… | |
… | |
98 | =head2 FEATURES |
98 | =head2 FEATURES |
99 | |
99 | |
100 | Libev supports C<select>, C<poll>, the Linux-specific C<epoll>, the |
100 | Libev supports C<select>, C<poll>, the Linux-specific C<epoll>, the |
101 | BSD-specific C<kqueue> and the Solaris-specific event port mechanisms |
101 | BSD-specific C<kqueue> and the Solaris-specific event port mechanisms |
102 | for file descriptor events (C<ev_io>), the Linux C<inotify> interface |
102 | for file descriptor events (C<ev_io>), the Linux C<inotify> interface |
103 | (for C<ev_stat>), relative timers (C<ev_timer>), absolute timers |
103 | (for C<ev_stat>), Linux eventfd/signalfd (for faster and cleaner |
104 | with customised rescheduling (C<ev_periodic>), synchronous signals |
104 | inter-thread wakeup (C<ev_async>)/signal handling (C<ev_signal>)) relative |
105 | (C<ev_signal>), process status change events (C<ev_child>), and event |
105 | timers (C<ev_timer>), absolute timers with customised rescheduling |
106 | watchers dealing with the event loop mechanism itself (C<ev_idle>, |
106 | (C<ev_periodic>), synchronous signals (C<ev_signal>), process status |
107 | C<ev_embed>, C<ev_prepare> and C<ev_check> watchers) as well as |
107 | change events (C<ev_child>), and event watchers dealing with the event |
108 | file watchers (C<ev_stat>) and even limited support for fork events |
108 | loop mechanism itself (C<ev_idle>, C<ev_embed>, C<ev_prepare> and |
109 | (C<ev_fork>). |
109 | C<ev_check> watchers) as well as file watchers (C<ev_stat>) and even |
|
|
110 | limited support for fork events (C<ev_fork>). |
110 | |
111 | |
111 | It also is quite fast (see this |
112 | It also is quite fast (see this |
112 | L<benchmark|http://libev.schmorp.de/bench.html> comparing it to libevent |
113 | L<benchmark|http://libev.schmorp.de/bench.html> comparing it to libevent |
113 | for example). |
114 | for example). |
114 | |
115 | |
… | |
… | |
117 | Libev is very configurable. In this manual the default (and most common) |
118 | Libev is very configurable. In this manual the default (and most common) |
118 | configuration will be described, which supports multiple event loops. For |
119 | configuration will be described, which supports multiple event loops. For |
119 | more info about various configuration options please have a look at |
120 | more info about various configuration options please have a look at |
120 | B<EMBED> section in this manual. If libev was configured without support |
121 | B<EMBED> section in this manual. If libev was configured without support |
121 | for multiple event loops, then all functions taking an initial argument of |
122 | for multiple event loops, then all functions taking an initial argument of |
122 | name C<loop> (which is always of type C<ev_loop *>) will not have |
123 | name C<loop> (which is always of type C<struct ev_loop *>) will not have |
123 | this argument. |
124 | this argument. |
124 | |
125 | |
125 | =head2 TIME REPRESENTATION |
126 | =head2 TIME REPRESENTATION |
126 | |
127 | |
127 | Libev represents time as a single floating point number, representing |
128 | Libev represents time as a single floating point number, representing |
… | |
… | |
362 | flag. |
363 | flag. |
363 | |
364 | |
364 | This flag setting cannot be overridden or specified in the C<LIBEV_FLAGS> |
365 | This flag setting cannot be overridden or specified in the C<LIBEV_FLAGS> |
365 | environment variable. |
366 | environment variable. |
366 | |
367 | |
|
|
368 | =item C<EVFLAG_NOINOTIFY> |
|
|
369 | |
|
|
370 | When this flag is specified, then libev will not attempt to use the |
|
|
371 | I<inotify> API for it's C<ev_stat> watchers. Apart from debugging and |
|
|
372 | testing, this flag can be useful to conserve inotify file descriptors, as |
|
|
373 | otherwise each loop using C<ev_stat> watchers consumes one inotify handle. |
|
|
374 | |
|
|
375 | =item C<EVFLAG_SIGNALFD> |
|
|
376 | |
|
|
377 | When this flag is specified, then libev will attempt to use the |
|
|
378 | I<signalfd> API for it's C<ev_signal> (and C<ev_child>) watchers. This API |
|
|
379 | delivers signals synchronously, which makes it both faster and might make |
|
|
380 | it possible to get the queued signal data. It can also simplify signal |
|
|
381 | handling with threads, as long as you properly block signals in your |
|
|
382 | threads that are not interested in handling them. |
|
|
383 | |
|
|
384 | Signalfd will not be used by default as this changes your signal mask, and |
|
|
385 | there are a lot of shoddy libraries and programs (glib's threadpool for |
|
|
386 | example) that can't properly initialise their signal masks. |
|
|
387 | |
367 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
388 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
368 | |
389 | |
369 | This is your standard select(2) backend. Not I<completely> standard, as |
390 | This is your standard select(2) backend. Not I<completely> standard, as |
370 | libev tries to roll its own fd_set with no limits on the number of fds, |
391 | libev tries to roll its own fd_set with no limits on the number of fds, |
371 | but if that fails, expect a fairly low limit on the number of fds when |
392 | but if that fails, expect a fairly low limit on the number of fds when |
… | |
… | |
394 | |
415 | |
395 | This backend maps C<EV_READ> to C<POLLIN | POLLERR | POLLHUP>, and |
416 | This backend maps C<EV_READ> to C<POLLIN | POLLERR | POLLHUP>, and |
396 | C<EV_WRITE> to C<POLLOUT | POLLERR | POLLHUP>. |
417 | C<EV_WRITE> to C<POLLOUT | POLLERR | POLLHUP>. |
397 | |
418 | |
398 | =item C<EVBACKEND_EPOLL> (value 4, Linux) |
419 | =item C<EVBACKEND_EPOLL> (value 4, Linux) |
|
|
420 | |
|
|
421 | Use the linux-specific epoll(7) interface (for both pre- and post-2.6.9 |
|
|
422 | kernels). |
399 | |
423 | |
400 | For few fds, this backend is a bit little slower than poll and select, |
424 | For few fds, this backend is a bit little slower than poll and select, |
401 | but it scales phenomenally better. While poll and select usually scale |
425 | but it scales phenomenally better. While poll and select usually scale |
402 | like O(total_fds) where n is the total number of fds (or the highest fd), |
426 | like O(total_fds) where n is the total number of fds (or the highest fd), |
403 | epoll scales either O(1) or O(active_fds). |
427 | epoll scales either O(1) or O(active_fds). |
… | |
… | |
518 | |
542 | |
519 | It is definitely not recommended to use this flag. |
543 | It is definitely not recommended to use this flag. |
520 | |
544 | |
521 | =back |
545 | =back |
522 | |
546 | |
523 | If one or more of these are or'ed into the flags value, then only these |
547 | If one or more of the backend flags are or'ed into the flags value, |
524 | backends will be tried (in the reverse order as listed here). If none are |
548 | then only these backends will be tried (in the reverse order as listed |
525 | specified, all backends in C<ev_recommended_backends ()> will be tried. |
549 | here). If none are specified, all backends in C<ev_recommended_backends |
|
|
550 | ()> will be tried. |
526 | |
551 | |
527 | Example: This is the most typical usage. |
552 | Example: This is the most typical usage. |
528 | |
553 | |
529 | if (!ev_default_loop (0)) |
554 | if (!ev_default_loop (0)) |
530 | fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?"); |
555 | fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?"); |
… | |
… | |
573 | as signal and child watchers) would need to be stopped manually. |
598 | as signal and child watchers) would need to be stopped manually. |
574 | |
599 | |
575 | In general it is not advisable to call this function except in the |
600 | In general it is not advisable to call this function except in the |
576 | rare occasion where you really need to free e.g. the signal handling |
601 | rare occasion where you really need to free e.g. the signal handling |
577 | pipe fds. If you need dynamically allocated loops it is better to use |
602 | pipe fds. If you need dynamically allocated loops it is better to use |
578 | C<ev_loop_new> and C<ev_loop_destroy>). |
603 | C<ev_loop_new> and C<ev_loop_destroy>. |
579 | |
604 | |
580 | =item ev_loop_destroy (loop) |
605 | =item ev_loop_destroy (loop) |
581 | |
606 | |
582 | Like C<ev_default_destroy>, but destroys an event loop created by an |
607 | Like C<ev_default_destroy>, but destroys an event loop created by an |
583 | earlier call to C<ev_loop_new>. |
608 | earlier call to C<ev_loop_new>. |
… | |
… | |
687 | event loop time (see C<ev_now_update>). |
712 | event loop time (see C<ev_now_update>). |
688 | |
713 | |
689 | =item ev_loop (loop, int flags) |
714 | =item ev_loop (loop, int flags) |
690 | |
715 | |
691 | Finally, this is it, the event handler. This function usually is called |
716 | Finally, this is it, the event handler. This function usually is called |
692 | after you initialised all your watchers and you want to start handling |
717 | after you have initialised all your watchers and you want to start |
693 | events. |
718 | handling events. |
694 | |
719 | |
695 | If the flags argument is specified as C<0>, it will not return until |
720 | If the flags argument is specified as C<0>, it will not return until |
696 | either no event watchers are active anymore or C<ev_unloop> was called. |
721 | either no event watchers are active anymore or C<ev_unloop> was called. |
697 | |
722 | |
698 | Please note that an explicit C<ev_unloop> is usually better than |
723 | Please note that an explicit C<ev_unloop> is usually better than |
… | |
… | |
772 | |
797 | |
773 | Ref/unref can be used to add or remove a reference count on the event |
798 | Ref/unref can be used to add or remove a reference count on the event |
774 | loop: Every watcher keeps one reference, and as long as the reference |
799 | loop: Every watcher keeps one reference, and as long as the reference |
775 | count is nonzero, C<ev_loop> will not return on its own. |
800 | count is nonzero, C<ev_loop> will not return on its own. |
776 | |
801 | |
777 | If you have a watcher you never unregister that should not keep C<ev_loop> |
802 | This is useful when you have a watcher that you never intend to |
778 | from returning, call ev_unref() after starting, and ev_ref() before |
803 | unregister, but that nevertheless should not keep C<ev_loop> from |
|
|
804 | returning. In such a case, call C<ev_unref> after starting, and C<ev_ref> |
779 | stopping it. |
805 | before stopping it. |
780 | |
806 | |
781 | As an example, libev itself uses this for its internal signal pipe: It |
807 | As an example, libev itself uses this for its internal signal pipe: It |
782 | is not visible to the libev user and should not keep C<ev_loop> from |
808 | is not visible to the libev user and should not keep C<ev_loop> from |
783 | exiting if no event watchers registered by it are active. It is also an |
809 | exiting if no event watchers registered by it are active. It is also an |
784 | excellent way to do this for generic recurring timers or from within |
810 | excellent way to do this for generic recurring timers or from within |
… | |
… | |
862 | |
888 | |
863 | This call will simply invoke all pending watchers while resetting their |
889 | This call will simply invoke all pending watchers while resetting their |
864 | pending state. Normally, C<ev_loop> does this automatically when required, |
890 | pending state. Normally, C<ev_loop> does this automatically when required, |
865 | but when overriding the invoke callback this call comes handy. |
891 | but when overriding the invoke callback this call comes handy. |
866 | |
892 | |
|
|
893 | =item int ev_pending_count (loop) |
|
|
894 | |
|
|
895 | Returns the number of pending watchers - zero indicates that no watchers |
|
|
896 | are pending. |
|
|
897 | |
867 | =item ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(EV_P)) |
898 | =item ev_set_invoke_pending_cb (loop, void (*invoke_pending_cb)(EV_P)) |
868 | |
899 | |
869 | This overrides the invoke pending functionality of the loop: Instead of |
900 | This overrides the invoke pending functionality of the loop: Instead of |
870 | invoking all pending watchers when there are any, C<ev_loop> will call |
901 | invoking all pending watchers when there are any, C<ev_loop> will call |
871 | this callback instead. This is useful, for example, when you want to |
902 | this callback instead. This is useful, for example, when you want to |
… | |
… | |
894 | |
925 | |
895 | While event loop modifications are allowed between invocations of |
926 | While event loop modifications are allowed between invocations of |
896 | C<release> and C<acquire> (that's their only purpose after all), no |
927 | C<release> and C<acquire> (that's their only purpose after all), no |
897 | modifications done will affect the event loop, i.e. adding watchers will |
928 | modifications done will affect the event loop, i.e. adding watchers will |
898 | have no effect on the set of file descriptors being watched, or the time |
929 | have no effect on the set of file descriptors being watched, or the time |
899 | waited. USe an C<ev_async> watcher to wake up C<ev_loop> when you want it |
930 | waited. Use an C<ev_async> watcher to wake up C<ev_loop> when you want it |
900 | to take note of any changes you made. |
931 | to take note of any changes you made. |
901 | |
932 | |
902 | In theory, threads executing C<ev_loop> will be async-cancel safe between |
933 | In theory, threads executing C<ev_loop> will be async-cancel safe between |
903 | invocations of C<release> and C<acquire>. |
934 | invocations of C<release> and C<acquire>. |
904 | |
935 | |
… | |
… | |
1101 | |
1132 | |
1102 | ev_io w; |
1133 | ev_io w; |
1103 | ev_init (&w, my_cb); |
1134 | ev_init (&w, my_cb); |
1104 | ev_io_set (&w, STDIN_FILENO, EV_READ); |
1135 | ev_io_set (&w, STDIN_FILENO, EV_READ); |
1105 | |
1136 | |
1106 | =item C<ev_TYPE_set> (ev_TYPE *, [args]) |
1137 | =item C<ev_TYPE_set> (ev_TYPE *watcher, [args]) |
1107 | |
1138 | |
1108 | This macro initialises the type-specific parts of a watcher. You need to |
1139 | This macro initialises the type-specific parts of a watcher. You need to |
1109 | call C<ev_init> at least once before you call this macro, but you can |
1140 | call C<ev_init> at least once before you call this macro, but you can |
1110 | call C<ev_TYPE_set> any number of times. You must not, however, call this |
1141 | call C<ev_TYPE_set> any number of times. You must not, however, call this |
1111 | macro on a watcher that is active (it can be pending, however, which is a |
1142 | macro on a watcher that is active (it can be pending, however, which is a |
… | |
… | |
1124 | |
1155 | |
1125 | Example: Initialise and set an C<ev_io> watcher in one step. |
1156 | Example: Initialise and set an C<ev_io> watcher in one step. |
1126 | |
1157 | |
1127 | ev_io_init (&w, my_cb, STDIN_FILENO, EV_READ); |
1158 | ev_io_init (&w, my_cb, STDIN_FILENO, EV_READ); |
1128 | |
1159 | |
1129 | =item C<ev_TYPE_start> (loop *, ev_TYPE *watcher) |
1160 | =item C<ev_TYPE_start> (loop, ev_TYPE *watcher) |
1130 | |
1161 | |
1131 | Starts (activates) the given watcher. Only active watchers will receive |
1162 | Starts (activates) the given watcher. Only active watchers will receive |
1132 | events. If the watcher is already active nothing will happen. |
1163 | events. If the watcher is already active nothing will happen. |
1133 | |
1164 | |
1134 | Example: Start the C<ev_io> watcher that is being abused as example in this |
1165 | Example: Start the C<ev_io> watcher that is being abused as example in this |
1135 | whole section. |
1166 | whole section. |
1136 | |
1167 | |
1137 | ev_io_start (EV_DEFAULT_UC, &w); |
1168 | ev_io_start (EV_DEFAULT_UC, &w); |
1138 | |
1169 | |
1139 | =item C<ev_TYPE_stop> (loop *, ev_TYPE *watcher) |
1170 | =item C<ev_TYPE_stop> (loop, ev_TYPE *watcher) |
1140 | |
1171 | |
1141 | Stops the given watcher if active, and clears the pending status (whether |
1172 | Stops the given watcher if active, and clears the pending status (whether |
1142 | the watcher was active or not). |
1173 | the watcher was active or not). |
1143 | |
1174 | |
1144 | It is possible that stopped watchers are pending - for example, |
1175 | It is possible that stopped watchers are pending - for example, |
… | |
… | |
1169 | =item ev_cb_set (ev_TYPE *watcher, callback) |
1200 | =item ev_cb_set (ev_TYPE *watcher, callback) |
1170 | |
1201 | |
1171 | Change the callback. You can change the callback at virtually any time |
1202 | Change the callback. You can change the callback at virtually any time |
1172 | (modulo threads). |
1203 | (modulo threads). |
1173 | |
1204 | |
1174 | =item ev_set_priority (ev_TYPE *watcher, priority) |
1205 | =item ev_set_priority (ev_TYPE *watcher, int priority) |
1175 | |
1206 | |
1176 | =item int ev_priority (ev_TYPE *watcher) |
1207 | =item int ev_priority (ev_TYPE *watcher) |
1177 | |
1208 | |
1178 | Set and query the priority of the watcher. The priority is a small |
1209 | Set and query the priority of the watcher. The priority is a small |
1179 | integer between C<EV_MAXPRI> (default: C<2>) and C<EV_MINPRI> |
1210 | integer between C<EV_MAXPRI> (default: C<2>) and C<EV_MINPRI> |
… | |
… | |
1210 | returns its C<revents> bitset (as if its callback was invoked). If the |
1241 | returns its C<revents> bitset (as if its callback was invoked). If the |
1211 | watcher isn't pending it does nothing and returns C<0>. |
1242 | watcher isn't pending it does nothing and returns C<0>. |
1212 | |
1243 | |
1213 | Sometimes it can be useful to "poll" a watcher instead of waiting for its |
1244 | Sometimes it can be useful to "poll" a watcher instead of waiting for its |
1214 | callback to be invoked, which can be accomplished with this function. |
1245 | callback to be invoked, which can be accomplished with this function. |
|
|
1246 | |
|
|
1247 | =item ev_feed_event (loop, ev_TYPE *watcher, int revents) |
|
|
1248 | |
|
|
1249 | Feeds the given event set into the event loop, as if the specified event |
|
|
1250 | had happened for the specified watcher (which must be a pointer to an |
|
|
1251 | initialised but not necessarily started event watcher). Obviously you must |
|
|
1252 | not free the watcher as long as it has pending events. |
|
|
1253 | |
|
|
1254 | Stopping the watcher, letting libev invoke it, or calling |
|
|
1255 | C<ev_clear_pending> will clear the pending event, even if the watcher was |
|
|
1256 | not started in the first place. |
|
|
1257 | |
|
|
1258 | See also C<ev_feed_fd_event> and C<ev_feed_signal_event> for related |
|
|
1259 | functions that do not need a watcher. |
1215 | |
1260 | |
1216 | =back |
1261 | =back |
1217 | |
1262 | |
1218 | |
1263 | |
1219 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
1264 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
… | |
… | |
1750 | |
1795 | |
1751 | If the event loop is suspended for a long time, you can also force an |
1796 | If the event loop is suspended for a long time, you can also force an |
1752 | update of the time returned by C<ev_now ()> by calling C<ev_now_update |
1797 | update of the time returned by C<ev_now ()> by calling C<ev_now_update |
1753 | ()>. |
1798 | ()>. |
1754 | |
1799 | |
|
|
1800 | =head3 The special problems of suspended animation |
|
|
1801 | |
|
|
1802 | When you leave the server world it is quite customary to hit machines that |
|
|
1803 | can suspend/hibernate - what happens to the clocks during such a suspend? |
|
|
1804 | |
|
|
1805 | Some quick tests made with a Linux 2.6.28 indicate that a suspend freezes |
|
|
1806 | all processes, while the clocks (C<times>, C<CLOCK_MONOTONIC>) continue |
|
|
1807 | to run until the system is suspended, but they will not advance while the |
|
|
1808 | system is suspended. That means, on resume, it will be as if the program |
|
|
1809 | was frozen for a few seconds, but the suspend time will not be counted |
|
|
1810 | towards C<ev_timer> when a monotonic clock source is used. The real time |
|
|
1811 | clock advanced as expected, but if it is used as sole clocksource, then a |
|
|
1812 | long suspend would be detected as a time jump by libev, and timers would |
|
|
1813 | be adjusted accordingly. |
|
|
1814 | |
|
|
1815 | I would not be surprised to see different behaviour in different between |
|
|
1816 | operating systems, OS versions or even different hardware. |
|
|
1817 | |
|
|
1818 | The other form of suspend (job control, or sending a SIGSTOP) will see a |
|
|
1819 | time jump in the monotonic clocks and the realtime clock. If the program |
|
|
1820 | is suspended for a very long time, and monotonic clock sources are in use, |
|
|
1821 | then you can expect C<ev_timer>s to expire as the full suspension time |
|
|
1822 | will be counted towards the timers. When no monotonic clock source is in |
|
|
1823 | use, then libev will again assume a timejump and adjust accordingly. |
|
|
1824 | |
|
|
1825 | It might be beneficial for this latter case to call C<ev_suspend> |
|
|
1826 | and C<ev_resume> in code that handles C<SIGTSTP>, to at least get |
|
|
1827 | deterministic behaviour in this case (you can do nothing against |
|
|
1828 | C<SIGSTOP>). |
|
|
1829 | |
1755 | =head3 Watcher-Specific Functions and Data Members |
1830 | =head3 Watcher-Specific Functions and Data Members |
1756 | |
1831 | |
1757 | =over 4 |
1832 | =over 4 |
1758 | |
1833 | |
1759 | =item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat) |
1834 | =item ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat) |
… | |
… | |
1784 | If the timer is repeating, either start it if necessary (with the |
1859 | If the timer is repeating, either start it if necessary (with the |
1785 | C<repeat> value), or reset the running timer to the C<repeat> value. |
1860 | C<repeat> value), or reset the running timer to the C<repeat> value. |
1786 | |
1861 | |
1787 | This sounds a bit complicated, see L<Be smart about timeouts>, above, for a |
1862 | This sounds a bit complicated, see L<Be smart about timeouts>, above, for a |
1788 | usage example. |
1863 | usage example. |
|
|
1864 | |
|
|
1865 | =item ev_tstamp ev_timer_remaining (loop, ev_timer *) |
|
|
1866 | |
|
|
1867 | Returns the remaining time until a timer fires. If the timer is active, |
|
|
1868 | then this time is relative to the current event loop time, otherwise it's |
|
|
1869 | the timeout value currently configured. |
|
|
1870 | |
|
|
1871 | That is, after an C<ev_timer_set (w, 5, 7)>, C<ev_timer_remaining> returns |
|
|
1872 | C<5>. When the timer is started and one second passes, C<ev_timer_remain> |
|
|
1873 | will return C<4>. When the timer expires and is restarted, it will return |
|
|
1874 | roughly C<7> (likely slightly less as callback invocation takes some time, |
|
|
1875 | too), and so on. |
1789 | |
1876 | |
1790 | =item ev_tstamp repeat [read-write] |
1877 | =item ev_tstamp repeat [read-write] |
1791 | |
1878 | |
1792 | The current C<repeat> value. Will be used each time the watcher times out |
1879 | The current C<repeat> value. Will be used each time the watcher times out |
1793 | or C<ev_timer_again> is called, and determines the next timeout (if any), |
1880 | or C<ev_timer_again> is called, and determines the next timeout (if any), |
… | |
… | |
2029 | Signal watchers will trigger an event when the process receives a specific |
2116 | Signal watchers will trigger an event when the process receives a specific |
2030 | signal one or more times. Even though signals are very asynchronous, libev |
2117 | signal one or more times. Even though signals are very asynchronous, libev |
2031 | will try it's best to deliver signals synchronously, i.e. as part of the |
2118 | will try it's best to deliver signals synchronously, i.e. as part of the |
2032 | normal event processing, like any other event. |
2119 | normal event processing, like any other event. |
2033 | |
2120 | |
2034 | If you want signals asynchronously, just use C<sigaction> as you would |
2121 | If you want signals to be delivered truly asynchronously, just use |
2035 | do without libev and forget about sharing the signal. You can even use |
2122 | C<sigaction> as you would do without libev and forget about sharing |
2036 | C<ev_async> from a signal handler to synchronously wake up an event loop. |
2123 | the signal. You can even use C<ev_async> from a signal handler to |
|
|
2124 | synchronously wake up an event loop. |
2037 | |
2125 | |
2038 | You can configure as many watchers as you like per signal. Only when the |
2126 | You can configure as many watchers as you like for the same signal, but |
|
|
2127 | only within the same loop, i.e. you can watch for C<SIGINT> in your |
|
|
2128 | default loop and for C<SIGIO> in another loop, but you cannot watch for |
|
|
2129 | C<SIGINT> in both the default loop and another loop at the same time. At |
|
|
2130 | the moment, C<SIGCHLD> is permanently tied to the default loop. |
|
|
2131 | |
2039 | first watcher gets started will libev actually register a signal handler |
2132 | When the first watcher gets started will libev actually register something |
2040 | with the kernel (thus it coexists with your own signal handlers as long as |
2133 | with the kernel (thus it coexists with your own signal handlers as long as |
2041 | you don't register any with libev for the same signal). Similarly, when |
2134 | you don't register any with libev for the same signal). |
2042 | the last signal watcher for a signal is stopped, libev will reset the |
|
|
2043 | signal handler to SIG_DFL (regardless of what it was set to before). |
|
|
2044 | |
2135 | |
2045 | If possible and supported, libev will install its handlers with |
2136 | If possible and supported, libev will install its handlers with |
2046 | C<SA_RESTART> behaviour enabled, so system calls should not be unduly |
2137 | C<SA_RESTART> (or equivalent) behaviour enabled, so system calls should |
2047 | interrupted. If you have a problem with system calls getting interrupted by |
2138 | not be unduly interrupted. If you have a problem with system calls getting |
2048 | signals you can block all signals in an C<ev_check> watcher and unblock |
2139 | interrupted by signals you can block all signals in an C<ev_check> watcher |
2049 | them in an C<ev_prepare> watcher. |
2140 | and unblock them in an C<ev_prepare> watcher. |
|
|
2141 | |
|
|
2142 | =head3 The special problem of inheritance over fork/execve/pthread_create |
|
|
2143 | |
|
|
2144 | Both the signal mask (C<sigprocmask>) and the signal disposition |
|
|
2145 | (C<sigaction>) are unspecified after starting a signal watcher (and after |
|
|
2146 | stopping it again), that is, libev might or might not block the signal, |
|
|
2147 | and might or might not set or restore the installed signal handler. |
|
|
2148 | |
|
|
2149 | While this does not matter for the signal disposition (libev never |
|
|
2150 | sets signals to C<SIG_IGN>, so handlers will be reset to C<SIG_DFL> on |
|
|
2151 | C<execve>), this matters for the signal mask: many programs do not expect |
|
|
2152 | certain signals to be blocked. |
|
|
2153 | |
|
|
2154 | This means that before calling C<exec> (from the child) you should reset |
|
|
2155 | the signal mask to whatever "default" you expect (all clear is a good |
|
|
2156 | choice usually). |
|
|
2157 | |
|
|
2158 | The simplest way to ensure that the signal mask is reset in the child is |
|
|
2159 | to install a fork handler with C<pthread_atfork> that resets it. That will |
|
|
2160 | catch fork calls done by libraries (such as the libc) as well. |
|
|
2161 | |
|
|
2162 | In current versions of libev, the signal will not be blocked indefinitely |
|
|
2163 | unless you use the C<signalfd> API (C<EV_SIGNALFD>). While this reduces |
|
|
2164 | the window of opportunity for problems, it will not go away, as libev |
|
|
2165 | I<has> to modify the signal mask, at least temporarily. |
|
|
2166 | |
|
|
2167 | So I can't stress this enough: I<If you do not reset your signal mask when |
|
|
2168 | you expect it to be empty, you have a race condition in your code>. This |
|
|
2169 | is not a libev-specific thing, this is true for most event libraries. |
2050 | |
2170 | |
2051 | =head3 Watcher-Specific Functions and Data Members |
2171 | =head3 Watcher-Specific Functions and Data Members |
2052 | |
2172 | |
2053 | =over 4 |
2173 | =over 4 |
2054 | |
2174 | |
… | |
… | |
2099 | libev) |
2219 | libev) |
2100 | |
2220 | |
2101 | =head3 Process Interaction |
2221 | =head3 Process Interaction |
2102 | |
2222 | |
2103 | Libev grabs C<SIGCHLD> as soon as the default event loop is |
2223 | Libev grabs C<SIGCHLD> as soon as the default event loop is |
2104 | initialised. This is necessary to guarantee proper behaviour even if |
2224 | initialised. This is necessary to guarantee proper behaviour even if the |
2105 | the first child watcher is started after the child exits. The occurrence |
2225 | first child watcher is started after the child exits. The occurrence |
2106 | of C<SIGCHLD> is recorded asynchronously, but child reaping is done |
2226 | of C<SIGCHLD> is recorded asynchronously, but child reaping is done |
2107 | synchronously as part of the event loop processing. Libev always reaps all |
2227 | synchronously as part of the event loop processing. Libev always reaps all |
2108 | children, even ones not watched. |
2228 | children, even ones not watched. |
2109 | |
2229 | |
2110 | =head3 Overriding the Built-In Processing |
2230 | =head3 Overriding the Built-In Processing |
… | |
… | |
2120 | =head3 Stopping the Child Watcher |
2240 | =head3 Stopping the Child Watcher |
2121 | |
2241 | |
2122 | Currently, the child watcher never gets stopped, even when the |
2242 | Currently, the child watcher never gets stopped, even when the |
2123 | child terminates, so normally one needs to stop the watcher in the |
2243 | child terminates, so normally one needs to stop the watcher in the |
2124 | callback. Future versions of libev might stop the watcher automatically |
2244 | callback. Future versions of libev might stop the watcher automatically |
2125 | when a child exit is detected. |
2245 | when a child exit is detected (calling C<ev_child_stop> twice is not a |
|
|
2246 | problem). |
2126 | |
2247 | |
2127 | =head3 Watcher-Specific Functions and Data Members |
2248 | =head3 Watcher-Specific Functions and Data Members |
2128 | |
2249 | |
2129 | =over 4 |
2250 | =over 4 |
2130 | |
2251 | |
… | |
… | |
2870 | =head3 Queueing |
2991 | =head3 Queueing |
2871 | |
2992 | |
2872 | C<ev_async> does not support queueing of data in any way. The reason |
2993 | C<ev_async> does not support queueing of data in any way. The reason |
2873 | is that the author does not know of a simple (or any) algorithm for a |
2994 | is that the author does not know of a simple (or any) algorithm for a |
2874 | multiple-writer-single-reader queue that works in all cases and doesn't |
2995 | multiple-writer-single-reader queue that works in all cases and doesn't |
2875 | need elaborate support such as pthreads. |
2996 | need elaborate support such as pthreads or unportable memory access |
|
|
2997 | semantics. |
2876 | |
2998 | |
2877 | That means that if you want to queue data, you have to provide your own |
2999 | That means that if you want to queue data, you have to provide your own |
2878 | queue. But at least I can tell you how to implement locking around your |
3000 | queue. But at least I can tell you how to implement locking around your |
2879 | queue: |
3001 | queue: |
2880 | |
3002 | |
… | |
… | |
3038 | /* doh, nothing entered */; |
3160 | /* doh, nothing entered */; |
3039 | } |
3161 | } |
3040 | |
3162 | |
3041 | ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
3163 | ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
3042 | |
3164 | |
3043 | =item ev_feed_event (struct ev_loop *, watcher *, int revents) |
|
|
3044 | |
|
|
3045 | Feeds the given event set into the event loop, as if the specified event |
|
|
3046 | had happened for the specified watcher (which must be a pointer to an |
|
|
3047 | initialised but not necessarily started event watcher). |
|
|
3048 | |
|
|
3049 | =item ev_feed_fd_event (struct ev_loop *, int fd, int revents) |
3165 | =item ev_feed_fd_event (loop, int fd, int revents) |
3050 | |
3166 | |
3051 | Feed an event on the given fd, as if a file descriptor backend detected |
3167 | Feed an event on the given fd, as if a file descriptor backend detected |
3052 | the given events it. |
3168 | the given events it. |
3053 | |
3169 | |
3054 | =item ev_feed_signal_event (struct ev_loop *loop, int signum) |
3170 | =item ev_feed_signal_event (loop, int signum) |
3055 | |
3171 | |
3056 | Feed an event as if the given signal occurred (C<loop> must be the default |
3172 | Feed an event as if the given signal occurred (C<loop> must be the default |
3057 | loop!). |
3173 | loop!). |
3058 | |
3174 | |
3059 | =back |
3175 | =back |
… | |
… | |
3139 | |
3255 | |
3140 | =over 4 |
3256 | =over 4 |
3141 | |
3257 | |
3142 | =item ev::TYPE::TYPE () |
3258 | =item ev::TYPE::TYPE () |
3143 | |
3259 | |
3144 | =item ev::TYPE::TYPE (struct ev_loop *) |
3260 | =item ev::TYPE::TYPE (loop) |
3145 | |
3261 | |
3146 | =item ev::TYPE::~TYPE |
3262 | =item ev::TYPE::~TYPE |
3147 | |
3263 | |
3148 | The constructor (optionally) takes an event loop to associate the watcher |
3264 | The constructor (optionally) takes an event loop to associate the watcher |
3149 | with. If it is omitted, it will use C<EV_DEFAULT>. |
3265 | with. If it is omitted, it will use C<EV_DEFAULT>. |
… | |
… | |
3226 | Example: Use a plain function as callback. |
3342 | Example: Use a plain function as callback. |
3227 | |
3343 | |
3228 | static void io_cb (ev::io &w, int revents) { } |
3344 | static void io_cb (ev::io &w, int revents) { } |
3229 | iow.set <io_cb> (); |
3345 | iow.set <io_cb> (); |
3230 | |
3346 | |
3231 | =item w->set (struct ev_loop *) |
3347 | =item w->set (loop) |
3232 | |
3348 | |
3233 | Associates a different C<struct ev_loop> with this watcher. You can only |
3349 | Associates a different C<struct ev_loop> with this watcher. You can only |
3234 | do this when the watcher is inactive (and not pending either). |
3350 | do this when the watcher is inactive (and not pending either). |
3235 | |
3351 | |
3236 | =item w->set ([arguments]) |
3352 | =item w->set ([arguments]) |
… | |
… | |
3333 | =item Ocaml |
3449 | =item Ocaml |
3334 | |
3450 | |
3335 | Erkki Seppala has written Ocaml bindings for libev, to be found at |
3451 | Erkki Seppala has written Ocaml bindings for libev, to be found at |
3336 | L<http://modeemi.cs.tut.fi/~flux/software/ocaml-ev/>. |
3452 | L<http://modeemi.cs.tut.fi/~flux/software/ocaml-ev/>. |
3337 | |
3453 | |
|
|
3454 | =item Lua |
|
|
3455 | |
|
|
3456 | Brian Maher has written a partial interface to libev for lua (at the |
|
|
3457 | time of this writing, only C<ev_io> and C<ev_timer>), to be found at |
|
|
3458 | L<http://github.com/brimworks/lua-ev>. |
|
|
3459 | |
3338 | =back |
3460 | =back |
3339 | |
3461 | |
3340 | |
3462 | |
3341 | =head1 MACRO MAGIC |
3463 | =head1 MACRO MAGIC |
3342 | |
3464 | |
… | |
… | |
3508 | keeps libev from including F<config.h>, and it also defines dummy |
3630 | keeps libev from including F<config.h>, and it also defines dummy |
3509 | implementations for some libevent functions (such as logging, which is not |
3631 | implementations for some libevent functions (such as logging, which is not |
3510 | supported). It will also not define any of the structs usually found in |
3632 | supported). It will also not define any of the structs usually found in |
3511 | F<event.h> that are not directly supported by the libev core alone. |
3633 | F<event.h> that are not directly supported by the libev core alone. |
3512 | |
3634 | |
3513 | In stanbdalone mode, libev will still try to automatically deduce the |
3635 | In standalone mode, libev will still try to automatically deduce the |
3514 | configuration, but has to be more conservative. |
3636 | configuration, but has to be more conservative. |
3515 | |
3637 | |
3516 | =item EV_USE_MONOTONIC |
3638 | =item EV_USE_MONOTONIC |
3517 | |
3639 | |
3518 | If defined to be C<1>, libev will try to detect the availability of the |
3640 | If defined to be C<1>, libev will try to detect the availability of the |
… | |
… | |
3583 | be used is the winsock select). This means that it will call |
3705 | be used is the winsock select). This means that it will call |
3584 | C<_get_osfhandle> on the fd to convert it to an OS handle. Otherwise, |
3706 | C<_get_osfhandle> on the fd to convert it to an OS handle. Otherwise, |
3585 | it is assumed that all these functions actually work on fds, even |
3707 | it is assumed that all these functions actually work on fds, even |
3586 | on win32. Should not be defined on non-win32 platforms. |
3708 | on win32. Should not be defined on non-win32 platforms. |
3587 | |
3709 | |
3588 | =item EV_FD_TO_WIN32_HANDLE |
3710 | =item EV_FD_TO_WIN32_HANDLE(fd) |
3589 | |
3711 | |
3590 | If C<EV_SELECT_IS_WINSOCKET> is enabled, then libev needs a way to map |
3712 | If C<EV_SELECT_IS_WINSOCKET> is enabled, then libev needs a way to map |
3591 | file descriptors to socket handles. When not defining this symbol (the |
3713 | file descriptors to socket handles. When not defining this symbol (the |
3592 | default), then libev will call C<_get_osfhandle>, which is usually |
3714 | default), then libev will call C<_get_osfhandle>, which is usually |
3593 | correct. In some cases, programs use their own file descriptor management, |
3715 | correct. In some cases, programs use their own file descriptor management, |
3594 | in which case they can provide this function to map fds to socket handles. |
3716 | in which case they can provide this function to map fds to socket handles. |
|
|
3717 | |
|
|
3718 | =item EV_WIN32_HANDLE_TO_FD(handle) |
|
|
3719 | |
|
|
3720 | If C<EV_SELECT_IS_WINSOCKET> then libev maps handles to file descriptors |
|
|
3721 | using the standard C<_open_osfhandle> function. For programs implementing |
|
|
3722 | their own fd to handle mapping, overwriting this function makes it easier |
|
|
3723 | to do so. This can be done by defining this macro to an appropriate value. |
|
|
3724 | |
|
|
3725 | =item EV_WIN32_CLOSE_FD(fd) |
|
|
3726 | |
|
|
3727 | If programs implement their own fd to handle mapping on win32, then this |
|
|
3728 | macro can be used to override the C<close> function, useful to unregister |
|
|
3729 | file descriptors again. Note that the replacement function has to close |
|
|
3730 | the underlying OS handle. |
3595 | |
3731 | |
3596 | =item EV_USE_POLL |
3732 | =item EV_USE_POLL |
3597 | |
3733 | |
3598 | If defined to be C<1>, libev will compile in support for the C<poll>(2) |
3734 | If defined to be C<1>, libev will compile in support for the C<poll>(2) |
3599 | backend. Otherwise it will be enabled on non-win32 platforms. It |
3735 | backend. Otherwise it will be enabled on non-win32 platforms. It |
… | |
… | |
3745 | Defining C<EV_MINIMAL> to C<2> will additionally reduce the core API to |
3881 | Defining C<EV_MINIMAL> to C<2> will additionally reduce the core API to |
3746 | provide a bare-bones event library. See C<ev.h> for details on what parts |
3882 | provide a bare-bones event library. See C<ev.h> for details on what parts |
3747 | of the API are still available, and do not complain if this subset changes |
3883 | of the API are still available, and do not complain if this subset changes |
3748 | over time. |
3884 | over time. |
3749 | |
3885 | |
|
|
3886 | =item EV_NSIG |
|
|
3887 | |
|
|
3888 | The highest supported signal number, +1 (or, the number of |
|
|
3889 | signals): Normally, libev tries to deduce the maximum number of signals |
|
|
3890 | automatically, but sometimes this fails, in which case it can be |
|
|
3891 | specified. Also, using a lower number than detected (C<32> should be |
|
|
3892 | good for about any system in existance) can save some memory, as libev |
|
|
3893 | statically allocates some 12-24 bytes per signal number. |
|
|
3894 | |
3750 | =item EV_PID_HASHSIZE |
3895 | =item EV_PID_HASHSIZE |
3751 | |
3896 | |
3752 | C<ev_child> watchers use a small hash table to distribute workload by |
3897 | C<ev_child> watchers use a small hash table to distribute workload by |
3753 | pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more |
3898 | pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more |
3754 | than enough. If you need to manage thousands of children you might want to |
3899 | than enough. If you need to manage thousands of children you might want to |
… | |
… | |
3998 | protecting the loop data, respectively. |
4143 | protecting the loop data, respectively. |
3999 | |
4144 | |
4000 | static void |
4145 | static void |
4001 | l_release (EV_P) |
4146 | l_release (EV_P) |
4002 | { |
4147 | { |
4003 | udat *u = ev_userdata (EV_A); |
4148 | userdata *u = ev_userdata (EV_A); |
4004 | pthread_mutex_unlock (&u->lock); |
4149 | pthread_mutex_unlock (&u->lock); |
4005 | } |
4150 | } |
4006 | |
4151 | |
4007 | static void |
4152 | static void |
4008 | l_acquire (EV_P) |
4153 | l_acquire (EV_P) |
4009 | { |
4154 | { |
4010 | udat *u = ev_userdata (EV_A); |
4155 | userdata *u = ev_userdata (EV_A); |
4011 | pthread_mutex_lock (&u->lock); |
4156 | pthread_mutex_lock (&u->lock); |
4012 | } |
4157 | } |
4013 | |
4158 | |
4014 | The event loop thread first acquires the mutex, and then jumps straight |
4159 | The event loop thread first acquires the mutex, and then jumps straight |
4015 | into C<ev_loop>: |
4160 | into C<ev_loop>: |
… | |
… | |
4028 | } |
4173 | } |
4029 | |
4174 | |
4030 | Instead of invoking all pending watchers, the C<l_invoke> callback will |
4175 | Instead of invoking all pending watchers, the C<l_invoke> callback will |
4031 | signal the main thread via some unspecified mechanism (signals? pipe |
4176 | signal the main thread via some unspecified mechanism (signals? pipe |
4032 | writes? C<Async::Interrupt>?) and then waits until all pending watchers |
4177 | writes? C<Async::Interrupt>?) and then waits until all pending watchers |
4033 | have been called: |
4178 | have been called (in a while loop because a) spurious wakeups are possible |
|
|
4179 | and b) skipping inter-thread-communication when there are no pending |
|
|
4180 | watchers is very beneficial): |
4034 | |
4181 | |
4035 | static void |
4182 | static void |
4036 | l_invoke (EV_P) |
4183 | l_invoke (EV_P) |
4037 | { |
4184 | { |
4038 | udat *u = ev_userdata (EV_A); |
4185 | userdata *u = ev_userdata (EV_A); |
4039 | |
4186 | |
|
|
4187 | while (ev_pending_count (EV_A)) |
|
|
4188 | { |
4040 | wake_up_other_thread_in_some_magic_or_not_so_magic_way (); |
4189 | wake_up_other_thread_in_some_magic_or_not_so_magic_way (); |
4041 | |
|
|
4042 | pthread_cond_wait (&u->invoke_cv, &u->lock); |
4190 | pthread_cond_wait (&u->invoke_cv, &u->lock); |
|
|
4191 | } |
4043 | } |
4192 | } |
4044 | |
4193 | |
4045 | Now, whenever the main thread gets told to invoke pending watchers, it |
4194 | Now, whenever the main thread gets told to invoke pending watchers, it |
4046 | will grab the lock, call C<ev_invoke_pending> and then signal the loop |
4195 | will grab the lock, call C<ev_invoke_pending> and then signal the loop |
4047 | thread to continue: |
4196 | thread to continue: |
4048 | |
4197 | |
4049 | static void |
4198 | static void |
4050 | real_invoke_pending (EV_P) |
4199 | real_invoke_pending (EV_P) |
4051 | { |
4200 | { |
4052 | udat *u = ev_userdata (EV_A); |
4201 | userdata *u = ev_userdata (EV_A); |
4053 | |
4202 | |
4054 | pthread_mutex_lock (&u->lock); |
4203 | pthread_mutex_lock (&u->lock); |
4055 | ev_invoke_pending (EV_A); |
4204 | ev_invoke_pending (EV_A); |
4056 | pthread_cond_signal (&u->invoke_cv); |
4205 | pthread_cond_signal (&u->invoke_cv); |
4057 | pthread_mutex_unlock (&u->lock); |
4206 | pthread_mutex_unlock (&u->lock); |
… | |
… | |
4059 | |
4208 | |
4060 | Whenever you want to start/stop a watcher or do other modifications to an |
4209 | Whenever you want to start/stop a watcher or do other modifications to an |
4061 | event loop, you will now have to lock: |
4210 | event loop, you will now have to lock: |
4062 | |
4211 | |
4063 | ev_timer timeout_watcher; |
4212 | ev_timer timeout_watcher; |
4064 | udat *u = ev_userdata (EV_A); |
4213 | userdata *u = ev_userdata (EV_A); |
4065 | |
4214 | |
4066 | ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.); |
4215 | ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.); |
4067 | |
4216 | |
4068 | pthread_mutex_lock (&u->lock); |
4217 | pthread_mutex_lock (&u->lock); |
4069 | ev_timer_start (EV_A_ &timeout_watcher); |
4218 | ev_timer_start (EV_A_ &timeout_watcher); |
… | |
… | |
4078 | =head3 COROUTINES |
4227 | =head3 COROUTINES |
4079 | |
4228 | |
4080 | Libev is very accommodating to coroutines ("cooperative threads"): |
4229 | Libev is very accommodating to coroutines ("cooperative threads"): |
4081 | libev fully supports nesting calls to its functions from different |
4230 | libev fully supports nesting calls to its functions from different |
4082 | coroutines (e.g. you can call C<ev_loop> on the same loop from two |
4231 | coroutines (e.g. you can call C<ev_loop> on the same loop from two |
4083 | different coroutines, and switch freely between both coroutines running the |
4232 | different coroutines, and switch freely between both coroutines running |
4084 | loop, as long as you don't confuse yourself). The only exception is that |
4233 | the loop, as long as you don't confuse yourself). The only exception is |
4085 | you must not do this from C<ev_periodic> reschedule callbacks. |
4234 | that you must not do this from C<ev_periodic> reschedule callbacks. |
4086 | |
4235 | |
4087 | Care has been taken to ensure that libev does not keep local state inside |
4236 | Care has been taken to ensure that libev does not keep local state inside |
4088 | C<ev_loop>, and other calls do not usually allow for coroutine switches as |
4237 | C<ev_loop>, and other calls do not usually allow for coroutine switches as |
4089 | they do not call any callbacks. |
4238 | they do not call any callbacks. |
4090 | |
4239 | |