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2 | |
2 | |
3 | libev - a high performance full-featured event loop written in C |
3 | libev - a high performance full-featured event loop written in C |
4 | |
4 | |
5 | =head1 SYNOPSIS |
5 | =head1 SYNOPSIS |
6 | |
6 | |
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7 | /* this is the only header you need */ |
7 | #include <ev.h> |
8 | #include <ev.h> |
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9 | |
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10 | /* what follows is a fully working example program */ |
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11 | ev_io stdin_watcher; |
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12 | ev_timer timeout_watcher; |
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13 | |
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14 | /* called when data readable on stdin */ |
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15 | static void |
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16 | stdin_cb (EV_P_ struct ev_io *w, int revents) |
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17 | { |
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18 | /* puts ("stdin ready"); */ |
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19 | ev_io_stop (EV_A_ w); /* just a syntax example */ |
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20 | ev_unloop (EV_A_ EVUNLOOP_ALL); /* leave all loop calls */ |
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21 | } |
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22 | |
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23 | static void |
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24 | timeout_cb (EV_P_ struct ev_timer *w, int revents) |
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25 | { |
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26 | /* puts ("timeout"); */ |
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27 | ev_unloop (EV_A_ EVUNLOOP_ONE); /* leave one loop call */ |
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28 | } |
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29 | |
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30 | int |
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31 | main (void) |
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32 | { |
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33 | struct ev_loop *loop = ev_default_loop (0); |
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34 | |
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35 | /* initialise an io watcher, then start it */ |
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36 | ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ); |
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37 | ev_io_start (loop, &stdin_watcher); |
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38 | |
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39 | /* simple non-repeating 5.5 second timeout */ |
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40 | ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.); |
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41 | ev_timer_start (loop, &timeout_watcher); |
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42 | |
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43 | /* loop till timeout or data ready */ |
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44 | ev_loop (loop, 0); |
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45 | |
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46 | return 0; |
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47 | } |
8 | |
48 | |
9 | =head1 DESCRIPTION |
49 | =head1 DESCRIPTION |
10 | |
50 | |
11 | Libev is an event loop: you register interest in certain events (such as a |
51 | Libev is an event loop: you register interest in certain events (such as a |
12 | file descriptor being readable or a timeout occuring), and it will manage |
52 | file descriptor being readable or a timeout occuring), and it will manage |
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48 | the beginning of 1970, details are complicated, don't ask). This type is |
88 | the beginning of 1970, details are complicated, don't ask). This type is |
49 | called C<ev_tstamp>, which is what you should use too. It usually aliases |
89 | called C<ev_tstamp>, which is what you should use too. It usually aliases |
50 | to the C<double> type in C, and when you need to do any calculations on |
90 | to the C<double> type in C, and when you need to do any calculations on |
51 | it, you should treat it as such. |
91 | it, you should treat it as such. |
52 | |
92 | |
53 | |
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54 | =head1 GLOBAL FUNCTIONS |
93 | =head1 GLOBAL FUNCTIONS |
55 | |
94 | |
56 | These functions can be called anytime, even before initialising the |
95 | These functions can be called anytime, even before initialising the |
57 | library in any way. |
96 | library in any way. |
58 | |
97 | |
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116 | C<ev_embeddable_backends () & ev_supported_backends ()>, likewise for |
155 | C<ev_embeddable_backends () & ev_supported_backends ()>, likewise for |
117 | recommended ones. |
156 | recommended ones. |
118 | |
157 | |
119 | See the description of C<ev_embed> watchers for more info. |
158 | See the description of C<ev_embed> watchers for more info. |
120 | |
159 | |
121 | =item ev_set_allocator (void *(*cb)(void *ptr, long size)) |
160 | =item ev_set_allocator (void *(*cb)(void *ptr, size_t size)) |
122 | |
161 | |
123 | Sets the allocation function to use (the prototype is similar to the |
162 | Sets the allocation function to use (the prototype and semantics are |
124 | realloc C function, the semantics are identical). It is used to allocate |
163 | identical to the realloc C function). It is used to allocate and free |
125 | and free memory (no surprises here). If it returns zero when memory |
164 | memory (no surprises here). If it returns zero when memory needs to be |
126 | needs to be allocated, the library might abort or take some potentially |
165 | allocated, the library might abort or take some potentially destructive |
127 | destructive action. The default is your system realloc function. |
166 | action. The default is your system realloc function. |
128 | |
167 | |
129 | You could override this function in high-availability programs to, say, |
168 | You could override this function in high-availability programs to, say, |
130 | free some memory if it cannot allocate memory, to use a special allocator, |
169 | free some memory if it cannot allocate memory, to use a special allocator, |
131 | or even to sleep a while and retry until some memory is available. |
170 | or even to sleep a while and retry until some memory is available. |
132 | |
171 | |
133 | Example: replace the libev allocator with one that waits a bit and then |
172 | Example: replace the libev allocator with one that waits a bit and then |
134 | retries: better than mine). |
173 | retries: better than mine). |
135 | |
174 | |
136 | static void * |
175 | static void * |
137 | persistent_realloc (void *ptr, long size) |
176 | persistent_realloc (void *ptr, size_t size) |
138 | { |
177 | { |
139 | for (;;) |
178 | for (;;) |
140 | { |
179 | { |
141 | void *newptr = realloc (ptr, size); |
180 | void *newptr = realloc (ptr, size); |
142 | |
181 | |
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468 | ev_ref (myloop); |
507 | ev_ref (myloop); |
469 | ev_signal_stop (myloop, &exitsig); |
508 | ev_signal_stop (myloop, &exitsig); |
470 | |
509 | |
471 | =back |
510 | =back |
472 | |
511 | |
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512 | |
473 | =head1 ANATOMY OF A WATCHER |
513 | =head1 ANATOMY OF A WATCHER |
474 | |
514 | |
475 | A watcher is a structure that you create and register to record your |
515 | A watcher is a structure that you create and register to record your |
476 | interest in some event. For instance, if you want to wait for STDIN to |
516 | interest in some event. For instance, if you want to wait for STDIN to |
477 | become readable, you would create an C<ev_io> watcher for that: |
517 | become readable, you would create an C<ev_io> watcher for that: |
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543 | The signal specified in the C<ev_signal> watcher has been received by a thread. |
583 | The signal specified in the C<ev_signal> watcher has been received by a thread. |
544 | |
584 | |
545 | =item C<EV_CHILD> |
585 | =item C<EV_CHILD> |
546 | |
586 | |
547 | The pid specified in the C<ev_child> watcher has received a status change. |
587 | The pid specified in the C<ev_child> watcher has received a status change. |
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588 | |
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589 | =item C<EV_STAT> |
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590 | |
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591 | The path specified in the C<ev_stat> watcher changed its attributes somehow. |
548 | |
592 | |
549 | =item C<EV_IDLE> |
593 | =item C<EV_IDLE> |
550 | |
594 | |
551 | The C<ev_idle> watcher has determined that you have nothing better to do. |
595 | The C<ev_idle> watcher has determined that you have nothing better to do. |
552 | |
596 | |
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560 | received events. Callbacks of both watcher types can start and stop as |
604 | received events. Callbacks of both watcher types can start and stop as |
561 | many watchers as they want, and all of them will be taken into account |
605 | many watchers as they want, and all of them will be taken into account |
562 | (for example, a C<ev_prepare> watcher might start an idle watcher to keep |
606 | (for example, a C<ev_prepare> watcher might start an idle watcher to keep |
563 | C<ev_loop> from blocking). |
607 | C<ev_loop> from blocking). |
564 | |
608 | |
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609 | =item C<EV_EMBED> |
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610 | |
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611 | The embedded event loop specified in the C<ev_embed> watcher needs attention. |
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612 | |
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613 | =item C<EV_FORK> |
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614 | |
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615 | The event loop has been resumed in the child process after fork (see |
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616 | C<ev_fork>). |
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617 | |
565 | =item C<EV_ERROR> |
618 | =item C<EV_ERROR> |
566 | |
619 | |
567 | An unspecified error has occured, the watcher has been stopped. This might |
620 | An unspecified error has occured, the watcher has been stopped. This might |
568 | happen because the watcher could not be properly started because libev |
621 | happen because the watcher could not be properly started because libev |
569 | ran out of memory, a file descriptor was found to be closed or any other |
622 | ran out of memory, a file descriptor was found to be closed or any other |
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576 | with the error from read() or write(). This will not work in multithreaded |
629 | with the error from read() or write(). This will not work in multithreaded |
577 | programs, though, so beware. |
630 | programs, though, so beware. |
578 | |
631 | |
579 | =back |
632 | =back |
580 | |
633 | |
581 | =head2 SUMMARY OF GENERIC WATCHER FUNCTIONS |
634 | =head2 GENERIC WATCHER FUNCTIONS |
582 | |
635 | |
583 | In the following description, C<TYPE> stands for the watcher type, |
636 | In the following description, C<TYPE> stands for the watcher type, |
584 | e.g. C<timer> for C<ev_timer> watchers and C<io> for C<ev_io> watchers. |
637 | e.g. C<timer> for C<ev_timer> watchers and C<io> for C<ev_io> watchers. |
585 | |
638 | |
586 | =over 4 |
639 | =over 4 |
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595 | which rolls both calls into one. |
648 | which rolls both calls into one. |
596 | |
649 | |
597 | You can reinitialise a watcher at any time as long as it has been stopped |
650 | You can reinitialise a watcher at any time as long as it has been stopped |
598 | (or never started) and there are no pending events outstanding. |
651 | (or never started) and there are no pending events outstanding. |
599 | |
652 | |
600 | The callbakc is always of type C<void (*)(ev_loop *loop, ev_TYPE *watcher, |
653 | The callback is always of type C<void (*)(ev_loop *loop, ev_TYPE *watcher, |
601 | int revents)>. |
654 | int revents)>. |
602 | |
655 | |
603 | =item C<ev_TYPE_set> (ev_TYPE *, [args]) |
656 | =item C<ev_TYPE_set> (ev_TYPE *, [args]) |
604 | |
657 | |
605 | This macro initialises the type-specific parts of a watcher. You need to |
658 | This macro initialises the type-specific parts of a watcher. You need to |
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688 | |
741 | |
689 | |
742 | |
690 | =head1 WATCHER TYPES |
743 | =head1 WATCHER TYPES |
691 | |
744 | |
692 | This section describes each watcher in detail, but will not repeat |
745 | This section describes each watcher in detail, but will not repeat |
693 | information given in the last section. |
746 | information given in the last section. Any initialisation/set macros, |
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747 | functions and members specific to the watcher type are explained. |
694 | |
748 | |
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749 | Members are additionally marked with either I<[read-only]>, meaning that, |
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750 | while the watcher is active, you can look at the member and expect some |
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751 | sensible content, but you must not modify it (you can modify it while the |
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752 | watcher is stopped to your hearts content), or I<[read-write]>, which |
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753 | means you can expect it to have some sensible content while the watcher |
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754 | is active, but you can also modify it. Modifying it may not do something |
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755 | sensible or take immediate effect (or do anything at all), but libev will |
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756 | not crash or malfunction in any way. |
695 | |
757 | |
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758 | |
696 | =head2 C<ev_io> - is this file descriptor readable or writable |
759 | =head2 C<ev_io> - is this file descriptor readable or writable? |
697 | |
760 | |
698 | I/O watchers check whether a file descriptor is readable or writable |
761 | I/O watchers check whether a file descriptor is readable or writable |
699 | in each iteration of the event loop (This behaviour is called |
762 | in each iteration of the event loop, or, more precisely, when reading |
700 | level-triggering because you keep receiving events as long as the |
763 | would not block the process and writing would at least be able to write |
701 | condition persists. Remember you can stop the watcher if you don't want to |
764 | some data. This behaviour is called level-triggering because you keep |
702 | act on the event and neither want to receive future events). |
765 | receiving events as long as the condition persists. Remember you can stop |
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766 | the watcher if you don't want to act on the event and neither want to |
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767 | receive future events. |
703 | |
768 | |
704 | In general you can register as many read and/or write event watchers per |
769 | In general you can register as many read and/or write event watchers per |
705 | fd as you want (as long as you don't confuse yourself). Setting all file |
770 | fd as you want (as long as you don't confuse yourself). Setting all file |
706 | descriptors to non-blocking mode is also usually a good idea (but not |
771 | descriptors to non-blocking mode is also usually a good idea (but not |
707 | required if you know what you are doing). |
772 | required if you know what you are doing). |
708 | |
773 | |
709 | You have to be careful with dup'ed file descriptors, though. Some backends |
774 | You have to be careful with dup'ed file descriptors, though. Some backends |
710 | (the linux epoll backend is a notable example) cannot handle dup'ed file |
775 | (the linux epoll backend is a notable example) cannot handle dup'ed file |
711 | descriptors correctly if you register interest in two or more fds pointing |
776 | descriptors correctly if you register interest in two or more fds pointing |
712 | to the same underlying file/socket etc. description (that is, they share |
777 | to the same underlying file/socket/etc. description (that is, they share |
713 | the same underlying "file open"). |
778 | the same underlying "file open"). |
714 | |
779 | |
715 | If you must do this, then force the use of a known-to-be-good backend |
780 | If you must do this, then force the use of a known-to-be-good backend |
716 | (at the time of this writing, this includes only C<EVBACKEND_SELECT> and |
781 | (at the time of this writing, this includes only C<EVBACKEND_SELECT> and |
717 | C<EVBACKEND_POLL>). |
782 | C<EVBACKEND_POLL>). |
718 | |
783 | |
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784 | Another thing you have to watch out for is that it is quite easy to |
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785 | receive "spurious" readyness notifications, that is your callback might |
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786 | be called with C<EV_READ> but a subsequent C<read>(2) will actually block |
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787 | because there is no data. Not only are some backends known to create a |
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788 | lot of those (for example solaris ports), it is very easy to get into |
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789 | this situation even with a relatively standard program structure. Thus |
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790 | it is best to always use non-blocking I/O: An extra C<read>(2) returning |
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791 | C<EAGAIN> is far preferable to a program hanging until some data arrives. |
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792 | |
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793 | If you cannot run the fd in non-blocking mode (for example you should not |
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794 | play around with an Xlib connection), then you have to seperately re-test |
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795 | wether a file descriptor is really ready with a known-to-be good interface |
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796 | such as poll (fortunately in our Xlib example, Xlib already does this on |
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797 | its own, so its quite safe to use). |
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798 | |
719 | =over 4 |
799 | =over 4 |
720 | |
800 | |
721 | =item ev_io_init (ev_io *, callback, int fd, int events) |
801 | =item ev_io_init (ev_io *, callback, int fd, int events) |
722 | |
802 | |
723 | =item ev_io_set (ev_io *, int fd, int events) |
803 | =item ev_io_set (ev_io *, int fd, int events) |
724 | |
804 | |
725 | Configures an C<ev_io> watcher. The fd is the file descriptor to rceeive |
805 | Configures an C<ev_io> watcher. The C<fd> is the file descriptor to |
726 | events for and events is either C<EV_READ>, C<EV_WRITE> or C<EV_READ | |
806 | rceeive events for and events is either C<EV_READ>, C<EV_WRITE> or |
727 | EV_WRITE> to receive the given events. |
807 | C<EV_READ | EV_WRITE> to receive the given events. |
728 | |
808 | |
729 | Please note that most of the more scalable backend mechanisms (for example |
809 | =item int fd [read-only] |
730 | epoll and solaris ports) can result in spurious readyness notifications |
810 | |
731 | for file descriptors, so you practically need to use non-blocking I/O (and |
811 | The file descriptor being watched. |
732 | treat callback invocation as hint only), or retest separately with a safe |
812 | |
733 | interface before doing I/O (XLib can do this), or force the use of either |
813 | =item int events [read-only] |
734 | C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>, which don't suffer from this |
814 | |
735 | problem. Also note that it is quite easy to have your callback invoked |
815 | The events being watched. |
736 | when the readyness condition is no longer valid even when employing |
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737 | typical ways of handling events, so its a good idea to use non-blocking |
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738 | I/O unconditionally. |
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739 | |
816 | |
740 | =back |
817 | =back |
741 | |
818 | |
742 | Example: call C<stdin_readable_cb> when STDIN_FILENO has become, well |
819 | Example: call C<stdin_readable_cb> when STDIN_FILENO has become, well |
743 | readable, but only once. Since it is likely line-buffered, you could |
820 | readable, but only once. Since it is likely line-buffered, you could |
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756 | ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ); |
833 | ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ); |
757 | ev_io_start (loop, &stdin_readable); |
834 | ev_io_start (loop, &stdin_readable); |
758 | ev_loop (loop, 0); |
835 | ev_loop (loop, 0); |
759 | |
836 | |
760 | |
837 | |
761 | =head2 C<ev_timer> - relative and optionally recurring timeouts |
838 | =head2 C<ev_timer> - relative and optionally repeating timeouts |
762 | |
839 | |
763 | Timer watchers are simple relative timers that generate an event after a |
840 | Timer watchers are simple relative timers that generate an event after a |
764 | given time, and optionally repeating in regular intervals after that. |
841 | given time, and optionally repeating in regular intervals after that. |
765 | |
842 | |
766 | The timers are based on real time, that is, if you register an event that |
843 | The timers are based on real time, that is, if you register an event that |
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807 | |
884 | |
808 | If the timer is repeating, either start it if necessary (with the repeat |
885 | If the timer is repeating, either start it if necessary (with the repeat |
809 | value), or reset the running timer to the repeat value. |
886 | value), or reset the running timer to the repeat value. |
810 | |
887 | |
811 | This sounds a bit complicated, but here is a useful and typical |
888 | This sounds a bit complicated, but here is a useful and typical |
812 | example: Imagine you have a tcp connection and you want a so-called idle |
889 | example: Imagine you have a tcp connection and you want a so-called |
813 | timeout, that is, you want to be called when there have been, say, 60 |
890 | idle timeout, that is, you want to be called when there have been, |
814 | seconds of inactivity on the socket. The easiest way to do this is to |
891 | say, 60 seconds of inactivity on the socket. The easiest way to do |
815 | configure an C<ev_timer> with after=repeat=60 and calling ev_timer_again each |
892 | this is to configure an C<ev_timer> with C<after>=C<repeat>=C<60> and calling |
816 | time you successfully read or write some data. If you go into an idle |
893 | C<ev_timer_again> each time you successfully read or write some data. If |
817 | state where you do not expect data to travel on the socket, you can stop |
894 | you go into an idle state where you do not expect data to travel on the |
818 | the timer, and again will automatically restart it if need be. |
895 | socket, you can stop the timer, and again will automatically restart it if |
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896 | need be. |
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897 | |
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898 | You can also ignore the C<after> value and C<ev_timer_start> altogether |
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899 | and only ever use the C<repeat> value: |
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900 | |
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901 | ev_timer_init (timer, callback, 0., 5.); |
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902 | ev_timer_again (loop, timer); |
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903 | ... |
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904 | timer->again = 17.; |
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905 | ev_timer_again (loop, timer); |
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906 | ... |
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907 | timer->again = 10.; |
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908 | ev_timer_again (loop, timer); |
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909 | |
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910 | This is more efficient then stopping/starting the timer eahc time you want |
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911 | to modify its timeout value. |
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912 | |
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913 | =item ev_tstamp repeat [read-write] |
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914 | |
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915 | The current C<repeat> value. Will be used each time the watcher times out |
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916 | or C<ev_timer_again> is called and determines the next timeout (if any), |
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917 | which is also when any modifications are taken into account. |
819 | |
918 | |
820 | =back |
919 | =back |
821 | |
920 | |
822 | Example: create a timer that fires after 60 seconds. |
921 | Example: create a timer that fires after 60 seconds. |
823 | |
922 | |
… | |
… | |
848 | // and in some piece of code that gets executed on any "activity": |
947 | // and in some piece of code that gets executed on any "activity": |
849 | // reset the timeout to start ticking again at 10 seconds |
948 | // reset the timeout to start ticking again at 10 seconds |
850 | ev_timer_again (&mytimer); |
949 | ev_timer_again (&mytimer); |
851 | |
950 | |
852 | |
951 | |
853 | =head2 C<ev_periodic> - to cron or not to cron |
952 | =head2 C<ev_periodic> - to cron or not to cron? |
854 | |
953 | |
855 | Periodic watchers are also timers of a kind, but they are very versatile |
954 | Periodic watchers are also timers of a kind, but they are very versatile |
856 | (and unfortunately a bit complex). |
955 | (and unfortunately a bit complex). |
857 | |
956 | |
858 | Unlike C<ev_timer>'s, they are not based on real time (or relative time) |
957 | Unlike C<ev_timer>'s, they are not based on real time (or relative time) |
859 | but on wallclock time (absolute time). You can tell a periodic watcher |
958 | but on wallclock time (absolute time). You can tell a periodic watcher |
860 | to trigger "at" some specific point in time. For example, if you tell a |
959 | to trigger "at" some specific point in time. For example, if you tell a |
861 | periodic watcher to trigger in 10 seconds (by specifiying e.g. c<ev_now () |
960 | periodic watcher to trigger in 10 seconds (by specifiying e.g. C<ev_now () |
862 | + 10.>) and then reset your system clock to the last year, then it will |
961 | + 10.>) and then reset your system clock to the last year, then it will |
863 | take a year to trigger the event (unlike an C<ev_timer>, which would trigger |
962 | take a year to trigger the event (unlike an C<ev_timer>, which would trigger |
864 | roughly 10 seconds later and of course not if you reset your system time |
963 | roughly 10 seconds later and of course not if you reset your system time |
865 | again). |
964 | again). |
866 | |
965 | |
… | |
… | |
950 | Simply stops and restarts the periodic watcher again. This is only useful |
1049 | Simply stops and restarts the periodic watcher again. This is only useful |
951 | when you changed some parameters or the reschedule callback would return |
1050 | when you changed some parameters or the reschedule callback would return |
952 | a different time than the last time it was called (e.g. in a crond like |
1051 | a different time than the last time it was called (e.g. in a crond like |
953 | program when the crontabs have changed). |
1052 | program when the crontabs have changed). |
954 | |
1053 | |
|
|
1054 | =item ev_tstamp interval [read-write] |
|
|
1055 | |
|
|
1056 | The current interval value. Can be modified any time, but changes only |
|
|
1057 | take effect when the periodic timer fires or C<ev_periodic_again> is being |
|
|
1058 | called. |
|
|
1059 | |
|
|
1060 | =item ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read-write] |
|
|
1061 | |
|
|
1062 | The current reschedule callback, or C<0>, if this functionality is |
|
|
1063 | switched off. Can be changed any time, but changes only take effect when |
|
|
1064 | the periodic timer fires or C<ev_periodic_again> is being called. |
|
|
1065 | |
955 | =back |
1066 | =back |
956 | |
1067 | |
957 | Example: call a callback every hour, or, more precisely, whenever the |
1068 | Example: call a callback every hour, or, more precisely, whenever the |
958 | system clock is divisible by 3600. The callback invocation times have |
1069 | system clock is divisible by 3600. The callback invocation times have |
959 | potentially a lot of jittering, but good long-term stability. |
1070 | potentially a lot of jittering, but good long-term stability. |
… | |
… | |
986 | ev_periodic_init (&hourly_tick, clock_cb, |
1097 | ev_periodic_init (&hourly_tick, clock_cb, |
987 | fmod (ev_now (loop), 3600.), 3600., 0); |
1098 | fmod (ev_now (loop), 3600.), 3600., 0); |
988 | ev_periodic_start (loop, &hourly_tick); |
1099 | ev_periodic_start (loop, &hourly_tick); |
989 | |
1100 | |
990 | |
1101 | |
991 | =head2 C<ev_signal> - signal me when a signal gets signalled |
1102 | =head2 C<ev_signal> - signal me when a signal gets signalled! |
992 | |
1103 | |
993 | Signal watchers will trigger an event when the process receives a specific |
1104 | Signal watchers will trigger an event when the process receives a specific |
994 | signal one or more times. Even though signals are very asynchronous, libev |
1105 | signal one or more times. Even though signals are very asynchronous, libev |
995 | will try it's best to deliver signals synchronously, i.e. as part of the |
1106 | will try it's best to deliver signals synchronously, i.e. as part of the |
996 | normal event processing, like any other event. |
1107 | normal event processing, like any other event. |
… | |
… | |
1009 | =item ev_signal_set (ev_signal *, int signum) |
1120 | =item ev_signal_set (ev_signal *, int signum) |
1010 | |
1121 | |
1011 | Configures the watcher to trigger on the given signal number (usually one |
1122 | Configures the watcher to trigger on the given signal number (usually one |
1012 | of the C<SIGxxx> constants). |
1123 | of the C<SIGxxx> constants). |
1013 | |
1124 | |
|
|
1125 | =item int signum [read-only] |
|
|
1126 | |
|
|
1127 | The signal the watcher watches out for. |
|
|
1128 | |
1014 | =back |
1129 | =back |
1015 | |
1130 | |
1016 | |
1131 | |
1017 | =head2 C<ev_child> - wait for pid status changes |
1132 | =head2 C<ev_child> - watch out for process status changes |
1018 | |
1133 | |
1019 | Child watchers trigger when your process receives a SIGCHLD in response to |
1134 | Child watchers trigger when your process receives a SIGCHLD in response to |
1020 | some child status changes (most typically when a child of yours dies). |
1135 | some child status changes (most typically when a child of yours dies). |
1021 | |
1136 | |
1022 | =over 4 |
1137 | =over 4 |
… | |
… | |
1030 | at the C<rstatus> member of the C<ev_child> watcher structure to see |
1145 | at the C<rstatus> member of the C<ev_child> watcher structure to see |
1031 | the status word (use the macros from C<sys/wait.h> and see your systems |
1146 | the status word (use the macros from C<sys/wait.h> and see your systems |
1032 | C<waitpid> documentation). The C<rpid> member contains the pid of the |
1147 | C<waitpid> documentation). The C<rpid> member contains the pid of the |
1033 | process causing the status change. |
1148 | process causing the status change. |
1034 | |
1149 | |
|
|
1150 | =item int pid [read-only] |
|
|
1151 | |
|
|
1152 | The process id this watcher watches out for, or C<0>, meaning any process id. |
|
|
1153 | |
|
|
1154 | =item int rpid [read-write] |
|
|
1155 | |
|
|
1156 | The process id that detected a status change. |
|
|
1157 | |
|
|
1158 | =item int rstatus [read-write] |
|
|
1159 | |
|
|
1160 | The process exit/trace status caused by C<rpid> (see your systems |
|
|
1161 | C<waitpid> and C<sys/wait.h> documentation for details). |
|
|
1162 | |
1035 | =back |
1163 | =back |
1036 | |
1164 | |
1037 | Example: try to exit cleanly on SIGINT and SIGTERM. |
1165 | Example: try to exit cleanly on SIGINT and SIGTERM. |
1038 | |
1166 | |
1039 | static void |
1167 | static void |
… | |
… | |
1045 | struct ev_signal signal_watcher; |
1173 | struct ev_signal signal_watcher; |
1046 | ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
1174 | ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
1047 | ev_signal_start (loop, &sigint_cb); |
1175 | ev_signal_start (loop, &sigint_cb); |
1048 | |
1176 | |
1049 | |
1177 | |
|
|
1178 | =head2 C<ev_stat> - did the file attributes just change? |
|
|
1179 | |
|
|
1180 | This watches a filesystem path for attribute changes. That is, it calls |
|
|
1181 | C<stat> regularly (or when the OS says it changed) and sees if it changed |
|
|
1182 | compared to the last time, invoking the callback if it did. |
|
|
1183 | |
|
|
1184 | The path does not need to exist: changing from "path exists" to "path does |
|
|
1185 | not exist" is a status change like any other. The condition "path does |
|
|
1186 | not exist" is signified by the C<st_nlink> field being zero (which is |
|
|
1187 | otherwise always forced to be at least one) and all the other fields of |
|
|
1188 | the stat buffer having unspecified contents. |
|
|
1189 | |
|
|
1190 | Since there is no standard to do this, the portable implementation simply |
|
|
1191 | calls C<stat (2)> regulalry on the path to see if it changed somehow. You |
|
|
1192 | can specify a recommended polling interval for this case. If you specify |
|
|
1193 | a polling interval of C<0> (highly recommended!) then a I<suitable, |
|
|
1194 | unspecified default> value will be used (which you can expect to be around |
|
|
1195 | five seconds, although this might change dynamically). Libev will also |
|
|
1196 | impose a minimum interval which is currently around C<0.1>, but thats |
|
|
1197 | usually overkill. |
|
|
1198 | |
|
|
1199 | This watcher type is not meant for massive numbers of stat watchers, |
|
|
1200 | as even with OS-supported change notifications, this can be |
|
|
1201 | resource-intensive. |
|
|
1202 | |
|
|
1203 | At the time of this writing, no specific OS backends are implemented, but |
|
|
1204 | if demand increases, at least a kqueue and inotify backend will be added. |
|
|
1205 | |
|
|
1206 | =over 4 |
|
|
1207 | |
|
|
1208 | =item ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval) |
|
|
1209 | |
|
|
1210 | =item ev_stat_set (ev_stat *, const char *path, ev_tstamp interval) |
|
|
1211 | |
|
|
1212 | Configures the watcher to wait for status changes of the given |
|
|
1213 | C<path>. The C<interval> is a hint on how quickly a change is expected to |
|
|
1214 | be detected and should normally be specified as C<0> to let libev choose |
|
|
1215 | a suitable value. The memory pointed to by C<path> must point to the same |
|
|
1216 | path for as long as the watcher is active. |
|
|
1217 | |
|
|
1218 | The callback will be receive C<EV_STAT> when a change was detected, |
|
|
1219 | relative to the attributes at the time the watcher was started (or the |
|
|
1220 | last change was detected). |
|
|
1221 | |
|
|
1222 | =item ev_stat_stat (ev_stat *) |
|
|
1223 | |
|
|
1224 | Updates the stat buffer immediately with new values. If you change the |
|
|
1225 | watched path in your callback, you could call this fucntion to avoid |
|
|
1226 | detecting this change (while introducing a race condition). Can also be |
|
|
1227 | useful simply to find out the new values. |
|
|
1228 | |
|
|
1229 | =item ev_statdata attr [read-only] |
|
|
1230 | |
|
|
1231 | The most-recently detected attributes of the file. Although the type is of |
|
|
1232 | C<ev_statdata>, this is usually the (or one of the) C<struct stat> types |
|
|
1233 | suitable for your system. If the C<st_nlink> member is C<0>, then there |
|
|
1234 | was some error while C<stat>ing the file. |
|
|
1235 | |
|
|
1236 | =item ev_statdata prev [read-only] |
|
|
1237 | |
|
|
1238 | The previous attributes of the file. The callback gets invoked whenever |
|
|
1239 | C<prev> != C<attr>. |
|
|
1240 | |
|
|
1241 | =item ev_tstamp interval [read-only] |
|
|
1242 | |
|
|
1243 | The specified interval. |
|
|
1244 | |
|
|
1245 | =item const char *path [read-only] |
|
|
1246 | |
|
|
1247 | The filesystem path that is being watched. |
|
|
1248 | |
|
|
1249 | =back |
|
|
1250 | |
|
|
1251 | Example: Watch C</etc/passwd> for attribute changes. |
|
|
1252 | |
|
|
1253 | static void |
|
|
1254 | passwd_cb (struct ev_loop *loop, ev_stat *w, int revents) |
|
|
1255 | { |
|
|
1256 | /* /etc/passwd changed in some way */ |
|
|
1257 | if (w->attr.st_nlink) |
|
|
1258 | { |
|
|
1259 | printf ("passwd current size %ld\n", (long)w->attr.st_size); |
|
|
1260 | printf ("passwd current atime %ld\n", (long)w->attr.st_mtime); |
|
|
1261 | printf ("passwd current mtime %ld\n", (long)w->attr.st_mtime); |
|
|
1262 | } |
|
|
1263 | else |
|
|
1264 | /* you shalt not abuse printf for puts */ |
|
|
1265 | puts ("wow, /etc/passwd is not there, expect problems. " |
|
|
1266 | "if this is windows, they already arrived\n"); |
|
|
1267 | } |
|
|
1268 | |
|
|
1269 | ... |
|
|
1270 | ev_stat passwd; |
|
|
1271 | |
|
|
1272 | ev_stat_init (&passwd, passwd_cb, "/etc/passwd"); |
|
|
1273 | ev_stat_start (loop, &passwd); |
|
|
1274 | |
|
|
1275 | |
1050 | =head2 C<ev_idle> - when you've got nothing better to do |
1276 | =head2 C<ev_idle> - when you've got nothing better to do... |
1051 | |
1277 | |
1052 | Idle watchers trigger events when there are no other events are pending |
1278 | Idle watchers trigger events when there are no other events are pending |
1053 | (prepare, check and other idle watchers do not count). That is, as long |
1279 | (prepare, check and other idle watchers do not count). That is, as long |
1054 | as your process is busy handling sockets or timeouts (or even signals, |
1280 | as your process is busy handling sockets or timeouts (or even signals, |
1055 | imagine) it will not be triggered. But when your process is idle all idle |
1281 | imagine) it will not be triggered. But when your process is idle all idle |
… | |
… | |
1089 | struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle)); |
1315 | struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle)); |
1090 | ev_idle_init (idle_watcher, idle_cb); |
1316 | ev_idle_init (idle_watcher, idle_cb); |
1091 | ev_idle_start (loop, idle_cb); |
1317 | ev_idle_start (loop, idle_cb); |
1092 | |
1318 | |
1093 | |
1319 | |
1094 | =head2 C<ev_prepare> and C<ev_check> - customise your event loop |
1320 | =head2 C<ev_prepare> and C<ev_check> - customise your event loop! |
1095 | |
1321 | |
1096 | Prepare and check watchers are usually (but not always) used in tandem: |
1322 | Prepare and check watchers are usually (but not always) used in tandem: |
1097 | prepare watchers get invoked before the process blocks and check watchers |
1323 | prepare watchers get invoked before the process blocks and check watchers |
1098 | afterwards. |
1324 | afterwards. |
1099 | |
1325 | |
|
|
1326 | You I<must not> call C<ev_loop> or similar functions that enter |
|
|
1327 | the current event loop from either C<ev_prepare> or C<ev_check> |
|
|
1328 | watchers. Other loops than the current one are fine, however. The |
|
|
1329 | rationale behind this is that you do not need to check for recursion in |
|
|
1330 | those watchers, i.e. the sequence will always be C<ev_prepare>, blocking, |
|
|
1331 | C<ev_check> so if you have one watcher of each kind they will always be |
|
|
1332 | called in pairs bracketing the blocking call. |
|
|
1333 | |
1100 | Their main purpose is to integrate other event mechanisms into libev and |
1334 | Their main purpose is to integrate other event mechanisms into libev and |
1101 | their use is somewhat advanced. This could be used, for example, to track |
1335 | their use is somewhat advanced. This could be used, for example, to track |
1102 | variable changes, implement your own watchers, integrate net-snmp or a |
1336 | variable changes, implement your own watchers, integrate net-snmp or a |
1103 | coroutine library and lots more. |
1337 | coroutine library and lots more. They are also occasionally useful if |
|
|
1338 | you cache some data and want to flush it before blocking (for example, |
|
|
1339 | in X programs you might want to do an C<XFlush ()> in an C<ev_prepare> |
|
|
1340 | watcher). |
1104 | |
1341 | |
1105 | This is done by examining in each prepare call which file descriptors need |
1342 | This is done by examining in each prepare call which file descriptors need |
1106 | to be watched by the other library, registering C<ev_io> watchers for |
1343 | to be watched by the other library, registering C<ev_io> watchers for |
1107 | them and starting an C<ev_timer> watcher for any timeouts (many libraries |
1344 | them and starting an C<ev_timer> watcher for any timeouts (many libraries |
1108 | provide just this functionality). Then, in the check watcher you check for |
1345 | provide just this functionality). Then, in the check watcher you check for |
… | |
… | |
1130 | parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set> |
1367 | parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set> |
1131 | macros, but using them is utterly, utterly and completely pointless. |
1368 | macros, but using them is utterly, utterly and completely pointless. |
1132 | |
1369 | |
1133 | =back |
1370 | =back |
1134 | |
1371 | |
1135 | Example: *TODO*. |
1372 | Example: To include a library such as adns, you would add IO watchers |
|
|
1373 | and a timeout watcher in a prepare handler, as required by libadns, and |
|
|
1374 | in a check watcher, destroy them and call into libadns. What follows is |
|
|
1375 | pseudo-code only of course: |
1136 | |
1376 | |
|
|
1377 | static ev_io iow [nfd]; |
|
|
1378 | static ev_timer tw; |
1137 | |
1379 | |
|
|
1380 | static void |
|
|
1381 | io_cb (ev_loop *loop, ev_io *w, int revents) |
|
|
1382 | { |
|
|
1383 | // set the relevant poll flags |
|
|
1384 | // could also call adns_processreadable etc. here |
|
|
1385 | struct pollfd *fd = (struct pollfd *)w->data; |
|
|
1386 | if (revents & EV_READ ) fd->revents |= fd->events & POLLIN; |
|
|
1387 | if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT; |
|
|
1388 | } |
|
|
1389 | |
|
|
1390 | // create io watchers for each fd and a timer before blocking |
|
|
1391 | static void |
|
|
1392 | adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) |
|
|
1393 | { |
|
|
1394 | int timeout = 3600000;truct pollfd fds [nfd]; |
|
|
1395 | // actual code will need to loop here and realloc etc. |
|
|
1396 | adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
|
|
1397 | |
|
|
1398 | /* the callback is illegal, but won't be called as we stop during check */ |
|
|
1399 | ev_timer_init (&tw, 0, timeout * 1e-3); |
|
|
1400 | ev_timer_start (loop, &tw); |
|
|
1401 | |
|
|
1402 | // create on ev_io per pollfd |
|
|
1403 | for (int i = 0; i < nfd; ++i) |
|
|
1404 | { |
|
|
1405 | ev_io_init (iow + i, io_cb, fds [i].fd, |
|
|
1406 | ((fds [i].events & POLLIN ? EV_READ : 0) |
|
|
1407 | | (fds [i].events & POLLOUT ? EV_WRITE : 0))); |
|
|
1408 | |
|
|
1409 | fds [i].revents = 0; |
|
|
1410 | iow [i].data = fds + i; |
|
|
1411 | ev_io_start (loop, iow + i); |
|
|
1412 | } |
|
|
1413 | } |
|
|
1414 | |
|
|
1415 | // stop all watchers after blocking |
|
|
1416 | static void |
|
|
1417 | adns_check_cb (ev_loop *loop, ev_check *w, int revents) |
|
|
1418 | { |
|
|
1419 | ev_timer_stop (loop, &tw); |
|
|
1420 | |
|
|
1421 | for (int i = 0; i < nfd; ++i) |
|
|
1422 | ev_io_stop (loop, iow + i); |
|
|
1423 | |
|
|
1424 | adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop)); |
|
|
1425 | } |
|
|
1426 | |
|
|
1427 | |
1138 | =head2 C<ev_embed> - when one backend isn't enough |
1428 | =head2 C<ev_embed> - when one backend isn't enough... |
1139 | |
1429 | |
1140 | This is a rather advanced watcher type that lets you embed one event loop |
1430 | This is a rather advanced watcher type that lets you embed one event loop |
1141 | into another (currently only C<ev_io> events are supported in the embedded |
1431 | into another (currently only C<ev_io> events are supported in the embedded |
1142 | loop, other types of watchers might be handled in a delayed or incorrect |
1432 | loop, other types of watchers might be handled in a delayed or incorrect |
1143 | fashion and must not be used). |
1433 | fashion and must not be used). |
… | |
… | |
1221 | |
1511 | |
1222 | Make a single, non-blocking sweep over the embedded loop. This works |
1512 | Make a single, non-blocking sweep over the embedded loop. This works |
1223 | similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most |
1513 | similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most |
1224 | apropriate way for embedded loops. |
1514 | apropriate way for embedded loops. |
1225 | |
1515 | |
|
|
1516 | =item struct ev_loop *loop [read-only] |
|
|
1517 | |
|
|
1518 | The embedded event loop. |
|
|
1519 | |
|
|
1520 | =back |
|
|
1521 | |
|
|
1522 | |
|
|
1523 | =head2 C<ev_fork> - the audacity to resume the event loop after a fork |
|
|
1524 | |
|
|
1525 | Fork watchers are called when a C<fork ()> was detected (usually because |
|
|
1526 | whoever is a good citizen cared to tell libev about it by calling |
|
|
1527 | C<ev_default_fork> or C<ev_loop_fork>). The invocation is done before the |
|
|
1528 | event loop blocks next and before C<ev_check> watchers are being called, |
|
|
1529 | and only in the child after the fork. If whoever good citizen calling |
|
|
1530 | C<ev_default_fork> cheats and calls it in the wrong process, the fork |
|
|
1531 | handlers will be invoked, too, of course. |
|
|
1532 | |
|
|
1533 | =over 4 |
|
|
1534 | |
|
|
1535 | =item ev_fork_init (ev_signal *, callback) |
|
|
1536 | |
|
|
1537 | Initialises and configures the fork watcher - it has no parameters of any |
|
|
1538 | kind. There is a C<ev_fork_set> macro, but using it is utterly pointless, |
|
|
1539 | believe me. |
|
|
1540 | |
1226 | =back |
1541 | =back |
1227 | |
1542 | |
1228 | |
1543 | |
1229 | =head1 OTHER FUNCTIONS |
1544 | =head1 OTHER FUNCTIONS |
1230 | |
1545 | |
… | |
… | |
1310 | |
1625 | |
1311 | =back |
1626 | =back |
1312 | |
1627 | |
1313 | =head1 C++ SUPPORT |
1628 | =head1 C++ SUPPORT |
1314 | |
1629 | |
1315 | TBD. |
1630 | Libev comes with some simplistic wrapper classes for C++ that mainly allow |
|
|
1631 | you to use some convinience methods to start/stop watchers and also change |
|
|
1632 | the callback model to a model using method callbacks on objects. |
|
|
1633 | |
|
|
1634 | To use it, |
|
|
1635 | |
|
|
1636 | #include <ev++.h> |
|
|
1637 | |
|
|
1638 | (it is not installed by default). This automatically includes F<ev.h> |
|
|
1639 | and puts all of its definitions (many of them macros) into the global |
|
|
1640 | namespace. All C++ specific things are put into the C<ev> namespace. |
|
|
1641 | |
|
|
1642 | It should support all the same embedding options as F<ev.h>, most notably |
|
|
1643 | C<EV_MULTIPLICITY>. |
|
|
1644 | |
|
|
1645 | Here is a list of things available in the C<ev> namespace: |
|
|
1646 | |
|
|
1647 | =over 4 |
|
|
1648 | |
|
|
1649 | =item C<ev::READ>, C<ev::WRITE> etc. |
|
|
1650 | |
|
|
1651 | These are just enum values with the same values as the C<EV_READ> etc. |
|
|
1652 | macros from F<ev.h>. |
|
|
1653 | |
|
|
1654 | =item C<ev::tstamp>, C<ev::now> |
|
|
1655 | |
|
|
1656 | Aliases to the same types/functions as with the C<ev_> prefix. |
|
|
1657 | |
|
|
1658 | =item C<ev::io>, C<ev::timer>, C<ev::periodic>, C<ev::idle>, C<ev::sig> etc. |
|
|
1659 | |
|
|
1660 | For each C<ev_TYPE> watcher in F<ev.h> there is a corresponding class of |
|
|
1661 | the same name in the C<ev> namespace, with the exception of C<ev_signal> |
|
|
1662 | which is called C<ev::sig> to avoid clashes with the C<signal> macro |
|
|
1663 | defines by many implementations. |
|
|
1664 | |
|
|
1665 | All of those classes have these methods: |
|
|
1666 | |
|
|
1667 | =over 4 |
|
|
1668 | |
|
|
1669 | =item ev::TYPE::TYPE (object *, object::method *) |
|
|
1670 | |
|
|
1671 | =item ev::TYPE::TYPE (object *, object::method *, struct ev_loop *) |
|
|
1672 | |
|
|
1673 | =item ev::TYPE::~TYPE |
|
|
1674 | |
|
|
1675 | The constructor takes a pointer to an object and a method pointer to |
|
|
1676 | the event handler callback to call in this class. The constructor calls |
|
|
1677 | C<ev_init> for you, which means you have to call the C<set> method |
|
|
1678 | before starting it. If you do not specify a loop then the constructor |
|
|
1679 | automatically associates the default loop with this watcher. |
|
|
1680 | |
|
|
1681 | The destructor automatically stops the watcher if it is active. |
|
|
1682 | |
|
|
1683 | =item w->set (struct ev_loop *) |
|
|
1684 | |
|
|
1685 | Associates a different C<struct ev_loop> with this watcher. You can only |
|
|
1686 | do this when the watcher is inactive (and not pending either). |
|
|
1687 | |
|
|
1688 | =item w->set ([args]) |
|
|
1689 | |
|
|
1690 | Basically the same as C<ev_TYPE_set>, with the same args. Must be |
|
|
1691 | called at least once. Unlike the C counterpart, an active watcher gets |
|
|
1692 | automatically stopped and restarted. |
|
|
1693 | |
|
|
1694 | =item w->start () |
|
|
1695 | |
|
|
1696 | Starts the watcher. Note that there is no C<loop> argument as the |
|
|
1697 | constructor already takes the loop. |
|
|
1698 | |
|
|
1699 | =item w->stop () |
|
|
1700 | |
|
|
1701 | Stops the watcher if it is active. Again, no C<loop> argument. |
|
|
1702 | |
|
|
1703 | =item w->again () C<ev::timer>, C<ev::periodic> only |
|
|
1704 | |
|
|
1705 | For C<ev::timer> and C<ev::periodic>, this invokes the corresponding |
|
|
1706 | C<ev_TYPE_again> function. |
|
|
1707 | |
|
|
1708 | =item w->sweep () C<ev::embed> only |
|
|
1709 | |
|
|
1710 | Invokes C<ev_embed_sweep>. |
|
|
1711 | |
|
|
1712 | =item w->update () C<ev::stat> only |
|
|
1713 | |
|
|
1714 | Invokes C<ev_stat_stat>. |
|
|
1715 | |
|
|
1716 | =back |
|
|
1717 | |
|
|
1718 | =back |
|
|
1719 | |
|
|
1720 | Example: Define a class with an IO and idle watcher, start one of them in |
|
|
1721 | the constructor. |
|
|
1722 | |
|
|
1723 | class myclass |
|
|
1724 | { |
|
|
1725 | ev_io io; void io_cb (ev::io &w, int revents); |
|
|
1726 | ev_idle idle void idle_cb (ev::idle &w, int revents); |
|
|
1727 | |
|
|
1728 | myclass (); |
|
|
1729 | } |
|
|
1730 | |
|
|
1731 | myclass::myclass (int fd) |
|
|
1732 | : io (this, &myclass::io_cb), |
|
|
1733 | idle (this, &myclass::idle_cb) |
|
|
1734 | { |
|
|
1735 | io.start (fd, ev::READ); |
|
|
1736 | } |
|
|
1737 | |
|
|
1738 | |
|
|
1739 | =head1 MACRO MAGIC |
|
|
1740 | |
|
|
1741 | Libev can be compiled with a variety of options, the most fundemantal is |
|
|
1742 | C<EV_MULTIPLICITY>. This option determines wether (most) functions and |
|
|
1743 | callbacks have an initial C<struct ev_loop *> argument. |
|
|
1744 | |
|
|
1745 | To make it easier to write programs that cope with either variant, the |
|
|
1746 | following macros are defined: |
|
|
1747 | |
|
|
1748 | =over 4 |
|
|
1749 | |
|
|
1750 | =item C<EV_A>, C<EV_A_> |
|
|
1751 | |
|
|
1752 | This provides the loop I<argument> for functions, if one is required ("ev |
|
|
1753 | loop argument"). The C<EV_A> form is used when this is the sole argument, |
|
|
1754 | C<EV_A_> is used when other arguments are following. Example: |
|
|
1755 | |
|
|
1756 | ev_unref (EV_A); |
|
|
1757 | ev_timer_add (EV_A_ watcher); |
|
|
1758 | ev_loop (EV_A_ 0); |
|
|
1759 | |
|
|
1760 | It assumes the variable C<loop> of type C<struct ev_loop *> is in scope, |
|
|
1761 | which is often provided by the following macro. |
|
|
1762 | |
|
|
1763 | =item C<EV_P>, C<EV_P_> |
|
|
1764 | |
|
|
1765 | This provides the loop I<parameter> for functions, if one is required ("ev |
|
|
1766 | loop parameter"). The C<EV_P> form is used when this is the sole parameter, |
|
|
1767 | C<EV_P_> is used when other parameters are following. Example: |
|
|
1768 | |
|
|
1769 | // this is how ev_unref is being declared |
|
|
1770 | static void ev_unref (EV_P); |
|
|
1771 | |
|
|
1772 | // this is how you can declare your typical callback |
|
|
1773 | static void cb (EV_P_ ev_timer *w, int revents) |
|
|
1774 | |
|
|
1775 | It declares a parameter C<loop> of type C<struct ev_loop *>, quite |
|
|
1776 | suitable for use with C<EV_A>. |
|
|
1777 | |
|
|
1778 | =item C<EV_DEFAULT>, C<EV_DEFAULT_> |
|
|
1779 | |
|
|
1780 | Similar to the other two macros, this gives you the value of the default |
|
|
1781 | loop, if multiple loops are supported ("ev loop default"). |
|
|
1782 | |
|
|
1783 | =back |
|
|
1784 | |
|
|
1785 | Example: Declare and initialise a check watcher, working regardless of |
|
|
1786 | wether multiple loops are supported or not. |
|
|
1787 | |
|
|
1788 | static void |
|
|
1789 | check_cb (EV_P_ ev_timer *w, int revents) |
|
|
1790 | { |
|
|
1791 | ev_check_stop (EV_A_ w); |
|
|
1792 | } |
|
|
1793 | |
|
|
1794 | ev_check check; |
|
|
1795 | ev_check_init (&check, check_cb); |
|
|
1796 | ev_check_start (EV_DEFAULT_ &check); |
|
|
1797 | ev_loop (EV_DEFAULT_ 0); |
|
|
1798 | |
|
|
1799 | |
|
|
1800 | =head1 EMBEDDING |
|
|
1801 | |
|
|
1802 | Libev can (and often is) directly embedded into host |
|
|
1803 | applications. Examples of applications that embed it include the Deliantra |
|
|
1804 | Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe) |
|
|
1805 | and rxvt-unicode. |
|
|
1806 | |
|
|
1807 | The goal is to enable you to just copy the neecssary files into your |
|
|
1808 | source directory without having to change even a single line in them, so |
|
|
1809 | you can easily upgrade by simply copying (or having a checked-out copy of |
|
|
1810 | libev somewhere in your source tree). |
|
|
1811 | |
|
|
1812 | =head2 FILESETS |
|
|
1813 | |
|
|
1814 | Depending on what features you need you need to include one or more sets of files |
|
|
1815 | in your app. |
|
|
1816 | |
|
|
1817 | =head3 CORE EVENT LOOP |
|
|
1818 | |
|
|
1819 | To include only the libev core (all the C<ev_*> functions), with manual |
|
|
1820 | configuration (no autoconf): |
|
|
1821 | |
|
|
1822 | #define EV_STANDALONE 1 |
|
|
1823 | #include "ev.c" |
|
|
1824 | |
|
|
1825 | This will automatically include F<ev.h>, too, and should be done in a |
|
|
1826 | single C source file only to provide the function implementations. To use |
|
|
1827 | it, do the same for F<ev.h> in all files wishing to use this API (best |
|
|
1828 | done by writing a wrapper around F<ev.h> that you can include instead and |
|
|
1829 | where you can put other configuration options): |
|
|
1830 | |
|
|
1831 | #define EV_STANDALONE 1 |
|
|
1832 | #include "ev.h" |
|
|
1833 | |
|
|
1834 | Both header files and implementation files can be compiled with a C++ |
|
|
1835 | compiler (at least, thats a stated goal, and breakage will be treated |
|
|
1836 | as a bug). |
|
|
1837 | |
|
|
1838 | You need the following files in your source tree, or in a directory |
|
|
1839 | in your include path (e.g. in libev/ when using -Ilibev): |
|
|
1840 | |
|
|
1841 | ev.h |
|
|
1842 | ev.c |
|
|
1843 | ev_vars.h |
|
|
1844 | ev_wrap.h |
|
|
1845 | |
|
|
1846 | ev_win32.c required on win32 platforms only |
|
|
1847 | |
|
|
1848 | ev_select.c only when select backend is enabled (which is by default) |
|
|
1849 | ev_poll.c only when poll backend is enabled (disabled by default) |
|
|
1850 | ev_epoll.c only when the epoll backend is enabled (disabled by default) |
|
|
1851 | ev_kqueue.c only when the kqueue backend is enabled (disabled by default) |
|
|
1852 | ev_port.c only when the solaris port backend is enabled (disabled by default) |
|
|
1853 | |
|
|
1854 | F<ev.c> includes the backend files directly when enabled, so you only need |
|
|
1855 | to compile this single file. |
|
|
1856 | |
|
|
1857 | =head3 LIBEVENT COMPATIBILITY API |
|
|
1858 | |
|
|
1859 | To include the libevent compatibility API, also include: |
|
|
1860 | |
|
|
1861 | #include "event.c" |
|
|
1862 | |
|
|
1863 | in the file including F<ev.c>, and: |
|
|
1864 | |
|
|
1865 | #include "event.h" |
|
|
1866 | |
|
|
1867 | in the files that want to use the libevent API. This also includes F<ev.h>. |
|
|
1868 | |
|
|
1869 | You need the following additional files for this: |
|
|
1870 | |
|
|
1871 | event.h |
|
|
1872 | event.c |
|
|
1873 | |
|
|
1874 | =head3 AUTOCONF SUPPORT |
|
|
1875 | |
|
|
1876 | Instead of using C<EV_STANDALONE=1> and providing your config in |
|
|
1877 | whatever way you want, you can also C<m4_include([libev.m4])> in your |
|
|
1878 | F<configure.ac> and leave C<EV_STANDALONE> undefined. F<ev.c> will then |
|
|
1879 | include F<config.h> and configure itself accordingly. |
|
|
1880 | |
|
|
1881 | For this of course you need the m4 file: |
|
|
1882 | |
|
|
1883 | libev.m4 |
|
|
1884 | |
|
|
1885 | =head2 PREPROCESSOR SYMBOLS/MACROS |
|
|
1886 | |
|
|
1887 | Libev can be configured via a variety of preprocessor symbols you have to define |
|
|
1888 | before including any of its files. The default is not to build for multiplicity |
|
|
1889 | and only include the select backend. |
|
|
1890 | |
|
|
1891 | =over 4 |
|
|
1892 | |
|
|
1893 | =item EV_STANDALONE |
|
|
1894 | |
|
|
1895 | Must always be C<1> if you do not use autoconf configuration, which |
|
|
1896 | keeps libev from including F<config.h>, and it also defines dummy |
|
|
1897 | implementations for some libevent functions (such as logging, which is not |
|
|
1898 | supported). It will also not define any of the structs usually found in |
|
|
1899 | F<event.h> that are not directly supported by the libev core alone. |
|
|
1900 | |
|
|
1901 | =item EV_USE_MONOTONIC |
|
|
1902 | |
|
|
1903 | If defined to be C<1>, libev will try to detect the availability of the |
|
|
1904 | monotonic clock option at both compiletime and runtime. Otherwise no use |
|
|
1905 | of the monotonic clock option will be attempted. If you enable this, you |
|
|
1906 | usually have to link against librt or something similar. Enabling it when |
|
|
1907 | the functionality isn't available is safe, though, althoguh you have |
|
|
1908 | to make sure you link against any libraries where the C<clock_gettime> |
|
|
1909 | function is hiding in (often F<-lrt>). |
|
|
1910 | |
|
|
1911 | =item EV_USE_REALTIME |
|
|
1912 | |
|
|
1913 | If defined to be C<1>, libev will try to detect the availability of the |
|
|
1914 | realtime clock option at compiletime (and assume its availability at |
|
|
1915 | runtime if successful). Otherwise no use of the realtime clock option will |
|
|
1916 | be attempted. This effectively replaces C<gettimeofday> by C<clock_get |
|
|
1917 | (CLOCK_REALTIME, ...)> and will not normally affect correctness. See tzhe note about libraries |
|
|
1918 | in the description of C<EV_USE_MONOTONIC>, though. |
|
|
1919 | |
|
|
1920 | =item EV_USE_SELECT |
|
|
1921 | |
|
|
1922 | If undefined or defined to be C<1>, libev will compile in support for the |
|
|
1923 | C<select>(2) backend. No attempt at autodetection will be done: if no |
|
|
1924 | other method takes over, select will be it. Otherwise the select backend |
|
|
1925 | will not be compiled in. |
|
|
1926 | |
|
|
1927 | =item EV_SELECT_USE_FD_SET |
|
|
1928 | |
|
|
1929 | If defined to C<1>, then the select backend will use the system C<fd_set> |
|
|
1930 | structure. This is useful if libev doesn't compile due to a missing |
|
|
1931 | C<NFDBITS> or C<fd_mask> definition or it misguesses the bitset layout on |
|
|
1932 | exotic systems. This usually limits the range of file descriptors to some |
|
|
1933 | low limit such as 1024 or might have other limitations (winsocket only |
|
|
1934 | allows 64 sockets). The C<FD_SETSIZE> macro, set before compilation, might |
|
|
1935 | influence the size of the C<fd_set> used. |
|
|
1936 | |
|
|
1937 | =item EV_SELECT_IS_WINSOCKET |
|
|
1938 | |
|
|
1939 | When defined to C<1>, the select backend will assume that |
|
|
1940 | select/socket/connect etc. don't understand file descriptors but |
|
|
1941 | wants osf handles on win32 (this is the case when the select to |
|
|
1942 | be used is the winsock select). This means that it will call |
|
|
1943 | C<_get_osfhandle> on the fd to convert it to an OS handle. Otherwise, |
|
|
1944 | it is assumed that all these functions actually work on fds, even |
|
|
1945 | on win32. Should not be defined on non-win32 platforms. |
|
|
1946 | |
|
|
1947 | =item EV_USE_POLL |
|
|
1948 | |
|
|
1949 | If defined to be C<1>, libev will compile in support for the C<poll>(2) |
|
|
1950 | backend. Otherwise it will be enabled on non-win32 platforms. It |
|
|
1951 | takes precedence over select. |
|
|
1952 | |
|
|
1953 | =item EV_USE_EPOLL |
|
|
1954 | |
|
|
1955 | If defined to be C<1>, libev will compile in support for the Linux |
|
|
1956 | C<epoll>(7) backend. Its availability will be detected at runtime, |
|
|
1957 | otherwise another method will be used as fallback. This is the |
|
|
1958 | preferred backend for GNU/Linux systems. |
|
|
1959 | |
|
|
1960 | =item EV_USE_KQUEUE |
|
|
1961 | |
|
|
1962 | If defined to be C<1>, libev will compile in support for the BSD style |
|
|
1963 | C<kqueue>(2) backend. Its actual availability will be detected at runtime, |
|
|
1964 | otherwise another method will be used as fallback. This is the preferred |
|
|
1965 | backend for BSD and BSD-like systems, although on most BSDs kqueue only |
|
|
1966 | supports some types of fds correctly (the only platform we found that |
|
|
1967 | supports ptys for example was NetBSD), so kqueue might be compiled in, but |
|
|
1968 | not be used unless explicitly requested. The best way to use it is to find |
|
|
1969 | out whether kqueue supports your type of fd properly and use an embedded |
|
|
1970 | kqueue loop. |
|
|
1971 | |
|
|
1972 | =item EV_USE_PORT |
|
|
1973 | |
|
|
1974 | If defined to be C<1>, libev will compile in support for the Solaris |
|
|
1975 | 10 port style backend. Its availability will be detected at runtime, |
|
|
1976 | otherwise another method will be used as fallback. This is the preferred |
|
|
1977 | backend for Solaris 10 systems. |
|
|
1978 | |
|
|
1979 | =item EV_USE_DEVPOLL |
|
|
1980 | |
|
|
1981 | reserved for future expansion, works like the USE symbols above. |
|
|
1982 | |
|
|
1983 | =item EV_H |
|
|
1984 | |
|
|
1985 | The name of the F<ev.h> header file used to include it. The default if |
|
|
1986 | undefined is C<< <ev.h> >> in F<event.h> and C<"ev.h"> in F<ev.c>. This |
|
|
1987 | can be used to virtually rename the F<ev.h> header file in case of conflicts. |
|
|
1988 | |
|
|
1989 | =item EV_CONFIG_H |
|
|
1990 | |
|
|
1991 | If C<EV_STANDALONE> isn't C<1>, this variable can be used to override |
|
|
1992 | F<ev.c>'s idea of where to find the F<config.h> file, similarly to |
|
|
1993 | C<EV_H>, above. |
|
|
1994 | |
|
|
1995 | =item EV_EVENT_H |
|
|
1996 | |
|
|
1997 | Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea |
|
|
1998 | of how the F<event.h> header can be found. |
|
|
1999 | |
|
|
2000 | =item EV_PROTOTYPES |
|
|
2001 | |
|
|
2002 | If defined to be C<0>, then F<ev.h> will not define any function |
|
|
2003 | prototypes, but still define all the structs and other symbols. This is |
|
|
2004 | occasionally useful if you want to provide your own wrapper functions |
|
|
2005 | around libev functions. |
|
|
2006 | |
|
|
2007 | =item EV_MULTIPLICITY |
|
|
2008 | |
|
|
2009 | If undefined or defined to C<1>, then all event-loop-specific functions |
|
|
2010 | will have the C<struct ev_loop *> as first argument, and you can create |
|
|
2011 | additional independent event loops. Otherwise there will be no support |
|
|
2012 | for multiple event loops and there is no first event loop pointer |
|
|
2013 | argument. Instead, all functions act on the single default loop. |
|
|
2014 | |
|
|
2015 | =item EV_PERIODIC_ENABLE |
|
|
2016 | |
|
|
2017 | If undefined or defined to be C<1>, then periodic timers are supported. If |
|
|
2018 | defined to be C<0>, then they are not. Disabling them saves a few kB of |
|
|
2019 | code. |
|
|
2020 | |
|
|
2021 | =item EV_EMBED_ENABLE |
|
|
2022 | |
|
|
2023 | If undefined or defined to be C<1>, then embed watchers are supported. If |
|
|
2024 | defined to be C<0>, then they are not. |
|
|
2025 | |
|
|
2026 | =item EV_STAT_ENABLE |
|
|
2027 | |
|
|
2028 | If undefined or defined to be C<1>, then stat watchers are supported. If |
|
|
2029 | defined to be C<0>, then they are not. |
|
|
2030 | |
|
|
2031 | =item EV_FORK_ENABLE |
|
|
2032 | |
|
|
2033 | If undefined or defined to be C<1>, then fork watchers are supported. If |
|
|
2034 | defined to be C<0>, then they are not. |
|
|
2035 | |
|
|
2036 | =item EV_MINIMAL |
|
|
2037 | |
|
|
2038 | If you need to shave off some kilobytes of code at the expense of some |
|
|
2039 | speed, define this symbol to C<1>. Currently only used for gcc to override |
|
|
2040 | some inlining decisions, saves roughly 30% codesize of amd64. |
|
|
2041 | |
|
|
2042 | =item EV_PID_HASHSIZE |
|
|
2043 | |
|
|
2044 | C<ev_child> watchers use a small hash table to distribute workload by |
|
|
2045 | pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more |
|
|
2046 | than enough. If you need to manage thousands of children you might want to |
|
|
2047 | increase this value. |
|
|
2048 | |
|
|
2049 | =item EV_COMMON |
|
|
2050 | |
|
|
2051 | By default, all watchers have a C<void *data> member. By redefining |
|
|
2052 | this macro to a something else you can include more and other types of |
|
|
2053 | members. You have to define it each time you include one of the files, |
|
|
2054 | though, and it must be identical each time. |
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2055 | |
|
|
2056 | For example, the perl EV module uses something like this: |
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2057 | |
|
|
2058 | #define EV_COMMON \ |
|
|
2059 | SV *self; /* contains this struct */ \ |
|
|
2060 | SV *cb_sv, *fh /* note no trailing ";" */ |
|
|
2061 | |
|
|
2062 | =item EV_CB_DECLARE (type) |
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2063 | |
|
|
2064 | =item EV_CB_INVOKE (watcher, revents) |
|
|
2065 | |
|
|
2066 | =item ev_set_cb (ev, cb) |
|
|
2067 | |
|
|
2068 | Can be used to change the callback member declaration in each watcher, |
|
|
2069 | and the way callbacks are invoked and set. Must expand to a struct member |
|
|
2070 | definition and a statement, respectively. See the F<ev.v> header file for |
|
|
2071 | their default definitions. One possible use for overriding these is to |
|
|
2072 | avoid the C<struct ev_loop *> as first argument in all cases, or to use |
|
|
2073 | method calls instead of plain function calls in C++. |
|
|
2074 | |
|
|
2075 | =head2 EXAMPLES |
|
|
2076 | |
|
|
2077 | For a real-world example of a program the includes libev |
|
|
2078 | verbatim, you can have a look at the EV perl module |
|
|
2079 | (L<http://software.schmorp.de/pkg/EV.html>). It has the libev files in |
|
|
2080 | the F<libev/> subdirectory and includes them in the F<EV/EVAPI.h> (public |
|
|
2081 | interface) and F<EV.xs> (implementation) files. Only the F<EV.xs> file |
|
|
2082 | will be compiled. It is pretty complex because it provides its own header |
|
|
2083 | file. |
|
|
2084 | |
|
|
2085 | The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file |
|
|
2086 | that everybody includes and which overrides some autoconf choices: |
|
|
2087 | |
|
|
2088 | #define EV_USE_POLL 0 |
|
|
2089 | #define EV_MULTIPLICITY 0 |
|
|
2090 | #define EV_PERIODICS 0 |
|
|
2091 | #define EV_CONFIG_H <config.h> |
|
|
2092 | |
|
|
2093 | #include "ev++.h" |
|
|
2094 | |
|
|
2095 | And a F<ev_cpp.C> implementation file that contains libev proper and is compiled: |
|
|
2096 | |
|
|
2097 | #include "ev_cpp.h" |
|
|
2098 | #include "ev.c" |
|
|
2099 | |
|
|
2100 | |
|
|
2101 | =head1 COMPLEXITIES |
|
|
2102 | |
|
|
2103 | In this section the complexities of (many of) the algorithms used inside |
|
|
2104 | libev will be explained. For complexity discussions about backends see the |
|
|
2105 | documentation for C<ev_default_init>. |
|
|
2106 | |
|
|
2107 | =over 4 |
|
|
2108 | |
|
|
2109 | =item Starting and stopping timer/periodic watchers: O(log skipped_other_timers) |
|
|
2110 | |
|
|
2111 | =item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers) |
|
|
2112 | |
|
|
2113 | =item Starting io/check/prepare/idle/signal/child watchers: O(1) |
|
|
2114 | |
|
|
2115 | =item Stopping check/prepare/idle watchers: O(1) |
|
|
2116 | |
|
|
2117 | =item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % 16)) |
|
|
2118 | |
|
|
2119 | =item Finding the next timer per loop iteration: O(1) |
|
|
2120 | |
|
|
2121 | =item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd) |
|
|
2122 | |
|
|
2123 | =item Activating one watcher: O(1) |
|
|
2124 | |
|
|
2125 | =back |
|
|
2126 | |
1316 | |
2127 | |
1317 | =head1 AUTHOR |
2128 | =head1 AUTHOR |
1318 | |
2129 | |
1319 | Marc Lehmann <libev@schmorp.de>. |
2130 | Marc Lehmann <libev@schmorp.de>. |
1320 | |
2131 | |