… | |
… | |
6 | |
6 | |
7 | #include <ev.h> |
7 | #include <ev.h> |
8 | |
8 | |
9 | =head2 EXAMPLE PROGRAM |
9 | =head2 EXAMPLE PROGRAM |
10 | |
10 | |
|
|
11 | // a single header file is required |
11 | #include <ev.h> |
12 | #include <ev.h> |
12 | |
13 | |
|
|
14 | // every watcher type has its own typedef'd struct |
|
|
15 | // with the name ev_<type> |
13 | ev_io stdin_watcher; |
16 | ev_io stdin_watcher; |
14 | ev_timer timeout_watcher; |
17 | ev_timer timeout_watcher; |
15 | |
18 | |
|
|
19 | // all watcher callbacks have a similar signature |
16 | /* called when data readable on stdin */ |
20 | // this callback is called when data is readable on stdin |
17 | static void |
21 | static void |
18 | stdin_cb (EV_P_ struct ev_io *w, int revents) |
22 | stdin_cb (EV_P_ struct ev_io *w, int revents) |
19 | { |
23 | { |
20 | /* puts ("stdin ready"); */ |
24 | puts ("stdin ready"); |
21 | ev_io_stop (EV_A_ w); /* just a syntax example */ |
25 | // for one-shot events, one must manually stop the watcher |
22 | ev_unloop (EV_A_ EVUNLOOP_ALL); /* leave all loop calls */ |
26 | // with its corresponding stop function. |
|
|
27 | ev_io_stop (EV_A_ w); |
|
|
28 | |
|
|
29 | // this causes all nested ev_loop's to stop iterating |
|
|
30 | ev_unloop (EV_A_ EVUNLOOP_ALL); |
23 | } |
31 | } |
24 | |
32 | |
|
|
33 | // another callback, this time for a time-out |
25 | static void |
34 | static void |
26 | timeout_cb (EV_P_ struct ev_timer *w, int revents) |
35 | timeout_cb (EV_P_ struct ev_timer *w, int revents) |
27 | { |
36 | { |
28 | /* puts ("timeout"); */ |
37 | puts ("timeout"); |
29 | ev_unloop (EV_A_ EVUNLOOP_ONE); /* leave one loop call */ |
38 | // this causes the innermost ev_loop to stop iterating |
|
|
39 | ev_unloop (EV_A_ EVUNLOOP_ONE); |
30 | } |
40 | } |
31 | |
41 | |
32 | int |
42 | int |
33 | main (void) |
43 | main (void) |
34 | { |
44 | { |
|
|
45 | // use the default event loop unless you have special needs |
35 | struct ev_loop *loop = ev_default_loop (0); |
46 | struct ev_loop *loop = ev_default_loop (0); |
36 | |
47 | |
37 | /* initialise an io watcher, then start it */ |
48 | // initialise an io watcher, then start it |
|
|
49 | // this one will watch for stdin to become readable |
38 | ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ); |
50 | ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ); |
39 | ev_io_start (loop, &stdin_watcher); |
51 | ev_io_start (loop, &stdin_watcher); |
40 | |
52 | |
|
|
53 | // initialise a timer watcher, then start it |
41 | /* simple non-repeating 5.5 second timeout */ |
54 | // simple non-repeating 5.5 second timeout |
42 | ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.); |
55 | ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.); |
43 | ev_timer_start (loop, &timeout_watcher); |
56 | ev_timer_start (loop, &timeout_watcher); |
44 | |
57 | |
45 | /* loop till timeout or data ready */ |
58 | // now wait for events to arrive |
46 | ev_loop (loop, 0); |
59 | ev_loop (loop, 0); |
47 | |
60 | |
|
|
61 | // unloop was called, so exit |
48 | return 0; |
62 | return 0; |
49 | } |
63 | } |
50 | |
64 | |
51 | =head1 DESCRIPTION |
65 | =head1 DESCRIPTION |
52 | |
66 | |
53 | The newest version of this document is also available as a html-formatted |
67 | The newest version of this document is also available as an html-formatted |
54 | web page you might find easier to navigate when reading it for the first |
68 | web page you might find easier to navigate when reading it for the first |
55 | time: L<http://cvs.schmorp.de/libev/ev.html>. |
69 | time: L<http://cvs.schmorp.de/libev/ev.html>. |
56 | |
70 | |
57 | Libev is an event loop: you register interest in certain events (such as a |
71 | Libev is an event loop: you register interest in certain events (such as a |
58 | file descriptor being readable or a timeout occurring), and it will manage |
72 | file descriptor being readable or a timeout occurring), and it will manage |
… | |
… | |
84 | L<benchmark|http://libev.schmorp.de/bench.html> comparing it to libevent |
98 | L<benchmark|http://libev.schmorp.de/bench.html> comparing it to libevent |
85 | for example). |
99 | for example). |
86 | |
100 | |
87 | =head2 CONVENTIONS |
101 | =head2 CONVENTIONS |
88 | |
102 | |
89 | Libev is very configurable. In this manual the default configuration will |
103 | Libev is very configurable. In this manual the default (and most common) |
90 | be described, which supports multiple event loops. For more info about |
104 | configuration will be described, which supports multiple event loops. For |
91 | various configuration options please have a look at B<EMBED> section in |
105 | more info about various configuration options please have a look at |
92 | this manual. If libev was configured without support for multiple event |
106 | B<EMBED> section in this manual. If libev was configured without support |
93 | loops, then all functions taking an initial argument of name C<loop> |
107 | for multiple event loops, then all functions taking an initial argument of |
94 | (which is always of type C<struct ev_loop *>) will not have this argument. |
108 | name C<loop> (which is always of type C<struct ev_loop *>) will not have |
|
|
109 | this argument. |
95 | |
110 | |
96 | =head2 TIME REPRESENTATION |
111 | =head2 TIME REPRESENTATION |
97 | |
112 | |
98 | Libev represents time as a single floating point number, representing the |
113 | Libev represents time as a single floating point number, representing the |
99 | (fractional) number of seconds since the (POSIX) epoch (somewhere near |
114 | (fractional) number of seconds since the (POSIX) epoch (somewhere near |
… | |
… | |
260 | flags. If that is troubling you, check C<ev_backend ()> afterwards). |
275 | flags. If that is troubling you, check C<ev_backend ()> afterwards). |
261 | |
276 | |
262 | If you don't know what event loop to use, use the one returned from this |
277 | If you don't know what event loop to use, use the one returned from this |
263 | function. |
278 | function. |
264 | |
279 | |
|
|
280 | The default loop is the only loop that can handle C<ev_signal> and |
|
|
281 | C<ev_child> watchers, and to do this, it always registers a handler |
|
|
282 | for C<SIGCHLD>. If this is a problem for your app you can either |
|
|
283 | create a dynamic loop with C<ev_loop_new> that doesn't do that, or you |
|
|
284 | can simply overwrite the C<SIGCHLD> signal handler I<after> calling |
|
|
285 | C<ev_default_init>. |
|
|
286 | |
265 | The flags argument can be used to specify special behaviour or specific |
287 | 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>). |
288 | backends to use, and is usually specified as C<0> (or C<EVFLAG_AUTO>). |
267 | |
289 | |
268 | The following flags are supported: |
290 | The following flags are supported: |
269 | |
291 | |
… | |
… | |
290 | enabling this flag. |
312 | enabling this flag. |
291 | |
313 | |
292 | This works by calling C<getpid ()> on every iteration of the loop, |
314 | This works by calling C<getpid ()> on every iteration of the loop, |
293 | and thus this might slow down your event loop if you do a lot of loop |
315 | and thus this might slow down your event loop if you do a lot of loop |
294 | iterations and little real work, but is usually not noticeable (on my |
316 | iterations and little real work, but is usually not noticeable (on my |
295 | Linux system for example, C<getpid> is actually a simple 5-insn sequence |
317 | GNU/Linux system for example, C<getpid> is actually a simple 5-insn sequence |
296 | without a syscall and thus I<very> fast, but my Linux system also has |
318 | without a syscall and thus I<very> fast, but my GNU/Linux system also has |
297 | C<pthread_atfork> which is even faster). |
319 | C<pthread_atfork> which is even faster). |
298 | |
320 | |
299 | The big advantage of this flag is that you can forget about fork (and |
321 | The big advantage of this flag is that you can forget about fork (and |
300 | forget about forgetting to tell libev about forking) when you use this |
322 | forget about forgetting to tell libev about forking) when you use this |
301 | flag. |
323 | flag. |
… | |
… | |
403 | While this backend scales well, it requires one system call per active |
425 | 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 |
426 | file descriptor per loop iteration. For small and medium numbers of file |
405 | descriptors a "slow" C<EVBACKEND_SELECT> or C<EVBACKEND_POLL> backend |
427 | descriptors a "slow" C<EVBACKEND_SELECT> or C<EVBACKEND_POLL> backend |
406 | might perform better. |
428 | might perform better. |
407 | |
429 | |
|
|
430 | On the positive side, ignoring the spurious readyness notifications, this |
|
|
431 | backend actually performed to specification in all tests and is fully |
|
|
432 | embeddable, which is a rare feat among the OS-specific backends. |
|
|
433 | |
408 | =item C<EVBACKEND_ALL> |
434 | =item C<EVBACKEND_ALL> |
409 | |
435 | |
410 | Try all backends (even potentially broken ones that wouldn't be tried |
436 | 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 |
437 | with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as |
412 | C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>. |
438 | C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>. |
… | |
… | |
414 | It is definitely not recommended to use this flag. |
440 | It is definitely not recommended to use this flag. |
415 | |
441 | |
416 | =back |
442 | =back |
417 | |
443 | |
418 | If one or more of these are ored into the flags value, then only these |
444 | 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 |
445 | 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 |
446 | specified, all backends in C<ev_recommended_backends ()> will be tried. |
421 | order of their flag values :) |
|
|
422 | |
447 | |
423 | The most typical usage is like this: |
448 | The most typical usage is like this: |
424 | |
449 | |
425 | if (!ev_default_loop (0)) |
450 | if (!ev_default_loop (0)) |
426 | fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?"); |
451 | fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?"); |
… | |
… | |
473 | Like C<ev_default_destroy>, but destroys an event loop created by an |
498 | Like C<ev_default_destroy>, but destroys an event loop created by an |
474 | earlier call to C<ev_loop_new>. |
499 | earlier call to C<ev_loop_new>. |
475 | |
500 | |
476 | =item ev_default_fork () |
501 | =item ev_default_fork () |
477 | |
502 | |
|
|
503 | This function sets a flag that causes subsequent C<ev_loop> iterations |
478 | This function reinitialises the kernel state for backends that have |
504 | 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 |
505 | 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 |
506 | the child process (or both child and parent, but that again makes little |
481 | again makes little sense). |
507 | sense). You I<must> call it in the child before using any of the libev |
|
|
508 | functions, and it will only take effect at the next C<ev_loop> iteration. |
482 | |
509 | |
483 | You I<must> call this function in the child process after forking if and |
510 | 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 |
511 | 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. |
512 | you just fork+exec, you don't have to call it at all. |
486 | |
513 | |
487 | The function itself is quite fast and it's usually not a problem to call |
514 | 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 |
515 | 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>: |
516 | quite nicely into a call to C<pthread_atfork>: |
490 | |
517 | |
491 | pthread_atfork (0, 0, ev_default_fork); |
518 | pthread_atfork (0, 0, ev_default_fork); |
492 | |
519 | |
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) |
520 | =item ev_loop_fork (loop) |
498 | |
521 | |
499 | Like C<ev_default_fork>, but acts on an event loop created by |
522 | 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 |
523 | 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. |
524 | after fork, and how you do this is entirely your own problem. |
|
|
525 | |
|
|
526 | =item int ev_is_default_loop (loop) |
|
|
527 | |
|
|
528 | Returns true when the given loop actually is the default loop, false otherwise. |
502 | |
529 | |
503 | =item unsigned int ev_loop_count (loop) |
530 | =item unsigned int ev_loop_count (loop) |
504 | |
531 | |
505 | Returns the count of loop iterations for the loop, which is identical to |
532 | 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 |
533 | 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. |
578 | usually a better approach for this kind of thing. |
552 | |
579 | |
553 | Here are the gory details of what C<ev_loop> does: |
580 | Here are the gory details of what C<ev_loop> does: |
554 | |
581 | |
555 | - Before the first iteration, call any pending watchers. |
582 | - Before the first iteration, call any pending watchers. |
556 | * If there are no active watchers (reference count is zero), return. |
583 | * If EVFLAG_FORKCHECK was used, check for a fork. |
557 | - Queue all prepare watchers and then call all outstanding watchers. |
584 | - If a fork was detected, queue and call all fork watchers. |
|
|
585 | - Queue and call all prepare watchers. |
558 | - If we have been forked, recreate the kernel state. |
586 | - If we have been forked, recreate the kernel state. |
559 | - Update the kernel state with all outstanding changes. |
587 | - Update the kernel state with all outstanding changes. |
560 | - Update the "event loop time". |
588 | - Update the "event loop time". |
561 | - Calculate for how long to block. |
589 | - Calculate for how long to sleep or block, if at all |
|
|
590 | (active idle watchers, EVLOOP_NONBLOCK or not having |
|
|
591 | any active watchers at all will result in not sleeping). |
|
|
592 | - Sleep if the I/O and timer collect interval say so. |
562 | - Block the process, waiting for any events. |
593 | - Block the process, waiting for any events. |
563 | - Queue all outstanding I/O (fd) events. |
594 | - Queue all outstanding I/O (fd) events. |
564 | - Update the "event loop time" and do time jump handling. |
595 | - Update the "event loop time" and do time jump handling. |
565 | - Queue all outstanding timers. |
596 | - Queue all outstanding timers. |
566 | - Queue all outstanding periodics. |
597 | - Queue all outstanding periodics. |
567 | - If no events are pending now, queue all idle watchers. |
598 | - If no events are pending now, queue all idle watchers. |
568 | - Queue all check watchers. |
599 | - Queue all check watchers. |
569 | - Call all queued watchers in reverse order (i.e. check watchers first). |
600 | - 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 |
601 | Signals and child watchers are implemented as I/O watchers, and will |
571 | be handled here by queueing them when their watcher gets executed. |
602 | be handled here by queueing them when their watcher gets executed. |
572 | - If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
603 | - If ev_unloop has been called, or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
573 | were used, return, otherwise continue with step *. |
604 | were used, or there are no active watchers, return, otherwise |
|
|
605 | continue with step *. |
574 | |
606 | |
575 | Example: Queue some jobs and then loop until no events are outsanding |
607 | Example: Queue some jobs and then loop until no events are outstanding |
576 | anymore. |
608 | anymore. |
577 | |
609 | |
578 | ... queue jobs here, make sure they register event watchers as long |
610 | ... 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..) |
611 | ... as they still have work to do (even an idle watcher will do..) |
580 | ev_loop (my_loop, 0); |
612 | ev_loop (my_loop, 0); |
… | |
… | |
584 | |
616 | |
585 | Can be used to make a call to C<ev_loop> return early (but only after it |
617 | 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 |
618 | 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 |
619 | 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. |
620 | C<EVUNLOOP_ALL>, which will make all nested C<ev_loop> calls return. |
|
|
621 | |
|
|
622 | This "unloop state" will be cleared when entering C<ev_loop> again. |
589 | |
623 | |
590 | =item ev_ref (loop) |
624 | =item ev_ref (loop) |
591 | |
625 | |
592 | =item ev_unref (loop) |
626 | =item ev_unref (loop) |
593 | |
627 | |
… | |
… | |
598 | returning, ev_unref() after starting, and ev_ref() before stopping it. For |
632 | 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 |
633 | 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 |
634 | 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 |
635 | 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 |
636 | 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>. |
637 | libraries. Just remember to I<unref after start> and I<ref before stop> |
|
|
638 | (but only if the watcher wasn't active before, or was active before, |
|
|
639 | respectively). |
604 | |
640 | |
605 | Example: Create a signal watcher, but keep it from keeping C<ev_loop> |
641 | Example: Create a signal watcher, but keep it from keeping C<ev_loop> |
606 | running when nothing else is active. |
642 | running when nothing else is active. |
607 | |
643 | |
608 | struct ev_signal exitsig; |
644 | struct ev_signal exitsig; |
… | |
… | |
756 | |
792 | |
757 | =item C<EV_FORK> |
793 | =item C<EV_FORK> |
758 | |
794 | |
759 | The event loop has been resumed in the child process after fork (see |
795 | The event loop has been resumed in the child process after fork (see |
760 | C<ev_fork>). |
796 | C<ev_fork>). |
|
|
797 | |
|
|
798 | =item C<EV_ASYNC> |
|
|
799 | |
|
|
800 | The given async watcher has been asynchronously notified (see C<ev_async>). |
761 | |
801 | |
762 | =item C<EV_ERROR> |
802 | =item C<EV_ERROR> |
763 | |
803 | |
764 | An unspecified error has occured, the watcher has been stopped. This might |
804 | An unspecified error has occured, the watcher has been stopped. This might |
765 | happen because the watcher could not be properly started because libev |
805 | happen because the watcher could not be properly started because libev |
… | |
… | |
1068 | |
1108 | |
1069 | The events being watched. |
1109 | The events being watched. |
1070 | |
1110 | |
1071 | =back |
1111 | =back |
1072 | |
1112 | |
|
|
1113 | =head3 Examples |
|
|
1114 | |
1073 | Example: Call C<stdin_readable_cb> when STDIN_FILENO has become, well |
1115 | Example: Call C<stdin_readable_cb> when STDIN_FILENO has become, well |
1074 | readable, but only once. Since it is likely line-buffered, you could |
1116 | readable, but only once. Since it is likely line-buffered, you could |
1075 | attempt to read a whole line in the callback. |
1117 | attempt to read a whole line in the callback. |
1076 | |
1118 | |
1077 | static void |
1119 | static void |
… | |
… | |
1129 | configure a timer to trigger every 10 seconds, then it will trigger at |
1171 | configure a timer to trigger every 10 seconds, then it will trigger at |
1130 | exactly 10 second intervals. If, however, your program cannot keep up with |
1172 | exactly 10 second intervals. If, however, your program cannot keep up with |
1131 | the timer (because it takes longer than those 10 seconds to do stuff) the |
1173 | the timer (because it takes longer than those 10 seconds to do stuff) the |
1132 | timer will not fire more than once per event loop iteration. |
1174 | timer will not fire more than once per event loop iteration. |
1133 | |
1175 | |
1134 | =item ev_timer_again (loop) |
1176 | =item ev_timer_again (loop, ev_timer *) |
1135 | |
1177 | |
1136 | This will act as if the timer timed out and restart it again if it is |
1178 | This will act as if the timer timed out and restart it again if it is |
1137 | repeating. The exact semantics are: |
1179 | repeating. The exact semantics are: |
1138 | |
1180 | |
1139 | If the timer is pending, its pending status is cleared. |
1181 | If the timer is pending, its pending status is cleared. |
… | |
… | |
1174 | or C<ev_timer_again> is called and determines the next timeout (if any), |
1216 | or C<ev_timer_again> is called and determines the next timeout (if any), |
1175 | which is also when any modifications are taken into account. |
1217 | which is also when any modifications are taken into account. |
1176 | |
1218 | |
1177 | =back |
1219 | =back |
1178 | |
1220 | |
|
|
1221 | =head3 Examples |
|
|
1222 | |
1179 | Example: Create a timer that fires after 60 seconds. |
1223 | Example: Create a timer that fires after 60 seconds. |
1180 | |
1224 | |
1181 | static void |
1225 | static void |
1182 | one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
1226 | one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
1183 | { |
1227 | { |
… | |
… | |
1246 | In this configuration the watcher triggers an event at the wallclock time |
1290 | In this configuration the watcher triggers an event at the wallclock time |
1247 | C<at> and doesn't repeat. It will not adjust when a time jump occurs, |
1291 | C<at> and doesn't repeat. It will not adjust when a time jump occurs, |
1248 | that is, if it is to be run at January 1st 2011 then it will run when the |
1292 | that is, if it is to be run at January 1st 2011 then it will run when the |
1249 | system time reaches or surpasses this time. |
1293 | system time reaches or surpasses this time. |
1250 | |
1294 | |
1251 | =item * non-repeating interval timer (at = offset, interval > 0, reschedule_cb = 0) |
1295 | =item * repeating interval timer (at = offset, interval > 0, reschedule_cb = 0) |
1252 | |
1296 | |
1253 | In this mode the watcher will always be scheduled to time out at the next |
1297 | In this mode the watcher will always be scheduled to time out at the next |
1254 | C<at + N * interval> time (for some integer N, which can also be negative) |
1298 | C<at + N * interval> time (for some integer N, which can also be negative) |
1255 | and then repeat, regardless of any time jumps. |
1299 | and then repeat, regardless of any time jumps. |
1256 | |
1300 | |
… | |
… | |
1339 | |
1383 | |
1340 | When active, contains the absolute time that the watcher is supposed to |
1384 | When active, contains the absolute time that the watcher is supposed to |
1341 | trigger next. |
1385 | trigger next. |
1342 | |
1386 | |
1343 | =back |
1387 | =back |
|
|
1388 | |
|
|
1389 | =head3 Examples |
1344 | |
1390 | |
1345 | Example: Call a callback every hour, or, more precisely, whenever the |
1391 | Example: Call a callback every hour, or, more precisely, whenever the |
1346 | system clock is divisible by 3600. The callback invocation times have |
1392 | system clock is divisible by 3600. The callback invocation times have |
1347 | potentially a lot of jittering, but good long-term stability. |
1393 | potentially a lot of jittering, but good long-term stability. |
1348 | |
1394 | |
… | |
… | |
1388 | with the kernel (thus it coexists with your own signal handlers as long |
1434 | with the kernel (thus it coexists with your own signal handlers as long |
1389 | as you don't register any with libev). Similarly, when the last signal |
1435 | as you don't register any with libev). Similarly, when the last signal |
1390 | watcher for a signal is stopped libev will reset the signal handler to |
1436 | watcher for a signal is stopped libev will reset the signal handler to |
1391 | SIG_DFL (regardless of what it was set to before). |
1437 | SIG_DFL (regardless of what it was set to before). |
1392 | |
1438 | |
|
|
1439 | If possible and supported, libev will install its handlers with |
|
|
1440 | C<SA_RESTART> behaviour enabled, so syscalls should not be unduly |
|
|
1441 | interrupted. If you have a problem with syscalls getting interrupted by |
|
|
1442 | signals you can block all signals in an C<ev_check> watcher and unblock |
|
|
1443 | them in an C<ev_prepare> watcher. |
|
|
1444 | |
1393 | =head3 Watcher-Specific Functions and Data Members |
1445 | =head3 Watcher-Specific Functions and Data Members |
1394 | |
1446 | |
1395 | =over 4 |
1447 | =over 4 |
1396 | |
1448 | |
1397 | =item ev_signal_init (ev_signal *, callback, int signum) |
1449 | =item ev_signal_init (ev_signal *, callback, int signum) |
… | |
… | |
1405 | |
1457 | |
1406 | The signal the watcher watches out for. |
1458 | The signal the watcher watches out for. |
1407 | |
1459 | |
1408 | =back |
1460 | =back |
1409 | |
1461 | |
|
|
1462 | =head3 Examples |
|
|
1463 | |
|
|
1464 | Example: Try to exit cleanly on SIGINT and SIGTERM. |
|
|
1465 | |
|
|
1466 | static void |
|
|
1467 | sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) |
|
|
1468 | { |
|
|
1469 | ev_unloop (loop, EVUNLOOP_ALL); |
|
|
1470 | } |
|
|
1471 | |
|
|
1472 | struct ev_signal signal_watcher; |
|
|
1473 | ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
|
|
1474 | ev_signal_start (loop, &sigint_cb); |
|
|
1475 | |
1410 | |
1476 | |
1411 | =head2 C<ev_child> - watch out for process status changes |
1477 | =head2 C<ev_child> - watch out for process status changes |
1412 | |
1478 | |
1413 | Child watchers trigger when your process receives a SIGCHLD in response to |
1479 | Child watchers trigger when your process receives a SIGCHLD in response to |
1414 | some child status changes (most typically when a child of yours dies). |
1480 | some child status changes (most typically when a child of yours dies). It |
|
|
1481 | is permissible to install a child watcher I<after> the child has been |
|
|
1482 | forked (which implies it might have already exited), as long as the event |
|
|
1483 | loop isn't entered (or is continued from a watcher). |
|
|
1484 | |
|
|
1485 | Only the default event loop is capable of handling signals, and therefore |
|
|
1486 | you can only rgeister child watchers in the default event loop. |
|
|
1487 | |
|
|
1488 | =head3 Process Interaction |
|
|
1489 | |
|
|
1490 | Libev grabs C<SIGCHLD> as soon as the default event loop is |
|
|
1491 | initialised. This is necessary to guarantee proper behaviour even if |
|
|
1492 | the first child watcher is started after the child exits. The occurance |
|
|
1493 | of C<SIGCHLD> is recorded asynchronously, but child reaping is done |
|
|
1494 | synchronously as part of the event loop processing. Libev always reaps all |
|
|
1495 | children, even ones not watched. |
|
|
1496 | |
|
|
1497 | =head3 Overriding the Built-In Processing |
|
|
1498 | |
|
|
1499 | Libev offers no special support for overriding the built-in child |
|
|
1500 | processing, but if your application collides with libev's default child |
|
|
1501 | handler, you can override it easily by installing your own handler for |
|
|
1502 | C<SIGCHLD> after initialising the default loop, and making sure the |
|
|
1503 | default loop never gets destroyed. You are encouraged, however, to use an |
|
|
1504 | event-based approach to child reaping and thus use libev's support for |
|
|
1505 | that, so other libev users can use C<ev_child> watchers freely. |
1415 | |
1506 | |
1416 | =head3 Watcher-Specific Functions and Data Members |
1507 | =head3 Watcher-Specific Functions and Data Members |
1417 | |
1508 | |
1418 | =over 4 |
1509 | =over 4 |
1419 | |
1510 | |
1420 | =item ev_child_init (ev_child *, callback, int pid) |
1511 | =item ev_child_init (ev_child *, callback, int pid, int trace) |
1421 | |
1512 | |
1422 | =item ev_child_set (ev_child *, int pid) |
1513 | =item ev_child_set (ev_child *, int pid, int trace) |
1423 | |
1514 | |
1424 | Configures the watcher to wait for status changes of process C<pid> (or |
1515 | Configures the watcher to wait for status changes of process C<pid> (or |
1425 | I<any> process if C<pid> is specified as C<0>). The callback can look |
1516 | I<any> process if C<pid> is specified as C<0>). The callback can look |
1426 | at the C<rstatus> member of the C<ev_child> watcher structure to see |
1517 | at the C<rstatus> member of the C<ev_child> watcher structure to see |
1427 | the status word (use the macros from C<sys/wait.h> and see your systems |
1518 | the status word (use the macros from C<sys/wait.h> and see your systems |
1428 | C<waitpid> documentation). The C<rpid> member contains the pid of the |
1519 | C<waitpid> documentation). The C<rpid> member contains the pid of the |
1429 | process causing the status change. |
1520 | process causing the status change. C<trace> must be either C<0> (only |
|
|
1521 | activate the watcher when the process terminates) or C<1> (additionally |
|
|
1522 | activate the watcher when the process is stopped or continued). |
1430 | |
1523 | |
1431 | =item int pid [read-only] |
1524 | =item int pid [read-only] |
1432 | |
1525 | |
1433 | The process id this watcher watches out for, or C<0>, meaning any process id. |
1526 | The process id this watcher watches out for, or C<0>, meaning any process id. |
1434 | |
1527 | |
… | |
… | |
1441 | The process exit/trace status caused by C<rpid> (see your systems |
1534 | The process exit/trace status caused by C<rpid> (see your systems |
1442 | C<waitpid> and C<sys/wait.h> documentation for details). |
1535 | C<waitpid> and C<sys/wait.h> documentation for details). |
1443 | |
1536 | |
1444 | =back |
1537 | =back |
1445 | |
1538 | |
1446 | Example: Try to exit cleanly on SIGINT and SIGTERM. |
1539 | =head3 Examples |
|
|
1540 | |
|
|
1541 | Example: C<fork()> a new process and install a child handler to wait for |
|
|
1542 | its completion. |
|
|
1543 | |
|
|
1544 | ev_child cw; |
1447 | |
1545 | |
1448 | static void |
1546 | static void |
1449 | sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) |
1547 | child_cb (EV_P_ struct ev_child *w, int revents) |
1450 | { |
1548 | { |
1451 | ev_unloop (loop, EVUNLOOP_ALL); |
1549 | ev_child_stop (EV_A_ w); |
|
|
1550 | printf ("process %d exited with status %x\n", w->rpid, w->rstatus); |
1452 | } |
1551 | } |
1453 | |
1552 | |
1454 | struct ev_signal signal_watcher; |
1553 | pid_t pid = fork (); |
1455 | ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
1554 | |
1456 | ev_signal_start (loop, &sigint_cb); |
1555 | if (pid < 0) |
|
|
1556 | // error |
|
|
1557 | else if (pid == 0) |
|
|
1558 | { |
|
|
1559 | // the forked child executes here |
|
|
1560 | exit (1); |
|
|
1561 | } |
|
|
1562 | else |
|
|
1563 | { |
|
|
1564 | ev_child_init (&cw, child_cb, pid, 0); |
|
|
1565 | ev_child_start (EV_DEFAULT_ &cw); |
|
|
1566 | } |
1457 | |
1567 | |
1458 | |
1568 | |
1459 | =head2 C<ev_stat> - did the file attributes just change? |
1569 | =head2 C<ev_stat> - did the file attributes just change? |
1460 | |
1570 | |
1461 | This watches a filesystem path for attribute changes. That is, it calls |
1571 | This watches a filesystem path for attribute changes. That is, it calls |
… | |
… | |
1541 | |
1651 | |
1542 | The callback will be receive C<EV_STAT> when a change was detected, |
1652 | The callback will be receive C<EV_STAT> when a change was detected, |
1543 | relative to the attributes at the time the watcher was started (or the |
1653 | relative to the attributes at the time the watcher was started (or the |
1544 | last change was detected). |
1654 | last change was detected). |
1545 | |
1655 | |
1546 | =item ev_stat_stat (ev_stat *) |
1656 | =item ev_stat_stat (loop, ev_stat *) |
1547 | |
1657 | |
1548 | Updates the stat buffer immediately with new values. If you change the |
1658 | Updates the stat buffer immediately with new values. If you change the |
1549 | watched path in your callback, you could call this fucntion to avoid |
1659 | watched path in your callback, you could call this fucntion to avoid |
1550 | detecting this change (while introducing a race condition). Can also be |
1660 | detecting this change (while introducing a race condition). Can also be |
1551 | useful simply to find out the new values. |
1661 | useful simply to find out the new values. |
… | |
… | |
1658 | kind. There is a C<ev_idle_set> macro, but using it is utterly pointless, |
1768 | kind. There is a C<ev_idle_set> macro, but using it is utterly pointless, |
1659 | believe me. |
1769 | believe me. |
1660 | |
1770 | |
1661 | =back |
1771 | =back |
1662 | |
1772 | |
|
|
1773 | =head3 Examples |
|
|
1774 | |
1663 | Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the |
1775 | Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the |
1664 | callback, free it. Also, use no error checking, as usual. |
1776 | callback, free it. Also, use no error checking, as usual. |
1665 | |
1777 | |
1666 | static void |
1778 | static void |
1667 | idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents) |
1779 | idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents) |
1668 | { |
1780 | { |
1669 | free (w); |
1781 | free (w); |
1670 | // now do something you wanted to do when the program has |
1782 | // now do something you wanted to do when the program has |
1671 | // no longer asnything immediate to do. |
1783 | // no longer anything immediate to do. |
1672 | } |
1784 | } |
1673 | |
1785 | |
1674 | struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle)); |
1786 | struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle)); |
1675 | ev_idle_init (idle_watcher, idle_cb); |
1787 | ev_idle_init (idle_watcher, idle_cb); |
1676 | ev_idle_start (loop, idle_cb); |
1788 | ev_idle_start (loop, idle_cb); |
… | |
… | |
1738 | parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set> |
1850 | parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set> |
1739 | macros, but using them is utterly, utterly and completely pointless. |
1851 | macros, but using them is utterly, utterly and completely pointless. |
1740 | |
1852 | |
1741 | =back |
1853 | =back |
1742 | |
1854 | |
|
|
1855 | =head3 Examples |
|
|
1856 | |
1743 | There are a number of principal ways to embed other event loops or modules |
1857 | There are a number of principal ways to embed other event loops or modules |
1744 | into libev. Here are some ideas on how to include libadns into libev |
1858 | into libev. Here are some ideas on how to include libadns into libev |
1745 | (there is a Perl module named C<EV::ADNS> that does this, which you could |
1859 | (there is a Perl module named C<EV::ADNS> that does this, which you could |
1746 | use for an actually working example. Another Perl module named C<EV::Glib> |
1860 | use for an actually working example. Another Perl module named C<EV::Glib> |
1747 | embeds a Glib main context into libev, and finally, C<Glib::EV> embeds EV |
1861 | embeds a Glib main context into libev, and finally, C<Glib::EV> embeds EV |
… | |
… | |
1915 | portable one. |
2029 | portable one. |
1916 | |
2030 | |
1917 | So when you want to use this feature you will always have to be prepared |
2031 | So when you want to use this feature you will always have to be prepared |
1918 | that you cannot get an embeddable loop. The recommended way to get around |
2032 | that you cannot get an embeddable loop. The recommended way to get around |
1919 | this is to have a separate variables for your embeddable loop, try to |
2033 | this is to have a separate variables for your embeddable loop, try to |
1920 | create it, and if that fails, use the normal loop for everything: |
2034 | create it, and if that fails, use the normal loop for everything. |
|
|
2035 | |
|
|
2036 | =head3 Watcher-Specific Functions and Data Members |
|
|
2037 | |
|
|
2038 | =over 4 |
|
|
2039 | |
|
|
2040 | =item ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop) |
|
|
2041 | |
|
|
2042 | =item ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop) |
|
|
2043 | |
|
|
2044 | Configures the watcher to embed the given loop, which must be |
|
|
2045 | embeddable. If the callback is C<0>, then C<ev_embed_sweep> will be |
|
|
2046 | invoked automatically, otherwise it is the responsibility of the callback |
|
|
2047 | to invoke it (it will continue to be called until the sweep has been done, |
|
|
2048 | if you do not want thta, you need to temporarily stop the embed watcher). |
|
|
2049 | |
|
|
2050 | =item ev_embed_sweep (loop, ev_embed *) |
|
|
2051 | |
|
|
2052 | Make a single, non-blocking sweep over the embedded loop. This works |
|
|
2053 | similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most |
|
|
2054 | apropriate way for embedded loops. |
|
|
2055 | |
|
|
2056 | =item struct ev_loop *other [read-only] |
|
|
2057 | |
|
|
2058 | The embedded event loop. |
|
|
2059 | |
|
|
2060 | =back |
|
|
2061 | |
|
|
2062 | =head3 Examples |
|
|
2063 | |
|
|
2064 | Example: Try to get an embeddable event loop and embed it into the default |
|
|
2065 | event loop. If that is not possible, use the default loop. The default |
|
|
2066 | loop is stored in C<loop_hi>, while the mebeddable loop is stored in |
|
|
2067 | C<loop_lo> (which is C<loop_hi> in the acse no embeddable loop can be |
|
|
2068 | used). |
1921 | |
2069 | |
1922 | struct ev_loop *loop_hi = ev_default_init (0); |
2070 | struct ev_loop *loop_hi = ev_default_init (0); |
1923 | struct ev_loop *loop_lo = 0; |
2071 | struct ev_loop *loop_lo = 0; |
1924 | struct ev_embed embed; |
2072 | struct ev_embed embed; |
1925 | |
2073 | |
… | |
… | |
1936 | ev_embed_start (loop_hi, &embed); |
2084 | ev_embed_start (loop_hi, &embed); |
1937 | } |
2085 | } |
1938 | else |
2086 | else |
1939 | loop_lo = loop_hi; |
2087 | loop_lo = loop_hi; |
1940 | |
2088 | |
1941 | =head3 Watcher-Specific Functions and Data Members |
2089 | Example: Check if kqueue is available but not recommended and create |
|
|
2090 | a kqueue backend for use with sockets (which usually work with any |
|
|
2091 | kqueue implementation). Store the kqueue/socket-only event loop in |
|
|
2092 | C<loop_socket>. (One might optionally use C<EVFLAG_NOENV>, too). |
1942 | |
2093 | |
1943 | =over 4 |
2094 | struct ev_loop *loop = ev_default_init (0); |
|
|
2095 | struct ev_loop *loop_socket = 0; |
|
|
2096 | struct ev_embed embed; |
|
|
2097 | |
|
|
2098 | if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE) |
|
|
2099 | if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE)) |
|
|
2100 | { |
|
|
2101 | ev_embed_init (&embed, 0, loop_socket); |
|
|
2102 | ev_embed_start (loop, &embed); |
|
|
2103 | } |
1944 | |
2104 | |
1945 | =item ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop) |
2105 | if (!loop_socket) |
|
|
2106 | loop_socket = loop; |
1946 | |
2107 | |
1947 | =item ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop) |
2108 | // now use loop_socket for all sockets, and loop for everything else |
1948 | |
|
|
1949 | Configures the watcher to embed the given loop, which must be |
|
|
1950 | embeddable. If the callback is C<0>, then C<ev_embed_sweep> will be |
|
|
1951 | invoked automatically, otherwise it is the responsibility of the callback |
|
|
1952 | to invoke it (it will continue to be called until the sweep has been done, |
|
|
1953 | if you do not want thta, you need to temporarily stop the embed watcher). |
|
|
1954 | |
|
|
1955 | =item ev_embed_sweep (loop, ev_embed *) |
|
|
1956 | |
|
|
1957 | Make a single, non-blocking sweep over the embedded loop. This works |
|
|
1958 | similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most |
|
|
1959 | apropriate way for embedded loops. |
|
|
1960 | |
|
|
1961 | =item struct ev_loop *other [read-only] |
|
|
1962 | |
|
|
1963 | The embedded event loop. |
|
|
1964 | |
|
|
1965 | =back |
|
|
1966 | |
2109 | |
1967 | |
2110 | |
1968 | =head2 C<ev_fork> - the audacity to resume the event loop after a fork |
2111 | =head2 C<ev_fork> - the audacity to resume the event loop after a fork |
1969 | |
2112 | |
1970 | Fork watchers are called when a C<fork ()> was detected (usually because |
2113 | Fork watchers are called when a C<fork ()> was detected (usually because |
… | |
… | |
1986 | believe me. |
2129 | believe me. |
1987 | |
2130 | |
1988 | =back |
2131 | =back |
1989 | |
2132 | |
1990 | |
2133 | |
|
|
2134 | =head2 C<ev_async> - how to wake up another event loop |
|
|
2135 | |
|
|
2136 | In general, you cannot use an C<ev_loop> from multiple threads or other |
|
|
2137 | asynchronous sources such as signal handlers (as opposed to multiple event |
|
|
2138 | loops - those are of course safe to use in different threads). |
|
|
2139 | |
|
|
2140 | Sometimes, however, you need to wake up another event loop you do not |
|
|
2141 | control, for example because it belongs to another thread. This is what |
|
|
2142 | C<ev_async> watchers do: as long as the C<ev_async> watcher is active, you |
|
|
2143 | can signal it by calling C<ev_async_send>, which is thread- and signal |
|
|
2144 | safe. |
|
|
2145 | |
|
|
2146 | This functionality is very similar to C<ev_signal> watchers, as signals, |
|
|
2147 | too, are asynchronous in nature, and signals, too, will be compressed |
|
|
2148 | (i.e. the number of callback invocations may be less than the number of |
|
|
2149 | C<ev_async_sent> calls). |
|
|
2150 | |
|
|
2151 | Unlike C<ev_signal> watchers, C<ev_async> works with any event loop, not |
|
|
2152 | just the default loop. |
|
|
2153 | |
|
|
2154 | =head3 Queueing |
|
|
2155 | |
|
|
2156 | C<ev_async> does not support queueing of data in any way. The reason |
|
|
2157 | is that the author does not know of a simple (or any) algorithm for a |
|
|
2158 | multiple-writer-single-reader queue that works in all cases and doesn't |
|
|
2159 | need elaborate support such as pthreads. |
|
|
2160 | |
|
|
2161 | That means that if you want to queue data, you have to provide your own |
|
|
2162 | queue. But at least I can tell you would implement locking around your |
|
|
2163 | queue: |
|
|
2164 | |
|
|
2165 | =over 4 |
|
|
2166 | |
|
|
2167 | =item queueing from a signal handler context |
|
|
2168 | |
|
|
2169 | To implement race-free queueing, you simply add to the queue in the signal |
|
|
2170 | handler but you block the signal handler in the watcher callback. Here is an example that does that for |
|
|
2171 | some fictitiuous SIGUSR1 handler: |
|
|
2172 | |
|
|
2173 | static ev_async mysig; |
|
|
2174 | |
|
|
2175 | static void |
|
|
2176 | sigusr1_handler (void) |
|
|
2177 | { |
|
|
2178 | sometype data; |
|
|
2179 | |
|
|
2180 | // no locking etc. |
|
|
2181 | queue_put (data); |
|
|
2182 | ev_async_send (EV_DEFAULT_ &mysig); |
|
|
2183 | } |
|
|
2184 | |
|
|
2185 | static void |
|
|
2186 | mysig_cb (EV_P_ ev_async *w, int revents) |
|
|
2187 | { |
|
|
2188 | sometype data; |
|
|
2189 | sigset_t block, prev; |
|
|
2190 | |
|
|
2191 | sigemptyset (&block); |
|
|
2192 | sigaddset (&block, SIGUSR1); |
|
|
2193 | sigprocmask (SIG_BLOCK, &block, &prev); |
|
|
2194 | |
|
|
2195 | while (queue_get (&data)) |
|
|
2196 | process (data); |
|
|
2197 | |
|
|
2198 | if (sigismember (&prev, SIGUSR1) |
|
|
2199 | sigprocmask (SIG_UNBLOCK, &block, 0); |
|
|
2200 | } |
|
|
2201 | |
|
|
2202 | (Note: pthreads in theory requires you to use C<pthread_setmask> |
|
|
2203 | instead of C<sigprocmask> when you use threads, but libev doesn't do it |
|
|
2204 | either...). |
|
|
2205 | |
|
|
2206 | =item queueing from a thread context |
|
|
2207 | |
|
|
2208 | The strategy for threads is different, as you cannot (easily) block |
|
|
2209 | threads but you can easily preempt them, so to queue safely you need to |
|
|
2210 | employ a traditional mutex lock, such as in this pthread example: |
|
|
2211 | |
|
|
2212 | static ev_async mysig; |
|
|
2213 | static pthread_mutex_t mymutex = PTHREAD_MUTEX_INITIALIZER; |
|
|
2214 | |
|
|
2215 | static void |
|
|
2216 | otherthread (void) |
|
|
2217 | { |
|
|
2218 | // only need to lock the actual queueing operation |
|
|
2219 | pthread_mutex_lock (&mymutex); |
|
|
2220 | queue_put (data); |
|
|
2221 | pthread_mutex_unlock (&mymutex); |
|
|
2222 | |
|
|
2223 | ev_async_send (EV_DEFAULT_ &mysig); |
|
|
2224 | } |
|
|
2225 | |
|
|
2226 | static void |
|
|
2227 | mysig_cb (EV_P_ ev_async *w, int revents) |
|
|
2228 | { |
|
|
2229 | pthread_mutex_lock (&mymutex); |
|
|
2230 | |
|
|
2231 | while (queue_get (&data)) |
|
|
2232 | process (data); |
|
|
2233 | |
|
|
2234 | pthread_mutex_unlock (&mymutex); |
|
|
2235 | } |
|
|
2236 | |
|
|
2237 | =back |
|
|
2238 | |
|
|
2239 | |
|
|
2240 | =head3 Watcher-Specific Functions and Data Members |
|
|
2241 | |
|
|
2242 | =over 4 |
|
|
2243 | |
|
|
2244 | =item ev_async_init (ev_async *, callback) |
|
|
2245 | |
|
|
2246 | Initialises and configures the async watcher - it has no parameters of any |
|
|
2247 | kind. There is a C<ev_asynd_set> macro, but using it is utterly pointless, |
|
|
2248 | believe me. |
|
|
2249 | |
|
|
2250 | =item ev_async_send (loop, ev_async *) |
|
|
2251 | |
|
|
2252 | Sends/signals/activates the given C<ev_async> watcher, that is, feeds |
|
|
2253 | an C<EV_ASYNC> event on the watcher into the event loop. Unlike |
|
|
2254 | C<ev_feed_event>, this call is safe to do in other threads, signal or |
|
|
2255 | similar contexts (see the dicusssion of C<EV_ATOMIC_T> in the embedding |
|
|
2256 | section below on what exactly this means). |
|
|
2257 | |
|
|
2258 | This call incurs the overhead of a syscall only once per loop iteration, |
|
|
2259 | so while the overhead might be noticable, it doesn't apply to repeated |
|
|
2260 | calls to C<ev_async_send>. |
|
|
2261 | |
|
|
2262 | =back |
|
|
2263 | |
|
|
2264 | |
1991 | =head1 OTHER FUNCTIONS |
2265 | =head1 OTHER FUNCTIONS |
1992 | |
2266 | |
1993 | There are some other functions of possible interest. Described. Here. Now. |
2267 | There are some other functions of possible interest. Described. Here. Now. |
1994 | |
2268 | |
1995 | =over 4 |
2269 | =over 4 |
… | |
… | |
2222 | Example: Define a class with an IO and idle watcher, start one of them in |
2496 | Example: Define a class with an IO and idle watcher, start one of them in |
2223 | the constructor. |
2497 | the constructor. |
2224 | |
2498 | |
2225 | class myclass |
2499 | class myclass |
2226 | { |
2500 | { |
2227 | ev_io io; void io_cb (ev::io &w, int revents); |
2501 | ev::io io; void io_cb (ev::io &w, int revents); |
2228 | ev_idle idle void idle_cb (ev::idle &w, int revents); |
2502 | ev:idle idle void idle_cb (ev::idle &w, int revents); |
2229 | |
2503 | |
2230 | myclass (); |
2504 | myclass (int fd) |
2231 | } |
|
|
2232 | |
|
|
2233 | myclass::myclass (int fd) |
|
|
2234 | { |
2505 | { |
2235 | io .set <myclass, &myclass::io_cb > (this); |
2506 | io .set <myclass, &myclass::io_cb > (this); |
2236 | idle.set <myclass, &myclass::idle_cb> (this); |
2507 | idle.set <myclass, &myclass::idle_cb> (this); |
2237 | |
2508 | |
2238 | io.start (fd, ev::READ); |
2509 | io.start (fd, ev::READ); |
|
|
2510 | } |
2239 | } |
2511 | }; |
|
|
2512 | |
|
|
2513 | |
|
|
2514 | =head1 OTHER LANGUAGE BINDINGS |
|
|
2515 | |
|
|
2516 | Libev does not offer other language bindings itself, but bindings for a |
|
|
2517 | numbe rof languages exist in the form of third-party packages. If you know |
|
|
2518 | any interesting language binding in addition to the ones listed here, drop |
|
|
2519 | me a note. |
|
|
2520 | |
|
|
2521 | =over 4 |
|
|
2522 | |
|
|
2523 | =item Perl |
|
|
2524 | |
|
|
2525 | The EV module implements the full libev API and is actually used to test |
|
|
2526 | libev. EV is developed together with libev. Apart from the EV core module, |
|
|
2527 | there are additional modules that implement libev-compatible interfaces |
|
|
2528 | to C<libadns> (C<EV::ADNS>), C<Net::SNMP> (C<Net::SNMP::EV>) and the |
|
|
2529 | C<libglib> event core (C<Glib::EV> and C<EV::Glib>). |
|
|
2530 | |
|
|
2531 | It can be found and installed via CPAN, its homepage is found at |
|
|
2532 | L<http://software.schmorp.de/pkg/EV>. |
|
|
2533 | |
|
|
2534 | =item Ruby |
|
|
2535 | |
|
|
2536 | Tony Arcieri has written a ruby extension that offers access to a subset |
|
|
2537 | of the libev API and adds filehandle abstractions, asynchronous DNS and |
|
|
2538 | more on top of it. It can be found via gem servers. Its homepage is at |
|
|
2539 | L<http://rev.rubyforge.org/>. |
|
|
2540 | |
|
|
2541 | =item D |
|
|
2542 | |
|
|
2543 | Leandro Lucarella has written a D language binding (F<ev.d>) for libev, to |
|
|
2544 | be found at L<http://git.llucax.com.ar/?p=software/ev.d.git;a=summary>. |
|
|
2545 | |
|
|
2546 | =back |
2240 | |
2547 | |
2241 | |
2548 | |
2242 | =head1 MACRO MAGIC |
2549 | =head1 MACRO MAGIC |
2243 | |
2550 | |
2244 | Libev can be compiled with a variety of options, the most fundamantal |
2551 | Libev can be compiled with a variety of options, the most fundamantal |
… | |
… | |
2449 | wants osf handles on win32 (this is the case when the select to |
2756 | wants osf handles on win32 (this is the case when the select to |
2450 | be used is the winsock select). This means that it will call |
2757 | be used is the winsock select). This means that it will call |
2451 | C<_get_osfhandle> on the fd to convert it to an OS handle. Otherwise, |
2758 | C<_get_osfhandle> on the fd to convert it to an OS handle. Otherwise, |
2452 | it is assumed that all these functions actually work on fds, even |
2759 | it is assumed that all these functions actually work on fds, even |
2453 | on win32. Should not be defined on non-win32 platforms. |
2760 | on win32. Should not be defined on non-win32 platforms. |
|
|
2761 | |
|
|
2762 | =item EV_FD_TO_WIN32_HANDLE |
|
|
2763 | |
|
|
2764 | If C<EV_SELECT_IS_WINSOCKET> is enabled, then libev needs a way to map |
|
|
2765 | file descriptors to socket handles. When not defining this symbol (the |
|
|
2766 | default), then libev will call C<_get_osfhandle>, which is usually |
|
|
2767 | correct. In some cases, programs use their own file descriptor management, |
|
|
2768 | in which case they can provide this function to map fds to socket handles. |
2454 | |
2769 | |
2455 | =item EV_USE_POLL |
2770 | =item EV_USE_POLL |
2456 | |
2771 | |
2457 | If defined to be C<1>, libev will compile in support for the C<poll>(2) |
2772 | If defined to be C<1>, libev will compile in support for the C<poll>(2) |
2458 | backend. Otherwise it will be enabled on non-win32 platforms. It |
2773 | backend. Otherwise it will be enabled on non-win32 platforms. It |
… | |
… | |
2492 | |
2807 | |
2493 | If defined to be C<1>, libev will compile in support for the Linux inotify |
2808 | If defined to be C<1>, libev will compile in support for the Linux inotify |
2494 | interface to speed up C<ev_stat> watchers. Its actual availability will |
2809 | interface to speed up C<ev_stat> watchers. Its actual availability will |
2495 | be detected at runtime. |
2810 | be detected at runtime. |
2496 | |
2811 | |
|
|
2812 | =item EV_ATOMIC_T |
|
|
2813 | |
|
|
2814 | Libev requires an integer type (suitable for storing C<0> or C<1>) whose |
|
|
2815 | access is atomic with respect to other threads or signal contexts. No such |
|
|
2816 | type is easily found in the C language, so you can provide your own type |
|
|
2817 | that you know is safe for your purposes. It is used both for signal handler "locking" |
|
|
2818 | as well as for signal and thread safety in C<ev_async> watchers. |
|
|
2819 | |
|
|
2820 | In the absense of this define, libev will use C<sig_atomic_t volatile> |
|
|
2821 | (from F<signal.h>), which is usually good enough on most platforms. |
|
|
2822 | |
2497 | =item EV_H |
2823 | =item EV_H |
2498 | |
2824 | |
2499 | The name of the F<ev.h> header file used to include it. The default if |
2825 | The name of the F<ev.h> header file used to include it. The default if |
2500 | undefined is C<"ev.h"> in F<event.h> and F<ev.c>. This can be used to |
2826 | undefined is C<"ev.h"> in F<event.h>, F<ev.c> and F<ev++.h>. This can be |
2501 | virtually rename the F<ev.h> header file in case of conflicts. |
2827 | used to virtually rename the F<ev.h> header file in case of conflicts. |
2502 | |
2828 | |
2503 | =item EV_CONFIG_H |
2829 | =item EV_CONFIG_H |
2504 | |
2830 | |
2505 | If C<EV_STANDALONE> isn't C<1>, this variable can be used to override |
2831 | If C<EV_STANDALONE> isn't C<1>, this variable can be used to override |
2506 | F<ev.c>'s idea of where to find the F<config.h> file, similarly to |
2832 | F<ev.c>'s idea of where to find the F<config.h> file, similarly to |
2507 | C<EV_H>, above. |
2833 | C<EV_H>, above. |
2508 | |
2834 | |
2509 | =item EV_EVENT_H |
2835 | =item EV_EVENT_H |
2510 | |
2836 | |
2511 | Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea |
2837 | Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea |
2512 | of how the F<event.h> header can be found, the dfeault is C<"event.h">. |
2838 | of how the F<event.h> header can be found, the default is C<"event.h">. |
2513 | |
2839 | |
2514 | =item EV_PROTOTYPES |
2840 | =item EV_PROTOTYPES |
2515 | |
2841 | |
2516 | If defined to be C<0>, then F<ev.h> will not define any function |
2842 | If defined to be C<0>, then F<ev.h> will not define any function |
2517 | prototypes, but still define all the structs and other symbols. This is |
2843 | prototypes, but still define all the structs and other symbols. This is |
… | |
… | |
2566 | defined to be C<0>, then they are not. |
2892 | defined to be C<0>, then they are not. |
2567 | |
2893 | |
2568 | =item EV_FORK_ENABLE |
2894 | =item EV_FORK_ENABLE |
2569 | |
2895 | |
2570 | If undefined or defined to be C<1>, then fork watchers are supported. If |
2896 | If undefined or defined to be C<1>, then fork watchers are supported. If |
|
|
2897 | defined to be C<0>, then they are not. |
|
|
2898 | |
|
|
2899 | =item EV_ASYNC_ENABLE |
|
|
2900 | |
|
|
2901 | If undefined or defined to be C<1>, then async watchers are supported. If |
2571 | defined to be C<0>, then they are not. |
2902 | defined to be C<0>, then they are not. |
2572 | |
2903 | |
2573 | =item EV_MINIMAL |
2904 | =item EV_MINIMAL |
2574 | |
2905 | |
2575 | If you need to shave off some kilobytes of code at the expense of some |
2906 | If you need to shave off some kilobytes of code at the expense of some |
… | |
… | |
2696 | =item Changing timer/periodic watchers (by autorepeat or calling again): O(log skipped_other_timers) |
3027 | =item Changing timer/periodic watchers (by autorepeat or calling again): O(log skipped_other_timers) |
2697 | |
3028 | |
2698 | That means that changing a timer costs less than removing/adding them |
3029 | That means that changing a timer costs less than removing/adding them |
2699 | as only the relative motion in the event queue has to be paid for. |
3030 | as only the relative motion in the event queue has to be paid for. |
2700 | |
3031 | |
2701 | =item Starting io/check/prepare/idle/signal/child watchers: O(1) |
3032 | =item Starting io/check/prepare/idle/signal/child/fork/async watchers: O(1) |
2702 | |
3033 | |
2703 | These just add the watcher into an array or at the head of a list. |
3034 | These just add the watcher into an array or at the head of a list. |
2704 | |
3035 | |
2705 | =item Stopping check/prepare/idle watchers: O(1) |
3036 | =item Stopping check/prepare/idle/fork/async watchers: O(1) |
2706 | |
3037 | |
2707 | =item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE)) |
3038 | =item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE)) |
2708 | |
3039 | |
2709 | These watchers are stored in lists then need to be walked to find the |
3040 | These watchers are stored in lists then need to be walked to find the |
2710 | correct watcher to remove. The lists are usually short (you don't usually |
3041 | correct watcher to remove. The lists are usually short (you don't usually |
… | |
… | |
2726 | =item Priority handling: O(number_of_priorities) |
3057 | =item Priority handling: O(number_of_priorities) |
2727 | |
3058 | |
2728 | Priorities are implemented by allocating some space for each |
3059 | Priorities are implemented by allocating some space for each |
2729 | priority. When doing priority-based operations, libev usually has to |
3060 | priority. When doing priority-based operations, libev usually has to |
2730 | linearly search all the priorities, but starting/stopping and activating |
3061 | linearly search all the priorities, but starting/stopping and activating |
2731 | watchers becomes O(1) w.r.t. prioritiy handling. |
3062 | watchers becomes O(1) w.r.t. priority handling. |
|
|
3063 | |
|
|
3064 | =item Sending an ev_async: O(1) |
|
|
3065 | |
|
|
3066 | =item Processing ev_async_send: O(number_of_async_watchers) |
|
|
3067 | |
|
|
3068 | =item Processing signals: O(max_signal_number) |
|
|
3069 | |
|
|
3070 | Sending involves a syscall I<iff> there were no other C<ev_async_send> |
|
|
3071 | calls in the current loop iteration. Checking for async and signal events |
|
|
3072 | involves iterating over all running async watchers or all signal numbers. |
2732 | |
3073 | |
2733 | =back |
3074 | =back |
2734 | |
3075 | |
2735 | |
3076 | |
|
|
3077 | =head1 Win32 platform limitations and workarounds |
|
|
3078 | |
|
|
3079 | Win32 doesn't support any of the standards (e.g. POSIX) that libev |
|
|
3080 | requires, and its I/O model is fundamentally incompatible with the POSIX |
|
|
3081 | model. Libev still offers limited functionality on this platform in |
|
|
3082 | the form of the C<EVBACKEND_SELECT> backend, and only supports socket |
|
|
3083 | descriptors. This only applies when using Win32 natively, not when using |
|
|
3084 | e.g. cygwin. |
|
|
3085 | |
|
|
3086 | There is no supported compilation method available on windows except |
|
|
3087 | embedding it into other applications. |
|
|
3088 | |
|
|
3089 | Due to the many, low, and arbitrary limits on the win32 platform and the |
|
|
3090 | abysmal performance of winsockets, using a large number of sockets is not |
|
|
3091 | recommended (and not reasonable). If your program needs to use more than |
|
|
3092 | a hundred or so sockets, then likely it needs to use a totally different |
|
|
3093 | implementation for windows, as libev offers the POSIX model, which cannot |
|
|
3094 | be implemented efficiently on windows (microsoft monopoly games). |
|
|
3095 | |
|
|
3096 | =over 4 |
|
|
3097 | |
|
|
3098 | =item The winsocket select function |
|
|
3099 | |
|
|
3100 | The winsocket C<select> function doesn't follow POSIX in that it requires |
|
|
3101 | socket I<handles> and not socket I<file descriptors>. This makes select |
|
|
3102 | very inefficient, and also requires a mapping from file descriptors |
|
|
3103 | to socket handles. See the discussion of the C<EV_SELECT_USE_FD_SET>, |
|
|
3104 | C<EV_SELECT_IS_WINSOCKET> and C<EV_FD_TO_WIN32_HANDLE> preprocessor |
|
|
3105 | symbols for more info. |
|
|
3106 | |
|
|
3107 | The configuration for a "naked" win32 using the microsoft runtime |
|
|
3108 | libraries and raw winsocket select is: |
|
|
3109 | |
|
|
3110 | #define EV_USE_SELECT 1 |
|
|
3111 | #define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */ |
|
|
3112 | |
|
|
3113 | Note that winsockets handling of fd sets is O(n), so you can easily get a |
|
|
3114 | complexity in the O(n²) range when using win32. |
|
|
3115 | |
|
|
3116 | =item Limited number of file descriptors |
|
|
3117 | |
|
|
3118 | Windows has numerous arbitrary (and low) limits on things. Early versions |
|
|
3119 | of winsocket's select only supported waiting for a max. of C<64> handles |
|
|
3120 | (probably owning to the fact that all windows kernels can only wait for |
|
|
3121 | C<64> things at the same time internally; microsoft recommends spawning a |
|
|
3122 | chain of threads and wait for 63 handles and the previous thread in each). |
|
|
3123 | |
|
|
3124 | Newer versions support more handles, but you need to define C<FD_SETSIZE> |
|
|
3125 | to some high number (e.g. C<2048>) before compiling the winsocket select |
|
|
3126 | call (which might be in libev or elsewhere, for example, perl does its own |
|
|
3127 | select emulation on windows). |
|
|
3128 | |
|
|
3129 | Another limit is the number of file descriptors in the microsoft runtime |
|
|
3130 | libraries, which by default is C<64> (there must be a hidden I<64> fetish |
|
|
3131 | or something like this inside microsoft). You can increase this by calling |
|
|
3132 | C<_setmaxstdio>, which can increase this limit to C<2048> (another |
|
|
3133 | arbitrary limit), but is broken in many versions of the microsoft runtime |
|
|
3134 | libraries. |
|
|
3135 | |
|
|
3136 | This might get you to about C<512> or C<2048> sockets (depending on |
|
|
3137 | windows version and/or the phase of the moon). To get more, you need to |
|
|
3138 | wrap all I/O functions and provide your own fd management, but the cost of |
|
|
3139 | calling select (O(n²)) will likely make this unworkable. |
|
|
3140 | |
|
|
3141 | =back |
|
|
3142 | |
|
|
3143 | |
2736 | =head1 AUTHOR |
3144 | =head1 AUTHOR |
2737 | |
3145 | |
2738 | Marc Lehmann <libev@schmorp.de>. |
3146 | Marc Lehmann <libev@schmorp.de>. |
2739 | |
3147 | |