… | |
… | |
26 | puts ("stdin ready"); |
26 | puts ("stdin ready"); |
27 | // for one-shot events, one must manually stop the watcher |
27 | // for one-shot events, one must manually stop the watcher |
28 | // with its corresponding stop function. |
28 | // with its corresponding stop function. |
29 | ev_io_stop (EV_A_ w); |
29 | ev_io_stop (EV_A_ w); |
30 | |
30 | |
31 | // this causes all nested ev_loop's to stop iterating |
31 | // this causes all nested ev_run's to stop iterating |
32 | ev_unloop (EV_A_ EVUNLOOP_ALL); |
32 | ev_break (EV_A_ EVBREAK_ALL); |
33 | } |
33 | } |
34 | |
34 | |
35 | // another callback, this time for a time-out |
35 | // another callback, this time for a time-out |
36 | static void |
36 | static void |
37 | timeout_cb (EV_P_ ev_timer *w, int revents) |
37 | timeout_cb (EV_P_ ev_timer *w, int revents) |
38 | { |
38 | { |
39 | puts ("timeout"); |
39 | puts ("timeout"); |
40 | // this causes the innermost ev_loop to stop iterating |
40 | // this causes the innermost ev_run to stop iterating |
41 | ev_unloop (EV_A_ EVUNLOOP_ONE); |
41 | ev_break (EV_A_ EVBREAK_ONE); |
42 | } |
42 | } |
43 | |
43 | |
44 | int |
44 | int |
45 | main (void) |
45 | main (void) |
46 | { |
46 | { |
… | |
… | |
56 | // simple non-repeating 5.5 second timeout |
56 | // simple non-repeating 5.5 second timeout |
57 | ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.); |
57 | ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.); |
58 | ev_timer_start (loop, &timeout_watcher); |
58 | ev_timer_start (loop, &timeout_watcher); |
59 | |
59 | |
60 | // now wait for events to arrive |
60 | // now wait for events to arrive |
61 | ev_loop (loop, 0); |
61 | ev_run (loop, 0); |
62 | |
62 | |
63 | // unloop was called, so exit |
63 | // unloop was called, so exit |
64 | return 0; |
64 | return 0; |
65 | } |
65 | } |
66 | |
66 | |
67 | =head1 DESCRIPTION |
67 | =head1 ABOUT THIS DOCUMENT |
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68 | |
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69 | This document documents the libev software package. |
68 | |
70 | |
69 | The newest version of this document is also available as an html-formatted |
71 | The newest version of this document is also available as an html-formatted |
70 | web page you might find easier to navigate when reading it for the first |
72 | web page you might find easier to navigate when reading it for the first |
71 | time: L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod>. |
73 | time: L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod>. |
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74 | |
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75 | While this document tries to be as complete as possible in documenting |
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76 | libev, its usage and the rationale behind its design, it is not a tutorial |
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77 | on event-based programming, nor will it introduce event-based programming |
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78 | with libev. |
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79 | |
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80 | Familiarity with event based programming techniques in general is assumed |
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81 | throughout this document. |
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82 | |
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83 | =head1 ABOUT LIBEV |
72 | |
84 | |
73 | Libev is an event loop: you register interest in certain events (such as a |
85 | Libev is an event loop: you register interest in certain events (such as a |
74 | file descriptor being readable or a timeout occurring), and it will manage |
86 | file descriptor being readable or a timeout occurring), and it will manage |
75 | these event sources and provide your program with events. |
87 | these event sources and provide your program with events. |
76 | |
88 | |
… | |
… | |
86 | =head2 FEATURES |
98 | =head2 FEATURES |
87 | |
99 | |
88 | Libev supports C<select>, C<poll>, the Linux-specific C<epoll>, the |
100 | Libev supports C<select>, C<poll>, the Linux-specific C<epoll>, the |
89 | BSD-specific C<kqueue> and the Solaris-specific event port mechanisms |
101 | BSD-specific C<kqueue> and the Solaris-specific event port mechanisms |
90 | for file descriptor events (C<ev_io>), the Linux C<inotify> interface |
102 | for file descriptor events (C<ev_io>), the Linux C<inotify> interface |
91 | (for C<ev_stat>), relative timers (C<ev_timer>), absolute timers |
103 | (for C<ev_stat>), Linux eventfd/signalfd (for faster and cleaner |
92 | with customised rescheduling (C<ev_periodic>), synchronous signals |
104 | inter-thread wakeup (C<ev_async>)/signal handling (C<ev_signal>)) relative |
93 | (C<ev_signal>), process status change events (C<ev_child>), and event |
105 | timers (C<ev_timer>), absolute timers with customised rescheduling |
94 | watchers dealing with the event loop mechanism itself (C<ev_idle>, |
106 | (C<ev_periodic>), synchronous signals (C<ev_signal>), process status |
95 | C<ev_embed>, C<ev_prepare> and C<ev_check> watchers) as well as |
107 | change events (C<ev_child>), and event watchers dealing with the event |
96 | file watchers (C<ev_stat>) and even limited support for fork events |
108 | loop mechanism itself (C<ev_idle>, C<ev_embed>, C<ev_prepare> and |
97 | (C<ev_fork>). |
109 | C<ev_check> watchers) as well as file watchers (C<ev_stat>) and even |
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110 | limited support for fork events (C<ev_fork>). |
98 | |
111 | |
99 | It also is quite fast (see this |
112 | It also is quite fast (see this |
100 | L<benchmark|http://libev.schmorp.de/bench.html> comparing it to libevent |
113 | L<benchmark|http://libev.schmorp.de/bench.html> comparing it to libevent |
101 | for example). |
114 | for example). |
102 | |
115 | |
… | |
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105 | Libev is very configurable. In this manual the default (and most common) |
118 | Libev is very configurable. In this manual the default (and most common) |
106 | configuration will be described, which supports multiple event loops. For |
119 | configuration will be described, which supports multiple event loops. For |
107 | more info about various configuration options please have a look at |
120 | more info about various configuration options please have a look at |
108 | B<EMBED> section in this manual. If libev was configured without support |
121 | B<EMBED> section in this manual. If libev was configured without support |
109 | for multiple event loops, then all functions taking an initial argument of |
122 | for multiple event loops, then all functions taking an initial argument of |
110 | name C<loop> (which is always of type C<ev_loop *>) will not have |
123 | name C<loop> (which is always of type C<struct ev_loop *>) will not have |
111 | this argument. |
124 | this argument. |
112 | |
125 | |
113 | =head2 TIME REPRESENTATION |
126 | =head2 TIME REPRESENTATION |
114 | |
127 | |
115 | Libev represents time as a single floating point number, representing the |
128 | Libev represents time as a single floating point number, representing |
116 | (fractional) number of seconds since the (POSIX) epoch (somewhere near |
129 | the (fractional) number of seconds since the (POSIX) epoch (in practise |
117 | the beginning of 1970, details are complicated, don't ask). This type is |
130 | somewhere near the beginning of 1970, details are complicated, don't |
118 | called C<ev_tstamp>, which is what you should use too. It usually aliases |
131 | ask). This type is called C<ev_tstamp>, which is what you should use |
119 | to the C<double> type in C, and when you need to do any calculations on |
132 | too. It usually aliases to the C<double> type in C. When you need to do |
120 | it, you should treat it as some floating point value. Unlike the name |
133 | any calculations on it, you should treat it as some floating point value. |
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134 | |
121 | component C<stamp> might indicate, it is also used for time differences |
135 | Unlike the name component C<stamp> might indicate, it is also used for |
122 | throughout libev. |
136 | time differences (e.g. delays) throughout libev. |
123 | |
137 | |
124 | =head1 ERROR HANDLING |
138 | =head1 ERROR HANDLING |
125 | |
139 | |
126 | Libev knows three classes of errors: operating system errors, usage errors |
140 | Libev knows three classes of errors: operating system errors, usage errors |
127 | and internal errors (bugs). |
141 | and internal errors (bugs). |
… | |
… | |
178 | as this indicates an incompatible change. Minor versions are usually |
192 | as this indicates an incompatible change. Minor versions are usually |
179 | compatible to older versions, so a larger minor version alone is usually |
193 | compatible to older versions, so a larger minor version alone is usually |
180 | not a problem. |
194 | not a problem. |
181 | |
195 | |
182 | Example: Make sure we haven't accidentally been linked against the wrong |
196 | Example: Make sure we haven't accidentally been linked against the wrong |
183 | version. |
197 | version (note, however, that this will not detect ABI mismatches :). |
184 | |
198 | |
185 | assert (("libev version mismatch", |
199 | assert (("libev version mismatch", |
186 | ev_version_major () == EV_VERSION_MAJOR |
200 | ev_version_major () == EV_VERSION_MAJOR |
187 | && ev_version_minor () >= EV_VERSION_MINOR)); |
201 | && ev_version_minor () >= EV_VERSION_MINOR)); |
188 | |
202 | |
… | |
… | |
278 | |
292 | |
279 | =back |
293 | =back |
280 | |
294 | |
281 | =head1 FUNCTIONS CONTROLLING THE EVENT LOOP |
295 | =head1 FUNCTIONS CONTROLLING THE EVENT LOOP |
282 | |
296 | |
283 | An event loop is described by a C<struct ev_loop *> (the C<struct> |
297 | An event loop is described by a C<struct ev_loop *> (the C<struct> is |
284 | is I<not> optional in this case, as there is also an C<ev_loop> |
298 | I<not> optional in case unless libev 3 compatibility is disabled, as libev |
285 | I<function>). |
299 | 3 had an C<ev_loop> function colliding with the struct name). |
286 | |
300 | |
287 | The library knows two types of such loops, the I<default> loop, which |
301 | The library knows two types of such loops, the I<default> loop, which |
288 | supports signals and child events, and dynamically created loops which do |
302 | supports signals and child events, and dynamically created event loops |
289 | not. |
303 | which do not. |
290 | |
304 | |
291 | =over 4 |
305 | =over 4 |
292 | |
306 | |
293 | =item struct ev_loop *ev_default_loop (unsigned int flags) |
307 | =item struct ev_loop *ev_default_loop (unsigned int flags) |
294 | |
308 | |
… | |
… | |
332 | useful to try out specific backends to test their performance, or to work |
346 | useful to try out specific backends to test their performance, or to work |
333 | around bugs. |
347 | around bugs. |
334 | |
348 | |
335 | =item C<EVFLAG_FORKCHECK> |
349 | =item C<EVFLAG_FORKCHECK> |
336 | |
350 | |
337 | Instead of calling C<ev_default_fork> or C<ev_loop_fork> manually after |
351 | Instead of calling C<ev_loop_fork> manually after a fork, you can also |
338 | a fork, you can also make libev check for a fork in each iteration by |
352 | make libev check for a fork in each iteration by enabling this flag. |
339 | enabling this flag. |
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340 | |
353 | |
341 | This works by calling C<getpid ()> on every iteration of the loop, |
354 | This works by calling C<getpid ()> on every iteration of the loop, |
342 | and thus this might slow down your event loop if you do a lot of loop |
355 | and thus this might slow down your event loop if you do a lot of loop |
343 | iterations and little real work, but is usually not noticeable (on my |
356 | iterations and little real work, but is usually not noticeable (on my |
344 | GNU/Linux system for example, C<getpid> is actually a simple 5-insn sequence |
357 | GNU/Linux system for example, C<getpid> is actually a simple 5-insn sequence |
… | |
… | |
350 | flag. |
363 | flag. |
351 | |
364 | |
352 | This flag setting cannot be overridden or specified in the C<LIBEV_FLAGS> |
365 | This flag setting cannot be overridden or specified in the C<LIBEV_FLAGS> |
353 | environment variable. |
366 | environment variable. |
354 | |
367 | |
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368 | =item C<EVFLAG_NOINOTIFY> |
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369 | |
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370 | When this flag is specified, then libev will not attempt to use the |
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371 | I<inotify> API for it's C<ev_stat> watchers. Apart from debugging and |
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372 | testing, this flag can be useful to conserve inotify file descriptors, as |
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373 | otherwise each loop using C<ev_stat> watchers consumes one inotify handle. |
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374 | |
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375 | =item C<EVFLAG_SIGNALFD> |
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376 | |
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377 | When this flag is specified, then libev will attempt to use the |
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378 | I<signalfd> API for it's C<ev_signal> (and C<ev_child>) watchers. This API |
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379 | delivers signals synchronously, which makes it both faster and might make |
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380 | it possible to get the queued signal data. It can also simplify signal |
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381 | handling with threads, as long as you properly block signals in your |
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382 | threads that are not interested in handling them. |
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383 | |
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384 | Signalfd will not be used by default as this changes your signal mask, and |
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385 | there are a lot of shoddy libraries and programs (glib's threadpool for |
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386 | example) that can't properly initialise their signal masks. |
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387 | |
355 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
388 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
356 | |
389 | |
357 | This is your standard select(2) backend. Not I<completely> standard, as |
390 | This is your standard select(2) backend. Not I<completely> standard, as |
358 | libev tries to roll its own fd_set with no limits on the number of fds, |
391 | libev tries to roll its own fd_set with no limits on the number of fds, |
359 | but if that fails, expect a fairly low limit on the number of fds when |
392 | but if that fails, expect a fairly low limit on the number of fds when |
… | |
… | |
382 | |
415 | |
383 | This backend maps C<EV_READ> to C<POLLIN | POLLERR | POLLHUP>, and |
416 | This backend maps C<EV_READ> to C<POLLIN | POLLERR | POLLHUP>, and |
384 | C<EV_WRITE> to C<POLLOUT | POLLERR | POLLHUP>. |
417 | C<EV_WRITE> to C<POLLOUT | POLLERR | POLLHUP>. |
385 | |
418 | |
386 | =item C<EVBACKEND_EPOLL> (value 4, Linux) |
419 | =item C<EVBACKEND_EPOLL> (value 4, Linux) |
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420 | |
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421 | Use the linux-specific epoll(7) interface (for both pre- and post-2.6.9 |
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422 | kernels). |
387 | |
423 | |
388 | For few fds, this backend is a bit little slower than poll and select, |
424 | For few fds, this backend is a bit little slower than poll and select, |
389 | but it scales phenomenally better. While poll and select usually scale |
425 | but it scales phenomenally better. While poll and select usually scale |
390 | like O(total_fds) where n is the total number of fds (or the highest fd), |
426 | like O(total_fds) where n is the total number of fds (or the highest fd), |
391 | epoll scales either O(1) or O(active_fds). |
427 | epoll scales either O(1) or O(active_fds). |
… | |
… | |
403 | of course I<doesn't>, and epoll just loves to report events for totally |
439 | of course I<doesn't>, and epoll just loves to report events for totally |
404 | I<different> file descriptors (even already closed ones, so one cannot |
440 | I<different> file descriptors (even already closed ones, so one cannot |
405 | even remove them from the set) than registered in the set (especially |
441 | even remove them from the set) than registered in the set (especially |
406 | on SMP systems). Libev tries to counter these spurious notifications by |
442 | on SMP systems). Libev tries to counter these spurious notifications by |
407 | employing an additional generation counter and comparing that against the |
443 | employing an additional generation counter and comparing that against the |
408 | events to filter out spurious ones, recreating the set when required. |
444 | events to filter out spurious ones, recreating the set when required. Last |
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445 | not least, it also refuses to work with some file descriptors which work |
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446 | perfectly fine with C<select> (files, many character devices...). |
409 | |
447 | |
410 | While stopping, setting and starting an I/O watcher in the same iteration |
448 | While stopping, setting and starting an I/O watcher in the same iteration |
411 | will result in some caching, there is still a system call per such |
449 | will result in some caching, there is still a system call per such |
412 | incident (because the same I<file descriptor> could point to a different |
450 | incident (because the same I<file descriptor> could point to a different |
413 | I<file description> now), so its best to avoid that. Also, C<dup ()>'ed |
451 | I<file description> now), so its best to avoid that. Also, C<dup ()>'ed |
… | |
… | |
506 | |
544 | |
507 | It is definitely not recommended to use this flag. |
545 | It is definitely not recommended to use this flag. |
508 | |
546 | |
509 | =back |
547 | =back |
510 | |
548 | |
511 | If one or more of these are or'ed into the flags value, then only these |
549 | If one or more of the backend flags are or'ed into the flags value, |
512 | backends will be tried (in the reverse order as listed here). If none are |
550 | then only these backends will be tried (in the reverse order as listed |
513 | specified, all backends in C<ev_recommended_backends ()> will be tried. |
551 | here). If none are specified, all backends in C<ev_recommended_backends |
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552 | ()> will be tried. |
514 | |
553 | |
515 | Example: This is the most typical usage. |
554 | Example: This is the most typical usage. |
516 | |
555 | |
517 | if (!ev_default_loop (0)) |
556 | if (!ev_default_loop (0)) |
518 | fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?"); |
557 | fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?"); |
… | |
… | |
530 | ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE); |
569 | ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE); |
531 | |
570 | |
532 | =item struct ev_loop *ev_loop_new (unsigned int flags) |
571 | =item struct ev_loop *ev_loop_new (unsigned int flags) |
533 | |
572 | |
534 | Similar to C<ev_default_loop>, but always creates a new event loop that is |
573 | Similar to C<ev_default_loop>, but always creates a new event loop that is |
535 | always distinct from the default loop. Unlike the default loop, it cannot |
574 | always distinct from the default loop. |
536 | handle signal and child watchers, and attempts to do so will be greeted by |
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537 | undefined behaviour (or a failed assertion if assertions are enabled). |
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538 | |
575 | |
539 | Note that this function I<is> thread-safe, and the recommended way to use |
576 | Note that this function I<is> thread-safe, and one common way to use |
540 | libev with threads is indeed to create one loop per thread, and using the |
577 | libev with threads is indeed to create one loop per thread, and using the |
541 | default loop in the "main" or "initial" thread. |
578 | default loop in the "main" or "initial" thread. |
542 | |
579 | |
543 | Example: Try to create a event loop that uses epoll and nothing else. |
580 | Example: Try to create a event loop that uses epoll and nothing else. |
544 | |
581 | |
… | |
… | |
546 | if (!epoller) |
583 | if (!epoller) |
547 | fatal ("no epoll found here, maybe it hides under your chair"); |
584 | fatal ("no epoll found here, maybe it hides under your chair"); |
548 | |
585 | |
549 | =item ev_default_destroy () |
586 | =item ev_default_destroy () |
550 | |
587 | |
551 | Destroys the default loop again (frees all memory and kernel state |
588 | Destroys the default loop (frees all memory and kernel state etc.). None |
552 | etc.). None of the active event watchers will be stopped in the normal |
589 | of the active event watchers will be stopped in the normal sense, so |
553 | sense, so e.g. C<ev_is_active> might still return true. It is your |
590 | e.g. C<ev_is_active> might still return true. It is your responsibility to |
554 | responsibility to either stop all watchers cleanly yourself I<before> |
591 | either stop all watchers cleanly yourself I<before> calling this function, |
555 | calling this function, or cope with the fact afterwards (which is usually |
592 | or cope with the fact afterwards (which is usually the easiest thing, you |
556 | the easiest thing, you can just ignore the watchers and/or C<free ()> them |
593 | can just ignore the watchers and/or C<free ()> them for example). |
557 | for example). |
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|
558 | |
594 | |
559 | Note that certain global state, such as signal state (and installed signal |
595 | Note that certain global state, such as signal state (and installed signal |
560 | handlers), will not be freed by this function, and related watchers (such |
596 | handlers), will not be freed by this function, and related watchers (such |
561 | as signal and child watchers) would need to be stopped manually. |
597 | as signal and child watchers) would need to be stopped manually. |
562 | |
598 | |
563 | In general it is not advisable to call this function except in the |
599 | In general it is not advisable to call this function except in the |
564 | rare occasion where you really need to free e.g. the signal handling |
600 | rare occasion where you really need to free e.g. the signal handling |
565 | pipe fds. If you need dynamically allocated loops it is better to use |
601 | pipe fds. If you need dynamically allocated loops it is better to use |
566 | C<ev_loop_new> and C<ev_loop_destroy>). |
602 | C<ev_loop_new> and C<ev_loop_destroy>. |
567 | |
603 | |
568 | =item ev_loop_destroy (loop) |
604 | =item ev_loop_destroy (loop) |
569 | |
605 | |
570 | Like C<ev_default_destroy>, but destroys an event loop created by an |
606 | Like C<ev_default_destroy>, but destroys an event loop created by an |
571 | earlier call to C<ev_loop_new>. |
607 | earlier call to C<ev_loop_new>. |
572 | |
608 | |
573 | =item ev_default_fork () |
609 | =item ev_default_fork () |
574 | |
610 | |
575 | This function sets a flag that causes subsequent C<ev_loop> iterations |
611 | This function sets a flag that causes subsequent C<ev_run> iterations |
576 | to reinitialise the kernel state for backends that have one. Despite the |
612 | to reinitialise the kernel state for backends that have one. Despite the |
577 | name, you can call it anytime, but it makes most sense after forking, in |
613 | name, you can call it anytime, but it makes most sense after forking, in |
578 | the child process (or both child and parent, but that again makes little |
614 | the child process (or both child and parent, but that again makes little |
579 | sense). You I<must> call it in the child before using any of the libev |
615 | sense). You I<must> call it in the child before using any of the libev |
580 | functions, and it will only take effect at the next C<ev_loop> iteration. |
616 | functions, and it will only take effect at the next C<ev_run> iteration. |
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617 | |
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618 | Again, you I<have> to call it on I<any> loop that you want to re-use after |
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619 | a fork, I<even if you do not plan to use the loop in the parent>. This is |
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620 | because some kernel interfaces *cough* I<kqueue> *cough* do funny things |
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621 | during fork. |
581 | |
622 | |
582 | On the other hand, you only need to call this function in the child |
623 | On the other hand, you only need to call this function in the child |
583 | process if and only if you want to use the event library in the child. If |
624 | process if and only if you want to use the event loop in the child. If |
584 | you just fork+exec, you don't have to call it at all. |
625 | you just fork+exec or create a new loop in the child, you don't have to |
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|
626 | call it at all (in fact, C<epoll> is so badly broken that it makes a |
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627 | difference, but libev will usually detect this case on its own and do a |
|
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628 | costly reset of the backend). |
585 | |
629 | |
586 | The function itself is quite fast and it's usually not a problem to call |
630 | The function itself is quite fast and it's usually not a problem to call |
587 | it just in case after a fork. To make this easy, the function will fit in |
631 | it just in case after a fork. To make this easy, the function will fit in |
588 | quite nicely into a call to C<pthread_atfork>: |
632 | quite nicely into a call to C<pthread_atfork>: |
589 | |
633 | |
… | |
… | |
591 | |
635 | |
592 | =item ev_loop_fork (loop) |
636 | =item ev_loop_fork (loop) |
593 | |
637 | |
594 | Like C<ev_default_fork>, but acts on an event loop created by |
638 | Like C<ev_default_fork>, but acts on an event loop created by |
595 | C<ev_loop_new>. Yes, you have to call this on every allocated event loop |
639 | C<ev_loop_new>. Yes, you have to call this on every allocated event loop |
596 | after fork that you want to re-use in the child, and how you do this is |
640 | after fork that you want to re-use in the child, and how you keep track of |
597 | entirely your own problem. |
641 | them is entirely your own problem. |
598 | |
642 | |
599 | =item int ev_is_default_loop (loop) |
643 | =item int ev_is_default_loop (loop) |
600 | |
644 | |
601 | Returns true when the given loop is, in fact, the default loop, and false |
645 | Returns true when the given loop is, in fact, the default loop, and false |
602 | otherwise. |
646 | otherwise. |
603 | |
647 | |
604 | =item unsigned int ev_loop_count (loop) |
648 | =item unsigned int ev_iteration (loop) |
605 | |
649 | |
606 | Returns the count of loop iterations for the loop, which is identical to |
650 | Returns the current iteration count for the event loop, which is identical |
607 | the number of times libev did poll for new events. It starts at C<0> and |
651 | to the number of times libev did poll for new events. It starts at C<0> |
608 | happily wraps around with enough iterations. |
652 | and happily wraps around with enough iterations. |
609 | |
653 | |
610 | This value can sometimes be useful as a generation counter of sorts (it |
654 | This value can sometimes be useful as a generation counter of sorts (it |
611 | "ticks" the number of loop iterations), as it roughly corresponds with |
655 | "ticks" the number of loop iterations), as it roughly corresponds with |
612 | C<ev_prepare> and C<ev_check> calls. |
656 | C<ev_prepare> and C<ev_check> calls - and is incremented between the |
|
|
657 | prepare and check phases. |
|
|
658 | |
|
|
659 | =item unsigned int ev_depth (loop) |
|
|
660 | |
|
|
661 | Returns the number of times C<ev_run> was entered minus the number of |
|
|
662 | times C<ev_run> was exited, in other words, the recursion depth. |
|
|
663 | |
|
|
664 | Outside C<ev_run>, this number is zero. In a callback, this number is |
|
|
665 | C<1>, unless C<ev_run> was invoked recursively (or from another thread), |
|
|
666 | in which case it is higher. |
|
|
667 | |
|
|
668 | Leaving C<ev_run> abnormally (setjmp/longjmp, cancelling the thread |
|
|
669 | etc.), doesn't count as "exit" - consider this as a hint to avoid such |
|
|
670 | ungentleman-like behaviour unless it's really convenient. |
613 | |
671 | |
614 | =item unsigned int ev_backend (loop) |
672 | =item unsigned int ev_backend (loop) |
615 | |
673 | |
616 | Returns one of the C<EVBACKEND_*> flags indicating the event backend in |
674 | Returns one of the C<EVBACKEND_*> flags indicating the event backend in |
617 | use. |
675 | use. |
… | |
… | |
626 | |
684 | |
627 | =item ev_now_update (loop) |
685 | =item ev_now_update (loop) |
628 | |
686 | |
629 | Establishes the current time by querying the kernel, updating the time |
687 | Establishes the current time by querying the kernel, updating the time |
630 | returned by C<ev_now ()> in the progress. This is a costly operation and |
688 | returned by C<ev_now ()> in the progress. This is a costly operation and |
631 | is usually done automatically within C<ev_loop ()>. |
689 | is usually done automatically within C<ev_run ()>. |
632 | |
690 | |
633 | This function is rarely useful, but when some event callback runs for a |
691 | This function is rarely useful, but when some event callback runs for a |
634 | very long time without entering the event loop, updating libev's idea of |
692 | very long time without entering the event loop, updating libev's idea of |
635 | the current time is a good idea. |
693 | the current time is a good idea. |
636 | |
694 | |
637 | See also "The special problem of time updates" in the C<ev_timer> section. |
695 | See also L<The special problem of time updates> in the C<ev_timer> section. |
638 | |
696 | |
639 | =item ev_suspend (loop) |
697 | =item ev_suspend (loop) |
640 | |
698 | |
641 | =item ev_resume (loop) |
699 | =item ev_resume (loop) |
642 | |
700 | |
643 | These two functions suspend and resume a loop, for use when the loop is |
701 | These two functions suspend and resume an event loop, for use when the |
644 | not used for a while and timeouts should not be processed. |
702 | loop is not used for a while and timeouts should not be processed. |
645 | |
703 | |
646 | A typical use case would be an interactive program such as a game: When |
704 | A typical use case would be an interactive program such as a game: When |
647 | the user presses C<^Z> to suspend the game and resumes it an hour later it |
705 | the user presses C<^Z> to suspend the game and resumes it an hour later it |
648 | would be best to handle timeouts as if no time had actually passed while |
706 | would be best to handle timeouts as if no time had actually passed while |
649 | the program was suspended. This can be achieved by calling C<ev_suspend> |
707 | the program was suspended. This can be achieved by calling C<ev_suspend> |
… | |
… | |
651 | C<ev_resume> directly afterwards to resume timer processing. |
709 | C<ev_resume> directly afterwards to resume timer processing. |
652 | |
710 | |
653 | Effectively, all C<ev_timer> watchers will be delayed by the time spend |
711 | Effectively, all C<ev_timer> watchers will be delayed by the time spend |
654 | between C<ev_suspend> and C<ev_resume>, and all C<ev_periodic> watchers |
712 | between C<ev_suspend> and C<ev_resume>, and all C<ev_periodic> watchers |
655 | will be rescheduled (that is, they will lose any events that would have |
713 | will be rescheduled (that is, they will lose any events that would have |
656 | occured while suspended). |
714 | occurred while suspended). |
657 | |
715 | |
658 | After calling C<ev_suspend> you B<must not> call I<any> function on the |
716 | After calling C<ev_suspend> you B<must not> call I<any> function on the |
659 | given loop other than C<ev_resume>, and you B<must not> call C<ev_resume> |
717 | given loop other than C<ev_resume>, and you B<must not> call C<ev_resume> |
660 | without a previous call to C<ev_suspend>. |
718 | without a previous call to C<ev_suspend>. |
661 | |
719 | |
662 | Calling C<ev_suspend>/C<ev_resume> has the side effect of updating the |
720 | Calling C<ev_suspend>/C<ev_resume> has the side effect of updating the |
663 | event loop time (see C<ev_now_update>). |
721 | event loop time (see C<ev_now_update>). |
664 | |
722 | |
665 | =item ev_loop (loop, int flags) |
723 | =item ev_run (loop, int flags) |
666 | |
724 | |
667 | Finally, this is it, the event handler. This function usually is called |
725 | Finally, this is it, the event handler. This function usually is called |
668 | after you initialised all your watchers and you want to start handling |
726 | after you have initialised all your watchers and you want to start |
669 | events. |
727 | handling events. It will ask the operating system for any new events, call |
|
|
728 | the watcher callbacks, an then repeat the whole process indefinitely: This |
|
|
729 | is why event loops are called I<loops>. |
670 | |
730 | |
671 | If the flags argument is specified as C<0>, it will not return until |
731 | If the flags argument is specified as C<0>, it will keep handling events |
672 | either no event watchers are active anymore or C<ev_unloop> was called. |
732 | until either no event watchers are active anymore or C<ev_break> was |
|
|
733 | called. |
673 | |
734 | |
674 | Please note that an explicit C<ev_unloop> is usually better than |
735 | Please note that an explicit C<ev_break> is usually better than |
675 | relying on all watchers to be stopped when deciding when a program has |
736 | relying on all watchers to be stopped when deciding when a program has |
676 | finished (especially in interactive programs), but having a program |
737 | finished (especially in interactive programs), but having a program |
677 | that automatically loops as long as it has to and no longer by virtue |
738 | that automatically loops as long as it has to and no longer by virtue |
678 | of relying on its watchers stopping correctly, that is truly a thing of |
739 | of relying on its watchers stopping correctly, that is truly a thing of |
679 | beauty. |
740 | beauty. |
680 | |
741 | |
681 | A flags value of C<EVLOOP_NONBLOCK> will look for new events, will handle |
742 | A flags value of C<EVRUN_NOWAIT> will look for new events, will handle |
682 | those events and any already outstanding ones, but will not block your |
743 | those events and any already outstanding ones, but will not wait and |
683 | process in case there are no events and will return after one iteration of |
744 | block your process in case there are no events and will return after one |
684 | the loop. |
745 | iteration of the loop. This is sometimes useful to poll and handle new |
|
|
746 | events while doing lengthy calculations, to keep the program responsive. |
685 | |
747 | |
686 | A flags value of C<EVLOOP_ONESHOT> will look for new events (waiting if |
748 | A flags value of C<EVRUN_ONCE> will look for new events (waiting if |
687 | necessary) and will handle those and any already outstanding ones. It |
749 | necessary) and will handle those and any already outstanding ones. It |
688 | will block your process until at least one new event arrives (which could |
750 | will block your process until at least one new event arrives (which could |
689 | be an event internal to libev itself, so there is no guarantee that a |
751 | be an event internal to libev itself, so there is no guarantee that a |
690 | user-registered callback will be called), and will return after one |
752 | user-registered callback will be called), and will return after one |
691 | iteration of the loop. |
753 | iteration of the loop. |
692 | |
754 | |
693 | This is useful if you are waiting for some external event in conjunction |
755 | This is useful if you are waiting for some external event in conjunction |
694 | with something not expressible using other libev watchers (i.e. "roll your |
756 | with something not expressible using other libev watchers (i.e. "roll your |
695 | own C<ev_loop>"). However, a pair of C<ev_prepare>/C<ev_check> watchers is |
757 | own C<ev_run>"). However, a pair of C<ev_prepare>/C<ev_check> watchers is |
696 | usually a better approach for this kind of thing. |
758 | usually a better approach for this kind of thing. |
697 | |
759 | |
698 | Here are the gory details of what C<ev_loop> does: |
760 | Here are the gory details of what C<ev_run> does: |
699 | |
761 | |
|
|
762 | - Increment loop depth. |
|
|
763 | - Reset the ev_break status. |
700 | - Before the first iteration, call any pending watchers. |
764 | - Before the first iteration, call any pending watchers. |
|
|
765 | LOOP: |
701 | * If EVFLAG_FORKCHECK was used, check for a fork. |
766 | - If EVFLAG_FORKCHECK was used, check for a fork. |
702 | - If a fork was detected (by any means), queue and call all fork watchers. |
767 | - If a fork was detected (by any means), queue and call all fork watchers. |
703 | - Queue and call all prepare watchers. |
768 | - Queue and call all prepare watchers. |
|
|
769 | - If ev_break was called, goto FINISH. |
704 | - If we have been forked, detach and recreate the kernel state |
770 | - If we have been forked, detach and recreate the kernel state |
705 | as to not disturb the other process. |
771 | as to not disturb the other process. |
706 | - Update the kernel state with all outstanding changes. |
772 | - Update the kernel state with all outstanding changes. |
707 | - Update the "event loop time" (ev_now ()). |
773 | - Update the "event loop time" (ev_now ()). |
708 | - Calculate for how long to sleep or block, if at all |
774 | - Calculate for how long to sleep or block, if at all |
709 | (active idle watchers, EVLOOP_NONBLOCK or not having |
775 | (active idle watchers, EVRUN_NOWAIT or not having |
710 | any active watchers at all will result in not sleeping). |
776 | any active watchers at all will result in not sleeping). |
711 | - Sleep if the I/O and timer collect interval say so. |
777 | - Sleep if the I/O and timer collect interval say so. |
|
|
778 | - Increment loop iteration counter. |
712 | - Block the process, waiting for any events. |
779 | - Block the process, waiting for any events. |
713 | - Queue all outstanding I/O (fd) events. |
780 | - Queue all outstanding I/O (fd) events. |
714 | - Update the "event loop time" (ev_now ()), and do time jump adjustments. |
781 | - Update the "event loop time" (ev_now ()), and do time jump adjustments. |
715 | - Queue all expired timers. |
782 | - Queue all expired timers. |
716 | - Queue all expired periodics. |
783 | - Queue all expired periodics. |
717 | - Unless any events are pending now, queue all idle watchers. |
784 | - Queue all idle watchers with priority higher than that of pending events. |
718 | - Queue all check watchers. |
785 | - Queue all check watchers. |
719 | - Call all queued watchers in reverse order (i.e. check watchers first). |
786 | - Call all queued watchers in reverse order (i.e. check watchers first). |
720 | Signals and child watchers are implemented as I/O watchers, and will |
787 | Signals and child watchers are implemented as I/O watchers, and will |
721 | be handled here by queueing them when their watcher gets executed. |
788 | be handled here by queueing them when their watcher gets executed. |
722 | - If ev_unloop has been called, or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
789 | - If ev_break has been called, or EVRUN_ONCE or EVRUN_NOWAIT |
723 | were used, or there are no active watchers, return, otherwise |
790 | were used, or there are no active watchers, goto FINISH, otherwise |
724 | continue with step *. |
791 | continue with step LOOP. |
|
|
792 | FINISH: |
|
|
793 | - Reset the ev_break status iff it was EVBREAK_ONE. |
|
|
794 | - Decrement the loop depth. |
|
|
795 | - Return. |
725 | |
796 | |
726 | Example: Queue some jobs and then loop until no events are outstanding |
797 | Example: Queue some jobs and then loop until no events are outstanding |
727 | anymore. |
798 | anymore. |
728 | |
799 | |
729 | ... queue jobs here, make sure they register event watchers as long |
800 | ... queue jobs here, make sure they register event watchers as long |
730 | ... as they still have work to do (even an idle watcher will do..) |
801 | ... as they still have work to do (even an idle watcher will do..) |
731 | ev_loop (my_loop, 0); |
802 | ev_run (my_loop, 0); |
732 | ... jobs done or somebody called unloop. yeah! |
803 | ... jobs done or somebody called unloop. yeah! |
733 | |
804 | |
734 | =item ev_unloop (loop, how) |
805 | =item ev_break (loop, how) |
735 | |
806 | |
736 | Can be used to make a call to C<ev_loop> return early (but only after it |
807 | Can be used to make a call to C<ev_run> return early (but only after it |
737 | has processed all outstanding events). The C<how> argument must be either |
808 | has processed all outstanding events). The C<how> argument must be either |
738 | C<EVUNLOOP_ONE>, which will make the innermost C<ev_loop> call return, or |
809 | C<EVBREAK_ONE>, which will make the innermost C<ev_run> call return, or |
739 | C<EVUNLOOP_ALL>, which will make all nested C<ev_loop> calls return. |
810 | C<EVBREAK_ALL>, which will make all nested C<ev_run> calls return. |
740 | |
811 | |
741 | This "unloop state" will be cleared when entering C<ev_loop> again. |
812 | This "unloop state" will be cleared when entering C<ev_run> again. |
742 | |
813 | |
743 | It is safe to call C<ev_unloop> from otuside any C<ev_loop> calls. |
814 | It is safe to call C<ev_break> from outside any C<ev_run> calls. ##TODO## |
744 | |
815 | |
745 | =item ev_ref (loop) |
816 | =item ev_ref (loop) |
746 | |
817 | |
747 | =item ev_unref (loop) |
818 | =item ev_unref (loop) |
748 | |
819 | |
749 | Ref/unref can be used to add or remove a reference count on the event |
820 | Ref/unref can be used to add or remove a reference count on the event |
750 | loop: Every watcher keeps one reference, and as long as the reference |
821 | loop: Every watcher keeps one reference, and as long as the reference |
751 | count is nonzero, C<ev_loop> will not return on its own. |
822 | count is nonzero, C<ev_run> will not return on its own. |
752 | |
823 | |
753 | If you have a watcher you never unregister that should not keep C<ev_loop> |
824 | This is useful when you have a watcher that you never intend to |
754 | from returning, call ev_unref() after starting, and ev_ref() before |
825 | unregister, but that nevertheless should not keep C<ev_run> from |
|
|
826 | returning. In such a case, call C<ev_unref> after starting, and C<ev_ref> |
755 | stopping it. |
827 | before stopping it. |
756 | |
828 | |
757 | As an example, libev itself uses this for its internal signal pipe: It |
829 | As an example, libev itself uses this for its internal signal pipe: It |
758 | is not visible to the libev user and should not keep C<ev_loop> from |
830 | is not visible to the libev user and should not keep C<ev_run> from |
759 | exiting if no event watchers registered by it are active. It is also an |
831 | exiting if no event watchers registered by it are active. It is also an |
760 | excellent way to do this for generic recurring timers or from within |
832 | excellent way to do this for generic recurring timers or from within |
761 | third-party libraries. Just remember to I<unref after start> and I<ref |
833 | third-party libraries. Just remember to I<unref after start> and I<ref |
762 | before stop> (but only if the watcher wasn't active before, or was active |
834 | before stop> (but only if the watcher wasn't active before, or was active |
763 | before, respectively. Note also that libev might stop watchers itself |
835 | before, respectively. Note also that libev might stop watchers itself |
764 | (e.g. non-repeating timers) in which case you have to C<ev_ref> |
836 | (e.g. non-repeating timers) in which case you have to C<ev_ref> |
765 | in the callback). |
837 | in the callback). |
766 | |
838 | |
767 | Example: Create a signal watcher, but keep it from keeping C<ev_loop> |
839 | Example: Create a signal watcher, but keep it from keeping C<ev_run> |
768 | running when nothing else is active. |
840 | running when nothing else is active. |
769 | |
841 | |
770 | ev_signal exitsig; |
842 | ev_signal exitsig; |
771 | ev_signal_init (&exitsig, sig_cb, SIGINT); |
843 | ev_signal_init (&exitsig, sig_cb, SIGINT); |
772 | ev_signal_start (loop, &exitsig); |
844 | ev_signal_start (loop, &exitsig); |
… | |
… | |
799 | |
871 | |
800 | By setting a higher I<io collect interval> you allow libev to spend more |
872 | By setting a higher I<io collect interval> you allow libev to spend more |
801 | time collecting I/O events, so you can handle more events per iteration, |
873 | time collecting I/O events, so you can handle more events per iteration, |
802 | at the cost of increasing latency. Timeouts (both C<ev_periodic> and |
874 | at the cost of increasing latency. Timeouts (both C<ev_periodic> and |
803 | C<ev_timer>) will be not affected. Setting this to a non-null value will |
875 | C<ev_timer>) will be not affected. Setting this to a non-null value will |
804 | introduce an additional C<ev_sleep ()> call into most loop iterations. |
876 | introduce an additional C<ev_sleep ()> call into most loop iterations. The |
|
|
877 | sleep time ensures that libev will not poll for I/O events more often then |
|
|
878 | once per this interval, on average. |
805 | |
879 | |
806 | Likewise, by setting a higher I<timeout collect interval> you allow libev |
880 | Likewise, by setting a higher I<timeout collect interval> you allow libev |
807 | to spend more time collecting timeouts, at the expense of increased |
881 | to spend more time collecting timeouts, at the expense of increased |
808 | latency/jitter/inexactness (the watcher callback will be called |
882 | latency/jitter/inexactness (the watcher callback will be called |
809 | later). C<ev_io> watchers will not be affected. Setting this to a non-null |
883 | later). C<ev_io> watchers will not be affected. Setting this to a non-null |
… | |
… | |
811 | |
885 | |
812 | Many (busy) programs can usually benefit by setting the I/O collect |
886 | Many (busy) programs can usually benefit by setting the I/O collect |
813 | interval to a value near C<0.1> or so, which is often enough for |
887 | interval to a value near C<0.1> or so, which is often enough for |
814 | interactive servers (of course not for games), likewise for timeouts. It |
888 | interactive servers (of course not for games), likewise for timeouts. It |
815 | usually doesn't make much sense to set it to a lower value than C<0.01>, |
889 | usually doesn't make much sense to set it to a lower value than C<0.01>, |
816 | as this approaches the timing granularity of most systems. |
890 | as this approaches the timing granularity of most systems. Note that if |
|
|
891 | you do transactions with the outside world and you can't increase the |
|
|
892 | parallelity, then this setting will limit your transaction rate (if you |
|
|
893 | need to poll once per transaction and the I/O collect interval is 0.01, |
|
|
894 | then you can't do more than 100 transactions per second). |
817 | |
895 | |
818 | Setting the I<timeout collect interval> can improve the opportunity for |
896 | Setting the I<timeout collect interval> can improve the opportunity for |
819 | saving power, as the program will "bundle" timer callback invocations that |
897 | saving power, as the program will "bundle" timer callback invocations that |
820 | are "near" in time together, by delaying some, thus reducing the number of |
898 | are "near" in time together, by delaying some, thus reducing the number of |
821 | times the process sleeps and wakes up again. Another useful technique to |
899 | times the process sleeps and wakes up again. Another useful technique to |
822 | reduce iterations/wake-ups is to use C<ev_periodic> watchers and make sure |
900 | reduce iterations/wake-ups is to use C<ev_periodic> watchers and make sure |
823 | they fire on, say, one-second boundaries only. |
901 | they fire on, say, one-second boundaries only. |
824 | |
902 | |
|
|
903 | Example: we only need 0.1s timeout granularity, and we wish not to poll |
|
|
904 | more often than 100 times per second: |
|
|
905 | |
|
|
906 | ev_set_timeout_collect_interval (EV_DEFAULT_UC_ 0.1); |
|
|
907 | ev_set_io_collect_interval (EV_DEFAULT_UC_ 0.01); |
|
|
908 | |
|
|
909 | =item ev_invoke_pending (loop) |
|
|
910 | |
|
|
911 | This call will simply invoke all pending watchers while resetting their |
|
|
912 | pending state. Normally, C<ev_run> does this automatically when required, |
|
|
913 | but when overriding the invoke callback this call comes handy. |
|
|
914 | |
|
|
915 | =item int ev_pending_count (loop) |
|
|
916 | |
|
|
917 | Returns the number of pending watchers - zero indicates that no watchers |
|
|
918 | are pending. |
|
|
919 | |
|
|
920 | =item ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(EV_P)) |
|
|
921 | |
|
|
922 | This overrides the invoke pending functionality of the loop: Instead of |
|
|
923 | invoking all pending watchers when there are any, C<ev_run> will call |
|
|
924 | this callback instead. This is useful, for example, when you want to |
|
|
925 | invoke the actual watchers inside another context (another thread etc.). |
|
|
926 | |
|
|
927 | If you want to reset the callback, use C<ev_invoke_pending> as new |
|
|
928 | callback. |
|
|
929 | |
|
|
930 | =item ev_set_loop_release_cb (loop, void (*release)(EV_P), void (*acquire)(EV_P)) |
|
|
931 | |
|
|
932 | Sometimes you want to share the same loop between multiple threads. This |
|
|
933 | can be done relatively simply by putting mutex_lock/unlock calls around |
|
|
934 | each call to a libev function. |
|
|
935 | |
|
|
936 | However, C<ev_run> can run an indefinite time, so it is not feasible |
|
|
937 | to wait for it to return. One way around this is to wake up the event |
|
|
938 | loop via C<ev_break> and C<av_async_send>, another way is to set these |
|
|
939 | I<release> and I<acquire> callbacks on the loop. |
|
|
940 | |
|
|
941 | When set, then C<release> will be called just before the thread is |
|
|
942 | suspended waiting for new events, and C<acquire> is called just |
|
|
943 | afterwards. |
|
|
944 | |
|
|
945 | Ideally, C<release> will just call your mutex_unlock function, and |
|
|
946 | C<acquire> will just call the mutex_lock function again. |
|
|
947 | |
|
|
948 | While event loop modifications are allowed between invocations of |
|
|
949 | C<release> and C<acquire> (that's their only purpose after all), no |
|
|
950 | modifications done will affect the event loop, i.e. adding watchers will |
|
|
951 | have no effect on the set of file descriptors being watched, or the time |
|
|
952 | waited. Use an C<ev_async> watcher to wake up C<ev_run> when you want it |
|
|
953 | to take note of any changes you made. |
|
|
954 | |
|
|
955 | In theory, threads executing C<ev_run> will be async-cancel safe between |
|
|
956 | invocations of C<release> and C<acquire>. |
|
|
957 | |
|
|
958 | See also the locking example in the C<THREADS> section later in this |
|
|
959 | document. |
|
|
960 | |
|
|
961 | =item ev_set_userdata (loop, void *data) |
|
|
962 | |
|
|
963 | =item ev_userdata (loop) |
|
|
964 | |
|
|
965 | Set and retrieve a single C<void *> associated with a loop. When |
|
|
966 | C<ev_set_userdata> has never been called, then C<ev_userdata> returns |
|
|
967 | C<0.> |
|
|
968 | |
|
|
969 | These two functions can be used to associate arbitrary data with a loop, |
|
|
970 | and are intended solely for the C<invoke_pending_cb>, C<release> and |
|
|
971 | C<acquire> callbacks described above, but of course can be (ab-)used for |
|
|
972 | any other purpose as well. |
|
|
973 | |
825 | =item ev_loop_verify (loop) |
974 | =item ev_verify (loop) |
826 | |
975 | |
827 | This function only does something when C<EV_VERIFY> support has been |
976 | This function only does something when C<EV_VERIFY> support has been |
828 | compiled in, which is the default for non-minimal builds. It tries to go |
977 | compiled in, which is the default for non-minimal builds. It tries to go |
829 | through all internal structures and checks them for validity. If anything |
978 | through all internal structures and checks them for validity. If anything |
830 | is found to be inconsistent, it will print an error message to standard |
979 | is found to be inconsistent, it will print an error message to standard |
… | |
… | |
848 | become readable, you would create an C<ev_io> watcher for that: |
997 | become readable, you would create an C<ev_io> watcher for that: |
849 | |
998 | |
850 | static void my_cb (struct ev_loop *loop, ev_io *w, int revents) |
999 | static void my_cb (struct ev_loop *loop, ev_io *w, int revents) |
851 | { |
1000 | { |
852 | ev_io_stop (w); |
1001 | ev_io_stop (w); |
853 | ev_unloop (loop, EVUNLOOP_ALL); |
1002 | ev_break (loop, EVBREAK_ALL); |
854 | } |
1003 | } |
855 | |
1004 | |
856 | struct ev_loop *loop = ev_default_loop (0); |
1005 | struct ev_loop *loop = ev_default_loop (0); |
857 | |
1006 | |
858 | ev_io stdin_watcher; |
1007 | ev_io stdin_watcher; |
859 | |
1008 | |
860 | ev_init (&stdin_watcher, my_cb); |
1009 | ev_init (&stdin_watcher, my_cb); |
861 | ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ); |
1010 | ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ); |
862 | ev_io_start (loop, &stdin_watcher); |
1011 | ev_io_start (loop, &stdin_watcher); |
863 | |
1012 | |
864 | ev_loop (loop, 0); |
1013 | ev_run (loop, 0); |
865 | |
1014 | |
866 | As you can see, you are responsible for allocating the memory for your |
1015 | As you can see, you are responsible for allocating the memory for your |
867 | watcher structures (and it is I<usually> a bad idea to do this on the |
1016 | watcher structures (and it is I<usually> a bad idea to do this on the |
868 | stack). |
1017 | stack). |
869 | |
1018 | |
… | |
… | |
905 | =item C<EV_WRITE> |
1054 | =item C<EV_WRITE> |
906 | |
1055 | |
907 | The file descriptor in the C<ev_io> watcher has become readable and/or |
1056 | The file descriptor in the C<ev_io> watcher has become readable and/or |
908 | writable. |
1057 | writable. |
909 | |
1058 | |
910 | =item C<EV_TIMEOUT> |
1059 | =item C<EV_TIMER> |
911 | |
1060 | |
912 | The C<ev_timer> watcher has timed out. |
1061 | The C<ev_timer> watcher has timed out. |
913 | |
1062 | |
914 | =item C<EV_PERIODIC> |
1063 | =item C<EV_PERIODIC> |
915 | |
1064 | |
… | |
… | |
933 | |
1082 | |
934 | =item C<EV_PREPARE> |
1083 | =item C<EV_PREPARE> |
935 | |
1084 | |
936 | =item C<EV_CHECK> |
1085 | =item C<EV_CHECK> |
937 | |
1086 | |
938 | All C<ev_prepare> watchers are invoked just I<before> C<ev_loop> starts |
1087 | All C<ev_prepare> watchers are invoked just I<before> C<ev_run> starts |
939 | to gather new events, and all C<ev_check> watchers are invoked just after |
1088 | to gather new events, and all C<ev_check> watchers are invoked just after |
940 | C<ev_loop> has gathered them, but before it invokes any callbacks for any |
1089 | C<ev_run> has gathered them, but before it invokes any callbacks for any |
941 | received events. Callbacks of both watcher types can start and stop as |
1090 | received events. Callbacks of both watcher types can start and stop as |
942 | many watchers as they want, and all of them will be taken into account |
1091 | many watchers as they want, and all of them will be taken into account |
943 | (for example, a C<ev_prepare> watcher might start an idle watcher to keep |
1092 | (for example, a C<ev_prepare> watcher might start an idle watcher to keep |
944 | C<ev_loop> from blocking). |
1093 | C<ev_run> from blocking). |
945 | |
1094 | |
946 | =item C<EV_EMBED> |
1095 | =item C<EV_EMBED> |
947 | |
1096 | |
948 | The embedded event loop specified in the C<ev_embed> watcher needs attention. |
1097 | The embedded event loop specified in the C<ev_embed> watcher needs attention. |
949 | |
1098 | |
… | |
… | |
1005 | |
1154 | |
1006 | ev_io w; |
1155 | ev_io w; |
1007 | ev_init (&w, my_cb); |
1156 | ev_init (&w, my_cb); |
1008 | ev_io_set (&w, STDIN_FILENO, EV_READ); |
1157 | ev_io_set (&w, STDIN_FILENO, EV_READ); |
1009 | |
1158 | |
1010 | =item C<ev_TYPE_set> (ev_TYPE *, [args]) |
1159 | =item C<ev_TYPE_set> (ev_TYPE *watcher, [args]) |
1011 | |
1160 | |
1012 | This macro initialises the type-specific parts of a watcher. You need to |
1161 | This macro initialises the type-specific parts of a watcher. You need to |
1013 | call C<ev_init> at least once before you call this macro, but you can |
1162 | call C<ev_init> at least once before you call this macro, but you can |
1014 | call C<ev_TYPE_set> any number of times. You must not, however, call this |
1163 | call C<ev_TYPE_set> any number of times. You must not, however, call this |
1015 | macro on a watcher that is active (it can be pending, however, which is a |
1164 | macro on a watcher that is active (it can be pending, however, which is a |
… | |
… | |
1028 | |
1177 | |
1029 | Example: Initialise and set an C<ev_io> watcher in one step. |
1178 | Example: Initialise and set an C<ev_io> watcher in one step. |
1030 | |
1179 | |
1031 | ev_io_init (&w, my_cb, STDIN_FILENO, EV_READ); |
1180 | ev_io_init (&w, my_cb, STDIN_FILENO, EV_READ); |
1032 | |
1181 | |
1033 | =item C<ev_TYPE_start> (loop *, ev_TYPE *watcher) |
1182 | =item C<ev_TYPE_start> (loop, ev_TYPE *watcher) |
1034 | |
1183 | |
1035 | Starts (activates) the given watcher. Only active watchers will receive |
1184 | Starts (activates) the given watcher. Only active watchers will receive |
1036 | events. If the watcher is already active nothing will happen. |
1185 | events. If the watcher is already active nothing will happen. |
1037 | |
1186 | |
1038 | Example: Start the C<ev_io> watcher that is being abused as example in this |
1187 | Example: Start the C<ev_io> watcher that is being abused as example in this |
1039 | whole section. |
1188 | whole section. |
1040 | |
1189 | |
1041 | ev_io_start (EV_DEFAULT_UC, &w); |
1190 | ev_io_start (EV_DEFAULT_UC, &w); |
1042 | |
1191 | |
1043 | =item C<ev_TYPE_stop> (loop *, ev_TYPE *watcher) |
1192 | =item C<ev_TYPE_stop> (loop, ev_TYPE *watcher) |
1044 | |
1193 | |
1045 | Stops the given watcher if active, and clears the pending status (whether |
1194 | Stops the given watcher if active, and clears the pending status (whether |
1046 | the watcher was active or not). |
1195 | the watcher was active or not). |
1047 | |
1196 | |
1048 | It is possible that stopped watchers are pending - for example, |
1197 | It is possible that stopped watchers are pending - for example, |
… | |
… | |
1073 | =item ev_cb_set (ev_TYPE *watcher, callback) |
1222 | =item ev_cb_set (ev_TYPE *watcher, callback) |
1074 | |
1223 | |
1075 | Change the callback. You can change the callback at virtually any time |
1224 | Change the callback. You can change the callback at virtually any time |
1076 | (modulo threads). |
1225 | (modulo threads). |
1077 | |
1226 | |
1078 | =item ev_set_priority (ev_TYPE *watcher, priority) |
1227 | =item ev_set_priority (ev_TYPE *watcher, int priority) |
1079 | |
1228 | |
1080 | =item int ev_priority (ev_TYPE *watcher) |
1229 | =item int ev_priority (ev_TYPE *watcher) |
1081 | |
1230 | |
1082 | Set and query the priority of the watcher. The priority is a small |
1231 | Set and query the priority of the watcher. The priority is a small |
1083 | integer between C<EV_MAXPRI> (default: C<2>) and C<EV_MINPRI> |
1232 | integer between C<EV_MAXPRI> (default: C<2>) and C<EV_MINPRI> |
1084 | (default: C<-2>). Pending watchers with higher priority will be invoked |
1233 | (default: C<-2>). Pending watchers with higher priority will be invoked |
1085 | before watchers with lower priority, but priority will not keep watchers |
1234 | before watchers with lower priority, but priority will not keep watchers |
1086 | from being executed (except for C<ev_idle> watchers). |
1235 | from being executed (except for C<ev_idle> watchers). |
1087 | |
1236 | |
1088 | This means that priorities are I<only> used for ordering callback |
|
|
1089 | invocation after new events have been received. This is useful, for |
|
|
1090 | example, to reduce latency after idling, or more often, to bind two |
|
|
1091 | watchers on the same event and make sure one is called first. |
|
|
1092 | |
|
|
1093 | If you need to suppress invocation when higher priority events are pending |
1237 | If you need to suppress invocation when higher priority events are pending |
1094 | you need to look at C<ev_idle> watchers, which provide this functionality. |
1238 | you need to look at C<ev_idle> watchers, which provide this functionality. |
1095 | |
1239 | |
1096 | You I<must not> change the priority of a watcher as long as it is active or |
1240 | You I<must not> change the priority of a watcher as long as it is active or |
1097 | pending. |
1241 | pending. |
1098 | |
|
|
1099 | The default priority used by watchers when no priority has been set is |
|
|
1100 | always C<0>, which is supposed to not be too high and not be too low :). |
|
|
1101 | |
1242 | |
1102 | Setting a priority outside the range of C<EV_MINPRI> to C<EV_MAXPRI> is |
1243 | Setting a priority outside the range of C<EV_MINPRI> to C<EV_MAXPRI> is |
1103 | fine, as long as you do not mind that the priority value you query might |
1244 | fine, as long as you do not mind that the priority value you query might |
1104 | or might not have been clamped to the valid range. |
1245 | or might not have been clamped to the valid range. |
|
|
1246 | |
|
|
1247 | The default priority used by watchers when no priority has been set is |
|
|
1248 | always C<0>, which is supposed to not be too high and not be too low :). |
|
|
1249 | |
|
|
1250 | See L<WATCHER PRIORITY MODELS>, below, for a more thorough treatment of |
|
|
1251 | priorities. |
1105 | |
1252 | |
1106 | =item ev_invoke (loop, ev_TYPE *watcher, int revents) |
1253 | =item ev_invoke (loop, ev_TYPE *watcher, int revents) |
1107 | |
1254 | |
1108 | Invoke the C<watcher> with the given C<loop> and C<revents>. Neither |
1255 | Invoke the C<watcher> with the given C<loop> and C<revents>. Neither |
1109 | C<loop> nor C<revents> need to be valid as long as the watcher callback |
1256 | C<loop> nor C<revents> need to be valid as long as the watcher callback |
… | |
… | |
1116 | returns its C<revents> bitset (as if its callback was invoked). If the |
1263 | returns its C<revents> bitset (as if its callback was invoked). If the |
1117 | watcher isn't pending it does nothing and returns C<0>. |
1264 | watcher isn't pending it does nothing and returns C<0>. |
1118 | |
1265 | |
1119 | Sometimes it can be useful to "poll" a watcher instead of waiting for its |
1266 | Sometimes it can be useful to "poll" a watcher instead of waiting for its |
1120 | callback to be invoked, which can be accomplished with this function. |
1267 | callback to be invoked, which can be accomplished with this function. |
|
|
1268 | |
|
|
1269 | =item ev_feed_event (loop, ev_TYPE *watcher, int revents) |
|
|
1270 | |
|
|
1271 | Feeds the given event set into the event loop, as if the specified event |
|
|
1272 | had happened for the specified watcher (which must be a pointer to an |
|
|
1273 | initialised but not necessarily started event watcher). Obviously you must |
|
|
1274 | not free the watcher as long as it has pending events. |
|
|
1275 | |
|
|
1276 | Stopping the watcher, letting libev invoke it, or calling |
|
|
1277 | C<ev_clear_pending> will clear the pending event, even if the watcher was |
|
|
1278 | not started in the first place. |
|
|
1279 | |
|
|
1280 | See also C<ev_feed_fd_event> and C<ev_feed_signal_event> for related |
|
|
1281 | functions that do not need a watcher. |
1121 | |
1282 | |
1122 | =back |
1283 | =back |
1123 | |
1284 | |
1124 | |
1285 | |
1125 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
1286 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
… | |
… | |
1174 | #include <stddef.h> |
1335 | #include <stddef.h> |
1175 | |
1336 | |
1176 | static void |
1337 | static void |
1177 | t1_cb (EV_P_ ev_timer *w, int revents) |
1338 | t1_cb (EV_P_ ev_timer *w, int revents) |
1178 | { |
1339 | { |
1179 | struct my_biggy big = (struct my_biggy * |
1340 | struct my_biggy big = (struct my_biggy *) |
1180 | (((char *)w) - offsetof (struct my_biggy, t1)); |
1341 | (((char *)w) - offsetof (struct my_biggy, t1)); |
1181 | } |
1342 | } |
1182 | |
1343 | |
1183 | static void |
1344 | static void |
1184 | t2_cb (EV_P_ ev_timer *w, int revents) |
1345 | t2_cb (EV_P_ ev_timer *w, int revents) |
1185 | { |
1346 | { |
1186 | struct my_biggy big = (struct my_biggy * |
1347 | struct my_biggy big = (struct my_biggy *) |
1187 | (((char *)w) - offsetof (struct my_biggy, t2)); |
1348 | (((char *)w) - offsetof (struct my_biggy, t2)); |
1188 | } |
1349 | } |
|
|
1350 | |
|
|
1351 | =head2 WATCHER PRIORITY MODELS |
|
|
1352 | |
|
|
1353 | Many event loops support I<watcher priorities>, which are usually small |
|
|
1354 | integers that influence the ordering of event callback invocation |
|
|
1355 | between watchers in some way, all else being equal. |
|
|
1356 | |
|
|
1357 | In libev, Watcher priorities can be set using C<ev_set_priority>. See its |
|
|
1358 | description for the more technical details such as the actual priority |
|
|
1359 | range. |
|
|
1360 | |
|
|
1361 | There are two common ways how these these priorities are being interpreted |
|
|
1362 | by event loops: |
|
|
1363 | |
|
|
1364 | In the more common lock-out model, higher priorities "lock out" invocation |
|
|
1365 | of lower priority watchers, which means as long as higher priority |
|
|
1366 | watchers receive events, lower priority watchers are not being invoked. |
|
|
1367 | |
|
|
1368 | The less common only-for-ordering model uses priorities solely to order |
|
|
1369 | callback invocation within a single event loop iteration: Higher priority |
|
|
1370 | watchers are invoked before lower priority ones, but they all get invoked |
|
|
1371 | before polling for new events. |
|
|
1372 | |
|
|
1373 | Libev uses the second (only-for-ordering) model for all its watchers |
|
|
1374 | except for idle watchers (which use the lock-out model). |
|
|
1375 | |
|
|
1376 | The rationale behind this is that implementing the lock-out model for |
|
|
1377 | watchers is not well supported by most kernel interfaces, and most event |
|
|
1378 | libraries will just poll for the same events again and again as long as |
|
|
1379 | their callbacks have not been executed, which is very inefficient in the |
|
|
1380 | common case of one high-priority watcher locking out a mass of lower |
|
|
1381 | priority ones. |
|
|
1382 | |
|
|
1383 | Static (ordering) priorities are most useful when you have two or more |
|
|
1384 | watchers handling the same resource: a typical usage example is having an |
|
|
1385 | C<ev_io> watcher to receive data, and an associated C<ev_timer> to handle |
|
|
1386 | timeouts. Under load, data might be received while the program handles |
|
|
1387 | other jobs, but since timers normally get invoked first, the timeout |
|
|
1388 | handler will be executed before checking for data. In that case, giving |
|
|
1389 | the timer a lower priority than the I/O watcher ensures that I/O will be |
|
|
1390 | handled first even under adverse conditions (which is usually, but not |
|
|
1391 | always, what you want). |
|
|
1392 | |
|
|
1393 | Since idle watchers use the "lock-out" model, meaning that idle watchers |
|
|
1394 | will only be executed when no same or higher priority watchers have |
|
|
1395 | received events, they can be used to implement the "lock-out" model when |
|
|
1396 | required. |
|
|
1397 | |
|
|
1398 | For example, to emulate how many other event libraries handle priorities, |
|
|
1399 | you can associate an C<ev_idle> watcher to each such watcher, and in |
|
|
1400 | the normal watcher callback, you just start the idle watcher. The real |
|
|
1401 | processing is done in the idle watcher callback. This causes libev to |
|
|
1402 | continuously poll and process kernel event data for the watcher, but when |
|
|
1403 | the lock-out case is known to be rare (which in turn is rare :), this is |
|
|
1404 | workable. |
|
|
1405 | |
|
|
1406 | Usually, however, the lock-out model implemented that way will perform |
|
|
1407 | miserably under the type of load it was designed to handle. In that case, |
|
|
1408 | it might be preferable to stop the real watcher before starting the |
|
|
1409 | idle watcher, so the kernel will not have to process the event in case |
|
|
1410 | the actual processing will be delayed for considerable time. |
|
|
1411 | |
|
|
1412 | Here is an example of an I/O watcher that should run at a strictly lower |
|
|
1413 | priority than the default, and which should only process data when no |
|
|
1414 | other events are pending: |
|
|
1415 | |
|
|
1416 | ev_idle idle; // actual processing watcher |
|
|
1417 | ev_io io; // actual event watcher |
|
|
1418 | |
|
|
1419 | static void |
|
|
1420 | io_cb (EV_P_ ev_io *w, int revents) |
|
|
1421 | { |
|
|
1422 | // stop the I/O watcher, we received the event, but |
|
|
1423 | // are not yet ready to handle it. |
|
|
1424 | ev_io_stop (EV_A_ w); |
|
|
1425 | |
|
|
1426 | // start the idle watcher to handle the actual event. |
|
|
1427 | // it will not be executed as long as other watchers |
|
|
1428 | // with the default priority are receiving events. |
|
|
1429 | ev_idle_start (EV_A_ &idle); |
|
|
1430 | } |
|
|
1431 | |
|
|
1432 | static void |
|
|
1433 | idle_cb (EV_P_ ev_idle *w, int revents) |
|
|
1434 | { |
|
|
1435 | // actual processing |
|
|
1436 | read (STDIN_FILENO, ...); |
|
|
1437 | |
|
|
1438 | // have to start the I/O watcher again, as |
|
|
1439 | // we have handled the event |
|
|
1440 | ev_io_start (EV_P_ &io); |
|
|
1441 | } |
|
|
1442 | |
|
|
1443 | // initialisation |
|
|
1444 | ev_idle_init (&idle, idle_cb); |
|
|
1445 | ev_io_init (&io, io_cb, STDIN_FILENO, EV_READ); |
|
|
1446 | ev_io_start (EV_DEFAULT_ &io); |
|
|
1447 | |
|
|
1448 | In the "real" world, it might also be beneficial to start a timer, so that |
|
|
1449 | low-priority connections can not be locked out forever under load. This |
|
|
1450 | enables your program to keep a lower latency for important connections |
|
|
1451 | during short periods of high load, while not completely locking out less |
|
|
1452 | important ones. |
1189 | |
1453 | |
1190 | |
1454 | |
1191 | =head1 WATCHER TYPES |
1455 | =head1 WATCHER TYPES |
1192 | |
1456 | |
1193 | This section describes each watcher in detail, but will not repeat |
1457 | This section describes each watcher in detail, but will not repeat |
… | |
… | |
1219 | descriptors to non-blocking mode is also usually a good idea (but not |
1483 | descriptors to non-blocking mode is also usually a good idea (but not |
1220 | required if you know what you are doing). |
1484 | required if you know what you are doing). |
1221 | |
1485 | |
1222 | If you cannot use non-blocking mode, then force the use of a |
1486 | If you cannot use non-blocking mode, then force the use of a |
1223 | known-to-be-good backend (at the time of this writing, this includes only |
1487 | known-to-be-good backend (at the time of this writing, this includes only |
1224 | C<EVBACKEND_SELECT> and C<EVBACKEND_POLL>). |
1488 | C<EVBACKEND_SELECT> and C<EVBACKEND_POLL>). The same applies to file |
|
|
1489 | descriptors for which non-blocking operation makes no sense (such as |
|
|
1490 | files) - libev doesn't guarantee any specific behaviour in that case. |
1225 | |
1491 | |
1226 | Another thing you have to watch out for is that it is quite easy to |
1492 | Another thing you have to watch out for is that it is quite easy to |
1227 | receive "spurious" readiness notifications, that is your callback might |
1493 | receive "spurious" readiness notifications, that is your callback might |
1228 | be called with C<EV_READ> but a subsequent C<read>(2) will actually block |
1494 | be called with C<EV_READ> but a subsequent C<read>(2) will actually block |
1229 | because there is no data. Not only are some backends known to create a |
1495 | because there is no data. Not only are some backends known to create a |
… | |
… | |
1294 | |
1560 | |
1295 | So when you encounter spurious, unexplained daemon exits, make sure you |
1561 | So when you encounter spurious, unexplained daemon exits, make sure you |
1296 | ignore SIGPIPE (and maybe make sure you log the exit status of your daemon |
1562 | ignore SIGPIPE (and maybe make sure you log the exit status of your daemon |
1297 | somewhere, as that would have given you a big clue). |
1563 | somewhere, as that would have given you a big clue). |
1298 | |
1564 | |
|
|
1565 | =head3 The special problem of accept()ing when you can't |
|
|
1566 | |
|
|
1567 | Many implementations of the POSIX C<accept> function (for example, |
|
|
1568 | found in post-2004 Linux) have the peculiar behaviour of not removing a |
|
|
1569 | connection from the pending queue in all error cases. |
|
|
1570 | |
|
|
1571 | For example, larger servers often run out of file descriptors (because |
|
|
1572 | of resource limits), causing C<accept> to fail with C<ENFILE> but not |
|
|
1573 | rejecting the connection, leading to libev signalling readiness on |
|
|
1574 | the next iteration again (the connection still exists after all), and |
|
|
1575 | typically causing the program to loop at 100% CPU usage. |
|
|
1576 | |
|
|
1577 | Unfortunately, the set of errors that cause this issue differs between |
|
|
1578 | operating systems, there is usually little the app can do to remedy the |
|
|
1579 | situation, and no known thread-safe method of removing the connection to |
|
|
1580 | cope with overload is known (to me). |
|
|
1581 | |
|
|
1582 | One of the easiest ways to handle this situation is to just ignore it |
|
|
1583 | - when the program encounters an overload, it will just loop until the |
|
|
1584 | situation is over. While this is a form of busy waiting, no OS offers an |
|
|
1585 | event-based way to handle this situation, so it's the best one can do. |
|
|
1586 | |
|
|
1587 | A better way to handle the situation is to log any errors other than |
|
|
1588 | C<EAGAIN> and C<EWOULDBLOCK>, making sure not to flood the log with such |
|
|
1589 | messages, and continue as usual, which at least gives the user an idea of |
|
|
1590 | what could be wrong ("raise the ulimit!"). For extra points one could stop |
|
|
1591 | the C<ev_io> watcher on the listening fd "for a while", which reduces CPU |
|
|
1592 | usage. |
|
|
1593 | |
|
|
1594 | If your program is single-threaded, then you could also keep a dummy file |
|
|
1595 | descriptor for overload situations (e.g. by opening F</dev/null>), and |
|
|
1596 | when you run into C<ENFILE> or C<EMFILE>, close it, run C<accept>, |
|
|
1597 | close that fd, and create a new dummy fd. This will gracefully refuse |
|
|
1598 | clients under typical overload conditions. |
|
|
1599 | |
|
|
1600 | The last way to handle it is to simply log the error and C<exit>, as |
|
|
1601 | is often done with C<malloc> failures, but this results in an easy |
|
|
1602 | opportunity for a DoS attack. |
1299 | |
1603 | |
1300 | =head3 Watcher-Specific Functions |
1604 | =head3 Watcher-Specific Functions |
1301 | |
1605 | |
1302 | =over 4 |
1606 | =over 4 |
1303 | |
1607 | |
… | |
… | |
1335 | ... |
1639 | ... |
1336 | struct ev_loop *loop = ev_default_init (0); |
1640 | struct ev_loop *loop = ev_default_init (0); |
1337 | ev_io stdin_readable; |
1641 | ev_io stdin_readable; |
1338 | ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ); |
1642 | ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ); |
1339 | ev_io_start (loop, &stdin_readable); |
1643 | ev_io_start (loop, &stdin_readable); |
1340 | ev_loop (loop, 0); |
1644 | ev_run (loop, 0); |
1341 | |
1645 | |
1342 | |
1646 | |
1343 | =head2 C<ev_timer> - relative and optionally repeating timeouts |
1647 | =head2 C<ev_timer> - relative and optionally repeating timeouts |
1344 | |
1648 | |
1345 | Timer watchers are simple relative timers that generate an event after a |
1649 | Timer watchers are simple relative timers that generate an event after a |
… | |
… | |
1350 | year, it will still time out after (roughly) one hour. "Roughly" because |
1654 | year, it will still time out after (roughly) one hour. "Roughly" because |
1351 | detecting time jumps is hard, and some inaccuracies are unavoidable (the |
1655 | detecting time jumps is hard, and some inaccuracies are unavoidable (the |
1352 | monotonic clock option helps a lot here). |
1656 | monotonic clock option helps a lot here). |
1353 | |
1657 | |
1354 | The callback is guaranteed to be invoked only I<after> its timeout has |
1658 | The callback is guaranteed to be invoked only I<after> its timeout has |
1355 | passed. If multiple timers become ready during the same loop iteration |
1659 | passed (not I<at>, so on systems with very low-resolution clocks this |
1356 | then the ones with earlier time-out values are invoked before ones with |
1660 | might introduce a small delay). If multiple timers become ready during the |
1357 | later time-out values (but this is no longer true when a callback calls |
1661 | same loop iteration then the ones with earlier time-out values are invoked |
1358 | C<ev_loop> recursively). |
1662 | before ones of the same priority with later time-out values (but this is |
|
|
1663 | no longer true when a callback calls C<ev_run> recursively). |
1359 | |
1664 | |
1360 | =head3 Be smart about timeouts |
1665 | =head3 Be smart about timeouts |
1361 | |
1666 | |
1362 | Many real-world problems involve some kind of timeout, usually for error |
1667 | Many real-world problems involve some kind of timeout, usually for error |
1363 | recovery. A typical example is an HTTP request - if the other side hangs, |
1668 | recovery. A typical example is an HTTP request - if the other side hangs, |
… | |
… | |
1407 | C<after> argument to C<ev_timer_set>, and only ever use the C<repeat> |
1712 | C<after> argument to C<ev_timer_set>, and only ever use the C<repeat> |
1408 | member and C<ev_timer_again>. |
1713 | member and C<ev_timer_again>. |
1409 | |
1714 | |
1410 | At start: |
1715 | At start: |
1411 | |
1716 | |
1412 | ev_timer_init (timer, callback); |
1717 | ev_init (timer, callback); |
1413 | timer->repeat = 60.; |
1718 | timer->repeat = 60.; |
1414 | ev_timer_again (loop, timer); |
1719 | ev_timer_again (loop, timer); |
1415 | |
1720 | |
1416 | Each time there is some activity: |
1721 | Each time there is some activity: |
1417 | |
1722 | |
… | |
… | |
1449 | ev_tstamp timeout = last_activity + 60.; |
1754 | ev_tstamp timeout = last_activity + 60.; |
1450 | |
1755 | |
1451 | // if last_activity + 60. is older than now, we did time out |
1756 | // if last_activity + 60. is older than now, we did time out |
1452 | if (timeout < now) |
1757 | if (timeout < now) |
1453 | { |
1758 | { |
1454 | // timeout occured, take action |
1759 | // timeout occurred, take action |
1455 | } |
1760 | } |
1456 | else |
1761 | else |
1457 | { |
1762 | { |
1458 | // callback was invoked, but there was some activity, re-arm |
1763 | // callback was invoked, but there was some activity, re-arm |
1459 | // the watcher to fire in last_activity + 60, which is |
1764 | // the watcher to fire in last_activity + 60, which is |
… | |
… | |
1479 | |
1784 | |
1480 | To start the timer, simply initialise the watcher and set C<last_activity> |
1785 | To start the timer, simply initialise the watcher and set C<last_activity> |
1481 | to the current time (meaning we just have some activity :), then call the |
1786 | to the current time (meaning we just have some activity :), then call the |
1482 | callback, which will "do the right thing" and start the timer: |
1787 | callback, which will "do the right thing" and start the timer: |
1483 | |
1788 | |
1484 | ev_timer_init (timer, callback); |
1789 | ev_init (timer, callback); |
1485 | last_activity = ev_now (loop); |
1790 | last_activity = ev_now (loop); |
1486 | callback (loop, timer, EV_TIMEOUT); |
1791 | callback (loop, timer, EV_TIMER); |
1487 | |
1792 | |
1488 | And when there is some activity, simply store the current time in |
1793 | And when there is some activity, simply store the current time in |
1489 | C<last_activity>, no libev calls at all: |
1794 | C<last_activity>, no libev calls at all: |
1490 | |
1795 | |
1491 | last_actiivty = ev_now (loop); |
1796 | last_activity = ev_now (loop); |
1492 | |
1797 | |
1493 | This technique is slightly more complex, but in most cases where the |
1798 | This technique is slightly more complex, but in most cases where the |
1494 | time-out is unlikely to be triggered, much more efficient. |
1799 | time-out is unlikely to be triggered, much more efficient. |
1495 | |
1800 | |
1496 | Changing the timeout is trivial as well (if it isn't hard-coded in the |
1801 | Changing the timeout is trivial as well (if it isn't hard-coded in the |
… | |
… | |
1534 | |
1839 | |
1535 | =head3 The special problem of time updates |
1840 | =head3 The special problem of time updates |
1536 | |
1841 | |
1537 | Establishing the current time is a costly operation (it usually takes at |
1842 | Establishing the current time is a costly operation (it usually takes at |
1538 | least two system calls): EV therefore updates its idea of the current |
1843 | least two system calls): EV therefore updates its idea of the current |
1539 | time only before and after C<ev_loop> collects new events, which causes a |
1844 | time only before and after C<ev_run> collects new events, which causes a |
1540 | growing difference between C<ev_now ()> and C<ev_time ()> when handling |
1845 | growing difference between C<ev_now ()> and C<ev_time ()> when handling |
1541 | lots of events in one iteration. |
1846 | lots of events in one iteration. |
1542 | |
1847 | |
1543 | The relative timeouts are calculated relative to the C<ev_now ()> |
1848 | The relative timeouts are calculated relative to the C<ev_now ()> |
1544 | time. This is usually the right thing as this timestamp refers to the time |
1849 | time. This is usually the right thing as this timestamp refers to the time |
… | |
… | |
1550 | |
1855 | |
1551 | If the event loop is suspended for a long time, you can also force an |
1856 | If the event loop is suspended for a long time, you can also force an |
1552 | update of the time returned by C<ev_now ()> by calling C<ev_now_update |
1857 | update of the time returned by C<ev_now ()> by calling C<ev_now_update |
1553 | ()>. |
1858 | ()>. |
1554 | |
1859 | |
|
|
1860 | =head3 The special problems of suspended animation |
|
|
1861 | |
|
|
1862 | When you leave the server world it is quite customary to hit machines that |
|
|
1863 | can suspend/hibernate - what happens to the clocks during such a suspend? |
|
|
1864 | |
|
|
1865 | Some quick tests made with a Linux 2.6.28 indicate that a suspend freezes |
|
|
1866 | all processes, while the clocks (C<times>, C<CLOCK_MONOTONIC>) continue |
|
|
1867 | to run until the system is suspended, but they will not advance while the |
|
|
1868 | system is suspended. That means, on resume, it will be as if the program |
|
|
1869 | was frozen for a few seconds, but the suspend time will not be counted |
|
|
1870 | towards C<ev_timer> when a monotonic clock source is used. The real time |
|
|
1871 | clock advanced as expected, but if it is used as sole clocksource, then a |
|
|
1872 | long suspend would be detected as a time jump by libev, and timers would |
|
|
1873 | be adjusted accordingly. |
|
|
1874 | |
|
|
1875 | I would not be surprised to see different behaviour in different between |
|
|
1876 | operating systems, OS versions or even different hardware. |
|
|
1877 | |
|
|
1878 | The other form of suspend (job control, or sending a SIGSTOP) will see a |
|
|
1879 | time jump in the monotonic clocks and the realtime clock. If the program |
|
|
1880 | is suspended for a very long time, and monotonic clock sources are in use, |
|
|
1881 | then you can expect C<ev_timer>s to expire as the full suspension time |
|
|
1882 | will be counted towards the timers. When no monotonic clock source is in |
|
|
1883 | use, then libev will again assume a timejump and adjust accordingly. |
|
|
1884 | |
|
|
1885 | It might be beneficial for this latter case to call C<ev_suspend> |
|
|
1886 | and C<ev_resume> in code that handles C<SIGTSTP>, to at least get |
|
|
1887 | deterministic behaviour in this case (you can do nothing against |
|
|
1888 | C<SIGSTOP>). |
|
|
1889 | |
1555 | =head3 Watcher-Specific Functions and Data Members |
1890 | =head3 Watcher-Specific Functions and Data Members |
1556 | |
1891 | |
1557 | =over 4 |
1892 | =over 4 |
1558 | |
1893 | |
1559 | =item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat) |
1894 | =item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat) |
… | |
… | |
1582 | If the timer is started but non-repeating, stop it (as if it timed out). |
1917 | If the timer is started but non-repeating, stop it (as if it timed out). |
1583 | |
1918 | |
1584 | If the timer is repeating, either start it if necessary (with the |
1919 | If the timer is repeating, either start it if necessary (with the |
1585 | C<repeat> value), or reset the running timer to the C<repeat> value. |
1920 | C<repeat> value), or reset the running timer to the C<repeat> value. |
1586 | |
1921 | |
1587 | This sounds a bit complicated, see "Be smart about timeouts", above, for a |
1922 | This sounds a bit complicated, see L<Be smart about timeouts>, above, for a |
1588 | usage example. |
1923 | usage example. |
|
|
1924 | |
|
|
1925 | =item ev_tstamp ev_timer_remaining (loop, ev_timer *) |
|
|
1926 | |
|
|
1927 | Returns the remaining time until a timer fires. If the timer is active, |
|
|
1928 | then this time is relative to the current event loop time, otherwise it's |
|
|
1929 | the timeout value currently configured. |
|
|
1930 | |
|
|
1931 | That is, after an C<ev_timer_set (w, 5, 7)>, C<ev_timer_remaining> returns |
|
|
1932 | C<5>. When the timer is started and one second passes, C<ev_timer_remaining> |
|
|
1933 | will return C<4>. When the timer expires and is restarted, it will return |
|
|
1934 | roughly C<7> (likely slightly less as callback invocation takes some time, |
|
|
1935 | too), and so on. |
1589 | |
1936 | |
1590 | =item ev_tstamp repeat [read-write] |
1937 | =item ev_tstamp repeat [read-write] |
1591 | |
1938 | |
1592 | The current C<repeat> value. Will be used each time the watcher times out |
1939 | The current C<repeat> value. Will be used each time the watcher times out |
1593 | or C<ev_timer_again> is called, and determines the next timeout (if any), |
1940 | or C<ev_timer_again> is called, and determines the next timeout (if any), |
… | |
… | |
1619 | } |
1966 | } |
1620 | |
1967 | |
1621 | ev_timer mytimer; |
1968 | ev_timer mytimer; |
1622 | ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */ |
1969 | ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */ |
1623 | ev_timer_again (&mytimer); /* start timer */ |
1970 | ev_timer_again (&mytimer); /* start timer */ |
1624 | ev_loop (loop, 0); |
1971 | ev_run (loop, 0); |
1625 | |
1972 | |
1626 | // and in some piece of code that gets executed on any "activity": |
1973 | // and in some piece of code that gets executed on any "activity": |
1627 | // reset the timeout to start ticking again at 10 seconds |
1974 | // reset the timeout to start ticking again at 10 seconds |
1628 | ev_timer_again (&mytimer); |
1975 | ev_timer_again (&mytimer); |
1629 | |
1976 | |
… | |
… | |
1655 | |
2002 | |
1656 | As with timers, the callback is guaranteed to be invoked only when the |
2003 | As with timers, the callback is guaranteed to be invoked only when the |
1657 | point in time where it is supposed to trigger has passed. If multiple |
2004 | point in time where it is supposed to trigger has passed. If multiple |
1658 | timers become ready during the same loop iteration then the ones with |
2005 | timers become ready during the same loop iteration then the ones with |
1659 | earlier time-out values are invoked before ones with later time-out values |
2006 | earlier time-out values are invoked before ones with later time-out values |
1660 | (but this is no longer true when a callback calls C<ev_loop> recursively). |
2007 | (but this is no longer true when a callback calls C<ev_run> recursively). |
1661 | |
2008 | |
1662 | =head3 Watcher-Specific Functions and Data Members |
2009 | =head3 Watcher-Specific Functions and Data Members |
1663 | |
2010 | |
1664 | =over 4 |
2011 | =over 4 |
1665 | |
2012 | |
… | |
… | |
1793 | Example: Call a callback every hour, or, more precisely, whenever the |
2140 | Example: Call a callback every hour, or, more precisely, whenever the |
1794 | system time is divisible by 3600. The callback invocation times have |
2141 | system time is divisible by 3600. The callback invocation times have |
1795 | potentially a lot of jitter, but good long-term stability. |
2142 | potentially a lot of jitter, but good long-term stability. |
1796 | |
2143 | |
1797 | static void |
2144 | static void |
1798 | clock_cb (struct ev_loop *loop, ev_io *w, int revents) |
2145 | clock_cb (struct ev_loop *loop, ev_periodic *w, int revents) |
1799 | { |
2146 | { |
1800 | ... its now a full hour (UTC, or TAI or whatever your clock follows) |
2147 | ... its now a full hour (UTC, or TAI or whatever your clock follows) |
1801 | } |
2148 | } |
1802 | |
2149 | |
1803 | ev_periodic hourly_tick; |
2150 | ev_periodic hourly_tick; |
… | |
… | |
1829 | Signal watchers will trigger an event when the process receives a specific |
2176 | Signal watchers will trigger an event when the process receives a specific |
1830 | signal one or more times. Even though signals are very asynchronous, libev |
2177 | signal one or more times. Even though signals are very asynchronous, libev |
1831 | will try it's best to deliver signals synchronously, i.e. as part of the |
2178 | will try it's best to deliver signals synchronously, i.e. as part of the |
1832 | normal event processing, like any other event. |
2179 | normal event processing, like any other event. |
1833 | |
2180 | |
1834 | If you want signals asynchronously, just use C<sigaction> as you would |
2181 | If you want signals to be delivered truly asynchronously, just use |
1835 | do without libev and forget about sharing the signal. You can even use |
2182 | C<sigaction> as you would do without libev and forget about sharing |
1836 | C<ev_async> from a signal handler to synchronously wake up an event loop. |
2183 | the signal. You can even use C<ev_async> from a signal handler to |
|
|
2184 | synchronously wake up an event loop. |
1837 | |
2185 | |
1838 | You can configure as many watchers as you like per signal. Only when the |
2186 | You can configure as many watchers as you like for the same signal, but |
|
|
2187 | only within the same loop, i.e. you can watch for C<SIGINT> in your |
|
|
2188 | default loop and for C<SIGIO> in another loop, but you cannot watch for |
|
|
2189 | C<SIGINT> in both the default loop and another loop at the same time. At |
|
|
2190 | the moment, C<SIGCHLD> is permanently tied to the default loop. |
|
|
2191 | |
1839 | first watcher gets started will libev actually register a signal handler |
2192 | When the first watcher gets started will libev actually register something |
1840 | with the kernel (thus it coexists with your own signal handlers as long as |
2193 | with the kernel (thus it coexists with your own signal handlers as long as |
1841 | you don't register any with libev for the same signal). Similarly, when |
2194 | you don't register any with libev for the same signal). |
1842 | the last signal watcher for a signal is stopped, libev will reset the |
|
|
1843 | signal handler to SIG_DFL (regardless of what it was set to before). |
|
|
1844 | |
2195 | |
1845 | If possible and supported, libev will install its handlers with |
2196 | If possible and supported, libev will install its handlers with |
1846 | C<SA_RESTART> behaviour enabled, so system calls should not be unduly |
2197 | C<SA_RESTART> (or equivalent) behaviour enabled, so system calls should |
1847 | interrupted. If you have a problem with system calls getting interrupted by |
2198 | not be unduly interrupted. If you have a problem with system calls getting |
1848 | signals you can block all signals in an C<ev_check> watcher and unblock |
2199 | interrupted by signals you can block all signals in an C<ev_check> watcher |
1849 | them in an C<ev_prepare> watcher. |
2200 | and unblock them in an C<ev_prepare> watcher. |
|
|
2201 | |
|
|
2202 | =head3 The special problem of inheritance over fork/execve/pthread_create |
|
|
2203 | |
|
|
2204 | Both the signal mask (C<sigprocmask>) and the signal disposition |
|
|
2205 | (C<sigaction>) are unspecified after starting a signal watcher (and after |
|
|
2206 | stopping it again), that is, libev might or might not block the signal, |
|
|
2207 | and might or might not set or restore the installed signal handler. |
|
|
2208 | |
|
|
2209 | While this does not matter for the signal disposition (libev never |
|
|
2210 | sets signals to C<SIG_IGN>, so handlers will be reset to C<SIG_DFL> on |
|
|
2211 | C<execve>), this matters for the signal mask: many programs do not expect |
|
|
2212 | certain signals to be blocked. |
|
|
2213 | |
|
|
2214 | This means that before calling C<exec> (from the child) you should reset |
|
|
2215 | the signal mask to whatever "default" you expect (all clear is a good |
|
|
2216 | choice usually). |
|
|
2217 | |
|
|
2218 | The simplest way to ensure that the signal mask is reset in the child is |
|
|
2219 | to install a fork handler with C<pthread_atfork> that resets it. That will |
|
|
2220 | catch fork calls done by libraries (such as the libc) as well. |
|
|
2221 | |
|
|
2222 | In current versions of libev, the signal will not be blocked indefinitely |
|
|
2223 | unless you use the C<signalfd> API (C<EV_SIGNALFD>). While this reduces |
|
|
2224 | the window of opportunity for problems, it will not go away, as libev |
|
|
2225 | I<has> to modify the signal mask, at least temporarily. |
|
|
2226 | |
|
|
2227 | So I can't stress this enough: I<If you do not reset your signal mask when |
|
|
2228 | you expect it to be empty, you have a race condition in your code>. This |
|
|
2229 | is not a libev-specific thing, this is true for most event libraries. |
1850 | |
2230 | |
1851 | =head3 Watcher-Specific Functions and Data Members |
2231 | =head3 Watcher-Specific Functions and Data Members |
1852 | |
2232 | |
1853 | =over 4 |
2233 | =over 4 |
1854 | |
2234 | |
… | |
… | |
1870 | Example: Try to exit cleanly on SIGINT. |
2250 | Example: Try to exit cleanly on SIGINT. |
1871 | |
2251 | |
1872 | static void |
2252 | static void |
1873 | sigint_cb (struct ev_loop *loop, ev_signal *w, int revents) |
2253 | sigint_cb (struct ev_loop *loop, ev_signal *w, int revents) |
1874 | { |
2254 | { |
1875 | ev_unloop (loop, EVUNLOOP_ALL); |
2255 | ev_break (loop, EVBREAK_ALL); |
1876 | } |
2256 | } |
1877 | |
2257 | |
1878 | ev_signal signal_watcher; |
2258 | ev_signal signal_watcher; |
1879 | ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
2259 | ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
1880 | ev_signal_start (loop, &signal_watcher); |
2260 | ev_signal_start (loop, &signal_watcher); |
… | |
… | |
1886 | some child status changes (most typically when a child of yours dies or |
2266 | some child status changes (most typically when a child of yours dies or |
1887 | exits). It is permissible to install a child watcher I<after> the child |
2267 | exits). It is permissible to install a child watcher I<after> the child |
1888 | has been forked (which implies it might have already exited), as long |
2268 | has been forked (which implies it might have already exited), as long |
1889 | as the event loop isn't entered (or is continued from a watcher), i.e., |
2269 | as the event loop isn't entered (or is continued from a watcher), i.e., |
1890 | forking and then immediately registering a watcher for the child is fine, |
2270 | forking and then immediately registering a watcher for the child is fine, |
1891 | but forking and registering a watcher a few event loop iterations later is |
2271 | but forking and registering a watcher a few event loop iterations later or |
1892 | not. |
2272 | in the next callback invocation is not. |
1893 | |
2273 | |
1894 | Only the default event loop is capable of handling signals, and therefore |
2274 | Only the default event loop is capable of handling signals, and therefore |
1895 | you can only register child watchers in the default event loop. |
2275 | you can only register child watchers in the default event loop. |
1896 | |
2276 | |
|
|
2277 | Due to some design glitches inside libev, child watchers will always be |
|
|
2278 | handled at maximum priority (their priority is set to C<EV_MAXPRI> by |
|
|
2279 | libev) |
|
|
2280 | |
1897 | =head3 Process Interaction |
2281 | =head3 Process Interaction |
1898 | |
2282 | |
1899 | Libev grabs C<SIGCHLD> as soon as the default event loop is |
2283 | Libev grabs C<SIGCHLD> as soon as the default event loop is |
1900 | initialised. This is necessary to guarantee proper behaviour even if |
2284 | initialised. This is necessary to guarantee proper behaviour even if the |
1901 | the first child watcher is started after the child exits. The occurrence |
2285 | first child watcher is started after the child exits. The occurrence |
1902 | of C<SIGCHLD> is recorded asynchronously, but child reaping is done |
2286 | of C<SIGCHLD> is recorded asynchronously, but child reaping is done |
1903 | synchronously as part of the event loop processing. Libev always reaps all |
2287 | synchronously as part of the event loop processing. Libev always reaps all |
1904 | children, even ones not watched. |
2288 | children, even ones not watched. |
1905 | |
2289 | |
1906 | =head3 Overriding the Built-In Processing |
2290 | =head3 Overriding the Built-In Processing |
… | |
… | |
1916 | =head3 Stopping the Child Watcher |
2300 | =head3 Stopping the Child Watcher |
1917 | |
2301 | |
1918 | Currently, the child watcher never gets stopped, even when the |
2302 | Currently, the child watcher never gets stopped, even when the |
1919 | child terminates, so normally one needs to stop the watcher in the |
2303 | child terminates, so normally one needs to stop the watcher in the |
1920 | callback. Future versions of libev might stop the watcher automatically |
2304 | callback. Future versions of libev might stop the watcher automatically |
1921 | when a child exit is detected. |
2305 | when a child exit is detected (calling C<ev_child_stop> twice is not a |
|
|
2306 | problem). |
1922 | |
2307 | |
1923 | =head3 Watcher-Specific Functions and Data Members |
2308 | =head3 Watcher-Specific Functions and Data Members |
1924 | |
2309 | |
1925 | =over 4 |
2310 | =over 4 |
1926 | |
2311 | |
… | |
… | |
2252 | // no longer anything immediate to do. |
2637 | // no longer anything immediate to do. |
2253 | } |
2638 | } |
2254 | |
2639 | |
2255 | ev_idle *idle_watcher = malloc (sizeof (ev_idle)); |
2640 | ev_idle *idle_watcher = malloc (sizeof (ev_idle)); |
2256 | ev_idle_init (idle_watcher, idle_cb); |
2641 | ev_idle_init (idle_watcher, idle_cb); |
2257 | ev_idle_start (loop, idle_cb); |
2642 | ev_idle_start (loop, idle_watcher); |
2258 | |
2643 | |
2259 | |
2644 | |
2260 | =head2 C<ev_prepare> and C<ev_check> - customise your event loop! |
2645 | =head2 C<ev_prepare> and C<ev_check> - customise your event loop! |
2261 | |
2646 | |
2262 | Prepare and check watchers are usually (but not always) used in pairs: |
2647 | Prepare and check watchers are usually (but not always) used in pairs: |
2263 | prepare watchers get invoked before the process blocks and check watchers |
2648 | prepare watchers get invoked before the process blocks and check watchers |
2264 | afterwards. |
2649 | afterwards. |
2265 | |
2650 | |
2266 | You I<must not> call C<ev_loop> or similar functions that enter |
2651 | You I<must not> call C<ev_run> or similar functions that enter |
2267 | the current event loop from either C<ev_prepare> or C<ev_check> |
2652 | the current event loop from either C<ev_prepare> or C<ev_check> |
2268 | watchers. Other loops than the current one are fine, however. The |
2653 | watchers. Other loops than the current one are fine, however. The |
2269 | rationale behind this is that you do not need to check for recursion in |
2654 | rationale behind this is that you do not need to check for recursion in |
2270 | those watchers, i.e. the sequence will always be C<ev_prepare>, blocking, |
2655 | those watchers, i.e. the sequence will always be C<ev_prepare>, blocking, |
2271 | C<ev_check> so if you have one watcher of each kind they will always be |
2656 | C<ev_check> so if you have one watcher of each kind they will always be |
… | |
… | |
2355 | struct pollfd fds [nfd]; |
2740 | struct pollfd fds [nfd]; |
2356 | // actual code will need to loop here and realloc etc. |
2741 | // actual code will need to loop here and realloc etc. |
2357 | adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
2742 | adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
2358 | |
2743 | |
2359 | /* the callback is illegal, but won't be called as we stop during check */ |
2744 | /* the callback is illegal, but won't be called as we stop during check */ |
2360 | ev_timer_init (&tw, 0, timeout * 1e-3); |
2745 | ev_timer_init (&tw, 0, timeout * 1e-3, 0.); |
2361 | ev_timer_start (loop, &tw); |
2746 | ev_timer_start (loop, &tw); |
2362 | |
2747 | |
2363 | // create one ev_io per pollfd |
2748 | // create one ev_io per pollfd |
2364 | for (int i = 0; i < nfd; ++i) |
2749 | for (int i = 0; i < nfd; ++i) |
2365 | { |
2750 | { |
… | |
… | |
2439 | |
2824 | |
2440 | if (timeout >= 0) |
2825 | if (timeout >= 0) |
2441 | // create/start timer |
2826 | // create/start timer |
2442 | |
2827 | |
2443 | // poll |
2828 | // poll |
2444 | ev_loop (EV_A_ 0); |
2829 | ev_run (EV_A_ 0); |
2445 | |
2830 | |
2446 | // stop timer again |
2831 | // stop timer again |
2447 | if (timeout >= 0) |
2832 | if (timeout >= 0) |
2448 | ev_timer_stop (EV_A_ &to); |
2833 | ev_timer_stop (EV_A_ &to); |
2449 | |
2834 | |
… | |
… | |
2527 | if you do not want that, you need to temporarily stop the embed watcher). |
2912 | if you do not want that, you need to temporarily stop the embed watcher). |
2528 | |
2913 | |
2529 | =item ev_embed_sweep (loop, ev_embed *) |
2914 | =item ev_embed_sweep (loop, ev_embed *) |
2530 | |
2915 | |
2531 | Make a single, non-blocking sweep over the embedded loop. This works |
2916 | Make a single, non-blocking sweep over the embedded loop. This works |
2532 | similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most |
2917 | similarly to C<ev_run (embedded_loop, EVRUN_NOWAIT)>, but in the most |
2533 | appropriate way for embedded loops. |
2918 | appropriate way for embedded loops. |
2534 | |
2919 | |
2535 | =item struct ev_loop *other [read-only] |
2920 | =item struct ev_loop *other [read-only] |
2536 | |
2921 | |
2537 | The embedded event loop. |
2922 | The embedded event loop. |
… | |
… | |
2595 | event loop blocks next and before C<ev_check> watchers are being called, |
2980 | event loop blocks next and before C<ev_check> watchers are being called, |
2596 | and only in the child after the fork. If whoever good citizen calling |
2981 | and only in the child after the fork. If whoever good citizen calling |
2597 | C<ev_default_fork> cheats and calls it in the wrong process, the fork |
2982 | C<ev_default_fork> cheats and calls it in the wrong process, the fork |
2598 | handlers will be invoked, too, of course. |
2983 | handlers will be invoked, too, of course. |
2599 | |
2984 | |
|
|
2985 | =head3 The special problem of life after fork - how is it possible? |
|
|
2986 | |
|
|
2987 | Most uses of C<fork()> consist of forking, then some simple calls to set |
|
|
2988 | up/change the process environment, followed by a call to C<exec()>. This |
|
|
2989 | sequence should be handled by libev without any problems. |
|
|
2990 | |
|
|
2991 | This changes when the application actually wants to do event handling |
|
|
2992 | in the child, or both parent in child, in effect "continuing" after the |
|
|
2993 | fork. |
|
|
2994 | |
|
|
2995 | The default mode of operation (for libev, with application help to detect |
|
|
2996 | forks) is to duplicate all the state in the child, as would be expected |
|
|
2997 | when I<either> the parent I<or> the child process continues. |
|
|
2998 | |
|
|
2999 | When both processes want to continue using libev, then this is usually the |
|
|
3000 | wrong result. In that case, usually one process (typically the parent) is |
|
|
3001 | supposed to continue with all watchers in place as before, while the other |
|
|
3002 | process typically wants to start fresh, i.e. without any active watchers. |
|
|
3003 | |
|
|
3004 | The cleanest and most efficient way to achieve that with libev is to |
|
|
3005 | simply create a new event loop, which of course will be "empty", and |
|
|
3006 | use that for new watchers. This has the advantage of not touching more |
|
|
3007 | memory than necessary, and thus avoiding the copy-on-write, and the |
|
|
3008 | disadvantage of having to use multiple event loops (which do not support |
|
|
3009 | signal watchers). |
|
|
3010 | |
|
|
3011 | When this is not possible, or you want to use the default loop for |
|
|
3012 | other reasons, then in the process that wants to start "fresh", call |
|
|
3013 | C<ev_default_destroy ()> followed by C<ev_default_loop (...)>. Destroying |
|
|
3014 | the default loop will "orphan" (not stop) all registered watchers, so you |
|
|
3015 | have to be careful not to execute code that modifies those watchers. Note |
|
|
3016 | also that in that case, you have to re-register any signal watchers. |
|
|
3017 | |
2600 | =head3 Watcher-Specific Functions and Data Members |
3018 | =head3 Watcher-Specific Functions and Data Members |
2601 | |
3019 | |
2602 | =over 4 |
3020 | =over 4 |
2603 | |
3021 | |
2604 | =item ev_fork_init (ev_signal *, callback) |
3022 | =item ev_fork_init (ev_signal *, callback) |
… | |
… | |
2608 | believe me. |
3026 | believe me. |
2609 | |
3027 | |
2610 | =back |
3028 | =back |
2611 | |
3029 | |
2612 | |
3030 | |
2613 | =head2 C<ev_async> - how to wake up another event loop |
3031 | =head2 C<ev_async> - how to wake up an event loop |
2614 | |
3032 | |
2615 | In general, you cannot use an C<ev_loop> from multiple threads or other |
3033 | In general, you cannot use an C<ev_run> from multiple threads or other |
2616 | asynchronous sources such as signal handlers (as opposed to multiple event |
3034 | asynchronous sources such as signal handlers (as opposed to multiple event |
2617 | loops - those are of course safe to use in different threads). |
3035 | loops - those are of course safe to use in different threads). |
2618 | |
3036 | |
2619 | Sometimes, however, you need to wake up another event loop you do not |
3037 | Sometimes, however, you need to wake up an event loop you do not control, |
2620 | control, for example because it belongs to another thread. This is what |
3038 | for example because it belongs to another thread. This is what C<ev_async> |
2621 | C<ev_async> watchers do: as long as the C<ev_async> watcher is active, you |
3039 | watchers do: as long as the C<ev_async> watcher is active, you can signal |
2622 | can signal it by calling C<ev_async_send>, which is thread- and signal |
3040 | it by calling C<ev_async_send>, which is thread- and signal safe. |
2623 | safe. |
|
|
2624 | |
3041 | |
2625 | This functionality is very similar to C<ev_signal> watchers, as signals, |
3042 | This functionality is very similar to C<ev_signal> watchers, as signals, |
2626 | too, are asynchronous in nature, and signals, too, will be compressed |
3043 | too, are asynchronous in nature, and signals, too, will be compressed |
2627 | (i.e. the number of callback invocations may be less than the number of |
3044 | (i.e. the number of callback invocations may be less than the number of |
2628 | C<ev_async_sent> calls). |
3045 | C<ev_async_sent> calls). |
… | |
… | |
2633 | =head3 Queueing |
3050 | =head3 Queueing |
2634 | |
3051 | |
2635 | C<ev_async> does not support queueing of data in any way. The reason |
3052 | C<ev_async> does not support queueing of data in any way. The reason |
2636 | is that the author does not know of a simple (or any) algorithm for a |
3053 | is that the author does not know of a simple (or any) algorithm for a |
2637 | multiple-writer-single-reader queue that works in all cases and doesn't |
3054 | multiple-writer-single-reader queue that works in all cases and doesn't |
2638 | need elaborate support such as pthreads. |
3055 | need elaborate support such as pthreads or unportable memory access |
|
|
3056 | semantics. |
2639 | |
3057 | |
2640 | That means that if you want to queue data, you have to provide your own |
3058 | That means that if you want to queue data, you have to provide your own |
2641 | queue. But at least I can tell you how to implement locking around your |
3059 | queue. But at least I can tell you how to implement locking around your |
2642 | queue: |
3060 | queue: |
2643 | |
3061 | |
… | |
… | |
2782 | |
3200 | |
2783 | If C<timeout> is less than 0, then no timeout watcher will be |
3201 | If C<timeout> is less than 0, then no timeout watcher will be |
2784 | started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and |
3202 | started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and |
2785 | repeat = 0) will be started. C<0> is a valid timeout. |
3203 | repeat = 0) will be started. C<0> is a valid timeout. |
2786 | |
3204 | |
2787 | The callback has the type C<void (*cb)(int revents, void *arg)> and gets |
3205 | The callback has the type C<void (*cb)(int revents, void *arg)> and is |
2788 | passed an C<revents> set like normal event callbacks (a combination of |
3206 | passed an C<revents> set like normal event callbacks (a combination of |
2789 | C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMEOUT>) and the C<arg> |
3207 | C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMER>) and the C<arg> |
2790 | value passed to C<ev_once>. Note that it is possible to receive I<both> |
3208 | value passed to C<ev_once>. Note that it is possible to receive I<both> |
2791 | a timeout and an io event at the same time - you probably should give io |
3209 | a timeout and an io event at the same time - you probably should give io |
2792 | events precedence. |
3210 | events precedence. |
2793 | |
3211 | |
2794 | Example: wait up to ten seconds for data to appear on STDIN_FILENO. |
3212 | Example: wait up to ten seconds for data to appear on STDIN_FILENO. |
2795 | |
3213 | |
2796 | static void stdin_ready (int revents, void *arg) |
3214 | static void stdin_ready (int revents, void *arg) |
2797 | { |
3215 | { |
2798 | if (revents & EV_READ) |
3216 | if (revents & EV_READ) |
2799 | /* stdin might have data for us, joy! */; |
3217 | /* stdin might have data for us, joy! */; |
2800 | else if (revents & EV_TIMEOUT) |
3218 | else if (revents & EV_TIMER) |
2801 | /* doh, nothing entered */; |
3219 | /* doh, nothing entered */; |
2802 | } |
3220 | } |
2803 | |
3221 | |
2804 | ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
3222 | ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
2805 | |
3223 | |
2806 | =item ev_feed_event (struct ev_loop *, watcher *, int revents) |
|
|
2807 | |
|
|
2808 | Feeds the given event set into the event loop, as if the specified event |
|
|
2809 | had happened for the specified watcher (which must be a pointer to an |
|
|
2810 | initialised but not necessarily started event watcher). |
|
|
2811 | |
|
|
2812 | =item ev_feed_fd_event (struct ev_loop *, int fd, int revents) |
3224 | =item ev_feed_fd_event (loop, int fd, int revents) |
2813 | |
3225 | |
2814 | Feed an event on the given fd, as if a file descriptor backend detected |
3226 | Feed an event on the given fd, as if a file descriptor backend detected |
2815 | the given events it. |
3227 | the given events it. |
2816 | |
3228 | |
2817 | =item ev_feed_signal_event (struct ev_loop *loop, int signum) |
3229 | =item ev_feed_signal_event (loop, int signum) |
2818 | |
3230 | |
2819 | Feed an event as if the given signal occurred (C<loop> must be the default |
3231 | Feed an event as if the given signal occurred (C<loop> must be the default |
2820 | loop!). |
3232 | loop!). |
2821 | |
3233 | |
2822 | =back |
3234 | =back |
… | |
… | |
2902 | |
3314 | |
2903 | =over 4 |
3315 | =over 4 |
2904 | |
3316 | |
2905 | =item ev::TYPE::TYPE () |
3317 | =item ev::TYPE::TYPE () |
2906 | |
3318 | |
2907 | =item ev::TYPE::TYPE (struct ev_loop *) |
3319 | =item ev::TYPE::TYPE (loop) |
2908 | |
3320 | |
2909 | =item ev::TYPE::~TYPE |
3321 | =item ev::TYPE::~TYPE |
2910 | |
3322 | |
2911 | The constructor (optionally) takes an event loop to associate the watcher |
3323 | The constructor (optionally) takes an event loop to associate the watcher |
2912 | with. If it is omitted, it will use C<EV_DEFAULT>. |
3324 | with. If it is omitted, it will use C<EV_DEFAULT>. |
… | |
… | |
2945 | myclass obj; |
3357 | myclass obj; |
2946 | ev::io iow; |
3358 | ev::io iow; |
2947 | iow.set <myclass, &myclass::io_cb> (&obj); |
3359 | iow.set <myclass, &myclass::io_cb> (&obj); |
2948 | |
3360 | |
2949 | =item w->set (object *) |
3361 | =item w->set (object *) |
2950 | |
|
|
2951 | This is an B<experimental> feature that might go away in a future version. |
|
|
2952 | |
3362 | |
2953 | This is a variation of a method callback - leaving out the method to call |
3363 | This is a variation of a method callback - leaving out the method to call |
2954 | will default the method to C<operator ()>, which makes it possible to use |
3364 | will default the method to C<operator ()>, which makes it possible to use |
2955 | functor objects without having to manually specify the C<operator ()> all |
3365 | functor objects without having to manually specify the C<operator ()> all |
2956 | the time. Incidentally, you can then also leave out the template argument |
3366 | the time. Incidentally, you can then also leave out the template argument |
… | |
… | |
2989 | Example: Use a plain function as callback. |
3399 | Example: Use a plain function as callback. |
2990 | |
3400 | |
2991 | static void io_cb (ev::io &w, int revents) { } |
3401 | static void io_cb (ev::io &w, int revents) { } |
2992 | iow.set <io_cb> (); |
3402 | iow.set <io_cb> (); |
2993 | |
3403 | |
2994 | =item w->set (struct ev_loop *) |
3404 | =item w->set (loop) |
2995 | |
3405 | |
2996 | Associates a different C<struct ev_loop> with this watcher. You can only |
3406 | Associates a different C<struct ev_loop> with this watcher. You can only |
2997 | do this when the watcher is inactive (and not pending either). |
3407 | do this when the watcher is inactive (and not pending either). |
2998 | |
3408 | |
2999 | =item w->set ([arguments]) |
3409 | =item w->set ([arguments]) |
3000 | |
3410 | |
3001 | Basically the same as C<ev_TYPE_set>, with the same arguments. Must be |
3411 | Basically the same as C<ev_TYPE_set>, with the same arguments. Either this |
3002 | called at least once. Unlike the C counterpart, an active watcher gets |
3412 | method or a suitable start method must be called at least once. Unlike the |
3003 | automatically stopped and restarted when reconfiguring it with this |
3413 | C counterpart, an active watcher gets automatically stopped and restarted |
3004 | method. |
3414 | when reconfiguring it with this method. |
3005 | |
3415 | |
3006 | =item w->start () |
3416 | =item w->start () |
3007 | |
3417 | |
3008 | Starts the watcher. Note that there is no C<loop> argument, as the |
3418 | Starts the watcher. Note that there is no C<loop> argument, as the |
3009 | constructor already stores the event loop. |
3419 | constructor already stores the event loop. |
3010 | |
3420 | |
|
|
3421 | =item w->start ([arguments]) |
|
|
3422 | |
|
|
3423 | Instead of calling C<set> and C<start> methods separately, it is often |
|
|
3424 | convenient to wrap them in one call. Uses the same type of arguments as |
|
|
3425 | the configure C<set> method of the watcher. |
|
|
3426 | |
3011 | =item w->stop () |
3427 | =item w->stop () |
3012 | |
3428 | |
3013 | Stops the watcher if it is active. Again, no C<loop> argument. |
3429 | Stops the watcher if it is active. Again, no C<loop> argument. |
3014 | |
3430 | |
3015 | =item w->again () (C<ev::timer>, C<ev::periodic> only) |
3431 | =item w->again () (C<ev::timer>, C<ev::periodic> only) |
… | |
… | |
3027 | |
3443 | |
3028 | =back |
3444 | =back |
3029 | |
3445 | |
3030 | =back |
3446 | =back |
3031 | |
3447 | |
3032 | Example: Define a class with an IO and idle watcher, start one of them in |
3448 | Example: Define a class with two I/O and idle watchers, start the I/O |
3033 | the constructor. |
3449 | watchers in the constructor. |
3034 | |
3450 | |
3035 | class myclass |
3451 | class myclass |
3036 | { |
3452 | { |
3037 | ev::io io ; void io_cb (ev::io &w, int revents); |
3453 | ev::io io ; void io_cb (ev::io &w, int revents); |
|
|
3454 | ev::io2 io2 ; void io2_cb (ev::io &w, int revents); |
3038 | ev::idle idle; void idle_cb (ev::idle &w, int revents); |
3455 | ev::idle idle; void idle_cb (ev::idle &w, int revents); |
3039 | |
3456 | |
3040 | myclass (int fd) |
3457 | myclass (int fd) |
3041 | { |
3458 | { |
3042 | io .set <myclass, &myclass::io_cb > (this); |
3459 | io .set <myclass, &myclass::io_cb > (this); |
|
|
3460 | io2 .set <myclass, &myclass::io2_cb > (this); |
3043 | idle.set <myclass, &myclass::idle_cb> (this); |
3461 | idle.set <myclass, &myclass::idle_cb> (this); |
3044 | |
3462 | |
3045 | io.start (fd, ev::READ); |
3463 | io.set (fd, ev::WRITE); // configure the watcher |
|
|
3464 | io.start (); // start it whenever convenient |
|
|
3465 | |
|
|
3466 | io2.start (fd, ev::READ); // set + start in one call |
3046 | } |
3467 | } |
3047 | }; |
3468 | }; |
3048 | |
3469 | |
3049 | |
3470 | |
3050 | =head1 OTHER LANGUAGE BINDINGS |
3471 | =head1 OTHER LANGUAGE BINDINGS |
… | |
… | |
3096 | =item Ocaml |
3517 | =item Ocaml |
3097 | |
3518 | |
3098 | Erkki Seppala has written Ocaml bindings for libev, to be found at |
3519 | Erkki Seppala has written Ocaml bindings for libev, to be found at |
3099 | L<http://modeemi.cs.tut.fi/~flux/software/ocaml-ev/>. |
3520 | L<http://modeemi.cs.tut.fi/~flux/software/ocaml-ev/>. |
3100 | |
3521 | |
|
|
3522 | =item Lua |
|
|
3523 | |
|
|
3524 | Brian Maher has written a partial interface to libev for lua (at the |
|
|
3525 | time of this writing, only C<ev_io> and C<ev_timer>), to be found at |
|
|
3526 | L<http://github.com/brimworks/lua-ev>. |
|
|
3527 | |
3101 | =back |
3528 | =back |
3102 | |
3529 | |
3103 | |
3530 | |
3104 | =head1 MACRO MAGIC |
3531 | =head1 MACRO MAGIC |
3105 | |
3532 | |
… | |
… | |
3118 | loop argument"). The C<EV_A> form is used when this is the sole argument, |
3545 | loop argument"). The C<EV_A> form is used when this is the sole argument, |
3119 | C<EV_A_> is used when other arguments are following. Example: |
3546 | C<EV_A_> is used when other arguments are following. Example: |
3120 | |
3547 | |
3121 | ev_unref (EV_A); |
3548 | ev_unref (EV_A); |
3122 | ev_timer_add (EV_A_ watcher); |
3549 | ev_timer_add (EV_A_ watcher); |
3123 | ev_loop (EV_A_ 0); |
3550 | ev_run (EV_A_ 0); |
3124 | |
3551 | |
3125 | It assumes the variable C<loop> of type C<struct ev_loop *> is in scope, |
3552 | It assumes the variable C<loop> of type C<struct ev_loop *> is in scope, |
3126 | which is often provided by the following macro. |
3553 | which is often provided by the following macro. |
3127 | |
3554 | |
3128 | =item C<EV_P>, C<EV_P_> |
3555 | =item C<EV_P>, C<EV_P_> |
… | |
… | |
3168 | } |
3595 | } |
3169 | |
3596 | |
3170 | ev_check check; |
3597 | ev_check check; |
3171 | ev_check_init (&check, check_cb); |
3598 | ev_check_init (&check, check_cb); |
3172 | ev_check_start (EV_DEFAULT_ &check); |
3599 | ev_check_start (EV_DEFAULT_ &check); |
3173 | ev_loop (EV_DEFAULT_ 0); |
3600 | ev_run (EV_DEFAULT_ 0); |
3174 | |
3601 | |
3175 | =head1 EMBEDDING |
3602 | =head1 EMBEDDING |
3176 | |
3603 | |
3177 | Libev can (and often is) directly embedded into host |
3604 | Libev can (and often is) directly embedded into host |
3178 | applications. Examples of applications that embed it include the Deliantra |
3605 | applications. Examples of applications that embed it include the Deliantra |
… | |
… | |
3258 | libev.m4 |
3685 | libev.m4 |
3259 | |
3686 | |
3260 | =head2 PREPROCESSOR SYMBOLS/MACROS |
3687 | =head2 PREPROCESSOR SYMBOLS/MACROS |
3261 | |
3688 | |
3262 | Libev can be configured via a variety of preprocessor symbols you have to |
3689 | Libev can be configured via a variety of preprocessor symbols you have to |
3263 | define before including any of its files. The default in the absence of |
3690 | define before including (or compiling) any of its files. The default in |
3264 | autoconf is documented for every option. |
3691 | the absence of autoconf is documented for every option. |
|
|
3692 | |
|
|
3693 | Symbols marked with "(h)" do not change the ABI, and can have different |
|
|
3694 | values when compiling libev vs. including F<ev.h>, so it is permissible |
|
|
3695 | to redefine them before including F<ev.h> without breaking compatibility |
|
|
3696 | to a compiled library. All other symbols change the ABI, which means all |
|
|
3697 | users of libev and the libev code itself must be compiled with compatible |
|
|
3698 | settings. |
3265 | |
3699 | |
3266 | =over 4 |
3700 | =over 4 |
3267 | |
3701 | |
|
|
3702 | =item EV_COMPAT3 (h) |
|
|
3703 | |
|
|
3704 | Backwards compatibility is a major concern for libev. This is why this |
|
|
3705 | release of libev comes with wrappers for the functions and symbols that |
|
|
3706 | have been renamed between libev version 3 and 4. |
|
|
3707 | |
|
|
3708 | You can disable these wrappers (to test compatibility with future |
|
|
3709 | versions) by defining C<EV_COMPAT3> to C<0> when compiling your |
|
|
3710 | sources. This has the additional advantage that you can drop the C<struct> |
|
|
3711 | from C<struct ev_loop> declarations, as libev will provide an C<ev_loop> |
|
|
3712 | typedef in that case. |
|
|
3713 | |
|
|
3714 | In some future version, the default for C<EV_COMPAT3> will become C<0>, |
|
|
3715 | and in some even more future version the compatibility code will be |
|
|
3716 | removed completely. |
|
|
3717 | |
3268 | =item EV_STANDALONE |
3718 | =item EV_STANDALONE (h) |
3269 | |
3719 | |
3270 | Must always be C<1> if you do not use autoconf configuration, which |
3720 | Must always be C<1> if you do not use autoconf configuration, which |
3271 | keeps libev from including F<config.h>, and it also defines dummy |
3721 | keeps libev from including F<config.h>, and it also defines dummy |
3272 | implementations for some libevent functions (such as logging, which is not |
3722 | implementations for some libevent functions (such as logging, which is not |
3273 | supported). It will also not define any of the structs usually found in |
3723 | supported). It will also not define any of the structs usually found in |
3274 | F<event.h> that are not directly supported by the libev core alone. |
3724 | F<event.h> that are not directly supported by the libev core alone. |
3275 | |
3725 | |
3276 | In stanbdalone mode, libev will still try to automatically deduce the |
3726 | In standalone mode, libev will still try to automatically deduce the |
3277 | configuration, but has to be more conservative. |
3727 | configuration, but has to be more conservative. |
3278 | |
3728 | |
3279 | =item EV_USE_MONOTONIC |
3729 | =item EV_USE_MONOTONIC |
3280 | |
3730 | |
3281 | If defined to be C<1>, libev will try to detect the availability of the |
3731 | If defined to be C<1>, libev will try to detect the availability of the |
… | |
… | |
3346 | be used is the winsock select). This means that it will call |
3796 | be used is the winsock select). This means that it will call |
3347 | C<_get_osfhandle> on the fd to convert it to an OS handle. Otherwise, |
3797 | C<_get_osfhandle> on the fd to convert it to an OS handle. Otherwise, |
3348 | it is assumed that all these functions actually work on fds, even |
3798 | it is assumed that all these functions actually work on fds, even |
3349 | on win32. Should not be defined on non-win32 platforms. |
3799 | on win32. Should not be defined on non-win32 platforms. |
3350 | |
3800 | |
3351 | =item EV_FD_TO_WIN32_HANDLE |
3801 | =item EV_FD_TO_WIN32_HANDLE(fd) |
3352 | |
3802 | |
3353 | If C<EV_SELECT_IS_WINSOCKET> is enabled, then libev needs a way to map |
3803 | If C<EV_SELECT_IS_WINSOCKET> is enabled, then libev needs a way to map |
3354 | file descriptors to socket handles. When not defining this symbol (the |
3804 | file descriptors to socket handles. When not defining this symbol (the |
3355 | default), then libev will call C<_get_osfhandle>, which is usually |
3805 | default), then libev will call C<_get_osfhandle>, which is usually |
3356 | correct. In some cases, programs use their own file descriptor management, |
3806 | correct. In some cases, programs use their own file descriptor management, |
3357 | in which case they can provide this function to map fds to socket handles. |
3807 | in which case they can provide this function to map fds to socket handles. |
|
|
3808 | |
|
|
3809 | =item EV_WIN32_HANDLE_TO_FD(handle) |
|
|
3810 | |
|
|
3811 | If C<EV_SELECT_IS_WINSOCKET> then libev maps handles to file descriptors |
|
|
3812 | using the standard C<_open_osfhandle> function. For programs implementing |
|
|
3813 | their own fd to handle mapping, overwriting this function makes it easier |
|
|
3814 | to do so. This can be done by defining this macro to an appropriate value. |
|
|
3815 | |
|
|
3816 | =item EV_WIN32_CLOSE_FD(fd) |
|
|
3817 | |
|
|
3818 | If programs implement their own fd to handle mapping on win32, then this |
|
|
3819 | macro can be used to override the C<close> function, useful to unregister |
|
|
3820 | file descriptors again. Note that the replacement function has to close |
|
|
3821 | the underlying OS handle. |
3358 | |
3822 | |
3359 | =item EV_USE_POLL |
3823 | =item EV_USE_POLL |
3360 | |
3824 | |
3361 | If defined to be C<1>, libev will compile in support for the C<poll>(2) |
3825 | If defined to be C<1>, libev will compile in support for the C<poll>(2) |
3362 | backend. Otherwise it will be enabled on non-win32 platforms. It |
3826 | backend. Otherwise it will be enabled on non-win32 platforms. It |
… | |
… | |
3409 | as well as for signal and thread safety in C<ev_async> watchers. |
3873 | as well as for signal and thread safety in C<ev_async> watchers. |
3410 | |
3874 | |
3411 | In the absence of this define, libev will use C<sig_atomic_t volatile> |
3875 | In the absence of this define, libev will use C<sig_atomic_t volatile> |
3412 | (from F<signal.h>), which is usually good enough on most platforms. |
3876 | (from F<signal.h>), which is usually good enough on most platforms. |
3413 | |
3877 | |
3414 | =item EV_H |
3878 | =item EV_H (h) |
3415 | |
3879 | |
3416 | The name of the F<ev.h> header file used to include it. The default if |
3880 | The name of the F<ev.h> header file used to include it. The default if |
3417 | undefined is C<"ev.h"> in F<event.h>, F<ev.c> and F<ev++.h>. This can be |
3881 | undefined is C<"ev.h"> in F<event.h>, F<ev.c> and F<ev++.h>. This can be |
3418 | used to virtually rename the F<ev.h> header file in case of conflicts. |
3882 | used to virtually rename the F<ev.h> header file in case of conflicts. |
3419 | |
3883 | |
3420 | =item EV_CONFIG_H |
3884 | =item EV_CONFIG_H (h) |
3421 | |
3885 | |
3422 | If C<EV_STANDALONE> isn't C<1>, this variable can be used to override |
3886 | If C<EV_STANDALONE> isn't C<1>, this variable can be used to override |
3423 | F<ev.c>'s idea of where to find the F<config.h> file, similarly to |
3887 | F<ev.c>'s idea of where to find the F<config.h> file, similarly to |
3424 | C<EV_H>, above. |
3888 | C<EV_H>, above. |
3425 | |
3889 | |
3426 | =item EV_EVENT_H |
3890 | =item EV_EVENT_H (h) |
3427 | |
3891 | |
3428 | Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea |
3892 | Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea |
3429 | of how the F<event.h> header can be found, the default is C<"event.h">. |
3893 | of how the F<event.h> header can be found, the default is C<"event.h">. |
3430 | |
3894 | |
3431 | =item EV_PROTOTYPES |
3895 | =item EV_PROTOTYPES (h) |
3432 | |
3896 | |
3433 | If defined to be C<0>, then F<ev.h> will not define any function |
3897 | If defined to be C<0>, then F<ev.h> will not define any function |
3434 | prototypes, but still define all the structs and other symbols. This is |
3898 | prototypes, but still define all the structs and other symbols. This is |
3435 | occasionally useful if you want to provide your own wrapper functions |
3899 | occasionally useful if you want to provide your own wrapper functions |
3436 | around libev functions. |
3900 | around libev functions. |
… | |
… | |
3458 | fine. |
3922 | fine. |
3459 | |
3923 | |
3460 | If your embedding application does not need any priorities, defining these |
3924 | If your embedding application does not need any priorities, defining these |
3461 | both to C<0> will save some memory and CPU. |
3925 | both to C<0> will save some memory and CPU. |
3462 | |
3926 | |
3463 | =item EV_PERIODIC_ENABLE |
3927 | =item EV_PERIODIC_ENABLE, EV_IDLE_ENABLE, EV_EMBED_ENABLE, EV_STAT_ENABLE, |
|
|
3928 | EV_PREPARE_ENABLE, EV_CHECK_ENABLE, EV_FORK_ENABLE, EV_SIGNAL_ENABLE, |
|
|
3929 | EV_ASYNC_ENABLE, EV_CHILD_ENABLE. |
3464 | |
3930 | |
3465 | If undefined or defined to be C<1>, then periodic timers are supported. If |
3931 | If undefined or defined to be C<1> (and the platform supports it), then |
3466 | defined to be C<0>, then they are not. Disabling them saves a few kB of |
3932 | the respective watcher type is supported. If defined to be C<0>, then it |
3467 | code. |
3933 | is not. Disabling watcher types mainly saves code size. |
3468 | |
3934 | |
3469 | =item EV_IDLE_ENABLE |
3935 | =item EV_FEATURES |
3470 | |
|
|
3471 | If undefined or defined to be C<1>, then idle watchers are supported. If |
|
|
3472 | defined to be C<0>, then they are not. Disabling them saves a few kB of |
|
|
3473 | code. |
|
|
3474 | |
|
|
3475 | =item EV_EMBED_ENABLE |
|
|
3476 | |
|
|
3477 | If undefined or defined to be C<1>, then embed watchers are supported. If |
|
|
3478 | defined to be C<0>, then they are not. Embed watchers rely on most other |
|
|
3479 | watcher types, which therefore must not be disabled. |
|
|
3480 | |
|
|
3481 | =item EV_STAT_ENABLE |
|
|
3482 | |
|
|
3483 | If undefined or defined to be C<1>, then stat watchers are supported. If |
|
|
3484 | defined to be C<0>, then they are not. |
|
|
3485 | |
|
|
3486 | =item EV_FORK_ENABLE |
|
|
3487 | |
|
|
3488 | If undefined or defined to be C<1>, then fork watchers are supported. If |
|
|
3489 | defined to be C<0>, then they are not. |
|
|
3490 | |
|
|
3491 | =item EV_ASYNC_ENABLE |
|
|
3492 | |
|
|
3493 | If undefined or defined to be C<1>, then async watchers are supported. If |
|
|
3494 | defined to be C<0>, then they are not. |
|
|
3495 | |
|
|
3496 | =item EV_MINIMAL |
|
|
3497 | |
3936 | |
3498 | If you need to shave off some kilobytes of code at the expense of some |
3937 | If you need to shave off some kilobytes of code at the expense of some |
3499 | speed, define this symbol to C<1>. Currently this is used to override some |
3938 | speed (but with the full API), you can define this symbol to request |
3500 | inlining decisions, saves roughly 30% code size on amd64. It also selects a |
3939 | certain subsets of functionality. The default is to enable all features |
3501 | much smaller 2-heap for timer management over the default 4-heap. |
3940 | that can be enabled on the platform. |
|
|
3941 | |
|
|
3942 | A typical way to use this symbol is to define it to C<0> (or to a bitset |
|
|
3943 | with some broad features you want) and then selectively re-enable |
|
|
3944 | additional parts you want, for example if you want everything minimal, |
|
|
3945 | but multiple event loop support, async and child watchers and the poll |
|
|
3946 | backend, use this: |
|
|
3947 | |
|
|
3948 | #define EV_FEATURES 0 |
|
|
3949 | #define EV_MULTIPLICITY 1 |
|
|
3950 | #define EV_USE_POLL 1 |
|
|
3951 | #define EV_CHILD_ENABLE 1 |
|
|
3952 | #define EV_ASYNC_ENABLE 1 |
|
|
3953 | |
|
|
3954 | The actual value is a bitset, it can be a combination of the following |
|
|
3955 | values: |
|
|
3956 | |
|
|
3957 | =over 4 |
|
|
3958 | |
|
|
3959 | =item C<1> - faster/larger code |
|
|
3960 | |
|
|
3961 | Use larger code to speed up some operations. |
|
|
3962 | |
|
|
3963 | Currently this is used to override some inlining decisions (enlarging the |
|
|
3964 | code size by roughly 30% on amd64). |
|
|
3965 | |
|
|
3966 | When optimising for size, use of compiler flags such as C<-Os> with |
|
|
3967 | gcc is recommended, as well as C<-DNDEBUG>, as libev contains a number of |
|
|
3968 | assertions. |
|
|
3969 | |
|
|
3970 | =item C<2> - faster/larger data structures |
|
|
3971 | |
|
|
3972 | Replaces the small 2-heap for timer management by a faster 4-heap, larger |
|
|
3973 | hash table sizes and so on. This will usually further increase code size |
|
|
3974 | and can additionally have an effect on the size of data structures at |
|
|
3975 | runtime. |
|
|
3976 | |
|
|
3977 | =item C<4> - full API configuration |
|
|
3978 | |
|
|
3979 | This enables priorities (sets C<EV_MAXPRI>=2 and C<EV_MINPRI>=-2), and |
|
|
3980 | enables multiplicity (C<EV_MULTIPLICITY>=1). |
|
|
3981 | |
|
|
3982 | =item C<8> - full API |
|
|
3983 | |
|
|
3984 | This enables a lot of the "lesser used" API functions. See C<ev.h> for |
|
|
3985 | details on which parts of the API are still available without this |
|
|
3986 | feature, and do not complain if this subset changes over time. |
|
|
3987 | |
|
|
3988 | =item C<16> - enable all optional watcher types |
|
|
3989 | |
|
|
3990 | Enables all optional watcher types. If you want to selectively enable |
|
|
3991 | only some watcher types other than I/O and timers (e.g. prepare, |
|
|
3992 | embed, async, child...) you can enable them manually by defining |
|
|
3993 | C<EV_watchertype_ENABLE> to C<1> instead. |
|
|
3994 | |
|
|
3995 | =item C<32> - enable all backends |
|
|
3996 | |
|
|
3997 | This enables all backends - without this feature, you need to enable at |
|
|
3998 | least one backend manually (C<EV_USE_SELECT> is a good choice). |
|
|
3999 | |
|
|
4000 | =item C<64> - enable OS-specific "helper" APIs |
|
|
4001 | |
|
|
4002 | Enable inotify, eventfd, signalfd and similar OS-specific helper APIs by |
|
|
4003 | default. |
|
|
4004 | |
|
|
4005 | =back |
|
|
4006 | |
|
|
4007 | Compiling with C<gcc -Os -DEV_STANDALONE -DEV_USE_EPOLL=1 -DEV_FEATURES=0> |
|
|
4008 | reduces the compiled size of libev from 24.7Kb code/2.8Kb data to 6.5Kb |
|
|
4009 | code/0.3Kb data on my GNU/Linux amd64 system, while still giving you I/O |
|
|
4010 | watchers, timers and monotonic clock support. |
|
|
4011 | |
|
|
4012 | With an intelligent-enough linker (gcc+binutils are intelligent enough |
|
|
4013 | when you use C<-Wl,--gc-sections -ffunction-sections>) functions unused by |
|
|
4014 | your program might be left out as well - a binary starting a timer and an |
|
|
4015 | I/O watcher then might come out at only 5Kb. |
|
|
4016 | |
|
|
4017 | =item EV_AVOID_STDIO |
|
|
4018 | |
|
|
4019 | If this is set to C<1> at compiletime, then libev will avoid using stdio |
|
|
4020 | functions (printf, scanf, perror etc.). This will increase the code size |
|
|
4021 | somewhat, but if your program doesn't otherwise depend on stdio and your |
|
|
4022 | libc allows it, this avoids linking in the stdio library which is quite |
|
|
4023 | big. |
|
|
4024 | |
|
|
4025 | Note that error messages might become less precise when this option is |
|
|
4026 | enabled. |
|
|
4027 | |
|
|
4028 | =item EV_NSIG |
|
|
4029 | |
|
|
4030 | The highest supported signal number, +1 (or, the number of |
|
|
4031 | signals): Normally, libev tries to deduce the maximum number of signals |
|
|
4032 | automatically, but sometimes this fails, in which case it can be |
|
|
4033 | specified. Also, using a lower number than detected (C<32> should be |
|
|
4034 | good for about any system in existence) can save some memory, as libev |
|
|
4035 | statically allocates some 12-24 bytes per signal number. |
3502 | |
4036 | |
3503 | =item EV_PID_HASHSIZE |
4037 | =item EV_PID_HASHSIZE |
3504 | |
4038 | |
3505 | C<ev_child> watchers use a small hash table to distribute workload by |
4039 | C<ev_child> watchers use a small hash table to distribute workload by |
3506 | pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more |
4040 | pid. The default size is C<16> (or C<1> with C<EV_FEATURES> disabled), |
3507 | than enough. If you need to manage thousands of children you might want to |
4041 | usually more than enough. If you need to manage thousands of children you |
3508 | increase this value (I<must> be a power of two). |
4042 | might want to increase this value (I<must> be a power of two). |
3509 | |
4043 | |
3510 | =item EV_INOTIFY_HASHSIZE |
4044 | =item EV_INOTIFY_HASHSIZE |
3511 | |
4045 | |
3512 | C<ev_stat> watchers use a small hash table to distribute workload by |
4046 | C<ev_stat> watchers use a small hash table to distribute workload by |
3513 | inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>), |
4047 | inotify watch id. The default size is C<16> (or C<1> with C<EV_FEATURES> |
3514 | usually more than enough. If you need to manage thousands of C<ev_stat> |
4048 | disabled), usually more than enough. If you need to manage thousands of |
3515 | watchers you might want to increase this value (I<must> be a power of |
4049 | C<ev_stat> watchers you might want to increase this value (I<must> be a |
3516 | two). |
4050 | power of two). |
3517 | |
4051 | |
3518 | =item EV_USE_4HEAP |
4052 | =item EV_USE_4HEAP |
3519 | |
4053 | |
3520 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
4054 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
3521 | timer and periodics heaps, libev uses a 4-heap when this symbol is defined |
4055 | timer and periodics heaps, libev uses a 4-heap when this symbol is defined |
3522 | to C<1>. The 4-heap uses more complicated (longer) code but has noticeably |
4056 | to C<1>. The 4-heap uses more complicated (longer) code but has noticeably |
3523 | faster performance with many (thousands) of watchers. |
4057 | faster performance with many (thousands) of watchers. |
3524 | |
4058 | |
3525 | The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0> |
4059 | The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it |
3526 | (disabled). |
4060 | will be C<0>. |
3527 | |
4061 | |
3528 | =item EV_HEAP_CACHE_AT |
4062 | =item EV_HEAP_CACHE_AT |
3529 | |
4063 | |
3530 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
4064 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
3531 | timer and periodics heaps, libev can cache the timestamp (I<at>) within |
4065 | timer and periodics heaps, libev can cache the timestamp (I<at>) within |
3532 | the heap structure (selected by defining C<EV_HEAP_CACHE_AT> to C<1>), |
4066 | the heap structure (selected by defining C<EV_HEAP_CACHE_AT> to C<1>), |
3533 | which uses 8-12 bytes more per watcher and a few hundred bytes more code, |
4067 | which uses 8-12 bytes more per watcher and a few hundred bytes more code, |
3534 | but avoids random read accesses on heap changes. This improves performance |
4068 | but avoids random read accesses on heap changes. This improves performance |
3535 | noticeably with many (hundreds) of watchers. |
4069 | noticeably with many (hundreds) of watchers. |
3536 | |
4070 | |
3537 | The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0> |
4071 | The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it |
3538 | (disabled). |
4072 | will be C<0>. |
3539 | |
4073 | |
3540 | =item EV_VERIFY |
4074 | =item EV_VERIFY |
3541 | |
4075 | |
3542 | Controls how much internal verification (see C<ev_loop_verify ()>) will |
4076 | Controls how much internal verification (see C<ev_verify ()>) will |
3543 | be done: If set to C<0>, no internal verification code will be compiled |
4077 | be done: If set to C<0>, no internal verification code will be compiled |
3544 | in. If set to C<1>, then verification code will be compiled in, but not |
4078 | in. If set to C<1>, then verification code will be compiled in, but not |
3545 | called. If set to C<2>, then the internal verification code will be |
4079 | called. If set to C<2>, then the internal verification code will be |
3546 | called once per loop, which can slow down libev. If set to C<3>, then the |
4080 | called once per loop, which can slow down libev. If set to C<3>, then the |
3547 | verification code will be called very frequently, which will slow down |
4081 | verification code will be called very frequently, which will slow down |
3548 | libev considerably. |
4082 | libev considerably. |
3549 | |
4083 | |
3550 | The default is C<1>, unless C<EV_MINIMAL> is set, in which case it will be |
4084 | The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it |
3551 | C<0>. |
4085 | will be C<0>. |
3552 | |
4086 | |
3553 | =item EV_COMMON |
4087 | =item EV_COMMON |
3554 | |
4088 | |
3555 | By default, all watchers have a C<void *data> member. By redefining |
4089 | By default, all watchers have a C<void *data> member. By redefining |
3556 | this macro to a something else you can include more and other types of |
4090 | this macro to something else you can include more and other types of |
3557 | members. You have to define it each time you include one of the files, |
4091 | members. You have to define it each time you include one of the files, |
3558 | though, and it must be identical each time. |
4092 | though, and it must be identical each time. |
3559 | |
4093 | |
3560 | For example, the perl EV module uses something like this: |
4094 | For example, the perl EV module uses something like this: |
3561 | |
4095 | |
… | |
… | |
3614 | file. |
4148 | file. |
3615 | |
4149 | |
3616 | The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file |
4150 | The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file |
3617 | that everybody includes and which overrides some configure choices: |
4151 | that everybody includes and which overrides some configure choices: |
3618 | |
4152 | |
3619 | #define EV_MINIMAL 1 |
4153 | #define EV_FEATURES 8 |
3620 | #define EV_USE_POLL 0 |
4154 | #define EV_USE_SELECT 1 |
3621 | #define EV_MULTIPLICITY 0 |
|
|
3622 | #define EV_PERIODIC_ENABLE 0 |
4155 | #define EV_PREPARE_ENABLE 1 |
|
|
4156 | #define EV_IDLE_ENABLE 1 |
3623 | #define EV_STAT_ENABLE 0 |
4157 | #define EV_SIGNAL_ENABLE 1 |
3624 | #define EV_FORK_ENABLE 0 |
4158 | #define EV_CHILD_ENABLE 1 |
|
|
4159 | #define EV_USE_STDEXCEPT 0 |
3625 | #define EV_CONFIG_H <config.h> |
4160 | #define EV_CONFIG_H <config.h> |
3626 | #define EV_MINPRI 0 |
|
|
3627 | #define EV_MAXPRI 0 |
|
|
3628 | |
4161 | |
3629 | #include "ev++.h" |
4162 | #include "ev++.h" |
3630 | |
4163 | |
3631 | And a F<ev_cpp.C> implementation file that contains libev proper and is compiled: |
4164 | And a F<ev_cpp.C> implementation file that contains libev proper and is compiled: |
3632 | |
4165 | |
… | |
… | |
3692 | default loop and triggering an C<ev_async> watcher from the default loop |
4225 | default loop and triggering an C<ev_async> watcher from the default loop |
3693 | watcher callback into the event loop interested in the signal. |
4226 | watcher callback into the event loop interested in the signal. |
3694 | |
4227 | |
3695 | =back |
4228 | =back |
3696 | |
4229 | |
|
|
4230 | =head4 THREAD LOCKING EXAMPLE |
|
|
4231 | |
|
|
4232 | Here is a fictitious example of how to run an event loop in a different |
|
|
4233 | thread than where callbacks are being invoked and watchers are |
|
|
4234 | created/added/removed. |
|
|
4235 | |
|
|
4236 | For a real-world example, see the C<EV::Loop::Async> perl module, |
|
|
4237 | which uses exactly this technique (which is suited for many high-level |
|
|
4238 | languages). |
|
|
4239 | |
|
|
4240 | The example uses a pthread mutex to protect the loop data, a condition |
|
|
4241 | variable to wait for callback invocations, an async watcher to notify the |
|
|
4242 | event loop thread and an unspecified mechanism to wake up the main thread. |
|
|
4243 | |
|
|
4244 | First, you need to associate some data with the event loop: |
|
|
4245 | |
|
|
4246 | typedef struct { |
|
|
4247 | mutex_t lock; /* global loop lock */ |
|
|
4248 | ev_async async_w; |
|
|
4249 | thread_t tid; |
|
|
4250 | cond_t invoke_cv; |
|
|
4251 | } userdata; |
|
|
4252 | |
|
|
4253 | void prepare_loop (EV_P) |
|
|
4254 | { |
|
|
4255 | // for simplicity, we use a static userdata struct. |
|
|
4256 | static userdata u; |
|
|
4257 | |
|
|
4258 | ev_async_init (&u->async_w, async_cb); |
|
|
4259 | ev_async_start (EV_A_ &u->async_w); |
|
|
4260 | |
|
|
4261 | pthread_mutex_init (&u->lock, 0); |
|
|
4262 | pthread_cond_init (&u->invoke_cv, 0); |
|
|
4263 | |
|
|
4264 | // now associate this with the loop |
|
|
4265 | ev_set_userdata (EV_A_ u); |
|
|
4266 | ev_set_invoke_pending_cb (EV_A_ l_invoke); |
|
|
4267 | ev_set_loop_release_cb (EV_A_ l_release, l_acquire); |
|
|
4268 | |
|
|
4269 | // then create the thread running ev_loop |
|
|
4270 | pthread_create (&u->tid, 0, l_run, EV_A); |
|
|
4271 | } |
|
|
4272 | |
|
|
4273 | The callback for the C<ev_async> watcher does nothing: the watcher is used |
|
|
4274 | solely to wake up the event loop so it takes notice of any new watchers |
|
|
4275 | that might have been added: |
|
|
4276 | |
|
|
4277 | static void |
|
|
4278 | async_cb (EV_P_ ev_async *w, int revents) |
|
|
4279 | { |
|
|
4280 | // just used for the side effects |
|
|
4281 | } |
|
|
4282 | |
|
|
4283 | The C<l_release> and C<l_acquire> callbacks simply unlock/lock the mutex |
|
|
4284 | protecting the loop data, respectively. |
|
|
4285 | |
|
|
4286 | static void |
|
|
4287 | l_release (EV_P) |
|
|
4288 | { |
|
|
4289 | userdata *u = ev_userdata (EV_A); |
|
|
4290 | pthread_mutex_unlock (&u->lock); |
|
|
4291 | } |
|
|
4292 | |
|
|
4293 | static void |
|
|
4294 | l_acquire (EV_P) |
|
|
4295 | { |
|
|
4296 | userdata *u = ev_userdata (EV_A); |
|
|
4297 | pthread_mutex_lock (&u->lock); |
|
|
4298 | } |
|
|
4299 | |
|
|
4300 | The event loop thread first acquires the mutex, and then jumps straight |
|
|
4301 | into C<ev_run>: |
|
|
4302 | |
|
|
4303 | void * |
|
|
4304 | l_run (void *thr_arg) |
|
|
4305 | { |
|
|
4306 | struct ev_loop *loop = (struct ev_loop *)thr_arg; |
|
|
4307 | |
|
|
4308 | l_acquire (EV_A); |
|
|
4309 | pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0); |
|
|
4310 | ev_run (EV_A_ 0); |
|
|
4311 | l_release (EV_A); |
|
|
4312 | |
|
|
4313 | return 0; |
|
|
4314 | } |
|
|
4315 | |
|
|
4316 | Instead of invoking all pending watchers, the C<l_invoke> callback will |
|
|
4317 | signal the main thread via some unspecified mechanism (signals? pipe |
|
|
4318 | writes? C<Async::Interrupt>?) and then waits until all pending watchers |
|
|
4319 | have been called (in a while loop because a) spurious wakeups are possible |
|
|
4320 | and b) skipping inter-thread-communication when there are no pending |
|
|
4321 | watchers is very beneficial): |
|
|
4322 | |
|
|
4323 | static void |
|
|
4324 | l_invoke (EV_P) |
|
|
4325 | { |
|
|
4326 | userdata *u = ev_userdata (EV_A); |
|
|
4327 | |
|
|
4328 | while (ev_pending_count (EV_A)) |
|
|
4329 | { |
|
|
4330 | wake_up_other_thread_in_some_magic_or_not_so_magic_way (); |
|
|
4331 | pthread_cond_wait (&u->invoke_cv, &u->lock); |
|
|
4332 | } |
|
|
4333 | } |
|
|
4334 | |
|
|
4335 | Now, whenever the main thread gets told to invoke pending watchers, it |
|
|
4336 | will grab the lock, call C<ev_invoke_pending> and then signal the loop |
|
|
4337 | thread to continue: |
|
|
4338 | |
|
|
4339 | static void |
|
|
4340 | real_invoke_pending (EV_P) |
|
|
4341 | { |
|
|
4342 | userdata *u = ev_userdata (EV_A); |
|
|
4343 | |
|
|
4344 | pthread_mutex_lock (&u->lock); |
|
|
4345 | ev_invoke_pending (EV_A); |
|
|
4346 | pthread_cond_signal (&u->invoke_cv); |
|
|
4347 | pthread_mutex_unlock (&u->lock); |
|
|
4348 | } |
|
|
4349 | |
|
|
4350 | Whenever you want to start/stop a watcher or do other modifications to an |
|
|
4351 | event loop, you will now have to lock: |
|
|
4352 | |
|
|
4353 | ev_timer timeout_watcher; |
|
|
4354 | userdata *u = ev_userdata (EV_A); |
|
|
4355 | |
|
|
4356 | ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.); |
|
|
4357 | |
|
|
4358 | pthread_mutex_lock (&u->lock); |
|
|
4359 | ev_timer_start (EV_A_ &timeout_watcher); |
|
|
4360 | ev_async_send (EV_A_ &u->async_w); |
|
|
4361 | pthread_mutex_unlock (&u->lock); |
|
|
4362 | |
|
|
4363 | Note that sending the C<ev_async> watcher is required because otherwise |
|
|
4364 | an event loop currently blocking in the kernel will have no knowledge |
|
|
4365 | about the newly added timer. By waking up the loop it will pick up any new |
|
|
4366 | watchers in the next event loop iteration. |
|
|
4367 | |
3697 | =head3 COROUTINES |
4368 | =head3 COROUTINES |
3698 | |
4369 | |
3699 | Libev is very accommodating to coroutines ("cooperative threads"): |
4370 | Libev is very accommodating to coroutines ("cooperative threads"): |
3700 | libev fully supports nesting calls to its functions from different |
4371 | libev fully supports nesting calls to its functions from different |
3701 | coroutines (e.g. you can call C<ev_loop> on the same loop from two |
4372 | coroutines (e.g. you can call C<ev_run> on the same loop from two |
3702 | different coroutines, and switch freely between both coroutines running the |
4373 | different coroutines, and switch freely between both coroutines running |
3703 | loop, as long as you don't confuse yourself). The only exception is that |
4374 | the loop, as long as you don't confuse yourself). The only exception is |
3704 | you must not do this from C<ev_periodic> reschedule callbacks. |
4375 | that you must not do this from C<ev_periodic> reschedule callbacks. |
3705 | |
4376 | |
3706 | Care has been taken to ensure that libev does not keep local state inside |
4377 | Care has been taken to ensure that libev does not keep local state inside |
3707 | C<ev_loop>, and other calls do not usually allow for coroutine switches as |
4378 | C<ev_run>, and other calls do not usually allow for coroutine switches as |
3708 | they do not call any callbacks. |
4379 | they do not call any callbacks. |
3709 | |
4380 | |
3710 | =head2 COMPILER WARNINGS |
4381 | =head2 COMPILER WARNINGS |
3711 | |
4382 | |
3712 | Depending on your compiler and compiler settings, you might get no or a |
4383 | Depending on your compiler and compiler settings, you might get no or a |
… | |
… | |
3723 | maintainable. |
4394 | maintainable. |
3724 | |
4395 | |
3725 | And of course, some compiler warnings are just plain stupid, or simply |
4396 | And of course, some compiler warnings are just plain stupid, or simply |
3726 | wrong (because they don't actually warn about the condition their message |
4397 | wrong (because they don't actually warn about the condition their message |
3727 | seems to warn about). For example, certain older gcc versions had some |
4398 | seems to warn about). For example, certain older gcc versions had some |
3728 | warnings that resulted an extreme number of false positives. These have |
4399 | warnings that resulted in an extreme number of false positives. These have |
3729 | been fixed, but some people still insist on making code warn-free with |
4400 | been fixed, but some people still insist on making code warn-free with |
3730 | such buggy versions. |
4401 | such buggy versions. |
3731 | |
4402 | |
3732 | While libev is written to generate as few warnings as possible, |
4403 | While libev is written to generate as few warnings as possible, |
3733 | "warn-free" code is not a goal, and it is recommended not to build libev |
4404 | "warn-free" code is not a goal, and it is recommended not to build libev |
… | |
… | |
3769 | I suggest using suppression lists. |
4440 | I suggest using suppression lists. |
3770 | |
4441 | |
3771 | |
4442 | |
3772 | =head1 PORTABILITY NOTES |
4443 | =head1 PORTABILITY NOTES |
3773 | |
4444 | |
|
|
4445 | =head2 GNU/LINUX 32 BIT LIMITATIONS |
|
|
4446 | |
|
|
4447 | GNU/Linux is the only common platform that supports 64 bit file/large file |
|
|
4448 | interfaces but I<disables> them by default. |
|
|
4449 | |
|
|
4450 | That means that libev compiled in the default environment doesn't support |
|
|
4451 | files larger than 2GiB or so, which mainly affects C<ev_stat> watchers. |
|
|
4452 | |
|
|
4453 | Unfortunately, many programs try to work around this GNU/Linux issue |
|
|
4454 | by enabling the large file API, which makes them incompatible with the |
|
|
4455 | standard libev compiled for their system. |
|
|
4456 | |
|
|
4457 | Likewise, libev cannot enable the large file API itself as this would |
|
|
4458 | suddenly make it incompatible to the default compile time environment, |
|
|
4459 | i.e. all programs not using special compile switches. |
|
|
4460 | |
|
|
4461 | =head2 OS/X AND DARWIN BUGS |
|
|
4462 | |
|
|
4463 | The whole thing is a bug if you ask me - basically any system interface |
|
|
4464 | you touch is broken, whether it is locales, poll, kqueue or even the |
|
|
4465 | OpenGL drivers. |
|
|
4466 | |
|
|
4467 | =head3 C<kqueue> is buggy |
|
|
4468 | |
|
|
4469 | The kqueue syscall is broken in all known versions - most versions support |
|
|
4470 | only sockets, many support pipes. |
|
|
4471 | |
|
|
4472 | Libev tries to work around this by not using C<kqueue> by default on |
|
|
4473 | this rotten platform, but of course you can still ask for it when creating |
|
|
4474 | a loop. |
|
|
4475 | |
|
|
4476 | =head3 C<poll> is buggy |
|
|
4477 | |
|
|
4478 | Instead of fixing C<kqueue>, Apple replaced their (working) C<poll> |
|
|
4479 | implementation by something calling C<kqueue> internally around the 10.5.6 |
|
|
4480 | release, so now C<kqueue> I<and> C<poll> are broken. |
|
|
4481 | |
|
|
4482 | Libev tries to work around this by not using C<poll> by default on |
|
|
4483 | this rotten platform, but of course you can still ask for it when creating |
|
|
4484 | a loop. |
|
|
4485 | |
|
|
4486 | =head3 C<select> is buggy |
|
|
4487 | |
|
|
4488 | All that's left is C<select>, and of course Apple found a way to fuck this |
|
|
4489 | one up as well: On OS/X, C<select> actively limits the number of file |
|
|
4490 | descriptors you can pass in to 1024 - your program suddenly crashes when |
|
|
4491 | you use more. |
|
|
4492 | |
|
|
4493 | There is an undocumented "workaround" for this - defining |
|
|
4494 | C<_DARWIN_UNLIMITED_SELECT>, which libev tries to use, so select I<should> |
|
|
4495 | work on OS/X. |
|
|
4496 | |
|
|
4497 | =head2 SOLARIS PROBLEMS AND WORKAROUNDS |
|
|
4498 | |
|
|
4499 | =head3 C<errno> reentrancy |
|
|
4500 | |
|
|
4501 | The default compile environment on Solaris is unfortunately so |
|
|
4502 | thread-unsafe that you can't even use components/libraries compiled |
|
|
4503 | without C<-D_REENTRANT> (as long as they use C<errno>), which, of course, |
|
|
4504 | isn't defined by default. |
|
|
4505 | |
|
|
4506 | If you want to use libev in threaded environments you have to make sure |
|
|
4507 | it's compiled with C<_REENTRANT> defined. |
|
|
4508 | |
|
|
4509 | =head3 Event port backend |
|
|
4510 | |
|
|
4511 | The scalable event interface for Solaris is called "event ports". Unfortunately, |
|
|
4512 | this mechanism is very buggy. If you run into high CPU usage, your program |
|
|
4513 | freezes or you get a large number of spurious wakeups, make sure you have |
|
|
4514 | all the relevant and latest kernel patches applied. No, I don't know which |
|
|
4515 | ones, but there are multiple ones. |
|
|
4516 | |
|
|
4517 | If you can't get it to work, you can try running the program by setting |
|
|
4518 | the environment variable C<LIBEV_FLAGS=3> to only allow C<poll> and |
|
|
4519 | C<select> backends. |
|
|
4520 | |
|
|
4521 | =head2 AIX POLL BUG |
|
|
4522 | |
|
|
4523 | AIX unfortunately has a broken C<poll.h> header. Libev works around |
|
|
4524 | this by trying to avoid the poll backend altogether (i.e. it's not even |
|
|
4525 | compiled in), which normally isn't a big problem as C<select> works fine |
|
|
4526 | with large bitsets, and AIX is dead anyway. |
|
|
4527 | |
3774 | =head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS |
4528 | =head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS |
|
|
4529 | |
|
|
4530 | =head3 General issues |
3775 | |
4531 | |
3776 | Win32 doesn't support any of the standards (e.g. POSIX) that libev |
4532 | Win32 doesn't support any of the standards (e.g. POSIX) that libev |
3777 | requires, and its I/O model is fundamentally incompatible with the POSIX |
4533 | requires, and its I/O model is fundamentally incompatible with the POSIX |
3778 | model. Libev still offers limited functionality on this platform in |
4534 | model. Libev still offers limited functionality on this platform in |
3779 | the form of the C<EVBACKEND_SELECT> backend, and only supports socket |
4535 | the form of the C<EVBACKEND_SELECT> backend, and only supports socket |
3780 | descriptors. This only applies when using Win32 natively, not when using |
4536 | descriptors. This only applies when using Win32 natively, not when using |
3781 | e.g. cygwin. |
4537 | e.g. cygwin. Actually, it only applies to the microsofts own compilers, |
|
|
4538 | as every compielr comes with a slightly differently broken/incompatible |
|
|
4539 | environment. |
3782 | |
4540 | |
3783 | Lifting these limitations would basically require the full |
4541 | Lifting these limitations would basically require the full |
3784 | re-implementation of the I/O system. If you are into these kinds of |
4542 | re-implementation of the I/O system. If you are into this kind of thing, |
3785 | things, then note that glib does exactly that for you in a very portable |
4543 | then note that glib does exactly that for you in a very portable way (note |
3786 | way (note also that glib is the slowest event library known to man). |
4544 | also that glib is the slowest event library known to man). |
3787 | |
4545 | |
3788 | There is no supported compilation method available on windows except |
4546 | There is no supported compilation method available on windows except |
3789 | embedding it into other applications. |
4547 | embedding it into other applications. |
|
|
4548 | |
|
|
4549 | Sensible signal handling is officially unsupported by Microsoft - libev |
|
|
4550 | tries its best, but under most conditions, signals will simply not work. |
3790 | |
4551 | |
3791 | Not a libev limitation but worth mentioning: windows apparently doesn't |
4552 | Not a libev limitation but worth mentioning: windows apparently doesn't |
3792 | accept large writes: instead of resulting in a partial write, windows will |
4553 | accept large writes: instead of resulting in a partial write, windows will |
3793 | either accept everything or return C<ENOBUFS> if the buffer is too large, |
4554 | either accept everything or return C<ENOBUFS> if the buffer is too large, |
3794 | so make sure you only write small amounts into your sockets (less than a |
4555 | so make sure you only write small amounts into your sockets (less than a |
… | |
… | |
3799 | the abysmal performance of winsockets, using a large number of sockets |
4560 | the abysmal performance of winsockets, using a large number of sockets |
3800 | is not recommended (and not reasonable). If your program needs to use |
4561 | is not recommended (and not reasonable). If your program needs to use |
3801 | more than a hundred or so sockets, then likely it needs to use a totally |
4562 | more than a hundred or so sockets, then likely it needs to use a totally |
3802 | different implementation for windows, as libev offers the POSIX readiness |
4563 | different implementation for windows, as libev offers the POSIX readiness |
3803 | notification model, which cannot be implemented efficiently on windows |
4564 | notification model, which cannot be implemented efficiently on windows |
3804 | (Microsoft monopoly games). |
4565 | (due to Microsoft monopoly games). |
3805 | |
4566 | |
3806 | A typical way to use libev under windows is to embed it (see the embedding |
4567 | A typical way to use libev under windows is to embed it (see the embedding |
3807 | section for details) and use the following F<evwrap.h> header file instead |
4568 | section for details) and use the following F<evwrap.h> header file instead |
3808 | of F<ev.h>: |
4569 | of F<ev.h>: |
3809 | |
4570 | |
… | |
… | |
3816 | you do I<not> compile the F<ev.c> or any other embedded source files!): |
4577 | you do I<not> compile the F<ev.c> or any other embedded source files!): |
3817 | |
4578 | |
3818 | #include "evwrap.h" |
4579 | #include "evwrap.h" |
3819 | #include "ev.c" |
4580 | #include "ev.c" |
3820 | |
4581 | |
3821 | =over 4 |
|
|
3822 | |
|
|
3823 | =item The winsocket select function |
4582 | =head3 The winsocket C<select> function |
3824 | |
4583 | |
3825 | The winsocket C<select> function doesn't follow POSIX in that it |
4584 | The winsocket C<select> function doesn't follow POSIX in that it |
3826 | requires socket I<handles> and not socket I<file descriptors> (it is |
4585 | requires socket I<handles> and not socket I<file descriptors> (it is |
3827 | also extremely buggy). This makes select very inefficient, and also |
4586 | also extremely buggy). This makes select very inefficient, and also |
3828 | requires a mapping from file descriptors to socket handles (the Microsoft |
4587 | requires a mapping from file descriptors to socket handles (the Microsoft |
… | |
… | |
3837 | #define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */ |
4596 | #define EV_SELECT_IS_WINSOCKET 1 /* forces EV_SELECT_USE_FD_SET, too */ |
3838 | |
4597 | |
3839 | Note that winsockets handling of fd sets is O(n), so you can easily get a |
4598 | Note that winsockets handling of fd sets is O(n), so you can easily get a |
3840 | complexity in the O(n²) range when using win32. |
4599 | complexity in the O(n²) range when using win32. |
3841 | |
4600 | |
3842 | =item Limited number of file descriptors |
4601 | =head3 Limited number of file descriptors |
3843 | |
4602 | |
3844 | Windows has numerous arbitrary (and low) limits on things. |
4603 | Windows has numerous arbitrary (and low) limits on things. |
3845 | |
4604 | |
3846 | Early versions of winsocket's select only supported waiting for a maximum |
4605 | Early versions of winsocket's select only supported waiting for a maximum |
3847 | of C<64> handles (probably owning to the fact that all windows kernels |
4606 | of C<64> handles (probably owning to the fact that all windows kernels |
3848 | can only wait for C<64> things at the same time internally; Microsoft |
4607 | can only wait for C<64> things at the same time internally; Microsoft |
3849 | recommends spawning a chain of threads and wait for 63 handles and the |
4608 | recommends spawning a chain of threads and wait for 63 handles and the |
3850 | previous thread in each. Great). |
4609 | previous thread in each. Sounds great!). |
3851 | |
4610 | |
3852 | Newer versions support more handles, but you need to define C<FD_SETSIZE> |
4611 | Newer versions support more handles, but you need to define C<FD_SETSIZE> |
3853 | to some high number (e.g. C<2048>) before compiling the winsocket select |
4612 | to some high number (e.g. C<2048>) before compiling the winsocket select |
3854 | call (which might be in libev or elsewhere, for example, perl does its own |
4613 | call (which might be in libev or elsewhere, for example, perl and many |
3855 | select emulation on windows). |
4614 | other interpreters do their own select emulation on windows). |
3856 | |
4615 | |
3857 | Another limit is the number of file descriptors in the Microsoft runtime |
4616 | Another limit is the number of file descriptors in the Microsoft runtime |
3858 | libraries, which by default is C<64> (there must be a hidden I<64> fetish |
4617 | libraries, which by default is C<64> (there must be a hidden I<64> |
3859 | or something like this inside Microsoft). You can increase this by calling |
4618 | fetish or something like this inside Microsoft). You can increase this |
3860 | C<_setmaxstdio>, which can increase this limit to C<2048> (another |
4619 | by calling C<_setmaxstdio>, which can increase this limit to C<2048> |
3861 | arbitrary limit), but is broken in many versions of the Microsoft runtime |
4620 | (another arbitrary limit), but is broken in many versions of the Microsoft |
3862 | libraries. |
|
|
3863 | |
|
|
3864 | This might get you to about C<512> or C<2048> sockets (depending on |
4621 | runtime libraries. This might get you to about C<512> or C<2048> sockets |
3865 | windows version and/or the phase of the moon). To get more, you need to |
4622 | (depending on windows version and/or the phase of the moon). To get more, |
3866 | wrap all I/O functions and provide your own fd management, but the cost of |
4623 | you need to wrap all I/O functions and provide your own fd management, but |
3867 | calling select (O(n²)) will likely make this unworkable. |
4624 | the cost of calling select (O(n²)) will likely make this unworkable. |
3868 | |
|
|
3869 | =back |
|
|
3870 | |
4625 | |
3871 | =head2 PORTABILITY REQUIREMENTS |
4626 | =head2 PORTABILITY REQUIREMENTS |
3872 | |
4627 | |
3873 | In addition to a working ISO-C implementation and of course the |
4628 | In addition to a working ISO-C implementation and of course the |
3874 | backend-specific APIs, libev relies on a few additional extensions: |
4629 | backend-specific APIs, libev relies on a few additional extensions: |
… | |
… | |
3913 | watchers. |
4668 | watchers. |
3914 | |
4669 | |
3915 | =item C<double> must hold a time value in seconds with enough accuracy |
4670 | =item C<double> must hold a time value in seconds with enough accuracy |
3916 | |
4671 | |
3917 | The type C<double> is used to represent timestamps. It is required to |
4672 | The type C<double> is used to represent timestamps. It is required to |
3918 | have at least 51 bits of mantissa (and 9 bits of exponent), which is good |
4673 | have at least 51 bits of mantissa (and 9 bits of exponent), which is |
3919 | enough for at least into the year 4000. This requirement is fulfilled by |
4674 | good enough for at least into the year 4000 with millisecond accuracy |
|
|
4675 | (the design goal for libev). This requirement is overfulfilled by |
3920 | implementations implementing IEEE 754 (basically all existing ones). |
4676 | implementations using IEEE 754, which is basically all existing ones. With |
|
|
4677 | IEEE 754 doubles, you get microsecond accuracy until at least 2200. |
3921 | |
4678 | |
3922 | =back |
4679 | =back |
3923 | |
4680 | |
3924 | If you know of other additional requirements drop me a note. |
4681 | If you know of other additional requirements drop me a note. |
3925 | |
4682 | |
… | |
… | |
3993 | involves iterating over all running async watchers or all signal numbers. |
4750 | involves iterating over all running async watchers or all signal numbers. |
3994 | |
4751 | |
3995 | =back |
4752 | =back |
3996 | |
4753 | |
3997 | |
4754 | |
|
|
4755 | =head1 PORTING FROM LIBEV 3.X TO 4.X |
|
|
4756 | |
|
|
4757 | The major version 4 introduced some minor incompatible changes to the API. |
|
|
4758 | |
|
|
4759 | At the moment, the C<ev.h> header file tries to implement superficial |
|
|
4760 | compatibility, so most programs should still compile. Those might be |
|
|
4761 | removed in later versions of libev, so better update early than late. |
|
|
4762 | |
|
|
4763 | =over 4 |
|
|
4764 | |
|
|
4765 | =item function/symbol renames |
|
|
4766 | |
|
|
4767 | A number of functions and symbols have been renamed: |
|
|
4768 | |
|
|
4769 | ev_loop => ev_run |
|
|
4770 | EVLOOP_NONBLOCK => EVRUN_NOWAIT |
|
|
4771 | EVLOOP_ONESHOT => EVRUN_ONCE |
|
|
4772 | |
|
|
4773 | ev_unloop => ev_break |
|
|
4774 | EVUNLOOP_CANCEL => EVBREAK_CANCEL |
|
|
4775 | EVUNLOOP_ONE => EVBREAK_ONE |
|
|
4776 | EVUNLOOP_ALL => EVBREAK_ALL |
|
|
4777 | |
|
|
4778 | EV_TIMEOUT => EV_TIMER |
|
|
4779 | |
|
|
4780 | ev_loop_count => ev_iteration |
|
|
4781 | ev_loop_depth => ev_depth |
|
|
4782 | ev_loop_verify => ev_verify |
|
|
4783 | |
|
|
4784 | Most functions working on C<struct ev_loop> objects don't have an |
|
|
4785 | C<ev_loop_> prefix, so it was removed; C<ev_loop>, C<ev_unloop> and |
|
|
4786 | associated constants have been renamed to not collide with the C<struct |
|
|
4787 | ev_loop> anymore and C<EV_TIMER> now follows the same naming scheme |
|
|
4788 | as all other watcher types. Note that C<ev_loop_fork> is still called |
|
|
4789 | C<ev_loop_fork> because it would otherwise clash with the C<ev_fork> |
|
|
4790 | typedef. |
|
|
4791 | |
|
|
4792 | =item C<EV_COMPAT3> backwards compatibility mechanism |
|
|
4793 | |
|
|
4794 | The backward compatibility mechanism can be controlled by |
|
|
4795 | C<EV_COMPAT3>. See L<PREPROCESSOR SYMBOLS/MACROS> in the L<EMBEDDING> |
|
|
4796 | section. |
|
|
4797 | |
|
|
4798 | =item C<EV_MINIMAL> mechanism replaced by C<EV_FEATURES> |
|
|
4799 | |
|
|
4800 | The preprocessor symbol C<EV_MINIMAL> has been replaced by a different |
|
|
4801 | mechanism, C<EV_FEATURES>. Programs using C<EV_MINIMAL> usually compile |
|
|
4802 | and work, but the library code will of course be larger. |
|
|
4803 | |
|
|
4804 | =back |
|
|
4805 | |
|
|
4806 | |
|
|
4807 | =head1 GLOSSARY |
|
|
4808 | |
|
|
4809 | =over 4 |
|
|
4810 | |
|
|
4811 | =item active |
|
|
4812 | |
|
|
4813 | A watcher is active as long as it has been started (has been attached to |
|
|
4814 | an event loop) but not yet stopped (disassociated from the event loop). |
|
|
4815 | |
|
|
4816 | =item application |
|
|
4817 | |
|
|
4818 | In this document, an application is whatever is using libev. |
|
|
4819 | |
|
|
4820 | =item callback |
|
|
4821 | |
|
|
4822 | The address of a function that is called when some event has been |
|
|
4823 | detected. Callbacks are being passed the event loop, the watcher that |
|
|
4824 | received the event, and the actual event bitset. |
|
|
4825 | |
|
|
4826 | =item callback invocation |
|
|
4827 | |
|
|
4828 | The act of calling the callback associated with a watcher. |
|
|
4829 | |
|
|
4830 | =item event |
|
|
4831 | |
|
|
4832 | A change of state of some external event, such as data now being available |
|
|
4833 | for reading on a file descriptor, time having passed or simply not having |
|
|
4834 | any other events happening anymore. |
|
|
4835 | |
|
|
4836 | In libev, events are represented as single bits (such as C<EV_READ> or |
|
|
4837 | C<EV_TIMER>). |
|
|
4838 | |
|
|
4839 | =item event library |
|
|
4840 | |
|
|
4841 | A software package implementing an event model and loop. |
|
|
4842 | |
|
|
4843 | =item event loop |
|
|
4844 | |
|
|
4845 | An entity that handles and processes external events and converts them |
|
|
4846 | into callback invocations. |
|
|
4847 | |
|
|
4848 | =item event model |
|
|
4849 | |
|
|
4850 | The model used to describe how an event loop handles and processes |
|
|
4851 | watchers and events. |
|
|
4852 | |
|
|
4853 | =item pending |
|
|
4854 | |
|
|
4855 | A watcher is pending as soon as the corresponding event has been detected, |
|
|
4856 | and stops being pending as soon as the watcher will be invoked or its |
|
|
4857 | pending status is explicitly cleared by the application. |
|
|
4858 | |
|
|
4859 | A watcher can be pending, but not active. Stopping a watcher also clears |
|
|
4860 | its pending status. |
|
|
4861 | |
|
|
4862 | =item real time |
|
|
4863 | |
|
|
4864 | The physical time that is observed. It is apparently strictly monotonic :) |
|
|
4865 | |
|
|
4866 | =item wall-clock time |
|
|
4867 | |
|
|
4868 | The time and date as shown on clocks. Unlike real time, it can actually |
|
|
4869 | be wrong and jump forwards and backwards, e.g. when the you adjust your |
|
|
4870 | clock. |
|
|
4871 | |
|
|
4872 | =item watcher |
|
|
4873 | |
|
|
4874 | A data structure that describes interest in certain events. Watchers need |
|
|
4875 | to be started (attached to an event loop) before they can receive events. |
|
|
4876 | |
|
|
4877 | =item watcher invocation |
|
|
4878 | |
|
|
4879 | The act of calling the callback associated with a watcher. |
|
|
4880 | |
|
|
4881 | =back |
|
|
4882 | |
3998 | =head1 AUTHOR |
4883 | =head1 AUTHOR |
3999 | |
4884 | |
4000 | Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael Magnusson. |
4885 | Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael Magnusson. |
4001 | |
4886 | |