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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="Sun Dec 9 20:47:27 2007" /> 9 <meta name="created" content="Wed Dec 12 18:55:28 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 -->
… …
27<ul><li><a href="#GENERIC_WATCHER_FUNCTIONS">GENERIC WATCHER FUNCTIONS</a></li> 27<ul><li><a href="#GENERIC_WATCHER_FUNCTIONS">GENERIC WATCHER FUNCTIONS</a></li>
28<li><a href="#ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH">ASSOCIATING CUSTOM DATA WITH A WATCHER</a></li> 28<li><a href="#ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH">ASSOCIATING CUSTOM DATA WITH A WATCHER</a></li>
29</ul> 29</ul>
30</li> 30</li>
31<li><a href="#WATCHER_TYPES">WATCHER TYPES</a> 31<li><a href="#WATCHER_TYPES">WATCHER TYPES</a>
32<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> 32<ul><li><a href="#code_ev_io_code_is_this_file_descrip"><code>ev_io</code> - is this file descriptor readable or writable?</a>
33<ul><li><a href="#The_special_problem_of_disappearing_">The special problem of disappearing file descriptors</a></li>
34<li><a href="#Watcher_Specific_Functions">Watcher-Specific Functions</a></li>
35</ul>
36</li>
33<li><a href="#code_ev_timer_code_relative_and_opti"><code>ev_timer</code> - relative and optionally repeating timeouts</a></li> 37<li><a href="#code_ev_timer_code_relative_and_opti"><code>ev_timer</code> - relative and optionally repeating timeouts</a>
38<ul><li><a href="#Watcher_Specific_Functions_and_Data_">Watcher-Specific Functions and Data Members</a></li>
39</ul>
40</li>
34<li><a href="#code_ev_periodic_code_to_cron_or_not"><code>ev_periodic</code> - to cron or not to cron?</a></li> 41<li><a href="#code_ev_periodic_code_to_cron_or_not"><code>ev_periodic</code> - to cron or not to cron?</a>
42<ul><li><a href="#Watcher_Specific_Functions_and_Data_-3">Watcher-Specific Functions and Data Members</a></li>
43</ul>
44</li>
35<li><a href="#code_ev_signal_code_signal_me_when_a"><code>ev_signal</code> - signal me when a signal gets signalled!</a></li> 45<li><a href="#code_ev_signal_code_signal_me_when_a"><code>ev_signal</code> - signal me when a signal gets signalled!</a>
46<ul><li><a href="#Watcher_Specific_Functions_and_Data_-4">Watcher-Specific Functions and Data Members</a></li>
47</ul>
48</li>
36<li><a href="#code_ev_child_code_watch_out_for_pro"><code>ev_child</code> - watch out for process status changes</a></li> 49<li><a href="#code_ev_child_code_watch_out_for_pro"><code>ev_child</code> - watch out for process status changes</a>
50<ul><li><a href="#Watcher_Specific_Functions_and_Data_-5">Watcher-Specific Functions and Data Members</a></li>
51</ul>
52</li>
37<li><a href="#code_ev_stat_code_did_the_file_attri"><code>ev_stat</code> - did the file attributes just change?</a></li> 53<li><a href="#code_ev_stat_code_did_the_file_attri"><code>ev_stat</code> - did the file attributes just change?</a>
54<ul><li><a href="#Watcher_Specific_Functions_and_Data_-6">Watcher-Specific Functions and Data Members</a></li>
55</ul>
56</li>
38<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> 57<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>
58<ul><li><a href="#Watcher_Specific_Functions_and_Data_-7">Watcher-Specific Functions and Data Members</a></li>
59</ul>
60</li>
39<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> 61<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>
62<ul><li><a href="#Watcher_Specific_Functions_and_Data_-8">Watcher-Specific Functions and Data Members</a></li>
63</ul>
64</li>
40<li><a href="#code_ev_embed_code_when_one_backend_"><code>ev_embed</code> - when one backend isn't enough...</a></li> 65<li><a href="#code_ev_embed_code_when_one_backend_"><code>ev_embed</code> - when one backend isn't enough...</a>
66<ul><li><a href="#Watcher_Specific_Functions_and_Data_-9">Watcher-Specific Functions and Data Members</a></li>
67</ul>
68</li>
41<li><a href="#code_ev_fork_code_the_audacity_to_re"><code>ev_fork</code> - the audacity to resume the event loop after a fork</a></li> 69<li><a href="#code_ev_fork_code_the_audacity_to_re"><code>ev_fork</code> - the audacity to resume the event loop after a fork</a>
70<ul><li><a href="#Watcher_Specific_Functions_and_Data_-10">Watcher-Specific Functions and Data Members</a></li>
71</ul>
72</li>
42</ul> 73</ul>
43</li> 74</li>
44<li><a href="#OTHER_FUNCTIONS">OTHER FUNCTIONS</a></li> 75<li><a href="#OTHER_FUNCTIONS">OTHER FUNCTIONS</a></li>
45<li><a href="#LIBEVENT_EMULATION">LIBEVENT EMULATION</a></li> 76<li><a href="#LIBEVENT_EMULATION">LIBEVENT EMULATION</a></li>
46<li><a href="#C_SUPPORT">C++ SUPPORT</a></li> 77<li><a href="#C_SUPPORT">C++ SUPPORT</a></li>
… …
941<p>If you cannot run the fd in non-blocking mode (for example you should not 972<p>If you cannot run the fd in non-blocking mode (for example you should not
942play around with an Xlib connection), then you have to seperately re-test 973play around with an Xlib connection), then you have to seperately re-test
943whether a file descriptor is really ready with a known-to-be good interface 974whether a file descriptor is really ready with a known-to-be good interface
944such as poll (fortunately in our Xlib example, Xlib already does this on 975such as poll (fortunately in our Xlib example, Xlib already does this on
945its own, so its quite safe to use).</p> 976its own, so its quite safe to use).</p>
977
978</div>
979<h3 id="The_special_problem_of_disappearing_">The special problem of disappearing file descriptors</h3>
980<div id="The_special_problem_of_disappearing_-2">
981<p>Some backends (e.g kqueue, epoll) need to be told about closing a file
982descriptor (either by calling <code>close</code> explicitly or by any other means,
983such as <code>dup</code>). The reason is that you register interest in some file
984descriptor, but when it goes away, the operating system will silently drop
985this interest. If another file descriptor with the same number then is
986registered with libev, there is no efficient way to see that this is, in
987fact, a different file descriptor.</p>
988<p>To avoid having to explicitly tell libev about such cases, libev follows
989the following policy: Each time <code>ev_io_set</code> is being called, libev
990will assume that this is potentially a new file descriptor, otherwise
991it is assumed that the file descriptor stays the same. That means that
992you <i>have</i> to call <code>ev_io_set</code> (or <code>ev_io_init</code>) when you change the
993descriptor even if the file descriptor number itself did not change.</p>
994<p>This is how one would do it normally anyway, the important point is that
995the libev application should not optimise around libev but should leave
996optimisations to libev.</p>
997
998
999
1000
1001
1002</div>
1003<h3 id="Watcher_Specific_Functions">Watcher-Specific Functions</h3>
1004<div id="Watcher_Specific_Functions_CONTENT">
946<dl> 1005<dl>
947 <dt>ev_io_init (ev_io *, callback, int fd, int events)</dt> 1006 <dt>ev_io_init (ev_io *, callback, int fd, int events)</dt>
948 <dt>ev_io_set (ev_io *, int fd, int events)</dt> 1007 <dt>ev_io_set (ev_io *, int fd, int events)</dt>
949 <dd> 1008 <dd>
950 <p>Configures an <code>ev_io</code> watcher. The <code>fd</code> is the file descriptor to 1009 <p>Configures an <code>ev_io</code> watcher. The <code>fd</code> is the file descriptor to
… …
1001 1060
1002</pre> 1061</pre>
1003<p>The callback is guarenteed to be invoked only when its timeout has passed, 1062<p>The callback is guarenteed to be invoked only when its timeout has passed,
1004but if multiple timers become ready during the same loop iteration then 1063but if multiple timers become ready during the same loop iteration then
1005order of execution is undefined.</p> 1064order of execution is undefined.</p>
1065
1066</div>
1067<h3 id="Watcher_Specific_Functions_and_Data_">Watcher-Specific Functions and Data Members</h3>
1068<div id="Watcher_Specific_Functions_and_Data_-2">
1006<dl> 1069<dl>
1007 <dt>ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)</dt> 1070 <dt>ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)</dt>
1008 <dt>ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)</dt> 1071 <dt>ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)</dt>
1009 <dd> 1072 <dd>
1010 <p>Configure the timer to trigger after <code>after</code> seconds. If <code>repeat</code> is 1073 <p>Configure the timer to trigger after <code>after</code> seconds. If <code>repeat</code> is
… …
1106triggering an event on each midnight, local time or other, complicated, 1169triggering an event on each midnight, local time or other, complicated,
1107rules.</p> 1170rules.</p>
1108<p>As with timers, the callback is guarenteed to be invoked only when the 1171<p>As with timers, the callback is guarenteed to be invoked only when the
1109time (<code>at</code>) has been passed, but if multiple periodic timers become ready 1172time (<code>at</code>) has been passed, but if multiple periodic timers become ready
1110during the same loop iteration then order of execution is undefined.</p> 1173during the same loop iteration then order of execution is undefined.</p>
1174
1175</div>
1176<h3 id="Watcher_Specific_Functions_and_Data_-3">Watcher-Specific Functions and Data Members</h3>
1177<div id="Watcher_Specific_Functions_and_Data_-2">
1111<dl> 1178<dl>
1112 <dt>ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)</dt> 1179 <dt>ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)</dt>
1113 <dt>ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)</dt> 1180 <dt>ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)</dt>
1114 <dd> 1181 <dd>
1115 <p>Lots of arguments, lets sort it out... There are basically three modes of 1182 <p>Lots of arguments, lets sort it out... There are basically three modes of
… …
1252first watcher gets started will libev actually register a signal watcher 1319first watcher gets started will libev actually register a signal watcher
1253with the kernel (thus it coexists with your own signal handlers as long 1320with the kernel (thus it coexists with your own signal handlers as long
1254as you don't register any with libev). Similarly, when the last signal 1321as you don't register any with libev). Similarly, when the last signal
1255watcher for a signal is stopped libev will reset the signal handler to 1322watcher for a signal is stopped libev will reset the signal handler to
1256SIG_DFL (regardless of what it was set to before).</p> 1323SIG_DFL (regardless of what it was set to before).</p>
1324
1325</div>
1326<h3 id="Watcher_Specific_Functions_and_Data_-4">Watcher-Specific Functions and Data Members</h3>
1327<div id="Watcher_Specific_Functions_and_Data_-2-2">
1257<dl> 1328<dl>
1258 <dt>ev_signal_init (ev_signal *, callback, int signum)</dt> 1329 <dt>ev_signal_init (ev_signal *, callback, int signum)</dt>
1259 <dt>ev_signal_set (ev_signal *, int signum)</dt> 1330 <dt>ev_signal_set (ev_signal *, int signum)</dt>
1260 <dd> 1331 <dd>
1261 <p>Configures the watcher to trigger on the given signal number (usually one 1332 <p>Configures the watcher to trigger on the given signal number (usually one
… …
1274</div> 1345</div>
1275<h2 id="code_ev_child_code_watch_out_for_pro"><code>ev_child</code> - watch out for process status changes</h2> 1346<h2 id="code_ev_child_code_watch_out_for_pro"><code>ev_child</code> - watch out for process status changes</h2>
1276<div id="code_ev_child_code_watch_out_for_pro-2"> 1347<div id="code_ev_child_code_watch_out_for_pro-2">
1277<p>Child watchers trigger when your process receives a SIGCHLD in response to 1348<p>Child watchers trigger when your process receives a SIGCHLD in response to
1278some child status changes (most typically when a child of yours dies).</p> 1349some child status changes (most typically when a child of yours dies).</p>
1350
1351</div>
1352<h3 id="Watcher_Specific_Functions_and_Data_-5">Watcher-Specific Functions and Data Members</h3>
1353<div id="Watcher_Specific_Functions_and_Data_-2-3">
1279<dl> 1354<dl>
1280 <dt>ev_child_init (ev_child *, callback, int pid)</dt> 1355 <dt>ev_child_init (ev_child *, callback, int pid)</dt>
1281 <dt>ev_child_set (ev_child *, int pid)</dt> 1356 <dt>ev_child_set (ev_child *, int pid)</dt>
1282 <dd> 1357 <dd>
1283 <p>Configures the watcher to wait for status changes of process <code>pid</code> (or 1358 <p>Configures the watcher to wait for status changes of process <code>pid</code> (or
… …
1346reader). Inotify will be used to give hints only and should not change the 1421reader). Inotify will be used to give hints only and should not change the
1347semantics of <code>ev_stat</code> watchers, which means that libev sometimes needs 1422semantics of <code>ev_stat</code> watchers, which means that libev sometimes needs
1348to fall back to regular polling again even with inotify, but changes are 1423to fall back to regular polling again even with inotify, but changes are
1349usually detected immediately, and if the file exists there will be no 1424usually detected immediately, and if the file exists there will be no
1350polling.</p> 1425polling.</p>
1426
1427</div>
1428<h3 id="Watcher_Specific_Functions_and_Data_-6">Watcher-Specific Functions and Data Members</h3>
1429<div id="Watcher_Specific_Functions_and_Data_-2-4">
1351<dl> 1430<dl>
1352 <dt>ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)</dt> 1431 <dt>ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)</dt>
1353 <dt>ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)</dt> 1432 <dt>ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)</dt>
1354 <dd> 1433 <dd>
1355 <p>Configures the watcher to wait for status changes of the given 1434 <p>Configures the watcher to wait for status changes of the given
… …
1433active, the process will not block when waiting for new events.</p> 1512active, the process will not block when waiting for new events.</p>
1434<p>Apart from keeping your process non-blocking (which is a useful 1513<p>Apart from keeping your process non-blocking (which is a useful
1435effect on its own sometimes), idle watchers are a good place to do 1514effect on its own sometimes), idle watchers are a good place to do
1436&quot;pseudo-background processing&quot;, or delay processing stuff to after the 1515&quot;pseudo-background processing&quot;, or delay processing stuff to after the
1437event loop has handled all outstanding events.</p> 1516event loop has handled all outstanding events.</p>
1517
1518</div>
1519<h3 id="Watcher_Specific_Functions_and_Data_-7">Watcher-Specific Functions and Data Members</h3>
1520<div id="Watcher_Specific_Functions_and_Data_-2-5">
1438<dl> 1521<dl>
1439 <dt>ev_idle_init (ev_signal *, callback)</dt> 1522 <dt>ev_idle_init (ev_signal *, callback)</dt>
1440 <dd> 1523 <dd>
1441 <p>Initialises and configures the idle watcher - it has no parameters of any 1524 <p>Initialises and configures the idle watcher - it has no parameters of any
1442kind. There is a <code>ev_idle_set</code> macro, but using it is utterly pointless, 1525kind. There is a <code>ev_idle_set</code> macro, but using it is utterly pointless,
… …
1505supports this, they will be called before other <code>ev_check</code> watchers did 1588supports this, they will be called before other <code>ev_check</code> watchers did
1506their job. As <code>ev_check</code> watchers are often used to embed other event 1589their job. As <code>ev_check</code> watchers are often used to embed other event
1507loops those other event loops might be in an unusable state until their 1590loops those other event loops might be in an unusable state until their
1508<code>ev_check</code> watcher ran (always remind yourself to coexist peacefully with 1591<code>ev_check</code> watcher ran (always remind yourself to coexist peacefully with
1509others).</p> 1592others).</p>
1593
1594</div>
1595<h3 id="Watcher_Specific_Functions_and_Data_-8">Watcher-Specific Functions and Data Members</h3>
1596<div id="Watcher_Specific_Functions_and_Data_-2-6">
1510<dl> 1597<dl>
1511 <dt>ev_prepare_init (ev_prepare *, callback)</dt> 1598 <dt>ev_prepare_init (ev_prepare *, callback)</dt>
1512 <dt>ev_check_init (ev_check *, callback)</dt> 1599 <dt>ev_check_init (ev_check *, callback)</dt>
1513 <dd> 1600 <dd>
1514 <p>Initialises and configures the prepare or check watcher - they have no 1601 <p>Initialises and configures the prepare or check watcher - they have no
… …
1706 } 1793 }
1707 else 1794 else
1708 loop_lo = loop_hi; 1795 loop_lo = loop_hi;
1709 1796
1710</pre> 1797</pre>
1798
1799</div>
1800<h3 id="Watcher_Specific_Functions_and_Data_-9">Watcher-Specific Functions and Data Members</h3>
1801<div id="Watcher_Specific_Functions_and_Data_-2-7">
1711<dl> 1802<dl>
1712 <dt>ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)</dt> 1803 <dt>ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)</dt>
1713 <dt>ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)</dt> 1804 <dt>ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)</dt>
1714 <dd> 1805 <dd>
1715 <p>Configures the watcher to embed the given loop, which must be 1806 <p>Configures the watcher to embed the given loop, which must be
… …
1742<code>ev_default_fork</code> or <code>ev_loop_fork</code>). The invocation is done before the 1833<code>ev_default_fork</code> or <code>ev_loop_fork</code>). The invocation is done before the
1743event loop blocks next and before <code>ev_check</code> watchers are being called, 1834event loop blocks next and before <code>ev_check</code> watchers are being called,
1744and only in the child after the fork. If whoever good citizen calling 1835and only in the child after the fork. If whoever good citizen calling
1745<code>ev_default_fork</code> cheats and calls it in the wrong process, the fork 1836<code>ev_default_fork</code> cheats and calls it in the wrong process, the fork
1746handlers will be invoked, too, of course.</p> 1837handlers will be invoked, too, of course.</p>
1838
1839</div>
1840<h3 id="Watcher_Specific_Functions_and_Data_-10">Watcher-Specific Functions and Data Members</h3>
1841<div id="Watcher_Specific_Functions_and_Data_-2-8">
1747<dl> 1842<dl>
1748 <dt>ev_fork_init (ev_signal *, callback)</dt> 1843 <dt>ev_fork_init (ev_signal *, callback)</dt>
1749 <dd> 1844 <dd>
1750 <p>Initialises and configures the fork watcher - it has no parameters of any 1845 <p>Initialises and configures the fork watcher - it has no parameters of any
1751kind. There is a <code>ev_fork_set</code> macro, but using it is utterly pointless, 1846kind. There is a <code>ev_fork_set</code> macro, but using it is utterly pointless,

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