… | |
… | |
118 | Libev is very configurable. In this manual the default (and most common) |
118 | Libev is very configurable. In this manual the default (and most common) |
119 | configuration will be described, which supports multiple event loops. For |
119 | configuration will be described, which supports multiple event loops. For |
120 | more info about various configuration options please have a look at |
120 | more info about various configuration options please have a look at |
121 | B<EMBED> section in this manual. If libev was configured without support |
121 | B<EMBED> section in this manual. If libev was configured without support |
122 | for multiple event loops, then all functions taking an initial argument of |
122 | for multiple event loops, then all functions taking an initial argument of |
123 | name C<loop> (which is always of type C<ev_loop *>) will not have |
123 | name C<loop> (which is always of type C<struct ev_loop *>) will not have |
124 | this argument. |
124 | this argument. |
125 | |
125 | |
126 | =head2 TIME REPRESENTATION |
126 | =head2 TIME REPRESENTATION |
127 | |
127 | |
128 | Libev represents time as a single floating point number, representing |
128 | Libev represents time as a single floating point number, representing |
… | |
… | |
370 | When this flag is specified, then libev will not attempt to use the |
370 | When this flag is specified, then libev will not attempt to use the |
371 | I<inotify> API for it's C<ev_stat> watchers. Apart from debugging and |
371 | I<inotify> API for it's C<ev_stat> watchers. Apart from debugging and |
372 | testing, this flag can be useful to conserve inotify file descriptors, as |
372 | testing, this flag can be useful to conserve inotify file descriptors, as |
373 | otherwise each loop using C<ev_stat> watchers consumes one inotify handle. |
373 | otherwise each loop using C<ev_stat> watchers consumes one inotify handle. |
374 | |
374 | |
375 | =item C<EVFLAG_NOSIGNALFD> |
375 | =item C<EVFLAG_SIGNALFD> |
376 | |
376 | |
377 | When this flag is specified, then libev will not attempt to use the |
377 | When this flag is specified, then libev will attempt to use the |
378 | I<signalfd> API for it's C<ev_signal> (and C<ev_child>) watchers. This is |
378 | I<signalfd> API for it's C<ev_signal> (and C<ev_child>) watchers. This API |
379 | probably only useful to work around any bugs in libev. Consequently, this |
379 | delivers signals synchronously, which makes it both faster and might make |
380 | flag might go away once the signalfd functionality is considered stable, |
380 | it possible to get the queued signal data. It can also simplify signal |
381 | so it's useful mostly in environment variables and not in program code. |
381 | handling with threads, as long as you properly block signals in your |
|
|
382 | threads that are not interested in handling them. |
|
|
383 | |
|
|
384 | Signalfd will not be used by default as this changes your signal mask, and |
|
|
385 | there are a lot of shoddy libraries and programs (glib's threadpool for |
|
|
386 | example) that can't properly initialise their signal masks. |
382 | |
387 | |
383 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
388 | =item C<EVBACKEND_SELECT> (value 1, portable select backend) |
384 | |
389 | |
385 | This is your standard select(2) backend. Not I<completely> standard, as |
390 | This is your standard select(2) backend. Not I<completely> standard, as |
386 | libev tries to roll its own fd_set with no limits on the number of fds, |
391 | libev tries to roll its own fd_set with no limits on the number of fds, |
… | |
… | |
410 | |
415 | |
411 | This backend maps C<EV_READ> to C<POLLIN | POLLERR | POLLHUP>, and |
416 | This backend maps C<EV_READ> to C<POLLIN | POLLERR | POLLHUP>, and |
412 | C<EV_WRITE> to C<POLLOUT | POLLERR | POLLHUP>. |
417 | C<EV_WRITE> to C<POLLOUT | POLLERR | POLLHUP>. |
413 | |
418 | |
414 | =item C<EVBACKEND_EPOLL> (value 4, Linux) |
419 | =item C<EVBACKEND_EPOLL> (value 4, Linux) |
|
|
420 | |
|
|
421 | Use the linux-specific epoll(7) interface (for both pre- and post-2.6.9 |
|
|
422 | kernels). |
415 | |
423 | |
416 | For few fds, this backend is a bit little slower than poll and select, |
424 | For few fds, this backend is a bit little slower than poll and select, |
417 | but it scales phenomenally better. While poll and select usually scale |
425 | but it scales phenomenally better. While poll and select usually scale |
418 | like O(total_fds) where n is the total number of fds (or the highest fd), |
426 | like O(total_fds) where n is the total number of fds (or the highest fd), |
419 | epoll scales either O(1) or O(active_fds). |
427 | epoll scales either O(1) or O(active_fds). |
… | |
… | |
590 | as signal and child watchers) would need to be stopped manually. |
598 | as signal and child watchers) would need to be stopped manually. |
591 | |
599 | |
592 | In general it is not advisable to call this function except in the |
600 | In general it is not advisable to call this function except in the |
593 | rare occasion where you really need to free e.g. the signal handling |
601 | rare occasion where you really need to free e.g. the signal handling |
594 | pipe fds. If you need dynamically allocated loops it is better to use |
602 | pipe fds. If you need dynamically allocated loops it is better to use |
595 | C<ev_loop_new> and C<ev_loop_destroy>). |
603 | C<ev_loop_new> and C<ev_loop_destroy>. |
596 | |
604 | |
597 | =item ev_loop_destroy (loop) |
605 | =item ev_loop_destroy (loop) |
598 | |
606 | |
599 | Like C<ev_default_destroy>, but destroys an event loop created by an |
607 | Like C<ev_default_destroy>, but destroys an event loop created by an |
600 | earlier call to C<ev_loop_new>. |
608 | earlier call to C<ev_loop_new>. |
… | |
… | |
704 | event loop time (see C<ev_now_update>). |
712 | event loop time (see C<ev_now_update>). |
705 | |
713 | |
706 | =item ev_loop (loop, int flags) |
714 | =item ev_loop (loop, int flags) |
707 | |
715 | |
708 | Finally, this is it, the event handler. This function usually is called |
716 | Finally, this is it, the event handler. This function usually is called |
709 | after you initialised all your watchers and you want to start handling |
717 | after you have initialised all your watchers and you want to start |
710 | events. |
718 | handling events. |
711 | |
719 | |
712 | If the flags argument is specified as C<0>, it will not return until |
720 | If the flags argument is specified as C<0>, it will not return until |
713 | either no event watchers are active anymore or C<ev_unloop> was called. |
721 | either no event watchers are active anymore or C<ev_unloop> was called. |
714 | |
722 | |
715 | Please note that an explicit C<ev_unloop> is usually better than |
723 | Please note that an explicit C<ev_unloop> is usually better than |
… | |
… | |
789 | |
797 | |
790 | Ref/unref can be used to add or remove a reference count on the event |
798 | Ref/unref can be used to add or remove a reference count on the event |
791 | loop: Every watcher keeps one reference, and as long as the reference |
799 | loop: Every watcher keeps one reference, and as long as the reference |
792 | count is nonzero, C<ev_loop> will not return on its own. |
800 | count is nonzero, C<ev_loop> will not return on its own. |
793 | |
801 | |
794 | If you have a watcher you never unregister that should not keep C<ev_loop> |
802 | This is useful when you have a watcher that you never intend to |
795 | from returning, call ev_unref() after starting, and ev_ref() before |
803 | unregister, but that nevertheless should not keep C<ev_loop> from |
|
|
804 | returning. In such a case, call C<ev_unref> after starting, and C<ev_ref> |
796 | stopping it. |
805 | before stopping it. |
797 | |
806 | |
798 | As an example, libev itself uses this for its internal signal pipe: It |
807 | As an example, libev itself uses this for its internal signal pipe: It |
799 | is not visible to the libev user and should not keep C<ev_loop> from |
808 | is not visible to the libev user and should not keep C<ev_loop> from |
800 | exiting if no event watchers registered by it are active. It is also an |
809 | exiting if no event watchers registered by it are active. It is also an |
801 | excellent way to do this for generic recurring timers or from within |
810 | excellent way to do this for generic recurring timers or from within |
… | |
… | |
916 | |
925 | |
917 | While event loop modifications are allowed between invocations of |
926 | While event loop modifications are allowed between invocations of |
918 | C<release> and C<acquire> (that's their only purpose after all), no |
927 | C<release> and C<acquire> (that's their only purpose after all), no |
919 | modifications done will affect the event loop, i.e. adding watchers will |
928 | modifications done will affect the event loop, i.e. adding watchers will |
920 | have no effect on the set of file descriptors being watched, or the time |
929 | have no effect on the set of file descriptors being watched, or the time |
921 | waited. USe an C<ev_async> watcher to wake up C<ev_loop> when you want it |
930 | waited. Use an C<ev_async> watcher to wake up C<ev_loop> when you want it |
922 | to take note of any changes you made. |
931 | to take note of any changes you made. |
923 | |
932 | |
924 | In theory, threads executing C<ev_loop> will be async-cancel safe between |
933 | In theory, threads executing C<ev_loop> will be async-cancel safe between |
925 | invocations of C<release> and C<acquire>. |
934 | invocations of C<release> and C<acquire>. |
926 | |
935 | |
… | |
… | |
1123 | |
1132 | |
1124 | ev_io w; |
1133 | ev_io w; |
1125 | ev_init (&w, my_cb); |
1134 | ev_init (&w, my_cb); |
1126 | ev_io_set (&w, STDIN_FILENO, EV_READ); |
1135 | ev_io_set (&w, STDIN_FILENO, EV_READ); |
1127 | |
1136 | |
1128 | =item C<ev_TYPE_set> (ev_TYPE *, [args]) |
1137 | =item C<ev_TYPE_set> (ev_TYPE *watcher, [args]) |
1129 | |
1138 | |
1130 | This macro initialises the type-specific parts of a watcher. You need to |
1139 | This macro initialises the type-specific parts of a watcher. You need to |
1131 | call C<ev_init> at least once before you call this macro, but you can |
1140 | call C<ev_init> at least once before you call this macro, but you can |
1132 | call C<ev_TYPE_set> any number of times. You must not, however, call this |
1141 | call C<ev_TYPE_set> any number of times. You must not, however, call this |
1133 | macro on a watcher that is active (it can be pending, however, which is a |
1142 | macro on a watcher that is active (it can be pending, however, which is a |
… | |
… | |
1146 | |
1155 | |
1147 | Example: Initialise and set an C<ev_io> watcher in one step. |
1156 | Example: Initialise and set an C<ev_io> watcher in one step. |
1148 | |
1157 | |
1149 | ev_io_init (&w, my_cb, STDIN_FILENO, EV_READ); |
1158 | ev_io_init (&w, my_cb, STDIN_FILENO, EV_READ); |
1150 | |
1159 | |
1151 | =item C<ev_TYPE_start> (loop *, ev_TYPE *watcher) |
1160 | =item C<ev_TYPE_start> (loop, ev_TYPE *watcher) |
1152 | |
1161 | |
1153 | Starts (activates) the given watcher. Only active watchers will receive |
1162 | Starts (activates) the given watcher. Only active watchers will receive |
1154 | events. If the watcher is already active nothing will happen. |
1163 | events. If the watcher is already active nothing will happen. |
1155 | |
1164 | |
1156 | Example: Start the C<ev_io> watcher that is being abused as example in this |
1165 | Example: Start the C<ev_io> watcher that is being abused as example in this |
1157 | whole section. |
1166 | whole section. |
1158 | |
1167 | |
1159 | ev_io_start (EV_DEFAULT_UC, &w); |
1168 | ev_io_start (EV_DEFAULT_UC, &w); |
1160 | |
1169 | |
1161 | =item C<ev_TYPE_stop> (loop *, ev_TYPE *watcher) |
1170 | =item C<ev_TYPE_stop> (loop, ev_TYPE *watcher) |
1162 | |
1171 | |
1163 | Stops the given watcher if active, and clears the pending status (whether |
1172 | Stops the given watcher if active, and clears the pending status (whether |
1164 | the watcher was active or not). |
1173 | the watcher was active or not). |
1165 | |
1174 | |
1166 | It is possible that stopped watchers are pending - for example, |
1175 | It is possible that stopped watchers are pending - for example, |
… | |
… | |
1191 | =item ev_cb_set (ev_TYPE *watcher, callback) |
1200 | =item ev_cb_set (ev_TYPE *watcher, callback) |
1192 | |
1201 | |
1193 | Change the callback. You can change the callback at virtually any time |
1202 | Change the callback. You can change the callback at virtually any time |
1194 | (modulo threads). |
1203 | (modulo threads). |
1195 | |
1204 | |
1196 | =item ev_set_priority (ev_TYPE *watcher, priority) |
1205 | =item ev_set_priority (ev_TYPE *watcher, int priority) |
1197 | |
1206 | |
1198 | =item int ev_priority (ev_TYPE *watcher) |
1207 | =item int ev_priority (ev_TYPE *watcher) |
1199 | |
1208 | |
1200 | Set and query the priority of the watcher. The priority is a small |
1209 | Set and query the priority of the watcher. The priority is a small |
1201 | integer between C<EV_MAXPRI> (default: C<2>) and C<EV_MINPRI> |
1210 | integer between C<EV_MAXPRI> (default: C<2>) and C<EV_MINPRI> |
… | |
… | |
1232 | returns its C<revents> bitset (as if its callback was invoked). If the |
1241 | returns its C<revents> bitset (as if its callback was invoked). If the |
1233 | watcher isn't pending it does nothing and returns C<0>. |
1242 | watcher isn't pending it does nothing and returns C<0>. |
1234 | |
1243 | |
1235 | Sometimes it can be useful to "poll" a watcher instead of waiting for its |
1244 | Sometimes it can be useful to "poll" a watcher instead of waiting for its |
1236 | callback to be invoked, which can be accomplished with this function. |
1245 | callback to be invoked, which can be accomplished with this function. |
|
|
1246 | |
|
|
1247 | =item ev_feed_event (loop, ev_TYPE *watcher, int revents) |
|
|
1248 | |
|
|
1249 | Feeds the given event set into the event loop, as if the specified event |
|
|
1250 | had happened for the specified watcher (which must be a pointer to an |
|
|
1251 | initialised but not necessarily started event watcher). Obviously you must |
|
|
1252 | not free the watcher as long as it has pending events. |
|
|
1253 | |
|
|
1254 | Stopping the watcher, letting libev invoke it, or calling |
|
|
1255 | C<ev_clear_pending> will clear the pending event, even if the watcher was |
|
|
1256 | not started in the first place. |
|
|
1257 | |
|
|
1258 | See also C<ev_feed_fd_event> and C<ev_feed_signal_event> for related |
|
|
1259 | functions that do not need a watcher. |
1237 | |
1260 | |
1238 | =back |
1261 | =back |
1239 | |
1262 | |
1240 | |
1263 | |
1241 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
1264 | =head2 ASSOCIATING CUSTOM DATA WITH A WATCHER |
… | |
… | |
1837 | C<repeat> value), or reset the running timer to the C<repeat> value. |
1860 | C<repeat> value), or reset the running timer to the C<repeat> value. |
1838 | |
1861 | |
1839 | This sounds a bit complicated, see L<Be smart about timeouts>, above, for a |
1862 | This sounds a bit complicated, see L<Be smart about timeouts>, above, for a |
1840 | usage example. |
1863 | usage example. |
1841 | |
1864 | |
1842 | =item ev_timer_remaining (loop, ev_timer *) |
1865 | =item ev_tstamp ev_timer_remaining (loop, ev_timer *) |
1843 | |
1866 | |
1844 | Returns the remaining time until a timer fires. If the timer is active, |
1867 | Returns the remaining time until a timer fires. If the timer is active, |
1845 | then this time is relative to the current event loop time, otherwise it's |
1868 | then this time is relative to the current event loop time, otherwise it's |
1846 | the timeout value currently configured. |
1869 | the timeout value currently configured. |
1847 | |
1870 | |
… | |
… | |
2114 | C<SA_RESTART> (or equivalent) behaviour enabled, so system calls should |
2137 | C<SA_RESTART> (or equivalent) behaviour enabled, so system calls should |
2115 | not be unduly interrupted. If you have a problem with system calls getting |
2138 | not be unduly interrupted. If you have a problem with system calls getting |
2116 | interrupted by signals you can block all signals in an C<ev_check> watcher |
2139 | interrupted by signals you can block all signals in an C<ev_check> watcher |
2117 | and unblock them in an C<ev_prepare> watcher. |
2140 | and unblock them in an C<ev_prepare> watcher. |
2118 | |
2141 | |
2119 | =head3 The special problem of inheritance over execve |
2142 | =head3 The special problem of inheritance over fork/execve/pthread_create |
2120 | |
2143 | |
2121 | Both the signal mask (C<sigprocmask>) and the signal disposition |
2144 | Both the signal mask (C<sigprocmask>) and the signal disposition |
2122 | (C<sigaction>) are unspecified after starting a signal watcher (and after |
2145 | (C<sigaction>) are unspecified after starting a signal watcher (and after |
2123 | stopping it again), that is, libev might or might not block the signal, |
2146 | stopping it again), that is, libev might or might not block the signal, |
2124 | and might or might not set or restore the installed signal handler. |
2147 | and might or might not set or restore the installed signal handler. |
2125 | |
2148 | |
2126 | While this does not matter for the signal disposition (libev never |
2149 | While this does not matter for the signal disposition (libev never |
2127 | sets signals to C<SIG_IGN>, so handlers will be reset to C<SIG_DFL> on |
2150 | sets signals to C<SIG_IGN>, so handlers will be reset to C<SIG_DFL> on |
2128 | C<execve>), this matters for the signal mask: many programs do not expect |
2151 | C<execve>), this matters for the signal mask: many programs do not expect |
2129 | many signals to be blocked. |
2152 | certain signals to be blocked. |
2130 | |
2153 | |
2131 | This means that before calling C<exec> (from the child) you should reset |
2154 | This means that before calling C<exec> (from the child) you should reset |
2132 | the signal mask to whatever "default" you expect (all clear is a good |
2155 | the signal mask to whatever "default" you expect (all clear is a good |
2133 | choice usually). |
2156 | choice usually). |
|
|
2157 | |
|
|
2158 | The simplest way to ensure that the signal mask is reset in the child is |
|
|
2159 | to install a fork handler with C<pthread_atfork> that resets it. That will |
|
|
2160 | catch fork calls done by libraries (such as the libc) as well. |
|
|
2161 | |
|
|
2162 | In current versions of libev, the signal will not be blocked indefinitely |
|
|
2163 | unless you use the C<signalfd> API (C<EV_SIGNALFD>). While this reduces |
|
|
2164 | the window of opportunity for problems, it will not go away, as libev |
|
|
2165 | I<has> to modify the signal mask, at least temporarily. |
|
|
2166 | |
|
|
2167 | So I can't stress this enough: I<If you do not reset your signal mask when |
|
|
2168 | you expect it to be empty, you have a race condition in your code>. This |
|
|
2169 | is not a libev-specific thing, this is true for most event libraries. |
2134 | |
2170 | |
2135 | =head3 Watcher-Specific Functions and Data Members |
2171 | =head3 Watcher-Specific Functions and Data Members |
2136 | |
2172 | |
2137 | =over 4 |
2173 | =over 4 |
2138 | |
2174 | |
… | |
… | |
2955 | =head3 Queueing |
2991 | =head3 Queueing |
2956 | |
2992 | |
2957 | C<ev_async> does not support queueing of data in any way. The reason |
2993 | C<ev_async> does not support queueing of data in any way. The reason |
2958 | is that the author does not know of a simple (or any) algorithm for a |
2994 | is that the author does not know of a simple (or any) algorithm for a |
2959 | multiple-writer-single-reader queue that works in all cases and doesn't |
2995 | multiple-writer-single-reader queue that works in all cases and doesn't |
2960 | need elaborate support such as pthreads. |
2996 | need elaborate support such as pthreads or unportable memory access |
|
|
2997 | semantics. |
2961 | |
2998 | |
2962 | That means that if you want to queue data, you have to provide your own |
2999 | That means that if you want to queue data, you have to provide your own |
2963 | queue. But at least I can tell you how to implement locking around your |
3000 | queue. But at least I can tell you how to implement locking around your |
2964 | queue: |
3001 | queue: |
2965 | |
3002 | |
… | |
… | |
3123 | /* doh, nothing entered */; |
3160 | /* doh, nothing entered */; |
3124 | } |
3161 | } |
3125 | |
3162 | |
3126 | ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
3163 | ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); |
3127 | |
3164 | |
3128 | =item ev_feed_event (struct ev_loop *, watcher *, int revents) |
|
|
3129 | |
|
|
3130 | Feeds the given event set into the event loop, as if the specified event |
|
|
3131 | had happened for the specified watcher (which must be a pointer to an |
|
|
3132 | initialised but not necessarily started event watcher). |
|
|
3133 | |
|
|
3134 | =item ev_feed_fd_event (struct ev_loop *, int fd, int revents) |
3165 | =item ev_feed_fd_event (loop, int fd, int revents) |
3135 | |
3166 | |
3136 | Feed an event on the given fd, as if a file descriptor backend detected |
3167 | Feed an event on the given fd, as if a file descriptor backend detected |
3137 | the given events it. |
3168 | the given events it. |
3138 | |
3169 | |
3139 | =item ev_feed_signal_event (struct ev_loop *loop, int signum) |
3170 | =item ev_feed_signal_event (loop, int signum) |
3140 | |
3171 | |
3141 | Feed an event as if the given signal occurred (C<loop> must be the default |
3172 | Feed an event as if the given signal occurred (C<loop> must be the default |
3142 | loop!). |
3173 | loop!). |
3143 | |
3174 | |
3144 | =back |
3175 | =back |
… | |
… | |
3224 | |
3255 | |
3225 | =over 4 |
3256 | =over 4 |
3226 | |
3257 | |
3227 | =item ev::TYPE::TYPE () |
3258 | =item ev::TYPE::TYPE () |
3228 | |
3259 | |
3229 | =item ev::TYPE::TYPE (struct ev_loop *) |
3260 | =item ev::TYPE::TYPE (loop) |
3230 | |
3261 | |
3231 | =item ev::TYPE::~TYPE |
3262 | =item ev::TYPE::~TYPE |
3232 | |
3263 | |
3233 | The constructor (optionally) takes an event loop to associate the watcher |
3264 | The constructor (optionally) takes an event loop to associate the watcher |
3234 | with. If it is omitted, it will use C<EV_DEFAULT>. |
3265 | with. If it is omitted, it will use C<EV_DEFAULT>. |
… | |
… | |
3311 | Example: Use a plain function as callback. |
3342 | Example: Use a plain function as callback. |
3312 | |
3343 | |
3313 | static void io_cb (ev::io &w, int revents) { } |
3344 | static void io_cb (ev::io &w, int revents) { } |
3314 | iow.set <io_cb> (); |
3345 | iow.set <io_cb> (); |
3315 | |
3346 | |
3316 | =item w->set (struct ev_loop *) |
3347 | =item w->set (loop) |
3317 | |
3348 | |
3318 | Associates a different C<struct ev_loop> with this watcher. You can only |
3349 | Associates a different C<struct ev_loop> with this watcher. You can only |
3319 | do this when the watcher is inactive (and not pending either). |
3350 | do this when the watcher is inactive (and not pending either). |
3320 | |
3351 | |
3321 | =item w->set ([arguments]) |
3352 | =item w->set ([arguments]) |
… | |
… | |
3420 | Erkki Seppala has written Ocaml bindings for libev, to be found at |
3451 | Erkki Seppala has written Ocaml bindings for libev, to be found at |
3421 | L<http://modeemi.cs.tut.fi/~flux/software/ocaml-ev/>. |
3452 | L<http://modeemi.cs.tut.fi/~flux/software/ocaml-ev/>. |
3422 | |
3453 | |
3423 | =item Lua |
3454 | =item Lua |
3424 | |
3455 | |
3425 | Brian Maher has written a partial interface to libev |
3456 | Brian Maher has written a partial interface to libev for lua (at the |
3426 | for lua (only C<ev_io> and C<ev_timer>), to be found at |
3457 | time of this writing, only C<ev_io> and C<ev_timer>), to be found at |
3427 | L<http://github.com/brimworks/lua-ev>. |
3458 | L<http://github.com/brimworks/lua-ev>. |
3428 | |
3459 | |
3429 | =back |
3460 | =back |
3430 | |
3461 | |
3431 | |
3462 | |