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4<head> 4<head>
5 <title>libev</title> 5 <title>libev</title>
6 <meta name="description" content="Pod documentation for libev" /> 6 <meta name="description" content="Pod documentation for libev" />
7 <meta name="inputfile" content="&lt;standard input&gt;" /> 7 <meta name="inputfile" content="&lt;standard input&gt;" />
8 <meta name="outputfile" content="&lt;standard output&gt;" /> 8 <meta name="outputfile" content="&lt;standard output&gt;" />
9 <meta name="created" content="Tue Nov 27 20:23:27 2007" /> 9 <meta name="created" content="Wed Dec 12 18:55:28 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>
… …
26<ul><li><a href="#GENERIC_WATCHER_FUNCTIONS">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>
33<ul><li><a href="#The_special_problem_of_disappearing_">The special problem of disappearing file descriptors</a></li>
34<li><a href="#Watcher_Specific_Functions">Watcher-Specific Functions</a></li>
35</ul>
36</li>
32<li><a href="#code_ev_timer_code_relative_and_opti"><code>ev_timer</code> - relative and optionally repeating timeouts</a></li> 37<li><a href="#code_ev_timer_code_relative_and_opti"><code>ev_timer</code> - relative and optionally repeating timeouts</a>
38<ul><li><a href="#Watcher_Specific_Functions_and_Data_">Watcher-Specific Functions and Data Members</a></li>
39</ul>
40</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> 41<li><a href="#code_ev_periodic_code_to_cron_or_not"><code>ev_periodic</code> - to cron or not to cron?</a>
42<ul><li><a href="#Watcher_Specific_Functions_and_Data_-3">Watcher-Specific Functions and Data Members</a></li>
43</ul>
44</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> 45<li><a href="#code_ev_signal_code_signal_me_when_a"><code>ev_signal</code> - signal me when a signal gets signalled!</a>
46<ul><li><a href="#Watcher_Specific_Functions_and_Data_-4">Watcher-Specific Functions and Data Members</a></li>
47</ul>
48</li>
35<li><a href="#code_ev_child_code_watch_out_for_pro"><code>ev_child</code> - watch out for process status changes</a></li> 49<li><a href="#code_ev_child_code_watch_out_for_pro"><code>ev_child</code> - watch out for process status changes</a>
50<ul><li><a href="#Watcher_Specific_Functions_and_Data_-5">Watcher-Specific Functions and Data Members</a></li>
51</ul>
52</li>
36<li><a href="#code_ev_stat_code_did_the_file_attri"><code>ev_stat</code> - did the file attributes just change?</a></li> 53<li><a href="#code_ev_stat_code_did_the_file_attri"><code>ev_stat</code> - did the file attributes just change?</a>
54<ul><li><a href="#Watcher_Specific_Functions_and_Data_-6">Watcher-Specific Functions and Data Members</a></li>
55</ul>
56</li>
37<li><a href="#code_ev_idle_code_when_you_ve_got_no"><code>ev_idle</code> - when you've got nothing better to do...</a></li> 57<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>
58<ul><li><a href="#Watcher_Specific_Functions_and_Data_-7">Watcher-Specific Functions and Data Members</a></li>
59</ul>
60</li>
38<li><a href="#code_ev_prepare_code_and_code_ev_che"><code>ev_prepare</code> and <code>ev_check</code> - customise your event loop!</a></li> 61<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>
62<ul><li><a href="#Watcher_Specific_Functions_and_Data_-8">Watcher-Specific Functions and Data Members</a></li>
63</ul>
64</li>
39<li><a href="#code_ev_embed_code_when_one_backend_"><code>ev_embed</code> - when one backend isn't enough...</a></li> 65<li><a href="#code_ev_embed_code_when_one_backend_"><code>ev_embed</code> - when one backend isn't enough...</a>
66<ul><li><a href="#Watcher_Specific_Functions_and_Data_-9">Watcher-Specific Functions and Data Members</a></li>
67</ul>
68</li>
40<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> 69<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>
70<ul><li><a href="#Watcher_Specific_Functions_and_Data_-10">Watcher-Specific Functions and Data Members</a></li>
71</ul>
72</li>
41</ul> 73</ul>
42</li> 74</li>
43<li><a href="#OTHER_FUNCTIONS">OTHER FUNCTIONS</a></li> 75<li><a href="#OTHER_FUNCTIONS">OTHER FUNCTIONS</a></li>
44<li><a href="#LIBEVENT_EMULATION">LIBEVENT EMULATION</a></li> 76<li><a href="#LIBEVENT_EMULATION">LIBEVENT EMULATION</a></li>
45<li><a href="#C_SUPPORT">C++ SUPPORT</a></li> 77<li><a href="#C_SUPPORT">C++ SUPPORT</a></li>
… …
59<li><a href="#AUTHOR">AUTHOR</a> 91<li><a href="#AUTHOR">AUTHOR</a>
60</li> 92</li>
61</ul><hr /> 93</ul><hr />
62<!-- INDEX END --> 94<!-- INDEX END -->
63 95
64<h1 id="NAME">NAME</h1><p><a href="#TOP" class="toplink">Top</a></p> 96<h1 id="NAME">NAME</h1>
65<div id="NAME_CONTENT"> 97<div id="NAME_CONTENT">
66<p>libev - a high performance full-featured event loop written in C</p> 98<p>libev - a high performance full-featured event loop written in C</p>
67 99
68</div> 100</div>
69<h1 id="SYNOPSIS">SYNOPSIS</h1><p><a href="#TOP" class="toplink">Top</a></p> 101<h1 id="SYNOPSIS">SYNOPSIS</h1>
70<div id="SYNOPSIS_CONTENT"> 102<div id="SYNOPSIS_CONTENT">
71<pre> #include &lt;ev.h&gt; 103<pre> #include &lt;ev.h&gt;
72 104
73</pre> 105</pre>
74 106
75</div> 107</div>
76<h1 id="DESCRIPTION">DESCRIPTION</h1><p><a href="#TOP" class="toplink">Top</a></p> 108<h1 id="EXAMPLE_PROGRAM">EXAMPLE PROGRAM</h1>
109<div id="EXAMPLE_PROGRAM_CONTENT">
110<pre> #include &lt;ev.h&gt;
111
112 ev_io stdin_watcher;
113 ev_timer timeout_watcher;
114
115 /* called when data readable on stdin */
116 static void
117 stdin_cb (EV_P_ struct ev_io *w, int revents)
118 {
119 /* puts (&quot;stdin ready&quot;); */
120 ev_io_stop (EV_A_ w); /* just a syntax example */
121 ev_unloop (EV_A_ EVUNLOOP_ALL); /* leave all loop calls */
122 }
123
124 static void
125 timeout_cb (EV_P_ struct ev_timer *w, int revents)
126 {
127 /* puts (&quot;timeout&quot;); */
128 ev_unloop (EV_A_ EVUNLOOP_ONE); /* leave one loop call */
129 }
130
131 int
132 main (void)
133 {
134 struct ev_loop *loop = ev_default_loop (0);
135
136 /* initialise an io watcher, then start it */
137 ev_io_init (&amp;stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ);
138 ev_io_start (loop, &amp;stdin_watcher);
139
140 /* simple non-repeating 5.5 second timeout */
141 ev_timer_init (&amp;timeout_watcher, timeout_cb, 5.5, 0.);
142 ev_timer_start (loop, &amp;timeout_watcher);
143
144 /* loop till timeout or data ready */
145 ev_loop (loop, 0);
146
147 return 0;
148 }
149
150</pre>
151
152</div>
153<h1 id="DESCRIPTION">DESCRIPTION</h1>
77<div id="DESCRIPTION_CONTENT"> 154<div id="DESCRIPTION_CONTENT">
155<p>The newest version of this document is also available as a html-formatted
156web page you might find easier to navigate when reading it for the first
157time: <a href="http://cvs.schmorp.de/libev/ev.html">http://cvs.schmorp.de/libev/ev.html</a>.</p>
78<p>Libev is an event loop: you register interest in certain events (such as a 158<p>Libev is an event loop: you register interest in certain events (such as a
79file descriptor being readable or a timeout occuring), and it will manage 159file descriptor being readable or a timeout occuring), and it will manage
80these event sources and provide your program with events.</p> 160these event sources and provide your program with events.</p>
81<p>To do this, it must take more or less complete control over your process 161<p>To do this, it must take more or less complete control over your process
82(or thread) by executing the <i>event loop</i> handler, and will then 162(or thread) by executing the <i>event loop</i> handler, and will then
… …
85watchers</i>, which are relatively small C structures you initialise with the 165watchers</i>, which are relatively small C structures you initialise with the
86details of the event, and then hand it over to libev by <i>starting</i> the 166details of the event, and then hand it over to libev by <i>starting</i> the
87watcher.</p> 167watcher.</p>
88 168
89</div> 169</div>
90<h1 id="FEATURES">FEATURES</h1><p><a href="#TOP" class="toplink">Top</a></p> 170<h1 id="FEATURES">FEATURES</h1>
91<div id="FEATURES_CONTENT"> 171<div id="FEATURES_CONTENT">
92<p>Libev supports select, poll, the linux-specific epoll and the bsd-specific 172<p>Libev supports <code>select</code>, <code>poll</code>, the Linux-specific <code>epoll</code>, the
93kqueue mechanisms for file descriptor events, relative timers, absolute 173BSD-specific <code>kqueue</code> and the Solaris-specific event port mechanisms
94timers with customised rescheduling, signal events, process status change 174for file descriptor events (<code>ev_io</code>), the Linux <code>inotify</code> interface
95events (related to SIGCHLD), and event watchers dealing with the event 175(for <code>ev_stat</code>), relative timers (<code>ev_timer</code>), absolute timers
96loop mechanism itself (idle, prepare and check watchers). It also is quite 176with customised rescheduling (<code>ev_periodic</code>), synchronous signals
177(<code>ev_signal</code>), process status change events (<code>ev_child</code>), and event
178watchers dealing with the event loop mechanism itself (<code>ev_idle</code>,
179<code>ev_embed</code>, <code>ev_prepare</code> and <code>ev_check</code> watchers) as well as
180file watchers (<code>ev_stat</code>) and even limited support for fork events
181(<code>ev_fork</code>).</p>
182<p>It also is quite fast (see this
97fast (see this <a href="http://libev.schmorp.de/bench.html">benchmark</a> comparing 183<a href="http://libev.schmorp.de/bench.html">benchmark</a> comparing it to libevent
98it to libevent for example).</p> 184for example).</p>
99 185
100</div> 186</div>
101<h1 id="CONVENTIONS">CONVENTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p> 187<h1 id="CONVENTIONS">CONVENTIONS</h1>
102<div id="CONVENTIONS_CONTENT"> 188<div id="CONVENTIONS_CONTENT">
103<p>Libev is very configurable. In this manual the default configuration 189<p>Libev is very configurable. In this manual the default configuration will
104will be described, which supports multiple event loops. For more info 190be described, which supports multiple event loops. For more info about
105about various configuration options please have a look at the file 191various configuration options please have a look at <strong>EMBED</strong> section in
106<cite>README.embed</cite> in the libev distribution. If libev was configured without 192this manual. If libev was configured without support for multiple event
107support for multiple event loops, then all functions taking an initial 193loops, then all functions taking an initial argument of name <code>loop</code>
108argument of name <code>loop</code> (which is always of type <code>struct ev_loop *</code>) 194(which is always of type <code>struct ev_loop *</code>) will not have this argument.</p>
109will not have this argument.</p>
110 195
111</div> 196</div>
112<h1 id="TIME_REPRESENTATION">TIME REPRESENTATION</h1><p><a href="#TOP" class="toplink">Top</a></p> 197<h1 id="TIME_REPRESENTATION">TIME REPRESENTATION</h1>
113<div id="TIME_REPRESENTATION_CONTENT"> 198<div id="TIME_REPRESENTATION_CONTENT">
114<p>Libev represents time as a single floating point number, representing the 199<p>Libev represents time as a single floating point number, representing the
115(fractional) number of seconds since the (POSIX) epoch (somewhere near 200(fractional) number of seconds since the (POSIX) epoch (somewhere near
116the beginning of 1970, details are complicated, don't ask). This type is 201the beginning of 1970, details are complicated, don't ask). This type is
117called <code>ev_tstamp</code>, which is what you should use too. It usually aliases 202called <code>ev_tstamp</code>, which is what you should use too. It usually aliases
118to the <code>double</code> type in C, and when you need to do any calculations on 203to the <code>double</code> type in C, and when you need to do any calculations on
119it, you should treat it as such.</p> 204it, you should treat it as such.</p>
120 205
121</div> 206</div>
122<h1 id="GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p> 207<h1 id="GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</h1>
123<div id="GLOBAL_FUNCTIONS_CONTENT"> 208<div id="GLOBAL_FUNCTIONS_CONTENT">
124<p>These functions can be called anytime, even before initialising the 209<p>These functions can be called anytime, even before initialising the
125library in any way.</p> 210library in any way.</p>
126<dl> 211<dl>
127 <dt>ev_tstamp ev_time ()</dt> 212 <dt>ev_tstamp ev_time ()</dt>
… …
131you actually want to know.</p> 216you actually want to know.</p>
132 </dd> 217 </dd>
133 <dt>int ev_version_major ()</dt> 218 <dt>int ev_version_major ()</dt>
134 <dt>int ev_version_minor ()</dt> 219 <dt>int ev_version_minor ()</dt>
135 <dd> 220 <dd>
136 <p>You can find out the major and minor version numbers of the library 221 <p>You can find out the major and minor ABI version numbers of the library
137you linked against by calling the functions <code>ev_version_major</code> and 222you linked against by calling the functions <code>ev_version_major</code> and
138<code>ev_version_minor</code>. If you want, you can compare against the global 223<code>ev_version_minor</code>. If you want, you can compare against the global
139symbols <code>EV_VERSION_MAJOR</code> and <code>EV_VERSION_MINOR</code>, which specify the 224symbols <code>EV_VERSION_MAJOR</code> and <code>EV_VERSION_MINOR</code>, which specify the
140version of the library your program was compiled against.</p> 225version of the library your program was compiled against.</p>
226 <p>These version numbers refer to the ABI version of the library, not the
227release version.</p>
141 <p>Usually, it's a good idea to terminate if the major versions mismatch, 228 <p>Usually, it's a good idea to terminate if the major versions mismatch,
142as this indicates an incompatible change. Minor versions are usually 229as this indicates an incompatible change. Minor versions are usually
143compatible to older versions, so a larger minor version alone is usually 230compatible to older versions, so a larger minor version alone is usually
144not a problem.</p> 231not a problem.</p>
145 <p>Example: make sure we haven't accidentally been linked against the wrong 232 <p>Example: Make sure we haven't accidentally been linked against the wrong
146version:</p> 233version.</p>
147<pre> assert ((&quot;libev version mismatch&quot;, 234<pre> assert ((&quot;libev version mismatch&quot;,
148 ev_version_major () == EV_VERSION_MAJOR 235 ev_version_major () == EV_VERSION_MAJOR
149 &amp;&amp; ev_version_minor () &gt;= EV_VERSION_MINOR)); 236 &amp;&amp; ev_version_minor () &gt;= EV_VERSION_MINOR));
150 237
151</pre> 238</pre>
… …
181recommended ones.</p> 268recommended ones.</p>
182 <p>See the description of <code>ev_embed</code> watchers for more info.</p> 269 <p>See the description of <code>ev_embed</code> watchers for more info.</p>
183 </dd> 270 </dd>
184 <dt>ev_set_allocator (void *(*cb)(void *ptr, long size))</dt> 271 <dt>ev_set_allocator (void *(*cb)(void *ptr, long size))</dt>
185 <dd> 272 <dd>
186 <p>Sets the allocation function to use (the prototype is similar to the 273 <p>Sets the allocation function to use (the prototype is similar - the
187realloc C function, the semantics are identical). It is used to allocate 274semantics is identical - to the realloc C function). It is used to
188and free memory (no surprises here). If it returns zero when memory 275allocate and free memory (no surprises here). If it returns zero when
189needs to be allocated, the library might abort or take some potentially 276memory needs to be allocated, the library might abort or take some
190destructive action. The default is your system realloc function.</p> 277potentially destructive action. The default is your system realloc
278function.</p>
191 <p>You could override this function in high-availability programs to, say, 279 <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, 280free 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> 281or 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 282 <p>Example: Replace the libev allocator with one that waits a bit and then
195retries: better than mine).</p> 283retries).</p>
196<pre> static void * 284<pre> static void *
197 persistent_realloc (void *ptr, long size) 285 persistent_realloc (void *ptr, size_t size)
198 { 286 {
199 for (;;) 287 for (;;)
200 { 288 {
201 void *newptr = realloc (ptr, size); 289 void *newptr = realloc (ptr, size);
202 290
… …
219indicating the system call or subsystem causing the problem. If this 307indicating the system call or subsystem causing the problem. If this
220callback is set, then libev will expect it to remedy the sitution, no 308callback is set, then libev will expect it to remedy the sitution, no
221matter what, when it returns. That is, libev will generally retry the 309matter what, when it returns. That is, libev will generally retry the
222requested operation, or, if the condition doesn't go away, do bad stuff 310requested operation, or, if the condition doesn't go away, do bad stuff
223(such as abort).</p> 311(such as abort).</p>
224 <p>Example: do the same thing as libev does internally:</p> 312 <p>Example: This is basically the same thing that libev does internally, too.</p>
225<pre> static void 313<pre> static void
226 fatal_error (const char *msg) 314 fatal_error (const char *msg)
227 { 315 {
228 perror (msg); 316 perror (msg);
229 abort (); 317 abort ();
… …
235</pre> 323</pre>
236 </dd> 324 </dd>
237</dl> 325</dl>
238 326
239</div> 327</div>
240<h1 id="FUNCTIONS_CONTROLLING_THE_EVENT_LOOP">FUNCTIONS CONTROLLING THE EVENT LOOP</h1><p><a href="#TOP" class="toplink">Top</a></p> 328<h1 id="FUNCTIONS_CONTROLLING_THE_EVENT_LOOP">FUNCTIONS CONTROLLING THE EVENT LOOP</h1>
241<div id="FUNCTIONS_CONTROLLING_THE_EVENT_LOOP-2"> 329<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 330<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 331types of such loops, the <i>default</i> loop, which supports signals and child
244events, and dynamically created loops which do not.</p> 332events, and dynamically created loops which do not.</p>
245<p>If you use threads, a common model is to run the default event loop 333<p>If you use threads, a common model is to run the default event loop
… …
274<code>LIBEV_FLAGS</code>. Otherwise (the default), this environment variable will 362<code>LIBEV_FLAGS</code>. Otherwise (the default), this environment variable will
275override the flags completely if it is found in the environment. This is 363override 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 364useful to try out specific backends to test their performance, or to work
277around bugs.</p> 365around bugs.</p>
278 </dd> 366 </dd>
367 <dt><code>EVFLAG_FORKCHECK</code></dt>
368 <dd>
369 <p>Instead of calling <code>ev_default_fork</code> or <code>ev_loop_fork</code> manually after
370a fork, you can also make libev check for a fork in each iteration by
371enabling this flag.</p>
372 <p>This works by calling <code>getpid ()</code> on every iteration of the loop,
373and thus this might slow down your event loop if you do a lot of loop
374iterations and little real work, but is usually not noticeable (on my
375Linux system for example, <code>getpid</code> is actually a simple 5-insn sequence
376without a syscall and thus <i>very</i> fast, but my Linux system also has
377<code>pthread_atfork</code> which is even faster).</p>
378 <p>The big advantage of this flag is that you can forget about fork (and
379forget about forgetting to tell libev about forking) when you use this
380flag.</p>
381 <p>This flag setting cannot be overriden or specified in the <code>LIBEV_FLAGS</code>
382environment variable.</p>
383 </dd>
279 <dt><code>EVBACKEND_SELECT</code> (value 1, portable select backend)</dt> 384 <dt><code>EVBACKEND_SELECT</code> (value 1, portable select backend)</dt>
280 <dd> 385 <dd>
281 <p>This is your standard select(2) backend. Not <i>completely</i> standard, as 386 <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, 387libev tries to roll its own fd_set with no limits on the number of fds,
283but if that fails, expect a fairly low limit on the number of fds when 388but if that fails, expect a fairly low limit on the number of fds when
… …
365 <dd> 470 <dd>
366 <p>Similar to <code>ev_default_loop</code>, but always creates a new event loop that is 471 <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 472always 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 473handle signal and child watchers, and attempts to do so will be greeted by
369undefined behaviour (or a failed assertion if assertions are enabled).</p> 474undefined 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> 475 <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); 476<pre> struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);
372 if (!epoller) 477 if (!epoller)
373 fatal (&quot;no epoll found here, maybe it hides under your chair&quot;); 478 fatal (&quot;no epoll found here, maybe it hides under your chair&quot;);
374 479
375</pre> 480</pre>
… …
411 <dt>ev_loop_fork (loop)</dt> 516 <dt>ev_loop_fork (loop)</dt>
412 <dd> 517 <dd>
413 <p>Like <code>ev_default_fork</code>, but acts on an event loop created by 518 <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 519<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> 520after fork, and how you do this is entirely your own problem.</p>
521 </dd>
522 <dt>unsigned int ev_loop_count (loop)</dt>
523 <dd>
524 <p>Returns the count of loop iterations for the loop, which is identical to
525the number of times libev did poll for new events. It starts at <code>0</code> and
526happily wraps around with enough iterations.</p>
527 <p>This value can sometimes be useful as a generation counter of sorts (it
528&quot;ticks&quot; the number of loop iterations), as it roughly corresponds with
529<code>ev_prepare</code> and <code>ev_check</code> calls.</p>
416 </dd> 530 </dd>
417 <dt>unsigned int ev_backend (loop)</dt> 531 <dt>unsigned int ev_backend (loop)</dt>
418 <dd> 532 <dd>
419 <p>Returns one of the <code>EVBACKEND_*</code> flags indicating the event backend in 533 <p>Returns one of the <code>EVBACKEND_*</code> flags indicating the event backend in
420use.</p> 534use.</p>
… …
448one iteration of the loop. This is useful if you are waiting for some 562one iteration of the loop. This is useful if you are waiting for some
449external event in conjunction with something not expressible using other 563external event in conjunction with something not expressible using other
450libev watchers. However, a pair of <code>ev_prepare</code>/<code>ev_check</code> watchers is 564libev watchers. However, a pair of <code>ev_prepare</code>/<code>ev_check</code> watchers is
451usually a better approach for this kind of thing.</p> 565usually a better approach for this kind of thing.</p>
452 <p>Here are the gory details of what <code>ev_loop</code> does:</p> 566 <p>Here are the gory details of what <code>ev_loop</code> does:</p>
567<pre> - Before the first iteration, call any pending watchers.
453<pre> * If there are no active watchers (reference count is zero), return. 568 * If there are no active watchers (reference count is zero), return.
454 - Queue prepare watchers and then call all outstanding watchers. 569 - Queue all prepare watchers and then call all outstanding watchers.
455 - If we have been forked, recreate the kernel state. 570 - If we have been forked, recreate the kernel state.
456 - Update the kernel state with all outstanding changes. 571 - Update the kernel state with all outstanding changes.
457 - Update the &quot;event loop time&quot;. 572 - Update the &quot;event loop time&quot;.
458 - Calculate for how long to block. 573 - Calculate for how long to block.
459 - Block the process, waiting for any events. 574 - Block the process, waiting for any events.
… …
468 be handled here by queueing them when their watcher gets executed. 583 be handled here by queueing them when their watcher gets executed.
469 - If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK 584 - If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK
470 were used, return, otherwise continue with step *. 585 were used, return, otherwise continue with step *.
471 586
472</pre> 587</pre>
473 <p>Example: queue some jobs and then loop until no events are outsanding 588 <p>Example: Queue some jobs and then loop until no events are outsanding
474anymore.</p> 589anymore.</p>
475<pre> ... queue jobs here, make sure they register event watchers as long 590<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..) 591 ... as they still have work to do (even an idle watcher will do..)
477 ev_loop (my_loop, 0); 592 ev_loop (my_loop, 0);
478 ... jobs done. yeah! 593 ... jobs done. yeah!
… …
497example, libev itself uses this for its internal signal pipe: It is not 612example, 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 613visible 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 614no 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 615way 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> 616libraries. 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> 617 <p>Example: Create a signal watcher, but keep it from keeping <code>ev_loop</code>
503running when nothing else is active.</p> 618running when nothing else is active.</p>
504<pre> struct dv_signal exitsig; 619<pre> struct ev_signal exitsig;
505 ev_signal_init (&amp;exitsig, sig_cb, SIGINT); 620 ev_signal_init (&amp;exitsig, sig_cb, SIGINT);
506 ev_signal_start (myloop, &amp;exitsig); 621 ev_signal_start (loop, &amp;exitsig);
507 evf_unref (myloop); 622 evf_unref (loop);
508 623
509</pre> 624</pre>
510 <p>Example: for some weird reason, unregister the above signal handler again.</p> 625 <p>Example: For some weird reason, unregister the above signal handler again.</p>
511<pre> ev_ref (myloop); 626<pre> ev_ref (loop);
512 ev_signal_stop (myloop, &amp;exitsig); 627 ev_signal_stop (loop, &amp;exitsig);
513 628
514</pre> 629</pre>
515 </dd> 630 </dd>
516</dl> 631</dl>
517 632
518 633
519 634
520 635
521 636
522</div> 637</div>
523<h1 id="ANATOMY_OF_A_WATCHER">ANATOMY OF A WATCHER</h1><p><a href="#TOP" class="toplink">Top</a></p> 638<h1 id="ANATOMY_OF_A_WATCHER">ANATOMY OF A WATCHER</h1>
524<div id="ANATOMY_OF_A_WATCHER_CONTENT"> 639<div id="ANATOMY_OF_A_WATCHER_CONTENT">
525<p>A watcher is a structure that you create and register to record your 640<p>A watcher is a structure that you create and register to record your
526interest in some event. For instance, if you want to wait for STDIN to 641interest in some event. For instance, if you want to wait for STDIN to
527become readable, you would create an <code>ev_io</code> watcher for that:</p> 642become readable, you would create an <code>ev_io</code> watcher for that:</p>
528<pre> static void my_cb (struct ev_loop *loop, struct ev_io *w, int revents) 643<pre> static void my_cb (struct ev_loop *loop, struct ev_io *w, int revents)
… …
688 <dt>bool ev_is_pending (ev_TYPE *watcher)</dt> 803 <dt>bool ev_is_pending (ev_TYPE *watcher)</dt>
689 <dd> 804 <dd>
690 <p>Returns a true value iff the watcher is pending, (i.e. it has outstanding 805 <p>Returns a true value iff the watcher is pending, (i.e. it has outstanding
691events but its callback has not yet been invoked). As long as a watcher 806events but its callback has not yet been invoked). As long as a watcher
692is pending (but not active) you must not call an init function on it (but 807is pending (but not active) you must not call an init function on it (but
693<code>ev_TYPE_set</code> is safe) and you must make sure the watcher is available to 808<code>ev_TYPE_set</code> is safe), you must not change its priority, and you must
694libev (e.g. you cnanot <code>free ()</code> it).</p> 809make sure the watcher is available to libev (e.g. you cannot <code>free ()</code>
810it).</p>
695 </dd> 811 </dd>
696 <dt>callback = ev_cb (ev_TYPE *watcher)</dt> 812 <dt>callback ev_cb (ev_TYPE *watcher)</dt>
697 <dd> 813 <dd>
698 <p>Returns the callback currently set on the watcher.</p> 814 <p>Returns the callback currently set on the watcher.</p>
699 </dd> 815 </dd>
700 <dt>ev_cb_set (ev_TYPE *watcher, callback)</dt> 816 <dt>ev_cb_set (ev_TYPE *watcher, callback)</dt>
701 <dd> 817 <dd>
702 <p>Change the callback. You can change the callback at virtually any time 818 <p>Change the callback. You can change the callback at virtually any time
703(modulo threads).</p> 819(modulo threads).</p>
820 </dd>
821 <dt>ev_set_priority (ev_TYPE *watcher, priority)</dt>
822 <dt>int ev_priority (ev_TYPE *watcher)</dt>
823 <dd>
824 <p>Set and query the priority of the watcher. The priority is a small
825integer between <code>EV_MAXPRI</code> (default: <code>2</code>) and <code>EV_MINPRI</code>
826(default: <code>-2</code>). Pending watchers with higher priority will be invoked
827before watchers with lower priority, but priority will not keep watchers
828from being executed (except for <code>ev_idle</code> watchers).</p>
829 <p>This means that priorities are <i>only</i> used for ordering callback
830invocation after new events have been received. This is useful, for
831example, to reduce latency after idling, or more often, to bind two
832watchers on the same event and make sure one is called first.</p>
833 <p>If you need to suppress invocation when higher priority events are pending
834you need to look at <code>ev_idle</code> watchers, which provide this functionality.</p>
835 <p>You <i>must not</i> change the priority of a watcher as long as it is active or
836pending.</p>
837 <p>The default priority used by watchers when no priority has been set is
838always <code>0</code>, which is supposed to not be too high and not be too low :).</p>
839 <p>Setting a priority outside the range of <code>EV_MINPRI</code> to <code>EV_MAXPRI</code> is
840fine, as long as you do not mind that the priority value you query might
841or might not have been adjusted to be within valid range.</p>
842 </dd>
843 <dt>ev_invoke (loop, ev_TYPE *watcher, int revents)</dt>
844 <dd>
845 <p>Invoke the <code>watcher</code> with the given <code>loop</code> and <code>revents</code>. Neither
846<code>loop</code> nor <code>revents</code> need to be valid as long as the watcher callback
847can deal with that fact.</p>
848 </dd>
849 <dt>int ev_clear_pending (loop, ev_TYPE *watcher)</dt>
850 <dd>
851 <p>If the watcher is pending, this function returns clears its pending status
852and returns its <code>revents</code> bitset (as if its callback was invoked). If the
853watcher isn't pending it does nothing and returns <code>0</code>.</p>
704 </dd> 854 </dd>
705</dl> 855</dl>
706 856
707 857
708 858
… …
733 struct my_io *w = (struct my_io *)w_; 883 struct my_io *w = (struct my_io *)w_;
734 ... 884 ...
735 } 885 }
736 886
737</pre> 887</pre>
738<p>More interesting and less C-conformant ways of catsing your callback type 888<p>More interesting and less C-conformant ways of casting your callback type
739have been omitted....</p> 889instead have been omitted.</p>
890<p>Another common scenario is having some data structure with multiple
891watchers:</p>
892<pre> struct my_biggy
893 {
894 int some_data;
895 ev_timer t1;
896 ev_timer t2;
897 }
740 898
899</pre>
900<p>In this case getting the pointer to <code>my_biggy</code> is a bit more complicated,
901you need to use <code>offsetof</code>:</p>
902<pre> #include &lt;stddef.h&gt;
741 903
904 static void
905 t1_cb (EV_P_ struct ev_timer *w, int revents)
906 {
907 struct my_biggy big = (struct my_biggy *
908 (((char *)w) - offsetof (struct my_biggy, t1));
909 }
742 910
911 static void
912 t2_cb (EV_P_ struct ev_timer *w, int revents)
913 {
914 struct my_biggy big = (struct my_biggy *
915 (((char *)w) - offsetof (struct my_biggy, t2));
916 }
743 917
744 918
919
920
921</pre>
922
745</div> 923</div>
746<h1 id="WATCHER_TYPES">WATCHER TYPES</h1><p><a href="#TOP" class="toplink">Top</a></p> 924<h1 id="WATCHER_TYPES">WATCHER TYPES</h1>
747<div id="WATCHER_TYPES_CONTENT"> 925<div id="WATCHER_TYPES_CONTENT">
748<p>This section describes each watcher in detail, but will not repeat 926<p>This section describes each watcher in detail, but will not repeat
749information given in the last section. Any initialisation/set macros, 927information given in the last section. Any initialisation/set macros,
750functions and members specific to the watcher type are explained.</p> 928functions and members specific to the watcher type are explained.</p>
751<p>Members are additionally marked with either <i>[read-only]</i>, meaning that, 929<p>Members are additionally marked with either <i>[read-only]</i>, meaning that,
… …
791this situation even with a relatively standard program structure. Thus 969this situation even with a relatively standard program structure. Thus
792it is best to always use non-blocking I/O: An extra <code>read</code>(2) returning 970it is best to always use non-blocking I/O: An extra <code>read</code>(2) returning
793<code>EAGAIN</code> is far preferable to a program hanging until some data arrives.</p> 971<code>EAGAIN</code> is far preferable to a program hanging until some data arrives.</p>
794<p>If you cannot run the fd in non-blocking mode (for example you should not 972<p>If you cannot run the fd in non-blocking mode (for example you should not
795play around with an Xlib connection), then you have to seperately re-test 973play around with an Xlib connection), then you have to seperately re-test
796wether a file descriptor is really ready with a known-to-be good interface 974whether a file descriptor is really ready with a known-to-be good interface
797such as poll (fortunately in our Xlib example, Xlib already does this on 975such as poll (fortunately in our Xlib example, Xlib already does this on
798its own, so its quite safe to use).</p> 976its own, so its quite safe to use).</p>
977
978</div>
979<h3 id="The_special_problem_of_disappearing_">The special problem of disappearing file descriptors</h3>
980<div id="The_special_problem_of_disappearing_-2">
981<p>Some backends (e.g kqueue, epoll) need to be told about closing a file
982descriptor (either by calling <code>close</code> explicitly or by any other means,
983such as <code>dup</code>). The reason is that you register interest in some file
984descriptor, but when it goes away, the operating system will silently drop
985this interest. If another file descriptor with the same number then is
986registered with libev, there is no efficient way to see that this is, in
987fact, a different file descriptor.</p>
988<p>To avoid having to explicitly tell libev about such cases, libev follows
989the following policy: Each time <code>ev_io_set</code> is being called, libev
990will assume that this is potentially a new file descriptor, otherwise
991it is assumed that the file descriptor stays the same. That means that
992you <i>have</i> to call <code>ev_io_set</code> (or <code>ev_io_init</code>) when you change the
993descriptor even if the file descriptor number itself did not change.</p>
994<p>This is how one would do it normally anyway, the important point is that
995the libev application should not optimise around libev but should leave
996optimisations to libev.</p>
997
998
999
1000
1001
1002</div>
1003<h3 id="Watcher_Specific_Functions">Watcher-Specific Functions</h3>
1004<div id="Watcher_Specific_Functions_CONTENT">
799<dl> 1005<dl>
800 <dt>ev_io_init (ev_io *, callback, int fd, int events)</dt> 1006 <dt>ev_io_init (ev_io *, callback, int fd, int events)</dt>
801 <dt>ev_io_set (ev_io *, int fd, int events)</dt> 1007 <dt>ev_io_set (ev_io *, int fd, int events)</dt>
802 <dd> 1008 <dd>
803 <p>Configures an <code>ev_io</code> watcher. The <code>fd</code> is the file descriptor to 1009 <p>Configures an <code>ev_io</code> watcher. The <code>fd</code> is the file descriptor to
… …
811 <dt>int events [read-only]</dt> 1017 <dt>int events [read-only]</dt>
812 <dd> 1018 <dd>
813 <p>The events being watched.</p> 1019 <p>The events being watched.</p>
814 </dd> 1020 </dd>
815</dl> 1021</dl>
816<p>Example: call <code>stdin_readable_cb</code> when STDIN_FILENO has become, well 1022<p>Example: Call <code>stdin_readable_cb</code> when STDIN_FILENO has become, well
817readable, but only once. Since it is likely line-buffered, you could 1023readable, but only once. Since it is likely line-buffered, you could
818attempt to read a whole line in the callback:</p> 1024attempt to read a whole line in the callback.</p>
819<pre> static void 1025<pre> static void
820 stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents) 1026 stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents)
821 { 1027 {
822 ev_io_stop (loop, w); 1028 ev_io_stop (loop, w);
823 .. read from stdin here (or from w-&gt;fd) and haqndle any I/O errors 1029 .. read from stdin here (or from w-&gt;fd) and haqndle any I/O errors
… …
854 1060
855</pre> 1061</pre>
856<p>The callback is guarenteed to be invoked only when its timeout has passed, 1062<p>The callback is guarenteed to be invoked only when its timeout has passed,
857but if multiple timers become ready during the same loop iteration then 1063but if multiple timers become ready during the same loop iteration then
858order of execution is undefined.</p> 1064order of execution is undefined.</p>
1065
1066</div>
1067<h3 id="Watcher_Specific_Functions_and_Data_">Watcher-Specific Functions and Data Members</h3>
1068<div id="Watcher_Specific_Functions_and_Data_-2">
859<dl> 1069<dl>
860 <dt>ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)</dt> 1070 <dt>ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)</dt>
861 <dt>ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)</dt> 1071 <dt>ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)</dt>
862 <dd> 1072 <dd>
863 <p>Configure the timer to trigger after <code>after</code> seconds. If <code>repeat</code> is 1073 <p>Configure the timer to trigger after <code>after</code> seconds. If <code>repeat</code> is
… …
872 </dd> 1082 </dd>
873 <dt>ev_timer_again (loop)</dt> 1083 <dt>ev_timer_again (loop)</dt>
874 <dd> 1084 <dd>
875 <p>This will act as if the timer timed out and restart it again if it is 1085 <p>This will act as if the timer timed out and restart it again if it is
876repeating. The exact semantics are:</p> 1086repeating. The exact semantics are:</p>
1087 <p>If the timer is pending, its pending status is cleared.</p>
877 <p>If the timer is started but nonrepeating, stop it.</p> 1088 <p>If the timer is started but nonrepeating, stop it (as if it timed out).</p>
878 <p>If the timer is repeating, either start it if necessary (with the repeat 1089 <p>If the timer is repeating, either start it if necessary (with the
879value), or reset the running timer to the repeat value.</p> 1090<code>repeat</code> value), or reset the running timer to the <code>repeat</code> value.</p>
880 <p>This sounds a bit complicated, but here is a useful and typical 1091 <p>This sounds a bit complicated, but here is a useful and typical
881example: Imagine you have a tcp connection and you want a so-called 1092example: Imagine you have a tcp connection and you want a so-called idle
882idle timeout, that is, you want to be called when there have been, 1093timeout, that is, you want to be called when there have been, say, 60
883say, 60 seconds of inactivity on the socket. The easiest way to do 1094seconds of inactivity on the socket. The easiest way to do this is to
884this is to configure an <code>ev_timer</code> with <code>after</code>=<code>repeat</code>=<code>60</code> and calling 1095configure an <code>ev_timer</code> with a <code>repeat</code> value of <code>60</code> and then call
885<code>ev_timer_again</code> each time you successfully read or write some data. If 1096<code>ev_timer_again</code> each time you successfully read or write some data. If
886you go into an idle state where you do not expect data to travel on the 1097you go into an idle state where you do not expect data to travel on the
887socket, you can stop the timer, and again will automatically restart it if 1098socket, you can <code>ev_timer_stop</code> the timer, and <code>ev_timer_again</code> will
888need be.</p> 1099automatically restart it if need be.</p>
889 <p>You can also ignore the <code>after</code> value and <code>ev_timer_start</code> altogether 1100 <p>That means you can ignore the <code>after</code> value and <code>ev_timer_start</code>
890and only ever use the <code>repeat</code> value:</p> 1101altogether and only ever use the <code>repeat</code> value and <code>ev_timer_again</code>:</p>
891<pre> ev_timer_init (timer, callback, 0., 5.); 1102<pre> ev_timer_init (timer, callback, 0., 5.);
892 ev_timer_again (loop, timer); 1103 ev_timer_again (loop, timer);
893 ... 1104 ...
894 timer-&gt;again = 17.; 1105 timer-&gt;again = 17.;
895 ev_timer_again (loop, timer); 1106 ev_timer_again (loop, timer);
896 ... 1107 ...
897 timer-&gt;again = 10.; 1108 timer-&gt;again = 10.;
898 ev_timer_again (loop, timer); 1109 ev_timer_again (loop, timer);
899 1110
900</pre> 1111</pre>
901 <p>This is more efficient then stopping/starting the timer eahc time you want 1112 <p>This is more slightly efficient then stopping/starting the timer each time
902to modify its timeout value.</p> 1113you want to modify its timeout value.</p>
903 </dd> 1114 </dd>
904 <dt>ev_tstamp repeat [read-write]</dt> 1115 <dt>ev_tstamp repeat [read-write]</dt>
905 <dd> 1116 <dd>
906 <p>The current <code>repeat</code> value. Will be used each time the watcher times out 1117 <p>The current <code>repeat</code> value. Will be used each time the watcher times out
907or <code>ev_timer_again</code> is called and determines the next timeout (if any), 1118or <code>ev_timer_again</code> is called and determines the next timeout (if any),
908which is also when any modifications are taken into account.</p> 1119which is also when any modifications are taken into account.</p>
909 </dd> 1120 </dd>
910</dl> 1121</dl>
911<p>Example: create a timer that fires after 60 seconds.</p> 1122<p>Example: Create a timer that fires after 60 seconds.</p>
912<pre> static void 1123<pre> static void
913 one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) 1124 one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents)
914 { 1125 {
915 .. one minute over, w is actually stopped right here 1126 .. one minute over, w is actually stopped right here
916 } 1127 }
… …
918 struct ev_timer mytimer; 1129 struct ev_timer mytimer;
919 ev_timer_init (&amp;mytimer, one_minute_cb, 60., 0.); 1130 ev_timer_init (&amp;mytimer, one_minute_cb, 60., 0.);
920 ev_timer_start (loop, &amp;mytimer); 1131 ev_timer_start (loop, &amp;mytimer);
921 1132
922</pre> 1133</pre>
923<p>Example: create a timeout timer that times out after 10 seconds of 1134<p>Example: Create a timeout timer that times out after 10 seconds of
924inactivity.</p> 1135inactivity.</p>
925<pre> static void 1136<pre> static void
926 timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents) 1137 timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents)
927 { 1138 {
928 .. ten seconds without any activity 1139 .. ten seconds without any activity
… …
951but on wallclock time (absolute time). You can tell a periodic watcher 1162but on wallclock time (absolute time). You can tell a periodic watcher
952to trigger &quot;at&quot; some specific point in time. For example, if you tell a 1163to trigger &quot;at&quot; some specific point in time. For example, if you tell a
953periodic watcher to trigger in 10 seconds (by specifiying e.g. <code>ev_now () 1164periodic watcher to trigger in 10 seconds (by specifiying e.g. <code>ev_now ()
954+ 10.</code>) and then reset your system clock to the last year, then it will 1165+ 10.</code>) and then reset your system clock to the last year, then it will
955take a year to trigger the event (unlike an <code>ev_timer</code>, which would trigger 1166take a year to trigger the event (unlike an <code>ev_timer</code>, which would trigger
956roughly 10 seconds later and of course not if you reset your system time 1167roughly 10 seconds later).</p>
957again).</p>
958<p>They can also be used to implement vastly more complex timers, such as 1168<p>They can also be used to implement vastly more complex timers, such as
959triggering an event on eahc midnight, local time.</p> 1169triggering an event on each midnight, local time or other, complicated,
1170rules.</p>
960<p>As with timers, the callback is guarenteed to be invoked only when the 1171<p>As with timers, the callback is guarenteed to be invoked only when the
961time (<code>at</code>) has been passed, but if multiple periodic timers become ready 1172time (<code>at</code>) has been passed, but if multiple periodic timers become ready
962during the same loop iteration then order of execution is undefined.</p> 1173during the same loop iteration then order of execution is undefined.</p>
1174
1175</div>
1176<h3 id="Watcher_Specific_Functions_and_Data_-3">Watcher-Specific Functions and Data Members</h3>
1177<div id="Watcher_Specific_Functions_and_Data_-2">
963<dl> 1178<dl>
964 <dt>ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)</dt> 1179 <dt>ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)</dt>
965 <dt>ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)</dt> 1180 <dt>ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)</dt>
966 <dd> 1181 <dd>
967 <p>Lots of arguments, lets sort it out... There are basically three modes of 1182 <p>Lots of arguments, lets sort it out... There are basically three modes of
968operation, and we will explain them from simplest to complex:</p> 1183operation, and we will explain them from simplest to complex:</p>
969 <p> 1184 <p>
970 <dl> 1185 <dl>
971 <dt>* absolute timer (interval = reschedule_cb = 0)</dt> 1186 <dt>* absolute timer (at = time, interval = reschedule_cb = 0)</dt>
972 <dd> 1187 <dd>
973 <p>In this configuration the watcher triggers an event at the wallclock time 1188 <p>In this configuration the watcher triggers an event at the wallclock time
974<code>at</code> and doesn't repeat. It will not adjust when a time jump occurs, 1189<code>at</code> and doesn't repeat. It will not adjust when a time jump occurs,
975that is, if it is to be run at January 1st 2011 then it will run when the 1190that is, if it is to be run at January 1st 2011 then it will run when the
976system time reaches or surpasses this time.</p> 1191system time reaches or surpasses this time.</p>
977 </dd> 1192 </dd>
978 <dt>* non-repeating interval timer (interval &gt; 0, reschedule_cb = 0)</dt> 1193 <dt>* non-repeating interval timer (at = offset, interval &gt; 0, reschedule_cb = 0)</dt>
979 <dd> 1194 <dd>
980 <p>In this mode the watcher will always be scheduled to time out at the next 1195 <p>In this mode the watcher will always be scheduled to time out at the next
981<code>at + N * interval</code> time (for some integer N) and then repeat, regardless 1196<code>at + N * interval</code> time (for some integer N, which can also be negative)
982of any time jumps.</p> 1197and then repeat, regardless of any time jumps.</p>
983 <p>This can be used to create timers that do not drift with respect to system 1198 <p>This can be used to create timers that do not drift with respect to system
984time:</p> 1199time:</p>
985<pre> ev_periodic_set (&amp;periodic, 0., 3600., 0); 1200<pre> ev_periodic_set (&amp;periodic, 0., 3600., 0);
986 1201
987</pre> 1202</pre>
… …
990full hour (UTC), or more correctly, when the system time is evenly divisible 1205full hour (UTC), or more correctly, when the system time is evenly divisible
991by 3600.</p> 1206by 3600.</p>
992 <p>Another way to think about it (for the mathematically inclined) is that 1207 <p>Another way to think about it (for the mathematically inclined) is that
993<code>ev_periodic</code> will try to run the callback in this mode at the next possible 1208<code>ev_periodic</code> will try to run the callback in this mode at the next possible
994time where <code>time = at (mod interval)</code>, regardless of any time jumps.</p> 1209time where <code>time = at (mod interval)</code>, regardless of any time jumps.</p>
1210 <p>For numerical stability it is preferable that the <code>at</code> value is near
1211<code>ev_now ()</code> (the current time), but there is no range requirement for
1212this value.</p>
995 </dd> 1213 </dd>
996 <dt>* manual reschedule mode (reschedule_cb = callback)</dt> 1214 <dt>* manual reschedule mode (at and interval ignored, reschedule_cb = callback)</dt>
997 <dd> 1215 <dd>
998 <p>In this mode the values for <code>interval</code> and <code>at</code> are both being 1216 <p>In this mode the values for <code>interval</code> and <code>at</code> are both being
999ignored. Instead, each time the periodic watcher gets scheduled, the 1217ignored. Instead, each time the periodic watcher gets scheduled, the
1000reschedule callback will be called with the watcher as first, and the 1218reschedule callback will be called with the watcher as first, and the
1001current time as second argument.</p> 1219current time as second argument.</p>
1002 <p>NOTE: <i>This callback MUST NOT stop or destroy any periodic watcher, 1220 <p>NOTE: <i>This callback MUST NOT stop or destroy any periodic watcher,
1003ever, or make any event loop modifications</i>. If you need to stop it, 1221ever, or make any event loop modifications</i>. If you need to stop it,
1004return <code>now + 1e30</code> (or so, fudge fudge) and stop it afterwards (e.g. by 1222return <code>now + 1e30</code> (or so, fudge fudge) and stop it afterwards (e.g. by
1005starting a prepare watcher).</p> 1223starting an <code>ev_prepare</code> watcher, which is legal).</p>
1006 <p>Its prototype is <code>ev_tstamp (*reschedule_cb)(struct ev_periodic *w, 1224 <p>Its prototype is <code>ev_tstamp (*reschedule_cb)(struct ev_periodic *w,
1007ev_tstamp now)</code>, e.g.:</p> 1225ev_tstamp now)</code>, e.g.:</p>
1008<pre> static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now) 1226<pre> static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now)
1009 { 1227 {
1010 return now + 60.; 1228 return now + 60.;
… …
1031 <p>Simply stops and restarts the periodic watcher again. This is only useful 1249 <p>Simply stops and restarts the periodic watcher again. This is only useful
1032when you changed some parameters or the reschedule callback would return 1250when you changed some parameters or the reschedule callback would return
1033a different time than the last time it was called (e.g. in a crond like 1251a different time than the last time it was called (e.g. in a crond like
1034program when the crontabs have changed).</p> 1252program when the crontabs have changed).</p>
1035 </dd> 1253 </dd>
1254 <dt>ev_tstamp offset [read-write]</dt>
1255 <dd>
1256 <p>When repeating, this contains the offset value, otherwise this is the
1257absolute point in time (the <code>at</code> value passed to <code>ev_periodic_set</code>).</p>
1258 <p>Can be modified any time, but changes only take effect when the periodic
1259timer fires or <code>ev_periodic_again</code> is being called.</p>
1260 </dd>
1036 <dt>ev_tstamp interval [read-write]</dt> 1261 <dt>ev_tstamp interval [read-write]</dt>
1037 <dd> 1262 <dd>
1038 <p>The current interval value. Can be modified any time, but changes only 1263 <p>The current interval value. Can be modified any time, but changes only
1039take effect when the periodic timer fires or <code>ev_periodic_again</code> is being 1264take effect when the periodic timer fires or <code>ev_periodic_again</code> is being
1040called.</p> 1265called.</p>
… …
1044 <p>The current reschedule callback, or <code>0</code>, if this functionality is 1269 <p>The current reschedule callback, or <code>0</code>, if this functionality is
1045switched off. Can be changed any time, but changes only take effect when 1270switched off. Can be changed any time, but changes only take effect when
1046the periodic timer fires or <code>ev_periodic_again</code> is being called.</p> 1271the periodic timer fires or <code>ev_periodic_again</code> is being called.</p>
1047 </dd> 1272 </dd>
1048</dl> 1273</dl>
1049<p>Example: call a callback every hour, or, more precisely, whenever the 1274<p>Example: Call a callback every hour, or, more precisely, whenever the
1050system clock is divisible by 3600. The callback invocation times have 1275system clock is divisible by 3600. The callback invocation times have
1051potentially a lot of jittering, but good long-term stability.</p> 1276potentially a lot of jittering, but good long-term stability.</p>
1052<pre> static void 1277<pre> static void
1053 clock_cb (struct ev_loop *loop, struct ev_io *w, int revents) 1278 clock_cb (struct ev_loop *loop, struct ev_io *w, int revents)
1054 { 1279 {
… …
1058 struct ev_periodic hourly_tick; 1283 struct ev_periodic hourly_tick;
1059 ev_periodic_init (&amp;hourly_tick, clock_cb, 0., 3600., 0); 1284 ev_periodic_init (&amp;hourly_tick, clock_cb, 0., 3600., 0);
1060 ev_periodic_start (loop, &amp;hourly_tick); 1285 ev_periodic_start (loop, &amp;hourly_tick);
1061 1286
1062</pre> 1287</pre>
1063<p>Example: the same as above, but use a reschedule callback to do it:</p> 1288<p>Example: The same as above, but use a reschedule callback to do it:</p>
1064<pre> #include &lt;math.h&gt; 1289<pre> #include &lt;math.h&gt;
1065 1290
1066 static ev_tstamp 1291 static ev_tstamp
1067 my_scheduler_cb (struct ev_periodic *w, ev_tstamp now) 1292 my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)
1068 { 1293 {
… …
1070 } 1295 }
1071 1296
1072 ev_periodic_init (&amp;hourly_tick, clock_cb, 0., 0., my_scheduler_cb); 1297 ev_periodic_init (&amp;hourly_tick, clock_cb, 0., 0., my_scheduler_cb);
1073 1298
1074</pre> 1299</pre>
1075<p>Example: call a callback every hour, starting now:</p> 1300<p>Example: Call a callback every hour, starting now:</p>
1076<pre> struct ev_periodic hourly_tick; 1301<pre> struct ev_periodic hourly_tick;
1077 ev_periodic_init (&amp;hourly_tick, clock_cb, 1302 ev_periodic_init (&amp;hourly_tick, clock_cb,
1078 fmod (ev_now (loop), 3600.), 3600., 0); 1303 fmod (ev_now (loop), 3600.), 3600., 0);
1079 ev_periodic_start (loop, &amp;hourly_tick); 1304 ev_periodic_start (loop, &amp;hourly_tick);
1080 1305
… …
1094first watcher gets started will libev actually register a signal watcher 1319first watcher gets started will libev actually register a signal watcher
1095with the kernel (thus it coexists with your own signal handlers as long 1320with the kernel (thus it coexists with your own signal handlers as long
1096as you don't register any with libev). Similarly, when the last signal 1321as you don't register any with libev). Similarly, when the last signal
1097watcher for a signal is stopped libev will reset the signal handler to 1322watcher for a signal is stopped libev will reset the signal handler to
1098SIG_DFL (regardless of what it was set to before).</p> 1323SIG_DFL (regardless of what it was set to before).</p>
1324
1325</div>
1326<h3 id="Watcher_Specific_Functions_and_Data_-4">Watcher-Specific Functions and Data Members</h3>
1327<div id="Watcher_Specific_Functions_and_Data_-2-2">
1099<dl> 1328<dl>
1100 <dt>ev_signal_init (ev_signal *, callback, int signum)</dt> 1329 <dt>ev_signal_init (ev_signal *, callback, int signum)</dt>
1101 <dt>ev_signal_set (ev_signal *, int signum)</dt> 1330 <dt>ev_signal_set (ev_signal *, int signum)</dt>
1102 <dd> 1331 <dd>
1103 <p>Configures the watcher to trigger on the given signal number (usually one 1332 <p>Configures the watcher to trigger on the given signal number (usually one
… …
1116</div> 1345</div>
1117<h2 id="code_ev_child_code_watch_out_for_pro"><code>ev_child</code> - watch out for process status changes</h2> 1346<h2 id="code_ev_child_code_watch_out_for_pro"><code>ev_child</code> - watch out for process status changes</h2>
1118<div id="code_ev_child_code_watch_out_for_pro-2"> 1347<div id="code_ev_child_code_watch_out_for_pro-2">
1119<p>Child watchers trigger when your process receives a SIGCHLD in response to 1348<p>Child watchers trigger when your process receives a SIGCHLD in response to
1120some child status changes (most typically when a child of yours dies).</p> 1349some child status changes (most typically when a child of yours dies).</p>
1350
1351</div>
1352<h3 id="Watcher_Specific_Functions_and_Data_-5">Watcher-Specific Functions and Data Members</h3>
1353<div id="Watcher_Specific_Functions_and_Data_-2-3">
1121<dl> 1354<dl>
1122 <dt>ev_child_init (ev_child *, callback, int pid)</dt> 1355 <dt>ev_child_init (ev_child *, callback, int pid)</dt>
1123 <dt>ev_child_set (ev_child *, int pid)</dt> 1356 <dt>ev_child_set (ev_child *, int pid)</dt>
1124 <dd> 1357 <dd>
1125 <p>Configures the watcher to wait for status changes of process <code>pid</code> (or 1358 <p>Configures the watcher to wait for status changes of process <code>pid</code> (or
… …
1141 <dd> 1374 <dd>
1142 <p>The process exit/trace status caused by <code>rpid</code> (see your systems 1375 <p>The process exit/trace status caused by <code>rpid</code> (see your systems
1143<code>waitpid</code> and <code>sys/wait.h</code> documentation for details).</p> 1376<code>waitpid</code> and <code>sys/wait.h</code> documentation for details).</p>
1144 </dd> 1377 </dd>
1145</dl> 1378</dl>
1146<p>Example: try to exit cleanly on SIGINT and SIGTERM.</p> 1379<p>Example: Try to exit cleanly on SIGINT and SIGTERM.</p>
1147<pre> static void 1380<pre> static void
1148 sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) 1381 sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents)
1149 { 1382 {
1150 ev_unloop (loop, EVUNLOOP_ALL); 1383 ev_unloop (loop, EVUNLOOP_ALL);
1151 } 1384 }
… …
1168<p>The path does not need to exist: changing from &quot;path exists&quot; to &quot;path does 1401<p>The path does not need to exist: changing from &quot;path exists&quot; to &quot;path does
1169not exist&quot; is a status change like any other. The condition &quot;path does 1402not exist&quot; is a status change like any other. The condition &quot;path does
1170not exist&quot; is signified by the <code>st_nlink</code> field being zero (which is 1403not exist&quot; is signified by the <code>st_nlink</code> field being zero (which is
1171otherwise always forced to be at least one) and all the other fields of 1404otherwise always forced to be at least one) and all the other fields of
1172the stat buffer having unspecified contents.</p> 1405the stat buffer having unspecified contents.</p>
1406<p>The path <i>should</i> be absolute and <i>must not</i> end in a slash. If it is
1407relative and your working directory changes, the behaviour is undefined.</p>
1173<p>Since there is no standard to do this, the portable implementation simply 1408<p>Since there is no standard to do this, the portable implementation simply
1174calls <code>stat (2)</code> regulalry on the path to see if it changed somehow. You 1409calls <code>stat (2)</code> regularly on the path to see if it changed somehow. You
1175can specify a recommended polling interval for this case. If you specify 1410can specify a recommended polling interval for this case. If you specify
1176a polling interval of <code>0</code> (highly recommended!) then a <i>suitable, 1411a polling interval of <code>0</code> (highly recommended!) then a <i>suitable,
1177unspecified default</i> value will be used (which you can expect to be around 1412unspecified default</i> value will be used (which you can expect to be around
1178five seconds, although this might change dynamically). Libev will also 1413five seconds, although this might change dynamically). Libev will also
1179impose a minimum interval which is currently around <code>0.1</code>, but thats 1414impose a minimum interval which is currently around <code>0.1</code>, but thats
1180usually overkill.</p> 1415usually overkill.</p>
1181<p>This watcher type is not meant for massive numbers of stat watchers, 1416<p>This watcher type is not meant for massive numbers of stat watchers,
1182as even with OS-supported change notifications, this can be 1417as even with OS-supported change notifications, this can be
1183resource-intensive.</p> 1418resource-intensive.</p>
1184<p>At the time of this writing, no specific OS backends are implemented, but 1419<p>At the time of this writing, only the Linux inotify interface is
1185if demand increases, at least a kqueue and inotify backend will be added.</p> 1420implemented (implementing kqueue support is left as an exercise for the
1421reader). Inotify will be used to give hints only and should not change the
1422semantics of <code>ev_stat</code> watchers, which means that libev sometimes needs
1423to fall back to regular polling again even with inotify, but changes are
1424usually detected immediately, and if the file exists there will be no
1425polling.</p>
1426
1427</div>
1428<h3 id="Watcher_Specific_Functions_and_Data_-6">Watcher-Specific Functions and Data Members</h3>
1429<div id="Watcher_Specific_Functions_and_Data_-2-4">
1186<dl> 1430<dl>
1187 <dt>ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)</dt> 1431 <dt>ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)</dt>
1188 <dt>ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)</dt> 1432 <dt>ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)</dt>
1189 <dd> 1433 <dd>
1190 <p>Configures the watcher to wait for status changes of the given 1434 <p>Configures the watcher to wait for status changes of the given
… …
1253</pre> 1497</pre>
1254 1498
1255</div> 1499</div>
1256<h2 id="code_ev_idle_code_when_you_ve_got_no"><code>ev_idle</code> - when you've got nothing better to do...</h2> 1500<h2 id="code_ev_idle_code_when_you_ve_got_no"><code>ev_idle</code> - when you've got nothing better to do...</h2>
1257<div id="code_ev_idle_code_when_you_ve_got_no-2"> 1501<div id="code_ev_idle_code_when_you_ve_got_no-2">
1258<p>Idle watchers trigger events when there are no other events are pending 1502<p>Idle watchers trigger events when no other events of the same or higher
1259(prepare, check and other idle watchers do not count). That is, as long 1503priority are pending (prepare, check and other idle watchers do not
1260as your process is busy handling sockets or timeouts (or even signals, 1504count).</p>
1261imagine) it will not be triggered. But when your process is idle all idle 1505<p>That is, as long as your process is busy handling sockets or timeouts
1262watchers are being called again and again, once per event loop iteration - 1506(or even signals, imagine) of the same or higher priority it will not be
1507triggered. But when your process is idle (or only lower-priority watchers
1508are pending), the idle watchers are being called once per event loop
1263until stopped, that is, or your process receives more events and becomes 1509iteration - until stopped, that is, or your process receives more events
1264busy.</p> 1510and becomes busy again with higher priority stuff.</p>
1265<p>The most noteworthy effect is that as long as any idle watchers are 1511<p>The most noteworthy effect is that as long as any idle watchers are
1266active, the process will not block when waiting for new events.</p> 1512active, the process will not block when waiting for new events.</p>
1267<p>Apart from keeping your process non-blocking (which is a useful 1513<p>Apart from keeping your process non-blocking (which is a useful
1268effect on its own sometimes), idle watchers are a good place to do 1514effect on its own sometimes), idle watchers are a good place to do
1269&quot;pseudo-background processing&quot;, or delay processing stuff to after the 1515&quot;pseudo-background processing&quot;, or delay processing stuff to after the
1270event loop has handled all outstanding events.</p> 1516event loop has handled all outstanding events.</p>
1517
1518</div>
1519<h3 id="Watcher_Specific_Functions_and_Data_-7">Watcher-Specific Functions and Data Members</h3>
1520<div id="Watcher_Specific_Functions_and_Data_-2-5">
1271<dl> 1521<dl>
1272 <dt>ev_idle_init (ev_signal *, callback)</dt> 1522 <dt>ev_idle_init (ev_signal *, callback)</dt>
1273 <dd> 1523 <dd>
1274 <p>Initialises and configures the idle watcher - it has no parameters of any 1524 <p>Initialises and configures the idle watcher - it has no parameters of any
1275kind. There is a <code>ev_idle_set</code> macro, but using it is utterly pointless, 1525kind. There is a <code>ev_idle_set</code> macro, but using it is utterly pointless,
1276believe me.</p> 1526believe me.</p>
1277 </dd> 1527 </dd>
1278</dl> 1528</dl>
1279<p>Example: dynamically allocate an <code>ev_idle</code>, start it, and in the 1529<p>Example: Dynamically allocate an <code>ev_idle</code> watcher, start it, and in the
1280callback, free it. Alos, use no error checking, as usual.</p> 1530callback, free it. Also, use no error checking, as usual.</p>
1281<pre> static void 1531<pre> static void
1282 idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents) 1532 idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents)
1283 { 1533 {
1284 free (w); 1534 free (w);
1285 // now do something you wanted to do when the program has 1535 // now do something you wanted to do when the program has
… …
1329are ready to run (it's actually more complicated: it only runs coroutines 1579are ready to run (it's actually more complicated: it only runs coroutines
1330with priority higher than or equal to the event loop and one coroutine 1580with priority higher than or equal to the event loop and one coroutine
1331of lower priority, but only once, using idle watchers to keep the event 1581of lower priority, but only once, using idle watchers to keep the event
1332loop from blocking if lower-priority coroutines are active, thus mapping 1582loop from blocking if lower-priority coroutines are active, thus mapping
1333low-priority coroutines to idle/background tasks).</p> 1583low-priority coroutines to idle/background tasks).</p>
1584<p>It is recommended to give <code>ev_check</code> watchers highest (<code>EV_MAXPRI</code>)
1585priority, to ensure that they are being run before any other watchers
1586after the poll. Also, <code>ev_check</code> watchers (and <code>ev_prepare</code> watchers,
1587too) should not activate (&quot;feed&quot;) events into libev. While libev fully
1588supports this, they will be called before other <code>ev_check</code> watchers did
1589their job. As <code>ev_check</code> watchers are often used to embed other event
1590loops those other event loops might be in an unusable state until their
1591<code>ev_check</code> watcher ran (always remind yourself to coexist peacefully with
1592others).</p>
1593
1594</div>
1595<h3 id="Watcher_Specific_Functions_and_Data_-8">Watcher-Specific Functions and Data Members</h3>
1596<div id="Watcher_Specific_Functions_and_Data_-2-6">
1334<dl> 1597<dl>
1335 <dt>ev_prepare_init (ev_prepare *, callback)</dt> 1598 <dt>ev_prepare_init (ev_prepare *, callback)</dt>
1336 <dt>ev_check_init (ev_check *, callback)</dt> 1599 <dt>ev_check_init (ev_check *, callback)</dt>
1337 <dd> 1600 <dd>
1338 <p>Initialises and configures the prepare or check watcher - they have no 1601 <p>Initialises and configures the prepare or check watcher - they have no
1339parameters of any kind. There are <code>ev_prepare_set</code> and <code>ev_check_set</code> 1602parameters of any kind. There are <code>ev_prepare_set</code> and <code>ev_check_set</code>
1340macros, but using them is utterly, utterly and completely pointless.</p> 1603macros, but using them is utterly, utterly and completely pointless.</p>
1341 </dd> 1604 </dd>
1342</dl> 1605</dl>
1343<p>Example: To include a library such as adns, you would add IO watchers 1606<p>There are a number of principal ways to embed other event loops or modules
1344and a timeout watcher in a prepare handler, as required by libadns, and 1607into libev. Here are some ideas on how to include libadns into libev
1608(there is a Perl module named <code>EV::ADNS</code> that does this, which you could
1609use for an actually working example. Another Perl module named <code>EV::Glib</code>
1610embeds a Glib main context into libev, and finally, <code>Glib::EV</code> embeds EV
1611into the Glib event loop).</p>
1612<p>Method 1: Add IO watchers and a timeout watcher in a prepare handler,
1345in a check watcher, destroy them and call into libadns. What follows is 1613and in a check watcher, destroy them and call into libadns. What follows
1346pseudo-code only of course:</p> 1614is pseudo-code only of course. This requires you to either use a low
1615priority for the check watcher or use <code>ev_clear_pending</code> explicitly, as
1616the callbacks for the IO/timeout watchers might not have been called yet.</p>
1347<pre> static ev_io iow [nfd]; 1617<pre> static ev_io iow [nfd];
1348 static ev_timer tw; 1618 static ev_timer tw;
1349 1619
1350 static void 1620 static void
1351 io_cb (ev_loop *loop, ev_io *w, int revents) 1621 io_cb (ev_loop *loop, ev_io *w, int revents)
1352 { 1622 {
1353 // set the relevant poll flags
1354 // could also call adns_processreadable etc. here
1355 struct pollfd *fd = (struct pollfd *)w-&gt;data;
1356 if (revents &amp; EV_READ ) fd-&gt;revents |= fd-&gt;events &amp; POLLIN;
1357 if (revents &amp; EV_WRITE) fd-&gt;revents |= fd-&gt;events &amp; POLLOUT;
1358 } 1623 }
1359 1624
1360 // create io watchers for each fd and a timer before blocking 1625 // create io watchers for each fd and a timer before blocking
1361 static void 1626 static void
1362 adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) 1627 adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents)
1363 { 1628 {
1364 int timeout = 3600000;truct pollfd fds [nfd]; 1629 int timeout = 3600000;
1630 struct pollfd fds [nfd];
1365 // actual code will need to loop here and realloc etc. 1631 // actual code will need to loop here and realloc etc.
1366 adns_beforepoll (ads, fds, &amp;nfd, &amp;timeout, timeval_from (ev_time ())); 1632 adns_beforepoll (ads, fds, &amp;nfd, &amp;timeout, timeval_from (ev_time ()));
1367 1633
1368 /* the callback is illegal, but won't be called as we stop during check */ 1634 /* the callback is illegal, but won't be called as we stop during check */
1369 ev_timer_init (&amp;tw, 0, timeout * 1e-3); 1635 ev_timer_init (&amp;tw, 0, timeout * 1e-3);
1370 ev_timer_start (loop, &amp;tw); 1636 ev_timer_start (loop, &amp;tw);
1371 1637
1372 // create on ev_io per pollfd 1638 // create one ev_io per pollfd
1373 for (int i = 0; i &lt; nfd; ++i) 1639 for (int i = 0; i &lt; nfd; ++i)
1374 { 1640 {
1375 ev_io_init (iow + i, io_cb, fds [i].fd, 1641 ev_io_init (iow + i, io_cb, fds [i].fd,
1376 ((fds [i].events &amp; POLLIN ? EV_READ : 0) 1642 ((fds [i].events &amp; POLLIN ? EV_READ : 0)
1377 | (fds [i].events &amp; POLLOUT ? EV_WRITE : 0))); 1643 | (fds [i].events &amp; POLLOUT ? EV_WRITE : 0)));
1378 1644
1379 fds [i].revents = 0; 1645 fds [i].revents = 0;
1380 iow [i].data = fds + i;
1381 ev_io_start (loop, iow + i); 1646 ev_io_start (loop, iow + i);
1382 } 1647 }
1383 } 1648 }
1384 1649
1385 // stop all watchers after blocking 1650 // stop all watchers after blocking
… …
1387 adns_check_cb (ev_loop *loop, ev_check *w, int revents) 1652 adns_check_cb (ev_loop *loop, ev_check *w, int revents)
1388 { 1653 {
1389 ev_timer_stop (loop, &amp;tw); 1654 ev_timer_stop (loop, &amp;tw);
1390 1655
1391 for (int i = 0; i &lt; nfd; ++i) 1656 for (int i = 0; i &lt; nfd; ++i)
1657 {
1658 // set the relevant poll flags
1659 // could also call adns_processreadable etc. here
1660 struct pollfd *fd = fds + i;
1661 int revents = ev_clear_pending (iow + i);
1662 if (revents &amp; EV_READ ) fd-&gt;revents |= fd-&gt;events &amp; POLLIN;
1663 if (revents &amp; EV_WRITE) fd-&gt;revents |= fd-&gt;events &amp; POLLOUT;
1664
1665 // now stop the watcher
1392 ev_io_stop (loop, iow + i); 1666 ev_io_stop (loop, iow + i);
1667 }
1393 1668
1394 adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop)); 1669 adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));
1670 }
1671
1672</pre>
1673<p>Method 2: This would be just like method 1, but you run <code>adns_afterpoll</code>
1674in the prepare watcher and would dispose of the check watcher.</p>
1675<p>Method 3: If the module to be embedded supports explicit event
1676notification (adns does), you can also make use of the actual watcher
1677callbacks, and only destroy/create the watchers in the prepare watcher.</p>
1678<pre> static void
1679 timer_cb (EV_P_ ev_timer *w, int revents)
1680 {
1681 adns_state ads = (adns_state)w-&gt;data;
1682 update_now (EV_A);
1683
1684 adns_processtimeouts (ads, &amp;tv_now);
1685 }
1686
1687 static void
1688 io_cb (EV_P_ ev_io *w, int revents)
1689 {
1690 adns_state ads = (adns_state)w-&gt;data;
1691 update_now (EV_A);
1692
1693 if (revents &amp; EV_READ ) adns_processreadable (ads, w-&gt;fd, &amp;tv_now);
1694 if (revents &amp; EV_WRITE) adns_processwriteable (ads, w-&gt;fd, &amp;tv_now);
1695 }
1696
1697 // do not ever call adns_afterpoll
1698
1699</pre>
1700<p>Method 4: Do not use a prepare or check watcher because the module you
1701want to embed is too inflexible to support it. Instead, youc na override
1702their poll function. The drawback with this solution is that the main
1703loop is now no longer controllable by EV. The <code>Glib::EV</code> module does
1704this.</p>
1705<pre> static gint
1706 event_poll_func (GPollFD *fds, guint nfds, gint timeout)
1707 {
1708 int got_events = 0;
1709
1710 for (n = 0; n &lt; nfds; ++n)
1711 // create/start io watcher that sets the relevant bits in fds[n] and increment got_events
1712
1713 if (timeout &gt;= 0)
1714 // create/start timer
1715
1716 // poll
1717 ev_loop (EV_A_ 0);
1718
1719 // stop timer again
1720 if (timeout &gt;= 0)
1721 ev_timer_stop (EV_A_ &amp;to);
1722
1723 // stop io watchers again - their callbacks should have set
1724 for (n = 0; n &lt; nfds; ++n)
1725 ev_io_stop (EV_A_ iow [n]);
1726
1727 return got_events;
1395 } 1728 }
1396 1729
1397 1730
1398 1731
1399 1732
… …
1460 } 1793 }
1461 else 1794 else
1462 loop_lo = loop_hi; 1795 loop_lo = loop_hi;
1463 1796
1464</pre> 1797</pre>
1798
1799</div>
1800<h3 id="Watcher_Specific_Functions_and_Data_-9">Watcher-Specific Functions and Data Members</h3>
1801<div id="Watcher_Specific_Functions_and_Data_-2-7">
1465<dl> 1802<dl>
1466 <dt>ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)</dt> 1803 <dt>ev_embed_init (ev_embed *, callback, struct ev_loop *embedded_loop)</dt>
1467 <dt>ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)</dt> 1804 <dt>ev_embed_set (ev_embed *, callback, struct ev_loop *embedded_loop)</dt>
1468 <dd> 1805 <dd>
1469 <p>Configures the watcher to embed the given loop, which must be 1806 <p>Configures the watcher to embed the given loop, which must be
… …
1496<code>ev_default_fork</code> or <code>ev_loop_fork</code>). The invocation is done before the 1833<code>ev_default_fork</code> or <code>ev_loop_fork</code>). The invocation is done before the
1497event loop blocks next and before <code>ev_check</code> watchers are being called, 1834event loop blocks next and before <code>ev_check</code> watchers are being called,
1498and only in the child after the fork. If whoever good citizen calling 1835and only in the child after the fork. If whoever good citizen calling
1499<code>ev_default_fork</code> cheats and calls it in the wrong process, the fork 1836<code>ev_default_fork</code> cheats and calls it in the wrong process, the fork
1500handlers will be invoked, too, of course.</p> 1837handlers will be invoked, too, of course.</p>
1838
1839</div>
1840<h3 id="Watcher_Specific_Functions_and_Data_-10">Watcher-Specific Functions and Data Members</h3>
1841<div id="Watcher_Specific_Functions_and_Data_-2-8">
1501<dl> 1842<dl>
1502 <dt>ev_fork_init (ev_signal *, callback)</dt> 1843 <dt>ev_fork_init (ev_signal *, callback)</dt>
1503 <dd> 1844 <dd>
1504 <p>Initialises and configures the fork watcher - it has no parameters of any 1845 <p>Initialises and configures the fork watcher - it has no parameters of any
1505kind. There is a <code>ev_fork_set</code> macro, but using it is utterly pointless, 1846kind. There is a <code>ev_fork_set</code> macro, but using it is utterly pointless,
… …
1510 1851
1511 1852
1512 1853
1513 1854
1514</div> 1855</div>
1515<h1 id="OTHER_FUNCTIONS">OTHER FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p> 1856<h1 id="OTHER_FUNCTIONS">OTHER FUNCTIONS</h1>
1516<div id="OTHER_FUNCTIONS_CONTENT"> 1857<div id="OTHER_FUNCTIONS_CONTENT">
1517<p>There are some other functions of possible interest. Described. Here. Now.</p> 1858<p>There are some other functions of possible interest. Described. Here. Now.</p>
1518<dl> 1859<dl>
1519 <dt>ev_once (loop, int fd, int events, ev_tstamp timeout, callback)</dt> 1860 <dt>ev_once (loop, int fd, int events, ev_tstamp timeout, callback)</dt>
1520 <dd> 1861 <dd>
… …
1567 1908
1568 1909
1569 1910
1570 1911
1571</div> 1912</div>
1572<h1 id="LIBEVENT_EMULATION">LIBEVENT EMULATION</h1><p><a href="#TOP" class="toplink">Top</a></p> 1913<h1 id="LIBEVENT_EMULATION">LIBEVENT EMULATION</h1>
1573<div id="LIBEVENT_EMULATION_CONTENT"> 1914<div id="LIBEVENT_EMULATION_CONTENT">
1574<p>Libev offers a compatibility emulation layer for libevent. It cannot 1915<p>Libev offers a compatibility emulation layer for libevent. It cannot
1575emulate the internals of libevent, so here are some usage hints:</p> 1916emulate the internals of libevent, so here are some usage hints:</p>
1576<dl> 1917<dl>
1577 <dt>* Use it by including &lt;event.h&gt;, as usual.</dt> 1918 <dt>* Use it by including &lt;event.h&gt;, as usual.</dt>
… …
1587 <dt>* The libev emulation is <i>not</i> ABI compatible to libevent, you need 1928 <dt>* The libev emulation is <i>not</i> ABI compatible to libevent, you need
1588to use the libev header file and library.</dt> 1929to use the libev header file and library.</dt>
1589</dl> 1930</dl>
1590 1931
1591</div> 1932</div>
1592<h1 id="C_SUPPORT">C++ SUPPORT</h1><p><a href="#TOP" class="toplink">Top</a></p> 1933<h1 id="C_SUPPORT">C++ SUPPORT</h1>
1593<div id="C_SUPPORT_CONTENT"> 1934<div id="C_SUPPORT_CONTENT">
1594<p>Libev comes with some simplistic wrapper classes for C++ that mainly allow 1935<p>Libev comes with some simplistic wrapper classes for C++ that mainly allow
1595you to use some convinience methods to start/stop watchers and also change 1936you to use some convinience methods to start/stop watchers and also change
1596the callback model to a model using method callbacks on objects.</p> 1937the callback model to a model using method callbacks on objects.</p>
1597<p>To use it,</p> 1938<p>To use it,</p>
1598<pre> #include &lt;ev++.h&gt; 1939<pre> #include &lt;ev++.h&gt;
1599 1940
1600</pre> 1941</pre>
1601<p>(it is not installed by default). This automatically includes <cite>ev.h</cite> 1942<p>This automatically includes <cite>ev.h</cite> and puts all of its definitions (many
1602and puts all of its definitions (many of them macros) into the global 1943of them macros) into the global namespace. All C++ specific things are
1603namespace. All C++ specific things are put into the <code>ev</code> namespace.</p> 1944put into the <code>ev</code> namespace. It should support all the same embedding
1604<p>It should support all the same embedding options as <cite>ev.h</cite>, most notably 1945options as <cite>ev.h</cite>, most notably <code>EV_MULTIPLICITY</code>.</p>
1605<code>EV_MULTIPLICITY</code>.</p> 1946<p>Care has been taken to keep the overhead low. The only data member the C++
1947classes add (compared to plain C-style watchers) is the event loop pointer
1948that the watcher is associated with (or no additional members at all if
1949you disable <code>EV_MULTIPLICITY</code> when embedding libev).</p>
1950<p>Currently, functions, and static and non-static member functions can be
1951used as callbacks. Other types should be easy to add as long as they only
1952need one additional pointer for context. If you need support for other
1953types of functors please contact the author (preferably after implementing
1954it).</p>
1606<p>Here is a list of things available in the <code>ev</code> namespace:</p> 1955<p>Here is a list of things available in the <code>ev</code> namespace:</p>
1607<dl> 1956<dl>
1608 <dt><code>ev::READ</code>, <code>ev::WRITE</code> etc.</dt> 1957 <dt><code>ev::READ</code>, <code>ev::WRITE</code> etc.</dt>
1609 <dd> 1958 <dd>
1610 <p>These are just enum values with the same values as the <code>EV_READ</code> etc. 1959 <p>These are just enum values with the same values as the <code>EV_READ</code> etc.
… …
1621which is called <code>ev::sig</code> to avoid clashes with the <code>signal</code> macro 1970which is called <code>ev::sig</code> to avoid clashes with the <code>signal</code> macro
1622defines by many implementations.</p> 1971defines by many implementations.</p>
1623 <p>All of those classes have these methods:</p> 1972 <p>All of those classes have these methods:</p>
1624 <p> 1973 <p>
1625 <dl> 1974 <dl>
1626 <dt>ev::TYPE::TYPE (object *, object::method *)</dt> 1975 <dt>ev::TYPE::TYPE ()</dt>
1627 <dt>ev::TYPE::TYPE (object *, object::method *, struct ev_loop *)</dt> 1976 <dt>ev::TYPE::TYPE (struct ev_loop *)</dt>
1628 <dt>ev::TYPE::~TYPE</dt> 1977 <dt>ev::TYPE::~TYPE</dt>
1629 <dd> 1978 <dd>
1630 <p>The constructor takes a pointer to an object and a method pointer to 1979 <p>The constructor (optionally) takes an event loop to associate the watcher
1631the event handler callback to call in this class. The constructor calls 1980with. If it is omitted, it will use <code>EV_DEFAULT</code>.</p>
1632<code>ev_init</code> for you, which means you have to call the <code>set</code> method 1981 <p>The constructor calls <code>ev_init</code> for you, which means you have to call the
1633before starting it. If you do not specify a loop then the constructor 1982<code>set</code> method before starting it.</p>
1634automatically associates the default loop with this watcher.</p> 1983 <p>It will not set a callback, however: You have to call the templated <code>set</code>
1984method to set a callback before you can start the watcher.</p>
1985 <p>(The reason why you have to use a method is a limitation in C++ which does
1986not allow explicit template arguments for constructors).</p>
1635 <p>The destructor automatically stops the watcher if it is active.</p> 1987 <p>The destructor automatically stops the watcher if it is active.</p>
1988 </dd>
1989 <dt>w-&gt;set&lt;class, &amp;class::method&gt; (object *)</dt>
1990 <dd>
1991 <p>This method sets the callback method to call. The method has to have a
1992signature of <code>void (*)(ev_TYPE &amp;, int)</code>, it receives the watcher as
1993first argument and the <code>revents</code> as second. The object must be given as
1994parameter and is stored in the <code>data</code> member of the watcher.</p>
1995 <p>This method synthesizes efficient thunking code to call your method from
1996the C callback that libev requires. If your compiler can inline your
1997callback (i.e. it is visible to it at the place of the <code>set</code> call and
1998your compiler is good :), then the method will be fully inlined into the
1999thunking function, making it as fast as a direct C callback.</p>
2000 <p>Example: simple class declaration and watcher initialisation</p>
2001<pre> struct myclass
2002 {
2003 void io_cb (ev::io &amp;w, int revents) { }
2004 }
2005
2006 myclass obj;
2007 ev::io iow;
2008 iow.set &lt;myclass, &amp;myclass::io_cb&gt; (&amp;obj);
2009
2010</pre>
2011 </dd>
2012 <dt>w-&gt;set&lt;function&gt; (void *data = 0)</dt>
2013 <dd>
2014 <p>Also sets a callback, but uses a static method or plain function as
2015callback. The optional <code>data</code> argument will be stored in the watcher's
2016<code>data</code> member and is free for you to use.</p>
2017 <p>The prototype of the <code>function</code> must be <code>void (*)(ev::TYPE &amp;w, int)</code>.</p>
2018 <p>See the method-<code>set</code> above for more details.</p>
2019 <p>Example:</p>
2020<pre> static void io_cb (ev::io &amp;w, int revents) { }
2021 iow.set &lt;io_cb&gt; ();
2022
2023</pre>
1636 </dd> 2024 </dd>
1637 <dt>w-&gt;set (struct ev_loop *)</dt> 2025 <dt>w-&gt;set (struct ev_loop *)</dt>
1638 <dd> 2026 <dd>
1639 <p>Associates a different <code>struct ev_loop</code> with this watcher. You can only 2027 <p>Associates a different <code>struct ev_loop</code> with this watcher. You can only
1640do this when the watcher is inactive (and not pending either).</p> 2028do this when the watcher is inactive (and not pending either).</p>
1641 </dd> 2029 </dd>
1642 <dt>w-&gt;set ([args])</dt> 2030 <dt>w-&gt;set ([args])</dt>
1643 <dd> 2031 <dd>
1644 <p>Basically the same as <code>ev_TYPE_set</code>, with the same args. Must be 2032 <p>Basically the same as <code>ev_TYPE_set</code>, with the same args. Must be
1645called at least once. Unlike the C counterpart, an active watcher gets 2033called at least once. Unlike the C counterpart, an active watcher gets
1646automatically stopped and restarted.</p> 2034automatically stopped and restarted when reconfiguring it with this
2035method.</p>
1647 </dd> 2036 </dd>
1648 <dt>w-&gt;start ()</dt> 2037 <dt>w-&gt;start ()</dt>
1649 <dd> 2038 <dd>
1650 <p>Starts the watcher. Note that there is no <code>loop</code> argument as the 2039 <p>Starts the watcher. Note that there is no <code>loop</code> argument, as the
1651constructor already takes the loop.</p> 2040constructor already stores the event loop.</p>
1652 </dd> 2041 </dd>
1653 <dt>w-&gt;stop ()</dt> 2042 <dt>w-&gt;stop ()</dt>
1654 <dd> 2043 <dd>
1655 <p>Stops the watcher if it is active. Again, no <code>loop</code> argument.</p> 2044 <p>Stops the watcher if it is active. Again, no <code>loop</code> argument.</p>
1656 </dd> 2045 </dd>
… …
1680 2069
1681 myclass (); 2070 myclass ();
1682 } 2071 }
1683 2072
1684 myclass::myclass (int fd) 2073 myclass::myclass (int fd)
1685 : io (this, &amp;myclass::io_cb),
1686 idle (this, &amp;myclass::idle_cb)
1687 { 2074 {
2075 io .set &lt;myclass, &amp;myclass::io_cb &gt; (this);
2076 idle.set &lt;myclass, &amp;myclass::idle_cb&gt; (this);
2077
1688 io.start (fd, ev::READ); 2078 io.start (fd, ev::READ);
1689 } 2079 }
1690 2080
1691 2081
1692 2082
1693 2083
1694</pre> 2084</pre>
1695 2085
1696</div> 2086</div>
1697<h1 id="MACRO_MAGIC">MACRO MAGIC</h1><p><a href="#TOP" class="toplink">Top</a></p> 2087<h1 id="MACRO_MAGIC">MACRO MAGIC</h1>
1698<div id="MACRO_MAGIC_CONTENT"> 2088<div id="MACRO_MAGIC_CONTENT">
1699<p>Libev can be compiled with a variety of options, the most fundemantal is 2089<p>Libev can be compiled with a variety of options, the most fundemantal is
1700<code>EV_MULTIPLICITY</code>. This option determines wether (most) functions and 2090<code>EV_MULTIPLICITY</code>. This option determines whether (most) functions and
1701callbacks have an initial <code>struct ev_loop *</code> argument.</p> 2091callbacks have an initial <code>struct ev_loop *</code> argument.</p>
1702<p>To make it easier to write programs that cope with either variant, the 2092<p>To make it easier to write programs that cope with either variant, the
1703following macros are defined:</p> 2093following macros are defined:</p>
1704<dl> 2094<dl>
1705 <dt><code>EV_A</code>, <code>EV_A_</code></dt> 2095 <dt><code>EV_A</code>, <code>EV_A_</code></dt>
… …
1734 <dd> 2124 <dd>
1735 <p>Similar to the other two macros, this gives you the value of the default 2125 <p>Similar to the other two macros, this gives you the value of the default
1736loop, if multiple loops are supported (&quot;ev loop default&quot;).</p> 2126loop, if multiple loops are supported (&quot;ev loop default&quot;).</p>
1737 </dd> 2127 </dd>
1738</dl> 2128</dl>
1739<p>Example: Declare and initialise a check watcher, working regardless of 2129<p>Example: Declare and initialise a check watcher, utilising the above
1740wether multiple loops are supported or not.</p> 2130macros so it will work regardless of whether multiple loops are supported
2131or not.</p>
1741<pre> static void 2132<pre> static void
1742 check_cb (EV_P_ ev_timer *w, int revents) 2133 check_cb (EV_P_ ev_timer *w, int revents)
1743 { 2134 {
1744 ev_check_stop (EV_A_ w); 2135 ev_check_stop (EV_A_ w);
1745 } 2136 }
… …
1747 ev_check check; 2138 ev_check check;
1748 ev_check_init (&amp;check, check_cb); 2139 ev_check_init (&amp;check, check_cb);
1749 ev_check_start (EV_DEFAULT_ &amp;check); 2140 ev_check_start (EV_DEFAULT_ &amp;check);
1750 ev_loop (EV_DEFAULT_ 0); 2141 ev_loop (EV_DEFAULT_ 0);
1751 2142
1752
1753
1754
1755</pre> 2143</pre>
1756 2144
1757</div> 2145</div>
1758<h1 id="EMBEDDING">EMBEDDING</h1><p><a href="#TOP" class="toplink">Top</a></p> 2146<h1 id="EMBEDDING">EMBEDDING</h1>
1759<div id="EMBEDDING_CONTENT"> 2147<div id="EMBEDDING_CONTENT">
1760<p>Libev can (and often is) directly embedded into host 2148<p>Libev can (and often is) directly embedded into host
1761applications. Examples of applications that embed it include the Deliantra 2149applications. Examples of applications that embed it include the Deliantra
1762Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe) 2150Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe)
1763and rxvt-unicode.</p> 2151and rxvt-unicode.</p>
… …
1800 ev_vars.h 2188 ev_vars.h
1801 ev_wrap.h 2189 ev_wrap.h
1802 2190
1803 ev_win32.c required on win32 platforms only 2191 ev_win32.c required on win32 platforms only
1804 2192
1805 ev_select.c only when select backend is enabled (which is by default) 2193 ev_select.c only when select backend is enabled (which is enabled by default)
1806 ev_poll.c only when poll backend is enabled (disabled by default) 2194 ev_poll.c only when poll backend is enabled (disabled by default)
1807 ev_epoll.c only when the epoll backend is enabled (disabled by default) 2195 ev_epoll.c only when the epoll backend is enabled (disabled by default)
1808 ev_kqueue.c only when the kqueue backend is enabled (disabled by default) 2196 ev_kqueue.c only when the kqueue backend is enabled (disabled by default)
1809 ev_port.c only when the solaris port backend is enabled (disabled by default) 2197 ev_port.c only when the solaris port backend is enabled (disabled by default)
1810 2198
… …
1937 </dd> 2325 </dd>
1938 <dt>EV_USE_DEVPOLL</dt> 2326 <dt>EV_USE_DEVPOLL</dt>
1939 <dd> 2327 <dd>
1940 <p>reserved for future expansion, works like the USE symbols above.</p> 2328 <p>reserved for future expansion, works like the USE symbols above.</p>
1941 </dd> 2329 </dd>
2330 <dt>EV_USE_INOTIFY</dt>
2331 <dd>
2332 <p>If defined to be <code>1</code>, libev will compile in support for the Linux inotify
2333interface to speed up <code>ev_stat</code> watchers. Its actual availability will
2334be detected at runtime.</p>
2335 </dd>
1942 <dt>EV_H</dt> 2336 <dt>EV_H</dt>
1943 <dd> 2337 <dd>
1944 <p>The name of the <cite>ev.h</cite> header file used to include it. The default if 2338 <p>The name of the <cite>ev.h</cite> header file used to include it. The default if
1945undefined 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 2339undefined 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
1946can be used to virtually rename the <cite>ev.h</cite> header file in case of conflicts.</p> 2340can be used to virtually rename the <cite>ev.h</cite> header file in case of conflicts.</p>
… …
1969will have the <code>struct ev_loop *</code> as first argument, and you can create 2363will have the <code>struct ev_loop *</code> as first argument, and you can create
1970additional independent event loops. Otherwise there will be no support 2364additional independent event loops. Otherwise there will be no support
1971for multiple event loops and there is no first event loop pointer 2365for multiple event loops and there is no first event loop pointer
1972argument. Instead, all functions act on the single default loop.</p> 2366argument. Instead, all functions act on the single default loop.</p>
1973 </dd> 2367 </dd>
2368 <dt>EV_MINPRI</dt>
2369 <dt>EV_MAXPRI</dt>
2370 <dd>
2371 <p>The range of allowed priorities. <code>EV_MINPRI</code> must be smaller or equal to
2372<code>EV_MAXPRI</code>, but otherwise there are no non-obvious limitations. You can
2373provide for more priorities by overriding those symbols (usually defined
2374to be <code>-2</code> and <code>2</code>, respectively).</p>
2375 <p>When doing priority-based operations, libev usually has to linearly search
2376all the priorities, so having many of them (hundreds) uses a lot of space
2377and time, so using the defaults of five priorities (-2 .. +2) is usually
2378fine.</p>
2379 <p>If your embedding app does not need any priorities, defining these both to
2380<code>0</code> will save some memory and cpu.</p>
2381 </dd>
1974 <dt>EV_PERIODIC_ENABLE</dt> 2382 <dt>EV_PERIODIC_ENABLE</dt>
1975 <dd> 2383 <dd>
1976 <p>If undefined or defined to be <code>1</code>, then periodic timers are supported. If 2384 <p>If undefined or defined to be <code>1</code>, then periodic timers are supported. If
1977defined to be <code>0</code>, then they are not. Disabling them saves a few kB of 2385defined to be <code>0</code>, then they are not. Disabling them saves a few kB of
1978code.</p> 2386code.</p>
1979 </dd> 2387 </dd>
2388 <dt>EV_IDLE_ENABLE</dt>
2389 <dd>
2390 <p>If undefined or defined to be <code>1</code>, then idle watchers are supported. If
2391defined to be <code>0</code>, then they are not. Disabling them saves a few kB of
2392code.</p>
2393 </dd>
1980 <dt>EV_EMBED_ENABLE</dt> 2394 <dt>EV_EMBED_ENABLE</dt>
1981 <dd> 2395 <dd>
1982 <p>If undefined or defined to be <code>1</code>, then embed watchers are supported. If 2396 <p>If undefined or defined to be <code>1</code>, then embed watchers are supported. If
1983defined to be <code>0</code>, then they are not.</p> 2397defined to be <code>0</code>, then they are not.</p>
1984 </dd> 2398 </dd>
… …
2001 <dt>EV_PID_HASHSIZE</dt> 2415 <dt>EV_PID_HASHSIZE</dt>
2002 <dd> 2416 <dd>
2003 <p><code>ev_child</code> watchers use a small hash table to distribute workload by 2417 <p><code>ev_child</code> watchers use a small hash table to distribute workload by
2004pid. The default size is <code>16</code> (or <code>1</code> with <code>EV_MINIMAL</code>), usually more 2418pid. The default size is <code>16</code> (or <code>1</code> with <code>EV_MINIMAL</code>), usually more
2005than enough. If you need to manage thousands of children you might want to 2419than enough. If you need to manage thousands of children you might want to
2006increase this value.</p> 2420increase this value (<i>must</i> be a power of two).</p>
2421 </dd>
2422 <dt>EV_INOTIFY_HASHSIZE</dt>
2423 <dd>
2424 <p><code>ev_staz</code> watchers use a small hash table to distribute workload by
2425inotify watch id. The default size is <code>16</code> (or <code>1</code> with <code>EV_MINIMAL</code>),
2426usually more than enough. If you need to manage thousands of <code>ev_stat</code>
2427watchers you might want to increase this value (<i>must</i> be a power of
2428two).</p>
2007 </dd> 2429 </dd>
2008 <dt>EV_COMMON</dt> 2430 <dt>EV_COMMON</dt>
2009 <dd> 2431 <dd>
2010 <p>By default, all watchers have a <code>void *data</code> member. By redefining 2432 <p>By default, all watchers have a <code>void *data</code> member. By redefining
2011this macro to a something else you can include more and other types of 2433this macro to a something else you can include more and other types of
… …
2038the <cite>libev/</cite> subdirectory and includes them in the <cite>EV/EVAPI.h</cite> (public 2460the <cite>libev/</cite> subdirectory and includes them in the <cite>EV/EVAPI.h</cite> (public
2039interface) and <cite>EV.xs</cite> (implementation) files. Only the <cite>EV.xs</cite> file 2461interface) and <cite>EV.xs</cite> (implementation) files. Only the <cite>EV.xs</cite> file
2040will be compiled. It is pretty complex because it provides its own header 2462will be compiled. It is pretty complex because it provides its own header
2041file.</p> 2463file.</p>
2042 <p>The usage in rxvt-unicode is simpler. It has a <cite>ev_cpp.h</cite> header file 2464 <p>The usage in rxvt-unicode is simpler. It has a <cite>ev_cpp.h</cite> header file
2043that everybody includes and which overrides some autoconf choices:</p> 2465that everybody includes and which overrides some configure choices:</p>
2466<pre> #define EV_MINIMAL 1
2044<pre> #define EV_USE_POLL 0 2467 #define EV_USE_POLL 0
2045 #define EV_MULTIPLICITY 0 2468 #define EV_MULTIPLICITY 0
2046 #define EV_PERIODICS 0 2469 #define EV_PERIODIC_ENABLE 0
2470 #define EV_STAT_ENABLE 0
2471 #define EV_FORK_ENABLE 0
2047 #define EV_CONFIG_H &lt;config.h&gt; 2472 #define EV_CONFIG_H &lt;config.h&gt;
2473 #define EV_MINPRI 0
2474 #define EV_MAXPRI 0
2048 2475
2049 #include &quot;ev++.h&quot; 2476 #include &quot;ev++.h&quot;
2050 2477
2051</pre> 2478</pre>
2052 <p>And a <cite>ev_cpp.C</cite> implementation file that contains libev proper and is compiled:</p> 2479 <p>And a <cite>ev_cpp.C</cite> implementation file that contains libev proper and is compiled:</p>
… …
2057 2484
2058 2485
2059</pre> 2486</pre>
2060 2487
2061</div> 2488</div>
2062<h1 id="COMPLEXITIES">COMPLEXITIES</h1><p><a href="#TOP" class="toplink">Top</a></p> 2489<h1 id="COMPLEXITIES">COMPLEXITIES</h1>
2063<div id="COMPLEXITIES_CONTENT"> 2490<div id="COMPLEXITIES_CONTENT">
2064 <p>In this section the complexities of (many of) the algorithms used inside 2491 <p>In this section the complexities of (many of) the algorithms used inside
2065libev will be explained. For complexity discussions about backends see the 2492libev will be explained. For complexity discussions about backends see the
2066documentation for <code>ev_default_init</code>.</p> 2493documentation for <code>ev_default_init</code>.</p>
2494 <p>All of the following are about amortised time: If an array needs to be
2495extended, libev needs to realloc and move the whole array, but this
2496happens asymptotically never with higher number of elements, so O(1) might
2497mean it might do a lengthy realloc operation in rare cases, but on average
2498it is much faster and asymptotically approaches constant time.</p>
2067 <p> 2499 <p>
2068 <dl> 2500 <dl>
2069 <dt>Starting and stopping timer/periodic watchers: O(log skipped_other_timers)</dt> 2501 <dt>Starting and stopping timer/periodic watchers: O(log skipped_other_timers)</dt>
2502 <dd>
2503 <p>This means that, when you have a watcher that triggers in one hour and
2504there are 100 watchers that would trigger before that then inserting will
2505have to skip those 100 watchers.</p>
2506 </dd>
2070 <dt>Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)</dt> 2507 <dt>Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)</dt>
2508 <dd>
2509 <p>That means that for changing a timer costs less than removing/adding them
2510as only the relative motion in the event queue has to be paid for.</p>
2511 </dd>
2071 <dt>Starting io/check/prepare/idle/signal/child watchers: O(1)</dt> 2512 <dt>Starting io/check/prepare/idle/signal/child watchers: O(1)</dt>
2513 <dd>
2514 <p>These just add the watcher into an array or at the head of a list.
2072 <dt>Stopping check/prepare/idle watchers: O(1)</dt> 2515=item Stopping check/prepare/idle watchers: O(1)</p>
2516 </dd>
2073 <dt>Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % 16))</dt> 2517 <dt>Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))</dt>
2518 <dd>
2519 <p>These watchers are stored in lists then need to be walked to find the
2520correct watcher to remove. The lists are usually short (you don't usually
2521have many watchers waiting for the same fd or signal).</p>
2522 </dd>
2074 <dt>Finding the next timer per loop iteration: O(1)</dt> 2523 <dt>Finding the next timer per loop iteration: O(1)</dt>
2075 <dt>Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)</dt> 2524 <dt>Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)</dt>
2525 <dd>
2526 <p>A change means an I/O watcher gets started or stopped, which requires
2527libev to recalculate its status (and possibly tell the kernel).</p>
2528 </dd>
2076 <dt>Activating one watcher: O(1)</dt> 2529 <dt>Activating one watcher: O(1)</dt>
2530 <dt>Priority handling: O(number_of_priorities)</dt>
2531 <dd>
2532 <p>Priorities are implemented by allocating some space for each
2533priority. When doing priority-based operations, libev usually has to
2534linearly search all the priorities.</p>
2535 </dd>
2077 </dl> 2536 </dl>
2078 </p> 2537 </p>
2079 2538
2080 2539
2081 2540
2082 2541
2083 2542
2084</div> 2543</div>
2085<h1 id="AUTHOR">AUTHOR</h1><p><a href="#TOP" class="toplink">Top</a></p> 2544<h1 id="AUTHOR">AUTHOR</h1>
2086<div id="AUTHOR_CONTENT"> 2545<div id="AUTHOR_CONTENT">
2087 <p>Marc Lehmann &lt;libev@schmorp.de&gt;.</p> 2546 <p>Marc Lehmann &lt;libev@schmorp.de&gt;.</p>
2088 2547
2089</div> 2548</div>
2090</div></body> 2549</div></body>

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