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

Comparing libev/ev.html (file contents):
Revision 1.36 by root, Sat Nov 24 06:23:27 2007 UTC vs.
Revision 1.37 by root, Sat Nov 24 07:14:26 2007 UTC

… …
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="Sat Nov 24 05:58:35 2007" /> 9 <meta name="created" content="Sat Nov 24 08:13:46 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 -->
… …
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>
… …
535with a watcher-specific start function (<code>ev_&lt;type&gt;_start (loop, watcher 536with a watcher-specific start function (<code>ev_&lt;type&gt;_start (loop, watcher
536*)</code>), and you can stop watching for events at any time by calling the 537*)</code>), and you can stop watching for events at any time by calling the
537corresponding stop function (<code>ev_&lt;type&gt;_stop (loop, watcher *)</code>.</p> 538corresponding stop function (<code>ev_&lt;type&gt;_stop (loop, watcher *)</code>.</p>
538<p>As long as your watcher is active (has been started but not stopped) you 539<p>As long as your watcher is active (has been started but not stopped) you
539must not touch the values stored in it. Most specifically you must never 540must not touch the values stored in it. Most specifically you must never
540reinitialise it or call its set macro.</p> 541reinitialise it or call its <code>set</code> macro.</p>
541<p>You can check whether an event is active by calling the <code>ev_is_active
542(watcher *)</code> macro. To see whether an event is outstanding (but the
543callback for it has not been called yet) you can use the <code>ev_is_pending
544(watcher *)</code> macro.</p>
545<p>Each and every callback receives the event loop pointer as first, the 542<p>Each and every callback receives the event loop pointer as first, the
546registered watcher structure as second, and a bitset of received events as 543registered watcher structure as second, and a bitset of received events as
547third argument.</p> 544third argument.</p>
548<p>The received events usually include a single bit per event type received 545<p>The received events usually include a single bit per event type received
549(you can receive multiple events at the same time). The possible bit masks 546(you can receive multiple events at the same time). The possible bit masks
… …
598your callbacks is well-written it can just attempt the operation and cope 595your callbacks is well-written it can just attempt the operation and cope
599with the error from read() or write(). This will not work in multithreaded 596with the error from read() or write(). This will not work in multithreaded
600programs, though, so beware.</p> 597programs, though, so beware.</p>
601 </dd> 598 </dd>
602</dl> 599</dl>
600
601</div>
602<h2 id="SUMMARY_OF_GENERIC_WATCHER_FUNCTIONS">SUMMARY OF GENERIC WATCHER FUNCTIONS</h2>
603<div id="SUMMARY_OF_GENERIC_WATCHER_FUNCTIONS-2">
604<p>In the following description, <code>TYPE</code> stands for the watcher type,
605e.g. <code>timer</code> for <code>ev_timer</code> watchers and <code>io</code> for <code>ev_io</code> watchers.</p>
606<dl>
607 <dt><code>ev_init</code> (ev_TYPE *watcher, callback)</dt>
608 <dd>
609 <p>This macro initialises the generic portion of a watcher. The contents
610of the watcher object can be arbitrary (so <code>malloc</code> will do). Only
611the generic parts of the watcher are initialised, you <i>need</i> to call
612the type-specific <code>ev_TYPE_set</code> macro afterwards to initialise the
613type-specific parts. For each type there is also a <code>ev_TYPE_init</code> macro
614which rolls both calls into one.</p>
615 <p>You can reinitialise a watcher at any time as long as it has been stopped
616(or never started) and there are no pending events outstanding.</p>
617 <p>The callbakc is always of type <code>void (*)(ev_loop *loop, ev_TYPE *watcher,
618int revents)</code>.</p>
619 </dd>
620 <dt><code>ev_TYPE_set</code> (ev_TYPE *, [args])</dt>
621 <dd>
622 <p>This macro initialises the type-specific parts of a watcher. You need to
623call <code>ev_init</code> at least once before you call this macro, but you can
624call <code>ev_TYPE_set</code> any number of times. You must not, however, call this
625macro on a watcher that is active (it can be pending, however, which is a
626difference to the <code>ev_init</code> macro).</p>
627 <p>Although some watcher types do not have type-specific arguments
628(e.g. <code>ev_prepare</code>) you still need to call its <code>set</code> macro.</p>
629 </dd>
630 <dt><code>ev_TYPE_init</code> (ev_TYPE *watcher, callback, [args])</dt>
631 <dd>
632 <p>This convinience macro rolls both <code>ev_init</code> and <code>ev_TYPE_set</code> macro
633calls into a single call. This is the most convinient method to initialise
634a watcher. The same limitations apply, of course.</p>
635 </dd>
636 <dt><code>ev_TYPE_start</code> (loop *, ev_TYPE *watcher)</dt>
637 <dd>
638 <p>Starts (activates) the given watcher. Only active watchers will receive
639events. If the watcher is already active nothing will happen.</p>
640 </dd>
641 <dt><code>ev_TYPE_stop</code> (loop *, ev_TYPE *watcher)</dt>
642 <dd>
643 <p>Stops the given watcher again (if active) and clears the pending
644status. It is possible that stopped watchers are pending (for example,
645non-repeating timers are being stopped when they become pending), but
646<code>ev_TYPE_stop</code> ensures that the watcher is neither active nor pending. If
647you want to free or reuse the memory used by the watcher it is therefore a
648good idea to always call its <code>ev_TYPE_stop</code> function.</p>
649 </dd>
650 <dt>bool ev_is_active (ev_TYPE *watcher)</dt>
651 <dd>
652 <p>Returns a true value iff the watcher is active (i.e. it has been started
653and not yet been stopped). As long as a watcher is active you must not modify
654it.</p>
655 </dd>
656 <dt>bool ev_is_pending (ev_TYPE *watcher)</dt>
657 <dd>
658 <p>Returns a true value iff the watcher is pending, (i.e. it has outstanding
659events but its callback has not yet been invoked). As long as a watcher
660is pending (but not active) you must not call an init function on it (but
661<code>ev_TYPE_set</code> is safe) and you must make sure the watcher is available to
662libev (e.g. you cnanot <code>free ()</code> it).</p>
663 </dd>
664 <dt>callback = ev_cb (ev_TYPE *watcher)</dt>
665 <dd>
666 <p>Returns the callback currently set on the watcher.</p>
667 </dd>
668 <dt>ev_cb_set (ev_TYPE *watcher, callback)</dt>
669 <dd>
670 <p>Change the callback. You can change the callback at virtually any time
671(modulo threads).</p>
672 </dd>
673</dl>
674
675
676
677
603 678
604</div> 679</div>
605<h2 id="ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH">ASSOCIATING CUSTOM DATA WITH A WATCHER</h2> 680<h2 id="ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH">ASSOCIATING CUSTOM DATA WITH A WATCHER</h2>
606<div id="ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH-2"> 681<div id="ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH-2">
607<p>Each watcher has, by default, a member <code>void *data</code> that you can change 682<p>Each watcher has, by default, a member <code>void *data</code> that you can change
… …
1066 1141
1067</div> 1142</div>
1068<h2 id="code_ev_embed_code_when_one_backend_"><code>ev_embed</code> - when one backend isn't enough</h2> 1143<h2 id="code_ev_embed_code_when_one_backend_"><code>ev_embed</code> - when one backend isn't enough</h2>
1069<div id="code_ev_embed_code_when_one_backend_-2"> 1144<div id="code_ev_embed_code_when_one_backend_-2">
1070<p>This is a rather advanced watcher type that lets you embed one event loop 1145<p>This is a rather advanced watcher type that lets you embed one event loop
1071into another.</p> 1146into another (currently only <code>ev_io</code> events are supported in the embedded
1147loop, other types of watchers might be handled in a delayed or incorrect
1148fashion and must not be used).</p>
1072<p>There are primarily two reasons you would want that: work around bugs and 1149<p>There are primarily two reasons you would want that: work around bugs and
1073prioritise I/O.</p> 1150prioritise I/O.</p>
1074<p>As an example for a bug workaround, the kqueue backend might only support 1151<p>As an example for a bug workaround, the kqueue backend might only support
1075sockets on some platform, so it is unusable as generic backend, but you 1152sockets on some platform, so it is unusable as generic backend, but you
1076still want to make use of it because you have many sockets and it scales 1153still want to make use of it because you have many sockets and it scales
… …
1081<p>As for prioritising I/O: rarely you have the case where some fds have 1158<p>As for prioritising I/O: rarely you have the case where some fds have
1082to be watched and handled very quickly (with low latency), and even 1159to be watched and handled very quickly (with low latency), and even
1083priorities and idle watchers might have too much overhead. In this case 1160priorities and idle watchers might have too much overhead. In this case
1084you would put all the high priority stuff in one loop and all the rest in 1161you would put all the high priority stuff in one loop and all the rest in
1085a second one, and embed the second one in the first.</p> 1162a second one, and embed the second one in the first.</p>
1163<p>As long as the watcher is active, the callback will be invoked every time
1164there might be events pending in the embedded loop. The callback must then
1165call <code>ev_embed_sweep (mainloop, watcher)</code> to make a single sweep and invoke
1166their callbacks (you could also start an idle watcher to give the embedded
1167loop strictly lower priority for example). You can also set the callback
1168to <code>0</code>, in which case the embed watcher will automatically execute the
1169embedded loop sweep.</p>
1086<p>As long as the watcher is started it will automatically handle events. The 1170<p>As long as the watcher is started it will automatically handle events. The
1087callback will be invoked whenever some events have been handled. You can 1171callback will be invoked whenever some events have been handled. You can
1088set the callback to <code>0</code> to avoid having to specify one if you are not 1172set the callback to <code>0</code> to avoid having to specify one if you are not
1089interested in that.</p> 1173interested in that.</p>
1090<p>Also, there have not currently been made special provisions for forking: 1174<p>Also, there have not currently been made special provisions for forking:
… …
1117 else 1201 else
1118 loop_lo = loop_hi; 1202 loop_lo = loop_hi;
1119 1203
1120</pre> 1204</pre>
1121<dl> 1205<dl>
1122 <dt>ev_embed_init (ev_embed *, callback, struct ev_loop *loop)</dt> 1206 <dt>ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)</dt>
1123 <dt>ev_embed_set (ev_embed *, callback, struct ev_loop *loop)</dt> 1207 <dt>ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)</dt>
1208 <dd>
1209 <p>Configures the watcher to embed the given loop, which must be
1210embeddable. If the callback is <code>0</code>, then <code>ev_embed_sweep</code> will be
1211invoked automatically, otherwise it is the responsibility of the callback
1212to invoke it (it will continue to be called until the sweep has been done,
1213if you do not want thta, you need to temporarily stop the embed watcher).</p>
1124 <dd> 1214 </dd>
1125 <p>Configures the watcher to embed the given loop, which must be embeddable.</p> 1215 <dt>ev_embed_sweep (loop, ev_embed *)</dt>
1216 <dd>
1217 <p>Make a single, non-blocking sweep over the embedded loop. This works
1218similarly to <code>ev_loop (embedded_loop, EVLOOP_NONBLOCK)</code>, but in the most
1219apropriate way for embedded loops.</p>
1126 </dd> 1220 </dd>
1127</dl> 1221</dl>
1128 1222
1129 1223
1130 1224
… …
1163 1257
1164 ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0); 1258 ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);
1165 1259
1166</pre> 1260</pre>
1167 </dd> 1261 </dd>
1168 <dt>ev_feed_event (loop, watcher, int events)</dt> 1262 <dt>ev_feed_event (ev_loop *, watcher *, int revents)</dt>
1169 <dd> 1263 <dd>
1170 <p>Feeds the given event set into the event loop, as if the specified event 1264 <p>Feeds the given event set into the event loop, as if the specified event
1171had happened for the specified watcher (which must be a pointer to an 1265had happened for the specified watcher (which must be a pointer to an
1172initialised but not necessarily started event watcher).</p> 1266initialised but not necessarily started event watcher).</p>
1173 </dd> 1267 </dd>
1174 <dt>ev_feed_fd_event (loop, int fd, int revents)</dt> 1268 <dt>ev_feed_fd_event (ev_loop *, int fd, int revents)</dt>
1175 <dd> 1269 <dd>
1176 <p>Feed an event on the given fd, as if a file descriptor backend detected 1270 <p>Feed an event on the given fd, as if a file descriptor backend detected
1177the given events it.</p> 1271the given events it.</p>
1178 </dd> 1272 </dd>
1179 <dt>ev_feed_signal_event (loop, int signum)</dt> 1273 <dt>ev_feed_signal_event (ev_loop *loop, int signum)</dt>
1180 <dd> 1274 <dd>
1181 <p>Feed an event as if the given signal occured (loop must be the default loop!).</p> 1275 <p>Feed an event as if the given signal occured (<code>loop</code> must be the default
1276loop!).</p>
1182 </dd> 1277 </dd>
1183</dl> 1278</dl>
1184 1279
1185 1280
1186 1281

Diff Legend

– Removed lines
+ Added lines
< Changed lines
> Changed lines