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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 19:29:25 2007" />
10 <meta name="generator" content="Pod::Xhtml 1.57" /> 10 <meta name="generator" content="Pod::Xhtml 1.57" />
11<link rel="stylesheet" href="http://res.tst.eu/pod.css"/></head> 11<link rel="stylesheet" href="http://res.tst.eu/pod.css"/></head>
12<body> 12<body>
13<div class="pod"> 13<div class="pod">
14<!-- INDEX START --> 14<!-- INDEX START -->
15<h3 id="TOP">Index</h3> 15<h3 id="TOP">Index</h3>
16 16
17<ul><li><a href="#NAME">NAME</a></li> 17<ul><li><a href="#NAME">NAME</a></li>
18<li><a href="#SYNOPSIS">SYNOPSIS</a></li> 18<li><a href="#SYNOPSIS">SYNOPSIS</a></li>
19<li><a href="#EXAMPLE_PROGRAM">EXAMPLE PROGRAM</a></li>
19<li><a href="#DESCRIPTION">DESCRIPTION</a></li> 20<li><a href="#DESCRIPTION">DESCRIPTION</a></li>
20<li><a href="#FEATURES">FEATURES</a></li> 21<li><a href="#FEATURES">FEATURES</a></li>
21<li><a href="#CONVENTIONS">CONVENTIONS</a></li> 22<li><a href="#CONVENTIONS">CONVENTIONS</a></li>
22<li><a href="#TIME_REPRESENTATION">TIME REPRESENTATION</a></li> 23<li><a href="#TIME_REPRESENTATION">TIME REPRESENTATION</a></li>
23<li><a href="#GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</a></li> 24<li><a href="#GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</a></li>
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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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, long 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 is similar - the
187realloc C function, the semantics are identical). It is used to allocate 238semantics is identical - to the realloc C function). It is used to
188and free memory (no surprises here). If it returns zero when memory 239allocate and free memory (no surprises here). If it returns zero when
189needs to be allocated, the library might abort or take some potentially 240memory needs to be allocated, the library might abort or take some
190destructive action. The default is your system realloc function.</p> 241potentially destructive action. The default is your system realloc
242function.</p>
191 <p>You could override this function in high-availability programs to, say, 243 <p>You could override this function in high-availability programs to, say,
192free some memory if it cannot allocate memory, to use a special allocator, 244free some memory if it cannot allocate memory, to use a special allocator,
193or even to sleep a while and retry until some memory is available.</p> 245or even to sleep a while and retry until some memory is available.</p>
194 <p>Example: replace the libev allocator with one that waits a bit and then 246 <p>Example: Replace the libev allocator with one that waits a bit and then
195retries: better than mine).</p> 247retries).</p>
196<pre> static void * 248<pre> static void *
197 persistent_realloc (void *ptr, long size) 249 persistent_realloc (void *ptr, size_t size)
198 { 250 {
199 for (;;) 251 for (;;)
200 { 252 {
201 void *newptr = realloc (ptr, size); 253 void *newptr = realloc (ptr, size);
202 254
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219indicating the system call or subsystem causing the problem. If this 271indicating the system call or subsystem causing the problem. If this
220callback is set, then libev will expect it to remedy the sitution, no 272callback is set, then libev will expect it to remedy the sitution, no
221matter what, when it returns. That is, libev will generally retry the 273matter what, when it returns. That is, libev will generally retry the
222requested operation, or, if the condition doesn't go away, do bad stuff 274requested operation, or, if the condition doesn't go away, do bad stuff
223(such as abort).</p> 275(such as abort).</p>
224 <p>Example: do the same thing as libev does internally:</p> 276 <p>Example: This is basically the same thing that libev does internally, too.</p>
225<pre> static void 277<pre> static void
226 fatal_error (const char *msg) 278 fatal_error (const char *msg)
227 { 279 {
228 perror (msg); 280 perror (msg);
229 abort (); 281 abort ();
… …
235</pre> 287</pre>
236 </dd> 288 </dd>
237</dl> 289</dl>
238 290
239</div> 291</div>
240<h1 id="FUNCTIONS_CONTROLLING_THE_EVENT_LOOP">FUNCTIONS CONTROLLING THE EVENT LOOP</h1><p><a href="#TOP" class="toplink">Top</a></p> 292<h1 id="FUNCTIONS_CONTROLLING_THE_EVENT_LOOP">FUNCTIONS CONTROLLING THE EVENT LOOP</h1>
241<div id="FUNCTIONS_CONTROLLING_THE_EVENT_LOOP-2"> 293<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 294<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 295types of such loops, the <i>default</i> loop, which supports signals and child
244events, and dynamically created loops which do not.</p> 296events, and dynamically created loops which do not.</p>
245<p>If you use threads, a common model is to run the default event loop 297<p>If you use threads, a common model is to run the default event loop
… …
365 <dd> 417 <dd>
366 <p>Similar to <code>ev_default_loop</code>, but always creates a new event loop that is 418 <p>Similar to <code>ev_default_loop</code>, but always creates a new event loop that is
367always distinct from the default loop. Unlike the default loop, it cannot 419always 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 420handle signal and child watchers, and attempts to do so will be greeted by
369undefined behaviour (or a failed assertion if assertions are enabled).</p> 421undefined 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> 422 <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); 423<pre> struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);
372 if (!epoller) 424 if (!epoller)
373 fatal (&quot;no epoll found here, maybe it hides under your chair&quot;); 425 fatal (&quot;no epoll found here, maybe it hides under your chair&quot;);
374 426
375</pre> 427</pre>
… …
468 be handled here by queueing them when their watcher gets executed. 520 be handled here by queueing them when their watcher gets executed.
469 - If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK 521 - If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK
470 were used, return, otherwise continue with step *. 522 were used, return, otherwise continue with step *.
471 523
472</pre> 524</pre>
473 <p>Example: queue some jobs and then loop until no events are outsanding 525 <p>Example: Queue some jobs and then loop until no events are outsanding
474anymore.</p> 526anymore.</p>
475<pre> ... queue jobs here, make sure they register event watchers as long 527<pre> ... queue jobs here, make sure they register event watchers as long
476 ... as they still have work to do (even an idle watcher will do..) 528 ... as they still have work to do (even an idle watcher will do..)
477 ev_loop (my_loop, 0); 529 ev_loop (my_loop, 0);
478 ... jobs done. yeah! 530 ... jobs done. yeah!
… …
497example, libev itself uses this for its internal signal pipe: It is not 549example, libev itself uses this for its internal signal pipe: It is not
498visible to the libev user and should not keep <code>ev_loop</code> from exiting if 550visible to the libev user and should not keep <code>ev_loop</code> from exiting if
499no event watchers registered by it are active. It is also an excellent 551no event watchers registered by it are active. It is also an excellent
500way to do this for generic recurring timers or from within third-party 552way to do this for generic recurring timers or from within third-party
501libraries. Just remember to <i>unref after start</i> and <i>ref before stop</i>.</p> 553libraries. Just remember to <i>unref after start</i> and <i>ref before stop</i>.</p>
502 <p>Example: create a signal watcher, but keep it from keeping <code>ev_loop</code> 554 <p>Example: Create a signal watcher, but keep it from keeping <code>ev_loop</code>
503running when nothing else is active.</p> 555running when nothing else is active.</p>
504<pre> struct dv_signal exitsig; 556<pre> struct ev_signal exitsig;
505 ev_signal_init (&amp;exitsig, sig_cb, SIGINT); 557 ev_signal_init (&amp;exitsig, sig_cb, SIGINT);
506 ev_signal_start (myloop, &amp;exitsig); 558 ev_signal_start (loop, &amp;exitsig);
507 evf_unref (myloop); 559 evf_unref (loop);
508 560
509</pre> 561</pre>
510 <p>Example: for some weird reason, unregister the above signal handler again.</p> 562 <p>Example: For some weird reason, unregister the above signal handler again.</p>
511<pre> ev_ref (myloop); 563<pre> ev_ref (loop);
512 ev_signal_stop (myloop, &amp;exitsig); 564 ev_signal_stop (loop, &amp;exitsig);
513 565
514</pre> 566</pre>
515 </dd> 567 </dd>
516</dl> 568</dl>
517 569
570
571
572
573
518</div> 574</div>
519<h1 id="ANATOMY_OF_A_WATCHER">ANATOMY OF A WATCHER</h1><p><a href="#TOP" class="toplink">Top</a></p> 575<h1 id="ANATOMY_OF_A_WATCHER">ANATOMY OF A WATCHER</h1>
520<div id="ANATOMY_OF_A_WATCHER_CONTENT"> 576<div id="ANATOMY_OF_A_WATCHER_CONTENT">
521<p>A watcher is a structure that you create and register to record your 577<p>A watcher is a structure that you create and register to record your
522interest in some event. For instance, if you want to wait for STDIN to 578interest in some event. For instance, if you want to wait for STDIN to
523become readable, you would create an <code>ev_io</code> watcher for that:</p> 579become readable, you would create an <code>ev_io</code> watcher for that:</p>
524<pre> static void my_cb (struct ev_loop *loop, struct ev_io *w, int revents) 580<pre> static void my_cb (struct ev_loop *loop, struct ev_io *w, int revents)
… …
581 </dd> 637 </dd>
582 <dt><code>EV_CHILD</code></dt> 638 <dt><code>EV_CHILD</code></dt>
583 <dd> 639 <dd>
584 <p>The pid specified in the <code>ev_child</code> watcher has received a status change.</p> 640 <p>The pid specified in the <code>ev_child</code> watcher has received a status change.</p>
585 </dd> 641 </dd>
642 <dt><code>EV_STAT</code></dt>
643 <dd>
644 <p>The path specified in the <code>ev_stat</code> watcher changed its attributes somehow.</p>
645 </dd>
586 <dt><code>EV_IDLE</code></dt> 646 <dt><code>EV_IDLE</code></dt>
587 <dd> 647 <dd>
588 <p>The <code>ev_idle</code> watcher has determined that you have nothing better to do.</p> 648 <p>The <code>ev_idle</code> watcher has determined that you have nothing better to do.</p>
589 </dd> 649 </dd>
590 <dt><code>EV_PREPARE</code></dt> 650 <dt><code>EV_PREPARE</code></dt>
… …
595<code>ev_loop</code> has gathered them, but before it invokes any callbacks for any 655<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 656received 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 657many 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 658(for example, a <code>ev_prepare</code> watcher might start an idle watcher to keep
599<code>ev_loop</code> from blocking).</p> 659<code>ev_loop</code> from blocking).</p>
660 </dd>
661 <dt><code>EV_EMBED</code></dt>
662 <dd>
663 <p>The embedded event loop specified in the <code>ev_embed</code> watcher needs attention.</p>
664 </dd>
665 <dt><code>EV_FORK</code></dt>
666 <dd>
667 <p>The event loop has been resumed in the child process after fork (see
668<code>ev_fork</code>).</p>
600 </dd> 669 </dd>
601 <dt><code>EV_ERROR</code></dt> 670 <dt><code>EV_ERROR</code></dt>
602 <dd> 671 <dd>
603 <p>An unspecified error has occured, the watcher has been stopped. This might 672 <p>An unspecified error has occured, the watcher has been stopped. This might
604happen because the watcher could not be properly started because libev 673happen because the watcher could not be properly started because libev
… …
612programs, though, so beware.</p> 681programs, though, so beware.</p>
613 </dd> 682 </dd>
614</dl> 683</dl>
615 684
616</div> 685</div>
617<h2 id="SUMMARY_OF_GENERIC_WATCHER_FUNCTIONS">SUMMARY OF GENERIC WATCHER FUNCTIONS</h2> 686<h2 id="GENERIC_WATCHER_FUNCTIONS">GENERIC WATCHER FUNCTIONS</h2>
618<div id="SUMMARY_OF_GENERIC_WATCHER_FUNCTIONS-2"> 687<div id="GENERIC_WATCHER_FUNCTIONS_CONTENT">
619<p>In the following description, <code>TYPE</code> stands for the watcher type, 688<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> 689e.g. <code>timer</code> for <code>ev_timer</code> watchers and <code>io</code> for <code>ev_io</code> watchers.</p>
621<dl> 690<dl>
622 <dt><code>ev_init</code> (ev_TYPE *watcher, callback)</dt> 691 <dt><code>ev_init</code> (ev_TYPE *watcher, callback)</dt>
623 <dd> 692 <dd>
… …
627the type-specific <code>ev_TYPE_set</code> macro afterwards to initialise the 696the 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 697type-specific parts. For each type there is also a <code>ev_TYPE_init</code> macro
629which rolls both calls into one.</p> 698which rolls both calls into one.</p>
630 <p>You can reinitialise a watcher at any time as long as it has been stopped 699 <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> 700(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, 701 <p>The callback is always of type <code>void (*)(ev_loop *loop, ev_TYPE *watcher,
633int revents)</code>.</p> 702int revents)</code>.</p>
634 </dd> 703 </dd>
635 <dt><code>ev_TYPE_set</code> (ev_TYPE *, [args])</dt> 704 <dt><code>ev_TYPE_set</code> (ev_TYPE *, [args])</dt>
636 <dd> 705 <dd>
637 <p>This macro initialises the type-specific parts of a watcher. You need to 706 <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 743events 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 744is 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 745<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> 746libev (e.g. you cnanot <code>free ()</code> it).</p>
678 </dd> 747 </dd>
679 <dt>callback = ev_cb (ev_TYPE *watcher)</dt> 748 <dt>callback ev_cb (ev_TYPE *watcher)</dt>
680 <dd> 749 <dd>
681 <p>Returns the callback currently set on the watcher.</p> 750 <p>Returns the callback currently set on the watcher.</p>
682 </dd> 751 </dd>
683 <dt>ev_cb_set (ev_TYPE *watcher, callback)</dt> 752 <dt>ev_cb_set (ev_TYPE *watcher, callback)</dt>
684 <dd> 753 <dd>
… …
716 struct my_io *w = (struct my_io *)w_; 785 struct my_io *w = (struct my_io *)w_;
717 ... 786 ...
718 } 787 }
719 788
720</pre> 789</pre>
721<p>More interesting and less C-conformant ways of catsing your callback type 790<p>More interesting and less C-conformant ways of casting your callback type
722have been omitted....</p> 791instead have been omitted.</p>
792<p>Another common scenario is having some data structure with multiple
793watchers:</p>
794<pre> struct my_biggy
795 {
796 int some_data;
797 ev_timer t1;
798 ev_timer t2;
799 }
723 800
801</pre>
802<p>In this case getting the pointer to <code>my_biggy</code> is a bit more complicated,
803you need to use <code>offsetof</code>:</p>
804<pre> #include &lt;stddef.h&gt;
724 805
806 static void
807 t1_cb (EV_P_ struct ev_timer *w, int revents)
808 {
809 struct my_biggy big = (struct my_biggy *
810 (((char *)w) - offsetof (struct my_biggy, t1));
811 }
725 812
813 static void
814 t2_cb (EV_P_ struct ev_timer *w, int revents)
815 {
816 struct my_biggy big = (struct my_biggy *
817 (((char *)w) - offsetof (struct my_biggy, t2));
818 }
726 819
727 820
821
822
823</pre>
824
728</div> 825</div>
729<h1 id="WATCHER_TYPES">WATCHER TYPES</h1><p><a href="#TOP" class="toplink">Top</a></p> 826<h1 id="WATCHER_TYPES">WATCHER TYPES</h1>
730<div id="WATCHER_TYPES_CONTENT"> 827<div id="WATCHER_TYPES_CONTENT">
731<p>This section describes each watcher in detail, but will not repeat 828<p>This section describes each watcher in detail, but will not repeat
732information given in the last section.</p> 829information given in the last section. Any initialisation/set macros,
830functions and members specific to the watcher type are explained.</p>
831<p>Members are additionally marked with either <i>[read-only]</i>, meaning that,
832while the watcher is active, you can look at the member and expect some
833sensible content, but you must not modify it (you can modify it while the
834watcher is stopped to your hearts content), or <i>[read-write]</i>, which
835means you can expect it to have some sensible content while the watcher
836is active, but you can also modify it. Modifying it may not do something
837sensible or take immediate effect (or do anything at all), but libev will
838not crash or malfunction in any way.</p>
733 839
734 840
735 841
736 842
737 843
738</div> 844</div>
739<h2 id="code_ev_io_code_is_this_file_descrip"><code>ev_io</code> - is this file descriptor readable or writable</h2> 845<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"> 846<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 847<p>I/O watchers check whether a file descriptor is readable or writable
742in each iteration of the event loop (This behaviour is called 848in each iteration of the event loop, or, more precisely, when reading
743level-triggering because you keep receiving events as long as the 849would 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 850some data. This behaviour is called level-triggering because you keep
745act on the event and neither want to receive future events).</p> 851receiving events as long as the condition persists. Remember you can stop
852the watcher if you don't want to act on the event and neither want to
853receive future events.</p>
746<p>In general you can register as many read and/or write event watchers per 854<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 855fd 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 856descriptors to non-blocking mode is also usually a good idea (but not
749required if you know what you are doing).</p> 857required if you know what you are doing).</p>
750<p>You have to be careful with dup'ed file descriptors, though. Some backends 858<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 859(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 860descriptors correctly if you register interest in two or more fds pointing
753to the same underlying file/socket etc. description (that is, they share 861to the same underlying file/socket/etc. description (that is, they share
754the same underlying &quot;file open&quot;).</p> 862the 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 863<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 864(at the time of this writing, this includes only <code>EVBACKEND_SELECT</code> and
757<code>EVBACKEND_POLL</code>).</p> 865<code>EVBACKEND_POLL</code>).</p>
866<p>Another thing you have to watch out for is that it is quite easy to
867receive &quot;spurious&quot; readyness notifications, that is your callback might
868be called with <code>EV_READ</code> but a subsequent <code>read</code>(2) will actually block
869because there is no data. Not only are some backends known to create a
870lot of those (for example solaris ports), it is very easy to get into
871this situation even with a relatively standard program structure. Thus
872it is best to always use non-blocking I/O: An extra <code>read</code>(2) returning
873<code>EAGAIN</code> is far preferable to a program hanging until some data arrives.</p>
874<p>If you cannot run the fd in non-blocking mode (for example you should not
875play around with an Xlib connection), then you have to seperately re-test
876wether a file descriptor is really ready with a known-to-be good interface
877such as poll (fortunately in our Xlib example, Xlib already does this on
878its own, so its quite safe to use).</p>
758<dl> 879<dl>
759 <dt>ev_io_init (ev_io *, callback, int fd, int events)</dt> 880 <dt>ev_io_init (ev_io *, callback, int fd, int events)</dt>
760 <dt>ev_io_set (ev_io *, int fd, int events)</dt> 881 <dt>ev_io_set (ev_io *, int fd, int events)</dt>
761 <dd> 882 <dd>
762 <p>Configures an <code>ev_io</code> watcher. The fd is the file descriptor to rceeive 883 <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 | 884rceeive events for and events is either <code>EV_READ</code>, <code>EV_WRITE</code> or
764EV_WRITE</code> to receive the given events.</p> 885<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 886 </dd>
766epoll and solaris ports) can result in spurious readyness notifications 887 <dt>int fd [read-only]</dt>
767for file descriptors, so you practically need to use non-blocking I/O (and 888 <dd>
768treat callback invocation as hint only), or retest separately with a safe 889 <p>The file descriptor being watched.</p>
769interface before doing I/O (XLib can do this), or force the use of either 890 </dd>
770<code>EVBACKEND_SELECT</code> or <code>EVBACKEND_POLL</code>, which don't suffer from this 891 <dt>int events [read-only]</dt>
771problem. Also note that it is quite easy to have your callback invoked 892 <dd>
772when the readyness condition is no longer valid even when employing 893 <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> 894 </dd>
776</dl> 895</dl>
777<p>Example: call <code>stdin_readable_cb</code> when STDIN_FILENO has become, well 896<p>Example: Call <code>stdin_readable_cb</code> when STDIN_FILENO has become, well
778readable, but only once. Since it is likely line-buffered, you could 897readable, but only once. Since it is likely line-buffered, you could
779attempt to read a whole line in the callback:</p> 898attempt to read a whole line in the callback.</p>
780<pre> static void 899<pre> static void
781 stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents) 900 stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents)
782 { 901 {
783 ev_io_stop (loop, w); 902 ev_io_stop (loop, w);
784 .. read from stdin here (or from w-&gt;fd) and haqndle any I/O errors 903 .. read from stdin here (or from w-&gt;fd) and haqndle any I/O errors
… …
795 914
796 915
797</pre> 916</pre>
798 917
799</div> 918</div>
800<h2 id="code_ev_timer_code_relative_and_opti"><code>ev_timer</code> - relative and optionally recurring timeouts</h2> 919<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"> 920<div id="code_ev_timer_code_relative_and_opti-2">
802<p>Timer watchers are simple relative timers that generate an event after a 921<p>Timer watchers are simple relative timers that generate an event after a
803given time, and optionally repeating in regular intervals after that.</p> 922given 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 923<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 924times out after an hour and you reset your system clock to last years
… …
837repeating. The exact semantics are:</p> 956repeating. The exact semantics are:</p>
838 <p>If the timer is started but nonrepeating, stop it.</p> 957 <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 958 <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> 959value), or reset the running timer to the repeat value.</p>
841 <p>This sounds a bit complicated, but here is a useful and typical 960 <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 961example: 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 962idle 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 963say, 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 964this 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 965<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 966you 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> 967socket, you can stop the timer, and again will automatically restart it if
968need be.</p>
969 <p>You can also ignore the <code>after</code> value and <code>ev_timer_start</code> altogether
970and only ever use the <code>repeat</code> value:</p>
971<pre> ev_timer_init (timer, callback, 0., 5.);
972 ev_timer_again (loop, timer);
973 ...
974 timer-&gt;again = 17.;
975 ev_timer_again (loop, timer);
976 ...
977 timer-&gt;again = 10.;
978 ev_timer_again (loop, timer);
979
980</pre>
981 <p>This is more efficient then stopping/starting the timer eahc time you want
982to modify its timeout value.</p>
983 </dd>
984 <dt>ev_tstamp repeat [read-write]</dt>
985 <dd>
986 <p>The current <code>repeat</code> value. Will be used each time the watcher times out
987or <code>ev_timer_again</code> is called and determines the next timeout (if any),
988which is also when any modifications are taken into account.</p>
849 </dd> 989 </dd>
850</dl> 990</dl>
851<p>Example: create a timer that fires after 60 seconds.</p> 991<p>Example: Create a timer that fires after 60 seconds.</p>
852<pre> static void 992<pre> static void
853 one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) 993 one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents)
854 { 994 {
855 .. one minute over, w is actually stopped right here 995 .. one minute over, w is actually stopped right here
856 } 996 }
… …
858 struct ev_timer mytimer; 998 struct ev_timer mytimer;
859 ev_timer_init (&amp;mytimer, one_minute_cb, 60., 0.); 999 ev_timer_init (&amp;mytimer, one_minute_cb, 60., 0.);
860 ev_timer_start (loop, &amp;mytimer); 1000 ev_timer_start (loop, &amp;mytimer);
861 1001
862</pre> 1002</pre>
863<p>Example: create a timeout timer that times out after 10 seconds of 1003<p>Example: Create a timeout timer that times out after 10 seconds of
864inactivity.</p> 1004inactivity.</p>
865<pre> static void 1005<pre> static void
866 timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents) 1006 timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents)
867 { 1007 {
868 .. ten seconds without any activity 1008 .. ten seconds without any activity
… …
881 1021
882 1022
883</pre> 1023</pre>
884 1024
885</div> 1025</div>
886<h2 id="code_ev_periodic_code_to_cron_or_not"><code>ev_periodic</code> - to cron or not to cron</h2> 1026<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"> 1027<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 1028<p>Periodic watchers are also timers of a kind, but they are very versatile
889(and unfortunately a bit complex).</p> 1029(and unfortunately a bit complex).</p>
890<p>Unlike <code>ev_timer</code>'s, they are not based on real time (or relative time) 1030<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 1031but 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 1111 <p>Simply stops and restarts the periodic watcher again. This is only useful
972when you changed some parameters or the reschedule callback would return 1112when 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 1113a different time than the last time it was called (e.g. in a crond like
974program when the crontabs have changed).</p> 1114program when the crontabs have changed).</p>
975 </dd> 1115 </dd>
1116 <dt>ev_tstamp interval [read-write]</dt>
1117 <dd>
1118 <p>The current interval value. Can be modified any time, but changes only
1119take effect when the periodic timer fires or <code>ev_periodic_again</code> is being
1120called.</p>
1121 </dd>
1122 <dt>ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read-write]</dt>
1123 <dd>
1124 <p>The current reschedule callback, or <code>0</code>, if this functionality is
1125switched off. Can be changed any time, but changes only take effect when
1126the periodic timer fires or <code>ev_periodic_again</code> is being called.</p>
1127 </dd>
976</dl> 1128</dl>
977<p>Example: call a callback every hour, or, more precisely, whenever the 1129<p>Example: Call a callback every hour, or, more precisely, whenever the
978system clock is divisible by 3600. The callback invocation times have 1130system clock is divisible by 3600. The callback invocation times have
979potentially a lot of jittering, but good long-term stability.</p> 1131potentially a lot of jittering, but good long-term stability.</p>
980<pre> static void 1132<pre> static void
981 clock_cb (struct ev_loop *loop, struct ev_io *w, int revents) 1133 clock_cb (struct ev_loop *loop, struct ev_io *w, int revents)
982 { 1134 {
… …
986 struct ev_periodic hourly_tick; 1138 struct ev_periodic hourly_tick;
987 ev_periodic_init (&amp;hourly_tick, clock_cb, 0., 3600., 0); 1139 ev_periodic_init (&amp;hourly_tick, clock_cb, 0., 3600., 0);
988 ev_periodic_start (loop, &amp;hourly_tick); 1140 ev_periodic_start (loop, &amp;hourly_tick);
989 1141
990</pre> 1142</pre>
991<p>Example: the same as above, but use a reschedule callback to do it:</p> 1143<p>Example: The same as above, but use a reschedule callback to do it:</p>
992<pre> #include &lt;math.h&gt; 1144<pre> #include &lt;math.h&gt;
993 1145
994 static ev_tstamp 1146 static ev_tstamp
995 my_scheduler_cb (struct ev_periodic *w, ev_tstamp now) 1147 my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)
996 { 1148 {
… …
998 } 1150 }
999 1151
1000 ev_periodic_init (&amp;hourly_tick, clock_cb, 0., 0., my_scheduler_cb); 1152 ev_periodic_init (&amp;hourly_tick, clock_cb, 0., 0., my_scheduler_cb);
1001 1153
1002</pre> 1154</pre>
1003<p>Example: call a callback every hour, starting now:</p> 1155<p>Example: Call a callback every hour, starting now:</p>
1004<pre> struct ev_periodic hourly_tick; 1156<pre> struct ev_periodic hourly_tick;
1005 ev_periodic_init (&amp;hourly_tick, clock_cb, 1157 ev_periodic_init (&amp;hourly_tick, clock_cb,
1006 fmod (ev_now (loop), 3600.), 3600., 0); 1158 fmod (ev_now (loop), 3600.), 3600., 0);
1007 ev_periodic_start (loop, &amp;hourly_tick); 1159 ev_periodic_start (loop, &amp;hourly_tick);
1008 1160
… …
1010 1162
1011 1163
1012</pre> 1164</pre>
1013 1165
1014</div> 1166</div>
1015<h2 id="code_ev_signal_code_signal_me_when_a"><code>ev_signal</code> - signal me when a signal gets signalled</h2> 1167<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"> 1168<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 1169<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 1170signal 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 1171will try it's best to deliver signals synchronously, i.e. as part of the
1020normal event processing, like any other event.</p> 1172normal event processing, like any other event.</p>
… …
1029 <dt>ev_signal_set (ev_signal *, int signum)</dt> 1181 <dt>ev_signal_set (ev_signal *, int signum)</dt>
1030 <dd> 1182 <dd>
1031 <p>Configures the watcher to trigger on the given signal number (usually one 1183 <p>Configures the watcher to trigger on the given signal number (usually one
1032of the <code>SIGxxx</code> constants).</p> 1184of the <code>SIGxxx</code> constants).</p>
1033 </dd> 1185 </dd>
1186 <dt>int signum [read-only]</dt>
1187 <dd>
1188 <p>The signal the watcher watches out for.</p>
1189 </dd>
1034</dl> 1190</dl>
1035 1191
1036 1192
1037 1193
1038 1194
1039 1195
1040</div> 1196</div>
1041<h2 id="code_ev_child_code_wait_for_pid_stat"><code>ev_child</code> - wait for pid status changes</h2> 1197<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"> 1198<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 1199<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> 1200some child status changes (most typically when a child of yours dies).</p>
1045<dl> 1201<dl>
1046 <dt>ev_child_init (ev_child *, callback, int pid)</dt> 1202 <dt>ev_child_init (ev_child *, callback, int pid)</dt>
1047 <dt>ev_child_set (ev_child *, int pid)</dt> 1203 <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 1207at 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 1208the 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 1209<code>waitpid</code> documentation). The <code>rpid</code> member contains the pid of the
1054process causing the status change.</p> 1210process causing the status change.</p>
1055 </dd> 1211 </dd>
1212 <dt>int pid [read-only]</dt>
1213 <dd>
1214 <p>The process id this watcher watches out for, or <code>0</code>, meaning any process id.</p>
1215 </dd>
1216 <dt>int rpid [read-write]</dt>
1217 <dd>
1218 <p>The process id that detected a status change.</p>
1219 </dd>
1220 <dt>int rstatus [read-write]</dt>
1221 <dd>
1222 <p>The process exit/trace status caused by <code>rpid</code> (see your systems
1223<code>waitpid</code> and <code>sys/wait.h</code> documentation for details).</p>
1224 </dd>
1056</dl> 1225</dl>
1057<p>Example: try to exit cleanly on SIGINT and SIGTERM.</p> 1226<p>Example: Try to exit cleanly on SIGINT and SIGTERM.</p>
1058<pre> static void 1227<pre> static void
1059 sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) 1228 sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents)
1060 { 1229 {
1061 ev_unloop (loop, EVUNLOOP_ALL); 1230 ev_unloop (loop, EVUNLOOP_ALL);
1062 } 1231 }
… …
1069 1238
1070 1239
1071</pre> 1240</pre>
1072 1241
1073</div> 1242</div>
1243<h2 id="code_ev_stat_code_did_the_file_attri"><code>ev_stat</code> - did the file attributes just change?</h2>
1244<div id="code_ev_stat_code_did_the_file_attri-2">
1245<p>This watches a filesystem path for attribute changes. That is, it calls
1246<code>stat</code> regularly (or when the OS says it changed) and sees if it changed
1247compared to the last time, invoking the callback if it did.</p>
1248<p>The path does not need to exist: changing from &quot;path exists&quot; to &quot;path does
1249not exist&quot; is a status change like any other. The condition &quot;path does
1250not exist&quot; is signified by the <code>st_nlink</code> field being zero (which is
1251otherwise always forced to be at least one) and all the other fields of
1252the stat buffer having unspecified contents.</p>
1253<p>The path <i>should</i> be absolute and <i>must not</i> end in a slash. If it is
1254relative and your working directory changes, the behaviour is undefined.</p>
1255<p>Since there is no standard to do this, the portable implementation simply
1256calls <code>stat (2)</code> regularly on the path to see if it changed somehow. You
1257can specify a recommended polling interval for this case. If you specify
1258a polling interval of <code>0</code> (highly recommended!) then a <i>suitable,
1259unspecified default</i> value will be used (which you can expect to be around
1260five seconds, although this might change dynamically). Libev will also
1261impose a minimum interval which is currently around <code>0.1</code>, but thats
1262usually overkill.</p>
1263<p>This watcher type is not meant for massive numbers of stat watchers,
1264as even with OS-supported change notifications, this can be
1265resource-intensive.</p>
1266<p>At the time of this writing, only the Linux inotify interface is
1267implemented (implementing kqueue support is left as an exercise for the
1268reader). Inotify will be used to give hints only and should not change the
1269semantics of <code>ev_stat</code> watchers, which means that libev sometimes needs
1270to fall back to regular polling again even with inotify, but changes are
1271usually detected immediately, and if the file exists there will be no
1272polling.</p>
1273<dl>
1274 <dt>ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)</dt>
1275 <dt>ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)</dt>
1276 <dd>
1277 <p>Configures the watcher to wait for status changes of the given
1278<code>path</code>. The <code>interval</code> is a hint on how quickly a change is expected to
1279be detected and should normally be specified as <code>0</code> to let libev choose
1280a suitable value. The memory pointed to by <code>path</code> must point to the same
1281path for as long as the watcher is active.</p>
1282 <p>The callback will be receive <code>EV_STAT</code> when a change was detected,
1283relative to the attributes at the time the watcher was started (or the
1284last change was detected).</p>
1285 </dd>
1286 <dt>ev_stat_stat (ev_stat *)</dt>
1287 <dd>
1288 <p>Updates the stat buffer immediately with new values. If you change the
1289watched path in your callback, you could call this fucntion to avoid
1290detecting this change (while introducing a race condition). Can also be
1291useful simply to find out the new values.</p>
1292 </dd>
1293 <dt>ev_statdata attr [read-only]</dt>
1294 <dd>
1295 <p>The most-recently detected attributes of the file. Although the type is of
1296<code>ev_statdata</code>, this is usually the (or one of the) <code>struct stat</code> types
1297suitable for your system. If the <code>st_nlink</code> member is <code>0</code>, then there
1298was some error while <code>stat</code>ing the file.</p>
1299 </dd>
1300 <dt>ev_statdata prev [read-only]</dt>
1301 <dd>
1302 <p>The previous attributes of the file. The callback gets invoked whenever
1303<code>prev</code> != <code>attr</code>.</p>
1304 </dd>
1305 <dt>ev_tstamp interval [read-only]</dt>
1306 <dd>
1307 <p>The specified interval.</p>
1308 </dd>
1309 <dt>const char *path [read-only]</dt>
1310 <dd>
1311 <p>The filesystem path that is being watched.</p>
1312 </dd>
1313</dl>
1314<p>Example: Watch <code>/etc/passwd</code> for attribute changes.</p>
1315<pre> static void
1316 passwd_cb (struct ev_loop *loop, ev_stat *w, int revents)
1317 {
1318 /* /etc/passwd changed in some way */
1319 if (w-&gt;attr.st_nlink)
1320 {
1321 printf (&quot;passwd current size %ld\n&quot;, (long)w-&gt;attr.st_size);
1322 printf (&quot;passwd current atime %ld\n&quot;, (long)w-&gt;attr.st_mtime);
1323 printf (&quot;passwd current mtime %ld\n&quot;, (long)w-&gt;attr.st_mtime);
1324 }
1325 else
1326 /* you shalt not abuse printf for puts */
1327 puts (&quot;wow, /etc/passwd is not there, expect problems. &quot;
1328 &quot;if this is windows, they already arrived\n&quot;);
1329 }
1330
1331 ...
1332 ev_stat passwd;
1333
1334 ev_stat_init (&amp;passwd, passwd_cb, &quot;/etc/passwd&quot;);
1335 ev_stat_start (loop, &amp;passwd);
1336
1337
1338
1339
1340</pre>
1341
1342</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> 1343<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"> 1344<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 1345<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 1346(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, 1347as 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 1348imagine) 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 1361 <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, 1362kind. There is a <code>ev_idle_set</code> macro, but using it is utterly pointless,
1094believe me.</p> 1363believe me.</p>
1095 </dd> 1364 </dd>
1096</dl> 1365</dl>
1097<p>Example: dynamically allocate an <code>ev_idle</code>, start it, and in the 1366<p>Example: Dynamically allocate an <code>ev_idle</code> watcher, start it, and in the
1098callback, free it. Alos, use no error checking, as usual.</p> 1367callback, free it. Also, use no error checking, as usual.</p>
1099<pre> static void 1368<pre> static void
1100 idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents) 1369 idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents)
1101 { 1370 {
1102 free (w); 1371 free (w);
1103 // now do something you wanted to do when the program has 1372 // now do something you wanted to do when the program has
… …
1112 1381
1113 1382
1114</pre> 1383</pre>
1115 1384
1116</div> 1385</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> 1386<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"> 1387<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: 1388<p>Prepare and check watchers are usually (but not always) used in tandem:
1120prepare watchers get invoked before the process blocks and check watchers 1389prepare watchers get invoked before the process blocks and check watchers
1121afterwards.</p> 1390afterwards.</p>
1391<p>You <i>must not</i> call <code>ev_loop</code> or similar functions that enter
1392the current event loop from either <code>ev_prepare</code> or <code>ev_check</code>
1393watchers. Other loops than the current one are fine, however. The
1394rationale behind this is that you do not need to check for recursion in
1395those watchers, i.e. the sequence will always be <code>ev_prepare</code>, blocking,
1396<code>ev_check</code> so if you have one watcher of each kind they will always be
1397called in pairs bracketing the blocking call.</p>
1122<p>Their main purpose is to integrate other event mechanisms into libev and 1398<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 1399their use is somewhat advanced. This could be used, for example, to track
1124variable changes, implement your own watchers, integrate net-snmp or a 1400variable changes, implement your own watchers, integrate net-snmp or a
1125coroutine library and lots more.</p> 1401coroutine library and lots more. They are also occasionally useful if
1402you cache some data and want to flush it before blocking (for example,
1403in X programs you might want to do an <code>XFlush ()</code> in an <code>ev_prepare</code>
1404watcher).</p>
1126<p>This is done by examining in each prepare call which file descriptors need 1405<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 1406to 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 1407them 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 1408provide just this functionality). Then, in the check watcher you check for
1130any events that occured (by checking the pending status of all watchers 1409any events that occured (by checking the pending status of all watchers
… …
1146 <p>Initialises and configures the prepare or check watcher - they have no 1425 <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> 1426parameters 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> 1427macros, but using them is utterly, utterly and completely pointless.</p>
1149 </dd> 1428 </dd>
1150</dl> 1429</dl>
1151<p>Example: *TODO*.</p> 1430<p>Example: To include a library such as adns, you would add IO watchers
1431and a timeout watcher in a prepare handler, as required by libadns, and
1432in a check watcher, destroy them and call into libadns. What follows is
1433pseudo-code only of course:</p>
1434<pre> static ev_io iow [nfd];
1435 static ev_timer tw;
1152 1436
1437 static void
1438 io_cb (ev_loop *loop, ev_io *w, int revents)
1439 {
1440 // set the relevant poll flags
1441 // could also call adns_processreadable etc. here
1442 struct pollfd *fd = (struct pollfd *)w-&gt;data;
1443 if (revents &amp; EV_READ ) fd-&gt;revents |= fd-&gt;events &amp; POLLIN;
1444 if (revents &amp; EV_WRITE) fd-&gt;revents |= fd-&gt;events &amp; POLLOUT;
1445 }
1153 1446
1447 // create io watchers for each fd and a timer before blocking
1448 static void
1449 adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents)
1450 {
1451 int timeout = 3600000;truct pollfd fds [nfd];
1452 // actual code will need to loop here and realloc etc.
1453 adns_beforepoll (ads, fds, &amp;nfd, &amp;timeout, timeval_from (ev_time ()));
1154 1454
1455 /* the callback is illegal, but won't be called as we stop during check */
1456 ev_timer_init (&amp;tw, 0, timeout * 1e-3);
1457 ev_timer_start (loop, &amp;tw);
1155 1458
1459 // create on ev_io per pollfd
1460 for (int i = 0; i &lt; nfd; ++i)
1461 {
1462 ev_io_init (iow + i, io_cb, fds [i].fd,
1463 ((fds [i].events &amp; POLLIN ? EV_READ : 0)
1464 | (fds [i].events &amp; POLLOUT ? EV_WRITE : 0)));
1156 1465
1466 fds [i].revents = 0;
1467 iow [i].data = fds + i;
1468 ev_io_start (loop, iow + i);
1469 }
1470 }
1471
1472 // stop all watchers after blocking
1473 static void
1474 adns_check_cb (ev_loop *loop, ev_check *w, int revents)
1475 {
1476 ev_timer_stop (loop, &amp;tw);
1477
1478 for (int i = 0; i &lt; nfd; ++i)
1479 ev_io_stop (loop, iow + i);
1480
1481 adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));
1482 }
1483
1484
1485
1486
1487</pre>
1488
1157</div> 1489</div>
1158<h2 id="code_ev_embed_code_when_one_backend_"><code>ev_embed</code> - when one backend isn't enough</h2> 1490<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"> 1491<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 1492<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 1493into 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 1494loop, other types of watchers might be handled in a delayed or incorrect
1163fashion and must not be used).</p> 1495fashion and must not be used).</p>
… …
1231 <dd> 1563 <dd>
1232 <p>Make a single, non-blocking sweep over the embedded loop. This works 1564 <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 1565similarly to <code>ev_loop (embedded_loop, EVLOOP_NONBLOCK)</code>, but in the most
1234apropriate way for embedded loops.</p> 1566apropriate way for embedded loops.</p>
1235 </dd> 1567 </dd>
1568 <dt>struct ev_loop *loop [read-only]</dt>
1569 <dd>
1570 <p>The embedded event loop.</p>
1571 </dd>
1236</dl> 1572</dl>
1237 1573
1238 1574
1239 1575
1240 1576
1241 1577
1242</div> 1578</div>
1243<h1 id="OTHER_FUNCTIONS">OTHER FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p> 1579<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>
1580<div id="code_ev_fork_code_the_audacity_to_re-2">
1581<p>Fork watchers are called when a <code>fork ()</code> was detected (usually because
1582whoever is a good citizen cared to tell libev about it by calling
1583<code>ev_default_fork</code> or <code>ev_loop_fork</code>). The invocation is done before the
1584event loop blocks next and before <code>ev_check</code> watchers are being called,
1585and only in the child after the fork. If whoever good citizen calling
1586<code>ev_default_fork</code> cheats and calls it in the wrong process, the fork
1587handlers will be invoked, too, of course.</p>
1588<dl>
1589 <dt>ev_fork_init (ev_signal *, callback)</dt>
1590 <dd>
1591 <p>Initialises and configures the fork watcher - it has no parameters of any
1592kind. There is a <code>ev_fork_set</code> macro, but using it is utterly pointless,
1593believe me.</p>
1594 </dd>
1595</dl>
1596
1597
1598
1599
1600
1601</div>
1602<h1 id="OTHER_FUNCTIONS">OTHER FUNCTIONS</h1>
1244<div id="OTHER_FUNCTIONS_CONTENT"> 1603<div id="OTHER_FUNCTIONS_CONTENT">
1245<p>There are some other functions of possible interest. Described. Here. Now.</p> 1604<p>There are some other functions of possible interest. Described. Here. Now.</p>
1246<dl> 1605<dl>
1247 <dt>ev_once (loop, int fd, int events, ev_tstamp timeout, callback)</dt> 1606 <dt>ev_once (loop, int fd, int events, ev_tstamp timeout, callback)</dt>
1248 <dd> 1607 <dd>
… …
1295 1654
1296 1655
1297 1656
1298 1657
1299</div> 1658</div>
1300<h1 id="LIBEVENT_EMULATION">LIBEVENT EMULATION</h1><p><a href="#TOP" class="toplink">Top</a></p> 1659<h1 id="LIBEVENT_EMULATION">LIBEVENT EMULATION</h1>
1301<div id="LIBEVENT_EMULATION_CONTENT"> 1660<div id="LIBEVENT_EMULATION_CONTENT">
1302<p>Libev offers a compatibility emulation layer for libevent. It cannot 1661<p>Libev offers a compatibility emulation layer for libevent. It cannot
1303emulate the internals of libevent, so here are some usage hints:</p> 1662emulate the internals of libevent, so here are some usage hints:</p>
1304<dl> 1663<dl>
1305 <dt>* Use it by including &lt;event.h&gt;, as usual.</dt> 1664 <dt>* Use it by including &lt;event.h&gt;, as usual.</dt>
… …
1315 <dt>* The libev emulation is <i>not</i> ABI compatible to libevent, you need 1674 <dt>* The libev emulation is <i>not</i> ABI compatible to libevent, you need
1316to use the libev header file and library.</dt> 1675to use the libev header file and library.</dt>
1317</dl> 1676</dl>
1318 1677
1319</div> 1678</div>
1320<h1 id="C_SUPPORT">C++ SUPPORT</h1><p><a href="#TOP" class="toplink">Top</a></p> 1679<h1 id="C_SUPPORT">C++ SUPPORT</h1>
1321<div id="C_SUPPORT_CONTENT"> 1680<div id="C_SUPPORT_CONTENT">
1322<p>Libev comes with some simplistic wrapper classes for C++ that mainly allow 1681<p>Libev comes with some simplistic wrapper classes for C++ that mainly allow
1323you to use some convinience methods to start/stop watchers and also change 1682you to use some convinience methods to start/stop watchers and also change
1324the callback model to a model using method callbacks on objects.</p> 1683the callback model to a model using method callbacks on objects.</p>
1325<p>To use it,</p> 1684<p>To use it,</p>
… …
1389 </dd> 1748 </dd>
1390 <dt>w-&gt;sweep () <code>ev::embed</code> only</dt> 1749 <dt>w-&gt;sweep () <code>ev::embed</code> only</dt>
1391 <dd> 1750 <dd>
1392 <p>Invokes <code>ev_embed_sweep</code>.</p> 1751 <p>Invokes <code>ev_embed_sweep</code>.</p>
1393 </dd> 1752 </dd>
1753 <dt>w-&gt;update () <code>ev::stat</code> only</dt>
1754 <dd>
1755 <p>Invokes <code>ev_stat_stat</code>.</p>
1756 </dd>
1394 </dl> 1757 </dl>
1395 </p> 1758 </p>
1396 </dd> 1759 </dd>
1397</dl> 1760</dl>
1398<p>Example: Define a class with an IO and idle watcher, start one of them in 1761<p>Example: Define a class with an IO and idle watcher, start one of them in
… …
1410 idle (this, &amp;myclass::idle_cb) 1773 idle (this, &amp;myclass::idle_cb)
1411 { 1774 {
1412 io.start (fd, ev::READ); 1775 io.start (fd, ev::READ);
1413 } 1776 }
1414 1777
1415</pre>
1416 1778
1779
1780
1781</pre>
1782
1417</div> 1783</div>
1418<h1 id="EMBEDDING">EMBEDDING</h1><p><a href="#TOP" class="toplink">Top</a></p> 1784<h1 id="MACRO_MAGIC">MACRO MAGIC</h1>
1785<div id="MACRO_MAGIC_CONTENT">
1786<p>Libev can be compiled with a variety of options, the most fundemantal is
1787<code>EV_MULTIPLICITY</code>. This option determines wether (most) functions and
1788callbacks have an initial <code>struct ev_loop *</code> argument.</p>
1789<p>To make it easier to write programs that cope with either variant, the
1790following macros are defined:</p>
1791<dl>
1792 <dt><code>EV_A</code>, <code>EV_A_</code></dt>
1793 <dd>
1794 <p>This provides the loop <i>argument</i> for functions, if one is required (&quot;ev
1795loop argument&quot;). The <code>EV_A</code> form is used when this is the sole argument,
1796<code>EV_A_</code> is used when other arguments are following. Example:</p>
1797<pre> ev_unref (EV_A);
1798 ev_timer_add (EV_A_ watcher);
1799 ev_loop (EV_A_ 0);
1800
1801</pre>
1802 <p>It assumes the variable <code>loop</code> of type <code>struct ev_loop *</code> is in scope,
1803which is often provided by the following macro.</p>
1804 </dd>
1805 <dt><code>EV_P</code>, <code>EV_P_</code></dt>
1806 <dd>
1807 <p>This provides the loop <i>parameter</i> for functions, if one is required (&quot;ev
1808loop parameter&quot;). The <code>EV_P</code> form is used when this is the sole parameter,
1809<code>EV_P_</code> is used when other parameters are following. Example:</p>
1810<pre> // this is how ev_unref is being declared
1811 static void ev_unref (EV_P);
1812
1813 // this is how you can declare your typical callback
1814 static void cb (EV_P_ ev_timer *w, int revents)
1815
1816</pre>
1817 <p>It declares a parameter <code>loop</code> of type <code>struct ev_loop *</code>, quite
1818suitable for use with <code>EV_A</code>.</p>
1819 </dd>
1820 <dt><code>EV_DEFAULT</code>, <code>EV_DEFAULT_</code></dt>
1821 <dd>
1822 <p>Similar to the other two macros, this gives you the value of the default
1823loop, if multiple loops are supported (&quot;ev loop default&quot;).</p>
1824 </dd>
1825</dl>
1826<p>Example: Declare and initialise a check watcher, working regardless of
1827wether multiple loops are supported or not.</p>
1828<pre> static void
1829 check_cb (EV_P_ ev_timer *w, int revents)
1830 {
1831 ev_check_stop (EV_A_ w);
1832 }
1833
1834 ev_check check;
1835 ev_check_init (&amp;check, check_cb);
1836 ev_check_start (EV_DEFAULT_ &amp;check);
1837 ev_loop (EV_DEFAULT_ 0);
1838
1839
1840
1841
1842</pre>
1843
1844</div>
1845<h1 id="EMBEDDING">EMBEDDING</h1>
1419<div id="EMBEDDING_CONTENT"> 1846<div id="EMBEDDING_CONTENT">
1420<p>Libev can (and often is) directly embedded into host 1847<p>Libev can (and often is) directly embedded into host
1421applications. Examples of applications that embed it include the Deliantra 1848applications. Examples of applications that embed it include the Deliantra
1422Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe) 1849Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe)
1423and rxvt-unicode.</p> 1850and rxvt-unicode.</p>
… …
1460 ev_vars.h 1887 ev_vars.h
1461 ev_wrap.h 1888 ev_wrap.h
1462 1889
1463 ev_win32.c required on win32 platforms only 1890 ev_win32.c required on win32 platforms only
1464 1891
1465 ev_select.c only when select backend is enabled (which is is by default) 1892 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) 1893 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) 1894 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) 1895 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) 1896 ev_port.c only when the solaris port backend is enabled (disabled by default)
1470 1897
1471</pre> 1898</pre>
1472<p><cite>ev.c</cite> includes the backend files directly when enabled, so you only need 1899<p><cite>ev.c</cite> includes the backend files directly when enabled, so you only need
1473to compile a single file.</p> 1900to compile this single file.</p>
1474 1901
1475</div> 1902</div>
1476<h3 id="LIBEVENT_COMPATIBILITY_API">LIBEVENT COMPATIBILITY API</h3> 1903<h3 id="LIBEVENT_COMPATIBILITY_API">LIBEVENT COMPATIBILITY API</h3>
1477<div id="LIBEVENT_COMPATIBILITY_API_CONTENT"> 1904<div id="LIBEVENT_COMPATIBILITY_API_CONTENT">
1478<p>To include the libevent compatibility API, also include:</p> 1905<p>To include the libevent compatibility API, also include:</p>
… …
1493</div> 1920</div>
1494<h3 id="AUTOCONF_SUPPORT">AUTOCONF SUPPORT</h3> 1921<h3 id="AUTOCONF_SUPPORT">AUTOCONF SUPPORT</h3>
1495<div id="AUTOCONF_SUPPORT_CONTENT"> 1922<div id="AUTOCONF_SUPPORT_CONTENT">
1496<p>Instead of using <code>EV_STANDALONE=1</code> and providing your config in 1923<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 1924whatever 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 1925<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> 1926include <cite>config.h</cite> and configure itself accordingly.</p>
1500<p>For this of course you need the m4 file:</p> 1927<p>For this of course you need the m4 file:</p>
1501<pre> libev.m4 1928<pre> libev.m4
1502 1929
1503</pre> 1930</pre>
1504 1931
… …
1583otherwise another method will be used as fallback. This is the preferred 2010otherwise another method will be used as fallback. This is the preferred
1584backend for BSD and BSD-like systems, although on most BSDs kqueue only 2011backend for BSD and BSD-like systems, although on most BSDs kqueue only
1585supports some types of fds correctly (the only platform we found that 2012supports some types of fds correctly (the only platform we found that
1586supports ptys for example was NetBSD), so kqueue might be compiled in, but 2013supports 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 2014not 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 2015out whether kqueue supports your type of fd properly and use an embedded
1589kqueue loop.</p> 2016kqueue loop.</p>
1590 </dd> 2017 </dd>
1591 <dt>EV_USE_PORT</dt> 2018 <dt>EV_USE_PORT</dt>
1592 <dd> 2019 <dd>
1593 <p>If defined to be <code>1</code>, libev will compile in support for the Solaris 2020 <p>If defined to be <code>1</code>, libev will compile in support for the Solaris
… …
1596backend for Solaris 10 systems.</p> 2023backend for Solaris 10 systems.</p>
1597 </dd> 2024 </dd>
1598 <dt>EV_USE_DEVPOLL</dt> 2025 <dt>EV_USE_DEVPOLL</dt>
1599 <dd> 2026 <dd>
1600 <p>reserved for future expansion, works like the USE symbols above.</p> 2027 <p>reserved for future expansion, works like the USE symbols above.</p>
2028 </dd>
2029 <dt>EV_USE_INOTIFY</dt>
2030 <dd>
2031 <p>If defined to be <code>1</code>, libev will compile in support for the Linux inotify
2032interface to speed up <code>ev_stat</code> watchers. Its actual availability will
2033be detected at runtime.</p>
1601 </dd> 2034 </dd>
1602 <dt>EV_H</dt> 2035 <dt>EV_H</dt>
1603 <dd> 2036 <dd>
1604 <p>The name of the <cite>ev.h</cite> header file used to include it. The default if 2037 <p>The name of the <cite>ev.h</cite> header file used to include it. The default if
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 2038undefined is <code>&lt;ev.h&gt;</code> in <cite>event.h</cite> and <code>&quot;ev.h&quot;</code> in <cite>ev.c</cite>. This
… …
1629will have the <code>struct ev_loop *</code> as first argument, and you can create 2062will have the <code>struct ev_loop *</code> as first argument, and you can create
1630additional independent event loops. Otherwise there will be no support 2063additional independent event loops. Otherwise there will be no support
1631for multiple event loops and there is no first event loop pointer 2064for multiple event loops and there is no first event loop pointer
1632argument. Instead, all functions act on the single default loop.</p> 2065argument. Instead, all functions act on the single default loop.</p>
1633 </dd> 2066 </dd>
1634 <dt>EV_PERIODICS</dt> 2067 <dt>EV_PERIODIC_ENABLE</dt>
1635 <dd> 2068 <dd>
1636 <p>If undefined or defined to be <code>1</code>, then periodic timers are supported, 2069 <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> 2070defined to be <code>0</code>, then they are not. Disabling them saves a few kB of
2071code.</p>
2072 </dd>
2073 <dt>EV_EMBED_ENABLE</dt>
2074 <dd>
2075 <p>If undefined or defined to be <code>1</code>, then embed watchers are supported. If
2076defined to be <code>0</code>, then they are not.</p>
2077 </dd>
2078 <dt>EV_STAT_ENABLE</dt>
2079 <dd>
2080 <p>If undefined or defined to be <code>1</code>, then stat watchers are supported. If
2081defined to be <code>0</code>, then they are not.</p>
2082 </dd>
2083 <dt>EV_FORK_ENABLE</dt>
2084 <dd>
2085 <p>If undefined or defined to be <code>1</code>, then fork watchers are supported. If
2086defined to be <code>0</code>, then they are not.</p>
2087 </dd>
2088 <dt>EV_MINIMAL</dt>
2089 <dd>
2090 <p>If you need to shave off some kilobytes of code at the expense of some
2091speed, define this symbol to <code>1</code>. Currently only used for gcc to override
2092some inlining decisions, saves roughly 30% codesize of amd64.</p>
2093 </dd>
2094 <dt>EV_PID_HASHSIZE</dt>
2095 <dd>
2096 <p><code>ev_child</code> watchers use a small hash table to distribute workload by
2097pid. The default size is <code>16</code> (or <code>1</code> with <code>EV_MINIMAL</code>), usually more
2098than enough. If you need to manage thousands of children you might want to
2099increase this value (<i>must</i> be a power of two).</p>
2100 </dd>
2101 <dt>EV_INOTIFY_HASHSIZE</dt>
2102 <dd>
2103 <p><code>ev_staz</code> watchers use a small hash table to distribute workload by
2104inotify watch id. The default size is <code>16</code> (or <code>1</code> with <code>EV_MINIMAL</code>),
2105usually more than enough. If you need to manage thousands of <code>ev_stat</code>
2106watchers you might want to increase this value (<i>must</i> be a power of
2107two).</p>
1638 </dd> 2108 </dd>
1639 <dt>EV_COMMON</dt> 2109 <dt>EV_COMMON</dt>
1640 <dd> 2110 <dd>
1641 <p>By default, all watchers have a <code>void *data</code> member. By redefining 2111 <p>By default, all watchers have a <code>void *data</code> member. By redefining
1642this macro to a something else you can include more and other types of 2112this macro to a something else you can include more and other types of
… …
1647 SV *self; /* contains this struct */ \ 2117 SV *self; /* contains this struct */ \
1648 SV *cb_sv, *fh /* note no trailing &quot;;&quot; */ 2118 SV *cb_sv, *fh /* note no trailing &quot;;&quot; */
1649 2119
1650</pre> 2120</pre>
1651 </dd> 2121 </dd>
1652 <dt>EV_CB_DECLARE(type)</dt> 2122 <dt>EV_CB_DECLARE (type)</dt>
1653 <dt>EV_CB_INVOKE(watcher,revents)</dt> 2123 <dt>EV_CB_INVOKE (watcher, revents)</dt>
1654 <dt>ev_set_cb(ev,cb)</dt> 2124 <dt>ev_set_cb (ev, cb)</dt>
1655 <dd> 2125 <dd>
1656 <p>Can be used to change the callback member declaration in each watcher, 2126 <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 2127and 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 2128definition and a statement, respectively. See the <cite>ev.v</cite> header file for
1659their default definitions. One possible use for overriding these is to 2129their 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 2130avoid the <code>struct ev_loop *</code> as first argument in all cases, or to use
1661calls instead of plain function calls in C++.</p> 2131method calls instead of plain function calls in C++.</p>
1662 2132
1663</div> 2133</div>
1664<h2 id="EXAMPLES">EXAMPLES</h2> 2134<h2 id="EXAMPLES">EXAMPLES</h2>
1665<div id="EXAMPLES_CONTENT"> 2135<div id="EXAMPLES_CONTENT">
1666 <p>For a real-world example of a program the includes libev 2136 <p>For a real-world example of a program the includes libev
… …
1682</pre> 2152</pre>
1683 <p>And a <cite>ev_cpp.C</cite> implementation file that contains libev proper and is compiled:</p> 2153 <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; 2154<pre> #include &quot;ev_cpp.h&quot;
1685 #include &quot;ev.c&quot; 2155 #include &quot;ev.c&quot;
1686 2156
1687</pre>
1688 2157
2158
2159
2160</pre>
2161
1689</div> 2162</div>
1690<h1 id="AUTHOR">AUTHOR</h1><p><a href="#TOP" class="toplink">Top</a></p> 2163<h1 id="COMPLEXITIES">COMPLEXITIES</h1>
2164<div id="COMPLEXITIES_CONTENT">
2165 <p>In this section the complexities of (many of) the algorithms used inside
2166libev will be explained. For complexity discussions about backends see the
2167documentation for <code>ev_default_init</code>.</p>
2168 <p>
2169 <dl>
2170 <dt>Starting and stopping timer/periodic watchers: O(log skipped_other_timers)</dt>
2171 <dt>Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)</dt>
2172 <dt>Starting io/check/prepare/idle/signal/child watchers: O(1)</dt>
2173 <dt>Stopping check/prepare/idle watchers: O(1)</dt>
2174 <dt>Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))</dt>
2175 <dt>Finding the next timer per loop iteration: O(1)</dt>
2176 <dt>Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)</dt>
2177 <dt>Activating one watcher: O(1)</dt>
2178 </dl>
2179 </p>
2180
2181
2182
2183
2184
2185</div>
2186<h1 id="AUTHOR">AUTHOR</h1>
1691<div id="AUTHOR_CONTENT"> 2187<div id="AUTHOR_CONTENT">
1692 <p>Marc Lehmann &lt;libev@schmorp.de&gt;.</p> 2188 <p>Marc Lehmann &lt;libev@schmorp.de&gt;.</p>
1693 2189
1694</div> 2190</div>
1695</div></body> 2191</div></body>

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