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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="Tue Nov 27 21:14:27 2007" /> 9 <meta name="created" content="Tue Nov 27 21:26:46 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 -->
15<h3 id="TOP">Index</h3> 15<h3 id="TOP">Index</h3>
16 16
17<ul><li><a href="#NAME">NAME</a></li> 17<ul><li><a href="#NAME">NAME</a></li>
18<li><a href="#SYNOPSIS">SYNOPSIS</a></li> 18<li><a href="#SYNOPSIS">SYNOPSIS</a></li>
19<li><a href="#EXAMPLE_PROGRAM">EXAMPLE PROGRAM</a></li>
19<li><a href="#DESCRIPTION">DESCRIPTION</a></li> 20<li><a href="#DESCRIPTION">DESCRIPTION</a></li>
20<li><a href="#FEATURES">FEATURES</a></li> 21<li><a href="#FEATURES">FEATURES</a></li>
21<li><a href="#CONVENTIONS">CONVENTIONS</a></li> 22<li><a href="#CONVENTIONS">CONVENTIONS</a></li>
22<li><a href="#TIME_REPRESENTATION">TIME REPRESENTATION</a></li> 23<li><a href="#TIME_REPRESENTATION">TIME REPRESENTATION</a></li>
23<li><a href="#GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</a></li> 24<li><a href="#GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</a></li>
66<p>libev - a high performance full-featured event loop written in C</p> 67<p>libev - a high performance full-featured event loop written in C</p>
67 68
68</div> 69</div>
69<h1 id="SYNOPSIS">SYNOPSIS</h1><p><a href="#TOP" class="toplink">Top</a></p> 70<h1 id="SYNOPSIS">SYNOPSIS</h1><p><a href="#TOP" class="toplink">Top</a></p>
70<div id="SYNOPSIS_CONTENT"> 71<div id="SYNOPSIS_CONTENT">
71<pre> /* this is the only header you need */
72 #include &lt;ev.h&gt; 72<pre> #include &lt;ev.h&gt;
73 73
74 /* what follows is a fully working example program */ 74</pre>
75
76</div>
77<h1 id="EXAMPLE_PROGRAM">EXAMPLE PROGRAM</h1><p><a href="#TOP" class="toplink">Top</a></p>
78<div id="EXAMPLE_PROGRAM_CONTENT">
79<pre> #include &lt;ev.h&gt;
80
75 ev_io stdin_watcher; 81 ev_io stdin_watcher;
76 ev_timer timeout_watcher; 82 ev_timer timeout_watcher;
77 83
78 /* called when data readable on stdin */ 84 /* called when data readable on stdin */
79 static void 85 static void
127watcher.</p> 133watcher.</p>
128 134
129</div> 135</div>
130<h1 id="FEATURES">FEATURES</h1><p><a href="#TOP" class="toplink">Top</a></p> 136<h1 id="FEATURES">FEATURES</h1><p><a href="#TOP" class="toplink">Top</a></p>
131<div id="FEATURES_CONTENT"> 137<div id="FEATURES_CONTENT">
132<p>Libev supports select, poll, the linux-specific epoll and the bsd-specific 138<p>Libev supports <code>select</code>, <code>poll</code>, the linux-specific <code>epoll</code>, the
133kqueue mechanisms for file descriptor events, relative timers, absolute 139bsd-specific <code>kqueue</code> and the solaris-specific event port mechanisms
134timers with customised rescheduling, signal events, process status change 140for file descriptor events (<code>ev_io</code>), relative timers (<code>ev_timer</code>),
135events (related to SIGCHLD), and event watchers dealing with the event 141absolute timers with customised rescheduling (<code>ev_periodic</code>), synchronous
136loop mechanism itself (idle, prepare and check watchers). It also is quite 142signals (<code>ev_signal</code>), process status change events (<code>ev_child</code>), and
143event watchers dealing with the event loop mechanism itself (<code>ev_idle</code>,
144<code>ev_embed</code>, <code>ev_prepare</code> and <code>ev_check</code> watchers) as well as
145file watchers (<code>ev_stat</code>) and even limited support for fork events
146(<code>ev_fork</code>).</p>
147<p>It also is quite fast (see this
137fast (see this <a href="http://libev.schmorp.de/bench.html">benchmark</a> comparing 148<a href="http://libev.schmorp.de/bench.html">benchmark</a> comparing it to libevent
138it to libevent for example).</p> 149for example).</p>
139 150
140</div> 151</div>
141<h1 id="CONVENTIONS">CONVENTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p> 152<h1 id="CONVENTIONS">CONVENTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p>
142<div id="CONVENTIONS_CONTENT"> 153<div id="CONVENTIONS_CONTENT">
143<p>Libev is very configurable. In this manual the default configuration 154<p>Libev is very configurable. In this manual the default configuration will
144will be described, which supports multiple event loops. For more info 155be described, which supports multiple event loops. For more info about
145about various configuration options please have a look at the file 156various configuration options please have a look at <strong>EMBED</strong> section in
146<cite>README.embed</cite> in the libev distribution. If libev was configured without 157this manual. If libev was configured without support for multiple event
147support for multiple event loops, then all functions taking an initial 158loops, then all functions taking an initial argument of name <code>loop</code>
148argument of name <code>loop</code> (which is always of type <code>struct ev_loop *</code>) 159(which is always of type <code>struct ev_loop *</code>) will not have this argument.</p>
149will not have this argument.</p>
150 160
151</div> 161</div>
152<h1 id="TIME_REPRESENTATION">TIME REPRESENTATION</h1><p><a href="#TOP" class="toplink">Top</a></p> 162<h1 id="TIME_REPRESENTATION">TIME REPRESENTATION</h1><p><a href="#TOP" class="toplink">Top</a></p>
153<div id="TIME_REPRESENTATION_CONTENT"> 163<div id="TIME_REPRESENTATION_CONTENT">
154<p>Libev represents time as a single floating point number, representing the 164<p>Libev represents time as a single floating point number, representing the
180version of the library your program was compiled against.</p> 190version of the library your program was compiled against.</p>
181 <p>Usually, it's a good idea to terminate if the major versions mismatch, 191 <p>Usually, it's a good idea to terminate if the major versions mismatch,
182as this indicates an incompatible change. Minor versions are usually 192as this indicates an incompatible change. Minor versions are usually
183compatible to older versions, so a larger minor version alone is usually 193compatible to older versions, so a larger minor version alone is usually
184not a problem.</p> 194not a problem.</p>
185 <p>Example: make sure we haven't accidentally been linked against the wrong 195 <p>Example: Make sure we haven't accidentally been linked against the wrong
186version:</p> 196version.</p>
187<pre> assert ((&quot;libev version mismatch&quot;, 197<pre> assert ((&quot;libev version mismatch&quot;,
188 ev_version_major () == EV_VERSION_MAJOR 198 ev_version_major () == EV_VERSION_MAJOR
189 &amp;&amp; ev_version_minor () &gt;= EV_VERSION_MINOR)); 199 &amp;&amp; ev_version_minor () &gt;= EV_VERSION_MINOR));
190 200
191</pre> 201</pre>
229allocated, the library might abort or take some potentially destructive 239allocated, the library might abort or take some potentially destructive
230action. The default is your system realloc function.</p> 240action. The default is your system realloc function.</p>
231 <p>You could override this function in high-availability programs to, say, 241 <p>You could override this function in high-availability programs to, say,
232free some memory if it cannot allocate memory, to use a special allocator, 242free some memory if it cannot allocate memory, to use a special allocator,
233or even to sleep a while and retry until some memory is available.</p> 243or even to sleep a while and retry until some memory is available.</p>
234 <p>Example: replace the libev allocator with one that waits a bit and then 244 <p>Example: Replace the libev allocator with one that waits a bit and then
235retries: better than mine).</p> 245retries).</p>
236<pre> static void * 246<pre> static void *
237 persistent_realloc (void *ptr, size_t size) 247 persistent_realloc (void *ptr, size_t size)
238 { 248 {
239 for (;;) 249 for (;;)
240 { 250 {
259indicating the system call or subsystem causing the problem. If this 269indicating the system call or subsystem causing the problem. If this
260callback is set, then libev will expect it to remedy the sitution, no 270callback is set, then libev will expect it to remedy the sitution, no
261matter what, when it returns. That is, libev will generally retry the 271matter what, when it returns. That is, libev will generally retry the
262requested operation, or, if the condition doesn't go away, do bad stuff 272requested operation, or, if the condition doesn't go away, do bad stuff
263(such as abort).</p> 273(such as abort).</p>
264 <p>Example: do the same thing as libev does internally:</p> 274 <p>Example: This is basically the same thing that libev does internally, too.</p>
265<pre> static void 275<pre> static void
266 fatal_error (const char *msg) 276 fatal_error (const char *msg)
267 { 277 {
268 perror (msg); 278 perror (msg);
269 abort (); 279 abort ();
405 <dd> 415 <dd>
406 <p>Similar to <code>ev_default_loop</code>, but always creates a new event loop that is 416 <p>Similar to <code>ev_default_loop</code>, but always creates a new event loop that is
407always distinct from the default loop. Unlike the default loop, it cannot 417always distinct from the default loop. Unlike the default loop, it cannot
408handle signal and child watchers, and attempts to do so will be greeted by 418handle signal and child watchers, and attempts to do so will be greeted by
409undefined behaviour (or a failed assertion if assertions are enabled).</p> 419undefined behaviour (or a failed assertion if assertions are enabled).</p>
410 <p>Example: try to create a event loop that uses epoll and nothing else.</p> 420 <p>Example: Try to create a event loop that uses epoll and nothing else.</p>
411<pre> struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); 421<pre> struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);
412 if (!epoller) 422 if (!epoller)
413 fatal (&quot;no epoll found here, maybe it hides under your chair&quot;); 423 fatal (&quot;no epoll found here, maybe it hides under your chair&quot;);
414 424
415</pre> 425</pre>
508 be handled here by queueing them when their watcher gets executed. 518 be handled here by queueing them when their watcher gets executed.
509 - If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK 519 - If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK
510 were used, return, otherwise continue with step *. 520 were used, return, otherwise continue with step *.
511 521
512</pre> 522</pre>
513 <p>Example: queue some jobs and then loop until no events are outsanding 523 <p>Example: Queue some jobs and then loop until no events are outsanding
514anymore.</p> 524anymore.</p>
515<pre> ... queue jobs here, make sure they register event watchers as long 525<pre> ... queue jobs here, make sure they register event watchers as long
516 ... as they still have work to do (even an idle watcher will do..) 526 ... as they still have work to do (even an idle watcher will do..)
517 ev_loop (my_loop, 0); 527 ev_loop (my_loop, 0);
518 ... jobs done. yeah! 528 ... jobs done. yeah!
537example, libev itself uses this for its internal signal pipe: It is not 547example, libev itself uses this for its internal signal pipe: It is not
538visible to the libev user and should not keep <code>ev_loop</code> from exiting if 548visible to the libev user and should not keep <code>ev_loop</code> from exiting if
539no event watchers registered by it are active. It is also an excellent 549no event watchers registered by it are active. It is also an excellent
540way to do this for generic recurring timers or from within third-party 550way to do this for generic recurring timers or from within third-party
541libraries. Just remember to <i>unref after start</i> and <i>ref before stop</i>.</p> 551libraries. Just remember to <i>unref after start</i> and <i>ref before stop</i>.</p>
542 <p>Example: create a signal watcher, but keep it from keeping <code>ev_loop</code> 552 <p>Example: Create a signal watcher, but keep it from keeping <code>ev_loop</code>
543running when nothing else is active.</p> 553running when nothing else is active.</p>
544<pre> struct dv_signal exitsig; 554<pre> struct ev_signal exitsig;
545 ev_signal_init (&amp;exitsig, sig_cb, SIGINT); 555 ev_signal_init (&amp;exitsig, sig_cb, SIGINT);
546 ev_signal_start (myloop, &amp;exitsig); 556 ev_signal_start (loop, &amp;exitsig);
547 evf_unref (myloop); 557 evf_unref (loop);
548 558
549</pre> 559</pre>
550 <p>Example: for some weird reason, unregister the above signal handler again.</p> 560 <p>Example: For some weird reason, unregister the above signal handler again.</p>
551<pre> ev_ref (myloop); 561<pre> ev_ref (loop);
552 ev_signal_stop (myloop, &amp;exitsig); 562 ev_signal_stop (loop, &amp;exitsig);
553 563
554</pre> 564</pre>
555 </dd> 565 </dd>
556</dl> 566</dl>
557 567
851 <dt>int events [read-only]</dt> 861 <dt>int events [read-only]</dt>
852 <dd> 862 <dd>
853 <p>The events being watched.</p> 863 <p>The events being watched.</p>
854 </dd> 864 </dd>
855</dl> 865</dl>
856<p>Example: call <code>stdin_readable_cb</code> when STDIN_FILENO has become, well 866<p>Example: Call <code>stdin_readable_cb</code> when STDIN_FILENO has become, well
857readable, but only once. Since it is likely line-buffered, you could 867readable, but only once. Since it is likely line-buffered, you could
858attempt to read a whole line in the callback:</p> 868attempt to read a whole line in the callback.</p>
859<pre> static void 869<pre> static void
860 stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents) 870 stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents)
861 { 871 {
862 ev_io_stop (loop, w); 872 ev_io_stop (loop, w);
863 .. read from stdin here (or from w-&gt;fd) and haqndle any I/O errors 873 .. read from stdin here (or from w-&gt;fd) and haqndle any I/O errors
946 <p>The current <code>repeat</code> value. Will be used each time the watcher times out 956 <p>The current <code>repeat</code> value. Will be used each time the watcher times out
947or <code>ev_timer_again</code> is called and determines the next timeout (if any), 957or <code>ev_timer_again</code> is called and determines the next timeout (if any),
948which is also when any modifications are taken into account.</p> 958which is also when any modifications are taken into account.</p>
949 </dd> 959 </dd>
950</dl> 960</dl>
951<p>Example: create a timer that fires after 60 seconds.</p> 961<p>Example: Create a timer that fires after 60 seconds.</p>
952<pre> static void 962<pre> static void
953 one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) 963 one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents)
954 { 964 {
955 .. one minute over, w is actually stopped right here 965 .. one minute over, w is actually stopped right here
956 } 966 }
958 struct ev_timer mytimer; 968 struct ev_timer mytimer;
959 ev_timer_init (&amp;mytimer, one_minute_cb, 60., 0.); 969 ev_timer_init (&amp;mytimer, one_minute_cb, 60., 0.);
960 ev_timer_start (loop, &amp;mytimer); 970 ev_timer_start (loop, &amp;mytimer);
961 971
962</pre> 972</pre>
963<p>Example: create a timeout timer that times out after 10 seconds of 973<p>Example: Create a timeout timer that times out after 10 seconds of
964inactivity.</p> 974inactivity.</p>
965<pre> static void 975<pre> static void
966 timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents) 976 timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents)
967 { 977 {
968 .. ten seconds without any activity 978 .. ten seconds without any activity
1084 <p>The current reschedule callback, or <code>0</code>, if this functionality is 1094 <p>The current reschedule callback, or <code>0</code>, if this functionality is
1085switched off. Can be changed any time, but changes only take effect when 1095switched off. Can be changed any time, but changes only take effect when
1086the periodic timer fires or <code>ev_periodic_again</code> is being called.</p> 1096the periodic timer fires or <code>ev_periodic_again</code> is being called.</p>
1087 </dd> 1097 </dd>
1088</dl> 1098</dl>
1089<p>Example: call a callback every hour, or, more precisely, whenever the 1099<p>Example: Call a callback every hour, or, more precisely, whenever the
1090system clock is divisible by 3600. The callback invocation times have 1100system clock is divisible by 3600. The callback invocation times have
1091potentially a lot of jittering, but good long-term stability.</p> 1101potentially a lot of jittering, but good long-term stability.</p>
1092<pre> static void 1102<pre> static void
1093 clock_cb (struct ev_loop *loop, struct ev_io *w, int revents) 1103 clock_cb (struct ev_loop *loop, struct ev_io *w, int revents)
1094 { 1104 {
1098 struct ev_periodic hourly_tick; 1108 struct ev_periodic hourly_tick;
1099 ev_periodic_init (&amp;hourly_tick, clock_cb, 0., 3600., 0); 1109 ev_periodic_init (&amp;hourly_tick, clock_cb, 0., 3600., 0);
1100 ev_periodic_start (loop, &amp;hourly_tick); 1110 ev_periodic_start (loop, &amp;hourly_tick);
1101 1111
1102</pre> 1112</pre>
1103<p>Example: the same as above, but use a reschedule callback to do it:</p> 1113<p>Example: The same as above, but use a reschedule callback to do it:</p>
1104<pre> #include &lt;math.h&gt; 1114<pre> #include &lt;math.h&gt;
1105 1115
1106 static ev_tstamp 1116 static ev_tstamp
1107 my_scheduler_cb (struct ev_periodic *w, ev_tstamp now) 1117 my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)
1108 { 1118 {
1110 } 1120 }
1111 1121
1112 ev_periodic_init (&amp;hourly_tick, clock_cb, 0., 0., my_scheduler_cb); 1122 ev_periodic_init (&amp;hourly_tick, clock_cb, 0., 0., my_scheduler_cb);
1113 1123
1114</pre> 1124</pre>
1115<p>Example: call a callback every hour, starting now:</p> 1125<p>Example: Call a callback every hour, starting now:</p>
1116<pre> struct ev_periodic hourly_tick; 1126<pre> struct ev_periodic hourly_tick;
1117 ev_periodic_init (&amp;hourly_tick, clock_cb, 1127 ev_periodic_init (&amp;hourly_tick, clock_cb,
1118 fmod (ev_now (loop), 3600.), 3600., 0); 1128 fmod (ev_now (loop), 3600.), 3600., 0);
1119 ev_periodic_start (loop, &amp;hourly_tick); 1129 ev_periodic_start (loop, &amp;hourly_tick);
1120 1130
1181 <dd> 1191 <dd>
1182 <p>The process exit/trace status caused by <code>rpid</code> (see your systems 1192 <p>The process exit/trace status caused by <code>rpid</code> (see your systems
1183<code>waitpid</code> and <code>sys/wait.h</code> documentation for details).</p> 1193<code>waitpid</code> and <code>sys/wait.h</code> documentation for details).</p>
1184 </dd> 1194 </dd>
1185</dl> 1195</dl>
1186<p>Example: try to exit cleanly on SIGINT and SIGTERM.</p> 1196<p>Example: Try to exit cleanly on SIGINT and SIGTERM.</p>
1187<pre> static void 1197<pre> static void
1188 sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) 1198 sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents)
1189 { 1199 {
1190 ev_unloop (loop, EVUNLOOP_ALL); 1200 ev_unloop (loop, EVUNLOOP_ALL);
1191 } 1201 }
1314 <p>Initialises and configures the idle watcher - it has no parameters of any 1324 <p>Initialises and configures the idle watcher - it has no parameters of any
1315kind. There is a <code>ev_idle_set</code> macro, but using it is utterly pointless, 1325kind. There is a <code>ev_idle_set</code> macro, but using it is utterly pointless,
1316believe me.</p> 1326believe me.</p>
1317 </dd> 1327 </dd>
1318</dl> 1328</dl>
1319<p>Example: dynamically allocate an <code>ev_idle</code>, start it, and in the 1329<p>Example: Dynamically allocate an <code>ev_idle</code> watcher, start it, and in the
1320callback, free it. Alos, use no error checking, as usual.</p> 1330callback, free it. Also, use no error checking, as usual.</p>
1321<pre> static void 1331<pre> static void
1322 idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents) 1332 idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents)
1323 { 1333 {
1324 free (w); 1334 free (w);
1325 // now do something you wanted to do when the program has 1335 // now do something you wanted to do when the program has

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