… | |
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39 | F<README.embed> in the libev distribution. If libev was configured without |
39 | F<README.embed> in the libev distribution. If libev was configured without |
40 | support for multiple event loops, then all functions taking an initial |
40 | support for multiple event loops, then all functions taking an initial |
41 | argument of name C<loop> (which is always of type C<struct ev_loop *>) |
41 | argument of name C<loop> (which is always of type C<struct ev_loop *>) |
42 | will not have this argument. |
42 | will not have this argument. |
43 | |
43 | |
44 | =head1 TIME AND OTHER GLOBAL FUNCTIONS |
44 | =head1 TIME REPRESENTATION |
45 | |
45 | |
46 | Libev represents time as a single floating point number, representing the |
46 | Libev represents time as a single floating point number, representing the |
47 | (fractional) number of seconds since the (POSIX) epoch (somewhere near |
47 | (fractional) number of seconds since the (POSIX) epoch (somewhere near |
48 | the beginning of 1970, details are complicated, don't ask). This type is |
48 | the beginning of 1970, details are complicated, don't ask). This type is |
49 | called C<ev_tstamp>, which is what you should use too. It usually aliases |
49 | called C<ev_tstamp>, which is what you should use too. It usually aliases |
50 | to the double type in C. |
50 | to the double type in C. |
51 | |
51 | |
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52 | =head1 GLOBAL FUNCTIONS |
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53 | |
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54 | These functions can be called anytime, even before initialising the |
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55 | library in any way. |
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56 | |
52 | =over 4 |
57 | =over 4 |
53 | |
58 | |
54 | =item ev_tstamp ev_time () |
59 | =item ev_tstamp ev_time () |
55 | |
60 | |
56 | 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. |
57 | |
64 | |
58 | =item int ev_version_major () |
65 | =item int ev_version_major () |
59 | |
66 | |
60 | =item int ev_version_minor () |
67 | =item int ev_version_minor () |
61 | |
68 | |
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99 | An event loop is described by a C<struct ev_loop *>. The library knows two |
106 | An event loop is described by a C<struct ev_loop *>. The library knows two |
100 | types of such loops, the I<default> loop, which supports signals and child |
107 | types of such loops, the I<default> loop, which supports signals and child |
101 | events, and dynamically created loops which do not. |
108 | events, and dynamically created loops which do not. |
102 | |
109 | |
103 | If you use threads, a common model is to run the default event loop |
110 | If you use threads, a common model is to run the default event loop |
104 | in your main thread (or in a separate thrad) and for each thread you |
111 | in your main thread (or in a separate thread) and for each thread you |
105 | create, you also create another event loop. Libev itself does no locking |
112 | create, you also create another event loop. Libev itself does no locking |
106 | whatsoever, so if you mix calls to the same event loop in different |
113 | whatsoever, so if you mix calls to the same event loop in different |
107 | threads, make sure you lock (this is usually a bad idea, though, even if |
114 | threads, make sure you lock (this is usually a bad idea, though, even if |
108 | done correctly, because it's hideous and inefficient). |
115 | done correctly, because it's hideous and inefficient). |
109 | |
116 | |
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138 | C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will |
145 | C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will |
139 | 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 |
140 | 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 |
141 | around bugs. |
148 | around bugs. |
142 | |
149 | |
143 | =item C<EVMETHOD_SELECT> (portable select backend) |
150 | =item C<EVMETHOD_SELECT> (value 1, portable select backend) |
144 | |
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 | |
145 | =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) |
146 | |
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 | |
147 | =item C<EVMETHOD_EPOLL> (linux only) |
165 | =item C<EVMETHOD_EPOLL> (value 4, Linux) |
148 | |
166 | |
149 | =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). |
150 | |
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 | |
151 | =item C<EVMETHOD_DEVPOLL> (solaris 8 only) |
192 | =item C<EVMETHOD_DEVPOLL> (value 16, Solaris 8) |
152 | |
193 | |
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194 | This is not implemented yet (and might never be). |
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195 | |
153 | =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 |
154 | |
208 | |
155 | 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 |
156 | 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 |
157 | specified, any backend will do. |
211 | specified, most compiled-in backend will be tried, usually in reverse |
158 | |
212 | order of their flag values :) |
159 | =back |
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160 | |
213 | |
161 | =item struct ev_loop *ev_loop_new (unsigned int flags) |
214 | =item struct ev_loop *ev_loop_new (unsigned int flags) |
162 | |
215 | |
163 | 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 |
164 | 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 |
… | |
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232 | |
285 | |
233 | This flags value could be used to implement alternative looping |
286 | This flags value could be used to implement alternative looping |
234 | 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 |
235 | more generic mechanism. |
288 | more generic mechanism. |
236 | |
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 | |
237 | =item ev_unloop (loop, how) |
308 | =item ev_unloop (loop, how) |
238 | |
309 | |
239 | 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 |
240 | 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 |
241 | 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 |
242 | 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. |
243 | |
314 | |
244 | =item ev_ref (loop) |
315 | =item ev_ref (loop) |
245 | |
316 | |
246 | =item ev_unref (loop) |
317 | =item ev_unref (loop) |
… | |
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299 | |
370 | |
300 | As long as your watcher is active (has been started but not stopped) you |
371 | As long as your watcher is active (has been started but not stopped) you |
301 | must not touch the values stored in it. Most specifically you must never |
372 | must not touch the values stored in it. Most specifically you must never |
302 | reinitialise it or call its set method. |
373 | reinitialise it or call its set method. |
303 | |
374 | |
304 | You cna check whether an event is active by calling the C<ev_is_active |
375 | You can check whether an event is active by calling the C<ev_is_active |
305 | (watcher *)> macro. To see whether an event is outstanding (but the |
376 | (watcher *)> macro. To see whether an event is outstanding (but the |
306 | callback for it has not been called yet) you cna use the C<ev_is_pending |
377 | callback for it has not been called yet) you can use the C<ev_is_pending |
307 | (watcher *)> macro. |
378 | (watcher *)> macro. |
308 | |
379 | |
309 | Each and every callback receives the event loop pointer as first, the |
380 | Each and every callback receives the event loop pointer as first, the |
310 | registered watcher structure as second, and a bitset of received events as |
381 | registered watcher structure as second, and a bitset of received events as |
311 | third argument. |
382 | third argument. |
312 | |
383 | |
313 | The rceeived events usually include a single bit per event type received |
384 | The received events usually include a single bit per event type received |
314 | (you can receive multiple events at the same time). The possible bit masks |
385 | (you can receive multiple events at the same time). The possible bit masks |
315 | are: |
386 | are: |
316 | |
387 | |
317 | =over 4 |
388 | =over 4 |
318 | |
389 | |
… | |
… | |
372 | =back |
443 | =back |
373 | |
444 | |
374 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
445 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
375 | |
446 | |
376 | Each watcher has, by default, a member C<void *data> that you can change |
447 | Each watcher has, by default, a member C<void *data> that you can change |
377 | and read at any time, libev will completely ignore it. This cna be used |
448 | and read at any time, libev will completely ignore it. This can be used |
378 | to associate arbitrary data with your watcher. If you need more data and |
449 | to associate arbitrary data with your watcher. If you need more data and |
379 | don't want to allocate memory and store a pointer to it in that data |
450 | don't want to allocate memory and store a pointer to it in that data |
380 | member, you can also "subclass" the watcher type and provide your own |
451 | member, you can also "subclass" the watcher type and provide your own |
381 | data: |
452 | data: |
382 | |
453 | |
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409 | =head2 C<ev_io> - is this file descriptor readable or writable |
480 | =head2 C<ev_io> - is this file descriptor readable or writable |
410 | |
481 | |
411 | I/O watchers check whether a file descriptor is readable or writable |
482 | I/O watchers check whether a file descriptor is readable or writable |
412 | in each iteration of the event loop (This behaviour is called |
483 | in each iteration of the event loop (This behaviour is called |
413 | level-triggering because you keep receiving events as long as the |
484 | level-triggering because you keep receiving events as long as the |
414 | condition persists. Remember you cna stop the watcher if you don't want to |
485 | condition persists. Remember you can stop the watcher if you don't want to |
415 | act on the event and neither want to receive future events). |
486 | act on the event and neither want to receive future events). |
416 | |
487 | |
417 | 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 |
418 | 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 |
419 | 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 |
420 | required if you know what you are doing). |
491 | required if you know what you are doing). |
421 | |
492 | |
422 | 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 |
423 | (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 |
424 | 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 |
425 | to the same file/socket etc. description. |
496 | to the same underlying file/socket etc. description (that is, they share |
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497 | the same underlying "file open"). |
426 | |
498 | |
427 | 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 |
428 | (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 |
429 | EVMETHOD_POLL). |
501 | EVMETHOD_POLL). |
430 | |
502 | |
… | |
… | |
444 | |
516 | |
445 | 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 |
446 | given time, and optionally repeating in regular intervals after that. |
518 | given time, and optionally repeating in regular intervals after that. |
447 | |
519 | |
448 | 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 |
449 | 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 |
450 | 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 |
451 | detecting time jumps is hard, and soem inaccuracies are unavoidable (the |
523 | detecting time jumps is hard, and some inaccuracies are unavoidable (the |
452 | monotonic clock option helps a lot here). |
524 | monotonic clock option helps a lot here). |
453 | |
525 | |
454 | The relative timeouts are calculated relative to the C<ev_now ()> |
526 | The relative timeouts are calculated relative to the C<ev_now ()> |
455 | 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 |
456 | of the event triggering whatever timeout you are modifying/starting. If |
528 | of the event triggering whatever timeout you are modifying/starting. If |
457 | 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 |
458 | 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: |
459 | |
531 | |
460 | ev_timer_set (&timer, after + ev_now () - ev_time (), 0.); |
532 | ev_timer_set (&timer, after + ev_now () - ev_time (), 0.); |
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533 | |
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534 | The callback is guarenteed to be invoked only when its timeout has passed, |
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535 | but if multiple timers become ready during the same loop iteration then |
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536 | order of execution is undefined. |
461 | |
537 | |
462 | =over 4 |
538 | =over 4 |
463 | |
539 | |
464 | =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) |
465 | |
541 | |
… | |
… | |
471 | later, again, and again, until stopped manually. |
547 | later, again, and again, until stopped manually. |
472 | |
548 | |
473 | 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 |
474 | 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 |
475 | 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 |
476 | 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 |
477 | timer will not fire more than once per event loop iteration. |
553 | timer will not fire more than once per event loop iteration. |
478 | |
554 | |
479 | =item ev_timer_again (loop) |
555 | =item ev_timer_again (loop) |
480 | |
556 | |
481 | 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 |
… | |
… | |
495 | state where you do not expect data to travel on the socket, you can stop |
571 | state where you do not expect data to travel on the socket, you can stop |
496 | the timer, and again will automatically restart it if need be. |
572 | the timer, and again will automatically restart it if need be. |
497 | |
573 | |
498 | =back |
574 | =back |
499 | |
575 | |
500 | =head2 C<ev_periodic> - to cron or not to cron it |
576 | =head2 C<ev_periodic> - to cron or not to cron |
501 | |
577 | |
502 | Periodic watchers are also timers of a kind, but they are very versatile |
578 | Periodic watchers are also timers of a kind, but they are very versatile |
503 | (and unfortunately a bit complex). |
579 | (and unfortunately a bit complex). |
504 | |
580 | |
505 | Unlike C<ev_timer>'s, they are not based on real time (or relative time) |
581 | Unlike C<ev_timer>'s, they are not based on real time (or relative time) |
… | |
… | |
512 | again). |
588 | again). |
513 | |
589 | |
514 | 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 |
515 | triggering an event on eahc midnight, local time. |
591 | triggering an event on eahc midnight, local time. |
516 | |
592 | |
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593 | As with timers, the callback is guarenteed to be invoked only when the |
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594 | time (C<at>) has been passed, but if multiple periodic timers become ready |
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595 | during the same loop iteration then order of execution is undefined. |
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596 | |
517 | =over 4 |
597 | =over 4 |
518 | |
598 | |
519 | =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) |
520 | |
600 | |
521 | =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) |
522 | |
602 | |
523 | 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 |
524 | operation, and we will explain them from simplest to complex: |
604 | operation, and we will explain them from simplest to complex: |
525 | |
|
|
526 | |
605 | |
527 | =over 4 |
606 | =over 4 |
528 | |
607 | |
529 | =item * absolute timer (interval = reschedule_cb = 0) |
608 | =item * absolute timer (interval = reschedule_cb = 0) |
530 | |
609 | |
… | |
… | |
558 | In this mode the values for C<interval> and C<at> are both being |
637 | In this mode the values for C<interval> and C<at> are both being |
559 | ignored. Instead, each time the periodic watcher gets scheduled, the |
638 | ignored. Instead, each time the periodic watcher gets scheduled, the |
560 | reschedule callback will be called with the watcher as first, and the |
639 | reschedule callback will be called with the watcher as first, and the |
561 | current time as second argument. |
640 | current time as second argument. |
562 | |
641 | |
563 | NOTE: I<This callback MUST NOT stop or destroy the periodic or any other |
642 | NOTE: I<This callback MUST NOT stop or destroy any periodic watcher, |
564 | periodic watcher, ever, or make any event loop modifications>. If you need |
643 | ever, or make any event loop modifications>. If you need to stop it, |
565 | to stop it, return C<now + 1e30> (or so, fudge fudge) and stop it afterwards. |
644 | return C<now + 1e30> (or so, fudge fudge) and stop it afterwards (e.g. by |
566 | |
645 | starting a prepare watcher). |
567 | Also, I<< this callback must always return a time that is later than the |
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568 | passed C<now> value >>. Not even C<now> itself will be ok. |
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|
569 | |
646 | |
570 | Its prototype is C<ev_tstamp (*reschedule_cb)(struct ev_periodic *w, |
647 | Its prototype is C<ev_tstamp (*reschedule_cb)(struct ev_periodic *w, |
571 | ev_tstamp now)>, e.g.: |
648 | ev_tstamp now)>, e.g.: |
572 | |
649 | |
573 | static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now) |
650 | static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now) |
… | |
… | |
578 | It must return the next time to trigger, based on the passed time value |
655 | It must return the next time to trigger, based on the passed time value |
579 | (that is, the lowest time value larger than to the second argument). It |
656 | (that is, the lowest time value larger than to the second argument). It |
580 | will usually be called just before the callback will be triggered, but |
657 | will usually be called just before the callback will be triggered, but |
581 | might be called at other times, too. |
658 | might be called at other times, too. |
582 | |
659 | |
|
|
660 | NOTE: I<< This callback must always return a time that is later than the |
|
|
661 | passed C<now> value >>. Not even C<now> itself will do, it I<must> be larger. |
|
|
662 | |
583 | This can be used to create very complex timers, such as a timer that |
663 | This can be used to create very complex timers, such as a timer that |
584 | triggers on each midnight, local time. To do this, you would calculate the |
664 | triggers on each midnight, local time. To do this, you would calculate the |
585 | next midnight after C<now> and return the timestamp value for this. How you do this |
665 | next midnight after C<now> and return the timestamp value for this. How |
586 | is, again, up to you (but it is not trivial). |
666 | you do this is, again, up to you (but it is not trivial, which is the main |
|
|
667 | reason I omitted it as an example). |
587 | |
668 | |
588 | =back |
669 | =back |
589 | |
670 | |
590 | =item ev_periodic_again (loop, ev_periodic *) |
671 | =item ev_periodic_again (loop, ev_periodic *) |
591 | |
672 | |
… | |
… | |
601 | Signal watchers will trigger an event when the process receives a specific |
682 | Signal watchers will trigger an event when the process receives a specific |
602 | signal one or more times. Even though signals are very asynchronous, libev |
683 | signal one or more times. Even though signals are very asynchronous, libev |
603 | will try it's best to deliver signals synchronously, i.e. as part of the |
684 | will try it's best to deliver signals synchronously, i.e. as part of the |
604 | normal event processing, like any other event. |
685 | normal event processing, like any other event. |
605 | |
686 | |
606 | You cna configure as many watchers as you like per signal. Only when the |
687 | You can configure as many watchers as you like per signal. Only when the |
607 | first watcher gets started will libev actually register a signal watcher |
688 | first watcher gets started will libev actually register a signal watcher |
608 | with the kernel (thus it coexists with your own signal handlers as long |
689 | with the kernel (thus it coexists with your own signal handlers as long |
609 | as you don't register any with libev). Similarly, when the last signal |
690 | as you don't register any with libev). Similarly, when the last signal |
610 | watcher for a signal is stopped libev will reset the signal handler to |
691 | watcher for a signal is stopped libev will reset the signal handler to |
611 | SIG_DFL (regardless of what it was set to before). |
692 | SIG_DFL (regardless of what it was set to before). |
… | |
… | |
633 | =item ev_child_set (ev_child *, int pid) |
714 | =item ev_child_set (ev_child *, int pid) |
634 | |
715 | |
635 | Configures the watcher to wait for status changes of process C<pid> (or |
716 | Configures the watcher to wait for status changes of process C<pid> (or |
636 | I<any> process if C<pid> is specified as C<0>). The callback can look |
717 | I<any> process if C<pid> is specified as C<0>). The callback can look |
637 | at the C<rstatus> member of the C<ev_child> watcher structure to see |
718 | at the C<rstatus> member of the C<ev_child> watcher structure to see |
638 | the status word (use the macros from C<sys/wait.h>). The C<rpid> member |
719 | the status word (use the macros from C<sys/wait.h> and see your systems |
639 | contains the pid of the process causing the status change. |
720 | C<waitpid> documentation). The C<rpid> member contains the pid of the |
|
|
721 | process causing the status change. |
640 | |
722 | |
641 | =back |
723 | =back |
642 | |
724 | |
643 | =head2 C<ev_idle> - when you've got nothing better to do |
725 | =head2 C<ev_idle> - when you've got nothing better to do |
644 | |
726 | |
645 | Idle watchers trigger events when there are no other I/O or timer (or |
727 | Idle watchers trigger events when there are no other events are pending |
646 | periodic) events pending. That is, as long as your process is busy |
728 | (prepare, check and other idle watchers do not count). That is, as long |
647 | handling sockets or timeouts it will not be called. But when your process |
729 | as your process is busy handling sockets or timeouts (or even signals, |
648 | is idle all idle watchers are being called again and again - until |
730 | imagine) it will not be triggered. But when your process is idle all idle |
|
|
731 | watchers are being called again and again, once per event loop iteration - |
649 | stopped, that is, or your process receives more events. |
732 | until stopped, that is, or your process receives more events and becomes |
|
|
733 | busy. |
650 | |
734 | |
651 | The most noteworthy effect is that as long as any idle watchers are |
735 | The most noteworthy effect is that as long as any idle watchers are |
652 | active, the process will not block when waiting for new events. |
736 | active, the process will not block when waiting for new events. |
653 | |
737 | |
654 | Apart from keeping your process non-blocking (which is a useful |
738 | Apart from keeping your process non-blocking (which is a useful |
… | |
… | |
664 | kind. There is a C<ev_idle_set> macro, but using it is utterly pointless, |
748 | kind. There is a C<ev_idle_set> macro, but using it is utterly pointless, |
665 | believe me. |
749 | believe me. |
666 | |
750 | |
667 | =back |
751 | =back |
668 | |
752 | |
669 | =head2 prepare and check - your hooks into the event loop |
753 | =head2 C<ev_prepare> and C<ev_check> - customise your event loop |
670 | |
754 | |
671 | Prepare and check watchers usually (but not always) are used in |
755 | Prepare and check watchers are usually (but not always) used in tandem: |
672 | tandom. Prepare watchers get invoked before the process blocks and check |
756 | prepare watchers get invoked before the process blocks and check watchers |
673 | watchers afterwards. |
757 | afterwards. |
674 | |
758 | |
675 | 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 |
676 | 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 |
677 | watchers, integrate net-snmp or a coroutine library and lots more. |
761 | watchers, integrate net-snmp or a coroutine library and lots more. |
678 | |
762 | |
679 | This is done by examining in each prepare call which file descriptors need |
763 | This is done by examining in each prepare call which file descriptors need |
680 | to be watched by the other library, registering C<ev_io> watchers for them |
764 | to be watched by the other library, registering C<ev_io> watchers for |
681 | and starting an C<ev_timer> watcher for any timeouts (many libraries provide |
765 | them and starting an C<ev_timer> watcher for any timeouts (many libraries |
682 | just this functionality). Then, in the check watcher you check for any |
766 | provide just this functionality). Then, in the check watcher you check for |
683 | events that occured (by making your callbacks set soem flags for example) |
767 | any events that occured (by checking the pending status of all watchers |
684 | and call back into the library. |
768 | and stopping them) and call back into the library. The I/O and timer |
|
|
769 | callbacks will never actually be called (but must be valid nevertheless, |
|
|
770 | because you never know, you know?). |
685 | |
771 | |
686 | 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 |
687 | coroutines into libev programs, by yielding to other active coroutines |
773 | coroutines into libev programs, by yielding to other active coroutines |
688 | 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 |
689 | are ready to run. |
775 | are ready to run (it's actually more complicated: it only runs coroutines |
|
|
776 | with priority higher than or equal to the event loop and one coroutine |
|
|
777 | of lower priority, but only once, using idle watchers to keep the event |
|
|
778 | loop from blocking if lower-priority coroutines are active, thus mapping |
|
|
779 | low-priority coroutines to idle/background tasks). |
690 | |
780 | |
691 | =over 4 |
781 | =over 4 |
692 | |
782 | |
693 | =item ev_prepare_init (ev_prepare *, callback) |
783 | =item ev_prepare_init (ev_prepare *, callback) |
694 | |
784 | |
695 | =item ev_check_init (ev_check *, callback) |
785 | =item ev_check_init (ev_check *, callback) |
696 | |
786 | |
697 | Initialises and configures the prepare or check watcher - they have no |
787 | Initialises and configures the prepare or check watcher - they have no |
698 | parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set> |
788 | parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set> |
699 | macros, but using them is utterly, utterly pointless. |
789 | macros, but using them is utterly, utterly and completely pointless. |
700 | |
790 | |
701 | =back |
791 | =back |
702 | |
792 | |
703 | =head1 OTHER FUNCTIONS |
793 | =head1 OTHER FUNCTIONS |
704 | |
794 | |
705 | There are some other fucntions of possible interest. Described. Here. Now. |
795 | There are some other functions of possible interest. Described. Here. Now. |
706 | |
796 | |
707 | =over 4 |
797 | =over 4 |
708 | |
798 | |
709 | =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) |
710 | |
800 | |
711 | 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 |
712 | callback on whichever event happens first and automatically stop both |
802 | callback on whichever event happens first and automatically stop both |
713 | 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 |
714 | 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 |
715 | more watchers yourself. |
805 | more watchers yourself. |
716 | |
806 | |
717 | If C<fd> is less than 0, then no I/O watcher will be started and events is |
807 | If C<fd> is less than 0, then no I/O watcher will be started and events |
718 | ignored. Otherwise, an C<ev_io> watcher for the given C<fd> and C<events> set |
808 | is being ignored. Otherwise, an C<ev_io> watcher for the given C<fd> and |
719 | will be craeted and started. |
809 | C<events> set will be craeted and started. |
720 | |
810 | |
721 | If C<timeout> is less than 0, then no timeout watcher will be |
811 | If C<timeout> is less than 0, then no timeout watcher will be |
722 | started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and repeat |
812 | started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and |
723 | = 0) will be started. |
813 | repeat = 0) will be started. While C<0> is a valid timeout, it is of |
|
|
814 | dubious value. |
724 | |
815 | |
725 | The callback has the type C<void (*cb)(int revents, void *arg)> and |
816 | The callback has the type C<void (*cb)(int revents, void *arg)> and gets |
726 | gets passed an events set (normally a combination of C<EV_ERROR>, C<EV_READ>, |
817 | passed an C<revents> set like normal event callbacks (a combination of |
727 | C<EV_WRITE> or C<EV_TIMEOUT>) and the C<arg> value passed to C<ev_once>: |
818 | C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMEOUT>) and the C<arg> |
|
|
819 | value passed to C<ev_once>: |
728 | |
820 | |
729 | static void stdin_ready (int revents, void *arg) |
821 | static void stdin_ready (int revents, void *arg) |
730 | { |
822 | { |
731 | if (revents & EV_TIMEOUT) |
823 | if (revents & EV_TIMEOUT) |
732 | /* doh, nothing entered */ |
824 | /* doh, nothing entered */; |
733 | else if (revents & EV_READ) |
825 | else if (revents & EV_READ) |
734 | /* stdin might have data for us, joy! */ |
826 | /* stdin might have data for us, joy! */; |
735 | } |
827 | } |
736 | |
828 | |
737 | ev_once (STDIN_FILENO, EV_READm 10., stdin_ready, 0); |
829 | ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
738 | |
830 | |
739 | =item ev_feed_event (loop, watcher, int events) |
831 | =item ev_feed_event (loop, watcher, int events) |
740 | |
832 | |
741 | Feeds the given event set into the event loop, as if the specified event |
833 | Feeds the given event set into the event loop, as if the specified event |
742 | has happened for the specified watcher (which must be a pointer to an |
834 | had happened for the specified watcher (which must be a pointer to an |
743 | initialised but not necessarily active event watcher). |
835 | initialised but not necessarily started event watcher). |
744 | |
836 | |
745 | =item ev_feed_fd_event (loop, int fd, int revents) |
837 | =item ev_feed_fd_event (loop, int fd, int revents) |
746 | |
838 | |
747 | Feed an event on the given fd, as if a file descriptor backend detected it. |
839 | Feed an event on the given fd, as if a file descriptor backend detected |
|
|
840 | the given events it. |
748 | |
841 | |
749 | =item ev_feed_signal_event (loop, int signum) |
842 | =item ev_feed_signal_event (loop, int signum) |
750 | |
843 | |
751 | 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!). |
752 | |
845 | |
753 | =back |
846 | =back |
754 | |
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 |
|
|
874 | |
|
|
875 | =head1 C++ SUPPORT |
|
|
876 | |
|
|
877 | TBD. |
|
|
878 | |
755 | =head1 AUTHOR |
879 | =head1 AUTHOR |
756 | |
880 | |
757 | Marc Lehmann <libev@schmorp.de>. |
881 | Marc Lehmann <libev@schmorp.de>. |
758 | |
882 | |