… | |
… | |
43 | |
43 | |
44 | int |
44 | int |
45 | main (void) |
45 | main (void) |
46 | { |
46 | { |
47 | // use the default event loop unless you have special needs |
47 | // use the default event loop unless you have special needs |
48 | struct ev_loop *loop = ev_default_loop (0); |
48 | struct ev_loop *loop = EV_DEFAULT; |
49 | |
49 | |
50 | // initialise an io watcher, then start it |
50 | // initialise an io watcher, then start it |
51 | // this one will watch for stdin to become readable |
51 | // this one will watch for stdin to become readable |
52 | ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ); |
52 | ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ); |
53 | ev_io_start (loop, &stdin_watcher); |
53 | ev_io_start (loop, &stdin_watcher); |
… | |
… | |
77 | on event-based programming, nor will it introduce event-based programming |
77 | on event-based programming, nor will it introduce event-based programming |
78 | with libev. |
78 | with libev. |
79 | |
79 | |
80 | Familiarity with event based programming techniques in general is assumed |
80 | Familiarity with event based programming techniques in general is assumed |
81 | throughout this document. |
81 | throughout this document. |
|
|
82 | |
|
|
83 | =head1 WHAT TO READ WHEN IN A HURRY |
|
|
84 | |
|
|
85 | 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 |
|
|
87 | 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 |
|
|
89 | C<ev_timer> sections in L<WATCHER TYPES>. |
82 | |
90 | |
83 | =head1 ABOUT LIBEV |
91 | =head1 ABOUT LIBEV |
84 | |
92 | |
85 | Libev is an event loop: you register interest in certain events (such as a |
93 | Libev is an event loop: you register interest in certain events (such as a |
86 | file descriptor being readable or a timeout occurring), and it will manage |
94 | file descriptor being readable or a timeout occurring), and it will manage |
… | |
… | |
293 | ... |
301 | ... |
294 | ev_set_syserr_cb (fatal_error); |
302 | ev_set_syserr_cb (fatal_error); |
295 | |
303 | |
296 | =back |
304 | =back |
297 | |
305 | |
298 | =head1 FUNCTIONS CONTROLLING THE EVENT LOOP |
306 | =head1 FUNCTIONS CONTROLLING EVENT LOOPS |
299 | |
307 | |
300 | An event loop is described by a C<struct ev_loop *> (the C<struct> is |
308 | An event loop is described by a C<struct ev_loop *> (the C<struct> is |
301 | I<not> optional in this case unless libev 3 compatibility is disabled, as |
309 | I<not> optional in this case unless libev 3 compatibility is disabled, as |
302 | libev 3 had an C<ev_loop> function colliding with the struct name). |
310 | libev 3 had an C<ev_loop> function colliding with the struct name). |
303 | |
311 | |
304 | The library knows two types of such loops, the I<default> loop, which |
312 | The library knows two types of such loops, the I<default> loop, which |
305 | supports signals and child events, and dynamically created event loops |
313 | supports child process events, and dynamically created event loops which |
306 | which do not. |
314 | do not. |
307 | |
315 | |
308 | =over 4 |
316 | =over 4 |
309 | |
317 | |
310 | =item struct ev_loop *ev_default_loop (unsigned int flags) |
318 | =item struct ev_loop *ev_default_loop (unsigned int flags) |
311 | |
319 | |
312 | This will initialise the default event loop if it hasn't been initialised |
320 | This returns the "default" event loop object, which is what you should |
313 | yet and return it. If the default loop could not be initialised, returns |
321 | normally use when you just need "the event loop". Event loop objects and |
314 | false. If it already was initialised it simply returns it (and ignores the |
322 | the C<flags> parameter are described in more detail in the entry for |
315 | flags. If that is troubling you, check C<ev_backend ()> afterwards). |
323 | C<ev_loop_new>. |
|
|
324 | |
|
|
325 | If the default loop is already initialised then this function simply |
|
|
326 | returns it (and ignores the flags. If that is troubling you, check |
|
|
327 | C<ev_backend ()> afterwards). Otherwise it will create it with the given |
|
|
328 | flags, which should almost always be C<0>, unless the caller is also the |
|
|
329 | one calling C<ev_run> or otherwise qualifies as "the main program". |
316 | |
330 | |
317 | If you don't know what event loop to use, use the one returned from this |
331 | If you don't know what event loop to use, use the one returned from this |
318 | function. |
332 | function (or via the C<EV_DEFAULT> macro). |
319 | |
333 | |
320 | Note that this function is I<not> thread-safe, so if you want to use it |
334 | Note that this function is I<not> thread-safe, so if you want to use it |
321 | from multiple threads, you have to lock (note also that this is unlikely, |
335 | from multiple threads, you have to employ some kind of mutex (note also |
322 | as loops cannot be shared easily between threads anyway). |
336 | that this case is unlikely, as loops cannot be shared easily between |
|
|
337 | threads anyway). |
323 | |
338 | |
324 | The default loop is the only loop that can handle C<ev_signal> and |
339 | The default loop is the only loop that can handle C<ev_child> watchers, |
325 | C<ev_child> watchers, and to do this, it always registers a handler |
340 | and to do this, it always registers a handler for C<SIGCHLD>. If this is |
326 | for C<SIGCHLD>. If this is a problem for your application you can either |
341 | a problem for your application you can either create a dynamic loop with |
327 | create a dynamic loop with C<ev_loop_new> that doesn't do that, or you |
342 | C<ev_loop_new> which doesn't do that, or you can simply overwrite the |
328 | can simply overwrite the C<SIGCHLD> signal handler I<after> calling |
343 | C<SIGCHLD> signal handler I<after> calling C<ev_default_init>. |
329 | C<ev_default_init>. |
344 | |
|
|
345 | Example: This is the most typical usage. |
|
|
346 | |
|
|
347 | if (!ev_default_loop (0)) |
|
|
348 | fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?"); |
|
|
349 | |
|
|
350 | Example: Restrict libev to the select and poll backends, and do not allow |
|
|
351 | environment settings to be taken into account: |
|
|
352 | |
|
|
353 | ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV); |
|
|
354 | |
|
|
355 | =item struct ev_loop *ev_loop_new (unsigned int flags) |
|
|
356 | |
|
|
357 | This will create and initialise a new event loop object. If the loop |
|
|
358 | could not be initialised, returns false. |
|
|
359 | |
|
|
360 | Note that this function I<is> thread-safe, and one common way to use |
|
|
361 | libev with threads is indeed to create one loop per thread, and using the |
|
|
362 | default loop in the "main" or "initial" thread. |
330 | |
363 | |
331 | The flags argument can be used to specify special behaviour or specific |
364 | The flags argument can be used to specify special behaviour or specific |
332 | backends to use, and is usually specified as C<0> (or C<EVFLAG_AUTO>). |
365 | backends to use, and is usually specified as C<0> (or C<EVFLAG_AUTO>). |
333 | |
366 | |
334 | The following flags are supported: |
367 | The following flags are supported: |
… | |
… | |
430 | epoll scales either O(1) or O(active_fds). |
463 | epoll scales either O(1) or O(active_fds). |
431 | |
464 | |
432 | The epoll mechanism deserves honorable mention as the most misdesigned |
465 | The epoll mechanism deserves honorable mention as the most misdesigned |
433 | of the more advanced event mechanisms: mere annoyances include silently |
466 | of the more advanced event mechanisms: mere annoyances include silently |
434 | dropping file descriptors, requiring a system call per change per file |
467 | dropping file descriptors, requiring a system call per change per file |
435 | descriptor (and unnecessary guessing of parameters), problems with dup and |
468 | descriptor (and unnecessary guessing of parameters), problems with dup, |
|
|
469 | returning before the timeout value requiring additional iterations and so |
436 | so on. The biggest issue is fork races, however - if a program forks then |
470 | on. The biggest issue is fork races, however - if a program forks then |
437 | I<both> parent and child process have to recreate the epoll set, which can |
471 | I<both> parent and child process have to recreate the epoll set, which can |
438 | take considerable time (one syscall per file descriptor) and is of course |
472 | take considerable time (one syscall per file descriptor) and is of course |
439 | hard to detect. |
473 | hard to detect. |
440 | |
474 | |
441 | Epoll is also notoriously buggy - embedding epoll fds I<should> work, but |
475 | Epoll is also notoriously buggy - embedding epoll fds I<should> work, but |
… | |
… | |
552 | If one or more of the backend flags are or'ed into the flags value, |
586 | If one or more of the backend flags are or'ed into the flags value, |
553 | then only these backends will be tried (in the reverse order as listed |
587 | then only these backends will be tried (in the reverse order as listed |
554 | here). If none are specified, all backends in C<ev_recommended_backends |
588 | here). If none are specified, all backends in C<ev_recommended_backends |
555 | ()> will be tried. |
589 | ()> will be tried. |
556 | |
590 | |
557 | Example: This is the most typical usage. |
|
|
558 | |
|
|
559 | if (!ev_default_loop (0)) |
|
|
560 | fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?"); |
|
|
561 | |
|
|
562 | Example: Restrict libev to the select and poll backends, and do not allow |
|
|
563 | environment settings to be taken into account: |
|
|
564 | |
|
|
565 | ev_default_loop (EVBACKEND_POLL | EVBACKEND_SELECT | EVFLAG_NOENV); |
|
|
566 | |
|
|
567 | Example: Use whatever libev has to offer, but make sure that kqueue is |
|
|
568 | used if available (warning, breaks stuff, best use only with your own |
|
|
569 | private event loop and only if you know the OS supports your types of |
|
|
570 | fds): |
|
|
571 | |
|
|
572 | ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE); |
|
|
573 | |
|
|
574 | =item struct ev_loop *ev_loop_new (unsigned int flags) |
|
|
575 | |
|
|
576 | Similar to C<ev_default_loop>, but always creates a new event loop that is |
|
|
577 | always distinct from the default loop. |
|
|
578 | |
|
|
579 | Note that this function I<is> thread-safe, and one common way to use |
|
|
580 | libev with threads is indeed to create one loop per thread, and using the |
|
|
581 | default loop in the "main" or "initial" thread. |
|
|
582 | |
|
|
583 | Example: Try to create a event loop that uses epoll and nothing else. |
591 | Example: Try to create a event loop that uses epoll and nothing else. |
584 | |
592 | |
585 | struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); |
593 | struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); |
586 | if (!epoller) |
594 | if (!epoller) |
587 | fatal ("no epoll found here, maybe it hides under your chair"); |
595 | fatal ("no epoll found here, maybe it hides under your chair"); |
588 | |
596 | |
|
|
597 | Example: Use whatever libev has to offer, but make sure that kqueue is |
|
|
598 | used if available. |
|
|
599 | |
|
|
600 | struct ev_loop *loop = ev_loop_new (ev_recommended_backends () | EVBACKEND_KQUEUE); |
|
|
601 | |
589 | =item ev_default_destroy () |
602 | =item ev_loop_destroy (loop) |
590 | |
603 | |
591 | Destroys the default loop (frees all memory and kernel state etc.). None |
604 | Destroys an event loop object (frees all memory and kernel state |
592 | of the active event watchers will be stopped in the normal sense, so |
605 | etc.). None of the active event watchers will be stopped in the normal |
593 | e.g. C<ev_is_active> might still return true. It is your responsibility to |
606 | sense, so e.g. C<ev_is_active> might still return true. It is your |
594 | either stop all watchers cleanly yourself I<before> calling this function, |
607 | responsibility to either stop all watchers cleanly yourself I<before> |
595 | or cope with the fact afterwards (which is usually the easiest thing, you |
608 | calling this function, or cope with the fact afterwards (which is usually |
596 | can just ignore the watchers and/or C<free ()> them for example). |
609 | the easiest thing, you can just ignore the watchers and/or C<free ()> them |
|
|
610 | for example). |
597 | |
611 | |
598 | Note that certain global state, such as signal state (and installed signal |
612 | Note that certain global state, such as signal state (and installed signal |
599 | handlers), will not be freed by this function, and related watchers (such |
613 | handlers), will not be freed by this function, and related watchers (such |
600 | as signal and child watchers) would need to be stopped manually. |
614 | as signal and child watchers) would need to be stopped manually. |
601 | |
615 | |
602 | In general it is not advisable to call this function except in the |
616 | This function is normally used on loop objects allocated by |
603 | rare occasion where you really need to free e.g. the signal handling |
617 | C<ev_loop_new>, but it can also be used on the default loop returned by |
|
|
618 | C<ev_default_loop>, in which case it is not thread-safe. |
|
|
619 | |
|
|
620 | Note that it is not advisable to call this function on the default loop |
|
|
621 | except in the rare occasion where you really need to free it's resources. |
604 | pipe fds. If you need dynamically allocated loops it is better to use |
622 | If you need dynamically allocated loops it is better to use C<ev_loop_new> |
605 | C<ev_loop_new> and C<ev_loop_destroy>. |
623 | and C<ev_loop_destroy>. |
606 | |
624 | |
607 | =item ev_loop_destroy (loop) |
625 | =item ev_loop_fork (loop) |
608 | |
626 | |
609 | Like C<ev_default_destroy>, but destroys an event loop created by an |
|
|
610 | earlier call to C<ev_loop_new>. |
|
|
611 | |
|
|
612 | =item ev_default_fork () |
|
|
613 | |
|
|
614 | This function sets a flag that causes subsequent C<ev_run> iterations |
627 | This function sets a flag that causes subsequent C<ev_run> iterations to |
615 | to reinitialise the kernel state for backends that have one. Despite the |
628 | reinitialise the kernel state for backends that have one. Despite the |
616 | name, you can call it anytime, but it makes most sense after forking, in |
629 | name, you can call it anytime, but it makes most sense after forking, in |
617 | the child process (or both child and parent, but that again makes little |
630 | the child process. You I<must> call it (or use C<EVFLAG_FORKCHECK>) in the |
618 | sense). You I<must> call it in the child before using any of the libev |
631 | child before resuming or calling C<ev_run>. |
619 | functions, and it will only take effect at the next C<ev_run> iteration. |
|
|
620 | |
632 | |
621 | Again, you I<have> to call it on I<any> loop that you want to re-use after |
633 | Again, you I<have> to call it on I<any> loop that you want to re-use after |
622 | a fork, I<even if you do not plan to use the loop in the parent>. This is |
634 | a fork, I<even if you do not plan to use the loop in the parent>. This is |
623 | because some kernel interfaces *cough* I<kqueue> *cough* do funny things |
635 | because some kernel interfaces *cough* I<kqueue> *cough* do funny things |
624 | during fork. |
636 | during fork. |
… | |
… | |
629 | call it at all (in fact, C<epoll> is so badly broken that it makes a |
641 | call it at all (in fact, C<epoll> is so badly broken that it makes a |
630 | difference, but libev will usually detect this case on its own and do a |
642 | difference, but libev will usually detect this case on its own and do a |
631 | costly reset of the backend). |
643 | costly reset of the backend). |
632 | |
644 | |
633 | The function itself is quite fast and it's usually not a problem to call |
645 | The function itself is quite fast and it's usually not a problem to call |
634 | it just in case after a fork. To make this easy, the function will fit in |
646 | it just in case after a fork. |
635 | quite nicely into a call to C<pthread_atfork>: |
|
|
636 | |
647 | |
|
|
648 | Example: Automate calling C<ev_loop_fork> on the default loop when |
|
|
649 | using pthreads. |
|
|
650 | |
|
|
651 | static void |
|
|
652 | post_fork_child (void) |
|
|
653 | { |
|
|
654 | ev_loop_fork (EV_DEFAULT); |
|
|
655 | } |
|
|
656 | |
|
|
657 | ... |
637 | pthread_atfork (0, 0, ev_default_fork); |
658 | pthread_atfork (0, 0, post_fork_child); |
638 | |
|
|
639 | =item ev_loop_fork (loop) |
|
|
640 | |
|
|
641 | Like C<ev_default_fork>, but acts on an event loop created by |
|
|
642 | C<ev_loop_new>. Yes, you have to call this on every allocated event loop |
|
|
643 | after fork that you want to re-use in the child, and how you keep track of |
|
|
644 | them is entirely your own problem. |
|
|
645 | |
659 | |
646 | =item int ev_is_default_loop (loop) |
660 | =item int ev_is_default_loop (loop) |
647 | |
661 | |
648 | Returns true when the given loop is, in fact, the default loop, and false |
662 | Returns true when the given loop is, in fact, the default loop, and false |
649 | otherwise. |
663 | otherwise. |
… | |
… | |
810 | Can be used to make a call to C<ev_run> return early (but only after it |
824 | Can be used to make a call to C<ev_run> return early (but only after it |
811 | has processed all outstanding events). The C<how> argument must be either |
825 | has processed all outstanding events). The C<how> argument must be either |
812 | C<EVBREAK_ONE>, which will make the innermost C<ev_run> call return, or |
826 | C<EVBREAK_ONE>, which will make the innermost C<ev_run> call return, or |
813 | C<EVBREAK_ALL>, which will make all nested C<ev_run> calls return. |
827 | C<EVBREAK_ALL>, which will make all nested C<ev_run> calls return. |
814 | |
828 | |
815 | This "unloop state" will be cleared when entering C<ev_run> again. |
829 | This "break state" will be cleared when entering C<ev_run> again. |
816 | |
830 | |
817 | It is safe to call C<ev_break> from outside any C<ev_run> calls. ##TODO## |
831 | It is safe to call C<ev_break> from outside any C<ev_run> calls, too. |
818 | |
832 | |
819 | =item ev_ref (loop) |
833 | =item ev_ref (loop) |
820 | |
834 | |
821 | =item ev_unref (loop) |
835 | =item ev_unref (loop) |
822 | |
836 | |
… | |
… | |
1107 | =item C<EV_FORK> |
1121 | =item C<EV_FORK> |
1108 | |
1122 | |
1109 | The event loop has been resumed in the child process after fork (see |
1123 | The event loop has been resumed in the child process after fork (see |
1110 | C<ev_fork>). |
1124 | C<ev_fork>). |
1111 | |
1125 | |
|
|
1126 | =item C<EV_CLEANUP> |
|
|
1127 | |
|
|
1128 | The event loop is about to be destroyed (see C<ev_cleanup>). |
|
|
1129 | |
1112 | =item C<EV_ASYNC> |
1130 | =item C<EV_ASYNC> |
1113 | |
1131 | |
1114 | The given async watcher has been asynchronously notified (see C<ev_async>). |
1132 | The given async watcher has been asynchronously notified (see C<ev_async>). |
1115 | |
1133 | |
1116 | =item C<EV_CUSTOM> |
1134 | =item C<EV_CUSTOM> |
… | |
… | |
1137 | programs, though, as the fd could already be closed and reused for another |
1155 | programs, though, as the fd could already be closed and reused for another |
1138 | thing, so beware. |
1156 | thing, so beware. |
1139 | |
1157 | |
1140 | =back |
1158 | =back |
1141 | |
1159 | |
1142 | =head2 WATCHER STATES |
|
|
1143 | |
|
|
1144 | There are various watcher states mentioned throughout this manual - |
|
|
1145 | active, pending and so on. In this section these states and the rules to |
|
|
1146 | transition between them will be described in more detail - and while these |
|
|
1147 | rules might look complicated, they usually do "the right thing". |
|
|
1148 | |
|
|
1149 | =over 4 |
|
|
1150 | |
|
|
1151 | =item initialiased |
|
|
1152 | |
|
|
1153 | Before a watcher can be registered with the event looop it has to be |
|
|
1154 | initialised. This can be done with a call to C<ev_TYPE_init>, or calls to |
|
|
1155 | C<ev_init> followed by the watcher-specific C<ev_TYPE_set> function. |
|
|
1156 | |
|
|
1157 | In this state it is simply some block of memory that is suitable for use |
|
|
1158 | in an event loop. It can be moved around, freed, reused etc. at will. |
|
|
1159 | |
|
|
1160 | =item started/running/active |
|
|
1161 | |
|
|
1162 | Once a watcher has been started with a call to C<ev_TYPE_start> it becomes |
|
|
1163 | property of the event loop, and is actively waiting for events. While in |
|
|
1164 | this state it cannot be accessed (except in a few documented ways), moved, |
|
|
1165 | freed or anything else - the only legal thing is to keep a pointer to it, |
|
|
1166 | and call libev functions on it that are documented to work on active watchers. |
|
|
1167 | |
|
|
1168 | =item pending |
|
|
1169 | |
|
|
1170 | If a watcher is active and libev determines that an event it is interested |
|
|
1171 | in has occurred (such as a timer expiring), it will become pending. It will |
|
|
1172 | stay in this pending state until either it is stopped or its callback is |
|
|
1173 | about to be invoked, so it is not normally pending inside the watcher |
|
|
1174 | callback. |
|
|
1175 | |
|
|
1176 | The watcher might or might not be active while it is pending (for example, |
|
|
1177 | an expired non-repeating timer can be pending but no longer active). If it |
|
|
1178 | is stopped, it can be freely accessed (e.g. by calling C<ev_TYPE_set>), |
|
|
1179 | but it is still property of the event loop at this time, so cannot be |
|
|
1180 | moved, freed or reused. And if it is active the rules described in the |
|
|
1181 | previous item still apply. |
|
|
1182 | |
|
|
1183 | It is also possible to feed an event on a watcher that is not active (e.g. |
|
|
1184 | via C<ev_feed_event>), in which case it becomes pending without being |
|
|
1185 | active. |
|
|
1186 | |
|
|
1187 | =item stopped |
|
|
1188 | |
|
|
1189 | A watcher can be stopped implicitly by libev (in which case it might still |
|
|
1190 | be pending), or explicitly by calling its C<ev_TYPE_stop> function. The |
|
|
1191 | latter will clear any pending state the watcher might be in, regardless |
|
|
1192 | of whether it was active or not, so stopping a watcher explicitly before |
|
|
1193 | freeing it is often a good idea. |
|
|
1194 | |
|
|
1195 | While stopped (and not pending) the watcher is essentially in the |
|
|
1196 | initialised state, that is it can be reused, moved, modified in any way |
|
|
1197 | you wish. |
|
|
1198 | |
|
|
1199 | =back |
|
|
1200 | |
|
|
1201 | =head2 GENERIC WATCHER FUNCTIONS |
1160 | =head2 GENERIC WATCHER FUNCTIONS |
1202 | |
1161 | |
1203 | =over 4 |
1162 | =over 4 |
1204 | |
1163 | |
1205 | =item C<ev_init> (ev_TYPE *watcher, callback) |
1164 | =item C<ev_init> (ev_TYPE *watcher, callback) |
… | |
… | |
1346 | |
1305 | |
1347 | See also C<ev_feed_fd_event> and C<ev_feed_signal_event> for related |
1306 | See also C<ev_feed_fd_event> and C<ev_feed_signal_event> for related |
1348 | functions that do not need a watcher. |
1307 | functions that do not need a watcher. |
1349 | |
1308 | |
1350 | =back |
1309 | =back |
1351 | |
|
|
1352 | |
1310 | |
1353 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
1311 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
1354 | |
1312 | |
1355 | Each watcher has, by default, a member C<void *data> that you can change |
1313 | Each watcher has, by default, a member C<void *data> that you can change |
1356 | and read at any time: libev will completely ignore it. This can be used |
1314 | and read at any time: libev will completely ignore it. This can be used |
… | |
… | |
1412 | t2_cb (EV_P_ ev_timer *w, int revents) |
1370 | t2_cb (EV_P_ ev_timer *w, int revents) |
1413 | { |
1371 | { |
1414 | struct my_biggy big = (struct my_biggy *) |
1372 | struct my_biggy big = (struct my_biggy *) |
1415 | (((char *)w) - offsetof (struct my_biggy, t2)); |
1373 | (((char *)w) - offsetof (struct my_biggy, t2)); |
1416 | } |
1374 | } |
|
|
1375 | |
|
|
1376 | =head2 WATCHER STATES |
|
|
1377 | |
|
|
1378 | There are various watcher states mentioned throughout this manual - |
|
|
1379 | active, pending and so on. In this section these states and the rules to |
|
|
1380 | transition between them will be described in more detail - and while these |
|
|
1381 | rules might look complicated, they usually do "the right thing". |
|
|
1382 | |
|
|
1383 | =over 4 |
|
|
1384 | |
|
|
1385 | =item initialiased |
|
|
1386 | |
|
|
1387 | Before a watcher can be registered with the event looop it has to be |
|
|
1388 | initialised. This can be done with a call to C<ev_TYPE_init>, or calls to |
|
|
1389 | C<ev_init> followed by the watcher-specific C<ev_TYPE_set> function. |
|
|
1390 | |
|
|
1391 | In this state it is simply some block of memory that is suitable for use |
|
|
1392 | in an event loop. It can be moved around, freed, reused etc. at will. |
|
|
1393 | |
|
|
1394 | =item started/running/active |
|
|
1395 | |
|
|
1396 | Once a watcher has been started with a call to C<ev_TYPE_start> it becomes |
|
|
1397 | property of the event loop, and is actively waiting for events. While in |
|
|
1398 | this state it cannot be accessed (except in a few documented ways), moved, |
|
|
1399 | freed or anything else - the only legal thing is to keep a pointer to it, |
|
|
1400 | and call libev functions on it that are documented to work on active watchers. |
|
|
1401 | |
|
|
1402 | =item pending |
|
|
1403 | |
|
|
1404 | If a watcher is active and libev determines that an event it is interested |
|
|
1405 | in has occurred (such as a timer expiring), it will become pending. It will |
|
|
1406 | stay in this pending state until either it is stopped or its callback is |
|
|
1407 | about to be invoked, so it is not normally pending inside the watcher |
|
|
1408 | callback. |
|
|
1409 | |
|
|
1410 | The watcher might or might not be active while it is pending (for example, |
|
|
1411 | an expired non-repeating timer can be pending but no longer active). If it |
|
|
1412 | is stopped, it can be freely accessed (e.g. by calling C<ev_TYPE_set>), |
|
|
1413 | but it is still property of the event loop at this time, so cannot be |
|
|
1414 | moved, freed or reused. And if it is active the rules described in the |
|
|
1415 | previous item still apply. |
|
|
1416 | |
|
|
1417 | It is also possible to feed an event on a watcher that is not active (e.g. |
|
|
1418 | via C<ev_feed_event>), in which case it becomes pending without being |
|
|
1419 | active. |
|
|
1420 | |
|
|
1421 | =item stopped |
|
|
1422 | |
|
|
1423 | A watcher can be stopped implicitly by libev (in which case it might still |
|
|
1424 | be pending), or explicitly by calling its C<ev_TYPE_stop> function. The |
|
|
1425 | latter will clear any pending state the watcher might be in, regardless |
|
|
1426 | of whether it was active or not, so stopping a watcher explicitly before |
|
|
1427 | freeing it is often a good idea. |
|
|
1428 | |
|
|
1429 | While stopped (and not pending) the watcher is essentially in the |
|
|
1430 | initialised state, that is it can be reused, moved, modified in any way |
|
|
1431 | you wish. |
|
|
1432 | |
|
|
1433 | =back |
1417 | |
1434 | |
1418 | =head2 WATCHER PRIORITY MODELS |
1435 | =head2 WATCHER PRIORITY MODELS |
1419 | |
1436 | |
1420 | Many event loops support I<watcher priorities>, which are usually small |
1437 | Many event loops support I<watcher priorities>, which are usually small |
1421 | integers that influence the ordering of event callback invocation |
1438 | integers that influence the ordering of event callback invocation |
… | |
… | |
3075 | disadvantage of having to use multiple event loops (which do not support |
3092 | disadvantage of having to use multiple event loops (which do not support |
3076 | signal watchers). |
3093 | signal watchers). |
3077 | |
3094 | |
3078 | When this is not possible, or you want to use the default loop for |
3095 | When this is not possible, or you want to use the default loop for |
3079 | other reasons, then in the process that wants to start "fresh", call |
3096 | other reasons, then in the process that wants to start "fresh", call |
3080 | C<ev_default_destroy ()> followed by C<ev_default_loop (...)>. Destroying |
3097 | C<ev_loop_destroy (EV_DEFAULT)> followed by C<ev_default_loop (...)>. |
3081 | the default loop will "orphan" (not stop) all registered watchers, so you |
3098 | Destroying the default loop will "orphan" (not stop) all registered |
3082 | have to be careful not to execute code that modifies those watchers. Note |
3099 | watchers, so you have to be careful not to execute code that modifies |
3083 | also that in that case, you have to re-register any signal watchers. |
3100 | those watchers. Note also that in that case, you have to re-register any |
|
|
3101 | signal watchers. |
3084 | |
3102 | |
3085 | =head3 Watcher-Specific Functions and Data Members |
3103 | =head3 Watcher-Specific Functions and Data Members |
3086 | |
3104 | |
3087 | =over 4 |
3105 | =over 4 |
3088 | |
3106 | |
3089 | =item ev_fork_init (ev_signal *, callback) |
3107 | =item ev_fork_init (ev_fork *, callback) |
3090 | |
3108 | |
3091 | Initialises and configures the fork watcher - it has no parameters of any |
3109 | Initialises and configures the fork watcher - it has no parameters of any |
3092 | kind. There is a C<ev_fork_set> macro, but using it is utterly pointless, |
3110 | kind. There is a C<ev_fork_set> macro, but using it is utterly pointless, |
3093 | believe me. |
3111 | really. |
3094 | |
3112 | |
3095 | =back |
3113 | =back |
|
|
3114 | |
|
|
3115 | |
|
|
3116 | =head2 C<ev_cleanup> - even the best things end |
|
|
3117 | |
|
|
3118 | Cleanup watchers are called just before the event loop is being destroyed |
|
|
3119 | by a call to C<ev_loop_destroy>. |
|
|
3120 | |
|
|
3121 | While there is no guarantee that the event loop gets destroyed, cleanup |
|
|
3122 | watchers provide a convenient method to install cleanup hooks for your |
|
|
3123 | program, worker threads and so on - you just to make sure to destroy the |
|
|
3124 | loop when you want them to be invoked. |
|
|
3125 | |
|
|
3126 | Cleanup watchers are invoked in the same way as any other watcher. Unlike |
|
|
3127 | all other watchers, they do not keep a reference to the event loop (which |
|
|
3128 | makes a lot of sense if you think about it). Like all other watchers, you |
|
|
3129 | can call libev functions in the callback, except C<ev_cleanup_start>. |
|
|
3130 | |
|
|
3131 | =head3 Watcher-Specific Functions and Data Members |
|
|
3132 | |
|
|
3133 | =over 4 |
|
|
3134 | |
|
|
3135 | =item ev_cleanup_init (ev_cleanup *, callback) |
|
|
3136 | |
|
|
3137 | Initialises and configures the cleanup watcher - it has no parameters of |
|
|
3138 | any kind. There is a C<ev_cleanup_set> macro, but using it is utterly |
|
|
3139 | pointless, I assure you. |
|
|
3140 | |
|
|
3141 | =back |
|
|
3142 | |
|
|
3143 | Example: Register an atexit handler to destroy the default loop, so any |
|
|
3144 | cleanup functions are called. |
|
|
3145 | |
|
|
3146 | static void |
|
|
3147 | program_exits (void) |
|
|
3148 | { |
|
|
3149 | ev_loop_destroy (EV_DEFAULT_UC); |
|
|
3150 | } |
|
|
3151 | |
|
|
3152 | ... |
|
|
3153 | atexit (program_exits); |
3096 | |
3154 | |
3097 | |
3155 | |
3098 | =head2 C<ev_async> - how to wake up an event loop |
3156 | =head2 C<ev_async> - how to wake up an event loop |
3099 | |
3157 | |
3100 | In general, you cannot use an C<ev_run> from multiple threads or other |
3158 | In general, you cannot use an C<ev_run> from multiple threads or other |
… | |
… | |
4707 | structure (guaranteed by POSIX but not by ISO C for example), but it also |
4765 | structure (guaranteed by POSIX but not by ISO C for example), but it also |
4708 | assumes that the same (machine) code can be used to call any watcher |
4766 | assumes that the same (machine) code can be used to call any watcher |
4709 | callback: The watcher callbacks have different type signatures, but libev |
4767 | callback: The watcher callbacks have different type signatures, but libev |
4710 | calls them using an C<ev_watcher *> internally. |
4768 | calls them using an C<ev_watcher *> internally. |
4711 | |
4769 | |
|
|
4770 | =item pointer accesses must be thread-atomic |
|
|
4771 | |
|
|
4772 | Accessing a pointer value must be atomic, it must both be readable and |
|
|
4773 | writable in one piece - this is the case on all current architectures. |
|
|
4774 | |
4712 | =item C<sig_atomic_t volatile> must be thread-atomic as well |
4775 | =item C<sig_atomic_t volatile> must be thread-atomic as well |
4713 | |
4776 | |
4714 | The type C<sig_atomic_t volatile> (or whatever is defined as |
4777 | The type C<sig_atomic_t volatile> (or whatever is defined as |
4715 | C<EV_ATOMIC_T>) must be atomic with respect to accesses from different |
4778 | C<EV_ATOMIC_T>) must be atomic with respect to accesses from different |
4716 | threads. This is not part of the specification for C<sig_atomic_t>, but is |
4779 | threads. This is not part of the specification for C<sig_atomic_t>, but is |
… | |
… | |
4822 | =back |
4885 | =back |
4823 | |
4886 | |
4824 | |
4887 | |
4825 | =head1 PORTING FROM LIBEV 3.X TO 4.X |
4888 | =head1 PORTING FROM LIBEV 3.X TO 4.X |
4826 | |
4889 | |
4827 | The major version 4 introduced some minor incompatible changes to the API. |
4890 | The major version 4 introduced some incompatible changes to the API. |
4828 | |
4891 | |
4829 | At the moment, the C<ev.h> header file tries to implement superficial |
4892 | At the moment, the C<ev.h> header file provides compatibility definitions |
4830 | compatibility, so most programs should still compile. Those might be |
4893 | for all changes, so most programs should still compile. The compatibility |
4831 | removed in later versions of libev, so better update early than late. |
4894 | layer might be removed in later versions of libev, so better update to the |
|
|
4895 | new API early than late. |
4832 | |
4896 | |
4833 | =over 4 |
4897 | =over 4 |
|
|
4898 | |
|
|
4899 | =item C<EV_COMPAT3> backwards compatibility mechanism |
|
|
4900 | |
|
|
4901 | The backward compatibility mechanism can be controlled by |
|
|
4902 | C<EV_COMPAT3>. See L<PREPROCESSOR SYMBOLS/MACROS> in the L<EMBEDDING> |
|
|
4903 | section. |
|
|
4904 | |
|
|
4905 | =item C<ev_default_destroy> and C<ev_default_fork> have been removed |
|
|
4906 | |
|
|
4907 | These calls can be replaced easily by their C<ev_loop_xxx> counterparts: |
|
|
4908 | |
|
|
4909 | ev_loop_destroy (EV_DEFAULT_UC); |
|
|
4910 | ev_loop_fork (EV_DEFAULT); |
4834 | |
4911 | |
4835 | =item function/symbol renames |
4912 | =item function/symbol renames |
4836 | |
4913 | |
4837 | A number of functions and symbols have been renamed: |
4914 | A number of functions and symbols have been renamed: |
4838 | |
4915 | |
… | |
… | |
4857 | ev_loop> anymore and C<EV_TIMER> now follows the same naming scheme |
4934 | ev_loop> anymore and C<EV_TIMER> now follows the same naming scheme |
4858 | as all other watcher types. Note that C<ev_loop_fork> is still called |
4935 | as all other watcher types. Note that C<ev_loop_fork> is still called |
4859 | C<ev_loop_fork> because it would otherwise clash with the C<ev_fork> |
4936 | C<ev_loop_fork> because it would otherwise clash with the C<ev_fork> |
4860 | typedef. |
4937 | typedef. |
4861 | |
4938 | |
4862 | =item C<EV_COMPAT3> backwards compatibility mechanism |
|
|
4863 | |
|
|
4864 | The backward compatibility mechanism can be controlled by |
|
|
4865 | C<EV_COMPAT3>. See L<PREPROCESSOR SYMBOLS/MACROS> in the L<EMBEDDING> |
|
|
4866 | section. |
|
|
4867 | |
|
|
4868 | =item C<EV_MINIMAL> mechanism replaced by C<EV_FEATURES> |
4939 | =item C<EV_MINIMAL> mechanism replaced by C<EV_FEATURES> |
4869 | |
4940 | |
4870 | The preprocessor symbol C<EV_MINIMAL> has been replaced by a different |
4941 | The preprocessor symbol C<EV_MINIMAL> has been replaced by a different |
4871 | mechanism, C<EV_FEATURES>. Programs using C<EV_MINIMAL> usually compile |
4942 | mechanism, C<EV_FEATURES>. Programs using C<EV_MINIMAL> usually compile |
4872 | and work, but the library code will of course be larger. |
4943 | and work, but the library code will of course be larger. |
… | |
… | |
4946 | |
5017 | |
4947 | =back |
5018 | =back |
4948 | |
5019 | |
4949 | =head1 AUTHOR |
5020 | =head1 AUTHOR |
4950 | |
5021 | |
4951 | Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael Magnusson. |
5022 | Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael |
|
|
5023 | Magnusson and Emanuele Giaquinta. |
4952 | |
5024 | |