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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>), the Linux C<inotify> interface |
29 | events (related to SIGCHLD), and event watchers dealing with the event |
71 | (for C<ev_stat>), relative timers (C<ev_timer>), absolute timers |
30 | loop mechanism itself (idle, prepare and check watchers). It also is quite |
72 | with customised rescheduling (C<ev_periodic>), synchronous signals |
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73 | (C<ev_signal>), process status change events (C<ev_child>), and event |
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74 | watchers dealing with the event loop mechanism itself (C<ev_idle>, |
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75 | C<ev_embed>, C<ev_prepare> and C<ev_check> watchers) as well as |
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76 | file watchers (C<ev_stat>) and even limited support for fork events |
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77 | (C<ev_fork>). |
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78 | |
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79 | It also is quite fast (see this |
31 | fast (see this L<benchmark|http://libev.schmorp.de/bench.html> comparing |
80 | L<benchmark|http://libev.schmorp.de/bench.html> comparing it to libevent |
32 | it to libevent for example). |
81 | for example). |
33 | |
82 | |
34 | =head1 CONVENTIONS |
83 | =head1 CONVENTIONS |
35 | |
84 | |
36 | Libev is very configurable. In this manual the default configuration |
85 | Libev is very configurable. In this manual the default configuration will |
37 | will be described, which supports multiple event loops. For more info |
86 | be described, which supports multiple event loops. For more info about |
38 | about various configuration options please have a look at the file |
87 | 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 |
88 | this manual. If libev was configured without support for multiple event |
40 | support for multiple event loops, then all functions taking an initial |
89 | 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 *>) |
90 | (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 | |
91 | |
44 | =head1 TIME REPRESENTATION |
92 | =head1 TIME REPRESENTATION |
45 | |
93 | |
46 | Libev represents time as a single floating point number, representing the |
94 | Libev represents time as a single floating point number, representing the |
47 | (fractional) number of seconds since the (POSIX) epoch (somewhere near |
95 | (fractional) number of seconds since the (POSIX) epoch (somewhere near |
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76 | Usually, it's a good idea to terminate if the major versions mismatch, |
124 | Usually, it's a good idea to terminate if the major versions mismatch, |
77 | as this indicates an incompatible change. Minor versions are usually |
125 | as this indicates an incompatible change. Minor versions are usually |
78 | compatible to older versions, so a larger minor version alone is usually |
126 | compatible to older versions, so a larger minor version alone is usually |
79 | not a problem. |
127 | not a problem. |
80 | |
128 | |
81 | Example: make sure we haven't accidentally been linked against the wrong |
129 | Example: Make sure we haven't accidentally been linked against the wrong |
82 | version: |
130 | version. |
83 | |
131 | |
84 | assert (("libev version mismatch", |
132 | assert (("libev version mismatch", |
85 | ev_version_major () == EV_VERSION_MAJOR |
133 | ev_version_major () == EV_VERSION_MAJOR |
86 | && ev_version_minor () >= EV_VERSION_MINOR)); |
134 | && ev_version_minor () >= EV_VERSION_MINOR)); |
87 | |
135 | |
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115 | C<ev_embeddable_backends () & ev_supported_backends ()>, likewise for |
163 | C<ev_embeddable_backends () & ev_supported_backends ()>, likewise for |
116 | recommended ones. |
164 | recommended ones. |
117 | |
165 | |
118 | See the description of C<ev_embed> watchers for more info. |
166 | See the description of C<ev_embed> watchers for more info. |
119 | |
167 | |
120 | =item ev_set_allocator (void *(*cb)(void *ptr, size_t size)) |
168 | =item ev_set_allocator (void *(*cb)(void *ptr, long size)) |
121 | |
169 | |
122 | Sets the allocation function to use (the prototype and semantics are |
170 | Sets the allocation function to use (the prototype is similar - the |
123 | identical to the realloc C function). It is used to allocate and free |
171 | semantics is identical - to the realloc C function). It is used to |
124 | memory (no surprises here). If it returns zero when memory needs to be |
172 | allocate and free memory (no surprises here). If it returns zero when |
125 | allocated, the library might abort or take some potentially destructive |
173 | memory needs to be allocated, the library might abort or take some |
126 | action. The default is your system realloc function. |
174 | potentially destructive action. The default is your system realloc |
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175 | function. |
127 | |
176 | |
128 | You could override this function in high-availability programs to, say, |
177 | You could override this function in high-availability programs to, say, |
129 | free some memory if it cannot allocate memory, to use a special allocator, |
178 | free some memory if it cannot allocate memory, to use a special allocator, |
130 | or even to sleep a while and retry until some memory is available. |
179 | or even to sleep a while and retry until some memory is available. |
131 | |
180 | |
132 | Example: replace the libev allocator with one that waits a bit and then |
181 | Example: Replace the libev allocator with one that waits a bit and then |
133 | retries: better than mine). |
182 | retries). |
134 | |
183 | |
135 | static void * |
184 | static void * |
136 | persistent_realloc (void *ptr, size_t size) |
185 | persistent_realloc (void *ptr, size_t size) |
137 | { |
186 | { |
138 | for (;;) |
187 | for (;;) |
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157 | callback is set, then libev will expect it to remedy the sitution, no |
206 | callback is set, then libev will expect it to remedy the sitution, no |
158 | matter what, when it returns. That is, libev will generally retry the |
207 | matter what, when it returns. That is, libev will generally retry the |
159 | requested operation, or, if the condition doesn't go away, do bad stuff |
208 | requested operation, or, if the condition doesn't go away, do bad stuff |
160 | (such as abort). |
209 | (such as abort). |
161 | |
210 | |
162 | Example: do the same thing as libev does internally: |
211 | Example: This is basically the same thing that libev does internally, too. |
163 | |
212 | |
164 | static void |
213 | static void |
165 | fatal_error (const char *msg) |
214 | fatal_error (const char *msg) |
166 | { |
215 | { |
167 | perror (msg); |
216 | perror (msg); |
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217 | C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will |
266 | C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will |
218 | override the flags completely if it is found in the environment. This is |
267 | override the flags completely if it is found in the environment. This is |
219 | useful to try out specific backends to test their performance, or to work |
268 | useful to try out specific backends to test their performance, or to work |
220 | around bugs. |
269 | around bugs. |
221 | |
270 | |
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271 | =item C<EVFLAG_FORKCHECK> |
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272 | |
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273 | Instead of calling C<ev_default_fork> or C<ev_loop_fork> manually after |
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274 | a fork, you can also make libev check for a fork in each iteration by |
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275 | enabling this flag. |
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276 | |
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277 | This works by calling C<getpid ()> on every iteration of the loop, |
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278 | and thus this might slow down your event loop if you do a lot of loop |
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279 | iterations and little real work, but is usually not noticable (on my |
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280 | Linux system for example, C<getpid> is actually a simple 5-insn sequence |
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281 | without a syscall and thus I<very> fast, but my Linux system also has |
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282 | C<pthread_atfork> which is even faster). |
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283 | |
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284 | The big advantage of this flag is that you can forget about fork (and |
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285 | forget about forgetting to tell libev about forking) when you use this |
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286 | flag. |
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287 | |
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288 | This flag setting cannot be overriden or specified in the C<LIBEV_FLAGS> |
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289 | environment variable. |
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290 | |
222 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
291 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
223 | |
292 | |
224 | This is your standard select(2) backend. Not I<completely> standard, as |
293 | This is your standard select(2) backend. Not I<completely> standard, as |
225 | libev tries to roll its own fd_set with no limits on the number of fds, |
294 | libev tries to roll its own fd_set with no limits on the number of fds, |
226 | but if that fails, expect a fairly low limit on the number of fds when |
295 | but if that fails, expect a fairly low limit on the number of fds when |
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313 | Similar to C<ev_default_loop>, but always creates a new event loop that is |
382 | Similar to C<ev_default_loop>, but always creates a new event loop that is |
314 | always distinct from the default loop. Unlike the default loop, it cannot |
383 | always distinct from the default loop. Unlike the default loop, it cannot |
315 | handle signal and child watchers, and attempts to do so will be greeted by |
384 | handle signal and child watchers, and attempts to do so will be greeted by |
316 | undefined behaviour (or a failed assertion if assertions are enabled). |
385 | undefined behaviour (or a failed assertion if assertions are enabled). |
317 | |
386 | |
318 | Example: try to create a event loop that uses epoll and nothing else. |
387 | Example: Try to create a event loop that uses epoll and nothing else. |
319 | |
388 | |
320 | struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); |
389 | struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); |
321 | if (!epoller) |
390 | if (!epoller) |
322 | fatal ("no epoll found here, maybe it hides under your chair"); |
391 | fatal ("no epoll found here, maybe it hides under your chair"); |
323 | |
392 | |
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422 | Signals and child watchers are implemented as I/O watchers, and will |
491 | Signals and child watchers are implemented as I/O watchers, and will |
423 | be handled here by queueing them when their watcher gets executed. |
492 | be handled here by queueing them when their watcher gets executed. |
424 | - If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
493 | - If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
425 | were used, return, otherwise continue with step *. |
494 | were used, return, otherwise continue with step *. |
426 | |
495 | |
427 | Example: queue some jobs and then loop until no events are outsanding |
496 | Example: Queue some jobs and then loop until no events are outsanding |
428 | anymore. |
497 | anymore. |
429 | |
498 | |
430 | ... queue jobs here, make sure they register event watchers as long |
499 | ... queue jobs here, make sure they register event watchers as long |
431 | ... as they still have work to do (even an idle watcher will do..) |
500 | ... as they still have work to do (even an idle watcher will do..) |
432 | ev_loop (my_loop, 0); |
501 | ev_loop (my_loop, 0); |
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452 | visible to the libev user and should not keep C<ev_loop> from exiting if |
521 | visible to the libev user and should not keep C<ev_loop> from exiting if |
453 | no event watchers registered by it are active. It is also an excellent |
522 | no event watchers registered by it are active. It is also an excellent |
454 | way to do this for generic recurring timers or from within third-party |
523 | way to do this for generic recurring timers or from within third-party |
455 | libraries. Just remember to I<unref after start> and I<ref before stop>. |
524 | libraries. Just remember to I<unref after start> and I<ref before stop>. |
456 | |
525 | |
457 | Example: create a signal watcher, but keep it from keeping C<ev_loop> |
526 | Example: Create a signal watcher, but keep it from keeping C<ev_loop> |
458 | running when nothing else is active. |
527 | running when nothing else is active. |
459 | |
528 | |
460 | struct dv_signal exitsig; |
529 | struct ev_signal exitsig; |
461 | ev_signal_init (&exitsig, sig_cb, SIGINT); |
530 | ev_signal_init (&exitsig, sig_cb, SIGINT); |
462 | ev_signal_start (myloop, &exitsig); |
531 | ev_signal_start (loop, &exitsig); |
463 | evf_unref (myloop); |
532 | evf_unref (loop); |
464 | |
533 | |
465 | Example: for some weird reason, unregister the above signal handler again. |
534 | Example: For some weird reason, unregister the above signal handler again. |
466 | |
535 | |
467 | ev_ref (myloop); |
536 | ev_ref (loop); |
468 | ev_signal_stop (myloop, &exitsig); |
537 | ev_signal_stop (loop, &exitsig); |
469 | |
538 | |
470 | =back |
539 | =back |
471 | |
540 | |
472 | |
541 | |
473 | =head1 ANATOMY OF A WATCHER |
542 | =head1 ANATOMY OF A WATCHER |
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656 | events but its callback has not yet been invoked). As long as a watcher |
725 | events but its callback has not yet been invoked). As long as a watcher |
657 | is pending (but not active) you must not call an init function on it (but |
726 | is pending (but not active) you must not call an init function on it (but |
658 | C<ev_TYPE_set> is safe) and you must make sure the watcher is available to |
727 | C<ev_TYPE_set> is safe) and you must make sure the watcher is available to |
659 | libev (e.g. you cnanot C<free ()> it). |
728 | libev (e.g. you cnanot C<free ()> it). |
660 | |
729 | |
661 | =item callback = ev_cb (ev_TYPE *watcher) |
730 | =item callback ev_cb (ev_TYPE *watcher) |
662 | |
731 | |
663 | Returns the callback currently set on the watcher. |
732 | Returns the callback currently set on the watcher. |
664 | |
733 | |
665 | =item ev_cb_set (ev_TYPE *watcher, callback) |
734 | =item ev_cb_set (ev_TYPE *watcher, callback) |
666 | |
735 | |
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694 | { |
763 | { |
695 | struct my_io *w = (struct my_io *)w_; |
764 | struct my_io *w = (struct my_io *)w_; |
696 | ... |
765 | ... |
697 | } |
766 | } |
698 | |
767 | |
699 | More interesting and less C-conformant ways of catsing your callback type |
768 | More interesting and less C-conformant ways of casting your callback type |
700 | have been omitted.... |
769 | instead have been omitted. |
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770 | |
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771 | Another common scenario is having some data structure with multiple |
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772 | watchers: |
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773 | |
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774 | struct my_biggy |
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775 | { |
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776 | int some_data; |
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777 | ev_timer t1; |
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778 | ev_timer t2; |
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779 | } |
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780 | |
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781 | In this case getting the pointer to C<my_biggy> is a bit more complicated, |
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782 | you need to use C<offsetof>: |
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783 | |
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784 | #include <stddef.h> |
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785 | |
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786 | static void |
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787 | t1_cb (EV_P_ struct ev_timer *w, int revents) |
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788 | { |
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789 | struct my_biggy big = (struct my_biggy * |
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790 | (((char *)w) - offsetof (struct my_biggy, t1)); |
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791 | } |
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792 | |
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793 | static void |
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794 | t2_cb (EV_P_ struct ev_timer *w, int revents) |
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795 | { |
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796 | struct my_biggy big = (struct my_biggy * |
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797 | (((char *)w) - offsetof (struct my_biggy, t2)); |
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798 | } |
701 | |
799 | |
702 | |
800 | |
703 | =head1 WATCHER TYPES |
801 | =head1 WATCHER TYPES |
704 | |
802 | |
705 | This section describes each watcher in detail, but will not repeat |
803 | This section describes each watcher in detail, but will not repeat |
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774 | |
872 | |
775 | The events being watched. |
873 | The events being watched. |
776 | |
874 | |
777 | =back |
875 | =back |
778 | |
876 | |
779 | Example: call C<stdin_readable_cb> when STDIN_FILENO has become, well |
877 | Example: Call C<stdin_readable_cb> when STDIN_FILENO has become, well |
780 | readable, but only once. Since it is likely line-buffered, you could |
878 | readable, but only once. Since it is likely line-buffered, you could |
781 | attempt to read a whole line in the callback: |
879 | attempt to read a whole line in the callback. |
782 | |
880 | |
783 | static void |
881 | static void |
784 | stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
882 | stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
785 | { |
883 | { |
786 | ev_io_stop (loop, w); |
884 | ev_io_stop (loop, w); |
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… | |
838 | =item ev_timer_again (loop) |
936 | =item ev_timer_again (loop) |
839 | |
937 | |
840 | This will act as if the timer timed out and restart it again if it is |
938 | This will act as if the timer timed out and restart it again if it is |
841 | repeating. The exact semantics are: |
939 | repeating. The exact semantics are: |
842 | |
940 | |
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941 | If the timer is pending, its pending status is cleared. |
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942 | |
843 | If the timer is started but nonrepeating, stop it. |
943 | If the timer is started but nonrepeating, stop it (as if it timed out). |
844 | |
944 | |
845 | If the timer is repeating, either start it if necessary (with the repeat |
945 | If the timer is repeating, either start it if necessary (with the |
846 | value), or reset the running timer to the repeat value. |
946 | C<repeat> value), or reset the running timer to the C<repeat> value. |
847 | |
947 | |
848 | This sounds a bit complicated, but here is a useful and typical |
948 | This sounds a bit complicated, but here is a useful and typical |
849 | example: Imagine you have a tcp connection and you want a so-called |
949 | example: Imagine you have a tcp connection and you want a so-called idle |
850 | idle timeout, that is, you want to be called when there have been, |
950 | timeout, that is, you want to be called when there have been, say, 60 |
851 | say, 60 seconds of inactivity on the socket. The easiest way to do |
951 | seconds of inactivity on the socket. The easiest way to do this is to |
852 | this is to configure an C<ev_timer> with C<after>=C<repeat>=C<60> and calling |
952 | configure an C<ev_timer> with a C<repeat> value of C<60> and then call |
853 | C<ev_timer_again> each time you successfully read or write some data. If |
953 | C<ev_timer_again> each time you successfully read or write some data. If |
854 | you go into an idle state where you do not expect data to travel on the |
954 | you go into an idle state where you do not expect data to travel on the |
855 | socket, you can stop the timer, and again will automatically restart it if |
955 | socket, you can C<ev_timer_stop> the timer, and C<ev_timer_again> will |
856 | need be. |
956 | automatically restart it if need be. |
857 | |
957 | |
858 | You can also ignore the C<after> value and C<ev_timer_start> altogether |
958 | That means you can ignore the C<after> value and C<ev_timer_start> |
859 | and only ever use the C<repeat> value: |
959 | altogether and only ever use the C<repeat> value and C<ev_timer_again>: |
860 | |
960 | |
861 | ev_timer_init (timer, callback, 0., 5.); |
961 | ev_timer_init (timer, callback, 0., 5.); |
862 | ev_timer_again (loop, timer); |
962 | ev_timer_again (loop, timer); |
863 | ... |
963 | ... |
864 | timer->again = 17.; |
964 | timer->again = 17.; |
865 | ev_timer_again (loop, timer); |
965 | ev_timer_again (loop, timer); |
866 | ... |
966 | ... |
867 | timer->again = 10.; |
967 | timer->again = 10.; |
868 | ev_timer_again (loop, timer); |
968 | ev_timer_again (loop, timer); |
869 | |
969 | |
870 | This is more efficient then stopping/starting the timer eahc time you want |
970 | This is more slightly efficient then stopping/starting the timer each time |
871 | to modify its timeout value. |
971 | you want to modify its timeout value. |
872 | |
972 | |
873 | =item ev_tstamp repeat [read-write] |
973 | =item ev_tstamp repeat [read-write] |
874 | |
974 | |
875 | The current C<repeat> value. Will be used each time the watcher times out |
975 | The current C<repeat> value. Will be used each time the watcher times out |
876 | or C<ev_timer_again> is called and determines the next timeout (if any), |
976 | or C<ev_timer_again> is called and determines the next timeout (if any), |
877 | which is also when any modifications are taken into account. |
977 | which is also when any modifications are taken into account. |
878 | |
978 | |
879 | =back |
979 | =back |
880 | |
980 | |
881 | Example: create a timer that fires after 60 seconds. |
981 | Example: Create a timer that fires after 60 seconds. |
882 | |
982 | |
883 | static void |
983 | static void |
884 | one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
984 | one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
885 | { |
985 | { |
886 | .. one minute over, w is actually stopped right here |
986 | .. one minute over, w is actually stopped right here |
… | |
… | |
888 | |
988 | |
889 | struct ev_timer mytimer; |
989 | struct ev_timer mytimer; |
890 | ev_timer_init (&mytimer, one_minute_cb, 60., 0.); |
990 | ev_timer_init (&mytimer, one_minute_cb, 60., 0.); |
891 | ev_timer_start (loop, &mytimer); |
991 | ev_timer_start (loop, &mytimer); |
892 | |
992 | |
893 | Example: create a timeout timer that times out after 10 seconds of |
993 | Example: Create a timeout timer that times out after 10 seconds of |
894 | inactivity. |
994 | inactivity. |
895 | |
995 | |
896 | static void |
996 | static void |
897 | timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
997 | timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
898 | { |
998 | { |
… | |
… | |
1023 | switched off. Can be changed any time, but changes only take effect when |
1123 | switched off. Can be changed any time, but changes only take effect when |
1024 | the periodic timer fires or C<ev_periodic_again> is being called. |
1124 | the periodic timer fires or C<ev_periodic_again> is being called. |
1025 | |
1125 | |
1026 | =back |
1126 | =back |
1027 | |
1127 | |
1028 | Example: call a callback every hour, or, more precisely, whenever the |
1128 | Example: Call a callback every hour, or, more precisely, whenever the |
1029 | system clock is divisible by 3600. The callback invocation times have |
1129 | system clock is divisible by 3600. The callback invocation times have |
1030 | potentially a lot of jittering, but good long-term stability. |
1130 | potentially a lot of jittering, but good long-term stability. |
1031 | |
1131 | |
1032 | static void |
1132 | static void |
1033 | clock_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
1133 | clock_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
… | |
… | |
1037 | |
1137 | |
1038 | struct ev_periodic hourly_tick; |
1138 | struct ev_periodic hourly_tick; |
1039 | ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0); |
1139 | ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0); |
1040 | ev_periodic_start (loop, &hourly_tick); |
1140 | ev_periodic_start (loop, &hourly_tick); |
1041 | |
1141 | |
1042 | Example: the same as above, but use a reschedule callback to do it: |
1142 | Example: The same as above, but use a reschedule callback to do it: |
1043 | |
1143 | |
1044 | #include <math.h> |
1144 | #include <math.h> |
1045 | |
1145 | |
1046 | static ev_tstamp |
1146 | static ev_tstamp |
1047 | my_scheduler_cb (struct ev_periodic *w, ev_tstamp now) |
1147 | my_scheduler_cb (struct ev_periodic *w, ev_tstamp now) |
… | |
… | |
1049 | return fmod (now, 3600.) + 3600.; |
1149 | return fmod (now, 3600.) + 3600.; |
1050 | } |
1150 | } |
1051 | |
1151 | |
1052 | ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb); |
1152 | ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb); |
1053 | |
1153 | |
1054 | Example: call a callback every hour, starting now: |
1154 | Example: Call a callback every hour, starting now: |
1055 | |
1155 | |
1056 | struct ev_periodic hourly_tick; |
1156 | struct ev_periodic hourly_tick; |
1057 | ev_periodic_init (&hourly_tick, clock_cb, |
1157 | ev_periodic_init (&hourly_tick, clock_cb, |
1058 | fmod (ev_now (loop), 3600.), 3600., 0); |
1158 | fmod (ev_now (loop), 3600.), 3600., 0); |
1059 | ev_periodic_start (loop, &hourly_tick); |
1159 | ev_periodic_start (loop, &hourly_tick); |
… | |
… | |
1120 | The process exit/trace status caused by C<rpid> (see your systems |
1220 | The process exit/trace status caused by C<rpid> (see your systems |
1121 | C<waitpid> and C<sys/wait.h> documentation for details). |
1221 | C<waitpid> and C<sys/wait.h> documentation for details). |
1122 | |
1222 | |
1123 | =back |
1223 | =back |
1124 | |
1224 | |
1125 | Example: try to exit cleanly on SIGINT and SIGTERM. |
1225 | Example: Try to exit cleanly on SIGINT and SIGTERM. |
1126 | |
1226 | |
1127 | static void |
1227 | static void |
1128 | sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) |
1228 | sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) |
1129 | { |
1229 | { |
1130 | ev_unloop (loop, EVUNLOOP_ALL); |
1230 | ev_unloop (loop, EVUNLOOP_ALL); |
… | |
… | |
1145 | not exist" is a status change like any other. The condition "path does |
1245 | not exist" is a status change like any other. The condition "path does |
1146 | not exist" is signified by the C<st_nlink> field being zero (which is |
1246 | not exist" is signified by the C<st_nlink> field being zero (which is |
1147 | otherwise always forced to be at least one) and all the other fields of |
1247 | otherwise always forced to be at least one) and all the other fields of |
1148 | the stat buffer having unspecified contents. |
1248 | the stat buffer having unspecified contents. |
1149 | |
1249 | |
|
|
1250 | The path I<should> be absolute and I<must not> end in a slash. If it is |
|
|
1251 | relative and your working directory changes, the behaviour is undefined. |
|
|
1252 | |
1150 | Since there is no standard to do this, the portable implementation simply |
1253 | Since there is no standard to do this, the portable implementation simply |
1151 | calls C<stat (2)> regulalry on the path to see if it changed somehow. You |
1254 | calls C<stat (2)> regularly on the path to see if it changed somehow. You |
1152 | can specify a recommended polling interval for this case. If you specify |
1255 | can specify a recommended polling interval for this case. If you specify |
1153 | a polling interval of C<0> (highly recommended!) then a I<suitable, |
1256 | a polling interval of C<0> (highly recommended!) then a I<suitable, |
1154 | unspecified default> value will be used (which you can expect to be around |
1257 | unspecified default> value will be used (which you can expect to be around |
1155 | five seconds, although this might change dynamically). Libev will also |
1258 | five seconds, although this might change dynamically). Libev will also |
1156 | impose a minimum interval which is currently around C<0.1>, but thats |
1259 | impose a minimum interval which is currently around C<0.1>, but thats |
… | |
… | |
1158 | |
1261 | |
1159 | This watcher type is not meant for massive numbers of stat watchers, |
1262 | This watcher type is not meant for massive numbers of stat watchers, |
1160 | as even with OS-supported change notifications, this can be |
1263 | as even with OS-supported change notifications, this can be |
1161 | resource-intensive. |
1264 | resource-intensive. |
1162 | |
1265 | |
1163 | At the time of this writing, no specific OS backends are implemented, but |
1266 | At the time of this writing, only the Linux inotify interface is |
1164 | if demand increases, at least a kqueue and inotify backend will be added. |
1267 | implemented (implementing kqueue support is left as an exercise for the |
|
|
1268 | reader). Inotify will be used to give hints only and should not change the |
|
|
1269 | semantics of C<ev_stat> watchers, which means that libev sometimes needs |
|
|
1270 | to fall back to regular polling again even with inotify, but changes are |
|
|
1271 | usually detected immediately, and if the file exists there will be no |
|
|
1272 | polling. |
1165 | |
1273 | |
1166 | =over 4 |
1274 | =over 4 |
1167 | |
1275 | |
1168 | =item ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval) |
1276 | =item ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval) |
1169 | |
1277 | |
… | |
… | |
1259 | kind. There is a C<ev_idle_set> macro, but using it is utterly pointless, |
1367 | kind. There is a C<ev_idle_set> macro, but using it is utterly pointless, |
1260 | believe me. |
1368 | believe me. |
1261 | |
1369 | |
1262 | =back |
1370 | =back |
1263 | |
1371 | |
1264 | Example: dynamically allocate an C<ev_idle>, start it, and in the |
1372 | Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the |
1265 | callback, free it. Alos, use no error checking, as usual. |
1373 | callback, free it. Also, use no error checking, as usual. |
1266 | |
1374 | |
1267 | static void |
1375 | static void |
1268 | idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents) |
1376 | idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents) |
1269 | { |
1377 | { |
1270 | free (w); |
1378 | free (w); |
… | |
… | |
1938 | |
2046 | |
1939 | =item EV_USE_DEVPOLL |
2047 | =item EV_USE_DEVPOLL |
1940 | |
2048 | |
1941 | reserved for future expansion, works like the USE symbols above. |
2049 | reserved for future expansion, works like the USE symbols above. |
1942 | |
2050 | |
|
|
2051 | =item EV_USE_INOTIFY |
|
|
2052 | |
|
|
2053 | If defined to be C<1>, libev will compile in support for the Linux inotify |
|
|
2054 | interface to speed up C<ev_stat> watchers. Its actual availability will |
|
|
2055 | be detected at runtime. |
|
|
2056 | |
1943 | =item EV_H |
2057 | =item EV_H |
1944 | |
2058 | |
1945 | The name of the F<ev.h> header file used to include it. The default if |
2059 | The name of the F<ev.h> header file used to include it. The default if |
1946 | undefined is C<< <ev.h> >> in F<event.h> and C<"ev.h"> in F<ev.c>. This |
2060 | undefined is C<< <ev.h> >> in F<event.h> and C<"ev.h"> in F<ev.c>. This |
1947 | can be used to virtually rename the F<ev.h> header file in case of conflicts. |
2061 | can be used to virtually rename the F<ev.h> header file in case of conflicts. |
… | |
… | |
2002 | =item EV_PID_HASHSIZE |
2116 | =item EV_PID_HASHSIZE |
2003 | |
2117 | |
2004 | C<ev_child> watchers use a small hash table to distribute workload by |
2118 | C<ev_child> watchers use a small hash table to distribute workload by |
2005 | pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more |
2119 | pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more |
2006 | than enough. If you need to manage thousands of children you might want to |
2120 | than enough. If you need to manage thousands of children you might want to |
2007 | increase this value. |
2121 | increase this value (I<must> be a power of two). |
|
|
2122 | |
|
|
2123 | =item EV_INOTIFY_HASHSIZE |
|
|
2124 | |
|
|
2125 | C<ev_staz> watchers use a small hash table to distribute workload by |
|
|
2126 | inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>), |
|
|
2127 | usually more than enough. If you need to manage thousands of C<ev_stat> |
|
|
2128 | watchers you might want to increase this value (I<must> be a power of |
|
|
2129 | two). |
2008 | |
2130 | |
2009 | =item EV_COMMON |
2131 | =item EV_COMMON |
2010 | |
2132 | |
2011 | By default, all watchers have a C<void *data> member. By redefining |
2133 | By default, all watchers have a C<void *data> member. By redefining |
2012 | this macro to a something else you can include more and other types of |
2134 | this macro to a something else you can include more and other types of |
… | |
… | |
2072 | |
2194 | |
2073 | =item Starting io/check/prepare/idle/signal/child watchers: O(1) |
2195 | =item Starting io/check/prepare/idle/signal/child watchers: O(1) |
2074 | |
2196 | |
2075 | =item Stopping check/prepare/idle watchers: O(1) |
2197 | =item Stopping check/prepare/idle watchers: O(1) |
2076 | |
2198 | |
2077 | =item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % 16)) |
2199 | =item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE)) |
2078 | |
2200 | |
2079 | =item Finding the next timer per loop iteration: O(1) |
2201 | =item Finding the next timer per loop iteration: O(1) |
2080 | |
2202 | |
2081 | =item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd) |
2203 | =item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd) |
2082 | |
2204 | |