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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 | #include <ev.h> |
11 | #include <ev.h> |
12 | |
12 | |
13 | ev_io stdin_watcher; |
13 | ev_io stdin_watcher; |
14 | ev_timer timeout_watcher; |
14 | ev_timer timeout_watcher; |
… | |
… | |
53 | The newest version of this document is also available as a html-formatted |
53 | The newest version of this document is also available as a html-formatted |
54 | web page you might find easier to navigate when reading it for the first |
54 | web page you might find easier to navigate when reading it for the first |
55 | time: L<http://cvs.schmorp.de/libev/ev.html>. |
55 | time: L<http://cvs.schmorp.de/libev/ev.html>. |
56 | |
56 | |
57 | Libev is an event loop: you register interest in certain events (such as a |
57 | 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 |
58 | file descriptor being readable or a timeout occurring), and it will manage |
59 | these event sources and provide your program with events. |
59 | these event sources and provide your program with events. |
60 | |
60 | |
61 | To do this, it must take more or less complete control over your process |
61 | 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 |
62 | (or thread) by executing the I<event loop> handler, and will then |
63 | communicate events via a callback mechanism. |
63 | communicate events via a callback mechanism. |
… | |
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65 | You register interest in certain events by registering so-called I<event |
65 | You register interest in certain events by registering so-called I<event |
66 | watchers>, which are relatively small C structures you initialise with the |
66 | 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 |
67 | details of the event, and then hand it over to libev by I<starting> the |
68 | watcher. |
68 | watcher. |
69 | |
69 | |
70 | =head1 FEATURES |
70 | =head2 FEATURES |
71 | |
71 | |
72 | Libev supports C<select>, C<poll>, the Linux-specific C<epoll>, the |
72 | Libev supports C<select>, C<poll>, the Linux-specific C<epoll>, the |
73 | BSD-specific C<kqueue> and the Solaris-specific event port mechanisms |
73 | BSD-specific C<kqueue> and the Solaris-specific event port mechanisms |
74 | for file descriptor events (C<ev_io>), the Linux C<inotify> interface |
74 | for file descriptor events (C<ev_io>), the Linux C<inotify> interface |
75 | (for C<ev_stat>), relative timers (C<ev_timer>), absolute timers |
75 | (for C<ev_stat>), relative timers (C<ev_timer>), absolute timers |
… | |
… | |
82 | |
82 | |
83 | It also is quite fast (see this |
83 | It also is quite fast (see this |
84 | L<benchmark|http://libev.schmorp.de/bench.html> comparing it to libevent |
84 | L<benchmark|http://libev.schmorp.de/bench.html> comparing it to libevent |
85 | for example). |
85 | for example). |
86 | |
86 | |
87 | =head1 CONVENTIONS |
87 | =head2 CONVENTIONS |
88 | |
88 | |
89 | Libev is very configurable. In this manual the default configuration will |
89 | Libev is very configurable. In this manual the default configuration will |
90 | be described, which supports multiple event loops. For more info about |
90 | be described, which supports multiple event loops. For more info about |
91 | various configuration options please have a look at B<EMBED> section in |
91 | various configuration options please have a look at B<EMBED> section in |
92 | this manual. If libev was configured without support for multiple event |
92 | this manual. If libev was configured without support for multiple event |
93 | loops, then all functions taking an initial argument of name C<loop> |
93 | loops, then all functions taking an initial argument of name C<loop> |
94 | (which is always of type C<struct ev_loop *>) will not have this argument. |
94 | (which is always of type C<struct ev_loop *>) will not have this argument. |
95 | |
95 | |
96 | =head1 TIME REPRESENTATION |
96 | =head2 TIME REPRESENTATION |
97 | |
97 | |
98 | Libev represents time as a single floating point number, representing the |
98 | Libev represents time as a single floating point number, representing the |
99 | (fractional) number of seconds since the (POSIX) epoch (somewhere near |
99 | (fractional) number of seconds since the (POSIX) epoch (somewhere near |
100 | the beginning of 1970, details are complicated, don't ask). This type is |
100 | 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 |
101 | 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 |
102 | to the C<double> type in C, and when you need to do any calculations on |
103 | it, you should treat it as such. |
103 | it, you should treat it as some floatingpoint value. Unlike the name |
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104 | component C<stamp> might indicate, it is also used for time differences |
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105 | throughout libev. |
104 | |
106 | |
105 | =head1 GLOBAL FUNCTIONS |
107 | =head1 GLOBAL FUNCTIONS |
106 | |
108 | |
107 | These functions can be called anytime, even before initialising the |
109 | These functions can be called anytime, even before initialising the |
108 | library in any way. |
110 | library in any way. |
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113 | |
115 | |
114 | Returns the current time as libev would use it. Please note that the |
116 | 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 |
117 | C<ev_now> function is usually faster and also often returns the timestamp |
116 | you actually want to know. |
118 | you actually want to know. |
117 | |
119 | |
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120 | =item ev_sleep (ev_tstamp interval) |
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121 | |
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122 | Sleep for the given interval: The current thread will be blocked until |
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123 | either it is interrupted or the given time interval has passed. Basically |
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124 | this is a subsecond-resolution C<sleep ()>. |
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125 | |
118 | =item int ev_version_major () |
126 | =item int ev_version_major () |
119 | |
127 | |
120 | =item int ev_version_minor () |
128 | =item int ev_version_minor () |
121 | |
129 | |
122 | You can find out the major and minor version numbers of the library |
130 | You can find out the major and minor ABI version numbers of the library |
123 | you linked against by calling the functions C<ev_version_major> and |
131 | you linked against by calling the functions C<ev_version_major> and |
124 | C<ev_version_minor>. If you want, you can compare against the global |
132 | C<ev_version_minor>. If you want, you can compare against the global |
125 | symbols C<EV_VERSION_MAJOR> and C<EV_VERSION_MINOR>, which specify the |
133 | symbols C<EV_VERSION_MAJOR> and C<EV_VERSION_MINOR>, which specify the |
126 | version of the library your program was compiled against. |
134 | version of the library your program was compiled against. |
127 | |
135 | |
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136 | These version numbers refer to the ABI version of the library, not the |
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137 | release version. |
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138 | |
128 | Usually, it's a good idea to terminate if the major versions mismatch, |
139 | Usually, it's a good idea to terminate if the major versions mismatch, |
129 | as this indicates an incompatible change. Minor versions are usually |
140 | as this indicates an incompatible change. Minor versions are usually |
130 | compatible to older versions, so a larger minor version alone is usually |
141 | compatible to older versions, so a larger minor version alone is usually |
131 | not a problem. |
142 | not a problem. |
132 | |
143 | |
133 | Example: Make sure we haven't accidentally been linked against the wrong |
144 | Example: Make sure we haven't accidentally been linked against the wrong |
134 | version. |
145 | version. |
… | |
… | |
295 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
306 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
296 | |
307 | |
297 | This is your standard select(2) backend. Not I<completely> standard, as |
308 | This is your standard select(2) backend. Not I<completely> standard, as |
298 | libev tries to roll its own fd_set with no limits on the number of fds, |
309 | libev tries to roll its own fd_set with no limits on the number of fds, |
299 | but if that fails, expect a fairly low limit on the number of fds when |
310 | but if that fails, expect a fairly low limit on the number of fds when |
300 | using this backend. It doesn't scale too well (O(highest_fd)), but its usually |
311 | using this backend. It doesn't scale too well (O(highest_fd)), but its |
301 | the fastest backend for a low number of fds. |
312 | usually the fastest backend for a low number of (low-numbered :) fds. |
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313 | |
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314 | To get good performance out of this backend you need a high amount of |
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315 | parallelity (most of the file descriptors should be busy). If you are |
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316 | writing a server, you should C<accept ()> in a loop to accept as many |
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317 | connections as possible during one iteration. You might also want to have |
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318 | a look at C<ev_set_io_collect_interval ()> to increase the amount of |
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319 | readyness notifications you get per iteration. |
302 | |
320 | |
303 | =item C<EVBACKEND_POLL> (value 2, poll backend, available everywhere except on windows) |
321 | =item C<EVBACKEND_POLL> (value 2, poll backend, available everywhere except on windows) |
304 | |
322 | |
305 | And this is your standard poll(2) backend. It's more complicated than |
323 | And this is your standard poll(2) backend. It's more complicated |
306 | select, but handles sparse fds better and has no artificial limit on the |
324 | than select, but handles sparse fds better and has no artificial |
307 | number of fds you can use (except it will slow down considerably with a |
325 | limit on the number of fds you can use (except it will slow down |
308 | lot of inactive fds). It scales similarly to select, i.e. O(total_fds). |
326 | considerably with a lot of inactive fds). It scales similarly to select, |
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327 | i.e. O(total_fds). See the entry for C<EVBACKEND_SELECT>, above, for |
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328 | performance tips. |
309 | |
329 | |
310 | =item C<EVBACKEND_EPOLL> (value 4, Linux) |
330 | =item C<EVBACKEND_EPOLL> (value 4, Linux) |
311 | |
331 | |
312 | For few fds, this backend is a bit little slower than poll and select, |
332 | For few fds, this backend is a bit little slower than poll and select, |
313 | but it scales phenomenally better. While poll and select usually scale like |
333 | but it scales phenomenally better. While poll and select usually scale |
314 | O(total_fds) where n is the total number of fds (or the highest fd), epoll scales |
334 | like O(total_fds) where n is the total number of fds (or the highest fd), |
315 | either O(1) or O(active_fds). |
335 | epoll scales either O(1) or O(active_fds). The epoll design has a number |
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336 | of shortcomings, such as silently dropping events in some hard-to-detect |
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337 | cases and rewiring a syscall per fd change, no fork support and bad |
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338 | support for dup. |
316 | |
339 | |
317 | While stopping and starting an I/O watcher in the same iteration will |
340 | While stopping, setting and starting an I/O watcher in the same iteration |
318 | result in some caching, there is still a syscall per such incident |
341 | will result in some caching, there is still a syscall per such incident |
319 | (because the fd could point to a different file description now), so its |
342 | (because the fd could point to a different file description now), so its |
320 | best to avoid that. Also, dup()ed file descriptors might not work very |
343 | best to avoid that. Also, C<dup ()>'ed file descriptors might not work |
321 | well if you register events for both fds. |
344 | very well if you register events for both fds. |
322 | |
345 | |
323 | Please note that epoll sometimes generates spurious notifications, so you |
346 | Please note that epoll sometimes generates spurious notifications, so you |
324 | need to use non-blocking I/O or other means to avoid blocking when no data |
347 | need to use non-blocking I/O or other means to avoid blocking when no data |
325 | (or space) is available. |
348 | (or space) is available. |
326 | |
349 | |
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350 | Best performance from this backend is achieved by not unregistering all |
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351 | watchers for a file descriptor until it has been closed, if possible, i.e. |
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352 | keep at least one watcher active per fd at all times. |
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353 | |
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354 | While nominally embeddeble in other event loops, this feature is broken in |
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355 | all kernel versions tested so far. |
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356 | |
327 | =item C<EVBACKEND_KQUEUE> (value 8, most BSD clones) |
357 | =item C<EVBACKEND_KQUEUE> (value 8, most BSD clones) |
328 | |
358 | |
329 | Kqueue deserves special mention, as at the time of this writing, it |
359 | Kqueue deserves special mention, as at the time of this writing, it |
330 | was broken on all BSDs except NetBSD (usually it doesn't work with |
360 | was broken on all BSDs except NetBSD (usually it doesn't work reliably |
331 | anything but sockets and pipes, except on Darwin, where of course its |
361 | with anything but sockets and pipes, except on Darwin, where of course |
332 | completely useless). For this reason its not being "autodetected" |
362 | it's completely useless). For this reason it's not being "autodetected" |
333 | unless you explicitly specify it explicitly in the flags (i.e. using |
363 | unless you explicitly specify it explicitly in the flags (i.e. using |
334 | C<EVBACKEND_KQUEUE>). |
364 | C<EVBACKEND_KQUEUE>) or libev was compiled on a known-to-be-good (-enough) |
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365 | system like NetBSD. |
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366 | |
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367 | You still can embed kqueue into a normal poll or select backend and use it |
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368 | only for sockets (after having made sure that sockets work with kqueue on |
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369 | the target platform). See C<ev_embed> watchers for more info. |
335 | |
370 | |
336 | It scales in the same way as the epoll backend, but the interface to the |
371 | It scales in the same way as the epoll backend, but the interface to the |
337 | kernel is more efficient (which says nothing about its actual speed, of |
372 | kernel is more efficient (which says nothing about its actual speed, of |
338 | course). While starting and stopping an I/O watcher does not cause an |
373 | course). While stopping, setting and starting an I/O watcher does never |
339 | extra syscall as with epoll, it still adds up to four event changes per |
374 | cause an extra syscall as with C<EVBACKEND_EPOLL>, it still adds up to |
340 | incident, so its best to avoid that. |
375 | two event changes per incident, support for C<fork ()> is very bad and it |
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376 | drops fds silently in similarly hard-to-detect cases. |
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377 | |
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378 | This backend usually performs well under most conditions. |
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379 | |
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380 | While nominally embeddable in other event loops, this doesn't work |
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381 | everywhere, so you might need to test for this. And since it is broken |
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382 | almost everywhere, you should only use it when you have a lot of sockets |
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383 | (for which it usually works), by embedding it into another event loop |
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384 | (e.g. C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>) and using it only for |
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385 | sockets. |
341 | |
386 | |
342 | =item C<EVBACKEND_DEVPOLL> (value 16, Solaris 8) |
387 | =item C<EVBACKEND_DEVPOLL> (value 16, Solaris 8) |
343 | |
388 | |
344 | This is not implemented yet (and might never be). |
389 | This is not implemented yet (and might never be, unless you send me an |
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390 | implementation). According to reports, C</dev/poll> only supports sockets |
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391 | and is not embeddable, which would limit the usefulness of this backend |
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392 | immensely. |
345 | |
393 | |
346 | =item C<EVBACKEND_PORT> (value 32, Solaris 10) |
394 | =item C<EVBACKEND_PORT> (value 32, Solaris 10) |
347 | |
395 | |
348 | This uses the Solaris 10 port mechanism. As with everything on Solaris, |
396 | This uses the Solaris 10 event port mechanism. As with everything on Solaris, |
349 | it's really slow, but it still scales very well (O(active_fds)). |
397 | it's really slow, but it still scales very well (O(active_fds)). |
350 | |
398 | |
351 | Please note that solaris ports can result in a lot of spurious |
399 | Please note that solaris event ports can deliver a lot of spurious |
352 | notifications, so you need to use non-blocking I/O or other means to avoid |
400 | notifications, so you need to use non-blocking I/O or other means to avoid |
353 | blocking when no data (or space) is available. |
401 | blocking when no data (or space) is available. |
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402 | |
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403 | While this backend scales well, it requires one system call per active |
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404 | file descriptor per loop iteration. For small and medium numbers of file |
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405 | descriptors a "slow" C<EVBACKEND_SELECT> or C<EVBACKEND_POLL> backend |
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406 | might perform better. |
354 | |
407 | |
355 | =item C<EVBACKEND_ALL> |
408 | =item C<EVBACKEND_ALL> |
356 | |
409 | |
357 | Try all backends (even potentially broken ones that wouldn't be tried |
410 | Try all backends (even potentially broken ones that wouldn't be tried |
358 | with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as |
411 | with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as |
359 | C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>. |
412 | C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>. |
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413 | |
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414 | It is definitely not recommended to use this flag. |
360 | |
415 | |
361 | =back |
416 | =back |
362 | |
417 | |
363 | If one or more of these are ored into the flags value, then only these |
418 | If one or more of these are ored into the flags value, then only these |
364 | backends will be tried (in the reverse order as given here). If none are |
419 | backends will be tried (in the reverse order as given here). If none are |
… | |
… | |
399 | Destroys the default loop again (frees all memory and kernel state |
454 | Destroys the default loop again (frees all memory and kernel state |
400 | etc.). None of the active event watchers will be stopped in the normal |
455 | etc.). None of the active event watchers will be stopped in the normal |
401 | sense, so e.g. C<ev_is_active> might still return true. It is your |
456 | sense, so e.g. C<ev_is_active> might still return true. It is your |
402 | responsibility to either stop all watchers cleanly yoursef I<before> |
457 | responsibility to either stop all watchers cleanly yoursef I<before> |
403 | calling this function, or cope with the fact afterwards (which is usually |
458 | calling this function, or cope with the fact afterwards (which is usually |
404 | the easiest thing, youc na just ignore the watchers and/or C<free ()> them |
459 | the easiest thing, you can just ignore the watchers and/or C<free ()> them |
405 | for example). |
460 | for example). |
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461 | |
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462 | Note that certain global state, such as signal state, will not be freed by |
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463 | this function, and related watchers (such as signal and child watchers) |
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464 | would need to be stopped manually. |
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465 | |
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466 | In general it is not advisable to call this function except in the |
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467 | rare occasion where you really need to free e.g. the signal handling |
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468 | pipe fds. If you need dynamically allocated loops it is better to use |
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469 | C<ev_loop_new> and C<ev_loop_destroy>). |
406 | |
470 | |
407 | =item ev_loop_destroy (loop) |
471 | =item ev_loop_destroy (loop) |
408 | |
472 | |
409 | Like C<ev_default_destroy>, but destroys an event loop created by an |
473 | Like C<ev_default_destroy>, but destroys an event loop created by an |
410 | earlier call to C<ev_loop_new>. |
474 | earlier call to C<ev_loop_new>. |
… | |
… | |
455 | |
519 | |
456 | Returns the current "event loop time", which is the time the event loop |
520 | Returns the current "event loop time", which is the time the event loop |
457 | received events and started processing them. This timestamp does not |
521 | received events and started processing them. This timestamp does not |
458 | change as long as callbacks are being processed, and this is also the base |
522 | change as long as callbacks are being processed, and this is also the base |
459 | time used for relative timers. You can treat it as the timestamp of the |
523 | time used for relative timers. You can treat it as the timestamp of the |
460 | event occuring (or more correctly, libev finding out about it). |
524 | event occurring (or more correctly, libev finding out about it). |
461 | |
525 | |
462 | =item ev_loop (loop, int flags) |
526 | =item ev_loop (loop, int flags) |
463 | |
527 | |
464 | Finally, this is it, the event handler. This function usually is called |
528 | Finally, this is it, the event handler. This function usually is called |
465 | after you initialised all your watchers and you want to start handling |
529 | after you initialised all your watchers and you want to start handling |
… | |
… | |
486 | libev watchers. However, a pair of C<ev_prepare>/C<ev_check> watchers is |
550 | libev watchers. However, a pair of C<ev_prepare>/C<ev_check> watchers is |
487 | usually a better approach for this kind of thing. |
551 | usually a better approach for this kind of thing. |
488 | |
552 | |
489 | Here are the gory details of what C<ev_loop> does: |
553 | Here are the gory details of what C<ev_loop> does: |
490 | |
554 | |
|
|
555 | - Before the first iteration, call any pending watchers. |
491 | * If there are no active watchers (reference count is zero), return. |
556 | * If there are no active watchers (reference count is zero), return. |
492 | - Queue prepare watchers and then call all outstanding watchers. |
557 | - Queue all prepare watchers and then call all outstanding watchers. |
493 | - If we have been forked, recreate the kernel state. |
558 | - If we have been forked, recreate the kernel state. |
494 | - Update the kernel state with all outstanding changes. |
559 | - Update the kernel state with all outstanding changes. |
495 | - Update the "event loop time". |
560 | - Update the "event loop time". |
496 | - Calculate for how long to block. |
561 | - Calculate for how long to block. |
497 | - Block the process, waiting for any events. |
562 | - Block the process, waiting for any events. |
… | |
… | |
548 | Example: For some weird reason, unregister the above signal handler again. |
613 | Example: For some weird reason, unregister the above signal handler again. |
549 | |
614 | |
550 | ev_ref (loop); |
615 | ev_ref (loop); |
551 | ev_signal_stop (loop, &exitsig); |
616 | ev_signal_stop (loop, &exitsig); |
552 | |
617 | |
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618 | =item ev_set_io_collect_interval (loop, ev_tstamp interval) |
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619 | |
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620 | =item ev_set_timeout_collect_interval (loop, ev_tstamp interval) |
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621 | |
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622 | These advanced functions influence the time that libev will spend waiting |
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623 | for events. Both are by default C<0>, meaning that libev will try to |
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624 | invoke timer/periodic callbacks and I/O callbacks with minimum latency. |
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625 | |
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626 | Setting these to a higher value (the C<interval> I<must> be >= C<0>) |
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627 | allows libev to delay invocation of I/O and timer/periodic callbacks to |
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628 | increase efficiency of loop iterations. |
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629 | |
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630 | The background is that sometimes your program runs just fast enough to |
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631 | handle one (or very few) event(s) per loop iteration. While this makes |
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632 | the program responsive, it also wastes a lot of CPU time to poll for new |
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633 | events, especially with backends like C<select ()> which have a high |
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634 | overhead for the actual polling but can deliver many events at once. |
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635 | |
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636 | By setting a higher I<io collect interval> you allow libev to spend more |
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637 | time collecting I/O events, so you can handle more events per iteration, |
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638 | at the cost of increasing latency. Timeouts (both C<ev_periodic> and |
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639 | C<ev_timer>) will be not affected. Setting this to a non-null value will |
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640 | introduce an additional C<ev_sleep ()> call into most loop iterations. |
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641 | |
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642 | Likewise, by setting a higher I<timeout collect interval> you allow libev |
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643 | to spend more time collecting timeouts, at the expense of increased |
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644 | latency (the watcher callback will be called later). C<ev_io> watchers |
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645 | will not be affected. Setting this to a non-null value will not introduce |
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646 | any overhead in libev. |
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647 | |
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648 | Many (busy) programs can usually benefit by setting the io collect |
|
|
649 | interval to a value near C<0.1> or so, which is often enough for |
|
|
650 | interactive servers (of course not for games), likewise for timeouts. It |
|
|
651 | usually doesn't make much sense to set it to a lower value than C<0.01>, |
|
|
652 | as this approsaches the timing granularity of most systems. |
|
|
653 | |
553 | =back |
654 | =back |
554 | |
655 | |
555 | |
656 | |
556 | =head1 ANATOMY OF A WATCHER |
657 | =head1 ANATOMY OF A WATCHER |
557 | |
658 | |
… | |
… | |
907 | play around with an Xlib connection), then you have to seperately re-test |
1008 | play around with an Xlib connection), then you have to seperately re-test |
908 | whether a file descriptor is really ready with a known-to-be good interface |
1009 | whether a file descriptor is really ready with a known-to-be good interface |
909 | such as poll (fortunately in our Xlib example, Xlib already does this on |
1010 | such as poll (fortunately in our Xlib example, Xlib already does this on |
910 | its own, so its quite safe to use). |
1011 | its own, so its quite safe to use). |
911 | |
1012 | |
|
|
1013 | =head3 The special problem of disappearing file descriptors |
|
|
1014 | |
|
|
1015 | Some backends (e.g. kqueue, epoll) need to be told about closing a file |
|
|
1016 | descriptor (either by calling C<close> explicitly or by any other means, |
|
|
1017 | such as C<dup>). The reason is that you register interest in some file |
|
|
1018 | descriptor, but when it goes away, the operating system will silently drop |
|
|
1019 | this interest. If another file descriptor with the same number then is |
|
|
1020 | registered with libev, there is no efficient way to see that this is, in |
|
|
1021 | fact, a different file descriptor. |
|
|
1022 | |
|
|
1023 | To avoid having to explicitly tell libev about such cases, libev follows |
|
|
1024 | the following policy: Each time C<ev_io_set> is being called, libev |
|
|
1025 | will assume that this is potentially a new file descriptor, otherwise |
|
|
1026 | it is assumed that the file descriptor stays the same. That means that |
|
|
1027 | you I<have> to call C<ev_io_set> (or C<ev_io_init>) when you change the |
|
|
1028 | descriptor even if the file descriptor number itself did not change. |
|
|
1029 | |
|
|
1030 | This is how one would do it normally anyway, the important point is that |
|
|
1031 | the libev application should not optimise around libev but should leave |
|
|
1032 | optimisations to libev. |
|
|
1033 | |
|
|
1034 | =head3 The special problem of dup'ed file descriptors |
|
|
1035 | |
|
|
1036 | Some backends (e.g. epoll), cannot register events for file descriptors, |
|
|
1037 | but only events for the underlying file descriptions. That means when you |
|
|
1038 | have C<dup ()>'ed file descriptors and register events for them, only one |
|
|
1039 | file descriptor might actually receive events. |
|
|
1040 | |
|
|
1041 | There is no workaround possible except not registering events |
|
|
1042 | for potentially C<dup ()>'ed file descriptors, or to resort to |
|
|
1043 | C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>. |
|
|
1044 | |
|
|
1045 | =head3 The special problem of fork |
|
|
1046 | |
|
|
1047 | Some backends (epoll, kqueue) do not support C<fork ()> at all or exhibit |
|
|
1048 | useless behaviour. Libev fully supports fork, but needs to be told about |
|
|
1049 | it in the child. |
|
|
1050 | |
|
|
1051 | To support fork in your programs, you either have to call |
|
|
1052 | C<ev_default_fork ()> or C<ev_loop_fork ()> after a fork in the child, |
|
|
1053 | enable C<EVFLAG_FORKCHECK>, or resort to C<EVBACKEND_SELECT> or |
|
|
1054 | C<EVBACKEND_POLL>. |
|
|
1055 | |
|
|
1056 | |
|
|
1057 | =head3 Watcher-Specific Functions |
|
|
1058 | |
912 | =over 4 |
1059 | =over 4 |
913 | |
1060 | |
914 | =item ev_io_init (ev_io *, callback, int fd, int events) |
1061 | =item ev_io_init (ev_io *, callback, int fd, int events) |
915 | |
1062 | |
916 | =item ev_io_set (ev_io *, int fd, int events) |
1063 | =item ev_io_set (ev_io *, int fd, int events) |
… | |
… | |
968 | ev_timer_set (&timer, after + ev_now () - ev_time (), 0.); |
1115 | ev_timer_set (&timer, after + ev_now () - ev_time (), 0.); |
969 | |
1116 | |
970 | The callback is guarenteed to be invoked only when its timeout has passed, |
1117 | The callback is guarenteed to be invoked only when its timeout has passed, |
971 | but if multiple timers become ready during the same loop iteration then |
1118 | but if multiple timers become ready during the same loop iteration then |
972 | order of execution is undefined. |
1119 | order of execution is undefined. |
|
|
1120 | |
|
|
1121 | =head3 Watcher-Specific Functions and Data Members |
973 | |
1122 | |
974 | =over 4 |
1123 | =over 4 |
975 | |
1124 | |
976 | =item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat) |
1125 | =item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat) |
977 | |
1126 | |
… | |
… | |
1073 | but on wallclock time (absolute time). You can tell a periodic watcher |
1222 | but on wallclock time (absolute time). You can tell a periodic watcher |
1074 | to trigger "at" some specific point in time. For example, if you tell a |
1223 | to trigger "at" some specific point in time. For example, if you tell a |
1075 | periodic watcher to trigger in 10 seconds (by specifiying e.g. C<ev_now () |
1224 | periodic watcher to trigger in 10 seconds (by specifiying e.g. C<ev_now () |
1076 | + 10.>) and then reset your system clock to the last year, then it will |
1225 | + 10.>) and then reset your system clock to the last year, then it will |
1077 | take a year to trigger the event (unlike an C<ev_timer>, which would trigger |
1226 | take a year to trigger the event (unlike an C<ev_timer>, which would trigger |
1078 | roughly 10 seconds later and of course not if you reset your system time |
1227 | roughly 10 seconds later). |
1079 | again). |
|
|
1080 | |
1228 | |
1081 | They can also be used to implement vastly more complex timers, such as |
1229 | They can also be used to implement vastly more complex timers, such as |
1082 | triggering an event on eahc midnight, local time. |
1230 | triggering an event on each midnight, local time or other, complicated, |
|
|
1231 | rules. |
1083 | |
1232 | |
1084 | As with timers, the callback is guarenteed to be invoked only when the |
1233 | As with timers, the callback is guarenteed to be invoked only when the |
1085 | time (C<at>) has been passed, but if multiple periodic timers become ready |
1234 | time (C<at>) has been passed, but if multiple periodic timers become ready |
1086 | during the same loop iteration then order of execution is undefined. |
1235 | during the same loop iteration then order of execution is undefined. |
1087 | |
1236 | |
|
|
1237 | =head3 Watcher-Specific Functions and Data Members |
|
|
1238 | |
1088 | =over 4 |
1239 | =over 4 |
1089 | |
1240 | |
1090 | =item ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb) |
1241 | =item ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb) |
1091 | |
1242 | |
1092 | =item ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb) |
1243 | =item ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb) |
… | |
… | |
1094 | Lots of arguments, lets sort it out... There are basically three modes of |
1245 | Lots of arguments, lets sort it out... There are basically three modes of |
1095 | operation, and we will explain them from simplest to complex: |
1246 | operation, and we will explain them from simplest to complex: |
1096 | |
1247 | |
1097 | =over 4 |
1248 | =over 4 |
1098 | |
1249 | |
1099 | =item * absolute timer (interval = reschedule_cb = 0) |
1250 | =item * absolute timer (at = time, interval = reschedule_cb = 0) |
1100 | |
1251 | |
1101 | In this configuration the watcher triggers an event at the wallclock time |
1252 | In this configuration the watcher triggers an event at the wallclock time |
1102 | C<at> and doesn't repeat. It will not adjust when a time jump occurs, |
1253 | C<at> and doesn't repeat. It will not adjust when a time jump occurs, |
1103 | that is, if it is to be run at January 1st 2011 then it will run when the |
1254 | that is, if it is to be run at January 1st 2011 then it will run when the |
1104 | system time reaches or surpasses this time. |
1255 | system time reaches or surpasses this time. |
1105 | |
1256 | |
1106 | =item * non-repeating interval timer (interval > 0, reschedule_cb = 0) |
1257 | =item * non-repeating interval timer (at = offset, interval > 0, reschedule_cb = 0) |
1107 | |
1258 | |
1108 | In this mode the watcher will always be scheduled to time out at the next |
1259 | In this mode the watcher will always be scheduled to time out at the next |
1109 | C<at + N * interval> time (for some integer N) and then repeat, regardless |
1260 | C<at + N * interval> time (for some integer N, which can also be negative) |
1110 | of any time jumps. |
1261 | and then repeat, regardless of any time jumps. |
1111 | |
1262 | |
1112 | This can be used to create timers that do not drift with respect to system |
1263 | This can be used to create timers that do not drift with respect to system |
1113 | time: |
1264 | time: |
1114 | |
1265 | |
1115 | ev_periodic_set (&periodic, 0., 3600., 0); |
1266 | ev_periodic_set (&periodic, 0., 3600., 0); |
… | |
… | |
1121 | |
1272 | |
1122 | Another way to think about it (for the mathematically inclined) is that |
1273 | Another way to think about it (for the mathematically inclined) is that |
1123 | C<ev_periodic> will try to run the callback in this mode at the next possible |
1274 | C<ev_periodic> will try to run the callback in this mode at the next possible |
1124 | time where C<time = at (mod interval)>, regardless of any time jumps. |
1275 | time where C<time = at (mod interval)>, regardless of any time jumps. |
1125 | |
1276 | |
|
|
1277 | For numerical stability it is preferable that the C<at> value is near |
|
|
1278 | C<ev_now ()> (the current time), but there is no range requirement for |
|
|
1279 | this value. |
|
|
1280 | |
1126 | =item * manual reschedule mode (reschedule_cb = callback) |
1281 | =item * manual reschedule mode (at and interval ignored, reschedule_cb = callback) |
1127 | |
1282 | |
1128 | In this mode the values for C<interval> and C<at> are both being |
1283 | In this mode the values for C<interval> and C<at> are both being |
1129 | ignored. Instead, each time the periodic watcher gets scheduled, the |
1284 | ignored. Instead, each time the periodic watcher gets scheduled, the |
1130 | reschedule callback will be called with the watcher as first, and the |
1285 | reschedule callback will be called with the watcher as first, and the |
1131 | current time as second argument. |
1286 | current time as second argument. |
1132 | |
1287 | |
1133 | NOTE: I<This callback MUST NOT stop or destroy any periodic watcher, |
1288 | NOTE: I<This callback MUST NOT stop or destroy any periodic watcher, |
1134 | ever, or make any event loop modifications>. If you need to stop it, |
1289 | ever, or make any event loop modifications>. If you need to stop it, |
1135 | return C<now + 1e30> (or so, fudge fudge) and stop it afterwards (e.g. by |
1290 | return C<now + 1e30> (or so, fudge fudge) and stop it afterwards (e.g. by |
1136 | starting a prepare watcher). |
1291 | starting an C<ev_prepare> watcher, which is legal). |
1137 | |
1292 | |
1138 | Its prototype is C<ev_tstamp (*reschedule_cb)(struct ev_periodic *w, |
1293 | Its prototype is C<ev_tstamp (*reschedule_cb)(struct ev_periodic *w, |
1139 | ev_tstamp now)>, e.g.: |
1294 | ev_tstamp now)>, e.g.: |
1140 | |
1295 | |
1141 | static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now) |
1296 | static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now) |
… | |
… | |
1164 | Simply stops and restarts the periodic watcher again. This is only useful |
1319 | Simply stops and restarts the periodic watcher again. This is only useful |
1165 | when you changed some parameters or the reschedule callback would return |
1320 | when you changed some parameters or the reschedule callback would return |
1166 | a different time than the last time it was called (e.g. in a crond like |
1321 | a different time than the last time it was called (e.g. in a crond like |
1167 | program when the crontabs have changed). |
1322 | program when the crontabs have changed). |
1168 | |
1323 | |
|
|
1324 | =item ev_tstamp offset [read-write] |
|
|
1325 | |
|
|
1326 | When repeating, this contains the offset value, otherwise this is the |
|
|
1327 | absolute point in time (the C<at> value passed to C<ev_periodic_set>). |
|
|
1328 | |
|
|
1329 | Can be modified any time, but changes only take effect when the periodic |
|
|
1330 | timer fires or C<ev_periodic_again> is being called. |
|
|
1331 | |
1169 | =item ev_tstamp interval [read-write] |
1332 | =item ev_tstamp interval [read-write] |
1170 | |
1333 | |
1171 | The current interval value. Can be modified any time, but changes only |
1334 | The current interval value. Can be modified any time, but changes only |
1172 | take effect when the periodic timer fires or C<ev_periodic_again> is being |
1335 | take effect when the periodic timer fires or C<ev_periodic_again> is being |
1173 | called. |
1336 | called. |
… | |
… | |
1175 | =item ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read-write] |
1338 | =item ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read-write] |
1176 | |
1339 | |
1177 | The current reschedule callback, or C<0>, if this functionality is |
1340 | The current reschedule callback, or C<0>, if this functionality is |
1178 | switched off. Can be changed any time, but changes only take effect when |
1341 | switched off. Can be changed any time, but changes only take effect when |
1179 | the periodic timer fires or C<ev_periodic_again> is being called. |
1342 | the periodic timer fires or C<ev_periodic_again> is being called. |
|
|
1343 | |
|
|
1344 | =item ev_tstamp at [read-only] |
|
|
1345 | |
|
|
1346 | When active, contains the absolute time that the watcher is supposed to |
|
|
1347 | trigger next. |
1180 | |
1348 | |
1181 | =back |
1349 | =back |
1182 | |
1350 | |
1183 | Example: Call a callback every hour, or, more precisely, whenever the |
1351 | Example: Call a callback every hour, or, more precisely, whenever the |
1184 | system clock is divisible by 3600. The callback invocation times have |
1352 | system clock is divisible by 3600. The callback invocation times have |
… | |
… | |
1226 | with the kernel (thus it coexists with your own signal handlers as long |
1394 | with the kernel (thus it coexists with your own signal handlers as long |
1227 | as you don't register any with libev). Similarly, when the last signal |
1395 | as you don't register any with libev). Similarly, when the last signal |
1228 | watcher for a signal is stopped libev will reset the signal handler to |
1396 | watcher for a signal is stopped libev will reset the signal handler to |
1229 | SIG_DFL (regardless of what it was set to before). |
1397 | SIG_DFL (regardless of what it was set to before). |
1230 | |
1398 | |
|
|
1399 | =head3 Watcher-Specific Functions and Data Members |
|
|
1400 | |
1231 | =over 4 |
1401 | =over 4 |
1232 | |
1402 | |
1233 | =item ev_signal_init (ev_signal *, callback, int signum) |
1403 | =item ev_signal_init (ev_signal *, callback, int signum) |
1234 | |
1404 | |
1235 | =item ev_signal_set (ev_signal *, int signum) |
1405 | =item ev_signal_set (ev_signal *, int signum) |
… | |
… | |
1246 | |
1416 | |
1247 | =head2 C<ev_child> - watch out for process status changes |
1417 | =head2 C<ev_child> - watch out for process status changes |
1248 | |
1418 | |
1249 | Child watchers trigger when your process receives a SIGCHLD in response to |
1419 | Child watchers trigger when your process receives a SIGCHLD in response to |
1250 | some child status changes (most typically when a child of yours dies). |
1420 | some child status changes (most typically when a child of yours dies). |
|
|
1421 | |
|
|
1422 | =head3 Watcher-Specific Functions and Data Members |
1251 | |
1423 | |
1252 | =over 4 |
1424 | =over 4 |
1253 | |
1425 | |
1254 | =item ev_child_init (ev_child *, callback, int pid) |
1426 | =item ev_child_init (ev_child *, callback, int pid) |
1255 | |
1427 | |
… | |
… | |
1323 | reader). Inotify will be used to give hints only and should not change the |
1495 | reader). Inotify will be used to give hints only and should not change the |
1324 | semantics of C<ev_stat> watchers, which means that libev sometimes needs |
1496 | semantics of C<ev_stat> watchers, which means that libev sometimes needs |
1325 | to fall back to regular polling again even with inotify, but changes are |
1497 | to fall back to regular polling again even with inotify, but changes are |
1326 | usually detected immediately, and if the file exists there will be no |
1498 | usually detected immediately, and if the file exists there will be no |
1327 | polling. |
1499 | polling. |
|
|
1500 | |
|
|
1501 | =head3 The special problem of stat time resolution |
|
|
1502 | |
|
|
1503 | The C<stat ()> syscall only supports full-second resolution portably, and |
|
|
1504 | even on systems where the resolution is higher, many filesystems still |
|
|
1505 | only support whole seconds. |
|
|
1506 | |
|
|
1507 | That means that, if the time is the only thing that changes, you might |
|
|
1508 | miss updates: on the first update, C<ev_stat> detects a change and calls |
|
|
1509 | your callback, which does something. When there is another update within |
|
|
1510 | the same second, C<ev_stat> will be unable to detect it. |
|
|
1511 | |
|
|
1512 | The solution to this is to delay acting on a change for a second (or till |
|
|
1513 | the next second boundary), using a roughly one-second delay C<ev_timer> |
|
|
1514 | (C<ev_timer_set (w, 0., 1.01); ev_timer_again (loop, w)>). The C<.01> |
|
|
1515 | is added to work around small timing inconsistencies of some operating |
|
|
1516 | systems. |
|
|
1517 | |
|
|
1518 | =head3 Watcher-Specific Functions and Data Members |
1328 | |
1519 | |
1329 | =over 4 |
1520 | =over 4 |
1330 | |
1521 | |
1331 | =item ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval) |
1522 | =item ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval) |
1332 | |
1523 | |
… | |
… | |
1390 | } |
1581 | } |
1391 | |
1582 | |
1392 | ... |
1583 | ... |
1393 | ev_stat passwd; |
1584 | ev_stat passwd; |
1394 | |
1585 | |
1395 | ev_stat_init (&passwd, passwd_cb, "/etc/passwd"); |
1586 | ev_stat_init (&passwd, passwd_cb, "/etc/passwd", 0.); |
1396 | ev_stat_start (loop, &passwd); |
1587 | ev_stat_start (loop, &passwd); |
|
|
1588 | |
|
|
1589 | Example: Like above, but additionally use a one-second delay so we do not |
|
|
1590 | miss updates (however, frequent updates will delay processing, too, so |
|
|
1591 | one might do the work both on C<ev_stat> callback invocation I<and> on |
|
|
1592 | C<ev_timer> callback invocation). |
|
|
1593 | |
|
|
1594 | static ev_stat passwd; |
|
|
1595 | static ev_timer timer; |
|
|
1596 | |
|
|
1597 | static void |
|
|
1598 | timer_cb (EV_P_ ev_timer *w, int revents) |
|
|
1599 | { |
|
|
1600 | ev_timer_stop (EV_A_ w); |
|
|
1601 | |
|
|
1602 | /* now it's one second after the most recent passwd change */ |
|
|
1603 | } |
|
|
1604 | |
|
|
1605 | static void |
|
|
1606 | stat_cb (EV_P_ ev_stat *w, int revents) |
|
|
1607 | { |
|
|
1608 | /* reset the one-second timer */ |
|
|
1609 | ev_timer_again (EV_A_ &timer); |
|
|
1610 | } |
|
|
1611 | |
|
|
1612 | ... |
|
|
1613 | ev_stat_init (&passwd, stat_cb, "/etc/passwd", 0.); |
|
|
1614 | ev_stat_start (loop, &passwd); |
|
|
1615 | ev_timer_init (&timer, timer_cb, 0., 1.01); |
1397 | |
1616 | |
1398 | |
1617 | |
1399 | =head2 C<ev_idle> - when you've got nothing better to do... |
1618 | =head2 C<ev_idle> - when you've got nothing better to do... |
1400 | |
1619 | |
1401 | Idle watchers trigger events when no other events of the same or higher |
1620 | Idle watchers trigger events when no other events of the same or higher |
… | |
… | |
1414 | |
1633 | |
1415 | Apart from keeping your process non-blocking (which is a useful |
1634 | Apart from keeping your process non-blocking (which is a useful |
1416 | effect on its own sometimes), idle watchers are a good place to do |
1635 | effect on its own sometimes), idle watchers are a good place to do |
1417 | "pseudo-background processing", or delay processing stuff to after the |
1636 | "pseudo-background processing", or delay processing stuff to after the |
1418 | event loop has handled all outstanding events. |
1637 | event loop has handled all outstanding events. |
|
|
1638 | |
|
|
1639 | =head3 Watcher-Specific Functions and Data Members |
1419 | |
1640 | |
1420 | =over 4 |
1641 | =over 4 |
1421 | |
1642 | |
1422 | =item ev_idle_init (ev_signal *, callback) |
1643 | =item ev_idle_init (ev_signal *, callback) |
1423 | |
1644 | |
… | |
… | |
1480 | are ready to run (it's actually more complicated: it only runs coroutines |
1701 | are ready to run (it's actually more complicated: it only runs coroutines |
1481 | with priority higher than or equal to the event loop and one coroutine |
1702 | with priority higher than or equal to the event loop and one coroutine |
1482 | of lower priority, but only once, using idle watchers to keep the event |
1703 | of lower priority, but only once, using idle watchers to keep the event |
1483 | loop from blocking if lower-priority coroutines are active, thus mapping |
1704 | loop from blocking if lower-priority coroutines are active, thus mapping |
1484 | low-priority coroutines to idle/background tasks). |
1705 | low-priority coroutines to idle/background tasks). |
|
|
1706 | |
|
|
1707 | It is recommended to give C<ev_check> watchers highest (C<EV_MAXPRI>) |
|
|
1708 | priority, to ensure that they are being run before any other watchers |
|
|
1709 | after the poll. Also, C<ev_check> watchers (and C<ev_prepare> watchers, |
|
|
1710 | too) should not activate ("feed") events into libev. While libev fully |
|
|
1711 | supports this, they will be called before other C<ev_check> watchers |
|
|
1712 | did their job. As C<ev_check> watchers are often used to embed other |
|
|
1713 | (non-libev) event loops those other event loops might be in an unusable |
|
|
1714 | state until their C<ev_check> watcher ran (always remind yourself to |
|
|
1715 | coexist peacefully with others). |
|
|
1716 | |
|
|
1717 | =head3 Watcher-Specific Functions and Data Members |
1485 | |
1718 | |
1486 | =over 4 |
1719 | =over 4 |
1487 | |
1720 | |
1488 | =item ev_prepare_init (ev_prepare *, callback) |
1721 | =item ev_prepare_init (ev_prepare *, callback) |
1489 | |
1722 | |
… | |
… | |
1691 | ev_embed_start (loop_hi, &embed); |
1924 | ev_embed_start (loop_hi, &embed); |
1692 | } |
1925 | } |
1693 | else |
1926 | else |
1694 | loop_lo = loop_hi; |
1927 | loop_lo = loop_hi; |
1695 | |
1928 | |
|
|
1929 | =head3 Watcher-Specific Functions and Data Members |
|
|
1930 | |
1696 | =over 4 |
1931 | =over 4 |
1697 | |
1932 | |
1698 | =item ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop) |
1933 | =item ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop) |
1699 | |
1934 | |
1700 | =item ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop) |
1935 | =item ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop) |
… | |
… | |
1709 | |
1944 | |
1710 | Make a single, non-blocking sweep over the embedded loop. This works |
1945 | Make a single, non-blocking sweep over the embedded loop. This works |
1711 | similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most |
1946 | similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most |
1712 | apropriate way for embedded loops. |
1947 | apropriate way for embedded loops. |
1713 | |
1948 | |
1714 | =item struct ev_loop *loop [read-only] |
1949 | =item struct ev_loop *other [read-only] |
1715 | |
1950 | |
1716 | The embedded event loop. |
1951 | The embedded event loop. |
1717 | |
1952 | |
1718 | =back |
1953 | =back |
1719 | |
1954 | |
… | |
… | |
1726 | event loop blocks next and before C<ev_check> watchers are being called, |
1961 | event loop blocks next and before C<ev_check> watchers are being called, |
1727 | and only in the child after the fork. If whoever good citizen calling |
1962 | and only in the child after the fork. If whoever good citizen calling |
1728 | C<ev_default_fork> cheats and calls it in the wrong process, the fork |
1963 | C<ev_default_fork> cheats and calls it in the wrong process, the fork |
1729 | handlers will be invoked, too, of course. |
1964 | handlers will be invoked, too, of course. |
1730 | |
1965 | |
|
|
1966 | =head3 Watcher-Specific Functions and Data Members |
|
|
1967 | |
1731 | =over 4 |
1968 | =over 4 |
1732 | |
1969 | |
1733 | =item ev_fork_init (ev_signal *, callback) |
1970 | =item ev_fork_init (ev_signal *, callback) |
1734 | |
1971 | |
1735 | Initialises and configures the fork watcher - it has no parameters of any |
1972 | Initialises and configures the fork watcher - it has no parameters of any |
… | |
… | |
1951 | |
2188 | |
1952 | =item w->stop () |
2189 | =item w->stop () |
1953 | |
2190 | |
1954 | Stops the watcher if it is active. Again, no C<loop> argument. |
2191 | Stops the watcher if it is active. Again, no C<loop> argument. |
1955 | |
2192 | |
1956 | =item w->again () C<ev::timer>, C<ev::periodic> only |
2193 | =item w->again () (C<ev::timer>, C<ev::periodic> only) |
1957 | |
2194 | |
1958 | For C<ev::timer> and C<ev::periodic>, this invokes the corresponding |
2195 | For C<ev::timer> and C<ev::periodic>, this invokes the corresponding |
1959 | C<ev_TYPE_again> function. |
2196 | C<ev_TYPE_again> function. |
1960 | |
2197 | |
1961 | =item w->sweep () C<ev::embed> only |
2198 | =item w->sweep () (C<ev::embed> only) |
1962 | |
2199 | |
1963 | Invokes C<ev_embed_sweep>. |
2200 | Invokes C<ev_embed_sweep>. |
1964 | |
2201 | |
1965 | =item w->update () C<ev::stat> only |
2202 | =item w->update () (C<ev::stat> only) |
1966 | |
2203 | |
1967 | Invokes C<ev_stat_stat>. |
2204 | Invokes C<ev_stat_stat>. |
1968 | |
2205 | |
1969 | =back |
2206 | =back |
1970 | |
2207 | |
… | |
… | |
1990 | } |
2227 | } |
1991 | |
2228 | |
1992 | |
2229 | |
1993 | =head1 MACRO MAGIC |
2230 | =head1 MACRO MAGIC |
1994 | |
2231 | |
1995 | Libev can be compiled with a variety of options, the most fundemantal is |
2232 | Libev can be compiled with a variety of options, the most fundamantal |
1996 | C<EV_MULTIPLICITY>. This option determines whether (most) functions and |
2233 | of which is C<EV_MULTIPLICITY>. This option determines whether (most) |
1997 | callbacks have an initial C<struct ev_loop *> argument. |
2234 | functions and callbacks have an initial C<struct ev_loop *> argument. |
1998 | |
2235 | |
1999 | To make it easier to write programs that cope with either variant, the |
2236 | To make it easier to write programs that cope with either variant, the |
2000 | following macros are defined: |
2237 | following macros are defined: |
2001 | |
2238 | |
2002 | =over 4 |
2239 | =over 4 |
… | |
… | |
2056 | Libev can (and often is) directly embedded into host |
2293 | Libev can (and often is) directly embedded into host |
2057 | applications. Examples of applications that embed it include the Deliantra |
2294 | applications. Examples of applications that embed it include the Deliantra |
2058 | Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe) |
2295 | Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe) |
2059 | and rxvt-unicode. |
2296 | and rxvt-unicode. |
2060 | |
2297 | |
2061 | The goal is to enable you to just copy the neecssary files into your |
2298 | The goal is to enable you to just copy the necessary files into your |
2062 | source directory without having to change even a single line in them, so |
2299 | source directory without having to change even a single line in them, so |
2063 | you can easily upgrade by simply copying (or having a checked-out copy of |
2300 | you can easily upgrade by simply copying (or having a checked-out copy of |
2064 | libev somewhere in your source tree). |
2301 | libev somewhere in your source tree). |
2065 | |
2302 | |
2066 | =head2 FILESETS |
2303 | =head2 FILESETS |
… | |
… | |
2156 | |
2393 | |
2157 | If defined to be C<1>, libev will try to detect the availability of the |
2394 | If defined to be C<1>, libev will try to detect the availability of the |
2158 | monotonic clock option at both compiletime and runtime. Otherwise no use |
2395 | monotonic clock option at both compiletime and runtime. Otherwise no use |
2159 | of the monotonic clock option will be attempted. If you enable this, you |
2396 | of the monotonic clock option will be attempted. If you enable this, you |
2160 | usually have to link against librt or something similar. Enabling it when |
2397 | usually have to link against librt or something similar. Enabling it when |
2161 | the functionality isn't available is safe, though, althoguh you have |
2398 | the functionality isn't available is safe, though, although you have |
2162 | to make sure you link against any libraries where the C<clock_gettime> |
2399 | to make sure you link against any libraries where the C<clock_gettime> |
2163 | function is hiding in (often F<-lrt>). |
2400 | function is hiding in (often F<-lrt>). |
2164 | |
2401 | |
2165 | =item EV_USE_REALTIME |
2402 | =item EV_USE_REALTIME |
2166 | |
2403 | |
2167 | If defined to be C<1>, libev will try to detect the availability of the |
2404 | If defined to be C<1>, libev will try to detect the availability of the |
2168 | realtime clock option at compiletime (and assume its availability at |
2405 | realtime clock option at compiletime (and assume its availability at |
2169 | runtime if successful). Otherwise no use of the realtime clock option will |
2406 | runtime if successful). Otherwise no use of the realtime clock option will |
2170 | be attempted. This effectively replaces C<gettimeofday> by C<clock_get |
2407 | be attempted. This effectively replaces C<gettimeofday> by C<clock_get |
2171 | (CLOCK_REALTIME, ...)> and will not normally affect correctness. See tzhe note about libraries |
2408 | (CLOCK_REALTIME, ...)> and will not normally affect correctness. See the |
2172 | in the description of C<EV_USE_MONOTONIC>, though. |
2409 | note about libraries in the description of C<EV_USE_MONOTONIC>, though. |
|
|
2410 | |
|
|
2411 | =item EV_USE_NANOSLEEP |
|
|
2412 | |
|
|
2413 | If defined to be C<1>, libev will assume that C<nanosleep ()> is available |
|
|
2414 | and will use it for delays. Otherwise it will use C<select ()>. |
2173 | |
2415 | |
2174 | =item EV_USE_SELECT |
2416 | =item EV_USE_SELECT |
2175 | |
2417 | |
2176 | If undefined or defined to be C<1>, libev will compile in support for the |
2418 | If undefined or defined to be C<1>, libev will compile in support for the |
2177 | C<select>(2) backend. No attempt at autodetection will be done: if no |
2419 | C<select>(2) backend. No attempt at autodetection will be done: if no |
… | |
… | |
2329 | than enough. If you need to manage thousands of children you might want to |
2571 | than enough. If you need to manage thousands of children you might want to |
2330 | increase this value (I<must> be a power of two). |
2572 | increase this value (I<must> be a power of two). |
2331 | |
2573 | |
2332 | =item EV_INOTIFY_HASHSIZE |
2574 | =item EV_INOTIFY_HASHSIZE |
2333 | |
2575 | |
2334 | C<ev_staz> watchers use a small hash table to distribute workload by |
2576 | C<ev_stat> watchers use a small hash table to distribute workload by |
2335 | inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>), |
2577 | inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>), |
2336 | usually more than enough. If you need to manage thousands of C<ev_stat> |
2578 | usually more than enough. If you need to manage thousands of C<ev_stat> |
2337 | watchers you might want to increase this value (I<must> be a power of |
2579 | watchers you might want to increase this value (I<must> be a power of |
2338 | two). |
2580 | two). |
2339 | |
2581 | |
… | |
… | |
2356 | |
2598 | |
2357 | =item ev_set_cb (ev, cb) |
2599 | =item ev_set_cb (ev, cb) |
2358 | |
2600 | |
2359 | Can be used to change the callback member declaration in each watcher, |
2601 | Can be used to change the callback member declaration in each watcher, |
2360 | and the way callbacks are invoked and set. Must expand to a struct member |
2602 | and the way callbacks are invoked and set. Must expand to a struct member |
2361 | definition and a statement, respectively. See the F<ev.v> header file for |
2603 | definition and a statement, respectively. See the F<ev.h> header file for |
2362 | their default definitions. One possible use for overriding these is to |
2604 | their default definitions. One possible use for overriding these is to |
2363 | avoid the C<struct ev_loop *> as first argument in all cases, or to use |
2605 | avoid the C<struct ev_loop *> as first argument in all cases, or to use |
2364 | method calls instead of plain function calls in C++. |
2606 | method calls instead of plain function calls in C++. |
|
|
2607 | |
|
|
2608 | =head2 EXPORTED API SYMBOLS |
|
|
2609 | |
|
|
2610 | If you need to re-export the API (e.g. via a dll) and you need a list of |
|
|
2611 | exported symbols, you can use the provided F<Symbol.*> files which list |
|
|
2612 | all public symbols, one per line: |
|
|
2613 | |
|
|
2614 | Symbols.ev for libev proper |
|
|
2615 | Symbols.event for the libevent emulation |
|
|
2616 | |
|
|
2617 | This can also be used to rename all public symbols to avoid clashes with |
|
|
2618 | multiple versions of libev linked together (which is obviously bad in |
|
|
2619 | itself, but sometimes it is inconvinient to avoid this). |
|
|
2620 | |
|
|
2621 | A sed command like this will create wrapper C<#define>'s that you need to |
|
|
2622 | include before including F<ev.h>: |
|
|
2623 | |
|
|
2624 | <Symbols.ev sed -e "s/.*/#define & myprefix_&/" >wrap.h |
|
|
2625 | |
|
|
2626 | This would create a file F<wrap.h> which essentially looks like this: |
|
|
2627 | |
|
|
2628 | #define ev_backend myprefix_ev_backend |
|
|
2629 | #define ev_check_start myprefix_ev_check_start |
|
|
2630 | #define ev_check_stop myprefix_ev_check_stop |
|
|
2631 | ... |
2365 | |
2632 | |
2366 | =head2 EXAMPLES |
2633 | =head2 EXAMPLES |
2367 | |
2634 | |
2368 | For a real-world example of a program the includes libev |
2635 | For a real-world example of a program the includes libev |
2369 | verbatim, you can have a look at the EV perl module |
2636 | verbatim, you can have a look at the EV perl module |
… | |
… | |
2410 | |
2677 | |
2411 | =item Starting and stopping timer/periodic watchers: O(log skipped_other_timers) |
2678 | =item Starting and stopping timer/periodic watchers: O(log skipped_other_timers) |
2412 | |
2679 | |
2413 | This means that, when you have a watcher that triggers in one hour and |
2680 | This means that, when you have a watcher that triggers in one hour and |
2414 | there are 100 watchers that would trigger before that then inserting will |
2681 | there are 100 watchers that would trigger before that then inserting will |
2415 | have to skip those 100 watchers. |
2682 | have to skip roughly seven (C<ld 100>) of these watchers. |
2416 | |
2683 | |
2417 | =item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers) |
2684 | =item Changing timer/periodic watchers (by autorepeat or calling again): O(log skipped_other_timers) |
2418 | |
2685 | |
2419 | That means that for changing a timer costs less than removing/adding them |
2686 | That means that changing a timer costs less than removing/adding them |
2420 | as only the relative motion in the event queue has to be paid for. |
2687 | as only the relative motion in the event queue has to be paid for. |
2421 | |
2688 | |
2422 | =item Starting io/check/prepare/idle/signal/child watchers: O(1) |
2689 | =item Starting io/check/prepare/idle/signal/child watchers: O(1) |
2423 | |
2690 | |
2424 | These just add the watcher into an array or at the head of a list. |
2691 | These just add the watcher into an array or at the head of a list. |
|
|
2692 | |
2425 | =item Stopping check/prepare/idle watchers: O(1) |
2693 | =item Stopping check/prepare/idle watchers: O(1) |
2426 | |
2694 | |
2427 | =item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE)) |
2695 | =item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE)) |
2428 | |
2696 | |
2429 | These watchers are stored in lists then need to be walked to find the |
2697 | These watchers are stored in lists then need to be walked to find the |
2430 | correct watcher to remove. The lists are usually short (you don't usually |
2698 | correct watcher to remove. The lists are usually short (you don't usually |
2431 | have many watchers waiting for the same fd or signal). |
2699 | have many watchers waiting for the same fd or signal). |
2432 | |
2700 | |
2433 | =item Finding the next timer per loop iteration: O(1) |
2701 | =item Finding the next timer in each loop iteration: O(1) |
|
|
2702 | |
|
|
2703 | By virtue of using a binary heap, the next timer is always found at the |
|
|
2704 | beginning of the storage array. |
2434 | |
2705 | |
2435 | =item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd) |
2706 | =item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd) |
2436 | |
2707 | |
2437 | A change means an I/O watcher gets started or stopped, which requires |
2708 | A change means an I/O watcher gets started or stopped, which requires |
2438 | libev to recalculate its status (and possibly tell the kernel). |
2709 | libev to recalculate its status (and possibly tell the kernel, depending |
|
|
2710 | on backend and wether C<ev_io_set> was used). |
2439 | |
2711 | |
2440 | =item Activating one watcher: O(1) |
2712 | =item Activating one watcher (putting it into the pending state): O(1) |
2441 | |
2713 | |
2442 | =item Priority handling: O(number_of_priorities) |
2714 | =item Priority handling: O(number_of_priorities) |
2443 | |
2715 | |
2444 | Priorities are implemented by allocating some space for each |
2716 | Priorities are implemented by allocating some space for each |
2445 | priority. When doing priority-based operations, libev usually has to |
2717 | priority. When doing priority-based operations, libev usually has to |
2446 | linearly search all the priorities. |
2718 | linearly search all the priorities, but starting/stopping and activating |
|
|
2719 | watchers becomes O(1) w.r.t. prioritiy handling. |
2447 | |
2720 | |
2448 | =back |
2721 | =back |
2449 | |
2722 | |
2450 | |
2723 | |
2451 | =head1 AUTHOR |
2724 | =head1 AUTHOR |