… | |
… | |
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 | |
7 | #include <ev.h> |
7 | #include <ev.h> |
|
|
8 | |
|
|
9 | =head1 EXAMPLE PROGRAM |
|
|
10 | |
|
|
11 | #include <ev.h> |
|
|
12 | |
|
|
13 | ev_io stdin_watcher; |
|
|
14 | ev_timer timeout_watcher; |
|
|
15 | |
|
|
16 | /* called when data readable on stdin */ |
|
|
17 | static void |
|
|
18 | stdin_cb (EV_P_ struct ev_io *w, int revents) |
|
|
19 | { |
|
|
20 | /* puts ("stdin ready"); */ |
|
|
21 | ev_io_stop (EV_A_ w); /* just a syntax example */ |
|
|
22 | ev_unloop (EV_A_ EVUNLOOP_ALL); /* leave all loop calls */ |
|
|
23 | } |
|
|
24 | |
|
|
25 | static void |
|
|
26 | timeout_cb (EV_P_ struct ev_timer *w, int revents) |
|
|
27 | { |
|
|
28 | /* puts ("timeout"); */ |
|
|
29 | ev_unloop (EV_A_ EVUNLOOP_ONE); /* leave one loop call */ |
|
|
30 | } |
|
|
31 | |
|
|
32 | int |
|
|
33 | main (void) |
|
|
34 | { |
|
|
35 | struct ev_loop *loop = ev_default_loop (0); |
|
|
36 | |
|
|
37 | /* initialise an io watcher, then start it */ |
|
|
38 | ev_io_init (&stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ); |
|
|
39 | ev_io_start (loop, &stdin_watcher); |
|
|
40 | |
|
|
41 | /* simple non-repeating 5.5 second timeout */ |
|
|
42 | ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.); |
|
|
43 | ev_timer_start (loop, &timeout_watcher); |
|
|
44 | |
|
|
45 | /* loop till timeout or data ready */ |
|
|
46 | ev_loop (loop, 0); |
|
|
47 | |
|
|
48 | return 0; |
|
|
49 | } |
8 | |
50 | |
9 | =head1 DESCRIPTION |
51 | =head1 DESCRIPTION |
10 | |
52 | |
11 | Libev is an event loop: you register interest in certain events (such as a |
53 | 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 |
54 | file descriptor being readable or a timeout occuring), and it will manage |
… | |
… | |
21 | details of the event, and then hand it over to libev by I<starting> the |
63 | details of the event, and then hand it over to libev by I<starting> the |
22 | watcher. |
64 | watcher. |
23 | |
65 | |
24 | =head1 FEATURES |
66 | =head1 FEATURES |
25 | |
67 | |
26 | Libev supports select, poll, the linux-specific epoll and the bsd-specific |
68 | Libev supports C<select>, C<poll>, the Linux-specific C<epoll>, the |
27 | kqueue mechanisms for file descriptor events, relative timers, absolute |
69 | BSD-specific C<kqueue> and the Solaris-specific event port mechanisms |
28 | timers with customised rescheduling, signal events, process status change |
70 | for file descriptor events (C<ev_io>), the Linux C<inotify> interface |
29 | events (related to SIGCHLD), and event watchers dealing with the event |
71 | (for C<ev_stat>), relative timers (C<ev_timer>), absolute timers |
30 | loop mechanism itself (idle, prepare and check watchers). It also is quite |
72 | with customised rescheduling (C<ev_periodic>), synchronous signals |
|
|
73 | (C<ev_signal>), process status change events (C<ev_child>), and event |
|
|
74 | watchers dealing with the event loop mechanism itself (C<ev_idle>, |
|
|
75 | C<ev_embed>, C<ev_prepare> and C<ev_check> watchers) as well as |
|
|
76 | file watchers (C<ev_stat>) and even limited support for fork events |
|
|
77 | (C<ev_fork>). |
|
|
78 | |
|
|
79 | It also is quite fast (see this |
31 | fast (see this L<benchmark|http://libev.schmorp.de/bench.html> comparing |
80 | L<benchmark|http://libev.schmorp.de/bench.html> comparing it to libevent |
32 | it to libevent for example). |
81 | for example). |
33 | |
82 | |
34 | =head1 CONVENTIONS |
83 | =head1 CONVENTIONS |
35 | |
84 | |
36 | Libev is very configurable. In this manual the default configuration |
85 | Libev is very configurable. In this manual the default configuration will |
37 | will be described, which supports multiple event loops. For more info |
86 | be described, which supports multiple event loops. For more info about |
38 | about various configuration options please have a look at the file |
87 | various configuration options please have a look at B<EMBED> section in |
39 | F<README.embed> in the libev distribution. If libev was configured without |
88 | this manual. If libev was configured without support for multiple event |
40 | support for multiple event loops, then all functions taking an initial |
89 | loops, then all functions taking an initial argument of name C<loop> |
41 | argument of name C<loop> (which is always of type C<struct ev_loop *>) |
90 | (which is always of type C<struct ev_loop *>) will not have this argument. |
42 | will not have this argument. |
|
|
43 | |
91 | |
44 | =head1 TIME REPRESENTATION |
92 | =head1 TIME REPRESENTATION |
45 | |
93 | |
46 | Libev represents time as a single floating point number, representing the |
94 | Libev represents time as a single floating point number, representing the |
47 | (fractional) number of seconds since the (POSIX) epoch (somewhere near |
95 | (fractional) number of seconds since the (POSIX) epoch (somewhere near |
48 | the beginning of 1970, details are complicated, don't ask). This type is |
96 | 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 |
97 | 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 |
98 | to the C<double> type in C, and when you need to do any calculations on |
51 | it, you should treat it as such. |
99 | it, you should treat it as such. |
52 | |
100 | |
53 | |
|
|
54 | =head1 GLOBAL FUNCTIONS |
101 | =head1 GLOBAL FUNCTIONS |
55 | |
102 | |
56 | These functions can be called anytime, even before initialising the |
103 | These functions can be called anytime, even before initialising the |
57 | library in any way. |
104 | library in any way. |
58 | |
105 | |
… | |
… | |
77 | Usually, it's a good idea to terminate if the major versions mismatch, |
124 | Usually, it's a good idea to terminate if the major versions mismatch, |
78 | as this indicates an incompatible change. Minor versions are usually |
125 | as this indicates an incompatible change. Minor versions are usually |
79 | compatible to older versions, so a larger minor version alone is usually |
126 | compatible to older versions, so a larger minor version alone is usually |
80 | not a problem. |
127 | not a problem. |
81 | |
128 | |
82 | Example: make sure we haven't accidentally been linked against the wrong |
129 | Example: Make sure we haven't accidentally been linked against the wrong |
83 | version: |
130 | version. |
84 | |
131 | |
85 | assert (("libev version mismatch", |
132 | assert (("libev version mismatch", |
86 | ev_version_major () == EV_VERSION_MAJOR |
133 | ev_version_major () == EV_VERSION_MAJOR |
87 | && ev_version_minor () >= EV_VERSION_MINOR)); |
134 | && ev_version_minor () >= EV_VERSION_MINOR)); |
88 | |
135 | |
… | |
… | |
118 | |
165 | |
119 | See the description of C<ev_embed> watchers for more info. |
166 | See the description of C<ev_embed> watchers for more info. |
120 | |
167 | |
121 | =item ev_set_allocator (void *(*cb)(void *ptr, long size)) |
168 | =item ev_set_allocator (void *(*cb)(void *ptr, long size)) |
122 | |
169 | |
123 | Sets the allocation function to use (the prototype is similar to the |
170 | Sets the allocation function to use (the prototype is similar - the |
124 | realloc C function, the semantics are identical). It is used to allocate |
171 | semantics is identical - to the realloc C function). It is used to |
125 | and free memory (no surprises here). If it returns zero when memory |
172 | allocate and free memory (no surprises here). If it returns zero when |
126 | needs to be allocated, the library might abort or take some potentially |
173 | memory needs to be allocated, the library might abort or take some |
127 | destructive action. The default is your system realloc function. |
174 | potentially destructive action. The default is your system realloc |
|
|
175 | function. |
128 | |
176 | |
129 | You could override this function in high-availability programs to, say, |
177 | 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, |
178 | 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. |
179 | or even to sleep a while and retry until some memory is available. |
132 | |
180 | |
133 | Example: replace the libev allocator with one that waits a bit and then |
181 | Example: Replace the libev allocator with one that waits a bit and then |
134 | retries: better than mine). |
182 | retries). |
135 | |
183 | |
136 | static void * |
184 | static void * |
137 | persistent_realloc (void *ptr, long size) |
185 | persistent_realloc (void *ptr, size_t size) |
138 | { |
186 | { |
139 | for (;;) |
187 | for (;;) |
140 | { |
188 | { |
141 | void *newptr = realloc (ptr, size); |
189 | void *newptr = realloc (ptr, size); |
142 | |
190 | |
… | |
… | |
158 | callback is set, then libev will expect it to remedy the sitution, no |
206 | callback is set, then libev will expect it to remedy the sitution, no |
159 | matter what, when it returns. That is, libev will generally retry the |
207 | matter what, when it returns. That is, libev will generally retry the |
160 | requested operation, or, if the condition doesn't go away, do bad stuff |
208 | requested operation, or, if the condition doesn't go away, do bad stuff |
161 | (such as abort). |
209 | (such as abort). |
162 | |
210 | |
163 | Example: do the same thing as libev does internally: |
211 | Example: This is basically the same thing that libev does internally, too. |
164 | |
212 | |
165 | static void |
213 | static void |
166 | fatal_error (const char *msg) |
214 | fatal_error (const char *msg) |
167 | { |
215 | { |
168 | perror (msg); |
216 | perror (msg); |
… | |
… | |
218 | C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will |
266 | C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will |
219 | override the flags completely if it is found in the environment. This is |
267 | override the flags completely if it is found in the environment. This is |
220 | useful to try out specific backends to test their performance, or to work |
268 | useful to try out specific backends to test their performance, or to work |
221 | around bugs. |
269 | around bugs. |
222 | |
270 | |
|
|
271 | =item C<EVFLAG_FORKCHECK> |
|
|
272 | |
|
|
273 | Instead of calling C<ev_default_fork> or C<ev_loop_fork> manually after |
|
|
274 | a fork, you can also make libev check for a fork in each iteration by |
|
|
275 | enabling this flag. |
|
|
276 | |
|
|
277 | This works by calling C<getpid ()> on every iteration of the loop, |
|
|
278 | and thus this might slow down your event loop if you do a lot of loop |
|
|
279 | iterations and little real work, but is usually not noticable (on my |
|
|
280 | Linux system for example, C<getpid> is actually a simple 5-insn sequence |
|
|
281 | without a syscall and thus I<very> fast, but my Linux system also has |
|
|
282 | C<pthread_atfork> which is even faster). |
|
|
283 | |
|
|
284 | The big advantage of this flag is that you can forget about fork (and |
|
|
285 | forget about forgetting to tell libev about forking) when you use this |
|
|
286 | flag. |
|
|
287 | |
|
|
288 | This flag setting cannot be overriden or specified in the C<LIBEV_FLAGS> |
|
|
289 | environment variable. |
|
|
290 | |
223 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
291 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
224 | |
292 | |
225 | This is your standard select(2) backend. Not I<completely> standard, as |
293 | This is your standard select(2) backend. Not I<completely> standard, as |
226 | libev tries to roll its own fd_set with no limits on the number of fds, |
294 | libev tries to roll its own fd_set with no limits on the number of fds, |
227 | but if that fails, expect a fairly low limit on the number of fds when |
295 | but if that fails, expect a fairly low limit on the number of fds when |
… | |
… | |
314 | Similar to C<ev_default_loop>, but always creates a new event loop that is |
382 | Similar to C<ev_default_loop>, but always creates a new event loop that is |
315 | always distinct from the default loop. Unlike the default loop, it cannot |
383 | always distinct from the default loop. Unlike the default loop, it cannot |
316 | handle signal and child watchers, and attempts to do so will be greeted by |
384 | handle signal and child watchers, and attempts to do so will be greeted by |
317 | undefined behaviour (or a failed assertion if assertions are enabled). |
385 | undefined behaviour (or a failed assertion if assertions are enabled). |
318 | |
386 | |
319 | Example: try to create a event loop that uses epoll and nothing else. |
387 | Example: Try to create a event loop that uses epoll and nothing else. |
320 | |
388 | |
321 | struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); |
389 | struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); |
322 | if (!epoller) |
390 | if (!epoller) |
323 | fatal ("no epoll found here, maybe it hides under your chair"); |
391 | fatal ("no epoll found here, maybe it hides under your chair"); |
324 | |
392 | |
… | |
… | |
423 | Signals and child watchers are implemented as I/O watchers, and will |
491 | Signals and child watchers are implemented as I/O watchers, and will |
424 | be handled here by queueing them when their watcher gets executed. |
492 | be handled here by queueing them when their watcher gets executed. |
425 | - If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
493 | - If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK |
426 | were used, return, otherwise continue with step *. |
494 | were used, return, otherwise continue with step *. |
427 | |
495 | |
428 | Example: queue some jobs and then loop until no events are outsanding |
496 | Example: Queue some jobs and then loop until no events are outsanding |
429 | anymore. |
497 | anymore. |
430 | |
498 | |
431 | ... queue jobs here, make sure they register event watchers as long |
499 | ... queue jobs here, make sure they register event watchers as long |
432 | ... as they still have work to do (even an idle watcher will do..) |
500 | ... as they still have work to do (even an idle watcher will do..) |
433 | ev_loop (my_loop, 0); |
501 | ev_loop (my_loop, 0); |
… | |
… | |
453 | visible to the libev user and should not keep C<ev_loop> from exiting if |
521 | visible to the libev user and should not keep C<ev_loop> from exiting if |
454 | no event watchers registered by it are active. It is also an excellent |
522 | no event watchers registered by it are active. It is also an excellent |
455 | way to do this for generic recurring timers or from within third-party |
523 | way to do this for generic recurring timers or from within third-party |
456 | libraries. Just remember to I<unref after start> and I<ref before stop>. |
524 | libraries. Just remember to I<unref after start> and I<ref before stop>. |
457 | |
525 | |
458 | Example: create a signal watcher, but keep it from keeping C<ev_loop> |
526 | Example: Create a signal watcher, but keep it from keeping C<ev_loop> |
459 | running when nothing else is active. |
527 | running when nothing else is active. |
460 | |
528 | |
461 | struct dv_signal exitsig; |
529 | struct ev_signal exitsig; |
462 | ev_signal_init (&exitsig, sig_cb, SIGINT); |
530 | ev_signal_init (&exitsig, sig_cb, SIGINT); |
463 | ev_signal_start (myloop, &exitsig); |
531 | ev_signal_start (loop, &exitsig); |
464 | evf_unref (myloop); |
532 | evf_unref (loop); |
465 | |
533 | |
466 | Example: for some weird reason, unregister the above signal handler again. |
534 | Example: For some weird reason, unregister the above signal handler again. |
467 | |
535 | |
468 | ev_ref (myloop); |
536 | ev_ref (loop); |
469 | ev_signal_stop (myloop, &exitsig); |
537 | ev_signal_stop (loop, &exitsig); |
470 | |
538 | |
471 | =back |
539 | =back |
|
|
540 | |
472 | |
541 | |
473 | =head1 ANATOMY OF A WATCHER |
542 | =head1 ANATOMY OF A WATCHER |
474 | |
543 | |
475 | A watcher is a structure that you create and register to record your |
544 | 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 |
545 | interest in some event. For instance, if you want to wait for STDIN to |
… | |
… | |
543 | The signal specified in the C<ev_signal> watcher has been received by a thread. |
612 | The signal specified in the C<ev_signal> watcher has been received by a thread. |
544 | |
613 | |
545 | =item C<EV_CHILD> |
614 | =item C<EV_CHILD> |
546 | |
615 | |
547 | The pid specified in the C<ev_child> watcher has received a status change. |
616 | The pid specified in the C<ev_child> watcher has received a status change. |
|
|
617 | |
|
|
618 | =item C<EV_STAT> |
|
|
619 | |
|
|
620 | The path specified in the C<ev_stat> watcher changed its attributes somehow. |
548 | |
621 | |
549 | =item C<EV_IDLE> |
622 | =item C<EV_IDLE> |
550 | |
623 | |
551 | The C<ev_idle> watcher has determined that you have nothing better to do. |
624 | The C<ev_idle> watcher has determined that you have nothing better to do. |
552 | |
625 | |
… | |
… | |
560 | received events. Callbacks of both watcher types can start and stop as |
633 | 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 |
634 | 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 |
635 | (for example, a C<ev_prepare> watcher might start an idle watcher to keep |
563 | C<ev_loop> from blocking). |
636 | C<ev_loop> from blocking). |
564 | |
637 | |
|
|
638 | =item C<EV_EMBED> |
|
|
639 | |
|
|
640 | The embedded event loop specified in the C<ev_embed> watcher needs attention. |
|
|
641 | |
|
|
642 | =item C<EV_FORK> |
|
|
643 | |
|
|
644 | The event loop has been resumed in the child process after fork (see |
|
|
645 | C<ev_fork>). |
|
|
646 | |
565 | =item C<EV_ERROR> |
647 | =item C<EV_ERROR> |
566 | |
648 | |
567 | An unspecified error has occured, the watcher has been stopped. This might |
649 | An unspecified error has occured, the watcher has been stopped. This might |
568 | happen because the watcher could not be properly started because libev |
650 | 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 |
651 | ran out of memory, a file descriptor was found to be closed or any other |
… | |
… | |
576 | with the error from read() or write(). This will not work in multithreaded |
658 | with the error from read() or write(). This will not work in multithreaded |
577 | programs, though, so beware. |
659 | programs, though, so beware. |
578 | |
660 | |
579 | =back |
661 | =back |
580 | |
662 | |
581 | =head2 SUMMARY OF GENERIC WATCHER FUNCTIONS |
663 | =head2 GENERIC WATCHER FUNCTIONS |
582 | |
664 | |
583 | In the following description, C<TYPE> stands for the watcher type, |
665 | 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. |
666 | e.g. C<timer> for C<ev_timer> watchers and C<io> for C<ev_io> watchers. |
585 | |
667 | |
586 | =over 4 |
668 | =over 4 |
… | |
… | |
595 | which rolls both calls into one. |
677 | which rolls both calls into one. |
596 | |
678 | |
597 | You can reinitialise a watcher at any time as long as it has been stopped |
679 | 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. |
680 | (or never started) and there are no pending events outstanding. |
599 | |
681 | |
600 | The callbakc is always of type C<void (*)(ev_loop *loop, ev_TYPE *watcher, |
682 | The callback is always of type C<void (*)(ev_loop *loop, ev_TYPE *watcher, |
601 | int revents)>. |
683 | int revents)>. |
602 | |
684 | |
603 | =item C<ev_TYPE_set> (ev_TYPE *, [args]) |
685 | =item C<ev_TYPE_set> (ev_TYPE *, [args]) |
604 | |
686 | |
605 | This macro initialises the type-specific parts of a watcher. You need to |
687 | This macro initialises the type-specific parts of a watcher. You need to |
… | |
… | |
643 | events but its callback has not yet been invoked). As long as a watcher |
725 | events but its callback has not yet been invoked). As long as a watcher |
644 | is pending (but not active) you must not call an init function on it (but |
726 | is pending (but not active) you must not call an init function on it (but |
645 | C<ev_TYPE_set> is safe) and you must make sure the watcher is available to |
727 | C<ev_TYPE_set> is safe) and you must make sure the watcher is available to |
646 | libev (e.g. you cnanot C<free ()> it). |
728 | libev (e.g. you cnanot C<free ()> it). |
647 | |
729 | |
648 | =item callback = ev_cb (ev_TYPE *watcher) |
730 | =item callback ev_cb (ev_TYPE *watcher) |
649 | |
731 | |
650 | Returns the callback currently set on the watcher. |
732 | Returns the callback currently set on the watcher. |
651 | |
733 | |
652 | =item ev_cb_set (ev_TYPE *watcher, callback) |
734 | =item ev_cb_set (ev_TYPE *watcher, callback) |
653 | |
735 | |
… | |
… | |
681 | { |
763 | { |
682 | struct my_io *w = (struct my_io *)w_; |
764 | struct my_io *w = (struct my_io *)w_; |
683 | ... |
765 | ... |
684 | } |
766 | } |
685 | |
767 | |
686 | More interesting and less C-conformant ways of catsing your callback type |
768 | More interesting and less C-conformant ways of casting your callback type |
687 | have been omitted.... |
769 | instead have been omitted. |
|
|
770 | |
|
|
771 | Another common scenario is having some data structure with multiple |
|
|
772 | watchers: |
|
|
773 | |
|
|
774 | struct my_biggy |
|
|
775 | { |
|
|
776 | int some_data; |
|
|
777 | ev_timer t1; |
|
|
778 | ev_timer t2; |
|
|
779 | } |
|
|
780 | |
|
|
781 | In this case getting the pointer to C<my_biggy> is a bit more complicated, |
|
|
782 | you need to use C<offsetof>: |
|
|
783 | |
|
|
784 | #include <stddef.h> |
|
|
785 | |
|
|
786 | static void |
|
|
787 | t1_cb (EV_P_ struct ev_timer *w, int revents) |
|
|
788 | { |
|
|
789 | struct my_biggy big = (struct my_biggy * |
|
|
790 | (((char *)w) - offsetof (struct my_biggy, t1)); |
|
|
791 | } |
|
|
792 | |
|
|
793 | static void |
|
|
794 | t2_cb (EV_P_ struct ev_timer *w, int revents) |
|
|
795 | { |
|
|
796 | struct my_biggy big = (struct my_biggy * |
|
|
797 | (((char *)w) - offsetof (struct my_biggy, t2)); |
|
|
798 | } |
688 | |
799 | |
689 | |
800 | |
690 | =head1 WATCHER TYPES |
801 | =head1 WATCHER TYPES |
691 | |
802 | |
692 | This section describes each watcher in detail, but will not repeat |
803 | This section describes each watcher in detail, but will not repeat |
693 | information given in the last section. |
804 | information given in the last section. Any initialisation/set macros, |
|
|
805 | functions and members specific to the watcher type are explained. |
694 | |
806 | |
|
|
807 | Members are additionally marked with either I<[read-only]>, meaning that, |
|
|
808 | while the watcher is active, you can look at the member and expect some |
|
|
809 | sensible content, but you must not modify it (you can modify it while the |
|
|
810 | watcher is stopped to your hearts content), or I<[read-write]>, which |
|
|
811 | means you can expect it to have some sensible content while the watcher |
|
|
812 | is active, but you can also modify it. Modifying it may not do something |
|
|
813 | sensible or take immediate effect (or do anything at all), but libev will |
|
|
814 | not crash or malfunction in any way. |
695 | |
815 | |
|
|
816 | |
696 | =head2 C<ev_io> - is this file descriptor readable or writable |
817 | =head2 C<ev_io> - is this file descriptor readable or writable? |
697 | |
818 | |
698 | I/O watchers check whether a file descriptor is readable or writable |
819 | I/O watchers check whether a file descriptor is readable or writable |
699 | in each iteration of the event loop (This behaviour is called |
820 | in each iteration of the event loop, or, more precisely, when reading |
700 | level-triggering because you keep receiving events as long as the |
821 | 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 |
822 | some data. This behaviour is called level-triggering because you keep |
702 | act on the event and neither want to receive future events). |
823 | receiving events as long as the condition persists. Remember you can stop |
|
|
824 | the watcher if you don't want to act on the event and neither want to |
|
|
825 | receive future events. |
703 | |
826 | |
704 | In general you can register as many read and/or write event watchers per |
827 | 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 |
828 | 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 |
829 | descriptors to non-blocking mode is also usually a good idea (but not |
707 | required if you know what you are doing). |
830 | required if you know what you are doing). |
708 | |
831 | |
709 | You have to be careful with dup'ed file descriptors, though. Some backends |
832 | 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 |
833 | (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 |
834 | 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 |
835 | to the same underlying file/socket/etc. description (that is, they share |
713 | the same underlying "file open"). |
836 | the same underlying "file open"). |
714 | |
837 | |
715 | If you must do this, then force the use of a known-to-be-good backend |
838 | 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 |
839 | (at the time of this writing, this includes only C<EVBACKEND_SELECT> and |
717 | C<EVBACKEND_POLL>). |
840 | C<EVBACKEND_POLL>). |
718 | |
841 | |
|
|
842 | Another thing you have to watch out for is that it is quite easy to |
|
|
843 | receive "spurious" readyness notifications, that is your callback might |
|
|
844 | be called with C<EV_READ> but a subsequent C<read>(2) will actually block |
|
|
845 | because there is no data. Not only are some backends known to create a |
|
|
846 | lot of those (for example solaris ports), it is very easy to get into |
|
|
847 | this situation even with a relatively standard program structure. Thus |
|
|
848 | it is best to always use non-blocking I/O: An extra C<read>(2) returning |
|
|
849 | C<EAGAIN> is far preferable to a program hanging until some data arrives. |
|
|
850 | |
|
|
851 | If you cannot run the fd in non-blocking mode (for example you should not |
|
|
852 | play around with an Xlib connection), then you have to seperately re-test |
|
|
853 | wether a file descriptor is really ready with a known-to-be good interface |
|
|
854 | such as poll (fortunately in our Xlib example, Xlib already does this on |
|
|
855 | its own, so its quite safe to use). |
|
|
856 | |
719 | =over 4 |
857 | =over 4 |
720 | |
858 | |
721 | =item ev_io_init (ev_io *, callback, int fd, int events) |
859 | =item ev_io_init (ev_io *, callback, int fd, int events) |
722 | |
860 | |
723 | =item ev_io_set (ev_io *, int fd, int events) |
861 | =item ev_io_set (ev_io *, int fd, int events) |
724 | |
862 | |
725 | Configures an C<ev_io> watcher. The fd is the file descriptor to rceeive |
863 | 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 | |
864 | rceeive events for and events is either C<EV_READ>, C<EV_WRITE> or |
727 | EV_WRITE> to receive the given events. |
865 | C<EV_READ | EV_WRITE> to receive the given events. |
728 | |
866 | |
729 | Please note that most of the more scalable backend mechanisms (for example |
867 | =item int fd [read-only] |
730 | epoll and solaris ports) can result in spurious readyness notifications |
868 | |
731 | for file descriptors, so you practically need to use non-blocking I/O (and |
869 | The file descriptor being watched. |
732 | treat callback invocation as hint only), or retest separately with a safe |
870 | |
733 | interface before doing I/O (XLib can do this), or force the use of either |
871 | =item int events [read-only] |
734 | C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>, which don't suffer from this |
872 | |
735 | problem. Also note that it is quite easy to have your callback invoked |
873 | The events being watched. |
736 | when the readyness condition is no longer valid even when employing |
|
|
737 | typical ways of handling events, so its a good idea to use non-blocking |
|
|
738 | I/O unconditionally. |
|
|
739 | |
874 | |
740 | =back |
875 | =back |
741 | |
876 | |
742 | Example: call C<stdin_readable_cb> when STDIN_FILENO has become, well |
877 | 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 |
878 | readable, but only once. Since it is likely line-buffered, you could |
744 | attempt to read a whole line in the callback: |
879 | attempt to read a whole line in the callback. |
745 | |
880 | |
746 | static void |
881 | static void |
747 | stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
882 | stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
748 | { |
883 | { |
749 | ev_io_stop (loop, w); |
884 | ev_io_stop (loop, w); |
… | |
… | |
756 | ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ); |
891 | ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ); |
757 | ev_io_start (loop, &stdin_readable); |
892 | ev_io_start (loop, &stdin_readable); |
758 | ev_loop (loop, 0); |
893 | ev_loop (loop, 0); |
759 | |
894 | |
760 | |
895 | |
761 | =head2 C<ev_timer> - relative and optionally recurring timeouts |
896 | =head2 C<ev_timer> - relative and optionally repeating timeouts |
762 | |
897 | |
763 | Timer watchers are simple relative timers that generate an event after a |
898 | Timer watchers are simple relative timers that generate an event after a |
764 | given time, and optionally repeating in regular intervals after that. |
899 | given time, and optionally repeating in regular intervals after that. |
765 | |
900 | |
766 | The timers are based on real time, that is, if you register an event that |
901 | The timers are based on real time, that is, if you register an event that |
… | |
… | |
801 | =item ev_timer_again (loop) |
936 | =item ev_timer_again (loop) |
802 | |
937 | |
803 | This will act as if the timer timed out and restart it again if it is |
938 | This will act as if the timer timed out and restart it again if it is |
804 | repeating. The exact semantics are: |
939 | repeating. The exact semantics are: |
805 | |
940 | |
|
|
941 | If the timer is pending, its pending status is cleared. |
|
|
942 | |
806 | If the timer is started but nonrepeating, stop it. |
943 | If the timer is started but nonrepeating, stop it (as if it timed out). |
807 | |
944 | |
808 | If the timer is repeating, either start it if necessary (with the repeat |
945 | If the timer is repeating, either start it if necessary (with the |
809 | value), or reset the running timer to the repeat value. |
946 | C<repeat> value), or reset the running timer to the C<repeat> value. |
810 | |
947 | |
811 | This sounds a bit complicated, but here is a useful and typical |
948 | 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 |
949 | example: Imagine you have a tcp connection and you want a so-called idle |
813 | timeout, that is, you want to be called when there have been, say, 60 |
950 | timeout, that is, you want to be called when there have been, say, 60 |
814 | seconds of inactivity on the socket. The easiest way to do this is to |
951 | seconds of inactivity on the socket. The easiest way to do this is to |
815 | configure an C<ev_timer> with after=repeat=60 and calling ev_timer_again each |
952 | configure an C<ev_timer> with a C<repeat> value of C<60> and then call |
816 | time you successfully read or write some data. If you go into an idle |
953 | 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 |
954 | 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. |
955 | socket, you can C<ev_timer_stop> the timer, and C<ev_timer_again> will |
|
|
956 | automatically restart it if need be. |
|
|
957 | |
|
|
958 | That means you can ignore the C<after> value and C<ev_timer_start> |
|
|
959 | altogether and only ever use the C<repeat> value and C<ev_timer_again>: |
|
|
960 | |
|
|
961 | ev_timer_init (timer, callback, 0., 5.); |
|
|
962 | ev_timer_again (loop, timer); |
|
|
963 | ... |
|
|
964 | timer->again = 17.; |
|
|
965 | ev_timer_again (loop, timer); |
|
|
966 | ... |
|
|
967 | timer->again = 10.; |
|
|
968 | ev_timer_again (loop, timer); |
|
|
969 | |
|
|
970 | This is more slightly efficient then stopping/starting the timer each time |
|
|
971 | you want to modify its timeout value. |
|
|
972 | |
|
|
973 | =item ev_tstamp repeat [read-write] |
|
|
974 | |
|
|
975 | The current C<repeat> value. Will be used each time the watcher times out |
|
|
976 | or C<ev_timer_again> is called and determines the next timeout (if any), |
|
|
977 | which is also when any modifications are taken into account. |
819 | |
978 | |
820 | =back |
979 | =back |
821 | |
980 | |
822 | Example: create a timer that fires after 60 seconds. |
981 | Example: Create a timer that fires after 60 seconds. |
823 | |
982 | |
824 | static void |
983 | static void |
825 | one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
984 | one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
826 | { |
985 | { |
827 | .. one minute over, w is actually stopped right here |
986 | .. one minute over, w is actually stopped right here |
… | |
… | |
829 | |
988 | |
830 | struct ev_timer mytimer; |
989 | struct ev_timer mytimer; |
831 | ev_timer_init (&mytimer, one_minute_cb, 60., 0.); |
990 | ev_timer_init (&mytimer, one_minute_cb, 60., 0.); |
832 | ev_timer_start (loop, &mytimer); |
991 | ev_timer_start (loop, &mytimer); |
833 | |
992 | |
834 | Example: create a timeout timer that times out after 10 seconds of |
993 | Example: Create a timeout timer that times out after 10 seconds of |
835 | inactivity. |
994 | inactivity. |
836 | |
995 | |
837 | static void |
996 | static void |
838 | timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
997 | timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents) |
839 | { |
998 | { |
… | |
… | |
848 | // and in some piece of code that gets executed on any "activity": |
1007 | // and in some piece of code that gets executed on any "activity": |
849 | // reset the timeout to start ticking again at 10 seconds |
1008 | // reset the timeout to start ticking again at 10 seconds |
850 | ev_timer_again (&mytimer); |
1009 | ev_timer_again (&mytimer); |
851 | |
1010 | |
852 | |
1011 | |
853 | =head2 C<ev_periodic> - to cron or not to cron |
1012 | =head2 C<ev_periodic> - to cron or not to cron? |
854 | |
1013 | |
855 | Periodic watchers are also timers of a kind, but they are very versatile |
1014 | Periodic watchers are also timers of a kind, but they are very versatile |
856 | (and unfortunately a bit complex). |
1015 | (and unfortunately a bit complex). |
857 | |
1016 | |
858 | Unlike C<ev_timer>'s, they are not based on real time (or relative time) |
1017 | Unlike C<ev_timer>'s, they are not based on real time (or relative time) |
… | |
… | |
950 | Simply stops and restarts the periodic watcher again. This is only useful |
1109 | Simply stops and restarts the periodic watcher again. This is only useful |
951 | when you changed some parameters or the reschedule callback would return |
1110 | 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 |
1111 | a different time than the last time it was called (e.g. in a crond like |
953 | program when the crontabs have changed). |
1112 | program when the crontabs have changed). |
954 | |
1113 | |
|
|
1114 | =item ev_tstamp interval [read-write] |
|
|
1115 | |
|
|
1116 | The current interval value. Can be modified any time, but changes only |
|
|
1117 | take effect when the periodic timer fires or C<ev_periodic_again> is being |
|
|
1118 | called. |
|
|
1119 | |
|
|
1120 | =item ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read-write] |
|
|
1121 | |
|
|
1122 | The current reschedule callback, or C<0>, if this functionality is |
|
|
1123 | switched off. Can be changed any time, but changes only take effect when |
|
|
1124 | the periodic timer fires or C<ev_periodic_again> is being called. |
|
|
1125 | |
955 | =back |
1126 | =back |
956 | |
1127 | |
957 | Example: call a callback every hour, or, more precisely, whenever the |
1128 | Example: Call a callback every hour, or, more precisely, whenever the |
958 | system clock is divisible by 3600. The callback invocation times have |
1129 | system clock is divisible by 3600. The callback invocation times have |
959 | potentially a lot of jittering, but good long-term stability. |
1130 | potentially a lot of jittering, but good long-term stability. |
960 | |
1131 | |
961 | static void |
1132 | static void |
962 | clock_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
1133 | clock_cb (struct ev_loop *loop, struct ev_io *w, int revents) |
… | |
… | |
966 | |
1137 | |
967 | struct ev_periodic hourly_tick; |
1138 | struct ev_periodic hourly_tick; |
968 | ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0); |
1139 | ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0); |
969 | ev_periodic_start (loop, &hourly_tick); |
1140 | ev_periodic_start (loop, &hourly_tick); |
970 | |
1141 | |
971 | Example: the same as above, but use a reschedule callback to do it: |
1142 | Example: The same as above, but use a reschedule callback to do it: |
972 | |
1143 | |
973 | #include <math.h> |
1144 | #include <math.h> |
974 | |
1145 | |
975 | static ev_tstamp |
1146 | static ev_tstamp |
976 | my_scheduler_cb (struct ev_periodic *w, ev_tstamp now) |
1147 | my_scheduler_cb (struct ev_periodic *w, ev_tstamp now) |
… | |
… | |
978 | return fmod (now, 3600.) + 3600.; |
1149 | return fmod (now, 3600.) + 3600.; |
979 | } |
1150 | } |
980 | |
1151 | |
981 | ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb); |
1152 | ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb); |
982 | |
1153 | |
983 | Example: call a callback every hour, starting now: |
1154 | Example: Call a callback every hour, starting now: |
984 | |
1155 | |
985 | struct ev_periodic hourly_tick; |
1156 | struct ev_periodic hourly_tick; |
986 | ev_periodic_init (&hourly_tick, clock_cb, |
1157 | ev_periodic_init (&hourly_tick, clock_cb, |
987 | fmod (ev_now (loop), 3600.), 3600., 0); |
1158 | fmod (ev_now (loop), 3600.), 3600., 0); |
988 | ev_periodic_start (loop, &hourly_tick); |
1159 | ev_periodic_start (loop, &hourly_tick); |
989 | |
1160 | |
990 | |
1161 | |
991 | =head2 C<ev_signal> - signal me when a signal gets signalled |
1162 | =head2 C<ev_signal> - signal me when a signal gets signalled! |
992 | |
1163 | |
993 | Signal watchers will trigger an event when the process receives a specific |
1164 | 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 |
1165 | 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 |
1166 | will try it's best to deliver signals synchronously, i.e. as part of the |
996 | normal event processing, like any other event. |
1167 | normal event processing, like any other event. |
… | |
… | |
1009 | =item ev_signal_set (ev_signal *, int signum) |
1180 | =item ev_signal_set (ev_signal *, int signum) |
1010 | |
1181 | |
1011 | Configures the watcher to trigger on the given signal number (usually one |
1182 | Configures the watcher to trigger on the given signal number (usually one |
1012 | of the C<SIGxxx> constants). |
1183 | of the C<SIGxxx> constants). |
1013 | |
1184 | |
|
|
1185 | =item int signum [read-only] |
|
|
1186 | |
|
|
1187 | The signal the watcher watches out for. |
|
|
1188 | |
1014 | =back |
1189 | =back |
1015 | |
1190 | |
1016 | |
1191 | |
1017 | =head2 C<ev_child> - wait for pid status changes |
1192 | =head2 C<ev_child> - watch out for process status changes |
1018 | |
1193 | |
1019 | Child watchers trigger when your process receives a SIGCHLD in response to |
1194 | 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). |
1195 | some child status changes (most typically when a child of yours dies). |
1021 | |
1196 | |
1022 | =over 4 |
1197 | =over 4 |
… | |
… | |
1030 | at the C<rstatus> member of the C<ev_child> watcher structure to see |
1205 | 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 |
1206 | 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 |
1207 | C<waitpid> documentation). The C<rpid> member contains the pid of the |
1033 | process causing the status change. |
1208 | process causing the status change. |
1034 | |
1209 | |
|
|
1210 | =item int pid [read-only] |
|
|
1211 | |
|
|
1212 | The process id this watcher watches out for, or C<0>, meaning any process id. |
|
|
1213 | |
|
|
1214 | =item int rpid [read-write] |
|
|
1215 | |
|
|
1216 | The process id that detected a status change. |
|
|
1217 | |
|
|
1218 | =item int rstatus [read-write] |
|
|
1219 | |
|
|
1220 | The process exit/trace status caused by C<rpid> (see your systems |
|
|
1221 | C<waitpid> and C<sys/wait.h> documentation for details). |
|
|
1222 | |
1035 | =back |
1223 | =back |
1036 | |
1224 | |
1037 | Example: try to exit cleanly on SIGINT and SIGTERM. |
1225 | Example: Try to exit cleanly on SIGINT and SIGTERM. |
1038 | |
1226 | |
1039 | static void |
1227 | static void |
1040 | sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) |
1228 | sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) |
1041 | { |
1229 | { |
1042 | ev_unloop (loop, EVUNLOOP_ALL); |
1230 | ev_unloop (loop, EVUNLOOP_ALL); |
… | |
… | |
1045 | struct ev_signal signal_watcher; |
1233 | struct ev_signal signal_watcher; |
1046 | ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
1234 | ev_signal_init (&signal_watcher, sigint_cb, SIGINT); |
1047 | ev_signal_start (loop, &sigint_cb); |
1235 | ev_signal_start (loop, &sigint_cb); |
1048 | |
1236 | |
1049 | |
1237 | |
|
|
1238 | =head2 C<ev_stat> - did the file attributes just change? |
|
|
1239 | |
|
|
1240 | This watches a filesystem path for attribute changes. That is, it calls |
|
|
1241 | C<stat> regularly (or when the OS says it changed) and sees if it changed |
|
|
1242 | compared to the last time, invoking the callback if it did. |
|
|
1243 | |
|
|
1244 | The path does not need to exist: changing from "path exists" to "path does |
|
|
1245 | not exist" is a status change like any other. The condition "path does |
|
|
1246 | not exist" is signified by the C<st_nlink> field being zero (which is |
|
|
1247 | otherwise always forced to be at least one) and all the other fields of |
|
|
1248 | the stat buffer having unspecified contents. |
|
|
1249 | |
|
|
1250 | The path I<should> be absolute and I<must not> end in a slash. If it is |
|
|
1251 | relative and your working directory changes, the behaviour is undefined. |
|
|
1252 | |
|
|
1253 | Since there is no standard to do this, the portable implementation simply |
|
|
1254 | calls C<stat (2)> regularly on the path to see if it changed somehow. You |
|
|
1255 | can specify a recommended polling interval for this case. If you specify |
|
|
1256 | a polling interval of C<0> (highly recommended!) then a I<suitable, |
|
|
1257 | unspecified default> value will be used (which you can expect to be around |
|
|
1258 | five seconds, although this might change dynamically). Libev will also |
|
|
1259 | impose a minimum interval which is currently around C<0.1>, but thats |
|
|
1260 | usually overkill. |
|
|
1261 | |
|
|
1262 | This watcher type is not meant for massive numbers of stat watchers, |
|
|
1263 | as even with OS-supported change notifications, this can be |
|
|
1264 | resource-intensive. |
|
|
1265 | |
|
|
1266 | At the time of this writing, only the Linux inotify interface is |
|
|
1267 | implemented (implementing kqueue support is left as an exercise for the |
|
|
1268 | reader). Inotify will be used to give hints only and should not change the |
|
|
1269 | semantics of C<ev_stat> watchers, which means that libev sometimes needs |
|
|
1270 | to fall back to regular polling again even with inotify, but changes are |
|
|
1271 | usually detected immediately, and if the file exists there will be no |
|
|
1272 | polling. |
|
|
1273 | |
|
|
1274 | =over 4 |
|
|
1275 | |
|
|
1276 | =item ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval) |
|
|
1277 | |
|
|
1278 | =item ev_stat_set (ev_stat *, const char *path, ev_tstamp interval) |
|
|
1279 | |
|
|
1280 | Configures the watcher to wait for status changes of the given |
|
|
1281 | C<path>. The C<interval> is a hint on how quickly a change is expected to |
|
|
1282 | be detected and should normally be specified as C<0> to let libev choose |
|
|
1283 | a suitable value. The memory pointed to by C<path> must point to the same |
|
|
1284 | path for as long as the watcher is active. |
|
|
1285 | |
|
|
1286 | The callback will be receive C<EV_STAT> when a change was detected, |
|
|
1287 | relative to the attributes at the time the watcher was started (or the |
|
|
1288 | last change was detected). |
|
|
1289 | |
|
|
1290 | =item ev_stat_stat (ev_stat *) |
|
|
1291 | |
|
|
1292 | Updates the stat buffer immediately with new values. If you change the |
|
|
1293 | watched path in your callback, you could call this fucntion to avoid |
|
|
1294 | detecting this change (while introducing a race condition). Can also be |
|
|
1295 | useful simply to find out the new values. |
|
|
1296 | |
|
|
1297 | =item ev_statdata attr [read-only] |
|
|
1298 | |
|
|
1299 | The most-recently detected attributes of the file. Although the type is of |
|
|
1300 | C<ev_statdata>, this is usually the (or one of the) C<struct stat> types |
|
|
1301 | suitable for your system. If the C<st_nlink> member is C<0>, then there |
|
|
1302 | was some error while C<stat>ing the file. |
|
|
1303 | |
|
|
1304 | =item ev_statdata prev [read-only] |
|
|
1305 | |
|
|
1306 | The previous attributes of the file. The callback gets invoked whenever |
|
|
1307 | C<prev> != C<attr>. |
|
|
1308 | |
|
|
1309 | =item ev_tstamp interval [read-only] |
|
|
1310 | |
|
|
1311 | The specified interval. |
|
|
1312 | |
|
|
1313 | =item const char *path [read-only] |
|
|
1314 | |
|
|
1315 | The filesystem path that is being watched. |
|
|
1316 | |
|
|
1317 | =back |
|
|
1318 | |
|
|
1319 | Example: Watch C</etc/passwd> for attribute changes. |
|
|
1320 | |
|
|
1321 | static void |
|
|
1322 | passwd_cb (struct ev_loop *loop, ev_stat *w, int revents) |
|
|
1323 | { |
|
|
1324 | /* /etc/passwd changed in some way */ |
|
|
1325 | if (w->attr.st_nlink) |
|
|
1326 | { |
|
|
1327 | printf ("passwd current size %ld\n", (long)w->attr.st_size); |
|
|
1328 | printf ("passwd current atime %ld\n", (long)w->attr.st_mtime); |
|
|
1329 | printf ("passwd current mtime %ld\n", (long)w->attr.st_mtime); |
|
|
1330 | } |
|
|
1331 | else |
|
|
1332 | /* you shalt not abuse printf for puts */ |
|
|
1333 | puts ("wow, /etc/passwd is not there, expect problems. " |
|
|
1334 | "if this is windows, they already arrived\n"); |
|
|
1335 | } |
|
|
1336 | |
|
|
1337 | ... |
|
|
1338 | ev_stat passwd; |
|
|
1339 | |
|
|
1340 | ev_stat_init (&passwd, passwd_cb, "/etc/passwd"); |
|
|
1341 | ev_stat_start (loop, &passwd); |
|
|
1342 | |
|
|
1343 | |
1050 | =head2 C<ev_idle> - when you've got nothing better to do |
1344 | =head2 C<ev_idle> - when you've got nothing better to do... |
1051 | |
1345 | |
1052 | Idle watchers trigger events when there are no other events are pending |
1346 | 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 |
1347 | (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, |
1348 | 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 |
1349 | imagine) it will not be triggered. But when your process is idle all idle |
… | |
… | |
1073 | kind. There is a C<ev_idle_set> macro, but using it is utterly pointless, |
1367 | kind. There is a C<ev_idle_set> macro, but using it is utterly pointless, |
1074 | believe me. |
1368 | believe me. |
1075 | |
1369 | |
1076 | =back |
1370 | =back |
1077 | |
1371 | |
1078 | Example: dynamically allocate an C<ev_idle>, start it, and in the |
1372 | Example: Dynamically allocate an C<ev_idle> watcher, start it, and in the |
1079 | callback, free it. Alos, use no error checking, as usual. |
1373 | callback, free it. Also, use no error checking, as usual. |
1080 | |
1374 | |
1081 | static void |
1375 | static void |
1082 | idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents) |
1376 | idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents) |
1083 | { |
1377 | { |
1084 | free (w); |
1378 | free (w); |
… | |
… | |
1089 | struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle)); |
1383 | struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle)); |
1090 | ev_idle_init (idle_watcher, idle_cb); |
1384 | ev_idle_init (idle_watcher, idle_cb); |
1091 | ev_idle_start (loop, idle_cb); |
1385 | ev_idle_start (loop, idle_cb); |
1092 | |
1386 | |
1093 | |
1387 | |
1094 | =head2 C<ev_prepare> and C<ev_check> - customise your event loop |
1388 | =head2 C<ev_prepare> and C<ev_check> - customise your event loop! |
1095 | |
1389 | |
1096 | Prepare and check watchers are usually (but not always) used in tandem: |
1390 | Prepare and check watchers are usually (but not always) used in tandem: |
1097 | prepare watchers get invoked before the process blocks and check watchers |
1391 | prepare watchers get invoked before the process blocks and check watchers |
1098 | afterwards. |
1392 | afterwards. |
1099 | |
1393 | |
|
|
1394 | You I<must not> call C<ev_loop> or similar functions that enter |
|
|
1395 | the current event loop from either C<ev_prepare> or C<ev_check> |
|
|
1396 | watchers. Other loops than the current one are fine, however. The |
|
|
1397 | rationale behind this is that you do not need to check for recursion in |
|
|
1398 | those watchers, i.e. the sequence will always be C<ev_prepare>, blocking, |
|
|
1399 | C<ev_check> so if you have one watcher of each kind they will always be |
|
|
1400 | called in pairs bracketing the blocking call. |
|
|
1401 | |
1100 | Their main purpose is to integrate other event mechanisms into libev and |
1402 | 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 |
1403 | 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 |
1404 | variable changes, implement your own watchers, integrate net-snmp or a |
1103 | coroutine library and lots more. |
1405 | coroutine library and lots more. They are also occasionally useful if |
|
|
1406 | you cache some data and want to flush it before blocking (for example, |
|
|
1407 | in X programs you might want to do an C<XFlush ()> in an C<ev_prepare> |
|
|
1408 | watcher). |
1104 | |
1409 | |
1105 | This is done by examining in each prepare call which file descriptors need |
1410 | 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 |
1411 | 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 |
1412 | 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 |
1413 | 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> |
1435 | 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. |
1436 | macros, but using them is utterly, utterly and completely pointless. |
1132 | |
1437 | |
1133 | =back |
1438 | =back |
1134 | |
1439 | |
1135 | Example: *TODO*. |
1440 | Example: To include a library such as adns, you would add IO watchers |
|
|
1441 | and a timeout watcher in a prepare handler, as required by libadns, and |
|
|
1442 | in a check watcher, destroy them and call into libadns. What follows is |
|
|
1443 | pseudo-code only of course: |
1136 | |
1444 | |
|
|
1445 | static ev_io iow [nfd]; |
|
|
1446 | static ev_timer tw; |
1137 | |
1447 | |
|
|
1448 | static void |
|
|
1449 | io_cb (ev_loop *loop, ev_io *w, int revents) |
|
|
1450 | { |
|
|
1451 | // set the relevant poll flags |
|
|
1452 | // could also call adns_processreadable etc. here |
|
|
1453 | struct pollfd *fd = (struct pollfd *)w->data; |
|
|
1454 | if (revents & EV_READ ) fd->revents |= fd->events & POLLIN; |
|
|
1455 | if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT; |
|
|
1456 | } |
|
|
1457 | |
|
|
1458 | // create io watchers for each fd and a timer before blocking |
|
|
1459 | static void |
|
|
1460 | adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) |
|
|
1461 | { |
|
|
1462 | int timeout = 3600000;truct pollfd fds [nfd]; |
|
|
1463 | // actual code will need to loop here and realloc etc. |
|
|
1464 | adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
|
|
1465 | |
|
|
1466 | /* the callback is illegal, but won't be called as we stop during check */ |
|
|
1467 | ev_timer_init (&tw, 0, timeout * 1e-3); |
|
|
1468 | ev_timer_start (loop, &tw); |
|
|
1469 | |
|
|
1470 | // create on ev_io per pollfd |
|
|
1471 | for (int i = 0; i < nfd; ++i) |
|
|
1472 | { |
|
|
1473 | ev_io_init (iow + i, io_cb, fds [i].fd, |
|
|
1474 | ((fds [i].events & POLLIN ? EV_READ : 0) |
|
|
1475 | | (fds [i].events & POLLOUT ? EV_WRITE : 0))); |
|
|
1476 | |
|
|
1477 | fds [i].revents = 0; |
|
|
1478 | iow [i].data = fds + i; |
|
|
1479 | ev_io_start (loop, iow + i); |
|
|
1480 | } |
|
|
1481 | } |
|
|
1482 | |
|
|
1483 | // stop all watchers after blocking |
|
|
1484 | static void |
|
|
1485 | adns_check_cb (ev_loop *loop, ev_check *w, int revents) |
|
|
1486 | { |
|
|
1487 | ev_timer_stop (loop, &tw); |
|
|
1488 | |
|
|
1489 | for (int i = 0; i < nfd; ++i) |
|
|
1490 | ev_io_stop (loop, iow + i); |
|
|
1491 | |
|
|
1492 | adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop)); |
|
|
1493 | } |
|
|
1494 | |
|
|
1495 | |
1138 | =head2 C<ev_embed> - when one backend isn't enough |
1496 | =head2 C<ev_embed> - when one backend isn't enough... |
1139 | |
1497 | |
1140 | This is a rather advanced watcher type that lets you embed one event loop |
1498 | 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 |
1499 | 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 |
1500 | loop, other types of watchers might be handled in a delayed or incorrect |
1143 | fashion and must not be used). |
1501 | fashion and must not be used). |
… | |
… | |
1221 | |
1579 | |
1222 | Make a single, non-blocking sweep over the embedded loop. This works |
1580 | 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 |
1581 | similarly to C<ev_loop (embedded_loop, EVLOOP_NONBLOCK)>, but in the most |
1224 | apropriate way for embedded loops. |
1582 | apropriate way for embedded loops. |
1225 | |
1583 | |
|
|
1584 | =item struct ev_loop *loop [read-only] |
|
|
1585 | |
|
|
1586 | The embedded event loop. |
|
|
1587 | |
|
|
1588 | =back |
|
|
1589 | |
|
|
1590 | |
|
|
1591 | =head2 C<ev_fork> - the audacity to resume the event loop after a fork |
|
|
1592 | |
|
|
1593 | Fork watchers are called when a C<fork ()> was detected (usually because |
|
|
1594 | whoever is a good citizen cared to tell libev about it by calling |
|
|
1595 | C<ev_default_fork> or C<ev_loop_fork>). The invocation is done before the |
|
|
1596 | event loop blocks next and before C<ev_check> watchers are being called, |
|
|
1597 | and only in the child after the fork. If whoever good citizen calling |
|
|
1598 | C<ev_default_fork> cheats and calls it in the wrong process, the fork |
|
|
1599 | handlers will be invoked, too, of course. |
|
|
1600 | |
|
|
1601 | =over 4 |
|
|
1602 | |
|
|
1603 | =item ev_fork_init (ev_signal *, callback) |
|
|
1604 | |
|
|
1605 | Initialises and configures the fork watcher - it has no parameters of any |
|
|
1606 | kind. There is a C<ev_fork_set> macro, but using it is utterly pointless, |
|
|
1607 | believe me. |
|
|
1608 | |
1226 | =back |
1609 | =back |
1227 | |
1610 | |
1228 | |
1611 | |
1229 | =head1 OTHER FUNCTIONS |
1612 | =head1 OTHER FUNCTIONS |
1230 | |
1613 | |
… | |
… | |
1392 | |
1775 | |
1393 | =item w->sweep () C<ev::embed> only |
1776 | =item w->sweep () C<ev::embed> only |
1394 | |
1777 | |
1395 | Invokes C<ev_embed_sweep>. |
1778 | Invokes C<ev_embed_sweep>. |
1396 | |
1779 | |
|
|
1780 | =item w->update () C<ev::stat> only |
|
|
1781 | |
|
|
1782 | Invokes C<ev_stat_stat>. |
|
|
1783 | |
1397 | =back |
1784 | =back |
1398 | |
1785 | |
1399 | =back |
1786 | =back |
1400 | |
1787 | |
1401 | Example: Define a class with an IO and idle watcher, start one of them in |
1788 | Example: Define a class with an IO and idle watcher, start one of them in |
… | |
… | |
1414 | idle (this, &myclass::idle_cb) |
1801 | idle (this, &myclass::idle_cb) |
1415 | { |
1802 | { |
1416 | io.start (fd, ev::READ); |
1803 | io.start (fd, ev::READ); |
1417 | } |
1804 | } |
1418 | |
1805 | |
|
|
1806 | |
|
|
1807 | =head1 MACRO MAGIC |
|
|
1808 | |
|
|
1809 | Libev can be compiled with a variety of options, the most fundemantal is |
|
|
1810 | C<EV_MULTIPLICITY>. This option determines wether (most) functions and |
|
|
1811 | callbacks have an initial C<struct ev_loop *> argument. |
|
|
1812 | |
|
|
1813 | To make it easier to write programs that cope with either variant, the |
|
|
1814 | following macros are defined: |
|
|
1815 | |
|
|
1816 | =over 4 |
|
|
1817 | |
|
|
1818 | =item C<EV_A>, C<EV_A_> |
|
|
1819 | |
|
|
1820 | This provides the loop I<argument> for functions, if one is required ("ev |
|
|
1821 | loop argument"). The C<EV_A> form is used when this is the sole argument, |
|
|
1822 | C<EV_A_> is used when other arguments are following. Example: |
|
|
1823 | |
|
|
1824 | ev_unref (EV_A); |
|
|
1825 | ev_timer_add (EV_A_ watcher); |
|
|
1826 | ev_loop (EV_A_ 0); |
|
|
1827 | |
|
|
1828 | It assumes the variable C<loop> of type C<struct ev_loop *> is in scope, |
|
|
1829 | which is often provided by the following macro. |
|
|
1830 | |
|
|
1831 | =item C<EV_P>, C<EV_P_> |
|
|
1832 | |
|
|
1833 | This provides the loop I<parameter> for functions, if one is required ("ev |
|
|
1834 | loop parameter"). The C<EV_P> form is used when this is the sole parameter, |
|
|
1835 | C<EV_P_> is used when other parameters are following. Example: |
|
|
1836 | |
|
|
1837 | // this is how ev_unref is being declared |
|
|
1838 | static void ev_unref (EV_P); |
|
|
1839 | |
|
|
1840 | // this is how you can declare your typical callback |
|
|
1841 | static void cb (EV_P_ ev_timer *w, int revents) |
|
|
1842 | |
|
|
1843 | It declares a parameter C<loop> of type C<struct ev_loop *>, quite |
|
|
1844 | suitable for use with C<EV_A>. |
|
|
1845 | |
|
|
1846 | =item C<EV_DEFAULT>, C<EV_DEFAULT_> |
|
|
1847 | |
|
|
1848 | Similar to the other two macros, this gives you the value of the default |
|
|
1849 | loop, if multiple loops are supported ("ev loop default"). |
|
|
1850 | |
|
|
1851 | =back |
|
|
1852 | |
|
|
1853 | Example: Declare and initialise a check watcher, utilising the above |
|
|
1854 | macros so it will work regardless of wether multiple loops are supported |
|
|
1855 | or not. |
|
|
1856 | |
|
|
1857 | static void |
|
|
1858 | check_cb (EV_P_ ev_timer *w, int revents) |
|
|
1859 | { |
|
|
1860 | ev_check_stop (EV_A_ w); |
|
|
1861 | } |
|
|
1862 | |
|
|
1863 | ev_check check; |
|
|
1864 | ev_check_init (&check, check_cb); |
|
|
1865 | ev_check_start (EV_DEFAULT_ &check); |
|
|
1866 | ev_loop (EV_DEFAULT_ 0); |
|
|
1867 | |
|
|
1868 | =head1 EMBEDDING |
|
|
1869 | |
|
|
1870 | Libev can (and often is) directly embedded into host |
|
|
1871 | applications. Examples of applications that embed it include the Deliantra |
|
|
1872 | Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe) |
|
|
1873 | and rxvt-unicode. |
|
|
1874 | |
|
|
1875 | The goal is to enable you to just copy the neecssary files into your |
|
|
1876 | source directory without having to change even a single line in them, so |
|
|
1877 | you can easily upgrade by simply copying (or having a checked-out copy of |
|
|
1878 | libev somewhere in your source tree). |
|
|
1879 | |
|
|
1880 | =head2 FILESETS |
|
|
1881 | |
|
|
1882 | Depending on what features you need you need to include one or more sets of files |
|
|
1883 | in your app. |
|
|
1884 | |
|
|
1885 | =head3 CORE EVENT LOOP |
|
|
1886 | |
|
|
1887 | To include only the libev core (all the C<ev_*> functions), with manual |
|
|
1888 | configuration (no autoconf): |
|
|
1889 | |
|
|
1890 | #define EV_STANDALONE 1 |
|
|
1891 | #include "ev.c" |
|
|
1892 | |
|
|
1893 | This will automatically include F<ev.h>, too, and should be done in a |
|
|
1894 | single C source file only to provide the function implementations. To use |
|
|
1895 | it, do the same for F<ev.h> in all files wishing to use this API (best |
|
|
1896 | done by writing a wrapper around F<ev.h> that you can include instead and |
|
|
1897 | where you can put other configuration options): |
|
|
1898 | |
|
|
1899 | #define EV_STANDALONE 1 |
|
|
1900 | #include "ev.h" |
|
|
1901 | |
|
|
1902 | Both header files and implementation files can be compiled with a C++ |
|
|
1903 | compiler (at least, thats a stated goal, and breakage will be treated |
|
|
1904 | as a bug). |
|
|
1905 | |
|
|
1906 | You need the following files in your source tree, or in a directory |
|
|
1907 | in your include path (e.g. in libev/ when using -Ilibev): |
|
|
1908 | |
|
|
1909 | ev.h |
|
|
1910 | ev.c |
|
|
1911 | ev_vars.h |
|
|
1912 | ev_wrap.h |
|
|
1913 | |
|
|
1914 | ev_win32.c required on win32 platforms only |
|
|
1915 | |
|
|
1916 | ev_select.c only when select backend is enabled (which is enabled by default) |
|
|
1917 | ev_poll.c only when poll backend is enabled (disabled by default) |
|
|
1918 | ev_epoll.c only when the epoll backend is enabled (disabled by default) |
|
|
1919 | ev_kqueue.c only when the kqueue backend is enabled (disabled by default) |
|
|
1920 | ev_port.c only when the solaris port backend is enabled (disabled by default) |
|
|
1921 | |
|
|
1922 | F<ev.c> includes the backend files directly when enabled, so you only need |
|
|
1923 | to compile this single file. |
|
|
1924 | |
|
|
1925 | =head3 LIBEVENT COMPATIBILITY API |
|
|
1926 | |
|
|
1927 | To include the libevent compatibility API, also include: |
|
|
1928 | |
|
|
1929 | #include "event.c" |
|
|
1930 | |
|
|
1931 | in the file including F<ev.c>, and: |
|
|
1932 | |
|
|
1933 | #include "event.h" |
|
|
1934 | |
|
|
1935 | in the files that want to use the libevent API. This also includes F<ev.h>. |
|
|
1936 | |
|
|
1937 | You need the following additional files for this: |
|
|
1938 | |
|
|
1939 | event.h |
|
|
1940 | event.c |
|
|
1941 | |
|
|
1942 | =head3 AUTOCONF SUPPORT |
|
|
1943 | |
|
|
1944 | Instead of using C<EV_STANDALONE=1> and providing your config in |
|
|
1945 | whatever way you want, you can also C<m4_include([libev.m4])> in your |
|
|
1946 | F<configure.ac> and leave C<EV_STANDALONE> undefined. F<ev.c> will then |
|
|
1947 | include F<config.h> and configure itself accordingly. |
|
|
1948 | |
|
|
1949 | For this of course you need the m4 file: |
|
|
1950 | |
|
|
1951 | libev.m4 |
|
|
1952 | |
|
|
1953 | =head2 PREPROCESSOR SYMBOLS/MACROS |
|
|
1954 | |
|
|
1955 | Libev can be configured via a variety of preprocessor symbols you have to define |
|
|
1956 | before including any of its files. The default is not to build for multiplicity |
|
|
1957 | and only include the select backend. |
|
|
1958 | |
|
|
1959 | =over 4 |
|
|
1960 | |
|
|
1961 | =item EV_STANDALONE |
|
|
1962 | |
|
|
1963 | Must always be C<1> if you do not use autoconf configuration, which |
|
|
1964 | keeps libev from including F<config.h>, and it also defines dummy |
|
|
1965 | implementations for some libevent functions (such as logging, which is not |
|
|
1966 | supported). It will also not define any of the structs usually found in |
|
|
1967 | F<event.h> that are not directly supported by the libev core alone. |
|
|
1968 | |
|
|
1969 | =item EV_USE_MONOTONIC |
|
|
1970 | |
|
|
1971 | If defined to be C<1>, libev will try to detect the availability of the |
|
|
1972 | monotonic clock option at both compiletime and runtime. Otherwise no use |
|
|
1973 | of the monotonic clock option will be attempted. If you enable this, you |
|
|
1974 | usually have to link against librt or something similar. Enabling it when |
|
|
1975 | the functionality isn't available is safe, though, althoguh you have |
|
|
1976 | to make sure you link against any libraries where the C<clock_gettime> |
|
|
1977 | function is hiding in (often F<-lrt>). |
|
|
1978 | |
|
|
1979 | =item EV_USE_REALTIME |
|
|
1980 | |
|
|
1981 | If defined to be C<1>, libev will try to detect the availability of the |
|
|
1982 | realtime clock option at compiletime (and assume its availability at |
|
|
1983 | runtime if successful). Otherwise no use of the realtime clock option will |
|
|
1984 | be attempted. This effectively replaces C<gettimeofday> by C<clock_get |
|
|
1985 | (CLOCK_REALTIME, ...)> and will not normally affect correctness. See tzhe note about libraries |
|
|
1986 | in the description of C<EV_USE_MONOTONIC>, though. |
|
|
1987 | |
|
|
1988 | =item EV_USE_SELECT |
|
|
1989 | |
|
|
1990 | If undefined or defined to be C<1>, libev will compile in support for the |
|
|
1991 | C<select>(2) backend. No attempt at autodetection will be done: if no |
|
|
1992 | other method takes over, select will be it. Otherwise the select backend |
|
|
1993 | will not be compiled in. |
|
|
1994 | |
|
|
1995 | =item EV_SELECT_USE_FD_SET |
|
|
1996 | |
|
|
1997 | If defined to C<1>, then the select backend will use the system C<fd_set> |
|
|
1998 | structure. This is useful if libev doesn't compile due to a missing |
|
|
1999 | C<NFDBITS> or C<fd_mask> definition or it misguesses the bitset layout on |
|
|
2000 | exotic systems. This usually limits the range of file descriptors to some |
|
|
2001 | low limit such as 1024 or might have other limitations (winsocket only |
|
|
2002 | allows 64 sockets). The C<FD_SETSIZE> macro, set before compilation, might |
|
|
2003 | influence the size of the C<fd_set> used. |
|
|
2004 | |
|
|
2005 | =item EV_SELECT_IS_WINSOCKET |
|
|
2006 | |
|
|
2007 | When defined to C<1>, the select backend will assume that |
|
|
2008 | select/socket/connect etc. don't understand file descriptors but |
|
|
2009 | wants osf handles on win32 (this is the case when the select to |
|
|
2010 | be used is the winsock select). This means that it will call |
|
|
2011 | C<_get_osfhandle> on the fd to convert it to an OS handle. Otherwise, |
|
|
2012 | it is assumed that all these functions actually work on fds, even |
|
|
2013 | on win32. Should not be defined on non-win32 platforms. |
|
|
2014 | |
|
|
2015 | =item EV_USE_POLL |
|
|
2016 | |
|
|
2017 | If defined to be C<1>, libev will compile in support for the C<poll>(2) |
|
|
2018 | backend. Otherwise it will be enabled on non-win32 platforms. It |
|
|
2019 | takes precedence over select. |
|
|
2020 | |
|
|
2021 | =item EV_USE_EPOLL |
|
|
2022 | |
|
|
2023 | If defined to be C<1>, libev will compile in support for the Linux |
|
|
2024 | C<epoll>(7) backend. Its availability will be detected at runtime, |
|
|
2025 | otherwise another method will be used as fallback. This is the |
|
|
2026 | preferred backend for GNU/Linux systems. |
|
|
2027 | |
|
|
2028 | =item EV_USE_KQUEUE |
|
|
2029 | |
|
|
2030 | If defined to be C<1>, libev will compile in support for the BSD style |
|
|
2031 | C<kqueue>(2) backend. Its actual availability will be detected at runtime, |
|
|
2032 | otherwise another method will be used as fallback. This is the preferred |
|
|
2033 | backend for BSD and BSD-like systems, although on most BSDs kqueue only |
|
|
2034 | supports some types of fds correctly (the only platform we found that |
|
|
2035 | supports ptys for example was NetBSD), so kqueue might be compiled in, but |
|
|
2036 | not be used unless explicitly requested. The best way to use it is to find |
|
|
2037 | out whether kqueue supports your type of fd properly and use an embedded |
|
|
2038 | kqueue loop. |
|
|
2039 | |
|
|
2040 | =item EV_USE_PORT |
|
|
2041 | |
|
|
2042 | If defined to be C<1>, libev will compile in support for the Solaris |
|
|
2043 | 10 port style backend. Its availability will be detected at runtime, |
|
|
2044 | otherwise another method will be used as fallback. This is the preferred |
|
|
2045 | backend for Solaris 10 systems. |
|
|
2046 | |
|
|
2047 | =item EV_USE_DEVPOLL |
|
|
2048 | |
|
|
2049 | reserved for future expansion, works like the USE symbols above. |
|
|
2050 | |
|
|
2051 | =item EV_USE_INOTIFY |
|
|
2052 | |
|
|
2053 | If defined to be C<1>, libev will compile in support for the Linux inotify |
|
|
2054 | interface to speed up C<ev_stat> watchers. Its actual availability will |
|
|
2055 | be detected at runtime. |
|
|
2056 | |
|
|
2057 | =item EV_H |
|
|
2058 | |
|
|
2059 | The name of the F<ev.h> header file used to include it. The default if |
|
|
2060 | undefined is C<< <ev.h> >> in F<event.h> and C<"ev.h"> in F<ev.c>. This |
|
|
2061 | can be used to virtually rename the F<ev.h> header file in case of conflicts. |
|
|
2062 | |
|
|
2063 | =item EV_CONFIG_H |
|
|
2064 | |
|
|
2065 | If C<EV_STANDALONE> isn't C<1>, this variable can be used to override |
|
|
2066 | F<ev.c>'s idea of where to find the F<config.h> file, similarly to |
|
|
2067 | C<EV_H>, above. |
|
|
2068 | |
|
|
2069 | =item EV_EVENT_H |
|
|
2070 | |
|
|
2071 | Similarly to C<EV_H>, this macro can be used to override F<event.c>'s idea |
|
|
2072 | of how the F<event.h> header can be found. |
|
|
2073 | |
|
|
2074 | =item EV_PROTOTYPES |
|
|
2075 | |
|
|
2076 | If defined to be C<0>, then F<ev.h> will not define any function |
|
|
2077 | prototypes, but still define all the structs and other symbols. This is |
|
|
2078 | occasionally useful if you want to provide your own wrapper functions |
|
|
2079 | around libev functions. |
|
|
2080 | |
|
|
2081 | =item EV_MULTIPLICITY |
|
|
2082 | |
|
|
2083 | If undefined or defined to C<1>, then all event-loop-specific functions |
|
|
2084 | will have the C<struct ev_loop *> as first argument, and you can create |
|
|
2085 | additional independent event loops. Otherwise there will be no support |
|
|
2086 | for multiple event loops and there is no first event loop pointer |
|
|
2087 | argument. Instead, all functions act on the single default loop. |
|
|
2088 | |
|
|
2089 | =item EV_PERIODIC_ENABLE |
|
|
2090 | |
|
|
2091 | If undefined or defined to be C<1>, then periodic timers are supported. If |
|
|
2092 | defined to be C<0>, then they are not. Disabling them saves a few kB of |
|
|
2093 | code. |
|
|
2094 | |
|
|
2095 | =item EV_EMBED_ENABLE |
|
|
2096 | |
|
|
2097 | If undefined or defined to be C<1>, then embed watchers are supported. If |
|
|
2098 | defined to be C<0>, then they are not. |
|
|
2099 | |
|
|
2100 | =item EV_STAT_ENABLE |
|
|
2101 | |
|
|
2102 | If undefined or defined to be C<1>, then stat watchers are supported. If |
|
|
2103 | defined to be C<0>, then they are not. |
|
|
2104 | |
|
|
2105 | =item EV_FORK_ENABLE |
|
|
2106 | |
|
|
2107 | If undefined or defined to be C<1>, then fork watchers are supported. If |
|
|
2108 | defined to be C<0>, then they are not. |
|
|
2109 | |
|
|
2110 | =item EV_MINIMAL |
|
|
2111 | |
|
|
2112 | If you need to shave off some kilobytes of code at the expense of some |
|
|
2113 | speed, define this symbol to C<1>. Currently only used for gcc to override |
|
|
2114 | some inlining decisions, saves roughly 30% codesize of amd64. |
|
|
2115 | |
|
|
2116 | =item EV_PID_HASHSIZE |
|
|
2117 | |
|
|
2118 | C<ev_child> watchers use a small hash table to distribute workload by |
|
|
2119 | pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more |
|
|
2120 | than enough. If you need to manage thousands of children you might want to |
|
|
2121 | increase this value (I<must> be a power of two). |
|
|
2122 | |
|
|
2123 | =item EV_INOTIFY_HASHSIZE |
|
|
2124 | |
|
|
2125 | C<ev_staz> watchers use a small hash table to distribute workload by |
|
|
2126 | inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>), |
|
|
2127 | usually more than enough. If you need to manage thousands of C<ev_stat> |
|
|
2128 | watchers you might want to increase this value (I<must> be a power of |
|
|
2129 | two). |
|
|
2130 | |
|
|
2131 | =item EV_COMMON |
|
|
2132 | |
|
|
2133 | By default, all watchers have a C<void *data> member. By redefining |
|
|
2134 | this macro to a something else you can include more and other types of |
|
|
2135 | members. You have to define it each time you include one of the files, |
|
|
2136 | though, and it must be identical each time. |
|
|
2137 | |
|
|
2138 | For example, the perl EV module uses something like this: |
|
|
2139 | |
|
|
2140 | #define EV_COMMON \ |
|
|
2141 | SV *self; /* contains this struct */ \ |
|
|
2142 | SV *cb_sv, *fh /* note no trailing ";" */ |
|
|
2143 | |
|
|
2144 | =item EV_CB_DECLARE (type) |
|
|
2145 | |
|
|
2146 | =item EV_CB_INVOKE (watcher, revents) |
|
|
2147 | |
|
|
2148 | =item ev_set_cb (ev, cb) |
|
|
2149 | |
|
|
2150 | Can be used to change the callback member declaration in each watcher, |
|
|
2151 | and the way callbacks are invoked and set. Must expand to a struct member |
|
|
2152 | definition and a statement, respectively. See the F<ev.v> header file for |
|
|
2153 | their default definitions. One possible use for overriding these is to |
|
|
2154 | avoid the C<struct ev_loop *> as first argument in all cases, or to use |
|
|
2155 | method calls instead of plain function calls in C++. |
|
|
2156 | |
|
|
2157 | =head2 EXAMPLES |
|
|
2158 | |
|
|
2159 | For a real-world example of a program the includes libev |
|
|
2160 | verbatim, you can have a look at the EV perl module |
|
|
2161 | (L<http://software.schmorp.de/pkg/EV.html>). It has the libev files in |
|
|
2162 | the F<libev/> subdirectory and includes them in the F<EV/EVAPI.h> (public |
|
|
2163 | interface) and F<EV.xs> (implementation) files. Only the F<EV.xs> file |
|
|
2164 | will be compiled. It is pretty complex because it provides its own header |
|
|
2165 | file. |
|
|
2166 | |
|
|
2167 | The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file |
|
|
2168 | that everybody includes and which overrides some configure choices: |
|
|
2169 | |
|
|
2170 | #define EV_MINIMAL 1 |
|
|
2171 | #define EV_USE_POLL 0 |
|
|
2172 | #define EV_MULTIPLICITY 0 |
|
|
2173 | #define EV_PERIODIC_ENABLE 0 |
|
|
2174 | #define EV_STAT_ENABLE 0 |
|
|
2175 | #define EV_FORK_ENABLE 0 |
|
|
2176 | #define EV_CONFIG_H <config.h> |
|
|
2177 | #define EV_MINPRI 0 |
|
|
2178 | #define EV_MAXPRI 0 |
|
|
2179 | |
|
|
2180 | #include "ev++.h" |
|
|
2181 | |
|
|
2182 | And a F<ev_cpp.C> implementation file that contains libev proper and is compiled: |
|
|
2183 | |
|
|
2184 | #include "ev_cpp.h" |
|
|
2185 | #include "ev.c" |
|
|
2186 | |
|
|
2187 | |
|
|
2188 | =head1 COMPLEXITIES |
|
|
2189 | |
|
|
2190 | In this section the complexities of (many of) the algorithms used inside |
|
|
2191 | libev will be explained. For complexity discussions about backends see the |
|
|
2192 | documentation for C<ev_default_init>. |
|
|
2193 | |
|
|
2194 | =over 4 |
|
|
2195 | |
|
|
2196 | =item Starting and stopping timer/periodic watchers: O(log skipped_other_timers) |
|
|
2197 | |
|
|
2198 | =item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers) |
|
|
2199 | |
|
|
2200 | =item Starting io/check/prepare/idle/signal/child watchers: O(1) |
|
|
2201 | |
|
|
2202 | =item Stopping check/prepare/idle watchers: O(1) |
|
|
2203 | |
|
|
2204 | =item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE)) |
|
|
2205 | |
|
|
2206 | =item Finding the next timer per loop iteration: O(1) |
|
|
2207 | |
|
|
2208 | =item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd) |
|
|
2209 | |
|
|
2210 | =item Activating one watcher: O(1) |
|
|
2211 | |
|
|
2212 | =back |
|
|
2213 | |
|
|
2214 | |
1419 | =head1 AUTHOR |
2215 | =head1 AUTHOR |
1420 | |
2216 | |
1421 | Marc Lehmann <libev@schmorp.de>. |
2217 | Marc Lehmann <libev@schmorp.de>. |
1422 | |
2218 | |