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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="Mon Nov 12 09:46:59 2007" /> 9 <meta name="created" content="Mon Nov 12 10:02:16 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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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="#DESCRIPTION">DESCRIPTION</a></li> 19<li><a href="#DESCRIPTION">DESCRIPTION</a></li>
20<li><a href="#FEATURES">FEATURES</a></li> 20<li><a href="#FEATURES">FEATURES</a></li>
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_AND_OTHER_GLOBAL_FUNCTIONS">TIME AND OTHER GLOBAL FUNCTIONS</a></li> 23<li><a href="#GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</a></li>
23<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>
24<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>
25<ul><li><a href="#ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH">ASSOCIATING CUSTOM DATA WITH A WATCHER</a></li> 26<ul><li><a href="#ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH">ASSOCIATING CUSTOM DATA WITH A WATCHER</a></li>
26</ul> 27</ul>
27</li> 28</li>
… …
30<li><a href="#code_ev_timer_code_relative_and_opti"><code>ev_timer</code> - relative and optionally recurring timeouts</a></li> 31<li><a href="#code_ev_timer_code_relative_and_opti"><code>ev_timer</code> - relative and optionally recurring timeouts</a></li>
31<li><a href="#code_ev_periodic_code_to_cron_or_not"><code>ev_periodic</code> - to cron or not to cron</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>
32<li><a href="#code_ev_signal_code_signal_me_when_a"><code>ev_signal</code> - signal me when a signal gets signalled</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>
33<li><a href="#code_ev_child_code_wait_for_pid_stat"><code>ev_child</code> - wait for pid status changes</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>
34<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> 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>
35<li><a href="#code_ev_prepare_code_and_code_ev_che"><code>ev_prepare</code> and <code>ev_check</code> - your hooks into the event loop</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>
36</ul> 37</ul>
37</li> 38</li>
38<li><a href="#OTHER_FUNCTIONS">OTHER FUNCTIONS</a></li> 39<li><a href="#OTHER_FUNCTIONS">OTHER FUNCTIONS</a></li>
39<li><a href="#AUTHOR">AUTHOR</a> 40<li><a href="#AUTHOR">AUTHOR</a>
40</li> 41</li>
… …
87support for multiple event loops, then all functions taking an initial 88support for multiple event loops, then all functions taking an initial
88argument of name <code>loop</code> (which is always of type <code>struct ev_loop *</code>) 89argument of name <code>loop</code> (which is always of type <code>struct ev_loop *</code>)
89will not have this argument.</p> 90will not have this argument.</p>
90 91
91</div> 92</div>
92<h1 id="TIME_AND_OTHER_GLOBAL_FUNCTIONS">TIME AND OTHER GLOBAL FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p> 93<h1 id="TIME_REPRESENTATION">TIME REPRESENTATION</h1><p><a href="#TOP" class="toplink">Top</a></p>
93<div id="TIME_AND_OTHER_GLOBAL_FUNCTIONS_CONT"> 94<div id="TIME_REPRESENTATION_CONTENT">
94<p>Libev represents time as a single floating point number, representing the 95<p>Libev represents time as a single floating point number, representing the
95(fractional) number of seconds since the (POSIX) epoch (somewhere near 96(fractional) number of seconds since the (POSIX) epoch (somewhere near
96the beginning of 1970, details are complicated, don't ask). This type is 97the beginning of 1970, details are complicated, don't ask). This type is
97called <code>ev_tstamp</code>, which is what you should use too. It usually aliases 98called <code>ev_tstamp</code>, which is what you should use too. It usually aliases
98to the double type in C.</p> 99to the double type in C.</p>
100
101</div>
102<h1 id="GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p>
103<div id="GLOBAL_FUNCTIONS_CONTENT">
104<p>These functions can be called anytime, even before initialising the
105library in any way.</p>
99<dl> 106<dl>
100 <dt>ev_tstamp ev_time ()</dt> 107 <dt>ev_tstamp ev_time ()</dt>
101 <dd> 108 <dd>
102 <p>Returns the current time as libev would use it.</p> 109 <p>Returns the current time as libev would use it.</p>
103 </dd> 110 </dd>
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142<div id="FUNCTIONS_CONTROLLING_THE_EVENT_LOOP-2"> 149<div id="FUNCTIONS_CONTROLLING_THE_EVENT_LOOP-2">
143<p>An event loop is described by a <code>struct ev_loop *</code>. The library knows two 150<p>An event loop is described by a <code>struct ev_loop *</code>. The library knows two
144types of such loops, the <i>default</i> loop, which supports signals and child 151types of such loops, the <i>default</i> loop, which supports signals and child
145events, and dynamically created loops which do not.</p> 152events, and dynamically created loops which do not.</p>
146<p>If you use threads, a common model is to run the default event loop 153<p>If you use threads, a common model is to run the default event loop
147in your main thread (or in a separate thrad) and for each thread you 154in your main thread (or in a separate thread) and for each thread you
148create, you also create another event loop. Libev itself does no locking 155create, you also create another event loop. Libev itself does no locking
149whatsoever, so if you mix calls to the same event loop in different 156whatsoever, so if you mix calls to the same event loop in different
150threads, make sure you lock (this is usually a bad idea, though, even if 157threads, make sure you lock (this is usually a bad idea, though, even if
151done correctly, because it's hideous and inefficient).</p> 158done correctly, because it's hideous and inefficient).</p>
152<dl> 159<dl>
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562 <dd> 569 <dd>
563 <p>In this mode the values for <code>interval</code> and <code>at</code> are both being 570 <p>In this mode the values for <code>interval</code> and <code>at</code> are both being
564ignored. Instead, each time the periodic watcher gets scheduled, the 571ignored. Instead, each time the periodic watcher gets scheduled, the
565reschedule callback will be called with the watcher as first, and the 572reschedule callback will be called with the watcher as first, and the
566current time as second argument.</p> 573current time as second argument.</p>
567 <p>NOTE: <i>This callback MUST NOT stop or destroy the periodic or any other 574 <p>NOTE: <i>This callback MUST NOT stop or destroy any periodic watcher,
568periodic watcher, ever, or make any event loop modifications</i>. If you need 575ever, or make any event loop modifications</i>. If you need to stop it,
569to stop it, return <code>now + 1e30</code> (or so, fudge fudge) and stop it afterwards.</p> 576return <code>now + 1e30</code> (or so, fudge fudge) and stop it afterwards (e.g. by
570 <p>Also, <i>this callback must always return a time that is later than the 577starting a prepare watcher).</p>
571passed <code>now</code> value</i>. Not even <code>now</code> itself will be ok.</p>
572 <p>Its prototype is <code>ev_tstamp (*reschedule_cb)(struct ev_periodic *w, 578 <p>Its prototype is <code>ev_tstamp (*reschedule_cb)(struct ev_periodic *w,
573ev_tstamp now)</code>, e.g.:</p> 579ev_tstamp now)</code>, e.g.:</p>
574<pre> static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now) 580<pre> static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now)
575 { 581 {
576 return now + 60.; 582 return now + 60.;
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579</pre> 585</pre>
580 <p>It must return the next time to trigger, based on the passed time value 586 <p>It must return the next time to trigger, based on the passed time value
581(that is, the lowest time value larger than to the second argument). It 587(that is, the lowest time value larger than to the second argument). It
582will usually be called just before the callback will be triggered, but 588will usually be called just before the callback will be triggered, but
583might be called at other times, too.</p> 589might be called at other times, too.</p>
590 <p>NOTE: <i>This callback must always return a time that is later than the
591passed <code>now</code> value</i>. Not even <code>now</code> itself will do, it <i>must</i> be larger.</p>
584 <p>This can be used to create very complex timers, such as a timer that 592 <p>This can be used to create very complex timers, such as a timer that
585triggers on each midnight, local time. To do this, you would calculate the 593triggers on each midnight, local time. To do this, you would calculate the
586next midnight after <code>now</code> and return the timestamp value for this. How you do this 594next midnight after <code>now</code> and return the timestamp value for this. How
587is, again, up to you (but it is not trivial).</p> 595you do this is, again, up to you (but it is not trivial, which is the main
596reason I omitted it as an example).</p>
588 </dd> 597 </dd>
589 </dl> 598 </dl>
590 </p> 599 </p>
591 </dd> 600 </dd>
592 <dt>ev_periodic_again (loop, ev_periodic *)</dt> 601 <dt>ev_periodic_again (loop, ev_periodic *)</dt>
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662believe me.</p> 671believe me.</p>
663 </dd> 672 </dd>
664</dl> 673</dl>
665 674
666</div> 675</div>
667<h2 id="code_ev_prepare_code_and_code_ev_che"><code>ev_prepare</code> and <code>ev_check</code> - your hooks into the event loop</h2> 676<h2 id="code_ev_prepare_code_and_code_ev_che"><code>ev_prepare</code> and <code>ev_check</code> - customise your event loop</h2>
668<div id="code_ev_prepare_code_and_code_ev_che-2"> 677<div id="code_ev_prepare_code_and_code_ev_che-2">
669<p>Prepare and check watchers are usually (but not always) used in tandem: 678<p>Prepare and check watchers are usually (but not always) used in tandem:
670Prepare watchers get invoked before the process blocks and check watchers 679Prepare watchers get invoked before the process blocks and check watchers
671afterwards.</p> 680afterwards.</p>
672<p>Their main purpose is to integrate other event mechanisms into libev. This 681<p>Their main purpose is to integrate other event mechanisms into libev. This

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