… | |
… | |
56 | |
56 | |
57 | =over 4 |
57 | =over 4 |
58 | |
58 | |
59 | =item ev_tstamp ev_time () |
59 | =item ev_tstamp ev_time () |
60 | |
60 | |
61 | Returns the current time as libev would use it. |
61 | Returns the current time as libev would use it. Please note that the |
|
|
62 | C<ev_now> function is usually faster and also often returns the timestamp |
|
|
63 | you actually want to know. |
62 | |
64 | |
63 | =item int ev_version_major () |
65 | =item int ev_version_major () |
64 | |
66 | |
65 | =item int ev_version_minor () |
67 | =item int ev_version_minor () |
66 | |
68 | |
… | |
… | |
143 | C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will |
145 | C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will |
144 | override the flags completely if it is found in the environment. This is |
146 | override the flags completely if it is found in the environment. This is |
145 | useful to try out specific backends to test their performance, or to work |
147 | useful to try out specific backends to test their performance, or to work |
146 | around bugs. |
148 | around bugs. |
147 | |
149 | |
148 | =item C<EVMETHOD_SELECT> (portable select backend) |
150 | =item C<EVMETHOD_SELECT> (value 1, portable select backend) |
149 | |
151 | |
|
|
152 | This is your standard select(2) backend. Not I<completely> standard, as |
|
|
153 | libev tries to roll its own fd_set with no limits on the number of fds, |
|
|
154 | but if that fails, expect a fairly low limit on the number of fds when |
|
|
155 | using this backend. It doesn't scale too well (O(highest_fd)), but its usually |
|
|
156 | the fastest backend for a low number of fds. |
|
|
157 | |
150 | =item C<EVMETHOD_POLL> (poll backend, available everywhere except on windows) |
158 | =item C<EVMETHOD_POLL> (value 2, poll backend, available everywhere except on windows) |
151 | |
159 | |
|
|
160 | And this is your standard poll(2) backend. It's more complicated than |
|
|
161 | select, but handles sparse fds better and has no artificial limit on the |
|
|
162 | number of fds you can use (except it will slow down considerably with a |
|
|
163 | lot of inactive fds). It scales similarly to select, i.e. O(total_fds). |
|
|
164 | |
152 | =item C<EVMETHOD_EPOLL> (linux only) |
165 | =item C<EVMETHOD_EPOLL> (value 4, Linux) |
153 | |
166 | |
154 | =item C<EVMETHOD_KQUEUE> (some bsds only) |
167 | For few fds, this backend is a bit little slower than poll and select, |
|
|
168 | but it scales phenomenally better. While poll and select usually scale like |
|
|
169 | O(total_fds) where n is the total number of fds (or the highest fd), epoll scales |
|
|
170 | either O(1) or O(active_fds). |
155 | |
171 | |
|
|
172 | While stopping and starting an I/O watcher in the same iteration will |
|
|
173 | result in some caching, there is still a syscall per such incident |
|
|
174 | (because the fd could point to a different file description now), so its |
|
|
175 | best to avoid that. Also, dup()ed file descriptors might not work very |
|
|
176 | well if you register events for both fds. |
|
|
177 | |
|
|
178 | =item C<EVMETHOD_KQUEUE> (value 8, most BSD clones) |
|
|
179 | |
|
|
180 | Kqueue deserves special mention, as at the time of this writing, it |
|
|
181 | was broken on all BSDs except NetBSD (usually it doesn't work with |
|
|
182 | anything but sockets and pipes, except on Darwin, where of course its |
|
|
183 | completely useless). For this reason its not being "autodetected" unless |
|
|
184 | you explicitly specify the flags (i.e. you don't use EVFLAG_AUTO). |
|
|
185 | |
|
|
186 | It scales in the same way as the epoll backend, but the interface to the |
|
|
187 | kernel is more efficient (which says nothing about its actual speed, of |
|
|
188 | course). While starting and stopping an I/O watcher does not cause an |
|
|
189 | extra syscall as with epoll, it still adds up to four event changes per |
|
|
190 | incident, so its best to avoid that. |
|
|
191 | |
156 | =item C<EVMETHOD_DEVPOLL> (solaris 8 only) |
192 | =item C<EVMETHOD_DEVPOLL> (value 16, Solaris 8) |
157 | |
193 | |
|
|
194 | This is not implemented yet (and might never be). |
|
|
195 | |
158 | =item C<EVMETHOD_PORT> (solaris 10 only) |
196 | =item C<EVMETHOD_PORT> (value 32, Solaris 10) |
|
|
197 | |
|
|
198 | This uses the Solaris 10 port mechanism. As with everything on Solaris, |
|
|
199 | it's really slow, but it still scales very well (O(active_fds)). |
|
|
200 | |
|
|
201 | =item C<EVMETHOD_ALL> |
|
|
202 | |
|
|
203 | Try all backends (even potentially broken ones that wouldn't be tried |
|
|
204 | with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as |
|
|
205 | C<EVMETHOD_ALL & ~EVMETHOD_KQUEUE>. |
|
|
206 | |
|
|
207 | =back |
159 | |
208 | |
160 | If one or more of these are ored into the flags value, then only these |
209 | If one or more of these are ored into the flags value, then only these |
161 | backends will be tried (in the reverse order as given here). If one are |
210 | backends will be tried (in the reverse order as given here). If none are |
162 | specified, any backend will do. |
211 | specified, most compiled-in backend will be tried, usually in reverse |
163 | |
212 | order of their flag values :) |
164 | =back |
|
|
165 | |
213 | |
166 | =item struct ev_loop *ev_loop_new (unsigned int flags) |
214 | =item struct ev_loop *ev_loop_new (unsigned int flags) |
167 | |
215 | |
168 | Similar to C<ev_default_loop>, but always creates a new event loop that is |
216 | Similar to C<ev_default_loop>, but always creates a new event loop that is |
169 | always distinct from the default loop. Unlike the default loop, it cannot |
217 | always distinct from the default loop. Unlike the default loop, it cannot |
… | |
… | |
186 | This function reinitialises the kernel state for backends that have |
234 | This function reinitialises the kernel state for backends that have |
187 | one. Despite the name, you can call it anytime, but it makes most sense |
235 | one. Despite the name, you can call it anytime, but it makes most sense |
188 | after forking, in either the parent or child process (or both, but that |
236 | after forking, in either the parent or child process (or both, but that |
189 | again makes little sense). |
237 | again makes little sense). |
190 | |
238 | |
191 | You I<must> call this function after forking if and only if you want to |
239 | You I<must> call this function in the child process after forking if and |
192 | use the event library in both processes. If you just fork+exec, you don't |
240 | only if you want to use the event library in both processes. If you just |
193 | have to call it. |
241 | fork+exec, you don't have to call it. |
194 | |
242 | |
195 | The function itself is quite fast and it's usually not a problem to call |
243 | The function itself is quite fast and it's usually not a problem to call |
196 | it just in case after a fork. To make this easy, the function will fit in |
244 | it just in case after a fork. To make this easy, the function will fit in |
197 | quite nicely into a call to C<pthread_atfork>: |
245 | quite nicely into a call to C<pthread_atfork>: |
198 | |
246 | |
… | |
… | |
237 | |
285 | |
238 | This flags value could be used to implement alternative looping |
286 | This flags value could be used to implement alternative looping |
239 | constructs, but the C<prepare> and C<check> watchers provide a better and |
287 | constructs, but the C<prepare> and C<check> watchers provide a better and |
240 | more generic mechanism. |
288 | more generic mechanism. |
241 | |
289 | |
|
|
290 | Here are the gory details of what ev_loop does: |
|
|
291 | |
|
|
292 | 1. If there are no active watchers (reference count is zero), return. |
|
|
293 | 2. Queue and immediately call all prepare watchers. |
|
|
294 | 3. If we have been forked, recreate the kernel state. |
|
|
295 | 4. Update the kernel state with all outstanding changes. |
|
|
296 | 5. Update the "event loop time". |
|
|
297 | 6. Calculate for how long to block. |
|
|
298 | 7. Block the process, waiting for events. |
|
|
299 | 8. Update the "event loop time" and do time jump handling. |
|
|
300 | 9. Queue all outstanding timers. |
|
|
301 | 10. Queue all outstanding periodics. |
|
|
302 | 11. If no events are pending now, queue all idle watchers. |
|
|
303 | 12. Queue all check watchers. |
|
|
304 | 13. Call all queued watchers in reverse order (i.e. check watchers first). |
|
|
305 | 14. If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
|
|
306 | was used, return, otherwise continue with step #1. |
|
|
307 | |
242 | =item ev_unloop (loop, how) |
308 | =item ev_unloop (loop, how) |
243 | |
309 | |
244 | Can be used to make a call to C<ev_loop> return early (but only after it |
310 | Can be used to make a call to C<ev_loop> return early (but only after it |
245 | has processed all outstanding events). The C<how> argument must be either |
311 | has processed all outstanding events). The C<how> argument must be either |
246 | C<EVUNLOOP_ONCE>, which will make the innermost C<ev_loop> call return, or |
312 | C<EVUNLOOP_ONE>, which will make the innermost C<ev_loop> call return, or |
247 | C<EVUNLOOP_ALL>, which will make all nested C<ev_loop> calls return. |
313 | C<EVUNLOOP_ALL>, which will make all nested C<ev_loop> calls return. |
248 | |
314 | |
249 | =item ev_ref (loop) |
315 | =item ev_ref (loop) |
250 | |
316 | |
251 | =item ev_unref (loop) |
317 | =item ev_unref (loop) |
… | |
… | |
417 | in each iteration of the event loop (This behaviour is called |
483 | in each iteration of the event loop (This behaviour is called |
418 | level-triggering because you keep receiving events as long as the |
484 | level-triggering because you keep receiving events as long as the |
419 | condition persists. Remember you can stop the watcher if you don't want to |
485 | condition persists. Remember you can stop the watcher if you don't want to |
420 | act on the event and neither want to receive future events). |
486 | act on the event and neither want to receive future events). |
421 | |
487 | |
422 | In general you can register as many read and/or write event watchers oer |
488 | In general you can register as many read and/or write event watchers per |
423 | fd as you want (as long as you don't confuse yourself). Setting all file |
489 | fd as you want (as long as you don't confuse yourself). Setting all file |
424 | descriptors to non-blocking mode is also usually a good idea (but not |
490 | descriptors to non-blocking mode is also usually a good idea (but not |
425 | required if you know what you are doing). |
491 | required if you know what you are doing). |
426 | |
492 | |
427 | You have to be careful with dup'ed file descriptors, though. Some backends |
493 | You have to be careful with dup'ed file descriptors, though. Some backends |
428 | (the linux epoll backend is a notable example) cannot handle dup'ed file |
494 | (the linux epoll backend is a notable example) cannot handle dup'ed file |
429 | descriptors correctly if you register interest in two or more fds pointing |
495 | descriptors correctly if you register interest in two or more fds pointing |
430 | to the same file/socket etc. description. |
496 | to the same underlying file/socket etc. description (that is, they share |
|
|
497 | the same underlying "file open"). |
431 | |
498 | |
432 | If you must do this, then force the use of a known-to-be-good backend |
499 | If you must do this, then force the use of a known-to-be-good backend |
433 | (at the time of this writing, this includes only EVMETHOD_SELECT and |
500 | (at the time of this writing, this includes only EVMETHOD_SELECT and |
434 | EVMETHOD_POLL). |
501 | EVMETHOD_POLL). |
435 | |
502 | |
… | |
… | |
449 | |
516 | |
450 | Timer watchers are simple relative timers that generate an event after a |
517 | Timer watchers are simple relative timers that generate an event after a |
451 | given time, and optionally repeating in regular intervals after that. |
518 | given time, and optionally repeating in regular intervals after that. |
452 | |
519 | |
453 | The timers are based on real time, that is, if you register an event that |
520 | The timers are based on real time, that is, if you register an event that |
454 | times out after an hour and youreset your system clock to last years |
521 | times out after an hour and you reset your system clock to last years |
455 | time, it will still time out after (roughly) and hour. "Roughly" because |
522 | time, it will still time out after (roughly) and hour. "Roughly" because |
456 | detecting time jumps is hard, and soem inaccuracies are unavoidable (the |
523 | detecting time jumps is hard, and some inaccuracies are unavoidable (the |
457 | monotonic clock option helps a lot here). |
524 | monotonic clock option helps a lot here). |
458 | |
525 | |
459 | The relative timeouts are calculated relative to the C<ev_now ()> |
526 | The relative timeouts are calculated relative to the C<ev_now ()> |
460 | time. This is usually the right thing as this timestamp refers to the time |
527 | time. This is usually the right thing as this timestamp refers to the time |
461 | of the event triggering whatever timeout you are modifying/starting. If |
528 | of the event triggering whatever timeout you are modifying/starting. If |
462 | you suspect event processing to be delayed and you *need* to base the timeout |
529 | you suspect event processing to be delayed and you I<need> to base the timeout |
463 | ion the current time, use something like this to adjust for this: |
530 | on the current time, use something like this to adjust for this: |
464 | |
531 | |
465 | ev_timer_set (&timer, after + ev_now () - ev_time (), 0.); |
532 | ev_timer_set (&timer, after + ev_now () - ev_time (), 0.); |
|
|
533 | |
|
|
534 | The callback is guarenteed to be invoked only when its timeout has passed, |
|
|
535 | but if multiple timers become ready during the same loop iteration then |
|
|
536 | order of execution is undefined. |
466 | |
537 | |
467 | =over 4 |
538 | =over 4 |
468 | |
539 | |
469 | =item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat) |
540 | =item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat) |
470 | |
541 | |
… | |
… | |
476 | later, again, and again, until stopped manually. |
547 | later, again, and again, until stopped manually. |
477 | |
548 | |
478 | The timer itself will do a best-effort at avoiding drift, that is, if you |
549 | The timer itself will do a best-effort at avoiding drift, that is, if you |
479 | configure a timer to trigger every 10 seconds, then it will trigger at |
550 | configure a timer to trigger every 10 seconds, then it will trigger at |
480 | exactly 10 second intervals. If, however, your program cannot keep up with |
551 | exactly 10 second intervals. If, however, your program cannot keep up with |
481 | the timer (ecause it takes longer than those 10 seconds to do stuff) the |
552 | the timer (because it takes longer than those 10 seconds to do stuff) the |
482 | timer will not fire more than once per event loop iteration. |
553 | timer will not fire more than once per event loop iteration. |
483 | |
554 | |
484 | =item ev_timer_again (loop) |
555 | =item ev_timer_again (loop) |
485 | |
556 | |
486 | This will act as if the timer timed out and restart it again if it is |
557 | This will act as if the timer timed out and restart it again if it is |
… | |
… | |
517 | again). |
588 | again). |
518 | |
589 | |
519 | They can also be used to implement vastly more complex timers, such as |
590 | They can also be used to implement vastly more complex timers, such as |
520 | triggering an event on eahc midnight, local time. |
591 | triggering an event on eahc midnight, local time. |
521 | |
592 | |
|
|
593 | As with timers, the callback is guarenteed to be invoked only when the |
|
|
594 | time (C<at>) has been passed, but if multiple periodic timers become ready |
|
|
595 | during the same loop iteration then order of execution is undefined. |
|
|
596 | |
522 | =over 4 |
597 | =over 4 |
523 | |
598 | |
524 | =item ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb) |
599 | =item ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb) |
525 | |
600 | |
526 | =item ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb) |
601 | =item ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb) |
527 | |
602 | |
528 | Lots of arguments, lets sort it out... There are basically three modes of |
603 | Lots of arguments, lets sort it out... There are basically three modes of |
529 | operation, and we will explain them from simplest to complex: |
604 | operation, and we will explain them from simplest to complex: |
530 | |
|
|
531 | |
605 | |
532 | =over 4 |
606 | =over 4 |
533 | |
607 | |
534 | =item * absolute timer (interval = reschedule_cb = 0) |
608 | =item * absolute timer (interval = reschedule_cb = 0) |
535 | |
609 | |
… | |
… | |
677 | =back |
751 | =back |
678 | |
752 | |
679 | =head2 C<ev_prepare> and C<ev_check> - customise your event loop |
753 | =head2 C<ev_prepare> and C<ev_check> - customise your event loop |
680 | |
754 | |
681 | Prepare and check watchers are usually (but not always) used in tandem: |
755 | Prepare and check watchers are usually (but not always) used in tandem: |
682 | Prepare watchers get invoked before the process blocks and check watchers |
756 | prepare watchers get invoked before the process blocks and check watchers |
683 | afterwards. |
757 | afterwards. |
684 | |
758 | |
685 | Their main purpose is to integrate other event mechanisms into libev. This |
759 | Their main purpose is to integrate other event mechanisms into libev. This |
686 | could be used, for example, to track variable changes, implement your own |
760 | could be used, for example, to track variable changes, implement your own |
687 | watchers, integrate net-snmp or a coroutine library and lots more. |
761 | watchers, integrate net-snmp or a coroutine library and lots more. |
… | |
… | |
690 | to be watched by the other library, registering C<ev_io> watchers for |
764 | to be watched by the other library, registering C<ev_io> watchers for |
691 | them and starting an C<ev_timer> watcher for any timeouts (many libraries |
765 | them and starting an C<ev_timer> watcher for any timeouts (many libraries |
692 | provide just this functionality). Then, in the check watcher you check for |
766 | provide just this functionality). Then, in the check watcher you check for |
693 | any events that occured (by checking the pending status of all watchers |
767 | any events that occured (by checking the pending status of all watchers |
694 | and stopping them) and call back into the library. The I/O and timer |
768 | and stopping them) and call back into the library. The I/O and timer |
695 | callbacks will never actually be called (but must be valid neverthelles, |
769 | callbacks will never actually be called (but must be valid nevertheless, |
696 | because you never know, you know?). |
770 | because you never know, you know?). |
697 | |
771 | |
698 | As another example, the Perl Coro module uses these hooks to integrate |
772 | As another example, the Perl Coro module uses these hooks to integrate |
699 | coroutines into libev programs, by yielding to other active coroutines |
773 | coroutines into libev programs, by yielding to other active coroutines |
700 | during each prepare and only letting the process block if no coroutines |
774 | during each prepare and only letting the process block if no coroutines |
701 | are ready to run (its actually more complicated, it only runs coroutines |
775 | are ready to run (it's actually more complicated: it only runs coroutines |
702 | with priority higher than the event loop and one lower priority once, |
776 | with priority higher than or equal to the event loop and one coroutine |
703 | using idle watchers to keep the event loop from blocking if lower-priority |
777 | of lower priority, but only once, using idle watchers to keep the event |
704 | coroutines exist, thus mapping low-priority coroutines to idle/background |
778 | loop from blocking if lower-priority coroutines are active, thus mapping |
705 | tasks). |
779 | low-priority coroutines to idle/background tasks). |
706 | |
780 | |
707 | =over 4 |
781 | =over 4 |
708 | |
782 | |
709 | =item ev_prepare_init (ev_prepare *, callback) |
783 | =item ev_prepare_init (ev_prepare *, callback) |
710 | |
784 | |
… | |
… | |
725 | =item ev_once (loop, int fd, int events, ev_tstamp timeout, callback) |
799 | =item ev_once (loop, int fd, int events, ev_tstamp timeout, callback) |
726 | |
800 | |
727 | This function combines a simple timer and an I/O watcher, calls your |
801 | This function combines a simple timer and an I/O watcher, calls your |
728 | callback on whichever event happens first and automatically stop both |
802 | callback on whichever event happens first and automatically stop both |
729 | watchers. This is useful if you want to wait for a single event on an fd |
803 | watchers. This is useful if you want to wait for a single event on an fd |
730 | or timeout without havign to allocate/configure/start/stop/free one or |
804 | or timeout without having to allocate/configure/start/stop/free one or |
731 | more watchers yourself. |
805 | more watchers yourself. |
732 | |
806 | |
733 | If C<fd> is less than 0, then no I/O watcher will be started and events |
807 | If C<fd> is less than 0, then no I/O watcher will be started and events |
734 | is being ignored. Otherwise, an C<ev_io> watcher for the given C<fd> and |
808 | is being ignored. Otherwise, an C<ev_io> watcher for the given C<fd> and |
735 | C<events> set will be craeted and started. |
809 | C<events> set will be craeted and started. |
… | |
… | |
738 | started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and |
812 | started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and |
739 | repeat = 0) will be started. While C<0> is a valid timeout, it is of |
813 | repeat = 0) will be started. While C<0> is a valid timeout, it is of |
740 | dubious value. |
814 | dubious value. |
741 | |
815 | |
742 | The callback has the type C<void (*cb)(int revents, void *arg)> and gets |
816 | The callback has the type C<void (*cb)(int revents, void *arg)> and gets |
743 | passed an events set like normal event callbacks (with a combination of |
817 | passed an C<revents> set like normal event callbacks (a combination of |
744 | C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMEOUT>) and the C<arg> |
818 | C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMEOUT>) and the C<arg> |
745 | value passed to C<ev_once>: |
819 | value passed to C<ev_once>: |
746 | |
820 | |
747 | static void stdin_ready (int revents, void *arg) |
821 | static void stdin_ready (int revents, void *arg) |
748 | { |
822 | { |
… | |
… | |
769 | |
843 | |
770 | Feed an event as if the given signal occured (loop must be the default loop!). |
844 | Feed an event as if the given signal occured (loop must be the default loop!). |
771 | |
845 | |
772 | =back |
846 | =back |
773 | |
847 | |
|
|
848 | =head1 LIBEVENT EMULATION |
|
|
849 | |
|
|
850 | Libev offers a compatibility emulation layer for libevent. It cannot |
|
|
851 | emulate the internals of libevent, so here are some usage hints: |
|
|
852 | |
|
|
853 | =over 4 |
|
|
854 | |
|
|
855 | =item * Use it by including <event.h>, as usual. |
|
|
856 | |
|
|
857 | =item * The following members are fully supported: ev_base, ev_callback, |
|
|
858 | ev_arg, ev_fd, ev_res, ev_events. |
|
|
859 | |
|
|
860 | =item * Avoid using ev_flags and the EVLIST_*-macros, while it is |
|
|
861 | maintained by libev, it does not work exactly the same way as in libevent (consider |
|
|
862 | it a private API). |
|
|
863 | |
|
|
864 | =item * Priorities are not currently supported. Initialising priorities |
|
|
865 | will fail and all watchers will have the same priority, even though there |
|
|
866 | is an ev_pri field. |
|
|
867 | |
|
|
868 | =item * Other members are not supported. |
|
|
869 | |
|
|
870 | =item * The libev emulation is I<not> ABI compatible to libevent, you need |
|
|
871 | to use the libev header file and library. |
|
|
872 | |
|
|
873 | =back |
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874 | |
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875 | =head1 C++ SUPPORT |
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876 | |
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877 | TBD. |
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878 | |
774 | =head1 AUTHOR |
879 | =head1 AUTHOR |
775 | |
880 | |
776 | Marc Lehmann <libev@schmorp.de>. |
881 | Marc Lehmann <libev@schmorp.de>. |
777 | |
882 | |