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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 21:14:27 2007" /> 9 <meta name="created" content="Wed Nov 28 19:29:25 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> /* this is the only header you need */
72 #include &lt;ev.h&gt; 72<pre> #include &lt;ev.h&gt;
73 73
74 /* what follows is a fully working example program */ 74</pre>
75
76</div>
77<h1 id="EXAMPLE_PROGRAM">EXAMPLE PROGRAM</h1>
78<div id="EXAMPLE_PROGRAM_CONTENT">
79<pre> #include &lt;ev.h&gt;
80
75 ev_io stdin_watcher; 81 ev_io stdin_watcher;
76 ev_timer timeout_watcher; 82 ev_timer timeout_watcher;
77 83
78 /* called when data readable on stdin */ 84 /* called when data readable on stdin */
79 static void 85 static void
… …
111 } 117 }
112 118
113</pre> 119</pre>
114 120
115</div> 121</div>
116<h1 id="DESCRIPTION">DESCRIPTION</h1><p><a href="#TOP" class="toplink">Top</a></p> 122<h1 id="DESCRIPTION">DESCRIPTION</h1>
117<div id="DESCRIPTION_CONTENT"> 123<div id="DESCRIPTION_CONTENT">
118<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
119file descriptor being readable or a timeout occuring), and it will manage 125file descriptor being readable or a timeout occuring), and it will manage
120these event sources and provide your program with events.</p> 126these event sources and provide your program with events.</p>
121<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
… …
125watchers</i>, which are relatively small C structures you initialise with the 131watchers</i>, which are relatively small C structures you initialise with the
126details 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
127watcher.</p> 133watcher.</p>
128 134
129</div> 135</div>
130<h1 id="FEATURES">FEATURES</h1><p><a href="#TOP" class="toplink">Top</a></p> 136<h1 id="FEATURES">FEATURES</h1>
131<div id="FEATURES_CONTENT"> 137<div id="FEATURES_CONTENT">
132<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
133kqueue mechanisms for file descriptor events, relative timers, absolute 139BSD-specific <code>kqueue</code> and the Solaris-specific event port mechanisms
134timers with customised rescheduling, signal events, process status change 140for file descriptor events (<code>ev_io</code>), the Linux <code>inotify</code> interface
135events (related to SIGCHLD), and event watchers dealing with the event 141(for <code>ev_stat</code>), relative timers (<code>ev_timer</code>), absolute timers
136loop mechanism itself (idle, prepare and check watchers). It also is quite 142with customised rescheduling (<code>ev_periodic</code>), synchronous signals
143(<code>ev_signal</code>), process status change events (<code>ev_child</code>), and event
144watchers dealing with the event loop mechanism itself (<code>ev_idle</code>,
145<code>ev_embed</code>, <code>ev_prepare</code> and <code>ev_check</code> watchers) as well as
146file watchers (<code>ev_stat</code>) and even limited support for fork events
147(<code>ev_fork</code>).</p>
148<p>It also is quite fast (see this
137fast (see this <a href="http://libev.schmorp.de/bench.html">benchmark</a> comparing 149<a href="http://libev.schmorp.de/bench.html">benchmark</a> comparing it to libevent
138it to libevent for example).</p> 150for example).</p>
139 151
140</div> 152</div>
141<h1 id="CONVENTIONS">CONVENTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p> 153<h1 id="CONVENTIONS">CONVENTIONS</h1>
142<div id="CONVENTIONS_CONTENT"> 154<div id="CONVENTIONS_CONTENT">
143<p>Libev is very configurable. In this manual the default configuration 155<p>Libev is very configurable. In this manual the default configuration will
144will be described, which supports multiple event loops. For more info 156be described, which supports multiple event loops. For more info about
145about various configuration options please have a look at the file 157various configuration options please have a look at <strong>EMBED</strong> section in
146<cite>README.embed</cite> in the libev distribution. If libev was configured without 158this manual. If libev was configured without support for multiple event
147support for multiple event loops, then all functions taking an initial 159loops, then all functions taking an initial argument of name <code>loop</code>
148argument of name <code>loop</code> (which is always of type <code>struct ev_loop *</code>) 160(which is always of type <code>struct ev_loop *</code>) will not have this argument.</p>
149will not have this argument.</p>
150 161
151</div> 162</div>
152<h1 id="TIME_REPRESENTATION">TIME REPRESENTATION</h1><p><a href="#TOP" class="toplink">Top</a></p> 163<h1 id="TIME_REPRESENTATION">TIME REPRESENTATION</h1>
153<div id="TIME_REPRESENTATION_CONTENT"> 164<div id="TIME_REPRESENTATION_CONTENT">
154<p>Libev represents time as a single floating point number, representing the 165<p>Libev represents time as a single floating point number, representing the
155(fractional) number of seconds since the (POSIX) epoch (somewhere near 166(fractional) number of seconds since the (POSIX) epoch (somewhere near
156the beginning of 1970, details are complicated, don't ask). This type is 167the beginning of 1970, details are complicated, don't ask). This type is
157called <code>ev_tstamp</code>, which is what you should use too. It usually aliases 168called <code>ev_tstamp</code>, which is what you should use too. It usually aliases
158to the <code>double</code> type in C, and when you need to do any calculations on 169to the <code>double</code> type in C, and when you need to do any calculations on
159it, you should treat it as such.</p> 170it, you should treat it as such.</p>
160 171
161</div> 172</div>
162<h1 id="GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p> 173<h1 id="GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</h1>
163<div id="GLOBAL_FUNCTIONS_CONTENT"> 174<div id="GLOBAL_FUNCTIONS_CONTENT">
164<p>These functions can be called anytime, even before initialising the 175<p>These functions can be called anytime, even before initialising the
165library in any way.</p> 176library in any way.</p>
166<dl> 177<dl>
167 <dt>ev_tstamp ev_time ()</dt> 178 <dt>ev_tstamp ev_time ()</dt>
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180version of the library your program was compiled against.</p> 191version of the library your program was compiled against.</p>
181 <p>Usually, it's a good idea to terminate if the major versions mismatch, 192 <p>Usually, it's a good idea to terminate if the major versions mismatch,
182as this indicates an incompatible change. Minor versions are usually 193as this indicates an incompatible change. Minor versions are usually
183compatible to older versions, so a larger minor version alone is usually 194compatible to older versions, so a larger minor version alone is usually
184not a problem.</p> 195not a problem.</p>
185 <p>Example: make sure we haven't accidentally been linked against the wrong 196 <p>Example: Make sure we haven't accidentally been linked against the wrong
186version:</p> 197version.</p>
187<pre> assert ((&quot;libev version mismatch&quot;, 198<pre> assert ((&quot;libev version mismatch&quot;,
188 ev_version_major () == EV_VERSION_MAJOR 199 ev_version_major () == EV_VERSION_MAJOR
189 &amp;&amp; ev_version_minor () &gt;= EV_VERSION_MINOR)); 200 &amp;&amp; ev_version_minor () &gt;= EV_VERSION_MINOR));
190 201
191</pre> 202</pre>
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219might be supported on the current system, you would need to look at 230might be supported on the current system, you would need to look at
220<code>ev_embeddable_backends () &amp; ev_supported_backends ()</code>, likewise for 231<code>ev_embeddable_backends () &amp; ev_supported_backends ()</code>, likewise for
221recommended ones.</p> 232recommended ones.</p>
222 <p>See the description of <code>ev_embed</code> watchers for more info.</p> 233 <p>See the description of <code>ev_embed</code> watchers for more info.</p>
223 </dd> 234 </dd>
224 <dt>ev_set_allocator (void *(*cb)(void *ptr, size_t size))</dt> 235 <dt>ev_set_allocator (void *(*cb)(void *ptr, long size))</dt>
225 <dd> 236 <dd>
226 <p>Sets the allocation function to use (the prototype and semantics are 237 <p>Sets the allocation function to use (the prototype is similar - the
227identical to the realloc C function). It is used to allocate and free 238semantics is identical - to the realloc C function). It is used to
228memory (no surprises here). If it returns zero when memory needs to be 239allocate and free memory (no surprises here). If it returns zero when
229allocated, the library might abort or take some potentially destructive 240memory needs to be allocated, the library might abort or take some
230action. The default is your system realloc function.</p> 241potentially destructive action. The default is your system realloc
242function.</p>
231 <p>You could override this function in high-availability programs to, say, 243 <p>You could override this function in high-availability programs to, say,
232free some memory if it cannot allocate memory, to use a special allocator, 244free some memory if it cannot allocate memory, to use a special allocator,
233or even to sleep a while and retry until some memory is available.</p> 245or even to sleep a while and retry until some memory is available.</p>
234 <p>Example: replace the libev allocator with one that waits a bit and then 246 <p>Example: Replace the libev allocator with one that waits a bit and then
235retries: better than mine).</p> 247retries).</p>
236<pre> static void * 248<pre> static void *
237 persistent_realloc (void *ptr, size_t size) 249 persistent_realloc (void *ptr, size_t size)
238 { 250 {
239 for (;;) 251 for (;;)
240 { 252 {
… …
259indicating the system call or subsystem causing the problem. If this 271indicating the system call or subsystem causing the problem. If this
260callback is set, then libev will expect it to remedy the sitution, no 272callback is set, then libev will expect it to remedy the sitution, no
261matter what, when it returns. That is, libev will generally retry the 273matter what, when it returns. That is, libev will generally retry the
262requested operation, or, if the condition doesn't go away, do bad stuff 274requested operation, or, if the condition doesn't go away, do bad stuff
263(such as abort).</p> 275(such as abort).</p>
264 <p>Example: do the same thing as libev does internally:</p> 276 <p>Example: This is basically the same thing that libev does internally, too.</p>
265<pre> static void 277<pre> static void
266 fatal_error (const char *msg) 278 fatal_error (const char *msg)
267 { 279 {
268 perror (msg); 280 perror (msg);
269 abort (); 281 abort ();
… …
275</pre> 287</pre>
276 </dd> 288 </dd>
277</dl> 289</dl>
278 290
279</div> 291</div>
280<h1 id="FUNCTIONS_CONTROLLING_THE_EVENT_LOOP">FUNCTIONS CONTROLLING THE EVENT LOOP</h1><p><a href="#TOP" class="toplink">Top</a></p> 292<h1 id="FUNCTIONS_CONTROLLING_THE_EVENT_LOOP">FUNCTIONS CONTROLLING THE EVENT LOOP</h1>
281<div id="FUNCTIONS_CONTROLLING_THE_EVENT_LOOP-2"> 293<div id="FUNCTIONS_CONTROLLING_THE_EVENT_LOOP-2">
282<p>An event loop is described by a <code>struct ev_loop *</code>. The library knows two 294<p>An event loop is described by a <code>struct ev_loop *</code>. The library knows two
283types of such loops, the <i>default</i> loop, which supports signals and child 295types of such loops, the <i>default</i> loop, which supports signals and child
284events, and dynamically created loops which do not.</p> 296events, and dynamically created loops which do not.</p>
285<p>If you use threads, a common model is to run the default event loop 297<p>If you use threads, a common model is to run the default event loop
… …
405 <dd> 417 <dd>
406 <p>Similar to <code>ev_default_loop</code>, but always creates a new event loop that is 418 <p>Similar to <code>ev_default_loop</code>, but always creates a new event loop that is
407always distinct from the default loop. Unlike the default loop, it cannot 419always distinct from the default loop. Unlike the default loop, it cannot
408handle signal and child watchers, and attempts to do so will be greeted by 420handle signal and child watchers, and attempts to do so will be greeted by
409undefined behaviour (or a failed assertion if assertions are enabled).</p> 421undefined behaviour (or a failed assertion if assertions are enabled).</p>
410 <p>Example: try to create a event loop that uses epoll and nothing else.</p> 422 <p>Example: Try to create a event loop that uses epoll and nothing else.</p>
411<pre> struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); 423<pre> struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);
412 if (!epoller) 424 if (!epoller)
413 fatal (&quot;no epoll found here, maybe it hides under your chair&quot;); 425 fatal (&quot;no epoll found here, maybe it hides under your chair&quot;);
414 426
415</pre> 427</pre>
… …
508 be handled here by queueing them when their watcher gets executed. 520 be handled here by queueing them when their watcher gets executed.
509 - If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK 521 - If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK
510 were used, return, otherwise continue with step *. 522 were used, return, otherwise continue with step *.
511 523
512</pre> 524</pre>
513 <p>Example: queue some jobs and then loop until no events are outsanding 525 <p>Example: Queue some jobs and then loop until no events are outsanding
514anymore.</p> 526anymore.</p>
515<pre> ... queue jobs here, make sure they register event watchers as long 527<pre> ... queue jobs here, make sure they register event watchers as long
516 ... as they still have work to do (even an idle watcher will do..) 528 ... as they still have work to do (even an idle watcher will do..)
517 ev_loop (my_loop, 0); 529 ev_loop (my_loop, 0);
518 ... jobs done. yeah! 530 ... jobs done. yeah!
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537example, libev itself uses this for its internal signal pipe: It is not 549example, libev itself uses this for its internal signal pipe: It is not
538visible to the libev user and should not keep <code>ev_loop</code> from exiting if 550visible to the libev user and should not keep <code>ev_loop</code> from exiting if
539no event watchers registered by it are active. It is also an excellent 551no event watchers registered by it are active. It is also an excellent
540way to do this for generic recurring timers or from within third-party 552way to do this for generic recurring timers or from within third-party
541libraries. Just remember to <i>unref after start</i> and <i>ref before stop</i>.</p> 553libraries. Just remember to <i>unref after start</i> and <i>ref before stop</i>.</p>
542 <p>Example: create a signal watcher, but keep it from keeping <code>ev_loop</code> 554 <p>Example: Create a signal watcher, but keep it from keeping <code>ev_loop</code>
543running when nothing else is active.</p> 555running when nothing else is active.</p>
544<pre> struct dv_signal exitsig; 556<pre> struct ev_signal exitsig;
545 ev_signal_init (&amp;exitsig, sig_cb, SIGINT); 557 ev_signal_init (&amp;exitsig, sig_cb, SIGINT);
546 ev_signal_start (myloop, &amp;exitsig); 558 ev_signal_start (loop, &amp;exitsig);
547 evf_unref (myloop); 559 evf_unref (loop);
548 560
549</pre> 561</pre>
550 <p>Example: for some weird reason, unregister the above signal handler again.</p> 562 <p>Example: For some weird reason, unregister the above signal handler again.</p>
551<pre> ev_ref (myloop); 563<pre> ev_ref (loop);
552 ev_signal_stop (myloop, &amp;exitsig); 564 ev_signal_stop (loop, &amp;exitsig);
553 565
554</pre> 566</pre>
555 </dd> 567 </dd>
556</dl> 568</dl>
557 569
558 570
559 571
560 572
561 573
562</div> 574</div>
563<h1 id="ANATOMY_OF_A_WATCHER">ANATOMY OF A WATCHER</h1><p><a href="#TOP" class="toplink">Top</a></p> 575<h1 id="ANATOMY_OF_A_WATCHER">ANATOMY OF A WATCHER</h1>
564<div id="ANATOMY_OF_A_WATCHER_CONTENT"> 576<div id="ANATOMY_OF_A_WATCHER_CONTENT">
565<p>A watcher is a structure that you create and register to record your 577<p>A watcher is a structure that you create and register to record your
566interest in some event. For instance, if you want to wait for STDIN to 578interest in some event. For instance, if you want to wait for STDIN to
567become readable, you would create an <code>ev_io</code> watcher for that:</p> 579become readable, you would create an <code>ev_io</code> watcher for that:</p>
568<pre> static void my_cb (struct ev_loop *loop, struct ev_io *w, int revents) 580<pre> static void my_cb (struct ev_loop *loop, struct ev_io *w, int revents)
… …
731events but its callback has not yet been invoked). As long as a watcher 743events but its callback has not yet been invoked). As long as a watcher
732is pending (but not active) you must not call an init function on it (but 744is pending (but not active) you must not call an init function on it (but
733<code>ev_TYPE_set</code> is safe) and you must make sure the watcher is available to 745<code>ev_TYPE_set</code> is safe) and you must make sure the watcher is available to
734libev (e.g. you cnanot <code>free ()</code> it).</p> 746libev (e.g. you cnanot <code>free ()</code> it).</p>
735 </dd> 747 </dd>
736 <dt>callback = ev_cb (ev_TYPE *watcher)</dt> 748 <dt>callback ev_cb (ev_TYPE *watcher)</dt>
737 <dd> 749 <dd>
738 <p>Returns the callback currently set on the watcher.</p> 750 <p>Returns the callback currently set on the watcher.</p>
739 </dd> 751 </dd>
740 <dt>ev_cb_set (ev_TYPE *watcher, callback)</dt> 752 <dt>ev_cb_set (ev_TYPE *watcher, callback)</dt>
741 <dd> 753 <dd>
… …
773 struct my_io *w = (struct my_io *)w_; 785 struct my_io *w = (struct my_io *)w_;
774 ... 786 ...
775 } 787 }
776 788
777</pre> 789</pre>
778<p>More interesting and less C-conformant ways of catsing your callback type 790<p>More interesting and less C-conformant ways of casting your callback type
779have been omitted....</p> 791instead have been omitted.</p>
792<p>Another common scenario is having some data structure with multiple
793watchers:</p>
794<pre> struct my_biggy
795 {
796 int some_data;
797 ev_timer t1;
798 ev_timer t2;
799 }
780 800
801</pre>
802<p>In this case getting the pointer to <code>my_biggy</code> is a bit more complicated,
803you need to use <code>offsetof</code>:</p>
804<pre> #include &lt;stddef.h&gt;
781 805
806 static void
807 t1_cb (EV_P_ struct ev_timer *w, int revents)
808 {
809 struct my_biggy big = (struct my_biggy *
810 (((char *)w) - offsetof (struct my_biggy, t1));
811 }
782 812
813 static void
814 t2_cb (EV_P_ struct ev_timer *w, int revents)
815 {
816 struct my_biggy big = (struct my_biggy *
817 (((char *)w) - offsetof (struct my_biggy, t2));
818 }
783 819
784 820
821
822
823</pre>
824
785</div> 825</div>
786<h1 id="WATCHER_TYPES">WATCHER TYPES</h1><p><a href="#TOP" class="toplink">Top</a></p> 826<h1 id="WATCHER_TYPES">WATCHER TYPES</h1>
787<div id="WATCHER_TYPES_CONTENT"> 827<div id="WATCHER_TYPES_CONTENT">
788<p>This section describes each watcher in detail, but will not repeat 828<p>This section describes each watcher in detail, but will not repeat
789information given in the last section. Any initialisation/set macros, 829information given in the last section. Any initialisation/set macros,
790functions and members specific to the watcher type are explained.</p> 830functions and members specific to the watcher type are explained.</p>
791<p>Members are additionally marked with either <i>[read-only]</i>, meaning that, 831<p>Members are additionally marked with either <i>[read-only]</i>, meaning that,
… …
851 <dt>int events [read-only]</dt> 891 <dt>int events [read-only]</dt>
852 <dd> 892 <dd>
853 <p>The events being watched.</p> 893 <p>The events being watched.</p>
854 </dd> 894 </dd>
855</dl> 895</dl>
856<p>Example: call <code>stdin_readable_cb</code> when STDIN_FILENO has become, well 896<p>Example: Call <code>stdin_readable_cb</code> when STDIN_FILENO has become, well
857readable, but only once. Since it is likely line-buffered, you could 897readable, but only once. Since it is likely line-buffered, you could
858attempt to read a whole line in the callback:</p> 898attempt to read a whole line in the callback.</p>
859<pre> static void 899<pre> static void
860 stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents) 900 stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents)
861 { 901 {
862 ev_io_stop (loop, w); 902 ev_io_stop (loop, w);
863 .. read from stdin here (or from w-&gt;fd) and haqndle any I/O errors 903 .. read from stdin here (or from w-&gt;fd) and haqndle any I/O errors
… …
946 <p>The current <code>repeat</code> value. Will be used each time the watcher times out 986 <p>The current <code>repeat</code> value. Will be used each time the watcher times out
947or <code>ev_timer_again</code> is called and determines the next timeout (if any), 987or <code>ev_timer_again</code> is called and determines the next timeout (if any),
948which is also when any modifications are taken into account.</p> 988which is also when any modifications are taken into account.</p>
949 </dd> 989 </dd>
950</dl> 990</dl>
951<p>Example: create a timer that fires after 60 seconds.</p> 991<p>Example: Create a timer that fires after 60 seconds.</p>
952<pre> static void 992<pre> static void
953 one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) 993 one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents)
954 { 994 {
955 .. one minute over, w is actually stopped right here 995 .. one minute over, w is actually stopped right here
956 } 996 }
… …
958 struct ev_timer mytimer; 998 struct ev_timer mytimer;
959 ev_timer_init (&amp;mytimer, one_minute_cb, 60., 0.); 999 ev_timer_init (&amp;mytimer, one_minute_cb, 60., 0.);
960 ev_timer_start (loop, &amp;mytimer); 1000 ev_timer_start (loop, &amp;mytimer);
961 1001
962</pre> 1002</pre>
963<p>Example: create a timeout timer that times out after 10 seconds of 1003<p>Example: Create a timeout timer that times out after 10 seconds of
964inactivity.</p> 1004inactivity.</p>
965<pre> static void 1005<pre> static void
966 timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents) 1006 timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents)
967 { 1007 {
968 .. ten seconds without any activity 1008 .. ten seconds without any activity
… …
1084 <p>The current reschedule callback, or <code>0</code>, if this functionality is 1124 <p>The current reschedule callback, or <code>0</code>, if this functionality is
1085switched off. Can be changed any time, but changes only take effect when 1125switched off. Can be changed any time, but changes only take effect when
1086the periodic timer fires or <code>ev_periodic_again</code> is being called.</p> 1126the periodic timer fires or <code>ev_periodic_again</code> is being called.</p>
1087 </dd> 1127 </dd>
1088</dl> 1128</dl>
1089<p>Example: call a callback every hour, or, more precisely, whenever the 1129<p>Example: Call a callback every hour, or, more precisely, whenever the
1090system clock is divisible by 3600. The callback invocation times have 1130system clock is divisible by 3600. The callback invocation times have
1091potentially a lot of jittering, but good long-term stability.</p> 1131potentially a lot of jittering, but good long-term stability.</p>
1092<pre> static void 1132<pre> static void
1093 clock_cb (struct ev_loop *loop, struct ev_io *w, int revents) 1133 clock_cb (struct ev_loop *loop, struct ev_io *w, int revents)
1094 { 1134 {
… …
1098 struct ev_periodic hourly_tick; 1138 struct ev_periodic hourly_tick;
1099 ev_periodic_init (&amp;hourly_tick, clock_cb, 0., 3600., 0); 1139 ev_periodic_init (&amp;hourly_tick, clock_cb, 0., 3600., 0);
1100 ev_periodic_start (loop, &amp;hourly_tick); 1140 ev_periodic_start (loop, &amp;hourly_tick);
1101 1141
1102</pre> 1142</pre>
1103<p>Example: the same as above, but use a reschedule callback to do it:</p> 1143<p>Example: The same as above, but use a reschedule callback to do it:</p>
1104<pre> #include &lt;math.h&gt; 1144<pre> #include &lt;math.h&gt;
1105 1145
1106 static ev_tstamp 1146 static ev_tstamp
1107 my_scheduler_cb (struct ev_periodic *w, ev_tstamp now) 1147 my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)
1108 { 1148 {
… …
1110 } 1150 }
1111 1151
1112 ev_periodic_init (&amp;hourly_tick, clock_cb, 0., 0., my_scheduler_cb); 1152 ev_periodic_init (&amp;hourly_tick, clock_cb, 0., 0., my_scheduler_cb);
1113 1153
1114</pre> 1154</pre>
1115<p>Example: call a callback every hour, starting now:</p> 1155<p>Example: Call a callback every hour, starting now:</p>
1116<pre> struct ev_periodic hourly_tick; 1156<pre> struct ev_periodic hourly_tick;
1117 ev_periodic_init (&amp;hourly_tick, clock_cb, 1157 ev_periodic_init (&amp;hourly_tick, clock_cb,
1118 fmod (ev_now (loop), 3600.), 3600., 0); 1158 fmod (ev_now (loop), 3600.), 3600., 0);
1119 ev_periodic_start (loop, &amp;hourly_tick); 1159 ev_periodic_start (loop, &amp;hourly_tick);
1120 1160
… …
1181 <dd> 1221 <dd>
1182 <p>The process exit/trace status caused by <code>rpid</code> (see your systems 1222 <p>The process exit/trace status caused by <code>rpid</code> (see your systems
1183<code>waitpid</code> and <code>sys/wait.h</code> documentation for details).</p> 1223<code>waitpid</code> and <code>sys/wait.h</code> documentation for details).</p>
1184 </dd> 1224 </dd>
1185</dl> 1225</dl>
1186<p>Example: try to exit cleanly on SIGINT and SIGTERM.</p> 1226<p>Example: Try to exit cleanly on SIGINT and SIGTERM.</p>
1187<pre> static void 1227<pre> static void
1188 sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) 1228 sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents)
1189 { 1229 {
1190 ev_unloop (loop, EVUNLOOP_ALL); 1230 ev_unloop (loop, EVUNLOOP_ALL);
1191 } 1231 }
… …
1208<p>The path does not need to exist: changing from &quot;path exists&quot; to &quot;path does 1248<p>The path does not need to exist: changing from &quot;path exists&quot; to &quot;path does
1209not exist&quot; is a status change like any other. The condition &quot;path does 1249not exist&quot; is a status change like any other. The condition &quot;path does
1210not exist&quot; is signified by the <code>st_nlink</code> field being zero (which is 1250not exist&quot; is signified by the <code>st_nlink</code> field being zero (which is
1211otherwise always forced to be at least one) and all the other fields of 1251otherwise always forced to be at least one) and all the other fields of
1212the stat buffer having unspecified contents.</p> 1252the stat buffer having unspecified contents.</p>
1253<p>The path <i>should</i> be absolute and <i>must not</i> end in a slash. If it is
1254relative and your working directory changes, the behaviour is undefined.</p>
1213<p>Since there is no standard to do this, the portable implementation simply 1255<p>Since there is no standard to do this, the portable implementation simply
1214calls <code>stat (2)</code> regulalry on the path to see if it changed somehow. You 1256calls <code>stat (2)</code> regularly on the path to see if it changed somehow. You
1215can specify a recommended polling interval for this case. If you specify 1257can specify a recommended polling interval for this case. If you specify
1216a polling interval of <code>0</code> (highly recommended!) then a <i>suitable, 1258a polling interval of <code>0</code> (highly recommended!) then a <i>suitable,
1217unspecified default</i> value will be used (which you can expect to be around 1259unspecified default</i> value will be used (which you can expect to be around
1218five seconds, although this might change dynamically). Libev will also 1260five seconds, although this might change dynamically). Libev will also
1219impose a minimum interval which is currently around <code>0.1</code>, but thats 1261impose a minimum interval which is currently around <code>0.1</code>, but thats
1220usually overkill.</p> 1262usually overkill.</p>
1221<p>This watcher type is not meant for massive numbers of stat watchers, 1263<p>This watcher type is not meant for massive numbers of stat watchers,
1222as even with OS-supported change notifications, this can be 1264as even with OS-supported change notifications, this can be
1223resource-intensive.</p> 1265resource-intensive.</p>
1224<p>At the time of this writing, no specific OS backends are implemented, but 1266<p>At the time of this writing, only the Linux inotify interface is
1225if demand increases, at least a kqueue and inotify backend will be added.</p> 1267implemented (implementing kqueue support is left as an exercise for the
1268reader). Inotify will be used to give hints only and should not change the
1269semantics of <code>ev_stat</code> watchers, which means that libev sometimes needs
1270to fall back to regular polling again even with inotify, but changes are
1271usually detected immediately, and if the file exists there will be no
1272polling.</p>
1226<dl> 1273<dl>
1227 <dt>ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)</dt> 1274 <dt>ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)</dt>
1228 <dt>ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)</dt> 1275 <dt>ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)</dt>
1229 <dd> 1276 <dd>
1230 <p>Configures the watcher to wait for status changes of the given 1277 <p>Configures the watcher to wait for status changes of the given
… …
1314 <p>Initialises and configures the idle watcher - it has no parameters of any 1361 <p>Initialises and configures the idle watcher - it has no parameters of any
1315kind. There is a <code>ev_idle_set</code> macro, but using it is utterly pointless, 1362kind. There is a <code>ev_idle_set</code> macro, but using it is utterly pointless,
1316believe me.</p> 1363believe me.</p>
1317 </dd> 1364 </dd>
1318</dl> 1365</dl>
1319<p>Example: dynamically allocate an <code>ev_idle</code>, start it, and in the 1366<p>Example: Dynamically allocate an <code>ev_idle</code> watcher, start it, and in the
1320callback, free it. Alos, use no error checking, as usual.</p> 1367callback, free it. Also, use no error checking, as usual.</p>
1321<pre> static void 1368<pre> static void
1322 idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents) 1369 idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents)
1323 { 1370 {
1324 free (w); 1371 free (w);
1325 // now do something you wanted to do when the program has 1372 // now do something you wanted to do when the program has
… …
1550 1597
1551 1598
1552 1599
1553 1600
1554</div> 1601</div>
1555<h1 id="OTHER_FUNCTIONS">OTHER FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p> 1602<h1 id="OTHER_FUNCTIONS">OTHER FUNCTIONS</h1>
1556<div id="OTHER_FUNCTIONS_CONTENT"> 1603<div id="OTHER_FUNCTIONS_CONTENT">
1557<p>There are some other functions of possible interest. Described. Here. Now.</p> 1604<p>There are some other functions of possible interest. Described. Here. Now.</p>
1558<dl> 1605<dl>
1559 <dt>ev_once (loop, int fd, int events, ev_tstamp timeout, callback)</dt> 1606 <dt>ev_once (loop, int fd, int events, ev_tstamp timeout, callback)</dt>
1560 <dd> 1607 <dd>
… …
1607 1654
1608 1655
1609 1656
1610 1657
1611</div> 1658</div>
1612<h1 id="LIBEVENT_EMULATION">LIBEVENT EMULATION</h1><p><a href="#TOP" class="toplink">Top</a></p> 1659<h1 id="LIBEVENT_EMULATION">LIBEVENT EMULATION</h1>
1613<div id="LIBEVENT_EMULATION_CONTENT"> 1660<div id="LIBEVENT_EMULATION_CONTENT">
1614<p>Libev offers a compatibility emulation layer for libevent. It cannot 1661<p>Libev offers a compatibility emulation layer for libevent. It cannot
1615emulate the internals of libevent, so here are some usage hints:</p> 1662emulate the internals of libevent, so here are some usage hints:</p>
1616<dl> 1663<dl>
1617 <dt>* Use it by including &lt;event.h&gt;, as usual.</dt> 1664 <dt>* Use it by including &lt;event.h&gt;, as usual.</dt>
… …
1627 <dt>* The libev emulation is <i>not</i> ABI compatible to libevent, you need 1674 <dt>* The libev emulation is <i>not</i> ABI compatible to libevent, you need
1628to use the libev header file and library.</dt> 1675to use the libev header file and library.</dt>
1629</dl> 1676</dl>
1630 1677
1631</div> 1678</div>
1632<h1 id="C_SUPPORT">C++ SUPPORT</h1><p><a href="#TOP" class="toplink">Top</a></p> 1679<h1 id="C_SUPPORT">C++ SUPPORT</h1>
1633<div id="C_SUPPORT_CONTENT"> 1680<div id="C_SUPPORT_CONTENT">
1634<p>Libev comes with some simplistic wrapper classes for C++ that mainly allow 1681<p>Libev comes with some simplistic wrapper classes for C++ that mainly allow
1635you to use some convinience methods to start/stop watchers and also change 1682you to use some convinience methods to start/stop watchers and also change
1636the callback model to a model using method callbacks on objects.</p> 1683the callback model to a model using method callbacks on objects.</p>
1637<p>To use it,</p> 1684<p>To use it,</p>
… …
1732 1779
1733 1780
1734</pre> 1781</pre>
1735 1782
1736</div> 1783</div>
1737<h1 id="MACRO_MAGIC">MACRO MAGIC</h1><p><a href="#TOP" class="toplink">Top</a></p> 1784<h1 id="MACRO_MAGIC">MACRO MAGIC</h1>
1738<div id="MACRO_MAGIC_CONTENT"> 1785<div id="MACRO_MAGIC_CONTENT">
1739<p>Libev can be compiled with a variety of options, the most fundemantal is 1786<p>Libev can be compiled with a variety of options, the most fundemantal is
1740<code>EV_MULTIPLICITY</code>. This option determines wether (most) functions and 1787<code>EV_MULTIPLICITY</code>. This option determines wether (most) functions and
1741callbacks have an initial <code>struct ev_loop *</code> argument.</p> 1788callbacks have an initial <code>struct ev_loop *</code> argument.</p>
1742<p>To make it easier to write programs that cope with either variant, the 1789<p>To make it easier to write programs that cope with either variant, the
… …
1793 1840
1794 1841
1795</pre> 1842</pre>
1796 1843
1797</div> 1844</div>
1798<h1 id="EMBEDDING">EMBEDDING</h1><p><a href="#TOP" class="toplink">Top</a></p> 1845<h1 id="EMBEDDING">EMBEDDING</h1>
1799<div id="EMBEDDING_CONTENT"> 1846<div id="EMBEDDING_CONTENT">
1800<p>Libev can (and often is) directly embedded into host 1847<p>Libev can (and often is) directly embedded into host
1801applications. Examples of applications that embed it include the Deliantra 1848applications. Examples of applications that embed it include the Deliantra
1802Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe) 1849Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe)
1803and rxvt-unicode.</p> 1850and rxvt-unicode.</p>
… …
1977 </dd> 2024 </dd>
1978 <dt>EV_USE_DEVPOLL</dt> 2025 <dt>EV_USE_DEVPOLL</dt>
1979 <dd> 2026 <dd>
1980 <p>reserved for future expansion, works like the USE symbols above.</p> 2027 <p>reserved for future expansion, works like the USE symbols above.</p>
1981 </dd> 2028 </dd>
2029 <dt>EV_USE_INOTIFY</dt>
2030 <dd>
2031 <p>If defined to be <code>1</code>, libev will compile in support for the Linux inotify
2032interface to speed up <code>ev_stat</code> watchers. Its actual availability will
2033be detected at runtime.</p>
2034 </dd>
1982 <dt>EV_H</dt> 2035 <dt>EV_H</dt>
1983 <dd> 2036 <dd>
1984 <p>The name of the <cite>ev.h</cite> header file used to include it. The default if 2037 <p>The name of the <cite>ev.h</cite> header file used to include it. The default if
1985undefined 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 2038undefined 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
1986can be used to virtually rename the <cite>ev.h</cite> header file in case of conflicts.</p> 2039can be used to virtually rename the <cite>ev.h</cite> header file in case of conflicts.</p>
… …
2041 <dt>EV_PID_HASHSIZE</dt> 2094 <dt>EV_PID_HASHSIZE</dt>
2042 <dd> 2095 <dd>
2043 <p><code>ev_child</code> watchers use a small hash table to distribute workload by 2096 <p><code>ev_child</code> watchers use a small hash table to distribute workload by
2044pid. The default size is <code>16</code> (or <code>1</code> with <code>EV_MINIMAL</code>), usually more 2097pid. The default size is <code>16</code> (or <code>1</code> with <code>EV_MINIMAL</code>), usually more
2045than enough. If you need to manage thousands of children you might want to 2098than enough. If you need to manage thousands of children you might want to
2046increase this value.</p> 2099increase this value (<i>must</i> be a power of two).</p>
2100 </dd>
2101 <dt>EV_INOTIFY_HASHSIZE</dt>
2102 <dd>
2103 <p><code>ev_staz</code> watchers use a small hash table to distribute workload by
2104inotify watch id. The default size is <code>16</code> (or <code>1</code> with <code>EV_MINIMAL</code>),
2105usually more than enough. If you need to manage thousands of <code>ev_stat</code>
2106watchers you might want to increase this value (<i>must</i> be a power of
2107two).</p>
2047 </dd> 2108 </dd>
2048 <dt>EV_COMMON</dt> 2109 <dt>EV_COMMON</dt>
2049 <dd> 2110 <dd>
2050 <p>By default, all watchers have a <code>void *data</code> member. By redefining 2111 <p>By default, all watchers have a <code>void *data</code> member. By redefining
2051this macro to a something else you can include more and other types of 2112this macro to a something else you can include more and other types of
… …
2097 2158
2098 2159
2099</pre> 2160</pre>
2100 2161
2101</div> 2162</div>
2102<h1 id="COMPLEXITIES">COMPLEXITIES</h1><p><a href="#TOP" class="toplink">Top</a></p> 2163<h1 id="COMPLEXITIES">COMPLEXITIES</h1>
2103<div id="COMPLEXITIES_CONTENT"> 2164<div id="COMPLEXITIES_CONTENT">
2104 <p>In this section the complexities of (many of) the algorithms used inside 2165 <p>In this section the complexities of (many of) the algorithms used inside
2105libev will be explained. For complexity discussions about backends see the 2166libev will be explained. For complexity discussions about backends see the
2106documentation for <code>ev_default_init</code>.</p> 2167documentation for <code>ev_default_init</code>.</p>
2107 <p> 2168 <p>
2108 <dl> 2169 <dl>
2109 <dt>Starting and stopping timer/periodic watchers: O(log skipped_other_timers)</dt> 2170 <dt>Starting and stopping timer/periodic watchers: O(log skipped_other_timers)</dt>
2110 <dt>Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)</dt> 2171 <dt>Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)</dt>
2111 <dt>Starting io/check/prepare/idle/signal/child watchers: O(1)</dt> 2172 <dt>Starting io/check/prepare/idle/signal/child watchers: O(1)</dt>
2112 <dt>Stopping check/prepare/idle watchers: O(1)</dt> 2173 <dt>Stopping check/prepare/idle watchers: O(1)</dt>
2113 <dt>Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % 16))</dt> 2174 <dt>Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))</dt>
2114 <dt>Finding the next timer per loop iteration: O(1)</dt> 2175 <dt>Finding the next timer per loop iteration: O(1)</dt>
2115 <dt>Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)</dt> 2176 <dt>Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)</dt>
2116 <dt>Activating one watcher: O(1)</dt> 2177 <dt>Activating one watcher: O(1)</dt>
2117 </dl> 2178 </dl>
2118 </p> 2179 </p>
… …
2120 2181
2121 2182
2122 2183
2123 2184
2124</div> 2185</div>
2125<h1 id="AUTHOR">AUTHOR</h1><p><a href="#TOP" class="toplink">Top</a></p> 2186<h1 id="AUTHOR">AUTHOR</h1>
2126<div id="AUTHOR_CONTENT"> 2187<div id="AUTHOR_CONTENT">
2127 <p>Marc Lehmann &lt;libev@schmorp.de&gt;.</p> 2188 <p>Marc Lehmann &lt;libev@schmorp.de&gt;.</p>
2128 2189
2129</div> 2190</div>
2130</div></body> 2191</div></body>

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