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4<head> 4<head>
5 <title>libev</title> 5 <title>libev</title>
6 <meta name="description" content="Pod documentation for libev" /> 6 <meta name="description" content="Pod documentation for libev" />
7 <meta name="inputfile" content="&lt;standard input&gt;" /> 7 <meta name="inputfile" content="&lt;standard input&gt;" />
8 <meta name="outputfile" content="&lt;standard output&gt;" /> 8 <meta name="outputfile" content="&lt;standard output&gt;" />
9 <meta name="created" content="Fri Nov 23 17:17:04 2007" /> 9 <meta name="created" content="Sat Nov 24 10:48:32 2007" />
10 <meta name="generator" content="Pod::Xhtml 1.57" /> 10 <meta name="generator" content="Pod::Xhtml 1.57" />
11<link rel="stylesheet" href="http://res.tst.eu/pod.css"/></head> 11<link rel="stylesheet" href="http://res.tst.eu/pod.css"/></head>
12<body> 12<body>
13<div class="pod"> 13<div class="pod">
14<!-- INDEX START --> 14<!-- INDEX START -->
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21<li><a href="#CONVENTIONS">CONVENTIONS</a></li> 21<li><a href="#CONVENTIONS">CONVENTIONS</a></li>
22<li><a href="#TIME_REPRESENTATION">TIME REPRESENTATION</a></li> 22<li><a href="#TIME_REPRESENTATION">TIME REPRESENTATION</a></li>
23<li><a href="#GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</a></li> 23<li><a href="#GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</a></li>
24<li><a href="#FUNCTIONS_CONTROLLING_THE_EVENT_LOOP">FUNCTIONS CONTROLLING THE EVENT LOOP</a></li> 24<li><a href="#FUNCTIONS_CONTROLLING_THE_EVENT_LOOP">FUNCTIONS CONTROLLING THE EVENT LOOP</a></li>
25<li><a href="#ANATOMY_OF_A_WATCHER">ANATOMY OF A WATCHER</a> 25<li><a href="#ANATOMY_OF_A_WATCHER">ANATOMY OF A WATCHER</a>
26<ul><li><a href="#SUMMARY_OF_GENERIC_WATCHER_FUNCTIONS">SUMMARY OF GENERIC WATCHER FUNCTIONS</a></li>
26<ul><li><a href="#ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH">ASSOCIATING CUSTOM DATA WITH A WATCHER</a></li> 27<li><a href="#ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH">ASSOCIATING CUSTOM DATA WITH A WATCHER</a></li>
27</ul> 28</ul>
28</li> 29</li>
29<li><a href="#WATCHER_TYPES">WATCHER TYPES</a> 30<li><a href="#WATCHER_TYPES">WATCHER TYPES</a>
30<ul><li><a href="#code_ev_io_code_is_this_file_descrip"><code>ev_io</code> - is this file descriptor readable or writable</a></li> 31<ul><li><a href="#code_ev_io_code_is_this_file_descrip"><code>ev_io</code> - is this file descriptor readable or writable</a></li>
31<li><a href="#code_ev_timer_code_relative_and_opti"><code>ev_timer</code> - relative and optionally recurring timeouts</a></li> 32<li><a href="#code_ev_timer_code_relative_and_opti"><code>ev_timer</code> - relative and optionally recurring timeouts</a></li>
32<li><a href="#code_ev_periodic_code_to_cron_or_not"><code>ev_periodic</code> - to cron or not to cron</a></li> 33<li><a href="#code_ev_periodic_code_to_cron_or_not"><code>ev_periodic</code> - to cron or not to cron</a></li>
33<li><a href="#code_ev_signal_code_signal_me_when_a"><code>ev_signal</code> - signal me when a signal gets signalled</a></li> 34<li><a href="#code_ev_signal_code_signal_me_when_a"><code>ev_signal</code> - signal me when a signal gets signalled</a></li>
34<li><a href="#code_ev_child_code_wait_for_pid_stat"><code>ev_child</code> - wait for pid status changes</a></li> 35<li><a href="#code_ev_child_code_wait_for_pid_stat"><code>ev_child</code> - wait for pid status changes</a></li>
35<li><a href="#code_ev_idle_code_when_you_ve_got_no"><code>ev_idle</code> - when you've got nothing better to do</a></li> 36<li><a href="#code_ev_idle_code_when_you_ve_got_no"><code>ev_idle</code> - when you've got nothing better to do</a></li>
36<li><a href="#code_ev_prepare_code_and_code_ev_che"><code>ev_prepare</code> and <code>ev_check</code> - customise your event loop</a></li> 37<li><a href="#code_ev_prepare_code_and_code_ev_che"><code>ev_prepare</code> and <code>ev_check</code> - customise your event loop</a></li>
38<li><a href="#code_ev_embed_code_when_one_backend_"><code>ev_embed</code> - when one backend isn't enough</a></li>
37</ul> 39</ul>
38</li> 40</li>
39<li><a href="#OTHER_FUNCTIONS">OTHER FUNCTIONS</a></li> 41<li><a href="#OTHER_FUNCTIONS">OTHER FUNCTIONS</a></li>
40<li><a href="#LIBEVENT_EMULATION">LIBEVENT EMULATION</a></li> 42<li><a href="#LIBEVENT_EMULATION">LIBEVENT EMULATION</a></li>
41<li><a href="#C_SUPPORT">C++ SUPPORT</a></li> 43<li><a href="#C_SUPPORT">C++ SUPPORT</a></li>
… …
156recommended for this platform. This set is often smaller than the one 158recommended for this platform. This set is often smaller than the one
157returned by <code>ev_supported_backends</code>, as for example kqueue is broken on 159returned by <code>ev_supported_backends</code>, as for example kqueue is broken on
158most BSDs and will not be autodetected unless you explicitly request it 160most BSDs and will not be autodetected unless you explicitly request it
159(assuming you know what you are doing). This is the set of backends that 161(assuming you know what you are doing). This is the set of backends that
160libev will probe for if you specify no backends explicitly.</p> 162libev will probe for if you specify no backends explicitly.</p>
163 </dd>
164 <dt>unsigned int ev_embeddable_backends ()</dt>
165 <dd>
166 <p>Returns the set of backends that are embeddable in other event loops. This
167is the theoretical, all-platform, value. To find which backends
168might be supported on the current system, you would need to look at
169<code>ev_embeddable_backends () &amp; ev_supported_backends ()</code>, likewise for
170recommended ones.</p>
171 <p>See the description of <code>ev_embed</code> watchers for more info.</p>
161 </dd> 172 </dd>
162 <dt>ev_set_allocator (void *(*cb)(void *ptr, long size))</dt> 173 <dt>ev_set_allocator (void *(*cb)(void *ptr, long size))</dt>
163 <dd> 174 <dd>
164 <p>Sets the allocation function to use (the prototype is similar to the 175 <p>Sets the allocation function to use (the prototype is similar to the
165realloc C function, the semantics are identical). It is used to allocate 176realloc C function, the semantics are identical). It is used to allocate
… …
353</pre> 364</pre>
354 </dd> 365 </dd>
355 <dt>ev_default_destroy ()</dt> 366 <dt>ev_default_destroy ()</dt>
356 <dd> 367 <dd>
357 <p>Destroys the default loop again (frees all memory and kernel state 368 <p>Destroys the default loop again (frees all memory and kernel state
358etc.). This stops all registered event watchers (by not touching them in 369etc.). None of the active event watchers will be stopped in the normal
359any way whatsoever, although you cannot rely on this :).</p> 370sense, so e.g. <code>ev_is_active</code> might still return true. It is your
371responsibility to either stop all watchers cleanly yoursef <i>before</i>
372calling this function, or cope with the fact afterwards (which is usually
373the easiest thing, youc na just ignore the watchers and/or <code>free ()</code> them
374for example).</p>
360 </dd> 375 </dd>
361 <dt>ev_loop_destroy (loop)</dt> 376 <dt>ev_loop_destroy (loop)</dt>
362 <dd> 377 <dd>
363 <p>Like <code>ev_default_destroy</code>, but destroys an event loop created by an 378 <p>Like <code>ev_default_destroy</code>, but destroys an event loop created by an
364earlier call to <code>ev_loop_new</code>.</p> 379earlier call to <code>ev_loop_new</code>.</p>
… …
525with a watcher-specific start function (<code>ev_&lt;type&gt;_start (loop, watcher 540with a watcher-specific start function (<code>ev_&lt;type&gt;_start (loop, watcher
526*)</code>), and you can stop watching for events at any time by calling the 541*)</code>), and you can stop watching for events at any time by calling the
527corresponding stop function (<code>ev_&lt;type&gt;_stop (loop, watcher *)</code>.</p> 542corresponding stop function (<code>ev_&lt;type&gt;_stop (loop, watcher *)</code>.</p>
528<p>As long as your watcher is active (has been started but not stopped) you 543<p>As long as your watcher is active (has been started but not stopped) you
529must not touch the values stored in it. Most specifically you must never 544must not touch the values stored in it. Most specifically you must never
530reinitialise it or call its set macro.</p> 545reinitialise it or call its <code>set</code> macro.</p>
531<p>You can check whether an event is active by calling the <code>ev_is_active
532(watcher *)</code> macro. To see whether an event is outstanding (but the
533callback for it has not been called yet) you can use the <code>ev_is_pending
534(watcher *)</code> macro.</p>
535<p>Each and every callback receives the event loop pointer as first, the 546<p>Each and every callback receives the event loop pointer as first, the
536registered watcher structure as second, and a bitset of received events as 547registered watcher structure as second, and a bitset of received events as
537third argument.</p> 548third argument.</p>
538<p>The received events usually include a single bit per event type received 549<p>The received events usually include a single bit per event type received
539(you can receive multiple events at the same time). The possible bit masks 550(you can receive multiple events at the same time). The possible bit masks
… …
588your callbacks is well-written it can just attempt the operation and cope 599your callbacks is well-written it can just attempt the operation and cope
589with the error from read() or write(). This will not work in multithreaded 600with the error from read() or write(). This will not work in multithreaded
590programs, though, so beware.</p> 601programs, though, so beware.</p>
591 </dd> 602 </dd>
592</dl> 603</dl>
604
605</div>
606<h2 id="SUMMARY_OF_GENERIC_WATCHER_FUNCTIONS">SUMMARY OF GENERIC WATCHER FUNCTIONS</h2>
607<div id="SUMMARY_OF_GENERIC_WATCHER_FUNCTIONS-2">
608<p>In the following description, <code>TYPE</code> stands for the watcher type,
609e.g. <code>timer</code> for <code>ev_timer</code> watchers and <code>io</code> for <code>ev_io</code> watchers.</p>
610<dl>
611 <dt><code>ev_init</code> (ev_TYPE *watcher, callback)</dt>
612 <dd>
613 <p>This macro initialises the generic portion of a watcher. The contents
614of the watcher object can be arbitrary (so <code>malloc</code> will do). Only
615the generic parts of the watcher are initialised, you <i>need</i> to call
616the type-specific <code>ev_TYPE_set</code> macro afterwards to initialise the
617type-specific parts. For each type there is also a <code>ev_TYPE_init</code> macro
618which rolls both calls into one.</p>
619 <p>You can reinitialise a watcher at any time as long as it has been stopped
620(or never started) and there are no pending events outstanding.</p>
621 <p>The callbakc is always of type <code>void (*)(ev_loop *loop, ev_TYPE *watcher,
622int revents)</code>.</p>
623 </dd>
624 <dt><code>ev_TYPE_set</code> (ev_TYPE *, [args])</dt>
625 <dd>
626 <p>This macro initialises the type-specific parts of a watcher. You need to
627call <code>ev_init</code> at least once before you call this macro, but you can
628call <code>ev_TYPE_set</code> any number of times. You must not, however, call this
629macro on a watcher that is active (it can be pending, however, which is a
630difference to the <code>ev_init</code> macro).</p>
631 <p>Although some watcher types do not have type-specific arguments
632(e.g. <code>ev_prepare</code>) you still need to call its <code>set</code> macro.</p>
633 </dd>
634 <dt><code>ev_TYPE_init</code> (ev_TYPE *watcher, callback, [args])</dt>
635 <dd>
636 <p>This convinience macro rolls both <code>ev_init</code> and <code>ev_TYPE_set</code> macro
637calls into a single call. This is the most convinient method to initialise
638a watcher. The same limitations apply, of course.</p>
639 </dd>
640 <dt><code>ev_TYPE_start</code> (loop *, ev_TYPE *watcher)</dt>
641 <dd>
642 <p>Starts (activates) the given watcher. Only active watchers will receive
643events. If the watcher is already active nothing will happen.</p>
644 </dd>
645 <dt><code>ev_TYPE_stop</code> (loop *, ev_TYPE *watcher)</dt>
646 <dd>
647 <p>Stops the given watcher again (if active) and clears the pending
648status. It is possible that stopped watchers are pending (for example,
649non-repeating timers are being stopped when they become pending), but
650<code>ev_TYPE_stop</code> ensures that the watcher is neither active nor pending. If
651you want to free or reuse the memory used by the watcher it is therefore a
652good idea to always call its <code>ev_TYPE_stop</code> function.</p>
653 </dd>
654 <dt>bool ev_is_active (ev_TYPE *watcher)</dt>
655 <dd>
656 <p>Returns a true value iff the watcher is active (i.e. it has been started
657and not yet been stopped). As long as a watcher is active you must not modify
658it.</p>
659 </dd>
660 <dt>bool ev_is_pending (ev_TYPE *watcher)</dt>
661 <dd>
662 <p>Returns a true value iff the watcher is pending, (i.e. it has outstanding
663events but its callback has not yet been invoked). As long as a watcher
664is pending (but not active) you must not call an init function on it (but
665<code>ev_TYPE_set</code> is safe) and you must make sure the watcher is available to
666libev (e.g. you cnanot <code>free ()</code> it).</p>
667 </dd>
668 <dt>callback = ev_cb (ev_TYPE *watcher)</dt>
669 <dd>
670 <p>Returns the callback currently set on the watcher.</p>
671 </dd>
672 <dt>ev_cb_set (ev_TYPE *watcher, callback)</dt>
673 <dd>
674 <p>Change the callback. You can change the callback at virtually any time
675(modulo threads).</p>
676 </dd>
677</dl>
678
679
680
681
593 682
594</div> 683</div>
595<h2 id="ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH">ASSOCIATING CUSTOM DATA WITH A WATCHER</h2> 684<h2 id="ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH">ASSOCIATING CUSTOM DATA WITH A WATCHER</h2>
596<div id="ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH-2"> 685<div id="ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH-2">
597<p>Each watcher has, by default, a member <code>void *data</code> that you can change 686<p>Each watcher has, by default, a member <code>void *data</code> that you can change
… …
788<p>Periodic watchers are also timers of a kind, but they are very versatile 877<p>Periodic watchers are also timers of a kind, but they are very versatile
789(and unfortunately a bit complex).</p> 878(and unfortunately a bit complex).</p>
790<p>Unlike <code>ev_timer</code>'s, they are not based on real time (or relative time) 879<p>Unlike <code>ev_timer</code>'s, they are not based on real time (or relative time)
791but on wallclock time (absolute time). You can tell a periodic watcher 880but on wallclock time (absolute time). You can tell a periodic watcher
792to trigger &quot;at&quot; some specific point in time. For example, if you tell a 881to trigger &quot;at&quot; some specific point in time. For example, if you tell a
793periodic watcher to trigger in 10 seconds (by specifiying e.g. c&lt;ev_now () 882periodic watcher to trigger in 10 seconds (by specifiying e.g. <code>ev_now ()
794+ 10.&gt;) and then reset your system clock to the last year, then it will 883+ 10.</code>) and then reset your system clock to the last year, then it will
795take a year to trigger the event (unlike an <code>ev_timer</code>, which would trigger 884take a year to trigger the event (unlike an <code>ev_timer</code>, which would trigger
796roughly 10 seconds later and of course not if you reset your system time 885roughly 10 seconds later and of course not if you reset your system time
797again).</p> 886again).</p>
798<p>They can also be used to implement vastly more complex timers, such as 887<p>They can also be used to implement vastly more complex timers, such as
799triggering an event on eahc midnight, local time.</p> 888triggering an event on eahc midnight, local time.</p>
… …
930 <dd> 1019 <dd>
931 <p>Configures the watcher to trigger on the given signal number (usually one 1020 <p>Configures the watcher to trigger on the given signal number (usually one
932of the <code>SIGxxx</code> constants).</p> 1021of the <code>SIGxxx</code> constants).</p>
933 </dd> 1022 </dd>
934</dl> 1023</dl>
1024
1025
1026
1027
935 1028
936</div> 1029</div>
937<h2 id="code_ev_child_code_wait_for_pid_stat"><code>ev_child</code> - wait for pid status changes</h2> 1030<h2 id="code_ev_child_code_wait_for_pid_stat"><code>ev_child</code> - wait for pid status changes</h2>
938<div id="code_ev_child_code_wait_for_pid_stat-2"> 1031<div id="code_ev_child_code_wait_for_pid_stat-2">
939<p>Child watchers trigger when your process receives a SIGCHLD in response to 1032<p>Child watchers trigger when your process receives a SIGCHLD in response to
… …
1013<h2 id="code_ev_prepare_code_and_code_ev_che"><code>ev_prepare</code> and <code>ev_check</code> - customise your event loop</h2> 1106<h2 id="code_ev_prepare_code_and_code_ev_che"><code>ev_prepare</code> and <code>ev_check</code> - customise your event loop</h2>
1014<div id="code_ev_prepare_code_and_code_ev_che-2"> 1107<div id="code_ev_prepare_code_and_code_ev_che-2">
1015<p>Prepare and check watchers are usually (but not always) used in tandem: 1108<p>Prepare and check watchers are usually (but not always) used in tandem:
1016prepare watchers get invoked before the process blocks and check watchers 1109prepare watchers get invoked before the process blocks and check watchers
1017afterwards.</p> 1110afterwards.</p>
1018<p>Their main purpose is to integrate other event mechanisms into libev. This 1111<p>Their main purpose is to integrate other event mechanisms into libev and
1019could be used, for example, to track variable changes, implement your own 1112their use is somewhat advanced. This could be used, for example, to track
1020watchers, integrate net-snmp or a coroutine library and lots more.</p> 1113variable changes, implement your own watchers, integrate net-snmp or a
1114coroutine library and lots more.</p>
1021<p>This is done by examining in each prepare call which file descriptors need 1115<p>This is done by examining in each prepare call which file descriptors need
1022to be watched by the other library, registering <code>ev_io</code> watchers for 1116to be watched by the other library, registering <code>ev_io</code> watchers for
1023them and starting an <code>ev_timer</code> watcher for any timeouts (many libraries 1117them and starting an <code>ev_timer</code> watcher for any timeouts (many libraries
1024provide just this functionality). Then, in the check watcher you check for 1118provide just this functionality). Then, in the check watcher you check for
1025any events that occured (by checking the pending status of all watchers 1119any events that occured (by checking the pending status of all watchers
… …
1042parameters of any kind. There are <code>ev_prepare_set</code> and <code>ev_check_set</code> 1136parameters of any kind. There are <code>ev_prepare_set</code> and <code>ev_check_set</code>
1043macros, but using them is utterly, utterly and completely pointless.</p> 1137macros, but using them is utterly, utterly and completely pointless.</p>
1044 </dd> 1138 </dd>
1045</dl> 1139</dl>
1046<p>Example: *TODO*.</p> 1140<p>Example: *TODO*.</p>
1141
1142
1143
1144
1145
1146</div>
1147<h2 id="code_ev_embed_code_when_one_backend_"><code>ev_embed</code> - when one backend isn't enough</h2>
1148<div id="code_ev_embed_code_when_one_backend_-2">
1149<p>This is a rather advanced watcher type that lets you embed one event loop
1150into another (currently only <code>ev_io</code> events are supported in the embedded
1151loop, other types of watchers might be handled in a delayed or incorrect
1152fashion and must not be used).</p>
1153<p>There are primarily two reasons you would want that: work around bugs and
1154prioritise I/O.</p>
1155<p>As an example for a bug workaround, the kqueue backend might only support
1156sockets on some platform, so it is unusable as generic backend, but you
1157still want to make use of it because you have many sockets and it scales
1158so nicely. In this case, you would create a kqueue-based loop and embed it
1159into your default loop (which might use e.g. poll). Overall operation will
1160be a bit slower because first libev has to poll and then call kevent, but
1161at least you can use both at what they are best.</p>
1162<p>As for prioritising I/O: rarely you have the case where some fds have
1163to be watched and handled very quickly (with low latency), and even
1164priorities and idle watchers might have too much overhead. In this case
1165you would put all the high priority stuff in one loop and all the rest in
1166a second one, and embed the second one in the first.</p>
1167<p>As long as the watcher is active, the callback will be invoked every time
1168there might be events pending in the embedded loop. The callback must then
1169call <code>ev_embed_sweep (mainloop, watcher)</code> to make a single sweep and invoke
1170their callbacks (you could also start an idle watcher to give the embedded
1171loop strictly lower priority for example). You can also set the callback
1172to <code>0</code>, in which case the embed watcher will automatically execute the
1173embedded loop sweep.</p>
1174<p>As long as the watcher is started it will automatically handle events. The
1175callback will be invoked whenever some events have been handled. You can
1176set the callback to <code>0</code> to avoid having to specify one if you are not
1177interested in that.</p>
1178<p>Also, there have not currently been made special provisions for forking:
1179when you fork, you not only have to call <code>ev_loop_fork</code> on both loops,
1180but you will also have to stop and restart any <code>ev_embed</code> watchers
1181yourself.</p>
1182<p>Unfortunately, not all backends are embeddable, only the ones returned by
1183<code>ev_embeddable_backends</code> are, which, unfortunately, does not include any
1184portable one.</p>
1185<p>So when you want to use this feature you will always have to be prepared
1186that you cannot get an embeddable loop. The recommended way to get around
1187this is to have a separate variables for your embeddable loop, try to
1188create it, and if that fails, use the normal loop for everything:</p>
1189<pre> struct ev_loop *loop_hi = ev_default_init (0);
1190 struct ev_loop *loop_lo = 0;
1191 struct ev_embed embed;
1192
1193 // see if there is a chance of getting one that works
1194 // (remember that a flags value of 0 means autodetection)
1195 loop_lo = ev_embeddable_backends () &amp; ev_recommended_backends ()
1196 ? ev_loop_new (ev_embeddable_backends () &amp; ev_recommended_backends ())
1197 : 0;
1198
1199 // if we got one, then embed it, otherwise default to loop_hi
1200 if (loop_lo)
1201 {
1202 ev_embed_init (&amp;embed, 0, loop_lo);
1203 ev_embed_start (loop_hi, &amp;embed);
1204 }
1205 else
1206 loop_lo = loop_hi;
1207
1208</pre>
1209<dl>
1210 <dt>ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)</dt>
1211 <dt>ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)</dt>
1212 <dd>
1213 <p>Configures the watcher to embed the given loop, which must be
1214embeddable. If the callback is <code>0</code>, then <code>ev_embed_sweep</code> will be
1215invoked automatically, otherwise it is the responsibility of the callback
1216to invoke it (it will continue to be called until the sweep has been done,
1217if you do not want thta, you need to temporarily stop the embed watcher).</p>
1218 </dd>
1219 <dt>ev_embed_sweep (loop, ev_embed *)</dt>
1220 <dd>
1221 <p>Make a single, non-blocking sweep over the embedded loop. This works
1222similarly to <code>ev_loop (embedded_loop, EVLOOP_NONBLOCK)</code>, but in the most
1223apropriate way for embedded loops.</p>
1224 </dd>
1225</dl>
1047 1226
1048 1227
1049 1228
1050 1229
1051 1230
… …
1082 1261
1083 ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); 1262 ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);
1084 1263
1085</pre> 1264</pre>
1086 </dd> 1265 </dd>
1087 <dt>ev_feed_event (loop, watcher, int events)</dt> 1266 <dt>ev_feed_event (ev_loop *, watcher *, int revents)</dt>
1088 <dd> 1267 <dd>
1089 <p>Feeds the given event set into the event loop, as if the specified event 1268 <p>Feeds the given event set into the event loop, as if the specified event
1090had happened for the specified watcher (which must be a pointer to an 1269had happened for the specified watcher (which must be a pointer to an
1091initialised but not necessarily started event watcher).</p> 1270initialised but not necessarily started event watcher).</p>
1092 </dd> 1271 </dd>
1093 <dt>ev_feed_fd_event (loop, int fd, int revents)</dt> 1272 <dt>ev_feed_fd_event (ev_loop *, int fd, int revents)</dt>
1094 <dd> 1273 <dd>
1095 <p>Feed an event on the given fd, as if a file descriptor backend detected 1274 <p>Feed an event on the given fd, as if a file descriptor backend detected
1096the given events it.</p> 1275the given events it.</p>
1097 </dd> 1276 </dd>
1098 <dt>ev_feed_signal_event (loop, int signum)</dt> 1277 <dt>ev_feed_signal_event (ev_loop *loop, int signum)</dt>
1099 <dd> 1278 <dd>
1100 <p>Feed an event as if the given signal occured (loop must be the default loop!).</p> 1279 <p>Feed an event as if the given signal occured (<code>loop</code> must be the default
1280loop!).</p>
1101 </dd> 1281 </dd>
1102</dl> 1282</dl>
1103 1283
1104 1284
1105 1285
… …
1126</dl> 1306</dl>
1127 1307
1128</div> 1308</div>
1129<h1 id="C_SUPPORT">C++ SUPPORT</h1><p><a href="#TOP" class="toplink">Top</a></p> 1309<h1 id="C_SUPPORT">C++ SUPPORT</h1><p><a href="#TOP" class="toplink">Top</a></p>
1130<div id="C_SUPPORT_CONTENT"> 1310<div id="C_SUPPORT_CONTENT">
1131<p>TBD.</p> 1311<p>Libev comes with some simplistic wrapper classes for C++ that mainly allow
1312you to use some convinience methods to start/stop watchers and also change
1313the callback model to a model using method callbacks on objects.</p>
1314<p>To use it,</p>
1315<pre> #include &lt;ev++.h&gt;
1316
1317</pre>
1318<p>(it is not installed by default). This automatically includes <cite>ev.h</cite>
1319and puts all of its definitions (many of them macros) into the global
1320namespace. All C++ specific things are put into the <code>ev</code> namespace.</p>
1321<p>It should support all the same embedding options as <cite>ev.h</cite>, most notably
1322<code>EV_MULTIPLICITY</code>.</p>
1323<p>Here is a list of things available in the <code>ev</code> namespace:</p>
1324<dl>
1325 <dt><code>ev::READ</code>, <code>ev::WRITE</code> etc.</dt>
1326 <dd>
1327 <p>These are just enum values with the same values as the <code>EV_READ</code> etc.
1328macros from <cite>ev.h</cite>.</p>
1329 </dd>
1330 <dt><code>ev::tstamp</code>, <code>ev::now</code></dt>
1331 <dd>
1332 <p>Aliases to the same types/functions as with the <code>ev_</code> prefix.</p>
1333 </dd>
1334 <dt><code>ev::io</code>, <code>ev::timer</code>, <code>ev::periodic</code>, <code>ev::idle</code>, <code>ev::sig</code> etc.</dt>
1335 <dd>
1336 <p>For each <code>ev_TYPE</code> watcher in <cite>ev.h</cite> there is a corresponding class of
1337the same name in the <code>ev</code> namespace, with the exception of <code>ev_signal</code>
1338which is called <code>ev::sig</code> to avoid clashes with the <code>signal</code> macro
1339defines by many implementations.</p>
1340 <p>All of those classes have these methods:</p>
1341 <p>
1342 <dl>
1343 <dt>ev::TYPE::TYPE (object *, object::method *)</dt>
1344 <dt>ev::TYPE::TYPE (object *, object::method *, struct ev_loop *)</dt>
1345 <dt>ev::TYPE::~TYPE</dt>
1346 <dd>
1347 <p>The constructor takes a pointer to an object and a method pointer to
1348the event handler callback to call in this class. The constructor calls
1349<code>ev_init</code> for you, which means you have to call the <code>set</code> method
1350before starting it. If you do not specify a loop then the constructor
1351automatically associates the default loop with this watcher.</p>
1352 <p>The destructor automatically stops the watcher if it is active.</p>
1353 </dd>
1354 <dt>w-&gt;set (struct ev_loop *)</dt>
1355 <dd>
1356 <p>Associates a different <code>struct ev_loop</code> with this watcher. You can only
1357do this when the watcher is inactive (and not pending either).</p>
1358 </dd>
1359 <dt>w-&gt;set ([args])</dt>
1360 <dd>
1361 <p>Basically the same as <code>ev_TYPE_set</code>, with the same args. Must be
1362called at least once. Unlike the C counterpart, an active watcher gets
1363automatically stopped and restarted.</p>
1364 </dd>
1365 <dt>w-&gt;start ()</dt>
1366 <dd>
1367 <p>Starts the watcher. Note that there is no <code>loop</code> argument as the
1368constructor already takes the loop.</p>
1369 </dd>
1370 <dt>w-&gt;stop ()</dt>
1371 <dd>
1372 <p>Stops the watcher if it is active. Again, no <code>loop</code> argument.</p>
1373 </dd>
1374 <dt>w-&gt;again () <code>ev::timer</code>, <code>ev::periodic</code> only</dt>
1375 <dd>
1376 <p>For <code>ev::timer</code> and <code>ev::periodic</code>, this invokes the corresponding
1377<code>ev_TYPE_again</code> function.</p>
1378 </dd>
1379 <dt>w-&gt;sweep () <code>ev::embed</code> only</dt>
1380 <dd>
1381 <p>Invokes <code>ev_embed_sweep</code>.</p>
1382 </dd>
1383 </dl>
1384 </p>
1385 </dd>
1386</dl>
1387<p>Example: Define a class with an IO and idle watcher, start one of them in
1388the constructor.</p>
1389<pre> class myclass
1390 {
1391 ev_io io; void io_cb (ev::io &amp;w, int revents);
1392 ev_idle idle void idle_cb (ev::idle &amp;w, int revents);
1393
1394 myclass ();
1395 }
1396
1397 myclass::myclass (int fd)
1398 : io (this, &amp;myclass::io_cb),
1399 idle (this, &amp;myclass::idle_cb)
1400 {
1401 io.start (fd, ev::READ);
1402 }
1403
1404</pre>
1132 1405
1133</div> 1406</div>
1134<h1 id="AUTHOR">AUTHOR</h1><p><a href="#TOP" class="toplink">Top</a></p> 1407<h1 id="AUTHOR">AUTHOR</h1><p><a href="#TOP" class="toplink">Top</a></p>
1135<div id="AUTHOR_CONTENT"> 1408<div id="AUTHOR_CONTENT">
1136<p>Marc Lehmann &lt;libev@schmorp.de&gt;.</p> 1409<p>Marc Lehmann &lt;libev@schmorp.de&gt;.</p>

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