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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 20:30:11 2007" /> 9 <meta name="created" content="Wed Dec 12 18:55:04 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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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></li>
42</ul> 70</ul>
43</li> 71</li>
44<li><a href="#OTHER_FUNCTIONS">OTHER FUNCTIONS</a></li> 72<li><a href="#OTHER_FUNCTIONS">OTHER FUNCTIONS</a></li>
45<li><a href="#LIBEVENT_EMULATION">LIBEVENT EMULATION</a></li> 73<li><a href="#LIBEVENT_EMULATION">LIBEVENT EMULATION</a></li>
… …
185you actually want to know.</p> 213you actually want to know.</p>
186 </dd> 214 </dd>
187 <dt>int ev_version_major ()</dt> 215 <dt>int ev_version_major ()</dt>
188 <dt>int ev_version_minor ()</dt> 216 <dt>int ev_version_minor ()</dt>
189 <dd> 217 <dd>
190 <p>You can find out the major and minor version numbers of the library 218 <p>You can find out the major and minor ABI version numbers of the library
191you linked against by calling the functions <code>ev_version_major</code> and 219you linked against by calling the functions <code>ev_version_major</code> and
192<code>ev_version_minor</code>. If you want, you can compare against the global 220<code>ev_version_minor</code>. If you want, you can compare against the global
193symbols <code>EV_VERSION_MAJOR</code> and <code>EV_VERSION_MINOR</code>, which specify the 221symbols <code>EV_VERSION_MAJOR</code> and <code>EV_VERSION_MINOR</code>, which specify the
194version of the library your program was compiled against.</p> 222version of the library your program was compiled against.</p>
223 <p>These version numbers refer to the ABI version of the library, not the
224release version.</p>
195 <p>Usually, it's a good idea to terminate if the major versions mismatch, 225 <p>Usually, it's a good idea to terminate if the major versions mismatch,
196as this indicates an incompatible change. Minor versions are usually 226as this indicates an incompatible change. Minor versions are usually
197compatible to older versions, so a larger minor version alone is usually 227compatible to older versions, so a larger minor version alone is usually
198not a problem.</p> 228not a problem.</p>
199 <p>Example: Make sure we haven't accidentally been linked against the wrong 229 <p>Example: Make sure we haven't accidentally been linked against the wrong
200version.</p> 230version.</p>
201<pre> assert ((&quot;libev version mismatch&quot;, 231<pre> assert ((&quot;libev version mismatch&quot;,
… …
939<p>If you cannot run the fd in non-blocking mode (for example you should not 969<p>If you cannot run the fd in non-blocking mode (for example you should not
940play around with an Xlib connection), then you have to seperately re-test 970play around with an Xlib connection), then you have to seperately re-test
941whether a file descriptor is really ready with a known-to-be good interface 971whether a file descriptor is really ready with a known-to-be good interface
942such as poll (fortunately in our Xlib example, Xlib already does this on 972such as poll (fortunately in our Xlib example, Xlib already does this on
943its own, so its quite safe to use).</p> 973its own, so its quite safe to use).</p>
974
975</div>
976<h3 id="The_special_problem_of_disappearing_">The special problem of disappearing file descriptors</h3>
977<div id="The_special_problem_of_disappearing_-2">
978<p>Some backends (e.g kqueue, epoll) need to be told about closing a file
979descriptor (either by calling <code>close</code> explicitly or by any other means,
980such as <code>dup</code>). The reason is that you register interest in some file
981descriptor, but when it goes away, the operating system will silently drop
982this interest. If another file descriptor with the same number then is
983registered with libev, there is no efficient way to see that this is, in
984fact, a different file descriptor.</p>
985<p>To avoid having to explicitly tell libev about such cases, libev follows
986the following policy: Each time <code>ev_io_set</code> is being called, libev
987will assume that this is potentially a new file descriptor, otherwise
988it is assumed that the file descriptor stays the same. That means that
989you <i>have</i> to call <code>ev_io_set</code> (or <code>ev_io_init</code>) when you change the
990descriptor even if the file descriptor number itself did not change.</p>
991<p>This is how one would do it normally anyway, the important point is that
992the libev application should not optimise around libev but should leave
993optimisations to libev.</p>
994
995
996
997
998
999</div>
1000<h3 id="Watcher_Specific_Functions">Watcher-Specific Functions</h3>
1001<div id="Watcher_Specific_Functions_CONTENT">
944<dl> 1002<dl>
945 <dt>ev_io_init (ev_io *, callback, int fd, int events)</dt> 1003 <dt>ev_io_init (ev_io *, callback, int fd, int events)</dt>
946 <dt>ev_io_set (ev_io *, int fd, int events)</dt> 1004 <dt>ev_io_set (ev_io *, int fd, int events)</dt>
947 <dd> 1005 <dd>
948 <p>Configures an <code>ev_io</code> watcher. The <code>fd</code> is the file descriptor to 1006 <p>Configures an <code>ev_io</code> watcher. The <code>fd</code> is the file descriptor to
… …
999 1057
1000</pre> 1058</pre>
1001<p>The callback is guarenteed to be invoked only when its timeout has passed, 1059<p>The callback is guarenteed to be invoked only when its timeout has passed,
1002but if multiple timers become ready during the same loop iteration then 1060but if multiple timers become ready during the same loop iteration then
1003order of execution is undefined.</p> 1061order of execution is undefined.</p>
1062
1063</div>
1064<h3 id="Watcher_Specific_Functions_and_Data_">Watcher-Specific Functions and Data Members</h3>
1065<div id="Watcher_Specific_Functions_and_Data_-2">
1004<dl> 1066<dl>
1005 <dt>ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)</dt> 1067 <dt>ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)</dt>
1006 <dt>ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)</dt> 1068 <dt>ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)</dt>
1007 <dd> 1069 <dd>
1008 <p>Configure the timer to trigger after <code>after</code> seconds. If <code>repeat</code> is 1070 <p>Configure the timer to trigger after <code>after</code> seconds. If <code>repeat</code> is
… …
1104triggering an event on each midnight, local time or other, complicated, 1166triggering an event on each midnight, local time or other, complicated,
1105rules.</p> 1167rules.</p>
1106<p>As with timers, the callback is guarenteed to be invoked only when the 1168<p>As with timers, the callback is guarenteed to be invoked only when the
1107time (<code>at</code>) has been passed, but if multiple periodic timers become ready 1169time (<code>at</code>) has been passed, but if multiple periodic timers become ready
1108during the same loop iteration then order of execution is undefined.</p> 1170during the same loop iteration then order of execution is undefined.</p>
1171
1172</div>
1173<h3 id="Watcher_Specific_Functions_and_Data_-3">Watcher-Specific Functions and Data Members</h3>
1174<div id="Watcher_Specific_Functions_and_Data_-2">
1109<dl> 1175<dl>
1110 <dt>ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)</dt> 1176 <dt>ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)</dt>
1111 <dt>ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)</dt> 1177 <dt>ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)</dt>
1112 <dd> 1178 <dd>
1113 <p>Lots of arguments, lets sort it out... There are basically three modes of 1179 <p>Lots of arguments, lets sort it out... There are basically three modes of
… …
1250first watcher gets started will libev actually register a signal watcher 1316first watcher gets started will libev actually register a signal watcher
1251with the kernel (thus it coexists with your own signal handlers as long 1317with the kernel (thus it coexists with your own signal handlers as long
1252as you don't register any with libev). Similarly, when the last signal 1318as you don't register any with libev). Similarly, when the last signal
1253watcher for a signal is stopped libev will reset the signal handler to 1319watcher for a signal is stopped libev will reset the signal handler to
1254SIG_DFL (regardless of what it was set to before).</p> 1320SIG_DFL (regardless of what it was set to before).</p>
1321
1322</div>
1323<h3 id="Watcher_Specific_Functions_and_Data_-4">Watcher-Specific Functions and Data Members</h3>
1324<div id="Watcher_Specific_Functions_and_Data_-2-2">
1255<dl> 1325<dl>
1256 <dt>ev_signal_init (ev_signal *, callback, int signum)</dt> 1326 <dt>ev_signal_init (ev_signal *, callback, int signum)</dt>
1257 <dt>ev_signal_set (ev_signal *, int signum)</dt> 1327 <dt>ev_signal_set (ev_signal *, int signum)</dt>
1258 <dd> 1328 <dd>
1259 <p>Configures the watcher to trigger on the given signal number (usually one 1329 <p>Configures the watcher to trigger on the given signal number (usually one
… …
1272</div> 1342</div>
1273<h2 id="code_ev_child_code_watch_out_for_pro"><code>ev_child</code> - watch out for process status changes</h2> 1343<h2 id="code_ev_child_code_watch_out_for_pro"><code>ev_child</code> - watch out for process status changes</h2>
1274<div id="code_ev_child_code_watch_out_for_pro-2"> 1344<div id="code_ev_child_code_watch_out_for_pro-2">
1275<p>Child watchers trigger when your process receives a SIGCHLD in response to 1345<p>Child watchers trigger when your process receives a SIGCHLD in response to
1276some child status changes (most typically when a child of yours dies).</p> 1346some child status changes (most typically when a child of yours dies).</p>
1347
1348</div>
1349<h3 id="Watcher_Specific_Functions_and_Data_-5">Watcher-Specific Functions and Data Members</h3>
1350<div id="Watcher_Specific_Functions_and_Data_-2-3">
1277<dl> 1351<dl>
1278 <dt>ev_child_init (ev_child *, callback, int pid)</dt> 1352 <dt>ev_child_init (ev_child *, callback, int pid)</dt>
1279 <dt>ev_child_set (ev_child *, int pid)</dt> 1353 <dt>ev_child_set (ev_child *, int pid)</dt>
1280 <dd> 1354 <dd>
1281 <p>Configures the watcher to wait for status changes of process <code>pid</code> (or 1355 <p>Configures the watcher to wait for status changes of process <code>pid</code> (or
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1344reader). Inotify will be used to give hints only and should not change the 1418reader). Inotify will be used to give hints only and should not change the
1345semantics of <code>ev_stat</code> watchers, which means that libev sometimes needs 1419semantics of <code>ev_stat</code> watchers, which means that libev sometimes needs
1346to fall back to regular polling again even with inotify, but changes are 1420to fall back to regular polling again even with inotify, but changes are
1347usually detected immediately, and if the file exists there will be no 1421usually detected immediately, and if the file exists there will be no
1348polling.</p> 1422polling.</p>
1423
1424</div>
1425<h3 id="Watcher_Specific_Functions_and_Data_-6">Watcher-Specific Functions and Data Members</h3>
1426<div id="Watcher_Specific_Functions_and_Data_-2-4">
1349<dl> 1427<dl>
1350 <dt>ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)</dt> 1428 <dt>ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)</dt>
1351 <dt>ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)</dt> 1429 <dt>ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)</dt>
1352 <dd> 1430 <dd>
1353 <p>Configures the watcher to wait for status changes of the given 1431 <p>Configures the watcher to wait for status changes of the given
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1431active, the process will not block when waiting for new events.</p> 1509active, the process will not block when waiting for new events.</p>
1432<p>Apart from keeping your process non-blocking (which is a useful 1510<p>Apart from keeping your process non-blocking (which is a useful
1433effect on its own sometimes), idle watchers are a good place to do 1511effect on its own sometimes), idle watchers are a good place to do
1434&quot;pseudo-background processing&quot;, or delay processing stuff to after the 1512&quot;pseudo-background processing&quot;, or delay processing stuff to after the
1435event loop has handled all outstanding events.</p> 1513event loop has handled all outstanding events.</p>
1514
1515</div>
1516<h3 id="Watcher_Specific_Functions_and_Data_-7">Watcher-Specific Functions and Data Members</h3>
1517<div id="Watcher_Specific_Functions_and_Data_-2-5">
1436<dl> 1518<dl>
1437 <dt>ev_idle_init (ev_signal *, callback)</dt> 1519 <dt>ev_idle_init (ev_signal *, callback)</dt>
1438 <dd> 1520 <dd>
1439 <p>Initialises and configures the idle watcher - it has no parameters of any 1521 <p>Initialises and configures the idle watcher - it has no parameters of any
1440kind. There is a <code>ev_idle_set</code> macro, but using it is utterly pointless, 1522kind. There is a <code>ev_idle_set</code> macro, but using it is utterly pointless,
… …
1503supports this, they will be called before other <code>ev_check</code> watchers did 1585supports this, they will be called before other <code>ev_check</code> watchers did
1504their job. As <code>ev_check</code> watchers are often used to embed other event 1586their job. As <code>ev_check</code> watchers are often used to embed other event
1505loops those other event loops might be in an unusable state until their 1587loops those other event loops might be in an unusable state until their
1506<code>ev_check</code> watcher ran (always remind yourself to coexist peacefully with 1588<code>ev_check</code> watcher ran (always remind yourself to coexist peacefully with
1507others).</p> 1589others).</p>
1590
1591</div>
1592<h3 id="Watcher_Specific_Functions_and_Data_-8">Watcher-Specific Functions and Data Members</h3>
1593<div id="Watcher_Specific_Functions_and_Data_-2-6">
1508<dl> 1594<dl>
1509 <dt>ev_prepare_init (ev_prepare *, callback)</dt> 1595 <dt>ev_prepare_init (ev_prepare *, callback)</dt>
1510 <dt>ev_check_init (ev_check *, callback)</dt> 1596 <dt>ev_check_init (ev_check *, callback)</dt>
1511 <dd> 1597 <dd>
1512 <p>Initialises and configures the prepare or check watcher - they have no 1598 <p>Initialises and configures the prepare or check watcher - they have no
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1704 } 1790 }
1705 else 1791 else
1706 loop_lo = loop_hi; 1792 loop_lo = loop_hi;
1707 1793
1708</pre> 1794</pre>
1795
1796</div>
1797<h3 id="Watcher_Specific_Functions_and_Data_-9">Watcher-Specific Functions and Data Members</h3>
1798<div id="Watcher_Specific_Functions_and_Data_-2-7">
1709<dl> 1799<dl>
1710 <dt>ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)</dt> 1800 <dt>ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)</dt>
1711 <dt>ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)</dt> 1801 <dt>ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)</dt>
1712 <dd> 1802 <dd>
1713 <p>Configures the watcher to embed the given loop, which must be 1803 <p>Configures the watcher to embed the given loop, which must be

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