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1 | =encoding utf-8 |
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2 | |
1 | =head1 NAME |
3 | =head1 NAME |
2 | |
4 | |
3 | libev - a high performance full-featured event loop written in C |
5 | libev - a high performance full-featured event loop written in C |
4 | |
6 | |
5 | =head1 SYNOPSIS |
7 | =head1 SYNOPSIS |
… | |
… | |
82 | |
84 | |
83 | =head1 WHAT TO READ WHEN IN A HURRY |
85 | =head1 WHAT TO READ WHEN IN A HURRY |
84 | |
86 | |
85 | This manual tries to be very detailed, but unfortunately, this also makes |
87 | This manual tries to be very detailed, but unfortunately, this also makes |
86 | it very long. If you just want to know the basics of libev, I suggest |
88 | it very long. If you just want to know the basics of libev, I suggest |
87 | reading L<ANATOMY OF A WATCHER>, then the L<EXAMPLE PROGRAM> above and |
89 | reading L</ANATOMY OF A WATCHER>, then the L</EXAMPLE PROGRAM> above and |
88 | look up the missing functions in L<GLOBAL FUNCTIONS> and the C<ev_io> and |
90 | look up the missing functions in L</GLOBAL FUNCTIONS> and the C<ev_io> and |
89 | C<ev_timer> sections in L<WATCHER TYPES>. |
91 | C<ev_timer> sections in L</WATCHER TYPES>. |
90 | |
92 | |
91 | =head1 ABOUT LIBEV |
93 | =head1 ABOUT LIBEV |
92 | |
94 | |
93 | Libev is an event loop: you register interest in certain events (such as a |
95 | Libev is an event loop: you register interest in certain events (such as a |
94 | file descriptor being readable or a timeout occurring), and it will manage |
96 | file descriptor being readable or a timeout occurring), and it will manage |
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… | |
263 | |
265 | |
264 | You could override this function in high-availability programs to, say, |
266 | You could override this function in high-availability programs to, say, |
265 | free some memory if it cannot allocate memory, to use a special allocator, |
267 | free some memory if it cannot allocate memory, to use a special allocator, |
266 | or even to sleep a while and retry until some memory is available. |
268 | or even to sleep a while and retry until some memory is available. |
267 | |
269 | |
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270 | Example: The following is the C<realloc> function that libev itself uses |
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271 | which should work with C<realloc> and C<free> functions of all kinds and |
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272 | is probably a good basis for your own implementation. |
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273 | |
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274 | static void * |
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275 | ev_realloc_emul (void *ptr, long size) EV_NOEXCEPT |
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276 | { |
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277 | if (size) |
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278 | return realloc (ptr, size); |
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279 | |
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280 | free (ptr); |
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281 | return 0; |
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282 | } |
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283 | |
268 | Example: Replace the libev allocator with one that waits a bit and then |
284 | Example: Replace the libev allocator with one that waits a bit and then |
269 | retries (example requires a standards-compliant C<realloc>). |
285 | retries. |
270 | |
286 | |
271 | static void * |
287 | static void * |
272 | persistent_realloc (void *ptr, size_t size) |
288 | persistent_realloc (void *ptr, size_t size) |
273 | { |
289 | { |
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290 | if (!size) |
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291 | { |
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292 | free (ptr); |
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293 | return 0; |
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294 | } |
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295 | |
274 | for (;;) |
296 | for (;;) |
275 | { |
297 | { |
276 | void *newptr = realloc (ptr, size); |
298 | void *newptr = realloc (ptr, size); |
277 | |
299 | |
278 | if (newptr) |
300 | if (newptr) |
… | |
… | |
396 | |
418 | |
397 | If this flag bit is or'ed into the flag value (or the program runs setuid |
419 | If this flag bit is or'ed into the flag value (or the program runs setuid |
398 | or setgid) then libev will I<not> look at the environment variable |
420 | or setgid) then libev will I<not> look at the environment variable |
399 | C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will |
421 | C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will |
400 | override the flags completely if it is found in the environment. This is |
422 | override the flags completely if it is found in the environment. This is |
401 | useful to try out specific backends to test their performance, or to work |
423 | useful to try out specific backends to test their performance, to work |
402 | around bugs. |
424 | around bugs, or to make libev threadsafe (accessing environment variables |
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425 | cannot be done in a threadsafe way, but usually it works if no other |
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426 | thread modifies them). |
403 | |
427 | |
404 | =item C<EVFLAG_FORKCHECK> |
428 | =item C<EVFLAG_FORKCHECK> |
405 | |
429 | |
406 | Instead of calling C<ev_loop_fork> manually after a fork, you can also |
430 | Instead of calling C<ev_loop_fork> manually after a fork, you can also |
407 | make libev check for a fork in each iteration by enabling this flag. |
431 | make libev check for a fork in each iteration by enabling this flag. |
408 | |
432 | |
409 | This works by calling C<getpid ()> on every iteration of the loop, |
433 | This works by calling C<getpid ()> on every iteration of the loop, |
410 | and thus this might slow down your event loop if you do a lot of loop |
434 | and thus this might slow down your event loop if you do a lot of loop |
411 | iterations and little real work, but is usually not noticeable (on my |
435 | iterations and little real work, but is usually not noticeable (on my |
412 | GNU/Linux system for example, C<getpid> is actually a simple 5-insn sequence |
436 | GNU/Linux system for example, C<getpid> is actually a simple 5-insn |
413 | without a system call and thus I<very> fast, but my GNU/Linux system also has |
437 | sequence without a system call and thus I<very> fast, but my GNU/Linux |
414 | C<pthread_atfork> which is even faster). |
438 | system also has C<pthread_atfork> which is even faster). (Update: glibc |
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439 | versions 2.25 apparently removed the C<getpid> optimisation again). |
415 | |
440 | |
416 | The big advantage of this flag is that you can forget about fork (and |
441 | The big advantage of this flag is that you can forget about fork (and |
417 | forget about forgetting to tell libev about forking) when you use this |
442 | forget about forgetting to tell libev about forking, although you still |
418 | flag. |
443 | have to ignore C<SIGPIPE>) when you use this flag. |
419 | |
444 | |
420 | This flag setting cannot be overridden or specified in the C<LIBEV_FLAGS> |
445 | This flag setting cannot be overridden or specified in the C<LIBEV_FLAGS> |
421 | environment variable. |
446 | environment variable. |
422 | |
447 | |
423 | =item C<EVFLAG_NOINOTIFY> |
448 | =item C<EVFLAG_NOINOTIFY> |
… | |
… | |
569 | kernel is more efficient (which says nothing about its actual speed, of |
594 | kernel is more efficient (which says nothing about its actual speed, of |
570 | course). While stopping, setting and starting an I/O watcher does never |
595 | course). While stopping, setting and starting an I/O watcher does never |
571 | cause an extra system call as with C<EVBACKEND_EPOLL>, it still adds up to |
596 | cause an extra system call as with C<EVBACKEND_EPOLL>, it still adds up to |
572 | two event changes per incident. Support for C<fork ()> is very bad (you |
597 | two event changes per incident. Support for C<fork ()> is very bad (you |
573 | might have to leak fd's on fork, but it's more sane than epoll) and it |
598 | might have to leak fd's on fork, but it's more sane than epoll) and it |
574 | drops fds silently in similarly hard-to-detect cases |
599 | drops fds silently in similarly hard-to-detect cases. |
575 | |
600 | |
576 | This backend usually performs well under most conditions. |
601 | This backend usually performs well under most conditions. |
577 | |
602 | |
578 | While nominally embeddable in other event loops, this doesn't work |
603 | While nominally embeddable in other event loops, this doesn't work |
579 | everywhere, so you might need to test for this. And since it is broken |
604 | everywhere, so you might need to test for this. And since it is broken |
… | |
… | |
678 | If you need dynamically allocated loops it is better to use C<ev_loop_new> |
703 | If you need dynamically allocated loops it is better to use C<ev_loop_new> |
679 | and C<ev_loop_destroy>. |
704 | and C<ev_loop_destroy>. |
680 | |
705 | |
681 | =item ev_loop_fork (loop) |
706 | =item ev_loop_fork (loop) |
682 | |
707 | |
683 | This function sets a flag that causes subsequent C<ev_run> iterations to |
708 | This function sets a flag that causes subsequent C<ev_run> iterations |
684 | reinitialise the kernel state for backends that have one. Despite the |
709 | to reinitialise the kernel state for backends that have one. Despite |
685 | name, you can call it anytime, but it makes most sense after forking, in |
710 | the name, you can call it anytime you are allowed to start or stop |
686 | the child process. You I<must> call it (or use C<EVFLAG_FORKCHECK>) in the |
711 | watchers (except inside an C<ev_prepare> callback), but it makes most |
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712 | sense after forking, in the child process. You I<must> call it (or use |
687 | child before resuming or calling C<ev_run>. |
713 | C<EVFLAG_FORKCHECK>) in the child before resuming or calling C<ev_run>. |
688 | |
714 | |
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715 | In addition, if you want to reuse a loop (via this function or |
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716 | C<EVFLAG_FORKCHECK>), you I<also> have to ignore C<SIGPIPE>. |
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717 | |
689 | Again, you I<have> to call it on I<any> loop that you want to re-use after |
718 | Again, you I<have> to call it on I<any> loop that you want to re-use after |
690 | a fork, I<even if you do not plan to use the loop in the parent>. This is |
719 | a fork, I<even if you do not plan to use the loop in the parent>. This is |
691 | because some kernel interfaces *cough* I<kqueue> *cough* do funny things |
720 | because some kernel interfaces *cough* I<kqueue> *cough* do funny things |
692 | during fork. |
721 | during fork. |
693 | |
722 | |
694 | On the other hand, you only need to call this function in the child |
723 | On the other hand, you only need to call this function in the child |
… | |
… | |
764 | |
793 | |
765 | This function is rarely useful, but when some event callback runs for a |
794 | This function is rarely useful, but when some event callback runs for a |
766 | very long time without entering the event loop, updating libev's idea of |
795 | very long time without entering the event loop, updating libev's idea of |
767 | the current time is a good idea. |
796 | the current time is a good idea. |
768 | |
797 | |
769 | See also L<The special problem of time updates> in the C<ev_timer> section. |
798 | See also L</The special problem of time updates> in the C<ev_timer> section. |
770 | |
799 | |
771 | =item ev_suspend (loop) |
800 | =item ev_suspend (loop) |
772 | |
801 | |
773 | =item ev_resume (loop) |
802 | =item ev_resume (loop) |
774 | |
803 | |
… | |
… | |
1318 | |
1347 | |
1319 | =item callback ev_cb (ev_TYPE *watcher) |
1348 | =item callback ev_cb (ev_TYPE *watcher) |
1320 | |
1349 | |
1321 | Returns the callback currently set on the watcher. |
1350 | Returns the callback currently set on the watcher. |
1322 | |
1351 | |
1323 | =item ev_cb_set (ev_TYPE *watcher, callback) |
1352 | =item ev_set_cb (ev_TYPE *watcher, callback) |
1324 | |
1353 | |
1325 | Change the callback. You can change the callback at virtually any time |
1354 | Change the callback. You can change the callback at virtually any time |
1326 | (modulo threads). |
1355 | (modulo threads). |
1327 | |
1356 | |
1328 | =item ev_set_priority (ev_TYPE *watcher, int priority) |
1357 | =item ev_set_priority (ev_TYPE *watcher, int priority) |
… | |
… | |
1346 | or might not have been clamped to the valid range. |
1375 | or might not have been clamped to the valid range. |
1347 | |
1376 | |
1348 | The default priority used by watchers when no priority has been set is |
1377 | The default priority used by watchers when no priority has been set is |
1349 | always C<0>, which is supposed to not be too high and not be too low :). |
1378 | always C<0>, which is supposed to not be too high and not be too low :). |
1350 | |
1379 | |
1351 | See L<WATCHER PRIORITY MODELS>, below, for a more thorough treatment of |
1380 | See L</WATCHER PRIORITY MODELS>, below, for a more thorough treatment of |
1352 | priorities. |
1381 | priorities. |
1353 | |
1382 | |
1354 | =item ev_invoke (loop, ev_TYPE *watcher, int revents) |
1383 | =item ev_invoke (loop, ev_TYPE *watcher, int revents) |
1355 | |
1384 | |
1356 | Invoke the C<watcher> with the given C<loop> and C<revents>. Neither |
1385 | Invoke the C<watcher> with the given C<loop> and C<revents>. Neither |
… | |
… | |
1381 | See also C<ev_feed_fd_event> and C<ev_feed_signal_event> for related |
1410 | See also C<ev_feed_fd_event> and C<ev_feed_signal_event> for related |
1382 | functions that do not need a watcher. |
1411 | functions that do not need a watcher. |
1383 | |
1412 | |
1384 | =back |
1413 | =back |
1385 | |
1414 | |
1386 | See also the L<ASSOCIATING CUSTOM DATA WITH A WATCHER> and L<BUILDING YOUR |
1415 | See also the L</ASSOCIATING CUSTOM DATA WITH A WATCHER> and L</BUILDING YOUR |
1387 | OWN COMPOSITE WATCHERS> idioms. |
1416 | OWN COMPOSITE WATCHERS> idioms. |
1388 | |
1417 | |
1389 | =head2 WATCHER STATES |
1418 | =head2 WATCHER STATES |
1390 | |
1419 | |
1391 | There are various watcher states mentioned throughout this manual - |
1420 | There are various watcher states mentioned throughout this manual - |
… | |
… | |
1393 | transition between them will be described in more detail - and while these |
1422 | transition between them will be described in more detail - and while these |
1394 | rules might look complicated, they usually do "the right thing". |
1423 | rules might look complicated, they usually do "the right thing". |
1395 | |
1424 | |
1396 | =over 4 |
1425 | =over 4 |
1397 | |
1426 | |
1398 | =item initialiased |
1427 | =item initialised |
1399 | |
1428 | |
1400 | Before a watcher can be registered with the event loop it has to be |
1429 | Before a watcher can be registered with the event loop it has to be |
1401 | initialised. This can be done with a call to C<ev_TYPE_init>, or calls to |
1430 | initialised. This can be done with a call to C<ev_TYPE_init>, or calls to |
1402 | C<ev_init> followed by the watcher-specific C<ev_TYPE_set> function. |
1431 | C<ev_init> followed by the watcher-specific C<ev_TYPE_set> function. |
1403 | |
1432 | |
… | |
… | |
2024 | |
2053 | |
2025 | The relative timeouts are calculated relative to the C<ev_now ()> |
2054 | The relative timeouts are calculated relative to the C<ev_now ()> |
2026 | time. This is usually the right thing as this timestamp refers to the time |
2055 | time. This is usually the right thing as this timestamp refers to the time |
2027 | of the event triggering whatever timeout you are modifying/starting. If |
2056 | of the event triggering whatever timeout you are modifying/starting. If |
2028 | you suspect event processing to be delayed and you I<need> to base the |
2057 | you suspect event processing to be delayed and you I<need> to base the |
2029 | timeout on the current time, use something like this to adjust for this: |
2058 | timeout on the current time, use something like the following to adjust |
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2059 | for it: |
2030 | |
2060 | |
2031 | ev_timer_set (&timer, after + ev_now () - ev_time (), 0.); |
2061 | ev_timer_set (&timer, after + (ev_time () - ev_now ()), 0.); |
2032 | |
2062 | |
2033 | If the event loop is suspended for a long time, you can also force an |
2063 | If the event loop is suspended for a long time, you can also force an |
2034 | update of the time returned by C<ev_now ()> by calling C<ev_now_update |
2064 | update of the time returned by C<ev_now ()> by calling C<ev_now_update |
2035 | ()>. |
2065 | ()>, although that will push the event time of all outstanding events |
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2066 | further into the future. |
2036 | |
2067 | |
2037 | =head3 The special problem of unsynchronised clocks |
2068 | =head3 The special problem of unsynchronised clocks |
2038 | |
2069 | |
2039 | Modern systems have a variety of clocks - libev itself uses the normal |
2070 | Modern systems have a variety of clocks - libev itself uses the normal |
2040 | "wall clock" clock and, if available, the monotonic clock (to avoid time |
2071 | "wall clock" clock and, if available, the monotonic clock (to avoid time |
… | |
… | |
2103 | |
2134 | |
2104 | =item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat) |
2135 | =item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat) |
2105 | |
2136 | |
2106 | =item ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat) |
2137 | =item ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat) |
2107 | |
2138 | |
2108 | Configure the timer to trigger after C<after> seconds. If C<repeat> |
2139 | Configure the timer to trigger after C<after> seconds (fractional and |
2109 | is C<0.>, then it will automatically be stopped once the timeout is |
2140 | negative values are supported). If C<repeat> is C<0.>, then it will |
2110 | reached. If it is positive, then the timer will automatically be |
2141 | automatically be stopped once the timeout is reached. If it is positive, |
2111 | configured to trigger again C<repeat> seconds later, again, and again, |
2142 | then the timer will automatically be configured to trigger again C<repeat> |
2112 | until stopped manually. |
2143 | seconds later, again, and again, until stopped manually. |
2113 | |
2144 | |
2114 | The timer itself will do a best-effort at avoiding drift, that is, if |
2145 | The timer itself will do a best-effort at avoiding drift, that is, if |
2115 | you configure a timer to trigger every 10 seconds, then it will normally |
2146 | you configure a timer to trigger every 10 seconds, then it will normally |
2116 | trigger at exactly 10 second intervals. If, however, your program cannot |
2147 | trigger at exactly 10 second intervals. If, however, your program cannot |
2117 | keep up with the timer (because it takes longer than those 10 seconds to |
2148 | keep up with the timer (because it takes longer than those 10 seconds to |
… | |
… | |
2136 | =item If the timer is repeating, make the C<repeat> value the new timeout |
2167 | =item If the timer is repeating, make the C<repeat> value the new timeout |
2137 | and start the timer, if necessary. |
2168 | and start the timer, if necessary. |
2138 | |
2169 | |
2139 | =back |
2170 | =back |
2140 | |
2171 | |
2141 | This sounds a bit complicated, see L<Be smart about timeouts>, above, for a |
2172 | This sounds a bit complicated, see L</Be smart about timeouts>, above, for a |
2142 | usage example. |
2173 | usage example. |
2143 | |
2174 | |
2144 | =item ev_tstamp ev_timer_remaining (loop, ev_timer *) |
2175 | =item ev_tstamp ev_timer_remaining (loop, ev_timer *) |
2145 | |
2176 | |
2146 | Returns the remaining time until a timer fires. If the timer is active, |
2177 | Returns the remaining time until a timer fires. If the timer is active, |
… | |
… | |
2199 | Periodic watchers are also timers of a kind, but they are very versatile |
2230 | Periodic watchers are also timers of a kind, but they are very versatile |
2200 | (and unfortunately a bit complex). |
2231 | (and unfortunately a bit complex). |
2201 | |
2232 | |
2202 | Unlike C<ev_timer>, periodic watchers are not based on real time (or |
2233 | Unlike C<ev_timer>, periodic watchers are not based on real time (or |
2203 | relative time, the physical time that passes) but on wall clock time |
2234 | relative time, the physical time that passes) but on wall clock time |
2204 | (absolute time, the thing you can read on your calender or clock). The |
2235 | (absolute time, the thing you can read on your calendar or clock). The |
2205 | difference is that wall clock time can run faster or slower than real |
2236 | difference is that wall clock time can run faster or slower than real |
2206 | time, and time jumps are not uncommon (e.g. when you adjust your |
2237 | time, and time jumps are not uncommon (e.g. when you adjust your |
2207 | wrist-watch). |
2238 | wrist-watch). |
2208 | |
2239 | |
2209 | You can tell a periodic watcher to trigger after some specific point |
2240 | You can tell a periodic watcher to trigger after some specific point |
… | |
… | |
2214 | C<ev_timer>, which would still trigger roughly 10 seconds after starting |
2245 | C<ev_timer>, which would still trigger roughly 10 seconds after starting |
2215 | it, as it uses a relative timeout). |
2246 | it, as it uses a relative timeout). |
2216 | |
2247 | |
2217 | C<ev_periodic> watchers can also be used to implement vastly more complex |
2248 | C<ev_periodic> watchers can also be used to implement vastly more complex |
2218 | timers, such as triggering an event on each "midnight, local time", or |
2249 | timers, such as triggering an event on each "midnight, local time", or |
2219 | other complicated rules. This cannot be done with C<ev_timer> watchers, as |
2250 | other complicated rules. This cannot easily be done with C<ev_timer> |
2220 | those cannot react to time jumps. |
2251 | watchers, as those cannot react to time jumps. |
2221 | |
2252 | |
2222 | As with timers, the callback is guaranteed to be invoked only when the |
2253 | As with timers, the callback is guaranteed to be invoked only when the |
2223 | point in time where it is supposed to trigger has passed. If multiple |
2254 | point in time where it is supposed to trigger has passed. If multiple |
2224 | timers become ready during the same loop iteration then the ones with |
2255 | timers become ready during the same loop iteration then the ones with |
2225 | earlier time-out values are invoked before ones with later time-out values |
2256 | earlier time-out values are invoked before ones with later time-out values |
… | |
… | |
2311 | |
2342 | |
2312 | NOTE: I<< This callback must always return a time that is higher than or |
2343 | NOTE: I<< This callback must always return a time that is higher than or |
2313 | equal to the passed C<now> value >>. |
2344 | equal to the passed C<now> value >>. |
2314 | |
2345 | |
2315 | This can be used to create very complex timers, such as a timer that |
2346 | This can be used to create very complex timers, such as a timer that |
2316 | triggers on "next midnight, local time". To do this, you would calculate the |
2347 | triggers on "next midnight, local time". To do this, you would calculate |
2317 | next midnight after C<now> and return the timestamp value for this. How |
2348 | the next midnight after C<now> and return the timestamp value for |
2318 | you do this is, again, up to you (but it is not trivial, which is the main |
2349 | this. Here is a (completely untested, no error checking) example on how to |
2319 | reason I omitted it as an example). |
2350 | do this: |
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2351 | |
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2352 | #include <time.h> |
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2353 | |
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2354 | static ev_tstamp |
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2355 | my_rescheduler (ev_periodic *w, ev_tstamp now) |
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2356 | { |
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|
2357 | time_t tnow = (time_t)now; |
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2358 | struct tm tm; |
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|
2359 | localtime_r (&tnow, &tm); |
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|
2360 | |
|
|
2361 | tm.tm_sec = tm.tm_min = tm.tm_hour = 0; // midnight current day |
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|
2362 | ++tm.tm_mday; // midnight next day |
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|
2363 | |
|
|
2364 | return mktime (&tm); |
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|
2365 | } |
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|
2366 | |
|
|
2367 | Note: this code might run into trouble on days that have more then two |
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|
2368 | midnights (beginning and end). |
2320 | |
2369 | |
2321 | =back |
2370 | =back |
2322 | |
2371 | |
2323 | =item ev_periodic_again (loop, ev_periodic *) |
2372 | =item ev_periodic_again (loop, ev_periodic *) |
2324 | |
2373 | |
… | |
… | |
2389 | |
2438 | |
2390 | ev_periodic hourly_tick; |
2439 | ev_periodic hourly_tick; |
2391 | ev_periodic_init (&hourly_tick, clock_cb, |
2440 | ev_periodic_init (&hourly_tick, clock_cb, |
2392 | fmod (ev_now (loop), 3600.), 3600., 0); |
2441 | fmod (ev_now (loop), 3600.), 3600., 0); |
2393 | ev_periodic_start (loop, &hourly_tick); |
2442 | ev_periodic_start (loop, &hourly_tick); |
2394 | |
2443 | |
2395 | |
2444 | |
2396 | =head2 C<ev_signal> - signal me when a signal gets signalled! |
2445 | =head2 C<ev_signal> - signal me when a signal gets signalled! |
2397 | |
2446 | |
2398 | Signal watchers will trigger an event when the process receives a specific |
2447 | Signal watchers will trigger an event when the process receives a specific |
2399 | signal one or more times. Even though signals are very asynchronous, libev |
2448 | signal one or more times. Even though signals are very asynchronous, libev |
… | |
… | |
2409 | only within the same loop, i.e. you can watch for C<SIGINT> in your |
2458 | only within the same loop, i.e. you can watch for C<SIGINT> in your |
2410 | default loop and for C<SIGIO> in another loop, but you cannot watch for |
2459 | default loop and for C<SIGIO> in another loop, but you cannot watch for |
2411 | C<SIGINT> in both the default loop and another loop at the same time. At |
2460 | C<SIGINT> in both the default loop and another loop at the same time. At |
2412 | the moment, C<SIGCHLD> is permanently tied to the default loop. |
2461 | the moment, C<SIGCHLD> is permanently tied to the default loop. |
2413 | |
2462 | |
2414 | When the first watcher gets started will libev actually register something |
2463 | Only after the first watcher for a signal is started will libev actually |
2415 | with the kernel (thus it coexists with your own signal handlers as long as |
2464 | register something with the kernel. It thus coexists with your own signal |
2416 | you don't register any with libev for the same signal). |
2465 | handlers as long as you don't register any with libev for the same signal. |
2417 | |
2466 | |
2418 | If possible and supported, libev will install its handlers with |
2467 | If possible and supported, libev will install its handlers with |
2419 | C<SA_RESTART> (or equivalent) behaviour enabled, so system calls should |
2468 | C<SA_RESTART> (or equivalent) behaviour enabled, so system calls should |
2420 | not be unduly interrupted. If you have a problem with system calls getting |
2469 | not be unduly interrupted. If you have a problem with system calls getting |
2421 | interrupted by signals you can block all signals in an C<ev_check> watcher |
2470 | interrupted by signals you can block all signals in an C<ev_check> watcher |
… | |
… | |
2606 | |
2655 | |
2607 | =head2 C<ev_stat> - did the file attributes just change? |
2656 | =head2 C<ev_stat> - did the file attributes just change? |
2608 | |
2657 | |
2609 | This watches a file system path for attribute changes. That is, it calls |
2658 | This watches a file system path for attribute changes. That is, it calls |
2610 | C<stat> on that path in regular intervals (or when the OS says it changed) |
2659 | C<stat> on that path in regular intervals (or when the OS says it changed) |
2611 | and sees if it changed compared to the last time, invoking the callback if |
2660 | and sees if it changed compared to the last time, invoking the callback |
2612 | it did. |
2661 | if it did. Starting the watcher C<stat>'s the file, so only changes that |
|
|
2662 | happen after the watcher has been started will be reported. |
2613 | |
2663 | |
2614 | The path does not need to exist: changing from "path exists" to "path does |
2664 | The path does not need to exist: changing from "path exists" to "path does |
2615 | not exist" is a status change like any other. The condition "path does not |
2665 | not exist" is a status change like any other. The condition "path does not |
2616 | exist" (or more correctly "path cannot be stat'ed") is signified by the |
2666 | exist" (or more correctly "path cannot be stat'ed") is signified by the |
2617 | C<st_nlink> field being zero (which is otherwise always forced to be at |
2667 | C<st_nlink> field being zero (which is otherwise always forced to be at |
… | |
… | |
2847 | Apart from keeping your process non-blocking (which is a useful |
2897 | Apart from keeping your process non-blocking (which is a useful |
2848 | effect on its own sometimes), idle watchers are a good place to do |
2898 | effect on its own sometimes), idle watchers are a good place to do |
2849 | "pseudo-background processing", or delay processing stuff to after the |
2899 | "pseudo-background processing", or delay processing stuff to after the |
2850 | event loop has handled all outstanding events. |
2900 | event loop has handled all outstanding events. |
2851 | |
2901 | |
|
|
2902 | =head3 Abusing an C<ev_idle> watcher for its side-effect |
|
|
2903 | |
|
|
2904 | As long as there is at least one active idle watcher, libev will never |
|
|
2905 | sleep unnecessarily. Or in other words, it will loop as fast as possible. |
|
|
2906 | For this to work, the idle watcher doesn't need to be invoked at all - the |
|
|
2907 | lowest priority will do. |
|
|
2908 | |
|
|
2909 | This mode of operation can be useful together with an C<ev_check> watcher, |
|
|
2910 | to do something on each event loop iteration - for example to balance load |
|
|
2911 | between different connections. |
|
|
2912 | |
|
|
2913 | See L</Abusing an ev_check watcher for its side-effect> for a longer |
|
|
2914 | example. |
|
|
2915 | |
2852 | =head3 Watcher-Specific Functions and Data Members |
2916 | =head3 Watcher-Specific Functions and Data Members |
2853 | |
2917 | |
2854 | =over 4 |
2918 | =over 4 |
2855 | |
2919 | |
2856 | =item ev_idle_init (ev_idle *, callback) |
2920 | =item ev_idle_init (ev_idle *, callback) |
… | |
… | |
2867 | callback, free it. Also, use no error checking, as usual. |
2931 | callback, free it. Also, use no error checking, as usual. |
2868 | |
2932 | |
2869 | static void |
2933 | static void |
2870 | idle_cb (struct ev_loop *loop, ev_idle *w, int revents) |
2934 | idle_cb (struct ev_loop *loop, ev_idle *w, int revents) |
2871 | { |
2935 | { |
|
|
2936 | // stop the watcher |
|
|
2937 | ev_idle_stop (loop, w); |
|
|
2938 | |
|
|
2939 | // now we can free it |
2872 | free (w); |
2940 | free (w); |
|
|
2941 | |
2873 | // now do something you wanted to do when the program has |
2942 | // now do something you wanted to do when the program has |
2874 | // no longer anything immediate to do. |
2943 | // no longer anything immediate to do. |
2875 | } |
2944 | } |
2876 | |
2945 | |
2877 | ev_idle *idle_watcher = malloc (sizeof (ev_idle)); |
2946 | ev_idle *idle_watcher = malloc (sizeof (ev_idle)); |
… | |
… | |
2879 | ev_idle_start (loop, idle_watcher); |
2948 | ev_idle_start (loop, idle_watcher); |
2880 | |
2949 | |
2881 | |
2950 | |
2882 | =head2 C<ev_prepare> and C<ev_check> - customise your event loop! |
2951 | =head2 C<ev_prepare> and C<ev_check> - customise your event loop! |
2883 | |
2952 | |
2884 | Prepare and check watchers are usually (but not always) used in pairs: |
2953 | Prepare and check watchers are often (but not always) used in pairs: |
2885 | prepare watchers get invoked before the process blocks and check watchers |
2954 | prepare watchers get invoked before the process blocks and check watchers |
2886 | afterwards. |
2955 | afterwards. |
2887 | |
2956 | |
2888 | You I<must not> call C<ev_run> or similar functions that enter |
2957 | You I<must not> call C<ev_run> (or similar functions that enter the |
2889 | the current event loop from either C<ev_prepare> or C<ev_check> |
2958 | current event loop) or C<ev_loop_fork> from either C<ev_prepare> or |
2890 | watchers. Other loops than the current one are fine, however. The |
2959 | C<ev_check> watchers. Other loops than the current one are fine, |
2891 | rationale behind this is that you do not need to check for recursion in |
2960 | however. The rationale behind this is that you do not need to check |
2892 | those watchers, i.e. the sequence will always be C<ev_prepare>, blocking, |
2961 | for recursion in those watchers, i.e. the sequence will always be |
2893 | C<ev_check> so if you have one watcher of each kind they will always be |
2962 | C<ev_prepare>, blocking, C<ev_check> so if you have one watcher of each |
2894 | called in pairs bracketing the blocking call. |
2963 | kind they will always be called in pairs bracketing the blocking call. |
2895 | |
2964 | |
2896 | Their main purpose is to integrate other event mechanisms into libev and |
2965 | Their main purpose is to integrate other event mechanisms into libev and |
2897 | their use is somewhat advanced. They could be used, for example, to track |
2966 | their use is somewhat advanced. They could be used, for example, to track |
2898 | variable changes, implement your own watchers, integrate net-snmp or a |
2967 | variable changes, implement your own watchers, integrate net-snmp or a |
2899 | coroutine library and lots more. They are also occasionally useful if |
2968 | coroutine library and lots more. They are also occasionally useful if |
… | |
… | |
2917 | with priority higher than or equal to the event loop and one coroutine |
2986 | with priority higher than or equal to the event loop and one coroutine |
2918 | of lower priority, but only once, using idle watchers to keep the event |
2987 | of lower priority, but only once, using idle watchers to keep the event |
2919 | loop from blocking if lower-priority coroutines are active, thus mapping |
2988 | loop from blocking if lower-priority coroutines are active, thus mapping |
2920 | low-priority coroutines to idle/background tasks). |
2989 | low-priority coroutines to idle/background tasks). |
2921 | |
2990 | |
2922 | It is recommended to give C<ev_check> watchers highest (C<EV_MAXPRI>) |
2991 | When used for this purpose, it is recommended to give C<ev_check> watchers |
2923 | priority, to ensure that they are being run before any other watchers |
2992 | highest (C<EV_MAXPRI>) priority, to ensure that they are being run before |
2924 | after the poll (this doesn't matter for C<ev_prepare> watchers). |
2993 | any other watchers after the poll (this doesn't matter for C<ev_prepare> |
|
|
2994 | watchers). |
2925 | |
2995 | |
2926 | Also, C<ev_check> watchers (and C<ev_prepare> watchers, too) should not |
2996 | Also, C<ev_check> watchers (and C<ev_prepare> watchers, too) should not |
2927 | activate ("feed") events into libev. While libev fully supports this, they |
2997 | activate ("feed") events into libev. While libev fully supports this, they |
2928 | might get executed before other C<ev_check> watchers did their job. As |
2998 | might get executed before other C<ev_check> watchers did their job. As |
2929 | C<ev_check> watchers are often used to embed other (non-libev) event |
2999 | C<ev_check> watchers are often used to embed other (non-libev) event |
2930 | loops those other event loops might be in an unusable state until their |
3000 | loops those other event loops might be in an unusable state until their |
2931 | C<ev_check> watcher ran (always remind yourself to coexist peacefully with |
3001 | C<ev_check> watcher ran (always remind yourself to coexist peacefully with |
2932 | others). |
3002 | others). |
|
|
3003 | |
|
|
3004 | =head3 Abusing an C<ev_check> watcher for its side-effect |
|
|
3005 | |
|
|
3006 | C<ev_check> (and less often also C<ev_prepare>) watchers can also be |
|
|
3007 | useful because they are called once per event loop iteration. For |
|
|
3008 | example, if you want to handle a large number of connections fairly, you |
|
|
3009 | normally only do a bit of work for each active connection, and if there |
|
|
3010 | is more work to do, you wait for the next event loop iteration, so other |
|
|
3011 | connections have a chance of making progress. |
|
|
3012 | |
|
|
3013 | Using an C<ev_check> watcher is almost enough: it will be called on the |
|
|
3014 | next event loop iteration. However, that isn't as soon as possible - |
|
|
3015 | without external events, your C<ev_check> watcher will not be invoked. |
|
|
3016 | |
|
|
3017 | This is where C<ev_idle> watchers come in handy - all you need is a |
|
|
3018 | single global idle watcher that is active as long as you have one active |
|
|
3019 | C<ev_check> watcher. The C<ev_idle> watcher makes sure the event loop |
|
|
3020 | will not sleep, and the C<ev_check> watcher makes sure a callback gets |
|
|
3021 | invoked. Neither watcher alone can do that. |
2933 | |
3022 | |
2934 | =head3 Watcher-Specific Functions and Data Members |
3023 | =head3 Watcher-Specific Functions and Data Members |
2935 | |
3024 | |
2936 | =over 4 |
3025 | =over 4 |
2937 | |
3026 | |
… | |
… | |
3138 | |
3227 | |
3139 | =over 4 |
3228 | =over 4 |
3140 | |
3229 | |
3141 | =item ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop) |
3230 | =item ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop) |
3142 | |
3231 | |
3143 | =item ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop) |
3232 | =item ev_embed_set (ev_embed *, struct ev_loop *embedded_loop) |
3144 | |
3233 | |
3145 | Configures the watcher to embed the given loop, which must be |
3234 | Configures the watcher to embed the given loop, which must be |
3146 | embeddable. If the callback is C<0>, then C<ev_embed_sweep> will be |
3235 | embeddable. If the callback is C<0>, then C<ev_embed_sweep> will be |
3147 | invoked automatically, otherwise it is the responsibility of the callback |
3236 | invoked automatically, otherwise it is the responsibility of the callback |
3148 | to invoke it (it will continue to be called until the sweep has been done, |
3237 | to invoke it (it will continue to be called until the sweep has been done, |
… | |
… | |
3169 | used). |
3258 | used). |
3170 | |
3259 | |
3171 | struct ev_loop *loop_hi = ev_default_init (0); |
3260 | struct ev_loop *loop_hi = ev_default_init (0); |
3172 | struct ev_loop *loop_lo = 0; |
3261 | struct ev_loop *loop_lo = 0; |
3173 | ev_embed embed; |
3262 | ev_embed embed; |
3174 | |
3263 | |
3175 | // see if there is a chance of getting one that works |
3264 | // see if there is a chance of getting one that works |
3176 | // (remember that a flags value of 0 means autodetection) |
3265 | // (remember that a flags value of 0 means autodetection) |
3177 | loop_lo = ev_embeddable_backends () & ev_recommended_backends () |
3266 | loop_lo = ev_embeddable_backends () & ev_recommended_backends () |
3178 | ? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ()) |
3267 | ? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ()) |
3179 | : 0; |
3268 | : 0; |
… | |
… | |
3193 | C<loop_socket>. (One might optionally use C<EVFLAG_NOENV>, too). |
3282 | C<loop_socket>. (One might optionally use C<EVFLAG_NOENV>, too). |
3194 | |
3283 | |
3195 | struct ev_loop *loop = ev_default_init (0); |
3284 | struct ev_loop *loop = ev_default_init (0); |
3196 | struct ev_loop *loop_socket = 0; |
3285 | struct ev_loop *loop_socket = 0; |
3197 | ev_embed embed; |
3286 | ev_embed embed; |
3198 | |
3287 | |
3199 | if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE) |
3288 | if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE) |
3200 | if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE)) |
3289 | if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE)) |
3201 | { |
3290 | { |
3202 | ev_embed_init (&embed, 0, loop_socket); |
3291 | ev_embed_init (&embed, 0, loop_socket); |
3203 | ev_embed_start (loop, &embed); |
3292 | ev_embed_start (loop, &embed); |
… | |
… | |
3211 | |
3300 | |
3212 | =head2 C<ev_fork> - the audacity to resume the event loop after a fork |
3301 | =head2 C<ev_fork> - the audacity to resume the event loop after a fork |
3213 | |
3302 | |
3214 | Fork watchers are called when a C<fork ()> was detected (usually because |
3303 | Fork watchers are called when a C<fork ()> was detected (usually because |
3215 | whoever is a good citizen cared to tell libev about it by calling |
3304 | whoever is a good citizen cared to tell libev about it by calling |
3216 | C<ev_default_fork> or C<ev_loop_fork>). The invocation is done before the |
3305 | C<ev_loop_fork>). The invocation is done before the event loop blocks next |
3217 | event loop blocks next and before C<ev_check> watchers are being called, |
3306 | and before C<ev_check> watchers are being called, and only in the child |
3218 | and only in the child after the fork. If whoever good citizen calling |
3307 | after the fork. If whoever good citizen calling C<ev_default_fork> cheats |
3219 | C<ev_default_fork> cheats and calls it in the wrong process, the fork |
3308 | and calls it in the wrong process, the fork handlers will be invoked, too, |
3220 | handlers will be invoked, too, of course. |
3309 | of course. |
3221 | |
3310 | |
3222 | =head3 The special problem of life after fork - how is it possible? |
3311 | =head3 The special problem of life after fork - how is it possible? |
3223 | |
3312 | |
3224 | Most uses of C<fork()> consist of forking, then some simple calls to set |
3313 | Most uses of C<fork ()> consist of forking, then some simple calls to set |
3225 | up/change the process environment, followed by a call to C<exec()>. This |
3314 | up/change the process environment, followed by a call to C<exec()>. This |
3226 | sequence should be handled by libev without any problems. |
3315 | sequence should be handled by libev without any problems. |
3227 | |
3316 | |
3228 | This changes when the application actually wants to do event handling |
3317 | This changes when the application actually wants to do event handling |
3229 | in the child, or both parent in child, in effect "continuing" after the |
3318 | in the child, or both parent in child, in effect "continuing" after the |
… | |
… | |
3467 | |
3556 | |
3468 | There are some other functions of possible interest. Described. Here. Now. |
3557 | There are some other functions of possible interest. Described. Here. Now. |
3469 | |
3558 | |
3470 | =over 4 |
3559 | =over 4 |
3471 | |
3560 | |
3472 | =item ev_once (loop, int fd, int events, ev_tstamp timeout, callback) |
3561 | =item ev_once (loop, int fd, int events, ev_tstamp timeout, callback, arg) |
3473 | |
3562 | |
3474 | This function combines a simple timer and an I/O watcher, calls your |
3563 | This function combines a simple timer and an I/O watcher, calls your |
3475 | callback on whichever event happens first and automatically stops both |
3564 | callback on whichever event happens first and automatically stops both |
3476 | watchers. This is useful if you want to wait for a single event on an fd |
3565 | watchers. This is useful if you want to wait for a single event on an fd |
3477 | or timeout without having to allocate/configure/start/stop/free one or |
3566 | or timeout without having to allocate/configure/start/stop/free one or |
… | |
… | |
3619 | already been invoked. |
3708 | already been invoked. |
3620 | |
3709 | |
3621 | A common way around all these issues is to make sure that |
3710 | A common way around all these issues is to make sure that |
3622 | C<start_new_request> I<always> returns before the callback is invoked. If |
3711 | C<start_new_request> I<always> returns before the callback is invoked. If |
3623 | C<start_new_request> immediately knows the result, it can artificially |
3712 | C<start_new_request> immediately knows the result, it can artificially |
3624 | delay invoking the callback by e.g. using a C<prepare> or C<idle> watcher |
3713 | delay invoking the callback by using a C<prepare> or C<idle> watcher for |
3625 | for example, or more sneakily, by reusing an existing (stopped) watcher |
3714 | example, or more sneakily, by reusing an existing (stopped) watcher and |
3626 | and pushing it into the pending queue: |
3715 | pushing it into the pending queue: |
3627 | |
3716 | |
3628 | ev_set_cb (watcher, callback); |
3717 | ev_set_cb (watcher, callback); |
3629 | ev_feed_event (EV_A_ watcher, 0); |
3718 | ev_feed_event (EV_A_ watcher, 0); |
3630 | |
3719 | |
3631 | This way, C<start_new_request> can safely return before the callback is |
3720 | This way, C<start_new_request> can safely return before the callback is |
… | |
… | |
3639 | |
3728 | |
3640 | This brings the problem of exiting - a callback might want to finish the |
3729 | This brings the problem of exiting - a callback might want to finish the |
3641 | main C<ev_run> call, but not the nested one (e.g. user clicked "Quit", but |
3730 | main C<ev_run> call, but not the nested one (e.g. user clicked "Quit", but |
3642 | a modal "Are you sure?" dialog is still waiting), or just the nested one |
3731 | a modal "Are you sure?" dialog is still waiting), or just the nested one |
3643 | and not the main one (e.g. user clocked "Ok" in a modal dialog), or some |
3732 | and not the main one (e.g. user clocked "Ok" in a modal dialog), or some |
3644 | other combination: In these cases, C<ev_break> will not work alone. |
3733 | other combination: In these cases, a simple C<ev_break> will not work. |
3645 | |
3734 | |
3646 | The solution is to maintain "break this loop" variable for each C<ev_run> |
3735 | The solution is to maintain "break this loop" variable for each C<ev_run> |
3647 | invocation, and use a loop around C<ev_run> until the condition is |
3736 | invocation, and use a loop around C<ev_run> until the condition is |
3648 | triggered, using C<EVRUN_ONCE>: |
3737 | triggered, using C<EVRUN_ONCE>: |
3649 | |
3738 | |
… | |
… | |
3835 | called): |
3924 | called): |
3836 | |
3925 | |
3837 | void |
3926 | void |
3838 | wait_for_event (ev_watcher *w) |
3927 | wait_for_event (ev_watcher *w) |
3839 | { |
3928 | { |
3840 | ev_cb_set (w) = current_coro; |
3929 | ev_set_cb (w, current_coro); |
3841 | switch_to (libev_coro); |
3930 | switch_to (libev_coro); |
3842 | } |
3931 | } |
3843 | |
3932 | |
3844 | That basically suspends the coroutine inside C<wait_for_event> and |
3933 | That basically suspends the coroutine inside C<wait_for_event> and |
3845 | continues the libev coroutine, which, when appropriate, switches back to |
3934 | continues the libev coroutine, which, when appropriate, switches back to |
… | |
… | |
3848 | You can do similar tricks if you have, say, threads with an event queue - |
3937 | You can do similar tricks if you have, say, threads with an event queue - |
3849 | instead of storing a coroutine, you store the queue object and instead of |
3938 | instead of storing a coroutine, you store the queue object and instead of |
3850 | switching to a coroutine, you push the watcher onto the queue and notify |
3939 | switching to a coroutine, you push the watcher onto the queue and notify |
3851 | any waiters. |
3940 | any waiters. |
3852 | |
3941 | |
3853 | To embed libev, see L<EMBEDDING>, but in short, it's easiest to create two |
3942 | To embed libev, see L</EMBEDDING>, but in short, it's easiest to create two |
3854 | files, F<my_ev.h> and F<my_ev.c> that include the respective libev files: |
3943 | files, F<my_ev.h> and F<my_ev.c> that include the respective libev files: |
3855 | |
3944 | |
3856 | // my_ev.h |
3945 | // my_ev.h |
3857 | #define EV_CB_DECLARE(type) struct my_coro *cb; |
3946 | #define EV_CB_DECLARE(type) struct my_coro *cb; |
3858 | #define EV_CB_INVOKE(watcher) switch_to ((watcher)->cb); |
3947 | #define EV_CB_INVOKE(watcher) switch_to ((watcher)->cb) |
3859 | #include "../libev/ev.h" |
3948 | #include "../libev/ev.h" |
3860 | |
3949 | |
3861 | // my_ev.c |
3950 | // my_ev.c |
3862 | #define EV_H "my_ev.h" |
3951 | #define EV_H "my_ev.h" |
3863 | #include "../libev/ev.c" |
3952 | #include "../libev/ev.c" |
… | |
… | |
3909 | The normal C API should work fine when used from C++: both ev.h and the |
3998 | The normal C API should work fine when used from C++: both ev.h and the |
3910 | libev sources can be compiled as C++. Therefore, code that uses the C API |
3999 | libev sources can be compiled as C++. Therefore, code that uses the C API |
3911 | will work fine. |
4000 | will work fine. |
3912 | |
4001 | |
3913 | Proper exception specifications might have to be added to callbacks passed |
4002 | Proper exception specifications might have to be added to callbacks passed |
3914 | to libev: exceptions may be thrown only from watcher callbacks, all |
4003 | to libev: exceptions may be thrown only from watcher callbacks, all other |
3915 | other callbacks (allocator, syserr, loop acquire/release and periodioc |
4004 | callbacks (allocator, syserr, loop acquire/release and periodic reschedule |
3916 | reschedule callbacks) must not throw exceptions, and might need a C<throw |
4005 | callbacks) must not throw exceptions, and might need a C<noexcept> |
3917 | ()> specification. If you have code that needs to be compiled as both C |
4006 | specification. If you have code that needs to be compiled as both C and |
3918 | and C++ you can use the C<EV_THROW> macro for this: |
4007 | C++ you can use the C<EV_NOEXCEPT> macro for this: |
3919 | |
4008 | |
3920 | static void |
4009 | static void |
3921 | fatal_error (const char *msg) EV_THROW |
4010 | fatal_error (const char *msg) EV_NOEXCEPT |
3922 | { |
4011 | { |
3923 | perror (msg); |
4012 | perror (msg); |
3924 | abort (); |
4013 | abort (); |
3925 | } |
4014 | } |
3926 | |
4015 | |
… | |
… | |
3940 | Libev comes with some simplistic wrapper classes for C++ that mainly allow |
4029 | Libev comes with some simplistic wrapper classes for C++ that mainly allow |
3941 | you to use some convenience methods to start/stop watchers and also change |
4030 | you to use some convenience methods to start/stop watchers and also change |
3942 | the callback model to a model using method callbacks on objects. |
4031 | the callback model to a model using method callbacks on objects. |
3943 | |
4032 | |
3944 | To use it, |
4033 | To use it, |
3945 | |
4034 | |
3946 | #include <ev++.h> |
4035 | #include <ev++.h> |
3947 | |
4036 | |
3948 | This automatically includes F<ev.h> and puts all of its definitions (many |
4037 | This automatically includes F<ev.h> and puts all of its definitions (many |
3949 | of them macros) into the global namespace. All C++ specific things are |
4038 | of them macros) into the global namespace. All C++ specific things are |
3950 | put into the C<ev> namespace. It should support all the same embedding |
4039 | put into the C<ev> namespace. It should support all the same embedding |
… | |
… | |
4053 | void operator() (ev::io &w, int revents) |
4142 | void operator() (ev::io &w, int revents) |
4054 | { |
4143 | { |
4055 | ... |
4144 | ... |
4056 | } |
4145 | } |
4057 | } |
4146 | } |
4058 | |
4147 | |
4059 | myfunctor f; |
4148 | myfunctor f; |
4060 | |
4149 | |
4061 | ev::io w; |
4150 | ev::io w; |
4062 | w.set (&f); |
4151 | w.set (&f); |
4063 | |
4152 | |
… | |
… | |
4081 | Associates a different C<struct ev_loop> with this watcher. You can only |
4170 | Associates a different C<struct ev_loop> with this watcher. You can only |
4082 | do this when the watcher is inactive (and not pending either). |
4171 | do this when the watcher is inactive (and not pending either). |
4083 | |
4172 | |
4084 | =item w->set ([arguments]) |
4173 | =item w->set ([arguments]) |
4085 | |
4174 | |
4086 | Basically the same as C<ev_TYPE_set>, with the same arguments. Either this |
4175 | Basically the same as C<ev_TYPE_set> (except for C<ev::embed> watchers>), |
4087 | method or a suitable start method must be called at least once. Unlike the |
4176 | with the same arguments. Either this method or a suitable start method |
4088 | C counterpart, an active watcher gets automatically stopped and restarted |
4177 | must be called at least once. Unlike the C counterpart, an active watcher |
4089 | when reconfiguring it with this method. |
4178 | gets automatically stopped and restarted when reconfiguring it with this |
|
|
4179 | method. |
|
|
4180 | |
|
|
4181 | For C<ev::embed> watchers this method is called C<set_embed>, to avoid |
|
|
4182 | clashing with the C<set (loop)> method. |
4090 | |
4183 | |
4091 | =item w->start () |
4184 | =item w->start () |
4092 | |
4185 | |
4093 | Starts the watcher. Note that there is no C<loop> argument, as the |
4186 | Starts the watcher. Note that there is no C<loop> argument, as the |
4094 | constructor already stores the event loop. |
4187 | constructor already stores the event loop. |
… | |
… | |
4198 | |
4291 | |
4199 | Brian Maher has written a partial interface to libev for lua (at the |
4292 | Brian Maher has written a partial interface to libev for lua (at the |
4200 | time of this writing, only C<ev_io> and C<ev_timer>), to be found at |
4293 | time of this writing, only C<ev_io> and C<ev_timer>), to be found at |
4201 | L<http://github.com/brimworks/lua-ev>. |
4294 | L<http://github.com/brimworks/lua-ev>. |
4202 | |
4295 | |
|
|
4296 | =item Javascript |
|
|
4297 | |
|
|
4298 | Node.js (L<http://nodejs.org>) uses libev as the underlying event library. |
|
|
4299 | |
|
|
4300 | =item Others |
|
|
4301 | |
|
|
4302 | There are others, and I stopped counting. |
|
|
4303 | |
4203 | =back |
4304 | =back |
4204 | |
4305 | |
4205 | |
4306 | |
4206 | =head1 MACRO MAGIC |
4307 | =head1 MACRO MAGIC |
4207 | |
4308 | |
… | |
… | |
4324 | ev_vars.h |
4425 | ev_vars.h |
4325 | ev_wrap.h |
4426 | ev_wrap.h |
4326 | |
4427 | |
4327 | ev_win32.c required on win32 platforms only |
4428 | ev_win32.c required on win32 platforms only |
4328 | |
4429 | |
4329 | ev_select.c only when select backend is enabled (which is enabled by default) |
4430 | ev_select.c only when select backend is enabled |
4330 | ev_poll.c only when poll backend is enabled (disabled by default) |
4431 | ev_poll.c only when poll backend is enabled |
4331 | ev_epoll.c only when the epoll backend is enabled (disabled by default) |
4432 | ev_epoll.c only when the epoll backend is enabled |
4332 | ev_kqueue.c only when the kqueue backend is enabled (disabled by default) |
4433 | ev_kqueue.c only when the kqueue backend is enabled |
4333 | ev_port.c only when the solaris port backend is enabled (disabled by default) |
4434 | ev_port.c only when the solaris port backend is enabled |
4334 | |
4435 | |
4335 | F<ev.c> includes the backend files directly when enabled, so you only need |
4436 | F<ev.c> includes the backend files directly when enabled, so you only need |
4336 | to compile this single file. |
4437 | to compile this single file. |
4337 | |
4438 | |
4338 | =head3 LIBEVENT COMPATIBILITY API |
4439 | =head3 LIBEVENT COMPATIBILITY API |
… | |
… | |
4505 | |
4606 | |
4506 | If programs implement their own fd to handle mapping on win32, then this |
4607 | If programs implement their own fd to handle mapping on win32, then this |
4507 | macro can be used to override the C<close> function, useful to unregister |
4608 | macro can be used to override the C<close> function, useful to unregister |
4508 | file descriptors again. Note that the replacement function has to close |
4609 | file descriptors again. Note that the replacement function has to close |
4509 | the underlying OS handle. |
4610 | the underlying OS handle. |
|
|
4611 | |
|
|
4612 | =item EV_USE_WSASOCKET |
|
|
4613 | |
|
|
4614 | If defined to be C<1>, libev will use C<WSASocket> to create its internal |
|
|
4615 | communication socket, which works better in some environments. Otherwise, |
|
|
4616 | the normal C<socket> function will be used, which works better in other |
|
|
4617 | environments. |
4510 | |
4618 | |
4511 | =item EV_USE_POLL |
4619 | =item EV_USE_POLL |
4512 | |
4620 | |
4513 | If defined to be C<1>, libev will compile in support for the C<poll>(2) |
4621 | If defined to be C<1>, libev will compile in support for the C<poll>(2) |
4514 | backend. Otherwise it will be enabled on non-win32 platforms. It |
4622 | backend. Otherwise it will be enabled on non-win32 platforms. It |
… | |
… | |
4559 | different cpus (or different cpu cores). This reduces dependencies |
4667 | different cpus (or different cpu cores). This reduces dependencies |
4560 | and makes libev faster. |
4668 | and makes libev faster. |
4561 | |
4669 | |
4562 | =item EV_NO_THREADS |
4670 | =item EV_NO_THREADS |
4563 | |
4671 | |
4564 | If defined to be C<1>, libev will assume that it will never be called |
4672 | If defined to be C<1>, libev will assume that it will never be called from |
4565 | from different threads, which is a stronger assumption than C<EV_NO_SMP>, |
4673 | different threads (that includes signal handlers), which is a stronger |
4566 | above. This reduces dependencies and makes libev faster. |
4674 | assumption than C<EV_NO_SMP>, above. This reduces dependencies and makes |
|
|
4675 | libev faster. |
4567 | |
4676 | |
4568 | =item EV_ATOMIC_T |
4677 | =item EV_ATOMIC_T |
4569 | |
4678 | |
4570 | Libev requires an integer type (suitable for storing C<0> or C<1>) whose |
4679 | Libev requires an integer type (suitable for storing C<0> or C<1>) whose |
4571 | access is atomic and serialised with respect to other threads or signal |
4680 | access is atomic with respect to other threads or signal contexts. No |
4572 | contexts. No such type is easily found in the C language, so you can |
4681 | such type is easily found in the C language, so you can provide your own |
4573 | provide your own type that you know is safe for your purposes. It is used |
4682 | type that you know is safe for your purposes. It is used both for signal |
4574 | both for signal handler "locking" as well as for signal and thread safety |
4683 | handler "locking" as well as for signal and thread safety in C<ev_async> |
4575 | in C<ev_async> watchers. |
4684 | watchers. |
4576 | |
4685 | |
4577 | In the absence of this define, libev will use C<sig_atomic_t volatile> |
4686 | In the absence of this define, libev will use C<sig_atomic_t volatile> |
4578 | (from F<signal.h>), which is usually good enough on most platforms, |
4687 | (from F<signal.h>), which is usually good enough on most platforms. |
4579 | although strictly speaking using a type that also implies a memory fence |
|
|
4580 | is required. |
|
|
4581 | |
4688 | |
4582 | =item EV_H (h) |
4689 | =item EV_H (h) |
4583 | |
4690 | |
4584 | The name of the F<ev.h> header file used to include it. The default if |
4691 | The name of the F<ev.h> header file used to include it. The default if |
4585 | undefined is C<"ev.h"> in F<event.h>, F<ev.c> and F<ev++.h>. This can be |
4692 | undefined is C<"ev.h"> in F<event.h>, F<ev.c> and F<ev++.h>. This can be |
… | |
… | |
4953 | default loop and triggering an C<ev_async> watcher from the default loop |
5060 | default loop and triggering an C<ev_async> watcher from the default loop |
4954 | watcher callback into the event loop interested in the signal. |
5061 | watcher callback into the event loop interested in the signal. |
4955 | |
5062 | |
4956 | =back |
5063 | =back |
4957 | |
5064 | |
4958 | See also L<THREAD LOCKING EXAMPLE>. |
5065 | See also L</THREAD LOCKING EXAMPLE>. |
4959 | |
5066 | |
4960 | =head3 COROUTINES |
5067 | =head3 COROUTINES |
4961 | |
5068 | |
4962 | Libev is very accommodating to coroutines ("cooperative threads"): |
5069 | Libev is very accommodating to coroutines ("cooperative threads"): |
4963 | libev fully supports nesting calls to its functions from different |
5070 | libev fully supports nesting calls to its functions from different |
… | |
… | |
5232 | structure (guaranteed by POSIX but not by ISO C for example), but it also |
5339 | structure (guaranteed by POSIX but not by ISO C for example), but it also |
5233 | assumes that the same (machine) code can be used to call any watcher |
5340 | assumes that the same (machine) code can be used to call any watcher |
5234 | callback: The watcher callbacks have different type signatures, but libev |
5341 | callback: The watcher callbacks have different type signatures, but libev |
5235 | calls them using an C<ev_watcher *> internally. |
5342 | calls them using an C<ev_watcher *> internally. |
5236 | |
5343 | |
|
|
5344 | =item null pointers and integer zero are represented by 0 bytes |
|
|
5345 | |
|
|
5346 | Libev uses C<memset> to initialise structs and arrays to C<0> bytes, and |
|
|
5347 | relies on this setting pointers and integers to null. |
|
|
5348 | |
5237 | =item pointer accesses must be thread-atomic |
5349 | =item pointer accesses must be thread-atomic |
5238 | |
5350 | |
5239 | Accessing a pointer value must be atomic, it must both be readable and |
5351 | Accessing a pointer value must be atomic, it must both be readable and |
5240 | writable in one piece - this is the case on all current architectures. |
5352 | writable in one piece - this is the case on all current architectures. |
5241 | |
5353 | |
… | |
… | |
5254 | thread" or will block signals process-wide, both behaviours would |
5366 | thread" or will block signals process-wide, both behaviours would |
5255 | be compatible with libev. Interaction between C<sigprocmask> and |
5367 | be compatible with libev. Interaction between C<sigprocmask> and |
5256 | C<pthread_sigmask> could complicate things, however. |
5368 | C<pthread_sigmask> could complicate things, however. |
5257 | |
5369 | |
5258 | The most portable way to handle signals is to block signals in all threads |
5370 | The most portable way to handle signals is to block signals in all threads |
5259 | except the initial one, and run the default loop in the initial thread as |
5371 | except the initial one, and run the signal handling loop in the initial |
5260 | well. |
5372 | thread as well. |
5261 | |
5373 | |
5262 | =item C<long> must be large enough for common memory allocation sizes |
5374 | =item C<long> must be large enough for common memory allocation sizes |
5263 | |
5375 | |
5264 | To improve portability and simplify its API, libev uses C<long> internally |
5376 | To improve portability and simplify its API, libev uses C<long> internally |
5265 | instead of C<size_t> when allocating its data structures. On non-POSIX |
5377 | instead of C<size_t> when allocating its data structures. On non-POSIX |
… | |
… | |
5369 | =over 4 |
5481 | =over 4 |
5370 | |
5482 | |
5371 | =item C<EV_COMPAT3> backwards compatibility mechanism |
5483 | =item C<EV_COMPAT3> backwards compatibility mechanism |
5372 | |
5484 | |
5373 | The backward compatibility mechanism can be controlled by |
5485 | The backward compatibility mechanism can be controlled by |
5374 | C<EV_COMPAT3>. See L<PREPROCESSOR SYMBOLS/MACROS> in the L<EMBEDDING> |
5486 | C<EV_COMPAT3>. See L</"PREPROCESSOR SYMBOLS/MACROS"> in the L</EMBEDDING> |
5375 | section. |
5487 | section. |
5376 | |
5488 | |
5377 | =item C<ev_default_destroy> and C<ev_default_fork> have been removed |
5489 | =item C<ev_default_destroy> and C<ev_default_fork> have been removed |
5378 | |
5490 | |
5379 | These calls can be replaced easily by their C<ev_loop_xxx> counterparts: |
5491 | These calls can be replaced easily by their C<ev_loop_xxx> counterparts: |
… | |
… | |
5422 | =over 4 |
5534 | =over 4 |
5423 | |
5535 | |
5424 | =item active |
5536 | =item active |
5425 | |
5537 | |
5426 | A watcher is active as long as it has been started and not yet stopped. |
5538 | A watcher is active as long as it has been started and not yet stopped. |
5427 | See L<WATCHER STATES> for details. |
5539 | See L</WATCHER STATES> for details. |
5428 | |
5540 | |
5429 | =item application |
5541 | =item application |
5430 | |
5542 | |
5431 | In this document, an application is whatever is using libev. |
5543 | In this document, an application is whatever is using libev. |
5432 | |
5544 | |
… | |
… | |
5468 | watchers and events. |
5580 | watchers and events. |
5469 | |
5581 | |
5470 | =item pending |
5582 | =item pending |
5471 | |
5583 | |
5472 | A watcher is pending as soon as the corresponding event has been |
5584 | A watcher is pending as soon as the corresponding event has been |
5473 | detected. See L<WATCHER STATES> for details. |
5585 | detected. See L</WATCHER STATES> for details. |
5474 | |
5586 | |
5475 | =item real time |
5587 | =item real time |
5476 | |
5588 | |
5477 | The physical time that is observed. It is apparently strictly monotonic :) |
5589 | The physical time that is observed. It is apparently strictly monotonic :) |
5478 | |
5590 | |