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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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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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412 | GNU/Linux system for example, C<getpid> is actually a simple 5-insn sequence |
416 | GNU/Linux system for example, C<getpid> is actually a simple 5-insn sequence |
413 | without a system call and thus I<very> fast, but my GNU/Linux system also has |
417 | without a system call and thus I<very> fast, but my GNU/Linux system also has |
414 | C<pthread_atfork> which is even faster). |
418 | C<pthread_atfork> which is even faster). |
415 | |
419 | |
416 | The big advantage of this flag is that you can forget about fork (and |
420 | The big advantage of this flag is that you can forget about fork (and |
417 | forget about forgetting to tell libev about forking) when you use this |
421 | forget about forgetting to tell libev about forking, although you still |
418 | flag. |
422 | have to ignore C<SIGPIPE>) when you use this flag. |
419 | |
423 | |
420 | This flag setting cannot be overridden or specified in the C<LIBEV_FLAGS> |
424 | This flag setting cannot be overridden or specified in the C<LIBEV_FLAGS> |
421 | environment variable. |
425 | environment variable. |
422 | |
426 | |
423 | =item C<EVFLAG_NOINOTIFY> |
427 | =item C<EVFLAG_NOINOTIFY> |
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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 |
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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 | |
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694 | In addition, if you want to reuse a loop (via this function or |
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695 | C<EVFLAG_FORKCHECK>), you I<also> have to ignore C<SIGPIPE>. |
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696 | |
689 | Again, you I<have> to call it on I<any> loop that you want to re-use after |
697 | 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 |
698 | 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 |
699 | because some kernel interfaces *cough* I<kqueue> *cough* do funny things |
692 | during fork. |
700 | during fork. |
693 | |
701 | |
694 | On the other hand, you only need to call this function in the child |
702 | On the other hand, you only need to call this function in the child |
… | |
… | |
764 | |
772 | |
765 | This function is rarely useful, but when some event callback runs for a |
773 | 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 |
774 | very long time without entering the event loop, updating libev's idea of |
767 | the current time is a good idea. |
775 | the current time is a good idea. |
768 | |
776 | |
769 | See also L<The special problem of time updates> in the C<ev_timer> section. |
777 | See also L</The special problem of time updates> in the C<ev_timer> section. |
770 | |
778 | |
771 | =item ev_suspend (loop) |
779 | =item ev_suspend (loop) |
772 | |
780 | |
773 | =item ev_resume (loop) |
781 | =item ev_resume (loop) |
774 | |
782 | |
… | |
… | |
1174 | |
1182 | |
1175 | =item C<EV_PREPARE> |
1183 | =item C<EV_PREPARE> |
1176 | |
1184 | |
1177 | =item C<EV_CHECK> |
1185 | =item C<EV_CHECK> |
1178 | |
1186 | |
1179 | All C<ev_prepare> watchers are invoked just I<before> C<ev_run> starts |
1187 | All C<ev_prepare> watchers are invoked just I<before> C<ev_run> starts to |
1180 | to gather new events, and all C<ev_check> watchers are invoked just after |
1188 | gather new events, and all C<ev_check> watchers are queued (not invoked) |
1181 | C<ev_run> has gathered them, but before it invokes any callbacks for any |
1189 | just after C<ev_run> has gathered them, but before it queues any callbacks |
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1190 | for any received events. That means C<ev_prepare> watchers are the last |
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1191 | watchers invoked before the event loop sleeps or polls for new events, and |
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1192 | C<ev_check> watchers will be invoked before any other watchers of the same |
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1193 | or lower priority within an event loop iteration. |
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1194 | |
1182 | received events. Callbacks of both watcher types can start and stop as |
1195 | Callbacks of both watcher types can start and stop as many watchers as |
1183 | many watchers as they want, and all of them will be taken into account |
1196 | they want, and all of them will be taken into account (for example, a |
1184 | (for example, a C<ev_prepare> watcher might start an idle watcher to keep |
1197 | C<ev_prepare> watcher might start an idle watcher to keep C<ev_run> from |
1185 | C<ev_run> from blocking). |
1198 | blocking). |
1186 | |
1199 | |
1187 | =item C<EV_EMBED> |
1200 | =item C<EV_EMBED> |
1188 | |
1201 | |
1189 | The embedded event loop specified in the C<ev_embed> watcher needs attention. |
1202 | The embedded event loop specified in the C<ev_embed> watcher needs attention. |
1190 | |
1203 | |
… | |
… | |
1313 | |
1326 | |
1314 | =item callback ev_cb (ev_TYPE *watcher) |
1327 | =item callback ev_cb (ev_TYPE *watcher) |
1315 | |
1328 | |
1316 | Returns the callback currently set on the watcher. |
1329 | Returns the callback currently set on the watcher. |
1317 | |
1330 | |
1318 | =item ev_cb_set (ev_TYPE *watcher, callback) |
1331 | =item ev_set_cb (ev_TYPE *watcher, callback) |
1319 | |
1332 | |
1320 | Change the callback. You can change the callback at virtually any time |
1333 | Change the callback. You can change the callback at virtually any time |
1321 | (modulo threads). |
1334 | (modulo threads). |
1322 | |
1335 | |
1323 | =item ev_set_priority (ev_TYPE *watcher, int priority) |
1336 | =item ev_set_priority (ev_TYPE *watcher, int priority) |
… | |
… | |
1341 | or might not have been clamped to the valid range. |
1354 | or might not have been clamped to the valid range. |
1342 | |
1355 | |
1343 | The default priority used by watchers when no priority has been set is |
1356 | The default priority used by watchers when no priority has been set is |
1344 | always C<0>, which is supposed to not be too high and not be too low :). |
1357 | always C<0>, which is supposed to not be too high and not be too low :). |
1345 | |
1358 | |
1346 | See L<WATCHER PRIORITY MODELS>, below, for a more thorough treatment of |
1359 | See L</WATCHER PRIORITY MODELS>, below, for a more thorough treatment of |
1347 | priorities. |
1360 | priorities. |
1348 | |
1361 | |
1349 | =item ev_invoke (loop, ev_TYPE *watcher, int revents) |
1362 | =item ev_invoke (loop, ev_TYPE *watcher, int revents) |
1350 | |
1363 | |
1351 | Invoke the C<watcher> with the given C<loop> and C<revents>. Neither |
1364 | Invoke the C<watcher> with the given C<loop> and C<revents>. Neither |
… | |
… | |
1376 | See also C<ev_feed_fd_event> and C<ev_feed_signal_event> for related |
1389 | See also C<ev_feed_fd_event> and C<ev_feed_signal_event> for related |
1377 | functions that do not need a watcher. |
1390 | functions that do not need a watcher. |
1378 | |
1391 | |
1379 | =back |
1392 | =back |
1380 | |
1393 | |
1381 | See also the L<ASSOCIATING CUSTOM DATA WITH A WATCHER> and L<BUILDING YOUR |
1394 | See also the L</ASSOCIATING CUSTOM DATA WITH A WATCHER> and L</BUILDING YOUR |
1382 | OWN COMPOSITE WATCHERS> idioms. |
1395 | OWN COMPOSITE WATCHERS> idioms. |
1383 | |
1396 | |
1384 | =head2 WATCHER STATES |
1397 | =head2 WATCHER STATES |
1385 | |
1398 | |
1386 | There are various watcher states mentioned throughout this manual - |
1399 | There are various watcher states mentioned throughout this manual - |
… | |
… | |
1388 | transition between them will be described in more detail - and while these |
1401 | transition between them will be described in more detail - and while these |
1389 | rules might look complicated, they usually do "the right thing". |
1402 | rules might look complicated, they usually do "the right thing". |
1390 | |
1403 | |
1391 | =over 4 |
1404 | =over 4 |
1392 | |
1405 | |
1393 | =item initialiased |
1406 | =item initialised |
1394 | |
1407 | |
1395 | Before a watcher can be registered with the event loop it has to be |
1408 | Before a watcher can be registered with the event loop it has to be |
1396 | initialised. This can be done with a call to C<ev_TYPE_init>, or calls to |
1409 | initialised. This can be done with a call to C<ev_TYPE_init>, or calls to |
1397 | C<ev_init> followed by the watcher-specific C<ev_TYPE_set> function. |
1410 | C<ev_init> followed by the watcher-specific C<ev_TYPE_set> function. |
1398 | |
1411 | |
… | |
… | |
1874 | callback (EV_P_ ev_timer *w, int revents) |
1887 | callback (EV_P_ ev_timer *w, int revents) |
1875 | { |
1888 | { |
1876 | // calculate when the timeout would happen |
1889 | // calculate when the timeout would happen |
1877 | ev_tstamp after = last_activity - ev_now (EV_A) + timeout; |
1890 | ev_tstamp after = last_activity - ev_now (EV_A) + timeout; |
1878 | |
1891 | |
1879 | // if negative, it means we the timeout already occured |
1892 | // if negative, it means we the timeout already occurred |
1880 | if (after < 0.) |
1893 | if (after < 0.) |
1881 | { |
1894 | { |
1882 | // timeout occurred, take action |
1895 | // timeout occurred, take action |
1883 | } |
1896 | } |
1884 | else |
1897 | else |
… | |
… | |
1902 | |
1915 | |
1903 | Otherwise, we now the earliest time at which the timeout would trigger, |
1916 | Otherwise, we now the earliest time at which the timeout would trigger, |
1904 | and simply start the timer with this timeout value. |
1917 | and simply start the timer with this timeout value. |
1905 | |
1918 | |
1906 | In other words, each time the callback is invoked it will check whether |
1919 | In other words, each time the callback is invoked it will check whether |
1907 | the timeout cocured. If not, it will simply reschedule itself to check |
1920 | the timeout occurred. If not, it will simply reschedule itself to check |
1908 | again at the earliest time it could time out. Rinse. Repeat. |
1921 | again at the earliest time it could time out. Rinse. Repeat. |
1909 | |
1922 | |
1910 | This scheme causes more callback invocations (about one every 60 seconds |
1923 | This scheme causes more callback invocations (about one every 60 seconds |
1911 | minus half the average time between activity), but virtually no calls to |
1924 | minus half the average time between activity), but virtually no calls to |
1912 | libev to change the timeout. |
1925 | libev to change the timeout. |
… | |
… | |
1926 | if (activity detected) |
1939 | if (activity detected) |
1927 | last_activity = ev_now (EV_A); |
1940 | last_activity = ev_now (EV_A); |
1928 | |
1941 | |
1929 | When your timeout value changes, then the timeout can be changed by simply |
1942 | When your timeout value changes, then the timeout can be changed by simply |
1930 | providing a new value, stopping the timer and calling the callback, which |
1943 | providing a new value, stopping the timer and calling the callback, which |
1931 | will agaion do the right thing (for example, time out immediately :). |
1944 | will again do the right thing (for example, time out immediately :). |
1932 | |
1945 | |
1933 | timeout = new_value; |
1946 | timeout = new_value; |
1934 | ev_timer_stop (EV_A_ &timer); |
1947 | ev_timer_stop (EV_A_ &timer); |
1935 | callback (EV_A_ &timer, 0); |
1948 | callback (EV_A_ &timer, 0); |
1936 | |
1949 | |
… | |
… | |
2019 | |
2032 | |
2020 | The relative timeouts are calculated relative to the C<ev_now ()> |
2033 | The relative timeouts are calculated relative to the C<ev_now ()> |
2021 | time. This is usually the right thing as this timestamp refers to the time |
2034 | time. This is usually the right thing as this timestamp refers to the time |
2022 | of the event triggering whatever timeout you are modifying/starting. If |
2035 | of the event triggering whatever timeout you are modifying/starting. If |
2023 | you suspect event processing to be delayed and you I<need> to base the |
2036 | you suspect event processing to be delayed and you I<need> to base the |
2024 | timeout on the current time, use something like this to adjust for this: |
2037 | timeout on the current time, use something like the following to adjust |
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2038 | for it: |
2025 | |
2039 | |
2026 | ev_timer_set (&timer, after + ev_now () - ev_time (), 0.); |
2040 | ev_timer_set (&timer, after + (ev_time () - ev_now ()), 0.); |
2027 | |
2041 | |
2028 | If the event loop is suspended for a long time, you can also force an |
2042 | If the event loop is suspended for a long time, you can also force an |
2029 | update of the time returned by C<ev_now ()> by calling C<ev_now_update |
2043 | update of the time returned by C<ev_now ()> by calling C<ev_now_update |
2030 | ()>. |
2044 | ()>, although that will push the event time of all outstanding events |
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2045 | further into the future. |
2031 | |
2046 | |
2032 | =head3 The special problem of unsynchronised clocks |
2047 | =head3 The special problem of unsynchronised clocks |
2033 | |
2048 | |
2034 | Modern systems have a variety of clocks - libev itself uses the normal |
2049 | Modern systems have a variety of clocks - libev itself uses the normal |
2035 | "wall clock" clock and, if available, the monotonic clock (to avoid time |
2050 | "wall clock" clock and, if available, the monotonic clock (to avoid time |
… | |
… | |
2131 | =item If the timer is repeating, make the C<repeat> value the new timeout |
2146 | =item If the timer is repeating, make the C<repeat> value the new timeout |
2132 | and start the timer, if necessary. |
2147 | and start the timer, if necessary. |
2133 | |
2148 | |
2134 | =back |
2149 | =back |
2135 | |
2150 | |
2136 | This sounds a bit complicated, see L<Be smart about timeouts>, above, for a |
2151 | This sounds a bit complicated, see L</Be smart about timeouts>, above, for a |
2137 | usage example. |
2152 | usage example. |
2138 | |
2153 | |
2139 | =item ev_tstamp ev_timer_remaining (loop, ev_timer *) |
2154 | =item ev_tstamp ev_timer_remaining (loop, ev_timer *) |
2140 | |
2155 | |
2141 | Returns the remaining time until a timer fires. If the timer is active, |
2156 | Returns the remaining time until a timer fires. If the timer is active, |
… | |
… | |
2194 | Periodic watchers are also timers of a kind, but they are very versatile |
2209 | Periodic watchers are also timers of a kind, but they are very versatile |
2195 | (and unfortunately a bit complex). |
2210 | (and unfortunately a bit complex). |
2196 | |
2211 | |
2197 | Unlike C<ev_timer>, periodic watchers are not based on real time (or |
2212 | Unlike C<ev_timer>, periodic watchers are not based on real time (or |
2198 | relative time, the physical time that passes) but on wall clock time |
2213 | relative time, the physical time that passes) but on wall clock time |
2199 | (absolute time, the thing you can read on your calender or clock). The |
2214 | (absolute time, the thing you can read on your calendar or clock). The |
2200 | difference is that wall clock time can run faster or slower than real |
2215 | difference is that wall clock time can run faster or slower than real |
2201 | time, and time jumps are not uncommon (e.g. when you adjust your |
2216 | time, and time jumps are not uncommon (e.g. when you adjust your |
2202 | wrist-watch). |
2217 | wrist-watch). |
2203 | |
2218 | |
2204 | You can tell a periodic watcher to trigger after some specific point |
2219 | You can tell a periodic watcher to trigger after some specific point |
… | |
… | |
2384 | |
2399 | |
2385 | ev_periodic hourly_tick; |
2400 | ev_periodic hourly_tick; |
2386 | ev_periodic_init (&hourly_tick, clock_cb, |
2401 | ev_periodic_init (&hourly_tick, clock_cb, |
2387 | fmod (ev_now (loop), 3600.), 3600., 0); |
2402 | fmod (ev_now (loop), 3600.), 3600., 0); |
2388 | ev_periodic_start (loop, &hourly_tick); |
2403 | ev_periodic_start (loop, &hourly_tick); |
2389 | |
2404 | |
2390 | |
2405 | |
2391 | =head2 C<ev_signal> - signal me when a signal gets signalled! |
2406 | =head2 C<ev_signal> - signal me when a signal gets signalled! |
2392 | |
2407 | |
2393 | Signal watchers will trigger an event when the process receives a specific |
2408 | Signal watchers will trigger an event when the process receives a specific |
2394 | signal one or more times. Even though signals are very asynchronous, libev |
2409 | signal one or more times. Even though signals are very asynchronous, libev |
… | |
… | |
2404 | only within the same loop, i.e. you can watch for C<SIGINT> in your |
2419 | only within the same loop, i.e. you can watch for C<SIGINT> in your |
2405 | default loop and for C<SIGIO> in another loop, but you cannot watch for |
2420 | default loop and for C<SIGIO> in another loop, but you cannot watch for |
2406 | C<SIGINT> in both the default loop and another loop at the same time. At |
2421 | C<SIGINT> in both the default loop and another loop at the same time. At |
2407 | the moment, C<SIGCHLD> is permanently tied to the default loop. |
2422 | the moment, C<SIGCHLD> is permanently tied to the default loop. |
2408 | |
2423 | |
2409 | When the first watcher gets started will libev actually register something |
2424 | Only after the first watcher for a signal is started will libev actually |
2410 | with the kernel (thus it coexists with your own signal handlers as long as |
2425 | register something with the kernel. It thus coexists with your own signal |
2411 | you don't register any with libev for the same signal). |
2426 | handlers as long as you don't register any with libev for the same signal. |
2412 | |
2427 | |
2413 | If possible and supported, libev will install its handlers with |
2428 | If possible and supported, libev will install its handlers with |
2414 | C<SA_RESTART> (or equivalent) behaviour enabled, so system calls should |
2429 | C<SA_RESTART> (or equivalent) behaviour enabled, so system calls should |
2415 | not be unduly interrupted. If you have a problem with system calls getting |
2430 | not be unduly interrupted. If you have a problem with system calls getting |
2416 | interrupted by signals you can block all signals in an C<ev_check> watcher |
2431 | interrupted by signals you can block all signals in an C<ev_check> watcher |
… | |
… | |
2601 | |
2616 | |
2602 | =head2 C<ev_stat> - did the file attributes just change? |
2617 | =head2 C<ev_stat> - did the file attributes just change? |
2603 | |
2618 | |
2604 | This watches a file system path for attribute changes. That is, it calls |
2619 | This watches a file system path for attribute changes. That is, it calls |
2605 | C<stat> on that path in regular intervals (or when the OS says it changed) |
2620 | C<stat> on that path in regular intervals (or when the OS says it changed) |
2606 | and sees if it changed compared to the last time, invoking the callback if |
2621 | and sees if it changed compared to the last time, invoking the callback |
2607 | it did. |
2622 | if it did. Starting the watcher C<stat>'s the file, so only changes that |
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2623 | happen after the watcher has been started will be reported. |
2608 | |
2624 | |
2609 | The path does not need to exist: changing from "path exists" to "path does |
2625 | The path does not need to exist: changing from "path exists" to "path does |
2610 | not exist" is a status change like any other. The condition "path does not |
2626 | not exist" is a status change like any other. The condition "path does not |
2611 | exist" (or more correctly "path cannot be stat'ed") is signified by the |
2627 | exist" (or more correctly "path cannot be stat'ed") is signified by the |
2612 | C<st_nlink> field being zero (which is otherwise always forced to be at |
2628 | C<st_nlink> field being zero (which is otherwise always forced to be at |
… | |
… | |
2842 | Apart from keeping your process non-blocking (which is a useful |
2858 | Apart from keeping your process non-blocking (which is a useful |
2843 | effect on its own sometimes), idle watchers are a good place to do |
2859 | effect on its own sometimes), idle watchers are a good place to do |
2844 | "pseudo-background processing", or delay processing stuff to after the |
2860 | "pseudo-background processing", or delay processing stuff to after the |
2845 | event loop has handled all outstanding events. |
2861 | event loop has handled all outstanding events. |
2846 | |
2862 | |
|
|
2863 | =head3 Abusing an C<ev_idle> watcher for its side-effect |
|
|
2864 | |
|
|
2865 | As long as there is at least one active idle watcher, libev will never |
|
|
2866 | sleep unnecessarily. Or in other words, it will loop as fast as possible. |
|
|
2867 | For this to work, the idle watcher doesn't need to be invoked at all - the |
|
|
2868 | lowest priority will do. |
|
|
2869 | |
|
|
2870 | This mode of operation can be useful together with an C<ev_check> watcher, |
|
|
2871 | to do something on each event loop iteration - for example to balance load |
|
|
2872 | between different connections. |
|
|
2873 | |
|
|
2874 | See L</Abusing an ev_check watcher for its side-effect> for a longer |
|
|
2875 | example. |
|
|
2876 | |
2847 | =head3 Watcher-Specific Functions and Data Members |
2877 | =head3 Watcher-Specific Functions and Data Members |
2848 | |
2878 | |
2849 | =over 4 |
2879 | =over 4 |
2850 | |
2880 | |
2851 | =item ev_idle_init (ev_idle *, callback) |
2881 | =item ev_idle_init (ev_idle *, callback) |
… | |
… | |
2862 | callback, free it. Also, use no error checking, as usual. |
2892 | callback, free it. Also, use no error checking, as usual. |
2863 | |
2893 | |
2864 | static void |
2894 | static void |
2865 | idle_cb (struct ev_loop *loop, ev_idle *w, int revents) |
2895 | idle_cb (struct ev_loop *loop, ev_idle *w, int revents) |
2866 | { |
2896 | { |
|
|
2897 | // stop the watcher |
|
|
2898 | ev_idle_stop (loop, w); |
|
|
2899 | |
|
|
2900 | // now we can free it |
2867 | free (w); |
2901 | free (w); |
|
|
2902 | |
2868 | // now do something you wanted to do when the program has |
2903 | // now do something you wanted to do when the program has |
2869 | // no longer anything immediate to do. |
2904 | // no longer anything immediate to do. |
2870 | } |
2905 | } |
2871 | |
2906 | |
2872 | ev_idle *idle_watcher = malloc (sizeof (ev_idle)); |
2907 | ev_idle *idle_watcher = malloc (sizeof (ev_idle)); |
… | |
… | |
2874 | ev_idle_start (loop, idle_watcher); |
2909 | ev_idle_start (loop, idle_watcher); |
2875 | |
2910 | |
2876 | |
2911 | |
2877 | =head2 C<ev_prepare> and C<ev_check> - customise your event loop! |
2912 | =head2 C<ev_prepare> and C<ev_check> - customise your event loop! |
2878 | |
2913 | |
2879 | Prepare and check watchers are usually (but not always) used in pairs: |
2914 | Prepare and check watchers are often (but not always) used in pairs: |
2880 | prepare watchers get invoked before the process blocks and check watchers |
2915 | prepare watchers get invoked before the process blocks and check watchers |
2881 | afterwards. |
2916 | afterwards. |
2882 | |
2917 | |
2883 | You I<must not> call C<ev_run> or similar functions that enter |
2918 | You I<must not> call C<ev_run> (or similar functions that enter the |
2884 | the current event loop from either C<ev_prepare> or C<ev_check> |
2919 | current event loop) or C<ev_loop_fork> from either C<ev_prepare> or |
2885 | watchers. Other loops than the current one are fine, however. The |
2920 | C<ev_check> watchers. Other loops than the current one are fine, |
2886 | rationale behind this is that you do not need to check for recursion in |
2921 | however. The rationale behind this is that you do not need to check |
2887 | those watchers, i.e. the sequence will always be C<ev_prepare>, blocking, |
2922 | for recursion in those watchers, i.e. the sequence will always be |
2888 | C<ev_check> so if you have one watcher of each kind they will always be |
2923 | C<ev_prepare>, blocking, C<ev_check> so if you have one watcher of each |
2889 | called in pairs bracketing the blocking call. |
2924 | kind they will always be called in pairs bracketing the blocking call. |
2890 | |
2925 | |
2891 | Their main purpose is to integrate other event mechanisms into libev and |
2926 | Their main purpose is to integrate other event mechanisms into libev and |
2892 | their use is somewhat advanced. They could be used, for example, to track |
2927 | their use is somewhat advanced. They could be used, for example, to track |
2893 | variable changes, implement your own watchers, integrate net-snmp or a |
2928 | variable changes, implement your own watchers, integrate net-snmp or a |
2894 | coroutine library and lots more. They are also occasionally useful if |
2929 | coroutine library and lots more. They are also occasionally useful if |
… | |
… | |
2912 | with priority higher than or equal to the event loop and one coroutine |
2947 | with priority higher than or equal to the event loop and one coroutine |
2913 | of lower priority, but only once, using idle watchers to keep the event |
2948 | of lower priority, but only once, using idle watchers to keep the event |
2914 | loop from blocking if lower-priority coroutines are active, thus mapping |
2949 | loop from blocking if lower-priority coroutines are active, thus mapping |
2915 | low-priority coroutines to idle/background tasks). |
2950 | low-priority coroutines to idle/background tasks). |
2916 | |
2951 | |
2917 | It is recommended to give C<ev_check> watchers highest (C<EV_MAXPRI>) |
2952 | When used for this purpose, it is recommended to give C<ev_check> watchers |
2918 | priority, to ensure that they are being run before any other watchers |
2953 | highest (C<EV_MAXPRI>) priority, to ensure that they are being run before |
2919 | after the poll (this doesn't matter for C<ev_prepare> watchers). |
2954 | any other watchers after the poll (this doesn't matter for C<ev_prepare> |
|
|
2955 | watchers). |
2920 | |
2956 | |
2921 | Also, C<ev_check> watchers (and C<ev_prepare> watchers, too) should not |
2957 | Also, C<ev_check> watchers (and C<ev_prepare> watchers, too) should not |
2922 | activate ("feed") events into libev. While libev fully supports this, they |
2958 | activate ("feed") events into libev. While libev fully supports this, they |
2923 | might get executed before other C<ev_check> watchers did their job. As |
2959 | might get executed before other C<ev_check> watchers did their job. As |
2924 | C<ev_check> watchers are often used to embed other (non-libev) event |
2960 | C<ev_check> watchers are often used to embed other (non-libev) event |
2925 | loops those other event loops might be in an unusable state until their |
2961 | loops those other event loops might be in an unusable state until their |
2926 | C<ev_check> watcher ran (always remind yourself to coexist peacefully with |
2962 | C<ev_check> watcher ran (always remind yourself to coexist peacefully with |
2927 | others). |
2963 | others). |
|
|
2964 | |
|
|
2965 | =head3 Abusing an C<ev_check> watcher for its side-effect |
|
|
2966 | |
|
|
2967 | C<ev_check> (and less often also C<ev_prepare>) watchers can also be |
|
|
2968 | useful because they are called once per event loop iteration. For |
|
|
2969 | example, if you want to handle a large number of connections fairly, you |
|
|
2970 | normally only do a bit of work for each active connection, and if there |
|
|
2971 | is more work to do, you wait for the next event loop iteration, so other |
|
|
2972 | connections have a chance of making progress. |
|
|
2973 | |
|
|
2974 | Using an C<ev_check> watcher is almost enough: it will be called on the |
|
|
2975 | next event loop iteration. However, that isn't as soon as possible - |
|
|
2976 | without external events, your C<ev_check> watcher will not be invoked. |
|
|
2977 | |
|
|
2978 | This is where C<ev_idle> watchers come in handy - all you need is a |
|
|
2979 | single global idle watcher that is active as long as you have one active |
|
|
2980 | C<ev_check> watcher. The C<ev_idle> watcher makes sure the event loop |
|
|
2981 | will not sleep, and the C<ev_check> watcher makes sure a callback gets |
|
|
2982 | invoked. Neither watcher alone can do that. |
2928 | |
2983 | |
2929 | =head3 Watcher-Specific Functions and Data Members |
2984 | =head3 Watcher-Specific Functions and Data Members |
2930 | |
2985 | |
2931 | =over 4 |
2986 | =over 4 |
2932 | |
2987 | |
… | |
… | |
3133 | |
3188 | |
3134 | =over 4 |
3189 | =over 4 |
3135 | |
3190 | |
3136 | =item ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop) |
3191 | =item ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop) |
3137 | |
3192 | |
3138 | =item ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop) |
3193 | =item ev_embed_set (ev_embed *, struct ev_loop *embedded_loop) |
3139 | |
3194 | |
3140 | Configures the watcher to embed the given loop, which must be |
3195 | Configures the watcher to embed the given loop, which must be |
3141 | embeddable. If the callback is C<0>, then C<ev_embed_sweep> will be |
3196 | embeddable. If the callback is C<0>, then C<ev_embed_sweep> will be |
3142 | invoked automatically, otherwise it is the responsibility of the callback |
3197 | invoked automatically, otherwise it is the responsibility of the callback |
3143 | to invoke it (it will continue to be called until the sweep has been done, |
3198 | to invoke it (it will continue to be called until the sweep has been done, |
… | |
… | |
3164 | used). |
3219 | used). |
3165 | |
3220 | |
3166 | struct ev_loop *loop_hi = ev_default_init (0); |
3221 | struct ev_loop *loop_hi = ev_default_init (0); |
3167 | struct ev_loop *loop_lo = 0; |
3222 | struct ev_loop *loop_lo = 0; |
3168 | ev_embed embed; |
3223 | ev_embed embed; |
3169 | |
3224 | |
3170 | // see if there is a chance of getting one that works |
3225 | // see if there is a chance of getting one that works |
3171 | // (remember that a flags value of 0 means autodetection) |
3226 | // (remember that a flags value of 0 means autodetection) |
3172 | loop_lo = ev_embeddable_backends () & ev_recommended_backends () |
3227 | loop_lo = ev_embeddable_backends () & ev_recommended_backends () |
3173 | ? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ()) |
3228 | ? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ()) |
3174 | : 0; |
3229 | : 0; |
… | |
… | |
3188 | C<loop_socket>. (One might optionally use C<EVFLAG_NOENV>, too). |
3243 | C<loop_socket>. (One might optionally use C<EVFLAG_NOENV>, too). |
3189 | |
3244 | |
3190 | struct ev_loop *loop = ev_default_init (0); |
3245 | struct ev_loop *loop = ev_default_init (0); |
3191 | struct ev_loop *loop_socket = 0; |
3246 | struct ev_loop *loop_socket = 0; |
3192 | ev_embed embed; |
3247 | ev_embed embed; |
3193 | |
3248 | |
3194 | if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE) |
3249 | if (ev_supported_backends () & ~ev_recommended_backends () & EVBACKEND_KQUEUE) |
3195 | if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE)) |
3250 | if ((loop_socket = ev_loop_new (EVBACKEND_KQUEUE)) |
3196 | { |
3251 | { |
3197 | ev_embed_init (&embed, 0, loop_socket); |
3252 | ev_embed_init (&embed, 0, loop_socket); |
3198 | ev_embed_start (loop, &embed); |
3253 | ev_embed_start (loop, &embed); |
… | |
… | |
3206 | |
3261 | |
3207 | =head2 C<ev_fork> - the audacity to resume the event loop after a fork |
3262 | =head2 C<ev_fork> - the audacity to resume the event loop after a fork |
3208 | |
3263 | |
3209 | Fork watchers are called when a C<fork ()> was detected (usually because |
3264 | Fork watchers are called when a C<fork ()> was detected (usually because |
3210 | whoever is a good citizen cared to tell libev about it by calling |
3265 | whoever is a good citizen cared to tell libev about it by calling |
3211 | C<ev_default_fork> or C<ev_loop_fork>). The invocation is done before the |
3266 | C<ev_loop_fork>). The invocation is done before the event loop blocks next |
3212 | event loop blocks next and before C<ev_check> watchers are being called, |
3267 | and before C<ev_check> watchers are being called, and only in the child |
3213 | and only in the child after the fork. If whoever good citizen calling |
3268 | after the fork. If whoever good citizen calling C<ev_default_fork> cheats |
3214 | C<ev_default_fork> cheats and calls it in the wrong process, the fork |
3269 | and calls it in the wrong process, the fork handlers will be invoked, too, |
3215 | handlers will be invoked, too, of course. |
3270 | of course. |
3216 | |
3271 | |
3217 | =head3 The special problem of life after fork - how is it possible? |
3272 | =head3 The special problem of life after fork - how is it possible? |
3218 | |
3273 | |
3219 | Most uses of C<fork()> consist of forking, then some simple calls to set |
3274 | Most uses of C<fork ()> consist of forking, then some simple calls to set |
3220 | up/change the process environment, followed by a call to C<exec()>. This |
3275 | up/change the process environment, followed by a call to C<exec()>. This |
3221 | sequence should be handled by libev without any problems. |
3276 | sequence should be handled by libev without any problems. |
3222 | |
3277 | |
3223 | This changes when the application actually wants to do event handling |
3278 | This changes when the application actually wants to do event handling |
3224 | in the child, or both parent in child, in effect "continuing" after the |
3279 | in the child, or both parent in child, in effect "continuing" after the |
… | |
… | |
3313 | it by calling C<ev_async_send>, which is thread- and signal safe. |
3368 | it by calling C<ev_async_send>, which is thread- and signal safe. |
3314 | |
3369 | |
3315 | This functionality is very similar to C<ev_signal> watchers, as signals, |
3370 | This functionality is very similar to C<ev_signal> watchers, as signals, |
3316 | too, are asynchronous in nature, and signals, too, will be compressed |
3371 | too, are asynchronous in nature, and signals, too, will be compressed |
3317 | (i.e. the number of callback invocations may be less than the number of |
3372 | (i.e. the number of callback invocations may be less than the number of |
3318 | C<ev_async_sent> calls). In fact, you could use signal watchers as a kind |
3373 | C<ev_async_send> calls). In fact, you could use signal watchers as a kind |
3319 | of "global async watchers" by using a watcher on an otherwise unused |
3374 | of "global async watchers" by using a watcher on an otherwise unused |
3320 | signal, and C<ev_feed_signal> to signal this watcher from another thread, |
3375 | signal, and C<ev_feed_signal> to signal this watcher from another thread, |
3321 | even without knowing which loop owns the signal. |
3376 | even without knowing which loop owns the signal. |
3322 | |
3377 | |
3323 | =head3 Queueing |
3378 | =head3 Queueing |
… | |
… | |
3614 | already been invoked. |
3669 | already been invoked. |
3615 | |
3670 | |
3616 | A common way around all these issues is to make sure that |
3671 | A common way around all these issues is to make sure that |
3617 | C<start_new_request> I<always> returns before the callback is invoked. If |
3672 | C<start_new_request> I<always> returns before the callback is invoked. If |
3618 | C<start_new_request> immediately knows the result, it can artificially |
3673 | C<start_new_request> immediately knows the result, it can artificially |
3619 | delay invoking the callback by e.g. using a C<prepare> or C<idle> watcher |
3674 | delay invoking the callback by using a C<prepare> or C<idle> watcher for |
3620 | for example, or more sneakily, by reusing an existing (stopped) watcher |
3675 | example, or more sneakily, by reusing an existing (stopped) watcher and |
3621 | and pushing it into the pending queue: |
3676 | pushing it into the pending queue: |
3622 | |
3677 | |
3623 | ev_set_cb (watcher, callback); |
3678 | ev_set_cb (watcher, callback); |
3624 | ev_feed_event (EV_A_ watcher, 0); |
3679 | ev_feed_event (EV_A_ watcher, 0); |
3625 | |
3680 | |
3626 | This way, C<start_new_request> can safely return before the callback is |
3681 | This way, C<start_new_request> can safely return before the callback is |
… | |
… | |
3634 | |
3689 | |
3635 | This brings the problem of exiting - a callback might want to finish the |
3690 | This brings the problem of exiting - a callback might want to finish the |
3636 | main C<ev_run> call, but not the nested one (e.g. user clicked "Quit", but |
3691 | main C<ev_run> call, but not the nested one (e.g. user clicked "Quit", but |
3637 | a modal "Are you sure?" dialog is still waiting), or just the nested one |
3692 | a modal "Are you sure?" dialog is still waiting), or just the nested one |
3638 | and not the main one (e.g. user clocked "Ok" in a modal dialog), or some |
3693 | and not the main one (e.g. user clocked "Ok" in a modal dialog), or some |
3639 | other combination: In these cases, C<ev_break> will not work alone. |
3694 | other combination: In these cases, a simple C<ev_break> will not work. |
3640 | |
3695 | |
3641 | The solution is to maintain "break this loop" variable for each C<ev_run> |
3696 | The solution is to maintain "break this loop" variable for each C<ev_run> |
3642 | invocation, and use a loop around C<ev_run> until the condition is |
3697 | invocation, and use a loop around C<ev_run> until the condition is |
3643 | triggered, using C<EVRUN_ONCE>: |
3698 | triggered, using C<EVRUN_ONCE>: |
3644 | |
3699 | |
… | |
… | |
3830 | called): |
3885 | called): |
3831 | |
3886 | |
3832 | void |
3887 | void |
3833 | wait_for_event (ev_watcher *w) |
3888 | wait_for_event (ev_watcher *w) |
3834 | { |
3889 | { |
3835 | ev_cb_set (w) = current_coro; |
3890 | ev_set_cb (w, current_coro); |
3836 | switch_to (libev_coro); |
3891 | switch_to (libev_coro); |
3837 | } |
3892 | } |
3838 | |
3893 | |
3839 | That basically suspends the coroutine inside C<wait_for_event> and |
3894 | That basically suspends the coroutine inside C<wait_for_event> and |
3840 | continues the libev coroutine, which, when appropriate, switches back to |
3895 | continues the libev coroutine, which, when appropriate, switches back to |
… | |
… | |
3843 | You can do similar tricks if you have, say, threads with an event queue - |
3898 | You can do similar tricks if you have, say, threads with an event queue - |
3844 | instead of storing a coroutine, you store the queue object and instead of |
3899 | instead of storing a coroutine, you store the queue object and instead of |
3845 | switching to a coroutine, you push the watcher onto the queue and notify |
3900 | switching to a coroutine, you push the watcher onto the queue and notify |
3846 | any waiters. |
3901 | any waiters. |
3847 | |
3902 | |
3848 | To embed libev, see L<EMBEDDING>, but in short, it's easiest to create two |
3903 | To embed libev, see L</EMBEDDING>, but in short, it's easiest to create two |
3849 | files, F<my_ev.h> and F<my_ev.c> that include the respective libev files: |
3904 | files, F<my_ev.h> and F<my_ev.c> that include the respective libev files: |
3850 | |
3905 | |
3851 | // my_ev.h |
3906 | // my_ev.h |
3852 | #define EV_CB_DECLARE(type) struct my_coro *cb; |
3907 | #define EV_CB_DECLARE(type) struct my_coro *cb; |
3853 | #define EV_CB_INVOKE(watcher) switch_to ((watcher)->cb); |
3908 | #define EV_CB_INVOKE(watcher) switch_to ((watcher)->cb) |
3854 | #include "../libev/ev.h" |
3909 | #include "../libev/ev.h" |
3855 | |
3910 | |
3856 | // my_ev.c |
3911 | // my_ev.c |
3857 | #define EV_H "my_ev.h" |
3912 | #define EV_H "my_ev.h" |
3858 | #include "../libev/ev.c" |
3913 | #include "../libev/ev.c" |
… | |
… | |
3905 | libev sources can be compiled as C++. Therefore, code that uses the C API |
3960 | libev sources can be compiled as C++. Therefore, code that uses the C API |
3906 | will work fine. |
3961 | will work fine. |
3907 | |
3962 | |
3908 | Proper exception specifications might have to be added to callbacks passed |
3963 | Proper exception specifications might have to be added to callbacks passed |
3909 | to libev: exceptions may be thrown only from watcher callbacks, all |
3964 | to libev: exceptions may be thrown only from watcher callbacks, all |
3910 | other callbacks (allocator, syserr, loop acquire/release and periodioc |
3965 | other callbacks (allocator, syserr, loop acquire/release and periodic |
3911 | reschedule callbacks) must not throw exceptions, and might need a C<throw |
3966 | reschedule callbacks) must not throw exceptions, and might need a C<throw |
3912 | ()> specification. If you have code that needs to be compiled as both C |
3967 | ()> specification. If you have code that needs to be compiled as both C |
3913 | and C++ you can use the C<EV_THROW> macro for this: |
3968 | and C++ you can use the C<EV_THROW> macro for this: |
3914 | |
3969 | |
3915 | static void |
3970 | static void |
… | |
… | |
3921 | |
3976 | |
3922 | ... |
3977 | ... |
3923 | ev_set_syserr_cb (fatal_error); |
3978 | ev_set_syserr_cb (fatal_error); |
3924 | |
3979 | |
3925 | The only API functions that can currently throw exceptions are C<ev_run>, |
3980 | The only API functions that can currently throw exceptions are C<ev_run>, |
3926 | C<ev_inoke>, C<ev_invoke_pending> and C<ev_loop_destroy> (the latter |
3981 | C<ev_invoke>, C<ev_invoke_pending> and C<ev_loop_destroy> (the latter |
3927 | because it runs cleanup watchers). |
3982 | because it runs cleanup watchers). |
3928 | |
3983 | |
3929 | Throwing exceptions in watcher callbacks is only supported if libev itself |
3984 | Throwing exceptions in watcher callbacks is only supported if libev itself |
3930 | is compiled with a C++ compiler or your C and C++ environments allow |
3985 | is compiled with a C++ compiler or your C and C++ environments allow |
3931 | throwing exceptions through C libraries (most do). |
3986 | throwing exceptions through C libraries (most do). |
… | |
… | |
3935 | Libev comes with some simplistic wrapper classes for C++ that mainly allow |
3990 | Libev comes with some simplistic wrapper classes for C++ that mainly allow |
3936 | you to use some convenience methods to start/stop watchers and also change |
3991 | you to use some convenience methods to start/stop watchers and also change |
3937 | the callback model to a model using method callbacks on objects. |
3992 | the callback model to a model using method callbacks on objects. |
3938 | |
3993 | |
3939 | To use it, |
3994 | To use it, |
3940 | |
3995 | |
3941 | #include <ev++.h> |
3996 | #include <ev++.h> |
3942 | |
3997 | |
3943 | This automatically includes F<ev.h> and puts all of its definitions (many |
3998 | This automatically includes F<ev.h> and puts all of its definitions (many |
3944 | of them macros) into the global namespace. All C++ specific things are |
3999 | of them macros) into the global namespace. All C++ specific things are |
3945 | put into the C<ev> namespace. It should support all the same embedding |
4000 | put into the C<ev> namespace. It should support all the same embedding |
… | |
… | |
4048 | void operator() (ev::io &w, int revents) |
4103 | void operator() (ev::io &w, int revents) |
4049 | { |
4104 | { |
4050 | ... |
4105 | ... |
4051 | } |
4106 | } |
4052 | } |
4107 | } |
4053 | |
4108 | |
4054 | myfunctor f; |
4109 | myfunctor f; |
4055 | |
4110 | |
4056 | ev::io w; |
4111 | ev::io w; |
4057 | w.set (&f); |
4112 | w.set (&f); |
4058 | |
4113 | |
… | |
… | |
4076 | Associates a different C<struct ev_loop> with this watcher. You can only |
4131 | Associates a different C<struct ev_loop> with this watcher. You can only |
4077 | do this when the watcher is inactive (and not pending either). |
4132 | do this when the watcher is inactive (and not pending either). |
4078 | |
4133 | |
4079 | =item w->set ([arguments]) |
4134 | =item w->set ([arguments]) |
4080 | |
4135 | |
4081 | Basically the same as C<ev_TYPE_set>, with the same arguments. Either this |
4136 | Basically the same as C<ev_TYPE_set> (except for C<ev::embed> watchers>), |
4082 | method or a suitable start method must be called at least once. Unlike the |
4137 | with the same arguments. Either this method or a suitable start method |
4083 | C counterpart, an active watcher gets automatically stopped and restarted |
4138 | must be called at least once. Unlike the C counterpart, an active watcher |
4084 | when reconfiguring it with this method. |
4139 | gets automatically stopped and restarted when reconfiguring it with this |
|
|
4140 | method. |
|
|
4141 | |
|
|
4142 | For C<ev::embed> watchers this method is called C<set_embed>, to avoid |
|
|
4143 | clashing with the C<set (loop)> method. |
4085 | |
4144 | |
4086 | =item w->start () |
4145 | =item w->start () |
4087 | |
4146 | |
4088 | Starts the watcher. Note that there is no C<loop> argument, as the |
4147 | Starts the watcher. Note that there is no C<loop> argument, as the |
4089 | constructor already stores the event loop. |
4148 | constructor already stores the event loop. |
… | |
… | |
4192 | =item Lua |
4251 | =item Lua |
4193 | |
4252 | |
4194 | Brian Maher has written a partial interface to libev for lua (at the |
4253 | Brian Maher has written a partial interface to libev for lua (at the |
4195 | time of this writing, only C<ev_io> and C<ev_timer>), to be found at |
4254 | time of this writing, only C<ev_io> and C<ev_timer>), to be found at |
4196 | L<http://github.com/brimworks/lua-ev>. |
4255 | L<http://github.com/brimworks/lua-ev>. |
|
|
4256 | |
|
|
4257 | =item Javascript |
|
|
4258 | |
|
|
4259 | Node.js (L<http://nodejs.org>) uses libev as the underlying event library. |
|
|
4260 | |
|
|
4261 | =item Others |
|
|
4262 | |
|
|
4263 | There are others, and I stopped counting. |
4197 | |
4264 | |
4198 | =back |
4265 | =back |
4199 | |
4266 | |
4200 | |
4267 | |
4201 | =head1 MACRO MAGIC |
4268 | =head1 MACRO MAGIC |
… | |
… | |
4500 | |
4567 | |
4501 | If programs implement their own fd to handle mapping on win32, then this |
4568 | If programs implement their own fd to handle mapping on win32, then this |
4502 | macro can be used to override the C<close> function, useful to unregister |
4569 | macro can be used to override the C<close> function, useful to unregister |
4503 | file descriptors again. Note that the replacement function has to close |
4570 | file descriptors again. Note that the replacement function has to close |
4504 | the underlying OS handle. |
4571 | the underlying OS handle. |
|
|
4572 | |
|
|
4573 | =item EV_USE_WSASOCKET |
|
|
4574 | |
|
|
4575 | If defined to be C<1>, libev will use C<WSASocket> to create its internal |
|
|
4576 | communication socket, which works better in some environments. Otherwise, |
|
|
4577 | the normal C<socket> function will be used, which works better in other |
|
|
4578 | environments. |
4505 | |
4579 | |
4506 | =item EV_USE_POLL |
4580 | =item EV_USE_POLL |
4507 | |
4581 | |
4508 | If defined to be C<1>, libev will compile in support for the C<poll>(2) |
4582 | If defined to be C<1>, libev will compile in support for the C<poll>(2) |
4509 | backend. Otherwise it will be enabled on non-win32 platforms. It |
4583 | backend. Otherwise it will be enabled on non-win32 platforms. It |
… | |
… | |
4554 | different cpus (or different cpu cores). This reduces dependencies |
4628 | different cpus (or different cpu cores). This reduces dependencies |
4555 | and makes libev faster. |
4629 | and makes libev faster. |
4556 | |
4630 | |
4557 | =item EV_NO_THREADS |
4631 | =item EV_NO_THREADS |
4558 | |
4632 | |
4559 | If defined to be C<1>, libev will assume that it will never be called |
4633 | If defined to be C<1>, libev will assume that it will never be called from |
4560 | from different threads, which is a stronger assumption than C<EV_NO_SMP>, |
4634 | different threads (that includes signal handlers), which is a stronger |
4561 | above. This reduces dependencies and makes libev faster. |
4635 | assumption than C<EV_NO_SMP>, above. This reduces dependencies and makes |
|
|
4636 | libev faster. |
4562 | |
4637 | |
4563 | =item EV_ATOMIC_T |
4638 | =item EV_ATOMIC_T |
4564 | |
4639 | |
4565 | Libev requires an integer type (suitable for storing C<0> or C<1>) whose |
4640 | Libev requires an integer type (suitable for storing C<0> or C<1>) whose |
4566 | access is atomic and serialised with respect to other threads or signal |
4641 | access is atomic with respect to other threads or signal contexts. No |
4567 | contexts. No such type is easily found in the C language, so you can |
4642 | such type is easily found in the C language, so you can provide your own |
4568 | provide your own type that you know is safe for your purposes. It is used |
4643 | type that you know is safe for your purposes. It is used both for signal |
4569 | both for signal handler "locking" as well as for signal and thread safety |
4644 | handler "locking" as well as for signal and thread safety in C<ev_async> |
4570 | in C<ev_async> watchers. |
4645 | watchers. |
4571 | |
4646 | |
4572 | In the absence of this define, libev will use C<sig_atomic_t volatile> |
4647 | In the absence of this define, libev will use C<sig_atomic_t volatile> |
4573 | (from F<signal.h>), which is usually good enough on most platforms, |
4648 | (from F<signal.h>), which is usually good enough on most platforms. |
4574 | although strictly speaking using a type that also implies a memory fence |
|
|
4575 | is required. |
|
|
4576 | |
4649 | |
4577 | =item EV_H (h) |
4650 | =item EV_H (h) |
4578 | |
4651 | |
4579 | The name of the F<ev.h> header file used to include it. The default if |
4652 | The name of the F<ev.h> header file used to include it. The default if |
4580 | undefined is C<"ev.h"> in F<event.h>, F<ev.c> and F<ev++.h>. This can be |
4653 | undefined is C<"ev.h"> in F<event.h>, F<ev.c> and F<ev++.h>. This can be |
… | |
… | |
4948 | default loop and triggering an C<ev_async> watcher from the default loop |
5021 | default loop and triggering an C<ev_async> watcher from the default loop |
4949 | watcher callback into the event loop interested in the signal. |
5022 | watcher callback into the event loop interested in the signal. |
4950 | |
5023 | |
4951 | =back |
5024 | =back |
4952 | |
5025 | |
4953 | See also L<THREAD LOCKING EXAMPLE>. |
5026 | See also L</THREAD LOCKING EXAMPLE>. |
4954 | |
5027 | |
4955 | =head3 COROUTINES |
5028 | =head3 COROUTINES |
4956 | |
5029 | |
4957 | Libev is very accommodating to coroutines ("cooperative threads"): |
5030 | Libev is very accommodating to coroutines ("cooperative threads"): |
4958 | libev fully supports nesting calls to its functions from different |
5031 | libev fully supports nesting calls to its functions from different |
… | |
… | |
5227 | structure (guaranteed by POSIX but not by ISO C for example), but it also |
5300 | structure (guaranteed by POSIX but not by ISO C for example), but it also |
5228 | assumes that the same (machine) code can be used to call any watcher |
5301 | assumes that the same (machine) code can be used to call any watcher |
5229 | callback: The watcher callbacks have different type signatures, but libev |
5302 | callback: The watcher callbacks have different type signatures, but libev |
5230 | calls them using an C<ev_watcher *> internally. |
5303 | calls them using an C<ev_watcher *> internally. |
5231 | |
5304 | |
|
|
5305 | =item null pointers and integer zero are represented by 0 bytes |
|
|
5306 | |
|
|
5307 | Libev uses C<memset> to initialise structs and arrays to C<0> bytes, and |
|
|
5308 | relies on this setting pointers and integers to null. |
|
|
5309 | |
5232 | =item pointer accesses must be thread-atomic |
5310 | =item pointer accesses must be thread-atomic |
5233 | |
5311 | |
5234 | Accessing a pointer value must be atomic, it must both be readable and |
5312 | Accessing a pointer value must be atomic, it must both be readable and |
5235 | writable in one piece - this is the case on all current architectures. |
5313 | writable in one piece - this is the case on all current architectures. |
5236 | |
5314 | |
… | |
… | |
5249 | thread" or will block signals process-wide, both behaviours would |
5327 | thread" or will block signals process-wide, both behaviours would |
5250 | be compatible with libev. Interaction between C<sigprocmask> and |
5328 | be compatible with libev. Interaction between C<sigprocmask> and |
5251 | C<pthread_sigmask> could complicate things, however. |
5329 | C<pthread_sigmask> could complicate things, however. |
5252 | |
5330 | |
5253 | The most portable way to handle signals is to block signals in all threads |
5331 | The most portable way to handle signals is to block signals in all threads |
5254 | except the initial one, and run the default loop in the initial thread as |
5332 | except the initial one, and run the signal handling loop in the initial |
5255 | well. |
5333 | thread as well. |
5256 | |
5334 | |
5257 | =item C<long> must be large enough for common memory allocation sizes |
5335 | =item C<long> must be large enough for common memory allocation sizes |
5258 | |
5336 | |
5259 | To improve portability and simplify its API, libev uses C<long> internally |
5337 | To improve portability and simplify its API, libev uses C<long> internally |
5260 | instead of C<size_t> when allocating its data structures. On non-POSIX |
5338 | instead of C<size_t> when allocating its data structures. On non-POSIX |
… | |
… | |
5364 | =over 4 |
5442 | =over 4 |
5365 | |
5443 | |
5366 | =item C<EV_COMPAT3> backwards compatibility mechanism |
5444 | =item C<EV_COMPAT3> backwards compatibility mechanism |
5367 | |
5445 | |
5368 | The backward compatibility mechanism can be controlled by |
5446 | The backward compatibility mechanism can be controlled by |
5369 | C<EV_COMPAT3>. See L<PREPROCESSOR SYMBOLS/MACROS> in the L<EMBEDDING> |
5447 | C<EV_COMPAT3>. See L</"PREPROCESSOR SYMBOLS/MACROS"> in the L</EMBEDDING> |
5370 | section. |
5448 | section. |
5371 | |
5449 | |
5372 | =item C<ev_default_destroy> and C<ev_default_fork> have been removed |
5450 | =item C<ev_default_destroy> and C<ev_default_fork> have been removed |
5373 | |
5451 | |
5374 | These calls can be replaced easily by their C<ev_loop_xxx> counterparts: |
5452 | These calls can be replaced easily by their C<ev_loop_xxx> counterparts: |
… | |
… | |
5417 | =over 4 |
5495 | =over 4 |
5418 | |
5496 | |
5419 | =item active |
5497 | =item active |
5420 | |
5498 | |
5421 | A watcher is active as long as it has been started and not yet stopped. |
5499 | A watcher is active as long as it has been started and not yet stopped. |
5422 | See L<WATCHER STATES> for details. |
5500 | See L</WATCHER STATES> for details. |
5423 | |
5501 | |
5424 | =item application |
5502 | =item application |
5425 | |
5503 | |
5426 | In this document, an application is whatever is using libev. |
5504 | In this document, an application is whatever is using libev. |
5427 | |
5505 | |
… | |
… | |
5463 | watchers and events. |
5541 | watchers and events. |
5464 | |
5542 | |
5465 | =item pending |
5543 | =item pending |
5466 | |
5544 | |
5467 | A watcher is pending as soon as the corresponding event has been |
5545 | A watcher is pending as soon as the corresponding event has been |
5468 | detected. See L<WATCHER STATES> for details. |
5546 | detected. See L</WATCHER STATES> for details. |
5469 | |
5547 | |
5470 | =item real time |
5548 | =item real time |
5471 | |
5549 | |
5472 | The physical time that is observed. It is apparently strictly monotonic :) |
5550 | The physical time that is observed. It is apparently strictly monotonic :) |
5473 | |
5551 | |