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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; |
… | |
… | |
48 | return 0; |
48 | return 0; |
49 | } |
49 | } |
50 | |
50 | |
51 | =head1 DESCRIPTION |
51 | =head1 DESCRIPTION |
52 | |
52 | |
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53 | The newest version of this document is also available as a html-formatted |
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54 | web page you might find easier to navigate when reading it for the first |
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55 | time: L<http://cvs.schmorp.de/libev/ev.html>. |
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56 | |
53 | 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 |
54 | 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 |
55 | these event sources and provide your program with events. |
59 | these event sources and provide your program with events. |
56 | |
60 | |
57 | 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 |
58 | (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 |
59 | communicate events via a callback mechanism. |
63 | communicate events via a callback mechanism. |
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61 | 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 |
62 | watchers>, which are relatively small C structures you initialise with the |
66 | watchers>, which are relatively small C structures you initialise with the |
63 | 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 |
64 | watcher. |
68 | watcher. |
65 | |
69 | |
66 | =head1 FEATURES |
70 | =head2 FEATURES |
67 | |
71 | |
68 | 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 |
69 | BSD-specific C<kqueue> and the Solaris-specific event port mechanisms |
73 | BSD-specific C<kqueue> and the Solaris-specific event port mechanisms |
70 | 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 |
71 | (for C<ev_stat>), relative timers (C<ev_timer>), absolute timers |
75 | (for C<ev_stat>), relative timers (C<ev_timer>), absolute timers |
… | |
… | |
78 | |
82 | |
79 | It also is quite fast (see this |
83 | It also is quite fast (see this |
80 | 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 |
81 | for example). |
85 | for example). |
82 | |
86 | |
83 | =head1 CONVENTIONS |
87 | =head2 CONVENTIONS |
84 | |
88 | |
85 | Libev is very configurable. In this manual the default configuration will |
89 | Libev is very configurable. In this manual the default configuration will |
86 | be described, which supports multiple event loops. For more info about |
90 | be described, which supports multiple event loops. For more info about |
87 | 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 |
88 | this manual. If libev was configured without support for multiple event |
92 | this manual. If libev was configured without support for multiple event |
89 | 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> |
90 | (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. |
91 | |
95 | |
92 | =head1 TIME REPRESENTATION |
96 | =head2 TIME REPRESENTATION |
93 | |
97 | |
94 | Libev represents time as a single floating point number, representing the |
98 | Libev represents time as a single floating point number, representing the |
95 | (fractional) number of seconds since the (POSIX) epoch (somewhere near |
99 | (fractional) number of seconds since the (POSIX) epoch (somewhere near |
96 | 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 |
97 | 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 |
98 | 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 |
99 | 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. |
100 | |
106 | |
101 | =head1 GLOBAL FUNCTIONS |
107 | =head1 GLOBAL FUNCTIONS |
102 | |
108 | |
103 | These functions can be called anytime, even before initialising the |
109 | These functions can be called anytime, even before initialising the |
104 | library in any way. |
110 | library in any way. |
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109 | |
115 | |
110 | 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 |
111 | 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 |
112 | you actually want to know. |
118 | you actually want to know. |
113 | |
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 | |
114 | =item int ev_version_major () |
126 | =item int ev_version_major () |
115 | |
127 | |
116 | =item int ev_version_minor () |
128 | =item int ev_version_minor () |
117 | |
129 | |
118 | 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 |
119 | 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 |
120 | 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 |
121 | 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 |
122 | version of the library your program was compiled against. |
134 | version of the library your program was compiled against. |
123 | |
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 | |
124 | 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, |
125 | as this indicates an incompatible change. Minor versions are usually |
140 | as this indicates an incompatible change. Minor versions are usually |
126 | 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 |
127 | not a problem. |
142 | not a problem. |
128 | |
143 | |
129 | 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 |
130 | version. |
145 | version. |
… | |
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274 | a fork, you can also make libev check for a fork in each iteration by |
289 | a fork, you can also make libev check for a fork in each iteration by |
275 | enabling this flag. |
290 | enabling this flag. |
276 | |
291 | |
277 | This works by calling C<getpid ()> on every iteration of the loop, |
292 | This works by calling C<getpid ()> on every iteration of the loop, |
278 | and thus this might slow down your event loop if you do a lot of loop |
293 | and thus this might slow down your event loop if you do a lot of loop |
279 | iterations and little real work, but is usually not noticable (on my |
294 | iterations and little real work, but is usually not noticeable (on my |
280 | Linux system for example, C<getpid> is actually a simple 5-insn sequence |
295 | Linux system for example, C<getpid> is actually a simple 5-insn sequence |
281 | without a syscall and thus I<very> fast, but my Linux system also has |
296 | without a syscall and thus I<very> fast, but my Linux system also has |
282 | C<pthread_atfork> which is even faster). |
297 | C<pthread_atfork> which is even faster). |
283 | |
298 | |
284 | The big advantage of this flag is that you can forget about fork (and |
299 | The big advantage of this flag is that you can forget about fork (and |
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291 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
306 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
292 | |
307 | |
293 | 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 |
294 | 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, |
295 | 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 |
296 | 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 |
297 | 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. |
298 | |
320 | |
299 | =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) |
300 | |
322 | |
301 | 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 |
302 | 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 |
303 | 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 |
304 | 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. |
305 | |
329 | |
306 | =item C<EVBACKEND_EPOLL> (value 4, Linux) |
330 | =item C<EVBACKEND_EPOLL> (value 4, Linux) |
307 | |
331 | |
308 | 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, |
309 | but it scales phenomenally better. While poll and select usually scale like |
333 | but it scales phenomenally better. While poll and select usually scale |
310 | 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), |
311 | 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. |
312 | |
339 | |
313 | 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 |
314 | 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 |
315 | (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 |
316 | 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 |
317 | well if you register events for both fds. |
344 | very well if you register events for both fds. |
318 | |
345 | |
319 | Please note that epoll sometimes generates spurious notifications, so you |
346 | Please note that epoll sometimes generates spurious notifications, so you |
320 | 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 |
321 | (or space) is available. |
348 | (or space) is available. |
322 | |
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 | |
323 | =item C<EVBACKEND_KQUEUE> (value 8, most BSD clones) |
357 | =item C<EVBACKEND_KQUEUE> (value 8, most BSD clones) |
324 | |
358 | |
325 | 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 |
326 | 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 |
327 | 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 |
328 | completely useless). For this reason its not being "autodetected" |
362 | it's completely useless). For this reason it's not being "autodetected" |
329 | 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 |
330 | 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. |
331 | |
370 | |
332 | 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 |
333 | 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 |
334 | 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 |
335 | 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 |
336 | 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. |
337 | |
386 | |
338 | =item C<EVBACKEND_DEVPOLL> (value 16, Solaris 8) |
387 | =item C<EVBACKEND_DEVPOLL> (value 16, Solaris 8) |
339 | |
388 | |
340 | 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. |
341 | |
393 | |
342 | =item C<EVBACKEND_PORT> (value 32, Solaris 10) |
394 | =item C<EVBACKEND_PORT> (value 32, Solaris 10) |
343 | |
395 | |
344 | 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, |
345 | 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)). |
346 | |
398 | |
347 | 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 |
348 | 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 |
349 | 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. |
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407 | |
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408 | On the positive side, ignoring the spurious readyness notifications, this |
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409 | backend actually performed to specification in all tests and is fully |
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410 | embeddable, which is a rare feat among the OS-specific backends. |
350 | |
411 | |
351 | =item C<EVBACKEND_ALL> |
412 | =item C<EVBACKEND_ALL> |
352 | |
413 | |
353 | Try all backends (even potentially broken ones that wouldn't be tried |
414 | Try all backends (even potentially broken ones that wouldn't be tried |
354 | with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as |
415 | with C<EVFLAG_AUTO>). Since this is a mask, you can do stuff such as |
355 | C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>. |
416 | C<EVBACKEND_ALL & ~EVBACKEND_KQUEUE>. |
356 | |
417 | |
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418 | It is definitely not recommended to use this flag. |
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419 | |
357 | =back |
420 | =back |
358 | |
421 | |
359 | If one or more of these are ored into the flags value, then only these |
422 | If one or more of these are ored into the flags value, then only these |
360 | backends will be tried (in the reverse order as given here). If none are |
423 | backends will be tried (in the reverse order as listed here). If none are |
361 | specified, most compiled-in backend will be tried, usually in reverse |
424 | specified, all backends in C<ev_recommended_backends ()> will be tried. |
362 | order of their flag values :) |
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363 | |
425 | |
364 | The most typical usage is like this: |
426 | The most typical usage is like this: |
365 | |
427 | |
366 | if (!ev_default_loop (0)) |
428 | if (!ev_default_loop (0)) |
367 | fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?"); |
429 | fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?"); |
… | |
… | |
395 | Destroys the default loop again (frees all memory and kernel state |
457 | Destroys the default loop again (frees all memory and kernel state |
396 | etc.). None of the active event watchers will be stopped in the normal |
458 | etc.). None of the active event watchers will be stopped in the normal |
397 | sense, so e.g. C<ev_is_active> might still return true. It is your |
459 | sense, so e.g. C<ev_is_active> might still return true. It is your |
398 | responsibility to either stop all watchers cleanly yoursef I<before> |
460 | responsibility to either stop all watchers cleanly yoursef I<before> |
399 | calling this function, or cope with the fact afterwards (which is usually |
461 | calling this function, or cope with the fact afterwards (which is usually |
400 | the easiest thing, youc na just ignore the watchers and/or C<free ()> them |
462 | the easiest thing, you can just ignore the watchers and/or C<free ()> them |
401 | for example). |
463 | for example). |
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464 | |
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465 | Note that certain global state, such as signal state, will not be freed by |
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466 | this function, and related watchers (such as signal and child watchers) |
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467 | would need to be stopped manually. |
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468 | |
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469 | In general it is not advisable to call this function except in the |
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470 | rare occasion where you really need to free e.g. the signal handling |
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471 | pipe fds. If you need dynamically allocated loops it is better to use |
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472 | C<ev_loop_new> and C<ev_loop_destroy>). |
402 | |
473 | |
403 | =item ev_loop_destroy (loop) |
474 | =item ev_loop_destroy (loop) |
404 | |
475 | |
405 | Like C<ev_default_destroy>, but destroys an event loop created by an |
476 | Like C<ev_default_destroy>, but destroys an event loop created by an |
406 | earlier call to C<ev_loop_new>. |
477 | earlier call to C<ev_loop_new>. |
… | |
… | |
430 | |
501 | |
431 | Like C<ev_default_fork>, but acts on an event loop created by |
502 | Like C<ev_default_fork>, but acts on an event loop created by |
432 | C<ev_loop_new>. Yes, you have to call this on every allocated event loop |
503 | C<ev_loop_new>. Yes, you have to call this on every allocated event loop |
433 | after fork, and how you do this is entirely your own problem. |
504 | after fork, and how you do this is entirely your own problem. |
434 | |
505 | |
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506 | =item unsigned int ev_loop_count (loop) |
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507 | |
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508 | Returns the count of loop iterations for the loop, which is identical to |
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509 | the number of times libev did poll for new events. It starts at C<0> and |
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510 | happily wraps around with enough iterations. |
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511 | |
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512 | This value can sometimes be useful as a generation counter of sorts (it |
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513 | "ticks" the number of loop iterations), as it roughly corresponds with |
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514 | C<ev_prepare> and C<ev_check> calls. |
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515 | |
435 | =item unsigned int ev_backend (loop) |
516 | =item unsigned int ev_backend (loop) |
436 | |
517 | |
437 | Returns one of the C<EVBACKEND_*> flags indicating the event backend in |
518 | Returns one of the C<EVBACKEND_*> flags indicating the event backend in |
438 | use. |
519 | use. |
439 | |
520 | |
… | |
… | |
441 | |
522 | |
442 | Returns the current "event loop time", which is the time the event loop |
523 | Returns the current "event loop time", which is the time the event loop |
443 | received events and started processing them. This timestamp does not |
524 | received events and started processing them. This timestamp does not |
444 | change as long as callbacks are being processed, and this is also the base |
525 | change as long as callbacks are being processed, and this is also the base |
445 | time used for relative timers. You can treat it as the timestamp of the |
526 | time used for relative timers. You can treat it as the timestamp of the |
446 | event occuring (or more correctly, libev finding out about it). |
527 | event occurring (or more correctly, libev finding out about it). |
447 | |
528 | |
448 | =item ev_loop (loop, int flags) |
529 | =item ev_loop (loop, int flags) |
449 | |
530 | |
450 | Finally, this is it, the event handler. This function usually is called |
531 | Finally, this is it, the event handler. This function usually is called |
451 | after you initialised all your watchers and you want to start handling |
532 | after you initialised all your watchers and you want to start handling |
… | |
… | |
472 | libev watchers. However, a pair of C<ev_prepare>/C<ev_check> watchers is |
553 | libev watchers. However, a pair of C<ev_prepare>/C<ev_check> watchers is |
473 | usually a better approach for this kind of thing. |
554 | usually a better approach for this kind of thing. |
474 | |
555 | |
475 | Here are the gory details of what C<ev_loop> does: |
556 | Here are the gory details of what C<ev_loop> does: |
476 | |
557 | |
477 | * If there are no active watchers (reference count is zero), return. |
558 | - Before the first iteration, call any pending watchers. |
478 | - Queue prepare watchers and then call all outstanding watchers. |
559 | * If EVFLAG_FORKCHECK was used, check for a fork. |
|
|
560 | - If a fork was detected, queue and call all fork watchers. |
|
|
561 | - Queue and call all prepare watchers. |
479 | - If we have been forked, recreate the kernel state. |
562 | - If we have been forked, recreate the kernel state. |
480 | - Update the kernel state with all outstanding changes. |
563 | - Update the kernel state with all outstanding changes. |
481 | - Update the "event loop time". |
564 | - Update the "event loop time". |
482 | - Calculate for how long to block. |
565 | - Calculate for how long to sleep or block, if at all |
|
|
566 | (active idle watchers, EVLOOP_NONBLOCK or not having |
|
|
567 | any active watchers at all will result in not sleeping). |
|
|
568 | - Sleep if the I/O and timer collect interval say so. |
483 | - Block the process, waiting for any events. |
569 | - Block the process, waiting for any events. |
484 | - Queue all outstanding I/O (fd) events. |
570 | - Queue all outstanding I/O (fd) events. |
485 | - Update the "event loop time" and do time jump handling. |
571 | - Update the "event loop time" and do time jump handling. |
486 | - Queue all outstanding timers. |
572 | - Queue all outstanding timers. |
487 | - Queue all outstanding periodics. |
573 | - Queue all outstanding periodics. |
488 | - If no events are pending now, queue all idle watchers. |
574 | - If no events are pending now, queue all idle watchers. |
489 | - Queue all check watchers. |
575 | - Queue all check watchers. |
490 | - Call all queued watchers in reverse order (i.e. check watchers first). |
576 | - Call all queued watchers in reverse order (i.e. check watchers first). |
491 | Signals and child watchers are implemented as I/O watchers, and will |
577 | Signals and child watchers are implemented as I/O watchers, and will |
492 | be handled here by queueing them when their watcher gets executed. |
578 | be handled here by queueing them when their watcher gets executed. |
493 | - If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
579 | - If ev_unloop has been called, or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
494 | were used, return, otherwise continue with step *. |
580 | were used, or there are no active watchers, return, otherwise |
|
|
581 | continue with step *. |
495 | |
582 | |
496 | Example: Queue some jobs and then loop until no events are outsanding |
583 | Example: Queue some jobs and then loop until no events are outstanding |
497 | anymore. |
584 | anymore. |
498 | |
585 | |
499 | ... queue jobs here, make sure they register event watchers as long |
586 | ... queue jobs here, make sure they register event watchers as long |
500 | ... as they still have work to do (even an idle watcher will do..) |
587 | ... as they still have work to do (even an idle watcher will do..) |
501 | ev_loop (my_loop, 0); |
588 | ev_loop (my_loop, 0); |
… | |
… | |
505 | |
592 | |
506 | Can be used to make a call to C<ev_loop> return early (but only after it |
593 | Can be used to make a call to C<ev_loop> return early (but only after it |
507 | has processed all outstanding events). The C<how> argument must be either |
594 | has processed all outstanding events). The C<how> argument must be either |
508 | C<EVUNLOOP_ONE>, which will make the innermost C<ev_loop> call return, or |
595 | C<EVUNLOOP_ONE>, which will make the innermost C<ev_loop> call return, or |
509 | C<EVUNLOOP_ALL>, which will make all nested C<ev_loop> calls return. |
596 | C<EVUNLOOP_ALL>, which will make all nested C<ev_loop> calls return. |
|
|
597 | |
|
|
598 | This "unloop state" will be cleared when entering C<ev_loop> again. |
510 | |
599 | |
511 | =item ev_ref (loop) |
600 | =item ev_ref (loop) |
512 | |
601 | |
513 | =item ev_unref (loop) |
602 | =item ev_unref (loop) |
514 | |
603 | |
… | |
… | |
519 | returning, ev_unref() after starting, and ev_ref() before stopping it. For |
608 | returning, ev_unref() after starting, and ev_ref() before stopping it. For |
520 | example, libev itself uses this for its internal signal pipe: It is not |
609 | example, libev itself uses this for its internal signal pipe: It is not |
521 | visible to the libev user and should not keep C<ev_loop> from exiting if |
610 | visible to the libev user and should not keep C<ev_loop> from exiting if |
522 | no event watchers registered by it are active. It is also an excellent |
611 | no event watchers registered by it are active. It is also an excellent |
523 | way to do this for generic recurring timers or from within third-party |
612 | way to do this for generic recurring timers or from within third-party |
524 | libraries. Just remember to I<unref after start> and I<ref before stop>. |
613 | libraries. Just remember to I<unref after start> and I<ref before stop> |
|
|
614 | (but only if the watcher wasn't active before, or was active before, |
|
|
615 | respectively). |
525 | |
616 | |
526 | Example: Create a signal watcher, but keep it from keeping C<ev_loop> |
617 | Example: Create a signal watcher, but keep it from keeping C<ev_loop> |
527 | running when nothing else is active. |
618 | running when nothing else is active. |
528 | |
619 | |
529 | struct ev_signal exitsig; |
620 | struct ev_signal exitsig; |
… | |
… | |
533 | |
624 | |
534 | Example: For some weird reason, unregister the above signal handler again. |
625 | Example: For some weird reason, unregister the above signal handler again. |
535 | |
626 | |
536 | ev_ref (loop); |
627 | ev_ref (loop); |
537 | ev_signal_stop (loop, &exitsig); |
628 | ev_signal_stop (loop, &exitsig); |
|
|
629 | |
|
|
630 | =item ev_set_io_collect_interval (loop, ev_tstamp interval) |
|
|
631 | |
|
|
632 | =item ev_set_timeout_collect_interval (loop, ev_tstamp interval) |
|
|
633 | |
|
|
634 | These advanced functions influence the time that libev will spend waiting |
|
|
635 | for events. Both are by default C<0>, meaning that libev will try to |
|
|
636 | invoke timer/periodic callbacks and I/O callbacks with minimum latency. |
|
|
637 | |
|
|
638 | Setting these to a higher value (the C<interval> I<must> be >= C<0>) |
|
|
639 | allows libev to delay invocation of I/O and timer/periodic callbacks to |
|
|
640 | increase efficiency of loop iterations. |
|
|
641 | |
|
|
642 | The background is that sometimes your program runs just fast enough to |
|
|
643 | handle one (or very few) event(s) per loop iteration. While this makes |
|
|
644 | the program responsive, it also wastes a lot of CPU time to poll for new |
|
|
645 | events, especially with backends like C<select ()> which have a high |
|
|
646 | overhead for the actual polling but can deliver many events at once. |
|
|
647 | |
|
|
648 | By setting a higher I<io collect interval> you allow libev to spend more |
|
|
649 | time collecting I/O events, so you can handle more events per iteration, |
|
|
650 | at the cost of increasing latency. Timeouts (both C<ev_periodic> and |
|
|
651 | C<ev_timer>) will be not affected. Setting this to a non-null value will |
|
|
652 | introduce an additional C<ev_sleep ()> call into most loop iterations. |
|
|
653 | |
|
|
654 | Likewise, by setting a higher I<timeout collect interval> you allow libev |
|
|
655 | to spend more time collecting timeouts, at the expense of increased |
|
|
656 | latency (the watcher callback will be called later). C<ev_io> watchers |
|
|
657 | will not be affected. Setting this to a non-null value will not introduce |
|
|
658 | any overhead in libev. |
|
|
659 | |
|
|
660 | Many (busy) programs can usually benefit by setting the io collect |
|
|
661 | interval to a value near C<0.1> or so, which is often enough for |
|
|
662 | interactive servers (of course not for games), likewise for timeouts. It |
|
|
663 | usually doesn't make much sense to set it to a lower value than C<0.01>, |
|
|
664 | as this approsaches the timing granularity of most systems. |
538 | |
665 | |
539 | =back |
666 | =back |
540 | |
667 | |
541 | |
668 | |
542 | =head1 ANATOMY OF A WATCHER |
669 | =head1 ANATOMY OF A WATCHER |
… | |
… | |
722 | =item bool ev_is_pending (ev_TYPE *watcher) |
849 | =item bool ev_is_pending (ev_TYPE *watcher) |
723 | |
850 | |
724 | Returns a true value iff the watcher is pending, (i.e. it has outstanding |
851 | Returns a true value iff the watcher is pending, (i.e. it has outstanding |
725 | events but its callback has not yet been invoked). As long as a watcher |
852 | events but its callback has not yet been invoked). As long as a watcher |
726 | is pending (but not active) you must not call an init function on it (but |
853 | is pending (but not active) you must not call an init function on it (but |
727 | C<ev_TYPE_set> is safe) and you must make sure the watcher is available to |
854 | C<ev_TYPE_set> is safe), you must not change its priority, and you must |
728 | libev (e.g. you cnanot C<free ()> it). |
855 | make sure the watcher is available to libev (e.g. you cannot C<free ()> |
|
|
856 | it). |
729 | |
857 | |
730 | =item callback ev_cb (ev_TYPE *watcher) |
858 | =item callback ev_cb (ev_TYPE *watcher) |
731 | |
859 | |
732 | Returns the callback currently set on the watcher. |
860 | Returns the callback currently set on the watcher. |
733 | |
861 | |
734 | =item ev_cb_set (ev_TYPE *watcher, callback) |
862 | =item ev_cb_set (ev_TYPE *watcher, callback) |
735 | |
863 | |
736 | Change the callback. You can change the callback at virtually any time |
864 | Change the callback. You can change the callback at virtually any time |
737 | (modulo threads). |
865 | (modulo threads). |
|
|
866 | |
|
|
867 | =item ev_set_priority (ev_TYPE *watcher, priority) |
|
|
868 | |
|
|
869 | =item int ev_priority (ev_TYPE *watcher) |
|
|
870 | |
|
|
871 | Set and query the priority of the watcher. The priority is a small |
|
|
872 | integer between C<EV_MAXPRI> (default: C<2>) and C<EV_MINPRI> |
|
|
873 | (default: C<-2>). Pending watchers with higher priority will be invoked |
|
|
874 | before watchers with lower priority, but priority will not keep watchers |
|
|
875 | from being executed (except for C<ev_idle> watchers). |
|
|
876 | |
|
|
877 | This means that priorities are I<only> used for ordering callback |
|
|
878 | invocation after new events have been received. This is useful, for |
|
|
879 | example, to reduce latency after idling, or more often, to bind two |
|
|
880 | watchers on the same event and make sure one is called first. |
|
|
881 | |
|
|
882 | If you need to suppress invocation when higher priority events are pending |
|
|
883 | you need to look at C<ev_idle> watchers, which provide this functionality. |
|
|
884 | |
|
|
885 | You I<must not> change the priority of a watcher as long as it is active or |
|
|
886 | pending. |
|
|
887 | |
|
|
888 | The default priority used by watchers when no priority has been set is |
|
|
889 | always C<0>, which is supposed to not be too high and not be too low :). |
|
|
890 | |
|
|
891 | Setting a priority outside the range of C<EV_MINPRI> to C<EV_MAXPRI> is |
|
|
892 | fine, as long as you do not mind that the priority value you query might |
|
|
893 | or might not have been adjusted to be within valid range. |
|
|
894 | |
|
|
895 | =item ev_invoke (loop, ev_TYPE *watcher, int revents) |
|
|
896 | |
|
|
897 | Invoke the C<watcher> with the given C<loop> and C<revents>. Neither |
|
|
898 | C<loop> nor C<revents> need to be valid as long as the watcher callback |
|
|
899 | can deal with that fact. |
|
|
900 | |
|
|
901 | =item int ev_clear_pending (loop, ev_TYPE *watcher) |
|
|
902 | |
|
|
903 | If the watcher is pending, this function returns clears its pending status |
|
|
904 | and returns its C<revents> bitset (as if its callback was invoked). If the |
|
|
905 | watcher isn't pending it does nothing and returns C<0>. |
738 | |
906 | |
739 | =back |
907 | =back |
740 | |
908 | |
741 | |
909 | |
742 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
910 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
… | |
… | |
827 | In general you can register as many read and/or write event watchers per |
995 | In general you can register as many read and/or write event watchers per |
828 | fd as you want (as long as you don't confuse yourself). Setting all file |
996 | fd as you want (as long as you don't confuse yourself). Setting all file |
829 | descriptors to non-blocking mode is also usually a good idea (but not |
997 | descriptors to non-blocking mode is also usually a good idea (but not |
830 | required if you know what you are doing). |
998 | required if you know what you are doing). |
831 | |
999 | |
832 | You have to be careful with dup'ed file descriptors, though. Some backends |
|
|
833 | (the linux epoll backend is a notable example) cannot handle dup'ed file |
|
|
834 | descriptors correctly if you register interest in two or more fds pointing |
|
|
835 | to the same underlying file/socket/etc. description (that is, they share |
|
|
836 | the same underlying "file open"). |
|
|
837 | |
|
|
838 | If you must do this, then force the use of a known-to-be-good backend |
1000 | If you must do this, then force the use of a known-to-be-good backend |
839 | (at the time of this writing, this includes only C<EVBACKEND_SELECT> and |
1001 | (at the time of this writing, this includes only C<EVBACKEND_SELECT> and |
840 | C<EVBACKEND_POLL>). |
1002 | C<EVBACKEND_POLL>). |
841 | |
1003 | |
842 | Another thing you have to watch out for is that it is quite easy to |
1004 | Another thing you have to watch out for is that it is quite easy to |
… | |
… | |
848 | it is best to always use non-blocking I/O: An extra C<read>(2) returning |
1010 | it is best to always use non-blocking I/O: An extra C<read>(2) returning |
849 | C<EAGAIN> is far preferable to a program hanging until some data arrives. |
1011 | C<EAGAIN> is far preferable to a program hanging until some data arrives. |
850 | |
1012 | |
851 | If you cannot run the fd in non-blocking mode (for example you should not |
1013 | If you cannot run the fd in non-blocking mode (for example you should not |
852 | play around with an Xlib connection), then you have to seperately re-test |
1014 | play around with an Xlib connection), then you have to seperately re-test |
853 | wether a file descriptor is really ready with a known-to-be good interface |
1015 | whether a file descriptor is really ready with a known-to-be good interface |
854 | such as poll (fortunately in our Xlib example, Xlib already does this on |
1016 | such as poll (fortunately in our Xlib example, Xlib already does this on |
855 | its own, so its quite safe to use). |
1017 | its own, so its quite safe to use). |
|
|
1018 | |
|
|
1019 | =head3 The special problem of disappearing file descriptors |
|
|
1020 | |
|
|
1021 | Some backends (e.g. kqueue, epoll) need to be told about closing a file |
|
|
1022 | descriptor (either by calling C<close> explicitly or by any other means, |
|
|
1023 | such as C<dup>). The reason is that you register interest in some file |
|
|
1024 | descriptor, but when it goes away, the operating system will silently drop |
|
|
1025 | this interest. If another file descriptor with the same number then is |
|
|
1026 | registered with libev, there is no efficient way to see that this is, in |
|
|
1027 | fact, a different file descriptor. |
|
|
1028 | |
|
|
1029 | To avoid having to explicitly tell libev about such cases, libev follows |
|
|
1030 | the following policy: Each time C<ev_io_set> is being called, libev |
|
|
1031 | will assume that this is potentially a new file descriptor, otherwise |
|
|
1032 | it is assumed that the file descriptor stays the same. That means that |
|
|
1033 | you I<have> to call C<ev_io_set> (or C<ev_io_init>) when you change the |
|
|
1034 | descriptor even if the file descriptor number itself did not change. |
|
|
1035 | |
|
|
1036 | This is how one would do it normally anyway, the important point is that |
|
|
1037 | the libev application should not optimise around libev but should leave |
|
|
1038 | optimisations to libev. |
|
|
1039 | |
|
|
1040 | =head3 The special problem of dup'ed file descriptors |
|
|
1041 | |
|
|
1042 | Some backends (e.g. epoll), cannot register events for file descriptors, |
|
|
1043 | but only events for the underlying file descriptions. That means when you |
|
|
1044 | have C<dup ()>'ed file descriptors or weirder constellations, and register |
|
|
1045 | events for them, only one file descriptor might actually receive events. |
|
|
1046 | |
|
|
1047 | There is no workaround possible except not registering events |
|
|
1048 | for potentially C<dup ()>'ed file descriptors, or to resort to |
|
|
1049 | C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>. |
|
|
1050 | |
|
|
1051 | =head3 The special problem of fork |
|
|
1052 | |
|
|
1053 | Some backends (epoll, kqueue) do not support C<fork ()> at all or exhibit |
|
|
1054 | useless behaviour. Libev fully supports fork, but needs to be told about |
|
|
1055 | it in the child. |
|
|
1056 | |
|
|
1057 | To support fork in your programs, you either have to call |
|
|
1058 | C<ev_default_fork ()> or C<ev_loop_fork ()> after a fork in the child, |
|
|
1059 | enable C<EVFLAG_FORKCHECK>, or resort to C<EVBACKEND_SELECT> or |
|
|
1060 | C<EVBACKEND_POLL>. |
|
|
1061 | |
|
|
1062 | |
|
|
1063 | =head3 Watcher-Specific Functions |
856 | |
1064 | |
857 | =over 4 |
1065 | =over 4 |
858 | |
1066 | |
859 | =item ev_io_init (ev_io *, callback, int fd, int events) |
1067 | =item ev_io_init (ev_io *, callback, int fd, int events) |
860 | |
1068 | |
… | |
… | |
871 | =item int events [read-only] |
1079 | =item int events [read-only] |
872 | |
1080 | |
873 | The events being watched. |
1081 | The events being watched. |
874 | |
1082 | |
875 | =back |
1083 | =back |
|
|
1084 | |
|
|
1085 | =head3 Examples |
876 | |
1086 | |
877 | Example: Call C<stdin_readable_cb> when STDIN_FILENO has become, well |
1087 | Example: Call C<stdin_readable_cb> when STDIN_FILENO has become, well |
878 | readable, but only once. Since it is likely line-buffered, you could |
1088 | readable, but only once. Since it is likely line-buffered, you could |
879 | attempt to read a whole line in the callback. |
1089 | attempt to read a whole line in the callback. |
880 | |
1090 | |
… | |
… | |
913 | ev_timer_set (&timer, after + ev_now () - ev_time (), 0.); |
1123 | ev_timer_set (&timer, after + ev_now () - ev_time (), 0.); |
914 | |
1124 | |
915 | The callback is guarenteed to be invoked only when its timeout has passed, |
1125 | The callback is guarenteed to be invoked only when its timeout has passed, |
916 | but if multiple timers become ready during the same loop iteration then |
1126 | but if multiple timers become ready during the same loop iteration then |
917 | order of execution is undefined. |
1127 | order of execution is undefined. |
|
|
1128 | |
|
|
1129 | =head3 Watcher-Specific Functions and Data Members |
918 | |
1130 | |
919 | =over 4 |
1131 | =over 4 |
920 | |
1132 | |
921 | =item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat) |
1133 | =item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat) |
922 | |
1134 | |
… | |
… | |
976 | or C<ev_timer_again> is called and determines the next timeout (if any), |
1188 | or C<ev_timer_again> is called and determines the next timeout (if any), |
977 | which is also when any modifications are taken into account. |
1189 | which is also when any modifications are taken into account. |
978 | |
1190 | |
979 | =back |
1191 | =back |
980 | |
1192 | |
|
|
1193 | =head3 Examples |
|
|
1194 | |
981 | Example: Create a timer that fires after 60 seconds. |
1195 | Example: Create a timer that fires after 60 seconds. |
982 | |
1196 | |
983 | static void |
1197 | static void |
984 | one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
1198 | one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
985 | { |
1199 | { |
… | |
… | |
1018 | but on wallclock time (absolute time). You can tell a periodic watcher |
1232 | but on wallclock time (absolute time). You can tell a periodic watcher |
1019 | to trigger "at" some specific point in time. For example, if you tell a |
1233 | to trigger "at" some specific point in time. For example, if you tell a |
1020 | periodic watcher to trigger in 10 seconds (by specifiying e.g. C<ev_now () |
1234 | periodic watcher to trigger in 10 seconds (by specifiying e.g. C<ev_now () |
1021 | + 10.>) and then reset your system clock to the last year, then it will |
1235 | + 10.>) and then reset your system clock to the last year, then it will |
1022 | take a year to trigger the event (unlike an C<ev_timer>, which would trigger |
1236 | take a year to trigger the event (unlike an C<ev_timer>, which would trigger |
1023 | roughly 10 seconds later and of course not if you reset your system time |
1237 | roughly 10 seconds later). |
1024 | again). |
|
|
1025 | |
1238 | |
1026 | They can also be used to implement vastly more complex timers, such as |
1239 | They can also be used to implement vastly more complex timers, such as |
1027 | triggering an event on eahc midnight, local time. |
1240 | triggering an event on each midnight, local time or other, complicated, |
|
|
1241 | rules. |
1028 | |
1242 | |
1029 | As with timers, the callback is guarenteed to be invoked only when the |
1243 | As with timers, the callback is guarenteed to be invoked only when the |
1030 | time (C<at>) has been passed, but if multiple periodic timers become ready |
1244 | time (C<at>) has been passed, but if multiple periodic timers become ready |
1031 | during the same loop iteration then order of execution is undefined. |
1245 | during the same loop iteration then order of execution is undefined. |
1032 | |
1246 | |
|
|
1247 | =head3 Watcher-Specific Functions and Data Members |
|
|
1248 | |
1033 | =over 4 |
1249 | =over 4 |
1034 | |
1250 | |
1035 | =item ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb) |
1251 | =item ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb) |
1036 | |
1252 | |
1037 | =item ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb) |
1253 | =item ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb) |
… | |
… | |
1039 | Lots of arguments, lets sort it out... There are basically three modes of |
1255 | Lots of arguments, lets sort it out... There are basically three modes of |
1040 | operation, and we will explain them from simplest to complex: |
1256 | operation, and we will explain them from simplest to complex: |
1041 | |
1257 | |
1042 | =over 4 |
1258 | =over 4 |
1043 | |
1259 | |
1044 | =item * absolute timer (interval = reschedule_cb = 0) |
1260 | =item * absolute timer (at = time, interval = reschedule_cb = 0) |
1045 | |
1261 | |
1046 | In this configuration the watcher triggers an event at the wallclock time |
1262 | In this configuration the watcher triggers an event at the wallclock time |
1047 | C<at> and doesn't repeat. It will not adjust when a time jump occurs, |
1263 | C<at> and doesn't repeat. It will not adjust when a time jump occurs, |
1048 | that is, if it is to be run at January 1st 2011 then it will run when the |
1264 | that is, if it is to be run at January 1st 2011 then it will run when the |
1049 | system time reaches or surpasses this time. |
1265 | system time reaches or surpasses this time. |
1050 | |
1266 | |
1051 | =item * non-repeating interval timer (interval > 0, reschedule_cb = 0) |
1267 | =item * non-repeating interval timer (at = offset, interval > 0, reschedule_cb = 0) |
1052 | |
1268 | |
1053 | In this mode the watcher will always be scheduled to time out at the next |
1269 | In this mode the watcher will always be scheduled to time out at the next |
1054 | C<at + N * interval> time (for some integer N) and then repeat, regardless |
1270 | C<at + N * interval> time (for some integer N, which can also be negative) |
1055 | of any time jumps. |
1271 | and then repeat, regardless of any time jumps. |
1056 | |
1272 | |
1057 | This can be used to create timers that do not drift with respect to system |
1273 | This can be used to create timers that do not drift with respect to system |
1058 | time: |
1274 | time: |
1059 | |
1275 | |
1060 | ev_periodic_set (&periodic, 0., 3600., 0); |
1276 | ev_periodic_set (&periodic, 0., 3600., 0); |
… | |
… | |
1066 | |
1282 | |
1067 | Another way to think about it (for the mathematically inclined) is that |
1283 | Another way to think about it (for the mathematically inclined) is that |
1068 | C<ev_periodic> will try to run the callback in this mode at the next possible |
1284 | C<ev_periodic> will try to run the callback in this mode at the next possible |
1069 | time where C<time = at (mod interval)>, regardless of any time jumps. |
1285 | time where C<time = at (mod interval)>, regardless of any time jumps. |
1070 | |
1286 | |
|
|
1287 | For numerical stability it is preferable that the C<at> value is near |
|
|
1288 | C<ev_now ()> (the current time), but there is no range requirement for |
|
|
1289 | this value. |
|
|
1290 | |
1071 | =item * manual reschedule mode (reschedule_cb = callback) |
1291 | =item * manual reschedule mode (at and interval ignored, reschedule_cb = callback) |
1072 | |
1292 | |
1073 | In this mode the values for C<interval> and C<at> are both being |
1293 | In this mode the values for C<interval> and C<at> are both being |
1074 | ignored. Instead, each time the periodic watcher gets scheduled, the |
1294 | ignored. Instead, each time the periodic watcher gets scheduled, the |
1075 | reschedule callback will be called with the watcher as first, and the |
1295 | reschedule callback will be called with the watcher as first, and the |
1076 | current time as second argument. |
1296 | current time as second argument. |
1077 | |
1297 | |
1078 | NOTE: I<This callback MUST NOT stop or destroy any periodic watcher, |
1298 | NOTE: I<This callback MUST NOT stop or destroy any periodic watcher, |
1079 | ever, or make any event loop modifications>. If you need to stop it, |
1299 | ever, or make any event loop modifications>. If you need to stop it, |
1080 | return C<now + 1e30> (or so, fudge fudge) and stop it afterwards (e.g. by |
1300 | return C<now + 1e30> (or so, fudge fudge) and stop it afterwards (e.g. by |
1081 | starting a prepare watcher). |
1301 | starting an C<ev_prepare> watcher, which is legal). |
1082 | |
1302 | |
1083 | Its prototype is C<ev_tstamp (*reschedule_cb)(struct ev_periodic *w, |
1303 | Its prototype is C<ev_tstamp (*reschedule_cb)(struct ev_periodic *w, |
1084 | ev_tstamp now)>, e.g.: |
1304 | ev_tstamp now)>, e.g.: |
1085 | |
1305 | |
1086 | static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now) |
1306 | static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now) |
… | |
… | |
1109 | Simply stops and restarts the periodic watcher again. This is only useful |
1329 | Simply stops and restarts the periodic watcher again. This is only useful |
1110 | when you changed some parameters or the reschedule callback would return |
1330 | when you changed some parameters or the reschedule callback would return |
1111 | a different time than the last time it was called (e.g. in a crond like |
1331 | a different time than the last time it was called (e.g. in a crond like |
1112 | program when the crontabs have changed). |
1332 | program when the crontabs have changed). |
1113 | |
1333 | |
|
|
1334 | =item ev_tstamp offset [read-write] |
|
|
1335 | |
|
|
1336 | When repeating, this contains the offset value, otherwise this is the |
|
|
1337 | absolute point in time (the C<at> value passed to C<ev_periodic_set>). |
|
|
1338 | |
|
|
1339 | Can be modified any time, but changes only take effect when the periodic |
|
|
1340 | timer fires or C<ev_periodic_again> is being called. |
|
|
1341 | |
1114 | =item ev_tstamp interval [read-write] |
1342 | =item ev_tstamp interval [read-write] |
1115 | |
1343 | |
1116 | The current interval value. Can be modified any time, but changes only |
1344 | The current interval value. Can be modified any time, but changes only |
1117 | take effect when the periodic timer fires or C<ev_periodic_again> is being |
1345 | take effect when the periodic timer fires or C<ev_periodic_again> is being |
1118 | called. |
1346 | called. |
… | |
… | |
1121 | |
1349 | |
1122 | The current reschedule callback, or C<0>, if this functionality is |
1350 | The current reschedule callback, or C<0>, if this functionality is |
1123 | switched off. Can be changed any time, but changes only take effect when |
1351 | switched off. Can be changed any time, but changes only take effect when |
1124 | the periodic timer fires or C<ev_periodic_again> is being called. |
1352 | the periodic timer fires or C<ev_periodic_again> is being called. |
1125 | |
1353 | |
|
|
1354 | =item ev_tstamp at [read-only] |
|
|
1355 | |
|
|
1356 | When active, contains the absolute time that the watcher is supposed to |
|
|
1357 | trigger next. |
|
|
1358 | |
1126 | =back |
1359 | =back |
|
|
1360 | |
|
|
1361 | =head3 Examples |
1127 | |
1362 | |
1128 | Example: Call a callback every hour, or, more precisely, whenever the |
1363 | Example: Call a callback every hour, or, more precisely, whenever the |
1129 | system clock is divisible by 3600. The callback invocation times have |
1364 | system clock is divisible by 3600. The callback invocation times have |
1130 | potentially a lot of jittering, but good long-term stability. |
1365 | potentially a lot of jittering, but good long-term stability. |
1131 | |
1366 | |
… | |
… | |
1171 | with the kernel (thus it coexists with your own signal handlers as long |
1406 | with the kernel (thus it coexists with your own signal handlers as long |
1172 | as you don't register any with libev). Similarly, when the last signal |
1407 | as you don't register any with libev). Similarly, when the last signal |
1173 | watcher for a signal is stopped libev will reset the signal handler to |
1408 | watcher for a signal is stopped libev will reset the signal handler to |
1174 | SIG_DFL (regardless of what it was set to before). |
1409 | SIG_DFL (regardless of what it was set to before). |
1175 | |
1410 | |
|
|
1411 | =head3 Watcher-Specific Functions and Data Members |
|
|
1412 | |
1176 | =over 4 |
1413 | =over 4 |
1177 | |
1414 | |
1178 | =item ev_signal_init (ev_signal *, callback, int signum) |
1415 | =item ev_signal_init (ev_signal *, callback, int signum) |
1179 | |
1416 | |
1180 | =item ev_signal_set (ev_signal *, int signum) |
1417 | =item ev_signal_set (ev_signal *, int signum) |
… | |
… | |
1191 | |
1428 | |
1192 | =head2 C<ev_child> - watch out for process status changes |
1429 | =head2 C<ev_child> - watch out for process status changes |
1193 | |
1430 | |
1194 | Child watchers trigger when your process receives a SIGCHLD in response to |
1431 | Child watchers trigger when your process receives a SIGCHLD in response to |
1195 | some child status changes (most typically when a child of yours dies). |
1432 | some child status changes (most typically when a child of yours dies). |
|
|
1433 | |
|
|
1434 | =head3 Watcher-Specific Functions and Data Members |
1196 | |
1435 | |
1197 | =over 4 |
1436 | =over 4 |
1198 | |
1437 | |
1199 | =item ev_child_init (ev_child *, callback, int pid) |
1438 | =item ev_child_init (ev_child *, callback, int pid) |
1200 | |
1439 | |
… | |
… | |
1219 | |
1458 | |
1220 | The process exit/trace status caused by C<rpid> (see your systems |
1459 | The process exit/trace status caused by C<rpid> (see your systems |
1221 | C<waitpid> and C<sys/wait.h> documentation for details). |
1460 | C<waitpid> and C<sys/wait.h> documentation for details). |
1222 | |
1461 | |
1223 | =back |
1462 | =back |
|
|
1463 | |
|
|
1464 | =head3 Examples |
1224 | |
1465 | |
1225 | Example: Try to exit cleanly on SIGINT and SIGTERM. |
1466 | Example: Try to exit cleanly on SIGINT and SIGTERM. |
1226 | |
1467 | |
1227 | static void |
1468 | static void |
1228 | sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) |
1469 | sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) |
… | |
… | |
1269 | semantics of C<ev_stat> watchers, which means that libev sometimes needs |
1510 | semantics of C<ev_stat> watchers, which means that libev sometimes needs |
1270 | to fall back to regular polling again even with inotify, but changes are |
1511 | to fall back to regular polling again even with inotify, but changes are |
1271 | usually detected immediately, and if the file exists there will be no |
1512 | usually detected immediately, and if the file exists there will be no |
1272 | polling. |
1513 | polling. |
1273 | |
1514 | |
|
|
1515 | =head3 Inotify |
|
|
1516 | |
|
|
1517 | When C<inotify (7)> support has been compiled into libev (generally only |
|
|
1518 | available on Linux) and present at runtime, it will be used to speed up |
|
|
1519 | change detection where possible. The inotify descriptor will be created lazily |
|
|
1520 | when the first C<ev_stat> watcher is being started. |
|
|
1521 | |
|
|
1522 | Inotify presense does not change the semantics of C<ev_stat> watchers |
|
|
1523 | except that changes might be detected earlier, and in some cases, to avoid |
|
|
1524 | making regular C<stat> calls. Even in the presense of inotify support |
|
|
1525 | there are many cases where libev has to resort to regular C<stat> polling. |
|
|
1526 | |
|
|
1527 | (There is no support for kqueue, as apparently it cannot be used to |
|
|
1528 | implement this functionality, due to the requirement of having a file |
|
|
1529 | descriptor open on the object at all times). |
|
|
1530 | |
|
|
1531 | =head3 The special problem of stat time resolution |
|
|
1532 | |
|
|
1533 | The C<stat ()> syscall only supports full-second resolution portably, and |
|
|
1534 | even on systems where the resolution is higher, many filesystems still |
|
|
1535 | only support whole seconds. |
|
|
1536 | |
|
|
1537 | That means that, if the time is the only thing that changes, you might |
|
|
1538 | miss updates: on the first update, C<ev_stat> detects a change and calls |
|
|
1539 | your callback, which does something. When there is another update within |
|
|
1540 | the same second, C<ev_stat> will be unable to detect it. |
|
|
1541 | |
|
|
1542 | The solution to this is to delay acting on a change for a second (or till |
|
|
1543 | the next second boundary), using a roughly one-second delay C<ev_timer> |
|
|
1544 | (C<ev_timer_set (w, 0., 1.01); ev_timer_again (loop, w)>). The C<.01> |
|
|
1545 | is added to work around small timing inconsistencies of some operating |
|
|
1546 | systems. |
|
|
1547 | |
|
|
1548 | =head3 Watcher-Specific Functions and Data Members |
|
|
1549 | |
1274 | =over 4 |
1550 | =over 4 |
1275 | |
1551 | |
1276 | =item ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval) |
1552 | =item ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval) |
1277 | |
1553 | |
1278 | =item ev_stat_set (ev_stat *, const char *path, ev_tstamp interval) |
1554 | =item ev_stat_set (ev_stat *, const char *path, ev_tstamp interval) |
… | |
… | |
1313 | =item const char *path [read-only] |
1589 | =item const char *path [read-only] |
1314 | |
1590 | |
1315 | The filesystem path that is being watched. |
1591 | The filesystem path that is being watched. |
1316 | |
1592 | |
1317 | =back |
1593 | =back |
|
|
1594 | |
|
|
1595 | =head3 Examples |
1318 | |
1596 | |
1319 | Example: Watch C</etc/passwd> for attribute changes. |
1597 | Example: Watch C</etc/passwd> for attribute changes. |
1320 | |
1598 | |
1321 | static void |
1599 | static void |
1322 | passwd_cb (struct ev_loop *loop, ev_stat *w, int revents) |
1600 | passwd_cb (struct ev_loop *loop, ev_stat *w, int revents) |
… | |
… | |
1335 | } |
1613 | } |
1336 | |
1614 | |
1337 | ... |
1615 | ... |
1338 | ev_stat passwd; |
1616 | ev_stat passwd; |
1339 | |
1617 | |
1340 | ev_stat_init (&passwd, passwd_cb, "/etc/passwd"); |
1618 | ev_stat_init (&passwd, passwd_cb, "/etc/passwd", 0.); |
1341 | ev_stat_start (loop, &passwd); |
1619 | ev_stat_start (loop, &passwd); |
1342 | |
1620 | |
|
|
1621 | Example: Like above, but additionally use a one-second delay so we do not |
|
|
1622 | miss updates (however, frequent updates will delay processing, too, so |
|
|
1623 | one might do the work both on C<ev_stat> callback invocation I<and> on |
|
|
1624 | C<ev_timer> callback invocation). |
|
|
1625 | |
|
|
1626 | static ev_stat passwd; |
|
|
1627 | static ev_timer timer; |
|
|
1628 | |
|
|
1629 | static void |
|
|
1630 | timer_cb (EV_P_ ev_timer *w, int revents) |
|
|
1631 | { |
|
|
1632 | ev_timer_stop (EV_A_ w); |
|
|
1633 | |
|
|
1634 | /* now it's one second after the most recent passwd change */ |
|
|
1635 | } |
|
|
1636 | |
|
|
1637 | static void |
|
|
1638 | stat_cb (EV_P_ ev_stat *w, int revents) |
|
|
1639 | { |
|
|
1640 | /* reset the one-second timer */ |
|
|
1641 | ev_timer_again (EV_A_ &timer); |
|
|
1642 | } |
|
|
1643 | |
|
|
1644 | ... |
|
|
1645 | ev_stat_init (&passwd, stat_cb, "/etc/passwd", 0.); |
|
|
1646 | ev_stat_start (loop, &passwd); |
|
|
1647 | ev_timer_init (&timer, timer_cb, 0., 1.01); |
|
|
1648 | |
1343 | |
1649 | |
1344 | =head2 C<ev_idle> - when you've got nothing better to do... |
1650 | =head2 C<ev_idle> - when you've got nothing better to do... |
1345 | |
1651 | |
1346 | Idle watchers trigger events when there are no other events are pending |
1652 | Idle watchers trigger events when no other events of the same or higher |
1347 | (prepare, check and other idle watchers do not count). That is, as long |
1653 | priority are pending (prepare, check and other idle watchers do not |
1348 | as your process is busy handling sockets or timeouts (or even signals, |
1654 | count). |
1349 | imagine) it will not be triggered. But when your process is idle all idle |
1655 | |
1350 | watchers are being called again and again, once per event loop iteration - |
1656 | That is, as long as your process is busy handling sockets or timeouts |
|
|
1657 | (or even signals, imagine) of the same or higher priority it will not be |
|
|
1658 | triggered. But when your process is idle (or only lower-priority watchers |
|
|
1659 | are pending), the idle watchers are being called once per event loop |
1351 | until stopped, that is, or your process receives more events and becomes |
1660 | iteration - until stopped, that is, or your process receives more events |
1352 | busy. |
1661 | and becomes busy again with higher priority stuff. |
1353 | |
1662 | |
1354 | The most noteworthy effect is that as long as any idle watchers are |
1663 | The most noteworthy effect is that as long as any idle watchers are |
1355 | active, the process will not block when waiting for new events. |
1664 | active, the process will not block when waiting for new events. |
1356 | |
1665 | |
1357 | Apart from keeping your process non-blocking (which is a useful |
1666 | Apart from keeping your process non-blocking (which is a useful |
1358 | effect on its own sometimes), idle watchers are a good place to do |
1667 | effect on its own sometimes), idle watchers are a good place to do |
1359 | "pseudo-background processing", or delay processing stuff to after the |
1668 | "pseudo-background processing", or delay processing stuff to after the |
1360 | event loop has handled all outstanding events. |
1669 | event loop has handled all outstanding events. |
1361 | |
1670 | |
|
|
1671 | =head3 Watcher-Specific Functions and Data Members |
|
|
1672 | |
1362 | =over 4 |
1673 | =over 4 |
1363 | |
1674 | |
1364 | =item ev_idle_init (ev_signal *, callback) |
1675 | =item ev_idle_init (ev_signal *, callback) |
1365 | |
1676 | |
1366 | Initialises and configures the idle watcher - it has no parameters of any |
1677 | Initialises and configures the idle watcher - it has no parameters of any |
1367 | kind. There is a C<ev_idle_set> macro, but using it is utterly pointless, |
1678 | kind. There is a C<ev_idle_set> macro, but using it is utterly pointless, |
1368 | believe me. |
1679 | believe me. |
1369 | |
1680 | |
1370 | =back |
1681 | =back |
|
|
1682 | |
|
|
1683 | =head3 Examples |
1371 | |
1684 | |
1372 | Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the |
1685 | Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the |
1373 | callback, free it. Also, use no error checking, as usual. |
1686 | callback, free it. Also, use no error checking, as usual. |
1374 | |
1687 | |
1375 | static void |
1688 | static void |
… | |
… | |
1423 | with priority higher than or equal to the event loop and one coroutine |
1736 | with priority higher than or equal to the event loop and one coroutine |
1424 | of lower priority, but only once, using idle watchers to keep the event |
1737 | of lower priority, but only once, using idle watchers to keep the event |
1425 | loop from blocking if lower-priority coroutines are active, thus mapping |
1738 | loop from blocking if lower-priority coroutines are active, thus mapping |
1426 | low-priority coroutines to idle/background tasks). |
1739 | low-priority coroutines to idle/background tasks). |
1427 | |
1740 | |
|
|
1741 | It is recommended to give C<ev_check> watchers highest (C<EV_MAXPRI>) |
|
|
1742 | priority, to ensure that they are being run before any other watchers |
|
|
1743 | after the poll. Also, C<ev_check> watchers (and C<ev_prepare> watchers, |
|
|
1744 | too) should not activate ("feed") events into libev. While libev fully |
|
|
1745 | supports this, they will be called before other C<ev_check> watchers |
|
|
1746 | did their job. As C<ev_check> watchers are often used to embed other |
|
|
1747 | (non-libev) event loops those other event loops might be in an unusable |
|
|
1748 | state until their C<ev_check> watcher ran (always remind yourself to |
|
|
1749 | coexist peacefully with others). |
|
|
1750 | |
|
|
1751 | =head3 Watcher-Specific Functions and Data Members |
|
|
1752 | |
1428 | =over 4 |
1753 | =over 4 |
1429 | |
1754 | |
1430 | =item ev_prepare_init (ev_prepare *, callback) |
1755 | =item ev_prepare_init (ev_prepare *, callback) |
1431 | |
1756 | |
1432 | =item ev_check_init (ev_check *, callback) |
1757 | =item ev_check_init (ev_check *, callback) |
… | |
… | |
1435 | parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set> |
1760 | parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set> |
1436 | macros, but using them is utterly, utterly and completely pointless. |
1761 | macros, but using them is utterly, utterly and completely pointless. |
1437 | |
1762 | |
1438 | =back |
1763 | =back |
1439 | |
1764 | |
1440 | Example: To include a library such as adns, you would add IO watchers |
1765 | =head3 Examples |
1441 | and a timeout watcher in a prepare handler, as required by libadns, and |
1766 | |
|
|
1767 | There are a number of principal ways to embed other event loops or modules |
|
|
1768 | into libev. Here are some ideas on how to include libadns into libev |
|
|
1769 | (there is a Perl module named C<EV::ADNS> that does this, which you could |
|
|
1770 | use for an actually working example. Another Perl module named C<EV::Glib> |
|
|
1771 | embeds a Glib main context into libev, and finally, C<Glib::EV> embeds EV |
|
|
1772 | into the Glib event loop). |
|
|
1773 | |
|
|
1774 | Method 1: Add IO watchers and a timeout watcher in a prepare handler, |
1442 | in a check watcher, destroy them and call into libadns. What follows is |
1775 | and in a check watcher, destroy them and call into libadns. What follows |
1443 | pseudo-code only of course: |
1776 | is pseudo-code only of course. This requires you to either use a low |
|
|
1777 | priority for the check watcher or use C<ev_clear_pending> explicitly, as |
|
|
1778 | the callbacks for the IO/timeout watchers might not have been called yet. |
1444 | |
1779 | |
1445 | static ev_io iow [nfd]; |
1780 | static ev_io iow [nfd]; |
1446 | static ev_timer tw; |
1781 | static ev_timer tw; |
1447 | |
1782 | |
1448 | static void |
1783 | static void |
1449 | io_cb (ev_loop *loop, ev_io *w, int revents) |
1784 | io_cb (ev_loop *loop, ev_io *w, int revents) |
1450 | { |
1785 | { |
1451 | // set the relevant poll flags |
|
|
1452 | // could also call adns_processreadable etc. here |
|
|
1453 | struct pollfd *fd = (struct pollfd *)w->data; |
|
|
1454 | if (revents & EV_READ ) fd->revents |= fd->events & POLLIN; |
|
|
1455 | if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT; |
|
|
1456 | } |
1786 | } |
1457 | |
1787 | |
1458 | // create io watchers for each fd and a timer before blocking |
1788 | // create io watchers for each fd and a timer before blocking |
1459 | static void |
1789 | static void |
1460 | adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) |
1790 | adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) |
1461 | { |
1791 | { |
1462 | int timeout = 3600000;truct pollfd fds [nfd]; |
1792 | int timeout = 3600000; |
|
|
1793 | struct pollfd fds [nfd]; |
1463 | // actual code will need to loop here and realloc etc. |
1794 | // actual code will need to loop here and realloc etc. |
1464 | adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
1795 | adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
1465 | |
1796 | |
1466 | /* the callback is illegal, but won't be called as we stop during check */ |
1797 | /* the callback is illegal, but won't be called as we stop during check */ |
1467 | ev_timer_init (&tw, 0, timeout * 1e-3); |
1798 | ev_timer_init (&tw, 0, timeout * 1e-3); |
1468 | ev_timer_start (loop, &tw); |
1799 | ev_timer_start (loop, &tw); |
1469 | |
1800 | |
1470 | // create on ev_io per pollfd |
1801 | // create one ev_io per pollfd |
1471 | for (int i = 0; i < nfd; ++i) |
1802 | for (int i = 0; i < nfd; ++i) |
1472 | { |
1803 | { |
1473 | ev_io_init (iow + i, io_cb, fds [i].fd, |
1804 | ev_io_init (iow + i, io_cb, fds [i].fd, |
1474 | ((fds [i].events & POLLIN ? EV_READ : 0) |
1805 | ((fds [i].events & POLLIN ? EV_READ : 0) |
1475 | | (fds [i].events & POLLOUT ? EV_WRITE : 0))); |
1806 | | (fds [i].events & POLLOUT ? EV_WRITE : 0))); |
1476 | |
1807 | |
1477 | fds [i].revents = 0; |
1808 | fds [i].revents = 0; |
1478 | iow [i].data = fds + i; |
|
|
1479 | ev_io_start (loop, iow + i); |
1809 | ev_io_start (loop, iow + i); |
1480 | } |
1810 | } |
1481 | } |
1811 | } |
1482 | |
1812 | |
1483 | // stop all watchers after blocking |
1813 | // stop all watchers after blocking |
… | |
… | |
1485 | adns_check_cb (ev_loop *loop, ev_check *w, int revents) |
1815 | adns_check_cb (ev_loop *loop, ev_check *w, int revents) |
1486 | { |
1816 | { |
1487 | ev_timer_stop (loop, &tw); |
1817 | ev_timer_stop (loop, &tw); |
1488 | |
1818 | |
1489 | for (int i = 0; i < nfd; ++i) |
1819 | for (int i = 0; i < nfd; ++i) |
|
|
1820 | { |
|
|
1821 | // set the relevant poll flags |
|
|
1822 | // could also call adns_processreadable etc. here |
|
|
1823 | struct pollfd *fd = fds + i; |
|
|
1824 | int revents = ev_clear_pending (iow + i); |
|
|
1825 | if (revents & EV_READ ) fd->revents |= fd->events & POLLIN; |
|
|
1826 | if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT; |
|
|
1827 | |
|
|
1828 | // now stop the watcher |
1490 | ev_io_stop (loop, iow + i); |
1829 | ev_io_stop (loop, iow + i); |
|
|
1830 | } |
1491 | |
1831 | |
1492 | adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop)); |
1832 | adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop)); |
|
|
1833 | } |
|
|
1834 | |
|
|
1835 | Method 2: This would be just like method 1, but you run C<adns_afterpoll> |
|
|
1836 | in the prepare watcher and would dispose of the check watcher. |
|
|
1837 | |
|
|
1838 | Method 3: If the module to be embedded supports explicit event |
|
|
1839 | notification (adns does), you can also make use of the actual watcher |
|
|
1840 | callbacks, and only destroy/create the watchers in the prepare watcher. |
|
|
1841 | |
|
|
1842 | static void |
|
|
1843 | timer_cb (EV_P_ ev_timer *w, int revents) |
|
|
1844 | { |
|
|
1845 | adns_state ads = (adns_state)w->data; |
|
|
1846 | update_now (EV_A); |
|
|
1847 | |
|
|
1848 | adns_processtimeouts (ads, &tv_now); |
|
|
1849 | } |
|
|
1850 | |
|
|
1851 | static void |
|
|
1852 | io_cb (EV_P_ ev_io *w, int revents) |
|
|
1853 | { |
|
|
1854 | adns_state ads = (adns_state)w->data; |
|
|
1855 | update_now (EV_A); |
|
|
1856 | |
|
|
1857 | if (revents & EV_READ ) adns_processreadable (ads, w->fd, &tv_now); |
|
|
1858 | if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now); |
|
|
1859 | } |
|
|
1860 | |
|
|
1861 | // do not ever call adns_afterpoll |
|
|
1862 | |
|
|
1863 | Method 4: Do not use a prepare or check watcher because the module you |
|
|
1864 | want to embed is too inflexible to support it. Instead, youc na override |
|
|
1865 | their poll function. The drawback with this solution is that the main |
|
|
1866 | loop is now no longer controllable by EV. The C<Glib::EV> module does |
|
|
1867 | this. |
|
|
1868 | |
|
|
1869 | static gint |
|
|
1870 | event_poll_func (GPollFD *fds, guint nfds, gint timeout) |
|
|
1871 | { |
|
|
1872 | int got_events = 0; |
|
|
1873 | |
|
|
1874 | for (n = 0; n < nfds; ++n) |
|
|
1875 | // create/start io watcher that sets the relevant bits in fds[n] and increment got_events |
|
|
1876 | |
|
|
1877 | if (timeout >= 0) |
|
|
1878 | // create/start timer |
|
|
1879 | |
|
|
1880 | // poll |
|
|
1881 | ev_loop (EV_A_ 0); |
|
|
1882 | |
|
|
1883 | // stop timer again |
|
|
1884 | if (timeout >= 0) |
|
|
1885 | ev_timer_stop (EV_A_ &to); |
|
|
1886 | |
|
|
1887 | // stop io watchers again - their callbacks should have set |
|
|
1888 | for (n = 0; n < nfds; ++n) |
|
|
1889 | ev_io_stop (EV_A_ iow [n]); |
|
|
1890 | |
|
|
1891 | return got_events; |
1493 | } |
1892 | } |
1494 | |
1893 | |
1495 | |
1894 | |
1496 | =head2 C<ev_embed> - when one backend isn't enough... |
1895 | =head2 C<ev_embed> - when one backend isn't enough... |
1497 | |
1896 | |
… | |
… | |
1540 | portable one. |
1939 | portable one. |
1541 | |
1940 | |
1542 | So when you want to use this feature you will always have to be prepared |
1941 | So when you want to use this feature you will always have to be prepared |
1543 | that you cannot get an embeddable loop. The recommended way to get around |
1942 | that you cannot get an embeddable loop. The recommended way to get around |
1544 | this is to have a separate variables for your embeddable loop, try to |
1943 | this is to have a separate variables for your embeddable loop, try to |
1545 | create it, and if that fails, use the normal loop for everything: |
1944 | create it, and if that fails, use the normal loop for everything. |
|
|
1945 | |
|
|
1946 | =head3 Watcher-Specific Functions and Data Members |
|
|
1947 | |
|
|
1948 | =over 4 |
|
|
1949 | |
|
|
1950 | =item ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop) |
|
|
1951 | |
|
|
1952 | =item ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop) |
|
|
1953 | |
|
|
1954 | Configures the watcher to embed the given loop, which must be |
|
|
1955 | embeddable. If the callback is C<0>, then C<ev_embed_sweep> will be |
|
|
1956 | invoked automatically, otherwise it is the responsibility of the callback |
|
|
1957 | to invoke it (it will continue to be called until the sweep has been done, |
|
|
1958 | if you do not want thta, you need to temporarily stop the embed watcher). |
|
|
1959 | |
|
|
1960 | =item ev_embed_sweep (loop, ev_embed *) |
|
|
1961 | |
|
|
1962 | Make a single, non-blocking sweep over the embedded loop. This works |
|
|
1963 | similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most |
|
|
1964 | apropriate way for embedded loops. |
|
|
1965 | |
|
|
1966 | =item struct ev_loop *other [read-only] |
|
|
1967 | |
|
|
1968 | The embedded event loop. |
|
|
1969 | |
|
|
1970 | =back |
|
|
1971 | |
|
|
1972 | =head3 Examples |
|
|
1973 | |
|
|
1974 | Example: Try to get an embeddable event loop and embed it into the default |
|
|
1975 | event loop. If that is not possible, use the default loop. The default |
|
|
1976 | loop is stored in C<loop_hi>, while the mebeddable loop is stored in |
|
|
1977 | C<loop_lo> (which is C<loop_hi> in the acse no embeddable loop can be |
|
|
1978 | used). |
1546 | |
1979 | |
1547 | struct ev_loop *loop_hi = ev_default_init (0); |
1980 | struct ev_loop *loop_hi = ev_default_init (0); |
1548 | struct ev_loop *loop_lo = 0; |
1981 | struct ev_loop *loop_lo = 0; |
1549 | struct ev_embed embed; |
1982 | struct ev_embed embed; |
1550 | |
1983 | |
… | |
… | |
1561 | ev_embed_start (loop_hi, &embed); |
1994 | ev_embed_start (loop_hi, &embed); |
1562 | } |
1995 | } |
1563 | else |
1996 | else |
1564 | loop_lo = loop_hi; |
1997 | loop_lo = loop_hi; |
1565 | |
1998 | |
1566 | =over 4 |
1999 | Example: Check if kqueue is available but not recommended and create |
|
|
2000 | a kqueue backend for use with sockets (which usually work with any |
|
|
2001 | kqueue implementation). Store the kqueue/socket-only event loop in |
|
|
2002 | C<loop_socket>. (One might optionally use C<EVFLAG_NOENV>, too). |
1567 | |
2003 | |
1568 | =item ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop) |
2004 | struct ev_loop *loop = ev_default_init (0); |
|
|
2005 | struct ev_loop *loop_socket = 0; |
|
|
2006 | struct ev_embed embed; |
|
|
2007 | |
|
|
2008 | if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE) |
|
|
2009 | if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE)) |
|
|
2010 | { |
|
|
2011 | ev_embed_init (&embed, 0, loop_socket); |
|
|
2012 | ev_embed_start (loop, &embed); |
|
|
2013 | } |
1569 | |
2014 | |
1570 | =item ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop) |
2015 | if (!loop_socket) |
|
|
2016 | loop_socket = loop; |
1571 | |
2017 | |
1572 | Configures the watcher to embed the given loop, which must be |
2018 | // now use loop_socket for all sockets, and loop for everything else |
1573 | embeddable. If the callback is C<0>, then C<ev_embed_sweep> will be |
|
|
1574 | invoked automatically, otherwise it is the responsibility of the callback |
|
|
1575 | to invoke it (it will continue to be called until the sweep has been done, |
|
|
1576 | if you do not want thta, you need to temporarily stop the embed watcher). |
|
|
1577 | |
|
|
1578 | =item ev_embed_sweep (loop, ev_embed *) |
|
|
1579 | |
|
|
1580 | Make a single, non-blocking sweep over the embedded loop. This works |
|
|
1581 | similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most |
|
|
1582 | apropriate way for embedded loops. |
|
|
1583 | |
|
|
1584 | =item struct ev_loop *loop [read-only] |
|
|
1585 | |
|
|
1586 | The embedded event loop. |
|
|
1587 | |
|
|
1588 | =back |
|
|
1589 | |
2019 | |
1590 | |
2020 | |
1591 | =head2 C<ev_fork> - the audacity to resume the event loop after a fork |
2021 | =head2 C<ev_fork> - the audacity to resume the event loop after a fork |
1592 | |
2022 | |
1593 | Fork watchers are called when a C<fork ()> was detected (usually because |
2023 | Fork watchers are called when a C<fork ()> was detected (usually because |
… | |
… | |
1596 | event loop blocks next and before C<ev_check> watchers are being called, |
2026 | event loop blocks next and before C<ev_check> watchers are being called, |
1597 | and only in the child after the fork. If whoever good citizen calling |
2027 | and only in the child after the fork. If whoever good citizen calling |
1598 | C<ev_default_fork> cheats and calls it in the wrong process, the fork |
2028 | C<ev_default_fork> cheats and calls it in the wrong process, the fork |
1599 | handlers will be invoked, too, of course. |
2029 | handlers will be invoked, too, of course. |
1600 | |
2030 | |
|
|
2031 | =head3 Watcher-Specific Functions and Data Members |
|
|
2032 | |
1601 | =over 4 |
2033 | =over 4 |
1602 | |
2034 | |
1603 | =item ev_fork_init (ev_signal *, callback) |
2035 | =item ev_fork_init (ev_signal *, callback) |
1604 | |
2036 | |
1605 | Initialises and configures the fork watcher - it has no parameters of any |
2037 | Initialises and configures the fork watcher - it has no parameters of any |
… | |
… | |
1701 | |
2133 | |
1702 | To use it, |
2134 | To use it, |
1703 | |
2135 | |
1704 | #include <ev++.h> |
2136 | #include <ev++.h> |
1705 | |
2137 | |
1706 | (it is not installed by default). This automatically includes F<ev.h> |
2138 | This automatically includes F<ev.h> and puts all of its definitions (many |
1707 | and puts all of its definitions (many of them macros) into the global |
2139 | of them macros) into the global namespace. All C++ specific things are |
1708 | namespace. All C++ specific things are put into the C<ev> namespace. |
2140 | put into the C<ev> namespace. It should support all the same embedding |
|
|
2141 | options as F<ev.h>, most notably C<EV_MULTIPLICITY>. |
1709 | |
2142 | |
1710 | It should support all the same embedding options as F<ev.h>, most notably |
2143 | Care has been taken to keep the overhead low. The only data member the C++ |
1711 | C<EV_MULTIPLICITY>. |
2144 | classes add (compared to plain C-style watchers) is the event loop pointer |
|
|
2145 | that the watcher is associated with (or no additional members at all if |
|
|
2146 | you disable C<EV_MULTIPLICITY> when embedding libev). |
|
|
2147 | |
|
|
2148 | Currently, functions, and static and non-static member functions can be |
|
|
2149 | used as callbacks. Other types should be easy to add as long as they only |
|
|
2150 | need one additional pointer for context. If you need support for other |
|
|
2151 | types of functors please contact the author (preferably after implementing |
|
|
2152 | it). |
1712 | |
2153 | |
1713 | Here is a list of things available in the C<ev> namespace: |
2154 | Here is a list of things available in the C<ev> namespace: |
1714 | |
2155 | |
1715 | =over 4 |
2156 | =over 4 |
1716 | |
2157 | |
… | |
… | |
1732 | |
2173 | |
1733 | All of those classes have these methods: |
2174 | All of those classes have these methods: |
1734 | |
2175 | |
1735 | =over 4 |
2176 | =over 4 |
1736 | |
2177 | |
1737 | =item ev::TYPE::TYPE (object *, object::method *) |
2178 | =item ev::TYPE::TYPE () |
1738 | |
2179 | |
1739 | =item ev::TYPE::TYPE (object *, object::method *, struct ev_loop *) |
2180 | =item ev::TYPE::TYPE (struct ev_loop *) |
1740 | |
2181 | |
1741 | =item ev::TYPE::~TYPE |
2182 | =item ev::TYPE::~TYPE |
1742 | |
2183 | |
1743 | The constructor takes a pointer to an object and a method pointer to |
2184 | The constructor (optionally) takes an event loop to associate the watcher |
1744 | the event handler callback to call in this class. The constructor calls |
2185 | with. If it is omitted, it will use C<EV_DEFAULT>. |
1745 | C<ev_init> for you, which means you have to call the C<set> method |
2186 | |
1746 | before starting it. If you do not specify a loop then the constructor |
2187 | The constructor calls C<ev_init> for you, which means you have to call the |
1747 | automatically associates the default loop with this watcher. |
2188 | C<set> method before starting it. |
|
|
2189 | |
|
|
2190 | It will not set a callback, however: You have to call the templated C<set> |
|
|
2191 | method to set a callback before you can start the watcher. |
|
|
2192 | |
|
|
2193 | (The reason why you have to use a method is a limitation in C++ which does |
|
|
2194 | not allow explicit template arguments for constructors). |
1748 | |
2195 | |
1749 | The destructor automatically stops the watcher if it is active. |
2196 | The destructor automatically stops the watcher if it is active. |
|
|
2197 | |
|
|
2198 | =item w->set<class, &class::method> (object *) |
|
|
2199 | |
|
|
2200 | This method sets the callback method to call. The method has to have a |
|
|
2201 | signature of C<void (*)(ev_TYPE &, int)>, it receives the watcher as |
|
|
2202 | first argument and the C<revents> as second. The object must be given as |
|
|
2203 | parameter and is stored in the C<data> member of the watcher. |
|
|
2204 | |
|
|
2205 | This method synthesizes efficient thunking code to call your method from |
|
|
2206 | the C callback that libev requires. If your compiler can inline your |
|
|
2207 | callback (i.e. it is visible to it at the place of the C<set> call and |
|
|
2208 | your compiler is good :), then the method will be fully inlined into the |
|
|
2209 | thunking function, making it as fast as a direct C callback. |
|
|
2210 | |
|
|
2211 | Example: simple class declaration and watcher initialisation |
|
|
2212 | |
|
|
2213 | struct myclass |
|
|
2214 | { |
|
|
2215 | void io_cb (ev::io &w, int revents) { } |
|
|
2216 | } |
|
|
2217 | |
|
|
2218 | myclass obj; |
|
|
2219 | ev::io iow; |
|
|
2220 | iow.set <myclass, &myclass::io_cb> (&obj); |
|
|
2221 | |
|
|
2222 | =item w->set<function> (void *data = 0) |
|
|
2223 | |
|
|
2224 | Also sets a callback, but uses a static method or plain function as |
|
|
2225 | callback. The optional C<data> argument will be stored in the watcher's |
|
|
2226 | C<data> member and is free for you to use. |
|
|
2227 | |
|
|
2228 | The prototype of the C<function> must be C<void (*)(ev::TYPE &w, int)>. |
|
|
2229 | |
|
|
2230 | See the method-C<set> above for more details. |
|
|
2231 | |
|
|
2232 | Example: |
|
|
2233 | |
|
|
2234 | static void io_cb (ev::io &w, int revents) { } |
|
|
2235 | iow.set <io_cb> (); |
1750 | |
2236 | |
1751 | =item w->set (struct ev_loop *) |
2237 | =item w->set (struct ev_loop *) |
1752 | |
2238 | |
1753 | Associates a different C<struct ev_loop> with this watcher. You can only |
2239 | Associates a different C<struct ev_loop> with this watcher. You can only |
1754 | do this when the watcher is inactive (and not pending either). |
2240 | do this when the watcher is inactive (and not pending either). |
1755 | |
2241 | |
1756 | =item w->set ([args]) |
2242 | =item w->set ([args]) |
1757 | |
2243 | |
1758 | Basically the same as C<ev_TYPE_set>, with the same args. Must be |
2244 | Basically the same as C<ev_TYPE_set>, with the same args. Must be |
1759 | called at least once. Unlike the C counterpart, an active watcher gets |
2245 | called at least once. Unlike the C counterpart, an active watcher gets |
1760 | automatically stopped and restarted. |
2246 | automatically stopped and restarted when reconfiguring it with this |
|
|
2247 | method. |
1761 | |
2248 | |
1762 | =item w->start () |
2249 | =item w->start () |
1763 | |
2250 | |
1764 | Starts the watcher. Note that there is no C<loop> argument as the |
2251 | Starts the watcher. Note that there is no C<loop> argument, as the |
1765 | constructor already takes the loop. |
2252 | constructor already stores the event loop. |
1766 | |
2253 | |
1767 | =item w->stop () |
2254 | =item w->stop () |
1768 | |
2255 | |
1769 | Stops the watcher if it is active. Again, no C<loop> argument. |
2256 | Stops the watcher if it is active. Again, no C<loop> argument. |
1770 | |
2257 | |
1771 | =item w->again () C<ev::timer>, C<ev::periodic> only |
2258 | =item w->again () (C<ev::timer>, C<ev::periodic> only) |
1772 | |
2259 | |
1773 | For C<ev::timer> and C<ev::periodic>, this invokes the corresponding |
2260 | For C<ev::timer> and C<ev::periodic>, this invokes the corresponding |
1774 | C<ev_TYPE_again> function. |
2261 | C<ev_TYPE_again> function. |
1775 | |
2262 | |
1776 | =item w->sweep () C<ev::embed> only |
2263 | =item w->sweep () (C<ev::embed> only) |
1777 | |
2264 | |
1778 | Invokes C<ev_embed_sweep>. |
2265 | Invokes C<ev_embed_sweep>. |
1779 | |
2266 | |
1780 | =item w->update () C<ev::stat> only |
2267 | =item w->update () (C<ev::stat> only) |
1781 | |
2268 | |
1782 | Invokes C<ev_stat_stat>. |
2269 | Invokes C<ev_stat_stat>. |
1783 | |
2270 | |
1784 | =back |
2271 | =back |
1785 | |
2272 | |
… | |
… | |
1795 | |
2282 | |
1796 | myclass (); |
2283 | myclass (); |
1797 | } |
2284 | } |
1798 | |
2285 | |
1799 | myclass::myclass (int fd) |
2286 | myclass::myclass (int fd) |
1800 | : io (this, &myclass::io_cb), |
|
|
1801 | idle (this, &myclass::idle_cb) |
|
|
1802 | { |
2287 | { |
|
|
2288 | io .set <myclass, &myclass::io_cb > (this); |
|
|
2289 | idle.set <myclass, &myclass::idle_cb> (this); |
|
|
2290 | |
1803 | io.start (fd, ev::READ); |
2291 | io.start (fd, ev::READ); |
1804 | } |
2292 | } |
1805 | |
2293 | |
1806 | |
2294 | |
1807 | =head1 MACRO MAGIC |
2295 | =head1 MACRO MAGIC |
1808 | |
2296 | |
1809 | Libev can be compiled with a variety of options, the most fundemantal is |
2297 | Libev can be compiled with a variety of options, the most fundamantal |
1810 | C<EV_MULTIPLICITY>. This option determines wether (most) functions and |
2298 | of which is C<EV_MULTIPLICITY>. This option determines whether (most) |
1811 | callbacks have an initial C<struct ev_loop *> argument. |
2299 | functions and callbacks have an initial C<struct ev_loop *> argument. |
1812 | |
2300 | |
1813 | To make it easier to write programs that cope with either variant, the |
2301 | To make it easier to write programs that cope with either variant, the |
1814 | following macros are defined: |
2302 | following macros are defined: |
1815 | |
2303 | |
1816 | =over 4 |
2304 | =over 4 |
… | |
… | |
1849 | loop, if multiple loops are supported ("ev loop default"). |
2337 | loop, if multiple loops are supported ("ev loop default"). |
1850 | |
2338 | |
1851 | =back |
2339 | =back |
1852 | |
2340 | |
1853 | Example: Declare and initialise a check watcher, utilising the above |
2341 | Example: Declare and initialise a check watcher, utilising the above |
1854 | macros so it will work regardless of wether multiple loops are supported |
2342 | macros so it will work regardless of whether multiple loops are supported |
1855 | or not. |
2343 | or not. |
1856 | |
2344 | |
1857 | static void |
2345 | static void |
1858 | check_cb (EV_P_ ev_timer *w, int revents) |
2346 | check_cb (EV_P_ ev_timer *w, int revents) |
1859 | { |
2347 | { |
… | |
… | |
1870 | Libev can (and often is) directly embedded into host |
2358 | Libev can (and often is) directly embedded into host |
1871 | applications. Examples of applications that embed it include the Deliantra |
2359 | applications. Examples of applications that embed it include the Deliantra |
1872 | Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe) |
2360 | Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe) |
1873 | and rxvt-unicode. |
2361 | and rxvt-unicode. |
1874 | |
2362 | |
1875 | The goal is to enable you to just copy the neecssary files into your |
2363 | The goal is to enable you to just copy the necessary files into your |
1876 | source directory without having to change even a single line in them, so |
2364 | source directory without having to change even a single line in them, so |
1877 | you can easily upgrade by simply copying (or having a checked-out copy of |
2365 | you can easily upgrade by simply copying (or having a checked-out copy of |
1878 | libev somewhere in your source tree). |
2366 | libev somewhere in your source tree). |
1879 | |
2367 | |
1880 | =head2 FILESETS |
2368 | =head2 FILESETS |
… | |
… | |
1970 | |
2458 | |
1971 | If defined to be C<1>, libev will try to detect the availability of the |
2459 | If defined to be C<1>, libev will try to detect the availability of the |
1972 | monotonic clock option at both compiletime and runtime. Otherwise no use |
2460 | monotonic clock option at both compiletime and runtime. Otherwise no use |
1973 | of the monotonic clock option will be attempted. If you enable this, you |
2461 | of the monotonic clock option will be attempted. If you enable this, you |
1974 | usually have to link against librt or something similar. Enabling it when |
2462 | usually have to link against librt or something similar. Enabling it when |
1975 | the functionality isn't available is safe, though, althoguh you have |
2463 | the functionality isn't available is safe, though, although you have |
1976 | to make sure you link against any libraries where the C<clock_gettime> |
2464 | to make sure you link against any libraries where the C<clock_gettime> |
1977 | function is hiding in (often F<-lrt>). |
2465 | function is hiding in (often F<-lrt>). |
1978 | |
2466 | |
1979 | =item EV_USE_REALTIME |
2467 | =item EV_USE_REALTIME |
1980 | |
2468 | |
1981 | If defined to be C<1>, libev will try to detect the availability of the |
2469 | If defined to be C<1>, libev will try to detect the availability of the |
1982 | realtime clock option at compiletime (and assume its availability at |
2470 | realtime clock option at compiletime (and assume its availability at |
1983 | runtime if successful). Otherwise no use of the realtime clock option will |
2471 | runtime if successful). Otherwise no use of the realtime clock option will |
1984 | be attempted. This effectively replaces C<gettimeofday> by C<clock_get |
2472 | be attempted. This effectively replaces C<gettimeofday> by C<clock_get |
1985 | (CLOCK_REALTIME, ...)> and will not normally affect correctness. See tzhe note about libraries |
2473 | (CLOCK_REALTIME, ...)> and will not normally affect correctness. See the |
1986 | in the description of C<EV_USE_MONOTONIC>, though. |
2474 | note about libraries in the description of C<EV_USE_MONOTONIC>, though. |
|
|
2475 | |
|
|
2476 | =item EV_USE_NANOSLEEP |
|
|
2477 | |
|
|
2478 | If defined to be C<1>, libev will assume that C<nanosleep ()> is available |
|
|
2479 | and will use it for delays. Otherwise it will use C<select ()>. |
1987 | |
2480 | |
1988 | =item EV_USE_SELECT |
2481 | =item EV_USE_SELECT |
1989 | |
2482 | |
1990 | If undefined or defined to be C<1>, libev will compile in support for the |
2483 | If undefined or defined to be C<1>, libev will compile in support for the |
1991 | C<select>(2) backend. No attempt at autodetection will be done: if no |
2484 | C<select>(2) backend. No attempt at autodetection will be done: if no |
… | |
… | |
2009 | wants osf handles on win32 (this is the case when the select to |
2502 | wants osf handles on win32 (this is the case when the select to |
2010 | be used is the winsock select). This means that it will call |
2503 | be used is the winsock select). This means that it will call |
2011 | C<_get_osfhandle> on the fd to convert it to an OS handle. Otherwise, |
2504 | C<_get_osfhandle> on the fd to convert it to an OS handle. Otherwise, |
2012 | it is assumed that all these functions actually work on fds, even |
2505 | it is assumed that all these functions actually work on fds, even |
2013 | on win32. Should not be defined on non-win32 platforms. |
2506 | on win32. Should not be defined on non-win32 platforms. |
|
|
2507 | |
|
|
2508 | =item EV_FD_TO_WIN32_HANDLE |
|
|
2509 | |
|
|
2510 | If C<EV_SELECT_IS_WINSOCKET> is enabled, then libev needs a way to map |
|
|
2511 | file descriptors to socket handles. When not defining this symbol (the |
|
|
2512 | default), then libev will call C<_get_osfhandle>, which is usually |
|
|
2513 | correct. In some cases, programs use their own file descriptor management, |
|
|
2514 | in which case they can provide this function to map fds to socket handles. |
2014 | |
2515 | |
2015 | =item EV_USE_POLL |
2516 | =item EV_USE_POLL |
2016 | |
2517 | |
2017 | If defined to be C<1>, libev will compile in support for the C<poll>(2) |
2518 | If defined to be C<1>, libev will compile in support for the C<poll>(2) |
2018 | backend. Otherwise it will be enabled on non-win32 platforms. It |
2519 | backend. Otherwise it will be enabled on non-win32 platforms. It |
… | |
… | |
2055 | be detected at runtime. |
2556 | be detected at runtime. |
2056 | |
2557 | |
2057 | =item EV_H |
2558 | =item EV_H |
2058 | |
2559 | |
2059 | The name of the F<ev.h> header file used to include it. The default if |
2560 | The name of the F<ev.h> header file used to include it. The default if |
2060 | undefined is C<< <ev.h> >> in F<event.h> and C<"ev.h"> in F<ev.c>. This |
2561 | undefined is C<"ev.h"> in F<event.h> and F<ev.c>. This can be used to |
2061 | can be used to virtually rename the F<ev.h> header file in case of conflicts. |
2562 | virtually rename the F<ev.h> header file in case of conflicts. |
2062 | |
2563 | |
2063 | =item EV_CONFIG_H |
2564 | =item EV_CONFIG_H |
2064 | |
2565 | |
2065 | If C<EV_STANDALONE> isn't C<1>, this variable can be used to override |
2566 | If C<EV_STANDALONE> isn't C<1>, this variable can be used to override |
2066 | F<ev.c>'s idea of where to find the F<config.h> file, similarly to |
2567 | F<ev.c>'s idea of where to find the F<config.h> file, similarly to |
2067 | C<EV_H>, above. |
2568 | C<EV_H>, above. |
2068 | |
2569 | |
2069 | =item EV_EVENT_H |
2570 | =item EV_EVENT_H |
2070 | |
2571 | |
2071 | Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea |
2572 | Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea |
2072 | of how the F<event.h> header can be found. |
2573 | of how the F<event.h> header can be found, the dfeault is C<"event.h">. |
2073 | |
2574 | |
2074 | =item EV_PROTOTYPES |
2575 | =item EV_PROTOTYPES |
2075 | |
2576 | |
2076 | If defined to be C<0>, then F<ev.h> will not define any function |
2577 | If defined to be C<0>, then F<ev.h> will not define any function |
2077 | prototypes, but still define all the structs and other symbols. This is |
2578 | prototypes, but still define all the structs and other symbols. This is |
… | |
… | |
2084 | will have the C<struct ev_loop *> as first argument, and you can create |
2585 | will have the C<struct ev_loop *> as first argument, and you can create |
2085 | additional independent event loops. Otherwise there will be no support |
2586 | additional independent event loops. Otherwise there will be no support |
2086 | for multiple event loops and there is no first event loop pointer |
2587 | for multiple event loops and there is no first event loop pointer |
2087 | argument. Instead, all functions act on the single default loop. |
2588 | argument. Instead, all functions act on the single default loop. |
2088 | |
2589 | |
|
|
2590 | =item EV_MINPRI |
|
|
2591 | |
|
|
2592 | =item EV_MAXPRI |
|
|
2593 | |
|
|
2594 | The range of allowed priorities. C<EV_MINPRI> must be smaller or equal to |
|
|
2595 | C<EV_MAXPRI>, but otherwise there are no non-obvious limitations. You can |
|
|
2596 | provide for more priorities by overriding those symbols (usually defined |
|
|
2597 | to be C<-2> and C<2>, respectively). |
|
|
2598 | |
|
|
2599 | When doing priority-based operations, libev usually has to linearly search |
|
|
2600 | all the priorities, so having many of them (hundreds) uses a lot of space |
|
|
2601 | and time, so using the defaults of five priorities (-2 .. +2) is usually |
|
|
2602 | fine. |
|
|
2603 | |
|
|
2604 | If your embedding app does not need any priorities, defining these both to |
|
|
2605 | C<0> will save some memory and cpu. |
|
|
2606 | |
2089 | =item EV_PERIODIC_ENABLE |
2607 | =item EV_PERIODIC_ENABLE |
2090 | |
2608 | |
2091 | If undefined or defined to be C<1>, then periodic timers are supported. If |
2609 | If undefined or defined to be C<1>, then periodic timers are supported. If |
|
|
2610 | defined to be C<0>, then they are not. Disabling them saves a few kB of |
|
|
2611 | code. |
|
|
2612 | |
|
|
2613 | =item EV_IDLE_ENABLE |
|
|
2614 | |
|
|
2615 | If undefined or defined to be C<1>, then idle watchers are supported. If |
2092 | defined to be C<0>, then they are not. Disabling them saves a few kB of |
2616 | defined to be C<0>, then they are not. Disabling them saves a few kB of |
2093 | code. |
2617 | code. |
2094 | |
2618 | |
2095 | =item EV_EMBED_ENABLE |
2619 | =item EV_EMBED_ENABLE |
2096 | |
2620 | |
… | |
… | |
2120 | than enough. If you need to manage thousands of children you might want to |
2644 | than enough. If you need to manage thousands of children you might want to |
2121 | increase this value (I<must> be a power of two). |
2645 | increase this value (I<must> be a power of two). |
2122 | |
2646 | |
2123 | =item EV_INOTIFY_HASHSIZE |
2647 | =item EV_INOTIFY_HASHSIZE |
2124 | |
2648 | |
2125 | C<ev_staz> watchers use a small hash table to distribute workload by |
2649 | C<ev_stat> watchers use a small hash table to distribute workload by |
2126 | inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>), |
2650 | inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>), |
2127 | usually more than enough. If you need to manage thousands of C<ev_stat> |
2651 | usually more than enough. If you need to manage thousands of C<ev_stat> |
2128 | watchers you might want to increase this value (I<must> be a power of |
2652 | watchers you might want to increase this value (I<must> be a power of |
2129 | two). |
2653 | two). |
2130 | |
2654 | |
… | |
… | |
2147 | |
2671 | |
2148 | =item ev_set_cb (ev, cb) |
2672 | =item ev_set_cb (ev, cb) |
2149 | |
2673 | |
2150 | Can be used to change the callback member declaration in each watcher, |
2674 | Can be used to change the callback member declaration in each watcher, |
2151 | and the way callbacks are invoked and set. Must expand to a struct member |
2675 | and the way callbacks are invoked and set. Must expand to a struct member |
2152 | definition and a statement, respectively. See the F<ev.v> header file for |
2676 | definition and a statement, respectively. See the F<ev.h> header file for |
2153 | their default definitions. One possible use for overriding these is to |
2677 | their default definitions. One possible use for overriding these is to |
2154 | avoid the C<struct ev_loop *> as first argument in all cases, or to use |
2678 | avoid the C<struct ev_loop *> as first argument in all cases, or to use |
2155 | method calls instead of plain function calls in C++. |
2679 | method calls instead of plain function calls in C++. |
|
|
2680 | |
|
|
2681 | =head2 EXPORTED API SYMBOLS |
|
|
2682 | |
|
|
2683 | If you need to re-export the API (e.g. via a dll) and you need a list of |
|
|
2684 | exported symbols, you can use the provided F<Symbol.*> files which list |
|
|
2685 | all public symbols, one per line: |
|
|
2686 | |
|
|
2687 | Symbols.ev for libev proper |
|
|
2688 | Symbols.event for the libevent emulation |
|
|
2689 | |
|
|
2690 | This can also be used to rename all public symbols to avoid clashes with |
|
|
2691 | multiple versions of libev linked together (which is obviously bad in |
|
|
2692 | itself, but sometimes it is inconvinient to avoid this). |
|
|
2693 | |
|
|
2694 | A sed command like this will create wrapper C<#define>'s that you need to |
|
|
2695 | include before including F<ev.h>: |
|
|
2696 | |
|
|
2697 | <Symbols.ev sed -e "s/.*/#define & myprefix_&/" >wrap.h |
|
|
2698 | |
|
|
2699 | This would create a file F<wrap.h> which essentially looks like this: |
|
|
2700 | |
|
|
2701 | #define ev_backend myprefix_ev_backend |
|
|
2702 | #define ev_check_start myprefix_ev_check_start |
|
|
2703 | #define ev_check_stop myprefix_ev_check_stop |
|
|
2704 | ... |
2156 | |
2705 | |
2157 | =head2 EXAMPLES |
2706 | =head2 EXAMPLES |
2158 | |
2707 | |
2159 | For a real-world example of a program the includes libev |
2708 | For a real-world example of a program the includes libev |
2160 | verbatim, you can have a look at the EV perl module |
2709 | verbatim, you can have a look at the EV perl module |
… | |
… | |
2189 | |
2738 | |
2190 | In this section the complexities of (many of) the algorithms used inside |
2739 | In this section the complexities of (many of) the algorithms used inside |
2191 | libev will be explained. For complexity discussions about backends see the |
2740 | libev will be explained. For complexity discussions about backends see the |
2192 | documentation for C<ev_default_init>. |
2741 | documentation for C<ev_default_init>. |
2193 | |
2742 | |
|
|
2743 | All of the following are about amortised time: If an array needs to be |
|
|
2744 | extended, libev needs to realloc and move the whole array, but this |
|
|
2745 | happens asymptotically never with higher number of elements, so O(1) might |
|
|
2746 | mean it might do a lengthy realloc operation in rare cases, but on average |
|
|
2747 | it is much faster and asymptotically approaches constant time. |
|
|
2748 | |
2194 | =over 4 |
2749 | =over 4 |
2195 | |
2750 | |
2196 | =item Starting and stopping timer/periodic watchers: O(log skipped_other_timers) |
2751 | =item Starting and stopping timer/periodic watchers: O(log skipped_other_timers) |
2197 | |
2752 | |
|
|
2753 | This means that, when you have a watcher that triggers in one hour and |
|
|
2754 | there are 100 watchers that would trigger before that then inserting will |
|
|
2755 | have to skip roughly seven (C<ld 100>) of these watchers. |
|
|
2756 | |
2198 | =item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers) |
2757 | =item Changing timer/periodic watchers (by autorepeat or calling again): O(log skipped_other_timers) |
|
|
2758 | |
|
|
2759 | That means that changing a timer costs less than removing/adding them |
|
|
2760 | as only the relative motion in the event queue has to be paid for. |
2199 | |
2761 | |
2200 | =item Starting io/check/prepare/idle/signal/child watchers: O(1) |
2762 | =item Starting io/check/prepare/idle/signal/child watchers: O(1) |
2201 | |
2763 | |
|
|
2764 | These just add the watcher into an array or at the head of a list. |
|
|
2765 | |
2202 | =item Stopping check/prepare/idle watchers: O(1) |
2766 | =item Stopping check/prepare/idle watchers: O(1) |
2203 | |
2767 | |
2204 | =item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE)) |
2768 | =item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE)) |
2205 | |
2769 | |
|
|
2770 | These watchers are stored in lists then need to be walked to find the |
|
|
2771 | correct watcher to remove. The lists are usually short (you don't usually |
|
|
2772 | have many watchers waiting for the same fd or signal). |
|
|
2773 | |
2206 | =item Finding the next timer per loop iteration: O(1) |
2774 | =item Finding the next timer in each loop iteration: O(1) |
|
|
2775 | |
|
|
2776 | By virtue of using a binary heap, the next timer is always found at the |
|
|
2777 | beginning of the storage array. |
2207 | |
2778 | |
2208 | =item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd) |
2779 | =item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd) |
2209 | |
2780 | |
2210 | =item Activating one watcher: O(1) |
2781 | A change means an I/O watcher gets started or stopped, which requires |
|
|
2782 | libev to recalculate its status (and possibly tell the kernel, depending |
|
|
2783 | on backend and wether C<ev_io_set> was used). |
|
|
2784 | |
|
|
2785 | =item Activating one watcher (putting it into the pending state): O(1) |
|
|
2786 | |
|
|
2787 | =item Priority handling: O(number_of_priorities) |
|
|
2788 | |
|
|
2789 | Priorities are implemented by allocating some space for each |
|
|
2790 | priority. When doing priority-based operations, libev usually has to |
|
|
2791 | linearly search all the priorities, but starting/stopping and activating |
|
|
2792 | watchers becomes O(1) w.r.t. prioritiy handling. |
2211 | |
2793 | |
2212 | =back |
2794 | =back |
2213 | |
2795 | |
2214 | |
2796 | |
|
|
2797 | =head1 Win32 platform limitations and workarounds |
|
|
2798 | |
|
|
2799 | Win32 doesn't support any of the standards (e.g. POSIX) that libev |
|
|
2800 | requires, and its I/O model is fundamentally incompatible with the POSIX |
|
|
2801 | model. Libev still offers limited functionality on this platform in |
|
|
2802 | the form of the C<EVBACKEND_SELECT> backend, and only supports socket |
|
|
2803 | descriptors. This only applies when using Win32 natively, not when using |
|
|
2804 | e.g. cygwin. |
|
|
2805 | |
|
|
2806 | There is no supported compilation method available on windows except |
|
|
2807 | embedding it into other applications. |
|
|
2808 | |
|
|
2809 | Due to the many, low, and arbitrary limits on the win32 platform and the |
|
|
2810 | abysmal performance of winsockets, using a large number of sockets is not |
|
|
2811 | recommended (and not reasonable). If your program needs to use more than |
|
|
2812 | a hundred or so sockets, then likely it needs to use a totally different |
|
|
2813 | implementation for windows, as libev offers the POSIX model, which cannot |
|
|
2814 | be implemented efficiently on windows (microsoft monopoly games). |
|
|
2815 | |
|
|
2816 | =over 4 |
|
|
2817 | |
|
|
2818 | =item The winsocket select function |
|
|
2819 | |
|
|
2820 | The winsocket C<select> function doesn't follow POSIX in that it requires |
|
|
2821 | socket I<handles> and not socket I<file descriptors>. This makes select |
|
|
2822 | very inefficient, and also requires a mapping from file descriptors |
|
|
2823 | to socket handles. See the discussion of the C<EV_SELECT_USE_FD_SET>, |
|
|
2824 | C<EV_SELECT_IS_WINSOCKET> and C<EV_FD_TO_WIN32_HANDLE> preprocessor |
|
|
2825 | symbols for more info. |
|
|
2826 | |
|
|
2827 | The configuration for a "naked" win32 using the microsoft runtime |
|
|
2828 | libraries and raw winsocket select is: |
|
|
2829 | |
|
|
2830 | #define EV_USE_SELECT 1 |
|
|
2831 | #define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */ |
|
|
2832 | |
|
|
2833 | Note that winsockets handling of fd sets is O(n), so you can easily get a |
|
|
2834 | complexity in the O(n²) range when using win32. |
|
|
2835 | |
|
|
2836 | =item Limited number of file descriptors |
|
|
2837 | |
|
|
2838 | Windows has numerous arbitrary (and low) limits on things. Early versions |
|
|
2839 | of winsocket's select only supported waiting for a max. of C<64> handles |
|
|
2840 | (probably owning to the fact that all windows kernels can only wait for |
|
|
2841 | C<64> things at the same time internally; microsoft recommends spawning a |
|
|
2842 | chain of threads and wait for 63 handles and the previous thread in each). |
|
|
2843 | |
|
|
2844 | Newer versions support more handles, but you need to define C<FD_SETSIZE> |
|
|
2845 | to some high number (e.g. C<2048>) before compiling the winsocket select |
|
|
2846 | call (which might be in libev or elsewhere, for example, perl does its own |
|
|
2847 | select emulation on windows). |
|
|
2848 | |
|
|
2849 | Another limit is the number of file descriptors in the microsoft runtime |
|
|
2850 | libraries, which by default is C<64> (there must be a hidden I<64> fetish |
|
|
2851 | or something like this inside microsoft). You can increase this by calling |
|
|
2852 | C<_setmaxstdio>, which can increase this limit to C<2048> (another |
|
|
2853 | arbitrary limit), but is broken in many versions of the microsoft runtime |
|
|
2854 | libraries. |
|
|
2855 | |
|
|
2856 | This might get you to about C<512> or C<2048> sockets (depending on |
|
|
2857 | windows version and/or the phase of the moon). To get more, you need to |
|
|
2858 | wrap all I/O functions and provide your own fd management, but the cost of |
|
|
2859 | calling select (O(n²)) will likely make this unworkable. |
|
|
2860 | |
|
|
2861 | =back |
|
|
2862 | |
|
|
2863 | |
2215 | =head1 AUTHOR |
2864 | =head1 AUTHOR |
2216 | |
2865 | |
2217 | Marc Lehmann <libev@schmorp.de>. |
2866 | Marc Lehmann <libev@schmorp.de>. |
2218 | |
2867 | |