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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 09:58:24 2007" /> 9 <meta name="created" content="Mon Nov 12 10:07:10 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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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_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> 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</ul> 37</ul>
38</li> 38</li>
39<li><a href="#OTHER_FUNCTIONS">OTHER FUNCTIONS</a></li> 39<li><a href="#OTHER_FUNCTIONS">OTHER FUNCTIONS</a></li>
40<li><a href="#LIBEVENT_EMULATION">LIBEVENT EMULATION</a></li>
41<li><a href="#C_SUPPORT">C++ SUPPORT</a></li>
40<li><a href="#AUTHOR">AUTHOR</a> 42<li><a href="#AUTHOR">AUTHOR</a>
41</li> 43</li>
42</ul><hr /> 44</ul><hr />
43<!-- INDEX END --> 45<!-- INDEX END -->
44 46
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99to the double type in C.</p> 101to the double type in C.</p>
100 102
101</div> 103</div>
102<h1 id="GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p> 104<h1 id="GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p>
103<div id="GLOBAL_FUNCTIONS_CONTENT"> 105<div id="GLOBAL_FUNCTIONS_CONTENT">
106<p>These functions can be called anytime, even before initialising the
107library in any way.</p>
104<dl> 108<dl>
105 <dt>ev_tstamp ev_time ()</dt> 109 <dt>ev_tstamp ev_time ()</dt>
106 <dd> 110 <dd>
107 <p>Returns the current time as libev would use it.</p> 111 <p>Returns the current time as libev would use it.</p>
108 </dd> 112 </dd>
… …
567 <dd> 571 <dd>
568 <p>In this mode the values for <code>interval</code> and <code>at</code> are both being 572 <p>In this mode the values for <code>interval</code> and <code>at</code> are both being
569ignored. Instead, each time the periodic watcher gets scheduled, the 573ignored. Instead, each time the periodic watcher gets scheduled, the
570reschedule callback will be called with the watcher as first, and the 574reschedule callback will be called with the watcher as first, and the
571current time as second argument.</p> 575current time as second argument.</p>
572 <p>NOTE: <i>This callback MUST NOT stop or destroy the periodic or any other 576 <p>NOTE: <i>This callback MUST NOT stop or destroy any periodic watcher,
573periodic watcher, ever, or make any event loop modifications</i>. If you need 577ever, or make any event loop modifications</i>. If you need to stop it,
574to stop it, return <code>now + 1e30</code> (or so, fudge fudge) and stop it afterwards.</p> 578return <code>now + 1e30</code> (or so, fudge fudge) and stop it afterwards (e.g. by
575 <p>Also, <i>this callback must always return a time that is later than the 579starting a prepare watcher).</p>
576passed <code>now</code> value</i>. Not even <code>now</code> itself will be ok.</p>
577 <p>Its prototype is <code>ev_tstamp (*reschedule_cb)(struct ev_periodic *w, 580 <p>Its prototype is <code>ev_tstamp (*reschedule_cb)(struct ev_periodic *w,
578ev_tstamp now)</code>, e.g.:</p> 581ev_tstamp now)</code>, e.g.:</p>
579<pre> static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now) 582<pre> static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now)
580 { 583 {
581 return now + 60.; 584 return now + 60.;
… …
584</pre> 587</pre>
585 <p>It must return the next time to trigger, based on the passed time value 588 <p>It must return the next time to trigger, based on the passed time value
586(that is, the lowest time value larger than to the second argument). It 589(that is, the lowest time value larger than to the second argument). It
587will usually be called just before the callback will be triggered, but 590will usually be called just before the callback will be triggered, but
588might be called at other times, too.</p> 591might be called at other times, too.</p>
592 <p>NOTE: <i>This callback must always return a time that is later than the
593passed <code>now</code> value</i>. Not even <code>now</code> itself will do, it <i>must</i> be larger.</p>
589 <p>This can be used to create very complex timers, such as a timer that 594 <p>This can be used to create very complex timers, such as a timer that
590triggers on each midnight, local time. To do this, you would calculate the 595triggers on each midnight, local time. To do this, you would calculate the
591next midnight after <code>now</code> and return the timestamp value for this. How you do this 596next midnight after <code>now</code> and return the timestamp value for this. How
592is, again, up to you (but it is not trivial).</p> 597you do this is, again, up to you (but it is not trivial, which is the main
598reason I omitted it as an example).</p>
593 </dd> 599 </dd>
594 </dl> 600 </dl>
595 </p> 601 </p>
596 </dd> 602 </dd>
597 <dt>ev_periodic_again (loop, ev_periodic *)</dt> 603 <dt>ev_periodic_again (loop, ev_periodic *)</dt>
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670 676
671</div> 677</div>
672<h2 id="code_ev_prepare_code_and_code_ev_che"><code>ev_prepare</code> and <code>ev_check</code> - customise your event loop</h2> 678<h2 id="code_ev_prepare_code_and_code_ev_che"><code>ev_prepare</code> and <code>ev_check</code> - customise your event loop</h2>
673<div id="code_ev_prepare_code_and_code_ev_che-2"> 679<div id="code_ev_prepare_code_and_code_ev_che-2">
674<p>Prepare and check watchers are usually (but not always) used in tandem: 680<p>Prepare and check watchers are usually (but not always) used in tandem:
675Prepare watchers get invoked before the process blocks and check watchers 681prepare watchers get invoked before the process blocks and check watchers
676afterwards.</p> 682afterwards.</p>
677<p>Their main purpose is to integrate other event mechanisms into libev. This 683<p>Their main purpose is to integrate other event mechanisms into libev. This
678could be used, for example, to track variable changes, implement your own 684could be used, for example, to track variable changes, implement your own
679watchers, integrate net-snmp or a coroutine library and lots more.</p> 685watchers, integrate net-snmp or a coroutine library and lots more.</p>
680<p>This is done by examining in each prepare call which file descriptors need 686<p>This is done by examining in each prepare call which file descriptors need
681to be watched by the other library, registering <code>ev_io</code> watchers for 687to be watched by the other library, registering <code>ev_io</code> watchers for
682them and starting an <code>ev_timer</code> watcher for any timeouts (many libraries 688them and starting an <code>ev_timer</code> watcher for any timeouts (many libraries
683provide just this functionality). Then, in the check watcher you check for 689provide just this functionality). Then, in the check watcher you check for
684any events that occured (by checking the pending status of all watchers 690any events that occured (by checking the pending status of all watchers
685and stopping them) and call back into the library. The I/O and timer 691and stopping them) and call back into the library. The I/O and timer
686callbacks will never actually be called (but must be valid neverthelles, 692callbacks will never actually be called (but must be valid nevertheless,
687because you never know, you know?).</p> 693because you never know, you know?).</p>
688<p>As another example, the Perl Coro module uses these hooks to integrate 694<p>As another example, the Perl Coro module uses these hooks to integrate
689coroutines into libev programs, by yielding to other active coroutines 695coroutines into libev programs, by yielding to other active coroutines
690during each prepare and only letting the process block if no coroutines 696during each prepare and only letting the process block if no coroutines
691are ready to run (its actually more complicated, it only runs coroutines 697are ready to run (it's actually more complicated: it only runs coroutines
692with priority higher than the event loop and one lower priority once, 698with priority higher than or equal to the event loop and one coroutine
693using idle watchers to keep the event loop from blocking if lower-priority 699of lower priority, but only once, using idle watchers to keep the event
694coroutines exist, thus mapping low-priority coroutines to idle/background 700loop from blocking if lower-priority coroutines are active, thus mapping
695tasks).</p> 701low-priority coroutines to idle/background tasks).</p>
696<dl> 702<dl>
697 <dt>ev_prepare_init (ev_prepare *, callback)</dt> 703 <dt>ev_prepare_init (ev_prepare *, callback)</dt>
698 <dt>ev_check_init (ev_check *, callback)</dt> 704 <dt>ev_check_init (ev_check *, callback)</dt>
699 <dd> 705 <dd>
700 <p>Initialises and configures the prepare or check watcher - they have no 706 <p>Initialises and configures the prepare or check watcher - they have no
… …
721 <p>If <code>timeout</code> is less than 0, then no timeout watcher will be 727 <p>If <code>timeout</code> is less than 0, then no timeout watcher will be
722started. Otherwise an <code>ev_timer</code> watcher with after = <code>timeout</code> (and 728started. Otherwise an <code>ev_timer</code> watcher with after = <code>timeout</code> (and
723repeat = 0) will be started. While <code>0</code> is a valid timeout, it is of 729repeat = 0) will be started. While <code>0</code> is a valid timeout, it is of
724dubious value.</p> 730dubious value.</p>
725 <p>The callback has the type <code>void (*cb)(int revents, void *arg)</code> and gets 731 <p>The callback has the type <code>void (*cb)(int revents, void *arg)</code> and gets
726passed an events set like normal event callbacks (with a combination of 732passed an <code>revents</code> set like normal event callbacks (a combination of
727<code>EV_ERROR</code>, <code>EV_READ</code>, <code>EV_WRITE</code> or <code>EV_TIMEOUT</code>) and the <code>arg</code> 733<code>EV_ERROR</code>, <code>EV_READ</code>, <code>EV_WRITE</code> or <code>EV_TIMEOUT</code>) and the <code>arg</code>
728value passed to <code>ev_once</code>:</p> 734value passed to <code>ev_once</code>:</p>
729<pre> static void stdin_ready (int revents, void *arg) 735<pre> static void stdin_ready (int revents, void *arg)
730 { 736 {
731 if (revents &amp; EV_TIMEOUT) 737 if (revents &amp; EV_TIMEOUT)
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754 <p>Feed an event as if the given signal occured (loop must be the default loop!).</p> 760 <p>Feed an event as if the given signal occured (loop must be the default loop!).</p>
755 </dd> 761 </dd>
756</dl> 762</dl>
757 763
758</div> 764</div>
765<h1 id="LIBEVENT_EMULATION">LIBEVENT EMULATION</h1><p><a href="#TOP" class="toplink">Top</a></p>
766<div id="LIBEVENT_EMULATION_CONTENT">
767<p>TBD.</p>
768
769</div>
770<h1 id="C_SUPPORT">C++ SUPPORT</h1><p><a href="#TOP" class="toplink">Top</a></p>
771<div id="C_SUPPORT_CONTENT">
772<p>TBD.</p>
773
774</div>
759<h1 id="AUTHOR">AUTHOR</h1><p><a href="#TOP" class="toplink">Top</a></p> 775<h1 id="AUTHOR">AUTHOR</h1><p><a href="#TOP" class="toplink">Top</a></p>
760<div id="AUTHOR_CONTENT"> 776<div id="AUTHOR_CONTENT">
761<p>Marc Lehmann &lt;libev@schmorp.de&gt;.</p> 777<p>Marc Lehmann &lt;libev@schmorp.de&gt;.</p>
762 778
763</div> 779</div>

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