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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 09:20:40 2007" /> 9 <meta name="created" content="Tue Nov 27 21:29:04 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 -->
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>
… …
35<li><a href="#code_ev_child_code_watch_out_for_pro"><code>ev_child</code> - watch out for process status changes</a></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>
36<li><a href="#code_ev_stat_code_did_the_file_attri"><code>ev_stat</code> - did the file attributes just change?</a></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>
37<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> 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>
38<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> 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>
39<li><a href="#code_ev_embed_code_when_one_backend_"><code>ev_embed</code> - when one backend isn't enough...</a></li> 40<li><a href="#code_ev_embed_code_when_one_backend_"><code>ev_embed</code> - when one backend isn't enough...</a></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>
40</ul> 42</ul>
41</li> 43</li>
42<li><a href="#OTHER_FUNCTIONS">OTHER FUNCTIONS</a></li> 44<li><a href="#OTHER_FUNCTIONS">OTHER FUNCTIONS</a></li>
43<li><a href="#LIBEVENT_EMULATION">LIBEVENT EMULATION</a></li> 45<li><a href="#LIBEVENT_EMULATION">LIBEVENT EMULATION</a></li>
44<li><a href="#C_SUPPORT">C++ SUPPORT</a></li> 46<li><a href="#C_SUPPORT">C++ SUPPORT</a></li>
47<li><a href="#MACRO_MAGIC">MACRO MAGIC</a></li>
45<li><a href="#EMBEDDING">EMBEDDING</a> 48<li><a href="#EMBEDDING">EMBEDDING</a>
46<ul><li><a href="#FILESETS">FILESETS</a> 49<ul><li><a href="#FILESETS">FILESETS</a>
47<ul><li><a href="#CORE_EVENT_LOOP">CORE EVENT LOOP</a></li> 50<ul><li><a href="#CORE_EVENT_LOOP">CORE EVENT LOOP</a></li>
48<li><a href="#LIBEVENT_COMPATIBILITY_API">LIBEVENT COMPATIBILITY API</a></li> 51<li><a href="#LIBEVENT_COMPATIBILITY_API">LIBEVENT COMPATIBILITY API</a></li>
49<li><a href="#AUTOCONF_SUPPORT">AUTOCONF SUPPORT</a></li> 52<li><a href="#AUTOCONF_SUPPORT">AUTOCONF SUPPORT</a></li>
… …
57<li><a href="#AUTHOR">AUTHOR</a> 60<li><a href="#AUTHOR">AUTHOR</a>
58</li> 61</li>
59</ul><hr /> 62</ul><hr />
60<!-- INDEX END --> 63<!-- INDEX END -->
61 64
62<h1 id="NAME">NAME</h1><p><a href="#TOP" class="toplink">Top</a></p> 65<h1 id="NAME">NAME</h1>
63<div id="NAME_CONTENT"> 66<div id="NAME_CONTENT">
64<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>
65 68
66</div> 69</div>
67<h1 id="SYNOPSIS">SYNOPSIS</h1><p><a href="#TOP" class="toplink">Top</a></p> 70<h1 id="SYNOPSIS">SYNOPSIS</h1>
68<div id="SYNOPSIS_CONTENT"> 71<div id="SYNOPSIS_CONTENT">
69<pre> #include &lt;ev.h&gt; 72<pre> #include &lt;ev.h&gt;
70 73
71</pre> 74</pre>
72 75
73</div> 76</div>
74<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>
75<div id="DESCRIPTION_CONTENT"> 123<div id="DESCRIPTION_CONTENT">
76<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
77file descriptor being readable or a timeout occuring), and it will manage 125file descriptor being readable or a timeout occuring), and it will manage
78these event sources and provide your program with events.</p> 126these event sources and provide your program with events.</p>
79<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
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83watchers</i>, which are relatively small C structures you initialise with the 131watchers</i>, which are relatively small C structures you initialise with the
84details 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
85watcher.</p> 133watcher.</p>
86 134
87</div> 135</div>
88<h1 id="FEATURES">FEATURES</h1><p><a href="#TOP" class="toplink">Top</a></p> 136<h1 id="FEATURES">FEATURES</h1>
89<div id="FEATURES_CONTENT"> 137<div id="FEATURES_CONTENT">
90<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
91kqueue mechanisms for file descriptor events, relative timers, absolute 139bsd-specific <code>kqueue</code> and the solaris-specific event port mechanisms
92timers with customised rescheduling, signal events, process status change 140for file descriptor events (<code>ev_io</code>), relative timers (<code>ev_timer</code>),
93events (related to SIGCHLD), and event watchers dealing with the event 141absolute timers with customised rescheduling (<code>ev_periodic</code>), synchronous
94loop 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
95fast (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
96it to libevent for example).</p> 149for example).</p>
97 150
98</div> 151</div>
99<h1 id="CONVENTIONS">CONVENTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p> 152<h1 id="CONVENTIONS">CONVENTIONS</h1>
100<div id="CONVENTIONS_CONTENT"> 153<div id="CONVENTIONS_CONTENT">
101<p>Libev is very configurable. In this manual the default configuration 154<p>Libev is very configurable. In this manual the default configuration will
102will be described, which supports multiple event loops. For more info 155be described, which supports multiple event loops. For more info about
103about various configuration options please have a look at the file 156various configuration options please have a look at <strong>EMBED</strong> section in
104<cite>README.embed</cite> in the libev distribution. If libev was configured without 157this manual. If libev was configured without support for multiple event
105support for multiple event loops, then all functions taking an initial 158loops, then all functions taking an initial argument of name <code>loop</code>
106argument 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>
107will not have this argument.</p>
108 160
109</div> 161</div>
110<h1 id="TIME_REPRESENTATION">TIME REPRESENTATION</h1><p><a href="#TOP" class="toplink">Top</a></p> 162<h1 id="TIME_REPRESENTATION">TIME REPRESENTATION</h1>
111<div id="TIME_REPRESENTATION_CONTENT"> 163<div id="TIME_REPRESENTATION_CONTENT">
112<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
113(fractional) number of seconds since the (POSIX) epoch (somewhere near 165(fractional) number of seconds since the (POSIX) epoch (somewhere near
114the 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
115called <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
116to 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
117it, you should treat it as such.</p> 169it, you should treat it as such.</p>
118 170
119
120
121
122
123</div> 171</div>
124<h1 id="GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p> 172<h1 id="GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</h1>
125<div id="GLOBAL_FUNCTIONS_CONTENT"> 173<div id="GLOBAL_FUNCTIONS_CONTENT">
126<p>These functions can be called anytime, even before initialising the 174<p>These functions can be called anytime, even before initialising the
127library in any way.</p> 175library in any way.</p>
128<dl> 176<dl>
129 <dt>ev_tstamp ev_time ()</dt> 177 <dt>ev_tstamp ev_time ()</dt>
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142version of the library your program was compiled against.</p> 190version of the library your program was compiled against.</p>
143 <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,
144as this indicates an incompatible change. Minor versions are usually 192as this indicates an incompatible change. Minor versions are usually
145compatible to older versions, so a larger minor version alone is usually 193compatible to older versions, so a larger minor version alone is usually
146not a problem.</p> 194not a problem.</p>
147 <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
148version:</p> 196version.</p>
149<pre> assert ((&quot;libev version mismatch&quot;, 197<pre> assert ((&quot;libev version mismatch&quot;,
150 ev_version_major () == EV_VERSION_MAJOR 198 ev_version_major () == EV_VERSION_MAJOR
151 &amp;&amp; ev_version_minor () &gt;= EV_VERSION_MINOR)); 199 &amp;&amp; ev_version_minor () &gt;= EV_VERSION_MINOR));
152 200
153</pre> 201</pre>
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181might be supported on the current system, you would need to look at 229might be supported on the current system, you would need to look at
182<code>ev_embeddable_backends () &amp; ev_supported_backends ()</code>, likewise for 230<code>ev_embeddable_backends () &amp; ev_supported_backends ()</code>, likewise for
183recommended ones.</p> 231recommended ones.</p>
184 <p>See the description of <code>ev_embed</code> watchers for more info.</p> 232 <p>See the description of <code>ev_embed</code> watchers for more info.</p>
185 </dd> 233 </dd>
186 <dt>ev_set_allocator (void *(*cb)(void *ptr, long size))</dt> 234 <dt>ev_set_allocator (void *(*cb)(void *ptr, size_t size))</dt>
187 <dd> 235 <dd>
188 <p>Sets the allocation function to use (the prototype is similar to the 236 <p>Sets the allocation function to use (the prototype and semantics are
189realloc C function, the semantics are identical). It is used to allocate 237identical to the realloc C function). It is used to allocate and free
190and free memory (no surprises here). If it returns zero when memory 238memory (no surprises here). If it returns zero when memory needs to be
191needs to be allocated, the library might abort or take some potentially 239allocated, the library might abort or take some potentially destructive
192destructive action. The default is your system realloc function.</p> 240action. The default is your system realloc function.</p>
193 <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,
194free 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,
195or 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>
196 <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
197retries: better than mine).</p> 245retries).</p>
198<pre> static void * 246<pre> static void *
199 persistent_realloc (void *ptr, long size) 247 persistent_realloc (void *ptr, size_t size)
200 { 248 {
201 for (;;) 249 for (;;)
202 { 250 {
203 void *newptr = realloc (ptr, size); 251 void *newptr = realloc (ptr, size);
204 252
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221indicating the system call or subsystem causing the problem. If this 269indicating the system call or subsystem causing the problem. If this
222callback 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
223matter what, when it returns. That is, libev will generally retry the 271matter what, when it returns. That is, libev will generally retry the
224requested 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
225(such as abort).</p> 273(such as abort).</p>
226 <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>
227<pre> static void 275<pre> static void
228 fatal_error (const char *msg) 276 fatal_error (const char *msg)
229 { 277 {
230 perror (msg); 278 perror (msg);
231 abort (); 279 abort ();
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237</pre> 285</pre>
238 </dd> 286 </dd>
239</dl> 287</dl>
240 288
241</div> 289</div>
242<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>
243<div id="FUNCTIONS_CONTROLLING_THE_EVENT_LOOP-2"> 291<div id="FUNCTIONS_CONTROLLING_THE_EVENT_LOOP-2">
244<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
245types 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
246events, and dynamically created loops which do not.</p> 294events, and dynamically created loops which do not.</p>
247<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
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367 <dd> 415 <dd>
368 <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
369always distinct from the default loop. Unlike the default loop, it cannot 417always distinct from the default loop. Unlike the default loop, it cannot
370handle 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
371undefined behaviour (or a failed assertion if assertions are enabled).</p> 419undefined behaviour (or a failed assertion if assertions are enabled).</p>
372 <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>
373<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);
374 if (!epoller) 422 if (!epoller)
375 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;);
376 424
377</pre> 425</pre>
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470 be handled here by queueing them when their watcher gets executed. 518 be handled here by queueing them when their watcher gets executed.
471 - 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
472 were used, return, otherwise continue with step *. 520 were used, return, otherwise continue with step *.
473 521
474</pre> 522</pre>
475 <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
476anymore.</p> 524anymore.</p>
477<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
478 ... 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..)
479 ev_loop (my_loop, 0); 527 ev_loop (my_loop, 0);
480 ... jobs done. yeah! 528 ... jobs done. yeah!
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499example, 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
500visible 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
501no 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
502way 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
503libraries. 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>
504 <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>
505running when nothing else is active.</p> 553running when nothing else is active.</p>
506<pre> struct dv_signal exitsig; 554<pre> struct ev_signal exitsig;
507 ev_signal_init (&amp;exitsig, sig_cb, SIGINT); 555 ev_signal_init (&amp;exitsig, sig_cb, SIGINT);
508 ev_signal_start (myloop, &amp;exitsig); 556 ev_signal_start (loop, &amp;exitsig);
509 evf_unref (myloop); 557 evf_unref (loop);
510 558
511</pre> 559</pre>
512 <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>
513<pre> ev_ref (myloop); 561<pre> ev_ref (loop);
514 ev_signal_stop (myloop, &amp;exitsig); 562 ev_signal_stop (loop, &amp;exitsig);
515 563
516</pre> 564</pre>
517 </dd> 565 </dd>
518</dl> 566</dl>
519 567
520 568
521 569
522 570
523 571
524</div> 572</div>
525<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>
526<div id="ANATOMY_OF_A_WATCHER_CONTENT"> 574<div id="ANATOMY_OF_A_WATCHER_CONTENT">
527<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
528interest 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
529become 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>
530<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)
… …
606received events. Callbacks of both watcher types can start and stop as 654received events. Callbacks of both watcher types can start and stop as
607many watchers as they want, and all of them will be taken into account 655many watchers as they want, and all of them will be taken into account
608(for example, a <code>ev_prepare</code> watcher might start an idle watcher to keep 656(for example, a <code>ev_prepare</code> watcher might start an idle watcher to keep
609<code>ev_loop</code> from blocking).</p> 657<code>ev_loop</code> from blocking).</p>
610 </dd> 658 </dd>
659 <dt><code>EV_EMBED</code></dt>
660 <dd>
661 <p>The embedded event loop specified in the <code>ev_embed</code> watcher needs attention.</p>
662 </dd>
663 <dt><code>EV_FORK</code></dt>
664 <dd>
665 <p>The event loop has been resumed in the child process after fork (see
666<code>ev_fork</code>).</p>
667 </dd>
611 <dt><code>EV_ERROR</code></dt> 668 <dt><code>EV_ERROR</code></dt>
612 <dd> 669 <dd>
613 <p>An unspecified error has occured, the watcher has been stopped. This might 670 <p>An unspecified error has occured, the watcher has been stopped. This might
614happen because the watcher could not be properly started because libev 671happen because the watcher could not be properly started because libev
615ran out of memory, a file descriptor was found to be closed or any other 672ran out of memory, a file descriptor was found to be closed or any other
… …
734 791
735 792
736 793
737 794
738</div> 795</div>
739<h1 id="WATCHER_TYPES">WATCHER TYPES</h1><p><a href="#TOP" class="toplink">Top</a></p> 796<h1 id="WATCHER_TYPES">WATCHER TYPES</h1>
740<div id="WATCHER_TYPES_CONTENT"> 797<div id="WATCHER_TYPES_CONTENT">
741<p>This section describes each watcher in detail, but will not repeat 798<p>This section describes each watcher in detail, but will not repeat
742information given in the last section. Any initialisation/set macros, 799information given in the last section. Any initialisation/set macros,
743functions and members specific to the watcher type are explained.</p> 800functions and members specific to the watcher type are explained.</p>
744<p>Members are additionally marked with either <i>[read-only]</i>, meaning that, 801<p>Members are additionally marked with either <i>[read-only]</i>, meaning that,
… …
804 <dt>int events [read-only]</dt> 861 <dt>int events [read-only]</dt>
805 <dd> 862 <dd>
806 <p>The events being watched.</p> 863 <p>The events being watched.</p>
807 </dd> 864 </dd>
808</dl> 865</dl>
809<p>Example: call <code>stdin_readable_cb</code> when STDIN_FILENO has become, well 866<p>Example: Call <code>stdin_readable_cb</code> when STDIN_FILENO has become, well
810readable, but only once. Since it is likely line-buffered, you could 867readable, but only once. Since it is likely line-buffered, you could
811attempt to read a whole line in the callback:</p> 868attempt to read a whole line in the callback.</p>
812<pre> static void 869<pre> static void
813 stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents) 870 stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents)
814 { 871 {
815 ev_io_stop (loop, w); 872 ev_io_stop (loop, w);
816 .. read from stdin here (or from w-&gt;fd) and haqndle any I/O errors 873 .. read from stdin here (or from w-&gt;fd) and haqndle any I/O errors
… …
899 <p>The current <code>repeat</code> value. Will be used each time the watcher times out 956 <p>The current <code>repeat</code> value. Will be used each time the watcher times out
900or <code>ev_timer_again</code> is called and determines the next timeout (if any), 957or <code>ev_timer_again</code> is called and determines the next timeout (if any),
901which is also when any modifications are taken into account.</p> 958which is also when any modifications are taken into account.</p>
902 </dd> 959 </dd>
903</dl> 960</dl>
904<p>Example: create a timer that fires after 60 seconds.</p> 961<p>Example: Create a timer that fires after 60 seconds.</p>
905<pre> static void 962<pre> static void
906 one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) 963 one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents)
907 { 964 {
908 .. one minute over, w is actually stopped right here 965 .. one minute over, w is actually stopped right here
909 } 966 }
… …
911 struct ev_timer mytimer; 968 struct ev_timer mytimer;
912 ev_timer_init (&amp;mytimer, one_minute_cb, 60., 0.); 969 ev_timer_init (&amp;mytimer, one_minute_cb, 60., 0.);
913 ev_timer_start (loop, &amp;mytimer); 970 ev_timer_start (loop, &amp;mytimer);
914 971
915</pre> 972</pre>
916<p>Example: create a timeout timer that times out after 10 seconds of 973<p>Example: Create a timeout timer that times out after 10 seconds of
917inactivity.</p> 974inactivity.</p>
918<pre> static void 975<pre> static void
919 timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents) 976 timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents)
920 { 977 {
921 .. ten seconds without any activity 978 .. ten seconds without any activity
… …
1037 <p>The current reschedule callback, or <code>0</code>, if this functionality is 1094 <p>The current reschedule callback, or <code>0</code>, if this functionality is
1038switched off. Can be changed any time, but changes only take effect when 1095switched off. Can be changed any time, but changes only take effect when
1039the periodic timer fires or <code>ev_periodic_again</code> is being called.</p> 1096the periodic timer fires or <code>ev_periodic_again</code> is being called.</p>
1040 </dd> 1097 </dd>
1041</dl> 1098</dl>
1042<p>Example: call a callback every hour, or, more precisely, whenever the 1099<p>Example: Call a callback every hour, or, more precisely, whenever the
1043system clock is divisible by 3600. The callback invocation times have 1100system clock is divisible by 3600. The callback invocation times have
1044potentially a lot of jittering, but good long-term stability.</p> 1101potentially a lot of jittering, but good long-term stability.</p>
1045<pre> static void 1102<pre> static void
1046 clock_cb (struct ev_loop *loop, struct ev_io *w, int revents) 1103 clock_cb (struct ev_loop *loop, struct ev_io *w, int revents)
1047 { 1104 {
… …
1051 struct ev_periodic hourly_tick; 1108 struct ev_periodic hourly_tick;
1052 ev_periodic_init (&amp;hourly_tick, clock_cb, 0., 3600., 0); 1109 ev_periodic_init (&amp;hourly_tick, clock_cb, 0., 3600., 0);
1053 ev_periodic_start (loop, &amp;hourly_tick); 1110 ev_periodic_start (loop, &amp;hourly_tick);
1054 1111
1055</pre> 1112</pre>
1056<p>Example: the same as above, but use a reschedule callback to do it:</p> 1113<p>Example: The same as above, but use a reschedule callback to do it:</p>
1057<pre> #include &lt;math.h&gt; 1114<pre> #include &lt;math.h&gt;
1058 1115
1059 static ev_tstamp 1116 static ev_tstamp
1060 my_scheduler_cb (struct ev_periodic *w, ev_tstamp now) 1117 my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)
1061 { 1118 {
… …
1063 } 1120 }
1064 1121
1065 ev_periodic_init (&amp;hourly_tick, clock_cb, 0., 0., my_scheduler_cb); 1122 ev_periodic_init (&amp;hourly_tick, clock_cb, 0., 0., my_scheduler_cb);
1066 1123
1067</pre> 1124</pre>
1068<p>Example: call a callback every hour, starting now:</p> 1125<p>Example: Call a callback every hour, starting now:</p>
1069<pre> struct ev_periodic hourly_tick; 1126<pre> struct ev_periodic hourly_tick;
1070 ev_periodic_init (&amp;hourly_tick, clock_cb, 1127 ev_periodic_init (&amp;hourly_tick, clock_cb,
1071 fmod (ev_now (loop), 3600.), 3600., 0); 1128 fmod (ev_now (loop), 3600.), 3600., 0);
1072 ev_periodic_start (loop, &amp;hourly_tick); 1129 ev_periodic_start (loop, &amp;hourly_tick);
1073 1130
… …
1134 <dd> 1191 <dd>
1135 <p>The process exit/trace status caused by <code>rpid</code> (see your systems 1192 <p>The process exit/trace status caused by <code>rpid</code> (see your systems
1136<code>waitpid</code> and <code>sys/wait.h</code> documentation for details).</p> 1193<code>waitpid</code> and <code>sys/wait.h</code> documentation for details).</p>
1137 </dd> 1194 </dd>
1138</dl> 1195</dl>
1139<p>Example: try to exit cleanly on SIGINT and SIGTERM.</p> 1196<p>Example: Try to exit cleanly on SIGINT and SIGTERM.</p>
1140<pre> static void 1197<pre> static void
1141 sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) 1198 sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents)
1142 { 1199 {
1143 ev_unloop (loop, EVUNLOOP_ALL); 1200 ev_unloop (loop, EVUNLOOP_ALL);
1144 } 1201 }
… …
1267 <p>Initialises and configures the idle watcher - it has no parameters of any 1324 <p>Initialises and configures the idle watcher - it has no parameters of any
1268kind. There is a <code>ev_idle_set</code> macro, but using it is utterly pointless, 1325kind. There is a <code>ev_idle_set</code> macro, but using it is utterly pointless,
1269believe me.</p> 1326believe me.</p>
1270 </dd> 1327 </dd>
1271</dl> 1328</dl>
1272<p>Example: dynamically allocate an <code>ev_idle</code>, start it, and in the 1329<p>Example: Dynamically allocate an <code>ev_idle</code> watcher, start it, and in the
1273callback, free it. Alos, use no error checking, as usual.</p> 1330callback, free it. Also, use no error checking, as usual.</p>
1274<pre> static void 1331<pre> static void
1275 idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents) 1332 idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents)
1276 { 1333 {
1277 free (w); 1334 free (w);
1278 // now do something you wanted to do when the program has 1335 // now do something you wanted to do when the program has
… …
1480 1537
1481 1538
1482 1539
1483 1540
1484</div> 1541</div>
1485<h1 id="OTHER_FUNCTIONS">OTHER FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p> 1542<h2 id="code_ev_fork_code_the_audacity_to_re"><code>ev_fork</code> - the audacity to resume the event loop after a fork</h2>
1543<div id="code_ev_fork_code_the_audacity_to_re-2">
1544<p>Fork watchers are called when a <code>fork ()</code> was detected (usually because
1545whoever is a good citizen cared to tell libev about it by calling
1546<code>ev_default_fork</code> or <code>ev_loop_fork</code>). The invocation is done before the
1547event loop blocks next and before <code>ev_check</code> watchers are being called,
1548and only in the child after the fork. If whoever good citizen calling
1549<code>ev_default_fork</code> cheats and calls it in the wrong process, the fork
1550handlers will be invoked, too, of course.</p>
1551<dl>
1552 <dt>ev_fork_init (ev_signal *, callback)</dt>
1553 <dd>
1554 <p>Initialises and configures the fork watcher - it has no parameters of any
1555kind. There is a <code>ev_fork_set</code> macro, but using it is utterly pointless,
1556believe me.</p>
1557 </dd>
1558</dl>
1559
1560
1561
1562
1563
1564</div>
1565<h1 id="OTHER_FUNCTIONS">OTHER FUNCTIONS</h1>
1486<div id="OTHER_FUNCTIONS_CONTENT"> 1566<div id="OTHER_FUNCTIONS_CONTENT">
1487<p>There are some other functions of possible interest. Described. Here. Now.</p> 1567<p>There are some other functions of possible interest. Described. Here. Now.</p>
1488<dl> 1568<dl>
1489 <dt>ev_once (loop, int fd, int events, ev_tstamp timeout, callback)</dt> 1569 <dt>ev_once (loop, int fd, int events, ev_tstamp timeout, callback)</dt>
1490 <dd> 1570 <dd>
… …
1537 1617
1538 1618
1539 1619
1540 1620
1541</div> 1621</div>
1542<h1 id="LIBEVENT_EMULATION">LIBEVENT EMULATION</h1><p><a href="#TOP" class="toplink">Top</a></p> 1622<h1 id="LIBEVENT_EMULATION">LIBEVENT EMULATION</h1>
1543<div id="LIBEVENT_EMULATION_CONTENT"> 1623<div id="LIBEVENT_EMULATION_CONTENT">
1544<p>Libev offers a compatibility emulation layer for libevent. It cannot 1624<p>Libev offers a compatibility emulation layer for libevent. It cannot
1545emulate the internals of libevent, so here are some usage hints:</p> 1625emulate the internals of libevent, so here are some usage hints:</p>
1546<dl> 1626<dl>
1547 <dt>* Use it by including &lt;event.h&gt;, as usual.</dt> 1627 <dt>* Use it by including &lt;event.h&gt;, as usual.</dt>
… …
1557 <dt>* The libev emulation is <i>not</i> ABI compatible to libevent, you need 1637 <dt>* The libev emulation is <i>not</i> ABI compatible to libevent, you need
1558to use the libev header file and library.</dt> 1638to use the libev header file and library.</dt>
1559</dl> 1639</dl>
1560 1640
1561</div> 1641</div>
1562<h1 id="C_SUPPORT">C++ SUPPORT</h1><p><a href="#TOP" class="toplink">Top</a></p> 1642<h1 id="C_SUPPORT">C++ SUPPORT</h1>
1563<div id="C_SUPPORT_CONTENT"> 1643<div id="C_SUPPORT_CONTENT">
1564<p>Libev comes with some simplistic wrapper classes for C++ that mainly allow 1644<p>Libev comes with some simplistic wrapper classes for C++ that mainly allow
1565you to use some convinience methods to start/stop watchers and also change 1645you to use some convinience methods to start/stop watchers and also change
1566the callback model to a model using method callbacks on objects.</p> 1646the callback model to a model using method callbacks on objects.</p>
1567<p>To use it,</p> 1647<p>To use it,</p>
… …
1656 idle (this, &amp;myclass::idle_cb) 1736 idle (this, &amp;myclass::idle_cb)
1657 { 1737 {
1658 io.start (fd, ev::READ); 1738 io.start (fd, ev::READ);
1659 } 1739 }
1660 1740
1661</pre>
1662 1741
1742
1743
1744</pre>
1745
1663</div> 1746</div>
1664<h1 id="EMBEDDING">EMBEDDING</h1><p><a href="#TOP" class="toplink">Top</a></p> 1747<h1 id="MACRO_MAGIC">MACRO MAGIC</h1>
1748<div id="MACRO_MAGIC_CONTENT">
1749<p>Libev can be compiled with a variety of options, the most fundemantal is
1750<code>EV_MULTIPLICITY</code>. This option determines wether (most) functions and
1751callbacks have an initial <code>struct ev_loop *</code> argument.</p>
1752<p>To make it easier to write programs that cope with either variant, the
1753following macros are defined:</p>
1754<dl>
1755 <dt><code>EV_A</code>, <code>EV_A_</code></dt>
1756 <dd>
1757 <p>This provides the loop <i>argument</i> for functions, if one is required (&quot;ev
1758loop argument&quot;). The <code>EV_A</code> form is used when this is the sole argument,
1759<code>EV_A_</code> is used when other arguments are following. Example:</p>
1760<pre> ev_unref (EV_A);
1761 ev_timer_add (EV_A_ watcher);
1762 ev_loop (EV_A_ 0);
1763
1764</pre>
1765 <p>It assumes the variable <code>loop</code> of type <code>struct ev_loop *</code> is in scope,
1766which is often provided by the following macro.</p>
1767 </dd>
1768 <dt><code>EV_P</code>, <code>EV_P_</code></dt>
1769 <dd>
1770 <p>This provides the loop <i>parameter</i> for functions, if one is required (&quot;ev
1771loop parameter&quot;). The <code>EV_P</code> form is used when this is the sole parameter,
1772<code>EV_P_</code> is used when other parameters are following. Example:</p>
1773<pre> // this is how ev_unref is being declared
1774 static void ev_unref (EV_P);
1775
1776 // this is how you can declare your typical callback
1777 static void cb (EV_P_ ev_timer *w, int revents)
1778
1779</pre>
1780 <p>It declares a parameter <code>loop</code> of type <code>struct ev_loop *</code>, quite
1781suitable for use with <code>EV_A</code>.</p>
1782 </dd>
1783 <dt><code>EV_DEFAULT</code>, <code>EV_DEFAULT_</code></dt>
1784 <dd>
1785 <p>Similar to the other two macros, this gives you the value of the default
1786loop, if multiple loops are supported (&quot;ev loop default&quot;).</p>
1787 </dd>
1788</dl>
1789<p>Example: Declare and initialise a check watcher, working regardless of
1790wether multiple loops are supported or not.</p>
1791<pre> static void
1792 check_cb (EV_P_ ev_timer *w, int revents)
1793 {
1794 ev_check_stop (EV_A_ w);
1795 }
1796
1797 ev_check check;
1798 ev_check_init (&amp;check, check_cb);
1799 ev_check_start (EV_DEFAULT_ &amp;check);
1800 ev_loop (EV_DEFAULT_ 0);
1801
1802
1803
1804
1805</pre>
1806
1807</div>
1808<h1 id="EMBEDDING">EMBEDDING</h1>
1665<div id="EMBEDDING_CONTENT"> 1809<div id="EMBEDDING_CONTENT">
1666<p>Libev can (and often is) directly embedded into host 1810<p>Libev can (and often is) directly embedded into host
1667applications. Examples of applications that embed it include the Deliantra 1811applications. Examples of applications that embed it include the Deliantra
1668Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe) 1812Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe)
1669and rxvt-unicode.</p> 1813and rxvt-unicode.</p>
… …
1891 <dt>EV_STAT_ENABLE</dt> 2035 <dt>EV_STAT_ENABLE</dt>
1892 <dd> 2036 <dd>
1893 <p>If undefined or defined to be <code>1</code>, then stat watchers are supported. If 2037 <p>If undefined or defined to be <code>1</code>, then stat watchers are supported. If
1894defined to be <code>0</code>, then they are not.</p> 2038defined to be <code>0</code>, then they are not.</p>
1895 </dd> 2039 </dd>
2040 <dt>EV_FORK_ENABLE</dt>
2041 <dd>
2042 <p>If undefined or defined to be <code>1</code>, then fork watchers are supported. If
2043defined to be <code>0</code>, then they are not.</p>
2044 </dd>
1896 <dt>EV_MINIMAL</dt> 2045 <dt>EV_MINIMAL</dt>
1897 <dd> 2046 <dd>
1898 <p>If you need to shave off some kilobytes of code at the expense of some 2047 <p>If you need to shave off some kilobytes of code at the expense of some
1899speed, define this symbol to <code>1</code>. Currently only used for gcc to override 2048speed, define this symbol to <code>1</code>. Currently only used for gcc to override
1900some inlining decisions, saves roughly 30% codesize of amd64.</p> 2049some inlining decisions, saves roughly 30% codesize of amd64.</p>
2050 </dd>
2051 <dt>EV_PID_HASHSIZE</dt>
2052 <dd>
2053 <p><code>ev_child</code> watchers use a small hash table to distribute workload by
2054pid. The default size is <code>16</code> (or <code>1</code> with <code>EV_MINIMAL</code>), usually more
2055than enough. If you need to manage thousands of children you might want to
2056increase this value.</p>
1901 </dd> 2057 </dd>
1902 <dt>EV_COMMON</dt> 2058 <dt>EV_COMMON</dt>
1903 <dd> 2059 <dd>
1904 <p>By default, all watchers have a <code>void *data</code> member. By redefining 2060 <p>By default, all watchers have a <code>void *data</code> member. By redefining
1905this macro to a something else you can include more and other types of 2061this macro to a something else you can include more and other types of
… …
1951 2107
1952 2108
1953</pre> 2109</pre>
1954 2110
1955</div> 2111</div>
1956<h1 id="COMPLEXITIES">COMPLEXITIES</h1><p><a href="#TOP" class="toplink">Top</a></p> 2112<h1 id="COMPLEXITIES">COMPLEXITIES</h1>
1957<div id="COMPLEXITIES_CONTENT"> 2113<div id="COMPLEXITIES_CONTENT">
1958 <p>In this section the complexities of (many of) the algorithms used inside 2114 <p>In this section the complexities of (many of) the algorithms used inside
1959libev will be explained. For complexity discussions about backends see the 2115libev will be explained. For complexity discussions about backends see the
1960documentation for <code>ev_default_init</code>.</p> 2116documentation for <code>ev_default_init</code>.</p>
1961 <p> 2117 <p>
… …
1974 2130
1975 2131
1976 2132
1977 2133
1978</div> 2134</div>
1979<h1 id="AUTHOR">AUTHOR</h1><p><a href="#TOP" class="toplink">Top</a></p> 2135<h1 id="AUTHOR">AUTHOR</h1>
1980<div id="AUTHOR_CONTENT"> 2136<div id="AUTHOR_CONTENT">
1981 <p>Marc Lehmann &lt;libev@schmorp.de&gt;.</p> 2137 <p>Marc Lehmann &lt;libev@schmorp.de&gt;.</p>
1982 2138
1983</div> 2139</div>
1984</div></body> 2140</div></body>

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