… | |
… | |
4 | |
4 | |
5 | =head1 SYNOPSIS |
5 | =head1 SYNOPSIS |
6 | |
6 | |
7 | #include <ev.h> |
7 | #include <ev.h> |
8 | |
8 | |
9 | =head1 EXAMPLE PROGRAM |
9 | =head2 EXAMPLE PROGRAM |
10 | |
10 | |
11 | #include <ev.h> |
11 | #include <ev.h> |
12 | |
12 | |
13 | ev_io stdin_watcher; |
13 | ev_io stdin_watcher; |
14 | ev_timer timeout_watcher; |
14 | ev_timer timeout_watcher; |
… | |
… | |
65 | You register interest in certain events by registering so-called I<event |
65 | You register interest in certain events by registering so-called I<event |
66 | watchers>, which are relatively small C structures you initialise with the |
66 | watchers>, which are relatively small C structures you initialise with the |
67 | details of the event, and then hand it over to libev by I<starting> the |
67 | details of the event, and then hand it over to libev by I<starting> the |
68 | watcher. |
68 | watcher. |
69 | |
69 | |
70 | =head1 FEATURES |
70 | =head2 FEATURES |
71 | |
71 | |
72 | Libev supports C<select>, C<poll>, the Linux-specific C<epoll>, the |
72 | Libev supports C<select>, C<poll>, the Linux-specific C<epoll>, the |
73 | BSD-specific C<kqueue> and the Solaris-specific event port mechanisms |
73 | BSD-specific C<kqueue> and the Solaris-specific event port mechanisms |
74 | for file descriptor events (C<ev_io>), the Linux C<inotify> interface |
74 | for file descriptor events (C<ev_io>), the Linux C<inotify> interface |
75 | (for C<ev_stat>), relative timers (C<ev_timer>), absolute timers |
75 | (for C<ev_stat>), relative timers (C<ev_timer>), absolute timers |
… | |
… | |
82 | |
82 | |
83 | It also is quite fast (see this |
83 | It also is quite fast (see this |
84 | L<benchmark|http://libev.schmorp.de/bench.html> comparing it to libevent |
84 | L<benchmark|http://libev.schmorp.de/bench.html> comparing it to libevent |
85 | for example). |
85 | for example). |
86 | |
86 | |
87 | =head1 CONVENTIONS |
87 | =head2 CONVENTIONS |
88 | |
88 | |
89 | Libev is very configurable. In this manual the default configuration will |
89 | Libev is very configurable. In this manual the default configuration will |
90 | be described, which supports multiple event loops. For more info about |
90 | be described, which supports multiple event loops. For more info about |
91 | various configuration options please have a look at B<EMBED> section in |
91 | various configuration options please have a look at B<EMBED> section in |
92 | this manual. If libev was configured without support for multiple event |
92 | this manual. If libev was configured without support for multiple event |
93 | loops, then all functions taking an initial argument of name C<loop> |
93 | loops, then all functions taking an initial argument of name C<loop> |
94 | (which is always of type C<struct ev_loop *>) will not have this argument. |
94 | (which is always of type C<struct ev_loop *>) will not have this argument. |
95 | |
95 | |
96 | =head1 TIME REPRESENTATION |
96 | =head2 TIME REPRESENTATION |
97 | |
97 | |
98 | Libev represents time as a single floating point number, representing the |
98 | Libev represents time as a single floating point number, representing the |
99 | (fractional) number of seconds since the (POSIX) epoch (somewhere near |
99 | (fractional) number of seconds since the (POSIX) epoch (somewhere near |
100 | the beginning of 1970, details are complicated, don't ask). This type is |
100 | the beginning of 1970, details are complicated, don't ask). This type is |
101 | called C<ev_tstamp>, which is what you should use too. It usually aliases |
101 | called C<ev_tstamp>, which is what you should use too. It usually aliases |
… | |
… | |
260 | flags. If that is troubling you, check C<ev_backend ()> afterwards). |
260 | flags. If that is troubling you, check C<ev_backend ()> afterwards). |
261 | |
261 | |
262 | If you don't know what event loop to use, use the one returned from this |
262 | If you don't know what event loop to use, use the one returned from this |
263 | function. |
263 | function. |
264 | |
264 | |
|
|
265 | The default loop is the only loop that can handle C<ev_signal> and |
|
|
266 | C<ev_child> watchers, and to do this, it always registers a handler |
|
|
267 | for C<SIGCHLD>. If this is a problem for your app you can either |
|
|
268 | create a dynamic loop with C<ev_loop_new> that doesn't do that, or you |
|
|
269 | can simply overwrite the C<SIGCHLD> signal handler I<after> calling |
|
|
270 | C<ev_default_init>. |
|
|
271 | |
265 | The flags argument can be used to specify special behaviour or specific |
272 | The flags argument can be used to specify special behaviour or specific |
266 | backends to use, and is usually specified as C<0> (or C<EVFLAG_AUTO>). |
273 | backends to use, and is usually specified as C<0> (or C<EVFLAG_AUTO>). |
267 | |
274 | |
268 | The following flags are supported: |
275 | The following flags are supported: |
269 | |
276 | |
… | |
… | |
403 | While this backend scales well, it requires one system call per active |
410 | While this backend scales well, it requires one system call per active |
404 | file descriptor per loop iteration. For small and medium numbers of file |
411 | file descriptor per loop iteration. For small and medium numbers of file |
405 | descriptors a "slow" C<EVBACKEND_SELECT> or C<EVBACKEND_POLL> backend |
412 | descriptors a "slow" C<EVBACKEND_SELECT> or C<EVBACKEND_POLL> backend |
406 | might perform better. |
413 | might perform better. |
407 | |
414 | |
|
|
415 | On the positive side, ignoring the spurious readyness notifications, this |
|
|
416 | backend actually performed to specification in all tests and is fully |
|
|
417 | embeddable, which is a rare feat among the OS-specific backends. |
|
|
418 | |
408 | =item C<EVBACKEND_ALL> |
419 | =item C<EVBACKEND_ALL> |
409 | |
420 | |
410 | Try all backends (even potentially broken ones that wouldn't be tried |
421 | Try all backends (even potentially broken ones that wouldn't be tried |
411 | with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as |
422 | with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as |
412 | C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>. |
423 | C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>. |
… | |
… | |
414 | It is definitely not recommended to use this flag. |
425 | It is definitely not recommended to use this flag. |
415 | |
426 | |
416 | =back |
427 | =back |
417 | |
428 | |
418 | If one or more of these are ored into the flags value, then only these |
429 | If one or more of these are ored into the flags value, then only these |
419 | backends will be tried (in the reverse order as given here). If none are |
430 | backends will be tried (in the reverse order as listed here). If none are |
420 | specified, most compiled-in backend will be tried, usually in reverse |
431 | specified, all backends in C<ev_recommended_backends ()> will be tried. |
421 | order of their flag values :) |
|
|
422 | |
432 | |
423 | The most typical usage is like this: |
433 | The most typical usage is like this: |
424 | |
434 | |
425 | if (!ev_default_loop (0)) |
435 | if (!ev_default_loop (0)) |
426 | fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?"); |
436 | fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?"); |
… | |
… | |
473 | Like C<ev_default_destroy>, but destroys an event loop created by an |
483 | Like C<ev_default_destroy>, but destroys an event loop created by an |
474 | earlier call to C<ev_loop_new>. |
484 | earlier call to C<ev_loop_new>. |
475 | |
485 | |
476 | =item ev_default_fork () |
486 | =item ev_default_fork () |
477 | |
487 | |
|
|
488 | This function sets a flag that causes subsequent C<ev_loop> iterations |
478 | This function reinitialises the kernel state for backends that have |
489 | to reinitialise the kernel state for backends that have one. Despite the |
479 | one. Despite the name, you can call it anytime, but it makes most sense |
490 | name, you can call it anytime, but it makes most sense after forking, in |
480 | after forking, in either the parent or child process (or both, but that |
491 | the child process (or both child and parent, but that again makes little |
481 | again makes little sense). |
492 | sense). You I<must> call it in the child before using any of the libev |
|
|
493 | functions, and it will only take effect at the next C<ev_loop> iteration. |
482 | |
494 | |
483 | You I<must> call this function in the child process after forking if and |
495 | On the other hand, you only need to call this function in the child |
484 | only if you want to use the event library in both processes. If you just |
496 | process if and only if you want to use the event library in the child. If |
485 | fork+exec, you don't have to call it. |
497 | you just fork+exec, you don't have to call it at all. |
486 | |
498 | |
487 | The function itself is quite fast and it's usually not a problem to call |
499 | The function itself is quite fast and it's usually not a problem to call |
488 | it just in case after a fork. To make this easy, the function will fit in |
500 | it just in case after a fork. To make this easy, the function will fit in |
489 | quite nicely into a call to C<pthread_atfork>: |
501 | quite nicely into a call to C<pthread_atfork>: |
490 | |
502 | |
491 | pthread_atfork (0, 0, ev_default_fork); |
503 | pthread_atfork (0, 0, ev_default_fork); |
492 | |
504 | |
493 | At the moment, C<EVBACKEND_SELECT> and C<EVBACKEND_POLL> are safe to use |
|
|
494 | without calling this function, so if you force one of those backends you |
|
|
495 | do not need to care. |
|
|
496 | |
|
|
497 | =item ev_loop_fork (loop) |
505 | =item ev_loop_fork (loop) |
498 | |
506 | |
499 | Like C<ev_default_fork>, but acts on an event loop created by |
507 | Like C<ev_default_fork>, but acts on an event loop created by |
500 | C<ev_loop_new>. Yes, you have to call this on every allocated event loop |
508 | C<ev_loop_new>. Yes, you have to call this on every allocated event loop |
501 | after fork, and how you do this is entirely your own problem. |
509 | after fork, and how you do this is entirely your own problem. |
|
|
510 | |
|
|
511 | =item int ev_is_default_loop (loop) |
|
|
512 | |
|
|
513 | Returns true when the given loop actually is the default loop, false otherwise. |
502 | |
514 | |
503 | =item unsigned int ev_loop_count (loop) |
515 | =item unsigned int ev_loop_count (loop) |
504 | |
516 | |
505 | Returns the count of loop iterations for the loop, which is identical to |
517 | Returns the count of loop iterations for the loop, which is identical to |
506 | the number of times libev did poll for new events. It starts at C<0> and |
518 | the number of times libev did poll for new events. It starts at C<0> and |
… | |
… | |
551 | usually a better approach for this kind of thing. |
563 | usually a better approach for this kind of thing. |
552 | |
564 | |
553 | Here are the gory details of what C<ev_loop> does: |
565 | Here are the gory details of what C<ev_loop> does: |
554 | |
566 | |
555 | - Before the first iteration, call any pending watchers. |
567 | - Before the first iteration, call any pending watchers. |
556 | * If there are no active watchers (reference count is zero), return. |
568 | * If EVFLAG_FORKCHECK was used, check for a fork. |
557 | - Queue all prepare watchers and then call all outstanding watchers. |
569 | - If a fork was detected, queue and call all fork watchers. |
|
|
570 | - Queue and call all prepare watchers. |
558 | - If we have been forked, recreate the kernel state. |
571 | - If we have been forked, recreate the kernel state. |
559 | - Update the kernel state with all outstanding changes. |
572 | - Update the kernel state with all outstanding changes. |
560 | - Update the "event loop time". |
573 | - Update the "event loop time". |
561 | - Calculate for how long to block. |
574 | - Calculate for how long to sleep or block, if at all |
|
|
575 | (active idle watchers, EVLOOP_NONBLOCK or not having |
|
|
576 | any active watchers at all will result in not sleeping). |
|
|
577 | - Sleep if the I/O and timer collect interval say so. |
562 | - Block the process, waiting for any events. |
578 | - Block the process, waiting for any events. |
563 | - Queue all outstanding I/O (fd) events. |
579 | - Queue all outstanding I/O (fd) events. |
564 | - Update the "event loop time" and do time jump handling. |
580 | - Update the "event loop time" and do time jump handling. |
565 | - Queue all outstanding timers. |
581 | - Queue all outstanding timers. |
566 | - Queue all outstanding periodics. |
582 | - Queue all outstanding periodics. |
567 | - If no events are pending now, queue all idle watchers. |
583 | - If no events are pending now, queue all idle watchers. |
568 | - Queue all check watchers. |
584 | - Queue all check watchers. |
569 | - Call all queued watchers in reverse order (i.e. check watchers first). |
585 | - Call all queued watchers in reverse order (i.e. check watchers first). |
570 | Signals and child watchers are implemented as I/O watchers, and will |
586 | Signals and child watchers are implemented as I/O watchers, and will |
571 | be handled here by queueing them when their watcher gets executed. |
587 | be handled here by queueing them when their watcher gets executed. |
572 | - If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
588 | - If ev_unloop has been called, or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
573 | were used, return, otherwise continue with step *. |
589 | were used, or there are no active watchers, return, otherwise |
|
|
590 | continue with step *. |
574 | |
591 | |
575 | Example: Queue some jobs and then loop until no events are outsanding |
592 | Example: Queue some jobs and then loop until no events are outstanding |
576 | anymore. |
593 | anymore. |
577 | |
594 | |
578 | ... queue jobs here, make sure they register event watchers as long |
595 | ... queue jobs here, make sure they register event watchers as long |
579 | ... as they still have work to do (even an idle watcher will do..) |
596 | ... as they still have work to do (even an idle watcher will do..) |
580 | ev_loop (my_loop, 0); |
597 | ev_loop (my_loop, 0); |
… | |
… | |
584 | |
601 | |
585 | Can be used to make a call to C<ev_loop> return early (but only after it |
602 | Can be used to make a call to C<ev_loop> return early (but only after it |
586 | has processed all outstanding events). The C<how> argument must be either |
603 | has processed all outstanding events). The C<how> argument must be either |
587 | C<EVUNLOOP_ONE>, which will make the innermost C<ev_loop> call return, or |
604 | C<EVUNLOOP_ONE>, which will make the innermost C<ev_loop> call return, or |
588 | C<EVUNLOOP_ALL>, which will make all nested C<ev_loop> calls return. |
605 | C<EVUNLOOP_ALL>, which will make all nested C<ev_loop> calls return. |
|
|
606 | |
|
|
607 | This "unloop state" will be cleared when entering C<ev_loop> again. |
589 | |
608 | |
590 | =item ev_ref (loop) |
609 | =item ev_ref (loop) |
591 | |
610 | |
592 | =item ev_unref (loop) |
611 | =item ev_unref (loop) |
593 | |
612 | |
… | |
… | |
598 | returning, ev_unref() after starting, and ev_ref() before stopping it. For |
617 | returning, ev_unref() after starting, and ev_ref() before stopping it. For |
599 | example, libev itself uses this for its internal signal pipe: It is not |
618 | example, libev itself uses this for its internal signal pipe: It is not |
600 | visible to the libev user and should not keep C<ev_loop> from exiting if |
619 | visible to the libev user and should not keep C<ev_loop> from exiting if |
601 | no event watchers registered by it are active. It is also an excellent |
620 | no event watchers registered by it are active. It is also an excellent |
602 | way to do this for generic recurring timers or from within third-party |
621 | way to do this for generic recurring timers or from within third-party |
603 | libraries. Just remember to I<unref after start> and I<ref before stop>. |
622 | libraries. Just remember to I<unref after start> and I<ref before stop> |
|
|
623 | (but only if the watcher wasn't active before, or was active before, |
|
|
624 | respectively). |
604 | |
625 | |
605 | Example: Create a signal watcher, but keep it from keeping C<ev_loop> |
626 | Example: Create a signal watcher, but keep it from keeping C<ev_loop> |
606 | running when nothing else is active. |
627 | running when nothing else is active. |
607 | |
628 | |
608 | struct ev_signal exitsig; |
629 | struct ev_signal exitsig; |
… | |
… | |
756 | |
777 | |
757 | =item C<EV_FORK> |
778 | =item C<EV_FORK> |
758 | |
779 | |
759 | The event loop has been resumed in the child process after fork (see |
780 | The event loop has been resumed in the child process after fork (see |
760 | C<ev_fork>). |
781 | C<ev_fork>). |
|
|
782 | |
|
|
783 | =item C<EV_ASYNC> |
|
|
784 | |
|
|
785 | The given async watcher has been asynchronously notified (see C<ev_async>). |
761 | |
786 | |
762 | =item C<EV_ERROR> |
787 | =item C<EV_ERROR> |
763 | |
788 | |
764 | An unspecified error has occured, the watcher has been stopped. This might |
789 | An unspecified error has occured, the watcher has been stopped. This might |
765 | happen because the watcher could not be properly started because libev |
790 | happen because the watcher could not be properly started because libev |
… | |
… | |
983 | In general you can register as many read and/or write event watchers per |
1008 | In general you can register as many read and/or write event watchers per |
984 | fd as you want (as long as you don't confuse yourself). Setting all file |
1009 | fd as you want (as long as you don't confuse yourself). Setting all file |
985 | descriptors to non-blocking mode is also usually a good idea (but not |
1010 | descriptors to non-blocking mode is also usually a good idea (but not |
986 | required if you know what you are doing). |
1011 | required if you know what you are doing). |
987 | |
1012 | |
988 | You have to be careful with dup'ed file descriptors, though. Some backends |
|
|
989 | (the linux epoll backend is a notable example) cannot handle dup'ed file |
|
|
990 | descriptors correctly if you register interest in two or more fds pointing |
|
|
991 | to the same underlying file/socket/etc. description (that is, they share |
|
|
992 | the same underlying "file open"). |
|
|
993 | |
|
|
994 | If you must do this, then force the use of a known-to-be-good backend |
1013 | If you must do this, then force the use of a known-to-be-good backend |
995 | (at the time of this writing, this includes only C<EVBACKEND_SELECT> and |
1014 | (at the time of this writing, this includes only C<EVBACKEND_SELECT> and |
996 | C<EVBACKEND_POLL>). |
1015 | C<EVBACKEND_POLL>). |
997 | |
1016 | |
998 | Another thing you have to watch out for is that it is quite easy to |
1017 | Another thing you have to watch out for is that it is quite easy to |
… | |
… | |
1033 | |
1052 | |
1034 | =head3 The special problem of dup'ed file descriptors |
1053 | =head3 The special problem of dup'ed file descriptors |
1035 | |
1054 | |
1036 | Some backends (e.g. epoll), cannot register events for file descriptors, |
1055 | Some backends (e.g. epoll), cannot register events for file descriptors, |
1037 | but only events for the underlying file descriptions. That means when you |
1056 | but only events for the underlying file descriptions. That means when you |
1038 | have C<dup ()>'ed file descriptors and register events for them, only one |
1057 | have C<dup ()>'ed file descriptors or weirder constellations, and register |
1039 | file descriptor might actually receive events. |
1058 | events for them, only one file descriptor might actually receive events. |
1040 | |
1059 | |
1041 | There is no workaround possible except not registering events |
1060 | There is no workaround possible except not registering events |
1042 | for potentially C<dup ()>'ed file descriptors, or to resort to |
1061 | for potentially C<dup ()>'ed file descriptors, or to resort to |
1043 | C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>. |
1062 | C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>. |
1044 | |
1063 | |
… | |
… | |
1073 | =item int events [read-only] |
1092 | =item int events [read-only] |
1074 | |
1093 | |
1075 | The events being watched. |
1094 | The events being watched. |
1076 | |
1095 | |
1077 | =back |
1096 | =back |
|
|
1097 | |
|
|
1098 | =head3 Examples |
1078 | |
1099 | |
1079 | Example: Call C<stdin_readable_cb> when STDIN_FILENO has become, well |
1100 | Example: Call C<stdin_readable_cb> when STDIN_FILENO has become, well |
1080 | readable, but only once. Since it is likely line-buffered, you could |
1101 | readable, but only once. Since it is likely line-buffered, you could |
1081 | attempt to read a whole line in the callback. |
1102 | attempt to read a whole line in the callback. |
1082 | |
1103 | |
… | |
… | |
1135 | configure a timer to trigger every 10 seconds, then it will trigger at |
1156 | configure a timer to trigger every 10 seconds, then it will trigger at |
1136 | exactly 10 second intervals. If, however, your program cannot keep up with |
1157 | exactly 10 second intervals. If, however, your program cannot keep up with |
1137 | the timer (because it takes longer than those 10 seconds to do stuff) the |
1158 | the timer (because it takes longer than those 10 seconds to do stuff) the |
1138 | timer will not fire more than once per event loop iteration. |
1159 | timer will not fire more than once per event loop iteration. |
1139 | |
1160 | |
1140 | =item ev_timer_again (loop) |
1161 | =item ev_timer_again (loop, ev_timer *) |
1141 | |
1162 | |
1142 | This will act as if the timer timed out and restart it again if it is |
1163 | This will act as if the timer timed out and restart it again if it is |
1143 | repeating. The exact semantics are: |
1164 | repeating. The exact semantics are: |
1144 | |
1165 | |
1145 | If the timer is pending, its pending status is cleared. |
1166 | If the timer is pending, its pending status is cleared. |
… | |
… | |
1180 | or C<ev_timer_again> is called and determines the next timeout (if any), |
1201 | or C<ev_timer_again> is called and determines the next timeout (if any), |
1181 | which is also when any modifications are taken into account. |
1202 | which is also when any modifications are taken into account. |
1182 | |
1203 | |
1183 | =back |
1204 | =back |
1184 | |
1205 | |
|
|
1206 | =head3 Examples |
|
|
1207 | |
1185 | Example: Create a timer that fires after 60 seconds. |
1208 | Example: Create a timer that fires after 60 seconds. |
1186 | |
1209 | |
1187 | static void |
1210 | static void |
1188 | one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
1211 | one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
1189 | { |
1212 | { |
… | |
… | |
1252 | In this configuration the watcher triggers an event at the wallclock time |
1275 | In this configuration the watcher triggers an event at the wallclock time |
1253 | C<at> and doesn't repeat. It will not adjust when a time jump occurs, |
1276 | C<at> and doesn't repeat. It will not adjust when a time jump occurs, |
1254 | that is, if it is to be run at January 1st 2011 then it will run when the |
1277 | that is, if it is to be run at January 1st 2011 then it will run when the |
1255 | system time reaches or surpasses this time. |
1278 | system time reaches or surpasses this time. |
1256 | |
1279 | |
1257 | =item * non-repeating interval timer (at = offset, interval > 0, reschedule_cb = 0) |
1280 | =item * repeating interval timer (at = offset, interval > 0, reschedule_cb = 0) |
1258 | |
1281 | |
1259 | In this mode the watcher will always be scheduled to time out at the next |
1282 | In this mode the watcher will always be scheduled to time out at the next |
1260 | C<at + N * interval> time (for some integer N, which can also be negative) |
1283 | C<at + N * interval> time (for some integer N, which can also be negative) |
1261 | and then repeat, regardless of any time jumps. |
1284 | and then repeat, regardless of any time jumps. |
1262 | |
1285 | |
… | |
… | |
1345 | |
1368 | |
1346 | When active, contains the absolute time that the watcher is supposed to |
1369 | When active, contains the absolute time that the watcher is supposed to |
1347 | trigger next. |
1370 | trigger next. |
1348 | |
1371 | |
1349 | =back |
1372 | =back |
|
|
1373 | |
|
|
1374 | =head3 Examples |
1350 | |
1375 | |
1351 | Example: Call a callback every hour, or, more precisely, whenever the |
1376 | Example: Call a callback every hour, or, more precisely, whenever the |
1352 | system clock is divisible by 3600. The callback invocation times have |
1377 | system clock is divisible by 3600. The callback invocation times have |
1353 | potentially a lot of jittering, but good long-term stability. |
1378 | potentially a lot of jittering, but good long-term stability. |
1354 | |
1379 | |
… | |
… | |
1411 | |
1436 | |
1412 | The signal the watcher watches out for. |
1437 | The signal the watcher watches out for. |
1413 | |
1438 | |
1414 | =back |
1439 | =back |
1415 | |
1440 | |
|
|
1441 | =head3 Examples |
|
|
1442 | |
|
|
1443 | Example: Try to exit cleanly on SIGINT and SIGTERM. |
|
|
1444 | |
|
|
1445 | static void |
|
|
1446 | sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) |
|
|
1447 | { |
|
|
1448 | ev_unloop (loop, EVUNLOOP_ALL); |
|
|
1449 | } |
|
|
1450 | |
|
|
1451 | struct ev_signal signal_watcher; |
|
|
1452 | ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
|
|
1453 | ev_signal_start (loop, &sigint_cb); |
|
|
1454 | |
1416 | |
1455 | |
1417 | =head2 C<ev_child> - watch out for process status changes |
1456 | =head2 C<ev_child> - watch out for process status changes |
1418 | |
1457 | |
1419 | Child watchers trigger when your process receives a SIGCHLD in response to |
1458 | Child watchers trigger when your process receives a SIGCHLD in response to |
1420 | some child status changes (most typically when a child of yours dies). |
1459 | some child status changes (most typically when a child of yours dies). It |
|
|
1460 | is permissible to install a child watcher I<after> the child has been |
|
|
1461 | forked (which implies it might have already exited), as long as the event |
|
|
1462 | loop isn't entered (or is continued from a watcher). |
|
|
1463 | |
|
|
1464 | Only the default event loop is capable of handling signals, and therefore |
|
|
1465 | you can only rgeister child watchers in the default event loop. |
|
|
1466 | |
|
|
1467 | =head3 Process Interaction |
|
|
1468 | |
|
|
1469 | Libev grabs C<SIGCHLD> as soon as the default event loop is |
|
|
1470 | initialised. This is necessary to guarantee proper behaviour even if |
|
|
1471 | the first child watcher is started after the child exits. The occurance |
|
|
1472 | of C<SIGCHLD> is recorded asynchronously, but child reaping is done |
|
|
1473 | synchronously as part of the event loop processing. Libev always reaps all |
|
|
1474 | children, even ones not watched. |
|
|
1475 | |
|
|
1476 | =head3 Overriding the Built-In Processing |
|
|
1477 | |
|
|
1478 | Libev offers no special support for overriding the built-in child |
|
|
1479 | processing, but if your application collides with libev's default child |
|
|
1480 | handler, you can override it easily by installing your own handler for |
|
|
1481 | C<SIGCHLD> after initialising the default loop, and making sure the |
|
|
1482 | default loop never gets destroyed. You are encouraged, however, to use an |
|
|
1483 | event-based approach to child reaping and thus use libev's support for |
|
|
1484 | that, so other libev users can use C<ev_child> watchers freely. |
1421 | |
1485 | |
1422 | =head3 Watcher-Specific Functions and Data Members |
1486 | =head3 Watcher-Specific Functions and Data Members |
1423 | |
1487 | |
1424 | =over 4 |
1488 | =over 4 |
1425 | |
1489 | |
1426 | =item ev_child_init (ev_child *, callback, int pid) |
1490 | =item ev_child_init (ev_child *, callback, int pid, int trace) |
1427 | |
1491 | |
1428 | =item ev_child_set (ev_child *, int pid) |
1492 | =item ev_child_set (ev_child *, int pid, int trace) |
1429 | |
1493 | |
1430 | Configures the watcher to wait for status changes of process C<pid> (or |
1494 | Configures the watcher to wait for status changes of process C<pid> (or |
1431 | I<any> process if C<pid> is specified as C<0>). The callback can look |
1495 | I<any> process if C<pid> is specified as C<0>). The callback can look |
1432 | at the C<rstatus> member of the C<ev_child> watcher structure to see |
1496 | at the C<rstatus> member of the C<ev_child> watcher structure to see |
1433 | the status word (use the macros from C<sys/wait.h> and see your systems |
1497 | the status word (use the macros from C<sys/wait.h> and see your systems |
1434 | C<waitpid> documentation). The C<rpid> member contains the pid of the |
1498 | C<waitpid> documentation). The C<rpid> member contains the pid of the |
1435 | process causing the status change. |
1499 | process causing the status change. C<trace> must be either C<0> (only |
|
|
1500 | activate the watcher when the process terminates) or C<1> (additionally |
|
|
1501 | activate the watcher when the process is stopped or continued). |
1436 | |
1502 | |
1437 | =item int pid [read-only] |
1503 | =item int pid [read-only] |
1438 | |
1504 | |
1439 | The process id this watcher watches out for, or C<0>, meaning any process id. |
1505 | The process id this watcher watches out for, or C<0>, meaning any process id. |
1440 | |
1506 | |
… | |
… | |
1447 | The process exit/trace status caused by C<rpid> (see your systems |
1513 | The process exit/trace status caused by C<rpid> (see your systems |
1448 | C<waitpid> and C<sys/wait.h> documentation for details). |
1514 | C<waitpid> and C<sys/wait.h> documentation for details). |
1449 | |
1515 | |
1450 | =back |
1516 | =back |
1451 | |
1517 | |
1452 | Example: Try to exit cleanly on SIGINT and SIGTERM. |
1518 | =head3 Examples |
|
|
1519 | |
|
|
1520 | Example: C<fork()> a new process and install a child handler to wait for |
|
|
1521 | its completion. |
|
|
1522 | |
|
|
1523 | ev_child cw; |
1453 | |
1524 | |
1454 | static void |
1525 | static void |
1455 | sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) |
1526 | child_cb (EV_P_ struct ev_child *w, int revents) |
1456 | { |
1527 | { |
1457 | ev_unloop (loop, EVUNLOOP_ALL); |
1528 | ev_child_stop (EV_A_ w); |
|
|
1529 | printf ("process %d exited with status %x\n", w->rpid, w->rstatus); |
1458 | } |
1530 | } |
1459 | |
1531 | |
1460 | struct ev_signal signal_watcher; |
1532 | pid_t pid = fork (); |
1461 | ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
1533 | |
1462 | ev_signal_start (loop, &sigint_cb); |
1534 | if (pid < 0) |
|
|
1535 | // error |
|
|
1536 | else if (pid == 0) |
|
|
1537 | { |
|
|
1538 | // the forked child executes here |
|
|
1539 | exit (1); |
|
|
1540 | } |
|
|
1541 | else |
|
|
1542 | { |
|
|
1543 | ev_child_init (&cw, child_cb, pid, 0); |
|
|
1544 | ev_child_start (EV_DEFAULT_ &cw); |
|
|
1545 | } |
1463 | |
1546 | |
1464 | |
1547 | |
1465 | =head2 C<ev_stat> - did the file attributes just change? |
1548 | =head2 C<ev_stat> - did the file attributes just change? |
1466 | |
1549 | |
1467 | This watches a filesystem path for attribute changes. That is, it calls |
1550 | This watches a filesystem path for attribute changes. That is, it calls |
… | |
… | |
1496 | semantics of C<ev_stat> watchers, which means that libev sometimes needs |
1579 | semantics of C<ev_stat> watchers, which means that libev sometimes needs |
1497 | to fall back to regular polling again even with inotify, but changes are |
1580 | to fall back to regular polling again even with inotify, but changes are |
1498 | usually detected immediately, and if the file exists there will be no |
1581 | usually detected immediately, and if the file exists there will be no |
1499 | polling. |
1582 | polling. |
1500 | |
1583 | |
|
|
1584 | =head3 Inotify |
|
|
1585 | |
|
|
1586 | When C<inotify (7)> support has been compiled into libev (generally only |
|
|
1587 | available on Linux) and present at runtime, it will be used to speed up |
|
|
1588 | change detection where possible. The inotify descriptor will be created lazily |
|
|
1589 | when the first C<ev_stat> watcher is being started. |
|
|
1590 | |
|
|
1591 | Inotify presense does not change the semantics of C<ev_stat> watchers |
|
|
1592 | except that changes might be detected earlier, and in some cases, to avoid |
|
|
1593 | making regular C<stat> calls. Even in the presense of inotify support |
|
|
1594 | there are many cases where libev has to resort to regular C<stat> polling. |
|
|
1595 | |
|
|
1596 | (There is no support for kqueue, as apparently it cannot be used to |
|
|
1597 | implement this functionality, due to the requirement of having a file |
|
|
1598 | descriptor open on the object at all times). |
|
|
1599 | |
|
|
1600 | =head3 The special problem of stat time resolution |
|
|
1601 | |
|
|
1602 | The C<stat ()> syscall only supports full-second resolution portably, and |
|
|
1603 | even on systems where the resolution is higher, many filesystems still |
|
|
1604 | only support whole seconds. |
|
|
1605 | |
|
|
1606 | That means that, if the time is the only thing that changes, you might |
|
|
1607 | miss updates: on the first update, C<ev_stat> detects a change and calls |
|
|
1608 | your callback, which does something. When there is another update within |
|
|
1609 | the same second, C<ev_stat> will be unable to detect it. |
|
|
1610 | |
|
|
1611 | The solution to this is to delay acting on a change for a second (or till |
|
|
1612 | the next second boundary), using a roughly one-second delay C<ev_timer> |
|
|
1613 | (C<ev_timer_set (w, 0., 1.01); ev_timer_again (loop, w)>). The C<.01> |
|
|
1614 | is added to work around small timing inconsistencies of some operating |
|
|
1615 | systems. |
|
|
1616 | |
1501 | =head3 Watcher-Specific Functions and Data Members |
1617 | =head3 Watcher-Specific Functions and Data Members |
1502 | |
1618 | |
1503 | =over 4 |
1619 | =over 4 |
1504 | |
1620 | |
1505 | =item ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval) |
1621 | =item ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval) |
… | |
… | |
1514 | |
1630 | |
1515 | The callback will be receive C<EV_STAT> when a change was detected, |
1631 | The callback will be receive C<EV_STAT> when a change was detected, |
1516 | relative to the attributes at the time the watcher was started (or the |
1632 | relative to the attributes at the time the watcher was started (or the |
1517 | last change was detected). |
1633 | last change was detected). |
1518 | |
1634 | |
1519 | =item ev_stat_stat (ev_stat *) |
1635 | =item ev_stat_stat (loop, ev_stat *) |
1520 | |
1636 | |
1521 | Updates the stat buffer immediately with new values. If you change the |
1637 | Updates the stat buffer immediately with new values. If you change the |
1522 | watched path in your callback, you could call this fucntion to avoid |
1638 | watched path in your callback, you could call this fucntion to avoid |
1523 | detecting this change (while introducing a race condition). Can also be |
1639 | detecting this change (while introducing a race condition). Can also be |
1524 | useful simply to find out the new values. |
1640 | useful simply to find out the new values. |
… | |
… | |
1542 | =item const char *path [read-only] |
1658 | =item const char *path [read-only] |
1543 | |
1659 | |
1544 | The filesystem path that is being watched. |
1660 | The filesystem path that is being watched. |
1545 | |
1661 | |
1546 | =back |
1662 | =back |
|
|
1663 | |
|
|
1664 | =head3 Examples |
1547 | |
1665 | |
1548 | Example: Watch C</etc/passwd> for attribute changes. |
1666 | Example: Watch C</etc/passwd> for attribute changes. |
1549 | |
1667 | |
1550 | static void |
1668 | static void |
1551 | passwd_cb (struct ev_loop *loop, ev_stat *w, int revents) |
1669 | passwd_cb (struct ev_loop *loop, ev_stat *w, int revents) |
… | |
… | |
1564 | } |
1682 | } |
1565 | |
1683 | |
1566 | ... |
1684 | ... |
1567 | ev_stat passwd; |
1685 | ev_stat passwd; |
1568 | |
1686 | |
1569 | ev_stat_init (&passwd, passwd_cb, "/etc/passwd"); |
1687 | ev_stat_init (&passwd, passwd_cb, "/etc/passwd", 0.); |
1570 | ev_stat_start (loop, &passwd); |
1688 | ev_stat_start (loop, &passwd); |
|
|
1689 | |
|
|
1690 | Example: Like above, but additionally use a one-second delay so we do not |
|
|
1691 | miss updates (however, frequent updates will delay processing, too, so |
|
|
1692 | one might do the work both on C<ev_stat> callback invocation I<and> on |
|
|
1693 | C<ev_timer> callback invocation). |
|
|
1694 | |
|
|
1695 | static ev_stat passwd; |
|
|
1696 | static ev_timer timer; |
|
|
1697 | |
|
|
1698 | static void |
|
|
1699 | timer_cb (EV_P_ ev_timer *w, int revents) |
|
|
1700 | { |
|
|
1701 | ev_timer_stop (EV_A_ w); |
|
|
1702 | |
|
|
1703 | /* now it's one second after the most recent passwd change */ |
|
|
1704 | } |
|
|
1705 | |
|
|
1706 | static void |
|
|
1707 | stat_cb (EV_P_ ev_stat *w, int revents) |
|
|
1708 | { |
|
|
1709 | /* reset the one-second timer */ |
|
|
1710 | ev_timer_again (EV_A_ &timer); |
|
|
1711 | } |
|
|
1712 | |
|
|
1713 | ... |
|
|
1714 | ev_stat_init (&passwd, stat_cb, "/etc/passwd", 0.); |
|
|
1715 | ev_stat_start (loop, &passwd); |
|
|
1716 | ev_timer_init (&timer, timer_cb, 0., 1.01); |
1571 | |
1717 | |
1572 | |
1718 | |
1573 | =head2 C<ev_idle> - when you've got nothing better to do... |
1719 | =head2 C<ev_idle> - when you've got nothing better to do... |
1574 | |
1720 | |
1575 | Idle watchers trigger events when no other events of the same or higher |
1721 | Idle watchers trigger events when no other events of the same or higher |
… | |
… | |
1601 | kind. There is a C<ev_idle_set> macro, but using it is utterly pointless, |
1747 | kind. There is a C<ev_idle_set> macro, but using it is utterly pointless, |
1602 | believe me. |
1748 | believe me. |
1603 | |
1749 | |
1604 | =back |
1750 | =back |
1605 | |
1751 | |
|
|
1752 | =head3 Examples |
|
|
1753 | |
1606 | Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the |
1754 | Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the |
1607 | callback, free it. Also, use no error checking, as usual. |
1755 | callback, free it. Also, use no error checking, as usual. |
1608 | |
1756 | |
1609 | static void |
1757 | static void |
1610 | idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents) |
1758 | idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents) |
1611 | { |
1759 | { |
1612 | free (w); |
1760 | free (w); |
1613 | // now do something you wanted to do when the program has |
1761 | // now do something you wanted to do when the program has |
1614 | // no longer asnything immediate to do. |
1762 | // no longer anything immediate to do. |
1615 | } |
1763 | } |
1616 | |
1764 | |
1617 | struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle)); |
1765 | struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle)); |
1618 | ev_idle_init (idle_watcher, idle_cb); |
1766 | ev_idle_init (idle_watcher, idle_cb); |
1619 | ev_idle_start (loop, idle_cb); |
1767 | ev_idle_start (loop, idle_cb); |
… | |
… | |
1681 | parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set> |
1829 | parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set> |
1682 | macros, but using them is utterly, utterly and completely pointless. |
1830 | macros, but using them is utterly, utterly and completely pointless. |
1683 | |
1831 | |
1684 | =back |
1832 | =back |
1685 | |
1833 | |
|
|
1834 | =head3 Examples |
|
|
1835 | |
1686 | There are a number of principal ways to embed other event loops or modules |
1836 | There are a number of principal ways to embed other event loops or modules |
1687 | into libev. Here are some ideas on how to include libadns into libev |
1837 | into libev. Here are some ideas on how to include libadns into libev |
1688 | (there is a Perl module named C<EV::ADNS> that does this, which you could |
1838 | (there is a Perl module named C<EV::ADNS> that does this, which you could |
1689 | use for an actually working example. Another Perl module named C<EV::Glib> |
1839 | use for an actually working example. Another Perl module named C<EV::Glib> |
1690 | embeds a Glib main context into libev, and finally, C<Glib::EV> embeds EV |
1840 | embeds a Glib main context into libev, and finally, C<Glib::EV> embeds EV |
… | |
… | |
1858 | portable one. |
2008 | portable one. |
1859 | |
2009 | |
1860 | So when you want to use this feature you will always have to be prepared |
2010 | So when you want to use this feature you will always have to be prepared |
1861 | that you cannot get an embeddable loop. The recommended way to get around |
2011 | that you cannot get an embeddable loop. The recommended way to get around |
1862 | this is to have a separate variables for your embeddable loop, try to |
2012 | this is to have a separate variables for your embeddable loop, try to |
1863 | create it, and if that fails, use the normal loop for everything: |
2013 | create it, and if that fails, use the normal loop for everything. |
|
|
2014 | |
|
|
2015 | =head3 Watcher-Specific Functions and Data Members |
|
|
2016 | |
|
|
2017 | =over 4 |
|
|
2018 | |
|
|
2019 | =item ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop) |
|
|
2020 | |
|
|
2021 | =item ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop) |
|
|
2022 | |
|
|
2023 | Configures the watcher to embed the given loop, which must be |
|
|
2024 | embeddable. If the callback is C<0>, then C<ev_embed_sweep> will be |
|
|
2025 | invoked automatically, otherwise it is the responsibility of the callback |
|
|
2026 | to invoke it (it will continue to be called until the sweep has been done, |
|
|
2027 | if you do not want thta, you need to temporarily stop the embed watcher). |
|
|
2028 | |
|
|
2029 | =item ev_embed_sweep (loop, ev_embed *) |
|
|
2030 | |
|
|
2031 | Make a single, non-blocking sweep over the embedded loop. This works |
|
|
2032 | similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most |
|
|
2033 | apropriate way for embedded loops. |
|
|
2034 | |
|
|
2035 | =item struct ev_loop *other [read-only] |
|
|
2036 | |
|
|
2037 | The embedded event loop. |
|
|
2038 | |
|
|
2039 | =back |
|
|
2040 | |
|
|
2041 | =head3 Examples |
|
|
2042 | |
|
|
2043 | Example: Try to get an embeddable event loop and embed it into the default |
|
|
2044 | event loop. If that is not possible, use the default loop. The default |
|
|
2045 | loop is stored in C<loop_hi>, while the mebeddable loop is stored in |
|
|
2046 | C<loop_lo> (which is C<loop_hi> in the acse no embeddable loop can be |
|
|
2047 | used). |
1864 | |
2048 | |
1865 | struct ev_loop *loop_hi = ev_default_init (0); |
2049 | struct ev_loop *loop_hi = ev_default_init (0); |
1866 | struct ev_loop *loop_lo = 0; |
2050 | struct ev_loop *loop_lo = 0; |
1867 | struct ev_embed embed; |
2051 | struct ev_embed embed; |
1868 | |
2052 | |
… | |
… | |
1879 | ev_embed_start (loop_hi, &embed); |
2063 | ev_embed_start (loop_hi, &embed); |
1880 | } |
2064 | } |
1881 | else |
2065 | else |
1882 | loop_lo = loop_hi; |
2066 | loop_lo = loop_hi; |
1883 | |
2067 | |
1884 | =head3 Watcher-Specific Functions and Data Members |
2068 | Example: Check if kqueue is available but not recommended and create |
|
|
2069 | a kqueue backend for use with sockets (which usually work with any |
|
|
2070 | kqueue implementation). Store the kqueue/socket-only event loop in |
|
|
2071 | C<loop_socket>. (One might optionally use C<EVFLAG_NOENV>, too). |
1885 | |
2072 | |
1886 | =over 4 |
2073 | struct ev_loop *loop = ev_default_init (0); |
|
|
2074 | struct ev_loop *loop_socket = 0; |
|
|
2075 | struct ev_embed embed; |
|
|
2076 | |
|
|
2077 | if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE) |
|
|
2078 | if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE)) |
|
|
2079 | { |
|
|
2080 | ev_embed_init (&embed, 0, loop_socket); |
|
|
2081 | ev_embed_start (loop, &embed); |
|
|
2082 | } |
1887 | |
2083 | |
1888 | =item ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop) |
2084 | if (!loop_socket) |
|
|
2085 | loop_socket = loop; |
1889 | |
2086 | |
1890 | =item ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop) |
2087 | // now use loop_socket for all sockets, and loop for everything else |
1891 | |
|
|
1892 | Configures the watcher to embed the given loop, which must be |
|
|
1893 | embeddable. If the callback is C<0>, then C<ev_embed_sweep> will be |
|
|
1894 | invoked automatically, otherwise it is the responsibility of the callback |
|
|
1895 | to invoke it (it will continue to be called until the sweep has been done, |
|
|
1896 | if you do not want thta, you need to temporarily stop the embed watcher). |
|
|
1897 | |
|
|
1898 | =item ev_embed_sweep (loop, ev_embed *) |
|
|
1899 | |
|
|
1900 | Make a single, non-blocking sweep over the embedded loop. This works |
|
|
1901 | similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most |
|
|
1902 | apropriate way for embedded loops. |
|
|
1903 | |
|
|
1904 | =item struct ev_loop *other [read-only] |
|
|
1905 | |
|
|
1906 | The embedded event loop. |
|
|
1907 | |
|
|
1908 | =back |
|
|
1909 | |
2088 | |
1910 | |
2089 | |
1911 | =head2 C<ev_fork> - the audacity to resume the event loop after a fork |
2090 | =head2 C<ev_fork> - the audacity to resume the event loop after a fork |
1912 | |
2091 | |
1913 | Fork watchers are called when a C<fork ()> was detected (usually because |
2092 | Fork watchers are called when a C<fork ()> was detected (usually because |
… | |
… | |
1929 | believe me. |
2108 | believe me. |
1930 | |
2109 | |
1931 | =back |
2110 | =back |
1932 | |
2111 | |
1933 | |
2112 | |
|
|
2113 | =head2 C<ev_async> - how to wake up another event loop |
|
|
2114 | |
|
|
2115 | In general, you cannot use an C<ev_loop> from multiple threads or other |
|
|
2116 | asynchronous sources such as signal handlers (as opposed to multiple event |
|
|
2117 | loops - those are of course safe to use in different threads). |
|
|
2118 | |
|
|
2119 | Sometimes, however, you need to wake up another event loop you do not |
|
|
2120 | control, for example because it belongs to another thread. This is what |
|
|
2121 | C<ev_async> watchers do: as long as the C<ev_async> watcher is active, you |
|
|
2122 | can signal it by calling C<ev_async_send>, which is thread- and signal |
|
|
2123 | safe. |
|
|
2124 | |
|
|
2125 | This functionality is very similar to C<ev_signal> watchers, as signals, |
|
|
2126 | too, are asynchronous in nature, and signals, too, will be compressed |
|
|
2127 | (i.e. the number of callback invocations may be less than the number of |
|
|
2128 | C<ev_async_sent> calls). |
|
|
2129 | |
|
|
2130 | Unlike C<ev_signal> watchers, C<ev_async> works with any event loop, not |
|
|
2131 | just the default loop. |
|
|
2132 | |
|
|
2133 | =head3 Queueing |
|
|
2134 | |
|
|
2135 | C<ev_async> does not support queueing of data in any way. The reason |
|
|
2136 | is that the author does not know of a simple (or any) algorithm for a |
|
|
2137 | multiple-writer-single-reader queue that works in all cases and doesn't |
|
|
2138 | need elaborate support such as pthreads. |
|
|
2139 | |
|
|
2140 | That means that if you want to queue data, you have to provide your own |
|
|
2141 | queue. But at least I can tell you would implement locking around your |
|
|
2142 | queue: |
|
|
2143 | |
|
|
2144 | =over 4 |
|
|
2145 | |
|
|
2146 | =item queueing from a signal handler context |
|
|
2147 | |
|
|
2148 | To implement race-free queueing, you simply add to the queue in the signal |
|
|
2149 | handler but you block the signal handler in the watcher callback. Here is an example that does that for |
|
|
2150 | some fictitiuous SIGUSR1 handler: |
|
|
2151 | |
|
|
2152 | static ev_async mysig; |
|
|
2153 | |
|
|
2154 | static void |
|
|
2155 | sigusr1_handler (void) |
|
|
2156 | { |
|
|
2157 | sometype data; |
|
|
2158 | |
|
|
2159 | // no locking etc. |
|
|
2160 | queue_put (data); |
|
|
2161 | ev_async_send (EV_DEFAULT_ &mysig); |
|
|
2162 | } |
|
|
2163 | |
|
|
2164 | static void |
|
|
2165 | mysig_cb (EV_P_ ev_async *w, int revents) |
|
|
2166 | { |
|
|
2167 | sometype data; |
|
|
2168 | sigset_t block, prev; |
|
|
2169 | |
|
|
2170 | sigemptyset (&block); |
|
|
2171 | sigaddset (&block, SIGUSR1); |
|
|
2172 | sigprocmask (SIG_BLOCK, &block, &prev); |
|
|
2173 | |
|
|
2174 | while (queue_get (&data)) |
|
|
2175 | process (data); |
|
|
2176 | |
|
|
2177 | if (sigismember (&prev, SIGUSR1) |
|
|
2178 | sigprocmask (SIG_UNBLOCK, &block, 0); |
|
|
2179 | } |
|
|
2180 | |
|
|
2181 | (Note: pthreads in theory requires you to use C<pthread_setmask> |
|
|
2182 | instead of C<sigprocmask> when you use threads, but libev doesn't do it |
|
|
2183 | either...). |
|
|
2184 | |
|
|
2185 | =item queueing from a thread context |
|
|
2186 | |
|
|
2187 | The strategy for threads is different, as you cannot (easily) block |
|
|
2188 | threads but you can easily preempt them, so to queue safely you need to |
|
|
2189 | employ a traditional mutex lock, such as in this pthread example: |
|
|
2190 | |
|
|
2191 | static ev_async mysig; |
|
|
2192 | static pthread_mutex_t mymutex = PTHREAD_MUTEX_INITIALIZER; |
|
|
2193 | |
|
|
2194 | static void |
|
|
2195 | otherthread (void) |
|
|
2196 | { |
|
|
2197 | // only need to lock the actual queueing operation |
|
|
2198 | pthread_mutex_lock (&mymutex); |
|
|
2199 | queue_put (data); |
|
|
2200 | pthread_mutex_unlock (&mymutex); |
|
|
2201 | |
|
|
2202 | ev_async_send (EV_DEFAULT_ &mysig); |
|
|
2203 | } |
|
|
2204 | |
|
|
2205 | static void |
|
|
2206 | mysig_cb (EV_P_ ev_async *w, int revents) |
|
|
2207 | { |
|
|
2208 | pthread_mutex_lock (&mymutex); |
|
|
2209 | |
|
|
2210 | while (queue_get (&data)) |
|
|
2211 | process (data); |
|
|
2212 | |
|
|
2213 | pthread_mutex_unlock (&mymutex); |
|
|
2214 | } |
|
|
2215 | |
|
|
2216 | =back |
|
|
2217 | |
|
|
2218 | |
|
|
2219 | =head3 Watcher-Specific Functions and Data Members |
|
|
2220 | |
|
|
2221 | =over 4 |
|
|
2222 | |
|
|
2223 | =item ev_async_init (ev_async *, callback) |
|
|
2224 | |
|
|
2225 | Initialises and configures the async watcher - it has no parameters of any |
|
|
2226 | kind. There is a C<ev_asynd_set> macro, but using it is utterly pointless, |
|
|
2227 | believe me. |
|
|
2228 | |
|
|
2229 | =item ev_async_send (loop, ev_async *) |
|
|
2230 | |
|
|
2231 | Sends/signals/activates the given C<ev_async> watcher, that is, feeds |
|
|
2232 | an C<EV_ASYNC> event on the watcher into the event loop. Unlike |
|
|
2233 | C<ev_feed_event>, this call is safe to do in other threads, signal or |
|
|
2234 | similar contexts (see the dicusssion of C<EV_ATOMIC_T> in the embedding |
|
|
2235 | section below on what exactly this means). |
|
|
2236 | |
|
|
2237 | This call incurs the overhead of a syscall only once per loop iteration, |
|
|
2238 | so while the overhead might be noticable, it doesn't apply to repeated |
|
|
2239 | calls to C<ev_async_send>. |
|
|
2240 | |
|
|
2241 | =back |
|
|
2242 | |
|
|
2243 | |
1934 | =head1 OTHER FUNCTIONS |
2244 | =head1 OTHER FUNCTIONS |
1935 | |
2245 | |
1936 | There are some other functions of possible interest. Described. Here. Now. |
2246 | There are some other functions of possible interest. Described. Here. Now. |
1937 | |
2247 | |
1938 | =over 4 |
2248 | =over 4 |
… | |
… | |
2165 | Example: Define a class with an IO and idle watcher, start one of them in |
2475 | Example: Define a class with an IO and idle watcher, start one of them in |
2166 | the constructor. |
2476 | the constructor. |
2167 | |
2477 | |
2168 | class myclass |
2478 | class myclass |
2169 | { |
2479 | { |
2170 | ev_io io; void io_cb (ev::io &w, int revents); |
2480 | ev::io io; void io_cb (ev::io &w, int revents); |
2171 | ev_idle idle void idle_cb (ev::idle &w, int revents); |
2481 | ev:idle idle void idle_cb (ev::idle &w, int revents); |
2172 | |
2482 | |
2173 | myclass (); |
2483 | myclass (int fd) |
2174 | } |
|
|
2175 | |
|
|
2176 | myclass::myclass (int fd) |
|
|
2177 | { |
2484 | { |
2178 | io .set <myclass, &myclass::io_cb > (this); |
2485 | io .set <myclass, &myclass::io_cb > (this); |
2179 | idle.set <myclass, &myclass::idle_cb> (this); |
2486 | idle.set <myclass, &myclass::idle_cb> (this); |
2180 | |
2487 | |
2181 | io.start (fd, ev::READ); |
2488 | io.start (fd, ev::READ); |
|
|
2489 | } |
2182 | } |
2490 | }; |
2183 | |
2491 | |
2184 | |
2492 | |
2185 | =head1 MACRO MAGIC |
2493 | =head1 MACRO MAGIC |
2186 | |
2494 | |
2187 | Libev can be compiled with a variety of options, the most fundamantal |
2495 | Libev can be compiled with a variety of options, the most fundamantal |
… | |
… | |
2392 | wants osf handles on win32 (this is the case when the select to |
2700 | wants osf handles on win32 (this is the case when the select to |
2393 | be used is the winsock select). This means that it will call |
2701 | be used is the winsock select). This means that it will call |
2394 | C<_get_osfhandle> on the fd to convert it to an OS handle. Otherwise, |
2702 | C<_get_osfhandle> on the fd to convert it to an OS handle. Otherwise, |
2395 | it is assumed that all these functions actually work on fds, even |
2703 | it is assumed that all these functions actually work on fds, even |
2396 | on win32. Should not be defined on non-win32 platforms. |
2704 | on win32. Should not be defined on non-win32 platforms. |
|
|
2705 | |
|
|
2706 | =item EV_FD_TO_WIN32_HANDLE |
|
|
2707 | |
|
|
2708 | If C<EV_SELECT_IS_WINSOCKET> is enabled, then libev needs a way to map |
|
|
2709 | file descriptors to socket handles. When not defining this symbol (the |
|
|
2710 | default), then libev will call C<_get_osfhandle>, which is usually |
|
|
2711 | correct. In some cases, programs use their own file descriptor management, |
|
|
2712 | in which case they can provide this function to map fds to socket handles. |
2397 | |
2713 | |
2398 | =item EV_USE_POLL |
2714 | =item EV_USE_POLL |
2399 | |
2715 | |
2400 | If defined to be C<1>, libev will compile in support for the C<poll>(2) |
2716 | If defined to be C<1>, libev will compile in support for the C<poll>(2) |
2401 | backend. Otherwise it will be enabled on non-win32 platforms. It |
2717 | backend. Otherwise it will be enabled on non-win32 platforms. It |
… | |
… | |
2435 | |
2751 | |
2436 | If defined to be C<1>, libev will compile in support for the Linux inotify |
2752 | If defined to be C<1>, libev will compile in support for the Linux inotify |
2437 | interface to speed up C<ev_stat> watchers. Its actual availability will |
2753 | interface to speed up C<ev_stat> watchers. Its actual availability will |
2438 | be detected at runtime. |
2754 | be detected at runtime. |
2439 | |
2755 | |
|
|
2756 | =item EV_ATOMIC_T |
|
|
2757 | |
|
|
2758 | Libev requires an integer type (suitable for storing C<0> or C<1>) whose |
|
|
2759 | access is atomic with respect to other threads or signal contexts. No such |
|
|
2760 | type is easily found in the C language, so you can provide your own type |
|
|
2761 | that you know is safe for your purposes. It is used both for signal handler "locking" |
|
|
2762 | as well as for signal and thread safety in C<ev_async> watchers. |
|
|
2763 | |
|
|
2764 | In the absense of this define, libev will use C<sig_atomic_t volatile> |
|
|
2765 | (from F<signal.h>), which is usually good enough on most platforms. |
|
|
2766 | |
2440 | =item EV_H |
2767 | =item EV_H |
2441 | |
2768 | |
2442 | The name of the F<ev.h> header file used to include it. The default if |
2769 | The name of the F<ev.h> header file used to include it. The default if |
2443 | undefined is C<< <ev.h> >> in F<event.h> and C<"ev.h"> in F<ev.c>. This |
2770 | undefined is C<"ev.h"> in F<event.h>, F<ev.c> and F<ev++.h>. This can be |
2444 | can be used to virtually rename the F<ev.h> header file in case of conflicts. |
2771 | used to virtually rename the F<ev.h> header file in case of conflicts. |
2445 | |
2772 | |
2446 | =item EV_CONFIG_H |
2773 | =item EV_CONFIG_H |
2447 | |
2774 | |
2448 | If C<EV_STANDALONE> isn't C<1>, this variable can be used to override |
2775 | If C<EV_STANDALONE> isn't C<1>, this variable can be used to override |
2449 | F<ev.c>'s idea of where to find the F<config.h> file, similarly to |
2776 | F<ev.c>'s idea of where to find the F<config.h> file, similarly to |
2450 | C<EV_H>, above. |
2777 | C<EV_H>, above. |
2451 | |
2778 | |
2452 | =item EV_EVENT_H |
2779 | =item EV_EVENT_H |
2453 | |
2780 | |
2454 | Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea |
2781 | Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea |
2455 | of how the F<event.h> header can be found. |
2782 | of how the F<event.h> header can be found, the default is C<"event.h">. |
2456 | |
2783 | |
2457 | =item EV_PROTOTYPES |
2784 | =item EV_PROTOTYPES |
2458 | |
2785 | |
2459 | If defined to be C<0>, then F<ev.h> will not define any function |
2786 | If defined to be C<0>, then F<ev.h> will not define any function |
2460 | prototypes, but still define all the structs and other symbols. This is |
2787 | prototypes, but still define all the structs and other symbols. This is |
… | |
… | |
2511 | =item EV_FORK_ENABLE |
2838 | =item EV_FORK_ENABLE |
2512 | |
2839 | |
2513 | If undefined or defined to be C<1>, then fork watchers are supported. If |
2840 | If undefined or defined to be C<1>, then fork watchers are supported. If |
2514 | defined to be C<0>, then they are not. |
2841 | defined to be C<0>, then they are not. |
2515 | |
2842 | |
|
|
2843 | =item EV_ASYNC_ENABLE |
|
|
2844 | |
|
|
2845 | If undefined or defined to be C<1>, then async watchers are supported. If |
|
|
2846 | defined to be C<0>, then they are not. |
|
|
2847 | |
2516 | =item EV_MINIMAL |
2848 | =item EV_MINIMAL |
2517 | |
2849 | |
2518 | If you need to shave off some kilobytes of code at the expense of some |
2850 | If you need to shave off some kilobytes of code at the expense of some |
2519 | speed, define this symbol to C<1>. Currently only used for gcc to override |
2851 | speed, define this symbol to C<1>. Currently only used for gcc to override |
2520 | some inlining decisions, saves roughly 30% codesize of amd64. |
2852 | some inlining decisions, saves roughly 30% codesize of amd64. |
… | |
… | |
2526 | than enough. If you need to manage thousands of children you might want to |
2858 | than enough. If you need to manage thousands of children you might want to |
2527 | increase this value (I<must> be a power of two). |
2859 | increase this value (I<must> be a power of two). |
2528 | |
2860 | |
2529 | =item EV_INOTIFY_HASHSIZE |
2861 | =item EV_INOTIFY_HASHSIZE |
2530 | |
2862 | |
2531 | C<ev_staz> watchers use a small hash table to distribute workload by |
2863 | C<ev_stat> watchers use a small hash table to distribute workload by |
2532 | inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>), |
2864 | inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>), |
2533 | usually more than enough. If you need to manage thousands of C<ev_stat> |
2865 | usually more than enough. If you need to manage thousands of C<ev_stat> |
2534 | watchers you might want to increase this value (I<must> be a power of |
2866 | watchers you might want to increase this value (I<must> be a power of |
2535 | two). |
2867 | two). |
2536 | |
2868 | |
… | |
… | |
2632 | |
2964 | |
2633 | =item Starting and stopping timer/periodic watchers: O(log skipped_other_timers) |
2965 | =item Starting and stopping timer/periodic watchers: O(log skipped_other_timers) |
2634 | |
2966 | |
2635 | This means that, when you have a watcher that triggers in one hour and |
2967 | This means that, when you have a watcher that triggers in one hour and |
2636 | there are 100 watchers that would trigger before that then inserting will |
2968 | there are 100 watchers that would trigger before that then inserting will |
2637 | have to skip those 100 watchers. |
2969 | have to skip roughly seven (C<ld 100>) of these watchers. |
2638 | |
2970 | |
2639 | =item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers) |
2971 | =item Changing timer/periodic watchers (by autorepeat or calling again): O(log skipped_other_timers) |
2640 | |
2972 | |
2641 | That means that for changing a timer costs less than removing/adding them |
2973 | That means that changing a timer costs less than removing/adding them |
2642 | as only the relative motion in the event queue has to be paid for. |
2974 | as only the relative motion in the event queue has to be paid for. |
2643 | |
2975 | |
2644 | =item Starting io/check/prepare/idle/signal/child watchers: O(1) |
2976 | =item Starting io/check/prepare/idle/signal/child/fork/async watchers: O(1) |
2645 | |
2977 | |
2646 | These just add the watcher into an array or at the head of a list. |
2978 | These just add the watcher into an array or at the head of a list. |
|
|
2979 | |
2647 | =item Stopping check/prepare/idle watchers: O(1) |
2980 | =item Stopping check/prepare/idle/fork/async watchers: O(1) |
2648 | |
2981 | |
2649 | =item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE)) |
2982 | =item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE)) |
2650 | |
2983 | |
2651 | These watchers are stored in lists then need to be walked to find the |
2984 | These watchers are stored in lists then need to be walked to find the |
2652 | correct watcher to remove. The lists are usually short (you don't usually |
2985 | correct watcher to remove. The lists are usually short (you don't usually |
2653 | have many watchers waiting for the same fd or signal). |
2986 | have many watchers waiting for the same fd or signal). |
2654 | |
2987 | |
2655 | =item Finding the next timer per loop iteration: O(1) |
2988 | =item Finding the next timer in each loop iteration: O(1) |
|
|
2989 | |
|
|
2990 | By virtue of using a binary heap, the next timer is always found at the |
|
|
2991 | beginning of the storage array. |
2656 | |
2992 | |
2657 | =item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd) |
2993 | =item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd) |
2658 | |
2994 | |
2659 | A change means an I/O watcher gets started or stopped, which requires |
2995 | A change means an I/O watcher gets started or stopped, which requires |
2660 | libev to recalculate its status (and possibly tell the kernel). |
2996 | libev to recalculate its status (and possibly tell the kernel, depending |
|
|
2997 | on backend and wether C<ev_io_set> was used). |
2661 | |
2998 | |
2662 | =item Activating one watcher: O(1) |
2999 | =item Activating one watcher (putting it into the pending state): O(1) |
2663 | |
3000 | |
2664 | =item Priority handling: O(number_of_priorities) |
3001 | =item Priority handling: O(number_of_priorities) |
2665 | |
3002 | |
2666 | Priorities are implemented by allocating some space for each |
3003 | Priorities are implemented by allocating some space for each |
2667 | priority. When doing priority-based operations, libev usually has to |
3004 | priority. When doing priority-based operations, libev usually has to |
2668 | linearly search all the priorities. |
3005 | linearly search all the priorities, but starting/stopping and activating |
|
|
3006 | watchers becomes O(1) w.r.t. priority handling. |
|
|
3007 | |
|
|
3008 | =item Sending an ev_async: O(1) |
|
|
3009 | |
|
|
3010 | =item Processing ev_async_send: O(number_of_async_watchers) |
|
|
3011 | |
|
|
3012 | =item Processing signals: O(max_signal_number) |
|
|
3013 | |
|
|
3014 | Sending involves a syscall I<iff> there were no other C<ev_async_send> |
|
|
3015 | calls in the current loop iteration. Checking for async and signal events |
|
|
3016 | involves iterating over all running async watchers or all signal numbers. |
2669 | |
3017 | |
2670 | =back |
3018 | =back |
2671 | |
3019 | |
2672 | |
3020 | |
|
|
3021 | =head1 Win32 platform limitations and workarounds |
|
|
3022 | |
|
|
3023 | Win32 doesn't support any of the standards (e.g. POSIX) that libev |
|
|
3024 | requires, and its I/O model is fundamentally incompatible with the POSIX |
|
|
3025 | model. Libev still offers limited functionality on this platform in |
|
|
3026 | the form of the C<EVBACKEND_SELECT> backend, and only supports socket |
|
|
3027 | descriptors. This only applies when using Win32 natively, not when using |
|
|
3028 | e.g. cygwin. |
|
|
3029 | |
|
|
3030 | There is no supported compilation method available on windows except |
|
|
3031 | embedding it into other applications. |
|
|
3032 | |
|
|
3033 | Due to the many, low, and arbitrary limits on the win32 platform and the |
|
|
3034 | abysmal performance of winsockets, using a large number of sockets is not |
|
|
3035 | recommended (and not reasonable). If your program needs to use more than |
|
|
3036 | a hundred or so sockets, then likely it needs to use a totally different |
|
|
3037 | implementation for windows, as libev offers the POSIX model, which cannot |
|
|
3038 | be implemented efficiently on windows (microsoft monopoly games). |
|
|
3039 | |
|
|
3040 | =over 4 |
|
|
3041 | |
|
|
3042 | =item The winsocket select function |
|
|
3043 | |
|
|
3044 | The winsocket C<select> function doesn't follow POSIX in that it requires |
|
|
3045 | socket I<handles> and not socket I<file descriptors>. This makes select |
|
|
3046 | very inefficient, and also requires a mapping from file descriptors |
|
|
3047 | to socket handles. See the discussion of the C<EV_SELECT_USE_FD_SET>, |
|
|
3048 | C<EV_SELECT_IS_WINSOCKET> and C<EV_FD_TO_WIN32_HANDLE> preprocessor |
|
|
3049 | symbols for more info. |
|
|
3050 | |
|
|
3051 | The configuration for a "naked" win32 using the microsoft runtime |
|
|
3052 | libraries and raw winsocket select is: |
|
|
3053 | |
|
|
3054 | #define EV_USE_SELECT 1 |
|
|
3055 | #define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */ |
|
|
3056 | |
|
|
3057 | Note that winsockets handling of fd sets is O(n), so you can easily get a |
|
|
3058 | complexity in the O(n²) range when using win32. |
|
|
3059 | |
|
|
3060 | =item Limited number of file descriptors |
|
|
3061 | |
|
|
3062 | Windows has numerous arbitrary (and low) limits on things. Early versions |
|
|
3063 | of winsocket's select only supported waiting for a max. of C<64> handles |
|
|
3064 | (probably owning to the fact that all windows kernels can only wait for |
|
|
3065 | C<64> things at the same time internally; microsoft recommends spawning a |
|
|
3066 | chain of threads and wait for 63 handles and the previous thread in each). |
|
|
3067 | |
|
|
3068 | Newer versions support more handles, but you need to define C<FD_SETSIZE> |
|
|
3069 | to some high number (e.g. C<2048>) before compiling the winsocket select |
|
|
3070 | call (which might be in libev or elsewhere, for example, perl does its own |
|
|
3071 | select emulation on windows). |
|
|
3072 | |
|
|
3073 | Another limit is the number of file descriptors in the microsoft runtime |
|
|
3074 | libraries, which by default is C<64> (there must be a hidden I<64> fetish |
|
|
3075 | or something like this inside microsoft). You can increase this by calling |
|
|
3076 | C<_setmaxstdio>, which can increase this limit to C<2048> (another |
|
|
3077 | arbitrary limit), but is broken in many versions of the microsoft runtime |
|
|
3078 | libraries. |
|
|
3079 | |
|
|
3080 | This might get you to about C<512> or C<2048> sockets (depending on |
|
|
3081 | windows version and/or the phase of the moon). To get more, you need to |
|
|
3082 | wrap all I/O functions and provide your own fd management, but the cost of |
|
|
3083 | calling select (O(n²)) will likely make this unworkable. |
|
|
3084 | |
|
|
3085 | =back |
|
|
3086 | |
|
|
3087 | |
2673 | =head1 AUTHOR |
3088 | =head1 AUTHOR |
2674 | |
3089 | |
2675 | Marc Lehmann <libev@schmorp.de>. |
3090 | Marc Lehmann <libev@schmorp.de>. |
2676 | |
3091 | |