, return \f(CW\*(C`now + 1e30\*(C'\fR (or so, fudge fudge) and stop |
2289 | it afterwards (e.g. by starting an \f(CW\*(C`ev_prepare\*(C'\fR watcher, which is the |
2571 | it afterwards (e.g. by starting an \f(CW\*(C`ev_prepare\*(C'\fR watcher, which is the |
… | |
… | |
2307 | .Sp |
2589 | .Sp |
2308 | \&\s-1NOTE:\s0 \fIThis callback must always return a time that is higher than or |
2590 | \&\s-1NOTE:\s0 \fIThis callback must always return a time that is higher than or |
2309 | equal to the passed \f(CI\*(C`now\*(C'\fI value\fR. |
2591 | equal to the passed \f(CI\*(C`now\*(C'\fI value\fR. |
2310 | .Sp |
2592 | .Sp |
2311 | This can be used to create very complex timers, such as a timer that |
2593 | This can be used to create very complex timers, such as a timer that |
2312 | triggers on \*(L"next midnight, local time\*(R". To do this, you would calculate the |
2594 | triggers on \*(L"next midnight, local time\*(R". To do this, you would calculate |
2313 | next midnight after \f(CW\*(C`now\*(C'\fR and return the timestamp value for this. How |
2595 | the next midnight after \f(CW\*(C`now\*(C'\fR and return the timestamp value for |
2314 | you do this is, again, up to you (but it is not trivial, which is the main |
2596 | this. Here is a (completely untested, no error checking) example on how to |
2315 | reason I omitted it as an example). |
2597 | do this: |
|
|
2598 | .Sp |
|
|
2599 | .Vb 1 |
|
|
2600 | \& #include <time.h> |
|
|
2601 | \& |
|
|
2602 | \& static ev_tstamp |
|
|
2603 | \& my_rescheduler (ev_periodic *w, ev_tstamp now) |
|
|
2604 | \& { |
|
|
2605 | \& time_t tnow = (time_t)now; |
|
|
2606 | \& struct tm tm; |
|
|
2607 | \& localtime_r (&tnow, &tm); |
|
|
2608 | \& |
|
|
2609 | \& tm.tm_sec = tm.tm_min = tm.tm_hour = 0; // midnight current day |
|
|
2610 | \& ++tm.tm_mday; // midnight next day |
|
|
2611 | \& |
|
|
2612 | \& return mktime (&tm); |
|
|
2613 | \& } |
|
|
2614 | .Ve |
|
|
2615 | .Sp |
|
|
2616 | Note: this code might run into trouble on days that have more then two |
|
|
2617 | midnights (beginning and end). |
2316 | .RE |
2618 | .RE |
2317 | .RS 4 |
2619 | .RS 4 |
2318 | .RE |
2620 | .RE |
2319 | .IP "ev_periodic_again (loop, ev_periodic *)" 4 |
2621 | .IP "ev_periodic_again (loop, ev_periodic *)" 4 |
2320 | .IX Item "ev_periodic_again (loop, ev_periodic *)" |
2622 | .IX Item "ev_periodic_again (loop, ev_periodic *)" |
… | |
… | |
2391 | .ie n .SS """ev_signal"" \- signal me when a signal gets signalled!" |
2693 | .ie n .SS """ev_signal"" \- signal me when a signal gets signalled!" |
2392 | .el .SS "\f(CWev_signal\fP \- signal me when a signal gets signalled!" |
2694 | .el .SS "\f(CWev_signal\fP \- signal me when a signal gets signalled!" |
2393 | .IX Subsection "ev_signal - signal me when a signal gets signalled!" |
2695 | .IX Subsection "ev_signal - signal me when a signal gets signalled!" |
2394 | Signal watchers will trigger an event when the process receives a specific |
2696 | Signal watchers will trigger an event when the process receives a specific |
2395 | signal one or more times. Even though signals are very asynchronous, libev |
2697 | signal one or more times. Even though signals are very asynchronous, libev |
2396 | will try it's best to deliver signals synchronously, i.e. as part of the |
2698 | will try its best to deliver signals synchronously, i.e. as part of the |
2397 | normal event processing, like any other event. |
2699 | normal event processing, like any other event. |
2398 | .PP |
2700 | .PP |
2399 | If you want signals to be delivered truly asynchronously, just use |
2701 | If you want signals to be delivered truly asynchronously, just use |
2400 | \&\f(CW\*(C`sigaction\*(C'\fR as you would do without libev and forget about sharing |
2702 | \&\f(CW\*(C`sigaction\*(C'\fR as you would do without libev and forget about sharing |
2401 | the signal. You can even use \f(CW\*(C`ev_async\*(C'\fR from a signal handler to |
2703 | the signal. You can even use \f(CW\*(C`ev_async\*(C'\fR from a signal handler to |
… | |
… | |
2405 | only within the same loop, i.e. you can watch for \f(CW\*(C`SIGINT\*(C'\fR in your |
2707 | only within the same loop, i.e. you can watch for \f(CW\*(C`SIGINT\*(C'\fR in your |
2406 | default loop and for \f(CW\*(C`SIGIO\*(C'\fR in another loop, but you cannot watch for |
2708 | default loop and for \f(CW\*(C`SIGIO\*(C'\fR in another loop, but you cannot watch for |
2407 | \&\f(CW\*(C`SIGINT\*(C'\fR in both the default loop and another loop at the same time. At |
2709 | \&\f(CW\*(C`SIGINT\*(C'\fR in both the default loop and another loop at the same time. At |
2408 | the moment, \f(CW\*(C`SIGCHLD\*(C'\fR is permanently tied to the default loop. |
2710 | the moment, \f(CW\*(C`SIGCHLD\*(C'\fR is permanently tied to the default loop. |
2409 | .PP |
2711 | .PP |
2410 | When the first watcher gets started will libev actually register something |
2712 | Only after the first watcher for a signal is started will libev actually |
2411 | with the kernel (thus it coexists with your own signal handlers as long as |
2713 | register something with the kernel. It thus coexists with your own signal |
2412 | you don't register any with libev for the same signal). |
2714 | handlers as long as you don't register any with libev for the same signal. |
2413 | .PP |
2715 | .PP |
2414 | If possible and supported, libev will install its handlers with |
2716 | If possible and supported, libev will install its handlers with |
2415 | \&\f(CW\*(C`SA_RESTART\*(C'\fR (or equivalent) behaviour enabled, so system calls should |
2717 | \&\f(CW\*(C`SA_RESTART\*(C'\fR (or equivalent) behaviour enabled, so system calls should |
2416 | not be unduly interrupted. If you have a problem with system calls getting |
2718 | not be unduly interrupted. If you have a problem with system calls getting |
2417 | interrupted by signals you can block all signals in an \f(CW\*(C`ev_check\*(C'\fR watcher |
2719 | interrupted by signals you can block all signals in an \f(CW\*(C`ev_check\*(C'\fR watcher |
… | |
… | |
2421 | .IX Subsection "The special problem of inheritance over fork/execve/pthread_create" |
2723 | .IX Subsection "The special problem of inheritance over fork/execve/pthread_create" |
2422 | .PP |
2724 | .PP |
2423 | Both the signal mask (\f(CW\*(C`sigprocmask\*(C'\fR) and the signal disposition |
2725 | Both the signal mask (\f(CW\*(C`sigprocmask\*(C'\fR) and the signal disposition |
2424 | (\f(CW\*(C`sigaction\*(C'\fR) are unspecified after starting a signal watcher (and after |
2726 | (\f(CW\*(C`sigaction\*(C'\fR) are unspecified after starting a signal watcher (and after |
2425 | stopping it again), that is, libev might or might not block the signal, |
2727 | stopping it again), that is, libev might or might not block the signal, |
2426 | and might or might not set or restore the installed signal handler. |
2728 | and might or might not set or restore the installed signal handler (but |
|
|
2729 | see \f(CW\*(C`EVFLAG_NOSIGMASK\*(C'\fR). |
2427 | .PP |
2730 | .PP |
2428 | While this does not matter for the signal disposition (libev never |
2731 | While this does not matter for the signal disposition (libev never |
2429 | sets signals to \f(CW\*(C`SIG_IGN\*(C'\fR, so handlers will be reset to \f(CW\*(C`SIG_DFL\*(C'\fR on |
2732 | sets signals to \f(CW\*(C`SIG_IGN\*(C'\fR, so handlers will be reset to \f(CW\*(C`SIG_DFL\*(C'\fR on |
2430 | \&\f(CW\*(C`execve\*(C'\fR), this matters for the signal mask: many programs do not expect |
2733 | \&\f(CW\*(C`execve\*(C'\fR), this matters for the signal mask: many programs do not expect |
2431 | certain signals to be blocked. |
2734 | certain signals to be blocked. |
… | |
… | |
2444 | \&\fIhas\fR to modify the signal mask, at least temporarily. |
2747 | \&\fIhas\fR to modify the signal mask, at least temporarily. |
2445 | .PP |
2748 | .PP |
2446 | So I can't stress this enough: \fIIf you do not reset your signal mask when |
2749 | So I can't stress this enough: \fIIf you do not reset your signal mask when |
2447 | you expect it to be empty, you have a race condition in your code\fR. This |
2750 | you expect it to be empty, you have a race condition in your code\fR. This |
2448 | is not a libev-specific thing, this is true for most event libraries. |
2751 | is not a libev-specific thing, this is true for most event libraries. |
|
|
2752 | .PP |
|
|
2753 | \fIThe special problem of threads signal handling\fR |
|
|
2754 | .IX Subsection "The special problem of threads signal handling" |
|
|
2755 | .PP |
|
|
2756 | \&\s-1POSIX\s0 threads has problematic signal handling semantics, specifically, |
|
|
2757 | a lot of functionality (sigfd, sigwait etc.) only really works if all |
|
|
2758 | threads in a process block signals, which is hard to achieve. |
|
|
2759 | .PP |
|
|
2760 | When you want to use sigwait (or mix libev signal handling with your own |
|
|
2761 | for the same signals), you can tackle this problem by globally blocking |
|
|
2762 | all signals before creating any threads (or creating them with a fully set |
|
|
2763 | sigprocmask) and also specifying the \f(CW\*(C`EVFLAG_NOSIGMASK\*(C'\fR when creating |
|
|
2764 | loops. Then designate one thread as \*(L"signal receiver thread\*(R" which handles |
|
|
2765 | these signals. You can pass on any signals that libev might be interested |
|
|
2766 | in by calling \f(CW\*(C`ev_feed_signal\*(C'\fR. |
2449 | .PP |
2767 | .PP |
2450 | \fIWatcher-Specific Functions and Data Members\fR |
2768 | \fIWatcher-Specific Functions and Data Members\fR |
2451 | .IX Subsection "Watcher-Specific Functions and Data Members" |
2769 | .IX Subsection "Watcher-Specific Functions and Data Members" |
2452 | .IP "ev_signal_init (ev_signal *, callback, int signum)" 4 |
2770 | .IP "ev_signal_init (ev_signal *, callback, int signum)" 4 |
2453 | .IX Item "ev_signal_init (ev_signal *, callback, int signum)" |
2771 | .IX Item "ev_signal_init (ev_signal *, callback, int signum)" |
… | |
… | |
2462 | The signal the watcher watches out for. |
2780 | The signal the watcher watches out for. |
2463 | .PP |
2781 | .PP |
2464 | \fIExamples\fR |
2782 | \fIExamples\fR |
2465 | .IX Subsection "Examples" |
2783 | .IX Subsection "Examples" |
2466 | .PP |
2784 | .PP |
2467 | Example: Try to exit cleanly on \s-1SIGINT\s0. |
2785 | Example: Try to exit cleanly on \s-1SIGINT.\s0 |
2468 | .PP |
2786 | .PP |
2469 | .Vb 5 |
2787 | .Vb 5 |
2470 | \& static void |
2788 | \& static void |
2471 | \& sigint_cb (struct ev_loop *loop, ev_signal *w, int revents) |
2789 | \& sigint_cb (struct ev_loop *loop, ev_signal *w, int revents) |
2472 | \& { |
2790 | \& { |
… | |
… | |
2587 | .ie n .SS """ev_stat"" \- did the file attributes just change?" |
2905 | .ie n .SS """ev_stat"" \- did the file attributes just change?" |
2588 | .el .SS "\f(CWev_stat\fP \- did the file attributes just change?" |
2906 | .el .SS "\f(CWev_stat\fP \- did the file attributes just change?" |
2589 | .IX Subsection "ev_stat - did the file attributes just change?" |
2907 | .IX Subsection "ev_stat - did the file attributes just change?" |
2590 | This watches a file system path for attribute changes. That is, it calls |
2908 | This watches a file system path for attribute changes. That is, it calls |
2591 | \&\f(CW\*(C`stat\*(C'\fR on that path in regular intervals (or when the \s-1OS\s0 says it changed) |
2909 | \&\f(CW\*(C`stat\*(C'\fR on that path in regular intervals (or when the \s-1OS\s0 says it changed) |
2592 | and sees if it changed compared to the last time, invoking the callback if |
2910 | and sees if it changed compared to the last time, invoking the callback |
2593 | it did. |
2911 | if it did. Starting the watcher \f(CW\*(C`stat\*(C'\fR's the file, so only changes that |
|
|
2912 | happen after the watcher has been started will be reported. |
2594 | .PP |
2913 | .PP |
2595 | The path does not need to exist: changing from \*(L"path exists\*(R" to \*(L"path does |
2914 | The path does not need to exist: changing from \*(L"path exists\*(R" to \*(L"path does |
2596 | not exist\*(R" is a status change like any other. The condition \*(L"path does not |
2915 | not exist\*(R" is a status change like any other. The condition \*(L"path does not |
2597 | exist\*(R" (or more correctly \*(L"path cannot be stat'ed\*(R") is signified by the |
2916 | exist\*(R" (or more correctly \*(L"path cannot be stat'ed\*(R") is signified by the |
2598 | \&\f(CW\*(C`st_nlink\*(C'\fR field being zero (which is otherwise always forced to be at |
2917 | \&\f(CW\*(C`st_nlink\*(C'\fR field being zero (which is otherwise always forced to be at |
… | |
… | |
2628 | compilation environment, which means that on systems with large file |
2947 | compilation environment, which means that on systems with large file |
2629 | support disabled by default, you get the 32 bit version of the stat |
2948 | support disabled by default, you get the 32 bit version of the stat |
2630 | structure. When using the library from programs that change the \s-1ABI\s0 to |
2949 | structure. When using the library from programs that change the \s-1ABI\s0 to |
2631 | use 64 bit file offsets the programs will fail. In that case you have to |
2950 | use 64 bit file offsets the programs will fail. In that case you have to |
2632 | compile libev with the same flags to get binary compatibility. This is |
2951 | compile libev with the same flags to get binary compatibility. This is |
2633 | obviously the case with any flags that change the \s-1ABI\s0, but the problem is |
2952 | obviously the case with any flags that change the \s-1ABI,\s0 but the problem is |
2634 | most noticeably displayed with ev_stat and large file support. |
2953 | most noticeably displayed with ev_stat and large file support. |
2635 | .PP |
2954 | .PP |
2636 | The solution for this is to lobby your distribution maker to make large |
2955 | The solution for this is to lobby your distribution maker to make large |
2637 | file interfaces available by default (as e.g. FreeBSD does) and not |
2956 | file interfaces available by default (as e.g. FreeBSD does) and not |
2638 | optional. Libev cannot simply switch on large file support because it has |
2957 | optional. Libev cannot simply switch on large file support because it has |
… | |
… | |
2829 | Apart from keeping your process non-blocking (which is a useful |
3148 | Apart from keeping your process non-blocking (which is a useful |
2830 | effect on its own sometimes), idle watchers are a good place to do |
3149 | effect on its own sometimes), idle watchers are a good place to do |
2831 | \&\*(L"pseudo-background processing\*(R", or delay processing stuff to after the |
3150 | \&\*(L"pseudo-background processing\*(R", or delay processing stuff to after the |
2832 | event loop has handled all outstanding events. |
3151 | event loop has handled all outstanding events. |
2833 | .PP |
3152 | .PP |
|
|
3153 | \fIAbusing an \f(CI\*(C`ev_idle\*(C'\fI watcher for its side-effect\fR |
|
|
3154 | .IX Subsection "Abusing an ev_idle watcher for its side-effect" |
|
|
3155 | .PP |
|
|
3156 | As long as there is at least one active idle watcher, libev will never |
|
|
3157 | sleep unnecessarily. Or in other words, it will loop as fast as possible. |
|
|
3158 | For this to work, the idle watcher doesn't need to be invoked at all \- the |
|
|
3159 | lowest priority will do. |
|
|
3160 | .PP |
|
|
3161 | This mode of operation can be useful together with an \f(CW\*(C`ev_check\*(C'\fR watcher, |
|
|
3162 | to do something on each event loop iteration \- for example to balance load |
|
|
3163 | between different connections. |
|
|
3164 | .PP |
|
|
3165 | See \*(L"Abusing an ev_check watcher for its side-effect\*(R" for a longer |
|
|
3166 | example. |
|
|
3167 | .PP |
2834 | \fIWatcher-Specific Functions and Data Members\fR |
3168 | \fIWatcher-Specific Functions and Data Members\fR |
2835 | .IX Subsection "Watcher-Specific Functions and Data Members" |
3169 | .IX Subsection "Watcher-Specific Functions and Data Members" |
2836 | .IP "ev_idle_init (ev_idle *, callback)" 4 |
3170 | .IP "ev_idle_init (ev_idle *, callback)" 4 |
2837 | .IX Item "ev_idle_init (ev_idle *, callback)" |
3171 | .IX Item "ev_idle_init (ev_idle *, callback)" |
2838 | Initialises and configures the idle watcher \- it has no parameters of any |
3172 | Initialises and configures the idle watcher \- it has no parameters of any |
… | |
… | |
2843 | .IX Subsection "Examples" |
3177 | .IX Subsection "Examples" |
2844 | .PP |
3178 | .PP |
2845 | Example: Dynamically allocate an \f(CW\*(C`ev_idle\*(C'\fR watcher, start it, and in the |
3179 | Example: Dynamically allocate an \f(CW\*(C`ev_idle\*(C'\fR watcher, start it, and in the |
2846 | callback, free it. Also, use no error checking, as usual. |
3180 | callback, free it. Also, use no error checking, as usual. |
2847 | .PP |
3181 | .PP |
2848 | .Vb 7 |
3182 | .Vb 5 |
2849 | \& static void |
3183 | \& static void |
2850 | \& idle_cb (struct ev_loop *loop, ev_idle *w, int revents) |
3184 | \& idle_cb (struct ev_loop *loop, ev_idle *w, int revents) |
2851 | \& { |
3185 | \& { |
|
|
3186 | \& // stop the watcher |
|
|
3187 | \& ev_idle_stop (loop, w); |
|
|
3188 | \& |
|
|
3189 | \& // now we can free it |
2852 | \& free (w); |
3190 | \& free (w); |
|
|
3191 | \& |
2853 | \& // now do something you wanted to do when the program has |
3192 | \& // now do something you wanted to do when the program has |
2854 | \& // no longer anything immediate to do. |
3193 | \& // no longer anything immediate to do. |
2855 | \& } |
3194 | \& } |
2856 | \& |
3195 | \& |
2857 | \& ev_idle *idle_watcher = malloc (sizeof (ev_idle)); |
3196 | \& ev_idle *idle_watcher = malloc (sizeof (ev_idle)); |
… | |
… | |
2859 | \& ev_idle_start (loop, idle_watcher); |
3198 | \& ev_idle_start (loop, idle_watcher); |
2860 | .Ve |
3199 | .Ve |
2861 | .ie n .SS """ev_prepare"" and ""ev_check"" \- customise your event loop!" |
3200 | .ie n .SS """ev_prepare"" and ""ev_check"" \- customise your event loop!" |
2862 | .el .SS "\f(CWev_prepare\fP and \f(CWev_check\fP \- customise your event loop!" |
3201 | .el .SS "\f(CWev_prepare\fP and \f(CWev_check\fP \- customise your event loop!" |
2863 | .IX Subsection "ev_prepare and ev_check - customise your event loop!" |
3202 | .IX Subsection "ev_prepare and ev_check - customise your event loop!" |
2864 | Prepare and check watchers are usually (but not always) used in pairs: |
3203 | Prepare and check watchers are often (but not always) used in pairs: |
2865 | prepare watchers get invoked before the process blocks and check watchers |
3204 | prepare watchers get invoked before the process blocks and check watchers |
2866 | afterwards. |
3205 | afterwards. |
2867 | .PP |
3206 | .PP |
2868 | You \fImust not\fR call \f(CW\*(C`ev_run\*(C'\fR or similar functions that enter |
3207 | You \fImust not\fR call \f(CW\*(C`ev_run\*(C'\fR (or similar functions that enter the |
2869 | the current event loop from either \f(CW\*(C`ev_prepare\*(C'\fR or \f(CW\*(C`ev_check\*(C'\fR |
3208 | current event loop) or \f(CW\*(C`ev_loop_fork\*(C'\fR from either \f(CW\*(C`ev_prepare\*(C'\fR or |
2870 | watchers. Other loops than the current one are fine, however. The |
3209 | \&\f(CW\*(C`ev_check\*(C'\fR watchers. Other loops than the current one are fine, |
2871 | rationale behind this is that you do not need to check for recursion in |
3210 | however. The rationale behind this is that you do not need to check |
2872 | those watchers, i.e. the sequence will always be \f(CW\*(C`ev_prepare\*(C'\fR, blocking, |
3211 | for recursion in those watchers, i.e. the sequence will always be |
2873 | \&\f(CW\*(C`ev_check\*(C'\fR so if you have one watcher of each kind they will always be |
3212 | \&\f(CW\*(C`ev_prepare\*(C'\fR, blocking, \f(CW\*(C`ev_check\*(C'\fR so if you have one watcher of each |
2874 | called in pairs bracketing the blocking call. |
3213 | kind they will always be called in pairs bracketing the blocking call. |
2875 | .PP |
3214 | .PP |
2876 | Their main purpose is to integrate other event mechanisms into libev and |
3215 | Their main purpose is to integrate other event mechanisms into libev and |
2877 | their use is somewhat advanced. They could be used, for example, to track |
3216 | their use is somewhat advanced. They could be used, for example, to track |
2878 | variable changes, implement your own watchers, integrate net-snmp or a |
3217 | variable changes, implement your own watchers, integrate net-snmp or a |
2879 | coroutine library and lots more. They are also occasionally useful if |
3218 | coroutine library and lots more. They are also occasionally useful if |
… | |
… | |
2897 | with priority higher than or equal to the event loop and one coroutine |
3236 | with priority higher than or equal to the event loop and one coroutine |
2898 | of lower priority, but only once, using idle watchers to keep the event |
3237 | of lower priority, but only once, using idle watchers to keep the event |
2899 | loop from blocking if lower-priority coroutines are active, thus mapping |
3238 | loop from blocking if lower-priority coroutines are active, thus mapping |
2900 | low-priority coroutines to idle/background tasks). |
3239 | low-priority coroutines to idle/background tasks). |
2901 | .PP |
3240 | .PP |
2902 | It is recommended to give \f(CW\*(C`ev_check\*(C'\fR watchers highest (\f(CW\*(C`EV_MAXPRI\*(C'\fR) |
3241 | When used for this purpose, it is recommended to give \f(CW\*(C`ev_check\*(C'\fR watchers |
2903 | priority, to ensure that they are being run before any other watchers |
3242 | highest (\f(CW\*(C`EV_MAXPRI\*(C'\fR) priority, to ensure that they are being run before |
2904 | after the poll (this doesn't matter for \f(CW\*(C`ev_prepare\*(C'\fR watchers). |
3243 | any other watchers after the poll (this doesn't matter for \f(CW\*(C`ev_prepare\*(C'\fR |
|
|
3244 | watchers). |
2905 | .PP |
3245 | .PP |
2906 | Also, \f(CW\*(C`ev_check\*(C'\fR watchers (and \f(CW\*(C`ev_prepare\*(C'\fR watchers, too) should not |
3246 | Also, \f(CW\*(C`ev_check\*(C'\fR watchers (and \f(CW\*(C`ev_prepare\*(C'\fR watchers, too) should not |
2907 | activate (\*(L"feed\*(R") events into libev. While libev fully supports this, they |
3247 | activate (\*(L"feed\*(R") events into libev. While libev fully supports this, they |
2908 | might get executed before other \f(CW\*(C`ev_check\*(C'\fR watchers did their job. As |
3248 | might get executed before other \f(CW\*(C`ev_check\*(C'\fR watchers did their job. As |
2909 | \&\f(CW\*(C`ev_check\*(C'\fR watchers are often used to embed other (non-libev) event |
3249 | \&\f(CW\*(C`ev_check\*(C'\fR watchers are often used to embed other (non-libev) event |
2910 | loops those other event loops might be in an unusable state until their |
3250 | loops those other event loops might be in an unusable state until their |
2911 | \&\f(CW\*(C`ev_check\*(C'\fR watcher ran (always remind yourself to coexist peacefully with |
3251 | \&\f(CW\*(C`ev_check\*(C'\fR watcher ran (always remind yourself to coexist peacefully with |
2912 | others). |
3252 | others). |
|
|
3253 | .PP |
|
|
3254 | \fIAbusing an \f(CI\*(C`ev_check\*(C'\fI watcher for its side-effect\fR |
|
|
3255 | .IX Subsection "Abusing an ev_check watcher for its side-effect" |
|
|
3256 | .PP |
|
|
3257 | \&\f(CW\*(C`ev_check\*(C'\fR (and less often also \f(CW\*(C`ev_prepare\*(C'\fR) watchers can also be |
|
|
3258 | useful because they are called once per event loop iteration. For |
|
|
3259 | example, if you want to handle a large number of connections fairly, you |
|
|
3260 | normally only do a bit of work for each active connection, and if there |
|
|
3261 | is more work to do, you wait for the next event loop iteration, so other |
|
|
3262 | connections have a chance of making progress. |
|
|
3263 | .PP |
|
|
3264 | Using an \f(CW\*(C`ev_check\*(C'\fR watcher is almost enough: it will be called on the |
|
|
3265 | next event loop iteration. However, that isn't as soon as possible \- |
|
|
3266 | without external events, your \f(CW\*(C`ev_check\*(C'\fR watcher will not be invoked. |
|
|
3267 | .PP |
|
|
3268 | This is where \f(CW\*(C`ev_idle\*(C'\fR watchers come in handy \- all you need is a |
|
|
3269 | single global idle watcher that is active as long as you have one active |
|
|
3270 | \&\f(CW\*(C`ev_check\*(C'\fR watcher. The \f(CW\*(C`ev_idle\*(C'\fR watcher makes sure the event loop |
|
|
3271 | will not sleep, and the \f(CW\*(C`ev_check\*(C'\fR watcher makes sure a callback gets |
|
|
3272 | invoked. Neither watcher alone can do that. |
2913 | .PP |
3273 | .PP |
2914 | \fIWatcher-Specific Functions and Data Members\fR |
3274 | \fIWatcher-Specific Functions and Data Members\fR |
2915 | .IX Subsection "Watcher-Specific Functions and Data Members" |
3275 | .IX Subsection "Watcher-Specific Functions and Data Members" |
2916 | .IP "ev_prepare_init (ev_prepare *, callback)" 4 |
3276 | .IP "ev_prepare_init (ev_prepare *, callback)" 4 |
2917 | .IX Item "ev_prepare_init (ev_prepare *, callback)" |
3277 | .IX Item "ev_prepare_init (ev_prepare *, callback)" |
… | |
… | |
3028 | .Ve |
3388 | .Ve |
3029 | .PP |
3389 | .PP |
3030 | Method 4: Do not use a prepare or check watcher because the module you |
3390 | Method 4: Do not use a prepare or check watcher because the module you |
3031 | want to embed is not flexible enough to support it. Instead, you can |
3391 | want to embed is not flexible enough to support it. Instead, you can |
3032 | override their poll function. The drawback with this solution is that the |
3392 | override their poll function. The drawback with this solution is that the |
3033 | main loop is now no longer controllable by \s-1EV\s0. The \f(CW\*(C`Glib::EV\*(C'\fR module uses |
3393 | main loop is now no longer controllable by \s-1EV.\s0 The \f(CW\*(C`Glib::EV\*(C'\fR module uses |
3034 | this approach, effectively embedding \s-1EV\s0 as a client into the horrible |
3394 | this approach, effectively embedding \s-1EV\s0 as a client into the horrible |
3035 | libglib event loop. |
3395 | libglib event loop. |
3036 | .PP |
3396 | .PP |
3037 | .Vb 4 |
3397 | .Vb 4 |
3038 | \& static gint |
3398 | \& static gint |
… | |
… | |
3122 | \fIWatcher-Specific Functions and Data Members\fR |
3482 | \fIWatcher-Specific Functions and Data Members\fR |
3123 | .IX Subsection "Watcher-Specific Functions and Data Members" |
3483 | .IX Subsection "Watcher-Specific Functions and Data Members" |
3124 | .IP "ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)" 4 |
3484 | .IP "ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)" 4 |
3125 | .IX Item "ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)" |
3485 | .IX Item "ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)" |
3126 | .PD 0 |
3486 | .PD 0 |
3127 | .IP "ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)" 4 |
3487 | .IP "ev_embed_set (ev_embed *, struct ev_loop *embedded_loop)" 4 |
3128 | .IX Item "ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)" |
3488 | .IX Item "ev_embed_set (ev_embed *, struct ev_loop *embedded_loop)" |
3129 | .PD |
3489 | .PD |
3130 | Configures the watcher to embed the given loop, which must be |
3490 | Configures the watcher to embed the given loop, which must be |
3131 | embeddable. If the callback is \f(CW0\fR, then \f(CW\*(C`ev_embed_sweep\*(C'\fR will be |
3491 | embeddable. If the callback is \f(CW0\fR, then \f(CW\*(C`ev_embed_sweep\*(C'\fR will be |
3132 | invoked automatically, otherwise it is the responsibility of the callback |
3492 | invoked automatically, otherwise it is the responsibility of the callback |
3133 | to invoke it (it will continue to be called until the sweep has been done, |
3493 | to invoke it (it will continue to be called until the sweep has been done, |
… | |
… | |
3152 | .PP |
3512 | .PP |
3153 | .Vb 3 |
3513 | .Vb 3 |
3154 | \& struct ev_loop *loop_hi = ev_default_init (0); |
3514 | \& struct ev_loop *loop_hi = ev_default_init (0); |
3155 | \& struct ev_loop *loop_lo = 0; |
3515 | \& struct ev_loop *loop_lo = 0; |
3156 | \& ev_embed embed; |
3516 | \& ev_embed embed; |
3157 | \& |
3517 | \& |
3158 | \& // see if there is a chance of getting one that works |
3518 | \& // see if there is a chance of getting one that works |
3159 | \& // (remember that a flags value of 0 means autodetection) |
3519 | \& // (remember that a flags value of 0 means autodetection) |
3160 | \& loop_lo = ev_embeddable_backends () & ev_recommended_backends () |
3520 | \& loop_lo = ev_embeddable_backends () & ev_recommended_backends () |
3161 | \& ? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ()) |
3521 | \& ? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ()) |
3162 | \& : 0; |
3522 | \& : 0; |
… | |
… | |
3178 | .PP |
3538 | .PP |
3179 | .Vb 3 |
3539 | .Vb 3 |
3180 | \& struct ev_loop *loop = ev_default_init (0); |
3540 | \& struct ev_loop *loop = ev_default_init (0); |
3181 | \& struct ev_loop *loop_socket = 0; |
3541 | \& struct ev_loop *loop_socket = 0; |
3182 | \& ev_embed embed; |
3542 | \& ev_embed embed; |
3183 | \& |
3543 | \& |
3184 | \& if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE) |
3544 | \& if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE) |
3185 | \& if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE)) |
3545 | \& if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE)) |
3186 | \& { |
3546 | \& { |
3187 | \& ev_embed_init (&embed, 0, loop_socket); |
3547 | \& ev_embed_init (&embed, 0, loop_socket); |
3188 | \& ev_embed_start (loop, &embed); |
3548 | \& ev_embed_start (loop, &embed); |
… | |
… | |
3196 | .ie n .SS """ev_fork"" \- the audacity to resume the event loop after a fork" |
3556 | .ie n .SS """ev_fork"" \- the audacity to resume the event loop after a fork" |
3197 | .el .SS "\f(CWev_fork\fP \- the audacity to resume the event loop after a fork" |
3557 | .el .SS "\f(CWev_fork\fP \- the audacity to resume the event loop after a fork" |
3198 | .IX Subsection "ev_fork - the audacity to resume the event loop after a fork" |
3558 | .IX Subsection "ev_fork - the audacity to resume the event loop after a fork" |
3199 | Fork watchers are called when a \f(CW\*(C`fork ()\*(C'\fR was detected (usually because |
3559 | Fork watchers are called when a \f(CW\*(C`fork ()\*(C'\fR was detected (usually because |
3200 | whoever is a good citizen cared to tell libev about it by calling |
3560 | whoever is a good citizen cared to tell libev about it by calling |
3201 | \&\f(CW\*(C`ev_default_fork\*(C'\fR or \f(CW\*(C`ev_loop_fork\*(C'\fR). The invocation is done before the |
3561 | \&\f(CW\*(C`ev_loop_fork\*(C'\fR). The invocation is done before the event loop blocks next |
3202 | event loop blocks next and before \f(CW\*(C`ev_check\*(C'\fR watchers are being called, |
3562 | and before \f(CW\*(C`ev_check\*(C'\fR watchers are being called, and only in the child |
3203 | and only in the child after the fork. If whoever good citizen calling |
3563 | after the fork. If whoever good citizen calling \f(CW\*(C`ev_default_fork\*(C'\fR cheats |
3204 | \&\f(CW\*(C`ev_default_fork\*(C'\fR cheats and calls it in the wrong process, the fork |
3564 | and calls it in the wrong process, the fork handlers will be invoked, too, |
3205 | handlers will be invoked, too, of course. |
3565 | of course. |
3206 | .PP |
3566 | .PP |
3207 | \fIThe special problem of life after fork \- how is it possible?\fR |
3567 | \fIThe special problem of life after fork \- how is it possible?\fR |
3208 | .IX Subsection "The special problem of life after fork - how is it possible?" |
3568 | .IX Subsection "The special problem of life after fork - how is it possible?" |
3209 | .PP |
3569 | .PP |
3210 | Most uses of \f(CW\*(C`fork()\*(C'\fR consist of forking, then some simple calls to set |
3570 | Most uses of \f(CW\*(C`fork ()\*(C'\fR consist of forking, then some simple calls to set |
3211 | up/change the process environment, followed by a call to \f(CW\*(C`exec()\*(C'\fR. This |
3571 | up/change the process environment, followed by a call to \f(CW\*(C`exec()\*(C'\fR. This |
3212 | sequence should be handled by libev without any problems. |
3572 | sequence should be handled by libev without any problems. |
3213 | .PP |
3573 | .PP |
3214 | This changes when the application actually wants to do event handling |
3574 | This changes when the application actually wants to do event handling |
3215 | in the child, or both parent in child, in effect \*(L"continuing\*(R" after the |
3575 | in the child, or both parent in child, in effect \*(L"continuing\*(R" after the |
… | |
… | |
3284 | \& atexit (program_exits); |
3644 | \& atexit (program_exits); |
3285 | .Ve |
3645 | .Ve |
3286 | .ie n .SS """ev_async"" \- how to wake up an event loop" |
3646 | .ie n .SS """ev_async"" \- how to wake up an event loop" |
3287 | .el .SS "\f(CWev_async\fP \- how to wake up an event loop" |
3647 | .el .SS "\f(CWev_async\fP \- how to wake up an event loop" |
3288 | .IX Subsection "ev_async - how to wake up an event loop" |
3648 | .IX Subsection "ev_async - how to wake up an event loop" |
3289 | In general, you cannot use an \f(CW\*(C`ev_run\*(C'\fR from multiple threads or other |
3649 | In general, you cannot use an \f(CW\*(C`ev_loop\*(C'\fR from multiple threads or other |
3290 | asynchronous sources such as signal handlers (as opposed to multiple event |
3650 | asynchronous sources such as signal handlers (as opposed to multiple event |
3291 | loops \- those are of course safe to use in different threads). |
3651 | loops \- those are of course safe to use in different threads). |
3292 | .PP |
3652 | .PP |
3293 | Sometimes, however, you need to wake up an event loop you do not control, |
3653 | Sometimes, however, you need to wake up an event loop you do not control, |
3294 | for example because it belongs to another thread. This is what \f(CW\*(C`ev_async\*(C'\fR |
3654 | for example because it belongs to another thread. This is what \f(CW\*(C`ev_async\*(C'\fR |
… | |
… | |
3296 | it by calling \f(CW\*(C`ev_async_send\*(C'\fR, which is thread\- and signal safe. |
3656 | it by calling \f(CW\*(C`ev_async_send\*(C'\fR, which is thread\- and signal safe. |
3297 | .PP |
3657 | .PP |
3298 | This functionality is very similar to \f(CW\*(C`ev_signal\*(C'\fR watchers, as signals, |
3658 | This functionality is very similar to \f(CW\*(C`ev_signal\*(C'\fR watchers, as signals, |
3299 | too, are asynchronous in nature, and signals, too, will be compressed |
3659 | too, are asynchronous in nature, and signals, too, will be compressed |
3300 | (i.e. the number of callback invocations may be less than the number of |
3660 | (i.e. the number of callback invocations may be less than the number of |
3301 | \&\f(CW\*(C`ev_async_sent\*(C'\fR calls). |
3661 | \&\f(CW\*(C`ev_async_send\*(C'\fR calls). In fact, you could use signal watchers as a kind |
3302 | .PP |
3662 | of \*(L"global async watchers\*(R" by using a watcher on an otherwise unused |
3303 | Unlike \f(CW\*(C`ev_signal\*(C'\fR watchers, \f(CW\*(C`ev_async\*(C'\fR works with any event loop, not |
3663 | signal, and \f(CW\*(C`ev_feed_signal\*(C'\fR to signal this watcher from another thread, |
3304 | just the default loop. |
3664 | even without knowing which loop owns the signal. |
3305 | .PP |
3665 | .PP |
3306 | \fIQueueing\fR |
3666 | \fIQueueing\fR |
3307 | .IX Subsection "Queueing" |
3667 | .IX Subsection "Queueing" |
3308 | .PP |
3668 | .PP |
3309 | \&\f(CW\*(C`ev_async\*(C'\fR does not support queueing of data in any way. The reason |
3669 | \&\f(CW\*(C`ev_async\*(C'\fR does not support queueing of data in any way. The reason |
… | |
… | |
3396 | kind. There is a \f(CW\*(C`ev_async_set\*(C'\fR macro, but using it is utterly pointless, |
3756 | kind. There is a \f(CW\*(C`ev_async_set\*(C'\fR macro, but using it is utterly pointless, |
3397 | trust me. |
3757 | trust me. |
3398 | .IP "ev_async_send (loop, ev_async *)" 4 |
3758 | .IP "ev_async_send (loop, ev_async *)" 4 |
3399 | .IX Item "ev_async_send (loop, ev_async *)" |
3759 | .IX Item "ev_async_send (loop, ev_async *)" |
3400 | Sends/signals/activates the given \f(CW\*(C`ev_async\*(C'\fR watcher, that is, feeds |
3760 | Sends/signals/activates the given \f(CW\*(C`ev_async\*(C'\fR watcher, that is, feeds |
3401 | an \f(CW\*(C`EV_ASYNC\*(C'\fR event on the watcher into the event loop. Unlike |
3761 | an \f(CW\*(C`EV_ASYNC\*(C'\fR event on the watcher into the event loop, and instantly |
|
|
3762 | returns. |
|
|
3763 | .Sp |
3402 | \&\f(CW\*(C`ev_feed_event\*(C'\fR, this call is safe to do from other threads, signal or |
3764 | Unlike \f(CW\*(C`ev_feed_event\*(C'\fR, this call is safe to do from other threads, |
3403 | similar contexts (see the discussion of \f(CW\*(C`EV_ATOMIC_T\*(C'\fR in the embedding |
3765 | signal or similar contexts (see the discussion of \f(CW\*(C`EV_ATOMIC_T\*(C'\fR in the |
3404 | section below on what exactly this means). |
3766 | embedding section below on what exactly this means). |
3405 | .Sp |
3767 | .Sp |
3406 | Note that, as with other watchers in libev, multiple events might get |
3768 | Note that, as with other watchers in libev, multiple events might get |
3407 | compressed into a single callback invocation (another way to look at this |
3769 | compressed into a single callback invocation (another way to look at |
3408 | is that \f(CW\*(C`ev_async\*(C'\fR watchers are level-triggered, set on \f(CW\*(C`ev_async_send\*(C'\fR, |
3770 | this is that \f(CW\*(C`ev_async\*(C'\fR watchers are level-triggered: they are set on |
3409 | reset when the event loop detects that). |
3771 | \&\f(CW\*(C`ev_async_send\*(C'\fR, reset when the event loop detects that). |
3410 | .Sp |
3772 | .Sp |
3411 | This call incurs the overhead of a system call only once per event loop |
3773 | This call incurs the overhead of at most one extra system call per event |
3412 | iteration, so while the overhead might be noticeable, it doesn't apply to |
3774 | loop iteration, if the event loop is blocked, and no syscall at all if |
3413 | repeated calls to \f(CW\*(C`ev_async_send\*(C'\fR for the same event loop. |
3775 | the event loop (or your program) is processing events. That means that |
|
|
3776 | repeated calls are basically free (there is no need to avoid calls for |
|
|
3777 | performance reasons) and that the overhead becomes smaller (typically |
|
|
3778 | zero) under load. |
3414 | .IP "bool = ev_async_pending (ev_async *)" 4 |
3779 | .IP "bool = ev_async_pending (ev_async *)" 4 |
3415 | .IX Item "bool = ev_async_pending (ev_async *)" |
3780 | .IX Item "bool = ev_async_pending (ev_async *)" |
3416 | Returns a non-zero value when \f(CW\*(C`ev_async_send\*(C'\fR has been called on the |
3781 | Returns a non-zero value when \f(CW\*(C`ev_async_send\*(C'\fR has been called on the |
3417 | watcher but the event has not yet been processed (or even noted) by the |
3782 | watcher but the event has not yet been processed (or even noted) by the |
3418 | event loop. |
3783 | event loop. |
… | |
… | |
3427 | is a time window between the event loop checking and resetting the async |
3792 | is a time window between the event loop checking and resetting the async |
3428 | notification, and the callback being invoked. |
3793 | notification, and the callback being invoked. |
3429 | .SH "OTHER FUNCTIONS" |
3794 | .SH "OTHER FUNCTIONS" |
3430 | .IX Header "OTHER FUNCTIONS" |
3795 | .IX Header "OTHER FUNCTIONS" |
3431 | There are some other functions of possible interest. Described. Here. Now. |
3796 | There are some other functions of possible interest. Described. Here. Now. |
3432 | .IP "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" 4 |
3797 | .IP "ev_once (loop, int fd, int events, ev_tstamp timeout, callback, arg)" 4 |
3433 | .IX Item "ev_once (loop, int fd, int events, ev_tstamp timeout, callback)" |
3798 | .IX Item "ev_once (loop, int fd, int events, ev_tstamp timeout, callback, arg)" |
3434 | This function combines a simple timer and an I/O watcher, calls your |
3799 | This function combines a simple timer and an I/O watcher, calls your |
3435 | callback on whichever event happens first and automatically stops both |
3800 | callback on whichever event happens first and automatically stops both |
3436 | watchers. This is useful if you want to wait for a single event on an fd |
3801 | watchers. This is useful if you want to wait for a single event on an fd |
3437 | or timeout without having to allocate/configure/start/stop/free one or |
3802 | or timeout without having to allocate/configure/start/stop/free one or |
3438 | more watchers yourself. |
3803 | more watchers yourself. |
… | |
… | |
3450 | \&\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 |
3815 | \&\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 |
3451 | value passed to \f(CW\*(C`ev_once\*(C'\fR. Note that it is possible to receive \fIboth\fR |
3816 | value passed to \f(CW\*(C`ev_once\*(C'\fR. Note that it is possible to receive \fIboth\fR |
3452 | a timeout and an io event at the same time \- you probably should give io |
3817 | a timeout and an io event at the same time \- you probably should give io |
3453 | events precedence. |
3818 | events precedence. |
3454 | .Sp |
3819 | .Sp |
3455 | Example: wait up to ten seconds for data to appear on \s-1STDIN_FILENO\s0. |
3820 | Example: wait up to ten seconds for data to appear on \s-1STDIN_FILENO.\s0 |
3456 | .Sp |
3821 | .Sp |
3457 | .Vb 7 |
3822 | .Vb 7 |
3458 | \& static void stdin_ready (int revents, void *arg) |
3823 | \& static void stdin_ready (int revents, void *arg) |
3459 | \& { |
3824 | \& { |
3460 | \& if (revents & EV_READ) |
3825 | \& if (revents & EV_READ) |
… | |
… | |
3466 | \& ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
3831 | \& ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
3467 | .Ve |
3832 | .Ve |
3468 | .IP "ev_feed_fd_event (loop, int fd, int revents)" 4 |
3833 | .IP "ev_feed_fd_event (loop, int fd, int revents)" 4 |
3469 | .IX Item "ev_feed_fd_event (loop, int fd, int revents)" |
3834 | .IX Item "ev_feed_fd_event (loop, int fd, int revents)" |
3470 | Feed an event on the given fd, as if a file descriptor backend detected |
3835 | Feed an event on the given fd, as if a file descriptor backend detected |
3471 | the given events it. |
3836 | the given events. |
3472 | .IP "ev_feed_signal_event (loop, int signum)" 4 |
3837 | .IP "ev_feed_signal_event (loop, int signum)" 4 |
3473 | .IX Item "ev_feed_signal_event (loop, int signum)" |
3838 | .IX Item "ev_feed_signal_event (loop, int signum)" |
3474 | Feed an event as if the given signal occurred (\f(CW\*(C`loop\*(C'\fR must be the default |
3839 | Feed an event as if the given signal occurred. See also \f(CW\*(C`ev_feed_signal\*(C'\fR, |
3475 | loop!). |
3840 | which is async-safe. |
|
|
3841 | .SH "COMMON OR USEFUL IDIOMS (OR BOTH)" |
|
|
3842 | .IX Header "COMMON OR USEFUL IDIOMS (OR BOTH)" |
|
|
3843 | This section explains some common idioms that are not immediately |
|
|
3844 | obvious. Note that examples are sprinkled over the whole manual, and this |
|
|
3845 | section only contains stuff that wouldn't fit anywhere else. |
|
|
3846 | .SS "\s-1ASSOCIATING CUSTOM DATA WITH A WATCHER\s0" |
|
|
3847 | .IX Subsection "ASSOCIATING CUSTOM DATA WITH A WATCHER" |
|
|
3848 | Each watcher has, by default, a \f(CW\*(C`void *data\*(C'\fR member that you can read |
|
|
3849 | or modify at any time: libev will completely ignore it. This can be used |
|
|
3850 | to associate arbitrary data with your watcher. If you need more data and |
|
|
3851 | don't want to allocate memory separately and store a pointer to it in that |
|
|
3852 | data member, you can also \*(L"subclass\*(R" the watcher type and provide your own |
|
|
3853 | data: |
|
|
3854 | .PP |
|
|
3855 | .Vb 7 |
|
|
3856 | \& struct my_io |
|
|
3857 | \& { |
|
|
3858 | \& ev_io io; |
|
|
3859 | \& int otherfd; |
|
|
3860 | \& void *somedata; |
|
|
3861 | \& struct whatever *mostinteresting; |
|
|
3862 | \& }; |
|
|
3863 | \& |
|
|
3864 | \& ... |
|
|
3865 | \& struct my_io w; |
|
|
3866 | \& ev_io_init (&w.io, my_cb, fd, EV_READ); |
|
|
3867 | .Ve |
|
|
3868 | .PP |
|
|
3869 | And since your callback will be called with a pointer to the watcher, you |
|
|
3870 | can cast it back to your own type: |
|
|
3871 | .PP |
|
|
3872 | .Vb 5 |
|
|
3873 | \& static void my_cb (struct ev_loop *loop, ev_io *w_, int revents) |
|
|
3874 | \& { |
|
|
3875 | \& struct my_io *w = (struct my_io *)w_; |
|
|
3876 | \& ... |
|
|
3877 | \& } |
|
|
3878 | .Ve |
|
|
3879 | .PP |
|
|
3880 | More interesting and less C\-conformant ways of casting your callback |
|
|
3881 | function type instead have been omitted. |
|
|
3882 | .SS "\s-1BUILDING YOUR OWN COMPOSITE WATCHERS\s0" |
|
|
3883 | .IX Subsection "BUILDING YOUR OWN COMPOSITE WATCHERS" |
|
|
3884 | Another common scenario is to use some data structure with multiple |
|
|
3885 | embedded watchers, in effect creating your own watcher that combines |
|
|
3886 | multiple libev event sources into one \*(L"super-watcher\*(R": |
|
|
3887 | .PP |
|
|
3888 | .Vb 6 |
|
|
3889 | \& struct my_biggy |
|
|
3890 | \& { |
|
|
3891 | \& int some_data; |
|
|
3892 | \& ev_timer t1; |
|
|
3893 | \& ev_timer t2; |
|
|
3894 | \& } |
|
|
3895 | .Ve |
|
|
3896 | .PP |
|
|
3897 | In this case getting the pointer to \f(CW\*(C`my_biggy\*(C'\fR is a bit more |
|
|
3898 | complicated: Either you store the address of your \f(CW\*(C`my_biggy\*(C'\fR struct in |
|
|
3899 | the \f(CW\*(C`data\*(C'\fR member of the watcher (for woozies or \*(C+ coders), or you need |
|
|
3900 | to use some pointer arithmetic using \f(CW\*(C`offsetof\*(C'\fR inside your watchers (for |
|
|
3901 | real programmers): |
|
|
3902 | .PP |
|
|
3903 | .Vb 1 |
|
|
3904 | \& #include <stddef.h> |
|
|
3905 | \& |
|
|
3906 | \& static void |
|
|
3907 | \& t1_cb (EV_P_ ev_timer *w, int revents) |
|
|
3908 | \& { |
|
|
3909 | \& struct my_biggy big = (struct my_biggy *) |
|
|
3910 | \& (((char *)w) \- offsetof (struct my_biggy, t1)); |
|
|
3911 | \& } |
|
|
3912 | \& |
|
|
3913 | \& static void |
|
|
3914 | \& t2_cb (EV_P_ ev_timer *w, int revents) |
|
|
3915 | \& { |
|
|
3916 | \& struct my_biggy big = (struct my_biggy *) |
|
|
3917 | \& (((char *)w) \- offsetof (struct my_biggy, t2)); |
|
|
3918 | \& } |
|
|
3919 | .Ve |
|
|
3920 | .SS "\s-1AVOIDING FINISHING BEFORE RETURNING\s0" |
|
|
3921 | .IX Subsection "AVOIDING FINISHING BEFORE RETURNING" |
|
|
3922 | Often you have structures like this in event-based programs: |
|
|
3923 | .PP |
|
|
3924 | .Vb 4 |
|
|
3925 | \& callback () |
|
|
3926 | \& { |
|
|
3927 | \& free (request); |
|
|
3928 | \& } |
|
|
3929 | \& |
|
|
3930 | \& request = start_new_request (..., callback); |
|
|
3931 | .Ve |
|
|
3932 | .PP |
|
|
3933 | The intent is to start some \*(L"lengthy\*(R" operation. The \f(CW\*(C`request\*(C'\fR could be |
|
|
3934 | used to cancel the operation, or do other things with it. |
|
|
3935 | .PP |
|
|
3936 | It's not uncommon to have code paths in \f(CW\*(C`start_new_request\*(C'\fR that |
|
|
3937 | immediately invoke the callback, for example, to report errors. Or you add |
|
|
3938 | some caching layer that finds that it can skip the lengthy aspects of the |
|
|
3939 | operation and simply invoke the callback with the result. |
|
|
3940 | .PP |
|
|
3941 | The problem here is that this will happen \fIbefore\fR \f(CW\*(C`start_new_request\*(C'\fR |
|
|
3942 | has returned, so \f(CW\*(C`request\*(C'\fR is not set. |
|
|
3943 | .PP |
|
|
3944 | Even if you pass the request by some safer means to the callback, you |
|
|
3945 | might want to do something to the request after starting it, such as |
|
|
3946 | canceling it, which probably isn't working so well when the callback has |
|
|
3947 | already been invoked. |
|
|
3948 | .PP |
|
|
3949 | A common way around all these issues is to make sure that |
|
|
3950 | \&\f(CW\*(C`start_new_request\*(C'\fR \fIalways\fR returns before the callback is invoked. If |
|
|
3951 | \&\f(CW\*(C`start_new_request\*(C'\fR immediately knows the result, it can artificially |
|
|
3952 | delay invoking the callback by using a \f(CW\*(C`prepare\*(C'\fR or \f(CW\*(C`idle\*(C'\fR watcher for |
|
|
3953 | example, or more sneakily, by reusing an existing (stopped) watcher and |
|
|
3954 | pushing it into the pending queue: |
|
|
3955 | .PP |
|
|
3956 | .Vb 2 |
|
|
3957 | \& ev_set_cb (watcher, callback); |
|
|
3958 | \& ev_feed_event (EV_A_ watcher, 0); |
|
|
3959 | .Ve |
|
|
3960 | .PP |
|
|
3961 | This way, \f(CW\*(C`start_new_request\*(C'\fR can safely return before the callback is |
|
|
3962 | invoked, while not delaying callback invocation too much. |
|
|
3963 | .SS "\s-1MODEL/NESTED EVENT LOOP INVOCATIONS AND EXIT CONDITIONS\s0" |
|
|
3964 | .IX Subsection "MODEL/NESTED EVENT LOOP INVOCATIONS AND EXIT CONDITIONS" |
|
|
3965 | Often (especially in \s-1GUI\s0 toolkits) there are places where you have |
|
|
3966 | \&\fImodal\fR interaction, which is most easily implemented by recursively |
|
|
3967 | invoking \f(CW\*(C`ev_run\*(C'\fR. |
|
|
3968 | .PP |
|
|
3969 | This brings the problem of exiting \- a callback might want to finish the |
|
|
3970 | main \f(CW\*(C`ev_run\*(C'\fR call, but not the nested one (e.g. user clicked \*(L"Quit\*(R", but |
|
|
3971 | a modal \*(L"Are you sure?\*(R" dialog is still waiting), or just the nested one |
|
|
3972 | and not the main one (e.g. user clocked \*(L"Ok\*(R" in a modal dialog), or some |
|
|
3973 | other combination: In these cases, a simple \f(CW\*(C`ev_break\*(C'\fR will not work. |
|
|
3974 | .PP |
|
|
3975 | The solution is to maintain \*(L"break this loop\*(R" variable for each \f(CW\*(C`ev_run\*(C'\fR |
|
|
3976 | invocation, and use a loop around \f(CW\*(C`ev_run\*(C'\fR until the condition is |
|
|
3977 | triggered, using \f(CW\*(C`EVRUN_ONCE\*(C'\fR: |
|
|
3978 | .PP |
|
|
3979 | .Vb 2 |
|
|
3980 | \& // main loop |
|
|
3981 | \& int exit_main_loop = 0; |
|
|
3982 | \& |
|
|
3983 | \& while (!exit_main_loop) |
|
|
3984 | \& ev_run (EV_DEFAULT_ EVRUN_ONCE); |
|
|
3985 | \& |
|
|
3986 | \& // in a modal watcher |
|
|
3987 | \& int exit_nested_loop = 0; |
|
|
3988 | \& |
|
|
3989 | \& while (!exit_nested_loop) |
|
|
3990 | \& ev_run (EV_A_ EVRUN_ONCE); |
|
|
3991 | .Ve |
|
|
3992 | .PP |
|
|
3993 | To exit from any of these loops, just set the corresponding exit variable: |
|
|
3994 | .PP |
|
|
3995 | .Vb 2 |
|
|
3996 | \& // exit modal loop |
|
|
3997 | \& exit_nested_loop = 1; |
|
|
3998 | \& |
|
|
3999 | \& // exit main program, after modal loop is finished |
|
|
4000 | \& exit_main_loop = 1; |
|
|
4001 | \& |
|
|
4002 | \& // exit both |
|
|
4003 | \& exit_main_loop = exit_nested_loop = 1; |
|
|
4004 | .Ve |
|
|
4005 | .SS "\s-1THREAD LOCKING EXAMPLE\s0" |
|
|
4006 | .IX Subsection "THREAD LOCKING EXAMPLE" |
|
|
4007 | Here is a fictitious example of how to run an event loop in a different |
|
|
4008 | thread from where callbacks are being invoked and watchers are |
|
|
4009 | created/added/removed. |
|
|
4010 | .PP |
|
|
4011 | For a real-world example, see the \f(CW\*(C`EV::Loop::Async\*(C'\fR perl module, |
|
|
4012 | which uses exactly this technique (which is suited for many high-level |
|
|
4013 | languages). |
|
|
4014 | .PP |
|
|
4015 | The example uses a pthread mutex to protect the loop data, a condition |
|
|
4016 | variable to wait for callback invocations, an async watcher to notify the |
|
|
4017 | event loop thread and an unspecified mechanism to wake up the main thread. |
|
|
4018 | .PP |
|
|
4019 | First, you need to associate some data with the event loop: |
|
|
4020 | .PP |
|
|
4021 | .Vb 6 |
|
|
4022 | \& typedef struct { |
|
|
4023 | \& pthread_mutex_t lock; /* global loop lock */ |
|
|
4024 | \& pthread_t tid; |
|
|
4025 | \& pthread_cond_t invoke_cv; |
|
|
4026 | \& ev_async async_w; |
|
|
4027 | \& } userdata; |
|
|
4028 | \& |
|
|
4029 | \& void prepare_loop (EV_P) |
|
|
4030 | \& { |
|
|
4031 | \& // for simplicity, we use a static userdata struct. |
|
|
4032 | \& static userdata u; |
|
|
4033 | \& |
|
|
4034 | \& ev_async_init (&u.async_w, async_cb); |
|
|
4035 | \& ev_async_start (EV_A_ &u.async_w); |
|
|
4036 | \& |
|
|
4037 | \& pthread_mutex_init (&u.lock, 0); |
|
|
4038 | \& pthread_cond_init (&u.invoke_cv, 0); |
|
|
4039 | \& |
|
|
4040 | \& // now associate this with the loop |
|
|
4041 | \& ev_set_userdata (EV_A_ &u); |
|
|
4042 | \& ev_set_invoke_pending_cb (EV_A_ l_invoke); |
|
|
4043 | \& ev_set_loop_release_cb (EV_A_ l_release, l_acquire); |
|
|
4044 | \& |
|
|
4045 | \& // then create the thread running ev_run |
|
|
4046 | \& pthread_create (&u.tid, 0, l_run, EV_A); |
|
|
4047 | \& } |
|
|
4048 | .Ve |
|
|
4049 | .PP |
|
|
4050 | The callback for the \f(CW\*(C`ev_async\*(C'\fR watcher does nothing: the watcher is used |
|
|
4051 | solely to wake up the event loop so it takes notice of any new watchers |
|
|
4052 | that might have been added: |
|
|
4053 | .PP |
|
|
4054 | .Vb 5 |
|
|
4055 | \& static void |
|
|
4056 | \& async_cb (EV_P_ ev_async *w, int revents) |
|
|
4057 | \& { |
|
|
4058 | \& // just used for the side effects |
|
|
4059 | \& } |
|
|
4060 | .Ve |
|
|
4061 | .PP |
|
|
4062 | The \f(CW\*(C`l_release\*(C'\fR and \f(CW\*(C`l_acquire\*(C'\fR callbacks simply unlock/lock the mutex |
|
|
4063 | protecting the loop data, respectively. |
|
|
4064 | .PP |
|
|
4065 | .Vb 6 |
|
|
4066 | \& static void |
|
|
4067 | \& l_release (EV_P) |
|
|
4068 | \& { |
|
|
4069 | \& userdata *u = ev_userdata (EV_A); |
|
|
4070 | \& pthread_mutex_unlock (&u\->lock); |
|
|
4071 | \& } |
|
|
4072 | \& |
|
|
4073 | \& static void |
|
|
4074 | \& l_acquire (EV_P) |
|
|
4075 | \& { |
|
|
4076 | \& userdata *u = ev_userdata (EV_A); |
|
|
4077 | \& pthread_mutex_lock (&u\->lock); |
|
|
4078 | \& } |
|
|
4079 | .Ve |
|
|
4080 | .PP |
|
|
4081 | The event loop thread first acquires the mutex, and then jumps straight |
|
|
4082 | into \f(CW\*(C`ev_run\*(C'\fR: |
|
|
4083 | .PP |
|
|
4084 | .Vb 4 |
|
|
4085 | \& void * |
|
|
4086 | \& l_run (void *thr_arg) |
|
|
4087 | \& { |
|
|
4088 | \& struct ev_loop *loop = (struct ev_loop *)thr_arg; |
|
|
4089 | \& |
|
|
4090 | \& l_acquire (EV_A); |
|
|
4091 | \& pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0); |
|
|
4092 | \& ev_run (EV_A_ 0); |
|
|
4093 | \& l_release (EV_A); |
|
|
4094 | \& |
|
|
4095 | \& return 0; |
|
|
4096 | \& } |
|
|
4097 | .Ve |
|
|
4098 | .PP |
|
|
4099 | Instead of invoking all pending watchers, the \f(CW\*(C`l_invoke\*(C'\fR callback will |
|
|
4100 | signal the main thread via some unspecified mechanism (signals? pipe |
|
|
4101 | writes? \f(CW\*(C`Async::Interrupt\*(C'\fR?) and then waits until all pending watchers |
|
|
4102 | have been called (in a while loop because a) spurious wakeups are possible |
|
|
4103 | and b) skipping inter-thread-communication when there are no pending |
|
|
4104 | watchers is very beneficial): |
|
|
4105 | .PP |
|
|
4106 | .Vb 4 |
|
|
4107 | \& static void |
|
|
4108 | \& l_invoke (EV_P) |
|
|
4109 | \& { |
|
|
4110 | \& userdata *u = ev_userdata (EV_A); |
|
|
4111 | \& |
|
|
4112 | \& while (ev_pending_count (EV_A)) |
|
|
4113 | \& { |
|
|
4114 | \& wake_up_other_thread_in_some_magic_or_not_so_magic_way (); |
|
|
4115 | \& pthread_cond_wait (&u\->invoke_cv, &u\->lock); |
|
|
4116 | \& } |
|
|
4117 | \& } |
|
|
4118 | .Ve |
|
|
4119 | .PP |
|
|
4120 | Now, whenever the main thread gets told to invoke pending watchers, it |
|
|
4121 | will grab the lock, call \f(CW\*(C`ev_invoke_pending\*(C'\fR and then signal the loop |
|
|
4122 | thread to continue: |
|
|
4123 | .PP |
|
|
4124 | .Vb 4 |
|
|
4125 | \& static void |
|
|
4126 | \& real_invoke_pending (EV_P) |
|
|
4127 | \& { |
|
|
4128 | \& userdata *u = ev_userdata (EV_A); |
|
|
4129 | \& |
|
|
4130 | \& pthread_mutex_lock (&u\->lock); |
|
|
4131 | \& ev_invoke_pending (EV_A); |
|
|
4132 | \& pthread_cond_signal (&u\->invoke_cv); |
|
|
4133 | \& pthread_mutex_unlock (&u\->lock); |
|
|
4134 | \& } |
|
|
4135 | .Ve |
|
|
4136 | .PP |
|
|
4137 | Whenever you want to start/stop a watcher or do other modifications to an |
|
|
4138 | event loop, you will now have to lock: |
|
|
4139 | .PP |
|
|
4140 | .Vb 2 |
|
|
4141 | \& ev_timer timeout_watcher; |
|
|
4142 | \& userdata *u = ev_userdata (EV_A); |
|
|
4143 | \& |
|
|
4144 | \& ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.); |
|
|
4145 | \& |
|
|
4146 | \& pthread_mutex_lock (&u\->lock); |
|
|
4147 | \& ev_timer_start (EV_A_ &timeout_watcher); |
|
|
4148 | \& ev_async_send (EV_A_ &u\->async_w); |
|
|
4149 | \& pthread_mutex_unlock (&u\->lock); |
|
|
4150 | .Ve |
|
|
4151 | .PP |
|
|
4152 | Note that sending the \f(CW\*(C`ev_async\*(C'\fR watcher is required because otherwise |
|
|
4153 | an event loop currently blocking in the kernel will have no knowledge |
|
|
4154 | about the newly added timer. By waking up the loop it will pick up any new |
|
|
4155 | watchers in the next event loop iteration. |
|
|
4156 | .SS "\s-1THREADS, COROUTINES, CONTINUATIONS, QUEUES... INSTEAD OF CALLBACKS\s0" |
|
|
4157 | .IX Subsection "THREADS, COROUTINES, CONTINUATIONS, QUEUES... INSTEAD OF CALLBACKS" |
|
|
4158 | While the overhead of a callback that e.g. schedules a thread is small, it |
|
|
4159 | is still an overhead. If you embed libev, and your main usage is with some |
|
|
4160 | kind of threads or coroutines, you might want to customise libev so that |
|
|
4161 | doesn't need callbacks anymore. |
|
|
4162 | .PP |
|
|
4163 | Imagine you have coroutines that you can switch to using a function |
|
|
4164 | \&\f(CW\*(C`switch_to (coro)\*(C'\fR, that libev runs in a coroutine called \f(CW\*(C`libev_coro\*(C'\fR |
|
|
4165 | and that due to some magic, the currently active coroutine is stored in a |
|
|
4166 | global called \f(CW\*(C`current_coro\*(C'\fR. Then you can build your own \*(L"wait for libev |
|
|
4167 | event\*(R" primitive by changing \f(CW\*(C`EV_CB_DECLARE\*(C'\fR and \f(CW\*(C`EV_CB_INVOKE\*(C'\fR (note |
|
|
4168 | the differing \f(CW\*(C`;\*(C'\fR conventions): |
|
|
4169 | .PP |
|
|
4170 | .Vb 2 |
|
|
4171 | \& #define EV_CB_DECLARE(type) struct my_coro *cb; |
|
|
4172 | \& #define EV_CB_INVOKE(watcher) switch_to ((watcher)\->cb) |
|
|
4173 | .Ve |
|
|
4174 | .PP |
|
|
4175 | That means instead of having a C callback function, you store the |
|
|
4176 | coroutine to switch to in each watcher, and instead of having libev call |
|
|
4177 | your callback, you instead have it switch to that coroutine. |
|
|
4178 | .PP |
|
|
4179 | A coroutine might now wait for an event with a function called |
|
|
4180 | \&\f(CW\*(C`wait_for_event\*(C'\fR. (the watcher needs to be started, as always, but it doesn't |
|
|
4181 | matter when, or whether the watcher is active or not when this function is |
|
|
4182 | called): |
|
|
4183 | .PP |
|
|
4184 | .Vb 6 |
|
|
4185 | \& void |
|
|
4186 | \& wait_for_event (ev_watcher *w) |
|
|
4187 | \& { |
|
|
4188 | \& ev_set_cb (w, current_coro); |
|
|
4189 | \& switch_to (libev_coro); |
|
|
4190 | \& } |
|
|
4191 | .Ve |
|
|
4192 | .PP |
|
|
4193 | That basically suspends the coroutine inside \f(CW\*(C`wait_for_event\*(C'\fR and |
|
|
4194 | continues the libev coroutine, which, when appropriate, switches back to |
|
|
4195 | this or any other coroutine. |
|
|
4196 | .PP |
|
|
4197 | You can do similar tricks if you have, say, threads with an event queue \- |
|
|
4198 | instead of storing a coroutine, you store the queue object and instead of |
|
|
4199 | switching to a coroutine, you push the watcher onto the queue and notify |
|
|
4200 | any waiters. |
|
|
4201 | .PP |
|
|
4202 | To embed libev, see \*(L"\s-1EMBEDDING\*(R"\s0, but in short, it's easiest to create two |
|
|
4203 | files, \fImy_ev.h\fR and \fImy_ev.c\fR that include the respective libev files: |
|
|
4204 | .PP |
|
|
4205 | .Vb 4 |
|
|
4206 | \& // my_ev.h |
|
|
4207 | \& #define EV_CB_DECLARE(type) struct my_coro *cb; |
|
|
4208 | \& #define EV_CB_INVOKE(watcher) switch_to ((watcher)\->cb) |
|
|
4209 | \& #include "../libev/ev.h" |
|
|
4210 | \& |
|
|
4211 | \& // my_ev.c |
|
|
4212 | \& #define EV_H "my_ev.h" |
|
|
4213 | \& #include "../libev/ev.c" |
|
|
4214 | .Ve |
|
|
4215 | .PP |
|
|
4216 | And then use \fImy_ev.h\fR when you would normally use \fIev.h\fR, and compile |
|
|
4217 | \&\fImy_ev.c\fR into your project. When properly specifying include paths, you |
|
|
4218 | can even use \fIev.h\fR as header file name directly. |
3476 | .SH "LIBEVENT EMULATION" |
4219 | .SH "LIBEVENT EMULATION" |
3477 | .IX Header "LIBEVENT EMULATION" |
4220 | .IX Header "LIBEVENT EMULATION" |
3478 | Libev offers a compatibility emulation layer for libevent. It cannot |
4221 | Libev offers a compatibility emulation layer for libevent. It cannot |
3479 | emulate the internals of libevent, so here are some usage hints: |
4222 | emulate the internals of libevent, so here are some usage hints: |
|
|
4223 | .IP "\(bu" 4 |
|
|
4224 | Only the libevent\-1.4.1\-beta \s-1API\s0 is being emulated. |
|
|
4225 | .Sp |
|
|
4226 | This was the newest libevent version available when libev was implemented, |
|
|
4227 | and is still mostly unchanged in 2010. |
3480 | .IP "\(bu" 4 |
4228 | .IP "\(bu" 4 |
3481 | Use it by including <event.h>, as usual. |
4229 | Use it by including <event.h>, as usual. |
3482 | .IP "\(bu" 4 |
4230 | .IP "\(bu" 4 |
3483 | The following members are fully supported: ev_base, ev_callback, |
4231 | The following members are fully supported: ev_base, ev_callback, |
3484 | ev_arg, ev_fd, ev_res, ev_events. |
4232 | ev_arg, ev_fd, ev_res, ev_events. |
… | |
… | |
3490 | Priorities are not currently supported. Initialising priorities |
4238 | Priorities are not currently supported. Initialising priorities |
3491 | will fail and all watchers will have the same priority, even though there |
4239 | will fail and all watchers will have the same priority, even though there |
3492 | is an ev_pri field. |
4240 | is an ev_pri field. |
3493 | .IP "\(bu" 4 |
4241 | .IP "\(bu" 4 |
3494 | In libevent, the last base created gets the signals, in libev, the |
4242 | In libevent, the last base created gets the signals, in libev, the |
3495 | first base created (== the default loop) gets the signals. |
4243 | base that registered the signal gets the signals. |
3496 | .IP "\(bu" 4 |
4244 | .IP "\(bu" 4 |
3497 | Other members are not supported. |
4245 | Other members are not supported. |
3498 | .IP "\(bu" 4 |
4246 | .IP "\(bu" 4 |
3499 | The libev emulation is \fInot\fR \s-1ABI\s0 compatible to libevent, you need |
4247 | The libev emulation is \fInot\fR \s-1ABI\s0 compatible to libevent, you need |
3500 | to use the libev header file and library. |
4248 | to use the libev header file and library. |
3501 | .SH "\*(C+ SUPPORT" |
4249 | .SH "\*(C+ SUPPORT" |
3502 | .IX Header " SUPPORT" |
4250 | .IX Header " SUPPORT" |
|
|
4251 | .SS "C \s-1API\s0" |
|
|
4252 | .IX Subsection "C API" |
|
|
4253 | The normal C \s-1API\s0 should work fine when used from \*(C+: both ev.h and the |
|
|
4254 | libev sources can be compiled as \*(C+. Therefore, code that uses the C \s-1API\s0 |
|
|
4255 | will work fine. |
|
|
4256 | .PP |
|
|
4257 | Proper exception specifications might have to be added to callbacks passed |
|
|
4258 | to libev: exceptions may be thrown only from watcher callbacks, all other |
|
|
4259 | callbacks (allocator, syserr, loop acquire/release and periodic reschedule |
|
|
4260 | callbacks) must not throw exceptions, and might need a \f(CW\*(C`noexcept\*(C'\fR |
|
|
4261 | specification. If you have code that needs to be compiled as both C and |
|
|
4262 | \&\*(C+ you can use the \f(CW\*(C`EV_NOEXCEPT\*(C'\fR macro for this: |
|
|
4263 | .PP |
|
|
4264 | .Vb 6 |
|
|
4265 | \& static void |
|
|
4266 | \& fatal_error (const char *msg) EV_NOEXCEPT |
|
|
4267 | \& { |
|
|
4268 | \& perror (msg); |
|
|
4269 | \& abort (); |
|
|
4270 | \& } |
|
|
4271 | \& |
|
|
4272 | \& ... |
|
|
4273 | \& ev_set_syserr_cb (fatal_error); |
|
|
4274 | .Ve |
|
|
4275 | .PP |
|
|
4276 | The only \s-1API\s0 functions that can currently throw exceptions are \f(CW\*(C`ev_run\*(C'\fR, |
|
|
4277 | \&\f(CW\*(C`ev_invoke\*(C'\fR, \f(CW\*(C`ev_invoke_pending\*(C'\fR and \f(CW\*(C`ev_loop_destroy\*(C'\fR (the latter |
|
|
4278 | because it runs cleanup watchers). |
|
|
4279 | .PP |
|
|
4280 | Throwing exceptions in watcher callbacks is only supported if libev itself |
|
|
4281 | is compiled with a \*(C+ compiler or your C and \*(C+ environments allow |
|
|
4282 | throwing exceptions through C libraries (most do). |
|
|
4283 | .SS "\*(C+ \s-1API\s0" |
|
|
4284 | .IX Subsection " API" |
3503 | Libev comes with some simplistic wrapper classes for \*(C+ that mainly allow |
4285 | Libev comes with some simplistic wrapper classes for \*(C+ that mainly allow |
3504 | you to use some convenience methods to start/stop watchers and also change |
4286 | you to use some convenience methods to start/stop watchers and also change |
3505 | the callback model to a model using method callbacks on objects. |
4287 | the callback model to a model using method callbacks on objects. |
3506 | .PP |
4288 | .PP |
3507 | To use it, |
4289 | To use it, |
… | |
… | |
3518 | Care has been taken to keep the overhead low. The only data member the \*(C+ |
4300 | Care has been taken to keep the overhead low. The only data member the \*(C+ |
3519 | classes add (compared to plain C\-style watchers) is the event loop pointer |
4301 | classes add (compared to plain C\-style watchers) is the event loop pointer |
3520 | that the watcher is associated with (or no additional members at all if |
4302 | that the watcher is associated with (or no additional members at all if |
3521 | you disable \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR when embedding libev). |
4303 | you disable \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR when embedding libev). |
3522 | .PP |
4304 | .PP |
3523 | Currently, functions, and static and non-static member functions can be |
4305 | Currently, functions, static and non-static member functions and classes |
3524 | used as callbacks. Other types should be easy to add as long as they only |
4306 | with \f(CW\*(C`operator ()\*(C'\fR can be used as callbacks. Other types should be easy |
3525 | need one additional pointer for context. If you need support for other |
4307 | to add as long as they only need one additional pointer for context. If |
3526 | types of functors please contact the author (preferably after implementing |
4308 | you need support for other types of functors please contact the author |
3527 | it). |
4309 | (preferably after implementing it). |
|
|
4310 | .PP |
|
|
4311 | For all this to work, your \*(C+ compiler either has to use the same calling |
|
|
4312 | conventions as your C compiler (for static member functions), or you have |
|
|
4313 | to embed libev and compile libev itself as \*(C+. |
3528 | .PP |
4314 | .PP |
3529 | Here is a list of things available in the \f(CW\*(C`ev\*(C'\fR namespace: |
4315 | Here is a list of things available in the \f(CW\*(C`ev\*(C'\fR namespace: |
3530 | .ie n .IP """ev::READ"", ""ev::WRITE"" etc." 4 |
4316 | .ie n .IP """ev::READ"", ""ev::WRITE"" etc." 4 |
3531 | .el .IP "\f(CWev::READ\fR, \f(CWev::WRITE\fR etc." 4 |
4317 | .el .IP "\f(CWev::READ\fR, \f(CWev::WRITE\fR etc." 4 |
3532 | .IX Item "ev::READ, ev::WRITE etc." |
4318 | .IX Item "ev::READ, ev::WRITE etc." |
… | |
… | |
3540 | .el .IP "\f(CWev::io\fR, \f(CWev::timer\fR, \f(CWev::periodic\fR, \f(CWev::idle\fR, \f(CWev::sig\fR etc." 4 |
4326 | .el .IP "\f(CWev::io\fR, \f(CWev::timer\fR, \f(CWev::periodic\fR, \f(CWev::idle\fR, \f(CWev::sig\fR etc." 4 |
3541 | .IX Item "ev::io, ev::timer, ev::periodic, ev::idle, ev::sig etc." |
4327 | .IX Item "ev::io, ev::timer, ev::periodic, ev::idle, ev::sig etc." |
3542 | For each \f(CW\*(C`ev_TYPE\*(C'\fR watcher in \fIev.h\fR there is a corresponding class of |
4328 | For each \f(CW\*(C`ev_TYPE\*(C'\fR watcher in \fIev.h\fR there is a corresponding class of |
3543 | the same name in the \f(CW\*(C`ev\*(C'\fR namespace, with the exception of \f(CW\*(C`ev_signal\*(C'\fR |
4329 | the same name in the \f(CW\*(C`ev\*(C'\fR namespace, with the exception of \f(CW\*(C`ev_signal\*(C'\fR |
3544 | which is called \f(CW\*(C`ev::sig\*(C'\fR to avoid clashes with the \f(CW\*(C`signal\*(C'\fR macro |
4330 | which is called \f(CW\*(C`ev::sig\*(C'\fR to avoid clashes with the \f(CW\*(C`signal\*(C'\fR macro |
3545 | defines by many implementations. |
4331 | defined by many implementations. |
3546 | .Sp |
4332 | .Sp |
3547 | All of those classes have these methods: |
4333 | All of those classes have these methods: |
3548 | .RS 4 |
4334 | .RS 4 |
3549 | .IP "ev::TYPE::TYPE ()" 4 |
4335 | .IP "ev::TYPE::TYPE ()" 4 |
3550 | .IX Item "ev::TYPE::TYPE ()" |
4336 | .IX Item "ev::TYPE::TYPE ()" |
… | |
… | |
3613 | \& void operator() (ev::io &w, int revents) |
4399 | \& void operator() (ev::io &w, int revents) |
3614 | \& { |
4400 | \& { |
3615 | \& ... |
4401 | \& ... |
3616 | \& } |
4402 | \& } |
3617 | \& } |
4403 | \& } |
3618 | \& |
4404 | \& |
3619 | \& myfunctor f; |
4405 | \& myfunctor f; |
3620 | \& |
4406 | \& |
3621 | \& ev::io w; |
4407 | \& ev::io w; |
3622 | \& w.set (&f); |
4408 | \& w.set (&f); |
3623 | .Ve |
4409 | .Ve |
… | |
… | |
3641 | .IX Item "w->set (loop)" |
4427 | .IX Item "w->set (loop)" |
3642 | Associates a different \f(CW\*(C`struct ev_loop\*(C'\fR with this watcher. You can only |
4428 | Associates a different \f(CW\*(C`struct ev_loop\*(C'\fR with this watcher. You can only |
3643 | do this when the watcher is inactive (and not pending either). |
4429 | do this when the watcher is inactive (and not pending either). |
3644 | .IP "w\->set ([arguments])" 4 |
4430 | .IP "w\->set ([arguments])" 4 |
3645 | .IX Item "w->set ([arguments])" |
4431 | .IX Item "w->set ([arguments])" |
3646 | Basically the same as \f(CW\*(C`ev_TYPE_set\*(C'\fR, with the same arguments. Either this |
4432 | Basically the same as \f(CW\*(C`ev_TYPE_set\*(C'\fR (except for \f(CW\*(C`ev::embed\*(C'\fR watchers>), |
3647 | method or a suitable start method must be called at least once. Unlike the |
4433 | with the same arguments. Either this method or a suitable start method |
3648 | C counterpart, an active watcher gets automatically stopped and restarted |
4434 | must be called at least once. Unlike the C counterpart, an active watcher |
3649 | when reconfiguring it with this method. |
4435 | gets automatically stopped and restarted when reconfiguring it with this |
|
|
4436 | method. |
|
|
4437 | .Sp |
|
|
4438 | For \f(CW\*(C`ev::embed\*(C'\fR watchers this method is called \f(CW\*(C`set_embed\*(C'\fR, to avoid |
|
|
4439 | clashing with the \f(CW\*(C`set (loop)\*(C'\fR method. |
|
|
4440 | .Sp |
|
|
4441 | For \f(CW\*(C`ev::io\*(C'\fR watchers there is an additional \f(CW\*(C`set\*(C'\fR method that acepts a |
|
|
4442 | new event mask only, and internally calls \f(CW\*(C`ev_io_modify\*(C'\fR. |
3650 | .IP "w\->start ()" 4 |
4443 | .IP "w\->start ()" 4 |
3651 | .IX Item "w->start ()" |
4444 | .IX Item "w->start ()" |
3652 | Starts the watcher. Note that there is no \f(CW\*(C`loop\*(C'\fR argument, as the |
4445 | Starts the watcher. Note that there is no \f(CW\*(C`loop\*(C'\fR argument, as the |
3653 | constructor already stores the event loop. |
4446 | constructor already stores the event loop. |
3654 | .IP "w\->start ([arguments])" 4 |
4447 | .IP "w\->start ([arguments])" 4 |
… | |
… | |
3681 | .PP |
4474 | .PP |
3682 | .Vb 5 |
4475 | .Vb 5 |
3683 | \& class myclass |
4476 | \& class myclass |
3684 | \& { |
4477 | \& { |
3685 | \& ev::io io ; void io_cb (ev::io &w, int revents); |
4478 | \& ev::io io ; void io_cb (ev::io &w, int revents); |
3686 | \& ev::io2 io2 ; void io2_cb (ev::io &w, int revents); |
4479 | \& ev::io io2 ; void io2_cb (ev::io &w, int revents); |
3687 | \& ev::idle idle; void idle_cb (ev::idle &w, int revents); |
4480 | \& ev::idle idle; void idle_cb (ev::idle &w, int revents); |
3688 | \& |
4481 | \& |
3689 | \& myclass (int fd) |
4482 | \& myclass (int fd) |
3690 | \& { |
4483 | \& { |
3691 | \& io .set <myclass, &myclass::io_cb > (this); |
4484 | \& io .set <myclass, &myclass::io_cb > (this); |
… | |
… | |
3712 | there are additional modules that implement libev-compatible interfaces |
4505 | there are additional modules that implement libev-compatible interfaces |
3713 | to \f(CW\*(C`libadns\*(C'\fR (\f(CW\*(C`EV::ADNS\*(C'\fR, but \f(CW\*(C`AnyEvent::DNS\*(C'\fR is preferred nowadays), |
4506 | to \f(CW\*(C`libadns\*(C'\fR (\f(CW\*(C`EV::ADNS\*(C'\fR, but \f(CW\*(C`AnyEvent::DNS\*(C'\fR is preferred nowadays), |
3714 | \&\f(CW\*(C`Net::SNMP\*(C'\fR (\f(CW\*(C`Net::SNMP::EV\*(C'\fR) and the \f(CW\*(C`libglib\*(C'\fR event core (\f(CW\*(C`Glib::EV\*(C'\fR |
4507 | \&\f(CW\*(C`Net::SNMP\*(C'\fR (\f(CW\*(C`Net::SNMP::EV\*(C'\fR) and the \f(CW\*(C`libglib\*(C'\fR event core (\f(CW\*(C`Glib::EV\*(C'\fR |
3715 | and \f(CW\*(C`EV::Glib\*(C'\fR). |
4508 | and \f(CW\*(C`EV::Glib\*(C'\fR). |
3716 | .Sp |
4509 | .Sp |
3717 | It can be found and installed via \s-1CPAN\s0, its homepage is at |
4510 | It can be found and installed via \s-1CPAN,\s0 its homepage is at |
3718 | <http://software.schmorp.de/pkg/EV>. |
4511 | <http://software.schmorp.de/pkg/EV>. |
3719 | .IP "Python" 4 |
4512 | .IP "Python" 4 |
3720 | .IX Item "Python" |
4513 | .IX Item "Python" |
3721 | Python bindings can be found at <http://code.google.com/p/pyev/>. It |
4514 | Python bindings can be found at <http://code.google.com/p/pyev/>. It |
3722 | seems to be quite complete and well-documented. |
4515 | seems to be quite complete and well-documented. |
… | |
… | |
3734 | A haskell binding to libev is available at |
4527 | A haskell binding to libev is available at |
3735 | <http://hackage.haskell.org/cgi\-bin/hackage\-scripts/package/hlibev>. |
4528 | <http://hackage.haskell.org/cgi\-bin/hackage\-scripts/package/hlibev>. |
3736 | .IP "D" 4 |
4529 | .IP "D" 4 |
3737 | .IX Item "D" |
4530 | .IX Item "D" |
3738 | Leandro Lucarella has written a D language binding (\fIev.d\fR) for libev, to |
4531 | Leandro Lucarella has written a D language binding (\fIev.d\fR) for libev, to |
3739 | be found at <http://proj.llucax.com.ar/wiki/evd>. |
4532 | be found at <http://www.llucax.com.ar/proj/ev.d/index.html>. |
3740 | .IP "Ocaml" 4 |
4533 | .IP "Ocaml" 4 |
3741 | .IX Item "Ocaml" |
4534 | .IX Item "Ocaml" |
3742 | Erkki Seppala has written Ocaml bindings for libev, to be found at |
4535 | Erkki Seppala has written Ocaml bindings for libev, to be found at |
3743 | <http://modeemi.cs.tut.fi/~flux/software/ocaml\-ev/>. |
4536 | <http://modeemi.cs.tut.fi/~flux/software/ocaml\-ev/>. |
3744 | .IP "Lua" 4 |
4537 | .IP "Lua" 4 |
3745 | .IX Item "Lua" |
4538 | .IX Item "Lua" |
3746 | Brian Maher has written a partial interface to libev for lua (at the |
4539 | Brian Maher has written a partial interface to libev for lua (at the |
3747 | time of this writing, only \f(CW\*(C`ev_io\*(C'\fR and \f(CW\*(C`ev_timer\*(C'\fR), to be found at |
4540 | time of this writing, only \f(CW\*(C`ev_io\*(C'\fR and \f(CW\*(C`ev_timer\*(C'\fR), to be found at |
3748 | <http://github.com/brimworks/lua\-ev>. |
4541 | <http://github.com/brimworks/lua\-ev>. |
|
|
4542 | .IP "Javascript" 4 |
|
|
4543 | .IX Item "Javascript" |
|
|
4544 | Node.js (<http://nodejs.org>) uses libev as the underlying event library. |
|
|
4545 | .IP "Others" 4 |
|
|
4546 | .IX Item "Others" |
|
|
4547 | There are others, and I stopped counting. |
3749 | .SH "MACRO MAGIC" |
4548 | .SH "MACRO MAGIC" |
3750 | .IX Header "MACRO MAGIC" |
4549 | .IX Header "MACRO MAGIC" |
3751 | Libev can be compiled with a variety of options, the most fundamental |
4550 | Libev can be compiled with a variety of options, the most fundamental |
3752 | of which is \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. This option determines whether (most) |
4551 | of which is \f(CW\*(C`EV_MULTIPLICITY\*(C'\fR. This option determines whether (most) |
3753 | functions and callbacks have an initial \f(CW\*(C`struct ev_loop *\*(C'\fR argument. |
4552 | functions and callbacks have an initial \f(CW\*(C`struct ev_loop *\*(C'\fR argument. |
… | |
… | |
3788 | suitable for use with \f(CW\*(C`EV_A\*(C'\fR. |
4587 | suitable for use with \f(CW\*(C`EV_A\*(C'\fR. |
3789 | .ie n .IP """EV_DEFAULT"", ""EV_DEFAULT_""" 4 |
4588 | .ie n .IP """EV_DEFAULT"", ""EV_DEFAULT_""" 4 |
3790 | .el .IP "\f(CWEV_DEFAULT\fR, \f(CWEV_DEFAULT_\fR" 4 |
4589 | .el .IP "\f(CWEV_DEFAULT\fR, \f(CWEV_DEFAULT_\fR" 4 |
3791 | .IX Item "EV_DEFAULT, EV_DEFAULT_" |
4590 | .IX Item "EV_DEFAULT, EV_DEFAULT_" |
3792 | Similar to the other two macros, this gives you the value of the default |
4591 | Similar to the other two macros, this gives you the value of the default |
3793 | loop, if multiple loops are supported (\*(L"ev loop default\*(R"). |
4592 | loop, if multiple loops are supported (\*(L"ev loop default\*(R"). The default loop |
|
|
4593 | will be initialised if it isn't already initialised. |
|
|
4594 | .Sp |
|
|
4595 | For non-multiplicity builds, these macros do nothing, so you always have |
|
|
4596 | to initialise the loop somewhere. |
3794 | .ie n .IP """EV_DEFAULT_UC"", ""EV_DEFAULT_UC_""" 4 |
4597 | .ie n .IP """EV_DEFAULT_UC"", ""EV_DEFAULT_UC_""" 4 |
3795 | .el .IP "\f(CWEV_DEFAULT_UC\fR, \f(CWEV_DEFAULT_UC_\fR" 4 |
4598 | .el .IP "\f(CWEV_DEFAULT_UC\fR, \f(CWEV_DEFAULT_UC_\fR" 4 |
3796 | .IX Item "EV_DEFAULT_UC, EV_DEFAULT_UC_" |
4599 | .IX Item "EV_DEFAULT_UC, EV_DEFAULT_UC_" |
3797 | Usage identical to \f(CW\*(C`EV_DEFAULT\*(C'\fR and \f(CW\*(C`EV_DEFAULT_\*(C'\fR, but requires that the |
4600 | Usage identical to \f(CW\*(C`EV_DEFAULT\*(C'\fR and \f(CW\*(C`EV_DEFAULT_\*(C'\fR, but requires that the |
3798 | default loop has been initialised (\f(CW\*(C`UC\*(C'\fR == unchecked). Their behaviour |
4601 | default loop has been initialised (\f(CW\*(C`UC\*(C'\fR == unchecked). Their behaviour |
… | |
… | |
3832 | .SS "\s-1FILESETS\s0" |
4635 | .SS "\s-1FILESETS\s0" |
3833 | .IX Subsection "FILESETS" |
4636 | .IX Subsection "FILESETS" |
3834 | Depending on what features you need you need to include one or more sets of files |
4637 | Depending on what features you need you need to include one or more sets of files |
3835 | in your application. |
4638 | in your application. |
3836 | .PP |
4639 | .PP |
3837 | \fI\s-1CORE\s0 \s-1EVENT\s0 \s-1LOOP\s0\fR |
4640 | \fI\s-1CORE EVENT LOOP\s0\fR |
3838 | .IX Subsection "CORE EVENT LOOP" |
4641 | .IX Subsection "CORE EVENT LOOP" |
3839 | .PP |
4642 | .PP |
3840 | To include only the libev core (all the \f(CW\*(C`ev_*\*(C'\fR functions), with manual |
4643 | To include only the libev core (all the \f(CW\*(C`ev_*\*(C'\fR functions), with manual |
3841 | configuration (no autoconf): |
4644 | configuration (no autoconf): |
3842 | .PP |
4645 | .PP |
… | |
… | |
3869 | \& ev_vars.h |
4672 | \& ev_vars.h |
3870 | \& ev_wrap.h |
4673 | \& ev_wrap.h |
3871 | \& |
4674 | \& |
3872 | \& ev_win32.c required on win32 platforms only |
4675 | \& ev_win32.c required on win32 platforms only |
3873 | \& |
4676 | \& |
3874 | \& ev_select.c only when select backend is enabled (which is enabled by default) |
4677 | \& ev_select.c only when select backend is enabled |
3875 | \& ev_poll.c only when poll backend is enabled (disabled by default) |
4678 | \& ev_poll.c only when poll backend is enabled |
3876 | \& ev_epoll.c only when the epoll backend is enabled (disabled by default) |
4679 | \& ev_epoll.c only when the epoll backend is enabled |
|
|
4680 | \& ev_linuxaio.c only when the linux aio backend is enabled |
|
|
4681 | \& ev_iouring.c only when the linux io_uring backend is enabled |
3877 | \& ev_kqueue.c only when the kqueue backend is enabled (disabled by default) |
4682 | \& ev_kqueue.c only when the kqueue backend is enabled |
3878 | \& ev_port.c only when the solaris port backend is enabled (disabled by default) |
4683 | \& ev_port.c only when the solaris port backend is enabled |
3879 | .Ve |
4684 | .Ve |
3880 | .PP |
4685 | .PP |
3881 | \&\fIev.c\fR includes the backend files directly when enabled, so you only need |
4686 | \&\fIev.c\fR includes the backend files directly when enabled, so you only need |
3882 | to compile this single file. |
4687 | to compile this single file. |
3883 | .PP |
4688 | .PP |
3884 | \fI\s-1LIBEVENT\s0 \s-1COMPATIBILITY\s0 \s-1API\s0\fR |
4689 | \fI\s-1LIBEVENT COMPATIBILITY API\s0\fR |
3885 | .IX Subsection "LIBEVENT COMPATIBILITY API" |
4690 | .IX Subsection "LIBEVENT COMPATIBILITY API" |
3886 | .PP |
4691 | .PP |
3887 | To include the libevent compatibility \s-1API\s0, also include: |
4692 | To include the libevent compatibility \s-1API,\s0 also include: |
3888 | .PP |
4693 | .PP |
3889 | .Vb 1 |
4694 | .Vb 1 |
3890 | \& #include "event.c" |
4695 | \& #include "event.c" |
3891 | .Ve |
4696 | .Ve |
3892 | .PP |
4697 | .PP |
… | |
… | |
3894 | .PP |
4699 | .PP |
3895 | .Vb 1 |
4700 | .Vb 1 |
3896 | \& #include "event.h" |
4701 | \& #include "event.h" |
3897 | .Ve |
4702 | .Ve |
3898 | .PP |
4703 | .PP |
3899 | in the files that want to use the libevent \s-1API\s0. This also includes \fIev.h\fR. |
4704 | in the files that want to use the libevent \s-1API.\s0 This also includes \fIev.h\fR. |
3900 | .PP |
4705 | .PP |
3901 | You need the following additional files for this: |
4706 | You need the following additional files for this: |
3902 | .PP |
4707 | .PP |
3903 | .Vb 2 |
4708 | .Vb 2 |
3904 | \& event.h |
4709 | \& event.h |
3905 | \& event.c |
4710 | \& event.c |
3906 | .Ve |
4711 | .Ve |
3907 | .PP |
4712 | .PP |
3908 | \fI\s-1AUTOCONF\s0 \s-1SUPPORT\s0\fR |
4713 | \fI\s-1AUTOCONF SUPPORT\s0\fR |
3909 | .IX Subsection "AUTOCONF SUPPORT" |
4714 | .IX Subsection "AUTOCONF SUPPORT" |
3910 | .PP |
4715 | .PP |
3911 | Instead of using \f(CW\*(C`EV_STANDALONE=1\*(C'\fR and providing your configuration in |
4716 | Instead of using \f(CW\*(C`EV_STANDALONE=1\*(C'\fR and providing your configuration in |
3912 | whatever way you want, you can also \f(CW\*(C`m4_include([libev.m4])\*(C'\fR in your |
4717 | whatever way you want, you can also \f(CW\*(C`m4_include([libev.m4])\*(C'\fR in your |
3913 | \&\fIconfigure.ac\fR and leave \f(CW\*(C`EV_STANDALONE\*(C'\fR undefined. \fIev.c\fR will then |
4718 | \&\fIconfigure.ac\fR and leave \f(CW\*(C`EV_STANDALONE\*(C'\fR undefined. \fIev.c\fR will then |
… | |
… | |
3916 | For this of course you need the m4 file: |
4721 | For this of course you need the m4 file: |
3917 | .PP |
4722 | .PP |
3918 | .Vb 1 |
4723 | .Vb 1 |
3919 | \& libev.m4 |
4724 | \& libev.m4 |
3920 | .Ve |
4725 | .Ve |
3921 | .SS "\s-1PREPROCESSOR\s0 \s-1SYMBOLS/MACROS\s0" |
4726 | .SS "\s-1PREPROCESSOR SYMBOLS/MACROS\s0" |
3922 | .IX Subsection "PREPROCESSOR SYMBOLS/MACROS" |
4727 | .IX Subsection "PREPROCESSOR SYMBOLS/MACROS" |
3923 | Libev can be configured via a variety of preprocessor symbols you have to |
4728 | Libev can be configured via a variety of preprocessor symbols you have to |
3924 | define before including (or compiling) any of its files. The default in |
4729 | define before including (or compiling) any of its files. The default in |
3925 | the absence of autoconf is documented for every option. |
4730 | the absence of autoconf is documented for every option. |
3926 | .PP |
4731 | .PP |
3927 | Symbols marked with \*(L"(h)\*(R" do not change the \s-1ABI\s0, and can have different |
4732 | Symbols marked with \*(L"(h)\*(R" do not change the \s-1ABI,\s0 and can have different |
3928 | values when compiling libev vs. including \fIev.h\fR, so it is permissible |
4733 | values when compiling libev vs. including \fIev.h\fR, so it is permissible |
3929 | to redefine them before including \fIev.h\fR without breaking compatibility |
4734 | to redefine them before including \fIev.h\fR without breaking compatibility |
3930 | to a compiled library. All other symbols change the \s-1ABI\s0, which means all |
4735 | to a compiled library. All other symbols change the \s-1ABI,\s0 which means all |
3931 | users of libev and the libev code itself must be compiled with compatible |
4736 | users of libev and the libev code itself must be compiled with compatible |
3932 | settings. |
4737 | settings. |
3933 | .IP "\s-1EV_COMPAT3\s0 (h)" 4 |
4738 | .IP "\s-1EV_COMPAT3\s0 (h)" 4 |
3934 | .IX Item "EV_COMPAT3 (h)" |
4739 | .IX Item "EV_COMPAT3 (h)" |
3935 | Backwards compatibility is a major concern for libev. This is why this |
4740 | Backwards compatibility is a major concern for libev. This is why this |
… | |
… | |
3953 | supported). It will also not define any of the structs usually found in |
4758 | supported). It will also not define any of the structs usually found in |
3954 | \&\fIevent.h\fR that are not directly supported by the libev core alone. |
4759 | \&\fIevent.h\fR that are not directly supported by the libev core alone. |
3955 | .Sp |
4760 | .Sp |
3956 | In standalone mode, libev will still try to automatically deduce the |
4761 | In standalone mode, libev will still try to automatically deduce the |
3957 | configuration, but has to be more conservative. |
4762 | configuration, but has to be more conservative. |
|
|
4763 | .IP "\s-1EV_USE_FLOOR\s0" 4 |
|
|
4764 | .IX Item "EV_USE_FLOOR" |
|
|
4765 | If defined to be \f(CW1\fR, libev will use the \f(CW\*(C`floor ()\*(C'\fR function for its |
|
|
4766 | periodic reschedule calculations, otherwise libev will fall back on a |
|
|
4767 | portable (slower) implementation. If you enable this, you usually have to |
|
|
4768 | link against libm or something equivalent. Enabling this when the \f(CW\*(C`floor\*(C'\fR |
|
|
4769 | function is not available will fail, so the safe default is to not enable |
|
|
4770 | this. |
3958 | .IP "\s-1EV_USE_MONOTONIC\s0" 4 |
4771 | .IP "\s-1EV_USE_MONOTONIC\s0" 4 |
3959 | .IX Item "EV_USE_MONOTONIC" |
4772 | .IX Item "EV_USE_MONOTONIC" |
3960 | If defined to be \f(CW1\fR, libev will try to detect the availability of the |
4773 | If defined to be \f(CW1\fR, libev will try to detect the availability of the |
3961 | monotonic clock option at both compile time and runtime. Otherwise no |
4774 | monotonic clock option at both compile time and runtime. Otherwise no |
3962 | use of the monotonic clock option will be attempted. If you enable this, |
4775 | use of the monotonic clock option will be attempted. If you enable this, |
… | |
… | |
3986 | higher, as it simplifies linking (no need for \f(CW\*(C`\-lrt\*(C'\fR). |
4799 | higher, as it simplifies linking (no need for \f(CW\*(C`\-lrt\*(C'\fR). |
3987 | .IP "\s-1EV_USE_NANOSLEEP\s0" 4 |
4800 | .IP "\s-1EV_USE_NANOSLEEP\s0" 4 |
3988 | .IX Item "EV_USE_NANOSLEEP" |
4801 | .IX Item "EV_USE_NANOSLEEP" |
3989 | If defined to be \f(CW1\fR, libev will assume that \f(CW\*(C`nanosleep ()\*(C'\fR is available |
4802 | If defined to be \f(CW1\fR, libev will assume that \f(CW\*(C`nanosleep ()\*(C'\fR is available |
3990 | and will use it for delays. Otherwise it will use \f(CW\*(C`select ()\*(C'\fR. |
4803 | and will use it for delays. Otherwise it will use \f(CW\*(C`select ()\*(C'\fR. |
|
|
4804 | .IP "\s-1EV_USE_EVENTFD\s0" 4 |
|
|
4805 | .IX Item "EV_USE_EVENTFD" |
|
|
4806 | If defined to be \f(CW1\fR, then libev will assume that \f(CW\*(C`eventfd ()\*(C'\fR is |
|
|
4807 | available and will probe for kernel support at runtime. This will improve |
|
|
4808 | \&\f(CW\*(C`ev_signal\*(C'\fR and \f(CW\*(C`ev_async\*(C'\fR performance and reduce resource consumption. |
|
|
4809 | If undefined, it will be enabled if the headers indicate GNU/Linux + Glibc |
|
|
4810 | 2.7 or newer, otherwise disabled. |
|
|
4811 | .IP "\s-1EV_USE_SIGNALFD\s0" 4 |
|
|
4812 | .IX Item "EV_USE_SIGNALFD" |
|
|
4813 | If defined to be \f(CW1\fR, then libev will assume that \f(CW\*(C`signalfd ()\*(C'\fR is |
|
|
4814 | available and will probe for kernel support at runtime. This enables |
|
|
4815 | the use of \s-1EVFLAG_SIGNALFD\s0 for faster and simpler signal handling. If |
|
|
4816 | undefined, it will be enabled if the headers indicate GNU/Linux + Glibc |
|
|
4817 | 2.7 or newer, otherwise disabled. |
|
|
4818 | .IP "\s-1EV_USE_TIMERFD\s0" 4 |
|
|
4819 | .IX Item "EV_USE_TIMERFD" |
|
|
4820 | If defined to be \f(CW1\fR, then libev will assume that \f(CW\*(C`timerfd ()\*(C'\fR is |
|
|
4821 | available and will probe for kernel support at runtime. This allows |
|
|
4822 | libev to detect time jumps accurately. If undefined, it will be enabled |
|
|
4823 | if the headers indicate GNU/Linux + Glibc 2.8 or newer and define |
|
|
4824 | \&\f(CW\*(C`TFD_TIMER_CANCEL_ON_SET\*(C'\fR, otherwise disabled. |
3991 | .IP "\s-1EV_USE_EVENTFD\s0" 4 |
4825 | .IP "\s-1EV_USE_EVENTFD\s0" 4 |
3992 | .IX Item "EV_USE_EVENTFD" |
4826 | .IX Item "EV_USE_EVENTFD" |
3993 | If defined to be \f(CW1\fR, then libev will assume that \f(CW\*(C`eventfd ()\*(C'\fR is |
4827 | If defined to be \f(CW1\fR, then libev will assume that \f(CW\*(C`eventfd ()\*(C'\fR is |
3994 | available and will probe for kernel support at runtime. This will improve |
4828 | available and will probe for kernel support at runtime. This will improve |
3995 | \&\f(CW\*(C`ev_signal\*(C'\fR and \f(CW\*(C`ev_async\*(C'\fR performance and reduce resource consumption. |
4829 | \&\f(CW\*(C`ev_signal\*(C'\fR and \f(CW\*(C`ev_async\*(C'\fR performance and reduce resource consumption. |
… | |
… | |
4036 | .IX Item "EV_WIN32_CLOSE_FD(fd)" |
4870 | .IX Item "EV_WIN32_CLOSE_FD(fd)" |
4037 | If programs implement their own fd to handle mapping on win32, then this |
4871 | If programs implement their own fd to handle mapping on win32, then this |
4038 | macro can be used to override the \f(CW\*(C`close\*(C'\fR function, useful to unregister |
4872 | macro can be used to override the \f(CW\*(C`close\*(C'\fR function, useful to unregister |
4039 | file descriptors again. Note that the replacement function has to close |
4873 | file descriptors again. Note that the replacement function has to close |
4040 | the underlying \s-1OS\s0 handle. |
4874 | the underlying \s-1OS\s0 handle. |
|
|
4875 | .IP "\s-1EV_USE_WSASOCKET\s0" 4 |
|
|
4876 | .IX Item "EV_USE_WSASOCKET" |
|
|
4877 | If defined to be \f(CW1\fR, libev will use \f(CW\*(C`WSASocket\*(C'\fR to create its internal |
|
|
4878 | communication socket, which works better in some environments. Otherwise, |
|
|
4879 | the normal \f(CW\*(C`socket\*(C'\fR function will be used, which works better in other |
|
|
4880 | environments. |
4041 | .IP "\s-1EV_USE_POLL\s0" 4 |
4881 | .IP "\s-1EV_USE_POLL\s0" 4 |
4042 | .IX Item "EV_USE_POLL" |
4882 | .IX Item "EV_USE_POLL" |
4043 | If defined to be \f(CW1\fR, libev will compile in support for the \f(CW\*(C`poll\*(C'\fR(2) |
4883 | If defined to be \f(CW1\fR, libev will compile in support for the \f(CW\*(C`poll\*(C'\fR(2) |
4044 | backend. Otherwise it will be enabled on non\-win32 platforms. It |
4884 | backend. Otherwise it will be enabled on non\-win32 platforms. It |
4045 | takes precedence over select. |
4885 | takes precedence over select. |
… | |
… | |
4048 | If defined to be \f(CW1\fR, libev will compile in support for the Linux |
4888 | If defined to be \f(CW1\fR, libev will compile in support for the Linux |
4049 | \&\f(CW\*(C`epoll\*(C'\fR(7) backend. Its availability will be detected at runtime, |
4889 | \&\f(CW\*(C`epoll\*(C'\fR(7) backend. Its availability will be detected at runtime, |
4050 | otherwise another method will be used as fallback. This is the preferred |
4890 | otherwise another method will be used as fallback. This is the preferred |
4051 | backend for GNU/Linux systems. If undefined, it will be enabled if the |
4891 | backend for GNU/Linux systems. If undefined, it will be enabled if the |
4052 | headers indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled. |
4892 | headers indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled. |
|
|
4893 | .IP "\s-1EV_USE_LINUXAIO\s0" 4 |
|
|
4894 | .IX Item "EV_USE_LINUXAIO" |
|
|
4895 | If defined to be \f(CW1\fR, libev will compile in support for the Linux aio |
|
|
4896 | backend (\f(CW\*(C`EV_USE_EPOLL\*(C'\fR must also be enabled). If undefined, it will be |
|
|
4897 | enabled on linux, otherwise disabled. |
|
|
4898 | .IP "\s-1EV_USE_IOURING\s0" 4 |
|
|
4899 | .IX Item "EV_USE_IOURING" |
|
|
4900 | If defined to be \f(CW1\fR, libev will compile in support for the Linux |
|
|
4901 | io_uring backend (\f(CW\*(C`EV_USE_EPOLL\*(C'\fR must also be enabled). Due to it's |
|
|
4902 | current limitations it has to be requested explicitly. If undefined, it |
|
|
4903 | will be enabled on linux, otherwise disabled. |
4053 | .IP "\s-1EV_USE_KQUEUE\s0" 4 |
4904 | .IP "\s-1EV_USE_KQUEUE\s0" 4 |
4054 | .IX Item "EV_USE_KQUEUE" |
4905 | .IX Item "EV_USE_KQUEUE" |
4055 | If defined to be \f(CW1\fR, libev will compile in support for the \s-1BSD\s0 style |
4906 | If defined to be \f(CW1\fR, libev will compile in support for the \s-1BSD\s0 style |
4056 | \&\f(CW\*(C`kqueue\*(C'\fR(2) backend. Its actual availability will be detected at runtime, |
4907 | \&\f(CW\*(C`kqueue\*(C'\fR(2) backend. Its actual availability will be detected at runtime, |
4057 | otherwise another method will be used as fallback. This is the preferred |
4908 | otherwise another method will be used as fallback. This is the preferred |
… | |
… | |
4074 | .IX Item "EV_USE_INOTIFY" |
4925 | .IX Item "EV_USE_INOTIFY" |
4075 | If defined to be \f(CW1\fR, libev will compile in support for the Linux inotify |
4926 | If defined to be \f(CW1\fR, libev will compile in support for the Linux inotify |
4076 | interface to speed up \f(CW\*(C`ev_stat\*(C'\fR watchers. Its actual availability will |
4927 | interface to speed up \f(CW\*(C`ev_stat\*(C'\fR watchers. Its actual availability will |
4077 | be detected at runtime. If undefined, it will be enabled if the headers |
4928 | be detected at runtime. If undefined, it will be enabled if the headers |
4078 | indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled. |
4929 | indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled. |
|
|
4930 | .IP "\s-1EV_NO_SMP\s0" 4 |
|
|
4931 | .IX Item "EV_NO_SMP" |
|
|
4932 | If defined to be \f(CW1\fR, libev will assume that memory is always coherent |
|
|
4933 | between threads, that is, threads can be used, but threads never run on |
|
|
4934 | different cpus (or different cpu cores). This reduces dependencies |
|
|
4935 | and makes libev faster. |
|
|
4936 | .IP "\s-1EV_NO_THREADS\s0" 4 |
|
|
4937 | .IX Item "EV_NO_THREADS" |
|
|
4938 | If defined to be \f(CW1\fR, libev will assume that it will never be called from |
|
|
4939 | different threads (that includes signal handlers), which is a stronger |
|
|
4940 | assumption than \f(CW\*(C`EV_NO_SMP\*(C'\fR, above. This reduces dependencies and makes |
|
|
4941 | libev faster. |
4079 | .IP "\s-1EV_ATOMIC_T\s0" 4 |
4942 | .IP "\s-1EV_ATOMIC_T\s0" 4 |
4080 | .IX Item "EV_ATOMIC_T" |
4943 | .IX Item "EV_ATOMIC_T" |
4081 | Libev requires an integer type (suitable for storing \f(CW0\fR or \f(CW1\fR) whose |
4944 | Libev requires an integer type (suitable for storing \f(CW0\fR or \f(CW1\fR) whose |
4082 | access is atomic with respect to other threads or signal contexts. No such |
4945 | access is atomic with respect to other threads or signal contexts. No |
4083 | type is easily found in the C language, so you can provide your own type |
4946 | such type is easily found in the C language, so you can provide your own |
4084 | that you know is safe for your purposes. It is used both for signal handler \*(L"locking\*(R" |
4947 | type that you know is safe for your purposes. It is used both for signal |
4085 | as well as for signal and thread safety in \f(CW\*(C`ev_async\*(C'\fR watchers. |
4948 | handler \*(L"locking\*(R" as well as for signal and thread safety in \f(CW\*(C`ev_async\*(C'\fR |
|
|
4949 | watchers. |
4086 | .Sp |
4950 | .Sp |
4087 | In the absence of this define, libev will use \f(CW\*(C`sig_atomic_t volatile\*(C'\fR |
4951 | In the absence of this define, libev will use \f(CW\*(C`sig_atomic_t volatile\*(C'\fR |
4088 | (from \fIsignal.h\fR), which is usually good enough on most platforms. |
4952 | (from \fIsignal.h\fR), which is usually good enough on most platforms. |
4089 | .IP "\s-1EV_H\s0 (h)" 4 |
4953 | .IP "\s-1EV_H\s0 (h)" 4 |
4090 | .IX Item "EV_H (h)" |
4954 | .IX Item "EV_H (h)" |
… | |
… | |
4111 | If undefined or defined to \f(CW1\fR, then all event-loop-specific functions |
4975 | If undefined or defined to \f(CW1\fR, then all event-loop-specific functions |
4112 | will have the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument, and you can create |
4976 | will have the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument, and you can create |
4113 | additional independent event loops. Otherwise there will be no support |
4977 | additional independent event loops. Otherwise there will be no support |
4114 | for multiple event loops and there is no first event loop pointer |
4978 | for multiple event loops and there is no first event loop pointer |
4115 | argument. Instead, all functions act on the single default loop. |
4979 | argument. Instead, all functions act on the single default loop. |
|
|
4980 | .Sp |
|
|
4981 | Note that \f(CW\*(C`EV_DEFAULT\*(C'\fR and \f(CW\*(C`EV_DEFAULT_\*(C'\fR will no longer provide a |
|
|
4982 | default loop when multiplicity is switched off \- you always have to |
|
|
4983 | initialise the loop manually in this case. |
4116 | .IP "\s-1EV_MINPRI\s0" 4 |
4984 | .IP "\s-1EV_MINPRI\s0" 4 |
4117 | .IX Item "EV_MINPRI" |
4985 | .IX Item "EV_MINPRI" |
4118 | .PD 0 |
4986 | .PD 0 |
4119 | .IP "\s-1EV_MAXPRI\s0" 4 |
4987 | .IP "\s-1EV_MAXPRI\s0" 4 |
4120 | .IX Item "EV_MAXPRI" |
4988 | .IX Item "EV_MAXPRI" |
… | |
… | |
4128 | all the priorities, so having many of them (hundreds) uses a lot of space |
4996 | all the priorities, so having many of them (hundreds) uses a lot of space |
4129 | and time, so using the defaults of five priorities (\-2 .. +2) is usually |
4997 | and time, so using the defaults of five priorities (\-2 .. +2) is usually |
4130 | fine. |
4998 | fine. |
4131 | .Sp |
4999 | .Sp |
4132 | If your embedding application does not need any priorities, defining these |
5000 | If your embedding application does not need any priorities, defining these |
4133 | both to \f(CW0\fR will save some memory and \s-1CPU\s0. |
5001 | both to \f(CW0\fR will save some memory and \s-1CPU.\s0 |
4134 | .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 |
5002 | .IP "\s-1EV_PERIODIC_ENABLE, EV_IDLE_ENABLE, EV_EMBED_ENABLE, EV_STAT_ENABLE, EV_PREPARE_ENABLE, EV_CHECK_ENABLE, EV_FORK_ENABLE, EV_SIGNAL_ENABLE, EV_ASYNC_ENABLE, EV_CHILD_ENABLE.\s0" 4 |
4135 | .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." |
5003 | .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." |
4136 | If undefined or defined to be \f(CW1\fR (and the platform supports it), then |
5004 | If undefined or defined to be \f(CW1\fR (and the platform supports it), then |
4137 | the respective watcher type is supported. If defined to be \f(CW0\fR, then it |
5005 | the respective watcher type is supported. If defined to be \f(CW0\fR, then it |
4138 | is not. Disabling watcher types mainly saves code size. |
5006 | is not. Disabling watcher types mainly saves code size. |
4139 | .IP "\s-1EV_FEATURES\s0" 4 |
5007 | .IP "\s-1EV_FEATURES\s0" 4 |
… | |
… | |
4156 | \& #define EV_CHILD_ENABLE 1 |
5024 | \& #define EV_CHILD_ENABLE 1 |
4157 | \& #define EV_ASYNC_ENABLE 1 |
5025 | \& #define EV_ASYNC_ENABLE 1 |
4158 | .Ve |
5026 | .Ve |
4159 | .Sp |
5027 | .Sp |
4160 | The actual value is a bitset, it can be a combination of the following |
5028 | The actual value is a bitset, it can be a combination of the following |
4161 | values: |
5029 | values (by default, all of these are enabled): |
4162 | .RS 4 |
5030 | .RS 4 |
4163 | .ie n .IP "1 \- faster/larger code" 4 |
5031 | .ie n .IP "1 \- faster/larger code" 4 |
4164 | .el .IP "\f(CW1\fR \- faster/larger code" 4 |
5032 | .el .IP "\f(CW1\fR \- faster/larger code" 4 |
4165 | .IX Item "1 - faster/larger code" |
5033 | .IX Item "1 - faster/larger code" |
4166 | Use larger code to speed up some operations. |
5034 | Use larger code to speed up some operations. |
… | |
… | |
4169 | code size by roughly 30% on amd64). |
5037 | code size by roughly 30% on amd64). |
4170 | .Sp |
5038 | .Sp |
4171 | When optimising for size, use of compiler flags such as \f(CW\*(C`\-Os\*(C'\fR with |
5039 | When optimising for size, use of compiler flags such as \f(CW\*(C`\-Os\*(C'\fR with |
4172 | gcc is recommended, as well as \f(CW\*(C`\-DNDEBUG\*(C'\fR, as libev contains a number of |
5040 | gcc is recommended, as well as \f(CW\*(C`\-DNDEBUG\*(C'\fR, as libev contains a number of |
4173 | assertions. |
5041 | assertions. |
|
|
5042 | .Sp |
|
|
5043 | The default is off when \f(CW\*(C`_\|_OPTIMIZE_SIZE_\|_\*(C'\fR is defined by your compiler |
|
|
5044 | (e.g. gcc with \f(CW\*(C`\-Os\*(C'\fR). |
4174 | .ie n .IP "2 \- faster/larger data structures" 4 |
5045 | .ie n .IP "2 \- faster/larger data structures" 4 |
4175 | .el .IP "\f(CW2\fR \- faster/larger data structures" 4 |
5046 | .el .IP "\f(CW2\fR \- faster/larger data structures" 4 |
4176 | .IX Item "2 - faster/larger data structures" |
5047 | .IX Item "2 - faster/larger data structures" |
4177 | Replaces the small 2\-heap for timer management by a faster 4\-heap, larger |
5048 | Replaces the small 2\-heap for timer management by a faster 4\-heap, larger |
4178 | hash table sizes and so on. This will usually further increase code size |
5049 | hash table sizes and so on. This will usually further increase code size |
4179 | and can additionally have an effect on the size of data structures at |
5050 | and can additionally have an effect on the size of data structures at |
4180 | runtime. |
5051 | runtime. |
|
|
5052 | .Sp |
|
|
5053 | The default is off when \f(CW\*(C`_\|_OPTIMIZE_SIZE_\|_\*(C'\fR is defined by your compiler |
|
|
5054 | (e.g. gcc with \f(CW\*(C`\-Os\*(C'\fR). |
4181 | .ie n .IP "4 \- full \s-1API\s0 configuration" 4 |
5055 | .ie n .IP "4 \- full \s-1API\s0 configuration" 4 |
4182 | .el .IP "\f(CW4\fR \- full \s-1API\s0 configuration" 4 |
5056 | .el .IP "\f(CW4\fR \- full \s-1API\s0 configuration" 4 |
4183 | .IX Item "4 - full API configuration" |
5057 | .IX Item "4 - full API configuration" |
4184 | This enables priorities (sets \f(CW\*(C`EV_MAXPRI\*(C'\fR=2 and \f(CW\*(C`EV_MINPRI\*(C'\fR=\-2), and |
5058 | This enables priorities (sets \f(CW\*(C`EV_MAXPRI\*(C'\fR=2 and \f(CW\*(C`EV_MINPRI\*(C'\fR=\-2), and |
4185 | enables multiplicity (\f(CW\*(C`EV_MULTIPLICITY\*(C'\fR=1). |
5059 | enables multiplicity (\f(CW\*(C`EV_MULTIPLICITY\*(C'\fR=1). |
… | |
… | |
4217 | With an intelligent-enough linker (gcc+binutils are intelligent enough |
5091 | With an intelligent-enough linker (gcc+binutils are intelligent enough |
4218 | when you use \f(CW\*(C`\-Wl,\-\-gc\-sections \-ffunction\-sections\*(C'\fR) functions unused by |
5092 | when you use \f(CW\*(C`\-Wl,\-\-gc\-sections \-ffunction\-sections\*(C'\fR) functions unused by |
4219 | your program might be left out as well \- a binary starting a timer and an |
5093 | your program might be left out as well \- a binary starting a timer and an |
4220 | I/O watcher then might come out at only 5Kb. |
5094 | I/O watcher then might come out at only 5Kb. |
4221 | .RE |
5095 | .RE |
|
|
5096 | .IP "\s-1EV_API_STATIC\s0" 4 |
|
|
5097 | .IX Item "EV_API_STATIC" |
|
|
5098 | If this symbol is defined (by default it is not), then all identifiers |
|
|
5099 | will have static linkage. This means that libev will not export any |
|
|
5100 | identifiers, and you cannot link against libev anymore. This can be useful |
|
|
5101 | when you embed libev, only want to use libev functions in a single file, |
|
|
5102 | and do not want its identifiers to be visible. |
|
|
5103 | .Sp |
|
|
5104 | To use this, define \f(CW\*(C`EV_API_STATIC\*(C'\fR and include \fIev.c\fR in the file that |
|
|
5105 | wants to use libev. |
|
|
5106 | .Sp |
|
|
5107 | This option only works when libev is compiled with a C compiler, as \*(C+ |
|
|
5108 | doesn't support the required declaration syntax. |
4222 | .IP "\s-1EV_AVOID_STDIO\s0" 4 |
5109 | .IP "\s-1EV_AVOID_STDIO\s0" 4 |
4223 | .IX Item "EV_AVOID_STDIO" |
5110 | .IX Item "EV_AVOID_STDIO" |
4224 | If this is set to \f(CW1\fR at compiletime, then libev will avoid using stdio |
5111 | If this is set to \f(CW1\fR at compiletime, then libev will avoid using stdio |
4225 | functions (printf, scanf, perror etc.). This will increase the code size |
5112 | functions (printf, scanf, perror etc.). This will increase the code size |
4226 | somewhat, but if your program doesn't otherwise depend on stdio and your |
5113 | somewhat, but if your program doesn't otherwise depend on stdio and your |
… | |
… | |
4278 | called. If set to \f(CW2\fR, then the internal verification code will be |
5165 | called. If set to \f(CW2\fR, then the internal verification code will be |
4279 | called once per loop, which can slow down libev. If set to \f(CW3\fR, then the |
5166 | called once per loop, which can slow down libev. If set to \f(CW3\fR, then the |
4280 | verification code will be called very frequently, which will slow down |
5167 | verification code will be called very frequently, which will slow down |
4281 | libev considerably. |
5168 | libev considerably. |
4282 | .Sp |
5169 | .Sp |
|
|
5170 | Verification errors are reported via C's \f(CW\*(C`assert\*(C'\fR mechanism, so if you |
|
|
5171 | disable that (e.g. by defining \f(CW\*(C`NDEBUG\*(C'\fR) then no errors will be reported. |
|
|
5172 | .Sp |
4283 | The default is \f(CW1\fR, unless \f(CW\*(C`EV_FEATURES\*(C'\fR overrides it, in which case it |
5173 | The default is \f(CW1\fR, unless \f(CW\*(C`EV_FEATURES\*(C'\fR overrides it, in which case it |
4284 | will be \f(CW0\fR. |
5174 | will be \f(CW0\fR. |
4285 | .IP "\s-1EV_COMMON\s0" 4 |
5175 | .IP "\s-1EV_COMMON\s0" 4 |
4286 | .IX Item "EV_COMMON" |
5176 | .IX Item "EV_COMMON" |
4287 | By default, all watchers have a \f(CW\*(C`void *data\*(C'\fR member. By redefining |
5177 | By default, all watchers have a \f(CW\*(C`void *data\*(C'\fR member. By redefining |
… | |
… | |
4308 | and the way callbacks are invoked and set. Must expand to a struct member |
5198 | and the way callbacks are invoked and set. Must expand to a struct member |
4309 | definition and a statement, respectively. See the \fIev.h\fR header file for |
5199 | definition and a statement, respectively. See the \fIev.h\fR header file for |
4310 | their default definitions. One possible use for overriding these is to |
5200 | their default definitions. One possible use for overriding these is to |
4311 | avoid the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument in all cases, or to use |
5201 | avoid the \f(CW\*(C`struct ev_loop *\*(C'\fR as first argument in all cases, or to use |
4312 | method calls instead of plain function calls in \*(C+. |
5202 | method calls instead of plain function calls in \*(C+. |
4313 | .SS "\s-1EXPORTED\s0 \s-1API\s0 \s-1SYMBOLS\s0" |
5203 | .SS "\s-1EXPORTED API SYMBOLS\s0" |
4314 | .IX Subsection "EXPORTED API SYMBOLS" |
5204 | .IX Subsection "EXPORTED API SYMBOLS" |
4315 | If you need to re-export the \s-1API\s0 (e.g. via a \s-1DLL\s0) and you need a list of |
5205 | If you need to re-export the \s-1API\s0 (e.g. via a \s-1DLL\s0) and you need a list of |
4316 | exported symbols, you can use the provided \fISymbol.*\fR files which list |
5206 | exported symbols, you can use the provided \fISymbol.*\fR files which list |
4317 | all public symbols, one per line: |
5207 | all public symbols, one per line: |
4318 | .PP |
5208 | .PP |
… | |
… | |
4370 | .PP |
5260 | .PP |
4371 | .Vb 2 |
5261 | .Vb 2 |
4372 | \& #include "ev_cpp.h" |
5262 | \& #include "ev_cpp.h" |
4373 | \& #include "ev.c" |
5263 | \& #include "ev.c" |
4374 | .Ve |
5264 | .Ve |
4375 | .SH "INTERACTION WITH OTHER PROGRAMS OR LIBRARIES" |
5265 | .SH "INTERACTION WITH OTHER PROGRAMS, LIBRARIES OR THE ENVIRONMENT" |
4376 | .IX Header "INTERACTION WITH OTHER PROGRAMS OR LIBRARIES" |
5266 | .IX Header "INTERACTION WITH OTHER PROGRAMS, LIBRARIES OR THE ENVIRONMENT" |
4377 | .SS "\s-1THREADS\s0 \s-1AND\s0 \s-1COROUTINES\s0" |
5267 | .SS "\s-1THREADS AND COROUTINES\s0" |
4378 | .IX Subsection "THREADS AND COROUTINES" |
5268 | .IX Subsection "THREADS AND COROUTINES" |
4379 | \fI\s-1THREADS\s0\fR |
5269 | \fI\s-1THREADS\s0\fR |
4380 | .IX Subsection "THREADS" |
5270 | .IX Subsection "THREADS" |
4381 | .PP |
5271 | .PP |
4382 | All libev functions are reentrant and thread-safe unless explicitly |
5272 | All libev functions are reentrant and thread-safe unless explicitly |
… | |
… | |
4428 | An example use would be to communicate signals or other events that only |
5318 | An example use would be to communicate signals or other events that only |
4429 | work in the default loop by registering the signal watcher with the |
5319 | work in the default loop by registering the signal watcher with the |
4430 | default loop and triggering an \f(CW\*(C`ev_async\*(C'\fR watcher from the default loop |
5320 | default loop and triggering an \f(CW\*(C`ev_async\*(C'\fR watcher from the default loop |
4431 | watcher callback into the event loop interested in the signal. |
5321 | watcher callback into the event loop interested in the signal. |
4432 | .PP |
5322 | .PP |
4433 | \s-1THREAD\s0 \s-1LOCKING\s0 \s-1EXAMPLE\s0 |
5323 | See also \*(L"\s-1THREAD LOCKING EXAMPLE\*(R"\s0. |
4434 | .IX Subsection "THREAD LOCKING EXAMPLE" |
|
|
4435 | .PP |
|
|
4436 | Here is a fictitious example of how to run an event loop in a different |
|
|
4437 | thread than where callbacks are being invoked and watchers are |
|
|
4438 | created/added/removed. |
|
|
4439 | .PP |
|
|
4440 | For a real-world example, see the \f(CW\*(C`EV::Loop::Async\*(C'\fR perl module, |
|
|
4441 | which uses exactly this technique (which is suited for many high-level |
|
|
4442 | languages). |
|
|
4443 | .PP |
|
|
4444 | The example uses a pthread mutex to protect the loop data, a condition |
|
|
4445 | variable to wait for callback invocations, an async watcher to notify the |
|
|
4446 | event loop thread and an unspecified mechanism to wake up the main thread. |
|
|
4447 | .PP |
|
|
4448 | First, you need to associate some data with the event loop: |
|
|
4449 | .PP |
|
|
4450 | .Vb 6 |
|
|
4451 | \& typedef struct { |
|
|
4452 | \& mutex_t lock; /* global loop lock */ |
|
|
4453 | \& ev_async async_w; |
|
|
4454 | \& thread_t tid; |
|
|
4455 | \& cond_t invoke_cv; |
|
|
4456 | \& } userdata; |
|
|
4457 | \& |
|
|
4458 | \& void prepare_loop (EV_P) |
|
|
4459 | \& { |
|
|
4460 | \& // for simplicity, we use a static userdata struct. |
|
|
4461 | \& static userdata u; |
|
|
4462 | \& |
|
|
4463 | \& ev_async_init (&u\->async_w, async_cb); |
|
|
4464 | \& ev_async_start (EV_A_ &u\->async_w); |
|
|
4465 | \& |
|
|
4466 | \& pthread_mutex_init (&u\->lock, 0); |
|
|
4467 | \& pthread_cond_init (&u\->invoke_cv, 0); |
|
|
4468 | \& |
|
|
4469 | \& // now associate this with the loop |
|
|
4470 | \& ev_set_userdata (EV_A_ u); |
|
|
4471 | \& ev_set_invoke_pending_cb (EV_A_ l_invoke); |
|
|
4472 | \& ev_set_loop_release_cb (EV_A_ l_release, l_acquire); |
|
|
4473 | \& |
|
|
4474 | \& // then create the thread running ev_loop |
|
|
4475 | \& pthread_create (&u\->tid, 0, l_run, EV_A); |
|
|
4476 | \& } |
|
|
4477 | .Ve |
|
|
4478 | .PP |
|
|
4479 | The callback for the \f(CW\*(C`ev_async\*(C'\fR watcher does nothing: the watcher is used |
|
|
4480 | solely to wake up the event loop so it takes notice of any new watchers |
|
|
4481 | that might have been added: |
|
|
4482 | .PP |
|
|
4483 | .Vb 5 |
|
|
4484 | \& static void |
|
|
4485 | \& async_cb (EV_P_ ev_async *w, int revents) |
|
|
4486 | \& { |
|
|
4487 | \& // just used for the side effects |
|
|
4488 | \& } |
|
|
4489 | .Ve |
|
|
4490 | .PP |
|
|
4491 | The \f(CW\*(C`l_release\*(C'\fR and \f(CW\*(C`l_acquire\*(C'\fR callbacks simply unlock/lock the mutex |
|
|
4492 | protecting the loop data, respectively. |
|
|
4493 | .PP |
|
|
4494 | .Vb 6 |
|
|
4495 | \& static void |
|
|
4496 | \& l_release (EV_P) |
|
|
4497 | \& { |
|
|
4498 | \& userdata *u = ev_userdata (EV_A); |
|
|
4499 | \& pthread_mutex_unlock (&u\->lock); |
|
|
4500 | \& } |
|
|
4501 | \& |
|
|
4502 | \& static void |
|
|
4503 | \& l_acquire (EV_P) |
|
|
4504 | \& { |
|
|
4505 | \& userdata *u = ev_userdata (EV_A); |
|
|
4506 | \& pthread_mutex_lock (&u\->lock); |
|
|
4507 | \& } |
|
|
4508 | .Ve |
|
|
4509 | .PP |
|
|
4510 | The event loop thread first acquires the mutex, and then jumps straight |
|
|
4511 | into \f(CW\*(C`ev_run\*(C'\fR: |
|
|
4512 | .PP |
|
|
4513 | .Vb 4 |
|
|
4514 | \& void * |
|
|
4515 | \& l_run (void *thr_arg) |
|
|
4516 | \& { |
|
|
4517 | \& struct ev_loop *loop = (struct ev_loop *)thr_arg; |
|
|
4518 | \& |
|
|
4519 | \& l_acquire (EV_A); |
|
|
4520 | \& pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0); |
|
|
4521 | \& ev_run (EV_A_ 0); |
|
|
4522 | \& l_release (EV_A); |
|
|
4523 | \& |
|
|
4524 | \& return 0; |
|
|
4525 | \& } |
|
|
4526 | .Ve |
|
|
4527 | .PP |
|
|
4528 | Instead of invoking all pending watchers, the \f(CW\*(C`l_invoke\*(C'\fR callback will |
|
|
4529 | signal the main thread via some unspecified mechanism (signals? pipe |
|
|
4530 | writes? \f(CW\*(C`Async::Interrupt\*(C'\fR?) and then waits until all pending watchers |
|
|
4531 | have been called (in a while loop because a) spurious wakeups are possible |
|
|
4532 | and b) skipping inter-thread-communication when there are no pending |
|
|
4533 | watchers is very beneficial): |
|
|
4534 | .PP |
|
|
4535 | .Vb 4 |
|
|
4536 | \& static void |
|
|
4537 | \& l_invoke (EV_P) |
|
|
4538 | \& { |
|
|
4539 | \& userdata *u = ev_userdata (EV_A); |
|
|
4540 | \& |
|
|
4541 | \& while (ev_pending_count (EV_A)) |
|
|
4542 | \& { |
|
|
4543 | \& wake_up_other_thread_in_some_magic_or_not_so_magic_way (); |
|
|
4544 | \& pthread_cond_wait (&u\->invoke_cv, &u\->lock); |
|
|
4545 | \& } |
|
|
4546 | \& } |
|
|
4547 | .Ve |
|
|
4548 | .PP |
|
|
4549 | Now, whenever the main thread gets told to invoke pending watchers, it |
|
|
4550 | will grab the lock, call \f(CW\*(C`ev_invoke_pending\*(C'\fR and then signal the loop |
|
|
4551 | thread to continue: |
|
|
4552 | .PP |
|
|
4553 | .Vb 4 |
|
|
4554 | \& static void |
|
|
4555 | \& real_invoke_pending (EV_P) |
|
|
4556 | \& { |
|
|
4557 | \& userdata *u = ev_userdata (EV_A); |
|
|
4558 | \& |
|
|
4559 | \& pthread_mutex_lock (&u\->lock); |
|
|
4560 | \& ev_invoke_pending (EV_A); |
|
|
4561 | \& pthread_cond_signal (&u\->invoke_cv); |
|
|
4562 | \& pthread_mutex_unlock (&u\->lock); |
|
|
4563 | \& } |
|
|
4564 | .Ve |
|
|
4565 | .PP |
|
|
4566 | Whenever you want to start/stop a watcher or do other modifications to an |
|
|
4567 | event loop, you will now have to lock: |
|
|
4568 | .PP |
|
|
4569 | .Vb 2 |
|
|
4570 | \& ev_timer timeout_watcher; |
|
|
4571 | \& userdata *u = ev_userdata (EV_A); |
|
|
4572 | \& |
|
|
4573 | \& ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.); |
|
|
4574 | \& |
|
|
4575 | \& pthread_mutex_lock (&u\->lock); |
|
|
4576 | \& ev_timer_start (EV_A_ &timeout_watcher); |
|
|
4577 | \& ev_async_send (EV_A_ &u\->async_w); |
|
|
4578 | \& pthread_mutex_unlock (&u\->lock); |
|
|
4579 | .Ve |
|
|
4580 | .PP |
|
|
4581 | Note that sending the \f(CW\*(C`ev_async\*(C'\fR watcher is required because otherwise |
|
|
4582 | an event loop currently blocking in the kernel will have no knowledge |
|
|
4583 | about the newly added timer. By waking up the loop it will pick up any new |
|
|
4584 | watchers in the next event loop iteration. |
|
|
4585 | .PP |
5324 | .PP |
4586 | \fI\s-1COROUTINES\s0\fR |
5325 | \fI\s-1COROUTINES\s0\fR |
4587 | .IX Subsection "COROUTINES" |
5326 | .IX Subsection "COROUTINES" |
4588 | .PP |
5327 | .PP |
4589 | Libev is very accommodating to coroutines (\*(L"cooperative threads\*(R"): |
5328 | Libev is very accommodating to coroutines (\*(L"cooperative threads\*(R"): |
… | |
… | |
4594 | that you must not do this from \f(CW\*(C`ev_periodic\*(C'\fR reschedule callbacks. |
5333 | that you must not do this from \f(CW\*(C`ev_periodic\*(C'\fR reschedule callbacks. |
4595 | .PP |
5334 | .PP |
4596 | Care has been taken to ensure that libev does not keep local state inside |
5335 | Care has been taken to ensure that libev does not keep local state inside |
4597 | \&\f(CW\*(C`ev_run\*(C'\fR, and other calls do not usually allow for coroutine switches as |
5336 | \&\f(CW\*(C`ev_run\*(C'\fR, and other calls do not usually allow for coroutine switches as |
4598 | they do not call any callbacks. |
5337 | they do not call any callbacks. |
4599 | .SS "\s-1COMPILER\s0 \s-1WARNINGS\s0" |
5338 | .SS "\s-1COMPILER WARNINGS\s0" |
4600 | .IX Subsection "COMPILER WARNINGS" |
5339 | .IX Subsection "COMPILER WARNINGS" |
4601 | Depending on your compiler and compiler settings, you might get no or a |
5340 | Depending on your compiler and compiler settings, you might get no or a |
4602 | lot of warnings when compiling libev code. Some people are apparently |
5341 | lot of warnings when compiling libev code. Some people are apparently |
4603 | scared by this. |
5342 | scared by this. |
4604 | .PP |
5343 | .PP |
… | |
… | |
4656 | .PP |
5395 | .PP |
4657 | If you need, for some reason, empty reports from valgrind for your project |
5396 | If you need, for some reason, empty reports from valgrind for your project |
4658 | I suggest using suppression lists. |
5397 | I suggest using suppression lists. |
4659 | .SH "PORTABILITY NOTES" |
5398 | .SH "PORTABILITY NOTES" |
4660 | .IX Header "PORTABILITY NOTES" |
5399 | .IX Header "PORTABILITY NOTES" |
4661 | .SS "\s-1GNU/LINUX\s0 32 \s-1BIT\s0 \s-1LIMITATIONS\s0" |
5400 | .SS "\s-1GNU/LINUX 32 BIT LIMITATIONS\s0" |
4662 | .IX Subsection "GNU/LINUX 32 BIT LIMITATIONS" |
5401 | .IX Subsection "GNU/LINUX 32 BIT LIMITATIONS" |
4663 | GNU/Linux is the only common platform that supports 64 bit file/large file |
5402 | GNU/Linux is the only common platform that supports 64 bit file/large file |
4664 | interfaces but \fIdisables\fR them by default. |
5403 | interfaces but \fIdisables\fR them by default. |
4665 | .PP |
5404 | .PP |
4666 | That means that libev compiled in the default environment doesn't support |
5405 | That means that libev compiled in the default environment doesn't support |
4667 | files larger than 2GiB or so, which mainly affects \f(CW\*(C`ev_stat\*(C'\fR watchers. |
5406 | files larger than 2GiB or so, which mainly affects \f(CW\*(C`ev_stat\*(C'\fR watchers. |
4668 | .PP |
5407 | .PP |
4669 | Unfortunately, many programs try to work around this GNU/Linux issue |
5408 | Unfortunately, many programs try to work around this GNU/Linux issue |
4670 | by enabling the large file \s-1API\s0, which makes them incompatible with the |
5409 | by enabling the large file \s-1API,\s0 which makes them incompatible with the |
4671 | standard libev compiled for their system. |
5410 | standard libev compiled for their system. |
4672 | .PP |
5411 | .PP |
4673 | Likewise, libev cannot enable the large file \s-1API\s0 itself as this would |
5412 | Likewise, libev cannot enable the large file \s-1API\s0 itself as this would |
4674 | suddenly make it incompatible to the default compile time environment, |
5413 | suddenly make it incompatible to the default compile time environment, |
4675 | i.e. all programs not using special compile switches. |
5414 | i.e. all programs not using special compile switches. |
4676 | .SS "\s-1OS/X\s0 \s-1AND\s0 \s-1DARWIN\s0 \s-1BUGS\s0" |
5415 | .SS "\s-1OS/X AND DARWIN BUGS\s0" |
4677 | .IX Subsection "OS/X AND DARWIN BUGS" |
5416 | .IX Subsection "OS/X AND DARWIN BUGS" |
4678 | The whole thing is a bug if you ask me \- basically any system interface |
5417 | The whole thing is a bug if you ask me \- basically any system interface |
4679 | you touch is broken, whether it is locales, poll, kqueue or even the |
5418 | you touch is broken, whether it is locales, poll, kqueue or even the |
4680 | OpenGL drivers. |
5419 | OpenGL drivers. |
4681 | .PP |
5420 | .PP |
… | |
… | |
4703 | .PP |
5442 | .PP |
4704 | \fI\f(CI\*(C`select\*(C'\fI is buggy\fR |
5443 | \fI\f(CI\*(C`select\*(C'\fI is buggy\fR |
4705 | .IX Subsection "select is buggy" |
5444 | .IX Subsection "select is buggy" |
4706 | .PP |
5445 | .PP |
4707 | All that's left is \f(CW\*(C`select\*(C'\fR, and of course Apple found a way to fuck this |
5446 | All that's left is \f(CW\*(C`select\*(C'\fR, and of course Apple found a way to fuck this |
4708 | one up as well: On \s-1OS/X\s0, \f(CW\*(C`select\*(C'\fR actively limits the number of file |
5447 | one up as well: On \s-1OS/X,\s0 \f(CW\*(C`select\*(C'\fR actively limits the number of file |
4709 | descriptors you can pass in to 1024 \- your program suddenly crashes when |
5448 | descriptors you can pass in to 1024 \- your program suddenly crashes when |
4710 | you use more. |
5449 | you use more. |
4711 | .PP |
5450 | .PP |
4712 | There is an undocumented \*(L"workaround\*(R" for this \- defining |
5451 | There is an undocumented \*(L"workaround\*(R" for this \- defining |
4713 | \&\f(CW\*(C`_DARWIN_UNLIMITED_SELECT\*(C'\fR, which libev tries to use, so select \fIshould\fR |
5452 | \&\f(CW\*(C`_DARWIN_UNLIMITED_SELECT\*(C'\fR, which libev tries to use, so select \fIshould\fR |
4714 | work on \s-1OS/X\s0. |
5453 | work on \s-1OS/X.\s0 |
4715 | .SS "\s-1SOLARIS\s0 \s-1PROBLEMS\s0 \s-1AND\s0 \s-1WORKAROUNDS\s0" |
5454 | .SS "\s-1SOLARIS PROBLEMS AND WORKAROUNDS\s0" |
4716 | .IX Subsection "SOLARIS PROBLEMS AND WORKAROUNDS" |
5455 | .IX Subsection "SOLARIS PROBLEMS AND WORKAROUNDS" |
4717 | \fI\f(CI\*(C`errno\*(C'\fI reentrancy\fR |
5456 | \fI\f(CI\*(C`errno\*(C'\fI reentrancy\fR |
4718 | .IX Subsection "errno reentrancy" |
5457 | .IX Subsection "errno reentrancy" |
4719 | .PP |
5458 | .PP |
4720 | The default compile environment on Solaris is unfortunately so |
5459 | The default compile environment on Solaris is unfortunately so |
… | |
… | |
4737 | great. |
5476 | great. |
4738 | .PP |
5477 | .PP |
4739 | If you can't get it to work, you can try running the program by setting |
5478 | If you can't get it to work, you can try running the program by setting |
4740 | the environment variable \f(CW\*(C`LIBEV_FLAGS=3\*(C'\fR to only allow \f(CW\*(C`poll\*(C'\fR and |
5479 | the environment variable \f(CW\*(C`LIBEV_FLAGS=3\*(C'\fR to only allow \f(CW\*(C`poll\*(C'\fR and |
4741 | \&\f(CW\*(C`select\*(C'\fR backends. |
5480 | \&\f(CW\*(C`select\*(C'\fR backends. |
4742 | .SS "\s-1AIX\s0 \s-1POLL\s0 \s-1BUG\s0" |
5481 | .SS "\s-1AIX POLL BUG\s0" |
4743 | .IX Subsection "AIX POLL BUG" |
5482 | .IX Subsection "AIX POLL BUG" |
4744 | \&\s-1AIX\s0 unfortunately has a broken \f(CW\*(C`poll.h\*(C'\fR header. Libev works around |
5483 | \&\s-1AIX\s0 unfortunately has a broken \f(CW\*(C`poll.h\*(C'\fR header. Libev works around |
4745 | this by trying to avoid the poll backend altogether (i.e. it's not even |
5484 | this by trying to avoid the poll backend altogether (i.e. it's not even |
4746 | compiled in), which normally isn't a big problem as \f(CW\*(C`select\*(C'\fR works fine |
5485 | compiled in), which normally isn't a big problem as \f(CW\*(C`select\*(C'\fR works fine |
4747 | with large bitsets on \s-1AIX\s0, and \s-1AIX\s0 is dead anyway. |
5486 | with large bitsets on \s-1AIX,\s0 and \s-1AIX\s0 is dead anyway. |
4748 | .SS "\s-1WIN32\s0 \s-1PLATFORM\s0 \s-1LIMITATIONS\s0 \s-1AND\s0 \s-1WORKAROUNDS\s0" |
5487 | .SS "\s-1WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS\s0" |
4749 | .IX Subsection "WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS" |
5488 | .IX Subsection "WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS" |
4750 | \fIGeneral issues\fR |
5489 | \fIGeneral issues\fR |
4751 | .IX Subsection "General issues" |
5490 | .IX Subsection "General issues" |
4752 | .PP |
5491 | .PP |
4753 | Win32 doesn't support any of the standards (e.g. \s-1POSIX\s0) that libev |
5492 | Win32 doesn't support any of the standards (e.g. \s-1POSIX\s0) that libev |
4754 | requires, and its I/O model is fundamentally incompatible with the \s-1POSIX\s0 |
5493 | requires, and its I/O model is fundamentally incompatible with the \s-1POSIX\s0 |
4755 | model. Libev still offers limited functionality on this platform in |
5494 | model. Libev still offers limited functionality on this platform in |
4756 | the form of the \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR backend, and only supports socket |
5495 | the form of the \f(CW\*(C`EVBACKEND_SELECT\*(C'\fR backend, and only supports socket |
4757 | descriptors. This only applies when using Win32 natively, not when using |
5496 | descriptors. This only applies when using Win32 natively, not when using |
4758 | e.g. cygwin. Actually, it only applies to the microsofts own compilers, |
5497 | e.g. cygwin. Actually, it only applies to the microsofts own compilers, |
4759 | as every compielr comes with a slightly differently broken/incompatible |
5498 | as every compiler comes with a slightly differently broken/incompatible |
4760 | environment. |
5499 | environment. |
4761 | .PP |
5500 | .PP |
4762 | Lifting these limitations would basically require the full |
5501 | Lifting these limitations would basically require the full |
4763 | re-implementation of the I/O system. If you are into this kind of thing, |
5502 | re-implementation of the I/O system. If you are into this kind of thing, |
4764 | then note that glib does exactly that for you in a very portable way (note |
5503 | then note that glib does exactly that for you in a very portable way (note |
… | |
… | |
4822 | \& #define EV_USE_SELECT 1 |
5561 | \& #define EV_USE_SELECT 1 |
4823 | \& #define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */ |
5562 | \& #define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */ |
4824 | .Ve |
5563 | .Ve |
4825 | .PP |
5564 | .PP |
4826 | Note that winsockets handling of fd sets is O(n), so you can easily get a |
5565 | Note that winsockets handling of fd sets is O(n), so you can easily get a |
4827 | complexity in the O(nA\*^X) range when using win32. |
5566 | complexity in the O(nX) range when using win32. |
4828 | .PP |
5567 | .PP |
4829 | \fILimited number of file descriptors\fR |
5568 | \fILimited number of file descriptors\fR |
4830 | .IX Subsection "Limited number of file descriptors" |
5569 | .IX Subsection "Limited number of file descriptors" |
4831 | .PP |
5570 | .PP |
4832 | Windows has numerous arbitrary (and low) limits on things. |
5571 | Windows has numerous arbitrary (and low) limits on things. |
… | |
… | |
4848 | by calling \f(CW\*(C`_setmaxstdio\*(C'\fR, which can increase this limit to \f(CW2048\fR |
5587 | by calling \f(CW\*(C`_setmaxstdio\*(C'\fR, which can increase this limit to \f(CW2048\fR |
4849 | (another arbitrary limit), but is broken in many versions of the Microsoft |
5588 | (another arbitrary limit), but is broken in many versions of the Microsoft |
4850 | runtime libraries. This might get you to about \f(CW512\fR or \f(CW2048\fR sockets |
5589 | runtime libraries. This might get you to about \f(CW512\fR or \f(CW2048\fR sockets |
4851 | (depending on windows version and/or the phase of the moon). To get more, |
5590 | (depending on windows version and/or the phase of the moon). To get more, |
4852 | you need to wrap all I/O functions and provide your own fd management, but |
5591 | you need to wrap all I/O functions and provide your own fd management, but |
4853 | the cost of calling select (O(nA\*^X)) will likely make this unworkable. |
5592 | the cost of calling select (O(nX)) will likely make this unworkable. |
4854 | .SS "\s-1PORTABILITY\s0 \s-1REQUIREMENTS\s0" |
5593 | .SS "\s-1PORTABILITY REQUIREMENTS\s0" |
4855 | .IX Subsection "PORTABILITY REQUIREMENTS" |
5594 | .IX Subsection "PORTABILITY REQUIREMENTS" |
4856 | In addition to a working ISO-C implementation and of course the |
5595 | In addition to a working ISO-C implementation and of course the |
4857 | backend-specific APIs, libev relies on a few additional extensions: |
5596 | backend-specific APIs, libev relies on a few additional extensions: |
4858 | .ie n .IP """void (*)(ev_watcher_type *, int revents)"" must have compatible calling conventions regardless of ""ev_watcher_type *""." 4 |
5597 | .ie n .IP """void (*)(ev_watcher_type *, int revents)"" must have compatible calling conventions regardless of ""ev_watcher_type *""." 4 |
4859 | .el .IP "\f(CWvoid (*)(ev_watcher_type *, int revents)\fR must have compatible calling conventions regardless of \f(CWev_watcher_type *\fR." 4 |
5598 | .el .IP "\f(CWvoid (*)(ev_watcher_type *, int revents)\fR must have compatible calling conventions regardless of \f(CWev_watcher_type *\fR." 4 |
4860 | .IX Item "void (*)(ev_watcher_type *, int revents) must have compatible calling conventions regardless of ev_watcher_type *." |
5599 | .IX Item "void (*)(ev_watcher_type *, int revents) must have compatible calling conventions regardless of ev_watcher_type *." |
4861 | Libev assumes not only that all watcher pointers have the same internal |
5600 | Libev assumes not only that all watcher pointers have the same internal |
4862 | structure (guaranteed by \s-1POSIX\s0 but not by \s-1ISO\s0 C for example), but it also |
5601 | structure (guaranteed by \s-1POSIX\s0 but not by \s-1ISO C\s0 for example), but it also |
4863 | assumes that the same (machine) code can be used to call any watcher |
5602 | assumes that the same (machine) code can be used to call any watcher |
4864 | callback: The watcher callbacks have different type signatures, but libev |
5603 | callback: The watcher callbacks have different type signatures, but libev |
4865 | calls them using an \f(CW\*(C`ev_watcher *\*(C'\fR internally. |
5604 | calls them using an \f(CW\*(C`ev_watcher *\*(C'\fR internally. |
|
|
5605 | .IP "null pointers and integer zero are represented by 0 bytes" 4 |
|
|
5606 | .IX Item "null pointers and integer zero are represented by 0 bytes" |
|
|
5607 | Libev uses \f(CW\*(C`memset\*(C'\fR to initialise structs and arrays to \f(CW0\fR bytes, and |
|
|
5608 | relies on this setting pointers and integers to null. |
4866 | .IP "pointer accesses must be thread-atomic" 4 |
5609 | .IP "pointer accesses must be thread-atomic" 4 |
4867 | .IX Item "pointer accesses must be thread-atomic" |
5610 | .IX Item "pointer accesses must be thread-atomic" |
4868 | Accessing a pointer value must be atomic, it must both be readable and |
5611 | Accessing a pointer value must be atomic, it must both be readable and |
4869 | writable in one piece \- this is the case on all current architectures. |
5612 | writable in one piece \- this is the case on all current architectures. |
4870 | .ie n .IP """sig_atomic_t volatile"" must be thread-atomic as well" 4 |
5613 | .ie n .IP """sig_atomic_t volatile"" must be thread-atomic as well" 4 |
… | |
… | |
4883 | thread\*(R" or will block signals process-wide, both behaviours would |
5626 | thread\*(R" or will block signals process-wide, both behaviours would |
4884 | be compatible with libev. Interaction between \f(CW\*(C`sigprocmask\*(C'\fR and |
5627 | be compatible with libev. Interaction between \f(CW\*(C`sigprocmask\*(C'\fR and |
4885 | \&\f(CW\*(C`pthread_sigmask\*(C'\fR could complicate things, however. |
5628 | \&\f(CW\*(C`pthread_sigmask\*(C'\fR could complicate things, however. |
4886 | .Sp |
5629 | .Sp |
4887 | The most portable way to handle signals is to block signals in all threads |
5630 | The most portable way to handle signals is to block signals in all threads |
4888 | except the initial one, and run the default loop in the initial thread as |
5631 | except the initial one, and run the signal handling loop in the initial |
4889 | well. |
5632 | thread as well. |
4890 | .ie n .IP """long"" must be large enough for common memory allocation sizes" 4 |
5633 | .ie n .IP """long"" must be large enough for common memory allocation sizes" 4 |
4891 | .el .IP "\f(CWlong\fR must be large enough for common memory allocation sizes" 4 |
5634 | .el .IP "\f(CWlong\fR must be large enough for common memory allocation sizes" 4 |
4892 | .IX Item "long must be large enough for common memory allocation sizes" |
5635 | .IX Item "long must be large enough for common memory allocation sizes" |
4893 | To improve portability and simplify its \s-1API\s0, libev uses \f(CW\*(C`long\*(C'\fR internally |
5636 | To improve portability and simplify its \s-1API,\s0 libev uses \f(CW\*(C`long\*(C'\fR internally |
4894 | instead of \f(CW\*(C`size_t\*(C'\fR when allocating its data structures. On non-POSIX |
5637 | instead of \f(CW\*(C`size_t\*(C'\fR when allocating its data structures. On non-POSIX |
4895 | systems (Microsoft...) this might be unexpectedly low, but is still at |
5638 | systems (Microsoft...) this might be unexpectedly low, but is still at |
4896 | least 31 bits everywhere, which is enough for hundreds of millions of |
5639 | least 31 bits everywhere, which is enough for hundreds of millions of |
4897 | watchers. |
5640 | watchers. |
4898 | .ie n .IP """double"" must hold a time value in seconds with enough accuracy" 4 |
5641 | .ie n .IP """double"" must hold a time value in seconds with enough accuracy" 4 |
… | |
… | |
4900 | .IX Item "double must hold a time value in seconds with enough accuracy" |
5643 | .IX Item "double must hold a time value in seconds with enough accuracy" |
4901 | The type \f(CW\*(C`double\*(C'\fR is used to represent timestamps. It is required to |
5644 | The type \f(CW\*(C`double\*(C'\fR is used to represent timestamps. It is required to |
4902 | have at least 51 bits of mantissa (and 9 bits of exponent), which is |
5645 | have at least 51 bits of mantissa (and 9 bits of exponent), which is |
4903 | good enough for at least into the year 4000 with millisecond accuracy |
5646 | good enough for at least into the year 4000 with millisecond accuracy |
4904 | (the design goal for libev). This requirement is overfulfilled by |
5647 | (the design goal for libev). This requirement is overfulfilled by |
4905 | implementations using \s-1IEEE\s0 754, which is basically all existing ones. With |
5648 | implementations using \s-1IEEE 754,\s0 which is basically all existing ones. |
|
|
5649 | .Sp |
4906 | \&\s-1IEEE\s0 754 doubles, you get microsecond accuracy until at least 2200. |
5650 | With \s-1IEEE 754\s0 doubles, you get microsecond accuracy until at least the |
|
|
5651 | year 2255 (and millisecond accuracy till the year 287396 \- by then, libev |
|
|
5652 | is either obsolete or somebody patched it to use \f(CW\*(C`long double\*(C'\fR or |
|
|
5653 | something like that, just kidding). |
4907 | .PP |
5654 | .PP |
4908 | If you know of other additional requirements drop me a note. |
5655 | If you know of other additional requirements drop me a note. |
4909 | .SH "ALGORITHMIC COMPLEXITIES" |
5656 | .SH "ALGORITHMIC COMPLEXITIES" |
4910 | .IX Header "ALGORITHMIC COMPLEXITIES" |
5657 | .IX Header "ALGORITHMIC COMPLEXITIES" |
4911 | In this section the complexities of (many of) the algorithms used inside |
5658 | In this section the complexities of (many of) the algorithms used inside |
… | |
… | |
4965 | .IX Item "Processing ev_async_send: O(number_of_async_watchers)" |
5712 | .IX Item "Processing ev_async_send: O(number_of_async_watchers)" |
4966 | .IP "Processing signals: O(max_signal_number)" 4 |
5713 | .IP "Processing signals: O(max_signal_number)" 4 |
4967 | .IX Item "Processing signals: O(max_signal_number)" |
5714 | .IX Item "Processing signals: O(max_signal_number)" |
4968 | .PD |
5715 | .PD |
4969 | Sending involves a system call \fIiff\fR there were no other \f(CW\*(C`ev_async_send\*(C'\fR |
5716 | Sending involves a system call \fIiff\fR there were no other \f(CW\*(C`ev_async_send\*(C'\fR |
4970 | calls in the current loop iteration. Checking for async and signal events |
5717 | calls in the current loop iteration and the loop is currently |
|
|
5718 | blocked. Checking for async and signal events involves iterating over all |
4971 | involves iterating over all running async watchers or all signal numbers. |
5719 | running async watchers or all signal numbers. |
4972 | .SH "PORTING FROM LIBEV 3.X TO 4.X" |
5720 | .SH "PORTING FROM LIBEV 3.X TO 4.X" |
4973 | .IX Header "PORTING FROM LIBEV 3.X TO 4.X" |
5721 | .IX Header "PORTING FROM LIBEV 3.X TO 4.X" |
4974 | The major version 4 introduced some incompatible changes to the \s-1API\s0. |
5722 | The major version 4 introduced some incompatible changes to the \s-1API.\s0 |
4975 | .PP |
5723 | .PP |
4976 | At the moment, the \f(CW\*(C`ev.h\*(C'\fR header file provides compatibility definitions |
5724 | At the moment, the \f(CW\*(C`ev.h\*(C'\fR header file provides compatibility definitions |
4977 | for all changes, so most programs should still compile. The compatibility |
5725 | for all changes, so most programs should still compile. The compatibility |
4978 | layer might be removed in later versions of libev, so better update to the |
5726 | layer might be removed in later versions of libev, so better update to the |
4979 | new \s-1API\s0 early than late. |
5727 | new \s-1API\s0 early than late. |
4980 | .ie n .IP """EV_COMPAT3"" backwards compatibility mechanism" 4 |
5728 | .ie n .IP """EV_COMPAT3"" backwards compatibility mechanism" 4 |
4981 | .el .IP "\f(CWEV_COMPAT3\fR backwards compatibility mechanism" 4 |
5729 | .el .IP "\f(CWEV_COMPAT3\fR backwards compatibility mechanism" 4 |
4982 | .IX Item "EV_COMPAT3 backwards compatibility mechanism" |
5730 | .IX Item "EV_COMPAT3 backwards compatibility mechanism" |
4983 | The backward compatibility mechanism can be controlled by |
5731 | The backward compatibility mechanism can be controlled by |
4984 | \&\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 |
5732 | \&\f(CW\*(C`EV_COMPAT3\*(C'\fR. See \*(L"\s-1PREPROCESSOR SYMBOLS/MACROS\*(R"\s0 in the \*(L"\s-1EMBEDDING\*(R"\s0 |
4985 | section. |
5733 | section. |
4986 | .ie n .IP """ev_default_destroy"" and ""ev_default_fork"" have been removed" 4 |
5734 | .ie n .IP """ev_default_destroy"" and ""ev_default_fork"" have been removed" 4 |
4987 | .el .IP "\f(CWev_default_destroy\fR and \f(CWev_default_fork\fR have been removed" 4 |
5735 | .el .IP "\f(CWev_default_destroy\fR and \f(CWev_default_fork\fR have been removed" 4 |
4988 | .IX Item "ev_default_destroy and ev_default_fork have been removed" |
5736 | .IX Item "ev_default_destroy and ev_default_fork have been removed" |
4989 | These calls can be replaced easily by their \f(CW\*(C`ev_loop_xxx\*(C'\fR counterparts: |
5737 | These calls can be replaced easily by their \f(CW\*(C`ev_loop_xxx\*(C'\fR counterparts: |
… | |
… | |
5029 | .SH "GLOSSARY" |
5777 | .SH "GLOSSARY" |
5030 | .IX Header "GLOSSARY" |
5778 | .IX Header "GLOSSARY" |
5031 | .IP "active" 4 |
5779 | .IP "active" 4 |
5032 | .IX Item "active" |
5780 | .IX Item "active" |
5033 | A watcher is active as long as it has been started and not yet stopped. |
5781 | A watcher is active as long as it has been started and not yet stopped. |
5034 | See \*(L"\s-1WATCHER\s0 \s-1STATES\s0\*(R" for details. |
5782 | See \*(L"\s-1WATCHER STATES\*(R"\s0 for details. |
5035 | .IP "application" 4 |
5783 | .IP "application" 4 |
5036 | .IX Item "application" |
5784 | .IX Item "application" |
5037 | In this document, an application is whatever is using libev. |
5785 | In this document, an application is whatever is using libev. |
5038 | .IP "backend" 4 |
5786 | .IP "backend" 4 |
5039 | .IX Item "backend" |
5787 | .IX Item "backend" |
… | |
… | |
5066 | The model used to describe how an event loop handles and processes |
5814 | The model used to describe how an event loop handles and processes |
5067 | watchers and events. |
5815 | watchers and events. |
5068 | .IP "pending" 4 |
5816 | .IP "pending" 4 |
5069 | .IX Item "pending" |
5817 | .IX Item "pending" |
5070 | A watcher is pending as soon as the corresponding event has been |
5818 | A watcher is pending as soon as the corresponding event has been |
5071 | detected. See \*(L"\s-1WATCHER\s0 \s-1STATES\s0\*(R" for details. |
5819 | detected. See \*(L"\s-1WATCHER STATES\*(R"\s0 for details. |
5072 | .IP "real time" 4 |
5820 | .IP "real time" 4 |
5073 | .IX Item "real time" |
5821 | .IX Item "real time" |
5074 | The physical time that is observed. It is apparently strictly monotonic :) |
5822 | The physical time that is observed. It is apparently strictly monotonic :) |
5075 | .IP "wall-clock time" 4 |
5823 | .IP "wall-clock time" 4 |
5076 | .IX Item "wall-clock time" |
5824 | .IX Item "wall-clock time" |
5077 | The time and date as shown on clocks. Unlike real time, it can actually |
5825 | The time and date as shown on clocks. Unlike real time, it can actually |
5078 | be wrong and jump forwards and backwards, e.g. when the you adjust your |
5826 | be wrong and jump forwards and backwards, e.g. when you adjust your |
5079 | clock. |
5827 | clock. |
5080 | .IP "watcher" 4 |
5828 | .IP "watcher" 4 |
5081 | .IX Item "watcher" |
5829 | .IX Item "watcher" |
5082 | A data structure that describes interest in certain events. Watchers need |
5830 | A data structure that describes interest in certain events. Watchers need |
5083 | to be started (attached to an event loop) before they can receive events. |
5831 | to be started (attached to an event loop) before they can receive events. |
5084 | .SH "AUTHOR" |
5832 | .SH "AUTHOR" |
5085 | .IX Header "AUTHOR" |
5833 | .IX Header "AUTHOR" |
5086 | Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael |
5834 | Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael |
5087 | Magnusson and Emanuele Giaquinta. |
5835 | Magnusson and Emanuele Giaquinta, and minor corrections by many others. |