… | |
… | |
47 | |
47 | |
48 | return 0; |
48 | return 0; |
49 | } |
49 | } |
50 | |
50 | |
51 | =head1 DESCRIPTION |
51 | =head1 DESCRIPTION |
|
|
52 | |
|
|
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 | |
… | |
… | |
63 | details of the event, and then hand it over to libev by I<starting> the |
67 | details of the event, and then hand it over to libev by I<starting> the |
64 | watcher. |
68 | watcher. |
65 | |
69 | |
66 | =head1 FEATURES |
70 | =head1 FEATURES |
67 | |
71 | |
68 | Libev supports C<select>, C<poll>, the linux-specific C<epoll>, the |
72 | Libev supports C<select>, C<poll>, the Linux-specific C<epoll>, the |
69 | bsd-specific C<kqueue> and the solaris-specific event port mechanisms |
73 | BSD-specific C<kqueue> and the Solaris-specific event port mechanisms |
70 | for file descriptor events (C<ev_io>), relative timers (C<ev_timer>), |
74 | for file descriptor events (C<ev_io>), the Linux C<inotify> interface |
|
|
75 | (for C<ev_stat>), relative timers (C<ev_timer>), absolute timers |
71 | absolute timers with customised rescheduling (C<ev_periodic>), synchronous |
76 | with customised rescheduling (C<ev_periodic>), synchronous signals |
72 | signals (C<ev_signal>), process status change events (C<ev_child>), and |
77 | (C<ev_signal>), process status change events (C<ev_child>), and event |
73 | event watchers dealing with the event loop mechanism itself (C<ev_idle>, |
78 | watchers dealing with the event loop mechanism itself (C<ev_idle>, |
74 | C<ev_embed>, C<ev_prepare> and C<ev_check> watchers) as well as |
79 | C<ev_embed>, C<ev_prepare> and C<ev_check> watchers) as well as |
75 | file watchers (C<ev_stat>) and even limited support for fork events |
80 | file watchers (C<ev_stat>) and even limited support for fork events |
76 | (C<ev_fork>). |
81 | (C<ev_fork>). |
77 | |
82 | |
78 | It also is quite fast (see this |
83 | It also is quite fast (see this |
… | |
… | |
162 | C<ev_embeddable_backends () & ev_supported_backends ()>, likewise for |
167 | C<ev_embeddable_backends () & ev_supported_backends ()>, likewise for |
163 | recommended ones. |
168 | recommended ones. |
164 | |
169 | |
165 | See the description of C<ev_embed> watchers for more info. |
170 | See the description of C<ev_embed> watchers for more info. |
166 | |
171 | |
167 | =item ev_set_allocator (void *(*cb)(void *ptr, size_t size)) |
172 | =item ev_set_allocator (void *(*cb)(void *ptr, long size)) |
168 | |
173 | |
169 | Sets the allocation function to use (the prototype and semantics are |
174 | Sets the allocation function to use (the prototype is similar - the |
170 | identical to the realloc C function). It is used to allocate and free |
175 | semantics is identical - to the realloc C function). It is used to |
171 | memory (no surprises here). If it returns zero when memory needs to be |
176 | allocate and free memory (no surprises here). If it returns zero when |
172 | allocated, the library might abort or take some potentially destructive |
177 | memory needs to be allocated, the library might abort or take some |
173 | action. The default is your system realloc function. |
178 | potentially destructive action. The default is your system realloc |
|
|
179 | function. |
174 | |
180 | |
175 | You could override this function in high-availability programs to, say, |
181 | You could override this function in high-availability programs to, say, |
176 | free some memory if it cannot allocate memory, to use a special allocator, |
182 | free some memory if it cannot allocate memory, to use a special allocator, |
177 | or even to sleep a while and retry until some memory is available. |
183 | or even to sleep a while and retry until some memory is available. |
178 | |
184 | |
… | |
… | |
264 | C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will |
270 | C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will |
265 | override the flags completely if it is found in the environment. This is |
271 | override the flags completely if it is found in the environment. This is |
266 | useful to try out specific backends to test their performance, or to work |
272 | useful to try out specific backends to test their performance, or to work |
267 | around bugs. |
273 | around bugs. |
268 | |
274 | |
|
|
275 | =item C<EVFLAG_FORKCHECK> |
|
|
276 | |
|
|
277 | Instead of calling C<ev_default_fork> or C<ev_loop_fork> manually after |
|
|
278 | a fork, you can also make libev check for a fork in each iteration by |
|
|
279 | enabling this flag. |
|
|
280 | |
|
|
281 | This works by calling C<getpid ()> on every iteration of the loop, |
|
|
282 | and thus this might slow down your event loop if you do a lot of loop |
|
|
283 | iterations and little real work, but is usually not noticeable (on my |
|
|
284 | Linux system for example, C<getpid> is actually a simple 5-insn sequence |
|
|
285 | without a syscall and thus I<very> fast, but my Linux system also has |
|
|
286 | C<pthread_atfork> which is even faster). |
|
|
287 | |
|
|
288 | The big advantage of this flag is that you can forget about fork (and |
|
|
289 | forget about forgetting to tell libev about forking) when you use this |
|
|
290 | flag. |
|
|
291 | |
|
|
292 | This flag setting cannot be overriden or specified in the C<LIBEV_FLAGS> |
|
|
293 | environment variable. |
|
|
294 | |
269 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
295 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
270 | |
296 | |
271 | This is your standard select(2) backend. Not I<completely> standard, as |
297 | This is your standard select(2) backend. Not I<completely> standard, as |
272 | libev tries to roll its own fd_set with no limits on the number of fds, |
298 | libev tries to roll its own fd_set with no limits on the number of fds, |
273 | but if that fails, expect a fairly low limit on the number of fds when |
299 | but if that fails, expect a fairly low limit on the number of fds when |
… | |
… | |
407 | =item ev_loop_fork (loop) |
433 | =item ev_loop_fork (loop) |
408 | |
434 | |
409 | Like C<ev_default_fork>, but acts on an event loop created by |
435 | Like C<ev_default_fork>, but acts on an event loop created by |
410 | C<ev_loop_new>. Yes, you have to call this on every allocated event loop |
436 | C<ev_loop_new>. Yes, you have to call this on every allocated event loop |
411 | after fork, and how you do this is entirely your own problem. |
437 | after fork, and how you do this is entirely your own problem. |
|
|
438 | |
|
|
439 | =item unsigned int ev_loop_count (loop) |
|
|
440 | |
|
|
441 | Returns the count of loop iterations for the loop, which is identical to |
|
|
442 | the number of times libev did poll for new events. It starts at C<0> and |
|
|
443 | happily wraps around with enough iterations. |
|
|
444 | |
|
|
445 | This value can sometimes be useful as a generation counter of sorts (it |
|
|
446 | "ticks" the number of loop iterations), as it roughly corresponds with |
|
|
447 | C<ev_prepare> and C<ev_check> calls. |
412 | |
448 | |
413 | =item unsigned int ev_backend (loop) |
449 | =item unsigned int ev_backend (loop) |
414 | |
450 | |
415 | Returns one of the C<EVBACKEND_*> flags indicating the event backend in |
451 | Returns one of the C<EVBACKEND_*> flags indicating the event backend in |
416 | use. |
452 | use. |
… | |
… | |
700 | =item bool ev_is_pending (ev_TYPE *watcher) |
736 | =item bool ev_is_pending (ev_TYPE *watcher) |
701 | |
737 | |
702 | Returns a true value iff the watcher is pending, (i.e. it has outstanding |
738 | Returns a true value iff the watcher is pending, (i.e. it has outstanding |
703 | events but its callback has not yet been invoked). As long as a watcher |
739 | events but its callback has not yet been invoked). As long as a watcher |
704 | is pending (but not active) you must not call an init function on it (but |
740 | is pending (but not active) you must not call an init function on it (but |
705 | C<ev_TYPE_set> is safe) and you must make sure the watcher is available to |
741 | C<ev_TYPE_set> is safe), you must not change its priority, and you must |
706 | libev (e.g. you cnanot C<free ()> it). |
742 | make sure the watcher is available to libev (e.g. you cannot C<free ()> |
|
|
743 | it). |
707 | |
744 | |
708 | =item callback = ev_cb (ev_TYPE *watcher) |
745 | =item callback ev_cb (ev_TYPE *watcher) |
709 | |
746 | |
710 | Returns the callback currently set on the watcher. |
747 | Returns the callback currently set on the watcher. |
711 | |
748 | |
712 | =item ev_cb_set (ev_TYPE *watcher, callback) |
749 | =item ev_cb_set (ev_TYPE *watcher, callback) |
713 | |
750 | |
714 | Change the callback. You can change the callback at virtually any time |
751 | Change the callback. You can change the callback at virtually any time |
715 | (modulo threads). |
752 | (modulo threads). |
|
|
753 | |
|
|
754 | =item ev_set_priority (ev_TYPE *watcher, priority) |
|
|
755 | |
|
|
756 | =item int ev_priority (ev_TYPE *watcher) |
|
|
757 | |
|
|
758 | Set and query the priority of the watcher. The priority is a small |
|
|
759 | integer between C<EV_MAXPRI> (default: C<2>) and C<EV_MINPRI> |
|
|
760 | (default: C<-2>). Pending watchers with higher priority will be invoked |
|
|
761 | before watchers with lower priority, but priority will not keep watchers |
|
|
762 | from being executed (except for C<ev_idle> watchers). |
|
|
763 | |
|
|
764 | This means that priorities are I<only> used for ordering callback |
|
|
765 | invocation after new events have been received. This is useful, for |
|
|
766 | example, to reduce latency after idling, or more often, to bind two |
|
|
767 | watchers on the same event and make sure one is called first. |
|
|
768 | |
|
|
769 | If you need to suppress invocation when higher priority events are pending |
|
|
770 | you need to look at C<ev_idle> watchers, which provide this functionality. |
|
|
771 | |
|
|
772 | You I<must not> change the priority of a watcher as long as it is active or |
|
|
773 | pending. |
|
|
774 | |
|
|
775 | The default priority used by watchers when no priority has been set is |
|
|
776 | always C<0>, which is supposed to not be too high and not be too low :). |
|
|
777 | |
|
|
778 | Setting a priority outside the range of C<EV_MINPRI> to C<EV_MAXPRI> is |
|
|
779 | fine, as long as you do not mind that the priority value you query might |
|
|
780 | or might not have been adjusted to be within valid range. |
716 | |
781 | |
717 | =back |
782 | =back |
718 | |
783 | |
719 | |
784 | |
720 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
785 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
… | |
… | |
741 | { |
806 | { |
742 | struct my_io *w = (struct my_io *)w_; |
807 | struct my_io *w = (struct my_io *)w_; |
743 | ... |
808 | ... |
744 | } |
809 | } |
745 | |
810 | |
746 | More interesting and less C-conformant ways of catsing your callback type |
811 | More interesting and less C-conformant ways of casting your callback type |
747 | have been omitted.... |
812 | instead have been omitted. |
|
|
813 | |
|
|
814 | Another common scenario is having some data structure with multiple |
|
|
815 | watchers: |
|
|
816 | |
|
|
817 | struct my_biggy |
|
|
818 | { |
|
|
819 | int some_data; |
|
|
820 | ev_timer t1; |
|
|
821 | ev_timer t2; |
|
|
822 | } |
|
|
823 | |
|
|
824 | In this case getting the pointer to C<my_biggy> is a bit more complicated, |
|
|
825 | you need to use C<offsetof>: |
|
|
826 | |
|
|
827 | #include <stddef.h> |
|
|
828 | |
|
|
829 | static void |
|
|
830 | t1_cb (EV_P_ struct ev_timer *w, int revents) |
|
|
831 | { |
|
|
832 | struct my_biggy big = (struct my_biggy * |
|
|
833 | (((char *)w) - offsetof (struct my_biggy, t1)); |
|
|
834 | } |
|
|
835 | |
|
|
836 | static void |
|
|
837 | t2_cb (EV_P_ struct ev_timer *w, int revents) |
|
|
838 | { |
|
|
839 | struct my_biggy big = (struct my_biggy * |
|
|
840 | (((char *)w) - offsetof (struct my_biggy, t2)); |
|
|
841 | } |
748 | |
842 | |
749 | |
843 | |
750 | =head1 WATCHER TYPES |
844 | =head1 WATCHER TYPES |
751 | |
845 | |
752 | This section describes each watcher in detail, but will not repeat |
846 | This section describes each watcher in detail, but will not repeat |
… | |
… | |
797 | it is best to always use non-blocking I/O: An extra C<read>(2) returning |
891 | it is best to always use non-blocking I/O: An extra C<read>(2) returning |
798 | C<EAGAIN> is far preferable to a program hanging until some data arrives. |
892 | C<EAGAIN> is far preferable to a program hanging until some data arrives. |
799 | |
893 | |
800 | If you cannot run the fd in non-blocking mode (for example you should not |
894 | If you cannot run the fd in non-blocking mode (for example you should not |
801 | play around with an Xlib connection), then you have to seperately re-test |
895 | play around with an Xlib connection), then you have to seperately re-test |
802 | wether a file descriptor is really ready with a known-to-be good interface |
896 | whether a file descriptor is really ready with a known-to-be good interface |
803 | such as poll (fortunately in our Xlib example, Xlib already does this on |
897 | such as poll (fortunately in our Xlib example, Xlib already does this on |
804 | its own, so its quite safe to use). |
898 | its own, so its quite safe to use). |
805 | |
899 | |
806 | =over 4 |
900 | =over 4 |
807 | |
901 | |
… | |
… | |
885 | =item ev_timer_again (loop) |
979 | =item ev_timer_again (loop) |
886 | |
980 | |
887 | This will act as if the timer timed out and restart it again if it is |
981 | This will act as if the timer timed out and restart it again if it is |
888 | repeating. The exact semantics are: |
982 | repeating. The exact semantics are: |
889 | |
983 | |
|
|
984 | If the timer is pending, its pending status is cleared. |
|
|
985 | |
890 | If the timer is started but nonrepeating, stop it. |
986 | If the timer is started but nonrepeating, stop it (as if it timed out). |
891 | |
987 | |
892 | If the timer is repeating, either start it if necessary (with the repeat |
988 | If the timer is repeating, either start it if necessary (with the |
893 | value), or reset the running timer to the repeat value. |
989 | C<repeat> value), or reset the running timer to the C<repeat> value. |
894 | |
990 | |
895 | This sounds a bit complicated, but here is a useful and typical |
991 | This sounds a bit complicated, but here is a useful and typical |
896 | example: Imagine you have a tcp connection and you want a so-called |
992 | example: Imagine you have a tcp connection and you want a so-called idle |
897 | idle timeout, that is, you want to be called when there have been, |
993 | timeout, that is, you want to be called when there have been, say, 60 |
898 | say, 60 seconds of inactivity on the socket. The easiest way to do |
994 | seconds of inactivity on the socket. The easiest way to do this is to |
899 | this is to configure an C<ev_timer> with C<after>=C<repeat>=C<60> and calling |
995 | configure an C<ev_timer> with a C<repeat> value of C<60> and then call |
900 | C<ev_timer_again> each time you successfully read or write some data. If |
996 | C<ev_timer_again> each time you successfully read or write some data. If |
901 | you go into an idle state where you do not expect data to travel on the |
997 | you go into an idle state where you do not expect data to travel on the |
902 | socket, you can stop the timer, and again will automatically restart it if |
998 | socket, you can C<ev_timer_stop> the timer, and C<ev_timer_again> will |
903 | need be. |
999 | automatically restart it if need be. |
904 | |
1000 | |
905 | You can also ignore the C<after> value and C<ev_timer_start> altogether |
1001 | That means you can ignore the C<after> value and C<ev_timer_start> |
906 | and only ever use the C<repeat> value: |
1002 | altogether and only ever use the C<repeat> value and C<ev_timer_again>: |
907 | |
1003 | |
908 | ev_timer_init (timer, callback, 0., 5.); |
1004 | ev_timer_init (timer, callback, 0., 5.); |
909 | ev_timer_again (loop, timer); |
1005 | ev_timer_again (loop, timer); |
910 | ... |
1006 | ... |
911 | timer->again = 17.; |
1007 | timer->again = 17.; |
912 | ev_timer_again (loop, timer); |
1008 | ev_timer_again (loop, timer); |
913 | ... |
1009 | ... |
914 | timer->again = 10.; |
1010 | timer->again = 10.; |
915 | ev_timer_again (loop, timer); |
1011 | ev_timer_again (loop, timer); |
916 | |
1012 | |
917 | This is more efficient then stopping/starting the timer eahc time you want |
1013 | This is more slightly efficient then stopping/starting the timer each time |
918 | to modify its timeout value. |
1014 | you want to modify its timeout value. |
919 | |
1015 | |
920 | =item ev_tstamp repeat [read-write] |
1016 | =item ev_tstamp repeat [read-write] |
921 | |
1017 | |
922 | The current C<repeat> value. Will be used each time the watcher times out |
1018 | The current C<repeat> value. Will be used each time the watcher times out |
923 | or C<ev_timer_again> is called and determines the next timeout (if any), |
1019 | or C<ev_timer_again> is called and determines the next timeout (if any), |
… | |
… | |
1192 | not exist" is a status change like any other. The condition "path does |
1288 | not exist" is a status change like any other. The condition "path does |
1193 | not exist" is signified by the C<st_nlink> field being zero (which is |
1289 | not exist" is signified by the C<st_nlink> field being zero (which is |
1194 | otherwise always forced to be at least one) and all the other fields of |
1290 | otherwise always forced to be at least one) and all the other fields of |
1195 | the stat buffer having unspecified contents. |
1291 | the stat buffer having unspecified contents. |
1196 | |
1292 | |
|
|
1293 | The path I<should> be absolute and I<must not> end in a slash. If it is |
|
|
1294 | relative and your working directory changes, the behaviour is undefined. |
|
|
1295 | |
1197 | Since there is no standard to do this, the portable implementation simply |
1296 | Since there is no standard to do this, the portable implementation simply |
1198 | calls C<stat (2)> regulalry on the path to see if it changed somehow. You |
1297 | calls C<stat (2)> regularly on the path to see if it changed somehow. You |
1199 | can specify a recommended polling interval for this case. If you specify |
1298 | can specify a recommended polling interval for this case. If you specify |
1200 | a polling interval of C<0> (highly recommended!) then a I<suitable, |
1299 | a polling interval of C<0> (highly recommended!) then a I<suitable, |
1201 | unspecified default> value will be used (which you can expect to be around |
1300 | unspecified default> value will be used (which you can expect to be around |
1202 | five seconds, although this might change dynamically). Libev will also |
1301 | five seconds, although this might change dynamically). Libev will also |
1203 | impose a minimum interval which is currently around C<0.1>, but thats |
1302 | impose a minimum interval which is currently around C<0.1>, but thats |
… | |
… | |
1205 | |
1304 | |
1206 | This watcher type is not meant for massive numbers of stat watchers, |
1305 | This watcher type is not meant for massive numbers of stat watchers, |
1207 | as even with OS-supported change notifications, this can be |
1306 | as even with OS-supported change notifications, this can be |
1208 | resource-intensive. |
1307 | resource-intensive. |
1209 | |
1308 | |
1210 | At the time of this writing, no specific OS backends are implemented, but |
1309 | At the time of this writing, only the Linux inotify interface is |
1211 | if demand increases, at least a kqueue and inotify backend will be added. |
1310 | implemented (implementing kqueue support is left as an exercise for the |
|
|
1311 | reader). Inotify will be used to give hints only and should not change the |
|
|
1312 | semantics of C<ev_stat> watchers, which means that libev sometimes needs |
|
|
1313 | to fall back to regular polling again even with inotify, but changes are |
|
|
1314 | usually detected immediately, and if the file exists there will be no |
|
|
1315 | polling. |
1212 | |
1316 | |
1213 | =over 4 |
1317 | =over 4 |
1214 | |
1318 | |
1215 | =item ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval) |
1319 | =item ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval) |
1216 | |
1320 | |
… | |
… | |
1280 | ev_stat_start (loop, &passwd); |
1384 | ev_stat_start (loop, &passwd); |
1281 | |
1385 | |
1282 | |
1386 | |
1283 | =head2 C<ev_idle> - when you've got nothing better to do... |
1387 | =head2 C<ev_idle> - when you've got nothing better to do... |
1284 | |
1388 | |
1285 | Idle watchers trigger events when there are no other events are pending |
1389 | Idle watchers trigger events when no other events of the same or higher |
1286 | (prepare, check and other idle watchers do not count). That is, as long |
1390 | priority are pending (prepare, check and other idle watchers do not |
1287 | as your process is busy handling sockets or timeouts (or even signals, |
1391 | count). |
1288 | imagine) it will not be triggered. But when your process is idle all idle |
1392 | |
1289 | watchers are being called again and again, once per event loop iteration - |
1393 | That is, as long as your process is busy handling sockets or timeouts |
|
|
1394 | (or even signals, imagine) of the same or higher priority it will not be |
|
|
1395 | triggered. But when your process is idle (or only lower-priority watchers |
|
|
1396 | are pending), the idle watchers are being called once per event loop |
1290 | until stopped, that is, or your process receives more events and becomes |
1397 | iteration - until stopped, that is, or your process receives more events |
1291 | busy. |
1398 | and becomes busy again with higher priority stuff. |
1292 | |
1399 | |
1293 | The most noteworthy effect is that as long as any idle watchers are |
1400 | The most noteworthy effect is that as long as any idle watchers are |
1294 | active, the process will not block when waiting for new events. |
1401 | active, the process will not block when waiting for new events. |
1295 | |
1402 | |
1296 | Apart from keeping your process non-blocking (which is a useful |
1403 | Apart from keeping your process non-blocking (which is a useful |
… | |
… | |
1396 | |
1503 | |
1397 | // create io watchers for each fd and a timer before blocking |
1504 | // create io watchers for each fd and a timer before blocking |
1398 | static void |
1505 | static void |
1399 | adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) |
1506 | adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) |
1400 | { |
1507 | { |
1401 | int timeout = 3600000;truct pollfd fds [nfd]; |
1508 | int timeout = 3600000; |
|
|
1509 | struct pollfd fds [nfd]; |
1402 | // actual code will need to loop here and realloc etc. |
1510 | // actual code will need to loop here and realloc etc. |
1403 | adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
1511 | adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ())); |
1404 | |
1512 | |
1405 | /* the callback is illegal, but won't be called as we stop during check */ |
1513 | /* the callback is illegal, but won't be called as we stop during check */ |
1406 | ev_timer_init (&tw, 0, timeout * 1e-3); |
1514 | ev_timer_init (&tw, 0, timeout * 1e-3); |
… | |
… | |
1640 | |
1748 | |
1641 | To use it, |
1749 | To use it, |
1642 | |
1750 | |
1643 | #include <ev++.h> |
1751 | #include <ev++.h> |
1644 | |
1752 | |
1645 | (it is not installed by default). This automatically includes F<ev.h> |
1753 | This automatically includes F<ev.h> and puts all of its definitions (many |
1646 | and puts all of its definitions (many of them macros) into the global |
1754 | of them macros) into the global namespace. All C++ specific things are |
1647 | namespace. All C++ specific things are put into the C<ev> namespace. |
1755 | put into the C<ev> namespace. It should support all the same embedding |
|
|
1756 | options as F<ev.h>, most notably C<EV_MULTIPLICITY>. |
1648 | |
1757 | |
1649 | It should support all the same embedding options as F<ev.h>, most notably |
1758 | Care has been taken to keep the overhead low. The only data member the C++ |
1650 | C<EV_MULTIPLICITY>. |
1759 | classes add (compared to plain C-style watchers) is the event loop pointer |
|
|
1760 | that the watcher is associated with (or no additional members at all if |
|
|
1761 | you disable C<EV_MULTIPLICITY> when embedding libev). |
|
|
1762 | |
|
|
1763 | Currently, functions, and static and non-static member functions can be |
|
|
1764 | used as callbacks. Other types should be easy to add as long as they only |
|
|
1765 | need one additional pointer for context. If you need support for other |
|
|
1766 | types of functors please contact the author (preferably after implementing |
|
|
1767 | it). |
1651 | |
1768 | |
1652 | Here is a list of things available in the C<ev> namespace: |
1769 | Here is a list of things available in the C<ev> namespace: |
1653 | |
1770 | |
1654 | =over 4 |
1771 | =over 4 |
1655 | |
1772 | |
… | |
… | |
1671 | |
1788 | |
1672 | All of those classes have these methods: |
1789 | All of those classes have these methods: |
1673 | |
1790 | |
1674 | =over 4 |
1791 | =over 4 |
1675 | |
1792 | |
1676 | =item ev::TYPE::TYPE (object *, object::method *) |
1793 | =item ev::TYPE::TYPE () |
1677 | |
1794 | |
1678 | =item ev::TYPE::TYPE (object *, object::method *, struct ev_loop *) |
1795 | =item ev::TYPE::TYPE (struct ev_loop *) |
1679 | |
1796 | |
1680 | =item ev::TYPE::~TYPE |
1797 | =item ev::TYPE::~TYPE |
1681 | |
1798 | |
1682 | The constructor takes a pointer to an object and a method pointer to |
1799 | The constructor (optionally) takes an event loop to associate the watcher |
1683 | the event handler callback to call in this class. The constructor calls |
1800 | with. If it is omitted, it will use C<EV_DEFAULT>. |
1684 | C<ev_init> for you, which means you have to call the C<set> method |
1801 | |
1685 | before starting it. If you do not specify a loop then the constructor |
1802 | The constructor calls C<ev_init> for you, which means you have to call the |
1686 | automatically associates the default loop with this watcher. |
1803 | C<set> method before starting it. |
|
|
1804 | |
|
|
1805 | It will not set a callback, however: You have to call the templated C<set> |
|
|
1806 | method to set a callback before you can start the watcher. |
|
|
1807 | |
|
|
1808 | (The reason why you have to use a method is a limitation in C++ which does |
|
|
1809 | not allow explicit template arguments for constructors). |
1687 | |
1810 | |
1688 | The destructor automatically stops the watcher if it is active. |
1811 | The destructor automatically stops the watcher if it is active. |
|
|
1812 | |
|
|
1813 | =item w->set<class, &class::method> (object *) |
|
|
1814 | |
|
|
1815 | This method sets the callback method to call. The method has to have a |
|
|
1816 | signature of C<void (*)(ev_TYPE &, int)>, it receives the watcher as |
|
|
1817 | first argument and the C<revents> as second. The object must be given as |
|
|
1818 | parameter and is stored in the C<data> member of the watcher. |
|
|
1819 | |
|
|
1820 | This method synthesizes efficient thunking code to call your method from |
|
|
1821 | the C callback that libev requires. If your compiler can inline your |
|
|
1822 | callback (i.e. it is visible to it at the place of the C<set> call and |
|
|
1823 | your compiler is good :), then the method will be fully inlined into the |
|
|
1824 | thunking function, making it as fast as a direct C callback. |
|
|
1825 | |
|
|
1826 | Example: simple class declaration and watcher initialisation |
|
|
1827 | |
|
|
1828 | struct myclass |
|
|
1829 | { |
|
|
1830 | void io_cb (ev::io &w, int revents) { } |
|
|
1831 | } |
|
|
1832 | |
|
|
1833 | myclass obj; |
|
|
1834 | ev::io iow; |
|
|
1835 | iow.set <myclass, &myclass::io_cb> (&obj); |
|
|
1836 | |
|
|
1837 | =item w->set (void (*function)(watcher &w, int), void *data = 0) |
|
|
1838 | |
|
|
1839 | Also sets a callback, but uses a static method or plain function as |
|
|
1840 | callback. The optional C<data> argument will be stored in the watcher's |
|
|
1841 | C<data> member and is free for you to use. |
|
|
1842 | |
|
|
1843 | See the method-C<set> above for more details. |
1689 | |
1844 | |
1690 | =item w->set (struct ev_loop *) |
1845 | =item w->set (struct ev_loop *) |
1691 | |
1846 | |
1692 | Associates a different C<struct ev_loop> with this watcher. You can only |
1847 | Associates a different C<struct ev_loop> with this watcher. You can only |
1693 | do this when the watcher is inactive (and not pending either). |
1848 | do this when the watcher is inactive (and not pending either). |
1694 | |
1849 | |
1695 | =item w->set ([args]) |
1850 | =item w->set ([args]) |
1696 | |
1851 | |
1697 | Basically the same as C<ev_TYPE_set>, with the same args. Must be |
1852 | Basically the same as C<ev_TYPE_set>, with the same args. Must be |
1698 | called at least once. Unlike the C counterpart, an active watcher gets |
1853 | called at least once. Unlike the C counterpart, an active watcher gets |
1699 | automatically stopped and restarted. |
1854 | automatically stopped and restarted when reconfiguring it with this |
|
|
1855 | method. |
1700 | |
1856 | |
1701 | =item w->start () |
1857 | =item w->start () |
1702 | |
1858 | |
1703 | Starts the watcher. Note that there is no C<loop> argument as the |
1859 | Starts the watcher. Note that there is no C<loop> argument, as the |
1704 | constructor already takes the loop. |
1860 | constructor already stores the event loop. |
1705 | |
1861 | |
1706 | =item w->stop () |
1862 | =item w->stop () |
1707 | |
1863 | |
1708 | Stops the watcher if it is active. Again, no C<loop> argument. |
1864 | Stops the watcher if it is active. Again, no C<loop> argument. |
1709 | |
1865 | |
… | |
… | |
1734 | |
1890 | |
1735 | myclass (); |
1891 | myclass (); |
1736 | } |
1892 | } |
1737 | |
1893 | |
1738 | myclass::myclass (int fd) |
1894 | myclass::myclass (int fd) |
1739 | : io (this, &myclass::io_cb), |
|
|
1740 | idle (this, &myclass::idle_cb) |
|
|
1741 | { |
1895 | { |
|
|
1896 | io .set <myclass, &myclass::io_cb > (this); |
|
|
1897 | idle.set <myclass, &myclass::idle_cb> (this); |
|
|
1898 | |
1742 | io.start (fd, ev::READ); |
1899 | io.start (fd, ev::READ); |
1743 | } |
1900 | } |
1744 | |
1901 | |
1745 | |
1902 | |
1746 | =head1 MACRO MAGIC |
1903 | =head1 MACRO MAGIC |
1747 | |
1904 | |
1748 | Libev can be compiled with a variety of options, the most fundemantal is |
1905 | Libev can be compiled with a variety of options, the most fundemantal is |
1749 | C<EV_MULTIPLICITY>. This option determines wether (most) functions and |
1906 | C<EV_MULTIPLICITY>. This option determines whether (most) functions and |
1750 | callbacks have an initial C<struct ev_loop *> argument. |
1907 | callbacks have an initial C<struct ev_loop *> argument. |
1751 | |
1908 | |
1752 | To make it easier to write programs that cope with either variant, the |
1909 | To make it easier to write programs that cope with either variant, the |
1753 | following macros are defined: |
1910 | following macros are defined: |
1754 | |
1911 | |
… | |
… | |
1787 | Similar to the other two macros, this gives you the value of the default |
1944 | Similar to the other two macros, this gives you the value of the default |
1788 | loop, if multiple loops are supported ("ev loop default"). |
1945 | loop, if multiple loops are supported ("ev loop default"). |
1789 | |
1946 | |
1790 | =back |
1947 | =back |
1791 | |
1948 | |
1792 | Example: Declare and initialise a check watcher, working regardless of |
1949 | Example: Declare and initialise a check watcher, utilising the above |
1793 | wether multiple loops are supported or not. |
1950 | macros so it will work regardless of whether multiple loops are supported |
|
|
1951 | or not. |
1794 | |
1952 | |
1795 | static void |
1953 | static void |
1796 | check_cb (EV_P_ ev_timer *w, int revents) |
1954 | check_cb (EV_P_ ev_timer *w, int revents) |
1797 | { |
1955 | { |
1798 | ev_check_stop (EV_A_ w); |
1956 | ev_check_stop (EV_A_ w); |
… | |
… | |
1800 | |
1958 | |
1801 | ev_check check; |
1959 | ev_check check; |
1802 | ev_check_init (&check, check_cb); |
1960 | ev_check_init (&check, check_cb); |
1803 | ev_check_start (EV_DEFAULT_ &check); |
1961 | ev_check_start (EV_DEFAULT_ &check); |
1804 | ev_loop (EV_DEFAULT_ 0); |
1962 | ev_loop (EV_DEFAULT_ 0); |
1805 | |
|
|
1806 | |
1963 | |
1807 | =head1 EMBEDDING |
1964 | =head1 EMBEDDING |
1808 | |
1965 | |
1809 | Libev can (and often is) directly embedded into host |
1966 | Libev can (and often is) directly embedded into host |
1810 | applications. Examples of applications that embed it include the Deliantra |
1967 | applications. Examples of applications that embed it include the Deliantra |
… | |
… | |
1850 | ev_vars.h |
2007 | ev_vars.h |
1851 | ev_wrap.h |
2008 | ev_wrap.h |
1852 | |
2009 | |
1853 | ev_win32.c required on win32 platforms only |
2010 | ev_win32.c required on win32 platforms only |
1854 | |
2011 | |
1855 | ev_select.c only when select backend is enabled (which is by default) |
2012 | ev_select.c only when select backend is enabled (which is enabled by default) |
1856 | ev_poll.c only when poll backend is enabled (disabled by default) |
2013 | ev_poll.c only when poll backend is enabled (disabled by default) |
1857 | ev_epoll.c only when the epoll backend is enabled (disabled by default) |
2014 | ev_epoll.c only when the epoll backend is enabled (disabled by default) |
1858 | ev_kqueue.c only when the kqueue backend is enabled (disabled by default) |
2015 | ev_kqueue.c only when the kqueue backend is enabled (disabled by default) |
1859 | ev_port.c only when the solaris port backend is enabled (disabled by default) |
2016 | ev_port.c only when the solaris port backend is enabled (disabled by default) |
1860 | |
2017 | |
… | |
… | |
1985 | |
2142 | |
1986 | =item EV_USE_DEVPOLL |
2143 | =item EV_USE_DEVPOLL |
1987 | |
2144 | |
1988 | reserved for future expansion, works like the USE symbols above. |
2145 | reserved for future expansion, works like the USE symbols above. |
1989 | |
2146 | |
|
|
2147 | =item EV_USE_INOTIFY |
|
|
2148 | |
|
|
2149 | If defined to be C<1>, libev will compile in support for the Linux inotify |
|
|
2150 | interface to speed up C<ev_stat> watchers. Its actual availability will |
|
|
2151 | be detected at runtime. |
|
|
2152 | |
1990 | =item EV_H |
2153 | =item EV_H |
1991 | |
2154 | |
1992 | The name of the F<ev.h> header file used to include it. The default if |
2155 | The name of the F<ev.h> header file used to include it. The default if |
1993 | undefined is C<< <ev.h> >> in F<event.h> and C<"ev.h"> in F<ev.c>. This |
2156 | undefined is C<< <ev.h> >> in F<event.h> and C<"ev.h"> in F<ev.c>. This |
1994 | can be used to virtually rename the F<ev.h> header file in case of conflicts. |
2157 | can be used to virtually rename the F<ev.h> header file in case of conflicts. |
… | |
… | |
2017 | will have the C<struct ev_loop *> as first argument, and you can create |
2180 | will have the C<struct ev_loop *> as first argument, and you can create |
2018 | additional independent event loops. Otherwise there will be no support |
2181 | additional independent event loops. Otherwise there will be no support |
2019 | for multiple event loops and there is no first event loop pointer |
2182 | for multiple event loops and there is no first event loop pointer |
2020 | argument. Instead, all functions act on the single default loop. |
2183 | argument. Instead, all functions act on the single default loop. |
2021 | |
2184 | |
|
|
2185 | =item EV_MINPRI |
|
|
2186 | |
|
|
2187 | =item EV_MAXPRI |
|
|
2188 | |
|
|
2189 | The range of allowed priorities. C<EV_MINPRI> must be smaller or equal to |
|
|
2190 | C<EV_MAXPRI>, but otherwise there are no non-obvious limitations. You can |
|
|
2191 | provide for more priorities by overriding those symbols (usually defined |
|
|
2192 | to be C<-2> and C<2>, respectively). |
|
|
2193 | |
|
|
2194 | When doing priority-based operations, libev usually has to linearly search |
|
|
2195 | all the priorities, so having many of them (hundreds) uses a lot of space |
|
|
2196 | and time, so using the defaults of five priorities (-2 .. +2) is usually |
|
|
2197 | fine. |
|
|
2198 | |
|
|
2199 | If your embedding app does not need any priorities, defining these both to |
|
|
2200 | C<0> will save some memory and cpu. |
|
|
2201 | |
2022 | =item EV_PERIODIC_ENABLE |
2202 | =item EV_PERIODIC_ENABLE |
2023 | |
2203 | |
2024 | If undefined or defined to be C<1>, then periodic timers are supported. If |
2204 | If undefined or defined to be C<1>, then periodic timers are supported. If |
2025 | defined to be C<0>, then they are not. Disabling them saves a few kB of |
2205 | defined to be C<0>, then they are not. Disabling them saves a few kB of |
2026 | code. |
2206 | code. |
2027 | |
2207 | |
|
|
2208 | =item EV_IDLE_ENABLE |
|
|
2209 | |
|
|
2210 | If undefined or defined to be C<1>, then idle watchers are supported. If |
|
|
2211 | defined to be C<0>, then they are not. Disabling them saves a few kB of |
|
|
2212 | code. |
|
|
2213 | |
2028 | =item EV_EMBED_ENABLE |
2214 | =item EV_EMBED_ENABLE |
2029 | |
2215 | |
2030 | If undefined or defined to be C<1>, then embed watchers are supported. If |
2216 | If undefined or defined to be C<1>, then embed watchers are supported. If |
2031 | defined to be C<0>, then they are not. |
2217 | defined to be C<0>, then they are not. |
2032 | |
2218 | |
… | |
… | |
2049 | =item EV_PID_HASHSIZE |
2235 | =item EV_PID_HASHSIZE |
2050 | |
2236 | |
2051 | C<ev_child> watchers use a small hash table to distribute workload by |
2237 | C<ev_child> watchers use a small hash table to distribute workload by |
2052 | pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more |
2238 | pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more |
2053 | than enough. If you need to manage thousands of children you might want to |
2239 | than enough. If you need to manage thousands of children you might want to |
2054 | increase this value. |
2240 | increase this value (I<must> be a power of two). |
|
|
2241 | |
|
|
2242 | =item EV_INOTIFY_HASHSIZE |
|
|
2243 | |
|
|
2244 | C<ev_staz> watchers use a small hash table to distribute workload by |
|
|
2245 | inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>), |
|
|
2246 | usually more than enough. If you need to manage thousands of C<ev_stat> |
|
|
2247 | watchers you might want to increase this value (I<must> be a power of |
|
|
2248 | two). |
2055 | |
2249 | |
2056 | =item EV_COMMON |
2250 | =item EV_COMMON |
2057 | |
2251 | |
2058 | By default, all watchers have a C<void *data> member. By redefining |
2252 | By default, all watchers have a C<void *data> member. By redefining |
2059 | this macro to a something else you can include more and other types of |
2253 | this macro to a something else you can include more and other types of |
… | |
… | |
2088 | interface) and F<EV.xs> (implementation) files. Only the F<EV.xs> file |
2282 | interface) and F<EV.xs> (implementation) files. Only the F<EV.xs> file |
2089 | will be compiled. It is pretty complex because it provides its own header |
2283 | will be compiled. It is pretty complex because it provides its own header |
2090 | file. |
2284 | file. |
2091 | |
2285 | |
2092 | The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file |
2286 | The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file |
2093 | that everybody includes and which overrides some autoconf choices: |
2287 | that everybody includes and which overrides some configure choices: |
2094 | |
2288 | |
|
|
2289 | #define EV_MINIMAL 1 |
2095 | #define EV_USE_POLL 0 |
2290 | #define EV_USE_POLL 0 |
2096 | #define EV_MULTIPLICITY 0 |
2291 | #define EV_MULTIPLICITY 0 |
2097 | #define EV_PERIODICS 0 |
2292 | #define EV_PERIODIC_ENABLE 0 |
|
|
2293 | #define EV_STAT_ENABLE 0 |
|
|
2294 | #define EV_FORK_ENABLE 0 |
2098 | #define EV_CONFIG_H <config.h> |
2295 | #define EV_CONFIG_H <config.h> |
|
|
2296 | #define EV_MINPRI 0 |
|
|
2297 | #define EV_MAXPRI 0 |
2099 | |
2298 | |
2100 | #include "ev++.h" |
2299 | #include "ev++.h" |
2101 | |
2300 | |
2102 | And a F<ev_cpp.C> implementation file that contains libev proper and is compiled: |
2301 | And a F<ev_cpp.C> implementation file that contains libev proper and is compiled: |
2103 | |
2302 | |
… | |
… | |
2109 | |
2308 | |
2110 | In this section the complexities of (many of) the algorithms used inside |
2309 | In this section the complexities of (many of) the algorithms used inside |
2111 | libev will be explained. For complexity discussions about backends see the |
2310 | libev will be explained. For complexity discussions about backends see the |
2112 | documentation for C<ev_default_init>. |
2311 | documentation for C<ev_default_init>. |
2113 | |
2312 | |
|
|
2313 | All of the following are about amortised time: If an array needs to be |
|
|
2314 | extended, libev needs to realloc and move the whole array, but this |
|
|
2315 | happens asymptotically never with higher number of elements, so O(1) might |
|
|
2316 | mean it might do a lengthy realloc operation in rare cases, but on average |
|
|
2317 | it is much faster and asymptotically approaches constant time. |
|
|
2318 | |
2114 | =over 4 |
2319 | =over 4 |
2115 | |
2320 | |
2116 | =item Starting and stopping timer/periodic watchers: O(log skipped_other_timers) |
2321 | =item Starting and stopping timer/periodic watchers: O(log skipped_other_timers) |
2117 | |
2322 | |
|
|
2323 | This means that, when you have a watcher that triggers in one hour and |
|
|
2324 | there are 100 watchers that would trigger before that then inserting will |
|
|
2325 | have to skip those 100 watchers. |
|
|
2326 | |
2118 | =item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers) |
2327 | =item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers) |
2119 | |
2328 | |
|
|
2329 | That means that for changing a timer costs less than removing/adding them |
|
|
2330 | as only the relative motion in the event queue has to be paid for. |
|
|
2331 | |
2120 | =item Starting io/check/prepare/idle/signal/child watchers: O(1) |
2332 | =item Starting io/check/prepare/idle/signal/child watchers: O(1) |
2121 | |
2333 | |
|
|
2334 | These just add the watcher into an array or at the head of a list. |
2122 | =item Stopping check/prepare/idle watchers: O(1) |
2335 | =item Stopping check/prepare/idle watchers: O(1) |
2123 | |
2336 | |
2124 | =item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % 16)) |
2337 | =item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE)) |
|
|
2338 | |
|
|
2339 | These watchers are stored in lists then need to be walked to find the |
|
|
2340 | correct watcher to remove. The lists are usually short (you don't usually |
|
|
2341 | have many watchers waiting for the same fd or signal). |
2125 | |
2342 | |
2126 | =item Finding the next timer per loop iteration: O(1) |
2343 | =item Finding the next timer per loop iteration: O(1) |
2127 | |
2344 | |
2128 | =item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd) |
2345 | =item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd) |
2129 | |
2346 | |
|
|
2347 | A change means an I/O watcher gets started or stopped, which requires |
|
|
2348 | libev to recalculate its status (and possibly tell the kernel). |
|
|
2349 | |
2130 | =item Activating one watcher: O(1) |
2350 | =item Activating one watcher: O(1) |
2131 | |
2351 | |
|
|
2352 | =item Priority handling: O(number_of_priorities) |
|
|
2353 | |
|
|
2354 | Priorities are implemented by allocating some space for each |
|
|
2355 | priority. When doing priority-based operations, libev usually has to |
|
|
2356 | linearly search all the priorities. |
|
|
2357 | |
2132 | =back |
2358 | =back |
2133 | |
2359 | |
2134 | |
2360 | |
2135 | =head1 AUTHOR |
2361 | =head1 AUTHOR |
2136 | |
2362 | |