… | |
… | |
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 | |
|
|
14 | // every watcher type has its own typedef'd struct |
|
|
15 | // with the name ev_<type> |
13 | ev_io stdin_watcher; |
16 | ev_io stdin_watcher; |
14 | ev_timer timeout_watcher; |
17 | ev_timer timeout_watcher; |
15 | |
18 | |
|
|
19 | // all watcher callbacks have a similar signature |
16 | /* called when data readable on stdin */ |
20 | // this callback is called when data is readable on stdin |
17 | static void |
21 | static void |
18 | stdin_cb (EV_P_ struct ev_io *w, int revents) |
22 | stdin_cb (EV_P_ struct ev_io *w, int revents) |
19 | { |
23 | { |
20 | /* puts ("stdin ready"); */ |
24 | puts ("stdin ready"); |
21 | ev_io_stop (EV_A_ w); /* just a syntax example */ |
25 | // for one-shot events, one must manually stop the watcher |
22 | ev_unloop (EV_A_ EVUNLOOP_ALL); /* leave all loop calls */ |
26 | // with its corresponding stop function. |
|
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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 |
|
|
39 | ev_unloop (EV_A_ EVUNLOOP_ONE); |
30 | } |
40 | } |
31 | |
41 | |
32 | int |
42 | int |
33 | main (void) |
43 | main (void) |
34 | { |
44 | { |
|
|
45 | // use the default event loop unless you have special needs |
35 | struct ev_loop *loop = ev_default_loop (0); |
46 | struct ev_loop *loop = ev_default_loop (0); |
36 | |
47 | |
37 | /* initialise an io watcher, then start it */ |
48 | // initialise an io watcher, then start it |
|
|
49 | // this one will watch for stdin to become readable |
38 | ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ); |
50 | ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ); |
39 | ev_io_start (loop, &stdin_watcher); |
51 | ev_io_start (loop, &stdin_watcher); |
40 | |
52 | |
|
|
53 | // initialise a timer watcher, then start it |
41 | /* simple non-repeating 5.5 second timeout */ |
54 | // simple non-repeating 5.5 second timeout |
42 | ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.); |
55 | ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.); |
43 | ev_timer_start (loop, &timeout_watcher); |
56 | ev_timer_start (loop, &timeout_watcher); |
44 | |
57 | |
45 | /* loop till timeout or data ready */ |
58 | // now wait for events to arrive |
46 | ev_loop (loop, 0); |
59 | ev_loop (loop, 0); |
47 | |
60 | |
|
|
61 | // unloop was called, so exit |
48 | return 0; |
62 | return 0; |
49 | } |
63 | } |
50 | |
64 | |
51 | =head1 DESCRIPTION |
65 | =head1 DESCRIPTION |
52 | |
66 | |
53 | The newest version of this document is also available as a html-formatted |
67 | The newest version of this document is also available as an html-formatted |
54 | web page you might find easier to navigate when reading it for the first |
68 | web page you might find easier to navigate when reading it for the first |
55 | time: L<http://cvs.schmorp.de/libev/ev.html>. |
69 | time: L<http://cvs.schmorp.de/libev/ev.html>. |
56 | |
70 | |
57 | Libev is an event loop: you register interest in certain events (such as a |
71 | Libev is an event loop: you register interest in certain events (such as a |
58 | file descriptor being readable or a timeout occuring), and it will manage |
72 | file descriptor being readable or a timeout occurring), and it will manage |
59 | these event sources and provide your program with events. |
73 | these event sources and provide your program with events. |
60 | |
74 | |
61 | To do this, it must take more or less complete control over your process |
75 | To do this, it must take more or less complete control over your process |
62 | (or thread) by executing the I<event loop> handler, and will then |
76 | (or thread) by executing the I<event loop> handler, and will then |
63 | communicate events via a callback mechanism. |
77 | communicate events via a callback mechanism. |
… | |
… | |
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 |
102 | to the C<double> type in C, and when you need to do any calculations on |
117 | to the C<double> type in C, and when you need to do any calculations on |
103 | it, you should treat it as such. |
118 | it, you should treat it as some floatingpoint value. Unlike the name |
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119 | component C<stamp> might indicate, it is also used for time differences |
|
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120 | throughout libev. |
104 | |
121 | |
105 | =head1 GLOBAL FUNCTIONS |
122 | =head1 GLOBAL FUNCTIONS |
106 | |
123 | |
107 | These functions can be called anytime, even before initialising the |
124 | These functions can be called anytime, even before initialising the |
108 | library in any way. |
125 | library in any way. |
… | |
… | |
112 | =item ev_tstamp ev_time () |
129 | =item ev_tstamp ev_time () |
113 | |
130 | |
114 | 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 |
115 | 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 |
116 | you actually want to know. |
133 | you actually want to know. |
|
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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 ()>. |
117 | |
140 | |
118 | =item int ev_version_major () |
141 | =item int ev_version_major () |
119 | |
142 | |
120 | =item int ev_version_minor () |
143 | =item int ev_version_minor () |
121 | |
144 | |
… | |
… | |
252 | flags. If that is troubling you, check C<ev_backend ()> afterwards). |
275 | flags. If that is troubling you, check C<ev_backend ()> afterwards). |
253 | |
276 | |
254 | 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 |
255 | function. |
278 | function. |
256 | |
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 | |
257 | 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 |
258 | 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>). |
259 | |
289 | |
260 | The following flags are supported: |
290 | The following flags are supported: |
261 | |
291 | |
… | |
… | |
282 | enabling this flag. |
312 | enabling this flag. |
283 | |
313 | |
284 | 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, |
285 | 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 |
286 | 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 |
287 | 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 |
288 | 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 |
289 | C<pthread_atfork> which is even faster). |
319 | C<pthread_atfork> which is even faster). |
290 | |
320 | |
291 | 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 |
292 | 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 |
293 | flag. |
323 | flag. |
… | |
… | |
298 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
328 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
299 | |
329 | |
300 | 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 |
301 | 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, |
302 | 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 |
303 | 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 |
304 | 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 | |
|
|
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. |
305 | |
342 | |
306 | =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) |
307 | |
344 | |
308 | 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 |
309 | 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 |
310 | 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 |
311 | 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. |
312 | |
351 | |
313 | =item C<EVBACKEND_EPOLL> (value 4, Linux) |
352 | =item C<EVBACKEND_EPOLL> (value 4, Linux) |
314 | |
353 | |
315 | 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, |
316 | but it scales phenomenally better. While poll and select usually scale like |
355 | but it scales phenomenally better. While poll and select usually scale |
317 | O(total_fds) where n is the total number of fds (or the highest fd), epoll scales |
356 | like O(total_fds) where n is the total number of fds (or the highest fd), |
318 | either O(1) or O(active_fds). |
357 | epoll scales either O(1) or O(active_fds). The epoll design has a number |
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358 | of shortcomings, such as silently dropping events in some hard-to-detect |
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359 | cases and rewiring a syscall per fd change, no fork support and bad |
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360 | support for dup. |
319 | |
361 | |
320 | While stopping and starting an I/O watcher in the same iteration will |
362 | While stopping, setting and starting an I/O watcher in the same iteration |
321 | 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 |
322 | (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 |
323 | best to avoid that. Also, dup()ed file descriptors might not work very |
365 | best to avoid that. Also, C<dup ()>'ed file descriptors might not work |
324 | well if you register events for both fds. |
366 | very well if you register events for both fds. |
325 | |
367 | |
326 | Please note that epoll sometimes generates spurious notifications, so you |
368 | Please note that epoll sometimes generates spurious notifications, so you |
327 | 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 |
328 | (or space) is available. |
370 | (or space) is available. |
329 | |
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 | |
330 | =item C<EVBACKEND_KQUEUE> (value 8, most BSD clones) |
379 | =item C<EVBACKEND_KQUEUE> (value 8, most BSD clones) |
331 | |
380 | |
332 | 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 |
333 | was broken on all BSDs except NetBSD (usually it doesn't work with |
382 | was broken on all BSDs except NetBSD (usually it doesn't work reliably |
334 | anything but sockets and pipes, except on Darwin, where of course its |
383 | with anything but sockets and pipes, except on Darwin, where of course |
335 | completely useless). For this reason its not being "autodetected" |
384 | it's completely useless). For this reason it's not being "autodetected" |
336 | 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 |
337 | C<EVBACKEND_KQUEUE>). |
386 | C<EVBACKEND_KQUEUE>) or libev was compiled on a known-to-be-good (-enough) |
|
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387 | system like NetBSD. |
|
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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. |
338 | |
392 | |
339 | 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 |
340 | kernel is more efficient (which says nothing about its actual speed, of |
394 | kernel is more efficient (which says nothing about its actual speed, of |
341 | course). While starting and stopping an I/O watcher does not cause an |
395 | course). While stopping, setting and starting an I/O watcher does never |
342 | extra syscall as with epoll, it still adds up to four event changes per |
396 | cause an extra syscall as with C<EVBACKEND_EPOLL>, it still adds up to |
343 | incident, so its best to avoid that. |
397 | two event changes per incident, support for C<fork ()> is very bad and it |
|
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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. |
|
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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. |
344 | |
408 | |
345 | =item C<EVBACKEND_DEVPOLL> (value 16, Solaris 8) |
409 | =item C<EVBACKEND_DEVPOLL> (value 16, Solaris 8) |
346 | |
410 | |
347 | 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. |
348 | |
415 | |
349 | =item C<EVBACKEND_PORT> (value 32, Solaris 10) |
416 | =item C<EVBACKEND_PORT> (value 32, Solaris 10) |
350 | |
417 | |
351 | This uses the Solaris 10 port mechanism. As with everything on Solaris, |
418 | This uses the Solaris 10 event port mechanism. As with everything on Solaris, |
352 | 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)). |
353 | |
420 | |
354 | Please note that solaris ports can result in a lot of spurious |
421 | Please note that solaris event ports can deliver a lot of spurious |
355 | 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 |
356 | blocking when no data (or space) is available. |
423 | blocking when no data (or space) is available. |
|
|
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 |
|
|
427 | descriptors a "slow" C<EVBACKEND_SELECT> or C<EVBACKEND_POLL> backend |
|
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428 | might perform better. |
|
|
429 | |
|
|
430 | On the positive side, ignoring the spurious readyness notifications, this |
|
|
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. |
357 | |
433 | |
358 | =item C<EVBACKEND_ALL> |
434 | =item C<EVBACKEND_ALL> |
359 | |
435 | |
360 | 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 |
361 | 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 |
362 | C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>. |
438 | C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>. |
363 | |
439 | |
|
|
440 | It is definitely not recommended to use this flag. |
|
|
441 | |
364 | =back |
442 | =back |
365 | |
443 | |
366 | 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 |
367 | 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 |
368 | specified, most compiled-in backend will be tried, usually in reverse |
446 | specified, all backends in C<ev_recommended_backends ()> will be tried. |
369 | order of their flag values :) |
|
|
370 | |
447 | |
371 | The most typical usage is like this: |
448 | The most typical usage is like this: |
372 | |
449 | |
373 | if (!ev_default_loop (0)) |
450 | if (!ev_default_loop (0)) |
374 | fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?"); |
451 | fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?"); |
… | |
… | |
402 | Destroys the default loop again (frees all memory and kernel state |
479 | Destroys the default loop again (frees all memory and kernel state |
403 | etc.). None of the active event watchers will be stopped in the normal |
480 | etc.). None of the active event watchers will be stopped in the normal |
404 | sense, so e.g. C<ev_is_active> might still return true. It is your |
481 | sense, so e.g. C<ev_is_active> might still return true. It is your |
405 | responsibility to either stop all watchers cleanly yoursef I<before> |
482 | responsibility to either stop all watchers cleanly yoursef I<before> |
406 | calling this function, or cope with the fact afterwards (which is usually |
483 | calling this function, or cope with the fact afterwards (which is usually |
407 | the easiest thing, youc na just ignore the watchers and/or C<free ()> them |
484 | the easiest thing, you can just ignore the watchers and/or C<free ()> them |
408 | for example). |
485 | for example). |
|
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486 | |
|
|
487 | Note that certain global state, such as signal state, will not be freed by |
|
|
488 | this function, and related watchers (such as signal and child watchers) |
|
|
489 | would need to be stopped manually. |
|
|
490 | |
|
|
491 | In general it is not advisable to call this function except in the |
|
|
492 | rare occasion where you really need to free e.g. the signal handling |
|
|
493 | pipe fds. If you need dynamically allocated loops it is better to use |
|
|
494 | C<ev_loop_new> and C<ev_loop_destroy>). |
409 | |
495 | |
410 | =item ev_loop_destroy (loop) |
496 | =item ev_loop_destroy (loop) |
411 | |
497 | |
412 | 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 |
413 | earlier call to C<ev_loop_new>. |
499 | earlier call to C<ev_loop_new>. |
414 | |
500 | |
415 | =item ev_default_fork () |
501 | =item ev_default_fork () |
416 | |
502 | |
|
|
503 | This function sets a flag that causes subsequent C<ev_loop> iterations |
417 | This function reinitialises the kernel state for backends that have |
504 | to reinitialise the kernel state for backends that have one. Despite the |
418 | 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 |
419 | 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 |
420 | again makes little sense). |
507 | sense). You I<must> call it in the child before using any of the libev |
|
|
508 | functions, and it will only take effect at the next C<ev_loop> iteration. |
421 | |
509 | |
422 | 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 |
423 | 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 |
424 | fork+exec, you don't have to call it. |
512 | you just fork+exec, you don't have to call it at all. |
425 | |
513 | |
426 | 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 |
427 | 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 |
428 | quite nicely into a call to C<pthread_atfork>: |
516 | quite nicely into a call to C<pthread_atfork>: |
429 | |
517 | |
430 | pthread_atfork (0, 0, ev_default_fork); |
518 | pthread_atfork (0, 0, ev_default_fork); |
431 | |
519 | |
432 | At the moment, C<EVBACKEND_SELECT> and C<EVBACKEND_POLL> are safe to use |
|
|
433 | without calling this function, so if you force one of those backends you |
|
|
434 | do not need to care. |
|
|
435 | |
|
|
436 | =item ev_loop_fork (loop) |
520 | =item ev_loop_fork (loop) |
437 | |
521 | |
438 | 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 |
439 | 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 |
440 | 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. |
441 | |
529 | |
442 | =item unsigned int ev_loop_count (loop) |
530 | =item unsigned int ev_loop_count (loop) |
443 | |
531 | |
444 | 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 |
445 | 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 |
… | |
… | |
458 | |
546 | |
459 | Returns the current "event loop time", which is the time the event loop |
547 | Returns the current "event loop time", which is the time the event loop |
460 | received events and started processing them. This timestamp does not |
548 | received events and started processing them. This timestamp does not |
461 | change as long as callbacks are being processed, and this is also the base |
549 | change as long as callbacks are being processed, and this is also the base |
462 | time used for relative timers. You can treat it as the timestamp of the |
550 | time used for relative timers. You can treat it as the timestamp of the |
463 | event occuring (or more correctly, libev finding out about it). |
551 | event occurring (or more correctly, libev finding out about it). |
464 | |
552 | |
465 | =item ev_loop (loop, int flags) |
553 | =item ev_loop (loop, int flags) |
466 | |
554 | |
467 | Finally, this is it, the event handler. This function usually is called |
555 | Finally, this is it, the event handler. This function usually is called |
468 | after you initialised all your watchers and you want to start handling |
556 | after you initialised all your watchers and you want to start handling |
… | |
… | |
490 | usually a better approach for this kind of thing. |
578 | usually a better approach for this kind of thing. |
491 | |
579 | |
492 | Here are the gory details of what C<ev_loop> does: |
580 | Here are the gory details of what C<ev_loop> does: |
493 | |
581 | |
494 | - Before the first iteration, call any pending watchers. |
582 | - Before the first iteration, call any pending watchers. |
495 | * If there are no active watchers (reference count is zero), return. |
583 | * If EVFLAG_FORKCHECK was used, check for a fork. |
496 | - 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. |
497 | - If we have been forked, recreate the kernel state. |
586 | - If we have been forked, recreate the kernel state. |
498 | - Update the kernel state with all outstanding changes. |
587 | - Update the kernel state with all outstanding changes. |
499 | - Update the "event loop time". |
588 | - Update the "event loop time". |
500 | - 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. |
501 | - Block the process, waiting for any events. |
593 | - Block the process, waiting for any events. |
502 | - Queue all outstanding I/O (fd) events. |
594 | - Queue all outstanding I/O (fd) events. |
503 | - Update the "event loop time" and do time jump handling. |
595 | - Update the "event loop time" and do time jump handling. |
504 | - Queue all outstanding timers. |
596 | - Queue all outstanding timers. |
505 | - Queue all outstanding periodics. |
597 | - Queue all outstanding periodics. |
506 | - If no events are pending now, queue all idle watchers. |
598 | - If no events are pending now, queue all idle watchers. |
507 | - Queue all check watchers. |
599 | - Queue all check watchers. |
508 | - 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). |
509 | 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 |
510 | be handled here by queueing them when their watcher gets executed. |
602 | be handled here by queueing them when their watcher gets executed. |
511 | - 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 |
512 | were used, return, otherwise continue with step *. |
604 | were used, or there are no active watchers, return, otherwise |
|
|
605 | continue with step *. |
513 | |
606 | |
514 | 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 |
515 | anymore. |
608 | anymore. |
516 | |
609 | |
517 | ... queue jobs here, make sure they register event watchers as long |
610 | ... queue jobs here, make sure they register event watchers as long |
518 | ... 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..) |
519 | ev_loop (my_loop, 0); |
612 | ev_loop (my_loop, 0); |
… | |
… | |
523 | |
616 | |
524 | 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 |
525 | 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 |
526 | 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 |
527 | 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. |
528 | |
623 | |
529 | =item ev_ref (loop) |
624 | =item ev_ref (loop) |
530 | |
625 | |
531 | =item ev_unref (loop) |
626 | =item ev_unref (loop) |
532 | |
627 | |
… | |
… | |
537 | 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 |
538 | 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 |
539 | 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 |
540 | 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 |
541 | 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 |
542 | 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). |
543 | |
640 | |
544 | 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> |
545 | running when nothing else is active. |
642 | running when nothing else is active. |
546 | |
643 | |
547 | struct ev_signal exitsig; |
644 | struct ev_signal exitsig; |
… | |
… | |
551 | |
648 | |
552 | Example: For some weird reason, unregister the above signal handler again. |
649 | Example: For some weird reason, unregister the above signal handler again. |
553 | |
650 | |
554 | ev_ref (loop); |
651 | ev_ref (loop); |
555 | 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. |
556 | |
689 | |
557 | =back |
690 | =back |
558 | |
691 | |
559 | |
692 | |
560 | =head1 ANATOMY OF A WATCHER |
693 | =head1 ANATOMY OF A WATCHER |
… | |
… | |
659 | |
792 | |
660 | =item C<EV_FORK> |
793 | =item C<EV_FORK> |
661 | |
794 | |
662 | 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 |
663 | 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>). |
664 | |
801 | |
665 | =item C<EV_ERROR> |
802 | =item C<EV_ERROR> |
666 | |
803 | |
667 | 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 |
668 | happen because the watcher could not be properly started because libev |
805 | happen because the watcher could not be properly started because libev |
… | |
… | |
886 | 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 |
887 | 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 |
888 | 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 |
889 | required if you know what you are doing). |
1026 | required if you know what you are doing). |
890 | |
1027 | |
891 | You have to be careful with dup'ed file descriptors, though. Some backends |
|
|
892 | (the linux epoll backend is a notable example) cannot handle dup'ed file |
|
|
893 | descriptors correctly if you register interest in two or more fds pointing |
|
|
894 | to the same underlying file/socket/etc. description (that is, they share |
|
|
895 | the same underlying "file open"). |
|
|
896 | |
|
|
897 | 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 |
898 | (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 |
899 | C<EVBACKEND_POLL>). |
1030 | C<EVBACKEND_POLL>). |
900 | |
1031 | |
901 | 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 |
… | |
… | |
913 | such as poll (fortunately in our Xlib example, Xlib already does this on |
1044 | such as poll (fortunately in our Xlib example, Xlib already does this on |
914 | its own, so its quite safe to use). |
1045 | its own, so its quite safe to use). |
915 | |
1046 | |
916 | =head3 The special problem of disappearing file descriptors |
1047 | =head3 The special problem of disappearing file descriptors |
917 | |
1048 | |
918 | Some backends (e.g kqueue, epoll) need to be told about closing a file |
1049 | Some backends (e.g. kqueue, epoll) need to be told about closing a file |
919 | descriptor (either by calling C<close> explicitly or by any other means, |
1050 | descriptor (either by calling C<close> explicitly or by any other means, |
920 | such as C<dup>). The reason is that you register interest in some file |
1051 | such as C<dup>). The reason is that you register interest in some file |
921 | descriptor, but when it goes away, the operating system will silently drop |
1052 | descriptor, but when it goes away, the operating system will silently drop |
922 | this interest. If another file descriptor with the same number then is |
1053 | this interest. If another file descriptor with the same number then is |
923 | registered with libev, there is no efficient way to see that this is, in |
1054 | registered with libev, there is no efficient way to see that this is, in |
… | |
… | |
932 | |
1063 | |
933 | This is how one would do it normally anyway, the important point is that |
1064 | This is how one would do it normally anyway, the important point is that |
934 | the libev application should not optimise around libev but should leave |
1065 | the libev application should not optimise around libev but should leave |
935 | optimisations to libev. |
1066 | optimisations to libev. |
936 | |
1067 | |
|
|
1068 | =head3 The special problem of dup'ed file descriptors |
|
|
1069 | |
|
|
1070 | Some backends (e.g. epoll), cannot register events for file descriptors, |
|
|
1071 | but only events for the underlying file descriptions. That means when you |
|
|
1072 | have C<dup ()>'ed file descriptors or weirder constellations, and register |
|
|
1073 | events for them, only one file descriptor might actually receive events. |
|
|
1074 | |
|
|
1075 | There is no workaround possible except not registering events |
|
|
1076 | for potentially C<dup ()>'ed file descriptors, or to resort to |
|
|
1077 | C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>. |
|
|
1078 | |
|
|
1079 | =head3 The special problem of fork |
|
|
1080 | |
|
|
1081 | Some backends (epoll, kqueue) do not support C<fork ()> at all or exhibit |
|
|
1082 | useless behaviour. Libev fully supports fork, but needs to be told about |
|
|
1083 | it in the child. |
|
|
1084 | |
|
|
1085 | To support fork in your programs, you either have to call |
|
|
1086 | C<ev_default_fork ()> or C<ev_loop_fork ()> after a fork in the child, |
|
|
1087 | enable C<EVFLAG_FORKCHECK>, or resort to C<EVBACKEND_SELECT> or |
|
|
1088 | C<EVBACKEND_POLL>. |
|
|
1089 | |
937 | |
1090 | |
938 | =head3 Watcher-Specific Functions |
1091 | =head3 Watcher-Specific Functions |
939 | |
1092 | |
940 | =over 4 |
1093 | =over 4 |
941 | |
1094 | |
… | |
… | |
954 | =item int events [read-only] |
1107 | =item int events [read-only] |
955 | |
1108 | |
956 | The events being watched. |
1109 | The events being watched. |
957 | |
1110 | |
958 | =back |
1111 | =back |
|
|
1112 | |
|
|
1113 | =head3 Examples |
959 | |
1114 | |
960 | 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 |
961 | 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 |
962 | attempt to read a whole line in the callback. |
1117 | attempt to read a whole line in the callback. |
963 | |
1118 | |
… | |
… | |
1016 | 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 |
1017 | 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 |
1018 | 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 |
1019 | timer will not fire more than once per event loop iteration. |
1174 | timer will not fire more than once per event loop iteration. |
1020 | |
1175 | |
1021 | =item ev_timer_again (loop) |
1176 | =item ev_timer_again (loop, ev_timer *) |
1022 | |
1177 | |
1023 | 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 |
1024 | repeating. The exact semantics are: |
1179 | repeating. The exact semantics are: |
1025 | |
1180 | |
1026 | If the timer is pending, its pending status is cleared. |
1181 | If the timer is pending, its pending status is cleared. |
… | |
… | |
1061 | 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), |
1062 | which is also when any modifications are taken into account. |
1217 | which is also when any modifications are taken into account. |
1063 | |
1218 | |
1064 | =back |
1219 | =back |
1065 | |
1220 | |
|
|
1221 | =head3 Examples |
|
|
1222 | |
1066 | Example: Create a timer that fires after 60 seconds. |
1223 | Example: Create a timer that fires after 60 seconds. |
1067 | |
1224 | |
1068 | static void |
1225 | static void |
1069 | 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) |
1070 | { |
1227 | { |
… | |
… | |
1133 | 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 |
1134 | 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, |
1135 | 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 |
1136 | system time reaches or surpasses this time. |
1293 | system time reaches or surpasses this time. |
1137 | |
1294 | |
1138 | =item * non-repeating interval timer (at = offset, interval > 0, reschedule_cb = 0) |
1295 | =item * repeating interval timer (at = offset, interval > 0, reschedule_cb = 0) |
1139 | |
1296 | |
1140 | 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 |
1141 | 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) |
1142 | and then repeat, regardless of any time jumps. |
1299 | and then repeat, regardless of any time jumps. |
1143 | |
1300 | |
… | |
… | |
1220 | |
1377 | |
1221 | The current reschedule callback, or C<0>, if this functionality is |
1378 | The current reschedule callback, or C<0>, if this functionality is |
1222 | switched off. Can be changed any time, but changes only take effect when |
1379 | switched off. Can be changed any time, but changes only take effect when |
1223 | the periodic timer fires or C<ev_periodic_again> is being called. |
1380 | the periodic timer fires or C<ev_periodic_again> is being called. |
1224 | |
1381 | |
|
|
1382 | =item ev_tstamp at [read-only] |
|
|
1383 | |
|
|
1384 | When active, contains the absolute time that the watcher is supposed to |
|
|
1385 | trigger next. |
|
|
1386 | |
1225 | =back |
1387 | =back |
|
|
1388 | |
|
|
1389 | =head3 Examples |
1226 | |
1390 | |
1227 | Example: Call a callback every hour, or, more precisely, whenever the |
1391 | Example: Call a callback every hour, or, more precisely, whenever the |
1228 | system clock is divisible by 3600. The callback invocation times have |
1392 | system clock is divisible by 3600. The callback invocation times have |
1229 | potentially a lot of jittering, but good long-term stability. |
1393 | potentially a lot of jittering, but good long-term stability. |
1230 | |
1394 | |
… | |
… | |
1270 | 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 |
1271 | 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 |
1272 | 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 |
1273 | SIG_DFL (regardless of what it was set to before). |
1437 | SIG_DFL (regardless of what it was set to before). |
1274 | |
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 | |
1275 | =head3 Watcher-Specific Functions and Data Members |
1445 | =head3 Watcher-Specific Functions and Data Members |
1276 | |
1446 | |
1277 | =over 4 |
1447 | =over 4 |
1278 | |
1448 | |
1279 | =item ev_signal_init (ev_signal *, callback, int signum) |
1449 | =item ev_signal_init (ev_signal *, callback, int signum) |
… | |
… | |
1287 | |
1457 | |
1288 | The signal the watcher watches out for. |
1458 | The signal the watcher watches out for. |
1289 | |
1459 | |
1290 | =back |
1460 | =back |
1291 | |
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 | |
1292 | |
1476 | |
1293 | =head2 C<ev_child> - watch out for process status changes |
1477 | =head2 C<ev_child> - watch out for process status changes |
1294 | |
1478 | |
1295 | 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 |
1296 | 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. |
1297 | |
1506 | |
1298 | =head3 Watcher-Specific Functions and Data Members |
1507 | =head3 Watcher-Specific Functions and Data Members |
1299 | |
1508 | |
1300 | =over 4 |
1509 | =over 4 |
1301 | |
1510 | |
1302 | =item ev_child_init (ev_child *, callback, int pid) |
1511 | =item ev_child_init (ev_child *, callback, int pid, int trace) |
1303 | |
1512 | |
1304 | =item ev_child_set (ev_child *, int pid) |
1513 | =item ev_child_set (ev_child *, int pid, int trace) |
1305 | |
1514 | |
1306 | 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 |
1307 | 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 |
1308 | 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 |
1309 | 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 |
1310 | 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 |
1311 | 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). |
1312 | |
1523 | |
1313 | =item int pid [read-only] |
1524 | =item int pid [read-only] |
1314 | |
1525 | |
1315 | 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. |
1316 | |
1527 | |
… | |
… | |
1323 | 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 |
1324 | C<waitpid> and C<sys/wait.h> documentation for details). |
1535 | C<waitpid> and C<sys/wait.h> documentation for details). |
1325 | |
1536 | |
1326 | =back |
1537 | =back |
1327 | |
1538 | |
1328 | 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; |
1329 | |
1545 | |
1330 | static void |
1546 | static void |
1331 | sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) |
1547 | child_cb (EV_P_ struct ev_child *w, int revents) |
1332 | { |
1548 | { |
1333 | 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); |
1334 | } |
1551 | } |
1335 | |
1552 | |
1336 | struct ev_signal signal_watcher; |
1553 | pid_t pid = fork (); |
1337 | ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
1554 | |
1338 | 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 | } |
1339 | |
1567 | |
1340 | |
1568 | |
1341 | =head2 C<ev_stat> - did the file attributes just change? |
1569 | =head2 C<ev_stat> - did the file attributes just change? |
1342 | |
1570 | |
1343 | 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 |
… | |
… | |
1372 | 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 |
1373 | 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 |
1374 | 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 |
1375 | polling. |
1603 | polling. |
1376 | |
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 | |
1377 | =head3 Watcher-Specific Functions and Data Members |
1638 | =head3 Watcher-Specific Functions and Data Members |
1378 | |
1639 | |
1379 | =over 4 |
1640 | =over 4 |
1380 | |
1641 | |
1381 | =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) |
… | |
… | |
1390 | |
1651 | |
1391 | 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, |
1392 | 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 |
1393 | last change was detected). |
1654 | last change was detected). |
1394 | |
1655 | |
1395 | =item ev_stat_stat (ev_stat *) |
1656 | =item ev_stat_stat (loop, ev_stat *) |
1396 | |
1657 | |
1397 | 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 |
1398 | 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 |
1399 | detecting this change (while introducing a race condition). Can also be |
1660 | detecting this change (while introducing a race condition). Can also be |
1400 | useful simply to find out the new values. |
1661 | useful simply to find out the new values. |
… | |
… | |
1418 | =item const char *path [read-only] |
1679 | =item const char *path [read-only] |
1419 | |
1680 | |
1420 | The filesystem path that is being watched. |
1681 | The filesystem path that is being watched. |
1421 | |
1682 | |
1422 | =back |
1683 | =back |
|
|
1684 | |
|
|
1685 | =head3 Examples |
1423 | |
1686 | |
1424 | Example: Watch C</etc/passwd> for attribute changes. |
1687 | Example: Watch C</etc/passwd> for attribute changes. |
1425 | |
1688 | |
1426 | static void |
1689 | static void |
1427 | passwd_cb (struct ev_loop *loop, ev_stat *w, int revents) |
1690 | passwd_cb (struct ev_loop *loop, ev_stat *w, int revents) |
… | |
… | |
1440 | } |
1703 | } |
1441 | |
1704 | |
1442 | ... |
1705 | ... |
1443 | ev_stat passwd; |
1706 | ev_stat passwd; |
1444 | |
1707 | |
1445 | ev_stat_init (&passwd, passwd_cb, "/etc/passwd"); |
1708 | ev_stat_init (&passwd, passwd_cb, "/etc/passwd", 0.); |
1446 | 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); |
1447 | |
1738 | |
1448 | |
1739 | |
1449 | =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... |
1450 | |
1741 | |
1451 | 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 |
… | |
… | |
1477 | 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, |
1478 | believe me. |
1769 | believe me. |
1479 | |
1770 | |
1480 | =back |
1771 | =back |
1481 | |
1772 | |
|
|
1773 | =head3 Examples |
|
|
1774 | |
1482 | 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 |
1483 | callback, free it. Also, use no error checking, as usual. |
1776 | callback, free it. Also, use no error checking, as usual. |
1484 | |
1777 | |
1485 | static void |
1778 | static void |
1486 | 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) |
1487 | { |
1780 | { |
1488 | free (w); |
1781 | free (w); |
1489 | // now do something you wanted to do when the program has |
1782 | // now do something you wanted to do when the program has |
1490 | // no longer asnything immediate to do. |
1783 | // no longer anything immediate to do. |
1491 | } |
1784 | } |
1492 | |
1785 | |
1493 | struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle)); |
1786 | struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle)); |
1494 | ev_idle_init (idle_watcher, idle_cb); |
1787 | ev_idle_init (idle_watcher, idle_cb); |
1495 | ev_idle_start (loop, idle_cb); |
1788 | ev_idle_start (loop, idle_cb); |
… | |
… | |
1537 | |
1830 | |
1538 | 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>) |
1539 | 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 |
1540 | 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, |
1541 | too) should not activate ("feed") events into libev. While libev fully |
1834 | too) should not activate ("feed") events into libev. While libev fully |
1542 | 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 |
1543 | 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 |
1544 | 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 |
1545 | 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 |
1546 | others). |
1839 | coexist peacefully with others). |
1547 | |
1840 | |
1548 | =head3 Watcher-Specific Functions and Data Members |
1841 | =head3 Watcher-Specific Functions and Data Members |
1549 | |
1842 | |
1550 | =over 4 |
1843 | =over 4 |
1551 | |
1844 | |
… | |
… | |
1556 | Initialises and configures the prepare or check watcher - they have no |
1849 | Initialises and configures the prepare or check watcher - they have no |
1557 | 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> |
1558 | macros, but using them is utterly, utterly and completely pointless. |
1851 | macros, but using them is utterly, utterly and completely pointless. |
1559 | |
1852 | |
1560 | =back |
1853 | =back |
|
|
1854 | |
|
|
1855 | =head3 Examples |
1561 | |
1856 | |
1562 | 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 |
1563 | 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 |
1564 | (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 |
1565 | 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 | portable one. |
2029 | portable one. |
1735 | |
2030 | |
1736 | 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 |
1737 | 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 |
1738 | 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 |
1739 | 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). |
1740 | |
2069 | |
1741 | struct ev_loop *loop_hi = ev_default_init (0); |
2070 | struct ev_loop *loop_hi = ev_default_init (0); |
1742 | struct ev_loop *loop_lo = 0; |
2071 | struct ev_loop *loop_lo = 0; |
1743 | struct ev_embed embed; |
2072 | struct ev_embed embed; |
1744 | |
2073 | |
… | |
… | |
1755 | ev_embed_start (loop_hi, &embed); |
2084 | ev_embed_start (loop_hi, &embed); |
1756 | } |
2085 | } |
1757 | else |
2086 | else |
1758 | loop_lo = loop_hi; |
2087 | loop_lo = loop_hi; |
1759 | |
2088 | |
1760 | =head3 Watcher-Specific Functions and Data Members |
2089 | Example: Check if kqueue is available but not recommended and create |
|
|
2090 | a kqueue backend for use with sockets (which usually work with any |
|
|
2091 | kqueue implementation). Store the kqueue/socket-only event loop in |
|
|
2092 | C<loop_socket>. (One might optionally use C<EVFLAG_NOENV>, too). |
1761 | |
2093 | |
1762 | =over 4 |
2094 | struct ev_loop *loop = ev_default_init (0); |
|
|
2095 | struct ev_loop *loop_socket = 0; |
|
|
2096 | struct ev_embed embed; |
|
|
2097 | |
|
|
2098 | if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE) |
|
|
2099 | if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE)) |
|
|
2100 | { |
|
|
2101 | ev_embed_init (&embed, 0, loop_socket); |
|
|
2102 | ev_embed_start (loop, &embed); |
|
|
2103 | } |
1763 | |
2104 | |
1764 | =item ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop) |
2105 | if (!loop_socket) |
|
|
2106 | loop_socket = loop; |
1765 | |
2107 | |
1766 | =item ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop) |
2108 | // now use loop_socket for all sockets, and loop for everything else |
1767 | |
|
|
1768 | Configures the watcher to embed the given loop, which must be |
|
|
1769 | embeddable. If the callback is C<0>, then C<ev_embed_sweep> will be |
|
|
1770 | invoked automatically, otherwise it is the responsibility of the callback |
|
|
1771 | to invoke it (it will continue to be called until the sweep has been done, |
|
|
1772 | if you do not want thta, you need to temporarily stop the embed watcher). |
|
|
1773 | |
|
|
1774 | =item ev_embed_sweep (loop, ev_embed *) |
|
|
1775 | |
|
|
1776 | Make a single, non-blocking sweep over the embedded loop. This works |
|
|
1777 | similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most |
|
|
1778 | apropriate way for embedded loops. |
|
|
1779 | |
|
|
1780 | =item struct ev_loop *loop [read-only] |
|
|
1781 | |
|
|
1782 | The embedded event loop. |
|
|
1783 | |
|
|
1784 | =back |
|
|
1785 | |
2109 | |
1786 | |
2110 | |
1787 | =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 |
1788 | |
2112 | |
1789 | 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 |
… | |
… | |
1805 | believe me. |
2129 | believe me. |
1806 | |
2130 | |
1807 | =back |
2131 | =back |
1808 | |
2132 | |
1809 | |
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 | |
1810 | =head1 OTHER FUNCTIONS |
2265 | =head1 OTHER FUNCTIONS |
1811 | |
2266 | |
1812 | There are some other functions of possible interest. Described. Here. Now. |
2267 | There are some other functions of possible interest. Described. Here. Now. |
1813 | |
2268 | |
1814 | =over 4 |
2269 | =over 4 |
… | |
… | |
2019 | |
2474 | |
2020 | =item w->stop () |
2475 | =item w->stop () |
2021 | |
2476 | |
2022 | Stops the watcher if it is active. Again, no C<loop> argument. |
2477 | Stops the watcher if it is active. Again, no C<loop> argument. |
2023 | |
2478 | |
2024 | =item w->again () C<ev::timer>, C<ev::periodic> only |
2479 | =item w->again () (C<ev::timer>, C<ev::periodic> only) |
2025 | |
2480 | |
2026 | For C<ev::timer> and C<ev::periodic>, this invokes the corresponding |
2481 | For C<ev::timer> and C<ev::periodic>, this invokes the corresponding |
2027 | C<ev_TYPE_again> function. |
2482 | C<ev_TYPE_again> function. |
2028 | |
2483 | |
2029 | =item w->sweep () C<ev::embed> only |
2484 | =item w->sweep () (C<ev::embed> only) |
2030 | |
2485 | |
2031 | Invokes C<ev_embed_sweep>. |
2486 | Invokes C<ev_embed_sweep>. |
2032 | |
2487 | |
2033 | =item w->update () C<ev::stat> only |
2488 | =item w->update () (C<ev::stat> only) |
2034 | |
2489 | |
2035 | Invokes C<ev_stat_stat>. |
2490 | Invokes C<ev_stat_stat>. |
2036 | |
2491 | |
2037 | =back |
2492 | =back |
2038 | |
2493 | |
… | |
… | |
2041 | 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 |
2042 | the constructor. |
2497 | the constructor. |
2043 | |
2498 | |
2044 | class myclass |
2499 | class myclass |
2045 | { |
2500 | { |
2046 | ev_io io; void io_cb (ev::io &w, int revents); |
2501 | ev::io io; void io_cb (ev::io &w, int revents); |
2047 | ev_idle idle void idle_cb (ev::idle &w, int revents); |
2502 | ev:idle idle void idle_cb (ev::idle &w, int revents); |
2048 | |
2503 | |
2049 | myclass (); |
2504 | myclass (int fd) |
2050 | } |
|
|
2051 | |
|
|
2052 | myclass::myclass (int fd) |
|
|
2053 | { |
2505 | { |
2054 | io .set <myclass, &myclass::io_cb > (this); |
2506 | io .set <myclass, &myclass::io_cb > (this); |
2055 | idle.set <myclass, &myclass::idle_cb> (this); |
2507 | idle.set <myclass, &myclass::idle_cb> (this); |
2056 | |
2508 | |
2057 | io.start (fd, ev::READ); |
2509 | io.start (fd, ev::READ); |
|
|
2510 | } |
2058 | } |
2511 | }; |
2059 | |
2512 | |
2060 | |
2513 | |
2061 | =head1 MACRO MAGIC |
2514 | =head1 MACRO MAGIC |
2062 | |
2515 | |
2063 | Libev can be compiled with a variety of options, the most fundemantal is |
2516 | Libev can be compiled with a variety of options, the most fundamantal |
2064 | C<EV_MULTIPLICITY>. This option determines whether (most) functions and |
2517 | of which is C<EV_MULTIPLICITY>. This option determines whether (most) |
2065 | callbacks have an initial C<struct ev_loop *> argument. |
2518 | functions and callbacks have an initial C<struct ev_loop *> argument. |
2066 | |
2519 | |
2067 | To make it easier to write programs that cope with either variant, the |
2520 | To make it easier to write programs that cope with either variant, the |
2068 | following macros are defined: |
2521 | following macros are defined: |
2069 | |
2522 | |
2070 | =over 4 |
2523 | =over 4 |
… | |
… | |
2124 | Libev can (and often is) directly embedded into host |
2577 | Libev can (and often is) directly embedded into host |
2125 | applications. Examples of applications that embed it include the Deliantra |
2578 | applications. Examples of applications that embed it include the Deliantra |
2126 | Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe) |
2579 | Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe) |
2127 | and rxvt-unicode. |
2580 | and rxvt-unicode. |
2128 | |
2581 | |
2129 | The goal is to enable you to just copy the neecssary files into your |
2582 | The goal is to enable you to just copy the necessary files into your |
2130 | source directory without having to change even a single line in them, so |
2583 | source directory without having to change even a single line in them, so |
2131 | you can easily upgrade by simply copying (or having a checked-out copy of |
2584 | you can easily upgrade by simply copying (or having a checked-out copy of |
2132 | libev somewhere in your source tree). |
2585 | libev somewhere in your source tree). |
2133 | |
2586 | |
2134 | =head2 FILESETS |
2587 | =head2 FILESETS |
… | |
… | |
2224 | |
2677 | |
2225 | If defined to be C<1>, libev will try to detect the availability of the |
2678 | If defined to be C<1>, libev will try to detect the availability of the |
2226 | monotonic clock option at both compiletime and runtime. Otherwise no use |
2679 | monotonic clock option at both compiletime and runtime. Otherwise no use |
2227 | of the monotonic clock option will be attempted. If you enable this, you |
2680 | of the monotonic clock option will be attempted. If you enable this, you |
2228 | usually have to link against librt or something similar. Enabling it when |
2681 | usually have to link against librt or something similar. Enabling it when |
2229 | the functionality isn't available is safe, though, althoguh you have |
2682 | the functionality isn't available is safe, though, although you have |
2230 | to make sure you link against any libraries where the C<clock_gettime> |
2683 | to make sure you link against any libraries where the C<clock_gettime> |
2231 | function is hiding in (often F<-lrt>). |
2684 | function is hiding in (often F<-lrt>). |
2232 | |
2685 | |
2233 | =item EV_USE_REALTIME |
2686 | =item EV_USE_REALTIME |
2234 | |
2687 | |
2235 | If defined to be C<1>, libev will try to detect the availability of the |
2688 | If defined to be C<1>, libev will try to detect the availability of the |
2236 | realtime clock option at compiletime (and assume its availability at |
2689 | realtime clock option at compiletime (and assume its availability at |
2237 | runtime if successful). Otherwise no use of the realtime clock option will |
2690 | runtime if successful). Otherwise no use of the realtime clock option will |
2238 | be attempted. This effectively replaces C<gettimeofday> by C<clock_get |
2691 | be attempted. This effectively replaces C<gettimeofday> by C<clock_get |
2239 | (CLOCK_REALTIME, ...)> and will not normally affect correctness. See tzhe note about libraries |
2692 | (CLOCK_REALTIME, ...)> and will not normally affect correctness. See the |
2240 | in the description of C<EV_USE_MONOTONIC>, though. |
2693 | note about libraries in the description of C<EV_USE_MONOTONIC>, though. |
|
|
2694 | |
|
|
2695 | =item EV_USE_NANOSLEEP |
|
|
2696 | |
|
|
2697 | If defined to be C<1>, libev will assume that C<nanosleep ()> is available |
|
|
2698 | and will use it for delays. Otherwise it will use C<select ()>. |
2241 | |
2699 | |
2242 | =item EV_USE_SELECT |
2700 | =item EV_USE_SELECT |
2243 | |
2701 | |
2244 | If undefined or defined to be C<1>, libev will compile in support for the |
2702 | If undefined or defined to be C<1>, libev will compile in support for the |
2245 | C<select>(2) backend. No attempt at autodetection will be done: if no |
2703 | C<select>(2) backend. No attempt at autodetection will be done: if no |
… | |
… | |
2263 | wants osf handles on win32 (this is the case when the select to |
2721 | wants osf handles on win32 (this is the case when the select to |
2264 | be used is the winsock select). This means that it will call |
2722 | be used is the winsock select). This means that it will call |
2265 | C<_get_osfhandle> on the fd to convert it to an OS handle. Otherwise, |
2723 | C<_get_osfhandle> on the fd to convert it to an OS handle. Otherwise, |
2266 | it is assumed that all these functions actually work on fds, even |
2724 | it is assumed that all these functions actually work on fds, even |
2267 | on win32. Should not be defined on non-win32 platforms. |
2725 | on win32. Should not be defined on non-win32 platforms. |
|
|
2726 | |
|
|
2727 | =item EV_FD_TO_WIN32_HANDLE |
|
|
2728 | |
|
|
2729 | If C<EV_SELECT_IS_WINSOCKET> is enabled, then libev needs a way to map |
|
|
2730 | file descriptors to socket handles. When not defining this symbol (the |
|
|
2731 | default), then libev will call C<_get_osfhandle>, which is usually |
|
|
2732 | correct. In some cases, programs use their own file descriptor management, |
|
|
2733 | in which case they can provide this function to map fds to socket handles. |
2268 | |
2734 | |
2269 | =item EV_USE_POLL |
2735 | =item EV_USE_POLL |
2270 | |
2736 | |
2271 | If defined to be C<1>, libev will compile in support for the C<poll>(2) |
2737 | If defined to be C<1>, libev will compile in support for the C<poll>(2) |
2272 | backend. Otherwise it will be enabled on non-win32 platforms. It |
2738 | backend. Otherwise it will be enabled on non-win32 platforms. It |
… | |
… | |
2306 | |
2772 | |
2307 | If defined to be C<1>, libev will compile in support for the Linux inotify |
2773 | If defined to be C<1>, libev will compile in support for the Linux inotify |
2308 | interface to speed up C<ev_stat> watchers. Its actual availability will |
2774 | interface to speed up C<ev_stat> watchers. Its actual availability will |
2309 | be detected at runtime. |
2775 | be detected at runtime. |
2310 | |
2776 | |
|
|
2777 | =item EV_ATOMIC_T |
|
|
2778 | |
|
|
2779 | Libev requires an integer type (suitable for storing C<0> or C<1>) whose |
|
|
2780 | access is atomic with respect to other threads or signal contexts. No such |
|
|
2781 | type is easily found in the C language, so you can provide your own type |
|
|
2782 | that you know is safe for your purposes. It is used both for signal handler "locking" |
|
|
2783 | as well as for signal and thread safety in C<ev_async> watchers. |
|
|
2784 | |
|
|
2785 | In the absense of this define, libev will use C<sig_atomic_t volatile> |
|
|
2786 | (from F<signal.h>), which is usually good enough on most platforms. |
|
|
2787 | |
2311 | =item EV_H |
2788 | =item EV_H |
2312 | |
2789 | |
2313 | The name of the F<ev.h> header file used to include it. The default if |
2790 | The name of the F<ev.h> header file used to include it. The default if |
2314 | undefined is C<< <ev.h> >> in F<event.h> and C<"ev.h"> in F<ev.c>. This |
2791 | undefined is C<"ev.h"> in F<event.h>, F<ev.c> and F<ev++.h>. This can be |
2315 | can be used to virtually rename the F<ev.h> header file in case of conflicts. |
2792 | used to virtually rename the F<ev.h> header file in case of conflicts. |
2316 | |
2793 | |
2317 | =item EV_CONFIG_H |
2794 | =item EV_CONFIG_H |
2318 | |
2795 | |
2319 | If C<EV_STANDALONE> isn't C<1>, this variable can be used to override |
2796 | If C<EV_STANDALONE> isn't C<1>, this variable can be used to override |
2320 | F<ev.c>'s idea of where to find the F<config.h> file, similarly to |
2797 | F<ev.c>'s idea of where to find the F<config.h> file, similarly to |
2321 | C<EV_H>, above. |
2798 | C<EV_H>, above. |
2322 | |
2799 | |
2323 | =item EV_EVENT_H |
2800 | =item EV_EVENT_H |
2324 | |
2801 | |
2325 | Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea |
2802 | Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea |
2326 | of how the F<event.h> header can be found. |
2803 | of how the F<event.h> header can be found, the default is C<"event.h">. |
2327 | |
2804 | |
2328 | =item EV_PROTOTYPES |
2805 | =item EV_PROTOTYPES |
2329 | |
2806 | |
2330 | If defined to be C<0>, then F<ev.h> will not define any function |
2807 | If defined to be C<0>, then F<ev.h> will not define any function |
2331 | prototypes, but still define all the structs and other symbols. This is |
2808 | prototypes, but still define all the structs and other symbols. This is |
… | |
… | |
2382 | =item EV_FORK_ENABLE |
2859 | =item EV_FORK_ENABLE |
2383 | |
2860 | |
2384 | If undefined or defined to be C<1>, then fork watchers are supported. If |
2861 | If undefined or defined to be C<1>, then fork watchers are supported. If |
2385 | defined to be C<0>, then they are not. |
2862 | defined to be C<0>, then they are not. |
2386 | |
2863 | |
|
|
2864 | =item EV_ASYNC_ENABLE |
|
|
2865 | |
|
|
2866 | If undefined or defined to be C<1>, then async watchers are supported. If |
|
|
2867 | defined to be C<0>, then they are not. |
|
|
2868 | |
2387 | =item EV_MINIMAL |
2869 | =item EV_MINIMAL |
2388 | |
2870 | |
2389 | If you need to shave off some kilobytes of code at the expense of some |
2871 | If you need to shave off some kilobytes of code at the expense of some |
2390 | speed, define this symbol to C<1>. Currently only used for gcc to override |
2872 | speed, define this symbol to C<1>. Currently only used for gcc to override |
2391 | some inlining decisions, saves roughly 30% codesize of amd64. |
2873 | some inlining decisions, saves roughly 30% codesize of amd64. |
… | |
… | |
2397 | than enough. If you need to manage thousands of children you might want to |
2879 | than enough. If you need to manage thousands of children you might want to |
2398 | increase this value (I<must> be a power of two). |
2880 | increase this value (I<must> be a power of two). |
2399 | |
2881 | |
2400 | =item EV_INOTIFY_HASHSIZE |
2882 | =item EV_INOTIFY_HASHSIZE |
2401 | |
2883 | |
2402 | C<ev_staz> watchers use a small hash table to distribute workload by |
2884 | C<ev_stat> watchers use a small hash table to distribute workload by |
2403 | inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>), |
2885 | inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>), |
2404 | usually more than enough. If you need to manage thousands of C<ev_stat> |
2886 | usually more than enough. If you need to manage thousands of C<ev_stat> |
2405 | watchers you might want to increase this value (I<must> be a power of |
2887 | watchers you might want to increase this value (I<must> be a power of |
2406 | two). |
2888 | two). |
2407 | |
2889 | |
… | |
… | |
2424 | |
2906 | |
2425 | =item ev_set_cb (ev, cb) |
2907 | =item ev_set_cb (ev, cb) |
2426 | |
2908 | |
2427 | Can be used to change the callback member declaration in each watcher, |
2909 | Can be used to change the callback member declaration in each watcher, |
2428 | and the way callbacks are invoked and set. Must expand to a struct member |
2910 | and the way callbacks are invoked and set. Must expand to a struct member |
2429 | definition and a statement, respectively. See the F<ev.v> header file for |
2911 | definition and a statement, respectively. See the F<ev.h> header file for |
2430 | their default definitions. One possible use for overriding these is to |
2912 | their default definitions. One possible use for overriding these is to |
2431 | avoid the C<struct ev_loop *> as first argument in all cases, or to use |
2913 | avoid the C<struct ev_loop *> as first argument in all cases, or to use |
2432 | method calls instead of plain function calls in C++. |
2914 | method calls instead of plain function calls in C++. |
|
|
2915 | |
|
|
2916 | =head2 EXPORTED API SYMBOLS |
|
|
2917 | |
|
|
2918 | If you need to re-export the API (e.g. via a dll) and you need a list of |
|
|
2919 | exported symbols, you can use the provided F<Symbol.*> files which list |
|
|
2920 | all public symbols, one per line: |
|
|
2921 | |
|
|
2922 | Symbols.ev for libev proper |
|
|
2923 | Symbols.event for the libevent emulation |
|
|
2924 | |
|
|
2925 | This can also be used to rename all public symbols to avoid clashes with |
|
|
2926 | multiple versions of libev linked together (which is obviously bad in |
|
|
2927 | itself, but sometimes it is inconvinient to avoid this). |
|
|
2928 | |
|
|
2929 | A sed command like this will create wrapper C<#define>'s that you need to |
|
|
2930 | include before including F<ev.h>: |
|
|
2931 | |
|
|
2932 | <Symbols.ev sed -e "s/.*/#define & myprefix_&/" >wrap.h |
|
|
2933 | |
|
|
2934 | This would create a file F<wrap.h> which essentially looks like this: |
|
|
2935 | |
|
|
2936 | #define ev_backend myprefix_ev_backend |
|
|
2937 | #define ev_check_start myprefix_ev_check_start |
|
|
2938 | #define ev_check_stop myprefix_ev_check_stop |
|
|
2939 | ... |
2433 | |
2940 | |
2434 | =head2 EXAMPLES |
2941 | =head2 EXAMPLES |
2435 | |
2942 | |
2436 | For a real-world example of a program the includes libev |
2943 | For a real-world example of a program the includes libev |
2437 | verbatim, you can have a look at the EV perl module |
2944 | verbatim, you can have a look at the EV perl module |
… | |
… | |
2478 | |
2985 | |
2479 | =item Starting and stopping timer/periodic watchers: O(log skipped_other_timers) |
2986 | =item Starting and stopping timer/periodic watchers: O(log skipped_other_timers) |
2480 | |
2987 | |
2481 | This means that, when you have a watcher that triggers in one hour and |
2988 | This means that, when you have a watcher that triggers in one hour and |
2482 | there are 100 watchers that would trigger before that then inserting will |
2989 | there are 100 watchers that would trigger before that then inserting will |
2483 | have to skip those 100 watchers. |
2990 | have to skip roughly seven (C<ld 100>) of these watchers. |
2484 | |
2991 | |
2485 | =item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers) |
2992 | =item Changing timer/periodic watchers (by autorepeat or calling again): O(log skipped_other_timers) |
2486 | |
2993 | |
2487 | That means that for changing a timer costs less than removing/adding them |
2994 | That means that changing a timer costs less than removing/adding them |
2488 | as only the relative motion in the event queue has to be paid for. |
2995 | as only the relative motion in the event queue has to be paid for. |
2489 | |
2996 | |
2490 | =item Starting io/check/prepare/idle/signal/child watchers: O(1) |
2997 | =item Starting io/check/prepare/idle/signal/child/fork/async watchers: O(1) |
2491 | |
2998 | |
2492 | These just add the watcher into an array or at the head of a list. |
2999 | These just add the watcher into an array or at the head of a list. |
|
|
3000 | |
2493 | =item Stopping check/prepare/idle watchers: O(1) |
3001 | =item Stopping check/prepare/idle/fork/async watchers: O(1) |
2494 | |
3002 | |
2495 | =item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE)) |
3003 | =item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE)) |
2496 | |
3004 | |
2497 | These watchers are stored in lists then need to be walked to find the |
3005 | These watchers are stored in lists then need to be walked to find the |
2498 | correct watcher to remove. The lists are usually short (you don't usually |
3006 | correct watcher to remove. The lists are usually short (you don't usually |
2499 | have many watchers waiting for the same fd or signal). |
3007 | have many watchers waiting for the same fd or signal). |
2500 | |
3008 | |
2501 | =item Finding the next timer per loop iteration: O(1) |
3009 | =item Finding the next timer in each loop iteration: O(1) |
|
|
3010 | |
|
|
3011 | By virtue of using a binary heap, the next timer is always found at the |
|
|
3012 | beginning of the storage array. |
2502 | |
3013 | |
2503 | =item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd) |
3014 | =item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd) |
2504 | |
3015 | |
2505 | A change means an I/O watcher gets started or stopped, which requires |
3016 | A change means an I/O watcher gets started or stopped, which requires |
2506 | libev to recalculate its status (and possibly tell the kernel). |
3017 | libev to recalculate its status (and possibly tell the kernel, depending |
|
|
3018 | on backend and wether C<ev_io_set> was used). |
2507 | |
3019 | |
2508 | =item Activating one watcher: O(1) |
3020 | =item Activating one watcher (putting it into the pending state): O(1) |
2509 | |
3021 | |
2510 | =item Priority handling: O(number_of_priorities) |
3022 | =item Priority handling: O(number_of_priorities) |
2511 | |
3023 | |
2512 | Priorities are implemented by allocating some space for each |
3024 | Priorities are implemented by allocating some space for each |
2513 | priority. When doing priority-based operations, libev usually has to |
3025 | priority. When doing priority-based operations, libev usually has to |
2514 | linearly search all the priorities. |
3026 | linearly search all the priorities, but starting/stopping and activating |
|
|
3027 | watchers becomes O(1) w.r.t. priority handling. |
|
|
3028 | |
|
|
3029 | =item Sending an ev_async: O(1) |
|
|
3030 | |
|
|
3031 | =item Processing ev_async_send: O(number_of_async_watchers) |
|
|
3032 | |
|
|
3033 | =item Processing signals: O(max_signal_number) |
|
|
3034 | |
|
|
3035 | Sending involves a syscall I<iff> there were no other C<ev_async_send> |
|
|
3036 | calls in the current loop iteration. Checking for async and signal events |
|
|
3037 | involves iterating over all running async watchers or all signal numbers. |
2515 | |
3038 | |
2516 | =back |
3039 | =back |
2517 | |
3040 | |
2518 | |
3041 | |
|
|
3042 | =head1 Win32 platform limitations and workarounds |
|
|
3043 | |
|
|
3044 | Win32 doesn't support any of the standards (e.g. POSIX) that libev |
|
|
3045 | requires, and its I/O model is fundamentally incompatible with the POSIX |
|
|
3046 | model. Libev still offers limited functionality on this platform in |
|
|
3047 | the form of the C<EVBACKEND_SELECT> backend, and only supports socket |
|
|
3048 | descriptors. This only applies when using Win32 natively, not when using |
|
|
3049 | e.g. cygwin. |
|
|
3050 | |
|
|
3051 | There is no supported compilation method available on windows except |
|
|
3052 | embedding it into other applications. |
|
|
3053 | |
|
|
3054 | Due to the many, low, and arbitrary limits on the win32 platform and the |
|
|
3055 | abysmal performance of winsockets, using a large number of sockets is not |
|
|
3056 | recommended (and not reasonable). If your program needs to use more than |
|
|
3057 | a hundred or so sockets, then likely it needs to use a totally different |
|
|
3058 | implementation for windows, as libev offers the POSIX model, which cannot |
|
|
3059 | be implemented efficiently on windows (microsoft monopoly games). |
|
|
3060 | |
|
|
3061 | =over 4 |
|
|
3062 | |
|
|
3063 | =item The winsocket select function |
|
|
3064 | |
|
|
3065 | The winsocket C<select> function doesn't follow POSIX in that it requires |
|
|
3066 | socket I<handles> and not socket I<file descriptors>. This makes select |
|
|
3067 | very inefficient, and also requires a mapping from file descriptors |
|
|
3068 | to socket handles. See the discussion of the C<EV_SELECT_USE_FD_SET>, |
|
|
3069 | C<EV_SELECT_IS_WINSOCKET> and C<EV_FD_TO_WIN32_HANDLE> preprocessor |
|
|
3070 | symbols for more info. |
|
|
3071 | |
|
|
3072 | The configuration for a "naked" win32 using the microsoft runtime |
|
|
3073 | libraries and raw winsocket select is: |
|
|
3074 | |
|
|
3075 | #define EV_USE_SELECT 1 |
|
|
3076 | #define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */ |
|
|
3077 | |
|
|
3078 | Note that winsockets handling of fd sets is O(n), so you can easily get a |
|
|
3079 | complexity in the O(n²) range when using win32. |
|
|
3080 | |
|
|
3081 | =item Limited number of file descriptors |
|
|
3082 | |
|
|
3083 | Windows has numerous arbitrary (and low) limits on things. Early versions |
|
|
3084 | of winsocket's select only supported waiting for a max. of C<64> handles |
|
|
3085 | (probably owning to the fact that all windows kernels can only wait for |
|
|
3086 | C<64> things at the same time internally; microsoft recommends spawning a |
|
|
3087 | chain of threads and wait for 63 handles and the previous thread in each). |
|
|
3088 | |
|
|
3089 | Newer versions support more handles, but you need to define C<FD_SETSIZE> |
|
|
3090 | to some high number (e.g. C<2048>) before compiling the winsocket select |
|
|
3091 | call (which might be in libev or elsewhere, for example, perl does its own |
|
|
3092 | select emulation on windows). |
|
|
3093 | |
|
|
3094 | Another limit is the number of file descriptors in the microsoft runtime |
|
|
3095 | libraries, which by default is C<64> (there must be a hidden I<64> fetish |
|
|
3096 | or something like this inside microsoft). You can increase this by calling |
|
|
3097 | C<_setmaxstdio>, which can increase this limit to C<2048> (another |
|
|
3098 | arbitrary limit), but is broken in many versions of the microsoft runtime |
|
|
3099 | libraries. |
|
|
3100 | |
|
|
3101 | This might get you to about C<512> or C<2048> sockets (depending on |
|
|
3102 | windows version and/or the phase of the moon). To get more, you need to |
|
|
3103 | wrap all I/O functions and provide your own fd management, but the cost of |
|
|
3104 | calling select (O(n²)) will likely make this unworkable. |
|
|
3105 | |
|
|
3106 | =back |
|
|
3107 | |
|
|
3108 | |
2519 | =head1 AUTHOR |
3109 | =head1 AUTHOR |
2520 | |
3110 | |
2521 | Marc Lehmann <libev@schmorp.de>. |
3111 | Marc Lehmann <libev@schmorp.de>. |
2522 | |
3112 | |