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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; |
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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 |
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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. |
… | |
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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 |
… | |
… | |
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 | |
491 | - Before the first iteration, call any pending watchers. |
555 | - Before the first iteration, call any pending watchers. |
492 | * If there are no active watchers (reference count is zero), return. |
556 | * If EVFLAG_FORKCHECK was used, check for a fork. |
493 | - Queue all prepare watchers and then call all outstanding watchers. |
557 | - If a fork was detected, queue and call all fork watchers. |
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558 | - Queue and call all prepare watchers. |
494 | - If we have been forked, recreate the kernel state. |
559 | - If we have been forked, recreate the kernel state. |
495 | - Update the kernel state with all outstanding changes. |
560 | - Update the kernel state with all outstanding changes. |
496 | - Update the "event loop time". |
561 | - Update the "event loop time". |
497 | - Calculate for how long to block. |
562 | - Calculate for how long to sleep or block, if at all |
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563 | (active idle watchers, EVLOOP_NONBLOCK or not having |
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564 | any active watchers at all will result in not sleeping). |
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565 | - Sleep if the I/O and timer collect interval say so. |
498 | - Block the process, waiting for any events. |
566 | - Block the process, waiting for any events. |
499 | - Queue all outstanding I/O (fd) events. |
567 | - Queue all outstanding I/O (fd) events. |
500 | - Update the "event loop time" and do time jump handling. |
568 | - Update the "event loop time" and do time jump handling. |
501 | - Queue all outstanding timers. |
569 | - Queue all outstanding timers. |
502 | - Queue all outstanding periodics. |
570 | - Queue all outstanding periodics. |
503 | - If no events are pending now, queue all idle watchers. |
571 | - If no events are pending now, queue all idle watchers. |
504 | - Queue all check watchers. |
572 | - Queue all check watchers. |
505 | - Call all queued watchers in reverse order (i.e. check watchers first). |
573 | - Call all queued watchers in reverse order (i.e. check watchers first). |
506 | Signals and child watchers are implemented as I/O watchers, and will |
574 | Signals and child watchers are implemented as I/O watchers, and will |
507 | be handled here by queueing them when their watcher gets executed. |
575 | be handled here by queueing them when their watcher gets executed. |
508 | - If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
576 | - If ev_unloop has been called, or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
509 | were used, return, otherwise continue with step *. |
577 | were used, or there are no active watchers, return, otherwise |
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578 | continue with step *. |
510 | |
579 | |
511 | Example: Queue some jobs and then loop until no events are outsanding |
580 | Example: Queue some jobs and then loop until no events are outstanding |
512 | anymore. |
581 | anymore. |
513 | |
582 | |
514 | ... queue jobs here, make sure they register event watchers as long |
583 | ... queue jobs here, make sure they register event watchers as long |
515 | ... as they still have work to do (even an idle watcher will do..) |
584 | ... as they still have work to do (even an idle watcher will do..) |
516 | ev_loop (my_loop, 0); |
585 | ev_loop (my_loop, 0); |
… | |
… | |
549 | Example: For some weird reason, unregister the above signal handler again. |
618 | Example: For some weird reason, unregister the above signal handler again. |
550 | |
619 | |
551 | ev_ref (loop); |
620 | ev_ref (loop); |
552 | ev_signal_stop (loop, &exitsig); |
621 | ev_signal_stop (loop, &exitsig); |
553 | |
622 | |
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623 | =item ev_set_io_collect_interval (loop, ev_tstamp interval) |
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624 | |
|
|
625 | =item ev_set_timeout_collect_interval (loop, ev_tstamp interval) |
|
|
626 | |
|
|
627 | These advanced functions influence the time that libev will spend waiting |
|
|
628 | for events. Both are by default C<0>, meaning that libev will try to |
|
|
629 | invoke timer/periodic callbacks and I/O callbacks with minimum latency. |
|
|
630 | |
|
|
631 | Setting these to a higher value (the C<interval> I<must> be >= C<0>) |
|
|
632 | allows libev to delay invocation of I/O and timer/periodic callbacks to |
|
|
633 | increase efficiency of loop iterations. |
|
|
634 | |
|
|
635 | The background is that sometimes your program runs just fast enough to |
|
|
636 | handle one (or very few) event(s) per loop iteration. While this makes |
|
|
637 | the program responsive, it also wastes a lot of CPU time to poll for new |
|
|
638 | events, especially with backends like C<select ()> which have a high |
|
|
639 | overhead for the actual polling but can deliver many events at once. |
|
|
640 | |
|
|
641 | By setting a higher I<io collect interval> you allow libev to spend more |
|
|
642 | time collecting I/O events, so you can handle more events per iteration, |
|
|
643 | at the cost of increasing latency. Timeouts (both C<ev_periodic> and |
|
|
644 | C<ev_timer>) will be not affected. Setting this to a non-null value will |
|
|
645 | introduce an additional C<ev_sleep ()> call into most loop iterations. |
|
|
646 | |
|
|
647 | Likewise, by setting a higher I<timeout collect interval> you allow libev |
|
|
648 | to spend more time collecting timeouts, at the expense of increased |
|
|
649 | latency (the watcher callback will be called later). C<ev_io> watchers |
|
|
650 | will not be affected. Setting this to a non-null value will not introduce |
|
|
651 | any overhead in libev. |
|
|
652 | |
|
|
653 | Many (busy) programs can usually benefit by setting the io collect |
|
|
654 | interval to a value near C<0.1> or so, which is often enough for |
|
|
655 | interactive servers (of course not for games), likewise for timeouts. It |
|
|
656 | usually doesn't make much sense to set it to a lower value than C<0.01>, |
|
|
657 | as this approsaches the timing granularity of most systems. |
|
|
658 | |
554 | =back |
659 | =back |
555 | |
660 | |
556 | |
661 | |
557 | =head1 ANATOMY OF A WATCHER |
662 | =head1 ANATOMY OF A WATCHER |
558 | |
663 | |
… | |
… | |
883 | In general you can register as many read and/or write event watchers per |
988 | In general you can register as many read and/or write event watchers per |
884 | fd as you want (as long as you don't confuse yourself). Setting all file |
989 | fd as you want (as long as you don't confuse yourself). Setting all file |
885 | descriptors to non-blocking mode is also usually a good idea (but not |
990 | descriptors to non-blocking mode is also usually a good idea (but not |
886 | required if you know what you are doing). |
991 | required if you know what you are doing). |
887 | |
992 | |
888 | You have to be careful with dup'ed file descriptors, though. Some backends |
|
|
889 | (the linux epoll backend is a notable example) cannot handle dup'ed file |
|
|
890 | descriptors correctly if you register interest in two or more fds pointing |
|
|
891 | to the same underlying file/socket/etc. description (that is, they share |
|
|
892 | the same underlying "file open"). |
|
|
893 | |
|
|
894 | If you must do this, then force the use of a known-to-be-good backend |
993 | If you must do this, then force the use of a known-to-be-good backend |
895 | (at the time of this writing, this includes only C<EVBACKEND_SELECT> and |
994 | (at the time of this writing, this includes only C<EVBACKEND_SELECT> and |
896 | C<EVBACKEND_POLL>). |
995 | C<EVBACKEND_POLL>). |
897 | |
996 | |
898 | Another thing you have to watch out for is that it is quite easy to |
997 | Another thing you have to watch out for is that it is quite easy to |
… | |
… | |
908 | play around with an Xlib connection), then you have to seperately re-test |
1007 | play around with an Xlib connection), then you have to seperately re-test |
909 | whether a file descriptor is really ready with a known-to-be good interface |
1008 | whether a file descriptor is really ready with a known-to-be good interface |
910 | such as poll (fortunately in our Xlib example, Xlib already does this on |
1009 | such as poll (fortunately in our Xlib example, Xlib already does this on |
911 | its own, so its quite safe to use). |
1010 | its own, so its quite safe to use). |
912 | |
1011 | |
|
|
1012 | =head3 The special problem of disappearing file descriptors |
|
|
1013 | |
|
|
1014 | Some backends (e.g. kqueue, epoll) need to be told about closing a file |
|
|
1015 | descriptor (either by calling C<close> explicitly or by any other means, |
|
|
1016 | such as C<dup>). The reason is that you register interest in some file |
|
|
1017 | descriptor, but when it goes away, the operating system will silently drop |
|
|
1018 | this interest. If another file descriptor with the same number then is |
|
|
1019 | registered with libev, there is no efficient way to see that this is, in |
|
|
1020 | fact, a different file descriptor. |
|
|
1021 | |
|
|
1022 | To avoid having to explicitly tell libev about such cases, libev follows |
|
|
1023 | the following policy: Each time C<ev_io_set> is being called, libev |
|
|
1024 | will assume that this is potentially a new file descriptor, otherwise |
|
|
1025 | it is assumed that the file descriptor stays the same. That means that |
|
|
1026 | you I<have> to call C<ev_io_set> (or C<ev_io_init>) when you change the |
|
|
1027 | descriptor even if the file descriptor number itself did not change. |
|
|
1028 | |
|
|
1029 | This is how one would do it normally anyway, the important point is that |
|
|
1030 | the libev application should not optimise around libev but should leave |
|
|
1031 | optimisations to libev. |
|
|
1032 | |
|
|
1033 | =head3 The special problem of dup'ed file descriptors |
|
|
1034 | |
|
|
1035 | Some backends (e.g. epoll), cannot register events for file descriptors, |
|
|
1036 | but only events for the underlying file descriptions. That means when you |
|
|
1037 | have C<dup ()>'ed file descriptors or weirder constellations, and register |
|
|
1038 | events for them, only one file descriptor might actually receive events. |
|
|
1039 | |
|
|
1040 | There is no workaround possible except not registering events |
|
|
1041 | for potentially C<dup ()>'ed file descriptors, or to resort to |
|
|
1042 | C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>. |
|
|
1043 | |
|
|
1044 | =head3 The special problem of fork |
|
|
1045 | |
|
|
1046 | Some backends (epoll, kqueue) do not support C<fork ()> at all or exhibit |
|
|
1047 | useless behaviour. Libev fully supports fork, but needs to be told about |
|
|
1048 | it in the child. |
|
|
1049 | |
|
|
1050 | To support fork in your programs, you either have to call |
|
|
1051 | C<ev_default_fork ()> or C<ev_loop_fork ()> after a fork in the child, |
|
|
1052 | enable C<EVFLAG_FORKCHECK>, or resort to C<EVBACKEND_SELECT> or |
|
|
1053 | C<EVBACKEND_POLL>. |
|
|
1054 | |
|
|
1055 | |
|
|
1056 | =head3 Watcher-Specific Functions |
|
|
1057 | |
913 | =over 4 |
1058 | =over 4 |
914 | |
1059 | |
915 | =item ev_io_init (ev_io *, callback, int fd, int events) |
1060 | =item ev_io_init (ev_io *, callback, int fd, int events) |
916 | |
1061 | |
917 | =item ev_io_set (ev_io *, int fd, int events) |
1062 | =item ev_io_set (ev_io *, int fd, int events) |
… | |
… | |
927 | =item int events [read-only] |
1072 | =item int events [read-only] |
928 | |
1073 | |
929 | The events being watched. |
1074 | The events being watched. |
930 | |
1075 | |
931 | =back |
1076 | =back |
|
|
1077 | |
|
|
1078 | =head3 Examples |
932 | |
1079 | |
933 | Example: Call C<stdin_readable_cb> when STDIN_FILENO has become, well |
1080 | Example: Call C<stdin_readable_cb> when STDIN_FILENO has become, well |
934 | readable, but only once. Since it is likely line-buffered, you could |
1081 | readable, but only once. Since it is likely line-buffered, you could |
935 | attempt to read a whole line in the callback. |
1082 | attempt to read a whole line in the callback. |
936 | |
1083 | |
… | |
… | |
969 | ev_timer_set (&timer, after + ev_now () - ev_time (), 0.); |
1116 | ev_timer_set (&timer, after + ev_now () - ev_time (), 0.); |
970 | |
1117 | |
971 | The callback is guarenteed to be invoked only when its timeout has passed, |
1118 | The callback is guarenteed to be invoked only when its timeout has passed, |
972 | but if multiple timers become ready during the same loop iteration then |
1119 | but if multiple timers become ready during the same loop iteration then |
973 | order of execution is undefined. |
1120 | order of execution is undefined. |
|
|
1121 | |
|
|
1122 | =head3 Watcher-Specific Functions and Data Members |
974 | |
1123 | |
975 | =over 4 |
1124 | =over 4 |
976 | |
1125 | |
977 | =item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat) |
1126 | =item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat) |
978 | |
1127 | |
… | |
… | |
1032 | or C<ev_timer_again> is called and determines the next timeout (if any), |
1181 | or C<ev_timer_again> is called and determines the next timeout (if any), |
1033 | which is also when any modifications are taken into account. |
1182 | which is also when any modifications are taken into account. |
1034 | |
1183 | |
1035 | =back |
1184 | =back |
1036 | |
1185 | |
|
|
1186 | =head3 Examples |
|
|
1187 | |
1037 | Example: Create a timer that fires after 60 seconds. |
1188 | Example: Create a timer that fires after 60 seconds. |
1038 | |
1189 | |
1039 | static void |
1190 | static void |
1040 | one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
1191 | one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
1041 | { |
1192 | { |
… | |
… | |
1084 | |
1235 | |
1085 | As with timers, the callback is guarenteed to be invoked only when the |
1236 | As with timers, the callback is guarenteed to be invoked only when the |
1086 | time (C<at>) has been passed, but if multiple periodic timers become ready |
1237 | time (C<at>) has been passed, but if multiple periodic timers become ready |
1087 | during the same loop iteration then order of execution is undefined. |
1238 | during the same loop iteration then order of execution is undefined. |
1088 | |
1239 | |
|
|
1240 | =head3 Watcher-Specific Functions and Data Members |
|
|
1241 | |
1089 | =over 4 |
1242 | =over 4 |
1090 | |
1243 | |
1091 | =item ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb) |
1244 | =item ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb) |
1092 | |
1245 | |
1093 | =item ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb) |
1246 | =item ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb) |
… | |
… | |
1189 | |
1342 | |
1190 | The current reschedule callback, or C<0>, if this functionality is |
1343 | The current reschedule callback, or C<0>, if this functionality is |
1191 | switched off. Can be changed any time, but changes only take effect when |
1344 | switched off. Can be changed any time, but changes only take effect when |
1192 | the periodic timer fires or C<ev_periodic_again> is being called. |
1345 | the periodic timer fires or C<ev_periodic_again> is being called. |
1193 | |
1346 | |
|
|
1347 | =item ev_tstamp at [read-only] |
|
|
1348 | |
|
|
1349 | When active, contains the absolute time that the watcher is supposed to |
|
|
1350 | trigger next. |
|
|
1351 | |
1194 | =back |
1352 | =back |
|
|
1353 | |
|
|
1354 | =head3 Examples |
1195 | |
1355 | |
1196 | Example: Call a callback every hour, or, more precisely, whenever the |
1356 | Example: Call a callback every hour, or, more precisely, whenever the |
1197 | system clock is divisible by 3600. The callback invocation times have |
1357 | system clock is divisible by 3600. The callback invocation times have |
1198 | potentially a lot of jittering, but good long-term stability. |
1358 | potentially a lot of jittering, but good long-term stability. |
1199 | |
1359 | |
… | |
… | |
1239 | with the kernel (thus it coexists with your own signal handlers as long |
1399 | with the kernel (thus it coexists with your own signal handlers as long |
1240 | as you don't register any with libev). Similarly, when the last signal |
1400 | as you don't register any with libev). Similarly, when the last signal |
1241 | watcher for a signal is stopped libev will reset the signal handler to |
1401 | watcher for a signal is stopped libev will reset the signal handler to |
1242 | SIG_DFL (regardless of what it was set to before). |
1402 | SIG_DFL (regardless of what it was set to before). |
1243 | |
1403 | |
|
|
1404 | =head3 Watcher-Specific Functions and Data Members |
|
|
1405 | |
1244 | =over 4 |
1406 | =over 4 |
1245 | |
1407 | |
1246 | =item ev_signal_init (ev_signal *, callback, int signum) |
1408 | =item ev_signal_init (ev_signal *, callback, int signum) |
1247 | |
1409 | |
1248 | =item ev_signal_set (ev_signal *, int signum) |
1410 | =item ev_signal_set (ev_signal *, int signum) |
… | |
… | |
1259 | |
1421 | |
1260 | =head2 C<ev_child> - watch out for process status changes |
1422 | =head2 C<ev_child> - watch out for process status changes |
1261 | |
1423 | |
1262 | Child watchers trigger when your process receives a SIGCHLD in response to |
1424 | Child watchers trigger when your process receives a SIGCHLD in response to |
1263 | some child status changes (most typically when a child of yours dies). |
1425 | some child status changes (most typically when a child of yours dies). |
|
|
1426 | |
|
|
1427 | =head3 Watcher-Specific Functions and Data Members |
1264 | |
1428 | |
1265 | =over 4 |
1429 | =over 4 |
1266 | |
1430 | |
1267 | =item ev_child_init (ev_child *, callback, int pid) |
1431 | =item ev_child_init (ev_child *, callback, int pid) |
1268 | |
1432 | |
… | |
… | |
1287 | |
1451 | |
1288 | The process exit/trace status caused by C<rpid> (see your systems |
1452 | The process exit/trace status caused by C<rpid> (see your systems |
1289 | C<waitpid> and C<sys/wait.h> documentation for details). |
1453 | C<waitpid> and C<sys/wait.h> documentation for details). |
1290 | |
1454 | |
1291 | =back |
1455 | =back |
|
|
1456 | |
|
|
1457 | =head3 Examples |
1292 | |
1458 | |
1293 | Example: Try to exit cleanly on SIGINT and SIGTERM. |
1459 | Example: Try to exit cleanly on SIGINT and SIGTERM. |
1294 | |
1460 | |
1295 | static void |
1461 | static void |
1296 | sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) |
1462 | sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) |
… | |
… | |
1337 | semantics of C<ev_stat> watchers, which means that libev sometimes needs |
1503 | semantics of C<ev_stat> watchers, which means that libev sometimes needs |
1338 | to fall back to regular polling again even with inotify, but changes are |
1504 | to fall back to regular polling again even with inotify, but changes are |
1339 | usually detected immediately, and if the file exists there will be no |
1505 | usually detected immediately, and if the file exists there will be no |
1340 | polling. |
1506 | polling. |
1341 | |
1507 | |
|
|
1508 | =head3 Inotify |
|
|
1509 | |
|
|
1510 | When C<inotify (7)> support has been compiled into libev (generally only |
|
|
1511 | available on Linux) and present at runtime, it will be used to speed up |
|
|
1512 | change detection where possible. The inotify descriptor will be created lazily |
|
|
1513 | when the first C<ev_stat> watcher is being started. |
|
|
1514 | |
|
|
1515 | Inotify presense does not change the semantics of C<ev_stat> watchers |
|
|
1516 | except that changes might be detected earlier, and in some cases, to avoid |
|
|
1517 | making regular C<stat> calls. Even in the presense of inotify support |
|
|
1518 | there are many cases where libev has to resort to regular C<stat> polling. |
|
|
1519 | |
|
|
1520 | (There is no support for kqueue, as apparently it cannot be used to |
|
|
1521 | implement this functionality, due to the requirement of having a file |
|
|
1522 | descriptor open on the object at all times). |
|
|
1523 | |
|
|
1524 | =head3 The special problem of stat time resolution |
|
|
1525 | |
|
|
1526 | The C<stat ()> syscall only supports full-second resolution portably, and |
|
|
1527 | even on systems where the resolution is higher, many filesystems still |
|
|
1528 | only support whole seconds. |
|
|
1529 | |
|
|
1530 | That means that, if the time is the only thing that changes, you might |
|
|
1531 | miss updates: on the first update, C<ev_stat> detects a change and calls |
|
|
1532 | your callback, which does something. When there is another update within |
|
|
1533 | the same second, C<ev_stat> will be unable to detect it. |
|
|
1534 | |
|
|
1535 | The solution to this is to delay acting on a change for a second (or till |
|
|
1536 | the next second boundary), using a roughly one-second delay C<ev_timer> |
|
|
1537 | (C<ev_timer_set (w, 0., 1.01); ev_timer_again (loop, w)>). The C<.01> |
|
|
1538 | is added to work around small timing inconsistencies of some operating |
|
|
1539 | systems. |
|
|
1540 | |
|
|
1541 | =head3 Watcher-Specific Functions and Data Members |
|
|
1542 | |
1342 | =over 4 |
1543 | =over 4 |
1343 | |
1544 | |
1344 | =item ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval) |
1545 | =item ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval) |
1345 | |
1546 | |
1346 | =item ev_stat_set (ev_stat *, const char *path, ev_tstamp interval) |
1547 | =item ev_stat_set (ev_stat *, const char *path, ev_tstamp interval) |
… | |
… | |
1381 | =item const char *path [read-only] |
1582 | =item const char *path [read-only] |
1382 | |
1583 | |
1383 | The filesystem path that is being watched. |
1584 | The filesystem path that is being watched. |
1384 | |
1585 | |
1385 | =back |
1586 | =back |
|
|
1587 | |
|
|
1588 | =head3 Examples |
1386 | |
1589 | |
1387 | Example: Watch C</etc/passwd> for attribute changes. |
1590 | Example: Watch C</etc/passwd> for attribute changes. |
1388 | |
1591 | |
1389 | static void |
1592 | static void |
1390 | passwd_cb (struct ev_loop *loop, ev_stat *w, int revents) |
1593 | passwd_cb (struct ev_loop *loop, ev_stat *w, int revents) |
… | |
… | |
1403 | } |
1606 | } |
1404 | |
1607 | |
1405 | ... |
1608 | ... |
1406 | ev_stat passwd; |
1609 | ev_stat passwd; |
1407 | |
1610 | |
1408 | ev_stat_init (&passwd, passwd_cb, "/etc/passwd"); |
1611 | ev_stat_init (&passwd, passwd_cb, "/etc/passwd", 0.); |
1409 | ev_stat_start (loop, &passwd); |
1612 | ev_stat_start (loop, &passwd); |
|
|
1613 | |
|
|
1614 | Example: Like above, but additionally use a one-second delay so we do not |
|
|
1615 | miss updates (however, frequent updates will delay processing, too, so |
|
|
1616 | one might do the work both on C<ev_stat> callback invocation I<and> on |
|
|
1617 | C<ev_timer> callback invocation). |
|
|
1618 | |
|
|
1619 | static ev_stat passwd; |
|
|
1620 | static ev_timer timer; |
|
|
1621 | |
|
|
1622 | static void |
|
|
1623 | timer_cb (EV_P_ ev_timer *w, int revents) |
|
|
1624 | { |
|
|
1625 | ev_timer_stop (EV_A_ w); |
|
|
1626 | |
|
|
1627 | /* now it's one second after the most recent passwd change */ |
|
|
1628 | } |
|
|
1629 | |
|
|
1630 | static void |
|
|
1631 | stat_cb (EV_P_ ev_stat *w, int revents) |
|
|
1632 | { |
|
|
1633 | /* reset the one-second timer */ |
|
|
1634 | ev_timer_again (EV_A_ &timer); |
|
|
1635 | } |
|
|
1636 | |
|
|
1637 | ... |
|
|
1638 | ev_stat_init (&passwd, stat_cb, "/etc/passwd", 0.); |
|
|
1639 | ev_stat_start (loop, &passwd); |
|
|
1640 | ev_timer_init (&timer, timer_cb, 0., 1.01); |
1410 | |
1641 | |
1411 | |
1642 | |
1412 | =head2 C<ev_idle> - when you've got nothing better to do... |
1643 | =head2 C<ev_idle> - when you've got nothing better to do... |
1413 | |
1644 | |
1414 | Idle watchers trigger events when no other events of the same or higher |
1645 | Idle watchers trigger events when no other events of the same or higher |
… | |
… | |
1428 | Apart from keeping your process non-blocking (which is a useful |
1659 | Apart from keeping your process non-blocking (which is a useful |
1429 | effect on its own sometimes), idle watchers are a good place to do |
1660 | effect on its own sometimes), idle watchers are a good place to do |
1430 | "pseudo-background processing", or delay processing stuff to after the |
1661 | "pseudo-background processing", or delay processing stuff to after the |
1431 | event loop has handled all outstanding events. |
1662 | event loop has handled all outstanding events. |
1432 | |
1663 | |
|
|
1664 | =head3 Watcher-Specific Functions and Data Members |
|
|
1665 | |
1433 | =over 4 |
1666 | =over 4 |
1434 | |
1667 | |
1435 | =item ev_idle_init (ev_signal *, callback) |
1668 | =item ev_idle_init (ev_signal *, callback) |
1436 | |
1669 | |
1437 | Initialises and configures the idle watcher - it has no parameters of any |
1670 | Initialises and configures the idle watcher - it has no parameters of any |
1438 | kind. There is a C<ev_idle_set> macro, but using it is utterly pointless, |
1671 | kind. There is a C<ev_idle_set> macro, but using it is utterly pointless, |
1439 | believe me. |
1672 | believe me. |
1440 | |
1673 | |
1441 | =back |
1674 | =back |
|
|
1675 | |
|
|
1676 | =head3 Examples |
1442 | |
1677 | |
1443 | Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the |
1678 | Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the |
1444 | callback, free it. Also, use no error checking, as usual. |
1679 | callback, free it. Also, use no error checking, as usual. |
1445 | |
1680 | |
1446 | static void |
1681 | static void |
… | |
… | |
1498 | |
1733 | |
1499 | It is recommended to give C<ev_check> watchers highest (C<EV_MAXPRI>) |
1734 | It is recommended to give C<ev_check> watchers highest (C<EV_MAXPRI>) |
1500 | priority, to ensure that they are being run before any other watchers |
1735 | priority, to ensure that they are being run before any other watchers |
1501 | after the poll. Also, C<ev_check> watchers (and C<ev_prepare> watchers, |
1736 | after the poll. Also, C<ev_check> watchers (and C<ev_prepare> watchers, |
1502 | too) should not activate ("feed") events into libev. While libev fully |
1737 | too) should not activate ("feed") events into libev. While libev fully |
1503 | supports this, they will be called before other C<ev_check> watchers did |
1738 | supports this, they will be called before other C<ev_check> watchers |
1504 | their job. As C<ev_check> watchers are often used to embed other event |
1739 | did their job. As C<ev_check> watchers are often used to embed other |
1505 | loops those other event loops might be in an unusable state until their |
1740 | (non-libev) event loops those other event loops might be in an unusable |
1506 | C<ev_check> watcher ran (always remind yourself to coexist peacefully with |
1741 | state until their C<ev_check> watcher ran (always remind yourself to |
1507 | others). |
1742 | coexist peacefully with others). |
|
|
1743 | |
|
|
1744 | =head3 Watcher-Specific Functions and Data Members |
1508 | |
1745 | |
1509 | =over 4 |
1746 | =over 4 |
1510 | |
1747 | |
1511 | =item ev_prepare_init (ev_prepare *, callback) |
1748 | =item ev_prepare_init (ev_prepare *, callback) |
1512 | |
1749 | |
… | |
… | |
1515 | Initialises and configures the prepare or check watcher - they have no |
1752 | Initialises and configures the prepare or check watcher - they have no |
1516 | parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set> |
1753 | parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set> |
1517 | macros, but using them is utterly, utterly and completely pointless. |
1754 | macros, but using them is utterly, utterly and completely pointless. |
1518 | |
1755 | |
1519 | =back |
1756 | =back |
|
|
1757 | |
|
|
1758 | =head3 Examples |
1520 | |
1759 | |
1521 | There are a number of principal ways to embed other event loops or modules |
1760 | There are a number of principal ways to embed other event loops or modules |
1522 | into libev. Here are some ideas on how to include libadns into libev |
1761 | into libev. Here are some ideas on how to include libadns into libev |
1523 | (there is a Perl module named C<EV::ADNS> that does this, which you could |
1762 | (there is a Perl module named C<EV::ADNS> that does this, which you could |
1524 | use for an actually working example. Another Perl module named C<EV::Glib> |
1763 | use for an actually working example. Another Perl module named C<EV::Glib> |
… | |
… | |
1693 | portable one. |
1932 | portable one. |
1694 | |
1933 | |
1695 | So when you want to use this feature you will always have to be prepared |
1934 | So when you want to use this feature you will always have to be prepared |
1696 | that you cannot get an embeddable loop. The recommended way to get around |
1935 | that you cannot get an embeddable loop. The recommended way to get around |
1697 | this is to have a separate variables for your embeddable loop, try to |
1936 | this is to have a separate variables for your embeddable loop, try to |
1698 | create it, and if that fails, use the normal loop for everything: |
1937 | create it, and if that fails, use the normal loop for everything. |
|
|
1938 | |
|
|
1939 | =head3 Watcher-Specific Functions and Data Members |
|
|
1940 | |
|
|
1941 | =over 4 |
|
|
1942 | |
|
|
1943 | =item ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop) |
|
|
1944 | |
|
|
1945 | =item ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop) |
|
|
1946 | |
|
|
1947 | Configures the watcher to embed the given loop, which must be |
|
|
1948 | embeddable. If the callback is C<0>, then C<ev_embed_sweep> will be |
|
|
1949 | invoked automatically, otherwise it is the responsibility of the callback |
|
|
1950 | to invoke it (it will continue to be called until the sweep has been done, |
|
|
1951 | if you do not want thta, you need to temporarily stop the embed watcher). |
|
|
1952 | |
|
|
1953 | =item ev_embed_sweep (loop, ev_embed *) |
|
|
1954 | |
|
|
1955 | Make a single, non-blocking sweep over the embedded loop. This works |
|
|
1956 | similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most |
|
|
1957 | apropriate way for embedded loops. |
|
|
1958 | |
|
|
1959 | =item struct ev_loop *other [read-only] |
|
|
1960 | |
|
|
1961 | The embedded event loop. |
|
|
1962 | |
|
|
1963 | =back |
|
|
1964 | |
|
|
1965 | =head3 Examples |
|
|
1966 | |
|
|
1967 | Example: Try to get an embeddable event loop and embed it into the default |
|
|
1968 | event loop. If that is not possible, use the default loop. The default |
|
|
1969 | loop is stored in C<loop_hi>, while the mebeddable loop is stored in |
|
|
1970 | C<loop_lo> (which is C<loop_hi> in the acse no embeddable loop can be |
|
|
1971 | used). |
1699 | |
1972 | |
1700 | struct ev_loop *loop_hi = ev_default_init (0); |
1973 | struct ev_loop *loop_hi = ev_default_init (0); |
1701 | struct ev_loop *loop_lo = 0; |
1974 | struct ev_loop *loop_lo = 0; |
1702 | struct ev_embed embed; |
1975 | struct ev_embed embed; |
1703 | |
1976 | |
… | |
… | |
1714 | ev_embed_start (loop_hi, &embed); |
1987 | ev_embed_start (loop_hi, &embed); |
1715 | } |
1988 | } |
1716 | else |
1989 | else |
1717 | loop_lo = loop_hi; |
1990 | loop_lo = loop_hi; |
1718 | |
1991 | |
1719 | =over 4 |
1992 | Example: Check if kqueue is available but not recommended and create |
|
|
1993 | a kqueue backend for use with sockets (which usually work with any |
|
|
1994 | kqueue implementation). Store the kqueue/socket-only event loop in |
|
|
1995 | C<loop_socket>. (One might optionally use C<EVFLAG_NOENV>, too). |
1720 | |
1996 | |
1721 | =item ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop) |
1997 | struct ev_loop *loop = ev_default_init (0); |
|
|
1998 | struct ev_loop *loop_socket = 0; |
|
|
1999 | struct ev_embed embed; |
|
|
2000 | |
|
|
2001 | if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE) |
|
|
2002 | if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE)) |
|
|
2003 | { |
|
|
2004 | ev_embed_init (&embed, 0, loop_socket); |
|
|
2005 | ev_embed_start (loop, &embed); |
|
|
2006 | } |
1722 | |
2007 | |
1723 | =item ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop) |
2008 | if (!loop_socket) |
|
|
2009 | loop_socket = loop; |
1724 | |
2010 | |
1725 | Configures the watcher to embed the given loop, which must be |
2011 | // now use loop_socket for all sockets, and loop for everything else |
1726 | embeddable. If the callback is C<0>, then C<ev_embed_sweep> will be |
|
|
1727 | invoked automatically, otherwise it is the responsibility of the callback |
|
|
1728 | to invoke it (it will continue to be called until the sweep has been done, |
|
|
1729 | if you do not want thta, you need to temporarily stop the embed watcher). |
|
|
1730 | |
|
|
1731 | =item ev_embed_sweep (loop, ev_embed *) |
|
|
1732 | |
|
|
1733 | Make a single, non-blocking sweep over the embedded loop. This works |
|
|
1734 | similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most |
|
|
1735 | apropriate way for embedded loops. |
|
|
1736 | |
|
|
1737 | =item struct ev_loop *loop [read-only] |
|
|
1738 | |
|
|
1739 | The embedded event loop. |
|
|
1740 | |
|
|
1741 | =back |
|
|
1742 | |
2012 | |
1743 | |
2013 | |
1744 | =head2 C<ev_fork> - the audacity to resume the event loop after a fork |
2014 | =head2 C<ev_fork> - the audacity to resume the event loop after a fork |
1745 | |
2015 | |
1746 | Fork watchers are called when a C<fork ()> was detected (usually because |
2016 | Fork watchers are called when a C<fork ()> was detected (usually because |
… | |
… | |
1749 | event loop blocks next and before C<ev_check> watchers are being called, |
2019 | event loop blocks next and before C<ev_check> watchers are being called, |
1750 | and only in the child after the fork. If whoever good citizen calling |
2020 | and only in the child after the fork. If whoever good citizen calling |
1751 | C<ev_default_fork> cheats and calls it in the wrong process, the fork |
2021 | C<ev_default_fork> cheats and calls it in the wrong process, the fork |
1752 | handlers will be invoked, too, of course. |
2022 | handlers will be invoked, too, of course. |
1753 | |
2023 | |
|
|
2024 | =head3 Watcher-Specific Functions and Data Members |
|
|
2025 | |
1754 | =over 4 |
2026 | =over 4 |
1755 | |
2027 | |
1756 | =item ev_fork_init (ev_signal *, callback) |
2028 | =item ev_fork_init (ev_signal *, callback) |
1757 | |
2029 | |
1758 | Initialises and configures the fork watcher - it has no parameters of any |
2030 | Initialises and configures the fork watcher - it has no parameters of any |
… | |
… | |
1974 | |
2246 | |
1975 | =item w->stop () |
2247 | =item w->stop () |
1976 | |
2248 | |
1977 | Stops the watcher if it is active. Again, no C<loop> argument. |
2249 | Stops the watcher if it is active. Again, no C<loop> argument. |
1978 | |
2250 | |
1979 | =item w->again () C<ev::timer>, C<ev::periodic> only |
2251 | =item w->again () (C<ev::timer>, C<ev::periodic> only) |
1980 | |
2252 | |
1981 | For C<ev::timer> and C<ev::periodic>, this invokes the corresponding |
2253 | For C<ev::timer> and C<ev::periodic>, this invokes the corresponding |
1982 | C<ev_TYPE_again> function. |
2254 | C<ev_TYPE_again> function. |
1983 | |
2255 | |
1984 | =item w->sweep () C<ev::embed> only |
2256 | =item w->sweep () (C<ev::embed> only) |
1985 | |
2257 | |
1986 | Invokes C<ev_embed_sweep>. |
2258 | Invokes C<ev_embed_sweep>. |
1987 | |
2259 | |
1988 | =item w->update () C<ev::stat> only |
2260 | =item w->update () (C<ev::stat> only) |
1989 | |
2261 | |
1990 | Invokes C<ev_stat_stat>. |
2262 | Invokes C<ev_stat_stat>. |
1991 | |
2263 | |
1992 | =back |
2264 | =back |
1993 | |
2265 | |
… | |
… | |
2013 | } |
2285 | } |
2014 | |
2286 | |
2015 | |
2287 | |
2016 | =head1 MACRO MAGIC |
2288 | =head1 MACRO MAGIC |
2017 | |
2289 | |
2018 | Libev can be compiled with a variety of options, the most fundemantal is |
2290 | Libev can be compiled with a variety of options, the most fundamantal |
2019 | C<EV_MULTIPLICITY>. This option determines whether (most) functions and |
2291 | of which is C<EV_MULTIPLICITY>. This option determines whether (most) |
2020 | callbacks have an initial C<struct ev_loop *> argument. |
2292 | functions and callbacks have an initial C<struct ev_loop *> argument. |
2021 | |
2293 | |
2022 | To make it easier to write programs that cope with either variant, the |
2294 | To make it easier to write programs that cope with either variant, the |
2023 | following macros are defined: |
2295 | following macros are defined: |
2024 | |
2296 | |
2025 | =over 4 |
2297 | =over 4 |
… | |
… | |
2079 | Libev can (and often is) directly embedded into host |
2351 | Libev can (and often is) directly embedded into host |
2080 | applications. Examples of applications that embed it include the Deliantra |
2352 | applications. Examples of applications that embed it include the Deliantra |
2081 | Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe) |
2353 | Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe) |
2082 | and rxvt-unicode. |
2354 | and rxvt-unicode. |
2083 | |
2355 | |
2084 | The goal is to enable you to just copy the neecssary files into your |
2356 | The goal is to enable you to just copy the necessary files into your |
2085 | source directory without having to change even a single line in them, so |
2357 | source directory without having to change even a single line in them, so |
2086 | you can easily upgrade by simply copying (or having a checked-out copy of |
2358 | you can easily upgrade by simply copying (or having a checked-out copy of |
2087 | libev somewhere in your source tree). |
2359 | libev somewhere in your source tree). |
2088 | |
2360 | |
2089 | =head2 FILESETS |
2361 | =head2 FILESETS |
… | |
… | |
2179 | |
2451 | |
2180 | If defined to be C<1>, libev will try to detect the availability of the |
2452 | If defined to be C<1>, libev will try to detect the availability of the |
2181 | monotonic clock option at both compiletime and runtime. Otherwise no use |
2453 | monotonic clock option at both compiletime and runtime. Otherwise no use |
2182 | of the monotonic clock option will be attempted. If you enable this, you |
2454 | of the monotonic clock option will be attempted. If you enable this, you |
2183 | usually have to link against librt or something similar. Enabling it when |
2455 | usually have to link against librt or something similar. Enabling it when |
2184 | the functionality isn't available is safe, though, althoguh you have |
2456 | the functionality isn't available is safe, though, although you have |
2185 | to make sure you link against any libraries where the C<clock_gettime> |
2457 | to make sure you link against any libraries where the C<clock_gettime> |
2186 | function is hiding in (often F<-lrt>). |
2458 | function is hiding in (often F<-lrt>). |
2187 | |
2459 | |
2188 | =item EV_USE_REALTIME |
2460 | =item EV_USE_REALTIME |
2189 | |
2461 | |
2190 | If defined to be C<1>, libev will try to detect the availability of the |
2462 | If defined to be C<1>, libev will try to detect the availability of the |
2191 | realtime clock option at compiletime (and assume its availability at |
2463 | realtime clock option at compiletime (and assume its availability at |
2192 | runtime if successful). Otherwise no use of the realtime clock option will |
2464 | runtime if successful). Otherwise no use of the realtime clock option will |
2193 | be attempted. This effectively replaces C<gettimeofday> by C<clock_get |
2465 | be attempted. This effectively replaces C<gettimeofday> by C<clock_get |
2194 | (CLOCK_REALTIME, ...)> and will not normally affect correctness. See tzhe note about libraries |
2466 | (CLOCK_REALTIME, ...)> and will not normally affect correctness. See the |
2195 | in the description of C<EV_USE_MONOTONIC>, though. |
2467 | note about libraries in the description of C<EV_USE_MONOTONIC>, though. |
|
|
2468 | |
|
|
2469 | =item EV_USE_NANOSLEEP |
|
|
2470 | |
|
|
2471 | If defined to be C<1>, libev will assume that C<nanosleep ()> is available |
|
|
2472 | and will use it for delays. Otherwise it will use C<select ()>. |
2196 | |
2473 | |
2197 | =item EV_USE_SELECT |
2474 | =item EV_USE_SELECT |
2198 | |
2475 | |
2199 | If undefined or defined to be C<1>, libev will compile in support for the |
2476 | If undefined or defined to be C<1>, libev will compile in support for the |
2200 | C<select>(2) backend. No attempt at autodetection will be done: if no |
2477 | C<select>(2) backend. No attempt at autodetection will be done: if no |
… | |
… | |
2218 | wants osf handles on win32 (this is the case when the select to |
2495 | wants osf handles on win32 (this is the case when the select to |
2219 | be used is the winsock select). This means that it will call |
2496 | be used is the winsock select). This means that it will call |
2220 | C<_get_osfhandle> on the fd to convert it to an OS handle. Otherwise, |
2497 | C<_get_osfhandle> on the fd to convert it to an OS handle. Otherwise, |
2221 | it is assumed that all these functions actually work on fds, even |
2498 | it is assumed that all these functions actually work on fds, even |
2222 | on win32. Should not be defined on non-win32 platforms. |
2499 | on win32. Should not be defined on non-win32 platforms. |
|
|
2500 | |
|
|
2501 | =item EV_FD_TO_WIN32_HANDLE |
|
|
2502 | |
|
|
2503 | If C<EV_SELECT_IS_WINSOCKET> is enabled, then libev needs a way to map |
|
|
2504 | file descriptors to socket handles. When not defining this symbol (the |
|
|
2505 | default), then libev will call C<_get_osfhandle>, which is usually |
|
|
2506 | correct. In some cases, programs use their own file descriptor management, |
|
|
2507 | in which case they can provide this function to map fds to socket handles. |
2223 | |
2508 | |
2224 | =item EV_USE_POLL |
2509 | =item EV_USE_POLL |
2225 | |
2510 | |
2226 | If defined to be C<1>, libev will compile in support for the C<poll>(2) |
2511 | If defined to be C<1>, libev will compile in support for the C<poll>(2) |
2227 | backend. Otherwise it will be enabled on non-win32 platforms. It |
2512 | backend. Otherwise it will be enabled on non-win32 platforms. It |
… | |
… | |
2264 | be detected at runtime. |
2549 | be detected at runtime. |
2265 | |
2550 | |
2266 | =item EV_H |
2551 | =item EV_H |
2267 | |
2552 | |
2268 | The name of the F<ev.h> header file used to include it. The default if |
2553 | The name of the F<ev.h> header file used to include it. The default if |
2269 | undefined is C<< <ev.h> >> in F<event.h> and C<"ev.h"> in F<ev.c>. This |
2554 | undefined is C<"ev.h"> in F<event.h> and F<ev.c>. This can be used to |
2270 | can be used to virtually rename the F<ev.h> header file in case of conflicts. |
2555 | virtually rename the F<ev.h> header file in case of conflicts. |
2271 | |
2556 | |
2272 | =item EV_CONFIG_H |
2557 | =item EV_CONFIG_H |
2273 | |
2558 | |
2274 | If C<EV_STANDALONE> isn't C<1>, this variable can be used to override |
2559 | If C<EV_STANDALONE> isn't C<1>, this variable can be used to override |
2275 | F<ev.c>'s idea of where to find the F<config.h> file, similarly to |
2560 | F<ev.c>'s idea of where to find the F<config.h> file, similarly to |
2276 | C<EV_H>, above. |
2561 | C<EV_H>, above. |
2277 | |
2562 | |
2278 | =item EV_EVENT_H |
2563 | =item EV_EVENT_H |
2279 | |
2564 | |
2280 | Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea |
2565 | Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea |
2281 | of how the F<event.h> header can be found. |
2566 | of how the F<event.h> header can be found, the dfeault is C<"event.h">. |
2282 | |
2567 | |
2283 | =item EV_PROTOTYPES |
2568 | =item EV_PROTOTYPES |
2284 | |
2569 | |
2285 | If defined to be C<0>, then F<ev.h> will not define any function |
2570 | If defined to be C<0>, then F<ev.h> will not define any function |
2286 | prototypes, but still define all the structs and other symbols. This is |
2571 | prototypes, but still define all the structs and other symbols. This is |
… | |
… | |
2352 | than enough. If you need to manage thousands of children you might want to |
2637 | than enough. If you need to manage thousands of children you might want to |
2353 | increase this value (I<must> be a power of two). |
2638 | increase this value (I<must> be a power of two). |
2354 | |
2639 | |
2355 | =item EV_INOTIFY_HASHSIZE |
2640 | =item EV_INOTIFY_HASHSIZE |
2356 | |
2641 | |
2357 | C<ev_staz> watchers use a small hash table to distribute workload by |
2642 | C<ev_stat> watchers use a small hash table to distribute workload by |
2358 | inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>), |
2643 | inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>), |
2359 | usually more than enough. If you need to manage thousands of C<ev_stat> |
2644 | usually more than enough. If you need to manage thousands of C<ev_stat> |
2360 | watchers you might want to increase this value (I<must> be a power of |
2645 | watchers you might want to increase this value (I<must> be a power of |
2361 | two). |
2646 | two). |
2362 | |
2647 | |
… | |
… | |
2379 | |
2664 | |
2380 | =item ev_set_cb (ev, cb) |
2665 | =item ev_set_cb (ev, cb) |
2381 | |
2666 | |
2382 | Can be used to change the callback member declaration in each watcher, |
2667 | Can be used to change the callback member declaration in each watcher, |
2383 | and the way callbacks are invoked and set. Must expand to a struct member |
2668 | and the way callbacks are invoked and set. Must expand to a struct member |
2384 | definition and a statement, respectively. See the F<ev.v> header file for |
2669 | definition and a statement, respectively. See the F<ev.h> header file for |
2385 | their default definitions. One possible use for overriding these is to |
2670 | their default definitions. One possible use for overriding these is to |
2386 | avoid the C<struct ev_loop *> as first argument in all cases, or to use |
2671 | avoid the C<struct ev_loop *> as first argument in all cases, or to use |
2387 | method calls instead of plain function calls in C++. |
2672 | method calls instead of plain function calls in C++. |
|
|
2673 | |
|
|
2674 | =head2 EXPORTED API SYMBOLS |
|
|
2675 | |
|
|
2676 | If you need to re-export the API (e.g. via a dll) and you need a list of |
|
|
2677 | exported symbols, you can use the provided F<Symbol.*> files which list |
|
|
2678 | all public symbols, one per line: |
|
|
2679 | |
|
|
2680 | Symbols.ev for libev proper |
|
|
2681 | Symbols.event for the libevent emulation |
|
|
2682 | |
|
|
2683 | This can also be used to rename all public symbols to avoid clashes with |
|
|
2684 | multiple versions of libev linked together (which is obviously bad in |
|
|
2685 | itself, but sometimes it is inconvinient to avoid this). |
|
|
2686 | |
|
|
2687 | A sed command like this will create wrapper C<#define>'s that you need to |
|
|
2688 | include before including F<ev.h>: |
|
|
2689 | |
|
|
2690 | <Symbols.ev sed -e "s/.*/#define & myprefix_&/" >wrap.h |
|
|
2691 | |
|
|
2692 | This would create a file F<wrap.h> which essentially looks like this: |
|
|
2693 | |
|
|
2694 | #define ev_backend myprefix_ev_backend |
|
|
2695 | #define ev_check_start myprefix_ev_check_start |
|
|
2696 | #define ev_check_stop myprefix_ev_check_stop |
|
|
2697 | ... |
2388 | |
2698 | |
2389 | =head2 EXAMPLES |
2699 | =head2 EXAMPLES |
2390 | |
2700 | |
2391 | For a real-world example of a program the includes libev |
2701 | For a real-world example of a program the includes libev |
2392 | verbatim, you can have a look at the EV perl module |
2702 | verbatim, you can have a look at the EV perl module |
… | |
… | |
2433 | |
2743 | |
2434 | =item Starting and stopping timer/periodic watchers: O(log skipped_other_timers) |
2744 | =item Starting and stopping timer/periodic watchers: O(log skipped_other_timers) |
2435 | |
2745 | |
2436 | This means that, when you have a watcher that triggers in one hour and |
2746 | This means that, when you have a watcher that triggers in one hour and |
2437 | there are 100 watchers that would trigger before that then inserting will |
2747 | there are 100 watchers that would trigger before that then inserting will |
2438 | have to skip those 100 watchers. |
2748 | have to skip roughly seven (C<ld 100>) of these watchers. |
2439 | |
2749 | |
2440 | =item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers) |
2750 | =item Changing timer/periodic watchers (by autorepeat or calling again): O(log skipped_other_timers) |
2441 | |
2751 | |
2442 | That means that for changing a timer costs less than removing/adding them |
2752 | That means that changing a timer costs less than removing/adding them |
2443 | as only the relative motion in the event queue has to be paid for. |
2753 | as only the relative motion in the event queue has to be paid for. |
2444 | |
2754 | |
2445 | =item Starting io/check/prepare/idle/signal/child watchers: O(1) |
2755 | =item Starting io/check/prepare/idle/signal/child watchers: O(1) |
2446 | |
2756 | |
2447 | These just add the watcher into an array or at the head of a list. |
2757 | These just add the watcher into an array or at the head of a list. |
|
|
2758 | |
2448 | =item Stopping check/prepare/idle watchers: O(1) |
2759 | =item Stopping check/prepare/idle watchers: O(1) |
2449 | |
2760 | |
2450 | =item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE)) |
2761 | =item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE)) |
2451 | |
2762 | |
2452 | These watchers are stored in lists then need to be walked to find the |
2763 | These watchers are stored in lists then need to be walked to find the |
2453 | correct watcher to remove. The lists are usually short (you don't usually |
2764 | correct watcher to remove. The lists are usually short (you don't usually |
2454 | have many watchers waiting for the same fd or signal). |
2765 | have many watchers waiting for the same fd or signal). |
2455 | |
2766 | |
2456 | =item Finding the next timer per loop iteration: O(1) |
2767 | =item Finding the next timer in each loop iteration: O(1) |
|
|
2768 | |
|
|
2769 | By virtue of using a binary heap, the next timer is always found at the |
|
|
2770 | beginning of the storage array. |
2457 | |
2771 | |
2458 | =item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd) |
2772 | =item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd) |
2459 | |
2773 | |
2460 | A change means an I/O watcher gets started or stopped, which requires |
2774 | A change means an I/O watcher gets started or stopped, which requires |
2461 | libev to recalculate its status (and possibly tell the kernel). |
2775 | libev to recalculate its status (and possibly tell the kernel, depending |
|
|
2776 | on backend and wether C<ev_io_set> was used). |
2462 | |
2777 | |
2463 | =item Activating one watcher: O(1) |
2778 | =item Activating one watcher (putting it into the pending state): O(1) |
2464 | |
2779 | |
2465 | =item Priority handling: O(number_of_priorities) |
2780 | =item Priority handling: O(number_of_priorities) |
2466 | |
2781 | |
2467 | Priorities are implemented by allocating some space for each |
2782 | Priorities are implemented by allocating some space for each |
2468 | priority. When doing priority-based operations, libev usually has to |
2783 | priority. When doing priority-based operations, libev usually has to |
2469 | linearly search all the priorities. |
2784 | linearly search all the priorities, but starting/stopping and activating |
|
|
2785 | watchers becomes O(1) w.r.t. prioritiy handling. |
2470 | |
2786 | |
2471 | =back |
2787 | =back |
2472 | |
2788 | |
2473 | |
2789 | |
|
|
2790 | =head1 Win32 platform limitations and workarounds |
|
|
2791 | |
|
|
2792 | Win32 doesn't support any of the standards (e.g. POSIX) that libev |
|
|
2793 | requires, and its I/O model is fundamentally incompatible with the POSIX |
|
|
2794 | model. Libev still offers limited functionality on this platform in |
|
|
2795 | the form of the C<EVBACKEND_SELECT> backend, and only supports socket |
|
|
2796 | descriptors. This only applies when using Win32 natively, not when using |
|
|
2797 | e.g. cygwin. |
|
|
2798 | |
|
|
2799 | There is no supported compilation method available on windows except |
|
|
2800 | embedding it into other applications. |
|
|
2801 | |
|
|
2802 | Due to the many, low, and arbitrary limits on the win32 platform and the |
|
|
2803 | abysmal performance of winsockets, using a large number of sockets is not |
|
|
2804 | recommended (and not reasonable). If your program needs to use more than |
|
|
2805 | a hundred or so sockets, then likely it needs to use a totally different |
|
|
2806 | implementation for windows, as libev offers the POSIX model, which cannot |
|
|
2807 | be implemented efficiently on windows (microsoft monopoly games). |
|
|
2808 | |
|
|
2809 | =over 4 |
|
|
2810 | |
|
|
2811 | =item The winsocket select function |
|
|
2812 | |
|
|
2813 | The winsocket C<select> function doesn't follow POSIX in that it requires |
|
|
2814 | socket I<handles> and not socket I<file descriptors>. This makes select |
|
|
2815 | very inefficient, and also requires a mapping from file descriptors |
|
|
2816 | to socket handles. See the discussion of the C<EV_SELECT_USE_FD_SET>, |
|
|
2817 | C<EV_SELECT_IS_WINSOCKET> and C<EV_FD_TO_WIN32_HANDLE> preprocessor |
|
|
2818 | symbols for more info. |
|
|
2819 | |
|
|
2820 | The configuration for a "naked" win32 using the microsoft runtime |
|
|
2821 | libraries and raw winsocket select is: |
|
|
2822 | |
|
|
2823 | #define EV_USE_SELECT 1 |
|
|
2824 | #define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */ |
|
|
2825 | |
|
|
2826 | Note that winsockets handling of fd sets is O(n), so you can easily get a |
|
|
2827 | complexity in the O(n²) range when using win32. |
|
|
2828 | |
|
|
2829 | =item Limited number of file descriptors |
|
|
2830 | |
|
|
2831 | Windows has numerous arbitrary (and low) limits on things. Early versions |
|
|
2832 | of winsocket's select only supported waiting for a max. of C<64> handles |
|
|
2833 | (probably owning to the fact that all windows kernels can only wait for |
|
|
2834 | C<64> things at the same time internally; microsoft recommends spawning a |
|
|
2835 | chain of threads and wait for 63 handles and the previous thread in each). |
|
|
2836 | |
|
|
2837 | Newer versions support more handles, but you need to define C<FD_SETSIZE> |
|
|
2838 | to some high number (e.g. C<2048>) before compiling the winsocket select |
|
|
2839 | call (which might be in libev or elsewhere, for example, perl does its own |
|
|
2840 | select emulation on windows). |
|
|
2841 | |
|
|
2842 | Another limit is the number of file descriptors in the microsoft runtime |
|
|
2843 | libraries, which by default is C<64> (there must be a hidden I<64> fetish |
|
|
2844 | or something like this inside microsoft). You can increase this by calling |
|
|
2845 | C<_setmaxstdio>, which can increase this limit to C<2048> (another |
|
|
2846 | arbitrary limit), but is broken in many versions of the microsoft runtime |
|
|
2847 | libraries. |
|
|
2848 | |
|
|
2849 | This might get you to about C<512> or C<2048> sockets (depending on |
|
|
2850 | windows version and/or the phase of the moon). To get more, you need to |
|
|
2851 | wrap all I/O functions and provide your own fd management, but the cost of |
|
|
2852 | calling select (O(n²)) will likely make this unworkable. |
|
|
2853 | |
|
|
2854 | =back |
|
|
2855 | |
|
|
2856 | |
2474 | =head1 AUTHOR |
2857 | =head1 AUTHOR |
2475 | |
2858 | |
2476 | Marc Lehmann <libev@schmorp.de>. |
2859 | Marc Lehmann <libev@schmorp.de>. |
2477 | |
2860 | |