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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 | |
… | |
… | |
736 | =item bool ev_is_pending (ev_TYPE *watcher) |
837 | =item bool ev_is_pending (ev_TYPE *watcher) |
737 | |
838 | |
738 | Returns a true value iff the watcher is pending, (i.e. it has outstanding |
839 | Returns a true value iff the watcher is pending, (i.e. it has outstanding |
739 | events but its callback has not yet been invoked). As long as a watcher |
840 | events but its callback has not yet been invoked). As long as a watcher |
740 | is pending (but not active) you must not call an init function on it (but |
841 | is pending (but not active) you must not call an init function on it (but |
741 | C<ev_TYPE_set> is safe) and you must make sure the watcher is available to |
842 | C<ev_TYPE_set> is safe), you must not change its priority, and you must |
742 | libev (e.g. you cnanot C<free ()> it). |
843 | make sure the watcher is available to libev (e.g. you cannot C<free ()> |
|
|
844 | it). |
743 | |
845 | |
744 | =item callback ev_cb (ev_TYPE *watcher) |
846 | =item callback ev_cb (ev_TYPE *watcher) |
745 | |
847 | |
746 | Returns the callback currently set on the watcher. |
848 | Returns the callback currently set on the watcher. |
747 | |
849 | |
… | |
… | |
766 | watchers on the same event and make sure one is called first. |
868 | watchers on the same event and make sure one is called first. |
767 | |
869 | |
768 | If you need to suppress invocation when higher priority events are pending |
870 | If you need to suppress invocation when higher priority events are pending |
769 | you need to look at C<ev_idle> watchers, which provide this functionality. |
871 | you need to look at C<ev_idle> watchers, which provide this functionality. |
770 | |
872 | |
|
|
873 | You I<must not> change the priority of a watcher as long as it is active or |
|
|
874 | pending. |
|
|
875 | |
771 | The default priority used by watchers when no priority has been set is |
876 | The default priority used by watchers when no priority has been set is |
772 | always C<0>, which is supposed to not be too high and not be too low :). |
877 | always C<0>, which is supposed to not be too high and not be too low :). |
773 | |
878 | |
774 | Setting a priority outside the range of C<EV_MINPRI> to C<EV_MAXPRI> is |
879 | Setting a priority outside the range of C<EV_MINPRI> to C<EV_MAXPRI> is |
775 | fine, as long as you do not mind that the priority value you query might |
880 | fine, as long as you do not mind that the priority value you query might |
776 | or might not have been adjusted to be within valid range. |
881 | or might not have been adjusted to be within valid range. |
|
|
882 | |
|
|
883 | =item ev_invoke (loop, ev_TYPE *watcher, int revents) |
|
|
884 | |
|
|
885 | Invoke the C<watcher> with the given C<loop> and C<revents>. Neither |
|
|
886 | C<loop> nor C<revents> need to be valid as long as the watcher callback |
|
|
887 | can deal with that fact. |
|
|
888 | |
|
|
889 | =item int ev_clear_pending (loop, ev_TYPE *watcher) |
|
|
890 | |
|
|
891 | If the watcher is pending, this function returns clears its pending status |
|
|
892 | and returns its C<revents> bitset (as if its callback was invoked). If the |
|
|
893 | watcher isn't pending it does nothing and returns C<0>. |
777 | |
894 | |
778 | =back |
895 | =back |
779 | |
896 | |
780 | |
897 | |
781 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
898 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
… | |
… | |
891 | 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 |
892 | 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 |
893 | 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 |
894 | its own, so its quite safe to use). |
1011 | its own, so its quite safe to use). |
895 | |
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 | |
896 | =over 4 |
1059 | =over 4 |
897 | |
1060 | |
898 | =item ev_io_init (ev_io *, callback, int fd, int events) |
1061 | =item ev_io_init (ev_io *, callback, int fd, int events) |
899 | |
1062 | |
900 | =item ev_io_set (ev_io *, int fd, int events) |
1063 | =item ev_io_set (ev_io *, int fd, int events) |
… | |
… | |
952 | ev_timer_set (&timer, after + ev_now () - ev_time (), 0.); |
1115 | ev_timer_set (&timer, after + ev_now () - ev_time (), 0.); |
953 | |
1116 | |
954 | 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, |
955 | 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 |
956 | order of execution is undefined. |
1119 | order of execution is undefined. |
|
|
1120 | |
|
|
1121 | =head3 Watcher-Specific Functions and Data Members |
957 | |
1122 | |
958 | =over 4 |
1123 | =over 4 |
959 | |
1124 | |
960 | =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) |
961 | |
1126 | |
… | |
… | |
1057 | 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 |
1058 | 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 |
1059 | 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 () |
1060 | + 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 |
1061 | 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 |
1062 | roughly 10 seconds later and of course not if you reset your system time |
1227 | roughly 10 seconds later). |
1063 | again). |
|
|
1064 | |
1228 | |
1065 | 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 |
1066 | triggering an event on eahc midnight, local time. |
1230 | triggering an event on each midnight, local time or other, complicated, |
|
|
1231 | rules. |
1067 | |
1232 | |
1068 | 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 |
1069 | 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 |
1070 | during the same loop iteration then order of execution is undefined. |
1235 | during the same loop iteration then order of execution is undefined. |
1071 | |
1236 | |
|
|
1237 | =head3 Watcher-Specific Functions and Data Members |
|
|
1238 | |
1072 | =over 4 |
1239 | =over 4 |
1073 | |
1240 | |
1074 | =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) |
1075 | |
1242 | |
1076 | =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) |
… | |
… | |
1078 | 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 |
1079 | operation, and we will explain them from simplest to complex: |
1246 | operation, and we will explain them from simplest to complex: |
1080 | |
1247 | |
1081 | =over 4 |
1248 | =over 4 |
1082 | |
1249 | |
1083 | =item * absolute timer (interval = reschedule_cb = 0) |
1250 | =item * absolute timer (at = time, interval = reschedule_cb = 0) |
1084 | |
1251 | |
1085 | 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 |
1086 | 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, |
1087 | 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 |
1088 | system time reaches or surpasses this time. |
1255 | system time reaches or surpasses this time. |
1089 | |
1256 | |
1090 | =item * non-repeating interval timer (interval > 0, reschedule_cb = 0) |
1257 | =item * non-repeating interval timer (at = offset, interval > 0, reschedule_cb = 0) |
1091 | |
1258 | |
1092 | 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 |
1093 | 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) |
1094 | of any time jumps. |
1261 | and then repeat, regardless of any time jumps. |
1095 | |
1262 | |
1096 | 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 |
1097 | time: |
1264 | time: |
1098 | |
1265 | |
1099 | ev_periodic_set (&periodic, 0., 3600., 0); |
1266 | ev_periodic_set (&periodic, 0., 3600., 0); |
… | |
… | |
1105 | |
1272 | |
1106 | 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 |
1107 | 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 |
1108 | 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. |
1109 | |
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 | |
1110 | =item * manual reschedule mode (reschedule_cb = callback) |
1281 | =item * manual reschedule mode (at and interval ignored, reschedule_cb = callback) |
1111 | |
1282 | |
1112 | 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 |
1113 | ignored. Instead, each time the periodic watcher gets scheduled, the |
1284 | ignored. Instead, each time the periodic watcher gets scheduled, the |
1114 | 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 |
1115 | current time as second argument. |
1286 | current time as second argument. |
1116 | |
1287 | |
1117 | 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, |
1118 | 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, |
1119 | 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 |
1120 | starting a prepare watcher). |
1291 | starting an C<ev_prepare> watcher, which is legal). |
1121 | |
1292 | |
1122 | 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, |
1123 | ev_tstamp now)>, e.g.: |
1294 | ev_tstamp now)>, e.g.: |
1124 | |
1295 | |
1125 | 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) |
… | |
… | |
1148 | 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 |
1149 | when you changed some parameters or the reschedule callback would return |
1320 | when you changed some parameters or the reschedule callback would return |
1150 | 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 |
1151 | program when the crontabs have changed). |
1322 | program when the crontabs have changed). |
1152 | |
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 | |
1153 | =item ev_tstamp interval [read-write] |
1332 | =item ev_tstamp interval [read-write] |
1154 | |
1333 | |
1155 | 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 |
1156 | 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 |
1157 | called. |
1336 | called. |
… | |
… | |
1159 | =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] |
1160 | |
1339 | |
1161 | The current reschedule callback, or C<0>, if this functionality is |
1340 | The current reschedule callback, or C<0>, if this functionality is |
1162 | 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 |
1163 | 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. |
1164 | |
1348 | |
1165 | =back |
1349 | =back |
1166 | |
1350 | |
1167 | Example: Call a callback every hour, or, more precisely, whenever the |
1351 | Example: Call a callback every hour, or, more precisely, whenever the |
1168 | system clock is divisible by 3600. The callback invocation times have |
1352 | system clock is divisible by 3600. The callback invocation times have |
… | |
… | |
1210 | 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 |
1211 | 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 |
1212 | 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 |
1213 | SIG_DFL (regardless of what it was set to before). |
1397 | SIG_DFL (regardless of what it was set to before). |
1214 | |
1398 | |
|
|
1399 | =head3 Watcher-Specific Functions and Data Members |
|
|
1400 | |
1215 | =over 4 |
1401 | =over 4 |
1216 | |
1402 | |
1217 | =item ev_signal_init (ev_signal *, callback, int signum) |
1403 | =item ev_signal_init (ev_signal *, callback, int signum) |
1218 | |
1404 | |
1219 | =item ev_signal_set (ev_signal *, int signum) |
1405 | =item ev_signal_set (ev_signal *, int signum) |
… | |
… | |
1230 | |
1416 | |
1231 | =head2 C<ev_child> - watch out for process status changes |
1417 | =head2 C<ev_child> - watch out for process status changes |
1232 | |
1418 | |
1233 | 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 |
1234 | 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 |
1235 | |
1423 | |
1236 | =over 4 |
1424 | =over 4 |
1237 | |
1425 | |
1238 | =item ev_child_init (ev_child *, callback, int pid) |
1426 | =item ev_child_init (ev_child *, callback, int pid) |
1239 | |
1427 | |
… | |
… | |
1307 | 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 |
1308 | 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 |
1309 | 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 |
1310 | 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 |
1311 | 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 |
1312 | |
1519 | |
1313 | =over 4 |
1520 | =over 4 |
1314 | |
1521 | |
1315 | =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) |
1316 | |
1523 | |
… | |
… | |
1374 | } |
1581 | } |
1375 | |
1582 | |
1376 | ... |
1583 | ... |
1377 | ev_stat passwd; |
1584 | ev_stat passwd; |
1378 | |
1585 | |
1379 | ev_stat_init (&passwd, passwd_cb, "/etc/passwd"); |
1586 | ev_stat_init (&passwd, passwd_cb, "/etc/passwd", 0.); |
1380 | 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); |
1381 | |
1616 | |
1382 | |
1617 | |
1383 | =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... |
1384 | |
1619 | |
1385 | 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 |
… | |
… | |
1398 | |
1633 | |
1399 | Apart from keeping your process non-blocking (which is a useful |
1634 | Apart from keeping your process non-blocking (which is a useful |
1400 | 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 |
1401 | "pseudo-background processing", or delay processing stuff to after the |
1636 | "pseudo-background processing", or delay processing stuff to after the |
1402 | event loop has handled all outstanding events. |
1637 | event loop has handled all outstanding events. |
|
|
1638 | |
|
|
1639 | =head3 Watcher-Specific Functions and Data Members |
1403 | |
1640 | |
1404 | =over 4 |
1641 | =over 4 |
1405 | |
1642 | |
1406 | =item ev_idle_init (ev_signal *, callback) |
1643 | =item ev_idle_init (ev_signal *, callback) |
1407 | |
1644 | |
… | |
… | |
1465 | 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 |
1466 | 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 |
1467 | loop from blocking if lower-priority coroutines are active, thus mapping |
1704 | loop from blocking if lower-priority coroutines are active, thus mapping |
1468 | low-priority coroutines to idle/background tasks). |
1705 | low-priority coroutines to idle/background tasks). |
1469 | |
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 |
|
|
1718 | |
1470 | =over 4 |
1719 | =over 4 |
1471 | |
1720 | |
1472 | =item ev_prepare_init (ev_prepare *, callback) |
1721 | =item ev_prepare_init (ev_prepare *, callback) |
1473 | |
1722 | |
1474 | =item ev_check_init (ev_check *, callback) |
1723 | =item ev_check_init (ev_check *, callback) |
… | |
… | |
1477 | parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set> |
1726 | parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set> |
1478 | macros, but using them is utterly, utterly and completely pointless. |
1727 | macros, but using them is utterly, utterly and completely pointless. |
1479 | |
1728 | |
1480 | =back |
1729 | =back |
1481 | |
1730 | |
1482 | Example: To include a library such as adns, you would add IO watchers |
1731 | There are a number of principal ways to embed other event loops or modules |
1483 | and a timeout watcher in a prepare handler, as required by libadns, and |
1732 | into libev. Here are some ideas on how to include libadns into libev |
|
|
1733 | (there is a Perl module named C<EV::ADNS> that does this, which you could |
|
|
1734 | use for an actually working example. Another Perl module named C<EV::Glib> |
|
|
1735 | embeds a Glib main context into libev, and finally, C<Glib::EV> embeds EV |
|
|
1736 | into the Glib event loop). |
|
|
1737 | |
|
|
1738 | Method 1: Add IO watchers and a timeout watcher in a prepare handler, |
1484 | in a check watcher, destroy them and call into libadns. What follows is |
1739 | and in a check watcher, destroy them and call into libadns. What follows |
1485 | pseudo-code only of course: |
1740 | is pseudo-code only of course. This requires you to either use a low |
|
|
1741 | priority for the check watcher or use C<ev_clear_pending> explicitly, as |
|
|
1742 | the callbacks for the IO/timeout watchers might not have been called yet. |
1486 | |
1743 | |
1487 | static ev_io iow [nfd]; |
1744 | static ev_io iow [nfd]; |
1488 | static ev_timer tw; |
1745 | static ev_timer tw; |
1489 | |
1746 | |
1490 | static void |
1747 | static void |
1491 | io_cb (ev_loop *loop, ev_io *w, int revents) |
1748 | io_cb (ev_loop *loop, ev_io *w, int revents) |
1492 | { |
1749 | { |
1493 | // set the relevant poll flags |
|
|
1494 | // could also call adns_processreadable etc. here |
|
|
1495 | struct pollfd *fd = (struct pollfd *)w->data; |
|
|
1496 | if (revents & EV_READ ) fd->revents |= fd->events & POLLIN; |
|
|
1497 | if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT; |
|
|
1498 | } |
1750 | } |
1499 | |
1751 | |
1500 | // create io watchers for each fd and a timer before blocking |
1752 | // create io watchers for each fd and a timer before blocking |
1501 | static void |
1753 | static void |
1502 | adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) |
1754 | adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) |
… | |
… | |
1508 | |
1760 | |
1509 | /* the callback is illegal, but won't be called as we stop during check */ |
1761 | /* the callback is illegal, but won't be called as we stop during check */ |
1510 | ev_timer_init (&tw, 0, timeout * 1e-3); |
1762 | ev_timer_init (&tw, 0, timeout * 1e-3); |
1511 | ev_timer_start (loop, &tw); |
1763 | ev_timer_start (loop, &tw); |
1512 | |
1764 | |
1513 | // create on ev_io per pollfd |
1765 | // create one ev_io per pollfd |
1514 | for (int i = 0; i < nfd; ++i) |
1766 | for (int i = 0; i < nfd; ++i) |
1515 | { |
1767 | { |
1516 | ev_io_init (iow + i, io_cb, fds [i].fd, |
1768 | ev_io_init (iow + i, io_cb, fds [i].fd, |
1517 | ((fds [i].events & POLLIN ? EV_READ : 0) |
1769 | ((fds [i].events & POLLIN ? EV_READ : 0) |
1518 | | (fds [i].events & POLLOUT ? EV_WRITE : 0))); |
1770 | | (fds [i].events & POLLOUT ? EV_WRITE : 0))); |
1519 | |
1771 | |
1520 | fds [i].revents = 0; |
1772 | fds [i].revents = 0; |
1521 | iow [i].data = fds + i; |
|
|
1522 | ev_io_start (loop, iow + i); |
1773 | ev_io_start (loop, iow + i); |
1523 | } |
1774 | } |
1524 | } |
1775 | } |
1525 | |
1776 | |
1526 | // stop all watchers after blocking |
1777 | // stop all watchers after blocking |
… | |
… | |
1528 | adns_check_cb (ev_loop *loop, ev_check *w, int revents) |
1779 | adns_check_cb (ev_loop *loop, ev_check *w, int revents) |
1529 | { |
1780 | { |
1530 | ev_timer_stop (loop, &tw); |
1781 | ev_timer_stop (loop, &tw); |
1531 | |
1782 | |
1532 | for (int i = 0; i < nfd; ++i) |
1783 | for (int i = 0; i < nfd; ++i) |
|
|
1784 | { |
|
|
1785 | // set the relevant poll flags |
|
|
1786 | // could also call adns_processreadable etc. here |
|
|
1787 | struct pollfd *fd = fds + i; |
|
|
1788 | int revents = ev_clear_pending (iow + i); |
|
|
1789 | if (revents & EV_READ ) fd->revents |= fd->events & POLLIN; |
|
|
1790 | if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT; |
|
|
1791 | |
|
|
1792 | // now stop the watcher |
1533 | ev_io_stop (loop, iow + i); |
1793 | ev_io_stop (loop, iow + i); |
|
|
1794 | } |
1534 | |
1795 | |
1535 | adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop)); |
1796 | adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop)); |
|
|
1797 | } |
|
|
1798 | |
|
|
1799 | Method 2: This would be just like method 1, but you run C<adns_afterpoll> |
|
|
1800 | in the prepare watcher and would dispose of the check watcher. |
|
|
1801 | |
|
|
1802 | Method 3: If the module to be embedded supports explicit event |
|
|
1803 | notification (adns does), you can also make use of the actual watcher |
|
|
1804 | callbacks, and only destroy/create the watchers in the prepare watcher. |
|
|
1805 | |
|
|
1806 | static void |
|
|
1807 | timer_cb (EV_P_ ev_timer *w, int revents) |
|
|
1808 | { |
|
|
1809 | adns_state ads = (adns_state)w->data; |
|
|
1810 | update_now (EV_A); |
|
|
1811 | |
|
|
1812 | adns_processtimeouts (ads, &tv_now); |
|
|
1813 | } |
|
|
1814 | |
|
|
1815 | static void |
|
|
1816 | io_cb (EV_P_ ev_io *w, int revents) |
|
|
1817 | { |
|
|
1818 | adns_state ads = (adns_state)w->data; |
|
|
1819 | update_now (EV_A); |
|
|
1820 | |
|
|
1821 | if (revents & EV_READ ) adns_processreadable (ads, w->fd, &tv_now); |
|
|
1822 | if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now); |
|
|
1823 | } |
|
|
1824 | |
|
|
1825 | // do not ever call adns_afterpoll |
|
|
1826 | |
|
|
1827 | Method 4: Do not use a prepare or check watcher because the module you |
|
|
1828 | want to embed is too inflexible to support it. Instead, youc na override |
|
|
1829 | their poll function. The drawback with this solution is that the main |
|
|
1830 | loop is now no longer controllable by EV. The C<Glib::EV> module does |
|
|
1831 | this. |
|
|
1832 | |
|
|
1833 | static gint |
|
|
1834 | event_poll_func (GPollFD *fds, guint nfds, gint timeout) |
|
|
1835 | { |
|
|
1836 | int got_events = 0; |
|
|
1837 | |
|
|
1838 | for (n = 0; n < nfds; ++n) |
|
|
1839 | // create/start io watcher that sets the relevant bits in fds[n] and increment got_events |
|
|
1840 | |
|
|
1841 | if (timeout >= 0) |
|
|
1842 | // create/start timer |
|
|
1843 | |
|
|
1844 | // poll |
|
|
1845 | ev_loop (EV_A_ 0); |
|
|
1846 | |
|
|
1847 | // stop timer again |
|
|
1848 | if (timeout >= 0) |
|
|
1849 | ev_timer_stop (EV_A_ &to); |
|
|
1850 | |
|
|
1851 | // stop io watchers again - their callbacks should have set |
|
|
1852 | for (n = 0; n < nfds; ++n) |
|
|
1853 | ev_io_stop (EV_A_ iow [n]); |
|
|
1854 | |
|
|
1855 | return got_events; |
1536 | } |
1856 | } |
1537 | |
1857 | |
1538 | |
1858 | |
1539 | =head2 C<ev_embed> - when one backend isn't enough... |
1859 | =head2 C<ev_embed> - when one backend isn't enough... |
1540 | |
1860 | |
… | |
… | |
1604 | ev_embed_start (loop_hi, &embed); |
1924 | ev_embed_start (loop_hi, &embed); |
1605 | } |
1925 | } |
1606 | else |
1926 | else |
1607 | loop_lo = loop_hi; |
1927 | loop_lo = loop_hi; |
1608 | |
1928 | |
|
|
1929 | =head3 Watcher-Specific Functions and Data Members |
|
|
1930 | |
1609 | =over 4 |
1931 | =over 4 |
1610 | |
1932 | |
1611 | =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) |
1612 | |
1934 | |
1613 | =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) |
… | |
… | |
1622 | |
1944 | |
1623 | 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 |
1624 | 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 |
1625 | apropriate way for embedded loops. |
1947 | apropriate way for embedded loops. |
1626 | |
1948 | |
1627 | =item struct ev_loop *loop [read-only] |
1949 | =item struct ev_loop *other [read-only] |
1628 | |
1950 | |
1629 | The embedded event loop. |
1951 | The embedded event loop. |
1630 | |
1952 | |
1631 | =back |
1953 | =back |
1632 | |
1954 | |
… | |
… | |
1639 | 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, |
1640 | 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 |
1641 | 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 |
1642 | handlers will be invoked, too, of course. |
1964 | handlers will be invoked, too, of course. |
1643 | |
1965 | |
|
|
1966 | =head3 Watcher-Specific Functions and Data Members |
|
|
1967 | |
1644 | =over 4 |
1968 | =over 4 |
1645 | |
1969 | |
1646 | =item ev_fork_init (ev_signal *, callback) |
1970 | =item ev_fork_init (ev_signal *, callback) |
1647 | |
1971 | |
1648 | 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 |
… | |
… | |
1744 | |
2068 | |
1745 | To use it, |
2069 | To use it, |
1746 | |
2070 | |
1747 | #include <ev++.h> |
2071 | #include <ev++.h> |
1748 | |
2072 | |
1749 | (it is not installed by default). This automatically includes F<ev.h> |
2073 | This automatically includes F<ev.h> and puts all of its definitions (many |
1750 | and puts all of its definitions (many of them macros) into the global |
2074 | of them macros) into the global namespace. All C++ specific things are |
1751 | namespace. All C++ specific things are put into the C<ev> namespace. |
2075 | put into the C<ev> namespace. It should support all the same embedding |
|
|
2076 | options as F<ev.h>, most notably C<EV_MULTIPLICITY>. |
1752 | |
2077 | |
1753 | It should support all the same embedding options as F<ev.h>, most notably |
2078 | Care has been taken to keep the overhead low. The only data member the C++ |
1754 | C<EV_MULTIPLICITY>. |
2079 | classes add (compared to plain C-style watchers) is the event loop pointer |
|
|
2080 | that the watcher is associated with (or no additional members at all if |
|
|
2081 | you disable C<EV_MULTIPLICITY> when embedding libev). |
|
|
2082 | |
|
|
2083 | Currently, functions, and static and non-static member functions can be |
|
|
2084 | used as callbacks. Other types should be easy to add as long as they only |
|
|
2085 | need one additional pointer for context. If you need support for other |
|
|
2086 | types of functors please contact the author (preferably after implementing |
|
|
2087 | it). |
1755 | |
2088 | |
1756 | Here is a list of things available in the C<ev> namespace: |
2089 | Here is a list of things available in the C<ev> namespace: |
1757 | |
2090 | |
1758 | =over 4 |
2091 | =over 4 |
1759 | |
2092 | |
… | |
… | |
1775 | |
2108 | |
1776 | All of those classes have these methods: |
2109 | All of those classes have these methods: |
1777 | |
2110 | |
1778 | =over 4 |
2111 | =over 4 |
1779 | |
2112 | |
1780 | =item ev::TYPE::TYPE (object *, object::method *) |
2113 | =item ev::TYPE::TYPE () |
1781 | |
2114 | |
1782 | =item ev::TYPE::TYPE (object *, object::method *, struct ev_loop *) |
2115 | =item ev::TYPE::TYPE (struct ev_loop *) |
1783 | |
2116 | |
1784 | =item ev::TYPE::~TYPE |
2117 | =item ev::TYPE::~TYPE |
1785 | |
2118 | |
1786 | The constructor takes a pointer to an object and a method pointer to |
2119 | The constructor (optionally) takes an event loop to associate the watcher |
1787 | the event handler callback to call in this class. The constructor calls |
2120 | with. If it is omitted, it will use C<EV_DEFAULT>. |
1788 | C<ev_init> for you, which means you have to call the C<set> method |
2121 | |
1789 | before starting it. If you do not specify a loop then the constructor |
2122 | The constructor calls C<ev_init> for you, which means you have to call the |
1790 | automatically associates the default loop with this watcher. |
2123 | C<set> method before starting it. |
|
|
2124 | |
|
|
2125 | It will not set a callback, however: You have to call the templated C<set> |
|
|
2126 | method to set a callback before you can start the watcher. |
|
|
2127 | |
|
|
2128 | (The reason why you have to use a method is a limitation in C++ which does |
|
|
2129 | not allow explicit template arguments for constructors). |
1791 | |
2130 | |
1792 | The destructor automatically stops the watcher if it is active. |
2131 | The destructor automatically stops the watcher if it is active. |
|
|
2132 | |
|
|
2133 | =item w->set<class, &class::method> (object *) |
|
|
2134 | |
|
|
2135 | This method sets the callback method to call. The method has to have a |
|
|
2136 | signature of C<void (*)(ev_TYPE &, int)>, it receives the watcher as |
|
|
2137 | first argument and the C<revents> as second. The object must be given as |
|
|
2138 | parameter and is stored in the C<data> member of the watcher. |
|
|
2139 | |
|
|
2140 | This method synthesizes efficient thunking code to call your method from |
|
|
2141 | the C callback that libev requires. If your compiler can inline your |
|
|
2142 | callback (i.e. it is visible to it at the place of the C<set> call and |
|
|
2143 | your compiler is good :), then the method will be fully inlined into the |
|
|
2144 | thunking function, making it as fast as a direct C callback. |
|
|
2145 | |
|
|
2146 | Example: simple class declaration and watcher initialisation |
|
|
2147 | |
|
|
2148 | struct myclass |
|
|
2149 | { |
|
|
2150 | void io_cb (ev::io &w, int revents) { } |
|
|
2151 | } |
|
|
2152 | |
|
|
2153 | myclass obj; |
|
|
2154 | ev::io iow; |
|
|
2155 | iow.set <myclass, &myclass::io_cb> (&obj); |
|
|
2156 | |
|
|
2157 | =item w->set<function> (void *data = 0) |
|
|
2158 | |
|
|
2159 | Also sets a callback, but uses a static method or plain function as |
|
|
2160 | callback. The optional C<data> argument will be stored in the watcher's |
|
|
2161 | C<data> member and is free for you to use. |
|
|
2162 | |
|
|
2163 | The prototype of the C<function> must be C<void (*)(ev::TYPE &w, int)>. |
|
|
2164 | |
|
|
2165 | See the method-C<set> above for more details. |
|
|
2166 | |
|
|
2167 | Example: |
|
|
2168 | |
|
|
2169 | static void io_cb (ev::io &w, int revents) { } |
|
|
2170 | iow.set <io_cb> (); |
1793 | |
2171 | |
1794 | =item w->set (struct ev_loop *) |
2172 | =item w->set (struct ev_loop *) |
1795 | |
2173 | |
1796 | Associates a different C<struct ev_loop> with this watcher. You can only |
2174 | Associates a different C<struct ev_loop> with this watcher. You can only |
1797 | do this when the watcher is inactive (and not pending either). |
2175 | do this when the watcher is inactive (and not pending either). |
1798 | |
2176 | |
1799 | =item w->set ([args]) |
2177 | =item w->set ([args]) |
1800 | |
2178 | |
1801 | Basically the same as C<ev_TYPE_set>, with the same args. Must be |
2179 | Basically the same as C<ev_TYPE_set>, with the same args. Must be |
1802 | called at least once. Unlike the C counterpart, an active watcher gets |
2180 | called at least once. Unlike the C counterpart, an active watcher gets |
1803 | automatically stopped and restarted. |
2181 | automatically stopped and restarted when reconfiguring it with this |
|
|
2182 | method. |
1804 | |
2183 | |
1805 | =item w->start () |
2184 | =item w->start () |
1806 | |
2185 | |
1807 | Starts the watcher. Note that there is no C<loop> argument as the |
2186 | Starts the watcher. Note that there is no C<loop> argument, as the |
1808 | constructor already takes the loop. |
2187 | constructor already stores the event loop. |
1809 | |
2188 | |
1810 | =item w->stop () |
2189 | =item w->stop () |
1811 | |
2190 | |
1812 | 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. |
1813 | |
2192 | |
1814 | =item w->again () C<ev::timer>, C<ev::periodic> only |
2193 | =item w->again () (C<ev::timer>, C<ev::periodic> only) |
1815 | |
2194 | |
1816 | 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 |
1817 | C<ev_TYPE_again> function. |
2196 | C<ev_TYPE_again> function. |
1818 | |
2197 | |
1819 | =item w->sweep () C<ev::embed> only |
2198 | =item w->sweep () (C<ev::embed> only) |
1820 | |
2199 | |
1821 | Invokes C<ev_embed_sweep>. |
2200 | Invokes C<ev_embed_sweep>. |
1822 | |
2201 | |
1823 | =item w->update () C<ev::stat> only |
2202 | =item w->update () (C<ev::stat> only) |
1824 | |
2203 | |
1825 | Invokes C<ev_stat_stat>. |
2204 | Invokes C<ev_stat_stat>. |
1826 | |
2205 | |
1827 | =back |
2206 | =back |
1828 | |
2207 | |
… | |
… | |
1838 | |
2217 | |
1839 | myclass (); |
2218 | myclass (); |
1840 | } |
2219 | } |
1841 | |
2220 | |
1842 | myclass::myclass (int fd) |
2221 | myclass::myclass (int fd) |
1843 | : io (this, &myclass::io_cb), |
|
|
1844 | idle (this, &myclass::idle_cb) |
|
|
1845 | { |
2222 | { |
|
|
2223 | io .set <myclass, &myclass::io_cb > (this); |
|
|
2224 | idle.set <myclass, &myclass::idle_cb> (this); |
|
|
2225 | |
1846 | io.start (fd, ev::READ); |
2226 | io.start (fd, ev::READ); |
1847 | } |
2227 | } |
1848 | |
2228 | |
1849 | |
2229 | |
1850 | =head1 MACRO MAGIC |
2230 | =head1 MACRO MAGIC |
1851 | |
2231 | |
1852 | 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 |
1853 | C<EV_MULTIPLICITY>. This option determines whether (most) functions and |
2233 | of which is C<EV_MULTIPLICITY>. This option determines whether (most) |
1854 | callbacks have an initial C<struct ev_loop *> argument. |
2234 | functions and callbacks have an initial C<struct ev_loop *> argument. |
1855 | |
2235 | |
1856 | 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 |
1857 | following macros are defined: |
2237 | following macros are defined: |
1858 | |
2238 | |
1859 | =over 4 |
2239 | =over 4 |
… | |
… | |
1913 | Libev can (and often is) directly embedded into host |
2293 | Libev can (and often is) directly embedded into host |
1914 | applications. Examples of applications that embed it include the Deliantra |
2294 | applications. Examples of applications that embed it include the Deliantra |
1915 | 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) |
1916 | and rxvt-unicode. |
2296 | and rxvt-unicode. |
1917 | |
2297 | |
1918 | 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 |
1919 | 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 |
1920 | 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 |
1921 | libev somewhere in your source tree). |
2301 | libev somewhere in your source tree). |
1922 | |
2302 | |
1923 | =head2 FILESETS |
2303 | =head2 FILESETS |
… | |
… | |
2013 | |
2393 | |
2014 | 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 |
2015 | monotonic clock option at both compiletime and runtime. Otherwise no use |
2395 | monotonic clock option at both compiletime and runtime. Otherwise no use |
2016 | 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 |
2017 | 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 |
2018 | the functionality isn't available is safe, though, althoguh you have |
2398 | the functionality isn't available is safe, though, although you have |
2019 | 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> |
2020 | function is hiding in (often F<-lrt>). |
2400 | function is hiding in (often F<-lrt>). |
2021 | |
2401 | |
2022 | =item EV_USE_REALTIME |
2402 | =item EV_USE_REALTIME |
2023 | |
2403 | |
2024 | 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 |
2025 | realtime clock option at compiletime (and assume its availability at |
2405 | realtime clock option at compiletime (and assume its availability at |
2026 | 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 |
2027 | be attempted. This effectively replaces C<gettimeofday> by C<clock_get |
2407 | be attempted. This effectively replaces C<gettimeofday> by C<clock_get |
2028 | (CLOCK_REALTIME, ...)> and will not normally affect correctness. See tzhe note about libraries |
2408 | (CLOCK_REALTIME, ...)> and will not normally affect correctness. See the |
2029 | 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 ()>. |
2030 | |
2415 | |
2031 | =item EV_USE_SELECT |
2416 | =item EV_USE_SELECT |
2032 | |
2417 | |
2033 | 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 |
2034 | 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 |
… | |
… | |
2186 | 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 |
2187 | increase this value (I<must> be a power of two). |
2572 | increase this value (I<must> be a power of two). |
2188 | |
2573 | |
2189 | =item EV_INOTIFY_HASHSIZE |
2574 | =item EV_INOTIFY_HASHSIZE |
2190 | |
2575 | |
2191 | 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 |
2192 | 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>), |
2193 | 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> |
2194 | 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 |
2195 | two). |
2580 | two). |
2196 | |
2581 | |
… | |
… | |
2213 | |
2598 | |
2214 | =item ev_set_cb (ev, cb) |
2599 | =item ev_set_cb (ev, cb) |
2215 | |
2600 | |
2216 | 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, |
2217 | 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 |
2218 | 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 |
2219 | their default definitions. One possible use for overriding these is to |
2604 | their default definitions. One possible use for overriding these is to |
2220 | 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 |
2221 | 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 | ... |
2222 | |
2632 | |
2223 | =head2 EXAMPLES |
2633 | =head2 EXAMPLES |
2224 | |
2634 | |
2225 | For a real-world example of a program the includes libev |
2635 | For a real-world example of a program the includes libev |
2226 | verbatim, you can have a look at the EV perl module |
2636 | verbatim, you can have a look at the EV perl module |
… | |
… | |
2255 | |
2665 | |
2256 | In this section the complexities of (many of) the algorithms used inside |
2666 | In this section the complexities of (many of) the algorithms used inside |
2257 | libev will be explained. For complexity discussions about backends see the |
2667 | libev will be explained. For complexity discussions about backends see the |
2258 | documentation for C<ev_default_init>. |
2668 | documentation for C<ev_default_init>. |
2259 | |
2669 | |
|
|
2670 | All of the following are about amortised time: If an array needs to be |
|
|
2671 | extended, libev needs to realloc and move the whole array, but this |
|
|
2672 | happens asymptotically never with higher number of elements, so O(1) might |
|
|
2673 | mean it might do a lengthy realloc operation in rare cases, but on average |
|
|
2674 | it is much faster and asymptotically approaches constant time. |
|
|
2675 | |
2260 | =over 4 |
2676 | =over 4 |
2261 | |
2677 | |
2262 | =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) |
2263 | |
2679 | |
2264 | 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 |
2265 | 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 |
2266 | have to skip those 100 watchers. |
2682 | have to skip roughly seven (C<ld 100>) of these watchers. |
2267 | |
2683 | |
2268 | =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) |
2269 | |
2685 | |
2270 | 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 |
2271 | 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. |
2272 | |
2688 | |
2273 | =item Starting io/check/prepare/idle/signal/child watchers: O(1) |
2689 | =item Starting io/check/prepare/idle/signal/child watchers: O(1) |
2274 | |
2690 | |
2275 | These just add the watcher into an array or at the head of a list. If |
2691 | These just add the watcher into an array or at the head of a list. |
2276 | the array needs to be extended libev needs to realloc and move the whole |
|
|
2277 | array, but this happen asymptotically less and less with more watchers, |
|
|
2278 | thus amortised O(1). |
|
|
2279 | |
2692 | |
2280 | =item Stopping check/prepare/idle watchers: O(1) |
2693 | =item Stopping check/prepare/idle watchers: O(1) |
2281 | |
2694 | |
2282 | =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)) |
2283 | |
2696 | |
2284 | 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 |
2285 | 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 |
2286 | have many watchers waiting for the same fd or signal). |
2699 | have many watchers waiting for the same fd or signal). |
2287 | |
2700 | |
2288 | =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. |
2289 | |
2705 | |
2290 | =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) |
2291 | |
2707 | |
2292 | 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 |
2293 | 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). |
2294 | |
2711 | |
2295 | =item Activating one watcher: O(1) |
2712 | =item Activating one watcher (putting it into the pending state): O(1) |
2296 | |
2713 | |
2297 | =item Priority handling: O(number_of_priorities) |
2714 | =item Priority handling: O(number_of_priorities) |
2298 | |
2715 | |
2299 | Priorities are implemented by allocating some space for each |
2716 | Priorities are implemented by allocating some space for each |
2300 | priority. When doing priority-based operations, libev usually has to |
2717 | priority. When doing priority-based operations, libev usually has to |
2301 | 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. |
2302 | |
2720 | |
2303 | =back |
2721 | =back |
2304 | |
2722 | |
2305 | |
2723 | |
2306 | =head1 AUTHOR |
2724 | =head1 AUTHOR |