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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="Mon Nov 26 11:20:35 2007" /> 9 <meta name="created" content="Fri Dec 7 17:49:47 2007" />
10 <meta name="generator" content="Pod::Xhtml 1.57" /> 10 <meta name="generator" content="Pod::Xhtml 1.57" />
11<link rel="stylesheet" href="http://res.tst.eu/pod.css"/></head> 11<link rel="stylesheet" href="http://res.tst.eu/pod.css"/></head>
12<body> 12<body>
13<div class="pod"> 13<div class="pod">
14<!-- INDEX START --> 14<!-- INDEX START -->
15<h3 id="TOP">Index</h3> 15<h3 id="TOP">Index</h3>
16 16
17<ul><li><a href="#NAME">NAME</a></li> 17<ul><li><a href="#NAME">NAME</a></li>
18<li><a href="#SYNOPSIS">SYNOPSIS</a></li> 18<li><a href="#SYNOPSIS">SYNOPSIS</a></li>
19<li><a href="#EXAMPLE_PROGRAM">EXAMPLE PROGRAM</a></li>
19<li><a href="#DESCRIPTION">DESCRIPTION</a></li> 20<li><a href="#DESCRIPTION">DESCRIPTION</a></li>
20<li><a href="#FEATURES">FEATURES</a></li> 21<li><a href="#FEATURES">FEATURES</a></li>
21<li><a href="#CONVENTIONS">CONVENTIONS</a></li> 22<li><a href="#CONVENTIONS">CONVENTIONS</a></li>
22<li><a href="#TIME_REPRESENTATION">TIME REPRESENTATION</a></li> 23<li><a href="#TIME_REPRESENTATION">TIME REPRESENTATION</a></li>
23<li><a href="#GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</a></li> 24<li><a href="#GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</a></li>
… …
31<ul><li><a href="#code_ev_io_code_is_this_file_descrip"><code>ev_io</code> - is this file descriptor readable or writable?</a></li> 32<ul><li><a href="#code_ev_io_code_is_this_file_descrip"><code>ev_io</code> - is this file descriptor readable or writable?</a></li>
32<li><a href="#code_ev_timer_code_relative_and_opti"><code>ev_timer</code> - relative and optionally repeating timeouts</a></li> 33<li><a href="#code_ev_timer_code_relative_and_opti"><code>ev_timer</code> - relative and optionally repeating timeouts</a></li>
33<li><a href="#code_ev_periodic_code_to_cron_or_not"><code>ev_periodic</code> - to cron or not to cron?</a></li> 34<li><a href="#code_ev_periodic_code_to_cron_or_not"><code>ev_periodic</code> - to cron or not to cron?</a></li>
34<li><a href="#code_ev_signal_code_signal_me_when_a"><code>ev_signal</code> - signal me when a signal gets signalled!</a></li> 35<li><a href="#code_ev_signal_code_signal_me_when_a"><code>ev_signal</code> - signal me when a signal gets signalled!</a></li>
35<li><a href="#code_ev_child_code_watch_out_for_pro"><code>ev_child</code> - watch out for process status changes</a></li> 36<li><a href="#code_ev_child_code_watch_out_for_pro"><code>ev_child</code> - watch out for process status changes</a></li>
37<li><a href="#code_ev_stat_code_did_the_file_attri"><code>ev_stat</code> - did the file attributes just change?</a></li>
36<li><a href="#code_ev_idle_code_when_you_ve_got_no"><code>ev_idle</code> - when you've got nothing better to do...</a></li> 38<li><a href="#code_ev_idle_code_when_you_ve_got_no"><code>ev_idle</code> - when you've got nothing better to do...</a></li>
37<li><a href="#code_ev_prepare_code_and_code_ev_che"><code>ev_prepare</code> and <code>ev_check</code> - customise your event loop!</a></li> 39<li><a href="#code_ev_prepare_code_and_code_ev_che"><code>ev_prepare</code> and <code>ev_check</code> - customise your event loop!</a></li>
38<li><a href="#code_ev_embed_code_when_one_backend_"><code>ev_embed</code> - when one backend isn't enough...</a></li> 40<li><a href="#code_ev_embed_code_when_one_backend_"><code>ev_embed</code> - when one backend isn't enough...</a></li>
41<li><a href="#code_ev_fork_code_the_audacity_to_re"><code>ev_fork</code> - the audacity to resume the event loop after a fork</a></li>
39</ul> 42</ul>
40</li> 43</li>
41<li><a href="#OTHER_FUNCTIONS">OTHER FUNCTIONS</a></li> 44<li><a href="#OTHER_FUNCTIONS">OTHER FUNCTIONS</a></li>
42<li><a href="#LIBEVENT_EMULATION">LIBEVENT EMULATION</a></li> 45<li><a href="#LIBEVENT_EMULATION">LIBEVENT EMULATION</a></li>
43<li><a href="#C_SUPPORT">C++ SUPPORT</a></li> 46<li><a href="#C_SUPPORT">C++ SUPPORT</a></li>
47<li><a href="#MACRO_MAGIC">MACRO MAGIC</a></li>
44<li><a href="#EMBEDDING">EMBEDDING</a> 48<li><a href="#EMBEDDING">EMBEDDING</a>
45<ul><li><a href="#FILESETS">FILESETS</a> 49<ul><li><a href="#FILESETS">FILESETS</a>
46<ul><li><a href="#CORE_EVENT_LOOP">CORE EVENT LOOP</a></li> 50<ul><li><a href="#CORE_EVENT_LOOP">CORE EVENT LOOP</a></li>
47<li><a href="#LIBEVENT_COMPATIBILITY_API">LIBEVENT COMPATIBILITY API</a></li> 51<li><a href="#LIBEVENT_COMPATIBILITY_API">LIBEVENT COMPATIBILITY API</a></li>
48<li><a href="#AUTOCONF_SUPPORT">AUTOCONF SUPPORT</a></li> 52<li><a href="#AUTOCONF_SUPPORT">AUTOCONF SUPPORT</a></li>
… …
56<li><a href="#AUTHOR">AUTHOR</a> 60<li><a href="#AUTHOR">AUTHOR</a>
57</li> 61</li>
58</ul><hr /> 62</ul><hr />
59<!-- INDEX END --> 63<!-- INDEX END -->
60 64
61<h1 id="NAME">NAME</h1><p><a href="#TOP" class="toplink">Top</a></p> 65<h1 id="NAME">NAME</h1>
62<div id="NAME_CONTENT"> 66<div id="NAME_CONTENT">
63<p>libev - a high performance full-featured event loop written in C</p> 67<p>libev - a high performance full-featured event loop written in C</p>
64 68
65</div> 69</div>
66<h1 id="SYNOPSIS">SYNOPSIS</h1><p><a href="#TOP" class="toplink">Top</a></p> 70<h1 id="SYNOPSIS">SYNOPSIS</h1>
67<div id="SYNOPSIS_CONTENT"> 71<div id="SYNOPSIS_CONTENT">
68<pre> #include &lt;ev.h&gt; 72<pre> #include &lt;ev.h&gt;
69 73
70</pre> 74</pre>
71 75
72</div> 76</div>
73<h1 id="DESCRIPTION">DESCRIPTION</h1><p><a href="#TOP" class="toplink">Top</a></p> 77<h1 id="EXAMPLE_PROGRAM">EXAMPLE PROGRAM</h1>
78<div id="EXAMPLE_PROGRAM_CONTENT">
79<pre> #include &lt;ev.h&gt;
80
81 ev_io stdin_watcher;
82 ev_timer timeout_watcher;
83
84 /* called when data readable on stdin */
85 static void
86 stdin_cb (EV_P_ struct ev_io *w, int revents)
87 {
88 /* puts (&quot;stdin ready&quot;); */
89 ev_io_stop (EV_A_ w); /* just a syntax example */
90 ev_unloop (EV_A_ EVUNLOOP_ALL); /* leave all loop calls */
91 }
92
93 static void
94 timeout_cb (EV_P_ struct ev_timer *w, int revents)
95 {
96 /* puts (&quot;timeout&quot;); */
97 ev_unloop (EV_A_ EVUNLOOP_ONE); /* leave one loop call */
98 }
99
100 int
101 main (void)
102 {
103 struct ev_loop *loop = ev_default_loop (0);
104
105 /* initialise an io watcher, then start it */
106 ev_io_init (&amp;stdin_watcher, stdin_cb, /*STDIN_FILENO*/ 0, EV_READ);
107 ev_io_start (loop, &amp;stdin_watcher);
108
109 /* simple non-repeating 5.5 second timeout */
110 ev_timer_init (&amp;timeout_watcher, timeout_cb, 5.5, 0.);
111 ev_timer_start (loop, &amp;timeout_watcher);
112
113 /* loop till timeout or data ready */
114 ev_loop (loop, 0);
115
116 return 0;
117 }
118
119</pre>
120
121</div>
122<h1 id="DESCRIPTION">DESCRIPTION</h1>
74<div id="DESCRIPTION_CONTENT"> 123<div id="DESCRIPTION_CONTENT">
75<p>Libev is an event loop: you register interest in certain events (such as a 124<p>Libev is an event loop: you register interest in certain events (such as a
76file descriptor being readable or a timeout occuring), and it will manage 125file descriptor being readable or a timeout occuring), and it will manage
77these event sources and provide your program with events.</p> 126these event sources and provide your program with events.</p>
78<p>To do this, it must take more or less complete control over your process 127<p>To do this, it must take more or less complete control over your process
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82watchers</i>, which are relatively small C structures you initialise with the 131watchers</i>, which are relatively small C structures you initialise with the
83details of the event, and then hand it over to libev by <i>starting</i> the 132details of the event, and then hand it over to libev by <i>starting</i> the
84watcher.</p> 133watcher.</p>
85 134
86</div> 135</div>
87<h1 id="FEATURES">FEATURES</h1><p><a href="#TOP" class="toplink">Top</a></p> 136<h1 id="FEATURES">FEATURES</h1>
88<div id="FEATURES_CONTENT"> 137<div id="FEATURES_CONTENT">
89<p>Libev supports select, poll, the linux-specific epoll and the bsd-specific 138<p>Libev supports <code>select</code>, <code>poll</code>, the Linux-specific <code>epoll</code>, the
90kqueue mechanisms for file descriptor events, relative timers, absolute 139BSD-specific <code>kqueue</code> and the Solaris-specific event port mechanisms
91timers with customised rescheduling, signal events, process status change 140for file descriptor events (<code>ev_io</code>), the Linux <code>inotify</code> interface
92events (related to SIGCHLD), and event watchers dealing with the event 141(for <code>ev_stat</code>), relative timers (<code>ev_timer</code>), absolute timers
93loop mechanism itself (idle, prepare and check watchers). It also is quite 142with customised rescheduling (<code>ev_periodic</code>), synchronous signals
143(<code>ev_signal</code>), process status change events (<code>ev_child</code>), and event
144watchers dealing with the event loop mechanism itself (<code>ev_idle</code>,
145<code>ev_embed</code>, <code>ev_prepare</code> and <code>ev_check</code> watchers) as well as
146file watchers (<code>ev_stat</code>) and even limited support for fork events
147(<code>ev_fork</code>).</p>
148<p>It also is quite fast (see this
94fast (see this <a href="http://libev.schmorp.de/bench.html">benchmark</a> comparing 149<a href="http://libev.schmorp.de/bench.html">benchmark</a> comparing it to libevent
95it to libevent for example).</p> 150for example).</p>
96 151
97</div> 152</div>
98<h1 id="CONVENTIONS">CONVENTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p> 153<h1 id="CONVENTIONS">CONVENTIONS</h1>
99<div id="CONVENTIONS_CONTENT"> 154<div id="CONVENTIONS_CONTENT">
100<p>Libev is very configurable. In this manual the default configuration 155<p>Libev is very configurable. In this manual the default configuration will
101will be described, which supports multiple event loops. For more info 156be described, which supports multiple event loops. For more info about
102about various configuration options please have a look at the file 157various configuration options please have a look at <strong>EMBED</strong> section in
103<cite>README.embed</cite> in the libev distribution. If libev was configured without 158this manual. If libev was configured without support for multiple event
104support for multiple event loops, then all functions taking an initial 159loops, then all functions taking an initial argument of name <code>loop</code>
105argument of name <code>loop</code> (which is always of type <code>struct ev_loop *</code>) 160(which is always of type <code>struct ev_loop *</code>) will not have this argument.</p>
106will not have this argument.</p>
107 161
108</div> 162</div>
109<h1 id="TIME_REPRESENTATION">TIME REPRESENTATION</h1><p><a href="#TOP" class="toplink">Top</a></p> 163<h1 id="TIME_REPRESENTATION">TIME REPRESENTATION</h1>
110<div id="TIME_REPRESENTATION_CONTENT"> 164<div id="TIME_REPRESENTATION_CONTENT">
111<p>Libev represents time as a single floating point number, representing the 165<p>Libev represents time as a single floating point number, representing the
112(fractional) number of seconds since the (POSIX) epoch (somewhere near 166(fractional) number of seconds since the (POSIX) epoch (somewhere near
113the beginning of 1970, details are complicated, don't ask). This type is 167the beginning of 1970, details are complicated, don't ask). This type is
114called <code>ev_tstamp</code>, which is what you should use too. It usually aliases 168called <code>ev_tstamp</code>, which is what you should use too. It usually aliases
115to the <code>double</code> type in C, and when you need to do any calculations on 169to the <code>double</code> type in C, and when you need to do any calculations on
116it, you should treat it as such.</p> 170it, you should treat it as such.</p>
117 171
118
119
120
121
122</div> 172</div>
123<h1 id="GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p> 173<h1 id="GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</h1>
124<div id="GLOBAL_FUNCTIONS_CONTENT"> 174<div id="GLOBAL_FUNCTIONS_CONTENT">
125<p>These functions can be called anytime, even before initialising the 175<p>These functions can be called anytime, even before initialising the
126library in any way.</p> 176library in any way.</p>
127<dl> 177<dl>
128 <dt>ev_tstamp ev_time ()</dt> 178 <dt>ev_tstamp ev_time ()</dt>
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141version of the library your program was compiled against.</p> 191version of the library your program was compiled against.</p>
142 <p>Usually, it's a good idea to terminate if the major versions mismatch, 192 <p>Usually, it's a good idea to terminate if the major versions mismatch,
143as this indicates an incompatible change. Minor versions are usually 193as this indicates an incompatible change. Minor versions are usually
144compatible to older versions, so a larger minor version alone is usually 194compatible to older versions, so a larger minor version alone is usually
145not a problem.</p> 195not a problem.</p>
146 <p>Example: make sure we haven't accidentally been linked against the wrong 196 <p>Example: Make sure we haven't accidentally been linked against the wrong
147version:</p> 197version.</p>
148<pre> assert ((&quot;libev version mismatch&quot;, 198<pre> assert ((&quot;libev version mismatch&quot;,
149 ev_version_major () == EV_VERSION_MAJOR 199 ev_version_major () == EV_VERSION_MAJOR
150 &amp;&amp; ev_version_minor () &gt;= EV_VERSION_MINOR)); 200 &amp;&amp; ev_version_minor () &gt;= EV_VERSION_MINOR));
151 201
152</pre> 202</pre>
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182recommended ones.</p> 232recommended ones.</p>
183 <p>See the description of <code>ev_embed</code> watchers for more info.</p> 233 <p>See the description of <code>ev_embed</code> watchers for more info.</p>
184 </dd> 234 </dd>
185 <dt>ev_set_allocator (void *(*cb)(void *ptr, long size))</dt> 235 <dt>ev_set_allocator (void *(*cb)(void *ptr, long size))</dt>
186 <dd> 236 <dd>
187 <p>Sets the allocation function to use (the prototype is similar to the 237 <p>Sets the allocation function to use (the prototype is similar - the
188realloc C function, the semantics are identical). It is used to allocate 238semantics is identical - to the realloc C function). It is used to
189and free memory (no surprises here). If it returns zero when memory 239allocate and free memory (no surprises here). If it returns zero when
190needs to be allocated, the library might abort or take some potentially 240memory needs to be allocated, the library might abort or take some
191destructive action. The default is your system realloc function.</p> 241potentially destructive action. The default is your system realloc
242function.</p>
192 <p>You could override this function in high-availability programs to, say, 243 <p>You could override this function in high-availability programs to, say,
193free some memory if it cannot allocate memory, to use a special allocator, 244free some memory if it cannot allocate memory, to use a special allocator,
194or even to sleep a while and retry until some memory is available.</p> 245or even to sleep a while and retry until some memory is available.</p>
195 <p>Example: replace the libev allocator with one that waits a bit and then 246 <p>Example: Replace the libev allocator with one that waits a bit and then
196retries: better than mine).</p> 247retries).</p>
197<pre> static void * 248<pre> static void *
198 persistent_realloc (void *ptr, long size) 249 persistent_realloc (void *ptr, size_t size)
199 { 250 {
200 for (;;) 251 for (;;)
201 { 252 {
202 void *newptr = realloc (ptr, size); 253 void *newptr = realloc (ptr, size);
203 254
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220indicating the system call or subsystem causing the problem. If this 271indicating the system call or subsystem causing the problem. If this
221callback is set, then libev will expect it to remedy the sitution, no 272callback is set, then libev will expect it to remedy the sitution, no
222matter what, when it returns. That is, libev will generally retry the 273matter what, when it returns. That is, libev will generally retry the
223requested operation, or, if the condition doesn't go away, do bad stuff 274requested operation, or, if the condition doesn't go away, do bad stuff
224(such as abort).</p> 275(such as abort).</p>
225 <p>Example: do the same thing as libev does internally:</p> 276 <p>Example: This is basically the same thing that libev does internally, too.</p>
226<pre> static void 277<pre> static void
227 fatal_error (const char *msg) 278 fatal_error (const char *msg)
228 { 279 {
229 perror (msg); 280 perror (msg);
230 abort (); 281 abort ();
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236</pre> 287</pre>
237 </dd> 288 </dd>
238</dl> 289</dl>
239 290
240</div> 291</div>
241<h1 id="FUNCTIONS_CONTROLLING_THE_EVENT_LOOP">FUNCTIONS CONTROLLING THE EVENT LOOP</h1><p><a href="#TOP" class="toplink">Top</a></p> 292<h1 id="FUNCTIONS_CONTROLLING_THE_EVENT_LOOP">FUNCTIONS CONTROLLING THE EVENT LOOP</h1>
242<div id="FUNCTIONS_CONTROLLING_THE_EVENT_LOOP-2"> 293<div id="FUNCTIONS_CONTROLLING_THE_EVENT_LOOP-2">
243<p>An event loop is described by a <code>struct ev_loop *</code>. The library knows two 294<p>An event loop is described by a <code>struct ev_loop *</code>. The library knows two
244types of such loops, the <i>default</i> loop, which supports signals and child 295types of such loops, the <i>default</i> loop, which supports signals and child
245events, and dynamically created loops which do not.</p> 296events, and dynamically created loops which do not.</p>
246<p>If you use threads, a common model is to run the default event loop 297<p>If you use threads, a common model is to run the default event loop
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274or setgid) then libev will <i>not</i> look at the environment variable 325or setgid) then libev will <i>not</i> look at the environment variable
275<code>LIBEV_FLAGS</code>. Otherwise (the default), this environment variable will 326<code>LIBEV_FLAGS</code>. Otherwise (the default), this environment variable will
276override the flags completely if it is found in the environment. This is 327override the flags completely if it is found in the environment. This is
277useful to try out specific backends to test their performance, or to work 328useful to try out specific backends to test their performance, or to work
278around bugs.</p> 329around bugs.</p>
330 </dd>
331 <dt><code>EVFLAG_FORKCHECK</code></dt>
332 <dd>
333 <p>Instead of calling <code>ev_default_fork</code> or <code>ev_loop_fork</code> manually after
334a fork, you can also make libev check for a fork in each iteration by
335enabling this flag.</p>
336 <p>This works by calling <code>getpid ()</code> on every iteration of the loop,
337and thus this might slow down your event loop if you do a lot of loop
338iterations and little real work, but is usually not noticeable (on my
339Linux system for example, <code>getpid</code> is actually a simple 5-insn sequence
340without a syscall and thus <i>very</i> fast, but my Linux system also has
341<code>pthread_atfork</code> which is even faster).</p>
342 <p>The big advantage of this flag is that you can forget about fork (and
343forget about forgetting to tell libev about forking) when you use this
344flag.</p>
345 <p>This flag setting cannot be overriden or specified in the <code>LIBEV_FLAGS</code>
346environment variable.</p>
279 </dd> 347 </dd>
280 <dt><code>EVBACKEND_SELECT</code> (value 1, portable select backend)</dt> 348 <dt><code>EVBACKEND_SELECT</code> (value 1, portable select backend)</dt>
281 <dd> 349 <dd>
282 <p>This is your standard select(2) backend. Not <i>completely</i> standard, as 350 <p>This is your standard select(2) backend. Not <i>completely</i> standard, as
283libev tries to roll its own fd_set with no limits on the number of fds, 351libev tries to roll its own fd_set with no limits on the number of fds,
… …
366 <dd> 434 <dd>
367 <p>Similar to <code>ev_default_loop</code>, but always creates a new event loop that is 435 <p>Similar to <code>ev_default_loop</code>, but always creates a new event loop that is
368always distinct from the default loop. Unlike the default loop, it cannot 436always distinct from the default loop. Unlike the default loop, it cannot
369handle signal and child watchers, and attempts to do so will be greeted by 437handle signal and child watchers, and attempts to do so will be greeted by
370undefined behaviour (or a failed assertion if assertions are enabled).</p> 438undefined behaviour (or a failed assertion if assertions are enabled).</p>
371 <p>Example: try to create a event loop that uses epoll and nothing else.</p> 439 <p>Example: Try to create a event loop that uses epoll and nothing else.</p>
372<pre> struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV); 440<pre> struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL | EVFLAG_NOENV);
373 if (!epoller) 441 if (!epoller)
374 fatal (&quot;no epoll found here, maybe it hides under your chair&quot;); 442 fatal (&quot;no epoll found here, maybe it hides under your chair&quot;);
375 443
376</pre> 444</pre>
… …
412 <dt>ev_loop_fork (loop)</dt> 480 <dt>ev_loop_fork (loop)</dt>
413 <dd> 481 <dd>
414 <p>Like <code>ev_default_fork</code>, but acts on an event loop created by 482 <p>Like <code>ev_default_fork</code>, but acts on an event loop created by
415<code>ev_loop_new</code>. Yes, you have to call this on every allocated event loop 483<code>ev_loop_new</code>. Yes, you have to call this on every allocated event loop
416after fork, and how you do this is entirely your own problem.</p> 484after fork, and how you do this is entirely your own problem.</p>
485 </dd>
486 <dt>unsigned int ev_loop_count (loop)</dt>
487 <dd>
488 <p>Returns the count of loop iterations for the loop, which is identical to
489the number of times libev did poll for new events. It starts at <code>0</code> and
490happily wraps around with enough iterations.</p>
491 <p>This value can sometimes be useful as a generation counter of sorts (it
492&quot;ticks&quot; the number of loop iterations), as it roughly corresponds with
493<code>ev_prepare</code> and <code>ev_check</code> calls.</p>
417 </dd> 494 </dd>
418 <dt>unsigned int ev_backend (loop)</dt> 495 <dt>unsigned int ev_backend (loop)</dt>
419 <dd> 496 <dd>
420 <p>Returns one of the <code>EVBACKEND_*</code> flags indicating the event backend in 497 <p>Returns one of the <code>EVBACKEND_*</code> flags indicating the event backend in
421use.</p> 498use.</p>
… …
469 be handled here by queueing them when their watcher gets executed. 546 be handled here by queueing them when their watcher gets executed.
470 - If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK 547 - If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK
471 were used, return, otherwise continue with step *. 548 were used, return, otherwise continue with step *.
472 549
473</pre> 550</pre>
474 <p>Example: queue some jobs and then loop until no events are outsanding 551 <p>Example: Queue some jobs and then loop until no events are outsanding
475anymore.</p> 552anymore.</p>
476<pre> ... queue jobs here, make sure they register event watchers as long 553<pre> ... queue jobs here, make sure they register event watchers as long
477 ... as they still have work to do (even an idle watcher will do..) 554 ... as they still have work to do (even an idle watcher will do..)
478 ev_loop (my_loop, 0); 555 ev_loop (my_loop, 0);
479 ... jobs done. yeah! 556 ... jobs done. yeah!
… …
498example, libev itself uses this for its internal signal pipe: It is not 575example, libev itself uses this for its internal signal pipe: It is not
499visible to the libev user and should not keep <code>ev_loop</code> from exiting if 576visible to the libev user and should not keep <code>ev_loop</code> from exiting if
500no event watchers registered by it are active. It is also an excellent 577no event watchers registered by it are active. It is also an excellent
501way to do this for generic recurring timers or from within third-party 578way to do this for generic recurring timers or from within third-party
502libraries. Just remember to <i>unref after start</i> and <i>ref before stop</i>.</p> 579libraries. Just remember to <i>unref after start</i> and <i>ref before stop</i>.</p>
503 <p>Example: create a signal watcher, but keep it from keeping <code>ev_loop</code> 580 <p>Example: Create a signal watcher, but keep it from keeping <code>ev_loop</code>
504running when nothing else is active.</p> 581running when nothing else is active.</p>
505<pre> struct dv_signal exitsig; 582<pre> struct ev_signal exitsig;
506 ev_signal_init (&amp;exitsig, sig_cb, SIGINT); 583 ev_signal_init (&amp;exitsig, sig_cb, SIGINT);
507 ev_signal_start (myloop, &amp;exitsig); 584 ev_signal_start (loop, &amp;exitsig);
508 evf_unref (myloop); 585 evf_unref (loop);
509 586
510</pre> 587</pre>
511 <p>Example: for some weird reason, unregister the above signal handler again.</p> 588 <p>Example: For some weird reason, unregister the above signal handler again.</p>
512<pre> ev_ref (myloop); 589<pre> ev_ref (loop);
513 ev_signal_stop (myloop, &amp;exitsig); 590 ev_signal_stop (loop, &amp;exitsig);
514 591
515</pre> 592</pre>
516 </dd> 593 </dd>
517</dl> 594</dl>
518 595
519 596
520 597
521 598
522 599
523</div> 600</div>
524<h1 id="ANATOMY_OF_A_WATCHER">ANATOMY OF A WATCHER</h1><p><a href="#TOP" class="toplink">Top</a></p> 601<h1 id="ANATOMY_OF_A_WATCHER">ANATOMY OF A WATCHER</h1>
525<div id="ANATOMY_OF_A_WATCHER_CONTENT"> 602<div id="ANATOMY_OF_A_WATCHER_CONTENT">
526<p>A watcher is a structure that you create and register to record your 603<p>A watcher is a structure that you create and register to record your
527interest in some event. For instance, if you want to wait for STDIN to 604interest in some event. For instance, if you want to wait for STDIN to
528become readable, you would create an <code>ev_io</code> watcher for that:</p> 605become readable, you would create an <code>ev_io</code> watcher for that:</p>
529<pre> static void my_cb (struct ev_loop *loop, struct ev_io *w, int revents) 606<pre> static void my_cb (struct ev_loop *loop, struct ev_io *w, int revents)
… …
586 </dd> 663 </dd>
587 <dt><code>EV_CHILD</code></dt> 664 <dt><code>EV_CHILD</code></dt>
588 <dd> 665 <dd>
589 <p>The pid specified in the <code>ev_child</code> watcher has received a status change.</p> 666 <p>The pid specified in the <code>ev_child</code> watcher has received a status change.</p>
590 </dd> 667 </dd>
668 <dt><code>EV_STAT</code></dt>
669 <dd>
670 <p>The path specified in the <code>ev_stat</code> watcher changed its attributes somehow.</p>
671 </dd>
591 <dt><code>EV_IDLE</code></dt> 672 <dt><code>EV_IDLE</code></dt>
592 <dd> 673 <dd>
593 <p>The <code>ev_idle</code> watcher has determined that you have nothing better to do.</p> 674 <p>The <code>ev_idle</code> watcher has determined that you have nothing better to do.</p>
594 </dd> 675 </dd>
595 <dt><code>EV_PREPARE</code></dt> 676 <dt><code>EV_PREPARE</code></dt>
… …
600<code>ev_loop</code> has gathered them, but before it invokes any callbacks for any 681<code>ev_loop</code> has gathered them, but before it invokes any callbacks for any
601received events. Callbacks of both watcher types can start and stop as 682received events. Callbacks of both watcher types can start and stop as
602many watchers as they want, and all of them will be taken into account 683many watchers as they want, and all of them will be taken into account
603(for example, a <code>ev_prepare</code> watcher might start an idle watcher to keep 684(for example, a <code>ev_prepare</code> watcher might start an idle watcher to keep
604<code>ev_loop</code> from blocking).</p> 685<code>ev_loop</code> from blocking).</p>
686 </dd>
687 <dt><code>EV_EMBED</code></dt>
688 <dd>
689 <p>The embedded event loop specified in the <code>ev_embed</code> watcher needs attention.</p>
690 </dd>
691 <dt><code>EV_FORK</code></dt>
692 <dd>
693 <p>The event loop has been resumed in the child process after fork (see
694<code>ev_fork</code>).</p>
605 </dd> 695 </dd>
606 <dt><code>EV_ERROR</code></dt> 696 <dt><code>EV_ERROR</code></dt>
607 <dd> 697 <dd>
608 <p>An unspecified error has occured, the watcher has been stopped. This might 698 <p>An unspecified error has occured, the watcher has been stopped. This might
609happen because the watcher could not be properly started because libev 699happen because the watcher could not be properly started because libev
… …
679events but its callback has not yet been invoked). As long as a watcher 769events but its callback has not yet been invoked). As long as a watcher
680is pending (but not active) you must not call an init function on it (but 770is pending (but not active) you must not call an init function on it (but
681<code>ev_TYPE_set</code> is safe) and you must make sure the watcher is available to 771<code>ev_TYPE_set</code> is safe) and you must make sure the watcher is available to
682libev (e.g. you cnanot <code>free ()</code> it).</p> 772libev (e.g. you cnanot <code>free ()</code> it).</p>
683 </dd> 773 </dd>
684 <dt>callback = ev_cb (ev_TYPE *watcher)</dt> 774 <dt>callback ev_cb (ev_TYPE *watcher)</dt>
685 <dd> 775 <dd>
686 <p>Returns the callback currently set on the watcher.</p> 776 <p>Returns the callback currently set on the watcher.</p>
687 </dd> 777 </dd>
688 <dt>ev_cb_set (ev_TYPE *watcher, callback)</dt> 778 <dt>ev_cb_set (ev_TYPE *watcher, callback)</dt>
689 <dd> 779 <dd>
690 <p>Change the callback. You can change the callback at virtually any time 780 <p>Change the callback. You can change the callback at virtually any time
691(modulo threads).</p> 781(modulo threads).</p>
782 </dd>
783 <dt>ev_set_priority (ev_TYPE *watcher, priority)</dt>
784 <dt>int ev_priority (ev_TYPE *watcher)</dt>
785 <dd>
786 <p>Set and query the priority of the watcher. The priority is a small
787integer between <code>EV_MAXPRI</code> (default: <code>2</code>) and <code>EV_MINPRI</code>
788(default: <code>-2</code>). Pending watchers with higher priority will be invoked
789before watchers with lower priority, but priority will not keep watchers
790from being executed (except for <code>ev_idle</code> watchers).</p>
791 <p>This means that priorities are <i>only</i> used for ordering callback
792invocation after new events have been received. This is useful, for
793example, to reduce latency after idling, or more often, to bind two
794watchers on the same event and make sure one is called first.</p>
795 <p>If you need to suppress invocation when higher priority events are pending
796you need to look at <code>ev_idle</code> watchers, which provide this functionality.</p>
797 <p>The default priority used by watchers when no priority has been set is
798always <code>0</code>, which is supposed to not be too high and not be too low :).</p>
799 <p>Setting a priority outside the range of <code>EV_MINPRI</code> to <code>EV_MAXPRI</code> is
800fine, as long as you do not mind that the priority value you query might
801or might not have been adjusted to be within valid range.</p>
692 </dd> 802 </dd>
693</dl> 803</dl>
694 804
695 805
696 806
… …
721 struct my_io *w = (struct my_io *)w_; 831 struct my_io *w = (struct my_io *)w_;
722 ... 832 ...
723 } 833 }
724 834
725</pre> 835</pre>
726<p>More interesting and less C-conformant ways of catsing your callback type 836<p>More interesting and less C-conformant ways of casting your callback type
727have been omitted....</p> 837instead have been omitted.</p>
838<p>Another common scenario is having some data structure with multiple
839watchers:</p>
840<pre> struct my_biggy
841 {
842 int some_data;
843 ev_timer t1;
844 ev_timer t2;
845 }
728 846
847</pre>
848<p>In this case getting the pointer to <code>my_biggy</code> is a bit more complicated,
849you need to use <code>offsetof</code>:</p>
850<pre> #include &lt;stddef.h&gt;
729 851
852 static void
853 t1_cb (EV_P_ struct ev_timer *w, int revents)
854 {
855 struct my_biggy big = (struct my_biggy *
856 (((char *)w) - offsetof (struct my_biggy, t1));
857 }
730 858
859 static void
860 t2_cb (EV_P_ struct ev_timer *w, int revents)
861 {
862 struct my_biggy big = (struct my_biggy *
863 (((char *)w) - offsetof (struct my_biggy, t2));
864 }
731 865
732 866
867
868
869</pre>
870
733</div> 871</div>
734<h1 id="WATCHER_TYPES">WATCHER TYPES</h1><p><a href="#TOP" class="toplink">Top</a></p> 872<h1 id="WATCHER_TYPES">WATCHER TYPES</h1>
735<div id="WATCHER_TYPES_CONTENT"> 873<div id="WATCHER_TYPES_CONTENT">
736<p>This section describes each watcher in detail, but will not repeat 874<p>This section describes each watcher in detail, but will not repeat
737information given in the last section.</p> 875information given in the last section. Any initialisation/set macros,
876functions and members specific to the watcher type are explained.</p>
877<p>Members are additionally marked with either <i>[read-only]</i>, meaning that,
878while the watcher is active, you can look at the member and expect some
879sensible content, but you must not modify it (you can modify it while the
880watcher is stopped to your hearts content), or <i>[read-write]</i>, which
881means you can expect it to have some sensible content while the watcher
882is active, but you can also modify it. Modifying it may not do something
883sensible or take immediate effect (or do anything at all), but libev will
884not crash or malfunction in any way.</p>
738 885
739 886
740 887
741 888
742 889
… …
781 <dd> 928 <dd>
782 <p>Configures an <code>ev_io</code> watcher. The <code>fd</code> is the file descriptor to 929 <p>Configures an <code>ev_io</code> watcher. The <code>fd</code> is the file descriptor to
783rceeive events for and events is either <code>EV_READ</code>, <code>EV_WRITE</code> or 930rceeive events for and events is either <code>EV_READ</code>, <code>EV_WRITE</code> or
784<code>EV_READ | EV_WRITE</code> to receive the given events.</p> 931<code>EV_READ | EV_WRITE</code> to receive the given events.</p>
785 </dd> 932 </dd>
933 <dt>int fd [read-only]</dt>
934 <dd>
935 <p>The file descriptor being watched.</p>
936 </dd>
937 <dt>int events [read-only]</dt>
938 <dd>
939 <p>The events being watched.</p>
940 </dd>
786</dl> 941</dl>
787<p>Example: call <code>stdin_readable_cb</code> when STDIN_FILENO has become, well 942<p>Example: Call <code>stdin_readable_cb</code> when STDIN_FILENO has become, well
788readable, but only once. Since it is likely line-buffered, you could 943readable, but only once. Since it is likely line-buffered, you could
789attempt to read a whole line in the callback:</p> 944attempt to read a whole line in the callback.</p>
790<pre> static void 945<pre> static void
791 stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents) 946 stdin_readable_cb (struct ev_loop *loop, struct ev_io *w, int revents)
792 { 947 {
793 ev_io_stop (loop, w); 948 ev_io_stop (loop, w);
794 .. read from stdin here (or from w-&gt;fd) and haqndle any I/O errors 949 .. read from stdin here (or from w-&gt;fd) and haqndle any I/O errors
… …
843 </dd> 998 </dd>
844 <dt>ev_timer_again (loop)</dt> 999 <dt>ev_timer_again (loop)</dt>
845 <dd> 1000 <dd>
846 <p>This will act as if the timer timed out and restart it again if it is 1001 <p>This will act as if the timer timed out and restart it again if it is
847repeating. The exact semantics are:</p> 1002repeating. The exact semantics are:</p>
1003 <p>If the timer is pending, its pending status is cleared.</p>
848 <p>If the timer is started but nonrepeating, stop it.</p> 1004 <p>If the timer is started but nonrepeating, stop it (as if it timed out).</p>
849 <p>If the timer is repeating, either start it if necessary (with the repeat 1005 <p>If the timer is repeating, either start it if necessary (with the
850value), or reset the running timer to the repeat value.</p> 1006<code>repeat</code> value), or reset the running timer to the <code>repeat</code> value.</p>
851 <p>This sounds a bit complicated, but here is a useful and typical 1007 <p>This sounds a bit complicated, but here is a useful and typical
852example: Imagine you have a tcp connection and you want a so-called idle 1008example: Imagine you have a tcp connection and you want a so-called idle
853timeout, that is, you want to be called when there have been, say, 60 1009timeout, that is, you want to be called when there have been, say, 60
854seconds of inactivity on the socket. The easiest way to do this is to 1010seconds of inactivity on the socket. The easiest way to do this is to
855configure an <code>ev_timer</code> with after=repeat=60 and calling ev_timer_again each 1011configure an <code>ev_timer</code> with a <code>repeat</code> value of <code>60</code> and then call
856time you successfully read or write some data. If you go into an idle 1012<code>ev_timer_again</code> each time you successfully read or write some data. If
857state where you do not expect data to travel on the socket, you can stop 1013you go into an idle state where you do not expect data to travel on the
1014socket, you can <code>ev_timer_stop</code> the timer, and <code>ev_timer_again</code> will
858the timer, and again will automatically restart it if need be.</p> 1015automatically restart it if need be.</p>
1016 <p>That means you can ignore the <code>after</code> value and <code>ev_timer_start</code>
1017altogether and only ever use the <code>repeat</code> value and <code>ev_timer_again</code>:</p>
1018<pre> ev_timer_init (timer, callback, 0., 5.);
1019 ev_timer_again (loop, timer);
1020 ...
1021 timer-&gt;again = 17.;
1022 ev_timer_again (loop, timer);
1023 ...
1024 timer-&gt;again = 10.;
1025 ev_timer_again (loop, timer);
1026
1027</pre>
1028 <p>This is more slightly efficient then stopping/starting the timer each time
1029you want to modify its timeout value.</p>
1030 </dd>
1031 <dt>ev_tstamp repeat [read-write]</dt>
1032 <dd>
1033 <p>The current <code>repeat</code> value. Will be used each time the watcher times out
1034or <code>ev_timer_again</code> is called and determines the next timeout (if any),
1035which is also when any modifications are taken into account.</p>
859 </dd> 1036 </dd>
860</dl> 1037</dl>
861<p>Example: create a timer that fires after 60 seconds.</p> 1038<p>Example: Create a timer that fires after 60 seconds.</p>
862<pre> static void 1039<pre> static void
863 one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents) 1040 one_minute_cb (struct ev_loop *loop, struct ev_timer *w, int revents)
864 { 1041 {
865 .. one minute over, w is actually stopped right here 1042 .. one minute over, w is actually stopped right here
866 } 1043 }
… …
868 struct ev_timer mytimer; 1045 struct ev_timer mytimer;
869 ev_timer_init (&amp;mytimer, one_minute_cb, 60., 0.); 1046 ev_timer_init (&amp;mytimer, one_minute_cb, 60., 0.);
870 ev_timer_start (loop, &amp;mytimer); 1047 ev_timer_start (loop, &amp;mytimer);
871 1048
872</pre> 1049</pre>
873<p>Example: create a timeout timer that times out after 10 seconds of 1050<p>Example: Create a timeout timer that times out after 10 seconds of
874inactivity.</p> 1051inactivity.</p>
875<pre> static void 1052<pre> static void
876 timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents) 1053 timeout_cb (struct ev_loop *loop, struct ev_timer *w, int revents)
877 { 1054 {
878 .. ten seconds without any activity 1055 .. ten seconds without any activity
… …
981 <p>Simply stops and restarts the periodic watcher again. This is only useful 1158 <p>Simply stops and restarts the periodic watcher again. This is only useful
982when you changed some parameters or the reschedule callback would return 1159when you changed some parameters or the reschedule callback would return
983a different time than the last time it was called (e.g. in a crond like 1160a different time than the last time it was called (e.g. in a crond like
984program when the crontabs have changed).</p> 1161program when the crontabs have changed).</p>
985 </dd> 1162 </dd>
1163 <dt>ev_tstamp interval [read-write]</dt>
1164 <dd>
1165 <p>The current interval value. Can be modified any time, but changes only
1166take effect when the periodic timer fires or <code>ev_periodic_again</code> is being
1167called.</p>
1168 </dd>
1169 <dt>ev_tstamp (*reschedule_cb)(struct ev_periodic *w, ev_tstamp now) [read-write]</dt>
1170 <dd>
1171 <p>The current reschedule callback, or <code>0</code>, if this functionality is
1172switched off. Can be changed any time, but changes only take effect when
1173the periodic timer fires or <code>ev_periodic_again</code> is being called.</p>
1174 </dd>
986</dl> 1175</dl>
987<p>Example: call a callback every hour, or, more precisely, whenever the 1176<p>Example: Call a callback every hour, or, more precisely, whenever the
988system clock is divisible by 3600. The callback invocation times have 1177system clock is divisible by 3600. The callback invocation times have
989potentially a lot of jittering, but good long-term stability.</p> 1178potentially a lot of jittering, but good long-term stability.</p>
990<pre> static void 1179<pre> static void
991 clock_cb (struct ev_loop *loop, struct ev_io *w, int revents) 1180 clock_cb (struct ev_loop *loop, struct ev_io *w, int revents)
992 { 1181 {
… …
996 struct ev_periodic hourly_tick; 1185 struct ev_periodic hourly_tick;
997 ev_periodic_init (&amp;hourly_tick, clock_cb, 0., 3600., 0); 1186 ev_periodic_init (&amp;hourly_tick, clock_cb, 0., 3600., 0);
998 ev_periodic_start (loop, &amp;hourly_tick); 1187 ev_periodic_start (loop, &amp;hourly_tick);
999 1188
1000</pre> 1189</pre>
1001<p>Example: the same as above, but use a reschedule callback to do it:</p> 1190<p>Example: The same as above, but use a reschedule callback to do it:</p>
1002<pre> #include &lt;math.h&gt; 1191<pre> #include &lt;math.h&gt;
1003 1192
1004 static ev_tstamp 1193 static ev_tstamp
1005 my_scheduler_cb (struct ev_periodic *w, ev_tstamp now) 1194 my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)
1006 { 1195 {
… …
1008 } 1197 }
1009 1198
1010 ev_periodic_init (&amp;hourly_tick, clock_cb, 0., 0., my_scheduler_cb); 1199 ev_periodic_init (&amp;hourly_tick, clock_cb, 0., 0., my_scheduler_cb);
1011 1200
1012</pre> 1201</pre>
1013<p>Example: call a callback every hour, starting now:</p> 1202<p>Example: Call a callback every hour, starting now:</p>
1014<pre> struct ev_periodic hourly_tick; 1203<pre> struct ev_periodic hourly_tick;
1015 ev_periodic_init (&amp;hourly_tick, clock_cb, 1204 ev_periodic_init (&amp;hourly_tick, clock_cb,
1016 fmod (ev_now (loop), 3600.), 3600., 0); 1205 fmod (ev_now (loop), 3600.), 3600., 0);
1017 ev_periodic_start (loop, &amp;hourly_tick); 1206 ev_periodic_start (loop, &amp;hourly_tick);
1018 1207
… …
1039 <dt>ev_signal_set (ev_signal *, int signum)</dt> 1228 <dt>ev_signal_set (ev_signal *, int signum)</dt>
1040 <dd> 1229 <dd>
1041 <p>Configures the watcher to trigger on the given signal number (usually one 1230 <p>Configures the watcher to trigger on the given signal number (usually one
1042of the <code>SIGxxx</code> constants).</p> 1231of the <code>SIGxxx</code> constants).</p>
1043 </dd> 1232 </dd>
1233 <dt>int signum [read-only]</dt>
1234 <dd>
1235 <p>The signal the watcher watches out for.</p>
1236 </dd>
1044</dl> 1237</dl>
1045 1238
1046 1239
1047 1240
1048 1241
… …
1061at the <code>rstatus</code> member of the <code>ev_child</code> watcher structure to see 1254at the <code>rstatus</code> member of the <code>ev_child</code> watcher structure to see
1062the status word (use the macros from <code>sys/wait.h</code> and see your systems 1255the status word (use the macros from <code>sys/wait.h</code> and see your systems
1063<code>waitpid</code> documentation). The <code>rpid</code> member contains the pid of the 1256<code>waitpid</code> documentation). The <code>rpid</code> member contains the pid of the
1064process causing the status change.</p> 1257process causing the status change.</p>
1065 </dd> 1258 </dd>
1259 <dt>int pid [read-only]</dt>
1260 <dd>
1261 <p>The process id this watcher watches out for, or <code>0</code>, meaning any process id.</p>
1262 </dd>
1263 <dt>int rpid [read-write]</dt>
1264 <dd>
1265 <p>The process id that detected a status change.</p>
1266 </dd>
1267 <dt>int rstatus [read-write]</dt>
1268 <dd>
1269 <p>The process exit/trace status caused by <code>rpid</code> (see your systems
1270<code>waitpid</code> and <code>sys/wait.h</code> documentation for details).</p>
1271 </dd>
1066</dl> 1272</dl>
1067<p>Example: try to exit cleanly on SIGINT and SIGTERM.</p> 1273<p>Example: Try to exit cleanly on SIGINT and SIGTERM.</p>
1068<pre> static void 1274<pre> static void
1069 sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents) 1275 sigint_cb (struct ev_loop *loop, struct ev_signal *w, int revents)
1070 { 1276 {
1071 ev_unloop (loop, EVUNLOOP_ALL); 1277 ev_unloop (loop, EVUNLOOP_ALL);
1072 } 1278 }
… …
1079 1285
1080 1286
1081</pre> 1287</pre>
1082 1288
1083</div> 1289</div>
1290<h2 id="code_ev_stat_code_did_the_file_attri"><code>ev_stat</code> - did the file attributes just change?</h2>
1291<div id="code_ev_stat_code_did_the_file_attri-2">
1292<p>This watches a filesystem path for attribute changes. That is, it calls
1293<code>stat</code> regularly (or when the OS says it changed) and sees if it changed
1294compared to the last time, invoking the callback if it did.</p>
1295<p>The path does not need to exist: changing from &quot;path exists&quot; to &quot;path does
1296not exist&quot; is a status change like any other. The condition &quot;path does
1297not exist&quot; is signified by the <code>st_nlink</code> field being zero (which is
1298otherwise always forced to be at least one) and all the other fields of
1299the stat buffer having unspecified contents.</p>
1300<p>The path <i>should</i> be absolute and <i>must not</i> end in a slash. If it is
1301relative and your working directory changes, the behaviour is undefined.</p>
1302<p>Since there is no standard to do this, the portable implementation simply
1303calls <code>stat (2)</code> regularly on the path to see if it changed somehow. You
1304can specify a recommended polling interval for this case. If you specify
1305a polling interval of <code>0</code> (highly recommended!) then a <i>suitable,
1306unspecified default</i> value will be used (which you can expect to be around
1307five seconds, although this might change dynamically). Libev will also
1308impose a minimum interval which is currently around <code>0.1</code>, but thats
1309usually overkill.</p>
1310<p>This watcher type is not meant for massive numbers of stat watchers,
1311as even with OS-supported change notifications, this can be
1312resource-intensive.</p>
1313<p>At the time of this writing, only the Linux inotify interface is
1314implemented (implementing kqueue support is left as an exercise for the
1315reader). Inotify will be used to give hints only and should not change the
1316semantics of <code>ev_stat</code> watchers, which means that libev sometimes needs
1317to fall back to regular polling again even with inotify, but changes are
1318usually detected immediately, and if the file exists there will be no
1319polling.</p>
1320<dl>
1321 <dt>ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)</dt>
1322 <dt>ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)</dt>
1323 <dd>
1324 <p>Configures the watcher to wait for status changes of the given
1325<code>path</code>. The <code>interval</code> is a hint on how quickly a change is expected to
1326be detected and should normally be specified as <code>0</code> to let libev choose
1327a suitable value. The memory pointed to by <code>path</code> must point to the same
1328path for as long as the watcher is active.</p>
1329 <p>The callback will be receive <code>EV_STAT</code> when a change was detected,
1330relative to the attributes at the time the watcher was started (or the
1331last change was detected).</p>
1332 </dd>
1333 <dt>ev_stat_stat (ev_stat *)</dt>
1334 <dd>
1335 <p>Updates the stat buffer immediately with new values. If you change the
1336watched path in your callback, you could call this fucntion to avoid
1337detecting this change (while introducing a race condition). Can also be
1338useful simply to find out the new values.</p>
1339 </dd>
1340 <dt>ev_statdata attr [read-only]</dt>
1341 <dd>
1342 <p>The most-recently detected attributes of the file. Although the type is of
1343<code>ev_statdata</code>, this is usually the (or one of the) <code>struct stat</code> types
1344suitable for your system. If the <code>st_nlink</code> member is <code>0</code>, then there
1345was some error while <code>stat</code>ing the file.</p>
1346 </dd>
1347 <dt>ev_statdata prev [read-only]</dt>
1348 <dd>
1349 <p>The previous attributes of the file. The callback gets invoked whenever
1350<code>prev</code> != <code>attr</code>.</p>
1351 </dd>
1352 <dt>ev_tstamp interval [read-only]</dt>
1353 <dd>
1354 <p>The specified interval.</p>
1355 </dd>
1356 <dt>const char *path [read-only]</dt>
1357 <dd>
1358 <p>The filesystem path that is being watched.</p>
1359 </dd>
1360</dl>
1361<p>Example: Watch <code>/etc/passwd</code> for attribute changes.</p>
1362<pre> static void
1363 passwd_cb (struct ev_loop *loop, ev_stat *w, int revents)
1364 {
1365 /* /etc/passwd changed in some way */
1366 if (w-&gt;attr.st_nlink)
1367 {
1368 printf (&quot;passwd current size %ld\n&quot;, (long)w-&gt;attr.st_size);
1369 printf (&quot;passwd current atime %ld\n&quot;, (long)w-&gt;attr.st_mtime);
1370 printf (&quot;passwd current mtime %ld\n&quot;, (long)w-&gt;attr.st_mtime);
1371 }
1372 else
1373 /* you shalt not abuse printf for puts */
1374 puts (&quot;wow, /etc/passwd is not there, expect problems. &quot;
1375 &quot;if this is windows, they already arrived\n&quot;);
1376 }
1377
1378 ...
1379 ev_stat passwd;
1380
1381 ev_stat_init (&amp;passwd, passwd_cb, &quot;/etc/passwd&quot;);
1382 ev_stat_start (loop, &amp;passwd);
1383
1384
1385
1386
1387</pre>
1388
1389</div>
1084<h2 id="code_ev_idle_code_when_you_ve_got_no"><code>ev_idle</code> - when you've got nothing better to do...</h2> 1390<h2 id="code_ev_idle_code_when_you_ve_got_no"><code>ev_idle</code> - when you've got nothing better to do...</h2>
1085<div id="code_ev_idle_code_when_you_ve_got_no-2"> 1391<div id="code_ev_idle_code_when_you_ve_got_no-2">
1086<p>Idle watchers trigger events when there are no other events are pending 1392<p>Idle watchers trigger events when no other events of the same or higher
1087(prepare, check and other idle watchers do not count). That is, as long 1393priority are pending (prepare, check and other idle watchers do not
1088as your process is busy handling sockets or timeouts (or even signals, 1394count).</p>
1089imagine) it will not be triggered. But when your process is idle all idle 1395<p>That is, as long as your process is busy handling sockets or timeouts
1090watchers are being called again and again, once per event loop iteration - 1396(or even signals, imagine) of the same or higher priority it will not be
1397triggered. But when your process is idle (or only lower-priority watchers
1398are pending), the idle watchers are being called once per event loop
1091until stopped, that is, or your process receives more events and becomes 1399iteration - until stopped, that is, or your process receives more events
1092busy.</p> 1400and becomes busy again with higher priority stuff.</p>
1093<p>The most noteworthy effect is that as long as any idle watchers are 1401<p>The most noteworthy effect is that as long as any idle watchers are
1094active, the process will not block when waiting for new events.</p> 1402active, the process will not block when waiting for new events.</p>
1095<p>Apart from keeping your process non-blocking (which is a useful 1403<p>Apart from keeping your process non-blocking (which is a useful
1096effect on its own sometimes), idle watchers are a good place to do 1404effect on its own sometimes), idle watchers are a good place to do
1097&quot;pseudo-background processing&quot;, or delay processing stuff to after the 1405&quot;pseudo-background processing&quot;, or delay processing stuff to after the
… …
1102 <p>Initialises and configures the idle watcher - it has no parameters of any 1410 <p>Initialises and configures the idle watcher - it has no parameters of any
1103kind. There is a <code>ev_idle_set</code> macro, but using it is utterly pointless, 1411kind. There is a <code>ev_idle_set</code> macro, but using it is utterly pointless,
1104believe me.</p> 1412believe me.</p>
1105 </dd> 1413 </dd>
1106</dl> 1414</dl>
1107<p>Example: dynamically allocate an <code>ev_idle</code>, start it, and in the 1415<p>Example: Dynamically allocate an <code>ev_idle</code> watcher, start it, and in the
1108callback, free it. Alos, use no error checking, as usual.</p> 1416callback, free it. Also, use no error checking, as usual.</p>
1109<pre> static void 1417<pre> static void
1110 idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents) 1418 idle_cb (struct ev_loop *loop, struct ev_idle *w, int revents)
1111 { 1419 {
1112 free (w); 1420 free (w);
1113 // now do something you wanted to do when the program has 1421 // now do something you wanted to do when the program has
… …
1187 1495
1188 // create io watchers for each fd and a timer before blocking 1496 // create io watchers for each fd and a timer before blocking
1189 static void 1497 static void
1190 adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) 1498 adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents)
1191 { 1499 {
1192 int timeout = 3600000;truct pollfd fds [nfd]; 1500 int timeout = 3600000;
1501 struct pollfd fds [nfd];
1193 // actual code will need to loop here and realloc etc. 1502 // actual code will need to loop here and realloc etc.
1194 adns_beforepoll (ads, fds, &amp;nfd, &amp;timeout, timeval_from (ev_time ())); 1503 adns_beforepoll (ads, fds, &amp;nfd, &amp;timeout, timeval_from (ev_time ()));
1195 1504
1196 /* the callback is illegal, but won't be called as we stop during check */ 1505 /* the callback is illegal, but won't be called as we stop during check */
1197 ev_timer_init (&amp;tw, 0, timeout * 1e-3); 1506 ev_timer_init (&amp;tw, 0, timeout * 1e-3);
… …
1304 <dd> 1613 <dd>
1305 <p>Make a single, non-blocking sweep over the embedded loop. This works 1614 <p>Make a single, non-blocking sweep over the embedded loop. This works
1306similarly to <code>ev_loop (embedded_loop, EVLOOP_NONBLOCK)</code>, but in the most 1615similarly to <code>ev_loop (embedded_loop, EVLOOP_NONBLOCK)</code>, but in the most
1307apropriate way for embedded loops.</p> 1616apropriate way for embedded loops.</p>
1308 </dd> 1617 </dd>
1618 <dt>struct ev_loop *loop [read-only]</dt>
1619 <dd>
1620 <p>The embedded event loop.</p>
1621 </dd>
1309</dl> 1622</dl>
1310 1623
1311 1624
1312 1625
1313 1626
1314 1627
1315</div> 1628</div>
1316<h1 id="OTHER_FUNCTIONS">OTHER FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p> 1629<h2 id="code_ev_fork_code_the_audacity_to_re"><code>ev_fork</code> - the audacity to resume the event loop after a fork</h2>
1630<div id="code_ev_fork_code_the_audacity_to_re-2">
1631<p>Fork watchers are called when a <code>fork ()</code> was detected (usually because
1632whoever is a good citizen cared to tell libev about it by calling
1633<code>ev_default_fork</code> or <code>ev_loop_fork</code>). The invocation is done before the
1634event loop blocks next and before <code>ev_check</code> watchers are being called,
1635and only in the child after the fork. If whoever good citizen calling
1636<code>ev_default_fork</code> cheats and calls it in the wrong process, the fork
1637handlers will be invoked, too, of course.</p>
1638<dl>
1639 <dt>ev_fork_init (ev_signal *, callback)</dt>
1640 <dd>
1641 <p>Initialises and configures the fork watcher - it has no parameters of any
1642kind. There is a <code>ev_fork_set</code> macro, but using it is utterly pointless,
1643believe me.</p>
1644 </dd>
1645</dl>
1646
1647
1648
1649
1650
1651</div>
1652<h1 id="OTHER_FUNCTIONS">OTHER FUNCTIONS</h1>
1317<div id="OTHER_FUNCTIONS_CONTENT"> 1653<div id="OTHER_FUNCTIONS_CONTENT">
1318<p>There are some other functions of possible interest. Described. Here. Now.</p> 1654<p>There are some other functions of possible interest. Described. Here. Now.</p>
1319<dl> 1655<dl>
1320 <dt>ev_once (loop, int fd, int events, ev_tstamp timeout, callback)</dt> 1656 <dt>ev_once (loop, int fd, int events, ev_tstamp timeout, callback)</dt>
1321 <dd> 1657 <dd>
… …
1368 1704
1369 1705
1370 1706
1371 1707
1372</div> 1708</div>
1373<h1 id="LIBEVENT_EMULATION">LIBEVENT EMULATION</h1><p><a href="#TOP" class="toplink">Top</a></p> 1709<h1 id="LIBEVENT_EMULATION">LIBEVENT EMULATION</h1>
1374<div id="LIBEVENT_EMULATION_CONTENT"> 1710<div id="LIBEVENT_EMULATION_CONTENT">
1375<p>Libev offers a compatibility emulation layer for libevent. It cannot 1711<p>Libev offers a compatibility emulation layer for libevent. It cannot
1376emulate the internals of libevent, so here are some usage hints:</p> 1712emulate the internals of libevent, so here are some usage hints:</p>
1377<dl> 1713<dl>
1378 <dt>* Use it by including &lt;event.h&gt;, as usual.</dt> 1714 <dt>* Use it by including &lt;event.h&gt;, as usual.</dt>
… …
1388 <dt>* The libev emulation is <i>not</i> ABI compatible to libevent, you need 1724 <dt>* The libev emulation is <i>not</i> ABI compatible to libevent, you need
1389to use the libev header file and library.</dt> 1725to use the libev header file and library.</dt>
1390</dl> 1726</dl>
1391 1727
1392</div> 1728</div>
1393<h1 id="C_SUPPORT">C++ SUPPORT</h1><p><a href="#TOP" class="toplink">Top</a></p> 1729<h1 id="C_SUPPORT">C++ SUPPORT</h1>
1394<div id="C_SUPPORT_CONTENT"> 1730<div id="C_SUPPORT_CONTENT">
1395<p>Libev comes with some simplistic wrapper classes for C++ that mainly allow 1731<p>Libev comes with some simplistic wrapper classes for C++ that mainly allow
1396you to use some convinience methods to start/stop watchers and also change 1732you to use some convinience methods to start/stop watchers and also change
1397the callback model to a model using method callbacks on objects.</p> 1733the callback model to a model using method callbacks on objects.</p>
1398<p>To use it,</p> 1734<p>To use it,</p>
… …
1462 </dd> 1798 </dd>
1463 <dt>w-&gt;sweep () <code>ev::embed</code> only</dt> 1799 <dt>w-&gt;sweep () <code>ev::embed</code> only</dt>
1464 <dd> 1800 <dd>
1465 <p>Invokes <code>ev_embed_sweep</code>.</p> 1801 <p>Invokes <code>ev_embed_sweep</code>.</p>
1466 </dd> 1802 </dd>
1803 <dt>w-&gt;update () <code>ev::stat</code> only</dt>
1804 <dd>
1805 <p>Invokes <code>ev_stat_stat</code>.</p>
1806 </dd>
1467 </dl> 1807 </dl>
1468 </p> 1808 </p>
1469 </dd> 1809 </dd>
1470</dl> 1810</dl>
1471<p>Example: Define a class with an IO and idle watcher, start one of them in 1811<p>Example: Define a class with an IO and idle watcher, start one of them in
… …
1483 idle (this, &amp;myclass::idle_cb) 1823 idle (this, &amp;myclass::idle_cb)
1484 { 1824 {
1485 io.start (fd, ev::READ); 1825 io.start (fd, ev::READ);
1486 } 1826 }
1487 1827
1488</pre>
1489 1828
1829
1830
1831</pre>
1832
1490</div> 1833</div>
1491<h1 id="EMBEDDING">EMBEDDING</h1><p><a href="#TOP" class="toplink">Top</a></p> 1834<h1 id="MACRO_MAGIC">MACRO MAGIC</h1>
1835<div id="MACRO_MAGIC_CONTENT">
1836<p>Libev can be compiled with a variety of options, the most fundemantal is
1837<code>EV_MULTIPLICITY</code>. This option determines wether (most) functions and
1838callbacks have an initial <code>struct ev_loop *</code> argument.</p>
1839<p>To make it easier to write programs that cope with either variant, the
1840following macros are defined:</p>
1841<dl>
1842 <dt><code>EV_A</code>, <code>EV_A_</code></dt>
1843 <dd>
1844 <p>This provides the loop <i>argument</i> for functions, if one is required (&quot;ev
1845loop argument&quot;). The <code>EV_A</code> form is used when this is the sole argument,
1846<code>EV_A_</code> is used when other arguments are following. Example:</p>
1847<pre> ev_unref (EV_A);
1848 ev_timer_add (EV_A_ watcher);
1849 ev_loop (EV_A_ 0);
1850
1851</pre>
1852 <p>It assumes the variable <code>loop</code> of type <code>struct ev_loop *</code> is in scope,
1853which is often provided by the following macro.</p>
1854 </dd>
1855 <dt><code>EV_P</code>, <code>EV_P_</code></dt>
1856 <dd>
1857 <p>This provides the loop <i>parameter</i> for functions, if one is required (&quot;ev
1858loop parameter&quot;). The <code>EV_P</code> form is used when this is the sole parameter,
1859<code>EV_P_</code> is used when other parameters are following. Example:</p>
1860<pre> // this is how ev_unref is being declared
1861 static void ev_unref (EV_P);
1862
1863 // this is how you can declare your typical callback
1864 static void cb (EV_P_ ev_timer *w, int revents)
1865
1866</pre>
1867 <p>It declares a parameter <code>loop</code> of type <code>struct ev_loop *</code>, quite
1868suitable for use with <code>EV_A</code>.</p>
1869 </dd>
1870 <dt><code>EV_DEFAULT</code>, <code>EV_DEFAULT_</code></dt>
1871 <dd>
1872 <p>Similar to the other two macros, this gives you the value of the default
1873loop, if multiple loops are supported (&quot;ev loop default&quot;).</p>
1874 </dd>
1875</dl>
1876<p>Example: Declare and initialise a check watcher, utilising the above
1877macros so it will work regardless of wether multiple loops are supported
1878or not.</p>
1879<pre> static void
1880 check_cb (EV_P_ ev_timer *w, int revents)
1881 {
1882 ev_check_stop (EV_A_ w);
1883 }
1884
1885 ev_check check;
1886 ev_check_init (&amp;check, check_cb);
1887 ev_check_start (EV_DEFAULT_ &amp;check);
1888 ev_loop (EV_DEFAULT_ 0);
1889
1890</pre>
1891
1892</div>
1893<h1 id="EMBEDDING">EMBEDDING</h1>
1492<div id="EMBEDDING_CONTENT"> 1894<div id="EMBEDDING_CONTENT">
1493<p>Libev can (and often is) directly embedded into host 1895<p>Libev can (and often is) directly embedded into host
1494applications. Examples of applications that embed it include the Deliantra 1896applications. Examples of applications that embed it include the Deliantra
1495Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe) 1897Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe)
1496and rxvt-unicode.</p> 1898and rxvt-unicode.</p>
… …
1533 ev_vars.h 1935 ev_vars.h
1534 ev_wrap.h 1936 ev_wrap.h
1535 1937
1536 ev_win32.c required on win32 platforms only 1938 ev_win32.c required on win32 platforms only
1537 1939
1538 ev_select.c only when select backend is enabled (which is by default) 1940 ev_select.c only when select backend is enabled (which is enabled by default)
1539 ev_poll.c only when poll backend is enabled (disabled by default) 1941 ev_poll.c only when poll backend is enabled (disabled by default)
1540 ev_epoll.c only when the epoll backend is enabled (disabled by default) 1942 ev_epoll.c only when the epoll backend is enabled (disabled by default)
1541 ev_kqueue.c only when the kqueue backend is enabled (disabled by default) 1943 ev_kqueue.c only when the kqueue backend is enabled (disabled by default)
1542 ev_port.c only when the solaris port backend is enabled (disabled by default) 1944 ev_port.c only when the solaris port backend is enabled (disabled by default)
1543 1945
… …
1670 </dd> 2072 </dd>
1671 <dt>EV_USE_DEVPOLL</dt> 2073 <dt>EV_USE_DEVPOLL</dt>
1672 <dd> 2074 <dd>
1673 <p>reserved for future expansion, works like the USE symbols above.</p> 2075 <p>reserved for future expansion, works like the USE symbols above.</p>
1674 </dd> 2076 </dd>
2077 <dt>EV_USE_INOTIFY</dt>
2078 <dd>
2079 <p>If defined to be <code>1</code>, libev will compile in support for the Linux inotify
2080interface to speed up <code>ev_stat</code> watchers. Its actual availability will
2081be detected at runtime.</p>
2082 </dd>
1675 <dt>EV_H</dt> 2083 <dt>EV_H</dt>
1676 <dd> 2084 <dd>
1677 <p>The name of the <cite>ev.h</cite> header file used to include it. The default if 2085 <p>The name of the <cite>ev.h</cite> header file used to include it. The default if
1678undefined is <code>&lt;ev.h&gt;</code> in <cite>event.h</cite> and <code>&quot;ev.h&quot;</code> in <cite>ev.c</cite>. This 2086undefined is <code>&lt;ev.h&gt;</code> in <cite>event.h</cite> and <code>&quot;ev.h&quot;</code> in <cite>ev.c</cite>. This
1679can be used to virtually rename the <cite>ev.h</cite> header file in case of conflicts.</p> 2087can be used to virtually rename the <cite>ev.h</cite> header file in case of conflicts.</p>
… …
1702will have the <code>struct ev_loop *</code> as first argument, and you can create 2110will have the <code>struct ev_loop *</code> as first argument, and you can create
1703additional independent event loops. Otherwise there will be no support 2111additional independent event loops. Otherwise there will be no support
1704for multiple event loops and there is no first event loop pointer 2112for multiple event loops and there is no first event loop pointer
1705argument. Instead, all functions act on the single default loop.</p> 2113argument. Instead, all functions act on the single default loop.</p>
1706 </dd> 2114 </dd>
1707 <dt>EV_PERIODICS</dt> 2115 <dt>EV_PERIODIC_ENABLE</dt>
1708 <dd> 2116 <dd>
1709 <p>If undefined or defined to be <code>1</code>, then periodic timers are supported, 2117 <p>If undefined or defined to be <code>1</code>, then periodic timers are supported. If
1710otherwise not. This saves a few kb of code.</p> 2118defined to be <code>0</code>, then they are not. Disabling them saves a few kB of
2119code.</p>
2120 </dd>
2121 <dt>EV_IDLE_ENABLE</dt>
2122 <dd>
2123 <p>If undefined or defined to be <code>1</code>, then idle watchers are supported. If
2124defined to be <code>0</code>, then they are not. Disabling them saves a few kB of
2125code.</p>
2126 </dd>
2127 <dt>EV_EMBED_ENABLE</dt>
2128 <dd>
2129 <p>If undefined or defined to be <code>1</code>, then embed watchers are supported. If
2130defined to be <code>0</code>, then they are not.</p>
2131 </dd>
2132 <dt>EV_STAT_ENABLE</dt>
2133 <dd>
2134 <p>If undefined or defined to be <code>1</code>, then stat watchers are supported. If
2135defined to be <code>0</code>, then they are not.</p>
2136 </dd>
2137 <dt>EV_FORK_ENABLE</dt>
2138 <dd>
2139 <p>If undefined or defined to be <code>1</code>, then fork watchers are supported. If
2140defined to be <code>0</code>, then they are not.</p>
2141 </dd>
2142 <dt>EV_MINIMAL</dt>
2143 <dd>
2144 <p>If you need to shave off some kilobytes of code at the expense of some
2145speed, define this symbol to <code>1</code>. Currently only used for gcc to override
2146some inlining decisions, saves roughly 30% codesize of amd64.</p>
2147 </dd>
2148 <dt>EV_PID_HASHSIZE</dt>
2149 <dd>
2150 <p><code>ev_child</code> watchers use a small hash table to distribute workload by
2151pid. The default size is <code>16</code> (or <code>1</code> with <code>EV_MINIMAL</code>), usually more
2152than enough. If you need to manage thousands of children you might want to
2153increase this value (<i>must</i> be a power of two).</p>
2154 </dd>
2155 <dt>EV_INOTIFY_HASHSIZE</dt>
2156 <dd>
2157 <p><code>ev_staz</code> watchers use a small hash table to distribute workload by
2158inotify watch id. The default size is <code>16</code> (or <code>1</code> with <code>EV_MINIMAL</code>),
2159usually more than enough. If you need to manage thousands of <code>ev_stat</code>
2160watchers you might want to increase this value (<i>must</i> be a power of
2161two).</p>
1711 </dd> 2162 </dd>
1712 <dt>EV_COMMON</dt> 2163 <dt>EV_COMMON</dt>
1713 <dd> 2164 <dd>
1714 <p>By default, all watchers have a <code>void *data</code> member. By redefining 2165 <p>By default, all watchers have a <code>void *data</code> member. By redefining
1715this macro to a something else you can include more and other types of 2166this macro to a something else you can include more and other types of
… …
1742the <cite>libev/</cite> subdirectory and includes them in the <cite>EV/EVAPI.h</cite> (public 2193the <cite>libev/</cite> subdirectory and includes them in the <cite>EV/EVAPI.h</cite> (public
1743interface) and <cite>EV.xs</cite> (implementation) files. Only the <cite>EV.xs</cite> file 2194interface) and <cite>EV.xs</cite> (implementation) files. Only the <cite>EV.xs</cite> file
1744will be compiled. It is pretty complex because it provides its own header 2195will be compiled. It is pretty complex because it provides its own header
1745file.</p> 2196file.</p>
1746 <p>The usage in rxvt-unicode is simpler. It has a <cite>ev_cpp.h</cite> header file 2197 <p>The usage in rxvt-unicode is simpler. It has a <cite>ev_cpp.h</cite> header file
1747that everybody includes and which overrides some autoconf choices:</p> 2198that everybody includes and which overrides some configure choices:</p>
2199<pre> #define EV_MINIMAL 1
1748<pre> #define EV_USE_POLL 0 2200 #define EV_USE_POLL 0
1749 #define EV_MULTIPLICITY 0 2201 #define EV_MULTIPLICITY 0
1750 #define EV_PERIODICS 0 2202 #define EV_PERIODIC_ENABLE 0
2203 #define EV_STAT_ENABLE 0
2204 #define EV_FORK_ENABLE 0
1751 #define EV_CONFIG_H &lt;config.h&gt; 2205 #define EV_CONFIG_H &lt;config.h&gt;
2206 #define EV_MINPRI 0
2207 #define EV_MAXPRI 0
1752 2208
1753 #include &quot;ev++.h&quot; 2209 #include &quot;ev++.h&quot;
1754 2210
1755</pre> 2211</pre>
1756 <p>And a <cite>ev_cpp.C</cite> implementation file that contains libev proper and is compiled:</p> 2212 <p>And a <cite>ev_cpp.C</cite> implementation file that contains libev proper and is compiled:</p>
… …
1761 2217
1762 2218
1763</pre> 2219</pre>
1764 2220
1765</div> 2221</div>
1766<h1 id="COMPLEXITIES">COMPLEXITIES</h1><p><a href="#TOP" class="toplink">Top</a></p> 2222<h1 id="COMPLEXITIES">COMPLEXITIES</h1>
1767<div id="COMPLEXITIES_CONTENT"> 2223<div id="COMPLEXITIES_CONTENT">
1768 <p>In this section the complexities of (many of) the algorithms used inside 2224 <p>In this section the complexities of (many of) the algorithms used inside
1769libev will be explained. For complexity discussions about backends see the 2225libev will be explained. For complexity discussions about backends see the
1770documentation for <code>ev_default_init</code>.</p> 2226documentation for <code>ev_default_init</code>.</p>
1771 <p> 2227 <p>
1772 <dl> 2228 <dl>
1773 <dt>Starting and stopping timer/periodic watchers: O(log skipped_other_timers)</dt> 2229 <dt>Starting and stopping timer/periodic watchers: O(log skipped_other_timers)</dt>
1774 <dt>Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)</dt> 2230 <dt>Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)</dt>
1775 <dt>Starting io/check/prepare/idle/signal/child watchers: O(1)</dt> 2231 <dt>Starting io/check/prepare/idle/signal/child watchers: O(1)</dt>
1776 <dt>Stopping check/prepare/idle watchers: O(1)</dt> 2232 <dt>Stopping check/prepare/idle watchers: O(1)</dt>
1777 <dt>Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % 16))</dt> 2233 <dt>Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))</dt>
1778 <dt>Finding the next timer per loop iteration: O(1)</dt> 2234 <dt>Finding the next timer per loop iteration: O(1)</dt>
1779 <dt>Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)</dt> 2235 <dt>Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)</dt>
1780 <dt>Activating one watcher: O(1)</dt> 2236 <dt>Activating one watcher: O(1)</dt>
1781 </dl> 2237 </dl>
1782 </p> 2238 </p>
… …
1784 2240
1785 2241
1786 2242
1787 2243
1788</div> 2244</div>
1789<h1 id="AUTHOR">AUTHOR</h1><p><a href="#TOP" class="toplink">Top</a></p> 2245<h1 id="AUTHOR">AUTHOR</h1>
1790<div id="AUTHOR_CONTENT"> 2246<div id="AUTHOR_CONTENT">
1791 <p>Marc Lehmann &lt;libev@schmorp.de&gt;.</p> 2247 <p>Marc Lehmann &lt;libev@schmorp.de&gt;.</p>
1792 2248
1793</div> 2249</div>
1794</div></body> 2250</div></body>

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