… | |
… | |
48 | return 0; |
48 | return 0; |
49 | } |
49 | } |
50 | |
50 | |
51 | =head1 DESCRIPTION |
51 | =head1 DESCRIPTION |
52 | |
52 | |
|
|
53 | The newest version of this document is also available as a html-formatted |
|
|
54 | web page you might find easier to navigate when reading it for the first |
|
|
55 | time: L<http://cvs.schmorp.de/libev/ev.html>. |
|
|
56 | |
53 | Libev is an event loop: you register interest in certain events (such as a |
57 | Libev is an event loop: you register interest in certain events (such as a |
54 | file descriptor being readable or a timeout occuring), and it will manage |
58 | file descriptor being readable or a timeout occurring), and it will manage |
55 | these event sources and provide your program with events. |
59 | these event sources and provide your program with events. |
56 | |
60 | |
57 | To do this, it must take more or less complete control over your process |
61 | To do this, it must take more or less complete control over your process |
58 | (or thread) by executing the I<event loop> handler, and will then |
62 | (or thread) by executing the I<event loop> handler, and will then |
59 | communicate events via a callback mechanism. |
63 | communicate events via a callback mechanism. |
… | |
… | |
63 | details of the event, and then hand it over to libev by I<starting> the |
67 | details of the event, and then hand it over to libev by I<starting> the |
64 | watcher. |
68 | watcher. |
65 | |
69 | |
66 | =head1 FEATURES |
70 | =head1 FEATURES |
67 | |
71 | |
68 | Libev supports C<select>, C<poll>, the linux-specific C<epoll>, the |
72 | Libev supports C<select>, C<poll>, the Linux-specific C<epoll>, the |
69 | bsd-specific C<kqueue> and the solaris-specific event port mechanisms |
73 | BSD-specific C<kqueue> and the Solaris-specific event port mechanisms |
70 | for file descriptor events (C<ev_io>), relative timers (C<ev_timer>), |
74 | for file descriptor events (C<ev_io>), the Linux C<inotify> interface |
|
|
75 | (for C<ev_stat>), relative timers (C<ev_timer>), absolute timers |
71 | absolute timers with customised rescheduling (C<ev_periodic>), synchronous |
76 | with customised rescheduling (C<ev_periodic>), synchronous signals |
72 | signals (C<ev_signal>), process status change events (C<ev_child>), and |
77 | (C<ev_signal>), process status change events (C<ev_child>), and event |
73 | event watchers dealing with the event loop mechanism itself (C<ev_idle>, |
78 | watchers dealing with the event loop mechanism itself (C<ev_idle>, |
74 | C<ev_embed>, C<ev_prepare> and C<ev_check> watchers) as well as |
79 | C<ev_embed>, C<ev_prepare> and C<ev_check> watchers) as well as |
75 | file watchers (C<ev_stat>) and even limited support for fork events |
80 | file watchers (C<ev_stat>) and even limited support for fork events |
76 | (C<ev_fork>). |
81 | (C<ev_fork>). |
77 | |
82 | |
78 | It also is quite fast (see this |
83 | It also is quite fast (see this |
… | |
… | |
93 | Libev represents time as a single floating point number, representing the |
98 | Libev represents time as a single floating point number, representing the |
94 | (fractional) number of seconds since the (POSIX) epoch (somewhere near |
99 | (fractional) number of seconds since the (POSIX) epoch (somewhere near |
95 | the beginning of 1970, details are complicated, don't ask). This type is |
100 | the beginning of 1970, details are complicated, don't ask). This type is |
96 | called C<ev_tstamp>, which is what you should use too. It usually aliases |
101 | called C<ev_tstamp>, which is what you should use too. It usually aliases |
97 | to the C<double> type in C, and when you need to do any calculations on |
102 | to the C<double> type in C, and when you need to do any calculations on |
98 | it, you should treat it as such. |
103 | it, you should treat it as some floatingpoint value. Unlike the name |
|
|
104 | component C<stamp> might indicate, it is also used for time differences |
|
|
105 | throughout libev. |
99 | |
106 | |
100 | =head1 GLOBAL FUNCTIONS |
107 | =head1 GLOBAL FUNCTIONS |
101 | |
108 | |
102 | These functions can be called anytime, even before initialising the |
109 | These functions can be called anytime, even before initialising the |
103 | library in any way. |
110 | library in any way. |
… | |
… | |
112 | |
119 | |
113 | =item int ev_version_major () |
120 | =item int ev_version_major () |
114 | |
121 | |
115 | =item int ev_version_minor () |
122 | =item int ev_version_minor () |
116 | |
123 | |
117 | You can find out the major and minor version numbers of the library |
124 | You can find out the major and minor ABI version numbers of the library |
118 | you linked against by calling the functions C<ev_version_major> and |
125 | you linked against by calling the functions C<ev_version_major> and |
119 | C<ev_version_minor>. If you want, you can compare against the global |
126 | C<ev_version_minor>. If you want, you can compare against the global |
120 | symbols C<EV_VERSION_MAJOR> and C<EV_VERSION_MINOR>, which specify the |
127 | symbols C<EV_VERSION_MAJOR> and C<EV_VERSION_MINOR>, which specify the |
121 | version of the library your program was compiled against. |
128 | version of the library your program was compiled against. |
122 | |
129 | |
|
|
130 | These version numbers refer to the ABI version of the library, not the |
|
|
131 | release version. |
|
|
132 | |
123 | Usually, it's a good idea to terminate if the major versions mismatch, |
133 | Usually, it's a good idea to terminate if the major versions mismatch, |
124 | as this indicates an incompatible change. Minor versions are usually |
134 | as this indicates an incompatible change. Minor versions are usually |
125 | compatible to older versions, so a larger minor version alone is usually |
135 | compatible to older versions, so a larger minor version alone is usually |
126 | not a problem. |
136 | not a problem. |
127 | |
137 | |
128 | Example: Make sure we haven't accidentally been linked against the wrong |
138 | Example: Make sure we haven't accidentally been linked against the wrong |
129 | version. |
139 | version. |
… | |
… | |
162 | C<ev_embeddable_backends () & ev_supported_backends ()>, likewise for |
172 | C<ev_embeddable_backends () & ev_supported_backends ()>, likewise for |
163 | recommended ones. |
173 | recommended ones. |
164 | |
174 | |
165 | See the description of C<ev_embed> watchers for more info. |
175 | See the description of C<ev_embed> watchers for more info. |
166 | |
176 | |
167 | =item ev_set_allocator (void *(*cb)(void *ptr, size_t size)) |
177 | =item ev_set_allocator (void *(*cb)(void *ptr, long size)) |
168 | |
178 | |
169 | Sets the allocation function to use (the prototype and semantics are |
179 | Sets the allocation function to use (the prototype is similar - the |
170 | identical to the realloc C function). It is used to allocate and free |
180 | semantics is identical - to the realloc C function). It is used to |
171 | memory (no surprises here). If it returns zero when memory needs to be |
181 | allocate and free memory (no surprises here). If it returns zero when |
172 | allocated, the library might abort or take some potentially destructive |
182 | memory needs to be allocated, the library might abort or take some |
173 | action. The default is your system realloc function. |
183 | potentially destructive action. The default is your system realloc |
|
|
184 | function. |
174 | |
185 | |
175 | You could override this function in high-availability programs to, say, |
186 | You could override this function in high-availability programs to, say, |
176 | free some memory if it cannot allocate memory, to use a special allocator, |
187 | free some memory if it cannot allocate memory, to use a special allocator, |
177 | or even to sleep a while and retry until some memory is available. |
188 | or even to sleep a while and retry until some memory is available. |
178 | |
189 | |
… | |
… | |
264 | C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will |
275 | C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will |
265 | override the flags completely if it is found in the environment. This is |
276 | override the flags completely if it is found in the environment. This is |
266 | useful to try out specific backends to test their performance, or to work |
277 | useful to try out specific backends to test their performance, or to work |
267 | around bugs. |
278 | around bugs. |
268 | |
279 | |
|
|
280 | =item C<EVFLAG_FORKCHECK> |
|
|
281 | |
|
|
282 | Instead of calling C<ev_default_fork> or C<ev_loop_fork> manually after |
|
|
283 | a fork, you can also make libev check for a fork in each iteration by |
|
|
284 | enabling this flag. |
|
|
285 | |
|
|
286 | This works by calling C<getpid ()> on every iteration of the loop, |
|
|
287 | and thus this might slow down your event loop if you do a lot of loop |
|
|
288 | iterations and little real work, but is usually not noticeable (on my |
|
|
289 | Linux system for example, C<getpid> is actually a simple 5-insn sequence |
|
|
290 | without a syscall and thus I<very> fast, but my Linux system also has |
|
|
291 | C<pthread_atfork> which is even faster). |
|
|
292 | |
|
|
293 | The big advantage of this flag is that you can forget about fork (and |
|
|
294 | forget about forgetting to tell libev about forking) when you use this |
|
|
295 | flag. |
|
|
296 | |
|
|
297 | This flag setting cannot be overriden or specified in the C<LIBEV_FLAGS> |
|
|
298 | environment variable. |
|
|
299 | |
269 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
300 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
270 | |
301 | |
271 | This is your standard select(2) backend. Not I<completely> standard, as |
302 | This is your standard select(2) backend. Not I<completely> standard, as |
272 | libev tries to roll its own fd_set with no limits on the number of fds, |
303 | libev tries to roll its own fd_set with no limits on the number of fds, |
273 | but if that fails, expect a fairly low limit on the number of fds when |
304 | but if that fails, expect a fairly low limit on the number of fds when |
… | |
… | |
282 | lot of inactive fds). It scales similarly to select, i.e. O(total_fds). |
313 | lot of inactive fds). It scales similarly to select, i.e. O(total_fds). |
283 | |
314 | |
284 | =item C<EVBACKEND_EPOLL> (value 4, Linux) |
315 | =item C<EVBACKEND_EPOLL> (value 4, Linux) |
285 | |
316 | |
286 | For few fds, this backend is a bit little slower than poll and select, |
317 | For few fds, this backend is a bit little slower than poll and select, |
287 | but it scales phenomenally better. While poll and select usually scale like |
318 | but it scales phenomenally better. While poll and select usually scale |
288 | O(total_fds) where n is the total number of fds (or the highest fd), epoll scales |
319 | like O(total_fds) where n is the total number of fds (or the highest fd), |
289 | either O(1) or O(active_fds). |
320 | epoll scales either O(1) or O(active_fds). The epoll design has a number |
|
|
321 | of shortcomings, such as silently dropping events in some hard-to-detect |
|
|
322 | cases and rewuiring a syscall per fd change, no fork support and bad |
|
|
323 | support for dup: |
290 | |
324 | |
291 | While stopping and starting an I/O watcher in the same iteration will |
325 | While stopping, setting and starting an I/O watcher in the same iteration |
292 | result in some caching, there is still a syscall per such incident |
326 | will result in some caching, there is still a syscall per such incident |
293 | (because the fd could point to a different file description now), so its |
327 | (because the fd could point to a different file description now), so its |
294 | best to avoid that. Also, dup()ed file descriptors might not work very |
328 | best to avoid that. Also, C<dup ()>'ed file descriptors might not work |
295 | well if you register events for both fds. |
329 | very well if you register events for both fds. |
296 | |
330 | |
297 | Please note that epoll sometimes generates spurious notifications, so you |
331 | Please note that epoll sometimes generates spurious notifications, so you |
298 | need to use non-blocking I/O or other means to avoid blocking when no data |
332 | need to use non-blocking I/O or other means to avoid blocking when no data |
299 | (or space) is available. |
333 | (or space) is available. |
300 | |
334 | |
301 | =item C<EVBACKEND_KQUEUE> (value 8, most BSD clones) |
335 | =item C<EVBACKEND_KQUEUE> (value 8, most BSD clones) |
302 | |
336 | |
303 | Kqueue deserves special mention, as at the time of this writing, it |
337 | Kqueue deserves special mention, as at the time of this writing, it |
304 | was broken on all BSDs except NetBSD (usually it doesn't work with |
338 | was broken on I<all> BSDs (usually it doesn't work with anything but |
305 | anything but sockets and pipes, except on Darwin, where of course its |
339 | sockets and pipes, except on Darwin, where of course it's completely |
|
|
340 | useless. On NetBSD, it seems to work for all the FD types I tested, so it |
306 | completely useless). For this reason its not being "autodetected" |
341 | is used by default there). For this reason it's not being "autodetected" |
307 | unless you explicitly specify it explicitly in the flags (i.e. using |
342 | unless you explicitly specify it explicitly in the flags (i.e. using |
308 | C<EVBACKEND_KQUEUE>). |
343 | C<EVBACKEND_KQUEUE>) or libev was compiled on a known-to-be-good (-enough) |
|
|
344 | system like NetBSD. |
309 | |
345 | |
310 | It scales in the same way as the epoll backend, but the interface to the |
346 | It scales in the same way as the epoll backend, but the interface to the |
311 | kernel is more efficient (which says nothing about its actual speed, of |
347 | kernel is more efficient (which says nothing about its actual speed, |
312 | course). While starting and stopping an I/O watcher does not cause an |
348 | of course). While stopping, setting and starting an I/O watcher does |
313 | extra syscall as with epoll, it still adds up to four event changes per |
349 | never cause an extra syscall as with epoll, it still adds up to two event |
314 | incident, so its best to avoid that. |
350 | changes per incident, support for C<fork ()> is very bad and it drops fds |
|
|
351 | silently in similarly hard-to-detetc cases. |
315 | |
352 | |
316 | =item C<EVBACKEND_DEVPOLL> (value 16, Solaris 8) |
353 | =item C<EVBACKEND_DEVPOLL> (value 16, Solaris 8) |
317 | |
354 | |
318 | This is not implemented yet (and might never be). |
355 | This is not implemented yet (and might never be). |
319 | |
356 | |
320 | =item C<EVBACKEND_PORT> (value 32, Solaris 10) |
357 | =item C<EVBACKEND_PORT> (value 32, Solaris 10) |
321 | |
358 | |
322 | This uses the Solaris 10 port mechanism. As with everything on Solaris, |
359 | This uses the Solaris 10 event port mechanism. As with everything on Solaris, |
323 | it's really slow, but it still scales very well (O(active_fds)). |
360 | it's really slow, but it still scales very well (O(active_fds)). |
324 | |
361 | |
325 | Please note that solaris ports can result in a lot of spurious |
362 | Please note that solaris event ports can deliver a lot of spurious |
326 | notifications, so you need to use non-blocking I/O or other means to avoid |
363 | notifications, so you need to use non-blocking I/O or other means to avoid |
327 | blocking when no data (or space) is available. |
364 | blocking when no data (or space) is available. |
328 | |
365 | |
329 | =item C<EVBACKEND_ALL> |
366 | =item C<EVBACKEND_ALL> |
330 | |
367 | |
… | |
… | |
373 | Destroys the default loop again (frees all memory and kernel state |
410 | Destroys the default loop again (frees all memory and kernel state |
374 | etc.). None of the active event watchers will be stopped in the normal |
411 | etc.). None of the active event watchers will be stopped in the normal |
375 | sense, so e.g. C<ev_is_active> might still return true. It is your |
412 | sense, so e.g. C<ev_is_active> might still return true. It is your |
376 | responsibility to either stop all watchers cleanly yoursef I<before> |
413 | responsibility to either stop all watchers cleanly yoursef I<before> |
377 | calling this function, or cope with the fact afterwards (which is usually |
414 | calling this function, or cope with the fact afterwards (which is usually |
378 | the easiest thing, youc na just ignore the watchers and/or C<free ()> them |
415 | the easiest thing, you can just ignore the watchers and/or C<free ()> them |
379 | for example). |
416 | for example). |
|
|
417 | |
|
|
418 | Note that certain global state, such as signal state, will not be freed by |
|
|
419 | this function, and related watchers (such as signal and child watchers) |
|
|
420 | would need to be stopped manually. |
|
|
421 | |
|
|
422 | In general it is not advisable to call this function except in the |
|
|
423 | rare occasion where you really need to free e.g. the signal handling |
|
|
424 | pipe fds. If you need dynamically allocated loops it is better to use |
|
|
425 | C<ev_loop_new> and C<ev_loop_destroy>). |
380 | |
426 | |
381 | =item ev_loop_destroy (loop) |
427 | =item ev_loop_destroy (loop) |
382 | |
428 | |
383 | Like C<ev_default_destroy>, but destroys an event loop created by an |
429 | Like C<ev_default_destroy>, but destroys an event loop created by an |
384 | earlier call to C<ev_loop_new>. |
430 | earlier call to C<ev_loop_new>. |
… | |
… | |
408 | |
454 | |
409 | Like C<ev_default_fork>, but acts on an event loop created by |
455 | Like C<ev_default_fork>, but acts on an event loop created by |
410 | C<ev_loop_new>. Yes, you have to call this on every allocated event loop |
456 | C<ev_loop_new>. Yes, you have to call this on every allocated event loop |
411 | after fork, and how you do this is entirely your own problem. |
457 | after fork, and how you do this is entirely your own problem. |
412 | |
458 | |
|
|
459 | =item unsigned int ev_loop_count (loop) |
|
|
460 | |
|
|
461 | Returns the count of loop iterations for the loop, which is identical to |
|
|
462 | the number of times libev did poll for new events. It starts at C<0> and |
|
|
463 | happily wraps around with enough iterations. |
|
|
464 | |
|
|
465 | This value can sometimes be useful as a generation counter of sorts (it |
|
|
466 | "ticks" the number of loop iterations), as it roughly corresponds with |
|
|
467 | C<ev_prepare> and C<ev_check> calls. |
|
|
468 | |
413 | =item unsigned int ev_backend (loop) |
469 | =item unsigned int ev_backend (loop) |
414 | |
470 | |
415 | Returns one of the C<EVBACKEND_*> flags indicating the event backend in |
471 | Returns one of the C<EVBACKEND_*> flags indicating the event backend in |
416 | use. |
472 | use. |
417 | |
473 | |
… | |
… | |
419 | |
475 | |
420 | Returns the current "event loop time", which is the time the event loop |
476 | Returns the current "event loop time", which is the time the event loop |
421 | received events and started processing them. This timestamp does not |
477 | received events and started processing them. This timestamp does not |
422 | change as long as callbacks are being processed, and this is also the base |
478 | change as long as callbacks are being processed, and this is also the base |
423 | time used for relative timers. You can treat it as the timestamp of the |
479 | time used for relative timers. You can treat it as the timestamp of the |
424 | event occuring (or more correctly, libev finding out about it). |
480 | event occurring (or more correctly, libev finding out about it). |
425 | |
481 | |
426 | =item ev_loop (loop, int flags) |
482 | =item ev_loop (loop, int flags) |
427 | |
483 | |
428 | Finally, this is it, the event handler. This function usually is called |
484 | Finally, this is it, the event handler. This function usually is called |
429 | after you initialised all your watchers and you want to start handling |
485 | after you initialised all your watchers and you want to start handling |
… | |
… | |
450 | libev watchers. However, a pair of C<ev_prepare>/C<ev_check> watchers is |
506 | libev watchers. However, a pair of C<ev_prepare>/C<ev_check> watchers is |
451 | usually a better approach for this kind of thing. |
507 | usually a better approach for this kind of thing. |
452 | |
508 | |
453 | Here are the gory details of what C<ev_loop> does: |
509 | Here are the gory details of what C<ev_loop> does: |
454 | |
510 | |
|
|
511 | - Before the first iteration, call any pending watchers. |
455 | * If there are no active watchers (reference count is zero), return. |
512 | * If there are no active watchers (reference count is zero), return. |
456 | - Queue prepare watchers and then call all outstanding watchers. |
513 | - Queue all prepare watchers and then call all outstanding watchers. |
457 | - If we have been forked, recreate the kernel state. |
514 | - If we have been forked, recreate the kernel state. |
458 | - Update the kernel state with all outstanding changes. |
515 | - Update the kernel state with all outstanding changes. |
459 | - Update the "event loop time". |
516 | - Update the "event loop time". |
460 | - Calculate for how long to block. |
517 | - Calculate for how long to block. |
461 | - Block the process, waiting for any events. |
518 | - Block the process, waiting for any events. |
… | |
… | |
700 | =item bool ev_is_pending (ev_TYPE *watcher) |
757 | =item bool ev_is_pending (ev_TYPE *watcher) |
701 | |
758 | |
702 | Returns a true value iff the watcher is pending, (i.e. it has outstanding |
759 | Returns a true value iff the watcher is pending, (i.e. it has outstanding |
703 | events but its callback has not yet been invoked). As long as a watcher |
760 | events but its callback has not yet been invoked). As long as a watcher |
704 | is pending (but not active) you must not call an init function on it (but |
761 | is pending (but not active) you must not call an init function on it (but |
705 | C<ev_TYPE_set> is safe) and you must make sure the watcher is available to |
762 | C<ev_TYPE_set> is safe), you must not change its priority, and you must |
706 | libev (e.g. you cnanot C<free ()> it). |
763 | make sure the watcher is available to libev (e.g. you cannot C<free ()> |
|
|
764 | it). |
707 | |
765 | |
708 | =item callback ev_cb (ev_TYPE *watcher) |
766 | =item callback ev_cb (ev_TYPE *watcher) |
709 | |
767 | |
710 | Returns the callback currently set on the watcher. |
768 | Returns the callback currently set on the watcher. |
711 | |
769 | |
712 | =item ev_cb_set (ev_TYPE *watcher, callback) |
770 | =item ev_cb_set (ev_TYPE *watcher, callback) |
713 | |
771 | |
714 | Change the callback. You can change the callback at virtually any time |
772 | Change the callback. You can change the callback at virtually any time |
715 | (modulo threads). |
773 | (modulo threads). |
|
|
774 | |
|
|
775 | =item ev_set_priority (ev_TYPE *watcher, priority) |
|
|
776 | |
|
|
777 | =item int ev_priority (ev_TYPE *watcher) |
|
|
778 | |
|
|
779 | Set and query the priority of the watcher. The priority is a small |
|
|
780 | integer between C<EV_MAXPRI> (default: C<2>) and C<EV_MINPRI> |
|
|
781 | (default: C<-2>). Pending watchers with higher priority will be invoked |
|
|
782 | before watchers with lower priority, but priority will not keep watchers |
|
|
783 | from being executed (except for C<ev_idle> watchers). |
|
|
784 | |
|
|
785 | This means that priorities are I<only> used for ordering callback |
|
|
786 | invocation after new events have been received. This is useful, for |
|
|
787 | example, to reduce latency after idling, or more often, to bind two |
|
|
788 | watchers on the same event and make sure one is called first. |
|
|
789 | |
|
|
790 | If you need to suppress invocation when higher priority events are pending |
|
|
791 | you need to look at C<ev_idle> watchers, which provide this functionality. |
|
|
792 | |
|
|
793 | You I<must not> change the priority of a watcher as long as it is active or |
|
|
794 | pending. |
|
|
795 | |
|
|
796 | The default priority used by watchers when no priority has been set is |
|
|
797 | always C<0>, which is supposed to not be too high and not be too low :). |
|
|
798 | |
|
|
799 | Setting a priority outside the range of C<EV_MINPRI> to C<EV_MAXPRI> is |
|
|
800 | fine, as long as you do not mind that the priority value you query might |
|
|
801 | or might not have been adjusted to be within valid range. |
|
|
802 | |
|
|
803 | =item ev_invoke (loop, ev_TYPE *watcher, int revents) |
|
|
804 | |
|
|
805 | Invoke the C<watcher> with the given C<loop> and C<revents>. Neither |
|
|
806 | C<loop> nor C<revents> need to be valid as long as the watcher callback |
|
|
807 | can deal with that fact. |
|
|
808 | |
|
|
809 | =item int ev_clear_pending (loop, ev_TYPE *watcher) |
|
|
810 | |
|
|
811 | If the watcher is pending, this function returns clears its pending status |
|
|
812 | and returns its C<revents> bitset (as if its callback was invoked). If the |
|
|
813 | watcher isn't pending it does nothing and returns C<0>. |
716 | |
814 | |
717 | =back |
815 | =back |
718 | |
816 | |
719 | |
817 | |
720 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
818 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
… | |
… | |
826 | it is best to always use non-blocking I/O: An extra C<read>(2) returning |
924 | it is best to always use non-blocking I/O: An extra C<read>(2) returning |
827 | C<EAGAIN> is far preferable to a program hanging until some data arrives. |
925 | C<EAGAIN> is far preferable to a program hanging until some data arrives. |
828 | |
926 | |
829 | If you cannot run the fd in non-blocking mode (for example you should not |
927 | If you cannot run the fd in non-blocking mode (for example you should not |
830 | play around with an Xlib connection), then you have to seperately re-test |
928 | play around with an Xlib connection), then you have to seperately re-test |
831 | wether a file descriptor is really ready with a known-to-be good interface |
929 | whether a file descriptor is really ready with a known-to-be good interface |
832 | such as poll (fortunately in our Xlib example, Xlib already does this on |
930 | such as poll (fortunately in our Xlib example, Xlib already does this on |
833 | its own, so its quite safe to use). |
931 | its own, so its quite safe to use). |
|
|
932 | |
|
|
933 | =head3 The special problem of disappearing file descriptors |
|
|
934 | |
|
|
935 | Some backends (e.g. kqueue, epoll) need to be told about closing a file |
|
|
936 | descriptor (either by calling C<close> explicitly or by any other means, |
|
|
937 | such as C<dup>). The reason is that you register interest in some file |
|
|
938 | descriptor, but when it goes away, the operating system will silently drop |
|
|
939 | this interest. If another file descriptor with the same number then is |
|
|
940 | registered with libev, there is no efficient way to see that this is, in |
|
|
941 | fact, a different file descriptor. |
|
|
942 | |
|
|
943 | To avoid having to explicitly tell libev about such cases, libev follows |
|
|
944 | the following policy: Each time C<ev_io_set> is being called, libev |
|
|
945 | will assume that this is potentially a new file descriptor, otherwise |
|
|
946 | it is assumed that the file descriptor stays the same. That means that |
|
|
947 | you I<have> to call C<ev_io_set> (or C<ev_io_init>) when you change the |
|
|
948 | descriptor even if the file descriptor number itself did not change. |
|
|
949 | |
|
|
950 | This is how one would do it normally anyway, the important point is that |
|
|
951 | the libev application should not optimise around libev but should leave |
|
|
952 | optimisations to libev. |
|
|
953 | |
|
|
954 | =head3 The special problem of dup'ed file descriptors |
|
|
955 | |
|
|
956 | Some backends (e.g. epoll), cannot register events for file descriptors, |
|
|
957 | but only events for the underlying file descriptions. That menas when you |
|
|
958 | have C<dup ()>'ed file descriptors and register events for them, only one |
|
|
959 | file descriptor might actually receive events. |
|
|
960 | |
|
|
961 | There is no workaorund possible except not registering events |
|
|
962 | for potentially C<dup ()>'ed file descriptors or to resort to |
|
|
963 | C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>. |
|
|
964 | |
|
|
965 | =head3 The special problem of fork |
|
|
966 | |
|
|
967 | Some backends (epoll, kqueue) do not support C<fork ()> at all or exhibit |
|
|
968 | useless behaviour. Libev fully supports fork, but needs to be told about |
|
|
969 | it in the child. |
|
|
970 | |
|
|
971 | To support fork in your programs, you either have to call |
|
|
972 | C<ev_default_fork ()> or C<ev_loop_fork ()> after a fork in the child, |
|
|
973 | enable C<EVFLAG_FORKCHECK>, or resort to C<EVBACKEND_SELECT> or |
|
|
974 | C<EVBACKEND_POLL>. |
|
|
975 | |
|
|
976 | |
|
|
977 | =head3 Watcher-Specific Functions |
834 | |
978 | |
835 | =over 4 |
979 | =over 4 |
836 | |
980 | |
837 | =item ev_io_init (ev_io *, callback, int fd, int events) |
981 | =item ev_io_init (ev_io *, callback, int fd, int events) |
838 | |
982 | |
… | |
… | |
892 | |
1036 | |
893 | The callback is guarenteed to be invoked only when its timeout has passed, |
1037 | The callback is guarenteed to be invoked only when its timeout has passed, |
894 | but if multiple timers become ready during the same loop iteration then |
1038 | but if multiple timers become ready during the same loop iteration then |
895 | order of execution is undefined. |
1039 | order of execution is undefined. |
896 | |
1040 | |
|
|
1041 | =head3 Watcher-Specific Functions and Data Members |
|
|
1042 | |
897 | =over 4 |
1043 | =over 4 |
898 | |
1044 | |
899 | =item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat) |
1045 | =item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat) |
900 | |
1046 | |
901 | =item ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat) |
1047 | =item ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat) |
… | |
… | |
914 | =item ev_timer_again (loop) |
1060 | =item ev_timer_again (loop) |
915 | |
1061 | |
916 | This will act as if the timer timed out and restart it again if it is |
1062 | This will act as if the timer timed out and restart it again if it is |
917 | repeating. The exact semantics are: |
1063 | repeating. The exact semantics are: |
918 | |
1064 | |
|
|
1065 | If the timer is pending, its pending status is cleared. |
|
|
1066 | |
919 | If the timer is started but nonrepeating, stop it. |
1067 | If the timer is started but nonrepeating, stop it (as if it timed out). |
920 | |
1068 | |
921 | If the timer is repeating, either start it if necessary (with the repeat |
1069 | If the timer is repeating, either start it if necessary (with the |
922 | value), or reset the running timer to the repeat value. |
1070 | C<repeat> value), or reset the running timer to the C<repeat> value. |
923 | |
1071 | |
924 | This sounds a bit complicated, but here is a useful and typical |
1072 | This sounds a bit complicated, but here is a useful and typical |
925 | example: Imagine you have a tcp connection and you want a so-called |
1073 | example: Imagine you have a tcp connection and you want a so-called idle |
926 | idle timeout, that is, you want to be called when there have been, |
1074 | timeout, that is, you want to be called when there have been, say, 60 |
927 | say, 60 seconds of inactivity on the socket. The easiest way to do |
1075 | seconds of inactivity on the socket. The easiest way to do this is to |
928 | this is to configure an C<ev_timer> with C<after>=C<repeat>=C<60> and calling |
1076 | configure an C<ev_timer> with a C<repeat> value of C<60> and then call |
929 | C<ev_timer_again> each time you successfully read or write some data. If |
1077 | C<ev_timer_again> each time you successfully read or write some data. If |
930 | you go into an idle state where you do not expect data to travel on the |
1078 | you go into an idle state where you do not expect data to travel on the |
931 | socket, you can stop the timer, and again will automatically restart it if |
1079 | socket, you can C<ev_timer_stop> the timer, and C<ev_timer_again> will |
932 | need be. |
1080 | automatically restart it if need be. |
933 | |
1081 | |
934 | You can also ignore the C<after> value and C<ev_timer_start> altogether |
1082 | That means you can ignore the C<after> value and C<ev_timer_start> |
935 | and only ever use the C<repeat> value: |
1083 | altogether and only ever use the C<repeat> value and C<ev_timer_again>: |
936 | |
1084 | |
937 | ev_timer_init (timer, callback, 0., 5.); |
1085 | ev_timer_init (timer, callback, 0., 5.); |
938 | ev_timer_again (loop, timer); |
1086 | ev_timer_again (loop, timer); |
939 | ... |
1087 | ... |
940 | timer->again = 17.; |
1088 | timer->again = 17.; |
941 | ev_timer_again (loop, timer); |
1089 | ev_timer_again (loop, timer); |
942 | ... |
1090 | ... |
943 | timer->again = 10.; |
1091 | timer->again = 10.; |
944 | ev_timer_again (loop, timer); |
1092 | ev_timer_again (loop, timer); |
945 | |
1093 | |
946 | This is more efficient then stopping/starting the timer eahc time you want |
1094 | This is more slightly efficient then stopping/starting the timer each time |
947 | to modify its timeout value. |
1095 | you want to modify its timeout value. |
948 | |
1096 | |
949 | =item ev_tstamp repeat [read-write] |
1097 | =item ev_tstamp repeat [read-write] |
950 | |
1098 | |
951 | The current C<repeat> value. Will be used each time the watcher times out |
1099 | The current C<repeat> value. Will be used each time the watcher times out |
952 | or C<ev_timer_again> is called and determines the next timeout (if any), |
1100 | or C<ev_timer_again> is called and determines the next timeout (if any), |
… | |
… | |
994 | but on wallclock time (absolute time). You can tell a periodic watcher |
1142 | but on wallclock time (absolute time). You can tell a periodic watcher |
995 | to trigger "at" some specific point in time. For example, if you tell a |
1143 | to trigger "at" some specific point in time. For example, if you tell a |
996 | periodic watcher to trigger in 10 seconds (by specifiying e.g. C<ev_now () |
1144 | periodic watcher to trigger in 10 seconds (by specifiying e.g. C<ev_now () |
997 | + 10.>) and then reset your system clock to the last year, then it will |
1145 | + 10.>) and then reset your system clock to the last year, then it will |
998 | take a year to trigger the event (unlike an C<ev_timer>, which would trigger |
1146 | take a year to trigger the event (unlike an C<ev_timer>, which would trigger |
999 | roughly 10 seconds later and of course not if you reset your system time |
1147 | roughly 10 seconds later). |
1000 | again). |
|
|
1001 | |
1148 | |
1002 | They can also be used to implement vastly more complex timers, such as |
1149 | They can also be used to implement vastly more complex timers, such as |
1003 | triggering an event on eahc midnight, local time. |
1150 | triggering an event on each midnight, local time or other, complicated, |
|
|
1151 | rules. |
1004 | |
1152 | |
1005 | As with timers, the callback is guarenteed to be invoked only when the |
1153 | As with timers, the callback is guarenteed to be invoked only when the |
1006 | time (C<at>) has been passed, but if multiple periodic timers become ready |
1154 | time (C<at>) has been passed, but if multiple periodic timers become ready |
1007 | during the same loop iteration then order of execution is undefined. |
1155 | during the same loop iteration then order of execution is undefined. |
1008 | |
1156 | |
|
|
1157 | =head3 Watcher-Specific Functions and Data Members |
|
|
1158 | |
1009 | =over 4 |
1159 | =over 4 |
1010 | |
1160 | |
1011 | =item ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb) |
1161 | =item ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb) |
1012 | |
1162 | |
1013 | =item ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb) |
1163 | =item ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb) |
… | |
… | |
1015 | Lots of arguments, lets sort it out... There are basically three modes of |
1165 | Lots of arguments, lets sort it out... There are basically three modes of |
1016 | operation, and we will explain them from simplest to complex: |
1166 | operation, and we will explain them from simplest to complex: |
1017 | |
1167 | |
1018 | =over 4 |
1168 | =over 4 |
1019 | |
1169 | |
1020 | =item * absolute timer (interval = reschedule_cb = 0) |
1170 | =item * absolute timer (at = time, interval = reschedule_cb = 0) |
1021 | |
1171 | |
1022 | In this configuration the watcher triggers an event at the wallclock time |
1172 | In this configuration the watcher triggers an event at the wallclock time |
1023 | C<at> and doesn't repeat. It will not adjust when a time jump occurs, |
1173 | C<at> and doesn't repeat. It will not adjust when a time jump occurs, |
1024 | that is, if it is to be run at January 1st 2011 then it will run when the |
1174 | that is, if it is to be run at January 1st 2011 then it will run when the |
1025 | system time reaches or surpasses this time. |
1175 | system time reaches or surpasses this time. |
1026 | |
1176 | |
1027 | =item * non-repeating interval timer (interval > 0, reschedule_cb = 0) |
1177 | =item * non-repeating interval timer (at = offset, interval > 0, reschedule_cb = 0) |
1028 | |
1178 | |
1029 | In this mode the watcher will always be scheduled to time out at the next |
1179 | In this mode the watcher will always be scheduled to time out at the next |
1030 | C<at + N * interval> time (for some integer N) and then repeat, regardless |
1180 | C<at + N * interval> time (for some integer N, which can also be negative) |
1031 | of any time jumps. |
1181 | and then repeat, regardless of any time jumps. |
1032 | |
1182 | |
1033 | This can be used to create timers that do not drift with respect to system |
1183 | This can be used to create timers that do not drift with respect to system |
1034 | time: |
1184 | time: |
1035 | |
1185 | |
1036 | ev_periodic_set (&periodic, 0., 3600., 0); |
1186 | ev_periodic_set (&periodic, 0., 3600., 0); |
… | |
… | |
1042 | |
1192 | |
1043 | Another way to think about it (for the mathematically inclined) is that |
1193 | Another way to think about it (for the mathematically inclined) is that |
1044 | C<ev_periodic> will try to run the callback in this mode at the next possible |
1194 | C<ev_periodic> will try to run the callback in this mode at the next possible |
1045 | time where C<time = at (mod interval)>, regardless of any time jumps. |
1195 | time where C<time = at (mod interval)>, regardless of any time jumps. |
1046 | |
1196 | |
|
|
1197 | For numerical stability it is preferable that the C<at> value is near |
|
|
1198 | C<ev_now ()> (the current time), but there is no range requirement for |
|
|
1199 | this value. |
|
|
1200 | |
1047 | =item * manual reschedule mode (reschedule_cb = callback) |
1201 | =item * manual reschedule mode (at and interval ignored, reschedule_cb = callback) |
1048 | |
1202 | |
1049 | In this mode the values for C<interval> and C<at> are both being |
1203 | In this mode the values for C<interval> and C<at> are both being |
1050 | ignored. Instead, each time the periodic watcher gets scheduled, the |
1204 | ignored. Instead, each time the periodic watcher gets scheduled, the |
1051 | reschedule callback will be called with the watcher as first, and the |
1205 | reschedule callback will be called with the watcher as first, and the |
1052 | current time as second argument. |
1206 | current time as second argument. |
1053 | |
1207 | |
1054 | NOTE: I<This callback MUST NOT stop or destroy any periodic watcher, |
1208 | NOTE: I<This callback MUST NOT stop or destroy any periodic watcher, |
1055 | ever, or make any event loop modifications>. If you need to stop it, |
1209 | ever, or make any event loop modifications>. If you need to stop it, |
1056 | return C<now + 1e30> (or so, fudge fudge) and stop it afterwards (e.g. by |
1210 | return C<now + 1e30> (or so, fudge fudge) and stop it afterwards (e.g. by |
1057 | starting a prepare watcher). |
1211 | starting an C<ev_prepare> watcher, which is legal). |
1058 | |
1212 | |
1059 | Its prototype is C<ev_tstamp (*reschedule_cb)(struct ev_periodic *w, |
1213 | Its prototype is C<ev_tstamp (*reschedule_cb)(struct ev_periodic *w, |
1060 | ev_tstamp now)>, e.g.: |
1214 | ev_tstamp now)>, e.g.: |
1061 | |
1215 | |
1062 | static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now) |
1216 | static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now) |
… | |
… | |
1085 | Simply stops and restarts the periodic watcher again. This is only useful |
1239 | Simply stops and restarts the periodic watcher again. This is only useful |
1086 | when you changed some parameters or the reschedule callback would return |
1240 | when you changed some parameters or the reschedule callback would return |
1087 | a different time than the last time it was called (e.g. in a crond like |
1241 | a different time than the last time it was called (e.g. in a crond like |
1088 | program when the crontabs have changed). |
1242 | program when the crontabs have changed). |
1089 | |
1243 | |
|
|
1244 | =item ev_tstamp offset [read-write] |
|
|
1245 | |
|
|
1246 | When repeating, this contains the offset value, otherwise this is the |
|
|
1247 | absolute point in time (the C<at> value passed to C<ev_periodic_set>). |
|
|
1248 | |
|
|
1249 | Can be modified any time, but changes only take effect when the periodic |
|
|
1250 | timer fires or C<ev_periodic_again> is being called. |
|
|
1251 | |
1090 | =item ev_tstamp interval [read-write] |
1252 | =item ev_tstamp interval [read-write] |
1091 | |
1253 | |
1092 | The current interval value. Can be modified any time, but changes only |
1254 | The current interval value. Can be modified any time, but changes only |
1093 | take effect when the periodic timer fires or C<ev_periodic_again> is being |
1255 | take effect when the periodic timer fires or C<ev_periodic_again> is being |
1094 | called. |
1256 | called. |
… | |
… | |
1096 | =item ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read-write] |
1258 | =item ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read-write] |
1097 | |
1259 | |
1098 | The current reschedule callback, or C<0>, if this functionality is |
1260 | The current reschedule callback, or C<0>, if this functionality is |
1099 | switched off. Can be changed any time, but changes only take effect when |
1261 | switched off. Can be changed any time, but changes only take effect when |
1100 | the periodic timer fires or C<ev_periodic_again> is being called. |
1262 | the periodic timer fires or C<ev_periodic_again> is being called. |
|
|
1263 | |
|
|
1264 | =item ev_tstamp at [read-only] |
|
|
1265 | |
|
|
1266 | When active, contains the absolute time that the watcher is supposed to |
|
|
1267 | trigger next. |
1101 | |
1268 | |
1102 | =back |
1269 | =back |
1103 | |
1270 | |
1104 | Example: Call a callback every hour, or, more precisely, whenever the |
1271 | Example: Call a callback every hour, or, more precisely, whenever the |
1105 | system clock is divisible by 3600. The callback invocation times have |
1272 | system clock is divisible by 3600. The callback invocation times have |
… | |
… | |
1147 | with the kernel (thus it coexists with your own signal handlers as long |
1314 | with the kernel (thus it coexists with your own signal handlers as long |
1148 | as you don't register any with libev). Similarly, when the last signal |
1315 | as you don't register any with libev). Similarly, when the last signal |
1149 | watcher for a signal is stopped libev will reset the signal handler to |
1316 | watcher for a signal is stopped libev will reset the signal handler to |
1150 | SIG_DFL (regardless of what it was set to before). |
1317 | SIG_DFL (regardless of what it was set to before). |
1151 | |
1318 | |
|
|
1319 | =head3 Watcher-Specific Functions and Data Members |
|
|
1320 | |
1152 | =over 4 |
1321 | =over 4 |
1153 | |
1322 | |
1154 | =item ev_signal_init (ev_signal *, callback, int signum) |
1323 | =item ev_signal_init (ev_signal *, callback, int signum) |
1155 | |
1324 | |
1156 | =item ev_signal_set (ev_signal *, int signum) |
1325 | =item ev_signal_set (ev_signal *, int signum) |
… | |
… | |
1167 | |
1336 | |
1168 | =head2 C<ev_child> - watch out for process status changes |
1337 | =head2 C<ev_child> - watch out for process status changes |
1169 | |
1338 | |
1170 | Child watchers trigger when your process receives a SIGCHLD in response to |
1339 | Child watchers trigger when your process receives a SIGCHLD in response to |
1171 | some child status changes (most typically when a child of yours dies). |
1340 | some child status changes (most typically when a child of yours dies). |
|
|
1341 | |
|
|
1342 | =head3 Watcher-Specific Functions and Data Members |
1172 | |
1343 | |
1173 | =over 4 |
1344 | =over 4 |
1174 | |
1345 | |
1175 | =item ev_child_init (ev_child *, callback, int pid) |
1346 | =item ev_child_init (ev_child *, callback, int pid) |
1176 | |
1347 | |
… | |
… | |
1220 | The path does not need to exist: changing from "path exists" to "path does |
1391 | The path does not need to exist: changing from "path exists" to "path does |
1221 | not exist" is a status change like any other. The condition "path does |
1392 | not exist" is a status change like any other. The condition "path does |
1222 | not exist" is signified by the C<st_nlink> field being zero (which is |
1393 | not exist" is signified by the C<st_nlink> field being zero (which is |
1223 | otherwise always forced to be at least one) and all the other fields of |
1394 | otherwise always forced to be at least one) and all the other fields of |
1224 | the stat buffer having unspecified contents. |
1395 | the stat buffer having unspecified contents. |
|
|
1396 | |
|
|
1397 | The path I<should> be absolute and I<must not> end in a slash. If it is |
|
|
1398 | relative and your working directory changes, the behaviour is undefined. |
1225 | |
1399 | |
1226 | Since there is no standard to do this, the portable implementation simply |
1400 | Since there is no standard to do this, the portable implementation simply |
1227 | calls C<stat (2)> regularly on the path to see if it changed somehow. You |
1401 | calls C<stat (2)> regularly on the path to see if it changed somehow. You |
1228 | can specify a recommended polling interval for this case. If you specify |
1402 | can specify a recommended polling interval for this case. If you specify |
1229 | a polling interval of C<0> (highly recommended!) then a I<suitable, |
1403 | a polling interval of C<0> (highly recommended!) then a I<suitable, |
… | |
… | |
1241 | reader). Inotify will be used to give hints only and should not change the |
1415 | reader). Inotify will be used to give hints only and should not change the |
1242 | semantics of C<ev_stat> watchers, which means that libev sometimes needs |
1416 | semantics of C<ev_stat> watchers, which means that libev sometimes needs |
1243 | to fall back to regular polling again even with inotify, but changes are |
1417 | to fall back to regular polling again even with inotify, but changes are |
1244 | usually detected immediately, and if the file exists there will be no |
1418 | usually detected immediately, and if the file exists there will be no |
1245 | polling. |
1419 | polling. |
|
|
1420 | |
|
|
1421 | =head3 Watcher-Specific Functions and Data Members |
1246 | |
1422 | |
1247 | =over 4 |
1423 | =over 4 |
1248 | |
1424 | |
1249 | =item ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval) |
1425 | =item ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval) |
1250 | |
1426 | |
… | |
… | |
1314 | ev_stat_start (loop, &passwd); |
1490 | ev_stat_start (loop, &passwd); |
1315 | |
1491 | |
1316 | |
1492 | |
1317 | =head2 C<ev_idle> - when you've got nothing better to do... |
1493 | =head2 C<ev_idle> - when you've got nothing better to do... |
1318 | |
1494 | |
1319 | Idle watchers trigger events when there are no other events are pending |
1495 | Idle watchers trigger events when no other events of the same or higher |
1320 | (prepare, check and other idle watchers do not count). That is, as long |
1496 | priority are pending (prepare, check and other idle watchers do not |
1321 | as your process is busy handling sockets or timeouts (or even signals, |
1497 | count). |
1322 | imagine) it will not be triggered. But when your process is idle all idle |
1498 | |
1323 | watchers are being called again and again, once per event loop iteration - |
1499 | That is, as long as your process is busy handling sockets or timeouts |
|
|
1500 | (or even signals, imagine) of the same or higher priority it will not be |
|
|
1501 | triggered. But when your process is idle (or only lower-priority watchers |
|
|
1502 | are pending), the idle watchers are being called once per event loop |
1324 | until stopped, that is, or your process receives more events and becomes |
1503 | iteration - until stopped, that is, or your process receives more events |
1325 | busy. |
1504 | and becomes busy again with higher priority stuff. |
1326 | |
1505 | |
1327 | The most noteworthy effect is that as long as any idle watchers are |
1506 | The most noteworthy effect is that as long as any idle watchers are |
1328 | active, the process will not block when waiting for new events. |
1507 | active, the process will not block when waiting for new events. |
1329 | |
1508 | |
1330 | Apart from keeping your process non-blocking (which is a useful |
1509 | Apart from keeping your process non-blocking (which is a useful |
1331 | effect on its own sometimes), idle watchers are a good place to do |
1510 | effect on its own sometimes), idle watchers are a good place to do |
1332 | "pseudo-background processing", or delay processing stuff to after the |
1511 | "pseudo-background processing", or delay processing stuff to after the |
1333 | event loop has handled all outstanding events. |
1512 | event loop has handled all outstanding events. |
|
|
1513 | |
|
|
1514 | =head3 Watcher-Specific Functions and Data Members |
1334 | |
1515 | |
1335 | =over 4 |
1516 | =over 4 |
1336 | |
1517 | |
1337 | =item ev_idle_init (ev_signal *, callback) |
1518 | =item ev_idle_init (ev_signal *, callback) |
1338 | |
1519 | |
… | |
… | |
1396 | with priority higher than or equal to the event loop and one coroutine |
1577 | with priority higher than or equal to the event loop and one coroutine |
1397 | of lower priority, but only once, using idle watchers to keep the event |
1578 | of lower priority, but only once, using idle watchers to keep the event |
1398 | loop from blocking if lower-priority coroutines are active, thus mapping |
1579 | loop from blocking if lower-priority coroutines are active, thus mapping |
1399 | low-priority coroutines to idle/background tasks). |
1580 | low-priority coroutines to idle/background tasks). |
1400 | |
1581 | |
|
|
1582 | It is recommended to give C<ev_check> watchers highest (C<EV_MAXPRI>) |
|
|
1583 | priority, to ensure that they are being run before any other watchers |
|
|
1584 | after the poll. Also, C<ev_check> watchers (and C<ev_prepare> watchers, |
|
|
1585 | too) should not activate ("feed") events into libev. While libev fully |
|
|
1586 | supports this, they will be called before other C<ev_check> watchers did |
|
|
1587 | their job. As C<ev_check> watchers are often used to embed other event |
|
|
1588 | loops those other event loops might be in an unusable state until their |
|
|
1589 | C<ev_check> watcher ran (always remind yourself to coexist peacefully with |
|
|
1590 | others). |
|
|
1591 | |
|
|
1592 | =head3 Watcher-Specific Functions and Data Members |
|
|
1593 | |
1401 | =over 4 |
1594 | =over 4 |
1402 | |
1595 | |
1403 | =item ev_prepare_init (ev_prepare *, callback) |
1596 | =item ev_prepare_init (ev_prepare *, callback) |
1404 | |
1597 | |
1405 | =item ev_check_init (ev_check *, callback) |
1598 | =item ev_check_init (ev_check *, callback) |
… | |
… | |
1408 | parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set> |
1601 | parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set> |
1409 | macros, but using them is utterly, utterly and completely pointless. |
1602 | macros, but using them is utterly, utterly and completely pointless. |
1410 | |
1603 | |
1411 | =back |
1604 | =back |
1412 | |
1605 | |
1413 | Example: To include a library such as adns, you would add IO watchers |
1606 | There are a number of principal ways to embed other event loops or modules |
1414 | and a timeout watcher in a prepare handler, as required by libadns, and |
1607 | into libev. Here are some ideas on how to include libadns into libev |
|
|
1608 | (there is a Perl module named C<EV::ADNS> that does this, which you could |
|
|
1609 | use for an actually working example. Another Perl module named C<EV::Glib> |
|
|
1610 | embeds a Glib main context into libev, and finally, C<Glib::EV> embeds EV |
|
|
1611 | into the Glib event loop). |
|
|
1612 | |
|
|
1613 | Method 1: Add IO watchers and a timeout watcher in a prepare handler, |
1415 | in a check watcher, destroy them and call into libadns. What follows is |
1614 | and in a check watcher, destroy them and call into libadns. What follows |
1416 | pseudo-code only of course: |
1615 | is pseudo-code only of course. This requires you to either use a low |
|
|
1616 | priority for the check watcher or use C<ev_clear_pending> explicitly, as |
|
|
1617 | the callbacks for the IO/timeout watchers might not have been called yet. |
1417 | |
1618 | |
1418 | static ev_io iow [nfd]; |
1619 | static ev_io iow [nfd]; |
1419 | static ev_timer tw; |
1620 | static ev_timer tw; |
1420 | |
1621 | |
1421 | static void |
1622 | static void |
1422 | io_cb (ev_loop *loop, ev_io *w, int revents) |
1623 | io_cb (ev_loop *loop, ev_io *w, int revents) |
1423 | { |
1624 | { |
1424 | // set the relevant poll flags |
|
|
1425 | // could also call adns_processreadable etc. here |
|
|
1426 | struct pollfd *fd = (struct pollfd *)w->data; |
|
|
1427 | if (revents & EV_READ ) fd->revents |= fd->events & POLLIN; |
|
|
1428 | if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT; |
|
|
1429 | } |
1625 | } |
1430 | |
1626 | |
1431 | // create io watchers for each fd and a timer before blocking |
1627 | // create io watchers for each fd and a timer before blocking |
1432 | static void |
1628 | static void |
1433 | adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) |
1629 | adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) |
1434 | { |
1630 | { |
1435 | int timeout = 3600000;truct pollfd fds [nfd]; |
1631 | int timeout = 3600000; |
|
|
1632 | struct pollfd fds [nfd]; |
1436 | // actual code will need to loop here and realloc etc. |
1633 | // actual code will need to loop here and realloc etc. |
1437 | adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
1634 | adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
1438 | |
1635 | |
1439 | /* the callback is illegal, but won't be called as we stop during check */ |
1636 | /* the callback is illegal, but won't be called as we stop during check */ |
1440 | ev_timer_init (&tw, 0, timeout * 1e-3); |
1637 | ev_timer_init (&tw, 0, timeout * 1e-3); |
1441 | ev_timer_start (loop, &tw); |
1638 | ev_timer_start (loop, &tw); |
1442 | |
1639 | |
1443 | // create on ev_io per pollfd |
1640 | // create one ev_io per pollfd |
1444 | for (int i = 0; i < nfd; ++i) |
1641 | for (int i = 0; i < nfd; ++i) |
1445 | { |
1642 | { |
1446 | ev_io_init (iow + i, io_cb, fds [i].fd, |
1643 | ev_io_init (iow + i, io_cb, fds [i].fd, |
1447 | ((fds [i].events & POLLIN ? EV_READ : 0) |
1644 | ((fds [i].events & POLLIN ? EV_READ : 0) |
1448 | | (fds [i].events & POLLOUT ? EV_WRITE : 0))); |
1645 | | (fds [i].events & POLLOUT ? EV_WRITE : 0))); |
1449 | |
1646 | |
1450 | fds [i].revents = 0; |
1647 | fds [i].revents = 0; |
1451 | iow [i].data = fds + i; |
|
|
1452 | ev_io_start (loop, iow + i); |
1648 | ev_io_start (loop, iow + i); |
1453 | } |
1649 | } |
1454 | } |
1650 | } |
1455 | |
1651 | |
1456 | // stop all watchers after blocking |
1652 | // stop all watchers after blocking |
… | |
… | |
1458 | adns_check_cb (ev_loop *loop, ev_check *w, int revents) |
1654 | adns_check_cb (ev_loop *loop, ev_check *w, int revents) |
1459 | { |
1655 | { |
1460 | ev_timer_stop (loop, &tw); |
1656 | ev_timer_stop (loop, &tw); |
1461 | |
1657 | |
1462 | for (int i = 0; i < nfd; ++i) |
1658 | for (int i = 0; i < nfd; ++i) |
|
|
1659 | { |
|
|
1660 | // set the relevant poll flags |
|
|
1661 | // could also call adns_processreadable etc. here |
|
|
1662 | struct pollfd *fd = fds + i; |
|
|
1663 | int revents = ev_clear_pending (iow + i); |
|
|
1664 | if (revents & EV_READ ) fd->revents |= fd->events & POLLIN; |
|
|
1665 | if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT; |
|
|
1666 | |
|
|
1667 | // now stop the watcher |
1463 | ev_io_stop (loop, iow + i); |
1668 | ev_io_stop (loop, iow + i); |
|
|
1669 | } |
1464 | |
1670 | |
1465 | adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop)); |
1671 | adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop)); |
|
|
1672 | } |
|
|
1673 | |
|
|
1674 | Method 2: This would be just like method 1, but you run C<adns_afterpoll> |
|
|
1675 | in the prepare watcher and would dispose of the check watcher. |
|
|
1676 | |
|
|
1677 | Method 3: If the module to be embedded supports explicit event |
|
|
1678 | notification (adns does), you can also make use of the actual watcher |
|
|
1679 | callbacks, and only destroy/create the watchers in the prepare watcher. |
|
|
1680 | |
|
|
1681 | static void |
|
|
1682 | timer_cb (EV_P_ ev_timer *w, int revents) |
|
|
1683 | { |
|
|
1684 | adns_state ads = (adns_state)w->data; |
|
|
1685 | update_now (EV_A); |
|
|
1686 | |
|
|
1687 | adns_processtimeouts (ads, &tv_now); |
|
|
1688 | } |
|
|
1689 | |
|
|
1690 | static void |
|
|
1691 | io_cb (EV_P_ ev_io *w, int revents) |
|
|
1692 | { |
|
|
1693 | adns_state ads = (adns_state)w->data; |
|
|
1694 | update_now (EV_A); |
|
|
1695 | |
|
|
1696 | if (revents & EV_READ ) adns_processreadable (ads, w->fd, &tv_now); |
|
|
1697 | if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now); |
|
|
1698 | } |
|
|
1699 | |
|
|
1700 | // do not ever call adns_afterpoll |
|
|
1701 | |
|
|
1702 | Method 4: Do not use a prepare or check watcher because the module you |
|
|
1703 | want to embed is too inflexible to support it. Instead, youc na override |
|
|
1704 | their poll function. The drawback with this solution is that the main |
|
|
1705 | loop is now no longer controllable by EV. The C<Glib::EV> module does |
|
|
1706 | this. |
|
|
1707 | |
|
|
1708 | static gint |
|
|
1709 | event_poll_func (GPollFD *fds, guint nfds, gint timeout) |
|
|
1710 | { |
|
|
1711 | int got_events = 0; |
|
|
1712 | |
|
|
1713 | for (n = 0; n < nfds; ++n) |
|
|
1714 | // create/start io watcher that sets the relevant bits in fds[n] and increment got_events |
|
|
1715 | |
|
|
1716 | if (timeout >= 0) |
|
|
1717 | // create/start timer |
|
|
1718 | |
|
|
1719 | // poll |
|
|
1720 | ev_loop (EV_A_ 0); |
|
|
1721 | |
|
|
1722 | // stop timer again |
|
|
1723 | if (timeout >= 0) |
|
|
1724 | ev_timer_stop (EV_A_ &to); |
|
|
1725 | |
|
|
1726 | // stop io watchers again - their callbacks should have set |
|
|
1727 | for (n = 0; n < nfds; ++n) |
|
|
1728 | ev_io_stop (EV_A_ iow [n]); |
|
|
1729 | |
|
|
1730 | return got_events; |
1466 | } |
1731 | } |
1467 | |
1732 | |
1468 | |
1733 | |
1469 | =head2 C<ev_embed> - when one backend isn't enough... |
1734 | =head2 C<ev_embed> - when one backend isn't enough... |
1470 | |
1735 | |
1471 | This is a rather advanced watcher type that lets you embed one event loop |
1736 | This is a rather advanced watcher type that lets you embed one event loop |
1472 | into another (currently only C<ev_io> events are supported in the embedded |
1737 | into another (currently only C<ev_io> events are supported in the embedded |
1473 | loop, other types of watchers might be handled in a delayed or incorrect |
1738 | loop, other types of watchers might be handled in a delayed or incorrect |
1474 | fashion and must not be used). |
1739 | fashion and must not be used). (See portability notes, below). |
1475 | |
1740 | |
1476 | There are primarily two reasons you would want that: work around bugs and |
1741 | There are primarily two reasons you would want that: work around bugs and |
1477 | prioritise I/O. |
1742 | prioritise I/O. |
1478 | |
1743 | |
1479 | As an example for a bug workaround, the kqueue backend might only support |
1744 | As an example for a bug workaround, the kqueue backend might only support |
… | |
… | |
1534 | ev_embed_start (loop_hi, &embed); |
1799 | ev_embed_start (loop_hi, &embed); |
1535 | } |
1800 | } |
1536 | else |
1801 | else |
1537 | loop_lo = loop_hi; |
1802 | loop_lo = loop_hi; |
1538 | |
1803 | |
|
|
1804 | =head2 Portability notes |
|
|
1805 | |
|
|
1806 | Kqueue is nominally embeddable, but this is broken on all BSDs that I |
|
|
1807 | tried, in various ways. Usually the embedded event loop will simply never |
|
|
1808 | receive events, sometimes it will only trigger a few times, sometimes in a |
|
|
1809 | loop. Epoll is also nominally embeddable, but many Linux kernel versions |
|
|
1810 | will always eport the epoll fd as ready, even when no events are pending. |
|
|
1811 | |
|
|
1812 | While libev allows embedding these backends (they are contained in |
|
|
1813 | C<ev_embeddable_backends ()>), take extreme care that it will actually |
|
|
1814 | work. |
|
|
1815 | |
|
|
1816 | When in doubt, create a dynamic event loop forced to use sockets (this |
|
|
1817 | usually works) and possibly another thread and a pipe or so to report to |
|
|
1818 | your main event loop. |
|
|
1819 | |
|
|
1820 | =head3 Watcher-Specific Functions and Data Members |
|
|
1821 | |
1539 | =over 4 |
1822 | =over 4 |
1540 | |
1823 | |
1541 | =item ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop) |
1824 | =item ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop) |
1542 | |
1825 | |
1543 | =item ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop) |
1826 | =item ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop) |
… | |
… | |
1552 | |
1835 | |
1553 | Make a single, non-blocking sweep over the embedded loop. This works |
1836 | Make a single, non-blocking sweep over the embedded loop. This works |
1554 | similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most |
1837 | similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most |
1555 | apropriate way for embedded loops. |
1838 | apropriate way for embedded loops. |
1556 | |
1839 | |
1557 | =item struct ev_loop *loop [read-only] |
1840 | =item struct ev_loop *other [read-only] |
1558 | |
1841 | |
1559 | The embedded event loop. |
1842 | The embedded event loop. |
1560 | |
1843 | |
1561 | =back |
1844 | =back |
1562 | |
1845 | |
… | |
… | |
1569 | event loop blocks next and before C<ev_check> watchers are being called, |
1852 | event loop blocks next and before C<ev_check> watchers are being called, |
1570 | and only in the child after the fork. If whoever good citizen calling |
1853 | and only in the child after the fork. If whoever good citizen calling |
1571 | C<ev_default_fork> cheats and calls it in the wrong process, the fork |
1854 | C<ev_default_fork> cheats and calls it in the wrong process, the fork |
1572 | handlers will be invoked, too, of course. |
1855 | handlers will be invoked, too, of course. |
1573 | |
1856 | |
|
|
1857 | =head3 Watcher-Specific Functions and Data Members |
|
|
1858 | |
1574 | =over 4 |
1859 | =over 4 |
1575 | |
1860 | |
1576 | =item ev_fork_init (ev_signal *, callback) |
1861 | =item ev_fork_init (ev_signal *, callback) |
1577 | |
1862 | |
1578 | Initialises and configures the fork watcher - it has no parameters of any |
1863 | Initialises and configures the fork watcher - it has no parameters of any |
… | |
… | |
1674 | |
1959 | |
1675 | To use it, |
1960 | To use it, |
1676 | |
1961 | |
1677 | #include <ev++.h> |
1962 | #include <ev++.h> |
1678 | |
1963 | |
1679 | (it is not installed by default). This automatically includes F<ev.h> |
1964 | This automatically includes F<ev.h> and puts all of its definitions (many |
1680 | and puts all of its definitions (many of them macros) into the global |
1965 | of them macros) into the global namespace. All C++ specific things are |
1681 | namespace. All C++ specific things are put into the C<ev> namespace. |
1966 | put into the C<ev> namespace. It should support all the same embedding |
|
|
1967 | options as F<ev.h>, most notably C<EV_MULTIPLICITY>. |
1682 | |
1968 | |
1683 | It should support all the same embedding options as F<ev.h>, most notably |
1969 | Care has been taken to keep the overhead low. The only data member the C++ |
1684 | C<EV_MULTIPLICITY>. |
1970 | classes add (compared to plain C-style watchers) is the event loop pointer |
|
|
1971 | that the watcher is associated with (or no additional members at all if |
|
|
1972 | you disable C<EV_MULTIPLICITY> when embedding libev). |
|
|
1973 | |
|
|
1974 | Currently, functions, and static and non-static member functions can be |
|
|
1975 | used as callbacks. Other types should be easy to add as long as they only |
|
|
1976 | need one additional pointer for context. If you need support for other |
|
|
1977 | types of functors please contact the author (preferably after implementing |
|
|
1978 | it). |
1685 | |
1979 | |
1686 | Here is a list of things available in the C<ev> namespace: |
1980 | Here is a list of things available in the C<ev> namespace: |
1687 | |
1981 | |
1688 | =over 4 |
1982 | =over 4 |
1689 | |
1983 | |
… | |
… | |
1705 | |
1999 | |
1706 | All of those classes have these methods: |
2000 | All of those classes have these methods: |
1707 | |
2001 | |
1708 | =over 4 |
2002 | =over 4 |
1709 | |
2003 | |
1710 | =item ev::TYPE::TYPE (object *, object::method *) |
2004 | =item ev::TYPE::TYPE () |
1711 | |
2005 | |
1712 | =item ev::TYPE::TYPE (object *, object::method *, struct ev_loop *) |
2006 | =item ev::TYPE::TYPE (struct ev_loop *) |
1713 | |
2007 | |
1714 | =item ev::TYPE::~TYPE |
2008 | =item ev::TYPE::~TYPE |
1715 | |
2009 | |
1716 | The constructor takes a pointer to an object and a method pointer to |
2010 | The constructor (optionally) takes an event loop to associate the watcher |
1717 | the event handler callback to call in this class. The constructor calls |
2011 | with. If it is omitted, it will use C<EV_DEFAULT>. |
1718 | C<ev_init> for you, which means you have to call the C<set> method |
2012 | |
1719 | before starting it. If you do not specify a loop then the constructor |
2013 | The constructor calls C<ev_init> for you, which means you have to call the |
1720 | automatically associates the default loop with this watcher. |
2014 | C<set> method before starting it. |
|
|
2015 | |
|
|
2016 | It will not set a callback, however: You have to call the templated C<set> |
|
|
2017 | method to set a callback before you can start the watcher. |
|
|
2018 | |
|
|
2019 | (The reason why you have to use a method is a limitation in C++ which does |
|
|
2020 | not allow explicit template arguments for constructors). |
1721 | |
2021 | |
1722 | The destructor automatically stops the watcher if it is active. |
2022 | The destructor automatically stops the watcher if it is active. |
|
|
2023 | |
|
|
2024 | =item w->set<class, &class::method> (object *) |
|
|
2025 | |
|
|
2026 | This method sets the callback method to call. The method has to have a |
|
|
2027 | signature of C<void (*)(ev_TYPE &, int)>, it receives the watcher as |
|
|
2028 | first argument and the C<revents> as second. The object must be given as |
|
|
2029 | parameter and is stored in the C<data> member of the watcher. |
|
|
2030 | |
|
|
2031 | This method synthesizes efficient thunking code to call your method from |
|
|
2032 | the C callback that libev requires. If your compiler can inline your |
|
|
2033 | callback (i.e. it is visible to it at the place of the C<set> call and |
|
|
2034 | your compiler is good :), then the method will be fully inlined into the |
|
|
2035 | thunking function, making it as fast as a direct C callback. |
|
|
2036 | |
|
|
2037 | Example: simple class declaration and watcher initialisation |
|
|
2038 | |
|
|
2039 | struct myclass |
|
|
2040 | { |
|
|
2041 | void io_cb (ev::io &w, int revents) { } |
|
|
2042 | } |
|
|
2043 | |
|
|
2044 | myclass obj; |
|
|
2045 | ev::io iow; |
|
|
2046 | iow.set <myclass, &myclass::io_cb> (&obj); |
|
|
2047 | |
|
|
2048 | =item w->set<function> (void *data = 0) |
|
|
2049 | |
|
|
2050 | Also sets a callback, but uses a static method or plain function as |
|
|
2051 | callback. The optional C<data> argument will be stored in the watcher's |
|
|
2052 | C<data> member and is free for you to use. |
|
|
2053 | |
|
|
2054 | The prototype of the C<function> must be C<void (*)(ev::TYPE &w, int)>. |
|
|
2055 | |
|
|
2056 | See the method-C<set> above for more details. |
|
|
2057 | |
|
|
2058 | Example: |
|
|
2059 | |
|
|
2060 | static void io_cb (ev::io &w, int revents) { } |
|
|
2061 | iow.set <io_cb> (); |
1723 | |
2062 | |
1724 | =item w->set (struct ev_loop *) |
2063 | =item w->set (struct ev_loop *) |
1725 | |
2064 | |
1726 | Associates a different C<struct ev_loop> with this watcher. You can only |
2065 | Associates a different C<struct ev_loop> with this watcher. You can only |
1727 | do this when the watcher is inactive (and not pending either). |
2066 | do this when the watcher is inactive (and not pending either). |
1728 | |
2067 | |
1729 | =item w->set ([args]) |
2068 | =item w->set ([args]) |
1730 | |
2069 | |
1731 | Basically the same as C<ev_TYPE_set>, with the same args. Must be |
2070 | Basically the same as C<ev_TYPE_set>, with the same args. Must be |
1732 | called at least once. Unlike the C counterpart, an active watcher gets |
2071 | called at least once. Unlike the C counterpart, an active watcher gets |
1733 | automatically stopped and restarted. |
2072 | automatically stopped and restarted when reconfiguring it with this |
|
|
2073 | method. |
1734 | |
2074 | |
1735 | =item w->start () |
2075 | =item w->start () |
1736 | |
2076 | |
1737 | Starts the watcher. Note that there is no C<loop> argument as the |
2077 | Starts the watcher. Note that there is no C<loop> argument, as the |
1738 | constructor already takes the loop. |
2078 | constructor already stores the event loop. |
1739 | |
2079 | |
1740 | =item w->stop () |
2080 | =item w->stop () |
1741 | |
2081 | |
1742 | Stops the watcher if it is active. Again, no C<loop> argument. |
2082 | Stops the watcher if it is active. Again, no C<loop> argument. |
1743 | |
2083 | |
1744 | =item w->again () C<ev::timer>, C<ev::periodic> only |
2084 | =item w->again () (C<ev::timer>, C<ev::periodic> only) |
1745 | |
2085 | |
1746 | For C<ev::timer> and C<ev::periodic>, this invokes the corresponding |
2086 | For C<ev::timer> and C<ev::periodic>, this invokes the corresponding |
1747 | C<ev_TYPE_again> function. |
2087 | C<ev_TYPE_again> function. |
1748 | |
2088 | |
1749 | =item w->sweep () C<ev::embed> only |
2089 | =item w->sweep () (C<ev::embed> only) |
1750 | |
2090 | |
1751 | Invokes C<ev_embed_sweep>. |
2091 | Invokes C<ev_embed_sweep>. |
1752 | |
2092 | |
1753 | =item w->update () C<ev::stat> only |
2093 | =item w->update () (C<ev::stat> only) |
1754 | |
2094 | |
1755 | Invokes C<ev_stat_stat>. |
2095 | Invokes C<ev_stat_stat>. |
1756 | |
2096 | |
1757 | =back |
2097 | =back |
1758 | |
2098 | |
… | |
… | |
1768 | |
2108 | |
1769 | myclass (); |
2109 | myclass (); |
1770 | } |
2110 | } |
1771 | |
2111 | |
1772 | myclass::myclass (int fd) |
2112 | myclass::myclass (int fd) |
1773 | : io (this, &myclass::io_cb), |
|
|
1774 | idle (this, &myclass::idle_cb) |
|
|
1775 | { |
2113 | { |
|
|
2114 | io .set <myclass, &myclass::io_cb > (this); |
|
|
2115 | idle.set <myclass, &myclass::idle_cb> (this); |
|
|
2116 | |
1776 | io.start (fd, ev::READ); |
2117 | io.start (fd, ev::READ); |
1777 | } |
2118 | } |
1778 | |
2119 | |
1779 | |
2120 | |
1780 | =head1 MACRO MAGIC |
2121 | =head1 MACRO MAGIC |
1781 | |
2122 | |
1782 | Libev can be compiled with a variety of options, the most fundemantal is |
2123 | Libev can be compiled with a variety of options, the most fundamantal |
1783 | C<EV_MULTIPLICITY>. This option determines wether (most) functions and |
2124 | of which is C<EV_MULTIPLICITY>. This option determines whether (most) |
1784 | callbacks have an initial C<struct ev_loop *> argument. |
2125 | functions and callbacks have an initial C<struct ev_loop *> argument. |
1785 | |
2126 | |
1786 | To make it easier to write programs that cope with either variant, the |
2127 | To make it easier to write programs that cope with either variant, the |
1787 | following macros are defined: |
2128 | following macros are defined: |
1788 | |
2129 | |
1789 | =over 4 |
2130 | =over 4 |
… | |
… | |
1821 | Similar to the other two macros, this gives you the value of the default |
2162 | Similar to the other two macros, this gives you the value of the default |
1822 | loop, if multiple loops are supported ("ev loop default"). |
2163 | loop, if multiple loops are supported ("ev loop default"). |
1823 | |
2164 | |
1824 | =back |
2165 | =back |
1825 | |
2166 | |
1826 | Example: Declare and initialise a check watcher, working regardless of |
2167 | Example: Declare and initialise a check watcher, utilising the above |
1827 | wether multiple loops are supported or not. |
2168 | macros so it will work regardless of whether multiple loops are supported |
|
|
2169 | or not. |
1828 | |
2170 | |
1829 | static void |
2171 | static void |
1830 | check_cb (EV_P_ ev_timer *w, int revents) |
2172 | check_cb (EV_P_ ev_timer *w, int revents) |
1831 | { |
2173 | { |
1832 | ev_check_stop (EV_A_ w); |
2174 | ev_check_stop (EV_A_ w); |
… | |
… | |
1835 | ev_check check; |
2177 | ev_check check; |
1836 | ev_check_init (&check, check_cb); |
2178 | ev_check_init (&check, check_cb); |
1837 | ev_check_start (EV_DEFAULT_ &check); |
2179 | ev_check_start (EV_DEFAULT_ &check); |
1838 | ev_loop (EV_DEFAULT_ 0); |
2180 | ev_loop (EV_DEFAULT_ 0); |
1839 | |
2181 | |
1840 | |
|
|
1841 | =head1 EMBEDDING |
2182 | =head1 EMBEDDING |
1842 | |
2183 | |
1843 | Libev can (and often is) directly embedded into host |
2184 | Libev can (and often is) directly embedded into host |
1844 | applications. Examples of applications that embed it include the Deliantra |
2185 | applications. Examples of applications that embed it include the Deliantra |
1845 | Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe) |
2186 | Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe) |
1846 | and rxvt-unicode. |
2187 | and rxvt-unicode. |
1847 | |
2188 | |
1848 | The goal is to enable you to just copy the neecssary files into your |
2189 | The goal is to enable you to just copy the necessary files into your |
1849 | source directory without having to change even a single line in them, so |
2190 | source directory without having to change even a single line in them, so |
1850 | you can easily upgrade by simply copying (or having a checked-out copy of |
2191 | you can easily upgrade by simply copying (or having a checked-out copy of |
1851 | libev somewhere in your source tree). |
2192 | libev somewhere in your source tree). |
1852 | |
2193 | |
1853 | =head2 FILESETS |
2194 | =head2 FILESETS |
… | |
… | |
1884 | ev_vars.h |
2225 | ev_vars.h |
1885 | ev_wrap.h |
2226 | ev_wrap.h |
1886 | |
2227 | |
1887 | ev_win32.c required on win32 platforms only |
2228 | ev_win32.c required on win32 platforms only |
1888 | |
2229 | |
1889 | ev_select.c only when select backend is enabled (which is by default) |
2230 | ev_select.c only when select backend is enabled (which is enabled by default) |
1890 | ev_poll.c only when poll backend is enabled (disabled by default) |
2231 | ev_poll.c only when poll backend is enabled (disabled by default) |
1891 | ev_epoll.c only when the epoll backend is enabled (disabled by default) |
2232 | ev_epoll.c only when the epoll backend is enabled (disabled by default) |
1892 | ev_kqueue.c only when the kqueue backend is enabled (disabled by default) |
2233 | ev_kqueue.c only when the kqueue backend is enabled (disabled by default) |
1893 | ev_port.c only when the solaris port backend is enabled (disabled by default) |
2234 | ev_port.c only when the solaris port backend is enabled (disabled by default) |
1894 | |
2235 | |
… | |
… | |
1943 | |
2284 | |
1944 | If defined to be C<1>, libev will try to detect the availability of the |
2285 | If defined to be C<1>, libev will try to detect the availability of the |
1945 | monotonic clock option at both compiletime and runtime. Otherwise no use |
2286 | monotonic clock option at both compiletime and runtime. Otherwise no use |
1946 | of the monotonic clock option will be attempted. If you enable this, you |
2287 | of the monotonic clock option will be attempted. If you enable this, you |
1947 | usually have to link against librt or something similar. Enabling it when |
2288 | usually have to link against librt or something similar. Enabling it when |
1948 | the functionality isn't available is safe, though, althoguh you have |
2289 | the functionality isn't available is safe, though, although you have |
1949 | to make sure you link against any libraries where the C<clock_gettime> |
2290 | to make sure you link against any libraries where the C<clock_gettime> |
1950 | function is hiding in (often F<-lrt>). |
2291 | function is hiding in (often F<-lrt>). |
1951 | |
2292 | |
1952 | =item EV_USE_REALTIME |
2293 | =item EV_USE_REALTIME |
1953 | |
2294 | |
1954 | If defined to be C<1>, libev will try to detect the availability of the |
2295 | If defined to be C<1>, libev will try to detect the availability of the |
1955 | realtime clock option at compiletime (and assume its availability at |
2296 | realtime clock option at compiletime (and assume its availability at |
1956 | runtime if successful). Otherwise no use of the realtime clock option will |
2297 | runtime if successful). Otherwise no use of the realtime clock option will |
1957 | be attempted. This effectively replaces C<gettimeofday> by C<clock_get |
2298 | be attempted. This effectively replaces C<gettimeofday> by C<clock_get |
1958 | (CLOCK_REALTIME, ...)> and will not normally affect correctness. See tzhe note about libraries |
2299 | (CLOCK_REALTIME, ...)> and will not normally affect correctness. See the |
1959 | in the description of C<EV_USE_MONOTONIC>, though. |
2300 | note about libraries in the description of C<EV_USE_MONOTONIC>, though. |
1960 | |
2301 | |
1961 | =item EV_USE_SELECT |
2302 | =item EV_USE_SELECT |
1962 | |
2303 | |
1963 | If undefined or defined to be C<1>, libev will compile in support for the |
2304 | If undefined or defined to be C<1>, libev will compile in support for the |
1964 | C<select>(2) backend. No attempt at autodetection will be done: if no |
2305 | C<select>(2) backend. No attempt at autodetection will be done: if no |
… | |
… | |
2057 | will have the C<struct ev_loop *> as first argument, and you can create |
2398 | will have the C<struct ev_loop *> as first argument, and you can create |
2058 | additional independent event loops. Otherwise there will be no support |
2399 | additional independent event loops. Otherwise there will be no support |
2059 | for multiple event loops and there is no first event loop pointer |
2400 | for multiple event loops and there is no first event loop pointer |
2060 | argument. Instead, all functions act on the single default loop. |
2401 | argument. Instead, all functions act on the single default loop. |
2061 | |
2402 | |
|
|
2403 | =item EV_MINPRI |
|
|
2404 | |
|
|
2405 | =item EV_MAXPRI |
|
|
2406 | |
|
|
2407 | The range of allowed priorities. C<EV_MINPRI> must be smaller or equal to |
|
|
2408 | C<EV_MAXPRI>, but otherwise there are no non-obvious limitations. You can |
|
|
2409 | provide for more priorities by overriding those symbols (usually defined |
|
|
2410 | to be C<-2> and C<2>, respectively). |
|
|
2411 | |
|
|
2412 | When doing priority-based operations, libev usually has to linearly search |
|
|
2413 | all the priorities, so having many of them (hundreds) uses a lot of space |
|
|
2414 | and time, so using the defaults of five priorities (-2 .. +2) is usually |
|
|
2415 | fine. |
|
|
2416 | |
|
|
2417 | If your embedding app does not need any priorities, defining these both to |
|
|
2418 | C<0> will save some memory and cpu. |
|
|
2419 | |
2062 | =item EV_PERIODIC_ENABLE |
2420 | =item EV_PERIODIC_ENABLE |
2063 | |
2421 | |
2064 | If undefined or defined to be C<1>, then periodic timers are supported. If |
2422 | If undefined or defined to be C<1>, then periodic timers are supported. If |
|
|
2423 | defined to be C<0>, then they are not. Disabling them saves a few kB of |
|
|
2424 | code. |
|
|
2425 | |
|
|
2426 | =item EV_IDLE_ENABLE |
|
|
2427 | |
|
|
2428 | If undefined or defined to be C<1>, then idle watchers are supported. If |
2065 | defined to be C<0>, then they are not. Disabling them saves a few kB of |
2429 | defined to be C<0>, then they are not. Disabling them saves a few kB of |
2066 | code. |
2430 | code. |
2067 | |
2431 | |
2068 | =item EV_EMBED_ENABLE |
2432 | =item EV_EMBED_ENABLE |
2069 | |
2433 | |
… | |
… | |
2120 | |
2484 | |
2121 | =item ev_set_cb (ev, cb) |
2485 | =item ev_set_cb (ev, cb) |
2122 | |
2486 | |
2123 | Can be used to change the callback member declaration in each watcher, |
2487 | Can be used to change the callback member declaration in each watcher, |
2124 | and the way callbacks are invoked and set. Must expand to a struct member |
2488 | and the way callbacks are invoked and set. Must expand to a struct member |
2125 | definition and a statement, respectively. See the F<ev.v> header file for |
2489 | definition and a statement, respectively. See the F<ev.h> header file for |
2126 | their default definitions. One possible use for overriding these is to |
2490 | their default definitions. One possible use for overriding these is to |
2127 | avoid the C<struct ev_loop *> as first argument in all cases, or to use |
2491 | avoid the C<struct ev_loop *> as first argument in all cases, or to use |
2128 | method calls instead of plain function calls in C++. |
2492 | method calls instead of plain function calls in C++. |
|
|
2493 | |
|
|
2494 | =head2 EXPORTED API SYMBOLS |
|
|
2495 | |
|
|
2496 | If you need to re-export the API (e.g. via a dll) and you need a list of |
|
|
2497 | exported symbols, you can use the provided F<Symbol.*> files which list |
|
|
2498 | all public symbols, one per line: |
|
|
2499 | |
|
|
2500 | Symbols.ev for libev proper |
|
|
2501 | Symbols.event for the libevent emulation |
|
|
2502 | |
|
|
2503 | This can also be used to rename all public symbols to avoid clashes with |
|
|
2504 | multiple versions of libev linked together (which is obviously bad in |
|
|
2505 | itself, but sometimes it is inconvinient to avoid this). |
|
|
2506 | |
|
|
2507 | A sed command like this will create wrapper C<#define>'s that you need to |
|
|
2508 | include before including F<ev.h>: |
|
|
2509 | |
|
|
2510 | <Symbols.ev sed -e "s/.*/#define & myprefix_&/" >wrap.h |
|
|
2511 | |
|
|
2512 | This would create a file F<wrap.h> which essentially looks like this: |
|
|
2513 | |
|
|
2514 | #define ev_backend myprefix_ev_backend |
|
|
2515 | #define ev_check_start myprefix_ev_check_start |
|
|
2516 | #define ev_check_stop myprefix_ev_check_stop |
|
|
2517 | ... |
2129 | |
2518 | |
2130 | =head2 EXAMPLES |
2519 | =head2 EXAMPLES |
2131 | |
2520 | |
2132 | For a real-world example of a program the includes libev |
2521 | For a real-world example of a program the includes libev |
2133 | verbatim, you can have a look at the EV perl module |
2522 | verbatim, you can have a look at the EV perl module |
… | |
… | |
2136 | interface) and F<EV.xs> (implementation) files. Only the F<EV.xs> file |
2525 | interface) and F<EV.xs> (implementation) files. Only the F<EV.xs> file |
2137 | will be compiled. It is pretty complex because it provides its own header |
2526 | will be compiled. It is pretty complex because it provides its own header |
2138 | file. |
2527 | file. |
2139 | |
2528 | |
2140 | The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file |
2529 | The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file |
2141 | that everybody includes and which overrides some autoconf choices: |
2530 | that everybody includes and which overrides some configure choices: |
2142 | |
2531 | |
|
|
2532 | #define EV_MINIMAL 1 |
2143 | #define EV_USE_POLL 0 |
2533 | #define EV_USE_POLL 0 |
2144 | #define EV_MULTIPLICITY 0 |
2534 | #define EV_MULTIPLICITY 0 |
2145 | #define EV_PERIODICS 0 |
2535 | #define EV_PERIODIC_ENABLE 0 |
|
|
2536 | #define EV_STAT_ENABLE 0 |
|
|
2537 | #define EV_FORK_ENABLE 0 |
2146 | #define EV_CONFIG_H <config.h> |
2538 | #define EV_CONFIG_H <config.h> |
|
|
2539 | #define EV_MINPRI 0 |
|
|
2540 | #define EV_MAXPRI 0 |
2147 | |
2541 | |
2148 | #include "ev++.h" |
2542 | #include "ev++.h" |
2149 | |
2543 | |
2150 | And a F<ev_cpp.C> implementation file that contains libev proper and is compiled: |
2544 | And a F<ev_cpp.C> implementation file that contains libev proper and is compiled: |
2151 | |
2545 | |
… | |
… | |
2157 | |
2551 | |
2158 | In this section the complexities of (many of) the algorithms used inside |
2552 | In this section the complexities of (many of) the algorithms used inside |
2159 | libev will be explained. For complexity discussions about backends see the |
2553 | libev will be explained. For complexity discussions about backends see the |
2160 | documentation for C<ev_default_init>. |
2554 | documentation for C<ev_default_init>. |
2161 | |
2555 | |
|
|
2556 | All of the following are about amortised time: If an array needs to be |
|
|
2557 | extended, libev needs to realloc and move the whole array, but this |
|
|
2558 | happens asymptotically never with higher number of elements, so O(1) might |
|
|
2559 | mean it might do a lengthy realloc operation in rare cases, but on average |
|
|
2560 | it is much faster and asymptotically approaches constant time. |
|
|
2561 | |
2162 | =over 4 |
2562 | =over 4 |
2163 | |
2563 | |
2164 | =item Starting and stopping timer/periodic watchers: O(log skipped_other_timers) |
2564 | =item Starting and stopping timer/periodic watchers: O(log skipped_other_timers) |
2165 | |
2565 | |
|
|
2566 | This means that, when you have a watcher that triggers in one hour and |
|
|
2567 | there are 100 watchers that would trigger before that then inserting will |
|
|
2568 | have to skip those 100 watchers. |
|
|
2569 | |
2166 | =item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers) |
2570 | =item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers) |
2167 | |
2571 | |
|
|
2572 | That means that for changing a timer costs less than removing/adding them |
|
|
2573 | as only the relative motion in the event queue has to be paid for. |
|
|
2574 | |
2168 | =item Starting io/check/prepare/idle/signal/child watchers: O(1) |
2575 | =item Starting io/check/prepare/idle/signal/child watchers: O(1) |
2169 | |
2576 | |
|
|
2577 | These just add the watcher into an array or at the head of a list. |
2170 | =item Stopping check/prepare/idle watchers: O(1) |
2578 | =item Stopping check/prepare/idle watchers: O(1) |
2171 | |
2579 | |
2172 | =item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE)) |
2580 | =item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE)) |
2173 | |
2581 | |
|
|
2582 | These watchers are stored in lists then need to be walked to find the |
|
|
2583 | correct watcher to remove. The lists are usually short (you don't usually |
|
|
2584 | have many watchers waiting for the same fd or signal). |
|
|
2585 | |
2174 | =item Finding the next timer per loop iteration: O(1) |
2586 | =item Finding the next timer per loop iteration: O(1) |
2175 | |
2587 | |
2176 | =item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd) |
2588 | =item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd) |
2177 | |
2589 | |
|
|
2590 | A change means an I/O watcher gets started or stopped, which requires |
|
|
2591 | libev to recalculate its status (and possibly tell the kernel). |
|
|
2592 | |
2178 | =item Activating one watcher: O(1) |
2593 | =item Activating one watcher: O(1) |
2179 | |
2594 | |
|
|
2595 | =item Priority handling: O(number_of_priorities) |
|
|
2596 | |
|
|
2597 | Priorities are implemented by allocating some space for each |
|
|
2598 | priority. When doing priority-based operations, libev usually has to |
|
|
2599 | linearly search all the priorities. |
|
|
2600 | |
2180 | =back |
2601 | =back |
2181 | |
2602 | |
2182 | |
2603 | |
2183 | =head1 AUTHOR |
2604 | =head1 AUTHOR |
2184 | |
2605 | |