… | |
… | |
47 | |
47 | |
48 | return 0; |
48 | return 0; |
49 | } |
49 | } |
50 | |
50 | |
51 | =head1 DESCRIPTION |
51 | =head1 DESCRIPTION |
|
|
52 | |
|
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53 | The newest version of this document is also available as a html-formatted |
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54 | web page you might find easier to navigate when reading it for the first |
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55 | time: L<http://cvs.schmorp.de/libev/ev.html>. |
52 | |
56 | |
53 | Libev is an event loop: you register interest in certain events (such as a |
57 | Libev is an event loop: you register interest in certain events (such as a |
54 | file descriptor being readable or a timeout occuring), and it will manage |
58 | file descriptor being readable or a timeout occuring), and it will manage |
55 | these event sources and provide your program with events. |
59 | these event sources and provide your program with events. |
56 | |
60 | |
… | |
… | |
94 | Libev represents time as a single floating point number, representing the |
98 | Libev represents time as a single floating point number, representing the |
95 | (fractional) number of seconds since the (POSIX) epoch (somewhere near |
99 | (fractional) number of seconds since the (POSIX) epoch (somewhere near |
96 | the beginning of 1970, details are complicated, don't ask). This type is |
100 | the beginning of 1970, details are complicated, don't ask). This type is |
97 | called C<ev_tstamp>, which is what you should use too. It usually aliases |
101 | called C<ev_tstamp>, which is what you should use too. It usually aliases |
98 | to the C<double> type in C, and when you need to do any calculations on |
102 | to the C<double> type in C, and when you need to do any calculations on |
99 | it, you should treat it as such. |
103 | it, you should treat it as some floatingpoint value. Unlike the name |
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104 | component C<stamp> might indicate, it is also used for time differences |
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105 | throughout libev. |
100 | |
106 | |
101 | =head1 GLOBAL FUNCTIONS |
107 | =head1 GLOBAL FUNCTIONS |
102 | |
108 | |
103 | These functions can be called anytime, even before initialising the |
109 | These functions can be called anytime, even before initialising the |
104 | library in any way. |
110 | library in any way. |
… | |
… | |
113 | |
119 | |
114 | =item int ev_version_major () |
120 | =item int ev_version_major () |
115 | |
121 | |
116 | =item int ev_version_minor () |
122 | =item int ev_version_minor () |
117 | |
123 | |
118 | You can find out the major and minor version numbers of the library |
124 | You can find out the major and minor ABI version numbers of the library |
119 | you linked against by calling the functions C<ev_version_major> and |
125 | you linked against by calling the functions C<ev_version_major> and |
120 | C<ev_version_minor>. If you want, you can compare against the global |
126 | C<ev_version_minor>. If you want, you can compare against the global |
121 | symbols C<EV_VERSION_MAJOR> and C<EV_VERSION_MINOR>, which specify the |
127 | symbols C<EV_VERSION_MAJOR> and C<EV_VERSION_MINOR>, which specify the |
122 | version of the library your program was compiled against. |
128 | version of the library your program was compiled against. |
123 | |
129 | |
|
|
130 | These version numbers refer to the ABI version of the library, not the |
|
|
131 | release version. |
|
|
132 | |
124 | Usually, it's a good idea to terminate if the major versions mismatch, |
133 | Usually, it's a good idea to terminate if the major versions mismatch, |
125 | as this indicates an incompatible change. Minor versions are usually |
134 | as this indicates an incompatible change. Minor versions are usually |
126 | compatible to older versions, so a larger minor version alone is usually |
135 | compatible to older versions, so a larger minor version alone is usually |
127 | not a problem. |
136 | not a problem. |
128 | |
137 | |
129 | Example: Make sure we haven't accidentally been linked against the wrong |
138 | Example: Make sure we haven't accidentally been linked against the wrong |
130 | version. |
139 | version. |
… | |
… | |
266 | C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will |
275 | C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will |
267 | override the flags completely if it is found in the environment. This is |
276 | override the flags completely if it is found in the environment. This is |
268 | useful to try out specific backends to test their performance, or to work |
277 | useful to try out specific backends to test their performance, or to work |
269 | around bugs. |
278 | around bugs. |
270 | |
279 | |
|
|
280 | =item C<EVFLAG_FORKCHECK> |
|
|
281 | |
|
|
282 | Instead of calling C<ev_default_fork> or C<ev_loop_fork> manually after |
|
|
283 | a fork, you can also make libev check for a fork in each iteration by |
|
|
284 | enabling this flag. |
|
|
285 | |
|
|
286 | This works by calling C<getpid ()> on every iteration of the loop, |
|
|
287 | and thus this might slow down your event loop if you do a lot of loop |
|
|
288 | iterations and little real work, but is usually not noticeable (on my |
|
|
289 | Linux system for example, C<getpid> is actually a simple 5-insn sequence |
|
|
290 | without a syscall and thus I<very> fast, but my Linux system also has |
|
|
291 | C<pthread_atfork> which is even faster). |
|
|
292 | |
|
|
293 | The big advantage of this flag is that you can forget about fork (and |
|
|
294 | forget about forgetting to tell libev about forking) when you use this |
|
|
295 | flag. |
|
|
296 | |
|
|
297 | This flag setting cannot be overriden or specified in the C<LIBEV_FLAGS> |
|
|
298 | environment variable. |
|
|
299 | |
271 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
300 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
272 | |
301 | |
273 | This is your standard select(2) backend. Not I<completely> standard, as |
302 | This is your standard select(2) backend. Not I<completely> standard, as |
274 | libev tries to roll its own fd_set with no limits on the number of fds, |
303 | libev tries to roll its own fd_set with no limits on the number of fds, |
275 | but if that fails, expect a fairly low limit on the number of fds when |
304 | but if that fails, expect a fairly low limit on the number of fds when |
… | |
… | |
375 | Destroys the default loop again (frees all memory and kernel state |
404 | Destroys the default loop again (frees all memory and kernel state |
376 | etc.). None of the active event watchers will be stopped in the normal |
405 | etc.). None of the active event watchers will be stopped in the normal |
377 | sense, so e.g. C<ev_is_active> might still return true. It is your |
406 | sense, so e.g. C<ev_is_active> might still return true. It is your |
378 | responsibility to either stop all watchers cleanly yoursef I<before> |
407 | responsibility to either stop all watchers cleanly yoursef I<before> |
379 | calling this function, or cope with the fact afterwards (which is usually |
408 | calling this function, or cope with the fact afterwards (which is usually |
380 | the easiest thing, youc na just ignore the watchers and/or C<free ()> them |
409 | the easiest thing, you can just ignore the watchers and/or C<free ()> them |
381 | for example). |
410 | for example). |
|
|
411 | |
|
|
412 | Note that certain global state, such as signal state, will not be freed by |
|
|
413 | this function, and related watchers (such as signal and child watchers) |
|
|
414 | would need to be stopped manually. |
|
|
415 | |
|
|
416 | In general it is not advisable to call this function except in the |
|
|
417 | rare occasion where you really need to free e.g. the signal handling |
|
|
418 | pipe fds. If you need dynamically allocated loops it is better to use |
|
|
419 | C<ev_loop_new> and C<ev_loop_destroy>). |
382 | |
420 | |
383 | =item ev_loop_destroy (loop) |
421 | =item ev_loop_destroy (loop) |
384 | |
422 | |
385 | Like C<ev_default_destroy>, but destroys an event loop created by an |
423 | Like C<ev_default_destroy>, but destroys an event loop created by an |
386 | earlier call to C<ev_loop_new>. |
424 | earlier call to C<ev_loop_new>. |
… | |
… | |
409 | =item ev_loop_fork (loop) |
447 | =item ev_loop_fork (loop) |
410 | |
448 | |
411 | Like C<ev_default_fork>, but acts on an event loop created by |
449 | Like C<ev_default_fork>, but acts on an event loop created by |
412 | C<ev_loop_new>. Yes, you have to call this on every allocated event loop |
450 | C<ev_loop_new>. Yes, you have to call this on every allocated event loop |
413 | after fork, and how you do this is entirely your own problem. |
451 | after fork, and how you do this is entirely your own problem. |
|
|
452 | |
|
|
453 | =item unsigned int ev_loop_count (loop) |
|
|
454 | |
|
|
455 | Returns the count of loop iterations for the loop, which is identical to |
|
|
456 | the number of times libev did poll for new events. It starts at C<0> and |
|
|
457 | happily wraps around with enough iterations. |
|
|
458 | |
|
|
459 | This value can sometimes be useful as a generation counter of sorts (it |
|
|
460 | "ticks" the number of loop iterations), as it roughly corresponds with |
|
|
461 | C<ev_prepare> and C<ev_check> calls. |
414 | |
462 | |
415 | =item unsigned int ev_backend (loop) |
463 | =item unsigned int ev_backend (loop) |
416 | |
464 | |
417 | Returns one of the C<EVBACKEND_*> flags indicating the event backend in |
465 | Returns one of the C<EVBACKEND_*> flags indicating the event backend in |
418 | use. |
466 | use. |
… | |
… | |
452 | libev watchers. However, a pair of C<ev_prepare>/C<ev_check> watchers is |
500 | libev watchers. However, a pair of C<ev_prepare>/C<ev_check> watchers is |
453 | usually a better approach for this kind of thing. |
501 | usually a better approach for this kind of thing. |
454 | |
502 | |
455 | Here are the gory details of what C<ev_loop> does: |
503 | Here are the gory details of what C<ev_loop> does: |
456 | |
504 | |
|
|
505 | - Before the first iteration, call any pending watchers. |
457 | * If there are no active watchers (reference count is zero), return. |
506 | * If there are no active watchers (reference count is zero), return. |
458 | - Queue prepare watchers and then call all outstanding watchers. |
507 | - Queue all prepare watchers and then call all outstanding watchers. |
459 | - If we have been forked, recreate the kernel state. |
508 | - If we have been forked, recreate the kernel state. |
460 | - Update the kernel state with all outstanding changes. |
509 | - Update the kernel state with all outstanding changes. |
461 | - Update the "event loop time". |
510 | - Update the "event loop time". |
462 | - Calculate for how long to block. |
511 | - Calculate for how long to block. |
463 | - Block the process, waiting for any events. |
512 | - Block the process, waiting for any events. |
… | |
… | |
702 | =item bool ev_is_pending (ev_TYPE *watcher) |
751 | =item bool ev_is_pending (ev_TYPE *watcher) |
703 | |
752 | |
704 | Returns a true value iff the watcher is pending, (i.e. it has outstanding |
753 | Returns a true value iff the watcher is pending, (i.e. it has outstanding |
705 | events but its callback has not yet been invoked). As long as a watcher |
754 | events but its callback has not yet been invoked). As long as a watcher |
706 | is pending (but not active) you must not call an init function on it (but |
755 | is pending (but not active) you must not call an init function on it (but |
707 | C<ev_TYPE_set> is safe) and you must make sure the watcher is available to |
756 | C<ev_TYPE_set> is safe), you must not change its priority, and you must |
708 | libev (e.g. you cnanot C<free ()> it). |
757 | make sure the watcher is available to libev (e.g. you cannot C<free ()> |
|
|
758 | it). |
709 | |
759 | |
710 | =item callback ev_cb (ev_TYPE *watcher) |
760 | =item callback ev_cb (ev_TYPE *watcher) |
711 | |
761 | |
712 | Returns the callback currently set on the watcher. |
762 | Returns the callback currently set on the watcher. |
713 | |
763 | |
714 | =item ev_cb_set (ev_TYPE *watcher, callback) |
764 | =item ev_cb_set (ev_TYPE *watcher, callback) |
715 | |
765 | |
716 | Change the callback. You can change the callback at virtually any time |
766 | Change the callback. You can change the callback at virtually any time |
717 | (modulo threads). |
767 | (modulo threads). |
|
|
768 | |
|
|
769 | =item ev_set_priority (ev_TYPE *watcher, priority) |
|
|
770 | |
|
|
771 | =item int ev_priority (ev_TYPE *watcher) |
|
|
772 | |
|
|
773 | Set and query the priority of the watcher. The priority is a small |
|
|
774 | integer between C<EV_MAXPRI> (default: C<2>) and C<EV_MINPRI> |
|
|
775 | (default: C<-2>). Pending watchers with higher priority will be invoked |
|
|
776 | before watchers with lower priority, but priority will not keep watchers |
|
|
777 | from being executed (except for C<ev_idle> watchers). |
|
|
778 | |
|
|
779 | This means that priorities are I<only> used for ordering callback |
|
|
780 | invocation after new events have been received. This is useful, for |
|
|
781 | example, to reduce latency after idling, or more often, to bind two |
|
|
782 | watchers on the same event and make sure one is called first. |
|
|
783 | |
|
|
784 | If you need to suppress invocation when higher priority events are pending |
|
|
785 | you need to look at C<ev_idle> watchers, which provide this functionality. |
|
|
786 | |
|
|
787 | You I<must not> change the priority of a watcher as long as it is active or |
|
|
788 | pending. |
|
|
789 | |
|
|
790 | The default priority used by watchers when no priority has been set is |
|
|
791 | always C<0>, which is supposed to not be too high and not be too low :). |
|
|
792 | |
|
|
793 | Setting a priority outside the range of C<EV_MINPRI> to C<EV_MAXPRI> is |
|
|
794 | fine, as long as you do not mind that the priority value you query might |
|
|
795 | or might not have been adjusted to be within valid range. |
|
|
796 | |
|
|
797 | =item ev_invoke (loop, ev_TYPE *watcher, int revents) |
|
|
798 | |
|
|
799 | Invoke the C<watcher> with the given C<loop> and C<revents>. Neither |
|
|
800 | C<loop> nor C<revents> need to be valid as long as the watcher callback |
|
|
801 | can deal with that fact. |
|
|
802 | |
|
|
803 | =item int ev_clear_pending (loop, ev_TYPE *watcher) |
|
|
804 | |
|
|
805 | If the watcher is pending, this function returns clears its pending status |
|
|
806 | and returns its C<revents> bitset (as if its callback was invoked). If the |
|
|
807 | watcher isn't pending it does nothing and returns C<0>. |
718 | |
808 | |
719 | =back |
809 | =back |
720 | |
810 | |
721 | |
811 | |
722 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
812 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
… | |
… | |
828 | it is best to always use non-blocking I/O: An extra C<read>(2) returning |
918 | it is best to always use non-blocking I/O: An extra C<read>(2) returning |
829 | C<EAGAIN> is far preferable to a program hanging until some data arrives. |
919 | C<EAGAIN> is far preferable to a program hanging until some data arrives. |
830 | |
920 | |
831 | If you cannot run the fd in non-blocking mode (for example you should not |
921 | If you cannot run the fd in non-blocking mode (for example you should not |
832 | play around with an Xlib connection), then you have to seperately re-test |
922 | play around with an Xlib connection), then you have to seperately re-test |
833 | wether a file descriptor is really ready with a known-to-be good interface |
923 | whether a file descriptor is really ready with a known-to-be good interface |
834 | such as poll (fortunately in our Xlib example, Xlib already does this on |
924 | such as poll (fortunately in our Xlib example, Xlib already does this on |
835 | its own, so its quite safe to use). |
925 | its own, so its quite safe to use). |
|
|
926 | |
|
|
927 | =head3 The special problem of disappearing file descriptors |
|
|
928 | |
|
|
929 | Some backends (e.g kqueue, epoll) need to be told about closing a file |
|
|
930 | descriptor (either by calling C<close> explicitly or by any other means, |
|
|
931 | such as C<dup>). The reason is that you register interest in some file |
|
|
932 | descriptor, but when it goes away, the operating system will silently drop |
|
|
933 | this interest. If another file descriptor with the same number then is |
|
|
934 | registered with libev, there is no efficient way to see that this is, in |
|
|
935 | fact, a different file descriptor. |
|
|
936 | |
|
|
937 | To avoid having to explicitly tell libev about such cases, libev follows |
|
|
938 | the following policy: Each time C<ev_io_set> is being called, libev |
|
|
939 | will assume that this is potentially a new file descriptor, otherwise |
|
|
940 | it is assumed that the file descriptor stays the same. That means that |
|
|
941 | you I<have> to call C<ev_io_set> (or C<ev_io_init>) when you change the |
|
|
942 | descriptor even if the file descriptor number itself did not change. |
|
|
943 | |
|
|
944 | This is how one would do it normally anyway, the important point is that |
|
|
945 | the libev application should not optimise around libev but should leave |
|
|
946 | optimisations to libev. |
|
|
947 | |
|
|
948 | |
|
|
949 | =head3 Watcher-Specific Functions |
836 | |
950 | |
837 | =over 4 |
951 | =over 4 |
838 | |
952 | |
839 | =item ev_io_init (ev_io *, callback, int fd, int events) |
953 | =item ev_io_init (ev_io *, callback, int fd, int events) |
840 | |
954 | |
… | |
… | |
894 | |
1008 | |
895 | The callback is guarenteed to be invoked only when its timeout has passed, |
1009 | The callback is guarenteed to be invoked only when its timeout has passed, |
896 | but if multiple timers become ready during the same loop iteration then |
1010 | but if multiple timers become ready during the same loop iteration then |
897 | order of execution is undefined. |
1011 | order of execution is undefined. |
898 | |
1012 | |
|
|
1013 | =head3 Watcher-Specific Functions and Data Members |
|
|
1014 | |
899 | =over 4 |
1015 | =over 4 |
900 | |
1016 | |
901 | =item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat) |
1017 | =item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat) |
902 | |
1018 | |
903 | =item ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat) |
1019 | =item ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat) |
… | |
… | |
916 | =item ev_timer_again (loop) |
1032 | =item ev_timer_again (loop) |
917 | |
1033 | |
918 | This will act as if the timer timed out and restart it again if it is |
1034 | This will act as if the timer timed out and restart it again if it is |
919 | repeating. The exact semantics are: |
1035 | repeating. The exact semantics are: |
920 | |
1036 | |
|
|
1037 | If the timer is pending, its pending status is cleared. |
|
|
1038 | |
921 | If the timer is started but nonrepeating, stop it. |
1039 | If the timer is started but nonrepeating, stop it (as if it timed out). |
922 | |
1040 | |
923 | If the timer is repeating, either start it if necessary (with the repeat |
1041 | If the timer is repeating, either start it if necessary (with the |
924 | value), or reset the running timer to the repeat value. |
1042 | C<repeat> value), or reset the running timer to the C<repeat> value. |
925 | |
1043 | |
926 | This sounds a bit complicated, but here is a useful and typical |
1044 | This sounds a bit complicated, but here is a useful and typical |
927 | example: Imagine you have a tcp connection and you want a so-called |
1045 | example: Imagine you have a tcp connection and you want a so-called idle |
928 | idle timeout, that is, you want to be called when there have been, |
1046 | timeout, that is, you want to be called when there have been, say, 60 |
929 | say, 60 seconds of inactivity on the socket. The easiest way to do |
1047 | seconds of inactivity on the socket. The easiest way to do this is to |
930 | this is to configure an C<ev_timer> with C<after>=C<repeat>=C<60> and calling |
1048 | configure an C<ev_timer> with a C<repeat> value of C<60> and then call |
931 | C<ev_timer_again> each time you successfully read or write some data. If |
1049 | C<ev_timer_again> each time you successfully read or write some data. If |
932 | you go into an idle state where you do not expect data to travel on the |
1050 | you go into an idle state where you do not expect data to travel on the |
933 | socket, you can stop the timer, and again will automatically restart it if |
1051 | socket, you can C<ev_timer_stop> the timer, and C<ev_timer_again> will |
934 | need be. |
1052 | automatically restart it if need be. |
935 | |
1053 | |
936 | You can also ignore the C<after> value and C<ev_timer_start> altogether |
1054 | That means you can ignore the C<after> value and C<ev_timer_start> |
937 | and only ever use the C<repeat> value: |
1055 | altogether and only ever use the C<repeat> value and C<ev_timer_again>: |
938 | |
1056 | |
939 | ev_timer_init (timer, callback, 0., 5.); |
1057 | ev_timer_init (timer, callback, 0., 5.); |
940 | ev_timer_again (loop, timer); |
1058 | ev_timer_again (loop, timer); |
941 | ... |
1059 | ... |
942 | timer->again = 17.; |
1060 | timer->again = 17.; |
943 | ev_timer_again (loop, timer); |
1061 | ev_timer_again (loop, timer); |
944 | ... |
1062 | ... |
945 | timer->again = 10.; |
1063 | timer->again = 10.; |
946 | ev_timer_again (loop, timer); |
1064 | ev_timer_again (loop, timer); |
947 | |
1065 | |
948 | This is more efficient then stopping/starting the timer eahc time you want |
1066 | This is more slightly efficient then stopping/starting the timer each time |
949 | to modify its timeout value. |
1067 | you want to modify its timeout value. |
950 | |
1068 | |
951 | =item ev_tstamp repeat [read-write] |
1069 | =item ev_tstamp repeat [read-write] |
952 | |
1070 | |
953 | The current C<repeat> value. Will be used each time the watcher times out |
1071 | The current C<repeat> value. Will be used each time the watcher times out |
954 | or C<ev_timer_again> is called and determines the next timeout (if any), |
1072 | or C<ev_timer_again> is called and determines the next timeout (if any), |
… | |
… | |
996 | but on wallclock time (absolute time). You can tell a periodic watcher |
1114 | but on wallclock time (absolute time). You can tell a periodic watcher |
997 | to trigger "at" some specific point in time. For example, if you tell a |
1115 | to trigger "at" some specific point in time. For example, if you tell a |
998 | periodic watcher to trigger in 10 seconds (by specifiying e.g. C<ev_now () |
1116 | periodic watcher to trigger in 10 seconds (by specifiying e.g. C<ev_now () |
999 | + 10.>) and then reset your system clock to the last year, then it will |
1117 | + 10.>) and then reset your system clock to the last year, then it will |
1000 | take a year to trigger the event (unlike an C<ev_timer>, which would trigger |
1118 | take a year to trigger the event (unlike an C<ev_timer>, which would trigger |
1001 | roughly 10 seconds later and of course not if you reset your system time |
1119 | roughly 10 seconds later). |
1002 | again). |
|
|
1003 | |
1120 | |
1004 | They can also be used to implement vastly more complex timers, such as |
1121 | They can also be used to implement vastly more complex timers, such as |
1005 | triggering an event on eahc midnight, local time. |
1122 | triggering an event on each midnight, local time or other, complicated, |
|
|
1123 | rules. |
1006 | |
1124 | |
1007 | As with timers, the callback is guarenteed to be invoked only when the |
1125 | As with timers, the callback is guarenteed to be invoked only when the |
1008 | time (C<at>) has been passed, but if multiple periodic timers become ready |
1126 | time (C<at>) has been passed, but if multiple periodic timers become ready |
1009 | during the same loop iteration then order of execution is undefined. |
1127 | during the same loop iteration then order of execution is undefined. |
1010 | |
1128 | |
|
|
1129 | =head3 Watcher-Specific Functions and Data Members |
|
|
1130 | |
1011 | =over 4 |
1131 | =over 4 |
1012 | |
1132 | |
1013 | =item ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb) |
1133 | =item ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb) |
1014 | |
1134 | |
1015 | =item ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb) |
1135 | =item ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb) |
… | |
… | |
1017 | Lots of arguments, lets sort it out... There are basically three modes of |
1137 | Lots of arguments, lets sort it out... There are basically three modes of |
1018 | operation, and we will explain them from simplest to complex: |
1138 | operation, and we will explain them from simplest to complex: |
1019 | |
1139 | |
1020 | =over 4 |
1140 | =over 4 |
1021 | |
1141 | |
1022 | =item * absolute timer (interval = reschedule_cb = 0) |
1142 | =item * absolute timer (at = time, interval = reschedule_cb = 0) |
1023 | |
1143 | |
1024 | In this configuration the watcher triggers an event at the wallclock time |
1144 | In this configuration the watcher triggers an event at the wallclock time |
1025 | C<at> and doesn't repeat. It will not adjust when a time jump occurs, |
1145 | C<at> and doesn't repeat. It will not adjust when a time jump occurs, |
1026 | that is, if it is to be run at January 1st 2011 then it will run when the |
1146 | that is, if it is to be run at January 1st 2011 then it will run when the |
1027 | system time reaches or surpasses this time. |
1147 | system time reaches or surpasses this time. |
1028 | |
1148 | |
1029 | =item * non-repeating interval timer (interval > 0, reschedule_cb = 0) |
1149 | =item * non-repeating interval timer (at = offset, interval > 0, reschedule_cb = 0) |
1030 | |
1150 | |
1031 | In this mode the watcher will always be scheduled to time out at the next |
1151 | In this mode the watcher will always be scheduled to time out at the next |
1032 | C<at + N * interval> time (for some integer N) and then repeat, regardless |
1152 | C<at + N * interval> time (for some integer N, which can also be negative) |
1033 | of any time jumps. |
1153 | and then repeat, regardless of any time jumps. |
1034 | |
1154 | |
1035 | This can be used to create timers that do not drift with respect to system |
1155 | This can be used to create timers that do not drift with respect to system |
1036 | time: |
1156 | time: |
1037 | |
1157 | |
1038 | ev_periodic_set (&periodic, 0., 3600., 0); |
1158 | ev_periodic_set (&periodic, 0., 3600., 0); |
… | |
… | |
1044 | |
1164 | |
1045 | Another way to think about it (for the mathematically inclined) is that |
1165 | Another way to think about it (for the mathematically inclined) is that |
1046 | C<ev_periodic> will try to run the callback in this mode at the next possible |
1166 | C<ev_periodic> will try to run the callback in this mode at the next possible |
1047 | time where C<time = at (mod interval)>, regardless of any time jumps. |
1167 | time where C<time = at (mod interval)>, regardless of any time jumps. |
1048 | |
1168 | |
|
|
1169 | For numerical stability it is preferable that the C<at> value is near |
|
|
1170 | C<ev_now ()> (the current time), but there is no range requirement for |
|
|
1171 | this value. |
|
|
1172 | |
1049 | =item * manual reschedule mode (reschedule_cb = callback) |
1173 | =item * manual reschedule mode (at and interval ignored, reschedule_cb = callback) |
1050 | |
1174 | |
1051 | In this mode the values for C<interval> and C<at> are both being |
1175 | In this mode the values for C<interval> and C<at> are both being |
1052 | ignored. Instead, each time the periodic watcher gets scheduled, the |
1176 | ignored. Instead, each time the periodic watcher gets scheduled, the |
1053 | reschedule callback will be called with the watcher as first, and the |
1177 | reschedule callback will be called with the watcher as first, and the |
1054 | current time as second argument. |
1178 | current time as second argument. |
1055 | |
1179 | |
1056 | NOTE: I<This callback MUST NOT stop or destroy any periodic watcher, |
1180 | NOTE: I<This callback MUST NOT stop or destroy any periodic watcher, |
1057 | ever, or make any event loop modifications>. If you need to stop it, |
1181 | ever, or make any event loop modifications>. If you need to stop it, |
1058 | return C<now + 1e30> (or so, fudge fudge) and stop it afterwards (e.g. by |
1182 | return C<now + 1e30> (or so, fudge fudge) and stop it afterwards (e.g. by |
1059 | starting a prepare watcher). |
1183 | starting an C<ev_prepare> watcher, which is legal). |
1060 | |
1184 | |
1061 | Its prototype is C<ev_tstamp (*reschedule_cb)(struct ev_periodic *w, |
1185 | Its prototype is C<ev_tstamp (*reschedule_cb)(struct ev_periodic *w, |
1062 | ev_tstamp now)>, e.g.: |
1186 | ev_tstamp now)>, e.g.: |
1063 | |
1187 | |
1064 | static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now) |
1188 | static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now) |
… | |
… | |
1087 | Simply stops and restarts the periodic watcher again. This is only useful |
1211 | Simply stops and restarts the periodic watcher again. This is only useful |
1088 | when you changed some parameters or the reschedule callback would return |
1212 | when you changed some parameters or the reschedule callback would return |
1089 | a different time than the last time it was called (e.g. in a crond like |
1213 | a different time than the last time it was called (e.g. in a crond like |
1090 | program when the crontabs have changed). |
1214 | program when the crontabs have changed). |
1091 | |
1215 | |
|
|
1216 | =item ev_tstamp offset [read-write] |
|
|
1217 | |
|
|
1218 | When repeating, this contains the offset value, otherwise this is the |
|
|
1219 | absolute point in time (the C<at> value passed to C<ev_periodic_set>). |
|
|
1220 | |
|
|
1221 | Can be modified any time, but changes only take effect when the periodic |
|
|
1222 | timer fires or C<ev_periodic_again> is being called. |
|
|
1223 | |
1092 | =item ev_tstamp interval [read-write] |
1224 | =item ev_tstamp interval [read-write] |
1093 | |
1225 | |
1094 | The current interval value. Can be modified any time, but changes only |
1226 | The current interval value. Can be modified any time, but changes only |
1095 | take effect when the periodic timer fires or C<ev_periodic_again> is being |
1227 | take effect when the periodic timer fires or C<ev_periodic_again> is being |
1096 | called. |
1228 | called. |
… | |
… | |
1098 | =item ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read-write] |
1230 | =item ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read-write] |
1099 | |
1231 | |
1100 | The current reschedule callback, or C<0>, if this functionality is |
1232 | The current reschedule callback, or C<0>, if this functionality is |
1101 | switched off. Can be changed any time, but changes only take effect when |
1233 | switched off. Can be changed any time, but changes only take effect when |
1102 | the periodic timer fires or C<ev_periodic_again> is being called. |
1234 | the periodic timer fires or C<ev_periodic_again> is being called. |
|
|
1235 | |
|
|
1236 | =item ev_tstamp at [read-only] |
|
|
1237 | |
|
|
1238 | When active, contains the absolute time that the watcher is supposed to |
|
|
1239 | trigger next. |
1103 | |
1240 | |
1104 | =back |
1241 | =back |
1105 | |
1242 | |
1106 | Example: Call a callback every hour, or, more precisely, whenever the |
1243 | Example: Call a callback every hour, or, more precisely, whenever the |
1107 | system clock is divisible by 3600. The callback invocation times have |
1244 | system clock is divisible by 3600. The callback invocation times have |
… | |
… | |
1149 | with the kernel (thus it coexists with your own signal handlers as long |
1286 | with the kernel (thus it coexists with your own signal handlers as long |
1150 | as you don't register any with libev). Similarly, when the last signal |
1287 | as you don't register any with libev). Similarly, when the last signal |
1151 | watcher for a signal is stopped libev will reset the signal handler to |
1288 | watcher for a signal is stopped libev will reset the signal handler to |
1152 | SIG_DFL (regardless of what it was set to before). |
1289 | SIG_DFL (regardless of what it was set to before). |
1153 | |
1290 | |
|
|
1291 | =head3 Watcher-Specific Functions and Data Members |
|
|
1292 | |
1154 | =over 4 |
1293 | =over 4 |
1155 | |
1294 | |
1156 | =item ev_signal_init (ev_signal *, callback, int signum) |
1295 | =item ev_signal_init (ev_signal *, callback, int signum) |
1157 | |
1296 | |
1158 | =item ev_signal_set (ev_signal *, int signum) |
1297 | =item ev_signal_set (ev_signal *, int signum) |
… | |
… | |
1169 | |
1308 | |
1170 | =head2 C<ev_child> - watch out for process status changes |
1309 | =head2 C<ev_child> - watch out for process status changes |
1171 | |
1310 | |
1172 | Child watchers trigger when your process receives a SIGCHLD in response to |
1311 | Child watchers trigger when your process receives a SIGCHLD in response to |
1173 | some child status changes (most typically when a child of yours dies). |
1312 | some child status changes (most typically when a child of yours dies). |
|
|
1313 | |
|
|
1314 | =head3 Watcher-Specific Functions and Data Members |
1174 | |
1315 | |
1175 | =over 4 |
1316 | =over 4 |
1176 | |
1317 | |
1177 | =item ev_child_init (ev_child *, callback, int pid) |
1318 | =item ev_child_init (ev_child *, callback, int pid) |
1178 | |
1319 | |
… | |
… | |
1246 | reader). Inotify will be used to give hints only and should not change the |
1387 | reader). Inotify will be used to give hints only and should not change the |
1247 | semantics of C<ev_stat> watchers, which means that libev sometimes needs |
1388 | semantics of C<ev_stat> watchers, which means that libev sometimes needs |
1248 | to fall back to regular polling again even with inotify, but changes are |
1389 | to fall back to regular polling again even with inotify, but changes are |
1249 | usually detected immediately, and if the file exists there will be no |
1390 | usually detected immediately, and if the file exists there will be no |
1250 | polling. |
1391 | polling. |
|
|
1392 | |
|
|
1393 | =head3 Watcher-Specific Functions and Data Members |
1251 | |
1394 | |
1252 | =over 4 |
1395 | =over 4 |
1253 | |
1396 | |
1254 | =item ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval) |
1397 | =item ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval) |
1255 | |
1398 | |
… | |
… | |
1319 | ev_stat_start (loop, &passwd); |
1462 | ev_stat_start (loop, &passwd); |
1320 | |
1463 | |
1321 | |
1464 | |
1322 | =head2 C<ev_idle> - when you've got nothing better to do... |
1465 | =head2 C<ev_idle> - when you've got nothing better to do... |
1323 | |
1466 | |
1324 | Idle watchers trigger events when there are no other events are pending |
1467 | Idle watchers trigger events when no other events of the same or higher |
1325 | (prepare, check and other idle watchers do not count). That is, as long |
1468 | priority are pending (prepare, check and other idle watchers do not |
1326 | as your process is busy handling sockets or timeouts (or even signals, |
1469 | count). |
1327 | imagine) it will not be triggered. But when your process is idle all idle |
1470 | |
1328 | watchers are being called again and again, once per event loop iteration - |
1471 | That is, as long as your process is busy handling sockets or timeouts |
|
|
1472 | (or even signals, imagine) of the same or higher priority it will not be |
|
|
1473 | triggered. But when your process is idle (or only lower-priority watchers |
|
|
1474 | are pending), the idle watchers are being called once per event loop |
1329 | until stopped, that is, or your process receives more events and becomes |
1475 | iteration - until stopped, that is, or your process receives more events |
1330 | busy. |
1476 | and becomes busy again with higher priority stuff. |
1331 | |
1477 | |
1332 | The most noteworthy effect is that as long as any idle watchers are |
1478 | The most noteworthy effect is that as long as any idle watchers are |
1333 | active, the process will not block when waiting for new events. |
1479 | active, the process will not block when waiting for new events. |
1334 | |
1480 | |
1335 | Apart from keeping your process non-blocking (which is a useful |
1481 | Apart from keeping your process non-blocking (which is a useful |
1336 | effect on its own sometimes), idle watchers are a good place to do |
1482 | effect on its own sometimes), idle watchers are a good place to do |
1337 | "pseudo-background processing", or delay processing stuff to after the |
1483 | "pseudo-background processing", or delay processing stuff to after the |
1338 | event loop has handled all outstanding events. |
1484 | event loop has handled all outstanding events. |
|
|
1485 | |
|
|
1486 | =head3 Watcher-Specific Functions and Data Members |
1339 | |
1487 | |
1340 | =over 4 |
1488 | =over 4 |
1341 | |
1489 | |
1342 | =item ev_idle_init (ev_signal *, callback) |
1490 | =item ev_idle_init (ev_signal *, callback) |
1343 | |
1491 | |
… | |
… | |
1401 | with priority higher than or equal to the event loop and one coroutine |
1549 | with priority higher than or equal to the event loop and one coroutine |
1402 | of lower priority, but only once, using idle watchers to keep the event |
1550 | of lower priority, but only once, using idle watchers to keep the event |
1403 | loop from blocking if lower-priority coroutines are active, thus mapping |
1551 | loop from blocking if lower-priority coroutines are active, thus mapping |
1404 | low-priority coroutines to idle/background tasks). |
1552 | low-priority coroutines to idle/background tasks). |
1405 | |
1553 | |
|
|
1554 | It is recommended to give C<ev_check> watchers highest (C<EV_MAXPRI>) |
|
|
1555 | priority, to ensure that they are being run before any other watchers |
|
|
1556 | after the poll. Also, C<ev_check> watchers (and C<ev_prepare> watchers, |
|
|
1557 | too) should not activate ("feed") events into libev. While libev fully |
|
|
1558 | supports this, they will be called before other C<ev_check> watchers did |
|
|
1559 | their job. As C<ev_check> watchers are often used to embed other event |
|
|
1560 | loops those other event loops might be in an unusable state until their |
|
|
1561 | C<ev_check> watcher ran (always remind yourself to coexist peacefully with |
|
|
1562 | others). |
|
|
1563 | |
|
|
1564 | =head3 Watcher-Specific Functions and Data Members |
|
|
1565 | |
1406 | =over 4 |
1566 | =over 4 |
1407 | |
1567 | |
1408 | =item ev_prepare_init (ev_prepare *, callback) |
1568 | =item ev_prepare_init (ev_prepare *, callback) |
1409 | |
1569 | |
1410 | =item ev_check_init (ev_check *, callback) |
1570 | =item ev_check_init (ev_check *, callback) |
… | |
… | |
1413 | parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set> |
1573 | parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set> |
1414 | macros, but using them is utterly, utterly and completely pointless. |
1574 | macros, but using them is utterly, utterly and completely pointless. |
1415 | |
1575 | |
1416 | =back |
1576 | =back |
1417 | |
1577 | |
1418 | Example: To include a library such as adns, you would add IO watchers |
1578 | There are a number of principal ways to embed other event loops or modules |
1419 | and a timeout watcher in a prepare handler, as required by libadns, and |
1579 | into libev. Here are some ideas on how to include libadns into libev |
|
|
1580 | (there is a Perl module named C<EV::ADNS> that does this, which you could |
|
|
1581 | use for an actually working example. Another Perl module named C<EV::Glib> |
|
|
1582 | embeds a Glib main context into libev, and finally, C<Glib::EV> embeds EV |
|
|
1583 | into the Glib event loop). |
|
|
1584 | |
|
|
1585 | Method 1: Add IO watchers and a timeout watcher in a prepare handler, |
1420 | in a check watcher, destroy them and call into libadns. What follows is |
1586 | and in a check watcher, destroy them and call into libadns. What follows |
1421 | pseudo-code only of course: |
1587 | is pseudo-code only of course. This requires you to either use a low |
|
|
1588 | priority for the check watcher or use C<ev_clear_pending> explicitly, as |
|
|
1589 | the callbacks for the IO/timeout watchers might not have been called yet. |
1422 | |
1590 | |
1423 | static ev_io iow [nfd]; |
1591 | static ev_io iow [nfd]; |
1424 | static ev_timer tw; |
1592 | static ev_timer tw; |
1425 | |
1593 | |
1426 | static void |
1594 | static void |
1427 | io_cb (ev_loop *loop, ev_io *w, int revents) |
1595 | io_cb (ev_loop *loop, ev_io *w, int revents) |
1428 | { |
1596 | { |
1429 | // set the relevant poll flags |
|
|
1430 | // could also call adns_processreadable etc. here |
|
|
1431 | struct pollfd *fd = (struct pollfd *)w->data; |
|
|
1432 | if (revents & EV_READ ) fd->revents |= fd->events & POLLIN; |
|
|
1433 | if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT; |
|
|
1434 | } |
1597 | } |
1435 | |
1598 | |
1436 | // create io watchers for each fd and a timer before blocking |
1599 | // create io watchers for each fd and a timer before blocking |
1437 | static void |
1600 | static void |
1438 | adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) |
1601 | adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) |
1439 | { |
1602 | { |
1440 | int timeout = 3600000;truct pollfd fds [nfd]; |
1603 | int timeout = 3600000; |
|
|
1604 | struct pollfd fds [nfd]; |
1441 | // actual code will need to loop here and realloc etc. |
1605 | // actual code will need to loop here and realloc etc. |
1442 | adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
1606 | adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
1443 | |
1607 | |
1444 | /* the callback is illegal, but won't be called as we stop during check */ |
1608 | /* the callback is illegal, but won't be called as we stop during check */ |
1445 | ev_timer_init (&tw, 0, timeout * 1e-3); |
1609 | ev_timer_init (&tw, 0, timeout * 1e-3); |
1446 | ev_timer_start (loop, &tw); |
1610 | ev_timer_start (loop, &tw); |
1447 | |
1611 | |
1448 | // create on ev_io per pollfd |
1612 | // create one ev_io per pollfd |
1449 | for (int i = 0; i < nfd; ++i) |
1613 | for (int i = 0; i < nfd; ++i) |
1450 | { |
1614 | { |
1451 | ev_io_init (iow + i, io_cb, fds [i].fd, |
1615 | ev_io_init (iow + i, io_cb, fds [i].fd, |
1452 | ((fds [i].events & POLLIN ? EV_READ : 0) |
1616 | ((fds [i].events & POLLIN ? EV_READ : 0) |
1453 | | (fds [i].events & POLLOUT ? EV_WRITE : 0))); |
1617 | | (fds [i].events & POLLOUT ? EV_WRITE : 0))); |
1454 | |
1618 | |
1455 | fds [i].revents = 0; |
1619 | fds [i].revents = 0; |
1456 | iow [i].data = fds + i; |
|
|
1457 | ev_io_start (loop, iow + i); |
1620 | ev_io_start (loop, iow + i); |
1458 | } |
1621 | } |
1459 | } |
1622 | } |
1460 | |
1623 | |
1461 | // stop all watchers after blocking |
1624 | // stop all watchers after blocking |
… | |
… | |
1463 | adns_check_cb (ev_loop *loop, ev_check *w, int revents) |
1626 | adns_check_cb (ev_loop *loop, ev_check *w, int revents) |
1464 | { |
1627 | { |
1465 | ev_timer_stop (loop, &tw); |
1628 | ev_timer_stop (loop, &tw); |
1466 | |
1629 | |
1467 | for (int i = 0; i < nfd; ++i) |
1630 | for (int i = 0; i < nfd; ++i) |
|
|
1631 | { |
|
|
1632 | // set the relevant poll flags |
|
|
1633 | // could also call adns_processreadable etc. here |
|
|
1634 | struct pollfd *fd = fds + i; |
|
|
1635 | int revents = ev_clear_pending (iow + i); |
|
|
1636 | if (revents & EV_READ ) fd->revents |= fd->events & POLLIN; |
|
|
1637 | if (revents & EV_WRITE) fd->revents |= fd->events & POLLOUT; |
|
|
1638 | |
|
|
1639 | // now stop the watcher |
1468 | ev_io_stop (loop, iow + i); |
1640 | ev_io_stop (loop, iow + i); |
|
|
1641 | } |
1469 | |
1642 | |
1470 | adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop)); |
1643 | adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop)); |
|
|
1644 | } |
|
|
1645 | |
|
|
1646 | Method 2: This would be just like method 1, but you run C<adns_afterpoll> |
|
|
1647 | in the prepare watcher and would dispose of the check watcher. |
|
|
1648 | |
|
|
1649 | Method 3: If the module to be embedded supports explicit event |
|
|
1650 | notification (adns does), you can also make use of the actual watcher |
|
|
1651 | callbacks, and only destroy/create the watchers in the prepare watcher. |
|
|
1652 | |
|
|
1653 | static void |
|
|
1654 | timer_cb (EV_P_ ev_timer *w, int revents) |
|
|
1655 | { |
|
|
1656 | adns_state ads = (adns_state)w->data; |
|
|
1657 | update_now (EV_A); |
|
|
1658 | |
|
|
1659 | adns_processtimeouts (ads, &tv_now); |
|
|
1660 | } |
|
|
1661 | |
|
|
1662 | static void |
|
|
1663 | io_cb (EV_P_ ev_io *w, int revents) |
|
|
1664 | { |
|
|
1665 | adns_state ads = (adns_state)w->data; |
|
|
1666 | update_now (EV_A); |
|
|
1667 | |
|
|
1668 | if (revents & EV_READ ) adns_processreadable (ads, w->fd, &tv_now); |
|
|
1669 | if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now); |
|
|
1670 | } |
|
|
1671 | |
|
|
1672 | // do not ever call adns_afterpoll |
|
|
1673 | |
|
|
1674 | Method 4: Do not use a prepare or check watcher because the module you |
|
|
1675 | want to embed is too inflexible to support it. Instead, youc na override |
|
|
1676 | their poll function. The drawback with this solution is that the main |
|
|
1677 | loop is now no longer controllable by EV. The C<Glib::EV> module does |
|
|
1678 | this. |
|
|
1679 | |
|
|
1680 | static gint |
|
|
1681 | event_poll_func (GPollFD *fds, guint nfds, gint timeout) |
|
|
1682 | { |
|
|
1683 | int got_events = 0; |
|
|
1684 | |
|
|
1685 | for (n = 0; n < nfds; ++n) |
|
|
1686 | // create/start io watcher that sets the relevant bits in fds[n] and increment got_events |
|
|
1687 | |
|
|
1688 | if (timeout >= 0) |
|
|
1689 | // create/start timer |
|
|
1690 | |
|
|
1691 | // poll |
|
|
1692 | ev_loop (EV_A_ 0); |
|
|
1693 | |
|
|
1694 | // stop timer again |
|
|
1695 | if (timeout >= 0) |
|
|
1696 | ev_timer_stop (EV_A_ &to); |
|
|
1697 | |
|
|
1698 | // stop io watchers again - their callbacks should have set |
|
|
1699 | for (n = 0; n < nfds; ++n) |
|
|
1700 | ev_io_stop (EV_A_ iow [n]); |
|
|
1701 | |
|
|
1702 | return got_events; |
1471 | } |
1703 | } |
1472 | |
1704 | |
1473 | |
1705 | |
1474 | =head2 C<ev_embed> - when one backend isn't enough... |
1706 | =head2 C<ev_embed> - when one backend isn't enough... |
1475 | |
1707 | |
… | |
… | |
1539 | ev_embed_start (loop_hi, &embed); |
1771 | ev_embed_start (loop_hi, &embed); |
1540 | } |
1772 | } |
1541 | else |
1773 | else |
1542 | loop_lo = loop_hi; |
1774 | loop_lo = loop_hi; |
1543 | |
1775 | |
|
|
1776 | =head3 Watcher-Specific Functions and Data Members |
|
|
1777 | |
1544 | =over 4 |
1778 | =over 4 |
1545 | |
1779 | |
1546 | =item ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop) |
1780 | =item ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop) |
1547 | |
1781 | |
1548 | =item ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop) |
1782 | =item ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop) |
… | |
… | |
1574 | event loop blocks next and before C<ev_check> watchers are being called, |
1808 | event loop blocks next and before C<ev_check> watchers are being called, |
1575 | and only in the child after the fork. If whoever good citizen calling |
1809 | and only in the child after the fork. If whoever good citizen calling |
1576 | C<ev_default_fork> cheats and calls it in the wrong process, the fork |
1810 | C<ev_default_fork> cheats and calls it in the wrong process, the fork |
1577 | handlers will be invoked, too, of course. |
1811 | handlers will be invoked, too, of course. |
1578 | |
1812 | |
|
|
1813 | =head3 Watcher-Specific Functions and Data Members |
|
|
1814 | |
1579 | =over 4 |
1815 | =over 4 |
1580 | |
1816 | |
1581 | =item ev_fork_init (ev_signal *, callback) |
1817 | =item ev_fork_init (ev_signal *, callback) |
1582 | |
1818 | |
1583 | Initialises and configures the fork watcher - it has no parameters of any |
1819 | Initialises and configures the fork watcher - it has no parameters of any |
… | |
… | |
1679 | |
1915 | |
1680 | To use it, |
1916 | To use it, |
1681 | |
1917 | |
1682 | #include <ev++.h> |
1918 | #include <ev++.h> |
1683 | |
1919 | |
1684 | (it is not installed by default). This automatically includes F<ev.h> |
1920 | This automatically includes F<ev.h> and puts all of its definitions (many |
1685 | and puts all of its definitions (many of them macros) into the global |
1921 | of them macros) into the global namespace. All C++ specific things are |
1686 | namespace. All C++ specific things are put into the C<ev> namespace. |
1922 | put into the C<ev> namespace. It should support all the same embedding |
|
|
1923 | options as F<ev.h>, most notably C<EV_MULTIPLICITY>. |
1687 | |
1924 | |
1688 | It should support all the same embedding options as F<ev.h>, most notably |
1925 | Care has been taken to keep the overhead low. The only data member the C++ |
1689 | C<EV_MULTIPLICITY>. |
1926 | classes add (compared to plain C-style watchers) is the event loop pointer |
|
|
1927 | that the watcher is associated with (or no additional members at all if |
|
|
1928 | you disable C<EV_MULTIPLICITY> when embedding libev). |
|
|
1929 | |
|
|
1930 | Currently, functions, and static and non-static member functions can be |
|
|
1931 | used as callbacks. Other types should be easy to add as long as they only |
|
|
1932 | need one additional pointer for context. If you need support for other |
|
|
1933 | types of functors please contact the author (preferably after implementing |
|
|
1934 | it). |
1690 | |
1935 | |
1691 | Here is a list of things available in the C<ev> namespace: |
1936 | Here is a list of things available in the C<ev> namespace: |
1692 | |
1937 | |
1693 | =over 4 |
1938 | =over 4 |
1694 | |
1939 | |
… | |
… | |
1710 | |
1955 | |
1711 | All of those classes have these methods: |
1956 | All of those classes have these methods: |
1712 | |
1957 | |
1713 | =over 4 |
1958 | =over 4 |
1714 | |
1959 | |
1715 | =item ev::TYPE::TYPE (object *, object::method *) |
1960 | =item ev::TYPE::TYPE () |
1716 | |
1961 | |
1717 | =item ev::TYPE::TYPE (object *, object::method *, struct ev_loop *) |
1962 | =item ev::TYPE::TYPE (struct ev_loop *) |
1718 | |
1963 | |
1719 | =item ev::TYPE::~TYPE |
1964 | =item ev::TYPE::~TYPE |
1720 | |
1965 | |
1721 | The constructor takes a pointer to an object and a method pointer to |
1966 | The constructor (optionally) takes an event loop to associate the watcher |
1722 | the event handler callback to call in this class. The constructor calls |
1967 | with. If it is omitted, it will use C<EV_DEFAULT>. |
1723 | C<ev_init> for you, which means you have to call the C<set> method |
1968 | |
1724 | before starting it. If you do not specify a loop then the constructor |
1969 | The constructor calls C<ev_init> for you, which means you have to call the |
1725 | automatically associates the default loop with this watcher. |
1970 | C<set> method before starting it. |
|
|
1971 | |
|
|
1972 | It will not set a callback, however: You have to call the templated C<set> |
|
|
1973 | method to set a callback before you can start the watcher. |
|
|
1974 | |
|
|
1975 | (The reason why you have to use a method is a limitation in C++ which does |
|
|
1976 | not allow explicit template arguments for constructors). |
1726 | |
1977 | |
1727 | The destructor automatically stops the watcher if it is active. |
1978 | The destructor automatically stops the watcher if it is active. |
|
|
1979 | |
|
|
1980 | =item w->set<class, &class::method> (object *) |
|
|
1981 | |
|
|
1982 | This method sets the callback method to call. The method has to have a |
|
|
1983 | signature of C<void (*)(ev_TYPE &, int)>, it receives the watcher as |
|
|
1984 | first argument and the C<revents> as second. The object must be given as |
|
|
1985 | parameter and is stored in the C<data> member of the watcher. |
|
|
1986 | |
|
|
1987 | This method synthesizes efficient thunking code to call your method from |
|
|
1988 | the C callback that libev requires. If your compiler can inline your |
|
|
1989 | callback (i.e. it is visible to it at the place of the C<set> call and |
|
|
1990 | your compiler is good :), then the method will be fully inlined into the |
|
|
1991 | thunking function, making it as fast as a direct C callback. |
|
|
1992 | |
|
|
1993 | Example: simple class declaration and watcher initialisation |
|
|
1994 | |
|
|
1995 | struct myclass |
|
|
1996 | { |
|
|
1997 | void io_cb (ev::io &w, int revents) { } |
|
|
1998 | } |
|
|
1999 | |
|
|
2000 | myclass obj; |
|
|
2001 | ev::io iow; |
|
|
2002 | iow.set <myclass, &myclass::io_cb> (&obj); |
|
|
2003 | |
|
|
2004 | =item w->set<function> (void *data = 0) |
|
|
2005 | |
|
|
2006 | Also sets a callback, but uses a static method or plain function as |
|
|
2007 | callback. The optional C<data> argument will be stored in the watcher's |
|
|
2008 | C<data> member and is free for you to use. |
|
|
2009 | |
|
|
2010 | The prototype of the C<function> must be C<void (*)(ev::TYPE &w, int)>. |
|
|
2011 | |
|
|
2012 | See the method-C<set> above for more details. |
|
|
2013 | |
|
|
2014 | Example: |
|
|
2015 | |
|
|
2016 | static void io_cb (ev::io &w, int revents) { } |
|
|
2017 | iow.set <io_cb> (); |
1728 | |
2018 | |
1729 | =item w->set (struct ev_loop *) |
2019 | =item w->set (struct ev_loop *) |
1730 | |
2020 | |
1731 | Associates a different C<struct ev_loop> with this watcher. You can only |
2021 | Associates a different C<struct ev_loop> with this watcher. You can only |
1732 | do this when the watcher is inactive (and not pending either). |
2022 | do this when the watcher is inactive (and not pending either). |
1733 | |
2023 | |
1734 | =item w->set ([args]) |
2024 | =item w->set ([args]) |
1735 | |
2025 | |
1736 | Basically the same as C<ev_TYPE_set>, with the same args. Must be |
2026 | Basically the same as C<ev_TYPE_set>, with the same args. Must be |
1737 | called at least once. Unlike the C counterpart, an active watcher gets |
2027 | called at least once. Unlike the C counterpart, an active watcher gets |
1738 | automatically stopped and restarted. |
2028 | automatically stopped and restarted when reconfiguring it with this |
|
|
2029 | method. |
1739 | |
2030 | |
1740 | =item w->start () |
2031 | =item w->start () |
1741 | |
2032 | |
1742 | Starts the watcher. Note that there is no C<loop> argument as the |
2033 | Starts the watcher. Note that there is no C<loop> argument, as the |
1743 | constructor already takes the loop. |
2034 | constructor already stores the event loop. |
1744 | |
2035 | |
1745 | =item w->stop () |
2036 | =item w->stop () |
1746 | |
2037 | |
1747 | Stops the watcher if it is active. Again, no C<loop> argument. |
2038 | Stops the watcher if it is active. Again, no C<loop> argument. |
1748 | |
2039 | |
1749 | =item w->again () C<ev::timer>, C<ev::periodic> only |
2040 | =item w->again () (C<ev::timer>, C<ev::periodic> only) |
1750 | |
2041 | |
1751 | For C<ev::timer> and C<ev::periodic>, this invokes the corresponding |
2042 | For C<ev::timer> and C<ev::periodic>, this invokes the corresponding |
1752 | C<ev_TYPE_again> function. |
2043 | C<ev_TYPE_again> function. |
1753 | |
2044 | |
1754 | =item w->sweep () C<ev::embed> only |
2045 | =item w->sweep () (C<ev::embed> only) |
1755 | |
2046 | |
1756 | Invokes C<ev_embed_sweep>. |
2047 | Invokes C<ev_embed_sweep>. |
1757 | |
2048 | |
1758 | =item w->update () C<ev::stat> only |
2049 | =item w->update () (C<ev::stat> only) |
1759 | |
2050 | |
1760 | Invokes C<ev_stat_stat>. |
2051 | Invokes C<ev_stat_stat>. |
1761 | |
2052 | |
1762 | =back |
2053 | =back |
1763 | |
2054 | |
… | |
… | |
1773 | |
2064 | |
1774 | myclass (); |
2065 | myclass (); |
1775 | } |
2066 | } |
1776 | |
2067 | |
1777 | myclass::myclass (int fd) |
2068 | myclass::myclass (int fd) |
1778 | : io (this, &myclass::io_cb), |
|
|
1779 | idle (this, &myclass::idle_cb) |
|
|
1780 | { |
2069 | { |
|
|
2070 | io .set <myclass, &myclass::io_cb > (this); |
|
|
2071 | idle.set <myclass, &myclass::idle_cb> (this); |
|
|
2072 | |
1781 | io.start (fd, ev::READ); |
2073 | io.start (fd, ev::READ); |
1782 | } |
2074 | } |
1783 | |
2075 | |
1784 | |
2076 | |
1785 | =head1 MACRO MAGIC |
2077 | =head1 MACRO MAGIC |
1786 | |
2078 | |
1787 | Libev can be compiled with a variety of options, the most fundemantal is |
2079 | Libev can be compiled with a variety of options, the most fundamantal |
1788 | C<EV_MULTIPLICITY>. This option determines wether (most) functions and |
2080 | of which is C<EV_MULTIPLICITY>. This option determines whether (most) |
1789 | callbacks have an initial C<struct ev_loop *> argument. |
2081 | functions and callbacks have an initial C<struct ev_loop *> argument. |
1790 | |
2082 | |
1791 | To make it easier to write programs that cope with either variant, the |
2083 | To make it easier to write programs that cope with either variant, the |
1792 | following macros are defined: |
2084 | following macros are defined: |
1793 | |
2085 | |
1794 | =over 4 |
2086 | =over 4 |
… | |
… | |
1826 | Similar to the other two macros, this gives you the value of the default |
2118 | Similar to the other two macros, this gives you the value of the default |
1827 | loop, if multiple loops are supported ("ev loop default"). |
2119 | loop, if multiple loops are supported ("ev loop default"). |
1828 | |
2120 | |
1829 | =back |
2121 | =back |
1830 | |
2122 | |
1831 | Example: Declare and initialise a check watcher, working regardless of |
2123 | Example: Declare and initialise a check watcher, utilising the above |
1832 | wether multiple loops are supported or not. |
2124 | macros so it will work regardless of whether multiple loops are supported |
|
|
2125 | or not. |
1833 | |
2126 | |
1834 | static void |
2127 | static void |
1835 | check_cb (EV_P_ ev_timer *w, int revents) |
2128 | check_cb (EV_P_ ev_timer *w, int revents) |
1836 | { |
2129 | { |
1837 | ev_check_stop (EV_A_ w); |
2130 | ev_check_stop (EV_A_ w); |
… | |
… | |
1839 | |
2132 | |
1840 | ev_check check; |
2133 | ev_check check; |
1841 | ev_check_init (&check, check_cb); |
2134 | ev_check_init (&check, check_cb); |
1842 | ev_check_start (EV_DEFAULT_ &check); |
2135 | ev_check_start (EV_DEFAULT_ &check); |
1843 | ev_loop (EV_DEFAULT_ 0); |
2136 | ev_loop (EV_DEFAULT_ 0); |
1844 | |
|
|
1845 | |
2137 | |
1846 | =head1 EMBEDDING |
2138 | =head1 EMBEDDING |
1847 | |
2139 | |
1848 | Libev can (and often is) directly embedded into host |
2140 | Libev can (and often is) directly embedded into host |
1849 | applications. Examples of applications that embed it include the Deliantra |
2141 | applications. Examples of applications that embed it include the Deliantra |
… | |
… | |
1889 | ev_vars.h |
2181 | ev_vars.h |
1890 | ev_wrap.h |
2182 | ev_wrap.h |
1891 | |
2183 | |
1892 | ev_win32.c required on win32 platforms only |
2184 | ev_win32.c required on win32 platforms only |
1893 | |
2185 | |
1894 | ev_select.c only when select backend is enabled (which is by default) |
2186 | ev_select.c only when select backend is enabled (which is enabled by default) |
1895 | ev_poll.c only when poll backend is enabled (disabled by default) |
2187 | ev_poll.c only when poll backend is enabled (disabled by default) |
1896 | ev_epoll.c only when the epoll backend is enabled (disabled by default) |
2188 | ev_epoll.c only when the epoll backend is enabled (disabled by default) |
1897 | ev_kqueue.c only when the kqueue backend is enabled (disabled by default) |
2189 | ev_kqueue.c only when the kqueue backend is enabled (disabled by default) |
1898 | ev_port.c only when the solaris port backend is enabled (disabled by default) |
2190 | ev_port.c only when the solaris port backend is enabled (disabled by default) |
1899 | |
2191 | |
… | |
… | |
2062 | will have the C<struct ev_loop *> as first argument, and you can create |
2354 | will have the C<struct ev_loop *> as first argument, and you can create |
2063 | additional independent event loops. Otherwise there will be no support |
2355 | additional independent event loops. Otherwise there will be no support |
2064 | for multiple event loops and there is no first event loop pointer |
2356 | for multiple event loops and there is no first event loop pointer |
2065 | argument. Instead, all functions act on the single default loop. |
2357 | argument. Instead, all functions act on the single default loop. |
2066 | |
2358 | |
|
|
2359 | =item EV_MINPRI |
|
|
2360 | |
|
|
2361 | =item EV_MAXPRI |
|
|
2362 | |
|
|
2363 | The range of allowed priorities. C<EV_MINPRI> must be smaller or equal to |
|
|
2364 | C<EV_MAXPRI>, but otherwise there are no non-obvious limitations. You can |
|
|
2365 | provide for more priorities by overriding those symbols (usually defined |
|
|
2366 | to be C<-2> and C<2>, respectively). |
|
|
2367 | |
|
|
2368 | When doing priority-based operations, libev usually has to linearly search |
|
|
2369 | all the priorities, so having many of them (hundreds) uses a lot of space |
|
|
2370 | and time, so using the defaults of five priorities (-2 .. +2) is usually |
|
|
2371 | fine. |
|
|
2372 | |
|
|
2373 | If your embedding app does not need any priorities, defining these both to |
|
|
2374 | C<0> will save some memory and cpu. |
|
|
2375 | |
2067 | =item EV_PERIODIC_ENABLE |
2376 | =item EV_PERIODIC_ENABLE |
2068 | |
2377 | |
2069 | If undefined or defined to be C<1>, then periodic timers are supported. If |
2378 | If undefined or defined to be C<1>, then periodic timers are supported. If |
|
|
2379 | defined to be C<0>, then they are not. Disabling them saves a few kB of |
|
|
2380 | code. |
|
|
2381 | |
|
|
2382 | =item EV_IDLE_ENABLE |
|
|
2383 | |
|
|
2384 | If undefined or defined to be C<1>, then idle watchers are supported. If |
2070 | defined to be C<0>, then they are not. Disabling them saves a few kB of |
2385 | defined to be C<0>, then they are not. Disabling them saves a few kB of |
2071 | code. |
2386 | code. |
2072 | |
2387 | |
2073 | =item EV_EMBED_ENABLE |
2388 | =item EV_EMBED_ENABLE |
2074 | |
2389 | |
… | |
… | |
2129 | and the way callbacks are invoked and set. Must expand to a struct member |
2444 | and the way callbacks are invoked and set. Must expand to a struct member |
2130 | definition and a statement, respectively. See the F<ev.v> header file for |
2445 | definition and a statement, respectively. See the F<ev.v> header file for |
2131 | their default definitions. One possible use for overriding these is to |
2446 | their default definitions. One possible use for overriding these is to |
2132 | avoid the C<struct ev_loop *> as first argument in all cases, or to use |
2447 | avoid the C<struct ev_loop *> as first argument in all cases, or to use |
2133 | method calls instead of plain function calls in C++. |
2448 | method calls instead of plain function calls in C++. |
|
|
2449 | |
|
|
2450 | =head2 EXPORTED API SYMBOLS |
|
|
2451 | |
|
|
2452 | If you need to re-export the API (e.g. via a dll) and you need a list of |
|
|
2453 | exported symbols, you can use the provided F<Symbol.*> files which list |
|
|
2454 | all public symbols, one per line: |
|
|
2455 | |
|
|
2456 | Symbols.ev for libev proper |
|
|
2457 | Symbols.event for the libevent emulation |
|
|
2458 | |
|
|
2459 | This can also be used to rename all public symbols to avoid clashes with |
|
|
2460 | multiple versions of libev linked together (which is obviously bad in |
|
|
2461 | itself, but sometimes it is inconvinient to avoid this). |
|
|
2462 | |
|
|
2463 | A sed comamnd like this will create wrapper C<#define>'s that you need to |
|
|
2464 | include before including F<ev.h>: |
|
|
2465 | |
|
|
2466 | <Symbols.ev sed -e "s/.*/#define & myprefix_&/" >wrap.h |
|
|
2467 | |
|
|
2468 | This would create a file F<wrap.h> which essentially looks like this: |
|
|
2469 | |
|
|
2470 | #define ev_backend myprefix_ev_backend |
|
|
2471 | #define ev_check_start myprefix_ev_check_start |
|
|
2472 | #define ev_check_stop myprefix_ev_check_stop |
|
|
2473 | ... |
2134 | |
2474 | |
2135 | =head2 EXAMPLES |
2475 | =head2 EXAMPLES |
2136 | |
2476 | |
2137 | For a real-world example of a program the includes libev |
2477 | For a real-world example of a program the includes libev |
2138 | verbatim, you can have a look at the EV perl module |
2478 | verbatim, you can have a look at the EV perl module |
… | |
… | |
2141 | interface) and F<EV.xs> (implementation) files. Only the F<EV.xs> file |
2481 | interface) and F<EV.xs> (implementation) files. Only the F<EV.xs> file |
2142 | will be compiled. It is pretty complex because it provides its own header |
2482 | will be compiled. It is pretty complex because it provides its own header |
2143 | file. |
2483 | file. |
2144 | |
2484 | |
2145 | The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file |
2485 | The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file |
2146 | that everybody includes and which overrides some autoconf choices: |
2486 | that everybody includes and which overrides some configure choices: |
2147 | |
2487 | |
|
|
2488 | #define EV_MINIMAL 1 |
2148 | #define EV_USE_POLL 0 |
2489 | #define EV_USE_POLL 0 |
2149 | #define EV_MULTIPLICITY 0 |
2490 | #define EV_MULTIPLICITY 0 |
2150 | #define EV_PERIODICS 0 |
2491 | #define EV_PERIODIC_ENABLE 0 |
|
|
2492 | #define EV_STAT_ENABLE 0 |
|
|
2493 | #define EV_FORK_ENABLE 0 |
2151 | #define EV_CONFIG_H <config.h> |
2494 | #define EV_CONFIG_H <config.h> |
|
|
2495 | #define EV_MINPRI 0 |
|
|
2496 | #define EV_MAXPRI 0 |
2152 | |
2497 | |
2153 | #include "ev++.h" |
2498 | #include "ev++.h" |
2154 | |
2499 | |
2155 | And a F<ev_cpp.C> implementation file that contains libev proper and is compiled: |
2500 | And a F<ev_cpp.C> implementation file that contains libev proper and is compiled: |
2156 | |
2501 | |
… | |
… | |
2162 | |
2507 | |
2163 | In this section the complexities of (many of) the algorithms used inside |
2508 | In this section the complexities of (many of) the algorithms used inside |
2164 | libev will be explained. For complexity discussions about backends see the |
2509 | libev will be explained. For complexity discussions about backends see the |
2165 | documentation for C<ev_default_init>. |
2510 | documentation for C<ev_default_init>. |
2166 | |
2511 | |
|
|
2512 | All of the following are about amortised time: If an array needs to be |
|
|
2513 | extended, libev needs to realloc and move the whole array, but this |
|
|
2514 | happens asymptotically never with higher number of elements, so O(1) might |
|
|
2515 | mean it might do a lengthy realloc operation in rare cases, but on average |
|
|
2516 | it is much faster and asymptotically approaches constant time. |
|
|
2517 | |
2167 | =over 4 |
2518 | =over 4 |
2168 | |
2519 | |
2169 | =item Starting and stopping timer/periodic watchers: O(log skipped_other_timers) |
2520 | =item Starting and stopping timer/periodic watchers: O(log skipped_other_timers) |
2170 | |
2521 | |
|
|
2522 | This means that, when you have a watcher that triggers in one hour and |
|
|
2523 | there are 100 watchers that would trigger before that then inserting will |
|
|
2524 | have to skip those 100 watchers. |
|
|
2525 | |
2171 | =item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers) |
2526 | =item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers) |
2172 | |
2527 | |
|
|
2528 | That means that for changing a timer costs less than removing/adding them |
|
|
2529 | as only the relative motion in the event queue has to be paid for. |
|
|
2530 | |
2173 | =item Starting io/check/prepare/idle/signal/child watchers: O(1) |
2531 | =item Starting io/check/prepare/idle/signal/child watchers: O(1) |
2174 | |
2532 | |
|
|
2533 | These just add the watcher into an array or at the head of a list. |
2175 | =item Stopping check/prepare/idle watchers: O(1) |
2534 | =item Stopping check/prepare/idle watchers: O(1) |
2176 | |
2535 | |
2177 | =item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE)) |
2536 | =item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE)) |
2178 | |
2537 | |
|
|
2538 | These watchers are stored in lists then need to be walked to find the |
|
|
2539 | correct watcher to remove. The lists are usually short (you don't usually |
|
|
2540 | have many watchers waiting for the same fd or signal). |
|
|
2541 | |
2179 | =item Finding the next timer per loop iteration: O(1) |
2542 | =item Finding the next timer per loop iteration: O(1) |
2180 | |
2543 | |
2181 | =item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd) |
2544 | =item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd) |
2182 | |
2545 | |
|
|
2546 | A change means an I/O watcher gets started or stopped, which requires |
|
|
2547 | libev to recalculate its status (and possibly tell the kernel). |
|
|
2548 | |
2183 | =item Activating one watcher: O(1) |
2549 | =item Activating one watcher: O(1) |
2184 | |
2550 | |
|
|
2551 | =item Priority handling: O(number_of_priorities) |
|
|
2552 | |
|
|
2553 | Priorities are implemented by allocating some space for each |
|
|
2554 | priority. When doing priority-based operations, libev usually has to |
|
|
2555 | linearly search all the priorities. |
|
|
2556 | |
2185 | =back |
2557 | =back |
2186 | |
2558 | |
2187 | |
2559 | |
2188 | =head1 AUTHOR |
2560 | =head1 AUTHOR |
2189 | |
2561 | |