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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 |
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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 |
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247 | the current system, you would need to look at C<ev_embeddable_backends () |
249 | the current system, you would need to look at C<ev_embeddable_backends () |
248 | & ev_supported_backends ()>, likewise for recommended ones. |
250 | & ev_supported_backends ()>, likewise for recommended ones. |
249 | |
251 | |
250 | See the description of C<ev_embed> watchers for more info. |
252 | See the description of C<ev_embed> watchers for more info. |
251 | |
253 | |
252 | =item ev_set_allocator (void *(*cb)(void *ptr, long size)) |
254 | =item ev_set_allocator (void *(*cb)(void *ptr, long size) throw ()) |
253 | |
255 | |
254 | Sets the allocation function to use (the prototype is similar - the |
256 | Sets the allocation function to use (the prototype is similar - the |
255 | semantics are identical to the C<realloc> C89/SuS/POSIX function). It is |
257 | semantics are identical to the C<realloc> C89/SuS/POSIX function). It is |
256 | used to allocate and free memory (no surprises here). If it returns zero |
258 | used to allocate and free memory (no surprises here). If it returns zero |
257 | when memory needs to be allocated (C<size != 0>), the library might abort |
259 | when memory needs to be allocated (C<size != 0>), the library might abort |
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283 | } |
285 | } |
284 | |
286 | |
285 | ... |
287 | ... |
286 | ev_set_allocator (persistent_realloc); |
288 | ev_set_allocator (persistent_realloc); |
287 | |
289 | |
288 | =item ev_set_syserr_cb (void (*cb)(const char *msg)) |
290 | =item ev_set_syserr_cb (void (*cb)(const char *msg) throw ()) |
289 | |
291 | |
290 | Set the callback function to call on a retryable system call error (such |
292 | Set the callback function to call on a retryable system call error (such |
291 | as failed select, poll, epoll_wait). The message is a printable string |
293 | as failed select, poll, epoll_wait). The message is a printable string |
292 | indicating the system call or subsystem causing the problem. If this |
294 | indicating the system call or subsystem causing the problem. If this |
293 | callback is set, then libev will expect it to remedy the situation, no |
295 | callback is set, then libev will expect it to remedy the situation, no |
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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. |
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567 | |
571 | |
568 | It scales in the same way as the epoll backend, but the interface to the |
572 | It scales in the same way as the epoll backend, but the interface to the |
569 | kernel is more efficient (which says nothing about its actual speed, of |
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 (but |
576 | two event changes per incident. Support for C<fork ()> is very bad (you |
573 | sane, unlike epoll) and it drops fds silently in similarly hard-to-detect |
577 | might have to leak fd's on fork, but it's more sane than epoll) and it |
574 | 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 |
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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 |
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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 | |
… | |
… | |
792 | without a previous call to C<ev_suspend>. |
797 | without a previous call to C<ev_suspend>. |
793 | |
798 | |
794 | Calling C<ev_suspend>/C<ev_resume> has the side effect of updating the |
799 | Calling C<ev_suspend>/C<ev_resume> has the side effect of updating the |
795 | event loop time (see C<ev_now_update>). |
800 | event loop time (see C<ev_now_update>). |
796 | |
801 | |
797 | =item ev_run (loop, int flags) |
802 | =item bool ev_run (loop, int flags) |
798 | |
803 | |
799 | Finally, this is it, the event handler. This function usually is called |
804 | Finally, this is it, the event handler. This function usually is called |
800 | after you have initialised all your watchers and you want to start |
805 | after you have initialised all your watchers and you want to start |
801 | handling events. It will ask the operating system for any new events, call |
806 | handling events. It will ask the operating system for any new events, call |
802 | the watcher callbacks, an then repeat the whole process indefinitely: This |
807 | the watcher callbacks, and then repeat the whole process indefinitely: This |
803 | is why event loops are called I<loops>. |
808 | is why event loops are called I<loops>. |
804 | |
809 | |
805 | If the flags argument is specified as C<0>, it will keep handling events |
810 | If the flags argument is specified as C<0>, it will keep handling events |
806 | until either no event watchers are active anymore or C<ev_break> was |
811 | until either no event watchers are active anymore or C<ev_break> was |
807 | called. |
812 | called. |
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813 | |
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814 | The return value is false if there are no more active watchers (which |
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815 | usually means "all jobs done" or "deadlock"), and true in all other cases |
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816 | (which usually means " you should call C<ev_run> again"). |
808 | |
817 | |
809 | Please note that an explicit C<ev_break> is usually better than |
818 | Please note that an explicit C<ev_break> is usually better than |
810 | relying on all watchers to be stopped when deciding when a program has |
819 | relying on all watchers to be stopped when deciding when a program has |
811 | finished (especially in interactive programs), but having a program |
820 | finished (especially in interactive programs), but having a program |
812 | that automatically loops as long as it has to and no longer by virtue |
821 | that automatically loops as long as it has to and no longer by virtue |
813 | of relying on its watchers stopping correctly, that is truly a thing of |
822 | of relying on its watchers stopping correctly, that is truly a thing of |
814 | beauty. |
823 | beauty. |
815 | |
824 | |
816 | This function is also I<mostly> exception-safe - you can break out of |
825 | This function is I<mostly> exception-safe - you can break out of a |
817 | a C<ev_run> call by calling C<longjmp> in a callback, throwing a C++ |
826 | C<ev_run> call by calling C<longjmp> in a callback, throwing a C++ |
818 | exception and so on. This does not decrement the C<ev_depth> value, nor |
827 | exception and so on. This does not decrement the C<ev_depth> value, nor |
819 | will it clear any outstanding C<EVBREAK_ONE> breaks. |
828 | will it clear any outstanding C<EVBREAK_ONE> breaks. |
820 | |
829 | |
821 | A flags value of C<EVRUN_NOWAIT> will look for new events, will handle |
830 | A flags value of C<EVRUN_NOWAIT> will look for new events, will handle |
822 | those events and any already outstanding ones, but will not wait and |
831 | those events and any already outstanding ones, but will not wait and |
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1012 | invoke the actual watchers inside another context (another thread etc.). |
1021 | invoke the actual watchers inside another context (another thread etc.). |
1013 | |
1022 | |
1014 | If you want to reset the callback, use C<ev_invoke_pending> as new |
1023 | If you want to reset the callback, use C<ev_invoke_pending> as new |
1015 | callback. |
1024 | callback. |
1016 | |
1025 | |
1017 | =item ev_set_loop_release_cb (loop, void (*release)(EV_P), void (*acquire)(EV_P)) |
1026 | =item ev_set_loop_release_cb (loop, void (*release)(EV_P) throw (), void (*acquire)(EV_P) throw ()) |
1018 | |
1027 | |
1019 | Sometimes you want to share the same loop between multiple threads. This |
1028 | Sometimes you want to share the same loop between multiple threads. This |
1020 | can be done relatively simply by putting mutex_lock/unlock calls around |
1029 | can be done relatively simply by putting mutex_lock/unlock calls around |
1021 | each call to a libev function. |
1030 | each call to a libev function. |
1022 | |
1031 | |
… | |
… | |
1170 | |
1179 | |
1171 | =item C<EV_PREPARE> |
1180 | =item C<EV_PREPARE> |
1172 | |
1181 | |
1173 | =item C<EV_CHECK> |
1182 | =item C<EV_CHECK> |
1174 | |
1183 | |
1175 | All C<ev_prepare> watchers are invoked just I<before> C<ev_run> starts |
1184 | All C<ev_prepare> watchers are invoked just I<before> C<ev_run> starts to |
1176 | to gather new events, and all C<ev_check> watchers are invoked just after |
1185 | gather new events, and all C<ev_check> watchers are queued (not invoked) |
1177 | C<ev_run> has gathered them, but before it invokes any callbacks for any |
1186 | just after C<ev_run> has gathered them, but before it queues any callbacks |
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1187 | for any received events. That means C<ev_prepare> watchers are the last |
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1188 | watchers invoked before the event loop sleeps or polls for new events, and |
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1189 | C<ev_check> watchers will be invoked before any other watchers of the same |
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1190 | or lower priority within an event loop iteration. |
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1191 | |
1178 | received events. Callbacks of both watcher types can start and stop as |
1192 | Callbacks of both watcher types can start and stop as many watchers as |
1179 | many watchers as they want, and all of them will be taken into account |
1193 | they want, and all of them will be taken into account (for example, a |
1180 | (for example, a C<ev_prepare> watcher might start an idle watcher to keep |
1194 | C<ev_prepare> watcher might start an idle watcher to keep C<ev_run> from |
1181 | C<ev_run> from blocking). |
1195 | blocking). |
1182 | |
1196 | |
1183 | =item C<EV_EMBED> |
1197 | =item C<EV_EMBED> |
1184 | |
1198 | |
1185 | The embedded event loop specified in the C<ev_embed> watcher needs attention. |
1199 | The embedded event loop specified in the C<ev_embed> watcher needs attention. |
1186 | |
1200 | |
… | |
… | |
1309 | |
1323 | |
1310 | =item callback ev_cb (ev_TYPE *watcher) |
1324 | =item callback ev_cb (ev_TYPE *watcher) |
1311 | |
1325 | |
1312 | Returns the callback currently set on the watcher. |
1326 | Returns the callback currently set on the watcher. |
1313 | |
1327 | |
1314 | =item ev_cb_set (ev_TYPE *watcher, callback) |
1328 | =item ev_set_cb (ev_TYPE *watcher, callback) |
1315 | |
1329 | |
1316 | 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 |
1317 | (modulo threads). |
1331 | (modulo threads). |
1318 | |
1332 | |
1319 | =item ev_set_priority (ev_TYPE *watcher, int priority) |
1333 | =item ev_set_priority (ev_TYPE *watcher, int priority) |
… | |
… | |
1337 | or might not have been clamped to the valid range. |
1351 | or might not have been clamped to the valid range. |
1338 | |
1352 | |
1339 | 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 |
1340 | 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 :). |
1341 | |
1355 | |
1342 | 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 |
1343 | priorities. |
1357 | priorities. |
1344 | |
1358 | |
1345 | =item ev_invoke (loop, ev_TYPE *watcher, int revents) |
1359 | =item ev_invoke (loop, ev_TYPE *watcher, int revents) |
1346 | |
1360 | |
1347 | 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 |
… | |
… | |
1372 | 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 |
1373 | functions that do not need a watcher. |
1387 | functions that do not need a watcher. |
1374 | |
1388 | |
1375 | =back |
1389 | =back |
1376 | |
1390 | |
1377 | 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 |
1378 | OWN COMPOSITE WATCHERS> idioms. |
1392 | OWN COMPOSITE WATCHERS> idioms. |
1379 | |
1393 | |
1380 | =head2 WATCHER STATES |
1394 | =head2 WATCHER STATES |
1381 | |
1395 | |
1382 | There are various watcher states mentioned throughout this manual - |
1396 | There are various watcher states mentioned throughout this manual - |
… | |
… | |
1384 | 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 |
1385 | rules might look complicated, they usually do "the right thing". |
1399 | rules might look complicated, they usually do "the right thing". |
1386 | |
1400 | |
1387 | =over 4 |
1401 | =over 4 |
1388 | |
1402 | |
1389 | =item initialiased |
1403 | =item initialised |
1390 | |
1404 | |
1391 | 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 |
1392 | 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 |
1393 | 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. |
1394 | |
1408 | |
… | |
… | |
1870 | callback (EV_P_ ev_timer *w, int revents) |
1884 | callback (EV_P_ ev_timer *w, int revents) |
1871 | { |
1885 | { |
1872 | // calculate when the timeout would happen |
1886 | // calculate when the timeout would happen |
1873 | ev_tstamp after = last_activity - ev_now (EV_A) + timeout; |
1887 | ev_tstamp after = last_activity - ev_now (EV_A) + timeout; |
1874 | |
1888 | |
1875 | // if negative, it means we the timeout already occured |
1889 | // if negative, it means we the timeout already occurred |
1876 | if (after < 0.) |
1890 | if (after < 0.) |
1877 | { |
1891 | { |
1878 | // timeout occurred, take action |
1892 | // timeout occurred, take action |
1879 | } |
1893 | } |
1880 | else |
1894 | else |
… | |
… | |
1898 | |
1912 | |
1899 | Otherwise, we now the earliest time at which the timeout would trigger, |
1913 | Otherwise, we now the earliest time at which the timeout would trigger, |
1900 | and simply start the timer with this timeout value. |
1914 | and simply start the timer with this timeout value. |
1901 | |
1915 | |
1902 | In other words, each time the callback is invoked it will check whether |
1916 | In other words, each time the callback is invoked it will check whether |
1903 | the timeout cocured. If not, it will simply reschedule itself to check |
1917 | the timeout occurred. If not, it will simply reschedule itself to check |
1904 | again at the earliest time it could time out. Rinse. Repeat. |
1918 | again at the earliest time it could time out. Rinse. Repeat. |
1905 | |
1919 | |
1906 | This scheme causes more callback invocations (about one every 60 seconds |
1920 | This scheme causes more callback invocations (about one every 60 seconds |
1907 | minus half the average time between activity), but virtually no calls to |
1921 | minus half the average time between activity), but virtually no calls to |
1908 | libev to change the timeout. |
1922 | libev to change the timeout. |
… | |
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1922 | if (activity detected) |
1936 | if (activity detected) |
1923 | last_activity = ev_now (EV_A); |
1937 | last_activity = ev_now (EV_A); |
1924 | |
1938 | |
1925 | When your timeout value changes, then the timeout can be changed by simply |
1939 | When your timeout value changes, then the timeout can be changed by simply |
1926 | providing a new value, stopping the timer and calling the callback, which |
1940 | providing a new value, stopping the timer and calling the callback, which |
1927 | will agaion do the right thing (for example, time out immediately :). |
1941 | will again do the right thing (for example, time out immediately :). |
1928 | |
1942 | |
1929 | timeout = new_value; |
1943 | timeout = new_value; |
1930 | ev_timer_stop (EV_A_ &timer); |
1944 | ev_timer_stop (EV_A_ &timer); |
1931 | callback (EV_A_ &timer, 0); |
1945 | callback (EV_A_ &timer, 0); |
1932 | |
1946 | |
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2108 | keep up with the timer (because it takes longer than those 10 seconds to |
2122 | keep up with the timer (because it takes longer than those 10 seconds to |
2109 | do stuff) the timer will not fire more than once per event loop iteration. |
2123 | do stuff) the timer will not fire more than once per event loop iteration. |
2110 | |
2124 | |
2111 | =item ev_timer_again (loop, ev_timer *) |
2125 | =item ev_timer_again (loop, ev_timer *) |
2112 | |
2126 | |
2113 | This will act as if the timer timed out and restarts it again if it is |
2127 | This will act as if the timer timed out, and restarts it again if it is |
2114 | repeating. The exact semantics are: |
2128 | repeating. It basically works like calling C<ev_timer_stop>, updating the |
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2129 | timeout to the C<repeat> value and calling C<ev_timer_start>. |
2115 | |
2130 | |
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2131 | The exact semantics are as in the following rules, all of which will be |
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2132 | applied to the watcher: |
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2133 | |
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2134 | =over 4 |
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2135 | |
2116 | If the timer is pending, its pending status is cleared. |
2136 | =item If the timer is pending, the pending status is always cleared. |
2117 | |
2137 | |
2118 | If the timer is started but non-repeating, stop it (as if it timed out). |
2138 | =item If the timer is started but non-repeating, stop it (as if it timed |
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2139 | out, without invoking it). |
2119 | |
2140 | |
2120 | If the timer is repeating, either start it if necessary (with the |
2141 | =item If the timer is repeating, make the C<repeat> value the new timeout |
2121 | C<repeat> value), or reset the running timer to the C<repeat> value. |
2142 | and start the timer, if necessary. |
2122 | |
2143 | |
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2144 | =back |
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2145 | |
2123 | This sounds a bit complicated, see L<Be smart about timeouts>, above, for a |
2146 | This sounds a bit complicated, see L</Be smart about timeouts>, above, for a |
2124 | usage example. |
2147 | usage example. |
2125 | |
2148 | |
2126 | =item ev_tstamp ev_timer_remaining (loop, ev_timer *) |
2149 | =item ev_tstamp ev_timer_remaining (loop, ev_timer *) |
2127 | |
2150 | |
2128 | Returns the remaining time until a timer fires. If the timer is active, |
2151 | Returns the remaining time until a timer fires. If the timer is active, |
… | |
… | |
2371 | |
2394 | |
2372 | ev_periodic hourly_tick; |
2395 | ev_periodic hourly_tick; |
2373 | ev_periodic_init (&hourly_tick, clock_cb, |
2396 | ev_periodic_init (&hourly_tick, clock_cb, |
2374 | fmod (ev_now (loop), 3600.), 3600., 0); |
2397 | fmod (ev_now (loop), 3600.), 3600., 0); |
2375 | ev_periodic_start (loop, &hourly_tick); |
2398 | ev_periodic_start (loop, &hourly_tick); |
2376 | |
2399 | |
2377 | |
2400 | |
2378 | =head2 C<ev_signal> - signal me when a signal gets signalled! |
2401 | =head2 C<ev_signal> - signal me when a signal gets signalled! |
2379 | |
2402 | |
2380 | Signal watchers will trigger an event when the process receives a specific |
2403 | Signal watchers will trigger an event when the process receives a specific |
2381 | signal one or more times. Even though signals are very asynchronous, libev |
2404 | signal one or more times. Even though signals are very asynchronous, libev |
… | |
… | |
2391 | only within the same loop, i.e. you can watch for C<SIGINT> in your |
2414 | only within the same loop, i.e. you can watch for C<SIGINT> in your |
2392 | default loop and for C<SIGIO> in another loop, but you cannot watch for |
2415 | default loop and for C<SIGIO> in another loop, but you cannot watch for |
2393 | C<SIGINT> in both the default loop and another loop at the same time. At |
2416 | C<SIGINT> in both the default loop and another loop at the same time. At |
2394 | the moment, C<SIGCHLD> is permanently tied to the default loop. |
2417 | the moment, C<SIGCHLD> is permanently tied to the default loop. |
2395 | |
2418 | |
2396 | When the first watcher gets started will libev actually register something |
2419 | Only after the first watcher for a signal is started will libev actually |
2397 | with the kernel (thus it coexists with your own signal handlers as long as |
2420 | register something with the kernel. It thus coexists with your own signal |
2398 | you don't register any with libev for the same signal). |
2421 | handlers as long as you don't register any with libev for the same signal. |
2399 | |
2422 | |
2400 | If possible and supported, libev will install its handlers with |
2423 | If possible and supported, libev will install its handlers with |
2401 | C<SA_RESTART> (or equivalent) behaviour enabled, so system calls should |
2424 | C<SA_RESTART> (or equivalent) behaviour enabled, so system calls should |
2402 | not be unduly interrupted. If you have a problem with system calls getting |
2425 | not be unduly interrupted. If you have a problem with system calls getting |
2403 | interrupted by signals you can block all signals in an C<ev_check> watcher |
2426 | interrupted by signals you can block all signals in an C<ev_check> watcher |
… | |
… | |
2588 | |
2611 | |
2589 | =head2 C<ev_stat> - did the file attributes just change? |
2612 | =head2 C<ev_stat> - did the file attributes just change? |
2590 | |
2613 | |
2591 | This watches a file system path for attribute changes. That is, it calls |
2614 | This watches a file system path for attribute changes. That is, it calls |
2592 | C<stat> on that path in regular intervals (or when the OS says it changed) |
2615 | C<stat> on that path in regular intervals (or when the OS says it changed) |
2593 | and sees if it changed compared to the last time, invoking the callback if |
2616 | and sees if it changed compared to the last time, invoking the callback |
2594 | it did. |
2617 | if it did. Starting the watcher C<stat>'s the file, so only changes that |
|
|
2618 | happen after the watcher has been started will be reported. |
2595 | |
2619 | |
2596 | The path does not need to exist: changing from "path exists" to "path does |
2620 | The path does not need to exist: changing from "path exists" to "path does |
2597 | not exist" is a status change like any other. The condition "path does not |
2621 | not exist" is a status change like any other. The condition "path does not |
2598 | exist" (or more correctly "path cannot be stat'ed") is signified by the |
2622 | exist" (or more correctly "path cannot be stat'ed") is signified by the |
2599 | C<st_nlink> field being zero (which is otherwise always forced to be at |
2623 | C<st_nlink> field being zero (which is otherwise always forced to be at |
… | |
… | |
2829 | Apart from keeping your process non-blocking (which is a useful |
2853 | Apart from keeping your process non-blocking (which is a useful |
2830 | effect on its own sometimes), idle watchers are a good place to do |
2854 | effect on its own sometimes), idle watchers are a good place to do |
2831 | "pseudo-background processing", or delay processing stuff to after the |
2855 | "pseudo-background processing", or delay processing stuff to after the |
2832 | event loop has handled all outstanding events. |
2856 | event loop has handled all outstanding events. |
2833 | |
2857 | |
|
|
2858 | =head3 Abusing an C<ev_idle> watcher for its side-effect |
|
|
2859 | |
|
|
2860 | As long as there is at least one active idle watcher, libev will never |
|
|
2861 | sleep unnecessarily. Or in other words, it will loop as fast as possible. |
|
|
2862 | For this to work, the idle watcher doesn't need to be invoked at all - the |
|
|
2863 | lowest priority will do. |
|
|
2864 | |
|
|
2865 | This mode of operation can be useful together with an C<ev_check> watcher, |
|
|
2866 | to do something on each event loop iteration - for example to balance load |
|
|
2867 | between different connections. |
|
|
2868 | |
|
|
2869 | See L</Abusing an ev_check watcher for its side-effect> for a longer |
|
|
2870 | example. |
|
|
2871 | |
2834 | =head3 Watcher-Specific Functions and Data Members |
2872 | =head3 Watcher-Specific Functions and Data Members |
2835 | |
2873 | |
2836 | =over 4 |
2874 | =over 4 |
2837 | |
2875 | |
2838 | =item ev_idle_init (ev_idle *, callback) |
2876 | =item ev_idle_init (ev_idle *, callback) |
… | |
… | |
2849 | callback, free it. Also, use no error checking, as usual. |
2887 | callback, free it. Also, use no error checking, as usual. |
2850 | |
2888 | |
2851 | static void |
2889 | static void |
2852 | idle_cb (struct ev_loop *loop, ev_idle *w, int revents) |
2890 | idle_cb (struct ev_loop *loop, ev_idle *w, int revents) |
2853 | { |
2891 | { |
|
|
2892 | // stop the watcher |
|
|
2893 | ev_idle_stop (loop, w); |
|
|
2894 | |
|
|
2895 | // now we can free it |
2854 | free (w); |
2896 | free (w); |
|
|
2897 | |
2855 | // now do something you wanted to do when the program has |
2898 | // now do something you wanted to do when the program has |
2856 | // no longer anything immediate to do. |
2899 | // no longer anything immediate to do. |
2857 | } |
2900 | } |
2858 | |
2901 | |
2859 | ev_idle *idle_watcher = malloc (sizeof (ev_idle)); |
2902 | ev_idle *idle_watcher = malloc (sizeof (ev_idle)); |
… | |
… | |
2861 | ev_idle_start (loop, idle_watcher); |
2904 | ev_idle_start (loop, idle_watcher); |
2862 | |
2905 | |
2863 | |
2906 | |
2864 | =head2 C<ev_prepare> and C<ev_check> - customise your event loop! |
2907 | =head2 C<ev_prepare> and C<ev_check> - customise your event loop! |
2865 | |
2908 | |
2866 | Prepare and check watchers are usually (but not always) used in pairs: |
2909 | Prepare and check watchers are often (but not always) used in pairs: |
2867 | prepare watchers get invoked before the process blocks and check watchers |
2910 | prepare watchers get invoked before the process blocks and check watchers |
2868 | afterwards. |
2911 | afterwards. |
2869 | |
2912 | |
2870 | You I<must not> call C<ev_run> or similar functions that enter |
2913 | You I<must not> call C<ev_run> (or similar functions that enter the |
2871 | the current event loop from either C<ev_prepare> or C<ev_check> |
2914 | current event loop) or C<ev_loop_fork> from either C<ev_prepare> or |
2872 | watchers. Other loops than the current one are fine, however. The |
2915 | C<ev_check> watchers. Other loops than the current one are fine, |
2873 | rationale behind this is that you do not need to check for recursion in |
2916 | however. The rationale behind this is that you do not need to check |
2874 | those watchers, i.e. the sequence will always be C<ev_prepare>, blocking, |
2917 | for recursion in those watchers, i.e. the sequence will always be |
2875 | C<ev_check> so if you have one watcher of each kind they will always be |
2918 | C<ev_prepare>, blocking, C<ev_check> so if you have one watcher of each |
2876 | called in pairs bracketing the blocking call. |
2919 | kind they will always be called in pairs bracketing the blocking call. |
2877 | |
2920 | |
2878 | Their main purpose is to integrate other event mechanisms into libev and |
2921 | Their main purpose is to integrate other event mechanisms into libev and |
2879 | their use is somewhat advanced. They could be used, for example, to track |
2922 | their use is somewhat advanced. They could be used, for example, to track |
2880 | variable changes, implement your own watchers, integrate net-snmp or a |
2923 | variable changes, implement your own watchers, integrate net-snmp or a |
2881 | coroutine library and lots more. They are also occasionally useful if |
2924 | coroutine library and lots more. They are also occasionally useful if |
… | |
… | |
2899 | with priority higher than or equal to the event loop and one coroutine |
2942 | with priority higher than or equal to the event loop and one coroutine |
2900 | of lower priority, but only once, using idle watchers to keep the event |
2943 | of lower priority, but only once, using idle watchers to keep the event |
2901 | loop from blocking if lower-priority coroutines are active, thus mapping |
2944 | loop from blocking if lower-priority coroutines are active, thus mapping |
2902 | low-priority coroutines to idle/background tasks). |
2945 | low-priority coroutines to idle/background tasks). |
2903 | |
2946 | |
2904 | It is recommended to give C<ev_check> watchers highest (C<EV_MAXPRI>) |
2947 | When used for this purpose, it is recommended to give C<ev_check> watchers |
2905 | priority, to ensure that they are being run before any other watchers |
2948 | highest (C<EV_MAXPRI>) priority, to ensure that they are being run before |
2906 | after the poll (this doesn't matter for C<ev_prepare> watchers). |
2949 | any other watchers after the poll (this doesn't matter for C<ev_prepare> |
|
|
2950 | watchers). |
2907 | |
2951 | |
2908 | Also, C<ev_check> watchers (and C<ev_prepare> watchers, too) should not |
2952 | Also, C<ev_check> watchers (and C<ev_prepare> watchers, too) should not |
2909 | activate ("feed") events into libev. While libev fully supports this, they |
2953 | activate ("feed") events into libev. While libev fully supports this, they |
2910 | might get executed before other C<ev_check> watchers did their job. As |
2954 | might get executed before other C<ev_check> watchers did their job. As |
2911 | C<ev_check> watchers are often used to embed other (non-libev) event |
2955 | C<ev_check> watchers are often used to embed other (non-libev) event |
2912 | loops those other event loops might be in an unusable state until their |
2956 | loops those other event loops might be in an unusable state until their |
2913 | C<ev_check> watcher ran (always remind yourself to coexist peacefully with |
2957 | C<ev_check> watcher ran (always remind yourself to coexist peacefully with |
2914 | others). |
2958 | others). |
|
|
2959 | |
|
|
2960 | =head3 Abusing an C<ev_check> watcher for its side-effect |
|
|
2961 | |
|
|
2962 | C<ev_check> (and less often also C<ev_prepare>) watchers can also be |
|
|
2963 | useful because they are called once per event loop iteration. For |
|
|
2964 | example, if you want to handle a large number of connections fairly, you |
|
|
2965 | normally only do a bit of work for each active connection, and if there |
|
|
2966 | is more work to do, you wait for the next event loop iteration, so other |
|
|
2967 | connections have a chance of making progress. |
|
|
2968 | |
|
|
2969 | Using an C<ev_check> watcher is almost enough: it will be called on the |
|
|
2970 | next event loop iteration. However, that isn't as soon as possible - |
|
|
2971 | without external events, your C<ev_check> watcher will not be invoked. |
|
|
2972 | |
|
|
2973 | This is where C<ev_idle> watchers come in handy - all you need is a |
|
|
2974 | single global idle watcher that is active as long as you have one active |
|
|
2975 | C<ev_check> watcher. The C<ev_idle> watcher makes sure the event loop |
|
|
2976 | will not sleep, and the C<ev_check> watcher makes sure a callback gets |
|
|
2977 | invoked. Neither watcher alone can do that. |
2915 | |
2978 | |
2916 | =head3 Watcher-Specific Functions and Data Members |
2979 | =head3 Watcher-Specific Functions and Data Members |
2917 | |
2980 | |
2918 | =over 4 |
2981 | =over 4 |
2919 | |
2982 | |
… | |
… | |
3120 | |
3183 | |
3121 | =over 4 |
3184 | =over 4 |
3122 | |
3185 | |
3123 | =item ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop) |
3186 | =item ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop) |
3124 | |
3187 | |
3125 | =item ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop) |
3188 | =item ev_embed_set (ev_embed *, struct ev_loop *embedded_loop) |
3126 | |
3189 | |
3127 | Configures the watcher to embed the given loop, which must be |
3190 | Configures the watcher to embed the given loop, which must be |
3128 | embeddable. If the callback is C<0>, then C<ev_embed_sweep> will be |
3191 | embeddable. If the callback is C<0>, then C<ev_embed_sweep> will be |
3129 | invoked automatically, otherwise it is the responsibility of the callback |
3192 | invoked automatically, otherwise it is the responsibility of the callback |
3130 | to invoke it (it will continue to be called until the sweep has been done, |
3193 | to invoke it (it will continue to be called until the sweep has been done, |
… | |
… | |
3151 | used). |
3214 | used). |
3152 | |
3215 | |
3153 | struct ev_loop *loop_hi = ev_default_init (0); |
3216 | struct ev_loop *loop_hi = ev_default_init (0); |
3154 | struct ev_loop *loop_lo = 0; |
3217 | struct ev_loop *loop_lo = 0; |
3155 | ev_embed embed; |
3218 | ev_embed embed; |
3156 | |
3219 | |
3157 | // see if there is a chance of getting one that works |
3220 | // see if there is a chance of getting one that works |
3158 | // (remember that a flags value of 0 means autodetection) |
3221 | // (remember that a flags value of 0 means autodetection) |
3159 | loop_lo = ev_embeddable_backends () & ev_recommended_backends () |
3222 | loop_lo = ev_embeddable_backends () & ev_recommended_backends () |
3160 | ? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ()) |
3223 | ? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ()) |
3161 | : 0; |
3224 | : 0; |
… | |
… | |
3175 | C<loop_socket>. (One might optionally use C<EVFLAG_NOENV>, too). |
3238 | C<loop_socket>. (One might optionally use C<EVFLAG_NOENV>, too). |
3176 | |
3239 | |
3177 | struct ev_loop *loop = ev_default_init (0); |
3240 | struct ev_loop *loop = ev_default_init (0); |
3178 | struct ev_loop *loop_socket = 0; |
3241 | struct ev_loop *loop_socket = 0; |
3179 | ev_embed embed; |
3242 | ev_embed embed; |
3180 | |
3243 | |
3181 | if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE) |
3244 | if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE) |
3182 | if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE)) |
3245 | if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE)) |
3183 | { |
3246 | { |
3184 | ev_embed_init (&embed, 0, loop_socket); |
3247 | ev_embed_init (&embed, 0, loop_socket); |
3185 | ev_embed_start (loop, &embed); |
3248 | ev_embed_start (loop, &embed); |
… | |
… | |
3193 | |
3256 | |
3194 | =head2 C<ev_fork> - the audacity to resume the event loop after a fork |
3257 | =head2 C<ev_fork> - the audacity to resume the event loop after a fork |
3195 | |
3258 | |
3196 | Fork watchers are called when a C<fork ()> was detected (usually because |
3259 | Fork watchers are called when a C<fork ()> was detected (usually because |
3197 | whoever is a good citizen cared to tell libev about it by calling |
3260 | whoever is a good citizen cared to tell libev about it by calling |
3198 | C<ev_default_fork> or C<ev_loop_fork>). The invocation is done before the |
3261 | C<ev_loop_fork>). The invocation is done before the event loop blocks next |
3199 | event loop blocks next and before C<ev_check> watchers are being called, |
3262 | and before C<ev_check> watchers are being called, and only in the child |
3200 | and only in the child after the fork. If whoever good citizen calling |
3263 | after the fork. If whoever good citizen calling C<ev_default_fork> cheats |
3201 | C<ev_default_fork> cheats and calls it in the wrong process, the fork |
3264 | and calls it in the wrong process, the fork handlers will be invoked, too, |
3202 | handlers will be invoked, too, of course. |
3265 | of course. |
3203 | |
3266 | |
3204 | =head3 The special problem of life after fork - how is it possible? |
3267 | =head3 The special problem of life after fork - how is it possible? |
3205 | |
3268 | |
3206 | Most uses of C<fork()> consist of forking, then some simple calls to set |
3269 | Most uses of C<fork ()> consist of forking, then some simple calls to set |
3207 | up/change the process environment, followed by a call to C<exec()>. This |
3270 | up/change the process environment, followed by a call to C<exec()>. This |
3208 | sequence should be handled by libev without any problems. |
3271 | sequence should be handled by libev without any problems. |
3209 | |
3272 | |
3210 | This changes when the application actually wants to do event handling |
3273 | This changes when the application actually wants to do event handling |
3211 | in the child, or both parent in child, in effect "continuing" after the |
3274 | in the child, or both parent in child, in effect "continuing" after the |
… | |
… | |
3300 | it by calling C<ev_async_send>, which is thread- and signal safe. |
3363 | it by calling C<ev_async_send>, which is thread- and signal safe. |
3301 | |
3364 | |
3302 | This functionality is very similar to C<ev_signal> watchers, as signals, |
3365 | This functionality is very similar to C<ev_signal> watchers, as signals, |
3303 | too, are asynchronous in nature, and signals, too, will be compressed |
3366 | too, are asynchronous in nature, and signals, too, will be compressed |
3304 | (i.e. the number of callback invocations may be less than the number of |
3367 | (i.e. the number of callback invocations may be less than the number of |
3305 | C<ev_async_sent> calls). In fact, you could use signal watchers as a kind |
3368 | C<ev_async_send> calls). In fact, you could use signal watchers as a kind |
3306 | of "global async watchers" by using a watcher on an otherwise unused |
3369 | of "global async watchers" by using a watcher on an otherwise unused |
3307 | signal, and C<ev_feed_signal> to signal this watcher from another thread, |
3370 | signal, and C<ev_feed_signal> to signal this watcher from another thread, |
3308 | even without knowing which loop owns the signal. |
3371 | even without knowing which loop owns the signal. |
3309 | |
3372 | |
3310 | =head3 Queueing |
3373 | =head3 Queueing |
… | |
… | |
3601 | already been invoked. |
3664 | already been invoked. |
3602 | |
3665 | |
3603 | A common way around all these issues is to make sure that |
3666 | A common way around all these issues is to make sure that |
3604 | C<start_new_request> I<always> returns before the callback is invoked. If |
3667 | C<start_new_request> I<always> returns before the callback is invoked. If |
3605 | C<start_new_request> immediately knows the result, it can artificially |
3668 | C<start_new_request> immediately knows the result, it can artificially |
3606 | delay invoking the callback by e.g. using a C<prepare> or C<idle> watcher |
3669 | delay invoking the callback by using a C<prepare> or C<idle> watcher for |
3607 | for example, or more sneakily, by reusing an existing (stopped) watcher |
3670 | example, or more sneakily, by reusing an existing (stopped) watcher and |
3608 | and pushing it into the pending queue: |
3671 | pushing it into the pending queue: |
3609 | |
3672 | |
3610 | ev_set_cb (watcher, callback); |
3673 | ev_set_cb (watcher, callback); |
3611 | ev_feed_event (EV_A_ watcher, 0); |
3674 | ev_feed_event (EV_A_ watcher, 0); |
3612 | |
3675 | |
3613 | This way, C<start_new_request> can safely return before the callback is |
3676 | This way, C<start_new_request> can safely return before the callback is |
… | |
… | |
3621 | |
3684 | |
3622 | This brings the problem of exiting - a callback might want to finish the |
3685 | This brings the problem of exiting - a callback might want to finish the |
3623 | main C<ev_run> call, but not the nested one (e.g. user clicked "Quit", but |
3686 | main C<ev_run> call, but not the nested one (e.g. user clicked "Quit", but |
3624 | a modal "Are you sure?" dialog is still waiting), or just the nested one |
3687 | a modal "Are you sure?" dialog is still waiting), or just the nested one |
3625 | and not the main one (e.g. user clocked "Ok" in a modal dialog), or some |
3688 | and not the main one (e.g. user clocked "Ok" in a modal dialog), or some |
3626 | other combination: In these cases, C<ev_break> will not work alone. |
3689 | other combination: In these cases, a simple C<ev_break> will not work. |
3627 | |
3690 | |
3628 | The solution is to maintain "break this loop" variable for each C<ev_run> |
3691 | The solution is to maintain "break this loop" variable for each C<ev_run> |
3629 | invocation, and use a loop around C<ev_run> until the condition is |
3692 | invocation, and use a loop around C<ev_run> until the condition is |
3630 | triggered, using C<EVRUN_ONCE>: |
3693 | triggered, using C<EVRUN_ONCE>: |
3631 | |
3694 | |
… | |
… | |
3817 | called): |
3880 | called): |
3818 | |
3881 | |
3819 | void |
3882 | void |
3820 | wait_for_event (ev_watcher *w) |
3883 | wait_for_event (ev_watcher *w) |
3821 | { |
3884 | { |
3822 | ev_cb_set (w) = current_coro; |
3885 | ev_set_cb (w, current_coro); |
3823 | switch_to (libev_coro); |
3886 | switch_to (libev_coro); |
3824 | } |
3887 | } |
3825 | |
3888 | |
3826 | That basically suspends the coroutine inside C<wait_for_event> and |
3889 | That basically suspends the coroutine inside C<wait_for_event> and |
3827 | continues the libev coroutine, which, when appropriate, switches back to |
3890 | continues the libev coroutine, which, when appropriate, switches back to |
… | |
… | |
3830 | You can do similar tricks if you have, say, threads with an event queue - |
3893 | You can do similar tricks if you have, say, threads with an event queue - |
3831 | instead of storing a coroutine, you store the queue object and instead of |
3894 | instead of storing a coroutine, you store the queue object and instead of |
3832 | switching to a coroutine, you push the watcher onto the queue and notify |
3895 | switching to a coroutine, you push the watcher onto the queue and notify |
3833 | any waiters. |
3896 | any waiters. |
3834 | |
3897 | |
3835 | To embed libev, see L<EMBEDDING>, but in short, it's easiest to create two |
3898 | To embed libev, see L</EMBEDDING>, but in short, it's easiest to create two |
3836 | files, F<my_ev.h> and F<my_ev.c> that include the respective libev files: |
3899 | files, F<my_ev.h> and F<my_ev.c> that include the respective libev files: |
3837 | |
3900 | |
3838 | // my_ev.h |
3901 | // my_ev.h |
3839 | #define EV_CB_DECLARE(type) struct my_coro *cb; |
3902 | #define EV_CB_DECLARE(type) struct my_coro *cb; |
3840 | #define EV_CB_INVOKE(watcher) switch_to ((watcher)->cb); |
3903 | #define EV_CB_INVOKE(watcher) switch_to ((watcher)->cb); |
… | |
… | |
3884 | |
3947 | |
3885 | =back |
3948 | =back |
3886 | |
3949 | |
3887 | =head1 C++ SUPPORT |
3950 | =head1 C++ SUPPORT |
3888 | |
3951 | |
|
|
3952 | =head2 C API |
|
|
3953 | |
|
|
3954 | The normal C API should work fine when used from C++: both ev.h and the |
|
|
3955 | libev sources can be compiled as C++. Therefore, code that uses the C API |
|
|
3956 | will work fine. |
|
|
3957 | |
|
|
3958 | Proper exception specifications might have to be added to callbacks passed |
|
|
3959 | to libev: exceptions may be thrown only from watcher callbacks, all |
|
|
3960 | other callbacks (allocator, syserr, loop acquire/release and periodic |
|
|
3961 | reschedule callbacks) must not throw exceptions, and might need a C<throw |
|
|
3962 | ()> specification. If you have code that needs to be compiled as both C |
|
|
3963 | and C++ you can use the C<EV_THROW> macro for this: |
|
|
3964 | |
|
|
3965 | static void |
|
|
3966 | fatal_error (const char *msg) EV_THROW |
|
|
3967 | { |
|
|
3968 | perror (msg); |
|
|
3969 | abort (); |
|
|
3970 | } |
|
|
3971 | |
|
|
3972 | ... |
|
|
3973 | ev_set_syserr_cb (fatal_error); |
|
|
3974 | |
|
|
3975 | The only API functions that can currently throw exceptions are C<ev_run>, |
|
|
3976 | C<ev_invoke>, C<ev_invoke_pending> and C<ev_loop_destroy> (the latter |
|
|
3977 | because it runs cleanup watchers). |
|
|
3978 | |
|
|
3979 | Throwing exceptions in watcher callbacks is only supported if libev itself |
|
|
3980 | is compiled with a C++ compiler or your C and C++ environments allow |
|
|
3981 | throwing exceptions through C libraries (most do). |
|
|
3982 | |
|
|
3983 | =head2 C++ API |
|
|
3984 | |
3889 | Libev comes with some simplistic wrapper classes for C++ that mainly allow |
3985 | Libev comes with some simplistic wrapper classes for C++ that mainly allow |
3890 | you to use some convenience methods to start/stop watchers and also change |
3986 | you to use some convenience methods to start/stop watchers and also change |
3891 | the callback model to a model using method callbacks on objects. |
3987 | the callback model to a model using method callbacks on objects. |
3892 | |
3988 | |
3893 | To use it, |
3989 | To use it, |
3894 | |
3990 | |
3895 | #include <ev++.h> |
3991 | #include <ev++.h> |
3896 | |
3992 | |
3897 | This automatically includes F<ev.h> and puts all of its definitions (many |
3993 | This automatically includes F<ev.h> and puts all of its definitions (many |
3898 | of them macros) into the global namespace. All C++ specific things are |
3994 | of them macros) into the global namespace. All C++ specific things are |
3899 | put into the C<ev> namespace. It should support all the same embedding |
3995 | put into the C<ev> namespace. It should support all the same embedding |
… | |
… | |
3907 | Currently, functions, static and non-static member functions and classes |
4003 | Currently, functions, static and non-static member functions and classes |
3908 | with C<operator ()> can be used as callbacks. Other types should be easy |
4004 | with C<operator ()> can be used as callbacks. Other types should be easy |
3909 | to add as long as they only need one additional pointer for context. If |
4005 | to add as long as they only need one additional pointer for context. If |
3910 | you need support for other types of functors please contact the author |
4006 | you need support for other types of functors please contact the author |
3911 | (preferably after implementing it). |
4007 | (preferably after implementing it). |
|
|
4008 | |
|
|
4009 | For all this to work, your C++ compiler either has to use the same calling |
|
|
4010 | conventions as your C compiler (for static member functions), or you have |
|
|
4011 | to embed libev and compile libev itself as C++. |
3912 | |
4012 | |
3913 | Here is a list of things available in the C<ev> namespace: |
4013 | Here is a list of things available in the C<ev> namespace: |
3914 | |
4014 | |
3915 | =over 4 |
4015 | =over 4 |
3916 | |
4016 | |
… | |
… | |
3998 | void operator() (ev::io &w, int revents) |
4098 | void operator() (ev::io &w, int revents) |
3999 | { |
4099 | { |
4000 | ... |
4100 | ... |
4001 | } |
4101 | } |
4002 | } |
4102 | } |
4003 | |
4103 | |
4004 | myfunctor f; |
4104 | myfunctor f; |
4005 | |
4105 | |
4006 | ev::io w; |
4106 | ev::io w; |
4007 | w.set (&f); |
4107 | w.set (&f); |
4008 | |
4108 | |
… | |
… | |
4026 | Associates a different C<struct ev_loop> with this watcher. You can only |
4126 | Associates a different C<struct ev_loop> with this watcher. You can only |
4027 | do this when the watcher is inactive (and not pending either). |
4127 | do this when the watcher is inactive (and not pending either). |
4028 | |
4128 | |
4029 | =item w->set ([arguments]) |
4129 | =item w->set ([arguments]) |
4030 | |
4130 | |
4031 | Basically the same as C<ev_TYPE_set>, with the same arguments. Either this |
4131 | Basically the same as C<ev_TYPE_set> (except for C<ev::embed> watchers>), |
4032 | method or a suitable start method must be called at least once. Unlike the |
4132 | with the same arguments. Either this method or a suitable start method |
4033 | C counterpart, an active watcher gets automatically stopped and restarted |
4133 | must be called at least once. Unlike the C counterpart, an active watcher |
4034 | when reconfiguring it with this method. |
4134 | gets automatically stopped and restarted when reconfiguring it with this |
|
|
4135 | method. |
|
|
4136 | |
|
|
4137 | For C<ev::embed> watchers this method is called C<set_embed>, to avoid |
|
|
4138 | clashing with the C<set (loop)> method. |
4035 | |
4139 | |
4036 | =item w->start () |
4140 | =item w->start () |
4037 | |
4141 | |
4038 | Starts the watcher. Note that there is no C<loop> argument, as the |
4142 | Starts the watcher. Note that there is no C<loop> argument, as the |
4039 | constructor already stores the event loop. |
4143 | constructor already stores the event loop. |
… | |
… | |
4142 | =item Lua |
4246 | =item Lua |
4143 | |
4247 | |
4144 | Brian Maher has written a partial interface to libev for lua (at the |
4248 | Brian Maher has written a partial interface to libev for lua (at the |
4145 | time of this writing, only C<ev_io> and C<ev_timer>), to be found at |
4249 | time of this writing, only C<ev_io> and C<ev_timer>), to be found at |
4146 | L<http://github.com/brimworks/lua-ev>. |
4250 | L<http://github.com/brimworks/lua-ev>. |
|
|
4251 | |
|
|
4252 | =item Javascript |
|
|
4253 | |
|
|
4254 | Node.js (L<http://nodejs.org>) uses libev as the underlying event library. |
|
|
4255 | |
|
|
4256 | =item Others |
|
|
4257 | |
|
|
4258 | There are others, and I stopped counting. |
4147 | |
4259 | |
4148 | =back |
4260 | =back |
4149 | |
4261 | |
4150 | |
4262 | |
4151 | =head1 MACRO MAGIC |
4263 | =head1 MACRO MAGIC |
… | |
… | |
4450 | |
4562 | |
4451 | If programs implement their own fd to handle mapping on win32, then this |
4563 | If programs implement their own fd to handle mapping on win32, then this |
4452 | macro can be used to override the C<close> function, useful to unregister |
4564 | macro can be used to override the C<close> function, useful to unregister |
4453 | file descriptors again. Note that the replacement function has to close |
4565 | file descriptors again. Note that the replacement function has to close |
4454 | the underlying OS handle. |
4566 | the underlying OS handle. |
|
|
4567 | |
|
|
4568 | =item EV_USE_WSASOCKET |
|
|
4569 | |
|
|
4570 | If defined to be C<1>, libev will use C<WSASocket> to create its internal |
|
|
4571 | communication socket, which works better in some environments. Otherwise, |
|
|
4572 | the normal C<socket> function will be used, which works better in other |
|
|
4573 | environments. |
4455 | |
4574 | |
4456 | =item EV_USE_POLL |
4575 | =item EV_USE_POLL |
4457 | |
4576 | |
4458 | If defined to be C<1>, libev will compile in support for the C<poll>(2) |
4577 | If defined to be C<1>, libev will compile in support for the C<poll>(2) |
4459 | backend. Otherwise it will be enabled on non-win32 platforms. It |
4578 | backend. Otherwise it will be enabled on non-win32 platforms. It |
… | |
… | |
4495 | If defined to be C<1>, libev will compile in support for the Linux inotify |
4614 | If defined to be C<1>, libev will compile in support for the Linux inotify |
4496 | interface to speed up C<ev_stat> watchers. Its actual availability will |
4615 | interface to speed up C<ev_stat> watchers. Its actual availability will |
4497 | be detected at runtime. If undefined, it will be enabled if the headers |
4616 | be detected at runtime. If undefined, it will be enabled if the headers |
4498 | indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled. |
4617 | indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled. |
4499 | |
4618 | |
|
|
4619 | =item EV_NO_SMP |
|
|
4620 | |
|
|
4621 | If defined to be C<1>, libev will assume that memory is always coherent |
|
|
4622 | between threads, that is, threads can be used, but threads never run on |
|
|
4623 | different cpus (or different cpu cores). This reduces dependencies |
|
|
4624 | and makes libev faster. |
|
|
4625 | |
|
|
4626 | =item EV_NO_THREADS |
|
|
4627 | |
|
|
4628 | If defined to be C<1>, libev will assume that it will never be called from |
|
|
4629 | different threads (that includes signal handlers), which is a stronger |
|
|
4630 | assumption than C<EV_NO_SMP>, above. This reduces dependencies and makes |
|
|
4631 | libev faster. |
|
|
4632 | |
4500 | =item EV_ATOMIC_T |
4633 | =item EV_ATOMIC_T |
4501 | |
4634 | |
4502 | Libev requires an integer type (suitable for storing C<0> or C<1>) whose |
4635 | Libev requires an integer type (suitable for storing C<0> or C<1>) whose |
4503 | access is atomic and serialised with respect to other threads or signal |
4636 | access is atomic with respect to other threads or signal contexts. No |
4504 | contexts. No such type is easily found in the C language, so you can |
4637 | such type is easily found in the C language, so you can provide your own |
4505 | provide your own type that you know is safe for your purposes. It is used |
4638 | type that you know is safe for your purposes. It is used both for signal |
4506 | both for signal handler "locking" as well as for signal and thread safety |
4639 | handler "locking" as well as for signal and thread safety in C<ev_async> |
4507 | in C<ev_async> watchers. |
4640 | watchers. |
4508 | |
4641 | |
4509 | In the absence of this define, libev will use C<sig_atomic_t volatile> |
4642 | In the absence of this define, libev will use C<sig_atomic_t volatile> |
4510 | (from F<signal.h>), which is usually good enough on most platforms, |
4643 | (from F<signal.h>), which is usually good enough on most platforms. |
4511 | although strictly speaking using a type that also implies a memory fence |
|
|
4512 | is required. |
|
|
4513 | |
4644 | |
4514 | =item EV_H (h) |
4645 | =item EV_H (h) |
4515 | |
4646 | |
4516 | The name of the F<ev.h> header file used to include it. The default if |
4647 | The name of the F<ev.h> header file used to include it. The default if |
4517 | undefined is C<"ev.h"> in F<event.h>, F<ev.c> and F<ev++.h>. This can be |
4648 | undefined is C<"ev.h"> in F<event.h>, F<ev.c> and F<ev++.h>. This can be |
… | |
… | |
4590 | #define EV_USE_POLL 1 |
4721 | #define EV_USE_POLL 1 |
4591 | #define EV_CHILD_ENABLE 1 |
4722 | #define EV_CHILD_ENABLE 1 |
4592 | #define EV_ASYNC_ENABLE 1 |
4723 | #define EV_ASYNC_ENABLE 1 |
4593 | |
4724 | |
4594 | The actual value is a bitset, it can be a combination of the following |
4725 | The actual value is a bitset, it can be a combination of the following |
4595 | values: |
4726 | values (by default, all of these are enabled): |
4596 | |
4727 | |
4597 | =over 4 |
4728 | =over 4 |
4598 | |
4729 | |
4599 | =item C<1> - faster/larger code |
4730 | =item C<1> - faster/larger code |
4600 | |
4731 | |
… | |
… | |
4604 | code size by roughly 30% on amd64). |
4735 | code size by roughly 30% on amd64). |
4605 | |
4736 | |
4606 | When optimising for size, use of compiler flags such as C<-Os> with |
4737 | When optimising for size, use of compiler flags such as C<-Os> with |
4607 | gcc is recommended, as well as C<-DNDEBUG>, as libev contains a number of |
4738 | gcc is recommended, as well as C<-DNDEBUG>, as libev contains a number of |
4608 | assertions. |
4739 | assertions. |
|
|
4740 | |
|
|
4741 | The default is off when C<__OPTIMIZE_SIZE__> is defined by your compiler |
|
|
4742 | (e.g. gcc with C<-Os>). |
4609 | |
4743 | |
4610 | =item C<2> - faster/larger data structures |
4744 | =item C<2> - faster/larger data structures |
4611 | |
4745 | |
4612 | Replaces the small 2-heap for timer management by a faster 4-heap, larger |
4746 | Replaces the small 2-heap for timer management by a faster 4-heap, larger |
4613 | hash table sizes and so on. This will usually further increase code size |
4747 | hash table sizes and so on. This will usually further increase code size |
4614 | and can additionally have an effect on the size of data structures at |
4748 | and can additionally have an effect on the size of data structures at |
4615 | runtime. |
4749 | runtime. |
|
|
4750 | |
|
|
4751 | The default is off when C<__OPTIMIZE_SIZE__> is defined by your compiler |
|
|
4752 | (e.g. gcc with C<-Os>). |
4616 | |
4753 | |
4617 | =item C<4> - full API configuration |
4754 | =item C<4> - full API configuration |
4618 | |
4755 | |
4619 | This enables priorities (sets C<EV_MAXPRI>=2 and C<EV_MINPRI>=-2), and |
4756 | This enables priorities (sets C<EV_MAXPRI>=2 and C<EV_MINPRI>=-2), and |
4620 | enables multiplicity (C<EV_MULTIPLICITY>=1). |
4757 | enables multiplicity (C<EV_MULTIPLICITY>=1). |
… | |
… | |
4879 | default loop and triggering an C<ev_async> watcher from the default loop |
5016 | default loop and triggering an C<ev_async> watcher from the default loop |
4880 | watcher callback into the event loop interested in the signal. |
5017 | watcher callback into the event loop interested in the signal. |
4881 | |
5018 | |
4882 | =back |
5019 | =back |
4883 | |
5020 | |
4884 | See also L<THREAD LOCKING EXAMPLE>. |
5021 | See also L</THREAD LOCKING EXAMPLE>. |
4885 | |
5022 | |
4886 | =head3 COROUTINES |
5023 | =head3 COROUTINES |
4887 | |
5024 | |
4888 | Libev is very accommodating to coroutines ("cooperative threads"): |
5025 | Libev is very accommodating to coroutines ("cooperative threads"): |
4889 | libev fully supports nesting calls to its functions from different |
5026 | libev fully supports nesting calls to its functions from different |
… | |
… | |
5180 | thread" or will block signals process-wide, both behaviours would |
5317 | thread" or will block signals process-wide, both behaviours would |
5181 | be compatible with libev. Interaction between C<sigprocmask> and |
5318 | be compatible with libev. Interaction between C<sigprocmask> and |
5182 | C<pthread_sigmask> could complicate things, however. |
5319 | C<pthread_sigmask> could complicate things, however. |
5183 | |
5320 | |
5184 | The most portable way to handle signals is to block signals in all threads |
5321 | The most portable way to handle signals is to block signals in all threads |
5185 | except the initial one, and run the default loop in the initial thread as |
5322 | except the initial one, and run the signal handling loop in the initial |
5186 | well. |
5323 | thread as well. |
5187 | |
5324 | |
5188 | =item C<long> must be large enough for common memory allocation sizes |
5325 | =item C<long> must be large enough for common memory allocation sizes |
5189 | |
5326 | |
5190 | To improve portability and simplify its API, libev uses C<long> internally |
5327 | To improve portability and simplify its API, libev uses C<long> internally |
5191 | instead of C<size_t> when allocating its data structures. On non-POSIX |
5328 | instead of C<size_t> when allocating its data structures. On non-POSIX |
… | |
… | |
5295 | =over 4 |
5432 | =over 4 |
5296 | |
5433 | |
5297 | =item C<EV_COMPAT3> backwards compatibility mechanism |
5434 | =item C<EV_COMPAT3> backwards compatibility mechanism |
5298 | |
5435 | |
5299 | The backward compatibility mechanism can be controlled by |
5436 | The backward compatibility mechanism can be controlled by |
5300 | C<EV_COMPAT3>. See L<PREPROCESSOR SYMBOLS/MACROS> in the L<EMBEDDING> |
5437 | C<EV_COMPAT3>. See L</"PREPROCESSOR SYMBOLS/MACROS"> in the L</EMBEDDING> |
5301 | section. |
5438 | section. |
5302 | |
5439 | |
5303 | =item C<ev_default_destroy> and C<ev_default_fork> have been removed |
5440 | =item C<ev_default_destroy> and C<ev_default_fork> have been removed |
5304 | |
5441 | |
5305 | These calls can be replaced easily by their C<ev_loop_xxx> counterparts: |
5442 | These calls can be replaced easily by their C<ev_loop_xxx> counterparts: |
… | |
… | |
5348 | =over 4 |
5485 | =over 4 |
5349 | |
5486 | |
5350 | =item active |
5487 | =item active |
5351 | |
5488 | |
5352 | A watcher is active as long as it has been started and not yet stopped. |
5489 | A watcher is active as long as it has been started and not yet stopped. |
5353 | See L<WATCHER STATES> for details. |
5490 | See L</WATCHER STATES> for details. |
5354 | |
5491 | |
5355 | =item application |
5492 | =item application |
5356 | |
5493 | |
5357 | In this document, an application is whatever is using libev. |
5494 | In this document, an application is whatever is using libev. |
5358 | |
5495 | |
… | |
… | |
5394 | watchers and events. |
5531 | watchers and events. |
5395 | |
5532 | |
5396 | =item pending |
5533 | =item pending |
5397 | |
5534 | |
5398 | A watcher is pending as soon as the corresponding event has been |
5535 | A watcher is pending as soon as the corresponding event has been |
5399 | detected. See L<WATCHER STATES> for details. |
5536 | detected. See L</WATCHER STATES> for details. |
5400 | |
5537 | |
5401 | =item real time |
5538 | =item real time |
5402 | |
5539 | |
5403 | The physical time that is observed. It is apparently strictly monotonic :) |
5540 | The physical time that is observed. It is apparently strictly monotonic :) |
5404 | |
5541 | |