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1 | =encoding utf-8 |
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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 |
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405 | cannot be done in a threadsafe way, but usually it works if no other |
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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 |
… | |
… | |
678 | If you need dynamically allocated loops it is better to use C<ev_loop_new> |
682 | If you need dynamically allocated loops it is better to use C<ev_loop_new> |
679 | and C<ev_loop_destroy>. |
683 | and C<ev_loop_destroy>. |
680 | |
684 | |
681 | =item ev_loop_fork (loop) |
685 | =item ev_loop_fork (loop) |
682 | |
686 | |
683 | This function sets a flag that causes subsequent C<ev_run> iterations to |
687 | This function sets a flag that causes subsequent C<ev_run> iterations |
684 | reinitialise the kernel state for backends that have one. Despite the |
688 | to reinitialise the kernel state for backends that have one. Despite |
685 | name, you can call it anytime, but it makes most sense after forking, in |
689 | the name, you can call it anytime you are allowed to start or stop |
686 | the child process. You I<must> call it (or use C<EVFLAG_FORKCHECK>) in the |
690 | watchers (except inside an C<ev_prepare> callback), but it makes most |
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691 | sense after forking, in the child process. You I<must> call it (or use |
687 | child before resuming or calling C<ev_run>. |
692 | C<EVFLAG_FORKCHECK>) in the child before resuming or calling C<ev_run>. |
688 | |
693 | |
689 | Again, you I<have> to call it on I<any> loop that you want to re-use after |
694 | 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 |
695 | 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 |
696 | because some kernel interfaces *cough* I<kqueue> *cough* do funny things |
692 | during fork. |
697 | during fork. |
693 | |
698 | |
694 | On the other hand, you only need to call this function in the child |
699 | On the other hand, you only need to call this function in the child |
… | |
… | |
764 | |
769 | |
765 | This function is rarely useful, but when some event callback runs for a |
770 | 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 |
771 | very long time without entering the event loop, updating libev's idea of |
767 | the current time is a good idea. |
772 | the current time is a good idea. |
768 | |
773 | |
769 | See also L<The special problem of time updates> in the C<ev_timer> section. |
774 | See also L</The special problem of time updates> in the C<ev_timer> section. |
770 | |
775 | |
771 | =item ev_suspend (loop) |
776 | =item ev_suspend (loop) |
772 | |
777 | |
773 | =item ev_resume (loop) |
778 | =item ev_resume (loop) |
774 | |
779 | |
… | |
… | |
1318 | |
1323 | |
1319 | =item callback ev_cb (ev_TYPE *watcher) |
1324 | =item callback ev_cb (ev_TYPE *watcher) |
1320 | |
1325 | |
1321 | Returns the callback currently set on the watcher. |
1326 | Returns the callback currently set on the watcher. |
1322 | |
1327 | |
1323 | =item ev_cb_set (ev_TYPE *watcher, callback) |
1328 | =item ev_set_cb (ev_TYPE *watcher, callback) |
1324 | |
1329 | |
1325 | Change the callback. You can change the callback at virtually any time |
1330 | Change the callback. You can change the callback at virtually any time |
1326 | (modulo threads). |
1331 | (modulo threads). |
1327 | |
1332 | |
1328 | =item ev_set_priority (ev_TYPE *watcher, int priority) |
1333 | =item ev_set_priority (ev_TYPE *watcher, int priority) |
… | |
… | |
1346 | or might not have been clamped to the valid range. |
1351 | or might not have been clamped to the valid range. |
1347 | |
1352 | |
1348 | The default priority used by watchers when no priority has been set is |
1353 | The default priority used by watchers when no priority has been set is |
1349 | always C<0>, which is supposed to not be too high and not be too low :). |
1354 | always C<0>, which is supposed to not be too high and not be too low :). |
1350 | |
1355 | |
1351 | See L<WATCHER PRIORITY MODELS>, below, for a more thorough treatment of |
1356 | See L</WATCHER PRIORITY MODELS>, below, for a more thorough treatment of |
1352 | priorities. |
1357 | priorities. |
1353 | |
1358 | |
1354 | =item ev_invoke (loop, ev_TYPE *watcher, int revents) |
1359 | =item ev_invoke (loop, ev_TYPE *watcher, int revents) |
1355 | |
1360 | |
1356 | Invoke the C<watcher> with the given C<loop> and C<revents>. Neither |
1361 | Invoke the C<watcher> with the given C<loop> and C<revents>. Neither |
… | |
… | |
1381 | See also C<ev_feed_fd_event> and C<ev_feed_signal_event> for related |
1386 | See also C<ev_feed_fd_event> and C<ev_feed_signal_event> for related |
1382 | functions that do not need a watcher. |
1387 | functions that do not need a watcher. |
1383 | |
1388 | |
1384 | =back |
1389 | =back |
1385 | |
1390 | |
1386 | See also the L<ASSOCIATING CUSTOM DATA WITH A WATCHER> and L<BUILDING YOUR |
1391 | See also the L</ASSOCIATING CUSTOM DATA WITH A WATCHER> and L</BUILDING YOUR |
1387 | OWN COMPOSITE WATCHERS> idioms. |
1392 | OWN COMPOSITE WATCHERS> idioms. |
1388 | |
1393 | |
1389 | =head2 WATCHER STATES |
1394 | =head2 WATCHER STATES |
1390 | |
1395 | |
1391 | There are various watcher states mentioned throughout this manual - |
1396 | There are various watcher states mentioned throughout this manual - |
… | |
… | |
1393 | transition between them will be described in more detail - and while these |
1398 | transition between them will be described in more detail - and while these |
1394 | rules might look complicated, they usually do "the right thing". |
1399 | rules might look complicated, they usually do "the right thing". |
1395 | |
1400 | |
1396 | =over 4 |
1401 | =over 4 |
1397 | |
1402 | |
1398 | =item initialiased |
1403 | =item initialised |
1399 | |
1404 | |
1400 | Before a watcher can be registered with the event loop it has to be |
1405 | Before a watcher can be registered with the event loop it has to be |
1401 | initialised. This can be done with a call to C<ev_TYPE_init>, or calls to |
1406 | initialised. This can be done with a call to C<ev_TYPE_init>, or calls to |
1402 | C<ev_init> followed by the watcher-specific C<ev_TYPE_set> function. |
1407 | C<ev_init> followed by the watcher-specific C<ev_TYPE_set> function. |
1403 | |
1408 | |
… | |
… | |
2024 | |
2029 | |
2025 | The relative timeouts are calculated relative to the C<ev_now ()> |
2030 | The relative timeouts are calculated relative to the C<ev_now ()> |
2026 | time. This is usually the right thing as this timestamp refers to the time |
2031 | time. This is usually the right thing as this timestamp refers to the time |
2027 | of the event triggering whatever timeout you are modifying/starting. If |
2032 | of the event triggering whatever timeout you are modifying/starting. If |
2028 | you suspect event processing to be delayed and you I<need> to base the |
2033 | you suspect event processing to be delayed and you I<need> to base the |
2029 | timeout on the current time, use something like this to adjust for this: |
2034 | timeout on the current time, use something like the following to adjust |
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|
2035 | for it: |
2030 | |
2036 | |
2031 | ev_timer_set (&timer, after + ev_now () - ev_time (), 0.); |
2037 | ev_timer_set (&timer, after + (ev_time () - ev_now ()), 0.); |
2032 | |
2038 | |
2033 | If the event loop is suspended for a long time, you can also force an |
2039 | If the event loop is suspended for a long time, you can also force an |
2034 | update of the time returned by C<ev_now ()> by calling C<ev_now_update |
2040 | update of the time returned by C<ev_now ()> by calling C<ev_now_update |
2035 | ()>. |
2041 | ()>, although that will push the event time of all outstanding events |
|
|
2042 | further into the future. |
2036 | |
2043 | |
2037 | =head3 The special problem of unsynchronised clocks |
2044 | =head3 The special problem of unsynchronised clocks |
2038 | |
2045 | |
2039 | Modern systems have a variety of clocks - libev itself uses the normal |
2046 | Modern systems have a variety of clocks - libev itself uses the normal |
2040 | "wall clock" clock and, if available, the monotonic clock (to avoid time |
2047 | "wall clock" clock and, if available, the monotonic clock (to avoid time |
… | |
… | |
2136 | =item If the timer is repeating, make the C<repeat> value the new timeout |
2143 | =item If the timer is repeating, make the C<repeat> value the new timeout |
2137 | and start the timer, if necessary. |
2144 | and start the timer, if necessary. |
2138 | |
2145 | |
2139 | =back |
2146 | =back |
2140 | |
2147 | |
2141 | This sounds a bit complicated, see L<Be smart about timeouts>, above, for a |
2148 | This sounds a bit complicated, see L</Be smart about timeouts>, above, for a |
2142 | usage example. |
2149 | usage example. |
2143 | |
2150 | |
2144 | =item ev_tstamp ev_timer_remaining (loop, ev_timer *) |
2151 | =item ev_tstamp ev_timer_remaining (loop, ev_timer *) |
2145 | |
2152 | |
2146 | Returns the remaining time until a timer fires. If the timer is active, |
2153 | Returns the remaining time until a timer fires. If the timer is active, |
… | |
… | |
2389 | |
2396 | |
2390 | ev_periodic hourly_tick; |
2397 | ev_periodic hourly_tick; |
2391 | ev_periodic_init (&hourly_tick, clock_cb, |
2398 | ev_periodic_init (&hourly_tick, clock_cb, |
2392 | fmod (ev_now (loop), 3600.), 3600., 0); |
2399 | fmod (ev_now (loop), 3600.), 3600., 0); |
2393 | ev_periodic_start (loop, &hourly_tick); |
2400 | ev_periodic_start (loop, &hourly_tick); |
2394 | |
2401 | |
2395 | |
2402 | |
2396 | =head2 C<ev_signal> - signal me when a signal gets signalled! |
2403 | =head2 C<ev_signal> - signal me when a signal gets signalled! |
2397 | |
2404 | |
2398 | Signal watchers will trigger an event when the process receives a specific |
2405 | Signal watchers will trigger an event when the process receives a specific |
2399 | signal one or more times. Even though signals are very asynchronous, libev |
2406 | signal one or more times. Even though signals are very asynchronous, libev |
… | |
… | |
2409 | only within the same loop, i.e. you can watch for C<SIGINT> in your |
2416 | only within the same loop, i.e. you can watch for C<SIGINT> in your |
2410 | default loop and for C<SIGIO> in another loop, but you cannot watch for |
2417 | default loop and for C<SIGIO> in another loop, but you cannot watch for |
2411 | C<SIGINT> in both the default loop and another loop at the same time. At |
2418 | C<SIGINT> in both the default loop and another loop at the same time. At |
2412 | the moment, C<SIGCHLD> is permanently tied to the default loop. |
2419 | the moment, C<SIGCHLD> is permanently tied to the default loop. |
2413 | |
2420 | |
2414 | When the first watcher gets started will libev actually register something |
2421 | Only after the first watcher for a signal is started will libev actually |
2415 | with the kernel (thus it coexists with your own signal handlers as long as |
2422 | register something with the kernel. It thus coexists with your own signal |
2416 | you don't register any with libev for the same signal). |
2423 | handlers as long as you don't register any with libev for the same signal. |
2417 | |
2424 | |
2418 | If possible and supported, libev will install its handlers with |
2425 | If possible and supported, libev will install its handlers with |
2419 | C<SA_RESTART> (or equivalent) behaviour enabled, so system calls should |
2426 | C<SA_RESTART> (or equivalent) behaviour enabled, so system calls should |
2420 | not be unduly interrupted. If you have a problem with system calls getting |
2427 | not be unduly interrupted. If you have a problem with system calls getting |
2421 | interrupted by signals you can block all signals in an C<ev_check> watcher |
2428 | interrupted by signals you can block all signals in an C<ev_check> watcher |
… | |
… | |
2606 | |
2613 | |
2607 | =head2 C<ev_stat> - did the file attributes just change? |
2614 | =head2 C<ev_stat> - did the file attributes just change? |
2608 | |
2615 | |
2609 | This watches a file system path for attribute changes. That is, it calls |
2616 | This watches a file system path for attribute changes. That is, it calls |
2610 | C<stat> on that path in regular intervals (or when the OS says it changed) |
2617 | C<stat> on that path in regular intervals (or when the OS says it changed) |
2611 | and sees if it changed compared to the last time, invoking the callback if |
2618 | and sees if it changed compared to the last time, invoking the callback |
2612 | it did. |
2619 | if it did. Starting the watcher C<stat>'s the file, so only changes that |
|
|
2620 | happen after the watcher has been started will be reported. |
2613 | |
2621 | |
2614 | The path does not need to exist: changing from "path exists" to "path does |
2622 | The path does not need to exist: changing from "path exists" to "path does |
2615 | not exist" is a status change like any other. The condition "path does not |
2623 | not exist" is a status change like any other. The condition "path does not |
2616 | exist" (or more correctly "path cannot be stat'ed") is signified by the |
2624 | exist" (or more correctly "path cannot be stat'ed") is signified by the |
2617 | C<st_nlink> field being zero (which is otherwise always forced to be at |
2625 | C<st_nlink> field being zero (which is otherwise always forced to be at |
… | |
… | |
2858 | |
2866 | |
2859 | This mode of operation can be useful together with an C<ev_check> watcher, |
2867 | 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 |
2868 | to do something on each event loop iteration - for example to balance load |
2861 | between different connections. |
2869 | between different connections. |
2862 | |
2870 | |
2863 | See L<Abusing an C<ev_check> watcher for its side-effect> for a longer |
2871 | See L</Abusing an ev_check watcher for its side-effect> for a longer |
2864 | example. |
2872 | example. |
2865 | |
2873 | |
2866 | =head3 Watcher-Specific Functions and Data Members |
2874 | =head3 Watcher-Specific Functions and Data Members |
2867 | |
2875 | |
2868 | =over 4 |
2876 | =over 4 |
… | |
… | |
2881 | callback, free it. Also, use no error checking, as usual. |
2889 | callback, free it. Also, use no error checking, as usual. |
2882 | |
2890 | |
2883 | static void |
2891 | static void |
2884 | idle_cb (struct ev_loop *loop, ev_idle *w, int revents) |
2892 | idle_cb (struct ev_loop *loop, ev_idle *w, int revents) |
2885 | { |
2893 | { |
|
|
2894 | // stop the watcher |
|
|
2895 | ev_idle_stop (loop, w); |
|
|
2896 | |
|
|
2897 | // now we can free it |
2886 | free (w); |
2898 | free (w); |
|
|
2899 | |
2887 | // now do something you wanted to do when the program has |
2900 | // now do something you wanted to do when the program has |
2888 | // no longer anything immediate to do. |
2901 | // no longer anything immediate to do. |
2889 | } |
2902 | } |
2890 | |
2903 | |
2891 | ev_idle *idle_watcher = malloc (sizeof (ev_idle)); |
2904 | ev_idle *idle_watcher = malloc (sizeof (ev_idle)); |
… | |
… | |
2897 | |
2910 | |
2898 | Prepare and check watchers are often (but not always) used in pairs: |
2911 | Prepare and check watchers are often (but not always) used in pairs: |
2899 | prepare watchers get invoked before the process blocks and check watchers |
2912 | prepare watchers get invoked before the process blocks and check watchers |
2900 | afterwards. |
2913 | afterwards. |
2901 | |
2914 | |
2902 | You I<must not> call C<ev_run> or similar functions that enter |
2915 | You I<must not> call C<ev_run> (or similar functions that enter the |
2903 | the current event loop from either C<ev_prepare> or C<ev_check> |
2916 | current event loop) or C<ev_loop_fork> from either C<ev_prepare> or |
2904 | watchers. Other loops than the current one are fine, however. The |
2917 | C<ev_check> watchers. Other loops than the current one are fine, |
2905 | rationale behind this is that you do not need to check for recursion in |
2918 | however. The rationale behind this is that you do not need to check |
2906 | those watchers, i.e. the sequence will always be C<ev_prepare>, blocking, |
2919 | for recursion in those watchers, i.e. the sequence will always be |
2907 | C<ev_check> so if you have one watcher of each kind they will always be |
2920 | C<ev_prepare>, blocking, C<ev_check> so if you have one watcher of each |
2908 | called in pairs bracketing the blocking call. |
2921 | kind they will always be called in pairs bracketing the blocking call. |
2909 | |
2922 | |
2910 | Their main purpose is to integrate other event mechanisms into libev and |
2923 | Their main purpose is to integrate other event mechanisms into libev and |
2911 | their use is somewhat advanced. They could be used, for example, to track |
2924 | their use is somewhat advanced. They could be used, for example, to track |
2912 | variable changes, implement your own watchers, integrate net-snmp or a |
2925 | variable changes, implement your own watchers, integrate net-snmp or a |
2913 | coroutine library and lots more. They are also occasionally useful if |
2926 | coroutine library and lots more. They are also occasionally useful if |
… | |
… | |
2957 | |
2970 | |
2958 | Using an C<ev_check> watcher is almost enough: it will be called on the |
2971 | Using an C<ev_check> watcher is almost enough: it will be called on the |
2959 | next event loop iteration. However, that isn't as soon as possible - |
2972 | next event loop iteration. However, that isn't as soon as possible - |
2960 | without external events, your C<ev_check> watcher will not be invoked. |
2973 | without external events, your C<ev_check> watcher will not be invoked. |
2961 | |
2974 | |
2962 | |
|
|
2963 | This is where C<ev_idle> watchers come in handy - all you need is a |
2975 | This is where C<ev_idle> watchers come in handy - all you need is a |
2964 | single global idle watcher that is active as long as you have one active |
2976 | single global idle watcher that is active as long as you have one active |
2965 | C<ev_check> watcher. The C<ev_idle> watcher makes sure the event loop |
2977 | C<ev_check> watcher. The C<ev_idle> watcher makes sure the event loop |
2966 | will not sleep, and the C<ev_check> watcher makes sure a callback gets |
2978 | will not sleep, and the C<ev_check> watcher makes sure a callback gets |
2967 | invoked. Neither watcher alone can do that. |
2979 | invoked. Neither watcher alone can do that. |
… | |
… | |
3173 | |
3185 | |
3174 | =over 4 |
3186 | =over 4 |
3175 | |
3187 | |
3176 | =item ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop) |
3188 | =item ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop) |
3177 | |
3189 | |
3178 | =item ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop) |
3190 | =item ev_embed_set (ev_embed *, struct ev_loop *embedded_loop) |
3179 | |
3191 | |
3180 | Configures the watcher to embed the given loop, which must be |
3192 | Configures the watcher to embed the given loop, which must be |
3181 | embeddable. If the callback is C<0>, then C<ev_embed_sweep> will be |
3193 | embeddable. If the callback is C<0>, then C<ev_embed_sweep> will be |
3182 | invoked automatically, otherwise it is the responsibility of the callback |
3194 | invoked automatically, otherwise it is the responsibility of the callback |
3183 | to invoke it (it will continue to be called until the sweep has been done, |
3195 | to invoke it (it will continue to be called until the sweep has been done, |
… | |
… | |
3204 | used). |
3216 | used). |
3205 | |
3217 | |
3206 | struct ev_loop *loop_hi = ev_default_init (0); |
3218 | struct ev_loop *loop_hi = ev_default_init (0); |
3207 | struct ev_loop *loop_lo = 0; |
3219 | struct ev_loop *loop_lo = 0; |
3208 | ev_embed embed; |
3220 | ev_embed embed; |
3209 | |
3221 | |
3210 | // see if there is a chance of getting one that works |
3222 | // see if there is a chance of getting one that works |
3211 | // (remember that a flags value of 0 means autodetection) |
3223 | // (remember that a flags value of 0 means autodetection) |
3212 | loop_lo = ev_embeddable_backends () & ev_recommended_backends () |
3224 | loop_lo = ev_embeddable_backends () & ev_recommended_backends () |
3213 | ? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ()) |
3225 | ? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ()) |
3214 | : 0; |
3226 | : 0; |
… | |
… | |
3228 | C<loop_socket>. (One might optionally use C<EVFLAG_NOENV>, too). |
3240 | C<loop_socket>. (One might optionally use C<EVFLAG_NOENV>, too). |
3229 | |
3241 | |
3230 | struct ev_loop *loop = ev_default_init (0); |
3242 | struct ev_loop *loop = ev_default_init (0); |
3231 | struct ev_loop *loop_socket = 0; |
3243 | struct ev_loop *loop_socket = 0; |
3232 | ev_embed embed; |
3244 | ev_embed embed; |
3233 | |
3245 | |
3234 | if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE) |
3246 | if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE) |
3235 | if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE)) |
3247 | if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE)) |
3236 | { |
3248 | { |
3237 | ev_embed_init (&embed, 0, loop_socket); |
3249 | ev_embed_init (&embed, 0, loop_socket); |
3238 | ev_embed_start (loop, &embed); |
3250 | ev_embed_start (loop, &embed); |
… | |
… | |
3246 | |
3258 | |
3247 | =head2 C<ev_fork> - the audacity to resume the event loop after a fork |
3259 | =head2 C<ev_fork> - the audacity to resume the event loop after a fork |
3248 | |
3260 | |
3249 | Fork watchers are called when a C<fork ()> was detected (usually because |
3261 | Fork watchers are called when a C<fork ()> was detected (usually because |
3250 | whoever is a good citizen cared to tell libev about it by calling |
3262 | whoever is a good citizen cared to tell libev about it by calling |
3251 | C<ev_default_fork> or C<ev_loop_fork>). The invocation is done before the |
3263 | C<ev_loop_fork>). The invocation is done before the event loop blocks next |
3252 | event loop blocks next and before C<ev_check> watchers are being called, |
3264 | and before C<ev_check> watchers are being called, and only in the child |
3253 | and only in the child after the fork. If whoever good citizen calling |
3265 | after the fork. If whoever good citizen calling C<ev_default_fork> cheats |
3254 | C<ev_default_fork> cheats and calls it in the wrong process, the fork |
3266 | and calls it in the wrong process, the fork handlers will be invoked, too, |
3255 | handlers will be invoked, too, of course. |
3267 | of course. |
3256 | |
3268 | |
3257 | =head3 The special problem of life after fork - how is it possible? |
3269 | =head3 The special problem of life after fork - how is it possible? |
3258 | |
3270 | |
3259 | Most uses of C<fork()> consist of forking, then some simple calls to set |
3271 | Most uses of C<fork ()> consist of forking, then some simple calls to set |
3260 | up/change the process environment, followed by a call to C<exec()>. This |
3272 | up/change the process environment, followed by a call to C<exec()>. This |
3261 | sequence should be handled by libev without any problems. |
3273 | sequence should be handled by libev without any problems. |
3262 | |
3274 | |
3263 | This changes when the application actually wants to do event handling |
3275 | This changes when the application actually wants to do event handling |
3264 | in the child, or both parent in child, in effect "continuing" after the |
3276 | in the child, or both parent in child, in effect "continuing" after the |
… | |
… | |
3654 | already been invoked. |
3666 | already been invoked. |
3655 | |
3667 | |
3656 | A common way around all these issues is to make sure that |
3668 | A common way around all these issues is to make sure that |
3657 | C<start_new_request> I<always> returns before the callback is invoked. If |
3669 | C<start_new_request> I<always> returns before the callback is invoked. If |
3658 | C<start_new_request> immediately knows the result, it can artificially |
3670 | C<start_new_request> immediately knows the result, it can artificially |
3659 | delay invoking the callback by e.g. using a C<prepare> or C<idle> watcher |
3671 | delay invoking the callback by using a C<prepare> or C<idle> watcher for |
3660 | for example, or more sneakily, by reusing an existing (stopped) watcher |
3672 | example, or more sneakily, by reusing an existing (stopped) watcher and |
3661 | and pushing it into the pending queue: |
3673 | pushing it into the pending queue: |
3662 | |
3674 | |
3663 | ev_set_cb (watcher, callback); |
3675 | ev_set_cb (watcher, callback); |
3664 | ev_feed_event (EV_A_ watcher, 0); |
3676 | ev_feed_event (EV_A_ watcher, 0); |
3665 | |
3677 | |
3666 | This way, C<start_new_request> can safely return before the callback is |
3678 | This way, C<start_new_request> can safely return before the callback is |
… | |
… | |
3674 | |
3686 | |
3675 | This brings the problem of exiting - a callback might want to finish the |
3687 | This brings the problem of exiting - a callback might want to finish the |
3676 | main C<ev_run> call, but not the nested one (e.g. user clicked "Quit", but |
3688 | main C<ev_run> call, but not the nested one (e.g. user clicked "Quit", but |
3677 | a modal "Are you sure?" dialog is still waiting), or just the nested one |
3689 | a modal "Are you sure?" dialog is still waiting), or just the nested one |
3678 | and not the main one (e.g. user clocked "Ok" in a modal dialog), or some |
3690 | and not the main one (e.g. user clocked "Ok" in a modal dialog), or some |
3679 | other combination: In these cases, C<ev_break> will not work alone. |
3691 | other combination: In these cases, a simple C<ev_break> will not work. |
3680 | |
3692 | |
3681 | The solution is to maintain "break this loop" variable for each C<ev_run> |
3693 | The solution is to maintain "break this loop" variable for each C<ev_run> |
3682 | invocation, and use a loop around C<ev_run> until the condition is |
3694 | invocation, and use a loop around C<ev_run> until the condition is |
3683 | triggered, using C<EVRUN_ONCE>: |
3695 | triggered, using C<EVRUN_ONCE>: |
3684 | |
3696 | |
… | |
… | |
3870 | called): |
3882 | called): |
3871 | |
3883 | |
3872 | void |
3884 | void |
3873 | wait_for_event (ev_watcher *w) |
3885 | wait_for_event (ev_watcher *w) |
3874 | { |
3886 | { |
3875 | ev_cb_set (w) = current_coro; |
3887 | ev_set_cb (w, current_coro); |
3876 | switch_to (libev_coro); |
3888 | switch_to (libev_coro); |
3877 | } |
3889 | } |
3878 | |
3890 | |
3879 | That basically suspends the coroutine inside C<wait_for_event> and |
3891 | That basically suspends the coroutine inside C<wait_for_event> and |
3880 | continues the libev coroutine, which, when appropriate, switches back to |
3892 | continues the libev coroutine, which, when appropriate, switches back to |
… | |
… | |
3883 | You can do similar tricks if you have, say, threads with an event queue - |
3895 | You can do similar tricks if you have, say, threads with an event queue - |
3884 | instead of storing a coroutine, you store the queue object and instead of |
3896 | instead of storing a coroutine, you store the queue object and instead of |
3885 | switching to a coroutine, you push the watcher onto the queue and notify |
3897 | switching to a coroutine, you push the watcher onto the queue and notify |
3886 | any waiters. |
3898 | any waiters. |
3887 | |
3899 | |
3888 | To embed libev, see L<EMBEDDING>, but in short, it's easiest to create two |
3900 | To embed libev, see L</EMBEDDING>, but in short, it's easiest to create two |
3889 | files, F<my_ev.h> and F<my_ev.c> that include the respective libev files: |
3901 | files, F<my_ev.h> and F<my_ev.c> that include the respective libev files: |
3890 | |
3902 | |
3891 | // my_ev.h |
3903 | // my_ev.h |
3892 | #define EV_CB_DECLARE(type) struct my_coro *cb; |
3904 | #define EV_CB_DECLARE(type) struct my_coro *cb; |
3893 | #define EV_CB_INVOKE(watcher) switch_to ((watcher)->cb); |
3905 | #define EV_CB_INVOKE(watcher) switch_to ((watcher)->cb); |
… | |
… | |
3945 | libev sources can be compiled as C++. Therefore, code that uses the C API |
3957 | libev sources can be compiled as C++. Therefore, code that uses the C API |
3946 | will work fine. |
3958 | will work fine. |
3947 | |
3959 | |
3948 | Proper exception specifications might have to be added to callbacks passed |
3960 | Proper exception specifications might have to be added to callbacks passed |
3949 | to libev: exceptions may be thrown only from watcher callbacks, all |
3961 | to libev: exceptions may be thrown only from watcher callbacks, all |
3950 | other callbacks (allocator, syserr, loop acquire/release and periodioc |
3962 | other callbacks (allocator, syserr, loop acquire/release and periodic |
3951 | reschedule callbacks) must not throw exceptions, and might need a C<throw |
3963 | reschedule callbacks) must not throw exceptions, and might need a C<throw |
3952 | ()> specification. If you have code that needs to be compiled as both C |
3964 | ()> specification. If you have code that needs to be compiled as both C |
3953 | and C++ you can use the C<EV_THROW> macro for this: |
3965 | and C++ you can use the C<EV_THROW> macro for this: |
3954 | |
3966 | |
3955 | static void |
3967 | static void |
… | |
… | |
3975 | Libev comes with some simplistic wrapper classes for C++ that mainly allow |
3987 | Libev comes with some simplistic wrapper classes for C++ that mainly allow |
3976 | you to use some convenience methods to start/stop watchers and also change |
3988 | you to use some convenience methods to start/stop watchers and also change |
3977 | the callback model to a model using method callbacks on objects. |
3989 | the callback model to a model using method callbacks on objects. |
3978 | |
3990 | |
3979 | To use it, |
3991 | To use it, |
3980 | |
3992 | |
3981 | #include <ev++.h> |
3993 | #include <ev++.h> |
3982 | |
3994 | |
3983 | This automatically includes F<ev.h> and puts all of its definitions (many |
3995 | This automatically includes F<ev.h> and puts all of its definitions (many |
3984 | of them macros) into the global namespace. All C++ specific things are |
3996 | of them macros) into the global namespace. All C++ specific things are |
3985 | put into the C<ev> namespace. It should support all the same embedding |
3997 | put into the C<ev> namespace. It should support all the same embedding |
… | |
… | |
4088 | void operator() (ev::io &w, int revents) |
4100 | void operator() (ev::io &w, int revents) |
4089 | { |
4101 | { |
4090 | ... |
4102 | ... |
4091 | } |
4103 | } |
4092 | } |
4104 | } |
4093 | |
4105 | |
4094 | myfunctor f; |
4106 | myfunctor f; |
4095 | |
4107 | |
4096 | ev::io w; |
4108 | ev::io w; |
4097 | w.set (&f); |
4109 | w.set (&f); |
4098 | |
4110 | |
… | |
… | |
4116 | Associates a different C<struct ev_loop> with this watcher. You can only |
4128 | Associates a different C<struct ev_loop> with this watcher. You can only |
4117 | do this when the watcher is inactive (and not pending either). |
4129 | do this when the watcher is inactive (and not pending either). |
4118 | |
4130 | |
4119 | =item w->set ([arguments]) |
4131 | =item w->set ([arguments]) |
4120 | |
4132 | |
4121 | Basically the same as C<ev_TYPE_set>, with the same arguments. Either this |
4133 | Basically the same as C<ev_TYPE_set> (except for C<ev::embed> watchers>), |
4122 | method or a suitable start method must be called at least once. Unlike the |
4134 | with the same arguments. Either this method or a suitable start method |
4123 | C counterpart, an active watcher gets automatically stopped and restarted |
4135 | must be called at least once. Unlike the C counterpart, an active watcher |
4124 | when reconfiguring it with this method. |
4136 | gets automatically stopped and restarted when reconfiguring it with this |
|
|
4137 | method. |
|
|
4138 | |
|
|
4139 | For C<ev::embed> watchers this method is called C<set_embed>, to avoid |
|
|
4140 | clashing with the C<set (loop)> method. |
4125 | |
4141 | |
4126 | =item w->start () |
4142 | =item w->start () |
4127 | |
4143 | |
4128 | Starts the watcher. Note that there is no C<loop> argument, as the |
4144 | Starts the watcher. Note that there is no C<loop> argument, as the |
4129 | constructor already stores the event loop. |
4145 | constructor already stores the event loop. |
… | |
… | |
4232 | =item Lua |
4248 | =item Lua |
4233 | |
4249 | |
4234 | Brian Maher has written a partial interface to libev for lua (at the |
4250 | Brian Maher has written a partial interface to libev for lua (at the |
4235 | time of this writing, only C<ev_io> and C<ev_timer>), to be found at |
4251 | time of this writing, only C<ev_io> and C<ev_timer>), to be found at |
4236 | L<http://github.com/brimworks/lua-ev>. |
4252 | L<http://github.com/brimworks/lua-ev>. |
|
|
4253 | |
|
|
4254 | =item Javascript |
|
|
4255 | |
|
|
4256 | Node.js (L<http://nodejs.org>) uses libev as the underlying event library. |
|
|
4257 | |
|
|
4258 | =item Others |
|
|
4259 | |
|
|
4260 | There are others, and I stopped counting. |
4237 | |
4261 | |
4238 | =back |
4262 | =back |
4239 | |
4263 | |
4240 | |
4264 | |
4241 | =head1 MACRO MAGIC |
4265 | =head1 MACRO MAGIC |
… | |
… | |
4540 | |
4564 | |
4541 | If programs implement their own fd to handle mapping on win32, then this |
4565 | If programs implement their own fd to handle mapping on win32, then this |
4542 | macro can be used to override the C<close> function, useful to unregister |
4566 | macro can be used to override the C<close> function, useful to unregister |
4543 | file descriptors again. Note that the replacement function has to close |
4567 | file descriptors again. Note that the replacement function has to close |
4544 | the underlying OS handle. |
4568 | the underlying OS handle. |
|
|
4569 | |
|
|
4570 | =item EV_USE_WSASOCKET |
|
|
4571 | |
|
|
4572 | If defined to be C<1>, libev will use C<WSASocket> to create its internal |
|
|
4573 | communication socket, which works better in some environments. Otherwise, |
|
|
4574 | the normal C<socket> function will be used, which works better in other |
|
|
4575 | environments. |
4545 | |
4576 | |
4546 | =item EV_USE_POLL |
4577 | =item EV_USE_POLL |
4547 | |
4578 | |
4548 | If defined to be C<1>, libev will compile in support for the C<poll>(2) |
4579 | If defined to be C<1>, libev will compile in support for the C<poll>(2) |
4549 | backend. Otherwise it will be enabled on non-win32 platforms. It |
4580 | backend. Otherwise it will be enabled on non-win32 platforms. It |
… | |
… | |
4594 | different cpus (or different cpu cores). This reduces dependencies |
4625 | different cpus (or different cpu cores). This reduces dependencies |
4595 | and makes libev faster. |
4626 | and makes libev faster. |
4596 | |
4627 | |
4597 | =item EV_NO_THREADS |
4628 | =item EV_NO_THREADS |
4598 | |
4629 | |
4599 | If defined to be C<1>, libev will assume that it will never be called |
4630 | If defined to be C<1>, libev will assume that it will never be called from |
4600 | from different threads, which is a stronger assumption than C<EV_NO_SMP>, |
4631 | different threads (that includes signal handlers), which is a stronger |
4601 | above. This reduces dependencies and makes libev faster. |
4632 | assumption than C<EV_NO_SMP>, above. This reduces dependencies and makes |
|
|
4633 | libev faster. |
4602 | |
4634 | |
4603 | =item EV_ATOMIC_T |
4635 | =item EV_ATOMIC_T |
4604 | |
4636 | |
4605 | Libev requires an integer type (suitable for storing C<0> or C<1>) whose |
4637 | Libev requires an integer type (suitable for storing C<0> or C<1>) whose |
4606 | access is atomic and serialised with respect to other threads or signal |
4638 | access is atomic with respect to other threads or signal contexts. No |
4607 | contexts. No such type is easily found in the C language, so you can |
4639 | such type is easily found in the C language, so you can provide your own |
4608 | provide your own type that you know is safe for your purposes. It is used |
4640 | type that you know is safe for your purposes. It is used both for signal |
4609 | both for signal handler "locking" as well as for signal and thread safety |
4641 | handler "locking" as well as for signal and thread safety in C<ev_async> |
4610 | in C<ev_async> watchers. |
4642 | watchers. |
4611 | |
4643 | |
4612 | In the absence of this define, libev will use C<sig_atomic_t volatile> |
4644 | In the absence of this define, libev will use C<sig_atomic_t volatile> |
4613 | (from F<signal.h>), which is usually good enough on most platforms, |
4645 | (from F<signal.h>), which is usually good enough on most platforms. |
4614 | although strictly speaking using a type that also implies a memory fence |
|
|
4615 | is required. |
|
|
4616 | |
4646 | |
4617 | =item EV_H (h) |
4647 | =item EV_H (h) |
4618 | |
4648 | |
4619 | The name of the F<ev.h> header file used to include it. The default if |
4649 | The name of the F<ev.h> header file used to include it. The default if |
4620 | undefined is C<"ev.h"> in F<event.h>, F<ev.c> and F<ev++.h>. This can be |
4650 | undefined is C<"ev.h"> in F<event.h>, F<ev.c> and F<ev++.h>. This can be |
… | |
… | |
4988 | default loop and triggering an C<ev_async> watcher from the default loop |
5018 | default loop and triggering an C<ev_async> watcher from the default loop |
4989 | watcher callback into the event loop interested in the signal. |
5019 | watcher callback into the event loop interested in the signal. |
4990 | |
5020 | |
4991 | =back |
5021 | =back |
4992 | |
5022 | |
4993 | See also L<THREAD LOCKING EXAMPLE>. |
5023 | See also L</THREAD LOCKING EXAMPLE>. |
4994 | |
5024 | |
4995 | =head3 COROUTINES |
5025 | =head3 COROUTINES |
4996 | |
5026 | |
4997 | Libev is very accommodating to coroutines ("cooperative threads"): |
5027 | Libev is very accommodating to coroutines ("cooperative threads"): |
4998 | libev fully supports nesting calls to its functions from different |
5028 | libev fully supports nesting calls to its functions from different |
… | |
… | |
5289 | thread" or will block signals process-wide, both behaviours would |
5319 | thread" or will block signals process-wide, both behaviours would |
5290 | be compatible with libev. Interaction between C<sigprocmask> and |
5320 | be compatible with libev. Interaction between C<sigprocmask> and |
5291 | C<pthread_sigmask> could complicate things, however. |
5321 | C<pthread_sigmask> could complicate things, however. |
5292 | |
5322 | |
5293 | The most portable way to handle signals is to block signals in all threads |
5323 | The most portable way to handle signals is to block signals in all threads |
5294 | except the initial one, and run the default loop in the initial thread as |
5324 | except the initial one, and run the signal handling loop in the initial |
5295 | well. |
5325 | thread as well. |
5296 | |
5326 | |
5297 | =item C<long> must be large enough for common memory allocation sizes |
5327 | =item C<long> must be large enough for common memory allocation sizes |
5298 | |
5328 | |
5299 | To improve portability and simplify its API, libev uses C<long> internally |
5329 | To improve portability and simplify its API, libev uses C<long> internally |
5300 | instead of C<size_t> when allocating its data structures. On non-POSIX |
5330 | instead of C<size_t> when allocating its data structures. On non-POSIX |
… | |
… | |
5404 | =over 4 |
5434 | =over 4 |
5405 | |
5435 | |
5406 | =item C<EV_COMPAT3> backwards compatibility mechanism |
5436 | =item C<EV_COMPAT3> backwards compatibility mechanism |
5407 | |
5437 | |
5408 | The backward compatibility mechanism can be controlled by |
5438 | The backward compatibility mechanism can be controlled by |
5409 | C<EV_COMPAT3>. See L<PREPROCESSOR SYMBOLS/MACROS> in the L<EMBEDDING> |
5439 | C<EV_COMPAT3>. See L</"PREPROCESSOR SYMBOLS/MACROS"> in the L</EMBEDDING> |
5410 | section. |
5440 | section. |
5411 | |
5441 | |
5412 | =item C<ev_default_destroy> and C<ev_default_fork> have been removed |
5442 | =item C<ev_default_destroy> and C<ev_default_fork> have been removed |
5413 | |
5443 | |
5414 | These calls can be replaced easily by their C<ev_loop_xxx> counterparts: |
5444 | These calls can be replaced easily by their C<ev_loop_xxx> counterparts: |
… | |
… | |
5457 | =over 4 |
5487 | =over 4 |
5458 | |
5488 | |
5459 | =item active |
5489 | =item active |
5460 | |
5490 | |
5461 | A watcher is active as long as it has been started and not yet stopped. |
5491 | A watcher is active as long as it has been started and not yet stopped. |
5462 | See L<WATCHER STATES> for details. |
5492 | See L</WATCHER STATES> for details. |
5463 | |
5493 | |
5464 | =item application |
5494 | =item application |
5465 | |
5495 | |
5466 | In this document, an application is whatever is using libev. |
5496 | In this document, an application is whatever is using libev. |
5467 | |
5497 | |
… | |
… | |
5503 | watchers and events. |
5533 | watchers and events. |
5504 | |
5534 | |
5505 | =item pending |
5535 | =item pending |
5506 | |
5536 | |
5507 | A watcher is pending as soon as the corresponding event has been |
5537 | A watcher is pending as soon as the corresponding event has been |
5508 | detected. See L<WATCHER STATES> for details. |
5538 | detected. See L</WATCHER STATES> for details. |
5509 | |
5539 | |
5510 | =item real time |
5540 | =item real time |
5511 | |
5541 | |
5512 | The physical time that is observed. It is apparently strictly monotonic :) |
5542 | The physical time that is observed. It is apparently strictly monotonic :) |
5513 | |
5543 | |