|
|
1 | =encoding utf-8 |
|
|
2 | |
1 | =head1 NAME |
3 | =head1 NAME |
2 | |
4 | |
3 | libev - a high performance full-featured event loop written in C |
5 | libev - a high performance full-featured event loop written in C |
4 | |
6 | |
5 | =head1 SYNOPSIS |
7 | =head1 SYNOPSIS |
… | |
… | |
82 | |
84 | |
83 | =head1 WHAT TO READ WHEN IN A HURRY |
85 | =head1 WHAT TO READ WHEN IN A HURRY |
84 | |
86 | |
85 | This manual tries to be very detailed, but unfortunately, this also makes |
87 | 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 |
88 | 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 |
89 | 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 |
90 | look up the missing functions in L</GLOBAL FUNCTIONS> and the C<ev_io> and |
89 | C<ev_timer> sections in L<WATCHER TYPES>. |
91 | C<ev_timer> sections in L</WATCHER TYPES>. |
90 | |
92 | |
91 | =head1 ABOUT LIBEV |
93 | =head1 ABOUT LIBEV |
92 | |
94 | |
93 | Libev is an event loop: you register interest in certain events (such as a |
95 | 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 |
96 | file descriptor being readable or a timeout occurring), and it will manage |
… | |
… | |
396 | |
398 | |
397 | If this flag bit is or'ed into the flag value (or the program runs setuid |
399 | If this flag bit is or'ed into the flag value (or the program runs setuid |
398 | or setgid) then libev will I<not> look at the environment variable |
400 | or setgid) then libev will I<not> look at the environment variable |
399 | C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will |
401 | C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will |
400 | override the flags completely if it is found in the environment. This is |
402 | override the flags completely if it is found in the environment. This is |
401 | useful to try out specific backends to test their performance, or to work |
403 | useful to try out specific backends to test their performance, to work |
402 | around bugs. |
404 | around bugs, or to make libev threadsafe (accessing environment variables |
|
|
405 | cannot be done in a threadsafe way, but usually it works if no other |
|
|
406 | thread modifies them). |
403 | |
407 | |
404 | =item C<EVFLAG_FORKCHECK> |
408 | =item C<EVFLAG_FORKCHECK> |
405 | |
409 | |
406 | Instead of calling C<ev_loop_fork> manually after a fork, you can also |
410 | Instead of calling C<ev_loop_fork> manually after a fork, you can also |
407 | make libev check for a fork in each iteration by enabling this flag. |
411 | make libev check for a fork in each iteration by enabling this flag. |
… | |
… | |
569 | kernel is more efficient (which says nothing about its actual speed, of |
573 | 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 |
574 | 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 |
575 | 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 (you |
576 | two event changes per incident. Support for C<fork ()> is very bad (you |
573 | might have to leak fd's on fork, but it's more sane than epoll) and it |
577 | might have to leak fd's on fork, but it's more sane than epoll) and it |
574 | drops fds silently in similarly hard-to-detect cases |
578 | drops fds silently in similarly hard-to-detect cases. |
575 | |
579 | |
576 | This backend usually performs well under most conditions. |
580 | This backend usually performs well under most conditions. |
577 | |
581 | |
578 | While nominally embeddable in other event loops, this doesn't work |
582 | 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 |
583 | everywhere, so you might need to test for this. And since it is broken |
… | |
… | |
684 | reinitialise the kernel state for backends that have one. Despite the |
688 | reinitialise the kernel state for backends that have one. Despite the |
685 | name, you can call it anytime, but it makes most sense after forking, in |
689 | name, you can call it anytime, but it makes most sense after forking, in |
686 | the child process. You I<must> call it (or use C<EVFLAG_FORKCHECK>) in the |
690 | the child process. You I<must> call it (or use C<EVFLAG_FORKCHECK>) in the |
687 | child before resuming or calling C<ev_run>. |
691 | child before resuming or calling C<ev_run>. |
688 | |
692 | |
689 | Again, you I<have> to call it on I<any> loop that you want to re-use after |
693 | Again, you I<have> to call it on I<any> loop that you want to re-use after |
690 | a fork, I<even if you do not plan to use the loop in the parent>. This is |
694 | a fork, I<even if you do not plan to use the loop in the parent>. This is |
691 | because some kernel interfaces *cough* I<kqueue> *cough* do funny things |
695 | because some kernel interfaces *cough* I<kqueue> *cough* do funny things |
692 | during fork. |
696 | during fork. |
693 | |
697 | |
694 | On the other hand, you only need to call this function in the child |
698 | On the other hand, you only need to call this function in the child |
… | |
… | |
764 | |
768 | |
765 | This function is rarely useful, but when some event callback runs for a |
769 | 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 |
770 | very long time without entering the event loop, updating libev's idea of |
767 | the current time is a good idea. |
771 | the current time is a good idea. |
768 | |
772 | |
769 | See also L<The special problem of time updates> in the C<ev_timer> section. |
773 | See also L</The special problem of time updates> in the C<ev_timer> section. |
770 | |
774 | |
771 | =item ev_suspend (loop) |
775 | =item ev_suspend (loop) |
772 | |
776 | |
773 | =item ev_resume (loop) |
777 | =item ev_resume (loop) |
774 | |
778 | |
… | |
… | |
1174 | |
1178 | |
1175 | =item C<EV_PREPARE> |
1179 | =item C<EV_PREPARE> |
1176 | |
1180 | |
1177 | =item C<EV_CHECK> |
1181 | =item C<EV_CHECK> |
1178 | |
1182 | |
1179 | All C<ev_prepare> watchers are invoked just I<before> C<ev_run> starts |
1183 | All C<ev_prepare> watchers are invoked just I<before> C<ev_run> starts to |
1180 | to gather new events, and all C<ev_check> watchers are invoked just after |
1184 | gather new events, and all C<ev_check> watchers are queued (not invoked) |
1181 | C<ev_run> has gathered them, but before it invokes any callbacks for any |
1185 | just after C<ev_run> has gathered them, but before it queues any callbacks |
|
|
1186 | for any received events. That means C<ev_prepare> watchers are the last |
|
|
1187 | watchers invoked before the event loop sleeps or polls for new events, and |
|
|
1188 | C<ev_check> watchers will be invoked before any other watchers of the same |
|
|
1189 | or lower priority within an event loop iteration. |
|
|
1190 | |
1182 | received events. Callbacks of both watcher types can start and stop as |
1191 | Callbacks of both watcher types can start and stop as many watchers as |
1183 | many watchers as they want, and all of them will be taken into account |
1192 | they want, and all of them will be taken into account (for example, a |
1184 | (for example, a C<ev_prepare> watcher might start an idle watcher to keep |
1193 | C<ev_prepare> watcher might start an idle watcher to keep C<ev_run> from |
1185 | C<ev_run> from blocking). |
1194 | blocking). |
1186 | |
1195 | |
1187 | =item C<EV_EMBED> |
1196 | =item C<EV_EMBED> |
1188 | |
1197 | |
1189 | The embedded event loop specified in the C<ev_embed> watcher needs attention. |
1198 | The embedded event loop specified in the C<ev_embed> watcher needs attention. |
1190 | |
1199 | |
… | |
… | |
1313 | |
1322 | |
1314 | =item callback ev_cb (ev_TYPE *watcher) |
1323 | =item callback ev_cb (ev_TYPE *watcher) |
1315 | |
1324 | |
1316 | Returns the callback currently set on the watcher. |
1325 | Returns the callback currently set on the watcher. |
1317 | |
1326 | |
1318 | =item ev_cb_set (ev_TYPE *watcher, callback) |
1327 | =item ev_set_cb (ev_TYPE *watcher, callback) |
1319 | |
1328 | |
1320 | Change the callback. You can change the callback at virtually any time |
1329 | Change the callback. You can change the callback at virtually any time |
1321 | (modulo threads). |
1330 | (modulo threads). |
1322 | |
1331 | |
1323 | =item ev_set_priority (ev_TYPE *watcher, int priority) |
1332 | =item ev_set_priority (ev_TYPE *watcher, int priority) |
… | |
… | |
1341 | or might not have been clamped to the valid range. |
1350 | or might not have been clamped to the valid range. |
1342 | |
1351 | |
1343 | The default priority used by watchers when no priority has been set is |
1352 | The default priority used by watchers when no priority has been set is |
1344 | always C<0>, which is supposed to not be too high and not be too low :). |
1353 | always C<0>, which is supposed to not be too high and not be too low :). |
1345 | |
1354 | |
1346 | See L<WATCHER PRIORITY MODELS>, below, for a more thorough treatment of |
1355 | See L</WATCHER PRIORITY MODELS>, below, for a more thorough treatment of |
1347 | priorities. |
1356 | priorities. |
1348 | |
1357 | |
1349 | =item ev_invoke (loop, ev_TYPE *watcher, int revents) |
1358 | =item ev_invoke (loop, ev_TYPE *watcher, int revents) |
1350 | |
1359 | |
1351 | Invoke the C<watcher> with the given C<loop> and C<revents>. Neither |
1360 | Invoke the C<watcher> with the given C<loop> and C<revents>. Neither |
… | |
… | |
1376 | See also C<ev_feed_fd_event> and C<ev_feed_signal_event> for related |
1385 | See also C<ev_feed_fd_event> and C<ev_feed_signal_event> for related |
1377 | functions that do not need a watcher. |
1386 | functions that do not need a watcher. |
1378 | |
1387 | |
1379 | =back |
1388 | =back |
1380 | |
1389 | |
1381 | See also the L<ASSOCIATING CUSTOM DATA WITH A WATCHER> and L<BUILDING YOUR |
1390 | See also the L</ASSOCIATING CUSTOM DATA WITH A WATCHER> and L</BUILDING YOUR |
1382 | OWN COMPOSITE WATCHERS> idioms. |
1391 | OWN COMPOSITE WATCHERS> idioms. |
1383 | |
1392 | |
1384 | =head2 WATCHER STATES |
1393 | =head2 WATCHER STATES |
1385 | |
1394 | |
1386 | There are various watcher states mentioned throughout this manual - |
1395 | There are various watcher states mentioned throughout this manual - |
… | |
… | |
1388 | transition between them will be described in more detail - and while these |
1397 | transition between them will be described in more detail - and while these |
1389 | rules might look complicated, they usually do "the right thing". |
1398 | rules might look complicated, they usually do "the right thing". |
1390 | |
1399 | |
1391 | =over 4 |
1400 | =over 4 |
1392 | |
1401 | |
1393 | =item initialiased |
1402 | =item initialised |
1394 | |
1403 | |
1395 | Before a watcher can be registered with the event loop it has to be |
1404 | Before a watcher can be registered with the event loop it has to be |
1396 | initialised. This can be done with a call to C<ev_TYPE_init>, or calls to |
1405 | initialised. This can be done with a call to C<ev_TYPE_init>, or calls to |
1397 | C<ev_init> followed by the watcher-specific C<ev_TYPE_set> function. |
1406 | C<ev_init> followed by the watcher-specific C<ev_TYPE_set> function. |
1398 | |
1407 | |
… | |
… | |
2131 | =item If the timer is repeating, make the C<repeat> value the new timeout |
2140 | =item If the timer is repeating, make the C<repeat> value the new timeout |
2132 | and start the timer, if necessary. |
2141 | and start the timer, if necessary. |
2133 | |
2142 | |
2134 | =back |
2143 | =back |
2135 | |
2144 | |
2136 | This sounds a bit complicated, see L<Be smart about timeouts>, above, for a |
2145 | This sounds a bit complicated, see L</Be smart about timeouts>, above, for a |
2137 | usage example. |
2146 | usage example. |
2138 | |
2147 | |
2139 | =item ev_tstamp ev_timer_remaining (loop, ev_timer *) |
2148 | =item ev_tstamp ev_timer_remaining (loop, ev_timer *) |
2140 | |
2149 | |
2141 | Returns the remaining time until a timer fires. If the timer is active, |
2150 | Returns the remaining time until a timer fires. If the timer is active, |
… | |
… | |
2601 | |
2610 | |
2602 | =head2 C<ev_stat> - did the file attributes just change? |
2611 | =head2 C<ev_stat> - did the file attributes just change? |
2603 | |
2612 | |
2604 | This watches a file system path for attribute changes. That is, it calls |
2613 | This watches a file system path for attribute changes. That is, it calls |
2605 | C<stat> on that path in regular intervals (or when the OS says it changed) |
2614 | C<stat> on that path in regular intervals (or when the OS says it changed) |
2606 | and sees if it changed compared to the last time, invoking the callback if |
2615 | and sees if it changed compared to the last time, invoking the callback |
2607 | it did. |
2616 | if it did. Starting the watcher C<stat>'s the file, so only changes that |
|
|
2617 | happen after the watcher has been started will be reported. |
2608 | |
2618 | |
2609 | The path does not need to exist: changing from "path exists" to "path does |
2619 | The path does not need to exist: changing from "path exists" to "path does |
2610 | not exist" is a status change like any other. The condition "path does not |
2620 | not exist" is a status change like any other. The condition "path does not |
2611 | exist" (or more correctly "path cannot be stat'ed") is signified by the |
2621 | exist" (or more correctly "path cannot be stat'ed") is signified by the |
2612 | C<st_nlink> field being zero (which is otherwise always forced to be at |
2622 | C<st_nlink> field being zero (which is otherwise always forced to be at |
… | |
… | |
2842 | Apart from keeping your process non-blocking (which is a useful |
2852 | Apart from keeping your process non-blocking (which is a useful |
2843 | effect on its own sometimes), idle watchers are a good place to do |
2853 | effect on its own sometimes), idle watchers are a good place to do |
2844 | "pseudo-background processing", or delay processing stuff to after the |
2854 | "pseudo-background processing", or delay processing stuff to after the |
2845 | event loop has handled all outstanding events. |
2855 | event loop has handled all outstanding events. |
2846 | |
2856 | |
|
|
2857 | =head3 Abusing an C<ev_idle> watcher for its side-effect |
|
|
2858 | |
|
|
2859 | As long as there is at least one active idle watcher, libev will never |
|
|
2860 | sleep unnecessarily. Or in other words, it will loop as fast as possible. |
|
|
2861 | For this to work, the idle watcher doesn't need to be invoked at all - the |
|
|
2862 | lowest priority will do. |
|
|
2863 | |
|
|
2864 | This mode of operation can be useful together with an C<ev_check> watcher, |
|
|
2865 | to do something on each event loop iteration - for example to balance load |
|
|
2866 | between different connections. |
|
|
2867 | |
|
|
2868 | See L</Abusing an ev_check watcher for its side-effect> for a longer |
|
|
2869 | example. |
|
|
2870 | |
2847 | =head3 Watcher-Specific Functions and Data Members |
2871 | =head3 Watcher-Specific Functions and Data Members |
2848 | |
2872 | |
2849 | =over 4 |
2873 | =over 4 |
2850 | |
2874 | |
2851 | =item ev_idle_init (ev_idle *, callback) |
2875 | =item ev_idle_init (ev_idle *, callback) |
… | |
… | |
2862 | callback, free it. Also, use no error checking, as usual. |
2886 | callback, free it. Also, use no error checking, as usual. |
2863 | |
2887 | |
2864 | static void |
2888 | static void |
2865 | idle_cb (struct ev_loop *loop, ev_idle *w, int revents) |
2889 | idle_cb (struct ev_loop *loop, ev_idle *w, int revents) |
2866 | { |
2890 | { |
|
|
2891 | // stop the watcher |
|
|
2892 | ev_idle_stop (loop, w); |
|
|
2893 | |
|
|
2894 | // now we can free it |
2867 | free (w); |
2895 | free (w); |
|
|
2896 | |
2868 | // now do something you wanted to do when the program has |
2897 | // now do something you wanted to do when the program has |
2869 | // no longer anything immediate to do. |
2898 | // no longer anything immediate to do. |
2870 | } |
2899 | } |
2871 | |
2900 | |
2872 | ev_idle *idle_watcher = malloc (sizeof (ev_idle)); |
2901 | ev_idle *idle_watcher = malloc (sizeof (ev_idle)); |
… | |
… | |
2874 | ev_idle_start (loop, idle_watcher); |
2903 | ev_idle_start (loop, idle_watcher); |
2875 | |
2904 | |
2876 | |
2905 | |
2877 | =head2 C<ev_prepare> and C<ev_check> - customise your event loop! |
2906 | =head2 C<ev_prepare> and C<ev_check> - customise your event loop! |
2878 | |
2907 | |
2879 | Prepare and check watchers are usually (but not always) used in pairs: |
2908 | Prepare and check watchers are often (but not always) used in pairs: |
2880 | prepare watchers get invoked before the process blocks and check watchers |
2909 | prepare watchers get invoked before the process blocks and check watchers |
2881 | afterwards. |
2910 | afterwards. |
2882 | |
2911 | |
2883 | You I<must not> call C<ev_run> or similar functions that enter |
2912 | You I<must not> call C<ev_run> or similar functions that enter |
2884 | the current event loop from either C<ev_prepare> or C<ev_check> |
2913 | the current event loop from either C<ev_prepare> or C<ev_check> |
… | |
… | |
2912 | with priority higher than or equal to the event loop and one coroutine |
2941 | with priority higher than or equal to the event loop and one coroutine |
2913 | of lower priority, but only once, using idle watchers to keep the event |
2942 | of lower priority, but only once, using idle watchers to keep the event |
2914 | loop from blocking if lower-priority coroutines are active, thus mapping |
2943 | loop from blocking if lower-priority coroutines are active, thus mapping |
2915 | low-priority coroutines to idle/background tasks). |
2944 | low-priority coroutines to idle/background tasks). |
2916 | |
2945 | |
2917 | It is recommended to give C<ev_check> watchers highest (C<EV_MAXPRI>) |
2946 | When used for this purpose, it is recommended to give C<ev_check> watchers |
2918 | priority, to ensure that they are being run before any other watchers |
2947 | highest (C<EV_MAXPRI>) priority, to ensure that they are being run before |
2919 | after the poll (this doesn't matter for C<ev_prepare> watchers). |
2948 | any other watchers after the poll (this doesn't matter for C<ev_prepare> |
|
|
2949 | watchers). |
2920 | |
2950 | |
2921 | Also, C<ev_check> watchers (and C<ev_prepare> watchers, too) should not |
2951 | Also, C<ev_check> watchers (and C<ev_prepare> watchers, too) should not |
2922 | activate ("feed") events into libev. While libev fully supports this, they |
2952 | activate ("feed") events into libev. While libev fully supports this, they |
2923 | might get executed before other C<ev_check> watchers did their job. As |
2953 | might get executed before other C<ev_check> watchers did their job. As |
2924 | C<ev_check> watchers are often used to embed other (non-libev) event |
2954 | C<ev_check> watchers are often used to embed other (non-libev) event |
2925 | loops those other event loops might be in an unusable state until their |
2955 | loops those other event loops might be in an unusable state until their |
2926 | C<ev_check> watcher ran (always remind yourself to coexist peacefully with |
2956 | C<ev_check> watcher ran (always remind yourself to coexist peacefully with |
2927 | others). |
2957 | others). |
|
|
2958 | |
|
|
2959 | =head3 Abusing an C<ev_check> watcher for its side-effect |
|
|
2960 | |
|
|
2961 | C<ev_check> (and less often also C<ev_prepare>) watchers can also be |
|
|
2962 | useful because they are called once per event loop iteration. For |
|
|
2963 | example, if you want to handle a large number of connections fairly, you |
|
|
2964 | normally only do a bit of work for each active connection, and if there |
|
|
2965 | is more work to do, you wait for the next event loop iteration, so other |
|
|
2966 | connections have a chance of making progress. |
|
|
2967 | |
|
|
2968 | Using an C<ev_check> watcher is almost enough: it will be called on the |
|
|
2969 | next event loop iteration. However, that isn't as soon as possible - |
|
|
2970 | without external events, your C<ev_check> watcher will not be invoked. |
|
|
2971 | |
|
|
2972 | This is where C<ev_idle> watchers come in handy - all you need is a |
|
|
2973 | single global idle watcher that is active as long as you have one active |
|
|
2974 | C<ev_check> watcher. The C<ev_idle> watcher makes sure the event loop |
|
|
2975 | will not sleep, and the C<ev_check> watcher makes sure a callback gets |
|
|
2976 | invoked. Neither watcher alone can do that. |
2928 | |
2977 | |
2929 | =head3 Watcher-Specific Functions and Data Members |
2978 | =head3 Watcher-Specific Functions and Data Members |
2930 | |
2979 | |
2931 | =over 4 |
2980 | =over 4 |
2932 | |
2981 | |
… | |
… | |
3133 | |
3182 | |
3134 | =over 4 |
3183 | =over 4 |
3135 | |
3184 | |
3136 | =item ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop) |
3185 | =item ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop) |
3137 | |
3186 | |
3138 | =item ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop) |
3187 | =item ev_embed_set (ev_embed *, struct ev_loop *embedded_loop) |
3139 | |
3188 | |
3140 | Configures the watcher to embed the given loop, which must be |
3189 | Configures the watcher to embed the given loop, which must be |
3141 | embeddable. If the callback is C<0>, then C<ev_embed_sweep> will be |
3190 | embeddable. If the callback is C<0>, then C<ev_embed_sweep> will be |
3142 | invoked automatically, otherwise it is the responsibility of the callback |
3191 | invoked automatically, otherwise it is the responsibility of the callback |
3143 | to invoke it (it will continue to be called until the sweep has been done, |
3192 | to invoke it (it will continue to be called until the sweep has been done, |
… | |
… | |
3206 | |
3255 | |
3207 | =head2 C<ev_fork> - the audacity to resume the event loop after a fork |
3256 | =head2 C<ev_fork> - the audacity to resume the event loop after a fork |
3208 | |
3257 | |
3209 | Fork watchers are called when a C<fork ()> was detected (usually because |
3258 | Fork watchers are called when a C<fork ()> was detected (usually because |
3210 | whoever is a good citizen cared to tell libev about it by calling |
3259 | whoever is a good citizen cared to tell libev about it by calling |
3211 | C<ev_default_fork> or C<ev_loop_fork>). The invocation is done before the |
3260 | C<ev_loop_fork>). The invocation is done before the event loop blocks next |
3212 | event loop blocks next and before C<ev_check> watchers are being called, |
3261 | and before C<ev_check> watchers are being called, and only in the child |
3213 | and only in the child after the fork. If whoever good citizen calling |
3262 | after the fork. If whoever good citizen calling C<ev_default_fork> cheats |
3214 | C<ev_default_fork> cheats and calls it in the wrong process, the fork |
3263 | and calls it in the wrong process, the fork handlers will be invoked, too, |
3215 | handlers will be invoked, too, of course. |
3264 | of course. |
3216 | |
3265 | |
3217 | =head3 The special problem of life after fork - how is it possible? |
3266 | =head3 The special problem of life after fork - how is it possible? |
3218 | |
3267 | |
3219 | Most uses of C<fork()> consist of forking, then some simple calls to set |
3268 | Most uses of C<fork()> consist of forking, then some simple calls to set |
3220 | up/change the process environment, followed by a call to C<exec()>. This |
3269 | up/change the process environment, followed by a call to C<exec()>. This |
… | |
… | |
3313 | it by calling C<ev_async_send>, which is thread- and signal safe. |
3362 | it by calling C<ev_async_send>, which is thread- and signal safe. |
3314 | |
3363 | |
3315 | This functionality is very similar to C<ev_signal> watchers, as signals, |
3364 | This functionality is very similar to C<ev_signal> watchers, as signals, |
3316 | too, are asynchronous in nature, and signals, too, will be compressed |
3365 | too, are asynchronous in nature, and signals, too, will be compressed |
3317 | (i.e. the number of callback invocations may be less than the number of |
3366 | (i.e. the number of callback invocations may be less than the number of |
3318 | C<ev_async_sent> calls). In fact, you could use signal watchers as a kind |
3367 | C<ev_async_send> calls). In fact, you could use signal watchers as a kind |
3319 | of "global async watchers" by using a watcher on an otherwise unused |
3368 | of "global async watchers" by using a watcher on an otherwise unused |
3320 | signal, and C<ev_feed_signal> to signal this watcher from another thread, |
3369 | signal, and C<ev_feed_signal> to signal this watcher from another thread, |
3321 | even without knowing which loop owns the signal. |
3370 | even without knowing which loop owns the signal. |
3322 | |
3371 | |
3323 | =head3 Queueing |
3372 | =head3 Queueing |
… | |
… | |
3614 | already been invoked. |
3663 | already been invoked. |
3615 | |
3664 | |
3616 | A common way around all these issues is to make sure that |
3665 | A common way around all these issues is to make sure that |
3617 | C<start_new_request> I<always> returns before the callback is invoked. If |
3666 | C<start_new_request> I<always> returns before the callback is invoked. If |
3618 | C<start_new_request> immediately knows the result, it can artificially |
3667 | C<start_new_request> immediately knows the result, it can artificially |
3619 | delay invoking the callback by e.g. using a C<prepare> or C<idle> watcher |
3668 | delay invoking the callback by using a C<prepare> or C<idle> watcher for |
3620 | for example, or more sneakily, by reusing an existing (stopped) watcher |
3669 | example, or more sneakily, by reusing an existing (stopped) watcher and |
3621 | and pushing it into the pending queue: |
3670 | pushing it into the pending queue: |
3622 | |
3671 | |
3623 | ev_set_cb (watcher, callback); |
3672 | ev_set_cb (watcher, callback); |
3624 | ev_feed_event (EV_A_ watcher, 0); |
3673 | ev_feed_event (EV_A_ watcher, 0); |
3625 | |
3674 | |
3626 | This way, C<start_new_request> can safely return before the callback is |
3675 | This way, C<start_new_request> can safely return before the callback is |
… | |
… | |
3634 | |
3683 | |
3635 | This brings the problem of exiting - a callback might want to finish the |
3684 | This brings the problem of exiting - a callback might want to finish the |
3636 | main C<ev_run> call, but not the nested one (e.g. user clicked "Quit", but |
3685 | main C<ev_run> call, but not the nested one (e.g. user clicked "Quit", but |
3637 | a modal "Are you sure?" dialog is still waiting), or just the nested one |
3686 | a modal "Are you sure?" dialog is still waiting), or just the nested one |
3638 | and not the main one (e.g. user clocked "Ok" in a modal dialog), or some |
3687 | and not the main one (e.g. user clocked "Ok" in a modal dialog), or some |
3639 | other combination: In these cases, C<ev_break> will not work alone. |
3688 | other combination: In these cases, a simple C<ev_break> will not work. |
3640 | |
3689 | |
3641 | The solution is to maintain "break this loop" variable for each C<ev_run> |
3690 | The solution is to maintain "break this loop" variable for each C<ev_run> |
3642 | invocation, and use a loop around C<ev_run> until the condition is |
3691 | invocation, and use a loop around C<ev_run> until the condition is |
3643 | triggered, using C<EVRUN_ONCE>: |
3692 | triggered, using C<EVRUN_ONCE>: |
3644 | |
3693 | |
… | |
… | |
3830 | called): |
3879 | called): |
3831 | |
3880 | |
3832 | void |
3881 | void |
3833 | wait_for_event (ev_watcher *w) |
3882 | wait_for_event (ev_watcher *w) |
3834 | { |
3883 | { |
3835 | ev_cb_set (w) = current_coro; |
3884 | ev_set_cb (w, current_coro); |
3836 | switch_to (libev_coro); |
3885 | switch_to (libev_coro); |
3837 | } |
3886 | } |
3838 | |
3887 | |
3839 | That basically suspends the coroutine inside C<wait_for_event> and |
3888 | That basically suspends the coroutine inside C<wait_for_event> and |
3840 | continues the libev coroutine, which, when appropriate, switches back to |
3889 | continues the libev coroutine, which, when appropriate, switches back to |
… | |
… | |
3843 | You can do similar tricks if you have, say, threads with an event queue - |
3892 | You can do similar tricks if you have, say, threads with an event queue - |
3844 | instead of storing a coroutine, you store the queue object and instead of |
3893 | instead of storing a coroutine, you store the queue object and instead of |
3845 | switching to a coroutine, you push the watcher onto the queue and notify |
3894 | switching to a coroutine, you push the watcher onto the queue and notify |
3846 | any waiters. |
3895 | any waiters. |
3847 | |
3896 | |
3848 | To embed libev, see L<EMBEDDING>, but in short, it's easiest to create two |
3897 | To embed libev, see L</EMBEDDING>, but in short, it's easiest to create two |
3849 | files, F<my_ev.h> and F<my_ev.c> that include the respective libev files: |
3898 | files, F<my_ev.h> and F<my_ev.c> that include the respective libev files: |
3850 | |
3899 | |
3851 | // my_ev.h |
3900 | // my_ev.h |
3852 | #define EV_CB_DECLARE(type) struct my_coro *cb; |
3901 | #define EV_CB_DECLARE(type) struct my_coro *cb; |
3853 | #define EV_CB_INVOKE(watcher) switch_to ((watcher)->cb); |
3902 | #define EV_CB_INVOKE(watcher) switch_to ((watcher)->cb); |
… | |
… | |
3905 | libev sources can be compiled as C++. Therefore, code that uses the C API |
3954 | libev sources can be compiled as C++. Therefore, code that uses the C API |
3906 | will work fine. |
3955 | will work fine. |
3907 | |
3956 | |
3908 | Proper exception specifications might have to be added to callbacks passed |
3957 | Proper exception specifications might have to be added to callbacks passed |
3909 | to libev: exceptions may be thrown only from watcher callbacks, all |
3958 | to libev: exceptions may be thrown only from watcher callbacks, all |
3910 | other callbacks (allocator, syserr, loop acquire/release and periodioc |
3959 | other callbacks (allocator, syserr, loop acquire/release and periodic |
3911 | reschedule callbacks) must not throw exceptions, and might need a C<throw |
3960 | reschedule callbacks) must not throw exceptions, and might need a C<throw |
3912 | ()> specification. If you have code that needs to be compiled as both C |
3961 | ()> specification. If you have code that needs to be compiled as both C |
3913 | and C++ you can use the C<EV_THROW> macro for this: |
3962 | and C++ you can use the C<EV_THROW> macro for this: |
3914 | |
3963 | |
3915 | static void |
3964 | static void |
… | |
… | |
3935 | Libev comes with some simplistic wrapper classes for C++ that mainly allow |
3984 | Libev comes with some simplistic wrapper classes for C++ that mainly allow |
3936 | you to use some convenience methods to start/stop watchers and also change |
3985 | you to use some convenience methods to start/stop watchers and also change |
3937 | the callback model to a model using method callbacks on objects. |
3986 | the callback model to a model using method callbacks on objects. |
3938 | |
3987 | |
3939 | To use it, |
3988 | To use it, |
3940 | |
3989 | |
3941 | #include <ev++.h> |
3990 | #include <ev++.h> |
3942 | |
3991 | |
3943 | This automatically includes F<ev.h> and puts all of its definitions (many |
3992 | This automatically includes F<ev.h> and puts all of its definitions (many |
3944 | of them macros) into the global namespace. All C++ specific things are |
3993 | of them macros) into the global namespace. All C++ specific things are |
3945 | put into the C<ev> namespace. It should support all the same embedding |
3994 | put into the C<ev> namespace. It should support all the same embedding |
… | |
… | |
4076 | Associates a different C<struct ev_loop> with this watcher. You can only |
4125 | Associates a different C<struct ev_loop> with this watcher. You can only |
4077 | do this when the watcher is inactive (and not pending either). |
4126 | do this when the watcher is inactive (and not pending either). |
4078 | |
4127 | |
4079 | =item w->set ([arguments]) |
4128 | =item w->set ([arguments]) |
4080 | |
4129 | |
4081 | Basically the same as C<ev_TYPE_set>, with the same arguments. Either this |
4130 | Basically the same as C<ev_TYPE_set> (except for C<ev::embed> watchers>), |
4082 | method or a suitable start method must be called at least once. Unlike the |
4131 | with the same arguments. Either this method or a suitable start method |
4083 | C counterpart, an active watcher gets automatically stopped and restarted |
4132 | must be called at least once. Unlike the C counterpart, an active watcher |
4084 | when reconfiguring it with this method. |
4133 | gets automatically stopped and restarted when reconfiguring it with this |
|
|
4134 | method. |
|
|
4135 | |
|
|
4136 | For C<ev::embed> watchers this method is called C<set_embed>, to avoid |
|
|
4137 | clashing with the C<set (loop)> method. |
4085 | |
4138 | |
4086 | =item w->start () |
4139 | =item w->start () |
4087 | |
4140 | |
4088 | Starts the watcher. Note that there is no C<loop> argument, as the |
4141 | Starts the watcher. Note that there is no C<loop> argument, as the |
4089 | constructor already stores the event loop. |
4142 | constructor already stores the event loop. |
… | |
… | |
4192 | =item Lua |
4245 | =item Lua |
4193 | |
4246 | |
4194 | Brian Maher has written a partial interface to libev for lua (at the |
4247 | Brian Maher has written a partial interface to libev for lua (at the |
4195 | time of this writing, only C<ev_io> and C<ev_timer>), to be found at |
4248 | time of this writing, only C<ev_io> and C<ev_timer>), to be found at |
4196 | L<http://github.com/brimworks/lua-ev>. |
4249 | L<http://github.com/brimworks/lua-ev>. |
|
|
4250 | |
|
|
4251 | =item Javascript |
|
|
4252 | |
|
|
4253 | Node.js (L<http://nodejs.org>) uses libev as the underlying event library. |
|
|
4254 | |
|
|
4255 | =item Others |
|
|
4256 | |
|
|
4257 | There are others, and I stopped counting. |
4197 | |
4258 | |
4198 | =back |
4259 | =back |
4199 | |
4260 | |
4200 | |
4261 | |
4201 | =head1 MACRO MAGIC |
4262 | =head1 MACRO MAGIC |
… | |
… | |
4500 | |
4561 | |
4501 | If programs implement their own fd to handle mapping on win32, then this |
4562 | If programs implement their own fd to handle mapping on win32, then this |
4502 | macro can be used to override the C<close> function, useful to unregister |
4563 | macro can be used to override the C<close> function, useful to unregister |
4503 | file descriptors again. Note that the replacement function has to close |
4564 | file descriptors again. Note that the replacement function has to close |
4504 | the underlying OS handle. |
4565 | the underlying OS handle. |
|
|
4566 | |
|
|
4567 | =item EV_USE_WSASOCKET |
|
|
4568 | |
|
|
4569 | If defined to be C<1>, libev will use C<WSASocket> to create its internal |
|
|
4570 | communication socket, which works better in some environments. Otherwise, |
|
|
4571 | the normal C<socket> function will be used, which works better in other |
|
|
4572 | environments. |
4505 | |
4573 | |
4506 | =item EV_USE_POLL |
4574 | =item EV_USE_POLL |
4507 | |
4575 | |
4508 | If defined to be C<1>, libev will compile in support for the C<poll>(2) |
4576 | If defined to be C<1>, libev will compile in support for the C<poll>(2) |
4509 | backend. Otherwise it will be enabled on non-win32 platforms. It |
4577 | backend. Otherwise it will be enabled on non-win32 platforms. It |
… | |
… | |
4554 | different cpus (or different cpu cores). This reduces dependencies |
4622 | different cpus (or different cpu cores). This reduces dependencies |
4555 | and makes libev faster. |
4623 | and makes libev faster. |
4556 | |
4624 | |
4557 | =item EV_NO_THREADS |
4625 | =item EV_NO_THREADS |
4558 | |
4626 | |
4559 | If defined to be C<1>, libev will assume that it will never be called |
4627 | If defined to be C<1>, libev will assume that it will never be called from |
4560 | from different threads, which is a stronger assumption than C<EV_NO_SMP>, |
4628 | different threads (that includes signal handlers), which is a stronger |
4561 | above. This reduces dependencies and makes libev faster. |
4629 | assumption than C<EV_NO_SMP>, above. This reduces dependencies and makes |
|
|
4630 | libev faster. |
4562 | |
4631 | |
4563 | =item EV_ATOMIC_T |
4632 | =item EV_ATOMIC_T |
4564 | |
4633 | |
4565 | Libev requires an integer type (suitable for storing C<0> or C<1>) whose |
4634 | Libev requires an integer type (suitable for storing C<0> or C<1>) whose |
4566 | access is atomic and serialised with respect to other threads or signal |
4635 | access is atomic with respect to other threads or signal contexts. No |
4567 | contexts. No such type is easily found in the C language, so you can |
4636 | such type is easily found in the C language, so you can provide your own |
4568 | provide your own type that you know is safe for your purposes. It is used |
4637 | type that you know is safe for your purposes. It is used both for signal |
4569 | both for signal handler "locking" as well as for signal and thread safety |
4638 | handler "locking" as well as for signal and thread safety in C<ev_async> |
4570 | in C<ev_async> watchers. |
4639 | watchers. |
4571 | |
4640 | |
4572 | In the absence of this define, libev will use C<sig_atomic_t volatile> |
4641 | In the absence of this define, libev will use C<sig_atomic_t volatile> |
4573 | (from F<signal.h>), which is usually good enough on most platforms, |
4642 | (from F<signal.h>), which is usually good enough on most platforms. |
4574 | although strictly speaking using a type that also implies a memory fence |
|
|
4575 | is required. |
|
|
4576 | |
4643 | |
4577 | =item EV_H (h) |
4644 | =item EV_H (h) |
4578 | |
4645 | |
4579 | The name of the F<ev.h> header file used to include it. The default if |
4646 | The name of the F<ev.h> header file used to include it. The default if |
4580 | undefined is C<"ev.h"> in F<event.h>, F<ev.c> and F<ev++.h>. This can be |
4647 | undefined is C<"ev.h"> in F<event.h>, F<ev.c> and F<ev++.h>. This can be |
… | |
… | |
4948 | default loop and triggering an C<ev_async> watcher from the default loop |
5015 | default loop and triggering an C<ev_async> watcher from the default loop |
4949 | watcher callback into the event loop interested in the signal. |
5016 | watcher callback into the event loop interested in the signal. |
4950 | |
5017 | |
4951 | =back |
5018 | =back |
4952 | |
5019 | |
4953 | See also L<THREAD LOCKING EXAMPLE>. |
5020 | See also L</THREAD LOCKING EXAMPLE>. |
4954 | |
5021 | |
4955 | =head3 COROUTINES |
5022 | =head3 COROUTINES |
4956 | |
5023 | |
4957 | Libev is very accommodating to coroutines ("cooperative threads"): |
5024 | Libev is very accommodating to coroutines ("cooperative threads"): |
4958 | libev fully supports nesting calls to its functions from different |
5025 | libev fully supports nesting calls to its functions from different |
… | |
… | |
5249 | thread" or will block signals process-wide, both behaviours would |
5316 | thread" or will block signals process-wide, both behaviours would |
5250 | be compatible with libev. Interaction between C<sigprocmask> and |
5317 | be compatible with libev. Interaction between C<sigprocmask> and |
5251 | C<pthread_sigmask> could complicate things, however. |
5318 | C<pthread_sigmask> could complicate things, however. |
5252 | |
5319 | |
5253 | The most portable way to handle signals is to block signals in all threads |
5320 | The most portable way to handle signals is to block signals in all threads |
5254 | except the initial one, and run the default loop in the initial thread as |
5321 | except the initial one, and run the signal handling loop in the initial |
5255 | well. |
5322 | thread as well. |
5256 | |
5323 | |
5257 | =item C<long> must be large enough for common memory allocation sizes |
5324 | =item C<long> must be large enough for common memory allocation sizes |
5258 | |
5325 | |
5259 | To improve portability and simplify its API, libev uses C<long> internally |
5326 | To improve portability and simplify its API, libev uses C<long> internally |
5260 | instead of C<size_t> when allocating its data structures. On non-POSIX |
5327 | instead of C<size_t> when allocating its data structures. On non-POSIX |
… | |
… | |
5364 | =over 4 |
5431 | =over 4 |
5365 | |
5432 | |
5366 | =item C<EV_COMPAT3> backwards compatibility mechanism |
5433 | =item C<EV_COMPAT3> backwards compatibility mechanism |
5367 | |
5434 | |
5368 | The backward compatibility mechanism can be controlled by |
5435 | The backward compatibility mechanism can be controlled by |
5369 | C<EV_COMPAT3>. See L<PREPROCESSOR SYMBOLS/MACROS> in the L<EMBEDDING> |
5436 | C<EV_COMPAT3>. See L</"PREPROCESSOR SYMBOLS/MACROS"> in the L</EMBEDDING> |
5370 | section. |
5437 | section. |
5371 | |
5438 | |
5372 | =item C<ev_default_destroy> and C<ev_default_fork> have been removed |
5439 | =item C<ev_default_destroy> and C<ev_default_fork> have been removed |
5373 | |
5440 | |
5374 | These calls can be replaced easily by their C<ev_loop_xxx> counterparts: |
5441 | These calls can be replaced easily by their C<ev_loop_xxx> counterparts: |
… | |
… | |
5417 | =over 4 |
5484 | =over 4 |
5418 | |
5485 | |
5419 | =item active |
5486 | =item active |
5420 | |
5487 | |
5421 | A watcher is active as long as it has been started and not yet stopped. |
5488 | A watcher is active as long as it has been started and not yet stopped. |
5422 | See L<WATCHER STATES> for details. |
5489 | See L</WATCHER STATES> for details. |
5423 | |
5490 | |
5424 | =item application |
5491 | =item application |
5425 | |
5492 | |
5426 | In this document, an application is whatever is using libev. |
5493 | In this document, an application is whatever is using libev. |
5427 | |
5494 | |
… | |
… | |
5463 | watchers and events. |
5530 | watchers and events. |
5464 | |
5531 | |
5465 | =item pending |
5532 | =item pending |
5466 | |
5533 | |
5467 | A watcher is pending as soon as the corresponding event has been |
5534 | A watcher is pending as soon as the corresponding event has been |
5468 | detected. See L<WATCHER STATES> for details. |
5535 | detected. See L</WATCHER STATES> for details. |
5469 | |
5536 | |
5470 | =item real time |
5537 | =item real time |
5471 | |
5538 | |
5472 | The physical time that is observed. It is apparently strictly monotonic :) |
5539 | The physical time that is observed. It is apparently strictly monotonic :) |
5473 | |
5540 | |