… | |
… | |
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 | |
… | |
… | |
75 | While this document tries to be as complete as possible in documenting |
75 | While this document tries to be as complete as possible in documenting |
76 | libev, its usage and the rationale behind its design, it is not a tutorial |
76 | libev, its usage and the rationale behind its design, it is not a tutorial |
77 | on event-based programming, nor will it introduce event-based programming |
77 | on event-based programming, nor will it introduce event-based programming |
78 | with libev. |
78 | with libev. |
79 | |
79 | |
80 | Familarity with event based programming techniques in general is assumed |
80 | Familiarity with event based programming techniques in general is assumed |
81 | throughout this document. |
81 | throughout this document. |
82 | |
82 | |
83 | =head1 ABOUT LIBEV |
83 | =head1 ABOUT LIBEV |
84 | |
84 | |
85 | 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 |
… | |
… | |
98 | =head2 FEATURES |
98 | =head2 FEATURES |
99 | |
99 | |
100 | 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 |
101 | BSD-specific C<kqueue> and the Solaris-specific event port mechanisms |
101 | BSD-specific C<kqueue> and the Solaris-specific event port mechanisms |
102 | 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 |
103 | (for C<ev_stat>), relative timers (C<ev_timer>), absolute timers |
103 | (for C<ev_stat>), Linux eventfd/signalfd (for faster and cleaner |
104 | with customised rescheduling (C<ev_periodic>), synchronous signals |
104 | inter-thread wakeup (C<ev_async>)/signal handling (C<ev_signal>)) relative |
105 | (C<ev_signal>), process status change events (C<ev_child>), and event |
105 | timers (C<ev_timer>), absolute timers with customised rescheduling |
106 | watchers dealing with the event loop mechanism itself (C<ev_idle>, |
106 | (C<ev_periodic>), synchronous signals (C<ev_signal>), process status |
107 | 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 |
108 | 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 |
109 | (C<ev_fork>). |
109 | C<ev_check> watchers) as well as file watchers (C<ev_stat>) and even |
|
|
110 | limited support for fork events (C<ev_fork>). |
110 | |
111 | |
111 | It also is quite fast (see this |
112 | It also is quite fast (see this |
112 | 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 |
113 | for example). |
114 | for example). |
114 | |
115 | |
… | |
… | |
117 | 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) |
118 | configuration will be described, which supports multiple event loops. For |
119 | configuration will be described, which supports multiple event loops. For |
119 | more info about various configuration options please have a look at |
120 | more info about various configuration options please have a look at |
120 | 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 |
121 | 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 |
122 | 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 |
123 | this argument. |
124 | this argument. |
124 | |
125 | |
125 | =head2 TIME REPRESENTATION |
126 | =head2 TIME REPRESENTATION |
126 | |
127 | |
127 | Libev represents time as a single floating point number, representing |
128 | Libev represents time as a single floating point number, representing |
128 | the (fractional) number of seconds since the (POSIX) epoch (somewhere |
129 | the (fractional) number of seconds since the (POSIX) epoch (in practise |
129 | near the beginning of 1970, details are complicated, don't ask). This |
130 | somewhere near the beginning of 1970, details are complicated, don't |
130 | type is called C<ev_tstamp>, which is what you should use too. It usually |
131 | ask). This type is called C<ev_tstamp>, which is what you should use |
131 | aliases to the C<double> type in C. When you need to do any calculations |
132 | too. It usually aliases to the C<double> type in C. When you need to do |
132 | on 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. |
|
|
134 | |
133 | 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 |
134 | throughout libev. |
136 | time differences (e.g. delays) throughout libev. |
135 | |
137 | |
136 | =head1 ERROR HANDLING |
138 | =head1 ERROR HANDLING |
137 | |
139 | |
138 | Libev knows three classes of errors: operating system errors, usage errors |
140 | Libev knows three classes of errors: operating system errors, usage errors |
139 | and internal errors (bugs). |
141 | and internal errors (bugs). |
… | |
… | |
190 | as this indicates an incompatible change. Minor versions are usually |
192 | as this indicates an incompatible change. Minor versions are usually |
191 | 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 |
192 | not a problem. |
194 | not a problem. |
193 | |
195 | |
194 | 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 |
195 | version. |
197 | version (note, however, that this will not detect ABI mismatches :). |
196 | |
198 | |
197 | assert (("libev version mismatch", |
199 | assert (("libev version mismatch", |
198 | ev_version_major () == EV_VERSION_MAJOR |
200 | ev_version_major () == EV_VERSION_MAJOR |
199 | && ev_version_minor () >= EV_VERSION_MINOR)); |
201 | && ev_version_minor () >= EV_VERSION_MINOR)); |
200 | |
202 | |
… | |
… | |
290 | |
292 | |
291 | =back |
293 | =back |
292 | |
294 | |
293 | =head1 FUNCTIONS CONTROLLING THE EVENT LOOP |
295 | =head1 FUNCTIONS CONTROLLING THE EVENT LOOP |
294 | |
296 | |
295 | 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 |
296 | 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 |
297 | I<function>). |
299 | 3 had an C<ev_loop> function colliding with the struct name). |
298 | |
300 | |
299 | 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 |
300 | supports signals and child events, and dynamically created loops which do |
302 | supports signals and child events, and dynamically created event loops |
301 | not. |
303 | which do not. |
302 | |
304 | |
303 | =over 4 |
305 | =over 4 |
304 | |
306 | |
305 | =item struct ev_loop *ev_default_loop (unsigned int flags) |
307 | =item struct ev_loop *ev_default_loop (unsigned int flags) |
306 | |
308 | |
… | |
… | |
344 | 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 |
345 | around bugs. |
347 | around bugs. |
346 | |
348 | |
347 | =item C<EVFLAG_FORKCHECK> |
349 | =item C<EVFLAG_FORKCHECK> |
348 | |
350 | |
349 | 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 |
350 | 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. |
351 | enabling this flag. |
|
|
352 | |
353 | |
353 | 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, |
354 | 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 |
355 | 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 |
356 | 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 |
… | |
… | |
362 | flag. |
363 | flag. |
363 | |
364 | |
364 | 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> |
365 | environment variable. |
366 | environment variable. |
366 | |
367 | |
|
|
368 | =item C<EVFLAG_NOINOTIFY> |
|
|
369 | |
|
|
370 | When this flag is specified, then libev will not attempt to use the |
|
|
371 | I<inotify> API for it's C<ev_stat> watchers. Apart from debugging and |
|
|
372 | testing, this flag can be useful to conserve inotify file descriptors, as |
|
|
373 | otherwise each loop using C<ev_stat> watchers consumes one inotify handle. |
|
|
374 | |
|
|
375 | =item C<EVFLAG_SIGNALFD> |
|
|
376 | |
|
|
377 | When this flag is specified, then libev will attempt to use the |
|
|
378 | I<signalfd> API for it's C<ev_signal> (and C<ev_child>) watchers. This API |
|
|
379 | delivers signals synchronously, which makes it both faster and might make |
|
|
380 | it possible to get the queued signal data. It can also simplify signal |
|
|
381 | handling with threads, as long as you properly block signals in your |
|
|
382 | threads that are not interested in handling them. |
|
|
383 | |
|
|
384 | Signalfd will not be used by default as this changes your signal mask, and |
|
|
385 | there are a lot of shoddy libraries and programs (glib's threadpool for |
|
|
386 | example) that can't properly initialise their signal masks. |
|
|
387 | |
367 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
388 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
368 | |
389 | |
369 | 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 |
370 | 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, |
371 | 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 |
… | |
… | |
394 | |
415 | |
395 | 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 |
396 | C<EV_WRITE> to C<POLLOUT | POLLERR | POLLHUP>. |
417 | C<EV_WRITE> to C<POLLOUT | POLLERR | POLLHUP>. |
397 | |
418 | |
398 | =item C<EVBACKEND_EPOLL> (value 4, Linux) |
419 | =item C<EVBACKEND_EPOLL> (value 4, Linux) |
|
|
420 | |
|
|
421 | Use the linux-specific epoll(7) interface (for both pre- and post-2.6.9 |
|
|
422 | kernels). |
399 | |
423 | |
400 | 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, |
401 | but it scales phenomenally better. While poll and select usually scale |
425 | but it scales phenomenally better. While poll and select usually scale |
402 | 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), |
403 | epoll scales either O(1) or O(active_fds). |
427 | epoll scales either O(1) or O(active_fds). |
… | |
… | |
415 | 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 |
416 | I<different> file descriptors (even already closed ones, so one cannot |
440 | I<different> file descriptors (even already closed ones, so one cannot |
417 | 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 |
418 | on SMP systems). Libev tries to counter these spurious notifications by |
442 | on SMP systems). Libev tries to counter these spurious notifications by |
419 | employing an additional generation counter and comparing that against the |
443 | employing an additional generation counter and comparing that against the |
420 | events to filter out spurious ones, recreating the set when required. |
444 | events to filter out spurious ones, recreating the set when required. Last |
|
|
445 | not least, it also refuses to work with some file descriptors which work |
|
|
446 | perfectly fine with C<select> (files, many character devices...). |
421 | |
447 | |
422 | 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 |
423 | 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 |
424 | 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 |
425 | 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 |
… | |
… | |
518 | |
544 | |
519 | It is definitely not recommended to use this flag. |
545 | It is definitely not recommended to use this flag. |
520 | |
546 | |
521 | =back |
547 | =back |
522 | |
548 | |
523 | 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, |
524 | 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 |
525 | specified, all backends in C<ev_recommended_backends ()> will be tried. |
551 | here). If none are specified, all backends in C<ev_recommended_backends |
|
|
552 | ()> will be tried. |
526 | |
553 | |
527 | Example: This is the most typical usage. |
554 | Example: This is the most typical usage. |
528 | |
555 | |
529 | if (!ev_default_loop (0)) |
556 | if (!ev_default_loop (0)) |
530 | fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?"); |
557 | fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?"); |
… | |
… | |
542 | ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE); |
569 | ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE); |
543 | |
570 | |
544 | =item struct ev_loop *ev_loop_new (unsigned int flags) |
571 | =item struct ev_loop *ev_loop_new (unsigned int flags) |
545 | |
572 | |
546 | 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 |
547 | always distinct from the default loop. Unlike the default loop, it cannot |
574 | always distinct from the default loop. |
548 | handle signal and child watchers, and attempts to do so will be greeted by |
|
|
549 | undefined behaviour (or a failed assertion if assertions are enabled). |
|
|
550 | |
575 | |
551 | 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 |
552 | 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 |
553 | default loop in the "main" or "initial" thread. |
578 | default loop in the "main" or "initial" thread. |
554 | |
579 | |
555 | 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. |
556 | |
581 | |
… | |
… | |
558 | if (!epoller) |
583 | if (!epoller) |
559 | fatal ("no epoll found here, maybe it hides under your chair"); |
584 | fatal ("no epoll found here, maybe it hides under your chair"); |
560 | |
585 | |
561 | =item ev_default_destroy () |
586 | =item ev_default_destroy () |
562 | |
587 | |
563 | Destroys the default loop again (frees all memory and kernel state |
588 | Destroys the default loop (frees all memory and kernel state etc.). None |
564 | 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 |
565 | 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 |
566 | responsibility to either stop all watchers cleanly yourself I<before> |
591 | either stop all watchers cleanly yourself I<before> calling this function, |
567 | 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 |
568 | 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). |
569 | for example). |
|
|
570 | |
594 | |
571 | 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 |
572 | 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 |
573 | as signal and child watchers) would need to be stopped manually. |
597 | as signal and child watchers) would need to be stopped manually. |
574 | |
598 | |
575 | 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 |
576 | 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 |
577 | 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 |
578 | C<ev_loop_new> and C<ev_loop_destroy>). |
602 | C<ev_loop_new> and C<ev_loop_destroy>. |
579 | |
603 | |
580 | =item ev_loop_destroy (loop) |
604 | =item ev_loop_destroy (loop) |
581 | |
605 | |
582 | 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 |
583 | earlier call to C<ev_loop_new>. |
607 | earlier call to C<ev_loop_new>. |
584 | |
608 | |
585 | =item ev_default_fork () |
609 | =item ev_default_fork () |
586 | |
610 | |
587 | 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 |
588 | 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 |
589 | 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 |
590 | 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 |
591 | 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 |
592 | 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. |
|
|
617 | |
|
|
618 | Again, you I<have> to call it on I<any> loop that you want to re-use after |
|
|
619 | a fork, I<even if you do not plan to use the loop in the parent>. This is |
|
|
620 | because some kernel interfaces *cough* I<kqueue> *cough* do funny things |
|
|
621 | during fork. |
593 | |
622 | |
594 | 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 |
595 | 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 |
596 | 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 |
|
|
626 | call it at all (in fact, C<epoll> is so badly broken that it makes a |
|
|
627 | difference, but libev will usually detect this case on its own and do a |
|
|
628 | costly reset of the backend). |
597 | |
629 | |
598 | 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 |
599 | 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 |
600 | quite nicely into a call to C<pthread_atfork>: |
632 | quite nicely into a call to C<pthread_atfork>: |
601 | |
633 | |
… | |
… | |
603 | |
635 | |
604 | =item ev_loop_fork (loop) |
636 | =item ev_loop_fork (loop) |
605 | |
637 | |
606 | 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 |
607 | 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 |
608 | 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 |
609 | entirely your own problem. |
641 | them is entirely your own problem. |
610 | |
642 | |
611 | =item int ev_is_default_loop (loop) |
643 | =item int ev_is_default_loop (loop) |
612 | |
644 | |
613 | 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 |
614 | otherwise. |
646 | otherwise. |
615 | |
647 | |
616 | =item unsigned int ev_loop_count (loop) |
648 | =item unsigned int ev_iteration (loop) |
617 | |
649 | |
618 | 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 |
619 | 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> |
620 | happily wraps around with enough iterations. |
652 | and happily wraps around with enough iterations. |
621 | |
653 | |
622 | 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 |
623 | "ticks" the number of loop iterations), as it roughly corresponds with |
655 | "ticks" the number of loop iterations), as it roughly corresponds with |
624 | 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. |
625 | |
658 | |
626 | =item unsigned int ev_loop_depth (loop) |
659 | =item unsigned int ev_depth (loop) |
627 | |
660 | |
628 | Returns the number of times C<ev_loop> was entered minus the number of |
661 | Returns the number of times C<ev_run> was entered minus the number of |
629 | times C<ev_loop> was exited, in other words, the recursion depth. |
662 | times C<ev_run> was exited, in other words, the recursion depth. |
630 | |
663 | |
631 | Outside C<ev_loop>, this number is zero. In a callback, this number is |
664 | Outside C<ev_run>, this number is zero. In a callback, this number is |
632 | C<1>, unless C<ev_loop> was invoked recursively (or from another thread), |
665 | C<1>, unless C<ev_run> was invoked recursively (or from another thread), |
633 | in which case it is higher. |
666 | in which case it is higher. |
634 | |
667 | |
635 | Leaving C<ev_loop> abnormally (setjmp/longjmp, cancelling the thread |
668 | Leaving C<ev_run> abnormally (setjmp/longjmp, cancelling the thread |
636 | etc.), doesn't count as exit. |
669 | etc.), doesn't count as "exit" - consider this as a hint to avoid such |
|
|
670 | ungentleman-like behaviour unless it's really convenient. |
637 | |
671 | |
638 | =item unsigned int ev_backend (loop) |
672 | =item unsigned int ev_backend (loop) |
639 | |
673 | |
640 | 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 |
641 | use. |
675 | use. |
… | |
… | |
650 | |
684 | |
651 | =item ev_now_update (loop) |
685 | =item ev_now_update (loop) |
652 | |
686 | |
653 | Establishes the current time by querying the kernel, updating the time |
687 | Establishes the current time by querying the kernel, updating the time |
654 | 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 |
655 | is usually done automatically within C<ev_loop ()>. |
689 | is usually done automatically within C<ev_run ()>. |
656 | |
690 | |
657 | 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 |
658 | 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 |
659 | the current time is a good idea. |
693 | the current time is a good idea. |
660 | |
694 | |
… | |
… | |
662 | |
696 | |
663 | =item ev_suspend (loop) |
697 | =item ev_suspend (loop) |
664 | |
698 | |
665 | =item ev_resume (loop) |
699 | =item ev_resume (loop) |
666 | |
700 | |
667 | 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 |
668 | 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. |
669 | |
703 | |
670 | 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 |
671 | 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 |
672 | 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 |
673 | 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> |
… | |
… | |
675 | C<ev_resume> directly afterwards to resume timer processing. |
709 | C<ev_resume> directly afterwards to resume timer processing. |
676 | |
710 | |
677 | 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 |
678 | 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 |
679 | 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 |
680 | occured while suspended). |
714 | occurred while suspended). |
681 | |
715 | |
682 | 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 |
683 | 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> |
684 | without a previous call to C<ev_suspend>. |
718 | without a previous call to C<ev_suspend>. |
685 | |
719 | |
686 | 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 |
687 | event loop time (see C<ev_now_update>). |
721 | event loop time (see C<ev_now_update>). |
688 | |
722 | |
689 | =item ev_loop (loop, int flags) |
723 | =item ev_run (loop, int flags) |
690 | |
724 | |
691 | 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 |
692 | 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 |
693 | 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>. |
694 | |
730 | |
695 | 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 |
696 | 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. |
697 | |
734 | |
698 | 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 |
699 | 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 |
700 | finished (especially in interactive programs), but having a program |
737 | finished (especially in interactive programs), but having a program |
701 | 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 |
702 | 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 |
703 | beauty. |
740 | beauty. |
704 | |
741 | |
705 | 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 |
706 | 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 |
707 | 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 |
708 | 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. |
709 | |
747 | |
710 | 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 |
711 | necessary) and will handle those and any already outstanding ones. It |
749 | necessary) and will handle those and any already outstanding ones. It |
712 | 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 |
713 | 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 |
714 | user-registered callback will be called), and will return after one |
752 | user-registered callback will be called), and will return after one |
715 | iteration of the loop. |
753 | iteration of the loop. |
716 | |
754 | |
717 | 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 |
718 | 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 |
719 | 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 |
720 | usually a better approach for this kind of thing. |
758 | usually a better approach for this kind of thing. |
721 | |
759 | |
722 | Here are the gory details of what C<ev_loop> does: |
760 | Here are the gory details of what C<ev_run> does: |
723 | |
761 | |
|
|
762 | - Increment loop depth. |
|
|
763 | - Reset the ev_break status. |
724 | - Before the first iteration, call any pending watchers. |
764 | - Before the first iteration, call any pending watchers. |
|
|
765 | LOOP: |
725 | * If EVFLAG_FORKCHECK was used, check for a fork. |
766 | - If EVFLAG_FORKCHECK was used, check for a fork. |
726 | - 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. |
727 | - Queue and call all prepare watchers. |
768 | - Queue and call all prepare watchers. |
|
|
769 | - If ev_break was called, goto FINISH. |
728 | - If we have been forked, detach and recreate the kernel state |
770 | - If we have been forked, detach and recreate the kernel state |
729 | as to not disturb the other process. |
771 | as to not disturb the other process. |
730 | - Update the kernel state with all outstanding changes. |
772 | - Update the kernel state with all outstanding changes. |
731 | - Update the "event loop time" (ev_now ()). |
773 | - Update the "event loop time" (ev_now ()). |
732 | - Calculate for how long to sleep or block, if at all |
774 | - Calculate for how long to sleep or block, if at all |
733 | (active idle watchers, EVLOOP_NONBLOCK or not having |
775 | (active idle watchers, EVRUN_NOWAIT or not having |
734 | any active watchers at all will result in not sleeping). |
776 | any active watchers at all will result in not sleeping). |
735 | - 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. |
736 | - Block the process, waiting for any events. |
779 | - Block the process, waiting for any events. |
737 | - Queue all outstanding I/O (fd) events. |
780 | - Queue all outstanding I/O (fd) events. |
738 | - 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. |
739 | - Queue all expired timers. |
782 | - Queue all expired timers. |
740 | - Queue all expired periodics. |
783 | - Queue all expired periodics. |
741 | - Unless any events are pending now, queue all idle watchers. |
784 | - Queue all idle watchers with priority higher than that of pending events. |
742 | - Queue all check watchers. |
785 | - Queue all check watchers. |
743 | - 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). |
744 | 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 |
745 | be handled here by queueing them when their watcher gets executed. |
788 | be handled here by queueing them when their watcher gets executed. |
746 | - 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 |
747 | were used, or there are no active watchers, return, otherwise |
790 | were used, or there are no active watchers, goto FINISH, otherwise |
748 | 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. |
749 | |
796 | |
750 | 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 |
751 | anymore. |
798 | anymore. |
752 | |
799 | |
753 | ... queue jobs here, make sure they register event watchers as long |
800 | ... queue jobs here, make sure they register event watchers as long |
754 | ... 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..) |
755 | ev_loop (my_loop, 0); |
802 | ev_run (my_loop, 0); |
756 | ... jobs done or somebody called unloop. yeah! |
803 | ... jobs done or somebody called unloop. yeah! |
757 | |
804 | |
758 | =item ev_unloop (loop, how) |
805 | =item ev_break (loop, how) |
759 | |
806 | |
760 | 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 |
761 | 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 |
762 | 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 |
763 | 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. |
764 | |
811 | |
765 | 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. |
766 | |
813 | |
767 | 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## |
768 | |
815 | |
769 | =item ev_ref (loop) |
816 | =item ev_ref (loop) |
770 | |
817 | |
771 | =item ev_unref (loop) |
818 | =item ev_unref (loop) |
772 | |
819 | |
773 | 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 |
774 | 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 |
775 | 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. |
776 | |
823 | |
777 | 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 |
778 | 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> |
779 | stopping it. |
827 | before stopping it. |
780 | |
828 | |
781 | 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 |
782 | 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 |
783 | 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 |
784 | 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 |
785 | 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 |
786 | 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 |
787 | before, respectively. Note also that libev might stop watchers itself |
835 | before, respectively. Note also that libev might stop watchers itself |
788 | (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> |
789 | in the callback). |
837 | in the callback). |
790 | |
838 | |
791 | 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> |
792 | running when nothing else is active. |
840 | running when nothing else is active. |
793 | |
841 | |
794 | ev_signal exitsig; |
842 | ev_signal exitsig; |
795 | ev_signal_init (&exitsig, sig_cb, SIGINT); |
843 | ev_signal_init (&exitsig, sig_cb, SIGINT); |
796 | ev_signal_start (loop, &exitsig); |
844 | ev_signal_start (loop, &exitsig); |
… | |
… | |
841 | 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>, |
842 | as this approaches the timing granularity of most systems. Note that if |
890 | as this approaches the timing granularity of most systems. Note that if |
843 | you do transactions with the outside world and you can't increase the |
891 | you do transactions with the outside world and you can't increase the |
844 | parallelity, then this setting will limit your transaction rate (if you |
892 | parallelity, then this setting will limit your transaction rate (if you |
845 | need to poll once per transaction and the I/O collect interval is 0.01, |
893 | need to poll once per transaction and the I/O collect interval is 0.01, |
846 | then you can't do more than 100 transations per second). |
894 | then you can't do more than 100 transactions per second). |
847 | |
895 | |
848 | Setting the I<timeout collect interval> can improve the opportunity for |
896 | Setting the I<timeout collect interval> can improve the opportunity for |
849 | saving power, as the program will "bundle" timer callback invocations that |
897 | saving power, as the program will "bundle" timer callback invocations that |
850 | 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 |
851 | 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 |
… | |
… | |
859 | ev_set_io_collect_interval (EV_DEFAULT_UC_ 0.01); |
907 | ev_set_io_collect_interval (EV_DEFAULT_UC_ 0.01); |
860 | |
908 | |
861 | =item ev_invoke_pending (loop) |
909 | =item ev_invoke_pending (loop) |
862 | |
910 | |
863 | This call will simply invoke all pending watchers while resetting their |
911 | This call will simply invoke all pending watchers while resetting their |
864 | pending state. Normally, C<ev_loop> does this automatically when required, |
912 | pending state. Normally, C<ev_run> does this automatically when required, |
865 | but when overriding the invoke callback this call comes handy. |
913 | but when overriding the invoke callback this call comes handy. |
866 | |
914 | |
867 | =item int ev_pending_count (loop) |
915 | =item int ev_pending_count (loop) |
868 | |
916 | |
869 | Returns the number of pending watchers - zero indicates that no watchers |
917 | Returns the number of pending watchers - zero indicates that no watchers |
870 | are pending. |
918 | are pending. |
871 | |
919 | |
872 | =item ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(EV_P)) |
920 | =item ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(EV_P)) |
873 | |
921 | |
874 | This overrides the invoke pending functionality of the loop: Instead of |
922 | This overrides the invoke pending functionality of the loop: Instead of |
875 | invoking all pending watchers when there are any, C<ev_loop> will call |
923 | invoking all pending watchers when there are any, C<ev_run> will call |
876 | this callback instead. This is useful, for example, when you want to |
924 | this callback instead. This is useful, for example, when you want to |
877 | invoke the actual watchers inside another context (another thread etc.). |
925 | invoke the actual watchers inside another context (another thread etc.). |
878 | |
926 | |
879 | If you want to reset the callback, use C<ev_invoke_pending> as new |
927 | If you want to reset the callback, use C<ev_invoke_pending> as new |
880 | callback. |
928 | callback. |
… | |
… | |
883 | |
931 | |
884 | Sometimes you want to share the same loop between multiple threads. This |
932 | Sometimes you want to share the same loop between multiple threads. This |
885 | can be done relatively simply by putting mutex_lock/unlock calls around |
933 | can be done relatively simply by putting mutex_lock/unlock calls around |
886 | each call to a libev function. |
934 | each call to a libev function. |
887 | |
935 | |
888 | However, C<ev_loop> can run an indefinite time, so it is not feasible to |
936 | However, C<ev_run> can run an indefinite time, so it is not feasible |
889 | wait for it to return. One way around this is to wake up the loop via |
937 | to wait for it to return. One way around this is to wake up the event |
890 | C<ev_unloop> and C<av_async_send>, another way is to set these I<release> |
938 | loop via C<ev_break> and C<av_async_send>, another way is to set these |
891 | and I<acquire> callbacks on the loop. |
939 | I<release> and I<acquire> callbacks on the loop. |
892 | |
940 | |
893 | When set, then C<release> will be called just before the thread is |
941 | When set, then C<release> will be called just before the thread is |
894 | suspended waiting for new events, and C<acquire> is called just |
942 | suspended waiting for new events, and C<acquire> is called just |
895 | afterwards. |
943 | afterwards. |
896 | |
944 | |
… | |
… | |
899 | |
947 | |
900 | While event loop modifications are allowed between invocations of |
948 | While event loop modifications are allowed between invocations of |
901 | C<release> and C<acquire> (that's their only purpose after all), no |
949 | C<release> and C<acquire> (that's their only purpose after all), no |
902 | modifications done will affect the event loop, i.e. adding watchers will |
950 | modifications done will affect the event loop, i.e. adding watchers will |
903 | have no effect on the set of file descriptors being watched, or the time |
951 | have no effect on the set of file descriptors being watched, or the time |
904 | waited. USe an C<ev_async> watcher to wake up C<ev_loop> when you want it |
952 | waited. Use an C<ev_async> watcher to wake up C<ev_run> when you want it |
905 | to take note of any changes you made. |
953 | to take note of any changes you made. |
906 | |
954 | |
907 | In theory, threads executing C<ev_loop> will be async-cancel safe between |
955 | In theory, threads executing C<ev_run> will be async-cancel safe between |
908 | invocations of C<release> and C<acquire>. |
956 | invocations of C<release> and C<acquire>. |
909 | |
957 | |
910 | See also the locking example in the C<THREADS> section later in this |
958 | See also the locking example in the C<THREADS> section later in this |
911 | document. |
959 | document. |
912 | |
960 | |
… | |
… | |
921 | These two functions can be used to associate arbitrary data with a loop, |
969 | These two functions can be used to associate arbitrary data with a loop, |
922 | and are intended solely for the C<invoke_pending_cb>, C<release> and |
970 | and are intended solely for the C<invoke_pending_cb>, C<release> and |
923 | C<acquire> callbacks described above, but of course can be (ab-)used for |
971 | C<acquire> callbacks described above, but of course can be (ab-)used for |
924 | any other purpose as well. |
972 | any other purpose as well. |
925 | |
973 | |
926 | =item ev_loop_verify (loop) |
974 | =item ev_verify (loop) |
927 | |
975 | |
928 | 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 |
929 | 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 |
930 | through all internal structures and checks them for validity. If anything |
978 | through all internal structures and checks them for validity. If anything |
931 | 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 |
… | |
… | |
949 | 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: |
950 | |
998 | |
951 | 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) |
952 | { |
1000 | { |
953 | ev_io_stop (w); |
1001 | ev_io_stop (w); |
954 | ev_unloop (loop, EVUNLOOP_ALL); |
1002 | ev_break (loop, EVBREAK_ALL); |
955 | } |
1003 | } |
956 | |
1004 | |
957 | struct ev_loop *loop = ev_default_loop (0); |
1005 | struct ev_loop *loop = ev_default_loop (0); |
958 | |
1006 | |
959 | ev_io stdin_watcher; |
1007 | ev_io stdin_watcher; |
960 | |
1008 | |
961 | ev_init (&stdin_watcher, my_cb); |
1009 | ev_init (&stdin_watcher, my_cb); |
962 | ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ); |
1010 | ev_io_set (&stdin_watcher, STDIN_FILENO, EV_READ); |
963 | ev_io_start (loop, &stdin_watcher); |
1011 | ev_io_start (loop, &stdin_watcher); |
964 | |
1012 | |
965 | ev_loop (loop, 0); |
1013 | ev_run (loop, 0); |
966 | |
1014 | |
967 | 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 |
968 | 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 |
969 | stack). |
1017 | stack). |
970 | |
1018 | |
… | |
… | |
1006 | =item C<EV_WRITE> |
1054 | =item C<EV_WRITE> |
1007 | |
1055 | |
1008 | 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 |
1009 | writable. |
1057 | writable. |
1010 | |
1058 | |
1011 | =item C<EV_TIMEOUT> |
1059 | =item C<EV_TIMER> |
1012 | |
1060 | |
1013 | The C<ev_timer> watcher has timed out. |
1061 | The C<ev_timer> watcher has timed out. |
1014 | |
1062 | |
1015 | =item C<EV_PERIODIC> |
1063 | =item C<EV_PERIODIC> |
1016 | |
1064 | |
… | |
… | |
1034 | |
1082 | |
1035 | =item C<EV_PREPARE> |
1083 | =item C<EV_PREPARE> |
1036 | |
1084 | |
1037 | =item C<EV_CHECK> |
1085 | =item C<EV_CHECK> |
1038 | |
1086 | |
1039 | 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 |
1040 | 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 |
1041 | 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 |
1042 | 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 |
1043 | 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 |
1044 | (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 |
1045 | C<ev_loop> from blocking). |
1093 | C<ev_run> from blocking). |
1046 | |
1094 | |
1047 | =item C<EV_EMBED> |
1095 | =item C<EV_EMBED> |
1048 | |
1096 | |
1049 | 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. |
1050 | |
1098 | |
… | |
… | |
1106 | |
1154 | |
1107 | ev_io w; |
1155 | ev_io w; |
1108 | ev_init (&w, my_cb); |
1156 | ev_init (&w, my_cb); |
1109 | ev_io_set (&w, STDIN_FILENO, EV_READ); |
1157 | ev_io_set (&w, STDIN_FILENO, EV_READ); |
1110 | |
1158 | |
1111 | =item C<ev_TYPE_set> (ev_TYPE *, [args]) |
1159 | =item C<ev_TYPE_set> (ev_TYPE *watcher, [args]) |
1112 | |
1160 | |
1113 | 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 |
1114 | 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 |
1115 | 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 |
1116 | 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 |
… | |
… | |
1129 | |
1177 | |
1130 | 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. |
1131 | |
1179 | |
1132 | ev_io_init (&w, my_cb, STDIN_FILENO, EV_READ); |
1180 | ev_io_init (&w, my_cb, STDIN_FILENO, EV_READ); |
1133 | |
1181 | |
1134 | =item C<ev_TYPE_start> (loop *, ev_TYPE *watcher) |
1182 | =item C<ev_TYPE_start> (loop, ev_TYPE *watcher) |
1135 | |
1183 | |
1136 | Starts (activates) the given watcher. Only active watchers will receive |
1184 | Starts (activates) the given watcher. Only active watchers will receive |
1137 | events. If the watcher is already active nothing will happen. |
1185 | events. If the watcher is already active nothing will happen. |
1138 | |
1186 | |
1139 | 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 |
1140 | whole section. |
1188 | whole section. |
1141 | |
1189 | |
1142 | ev_io_start (EV_DEFAULT_UC, &w); |
1190 | ev_io_start (EV_DEFAULT_UC, &w); |
1143 | |
1191 | |
1144 | =item C<ev_TYPE_stop> (loop *, ev_TYPE *watcher) |
1192 | =item C<ev_TYPE_stop> (loop, ev_TYPE *watcher) |
1145 | |
1193 | |
1146 | 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 |
1147 | the watcher was active or not). |
1195 | the watcher was active or not). |
1148 | |
1196 | |
1149 | It is possible that stopped watchers are pending - for example, |
1197 | It is possible that stopped watchers are pending - for example, |
… | |
… | |
1174 | =item ev_cb_set (ev_TYPE *watcher, callback) |
1222 | =item ev_cb_set (ev_TYPE *watcher, callback) |
1175 | |
1223 | |
1176 | 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 |
1177 | (modulo threads). |
1225 | (modulo threads). |
1178 | |
1226 | |
1179 | =item ev_set_priority (ev_TYPE *watcher, priority) |
1227 | =item ev_set_priority (ev_TYPE *watcher, int priority) |
1180 | |
1228 | |
1181 | =item int ev_priority (ev_TYPE *watcher) |
1229 | =item int ev_priority (ev_TYPE *watcher) |
1182 | |
1230 | |
1183 | 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 |
1184 | 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> |
… | |
… | |
1215 | 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 |
1216 | watcher isn't pending it does nothing and returns C<0>. |
1264 | watcher isn't pending it does nothing and returns C<0>. |
1217 | |
1265 | |
1218 | 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 |
1219 | 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. |
1220 | |
1282 | |
1221 | =back |
1283 | =back |
1222 | |
1284 | |
1223 | |
1285 | |
1224 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
1286 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
… | |
… | |
1335 | |
1397 | |
1336 | For example, to emulate how many other event libraries handle priorities, |
1398 | For example, to emulate how many other event libraries handle priorities, |
1337 | you can associate an C<ev_idle> watcher to each such watcher, and in |
1399 | you can associate an C<ev_idle> watcher to each such watcher, and in |
1338 | the normal watcher callback, you just start the idle watcher. The real |
1400 | the normal watcher callback, you just start the idle watcher. The real |
1339 | processing is done in the idle watcher callback. This causes libev to |
1401 | processing is done in the idle watcher callback. This causes libev to |
1340 | continously poll and process kernel event data for the watcher, but when |
1402 | continuously poll and process kernel event data for the watcher, but when |
1341 | the lock-out case is known to be rare (which in turn is rare :), this is |
1403 | the lock-out case is known to be rare (which in turn is rare :), this is |
1342 | workable. |
1404 | workable. |
1343 | |
1405 | |
1344 | Usually, however, the lock-out model implemented that way will perform |
1406 | Usually, however, the lock-out model implemented that way will perform |
1345 | miserably under the type of load it was designed to handle. In that case, |
1407 | miserably under the type of load it was designed to handle. In that case, |
… | |
… | |
1359 | { |
1421 | { |
1360 | // stop the I/O watcher, we received the event, but |
1422 | // stop the I/O watcher, we received the event, but |
1361 | // are not yet ready to handle it. |
1423 | // are not yet ready to handle it. |
1362 | ev_io_stop (EV_A_ w); |
1424 | ev_io_stop (EV_A_ w); |
1363 | |
1425 | |
1364 | // start the idle watcher to ahndle the actual event. |
1426 | // start the idle watcher to handle the actual event. |
1365 | // it will not be executed as long as other watchers |
1427 | // it will not be executed as long as other watchers |
1366 | // with the default priority are receiving events. |
1428 | // with the default priority are receiving events. |
1367 | ev_idle_start (EV_A_ &idle); |
1429 | ev_idle_start (EV_A_ &idle); |
1368 | } |
1430 | } |
1369 | |
1431 | |
… | |
… | |
1423 | |
1485 | |
1424 | 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 |
1425 | 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 |
1426 | C<EVBACKEND_SELECT> and C<EVBACKEND_POLL>). The same applies to file |
1488 | C<EVBACKEND_SELECT> and C<EVBACKEND_POLL>). The same applies to file |
1427 | descriptors for which non-blocking operation makes no sense (such as |
1489 | descriptors for which non-blocking operation makes no sense (such as |
1428 | files) - libev doesn't guarentee any specific behaviour in that case. |
1490 | files) - libev doesn't guarantee any specific behaviour in that case. |
1429 | |
1491 | |
1430 | 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 |
1431 | receive "spurious" readiness notifications, that is your callback might |
1493 | receive "spurious" readiness notifications, that is your callback might |
1432 | 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 |
1433 | 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 |
… | |
… | |
1498 | |
1560 | |
1499 | So when you encounter spurious, unexplained daemon exits, make sure you |
1561 | So when you encounter spurious, unexplained daemon exits, make sure you |
1500 | 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 |
1501 | somewhere, as that would have given you a big clue). |
1563 | somewhere, as that would have given you a big clue). |
1502 | |
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. |
1503 | |
1603 | |
1504 | =head3 Watcher-Specific Functions |
1604 | =head3 Watcher-Specific Functions |
1505 | |
1605 | |
1506 | =over 4 |
1606 | =over 4 |
1507 | |
1607 | |
… | |
… | |
1539 | ... |
1639 | ... |
1540 | struct ev_loop *loop = ev_default_init (0); |
1640 | struct ev_loop *loop = ev_default_init (0); |
1541 | ev_io stdin_readable; |
1641 | ev_io stdin_readable; |
1542 | 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); |
1543 | ev_io_start (loop, &stdin_readable); |
1643 | ev_io_start (loop, &stdin_readable); |
1544 | ev_loop (loop, 0); |
1644 | ev_run (loop, 0); |
1545 | |
1645 | |
1546 | |
1646 | |
1547 | =head2 C<ev_timer> - relative and optionally repeating timeouts |
1647 | =head2 C<ev_timer> - relative and optionally repeating timeouts |
1548 | |
1648 | |
1549 | 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 |
… | |
… | |
1558 | 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 |
1559 | passed (not I<at>, so on systems with very low-resolution clocks this |
1659 | passed (not I<at>, so on systems with very low-resolution clocks this |
1560 | might introduce a small delay). If multiple timers become ready during the |
1660 | might introduce a small delay). If multiple timers become ready during the |
1561 | same loop iteration then the ones with earlier time-out values are invoked |
1661 | same loop iteration then the ones with earlier time-out values are invoked |
1562 | before ones of the same priority with later time-out values (but this is |
1662 | before ones of the same priority with later time-out values (but this is |
1563 | no longer true when a callback calls C<ev_loop> recursively). |
1663 | no longer true when a callback calls C<ev_run> recursively). |
1564 | |
1664 | |
1565 | =head3 Be smart about timeouts |
1665 | =head3 Be smart about timeouts |
1566 | |
1666 | |
1567 | 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 |
1568 | 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, |
… | |
… | |
1654 | ev_tstamp timeout = last_activity + 60.; |
1754 | ev_tstamp timeout = last_activity + 60.; |
1655 | |
1755 | |
1656 | // 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 |
1657 | if (timeout < now) |
1757 | if (timeout < now) |
1658 | { |
1758 | { |
1659 | // timeout occured, take action |
1759 | // timeout occurred, take action |
1660 | } |
1760 | } |
1661 | else |
1761 | else |
1662 | { |
1762 | { |
1663 | // callback was invoked, but there was some activity, re-arm |
1763 | // callback was invoked, but there was some activity, re-arm |
1664 | // the watcher to fire in last_activity + 60, which is |
1764 | // the watcher to fire in last_activity + 60, which is |
… | |
… | |
1686 | 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 |
1687 | callback, which will "do the right thing" and start the timer: |
1787 | callback, which will "do the right thing" and start the timer: |
1688 | |
1788 | |
1689 | ev_init (timer, callback); |
1789 | ev_init (timer, callback); |
1690 | last_activity = ev_now (loop); |
1790 | last_activity = ev_now (loop); |
1691 | callback (loop, timer, EV_TIMEOUT); |
1791 | callback (loop, timer, EV_TIMER); |
1692 | |
1792 | |
1693 | 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 |
1694 | C<last_activity>, no libev calls at all: |
1794 | C<last_activity>, no libev calls at all: |
1695 | |
1795 | |
1696 | last_actiivty = ev_now (loop); |
1796 | last_activity = ev_now (loop); |
1697 | |
1797 | |
1698 | 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 |
1699 | time-out is unlikely to be triggered, much more efficient. |
1799 | time-out is unlikely to be triggered, much more efficient. |
1700 | |
1800 | |
1701 | 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 |
… | |
… | |
1739 | |
1839 | |
1740 | =head3 The special problem of time updates |
1840 | =head3 The special problem of time updates |
1741 | |
1841 | |
1742 | 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 |
1743 | 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 |
1744 | 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 |
1745 | 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 |
1746 | lots of events in one iteration. |
1846 | lots of events in one iteration. |
1747 | |
1847 | |
1748 | The relative timeouts are calculated relative to the C<ev_now ()> |
1848 | The relative timeouts are calculated relative to the C<ev_now ()> |
1749 | 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 |
… | |
… | |
1820 | 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. |
1821 | |
1921 | |
1822 | This sounds a bit complicated, see L<Be smart about timeouts>, above, for a |
1922 | This sounds a bit complicated, see L<Be smart about timeouts>, above, for a |
1823 | usage example. |
1923 | usage example. |
1824 | |
1924 | |
1825 | =item ev_timer_remaining (loop, ev_timer *) |
1925 | =item ev_tstamp ev_timer_remaining (loop, ev_timer *) |
1826 | |
1926 | |
1827 | Returns the remaining time until a timer fires. If the timer is active, |
1927 | Returns the remaining time until a timer fires. If the timer is active, |
1828 | then this time is relative to the current event loop time, otherwise it's |
1928 | then this time is relative to the current event loop time, otherwise it's |
1829 | the timeout value currently configured. |
1929 | the timeout value currently configured. |
1830 | |
1930 | |
1831 | That is, after an C<ev_timer_set (w, 5, 7)>, C<ev_timer_remaining> returns |
1931 | That is, after an C<ev_timer_set (w, 5, 7)>, C<ev_timer_remaining> returns |
1832 | C<5>. When the timer is started and one second passes, C<ev_timer_remain> |
1932 | C<5>. When the timer is started and one second passes, C<ev_timer_remaining> |
1833 | will return C<4>. When the timer expires and is restarted, it will return |
1933 | will return C<4>. When the timer expires and is restarted, it will return |
1834 | roughly C<7> (likely slightly less as callback invocation takes some time, |
1934 | roughly C<7> (likely slightly less as callback invocation takes some time, |
1835 | too), and so on. |
1935 | too), and so on. |
1836 | |
1936 | |
1837 | =item ev_tstamp repeat [read-write] |
1937 | =item ev_tstamp repeat [read-write] |
… | |
… | |
1866 | } |
1966 | } |
1867 | |
1967 | |
1868 | ev_timer mytimer; |
1968 | ev_timer mytimer; |
1869 | 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 */ |
1870 | ev_timer_again (&mytimer); /* start timer */ |
1970 | ev_timer_again (&mytimer); /* start timer */ |
1871 | ev_loop (loop, 0); |
1971 | ev_run (loop, 0); |
1872 | |
1972 | |
1873 | // 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": |
1874 | // reset the timeout to start ticking again at 10 seconds |
1974 | // reset the timeout to start ticking again at 10 seconds |
1875 | ev_timer_again (&mytimer); |
1975 | ev_timer_again (&mytimer); |
1876 | |
1976 | |
… | |
… | |
1902 | |
2002 | |
1903 | 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 |
1904 | 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 |
1905 | 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 |
1906 | 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 |
1907 | (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). |
1908 | |
2008 | |
1909 | =head3 Watcher-Specific Functions and Data Members |
2009 | =head3 Watcher-Specific Functions and Data Members |
1910 | |
2010 | |
1911 | =over 4 |
2011 | =over 4 |
1912 | |
2012 | |
… | |
… | |
2040 | Example: Call a callback every hour, or, more precisely, whenever the |
2140 | Example: Call a callback every hour, or, more precisely, whenever the |
2041 | system time is divisible by 3600. The callback invocation times have |
2141 | system time is divisible by 3600. The callback invocation times have |
2042 | potentially a lot of jitter, but good long-term stability. |
2142 | potentially a lot of jitter, but good long-term stability. |
2043 | |
2143 | |
2044 | static void |
2144 | static void |
2045 | clock_cb (struct ev_loop *loop, ev_io *w, int revents) |
2145 | clock_cb (struct ev_loop *loop, ev_periodic *w, int revents) |
2046 | { |
2146 | { |
2047 | ... 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) |
2048 | } |
2148 | } |
2049 | |
2149 | |
2050 | ev_periodic hourly_tick; |
2150 | ev_periodic hourly_tick; |
… | |
… | |
2076 | 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 |
2077 | 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 |
2078 | 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 |
2079 | normal event processing, like any other event. |
2179 | normal event processing, like any other event. |
2080 | |
2180 | |
2081 | Note that only the default loop supports registering signal watchers |
2181 | If you want signals to be delivered truly asynchronously, just use |
2082 | currently. |
2182 | C<sigaction> as you would do without libev and forget about sharing |
|
|
2183 | the signal. You can even use C<ev_async> from a signal handler to |
|
|
2184 | synchronously wake up an event loop. |
2083 | |
2185 | |
2084 | If you want signals asynchronously, just use C<sigaction> as you would |
|
|
2085 | do without libev and forget about sharing the signal. You can even use |
|
|
2086 | C<ev_async> from a signal handler to synchronously wake up an event loop. |
|
|
2087 | |
|
|
2088 | 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 | |
2089 | first watcher gets started will libev actually register something with |
2192 | When the first watcher gets started will libev actually register something |
2090 | the kernel (thus it coexists with your own signal handlers as long as you |
2193 | with the kernel (thus it coexists with your own signal handlers as long as |
2091 | don't register any with libev for the same signal). |
2194 | you don't register any with libev for the same signal). |
2092 | |
|
|
2093 | Both the signal mask state (C<sigprocmask>) and the signal handler state |
|
|
2094 | (C<sigaction>) are unspecified after starting a signal watcher (and after |
|
|
2095 | sotpping it again), that is, libev might or might not block the signal, |
|
|
2096 | and might or might not set or restore the installed signal handler. |
|
|
2097 | |
2195 | |
2098 | If possible and supported, libev will install its handlers with |
2196 | If possible and supported, libev will install its handlers with |
2099 | C<SA_RESTART> (or equivalent) behaviour enabled, so system calls should |
2197 | C<SA_RESTART> (or equivalent) behaviour enabled, so system calls should |
2100 | not be unduly interrupted. If you have a problem with system calls getting |
2198 | not be unduly interrupted. If you have a problem with system calls getting |
2101 | interrupted by signals you can block all signals in an C<ev_check> watcher |
2199 | interrupted by signals you can block all signals in an C<ev_check> watcher |
2102 | and unblock them in an C<ev_prepare> watcher. |
2200 | and unblock them in an C<ev_prepare> watcher. |
2103 | |
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. |
|
|
2230 | |
2104 | =head3 Watcher-Specific Functions and Data Members |
2231 | =head3 Watcher-Specific Functions and Data Members |
2105 | |
2232 | |
2106 | =over 4 |
2233 | =over 4 |
2107 | |
2234 | |
2108 | =item ev_signal_init (ev_signal *, callback, int signum) |
2235 | =item ev_signal_init (ev_signal *, callback, int signum) |
… | |
… | |
2123 | Example: Try to exit cleanly on SIGINT. |
2250 | Example: Try to exit cleanly on SIGINT. |
2124 | |
2251 | |
2125 | static void |
2252 | static void |
2126 | sigint_cb (struct ev_loop *loop, ev_signal *w, int revents) |
2253 | sigint_cb (struct ev_loop *loop, ev_signal *w, int revents) |
2127 | { |
2254 | { |
2128 | ev_unloop (loop, EVUNLOOP_ALL); |
2255 | ev_break (loop, EVBREAK_ALL); |
2129 | } |
2256 | } |
2130 | |
2257 | |
2131 | ev_signal signal_watcher; |
2258 | ev_signal signal_watcher; |
2132 | ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
2259 | ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
2133 | ev_signal_start (loop, &signal_watcher); |
2260 | ev_signal_start (loop, &signal_watcher); |
… | |
… | |
2519 | |
2646 | |
2520 | 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: |
2521 | prepare watchers get invoked before the process blocks and check watchers |
2648 | prepare watchers get invoked before the process blocks and check watchers |
2522 | afterwards. |
2649 | afterwards. |
2523 | |
2650 | |
2524 | 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 |
2525 | 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> |
2526 | watchers. Other loops than the current one are fine, however. The |
2653 | watchers. Other loops than the current one are fine, however. The |
2527 | 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 |
2528 | 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, |
2529 | 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 |
… | |
… | |
2697 | |
2824 | |
2698 | if (timeout >= 0) |
2825 | if (timeout >= 0) |
2699 | // create/start timer |
2826 | // create/start timer |
2700 | |
2827 | |
2701 | // poll |
2828 | // poll |
2702 | ev_loop (EV_A_ 0); |
2829 | ev_run (EV_A_ 0); |
2703 | |
2830 | |
2704 | // stop timer again |
2831 | // stop timer again |
2705 | if (timeout >= 0) |
2832 | if (timeout >= 0) |
2706 | ev_timer_stop (EV_A_ &to); |
2833 | ev_timer_stop (EV_A_ &to); |
2707 | |
2834 | |
… | |
… | |
2785 | 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). |
2786 | |
2913 | |
2787 | =item ev_embed_sweep (loop, ev_embed *) |
2914 | =item ev_embed_sweep (loop, ev_embed *) |
2788 | |
2915 | |
2789 | 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 |
2790 | 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 |
2791 | appropriate way for embedded loops. |
2918 | appropriate way for embedded loops. |
2792 | |
2919 | |
2793 | =item struct ev_loop *other [read-only] |
2920 | =item struct ev_loop *other [read-only] |
2794 | |
2921 | |
2795 | The embedded event loop. |
2922 | The embedded event loop. |
… | |
… | |
2855 | 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 |
2856 | handlers will be invoked, too, of course. |
2983 | handlers will be invoked, too, of course. |
2857 | |
2984 | |
2858 | =head3 The special problem of life after fork - how is it possible? |
2985 | =head3 The special problem of life after fork - how is it possible? |
2859 | |
2986 | |
2860 | Most uses of C<fork()> consist of forking, then some simple calls to ste |
2987 | Most uses of C<fork()> consist of forking, then some simple calls to set |
2861 | up/change the process environment, followed by a call to C<exec()>. This |
2988 | up/change the process environment, followed by a call to C<exec()>. This |
2862 | sequence should be handled by libev without any problems. |
2989 | sequence should be handled by libev without any problems. |
2863 | |
2990 | |
2864 | This changes when the application actually wants to do event handling |
2991 | This changes when the application actually wants to do event handling |
2865 | in the child, or both parent in child, in effect "continuing" after the |
2992 | in the child, or both parent in child, in effect "continuing" after the |
… | |
… | |
2899 | believe me. |
3026 | believe me. |
2900 | |
3027 | |
2901 | =back |
3028 | =back |
2902 | |
3029 | |
2903 | |
3030 | |
2904 | =head2 C<ev_async> - how to wake up another event loop |
3031 | =head2 C<ev_async> - how to wake up an event loop |
2905 | |
3032 | |
2906 | 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 |
2907 | asynchronous sources such as signal handlers (as opposed to multiple event |
3034 | asynchronous sources such as signal handlers (as opposed to multiple event |
2908 | loops - those are of course safe to use in different threads). |
3035 | loops - those are of course safe to use in different threads). |
2909 | |
3036 | |
2910 | 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, |
2911 | 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> |
2912 | 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 |
2913 | 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. |
2914 | safe. |
|
|
2915 | |
3041 | |
2916 | 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, |
2917 | too, are asynchronous in nature, and signals, too, will be compressed |
3043 | too, are asynchronous in nature, and signals, too, will be compressed |
2918 | (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 |
2919 | C<ev_async_sent> calls). |
3045 | C<ev_async_sent> calls). |
… | |
… | |
2924 | =head3 Queueing |
3050 | =head3 Queueing |
2925 | |
3051 | |
2926 | 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 |
2927 | 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 |
2928 | 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 |
2929 | need elaborate support such as pthreads. |
3055 | need elaborate support such as pthreads or unportable memory access |
|
|
3056 | semantics. |
2930 | |
3057 | |
2931 | 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 |
2932 | 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 |
2933 | queue: |
3060 | queue: |
2934 | |
3061 | |
… | |
… | |
3073 | |
3200 | |
3074 | 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 |
3075 | 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 |
3076 | repeat = 0) will be started. C<0> is a valid timeout. |
3203 | repeat = 0) will be started. C<0> is a valid timeout. |
3077 | |
3204 | |
3078 | 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 |
3079 | 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 |
3080 | 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> |
3081 | 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> |
3082 | 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 |
3083 | events precedence. |
3210 | events precedence. |
3084 | |
3211 | |
3085 | 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. |
3086 | |
3213 | |
3087 | static void stdin_ready (int revents, void *arg) |
3214 | static void stdin_ready (int revents, void *arg) |
3088 | { |
3215 | { |
3089 | if (revents & EV_READ) |
3216 | if (revents & EV_READ) |
3090 | /* stdin might have data for us, joy! */; |
3217 | /* stdin might have data for us, joy! */; |
3091 | else if (revents & EV_TIMEOUT) |
3218 | else if (revents & EV_TIMER) |
3092 | /* doh, nothing entered */; |
3219 | /* doh, nothing entered */; |
3093 | } |
3220 | } |
3094 | |
3221 | |
3095 | ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
3222 | ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
3096 | |
3223 | |
3097 | =item ev_feed_event (struct ev_loop *, watcher *, int revents) |
|
|
3098 | |
|
|
3099 | Feeds the given event set into the event loop, as if the specified event |
|
|
3100 | had happened for the specified watcher (which must be a pointer to an |
|
|
3101 | initialised but not necessarily started event watcher). |
|
|
3102 | |
|
|
3103 | =item ev_feed_fd_event (struct ev_loop *, int fd, int revents) |
3224 | =item ev_feed_fd_event (loop, int fd, int revents) |
3104 | |
3225 | |
3105 | 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 |
3106 | the given events it. |
3227 | the given events it. |
3107 | |
3228 | |
3108 | =item ev_feed_signal_event (struct ev_loop *loop, int signum) |
3229 | =item ev_feed_signal_event (loop, int signum) |
3109 | |
3230 | |
3110 | 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 |
3111 | loop!). |
3232 | loop!). |
3112 | |
3233 | |
3113 | =back |
3234 | =back |
… | |
… | |
3193 | |
3314 | |
3194 | =over 4 |
3315 | =over 4 |
3195 | |
3316 | |
3196 | =item ev::TYPE::TYPE () |
3317 | =item ev::TYPE::TYPE () |
3197 | |
3318 | |
3198 | =item ev::TYPE::TYPE (struct ev_loop *) |
3319 | =item ev::TYPE::TYPE (loop) |
3199 | |
3320 | |
3200 | =item ev::TYPE::~TYPE |
3321 | =item ev::TYPE::~TYPE |
3201 | |
3322 | |
3202 | The constructor (optionally) takes an event loop to associate the watcher |
3323 | The constructor (optionally) takes an event loop to associate the watcher |
3203 | with. If it is omitted, it will use C<EV_DEFAULT>. |
3324 | with. If it is omitted, it will use C<EV_DEFAULT>. |
… | |
… | |
3236 | myclass obj; |
3357 | myclass obj; |
3237 | ev::io iow; |
3358 | ev::io iow; |
3238 | iow.set <myclass, &myclass::io_cb> (&obj); |
3359 | iow.set <myclass, &myclass::io_cb> (&obj); |
3239 | |
3360 | |
3240 | =item w->set (object *) |
3361 | =item w->set (object *) |
3241 | |
|
|
3242 | This is an B<experimental> feature that might go away in a future version. |
|
|
3243 | |
3362 | |
3244 | 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 |
3245 | 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 |
3246 | functor objects without having to manually specify the C<operator ()> all |
3365 | functor objects without having to manually specify the C<operator ()> all |
3247 | 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 |
… | |
… | |
3280 | Example: Use a plain function as callback. |
3399 | Example: Use a plain function as callback. |
3281 | |
3400 | |
3282 | static void io_cb (ev::io &w, int revents) { } |
3401 | static void io_cb (ev::io &w, int revents) { } |
3283 | iow.set <io_cb> (); |
3402 | iow.set <io_cb> (); |
3284 | |
3403 | |
3285 | =item w->set (struct ev_loop *) |
3404 | =item w->set (loop) |
3286 | |
3405 | |
3287 | 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 |
3288 | do this when the watcher is inactive (and not pending either). |
3407 | do this when the watcher is inactive (and not pending either). |
3289 | |
3408 | |
3290 | =item w->set ([arguments]) |
3409 | =item w->set ([arguments]) |
3291 | |
3410 | |
3292 | 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 |
3293 | 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 |
3294 | automatically stopped and restarted when reconfiguring it with this |
3413 | C counterpart, an active watcher gets automatically stopped and restarted |
3295 | method. |
3414 | when reconfiguring it with this method. |
3296 | |
3415 | |
3297 | =item w->start () |
3416 | =item w->start () |
3298 | |
3417 | |
3299 | 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 |
3300 | constructor already stores the event loop. |
3419 | constructor already stores the event loop. |
3301 | |
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 | |
3302 | =item w->stop () |
3427 | =item w->stop () |
3303 | |
3428 | |
3304 | 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. |
3305 | |
3430 | |
3306 | =item w->again () (C<ev::timer>, C<ev::periodic> only) |
3431 | =item w->again () (C<ev::timer>, C<ev::periodic> only) |
… | |
… | |
3318 | |
3443 | |
3319 | =back |
3444 | =back |
3320 | |
3445 | |
3321 | =back |
3446 | =back |
3322 | |
3447 | |
3323 | 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 |
3324 | the constructor. |
3449 | watchers in the constructor. |
3325 | |
3450 | |
3326 | class myclass |
3451 | class myclass |
3327 | { |
3452 | { |
3328 | 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); |
3329 | ev::idle idle; void idle_cb (ev::idle &w, int revents); |
3455 | ev::idle idle; void idle_cb (ev::idle &w, int revents); |
3330 | |
3456 | |
3331 | myclass (int fd) |
3457 | myclass (int fd) |
3332 | { |
3458 | { |
3333 | io .set <myclass, &myclass::io_cb > (this); |
3459 | io .set <myclass, &myclass::io_cb > (this); |
|
|
3460 | io2 .set <myclass, &myclass::io2_cb > (this); |
3334 | idle.set <myclass, &myclass::idle_cb> (this); |
3461 | idle.set <myclass, &myclass::idle_cb> (this); |
3335 | |
3462 | |
3336 | 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 |
3337 | } |
3467 | } |
3338 | }; |
3468 | }; |
3339 | |
3469 | |
3340 | |
3470 | |
3341 | =head1 OTHER LANGUAGE BINDINGS |
3471 | =head1 OTHER LANGUAGE BINDINGS |
… | |
… | |
3387 | =item Ocaml |
3517 | =item Ocaml |
3388 | |
3518 | |
3389 | 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 |
3390 | L<http://modeemi.cs.tut.fi/~flux/software/ocaml-ev/>. |
3520 | L<http://modeemi.cs.tut.fi/~flux/software/ocaml-ev/>. |
3391 | |
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 | |
3392 | =back |
3528 | =back |
3393 | |
3529 | |
3394 | |
3530 | |
3395 | =head1 MACRO MAGIC |
3531 | =head1 MACRO MAGIC |
3396 | |
3532 | |
… | |
… | |
3409 | 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, |
3410 | C<EV_A_> is used when other arguments are following. Example: |
3546 | C<EV_A_> is used when other arguments are following. Example: |
3411 | |
3547 | |
3412 | ev_unref (EV_A); |
3548 | ev_unref (EV_A); |
3413 | ev_timer_add (EV_A_ watcher); |
3549 | ev_timer_add (EV_A_ watcher); |
3414 | ev_loop (EV_A_ 0); |
3550 | ev_run (EV_A_ 0); |
3415 | |
3551 | |
3416 | 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, |
3417 | which is often provided by the following macro. |
3553 | which is often provided by the following macro. |
3418 | |
3554 | |
3419 | =item C<EV_P>, C<EV_P_> |
3555 | =item C<EV_P>, C<EV_P_> |
… | |
… | |
3459 | } |
3595 | } |
3460 | |
3596 | |
3461 | ev_check check; |
3597 | ev_check check; |
3462 | ev_check_init (&check, check_cb); |
3598 | ev_check_init (&check, check_cb); |
3463 | ev_check_start (EV_DEFAULT_ &check); |
3599 | ev_check_start (EV_DEFAULT_ &check); |
3464 | ev_loop (EV_DEFAULT_ 0); |
3600 | ev_run (EV_DEFAULT_ 0); |
3465 | |
3601 | |
3466 | =head1 EMBEDDING |
3602 | =head1 EMBEDDING |
3467 | |
3603 | |
3468 | Libev can (and often is) directly embedded into host |
3604 | Libev can (and often is) directly embedded into host |
3469 | applications. Examples of applications that embed it include the Deliantra |
3605 | applications. Examples of applications that embed it include the Deliantra |
… | |
… | |
3549 | libev.m4 |
3685 | libev.m4 |
3550 | |
3686 | |
3551 | =head2 PREPROCESSOR SYMBOLS/MACROS |
3687 | =head2 PREPROCESSOR SYMBOLS/MACROS |
3552 | |
3688 | |
3553 | 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 |
3554 | 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 |
3555 | 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. |
3556 | |
3699 | |
3557 | =over 4 |
3700 | =over 4 |
3558 | |
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 | |
3559 | =item EV_STANDALONE |
3718 | =item EV_STANDALONE (h) |
3560 | |
3719 | |
3561 | 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 |
3562 | 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 |
3563 | implementations for some libevent functions (such as logging, which is not |
3722 | implementations for some libevent functions (such as logging, which is not |
3564 | 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 |
3565 | 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. |
3566 | |
3725 | |
3567 | In stanbdalone mode, libev will still try to automatically deduce the |
3726 | In standalone mode, libev will still try to automatically deduce the |
3568 | configuration, but has to be more conservative. |
3727 | configuration, but has to be more conservative. |
3569 | |
3728 | |
3570 | =item EV_USE_MONOTONIC |
3729 | =item EV_USE_MONOTONIC |
3571 | |
3730 | |
3572 | 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 |
… | |
… | |
3637 | 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 |
3638 | 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, |
3639 | 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 |
3640 | on win32. Should not be defined on non-win32 platforms. |
3799 | on win32. Should not be defined on non-win32 platforms. |
3641 | |
3800 | |
3642 | =item EV_FD_TO_WIN32_HANDLE |
3801 | =item EV_FD_TO_WIN32_HANDLE(fd) |
3643 | |
3802 | |
3644 | 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 |
3645 | file descriptors to socket handles. When not defining this symbol (the |
3804 | file descriptors to socket handles. When not defining this symbol (the |
3646 | default), then libev will call C<_get_osfhandle>, which is usually |
3805 | default), then libev will call C<_get_osfhandle>, which is usually |
3647 | correct. In some cases, programs use their own file descriptor management, |
3806 | correct. In some cases, programs use their own file descriptor management, |
3648 | 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. |
3649 | |
3822 | |
3650 | =item EV_USE_POLL |
3823 | =item EV_USE_POLL |
3651 | |
3824 | |
3652 | 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) |
3653 | backend. Otherwise it will be enabled on non-win32 platforms. It |
3826 | backend. Otherwise it will be enabled on non-win32 platforms. It |
… | |
… | |
3700 | 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. |
3701 | |
3874 | |
3702 | 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> |
3703 | (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. |
3704 | |
3877 | |
3705 | =item EV_H |
3878 | =item EV_H (h) |
3706 | |
3879 | |
3707 | 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 |
3708 | 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 |
3709 | 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. |
3710 | |
3883 | |
3711 | =item EV_CONFIG_H |
3884 | =item EV_CONFIG_H (h) |
3712 | |
3885 | |
3713 | 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 |
3714 | 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 |
3715 | C<EV_H>, above. |
3888 | C<EV_H>, above. |
3716 | |
3889 | |
3717 | =item EV_EVENT_H |
3890 | =item EV_EVENT_H (h) |
3718 | |
3891 | |
3719 | 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 |
3720 | 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">. |
3721 | |
3894 | |
3722 | =item EV_PROTOTYPES |
3895 | =item EV_PROTOTYPES (h) |
3723 | |
3896 | |
3724 | 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 |
3725 | 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 |
3726 | occasionally useful if you want to provide your own wrapper functions |
3899 | occasionally useful if you want to provide your own wrapper functions |
3727 | around libev functions. |
3900 | around libev functions. |
… | |
… | |
3749 | fine. |
3922 | fine. |
3750 | |
3923 | |
3751 | If your embedding application does not need any priorities, defining these |
3924 | If your embedding application does not need any priorities, defining these |
3752 | both to C<0> will save some memory and CPU. |
3925 | both to C<0> will save some memory and CPU. |
3753 | |
3926 | |
3754 | =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. |
3755 | |
3930 | |
3756 | 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 |
3757 | 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 |
3758 | code. |
3933 | is not. Disabling watcher types mainly saves code size. |
3759 | |
3934 | |
3760 | =item EV_IDLE_ENABLE |
3935 | =item EV_FEATURES |
3761 | |
|
|
3762 | If undefined or defined to be C<1>, then idle watchers are supported. If |
|
|
3763 | defined to be C<0>, then they are not. Disabling them saves a few kB of |
|
|
3764 | code. |
|
|
3765 | |
|
|
3766 | =item EV_EMBED_ENABLE |
|
|
3767 | |
|
|
3768 | If undefined or defined to be C<1>, then embed watchers are supported. If |
|
|
3769 | defined to be C<0>, then they are not. Embed watchers rely on most other |
|
|
3770 | watcher types, which therefore must not be disabled. |
|
|
3771 | |
|
|
3772 | =item EV_STAT_ENABLE |
|
|
3773 | |
|
|
3774 | If undefined or defined to be C<1>, then stat watchers are supported. If |
|
|
3775 | defined to be C<0>, then they are not. |
|
|
3776 | |
|
|
3777 | =item EV_FORK_ENABLE |
|
|
3778 | |
|
|
3779 | If undefined or defined to be C<1>, then fork watchers are supported. If |
|
|
3780 | defined to be C<0>, then they are not. |
|
|
3781 | |
|
|
3782 | =item EV_ASYNC_ENABLE |
|
|
3783 | |
|
|
3784 | If undefined or defined to be C<1>, then async watchers are supported. If |
|
|
3785 | defined to be C<0>, then they are not. |
|
|
3786 | |
|
|
3787 | =item EV_MINIMAL |
|
|
3788 | |
3936 | |
3789 | 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 |
3790 | speed (but with the full API), define this symbol to C<1>. Currently this |
3938 | speed (but with the full API), you can define this symbol to request |
3791 | is used to override some inlining decisions, saves roughly 30% code size |
3939 | certain subsets of functionality. The default is to enable all features |
3792 | on amd64. It also selects a much smaller 2-heap for timer management over |
3940 | that can be enabled on the platform. |
3793 | the default 4-heap. |
|
|
3794 | |
3941 | |
3795 | You can save even more by disabling watcher types you do not need |
3942 | A typical way to use this symbol is to define it to C<0> (or to a bitset |
3796 | and setting C<EV_MAXPRI> == C<EV_MINPRI>. Also, disabling C<assert> |
3943 | with some broad features you want) and then selectively re-enable |
3797 | (C<-DNDEBUG>) will usually reduce code size a lot. |
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: |
3798 | |
3947 | |
3799 | Defining C<EV_MINIMAL> to C<2> will additionally reduce the core API to |
3948 | #define EV_FEATURES 0 |
3800 | provide a bare-bones event library. See C<ev.h> for details on what parts |
3949 | #define EV_MULTIPLICITY 1 |
3801 | of the API are still available, and do not complain if this subset changes |
3950 | #define EV_USE_POLL 1 |
3802 | over time. |
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. |
3803 | |
4036 | |
3804 | =item EV_PID_HASHSIZE |
4037 | =item EV_PID_HASHSIZE |
3805 | |
4038 | |
3806 | 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 |
3807 | 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), |
3808 | 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 |
3809 | increase this value (I<must> be a power of two). |
4042 | might want to increase this value (I<must> be a power of two). |
3810 | |
4043 | |
3811 | =item EV_INOTIFY_HASHSIZE |
4044 | =item EV_INOTIFY_HASHSIZE |
3812 | |
4045 | |
3813 | 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 |
3814 | 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> |
3815 | 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 |
3816 | 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 |
3817 | two). |
4050 | power of two). |
3818 | |
4051 | |
3819 | =item EV_USE_4HEAP |
4052 | =item EV_USE_4HEAP |
3820 | |
4053 | |
3821 | 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 |
3822 | 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 |
3823 | 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 |
3824 | faster performance with many (thousands) of watchers. |
4057 | faster performance with many (thousands) of watchers. |
3825 | |
4058 | |
3826 | 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 |
3827 | (disabled). |
4060 | will be C<0>. |
3828 | |
4061 | |
3829 | =item EV_HEAP_CACHE_AT |
4062 | =item EV_HEAP_CACHE_AT |
3830 | |
4063 | |
3831 | 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 |
3832 | 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 |
3833 | 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>), |
3834 | 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, |
3835 | but avoids random read accesses on heap changes. This improves performance |
4068 | but avoids random read accesses on heap changes. This improves performance |
3836 | noticeably with many (hundreds) of watchers. |
4069 | noticeably with many (hundreds) of watchers. |
3837 | |
4070 | |
3838 | 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 |
3839 | (disabled). |
4072 | will be C<0>. |
3840 | |
4073 | |
3841 | =item EV_VERIFY |
4074 | =item EV_VERIFY |
3842 | |
4075 | |
3843 | Controls how much internal verification (see C<ev_loop_verify ()>) will |
4076 | Controls how much internal verification (see C<ev_verify ()>) will |
3844 | 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 |
3845 | 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 |
3846 | 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 |
3847 | 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 |
3848 | verification code will be called very frequently, which will slow down |
4081 | verification code will be called very frequently, which will slow down |
3849 | libev considerably. |
4082 | libev considerably. |
3850 | |
4083 | |
3851 | 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 |
3852 | C<0>. |
4085 | will be C<0>. |
3853 | |
4086 | |
3854 | =item EV_COMMON |
4087 | =item EV_COMMON |
3855 | |
4088 | |
3856 | 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 |
3857 | 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 |
3858 | 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, |
3859 | though, and it must be identical each time. |
4092 | though, and it must be identical each time. |
3860 | |
4093 | |
3861 | For example, the perl EV module uses something like this: |
4094 | For example, the perl EV module uses something like this: |
3862 | |
4095 | |
… | |
… | |
3915 | file. |
4148 | file. |
3916 | |
4149 | |
3917 | 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 |
3918 | that everybody includes and which overrides some configure choices: |
4151 | that everybody includes and which overrides some configure choices: |
3919 | |
4152 | |
3920 | #define EV_MINIMAL 1 |
4153 | #define EV_FEATURES 8 |
3921 | #define EV_USE_POLL 0 |
4154 | #define EV_USE_SELECT 1 |
3922 | #define EV_MULTIPLICITY 0 |
|
|
3923 | #define EV_PERIODIC_ENABLE 0 |
4155 | #define EV_PREPARE_ENABLE 1 |
|
|
4156 | #define EV_IDLE_ENABLE 1 |
3924 | #define EV_STAT_ENABLE 0 |
4157 | #define EV_SIGNAL_ENABLE 1 |
3925 | #define EV_FORK_ENABLE 0 |
4158 | #define EV_CHILD_ENABLE 1 |
|
|
4159 | #define EV_USE_STDEXCEPT 0 |
3926 | #define EV_CONFIG_H <config.h> |
4160 | #define EV_CONFIG_H <config.h> |
3927 | #define EV_MINPRI 0 |
|
|
3928 | #define EV_MAXPRI 0 |
|
|
3929 | |
4161 | |
3930 | #include "ev++.h" |
4162 | #include "ev++.h" |
3931 | |
4163 | |
3932 | 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: |
3933 | |
4165 | |
… | |
… | |
4064 | userdata *u = ev_userdata (EV_A); |
4296 | userdata *u = ev_userdata (EV_A); |
4065 | pthread_mutex_lock (&u->lock); |
4297 | pthread_mutex_lock (&u->lock); |
4066 | } |
4298 | } |
4067 | |
4299 | |
4068 | The event loop thread first acquires the mutex, and then jumps straight |
4300 | The event loop thread first acquires the mutex, and then jumps straight |
4069 | into C<ev_loop>: |
4301 | into C<ev_run>: |
4070 | |
4302 | |
4071 | void * |
4303 | void * |
4072 | l_run (void *thr_arg) |
4304 | l_run (void *thr_arg) |
4073 | { |
4305 | { |
4074 | struct ev_loop *loop = (struct ev_loop *)thr_arg; |
4306 | struct ev_loop *loop = (struct ev_loop *)thr_arg; |
4075 | |
4307 | |
4076 | l_acquire (EV_A); |
4308 | l_acquire (EV_A); |
4077 | pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0); |
4309 | pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0); |
4078 | ev_loop (EV_A_ 0); |
4310 | ev_run (EV_A_ 0); |
4079 | l_release (EV_A); |
4311 | l_release (EV_A); |
4080 | |
4312 | |
4081 | return 0; |
4313 | return 0; |
4082 | } |
4314 | } |
4083 | |
4315 | |
… | |
… | |
4135 | |
4367 | |
4136 | =head3 COROUTINES |
4368 | =head3 COROUTINES |
4137 | |
4369 | |
4138 | Libev is very accommodating to coroutines ("cooperative threads"): |
4370 | Libev is very accommodating to coroutines ("cooperative threads"): |
4139 | libev fully supports nesting calls to its functions from different |
4371 | libev fully supports nesting calls to its functions from different |
4140 | 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 |
4141 | different coroutines, and switch freely between both coroutines running |
4373 | different coroutines, and switch freely between both coroutines running |
4142 | the loop, as long as you don't confuse yourself). The only exception is |
4374 | the loop, as long as you don't confuse yourself). The only exception is |
4143 | that you must not do this from C<ev_periodic> reschedule callbacks. |
4375 | that you must not do this from C<ev_periodic> reschedule callbacks. |
4144 | |
4376 | |
4145 | 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 |
4146 | 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 |
4147 | they do not call any callbacks. |
4379 | they do not call any callbacks. |
4148 | |
4380 | |
4149 | =head2 COMPILER WARNINGS |
4381 | =head2 COMPILER WARNINGS |
4150 | |
4382 | |
4151 | 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 |
… | |
… | |
4162 | maintainable. |
4394 | maintainable. |
4163 | |
4395 | |
4164 | 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 |
4165 | 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 |
4166 | 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 |
4167 | warnings that resulted an extreme number of false positives. These have |
4399 | warnings that resulted in an extreme number of false positives. These have |
4168 | 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 |
4169 | such buggy versions. |
4401 | such buggy versions. |
4170 | |
4402 | |
4171 | While libev is written to generate as few warnings as possible, |
4403 | While libev is written to generate as few warnings as possible, |
4172 | "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 |
… | |
… | |
4208 | I suggest using suppression lists. |
4440 | I suggest using suppression lists. |
4209 | |
4441 | |
4210 | |
4442 | |
4211 | =head1 PORTABILITY NOTES |
4443 | =head1 PORTABILITY NOTES |
4212 | |
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 | |
4213 | =head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS |
4528 | =head2 WIN32 PLATFORM LIMITATIONS AND WORKAROUNDS |
|
|
4529 | |
|
|
4530 | =head3 General issues |
4214 | |
4531 | |
4215 | 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 |
4216 | 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 |
4217 | model. Libev still offers limited functionality on this platform in |
4534 | model. Libev still offers limited functionality on this platform in |
4218 | 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 |
4219 | descriptors. This only applies when using Win32 natively, not when using |
4536 | descriptors. This only applies when using Win32 natively, not when using |
4220 | 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. |
4221 | |
4540 | |
4222 | Lifting these limitations would basically require the full |
4541 | Lifting these limitations would basically require the full |
4223 | 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, |
4224 | 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 |
4225 | 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). |
4226 | |
4545 | |
4227 | There is no supported compilation method available on windows except |
4546 | There is no supported compilation method available on windows except |
4228 | embedding it into other applications. |
4547 | embedding it into other applications. |
4229 | |
4548 | |
4230 | Sensible signal handling is officially unsupported by Microsoft - libev |
4549 | Sensible signal handling is officially unsupported by Microsoft - libev |
… | |
… | |
4258 | 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!): |
4259 | |
4578 | |
4260 | #include "evwrap.h" |
4579 | #include "evwrap.h" |
4261 | #include "ev.c" |
4580 | #include "ev.c" |
4262 | |
4581 | |
4263 | =over 4 |
|
|
4264 | |
|
|
4265 | =item The winsocket select function |
4582 | =head3 The winsocket C<select> function |
4266 | |
4583 | |
4267 | 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 |
4268 | 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 |
4269 | also extremely buggy). This makes select very inefficient, and also |
4586 | also extremely buggy). This makes select very inefficient, and also |
4270 | requires a mapping from file descriptors to socket handles (the Microsoft |
4587 | requires a mapping from file descriptors to socket handles (the Microsoft |
… | |
… | |
4279 | #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 */ |
4280 | |
4597 | |
4281 | 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 |
4282 | complexity in the O(n²) range when using win32. |
4599 | complexity in the O(n²) range when using win32. |
4283 | |
4600 | |
4284 | =item Limited number of file descriptors |
4601 | =head3 Limited number of file descriptors |
4285 | |
4602 | |
4286 | Windows has numerous arbitrary (and low) limits on things. |
4603 | Windows has numerous arbitrary (and low) limits on things. |
4287 | |
4604 | |
4288 | 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 |
4289 | 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 |
… | |
… | |
4304 | runtime libraries. This might get you to about C<512> or C<2048> sockets |
4621 | runtime libraries. This might get you to about C<512> or C<2048> sockets |
4305 | (depending on windows version and/or the phase of the moon). To get more, |
4622 | (depending on windows version and/or the phase of the moon). To get more, |
4306 | you need to wrap all I/O functions and provide your own fd management, but |
4623 | you need to wrap all I/O functions and provide your own fd management, but |
4307 | the cost of calling select (O(n²)) will likely make this unworkable. |
4624 | the cost of calling select (O(n²)) will likely make this unworkable. |
4308 | |
4625 | |
4309 | =back |
|
|
4310 | |
|
|
4311 | =head2 PORTABILITY REQUIREMENTS |
4626 | =head2 PORTABILITY REQUIREMENTS |
4312 | |
4627 | |
4313 | 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 |
4314 | backend-specific APIs, libev relies on a few additional extensions: |
4629 | backend-specific APIs, libev relies on a few additional extensions: |
4315 | |
4630 | |
… | |
… | |
4353 | watchers. |
4668 | watchers. |
4354 | |
4669 | |
4355 | =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 |
4356 | |
4671 | |
4357 | 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 |
4358 | 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 |
4359 | 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 |
4360 | implementations implementing IEEE 754, which is basically all existing |
4676 | implementations using IEEE 754, which is basically all existing ones. With |
4361 | ones. With IEEE 754 doubles, you get microsecond accuracy until at least |
4677 | IEEE 754 doubles, you get microsecond accuracy until at least 2200. |
4362 | 2200. |
|
|
4363 | |
4678 | |
4364 | =back |
4679 | =back |
4365 | |
4680 | |
4366 | If you know of other additional requirements drop me a note. |
4681 | If you know of other additional requirements drop me a note. |
4367 | |
4682 | |
… | |
… | |
4435 | involves iterating over all running async watchers or all signal numbers. |
4750 | involves iterating over all running async watchers or all signal numbers. |
4436 | |
4751 | |
4437 | =back |
4752 | =back |
4438 | |
4753 | |
4439 | |
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 | |
4440 | =head1 GLOSSARY |
4807 | =head1 GLOSSARY |
4441 | |
4808 | |
4442 | =over 4 |
4809 | =over 4 |
4443 | |
4810 | |
4444 | =item active |
4811 | =item active |
… | |
… | |
4465 | A change of state of some external event, such as data now being available |
4832 | A change of state of some external event, such as data now being available |
4466 | for reading on a file descriptor, time having passed or simply not having |
4833 | for reading on a file descriptor, time having passed or simply not having |
4467 | any other events happening anymore. |
4834 | any other events happening anymore. |
4468 | |
4835 | |
4469 | In libev, events are represented as single bits (such as C<EV_READ> or |
4836 | In libev, events are represented as single bits (such as C<EV_READ> or |
4470 | C<EV_TIMEOUT>). |
4837 | C<EV_TIMER>). |
4471 | |
4838 | |
4472 | =item event library |
4839 | =item event library |
4473 | |
4840 | |
4474 | A software package implementing an event model and loop. |
4841 | A software package implementing an event model and loop. |
4475 | |
4842 | |