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118Libev is very configurable. In this manual the default (and most common) 118Libev is very configurable. In this manual the default (and most common)
119configuration will be described, which supports multiple event loops. For 119configuration will be described, which supports multiple event loops. For
120more info about various configuration options please have a look at 120more info about various configuration options please have a look at
121B<EMBED> section in this manual. If libev was configured without support 121B<EMBED> section in this manual. If libev was configured without support
122for multiple event loops, then all functions taking an initial argument of 122for multiple event loops, then all functions taking an initial argument of
123name C<loop> (which is always of type C<ev_loop *>) will not have 123name C<loop> (which is always of type C<struct ev_loop *>) will not have
124this argument. 124this argument.
125 125
126=head2 TIME REPRESENTATION 126=head2 TIME REPRESENTATION
127 127
128Libev represents time as a single floating point number, representing 128Libev represents time as a single floating point number, representing
370When this flag is specified, then libev will not attempt to use the 370When this flag is specified, then libev will not attempt to use the
371I<inotify> API for it's C<ev_stat> watchers. Apart from debugging and 371I<inotify> API for it's C<ev_stat> watchers. Apart from debugging and
372testing, this flag can be useful to conserve inotify file descriptors, as 372testing, this flag can be useful to conserve inotify file descriptors, as
373otherwise each loop using C<ev_stat> watchers consumes one inotify handle. 373otherwise each loop using C<ev_stat> watchers consumes one inotify handle.
374 374
375=item C<EVFLAG_NOSIGNALFD> 375=item C<EVFLAG_NOSIGFD>
376 376
377When this flag is specified, then libev will not attempt to use the 377When this flag is specified, then libev will not attempt to use the
378I<signalfd> API for it's C<ev_signal> (and C<ev_child>) watchers. This is 378I<signalfd> API for it's C<ev_signal> (and C<ev_child>) watchers. This is
379probably only useful to work around any bugs in libev. Consequently, this 379probably only useful to work around any bugs in libev. Consequently, this
380flag might go away once the signalfd functionality is considered stable, 380flag might go away once the signalfd functionality is considered stable,
410 410
411This backend maps C<EV_READ> to C<POLLIN | POLLERR | POLLHUP>, and 411This backend maps C<EV_READ> to C<POLLIN | POLLERR | POLLHUP>, and
412C<EV_WRITE> to C<POLLOUT | POLLERR | POLLHUP>. 412C<EV_WRITE> to C<POLLOUT | POLLERR | POLLHUP>.
413 413
414=item C<EVBACKEND_EPOLL> (value 4, Linux) 414=item C<EVBACKEND_EPOLL> (value 4, Linux)
415
416Use the linux-specific epoll(7) interface (for both pre- and post-2.6.9
417kernels).
415 418
416For few fds, this backend is a bit little slower than poll and select, 419For few fds, this backend is a bit little slower than poll and select,
417but it scales phenomenally better. While poll and select usually scale 420but it scales phenomenally better. While poll and select usually scale
418like O(total_fds) where n is the total number of fds (or the highest fd), 421like O(total_fds) where n is the total number of fds (or the highest fd),
419epoll scales either O(1) or O(active_fds). 422epoll scales either O(1) or O(active_fds).
590as signal and child watchers) would need to be stopped manually. 593as signal and child watchers) would need to be stopped manually.
591 594
592In general it is not advisable to call this function except in the 595In general it is not advisable to call this function except in the
593rare occasion where you really need to free e.g. the signal handling 596rare occasion where you really need to free e.g. the signal handling
594pipe fds. If you need dynamically allocated loops it is better to use 597pipe fds. If you need dynamically allocated loops it is better to use
595C<ev_loop_new> and C<ev_loop_destroy>). 598C<ev_loop_new> and C<ev_loop_destroy>.
596 599
597=item ev_loop_destroy (loop) 600=item ev_loop_destroy (loop)
598 601
599Like C<ev_default_destroy>, but destroys an event loop created by an 602Like C<ev_default_destroy>, but destroys an event loop created by an
600earlier call to C<ev_loop_new>. 603earlier call to C<ev_loop_new>.
704event loop time (see C<ev_now_update>). 707event loop time (see C<ev_now_update>).
705 708
706=item ev_loop (loop, int flags) 709=item ev_loop (loop, int flags)
707 710
708Finally, this is it, the event handler. This function usually is called 711Finally, this is it, the event handler. This function usually is called
709after you initialised all your watchers and you want to start handling 712after you have initialised all your watchers and you want to start
710events. 713handling events.
711 714
712If the flags argument is specified as C<0>, it will not return until 715If the flags argument is specified as C<0>, it will not return until
713either no event watchers are active anymore or C<ev_unloop> was called. 716either no event watchers are active anymore or C<ev_unloop> was called.
714 717
715Please note that an explicit C<ev_unloop> is usually better than 718Please note that an explicit C<ev_unloop> is usually better than
916 919
917While event loop modifications are allowed between invocations of 920While event loop modifications are allowed between invocations of
918C<release> and C<acquire> (that's their only purpose after all), no 921C<release> and C<acquire> (that's their only purpose after all), no
919modifications done will affect the event loop, i.e. adding watchers will 922modifications done will affect the event loop, i.e. adding watchers will
920have no effect on the set of file descriptors being watched, or the time 923have no effect on the set of file descriptors being watched, or the time
921waited. USe an C<ev_async> watcher to wake up C<ev_loop> when you want it 924waited. Use an C<ev_async> watcher to wake up C<ev_loop> when you want it
922to take note of any changes you made. 925to take note of any changes you made.
923 926
924In theory, threads executing C<ev_loop> will be async-cancel safe between 927In theory, threads executing C<ev_loop> will be async-cancel safe between
925invocations of C<release> and C<acquire>. 928invocations of C<release> and C<acquire>.
926 929
1123 1126
1124 ev_io w; 1127 ev_io w;
1125 ev_init (&w, my_cb); 1128 ev_init (&w, my_cb);
1126 ev_io_set (&w, STDIN_FILENO, EV_READ); 1129 ev_io_set (&w, STDIN_FILENO, EV_READ);
1127 1130
1128=item C<ev_TYPE_set> (ev_TYPE *, [args]) 1131=item C<ev_TYPE_set> (ev_TYPE *watcher, [args])
1129 1132
1130This macro initialises the type-specific parts of a watcher. You need to 1133This macro initialises the type-specific parts of a watcher. You need to
1131call C<ev_init> at least once before you call this macro, but you can 1134call C<ev_init> at least once before you call this macro, but you can
1132call C<ev_TYPE_set> any number of times. You must not, however, call this 1135call C<ev_TYPE_set> any number of times. You must not, however, call this
1133macro on a watcher that is active (it can be pending, however, which is a 1136macro on a watcher that is active (it can be pending, however, which is a
1146 1149
1147Example: Initialise and set an C<ev_io> watcher in one step. 1150Example: Initialise and set an C<ev_io> watcher in one step.
1148 1151
1149 ev_io_init (&w, my_cb, STDIN_FILENO, EV_READ); 1152 ev_io_init (&w, my_cb, STDIN_FILENO, EV_READ);
1150 1153
1151=item C<ev_TYPE_start> (loop *, ev_TYPE *watcher) 1154=item C<ev_TYPE_start> (loop, ev_TYPE *watcher)
1152 1155
1153Starts (activates) the given watcher. Only active watchers will receive 1156Starts (activates) the given watcher. Only active watchers will receive
1154events. If the watcher is already active nothing will happen. 1157events. If the watcher is already active nothing will happen.
1155 1158
1156Example: Start the C<ev_io> watcher that is being abused as example in this 1159Example: Start the C<ev_io> watcher that is being abused as example in this
1157whole section. 1160whole section.
1158 1161
1159 ev_io_start (EV_DEFAULT_UC, &w); 1162 ev_io_start (EV_DEFAULT_UC, &w);
1160 1163
1161=item C<ev_TYPE_stop> (loop *, ev_TYPE *watcher) 1164=item C<ev_TYPE_stop> (loop, ev_TYPE *watcher)
1162 1165
1163Stops the given watcher if active, and clears the pending status (whether 1166Stops the given watcher if active, and clears the pending status (whether
1164the watcher was active or not). 1167the watcher was active or not).
1165 1168
1166It is possible that stopped watchers are pending - for example, 1169It is possible that stopped watchers are pending - for example,
1191=item ev_cb_set (ev_TYPE *watcher, callback) 1194=item ev_cb_set (ev_TYPE *watcher, callback)
1192 1195
1193Change the callback. You can change the callback at virtually any time 1196Change the callback. You can change the callback at virtually any time
1194(modulo threads). 1197(modulo threads).
1195 1198
1196=item ev_set_priority (ev_TYPE *watcher, priority) 1199=item ev_set_priority (ev_TYPE *watcher, int priority)
1197 1200
1198=item int ev_priority (ev_TYPE *watcher) 1201=item int ev_priority (ev_TYPE *watcher)
1199 1202
1200Set and query the priority of the watcher. The priority is a small 1203Set and query the priority of the watcher. The priority is a small
1201integer between C<EV_MAXPRI> (default: C<2>) and C<EV_MINPRI> 1204integer between C<EV_MAXPRI> (default: C<2>) and C<EV_MINPRI>
1232returns its C<revents> bitset (as if its callback was invoked). If the 1235returns its C<revents> bitset (as if its callback was invoked). If the
1233watcher isn't pending it does nothing and returns C<0>. 1236watcher isn't pending it does nothing and returns C<0>.
1234 1237
1235Sometimes it can be useful to "poll" a watcher instead of waiting for its 1238Sometimes it can be useful to "poll" a watcher instead of waiting for its
1236callback to be invoked, which can be accomplished with this function. 1239callback to be invoked, which can be accomplished with this function.
1240
1241=item ev_feed_event (loop, ev_TYPE *watcher, int revents)
1242
1243Feeds the given event set into the event loop, as if the specified event
1244had happened for the specified watcher (which must be a pointer to an
1245initialised but not necessarily started event watcher). Obviously you must
1246not free the watcher as long as it has pending events.
1247
1248Stopping the watcher, letting libev invoke it, or calling
1249C<ev_clear_pending> will clear the pending event, even if the watcher was
1250not started in the first place.
1251
1252See also C<ev_feed_fd_event> and C<ev_feed_signal_event> for related
1253functions that do not need a watcher.
1237 1254
1238=back 1255=back
1239 1256
1240 1257
1241=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER 1258=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER
1837C<repeat> value), or reset the running timer to the C<repeat> value. 1854C<repeat> value), or reset the running timer to the C<repeat> value.
1838 1855
1839This sounds a bit complicated, see L<Be smart about timeouts>, above, for a 1856This sounds a bit complicated, see L<Be smart about timeouts>, above, for a
1840usage example. 1857usage example.
1841 1858
1842=item ev_timer_remaining (loop, ev_timer *) 1859=item ev_tstamp ev_timer_remaining (loop, ev_timer *)
1843 1860
1844Returns the remaining time until a timer fires. If the timer is active, 1861Returns the remaining time until a timer fires. If the timer is active,
1845then this time is relative to the current event loop time, otherwise it's 1862then this time is relative to the current event loop time, otherwise it's
1846the timeout value currently configured. 1863the timeout value currently configured.
1847 1864
2130 2147
2131This means that before calling C<exec> (from the child) you should reset 2148This means that before calling C<exec> (from the child) you should reset
2132the signal mask to whatever "default" you expect (all clear is a good 2149the signal mask to whatever "default" you expect (all clear is a good
2133choice usually). 2150choice usually).
2134 2151
2152The simplest way to ensure that the signal mask is reset in the child is
2153to install a fork handler with C<pthread_atfork> that resets it. That will
2154catch fork calls done by libraries (such as the libc) as well.
2155
2135In current versions of libev, you can ensure that the signal mask is not 2156In current versions of libev, you can also ensure that the signal mask is
2136blocking any signals (except temporarily, so thread users watch out) by 2157not blocking any signals (except temporarily, so thread users watch out)
2137specifying the C<EVFLAG_NOSIGNALFD> when creating the event loop. This is 2158by specifying the C<EVFLAG_NOSIGFD> when creating the event loop. This
2138not guaranteed for future versions, however. 2159is not guaranteed for future versions, however.
2139 2160
2140=head3 Watcher-Specific Functions and Data Members 2161=head3 Watcher-Specific Functions and Data Members
2141 2162
2142=over 4 2163=over 4
2143 2164
2960=head3 Queueing 2981=head3 Queueing
2961 2982
2962C<ev_async> does not support queueing of data in any way. The reason 2983C<ev_async> does not support queueing of data in any way. The reason
2963is that the author does not know of a simple (or any) algorithm for a 2984is that the author does not know of a simple (or any) algorithm for a
2964multiple-writer-single-reader queue that works in all cases and doesn't 2985multiple-writer-single-reader queue that works in all cases and doesn't
2965need elaborate support such as pthreads. 2986need elaborate support such as pthreads or unportable memory access
2987semantics.
2966 2988
2967That means that if you want to queue data, you have to provide your own 2989That means that if you want to queue data, you have to provide your own
2968queue. But at least I can tell you how to implement locking around your 2990queue. But at least I can tell you how to implement locking around your
2969queue: 2991queue:
2970 2992
3128 /* doh, nothing entered */; 3150 /* doh, nothing entered */;
3129 } 3151 }
3130 3152
3131 ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); 3153 ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);
3132 3154
3133=item ev_feed_event (struct ev_loop *, watcher *, int revents)
3134
3135Feeds the given event set into the event loop, as if the specified event
3136had happened for the specified watcher (which must be a pointer to an
3137initialised but not necessarily started event watcher).
3138
3139=item ev_feed_fd_event (struct ev_loop *, int fd, int revents) 3155=item ev_feed_fd_event (loop, int fd, int revents)
3140 3156
3141Feed an event on the given fd, as if a file descriptor backend detected 3157Feed an event on the given fd, as if a file descriptor backend detected
3142the given events it. 3158the given events it.
3143 3159
3144=item ev_feed_signal_event (struct ev_loop *loop, int signum) 3160=item ev_feed_signal_event (loop, int signum)
3145 3161
3146Feed an event as if the given signal occurred (C<loop> must be the default 3162Feed an event as if the given signal occurred (C<loop> must be the default
3147loop!). 3163loop!).
3148 3164
3149=back 3165=back
3229 3245
3230=over 4 3246=over 4
3231 3247
3232=item ev::TYPE::TYPE () 3248=item ev::TYPE::TYPE ()
3233 3249
3234=item ev::TYPE::TYPE (struct ev_loop *) 3250=item ev::TYPE::TYPE (loop)
3235 3251
3236=item ev::TYPE::~TYPE 3252=item ev::TYPE::~TYPE
3237 3253
3238The constructor (optionally) takes an event loop to associate the watcher 3254The constructor (optionally) takes an event loop to associate the watcher
3239with. If it is omitted, it will use C<EV_DEFAULT>. 3255with. If it is omitted, it will use C<EV_DEFAULT>.
3316Example: Use a plain function as callback. 3332Example: Use a plain function as callback.
3317 3333
3318 static void io_cb (ev::io &w, int revents) { } 3334 static void io_cb (ev::io &w, int revents) { }
3319 iow.set <io_cb> (); 3335 iow.set <io_cb> ();
3320 3336
3321=item w->set (struct ev_loop *) 3337=item w->set (loop)
3322 3338
3323Associates a different C<struct ev_loop> with this watcher. You can only 3339Associates a different C<struct ev_loop> with this watcher. You can only
3324do this when the watcher is inactive (and not pending either). 3340do this when the watcher is inactive (and not pending either).
3325 3341
3326=item w->set ([arguments]) 3342=item w->set ([arguments])

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