… | |
… | |
4 | |
4 | |
5 | =head1 SYNOPSIS |
5 | =head1 SYNOPSIS |
6 | |
6 | |
7 | #include <ev.h> |
7 | #include <ev.h> |
8 | |
8 | |
9 | =head1 EXAMPLE PROGRAM |
9 | =head2 EXAMPLE PROGRAM |
10 | |
10 | |
|
|
11 | // a single header file is required |
11 | #include <ev.h> |
12 | #include <ev.h> |
12 | |
13 | |
|
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14 | // every watcher type has its own typedef'd struct |
|
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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. |
|
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27 | ev_io_stop (EV_A_ w); |
|
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28 | |
|
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29 | // this causes all nested ev_loop's to stop iterating |
|
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30 | ev_unloop (EV_A_ EVUNLOOP_ALL); |
23 | } |
31 | } |
24 | |
32 | |
|
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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 |
|
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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 |
|
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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 | |
|
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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 | |
|
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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 |
… | |
… | |
65 | You register interest in certain events by registering so-called I<event |
79 | You register interest in certain events by registering so-called I<event |
66 | watchers>, which are relatively small C structures you initialise with the |
80 | watchers>, which are relatively small C structures you initialise with the |
67 | details of the event, and then hand it over to libev by I<starting> the |
81 | details of the event, and then hand it over to libev by I<starting> the |
68 | watcher. |
82 | watcher. |
69 | |
83 | |
70 | =head1 FEATURES |
84 | =head2 FEATURES |
71 | |
85 | |
72 | Libev supports C<select>, C<poll>, the Linux-specific C<epoll>, the |
86 | Libev supports C<select>, C<poll>, the Linux-specific C<epoll>, the |
73 | BSD-specific C<kqueue> and the Solaris-specific event port mechanisms |
87 | BSD-specific C<kqueue> and the Solaris-specific event port mechanisms |
74 | for file descriptor events (C<ev_io>), the Linux C<inotify> interface |
88 | for file descriptor events (C<ev_io>), the Linux C<inotify> interface |
75 | (for C<ev_stat>), relative timers (C<ev_timer>), absolute timers |
89 | (for C<ev_stat>), relative timers (C<ev_timer>), absolute timers |
… | |
… | |
82 | |
96 | |
83 | It also is quite fast (see this |
97 | It also is quite fast (see this |
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 | =head1 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 |
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109 | this argument. |
95 | |
110 | |
96 | =head1 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 |
100 | the beginning of 1970, details are complicated, don't ask). This type is |
115 | the beginning of 1970, details are complicated, don't ask). This type is |
101 | called C<ev_tstamp>, which is what you should use too. It usually aliases |
116 | called C<ev_tstamp>, which is what you should use too. It usually aliases |
… | |
… | |
260 | flags. If that is troubling you, check C<ev_backend ()> afterwards). |
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 | |
|
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280 | Note that this function is I<not> thread-safe, so if you want to use it |
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281 | from multiple threads, you have to lock (note also that this is unlikely, |
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282 | as loops cannot bes hared easily between threads anyway). |
|
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283 | |
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284 | The default loop is the only loop that can handle C<ev_signal> and |
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285 | C<ev_child> watchers, and to do this, it always registers a handler |
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286 | for C<SIGCHLD>. If this is a problem for your app you can either |
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287 | create a dynamic loop with C<ev_loop_new> that doesn't do that, or you |
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288 | can simply overwrite the C<SIGCHLD> signal handler I<after> calling |
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289 | C<ev_default_init>. |
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290 | |
265 | The flags argument can be used to specify special behaviour or specific |
291 | 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>). |
292 | backends to use, and is usually specified as C<0> (or C<EVFLAG_AUTO>). |
267 | |
293 | |
268 | The following flags are supported: |
294 | The following flags are supported: |
269 | |
295 | |
… | |
… | |
290 | enabling this flag. |
316 | enabling this flag. |
291 | |
317 | |
292 | This works by calling C<getpid ()> on every iteration of the loop, |
318 | 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 |
319 | 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 |
320 | 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 |
321 | 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 |
322 | without a syscall and thus I<very> fast, but my GNU/Linux system also has |
297 | C<pthread_atfork> which is even faster). |
323 | C<pthread_atfork> which is even faster). |
298 | |
324 | |
299 | The big advantage of this flag is that you can forget about fork (and |
325 | 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 |
326 | forget about forgetting to tell libev about forking) when you use this |
301 | flag. |
327 | flag. |
… | |
… | |
306 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
332 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
307 | |
333 | |
308 | This is your standard select(2) backend. Not I<completely> standard, as |
334 | This is your standard select(2) backend. Not I<completely> standard, as |
309 | libev tries to roll its own fd_set with no limits on the number of fds, |
335 | libev tries to roll its own fd_set with no limits on the number of fds, |
310 | but if that fails, expect a fairly low limit on the number of fds when |
336 | but if that fails, expect a fairly low limit on the number of fds when |
311 | using this backend. It doesn't scale too well (O(highest_fd)), but its usually |
337 | using this backend. It doesn't scale too well (O(highest_fd)), but its |
312 | the fastest backend for a low number of fds. |
338 | usually the fastest backend for a low number of (low-numbered :) fds. |
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339 | |
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340 | To get good performance out of this backend you need a high amount of |
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341 | parallelity (most of the file descriptors should be busy). If you are |
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342 | writing a server, you should C<accept ()> in a loop to accept as many |
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343 | connections as possible during one iteration. You might also want to have |
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344 | a look at C<ev_set_io_collect_interval ()> to increase the amount of |
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345 | readyness notifications you get per iteration. |
313 | |
346 | |
314 | =item C<EVBACKEND_POLL> (value 2, poll backend, available everywhere except on windows) |
347 | =item C<EVBACKEND_POLL> (value 2, poll backend, available everywhere except on windows) |
315 | |
348 | |
316 | And this is your standard poll(2) backend. It's more complicated than |
349 | And this is your standard poll(2) backend. It's more complicated |
317 | select, but handles sparse fds better and has no artificial limit on the |
350 | than select, but handles sparse fds better and has no artificial |
318 | number of fds you can use (except it will slow down considerably with a |
351 | limit on the number of fds you can use (except it will slow down |
319 | lot of inactive fds). It scales similarly to select, i.e. O(total_fds). |
352 | considerably with a lot of inactive fds). It scales similarly to select, |
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353 | i.e. O(total_fds). See the entry for C<EVBACKEND_SELECT>, above, for |
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354 | performance tips. |
320 | |
355 | |
321 | =item C<EVBACKEND_EPOLL> (value 4, Linux) |
356 | =item C<EVBACKEND_EPOLL> (value 4, Linux) |
322 | |
357 | |
323 | For few fds, this backend is a bit little slower than poll and select, |
358 | For few fds, this backend is a bit little slower than poll and select, |
324 | but it scales phenomenally better. While poll and select usually scale |
359 | but it scales phenomenally better. While poll and select usually scale |
325 | like O(total_fds) where n is the total number of fds (or the highest fd), |
360 | like O(total_fds) where n is the total number of fds (or the highest fd), |
326 | epoll scales either O(1) or O(active_fds). The epoll design has a number |
361 | epoll scales either O(1) or O(active_fds). The epoll design has a number |
327 | of shortcomings, such as silently dropping events in some hard-to-detect |
362 | of shortcomings, such as silently dropping events in some hard-to-detect |
328 | cases and rewiring a syscall per fd change, no fork support and bad |
363 | cases and rewiring a syscall per fd change, no fork support and bad |
329 | support for dup: |
364 | support for dup. |
330 | |
365 | |
331 | While stopping, setting and starting an I/O watcher in the same iteration |
366 | While stopping, setting and starting an I/O watcher in the same iteration |
332 | will result in some caching, there is still a syscall per such incident |
367 | will result in some caching, there is still a syscall per such incident |
333 | (because the fd could point to a different file description now), so its |
368 | (because the fd could point to a different file description now), so its |
334 | best to avoid that. Also, C<dup ()>'ed file descriptors might not work |
369 | best to avoid that. Also, C<dup ()>'ed file descriptors might not work |
335 | very well if you register events for both fds. |
370 | very well if you register events for both fds. |
336 | |
371 | |
337 | Please note that epoll sometimes generates spurious notifications, so you |
372 | Please note that epoll sometimes generates spurious notifications, so you |
338 | need to use non-blocking I/O or other means to avoid blocking when no data |
373 | need to use non-blocking I/O or other means to avoid blocking when no data |
339 | (or space) is available. |
374 | (or space) is available. |
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375 | |
|
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376 | Best performance from this backend is achieved by not unregistering all |
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377 | watchers for a file descriptor until it has been closed, if possible, i.e. |
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378 | keep at least one watcher active per fd at all times. |
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379 | |
|
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380 | While nominally embeddeble in other event loops, this feature is broken in |
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381 | all kernel versions tested so far. |
340 | |
382 | |
341 | =item C<EVBACKEND_KQUEUE> (value 8, most BSD clones) |
383 | =item C<EVBACKEND_KQUEUE> (value 8, most BSD clones) |
342 | |
384 | |
343 | Kqueue deserves special mention, as at the time of this writing, it |
385 | Kqueue deserves special mention, as at the time of this writing, it |
344 | was broken on all BSDs except NetBSD (usually it doesn't work reliably |
386 | was broken on all BSDs except NetBSD (usually it doesn't work reliably |
… | |
… | |
357 | course). While stopping, setting and starting an I/O watcher does never |
399 | course). While stopping, setting and starting an I/O watcher does never |
358 | cause an extra syscall as with C<EVBACKEND_EPOLL>, it still adds up to |
400 | cause an extra syscall as with C<EVBACKEND_EPOLL>, it still adds up to |
359 | two event changes per incident, support for C<fork ()> is very bad and it |
401 | two event changes per incident, support for C<fork ()> is very bad and it |
360 | drops fds silently in similarly hard-to-detect cases. |
402 | drops fds silently in similarly hard-to-detect cases. |
361 | |
403 | |
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404 | This backend usually performs well under most conditions. |
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405 | |
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406 | While nominally embeddable in other event loops, this doesn't work |
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407 | everywhere, so you might need to test for this. And since it is broken |
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408 | almost everywhere, you should only use it when you have a lot of sockets |
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409 | (for which it usually works), by embedding it into another event loop |
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410 | (e.g. C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>) and using it only for |
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411 | sockets. |
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412 | |
362 | =item C<EVBACKEND_DEVPOLL> (value 16, Solaris 8) |
413 | =item C<EVBACKEND_DEVPOLL> (value 16, Solaris 8) |
363 | |
414 | |
364 | This is not implemented yet (and might never be). |
415 | This is not implemented yet (and might never be, unless you send me an |
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416 | implementation). According to reports, C</dev/poll> only supports sockets |
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417 | and is not embeddable, which would limit the usefulness of this backend |
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418 | immensely. |
365 | |
419 | |
366 | =item C<EVBACKEND_PORT> (value 32, Solaris 10) |
420 | =item C<EVBACKEND_PORT> (value 32, Solaris 10) |
367 | |
421 | |
368 | This uses the Solaris 10 event port mechanism. As with everything on Solaris, |
422 | This uses the Solaris 10 event port mechanism. As with everything on Solaris, |
369 | it's really slow, but it still scales very well (O(active_fds)). |
423 | it's really slow, but it still scales very well (O(active_fds)). |
370 | |
424 | |
371 | Please note that solaris event ports can deliver a lot of spurious |
425 | Please note that solaris event ports can deliver a lot of spurious |
372 | notifications, so you need to use non-blocking I/O or other means to avoid |
426 | notifications, so you need to use non-blocking I/O or other means to avoid |
373 | blocking when no data (or space) is available. |
427 | blocking when no data (or space) is available. |
374 | |
428 | |
|
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429 | While this backend scales well, it requires one system call per active |
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430 | file descriptor per loop iteration. For small and medium numbers of file |
|
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431 | descriptors a "slow" C<EVBACKEND_SELECT> or C<EVBACKEND_POLL> backend |
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432 | might perform better. |
|
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433 | |
|
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434 | On the positive side, ignoring the spurious readyness notifications, this |
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435 | backend actually performed to specification in all tests and is fully |
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436 | embeddable, which is a rare feat among the OS-specific backends. |
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437 | |
375 | =item C<EVBACKEND_ALL> |
438 | =item C<EVBACKEND_ALL> |
376 | |
439 | |
377 | Try all backends (even potentially broken ones that wouldn't be tried |
440 | Try all backends (even potentially broken ones that wouldn't be tried |
378 | with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as |
441 | with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as |
379 | C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>. |
442 | C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>. |
380 | |
443 | |
|
|
444 | It is definitely not recommended to use this flag. |
|
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445 | |
381 | =back |
446 | =back |
382 | |
447 | |
383 | If one or more of these are ored into the flags value, then only these |
448 | If one or more of these are ored into the flags value, then only these |
384 | backends will be tried (in the reverse order as given here). If none are |
449 | backends will be tried (in the reverse order as listed here). If none are |
385 | specified, most compiled-in backend will be tried, usually in reverse |
450 | specified, all backends in C<ev_recommended_backends ()> will be tried. |
386 | order of their flag values :) |
|
|
387 | |
451 | |
388 | The most typical usage is like this: |
452 | The most typical usage is like this: |
389 | |
453 | |
390 | if (!ev_default_loop (0)) |
454 | if (!ev_default_loop (0)) |
391 | fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?"); |
455 | fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?"); |
… | |
… | |
405 | |
469 | |
406 | Similar to C<ev_default_loop>, but always creates a new event loop that is |
470 | Similar to C<ev_default_loop>, but always creates a new event loop that is |
407 | always distinct from the default loop. Unlike the default loop, it cannot |
471 | always distinct from the default loop. Unlike the default loop, it cannot |
408 | handle signal and child watchers, and attempts to do so will be greeted by |
472 | handle signal and child watchers, and attempts to do so will be greeted by |
409 | undefined behaviour (or a failed assertion if assertions are enabled). |
473 | undefined behaviour (or a failed assertion if assertions are enabled). |
|
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474 | |
|
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475 | Note that this function I<is> thread-safe, and the recommended way to use |
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476 | libev with threads is indeed to create one loop per thread, and using the |
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477 | default loop in the "main" or "initial" thread. |
410 | |
478 | |
411 | Example: Try to create a event loop that uses epoll and nothing else. |
479 | Example: Try to create a event loop that uses epoll and nothing else. |
412 | |
480 | |
413 | struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); |
481 | struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); |
414 | if (!epoller) |
482 | if (!epoller) |
… | |
… | |
438 | Like C<ev_default_destroy>, but destroys an event loop created by an |
506 | Like C<ev_default_destroy>, but destroys an event loop created by an |
439 | earlier call to C<ev_loop_new>. |
507 | earlier call to C<ev_loop_new>. |
440 | |
508 | |
441 | =item ev_default_fork () |
509 | =item ev_default_fork () |
442 | |
510 | |
|
|
511 | This function sets a flag that causes subsequent C<ev_loop> iterations |
443 | This function reinitialises the kernel state for backends that have |
512 | to reinitialise the kernel state for backends that have one. Despite the |
444 | one. Despite the name, you can call it anytime, but it makes most sense |
513 | name, you can call it anytime, but it makes most sense after forking, in |
445 | after forking, in either the parent or child process (or both, but that |
514 | the child process (or both child and parent, but that again makes little |
446 | again makes little sense). |
515 | sense). You I<must> call it in the child before using any of the libev |
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516 | functions, and it will only take effect at the next C<ev_loop> iteration. |
447 | |
517 | |
448 | You I<must> call this function in the child process after forking if and |
518 | On the other hand, you only need to call this function in the child |
449 | only if you want to use the event library in both processes. If you just |
519 | process if and only if you want to use the event library in the child. If |
450 | fork+exec, you don't have to call it. |
520 | you just fork+exec, you don't have to call it at all. |
451 | |
521 | |
452 | The function itself is quite fast and it's usually not a problem to call |
522 | The function itself is quite fast and it's usually not a problem to call |
453 | it just in case after a fork. To make this easy, the function will fit in |
523 | it just in case after a fork. To make this easy, the function will fit in |
454 | quite nicely into a call to C<pthread_atfork>: |
524 | quite nicely into a call to C<pthread_atfork>: |
455 | |
525 | |
456 | pthread_atfork (0, 0, ev_default_fork); |
526 | pthread_atfork (0, 0, ev_default_fork); |
457 | |
527 | |
458 | At the moment, C<EVBACKEND_SELECT> and C<EVBACKEND_POLL> are safe to use |
|
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459 | without calling this function, so if you force one of those backends you |
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460 | do not need to care. |
|
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461 | |
|
|
462 | =item ev_loop_fork (loop) |
528 | =item ev_loop_fork (loop) |
463 | |
529 | |
464 | Like C<ev_default_fork>, but acts on an event loop created by |
530 | Like C<ev_default_fork>, but acts on an event loop created by |
465 | C<ev_loop_new>. Yes, you have to call this on every allocated event loop |
531 | C<ev_loop_new>. Yes, you have to call this on every allocated event loop |
466 | after fork, and how you do this is entirely your own problem. |
532 | after fork, and how you do this is entirely your own problem. |
|
|
533 | |
|
|
534 | =item int ev_is_default_loop (loop) |
|
|
535 | |
|
|
536 | Returns true when the given loop actually is the default loop, false otherwise. |
467 | |
537 | |
468 | =item unsigned int ev_loop_count (loop) |
538 | =item unsigned int ev_loop_count (loop) |
469 | |
539 | |
470 | Returns the count of loop iterations for the loop, which is identical to |
540 | Returns the count of loop iterations for the loop, which is identical to |
471 | the number of times libev did poll for new events. It starts at C<0> and |
541 | the number of times libev did poll for new events. It starts at C<0> and |
… | |
… | |
516 | usually a better approach for this kind of thing. |
586 | usually a better approach for this kind of thing. |
517 | |
587 | |
518 | Here are the gory details of what C<ev_loop> does: |
588 | Here are the gory details of what C<ev_loop> does: |
519 | |
589 | |
520 | - Before the first iteration, call any pending watchers. |
590 | - Before the first iteration, call any pending watchers. |
521 | * If there are no active watchers (reference count is zero), return. |
591 | * If EVFLAG_FORKCHECK was used, check for a fork. |
522 | - Queue all prepare watchers and then call all outstanding watchers. |
592 | - If a fork was detected, queue and call all fork watchers. |
|
|
593 | - Queue and call all prepare watchers. |
523 | - If we have been forked, recreate the kernel state. |
594 | - If we have been forked, recreate the kernel state. |
524 | - Update the kernel state with all outstanding changes. |
595 | - Update the kernel state with all outstanding changes. |
525 | - Update the "event loop time". |
596 | - Update the "event loop time". |
526 | - Calculate for how long to block. |
597 | - Calculate for how long to sleep or block, if at all |
|
|
598 | (active idle watchers, EVLOOP_NONBLOCK or not having |
|
|
599 | any active watchers at all will result in not sleeping). |
|
|
600 | - Sleep if the I/O and timer collect interval say so. |
527 | - Block the process, waiting for any events. |
601 | - Block the process, waiting for any events. |
528 | - Queue all outstanding I/O (fd) events. |
602 | - Queue all outstanding I/O (fd) events. |
529 | - Update the "event loop time" and do time jump handling. |
603 | - Update the "event loop time" and do time jump handling. |
530 | - Queue all outstanding timers. |
604 | - Queue all outstanding timers. |
531 | - Queue all outstanding periodics. |
605 | - Queue all outstanding periodics. |
532 | - If no events are pending now, queue all idle watchers. |
606 | - If no events are pending now, queue all idle watchers. |
533 | - Queue all check watchers. |
607 | - Queue all check watchers. |
534 | - Call all queued watchers in reverse order (i.e. check watchers first). |
608 | - Call all queued watchers in reverse order (i.e. check watchers first). |
535 | Signals and child watchers are implemented as I/O watchers, and will |
609 | Signals and child watchers are implemented as I/O watchers, and will |
536 | be handled here by queueing them when their watcher gets executed. |
610 | be handled here by queueing them when their watcher gets executed. |
537 | - If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
611 | - If ev_unloop has been called, or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
538 | were used, return, otherwise continue with step *. |
612 | were used, or there are no active watchers, return, otherwise |
|
|
613 | continue with step *. |
539 | |
614 | |
540 | Example: Queue some jobs and then loop until no events are outsanding |
615 | Example: Queue some jobs and then loop until no events are outstanding |
541 | anymore. |
616 | anymore. |
542 | |
617 | |
543 | ... queue jobs here, make sure they register event watchers as long |
618 | ... queue jobs here, make sure they register event watchers as long |
544 | ... as they still have work to do (even an idle watcher will do..) |
619 | ... as they still have work to do (even an idle watcher will do..) |
545 | ev_loop (my_loop, 0); |
620 | ev_loop (my_loop, 0); |
… | |
… | |
549 | |
624 | |
550 | Can be used to make a call to C<ev_loop> return early (but only after it |
625 | Can be used to make a call to C<ev_loop> return early (but only after it |
551 | has processed all outstanding events). The C<how> argument must be either |
626 | has processed all outstanding events). The C<how> argument must be either |
552 | C<EVUNLOOP_ONE>, which will make the innermost C<ev_loop> call return, or |
627 | C<EVUNLOOP_ONE>, which will make the innermost C<ev_loop> call return, or |
553 | C<EVUNLOOP_ALL>, which will make all nested C<ev_loop> calls return. |
628 | C<EVUNLOOP_ALL>, which will make all nested C<ev_loop> calls return. |
|
|
629 | |
|
|
630 | This "unloop state" will be cleared when entering C<ev_loop> again. |
554 | |
631 | |
555 | =item ev_ref (loop) |
632 | =item ev_ref (loop) |
556 | |
633 | |
557 | =item ev_unref (loop) |
634 | =item ev_unref (loop) |
558 | |
635 | |
… | |
… | |
563 | returning, ev_unref() after starting, and ev_ref() before stopping it. For |
640 | returning, ev_unref() after starting, and ev_ref() before stopping it. For |
564 | example, libev itself uses this for its internal signal pipe: It is not |
641 | example, libev itself uses this for its internal signal pipe: It is not |
565 | visible to the libev user and should not keep C<ev_loop> from exiting if |
642 | visible to the libev user and should not keep C<ev_loop> from exiting if |
566 | no event watchers registered by it are active. It is also an excellent |
643 | no event watchers registered by it are active. It is also an excellent |
567 | way to do this for generic recurring timers or from within third-party |
644 | way to do this for generic recurring timers or from within third-party |
568 | libraries. Just remember to I<unref after start> and I<ref before stop>. |
645 | libraries. Just remember to I<unref after start> and I<ref before stop> |
|
|
646 | (but only if the watcher wasn't active before, or was active before, |
|
|
647 | respectively). |
569 | |
648 | |
570 | Example: Create a signal watcher, but keep it from keeping C<ev_loop> |
649 | Example: Create a signal watcher, but keep it from keeping C<ev_loop> |
571 | running when nothing else is active. |
650 | running when nothing else is active. |
572 | |
651 | |
573 | struct ev_signal exitsig; |
652 | struct ev_signal exitsig; |
… | |
… | |
721 | |
800 | |
722 | =item C<EV_FORK> |
801 | =item C<EV_FORK> |
723 | |
802 | |
724 | The event loop has been resumed in the child process after fork (see |
803 | The event loop has been resumed in the child process after fork (see |
725 | C<ev_fork>). |
804 | C<ev_fork>). |
|
|
805 | |
|
|
806 | =item C<EV_ASYNC> |
|
|
807 | |
|
|
808 | The given async watcher has been asynchronously notified (see C<ev_async>). |
726 | |
809 | |
727 | =item C<EV_ERROR> |
810 | =item C<EV_ERROR> |
728 | |
811 | |
729 | An unspecified error has occured, the watcher has been stopped. This might |
812 | An unspecified error has occured, the watcher has been stopped. This might |
730 | happen because the watcher could not be properly started because libev |
813 | happen because the watcher could not be properly started because libev |
… | |
… | |
948 | In general you can register as many read and/or write event watchers per |
1031 | In general you can register as many read and/or write event watchers per |
949 | fd as you want (as long as you don't confuse yourself). Setting all file |
1032 | fd as you want (as long as you don't confuse yourself). Setting all file |
950 | descriptors to non-blocking mode is also usually a good idea (but not |
1033 | descriptors to non-blocking mode is also usually a good idea (but not |
951 | required if you know what you are doing). |
1034 | required if you know what you are doing). |
952 | |
1035 | |
953 | You have to be careful with dup'ed file descriptors, though. Some backends |
|
|
954 | (the linux epoll backend is a notable example) cannot handle dup'ed file |
|
|
955 | descriptors correctly if you register interest in two or more fds pointing |
|
|
956 | to the same underlying file/socket/etc. description (that is, they share |
|
|
957 | the same underlying "file open"). |
|
|
958 | |
|
|
959 | If you must do this, then force the use of a known-to-be-good backend |
1036 | If you must do this, then force the use of a known-to-be-good backend |
960 | (at the time of this writing, this includes only C<EVBACKEND_SELECT> and |
1037 | (at the time of this writing, this includes only C<EVBACKEND_SELECT> and |
961 | C<EVBACKEND_POLL>). |
1038 | C<EVBACKEND_POLL>). |
962 | |
1039 | |
963 | Another thing you have to watch out for is that it is quite easy to |
1040 | Another thing you have to watch out for is that it is quite easy to |
… | |
… | |
997 | optimisations to libev. |
1074 | optimisations to libev. |
998 | |
1075 | |
999 | =head3 The special problem of dup'ed file descriptors |
1076 | =head3 The special problem of dup'ed file descriptors |
1000 | |
1077 | |
1001 | Some backends (e.g. epoll), cannot register events for file descriptors, |
1078 | Some backends (e.g. epoll), cannot register events for file descriptors, |
1002 | but only events for the underlying file descriptions. That menas when you |
1079 | but only events for the underlying file descriptions. That means when you |
1003 | have C<dup ()>'ed file descriptors and register events for them, only one |
1080 | have C<dup ()>'ed file descriptors or weirder constellations, and register |
1004 | file descriptor might actually receive events. |
1081 | events for them, only one file descriptor might actually receive events. |
1005 | |
1082 | |
1006 | There is no workaorund possible except not registering events |
1083 | There is no workaround possible except not registering events |
1007 | for potentially C<dup ()>'ed file descriptors or to resort to |
1084 | for potentially C<dup ()>'ed file descriptors, or to resort to |
1008 | C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>. |
1085 | C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>. |
1009 | |
1086 | |
1010 | =head3 The special problem of fork |
1087 | =head3 The special problem of fork |
1011 | |
1088 | |
1012 | Some backends (epoll, kqueue) do not support C<fork ()> at all or exhibit |
1089 | Some backends (epoll, kqueue) do not support C<fork ()> at all or exhibit |
… | |
… | |
1016 | To support fork in your programs, you either have to call |
1093 | To support fork in your programs, you either have to call |
1017 | C<ev_default_fork ()> or C<ev_loop_fork ()> after a fork in the child, |
1094 | C<ev_default_fork ()> or C<ev_loop_fork ()> after a fork in the child, |
1018 | enable C<EVFLAG_FORKCHECK>, or resort to C<EVBACKEND_SELECT> or |
1095 | enable C<EVFLAG_FORKCHECK>, or resort to C<EVBACKEND_SELECT> or |
1019 | C<EVBACKEND_POLL>. |
1096 | C<EVBACKEND_POLL>. |
1020 | |
1097 | |
|
|
1098 | =head3 The special problem of SIGPIPE |
|
|
1099 | |
|
|
1100 | While not really specific to libev, it is easy to forget about SIGPIPE: |
|
|
1101 | when reading from a pipe whose other end has been closed, your program |
|
|
1102 | gets send a SIGPIPE, which, by default, aborts your program. For most |
|
|
1103 | programs this is sensible behaviour, for daemons, this is usually |
|
|
1104 | undesirable. |
|
|
1105 | |
|
|
1106 | So when you encounter spurious, unexplained daemon exits, make sure you |
|
|
1107 | ignore SIGPIPE (and maybe make sure you log the exit status of your daemon |
|
|
1108 | somewhere, as that would have given you a big clue). |
|
|
1109 | |
1021 | |
1110 | |
1022 | =head3 Watcher-Specific Functions |
1111 | =head3 Watcher-Specific Functions |
1023 | |
1112 | |
1024 | =over 4 |
1113 | =over 4 |
1025 | |
1114 | |
… | |
… | |
1038 | =item int events [read-only] |
1127 | =item int events [read-only] |
1039 | |
1128 | |
1040 | The events being watched. |
1129 | The events being watched. |
1041 | |
1130 | |
1042 | =back |
1131 | =back |
|
|
1132 | |
|
|
1133 | =head3 Examples |
1043 | |
1134 | |
1044 | Example: Call C<stdin_readable_cb> when STDIN_FILENO has become, well |
1135 | Example: Call C<stdin_readable_cb> when STDIN_FILENO has become, well |
1045 | readable, but only once. Since it is likely line-buffered, you could |
1136 | readable, but only once. Since it is likely line-buffered, you could |
1046 | attempt to read a whole line in the callback. |
1137 | attempt to read a whole line in the callback. |
1047 | |
1138 | |
… | |
… | |
1100 | configure a timer to trigger every 10 seconds, then it will trigger at |
1191 | configure a timer to trigger every 10 seconds, then it will trigger at |
1101 | exactly 10 second intervals. If, however, your program cannot keep up with |
1192 | exactly 10 second intervals. If, however, your program cannot keep up with |
1102 | the timer (because it takes longer than those 10 seconds to do stuff) the |
1193 | the timer (because it takes longer than those 10 seconds to do stuff) the |
1103 | timer will not fire more than once per event loop iteration. |
1194 | timer will not fire more than once per event loop iteration. |
1104 | |
1195 | |
1105 | =item ev_timer_again (loop) |
1196 | =item ev_timer_again (loop, ev_timer *) |
1106 | |
1197 | |
1107 | This will act as if the timer timed out and restart it again if it is |
1198 | This will act as if the timer timed out and restart it again if it is |
1108 | repeating. The exact semantics are: |
1199 | repeating. The exact semantics are: |
1109 | |
1200 | |
1110 | If the timer is pending, its pending status is cleared. |
1201 | If the timer is pending, its pending status is cleared. |
… | |
… | |
1145 | or C<ev_timer_again> is called and determines the next timeout (if any), |
1236 | or C<ev_timer_again> is called and determines the next timeout (if any), |
1146 | which is also when any modifications are taken into account. |
1237 | which is also when any modifications are taken into account. |
1147 | |
1238 | |
1148 | =back |
1239 | =back |
1149 | |
1240 | |
|
|
1241 | =head3 Examples |
|
|
1242 | |
1150 | Example: Create a timer that fires after 60 seconds. |
1243 | Example: Create a timer that fires after 60 seconds. |
1151 | |
1244 | |
1152 | static void |
1245 | static void |
1153 | one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
1246 | one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
1154 | { |
1247 | { |
… | |
… | |
1217 | In this configuration the watcher triggers an event at the wallclock time |
1310 | In this configuration the watcher triggers an event at the wallclock time |
1218 | C<at> and doesn't repeat. It will not adjust when a time jump occurs, |
1311 | C<at> and doesn't repeat. It will not adjust when a time jump occurs, |
1219 | that is, if it is to be run at January 1st 2011 then it will run when the |
1312 | that is, if it is to be run at January 1st 2011 then it will run when the |
1220 | system time reaches or surpasses this time. |
1313 | system time reaches or surpasses this time. |
1221 | |
1314 | |
1222 | =item * non-repeating interval timer (at = offset, interval > 0, reschedule_cb = 0) |
1315 | =item * repeating interval timer (at = offset, interval > 0, reschedule_cb = 0) |
1223 | |
1316 | |
1224 | In this mode the watcher will always be scheduled to time out at the next |
1317 | In this mode the watcher will always be scheduled to time out at the next |
1225 | C<at + N * interval> time (for some integer N, which can also be negative) |
1318 | C<at + N * interval> time (for some integer N, which can also be negative) |
1226 | and then repeat, regardless of any time jumps. |
1319 | and then repeat, regardless of any time jumps. |
1227 | |
1320 | |
… | |
… | |
1310 | |
1403 | |
1311 | When active, contains the absolute time that the watcher is supposed to |
1404 | When active, contains the absolute time that the watcher is supposed to |
1312 | trigger next. |
1405 | trigger next. |
1313 | |
1406 | |
1314 | =back |
1407 | =back |
|
|
1408 | |
|
|
1409 | =head3 Examples |
1315 | |
1410 | |
1316 | Example: Call a callback every hour, or, more precisely, whenever the |
1411 | Example: Call a callback every hour, or, more precisely, whenever the |
1317 | system clock is divisible by 3600. The callback invocation times have |
1412 | system clock is divisible by 3600. The callback invocation times have |
1318 | potentially a lot of jittering, but good long-term stability. |
1413 | potentially a lot of jittering, but good long-term stability. |
1319 | |
1414 | |
… | |
… | |
1359 | with the kernel (thus it coexists with your own signal handlers as long |
1454 | with the kernel (thus it coexists with your own signal handlers as long |
1360 | as you don't register any with libev). Similarly, when the last signal |
1455 | as you don't register any with libev). Similarly, when the last signal |
1361 | watcher for a signal is stopped libev will reset the signal handler to |
1456 | watcher for a signal is stopped libev will reset the signal handler to |
1362 | SIG_DFL (regardless of what it was set to before). |
1457 | SIG_DFL (regardless of what it was set to before). |
1363 | |
1458 | |
|
|
1459 | If possible and supported, libev will install its handlers with |
|
|
1460 | C<SA_RESTART> behaviour enabled, so syscalls should not be unduly |
|
|
1461 | interrupted. If you have a problem with syscalls getting interrupted by |
|
|
1462 | signals you can block all signals in an C<ev_check> watcher and unblock |
|
|
1463 | them in an C<ev_prepare> watcher. |
|
|
1464 | |
1364 | =head3 Watcher-Specific Functions and Data Members |
1465 | =head3 Watcher-Specific Functions and Data Members |
1365 | |
1466 | |
1366 | =over 4 |
1467 | =over 4 |
1367 | |
1468 | |
1368 | =item ev_signal_init (ev_signal *, callback, int signum) |
1469 | =item ev_signal_init (ev_signal *, callback, int signum) |
… | |
… | |
1376 | |
1477 | |
1377 | The signal the watcher watches out for. |
1478 | The signal the watcher watches out for. |
1378 | |
1479 | |
1379 | =back |
1480 | =back |
1380 | |
1481 | |
|
|
1482 | =head3 Examples |
|
|
1483 | |
|
|
1484 | Example: Try to exit cleanly on SIGINT and SIGTERM. |
|
|
1485 | |
|
|
1486 | static void |
|
|
1487 | sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) |
|
|
1488 | { |
|
|
1489 | ev_unloop (loop, EVUNLOOP_ALL); |
|
|
1490 | } |
|
|
1491 | |
|
|
1492 | struct ev_signal signal_watcher; |
|
|
1493 | ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
|
|
1494 | ev_signal_start (loop, &sigint_cb); |
|
|
1495 | |
1381 | |
1496 | |
1382 | =head2 C<ev_child> - watch out for process status changes |
1497 | =head2 C<ev_child> - watch out for process status changes |
1383 | |
1498 | |
1384 | Child watchers trigger when your process receives a SIGCHLD in response to |
1499 | Child watchers trigger when your process receives a SIGCHLD in response to |
1385 | some child status changes (most typically when a child of yours dies). |
1500 | some child status changes (most typically when a child of yours dies). It |
|
|
1501 | is permissible to install a child watcher I<after> the child has been |
|
|
1502 | forked (which implies it might have already exited), as long as the event |
|
|
1503 | loop isn't entered (or is continued from a watcher). |
|
|
1504 | |
|
|
1505 | Only the default event loop is capable of handling signals, and therefore |
|
|
1506 | you can only rgeister child watchers in the default event loop. |
|
|
1507 | |
|
|
1508 | =head3 Process Interaction |
|
|
1509 | |
|
|
1510 | Libev grabs C<SIGCHLD> as soon as the default event loop is |
|
|
1511 | initialised. This is necessary to guarantee proper behaviour even if |
|
|
1512 | the first child watcher is started after the child exits. The occurance |
|
|
1513 | of C<SIGCHLD> is recorded asynchronously, but child reaping is done |
|
|
1514 | synchronously as part of the event loop processing. Libev always reaps all |
|
|
1515 | children, even ones not watched. |
|
|
1516 | |
|
|
1517 | =head3 Overriding the Built-In Processing |
|
|
1518 | |
|
|
1519 | Libev offers no special support for overriding the built-in child |
|
|
1520 | processing, but if your application collides with libev's default child |
|
|
1521 | handler, you can override it easily by installing your own handler for |
|
|
1522 | C<SIGCHLD> after initialising the default loop, and making sure the |
|
|
1523 | default loop never gets destroyed. You are encouraged, however, to use an |
|
|
1524 | event-based approach to child reaping and thus use libev's support for |
|
|
1525 | that, so other libev users can use C<ev_child> watchers freely. |
1386 | |
1526 | |
1387 | =head3 Watcher-Specific Functions and Data Members |
1527 | =head3 Watcher-Specific Functions and Data Members |
1388 | |
1528 | |
1389 | =over 4 |
1529 | =over 4 |
1390 | |
1530 | |
1391 | =item ev_child_init (ev_child *, callback, int pid) |
1531 | =item ev_child_init (ev_child *, callback, int pid, int trace) |
1392 | |
1532 | |
1393 | =item ev_child_set (ev_child *, int pid) |
1533 | =item ev_child_set (ev_child *, int pid, int trace) |
1394 | |
1534 | |
1395 | Configures the watcher to wait for status changes of process C<pid> (or |
1535 | Configures the watcher to wait for status changes of process C<pid> (or |
1396 | I<any> process if C<pid> is specified as C<0>). The callback can look |
1536 | I<any> process if C<pid> is specified as C<0>). The callback can look |
1397 | at the C<rstatus> member of the C<ev_child> watcher structure to see |
1537 | at the C<rstatus> member of the C<ev_child> watcher structure to see |
1398 | the status word (use the macros from C<sys/wait.h> and see your systems |
1538 | the status word (use the macros from C<sys/wait.h> and see your systems |
1399 | C<waitpid> documentation). The C<rpid> member contains the pid of the |
1539 | C<waitpid> documentation). The C<rpid> member contains the pid of the |
1400 | process causing the status change. |
1540 | process causing the status change. C<trace> must be either C<0> (only |
|
|
1541 | activate the watcher when the process terminates) or C<1> (additionally |
|
|
1542 | activate the watcher when the process is stopped or continued). |
1401 | |
1543 | |
1402 | =item int pid [read-only] |
1544 | =item int pid [read-only] |
1403 | |
1545 | |
1404 | The process id this watcher watches out for, or C<0>, meaning any process id. |
1546 | The process id this watcher watches out for, or C<0>, meaning any process id. |
1405 | |
1547 | |
… | |
… | |
1412 | The process exit/trace status caused by C<rpid> (see your systems |
1554 | The process exit/trace status caused by C<rpid> (see your systems |
1413 | C<waitpid> and C<sys/wait.h> documentation for details). |
1555 | C<waitpid> and C<sys/wait.h> documentation for details). |
1414 | |
1556 | |
1415 | =back |
1557 | =back |
1416 | |
1558 | |
1417 | Example: Try to exit cleanly on SIGINT and SIGTERM. |
1559 | =head3 Examples |
|
|
1560 | |
|
|
1561 | Example: C<fork()> a new process and install a child handler to wait for |
|
|
1562 | its completion. |
|
|
1563 | |
|
|
1564 | ev_child cw; |
1418 | |
1565 | |
1419 | static void |
1566 | static void |
1420 | sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) |
1567 | child_cb (EV_P_ struct ev_child *w, int revents) |
1421 | { |
1568 | { |
1422 | ev_unloop (loop, EVUNLOOP_ALL); |
1569 | ev_child_stop (EV_A_ w); |
|
|
1570 | printf ("process %d exited with status %x\n", w->rpid, w->rstatus); |
1423 | } |
1571 | } |
1424 | |
1572 | |
1425 | struct ev_signal signal_watcher; |
1573 | pid_t pid = fork (); |
1426 | ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
1574 | |
1427 | ev_signal_start (loop, &sigint_cb); |
1575 | if (pid < 0) |
|
|
1576 | // error |
|
|
1577 | else if (pid == 0) |
|
|
1578 | { |
|
|
1579 | // the forked child executes here |
|
|
1580 | exit (1); |
|
|
1581 | } |
|
|
1582 | else |
|
|
1583 | { |
|
|
1584 | ev_child_init (&cw, child_cb, pid, 0); |
|
|
1585 | ev_child_start (EV_DEFAULT_ &cw); |
|
|
1586 | } |
1428 | |
1587 | |
1429 | |
1588 | |
1430 | =head2 C<ev_stat> - did the file attributes just change? |
1589 | =head2 C<ev_stat> - did the file attributes just change? |
1431 | |
1590 | |
1432 | This watches a filesystem path for attribute changes. That is, it calls |
1591 | This watches a filesystem path for attribute changes. That is, it calls |
… | |
… | |
1461 | semantics of C<ev_stat> watchers, which means that libev sometimes needs |
1620 | semantics of C<ev_stat> watchers, which means that libev sometimes needs |
1462 | to fall back to regular polling again even with inotify, but changes are |
1621 | to fall back to regular polling again even with inotify, but changes are |
1463 | usually detected immediately, and if the file exists there will be no |
1622 | usually detected immediately, and if the file exists there will be no |
1464 | polling. |
1623 | polling. |
1465 | |
1624 | |
|
|
1625 | =head3 ABI Issues (Largefile Support) |
|
|
1626 | |
|
|
1627 | Libev by default (unless the user overrides this) uses the default |
|
|
1628 | compilation environment, which means that on systems with optionally |
|
|
1629 | disabled large file support, you get the 32 bit version of the stat |
|
|
1630 | structure. When using the library from programs that change the ABI to |
|
|
1631 | use 64 bit file offsets the programs will fail. In that case you have to |
|
|
1632 | compile libev with the same flags to get binary compatibility. This is |
|
|
1633 | obviously the case with any flags that change the ABI, but the problem is |
|
|
1634 | most noticably with ev_stat and largefile support. |
|
|
1635 | |
|
|
1636 | =head3 Inotify |
|
|
1637 | |
|
|
1638 | When C<inotify (7)> support has been compiled into libev (generally only |
|
|
1639 | available on Linux) and present at runtime, it will be used to speed up |
|
|
1640 | change detection where possible. The inotify descriptor will be created lazily |
|
|
1641 | when the first C<ev_stat> watcher is being started. |
|
|
1642 | |
|
|
1643 | Inotify presense does not change the semantics of C<ev_stat> watchers |
|
|
1644 | except that changes might be detected earlier, and in some cases, to avoid |
|
|
1645 | making regular C<stat> calls. Even in the presense of inotify support |
|
|
1646 | there are many cases where libev has to resort to regular C<stat> polling. |
|
|
1647 | |
|
|
1648 | (There is no support for kqueue, as apparently it cannot be used to |
|
|
1649 | implement this functionality, due to the requirement of having a file |
|
|
1650 | descriptor open on the object at all times). |
|
|
1651 | |
|
|
1652 | =head3 The special problem of stat time resolution |
|
|
1653 | |
|
|
1654 | The C<stat ()> syscall only supports full-second resolution portably, and |
|
|
1655 | even on systems where the resolution is higher, many filesystems still |
|
|
1656 | only support whole seconds. |
|
|
1657 | |
|
|
1658 | That means that, if the time is the only thing that changes, you might |
|
|
1659 | miss updates: on the first update, C<ev_stat> detects a change and calls |
|
|
1660 | your callback, which does something. When there is another update within |
|
|
1661 | the same second, C<ev_stat> will be unable to detect it. |
|
|
1662 | |
|
|
1663 | The solution to this is to delay acting on a change for a second (or till |
|
|
1664 | the next second boundary), using a roughly one-second delay C<ev_timer> |
|
|
1665 | (C<ev_timer_set (w, 0., 1.01); ev_timer_again (loop, w)>). The C<.01> |
|
|
1666 | is added to work around small timing inconsistencies of some operating |
|
|
1667 | systems. |
|
|
1668 | |
1466 | =head3 Watcher-Specific Functions and Data Members |
1669 | =head3 Watcher-Specific Functions and Data Members |
1467 | |
1670 | |
1468 | =over 4 |
1671 | =over 4 |
1469 | |
1672 | |
1470 | =item ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval) |
1673 | =item ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval) |
… | |
… | |
1479 | |
1682 | |
1480 | The callback will be receive C<EV_STAT> when a change was detected, |
1683 | The callback will be receive C<EV_STAT> when a change was detected, |
1481 | relative to the attributes at the time the watcher was started (or the |
1684 | relative to the attributes at the time the watcher was started (or the |
1482 | last change was detected). |
1685 | last change was detected). |
1483 | |
1686 | |
1484 | =item ev_stat_stat (ev_stat *) |
1687 | =item ev_stat_stat (loop, ev_stat *) |
1485 | |
1688 | |
1486 | Updates the stat buffer immediately with new values. If you change the |
1689 | Updates the stat buffer immediately with new values. If you change the |
1487 | watched path in your callback, you could call this fucntion to avoid |
1690 | watched path in your callback, you could call this fucntion to avoid |
1488 | detecting this change (while introducing a race condition). Can also be |
1691 | detecting this change (while introducing a race condition). Can also be |
1489 | useful simply to find out the new values. |
1692 | useful simply to find out the new values. |
… | |
… | |
1507 | =item const char *path [read-only] |
1710 | =item const char *path [read-only] |
1508 | |
1711 | |
1509 | The filesystem path that is being watched. |
1712 | The filesystem path that is being watched. |
1510 | |
1713 | |
1511 | =back |
1714 | =back |
|
|
1715 | |
|
|
1716 | =head3 Examples |
1512 | |
1717 | |
1513 | Example: Watch C</etc/passwd> for attribute changes. |
1718 | Example: Watch C</etc/passwd> for attribute changes. |
1514 | |
1719 | |
1515 | static void |
1720 | static void |
1516 | passwd_cb (struct ev_loop *loop, ev_stat *w, int revents) |
1721 | passwd_cb (struct ev_loop *loop, ev_stat *w, int revents) |
… | |
… | |
1529 | } |
1734 | } |
1530 | |
1735 | |
1531 | ... |
1736 | ... |
1532 | ev_stat passwd; |
1737 | ev_stat passwd; |
1533 | |
1738 | |
1534 | ev_stat_init (&passwd, passwd_cb, "/etc/passwd"); |
1739 | ev_stat_init (&passwd, passwd_cb, "/etc/passwd", 0.); |
1535 | ev_stat_start (loop, &passwd); |
1740 | ev_stat_start (loop, &passwd); |
|
|
1741 | |
|
|
1742 | Example: Like above, but additionally use a one-second delay so we do not |
|
|
1743 | miss updates (however, frequent updates will delay processing, too, so |
|
|
1744 | one might do the work both on C<ev_stat> callback invocation I<and> on |
|
|
1745 | C<ev_timer> callback invocation). |
|
|
1746 | |
|
|
1747 | static ev_stat passwd; |
|
|
1748 | static ev_timer timer; |
|
|
1749 | |
|
|
1750 | static void |
|
|
1751 | timer_cb (EV_P_ ev_timer *w, int revents) |
|
|
1752 | { |
|
|
1753 | ev_timer_stop (EV_A_ w); |
|
|
1754 | |
|
|
1755 | /* now it's one second after the most recent passwd change */ |
|
|
1756 | } |
|
|
1757 | |
|
|
1758 | static void |
|
|
1759 | stat_cb (EV_P_ ev_stat *w, int revents) |
|
|
1760 | { |
|
|
1761 | /* reset the one-second timer */ |
|
|
1762 | ev_timer_again (EV_A_ &timer); |
|
|
1763 | } |
|
|
1764 | |
|
|
1765 | ... |
|
|
1766 | ev_stat_init (&passwd, stat_cb, "/etc/passwd", 0.); |
|
|
1767 | ev_stat_start (loop, &passwd); |
|
|
1768 | ev_timer_init (&timer, timer_cb, 0., 1.01); |
1536 | |
1769 | |
1537 | |
1770 | |
1538 | =head2 C<ev_idle> - when you've got nothing better to do... |
1771 | =head2 C<ev_idle> - when you've got nothing better to do... |
1539 | |
1772 | |
1540 | Idle watchers trigger events when no other events of the same or higher |
1773 | Idle watchers trigger events when no other events of the same or higher |
… | |
… | |
1566 | kind. There is a C<ev_idle_set> macro, but using it is utterly pointless, |
1799 | kind. There is a C<ev_idle_set> macro, but using it is utterly pointless, |
1567 | believe me. |
1800 | believe me. |
1568 | |
1801 | |
1569 | =back |
1802 | =back |
1570 | |
1803 | |
|
|
1804 | =head3 Examples |
|
|
1805 | |
1571 | Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the |
1806 | Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the |
1572 | callback, free it. Also, use no error checking, as usual. |
1807 | callback, free it. Also, use no error checking, as usual. |
1573 | |
1808 | |
1574 | static void |
1809 | static void |
1575 | idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents) |
1810 | idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents) |
1576 | { |
1811 | { |
1577 | free (w); |
1812 | free (w); |
1578 | // now do something you wanted to do when the program has |
1813 | // now do something you wanted to do when the program has |
1579 | // no longer asnything immediate to do. |
1814 | // no longer anything immediate to do. |
1580 | } |
1815 | } |
1581 | |
1816 | |
1582 | struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle)); |
1817 | struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle)); |
1583 | ev_idle_init (idle_watcher, idle_cb); |
1818 | ev_idle_init (idle_watcher, idle_cb); |
1584 | ev_idle_start (loop, idle_cb); |
1819 | ev_idle_start (loop, idle_cb); |
… | |
… | |
1646 | parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set> |
1881 | parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set> |
1647 | macros, but using them is utterly, utterly and completely pointless. |
1882 | macros, but using them is utterly, utterly and completely pointless. |
1648 | |
1883 | |
1649 | =back |
1884 | =back |
1650 | |
1885 | |
|
|
1886 | =head3 Examples |
|
|
1887 | |
1651 | There are a number of principal ways to embed other event loops or modules |
1888 | There are a number of principal ways to embed other event loops or modules |
1652 | into libev. Here are some ideas on how to include libadns into libev |
1889 | into libev. Here are some ideas on how to include libadns into libev |
1653 | (there is a Perl module named C<EV::ADNS> that does this, which you could |
1890 | (there is a Perl module named C<EV::ADNS> that does this, which you could |
1654 | use for an actually working example. Another Perl module named C<EV::Glib> |
1891 | use for an actually working example. Another Perl module named C<EV::Glib> |
1655 | embeds a Glib main context into libev, and finally, C<Glib::EV> embeds EV |
1892 | embeds a Glib main context into libev, and finally, C<Glib::EV> embeds EV |
… | |
… | |
1823 | portable one. |
2060 | portable one. |
1824 | |
2061 | |
1825 | So when you want to use this feature you will always have to be prepared |
2062 | So when you want to use this feature you will always have to be prepared |
1826 | that you cannot get an embeddable loop. The recommended way to get around |
2063 | that you cannot get an embeddable loop. The recommended way to get around |
1827 | this is to have a separate variables for your embeddable loop, try to |
2064 | this is to have a separate variables for your embeddable loop, try to |
1828 | create it, and if that fails, use the normal loop for everything: |
2065 | create it, and if that fails, use the normal loop for everything. |
|
|
2066 | |
|
|
2067 | =head3 Watcher-Specific Functions and Data Members |
|
|
2068 | |
|
|
2069 | =over 4 |
|
|
2070 | |
|
|
2071 | =item ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop) |
|
|
2072 | |
|
|
2073 | =item ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop) |
|
|
2074 | |
|
|
2075 | Configures the watcher to embed the given loop, which must be |
|
|
2076 | embeddable. If the callback is C<0>, then C<ev_embed_sweep> will be |
|
|
2077 | invoked automatically, otherwise it is the responsibility of the callback |
|
|
2078 | to invoke it (it will continue to be called until the sweep has been done, |
|
|
2079 | if you do not want thta, you need to temporarily stop the embed watcher). |
|
|
2080 | |
|
|
2081 | =item ev_embed_sweep (loop, ev_embed *) |
|
|
2082 | |
|
|
2083 | Make a single, non-blocking sweep over the embedded loop. This works |
|
|
2084 | similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most |
|
|
2085 | apropriate way for embedded loops. |
|
|
2086 | |
|
|
2087 | =item struct ev_loop *other [read-only] |
|
|
2088 | |
|
|
2089 | The embedded event loop. |
|
|
2090 | |
|
|
2091 | =back |
|
|
2092 | |
|
|
2093 | =head3 Examples |
|
|
2094 | |
|
|
2095 | Example: Try to get an embeddable event loop and embed it into the default |
|
|
2096 | event loop. If that is not possible, use the default loop. The default |
|
|
2097 | loop is stored in C<loop_hi>, while the mebeddable loop is stored in |
|
|
2098 | C<loop_lo> (which is C<loop_hi> in the acse no embeddable loop can be |
|
|
2099 | used). |
1829 | |
2100 | |
1830 | struct ev_loop *loop_hi = ev_default_init (0); |
2101 | struct ev_loop *loop_hi = ev_default_init (0); |
1831 | struct ev_loop *loop_lo = 0; |
2102 | struct ev_loop *loop_lo = 0; |
1832 | struct ev_embed embed; |
2103 | struct ev_embed embed; |
1833 | |
2104 | |
… | |
… | |
1844 | ev_embed_start (loop_hi, &embed); |
2115 | ev_embed_start (loop_hi, &embed); |
1845 | } |
2116 | } |
1846 | else |
2117 | else |
1847 | loop_lo = loop_hi; |
2118 | loop_lo = loop_hi; |
1848 | |
2119 | |
1849 | =head3 Watcher-Specific Functions and Data Members |
2120 | Example: Check if kqueue is available but not recommended and create |
|
|
2121 | a kqueue backend for use with sockets (which usually work with any |
|
|
2122 | kqueue implementation). Store the kqueue/socket-only event loop in |
|
|
2123 | C<loop_socket>. (One might optionally use C<EVFLAG_NOENV>, too). |
1850 | |
2124 | |
1851 | =over 4 |
2125 | struct ev_loop *loop = ev_default_init (0); |
|
|
2126 | struct ev_loop *loop_socket = 0; |
|
|
2127 | struct ev_embed embed; |
|
|
2128 | |
|
|
2129 | if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE) |
|
|
2130 | if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE)) |
|
|
2131 | { |
|
|
2132 | ev_embed_init (&embed, 0, loop_socket); |
|
|
2133 | ev_embed_start (loop, &embed); |
|
|
2134 | } |
1852 | |
2135 | |
1853 | =item ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop) |
2136 | if (!loop_socket) |
|
|
2137 | loop_socket = loop; |
1854 | |
2138 | |
1855 | =item ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop) |
2139 | // now use loop_socket for all sockets, and loop for everything else |
1856 | |
|
|
1857 | Configures the watcher to embed the given loop, which must be |
|
|
1858 | embeddable. If the callback is C<0>, then C<ev_embed_sweep> will be |
|
|
1859 | invoked automatically, otherwise it is the responsibility of the callback |
|
|
1860 | to invoke it (it will continue to be called until the sweep has been done, |
|
|
1861 | if you do not want thta, you need to temporarily stop the embed watcher). |
|
|
1862 | |
|
|
1863 | =item ev_embed_sweep (loop, ev_embed *) |
|
|
1864 | |
|
|
1865 | Make a single, non-blocking sweep over the embedded loop. This works |
|
|
1866 | similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most |
|
|
1867 | apropriate way for embedded loops. |
|
|
1868 | |
|
|
1869 | =item struct ev_loop *other [read-only] |
|
|
1870 | |
|
|
1871 | The embedded event loop. |
|
|
1872 | |
|
|
1873 | =back |
|
|
1874 | |
2140 | |
1875 | |
2141 | |
1876 | =head2 C<ev_fork> - the audacity to resume the event loop after a fork |
2142 | =head2 C<ev_fork> - the audacity to resume the event loop after a fork |
1877 | |
2143 | |
1878 | Fork watchers are called when a C<fork ()> was detected (usually because |
2144 | Fork watchers are called when a C<fork ()> was detected (usually because |
… | |
… | |
1894 | believe me. |
2160 | believe me. |
1895 | |
2161 | |
1896 | =back |
2162 | =back |
1897 | |
2163 | |
1898 | |
2164 | |
|
|
2165 | =head2 C<ev_async> - how to wake up another event loop |
|
|
2166 | |
|
|
2167 | In general, you cannot use an C<ev_loop> from multiple threads or other |
|
|
2168 | asynchronous sources such as signal handlers (as opposed to multiple event |
|
|
2169 | loops - those are of course safe to use in different threads). |
|
|
2170 | |
|
|
2171 | Sometimes, however, you need to wake up another event loop you do not |
|
|
2172 | control, for example because it belongs to another thread. This is what |
|
|
2173 | C<ev_async> watchers do: as long as the C<ev_async> watcher is active, you |
|
|
2174 | can signal it by calling C<ev_async_send>, which is thread- and signal |
|
|
2175 | safe. |
|
|
2176 | |
|
|
2177 | This functionality is very similar to C<ev_signal> watchers, as signals, |
|
|
2178 | too, are asynchronous in nature, and signals, too, will be compressed |
|
|
2179 | (i.e. the number of callback invocations may be less than the number of |
|
|
2180 | C<ev_async_sent> calls). |
|
|
2181 | |
|
|
2182 | Unlike C<ev_signal> watchers, C<ev_async> works with any event loop, not |
|
|
2183 | just the default loop. |
|
|
2184 | |
|
|
2185 | =head3 Queueing |
|
|
2186 | |
|
|
2187 | C<ev_async> does not support queueing of data in any way. The reason |
|
|
2188 | is that the author does not know of a simple (or any) algorithm for a |
|
|
2189 | multiple-writer-single-reader queue that works in all cases and doesn't |
|
|
2190 | need elaborate support such as pthreads. |
|
|
2191 | |
|
|
2192 | That means that if you want to queue data, you have to provide your own |
|
|
2193 | queue. But at least I can tell you would implement locking around your |
|
|
2194 | queue: |
|
|
2195 | |
|
|
2196 | =over 4 |
|
|
2197 | |
|
|
2198 | =item queueing from a signal handler context |
|
|
2199 | |
|
|
2200 | To implement race-free queueing, you simply add to the queue in the signal |
|
|
2201 | handler but you block the signal handler in the watcher callback. Here is an example that does that for |
|
|
2202 | some fictitiuous SIGUSR1 handler: |
|
|
2203 | |
|
|
2204 | static ev_async mysig; |
|
|
2205 | |
|
|
2206 | static void |
|
|
2207 | sigusr1_handler (void) |
|
|
2208 | { |
|
|
2209 | sometype data; |
|
|
2210 | |
|
|
2211 | // no locking etc. |
|
|
2212 | queue_put (data); |
|
|
2213 | ev_async_send (EV_DEFAULT_ &mysig); |
|
|
2214 | } |
|
|
2215 | |
|
|
2216 | static void |
|
|
2217 | mysig_cb (EV_P_ ev_async *w, int revents) |
|
|
2218 | { |
|
|
2219 | sometype data; |
|
|
2220 | sigset_t block, prev; |
|
|
2221 | |
|
|
2222 | sigemptyset (&block); |
|
|
2223 | sigaddset (&block, SIGUSR1); |
|
|
2224 | sigprocmask (SIG_BLOCK, &block, &prev); |
|
|
2225 | |
|
|
2226 | while (queue_get (&data)) |
|
|
2227 | process (data); |
|
|
2228 | |
|
|
2229 | if (sigismember (&prev, SIGUSR1) |
|
|
2230 | sigprocmask (SIG_UNBLOCK, &block, 0); |
|
|
2231 | } |
|
|
2232 | |
|
|
2233 | (Note: pthreads in theory requires you to use C<pthread_setmask> |
|
|
2234 | instead of C<sigprocmask> when you use threads, but libev doesn't do it |
|
|
2235 | either...). |
|
|
2236 | |
|
|
2237 | =item queueing from a thread context |
|
|
2238 | |
|
|
2239 | The strategy for threads is different, as you cannot (easily) block |
|
|
2240 | threads but you can easily preempt them, so to queue safely you need to |
|
|
2241 | employ a traditional mutex lock, such as in this pthread example: |
|
|
2242 | |
|
|
2243 | static ev_async mysig; |
|
|
2244 | static pthread_mutex_t mymutex = PTHREAD_MUTEX_INITIALIZER; |
|
|
2245 | |
|
|
2246 | static void |
|
|
2247 | otherthread (void) |
|
|
2248 | { |
|
|
2249 | // only need to lock the actual queueing operation |
|
|
2250 | pthread_mutex_lock (&mymutex); |
|
|
2251 | queue_put (data); |
|
|
2252 | pthread_mutex_unlock (&mymutex); |
|
|
2253 | |
|
|
2254 | ev_async_send (EV_DEFAULT_ &mysig); |
|
|
2255 | } |
|
|
2256 | |
|
|
2257 | static void |
|
|
2258 | mysig_cb (EV_P_ ev_async *w, int revents) |
|
|
2259 | { |
|
|
2260 | pthread_mutex_lock (&mymutex); |
|
|
2261 | |
|
|
2262 | while (queue_get (&data)) |
|
|
2263 | process (data); |
|
|
2264 | |
|
|
2265 | pthread_mutex_unlock (&mymutex); |
|
|
2266 | } |
|
|
2267 | |
|
|
2268 | =back |
|
|
2269 | |
|
|
2270 | |
|
|
2271 | =head3 Watcher-Specific Functions and Data Members |
|
|
2272 | |
|
|
2273 | =over 4 |
|
|
2274 | |
|
|
2275 | =item ev_async_init (ev_async *, callback) |
|
|
2276 | |
|
|
2277 | Initialises and configures the async watcher - it has no parameters of any |
|
|
2278 | kind. There is a C<ev_asynd_set> macro, but using it is utterly pointless, |
|
|
2279 | believe me. |
|
|
2280 | |
|
|
2281 | =item ev_async_send (loop, ev_async *) |
|
|
2282 | |
|
|
2283 | Sends/signals/activates the given C<ev_async> watcher, that is, feeds |
|
|
2284 | an C<EV_ASYNC> event on the watcher into the event loop. Unlike |
|
|
2285 | C<ev_feed_event>, this call is safe to do in other threads, signal or |
|
|
2286 | similar contexts (see the dicusssion of C<EV_ATOMIC_T> in the embedding |
|
|
2287 | section below on what exactly this means). |
|
|
2288 | |
|
|
2289 | This call incurs the overhead of a syscall only once per loop iteration, |
|
|
2290 | so while the overhead might be noticable, it doesn't apply to repeated |
|
|
2291 | calls to C<ev_async_send>. |
|
|
2292 | |
|
|
2293 | =back |
|
|
2294 | |
|
|
2295 | |
1899 | =head1 OTHER FUNCTIONS |
2296 | =head1 OTHER FUNCTIONS |
1900 | |
2297 | |
1901 | There are some other functions of possible interest. Described. Here. Now. |
2298 | There are some other functions of possible interest. Described. Here. Now. |
1902 | |
2299 | |
1903 | =over 4 |
2300 | =over 4 |
… | |
… | |
2130 | Example: Define a class with an IO and idle watcher, start one of them in |
2527 | Example: Define a class with an IO and idle watcher, start one of them in |
2131 | the constructor. |
2528 | the constructor. |
2132 | |
2529 | |
2133 | class myclass |
2530 | class myclass |
2134 | { |
2531 | { |
2135 | ev_io io; void io_cb (ev::io &w, int revents); |
2532 | ev::io io; void io_cb (ev::io &w, int revents); |
2136 | ev_idle idle void idle_cb (ev::idle &w, int revents); |
2533 | ev:idle idle void idle_cb (ev::idle &w, int revents); |
2137 | |
2534 | |
2138 | myclass (); |
2535 | myclass (int fd) |
2139 | } |
|
|
2140 | |
|
|
2141 | myclass::myclass (int fd) |
|
|
2142 | { |
2536 | { |
2143 | io .set <myclass, &myclass::io_cb > (this); |
2537 | io .set <myclass, &myclass::io_cb > (this); |
2144 | idle.set <myclass, &myclass::idle_cb> (this); |
2538 | idle.set <myclass, &myclass::idle_cb> (this); |
2145 | |
2539 | |
2146 | io.start (fd, ev::READ); |
2540 | io.start (fd, ev::READ); |
|
|
2541 | } |
2147 | } |
2542 | }; |
|
|
2543 | |
|
|
2544 | |
|
|
2545 | =head1 OTHER LANGUAGE BINDINGS |
|
|
2546 | |
|
|
2547 | Libev does not offer other language bindings itself, but bindings for a |
|
|
2548 | numbe rof languages exist in the form of third-party packages. If you know |
|
|
2549 | any interesting language binding in addition to the ones listed here, drop |
|
|
2550 | me a note. |
|
|
2551 | |
|
|
2552 | =over 4 |
|
|
2553 | |
|
|
2554 | =item Perl |
|
|
2555 | |
|
|
2556 | The EV module implements the full libev API and is actually used to test |
|
|
2557 | libev. EV is developed together with libev. Apart from the EV core module, |
|
|
2558 | there are additional modules that implement libev-compatible interfaces |
|
|
2559 | to C<libadns> (C<EV::ADNS>), C<Net::SNMP> (C<Net::SNMP::EV>) and the |
|
|
2560 | C<libglib> event core (C<Glib::EV> and C<EV::Glib>). |
|
|
2561 | |
|
|
2562 | It can be found and installed via CPAN, its homepage is found at |
|
|
2563 | L<http://software.schmorp.de/pkg/EV>. |
|
|
2564 | |
|
|
2565 | =item Ruby |
|
|
2566 | |
|
|
2567 | Tony Arcieri has written a ruby extension that offers access to a subset |
|
|
2568 | of the libev API and adds filehandle abstractions, asynchronous DNS and |
|
|
2569 | more on top of it. It can be found via gem servers. Its homepage is at |
|
|
2570 | L<http://rev.rubyforge.org/>. |
|
|
2571 | |
|
|
2572 | =item D |
|
|
2573 | |
|
|
2574 | Leandro Lucarella has written a D language binding (F<ev.d>) for libev, to |
|
|
2575 | be found at L<http://git.llucax.com.ar/?p=software/ev.d.git;a=summary>. |
|
|
2576 | |
|
|
2577 | =back |
2148 | |
2578 | |
2149 | |
2579 | |
2150 | =head1 MACRO MAGIC |
2580 | =head1 MACRO MAGIC |
2151 | |
2581 | |
2152 | Libev can be compiled with a variety of options, the most fundamantal |
2582 | Libev can be compiled with a variety of options, the most fundamantal |
… | |
… | |
2357 | wants osf handles on win32 (this is the case when the select to |
2787 | wants osf handles on win32 (this is the case when the select to |
2358 | be used is the winsock select). This means that it will call |
2788 | be used is the winsock select). This means that it will call |
2359 | C<_get_osfhandle> on the fd to convert it to an OS handle. Otherwise, |
2789 | C<_get_osfhandle> on the fd to convert it to an OS handle. Otherwise, |
2360 | it is assumed that all these functions actually work on fds, even |
2790 | it is assumed that all these functions actually work on fds, even |
2361 | on win32. Should not be defined on non-win32 platforms. |
2791 | on win32. Should not be defined on non-win32 platforms. |
|
|
2792 | |
|
|
2793 | =item EV_FD_TO_WIN32_HANDLE |
|
|
2794 | |
|
|
2795 | If C<EV_SELECT_IS_WINSOCKET> is enabled, then libev needs a way to map |
|
|
2796 | file descriptors to socket handles. When not defining this symbol (the |
|
|
2797 | default), then libev will call C<_get_osfhandle>, which is usually |
|
|
2798 | correct. In some cases, programs use their own file descriptor management, |
|
|
2799 | in which case they can provide this function to map fds to socket handles. |
2362 | |
2800 | |
2363 | =item EV_USE_POLL |
2801 | =item EV_USE_POLL |
2364 | |
2802 | |
2365 | If defined to be C<1>, libev will compile in support for the C<poll>(2) |
2803 | If defined to be C<1>, libev will compile in support for the C<poll>(2) |
2366 | backend. Otherwise it will be enabled on non-win32 platforms. It |
2804 | backend. Otherwise it will be enabled on non-win32 platforms. It |
… | |
… | |
2400 | |
2838 | |
2401 | If defined to be C<1>, libev will compile in support for the Linux inotify |
2839 | If defined to be C<1>, libev will compile in support for the Linux inotify |
2402 | interface to speed up C<ev_stat> watchers. Its actual availability will |
2840 | interface to speed up C<ev_stat> watchers. Its actual availability will |
2403 | be detected at runtime. |
2841 | be detected at runtime. |
2404 | |
2842 | |
|
|
2843 | =item EV_ATOMIC_T |
|
|
2844 | |
|
|
2845 | Libev requires an integer type (suitable for storing C<0> or C<1>) whose |
|
|
2846 | access is atomic with respect to other threads or signal contexts. No such |
|
|
2847 | type is easily found in the C language, so you can provide your own type |
|
|
2848 | that you know is safe for your purposes. It is used both for signal handler "locking" |
|
|
2849 | as well as for signal and thread safety in C<ev_async> watchers. |
|
|
2850 | |
|
|
2851 | In the absense of this define, libev will use C<sig_atomic_t volatile> |
|
|
2852 | (from F<signal.h>), which is usually good enough on most platforms. |
|
|
2853 | |
2405 | =item EV_H |
2854 | =item EV_H |
2406 | |
2855 | |
2407 | The name of the F<ev.h> header file used to include it. The default if |
2856 | The name of the F<ev.h> header file used to include it. The default if |
2408 | undefined is C<< <ev.h> >> in F<event.h> and C<"ev.h"> in F<ev.c>. This |
2857 | undefined is C<"ev.h"> in F<event.h>, F<ev.c> and F<ev++.h>. This can be |
2409 | can be used to virtually rename the F<ev.h> header file in case of conflicts. |
2858 | used to virtually rename the F<ev.h> header file in case of conflicts. |
2410 | |
2859 | |
2411 | =item EV_CONFIG_H |
2860 | =item EV_CONFIG_H |
2412 | |
2861 | |
2413 | If C<EV_STANDALONE> isn't C<1>, this variable can be used to override |
2862 | If C<EV_STANDALONE> isn't C<1>, this variable can be used to override |
2414 | F<ev.c>'s idea of where to find the F<config.h> file, similarly to |
2863 | F<ev.c>'s idea of where to find the F<config.h> file, similarly to |
2415 | C<EV_H>, above. |
2864 | C<EV_H>, above. |
2416 | |
2865 | |
2417 | =item EV_EVENT_H |
2866 | =item EV_EVENT_H |
2418 | |
2867 | |
2419 | Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea |
2868 | Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea |
2420 | of how the F<event.h> header can be found. |
2869 | of how the F<event.h> header can be found, the default is C<"event.h">. |
2421 | |
2870 | |
2422 | =item EV_PROTOTYPES |
2871 | =item EV_PROTOTYPES |
2423 | |
2872 | |
2424 | If defined to be C<0>, then F<ev.h> will not define any function |
2873 | If defined to be C<0>, then F<ev.h> will not define any function |
2425 | prototypes, but still define all the structs and other symbols. This is |
2874 | prototypes, but still define all the structs and other symbols. This is |
… | |
… | |
2476 | =item EV_FORK_ENABLE |
2925 | =item EV_FORK_ENABLE |
2477 | |
2926 | |
2478 | If undefined or defined to be C<1>, then fork watchers are supported. If |
2927 | If undefined or defined to be C<1>, then fork watchers are supported. If |
2479 | defined to be C<0>, then they are not. |
2928 | defined to be C<0>, then they are not. |
2480 | |
2929 | |
|
|
2930 | =item EV_ASYNC_ENABLE |
|
|
2931 | |
|
|
2932 | If undefined or defined to be C<1>, then async watchers are supported. If |
|
|
2933 | defined to be C<0>, then they are not. |
|
|
2934 | |
2481 | =item EV_MINIMAL |
2935 | =item EV_MINIMAL |
2482 | |
2936 | |
2483 | If you need to shave off some kilobytes of code at the expense of some |
2937 | If you need to shave off some kilobytes of code at the expense of some |
2484 | speed, define this symbol to C<1>. Currently only used for gcc to override |
2938 | speed, define this symbol to C<1>. Currently only used for gcc to override |
2485 | some inlining decisions, saves roughly 30% codesize of amd64. |
2939 | some inlining decisions, saves roughly 30% codesize of amd64. |
… | |
… | |
2491 | than enough. If you need to manage thousands of children you might want to |
2945 | than enough. If you need to manage thousands of children you might want to |
2492 | increase this value (I<must> be a power of two). |
2946 | increase this value (I<must> be a power of two). |
2493 | |
2947 | |
2494 | =item EV_INOTIFY_HASHSIZE |
2948 | =item EV_INOTIFY_HASHSIZE |
2495 | |
2949 | |
2496 | C<ev_staz> watchers use a small hash table to distribute workload by |
2950 | C<ev_stat> watchers use a small hash table to distribute workload by |
2497 | inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>), |
2951 | inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>), |
2498 | usually more than enough. If you need to manage thousands of C<ev_stat> |
2952 | usually more than enough. If you need to manage thousands of C<ev_stat> |
2499 | watchers you might want to increase this value (I<must> be a power of |
2953 | watchers you might want to increase this value (I<must> be a power of |
2500 | two). |
2954 | two). |
2501 | |
2955 | |
… | |
… | |
2597 | |
3051 | |
2598 | =item Starting and stopping timer/periodic watchers: O(log skipped_other_timers) |
3052 | =item Starting and stopping timer/periodic watchers: O(log skipped_other_timers) |
2599 | |
3053 | |
2600 | This means that, when you have a watcher that triggers in one hour and |
3054 | This means that, when you have a watcher that triggers in one hour and |
2601 | there are 100 watchers that would trigger before that then inserting will |
3055 | there are 100 watchers that would trigger before that then inserting will |
2602 | have to skip those 100 watchers. |
3056 | have to skip roughly seven (C<ld 100>) of these watchers. |
2603 | |
3057 | |
2604 | =item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers) |
3058 | =item Changing timer/periodic watchers (by autorepeat or calling again): O(log skipped_other_timers) |
2605 | |
3059 | |
2606 | That means that for changing a timer costs less than removing/adding them |
3060 | That means that changing a timer costs less than removing/adding them |
2607 | as only the relative motion in the event queue has to be paid for. |
3061 | as only the relative motion in the event queue has to be paid for. |
2608 | |
3062 | |
2609 | =item Starting io/check/prepare/idle/signal/child watchers: O(1) |
3063 | =item Starting io/check/prepare/idle/signal/child/fork/async watchers: O(1) |
2610 | |
3064 | |
2611 | These just add the watcher into an array or at the head of a list. |
3065 | These just add the watcher into an array or at the head of a list. |
|
|
3066 | |
2612 | =item Stopping check/prepare/idle watchers: O(1) |
3067 | =item Stopping check/prepare/idle/fork/async watchers: O(1) |
2613 | |
3068 | |
2614 | =item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE)) |
3069 | =item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE)) |
2615 | |
3070 | |
2616 | These watchers are stored in lists then need to be walked to find the |
3071 | These watchers are stored in lists then need to be walked to find the |
2617 | correct watcher to remove. The lists are usually short (you don't usually |
3072 | correct watcher to remove. The lists are usually short (you don't usually |
2618 | have many watchers waiting for the same fd or signal). |
3073 | have many watchers waiting for the same fd or signal). |
2619 | |
3074 | |
2620 | =item Finding the next timer per loop iteration: O(1) |
3075 | =item Finding the next timer in each loop iteration: O(1) |
|
|
3076 | |
|
|
3077 | By virtue of using a binary heap, the next timer is always found at the |
|
|
3078 | beginning of the storage array. |
2621 | |
3079 | |
2622 | =item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd) |
3080 | =item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd) |
2623 | |
3081 | |
2624 | A change means an I/O watcher gets started or stopped, which requires |
3082 | A change means an I/O watcher gets started or stopped, which requires |
2625 | libev to recalculate its status (and possibly tell the kernel). |
3083 | libev to recalculate its status (and possibly tell the kernel, depending |
|
|
3084 | on backend and wether C<ev_io_set> was used). |
2626 | |
3085 | |
2627 | =item Activating one watcher: O(1) |
3086 | =item Activating one watcher (putting it into the pending state): O(1) |
2628 | |
3087 | |
2629 | =item Priority handling: O(number_of_priorities) |
3088 | =item Priority handling: O(number_of_priorities) |
2630 | |
3089 | |
2631 | Priorities are implemented by allocating some space for each |
3090 | Priorities are implemented by allocating some space for each |
2632 | priority. When doing priority-based operations, libev usually has to |
3091 | priority. When doing priority-based operations, libev usually has to |
2633 | linearly search all the priorities. |
3092 | linearly search all the priorities, but starting/stopping and activating |
|
|
3093 | watchers becomes O(1) w.r.t. priority handling. |
|
|
3094 | |
|
|
3095 | =item Sending an ev_async: O(1) |
|
|
3096 | |
|
|
3097 | =item Processing ev_async_send: O(number_of_async_watchers) |
|
|
3098 | |
|
|
3099 | =item Processing signals: O(max_signal_number) |
|
|
3100 | |
|
|
3101 | Sending involves a syscall I<iff> there were no other C<ev_async_send> |
|
|
3102 | calls in the current loop iteration. Checking for async and signal events |
|
|
3103 | involves iterating over all running async watchers or all signal numbers. |
2634 | |
3104 | |
2635 | =back |
3105 | =back |
2636 | |
3106 | |
2637 | |
3107 | |
|
|
3108 | =head1 Win32 platform limitations and workarounds |
|
|
3109 | |
|
|
3110 | Win32 doesn't support any of the standards (e.g. POSIX) that libev |
|
|
3111 | requires, and its I/O model is fundamentally incompatible with the POSIX |
|
|
3112 | model. Libev still offers limited functionality on this platform in |
|
|
3113 | the form of the C<EVBACKEND_SELECT> backend, and only supports socket |
|
|
3114 | descriptors. This only applies when using Win32 natively, not when using |
|
|
3115 | e.g. cygwin. |
|
|
3116 | |
|
|
3117 | There is no supported compilation method available on windows except |
|
|
3118 | embedding it into other applications. |
|
|
3119 | |
|
|
3120 | Due to the many, low, and arbitrary limits on the win32 platform and the |
|
|
3121 | abysmal performance of winsockets, using a large number of sockets is not |
|
|
3122 | recommended (and not reasonable). If your program needs to use more than |
|
|
3123 | a hundred or so sockets, then likely it needs to use a totally different |
|
|
3124 | implementation for windows, as libev offers the POSIX model, which cannot |
|
|
3125 | be implemented efficiently on windows (microsoft monopoly games). |
|
|
3126 | |
|
|
3127 | =over 4 |
|
|
3128 | |
|
|
3129 | =item The winsocket select function |
|
|
3130 | |
|
|
3131 | The winsocket C<select> function doesn't follow POSIX in that it requires |
|
|
3132 | socket I<handles> and not socket I<file descriptors>. This makes select |
|
|
3133 | very inefficient, and also requires a mapping from file descriptors |
|
|
3134 | to socket handles. See the discussion of the C<EV_SELECT_USE_FD_SET>, |
|
|
3135 | C<EV_SELECT_IS_WINSOCKET> and C<EV_FD_TO_WIN32_HANDLE> preprocessor |
|
|
3136 | symbols for more info. |
|
|
3137 | |
|
|
3138 | The configuration for a "naked" win32 using the microsoft runtime |
|
|
3139 | libraries and raw winsocket select is: |
|
|
3140 | |
|
|
3141 | #define EV_USE_SELECT 1 |
|
|
3142 | #define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */ |
|
|
3143 | |
|
|
3144 | Note that winsockets handling of fd sets is O(n), so you can easily get a |
|
|
3145 | complexity in the O(n²) range when using win32. |
|
|
3146 | |
|
|
3147 | =item Limited number of file descriptors |
|
|
3148 | |
|
|
3149 | Windows has numerous arbitrary (and low) limits on things. Early versions |
|
|
3150 | of winsocket's select only supported waiting for a max. of C<64> handles |
|
|
3151 | (probably owning to the fact that all windows kernels can only wait for |
|
|
3152 | C<64> things at the same time internally; microsoft recommends spawning a |
|
|
3153 | chain of threads and wait for 63 handles and the previous thread in each). |
|
|
3154 | |
|
|
3155 | Newer versions support more handles, but you need to define C<FD_SETSIZE> |
|
|
3156 | to some high number (e.g. C<2048>) before compiling the winsocket select |
|
|
3157 | call (which might be in libev or elsewhere, for example, perl does its own |
|
|
3158 | select emulation on windows). |
|
|
3159 | |
|
|
3160 | Another limit is the number of file descriptors in the microsoft runtime |
|
|
3161 | libraries, which by default is C<64> (there must be a hidden I<64> fetish |
|
|
3162 | or something like this inside microsoft). You can increase this by calling |
|
|
3163 | C<_setmaxstdio>, which can increase this limit to C<2048> (another |
|
|
3164 | arbitrary limit), but is broken in many versions of the microsoft runtime |
|
|
3165 | libraries. |
|
|
3166 | |
|
|
3167 | This might get you to about C<512> or C<2048> sockets (depending on |
|
|
3168 | windows version and/or the phase of the moon). To get more, you need to |
|
|
3169 | wrap all I/O functions and provide your own fd management, but the cost of |
|
|
3170 | calling select (O(n²)) will likely make this unworkable. |
|
|
3171 | |
|
|
3172 | =back |
|
|
3173 | |
|
|
3174 | |
2638 | =head1 AUTHOR |
3175 | =head1 AUTHOR |
2639 | |
3176 | |
2640 | Marc Lehmann <libev@schmorp.de>. |
3177 | Marc Lehmann <libev@schmorp.de>. |
2641 | |
3178 | |