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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="Tue Nov 27 20:38:24 2007" /> 9 <meta name="created" content="Wed Nov 28 12:27:27 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 -->
15<h3 id="TOP">Index</h3> 15<h3 id="TOP">Index</h3>
16 16
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="#EXAMPLE_PROGRAM">EXAMPLE PROGRAM</a></li>
19<li><a href="#DESCRIPTION">DESCRIPTION</a></li> 20<li><a href="#DESCRIPTION">DESCRIPTION</a></li>
20<li><a href="#FEATURES">FEATURES</a></li> 21<li><a href="#FEATURES">FEATURES</a></li>
21<li><a href="#CONVENTIONS">CONVENTIONS</a></li> 22<li><a href="#CONVENTIONS">CONVENTIONS</a></li>
22<li><a href="#TIME_REPRESENTATION">TIME REPRESENTATION</a></li> 23<li><a href="#TIME_REPRESENTATION">TIME REPRESENTATION</a></li>
23<li><a href="#GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</a></li> 24<li><a href="#GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</a></li>
… …
59<li><a href="#AUTHOR">AUTHOR</a> 60<li><a href="#AUTHOR">AUTHOR</a>
60</li> 61</li>
61</ul><hr /> 62</ul><hr />
62<!-- INDEX END --> 63<!-- INDEX END -->
63 64
64<h1 id="NAME">NAME</h1><p><a href="#TOP" class="toplink">Top</a></p> 65<h1 id="NAME">NAME</h1>
65<div id="NAME_CONTENT"> 66<div id="NAME_CONTENT">
66<p>libev - a high performance full-featured event loop written in C</p> 67<p>libev - a high performance full-featured event loop written in C</p>
67 68
68</div> 69</div>
69<h1 id="SYNOPSIS">SYNOPSIS</h1><p><a href="#TOP" class="toplink">Top</a></p> 70<h1 id="SYNOPSIS">SYNOPSIS</h1>
70<div id="SYNOPSIS_CONTENT"> 71<div id="SYNOPSIS_CONTENT">
71<pre> #include &lt;ev.h&gt; 72<pre> #include &lt;ev.h&gt;
72 73
73</pre> 74</pre>
74 75
75</div> 76</div>
76<h1 id="DESCRIPTION">DESCRIPTION</h1><p><a href="#TOP" class="toplink">Top</a></p> 77<h1 id="EXAMPLE_PROGRAM">EXAMPLE PROGRAM</h1>
78<div id="EXAMPLE_PROGRAM_CONTENT">
79<pre> #include &lt;ev.h&gt;
80
81 ev_io stdin_watcher;
82 ev_timer timeout_watcher;
83
84 /* called when data readable on stdin */
85 static void
86 stdin_cb (EV_P_ struct ev_io *w, int revents)
87 {
88 /* puts (&quot;stdin ready&quot;); */
89 ev_io_stop (EV_A_ w); /* just a syntax example */
90 ev_unloop (EV_A_ EVUNLOOP_ALL); /* leave all loop calls */
91 }
92
93 static void
94 timeout_cb (EV_P_ struct ev_timer *w, int revents)
95 {
96 /* puts (&quot;timeout&quot;); */
97 ev_unloop (EV_A_ EVUNLOOP_ONE); /* leave one loop call */
98 }
99
100 int
101 main (void)
102 {
103 struct ev_loop *loop = ev_default_loop (0);
104
105 /* initialise an io watcher, then start it */
106 ev_io_init (&amp;stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ);
107 ev_io_start (loop, &amp;stdin_watcher);
108
109 /* simple non-repeating 5.5 second timeout */
110 ev_timer_init (&amp;timeout_watcher, timeout_cb, 5.5, 0.);
111 ev_timer_start (loop, &amp;timeout_watcher);
112
113 /* loop till timeout or data ready */
114 ev_loop (loop, 0);
115
116 return 0;
117 }
118
119</pre>
120
121</div>
122<h1 id="DESCRIPTION">DESCRIPTION</h1>
77<div id="DESCRIPTION_CONTENT"> 123<div id="DESCRIPTION_CONTENT">
78<p>Libev is an event loop: you register interest in certain events (such as a 124<p>Libev is an event loop: you register interest in certain events (such as a
79file descriptor being readable or a timeout occuring), and it will manage 125file descriptor being readable or a timeout occuring), and it will manage
80these event sources and provide your program with events.</p> 126these event sources and provide your program with events.</p>
81<p>To do this, it must take more or less complete control over your process 127<p>To do this, it must take more or less complete control over your process
… …
85watchers</i>, which are relatively small C structures you initialise with the 131watchers</i>, which are relatively small C structures you initialise with the
86details of the event, and then hand it over to libev by <i>starting</i> the 132details of the event, and then hand it over to libev by <i>starting</i> the
87watcher.</p> 133watcher.</p>
88 134
89</div> 135</div>
90<h1 id="FEATURES">FEATURES</h1><p><a href="#TOP" class="toplink">Top</a></p> 136<h1 id="FEATURES">FEATURES</h1>
91<div id="FEATURES_CONTENT"> 137<div id="FEATURES_CONTENT">
92<p>Libev supports select, poll, the linux-specific epoll and the bsd-specific 138<p>Libev supports <code>select</code>, <code>poll</code>, the linux-specific <code>epoll</code>, the
93kqueue mechanisms for file descriptor events, relative timers, absolute 139bsd-specific <code>kqueue</code> and the solaris-specific event port mechanisms
94timers with customised rescheduling, signal events, process status change 140for file descriptor events (<code>ev_io</code>), relative timers (<code>ev_timer</code>),
95events (related to SIGCHLD), and event watchers dealing with the event 141absolute timers with customised rescheduling (<code>ev_periodic</code>), synchronous
96loop mechanism itself (idle, prepare and check watchers). It also is quite 142signals (<code>ev_signal</code>), process status change events (<code>ev_child</code>), and
143event watchers dealing with the event loop mechanism itself (<code>ev_idle</code>,
144<code>ev_embed</code>, <code>ev_prepare</code> and <code>ev_check</code> watchers) as well as
145file watchers (<code>ev_stat</code>) and even limited support for fork events
146(<code>ev_fork</code>).</p>
147<p>It also is quite fast (see this
97fast (see this <a href="http://libev.schmorp.de/bench.html">benchmark</a> comparing 148<a href="http://libev.schmorp.de/bench.html">benchmark</a> comparing it to libevent
98it to libevent for example).</p> 149for example).</p>
99 150
100</div> 151</div>
101<h1 id="CONVENTIONS">CONVENTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p> 152<h1 id="CONVENTIONS">CONVENTIONS</h1>
102<div id="CONVENTIONS_CONTENT"> 153<div id="CONVENTIONS_CONTENT">
103<p>Libev is very configurable. In this manual the default configuration 154<p>Libev is very configurable. In this manual the default configuration will
104will be described, which supports multiple event loops. For more info 155be described, which supports multiple event loops. For more info about
105about various configuration options please have a look at the file 156various configuration options please have a look at <strong>EMBED</strong> section in
106<cite>README.embed</cite> in the libev distribution. If libev was configured without 157this manual. If libev was configured without support for multiple event
107support for multiple event loops, then all functions taking an initial 158loops, then all functions taking an initial argument of name <code>loop</code>
108argument of name <code>loop</code> (which is always of type <code>struct ev_loop *</code>) 159(which is always of type <code>struct ev_loop *</code>) will not have this argument.</p>
109will not have this argument.</p>
110 160
111</div> 161</div>
112<h1 id="TIME_REPRESENTATION">TIME REPRESENTATION</h1><p><a href="#TOP" class="toplink">Top</a></p> 162<h1 id="TIME_REPRESENTATION">TIME REPRESENTATION</h1>
113<div id="TIME_REPRESENTATION_CONTENT"> 163<div id="TIME_REPRESENTATION_CONTENT">
114<p>Libev represents time as a single floating point number, representing the 164<p>Libev represents time as a single floating point number, representing the
115(fractional) number of seconds since the (POSIX) epoch (somewhere near 165(fractional) number of seconds since the (POSIX) epoch (somewhere near
116the beginning of 1970, details are complicated, don't ask). This type is 166the beginning of 1970, details are complicated, don't ask). This type is
117called <code>ev_tstamp</code>, which is what you should use too. It usually aliases 167called <code>ev_tstamp</code>, which is what you should use too. It usually aliases
118to the <code>double</code> type in C, and when you need to do any calculations on 168to the <code>double</code> type in C, and when you need to do any calculations on
119it, you should treat it as such.</p> 169it, you should treat it as such.</p>
120 170
121</div> 171</div>
122<h1 id="GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p> 172<h1 id="GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</h1>
123<div id="GLOBAL_FUNCTIONS_CONTENT"> 173<div id="GLOBAL_FUNCTIONS_CONTENT">
124<p>These functions can be called anytime, even before initialising the 174<p>These functions can be called anytime, even before initialising the
125library in any way.</p> 175library in any way.</p>
126<dl> 176<dl>
127 <dt>ev_tstamp ev_time ()</dt> 177 <dt>ev_tstamp ev_time ()</dt>
… …
140version of the library your program was compiled against.</p> 190version of the library your program was compiled against.</p>
141 <p>Usually, it's a good idea to terminate if the major versions mismatch, 191 <p>Usually, it's a good idea to terminate if the major versions mismatch,
142as this indicates an incompatible change. Minor versions are usually 192as this indicates an incompatible change. Minor versions are usually
143compatible to older versions, so a larger minor version alone is usually 193compatible to older versions, so a larger minor version alone is usually
144not a problem.</p> 194not a problem.</p>
145 <p>Example: make sure we haven't accidentally been linked against the wrong 195 <p>Example: Make sure we haven't accidentally been linked against the wrong
146version:</p> 196version.</p>
147<pre> assert ((&quot;libev version mismatch&quot;, 197<pre> assert ((&quot;libev version mismatch&quot;,
148 ev_version_major () == EV_VERSION_MAJOR 198 ev_version_major () == EV_VERSION_MAJOR
149 &amp;&amp; ev_version_minor () &gt;= EV_VERSION_MINOR)); 199 &amp;&amp; ev_version_minor () &gt;= EV_VERSION_MINOR));
150 200
151</pre> 201</pre>
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189allocated, the library might abort or take some potentially destructive 239allocated, the library might abort or take some potentially destructive
190action. The default is your system realloc function.</p> 240action. The default is your system realloc function.</p>
191 <p>You could override this function in high-availability programs to, say, 241 <p>You could override this function in high-availability programs to, say,
192free some memory if it cannot allocate memory, to use a special allocator, 242free some memory if it cannot allocate memory, to use a special allocator,
193or even to sleep a while and retry until some memory is available.</p> 243or even to sleep a while and retry until some memory is available.</p>
194 <p>Example: replace the libev allocator with one that waits a bit and then 244 <p>Example: Replace the libev allocator with one that waits a bit and then
195retries: better than mine).</p> 245retries).</p>
196<pre> static void * 246<pre> static void *
197 persistent_realloc (void *ptr, size_t size) 247 persistent_realloc (void *ptr, size_t size)
198 { 248 {
199 for (;;) 249 for (;;)
200 { 250 {
… …
219indicating the system call or subsystem causing the problem. If this 269indicating the system call or subsystem causing the problem. If this
220callback is set, then libev will expect it to remedy the sitution, no 270callback is set, then libev will expect it to remedy the sitution, no
221matter what, when it returns. That is, libev will generally retry the 271matter what, when it returns. That is, libev will generally retry the
222requested operation, or, if the condition doesn't go away, do bad stuff 272requested operation, or, if the condition doesn't go away, do bad stuff
223(such as abort).</p> 273(such as abort).</p>
224 <p>Example: do the same thing as libev does internally:</p> 274 <p>Example: This is basically the same thing that libev does internally, too.</p>
225<pre> static void 275<pre> static void
226 fatal_error (const char *msg) 276 fatal_error (const char *msg)
227 { 277 {
228 perror (msg); 278 perror (msg);
229 abort (); 279 abort ();
… …
235</pre> 285</pre>
236 </dd> 286 </dd>
237</dl> 287</dl>
238 288
239</div> 289</div>
240<h1 id="FUNCTIONS_CONTROLLING_THE_EVENT_LOOP">FUNCTIONS CONTROLLING THE EVENT LOOP</h1><p><a href="#TOP" class="toplink">Top</a></p> 290<h1 id="FUNCTIONS_CONTROLLING_THE_EVENT_LOOP">FUNCTIONS CONTROLLING THE EVENT LOOP</h1>
241<div id="FUNCTIONS_CONTROLLING_THE_EVENT_LOOP-2"> 291<div id="FUNCTIONS_CONTROLLING_THE_EVENT_LOOP-2">
242<p>An event loop is described by a <code>struct ev_loop *</code>. The library knows two 292<p>An event loop is described by a <code>struct ev_loop *</code>. The library knows two
243types of such loops, the <i>default</i> loop, which supports signals and child 293types of such loops, the <i>default</i> loop, which supports signals and child
244events, and dynamically created loops which do not.</p> 294events, and dynamically created loops which do not.</p>
245<p>If you use threads, a common model is to run the default event loop 295<p>If you use threads, a common model is to run the default event loop
… …
365 <dd> 415 <dd>
366 <p>Similar to <code>ev_default_loop</code>, but always creates a new event loop that is 416 <p>Similar to <code>ev_default_loop</code>, but always creates a new event loop that is
367always distinct from the default loop. Unlike the default loop, it cannot 417always distinct from the default loop. Unlike the default loop, it cannot
368handle signal and child watchers, and attempts to do so will be greeted by 418handle signal and child watchers, and attempts to do so will be greeted by
369undefined behaviour (or a failed assertion if assertions are enabled).</p> 419undefined behaviour (or a failed assertion if assertions are enabled).</p>
370 <p>Example: try to create a event loop that uses epoll and nothing else.</p> 420 <p>Example: Try to create a event loop that uses epoll and nothing else.</p>
371<pre> struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); 421<pre> struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);
372 if (!epoller) 422 if (!epoller)
373 fatal (&quot;no epoll found here, maybe it hides under your chair&quot;); 423 fatal (&quot;no epoll found here, maybe it hides under your chair&quot;);
374 424
375</pre> 425</pre>
… …
468 be handled here by queueing them when their watcher gets executed. 518 be handled here by queueing them when their watcher gets executed.
469 - If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK 519 - If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK
470 were used, return, otherwise continue with step *. 520 were used, return, otherwise continue with step *.
471 521
472</pre> 522</pre>
473 <p>Example: queue some jobs and then loop until no events are outsanding 523 <p>Example: Queue some jobs and then loop until no events are outsanding
474anymore.</p> 524anymore.</p>
475<pre> ... queue jobs here, make sure they register event watchers as long 525<pre> ... queue jobs here, make sure they register event watchers as long
476 ... as they still have work to do (even an idle watcher will do..) 526 ... as they still have work to do (even an idle watcher will do..)
477 ev_loop (my_loop, 0); 527 ev_loop (my_loop, 0);
478 ... jobs done. yeah! 528 ... jobs done. yeah!
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497example, libev itself uses this for its internal signal pipe: It is not 547example, libev itself uses this for its internal signal pipe: It is not
498visible to the libev user and should not keep <code>ev_loop</code> from exiting if 548visible to the libev user and should not keep <code>ev_loop</code> from exiting if
499no event watchers registered by it are active. It is also an excellent 549no event watchers registered by it are active. It is also an excellent
500way to do this for generic recurring timers or from within third-party 550way to do this for generic recurring timers or from within third-party
501libraries. Just remember to <i>unref after start</i> and <i>ref before stop</i>.</p> 551libraries. Just remember to <i>unref after start</i> and <i>ref before stop</i>.</p>
502 <p>Example: create a signal watcher, but keep it from keeping <code>ev_loop</code> 552 <p>Example: Create a signal watcher, but keep it from keeping <code>ev_loop</code>
503running when nothing else is active.</p> 553running when nothing else is active.</p>
504<pre> struct dv_signal exitsig; 554<pre> struct ev_signal exitsig;
505 ev_signal_init (&amp;exitsig, sig_cb, SIGINT); 555 ev_signal_init (&amp;exitsig, sig_cb, SIGINT);
506 ev_signal_start (myloop, &amp;exitsig); 556 ev_signal_start (loop, &amp;exitsig);
507 evf_unref (myloop); 557 evf_unref (loop);
508 558
509</pre> 559</pre>
510 <p>Example: for some weird reason, unregister the above signal handler again.</p> 560 <p>Example: For some weird reason, unregister the above signal handler again.</p>
511<pre> ev_ref (myloop); 561<pre> ev_ref (loop);
512 ev_signal_stop (myloop, &amp;exitsig); 562 ev_signal_stop (loop, &amp;exitsig);
513 563
514</pre> 564</pre>
515 </dd> 565 </dd>
516</dl> 566</dl>
517 567
518 568
519 569
520 570
521 571
522</div> 572</div>
523<h1 id="ANATOMY_OF_A_WATCHER">ANATOMY OF A WATCHER</h1><p><a href="#TOP" class="toplink">Top</a></p> 573<h1 id="ANATOMY_OF_A_WATCHER">ANATOMY OF A WATCHER</h1>
524<div id="ANATOMY_OF_A_WATCHER_CONTENT"> 574<div id="ANATOMY_OF_A_WATCHER_CONTENT">
525<p>A watcher is a structure that you create and register to record your 575<p>A watcher is a structure that you create and register to record your
526interest in some event. For instance, if you want to wait for STDIN to 576interest in some event. For instance, if you want to wait for STDIN to
527become readable, you would create an <code>ev_io</code> watcher for that:</p> 577become readable, you would create an <code>ev_io</code> watcher for that:</p>
528<pre> static void my_cb (struct ev_loop *loop, struct ev_io *w, int revents) 578<pre> static void my_cb (struct ev_loop *loop, struct ev_io *w, int revents)
… …
691events but its callback has not yet been invoked). As long as a watcher 741events but its callback has not yet been invoked). As long as a watcher
692is pending (but not active) you must not call an init function on it (but 742is pending (but not active) you must not call an init function on it (but
693<code>ev_TYPE_set</code> is safe) and you must make sure the watcher is available to 743<code>ev_TYPE_set</code> is safe) and you must make sure the watcher is available to
694libev (e.g. you cnanot <code>free ()</code> it).</p> 744libev (e.g. you cnanot <code>free ()</code> it).</p>
695 </dd> 745 </dd>
696 <dt>callback = ev_cb (ev_TYPE *watcher)</dt> 746 <dt>callback ev_cb (ev_TYPE *watcher)</dt>
697 <dd> 747 <dd>
698 <p>Returns the callback currently set on the watcher.</p> 748 <p>Returns the callback currently set on the watcher.</p>
699 </dd> 749 </dd>
700 <dt>ev_cb_set (ev_TYPE *watcher, callback)</dt> 750 <dt>ev_cb_set (ev_TYPE *watcher, callback)</dt>
701 <dd> 751 <dd>
… …
733 struct my_io *w = (struct my_io *)w_; 783 struct my_io *w = (struct my_io *)w_;
734 ... 784 ...
735 } 785 }
736 786
737</pre> 787</pre>
738<p>More interesting and less C-conformant ways of catsing your callback type 788<p>More interesting and less C-conformant ways of casting your callback type
739have been omitted....</p> 789instead have been omitted.</p>
790<p>Another common scenario is having some data structure with multiple
791watchers:</p>
792<pre> struct my_biggy
793 {
794 int some_data;
795 ev_timer t1;
796 ev_timer t2;
797 }
740 798
799</pre>
800<p>In this case getting the pointer to <code>my_biggy</code> is a bit more complicated,
801you need to use <code>offsetof</code>:</p>
802<pre> #include &lt;stddef.h&gt;
741 803
804 static void
805 t1_cb (EV_P_ struct ev_timer *w, int revents)
806 {
807 struct my_biggy big = (struct my_biggy *
808 (((char *)w) - offsetof (struct my_biggy, t1));
809 }
742 810
811 static void
812 t2_cb (EV_P_ struct ev_timer *w, int revents)
813 {
814 struct my_biggy big = (struct my_biggy *
815 (((char *)w) - offsetof (struct my_biggy, t2));
816 }
743 817
744 818
819
820
821</pre>
822
745</div> 823</div>
746<h1 id="WATCHER_TYPES">WATCHER TYPES</h1><p><a href="#TOP" class="toplink">Top</a></p> 824<h1 id="WATCHER_TYPES">WATCHER TYPES</h1>
747<div id="WATCHER_TYPES_CONTENT"> 825<div id="WATCHER_TYPES_CONTENT">
748<p>This section describes each watcher in detail, but will not repeat 826<p>This section describes each watcher in detail, but will not repeat
749information given in the last section. Any initialisation/set macros, 827information given in the last section. Any initialisation/set macros,
750functions and members specific to the watcher type are explained.</p> 828functions and members specific to the watcher type are explained.</p>
751<p>Members are additionally marked with either <i>[read-only]</i>, meaning that, 829<p>Members are additionally marked with either <i>[read-only]</i>, meaning that,
… …
811 <dt>int events [read-only]</dt> 889 <dt>int events [read-only]</dt>
812 <dd> 890 <dd>
813 <p>The events being watched.</p> 891 <p>The events being watched.</p>
814 </dd> 892 </dd>
815</dl> 893</dl>
816<p>Example: call <code>stdin_readable_cb</code> when STDIN_FILENO has become, well 894<p>Example: Call <code>stdin_readable_cb</code> when STDIN_FILENO has become, well
817readable, but only once. Since it is likely line-buffered, you could 895readable, but only once. Since it is likely line-buffered, you could
818attempt to read a whole line in the callback:</p> 896attempt to read a whole line in the callback.</p>
819<pre> static void 897<pre> static void
820 stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents) 898 stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents)
821 { 899 {
822 ev_io_stop (loop, w); 900 ev_io_stop (loop, w);
823 .. read from stdin here (or from w-&gt;fd) and haqndle any I/O errors 901 .. read from stdin here (or from w-&gt;fd) and haqndle any I/O errors
… …
906 <p>The current <code>repeat</code> value. Will be used each time the watcher times out 984 <p>The current <code>repeat</code> value. Will be used each time the watcher times out
907or <code>ev_timer_again</code> is called and determines the next timeout (if any), 985or <code>ev_timer_again</code> is called and determines the next timeout (if any),
908which is also when any modifications are taken into account.</p> 986which is also when any modifications are taken into account.</p>
909 </dd> 987 </dd>
910</dl> 988</dl>
911<p>Example: create a timer that fires after 60 seconds.</p> 989<p>Example: Create a timer that fires after 60 seconds.</p>
912<pre> static void 990<pre> static void
913 one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) 991 one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents)
914 { 992 {
915 .. one minute over, w is actually stopped right here 993 .. one minute over, w is actually stopped right here
916 } 994 }
… …
918 struct ev_timer mytimer; 996 struct ev_timer mytimer;
919 ev_timer_init (&amp;mytimer, one_minute_cb, 60., 0.); 997 ev_timer_init (&amp;mytimer, one_minute_cb, 60., 0.);
920 ev_timer_start (loop, &amp;mytimer); 998 ev_timer_start (loop, &amp;mytimer);
921 999
922</pre> 1000</pre>
923<p>Example: create a timeout timer that times out after 10 seconds of 1001<p>Example: Create a timeout timer that times out after 10 seconds of
924inactivity.</p> 1002inactivity.</p>
925<pre> static void 1003<pre> static void
926 timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents) 1004 timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents)
927 { 1005 {
928 .. ten seconds without any activity 1006 .. ten seconds without any activity
… …
1044 <p>The current reschedule callback, or <code>0</code>, if this functionality is 1122 <p>The current reschedule callback, or <code>0</code>, if this functionality is
1045switched off. Can be changed any time, but changes only take effect when 1123switched off. Can be changed any time, but changes only take effect when
1046the periodic timer fires or <code>ev_periodic_again</code> is being called.</p> 1124the periodic timer fires or <code>ev_periodic_again</code> is being called.</p>
1047 </dd> 1125 </dd>
1048</dl> 1126</dl>
1049<p>Example: call a callback every hour, or, more precisely, whenever the 1127<p>Example: Call a callback every hour, or, more precisely, whenever the
1050system clock is divisible by 3600. The callback invocation times have 1128system clock is divisible by 3600. The callback invocation times have
1051potentially a lot of jittering, but good long-term stability.</p> 1129potentially a lot of jittering, but good long-term stability.</p>
1052<pre> static void 1130<pre> static void
1053 clock_cb (struct ev_loop *loop, struct ev_io *w, int revents) 1131 clock_cb (struct ev_loop *loop, struct ev_io *w, int revents)
1054 { 1132 {
… …
1058 struct ev_periodic hourly_tick; 1136 struct ev_periodic hourly_tick;
1059 ev_periodic_init (&amp;hourly_tick, clock_cb, 0., 3600., 0); 1137 ev_periodic_init (&amp;hourly_tick, clock_cb, 0., 3600., 0);
1060 ev_periodic_start (loop, &amp;hourly_tick); 1138 ev_periodic_start (loop, &amp;hourly_tick);
1061 1139
1062</pre> 1140</pre>
1063<p>Example: the same as above, but use a reschedule callback to do it:</p> 1141<p>Example: The same as above, but use a reschedule callback to do it:</p>
1064<pre> #include &lt;math.h&gt; 1142<pre> #include &lt;math.h&gt;
1065 1143
1066 static ev_tstamp 1144 static ev_tstamp
1067 my_scheduler_cb (struct ev_periodic *w, ev_tstamp now) 1145 my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)
1068 { 1146 {
… …
1070 } 1148 }
1071 1149
1072 ev_periodic_init (&amp;hourly_tick, clock_cb, 0., 0., my_scheduler_cb); 1150 ev_periodic_init (&amp;hourly_tick, clock_cb, 0., 0., my_scheduler_cb);
1073 1151
1074</pre> 1152</pre>
1075<p>Example: call a callback every hour, starting now:</p> 1153<p>Example: Call a callback every hour, starting now:</p>
1076<pre> struct ev_periodic hourly_tick; 1154<pre> struct ev_periodic hourly_tick;
1077 ev_periodic_init (&amp;hourly_tick, clock_cb, 1155 ev_periodic_init (&amp;hourly_tick, clock_cb,
1078 fmod (ev_now (loop), 3600.), 3600., 0); 1156 fmod (ev_now (loop), 3600.), 3600., 0);
1079 ev_periodic_start (loop, &amp;hourly_tick); 1157 ev_periodic_start (loop, &amp;hourly_tick);
1080 1158
… …
1141 <dd> 1219 <dd>
1142 <p>The process exit/trace status caused by <code>rpid</code> (see your systems 1220 <p>The process exit/trace status caused by <code>rpid</code> (see your systems
1143<code>waitpid</code> and <code>sys/wait.h</code> documentation for details).</p> 1221<code>waitpid</code> and <code>sys/wait.h</code> documentation for details).</p>
1144 </dd> 1222 </dd>
1145</dl> 1223</dl>
1146<p>Example: try to exit cleanly on SIGINT and SIGTERM.</p> 1224<p>Example: Try to exit cleanly on SIGINT and SIGTERM.</p>
1147<pre> static void 1225<pre> static void
1148 sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) 1226 sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents)
1149 { 1227 {
1150 ev_unloop (loop, EVUNLOOP_ALL); 1228 ev_unloop (loop, EVUNLOOP_ALL);
1151 } 1229 }
… …
1169not exist&quot; is a status change like any other. The condition &quot;path does 1247not exist&quot; is a status change like any other. The condition &quot;path does
1170not exist&quot; is signified by the <code>st_nlink</code> field being zero (which is 1248not exist&quot; is signified by the <code>st_nlink</code> field being zero (which is
1171otherwise always forced to be at least one) and all the other fields of 1249otherwise always forced to be at least one) and all the other fields of
1172the stat buffer having unspecified contents.</p> 1250the stat buffer having unspecified contents.</p>
1173<p>Since there is no standard to do this, the portable implementation simply 1251<p>Since there is no standard to do this, the portable implementation simply
1174calls <code>stat (2)</code> regulalry on the path to see if it changed somehow. You 1252calls <code>stat (2)</code> regularly on the path to see if it changed somehow. You
1175can specify a recommended polling interval for this case. If you specify 1253can specify a recommended polling interval for this case. If you specify
1176a polling interval of <code>0</code> (highly recommended!) then a <i>suitable, 1254a polling interval of <code>0</code> (highly recommended!) then a <i>suitable,
1177unspecified default</i> value will be used (which you can expect to be around 1255unspecified default</i> value will be used (which you can expect to be around
1178five seconds, although this might change dynamically). Libev will also 1256five seconds, although this might change dynamically). Libev will also
1179impose a minimum interval which is currently around <code>0.1</code>, but thats 1257impose a minimum interval which is currently around <code>0.1</code>, but thats
1180usually overkill.</p> 1258usually overkill.</p>
1181<p>This watcher type is not meant for massive numbers of stat watchers, 1259<p>This watcher type is not meant for massive numbers of stat watchers,
1182as even with OS-supported change notifications, this can be 1260as even with OS-supported change notifications, this can be
1183resource-intensive.</p> 1261resource-intensive.</p>
1184<p>At the time of this writing, no specific OS backends are implemented, but 1262<p>At the time of this writing, only the Linux inotify interface is
1185if demand increases, at least a kqueue and inotify backend will be added.</p> 1263implemented (implementing kqueue support is left as an exercise for the
1264reader). Inotify will be used to give hints only and should not change the
1265semantics of <code>ev_stat</code> watchers, which means that libev sometimes needs
1266to fall back to regular polling again even with inotify, but changes are
1267usually detected immediately, and if the file exists there will be no
1268polling.</p>
1186<dl> 1269<dl>
1187 <dt>ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)</dt> 1270 <dt>ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)</dt>
1188 <dt>ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)</dt> 1271 <dt>ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)</dt>
1189 <dd> 1272 <dd>
1190 <p>Configures the watcher to wait for status changes of the given 1273 <p>Configures the watcher to wait for status changes of the given
… …
1274 <p>Initialises and configures the idle watcher - it has no parameters of any 1357 <p>Initialises and configures the idle watcher - it has no parameters of any
1275kind. There is a <code>ev_idle_set</code> macro, but using it is utterly pointless, 1358kind. There is a <code>ev_idle_set</code> macro, but using it is utterly pointless,
1276believe me.</p> 1359believe me.</p>
1277 </dd> 1360 </dd>
1278</dl> 1361</dl>
1279<p>Example: dynamically allocate an <code>ev_idle</code>, start it, and in the 1362<p>Example: Dynamically allocate an <code>ev_idle</code> watcher, start it, and in the
1280callback, free it. Alos, use no error checking, as usual.</p> 1363callback, free it. Also, use no error checking, as usual.</p>
1281<pre> static void 1364<pre> static void
1282 idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents) 1365 idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents)
1283 { 1366 {
1284 free (w); 1367 free (w);
1285 // now do something you wanted to do when the program has 1368 // now do something you wanted to do when the program has
… …
1510 1593
1511 1594
1512 1595
1513 1596
1514</div> 1597</div>
1515<h1 id="OTHER_FUNCTIONS">OTHER FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p> 1598<h1 id="OTHER_FUNCTIONS">OTHER FUNCTIONS</h1>
1516<div id="OTHER_FUNCTIONS_CONTENT"> 1599<div id="OTHER_FUNCTIONS_CONTENT">
1517<p>There are some other functions of possible interest. Described. Here. Now.</p> 1600<p>There are some other functions of possible interest. Described. Here. Now.</p>
1518<dl> 1601<dl>
1519 <dt>ev_once (loop, int fd, int events, ev_tstamp timeout, callback)</dt> 1602 <dt>ev_once (loop, int fd, int events, ev_tstamp timeout, callback)</dt>
1520 <dd> 1603 <dd>
… …
1567 1650
1568 1651
1569 1652
1570 1653
1571</div> 1654</div>
1572<h1 id="LIBEVENT_EMULATION">LIBEVENT EMULATION</h1><p><a href="#TOP" class="toplink">Top</a></p> 1655<h1 id="LIBEVENT_EMULATION">LIBEVENT EMULATION</h1>
1573<div id="LIBEVENT_EMULATION_CONTENT"> 1656<div id="LIBEVENT_EMULATION_CONTENT">
1574<p>Libev offers a compatibility emulation layer for libevent. It cannot 1657<p>Libev offers a compatibility emulation layer for libevent. It cannot
1575emulate the internals of libevent, so here are some usage hints:</p> 1658emulate the internals of libevent, so here are some usage hints:</p>
1576<dl> 1659<dl>
1577 <dt>* Use it by including &lt;event.h&gt;, as usual.</dt> 1660 <dt>* Use it by including &lt;event.h&gt;, as usual.</dt>
… …
1587 <dt>* The libev emulation is <i>not</i> ABI compatible to libevent, you need 1670 <dt>* The libev emulation is <i>not</i> ABI compatible to libevent, you need
1588to use the libev header file and library.</dt> 1671to use the libev header file and library.</dt>
1589</dl> 1672</dl>
1590 1673
1591</div> 1674</div>
1592<h1 id="C_SUPPORT">C++ SUPPORT</h1><p><a href="#TOP" class="toplink">Top</a></p> 1675<h1 id="C_SUPPORT">C++ SUPPORT</h1>
1593<div id="C_SUPPORT_CONTENT"> 1676<div id="C_SUPPORT_CONTENT">
1594<p>Libev comes with some simplistic wrapper classes for C++ that mainly allow 1677<p>Libev comes with some simplistic wrapper classes for C++ that mainly allow
1595you to use some convinience methods to start/stop watchers and also change 1678you to use some convinience methods to start/stop watchers and also change
1596the callback model to a model using method callbacks on objects.</p> 1679the callback model to a model using method callbacks on objects.</p>
1597<p>To use it,</p> 1680<p>To use it,</p>
… …
1692 1775
1693 1776
1694</pre> 1777</pre>
1695 1778
1696</div> 1779</div>
1697<h1 id="MACRO_MAGIC">MACRO MAGIC</h1><p><a href="#TOP" class="toplink">Top</a></p> 1780<h1 id="MACRO_MAGIC">MACRO MAGIC</h1>
1698<div id="MACRO_MAGIC_CONTENT"> 1781<div id="MACRO_MAGIC_CONTENT">
1699<p>Libev can be compiled with a variety of options, the most fundemantal is 1782<p>Libev can be compiled with a variety of options, the most fundemantal is
1700<code>EV_MULTIPLICITY</code>. This option determines wether (most) functions and 1783<code>EV_MULTIPLICITY</code>. This option determines wether (most) functions and
1701callbacks have an initial <code>struct ev_loop *</code> argument.</p> 1784callbacks have an initial <code>struct ev_loop *</code> argument.</p>
1702<p>To make it easier to write programs that cope with either variant, the 1785<p>To make it easier to write programs that cope with either variant, the
… …
1753 1836
1754 1837
1755</pre> 1838</pre>
1756 1839
1757</div> 1840</div>
1758<h1 id="EMBEDDING">EMBEDDING</h1><p><a href="#TOP" class="toplink">Top</a></p> 1841<h1 id="EMBEDDING">EMBEDDING</h1>
1759<div id="EMBEDDING_CONTENT"> 1842<div id="EMBEDDING_CONTENT">
1760<p>Libev can (and often is) directly embedded into host 1843<p>Libev can (and often is) directly embedded into host
1761applications. Examples of applications that embed it include the Deliantra 1844applications. Examples of applications that embed it include the Deliantra
1762Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe) 1845Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe)
1763and rxvt-unicode.</p> 1846and rxvt-unicode.</p>
… …
1937 </dd> 2020 </dd>
1938 <dt>EV_USE_DEVPOLL</dt> 2021 <dt>EV_USE_DEVPOLL</dt>
1939 <dd> 2022 <dd>
1940 <p>reserved for future expansion, works like the USE symbols above.</p> 2023 <p>reserved for future expansion, works like the USE symbols above.</p>
1941 </dd> 2024 </dd>
2025 <dt>EV_USE_INOTIFY</dt>
2026 <dd>
2027 <p>If defined to be <code>1</code>, libev will compile in support for the Linux inotify
2028interface to speed up <code>ev_stat</code> watchers. Its actual availability will
2029be detected at runtime.</p>
2030 </dd>
1942 <dt>EV_H</dt> 2031 <dt>EV_H</dt>
1943 <dd> 2032 <dd>
1944 <p>The name of the <cite>ev.h</cite> header file used to include it. The default if 2033 <p>The name of the <cite>ev.h</cite> header file used to include it. The default if
1945undefined is <code>&lt;ev.h&gt;</code> in <cite>event.h</cite> and <code>&quot;ev.h&quot;</code> in <cite>ev.c</cite>. This 2034undefined is <code>&lt;ev.h&gt;</code> in <cite>event.h</cite> and <code>&quot;ev.h&quot;</code> in <cite>ev.c</cite>. This
1946can be used to virtually rename the <cite>ev.h</cite> header file in case of conflicts.</p> 2035can be used to virtually rename the <cite>ev.h</cite> header file in case of conflicts.</p>
… …
2001 <dt>EV_PID_HASHSIZE</dt> 2090 <dt>EV_PID_HASHSIZE</dt>
2002 <dd> 2091 <dd>
2003 <p><code>ev_child</code> watchers use a small hash table to distribute workload by 2092 <p><code>ev_child</code> watchers use a small hash table to distribute workload by
2004pid. The default size is <code>16</code> (or <code>1</code> with <code>EV_MINIMAL</code>), usually more 2093pid. The default size is <code>16</code> (or <code>1</code> with <code>EV_MINIMAL</code>), usually more
2005than enough. If you need to manage thousands of children you might want to 2094than enough. If you need to manage thousands of children you might want to
2006increase this value.</p> 2095increase this value (<i>must</i> be a power of two).</p>
2096 </dd>
2097 <dt>EV_INOTIFY_HASHSIZE</dt>
2098 <dd>
2099 <p><code>ev_staz</code> watchers use a small hash table to distribute workload by
2100inotify watch id. The default size is <code>16</code> (or <code>1</code> with <code>EV_MINIMAL</code>),
2101usually more than enough. If you need to manage thousands of <code>ev_stat</code>
2102watchers you might want to increase this value (<i>must</i> be a power of
2103two).</p>
2007 </dd> 2104 </dd>
2008 <dt>EV_COMMON</dt> 2105 <dt>EV_COMMON</dt>
2009 <dd> 2106 <dd>
2010 <p>By default, all watchers have a <code>void *data</code> member. By redefining 2107 <p>By default, all watchers have a <code>void *data</code> member. By redefining
2011this macro to a something else you can include more and other types of 2108this macro to a something else you can include more and other types of
… …
2057 2154
2058 2155
2059</pre> 2156</pre>
2060 2157
2061</div> 2158</div>
2062<h1 id="COMPLEXITIES">COMPLEXITIES</h1><p><a href="#TOP" class="toplink">Top</a></p> 2159<h1 id="COMPLEXITIES">COMPLEXITIES</h1>
2063<div id="COMPLEXITIES_CONTENT"> 2160<div id="COMPLEXITIES_CONTENT">
2064 <p>In this section the complexities of (many of) the algorithms used inside 2161 <p>In this section the complexities of (many of) the algorithms used inside
2065libev will be explained. For complexity discussions about backends see the 2162libev will be explained. For complexity discussions about backends see the
2066documentation for <code>ev_default_init</code>.</p> 2163documentation for <code>ev_default_init</code>.</p>
2067 <p> 2164 <p>
2068 <dl> 2165 <dl>
2069 <dt>Starting and stopping timer/periodic watchers: O(log skipped_other_timers)</dt> 2166 <dt>Starting and stopping timer/periodic watchers: O(log skipped_other_timers)</dt>
2070 <dt>Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)</dt> 2167 <dt>Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)</dt>
2071 <dt>Starting io/check/prepare/idle/signal/child watchers: O(1)</dt> 2168 <dt>Starting io/check/prepare/idle/signal/child watchers: O(1)</dt>
2072 <dt>Stopping check/prepare/idle watchers: O(1)</dt> 2169 <dt>Stopping check/prepare/idle watchers: O(1)</dt>
2073 <dt>Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % 16))</dt> 2170 <dt>Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))</dt>
2074 <dt>Finding the next timer per loop iteration: O(1)</dt> 2171 <dt>Finding the next timer per loop iteration: O(1)</dt>
2075 <dt>Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)</dt> 2172 <dt>Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)</dt>
2076 <dt>Activating one watcher: O(1)</dt> 2173 <dt>Activating one watcher: O(1)</dt>
2077 </dl> 2174 </dl>
2078 </p> 2175 </p>
… …
2080 2177
2081 2178
2082 2179
2083 2180
2084</div> 2181</div>
2085<h1 id="AUTHOR">AUTHOR</h1><p><a href="#TOP" class="toplink">Top</a></p> 2182<h1 id="AUTHOR">AUTHOR</h1>
2086<div id="AUTHOR_CONTENT"> 2183<div id="AUTHOR_CONTENT">
2087 <p>Marc Lehmann &lt;libev@schmorp.de&gt;.</p> 2184 <p>Marc Lehmann &lt;libev@schmorp.de&gt;.</p>
2088 2185
2089</div> 2186</div>
2090</div></body> 2187</div></body>

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