… | |
… | |
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 |
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62 | C<ev_now> function is usually faster and also often returns the timestamp |
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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 | |
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152 | This is your standard select(2) backend. Not I<completely> standard, as |
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153 | libev tries to roll its own fd_set with no limits on the number of fds, |
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154 | but if that fails, expect a fairly low limit on the number of fds when |
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155 | using this backend. It doesn't scale too well (O(highest_fd)), but its usually |
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156 | the fastest backend for a low number of fds. |
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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 | |
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160 | And this is your standard poll(2) backend. It's more complicated than |
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161 | select, but handles sparse fds better and has no artificial limit on the |
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162 | number of fds you can use (except it will slow down considerably with a |
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163 | lot of inactive fds). It scales similarly to select, i.e. O(total_fds). |
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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, |
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168 | but it scales phenomenally better. While poll and select usually scale like |
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169 | O(total_fds) where n is the total number of fds (or the highest fd), epoll scales |
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170 | either O(1) or O(active_fds). |
155 | |
171 | |
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172 | While stopping and starting an I/O watcher in the same iteration will |
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173 | result in some caching, there is still a syscall per such incident |
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174 | (because the fd could point to a different file description now), so its |
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175 | best to avoid that. Also, dup()ed file descriptors might not work very |
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176 | well if you register events for both fds. |
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177 | |
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178 | =item C<EVMETHOD_KQUEUE> (value 8, most BSD clones) |
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179 | |
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180 | Kqueue deserves special mention, as at the time of this writing, it |
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181 | was broken on all BSDs except NetBSD (usually it doesn't work with |
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182 | anything but sockets and pipes, except on Darwin, where of course its |
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183 | completely useless). For this reason its not being "autodetected" unless |
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184 | you explicitly specify the flags (i.e. you don't use EVFLAG_AUTO). |
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185 | |
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186 | It scales in the same way as the epoll backend, but the interface to the |
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187 | kernel is more efficient (which says nothing about its actual speed, of |
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188 | course). While starting and stopping an I/O watcher does not cause an |
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189 | extra syscall as with epoll, it still adds up to four event changes per |
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190 | incident, so its best to avoid that. |
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191 | |
156 | =item C<EVMETHOD_DEVPOLL> (solaris 8 only) |
192 | =item C<EVMETHOD_DEVPOLL> (value 16, Solaris 8) |
157 | |
193 | |
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194 | This is not implemented yet (and might never be). |
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195 | |
158 | =item C<EVMETHOD_PORT> (solaris 10 only) |
196 | =item C<EVMETHOD_PORT> (value 32, Solaris 10) |
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197 | |
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198 | This uses the Solaris 10 port mechanism. As with everything on Solaris, |
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199 | it's really slow, but it still scales very well (O(active_fds)). |
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200 | |
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201 | =item C<EVMETHOD_ALL> |
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202 | |
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203 | Try all backends (even potentially broken ones that wouldn't be tried |
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204 | with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as |
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205 | C<EVMETHOD_ALL & ~EVMETHOD_KQUEUE>. |
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206 | |
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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 |
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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 | |
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290 | Here are the gory details of what ev_loop does: |
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291 | |
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292 | 1. If there are no active watchers (reference count is zero), return. |
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293 | 2. Queue and immediately call all prepare watchers. |
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294 | 3. If we have been forked, recreate the kernel state. |
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295 | 4. Update the kernel state with all outstanding changes. |
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296 | 5. Update the "event loop time". |
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297 | 6. Calculate for how long to block. |
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298 | 7. Block the process, waiting for events. |
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299 | 8. Update the "event loop time" and do time jump handling. |
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300 | 9. Queue all outstanding timers. |
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301 | 10. Queue all outstanding periodics. |
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302 | 11. If no events are pending now, queue all idle watchers. |
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303 | 12. Queue all check watchers. |
|
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304 | 13. Call all queued watchers in reverse order (i.e. check watchers first). |
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305 | 14. If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
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306 | was used, return, otherwise continue with step #1. |
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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) |
… | |
… | |
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 (that is, they share the same |
496 | to the same underlying file/socket etc. description (that is, they share |
431 | underlying "file open"). |
497 | the same underlying "file open"). |
432 | |
498 | |
433 | 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 |
434 | (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 |
435 | EVMETHOD_POLL). |
501 | EVMETHOD_POLL). |
436 | |
502 | |
… | |
… | |
452 | given time, and optionally repeating in regular intervals after that. |
518 | given time, and optionally repeating in regular intervals after that. |
453 | |
519 | |
454 | 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 |
455 | times out after an hour and you reset your system clock to last years |
521 | times out after an hour and you reset your system clock to last years |
456 | 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 |
457 | detecting time jumps is hard, and soem inaccuracies are unavoidable (the |
523 | detecting time jumps is hard, and some inaccuracies are unavoidable (the |
458 | monotonic clock option helps a lot here). |
524 | monotonic clock option helps a lot here). |
459 | |
525 | |
460 | The relative timeouts are calculated relative to the C<ev_now ()> |
526 | The relative timeouts are calculated relative to the C<ev_now ()> |
461 | 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 |
462 | of the event triggering whatever timeout you are modifying/starting. If |
528 | of the event triggering whatever timeout you are modifying/starting. If |
463 | 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 |
464 | on the current time, use something like this to adjust for this: |
530 | on the current time, use something like this to adjust for this: |
465 | |
531 | |
466 | 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. |
467 | |
537 | |
468 | =over 4 |
538 | =over 4 |
469 | |
539 | |
470 | =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) |
471 | |
541 | |
… | |
… | |
518 | again). |
588 | again). |
519 | |
589 | |
520 | 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 |
521 | triggering an event on eahc midnight, local time. |
591 | triggering an event on eahc midnight, local time. |
522 | |
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 | |
523 | =over 4 |
597 | =over 4 |
524 | |
598 | |
525 | =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) |
526 | |
600 | |
527 | =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) |
528 | |
602 | |
529 | 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 |
530 | operation, and we will explain them from simplest to complex: |
604 | operation, and we will explain them from simplest to complex: |
531 | |
|
|
532 | |
605 | |
533 | =over 4 |
606 | =over 4 |
534 | |
607 | |
535 | =item * absolute timer (interval = reschedule_cb = 0) |
608 | =item * absolute timer (interval = reschedule_cb = 0) |
536 | |
609 | |
… | |
… | |
772 | |
845 | |
773 | =back |
846 | =back |
774 | |
847 | |
775 | =head1 LIBEVENT EMULATION |
848 | =head1 LIBEVENT EMULATION |
776 | |
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 |
|
|
874 | |
|
|
875 | =head1 C++ SUPPORT |
|
|
876 | |
777 | TBD. |
877 | TBD. |
778 | |
878 | |
779 | =head1 C++ SUPPORT |
|
|
780 | |
|
|
781 | TBD. |
|
|
782 | |
|
|
783 | =head1 AUTHOR |
879 | =head1 AUTHOR |
784 | |
880 | |
785 | Marc Lehmann <libev@schmorp.de>. |
881 | Marc Lehmann <libev@schmorp.de>. |
786 | |
882 | |