… | |
… | |
82 | |
82 | |
83 | =head1 WHAT TO READ WHEN IN A HURRY |
83 | =head1 WHAT TO READ WHEN IN A HURRY |
84 | |
84 | |
85 | This manual tries to be very detailed, but unfortunately, this also makes |
85 | This manual tries to be very detailed, but unfortunately, this also makes |
86 | it very long. If you just want to know the basics of libev, I suggest |
86 | it very long. If you just want to know the basics of libev, I suggest |
87 | reading L<ANATOMY OF A WATCHER>, then the L<EXAMPLE PROGRAM> above and |
87 | reading L</ANATOMY OF A WATCHER>, then the L</EXAMPLE PROGRAM> above and |
88 | look up the missing functions in L<GLOBAL FUNCTIONS> and the C<ev_io> and |
88 | look up the missing functions in L</GLOBAL FUNCTIONS> and the C<ev_io> and |
89 | C<ev_timer> sections in L<WATCHER TYPES>. |
89 | C<ev_timer> sections in L</WATCHER TYPES>. |
90 | |
90 | |
91 | =head1 ABOUT LIBEV |
91 | =head1 ABOUT LIBEV |
92 | |
92 | |
93 | Libev is an event loop: you register interest in certain events (such as a |
93 | Libev is an event loop: you register interest in certain events (such as a |
94 | file descriptor being readable or a timeout occurring), and it will manage |
94 | file descriptor being readable or a timeout occurring), and it will manage |
… | |
… | |
247 | the current system, you would need to look at C<ev_embeddable_backends () |
247 | the current system, you would need to look at C<ev_embeddable_backends () |
248 | & ev_supported_backends ()>, likewise for recommended ones. |
248 | & ev_supported_backends ()>, likewise for recommended ones. |
249 | |
249 | |
250 | See the description of C<ev_embed> watchers for more info. |
250 | See the description of C<ev_embed> watchers for more info. |
251 | |
251 | |
252 | =item ev_set_allocator (void *(*cb)(void *ptr, long size)) |
252 | =item ev_set_allocator (void *(*cb)(void *ptr, long size) throw ()) |
253 | |
253 | |
254 | Sets the allocation function to use (the prototype is similar - the |
254 | Sets the allocation function to use (the prototype is similar - the |
255 | semantics are identical to the C<realloc> C89/SuS/POSIX function). It is |
255 | semantics are identical to the C<realloc> C89/SuS/POSIX function). It is |
256 | used to allocate and free memory (no surprises here). If it returns zero |
256 | used to allocate and free memory (no surprises here). If it returns zero |
257 | when memory needs to be allocated (C<size != 0>), the library might abort |
257 | when memory needs to be allocated (C<size != 0>), the library might abort |
… | |
… | |
283 | } |
283 | } |
284 | |
284 | |
285 | ... |
285 | ... |
286 | ev_set_allocator (persistent_realloc); |
286 | ev_set_allocator (persistent_realloc); |
287 | |
287 | |
288 | =item ev_set_syserr_cb (void (*cb)(const char *msg)) |
288 | =item ev_set_syserr_cb (void (*cb)(const char *msg) throw ()) |
289 | |
289 | |
290 | Set the callback function to call on a retryable system call error (such |
290 | Set the callback function to call on a retryable system call error (such |
291 | as failed select, poll, epoll_wait). The message is a printable string |
291 | as failed select, poll, epoll_wait). The message is a printable string |
292 | indicating the system call or subsystem causing the problem. If this |
292 | indicating the system call or subsystem causing the problem. If this |
293 | callback is set, then libev will expect it to remedy the situation, no |
293 | callback is set, then libev will expect it to remedy the situation, no |
… | |
… | |
567 | |
567 | |
568 | It scales in the same way as the epoll backend, but the interface to the |
568 | It scales in the same way as the epoll backend, but the interface to the |
569 | kernel is more efficient (which says nothing about its actual speed, of |
569 | kernel is more efficient (which says nothing about its actual speed, of |
570 | course). While stopping, setting and starting an I/O watcher does never |
570 | course). While stopping, setting and starting an I/O watcher does never |
571 | cause an extra system call as with C<EVBACKEND_EPOLL>, it still adds up to |
571 | cause an extra system call as with C<EVBACKEND_EPOLL>, it still adds up to |
572 | two event changes per incident. Support for C<fork ()> is very bad (but |
572 | two event changes per incident. Support for C<fork ()> is very bad (you |
573 | sane, unlike epoll) and it drops fds silently in similarly hard-to-detect |
573 | might have to leak fd's on fork, but it's more sane than epoll) and it |
574 | cases |
574 | drops fds silently in similarly hard-to-detect cases |
575 | |
575 | |
576 | This backend usually performs well under most conditions. |
576 | This backend usually performs well under most conditions. |
577 | |
577 | |
578 | While nominally embeddable in other event loops, this doesn't work |
578 | While nominally embeddable in other event loops, this doesn't work |
579 | everywhere, so you might need to test for this. And since it is broken |
579 | everywhere, so you might need to test for this. And since it is broken |
… | |
… | |
764 | |
764 | |
765 | This function is rarely useful, but when some event callback runs for a |
765 | This function is rarely useful, but when some event callback runs for a |
766 | very long time without entering the event loop, updating libev's idea of |
766 | very long time without entering the event loop, updating libev's idea of |
767 | the current time is a good idea. |
767 | the current time is a good idea. |
768 | |
768 | |
769 | See also L<The special problem of time updates> in the C<ev_timer> section. |
769 | See also L</The special problem of time updates> in the C<ev_timer> section. |
770 | |
770 | |
771 | =item ev_suspend (loop) |
771 | =item ev_suspend (loop) |
772 | |
772 | |
773 | =item ev_resume (loop) |
773 | =item ev_resume (loop) |
774 | |
774 | |
… | |
… | |
792 | without a previous call to C<ev_suspend>. |
792 | without a previous call to C<ev_suspend>. |
793 | |
793 | |
794 | Calling C<ev_suspend>/C<ev_resume> has the side effect of updating the |
794 | Calling C<ev_suspend>/C<ev_resume> has the side effect of updating the |
795 | event loop time (see C<ev_now_update>). |
795 | event loop time (see C<ev_now_update>). |
796 | |
796 | |
797 | =item ev_run (loop, int flags) |
797 | =item bool ev_run (loop, int flags) |
798 | |
798 | |
799 | Finally, this is it, the event handler. This function usually is called |
799 | Finally, this is it, the event handler. This function usually is called |
800 | after you have initialised all your watchers and you want to start |
800 | after you have initialised all your watchers and you want to start |
801 | handling events. It will ask the operating system for any new events, call |
801 | handling events. It will ask the operating system for any new events, call |
802 | the watcher callbacks, an then repeat the whole process indefinitely: This |
802 | the watcher callbacks, and then repeat the whole process indefinitely: This |
803 | is why event loops are called I<loops>. |
803 | is why event loops are called I<loops>. |
804 | |
804 | |
805 | If the flags argument is specified as C<0>, it will keep handling events |
805 | If the flags argument is specified as C<0>, it will keep handling events |
806 | until either no event watchers are active anymore or C<ev_break> was |
806 | until either no event watchers are active anymore or C<ev_break> was |
807 | called. |
807 | called. |
|
|
808 | |
|
|
809 | The return value is false if there are no more active watchers (which |
|
|
810 | usually means "all jobs done" or "deadlock"), and true in all other cases |
|
|
811 | (which usually means " you should call C<ev_run> again"). |
808 | |
812 | |
809 | Please note that an explicit C<ev_break> is usually better than |
813 | Please note that an explicit C<ev_break> is usually better than |
810 | relying on all watchers to be stopped when deciding when a program has |
814 | relying on all watchers to be stopped when deciding when a program has |
811 | finished (especially in interactive programs), but having a program |
815 | finished (especially in interactive programs), but having a program |
812 | that automatically loops as long as it has to and no longer by virtue |
816 | that automatically loops as long as it has to and no longer by virtue |
813 | of relying on its watchers stopping correctly, that is truly a thing of |
817 | of relying on its watchers stopping correctly, that is truly a thing of |
814 | beauty. |
818 | beauty. |
815 | |
819 | |
816 | This function is also I<mostly> exception-safe - you can break out of |
820 | This function is I<mostly> exception-safe - you can break out of a |
817 | a C<ev_run> call by calling C<longjmp> in a callback, throwing a C++ |
821 | C<ev_run> call by calling C<longjmp> in a callback, throwing a C++ |
818 | exception and so on. This does not decrement the C<ev_depth> value, nor |
822 | exception and so on. This does not decrement the C<ev_depth> value, nor |
819 | will it clear any outstanding C<EVBREAK_ONE> breaks. |
823 | will it clear any outstanding C<EVBREAK_ONE> breaks. |
820 | |
824 | |
821 | A flags value of C<EVRUN_NOWAIT> will look for new events, will handle |
825 | A flags value of C<EVRUN_NOWAIT> will look for new events, will handle |
822 | those events and any already outstanding ones, but will not wait and |
826 | those events and any already outstanding ones, but will not wait and |
… | |
… | |
1012 | invoke the actual watchers inside another context (another thread etc.). |
1016 | invoke the actual watchers inside another context (another thread etc.). |
1013 | |
1017 | |
1014 | If you want to reset the callback, use C<ev_invoke_pending> as new |
1018 | If you want to reset the callback, use C<ev_invoke_pending> as new |
1015 | callback. |
1019 | callback. |
1016 | |
1020 | |
1017 | =item ev_set_loop_release_cb (loop, void (*release)(EV_P), void (*acquire)(EV_P)) |
1021 | =item ev_set_loop_release_cb (loop, void (*release)(EV_P) throw (), void (*acquire)(EV_P) throw ()) |
1018 | |
1022 | |
1019 | Sometimes you want to share the same loop between multiple threads. This |
1023 | Sometimes you want to share the same loop between multiple threads. This |
1020 | can be done relatively simply by putting mutex_lock/unlock calls around |
1024 | can be done relatively simply by putting mutex_lock/unlock calls around |
1021 | each call to a libev function. |
1025 | each call to a libev function. |
1022 | |
1026 | |
… | |
… | |
1170 | |
1174 | |
1171 | =item C<EV_PREPARE> |
1175 | =item C<EV_PREPARE> |
1172 | |
1176 | |
1173 | =item C<EV_CHECK> |
1177 | =item C<EV_CHECK> |
1174 | |
1178 | |
1175 | All C<ev_prepare> watchers are invoked just I<before> C<ev_run> starts |
1179 | All C<ev_prepare> watchers are invoked just I<before> C<ev_run> starts to |
1176 | to gather new events, and all C<ev_check> watchers are invoked just after |
1180 | gather new events, and all C<ev_check> watchers are queued (not invoked) |
1177 | C<ev_run> has gathered them, but before it invokes any callbacks for any |
1181 | just after C<ev_run> has gathered them, but before it queues any callbacks |
|
|
1182 | for any received events. That means C<ev_prepare> watchers are the last |
|
|
1183 | watchers invoked before the event loop sleeps or polls for new events, and |
|
|
1184 | C<ev_check> watchers will be invoked before any other watchers of the same |
|
|
1185 | or lower priority within an event loop iteration. |
|
|
1186 | |
1178 | received events. Callbacks of both watcher types can start and stop as |
1187 | Callbacks of both watcher types can start and stop as many watchers as |
1179 | many watchers as they want, and all of them will be taken into account |
1188 | they want, and all of them will be taken into account (for example, a |
1180 | (for example, a C<ev_prepare> watcher might start an idle watcher to keep |
1189 | C<ev_prepare> watcher might start an idle watcher to keep C<ev_run> from |
1181 | C<ev_run> from blocking). |
1190 | blocking). |
1182 | |
1191 | |
1183 | =item C<EV_EMBED> |
1192 | =item C<EV_EMBED> |
1184 | |
1193 | |
1185 | The embedded event loop specified in the C<ev_embed> watcher needs attention. |
1194 | The embedded event loop specified in the C<ev_embed> watcher needs attention. |
1186 | |
1195 | |
… | |
… | |
1309 | |
1318 | |
1310 | =item callback ev_cb (ev_TYPE *watcher) |
1319 | =item callback ev_cb (ev_TYPE *watcher) |
1311 | |
1320 | |
1312 | Returns the callback currently set on the watcher. |
1321 | Returns the callback currently set on the watcher. |
1313 | |
1322 | |
1314 | =item ev_cb_set (ev_TYPE *watcher, callback) |
1323 | =item ev_set_cb (ev_TYPE *watcher, callback) |
1315 | |
1324 | |
1316 | Change the callback. You can change the callback at virtually any time |
1325 | Change the callback. You can change the callback at virtually any time |
1317 | (modulo threads). |
1326 | (modulo threads). |
1318 | |
1327 | |
1319 | =item ev_set_priority (ev_TYPE *watcher, int priority) |
1328 | =item ev_set_priority (ev_TYPE *watcher, int priority) |
… | |
… | |
1337 | or might not have been clamped to the valid range. |
1346 | or might not have been clamped to the valid range. |
1338 | |
1347 | |
1339 | The default priority used by watchers when no priority has been set is |
1348 | The default priority used by watchers when no priority has been set is |
1340 | always C<0>, which is supposed to not be too high and not be too low :). |
1349 | always C<0>, which is supposed to not be too high and not be too low :). |
1341 | |
1350 | |
1342 | See L<WATCHER PRIORITY MODELS>, below, for a more thorough treatment of |
1351 | See L</WATCHER PRIORITY MODELS>, below, for a more thorough treatment of |
1343 | priorities. |
1352 | priorities. |
1344 | |
1353 | |
1345 | =item ev_invoke (loop, ev_TYPE *watcher, int revents) |
1354 | =item ev_invoke (loop, ev_TYPE *watcher, int revents) |
1346 | |
1355 | |
1347 | Invoke the C<watcher> with the given C<loop> and C<revents>. Neither |
1356 | Invoke the C<watcher> with the given C<loop> and C<revents>. Neither |
… | |
… | |
1372 | See also C<ev_feed_fd_event> and C<ev_feed_signal_event> for related |
1381 | See also C<ev_feed_fd_event> and C<ev_feed_signal_event> for related |
1373 | functions that do not need a watcher. |
1382 | functions that do not need a watcher. |
1374 | |
1383 | |
1375 | =back |
1384 | =back |
1376 | |
1385 | |
1377 | See also the L<ASSOCIATING CUSTOM DATA WITH A WATCHER> and L<BUILDING YOUR |
1386 | See also the L</ASSOCIATING CUSTOM DATA WITH A WATCHER> and L</BUILDING YOUR |
1378 | OWN COMPOSITE WATCHERS> idioms. |
1387 | OWN COMPOSITE WATCHERS> idioms. |
1379 | |
1388 | |
1380 | =head2 WATCHER STATES |
1389 | =head2 WATCHER STATES |
1381 | |
1390 | |
1382 | There are various watcher states mentioned throughout this manual - |
1391 | There are various watcher states mentioned throughout this manual - |
… | |
… | |
1870 | callback (EV_P_ ev_timer *w, int revents) |
1879 | callback (EV_P_ ev_timer *w, int revents) |
1871 | { |
1880 | { |
1872 | // calculate when the timeout would happen |
1881 | // calculate when the timeout would happen |
1873 | ev_tstamp after = last_activity - ev_now (EV_A) + timeout; |
1882 | ev_tstamp after = last_activity - ev_now (EV_A) + timeout; |
1874 | |
1883 | |
1875 | // if negative, it means we the timeout already occured |
1884 | // if negative, it means we the timeout already occurred |
1876 | if (after < 0.) |
1885 | if (after < 0.) |
1877 | { |
1886 | { |
1878 | // timeout occurred, take action |
1887 | // timeout occurred, take action |
1879 | } |
1888 | } |
1880 | else |
1889 | else |
… | |
… | |
1898 | |
1907 | |
1899 | Otherwise, we now the earliest time at which the timeout would trigger, |
1908 | Otherwise, we now the earliest time at which the timeout would trigger, |
1900 | and simply start the timer with this timeout value. |
1909 | and simply start the timer with this timeout value. |
1901 | |
1910 | |
1902 | In other words, each time the callback is invoked it will check whether |
1911 | In other words, each time the callback is invoked it will check whether |
1903 | the timeout cocured. If not, it will simply reschedule itself to check |
1912 | the timeout occurred. If not, it will simply reschedule itself to check |
1904 | again at the earliest time it could time out. Rinse. Repeat. |
1913 | again at the earliest time it could time out. Rinse. Repeat. |
1905 | |
1914 | |
1906 | This scheme causes more callback invocations (about one every 60 seconds |
1915 | This scheme causes more callback invocations (about one every 60 seconds |
1907 | minus half the average time between activity), but virtually no calls to |
1916 | minus half the average time between activity), but virtually no calls to |
1908 | libev to change the timeout. |
1917 | libev to change the timeout. |
… | |
… | |
1922 | if (activity detected) |
1931 | if (activity detected) |
1923 | last_activity = ev_now (EV_A); |
1932 | last_activity = ev_now (EV_A); |
1924 | |
1933 | |
1925 | When your timeout value changes, then the timeout can be changed by simply |
1934 | When your timeout value changes, then the timeout can be changed by simply |
1926 | providing a new value, stopping the timer and calling the callback, which |
1935 | providing a new value, stopping the timer and calling the callback, which |
1927 | will agaion do the right thing (for example, time out immediately :). |
1936 | will again do the right thing (for example, time out immediately :). |
1928 | |
1937 | |
1929 | timeout = new_value; |
1938 | timeout = new_value; |
1930 | ev_timer_stop (EV_A_ &timer); |
1939 | ev_timer_stop (EV_A_ &timer); |
1931 | callback (EV_A_ &timer, 0); |
1940 | callback (EV_A_ &timer, 0); |
1932 | |
1941 | |
… | |
… | |
2127 | =item If the timer is repeating, make the C<repeat> value the new timeout |
2136 | =item If the timer is repeating, make the C<repeat> value the new timeout |
2128 | and start the timer, if necessary. |
2137 | and start the timer, if necessary. |
2129 | |
2138 | |
2130 | =back |
2139 | =back |
2131 | |
2140 | |
2132 | This sounds a bit complicated, see L<Be smart about timeouts>, above, for a |
2141 | This sounds a bit complicated, see L</Be smart about timeouts>, above, for a |
2133 | usage example. |
2142 | usage example. |
2134 | |
2143 | |
2135 | =item ev_tstamp ev_timer_remaining (loop, ev_timer *) |
2144 | =item ev_tstamp ev_timer_remaining (loop, ev_timer *) |
2136 | |
2145 | |
2137 | Returns the remaining time until a timer fires. If the timer is active, |
2146 | Returns the remaining time until a timer fires. If the timer is active, |
… | |
… | |
2838 | Apart from keeping your process non-blocking (which is a useful |
2847 | Apart from keeping your process non-blocking (which is a useful |
2839 | effect on its own sometimes), idle watchers are a good place to do |
2848 | effect on its own sometimes), idle watchers are a good place to do |
2840 | "pseudo-background processing", or delay processing stuff to after the |
2849 | "pseudo-background processing", or delay processing stuff to after the |
2841 | event loop has handled all outstanding events. |
2850 | event loop has handled all outstanding events. |
2842 | |
2851 | |
|
|
2852 | =head3 Abusing an C<ev_idle> watcher for its side-effect |
|
|
2853 | |
|
|
2854 | As long as there is at least one active idle watcher, libev will never |
|
|
2855 | sleep unnecessarily. Or in other words, it will loop as fast as possible. |
|
|
2856 | For this to work, the idle watcher doesn't need to be invoked at all - the |
|
|
2857 | lowest priority will do. |
|
|
2858 | |
|
|
2859 | This mode of operation can be useful together with an C<ev_check> watcher, |
|
|
2860 | to do something on each event loop iteration - for example to balance load |
|
|
2861 | between different connections. |
|
|
2862 | |
|
|
2863 | See L</Abusing an C<ev_check> watcher for its side-effect> for a longer |
|
|
2864 | example. |
|
|
2865 | |
2843 | =head3 Watcher-Specific Functions and Data Members |
2866 | =head3 Watcher-Specific Functions and Data Members |
2844 | |
2867 | |
2845 | =over 4 |
2868 | =over 4 |
2846 | |
2869 | |
2847 | =item ev_idle_init (ev_idle *, callback) |
2870 | =item ev_idle_init (ev_idle *, callback) |
… | |
… | |
2858 | callback, free it. Also, use no error checking, as usual. |
2881 | callback, free it. Also, use no error checking, as usual. |
2859 | |
2882 | |
2860 | static void |
2883 | static void |
2861 | idle_cb (struct ev_loop *loop, ev_idle *w, int revents) |
2884 | idle_cb (struct ev_loop *loop, ev_idle *w, int revents) |
2862 | { |
2885 | { |
|
|
2886 | // stop the watcher |
|
|
2887 | ev_idle_stop (loop, w); |
|
|
2888 | |
|
|
2889 | // now we can free it |
2863 | free (w); |
2890 | free (w); |
|
|
2891 | |
2864 | // now do something you wanted to do when the program has |
2892 | // now do something you wanted to do when the program has |
2865 | // no longer anything immediate to do. |
2893 | // no longer anything immediate to do. |
2866 | } |
2894 | } |
2867 | |
2895 | |
2868 | ev_idle *idle_watcher = malloc (sizeof (ev_idle)); |
2896 | ev_idle *idle_watcher = malloc (sizeof (ev_idle)); |
… | |
… | |
2870 | ev_idle_start (loop, idle_watcher); |
2898 | ev_idle_start (loop, idle_watcher); |
2871 | |
2899 | |
2872 | |
2900 | |
2873 | =head2 C<ev_prepare> and C<ev_check> - customise your event loop! |
2901 | =head2 C<ev_prepare> and C<ev_check> - customise your event loop! |
2874 | |
2902 | |
2875 | Prepare and check watchers are usually (but not always) used in pairs: |
2903 | Prepare and check watchers are often (but not always) used in pairs: |
2876 | prepare watchers get invoked before the process blocks and check watchers |
2904 | prepare watchers get invoked before the process blocks and check watchers |
2877 | afterwards. |
2905 | afterwards. |
2878 | |
2906 | |
2879 | You I<must not> call C<ev_run> or similar functions that enter |
2907 | You I<must not> call C<ev_run> or similar functions that enter |
2880 | the current event loop from either C<ev_prepare> or C<ev_check> |
2908 | the current event loop from either C<ev_prepare> or C<ev_check> |
… | |
… | |
2908 | with priority higher than or equal to the event loop and one coroutine |
2936 | with priority higher than or equal to the event loop and one coroutine |
2909 | of lower priority, but only once, using idle watchers to keep the event |
2937 | of lower priority, but only once, using idle watchers to keep the event |
2910 | loop from blocking if lower-priority coroutines are active, thus mapping |
2938 | loop from blocking if lower-priority coroutines are active, thus mapping |
2911 | low-priority coroutines to idle/background tasks). |
2939 | low-priority coroutines to idle/background tasks). |
2912 | |
2940 | |
2913 | It is recommended to give C<ev_check> watchers highest (C<EV_MAXPRI>) |
2941 | When used for this purpose, it is recommended to give C<ev_check> watchers |
2914 | priority, to ensure that they are being run before any other watchers |
2942 | highest (C<EV_MAXPRI>) priority, to ensure that they are being run before |
2915 | after the poll (this doesn't matter for C<ev_prepare> watchers). |
2943 | any other watchers after the poll (this doesn't matter for C<ev_prepare> |
|
|
2944 | watchers). |
2916 | |
2945 | |
2917 | Also, C<ev_check> watchers (and C<ev_prepare> watchers, too) should not |
2946 | Also, C<ev_check> watchers (and C<ev_prepare> watchers, too) should not |
2918 | activate ("feed") events into libev. While libev fully supports this, they |
2947 | activate ("feed") events into libev. While libev fully supports this, they |
2919 | might get executed before other C<ev_check> watchers did their job. As |
2948 | might get executed before other C<ev_check> watchers did their job. As |
2920 | C<ev_check> watchers are often used to embed other (non-libev) event |
2949 | C<ev_check> watchers are often used to embed other (non-libev) event |
2921 | loops those other event loops might be in an unusable state until their |
2950 | loops those other event loops might be in an unusable state until their |
2922 | C<ev_check> watcher ran (always remind yourself to coexist peacefully with |
2951 | C<ev_check> watcher ran (always remind yourself to coexist peacefully with |
2923 | others). |
2952 | others). |
|
|
2953 | |
|
|
2954 | =head3 Abusing an C<ev_check> watcher for its side-effect |
|
|
2955 | |
|
|
2956 | C<ev_check> (and less often also C<ev_prepare>) watchers can also be |
|
|
2957 | useful because they are called once per event loop iteration. For |
|
|
2958 | example, if you want to handle a large number of connections fairly, you |
|
|
2959 | normally only do a bit of work for each active connection, and if there |
|
|
2960 | is more work to do, you wait for the next event loop iteration, so other |
|
|
2961 | connections have a chance of making progress. |
|
|
2962 | |
|
|
2963 | Using an C<ev_check> watcher is almost enough: it will be called on the |
|
|
2964 | next event loop iteration. However, that isn't as soon as possible - |
|
|
2965 | without external events, your C<ev_check> watcher will not be invoked. |
|
|
2966 | |
|
|
2967 | |
|
|
2968 | This is where C<ev_idle> watchers come in handy - all you need is a |
|
|
2969 | single global idle watcher that is active as long as you have one active |
|
|
2970 | C<ev_check> watcher. The C<ev_idle> watcher makes sure the event loop |
|
|
2971 | will not sleep, and the C<ev_check> watcher makes sure a callback gets |
|
|
2972 | invoked. Neither watcher alone can do that. |
2924 | |
2973 | |
2925 | =head3 Watcher-Specific Functions and Data Members |
2974 | =head3 Watcher-Specific Functions and Data Members |
2926 | |
2975 | |
2927 | =over 4 |
2976 | =over 4 |
2928 | |
2977 | |
… | |
… | |
3309 | it by calling C<ev_async_send>, which is thread- and signal safe. |
3358 | it by calling C<ev_async_send>, which is thread- and signal safe. |
3310 | |
3359 | |
3311 | This functionality is very similar to C<ev_signal> watchers, as signals, |
3360 | This functionality is very similar to C<ev_signal> watchers, as signals, |
3312 | too, are asynchronous in nature, and signals, too, will be compressed |
3361 | too, are asynchronous in nature, and signals, too, will be compressed |
3313 | (i.e. the number of callback invocations may be less than the number of |
3362 | (i.e. the number of callback invocations may be less than the number of |
3314 | C<ev_async_sent> calls). In fact, you could use signal watchers as a kind |
3363 | C<ev_async_send> calls). In fact, you could use signal watchers as a kind |
3315 | of "global async watchers" by using a watcher on an otherwise unused |
3364 | of "global async watchers" by using a watcher on an otherwise unused |
3316 | signal, and C<ev_feed_signal> to signal this watcher from another thread, |
3365 | signal, and C<ev_feed_signal> to signal this watcher from another thread, |
3317 | even without knowing which loop owns the signal. |
3366 | even without knowing which loop owns the signal. |
3318 | |
3367 | |
3319 | =head3 Queueing |
3368 | =head3 Queueing |
… | |
… | |
3826 | called): |
3875 | called): |
3827 | |
3876 | |
3828 | void |
3877 | void |
3829 | wait_for_event (ev_watcher *w) |
3878 | wait_for_event (ev_watcher *w) |
3830 | { |
3879 | { |
3831 | ev_cb_set (w) = current_coro; |
3880 | ev_set_cb (w, current_coro); |
3832 | switch_to (libev_coro); |
3881 | switch_to (libev_coro); |
3833 | } |
3882 | } |
3834 | |
3883 | |
3835 | That basically suspends the coroutine inside C<wait_for_event> and |
3884 | That basically suspends the coroutine inside C<wait_for_event> and |
3836 | continues the libev coroutine, which, when appropriate, switches back to |
3885 | continues the libev coroutine, which, when appropriate, switches back to |
… | |
… | |
3839 | You can do similar tricks if you have, say, threads with an event queue - |
3888 | You can do similar tricks if you have, say, threads with an event queue - |
3840 | instead of storing a coroutine, you store the queue object and instead of |
3889 | instead of storing a coroutine, you store the queue object and instead of |
3841 | switching to a coroutine, you push the watcher onto the queue and notify |
3890 | switching to a coroutine, you push the watcher onto the queue and notify |
3842 | any waiters. |
3891 | any waiters. |
3843 | |
3892 | |
3844 | To embed libev, see L<EMBEDDING>, but in short, it's easiest to create two |
3893 | To embed libev, see L</EMBEDDING>, but in short, it's easiest to create two |
3845 | files, F<my_ev.h> and F<my_ev.c> that include the respective libev files: |
3894 | files, F<my_ev.h> and F<my_ev.c> that include the respective libev files: |
3846 | |
3895 | |
3847 | // my_ev.h |
3896 | // my_ev.h |
3848 | #define EV_CB_DECLARE(type) struct my_coro *cb; |
3897 | #define EV_CB_DECLARE(type) struct my_coro *cb; |
3849 | #define EV_CB_INVOKE(watcher) switch_to ((watcher)->cb); |
3898 | #define EV_CB_INVOKE(watcher) switch_to ((watcher)->cb); |
… | |
… | |
3892 | to use the libev header file and library. |
3941 | to use the libev header file and library. |
3893 | |
3942 | |
3894 | =back |
3943 | =back |
3895 | |
3944 | |
3896 | =head1 C++ SUPPORT |
3945 | =head1 C++ SUPPORT |
|
|
3946 | |
|
|
3947 | =head2 C API |
|
|
3948 | |
|
|
3949 | The normal C API should work fine when used from C++: both ev.h and the |
|
|
3950 | libev sources can be compiled as C++. Therefore, code that uses the C API |
|
|
3951 | will work fine. |
|
|
3952 | |
|
|
3953 | Proper exception specifications might have to be added to callbacks passed |
|
|
3954 | to libev: exceptions may be thrown only from watcher callbacks, all |
|
|
3955 | other callbacks (allocator, syserr, loop acquire/release and periodioc |
|
|
3956 | reschedule callbacks) must not throw exceptions, and might need a C<throw |
|
|
3957 | ()> specification. If you have code that needs to be compiled as both C |
|
|
3958 | and C++ you can use the C<EV_THROW> macro for this: |
|
|
3959 | |
|
|
3960 | static void |
|
|
3961 | fatal_error (const char *msg) EV_THROW |
|
|
3962 | { |
|
|
3963 | perror (msg); |
|
|
3964 | abort (); |
|
|
3965 | } |
|
|
3966 | |
|
|
3967 | ... |
|
|
3968 | ev_set_syserr_cb (fatal_error); |
|
|
3969 | |
|
|
3970 | The only API functions that can currently throw exceptions are C<ev_run>, |
|
|
3971 | C<ev_invoke>, C<ev_invoke_pending> and C<ev_loop_destroy> (the latter |
|
|
3972 | because it runs cleanup watchers). |
|
|
3973 | |
|
|
3974 | Throwing exceptions in watcher callbacks is only supported if libev itself |
|
|
3975 | is compiled with a C++ compiler or your C and C++ environments allow |
|
|
3976 | throwing exceptions through C libraries (most do). |
|
|
3977 | |
|
|
3978 | =head2 C++ API |
3897 | |
3979 | |
3898 | Libev comes with some simplistic wrapper classes for C++ that mainly allow |
3980 | Libev comes with some simplistic wrapper classes for C++ that mainly allow |
3899 | you to use some convenience methods to start/stop watchers and also change |
3981 | you to use some convenience methods to start/stop watchers and also change |
3900 | the callback model to a model using method callbacks on objects. |
3982 | the callback model to a model using method callbacks on objects. |
3901 | |
3983 | |
… | |
… | |
3916 | Currently, functions, static and non-static member functions and classes |
3998 | Currently, functions, static and non-static member functions and classes |
3917 | with C<operator ()> can be used as callbacks. Other types should be easy |
3999 | with C<operator ()> can be used as callbacks. Other types should be easy |
3918 | to add as long as they only need one additional pointer for context. If |
4000 | to add as long as they only need one additional pointer for context. If |
3919 | you need support for other types of functors please contact the author |
4001 | you need support for other types of functors please contact the author |
3920 | (preferably after implementing it). |
4002 | (preferably after implementing it). |
|
|
4003 | |
|
|
4004 | For all this to work, your C++ compiler either has to use the same calling |
|
|
4005 | conventions as your C compiler (for static member functions), or you have |
|
|
4006 | to embed libev and compile libev itself as C++. |
3921 | |
4007 | |
3922 | Here is a list of things available in the C<ev> namespace: |
4008 | Here is a list of things available in the C<ev> namespace: |
3923 | |
4009 | |
3924 | =over 4 |
4010 | =over 4 |
3925 | |
4011 | |
… | |
… | |
4612 | #define EV_USE_POLL 1 |
4698 | #define EV_USE_POLL 1 |
4613 | #define EV_CHILD_ENABLE 1 |
4699 | #define EV_CHILD_ENABLE 1 |
4614 | #define EV_ASYNC_ENABLE 1 |
4700 | #define EV_ASYNC_ENABLE 1 |
4615 | |
4701 | |
4616 | The actual value is a bitset, it can be a combination of the following |
4702 | The actual value is a bitset, it can be a combination of the following |
4617 | values: |
4703 | values (by default, all of these are enabled): |
4618 | |
4704 | |
4619 | =over 4 |
4705 | =over 4 |
4620 | |
4706 | |
4621 | =item C<1> - faster/larger code |
4707 | =item C<1> - faster/larger code |
4622 | |
4708 | |
… | |
… | |
4626 | code size by roughly 30% on amd64). |
4712 | code size by roughly 30% on amd64). |
4627 | |
4713 | |
4628 | When optimising for size, use of compiler flags such as C<-Os> with |
4714 | When optimising for size, use of compiler flags such as C<-Os> with |
4629 | gcc is recommended, as well as C<-DNDEBUG>, as libev contains a number of |
4715 | gcc is recommended, as well as C<-DNDEBUG>, as libev contains a number of |
4630 | assertions. |
4716 | assertions. |
|
|
4717 | |
|
|
4718 | The default is off when C<__OPTIMIZE_SIZE__> is defined by your compiler |
|
|
4719 | (e.g. gcc with C<-Os>). |
4631 | |
4720 | |
4632 | =item C<2> - faster/larger data structures |
4721 | =item C<2> - faster/larger data structures |
4633 | |
4722 | |
4634 | Replaces the small 2-heap for timer management by a faster 4-heap, larger |
4723 | Replaces the small 2-heap for timer management by a faster 4-heap, larger |
4635 | hash table sizes and so on. This will usually further increase code size |
4724 | hash table sizes and so on. This will usually further increase code size |
4636 | and can additionally have an effect on the size of data structures at |
4725 | and can additionally have an effect on the size of data structures at |
4637 | runtime. |
4726 | runtime. |
|
|
4727 | |
|
|
4728 | The default is off when C<__OPTIMIZE_SIZE__> is defined by your compiler |
|
|
4729 | (e.g. gcc with C<-Os>). |
4638 | |
4730 | |
4639 | =item C<4> - full API configuration |
4731 | =item C<4> - full API configuration |
4640 | |
4732 | |
4641 | This enables priorities (sets C<EV_MAXPRI>=2 and C<EV_MINPRI>=-2), and |
4733 | This enables priorities (sets C<EV_MAXPRI>=2 and C<EV_MINPRI>=-2), and |
4642 | enables multiplicity (C<EV_MULTIPLICITY>=1). |
4734 | enables multiplicity (C<EV_MULTIPLICITY>=1). |
… | |
… | |
4901 | default loop and triggering an C<ev_async> watcher from the default loop |
4993 | default loop and triggering an C<ev_async> watcher from the default loop |
4902 | watcher callback into the event loop interested in the signal. |
4994 | watcher callback into the event loop interested in the signal. |
4903 | |
4995 | |
4904 | =back |
4996 | =back |
4905 | |
4997 | |
4906 | See also L<THREAD LOCKING EXAMPLE>. |
4998 | See also L</THREAD LOCKING EXAMPLE>. |
4907 | |
4999 | |
4908 | =head3 COROUTINES |
5000 | =head3 COROUTINES |
4909 | |
5001 | |
4910 | Libev is very accommodating to coroutines ("cooperative threads"): |
5002 | Libev is very accommodating to coroutines ("cooperative threads"): |
4911 | libev fully supports nesting calls to its functions from different |
5003 | libev fully supports nesting calls to its functions from different |
… | |
… | |
5317 | =over 4 |
5409 | =over 4 |
5318 | |
5410 | |
5319 | =item C<EV_COMPAT3> backwards compatibility mechanism |
5411 | =item C<EV_COMPAT3> backwards compatibility mechanism |
5320 | |
5412 | |
5321 | The backward compatibility mechanism can be controlled by |
5413 | The backward compatibility mechanism can be controlled by |
5322 | C<EV_COMPAT3>. See L<PREPROCESSOR SYMBOLS/MACROS> in the L<EMBEDDING> |
5414 | C<EV_COMPAT3>. See L</PREPROCESSOR SYMBOLS/MACROS> in the L</EMBEDDING> |
5323 | section. |
5415 | section. |
5324 | |
5416 | |
5325 | =item C<ev_default_destroy> and C<ev_default_fork> have been removed |
5417 | =item C<ev_default_destroy> and C<ev_default_fork> have been removed |
5326 | |
5418 | |
5327 | These calls can be replaced easily by their C<ev_loop_xxx> counterparts: |
5419 | These calls can be replaced easily by their C<ev_loop_xxx> counterparts: |
… | |
… | |
5370 | =over 4 |
5462 | =over 4 |
5371 | |
5463 | |
5372 | =item active |
5464 | =item active |
5373 | |
5465 | |
5374 | A watcher is active as long as it has been started and not yet stopped. |
5466 | A watcher is active as long as it has been started and not yet stopped. |
5375 | See L<WATCHER STATES> for details. |
5467 | See L</WATCHER STATES> for details. |
5376 | |
5468 | |
5377 | =item application |
5469 | =item application |
5378 | |
5470 | |
5379 | In this document, an application is whatever is using libev. |
5471 | In this document, an application is whatever is using libev. |
5380 | |
5472 | |
… | |
… | |
5416 | watchers and events. |
5508 | watchers and events. |
5417 | |
5509 | |
5418 | =item pending |
5510 | =item pending |
5419 | |
5511 | |
5420 | A watcher is pending as soon as the corresponding event has been |
5512 | A watcher is pending as soon as the corresponding event has been |
5421 | detected. See L<WATCHER STATES> for details. |
5513 | detected. See L</WATCHER STATES> for details. |
5422 | |
5514 | |
5423 | =item real time |
5515 | =item real time |
5424 | |
5516 | |
5425 | The physical time that is observed. It is apparently strictly monotonic :) |
5517 | The physical time that is observed. It is apparently strictly monotonic :) |
5426 | |
5518 | |