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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 09:32:26 2007" /> 9 <meta name="created" content="Mon Nov 12 10:02:16 2007" />
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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>
28<li><a href="#WATCHER_TYPES">WATCHER TYPES</a> 29<li><a href="#WATCHER_TYPES">WATCHER TYPES</a>
29<ul><li><a href="#code_ev_io_code_is_my_file_descripto"><code>ev_io</code> - is my file descriptor readable or writable</a></li> 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>
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 it</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="#prepare_and_check_your_hooks_into_th">prepare and check - 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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322*)</code>), and you can stop watching for events at any time by calling the 329*)</code>), and you can stop watching for events at any time by calling the
323corresponding stop function (<code>ev_&lt;type&gt;_stop (loop, watcher *)</code>.</p> 330corresponding stop function (<code>ev_&lt;type&gt;_stop (loop, watcher *)</code>.</p>
324<p>As long as your watcher is active (has been started but not stopped) you 331<p>As long as your watcher is active (has been started but not stopped) you
325must not touch the values stored in it. Most specifically you must never 332must not touch the values stored in it. Most specifically you must never
326reinitialise it or call its set method.</p> 333reinitialise it or call its set method.</p>
327<p>You cna check whether an event is active by calling the <code>ev_is_active 334<p>You can check whether an event is active by calling the <code>ev_is_active
328(watcher *)</code> macro. To see whether an event is outstanding (but the 335(watcher *)</code> macro. To see whether an event is outstanding (but the
329callback for it has not been called yet) you cna use the <code>ev_is_pending 336callback for it has not been called yet) you can use the <code>ev_is_pending
330(watcher *)</code> macro.</p> 337(watcher *)</code> macro.</p>
331<p>Each and every callback receives the event loop pointer as first, the 338<p>Each and every callback receives the event loop pointer as first, the
332registered watcher structure as second, and a bitset of received events as 339registered watcher structure as second, and a bitset of received events as
333third argument.</p> 340third argument.</p>
334<p>The rceeived events usually include a single bit per event type received 341<p>The received events usually include a single bit per event type received
335(you can receive multiple events at the same time). The possible bit masks 342(you can receive multiple events at the same time). The possible bit masks
336are:</p> 343are:</p>
337<dl> 344<dl>
338 <dt><code>EV_READ</code></dt> 345 <dt><code>EV_READ</code></dt>
339 <dt><code>EV_WRITE</code></dt> 346 <dt><code>EV_WRITE</code></dt>
… …
389 396
390</div> 397</div>
391<h2 id="ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH">ASSOCIATING CUSTOM DATA WITH A WATCHER</h2> 398<h2 id="ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH">ASSOCIATING CUSTOM DATA WITH A WATCHER</h2>
392<div id="ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH-2"> 399<div id="ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH-2">
393<p>Each watcher has, by default, a member <code>void *data</code> that you can change 400<p>Each watcher has, by default, a member <code>void *data</code> that you can change
394and read at any time, libev will completely ignore it. This cna be used 401and read at any time, libev will completely ignore it. This can be used
395to associate arbitrary data with your watcher. If you need more data and 402to associate arbitrary data with your watcher. If you need more data and
396don't want to allocate memory and store a pointer to it in that data 403don't want to allocate memory and store a pointer to it in that data
397member, you can also &quot;subclass&quot; the watcher type and provide your own 404member, you can also &quot;subclass&quot; the watcher type and provide your own
398data:</p> 405data:</p>
399<pre> struct my_io 406<pre> struct my_io
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426<div id="WATCHER_TYPES_CONTENT"> 433<div id="WATCHER_TYPES_CONTENT">
427<p>This section describes each watcher in detail, but will not repeat 434<p>This section describes each watcher in detail, but will not repeat
428information given in the last section.</p> 435information given in the last section.</p>
429 436
430</div> 437</div>
431<h2 id="code_ev_io_code_is_my_file_descripto"><code>ev_io</code> - is my file descriptor readable or writable</h2> 438<h2 id="code_ev_io_code_is_this_file_descrip"><code>ev_io</code> - is this file descriptor readable or writable</h2>
432<div id="code_ev_io_code_is_my_file_descripto-2"> 439<div id="code_ev_io_code_is_this_file_descrip-2">
433<p>I/O watchers check whether a file descriptor is readable or writable 440<p>I/O watchers check whether a file descriptor is readable or writable
434in each iteration of the event loop (This behaviour is called 441in each iteration of the event loop (This behaviour is called
435level-triggering because you keep receiving events as long as the 442level-triggering because you keep receiving events as long as the
436condition persists. Remember you cna stop the watcher if you don't want to 443condition persists. Remember you can stop the watcher if you don't want to
437act on the event and neither want to receive future events).</p> 444act on the event and neither want to receive future events).</p>
438<p>In general you can register as many read and/or write event watchers oer 445<p>In general you can register as many read and/or write event watchers oer
439fd as you want (as long as you don't confuse yourself). Setting all file 446fd as you want (as long as you don't confuse yourself). Setting all file
440descriptors to non-blocking mode is also usually a good idea (but not 447descriptors to non-blocking mode is also usually a good idea (but not
441required if you know what you are doing).</p> 448required if you know what you are doing).</p>
… …
505the timer, and again will automatically restart it if need be.</p> 512the timer, and again will automatically restart it if need be.</p>
506 </dd> 513 </dd>
507</dl> 514</dl>
508 515
509</div> 516</div>
510<h2 id="code_ev_periodic_code_to_cron_or_not"><code>ev_periodic</code> - to cron or not to cron it</h2> 517<h2 id="code_ev_periodic_code_to_cron_or_not"><code>ev_periodic</code> - to cron or not to cron</h2>
511<div id="code_ev_periodic_code_to_cron_or_not-2"> 518<div id="code_ev_periodic_code_to_cron_or_not-2">
512<p>Periodic watchers are also timers of a kind, but they are very versatile 519<p>Periodic watchers are also timers of a kind, but they are very versatile
513(and unfortunately a bit complex).</p> 520(and unfortunately a bit complex).</p>
514<p>Unlike <code>ev_timer</code>'s, they are not based on real time (or relative time) 521<p>Unlike <code>ev_timer</code>'s, they are not based on real time (or relative time)
515but on wallclock time (absolute time). You can tell a periodic watcher 522but on wallclock time (absolute time). You can tell a periodic watcher
… …
550<pre> ev_periodic_set (&amp;periodic, 0., 3600., 0); 557<pre> ev_periodic_set (&amp;periodic, 0., 3600., 0);
551 558
552</pre> 559</pre>
553 <p>This doesn't mean there will always be 3600 seconds in between triggers, 560 <p>This doesn't mean there will always be 3600 seconds in between triggers,
554but only that the the callback will be called when the system time shows a 561but only that the the callback will be called when the system time shows a
555full hour (UTC), or more correct, when the system time is evenly divisible 562full hour (UTC), or more correctly, when the system time is evenly divisible
556by 3600.</p> 563by 3600.</p>
557 <p>Another way to think about it (for the mathematically inclined) is that 564 <p>Another way to think about it (for the mathematically inclined) is that
558<code>ev_periodic</code> will try to run the callback in this mode at the next possible 565<code>ev_periodic</code> will try to run the callback in this mode at the next possible
559time where <code>time = at (mod interval)</code>, regardless of any time jumps.</p> 566time where <code>time = at (mod interval)</code>, regardless of any time jumps.</p>
560 </dd> 567 </dd>
… …
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 modificstions</i>. If you need 575ever, or make any event loop modifications</i>. If you need to stop it,
569to stop it, return 1e30 (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
577starting a prepare watcher).</p>
570 <p>Its prototype is c&lt;ev_tstamp (*reschedule_cb)(struct ev_periodic *w, 578 <p>Its prototype is <code>ev_tstamp (*reschedule_cb)(struct ev_periodic *w,
571ev_tstamp now)&gt;, e.g.:</p> 579ev_tstamp now)</code>, e.g.:</p>
572<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)
573 { 581 {
574 return now + 60.; 582 return now + 60.;
575 } 583 }
576 584
577</pre> 585</pre>
578 <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
579(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
580will usually be called just before the callback will be triggered, but 588will usually be called just before the callback will be triggered, but
581might 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>
582 <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
583triggers 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
584next 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
585is, 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>
586 </dd> 597 </dd>
587 </dl> 598 </dl>
588 </p> 599 </p>
589 </dd> 600 </dd>
590 <dt>ev_periodic_again (loop, ev_periodic *)</dt> 601 <dt>ev_periodic_again (loop, ev_periodic *)</dt>
… …
601<div id="code_ev_signal_code_signal_me_when_a-2"> 612<div id="code_ev_signal_code_signal_me_when_a-2">
602<p>Signal watchers will trigger an event when the process receives a specific 613<p>Signal watchers will trigger an event when the process receives a specific
603signal one or more times. Even though signals are very asynchronous, libev 614signal one or more times. Even though signals are very asynchronous, libev
604will try it's best to deliver signals synchronously, i.e. as part of the 615will try it's best to deliver signals synchronously, i.e. as part of the
605normal event processing, like any other event.</p> 616normal event processing, like any other event.</p>
606<p>You cna configure as many watchers as you like per signal. Only when the 617<p>You can configure as many watchers as you like per signal. Only when the
607first watcher gets started will libev actually register a signal watcher 618first watcher gets started will libev actually register a signal watcher
608with the kernel (thus it coexists with your own signal handlers as long 619with the kernel (thus it coexists with your own signal handlers as long
609as you don't register any with libev). Similarly, when the last signal 620as you don't register any with libev). Similarly, when the last signal
610watcher for a signal is stopped libev will reset the signal handler to 621watcher for a signal is stopped libev will reset the signal handler to
611SIG_DFL (regardless of what it was set to before).</p> 622SIG_DFL (regardless of what it was set to before).</p>
… …
628 <dt>ev_child_set (ev_child *, int pid)</dt> 639 <dt>ev_child_set (ev_child *, int pid)</dt>
629 <dd> 640 <dd>
630 <p>Configures the watcher to wait for status changes of process <code>pid</code> (or 641 <p>Configures the watcher to wait for status changes of process <code>pid</code> (or
631<i>any</i> process if <code>pid</code> is specified as <code>0</code>). The callback can look 642<i>any</i> process if <code>pid</code> is specified as <code>0</code>). The callback can look
632at the <code>rstatus</code> member of the <code>ev_child</code> watcher structure to see 643at the <code>rstatus</code> member of the <code>ev_child</code> watcher structure to see
633the status word (use the macros from <code>sys/wait.h</code>). The <code>rpid</code> member 644the status word (use the macros from <code>sys/wait.h</code> and see your systems
645<code>waitpid</code> documentation). The <code>rpid</code> member contains the pid of the
634contains the pid of the process causing the status change.</p> 646process causing the status change.</p>
635 </dd> 647 </dd>
636</dl> 648</dl>
637 649
638</div> 650</div>
639<h2 id="code_ev_idle_code_when_you_ve_got_no"><code>ev_idle</code> - when you've got nothing better to do</h2> 651<h2 id="code_ev_idle_code_when_you_ve_got_no"><code>ev_idle</code> - when you've got nothing better to do</h2>
640<div id="code_ev_idle_code_when_you_ve_got_no-2"> 652<div id="code_ev_idle_code_when_you_ve_got_no-2">
641<p>Idle watchers trigger events when there are no other I/O or timer (or 653<p>Idle watchers trigger events when there are no other events are pending
642periodic) events pending. That is, as long as your process is busy 654(prepare, check and other idle watchers do not count). That is, as long
643handling sockets or timeouts it will not be called. But when your process 655as your process is busy handling sockets or timeouts (or even signals,
644is idle all idle watchers are being called again and again - until 656imagine) it will not be triggered. But when your process is idle all idle
657watchers are being called again and again, once per event loop iteration -
645stopped, that is, or your process receives more events.</p> 658until stopped, that is, or your process receives more events and becomes
659busy.</p>
646<p>The most noteworthy effect is that as long as any idle watchers are 660<p>The most noteworthy effect is that as long as any idle watchers are
647active, the process will not block when waiting for new events.</p> 661active, the process will not block when waiting for new events.</p>
648<p>Apart from keeping your process non-blocking (which is a useful 662<p>Apart from keeping your process non-blocking (which is a useful
649effect on its own sometimes), idle watchers are a good place to do 663effect on its own sometimes), idle watchers are a good place to do
650&quot;pseudo-background processing&quot;, or delay processing stuff to after the 664&quot;pseudo-background processing&quot;, or delay processing stuff to after the
… …
657believe me.</p> 671believe me.</p>
658 </dd> 672 </dd>
659</dl> 673</dl>
660 674
661</div> 675</div>
662<h2 id="prepare_and_check_your_hooks_into_th">prepare and check - 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>
663<div id="prepare_and_check_your_hooks_into_th-2"> 677<div id="code_ev_prepare_code_and_code_ev_che-2">
664<p>Prepare and check watchers usually (but not always) are used in 678<p>Prepare and check watchers are usually (but not always) used in tandem:
665tandom. Prepare watchers get invoked before the process blocks and check 679Prepare watchers get invoked before the process blocks and check watchers
666watchers afterwards.</p> 680afterwards.</p>
667<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
668could be used, for example, to track variable changes, implement your own 682could be used, for example, to track variable changes, implement your own
669watchers, integrate net-snmp or a coroutine library and lots more.</p> 683watchers, integrate net-snmp or a coroutine library and lots more.</p>
670<p>This is done by examining in each prepare call which file descriptors need 684<p>This is done by examining in each prepare call which file descriptors need
671to be watched by the other library, registering <code>ev_io</code> watchers for them 685to be watched by the other library, registering <code>ev_io</code> watchers for
672and starting an <code>ev_timer</code> watcher for any timeouts (many libraries provide 686them and starting an <code>ev_timer</code> watcher for any timeouts (many libraries
673just this functionality). Then, in the check watcher you check for any 687provide just this functionality). Then, in the check watcher you check for
674events that occured (by making your callbacks set soem flags for example) 688any events that occured (by checking the pending status of all watchers
675and call back into the library.</p> 689and stopping them) and call back into the library. The I/O and timer
690callbacks will never actually be called (but must be valid neverthelles,
691because you never know, you know?).</p>
676<p>As another example, the perl Coro module uses these hooks to integrate 692<p>As another example, the Perl Coro module uses these hooks to integrate
677coroutines into libev programs, by yielding to other active coroutines 693coroutines into libev programs, by yielding to other active coroutines
678during each prepare and only letting the process block if no coroutines 694during each prepare and only letting the process block if no coroutines
679are ready to run.</p> 695are ready to run (its actually more complicated, it only runs coroutines
696with priority higher than the event loop and one lower priority once,
697using idle watchers to keep the event loop from blocking if lower-priority
698coroutines exist, thus mapping low-priority coroutines to idle/background
699tasks).</p>
680<dl> 700<dl>
681 <dt>ev_prepare_init (ev_prepare *, callback)</dt> 701 <dt>ev_prepare_init (ev_prepare *, callback)</dt>
682 <dt>ev_check_init (ev_check *, callback)</dt> 702 <dt>ev_check_init (ev_check *, callback)</dt>
683 <dd> 703 <dd>
684 <p>Initialises and configures the prepare or check watcher - they have no 704 <p>Initialises and configures the prepare or check watcher - they have no
685parameters of any kind. There are <code>ev_prepare_set</code> and <code>ev_check_set</code> 705parameters of any kind. There are <code>ev_prepare_set</code> and <code>ev_check_set</code>
686macros, but using them is utterly, utterly pointless.</p> 706macros, but using them is utterly, utterly and completely pointless.</p>
687 </dd> 707 </dd>
688</dl> 708</dl>
689 709
690</div> 710</div>
691<h1 id="OTHER_FUNCTIONS">OTHER FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p> 711<h1 id="OTHER_FUNCTIONS">OTHER FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p>
692<div id="OTHER_FUNCTIONS_CONTENT"> 712<div id="OTHER_FUNCTIONS_CONTENT">
693<p>There are some other fucntions of possible interest. Described. Here. Now.</p> 713<p>There are some other functions of possible interest. Described. Here. Now.</p>
694<dl> 714<dl>
695 <dt>ev_once (loop, int fd, int events, ev_tstamp timeout, callback)</dt> 715 <dt>ev_once (loop, int fd, int events, ev_tstamp timeout, callback)</dt>
696 <dd> 716 <dd>
697 <p>This function combines a simple timer and an I/O watcher, calls your 717 <p>This function combines a simple timer and an I/O watcher, calls your
698callback on whichever event happens first and automatically stop both 718callback on whichever event happens first and automatically stop both
699watchers. This is useful if you want to wait for a single event on an fd 719watchers. This is useful if you want to wait for a single event on an fd
700or timeout without havign to allocate/configure/start/stop/free one or 720or timeout without havign to allocate/configure/start/stop/free one or
701more watchers yourself.</p> 721more watchers yourself.</p>
702 <p>If <code>fd</code> is less than 0, then no I/O watcher will be started and events is 722 <p>If <code>fd</code> is less than 0, then no I/O watcher will be started and events
703ignored. Otherwise, an <code>ev_io</code> watcher for the given <code>fd</code> and <code>events</code> set 723is being ignored. Otherwise, an <code>ev_io</code> watcher for the given <code>fd</code> and
704will be craeted and started.</p> 724<code>events</code> set will be craeted and started.</p>
705 <p>If <code>timeout</code> is less than 0, then no timeout watcher will be 725 <p>If <code>timeout</code> is less than 0, then no timeout watcher will be
706started. Otherwise an <code>ev_timer</code> watcher with after = <code>timeout</code> (and repeat 726started. Otherwise an <code>ev_timer</code> watcher with after = <code>timeout</code> (and
707= 0) will be started.</p> 727repeat = 0) will be started. While <code>0</code> is a valid timeout, it is of
728dubious value.</p>
708 <p>The callback has the type <code>void (*cb)(int revents, void *arg)</code> and 729 <p>The callback has the type <code>void (*cb)(int revents, void *arg)</code> and gets
709gets passed an events set (normally a combination of <code>EV_ERROR</code>, <code>EV_READ</code>, 730passed an events set like normal event callbacks (with a combination of
710<code>EV_WRITE</code> or <code>EV_TIMEOUT</code>) and the <code>arg</code> value passed to <code>ev_once</code>:</p> 731<code>EV_ERROR</code>, <code>EV_READ</code>, <code>EV_WRITE</code> or <code>EV_TIMEOUT</code>) and the <code>arg</code>
732value passed to <code>ev_once</code>:</p>
711<pre> static void stdin_ready (int revents, void *arg) 733<pre> static void stdin_ready (int revents, void *arg)
712 { 734 {
713 if (revents &amp; EV_TIMEOUT) 735 if (revents &amp; EV_TIMEOUT)
714 /* doh, nothing entered */ 736 /* doh, nothing entered */;
715 else if (revents &amp; EV_READ) 737 else if (revents &amp; EV_READ)
716 /* stdin might have data for us, joy! */ 738 /* stdin might have data for us, joy! */;
717 } 739 }
718 740
719 ev_once (STDIN_FILENO, EV_READm 10., stdin_ready, 0); 741 ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);
720 742
721</pre> 743</pre>
722 </dd> 744 </dd>
723 <dt>ev_feed_event (loop, watcher, int events)</dt> 745 <dt>ev_feed_event (loop, watcher, int events)</dt>
724 <dd> 746 <dd>
725 <p>Feeds the given event set into the event loop, as if the specified event 747 <p>Feeds the given event set into the event loop, as if the specified event
726has happened for the specified watcher (which must be a pointer to an 748had happened for the specified watcher (which must be a pointer to an
727initialised but not necessarily active event watcher).</p> 749initialised but not necessarily started event watcher).</p>
728 </dd> 750 </dd>
729 <dt>ev_feed_fd_event (loop, int fd, int revents)</dt> 751 <dt>ev_feed_fd_event (loop, int fd, int revents)</dt>
730 <dd> 752 <dd>
731 <p>Feed an event on the given fd, as if a file descriptor backend detected it.</p> 753 <p>Feed an event on the given fd, as if a file descriptor backend detected
754the given events it.</p>
732 </dd> 755 </dd>
733 <dt>ev_feed_signal_event (loop, int signum)</dt> 756 <dt>ev_feed_signal_event (loop, int signum)</dt>
734 <dd> 757 <dd>
735 <p>Feed an event as if the given signal occured (loop must be the default loop!).</p> 758 <p>Feed an event as if the given signal occured (loop must be the default loop!).</p>
736 </dd> 759 </dd>

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