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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 11:19:13 2007" /> 9 <meta name="created" content="Fri Dec 7 17:49:47 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
… …
273or setgid) then libev will <i>not</i> look at the environment variable 325or setgid) then libev will <i>not</i> look at the environment variable
274<code>LIBEV_FLAGS</code>. Otherwise (the default), this environment variable will 326<code>LIBEV_FLAGS</code>. Otherwise (the default), this environment variable will
275override the flags completely if it is found in the environment. This is 327override the flags completely if it is found in the environment. This is
276useful to try out specific backends to test their performance, or to work 328useful to try out specific backends to test their performance, or to work
277around bugs.</p> 329around bugs.</p>
330 </dd>
331 <dt><code>EVFLAG_FORKCHECK</code></dt>
332 <dd>
333 <p>Instead of calling <code>ev_default_fork</code> or <code>ev_loop_fork</code> manually after
334a fork, you can also make libev check for a fork in each iteration by
335enabling this flag.</p>
336 <p>This works by calling <code>getpid ()</code> on every iteration of the loop,
337and thus this might slow down your event loop if you do a lot of loop
338iterations and little real work, but is usually not noticeable (on my
339Linux system for example, <code>getpid</code> is actually a simple 5-insn sequence
340without a syscall and thus <i>very</i> fast, but my Linux system also has
341<code>pthread_atfork</code> which is even faster).</p>
342 <p>The big advantage of this flag is that you can forget about fork (and
343forget about forgetting to tell libev about forking) when you use this
344flag.</p>
345 <p>This flag setting cannot be overriden or specified in the <code>LIBEV_FLAGS</code>
346environment variable.</p>
278 </dd> 347 </dd>
279 <dt><code>EVBACKEND_SELECT</code> (value 1, portable select backend)</dt> 348 <dt><code>EVBACKEND_SELECT</code> (value 1, portable select backend)</dt>
280 <dd> 349 <dd>
281 <p>This is your standard select(2) backend. Not <i>completely</i> standard, as 350 <p>This is your standard select(2) backend. Not <i>completely</i> standard, as
282libev tries to roll its own fd_set with no limits on the number of fds, 351libev tries to roll its own fd_set with no limits on the number of fds,
… …
365 <dd> 434 <dd>
366 <p>Similar to <code>ev_default_loop</code>, but always creates a new event loop that is 435 <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 436always 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 437handle signal and child watchers, and attempts to do so will be greeted by
369undefined behaviour (or a failed assertion if assertions are enabled).</p> 438undefined 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> 439 <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); 440<pre> struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);
372 if (!epoller) 441 if (!epoller)
373 fatal (&quot;no epoll found here, maybe it hides under your chair&quot;); 442 fatal (&quot;no epoll found here, maybe it hides under your chair&quot;);
374 443
375</pre> 444</pre>
… …
411 <dt>ev_loop_fork (loop)</dt> 480 <dt>ev_loop_fork (loop)</dt>
412 <dd> 481 <dd>
413 <p>Like <code>ev_default_fork</code>, but acts on an event loop created by 482 <p>Like <code>ev_default_fork</code>, but acts on an event loop created by
414<code>ev_loop_new</code>. Yes, you have to call this on every allocated event loop 483<code>ev_loop_new</code>. Yes, you have to call this on every allocated event loop
415after fork, and how you do this is entirely your own problem.</p> 484after fork, and how you do this is entirely your own problem.</p>
485 </dd>
486 <dt>unsigned int ev_loop_count (loop)</dt>
487 <dd>
488 <p>Returns the count of loop iterations for the loop, which is identical to
489the number of times libev did poll for new events. It starts at <code>0</code> and
490happily wraps around with enough iterations.</p>
491 <p>This value can sometimes be useful as a generation counter of sorts (it
492&quot;ticks&quot; the number of loop iterations), as it roughly corresponds with
493<code>ev_prepare</code> and <code>ev_check</code> calls.</p>
416 </dd> 494 </dd>
417 <dt>unsigned int ev_backend (loop)</dt> 495 <dt>unsigned int ev_backend (loop)</dt>
418 <dd> 496 <dd>
419 <p>Returns one of the <code>EVBACKEND_*</code> flags indicating the event backend in 497 <p>Returns one of the <code>EVBACKEND_*</code> flags indicating the event backend in
420use.</p> 498use.</p>
… …
468 be handled here by queueing them when their watcher gets executed. 546 be handled here by queueing them when their watcher gets executed.
469 - If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK 547 - If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK
470 were used, return, otherwise continue with step *. 548 were used, return, otherwise continue with step *.
471 549
472</pre> 550</pre>
473 <p>Example: queue some jobs and then loop until no events are outsanding 551 <p>Example: Queue some jobs and then loop until no events are outsanding
474anymore.</p> 552anymore.</p>
475<pre> ... queue jobs here, make sure they register event watchers as long 553<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..) 554 ... as they still have work to do (even an idle watcher will do..)
477 ev_loop (my_loop, 0); 555 ev_loop (my_loop, 0);
478 ... jobs done. yeah! 556 ... jobs done. yeah!
… …
497example, libev itself uses this for its internal signal pipe: It is not 575example, 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 576visible 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 577no 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 578way 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> 579libraries. 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> 580 <p>Example: Create a signal watcher, but keep it from keeping <code>ev_loop</code>
503running when nothing else is active.</p> 581running when nothing else is active.</p>
504<pre> struct dv_signal exitsig; 582<pre> struct ev_signal exitsig;
505 ev_signal_init (&amp;exitsig, sig_cb, SIGINT); 583 ev_signal_init (&amp;exitsig, sig_cb, SIGINT);
506 ev_signal_start (myloop, &amp;exitsig); 584 ev_signal_start (loop, &amp;exitsig);
507 evf_unref (myloop); 585 evf_unref (loop);
508 586
509</pre> 587</pre>
510 <p>Example: for some weird reason, unregister the above signal handler again.</p> 588 <p>Example: For some weird reason, unregister the above signal handler again.</p>
511<pre> ev_ref (myloop); 589<pre> ev_ref (loop);
512 ev_signal_stop (myloop, &amp;exitsig); 590 ev_signal_stop (loop, &amp;exitsig);
513 591
514</pre> 592</pre>
515 </dd> 593 </dd>
516</dl> 594</dl>
517 595
596
597
598
599
518</div> 600</div>
519<h1 id="ANATOMY_OF_A_WATCHER">ANATOMY OF A WATCHER</h1><p><a href="#TOP" class="toplink">Top</a></p> 601<h1 id="ANATOMY_OF_A_WATCHER">ANATOMY OF A WATCHER</h1>
520<div id="ANATOMY_OF_A_WATCHER_CONTENT"> 602<div id="ANATOMY_OF_A_WATCHER_CONTENT">
521<p>A watcher is a structure that you create and register to record your 603<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 604interest 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> 605become 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) 606<pre> static void my_cb (struct ev_loop *loop, struct ev_io *w, int revents)
… …
581 </dd> 663 </dd>
582 <dt><code>EV_CHILD</code></dt> 664 <dt><code>EV_CHILD</code></dt>
583 <dd> 665 <dd>
584 <p>The pid specified in the <code>ev_child</code> watcher has received a status change.</p> 666 <p>The pid specified in the <code>ev_child</code> watcher has received a status change.</p>
585 </dd> 667 </dd>
668 <dt><code>EV_STAT</code></dt>
669 <dd>
670 <p>The path specified in the <code>ev_stat</code> watcher changed its attributes somehow.</p>
671 </dd>
586 <dt><code>EV_IDLE</code></dt> 672 <dt><code>EV_IDLE</code></dt>
587 <dd> 673 <dd>
588 <p>The <code>ev_idle</code> watcher has determined that you have nothing better to do.</p> 674 <p>The <code>ev_idle</code> watcher has determined that you have nothing better to do.</p>
589 </dd> 675 </dd>
590 <dt><code>EV_PREPARE</code></dt> 676 <dt><code>EV_PREPARE</code></dt>
… …
595<code>ev_loop</code> has gathered them, but before it invokes any callbacks for any 681<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 682received 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 683many 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 684(for example, a <code>ev_prepare</code> watcher might start an idle watcher to keep
599<code>ev_loop</code> from blocking).</p> 685<code>ev_loop</code> from blocking).</p>
686 </dd>
687 <dt><code>EV_EMBED</code></dt>
688 <dd>
689 <p>The embedded event loop specified in the <code>ev_embed</code> watcher needs attention.</p>
690 </dd>
691 <dt><code>EV_FORK</code></dt>
692 <dd>
693 <p>The event loop has been resumed in the child process after fork (see
694<code>ev_fork</code>).</p>
600 </dd> 695 </dd>
601 <dt><code>EV_ERROR</code></dt> 696 <dt><code>EV_ERROR</code></dt>
602 <dd> 697 <dd>
603 <p>An unspecified error has occured, the watcher has been stopped. This might 698 <p>An unspecified error has occured, the watcher has been stopped. This might
604happen because the watcher could not be properly started because libev 699happen because the watcher could not be properly started because libev
… …
612programs, though, so beware.</p> 707programs, though, so beware.</p>
613 </dd> 708 </dd>
614</dl> 709</dl>
615 710
616</div> 711</div>
617<h2 id="SUMMARY_OF_GENERIC_WATCHER_FUNCTIONS">SUMMARY OF GENERIC WATCHER FUNCTIONS</h2> 712<h2 id="GENERIC_WATCHER_FUNCTIONS">GENERIC WATCHER FUNCTIONS</h2>
618<div id="SUMMARY_OF_GENERIC_WATCHER_FUNCTIONS-2"> 713<div id="GENERIC_WATCHER_FUNCTIONS_CONTENT">
619<p>In the following description, <code>TYPE</code> stands for the watcher type, 714<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> 715e.g. <code>timer</code> for <code>ev_timer</code> watchers and <code>io</code> for <code>ev_io</code> watchers.</p>
621<dl> 716<dl>
622 <dt><code>ev_init</code> (ev_TYPE *watcher, callback)</dt> 717 <dt><code>ev_init</code> (ev_TYPE *watcher, callback)</dt>
623 <dd> 718 <dd>
… …
627the type-specific <code>ev_TYPE_set</code> macro afterwards to initialise the 722the 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 723type-specific parts. For each type there is also a <code>ev_TYPE_init</code> macro
629which rolls both calls into one.</p> 724which rolls both calls into one.</p>
630 <p>You can reinitialise a watcher at any time as long as it has been stopped 725 <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> 726(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, 727 <p>The callback is always of type <code>void (*)(ev_loop *loop, ev_TYPE *watcher,
633int revents)</code>.</p> 728int revents)</code>.</p>
634 </dd> 729 </dd>
635 <dt><code>ev_TYPE_set</code> (ev_TYPE *, [args])</dt> 730 <dt><code>ev_TYPE_set</code> (ev_TYPE *, [args])</dt>
636 <dd> 731 <dd>
637 <p>This macro initialises the type-specific parts of a watcher. You need to 732 <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 769events 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 770is 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 771<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> 772libev (e.g. you cnanot <code>free ()</code> it).</p>
678 </dd> 773 </dd>
679 <dt>callback = ev_cb (ev_TYPE *watcher)</dt> 774 <dt>callback ev_cb (ev_TYPE *watcher)</dt>
680 <dd> 775 <dd>
681 <p>Returns the callback currently set on the watcher.</p> 776 <p>Returns the callback currently set on the watcher.</p>
682 </dd> 777 </dd>
683 <dt>ev_cb_set (ev_TYPE *watcher, callback)</dt> 778 <dt>ev_cb_set (ev_TYPE *watcher, callback)</dt>
684 <dd> 779 <dd>
685 <p>Change the callback. You can change the callback at virtually any time 780 <p>Change the callback. You can change the callback at virtually any time
686(modulo threads).</p> 781(modulo threads).</p>
782 </dd>
783 <dt>ev_set_priority (ev_TYPE *watcher, priority)</dt>
784 <dt>int ev_priority (ev_TYPE *watcher)</dt>
785 <dd>
786 <p>Set and query the priority of the watcher. The priority is a small
787integer between <code>EV_MAXPRI</code> (default: <code>2</code>) and <code>EV_MINPRI</code>
788(default: <code>-2</code>). Pending watchers with higher priority will be invoked
789before watchers with lower priority, but priority will not keep watchers
790from being executed (except for <code>ev_idle</code> watchers).</p>
791 <p>This means that priorities are <i>only</i> used for ordering callback
792invocation after new events have been received. This is useful, for
793example, to reduce latency after idling, or more often, to bind two
794watchers on the same event and make sure one is called first.</p>
795 <p>If you need to suppress invocation when higher priority events are pending
796you need to look at <code>ev_idle</code> watchers, which provide this functionality.</p>
797 <p>The default priority used by watchers when no priority has been set is
798always <code>0</code>, which is supposed to not be too high and not be too low :).</p>
799 <p>Setting a priority outside the range of <code>EV_MINPRI</code> to <code>EV_MAXPRI</code> is
800fine, as long as you do not mind that the priority value you query might
801or might not have been adjusted to be within valid range.</p>
687 </dd> 802 </dd>
688</dl> 803</dl>
689 804
690 805
691 806
… …
716 struct my_io *w = (struct my_io *)w_; 831 struct my_io *w = (struct my_io *)w_;
717 ... 832 ...
718 } 833 }
719 834
720</pre> 835</pre>
721<p>More interesting and less C-conformant ways of catsing your callback type 836<p>More interesting and less C-conformant ways of casting your callback type
722have been omitted....</p> 837instead have been omitted.</p>
838<p>Another common scenario is having some data structure with multiple
839watchers:</p>
840<pre> struct my_biggy
841 {
842 int some_data;
843 ev_timer t1;
844 ev_timer t2;
845 }
723 846
847</pre>
848<p>In this case getting the pointer to <code>my_biggy</code> is a bit more complicated,
849you need to use <code>offsetof</code>:</p>
850<pre> #include &lt;stddef.h&gt;
724 851
852 static void
853 t1_cb (EV_P_ struct ev_timer *w, int revents)
854 {
855 struct my_biggy big = (struct my_biggy *
856 (((char *)w) - offsetof (struct my_biggy, t1));
857 }
725 858
859 static void
860 t2_cb (EV_P_ struct ev_timer *w, int revents)
861 {
862 struct my_biggy big = (struct my_biggy *
863 (((char *)w) - offsetof (struct my_biggy, t2));
864 }
726 865
727 866
867
868
869</pre>
870
728</div> 871</div>
729<h1 id="WATCHER_TYPES">WATCHER TYPES</h1><p><a href="#TOP" class="toplink">Top</a></p> 872<h1 id="WATCHER_TYPES">WATCHER TYPES</h1>
730<div id="WATCHER_TYPES_CONTENT"> 873<div id="WATCHER_TYPES_CONTENT">
731<p>This section describes each watcher in detail, but will not repeat 874<p>This section describes each watcher in detail, but will not repeat
732information given in the last section.</p> 875information given in the last section. Any initialisation/set macros,
876functions and members specific to the watcher type are explained.</p>
877<p>Members are additionally marked with either <i>[read-only]</i>, meaning that,
878while the watcher is active, you can look at the member and expect some
879sensible content, but you must not modify it (you can modify it while the
880watcher is stopped to your hearts content), or <i>[read-write]</i>, which
881means you can expect it to have some sensible content while the watcher
882is active, but you can also modify it. Modifying it may not do something
883sensible or take immediate effect (or do anything at all), but libev will
884not crash or malfunction in any way.</p>
733 885
734 886
735 887
736 888
737 889
738</div> 890</div>
739<h2 id="code_ev_io_code_is_this_file_descrip"><code>ev_io</code> - is this file descriptor readable or writable</h2> 891<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"> 892<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 893<p>I/O watchers check whether a file descriptor is readable or writable
742in each iteration of the event loop (This behaviour is called 894in each iteration of the event loop, or, more precisely, when reading
743level-triggering because you keep receiving events as long as the 895would 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 896some data. This behaviour is called level-triggering because you keep
745act on the event and neither want to receive future events).</p> 897receiving events as long as the condition persists. Remember you can stop
898the watcher if you don't want to act on the event and neither want to
899receive future events.</p>
746<p>In general you can register as many read and/or write event watchers per 900<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 901fd 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 902descriptors to non-blocking mode is also usually a good idea (but not
749required if you know what you are doing).</p> 903required if you know what you are doing).</p>
750<p>You have to be careful with dup'ed file descriptors, though. Some backends 904<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 905(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 906descriptors correctly if you register interest in two or more fds pointing
753to the same underlying file/socket etc. description (that is, they share 907to the same underlying file/socket/etc. description (that is, they share
754the same underlying &quot;file open&quot;).</p> 908the 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 909<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 910(at the time of this writing, this includes only <code>EVBACKEND_SELECT</code> and
757<code>EVBACKEND_POLL</code>).</p> 911<code>EVBACKEND_POLL</code>).</p>
912<p>Another thing you have to watch out for is that it is quite easy to
913receive &quot;spurious&quot; readyness notifications, that is your callback might
914be called with <code>EV_READ</code> but a subsequent <code>read</code>(2) will actually block
915because there is no data. Not only are some backends known to create a
916lot of those (for example solaris ports), it is very easy to get into
917this situation even with a relatively standard program structure. Thus
918it is best to always use non-blocking I/O: An extra <code>read</code>(2) returning
919<code>EAGAIN</code> is far preferable to a program hanging until some data arrives.</p>
920<p>If you cannot run the fd in non-blocking mode (for example you should not
921play around with an Xlib connection), then you have to seperately re-test
922wether a file descriptor is really ready with a known-to-be good interface
923such as poll (fortunately in our Xlib example, Xlib already does this on
924its own, so its quite safe to use).</p>
758<dl> 925<dl>
759 <dt>ev_io_init (ev_io *, callback, int fd, int events)</dt> 926 <dt>ev_io_init (ev_io *, callback, int fd, int events)</dt>
760 <dt>ev_io_set (ev_io *, int fd, int events)</dt> 927 <dt>ev_io_set (ev_io *, int fd, int events)</dt>
761 <dd> 928 <dd>
762 <p>Configures an <code>ev_io</code> watcher. The fd is the file descriptor to rceeive 929 <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 | 930rceeive events for and events is either <code>EV_READ</code>, <code>EV_WRITE</code> or
764EV_WRITE</code> to receive the given events.</p> 931<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 932 </dd>
766epoll and solaris ports) can result in spurious readyness notifications 933 <dt>int fd [read-only]</dt>
767for file descriptors, so you practically need to use non-blocking I/O (and 934 <dd>
768treat callback invocation as hint only), or retest separately with a safe 935 <p>The file descriptor being watched.</p>
769interface before doing I/O (XLib can do this), or force the use of either 936 </dd>
770<code>EVBACKEND_SELECT</code> or <code>EVBACKEND_POLL</code>, which don't suffer from this 937 <dt>int events [read-only]</dt>
771problem. Also note that it is quite easy to have your callback invoked 938 <dd>
772when the readyness condition is no longer valid even when employing 939 <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> 940 </dd>
776</dl> 941</dl>
777<p>Example: call <code>stdin_readable_cb</code> when STDIN_FILENO has become, well 942<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 943readable, but only once. Since it is likely line-buffered, you could
779attempt to read a whole line in the callback:</p> 944attempt to read a whole line in the callback.</p>
780<pre> static void 945<pre> static void
781 stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents) 946 stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents)
782 { 947 {
783 ev_io_stop (loop, w); 948 ev_io_stop (loop, w);
784 .. read from stdin here (or from w-&gt;fd) and haqndle any I/O errors 949 .. read from stdin here (or from w-&gt;fd) and haqndle any I/O errors
… …
795 960
796 961
797</pre> 962</pre>
798 963
799</div> 964</div>
800<h2 id="code_ev_timer_code_relative_and_opti"><code>ev_timer</code> - relative and optionally recurring timeouts</h2> 965<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"> 966<div id="code_ev_timer_code_relative_and_opti-2">
802<p>Timer watchers are simple relative timers that generate an event after a 967<p>Timer watchers are simple relative timers that generate an event after a
803given time, and optionally repeating in regular intervals after that.</p> 968given 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 969<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 970times out after an hour and you reset your system clock to last years
… …
833 </dd> 998 </dd>
834 <dt>ev_timer_again (loop)</dt> 999 <dt>ev_timer_again (loop)</dt>
835 <dd> 1000 <dd>
836 <p>This will act as if the timer timed out and restart it again if it is 1001 <p>This will act as if the timer timed out and restart it again if it is
837repeating. The exact semantics are:</p> 1002repeating. The exact semantics are:</p>
1003 <p>If the timer is pending, its pending status is cleared.</p>
838 <p>If the timer is started but nonrepeating, stop it.</p> 1004 <p>If the timer is started but nonrepeating, stop it (as if it timed out).</p>
839 <p>If the timer is repeating, either start it if necessary (with the repeat 1005 <p>If the timer is repeating, either start it if necessary (with the
840value), or reset the running timer to the repeat value.</p> 1006<code>repeat</code> value), or reset the running timer to the <code>repeat</code> value.</p>
841 <p>This sounds a bit complicated, but here is a useful and typical 1007 <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 1008example: Imagine you have a tcp connection and you want a so-called idle
843timeout, that is, you want to be called when there have been, say, 60 1009timeout, that is, you want to be called when there have been, say, 60
844seconds of inactivity on the socket. The easiest way to do this is to 1010seconds of inactivity on the socket. The easiest way to do this is to
845configure an <code>ev_timer</code> with after=repeat=60 and calling ev_timer_again each 1011configure an <code>ev_timer</code> with a <code>repeat</code> value of <code>60</code> and then call
846time you successfully read or write some data. If you go into an idle 1012<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 1013you go into an idle state where you do not expect data to travel on the
1014socket, you can <code>ev_timer_stop</code> the timer, and <code>ev_timer_again</code> will
848the timer, and again will automatically restart it if need be.</p> 1015automatically restart it if need be.</p>
1016 <p>That means you can ignore the <code>after</code> value and <code>ev_timer_start</code>
1017altogether and only ever use the <code>repeat</code> value and <code>ev_timer_again</code>:</p>
1018<pre> ev_timer_init (timer, callback, 0., 5.);
1019 ev_timer_again (loop, timer);
1020 ...
1021 timer-&gt;again = 17.;
1022 ev_timer_again (loop, timer);
1023 ...
1024 timer-&gt;again = 10.;
1025 ev_timer_again (loop, timer);
1026
1027</pre>
1028 <p>This is more slightly efficient then stopping/starting the timer each time
1029you want to modify its timeout value.</p>
1030 </dd>
1031 <dt>ev_tstamp repeat [read-write]</dt>
1032 <dd>
1033 <p>The current <code>repeat</code> value. Will be used each time the watcher times out
1034or <code>ev_timer_again</code> is called and determines the next timeout (if any),
1035which is also when any modifications are taken into account.</p>
849 </dd> 1036 </dd>
850</dl> 1037</dl>
851<p>Example: create a timer that fires after 60 seconds.</p> 1038<p>Example: Create a timer that fires after 60 seconds.</p>
852<pre> static void 1039<pre> static void
853 one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) 1040 one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents)
854 { 1041 {
855 .. one minute over, w is actually stopped right here 1042 .. one minute over, w is actually stopped right here
856 } 1043 }
… …
858 struct ev_timer mytimer; 1045 struct ev_timer mytimer;
859 ev_timer_init (&amp;mytimer, one_minute_cb, 60., 0.); 1046 ev_timer_init (&amp;mytimer, one_minute_cb, 60., 0.);
860 ev_timer_start (loop, &amp;mytimer); 1047 ev_timer_start (loop, &amp;mytimer);
861 1048
862</pre> 1049</pre>
863<p>Example: create a timeout timer that times out after 10 seconds of 1050<p>Example: Create a timeout timer that times out after 10 seconds of
864inactivity.</p> 1051inactivity.</p>
865<pre> static void 1052<pre> static void
866 timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents) 1053 timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents)
867 { 1054 {
868 .. ten seconds without any activity 1055 .. ten seconds without any activity
… …
881 1068
882 1069
883</pre> 1070</pre>
884 1071
885</div> 1072</div>
886<h2 id="code_ev_periodic_code_to_cron_or_not"><code>ev_periodic</code> - to cron or not to cron</h2> 1073<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"> 1074<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 1075<p>Periodic watchers are also timers of a kind, but they are very versatile
889(and unfortunately a bit complex).</p> 1076(and unfortunately a bit complex).</p>
890<p>Unlike <code>ev_timer</code>'s, they are not based on real time (or relative time) 1077<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 1078but 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 1158 <p>Simply stops and restarts the periodic watcher again. This is only useful
972when you changed some parameters or the reschedule callback would return 1159when 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 1160a different time than the last time it was called (e.g. in a crond like
974program when the crontabs have changed).</p> 1161program when the crontabs have changed).</p>
975 </dd> 1162 </dd>
1163 <dt>ev_tstamp interval [read-write]</dt>
1164 <dd>
1165 <p>The current interval value. Can be modified any time, but changes only
1166take effect when the periodic timer fires or <code>ev_periodic_again</code> is being
1167called.</p>
1168 </dd>
1169 <dt>ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read-write]</dt>
1170 <dd>
1171 <p>The current reschedule callback, or <code>0</code>, if this functionality is
1172switched off. Can be changed any time, but changes only take effect when
1173the periodic timer fires or <code>ev_periodic_again</code> is being called.</p>
1174 </dd>
976</dl> 1175</dl>
977<p>Example: call a callback every hour, or, more precisely, whenever the 1176<p>Example: Call a callback every hour, or, more precisely, whenever the
978system clock is divisible by 3600. The callback invocation times have 1177system clock is divisible by 3600. The callback invocation times have
979potentially a lot of jittering, but good long-term stability.</p> 1178potentially a lot of jittering, but good long-term stability.</p>
980<pre> static void 1179<pre> static void
981 clock_cb (struct ev_loop *loop, struct ev_io *w, int revents) 1180 clock_cb (struct ev_loop *loop, struct ev_io *w, int revents)
982 { 1181 {
… …
986 struct ev_periodic hourly_tick; 1185 struct ev_periodic hourly_tick;
987 ev_periodic_init (&amp;hourly_tick, clock_cb, 0., 3600., 0); 1186 ev_periodic_init (&amp;hourly_tick, clock_cb, 0., 3600., 0);
988 ev_periodic_start (loop, &amp;hourly_tick); 1187 ev_periodic_start (loop, &amp;hourly_tick);
989 1188
990</pre> 1189</pre>
991<p>Example: the same as above, but use a reschedule callback to do it:</p> 1190<p>Example: The same as above, but use a reschedule callback to do it:</p>
992<pre> #include &lt;math.h&gt; 1191<pre> #include &lt;math.h&gt;
993 1192
994 static ev_tstamp 1193 static ev_tstamp
995 my_scheduler_cb (struct ev_periodic *w, ev_tstamp now) 1194 my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)
996 { 1195 {
… …
998 } 1197 }
999 1198
1000 ev_periodic_init (&amp;hourly_tick, clock_cb, 0., 0., my_scheduler_cb); 1199 ev_periodic_init (&amp;hourly_tick, clock_cb, 0., 0., my_scheduler_cb);
1001 1200
1002</pre> 1201</pre>
1003<p>Example: call a callback every hour, starting now:</p> 1202<p>Example: Call a callback every hour, starting now:</p>
1004<pre> struct ev_periodic hourly_tick; 1203<pre> struct ev_periodic hourly_tick;
1005 ev_periodic_init (&amp;hourly_tick, clock_cb, 1204 ev_periodic_init (&amp;hourly_tick, clock_cb,
1006 fmod (ev_now (loop), 3600.), 3600., 0); 1205 fmod (ev_now (loop), 3600.), 3600., 0);
1007 ev_periodic_start (loop, &amp;hourly_tick); 1206 ev_periodic_start (loop, &amp;hourly_tick);
1008 1207
… …
1010 1209
1011 1210
1012</pre> 1211</pre>
1013 1212
1014</div> 1213</div>
1015<h2 id="code_ev_signal_code_signal_me_when_a"><code>ev_signal</code> - signal me when a signal gets signalled</h2> 1214<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"> 1215<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 1216<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 1217signal 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 1218will try it's best to deliver signals synchronously, i.e. as part of the
1020normal event processing, like any other event.</p> 1219normal event processing, like any other event.</p>
… …
1029 <dt>ev_signal_set (ev_signal *, int signum)</dt> 1228 <dt>ev_signal_set (ev_signal *, int signum)</dt>
1030 <dd> 1229 <dd>
1031 <p>Configures the watcher to trigger on the given signal number (usually one 1230 <p>Configures the watcher to trigger on the given signal number (usually one
1032of the <code>SIGxxx</code> constants).</p> 1231of the <code>SIGxxx</code> constants).</p>
1033 </dd> 1232 </dd>
1233 <dt>int signum [read-only]</dt>
1234 <dd>
1235 <p>The signal the watcher watches out for.</p>
1236 </dd>
1034</dl> 1237</dl>
1035 1238
1036 1239
1037 1240
1038 1241
1039 1242
1040</div> 1243</div>
1041<h2 id="code_ev_child_code_wait_for_pid_stat"><code>ev_child</code> - wait for pid status changes</h2> 1244<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"> 1245<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 1246<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> 1247some child status changes (most typically when a child of yours dies).</p>
1045<dl> 1248<dl>
1046 <dt>ev_child_init (ev_child *, callback, int pid)</dt> 1249 <dt>ev_child_init (ev_child *, callback, int pid)</dt>
1047 <dt>ev_child_set (ev_child *, int pid)</dt> 1250 <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 1254at 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 1255the 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 1256<code>waitpid</code> documentation). The <code>rpid</code> member contains the pid of the
1054process causing the status change.</p> 1257process causing the status change.</p>
1055 </dd> 1258 </dd>
1259 <dt>int pid [read-only]</dt>
1260 <dd>
1261 <p>The process id this watcher watches out for, or <code>0</code>, meaning any process id.</p>
1262 </dd>
1263 <dt>int rpid [read-write]</dt>
1264 <dd>
1265 <p>The process id that detected a status change.</p>
1266 </dd>
1267 <dt>int rstatus [read-write]</dt>
1268 <dd>
1269 <p>The process exit/trace status caused by <code>rpid</code> (see your systems
1270<code>waitpid</code> and <code>sys/wait.h</code> documentation for details).</p>
1271 </dd>
1056</dl> 1272</dl>
1057<p>Example: try to exit cleanly on SIGINT and SIGTERM.</p> 1273<p>Example: Try to exit cleanly on SIGINT and SIGTERM.</p>
1058<pre> static void 1274<pre> static void
1059 sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) 1275 sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents)
1060 { 1276 {
1061 ev_unloop (loop, EVUNLOOP_ALL); 1277 ev_unloop (loop, EVUNLOOP_ALL);
1062 } 1278 }
… …
1069 1285
1070 1286
1071</pre> 1287</pre>
1072 1288
1073</div> 1289</div>
1290<h2 id="code_ev_stat_code_did_the_file_attri"><code>ev_stat</code> - did the file attributes just change?</h2>
1291<div id="code_ev_stat_code_did_the_file_attri-2">
1292<p>This watches a filesystem path for attribute changes. That is, it calls
1293<code>stat</code> regularly (or when the OS says it changed) and sees if it changed
1294compared to the last time, invoking the callback if it did.</p>
1295<p>The path does not need to exist: changing from &quot;path exists&quot; to &quot;path does
1296not exist&quot; is a status change like any other. The condition &quot;path does
1297not exist&quot; is signified by the <code>st_nlink</code> field being zero (which is
1298otherwise always forced to be at least one) and all the other fields of
1299the stat buffer having unspecified contents.</p>
1300<p>The path <i>should</i> be absolute and <i>must not</i> end in a slash. If it is
1301relative and your working directory changes, the behaviour is undefined.</p>
1302<p>Since there is no standard to do this, the portable implementation simply
1303calls <code>stat (2)</code> regularly on the path to see if it changed somehow. You
1304can specify a recommended polling interval for this case. If you specify
1305a polling interval of <code>0</code> (highly recommended!) then a <i>suitable,
1306unspecified default</i> value will be used (which you can expect to be around
1307five seconds, although this might change dynamically). Libev will also
1308impose a minimum interval which is currently around <code>0.1</code>, but thats
1309usually overkill.</p>
1310<p>This watcher type is not meant for massive numbers of stat watchers,
1311as even with OS-supported change notifications, this can be
1312resource-intensive.</p>
1313<p>At the time of this writing, only the Linux inotify interface is
1314implemented (implementing kqueue support is left as an exercise for the
1315reader). Inotify will be used to give hints only and should not change the
1316semantics of <code>ev_stat</code> watchers, which means that libev sometimes needs
1317to fall back to regular polling again even with inotify, but changes are
1318usually detected immediately, and if the file exists there will be no
1319polling.</p>
1320<dl>
1321 <dt>ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)</dt>
1322 <dt>ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)</dt>
1323 <dd>
1324 <p>Configures the watcher to wait for status changes of the given
1325<code>path</code>. The <code>interval</code> is a hint on how quickly a change is expected to
1326be detected and should normally be specified as <code>0</code> to let libev choose
1327a suitable value. The memory pointed to by <code>path</code> must point to the same
1328path for as long as the watcher is active.</p>
1329 <p>The callback will be receive <code>EV_STAT</code> when a change was detected,
1330relative to the attributes at the time the watcher was started (or the
1331last change was detected).</p>
1332 </dd>
1333 <dt>ev_stat_stat (ev_stat *)</dt>
1334 <dd>
1335 <p>Updates the stat buffer immediately with new values. If you change the
1336watched path in your callback, you could call this fucntion to avoid
1337detecting this change (while introducing a race condition). Can also be
1338useful simply to find out the new values.</p>
1339 </dd>
1340 <dt>ev_statdata attr [read-only]</dt>
1341 <dd>
1342 <p>The most-recently detected attributes of the file. Although the type is of
1343<code>ev_statdata</code>, this is usually the (or one of the) <code>struct stat</code> types
1344suitable for your system. If the <code>st_nlink</code> member is <code>0</code>, then there
1345was some error while <code>stat</code>ing the file.</p>
1346 </dd>
1347 <dt>ev_statdata prev [read-only]</dt>
1348 <dd>
1349 <p>The previous attributes of the file. The callback gets invoked whenever
1350<code>prev</code> != <code>attr</code>.</p>
1351 </dd>
1352 <dt>ev_tstamp interval [read-only]</dt>
1353 <dd>
1354 <p>The specified interval.</p>
1355 </dd>
1356 <dt>const char *path [read-only]</dt>
1357 <dd>
1358 <p>The filesystem path that is being watched.</p>
1359 </dd>
1360</dl>
1361<p>Example: Watch <code>/etc/passwd</code> for attribute changes.</p>
1362<pre> static void
1363 passwd_cb (struct ev_loop *loop, ev_stat *w, int revents)
1364 {
1365 /* /etc/passwd changed in some way */
1366 if (w-&gt;attr.st_nlink)
1367 {
1368 printf (&quot;passwd current size %ld\n&quot;, (long)w-&gt;attr.st_size);
1369 printf (&quot;passwd current atime %ld\n&quot;, (long)w-&gt;attr.st_mtime);
1370 printf (&quot;passwd current mtime %ld\n&quot;, (long)w-&gt;attr.st_mtime);
1371 }
1372 else
1373 /* you shalt not abuse printf for puts */
1374 puts (&quot;wow, /etc/passwd is not there, expect problems. &quot;
1375 &quot;if this is windows, they already arrived\n&quot;);
1376 }
1377
1378 ...
1379 ev_stat passwd;
1380
1381 ev_stat_init (&amp;passwd, passwd_cb, &quot;/etc/passwd&quot;);
1382 ev_stat_start (loop, &amp;passwd);
1383
1384
1385
1386
1387</pre>
1388
1389</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> 1390<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"> 1391<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 1392<p>Idle watchers trigger events when no other events of the same or higher
1077(prepare, check and other idle watchers do not count). That is, as long 1393priority are pending (prepare, check and other idle watchers do not
1078as your process is busy handling sockets or timeouts (or even signals, 1394count).</p>
1079imagine) it will not be triggered. But when your process is idle all idle 1395<p>That is, as long as your process is busy handling sockets or timeouts
1080watchers are being called again and again, once per event loop iteration - 1396(or even signals, imagine) of the same or higher priority it will not be
1397triggered. But when your process is idle (or only lower-priority watchers
1398are pending), the idle watchers are being called once per event loop
1081until stopped, that is, or your process receives more events and becomes 1399iteration - until stopped, that is, or your process receives more events
1082busy.</p> 1400and becomes busy again with higher priority stuff.</p>
1083<p>The most noteworthy effect is that as long as any idle watchers are 1401<p>The most noteworthy effect is that as long as any idle watchers are
1084active, the process will not block when waiting for new events.</p> 1402active, the process will not block when waiting for new events.</p>
1085<p>Apart from keeping your process non-blocking (which is a useful 1403<p>Apart from keeping your process non-blocking (which is a useful
1086effect on its own sometimes), idle watchers are a good place to do 1404effect on its own sometimes), idle watchers are a good place to do
1087&quot;pseudo-background processing&quot;, or delay processing stuff to after the 1405&quot;pseudo-background processing&quot;, or delay processing stuff to after the
… …
1092 <p>Initialises and configures the idle watcher - it has no parameters of any 1410 <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, 1411kind. There is a <code>ev_idle_set</code> macro, but using it is utterly pointless,
1094believe me.</p> 1412believe me.</p>
1095 </dd> 1413 </dd>
1096</dl> 1414</dl>
1097<p>Example: dynamically allocate an <code>ev_idle</code>, start it, and in the 1415<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> 1416callback, free it. Also, use no error checking, as usual.</p>
1099<pre> static void 1417<pre> static void
1100 idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents) 1418 idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents)
1101 { 1419 {
1102 free (w); 1420 free (w);
1103 // now do something you wanted to do when the program has 1421 // now do something you wanted to do when the program has
… …
1112 1430
1113 1431
1114</pre> 1432</pre>
1115 1433
1116</div> 1434</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> 1435<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"> 1436<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: 1437<p>Prepare and check watchers are usually (but not always) used in tandem:
1120prepare watchers get invoked before the process blocks and check watchers 1438prepare watchers get invoked before the process blocks and check watchers
1121afterwards.</p> 1439afterwards.</p>
1440<p>You <i>must not</i> call <code>ev_loop</code> or similar functions that enter
1441the current event loop from either <code>ev_prepare</code> or <code>ev_check</code>
1442watchers. Other loops than the current one are fine, however. The
1443rationale behind this is that you do not need to check for recursion in
1444those watchers, i.e. the sequence will always be <code>ev_prepare</code>, blocking,
1445<code>ev_check</code> so if you have one watcher of each kind they will always be
1446called in pairs bracketing the blocking call.</p>
1122<p>Their main purpose is to integrate other event mechanisms into libev and 1447<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 1448their use is somewhat advanced. This could be used, for example, to track
1124variable changes, implement your own watchers, integrate net-snmp or a 1449variable changes, implement your own watchers, integrate net-snmp or a
1125coroutine library and lots more.</p> 1450coroutine library and lots more. They are also occasionally useful if
1451you cache some data and want to flush it before blocking (for example,
1452in X programs you might want to do an <code>XFlush ()</code> in an <code>ev_prepare</code>
1453watcher).</p>
1126<p>This is done by examining in each prepare call which file descriptors need 1454<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 1455to 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 1456them 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 1457provide just this functionality). Then, in the check watcher you check for
1130any events that occured (by checking the pending status of all watchers 1458any events that occured (by checking the pending status of all watchers
… …
1146 <p>Initialises and configures the prepare or check watcher - they have no 1474 <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> 1475parameters 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> 1476macros, but using them is utterly, utterly and completely pointless.</p>
1149 </dd> 1477 </dd>
1150</dl> 1478</dl>
1151<p>Example: *TODO*.</p> 1479<p>Example: To include a library such as adns, you would add IO watchers
1480and a timeout watcher in a prepare handler, as required by libadns, and
1481in a check watcher, destroy them and call into libadns. What follows is
1482pseudo-code only of course:</p>
1483<pre> static ev_io iow [nfd];
1484 static ev_timer tw;
1152 1485
1486 static void
1487 io_cb (ev_loop *loop, ev_io *w, int revents)
1488 {
1489 // set the relevant poll flags
1490 // could also call adns_processreadable etc. here
1491 struct pollfd *fd = (struct pollfd *)w-&gt;data;
1492 if (revents &amp; EV_READ ) fd-&gt;revents |= fd-&gt;events &amp; POLLIN;
1493 if (revents &amp; EV_WRITE) fd-&gt;revents |= fd-&gt;events &amp; POLLOUT;
1494 }
1153 1495
1496 // create io watchers for each fd and a timer before blocking
1497 static void
1498 adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents)
1499 {
1500 int timeout = 3600000;
1501 struct pollfd fds [nfd];
1502 // actual code will need to loop here and realloc etc.
1503 adns_beforepoll (ads, fds, &amp;nfd, &amp;timeout, timeval_from (ev_time ()));
1154 1504
1505 /* the callback is illegal, but won't be called as we stop during check */
1506 ev_timer_init (&amp;tw, 0, timeout * 1e-3);
1507 ev_timer_start (loop, &amp;tw);
1155 1508
1509 // create on ev_io per pollfd
1510 for (int i = 0; i &lt; nfd; ++i)
1511 {
1512 ev_io_init (iow + i, io_cb, fds [i].fd,
1513 ((fds [i].events &amp; POLLIN ? EV_READ : 0)
1514 | (fds [i].events &amp; POLLOUT ? EV_WRITE : 0)));
1156 1515
1516 fds [i].revents = 0;
1517 iow [i].data = fds + i;
1518 ev_io_start (loop, iow + i);
1519 }
1520 }
1521
1522 // stop all watchers after blocking
1523 static void
1524 adns_check_cb (ev_loop *loop, ev_check *w, int revents)
1525 {
1526 ev_timer_stop (loop, &amp;tw);
1527
1528 for (int i = 0; i &lt; nfd; ++i)
1529 ev_io_stop (loop, iow + i);
1530
1531 adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));
1532 }
1533
1534
1535
1536
1537</pre>
1538
1157</div> 1539</div>
1158<h2 id="code_ev_embed_code_when_one_backend_"><code>ev_embed</code> - when one backend isn't enough</h2> 1540<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"> 1541<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 1542<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 1543into 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 1544loop, other types of watchers might be handled in a delayed or incorrect
1163fashion and must not be used).</p> 1545fashion and must not be used).</p>
… …
1231 <dd> 1613 <dd>
1232 <p>Make a single, non-blocking sweep over the embedded loop. This works 1614 <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 1615similarly to <code>ev_loop (embedded_loop, EVLOOP_NONBLOCK)</code>, but in the most
1234apropriate way for embedded loops.</p> 1616apropriate way for embedded loops.</p>
1235 </dd> 1617 </dd>
1618 <dt>struct ev_loop *loop [read-only]</dt>
1619 <dd>
1620 <p>The embedded event loop.</p>
1621 </dd>
1236</dl> 1622</dl>
1237 1623
1238 1624
1239 1625
1240 1626
1241 1627
1242</div> 1628</div>
1243<h1 id="OTHER_FUNCTIONS">OTHER FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p> 1629<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>
1630<div id="code_ev_fork_code_the_audacity_to_re-2">
1631<p>Fork watchers are called when a <code>fork ()</code> was detected (usually because
1632whoever is a good citizen cared to tell libev about it by calling
1633<code>ev_default_fork</code> or <code>ev_loop_fork</code>). The invocation is done before the
1634event loop blocks next and before <code>ev_check</code> watchers are being called,
1635and only in the child after the fork. If whoever good citizen calling
1636<code>ev_default_fork</code> cheats and calls it in the wrong process, the fork
1637handlers will be invoked, too, of course.</p>
1638<dl>
1639 <dt>ev_fork_init (ev_signal *, callback)</dt>
1640 <dd>
1641 <p>Initialises and configures the fork watcher - it has no parameters of any
1642kind. There is a <code>ev_fork_set</code> macro, but using it is utterly pointless,
1643believe me.</p>
1644 </dd>
1645</dl>
1646
1647
1648
1649
1650
1651</div>
1652<h1 id="OTHER_FUNCTIONS">OTHER FUNCTIONS</h1>
1244<div id="OTHER_FUNCTIONS_CONTENT"> 1653<div id="OTHER_FUNCTIONS_CONTENT">
1245<p>There are some other functions of possible interest. Described. Here. Now.</p> 1654<p>There are some other functions of possible interest. Described. Here. Now.</p>
1246<dl> 1655<dl>
1247 <dt>ev_once (loop, int fd, int events, ev_tstamp timeout, callback)</dt> 1656 <dt>ev_once (loop, int fd, int events, ev_tstamp timeout, callback)</dt>
1248 <dd> 1657 <dd>
… …
1295 1704
1296 1705
1297 1706
1298 1707
1299</div> 1708</div>
1300<h1 id="LIBEVENT_EMULATION">LIBEVENT EMULATION</h1><p><a href="#TOP" class="toplink">Top</a></p> 1709<h1 id="LIBEVENT_EMULATION">LIBEVENT EMULATION</h1>
1301<div id="LIBEVENT_EMULATION_CONTENT"> 1710<div id="LIBEVENT_EMULATION_CONTENT">
1302<p>Libev offers a compatibility emulation layer for libevent. It cannot 1711<p>Libev offers a compatibility emulation layer for libevent. It cannot
1303emulate the internals of libevent, so here are some usage hints:</p> 1712emulate the internals of libevent, so here are some usage hints:</p>
1304<dl> 1713<dl>
1305 <dt>* Use it by including &lt;event.h&gt;, as usual.</dt> 1714 <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 1724 <dt>* The libev emulation is <i>not</i> ABI compatible to libevent, you need
1316to use the libev header file and library.</dt> 1725to use the libev header file and library.</dt>
1317</dl> 1726</dl>
1318 1727
1319</div> 1728</div>
1320<h1 id="C_SUPPORT">C++ SUPPORT</h1><p><a href="#TOP" class="toplink">Top</a></p> 1729<h1 id="C_SUPPORT">C++ SUPPORT</h1>
1321<div id="C_SUPPORT_CONTENT"> 1730<div id="C_SUPPORT_CONTENT">
1322<p>Libev comes with some simplistic wrapper classes for C++ that mainly allow 1731<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 1732you to use some convinience methods to start/stop watchers and also change
1324the callback model to a model using method callbacks on objects.</p> 1733the callback model to a model using method callbacks on objects.</p>
1325<p>To use it,</p> 1734<p>To use it,</p>
… …
1389 </dd> 1798 </dd>
1390 <dt>w-&gt;sweep () <code>ev::embed</code> only</dt> 1799 <dt>w-&gt;sweep () <code>ev::embed</code> only</dt>
1391 <dd> 1800 <dd>
1392 <p>Invokes <code>ev_embed_sweep</code>.</p> 1801 <p>Invokes <code>ev_embed_sweep</code>.</p>
1393 </dd> 1802 </dd>
1803 <dt>w-&gt;update () <code>ev::stat</code> only</dt>
1804 <dd>
1805 <p>Invokes <code>ev_stat_stat</code>.</p>
1806 </dd>
1394 </dl> 1807 </dl>
1395 </p> 1808 </p>
1396 </dd> 1809 </dd>
1397</dl> 1810</dl>
1398<p>Example: Define a class with an IO and idle watcher, start one of them in 1811<p>Example: Define a class with an IO and idle watcher, start one of them in
… …
1410 idle (this, &amp;myclass::idle_cb) 1823 idle (this, &amp;myclass::idle_cb)
1411 { 1824 {
1412 io.start (fd, ev::READ); 1825 io.start (fd, ev::READ);
1413 } 1826 }
1414 1827
1415</pre>
1416 1828
1829
1830
1831</pre>
1832
1417</div> 1833</div>
1418<h1 id="EMBEDDING">EMBEDDING</h1><p><a href="#TOP" class="toplink">Top</a></p> 1834<h1 id="MACRO_MAGIC">MACRO MAGIC</h1>
1835<div id="MACRO_MAGIC_CONTENT">
1836<p>Libev can be compiled with a variety of options, the most fundemantal is
1837<code>EV_MULTIPLICITY</code>. This option determines wether (most) functions and
1838callbacks have an initial <code>struct ev_loop *</code> argument.</p>
1839<p>To make it easier to write programs that cope with either variant, the
1840following macros are defined:</p>
1841<dl>
1842 <dt><code>EV_A</code>, <code>EV_A_</code></dt>
1843 <dd>
1844 <p>This provides the loop <i>argument</i> for functions, if one is required (&quot;ev
1845loop argument&quot;). The <code>EV_A</code> form is used when this is the sole argument,
1846<code>EV_A_</code> is used when other arguments are following. Example:</p>
1847<pre> ev_unref (EV_A);
1848 ev_timer_add (EV_A_ watcher);
1849 ev_loop (EV_A_ 0);
1850
1851</pre>
1852 <p>It assumes the variable <code>loop</code> of type <code>struct ev_loop *</code> is in scope,
1853which is often provided by the following macro.</p>
1854 </dd>
1855 <dt><code>EV_P</code>, <code>EV_P_</code></dt>
1856 <dd>
1857 <p>This provides the loop <i>parameter</i> for functions, if one is required (&quot;ev
1858loop parameter&quot;). The <code>EV_P</code> form is used when this is the sole parameter,
1859<code>EV_P_</code> is used when other parameters are following. Example:</p>
1860<pre> // this is how ev_unref is being declared
1861 static void ev_unref (EV_P);
1862
1863 // this is how you can declare your typical callback
1864 static void cb (EV_P_ ev_timer *w, int revents)
1865
1866</pre>
1867 <p>It declares a parameter <code>loop</code> of type <code>struct ev_loop *</code>, quite
1868suitable for use with <code>EV_A</code>.</p>
1869 </dd>
1870 <dt><code>EV_DEFAULT</code>, <code>EV_DEFAULT_</code></dt>
1871 <dd>
1872 <p>Similar to the other two macros, this gives you the value of the default
1873loop, if multiple loops are supported (&quot;ev loop default&quot;).</p>
1874 </dd>
1875</dl>
1876<p>Example: Declare and initialise a check watcher, utilising the above
1877macros so it will work regardless of wether multiple loops are supported
1878or not.</p>
1879<pre> static void
1880 check_cb (EV_P_ ev_timer *w, int revents)
1881 {
1882 ev_check_stop (EV_A_ w);
1883 }
1884
1885 ev_check check;
1886 ev_check_init (&amp;check, check_cb);
1887 ev_check_start (EV_DEFAULT_ &amp;check);
1888 ev_loop (EV_DEFAULT_ 0);
1889
1890</pre>
1891
1892</div>
1893<h1 id="EMBEDDING">EMBEDDING</h1>
1419<div id="EMBEDDING_CONTENT"> 1894<div id="EMBEDDING_CONTENT">
1420<p>Libev can (and often is) directly embedded into host 1895<p>Libev can (and often is) directly embedded into host
1421applications. Examples of applications that embed it include the Deliantra 1896applications. Examples of applications that embed it include the Deliantra
1422Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe) 1897Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe)
1423and rxvt-unicode.</p> 1898and rxvt-unicode.</p>
… …
1460 ev_vars.h 1935 ev_vars.h
1461 ev_wrap.h 1936 ev_wrap.h
1462 1937
1463 ev_win32.c required on win32 platforms only 1938 ev_win32.c required on win32 platforms only
1464 1939
1465 ev_select.c only when select backend is enabled (which is is by default) 1940 ev_select.c only when select backend is enabled (which is enabled by default)
1466 ev_poll.c only when poll backend is enabled (disabled by default) 1941 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) 1942 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) 1943 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) 1944 ev_port.c only when the solaris port backend is enabled (disabled by default)
1470 1945
1471</pre> 1946</pre>
1472<p><cite>ev.c</cite> includes the backend files directly when enabled, so you only need 1947<p><cite>ev.c</cite> includes the backend files directly when enabled, so you only need
1473to compile a single file.</p> 1948to compile this single file.</p>
1474 1949
1475</div> 1950</div>
1476<h3 id="LIBEVENT_COMPATIBILITY_API">LIBEVENT COMPATIBILITY API</h3> 1951<h3 id="LIBEVENT_COMPATIBILITY_API">LIBEVENT COMPATIBILITY API</h3>
1477<div id="LIBEVENT_COMPATIBILITY_API_CONTENT"> 1952<div id="LIBEVENT_COMPATIBILITY_API_CONTENT">
1478<p>To include the libevent compatibility API, also include:</p> 1953<p>To include the libevent compatibility API, also include:</p>
… …
1493</div> 1968</div>
1494<h3 id="AUTOCONF_SUPPORT">AUTOCONF SUPPORT</h3> 1969<h3 id="AUTOCONF_SUPPORT">AUTOCONF SUPPORT</h3>
1495<div id="AUTOCONF_SUPPORT_CONTENT"> 1970<div id="AUTOCONF_SUPPORT_CONTENT">
1496<p>Instead of using <code>EV_STANDALONE=1</code> and providing your config in 1971<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 1972whatever 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 1973<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> 1974include <cite>config.h</cite> and configure itself accordingly.</p>
1500<p>For this of course you need the m4 file:</p> 1975<p>For this of course you need the m4 file:</p>
1501<pre> libev.m4 1976<pre> libev.m4
1502 1977
1503</pre> 1978</pre>
1504 1979
… …
1597 </dd> 2072 </dd>
1598 <dt>EV_USE_DEVPOLL</dt> 2073 <dt>EV_USE_DEVPOLL</dt>
1599 <dd> 2074 <dd>
1600 <p>reserved for future expansion, works like the USE symbols above.</p> 2075 <p>reserved for future expansion, works like the USE symbols above.</p>
1601 </dd> 2076 </dd>
2077 <dt>EV_USE_INOTIFY</dt>
2078 <dd>
2079 <p>If defined to be <code>1</code>, libev will compile in support for the Linux inotify
2080interface to speed up <code>ev_stat</code> watchers. Its actual availability will
2081be detected at runtime.</p>
2082 </dd>
1602 <dt>EV_H</dt> 2083 <dt>EV_H</dt>
1603 <dd> 2084 <dd>
1604 <p>The name of the <cite>ev.h</cite> header file used to include it. The default if 2085 <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 2086undefined 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
1606can be used to virtually rename the <cite>ev.h</cite> header file in case of conflicts.</p> 2087can be used to virtually rename the <cite>ev.h</cite> header file in case of conflicts.</p>
… …
1629will have the <code>struct ev_loop *</code> as first argument, and you can create 2110will have the <code>struct ev_loop *</code> as first argument, and you can create
1630additional independent event loops. Otherwise there will be no support 2111additional independent event loops. Otherwise there will be no support
1631for multiple event loops and there is no first event loop pointer 2112for multiple event loops and there is no first event loop pointer
1632argument. Instead, all functions act on the single default loop.</p> 2113argument. Instead, all functions act on the single default loop.</p>
1633 </dd> 2114 </dd>
1634 <dt>EV_PERIODICS</dt> 2115 <dt>EV_PERIODIC_ENABLE</dt>
1635 <dd> 2116 <dd>
1636 <p>If undefined or defined to be <code>1</code>, then periodic timers are supported, 2117 <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> 2118defined to be <code>0</code>, then they are not. Disabling them saves a few kB of
2119code.</p>
2120 </dd>
2121 <dt>EV_IDLE_ENABLE</dt>
2122 <dd>
2123 <p>If undefined or defined to be <code>1</code>, then idle watchers are supported. If
2124defined to be <code>0</code>, then they are not. Disabling them saves a few kB of
2125code.</p>
2126 </dd>
2127 <dt>EV_EMBED_ENABLE</dt>
2128 <dd>
2129 <p>If undefined or defined to be <code>1</code>, then embed watchers are supported. If
2130defined to be <code>0</code>, then they are not.</p>
2131 </dd>
2132 <dt>EV_STAT_ENABLE</dt>
2133 <dd>
2134 <p>If undefined or defined to be <code>1</code>, then stat watchers are supported. If
2135defined to be <code>0</code>, then they are not.</p>
2136 </dd>
2137 <dt>EV_FORK_ENABLE</dt>
2138 <dd>
2139 <p>If undefined or defined to be <code>1</code>, then fork watchers are supported. If
2140defined to be <code>0</code>, then they are not.</p>
2141 </dd>
2142 <dt>EV_MINIMAL</dt>
2143 <dd>
2144 <p>If you need to shave off some kilobytes of code at the expense of some
2145speed, define this symbol to <code>1</code>. Currently only used for gcc to override
2146some inlining decisions, saves roughly 30% codesize of amd64.</p>
2147 </dd>
2148 <dt>EV_PID_HASHSIZE</dt>
2149 <dd>
2150 <p><code>ev_child</code> watchers use a small hash table to distribute workload by
2151pid. The default size is <code>16</code> (or <code>1</code> with <code>EV_MINIMAL</code>), usually more
2152than enough. If you need to manage thousands of children you might want to
2153increase this value (<i>must</i> be a power of two).</p>
2154 </dd>
2155 <dt>EV_INOTIFY_HASHSIZE</dt>
2156 <dd>
2157 <p><code>ev_staz</code> watchers use a small hash table to distribute workload by
2158inotify watch id. The default size is <code>16</code> (or <code>1</code> with <code>EV_MINIMAL</code>),
2159usually more than enough. If you need to manage thousands of <code>ev_stat</code>
2160watchers you might want to increase this value (<i>must</i> be a power of
2161two).</p>
1638 </dd> 2162 </dd>
1639 <dt>EV_COMMON</dt> 2163 <dt>EV_COMMON</dt>
1640 <dd> 2164 <dd>
1641 <p>By default, all watchers have a <code>void *data</code> member. By redefining 2165 <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 2166this macro to a something else you can include more and other types of
… …
1647 SV *self; /* contains this struct */ \ 2171 SV *self; /* contains this struct */ \
1648 SV *cb_sv, *fh /* note no trailing &quot;;&quot; */ 2172 SV *cb_sv, *fh /* note no trailing &quot;;&quot; */
1649 2173
1650</pre> 2174</pre>
1651 </dd> 2175 </dd>
1652 <dt>EV_CB_DECLARE(type)</dt> 2176 <dt>EV_CB_DECLARE (type)</dt>
1653 <dt>EV_CB_INVOKE(watcher,revents)</dt> 2177 <dt>EV_CB_INVOKE (watcher, revents)</dt>
1654 <dt>ev_set_cb(ev,cb)</dt> 2178 <dt>ev_set_cb (ev, cb)</dt>
1655 <dd> 2179 <dd>
1656 <p>Can be used to change the callback member declaration in each watcher, 2180 <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 2181and 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 2182definition and a statement, respectively. See the <cite>ev.v</cite> header file for
1659their default definitions. One possible use for overriding these is to 2183their 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 2184avoid the <code>struct ev_loop *</code> as first argument in all cases, or to use
1661calls instead of plain function calls in C++.</p> 2185method calls instead of plain function calls in C++.</p>
1662 2186
1663</div> 2187</div>
1664<h2 id="EXAMPLES">EXAMPLES</h2> 2188<h2 id="EXAMPLES">EXAMPLES</h2>
1665<div id="EXAMPLES_CONTENT"> 2189<div id="EXAMPLES_CONTENT">
1666 <p>For a real-world example of a program the includes libev 2190 <p>For a real-world example of a program the includes libev
… …
1669the <cite>libev/</cite> subdirectory and includes them in the <cite>EV/EVAPI.h</cite> (public 2193the <cite>libev/</cite> subdirectory and includes them in the <cite>EV/EVAPI.h</cite> (public
1670interface) and <cite>EV.xs</cite> (implementation) files. Only the <cite>EV.xs</cite> file 2194interface) and <cite>EV.xs</cite> (implementation) files. Only the <cite>EV.xs</cite> file
1671will be compiled. It is pretty complex because it provides its own header 2195will be compiled. It is pretty complex because it provides its own header
1672file.</p> 2196file.</p>
1673 <p>The usage in rxvt-unicode is simpler. It has a <cite>ev_cpp.h</cite> header file 2197 <p>The usage in rxvt-unicode is simpler. It has a <cite>ev_cpp.h</cite> header file
1674that everybody includes and which overrides some autoconf choices:</p> 2198that everybody includes and which overrides some configure choices:</p>
2199<pre> #define EV_MINIMAL 1
1675<pre> #define EV_USE_POLL 0 2200 #define EV_USE_POLL 0
1676 #define EV_MULTIPLICITY 0 2201 #define EV_MULTIPLICITY 0
1677 #define EV_PERIODICS 0 2202 #define EV_PERIODIC_ENABLE 0
2203 #define EV_STAT_ENABLE 0
2204 #define EV_FORK_ENABLE 0
1678 #define EV_CONFIG_H &lt;config.h&gt; 2205 #define EV_CONFIG_H &lt;config.h&gt;
2206 #define EV_MINPRI 0
2207 #define EV_MAXPRI 0
1679 2208
1680 #include &quot;ev++.h&quot; 2209 #include &quot;ev++.h&quot;
1681 2210
1682</pre> 2211</pre>
1683 <p>And a <cite>ev_cpp.C</cite> implementation file that contains libev proper and is compiled:</p> 2212 <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; 2213<pre> #include &quot;ev_cpp.h&quot;
1685 #include &quot;ev.c&quot; 2214 #include &quot;ev.c&quot;
1686 2215
1687</pre>
1688 2216
2217
2218
2219</pre>
2220
1689</div> 2221</div>
1690<h1 id="AUTHOR">AUTHOR</h1><p><a href="#TOP" class="toplink">Top</a></p> 2222<h1 id="COMPLEXITIES">COMPLEXITIES</h1>
2223<div id="COMPLEXITIES_CONTENT">
2224 <p>In this section the complexities of (many of) the algorithms used inside
2225libev will be explained. For complexity discussions about backends see the
2226documentation for <code>ev_default_init</code>.</p>
2227 <p>
2228 <dl>
2229 <dt>Starting and stopping timer/periodic watchers: O(log skipped_other_timers)</dt>
2230 <dt>Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)</dt>
2231 <dt>Starting io/check/prepare/idle/signal/child watchers: O(1)</dt>
2232 <dt>Stopping check/prepare/idle watchers: O(1)</dt>
2233 <dt>Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))</dt>
2234 <dt>Finding the next timer per loop iteration: O(1)</dt>
2235 <dt>Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)</dt>
2236 <dt>Activating one watcher: O(1)</dt>
2237 </dl>
2238 </p>
2239
2240
2241
2242
2243
2244</div>
2245<h1 id="AUTHOR">AUTHOR</h1>
1691<div id="AUTHOR_CONTENT"> 2246<div id="AUTHOR_CONTENT">
1692 <p>Marc Lehmann &lt;libev@schmorp.de&gt;.</p> 2247 <p>Marc Lehmann &lt;libev@schmorp.de&gt;.</p>
1693 2248
1694</div> 2249</div>
1695</div></body> 2250</div></body>

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