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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="Sat Nov 24 11:15:15 2007" /> 9 <meta name="created" content="Wed Nov 28 12:31:29 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>
24<li><a href="#FUNCTIONS_CONTROLLING_THE_EVENT_LOOP">FUNCTIONS CONTROLLING THE EVENT LOOP</a></li> 25<li><a href="#FUNCTIONS_CONTROLLING_THE_EVENT_LOOP">FUNCTIONS CONTROLLING THE EVENT LOOP</a></li>
25<li><a href="#ANATOMY_OF_A_WATCHER">ANATOMY OF A WATCHER</a> 26<li><a href="#ANATOMY_OF_A_WATCHER">ANATOMY OF A WATCHER</a>
26<ul><li><a href="#SUMMARY_OF_GENERIC_WATCHER_FUNCTIONS">SUMMARY OF GENERIC WATCHER FUNCTIONS</a></li> 27<ul><li><a href="#GENERIC_WATCHER_FUNCTIONS">GENERIC WATCHER FUNCTIONS</a></li>
27<li><a href="#ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH">ASSOCIATING CUSTOM DATA WITH A WATCHER</a></li> 28<li><a href="#ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH">ASSOCIATING CUSTOM DATA WITH A WATCHER</a></li>
28</ul> 29</ul>
29</li> 30</li>
30<li><a href="#WATCHER_TYPES">WATCHER TYPES</a> 31<li><a href="#WATCHER_TYPES">WATCHER TYPES</a>
31<ul><li><a href="#code_ev_io_code_is_this_file_descrip"><code>ev_io</code> - is this file descriptor readable or writable</a></li> 32<ul><li><a href="#code_ev_io_code_is_this_file_descrip"><code>ev_io</code> - is this file descriptor readable or writable?</a></li>
32<li><a href="#code_ev_timer_code_relative_and_opti"><code>ev_timer</code> - relative and optionally recurring timeouts</a></li> 33<li><a href="#code_ev_timer_code_relative_and_opti"><code>ev_timer</code> - relative and optionally repeating timeouts</a></li>
33<li><a href="#code_ev_periodic_code_to_cron_or_not"><code>ev_periodic</code> - to cron or not to cron</a></li> 34<li><a href="#code_ev_periodic_code_to_cron_or_not"><code>ev_periodic</code> - to cron or not to cron?</a></li>
34<li><a href="#code_ev_signal_code_signal_me_when_a"><code>ev_signal</code> - signal me when a signal gets signalled</a></li> 35<li><a href="#code_ev_signal_code_signal_me_when_a"><code>ev_signal</code> - signal me when a signal gets signalled!</a></li>
35<li><a href="#code_ev_child_code_wait_for_pid_stat"><code>ev_child</code> - wait for pid 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>
37<li><a href="#code_ev_stat_code_did_the_file_attri"><code>ev_stat</code> - did the file attributes just change?</a></li>
36<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>
37<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>
38<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>
39</ul> 42</ul>
40</li> 43</li>
41<li><a href="#OTHER_FUNCTIONS">OTHER FUNCTIONS</a></li> 44<li><a href="#OTHER_FUNCTIONS">OTHER FUNCTIONS</a></li>
42<li><a href="#LIBEVENT_EMULATION">LIBEVENT EMULATION</a></li> 45<li><a href="#LIBEVENT_EMULATION">LIBEVENT EMULATION</a></li>
43<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>
44<li><a href="#EMBEDDING">EMBEDDING</a> 48<li><a href="#EMBEDDING">EMBEDDING</a>
45<ul><li><a href="#FILESETS">FILESETS</a> 49<ul><li><a href="#FILESETS">FILESETS</a>
46<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>
47<li><a href="#LIBEVENT_COMPATIBILITY_API">LIBEVENT COMPATIBILITY API</a></li> 51<li><a href="#LIBEVENT_COMPATIBILITY_API">LIBEVENT COMPATIBILITY API</a></li>
48<li><a href="#AUTOCONF_SUPPORT">AUTOCONF SUPPORT</a></li> 52<li><a href="#AUTOCONF_SUPPORT">AUTOCONF SUPPORT</a></li>
… …
50</li> 54</li>
51<li><a href="#PREPROCESSOR_SYMBOLS_MACROS">PREPROCESSOR SYMBOLS/MACROS</a></li> 55<li><a href="#PREPROCESSOR_SYMBOLS_MACROS">PREPROCESSOR SYMBOLS/MACROS</a></li>
52<li><a href="#EXAMPLES">EXAMPLES</a></li> 56<li><a href="#EXAMPLES">EXAMPLES</a></li>
53</ul> 57</ul>
54</li> 58</li>
59<li><a href="#COMPLEXITIES">COMPLEXITIES</a></li>
55<li><a href="#AUTHOR">AUTHOR</a> 60<li><a href="#AUTHOR">AUTHOR</a>
56</li> 61</li>
57</ul><hr /> 62</ul><hr />
58<!-- INDEX END --> 63<!-- INDEX END -->
59 64
60<h1 id="NAME">NAME</h1><p><a href="#TOP" class="toplink">Top</a></p> 65<h1 id="NAME">NAME</h1>
61<div id="NAME_CONTENT"> 66<div id="NAME_CONTENT">
62<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>
63 68
64</div> 69</div>
65<h1 id="SYNOPSIS">SYNOPSIS</h1><p><a href="#TOP" class="toplink">Top</a></p> 70<h1 id="SYNOPSIS">SYNOPSIS</h1>
66<div id="SYNOPSIS_CONTENT"> 71<div id="SYNOPSIS_CONTENT">
67<pre> #include &lt;ev.h&gt; 72<pre> #include &lt;ev.h&gt;
68 73
69</pre> 74</pre>
70 75
71</div> 76</div>
72<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>
73<div id="DESCRIPTION_CONTENT"> 123<div id="DESCRIPTION_CONTENT">
74<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
75file descriptor being readable or a timeout occuring), and it will manage 125file descriptor being readable or a timeout occuring), and it will manage
76these event sources and provide your program with events.</p> 126these event sources and provide your program with events.</p>
77<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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81watchers</i>, which are relatively small C structures you initialise with the 131watchers</i>, which are relatively small C structures you initialise with the
82details 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
83watcher.</p> 133watcher.</p>
84 134
85</div> 135</div>
86<h1 id="FEATURES">FEATURES</h1><p><a href="#TOP" class="toplink">Top</a></p> 136<h1 id="FEATURES">FEATURES</h1>
87<div id="FEATURES_CONTENT"> 137<div id="FEATURES_CONTENT">
88<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
89kqueue mechanisms for file descriptor events, relative timers, absolute 139BSD-specific <code>kqueue</code> and the Solaris-specific event port mechanisms
90timers with customised rescheduling, signal events, process status change 140for file descriptor events (<code>ev_io</code>), the Linux <code>inotify</code> interface
91events (related to SIGCHLD), and event watchers dealing with the event 141(for <code>ev_stat</code>), relative timers (<code>ev_timer</code>), absolute timers
92loop 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
93fast (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
94it to libevent for example).</p> 150for example).</p>
95 151
96</div> 152</div>
97<h1 id="CONVENTIONS">CONVENTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p> 153<h1 id="CONVENTIONS">CONVENTIONS</h1>
98<div id="CONVENTIONS_CONTENT"> 154<div id="CONVENTIONS_CONTENT">
99<p>Libev is very configurable. In this manual the default configuration 155<p>Libev is very configurable. In this manual the default configuration will
100will be described, which supports multiple event loops. For more info 156be described, which supports multiple event loops. For more info about
101about various configuration options please have a look at the file 157various configuration options please have a look at <strong>EMBED</strong> section in
102<cite>README.embed</cite> in the libev distribution. If libev was configured without 158this manual. If libev was configured without support for multiple event
103support for multiple event loops, then all functions taking an initial 159loops, then all functions taking an initial argument of name <code>loop</code>
104argument 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>
105will not have this argument.</p>
106 161
107</div> 162</div>
108<h1 id="TIME_REPRESENTATION">TIME REPRESENTATION</h1><p><a href="#TOP" class="toplink">Top</a></p> 163<h1 id="TIME_REPRESENTATION">TIME REPRESENTATION</h1>
109<div id="TIME_REPRESENTATION_CONTENT"> 164<div id="TIME_REPRESENTATION_CONTENT">
110<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
111(fractional) number of seconds since the (POSIX) epoch (somewhere near 166(fractional) number of seconds since the (POSIX) epoch (somewhere near
112the 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
113called <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
114to 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
115it, you should treat it as such.</p> 170it, you should treat it as such.</p>
116 171
117
118
119
120
121</div> 172</div>
122<h1 id="GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p> 173<h1 id="GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</h1>
123<div id="GLOBAL_FUNCTIONS_CONTENT"> 174<div id="GLOBAL_FUNCTIONS_CONTENT">
124<p>These functions can be called anytime, even before initialising the 175<p>These functions can be called anytime, even before initialising the
125library in any way.</p> 176library in any way.</p>
126<dl> 177<dl>
127 <dt>ev_tstamp ev_time ()</dt> 178 <dt>ev_tstamp ev_time ()</dt>
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140version of the library your program was compiled against.</p> 191version of the library your program was compiled against.</p>
141 <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,
142as this indicates an incompatible change. Minor versions are usually 193as this indicates an incompatible change. Minor versions are usually
143compatible to older versions, so a larger minor version alone is usually 194compatible to older versions, so a larger minor version alone is usually
144not a problem.</p> 195not a problem.</p>
145 <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
146version:</p> 197version.</p>
147<pre> assert ((&quot;libev version mismatch&quot;, 198<pre> assert ((&quot;libev version mismatch&quot;,
148 ev_version_major () == EV_VERSION_MAJOR 199 ev_version_major () == EV_VERSION_MAJOR
149 &amp;&amp; ev_version_minor () &gt;= EV_VERSION_MINOR)); 200 &amp;&amp; ev_version_minor () &gt;= EV_VERSION_MINOR));
150 201
151</pre> 202</pre>
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179might 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
180<code>ev_embeddable_backends () &amp; ev_supported_backends ()</code>, likewise for 231<code>ev_embeddable_backends () &amp; ev_supported_backends ()</code>, likewise for
181recommended ones.</p> 232recommended ones.</p>
182 <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>
183 </dd> 234 </dd>
184 <dt>ev_set_allocator (void *(*cb)(void *ptr, long size))</dt> 235 <dt>ev_set_allocator (void *(*cb)(void *ptr, size_t size))</dt>
185 <dd> 236 <dd>
186 <p>Sets the allocation function to use (the prototype is similar to the 237 <p>Sets the allocation function to use (the prototype and semantics are
187realloc C function, the semantics are identical). It is used to allocate 238identical to the realloc C function). It is used to allocate and free
188and free memory (no surprises here). If it returns zero when memory 239memory (no surprises here). If it returns zero when memory needs to be
189needs to be allocated, the library might abort or take some potentially 240allocated, the library might abort or take some potentially destructive
190destructive action. The default is your system realloc function.</p> 241action. The default is your system realloc function.</p>
191 <p>You could override this function in high-availability programs to, say, 242 <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, 243free 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> 244or 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 245 <p>Example: Replace the libev allocator with one that waits a bit and then
195retries: better than mine).</p> 246retries).</p>
196<pre> static void * 247<pre> static void *
197 persistent_realloc (void *ptr, long size) 248 persistent_realloc (void *ptr, size_t size)
198 { 249 {
199 for (;;) 250 for (;;)
200 { 251 {
201 void *newptr = realloc (ptr, size); 252 void *newptr = realloc (ptr, size);
202 253
… …
219indicating the system call or subsystem causing the problem. If this 270indicating the system call or subsystem causing the problem. If this
220callback is set, then libev will expect it to remedy the sitution, no 271callback is set, then libev will expect it to remedy the sitution, no
221matter what, when it returns. That is, libev will generally retry the 272matter what, when it returns. That is, libev will generally retry the
222requested operation, or, if the condition doesn't go away, do bad stuff 273requested operation, or, if the condition doesn't go away, do bad stuff
223(such as abort).</p> 274(such as abort).</p>
224 <p>Example: do the same thing as libev does internally:</p> 275 <p>Example: This is basically the same thing that libev does internally, too.</p>
225<pre> static void 276<pre> static void
226 fatal_error (const char *msg) 277 fatal_error (const char *msg)
227 { 278 {
228 perror (msg); 279 perror (msg);
229 abort (); 280 abort ();
… …
235</pre> 286</pre>
236 </dd> 287 </dd>
237</dl> 288</dl>
238 289
239</div> 290</div>
240<h1 id="FUNCTIONS_CONTROLLING_THE_EVENT_LOOP">FUNCTIONS CONTROLLING THE EVENT LOOP</h1><p><a href="#TOP" class="toplink">Top</a></p> 291<h1 id="FUNCTIONS_CONTROLLING_THE_EVENT_LOOP">FUNCTIONS CONTROLLING THE EVENT LOOP</h1>
241<div id="FUNCTIONS_CONTROLLING_THE_EVENT_LOOP-2"> 292<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 293<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 294types of such loops, the <i>default</i> loop, which supports signals and child
244events, and dynamically created loops which do not.</p> 295events, and dynamically created loops which do not.</p>
245<p>If you use threads, a common model is to run the default event loop 296<p>If you use threads, a common model is to run the default event loop
… …
365 <dd> 416 <dd>
366 <p>Similar to <code>ev_default_loop</code>, but always creates a new event loop that is 417 <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 418always 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 419handle signal and child watchers, and attempts to do so will be greeted by
369undefined behaviour (or a failed assertion if assertions are enabled).</p> 420undefined 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> 421 <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); 422<pre> struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);
372 if (!epoller) 423 if (!epoller)
373 fatal (&quot;no epoll found here, maybe it hides under your chair&quot;); 424 fatal (&quot;no epoll found here, maybe it hides under your chair&quot;);
374 425
375</pre> 426</pre>
… …
468 be handled here by queueing them when their watcher gets executed. 519 be handled here by queueing them when their watcher gets executed.
469 - If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK 520 - If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK
470 were used, return, otherwise continue with step *. 521 were used, return, otherwise continue with step *.
471 522
472</pre> 523</pre>
473 <p>Example: queue some jobs and then loop until no events are outsanding 524 <p>Example: Queue some jobs and then loop until no events are outsanding
474anymore.</p> 525anymore.</p>
475<pre> ... queue jobs here, make sure they register event watchers as long 526<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..) 527 ... as they still have work to do (even an idle watcher will do..)
477 ev_loop (my_loop, 0); 528 ev_loop (my_loop, 0);
478 ... jobs done. yeah! 529 ... jobs done. yeah!
… …
497example, libev itself uses this for its internal signal pipe: It is not 548example, 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 549visible 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 550no 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 551way 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> 552libraries. 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> 553 <p>Example: Create a signal watcher, but keep it from keeping <code>ev_loop</code>
503running when nothing else is active.</p> 554running when nothing else is active.</p>
504<pre> struct dv_signal exitsig; 555<pre> struct ev_signal exitsig;
505 ev_signal_init (&amp;exitsig, sig_cb, SIGINT); 556 ev_signal_init (&amp;exitsig, sig_cb, SIGINT);
506 ev_signal_start (myloop, &amp;exitsig); 557 ev_signal_start (loop, &amp;exitsig);
507 evf_unref (myloop); 558 evf_unref (loop);
508 559
509</pre> 560</pre>
510 <p>Example: for some weird reason, unregister the above signal handler again.</p> 561 <p>Example: For some weird reason, unregister the above signal handler again.</p>
511<pre> ev_ref (myloop); 562<pre> ev_ref (loop);
512 ev_signal_stop (myloop, &amp;exitsig); 563 ev_signal_stop (loop, &amp;exitsig);
513 564
514</pre> 565</pre>
515 </dd> 566 </dd>
516</dl> 567</dl>
517 568
569
570
571
572
518</div> 573</div>
519<h1 id="ANATOMY_OF_A_WATCHER">ANATOMY OF A WATCHER</h1><p><a href="#TOP" class="toplink">Top</a></p> 574<h1 id="ANATOMY_OF_A_WATCHER">ANATOMY OF A WATCHER</h1>
520<div id="ANATOMY_OF_A_WATCHER_CONTENT"> 575<div id="ANATOMY_OF_A_WATCHER_CONTENT">
521<p>A watcher is a structure that you create and register to record your 576<p>A watcher is a structure that you create and register to record your
522interest in some event. For instance, if you want to wait for STDIN to 577interest in some event. For instance, if you want to wait for STDIN to
523become readable, you would create an <code>ev_io</code> watcher for that:</p> 578become readable, you would create an <code>ev_io</code> watcher for that:</p>
524<pre> static void my_cb (struct ev_loop *loop, struct ev_io *w, int revents) 579<pre> static void my_cb (struct ev_loop *loop, struct ev_io *w, int revents)
… …
581 </dd> 636 </dd>
582 <dt><code>EV_CHILD</code></dt> 637 <dt><code>EV_CHILD</code></dt>
583 <dd> 638 <dd>
584 <p>The pid specified in the <code>ev_child</code> watcher has received a status change.</p> 639 <p>The pid specified in the <code>ev_child</code> watcher has received a status change.</p>
585 </dd> 640 </dd>
641 <dt><code>EV_STAT</code></dt>
642 <dd>
643 <p>The path specified in the <code>ev_stat</code> watcher changed its attributes somehow.</p>
644 </dd>
586 <dt><code>EV_IDLE</code></dt> 645 <dt><code>EV_IDLE</code></dt>
587 <dd> 646 <dd>
588 <p>The <code>ev_idle</code> watcher has determined that you have nothing better to do.</p> 647 <p>The <code>ev_idle</code> watcher has determined that you have nothing better to do.</p>
589 </dd> 648 </dd>
590 <dt><code>EV_PREPARE</code></dt> 649 <dt><code>EV_PREPARE</code></dt>
… …
595<code>ev_loop</code> has gathered them, but before it invokes any callbacks for any 654<code>ev_loop</code> has gathered them, but before it invokes any callbacks for any
596received events. Callbacks of both watcher types can start and stop as 655received events. Callbacks of both watcher types can start and stop as
597many watchers as they want, and all of them will be taken into account 656many watchers as they want, and all of them will be taken into account
598(for example, a <code>ev_prepare</code> watcher might start an idle watcher to keep 657(for example, a <code>ev_prepare</code> watcher might start an idle watcher to keep
599<code>ev_loop</code> from blocking).</p> 658<code>ev_loop</code> from blocking).</p>
659 </dd>
660 <dt><code>EV_EMBED</code></dt>
661 <dd>
662 <p>The embedded event loop specified in the <code>ev_embed</code> watcher needs attention.</p>
663 </dd>
664 <dt><code>EV_FORK</code></dt>
665 <dd>
666 <p>The event loop has been resumed in the child process after fork (see
667<code>ev_fork</code>).</p>
600 </dd> 668 </dd>
601 <dt><code>EV_ERROR</code></dt> 669 <dt><code>EV_ERROR</code></dt>
602 <dd> 670 <dd>
603 <p>An unspecified error has occured, the watcher has been stopped. This might 671 <p>An unspecified error has occured, the watcher has been stopped. This might
604happen because the watcher could not be properly started because libev 672happen because the watcher could not be properly started because libev
… …
612programs, though, so beware.</p> 680programs, though, so beware.</p>
613 </dd> 681 </dd>
614</dl> 682</dl>
615 683
616</div> 684</div>
617<h2 id="SUMMARY_OF_GENERIC_WATCHER_FUNCTIONS">SUMMARY OF GENERIC WATCHER FUNCTIONS</h2> 685<h2 id="GENERIC_WATCHER_FUNCTIONS">GENERIC WATCHER FUNCTIONS</h2>
618<div id="SUMMARY_OF_GENERIC_WATCHER_FUNCTIONS-2"> 686<div id="GENERIC_WATCHER_FUNCTIONS_CONTENT">
619<p>In the following description, <code>TYPE</code> stands for the watcher type, 687<p>In the following description, <code>TYPE</code> stands for the watcher type,
620e.g. <code>timer</code> for <code>ev_timer</code> watchers and <code>io</code> for <code>ev_io</code> watchers.</p> 688e.g. <code>timer</code> for <code>ev_timer</code> watchers and <code>io</code> for <code>ev_io</code> watchers.</p>
621<dl> 689<dl>
622 <dt><code>ev_init</code> (ev_TYPE *watcher, callback)</dt> 690 <dt><code>ev_init</code> (ev_TYPE *watcher, callback)</dt>
623 <dd> 691 <dd>
… …
627the type-specific <code>ev_TYPE_set</code> macro afterwards to initialise the 695the type-specific <code>ev_TYPE_set</code> macro afterwards to initialise the
628type-specific parts. For each type there is also a <code>ev_TYPE_init</code> macro 696type-specific parts. For each type there is also a <code>ev_TYPE_init</code> macro
629which rolls both calls into one.</p> 697which rolls both calls into one.</p>
630 <p>You can reinitialise a watcher at any time as long as it has been stopped 698 <p>You can reinitialise a watcher at any time as long as it has been stopped
631(or never started) and there are no pending events outstanding.</p> 699(or never started) and there are no pending events outstanding.</p>
632 <p>The callbakc is always of type <code>void (*)(ev_loop *loop, ev_TYPE *watcher, 700 <p>The callback is always of type <code>void (*)(ev_loop *loop, ev_TYPE *watcher,
633int revents)</code>.</p> 701int revents)</code>.</p>
634 </dd> 702 </dd>
635 <dt><code>ev_TYPE_set</code> (ev_TYPE *, [args])</dt> 703 <dt><code>ev_TYPE_set</code> (ev_TYPE *, [args])</dt>
636 <dd> 704 <dd>
637 <p>This macro initialises the type-specific parts of a watcher. You need to 705 <p>This macro initialises the type-specific parts of a watcher. You need to
… …
674events but its callback has not yet been invoked). As long as a watcher 742events but its callback has not yet been invoked). As long as a watcher
675is pending (but not active) you must not call an init function on it (but 743is pending (but not active) you must not call an init function on it (but
676<code>ev_TYPE_set</code> is safe) and you must make sure the watcher is available to 744<code>ev_TYPE_set</code> is safe) and you must make sure the watcher is available to
677libev (e.g. you cnanot <code>free ()</code> it).</p> 745libev (e.g. you cnanot <code>free ()</code> it).</p>
678 </dd> 746 </dd>
679 <dt>callback = ev_cb (ev_TYPE *watcher)</dt> 747 <dt>callback ev_cb (ev_TYPE *watcher)</dt>
680 <dd> 748 <dd>
681 <p>Returns the callback currently set on the watcher.</p> 749 <p>Returns the callback currently set on the watcher.</p>
682 </dd> 750 </dd>
683 <dt>ev_cb_set (ev_TYPE *watcher, callback)</dt> 751 <dt>ev_cb_set (ev_TYPE *watcher, callback)</dt>
684 <dd> 752 <dd>
… …
716 struct my_io *w = (struct my_io *)w_; 784 struct my_io *w = (struct my_io *)w_;
717 ... 785 ...
718 } 786 }
719 787
720</pre> 788</pre>
721<p>More interesting and less C-conformant ways of catsing your callback type 789<p>More interesting and less C-conformant ways of casting your callback type
722have been omitted....</p> 790instead have been omitted.</p>
791<p>Another common scenario is having some data structure with multiple
792watchers:</p>
793<pre> struct my_biggy
794 {
795 int some_data;
796 ev_timer t1;
797 ev_timer t2;
798 }
723 799
800</pre>
801<p>In this case getting the pointer to <code>my_biggy</code> is a bit more complicated,
802you need to use <code>offsetof</code>:</p>
803<pre> #include &lt;stddef.h&gt;
724 804
805 static void
806 t1_cb (EV_P_ struct ev_timer *w, int revents)
807 {
808 struct my_biggy big = (struct my_biggy *
809 (((char *)w) - offsetof (struct my_biggy, t1));
810 }
725 811
812 static void
813 t2_cb (EV_P_ struct ev_timer *w, int revents)
814 {
815 struct my_biggy big = (struct my_biggy *
816 (((char *)w) - offsetof (struct my_biggy, t2));
817 }
726 818
727 819
820
821
822</pre>
823
728</div> 824</div>
729<h1 id="WATCHER_TYPES">WATCHER TYPES</h1><p><a href="#TOP" class="toplink">Top</a></p> 825<h1 id="WATCHER_TYPES">WATCHER TYPES</h1>
730<div id="WATCHER_TYPES_CONTENT"> 826<div id="WATCHER_TYPES_CONTENT">
731<p>This section describes each watcher in detail, but will not repeat 827<p>This section describes each watcher in detail, but will not repeat
732information given in the last section.</p> 828information given in the last section. Any initialisation/set macros,
829functions and members specific to the watcher type are explained.</p>
830<p>Members are additionally marked with either <i>[read-only]</i>, meaning that,
831while the watcher is active, you can look at the member and expect some
832sensible content, but you must not modify it (you can modify it while the
833watcher is stopped to your hearts content), or <i>[read-write]</i>, which
834means you can expect it to have some sensible content while the watcher
835is active, but you can also modify it. Modifying it may not do something
836sensible or take immediate effect (or do anything at all), but libev will
837not crash or malfunction in any way.</p>
733 838
734 839
735 840
736 841
737 842
738</div> 843</div>
739<h2 id="code_ev_io_code_is_this_file_descrip"><code>ev_io</code> - is this file descriptor readable or writable</h2> 844<h2 id="code_ev_io_code_is_this_file_descrip"><code>ev_io</code> - is this file descriptor readable or writable?</h2>
740<div id="code_ev_io_code_is_this_file_descrip-2"> 845<div id="code_ev_io_code_is_this_file_descrip-2">
741<p>I/O watchers check whether a file descriptor is readable or writable 846<p>I/O watchers check whether a file descriptor is readable or writable
742in each iteration of the event loop (This behaviour is called 847in each iteration of the event loop, or, more precisely, when reading
743level-triggering because you keep receiving events as long as the 848would not block the process and writing would at least be able to write
744condition persists. Remember you can stop the watcher if you don't want to 849some data. This behaviour is called level-triggering because you keep
745act on the event and neither want to receive future events).</p> 850receiving events as long as the condition persists. Remember you can stop
851the watcher if you don't want to act on the event and neither want to
852receive future events.</p>
746<p>In general you can register as many read and/or write event watchers per 853<p>In general you can register as many read and/or write event watchers per
747fd as you want (as long as you don't confuse yourself). Setting all file 854fd as you want (as long as you don't confuse yourself). Setting all file
748descriptors to non-blocking mode is also usually a good idea (but not 855descriptors to non-blocking mode is also usually a good idea (but not
749required if you know what you are doing).</p> 856required if you know what you are doing).</p>
750<p>You have to be careful with dup'ed file descriptors, though. Some backends 857<p>You have to be careful with dup'ed file descriptors, though. Some backends
751(the linux epoll backend is a notable example) cannot handle dup'ed file 858(the linux epoll backend is a notable example) cannot handle dup'ed file
752descriptors correctly if you register interest in two or more fds pointing 859descriptors correctly if you register interest in two or more fds pointing
753to the same underlying file/socket etc. description (that is, they share 860to the same underlying file/socket/etc. description (that is, they share
754the same underlying &quot;file open&quot;).</p> 861the same underlying &quot;file open&quot;).</p>
755<p>If you must do this, then force the use of a known-to-be-good backend 862<p>If you must do this, then force the use of a known-to-be-good backend
756(at the time of this writing, this includes only <code>EVBACKEND_SELECT</code> and 863(at the time of this writing, this includes only <code>EVBACKEND_SELECT</code> and
757<code>EVBACKEND_POLL</code>).</p> 864<code>EVBACKEND_POLL</code>).</p>
865<p>Another thing you have to watch out for is that it is quite easy to
866receive &quot;spurious&quot; readyness notifications, that is your callback might
867be called with <code>EV_READ</code> but a subsequent <code>read</code>(2) will actually block
868because there is no data. Not only are some backends known to create a
869lot of those (for example solaris ports), it is very easy to get into
870this situation even with a relatively standard program structure. Thus
871it is best to always use non-blocking I/O: An extra <code>read</code>(2) returning
872<code>EAGAIN</code> is far preferable to a program hanging until some data arrives.</p>
873<p>If you cannot run the fd in non-blocking mode (for example you should not
874play around with an Xlib connection), then you have to seperately re-test
875wether a file descriptor is really ready with a known-to-be good interface
876such as poll (fortunately in our Xlib example, Xlib already does this on
877its own, so its quite safe to use).</p>
758<dl> 878<dl>
759 <dt>ev_io_init (ev_io *, callback, int fd, int events)</dt> 879 <dt>ev_io_init (ev_io *, callback, int fd, int events)</dt>
760 <dt>ev_io_set (ev_io *, int fd, int events)</dt> 880 <dt>ev_io_set (ev_io *, int fd, int events)</dt>
761 <dd> 881 <dd>
762 <p>Configures an <code>ev_io</code> watcher. The fd is the file descriptor to rceeive 882 <p>Configures an <code>ev_io</code> watcher. The <code>fd</code> is the file descriptor to
763events for and events is either <code>EV_READ</code>, <code>EV_WRITE</code> or <code>EV_READ | 883rceeive events for and events is either <code>EV_READ</code>, <code>EV_WRITE</code> or
764EV_WRITE</code> to receive the given events.</p> 884<code>EV_READ | EV_WRITE</code> to receive the given events.</p>
765 <p>Please note that most of the more scalable backend mechanisms (for example 885 </dd>
766epoll and solaris ports) can result in spurious readyness notifications 886 <dt>int fd [read-only]</dt>
767for file descriptors, so you practically need to use non-blocking I/O (and 887 <dd>
768treat callback invocation as hint only), or retest separately with a safe 888 <p>The file descriptor being watched.</p>
769interface before doing I/O (XLib can do this), or force the use of either 889 </dd>
770<code>EVBACKEND_SELECT</code> or <code>EVBACKEND_POLL</code>, which don't suffer from this 890 <dt>int events [read-only]</dt>
771problem. Also note that it is quite easy to have your callback invoked 891 <dd>
772when the readyness condition is no longer valid even when employing 892 <p>The events being watched.</p>
773typical ways of handling events, so its a good idea to use non-blocking
774I/O unconditionally.</p>
775 </dd> 893 </dd>
776</dl> 894</dl>
777<p>Example: call <code>stdin_readable_cb</code> when STDIN_FILENO has become, well 895<p>Example: Call <code>stdin_readable_cb</code> when STDIN_FILENO has become, well
778readable, but only once. Since it is likely line-buffered, you could 896readable, but only once. Since it is likely line-buffered, you could
779attempt to read a whole line in the callback:</p> 897attempt to read a whole line in the callback.</p>
780<pre> static void 898<pre> static void
781 stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents) 899 stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents)
782 { 900 {
783 ev_io_stop (loop, w); 901 ev_io_stop (loop, w);
784 .. read from stdin here (or from w-&gt;fd) and haqndle any I/O errors 902 .. read from stdin here (or from w-&gt;fd) and haqndle any I/O errors
… …
795 913
796 914
797</pre> 915</pre>
798 916
799</div> 917</div>
800<h2 id="code_ev_timer_code_relative_and_opti"><code>ev_timer</code> - relative and optionally recurring timeouts</h2> 918<h2 id="code_ev_timer_code_relative_and_opti"><code>ev_timer</code> - relative and optionally repeating timeouts</h2>
801<div id="code_ev_timer_code_relative_and_opti-2"> 919<div id="code_ev_timer_code_relative_and_opti-2">
802<p>Timer watchers are simple relative timers that generate an event after a 920<p>Timer watchers are simple relative timers that generate an event after a
803given time, and optionally repeating in regular intervals after that.</p> 921given time, and optionally repeating in regular intervals after that.</p>
804<p>The timers are based on real time, that is, if you register an event that 922<p>The timers are based on real time, that is, if you register an event that
805times out after an hour and you reset your system clock to last years 923times out after an hour and you reset your system clock to last years
… …
837repeating. The exact semantics are:</p> 955repeating. The exact semantics are:</p>
838 <p>If the timer is started but nonrepeating, stop it.</p> 956 <p>If the timer is started but nonrepeating, stop it.</p>
839 <p>If the timer is repeating, either start it if necessary (with the repeat 957 <p>If the timer is repeating, either start it if necessary (with the repeat
840value), or reset the running timer to the repeat value.</p> 958value), or reset the running timer to the repeat value.</p>
841 <p>This sounds a bit complicated, but here is a useful and typical 959 <p>This sounds a bit complicated, but here is a useful and typical
842example: Imagine you have a tcp connection and you want a so-called idle 960example: Imagine you have a tcp connection and you want a so-called
843timeout, that is, you want to be called when there have been, say, 60 961idle timeout, that is, you want to be called when there have been,
844seconds of inactivity on the socket. The easiest way to do this is to 962say, 60 seconds of inactivity on the socket. The easiest way to do
845configure an <code>ev_timer</code> with after=repeat=60 and calling ev_timer_again each 963this is to configure an <code>ev_timer</code> with <code>after</code>=<code>repeat</code>=<code>60</code> and calling
846time you successfully read or write some data. If you go into an idle 964<code>ev_timer_again</code> each time you successfully read or write some data. If
847state where you do not expect data to travel on the socket, you can stop 965you go into an idle state where you do not expect data to travel on the
848the timer, and again will automatically restart it if need be.</p> 966socket, you can stop the timer, and again will automatically restart it if
967need be.</p>
968 <p>You can also ignore the <code>after</code> value and <code>ev_timer_start</code> altogether
969and only ever use the <code>repeat</code> value:</p>
970<pre> ev_timer_init (timer, callback, 0., 5.);
971 ev_timer_again (loop, timer);
972 ...
973 timer-&gt;again = 17.;
974 ev_timer_again (loop, timer);
975 ...
976 timer-&gt;again = 10.;
977 ev_timer_again (loop, timer);
978
979</pre>
980 <p>This is more efficient then stopping/starting the timer eahc time you want
981to modify its timeout value.</p>
982 </dd>
983 <dt>ev_tstamp repeat [read-write]</dt>
984 <dd>
985 <p>The current <code>repeat</code> value. Will be used each time the watcher times out
986or <code>ev_timer_again</code> is called and determines the next timeout (if any),
987which is also when any modifications are taken into account.</p>
849 </dd> 988 </dd>
850</dl> 989</dl>
851<p>Example: create a timer that fires after 60 seconds.</p> 990<p>Example: Create a timer that fires after 60 seconds.</p>
852<pre> static void 991<pre> static void
853 one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) 992 one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents)
854 { 993 {
855 .. one minute over, w is actually stopped right here 994 .. one minute over, w is actually stopped right here
856 } 995 }
… …
858 struct ev_timer mytimer; 997 struct ev_timer mytimer;
859 ev_timer_init (&amp;mytimer, one_minute_cb, 60., 0.); 998 ev_timer_init (&amp;mytimer, one_minute_cb, 60., 0.);
860 ev_timer_start (loop, &amp;mytimer); 999 ev_timer_start (loop, &amp;mytimer);
861 1000
862</pre> 1001</pre>
863<p>Example: create a timeout timer that times out after 10 seconds of 1002<p>Example: Create a timeout timer that times out after 10 seconds of
864inactivity.</p> 1003inactivity.</p>
865<pre> static void 1004<pre> static void
866 timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents) 1005 timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents)
867 { 1006 {
868 .. ten seconds without any activity 1007 .. ten seconds without any activity
… …
881 1020
882 1021
883</pre> 1022</pre>
884 1023
885</div> 1024</div>
886<h2 id="code_ev_periodic_code_to_cron_or_not"><code>ev_periodic</code> - to cron or not to cron</h2> 1025<h2 id="code_ev_periodic_code_to_cron_or_not"><code>ev_periodic</code> - to cron or not to cron?</h2>
887<div id="code_ev_periodic_code_to_cron_or_not-2"> 1026<div id="code_ev_periodic_code_to_cron_or_not-2">
888<p>Periodic watchers are also timers of a kind, but they are very versatile 1027<p>Periodic watchers are also timers of a kind, but they are very versatile
889(and unfortunately a bit complex).</p> 1028(and unfortunately a bit complex).</p>
890<p>Unlike <code>ev_timer</code>'s, they are not based on real time (or relative time) 1029<p>Unlike <code>ev_timer</code>'s, they are not based on real time (or relative time)
891but on wallclock time (absolute time). You can tell a periodic watcher 1030but on wallclock time (absolute time). You can tell a periodic watcher
… …
971 <p>Simply stops and restarts the periodic watcher again. This is only useful 1110 <p>Simply stops and restarts the periodic watcher again. This is only useful
972when you changed some parameters or the reschedule callback would return 1111when you changed some parameters or the reschedule callback would return
973a different time than the last time it was called (e.g. in a crond like 1112a different time than the last time it was called (e.g. in a crond like
974program when the crontabs have changed).</p> 1113program when the crontabs have changed).</p>
975 </dd> 1114 </dd>
1115 <dt>ev_tstamp interval [read-write]</dt>
1116 <dd>
1117 <p>The current interval value. Can be modified any time, but changes only
1118take effect when the periodic timer fires or <code>ev_periodic_again</code> is being
1119called.</p>
1120 </dd>
1121 <dt>ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read-write]</dt>
1122 <dd>
1123 <p>The current reschedule callback, or <code>0</code>, if this functionality is
1124switched off. Can be changed any time, but changes only take effect when
1125the periodic timer fires or <code>ev_periodic_again</code> is being called.</p>
1126 </dd>
976</dl> 1127</dl>
977<p>Example: call a callback every hour, or, more precisely, whenever the 1128<p>Example: Call a callback every hour, or, more precisely, whenever the
978system clock is divisible by 3600. The callback invocation times have 1129system clock is divisible by 3600. The callback invocation times have
979potentially a lot of jittering, but good long-term stability.</p> 1130potentially a lot of jittering, but good long-term stability.</p>
980<pre> static void 1131<pre> static void
981 clock_cb (struct ev_loop *loop, struct ev_io *w, int revents) 1132 clock_cb (struct ev_loop *loop, struct ev_io *w, int revents)
982 { 1133 {
… …
986 struct ev_periodic hourly_tick; 1137 struct ev_periodic hourly_tick;
987 ev_periodic_init (&amp;hourly_tick, clock_cb, 0., 3600., 0); 1138 ev_periodic_init (&amp;hourly_tick, clock_cb, 0., 3600., 0);
988 ev_periodic_start (loop, &amp;hourly_tick); 1139 ev_periodic_start (loop, &amp;hourly_tick);
989 1140
990</pre> 1141</pre>
991<p>Example: the same as above, but use a reschedule callback to do it:</p> 1142<p>Example: The same as above, but use a reschedule callback to do it:</p>
992<pre> #include &lt;math.h&gt; 1143<pre> #include &lt;math.h&gt;
993 1144
994 static ev_tstamp 1145 static ev_tstamp
995 my_scheduler_cb (struct ev_periodic *w, ev_tstamp now) 1146 my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)
996 { 1147 {
… …
998 } 1149 }
999 1150
1000 ev_periodic_init (&amp;hourly_tick, clock_cb, 0., 0., my_scheduler_cb); 1151 ev_periodic_init (&amp;hourly_tick, clock_cb, 0., 0., my_scheduler_cb);
1001 1152
1002</pre> 1153</pre>
1003<p>Example: call a callback every hour, starting now:</p> 1154<p>Example: Call a callback every hour, starting now:</p>
1004<pre> struct ev_periodic hourly_tick; 1155<pre> struct ev_periodic hourly_tick;
1005 ev_periodic_init (&amp;hourly_tick, clock_cb, 1156 ev_periodic_init (&amp;hourly_tick, clock_cb,
1006 fmod (ev_now (loop), 3600.), 3600., 0); 1157 fmod (ev_now (loop), 3600.), 3600., 0);
1007 ev_periodic_start (loop, &amp;hourly_tick); 1158 ev_periodic_start (loop, &amp;hourly_tick);
1008 1159
… …
1010 1161
1011 1162
1012</pre> 1163</pre>
1013 1164
1014</div> 1165</div>
1015<h2 id="code_ev_signal_code_signal_me_when_a"><code>ev_signal</code> - signal me when a signal gets signalled</h2> 1166<h2 id="code_ev_signal_code_signal_me_when_a"><code>ev_signal</code> - signal me when a signal gets signalled!</h2>
1016<div id="code_ev_signal_code_signal_me_when_a-2"> 1167<div id="code_ev_signal_code_signal_me_when_a-2">
1017<p>Signal watchers will trigger an event when the process receives a specific 1168<p>Signal watchers will trigger an event when the process receives a specific
1018signal one or more times. Even though signals are very asynchronous, libev 1169signal one or more times. Even though signals are very asynchronous, libev
1019will try it's best to deliver signals synchronously, i.e. as part of the 1170will try it's best to deliver signals synchronously, i.e. as part of the
1020normal event processing, like any other event.</p> 1171normal event processing, like any other event.</p>
… …
1029 <dt>ev_signal_set (ev_signal *, int signum)</dt> 1180 <dt>ev_signal_set (ev_signal *, int signum)</dt>
1030 <dd> 1181 <dd>
1031 <p>Configures the watcher to trigger on the given signal number (usually one 1182 <p>Configures the watcher to trigger on the given signal number (usually one
1032of the <code>SIGxxx</code> constants).</p> 1183of the <code>SIGxxx</code> constants).</p>
1033 </dd> 1184 </dd>
1185 <dt>int signum [read-only]</dt>
1186 <dd>
1187 <p>The signal the watcher watches out for.</p>
1188 </dd>
1034</dl> 1189</dl>
1035 1190
1036 1191
1037 1192
1038 1193
1039 1194
1040</div> 1195</div>
1041<h2 id="code_ev_child_code_wait_for_pid_stat"><code>ev_child</code> - wait for pid status changes</h2> 1196<h2 id="code_ev_child_code_watch_out_for_pro"><code>ev_child</code> - watch out for process status changes</h2>
1042<div id="code_ev_child_code_wait_for_pid_stat-2"> 1197<div id="code_ev_child_code_watch_out_for_pro-2">
1043<p>Child watchers trigger when your process receives a SIGCHLD in response to 1198<p>Child watchers trigger when your process receives a SIGCHLD in response to
1044some child status changes (most typically when a child of yours dies).</p> 1199some child status changes (most typically when a child of yours dies).</p>
1045<dl> 1200<dl>
1046 <dt>ev_child_init (ev_child *, callback, int pid)</dt> 1201 <dt>ev_child_init (ev_child *, callback, int pid)</dt>
1047 <dt>ev_child_set (ev_child *, int pid)</dt> 1202 <dt>ev_child_set (ev_child *, int pid)</dt>
… …
1051at the <code>rstatus</code> member of the <code>ev_child</code> watcher structure to see 1206at the <code>rstatus</code> member of the <code>ev_child</code> watcher structure to see
1052the status word (use the macros from <code>sys/wait.h</code> and see your systems 1207the status word (use the macros from <code>sys/wait.h</code> and see your systems
1053<code>waitpid</code> documentation). The <code>rpid</code> member contains the pid of the 1208<code>waitpid</code> documentation). The <code>rpid</code> member contains the pid of the
1054process causing the status change.</p> 1209process causing the status change.</p>
1055 </dd> 1210 </dd>
1211 <dt>int pid [read-only]</dt>
1212 <dd>
1213 <p>The process id this watcher watches out for, or <code>0</code>, meaning any process id.</p>
1214 </dd>
1215 <dt>int rpid [read-write]</dt>
1216 <dd>
1217 <p>The process id that detected a status change.</p>
1218 </dd>
1219 <dt>int rstatus [read-write]</dt>
1220 <dd>
1221 <p>The process exit/trace status caused by <code>rpid</code> (see your systems
1222<code>waitpid</code> and <code>sys/wait.h</code> documentation for details).</p>
1223 </dd>
1056</dl> 1224</dl>
1057<p>Example: try to exit cleanly on SIGINT and SIGTERM.</p> 1225<p>Example: Try to exit cleanly on SIGINT and SIGTERM.</p>
1058<pre> static void 1226<pre> static void
1059 sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) 1227 sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents)
1060 { 1228 {
1061 ev_unloop (loop, EVUNLOOP_ALL); 1229 ev_unloop (loop, EVUNLOOP_ALL);
1062 } 1230 }
… …
1069 1237
1070 1238
1071</pre> 1239</pre>
1072 1240
1073</div> 1241</div>
1242<h2 id="code_ev_stat_code_did_the_file_attri"><code>ev_stat</code> - did the file attributes just change?</h2>
1243<div id="code_ev_stat_code_did_the_file_attri-2">
1244<p>This watches a filesystem path for attribute changes. That is, it calls
1245<code>stat</code> regularly (or when the OS says it changed) and sees if it changed
1246compared to the last time, invoking the callback if it did.</p>
1247<p>The path does not need to exist: changing from &quot;path exists&quot; to &quot;path does
1248not exist&quot; is a status change like any other. The condition &quot;path does
1249not exist&quot; is signified by the <code>st_nlink</code> field being zero (which is
1250otherwise always forced to be at least one) and all the other fields of
1251the stat buffer having unspecified contents.</p>
1252<p>Since there is no standard to do this, the portable implementation simply
1253calls <code>stat (2)</code> regularly on the path to see if it changed somehow. You
1254can specify a recommended polling interval for this case. If you specify
1255a polling interval of <code>0</code> (highly recommended!) then a <i>suitable,
1256unspecified default</i> value will be used (which you can expect to be around
1257five seconds, although this might change dynamically). Libev will also
1258impose a minimum interval which is currently around <code>0.1</code>, but thats
1259usually overkill.</p>
1260<p>This watcher type is not meant for massive numbers of stat watchers,
1261as even with OS-supported change notifications, this can be
1262resource-intensive.</p>
1263<p>At the time of this writing, only the Linux inotify interface is
1264implemented (implementing kqueue support is left as an exercise for the
1265reader). Inotify will be used to give hints only and should not change the
1266semantics of <code>ev_stat</code> watchers, which means that libev sometimes needs
1267to fall back to regular polling again even with inotify, but changes are
1268usually detected immediately, and if the file exists there will be no
1269polling.</p>
1270<dl>
1271 <dt>ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)</dt>
1272 <dt>ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)</dt>
1273 <dd>
1274 <p>Configures the watcher to wait for status changes of the given
1275<code>path</code>. The <code>interval</code> is a hint on how quickly a change is expected to
1276be detected and should normally be specified as <code>0</code> to let libev choose
1277a suitable value. The memory pointed to by <code>path</code> must point to the same
1278path for as long as the watcher is active.</p>
1279 <p>The callback will be receive <code>EV_STAT</code> when a change was detected,
1280relative to the attributes at the time the watcher was started (or the
1281last change was detected).</p>
1282 </dd>
1283 <dt>ev_stat_stat (ev_stat *)</dt>
1284 <dd>
1285 <p>Updates the stat buffer immediately with new values. If you change the
1286watched path in your callback, you could call this fucntion to avoid
1287detecting this change (while introducing a race condition). Can also be
1288useful simply to find out the new values.</p>
1289 </dd>
1290 <dt>ev_statdata attr [read-only]</dt>
1291 <dd>
1292 <p>The most-recently detected attributes of the file. Although the type is of
1293<code>ev_statdata</code>, this is usually the (or one of the) <code>struct stat</code> types
1294suitable for your system. If the <code>st_nlink</code> member is <code>0</code>, then there
1295was some error while <code>stat</code>ing the file.</p>
1296 </dd>
1297 <dt>ev_statdata prev [read-only]</dt>
1298 <dd>
1299 <p>The previous attributes of the file. The callback gets invoked whenever
1300<code>prev</code> != <code>attr</code>.</p>
1301 </dd>
1302 <dt>ev_tstamp interval [read-only]</dt>
1303 <dd>
1304 <p>The specified interval.</p>
1305 </dd>
1306 <dt>const char *path [read-only]</dt>
1307 <dd>
1308 <p>The filesystem path that is being watched.</p>
1309 </dd>
1310</dl>
1311<p>Example: Watch <code>/etc/passwd</code> for attribute changes.</p>
1312<pre> static void
1313 passwd_cb (struct ev_loop *loop, ev_stat *w, int revents)
1314 {
1315 /* /etc/passwd changed in some way */
1316 if (w-&gt;attr.st_nlink)
1317 {
1318 printf (&quot;passwd current size %ld\n&quot;, (long)w-&gt;attr.st_size);
1319 printf (&quot;passwd current atime %ld\n&quot;, (long)w-&gt;attr.st_mtime);
1320 printf (&quot;passwd current mtime %ld\n&quot;, (long)w-&gt;attr.st_mtime);
1321 }
1322 else
1323 /* you shalt not abuse printf for puts */
1324 puts (&quot;wow, /etc/passwd is not there, expect problems. &quot;
1325 &quot;if this is windows, they already arrived\n&quot;);
1326 }
1327
1328 ...
1329 ev_stat passwd;
1330
1331 ev_stat_init (&amp;passwd, passwd_cb, &quot;/etc/passwd&quot;);
1332 ev_stat_start (loop, &amp;passwd);
1333
1334
1335
1336
1337</pre>
1338
1339</div>
1074<h2 id="code_ev_idle_code_when_you_ve_got_no"><code>ev_idle</code> - when you've got nothing better to do</h2> 1340<h2 id="code_ev_idle_code_when_you_ve_got_no"><code>ev_idle</code> - when you've got nothing better to do...</h2>
1075<div id="code_ev_idle_code_when_you_ve_got_no-2"> 1341<div id="code_ev_idle_code_when_you_ve_got_no-2">
1076<p>Idle watchers trigger events when there are no other events are pending 1342<p>Idle watchers trigger events when there are no other events are pending
1077(prepare, check and other idle watchers do not count). That is, as long 1343(prepare, check and other idle watchers do not count). That is, as long
1078as your process is busy handling sockets or timeouts (or even signals, 1344as your process is busy handling sockets or timeouts (or even signals,
1079imagine) it will not be triggered. But when your process is idle all idle 1345imagine) it will not be triggered. But when your process is idle all idle
… …
1092 <p>Initialises and configures the idle watcher - it has no parameters of any 1358 <p>Initialises and configures the idle watcher - it has no parameters of any
1093kind. There is a <code>ev_idle_set</code> macro, but using it is utterly pointless, 1359kind. There is a <code>ev_idle_set</code> macro, but using it is utterly pointless,
1094believe me.</p> 1360believe me.</p>
1095 </dd> 1361 </dd>
1096</dl> 1362</dl>
1097<p>Example: dynamically allocate an <code>ev_idle</code>, start it, and in the 1363<p>Example: Dynamically allocate an <code>ev_idle</code> watcher, start it, and in the
1098callback, free it. Alos, use no error checking, as usual.</p> 1364callback, free it. Also, use no error checking, as usual.</p>
1099<pre> static void 1365<pre> static void
1100 idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents) 1366 idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents)
1101 { 1367 {
1102 free (w); 1368 free (w);
1103 // now do something you wanted to do when the program has 1369 // now do something you wanted to do when the program has
… …
1112 1378
1113 1379
1114</pre> 1380</pre>
1115 1381
1116</div> 1382</div>
1117<h2 id="code_ev_prepare_code_and_code_ev_che"><code>ev_prepare</code> and <code>ev_check</code> - customise your event loop</h2> 1383<h2 id="code_ev_prepare_code_and_code_ev_che"><code>ev_prepare</code> and <code>ev_check</code> - customise your event loop!</h2>
1118<div id="code_ev_prepare_code_and_code_ev_che-2"> 1384<div id="code_ev_prepare_code_and_code_ev_che-2">
1119<p>Prepare and check watchers are usually (but not always) used in tandem: 1385<p>Prepare and check watchers are usually (but not always) used in tandem:
1120prepare watchers get invoked before the process blocks and check watchers 1386prepare watchers get invoked before the process blocks and check watchers
1121afterwards.</p> 1387afterwards.</p>
1388<p>You <i>must not</i> call <code>ev_loop</code> or similar functions that enter
1389the current event loop from either <code>ev_prepare</code> or <code>ev_check</code>
1390watchers. Other loops than the current one are fine, however. The
1391rationale behind this is that you do not need to check for recursion in
1392those watchers, i.e. the sequence will always be <code>ev_prepare</code>, blocking,
1393<code>ev_check</code> so if you have one watcher of each kind they will always be
1394called in pairs bracketing the blocking call.</p>
1122<p>Their main purpose is to integrate other event mechanisms into libev and 1395<p>Their main purpose is to integrate other event mechanisms into libev and
1123their use is somewhat advanced. This could be used, for example, to track 1396their use is somewhat advanced. This could be used, for example, to track
1124variable changes, implement your own watchers, integrate net-snmp or a 1397variable changes, implement your own watchers, integrate net-snmp or a
1125coroutine library and lots more.</p> 1398coroutine library and lots more. They are also occasionally useful if
1399you cache some data and want to flush it before blocking (for example,
1400in X programs you might want to do an <code>XFlush ()</code> in an <code>ev_prepare</code>
1401watcher).</p>
1126<p>This is done by examining in each prepare call which file descriptors need 1402<p>This is done by examining in each prepare call which file descriptors need
1127to be watched by the other library, registering <code>ev_io</code> watchers for 1403to be watched by the other library, registering <code>ev_io</code> watchers for
1128them and starting an <code>ev_timer</code> watcher for any timeouts (many libraries 1404them and starting an <code>ev_timer</code> watcher for any timeouts (many libraries
1129provide just this functionality). Then, in the check watcher you check for 1405provide just this functionality). Then, in the check watcher you check for
1130any events that occured (by checking the pending status of all watchers 1406any events that occured (by checking the pending status of all watchers
… …
1146 <p>Initialises and configures the prepare or check watcher - they have no 1422 <p>Initialises and configures the prepare or check watcher - they have no
1147parameters of any kind. There are <code>ev_prepare_set</code> and <code>ev_check_set</code> 1423parameters of any kind. There are <code>ev_prepare_set</code> and <code>ev_check_set</code>
1148macros, but using them is utterly, utterly and completely pointless.</p> 1424macros, but using them is utterly, utterly and completely pointless.</p>
1149 </dd> 1425 </dd>
1150</dl> 1426</dl>
1151<p>Example: *TODO*.</p> 1427<p>Example: To include a library such as adns, you would add IO watchers
1428and a timeout watcher in a prepare handler, as required by libadns, and
1429in a check watcher, destroy them and call into libadns. What follows is
1430pseudo-code only of course:</p>
1431<pre> static ev_io iow [nfd];
1432 static ev_timer tw;
1152 1433
1434 static void
1435 io_cb (ev_loop *loop, ev_io *w, int revents)
1436 {
1437 // set the relevant poll flags
1438 // could also call adns_processreadable etc. here
1439 struct pollfd *fd = (struct pollfd *)w-&gt;data;
1440 if (revents &amp; EV_READ ) fd-&gt;revents |= fd-&gt;events &amp; POLLIN;
1441 if (revents &amp; EV_WRITE) fd-&gt;revents |= fd-&gt;events &amp; POLLOUT;
1442 }
1153 1443
1444 // create io watchers for each fd and a timer before blocking
1445 static void
1446 adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents)
1447 {
1448 int timeout = 3600000;truct pollfd fds [nfd];
1449 // actual code will need to loop here and realloc etc.
1450 adns_beforepoll (ads, fds, &amp;nfd, &amp;timeout, timeval_from (ev_time ()));
1154 1451
1452 /* the callback is illegal, but won't be called as we stop during check */
1453 ev_timer_init (&amp;tw, 0, timeout * 1e-3);
1454 ev_timer_start (loop, &amp;tw);
1155 1455
1456 // create on ev_io per pollfd
1457 for (int i = 0; i &lt; nfd; ++i)
1458 {
1459 ev_io_init (iow + i, io_cb, fds [i].fd,
1460 ((fds [i].events &amp; POLLIN ? EV_READ : 0)
1461 | (fds [i].events &amp; POLLOUT ? EV_WRITE : 0)));
1156 1462
1463 fds [i].revents = 0;
1464 iow [i].data = fds + i;
1465 ev_io_start (loop, iow + i);
1466 }
1467 }
1468
1469 // stop all watchers after blocking
1470 static void
1471 adns_check_cb (ev_loop *loop, ev_check *w, int revents)
1472 {
1473 ev_timer_stop (loop, &amp;tw);
1474
1475 for (int i = 0; i &lt; nfd; ++i)
1476 ev_io_stop (loop, iow + i);
1477
1478 adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));
1479 }
1480
1481
1482
1483
1484</pre>
1485
1157</div> 1486</div>
1158<h2 id="code_ev_embed_code_when_one_backend_"><code>ev_embed</code> - when one backend isn't enough</h2> 1487<h2 id="code_ev_embed_code_when_one_backend_"><code>ev_embed</code> - when one backend isn't enough...</h2>
1159<div id="code_ev_embed_code_when_one_backend_-2"> 1488<div id="code_ev_embed_code_when_one_backend_-2">
1160<p>This is a rather advanced watcher type that lets you embed one event loop 1489<p>This is a rather advanced watcher type that lets you embed one event loop
1161into another (currently only <code>ev_io</code> events are supported in the embedded 1490into another (currently only <code>ev_io</code> events are supported in the embedded
1162loop, other types of watchers might be handled in a delayed or incorrect 1491loop, other types of watchers might be handled in a delayed or incorrect
1163fashion and must not be used).</p> 1492fashion and must not be used).</p>
… …
1231 <dd> 1560 <dd>
1232 <p>Make a single, non-blocking sweep over the embedded loop. This works 1561 <p>Make a single, non-blocking sweep over the embedded loop. This works
1233similarly to <code>ev_loop (embedded_loop, EVLOOP_NONBLOCK)</code>, but in the most 1562similarly to <code>ev_loop (embedded_loop, EVLOOP_NONBLOCK)</code>, but in the most
1234apropriate way for embedded loops.</p> 1563apropriate way for embedded loops.</p>
1235 </dd> 1564 </dd>
1565 <dt>struct ev_loop *loop [read-only]</dt>
1566 <dd>
1567 <p>The embedded event loop.</p>
1568 </dd>
1236</dl> 1569</dl>
1237 1570
1238 1571
1239 1572
1240 1573
1241 1574
1242</div> 1575</div>
1243<h1 id="OTHER_FUNCTIONS">OTHER FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p> 1576<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>
1577<div id="code_ev_fork_code_the_audacity_to_re-2">
1578<p>Fork watchers are called when a <code>fork ()</code> was detected (usually because
1579whoever is a good citizen cared to tell libev about it by calling
1580<code>ev_default_fork</code> or <code>ev_loop_fork</code>). The invocation is done before the
1581event loop blocks next and before <code>ev_check</code> watchers are being called,
1582and only in the child after the fork. If whoever good citizen calling
1583<code>ev_default_fork</code> cheats and calls it in the wrong process, the fork
1584handlers will be invoked, too, of course.</p>
1585<dl>
1586 <dt>ev_fork_init (ev_signal *, callback)</dt>
1587 <dd>
1588 <p>Initialises and configures the fork watcher - it has no parameters of any
1589kind. There is a <code>ev_fork_set</code> macro, but using it is utterly pointless,
1590believe me.</p>
1591 </dd>
1592</dl>
1593
1594
1595
1596
1597
1598</div>
1599<h1 id="OTHER_FUNCTIONS">OTHER FUNCTIONS</h1>
1244<div id="OTHER_FUNCTIONS_CONTENT"> 1600<div id="OTHER_FUNCTIONS_CONTENT">
1245<p>There are some other functions of possible interest. Described. Here. Now.</p> 1601<p>There are some other functions of possible interest. Described. Here. Now.</p>
1246<dl> 1602<dl>
1247 <dt>ev_once (loop, int fd, int events, ev_tstamp timeout, callback)</dt> 1603 <dt>ev_once (loop, int fd, int events, ev_tstamp timeout, callback)</dt>
1248 <dd> 1604 <dd>
… …
1295 1651
1296 1652
1297 1653
1298 1654
1299</div> 1655</div>
1300<h1 id="LIBEVENT_EMULATION">LIBEVENT EMULATION</h1><p><a href="#TOP" class="toplink">Top</a></p> 1656<h1 id="LIBEVENT_EMULATION">LIBEVENT EMULATION</h1>
1301<div id="LIBEVENT_EMULATION_CONTENT"> 1657<div id="LIBEVENT_EMULATION_CONTENT">
1302<p>Libev offers a compatibility emulation layer for libevent. It cannot 1658<p>Libev offers a compatibility emulation layer for libevent. It cannot
1303emulate the internals of libevent, so here are some usage hints:</p> 1659emulate the internals of libevent, so here are some usage hints:</p>
1304<dl> 1660<dl>
1305 <dt>* Use it by including &lt;event.h&gt;, as usual.</dt> 1661 <dt>* Use it by including &lt;event.h&gt;, as usual.</dt>
… …
1315 <dt>* The libev emulation is <i>not</i> ABI compatible to libevent, you need 1671 <dt>* The libev emulation is <i>not</i> ABI compatible to libevent, you need
1316to use the libev header file and library.</dt> 1672to use the libev header file and library.</dt>
1317</dl> 1673</dl>
1318 1674
1319</div> 1675</div>
1320<h1 id="C_SUPPORT">C++ SUPPORT</h1><p><a href="#TOP" class="toplink">Top</a></p> 1676<h1 id="C_SUPPORT">C++ SUPPORT</h1>
1321<div id="C_SUPPORT_CONTENT"> 1677<div id="C_SUPPORT_CONTENT">
1322<p>Libev comes with some simplistic wrapper classes for C++ that mainly allow 1678<p>Libev comes with some simplistic wrapper classes for C++ that mainly allow
1323you to use some convinience methods to start/stop watchers and also change 1679you to use some convinience methods to start/stop watchers and also change
1324the callback model to a model using method callbacks on objects.</p> 1680the callback model to a model using method callbacks on objects.</p>
1325<p>To use it,</p> 1681<p>To use it,</p>
… …
1389 </dd> 1745 </dd>
1390 <dt>w-&gt;sweep () <code>ev::embed</code> only</dt> 1746 <dt>w-&gt;sweep () <code>ev::embed</code> only</dt>
1391 <dd> 1747 <dd>
1392 <p>Invokes <code>ev_embed_sweep</code>.</p> 1748 <p>Invokes <code>ev_embed_sweep</code>.</p>
1393 </dd> 1749 </dd>
1750 <dt>w-&gt;update () <code>ev::stat</code> only</dt>
1751 <dd>
1752 <p>Invokes <code>ev_stat_stat</code>.</p>
1753 </dd>
1394 </dl> 1754 </dl>
1395 </p> 1755 </p>
1396 </dd> 1756 </dd>
1397</dl> 1757</dl>
1398<p>Example: Define a class with an IO and idle watcher, start one of them in 1758<p>Example: Define a class with an IO and idle watcher, start one of them in
… …
1410 idle (this, &amp;myclass::idle_cb) 1770 idle (this, &amp;myclass::idle_cb)
1411 { 1771 {
1412 io.start (fd, ev::READ); 1772 io.start (fd, ev::READ);
1413 } 1773 }
1414 1774
1415</pre>
1416 1775
1776
1777
1778</pre>
1779
1417</div> 1780</div>
1418<h1 id="EMBEDDING">EMBEDDING</h1><p><a href="#TOP" class="toplink">Top</a></p> 1781<h1 id="MACRO_MAGIC">MACRO MAGIC</h1>
1782<div id="MACRO_MAGIC_CONTENT">
1783<p>Libev can be compiled with a variety of options, the most fundemantal is
1784<code>EV_MULTIPLICITY</code>. This option determines wether (most) functions and
1785callbacks have an initial <code>struct ev_loop *</code> argument.</p>
1786<p>To make it easier to write programs that cope with either variant, the
1787following macros are defined:</p>
1788<dl>
1789 <dt><code>EV_A</code>, <code>EV_A_</code></dt>
1790 <dd>
1791 <p>This provides the loop <i>argument</i> for functions, if one is required (&quot;ev
1792loop argument&quot;). The <code>EV_A</code> form is used when this is the sole argument,
1793<code>EV_A_</code> is used when other arguments are following. Example:</p>
1794<pre> ev_unref (EV_A);
1795 ev_timer_add (EV_A_ watcher);
1796 ev_loop (EV_A_ 0);
1797
1798</pre>
1799 <p>It assumes the variable <code>loop</code> of type <code>struct ev_loop *</code> is in scope,
1800which is often provided by the following macro.</p>
1801 </dd>
1802 <dt><code>EV_P</code>, <code>EV_P_</code></dt>
1803 <dd>
1804 <p>This provides the loop <i>parameter</i> for functions, if one is required (&quot;ev
1805loop parameter&quot;). The <code>EV_P</code> form is used when this is the sole parameter,
1806<code>EV_P_</code> is used when other parameters are following. Example:</p>
1807<pre> // this is how ev_unref is being declared
1808 static void ev_unref (EV_P);
1809
1810 // this is how you can declare your typical callback
1811 static void cb (EV_P_ ev_timer *w, int revents)
1812
1813</pre>
1814 <p>It declares a parameter <code>loop</code> of type <code>struct ev_loop *</code>, quite
1815suitable for use with <code>EV_A</code>.</p>
1816 </dd>
1817 <dt><code>EV_DEFAULT</code>, <code>EV_DEFAULT_</code></dt>
1818 <dd>
1819 <p>Similar to the other two macros, this gives you the value of the default
1820loop, if multiple loops are supported (&quot;ev loop default&quot;).</p>
1821 </dd>
1822</dl>
1823<p>Example: Declare and initialise a check watcher, working regardless of
1824wether multiple loops are supported or not.</p>
1825<pre> static void
1826 check_cb (EV_P_ ev_timer *w, int revents)
1827 {
1828 ev_check_stop (EV_A_ w);
1829 }
1830
1831 ev_check check;
1832 ev_check_init (&amp;check, check_cb);
1833 ev_check_start (EV_DEFAULT_ &amp;check);
1834 ev_loop (EV_DEFAULT_ 0);
1835
1836
1837
1838
1839</pre>
1840
1841</div>
1842<h1 id="EMBEDDING">EMBEDDING</h1>
1419<div id="EMBEDDING_CONTENT"> 1843<div id="EMBEDDING_CONTENT">
1420<p>Libev can (and often is) directly embedded into host 1844<p>Libev can (and often is) directly embedded into host
1421applications. Examples of applications that embed it include the Deliantra 1845applications. Examples of applications that embed it include the Deliantra
1422Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe) 1846Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe)
1423and rxvt-unicode.</p> 1847and rxvt-unicode.</p>
… …
1460 ev_vars.h 1884 ev_vars.h
1461 ev_wrap.h 1885 ev_wrap.h
1462 1886
1463 ev_win32.c required on win32 platforms only 1887 ev_win32.c required on win32 platforms only
1464 1888
1465 ev_select.c only when select backend is enabled (which is is by default) 1889 ev_select.c only when select backend is enabled (which is by default)
1466 ev_poll.c only when poll backend is enabled (disabled by default) 1890 ev_poll.c only when poll backend is enabled (disabled by default)
1467 ev_epoll.c only when the epoll backend is enabled (disabled by default) 1891 ev_epoll.c only when the epoll backend is enabled (disabled by default)
1468 ev_kqueue.c only when the kqueue backend is enabled (disabled by default) 1892 ev_kqueue.c only when the kqueue backend is enabled (disabled by default)
1469 ev_port.c only when the solaris port backend is enabled (disabled by default) 1893 ev_port.c only when the solaris port backend is enabled (disabled by default)
1470 1894
1471</pre> 1895</pre>
1472<p><cite>ev.c</cite> includes the backend files directly when enabled, so you only need 1896<p><cite>ev.c</cite> includes the backend files directly when enabled, so you only need
1473to compile a single file.</p> 1897to compile this single file.</p>
1474 1898
1475</div> 1899</div>
1476<h3 id="LIBEVENT_COMPATIBILITY_API">LIBEVENT COMPATIBILITY API</h3> 1900<h3 id="LIBEVENT_COMPATIBILITY_API">LIBEVENT COMPATIBILITY API</h3>
1477<div id="LIBEVENT_COMPATIBILITY_API_CONTENT"> 1901<div id="LIBEVENT_COMPATIBILITY_API_CONTENT">
1478<p>To include the libevent compatibility API, also include:</p> 1902<p>To include the libevent compatibility API, also include:</p>
… …
1493</div> 1917</div>
1494<h3 id="AUTOCONF_SUPPORT">AUTOCONF SUPPORT</h3> 1918<h3 id="AUTOCONF_SUPPORT">AUTOCONF SUPPORT</h3>
1495<div id="AUTOCONF_SUPPORT_CONTENT"> 1919<div id="AUTOCONF_SUPPORT_CONTENT">
1496<p>Instead of using <code>EV_STANDALONE=1</code> and providing your config in 1920<p>Instead of using <code>EV_STANDALONE=1</code> and providing your config in
1497whatever way you want, you can also <code>m4_include([libev.m4])</code> in your 1921whatever way you want, you can also <code>m4_include([libev.m4])</code> in your
1498<cite>configure.ac</cite> and leave <code>EV_STANDALONE</code> off. <cite>ev.c</cite> will then include 1922<cite>configure.ac</cite> and leave <code>EV_STANDALONE</code> undefined. <cite>ev.c</cite> will then
1499<cite>config.h</cite> and configure itself accordingly.</p> 1923include <cite>config.h</cite> and configure itself accordingly.</p>
1500<p>For this of course you need the m4 file:</p> 1924<p>For this of course you need the m4 file:</p>
1501<pre> libev.m4 1925<pre> libev.m4
1502 1926
1503</pre> 1927</pre>
1504 1928
… …
1583otherwise another method will be used as fallback. This is the preferred 2007otherwise another method will be used as fallback. This is the preferred
1584backend for BSD and BSD-like systems, although on most BSDs kqueue only 2008backend for BSD and BSD-like systems, although on most BSDs kqueue only
1585supports some types of fds correctly (the only platform we found that 2009supports some types of fds correctly (the only platform we found that
1586supports ptys for example was NetBSD), so kqueue might be compiled in, but 2010supports ptys for example was NetBSD), so kqueue might be compiled in, but
1587not be used unless explicitly requested. The best way to use it is to find 2011not be used unless explicitly requested. The best way to use it is to find
1588out wether kqueue supports your type of fd properly and use an embedded 2012out whether kqueue supports your type of fd properly and use an embedded
1589kqueue loop.</p> 2013kqueue loop.</p>
1590 </dd> 2014 </dd>
1591 <dt>EV_USE_PORT</dt> 2015 <dt>EV_USE_PORT</dt>
1592 <dd> 2016 <dd>
1593 <p>If defined to be <code>1</code>, libev will compile in support for the Solaris 2017 <p>If defined to be <code>1</code>, libev will compile in support for the Solaris
… …
1596backend for Solaris 10 systems.</p> 2020backend for Solaris 10 systems.</p>
1597 </dd> 2021 </dd>
1598 <dt>EV_USE_DEVPOLL</dt> 2022 <dt>EV_USE_DEVPOLL</dt>
1599 <dd> 2023 <dd>
1600 <p>reserved for future expansion, works like the USE symbols above.</p> 2024 <p>reserved for future expansion, works like the USE symbols above.</p>
2025 </dd>
2026 <dt>EV_USE_INOTIFY</dt>
2027 <dd>
2028 <p>If defined to be <code>1</code>, libev will compile in support for the Linux inotify
2029interface to speed up <code>ev_stat</code> watchers. Its actual availability will
2030be detected at runtime.</p>
1601 </dd> 2031 </dd>
1602 <dt>EV_H</dt> 2032 <dt>EV_H</dt>
1603 <dd> 2033 <dd>
1604 <p>The name of the <cite>ev.h</cite> header file used to include it. The default if 2034 <p>The name of the <cite>ev.h</cite> header file used to include it. The default if
1605undefined 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 2035undefined 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
… …
1629will have the <code>struct ev_loop *</code> as first argument, and you can create 2059will have the <code>struct ev_loop *</code> as first argument, and you can create
1630additional independent event loops. Otherwise there will be no support 2060additional independent event loops. Otherwise there will be no support
1631for multiple event loops and there is no first event loop pointer 2061for multiple event loops and there is no first event loop pointer
1632argument. Instead, all functions act on the single default loop.</p> 2062argument. Instead, all functions act on the single default loop.</p>
1633 </dd> 2063 </dd>
1634 <dt>EV_PERIODICS</dt> 2064 <dt>EV_PERIODIC_ENABLE</dt>
1635 <dd> 2065 <dd>
1636 <p>If undefined or defined to be <code>1</code>, then periodic timers are supported, 2066 <p>If undefined or defined to be <code>1</code>, then periodic timers are supported. If
1637otherwise not. This saves a few kb of code.</p> 2067defined to be <code>0</code>, then they are not. Disabling them saves a few kB of
2068code.</p>
2069 </dd>
2070 <dt>EV_EMBED_ENABLE</dt>
2071 <dd>
2072 <p>If undefined or defined to be <code>1</code>, then embed watchers are supported. If
2073defined to be <code>0</code>, then they are not.</p>
2074 </dd>
2075 <dt>EV_STAT_ENABLE</dt>
2076 <dd>
2077 <p>If undefined or defined to be <code>1</code>, then stat watchers are supported. If
2078defined to be <code>0</code>, then they are not.</p>
2079 </dd>
2080 <dt>EV_FORK_ENABLE</dt>
2081 <dd>
2082 <p>If undefined or defined to be <code>1</code>, then fork watchers are supported. If
2083defined to be <code>0</code>, then they are not.</p>
2084 </dd>
2085 <dt>EV_MINIMAL</dt>
2086 <dd>
2087 <p>If you need to shave off some kilobytes of code at the expense of some
2088speed, define this symbol to <code>1</code>. Currently only used for gcc to override
2089some inlining decisions, saves roughly 30% codesize of amd64.</p>
2090 </dd>
2091 <dt>EV_PID_HASHSIZE</dt>
2092 <dd>
2093 <p><code>ev_child</code> watchers use a small hash table to distribute workload by
2094pid. The default size is <code>16</code> (or <code>1</code> with <code>EV_MINIMAL</code>), usually more
2095than enough. If you need to manage thousands of children you might want to
2096increase this value (<i>must</i> be a power of two).</p>
2097 </dd>
2098 <dt>EV_INOTIFY_HASHSIZE</dt>
2099 <dd>
2100 <p><code>ev_staz</code> watchers use a small hash table to distribute workload by
2101inotify watch id. The default size is <code>16</code> (or <code>1</code> with <code>EV_MINIMAL</code>),
2102usually more than enough. If you need to manage thousands of <code>ev_stat</code>
2103watchers you might want to increase this value (<i>must</i> be a power of
2104two).</p>
1638 </dd> 2105 </dd>
1639 <dt>EV_COMMON</dt> 2106 <dt>EV_COMMON</dt>
1640 <dd> 2107 <dd>
1641 <p>By default, all watchers have a <code>void *data</code> member. By redefining 2108 <p>By default, all watchers have a <code>void *data</code> member. By redefining
1642this macro to a something else you can include more and other types of 2109this macro to a something else you can include more and other types of
… …
1647 SV *self; /* contains this struct */ \ 2114 SV *self; /* contains this struct */ \
1648 SV *cb_sv, *fh /* note no trailing &quot;;&quot; */ 2115 SV *cb_sv, *fh /* note no trailing &quot;;&quot; */
1649 2116
1650</pre> 2117</pre>
1651 </dd> 2118 </dd>
1652 <dt>EV_CB_DECLARE(type)</dt> 2119 <dt>EV_CB_DECLARE (type)</dt>
1653 <dt>EV_CB_INVOKE(watcher,revents)</dt> 2120 <dt>EV_CB_INVOKE (watcher, revents)</dt>
1654 <dt>ev_set_cb(ev,cb)</dt> 2121 <dt>ev_set_cb (ev, cb)</dt>
1655 <dd> 2122 <dd>
1656 <p>Can be used to change the callback member declaration in each watcher, 2123 <p>Can be used to change the callback member declaration in each watcher,
1657and the way callbacks are invoked and set. Must expand to a struct member 2124and the way callbacks are invoked and set. Must expand to a struct member
1658definition and a statement, respectively. See the <cite>ev.v</cite> header file for 2125definition and a statement, respectively. See the <cite>ev.v</cite> header file for
1659their default definitions. One possible use for overriding these is to 2126their default definitions. One possible use for overriding these is to
1660avoid the ev_loop pointer as first argument in all cases, or to use method 2127avoid the <code>struct ev_loop *</code> as first argument in all cases, or to use
1661calls instead of plain function calls in C++.</p> 2128method calls instead of plain function calls in C++.</p>
1662 2129
1663</div> 2130</div>
1664<h2 id="EXAMPLES">EXAMPLES</h2> 2131<h2 id="EXAMPLES">EXAMPLES</h2>
1665<div id="EXAMPLES_CONTENT"> 2132<div id="EXAMPLES_CONTENT">
1666 <p>For a real-world example of a program the includes libev 2133 <p>For a real-world example of a program the includes libev
… …
1682</pre> 2149</pre>
1683 <p>And a <cite>ev_cpp.C</cite> implementation file that contains libev proper and is compiled:</p> 2150 <p>And a <cite>ev_cpp.C</cite> implementation file that contains libev proper and is compiled:</p>
1684<pre> #include &quot;ev_cpp.h&quot; 2151<pre> #include &quot;ev_cpp.h&quot;
1685 #include &quot;ev.c&quot; 2152 #include &quot;ev.c&quot;
1686 2153
1687</pre>
1688 2154
2155
2156
2157</pre>
2158
1689</div> 2159</div>
1690<h1 id="AUTHOR">AUTHOR</h1><p><a href="#TOP" class="toplink">Top</a></p> 2160<h1 id="COMPLEXITIES">COMPLEXITIES</h1>
2161<div id="COMPLEXITIES_CONTENT">
2162 <p>In this section the complexities of (many of) the algorithms used inside
2163libev will be explained. For complexity discussions about backends see the
2164documentation for <code>ev_default_init</code>.</p>
2165 <p>
2166 <dl>
2167 <dt>Starting and stopping timer/periodic watchers: O(log skipped_other_timers)</dt>
2168 <dt>Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)</dt>
2169 <dt>Starting io/check/prepare/idle/signal/child watchers: O(1)</dt>
2170 <dt>Stopping check/prepare/idle watchers: O(1)</dt>
2171 <dt>Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))</dt>
2172 <dt>Finding the next timer per loop iteration: O(1)</dt>
2173 <dt>Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)</dt>
2174 <dt>Activating one watcher: O(1)</dt>
2175 </dl>
2176 </p>
2177
2178
2179
2180
2181
2182</div>
2183<h1 id="AUTHOR">AUTHOR</h1>
1691<div id="AUTHOR_CONTENT"> 2184<div id="AUTHOR_CONTENT">
1692 <p>Marc Lehmann &lt;libev@schmorp.de&gt;.</p> 2185 <p>Marc Lehmann &lt;libev@schmorp.de&gt;.</p>
1693 2186
1694</div> 2187</div>
1695</div></body> 2188</div></body>

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