… | |
… | |
8 | |
8 | |
9 | =head2 EXAMPLE PROGRAM |
9 | =head2 EXAMPLE PROGRAM |
10 | |
10 | |
11 | // a single header file is required |
11 | // a single header file is required |
12 | #include <ev.h> |
12 | #include <ev.h> |
|
|
13 | |
|
|
14 | #include <stdio.h> // for puts |
13 | |
15 | |
14 | // every watcher type has its own typedef'd struct |
16 | // every watcher type has its own typedef'd struct |
15 | // with the name ev_TYPE |
17 | // with the name ev_TYPE |
16 | ev_io stdin_watcher; |
18 | ev_io stdin_watcher; |
17 | ev_timer timeout_watcher; |
19 | ev_timer timeout_watcher; |
… | |
… | |
41 | |
43 | |
42 | int |
44 | int |
43 | main (void) |
45 | main (void) |
44 | { |
46 | { |
45 | // use the default event loop unless you have special needs |
47 | // use the default event loop unless you have special needs |
46 | ev_loop *loop = ev_default_loop (0); |
48 | struct ev_loop *loop = ev_default_loop (0); |
47 | |
49 | |
48 | // initialise an io watcher, then start it |
50 | // initialise an io watcher, then start it |
49 | // this one will watch for stdin to become readable |
51 | // this one will watch for stdin to become readable |
50 | ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ); |
52 | ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ); |
51 | ev_io_start (loop, &stdin_watcher); |
53 | ev_io_start (loop, &stdin_watcher); |
… | |
… | |
60 | |
62 | |
61 | // unloop was called, so exit |
63 | // unloop was called, so exit |
62 | return 0; |
64 | return 0; |
63 | } |
65 | } |
64 | |
66 | |
65 | =head1 DESCRIPTION |
67 | =head1 ABOUT THIS DOCUMENT |
|
|
68 | |
|
|
69 | This document documents the libev software package. |
66 | |
70 | |
67 | The newest version of this document is also available as an html-formatted |
71 | The newest version of this document is also available as an html-formatted |
68 | web page you might find easier to navigate when reading it for the first |
72 | web page you might find easier to navigate when reading it for the first |
69 | time: L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod>. |
73 | time: L<http://pod.tst.eu/http://cvs.schmorp.de/libev/ev.pod>. |
|
|
74 | |
|
|
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 |
|
|
77 | on event-based programming, nor will it introduce event-based programming |
|
|
78 | with libev. |
|
|
79 | |
|
|
80 | Familarity with event based programming techniques in general is assumed |
|
|
81 | throughout this document. |
|
|
82 | |
|
|
83 | =head1 ABOUT LIBEV |
70 | |
84 | |
71 | 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 |
72 | file descriptor being readable or a timeout occurring), and it will manage |
86 | file descriptor being readable or a timeout occurring), and it will manage |
73 | these event sources and provide your program with events. |
87 | these event sources and provide your program with events. |
74 | |
88 | |
… | |
… | |
84 | =head2 FEATURES |
98 | =head2 FEATURES |
85 | |
99 | |
86 | 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 |
87 | BSD-specific C<kqueue> and the Solaris-specific event port mechanisms |
101 | BSD-specific C<kqueue> and the Solaris-specific event port mechanisms |
88 | 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 |
89 | (for C<ev_stat>), relative timers (C<ev_timer>), absolute timers |
103 | (for C<ev_stat>), Linux eventfd/signalfd (for faster and cleaner |
90 | with customised rescheduling (C<ev_periodic>), synchronous signals |
104 | inter-thread wakeup (C<ev_async>)/signal handling (C<ev_signal>)) relative |
91 | (C<ev_signal>), process status change events (C<ev_child>), and event |
105 | timers (C<ev_timer>), absolute timers with customised rescheduling |
92 | watchers dealing with the event loop mechanism itself (C<ev_idle>, |
106 | (C<ev_periodic>), synchronous signals (C<ev_signal>), process status |
93 | 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 |
94 | 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 |
95 | (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>). |
96 | |
111 | |
97 | It also is quite fast (see this |
112 | It also is quite fast (see this |
98 | 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 |
99 | for example). |
114 | for example). |
100 | |
115 | |
… | |
… | |
103 | 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) |
104 | configuration will be described, which supports multiple event loops. For |
119 | configuration will be described, which supports multiple event loops. For |
105 | more info about various configuration options please have a look at |
120 | more info about various configuration options please have a look at |
106 | 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 |
107 | 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 |
108 | 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 |
109 | this argument. |
124 | this argument. |
110 | |
125 | |
111 | =head2 TIME REPRESENTATION |
126 | =head2 TIME REPRESENTATION |
112 | |
127 | |
113 | Libev represents time as a single floating point number, representing the |
128 | Libev represents time as a single floating point number, representing |
114 | (fractional) number of seconds since the (POSIX) epoch (somewhere near |
129 | the (fractional) number of seconds since the (POSIX) epoch (somewhere |
115 | the beginning of 1970, details are complicated, don't ask). This type is |
130 | near the beginning of 1970, details are complicated, don't ask). This |
116 | called C<ev_tstamp>, which is what you should use too. It usually aliases |
131 | type is called C<ev_tstamp>, which is what you should use too. It usually |
117 | to the C<double> type in C, and when you need to do any calculations on |
132 | aliases to the C<double> type in C. When you need to do any calculations |
118 | it, you should treat it as some floating point value. Unlike the name |
133 | on it, you should treat it as some floating point value. Unlike the name |
119 | component C<stamp> might indicate, it is also used for time differences |
134 | component C<stamp> might indicate, it is also used for time differences |
120 | throughout libev. |
135 | throughout libev. |
121 | |
136 | |
122 | =head1 ERROR HANDLING |
137 | =head1 ERROR HANDLING |
123 | |
138 | |
… | |
… | |
330 | useful to try out specific backends to test their performance, or to work |
345 | useful to try out specific backends to test their performance, or to work |
331 | around bugs. |
346 | around bugs. |
332 | |
347 | |
333 | =item C<EVFLAG_FORKCHECK> |
348 | =item C<EVFLAG_FORKCHECK> |
334 | |
349 | |
335 | Instead of calling C<ev_default_fork> or C<ev_loop_fork> manually after |
350 | Instead of calling C<ev_loop_fork> manually after a fork, you can also |
336 | a fork, you can also make libev check for a fork in each iteration by |
351 | make libev check for a fork in each iteration by enabling this flag. |
337 | enabling this flag. |
|
|
338 | |
352 | |
339 | This works by calling C<getpid ()> on every iteration of the loop, |
353 | This works by calling C<getpid ()> on every iteration of the loop, |
340 | and thus this might slow down your event loop if you do a lot of loop |
354 | and thus this might slow down your event loop if you do a lot of loop |
341 | iterations and little real work, but is usually not noticeable (on my |
355 | iterations and little real work, but is usually not noticeable (on my |
342 | GNU/Linux system for example, C<getpid> is actually a simple 5-insn sequence |
356 | GNU/Linux system for example, C<getpid> is actually a simple 5-insn sequence |
… | |
… | |
348 | flag. |
362 | flag. |
349 | |
363 | |
350 | This flag setting cannot be overridden or specified in the C<LIBEV_FLAGS> |
364 | This flag setting cannot be overridden or specified in the C<LIBEV_FLAGS> |
351 | environment variable. |
365 | environment variable. |
352 | |
366 | |
|
|
367 | =item C<EVFLAG_NOINOTIFY> |
|
|
368 | |
|
|
369 | When this flag is specified, then libev will not attempt to use the |
|
|
370 | I<inotify> API for it's C<ev_stat> watchers. Apart from debugging and |
|
|
371 | testing, this flag can be useful to conserve inotify file descriptors, as |
|
|
372 | otherwise each loop using C<ev_stat> watchers consumes one inotify handle. |
|
|
373 | |
|
|
374 | =item C<EVFLAG_SIGNALFD> |
|
|
375 | |
|
|
376 | When this flag is specified, then libev will attempt to use the |
|
|
377 | I<signalfd> API for it's C<ev_signal> (and C<ev_child>) watchers. This API |
|
|
378 | delivers signals synchronously, which makes it both faster and might make |
|
|
379 | it possible to get the queued signal data. It can also simplify signal |
|
|
380 | handling with threads, as long as you properly block signals in your |
|
|
381 | threads that are not interested in handling them. |
|
|
382 | |
|
|
383 | Signalfd will not be used by default as this changes your signal mask, and |
|
|
384 | there are a lot of shoddy libraries and programs (glib's threadpool for |
|
|
385 | example) that can't properly initialise their signal masks. |
|
|
386 | |
353 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
387 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
354 | |
388 | |
355 | This is your standard select(2) backend. Not I<completely> standard, as |
389 | This is your standard select(2) backend. Not I<completely> standard, as |
356 | libev tries to roll its own fd_set with no limits on the number of fds, |
390 | libev tries to roll its own fd_set with no limits on the number of fds, |
357 | but if that fails, expect a fairly low limit on the number of fds when |
391 | but if that fails, expect a fairly low limit on the number of fds when |
… | |
… | |
380 | |
414 | |
381 | This backend maps C<EV_READ> to C<POLLIN | POLLERR | POLLHUP>, and |
415 | This backend maps C<EV_READ> to C<POLLIN | POLLERR | POLLHUP>, and |
382 | C<EV_WRITE> to C<POLLOUT | POLLERR | POLLHUP>. |
416 | C<EV_WRITE> to C<POLLOUT | POLLERR | POLLHUP>. |
383 | |
417 | |
384 | =item C<EVBACKEND_EPOLL> (value 4, Linux) |
418 | =item C<EVBACKEND_EPOLL> (value 4, Linux) |
|
|
419 | |
|
|
420 | Use the linux-specific epoll(7) interface (for both pre- and post-2.6.9 |
|
|
421 | kernels). |
385 | |
422 | |
386 | For few fds, this backend is a bit little slower than poll and select, |
423 | For few fds, this backend is a bit little slower than poll and select, |
387 | but it scales phenomenally better. While poll and select usually scale |
424 | but it scales phenomenally better. While poll and select usually scale |
388 | like O(total_fds) where n is the total number of fds (or the highest fd), |
425 | like O(total_fds) where n is the total number of fds (or the highest fd), |
389 | epoll scales either O(1) or O(active_fds). |
426 | epoll scales either O(1) or O(active_fds). |
… | |
… | |
418 | starting a watcher (without re-setting it) also usually doesn't cause |
455 | starting a watcher (without re-setting it) also usually doesn't cause |
419 | extra overhead. A fork can both result in spurious notifications as well |
456 | extra overhead. A fork can both result in spurious notifications as well |
420 | as in libev having to destroy and recreate the epoll object, which can |
457 | as in libev having to destroy and recreate the epoll object, which can |
421 | take considerable time and thus should be avoided. |
458 | take considerable time and thus should be avoided. |
422 | |
459 | |
423 | All this means that, in practise, C<EVBACKEND_SELECT> is as fast or faster |
460 | All this means that, in practice, C<EVBACKEND_SELECT> can be as fast or |
424 | then epoll for maybe up to a hundred file descriptors. So sad. |
461 | faster than epoll for maybe up to a hundred file descriptors, depending on |
|
|
462 | the usage. So sad. |
425 | |
463 | |
426 | While nominally embeddable in other event loops, this feature is broken in |
464 | While nominally embeddable in other event loops, this feature is broken in |
427 | all kernel versions tested so far. |
465 | all kernel versions tested so far. |
428 | |
466 | |
429 | This backend maps C<EV_READ> and C<EV_WRITE> in the same way as |
467 | This backend maps C<EV_READ> and C<EV_WRITE> in the same way as |
… | |
… | |
457 | |
495 | |
458 | While nominally embeddable in other event loops, this doesn't work |
496 | While nominally embeddable in other event loops, this doesn't work |
459 | everywhere, so you might need to test for this. And since it is broken |
497 | everywhere, so you might need to test for this. And since it is broken |
460 | almost everywhere, you should only use it when you have a lot of sockets |
498 | almost everywhere, you should only use it when you have a lot of sockets |
461 | (for which it usually works), by embedding it into another event loop |
499 | (for which it usually works), by embedding it into another event loop |
462 | (e.g. C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>) and, did I mention it, |
500 | (e.g. C<EVBACKEND_SELECT> or C<EVBACKEND_POLL> (but C<poll> is of course |
463 | using it only for sockets. |
501 | also broken on OS X)) and, did I mention it, using it only for sockets. |
464 | |
502 | |
465 | This backend maps C<EV_READ> into an C<EVFILT_READ> kevent with |
503 | This backend maps C<EV_READ> into an C<EVFILT_READ> kevent with |
466 | C<NOTE_EOF>, and C<EV_WRITE> into an C<EVFILT_WRITE> kevent with |
504 | C<NOTE_EOF>, and C<EV_WRITE> into an C<EVFILT_WRITE> kevent with |
467 | C<NOTE_EOF>. |
505 | C<NOTE_EOF>. |
468 | |
506 | |
… | |
… | |
503 | |
541 | |
504 | It is definitely not recommended to use this flag. |
542 | It is definitely not recommended to use this flag. |
505 | |
543 | |
506 | =back |
544 | =back |
507 | |
545 | |
508 | If one or more of these are or'ed into the flags value, then only these |
546 | If one or more of the backend flags are or'ed into the flags value, |
509 | backends will be tried (in the reverse order as listed here). If none are |
547 | then only these backends will be tried (in the reverse order as listed |
510 | specified, all backends in C<ev_recommended_backends ()> will be tried. |
548 | here). If none are specified, all backends in C<ev_recommended_backends |
|
|
549 | ()> will be tried. |
511 | |
550 | |
512 | Example: This is the most typical usage. |
551 | Example: This is the most typical usage. |
513 | |
552 | |
514 | if (!ev_default_loop (0)) |
553 | if (!ev_default_loop (0)) |
515 | fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?"); |
554 | fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?"); |
… | |
… | |
527 | ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE); |
566 | ev_default_loop (ev_recommended_backends () | EVBACKEND_KQUEUE); |
528 | |
567 | |
529 | =item struct ev_loop *ev_loop_new (unsigned int flags) |
568 | =item struct ev_loop *ev_loop_new (unsigned int flags) |
530 | |
569 | |
531 | Similar to C<ev_default_loop>, but always creates a new event loop that is |
570 | Similar to C<ev_default_loop>, but always creates a new event loop that is |
532 | always distinct from the default loop. Unlike the default loop, it cannot |
571 | always distinct from the default loop. |
533 | handle signal and child watchers, and attempts to do so will be greeted by |
|
|
534 | undefined behaviour (or a failed assertion if assertions are enabled). |
|
|
535 | |
572 | |
536 | Note that this function I<is> thread-safe, and the recommended way to use |
573 | Note that this function I<is> thread-safe, and one common way to use |
537 | libev with threads is indeed to create one loop per thread, and using the |
574 | libev with threads is indeed to create one loop per thread, and using the |
538 | default loop in the "main" or "initial" thread. |
575 | default loop in the "main" or "initial" thread. |
539 | |
576 | |
540 | Example: Try to create a event loop that uses epoll and nothing else. |
577 | Example: Try to create a event loop that uses epoll and nothing else. |
541 | |
578 | |
… | |
… | |
543 | if (!epoller) |
580 | if (!epoller) |
544 | fatal ("no epoll found here, maybe it hides under your chair"); |
581 | fatal ("no epoll found here, maybe it hides under your chair"); |
545 | |
582 | |
546 | =item ev_default_destroy () |
583 | =item ev_default_destroy () |
547 | |
584 | |
548 | Destroys the default loop again (frees all memory and kernel state |
585 | Destroys the default loop (frees all memory and kernel state etc.). None |
549 | etc.). None of the active event watchers will be stopped in the normal |
586 | of the active event watchers will be stopped in the normal sense, so |
550 | sense, so e.g. C<ev_is_active> might still return true. It is your |
587 | e.g. C<ev_is_active> might still return true. It is your responsibility to |
551 | responsibility to either stop all watchers cleanly yourself I<before> |
588 | either stop all watchers cleanly yourself I<before> calling this function, |
552 | calling this function, or cope with the fact afterwards (which is usually |
589 | or cope with the fact afterwards (which is usually the easiest thing, you |
553 | the easiest thing, you can just ignore the watchers and/or C<free ()> them |
590 | can just ignore the watchers and/or C<free ()> them for example). |
554 | for example). |
|
|
555 | |
591 | |
556 | Note that certain global state, such as signal state (and installed signal |
592 | Note that certain global state, such as signal state (and installed signal |
557 | handlers), will not be freed by this function, and related watchers (such |
593 | handlers), will not be freed by this function, and related watchers (such |
558 | as signal and child watchers) would need to be stopped manually. |
594 | as signal and child watchers) would need to be stopped manually. |
559 | |
595 | |
560 | In general it is not advisable to call this function except in the |
596 | In general it is not advisable to call this function except in the |
561 | rare occasion where you really need to free e.g. the signal handling |
597 | rare occasion where you really need to free e.g. the signal handling |
562 | pipe fds. If you need dynamically allocated loops it is better to use |
598 | pipe fds. If you need dynamically allocated loops it is better to use |
563 | C<ev_loop_new> and C<ev_loop_destroy>). |
599 | C<ev_loop_new> and C<ev_loop_destroy>. |
564 | |
600 | |
565 | =item ev_loop_destroy (loop) |
601 | =item ev_loop_destroy (loop) |
566 | |
602 | |
567 | Like C<ev_default_destroy>, but destroys an event loop created by an |
603 | Like C<ev_default_destroy>, but destroys an event loop created by an |
568 | earlier call to C<ev_loop_new>. |
604 | earlier call to C<ev_loop_new>. |
… | |
… | |
574 | name, you can call it anytime, but it makes most sense after forking, in |
610 | name, you can call it anytime, but it makes most sense after forking, in |
575 | the child process (or both child and parent, but that again makes little |
611 | the child process (or both child and parent, but that again makes little |
576 | sense). You I<must> call it in the child before using any of the libev |
612 | sense). You I<must> call it in the child before using any of the libev |
577 | functions, and it will only take effect at the next C<ev_loop> iteration. |
613 | functions, and it will only take effect at the next C<ev_loop> iteration. |
578 | |
614 | |
|
|
615 | Again, you I<have> to call it on I<any> loop that you want to re-use after |
|
|
616 | a fork, I<even if you do not plan to use the loop in the parent>. This is |
|
|
617 | because some kernel interfaces *cough* I<kqueue> *cough* do funny things |
|
|
618 | during fork. |
|
|
619 | |
579 | On the other hand, you only need to call this function in the child |
620 | On the other hand, you only need to call this function in the child |
580 | process if and only if you want to use the event library in the child. If |
621 | process if and only if you want to use the event loop in the child. If you |
581 | you just fork+exec, you don't have to call it at all. |
622 | just fork+exec or create a new loop in the child, you don't have to call |
|
|
623 | it at all. |
582 | |
624 | |
583 | The function itself is quite fast and it's usually not a problem to call |
625 | The function itself is quite fast and it's usually not a problem to call |
584 | it just in case after a fork. To make this easy, the function will fit in |
626 | it just in case after a fork. To make this easy, the function will fit in |
585 | quite nicely into a call to C<pthread_atfork>: |
627 | quite nicely into a call to C<pthread_atfork>: |
586 | |
628 | |
… | |
… | |
588 | |
630 | |
589 | =item ev_loop_fork (loop) |
631 | =item ev_loop_fork (loop) |
590 | |
632 | |
591 | Like C<ev_default_fork>, but acts on an event loop created by |
633 | Like C<ev_default_fork>, but acts on an event loop created by |
592 | C<ev_loop_new>. Yes, you have to call this on every allocated event loop |
634 | C<ev_loop_new>. Yes, you have to call this on every allocated event loop |
593 | after fork that you want to re-use in the child, and how you do this is |
635 | after fork that you want to re-use in the child, and how you keep track of |
594 | entirely your own problem. |
636 | them is entirely your own problem. |
595 | |
637 | |
596 | =item int ev_is_default_loop (loop) |
638 | =item int ev_is_default_loop (loop) |
597 | |
639 | |
598 | Returns true when the given loop is, in fact, the default loop, and false |
640 | Returns true when the given loop is, in fact, the default loop, and false |
599 | otherwise. |
641 | otherwise. |
600 | |
642 | |
601 | =item unsigned int ev_loop_count (loop) |
643 | =item unsigned int ev_iteration (loop) |
602 | |
644 | |
603 | Returns the count of loop iterations for the loop, which is identical to |
645 | Returns the current iteration count for the loop, which is identical to |
604 | the number of times libev did poll for new events. It starts at C<0> and |
646 | the number of times libev did poll for new events. It starts at C<0> and |
605 | happily wraps around with enough iterations. |
647 | happily wraps around with enough iterations. |
606 | |
648 | |
607 | This value can sometimes be useful as a generation counter of sorts (it |
649 | This value can sometimes be useful as a generation counter of sorts (it |
608 | "ticks" the number of loop iterations), as it roughly corresponds with |
650 | "ticks" the number of loop iterations), as it roughly corresponds with |
609 | C<ev_prepare> and C<ev_check> calls. |
651 | C<ev_prepare> and C<ev_check> calls - and is incremented between the |
|
|
652 | prepare and check phases. |
|
|
653 | |
|
|
654 | =item unsigned int ev_depth (loop) |
|
|
655 | |
|
|
656 | Returns the number of times C<ev_loop> was entered minus the number of |
|
|
657 | times C<ev_loop> was exited, in other words, the recursion depth. |
|
|
658 | |
|
|
659 | Outside C<ev_loop>, this number is zero. In a callback, this number is |
|
|
660 | C<1>, unless C<ev_loop> was invoked recursively (or from another thread), |
|
|
661 | in which case it is higher. |
|
|
662 | |
|
|
663 | Leaving C<ev_loop> abnormally (setjmp/longjmp, cancelling the thread |
|
|
664 | etc.), doesn't count as "exit" - consider this as a hint to avoid such |
|
|
665 | ungentleman behaviour unless it's really convenient. |
610 | |
666 | |
611 | =item unsigned int ev_backend (loop) |
667 | =item unsigned int ev_backend (loop) |
612 | |
668 | |
613 | Returns one of the C<EVBACKEND_*> flags indicating the event backend in |
669 | Returns one of the C<EVBACKEND_*> flags indicating the event backend in |
614 | use. |
670 | use. |
… | |
… | |
629 | |
685 | |
630 | This function is rarely useful, but when some event callback runs for a |
686 | This function is rarely useful, but when some event callback runs for a |
631 | very long time without entering the event loop, updating libev's idea of |
687 | very long time without entering the event loop, updating libev's idea of |
632 | the current time is a good idea. |
688 | the current time is a good idea. |
633 | |
689 | |
634 | See also "The special problem of time updates" in the C<ev_timer> section. |
690 | See also L<The special problem of time updates> in the C<ev_timer> section. |
|
|
691 | |
|
|
692 | =item ev_suspend (loop) |
|
|
693 | |
|
|
694 | =item ev_resume (loop) |
|
|
695 | |
|
|
696 | These two functions suspend and resume a loop, for use when the loop is |
|
|
697 | not used for a while and timeouts should not be processed. |
|
|
698 | |
|
|
699 | A typical use case would be an interactive program such as a game: When |
|
|
700 | the user presses C<^Z> to suspend the game and resumes it an hour later it |
|
|
701 | would be best to handle timeouts as if no time had actually passed while |
|
|
702 | the program was suspended. This can be achieved by calling C<ev_suspend> |
|
|
703 | in your C<SIGTSTP> handler, sending yourself a C<SIGSTOP> and calling |
|
|
704 | C<ev_resume> directly afterwards to resume timer processing. |
|
|
705 | |
|
|
706 | Effectively, all C<ev_timer> watchers will be delayed by the time spend |
|
|
707 | between C<ev_suspend> and C<ev_resume>, and all C<ev_periodic> watchers |
|
|
708 | will be rescheduled (that is, they will lose any events that would have |
|
|
709 | occured while suspended). |
|
|
710 | |
|
|
711 | After calling C<ev_suspend> you B<must not> call I<any> function on the |
|
|
712 | given loop other than C<ev_resume>, and you B<must not> call C<ev_resume> |
|
|
713 | without a previous call to C<ev_suspend>. |
|
|
714 | |
|
|
715 | Calling C<ev_suspend>/C<ev_resume> has the side effect of updating the |
|
|
716 | event loop time (see C<ev_now_update>). |
635 | |
717 | |
636 | =item ev_loop (loop, int flags) |
718 | =item ev_loop (loop, int flags) |
637 | |
719 | |
638 | Finally, this is it, the event handler. This function usually is called |
720 | Finally, this is it, the event handler. This function usually is called |
639 | after you initialised all your watchers and you want to start handling |
721 | after you have initialised all your watchers and you want to start |
640 | events. |
722 | handling events. |
641 | |
723 | |
642 | If the flags argument is specified as C<0>, it will not return until |
724 | If the flags argument is specified as C<0>, it will not return until |
643 | either no event watchers are active anymore or C<ev_unloop> was called. |
725 | either no event watchers are active anymore or C<ev_unloop> was called. |
644 | |
726 | |
645 | Please note that an explicit C<ev_unloop> is usually better than |
727 | Please note that an explicit C<ev_unloop> is usually better than |
… | |
… | |
719 | |
801 | |
720 | Ref/unref can be used to add or remove a reference count on the event |
802 | Ref/unref can be used to add or remove a reference count on the event |
721 | loop: Every watcher keeps one reference, and as long as the reference |
803 | loop: Every watcher keeps one reference, and as long as the reference |
722 | count is nonzero, C<ev_loop> will not return on its own. |
804 | count is nonzero, C<ev_loop> will not return on its own. |
723 | |
805 | |
724 | If you have a watcher you never unregister that should not keep C<ev_loop> |
806 | This is useful when you have a watcher that you never intend to |
725 | from returning, call ev_unref() after starting, and ev_ref() before |
807 | unregister, but that nevertheless should not keep C<ev_loop> from |
|
|
808 | returning. In such a case, call C<ev_unref> after starting, and C<ev_ref> |
726 | stopping it. |
809 | before stopping it. |
727 | |
810 | |
728 | As an example, libev itself uses this for its internal signal pipe: It is |
811 | As an example, libev itself uses this for its internal signal pipe: It |
729 | not visible to the libev user and should not keep C<ev_loop> from exiting |
812 | is not visible to the libev user and should not keep C<ev_loop> from |
730 | if no event watchers registered by it are active. It is also an excellent |
813 | exiting if no event watchers registered by it are active. It is also an |
731 | way to do this for generic recurring timers or from within third-party |
814 | excellent way to do this for generic recurring timers or from within |
732 | libraries. Just remember to I<unref after start> and I<ref before stop> |
815 | third-party libraries. Just remember to I<unref after start> and I<ref |
733 | (but only if the watcher wasn't active before, or was active before, |
816 | before stop> (but only if the watcher wasn't active before, or was active |
734 | respectively). |
817 | before, respectively. Note also that libev might stop watchers itself |
|
|
818 | (e.g. non-repeating timers) in which case you have to C<ev_ref> |
|
|
819 | in the callback). |
735 | |
820 | |
736 | Example: Create a signal watcher, but keep it from keeping C<ev_loop> |
821 | Example: Create a signal watcher, but keep it from keeping C<ev_loop> |
737 | running when nothing else is active. |
822 | running when nothing else is active. |
738 | |
823 | |
739 | ev_signal exitsig; |
824 | ev_signal exitsig; |
… | |
… | |
768 | |
853 | |
769 | By setting a higher I<io collect interval> you allow libev to spend more |
854 | By setting a higher I<io collect interval> you allow libev to spend more |
770 | time collecting I/O events, so you can handle more events per iteration, |
855 | time collecting I/O events, so you can handle more events per iteration, |
771 | at the cost of increasing latency. Timeouts (both C<ev_periodic> and |
856 | at the cost of increasing latency. Timeouts (both C<ev_periodic> and |
772 | C<ev_timer>) will be not affected. Setting this to a non-null value will |
857 | C<ev_timer>) will be not affected. Setting this to a non-null value will |
773 | introduce an additional C<ev_sleep ()> call into most loop iterations. |
858 | introduce an additional C<ev_sleep ()> call into most loop iterations. The |
|
|
859 | sleep time ensures that libev will not poll for I/O events more often then |
|
|
860 | once per this interval, on average. |
774 | |
861 | |
775 | Likewise, by setting a higher I<timeout collect interval> you allow libev |
862 | Likewise, by setting a higher I<timeout collect interval> you allow libev |
776 | to spend more time collecting timeouts, at the expense of increased |
863 | to spend more time collecting timeouts, at the expense of increased |
777 | latency/jitter/inexactness (the watcher callback will be called |
864 | latency/jitter/inexactness (the watcher callback will be called |
778 | later). C<ev_io> watchers will not be affected. Setting this to a non-null |
865 | later). C<ev_io> watchers will not be affected. Setting this to a non-null |
… | |
… | |
780 | |
867 | |
781 | Many (busy) programs can usually benefit by setting the I/O collect |
868 | Many (busy) programs can usually benefit by setting the I/O collect |
782 | interval to a value near C<0.1> or so, which is often enough for |
869 | interval to a value near C<0.1> or so, which is often enough for |
783 | interactive servers (of course not for games), likewise for timeouts. It |
870 | interactive servers (of course not for games), likewise for timeouts. It |
784 | usually doesn't make much sense to set it to a lower value than C<0.01>, |
871 | usually doesn't make much sense to set it to a lower value than C<0.01>, |
785 | as this approaches the timing granularity of most systems. |
872 | as this approaches the timing granularity of most systems. Note that if |
|
|
873 | you do transactions with the outside world and you can't increase the |
|
|
874 | parallelity, then this setting will limit your transaction rate (if you |
|
|
875 | need to poll once per transaction and the I/O collect interval is 0.01, |
|
|
876 | then you can't do more than 100 transations per second). |
786 | |
877 | |
787 | Setting the I<timeout collect interval> can improve the opportunity for |
878 | Setting the I<timeout collect interval> can improve the opportunity for |
788 | saving power, as the program will "bundle" timer callback invocations that |
879 | saving power, as the program will "bundle" timer callback invocations that |
789 | are "near" in time together, by delaying some, thus reducing the number of |
880 | are "near" in time together, by delaying some, thus reducing the number of |
790 | times the process sleeps and wakes up again. Another useful technique to |
881 | times the process sleeps and wakes up again. Another useful technique to |
791 | reduce iterations/wake-ups is to use C<ev_periodic> watchers and make sure |
882 | reduce iterations/wake-ups is to use C<ev_periodic> watchers and make sure |
792 | they fire on, say, one-second boundaries only. |
883 | they fire on, say, one-second boundaries only. |
793 | |
884 | |
|
|
885 | Example: we only need 0.1s timeout granularity, and we wish not to poll |
|
|
886 | more often than 100 times per second: |
|
|
887 | |
|
|
888 | ev_set_timeout_collect_interval (EV_DEFAULT_UC_ 0.1); |
|
|
889 | ev_set_io_collect_interval (EV_DEFAULT_UC_ 0.01); |
|
|
890 | |
|
|
891 | =item ev_invoke_pending (loop) |
|
|
892 | |
|
|
893 | This call will simply invoke all pending watchers while resetting their |
|
|
894 | pending state. Normally, C<ev_loop> does this automatically when required, |
|
|
895 | but when overriding the invoke callback this call comes handy. |
|
|
896 | |
|
|
897 | =item int ev_pending_count (loop) |
|
|
898 | |
|
|
899 | Returns the number of pending watchers - zero indicates that no watchers |
|
|
900 | are pending. |
|
|
901 | |
|
|
902 | =item ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(EV_P)) |
|
|
903 | |
|
|
904 | This overrides the invoke pending functionality of the loop: Instead of |
|
|
905 | invoking all pending watchers when there are any, C<ev_loop> will call |
|
|
906 | this callback instead. This is useful, for example, when you want to |
|
|
907 | invoke the actual watchers inside another context (another thread etc.). |
|
|
908 | |
|
|
909 | If you want to reset the callback, use C<ev_invoke_pending> as new |
|
|
910 | callback. |
|
|
911 | |
|
|
912 | =item ev_set_loop_release_cb (loop, void (*release)(EV_P), void (*acquire)(EV_P)) |
|
|
913 | |
|
|
914 | Sometimes you want to share the same loop between multiple threads. This |
|
|
915 | can be done relatively simply by putting mutex_lock/unlock calls around |
|
|
916 | each call to a libev function. |
|
|
917 | |
|
|
918 | However, C<ev_loop> can run an indefinite time, so it is not feasible to |
|
|
919 | wait for it to return. One way around this is to wake up the loop via |
|
|
920 | C<ev_unloop> and C<av_async_send>, another way is to set these I<release> |
|
|
921 | and I<acquire> callbacks on the loop. |
|
|
922 | |
|
|
923 | When set, then C<release> will be called just before the thread is |
|
|
924 | suspended waiting for new events, and C<acquire> is called just |
|
|
925 | afterwards. |
|
|
926 | |
|
|
927 | Ideally, C<release> will just call your mutex_unlock function, and |
|
|
928 | C<acquire> will just call the mutex_lock function again. |
|
|
929 | |
|
|
930 | While event loop modifications are allowed between invocations of |
|
|
931 | C<release> and C<acquire> (that's their only purpose after all), no |
|
|
932 | modifications done will affect the event loop, i.e. adding watchers will |
|
|
933 | have no effect on the set of file descriptors being watched, or the time |
|
|
934 | waited. Use an C<ev_async> watcher to wake up C<ev_loop> when you want it |
|
|
935 | to take note of any changes you made. |
|
|
936 | |
|
|
937 | In theory, threads executing C<ev_loop> will be async-cancel safe between |
|
|
938 | invocations of C<release> and C<acquire>. |
|
|
939 | |
|
|
940 | See also the locking example in the C<THREADS> section later in this |
|
|
941 | document. |
|
|
942 | |
|
|
943 | =item ev_set_userdata (loop, void *data) |
|
|
944 | |
|
|
945 | =item ev_userdata (loop) |
|
|
946 | |
|
|
947 | Set and retrieve a single C<void *> associated with a loop. When |
|
|
948 | C<ev_set_userdata> has never been called, then C<ev_userdata> returns |
|
|
949 | C<0.> |
|
|
950 | |
|
|
951 | These two functions can be used to associate arbitrary data with a loop, |
|
|
952 | and are intended solely for the C<invoke_pending_cb>, C<release> and |
|
|
953 | C<acquire> callbacks described above, but of course can be (ab-)used for |
|
|
954 | any other purpose as well. |
|
|
955 | |
794 | =item ev_loop_verify (loop) |
956 | =item ev_loop_verify (loop) |
795 | |
957 | |
796 | This function only does something when C<EV_VERIFY> support has been |
958 | This function only does something when C<EV_VERIFY> support has been |
797 | compiled in, which is the default for non-minimal builds. It tries to go |
959 | compiled in, which is the default for non-minimal builds. It tries to go |
798 | through all internal structures and checks them for validity. If anything |
960 | through all internal structures and checks them for validity. If anything |
… | |
… | |
874 | =item C<EV_WRITE> |
1036 | =item C<EV_WRITE> |
875 | |
1037 | |
876 | The file descriptor in the C<ev_io> watcher has become readable and/or |
1038 | The file descriptor in the C<ev_io> watcher has become readable and/or |
877 | writable. |
1039 | writable. |
878 | |
1040 | |
879 | =item C<EV_TIMEOUT> |
1041 | =item C<EV_TIMER> |
880 | |
1042 | |
881 | The C<ev_timer> watcher has timed out. |
1043 | The C<ev_timer> watcher has timed out. |
882 | |
1044 | |
883 | =item C<EV_PERIODIC> |
1045 | =item C<EV_PERIODIC> |
884 | |
1046 | |
… | |
… | |
923 | |
1085 | |
924 | =item C<EV_ASYNC> |
1086 | =item C<EV_ASYNC> |
925 | |
1087 | |
926 | The given async watcher has been asynchronously notified (see C<ev_async>). |
1088 | The given async watcher has been asynchronously notified (see C<ev_async>). |
927 | |
1089 | |
|
|
1090 | =item C<EV_CUSTOM> |
|
|
1091 | |
|
|
1092 | Not ever sent (or otherwise used) by libev itself, but can be freely used |
|
|
1093 | by libev users to signal watchers (e.g. via C<ev_feed_event>). |
|
|
1094 | |
928 | =item C<EV_ERROR> |
1095 | =item C<EV_ERROR> |
929 | |
1096 | |
930 | An unspecified error has occurred, the watcher has been stopped. This might |
1097 | An unspecified error has occurred, the watcher has been stopped. This might |
931 | happen because the watcher could not be properly started because libev |
1098 | happen because the watcher could not be properly started because libev |
932 | ran out of memory, a file descriptor was found to be closed or any other |
1099 | ran out of memory, a file descriptor was found to be closed or any other |
… | |
… | |
969 | |
1136 | |
970 | ev_io w; |
1137 | ev_io w; |
971 | ev_init (&w, my_cb); |
1138 | ev_init (&w, my_cb); |
972 | ev_io_set (&w, STDIN_FILENO, EV_READ); |
1139 | ev_io_set (&w, STDIN_FILENO, EV_READ); |
973 | |
1140 | |
974 | =item C<ev_TYPE_set> (ev_TYPE *, [args]) |
1141 | =item C<ev_TYPE_set> (ev_TYPE *watcher, [args]) |
975 | |
1142 | |
976 | This macro initialises the type-specific parts of a watcher. You need to |
1143 | This macro initialises the type-specific parts of a watcher. You need to |
977 | call C<ev_init> at least once before you call this macro, but you can |
1144 | call C<ev_init> at least once before you call this macro, but you can |
978 | call C<ev_TYPE_set> any number of times. You must not, however, call this |
1145 | call C<ev_TYPE_set> any number of times. You must not, however, call this |
979 | macro on a watcher that is active (it can be pending, however, which is a |
1146 | macro on a watcher that is active (it can be pending, however, which is a |
… | |
… | |
992 | |
1159 | |
993 | Example: Initialise and set an C<ev_io> watcher in one step. |
1160 | Example: Initialise and set an C<ev_io> watcher in one step. |
994 | |
1161 | |
995 | ev_io_init (&w, my_cb, STDIN_FILENO, EV_READ); |
1162 | ev_io_init (&w, my_cb, STDIN_FILENO, EV_READ); |
996 | |
1163 | |
997 | =item C<ev_TYPE_start> (loop *, ev_TYPE *watcher) |
1164 | =item C<ev_TYPE_start> (loop, ev_TYPE *watcher) |
998 | |
1165 | |
999 | Starts (activates) the given watcher. Only active watchers will receive |
1166 | Starts (activates) the given watcher. Only active watchers will receive |
1000 | events. If the watcher is already active nothing will happen. |
1167 | events. If the watcher is already active nothing will happen. |
1001 | |
1168 | |
1002 | Example: Start the C<ev_io> watcher that is being abused as example in this |
1169 | Example: Start the C<ev_io> watcher that is being abused as example in this |
1003 | whole section. |
1170 | whole section. |
1004 | |
1171 | |
1005 | ev_io_start (EV_DEFAULT_UC, &w); |
1172 | ev_io_start (EV_DEFAULT_UC, &w); |
1006 | |
1173 | |
1007 | =item C<ev_TYPE_stop> (loop *, ev_TYPE *watcher) |
1174 | =item C<ev_TYPE_stop> (loop, ev_TYPE *watcher) |
1008 | |
1175 | |
1009 | Stops the given watcher if active, and clears the pending status (whether |
1176 | Stops the given watcher if active, and clears the pending status (whether |
1010 | the watcher was active or not). |
1177 | the watcher was active or not). |
1011 | |
1178 | |
1012 | It is possible that stopped watchers are pending - for example, |
1179 | It is possible that stopped watchers are pending - for example, |
… | |
… | |
1037 | =item ev_cb_set (ev_TYPE *watcher, callback) |
1204 | =item ev_cb_set (ev_TYPE *watcher, callback) |
1038 | |
1205 | |
1039 | Change the callback. You can change the callback at virtually any time |
1206 | Change the callback. You can change the callback at virtually any time |
1040 | (modulo threads). |
1207 | (modulo threads). |
1041 | |
1208 | |
1042 | =item ev_set_priority (ev_TYPE *watcher, priority) |
1209 | =item ev_set_priority (ev_TYPE *watcher, int priority) |
1043 | |
1210 | |
1044 | =item int ev_priority (ev_TYPE *watcher) |
1211 | =item int ev_priority (ev_TYPE *watcher) |
1045 | |
1212 | |
1046 | Set and query the priority of the watcher. The priority is a small |
1213 | Set and query the priority of the watcher. The priority is a small |
1047 | integer between C<EV_MAXPRI> (default: C<2>) and C<EV_MINPRI> |
1214 | integer between C<EV_MAXPRI> (default: C<2>) and C<EV_MINPRI> |
1048 | (default: C<-2>). Pending watchers with higher priority will be invoked |
1215 | (default: C<-2>). Pending watchers with higher priority will be invoked |
1049 | before watchers with lower priority, but priority will not keep watchers |
1216 | before watchers with lower priority, but priority will not keep watchers |
1050 | from being executed (except for C<ev_idle> watchers). |
1217 | from being executed (except for C<ev_idle> watchers). |
1051 | |
1218 | |
1052 | This means that priorities are I<only> used for ordering callback |
|
|
1053 | invocation after new events have been received. This is useful, for |
|
|
1054 | example, to reduce latency after idling, or more often, to bind two |
|
|
1055 | watchers on the same event and make sure one is called first. |
|
|
1056 | |
|
|
1057 | If you need to suppress invocation when higher priority events are pending |
1219 | If you need to suppress invocation when higher priority events are pending |
1058 | you need to look at C<ev_idle> watchers, which provide this functionality. |
1220 | you need to look at C<ev_idle> watchers, which provide this functionality. |
1059 | |
1221 | |
1060 | You I<must not> change the priority of a watcher as long as it is active or |
1222 | You I<must not> change the priority of a watcher as long as it is active or |
1061 | pending. |
1223 | pending. |
1062 | |
|
|
1063 | The default priority used by watchers when no priority has been set is |
|
|
1064 | always C<0>, which is supposed to not be too high and not be too low :). |
|
|
1065 | |
1224 | |
1066 | Setting a priority outside the range of C<EV_MINPRI> to C<EV_MAXPRI> is |
1225 | Setting a priority outside the range of C<EV_MINPRI> to C<EV_MAXPRI> is |
1067 | fine, as long as you do not mind that the priority value you query might |
1226 | fine, as long as you do not mind that the priority value you query might |
1068 | or might not have been clamped to the valid range. |
1227 | or might not have been clamped to the valid range. |
|
|
1228 | |
|
|
1229 | The default priority used by watchers when no priority has been set is |
|
|
1230 | always C<0>, which is supposed to not be too high and not be too low :). |
|
|
1231 | |
|
|
1232 | See L<WATCHER PRIORITY MODELS>, below, for a more thorough treatment of |
|
|
1233 | priorities. |
1069 | |
1234 | |
1070 | =item ev_invoke (loop, ev_TYPE *watcher, int revents) |
1235 | =item ev_invoke (loop, ev_TYPE *watcher, int revents) |
1071 | |
1236 | |
1072 | Invoke the C<watcher> with the given C<loop> and C<revents>. Neither |
1237 | Invoke the C<watcher> with the given C<loop> and C<revents>. Neither |
1073 | C<loop> nor C<revents> need to be valid as long as the watcher callback |
1238 | C<loop> nor C<revents> need to be valid as long as the watcher callback |
… | |
… | |
1080 | returns its C<revents> bitset (as if its callback was invoked). If the |
1245 | returns its C<revents> bitset (as if its callback was invoked). If the |
1081 | watcher isn't pending it does nothing and returns C<0>. |
1246 | watcher isn't pending it does nothing and returns C<0>. |
1082 | |
1247 | |
1083 | Sometimes it can be useful to "poll" a watcher instead of waiting for its |
1248 | Sometimes it can be useful to "poll" a watcher instead of waiting for its |
1084 | callback to be invoked, which can be accomplished with this function. |
1249 | callback to be invoked, which can be accomplished with this function. |
|
|
1250 | |
|
|
1251 | =item ev_feed_event (loop, ev_TYPE *watcher, int revents) |
|
|
1252 | |
|
|
1253 | Feeds the given event set into the event loop, as if the specified event |
|
|
1254 | had happened for the specified watcher (which must be a pointer to an |
|
|
1255 | initialised but not necessarily started event watcher). Obviously you must |
|
|
1256 | not free the watcher as long as it has pending events. |
|
|
1257 | |
|
|
1258 | Stopping the watcher, letting libev invoke it, or calling |
|
|
1259 | C<ev_clear_pending> will clear the pending event, even if the watcher was |
|
|
1260 | not started in the first place. |
|
|
1261 | |
|
|
1262 | See also C<ev_feed_fd_event> and C<ev_feed_signal_event> for related |
|
|
1263 | functions that do not need a watcher. |
1085 | |
1264 | |
1086 | =back |
1265 | =back |
1087 | |
1266 | |
1088 | |
1267 | |
1089 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
1268 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
… | |
… | |
1138 | #include <stddef.h> |
1317 | #include <stddef.h> |
1139 | |
1318 | |
1140 | static void |
1319 | static void |
1141 | t1_cb (EV_P_ ev_timer *w, int revents) |
1320 | t1_cb (EV_P_ ev_timer *w, int revents) |
1142 | { |
1321 | { |
1143 | struct my_biggy big = (struct my_biggy * |
1322 | struct my_biggy big = (struct my_biggy *) |
1144 | (((char *)w) - offsetof (struct my_biggy, t1)); |
1323 | (((char *)w) - offsetof (struct my_biggy, t1)); |
1145 | } |
1324 | } |
1146 | |
1325 | |
1147 | static void |
1326 | static void |
1148 | t2_cb (EV_P_ ev_timer *w, int revents) |
1327 | t2_cb (EV_P_ ev_timer *w, int revents) |
1149 | { |
1328 | { |
1150 | struct my_biggy big = (struct my_biggy * |
1329 | struct my_biggy big = (struct my_biggy *) |
1151 | (((char *)w) - offsetof (struct my_biggy, t2)); |
1330 | (((char *)w) - offsetof (struct my_biggy, t2)); |
1152 | } |
1331 | } |
|
|
1332 | |
|
|
1333 | =head2 WATCHER PRIORITY MODELS |
|
|
1334 | |
|
|
1335 | Many event loops support I<watcher priorities>, which are usually small |
|
|
1336 | integers that influence the ordering of event callback invocation |
|
|
1337 | between watchers in some way, all else being equal. |
|
|
1338 | |
|
|
1339 | In libev, Watcher priorities can be set using C<ev_set_priority>. See its |
|
|
1340 | description for the more technical details such as the actual priority |
|
|
1341 | range. |
|
|
1342 | |
|
|
1343 | There are two common ways how these these priorities are being interpreted |
|
|
1344 | by event loops: |
|
|
1345 | |
|
|
1346 | In the more common lock-out model, higher priorities "lock out" invocation |
|
|
1347 | of lower priority watchers, which means as long as higher priority |
|
|
1348 | watchers receive events, lower priority watchers are not being invoked. |
|
|
1349 | |
|
|
1350 | The less common only-for-ordering model uses priorities solely to order |
|
|
1351 | callback invocation within a single event loop iteration: Higher priority |
|
|
1352 | watchers are invoked before lower priority ones, but they all get invoked |
|
|
1353 | before polling for new events. |
|
|
1354 | |
|
|
1355 | Libev uses the second (only-for-ordering) model for all its watchers |
|
|
1356 | except for idle watchers (which use the lock-out model). |
|
|
1357 | |
|
|
1358 | The rationale behind this is that implementing the lock-out model for |
|
|
1359 | watchers is not well supported by most kernel interfaces, and most event |
|
|
1360 | libraries will just poll for the same events again and again as long as |
|
|
1361 | their callbacks have not been executed, which is very inefficient in the |
|
|
1362 | common case of one high-priority watcher locking out a mass of lower |
|
|
1363 | priority ones. |
|
|
1364 | |
|
|
1365 | Static (ordering) priorities are most useful when you have two or more |
|
|
1366 | watchers handling the same resource: a typical usage example is having an |
|
|
1367 | C<ev_io> watcher to receive data, and an associated C<ev_timer> to handle |
|
|
1368 | timeouts. Under load, data might be received while the program handles |
|
|
1369 | other jobs, but since timers normally get invoked first, the timeout |
|
|
1370 | handler will be executed before checking for data. In that case, giving |
|
|
1371 | the timer a lower priority than the I/O watcher ensures that I/O will be |
|
|
1372 | handled first even under adverse conditions (which is usually, but not |
|
|
1373 | always, what you want). |
|
|
1374 | |
|
|
1375 | Since idle watchers use the "lock-out" model, meaning that idle watchers |
|
|
1376 | will only be executed when no same or higher priority watchers have |
|
|
1377 | received events, they can be used to implement the "lock-out" model when |
|
|
1378 | required. |
|
|
1379 | |
|
|
1380 | For example, to emulate how many other event libraries handle priorities, |
|
|
1381 | you can associate an C<ev_idle> watcher to each such watcher, and in |
|
|
1382 | the normal watcher callback, you just start the idle watcher. The real |
|
|
1383 | processing is done in the idle watcher callback. This causes libev to |
|
|
1384 | continously poll and process kernel event data for the watcher, but when |
|
|
1385 | the lock-out case is known to be rare (which in turn is rare :), this is |
|
|
1386 | workable. |
|
|
1387 | |
|
|
1388 | Usually, however, the lock-out model implemented that way will perform |
|
|
1389 | miserably under the type of load it was designed to handle. In that case, |
|
|
1390 | it might be preferable to stop the real watcher before starting the |
|
|
1391 | idle watcher, so the kernel will not have to process the event in case |
|
|
1392 | the actual processing will be delayed for considerable time. |
|
|
1393 | |
|
|
1394 | Here is an example of an I/O watcher that should run at a strictly lower |
|
|
1395 | priority than the default, and which should only process data when no |
|
|
1396 | other events are pending: |
|
|
1397 | |
|
|
1398 | ev_idle idle; // actual processing watcher |
|
|
1399 | ev_io io; // actual event watcher |
|
|
1400 | |
|
|
1401 | static void |
|
|
1402 | io_cb (EV_P_ ev_io *w, int revents) |
|
|
1403 | { |
|
|
1404 | // stop the I/O watcher, we received the event, but |
|
|
1405 | // are not yet ready to handle it. |
|
|
1406 | ev_io_stop (EV_A_ w); |
|
|
1407 | |
|
|
1408 | // start the idle watcher to ahndle the actual event. |
|
|
1409 | // it will not be executed as long as other watchers |
|
|
1410 | // with the default priority are receiving events. |
|
|
1411 | ev_idle_start (EV_A_ &idle); |
|
|
1412 | } |
|
|
1413 | |
|
|
1414 | static void |
|
|
1415 | idle_cb (EV_P_ ev_idle *w, int revents) |
|
|
1416 | { |
|
|
1417 | // actual processing |
|
|
1418 | read (STDIN_FILENO, ...); |
|
|
1419 | |
|
|
1420 | // have to start the I/O watcher again, as |
|
|
1421 | // we have handled the event |
|
|
1422 | ev_io_start (EV_P_ &io); |
|
|
1423 | } |
|
|
1424 | |
|
|
1425 | // initialisation |
|
|
1426 | ev_idle_init (&idle, idle_cb); |
|
|
1427 | ev_io_init (&io, io_cb, STDIN_FILENO, EV_READ); |
|
|
1428 | ev_io_start (EV_DEFAULT_ &io); |
|
|
1429 | |
|
|
1430 | In the "real" world, it might also be beneficial to start a timer, so that |
|
|
1431 | low-priority connections can not be locked out forever under load. This |
|
|
1432 | enables your program to keep a lower latency for important connections |
|
|
1433 | during short periods of high load, while not completely locking out less |
|
|
1434 | important ones. |
1153 | |
1435 | |
1154 | |
1436 | |
1155 | =head1 WATCHER TYPES |
1437 | =head1 WATCHER TYPES |
1156 | |
1438 | |
1157 | This section describes each watcher in detail, but will not repeat |
1439 | This section describes each watcher in detail, but will not repeat |
… | |
… | |
1183 | descriptors to non-blocking mode is also usually a good idea (but not |
1465 | descriptors to non-blocking mode is also usually a good idea (but not |
1184 | required if you know what you are doing). |
1466 | required if you know what you are doing). |
1185 | |
1467 | |
1186 | If you cannot use non-blocking mode, then force the use of a |
1468 | If you cannot use non-blocking mode, then force the use of a |
1187 | known-to-be-good backend (at the time of this writing, this includes only |
1469 | known-to-be-good backend (at the time of this writing, this includes only |
1188 | C<EVBACKEND_SELECT> and C<EVBACKEND_POLL>). |
1470 | C<EVBACKEND_SELECT> and C<EVBACKEND_POLL>). The same applies to file |
|
|
1471 | descriptors for which non-blocking operation makes no sense (such as |
|
|
1472 | files) - libev doesn't guarentee any specific behaviour in that case. |
1189 | |
1473 | |
1190 | Another thing you have to watch out for is that it is quite easy to |
1474 | Another thing you have to watch out for is that it is quite easy to |
1191 | receive "spurious" readiness notifications, that is your callback might |
1475 | receive "spurious" readiness notifications, that is your callback might |
1192 | be called with C<EV_READ> but a subsequent C<read>(2) will actually block |
1476 | be called with C<EV_READ> but a subsequent C<read>(2) will actually block |
1193 | because there is no data. Not only are some backends known to create a |
1477 | because there is no data. Not only are some backends known to create a |
… | |
… | |
1258 | |
1542 | |
1259 | So when you encounter spurious, unexplained daemon exits, make sure you |
1543 | So when you encounter spurious, unexplained daemon exits, make sure you |
1260 | ignore SIGPIPE (and maybe make sure you log the exit status of your daemon |
1544 | ignore SIGPIPE (and maybe make sure you log the exit status of your daemon |
1261 | somewhere, as that would have given you a big clue). |
1545 | somewhere, as that would have given you a big clue). |
1262 | |
1546 | |
|
|
1547 | =head3 The special problem of accept()ing when you can't |
|
|
1548 | |
|
|
1549 | Many implementations of the POSIX C<accept> function (for example, |
|
|
1550 | found in post-2004 Linux) have the peculiar behaviour of not removing a |
|
|
1551 | connection from the pending queue in all error cases. |
|
|
1552 | |
|
|
1553 | For example, larger servers often run out of file descriptors (because |
|
|
1554 | of resource limits), causing C<accept> to fail with C<ENFILE> but not |
|
|
1555 | rejecting the connection, leading to libev signalling readiness on |
|
|
1556 | the next iteration again (the connection still exists after all), and |
|
|
1557 | typically causing the program to loop at 100% CPU usage. |
|
|
1558 | |
|
|
1559 | Unfortunately, the set of errors that cause this issue differs between |
|
|
1560 | operating systems, there is usually little the app can do to remedy the |
|
|
1561 | situation, and no known thread-safe method of removing the connection to |
|
|
1562 | cope with overload is known (to me). |
|
|
1563 | |
|
|
1564 | One of the easiest ways to handle this situation is to just ignore it |
|
|
1565 | - when the program encounters an overload, it will just loop until the |
|
|
1566 | situation is over. While this is a form of busy waiting, no OS offers an |
|
|
1567 | event-based way to handle this situation, so it's the best one can do. |
|
|
1568 | |
|
|
1569 | A better way to handle the situation is to log any errors other than |
|
|
1570 | C<EAGAIN> and C<EWOULDBLOCK>, making sure not to flood the log with such |
|
|
1571 | messages, and continue as usual, which at least gives the user an idea of |
|
|
1572 | what could be wrong ("raise the ulimit!"). For extra points one could stop |
|
|
1573 | the C<ev_io> watcher on the listening fd "for a while", which reduces CPU |
|
|
1574 | usage. |
|
|
1575 | |
|
|
1576 | If your program is single-threaded, then you could also keep a dummy file |
|
|
1577 | descriptor for overload situations (e.g. by opening F</dev/null>), and |
|
|
1578 | when you run into C<ENFILE> or C<EMFILE>, close it, run C<accept>, |
|
|
1579 | close that fd, and create a new dummy fd. This will gracefully refuse |
|
|
1580 | clients under typical overload conditions. |
|
|
1581 | |
|
|
1582 | The last way to handle it is to simply log the error and C<exit>, as |
|
|
1583 | is often done with C<malloc> failures, but this results in an easy |
|
|
1584 | opportunity for a DoS attack. |
1263 | |
1585 | |
1264 | =head3 Watcher-Specific Functions |
1586 | =head3 Watcher-Specific Functions |
1265 | |
1587 | |
1266 | =over 4 |
1588 | =over 4 |
1267 | |
1589 | |
… | |
… | |
1314 | year, it will still time out after (roughly) one hour. "Roughly" because |
1636 | year, it will still time out after (roughly) one hour. "Roughly" because |
1315 | detecting time jumps is hard, and some inaccuracies are unavoidable (the |
1637 | detecting time jumps is hard, and some inaccuracies are unavoidable (the |
1316 | monotonic clock option helps a lot here). |
1638 | monotonic clock option helps a lot here). |
1317 | |
1639 | |
1318 | The callback is guaranteed to be invoked only I<after> its timeout has |
1640 | The callback is guaranteed to be invoked only I<after> its timeout has |
1319 | passed, but if multiple timers become ready during the same loop iteration |
1641 | passed (not I<at>, so on systems with very low-resolution clocks this |
1320 | then order of execution is undefined. |
1642 | might introduce a small delay). If multiple timers become ready during the |
|
|
1643 | same loop iteration then the ones with earlier time-out values are invoked |
|
|
1644 | before ones of the same priority with later time-out values (but this is |
|
|
1645 | no longer true when a callback calls C<ev_loop> recursively). |
1321 | |
1646 | |
1322 | =head3 Be smart about timeouts |
1647 | =head3 Be smart about timeouts |
1323 | |
1648 | |
1324 | Many real-world problems involve some kind of timeout, usually for error |
1649 | Many real-world problems involve some kind of timeout, usually for error |
1325 | recovery. A typical example is an HTTP request - if the other side hangs, |
1650 | recovery. A typical example is an HTTP request - if the other side hangs, |
… | |
… | |
1369 | C<after> argument to C<ev_timer_set>, and only ever use the C<repeat> |
1694 | C<after> argument to C<ev_timer_set>, and only ever use the C<repeat> |
1370 | member and C<ev_timer_again>. |
1695 | member and C<ev_timer_again>. |
1371 | |
1696 | |
1372 | At start: |
1697 | At start: |
1373 | |
1698 | |
1374 | ev_timer_init (timer, callback); |
1699 | ev_init (timer, callback); |
1375 | timer->repeat = 60.; |
1700 | timer->repeat = 60.; |
1376 | ev_timer_again (loop, timer); |
1701 | ev_timer_again (loop, timer); |
1377 | |
1702 | |
1378 | Each time there is some activity: |
1703 | Each time there is some activity: |
1379 | |
1704 | |
… | |
… | |
1418 | else |
1743 | else |
1419 | { |
1744 | { |
1420 | // callback was invoked, but there was some activity, re-arm |
1745 | // callback was invoked, but there was some activity, re-arm |
1421 | // the watcher to fire in last_activity + 60, which is |
1746 | // the watcher to fire in last_activity + 60, which is |
1422 | // guaranteed to be in the future, so "again" is positive: |
1747 | // guaranteed to be in the future, so "again" is positive: |
1423 | w->again = timeout - now; |
1748 | w->repeat = timeout - now; |
1424 | ev_timer_again (EV_A_ w); |
1749 | ev_timer_again (EV_A_ w); |
1425 | } |
1750 | } |
1426 | } |
1751 | } |
1427 | |
1752 | |
1428 | To summarise the callback: first calculate the real timeout (defined |
1753 | To summarise the callback: first calculate the real timeout (defined |
… | |
… | |
1441 | |
1766 | |
1442 | To start the timer, simply initialise the watcher and set C<last_activity> |
1767 | To start the timer, simply initialise the watcher and set C<last_activity> |
1443 | to the current time (meaning we just have some activity :), then call the |
1768 | to the current time (meaning we just have some activity :), then call the |
1444 | callback, which will "do the right thing" and start the timer: |
1769 | callback, which will "do the right thing" and start the timer: |
1445 | |
1770 | |
1446 | ev_timer_init (timer, callback); |
1771 | ev_init (timer, callback); |
1447 | last_activity = ev_now (loop); |
1772 | last_activity = ev_now (loop); |
1448 | callback (loop, timer, EV_TIMEOUT); |
1773 | callback (loop, timer, EV_TIMER); |
1449 | |
1774 | |
1450 | And when there is some activity, simply store the current time in |
1775 | And when there is some activity, simply store the current time in |
1451 | C<last_activity>, no libev calls at all: |
1776 | C<last_activity>, no libev calls at all: |
1452 | |
1777 | |
1453 | last_actiivty = ev_now (loop); |
1778 | last_actiivty = ev_now (loop); |
… | |
… | |
1512 | |
1837 | |
1513 | If the event loop is suspended for a long time, you can also force an |
1838 | If the event loop is suspended for a long time, you can also force an |
1514 | update of the time returned by C<ev_now ()> by calling C<ev_now_update |
1839 | update of the time returned by C<ev_now ()> by calling C<ev_now_update |
1515 | ()>. |
1840 | ()>. |
1516 | |
1841 | |
|
|
1842 | =head3 The special problems of suspended animation |
|
|
1843 | |
|
|
1844 | When you leave the server world it is quite customary to hit machines that |
|
|
1845 | can suspend/hibernate - what happens to the clocks during such a suspend? |
|
|
1846 | |
|
|
1847 | Some quick tests made with a Linux 2.6.28 indicate that a suspend freezes |
|
|
1848 | all processes, while the clocks (C<times>, C<CLOCK_MONOTONIC>) continue |
|
|
1849 | to run until the system is suspended, but they will not advance while the |
|
|
1850 | system is suspended. That means, on resume, it will be as if the program |
|
|
1851 | was frozen for a few seconds, but the suspend time will not be counted |
|
|
1852 | towards C<ev_timer> when a monotonic clock source is used. The real time |
|
|
1853 | clock advanced as expected, but if it is used as sole clocksource, then a |
|
|
1854 | long suspend would be detected as a time jump by libev, and timers would |
|
|
1855 | be adjusted accordingly. |
|
|
1856 | |
|
|
1857 | I would not be surprised to see different behaviour in different between |
|
|
1858 | operating systems, OS versions or even different hardware. |
|
|
1859 | |
|
|
1860 | The other form of suspend (job control, or sending a SIGSTOP) will see a |
|
|
1861 | time jump in the monotonic clocks and the realtime clock. If the program |
|
|
1862 | is suspended for a very long time, and monotonic clock sources are in use, |
|
|
1863 | then you can expect C<ev_timer>s to expire as the full suspension time |
|
|
1864 | will be counted towards the timers. When no monotonic clock source is in |
|
|
1865 | use, then libev will again assume a timejump and adjust accordingly. |
|
|
1866 | |
|
|
1867 | It might be beneficial for this latter case to call C<ev_suspend> |
|
|
1868 | and C<ev_resume> in code that handles C<SIGTSTP>, to at least get |
|
|
1869 | deterministic behaviour in this case (you can do nothing against |
|
|
1870 | C<SIGSTOP>). |
|
|
1871 | |
1517 | =head3 Watcher-Specific Functions and Data Members |
1872 | =head3 Watcher-Specific Functions and Data Members |
1518 | |
1873 | |
1519 | =over 4 |
1874 | =over 4 |
1520 | |
1875 | |
1521 | =item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat) |
1876 | =item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat) |
… | |
… | |
1544 | If the timer is started but non-repeating, stop it (as if it timed out). |
1899 | If the timer is started but non-repeating, stop it (as if it timed out). |
1545 | |
1900 | |
1546 | If the timer is repeating, either start it if necessary (with the |
1901 | If the timer is repeating, either start it if necessary (with the |
1547 | C<repeat> value), or reset the running timer to the C<repeat> value. |
1902 | C<repeat> value), or reset the running timer to the C<repeat> value. |
1548 | |
1903 | |
1549 | This sounds a bit complicated, see "Be smart about timeouts", above, for a |
1904 | This sounds a bit complicated, see L<Be smart about timeouts>, above, for a |
1550 | usage example. |
1905 | usage example. |
|
|
1906 | |
|
|
1907 | =item ev_tstamp ev_timer_remaining (loop, ev_timer *) |
|
|
1908 | |
|
|
1909 | Returns the remaining time until a timer fires. If the timer is active, |
|
|
1910 | then this time is relative to the current event loop time, otherwise it's |
|
|
1911 | the timeout value currently configured. |
|
|
1912 | |
|
|
1913 | That is, after an C<ev_timer_set (w, 5, 7)>, C<ev_timer_remaining> returns |
|
|
1914 | C<5>. When the timer is started and one second passes, C<ev_timer_remaining> |
|
|
1915 | will return C<4>. When the timer expires and is restarted, it will return |
|
|
1916 | roughly C<7> (likely slightly less as callback invocation takes some time, |
|
|
1917 | too), and so on. |
1551 | |
1918 | |
1552 | =item ev_tstamp repeat [read-write] |
1919 | =item ev_tstamp repeat [read-write] |
1553 | |
1920 | |
1554 | The current C<repeat> value. Will be used each time the watcher times out |
1921 | The current C<repeat> value. Will be used each time the watcher times out |
1555 | or C<ev_timer_again> is called, and determines the next timeout (if any), |
1922 | or C<ev_timer_again> is called, and determines the next timeout (if any), |
… | |
… | |
1593 | =head2 C<ev_periodic> - to cron or not to cron? |
1960 | =head2 C<ev_periodic> - to cron or not to cron? |
1594 | |
1961 | |
1595 | Periodic watchers are also timers of a kind, but they are very versatile |
1962 | Periodic watchers are also timers of a kind, but they are very versatile |
1596 | (and unfortunately a bit complex). |
1963 | (and unfortunately a bit complex). |
1597 | |
1964 | |
1598 | Unlike C<ev_timer>'s, they are not based on real time (or relative time) |
1965 | Unlike C<ev_timer>, periodic watchers are not based on real time (or |
1599 | but on wall clock time (absolute time). You can tell a periodic watcher |
1966 | relative time, the physical time that passes) but on wall clock time |
1600 | to trigger after some specific point in time. For example, if you tell a |
1967 | (absolute time, the thing you can read on your calender or clock). The |
1601 | periodic watcher to trigger in 10 seconds (by specifying e.g. C<ev_now () |
1968 | difference is that wall clock time can run faster or slower than real |
1602 | + 10.>, that is, an absolute time not a delay) and then reset your system |
1969 | time, and time jumps are not uncommon (e.g. when you adjust your |
1603 | clock to January of the previous year, then it will take more than year |
1970 | wrist-watch). |
1604 | to trigger the event (unlike an C<ev_timer>, which would still trigger |
|
|
1605 | roughly 10 seconds later as it uses a relative timeout). |
|
|
1606 | |
1971 | |
|
|
1972 | You can tell a periodic watcher to trigger after some specific point |
|
|
1973 | in time: for example, if you tell a periodic watcher to trigger "in 10 |
|
|
1974 | seconds" (by specifying e.g. C<ev_now () + 10.>, that is, an absolute time |
|
|
1975 | not a delay) and then reset your system clock to January of the previous |
|
|
1976 | year, then it will take a year or more to trigger the event (unlike an |
|
|
1977 | C<ev_timer>, which would still trigger roughly 10 seconds after starting |
|
|
1978 | it, as it uses a relative timeout). |
|
|
1979 | |
1607 | C<ev_periodic>s can also be used to implement vastly more complex timers, |
1980 | C<ev_periodic> watchers can also be used to implement vastly more complex |
1608 | such as triggering an event on each "midnight, local time", or other |
1981 | timers, such as triggering an event on each "midnight, local time", or |
1609 | complicated rules. |
1982 | other complicated rules. This cannot be done with C<ev_timer> watchers, as |
|
|
1983 | those cannot react to time jumps. |
1610 | |
1984 | |
1611 | As with timers, the callback is guaranteed to be invoked only when the |
1985 | As with timers, the callback is guaranteed to be invoked only when the |
1612 | time (C<at>) has passed, but if multiple periodic timers become ready |
1986 | point in time where it is supposed to trigger has passed. If multiple |
1613 | during the same loop iteration, then order of execution is undefined. |
1987 | timers become ready during the same loop iteration then the ones with |
|
|
1988 | earlier time-out values are invoked before ones with later time-out values |
|
|
1989 | (but this is no longer true when a callback calls C<ev_loop> recursively). |
1614 | |
1990 | |
1615 | =head3 Watcher-Specific Functions and Data Members |
1991 | =head3 Watcher-Specific Functions and Data Members |
1616 | |
1992 | |
1617 | =over 4 |
1993 | =over 4 |
1618 | |
1994 | |
1619 | =item ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb) |
1995 | =item ev_periodic_init (ev_periodic *, callback, ev_tstamp offset, ev_tstamp interval, reschedule_cb) |
1620 | |
1996 | |
1621 | =item ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb) |
1997 | =item ev_periodic_set (ev_periodic *, ev_tstamp offset, ev_tstamp interval, reschedule_cb) |
1622 | |
1998 | |
1623 | Lots of arguments, lets sort it out... There are basically three modes of |
1999 | Lots of arguments, let's sort it out... There are basically three modes of |
1624 | operation, and we will explain them from simplest to most complex: |
2000 | operation, and we will explain them from simplest to most complex: |
1625 | |
2001 | |
1626 | =over 4 |
2002 | =over 4 |
1627 | |
2003 | |
1628 | =item * absolute timer (at = time, interval = reschedule_cb = 0) |
2004 | =item * absolute timer (offset = absolute time, interval = 0, reschedule_cb = 0) |
1629 | |
2005 | |
1630 | In this configuration the watcher triggers an event after the wall clock |
2006 | In this configuration the watcher triggers an event after the wall clock |
1631 | time C<at> has passed. It will not repeat and will not adjust when a time |
2007 | time C<offset> has passed. It will not repeat and will not adjust when a |
1632 | jump occurs, that is, if it is to be run at January 1st 2011 then it will |
2008 | time jump occurs, that is, if it is to be run at January 1st 2011 then it |
1633 | only run when the system clock reaches or surpasses this time. |
2009 | will be stopped and invoked when the system clock reaches or surpasses |
|
|
2010 | this point in time. |
1634 | |
2011 | |
1635 | =item * repeating interval timer (at = offset, interval > 0, reschedule_cb = 0) |
2012 | =item * repeating interval timer (offset = offset within interval, interval > 0, reschedule_cb = 0) |
1636 | |
2013 | |
1637 | In this mode the watcher will always be scheduled to time out at the next |
2014 | In this mode the watcher will always be scheduled to time out at the next |
1638 | C<at + N * interval> time (for some integer N, which can also be negative) |
2015 | C<offset + N * interval> time (for some integer N, which can also be |
1639 | and then repeat, regardless of any time jumps. |
2016 | negative) and then repeat, regardless of any time jumps. The C<offset> |
|
|
2017 | argument is merely an offset into the C<interval> periods. |
1640 | |
2018 | |
1641 | This can be used to create timers that do not drift with respect to the |
2019 | This can be used to create timers that do not drift with respect to the |
1642 | system clock, for example, here is a C<ev_periodic> that triggers each |
2020 | system clock, for example, here is an C<ev_periodic> that triggers each |
1643 | hour, on the hour: |
2021 | hour, on the hour (with respect to UTC): |
1644 | |
2022 | |
1645 | ev_periodic_set (&periodic, 0., 3600., 0); |
2023 | ev_periodic_set (&periodic, 0., 3600., 0); |
1646 | |
2024 | |
1647 | This doesn't mean there will always be 3600 seconds in between triggers, |
2025 | This doesn't mean there will always be 3600 seconds in between triggers, |
1648 | but only that the callback will be called when the system time shows a |
2026 | but only that the callback will be called when the system time shows a |
1649 | full hour (UTC), or more correctly, when the system time is evenly divisible |
2027 | full hour (UTC), or more correctly, when the system time is evenly divisible |
1650 | by 3600. |
2028 | by 3600. |
1651 | |
2029 | |
1652 | Another way to think about it (for the mathematically inclined) is that |
2030 | Another way to think about it (for the mathematically inclined) is that |
1653 | C<ev_periodic> will try to run the callback in this mode at the next possible |
2031 | C<ev_periodic> will try to run the callback in this mode at the next possible |
1654 | time where C<time = at (mod interval)>, regardless of any time jumps. |
2032 | time where C<time = offset (mod interval)>, regardless of any time jumps. |
1655 | |
2033 | |
1656 | For numerical stability it is preferable that the C<at> value is near |
2034 | For numerical stability it is preferable that the C<offset> value is near |
1657 | C<ev_now ()> (the current time), but there is no range requirement for |
2035 | C<ev_now ()> (the current time), but there is no range requirement for |
1658 | this value, and in fact is often specified as zero. |
2036 | this value, and in fact is often specified as zero. |
1659 | |
2037 | |
1660 | Note also that there is an upper limit to how often a timer can fire (CPU |
2038 | Note also that there is an upper limit to how often a timer can fire (CPU |
1661 | speed for example), so if C<interval> is very small then timing stability |
2039 | speed for example), so if C<interval> is very small then timing stability |
1662 | will of course deteriorate. Libev itself tries to be exact to be about one |
2040 | will of course deteriorate. Libev itself tries to be exact to be about one |
1663 | millisecond (if the OS supports it and the machine is fast enough). |
2041 | millisecond (if the OS supports it and the machine is fast enough). |
1664 | |
2042 | |
1665 | =item * manual reschedule mode (at and interval ignored, reschedule_cb = callback) |
2043 | =item * manual reschedule mode (offset ignored, interval ignored, reschedule_cb = callback) |
1666 | |
2044 | |
1667 | In this mode the values for C<interval> and C<at> are both being |
2045 | In this mode the values for C<interval> and C<offset> are both being |
1668 | ignored. Instead, each time the periodic watcher gets scheduled, the |
2046 | ignored. Instead, each time the periodic watcher gets scheduled, the |
1669 | reschedule callback will be called with the watcher as first, and the |
2047 | reschedule callback will be called with the watcher as first, and the |
1670 | current time as second argument. |
2048 | current time as second argument. |
1671 | |
2049 | |
1672 | NOTE: I<This callback MUST NOT stop or destroy any periodic watcher, |
2050 | NOTE: I<This callback MUST NOT stop or destroy any periodic watcher, ever, |
1673 | ever, or make ANY event loop modifications whatsoever>. |
2051 | or make ANY other event loop modifications whatsoever, unless explicitly |
|
|
2052 | allowed by documentation here>. |
1674 | |
2053 | |
1675 | If you need to stop it, return C<now + 1e30> (or so, fudge fudge) and stop |
2054 | If you need to stop it, return C<now + 1e30> (or so, fudge fudge) and stop |
1676 | it afterwards (e.g. by starting an C<ev_prepare> watcher, which is the |
2055 | it afterwards (e.g. by starting an C<ev_prepare> watcher, which is the |
1677 | only event loop modification you are allowed to do). |
2056 | only event loop modification you are allowed to do). |
1678 | |
2057 | |
… | |
… | |
1708 | a different time than the last time it was called (e.g. in a crond like |
2087 | a different time than the last time it was called (e.g. in a crond like |
1709 | program when the crontabs have changed). |
2088 | program when the crontabs have changed). |
1710 | |
2089 | |
1711 | =item ev_tstamp ev_periodic_at (ev_periodic *) |
2090 | =item ev_tstamp ev_periodic_at (ev_periodic *) |
1712 | |
2091 | |
1713 | When active, returns the absolute time that the watcher is supposed to |
2092 | When active, returns the absolute time that the watcher is supposed |
1714 | trigger next. |
2093 | to trigger next. This is not the same as the C<offset> argument to |
|
|
2094 | C<ev_periodic_set>, but indeed works even in interval and manual |
|
|
2095 | rescheduling modes. |
1715 | |
2096 | |
1716 | =item ev_tstamp offset [read-write] |
2097 | =item ev_tstamp offset [read-write] |
1717 | |
2098 | |
1718 | When repeating, this contains the offset value, otherwise this is the |
2099 | When repeating, this contains the offset value, otherwise this is the |
1719 | absolute point in time (the C<at> value passed to C<ev_periodic_set>). |
2100 | absolute point in time (the C<offset> value passed to C<ev_periodic_set>, |
|
|
2101 | although libev might modify this value for better numerical stability). |
1720 | |
2102 | |
1721 | Can be modified any time, but changes only take effect when the periodic |
2103 | Can be modified any time, but changes only take effect when the periodic |
1722 | timer fires or C<ev_periodic_again> is being called. |
2104 | timer fires or C<ev_periodic_again> is being called. |
1723 | |
2105 | |
1724 | =item ev_tstamp interval [read-write] |
2106 | =item ev_tstamp interval [read-write] |
… | |
… | |
1776 | Signal watchers will trigger an event when the process receives a specific |
2158 | Signal watchers will trigger an event when the process receives a specific |
1777 | signal one or more times. Even though signals are very asynchronous, libev |
2159 | signal one or more times. Even though signals are very asynchronous, libev |
1778 | will try it's best to deliver signals synchronously, i.e. as part of the |
2160 | will try it's best to deliver signals synchronously, i.e. as part of the |
1779 | normal event processing, like any other event. |
2161 | normal event processing, like any other event. |
1780 | |
2162 | |
1781 | If you want signals asynchronously, just use C<sigaction> as you would |
2163 | If you want signals to be delivered truly asynchronously, just use |
1782 | do without libev and forget about sharing the signal. You can even use |
2164 | C<sigaction> as you would do without libev and forget about sharing |
1783 | C<ev_async> from a signal handler to synchronously wake up an event loop. |
2165 | the signal. You can even use C<ev_async> from a signal handler to |
|
|
2166 | synchronously wake up an event loop. |
1784 | |
2167 | |
1785 | You can configure as many watchers as you like per signal. Only when the |
2168 | You can configure as many watchers as you like for the same signal, but |
|
|
2169 | only within the same loop, i.e. you can watch for C<SIGINT> in your |
|
|
2170 | default loop and for C<SIGIO> in another loop, but you cannot watch for |
|
|
2171 | C<SIGINT> in both the default loop and another loop at the same time. At |
|
|
2172 | the moment, C<SIGCHLD> is permanently tied to the default loop. |
|
|
2173 | |
1786 | first watcher gets started will libev actually register a signal handler |
2174 | When the first watcher gets started will libev actually register something |
1787 | with the kernel (thus it coexists with your own signal handlers as long as |
2175 | with the kernel (thus it coexists with your own signal handlers as long as |
1788 | you don't register any with libev for the same signal). Similarly, when |
2176 | you don't register any with libev for the same signal). |
1789 | the last signal watcher for a signal is stopped, libev will reset the |
|
|
1790 | signal handler to SIG_DFL (regardless of what it was set to before). |
|
|
1791 | |
2177 | |
1792 | If possible and supported, libev will install its handlers with |
2178 | If possible and supported, libev will install its handlers with |
1793 | C<SA_RESTART> behaviour enabled, so system calls should not be unduly |
2179 | C<SA_RESTART> (or equivalent) behaviour enabled, so system calls should |
1794 | interrupted. If you have a problem with system calls getting interrupted by |
2180 | not be unduly interrupted. If you have a problem with system calls getting |
1795 | signals you can block all signals in an C<ev_check> watcher and unblock |
2181 | interrupted by signals you can block all signals in an C<ev_check> watcher |
1796 | them in an C<ev_prepare> watcher. |
2182 | and unblock them in an C<ev_prepare> watcher. |
|
|
2183 | |
|
|
2184 | =head3 The special problem of inheritance over fork/execve/pthread_create |
|
|
2185 | |
|
|
2186 | Both the signal mask (C<sigprocmask>) and the signal disposition |
|
|
2187 | (C<sigaction>) are unspecified after starting a signal watcher (and after |
|
|
2188 | stopping it again), that is, libev might or might not block the signal, |
|
|
2189 | and might or might not set or restore the installed signal handler. |
|
|
2190 | |
|
|
2191 | While this does not matter for the signal disposition (libev never |
|
|
2192 | sets signals to C<SIG_IGN>, so handlers will be reset to C<SIG_DFL> on |
|
|
2193 | C<execve>), this matters for the signal mask: many programs do not expect |
|
|
2194 | certain signals to be blocked. |
|
|
2195 | |
|
|
2196 | This means that before calling C<exec> (from the child) you should reset |
|
|
2197 | the signal mask to whatever "default" you expect (all clear is a good |
|
|
2198 | choice usually). |
|
|
2199 | |
|
|
2200 | The simplest way to ensure that the signal mask is reset in the child is |
|
|
2201 | to install a fork handler with C<pthread_atfork> that resets it. That will |
|
|
2202 | catch fork calls done by libraries (such as the libc) as well. |
|
|
2203 | |
|
|
2204 | In current versions of libev, the signal will not be blocked indefinitely |
|
|
2205 | unless you use the C<signalfd> API (C<EV_SIGNALFD>). While this reduces |
|
|
2206 | the window of opportunity for problems, it will not go away, as libev |
|
|
2207 | I<has> to modify the signal mask, at least temporarily. |
|
|
2208 | |
|
|
2209 | So I can't stress this enough: I<If you do not reset your signal mask when |
|
|
2210 | you expect it to be empty, you have a race condition in your code>. This |
|
|
2211 | is not a libev-specific thing, this is true for most event libraries. |
1797 | |
2212 | |
1798 | =head3 Watcher-Specific Functions and Data Members |
2213 | =head3 Watcher-Specific Functions and Data Members |
1799 | |
2214 | |
1800 | =over 4 |
2215 | =over 4 |
1801 | |
2216 | |
… | |
… | |
1833 | some child status changes (most typically when a child of yours dies or |
2248 | some child status changes (most typically when a child of yours dies or |
1834 | exits). It is permissible to install a child watcher I<after> the child |
2249 | exits). It is permissible to install a child watcher I<after> the child |
1835 | has been forked (which implies it might have already exited), as long |
2250 | has been forked (which implies it might have already exited), as long |
1836 | as the event loop isn't entered (or is continued from a watcher), i.e., |
2251 | as the event loop isn't entered (or is continued from a watcher), i.e., |
1837 | forking and then immediately registering a watcher for the child is fine, |
2252 | forking and then immediately registering a watcher for the child is fine, |
1838 | but forking and registering a watcher a few event loop iterations later is |
2253 | but forking and registering a watcher a few event loop iterations later or |
1839 | not. |
2254 | in the next callback invocation is not. |
1840 | |
2255 | |
1841 | Only the default event loop is capable of handling signals, and therefore |
2256 | Only the default event loop is capable of handling signals, and therefore |
1842 | you can only register child watchers in the default event loop. |
2257 | you can only register child watchers in the default event loop. |
1843 | |
2258 | |
|
|
2259 | Due to some design glitches inside libev, child watchers will always be |
|
|
2260 | handled at maximum priority (their priority is set to C<EV_MAXPRI> by |
|
|
2261 | libev) |
|
|
2262 | |
1844 | =head3 Process Interaction |
2263 | =head3 Process Interaction |
1845 | |
2264 | |
1846 | Libev grabs C<SIGCHLD> as soon as the default event loop is |
2265 | Libev grabs C<SIGCHLD> as soon as the default event loop is |
1847 | initialised. This is necessary to guarantee proper behaviour even if |
2266 | initialised. This is necessary to guarantee proper behaviour even if the |
1848 | the first child watcher is started after the child exits. The occurrence |
2267 | first child watcher is started after the child exits. The occurrence |
1849 | of C<SIGCHLD> is recorded asynchronously, but child reaping is done |
2268 | of C<SIGCHLD> is recorded asynchronously, but child reaping is done |
1850 | synchronously as part of the event loop processing. Libev always reaps all |
2269 | synchronously as part of the event loop processing. Libev always reaps all |
1851 | children, even ones not watched. |
2270 | children, even ones not watched. |
1852 | |
2271 | |
1853 | =head3 Overriding the Built-In Processing |
2272 | =head3 Overriding the Built-In Processing |
… | |
… | |
1863 | =head3 Stopping the Child Watcher |
2282 | =head3 Stopping the Child Watcher |
1864 | |
2283 | |
1865 | Currently, the child watcher never gets stopped, even when the |
2284 | Currently, the child watcher never gets stopped, even when the |
1866 | child terminates, so normally one needs to stop the watcher in the |
2285 | child terminates, so normally one needs to stop the watcher in the |
1867 | callback. Future versions of libev might stop the watcher automatically |
2286 | callback. Future versions of libev might stop the watcher automatically |
1868 | when a child exit is detected. |
2287 | when a child exit is detected (calling C<ev_child_stop> twice is not a |
|
|
2288 | problem). |
1869 | |
2289 | |
1870 | =head3 Watcher-Specific Functions and Data Members |
2290 | =head3 Watcher-Specific Functions and Data Members |
1871 | |
2291 | |
1872 | =over 4 |
2292 | =over 4 |
1873 | |
2293 | |
… | |
… | |
2009 | the process. The exception are C<ev_stat> watchers - those call C<stat |
2429 | the process. The exception are C<ev_stat> watchers - those call C<stat |
2010 | ()>, which is a synchronous operation. |
2430 | ()>, which is a synchronous operation. |
2011 | |
2431 | |
2012 | For local paths, this usually doesn't matter: unless the system is very |
2432 | For local paths, this usually doesn't matter: unless the system is very |
2013 | busy or the intervals between stat's are large, a stat call will be fast, |
2433 | busy or the intervals between stat's are large, a stat call will be fast, |
2014 | as the path data is suually in memory already (except when starting the |
2434 | as the path data is usually in memory already (except when starting the |
2015 | watcher). |
2435 | watcher). |
2016 | |
2436 | |
2017 | For networked file systems, calling C<stat ()> can block an indefinite |
2437 | For networked file systems, calling C<stat ()> can block an indefinite |
2018 | time due to network issues, and even under good conditions, a stat call |
2438 | time due to network issues, and even under good conditions, a stat call |
2019 | often takes multiple milliseconds. |
2439 | often takes multiple milliseconds. |
… | |
… | |
2176 | |
2596 | |
2177 | =head3 Watcher-Specific Functions and Data Members |
2597 | =head3 Watcher-Specific Functions and Data Members |
2178 | |
2598 | |
2179 | =over 4 |
2599 | =over 4 |
2180 | |
2600 | |
2181 | =item ev_idle_init (ev_signal *, callback) |
2601 | =item ev_idle_init (ev_idle *, callback) |
2182 | |
2602 | |
2183 | Initialises and configures the idle watcher - it has no parameters of any |
2603 | Initialises and configures the idle watcher - it has no parameters of any |
2184 | kind. There is a C<ev_idle_set> macro, but using it is utterly pointless, |
2604 | kind. There is a C<ev_idle_set> macro, but using it is utterly pointless, |
2185 | believe me. |
2605 | believe me. |
2186 | |
2606 | |
… | |
… | |
2199 | // no longer anything immediate to do. |
2619 | // no longer anything immediate to do. |
2200 | } |
2620 | } |
2201 | |
2621 | |
2202 | ev_idle *idle_watcher = malloc (sizeof (ev_idle)); |
2622 | ev_idle *idle_watcher = malloc (sizeof (ev_idle)); |
2203 | ev_idle_init (idle_watcher, idle_cb); |
2623 | ev_idle_init (idle_watcher, idle_cb); |
2204 | ev_idle_start (loop, idle_cb); |
2624 | ev_idle_start (loop, idle_watcher); |
2205 | |
2625 | |
2206 | |
2626 | |
2207 | =head2 C<ev_prepare> and C<ev_check> - customise your event loop! |
2627 | =head2 C<ev_prepare> and C<ev_check> - customise your event loop! |
2208 | |
2628 | |
2209 | Prepare and check watchers are usually (but not always) used in pairs: |
2629 | Prepare and check watchers are usually (but not always) used in pairs: |
… | |
… | |
2302 | struct pollfd fds [nfd]; |
2722 | struct pollfd fds [nfd]; |
2303 | // actual code will need to loop here and realloc etc. |
2723 | // actual code will need to loop here and realloc etc. |
2304 | adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
2724 | adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
2305 | |
2725 | |
2306 | /* the callback is illegal, but won't be called as we stop during check */ |
2726 | /* the callback is illegal, but won't be called as we stop during check */ |
2307 | ev_timer_init (&tw, 0, timeout * 1e-3); |
2727 | ev_timer_init (&tw, 0, timeout * 1e-3, 0.); |
2308 | ev_timer_start (loop, &tw); |
2728 | ev_timer_start (loop, &tw); |
2309 | |
2729 | |
2310 | // create one ev_io per pollfd |
2730 | // create one ev_io per pollfd |
2311 | for (int i = 0; i < nfd; ++i) |
2731 | for (int i = 0; i < nfd; ++i) |
2312 | { |
2732 | { |
… | |
… | |
2425 | some fds have to be watched and handled very quickly (with low latency), |
2845 | some fds have to be watched and handled very quickly (with low latency), |
2426 | and even priorities and idle watchers might have too much overhead. In |
2846 | and even priorities and idle watchers might have too much overhead. In |
2427 | this case you would put all the high priority stuff in one loop and all |
2847 | this case you would put all the high priority stuff in one loop and all |
2428 | the rest in a second one, and embed the second one in the first. |
2848 | the rest in a second one, and embed the second one in the first. |
2429 | |
2849 | |
2430 | As long as the watcher is active, the callback will be invoked every time |
2850 | As long as the watcher is active, the callback will be invoked every |
2431 | there might be events pending in the embedded loop. The callback must then |
2851 | time there might be events pending in the embedded loop. The callback |
2432 | call C<ev_embed_sweep (mainloop, watcher)> to make a single sweep and invoke |
2852 | must then call C<ev_embed_sweep (mainloop, watcher)> to make a single |
2433 | their callbacks (you could also start an idle watcher to give the embedded |
2853 | sweep and invoke their callbacks (the callback doesn't need to invoke the |
2434 | loop strictly lower priority for example). You can also set the callback |
2854 | C<ev_embed_sweep> function directly, it could also start an idle watcher |
2435 | to C<0>, in which case the embed watcher will automatically execute the |
2855 | to give the embedded loop strictly lower priority for example). |
2436 | embedded loop sweep. |
|
|
2437 | |
2856 | |
2438 | As long as the watcher is started it will automatically handle events. The |
2857 | You can also set the callback to C<0>, in which case the embed watcher |
2439 | callback will be invoked whenever some events have been handled. You can |
2858 | will automatically execute the embedded loop sweep whenever necessary. |
2440 | set the callback to C<0> to avoid having to specify one if you are not |
|
|
2441 | interested in that. |
|
|
2442 | |
2859 | |
2443 | Also, there have not currently been made special provisions for forking: |
2860 | Fork detection will be handled transparently while the C<ev_embed> watcher |
2444 | when you fork, you not only have to call C<ev_loop_fork> on both loops, |
2861 | is active, i.e., the embedded loop will automatically be forked when the |
2445 | but you will also have to stop and restart any C<ev_embed> watchers |
2862 | embedding loop forks. In other cases, the user is responsible for calling |
2446 | yourself - but you can use a fork watcher to handle this automatically, |
2863 | C<ev_loop_fork> on the embedded loop. |
2447 | and future versions of libev might do just that. |
|
|
2448 | |
2864 | |
2449 | Unfortunately, not all backends are embeddable: only the ones returned by |
2865 | Unfortunately, not all backends are embeddable: only the ones returned by |
2450 | C<ev_embeddable_backends> are, which, unfortunately, does not include any |
2866 | C<ev_embeddable_backends> are, which, unfortunately, does not include any |
2451 | portable one. |
2867 | portable one. |
2452 | |
2868 | |
… | |
… | |
2546 | event loop blocks next and before C<ev_check> watchers are being called, |
2962 | event loop blocks next and before C<ev_check> watchers are being called, |
2547 | and only in the child after the fork. If whoever good citizen calling |
2963 | and only in the child after the fork. If whoever good citizen calling |
2548 | C<ev_default_fork> cheats and calls it in the wrong process, the fork |
2964 | C<ev_default_fork> cheats and calls it in the wrong process, the fork |
2549 | handlers will be invoked, too, of course. |
2965 | handlers will be invoked, too, of course. |
2550 | |
2966 | |
|
|
2967 | =head3 The special problem of life after fork - how is it possible? |
|
|
2968 | |
|
|
2969 | Most uses of C<fork()> consist of forking, then some simple calls to ste |
|
|
2970 | up/change the process environment, followed by a call to C<exec()>. This |
|
|
2971 | sequence should be handled by libev without any problems. |
|
|
2972 | |
|
|
2973 | This changes when the application actually wants to do event handling |
|
|
2974 | in the child, or both parent in child, in effect "continuing" after the |
|
|
2975 | fork. |
|
|
2976 | |
|
|
2977 | The default mode of operation (for libev, with application help to detect |
|
|
2978 | forks) is to duplicate all the state in the child, as would be expected |
|
|
2979 | when I<either> the parent I<or> the child process continues. |
|
|
2980 | |
|
|
2981 | When both processes want to continue using libev, then this is usually the |
|
|
2982 | wrong result. In that case, usually one process (typically the parent) is |
|
|
2983 | supposed to continue with all watchers in place as before, while the other |
|
|
2984 | process typically wants to start fresh, i.e. without any active watchers. |
|
|
2985 | |
|
|
2986 | The cleanest and most efficient way to achieve that with libev is to |
|
|
2987 | simply create a new event loop, which of course will be "empty", and |
|
|
2988 | use that for new watchers. This has the advantage of not touching more |
|
|
2989 | memory than necessary, and thus avoiding the copy-on-write, and the |
|
|
2990 | disadvantage of having to use multiple event loops (which do not support |
|
|
2991 | signal watchers). |
|
|
2992 | |
|
|
2993 | When this is not possible, or you want to use the default loop for |
|
|
2994 | other reasons, then in the process that wants to start "fresh", call |
|
|
2995 | C<ev_default_destroy ()> followed by C<ev_default_loop (...)>. Destroying |
|
|
2996 | the default loop will "orphan" (not stop) all registered watchers, so you |
|
|
2997 | have to be careful not to execute code that modifies those watchers. Note |
|
|
2998 | also that in that case, you have to re-register any signal watchers. |
|
|
2999 | |
2551 | =head3 Watcher-Specific Functions and Data Members |
3000 | =head3 Watcher-Specific Functions and Data Members |
2552 | |
3001 | |
2553 | =over 4 |
3002 | =over 4 |
2554 | |
3003 | |
2555 | =item ev_fork_init (ev_signal *, callback) |
3004 | =item ev_fork_init (ev_signal *, callback) |
… | |
… | |
2584 | =head3 Queueing |
3033 | =head3 Queueing |
2585 | |
3034 | |
2586 | C<ev_async> does not support queueing of data in any way. The reason |
3035 | C<ev_async> does not support queueing of data in any way. The reason |
2587 | is that the author does not know of a simple (or any) algorithm for a |
3036 | is that the author does not know of a simple (or any) algorithm for a |
2588 | multiple-writer-single-reader queue that works in all cases and doesn't |
3037 | multiple-writer-single-reader queue that works in all cases and doesn't |
2589 | need elaborate support such as pthreads. |
3038 | need elaborate support such as pthreads or unportable memory access |
|
|
3039 | semantics. |
2590 | |
3040 | |
2591 | That means that if you want to queue data, you have to provide your own |
3041 | That means that if you want to queue data, you have to provide your own |
2592 | queue. But at least I can tell you how to implement locking around your |
3042 | queue. But at least I can tell you how to implement locking around your |
2593 | queue: |
3043 | queue: |
2594 | |
3044 | |
… | |
… | |
2683 | an C<EV_ASYNC> event on the watcher into the event loop. Unlike |
3133 | an C<EV_ASYNC> event on the watcher into the event loop. Unlike |
2684 | C<ev_feed_event>, this call is safe to do from other threads, signal or |
3134 | C<ev_feed_event>, this call is safe to do from other threads, signal or |
2685 | similar contexts (see the discussion of C<EV_ATOMIC_T> in the embedding |
3135 | similar contexts (see the discussion of C<EV_ATOMIC_T> in the embedding |
2686 | section below on what exactly this means). |
3136 | section below on what exactly this means). |
2687 | |
3137 | |
|
|
3138 | Note that, as with other watchers in libev, multiple events might get |
|
|
3139 | compressed into a single callback invocation (another way to look at this |
|
|
3140 | is that C<ev_async> watchers are level-triggered, set on C<ev_async_send>, |
|
|
3141 | reset when the event loop detects that). |
|
|
3142 | |
2688 | This call incurs the overhead of a system call only once per loop iteration, |
3143 | This call incurs the overhead of a system call only once per event loop |
2689 | so while the overhead might be noticeable, it doesn't apply to repeated |
3144 | iteration, so while the overhead might be noticeable, it doesn't apply to |
2690 | calls to C<ev_async_send>. |
3145 | repeated calls to C<ev_async_send> for the same event loop. |
2691 | |
3146 | |
2692 | =item bool = ev_async_pending (ev_async *) |
3147 | =item bool = ev_async_pending (ev_async *) |
2693 | |
3148 | |
2694 | Returns a non-zero value when C<ev_async_send> has been called on the |
3149 | Returns a non-zero value when C<ev_async_send> has been called on the |
2695 | watcher but the event has not yet been processed (or even noted) by the |
3150 | watcher but the event has not yet been processed (or even noted) by the |
… | |
… | |
2698 | C<ev_async_send> sets a flag in the watcher and wakes up the loop. When |
3153 | C<ev_async_send> sets a flag in the watcher and wakes up the loop. When |
2699 | the loop iterates next and checks for the watcher to have become active, |
3154 | the loop iterates next and checks for the watcher to have become active, |
2700 | it will reset the flag again. C<ev_async_pending> can be used to very |
3155 | it will reset the flag again. C<ev_async_pending> can be used to very |
2701 | quickly check whether invoking the loop might be a good idea. |
3156 | quickly check whether invoking the loop might be a good idea. |
2702 | |
3157 | |
2703 | Not that this does I<not> check whether the watcher itself is pending, only |
3158 | Not that this does I<not> check whether the watcher itself is pending, |
2704 | whether it has been requested to make this watcher pending. |
3159 | only whether it has been requested to make this watcher pending: there |
|
|
3160 | is a time window between the event loop checking and resetting the async |
|
|
3161 | notification, and the callback being invoked. |
2705 | |
3162 | |
2706 | =back |
3163 | =back |
2707 | |
3164 | |
2708 | |
3165 | |
2709 | =head1 OTHER FUNCTIONS |
3166 | =head1 OTHER FUNCTIONS |
… | |
… | |
2726 | |
3183 | |
2727 | If C<timeout> is less than 0, then no timeout watcher will be |
3184 | If C<timeout> is less than 0, then no timeout watcher will be |
2728 | started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and |
3185 | started. Otherwise an C<ev_timer> watcher with after = C<timeout> (and |
2729 | repeat = 0) will be started. C<0> is a valid timeout. |
3186 | repeat = 0) will be started. C<0> is a valid timeout. |
2730 | |
3187 | |
2731 | The callback has the type C<void (*cb)(int revents, void *arg)> and gets |
3188 | The callback has the type C<void (*cb)(int revents, void *arg)> and is |
2732 | passed an C<revents> set like normal event callbacks (a combination of |
3189 | passed an C<revents> set like normal event callbacks (a combination of |
2733 | C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMEOUT>) and the C<arg> |
3190 | C<EV_ERROR>, C<EV_READ>, C<EV_WRITE> or C<EV_TIMER>) and the C<arg> |
2734 | value passed to C<ev_once>. Note that it is possible to receive I<both> |
3191 | value passed to C<ev_once>. Note that it is possible to receive I<both> |
2735 | a timeout and an io event at the same time - you probably should give io |
3192 | a timeout and an io event at the same time - you probably should give io |
2736 | events precedence. |
3193 | events precedence. |
2737 | |
3194 | |
2738 | Example: wait up to ten seconds for data to appear on STDIN_FILENO. |
3195 | Example: wait up to ten seconds for data to appear on STDIN_FILENO. |
2739 | |
3196 | |
2740 | static void stdin_ready (int revents, void *arg) |
3197 | static void stdin_ready (int revents, void *arg) |
2741 | { |
3198 | { |
2742 | if (revents & EV_READ) |
3199 | if (revents & EV_READ) |
2743 | /* stdin might have data for us, joy! */; |
3200 | /* stdin might have data for us, joy! */; |
2744 | else if (revents & EV_TIMEOUT) |
3201 | else if (revents & EV_TIMER) |
2745 | /* doh, nothing entered */; |
3202 | /* doh, nothing entered */; |
2746 | } |
3203 | } |
2747 | |
3204 | |
2748 | ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
3205 | ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
2749 | |
3206 | |
2750 | =item ev_feed_event (struct ev_loop *, watcher *, int revents) |
|
|
2751 | |
|
|
2752 | Feeds the given event set into the event loop, as if the specified event |
|
|
2753 | had happened for the specified watcher (which must be a pointer to an |
|
|
2754 | initialised but not necessarily started event watcher). |
|
|
2755 | |
|
|
2756 | =item ev_feed_fd_event (struct ev_loop *, int fd, int revents) |
3207 | =item ev_feed_fd_event (loop, int fd, int revents) |
2757 | |
3208 | |
2758 | Feed an event on the given fd, as if a file descriptor backend detected |
3209 | Feed an event on the given fd, as if a file descriptor backend detected |
2759 | the given events it. |
3210 | the given events it. |
2760 | |
3211 | |
2761 | =item ev_feed_signal_event (struct ev_loop *loop, int signum) |
3212 | =item ev_feed_signal_event (loop, int signum) |
2762 | |
3213 | |
2763 | Feed an event as if the given signal occurred (C<loop> must be the default |
3214 | Feed an event as if the given signal occurred (C<loop> must be the default |
2764 | loop!). |
3215 | loop!). |
2765 | |
3216 | |
2766 | =back |
3217 | =back |
… | |
… | |
2846 | |
3297 | |
2847 | =over 4 |
3298 | =over 4 |
2848 | |
3299 | |
2849 | =item ev::TYPE::TYPE () |
3300 | =item ev::TYPE::TYPE () |
2850 | |
3301 | |
2851 | =item ev::TYPE::TYPE (struct ev_loop *) |
3302 | =item ev::TYPE::TYPE (loop) |
2852 | |
3303 | |
2853 | =item ev::TYPE::~TYPE |
3304 | =item ev::TYPE::~TYPE |
2854 | |
3305 | |
2855 | The constructor (optionally) takes an event loop to associate the watcher |
3306 | The constructor (optionally) takes an event loop to associate the watcher |
2856 | with. If it is omitted, it will use C<EV_DEFAULT>. |
3307 | with. If it is omitted, it will use C<EV_DEFAULT>. |
… | |
… | |
2888 | |
3339 | |
2889 | myclass obj; |
3340 | myclass obj; |
2890 | ev::io iow; |
3341 | ev::io iow; |
2891 | iow.set <myclass, &myclass::io_cb> (&obj); |
3342 | iow.set <myclass, &myclass::io_cb> (&obj); |
2892 | |
3343 | |
|
|
3344 | =item w->set (object *) |
|
|
3345 | |
|
|
3346 | This is an B<experimental> feature that might go away in a future version. |
|
|
3347 | |
|
|
3348 | This is a variation of a method callback - leaving out the method to call |
|
|
3349 | will default the method to C<operator ()>, which makes it possible to use |
|
|
3350 | functor objects without having to manually specify the C<operator ()> all |
|
|
3351 | the time. Incidentally, you can then also leave out the template argument |
|
|
3352 | list. |
|
|
3353 | |
|
|
3354 | The C<operator ()> method prototype must be C<void operator ()(watcher &w, |
|
|
3355 | int revents)>. |
|
|
3356 | |
|
|
3357 | See the method-C<set> above for more details. |
|
|
3358 | |
|
|
3359 | Example: use a functor object as callback. |
|
|
3360 | |
|
|
3361 | struct myfunctor |
|
|
3362 | { |
|
|
3363 | void operator() (ev::io &w, int revents) |
|
|
3364 | { |
|
|
3365 | ... |
|
|
3366 | } |
|
|
3367 | } |
|
|
3368 | |
|
|
3369 | myfunctor f; |
|
|
3370 | |
|
|
3371 | ev::io w; |
|
|
3372 | w.set (&f); |
|
|
3373 | |
2893 | =item w->set<function> (void *data = 0) |
3374 | =item w->set<function> (void *data = 0) |
2894 | |
3375 | |
2895 | Also sets a callback, but uses a static method or plain function as |
3376 | Also sets a callback, but uses a static method or plain function as |
2896 | callback. The optional C<data> argument will be stored in the watcher's |
3377 | callback. The optional C<data> argument will be stored in the watcher's |
2897 | C<data> member and is free for you to use. |
3378 | C<data> member and is free for you to use. |
… | |
… | |
2903 | Example: Use a plain function as callback. |
3384 | Example: Use a plain function as callback. |
2904 | |
3385 | |
2905 | static void io_cb (ev::io &w, int revents) { } |
3386 | static void io_cb (ev::io &w, int revents) { } |
2906 | iow.set <io_cb> (); |
3387 | iow.set <io_cb> (); |
2907 | |
3388 | |
2908 | =item w->set (struct ev_loop *) |
3389 | =item w->set (loop) |
2909 | |
3390 | |
2910 | Associates a different C<struct ev_loop> with this watcher. You can only |
3391 | Associates a different C<struct ev_loop> with this watcher. You can only |
2911 | do this when the watcher is inactive (and not pending either). |
3392 | do this when the watcher is inactive (and not pending either). |
2912 | |
3393 | |
2913 | =item w->set ([arguments]) |
3394 | =item w->set ([arguments]) |
… | |
… | |
2983 | L<http://software.schmorp.de/pkg/EV>. |
3464 | L<http://software.schmorp.de/pkg/EV>. |
2984 | |
3465 | |
2985 | =item Python |
3466 | =item Python |
2986 | |
3467 | |
2987 | Python bindings can be found at L<http://code.google.com/p/pyev/>. It |
3468 | Python bindings can be found at L<http://code.google.com/p/pyev/>. It |
2988 | seems to be quite complete and well-documented. Note, however, that the |
3469 | seems to be quite complete and well-documented. |
2989 | patch they require for libev is outright dangerous as it breaks the ABI |
|
|
2990 | for everybody else, and therefore, should never be applied in an installed |
|
|
2991 | libev (if python requires an incompatible ABI then it needs to embed |
|
|
2992 | libev). |
|
|
2993 | |
3470 | |
2994 | =item Ruby |
3471 | =item Ruby |
2995 | |
3472 | |
2996 | Tony Arcieri has written a ruby extension that offers access to a subset |
3473 | Tony Arcieri has written a ruby extension that offers access to a subset |
2997 | of the libev API and adds file handle abstractions, asynchronous DNS and |
3474 | of the libev API and adds file handle abstractions, asynchronous DNS and |
2998 | more on top of it. It can be found via gem servers. Its homepage is at |
3475 | more on top of it. It can be found via gem servers. Its homepage is at |
2999 | L<http://rev.rubyforge.org/>. |
3476 | L<http://rev.rubyforge.org/>. |
3000 | |
3477 | |
|
|
3478 | Roger Pack reports that using the link order C<-lws2_32 -lmsvcrt-ruby-190> |
|
|
3479 | makes rev work even on mingw. |
|
|
3480 | |
|
|
3481 | =item Haskell |
|
|
3482 | |
|
|
3483 | A haskell binding to libev is available at |
|
|
3484 | L<http://hackage.haskell.org/cgi-bin/hackage-scripts/package/hlibev>. |
|
|
3485 | |
3001 | =item D |
3486 | =item D |
3002 | |
3487 | |
3003 | Leandro Lucarella has written a D language binding (F<ev.d>) for libev, to |
3488 | Leandro Lucarella has written a D language binding (F<ev.d>) for libev, to |
3004 | be found at L<http://proj.llucax.com.ar/wiki/evd>. |
3489 | be found at L<http://proj.llucax.com.ar/wiki/evd>. |
3005 | |
3490 | |
3006 | =item Ocaml |
3491 | =item Ocaml |
3007 | |
3492 | |
3008 | Erkki Seppala has written Ocaml bindings for libev, to be found at |
3493 | Erkki Seppala has written Ocaml bindings for libev, to be found at |
3009 | L<http://modeemi.cs.tut.fi/~flux/software/ocaml-ev/>. |
3494 | L<http://modeemi.cs.tut.fi/~flux/software/ocaml-ev/>. |
|
|
3495 | |
|
|
3496 | =item Lua |
|
|
3497 | |
|
|
3498 | Brian Maher has written a partial interface to libev for lua (at the |
|
|
3499 | time of this writing, only C<ev_io> and C<ev_timer>), to be found at |
|
|
3500 | L<http://github.com/brimworks/lua-ev>. |
3010 | |
3501 | |
3011 | =back |
3502 | =back |
3012 | |
3503 | |
3013 | |
3504 | |
3014 | =head1 MACRO MAGIC |
3505 | =head1 MACRO MAGIC |
… | |
… | |
3168 | libev.m4 |
3659 | libev.m4 |
3169 | |
3660 | |
3170 | =head2 PREPROCESSOR SYMBOLS/MACROS |
3661 | =head2 PREPROCESSOR SYMBOLS/MACROS |
3171 | |
3662 | |
3172 | Libev can be configured via a variety of preprocessor symbols you have to |
3663 | Libev can be configured via a variety of preprocessor symbols you have to |
3173 | define before including any of its files. The default in the absence of |
3664 | define before including (or compiling) any of its files. The default in |
3174 | autoconf is documented for every option. |
3665 | the absence of autoconf is documented for every option. |
|
|
3666 | |
|
|
3667 | Symbols marked with "(h)" do not change the ABI, and can have different |
|
|
3668 | values when compiling libev vs. including F<ev.h>, so it is permissible |
|
|
3669 | to redefine them before including F<ev.h> without breaking compatibility |
|
|
3670 | to a compiled library. All other symbols change the ABI, which means all |
|
|
3671 | users of libev and the libev code itself must be compiled with compatible |
|
|
3672 | settings. |
3175 | |
3673 | |
3176 | =over 4 |
3674 | =over 4 |
3177 | |
3675 | |
3178 | =item EV_STANDALONE |
3676 | =item EV_STANDALONE (h) |
3179 | |
3677 | |
3180 | Must always be C<1> if you do not use autoconf configuration, which |
3678 | Must always be C<1> if you do not use autoconf configuration, which |
3181 | keeps libev from including F<config.h>, and it also defines dummy |
3679 | keeps libev from including F<config.h>, and it also defines dummy |
3182 | implementations for some libevent functions (such as logging, which is not |
3680 | implementations for some libevent functions (such as logging, which is not |
3183 | supported). It will also not define any of the structs usually found in |
3681 | supported). It will also not define any of the structs usually found in |
3184 | F<event.h> that are not directly supported by the libev core alone. |
3682 | F<event.h> that are not directly supported by the libev core alone. |
3185 | |
3683 | |
|
|
3684 | In standalone mode, libev will still try to automatically deduce the |
|
|
3685 | configuration, but has to be more conservative. |
|
|
3686 | |
3186 | =item EV_USE_MONOTONIC |
3687 | =item EV_USE_MONOTONIC |
3187 | |
3688 | |
3188 | If defined to be C<1>, libev will try to detect the availability of the |
3689 | If defined to be C<1>, libev will try to detect the availability of the |
3189 | monotonic clock option at both compile time and runtime. Otherwise no use |
3690 | monotonic clock option at both compile time and runtime. Otherwise no |
3190 | of the monotonic clock option will be attempted. If you enable this, you |
3691 | use of the monotonic clock option will be attempted. If you enable this, |
3191 | usually have to link against librt or something similar. Enabling it when |
3692 | you usually have to link against librt or something similar. Enabling it |
3192 | the functionality isn't available is safe, though, although you have |
3693 | when the functionality isn't available is safe, though, although you have |
3193 | to make sure you link against any libraries where the C<clock_gettime> |
3694 | to make sure you link against any libraries where the C<clock_gettime> |
3194 | function is hiding in (often F<-lrt>). |
3695 | function is hiding in (often F<-lrt>). See also C<EV_USE_CLOCK_SYSCALL>. |
3195 | |
3696 | |
3196 | =item EV_USE_REALTIME |
3697 | =item EV_USE_REALTIME |
3197 | |
3698 | |
3198 | If defined to be C<1>, libev will try to detect the availability of the |
3699 | If defined to be C<1>, libev will try to detect the availability of the |
3199 | real-time clock option at compile time (and assume its availability at |
3700 | real-time clock option at compile time (and assume its availability |
3200 | runtime if successful). Otherwise no use of the real-time clock option will |
3701 | at runtime if successful). Otherwise no use of the real-time clock |
3201 | be attempted. This effectively replaces C<gettimeofday> by C<clock_get |
3702 | option will be attempted. This effectively replaces C<gettimeofday> |
3202 | (CLOCK_REALTIME, ...)> and will not normally affect correctness. See the |
3703 | by C<clock_get (CLOCK_REALTIME, ...)> and will not normally affect |
3203 | note about libraries in the description of C<EV_USE_MONOTONIC>, though. |
3704 | correctness. See the note about libraries in the description of |
|
|
3705 | C<EV_USE_MONOTONIC>, though. Defaults to the opposite value of |
|
|
3706 | C<EV_USE_CLOCK_SYSCALL>. |
|
|
3707 | |
|
|
3708 | =item EV_USE_CLOCK_SYSCALL |
|
|
3709 | |
|
|
3710 | If defined to be C<1>, libev will try to use a direct syscall instead |
|
|
3711 | of calling the system-provided C<clock_gettime> function. This option |
|
|
3712 | exists because on GNU/Linux, C<clock_gettime> is in C<librt>, but C<librt> |
|
|
3713 | unconditionally pulls in C<libpthread>, slowing down single-threaded |
|
|
3714 | programs needlessly. Using a direct syscall is slightly slower (in |
|
|
3715 | theory), because no optimised vdso implementation can be used, but avoids |
|
|
3716 | the pthread dependency. Defaults to C<1> on GNU/Linux with glibc 2.x or |
|
|
3717 | higher, as it simplifies linking (no need for C<-lrt>). |
3204 | |
3718 | |
3205 | =item EV_USE_NANOSLEEP |
3719 | =item EV_USE_NANOSLEEP |
3206 | |
3720 | |
3207 | If defined to be C<1>, libev will assume that C<nanosleep ()> is available |
3721 | If defined to be C<1>, libev will assume that C<nanosleep ()> is available |
3208 | and will use it for delays. Otherwise it will use C<select ()>. |
3722 | and will use it for delays. Otherwise it will use C<select ()>. |
… | |
… | |
3224 | |
3738 | |
3225 | =item EV_SELECT_USE_FD_SET |
3739 | =item EV_SELECT_USE_FD_SET |
3226 | |
3740 | |
3227 | If defined to C<1>, then the select backend will use the system C<fd_set> |
3741 | If defined to C<1>, then the select backend will use the system C<fd_set> |
3228 | structure. This is useful if libev doesn't compile due to a missing |
3742 | structure. This is useful if libev doesn't compile due to a missing |
3229 | C<NFDBITS> or C<fd_mask> definition or it mis-guesses the bitset layout on |
3743 | C<NFDBITS> or C<fd_mask> definition or it mis-guesses the bitset layout |
3230 | exotic systems. This usually limits the range of file descriptors to some |
3744 | on exotic systems. This usually limits the range of file descriptors to |
3231 | low limit such as 1024 or might have other limitations (winsocket only |
3745 | some low limit such as 1024 or might have other limitations (winsocket |
3232 | allows 64 sockets). The C<FD_SETSIZE> macro, set before compilation, might |
3746 | only allows 64 sockets). The C<FD_SETSIZE> macro, set before compilation, |
3233 | influence the size of the C<fd_set> used. |
3747 | configures the maximum size of the C<fd_set>. |
3234 | |
3748 | |
3235 | =item EV_SELECT_IS_WINSOCKET |
3749 | =item EV_SELECT_IS_WINSOCKET |
3236 | |
3750 | |
3237 | When defined to C<1>, the select backend will assume that |
3751 | When defined to C<1>, the select backend will assume that |
3238 | select/socket/connect etc. don't understand file descriptors but |
3752 | select/socket/connect etc. don't understand file descriptors but |
… | |
… | |
3240 | be used is the winsock select). This means that it will call |
3754 | be used is the winsock select). This means that it will call |
3241 | C<_get_osfhandle> on the fd to convert it to an OS handle. Otherwise, |
3755 | C<_get_osfhandle> on the fd to convert it to an OS handle. Otherwise, |
3242 | it is assumed that all these functions actually work on fds, even |
3756 | it is assumed that all these functions actually work on fds, even |
3243 | on win32. Should not be defined on non-win32 platforms. |
3757 | on win32. Should not be defined on non-win32 platforms. |
3244 | |
3758 | |
3245 | =item EV_FD_TO_WIN32_HANDLE |
3759 | =item EV_FD_TO_WIN32_HANDLE(fd) |
3246 | |
3760 | |
3247 | If C<EV_SELECT_IS_WINSOCKET> is enabled, then libev needs a way to map |
3761 | If C<EV_SELECT_IS_WINSOCKET> is enabled, then libev needs a way to map |
3248 | file descriptors to socket handles. When not defining this symbol (the |
3762 | file descriptors to socket handles. When not defining this symbol (the |
3249 | default), then libev will call C<_get_osfhandle>, which is usually |
3763 | default), then libev will call C<_get_osfhandle>, which is usually |
3250 | correct. In some cases, programs use their own file descriptor management, |
3764 | correct. In some cases, programs use their own file descriptor management, |
3251 | in which case they can provide this function to map fds to socket handles. |
3765 | in which case they can provide this function to map fds to socket handles. |
|
|
3766 | |
|
|
3767 | =item EV_WIN32_HANDLE_TO_FD(handle) |
|
|
3768 | |
|
|
3769 | If C<EV_SELECT_IS_WINSOCKET> then libev maps handles to file descriptors |
|
|
3770 | using the standard C<_open_osfhandle> function. For programs implementing |
|
|
3771 | their own fd to handle mapping, overwriting this function makes it easier |
|
|
3772 | to do so. This can be done by defining this macro to an appropriate value. |
|
|
3773 | |
|
|
3774 | =item EV_WIN32_CLOSE_FD(fd) |
|
|
3775 | |
|
|
3776 | If programs implement their own fd to handle mapping on win32, then this |
|
|
3777 | macro can be used to override the C<close> function, useful to unregister |
|
|
3778 | file descriptors again. Note that the replacement function has to close |
|
|
3779 | the underlying OS handle. |
3252 | |
3780 | |
3253 | =item EV_USE_POLL |
3781 | =item EV_USE_POLL |
3254 | |
3782 | |
3255 | If defined to be C<1>, libev will compile in support for the C<poll>(2) |
3783 | If defined to be C<1>, libev will compile in support for the C<poll>(2) |
3256 | backend. Otherwise it will be enabled on non-win32 platforms. It |
3784 | backend. Otherwise it will be enabled on non-win32 platforms. It |
… | |
… | |
3303 | as well as for signal and thread safety in C<ev_async> watchers. |
3831 | as well as for signal and thread safety in C<ev_async> watchers. |
3304 | |
3832 | |
3305 | In the absence of this define, libev will use C<sig_atomic_t volatile> |
3833 | In the absence of this define, libev will use C<sig_atomic_t volatile> |
3306 | (from F<signal.h>), which is usually good enough on most platforms. |
3834 | (from F<signal.h>), which is usually good enough on most platforms. |
3307 | |
3835 | |
3308 | =item EV_H |
3836 | =item EV_H (h) |
3309 | |
3837 | |
3310 | The name of the F<ev.h> header file used to include it. The default if |
3838 | The name of the F<ev.h> header file used to include it. The default if |
3311 | undefined is C<"ev.h"> in F<event.h>, F<ev.c> and F<ev++.h>. This can be |
3839 | undefined is C<"ev.h"> in F<event.h>, F<ev.c> and F<ev++.h>. This can be |
3312 | used to virtually rename the F<ev.h> header file in case of conflicts. |
3840 | used to virtually rename the F<ev.h> header file in case of conflicts. |
3313 | |
3841 | |
3314 | =item EV_CONFIG_H |
3842 | =item EV_CONFIG_H (h) |
3315 | |
3843 | |
3316 | If C<EV_STANDALONE> isn't C<1>, this variable can be used to override |
3844 | If C<EV_STANDALONE> isn't C<1>, this variable can be used to override |
3317 | F<ev.c>'s idea of where to find the F<config.h> file, similarly to |
3845 | F<ev.c>'s idea of where to find the F<config.h> file, similarly to |
3318 | C<EV_H>, above. |
3846 | C<EV_H>, above. |
3319 | |
3847 | |
3320 | =item EV_EVENT_H |
3848 | =item EV_EVENT_H (h) |
3321 | |
3849 | |
3322 | Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea |
3850 | Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea |
3323 | of how the F<event.h> header can be found, the default is C<"event.h">. |
3851 | of how the F<event.h> header can be found, the default is C<"event.h">. |
3324 | |
3852 | |
3325 | =item EV_PROTOTYPES |
3853 | =item EV_PROTOTYPES (h) |
3326 | |
3854 | |
3327 | If defined to be C<0>, then F<ev.h> will not define any function |
3855 | If defined to be C<0>, then F<ev.h> will not define any function |
3328 | prototypes, but still define all the structs and other symbols. This is |
3856 | prototypes, but still define all the structs and other symbols. This is |
3329 | occasionally useful if you want to provide your own wrapper functions |
3857 | occasionally useful if you want to provide your own wrapper functions |
3330 | around libev functions. |
3858 | around libev functions. |
… | |
… | |
3352 | fine. |
3880 | fine. |
3353 | |
3881 | |
3354 | If your embedding application does not need any priorities, defining these |
3882 | If your embedding application does not need any priorities, defining these |
3355 | both to C<0> will save some memory and CPU. |
3883 | both to C<0> will save some memory and CPU. |
3356 | |
3884 | |
3357 | =item EV_PERIODIC_ENABLE |
3885 | =item EV_PERIODIC_ENABLE, EV_IDLE_ENABLE, EV_EMBED_ENABLE, EV_STAT_ENABLE, |
|
|
3886 | EV_PREPARE_ENABLE, EV_CHECK_ENABLE, EV_FORK_ENABLE, EV_SIGNAL_ENABLE, |
|
|
3887 | EV_ASYNC_ENABLE, EV_CHILD_ENABLE. |
3358 | |
3888 | |
3359 | If undefined or defined to be C<1>, then periodic timers are supported. If |
3889 | If undefined or defined to be C<1> (and the platform supports it), then |
3360 | defined to be C<0>, then they are not. Disabling them saves a few kB of |
3890 | the respective watcher type is supported. If defined to be C<0>, then it |
3361 | code. |
3891 | is not. Disabling watcher types mainly saves codesize. |
3362 | |
3892 | |
3363 | =item EV_IDLE_ENABLE |
3893 | =item EV_FEATURES |
3364 | |
|
|
3365 | If undefined or defined to be C<1>, then idle watchers are supported. If |
|
|
3366 | defined to be C<0>, then they are not. Disabling them saves a few kB of |
|
|
3367 | code. |
|
|
3368 | |
|
|
3369 | =item EV_EMBED_ENABLE |
|
|
3370 | |
|
|
3371 | If undefined or defined to be C<1>, then embed watchers are supported. If |
|
|
3372 | defined to be C<0>, then they are not. Embed watchers rely on most other |
|
|
3373 | watcher types, which therefore must not be disabled. |
|
|
3374 | |
|
|
3375 | =item EV_STAT_ENABLE |
|
|
3376 | |
|
|
3377 | If undefined or defined to be C<1>, then stat watchers are supported. If |
|
|
3378 | defined to be C<0>, then they are not. |
|
|
3379 | |
|
|
3380 | =item EV_FORK_ENABLE |
|
|
3381 | |
|
|
3382 | If undefined or defined to be C<1>, then fork watchers are supported. If |
|
|
3383 | defined to be C<0>, then they are not. |
|
|
3384 | |
|
|
3385 | =item EV_ASYNC_ENABLE |
|
|
3386 | |
|
|
3387 | If undefined or defined to be C<1>, then async watchers are supported. If |
|
|
3388 | defined to be C<0>, then they are not. |
|
|
3389 | |
|
|
3390 | =item EV_MINIMAL |
|
|
3391 | |
3894 | |
3392 | If you need to shave off some kilobytes of code at the expense of some |
3895 | If you need to shave off some kilobytes of code at the expense of some |
3393 | speed, define this symbol to C<1>. Currently this is used to override some |
3896 | speed (but with the full API), you can define this symbol to request |
3394 | inlining decisions, saves roughly 30% code size on amd64. It also selects a |
3897 | certain subsets of functionality. The default is to enable all features |
3395 | much smaller 2-heap for timer management over the default 4-heap. |
3898 | that can be enabled on the platform. |
|
|
3899 | |
|
|
3900 | A typical way to use this symbol is to define it to C<0> (or to a bitset |
|
|
3901 | with some broad features you want) and then selectively re-enable |
|
|
3902 | additional parts you want, for example if you want everything minimal, |
|
|
3903 | but multiple event loop support, async and child watchers and the poll |
|
|
3904 | backend, use this: |
|
|
3905 | |
|
|
3906 | #define EV_FEATURES 0 |
|
|
3907 | #define EV_MULTIPLICITY 1 |
|
|
3908 | #define EV_USE_POLL 1 |
|
|
3909 | #define EV_CHILD_ENABLE 1 |
|
|
3910 | #define EV_ASYNC_ENABLE 1 |
|
|
3911 | |
|
|
3912 | The actual value is a bitset, it can be a combination of the following |
|
|
3913 | values: |
|
|
3914 | |
|
|
3915 | =over 4 |
|
|
3916 | |
|
|
3917 | =item C<1> - faster/larger code |
|
|
3918 | |
|
|
3919 | Use larger code to speed up some operations. |
|
|
3920 | |
|
|
3921 | Currently this is used to override some inlining decisions (enlarging the roughly |
|
|
3922 | 30% code size on amd64. |
|
|
3923 | |
|
|
3924 | When optimising for size, use of compiler flags such as C<-Os> with |
|
|
3925 | gcc recommended, as well as C<-DNDEBUG>, as libev contains a number of |
|
|
3926 | assertions. |
|
|
3927 | |
|
|
3928 | =item C<2> - faster/larger data structures |
|
|
3929 | |
|
|
3930 | Replaces the small 2-heap for timer management by a faster 4-heap, larger |
|
|
3931 | hash table sizes and so on. This will usually further increase codesize |
|
|
3932 | and can additionally have an effect on the size of data structures at |
|
|
3933 | runtime. |
|
|
3934 | |
|
|
3935 | =item C<4> - full API configuration |
|
|
3936 | |
|
|
3937 | This enables priorities (sets C<EV_MAXPRI>=2 and C<EV_MINPRI>=-2), and |
|
|
3938 | enables multiplicity (C<EV_MULTIPLICITY>=1). |
|
|
3939 | |
|
|
3940 | =item C<8> - full API |
|
|
3941 | |
|
|
3942 | This enables a lot of the "lesser used" API functions. See C<ev.h> for |
|
|
3943 | details on which parts of the API are still available without this |
|
|
3944 | feature, and do not complain if this subset changes over time. |
|
|
3945 | |
|
|
3946 | =item C<16> - enable all optional watcher types |
|
|
3947 | |
|
|
3948 | Enables all optional watcher types. If you want to selectively enable |
|
|
3949 | only some watcher types other than I/O and timers (e.g. prepare, |
|
|
3950 | embed, async, child...) you can enable them manually by defining |
|
|
3951 | C<EV_watchertype_ENABLE> to C<1> instead. |
|
|
3952 | |
|
|
3953 | =item C<32> - enable all backends |
|
|
3954 | |
|
|
3955 | This enables all backends - without this feature, you need to enable at |
|
|
3956 | least one backend manually (C<EV_USE_SELECT> is a good choice). |
|
|
3957 | |
|
|
3958 | =item C<64> - enable OS-specific "helper" APIs |
|
|
3959 | |
|
|
3960 | Enable inotify, eventfd, signalfd and similar OS-specific helper APIs by |
|
|
3961 | default. |
|
|
3962 | |
|
|
3963 | =back |
|
|
3964 | |
|
|
3965 | Compiling with C<gcc -Os -DEV_STANDALONE -DEV_USE_EPOLL=1 -DEV_FEATURES=0> |
|
|
3966 | reduces the compiled size of libev from 24.7Kb code/2.8Kb data to 6.5Kb |
|
|
3967 | code/0.3Kb data on my GNU/Linux amd64 system, while still giving you I/O |
|
|
3968 | watchers, timers and monotonic clock support. |
|
|
3969 | |
|
|
3970 | With an intelligent-enough linker (gcc+binutils are intelligent enough |
|
|
3971 | when you use C<-Wl,--gc-sections -ffunction-sections>) functions unused by |
|
|
3972 | your program might be left out as well - a binary starting a timer and an |
|
|
3973 | I/O watcher then might come out at only 5Kb. |
|
|
3974 | |
|
|
3975 | =item EV_AVOID_STDIO |
|
|
3976 | |
|
|
3977 | If this is set to C<1> at compiletime, then libev will avoid using stdio |
|
|
3978 | functions (printf, scanf, perror etc.). This will increase the codesize |
|
|
3979 | somewhat, but if your program doesn't otherwise depend on stdio and your |
|
|
3980 | libc allows it, this avoids linking in the stdio library which is quite |
|
|
3981 | big. |
|
|
3982 | |
|
|
3983 | Note that error messages might become less precise when this option is |
|
|
3984 | enabled. |
|
|
3985 | |
|
|
3986 | =item EV_NSIG |
|
|
3987 | |
|
|
3988 | The highest supported signal number, +1 (or, the number of |
|
|
3989 | signals): Normally, libev tries to deduce the maximum number of signals |
|
|
3990 | automatically, but sometimes this fails, in which case it can be |
|
|
3991 | specified. Also, using a lower number than detected (C<32> should be |
|
|
3992 | good for about any system in existance) can save some memory, as libev |
|
|
3993 | statically allocates some 12-24 bytes per signal number. |
3396 | |
3994 | |
3397 | =item EV_PID_HASHSIZE |
3995 | =item EV_PID_HASHSIZE |
3398 | |
3996 | |
3399 | C<ev_child> watchers use a small hash table to distribute workload by |
3997 | C<ev_child> watchers use a small hash table to distribute workload by |
3400 | pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more |
3998 | pid. The default size is C<16> (or C<1> with C<EV_FEATURES> disabled), |
3401 | than enough. If you need to manage thousands of children you might want to |
3999 | usually more than enough. If you need to manage thousands of children you |
3402 | increase this value (I<must> be a power of two). |
4000 | might want to increase this value (I<must> be a power of two). |
3403 | |
4001 | |
3404 | =item EV_INOTIFY_HASHSIZE |
4002 | =item EV_INOTIFY_HASHSIZE |
3405 | |
4003 | |
3406 | C<ev_stat> watchers use a small hash table to distribute workload by |
4004 | C<ev_stat> watchers use a small hash table to distribute workload by |
3407 | inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>), |
4005 | inotify watch id. The default size is C<16> (or C<1> with C<EV_FEATURES> |
3408 | usually more than enough. If you need to manage thousands of C<ev_stat> |
4006 | disabled), usually more than enough. If you need to manage thousands of |
3409 | watchers you might want to increase this value (I<must> be a power of |
4007 | C<ev_stat> watchers you might want to increase this value (I<must> be a |
3410 | two). |
4008 | power of two). |
3411 | |
4009 | |
3412 | =item EV_USE_4HEAP |
4010 | =item EV_USE_4HEAP |
3413 | |
4011 | |
3414 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
4012 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
3415 | timer and periodics heaps, libev uses a 4-heap when this symbol is defined |
4013 | timer and periodics heaps, libev uses a 4-heap when this symbol is defined |
3416 | to C<1>. The 4-heap uses more complicated (longer) code but has noticeably |
4014 | to C<1>. The 4-heap uses more complicated (longer) code but has noticeably |
3417 | faster performance with many (thousands) of watchers. |
4015 | faster performance with many (thousands) of watchers. |
3418 | |
4016 | |
3419 | The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0> |
4017 | The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it |
3420 | (disabled). |
4018 | will be C<0>. |
3421 | |
4019 | |
3422 | =item EV_HEAP_CACHE_AT |
4020 | =item EV_HEAP_CACHE_AT |
3423 | |
4021 | |
3424 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
4022 | Heaps are not very cache-efficient. To improve the cache-efficiency of the |
3425 | timer and periodics heaps, libev can cache the timestamp (I<at>) within |
4023 | timer and periodics heaps, libev can cache the timestamp (I<at>) within |
3426 | the heap structure (selected by defining C<EV_HEAP_CACHE_AT> to C<1>), |
4024 | the heap structure (selected by defining C<EV_HEAP_CACHE_AT> to C<1>), |
3427 | which uses 8-12 bytes more per watcher and a few hundred bytes more code, |
4025 | which uses 8-12 bytes more per watcher and a few hundred bytes more code, |
3428 | but avoids random read accesses on heap changes. This improves performance |
4026 | but avoids random read accesses on heap changes. This improves performance |
3429 | noticeably with many (hundreds) of watchers. |
4027 | noticeably with many (hundreds) of watchers. |
3430 | |
4028 | |
3431 | The default is C<1> unless C<EV_MINIMAL> is set in which case it is C<0> |
4029 | The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it |
3432 | (disabled). |
4030 | will be C<0>. |
3433 | |
4031 | |
3434 | =item EV_VERIFY |
4032 | =item EV_VERIFY |
3435 | |
4033 | |
3436 | Controls how much internal verification (see C<ev_loop_verify ()>) will |
4034 | Controls how much internal verification (see C<ev_loop_verify ()>) will |
3437 | be done: If set to C<0>, no internal verification code will be compiled |
4035 | be done: If set to C<0>, no internal verification code will be compiled |
… | |
… | |
3439 | called. If set to C<2>, then the internal verification code will be |
4037 | called. If set to C<2>, then the internal verification code will be |
3440 | called once per loop, which can slow down libev. If set to C<3>, then the |
4038 | called once per loop, which can slow down libev. If set to C<3>, then the |
3441 | verification code will be called very frequently, which will slow down |
4039 | verification code will be called very frequently, which will slow down |
3442 | libev considerably. |
4040 | libev considerably. |
3443 | |
4041 | |
3444 | The default is C<1>, unless C<EV_MINIMAL> is set, in which case it will be |
4042 | The default is C<1>, unless C<EV_FEATURES> overrides it, in which case it |
3445 | C<0>. |
4043 | will be C<0>. |
3446 | |
4044 | |
3447 | =item EV_COMMON |
4045 | =item EV_COMMON |
3448 | |
4046 | |
3449 | By default, all watchers have a C<void *data> member. By redefining |
4047 | By default, all watchers have a C<void *data> member. By redefining |
3450 | this macro to a something else you can include more and other types of |
4048 | this macro to a something else you can include more and other types of |
… | |
… | |
3508 | file. |
4106 | file. |
3509 | |
4107 | |
3510 | The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file |
4108 | The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file |
3511 | that everybody includes and which overrides some configure choices: |
4109 | that everybody includes and which overrides some configure choices: |
3512 | |
4110 | |
3513 | #define EV_MINIMAL 1 |
4111 | #define EV_FEATURES 8 |
3514 | #define EV_USE_POLL 0 |
4112 | #define EV_USE_SELECT 1 |
3515 | #define EV_MULTIPLICITY 0 |
|
|
3516 | #define EV_PERIODIC_ENABLE 0 |
4113 | #define EV_PREPARE_ENABLE 1 |
|
|
4114 | #define EV_IDLE_ENABLE 1 |
3517 | #define EV_STAT_ENABLE 0 |
4115 | #define EV_SIGNAL_ENABLE 1 |
3518 | #define EV_FORK_ENABLE 0 |
4116 | #define EV_CHILD_ENABLE 1 |
|
|
4117 | #define EV_USE_STDEXCEPT 0 |
3519 | #define EV_CONFIG_H <config.h> |
4118 | #define EV_CONFIG_H <config.h> |
3520 | #define EV_MINPRI 0 |
|
|
3521 | #define EV_MAXPRI 0 |
|
|
3522 | |
4119 | |
3523 | #include "ev++.h" |
4120 | #include "ev++.h" |
3524 | |
4121 | |
3525 | And a F<ev_cpp.C> implementation file that contains libev proper and is compiled: |
4122 | And a F<ev_cpp.C> implementation file that contains libev proper and is compiled: |
3526 | |
4123 | |
… | |
… | |
3586 | default loop and triggering an C<ev_async> watcher from the default loop |
4183 | default loop and triggering an C<ev_async> watcher from the default loop |
3587 | watcher callback into the event loop interested in the signal. |
4184 | watcher callback into the event loop interested in the signal. |
3588 | |
4185 | |
3589 | =back |
4186 | =back |
3590 | |
4187 | |
|
|
4188 | =head4 THREAD LOCKING EXAMPLE |
|
|
4189 | |
|
|
4190 | Here is a fictitious example of how to run an event loop in a different |
|
|
4191 | thread than where callbacks are being invoked and watchers are |
|
|
4192 | created/added/removed. |
|
|
4193 | |
|
|
4194 | For a real-world example, see the C<EV::Loop::Async> perl module, |
|
|
4195 | which uses exactly this technique (which is suited for many high-level |
|
|
4196 | languages). |
|
|
4197 | |
|
|
4198 | The example uses a pthread mutex to protect the loop data, a condition |
|
|
4199 | variable to wait for callback invocations, an async watcher to notify the |
|
|
4200 | event loop thread and an unspecified mechanism to wake up the main thread. |
|
|
4201 | |
|
|
4202 | First, you need to associate some data with the event loop: |
|
|
4203 | |
|
|
4204 | typedef struct { |
|
|
4205 | mutex_t lock; /* global loop lock */ |
|
|
4206 | ev_async async_w; |
|
|
4207 | thread_t tid; |
|
|
4208 | cond_t invoke_cv; |
|
|
4209 | } userdata; |
|
|
4210 | |
|
|
4211 | void prepare_loop (EV_P) |
|
|
4212 | { |
|
|
4213 | // for simplicity, we use a static userdata struct. |
|
|
4214 | static userdata u; |
|
|
4215 | |
|
|
4216 | ev_async_init (&u->async_w, async_cb); |
|
|
4217 | ev_async_start (EV_A_ &u->async_w); |
|
|
4218 | |
|
|
4219 | pthread_mutex_init (&u->lock, 0); |
|
|
4220 | pthread_cond_init (&u->invoke_cv, 0); |
|
|
4221 | |
|
|
4222 | // now associate this with the loop |
|
|
4223 | ev_set_userdata (EV_A_ u); |
|
|
4224 | ev_set_invoke_pending_cb (EV_A_ l_invoke); |
|
|
4225 | ev_set_loop_release_cb (EV_A_ l_release, l_acquire); |
|
|
4226 | |
|
|
4227 | // then create the thread running ev_loop |
|
|
4228 | pthread_create (&u->tid, 0, l_run, EV_A); |
|
|
4229 | } |
|
|
4230 | |
|
|
4231 | The callback for the C<ev_async> watcher does nothing: the watcher is used |
|
|
4232 | solely to wake up the event loop so it takes notice of any new watchers |
|
|
4233 | that might have been added: |
|
|
4234 | |
|
|
4235 | static void |
|
|
4236 | async_cb (EV_P_ ev_async *w, int revents) |
|
|
4237 | { |
|
|
4238 | // just used for the side effects |
|
|
4239 | } |
|
|
4240 | |
|
|
4241 | The C<l_release> and C<l_acquire> callbacks simply unlock/lock the mutex |
|
|
4242 | protecting the loop data, respectively. |
|
|
4243 | |
|
|
4244 | static void |
|
|
4245 | l_release (EV_P) |
|
|
4246 | { |
|
|
4247 | userdata *u = ev_userdata (EV_A); |
|
|
4248 | pthread_mutex_unlock (&u->lock); |
|
|
4249 | } |
|
|
4250 | |
|
|
4251 | static void |
|
|
4252 | l_acquire (EV_P) |
|
|
4253 | { |
|
|
4254 | userdata *u = ev_userdata (EV_A); |
|
|
4255 | pthread_mutex_lock (&u->lock); |
|
|
4256 | } |
|
|
4257 | |
|
|
4258 | The event loop thread first acquires the mutex, and then jumps straight |
|
|
4259 | into C<ev_loop>: |
|
|
4260 | |
|
|
4261 | void * |
|
|
4262 | l_run (void *thr_arg) |
|
|
4263 | { |
|
|
4264 | struct ev_loop *loop = (struct ev_loop *)thr_arg; |
|
|
4265 | |
|
|
4266 | l_acquire (EV_A); |
|
|
4267 | pthread_setcanceltype (PTHREAD_CANCEL_ASYNCHRONOUS, 0); |
|
|
4268 | ev_loop (EV_A_ 0); |
|
|
4269 | l_release (EV_A); |
|
|
4270 | |
|
|
4271 | return 0; |
|
|
4272 | } |
|
|
4273 | |
|
|
4274 | Instead of invoking all pending watchers, the C<l_invoke> callback will |
|
|
4275 | signal the main thread via some unspecified mechanism (signals? pipe |
|
|
4276 | writes? C<Async::Interrupt>?) and then waits until all pending watchers |
|
|
4277 | have been called (in a while loop because a) spurious wakeups are possible |
|
|
4278 | and b) skipping inter-thread-communication when there are no pending |
|
|
4279 | watchers is very beneficial): |
|
|
4280 | |
|
|
4281 | static void |
|
|
4282 | l_invoke (EV_P) |
|
|
4283 | { |
|
|
4284 | userdata *u = ev_userdata (EV_A); |
|
|
4285 | |
|
|
4286 | while (ev_pending_count (EV_A)) |
|
|
4287 | { |
|
|
4288 | wake_up_other_thread_in_some_magic_or_not_so_magic_way (); |
|
|
4289 | pthread_cond_wait (&u->invoke_cv, &u->lock); |
|
|
4290 | } |
|
|
4291 | } |
|
|
4292 | |
|
|
4293 | Now, whenever the main thread gets told to invoke pending watchers, it |
|
|
4294 | will grab the lock, call C<ev_invoke_pending> and then signal the loop |
|
|
4295 | thread to continue: |
|
|
4296 | |
|
|
4297 | static void |
|
|
4298 | real_invoke_pending (EV_P) |
|
|
4299 | { |
|
|
4300 | userdata *u = ev_userdata (EV_A); |
|
|
4301 | |
|
|
4302 | pthread_mutex_lock (&u->lock); |
|
|
4303 | ev_invoke_pending (EV_A); |
|
|
4304 | pthread_cond_signal (&u->invoke_cv); |
|
|
4305 | pthread_mutex_unlock (&u->lock); |
|
|
4306 | } |
|
|
4307 | |
|
|
4308 | Whenever you want to start/stop a watcher or do other modifications to an |
|
|
4309 | event loop, you will now have to lock: |
|
|
4310 | |
|
|
4311 | ev_timer timeout_watcher; |
|
|
4312 | userdata *u = ev_userdata (EV_A); |
|
|
4313 | |
|
|
4314 | ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.); |
|
|
4315 | |
|
|
4316 | pthread_mutex_lock (&u->lock); |
|
|
4317 | ev_timer_start (EV_A_ &timeout_watcher); |
|
|
4318 | ev_async_send (EV_A_ &u->async_w); |
|
|
4319 | pthread_mutex_unlock (&u->lock); |
|
|
4320 | |
|
|
4321 | Note that sending the C<ev_async> watcher is required because otherwise |
|
|
4322 | an event loop currently blocking in the kernel will have no knowledge |
|
|
4323 | about the newly added timer. By waking up the loop it will pick up any new |
|
|
4324 | watchers in the next event loop iteration. |
|
|
4325 | |
3591 | =head3 COROUTINES |
4326 | =head3 COROUTINES |
3592 | |
4327 | |
3593 | Libev is very accommodating to coroutines ("cooperative threads"): |
4328 | Libev is very accommodating to coroutines ("cooperative threads"): |
3594 | libev fully supports nesting calls to its functions from different |
4329 | libev fully supports nesting calls to its functions from different |
3595 | coroutines (e.g. you can call C<ev_loop> on the same loop from two |
4330 | coroutines (e.g. you can call C<ev_loop> on the same loop from two |
3596 | different coroutines, and switch freely between both coroutines running the |
4331 | different coroutines, and switch freely between both coroutines running |
3597 | loop, as long as you don't confuse yourself). The only exception is that |
4332 | the loop, as long as you don't confuse yourself). The only exception is |
3598 | you must not do this from C<ev_periodic> reschedule callbacks. |
4333 | that you must not do this from C<ev_periodic> reschedule callbacks. |
3599 | |
4334 | |
3600 | Care has been taken to ensure that libev does not keep local state inside |
4335 | Care has been taken to ensure that libev does not keep local state inside |
3601 | C<ev_loop>, and other calls do not usually allow for coroutine switches as |
4336 | C<ev_loop>, and other calls do not usually allow for coroutine switches as |
3602 | they do not call any callbacks. |
4337 | they do not call any callbacks. |
3603 | |
4338 | |
… | |
… | |
3680 | way (note also that glib is the slowest event library known to man). |
4415 | way (note also that glib is the slowest event library known to man). |
3681 | |
4416 | |
3682 | There is no supported compilation method available on windows except |
4417 | There is no supported compilation method available on windows except |
3683 | embedding it into other applications. |
4418 | embedding it into other applications. |
3684 | |
4419 | |
|
|
4420 | Sensible signal handling is officially unsupported by Microsoft - libev |
|
|
4421 | tries its best, but under most conditions, signals will simply not work. |
|
|
4422 | |
3685 | Not a libev limitation but worth mentioning: windows apparently doesn't |
4423 | Not a libev limitation but worth mentioning: windows apparently doesn't |
3686 | accept large writes: instead of resulting in a partial write, windows will |
4424 | accept large writes: instead of resulting in a partial write, windows will |
3687 | either accept everything or return C<ENOBUFS> if the buffer is too large, |
4425 | either accept everything or return C<ENOBUFS> if the buffer is too large, |
3688 | so make sure you only write small amounts into your sockets (less than a |
4426 | so make sure you only write small amounts into your sockets (less than a |
3689 | megabyte seems safe, but this apparently depends on the amount of memory |
4427 | megabyte seems safe, but this apparently depends on the amount of memory |
… | |
… | |
3693 | the abysmal performance of winsockets, using a large number of sockets |
4431 | the abysmal performance of winsockets, using a large number of sockets |
3694 | is not recommended (and not reasonable). If your program needs to use |
4432 | is not recommended (and not reasonable). If your program needs to use |
3695 | more than a hundred or so sockets, then likely it needs to use a totally |
4433 | more than a hundred or so sockets, then likely it needs to use a totally |
3696 | different implementation for windows, as libev offers the POSIX readiness |
4434 | different implementation for windows, as libev offers the POSIX readiness |
3697 | notification model, which cannot be implemented efficiently on windows |
4435 | notification model, which cannot be implemented efficiently on windows |
3698 | (Microsoft monopoly games). |
4436 | (due to Microsoft monopoly games). |
3699 | |
4437 | |
3700 | A typical way to use libev under windows is to embed it (see the embedding |
4438 | A typical way to use libev under windows is to embed it (see the embedding |
3701 | section for details) and use the following F<evwrap.h> header file instead |
4439 | section for details) and use the following F<evwrap.h> header file instead |
3702 | of F<ev.h>: |
4440 | of F<ev.h>: |
3703 | |
4441 | |
… | |
… | |
3739 | |
4477 | |
3740 | Early versions of winsocket's select only supported waiting for a maximum |
4478 | Early versions of winsocket's select only supported waiting for a maximum |
3741 | of C<64> handles (probably owning to the fact that all windows kernels |
4479 | of C<64> handles (probably owning to the fact that all windows kernels |
3742 | can only wait for C<64> things at the same time internally; Microsoft |
4480 | can only wait for C<64> things at the same time internally; Microsoft |
3743 | recommends spawning a chain of threads and wait for 63 handles and the |
4481 | recommends spawning a chain of threads and wait for 63 handles and the |
3744 | previous thread in each. Great). |
4482 | previous thread in each. Sounds great!). |
3745 | |
4483 | |
3746 | Newer versions support more handles, but you need to define C<FD_SETSIZE> |
4484 | Newer versions support more handles, but you need to define C<FD_SETSIZE> |
3747 | to some high number (e.g. C<2048>) before compiling the winsocket select |
4485 | to some high number (e.g. C<2048>) before compiling the winsocket select |
3748 | call (which might be in libev or elsewhere, for example, perl does its own |
4486 | call (which might be in libev or elsewhere, for example, perl and many |
3749 | select emulation on windows). |
4487 | other interpreters do their own select emulation on windows). |
3750 | |
4488 | |
3751 | Another limit is the number of file descriptors in the Microsoft runtime |
4489 | Another limit is the number of file descriptors in the Microsoft runtime |
3752 | libraries, which by default is C<64> (there must be a hidden I<64> fetish |
4490 | libraries, which by default is C<64> (there must be a hidden I<64> |
3753 | or something like this inside Microsoft). You can increase this by calling |
4491 | fetish or something like this inside Microsoft). You can increase this |
3754 | C<_setmaxstdio>, which can increase this limit to C<2048> (another |
4492 | by calling C<_setmaxstdio>, which can increase this limit to C<2048> |
3755 | arbitrary limit), but is broken in many versions of the Microsoft runtime |
4493 | (another arbitrary limit), but is broken in many versions of the Microsoft |
3756 | libraries. |
|
|
3757 | |
|
|
3758 | This might get you to about C<512> or C<2048> sockets (depending on |
4494 | runtime libraries. This might get you to about C<512> or C<2048> sockets |
3759 | windows version and/or the phase of the moon). To get more, you need to |
4495 | (depending on windows version and/or the phase of the moon). To get more, |
3760 | wrap all I/O functions and provide your own fd management, but the cost of |
4496 | you need to wrap all I/O functions and provide your own fd management, but |
3761 | calling select (O(n²)) will likely make this unworkable. |
4497 | the cost of calling select (O(n²)) will likely make this unworkable. |
3762 | |
4498 | |
3763 | =back |
4499 | =back |
3764 | |
4500 | |
3765 | =head2 PORTABILITY REQUIREMENTS |
4501 | =head2 PORTABILITY REQUIREMENTS |
3766 | |
4502 | |
… | |
… | |
3809 | =item C<double> must hold a time value in seconds with enough accuracy |
4545 | =item C<double> must hold a time value in seconds with enough accuracy |
3810 | |
4546 | |
3811 | The type C<double> is used to represent timestamps. It is required to |
4547 | The type C<double> is used to represent timestamps. It is required to |
3812 | have at least 51 bits of mantissa (and 9 bits of exponent), which is good |
4548 | have at least 51 bits of mantissa (and 9 bits of exponent), which is good |
3813 | enough for at least into the year 4000. This requirement is fulfilled by |
4549 | enough for at least into the year 4000. This requirement is fulfilled by |
3814 | implementations implementing IEEE 754 (basically all existing ones). |
4550 | implementations implementing IEEE 754, which is basically all existing |
|
|
4551 | ones. With IEEE 754 doubles, you get microsecond accuracy until at least |
|
|
4552 | 2200. |
3815 | |
4553 | |
3816 | =back |
4554 | =back |
3817 | |
4555 | |
3818 | If you know of other additional requirements drop me a note. |
4556 | If you know of other additional requirements drop me a note. |
3819 | |
4557 | |
… | |
… | |
3887 | involves iterating over all running async watchers or all signal numbers. |
4625 | involves iterating over all running async watchers or all signal numbers. |
3888 | |
4626 | |
3889 | =back |
4627 | =back |
3890 | |
4628 | |
3891 | |
4629 | |
|
|
4630 | =head1 PORTING FROM LIBEV 3.X TO 4.X |
|
|
4631 | |
|
|
4632 | The major version 4 introduced some minor incompatible changes to the API. |
|
|
4633 | |
|
|
4634 | At the moment, the C<ev.h> header file tries to implement superficial |
|
|
4635 | compatibility, so most programs should still compile. Those might be |
|
|
4636 | removed in later versions of libev, so better update early than late. |
|
|
4637 | |
|
|
4638 | =over 4 |
|
|
4639 | |
|
|
4640 | =item C<ev_loop_count> renamed to C<ev_iteration> |
|
|
4641 | |
|
|
4642 | =item C<ev_loop_depth> renamed to C<ev_depth> |
|
|
4643 | |
|
|
4644 | =item C<ev_loop_verify> renamed to C<ev_verify> |
|
|
4645 | |
|
|
4646 | Most functions working on C<struct ev_loop> objects don't have an |
|
|
4647 | C<ev_loop_> prefix, so it was removed. Note that C<ev_loop_fork> is |
|
|
4648 | still called C<ev_loop_fork> because it would otherwise clash with the |
|
|
4649 | C<ev_fork> typedef. |
|
|
4650 | |
|
|
4651 | =item C<EV_TIMEOUT> renamed to C<EV_TIMER> in C<revents> |
|
|
4652 | |
|
|
4653 | This is a simple rename - all other watcher types use their name |
|
|
4654 | as revents flag, and now C<ev_timer> does, too. |
|
|
4655 | |
|
|
4656 | Both C<EV_TIMER> and C<EV_TIMEOUT> symbols were present in 3.x versions |
|
|
4657 | and continue to be present for the forseeable future, so this is mostly a |
|
|
4658 | documentation change. |
|
|
4659 | |
|
|
4660 | =item C<EV_MINIMAL> mechanism replaced by C<EV_FEATURES> |
|
|
4661 | |
|
|
4662 | The preprocessor symbol C<EV_MINIMAL> has been replaced by a different |
|
|
4663 | mechanism, C<EV_FEATURES>. Programs using C<EV_MINIMAL> usually compile |
|
|
4664 | and work, but the library code will of course be larger. |
|
|
4665 | |
|
|
4666 | =back |
|
|
4667 | |
|
|
4668 | |
|
|
4669 | =head1 GLOSSARY |
|
|
4670 | |
|
|
4671 | =over 4 |
|
|
4672 | |
|
|
4673 | =item active |
|
|
4674 | |
|
|
4675 | A watcher is active as long as it has been started (has been attached to |
|
|
4676 | an event loop) but not yet stopped (disassociated from the event loop). |
|
|
4677 | |
|
|
4678 | =item application |
|
|
4679 | |
|
|
4680 | In this document, an application is whatever is using libev. |
|
|
4681 | |
|
|
4682 | =item callback |
|
|
4683 | |
|
|
4684 | The address of a function that is called when some event has been |
|
|
4685 | detected. Callbacks are being passed the event loop, the watcher that |
|
|
4686 | received the event, and the actual event bitset. |
|
|
4687 | |
|
|
4688 | =item callback invocation |
|
|
4689 | |
|
|
4690 | The act of calling the callback associated with a watcher. |
|
|
4691 | |
|
|
4692 | =item event |
|
|
4693 | |
|
|
4694 | A change of state of some external event, such as data now being available |
|
|
4695 | for reading on a file descriptor, time having passed or simply not having |
|
|
4696 | any other events happening anymore. |
|
|
4697 | |
|
|
4698 | In libev, events are represented as single bits (such as C<EV_READ> or |
|
|
4699 | C<EV_TIMER>). |
|
|
4700 | |
|
|
4701 | =item event library |
|
|
4702 | |
|
|
4703 | A software package implementing an event model and loop. |
|
|
4704 | |
|
|
4705 | =item event loop |
|
|
4706 | |
|
|
4707 | An entity that handles and processes external events and converts them |
|
|
4708 | into callback invocations. |
|
|
4709 | |
|
|
4710 | =item event model |
|
|
4711 | |
|
|
4712 | The model used to describe how an event loop handles and processes |
|
|
4713 | watchers and events. |
|
|
4714 | |
|
|
4715 | =item pending |
|
|
4716 | |
|
|
4717 | A watcher is pending as soon as the corresponding event has been detected, |
|
|
4718 | and stops being pending as soon as the watcher will be invoked or its |
|
|
4719 | pending status is explicitly cleared by the application. |
|
|
4720 | |
|
|
4721 | A watcher can be pending, but not active. Stopping a watcher also clears |
|
|
4722 | its pending status. |
|
|
4723 | |
|
|
4724 | =item real time |
|
|
4725 | |
|
|
4726 | The physical time that is observed. It is apparently strictly monotonic :) |
|
|
4727 | |
|
|
4728 | =item wall-clock time |
|
|
4729 | |
|
|
4730 | The time and date as shown on clocks. Unlike real time, it can actually |
|
|
4731 | be wrong and jump forwards and backwards, e.g. when the you adjust your |
|
|
4732 | clock. |
|
|
4733 | |
|
|
4734 | =item watcher |
|
|
4735 | |
|
|
4736 | A data structure that describes interest in certain events. Watchers need |
|
|
4737 | to be started (attached to an event loop) before they can receive events. |
|
|
4738 | |
|
|
4739 | =item watcher invocation |
|
|
4740 | |
|
|
4741 | The act of calling the callback associated with a watcher. |
|
|
4742 | |
|
|
4743 | =back |
|
|
4744 | |
3892 | =head1 AUTHOR |
4745 | =head1 AUTHOR |
3893 | |
4746 | |
3894 | Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael Magnusson. |
4747 | Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael Magnusson. |
3895 | |
4748 | |