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3 | libev - a high performance full-featured event loop written in C |
3 | libev - a high performance full-featured event loop written in C |
4 | |
4 | |
5 | =head1 SYNOPSIS |
5 | =head1 SYNOPSIS |
6 | |
6 | |
7 | #include <ev.h> |
7 | #include <ev.h> |
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8 | |
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9 | =head1 EXAMPLE PROGRAM |
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10 | |
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11 | #include <ev.h> |
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12 | |
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13 | ev_io stdin_watcher; |
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14 | ev_timer timeout_watcher; |
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15 | |
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16 | /* called when data readable on stdin */ |
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17 | static void |
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18 | stdin_cb (EV_P_ struct ev_io *w, int revents) |
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19 | { |
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20 | /* puts ("stdin ready"); */ |
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21 | ev_io_stop (EV_A_ w); /* just a syntax example */ |
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22 | ev_unloop (EV_A_ EVUNLOOP_ALL); /* leave all loop calls */ |
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23 | } |
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24 | |
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25 | static void |
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26 | timeout_cb (EV_P_ struct ev_timer *w, int revents) |
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27 | { |
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28 | /* puts ("timeout"); */ |
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29 | ev_unloop (EV_A_ EVUNLOOP_ONE); /* leave one loop call */ |
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30 | } |
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31 | |
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32 | int |
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33 | main (void) |
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34 | { |
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35 | struct ev_loop *loop = ev_default_loop (0); |
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36 | |
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37 | /* initialise an io watcher, then start it */ |
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38 | ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ); |
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39 | ev_io_start (loop, &stdin_watcher); |
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40 | |
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41 | /* simple non-repeating 5.5 second timeout */ |
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42 | ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.); |
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43 | ev_timer_start (loop, &timeout_watcher); |
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44 | |
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45 | /* loop till timeout or data ready */ |
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46 | ev_loop (loop, 0); |
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47 | |
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48 | return 0; |
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49 | } |
8 | |
50 | |
9 | =head1 DESCRIPTION |
51 | =head1 DESCRIPTION |
10 | |
52 | |
11 | Libev is an event loop: you register interest in certain events (such as a |
53 | Libev is an event loop: you register interest in certain events (such as a |
12 | file descriptor being readable or a timeout occuring), and it will manage |
54 | file descriptor being readable or a timeout occuring), and it will manage |
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21 | details of the event, and then hand it over to libev by I<starting> the |
63 | details of the event, and then hand it over to libev by I<starting> the |
22 | watcher. |
64 | watcher. |
23 | |
65 | |
24 | =head1 FEATURES |
66 | =head1 FEATURES |
25 | |
67 | |
26 | Libev supports select, poll, the linux-specific epoll and the bsd-specific |
68 | Libev supports C<select>, C<poll>, the linux-specific C<epoll>, the |
27 | kqueue mechanisms for file descriptor events, relative timers, absolute |
69 | bsd-specific C<kqueue> and the solaris-specific event port mechanisms |
28 | timers with customised rescheduling, signal events, process status change |
70 | for file descriptor events (C<ev_io>), relative timers (C<ev_timer>), |
29 | events (related to SIGCHLD), and event watchers dealing with the event |
71 | absolute timers with customised rescheduling (C<ev_periodic>), synchronous |
30 | loop mechanism itself (idle, prepare and check watchers). It also is quite |
72 | signals (C<ev_signal>), process status change events (C<ev_child>), and |
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73 | event watchers dealing with the event loop mechanism itself (C<ev_idle>, |
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74 | C<ev_embed>, C<ev_prepare> and C<ev_check> watchers) as well as |
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75 | file watchers (C<ev_stat>) and even limited support for fork events |
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76 | (C<ev_fork>). |
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77 | |
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78 | It also is quite fast (see this |
31 | fast (see this L<benchmark|http://libev.schmorp.de/bench.html> comparing |
79 | L<benchmark|http://libev.schmorp.de/bench.html> comparing it to libevent |
32 | it to libevent for example). |
80 | for example). |
33 | |
81 | |
34 | =head1 CONVENTIONS |
82 | =head1 CONVENTIONS |
35 | |
83 | |
36 | Libev is very configurable. In this manual the default configuration |
84 | Libev is very configurable. In this manual the default configuration will |
37 | will be described, which supports multiple event loops. For more info |
85 | be described, which supports multiple event loops. For more info about |
38 | about various configuration options please have a look at the file |
86 | various configuration options please have a look at B<EMBED> section in |
39 | F<README.embed> in the libev distribution. If libev was configured without |
87 | this manual. If libev was configured without support for multiple event |
40 | support for multiple event loops, then all functions taking an initial |
88 | loops, then all functions taking an initial argument of name C<loop> |
41 | argument of name C<loop> (which is always of type C<struct ev_loop *>) |
89 | (which is always of type C<struct ev_loop *>) will not have this argument. |
42 | will not have this argument. |
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43 | |
90 | |
44 | =head1 TIME REPRESENTATION |
91 | =head1 TIME REPRESENTATION |
45 | |
92 | |
46 | Libev represents time as a single floating point number, representing the |
93 | Libev represents time as a single floating point number, representing the |
47 | (fractional) number of seconds since the (POSIX) epoch (somewhere near |
94 | (fractional) number of seconds since the (POSIX) epoch (somewhere near |
48 | the beginning of 1970, details are complicated, don't ask). This type is |
95 | the beginning of 1970, details are complicated, don't ask). This type is |
49 | called C<ev_tstamp>, which is what you should use too. It usually aliases |
96 | called C<ev_tstamp>, which is what you should use too. It usually aliases |
50 | to the C<double> type in C, and when you need to do any calculations on |
97 | to the C<double> type in C, and when you need to do any calculations on |
51 | it, you should treat it as such. |
98 | it, you should treat it as such. |
52 | |
99 | |
53 | |
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54 | =head1 GLOBAL FUNCTIONS |
100 | =head1 GLOBAL FUNCTIONS |
55 | |
101 | |
56 | These functions can be called anytime, even before initialising the |
102 | These functions can be called anytime, even before initialising the |
57 | library in any way. |
103 | library in any way. |
58 | |
104 | |
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77 | Usually, it's a good idea to terminate if the major versions mismatch, |
123 | Usually, it's a good idea to terminate if the major versions mismatch, |
78 | as this indicates an incompatible change. Minor versions are usually |
124 | as this indicates an incompatible change. Minor versions are usually |
79 | compatible to older versions, so a larger minor version alone is usually |
125 | compatible to older versions, so a larger minor version alone is usually |
80 | not a problem. |
126 | not a problem. |
81 | |
127 | |
82 | Example: make sure we haven't accidentally been linked against the wrong |
128 | Example: Make sure we haven't accidentally been linked against the wrong |
83 | version: |
129 | version. |
84 | |
130 | |
85 | assert (("libev version mismatch", |
131 | assert (("libev version mismatch", |
86 | ev_version_major () == EV_VERSION_MAJOR |
132 | ev_version_major () == EV_VERSION_MAJOR |
87 | && ev_version_minor () >= EV_VERSION_MINOR)); |
133 | && ev_version_minor () >= EV_VERSION_MINOR)); |
88 | |
134 | |
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116 | C<ev_embeddable_backends () & ev_supported_backends ()>, likewise for |
162 | C<ev_embeddable_backends () & ev_supported_backends ()>, likewise for |
117 | recommended ones. |
163 | recommended ones. |
118 | |
164 | |
119 | See the description of C<ev_embed> watchers for more info. |
165 | See the description of C<ev_embed> watchers for more info. |
120 | |
166 | |
121 | =item ev_set_allocator (void *(*cb)(void *ptr, long size)) |
167 | =item ev_set_allocator (void *(*cb)(void *ptr, size_t size)) |
122 | |
168 | |
123 | Sets the allocation function to use (the prototype is similar to the |
169 | Sets the allocation function to use (the prototype and semantics are |
124 | realloc C function, the semantics are identical). It is used to allocate |
170 | identical to the realloc C function). It is used to allocate and free |
125 | and free memory (no surprises here). If it returns zero when memory |
171 | memory (no surprises here). If it returns zero when memory needs to be |
126 | needs to be allocated, the library might abort or take some potentially |
172 | allocated, the library might abort or take some potentially destructive |
127 | destructive action. The default is your system realloc function. |
173 | action. The default is your system realloc function. |
128 | |
174 | |
129 | You could override this function in high-availability programs to, say, |
175 | You could override this function in high-availability programs to, say, |
130 | free some memory if it cannot allocate memory, to use a special allocator, |
176 | free some memory if it cannot allocate memory, to use a special allocator, |
131 | or even to sleep a while and retry until some memory is available. |
177 | or even to sleep a while and retry until some memory is available. |
132 | |
178 | |
133 | Example: replace the libev allocator with one that waits a bit and then |
179 | Example: Replace the libev allocator with one that waits a bit and then |
134 | retries: better than mine). |
180 | retries). |
135 | |
181 | |
136 | static void * |
182 | static void * |
137 | persistent_realloc (void *ptr, long size) |
183 | persistent_realloc (void *ptr, size_t size) |
138 | { |
184 | { |
139 | for (;;) |
185 | for (;;) |
140 | { |
186 | { |
141 | void *newptr = realloc (ptr, size); |
187 | void *newptr = realloc (ptr, size); |
142 | |
188 | |
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158 | callback is set, then libev will expect it to remedy the sitution, no |
204 | callback is set, then libev will expect it to remedy the sitution, no |
159 | matter what, when it returns. That is, libev will generally retry the |
205 | matter what, when it returns. That is, libev will generally retry the |
160 | requested operation, or, if the condition doesn't go away, do bad stuff |
206 | requested operation, or, if the condition doesn't go away, do bad stuff |
161 | (such as abort). |
207 | (such as abort). |
162 | |
208 | |
163 | Example: do the same thing as libev does internally: |
209 | Example: This is basically the same thing that libev does internally, too. |
164 | |
210 | |
165 | static void |
211 | static void |
166 | fatal_error (const char *msg) |
212 | fatal_error (const char *msg) |
167 | { |
213 | { |
168 | perror (msg); |
214 | perror (msg); |
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314 | Similar to C<ev_default_loop>, but always creates a new event loop that is |
360 | Similar to C<ev_default_loop>, but always creates a new event loop that is |
315 | always distinct from the default loop. Unlike the default loop, it cannot |
361 | always distinct from the default loop. Unlike the default loop, it cannot |
316 | handle signal and child watchers, and attempts to do so will be greeted by |
362 | handle signal and child watchers, and attempts to do so will be greeted by |
317 | undefined behaviour (or a failed assertion if assertions are enabled). |
363 | undefined behaviour (or a failed assertion if assertions are enabled). |
318 | |
364 | |
319 | Example: try to create a event loop that uses epoll and nothing else. |
365 | Example: Try to create a event loop that uses epoll and nothing else. |
320 | |
366 | |
321 | struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); |
367 | struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); |
322 | if (!epoller) |
368 | if (!epoller) |
323 | fatal ("no epoll found here, maybe it hides under your chair"); |
369 | fatal ("no epoll found here, maybe it hides under your chair"); |
324 | |
370 | |
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423 | Signals and child watchers are implemented as I/O watchers, and will |
469 | Signals and child watchers are implemented as I/O watchers, and will |
424 | be handled here by queueing them when their watcher gets executed. |
470 | be handled here by queueing them when their watcher gets executed. |
425 | - If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
471 | - If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
426 | were used, return, otherwise continue with step *. |
472 | were used, return, otherwise continue with step *. |
427 | |
473 | |
428 | Example: queue some jobs and then loop until no events are outsanding |
474 | Example: Queue some jobs and then loop until no events are outsanding |
429 | anymore. |
475 | anymore. |
430 | |
476 | |
431 | ... queue jobs here, make sure they register event watchers as long |
477 | ... queue jobs here, make sure they register event watchers as long |
432 | ... as they still have work to do (even an idle watcher will do..) |
478 | ... as they still have work to do (even an idle watcher will do..) |
433 | ev_loop (my_loop, 0); |
479 | ev_loop (my_loop, 0); |
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453 | visible to the libev user and should not keep C<ev_loop> from exiting if |
499 | visible to the libev user and should not keep C<ev_loop> from exiting if |
454 | no event watchers registered by it are active. It is also an excellent |
500 | no event watchers registered by it are active. It is also an excellent |
455 | way to do this for generic recurring timers or from within third-party |
501 | way to do this for generic recurring timers or from within third-party |
456 | libraries. Just remember to I<unref after start> and I<ref before stop>. |
502 | libraries. Just remember to I<unref after start> and I<ref before stop>. |
457 | |
503 | |
458 | Example: create a signal watcher, but keep it from keeping C<ev_loop> |
504 | Example: Create a signal watcher, but keep it from keeping C<ev_loop> |
459 | running when nothing else is active. |
505 | running when nothing else is active. |
460 | |
506 | |
461 | struct dv_signal exitsig; |
507 | struct ev_signal exitsig; |
462 | ev_signal_init (&exitsig, sig_cb, SIGINT); |
508 | ev_signal_init (&exitsig, sig_cb, SIGINT); |
463 | ev_signal_start (myloop, &exitsig); |
509 | ev_signal_start (loop, &exitsig); |
464 | evf_unref (myloop); |
510 | evf_unref (loop); |
465 | |
511 | |
466 | Example: for some weird reason, unregister the above signal handler again. |
512 | Example: For some weird reason, unregister the above signal handler again. |
467 | |
513 | |
468 | ev_ref (myloop); |
514 | ev_ref (loop); |
469 | ev_signal_stop (myloop, &exitsig); |
515 | ev_signal_stop (loop, &exitsig); |
470 | |
516 | |
471 | =back |
517 | =back |
472 | |
518 | |
473 | |
519 | |
474 | =head1 ANATOMY OF A WATCHER |
520 | =head1 ANATOMY OF A WATCHER |
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565 | received events. Callbacks of both watcher types can start and stop as |
611 | received events. Callbacks of both watcher types can start and stop as |
566 | many watchers as they want, and all of them will be taken into account |
612 | many watchers as they want, and all of them will be taken into account |
567 | (for example, a C<ev_prepare> watcher might start an idle watcher to keep |
613 | (for example, a C<ev_prepare> watcher might start an idle watcher to keep |
568 | C<ev_loop> from blocking). |
614 | C<ev_loop> from blocking). |
569 | |
615 | |
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616 | =item C<EV_EMBED> |
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617 | |
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618 | The embedded event loop specified in the C<ev_embed> watcher needs attention. |
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619 | |
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620 | =item C<EV_FORK> |
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621 | |
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622 | The event loop has been resumed in the child process after fork (see |
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623 | C<ev_fork>). |
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624 | |
570 | =item C<EV_ERROR> |
625 | =item C<EV_ERROR> |
571 | |
626 | |
572 | An unspecified error has occured, the watcher has been stopped. This might |
627 | An unspecified error has occured, the watcher has been stopped. This might |
573 | happen because the watcher could not be properly started because libev |
628 | happen because the watcher could not be properly started because libev |
574 | ran out of memory, a file descriptor was found to be closed or any other |
629 | ran out of memory, a file descriptor was found to be closed or any other |
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648 | events but its callback has not yet been invoked). As long as a watcher |
703 | events but its callback has not yet been invoked). As long as a watcher |
649 | is pending (but not active) you must not call an init function on it (but |
704 | is pending (but not active) you must not call an init function on it (but |
650 | C<ev_TYPE_set> is safe) and you must make sure the watcher is available to |
705 | C<ev_TYPE_set> is safe) and you must make sure the watcher is available to |
651 | libev (e.g. you cnanot C<free ()> it). |
706 | libev (e.g. you cnanot C<free ()> it). |
652 | |
707 | |
653 | =item callback = ev_cb (ev_TYPE *watcher) |
708 | =item callback ev_cb (ev_TYPE *watcher) |
654 | |
709 | |
655 | Returns the callback currently set on the watcher. |
710 | Returns the callback currently set on the watcher. |
656 | |
711 | |
657 | =item ev_cb_set (ev_TYPE *watcher, callback) |
712 | =item ev_cb_set (ev_TYPE *watcher, callback) |
658 | |
713 | |
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686 | { |
741 | { |
687 | struct my_io *w = (struct my_io *)w_; |
742 | struct my_io *w = (struct my_io *)w_; |
688 | ... |
743 | ... |
689 | } |
744 | } |
690 | |
745 | |
691 | More interesting and less C-conformant ways of catsing your callback type |
746 | More interesting and less C-conformant ways of casting your callback type |
692 | have been omitted.... |
747 | instead have been omitted. |
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748 | |
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749 | Another common scenario is having some data structure with multiple |
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750 | watchers: |
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751 | |
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752 | struct my_biggy |
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753 | { |
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754 | int some_data; |
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755 | ev_timer t1; |
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756 | ev_timer t2; |
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757 | } |
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758 | |
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759 | In this case getting the pointer to C<my_biggy> is a bit more complicated, |
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760 | you need to use C<offsetof>: |
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761 | |
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762 | #include <stddef.h> |
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763 | |
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764 | static void |
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765 | t1_cb (EV_P_ struct ev_timer *w, int revents) |
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766 | { |
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767 | struct my_biggy big = (struct my_biggy * |
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768 | (((char *)w) - offsetof (struct my_biggy, t1)); |
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769 | } |
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770 | |
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771 | static void |
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772 | t2_cb (EV_P_ struct ev_timer *w, int revents) |
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773 | { |
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774 | struct my_biggy big = (struct my_biggy * |
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775 | (((char *)w) - offsetof (struct my_biggy, t2)); |
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776 | } |
693 | |
777 | |
694 | |
778 | |
695 | =head1 WATCHER TYPES |
779 | =head1 WATCHER TYPES |
696 | |
780 | |
697 | This section describes each watcher in detail, but will not repeat |
781 | This section describes each watcher in detail, but will not repeat |
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766 | |
850 | |
767 | The events being watched. |
851 | The events being watched. |
768 | |
852 | |
769 | =back |
853 | =back |
770 | |
854 | |
771 | Example: call C<stdin_readable_cb> when STDIN_FILENO has become, well |
855 | Example: Call C<stdin_readable_cb> when STDIN_FILENO has become, well |
772 | readable, but only once. Since it is likely line-buffered, you could |
856 | readable, but only once. Since it is likely line-buffered, you could |
773 | attempt to read a whole line in the callback: |
857 | attempt to read a whole line in the callback. |
774 | |
858 | |
775 | static void |
859 | static void |
776 | stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
860 | stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
777 | { |
861 | { |
778 | ev_io_stop (loop, w); |
862 | ev_io_stop (loop, w); |
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868 | or C<ev_timer_again> is called and determines the next timeout (if any), |
952 | or C<ev_timer_again> is called and determines the next timeout (if any), |
869 | which is also when any modifications are taken into account. |
953 | which is also when any modifications are taken into account. |
870 | |
954 | |
871 | =back |
955 | =back |
872 | |
956 | |
873 | Example: create a timer that fires after 60 seconds. |
957 | Example: Create a timer that fires after 60 seconds. |
874 | |
958 | |
875 | static void |
959 | static void |
876 | one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
960 | one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
877 | { |
961 | { |
878 | .. one minute over, w is actually stopped right here |
962 | .. one minute over, w is actually stopped right here |
… | |
… | |
880 | |
964 | |
881 | struct ev_timer mytimer; |
965 | struct ev_timer mytimer; |
882 | ev_timer_init (&mytimer, one_minute_cb, 60., 0.); |
966 | ev_timer_init (&mytimer, one_minute_cb, 60., 0.); |
883 | ev_timer_start (loop, &mytimer); |
967 | ev_timer_start (loop, &mytimer); |
884 | |
968 | |
885 | Example: create a timeout timer that times out after 10 seconds of |
969 | Example: Create a timeout timer that times out after 10 seconds of |
886 | inactivity. |
970 | inactivity. |
887 | |
971 | |
888 | static void |
972 | static void |
889 | timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
973 | timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
890 | { |
974 | { |
… | |
… | |
1015 | switched off. Can be changed any time, but changes only take effect when |
1099 | switched off. Can be changed any time, but changes only take effect when |
1016 | the periodic timer fires or C<ev_periodic_again> is being called. |
1100 | the periodic timer fires or C<ev_periodic_again> is being called. |
1017 | |
1101 | |
1018 | =back |
1102 | =back |
1019 | |
1103 | |
1020 | Example: call a callback every hour, or, more precisely, whenever the |
1104 | Example: Call a callback every hour, or, more precisely, whenever the |
1021 | system clock is divisible by 3600. The callback invocation times have |
1105 | system clock is divisible by 3600. The callback invocation times have |
1022 | potentially a lot of jittering, but good long-term stability. |
1106 | potentially a lot of jittering, but good long-term stability. |
1023 | |
1107 | |
1024 | static void |
1108 | static void |
1025 | clock_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
1109 | clock_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
… | |
… | |
1029 | |
1113 | |
1030 | struct ev_periodic hourly_tick; |
1114 | struct ev_periodic hourly_tick; |
1031 | ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0); |
1115 | ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0); |
1032 | ev_periodic_start (loop, &hourly_tick); |
1116 | ev_periodic_start (loop, &hourly_tick); |
1033 | |
1117 | |
1034 | Example: the same as above, but use a reschedule callback to do it: |
1118 | Example: The same as above, but use a reschedule callback to do it: |
1035 | |
1119 | |
1036 | #include <math.h> |
1120 | #include <math.h> |
1037 | |
1121 | |
1038 | static ev_tstamp |
1122 | static ev_tstamp |
1039 | my_scheduler_cb (struct ev_periodic *w, ev_tstamp now) |
1123 | my_scheduler_cb (struct ev_periodic *w, ev_tstamp now) |
… | |
… | |
1041 | return fmod (now, 3600.) + 3600.; |
1125 | return fmod (now, 3600.) + 3600.; |
1042 | } |
1126 | } |
1043 | |
1127 | |
1044 | ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb); |
1128 | ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb); |
1045 | |
1129 | |
1046 | Example: call a callback every hour, starting now: |
1130 | Example: Call a callback every hour, starting now: |
1047 | |
1131 | |
1048 | struct ev_periodic hourly_tick; |
1132 | struct ev_periodic hourly_tick; |
1049 | ev_periodic_init (&hourly_tick, clock_cb, |
1133 | ev_periodic_init (&hourly_tick, clock_cb, |
1050 | fmod (ev_now (loop), 3600.), 3600., 0); |
1134 | fmod (ev_now (loop), 3600.), 3600., 0); |
1051 | ev_periodic_start (loop, &hourly_tick); |
1135 | ev_periodic_start (loop, &hourly_tick); |
… | |
… | |
1112 | The process exit/trace status caused by C<rpid> (see your systems |
1196 | The process exit/trace status caused by C<rpid> (see your systems |
1113 | C<waitpid> and C<sys/wait.h> documentation for details). |
1197 | C<waitpid> and C<sys/wait.h> documentation for details). |
1114 | |
1198 | |
1115 | =back |
1199 | =back |
1116 | |
1200 | |
1117 | Example: try to exit cleanly on SIGINT and SIGTERM. |
1201 | Example: Try to exit cleanly on SIGINT and SIGTERM. |
1118 | |
1202 | |
1119 | static void |
1203 | static void |
1120 | sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) |
1204 | sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) |
1121 | { |
1205 | { |
1122 | ev_unloop (loop, EVUNLOOP_ALL); |
1206 | ev_unloop (loop, EVUNLOOP_ALL); |
… | |
… | |
1138 | not exist" is signified by the C<st_nlink> field being zero (which is |
1222 | not exist" is signified by the C<st_nlink> field being zero (which is |
1139 | otherwise always forced to be at least one) and all the other fields of |
1223 | otherwise always forced to be at least one) and all the other fields of |
1140 | the stat buffer having unspecified contents. |
1224 | the stat buffer having unspecified contents. |
1141 | |
1225 | |
1142 | Since there is no standard to do this, the portable implementation simply |
1226 | Since there is no standard to do this, the portable implementation simply |
1143 | calls C<stat (2)> regulalry on the path to see if it changed somehow. You |
1227 | calls C<stat (2)> regularly on the path to see if it changed somehow. You |
1144 | can specify a recommended polling interval for this case. If you specify |
1228 | can specify a recommended polling interval for this case. If you specify |
1145 | a polling interval of C<0> (highly recommended!) then a I<suitable, |
1229 | a polling interval of C<0> (highly recommended!) then a I<suitable, |
1146 | unspecified default> value will be used (which you can expect to be around |
1230 | unspecified default> value will be used (which you can expect to be around |
1147 | five seconds, although this might change dynamically). Libev will also |
1231 | five seconds, although this might change dynamically). Libev will also |
1148 | impose a minimum interval which is currently around C<0.1>, but thats |
1232 | impose a minimum interval which is currently around C<0.1>, but thats |
… | |
… | |
1150 | |
1234 | |
1151 | This watcher type is not meant for massive numbers of stat watchers, |
1235 | This watcher type is not meant for massive numbers of stat watchers, |
1152 | as even with OS-supported change notifications, this can be |
1236 | as even with OS-supported change notifications, this can be |
1153 | resource-intensive. |
1237 | resource-intensive. |
1154 | |
1238 | |
1155 | At the time of this writing, no specific OS backends are implemented, but |
1239 | At the time of this writing, only the Linux inotify interface is |
1156 | if demand increases, at least a kqueue and inotify backend will be added. |
1240 | implemented (implementing kqueue support is left as an exercise for the |
|
|
1241 | reader). Inotify will be used to give hints only and should not change the |
|
|
1242 | semantics of C<ev_stat> watchers, which means that libev sometimes needs |
|
|
1243 | to fall back to regular polling again even with inotify, but changes are |
|
|
1244 | usually detected immediately, and if the file exists there will be no |
|
|
1245 | polling. |
1157 | |
1246 | |
1158 | =over 4 |
1247 | =over 4 |
1159 | |
1248 | |
1160 | =item ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval) |
1249 | =item ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval) |
1161 | |
1250 | |
… | |
… | |
1251 | kind. There is a C<ev_idle_set> macro, but using it is utterly pointless, |
1340 | kind. There is a C<ev_idle_set> macro, but using it is utterly pointless, |
1252 | believe me. |
1341 | believe me. |
1253 | |
1342 | |
1254 | =back |
1343 | =back |
1255 | |
1344 | |
1256 | Example: dynamically allocate an C<ev_idle>, start it, and in the |
1345 | Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the |
1257 | callback, free it. Alos, use no error checking, as usual. |
1346 | callback, free it. Also, use no error checking, as usual. |
1258 | |
1347 | |
1259 | static void |
1348 | static void |
1260 | idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents) |
1349 | idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents) |
1261 | { |
1350 | { |
1262 | free (w); |
1351 | free (w); |
… | |
… | |
1470 | The embedded event loop. |
1559 | The embedded event loop. |
1471 | |
1560 | |
1472 | =back |
1561 | =back |
1473 | |
1562 | |
1474 | |
1563 | |
|
|
1564 | =head2 C<ev_fork> - the audacity to resume the event loop after a fork |
|
|
1565 | |
|
|
1566 | Fork watchers are called when a C<fork ()> was detected (usually because |
|
|
1567 | whoever is a good citizen cared to tell libev about it by calling |
|
|
1568 | C<ev_default_fork> or C<ev_loop_fork>). The invocation is done before the |
|
|
1569 | event loop blocks next and before C<ev_check> watchers are being called, |
|
|
1570 | and only in the child after the fork. If whoever good citizen calling |
|
|
1571 | C<ev_default_fork> cheats and calls it in the wrong process, the fork |
|
|
1572 | handlers will be invoked, too, of course. |
|
|
1573 | |
|
|
1574 | =over 4 |
|
|
1575 | |
|
|
1576 | =item ev_fork_init (ev_signal *, callback) |
|
|
1577 | |
|
|
1578 | Initialises and configures the fork watcher - it has no parameters of any |
|
|
1579 | kind. There is a C<ev_fork_set> macro, but using it is utterly pointless, |
|
|
1580 | believe me. |
|
|
1581 | |
|
|
1582 | =back |
|
|
1583 | |
|
|
1584 | |
1475 | =head1 OTHER FUNCTIONS |
1585 | =head1 OTHER FUNCTIONS |
1476 | |
1586 | |
1477 | There are some other functions of possible interest. Described. Here. Now. |
1587 | There are some other functions of possible interest. Described. Here. Now. |
1478 | |
1588 | |
1479 | =over 4 |
1589 | =over 4 |
… | |
… | |
1663 | : io (this, &myclass::io_cb), |
1773 | : io (this, &myclass::io_cb), |
1664 | idle (this, &myclass::idle_cb) |
1774 | idle (this, &myclass::idle_cb) |
1665 | { |
1775 | { |
1666 | io.start (fd, ev::READ); |
1776 | io.start (fd, ev::READ); |
1667 | } |
1777 | } |
|
|
1778 | |
|
|
1779 | |
|
|
1780 | =head1 MACRO MAGIC |
|
|
1781 | |
|
|
1782 | Libev can be compiled with a variety of options, the most fundemantal is |
|
|
1783 | C<EV_MULTIPLICITY>. This option determines wether (most) functions and |
|
|
1784 | callbacks have an initial C<struct ev_loop *> argument. |
|
|
1785 | |
|
|
1786 | To make it easier to write programs that cope with either variant, the |
|
|
1787 | following macros are defined: |
|
|
1788 | |
|
|
1789 | =over 4 |
|
|
1790 | |
|
|
1791 | =item C<EV_A>, C<EV_A_> |
|
|
1792 | |
|
|
1793 | This provides the loop I<argument> for functions, if one is required ("ev |
|
|
1794 | loop argument"). The C<EV_A> form is used when this is the sole argument, |
|
|
1795 | C<EV_A_> is used when other arguments are following. Example: |
|
|
1796 | |
|
|
1797 | ev_unref (EV_A); |
|
|
1798 | ev_timer_add (EV_A_ watcher); |
|
|
1799 | ev_loop (EV_A_ 0); |
|
|
1800 | |
|
|
1801 | It assumes the variable C<loop> of type C<struct ev_loop *> is in scope, |
|
|
1802 | which is often provided by the following macro. |
|
|
1803 | |
|
|
1804 | =item C<EV_P>, C<EV_P_> |
|
|
1805 | |
|
|
1806 | This provides the loop I<parameter> for functions, if one is required ("ev |
|
|
1807 | loop parameter"). The C<EV_P> form is used when this is the sole parameter, |
|
|
1808 | C<EV_P_> is used when other parameters are following. Example: |
|
|
1809 | |
|
|
1810 | // this is how ev_unref is being declared |
|
|
1811 | static void ev_unref (EV_P); |
|
|
1812 | |
|
|
1813 | // this is how you can declare your typical callback |
|
|
1814 | static void cb (EV_P_ ev_timer *w, int revents) |
|
|
1815 | |
|
|
1816 | It declares a parameter C<loop> of type C<struct ev_loop *>, quite |
|
|
1817 | suitable for use with C<EV_A>. |
|
|
1818 | |
|
|
1819 | =item C<EV_DEFAULT>, C<EV_DEFAULT_> |
|
|
1820 | |
|
|
1821 | Similar to the other two macros, this gives you the value of the default |
|
|
1822 | loop, if multiple loops are supported ("ev loop default"). |
|
|
1823 | |
|
|
1824 | =back |
|
|
1825 | |
|
|
1826 | Example: Declare and initialise a check watcher, working regardless of |
|
|
1827 | wether multiple loops are supported or not. |
|
|
1828 | |
|
|
1829 | static void |
|
|
1830 | check_cb (EV_P_ ev_timer *w, int revents) |
|
|
1831 | { |
|
|
1832 | ev_check_stop (EV_A_ w); |
|
|
1833 | } |
|
|
1834 | |
|
|
1835 | ev_check check; |
|
|
1836 | ev_check_init (&check, check_cb); |
|
|
1837 | ev_check_start (EV_DEFAULT_ &check); |
|
|
1838 | ev_loop (EV_DEFAULT_ 0); |
|
|
1839 | |
1668 | |
1840 | |
1669 | =head1 EMBEDDING |
1841 | =head1 EMBEDDING |
1670 | |
1842 | |
1671 | Libev can (and often is) directly embedded into host |
1843 | Libev can (and often is) directly embedded into host |
1672 | applications. Examples of applications that embed it include the Deliantra |
1844 | applications. Examples of applications that embed it include the Deliantra |
… | |
… | |
1847 | |
2019 | |
1848 | =item EV_USE_DEVPOLL |
2020 | =item EV_USE_DEVPOLL |
1849 | |
2021 | |
1850 | reserved for future expansion, works like the USE symbols above. |
2022 | reserved for future expansion, works like the USE symbols above. |
1851 | |
2023 | |
|
|
2024 | =item EV_USE_INOTIFY |
|
|
2025 | |
|
|
2026 | If defined to be C<1>, libev will compile in support for the Linux inotify |
|
|
2027 | interface to speed up C<ev_stat> watchers. Its actual availability will |
|
|
2028 | be detected at runtime. |
|
|
2029 | |
1852 | =item EV_H |
2030 | =item EV_H |
1853 | |
2031 | |
1854 | The name of the F<ev.h> header file used to include it. The default if |
2032 | The name of the F<ev.h> header file used to include it. The default if |
1855 | undefined is C<< <ev.h> >> in F<event.h> and C<"ev.h"> in F<ev.c>. This |
2033 | undefined is C<< <ev.h> >> in F<event.h> and C<"ev.h"> in F<ev.c>. This |
1856 | can be used to virtually rename the F<ev.h> header file in case of conflicts. |
2034 | can be used to virtually rename the F<ev.h> header file in case of conflicts. |
… | |
… | |
1895 | =item EV_STAT_ENABLE |
2073 | =item EV_STAT_ENABLE |
1896 | |
2074 | |
1897 | If undefined or defined to be C<1>, then stat watchers are supported. If |
2075 | If undefined or defined to be C<1>, then stat watchers are supported. If |
1898 | defined to be C<0>, then they are not. |
2076 | defined to be C<0>, then they are not. |
1899 | |
2077 | |
|
|
2078 | =item EV_FORK_ENABLE |
|
|
2079 | |
|
|
2080 | If undefined or defined to be C<1>, then fork watchers are supported. If |
|
|
2081 | defined to be C<0>, then they are not. |
|
|
2082 | |
1900 | =item EV_MINIMAL |
2083 | =item EV_MINIMAL |
1901 | |
2084 | |
1902 | If you need to shave off some kilobytes of code at the expense of some |
2085 | If you need to shave off some kilobytes of code at the expense of some |
1903 | speed, define this symbol to C<1>. Currently only used for gcc to override |
2086 | speed, define this symbol to C<1>. Currently only used for gcc to override |
1904 | some inlining decisions, saves roughly 30% codesize of amd64. |
2087 | some inlining decisions, saves roughly 30% codesize of amd64. |
|
|
2088 | |
|
|
2089 | =item EV_PID_HASHSIZE |
|
|
2090 | |
|
|
2091 | C<ev_child> watchers use a small hash table to distribute workload by |
|
|
2092 | pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more |
|
|
2093 | than enough. If you need to manage thousands of children you might want to |
|
|
2094 | increase this value (I<must> be a power of two). |
|
|
2095 | |
|
|
2096 | =item EV_INOTIFY_HASHSIZE |
|
|
2097 | |
|
|
2098 | C<ev_staz> watchers use a small hash table to distribute workload by |
|
|
2099 | inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>), |
|
|
2100 | usually more than enough. If you need to manage thousands of C<ev_stat> |
|
|
2101 | watchers you might want to increase this value (I<must> be a power of |
|
|
2102 | two). |
1905 | |
2103 | |
1906 | =item EV_COMMON |
2104 | =item EV_COMMON |
1907 | |
2105 | |
1908 | By default, all watchers have a C<void *data> member. By redefining |
2106 | By default, all watchers have a C<void *data> member. By redefining |
1909 | this macro to a something else you can include more and other types of |
2107 | this macro to a something else you can include more and other types of |
… | |
… | |
1969 | |
2167 | |
1970 | =item Starting io/check/prepare/idle/signal/child watchers: O(1) |
2168 | =item Starting io/check/prepare/idle/signal/child watchers: O(1) |
1971 | |
2169 | |
1972 | =item Stopping check/prepare/idle watchers: O(1) |
2170 | =item Stopping check/prepare/idle watchers: O(1) |
1973 | |
2171 | |
1974 | =item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % 16)) |
2172 | =item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE)) |
1975 | |
2173 | |
1976 | =item Finding the next timer per loop iteration: O(1) |
2174 | =item Finding the next timer per loop iteration: O(1) |
1977 | |
2175 | |
1978 | =item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd) |
2176 | =item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd) |
1979 | |
2177 | |