ViewVC Help
View File | Revision Log | Show Annotations | Download File
/cvs/libev/ev.pod
(Generate patch)

Comparing libev/ev.pod (file contents):
Revision 1.272 by root, Tue Nov 24 06:39:28 2009 UTC vs.
Revision 1.276 by root, Tue Dec 29 13:11:00 2009 UTC

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
792 792
793Ref/unref can be used to add or remove a reference count on the event 793Ref/unref can be used to add or remove a reference count on the event
794loop: Every watcher keeps one reference, and as long as the reference 794loop: Every watcher keeps one reference, and as long as the reference
795count is nonzero, C<ev_loop> will not return on its own. 795count is nonzero, C<ev_loop> will not return on its own.
796 796
797If you have a watcher you never unregister that should not keep C<ev_loop> 797This is useful when you have a watcher that you never intend to
798from returning, call ev_unref() after starting, and ev_ref() before 798unregister, but that nevertheless should not keep C<ev_loop> from
799returning. In such a case, call C<ev_unref> after starting, and C<ev_ref>
799stopping it. 800before stopping it.
800 801
801As an example, libev itself uses this for its internal signal pipe: It 802As an example, libev itself uses this for its internal signal pipe: It
802is not visible to the libev user and should not keep C<ev_loop> from 803is not visible to the libev user and should not keep C<ev_loop> from
803exiting if no event watchers registered by it are active. It is also an 804exiting if no event watchers registered by it are active. It is also an
804excellent way to do this for generic recurring timers or from within 805excellent way to do this for generic recurring timers or from within
919 920
920While event loop modifications are allowed between invocations of 921While event loop modifications are allowed between invocations of
921C<release> and C<acquire> (that's their only purpose after all), no 922C<release> and C<acquire> (that's their only purpose after all), no
922modifications done will affect the event loop, i.e. adding watchers will 923modifications done will affect the event loop, i.e. adding watchers will
923have no effect on the set of file descriptors being watched, or the time 924have no effect on the set of file descriptors being watched, or the time
924waited. USe an C<ev_async> watcher to wake up C<ev_loop> when you want it 925waited. Use an C<ev_async> watcher to wake up C<ev_loop> when you want it
925to take note of any changes you made. 926to take note of any changes you made.
926 927
927In theory, threads executing C<ev_loop> will be async-cancel safe between 928In theory, threads executing C<ev_loop> will be async-cancel safe between
928invocations of C<release> and C<acquire>. 929invocations of C<release> and C<acquire>.
929 930
1126 1127
1127 ev_io w; 1128 ev_io w;
1128 ev_init (&w, my_cb); 1129 ev_init (&w, my_cb);
1129 ev_io_set (&w, STDIN_FILENO, EV_READ); 1130 ev_io_set (&w, STDIN_FILENO, EV_READ);
1130 1131
1131=item C<ev_TYPE_set> (ev_TYPE *, [args]) 1132=item C<ev_TYPE_set> (ev_TYPE *watcher, [args])
1132 1133
1133This macro initialises the type-specific parts of a watcher. You need to 1134This macro initialises the type-specific parts of a watcher. You need to
1134call C<ev_init> at least once before you call this macro, but you can 1135call C<ev_init> at least once before you call this macro, but you can
1135call C<ev_TYPE_set> any number of times. You must not, however, call this 1136call C<ev_TYPE_set> any number of times. You must not, however, call this
1136macro on a watcher that is active (it can be pending, however, which is a 1137macro on a watcher that is active (it can be pending, however, which is a
1149 1150
1150Example: Initialise and set an C<ev_io> watcher in one step. 1151Example: Initialise and set an C<ev_io> watcher in one step.
1151 1152
1152 ev_io_init (&w, my_cb, STDIN_FILENO, EV_READ); 1153 ev_io_init (&w, my_cb, STDIN_FILENO, EV_READ);
1153 1154
1154=item C<ev_TYPE_start> (loop *, ev_TYPE *watcher) 1155=item C<ev_TYPE_start> (loop, ev_TYPE *watcher)
1155 1156
1156Starts (activates) the given watcher. Only active watchers will receive 1157Starts (activates) the given watcher. Only active watchers will receive
1157events. If the watcher is already active nothing will happen. 1158events. If the watcher is already active nothing will happen.
1158 1159
1159Example: Start the C<ev_io> watcher that is being abused as example in this 1160Example: Start the C<ev_io> watcher that is being abused as example in this
1160whole section. 1161whole section.
1161 1162
1162 ev_io_start (EV_DEFAULT_UC, &w); 1163 ev_io_start (EV_DEFAULT_UC, &w);
1163 1164
1164=item C<ev_TYPE_stop> (loop *, ev_TYPE *watcher) 1165=item C<ev_TYPE_stop> (loop, ev_TYPE *watcher)
1165 1166
1166Stops the given watcher if active, and clears the pending status (whether 1167Stops the given watcher if active, and clears the pending status (whether
1167the watcher was active or not). 1168the watcher was active or not).
1168 1169
1169It is possible that stopped watchers are pending - for example, 1170It is possible that stopped watchers are pending - for example,
1194=item ev_cb_set (ev_TYPE *watcher, callback) 1195=item ev_cb_set (ev_TYPE *watcher, callback)
1195 1196
1196Change the callback. You can change the callback at virtually any time 1197Change the callback. You can change the callback at virtually any time
1197(modulo threads). 1198(modulo threads).
1198 1199
1199=item ev_set_priority (ev_TYPE *watcher, priority) 1200=item ev_set_priority (ev_TYPE *watcher, int priority)
1200 1201
1201=item int ev_priority (ev_TYPE *watcher) 1202=item int ev_priority (ev_TYPE *watcher)
1202 1203
1203Set and query the priority of the watcher. The priority is a small 1204Set and query the priority of the watcher. The priority is a small
1204integer between C<EV_MAXPRI> (default: C<2>) and C<EV_MINPRI> 1205integer between C<EV_MAXPRI> (default: C<2>) and C<EV_MINPRI>
1235returns its C<revents> bitset (as if its callback was invoked). If the 1236returns its C<revents> bitset (as if its callback was invoked). If the
1236watcher isn't pending it does nothing and returns C<0>. 1237watcher isn't pending it does nothing and returns C<0>.
1237 1238
1238Sometimes it can be useful to "poll" a watcher instead of waiting for its 1239Sometimes it can be useful to "poll" a watcher instead of waiting for its
1239callback to be invoked, which can be accomplished with this function. 1240callback to be invoked, which can be accomplished with this function.
1241
1242=item ev_feed_event (loop, ev_TYPE *watcher, int revents)
1243
1244Feeds the given event set into the event loop, as if the specified event
1245had happened for the specified watcher (which must be a pointer to an
1246initialised but not necessarily started event watcher). Obviously you must
1247not free the watcher as long as it has pending events.
1248
1249Stopping the watcher, letting libev invoke it, or calling
1250C<ev_clear_pending> will clear the pending event, even if the watcher was
1251not started in the first place.
1252
1253See also C<ev_feed_fd_event> and C<ev_feed_signal_event> for related
1254functions that do not need a watcher.
1240 1255
1241=back 1256=back
1242 1257
1243 1258
1244=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER 1259=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER
1840C<repeat> value), or reset the running timer to the C<repeat> value. 1855C<repeat> value), or reset the running timer to the C<repeat> value.
1841 1856
1842This sounds a bit complicated, see L<Be smart about timeouts>, above, for a 1857This sounds a bit complicated, see L<Be smart about timeouts>, above, for a
1843usage example. 1858usage example.
1844 1859
1845=item ev_timer_remaining (loop, ev_timer *) 1860=item ev_tstamp ev_timer_remaining (loop, ev_timer *)
1846 1861
1847Returns the remaining time until a timer fires. If the timer is active, 1862Returns the remaining time until a timer fires. If the timer is active,
1848then this time is relative to the current event loop time, otherwise it's 1863then this time is relative to the current event loop time, otherwise it's
1849the timeout value currently configured. 1864the timeout value currently configured.
1850 1865
2967=head3 Queueing 2982=head3 Queueing
2968 2983
2969C<ev_async> does not support queueing of data in any way. The reason 2984C<ev_async> does not support queueing of data in any way. The reason
2970is that the author does not know of a simple (or any) algorithm for a 2985is that the author does not know of a simple (or any) algorithm for a
2971multiple-writer-single-reader queue that works in all cases and doesn't 2986multiple-writer-single-reader queue that works in all cases and doesn't
2972need elaborate support such as pthreads. 2987need elaborate support such as pthreads or unportable memory access
2988semantics.
2973 2989
2974That means that if you want to queue data, you have to provide your own 2990That means that if you want to queue data, you have to provide your own
2975queue. But at least I can tell you how to implement locking around your 2991queue. But at least I can tell you how to implement locking around your
2976queue: 2992queue:
2977 2993
3135 /* doh, nothing entered */; 3151 /* doh, nothing entered */;
3136 } 3152 }
3137 3153
3138 ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); 3154 ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);
3139 3155
3140=item ev_feed_event (struct ev_loop *, watcher *, int revents)
3141
3142Feeds the given event set into the event loop, as if the specified event
3143had happened for the specified watcher (which must be a pointer to an
3144initialised but not necessarily started event watcher).
3145
3146=item ev_feed_fd_event (struct ev_loop *, int fd, int revents) 3156=item ev_feed_fd_event (loop, int fd, int revents)
3147 3157
3148Feed an event on the given fd, as if a file descriptor backend detected 3158Feed an event on the given fd, as if a file descriptor backend detected
3149the given events it. 3159the given events it.
3150 3160
3151=item ev_feed_signal_event (struct ev_loop *loop, int signum) 3161=item ev_feed_signal_event (loop, int signum)
3152 3162
3153Feed an event as if the given signal occurred (C<loop> must be the default 3163Feed an event as if the given signal occurred (C<loop> must be the default
3154loop!). 3164loop!).
3155 3165
3156=back 3166=back
3236 3246
3237=over 4 3247=over 4
3238 3248
3239=item ev::TYPE::TYPE () 3249=item ev::TYPE::TYPE ()
3240 3250
3241=item ev::TYPE::TYPE (struct ev_loop *) 3251=item ev::TYPE::TYPE (loop)
3242 3252
3243=item ev::TYPE::~TYPE 3253=item ev::TYPE::~TYPE
3244 3254
3245The constructor (optionally) takes an event loop to associate the watcher 3255The constructor (optionally) takes an event loop to associate the watcher
3246with. If it is omitted, it will use C<EV_DEFAULT>. 3256with. If it is omitted, it will use C<EV_DEFAULT>.
3323Example: Use a plain function as callback. 3333Example: Use a plain function as callback.
3324 3334
3325 static void io_cb (ev::io &w, int revents) { } 3335 static void io_cb (ev::io &w, int revents) { }
3326 iow.set <io_cb> (); 3336 iow.set <io_cb> ();
3327 3337
3328=item w->set (struct ev_loop *) 3338=item w->set (loop)
3329 3339
3330Associates a different C<struct ev_loop> with this watcher. You can only 3340Associates a different C<struct ev_loop> with this watcher. You can only
3331do this when the watcher is inactive (and not pending either). 3341do this when the watcher is inactive (and not pending either).
3332 3342
3333=item w->set ([arguments]) 3343=item w->set ([arguments])

Diff Legend

Removed lines
+ Added lines
< Changed lines
> Changed lines