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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 20:23:27 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>
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71<pre> #include &lt;ev.h&gt; 72<pre> #include &lt;ev.h&gt;
72 73
73</pre> 74</pre>
74 75
75</div> 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
81 ev_io stdin_watcher;
82 ev_timer timeout_watcher;
83
84 /* called when data readable on stdin */
85 static void
86 stdin_cb (EV_P_ struct ev_io *w, int revents)
87 {
88 /* puts (&quot;stdin ready&quot;); */
89 ev_io_stop (EV_A_ w); /* just a syntax example */
90 ev_unloop (EV_A_ EVUNLOOP_ALL); /* leave all loop calls */
91 }
92
93 static void
94 timeout_cb (EV_P_ struct ev_timer *w, int revents)
95 {
96 /* puts (&quot;timeout&quot;); */
97 ev_unloop (EV_A_ EVUNLOOP_ONE); /* leave one loop call */
98 }
99
100 int
101 main (void)
102 {
103 struct ev_loop *loop = ev_default_loop (0);
104
105 /* initialise an io watcher, then start it */
106 ev_io_init (&amp;stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ);
107 ev_io_start (loop, &amp;stdin_watcher);
108
109 /* simple non-repeating 5.5 second timeout */
110 ev_timer_init (&amp;timeout_watcher, timeout_cb, 5.5, 0.);
111 ev_timer_start (loop, &amp;timeout_watcher);
112
113 /* loop till timeout or data ready */
114 ev_loop (loop, 0);
115
116 return 0;
117 }
118
119</pre>
120
121</div>
76<h1 id="DESCRIPTION">DESCRIPTION</h1><p><a href="#TOP" class="toplink">Top</a></p> 122<h1 id="DESCRIPTION">DESCRIPTION</h1><p><a href="#TOP" class="toplink">Top</a></p>
77<div id="DESCRIPTION_CONTENT"> 123<div id="DESCRIPTION_CONTENT">
78<p>Libev is an event loop: you register interest in certain events (such as a 124<p>Libev is an event loop: you register interest in certain events (such as a
79file descriptor being readable or a timeout occuring), and it will manage 125file descriptor being readable or a timeout occuring), and it will manage
80these event sources and provide your program with events.</p> 126these event sources and provide your program with events.</p>
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87watcher.</p> 133watcher.</p>
88 134
89</div> 135</div>
90<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>
91<div id="FEATURES_CONTENT"> 137<div id="FEATURES_CONTENT">
92<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
93kqueue mechanisms for file descriptor events, relative timers, absolute 139bsd-specific <code>kqueue</code> and the solaris-specific event port mechanisms
94timers with customised rescheduling, signal events, process status change 140for file descriptor events (<code>ev_io</code>), relative timers (<code>ev_timer</code>),
95events (related to SIGCHLD), and event watchers dealing with the event 141absolute timers with customised rescheduling (<code>ev_periodic</code>), synchronous
96loop 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
97fast (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
98it to libevent for example).</p> 149for example).</p>
99 150
100</div> 151</div>
101<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>
102<div id="CONVENTIONS_CONTENT"> 153<div id="CONVENTIONS_CONTENT">
103<p>Libev is very configurable. In this manual the default configuration 154<p>Libev is very configurable. In this manual the default configuration will
104will be described, which supports multiple event loops. For more info 155be described, which supports multiple event loops. For more info about
105about various configuration options please have a look at the file 156various configuration options please have a look at <strong>EMBED</strong> section in
106<cite>README.embed</cite> in the libev distribution. If libev was configured without 157this manual. If libev was configured without support for multiple event
107support for multiple event loops, then all functions taking an initial 158loops, then all functions taking an initial argument of name <code>loop</code>
108argument 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>
109will not have this argument.</p>
110 160
111</div> 161</div>
112<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>
113<div id="TIME_REPRESENTATION_CONTENT"> 163<div id="TIME_REPRESENTATION_CONTENT">
114<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
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140version of the library your program was compiled against.</p> 190version of the library your program was compiled against.</p>
141 <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,
142as this indicates an incompatible change. Minor versions are usually 192as this indicates an incompatible change. Minor versions are usually
143compatible to older versions, so a larger minor version alone is usually 193compatible to older versions, so a larger minor version alone is usually
144not a problem.</p> 194not a problem.</p>
145 <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
146version:</p> 196version.</p>
147<pre> assert ((&quot;libev version mismatch&quot;, 197<pre> assert ((&quot;libev version mismatch&quot;,
148 ev_version_major () == EV_VERSION_MAJOR 198 ev_version_major () == EV_VERSION_MAJOR
149 &amp;&amp; ev_version_minor () &gt;= EV_VERSION_MINOR)); 199 &amp;&amp; ev_version_minor () &gt;= EV_VERSION_MINOR));
150 200
151</pre> 201</pre>
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179might be supported on the current system, you would need to look at 229might be supported on the current system, you would need to look at
180<code>ev_embeddable_backends () &amp; ev_supported_backends ()</code>, likewise for 230<code>ev_embeddable_backends () &amp; ev_supported_backends ()</code>, likewise for
181recommended ones.</p> 231recommended ones.</p>
182 <p>See the description of <code>ev_embed</code> watchers for more info.</p> 232 <p>See the description of <code>ev_embed</code> watchers for more info.</p>
183 </dd> 233 </dd>
184 <dt>ev_set_allocator (void *(*cb)(void *ptr, long size))</dt> 234 <dt>ev_set_allocator (void *(*cb)(void *ptr, size_t size))</dt>
185 <dd> 235 <dd>
186 <p>Sets the allocation function to use (the prototype is similar to the 236 <p>Sets the allocation function to use (the prototype and semantics are
187realloc C function, the semantics are identical). It is used to allocate 237identical to the realloc C function). It is used to allocate and free
188and free memory (no surprises here). If it returns zero when memory 238memory (no surprises here). If it returns zero when memory needs to be
189needs to be allocated, the library might abort or take some potentially 239allocated, the library might abort or take some potentially destructive
190destructive action. The default is your system realloc function.</p> 240action. The default is your system realloc function.</p>
191 <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,
192free 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,
193or 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>
194 <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
195retries: better than mine).</p> 245retries).</p>
196<pre> static void * 246<pre> static void *
197 persistent_realloc (void *ptr, long size) 247 persistent_realloc (void *ptr, size_t size)
198 { 248 {
199 for (;;) 249 for (;;)
200 { 250 {
201 void *newptr = realloc (ptr, size); 251 void *newptr = realloc (ptr, size);
202 252
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219indicating the system call or subsystem causing the problem. If this 269indicating the system call or subsystem causing the problem. If this
220callback 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
221matter what, when it returns. That is, libev will generally retry the 271matter what, when it returns. That is, libev will generally retry the
222requested 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
223(such as abort).</p> 273(such as abort).</p>
224 <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>
225<pre> static void 275<pre> static void
226 fatal_error (const char *msg) 276 fatal_error (const char *msg)
227 { 277 {
228 perror (msg); 278 perror (msg);
229 abort (); 279 abort ();
… …
365 <dd> 415 <dd>
366 <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
367always distinct from the default loop. Unlike the default loop, it cannot 417always distinct from the default loop. Unlike the default loop, it cannot
368handle 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
369undefined behaviour (or a failed assertion if assertions are enabled).</p> 419undefined behaviour (or a failed assertion if assertions are enabled).</p>
370 <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>
371<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);
372 if (!epoller) 422 if (!epoller)
373 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;);
374 424
375</pre> 425</pre>
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468 be handled here by queueing them when their watcher gets executed. 518 be handled here by queueing them when their watcher gets executed.
469 - 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
470 were used, return, otherwise continue with step *. 520 were used, return, otherwise continue with step *.
471 521
472</pre> 522</pre>
473 <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
474anymore.</p> 524anymore.</p>
475<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
476 ... 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..)
477 ev_loop (my_loop, 0); 527 ev_loop (my_loop, 0);
478 ... jobs done. yeah! 528 ... jobs done. yeah!
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497example, 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
498visible 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
499no 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
500way 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
501libraries. 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>
502 <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>
503running when nothing else is active.</p> 553running when nothing else is active.</p>
504<pre> struct dv_signal exitsig; 554<pre> struct ev_signal exitsig;
505 ev_signal_init (&amp;exitsig, sig_cb, SIGINT); 555 ev_signal_init (&amp;exitsig, sig_cb, SIGINT);
506 ev_signal_start (myloop, &amp;exitsig); 556 ev_signal_start (loop, &amp;exitsig);
507 evf_unref (myloop); 557 evf_unref (loop);
508 558
509</pre> 559</pre>
510 <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>
511<pre> ev_ref (myloop); 561<pre> ev_ref (loop);
512 ev_signal_stop (myloop, &amp;exitsig); 562 ev_signal_stop (loop, &amp;exitsig);
513 563
514</pre> 564</pre>
515 </dd> 565 </dd>
516</dl> 566</dl>
517 567
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811 <dt>int events [read-only]</dt> 861 <dt>int events [read-only]</dt>
812 <dd> 862 <dd>
813 <p>The events being watched.</p> 863 <p>The events being watched.</p>
814 </dd> 864 </dd>
815</dl> 865</dl>
816<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
817readable, but only once. Since it is likely line-buffered, you could 867readable, but only once. Since it is likely line-buffered, you could
818attempt to read a whole line in the callback:</p> 868attempt to read a whole line in the callback.</p>
819<pre> static void 869<pre> static void
820 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)
821 { 871 {
822 ev_io_stop (loop, w); 872 ev_io_stop (loop, w);
823 .. 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
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906 <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
907or <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),
908which is also when any modifications are taken into account.</p> 958which is also when any modifications are taken into account.</p>
909 </dd> 959 </dd>
910</dl> 960</dl>
911<p>Example: create a timer that fires after 60 seconds.</p> 961<p>Example: Create a timer that fires after 60 seconds.</p>
912<pre> static void 962<pre> static void
913 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)
914 { 964 {
915 .. one minute over, w is actually stopped right here 965 .. one minute over, w is actually stopped right here
916 } 966 }
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918 struct ev_timer mytimer; 968 struct ev_timer mytimer;
919 ev_timer_init (&amp;mytimer, one_minute_cb, 60., 0.); 969 ev_timer_init (&amp;mytimer, one_minute_cb, 60., 0.);
920 ev_timer_start (loop, &amp;mytimer); 970 ev_timer_start (loop, &amp;mytimer);
921 971
922</pre> 972</pre>
923<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
924inactivity.</p> 974inactivity.</p>
925<pre> static void 975<pre> static void
926 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)
927 { 977 {
928 .. ten seconds without any activity 978 .. ten seconds without any activity
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1044 <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
1045switched 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
1046the 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>
1047 </dd> 1097 </dd>
1048</dl> 1098</dl>
1049<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
1050system clock is divisible by 3600. The callback invocation times have 1100system clock is divisible by 3600. The callback invocation times have
1051potentially a lot of jittering, but good long-term stability.</p> 1101potentially a lot of jittering, but good long-term stability.</p>
1052<pre> static void 1102<pre> static void
1053 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)
1054 { 1104 {
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1058 struct ev_periodic hourly_tick; 1108 struct ev_periodic hourly_tick;
1059 ev_periodic_init (&amp;hourly_tick, clock_cb, 0., 3600., 0); 1109 ev_periodic_init (&amp;hourly_tick, clock_cb, 0., 3600., 0);
1060 ev_periodic_start (loop, &amp;hourly_tick); 1110 ev_periodic_start (loop, &amp;hourly_tick);
1061 1111
1062</pre> 1112</pre>
1063<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>
1064<pre> #include &lt;math.h&gt; 1114<pre> #include &lt;math.h&gt;
1065 1115
1066 static ev_tstamp 1116 static ev_tstamp
1067 my_scheduler_cb (struct ev_periodic *w, ev_tstamp now) 1117 my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)
1068 { 1118 {
… …
1070 } 1120 }
1071 1121
1072 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);
1073 1123
1074</pre> 1124</pre>
1075<p>Example: call a callback every hour, starting now:</p> 1125<p>Example: Call a callback every hour, starting now:</p>
1076<pre> struct ev_periodic hourly_tick; 1126<pre> struct ev_periodic hourly_tick;
1077 ev_periodic_init (&amp;hourly_tick, clock_cb, 1127 ev_periodic_init (&amp;hourly_tick, clock_cb,
1078 fmod (ev_now (loop), 3600.), 3600., 0); 1128 fmod (ev_now (loop), 3600.), 3600., 0);
1079 ev_periodic_start (loop, &amp;hourly_tick); 1129 ev_periodic_start (loop, &amp;hourly_tick);
1080 1130
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1141 <dd> 1191 <dd>
1142 <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
1143<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>
1144 </dd> 1194 </dd>
1145</dl> 1195</dl>
1146<p>Example: try to exit cleanly on SIGINT and SIGTERM.</p> 1196<p>Example: Try to exit cleanly on SIGINT and SIGTERM.</p>
1147<pre> static void 1197<pre> static void
1148 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)
1149 { 1199 {
1150 ev_unloop (loop, EVUNLOOP_ALL); 1200 ev_unloop (loop, EVUNLOOP_ALL);
1151 } 1201 }
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1274 <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
1275kind. 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,
1276believe me.</p> 1326believe me.</p>
1277 </dd> 1327 </dd>
1278</dl> 1328</dl>
1279<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
1280callback, free it. Alos, use no error checking, as usual.</p> 1330callback, free it. Also, use no error checking, as usual.</p>
1281<pre> static void 1331<pre> static void
1282 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)
1283 { 1333 {
1284 free (w); 1334 free (w);
1285 // 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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