… | |
… | |
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 |
|
|
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 | |
|
|
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 |
… | |
… | |
115 | |
130 | |
116 | Returns the current time as libev would use it. Please note that the |
131 | Returns the current time as libev would use it. Please note that the |
117 | C<ev_now> function is usually faster and also often returns the timestamp |
132 | C<ev_now> function is usually faster and also often returns the timestamp |
118 | you actually want to know. |
133 | you actually want to know. |
119 | |
134 | |
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135 | =item ev_sleep (ev_tstamp interval) |
|
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136 | |
|
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137 | Sleep for the given interval: The current thread will be blocked until |
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138 | either it is interrupted or the given time interval has passed. Basically |
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139 | this is a subsecond-resolution C<sleep ()>. |
|
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140 | |
120 | =item int ev_version_major () |
141 | =item int ev_version_major () |
121 | |
142 | |
122 | =item int ev_version_minor () |
143 | =item int ev_version_minor () |
123 | |
144 | |
124 | You can find out the major and minor ABI version numbers of the library |
145 | You can find out the major and minor ABI version numbers of the library |
… | |
… | |
254 | flags. If that is troubling you, check C<ev_backend ()> afterwards). |
275 | flags. If that is troubling you, check C<ev_backend ()> afterwards). |
255 | |
276 | |
256 | 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 |
257 | function. |
278 | function. |
258 | |
279 | |
|
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280 | The default loop is the only loop that can handle C<ev_signal> and |
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281 | C<ev_child> watchers, and to do this, it always registers a handler |
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282 | for C<SIGCHLD>. If this is a problem for your app you can either |
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283 | create a dynamic loop with C<ev_loop_new> that doesn't do that, or you |
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284 | can simply overwrite the C<SIGCHLD> signal handler I<after> calling |
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285 | C<ev_default_init>. |
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286 | |
259 | The flags argument can be used to specify special behaviour or specific |
287 | The flags argument can be used to specify special behaviour or specific |
260 | backends to use, and is usually specified as C<0> (or C<EVFLAG_AUTO>). |
288 | backends to use, and is usually specified as C<0> (or C<EVFLAG_AUTO>). |
261 | |
289 | |
262 | The following flags are supported: |
290 | The following flags are supported: |
263 | |
291 | |
… | |
… | |
284 | enabling this flag. |
312 | enabling this flag. |
285 | |
313 | |
286 | This works by calling C<getpid ()> on every iteration of the loop, |
314 | This works by calling C<getpid ()> on every iteration of the loop, |
287 | and thus this might slow down your event loop if you do a lot of loop |
315 | and thus this might slow down your event loop if you do a lot of loop |
288 | iterations and little real work, but is usually not noticeable (on my |
316 | iterations and little real work, but is usually not noticeable (on my |
289 | Linux system for example, C<getpid> is actually a simple 5-insn sequence |
317 | GNU/Linux system for example, C<getpid> is actually a simple 5-insn sequence |
290 | without a syscall and thus I<very> fast, but my Linux system also has |
318 | without a syscall and thus I<very> fast, but my GNU/Linux system also has |
291 | C<pthread_atfork> which is even faster). |
319 | C<pthread_atfork> which is even faster). |
292 | |
320 | |
293 | The big advantage of this flag is that you can forget about fork (and |
321 | The big advantage of this flag is that you can forget about fork (and |
294 | forget about forgetting to tell libev about forking) when you use this |
322 | forget about forgetting to tell libev about forking) when you use this |
295 | flag. |
323 | flag. |
… | |
… | |
300 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
328 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
301 | |
329 | |
302 | This is your standard select(2) backend. Not I<completely> standard, as |
330 | This is your standard select(2) backend. Not I<completely> standard, as |
303 | libev tries to roll its own fd_set with no limits on the number of fds, |
331 | libev tries to roll its own fd_set with no limits on the number of fds, |
304 | but if that fails, expect a fairly low limit on the number of fds when |
332 | but if that fails, expect a fairly low limit on the number of fds when |
305 | using this backend. It doesn't scale too well (O(highest_fd)), but its usually |
333 | using this backend. It doesn't scale too well (O(highest_fd)), but its |
306 | the fastest backend for a low number of fds. |
334 | usually the fastest backend for a low number of (low-numbered :) fds. |
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335 | |
|
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336 | To get good performance out of this backend you need a high amount of |
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337 | parallelity (most of the file descriptors should be busy). If you are |
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338 | writing a server, you should C<accept ()> in a loop to accept as many |
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339 | connections as possible during one iteration. You might also want to have |
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340 | a look at C<ev_set_io_collect_interval ()> to increase the amount of |
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341 | readyness notifications you get per iteration. |
307 | |
342 | |
308 | =item C<EVBACKEND_POLL> (value 2, poll backend, available everywhere except on windows) |
343 | =item C<EVBACKEND_POLL> (value 2, poll backend, available everywhere except on windows) |
309 | |
344 | |
310 | And this is your standard poll(2) backend. It's more complicated than |
345 | And this is your standard poll(2) backend. It's more complicated |
311 | select, but handles sparse fds better and has no artificial limit on the |
346 | than select, but handles sparse fds better and has no artificial |
312 | number of fds you can use (except it will slow down considerably with a |
347 | limit on the number of fds you can use (except it will slow down |
313 | lot of inactive fds). It scales similarly to select, i.e. O(total_fds). |
348 | considerably with a lot of inactive fds). It scales similarly to select, |
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349 | i.e. O(total_fds). See the entry for C<EVBACKEND_SELECT>, above, for |
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350 | performance tips. |
314 | |
351 | |
315 | =item C<EVBACKEND_EPOLL> (value 4, Linux) |
352 | =item C<EVBACKEND_EPOLL> (value 4, Linux) |
316 | |
353 | |
317 | For few fds, this backend is a bit little slower than poll and select, |
354 | For few fds, this backend is a bit little slower than poll and select, |
318 | but it scales phenomenally better. While poll and select usually scale |
355 | but it scales phenomenally better. While poll and select usually scale |
319 | like O(total_fds) where n is the total number of fds (or the highest fd), |
356 | like O(total_fds) where n is the total number of fds (or the highest fd), |
320 | epoll scales either O(1) or O(active_fds). The epoll design has a number |
357 | epoll scales either O(1) or O(active_fds). The epoll design has a number |
321 | of shortcomings, such as silently dropping events in some hard-to-detect |
358 | of shortcomings, such as silently dropping events in some hard-to-detect |
322 | cases and rewuiring a syscall per fd change, no fork support and bad |
359 | cases and rewiring a syscall per fd change, no fork support and bad |
323 | support for dup: |
360 | support for dup. |
324 | |
361 | |
325 | While stopping, setting and starting an I/O watcher in the same iteration |
362 | While stopping, setting and starting an I/O watcher in the same iteration |
326 | will result in some caching, there is still a syscall per such incident |
363 | will result in some caching, there is still a syscall per such incident |
327 | (because the fd could point to a different file description now), so its |
364 | (because the fd could point to a different file description now), so its |
328 | best to avoid that. Also, C<dup ()>'ed file descriptors might not work |
365 | best to avoid that. Also, C<dup ()>'ed file descriptors might not work |
… | |
… | |
330 | |
367 | |
331 | Please note that epoll sometimes generates spurious notifications, so you |
368 | Please note that epoll sometimes generates spurious notifications, so you |
332 | need to use non-blocking I/O or other means to avoid blocking when no data |
369 | need to use non-blocking I/O or other means to avoid blocking when no data |
333 | (or space) is available. |
370 | (or space) is available. |
334 | |
371 | |
|
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372 | Best performance from this backend is achieved by not unregistering all |
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373 | watchers for a file descriptor until it has been closed, if possible, i.e. |
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374 | keep at least one watcher active per fd at all times. |
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375 | |
|
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376 | While nominally embeddeble in other event loops, this feature is broken in |
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377 | all kernel versions tested so far. |
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378 | |
335 | =item C<EVBACKEND_KQUEUE> (value 8, most BSD clones) |
379 | =item C<EVBACKEND_KQUEUE> (value 8, most BSD clones) |
336 | |
380 | |
337 | Kqueue deserves special mention, as at the time of this writing, it |
381 | Kqueue deserves special mention, as at the time of this writing, it |
338 | was broken on I<all> BSDs (usually it doesn't work with anything but |
382 | was broken on all BSDs except NetBSD (usually it doesn't work reliably |
339 | sockets and pipes, except on Darwin, where of course it's completely |
383 | with anything but sockets and pipes, except on Darwin, where of course |
340 | useless. On NetBSD, it seems to work for all the FD types I tested, so it |
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341 | is used by default there). For this reason it's not being "autodetected" |
384 | it's completely useless). For this reason it's not being "autodetected" |
342 | unless you explicitly specify it explicitly in the flags (i.e. using |
385 | unless you explicitly specify it explicitly in the flags (i.e. using |
343 | C<EVBACKEND_KQUEUE>) or libev was compiled on a known-to-be-good (-enough) |
386 | C<EVBACKEND_KQUEUE>) or libev was compiled on a known-to-be-good (-enough) |
344 | system like NetBSD. |
387 | system like NetBSD. |
345 | |
388 | |
|
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389 | You still can embed kqueue into a normal poll or select backend and use it |
|
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390 | only for sockets (after having made sure that sockets work with kqueue on |
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391 | the target platform). See C<ev_embed> watchers for more info. |
|
|
392 | |
346 | It scales in the same way as the epoll backend, but the interface to the |
393 | It scales in the same way as the epoll backend, but the interface to the |
347 | kernel is more efficient (which says nothing about its actual speed, |
394 | kernel is more efficient (which says nothing about its actual speed, of |
348 | of course). While stopping, setting and starting an I/O watcher does |
395 | course). While stopping, setting and starting an I/O watcher does never |
349 | never cause an extra syscall as with epoll, it still adds up to two event |
396 | cause an extra syscall as with C<EVBACKEND_EPOLL>, it still adds up to |
350 | changes per incident, support for C<fork ()> is very bad and it drops fds |
397 | two event changes per incident, support for C<fork ()> is very bad and it |
351 | silently in similarly hard-to-detetc cases. |
398 | drops fds silently in similarly hard-to-detect cases. |
|
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399 | |
|
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400 | This backend usually performs well under most conditions. |
|
|
401 | |
|
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402 | While nominally embeddable in other event loops, this doesn't work |
|
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403 | everywhere, so you might need to test for this. And since it is broken |
|
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404 | almost everywhere, you should only use it when you have a lot of sockets |
|
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405 | (for which it usually works), by embedding it into another event loop |
|
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406 | (e.g. C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>) and using it only for |
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407 | sockets. |
352 | |
408 | |
353 | =item C<EVBACKEND_DEVPOLL> (value 16, Solaris 8) |
409 | =item C<EVBACKEND_DEVPOLL> (value 16, Solaris 8) |
354 | |
410 | |
355 | This is not implemented yet (and might never be). |
411 | This is not implemented yet (and might never be, unless you send me an |
|
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412 | implementation). According to reports, C</dev/poll> only supports sockets |
|
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413 | and is not embeddable, which would limit the usefulness of this backend |
|
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414 | immensely. |
356 | |
415 | |
357 | =item C<EVBACKEND_PORT> (value 32, Solaris 10) |
416 | =item C<EVBACKEND_PORT> (value 32, Solaris 10) |
358 | |
417 | |
359 | This uses the Solaris 10 event port mechanism. As with everything on Solaris, |
418 | This uses the Solaris 10 event port mechanism. As with everything on Solaris, |
360 | it's really slow, but it still scales very well (O(active_fds)). |
419 | it's really slow, but it still scales very well (O(active_fds)). |
361 | |
420 | |
362 | Please note that solaris event ports can deliver a lot of spurious |
421 | Please note that solaris event ports can deliver a lot of spurious |
363 | notifications, so you need to use non-blocking I/O or other means to avoid |
422 | notifications, so you need to use non-blocking I/O or other means to avoid |
364 | blocking when no data (or space) is available. |
423 | blocking when no data (or space) is available. |
365 | |
424 | |
|
|
425 | While this backend scales well, it requires one system call per active |
|
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426 | file descriptor per loop iteration. For small and medium numbers of file |
|
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427 | descriptors a "slow" C<EVBACKEND_SELECT> or C<EVBACKEND_POLL> backend |
|
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428 | might perform better. |
|
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429 | |
|
|
430 | On the positive side, ignoring the spurious readyness notifications, this |
|
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431 | backend actually performed to specification in all tests and is fully |
|
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432 | embeddable, which is a rare feat among the OS-specific backends. |
|
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433 | |
366 | =item C<EVBACKEND_ALL> |
434 | =item C<EVBACKEND_ALL> |
367 | |
435 | |
368 | Try all backends (even potentially broken ones that wouldn't be tried |
436 | Try all backends (even potentially broken ones that wouldn't be tried |
369 | with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as |
437 | with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as |
370 | C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>. |
438 | C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>. |
371 | |
439 | |
|
|
440 | It is definitely not recommended to use this flag. |
|
|
441 | |
372 | =back |
442 | =back |
373 | |
443 | |
374 | If one or more of these are ored into the flags value, then only these |
444 | If one or more of these are ored into the flags value, then only these |
375 | backends will be tried (in the reverse order as given here). If none are |
445 | backends will be tried (in the reverse order as listed here). If none are |
376 | specified, most compiled-in backend will be tried, usually in reverse |
446 | specified, all backends in C<ev_recommended_backends ()> will be tried. |
377 | order of their flag values :) |
|
|
378 | |
447 | |
379 | The most typical usage is like this: |
448 | The most typical usage is like this: |
380 | |
449 | |
381 | if (!ev_default_loop (0)) |
450 | if (!ev_default_loop (0)) |
382 | fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?"); |
451 | fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?"); |
… | |
… | |
429 | Like C<ev_default_destroy>, but destroys an event loop created by an |
498 | Like C<ev_default_destroy>, but destroys an event loop created by an |
430 | earlier call to C<ev_loop_new>. |
499 | earlier call to C<ev_loop_new>. |
431 | |
500 | |
432 | =item ev_default_fork () |
501 | =item ev_default_fork () |
433 | |
502 | |
|
|
503 | This function sets a flag that causes subsequent C<ev_loop> iterations |
434 | This function reinitialises the kernel state for backends that have |
504 | to reinitialise the kernel state for backends that have one. Despite the |
435 | one. Despite the name, you can call it anytime, but it makes most sense |
505 | name, you can call it anytime, but it makes most sense after forking, in |
436 | after forking, in either the parent or child process (or both, but that |
506 | the child process (or both child and parent, but that again makes little |
437 | again makes little sense). |
507 | sense). You I<must> call it in the child before using any of the libev |
|
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508 | functions, and it will only take effect at the next C<ev_loop> iteration. |
438 | |
509 | |
439 | You I<must> call this function in the child process after forking if and |
510 | On the other hand, you only need to call this function in the child |
440 | only if you want to use the event library in both processes. If you just |
511 | process if and only if you want to use the event library in the child. If |
441 | fork+exec, you don't have to call it. |
512 | you just fork+exec, you don't have to call it at all. |
442 | |
513 | |
443 | The function itself is quite fast and it's usually not a problem to call |
514 | The function itself is quite fast and it's usually not a problem to call |
444 | it just in case after a fork. To make this easy, the function will fit in |
515 | it just in case after a fork. To make this easy, the function will fit in |
445 | quite nicely into a call to C<pthread_atfork>: |
516 | quite nicely into a call to C<pthread_atfork>: |
446 | |
517 | |
447 | pthread_atfork (0, 0, ev_default_fork); |
518 | pthread_atfork (0, 0, ev_default_fork); |
448 | |
519 | |
449 | At the moment, C<EVBACKEND_SELECT> and C<EVBACKEND_POLL> are safe to use |
|
|
450 | without calling this function, so if you force one of those backends you |
|
|
451 | do not need to care. |
|
|
452 | |
|
|
453 | =item ev_loop_fork (loop) |
520 | =item ev_loop_fork (loop) |
454 | |
521 | |
455 | Like C<ev_default_fork>, but acts on an event loop created by |
522 | Like C<ev_default_fork>, but acts on an event loop created by |
456 | C<ev_loop_new>. Yes, you have to call this on every allocated event loop |
523 | C<ev_loop_new>. Yes, you have to call this on every allocated event loop |
457 | after fork, and how you do this is entirely your own problem. |
524 | after fork, and how you do this is entirely your own problem. |
|
|
525 | |
|
|
526 | =item int ev_is_default_loop (loop) |
|
|
527 | |
|
|
528 | Returns true when the given loop actually is the default loop, false otherwise. |
458 | |
529 | |
459 | =item unsigned int ev_loop_count (loop) |
530 | =item unsigned int ev_loop_count (loop) |
460 | |
531 | |
461 | Returns the count of loop iterations for the loop, which is identical to |
532 | Returns the count of loop iterations for the loop, which is identical to |
462 | the number of times libev did poll for new events. It starts at C<0> and |
533 | the number of times libev did poll for new events. It starts at C<0> and |
… | |
… | |
507 | usually a better approach for this kind of thing. |
578 | usually a better approach for this kind of thing. |
508 | |
579 | |
509 | Here are the gory details of what C<ev_loop> does: |
580 | Here are the gory details of what C<ev_loop> does: |
510 | |
581 | |
511 | - Before the first iteration, call any pending watchers. |
582 | - Before the first iteration, call any pending watchers. |
512 | * If there are no active watchers (reference count is zero), return. |
583 | * If EVFLAG_FORKCHECK was used, check for a fork. |
513 | - Queue all prepare watchers and then call all outstanding watchers. |
584 | - If a fork was detected, queue and call all fork watchers. |
|
|
585 | - Queue and call all prepare watchers. |
514 | - If we have been forked, recreate the kernel state. |
586 | - If we have been forked, recreate the kernel state. |
515 | - Update the kernel state with all outstanding changes. |
587 | - Update the kernel state with all outstanding changes. |
516 | - Update the "event loop time". |
588 | - Update the "event loop time". |
517 | - Calculate for how long to block. |
589 | - Calculate for how long to sleep or block, if at all |
|
|
590 | (active idle watchers, EVLOOP_NONBLOCK or not having |
|
|
591 | any active watchers at all will result in not sleeping). |
|
|
592 | - Sleep if the I/O and timer collect interval say so. |
518 | - Block the process, waiting for any events. |
593 | - Block the process, waiting for any events. |
519 | - Queue all outstanding I/O (fd) events. |
594 | - Queue all outstanding I/O (fd) events. |
520 | - Update the "event loop time" and do time jump handling. |
595 | - Update the "event loop time" and do time jump handling. |
521 | - Queue all outstanding timers. |
596 | - Queue all outstanding timers. |
522 | - Queue all outstanding periodics. |
597 | - Queue all outstanding periodics. |
523 | - If no events are pending now, queue all idle watchers. |
598 | - If no events are pending now, queue all idle watchers. |
524 | - Queue all check watchers. |
599 | - Queue all check watchers. |
525 | - Call all queued watchers in reverse order (i.e. check watchers first). |
600 | - Call all queued watchers in reverse order (i.e. check watchers first). |
526 | Signals and child watchers are implemented as I/O watchers, and will |
601 | Signals and child watchers are implemented as I/O watchers, and will |
527 | be handled here by queueing them when their watcher gets executed. |
602 | be handled here by queueing them when their watcher gets executed. |
528 | - If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
603 | - If ev_unloop has been called, or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
529 | were used, return, otherwise continue with step *. |
604 | were used, or there are no active watchers, return, otherwise |
|
|
605 | continue with step *. |
530 | |
606 | |
531 | Example: Queue some jobs and then loop until no events are outsanding |
607 | Example: Queue some jobs and then loop until no events are outstanding |
532 | anymore. |
608 | anymore. |
533 | |
609 | |
534 | ... queue jobs here, make sure they register event watchers as long |
610 | ... queue jobs here, make sure they register event watchers as long |
535 | ... as they still have work to do (even an idle watcher will do..) |
611 | ... as they still have work to do (even an idle watcher will do..) |
536 | ev_loop (my_loop, 0); |
612 | ev_loop (my_loop, 0); |
… | |
… | |
540 | |
616 | |
541 | Can be used to make a call to C<ev_loop> return early (but only after it |
617 | Can be used to make a call to C<ev_loop> return early (but only after it |
542 | has processed all outstanding events). The C<how> argument must be either |
618 | has processed all outstanding events). The C<how> argument must be either |
543 | C<EVUNLOOP_ONE>, which will make the innermost C<ev_loop> call return, or |
619 | C<EVUNLOOP_ONE>, which will make the innermost C<ev_loop> call return, or |
544 | C<EVUNLOOP_ALL>, which will make all nested C<ev_loop> calls return. |
620 | C<EVUNLOOP_ALL>, which will make all nested C<ev_loop> calls return. |
|
|
621 | |
|
|
622 | This "unloop state" will be cleared when entering C<ev_loop> again. |
545 | |
623 | |
546 | =item ev_ref (loop) |
624 | =item ev_ref (loop) |
547 | |
625 | |
548 | =item ev_unref (loop) |
626 | =item ev_unref (loop) |
549 | |
627 | |
… | |
… | |
554 | returning, ev_unref() after starting, and ev_ref() before stopping it. For |
632 | returning, ev_unref() after starting, and ev_ref() before stopping it. For |
555 | example, libev itself uses this for its internal signal pipe: It is not |
633 | example, libev itself uses this for its internal signal pipe: It is not |
556 | visible to the libev user and should not keep C<ev_loop> from exiting if |
634 | visible to the libev user and should not keep C<ev_loop> from exiting if |
557 | no event watchers registered by it are active. It is also an excellent |
635 | no event watchers registered by it are active. It is also an excellent |
558 | way to do this for generic recurring timers or from within third-party |
636 | way to do this for generic recurring timers or from within third-party |
559 | libraries. Just remember to I<unref after start> and I<ref before stop>. |
637 | libraries. Just remember to I<unref after start> and I<ref before stop> |
|
|
638 | (but only if the watcher wasn't active before, or was active before, |
|
|
639 | respectively). |
560 | |
640 | |
561 | Example: Create a signal watcher, but keep it from keeping C<ev_loop> |
641 | Example: Create a signal watcher, but keep it from keeping C<ev_loop> |
562 | running when nothing else is active. |
642 | running when nothing else is active. |
563 | |
643 | |
564 | struct ev_signal exitsig; |
644 | struct ev_signal exitsig; |
… | |
… | |
568 | |
648 | |
569 | Example: For some weird reason, unregister the above signal handler again. |
649 | Example: For some weird reason, unregister the above signal handler again. |
570 | |
650 | |
571 | ev_ref (loop); |
651 | ev_ref (loop); |
572 | ev_signal_stop (loop, &exitsig); |
652 | ev_signal_stop (loop, &exitsig); |
|
|
653 | |
|
|
654 | =item ev_set_io_collect_interval (loop, ev_tstamp interval) |
|
|
655 | |
|
|
656 | =item ev_set_timeout_collect_interval (loop, ev_tstamp interval) |
|
|
657 | |
|
|
658 | These advanced functions influence the time that libev will spend waiting |
|
|
659 | for events. Both are by default C<0>, meaning that libev will try to |
|
|
660 | invoke timer/periodic callbacks and I/O callbacks with minimum latency. |
|
|
661 | |
|
|
662 | Setting these to a higher value (the C<interval> I<must> be >= C<0>) |
|
|
663 | allows libev to delay invocation of I/O and timer/periodic callbacks to |
|
|
664 | increase efficiency of loop iterations. |
|
|
665 | |
|
|
666 | The background is that sometimes your program runs just fast enough to |
|
|
667 | handle one (or very few) event(s) per loop iteration. While this makes |
|
|
668 | the program responsive, it also wastes a lot of CPU time to poll for new |
|
|
669 | events, especially with backends like C<select ()> which have a high |
|
|
670 | overhead for the actual polling but can deliver many events at once. |
|
|
671 | |
|
|
672 | By setting a higher I<io collect interval> you allow libev to spend more |
|
|
673 | time collecting I/O events, so you can handle more events per iteration, |
|
|
674 | at the cost of increasing latency. Timeouts (both C<ev_periodic> and |
|
|
675 | C<ev_timer>) will be not affected. Setting this to a non-null value will |
|
|
676 | introduce an additional C<ev_sleep ()> call into most loop iterations. |
|
|
677 | |
|
|
678 | Likewise, by setting a higher I<timeout collect interval> you allow libev |
|
|
679 | to spend more time collecting timeouts, at the expense of increased |
|
|
680 | latency (the watcher callback will be called later). C<ev_io> watchers |
|
|
681 | will not be affected. Setting this to a non-null value will not introduce |
|
|
682 | any overhead in libev. |
|
|
683 | |
|
|
684 | Many (busy) programs can usually benefit by setting the io collect |
|
|
685 | interval to a value near C<0.1> or so, which is often enough for |
|
|
686 | interactive servers (of course not for games), likewise for timeouts. It |
|
|
687 | usually doesn't make much sense to set it to a lower value than C<0.01>, |
|
|
688 | as this approsaches the timing granularity of most systems. |
573 | |
689 | |
574 | =back |
690 | =back |
575 | |
691 | |
576 | |
692 | |
577 | =head1 ANATOMY OF A WATCHER |
693 | =head1 ANATOMY OF A WATCHER |
… | |
… | |
676 | |
792 | |
677 | =item C<EV_FORK> |
793 | =item C<EV_FORK> |
678 | |
794 | |
679 | The event loop has been resumed in the child process after fork (see |
795 | The event loop has been resumed in the child process after fork (see |
680 | C<ev_fork>). |
796 | C<ev_fork>). |
|
|
797 | |
|
|
798 | =item C<EV_ASYNC> |
|
|
799 | |
|
|
800 | The given async watcher has been asynchronously notified (see C<ev_async>). |
681 | |
801 | |
682 | =item C<EV_ERROR> |
802 | =item C<EV_ERROR> |
683 | |
803 | |
684 | An unspecified error has occured, the watcher has been stopped. This might |
804 | An unspecified error has occured, the watcher has been stopped. This might |
685 | happen because the watcher could not be properly started because libev |
805 | happen because the watcher could not be properly started because libev |
… | |
… | |
903 | In general you can register as many read and/or write event watchers per |
1023 | In general you can register as many read and/or write event watchers per |
904 | fd as you want (as long as you don't confuse yourself). Setting all file |
1024 | fd as you want (as long as you don't confuse yourself). Setting all file |
905 | descriptors to non-blocking mode is also usually a good idea (but not |
1025 | descriptors to non-blocking mode is also usually a good idea (but not |
906 | required if you know what you are doing). |
1026 | required if you know what you are doing). |
907 | |
1027 | |
908 | You have to be careful with dup'ed file descriptors, though. Some backends |
|
|
909 | (the linux epoll backend is a notable example) cannot handle dup'ed file |
|
|
910 | descriptors correctly if you register interest in two or more fds pointing |
|
|
911 | to the same underlying file/socket/etc. description (that is, they share |
|
|
912 | the same underlying "file open"). |
|
|
913 | |
|
|
914 | If you must do this, then force the use of a known-to-be-good backend |
1028 | If you must do this, then force the use of a known-to-be-good backend |
915 | (at the time of this writing, this includes only C<EVBACKEND_SELECT> and |
1029 | (at the time of this writing, this includes only C<EVBACKEND_SELECT> and |
916 | C<EVBACKEND_POLL>). |
1030 | C<EVBACKEND_POLL>). |
917 | |
1031 | |
918 | Another thing you have to watch out for is that it is quite easy to |
1032 | Another thing you have to watch out for is that it is quite easy to |
… | |
… | |
952 | optimisations to libev. |
1066 | optimisations to libev. |
953 | |
1067 | |
954 | =head3 The special problem of dup'ed file descriptors |
1068 | =head3 The special problem of dup'ed file descriptors |
955 | |
1069 | |
956 | Some backends (e.g. epoll), cannot register events for file descriptors, |
1070 | Some backends (e.g. epoll), cannot register events for file descriptors, |
957 | but only events for the underlying file descriptions. That menas when you |
1071 | but only events for the underlying file descriptions. That means when you |
958 | have C<dup ()>'ed file descriptors and register events for them, only one |
1072 | have C<dup ()>'ed file descriptors or weirder constellations, and register |
959 | file descriptor might actually receive events. |
1073 | events for them, only one file descriptor might actually receive events. |
960 | |
1074 | |
961 | There is no workaorund possible except not registering events |
1075 | There is no workaround possible except not registering events |
962 | for potentially C<dup ()>'ed file descriptors or to resort to |
1076 | for potentially C<dup ()>'ed file descriptors, or to resort to |
963 | C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>. |
1077 | C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>. |
964 | |
1078 | |
965 | =head3 The special problem of fork |
1079 | =head3 The special problem of fork |
966 | |
1080 | |
967 | Some backends (epoll, kqueue) do not support C<fork ()> at all or exhibit |
1081 | Some backends (epoll, kqueue) do not support C<fork ()> at all or exhibit |
… | |
… | |
993 | =item int events [read-only] |
1107 | =item int events [read-only] |
994 | |
1108 | |
995 | The events being watched. |
1109 | The events being watched. |
996 | |
1110 | |
997 | =back |
1111 | =back |
|
|
1112 | |
|
|
1113 | =head3 Examples |
998 | |
1114 | |
999 | Example: Call C<stdin_readable_cb> when STDIN_FILENO has become, well |
1115 | Example: Call C<stdin_readable_cb> when STDIN_FILENO has become, well |
1000 | readable, but only once. Since it is likely line-buffered, you could |
1116 | readable, but only once. Since it is likely line-buffered, you could |
1001 | attempt to read a whole line in the callback. |
1117 | attempt to read a whole line in the callback. |
1002 | |
1118 | |
… | |
… | |
1055 | configure a timer to trigger every 10 seconds, then it will trigger at |
1171 | configure a timer to trigger every 10 seconds, then it will trigger at |
1056 | exactly 10 second intervals. If, however, your program cannot keep up with |
1172 | exactly 10 second intervals. If, however, your program cannot keep up with |
1057 | the timer (because it takes longer than those 10 seconds to do stuff) the |
1173 | the timer (because it takes longer than those 10 seconds to do stuff) the |
1058 | timer will not fire more than once per event loop iteration. |
1174 | timer will not fire more than once per event loop iteration. |
1059 | |
1175 | |
1060 | =item ev_timer_again (loop) |
1176 | =item ev_timer_again (loop, ev_timer *) |
1061 | |
1177 | |
1062 | This will act as if the timer timed out and restart it again if it is |
1178 | This will act as if the timer timed out and restart it again if it is |
1063 | repeating. The exact semantics are: |
1179 | repeating. The exact semantics are: |
1064 | |
1180 | |
1065 | If the timer is pending, its pending status is cleared. |
1181 | If the timer is pending, its pending status is cleared. |
… | |
… | |
1100 | or C<ev_timer_again> is called and determines the next timeout (if any), |
1216 | or C<ev_timer_again> is called and determines the next timeout (if any), |
1101 | which is also when any modifications are taken into account. |
1217 | which is also when any modifications are taken into account. |
1102 | |
1218 | |
1103 | =back |
1219 | =back |
1104 | |
1220 | |
|
|
1221 | =head3 Examples |
|
|
1222 | |
1105 | Example: Create a timer that fires after 60 seconds. |
1223 | Example: Create a timer that fires after 60 seconds. |
1106 | |
1224 | |
1107 | static void |
1225 | static void |
1108 | one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
1226 | one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
1109 | { |
1227 | { |
… | |
… | |
1172 | In this configuration the watcher triggers an event at the wallclock time |
1290 | In this configuration the watcher triggers an event at the wallclock time |
1173 | C<at> and doesn't repeat. It will not adjust when a time jump occurs, |
1291 | C<at> and doesn't repeat. It will not adjust when a time jump occurs, |
1174 | that is, if it is to be run at January 1st 2011 then it will run when the |
1292 | that is, if it is to be run at January 1st 2011 then it will run when the |
1175 | system time reaches or surpasses this time. |
1293 | system time reaches or surpasses this time. |
1176 | |
1294 | |
1177 | =item * non-repeating interval timer (at = offset, interval > 0, reschedule_cb = 0) |
1295 | =item * repeating interval timer (at = offset, interval > 0, reschedule_cb = 0) |
1178 | |
1296 | |
1179 | In this mode the watcher will always be scheduled to time out at the next |
1297 | In this mode the watcher will always be scheduled to time out at the next |
1180 | C<at + N * interval> time (for some integer N, which can also be negative) |
1298 | C<at + N * interval> time (for some integer N, which can also be negative) |
1181 | and then repeat, regardless of any time jumps. |
1299 | and then repeat, regardless of any time jumps. |
1182 | |
1300 | |
… | |
… | |
1265 | |
1383 | |
1266 | When active, contains the absolute time that the watcher is supposed to |
1384 | When active, contains the absolute time that the watcher is supposed to |
1267 | trigger next. |
1385 | trigger next. |
1268 | |
1386 | |
1269 | =back |
1387 | =back |
|
|
1388 | |
|
|
1389 | =head3 Examples |
1270 | |
1390 | |
1271 | Example: Call a callback every hour, or, more precisely, whenever the |
1391 | Example: Call a callback every hour, or, more precisely, whenever the |
1272 | system clock is divisible by 3600. The callback invocation times have |
1392 | system clock is divisible by 3600. The callback invocation times have |
1273 | potentially a lot of jittering, but good long-term stability. |
1393 | potentially a lot of jittering, but good long-term stability. |
1274 | |
1394 | |
… | |
… | |
1314 | with the kernel (thus it coexists with your own signal handlers as long |
1434 | with the kernel (thus it coexists with your own signal handlers as long |
1315 | as you don't register any with libev). Similarly, when the last signal |
1435 | as you don't register any with libev). Similarly, when the last signal |
1316 | watcher for a signal is stopped libev will reset the signal handler to |
1436 | watcher for a signal is stopped libev will reset the signal handler to |
1317 | SIG_DFL (regardless of what it was set to before). |
1437 | SIG_DFL (regardless of what it was set to before). |
1318 | |
1438 | |
|
|
1439 | If possible and supported, libev will install its handlers with |
|
|
1440 | C<SA_RESTART> behaviour enabled, so syscalls should not be unduly |
|
|
1441 | interrupted. If you have a problem with syscalls getting interrupted by |
|
|
1442 | signals you can block all signals in an C<ev_check> watcher and unblock |
|
|
1443 | them in an C<ev_prepare> watcher. |
|
|
1444 | |
1319 | =head3 Watcher-Specific Functions and Data Members |
1445 | =head3 Watcher-Specific Functions and Data Members |
1320 | |
1446 | |
1321 | =over 4 |
1447 | =over 4 |
1322 | |
1448 | |
1323 | =item ev_signal_init (ev_signal *, callback, int signum) |
1449 | =item ev_signal_init (ev_signal *, callback, int signum) |
… | |
… | |
1331 | |
1457 | |
1332 | The signal the watcher watches out for. |
1458 | The signal the watcher watches out for. |
1333 | |
1459 | |
1334 | =back |
1460 | =back |
1335 | |
1461 | |
|
|
1462 | =head3 Examples |
|
|
1463 | |
|
|
1464 | Example: Try to exit cleanly on SIGINT and SIGTERM. |
|
|
1465 | |
|
|
1466 | static void |
|
|
1467 | sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) |
|
|
1468 | { |
|
|
1469 | ev_unloop (loop, EVUNLOOP_ALL); |
|
|
1470 | } |
|
|
1471 | |
|
|
1472 | struct ev_signal signal_watcher; |
|
|
1473 | ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
|
|
1474 | ev_signal_start (loop, &sigint_cb); |
|
|
1475 | |
1336 | |
1476 | |
1337 | =head2 C<ev_child> - watch out for process status changes |
1477 | =head2 C<ev_child> - watch out for process status changes |
1338 | |
1478 | |
1339 | Child watchers trigger when your process receives a SIGCHLD in response to |
1479 | Child watchers trigger when your process receives a SIGCHLD in response to |
1340 | some child status changes (most typically when a child of yours dies). |
1480 | some child status changes (most typically when a child of yours dies). It |
|
|
1481 | is permissible to install a child watcher I<after> the child has been |
|
|
1482 | forked (which implies it might have already exited), as long as the event |
|
|
1483 | loop isn't entered (or is continued from a watcher). |
|
|
1484 | |
|
|
1485 | Only the default event loop is capable of handling signals, and therefore |
|
|
1486 | you can only rgeister child watchers in the default event loop. |
|
|
1487 | |
|
|
1488 | =head3 Process Interaction |
|
|
1489 | |
|
|
1490 | Libev grabs C<SIGCHLD> as soon as the default event loop is |
|
|
1491 | initialised. This is necessary to guarantee proper behaviour even if |
|
|
1492 | the first child watcher is started after the child exits. The occurance |
|
|
1493 | of C<SIGCHLD> is recorded asynchronously, but child reaping is done |
|
|
1494 | synchronously as part of the event loop processing. Libev always reaps all |
|
|
1495 | children, even ones not watched. |
|
|
1496 | |
|
|
1497 | =head3 Overriding the Built-In Processing |
|
|
1498 | |
|
|
1499 | Libev offers no special support for overriding the built-in child |
|
|
1500 | processing, but if your application collides with libev's default child |
|
|
1501 | handler, you can override it easily by installing your own handler for |
|
|
1502 | C<SIGCHLD> after initialising the default loop, and making sure the |
|
|
1503 | default loop never gets destroyed. You are encouraged, however, to use an |
|
|
1504 | event-based approach to child reaping and thus use libev's support for |
|
|
1505 | that, so other libev users can use C<ev_child> watchers freely. |
1341 | |
1506 | |
1342 | =head3 Watcher-Specific Functions and Data Members |
1507 | =head3 Watcher-Specific Functions and Data Members |
1343 | |
1508 | |
1344 | =over 4 |
1509 | =over 4 |
1345 | |
1510 | |
1346 | =item ev_child_init (ev_child *, callback, int pid) |
1511 | =item ev_child_init (ev_child *, callback, int pid, int trace) |
1347 | |
1512 | |
1348 | =item ev_child_set (ev_child *, int pid) |
1513 | =item ev_child_set (ev_child *, int pid, int trace) |
1349 | |
1514 | |
1350 | Configures the watcher to wait for status changes of process C<pid> (or |
1515 | Configures the watcher to wait for status changes of process C<pid> (or |
1351 | I<any> process if C<pid> is specified as C<0>). The callback can look |
1516 | I<any> process if C<pid> is specified as C<0>). The callback can look |
1352 | at the C<rstatus> member of the C<ev_child> watcher structure to see |
1517 | at the C<rstatus> member of the C<ev_child> watcher structure to see |
1353 | the status word (use the macros from C<sys/wait.h> and see your systems |
1518 | the status word (use the macros from C<sys/wait.h> and see your systems |
1354 | C<waitpid> documentation). The C<rpid> member contains the pid of the |
1519 | C<waitpid> documentation). The C<rpid> member contains the pid of the |
1355 | process causing the status change. |
1520 | process causing the status change. C<trace> must be either C<0> (only |
|
|
1521 | activate the watcher when the process terminates) or C<1> (additionally |
|
|
1522 | activate the watcher when the process is stopped or continued). |
1356 | |
1523 | |
1357 | =item int pid [read-only] |
1524 | =item int pid [read-only] |
1358 | |
1525 | |
1359 | The process id this watcher watches out for, or C<0>, meaning any process id. |
1526 | The process id this watcher watches out for, or C<0>, meaning any process id. |
1360 | |
1527 | |
… | |
… | |
1367 | The process exit/trace status caused by C<rpid> (see your systems |
1534 | The process exit/trace status caused by C<rpid> (see your systems |
1368 | C<waitpid> and C<sys/wait.h> documentation for details). |
1535 | C<waitpid> and C<sys/wait.h> documentation for details). |
1369 | |
1536 | |
1370 | =back |
1537 | =back |
1371 | |
1538 | |
1372 | Example: Try to exit cleanly on SIGINT and SIGTERM. |
1539 | =head3 Examples |
|
|
1540 | |
|
|
1541 | Example: C<fork()> a new process and install a child handler to wait for |
|
|
1542 | its completion. |
|
|
1543 | |
|
|
1544 | ev_child cw; |
1373 | |
1545 | |
1374 | static void |
1546 | static void |
1375 | sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) |
1547 | child_cb (EV_P_ struct ev_child *w, int revents) |
1376 | { |
1548 | { |
1377 | ev_unloop (loop, EVUNLOOP_ALL); |
1549 | ev_child_stop (EV_A_ w); |
|
|
1550 | printf ("process %d exited with status %x\n", w->rpid, w->rstatus); |
1378 | } |
1551 | } |
1379 | |
1552 | |
1380 | struct ev_signal signal_watcher; |
1553 | pid_t pid = fork (); |
1381 | ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
1554 | |
1382 | ev_signal_start (loop, &sigint_cb); |
1555 | if (pid < 0) |
|
|
1556 | // error |
|
|
1557 | else if (pid == 0) |
|
|
1558 | { |
|
|
1559 | // the forked child executes here |
|
|
1560 | exit (1); |
|
|
1561 | } |
|
|
1562 | else |
|
|
1563 | { |
|
|
1564 | ev_child_init (&cw, child_cb, pid, 0); |
|
|
1565 | ev_child_start (EV_DEFAULT_ &cw); |
|
|
1566 | } |
1383 | |
1567 | |
1384 | |
1568 | |
1385 | =head2 C<ev_stat> - did the file attributes just change? |
1569 | =head2 C<ev_stat> - did the file attributes just change? |
1386 | |
1570 | |
1387 | This watches a filesystem path for attribute changes. That is, it calls |
1571 | This watches a filesystem path for attribute changes. That is, it calls |
… | |
… | |
1416 | semantics of C<ev_stat> watchers, which means that libev sometimes needs |
1600 | semantics of C<ev_stat> watchers, which means that libev sometimes needs |
1417 | to fall back to regular polling again even with inotify, but changes are |
1601 | to fall back to regular polling again even with inotify, but changes are |
1418 | usually detected immediately, and if the file exists there will be no |
1602 | usually detected immediately, and if the file exists there will be no |
1419 | polling. |
1603 | polling. |
1420 | |
1604 | |
|
|
1605 | =head3 Inotify |
|
|
1606 | |
|
|
1607 | When C<inotify (7)> support has been compiled into libev (generally only |
|
|
1608 | available on Linux) and present at runtime, it will be used to speed up |
|
|
1609 | change detection where possible. The inotify descriptor will be created lazily |
|
|
1610 | when the first C<ev_stat> watcher is being started. |
|
|
1611 | |
|
|
1612 | Inotify presense does not change the semantics of C<ev_stat> watchers |
|
|
1613 | except that changes might be detected earlier, and in some cases, to avoid |
|
|
1614 | making regular C<stat> calls. Even in the presense of inotify support |
|
|
1615 | there are many cases where libev has to resort to regular C<stat> polling. |
|
|
1616 | |
|
|
1617 | (There is no support for kqueue, as apparently it cannot be used to |
|
|
1618 | implement this functionality, due to the requirement of having a file |
|
|
1619 | descriptor open on the object at all times). |
|
|
1620 | |
|
|
1621 | =head3 The special problem of stat time resolution |
|
|
1622 | |
|
|
1623 | The C<stat ()> syscall only supports full-second resolution portably, and |
|
|
1624 | even on systems where the resolution is higher, many filesystems still |
|
|
1625 | only support whole seconds. |
|
|
1626 | |
|
|
1627 | That means that, if the time is the only thing that changes, you might |
|
|
1628 | miss updates: on the first update, C<ev_stat> detects a change and calls |
|
|
1629 | your callback, which does something. When there is another update within |
|
|
1630 | the same second, C<ev_stat> will be unable to detect it. |
|
|
1631 | |
|
|
1632 | The solution to this is to delay acting on a change for a second (or till |
|
|
1633 | the next second boundary), using a roughly one-second delay C<ev_timer> |
|
|
1634 | (C<ev_timer_set (w, 0., 1.01); ev_timer_again (loop, w)>). The C<.01> |
|
|
1635 | is added to work around small timing inconsistencies of some operating |
|
|
1636 | systems. |
|
|
1637 | |
1421 | =head3 Watcher-Specific Functions and Data Members |
1638 | =head3 Watcher-Specific Functions and Data Members |
1422 | |
1639 | |
1423 | =over 4 |
1640 | =over 4 |
1424 | |
1641 | |
1425 | =item ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval) |
1642 | =item ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval) |
… | |
… | |
1434 | |
1651 | |
1435 | The callback will be receive C<EV_STAT> when a change was detected, |
1652 | The callback will be receive C<EV_STAT> when a change was detected, |
1436 | relative to the attributes at the time the watcher was started (or the |
1653 | relative to the attributes at the time the watcher was started (or the |
1437 | last change was detected). |
1654 | last change was detected). |
1438 | |
1655 | |
1439 | =item ev_stat_stat (ev_stat *) |
1656 | =item ev_stat_stat (loop, ev_stat *) |
1440 | |
1657 | |
1441 | Updates the stat buffer immediately with new values. If you change the |
1658 | Updates the stat buffer immediately with new values. If you change the |
1442 | watched path in your callback, you could call this fucntion to avoid |
1659 | watched path in your callback, you could call this fucntion to avoid |
1443 | detecting this change (while introducing a race condition). Can also be |
1660 | detecting this change (while introducing a race condition). Can also be |
1444 | useful simply to find out the new values. |
1661 | useful simply to find out the new values. |
… | |
… | |
1462 | =item const char *path [read-only] |
1679 | =item const char *path [read-only] |
1463 | |
1680 | |
1464 | The filesystem path that is being watched. |
1681 | The filesystem path that is being watched. |
1465 | |
1682 | |
1466 | =back |
1683 | =back |
|
|
1684 | |
|
|
1685 | =head3 Examples |
1467 | |
1686 | |
1468 | Example: Watch C</etc/passwd> for attribute changes. |
1687 | Example: Watch C</etc/passwd> for attribute changes. |
1469 | |
1688 | |
1470 | static void |
1689 | static void |
1471 | passwd_cb (struct ev_loop *loop, ev_stat *w, int revents) |
1690 | passwd_cb (struct ev_loop *loop, ev_stat *w, int revents) |
… | |
… | |
1484 | } |
1703 | } |
1485 | |
1704 | |
1486 | ... |
1705 | ... |
1487 | ev_stat passwd; |
1706 | ev_stat passwd; |
1488 | |
1707 | |
1489 | ev_stat_init (&passwd, passwd_cb, "/etc/passwd"); |
1708 | ev_stat_init (&passwd, passwd_cb, "/etc/passwd", 0.); |
1490 | ev_stat_start (loop, &passwd); |
1709 | ev_stat_start (loop, &passwd); |
|
|
1710 | |
|
|
1711 | Example: Like above, but additionally use a one-second delay so we do not |
|
|
1712 | miss updates (however, frequent updates will delay processing, too, so |
|
|
1713 | one might do the work both on C<ev_stat> callback invocation I<and> on |
|
|
1714 | C<ev_timer> callback invocation). |
|
|
1715 | |
|
|
1716 | static ev_stat passwd; |
|
|
1717 | static ev_timer timer; |
|
|
1718 | |
|
|
1719 | static void |
|
|
1720 | timer_cb (EV_P_ ev_timer *w, int revents) |
|
|
1721 | { |
|
|
1722 | ev_timer_stop (EV_A_ w); |
|
|
1723 | |
|
|
1724 | /* now it's one second after the most recent passwd change */ |
|
|
1725 | } |
|
|
1726 | |
|
|
1727 | static void |
|
|
1728 | stat_cb (EV_P_ ev_stat *w, int revents) |
|
|
1729 | { |
|
|
1730 | /* reset the one-second timer */ |
|
|
1731 | ev_timer_again (EV_A_ &timer); |
|
|
1732 | } |
|
|
1733 | |
|
|
1734 | ... |
|
|
1735 | ev_stat_init (&passwd, stat_cb, "/etc/passwd", 0.); |
|
|
1736 | ev_stat_start (loop, &passwd); |
|
|
1737 | ev_timer_init (&timer, timer_cb, 0., 1.01); |
1491 | |
1738 | |
1492 | |
1739 | |
1493 | =head2 C<ev_idle> - when you've got nothing better to do... |
1740 | =head2 C<ev_idle> - when you've got nothing better to do... |
1494 | |
1741 | |
1495 | Idle watchers trigger events when no other events of the same or higher |
1742 | Idle watchers trigger events when no other events of the same or higher |
… | |
… | |
1521 | kind. There is a C<ev_idle_set> macro, but using it is utterly pointless, |
1768 | kind. There is a C<ev_idle_set> macro, but using it is utterly pointless, |
1522 | believe me. |
1769 | believe me. |
1523 | |
1770 | |
1524 | =back |
1771 | =back |
1525 | |
1772 | |
|
|
1773 | =head3 Examples |
|
|
1774 | |
1526 | Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the |
1775 | Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the |
1527 | callback, free it. Also, use no error checking, as usual. |
1776 | callback, free it. Also, use no error checking, as usual. |
1528 | |
1777 | |
1529 | static void |
1778 | static void |
1530 | idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents) |
1779 | idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents) |
1531 | { |
1780 | { |
1532 | free (w); |
1781 | free (w); |
1533 | // now do something you wanted to do when the program has |
1782 | // now do something you wanted to do when the program has |
1534 | // no longer asnything immediate to do. |
1783 | // no longer anything immediate to do. |
1535 | } |
1784 | } |
1536 | |
1785 | |
1537 | struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle)); |
1786 | struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle)); |
1538 | ev_idle_init (idle_watcher, idle_cb); |
1787 | ev_idle_init (idle_watcher, idle_cb); |
1539 | ev_idle_start (loop, idle_cb); |
1788 | ev_idle_start (loop, idle_cb); |
… | |
… | |
1581 | |
1830 | |
1582 | It is recommended to give C<ev_check> watchers highest (C<EV_MAXPRI>) |
1831 | It is recommended to give C<ev_check> watchers highest (C<EV_MAXPRI>) |
1583 | priority, to ensure that they are being run before any other watchers |
1832 | priority, to ensure that they are being run before any other watchers |
1584 | after the poll. Also, C<ev_check> watchers (and C<ev_prepare> watchers, |
1833 | after the poll. Also, C<ev_check> watchers (and C<ev_prepare> watchers, |
1585 | too) should not activate ("feed") events into libev. While libev fully |
1834 | too) should not activate ("feed") events into libev. While libev fully |
1586 | supports this, they will be called before other C<ev_check> watchers did |
1835 | supports this, they will be called before other C<ev_check> watchers |
1587 | their job. As C<ev_check> watchers are often used to embed other event |
1836 | did their job. As C<ev_check> watchers are often used to embed other |
1588 | loops those other event loops might be in an unusable state until their |
1837 | (non-libev) event loops those other event loops might be in an unusable |
1589 | C<ev_check> watcher ran (always remind yourself to coexist peacefully with |
1838 | state until their C<ev_check> watcher ran (always remind yourself to |
1590 | others). |
1839 | coexist peacefully with others). |
1591 | |
1840 | |
1592 | =head3 Watcher-Specific Functions and Data Members |
1841 | =head3 Watcher-Specific Functions and Data Members |
1593 | |
1842 | |
1594 | =over 4 |
1843 | =over 4 |
1595 | |
1844 | |
… | |
… | |
1600 | Initialises and configures the prepare or check watcher - they have no |
1849 | Initialises and configures the prepare or check watcher - they have no |
1601 | parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set> |
1850 | parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set> |
1602 | macros, but using them is utterly, utterly and completely pointless. |
1851 | macros, but using them is utterly, utterly and completely pointless. |
1603 | |
1852 | |
1604 | =back |
1853 | =back |
|
|
1854 | |
|
|
1855 | =head3 Examples |
1605 | |
1856 | |
1606 | There are a number of principal ways to embed other event loops or modules |
1857 | There are a number of principal ways to embed other event loops or modules |
1607 | into libev. Here are some ideas on how to include libadns into libev |
1858 | into libev. Here are some ideas on how to include libadns into libev |
1608 | (there is a Perl module named C<EV::ADNS> that does this, which you could |
1859 | (there is a Perl module named C<EV::ADNS> that does this, which you could |
1609 | use for an actually working example. Another Perl module named C<EV::Glib> |
1860 | use for an actually working example. Another Perl module named C<EV::Glib> |
… | |
… | |
1734 | =head2 C<ev_embed> - when one backend isn't enough... |
1985 | =head2 C<ev_embed> - when one backend isn't enough... |
1735 | |
1986 | |
1736 | This is a rather advanced watcher type that lets you embed one event loop |
1987 | This is a rather advanced watcher type that lets you embed one event loop |
1737 | into another (currently only C<ev_io> events are supported in the embedded |
1988 | into another (currently only C<ev_io> events are supported in the embedded |
1738 | loop, other types of watchers might be handled in a delayed or incorrect |
1989 | loop, other types of watchers might be handled in a delayed or incorrect |
1739 | fashion and must not be used). (See portability notes, below). |
1990 | fashion and must not be used). |
1740 | |
1991 | |
1741 | There are primarily two reasons you would want that: work around bugs and |
1992 | There are primarily two reasons you would want that: work around bugs and |
1742 | prioritise I/O. |
1993 | prioritise I/O. |
1743 | |
1994 | |
1744 | As an example for a bug workaround, the kqueue backend might only support |
1995 | As an example for a bug workaround, the kqueue backend might only support |
… | |
… | |
1778 | portable one. |
2029 | portable one. |
1779 | |
2030 | |
1780 | So when you want to use this feature you will always have to be prepared |
2031 | So when you want to use this feature you will always have to be prepared |
1781 | that you cannot get an embeddable loop. The recommended way to get around |
2032 | that you cannot get an embeddable loop. The recommended way to get around |
1782 | this is to have a separate variables for your embeddable loop, try to |
2033 | this is to have a separate variables for your embeddable loop, try to |
1783 | create it, and if that fails, use the normal loop for everything: |
2034 | create it, and if that fails, use the normal loop for everything. |
|
|
2035 | |
|
|
2036 | =head3 Watcher-Specific Functions and Data Members |
|
|
2037 | |
|
|
2038 | =over 4 |
|
|
2039 | |
|
|
2040 | =item ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop) |
|
|
2041 | |
|
|
2042 | =item ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop) |
|
|
2043 | |
|
|
2044 | Configures the watcher to embed the given loop, which must be |
|
|
2045 | embeddable. If the callback is C<0>, then C<ev_embed_sweep> will be |
|
|
2046 | invoked automatically, otherwise it is the responsibility of the callback |
|
|
2047 | to invoke it (it will continue to be called until the sweep has been done, |
|
|
2048 | if you do not want thta, you need to temporarily stop the embed watcher). |
|
|
2049 | |
|
|
2050 | =item ev_embed_sweep (loop, ev_embed *) |
|
|
2051 | |
|
|
2052 | Make a single, non-blocking sweep over the embedded loop. This works |
|
|
2053 | similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most |
|
|
2054 | apropriate way for embedded loops. |
|
|
2055 | |
|
|
2056 | =item struct ev_loop *other [read-only] |
|
|
2057 | |
|
|
2058 | The embedded event loop. |
|
|
2059 | |
|
|
2060 | =back |
|
|
2061 | |
|
|
2062 | =head3 Examples |
|
|
2063 | |
|
|
2064 | Example: Try to get an embeddable event loop and embed it into the default |
|
|
2065 | event loop. If that is not possible, use the default loop. The default |
|
|
2066 | loop is stored in C<loop_hi>, while the mebeddable loop is stored in |
|
|
2067 | C<loop_lo> (which is C<loop_hi> in the acse no embeddable loop can be |
|
|
2068 | used). |
1784 | |
2069 | |
1785 | struct ev_loop *loop_hi = ev_default_init (0); |
2070 | struct ev_loop *loop_hi = ev_default_init (0); |
1786 | struct ev_loop *loop_lo = 0; |
2071 | struct ev_loop *loop_lo = 0; |
1787 | struct ev_embed embed; |
2072 | struct ev_embed embed; |
1788 | |
2073 | |
… | |
… | |
1799 | ev_embed_start (loop_hi, &embed); |
2084 | ev_embed_start (loop_hi, &embed); |
1800 | } |
2085 | } |
1801 | else |
2086 | else |
1802 | loop_lo = loop_hi; |
2087 | loop_lo = loop_hi; |
1803 | |
2088 | |
1804 | =head2 Portability notes |
2089 | Example: Check if kqueue is available but not recommended and create |
|
|
2090 | a kqueue backend for use with sockets (which usually work with any |
|
|
2091 | kqueue implementation). Store the kqueue/socket-only event loop in |
|
|
2092 | C<loop_socket>. (One might optionally use C<EVFLAG_NOENV>, too). |
1805 | |
2093 | |
1806 | Kqueue is nominally embeddable, but this is broken on all BSDs that I |
2094 | struct ev_loop *loop = ev_default_init (0); |
1807 | tried, in various ways. Usually the embedded event loop will simply never |
2095 | struct ev_loop *loop_socket = 0; |
1808 | receive events, sometimes it will only trigger a few times, sometimes in a |
2096 | struct ev_embed embed; |
1809 | loop. Epoll is also nominally embeddable, but many Linux kernel versions |
2097 | |
1810 | will always eport the epoll fd as ready, even when no events are pending. |
2098 | if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE) |
|
|
2099 | if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE)) |
|
|
2100 | { |
|
|
2101 | ev_embed_init (&embed, 0, loop_socket); |
|
|
2102 | ev_embed_start (loop, &embed); |
|
|
2103 | } |
1811 | |
2104 | |
1812 | While libev allows embedding these backends (they are contained in |
2105 | if (!loop_socket) |
1813 | C<ev_embeddable_backends ()>), take extreme care that it will actually |
2106 | loop_socket = loop; |
1814 | work. |
|
|
1815 | |
2107 | |
1816 | When in doubt, create a dynamic event loop forced to use sockets (this |
2108 | // now use loop_socket for all sockets, and loop for everything else |
1817 | usually works) and possibly another thread and a pipe or so to report to |
|
|
1818 | your main event loop. |
|
|
1819 | |
|
|
1820 | =head3 Watcher-Specific Functions and Data Members |
|
|
1821 | |
|
|
1822 | =over 4 |
|
|
1823 | |
|
|
1824 | =item ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop) |
|
|
1825 | |
|
|
1826 | =item ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop) |
|
|
1827 | |
|
|
1828 | Configures the watcher to embed the given loop, which must be |
|
|
1829 | embeddable. If the callback is C<0>, then C<ev_embed_sweep> will be |
|
|
1830 | invoked automatically, otherwise it is the responsibility of the callback |
|
|
1831 | to invoke it (it will continue to be called until the sweep has been done, |
|
|
1832 | if you do not want thta, you need to temporarily stop the embed watcher). |
|
|
1833 | |
|
|
1834 | =item ev_embed_sweep (loop, ev_embed *) |
|
|
1835 | |
|
|
1836 | Make a single, non-blocking sweep over the embedded loop. This works |
|
|
1837 | similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most |
|
|
1838 | apropriate way for embedded loops. |
|
|
1839 | |
|
|
1840 | =item struct ev_loop *other [read-only] |
|
|
1841 | |
|
|
1842 | The embedded event loop. |
|
|
1843 | |
|
|
1844 | =back |
|
|
1845 | |
2109 | |
1846 | |
2110 | |
1847 | =head2 C<ev_fork> - the audacity to resume the event loop after a fork |
2111 | =head2 C<ev_fork> - the audacity to resume the event loop after a fork |
1848 | |
2112 | |
1849 | Fork watchers are called when a C<fork ()> was detected (usually because |
2113 | Fork watchers are called when a C<fork ()> was detected (usually because |
… | |
… | |
1865 | believe me. |
2129 | believe me. |
1866 | |
2130 | |
1867 | =back |
2131 | =back |
1868 | |
2132 | |
1869 | |
2133 | |
|
|
2134 | =head2 C<ev_async> - how to wake up another event loop |
|
|
2135 | |
|
|
2136 | In general, you cannot use an C<ev_loop> from multiple threads or other |
|
|
2137 | asynchronous sources such as signal handlers (as opposed to multiple event |
|
|
2138 | loops - those are of course safe to use in different threads). |
|
|
2139 | |
|
|
2140 | Sometimes, however, you need to wake up another event loop you do not |
|
|
2141 | control, for example because it belongs to another thread. This is what |
|
|
2142 | C<ev_async> watchers do: as long as the C<ev_async> watcher is active, you |
|
|
2143 | can signal it by calling C<ev_async_send>, which is thread- and signal |
|
|
2144 | safe. |
|
|
2145 | |
|
|
2146 | This functionality is very similar to C<ev_signal> watchers, as signals, |
|
|
2147 | too, are asynchronous in nature, and signals, too, will be compressed |
|
|
2148 | (i.e. the number of callback invocations may be less than the number of |
|
|
2149 | C<ev_async_sent> calls). |
|
|
2150 | |
|
|
2151 | Unlike C<ev_signal> watchers, C<ev_async> works with any event loop, not |
|
|
2152 | just the default loop. |
|
|
2153 | |
|
|
2154 | =head3 Queueing |
|
|
2155 | |
|
|
2156 | C<ev_async> does not support queueing of data in any way. The reason |
|
|
2157 | is that the author does not know of a simple (or any) algorithm for a |
|
|
2158 | multiple-writer-single-reader queue that works in all cases and doesn't |
|
|
2159 | need elaborate support such as pthreads. |
|
|
2160 | |
|
|
2161 | That means that if you want to queue data, you have to provide your own |
|
|
2162 | queue. But at least I can tell you would implement locking around your |
|
|
2163 | queue: |
|
|
2164 | |
|
|
2165 | =over 4 |
|
|
2166 | |
|
|
2167 | =item queueing from a signal handler context |
|
|
2168 | |
|
|
2169 | To implement race-free queueing, you simply add to the queue in the signal |
|
|
2170 | handler but you block the signal handler in the watcher callback. Here is an example that does that for |
|
|
2171 | some fictitiuous SIGUSR1 handler: |
|
|
2172 | |
|
|
2173 | static ev_async mysig; |
|
|
2174 | |
|
|
2175 | static void |
|
|
2176 | sigusr1_handler (void) |
|
|
2177 | { |
|
|
2178 | sometype data; |
|
|
2179 | |
|
|
2180 | // no locking etc. |
|
|
2181 | queue_put (data); |
|
|
2182 | ev_async_send (EV_DEFAULT_ &mysig); |
|
|
2183 | } |
|
|
2184 | |
|
|
2185 | static void |
|
|
2186 | mysig_cb (EV_P_ ev_async *w, int revents) |
|
|
2187 | { |
|
|
2188 | sometype data; |
|
|
2189 | sigset_t block, prev; |
|
|
2190 | |
|
|
2191 | sigemptyset (&block); |
|
|
2192 | sigaddset (&block, SIGUSR1); |
|
|
2193 | sigprocmask (SIG_BLOCK, &block, &prev); |
|
|
2194 | |
|
|
2195 | while (queue_get (&data)) |
|
|
2196 | process (data); |
|
|
2197 | |
|
|
2198 | if (sigismember (&prev, SIGUSR1) |
|
|
2199 | sigprocmask (SIG_UNBLOCK, &block, 0); |
|
|
2200 | } |
|
|
2201 | |
|
|
2202 | (Note: pthreads in theory requires you to use C<pthread_setmask> |
|
|
2203 | instead of C<sigprocmask> when you use threads, but libev doesn't do it |
|
|
2204 | either...). |
|
|
2205 | |
|
|
2206 | =item queueing from a thread context |
|
|
2207 | |
|
|
2208 | The strategy for threads is different, as you cannot (easily) block |
|
|
2209 | threads but you can easily preempt them, so to queue safely you need to |
|
|
2210 | employ a traditional mutex lock, such as in this pthread example: |
|
|
2211 | |
|
|
2212 | static ev_async mysig; |
|
|
2213 | static pthread_mutex_t mymutex = PTHREAD_MUTEX_INITIALIZER; |
|
|
2214 | |
|
|
2215 | static void |
|
|
2216 | otherthread (void) |
|
|
2217 | { |
|
|
2218 | // only need to lock the actual queueing operation |
|
|
2219 | pthread_mutex_lock (&mymutex); |
|
|
2220 | queue_put (data); |
|
|
2221 | pthread_mutex_unlock (&mymutex); |
|
|
2222 | |
|
|
2223 | ev_async_send (EV_DEFAULT_ &mysig); |
|
|
2224 | } |
|
|
2225 | |
|
|
2226 | static void |
|
|
2227 | mysig_cb (EV_P_ ev_async *w, int revents) |
|
|
2228 | { |
|
|
2229 | pthread_mutex_lock (&mymutex); |
|
|
2230 | |
|
|
2231 | while (queue_get (&data)) |
|
|
2232 | process (data); |
|
|
2233 | |
|
|
2234 | pthread_mutex_unlock (&mymutex); |
|
|
2235 | } |
|
|
2236 | |
|
|
2237 | =back |
|
|
2238 | |
|
|
2239 | |
|
|
2240 | =head3 Watcher-Specific Functions and Data Members |
|
|
2241 | |
|
|
2242 | =over 4 |
|
|
2243 | |
|
|
2244 | =item ev_async_init (ev_async *, callback) |
|
|
2245 | |
|
|
2246 | Initialises and configures the async watcher - it has no parameters of any |
|
|
2247 | kind. There is a C<ev_asynd_set> macro, but using it is utterly pointless, |
|
|
2248 | believe me. |
|
|
2249 | |
|
|
2250 | =item ev_async_send (loop, ev_async *) |
|
|
2251 | |
|
|
2252 | Sends/signals/activates the given C<ev_async> watcher, that is, feeds |
|
|
2253 | an C<EV_ASYNC> event on the watcher into the event loop. Unlike |
|
|
2254 | C<ev_feed_event>, this call is safe to do in other threads, signal or |
|
|
2255 | similar contexts (see the dicusssion of C<EV_ATOMIC_T> in the embedding |
|
|
2256 | section below on what exactly this means). |
|
|
2257 | |
|
|
2258 | This call incurs the overhead of a syscall only once per loop iteration, |
|
|
2259 | so while the overhead might be noticable, it doesn't apply to repeated |
|
|
2260 | calls to C<ev_async_send>. |
|
|
2261 | |
|
|
2262 | =back |
|
|
2263 | |
|
|
2264 | |
1870 | =head1 OTHER FUNCTIONS |
2265 | =head1 OTHER FUNCTIONS |
1871 | |
2266 | |
1872 | There are some other functions of possible interest. Described. Here. Now. |
2267 | There are some other functions of possible interest. Described. Here. Now. |
1873 | |
2268 | |
1874 | =over 4 |
2269 | =over 4 |
… | |
… | |
2101 | Example: Define a class with an IO and idle watcher, start one of them in |
2496 | Example: Define a class with an IO and idle watcher, start one of them in |
2102 | the constructor. |
2497 | the constructor. |
2103 | |
2498 | |
2104 | class myclass |
2499 | class myclass |
2105 | { |
2500 | { |
2106 | ev_io io; void io_cb (ev::io &w, int revents); |
2501 | ev::io io; void io_cb (ev::io &w, int revents); |
2107 | ev_idle idle void idle_cb (ev::idle &w, int revents); |
2502 | ev:idle idle void idle_cb (ev::idle &w, int revents); |
2108 | |
2503 | |
2109 | myclass (); |
2504 | myclass (int fd) |
2110 | } |
|
|
2111 | |
|
|
2112 | myclass::myclass (int fd) |
|
|
2113 | { |
2505 | { |
2114 | io .set <myclass, &myclass::io_cb > (this); |
2506 | io .set <myclass, &myclass::io_cb > (this); |
2115 | idle.set <myclass, &myclass::idle_cb> (this); |
2507 | idle.set <myclass, &myclass::idle_cb> (this); |
2116 | |
2508 | |
2117 | io.start (fd, ev::READ); |
2509 | io.start (fd, ev::READ); |
|
|
2510 | } |
2118 | } |
2511 | }; |
|
|
2512 | |
|
|
2513 | |
|
|
2514 | =head1 OTHER LANGUAGE BINDINGS |
|
|
2515 | |
|
|
2516 | Libev does not offer other language bindings itself, but bindings for a |
|
|
2517 | numbe rof languages exist in the form of third-party packages. If you know |
|
|
2518 | any interesting language binding in addition to the ones listed here, drop |
|
|
2519 | me a note. |
|
|
2520 | |
|
|
2521 | =over 4 |
|
|
2522 | |
|
|
2523 | =item Perl |
|
|
2524 | |
|
|
2525 | The EV module implements the full libev API and is actually used to test |
|
|
2526 | libev. EV is developed together with libev. Apart from the EV core module, |
|
|
2527 | there are additional modules that implement libev-compatible interfaces |
|
|
2528 | to C<libadns> (C<EV::ADNS>), C<Net::SNMP> (C<Net::SNMP::EV>) and the |
|
|
2529 | C<libglib> event core (C<Glib::EV> and C<EV::Glib>). |
|
|
2530 | |
|
|
2531 | It can be found and installed via CPAN, its homepage is found at |
|
|
2532 | L<http://software.schmorp.de/pkg/EV>. |
|
|
2533 | |
|
|
2534 | =item Ruby |
|
|
2535 | |
|
|
2536 | Tony Arcieri has written a ruby extension that offers access to a subset |
|
|
2537 | of the libev API and adds filehandle abstractions, asynchronous DNS and |
|
|
2538 | more on top of it. It can be found via gem servers. Its homepage is at |
|
|
2539 | L<http://rev.rubyforge.org/>. |
|
|
2540 | |
|
|
2541 | =item D |
|
|
2542 | |
|
|
2543 | Leandro Lucarella has written a D language binding (F<ev.d>) for libev, to |
|
|
2544 | be found at L<http://git.llucax.com.ar/?p=software/ev.d.git;a=summary>. |
|
|
2545 | |
|
|
2546 | =back |
2119 | |
2547 | |
2120 | |
2548 | |
2121 | =head1 MACRO MAGIC |
2549 | =head1 MACRO MAGIC |
2122 | |
2550 | |
2123 | Libev can be compiled with a variety of options, the most fundamantal |
2551 | Libev can be compiled with a variety of options, the most fundamantal |
… | |
… | |
2297 | runtime if successful). Otherwise no use of the realtime clock option will |
2725 | runtime if successful). Otherwise no use of the realtime clock option will |
2298 | be attempted. This effectively replaces C<gettimeofday> by C<clock_get |
2726 | be attempted. This effectively replaces C<gettimeofday> by C<clock_get |
2299 | (CLOCK_REALTIME, ...)> and will not normally affect correctness. See the |
2727 | (CLOCK_REALTIME, ...)> and will not normally affect correctness. See the |
2300 | note about libraries in the description of C<EV_USE_MONOTONIC>, though. |
2728 | note about libraries in the description of C<EV_USE_MONOTONIC>, though. |
2301 | |
2729 | |
|
|
2730 | =item EV_USE_NANOSLEEP |
|
|
2731 | |
|
|
2732 | If defined to be C<1>, libev will assume that C<nanosleep ()> is available |
|
|
2733 | and will use it for delays. Otherwise it will use C<select ()>. |
|
|
2734 | |
2302 | =item EV_USE_SELECT |
2735 | =item EV_USE_SELECT |
2303 | |
2736 | |
2304 | If undefined or defined to be C<1>, libev will compile in support for the |
2737 | If undefined or defined to be C<1>, libev will compile in support for the |
2305 | C<select>(2) backend. No attempt at autodetection will be done: if no |
2738 | C<select>(2) backend. No attempt at autodetection will be done: if no |
2306 | other method takes over, select will be it. Otherwise the select backend |
2739 | other method takes over, select will be it. Otherwise the select backend |
… | |
… | |
2323 | wants osf handles on win32 (this is the case when the select to |
2756 | wants osf handles on win32 (this is the case when the select to |
2324 | be used is the winsock select). This means that it will call |
2757 | be used is the winsock select). This means that it will call |
2325 | C<_get_osfhandle> on the fd to convert it to an OS handle. Otherwise, |
2758 | C<_get_osfhandle> on the fd to convert it to an OS handle. Otherwise, |
2326 | it is assumed that all these functions actually work on fds, even |
2759 | it is assumed that all these functions actually work on fds, even |
2327 | on win32. Should not be defined on non-win32 platforms. |
2760 | on win32. Should not be defined on non-win32 platforms. |
|
|
2761 | |
|
|
2762 | =item EV_FD_TO_WIN32_HANDLE |
|
|
2763 | |
|
|
2764 | If C<EV_SELECT_IS_WINSOCKET> is enabled, then libev needs a way to map |
|
|
2765 | file descriptors to socket handles. When not defining this symbol (the |
|
|
2766 | default), then libev will call C<_get_osfhandle>, which is usually |
|
|
2767 | correct. In some cases, programs use their own file descriptor management, |
|
|
2768 | in which case they can provide this function to map fds to socket handles. |
2328 | |
2769 | |
2329 | =item EV_USE_POLL |
2770 | =item EV_USE_POLL |
2330 | |
2771 | |
2331 | If defined to be C<1>, libev will compile in support for the C<poll>(2) |
2772 | If defined to be C<1>, libev will compile in support for the C<poll>(2) |
2332 | backend. Otherwise it will be enabled on non-win32 platforms. It |
2773 | backend. Otherwise it will be enabled on non-win32 platforms. It |
… | |
… | |
2366 | |
2807 | |
2367 | If defined to be C<1>, libev will compile in support for the Linux inotify |
2808 | If defined to be C<1>, libev will compile in support for the Linux inotify |
2368 | interface to speed up C<ev_stat> watchers. Its actual availability will |
2809 | interface to speed up C<ev_stat> watchers. Its actual availability will |
2369 | be detected at runtime. |
2810 | be detected at runtime. |
2370 | |
2811 | |
|
|
2812 | =item EV_ATOMIC_T |
|
|
2813 | |
|
|
2814 | Libev requires an integer type (suitable for storing C<0> or C<1>) whose |
|
|
2815 | access is atomic with respect to other threads or signal contexts. No such |
|
|
2816 | type is easily found in the C language, so you can provide your own type |
|
|
2817 | that you know is safe for your purposes. It is used both for signal handler "locking" |
|
|
2818 | as well as for signal and thread safety in C<ev_async> watchers. |
|
|
2819 | |
|
|
2820 | In the absense of this define, libev will use C<sig_atomic_t volatile> |
|
|
2821 | (from F<signal.h>), which is usually good enough on most platforms. |
|
|
2822 | |
2371 | =item EV_H |
2823 | =item EV_H |
2372 | |
2824 | |
2373 | The name of the F<ev.h> header file used to include it. The default if |
2825 | The name of the F<ev.h> header file used to include it. The default if |
2374 | undefined is C<< <ev.h> >> in F<event.h> and C<"ev.h"> in F<ev.c>. This |
2826 | undefined is C<"ev.h"> in F<event.h>, F<ev.c> and F<ev++.h>. This can be |
2375 | can be used to virtually rename the F<ev.h> header file in case of conflicts. |
2827 | used to virtually rename the F<ev.h> header file in case of conflicts. |
2376 | |
2828 | |
2377 | =item EV_CONFIG_H |
2829 | =item EV_CONFIG_H |
2378 | |
2830 | |
2379 | If C<EV_STANDALONE> isn't C<1>, this variable can be used to override |
2831 | If C<EV_STANDALONE> isn't C<1>, this variable can be used to override |
2380 | F<ev.c>'s idea of where to find the F<config.h> file, similarly to |
2832 | F<ev.c>'s idea of where to find the F<config.h> file, similarly to |
2381 | C<EV_H>, above. |
2833 | C<EV_H>, above. |
2382 | |
2834 | |
2383 | =item EV_EVENT_H |
2835 | =item EV_EVENT_H |
2384 | |
2836 | |
2385 | Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea |
2837 | Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea |
2386 | of how the F<event.h> header can be found. |
2838 | of how the F<event.h> header can be found, the default is C<"event.h">. |
2387 | |
2839 | |
2388 | =item EV_PROTOTYPES |
2840 | =item EV_PROTOTYPES |
2389 | |
2841 | |
2390 | If defined to be C<0>, then F<ev.h> will not define any function |
2842 | If defined to be C<0>, then F<ev.h> will not define any function |
2391 | prototypes, but still define all the structs and other symbols. This is |
2843 | prototypes, but still define all the structs and other symbols. This is |
… | |
… | |
2442 | =item EV_FORK_ENABLE |
2894 | =item EV_FORK_ENABLE |
2443 | |
2895 | |
2444 | If undefined or defined to be C<1>, then fork watchers are supported. If |
2896 | If undefined or defined to be C<1>, then fork watchers are supported. If |
2445 | defined to be C<0>, then they are not. |
2897 | defined to be C<0>, then they are not. |
2446 | |
2898 | |
|
|
2899 | =item EV_ASYNC_ENABLE |
|
|
2900 | |
|
|
2901 | If undefined or defined to be C<1>, then async watchers are supported. If |
|
|
2902 | defined to be C<0>, then they are not. |
|
|
2903 | |
2447 | =item EV_MINIMAL |
2904 | =item EV_MINIMAL |
2448 | |
2905 | |
2449 | If you need to shave off some kilobytes of code at the expense of some |
2906 | If you need to shave off some kilobytes of code at the expense of some |
2450 | speed, define this symbol to C<1>. Currently only used for gcc to override |
2907 | speed, define this symbol to C<1>. Currently only used for gcc to override |
2451 | some inlining decisions, saves roughly 30% codesize of amd64. |
2908 | some inlining decisions, saves roughly 30% codesize of amd64. |
… | |
… | |
2457 | than enough. If you need to manage thousands of children you might want to |
2914 | than enough. If you need to manage thousands of children you might want to |
2458 | increase this value (I<must> be a power of two). |
2915 | increase this value (I<must> be a power of two). |
2459 | |
2916 | |
2460 | =item EV_INOTIFY_HASHSIZE |
2917 | =item EV_INOTIFY_HASHSIZE |
2461 | |
2918 | |
2462 | C<ev_staz> watchers use a small hash table to distribute workload by |
2919 | C<ev_stat> watchers use a small hash table to distribute workload by |
2463 | inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>), |
2920 | inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>), |
2464 | usually more than enough. If you need to manage thousands of C<ev_stat> |
2921 | usually more than enough. If you need to manage thousands of C<ev_stat> |
2465 | watchers you might want to increase this value (I<must> be a power of |
2922 | watchers you might want to increase this value (I<must> be a power of |
2466 | two). |
2923 | two). |
2467 | |
2924 | |
… | |
… | |
2563 | |
3020 | |
2564 | =item Starting and stopping timer/periodic watchers: O(log skipped_other_timers) |
3021 | =item Starting and stopping timer/periodic watchers: O(log skipped_other_timers) |
2565 | |
3022 | |
2566 | This means that, when you have a watcher that triggers in one hour and |
3023 | This means that, when you have a watcher that triggers in one hour and |
2567 | there are 100 watchers that would trigger before that then inserting will |
3024 | there are 100 watchers that would trigger before that then inserting will |
2568 | have to skip those 100 watchers. |
3025 | have to skip roughly seven (C<ld 100>) of these watchers. |
2569 | |
3026 | |
2570 | =item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers) |
3027 | =item Changing timer/periodic watchers (by autorepeat or calling again): O(log skipped_other_timers) |
2571 | |
3028 | |
2572 | That means that for changing a timer costs less than removing/adding them |
3029 | That means that changing a timer costs less than removing/adding them |
2573 | as only the relative motion in the event queue has to be paid for. |
3030 | as only the relative motion in the event queue has to be paid for. |
2574 | |
3031 | |
2575 | =item Starting io/check/prepare/idle/signal/child watchers: O(1) |
3032 | =item Starting io/check/prepare/idle/signal/child/fork/async watchers: O(1) |
2576 | |
3033 | |
2577 | These just add the watcher into an array or at the head of a list. |
3034 | These just add the watcher into an array or at the head of a list. |
|
|
3035 | |
2578 | =item Stopping check/prepare/idle watchers: O(1) |
3036 | =item Stopping check/prepare/idle/fork/async watchers: O(1) |
2579 | |
3037 | |
2580 | =item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE)) |
3038 | =item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE)) |
2581 | |
3039 | |
2582 | These watchers are stored in lists then need to be walked to find the |
3040 | These watchers are stored in lists then need to be walked to find the |
2583 | correct watcher to remove. The lists are usually short (you don't usually |
3041 | correct watcher to remove. The lists are usually short (you don't usually |
2584 | have many watchers waiting for the same fd or signal). |
3042 | have many watchers waiting for the same fd or signal). |
2585 | |
3043 | |
2586 | =item Finding the next timer per loop iteration: O(1) |
3044 | =item Finding the next timer in each loop iteration: O(1) |
|
|
3045 | |
|
|
3046 | By virtue of using a binary heap, the next timer is always found at the |
|
|
3047 | beginning of the storage array. |
2587 | |
3048 | |
2588 | =item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd) |
3049 | =item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd) |
2589 | |
3050 | |
2590 | A change means an I/O watcher gets started or stopped, which requires |
3051 | A change means an I/O watcher gets started or stopped, which requires |
2591 | libev to recalculate its status (and possibly tell the kernel). |
3052 | libev to recalculate its status (and possibly tell the kernel, depending |
|
|
3053 | on backend and wether C<ev_io_set> was used). |
2592 | |
3054 | |
2593 | =item Activating one watcher: O(1) |
3055 | =item Activating one watcher (putting it into the pending state): O(1) |
2594 | |
3056 | |
2595 | =item Priority handling: O(number_of_priorities) |
3057 | =item Priority handling: O(number_of_priorities) |
2596 | |
3058 | |
2597 | Priorities are implemented by allocating some space for each |
3059 | Priorities are implemented by allocating some space for each |
2598 | priority. When doing priority-based operations, libev usually has to |
3060 | priority. When doing priority-based operations, libev usually has to |
2599 | linearly search all the priorities. |
3061 | linearly search all the priorities, but starting/stopping and activating |
|
|
3062 | watchers becomes O(1) w.r.t. priority handling. |
|
|
3063 | |
|
|
3064 | =item Sending an ev_async: O(1) |
|
|
3065 | |
|
|
3066 | =item Processing ev_async_send: O(number_of_async_watchers) |
|
|
3067 | |
|
|
3068 | =item Processing signals: O(max_signal_number) |
|
|
3069 | |
|
|
3070 | Sending involves a syscall I<iff> there were no other C<ev_async_send> |
|
|
3071 | calls in the current loop iteration. Checking for async and signal events |
|
|
3072 | involves iterating over all running async watchers or all signal numbers. |
2600 | |
3073 | |
2601 | =back |
3074 | =back |
2602 | |
3075 | |
2603 | |
3076 | |
|
|
3077 | =head1 Win32 platform limitations and workarounds |
|
|
3078 | |
|
|
3079 | Win32 doesn't support any of the standards (e.g. POSIX) that libev |
|
|
3080 | requires, and its I/O model is fundamentally incompatible with the POSIX |
|
|
3081 | model. Libev still offers limited functionality on this platform in |
|
|
3082 | the form of the C<EVBACKEND_SELECT> backend, and only supports socket |
|
|
3083 | descriptors. This only applies when using Win32 natively, not when using |
|
|
3084 | e.g. cygwin. |
|
|
3085 | |
|
|
3086 | There is no supported compilation method available on windows except |
|
|
3087 | embedding it into other applications. |
|
|
3088 | |
|
|
3089 | Due to the many, low, and arbitrary limits on the win32 platform and the |
|
|
3090 | abysmal performance of winsockets, using a large number of sockets is not |
|
|
3091 | recommended (and not reasonable). If your program needs to use more than |
|
|
3092 | a hundred or so sockets, then likely it needs to use a totally different |
|
|
3093 | implementation for windows, as libev offers the POSIX model, which cannot |
|
|
3094 | be implemented efficiently on windows (microsoft monopoly games). |
|
|
3095 | |
|
|
3096 | =over 4 |
|
|
3097 | |
|
|
3098 | =item The winsocket select function |
|
|
3099 | |
|
|
3100 | The winsocket C<select> function doesn't follow POSIX in that it requires |
|
|
3101 | socket I<handles> and not socket I<file descriptors>. This makes select |
|
|
3102 | very inefficient, and also requires a mapping from file descriptors |
|
|
3103 | to socket handles. See the discussion of the C<EV_SELECT_USE_FD_SET>, |
|
|
3104 | C<EV_SELECT_IS_WINSOCKET> and C<EV_FD_TO_WIN32_HANDLE> preprocessor |
|
|
3105 | symbols for more info. |
|
|
3106 | |
|
|
3107 | The configuration for a "naked" win32 using the microsoft runtime |
|
|
3108 | libraries and raw winsocket select is: |
|
|
3109 | |
|
|
3110 | #define EV_USE_SELECT 1 |
|
|
3111 | #define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */ |
|
|
3112 | |
|
|
3113 | Note that winsockets handling of fd sets is O(n), so you can easily get a |
|
|
3114 | complexity in the O(n²) range when using win32. |
|
|
3115 | |
|
|
3116 | =item Limited number of file descriptors |
|
|
3117 | |
|
|
3118 | Windows has numerous arbitrary (and low) limits on things. Early versions |
|
|
3119 | of winsocket's select only supported waiting for a max. of C<64> handles |
|
|
3120 | (probably owning to the fact that all windows kernels can only wait for |
|
|
3121 | C<64> things at the same time internally; microsoft recommends spawning a |
|
|
3122 | chain of threads and wait for 63 handles and the previous thread in each). |
|
|
3123 | |
|
|
3124 | Newer versions support more handles, but you need to define C<FD_SETSIZE> |
|
|
3125 | to some high number (e.g. C<2048>) before compiling the winsocket select |
|
|
3126 | call (which might be in libev or elsewhere, for example, perl does its own |
|
|
3127 | select emulation on windows). |
|
|
3128 | |
|
|
3129 | Another limit is the number of file descriptors in the microsoft runtime |
|
|
3130 | libraries, which by default is C<64> (there must be a hidden I<64> fetish |
|
|
3131 | or something like this inside microsoft). You can increase this by calling |
|
|
3132 | C<_setmaxstdio>, which can increase this limit to C<2048> (another |
|
|
3133 | arbitrary limit), but is broken in many versions of the microsoft runtime |
|
|
3134 | libraries. |
|
|
3135 | |
|
|
3136 | This might get you to about C<512> or C<2048> sockets (depending on |
|
|
3137 | windows version and/or the phase of the moon). To get more, you need to |
|
|
3138 | wrap all I/O functions and provide your own fd management, but the cost of |
|
|
3139 | calling select (O(n²)) will likely make this unworkable. |
|
|
3140 | |
|
|
3141 | =back |
|
|
3142 | |
|
|
3143 | |
2604 | =head1 AUTHOR |
3144 | =head1 AUTHOR |
2605 | |
3145 | |
2606 | Marc Lehmann <libev@schmorp.de>. |
3146 | Marc Lehmann <libev@schmorp.de>. |
2607 | |
3147 | |