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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 21:14:27 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>
… …
59<li><a href="#AUTHOR">AUTHOR</a> 60<li><a href="#AUTHOR">AUTHOR</a>
60</li> 61</li>
61</ul><hr /> 62</ul><hr />
62<!-- INDEX END --> 63<!-- INDEX END -->
63 64
64<h1 id="NAME">NAME</h1><p><a href="#TOP" class="toplink">Top</a></p> 65<h1 id="NAME">NAME</h1>
65<div id="NAME_CONTENT"> 66<div id="NAME_CONTENT">
66<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>
67 68
68</div> 69</div>
69<h1 id="SYNOPSIS">SYNOPSIS</h1><p><a href="#TOP" class="toplink">Top</a></p> 70<h1 id="SYNOPSIS">SYNOPSIS</h1>
70<div id="SYNOPSIS_CONTENT"> 71<div id="SYNOPSIS_CONTENT">
71<pre> /* this is the only header you need */
72 #include &lt;ev.h&gt; 72<pre> #include &lt;ev.h&gt;
73 73
74 /* what follows is a fully working example program */ 74</pre>
75
76</div>
77<h1 id="EXAMPLE_PROGRAM">EXAMPLE PROGRAM</h1>
78<div id="EXAMPLE_PROGRAM_CONTENT">
79<pre> #include &lt;ev.h&gt;
80
75 ev_io stdin_watcher; 81 ev_io stdin_watcher;
76 ev_timer timeout_watcher; 82 ev_timer timeout_watcher;
77 83
78 /* called when data readable on stdin */ 84 /* called when data readable on stdin */
79 static void 85 static void
… …
111 } 117 }
112 118
113</pre> 119</pre>
114 120
115</div> 121</div>
116<h1 id="DESCRIPTION">DESCRIPTION</h1><p><a href="#TOP" class="toplink">Top</a></p> 122<h1 id="DESCRIPTION">DESCRIPTION</h1>
117<div id="DESCRIPTION_CONTENT"> 123<div id="DESCRIPTION_CONTENT">
118<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
119file descriptor being readable or a timeout occuring), and it will manage 125file descriptor being readable or a timeout occuring), and it will manage
120these event sources and provide your program with events.</p> 126these event sources and provide your program with events.</p>
121<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
… …
125watchers</i>, which are relatively small C structures you initialise with the 131watchers</i>, which are relatively small C structures you initialise with the
126details 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
127watcher.</p> 133watcher.</p>
128 134
129</div> 135</div>
130<h1 id="FEATURES">FEATURES</h1><p><a href="#TOP" class="toplink">Top</a></p> 136<h1 id="FEATURES">FEATURES</h1>
131<div id="FEATURES_CONTENT"> 137<div id="FEATURES_CONTENT">
132<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
133kqueue mechanisms for file descriptor events, relative timers, absolute 139BSD-specific <code>kqueue</code> and the Solaris-specific event port mechanisms
134timers with customised rescheduling, signal events, process status change 140for file descriptor events (<code>ev_io</code>), the Linux <code>inotify</code> interface
135events (related to SIGCHLD), and event watchers dealing with the event 141(for <code>ev_stat</code>), relative timers (<code>ev_timer</code>), absolute timers
136loop 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
137fast (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
138it to libevent for example).</p> 150for example).</p>
139 151
140</div> 152</div>
141<h1 id="CONVENTIONS">CONVENTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p> 153<h1 id="CONVENTIONS">CONVENTIONS</h1>
142<div id="CONVENTIONS_CONTENT"> 154<div id="CONVENTIONS_CONTENT">
143<p>Libev is very configurable. In this manual the default configuration 155<p>Libev is very configurable. In this manual the default configuration will
144will be described, which supports multiple event loops. For more info 156be described, which supports multiple event loops. For more info about
145about various configuration options please have a look at the file 157various configuration options please have a look at <strong>EMBED</strong> section in
146<cite>README.embed</cite> in the libev distribution. If libev was configured without 158this manual. If libev was configured without support for multiple event
147support for multiple event loops, then all functions taking an initial 159loops, then all functions taking an initial argument of name <code>loop</code>
148argument 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>
149will not have this argument.</p>
150 161
151</div> 162</div>
152<h1 id="TIME_REPRESENTATION">TIME REPRESENTATION</h1><p><a href="#TOP" class="toplink">Top</a></p> 163<h1 id="TIME_REPRESENTATION">TIME REPRESENTATION</h1>
153<div id="TIME_REPRESENTATION_CONTENT"> 164<div id="TIME_REPRESENTATION_CONTENT">
154<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
155(fractional) number of seconds since the (POSIX) epoch (somewhere near 166(fractional) number of seconds since the (POSIX) epoch (somewhere near
156the 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
157called <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
158to 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
159it, you should treat it as such.</p> 170it, you should treat it as such.</p>
160 171
161</div> 172</div>
162<h1 id="GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p> 173<h1 id="GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</h1>
163<div id="GLOBAL_FUNCTIONS_CONTENT"> 174<div id="GLOBAL_FUNCTIONS_CONTENT">
164<p>These functions can be called anytime, even before initialising the 175<p>These functions can be called anytime, even before initialising the
165library in any way.</p> 176library in any way.</p>
166<dl> 177<dl>
167 <dt>ev_tstamp ev_time ()</dt> 178 <dt>ev_tstamp ev_time ()</dt>
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180version of the library your program was compiled against.</p> 191version of the library your program was compiled against.</p>
181 <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,
182as this indicates an incompatible change. Minor versions are usually 193as this indicates an incompatible change. Minor versions are usually
183compatible to older versions, so a larger minor version alone is usually 194compatible to older versions, so a larger minor version alone is usually
184not a problem.</p> 195not a problem.</p>
185 <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
186version:</p> 197version.</p>
187<pre> assert ((&quot;libev version mismatch&quot;, 198<pre> assert ((&quot;libev version mismatch&quot;,
188 ev_version_major () == EV_VERSION_MAJOR 199 ev_version_major () == EV_VERSION_MAJOR
189 &amp;&amp; ev_version_minor () &gt;= EV_VERSION_MINOR)); 200 &amp;&amp; ev_version_minor () &gt;= EV_VERSION_MINOR));
190 201
191</pre> 202</pre>
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219might be supported on the current system, you would need to look at 230might be supported on the current system, you would need to look at
220<code>ev_embeddable_backends () &amp; ev_supported_backends ()</code>, likewise for 231<code>ev_embeddable_backends () &amp; ev_supported_backends ()</code>, likewise for
221recommended ones.</p> 232recommended ones.</p>
222 <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>
223 </dd> 234 </dd>
224 <dt>ev_set_allocator (void *(*cb)(void *ptr, size_t size))</dt> 235 <dt>ev_set_allocator (void *(*cb)(void *ptr, long size))</dt>
225 <dd> 236 <dd>
226 <p>Sets the allocation function to use (the prototype and semantics are 237 <p>Sets the allocation function to use (the prototype is similar - the
227identical to the realloc C function). It is used to allocate and free 238semantics is identical - to the realloc C function). It is used to
228memory (no surprises here). If it returns zero when memory needs to be 239allocate and free memory (no surprises here). If it returns zero when
229allocated, the library might abort or take some potentially destructive 240memory needs to be allocated, the library might abort or take some
230action. The default is your system realloc function.</p> 241potentially destructive action. The default is your system realloc
242function.</p>
231 <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,
232free 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,
233or 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>
234 <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
235retries: better than mine).</p> 247retries).</p>
236<pre> static void * 248<pre> static void *
237 persistent_realloc (void *ptr, size_t size) 249 persistent_realloc (void *ptr, size_t size)
238 { 250 {
239 for (;;) 251 for (;;)
240 { 252 {
… …
259indicating the system call or subsystem causing the problem. If this 271indicating the system call or subsystem causing the problem. If this
260callback 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
261matter what, when it returns. That is, libev will generally retry the 273matter what, when it returns. That is, libev will generally retry the
262requested 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
263(such as abort).</p> 275(such as abort).</p>
264 <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>
265<pre> static void 277<pre> static void
266 fatal_error (const char *msg) 278 fatal_error (const char *msg)
267 { 279 {
268 perror (msg); 280 perror (msg);
269 abort (); 281 abort ();
… …
275</pre> 287</pre>
276 </dd> 288 </dd>
277</dl> 289</dl>
278 290
279</div> 291</div>
280<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>
281<div id="FUNCTIONS_CONTROLLING_THE_EVENT_LOOP-2"> 293<div id="FUNCTIONS_CONTROLLING_THE_EVENT_LOOP-2">
282<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
283types 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
284events, and dynamically created loops which do not.</p> 296events, and dynamically created loops which do not.</p>
285<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
… …
313or 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
314<code>LIBEV_FLAGS</code>. Otherwise (the default), this environment variable will 326<code>LIBEV_FLAGS</code>. Otherwise (the default), this environment variable will
315override 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
316useful 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
317around 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>
318 </dd> 347 </dd>
319 <dt><code>EVBACKEND_SELECT</code> (value 1, portable select backend)</dt> 348 <dt><code>EVBACKEND_SELECT</code> (value 1, portable select backend)</dt>
320 <dd> 349 <dd>
321 <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
322libev 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,
… …
405 <dd> 434 <dd>
406 <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
407always distinct from the default loop. Unlike the default loop, it cannot 436always distinct from the default loop. Unlike the default loop, it cannot
408handle 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
409undefined behaviour (or a failed assertion if assertions are enabled).</p> 438undefined behaviour (or a failed assertion if assertions are enabled).</p>
410 <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>
411<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);
412 if (!epoller) 441 if (!epoller)
413 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;);
414 443
415</pre> 444</pre>
… …
451 <dt>ev_loop_fork (loop)</dt> 480 <dt>ev_loop_fork (loop)</dt>
452 <dd> 481 <dd>
453 <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
454<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
455after 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>
456 </dd> 494 </dd>
457 <dt>unsigned int ev_backend (loop)</dt> 495 <dt>unsigned int ev_backend (loop)</dt>
458 <dd> 496 <dd>
459 <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
460use.</p> 498use.</p>
… …
508 be handled here by queueing them when their watcher gets executed. 546 be handled here by queueing them when their watcher gets executed.
509 - 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
510 were used, return, otherwise continue with step *. 548 were used, return, otherwise continue with step *.
511 549
512</pre> 550</pre>
513 <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
514anymore.</p> 552anymore.</p>
515<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
516 ... 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..)
517 ev_loop (my_loop, 0); 555 ev_loop (my_loop, 0);
518 ... jobs done. yeah! 556 ... jobs done. yeah!
… …
537example, 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
538visible 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
539no 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
540way 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
541libraries. 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>
542 <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>
543running when nothing else is active.</p> 581running when nothing else is active.</p>
544<pre> struct dv_signal exitsig; 582<pre> struct ev_signal exitsig;
545 ev_signal_init (&amp;exitsig, sig_cb, SIGINT); 583 ev_signal_init (&amp;exitsig, sig_cb, SIGINT);
546 ev_signal_start (myloop, &amp;exitsig); 584 ev_signal_start (loop, &amp;exitsig);
547 evf_unref (myloop); 585 evf_unref (loop);
548 586
549</pre> 587</pre>
550 <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>
551<pre> ev_ref (myloop); 589<pre> ev_ref (loop);
552 ev_signal_stop (myloop, &amp;exitsig); 590 ev_signal_stop (loop, &amp;exitsig);
553 591
554</pre> 592</pre>
555 </dd> 593 </dd>
556</dl> 594</dl>
557 595
558 596
559 597
560 598
561 599
562</div> 600</div>
563<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>
564<div id="ANATOMY_OF_A_WATCHER_CONTENT"> 602<div id="ANATOMY_OF_A_WATCHER_CONTENT">
565<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
566interest 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
567become 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>
568<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)
… …
731events 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
732is 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
733<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
734libev (e.g. you cnanot <code>free ()</code> it).</p> 772libev (e.g. you cnanot <code>free ()</code> it).</p>
735 </dd> 773 </dd>
736 <dt>callback = ev_cb (ev_TYPE *watcher)</dt> 774 <dt>callback ev_cb (ev_TYPE *watcher)</dt>
737 <dd> 775 <dd>
738 <p>Returns the callback currently set on the watcher.</p> 776 <p>Returns the callback currently set on the watcher.</p>
739 </dd> 777 </dd>
740 <dt>ev_cb_set (ev_TYPE *watcher, callback)</dt> 778 <dt>ev_cb_set (ev_TYPE *watcher, callback)</dt>
741 <dd> 779 <dd>
742 <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
743(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>
744 </dd> 802 </dd>
745</dl> 803</dl>
746 804
747 805
748 806
… …
773 struct my_io *w = (struct my_io *)w_; 831 struct my_io *w = (struct my_io *)w_;
774 ... 832 ...
775 } 833 }
776 834
777</pre> 835</pre>
778<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
779have 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 }
780 846
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;
781 851
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 }
782 858
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 }
783 865
784 866
867
868
869</pre>
870
785</div> 871</div>
786<h1 id="WATCHER_TYPES">WATCHER TYPES</h1><p><a href="#TOP" class="toplink">Top</a></p> 872<h1 id="WATCHER_TYPES">WATCHER TYPES</h1>
787<div id="WATCHER_TYPES_CONTENT"> 873<div id="WATCHER_TYPES_CONTENT">
788<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
789information given in the last section. Any initialisation/set macros, 875information given in the last section. Any initialisation/set macros,
790functions and members specific to the watcher type are explained.</p> 876functions and members specific to the watcher type are explained.</p>
791<p>Members are additionally marked with either <i>[read-only]</i>, meaning that, 877<p>Members are additionally marked with either <i>[read-only]</i>, meaning that,
… …
851 <dt>int events [read-only]</dt> 937 <dt>int events [read-only]</dt>
852 <dd> 938 <dd>
853 <p>The events being watched.</p> 939 <p>The events being watched.</p>
854 </dd> 940 </dd>
855</dl> 941</dl>
856<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
857readable, but only once. Since it is likely line-buffered, you could 943readable, but only once. Since it is likely line-buffered, you could
858attempt to read a whole line in the callback:</p> 944attempt to read a whole line in the callback.</p>
859<pre> static void 945<pre> static void
860 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)
861 { 947 {
862 ev_io_stop (loop, w); 948 ev_io_stop (loop, w);
863 .. 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
… …
912 </dd> 998 </dd>
913 <dt>ev_timer_again (loop)</dt> 999 <dt>ev_timer_again (loop)</dt>
914 <dd> 1000 <dd>
915 <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
916repeating. The exact semantics are:</p> 1002repeating. The exact semantics are:</p>
1003 <p>If the timer is pending, its pending status is cleared.</p>
917 <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>
918 <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
919value), 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>
920 <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
921example: Imagine you have a tcp connection and you want a so-called 1008example: Imagine you have a tcp connection and you want a so-called idle
922idle timeout, that is, you want to be called when there have been, 1009timeout, that is, you want to be called when there have been, say, 60
923say, 60 seconds of inactivity on the socket. The easiest way to do 1010seconds of inactivity on the socket. The easiest way to do this is to
924this is to configure an <code>ev_timer</code> with <code>after</code>=<code>repeat</code>=<code>60</code> and calling 1011configure an <code>ev_timer</code> with a <code>repeat</code> value of <code>60</code> and then call
925<code>ev_timer_again</code> each time you successfully read or write some data. If 1012<code>ev_timer_again</code> each time you successfully read or write some data. If
926you go into an idle state where you do not expect data to travel on the 1013you go into an idle state where you do not expect data to travel on the
927socket, you can stop the timer, and again will automatically restart it if 1014socket, you can <code>ev_timer_stop</code> the timer, and <code>ev_timer_again</code> will
928need be.</p> 1015automatically restart it if need be.</p>
929 <p>You can also ignore the <code>after</code> value and <code>ev_timer_start</code> altogether 1016 <p>That means you can ignore the <code>after</code> value and <code>ev_timer_start</code>
930and only ever use the <code>repeat</code> value:</p> 1017altogether and only ever use the <code>repeat</code> value and <code>ev_timer_again</code>:</p>
931<pre> ev_timer_init (timer, callback, 0., 5.); 1018<pre> ev_timer_init (timer, callback, 0., 5.);
932 ev_timer_again (loop, timer); 1019 ev_timer_again (loop, timer);
933 ... 1020 ...
934 timer-&gt;again = 17.; 1021 timer-&gt;again = 17.;
935 ev_timer_again (loop, timer); 1022 ev_timer_again (loop, timer);
936 ... 1023 ...
937 timer-&gt;again = 10.; 1024 timer-&gt;again = 10.;
938 ev_timer_again (loop, timer); 1025 ev_timer_again (loop, timer);
939 1026
940</pre> 1027</pre>
941 <p>This is more efficient then stopping/starting the timer eahc time you want 1028 <p>This is more slightly efficient then stopping/starting the timer each time
942to modify its timeout value.</p> 1029you want to modify its timeout value.</p>
943 </dd> 1030 </dd>
944 <dt>ev_tstamp repeat [read-write]</dt> 1031 <dt>ev_tstamp repeat [read-write]</dt>
945 <dd> 1032 <dd>
946 <p>The current <code>repeat</code> value. Will be used each time the watcher times out 1033 <p>The current <code>repeat</code> value. Will be used each time the watcher times out
947or <code>ev_timer_again</code> is called and determines the next timeout (if any), 1034or <code>ev_timer_again</code> is called and determines the next timeout (if any),
948which is also when any modifications are taken into account.</p> 1035which is also when any modifications are taken into account.</p>
949 </dd> 1036 </dd>
950</dl> 1037</dl>
951<p>Example: create a timer that fires after 60 seconds.</p> 1038<p>Example: Create a timer that fires after 60 seconds.</p>
952<pre> static void 1039<pre> static void
953 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)
954 { 1041 {
955 .. one minute over, w is actually stopped right here 1042 .. one minute over, w is actually stopped right here
956 } 1043 }
… …
958 struct ev_timer mytimer; 1045 struct ev_timer mytimer;
959 ev_timer_init (&amp;mytimer, one_minute_cb, 60., 0.); 1046 ev_timer_init (&amp;mytimer, one_minute_cb, 60., 0.);
960 ev_timer_start (loop, &amp;mytimer); 1047 ev_timer_start (loop, &amp;mytimer);
961 1048
962</pre> 1049</pre>
963<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
964inactivity.</p> 1051inactivity.</p>
965<pre> static void 1052<pre> static void
966 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)
967 { 1054 {
968 .. ten seconds without any activity 1055 .. ten seconds without any activity
… …
1084 <p>The current reschedule callback, or <code>0</code>, if this functionality is 1171 <p>The current reschedule callback, or <code>0</code>, if this functionality is
1085switched off. Can be changed any time, but changes only take effect when 1172switched off. Can be changed any time, but changes only take effect when
1086the periodic timer fires or <code>ev_periodic_again</code> is being called.</p> 1173the periodic timer fires or <code>ev_periodic_again</code> is being called.</p>
1087 </dd> 1174 </dd>
1088</dl> 1175</dl>
1089<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
1090system clock is divisible by 3600. The callback invocation times have 1177system clock is divisible by 3600. The callback invocation times have
1091potentially a lot of jittering, but good long-term stability.</p> 1178potentially a lot of jittering, but good long-term stability.</p>
1092<pre> static void 1179<pre> static void
1093 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)
1094 { 1181 {
… …
1098 struct ev_periodic hourly_tick; 1185 struct ev_periodic hourly_tick;
1099 ev_periodic_init (&amp;hourly_tick, clock_cb, 0., 3600., 0); 1186 ev_periodic_init (&amp;hourly_tick, clock_cb, 0., 3600., 0);
1100 ev_periodic_start (loop, &amp;hourly_tick); 1187 ev_periodic_start (loop, &amp;hourly_tick);
1101 1188
1102</pre> 1189</pre>
1103<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>
1104<pre> #include &lt;math.h&gt; 1191<pre> #include &lt;math.h&gt;
1105 1192
1106 static ev_tstamp 1193 static ev_tstamp
1107 my_scheduler_cb (struct ev_periodic *w, ev_tstamp now) 1194 my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)
1108 { 1195 {
… …
1110 } 1197 }
1111 1198
1112 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);
1113 1200
1114</pre> 1201</pre>
1115<p>Example: call a callback every hour, starting now:</p> 1202<p>Example: Call a callback every hour, starting now:</p>
1116<pre> struct ev_periodic hourly_tick; 1203<pre> struct ev_periodic hourly_tick;
1117 ev_periodic_init (&amp;hourly_tick, clock_cb, 1204 ev_periodic_init (&amp;hourly_tick, clock_cb,
1118 fmod (ev_now (loop), 3600.), 3600., 0); 1205 fmod (ev_now (loop), 3600.), 3600., 0);
1119 ev_periodic_start (loop, &amp;hourly_tick); 1206 ev_periodic_start (loop, &amp;hourly_tick);
1120 1207
… …
1181 <dd> 1268 <dd>
1182 <p>The process exit/trace status caused by <code>rpid</code> (see your systems 1269 <p>The process exit/trace status caused by <code>rpid</code> (see your systems
1183<code>waitpid</code> and <code>sys/wait.h</code> documentation for details).</p> 1270<code>waitpid</code> and <code>sys/wait.h</code> documentation for details).</p>
1184 </dd> 1271 </dd>
1185</dl> 1272</dl>
1186<p>Example: try to exit cleanly on SIGINT and SIGTERM.</p> 1273<p>Example: Try to exit cleanly on SIGINT and SIGTERM.</p>
1187<pre> static void 1274<pre> static void
1188 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)
1189 { 1276 {
1190 ev_unloop (loop, EVUNLOOP_ALL); 1277 ev_unloop (loop, EVUNLOOP_ALL);
1191 } 1278 }
… …
1208<p>The path does not need to exist: changing from &quot;path exists&quot; to &quot;path does 1295<p>The path does not need to exist: changing from &quot;path exists&quot; to &quot;path does
1209not exist&quot; is a status change like any other. The condition &quot;path does 1296not exist&quot; is a status change like any other. The condition &quot;path does
1210not exist&quot; is signified by the <code>st_nlink</code> field being zero (which is 1297not exist&quot; is signified by the <code>st_nlink</code> field being zero (which is
1211otherwise always forced to be at least one) and all the other fields of 1298otherwise always forced to be at least one) and all the other fields of
1212the stat buffer having unspecified contents.</p> 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>
1213<p>Since there is no standard to do this, the portable implementation simply 1302<p>Since there is no standard to do this, the portable implementation simply
1214calls <code>stat (2)</code> regulalry on the path to see if it changed somehow. You 1303calls <code>stat (2)</code> regularly on the path to see if it changed somehow. You
1215can specify a recommended polling interval for this case. If you specify 1304can specify a recommended polling interval for this case. If you specify
1216a polling interval of <code>0</code> (highly recommended!) then a <i>suitable, 1305a polling interval of <code>0</code> (highly recommended!) then a <i>suitable,
1217unspecified default</i> value will be used (which you can expect to be around 1306unspecified default</i> value will be used (which you can expect to be around
1218five seconds, although this might change dynamically). Libev will also 1307five seconds, although this might change dynamically). Libev will also
1219impose a minimum interval which is currently around <code>0.1</code>, but thats 1308impose a minimum interval which is currently around <code>0.1</code>, but thats
1220usually overkill.</p> 1309usually overkill.</p>
1221<p>This watcher type is not meant for massive numbers of stat watchers, 1310<p>This watcher type is not meant for massive numbers of stat watchers,
1222as even with OS-supported change notifications, this can be 1311as even with OS-supported change notifications, this can be
1223resource-intensive.</p> 1312resource-intensive.</p>
1224<p>At the time of this writing, no specific OS backends are implemented, but 1313<p>At the time of this writing, only the Linux inotify interface is
1225if demand increases, at least a kqueue and inotify backend will be added.</p> 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>
1226<dl> 1320<dl>
1227 <dt>ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)</dt> 1321 <dt>ev_stat_init (ev_stat *, callback, const char *path, ev_tstamp interval)</dt>
1228 <dt>ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)</dt> 1322 <dt>ev_stat_set (ev_stat *, const char *path, ev_tstamp interval)</dt>
1229 <dd> 1323 <dd>
1230 <p>Configures the watcher to wait for status changes of the given 1324 <p>Configures the watcher to wait for status changes of the given
… …
1293</pre> 1387</pre>
1294 1388
1295</div> 1389</div>
1296<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>
1297<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">
1298<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
1299(prepare, check and other idle watchers do not count). That is, as long 1393priority are pending (prepare, check and other idle watchers do not
1300as your process is busy handling sockets or timeouts (or even signals, 1394count).</p>
1301imagine) 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
1302watchers 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
1303until stopped, that is, or your process receives more events and becomes 1399iteration - until stopped, that is, or your process receives more events
1304busy.</p> 1400and becomes busy again with higher priority stuff.</p>
1305<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
1306active, the process will not block when waiting for new events.</p> 1402active, the process will not block when waiting for new events.</p>
1307<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
1308effect 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
1309&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
… …
1314 <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
1315kind. 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,
1316believe me.</p> 1412believe me.</p>
1317 </dd> 1413 </dd>
1318</dl> 1414</dl>
1319<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
1320callback, free it. Alos, use no error checking, as usual.</p> 1416callback, free it. Also, use no error checking, as usual.</p>
1321<pre> static void 1417<pre> static void
1322 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)
1323 { 1419 {
1324 free (w); 1420 free (w);
1325 // now do something you wanted to do when the program has 1421 // now do something you wanted to do when the program has
… …
1399 1495
1400 // create io watchers for each fd and a timer before blocking 1496 // create io watchers for each fd and a timer before blocking
1401 static void 1497 static void
1402 adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents) 1498 adns_prepare_cb (ev_loop *loop, ev_prepare *w, int revents)
1403 { 1499 {
1404 int timeout = 3600000;truct pollfd fds [nfd]; 1500 int timeout = 3600000;
1501 struct pollfd fds [nfd];
1405 // actual code will need to loop here and realloc etc. 1502 // actual code will need to loop here and realloc etc.
1406 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 ()));
1407 1504
1408 /* 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 */
1409 ev_timer_init (&amp;tw, 0, timeout * 1e-3); 1506 ev_timer_init (&amp;tw, 0, timeout * 1e-3);
… …
1550 1647
1551 1648
1552 1649
1553 1650
1554</div> 1651</div>
1555<h1 id="OTHER_FUNCTIONS">OTHER FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p> 1652<h1 id="OTHER_FUNCTIONS">OTHER FUNCTIONS</h1>
1556<div id="OTHER_FUNCTIONS_CONTENT"> 1653<div id="OTHER_FUNCTIONS_CONTENT">
1557<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>
1558<dl> 1655<dl>
1559 <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>
1560 <dd> 1657 <dd>
… …
1607 1704
1608 1705
1609 1706
1610 1707
1611</div> 1708</div>
1612<h1 id="LIBEVENT_EMULATION">LIBEVENT EMULATION</h1><p><a href="#TOP" class="toplink">Top</a></p> 1709<h1 id="LIBEVENT_EMULATION">LIBEVENT EMULATION</h1>
1613<div id="LIBEVENT_EMULATION_CONTENT"> 1710<div id="LIBEVENT_EMULATION_CONTENT">
1614<p>Libev offers a compatibility emulation layer for libevent. It cannot 1711<p>Libev offers a compatibility emulation layer for libevent. It cannot
1615emulate the internals of libevent, so here are some usage hints:</p> 1712emulate the internals of libevent, so here are some usage hints:</p>
1616<dl> 1713<dl>
1617 <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>
… …
1627 <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
1628to use the libev header file and library.</dt> 1725to use the libev header file and library.</dt>
1629</dl> 1726</dl>
1630 1727
1631</div> 1728</div>
1632<h1 id="C_SUPPORT">C++ SUPPORT</h1><p><a href="#TOP" class="toplink">Top</a></p> 1729<h1 id="C_SUPPORT">C++ SUPPORT</h1>
1633<div id="C_SUPPORT_CONTENT"> 1730<div id="C_SUPPORT_CONTENT">
1634<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
1635you 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
1636the callback model to a model using method callbacks on objects.</p> 1733the callback model to a model using method callbacks on objects.</p>
1637<p>To use it,</p> 1734<p>To use it,</p>
… …
1732 1829
1733 1830
1734</pre> 1831</pre>
1735 1832
1736</div> 1833</div>
1737<h1 id="MACRO_MAGIC">MACRO MAGIC</h1><p><a href="#TOP" class="toplink">Top</a></p> 1834<h1 id="MACRO_MAGIC">MACRO MAGIC</h1>
1738<div id="MACRO_MAGIC_CONTENT"> 1835<div id="MACRO_MAGIC_CONTENT">
1739<p>Libev can be compiled with a variety of options, the most fundemantal is 1836<p>Libev can be compiled with a variety of options, the most fundemantal is
1740<code>EV_MULTIPLICITY</code>. This option determines wether (most) functions and 1837<code>EV_MULTIPLICITY</code>. This option determines wether (most) functions and
1741callbacks have an initial <code>struct ev_loop *</code> argument.</p> 1838callbacks have an initial <code>struct ev_loop *</code> argument.</p>
1742<p>To make it easier to write programs that cope with either variant, the 1839<p>To make it easier to write programs that cope with either variant, the
… …
1774 <dd> 1871 <dd>
1775 <p>Similar to the other two macros, this gives you the value of the default 1872 <p>Similar to the other two macros, this gives you the value of the default
1776loop, if multiple loops are supported (&quot;ev loop default&quot;).</p> 1873loop, if multiple loops are supported (&quot;ev loop default&quot;).</p>
1777 </dd> 1874 </dd>
1778</dl> 1875</dl>
1779<p>Example: Declare and initialise a check watcher, working regardless of 1876<p>Example: Declare and initialise a check watcher, utilising the above
1780wether multiple loops are supported or not.</p> 1877macros so it will work regardless of wether multiple loops are supported
1878or not.</p>
1781<pre> static void 1879<pre> static void
1782 check_cb (EV_P_ ev_timer *w, int revents) 1880 check_cb (EV_P_ ev_timer *w, int revents)
1783 { 1881 {
1784 ev_check_stop (EV_A_ w); 1882 ev_check_stop (EV_A_ w);
1785 } 1883 }
… …
1787 ev_check check; 1885 ev_check check;
1788 ev_check_init (&amp;check, check_cb); 1886 ev_check_init (&amp;check, check_cb);
1789 ev_check_start (EV_DEFAULT_ &amp;check); 1887 ev_check_start (EV_DEFAULT_ &amp;check);
1790 ev_loop (EV_DEFAULT_ 0); 1888 ev_loop (EV_DEFAULT_ 0);
1791 1889
1792
1793
1794
1795</pre> 1890</pre>
1796 1891
1797</div> 1892</div>
1798<h1 id="EMBEDDING">EMBEDDING</h1><p><a href="#TOP" class="toplink">Top</a></p> 1893<h1 id="EMBEDDING">EMBEDDING</h1>
1799<div id="EMBEDDING_CONTENT"> 1894<div id="EMBEDDING_CONTENT">
1800<p>Libev can (and often is) directly embedded into host 1895<p>Libev can (and often is) directly embedded into host
1801applications. Examples of applications that embed it include the Deliantra 1896applications. Examples of applications that embed it include the Deliantra
1802Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe) 1897Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe)
1803and rxvt-unicode.</p> 1898and rxvt-unicode.</p>
… …
1840 ev_vars.h 1935 ev_vars.h
1841 ev_wrap.h 1936 ev_wrap.h
1842 1937
1843 ev_win32.c required on win32 platforms only 1938 ev_win32.c required on win32 platforms only
1844 1939
1845 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)
1846 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)
1847 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)
1848 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)
1849 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)
1850 1945
… …
1977 </dd> 2072 </dd>
1978 <dt>EV_USE_DEVPOLL</dt> 2073 <dt>EV_USE_DEVPOLL</dt>
1979 <dd> 2074 <dd>
1980 <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>
1981 </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>
1982 <dt>EV_H</dt> 2083 <dt>EV_H</dt>
1983 <dd> 2084 <dd>
1984 <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
1985undefined 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
1986can 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>
… …
2015 <dd> 2116 <dd>
2016 <p>If undefined or defined to be <code>1</code>, then periodic timers are supported. If 2117 <p>If undefined or defined to be <code>1</code>, then periodic timers are supported. If
2017defined to be <code>0</code>, then they are not. Disabling them saves a few kB of 2118defined to be <code>0</code>, then they are not. Disabling them saves a few kB of
2018code.</p> 2119code.</p>
2019 </dd> 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>
2020 <dt>EV_EMBED_ENABLE</dt> 2127 <dt>EV_EMBED_ENABLE</dt>
2021 <dd> 2128 <dd>
2022 <p>If undefined or defined to be <code>1</code>, then embed watchers are supported. If 2129 <p>If undefined or defined to be <code>1</code>, then embed watchers are supported. If
2023defined to be <code>0</code>, then they are not.</p> 2130defined to be <code>0</code>, then they are not.</p>
2024 </dd> 2131 </dd>
… …
2041 <dt>EV_PID_HASHSIZE</dt> 2148 <dt>EV_PID_HASHSIZE</dt>
2042 <dd> 2149 <dd>
2043 <p><code>ev_child</code> watchers use a small hash table to distribute workload by 2150 <p><code>ev_child</code> watchers use a small hash table to distribute workload by
2044pid. The default size is <code>16</code> (or <code>1</code> with <code>EV_MINIMAL</code>), usually more 2151pid. The default size is <code>16</code> (or <code>1</code> with <code>EV_MINIMAL</code>), usually more
2045than enough. If you need to manage thousands of children you might want to 2152than enough. If you need to manage thousands of children you might want to
2046increase this value.</p> 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>
2047 </dd> 2162 </dd>
2048 <dt>EV_COMMON</dt> 2163 <dt>EV_COMMON</dt>
2049 <dd> 2164 <dd>
2050 <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
2051this 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
… …
2078the <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
2079interface) 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
2080will 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
2081file.</p> 2196file.</p>
2082 <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
2083that 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
2084<pre> #define EV_USE_POLL 0 2200 #define EV_USE_POLL 0
2085 #define EV_MULTIPLICITY 0 2201 #define EV_MULTIPLICITY 0
2086 #define EV_PERIODICS 0 2202 #define EV_PERIODIC_ENABLE 0
2203 #define EV_STAT_ENABLE 0
2204 #define EV_FORK_ENABLE 0
2087 #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
2088 2208
2089 #include &quot;ev++.h&quot; 2209 #include &quot;ev++.h&quot;
2090 2210
2091</pre> 2211</pre>
2092 <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>
… …
2097 2217
2098 2218
2099</pre> 2219</pre>
2100 2220
2101</div> 2221</div>
2102<h1 id="COMPLEXITIES">COMPLEXITIES</h1><p><a href="#TOP" class="toplink">Top</a></p> 2222<h1 id="COMPLEXITIES">COMPLEXITIES</h1>
2103<div id="COMPLEXITIES_CONTENT"> 2223<div id="COMPLEXITIES_CONTENT">
2104 <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
2105libev will be explained. For complexity discussions about backends see the 2225libev will be explained. For complexity discussions about backends see the
2106documentation for <code>ev_default_init</code>.</p> 2226documentation for <code>ev_default_init</code>.</p>
2107 <p> 2227 <p>
2108 <dl> 2228 <dl>
2109 <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>
2110 <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>
2111 <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>
2112 <dt>Stopping check/prepare/idle watchers: O(1)</dt> 2232 <dt>Stopping check/prepare/idle watchers: O(1)</dt>
2113 <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>
2114 <dt>Finding the next timer per loop iteration: O(1)</dt> 2234 <dt>Finding the next timer per loop iteration: O(1)</dt>
2115 <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>
2116 <dt>Activating one watcher: O(1)</dt> 2236 <dt>Activating one watcher: O(1)</dt>
2117 </dl> 2237 </dl>
2118 </p> 2238 </p>
… …
2120 2240
2121 2241
2122 2242
2123 2243
2124</div> 2244</div>
2125<h1 id="AUTHOR">AUTHOR</h1><p><a href="#TOP" class="toplink">Top</a></p> 2245<h1 id="AUTHOR">AUTHOR</h1>
2126<div id="AUTHOR_CONTENT"> 2246<div id="AUTHOR_CONTENT">
2127 <p>Marc Lehmann &lt;libev@schmorp.de&gt;.</p> 2247 <p>Marc Lehmann &lt;libev@schmorp.de&gt;.</p>
2128 2248
2129</div> 2249</div>
2130</div></body> 2250</div></body>

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