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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="<standard input>" />	7	<meta name="inputfile" content="<standard input>" />
8	<meta name="outputfile" content="<standard output>" />	8	<meta name="outputfile" content="<standard output>" />
9	<meta name="created" content="Sat Nov 24 17:57:37 2007" />	9	<meta name="created" content="Tue Nov 27 21:26:46 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>
…		…
50	</li>	54	</li>
51	<li><a href="#PREPROCESSOR_SYMBOLS_MACROS">PREPROCESSOR SYMBOLS/MACROS</a></li>	55	<li><a href="#PREPROCESSOR_SYMBOLS_MACROS">PREPROCESSOR SYMBOLS/MACROS</a></li>
52	<li><a href="#EXAMPLES">EXAMPLES</a></li>	56	<li><a href="#EXAMPLES">EXAMPLES</a></li>
53	</ul>	57	</ul>
54	</li>	58	</li>
		59	<li><a href="#COMPLEXITIES">COMPLEXITIES</a></li>
55	<li><a href="#AUTHOR">AUTHOR</a>	60	<li><a href="#AUTHOR">AUTHOR</a>
56	</li>	61	</li>
57	</ul><hr />	62	</ul><hr />
58	<!-- INDEX END -->	63	<!-- INDEX END -->
59		64
…		…
63		68
64	</div>	69	</div>
65	<h1 id="SYNOPSIS">SYNOPSIS</h1><p><a href="#TOP" class="toplink">Top</a></p>	70	<h1 id="SYNOPSIS">SYNOPSIS</h1><p><a href="#TOP" class="toplink">Top</a></p>
66	<div id="SYNOPSIS_CONTENT">	71	<div id="SYNOPSIS_CONTENT">
67	<pre> #include <ev.h>	72	<pre> #include <ev.h>
		73
		74	</pre>
		75
		76	</div>
		77	<h1 id="EXAMPLE_PROGRAM">EXAMPLE PROGRAM</h1><p><a href="#TOP" class="toplink">Top</a></p>
		78	<div id="EXAMPLE_PROGRAM_CONTENT">
		79	<pre> #include <ev.h>
		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 ("stdin ready"); */
		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 ("timeout"); */
		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 (&stdin_watcher, stdin_cb, /STDIN_FILENO/ 0, EV_READ);
		107	ev_io_start (loop, &stdin_watcher);
		108
		109	/* simple non-repeating 5.5 second timeout */
		110	ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.);
		111	ev_timer_start (loop, &timeout_watcher);
		112
		113	/* loop till timeout or data ready */
		114	ev_loop (loop, 0);
		115
		116	return 0;
		117	}
68		118
69	</pre>	119	</pre>
70		120
71	</div>	121	</div>
72	<h1 id="DESCRIPTION">DESCRIPTION</h1><p><a href="#TOP" class="toplink">Top</a></p>	122	<h1 id="DESCRIPTION">DESCRIPTION</h1><p><a href="#TOP" class="toplink">Top</a></p>
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83	watcher.</p>	133	watcher.</p>
84		134
85	</div>	135	</div>
86	<h1 id="FEATURES">FEATURES</h1><p><a href="#TOP" class="toplink">Top</a></p>	136	<h1 id="FEATURES">FEATURES</h1><p><a href="#TOP" class="toplink">Top</a></p>
87	<div id="FEATURES_CONTENT">	137	<div id="FEATURES_CONTENT">
88	<p>Libev supports select, poll, the linux-specific epoll and the bsd-specific	138	<p>Libev supports <code>select</code>, <code>poll</code>, the linux-specific <code>epoll</code>, the
89	kqueue mechanisms for file descriptor events, relative timers, absolute	139	bsd-specific <code>kqueue</code> and the solaris-specific event port mechanisms
90	timers with customised rescheduling, signal events, process status change	140	for file descriptor events (<code>ev_io</code>), relative timers (<code>ev_timer</code>),
91	events (related to SIGCHLD), and event watchers dealing with the event	141	absolute timers with customised rescheduling (<code>ev_periodic</code>), synchronous
92	loop mechanism itself (idle, prepare and check watchers). It also is quite	142	signals (<code>ev_signal</code>), process status change events (<code>ev_child</code>), and
		143	event watchers dealing with the event loop mechanism itself (<code>ev_idle</code>,
		144	<code>ev_embed</code>, <code>ev_prepare</code> and <code>ev_check</code> watchers) as well as
		145	file watchers (<code>ev_stat</code>) and even limited support for fork events
		146	(<code>ev_fork</code>).</p>
		147	<p>It also is quite fast (see this
93	fast (see this <a href="http://libev.schmorp.de/bench.html">benchmark</a> comparing	148	<a href="http://libev.schmorp.de/bench.html">benchmark</a> comparing it to libevent
94	it to libevent for example).</p>	149	for example).</p>
95		150
96	</div>	151	</div>
97	<h1 id="CONVENTIONS">CONVENTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p>	152	<h1 id="CONVENTIONS">CONVENTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p>
98	<div id="CONVENTIONS_CONTENT">	153	<div id="CONVENTIONS_CONTENT">
99	<p>Libev is very configurable. In this manual the default configuration	154	<p>Libev is very configurable. In this manual the default configuration will
100	will be described, which supports multiple event loops. For more info	155	be described, which supports multiple event loops. For more info about
101	about various configuration options please have a look at the file	156	various configuration options please have a look at <strong>EMBED</strong> section in
102	<cite>README.embed</cite> in the libev distribution. If libev was configured without	157	this manual. If libev was configured without support for multiple event
103	support for multiple event loops, then all functions taking an initial	158	loops, then all functions taking an initial argument of name <code>loop</code>
104	argument of name <code>loop</code> (which is always of type <code>struct ev_loop *</code>)	159	(which is always of type <code>struct ev_loop *</code>) will not have this argument.</p>
105	will not have this argument.</p>
106		160
107	</div>	161	</div>
108	<h1 id="TIME_REPRESENTATION">TIME REPRESENTATION</h1><p><a href="#TOP" class="toplink">Top</a></p>	162	<h1 id="TIME_REPRESENTATION">TIME REPRESENTATION</h1><p><a href="#TOP" class="toplink">Top</a></p>
109	<div id="TIME_REPRESENTATION_CONTENT">	163	<div id="TIME_REPRESENTATION_CONTENT">
110	<p>Libev represents time as a single floating point number, representing the	164	<p>Libev represents time as a single floating point number, representing the
111	(fractional) number of seconds since the (POSIX) epoch (somewhere near	165	(fractional) number of seconds since the (POSIX) epoch (somewhere near
112	the beginning of 1970, details are complicated, don't ask). This type is	166	the beginning of 1970, details are complicated, don't ask). This type is
113	called <code>ev_tstamp</code>, which is what you should use too. It usually aliases	167	called <code>ev_tstamp</code>, which is what you should use too. It usually aliases
114	to the <code>double</code> type in C, and when you need to do any calculations on	168	to the <code>double</code> type in C, and when you need to do any calculations on
115	it, you should treat it as such.</p>	169	it, you should treat it as such.</p>
116
117
118
119
120		170
121	</div>	171	</div>
122	<h1 id="GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p>	172	<h1 id="GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p>
123	<div id="GLOBAL_FUNCTIONS_CONTENT">	173	<div id="GLOBAL_FUNCTIONS_CONTENT">
124	<p>These functions can be called anytime, even before initialising the	174	<p>These functions can be called anytime, even before initialising the
…		…
140	version of the library your program was compiled against.</p>	190	version of the library your program was compiled against.</p>
141	<p>Usually, it's a good idea to terminate if the major versions mismatch,	191	<p>Usually, it's a good idea to terminate if the major versions mismatch,
142	as this indicates an incompatible change. Minor versions are usually	192	as this indicates an incompatible change. Minor versions are usually
143	compatible to older versions, so a larger minor version alone is usually	193	compatible to older versions, so a larger minor version alone is usually
144	not a problem.</p>	194	not a problem.</p>
145	<p>Example: make sure we haven't accidentally been linked against the wrong	195	<p>Example: Make sure we haven't accidentally been linked against the wrong
146	version:</p>	196	version.</p>
147	<pre> assert (("libev version mismatch",	197	<pre> assert (("libev version mismatch",
148	ev_version_major () == EV_VERSION_MAJOR	198	ev_version_major () == EV_VERSION_MAJOR
149	&& ev_version_minor () >= EV_VERSION_MINOR));	199	&& ev_version_minor () >= EV_VERSION_MINOR));
150		200
151	</pre>	201	</pre>
…		…
179	might be supported on the current system, you would need to look at	229	might be supported on the current system, you would need to look at
180	<code>ev_embeddable_backends () & ev_supported_backends ()</code>, likewise for	230	<code>ev_embeddable_backends () & ev_supported_backends ()</code>, likewise for
181	recommended ones.</p>	231	recommended ones.</p>
182	<p>See the description of <code>ev_embed</code> watchers for more info.</p>	232	<p>See the description of <code>ev_embed</code> watchers for more info.</p>
183	</dd>	233	</dd>
184	<dt>ev_set_allocator (void (cb)(void *ptr, long size))</dt>	234	<dt>ev_set_allocator (void (cb)(void *ptr, size_t size))</dt>
185	<dd>	235	<dd>
186	<p>Sets the allocation function to use (the prototype is similar to the	236	<p>Sets the allocation function to use (the prototype and semantics are
187	realloc C function, the semantics are identical). It is used to allocate	237	identical to the realloc C function). It is used to allocate and free
188	and free memory (no surprises here). If it returns zero when memory	238	memory (no surprises here). If it returns zero when memory needs to be
189	needs to be allocated, the library might abort or take some potentially	239	allocated, the library might abort or take some potentially destructive
190	destructive action. The default is your system realloc function.</p>	240	action. The default is your system realloc function.</p>
191	<p>You could override this function in high-availability programs to, say,	241	<p>You could override this function in high-availability programs to, say,
192	free some memory if it cannot allocate memory, to use a special allocator,	242	free some memory if it cannot allocate memory, to use a special allocator,
193	or even to sleep a while and retry until some memory is available.</p>	243	or even to sleep a while and retry until some memory is available.</p>
194	<p>Example: replace the libev allocator with one that waits a bit and then	244	<p>Example: Replace the libev allocator with one that waits a bit and then
195	retries: better than mine).</p>	245	retries).</p>
196	<pre> static void *	246	<pre> static void *
197	persistent_realloc (void *ptr, long size)	247	persistent_realloc (void *ptr, size_t size)
198	{	248	{
199	for (;;)	249	for (;;)
200	{	250	{
201	void *newptr = realloc (ptr, size);	251	void *newptr = realloc (ptr, size);
202		252
…		…
219	indicating the system call or subsystem causing the problem. If this	269	indicating the system call or subsystem causing the problem. If this
220	callback is set, then libev will expect it to remedy the sitution, no	270	callback is set, then libev will expect it to remedy the sitution, no
221	matter what, when it returns. That is, libev will generally retry the	271	matter what, when it returns. That is, libev will generally retry the
222	requested operation, or, if the condition doesn't go away, do bad stuff	272	requested operation, or, if the condition doesn't go away, do bad stuff
223	(such as abort).</p>	273	(such as abort).</p>
224	<p>Example: do the same thing as libev does internally:</p>	274	<p>Example: This is basically the same thing that libev does internally, too.</p>
225	<pre> static void	275	<pre> static void
226	fatal_error (const char *msg)	276	fatal_error (const char *msg)
227	{	277	{
228	perror (msg);	278	perror (msg);
229	abort ();	279	abort ();
…		…
365	<dd>	415	<dd>
366	<p>Similar to <code>ev_default_loop</code>, but always creates a new event loop that is	416	<p>Similar to <code>ev_default_loop</code>, but always creates a new event loop that is
367	always distinct from the default loop. Unlike the default loop, it cannot	417	always distinct from the default loop. Unlike the default loop, it cannot
368	handle signal and child watchers, and attempts to do so will be greeted by	418	handle signal and child watchers, and attempts to do so will be greeted by
369	undefined behaviour (or a failed assertion if assertions are enabled).</p>	419	undefined behaviour (or a failed assertion if assertions are enabled).</p>
370	<p>Example: try to create a event loop that uses epoll and nothing else.</p>	420	<p>Example: Try to create a event loop that uses epoll and nothing else.</p>
371	<pre> struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL \| EVFLAG_NOENV);	421	<pre> struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL \| EVFLAG_NOENV);
372	if (!epoller)	422	if (!epoller)
373	fatal ("no epoll found here, maybe it hides under your chair");	423	fatal ("no epoll found here, maybe it hides under your chair");
374		424
375	</pre>	425	</pre>
…		…
468	be handled here by queueing them when their watcher gets executed.	518	be handled here by queueing them when their watcher gets executed.
469	- If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK	519	- If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK
470	were used, return, otherwise continue with step *.	520	were used, return, otherwise continue with step *.
471		521
472	</pre>	522	</pre>
473	<p>Example: queue some jobs and then loop until no events are outsanding	523	<p>Example: Queue some jobs and then loop until no events are outsanding
474	anymore.</p>	524	anymore.</p>
475	<pre> ... queue jobs here, make sure they register event watchers as long	525	<pre> ... queue jobs here, make sure they register event watchers as long
476	... as they still have work to do (even an idle watcher will do..)	526	... as they still have work to do (even an idle watcher will do..)
477	ev_loop (my_loop, 0);	527	ev_loop (my_loop, 0);
478	... jobs done. yeah!	528	... jobs done. yeah!
…		…
497	example, libev itself uses this for its internal signal pipe: It is not	547	example, libev itself uses this for its internal signal pipe: It is not
498	visible to the libev user and should not keep <code>ev_loop</code> from exiting if	548	visible to the libev user and should not keep <code>ev_loop</code> from exiting if
499	no event watchers registered by it are active. It is also an excellent	549	no event watchers registered by it are active. It is also an excellent
500	way to do this for generic recurring timers or from within third-party	550	way to do this for generic recurring timers or from within third-party
501	libraries. Just remember to <i>unref after start</i> and <i>ref before stop</i>.</p>	551	libraries. Just remember to <i>unref after start</i> and <i>ref before stop</i>.</p>
502	<p>Example: create a signal watcher, but keep it from keeping <code>ev_loop</code>	552	<p>Example: Create a signal watcher, but keep it from keeping <code>ev_loop</code>
503	running when nothing else is active.</p>	553	running when nothing else is active.</p>
504	<pre> struct dv_signal exitsig;	554	<pre> struct ev_signal exitsig;
505	ev_signal_init (&exitsig, sig_cb, SIGINT);	555	ev_signal_init (&exitsig, sig_cb, SIGINT);
506	ev_signal_start (myloop, &exitsig);	556	ev_signal_start (loop, &exitsig);
507	evf_unref (myloop);	557	evf_unref (loop);
508		558
509	</pre>	559	</pre>
510	<p>Example: for some weird reason, unregister the above signal handler again.</p>	560	<p>Example: For some weird reason, unregister the above signal handler again.</p>
511	<pre> ev_ref (myloop);	561	<pre> ev_ref (loop);
512	ev_signal_stop (myloop, &exitsig);	562	ev_signal_stop (loop, &exitsig);
513		563
514	</pre>	564	</pre>
515	</dd>	565	</dd>
516	</dl>	566	</dl>
517		567
…		…
585	</dd>	635	</dd>
586	<dt><code>EV_CHILD</code></dt>	636	<dt><code>EV_CHILD</code></dt>
587	<dd>	637	<dd>
588	<p>The pid specified in the <code>ev_child</code> watcher has received a status change.</p>	638	<p>The pid specified in the <code>ev_child</code> watcher has received a status change.</p>
589	</dd>	639	</dd>
		640	<dt><code>EV_STAT</code></dt>
		641	<dd>
		642	<p>The path specified in the <code>ev_stat</code> watcher changed its attributes somehow.</p>
		643	</dd>
590	<dt><code>EV_IDLE</code></dt>	644	<dt><code>EV_IDLE</code></dt>
591	<dd>	645	<dd>
592	<p>The <code>ev_idle</code> watcher has determined that you have nothing better to do.</p>	646	<p>The <code>ev_idle</code> watcher has determined that you have nothing better to do.</p>
593	</dd>	647	</dd>
594	<dt><code>EV_PREPARE</code></dt>	648	<dt><code>EV_PREPARE</code></dt>
…		…
599	<code>ev_loop</code> has gathered them, but before it invokes any callbacks for any	653	<code>ev_loop</code> has gathered them, but before it invokes any callbacks for any
600	received events. Callbacks of both watcher types can start and stop as	654	received events. Callbacks of both watcher types can start and stop as
601	many watchers as they want, and all of them will be taken into account	655	many watchers as they want, and all of them will be taken into account
602	(for example, a <code>ev_prepare</code> watcher might start an idle watcher to keep	656	(for example, a <code>ev_prepare</code> watcher might start an idle watcher to keep
603	<code>ev_loop</code> from blocking).</p>	657	<code>ev_loop</code> from blocking).</p>
		658	</dd>
		659	<dt><code>EV_EMBED</code></dt>
		660	<dd>
		661	<p>The embedded event loop specified in the <code>ev_embed</code> watcher needs attention.</p>
		662	</dd>
		663	<dt><code>EV_FORK</code></dt>
		664	<dd>
		665	<p>The event loop has been resumed in the child process after fork (see
		666	<code>ev_fork</code>).</p>
604	</dd>	667	</dd>
605	<dt><code>EV_ERROR</code></dt>	668	<dt><code>EV_ERROR</code></dt>
606	<dd>	669	<dd>
607	<p>An unspecified error has occured, the watcher has been stopped. This might	670	<p>An unspecified error has occured, the watcher has been stopped. This might
608	happen because the watcher could not be properly started because libev	671	happen because the watcher could not be properly started because libev
…		…
731		794
732	</div>	795	</div>
733	<h1 id="WATCHER_TYPES">WATCHER TYPES</h1><p><a href="#TOP" class="toplink">Top</a></p>	796	<h1 id="WATCHER_TYPES">WATCHER TYPES</h1><p><a href="#TOP" class="toplink">Top</a></p>
734	<div id="WATCHER_TYPES_CONTENT">	797	<div id="WATCHER_TYPES_CONTENT">
735	<p>This section describes each watcher in detail, but will not repeat	798	<p>This section describes each watcher in detail, but will not repeat
736	information given in the last section.</p>	799	information given in the last section. Any initialisation/set macros,
		800	functions and members specific to the watcher type are explained.</p>
		801	<p>Members are additionally marked with either <i>[read-only]</i>, meaning that,
		802	while the watcher is active, you can look at the member and expect some
		803	sensible content, but you must not modify it (you can modify it while the
		804	watcher is stopped to your hearts content), or <i>[read-write]</i>, which
		805	means you can expect it to have some sensible content while the watcher
		806	is active, but you can also modify it. Modifying it may not do something
		807	sensible or take immediate effect (or do anything at all), but libev will
		808	not crash or malfunction in any way.</p>
737		809
738		810
739		811
740		812
741		813
…		…
780	<dd>	852	<dd>
781	<p>Configures an <code>ev_io</code> watcher. The <code>fd</code> is the file descriptor to	853	<p>Configures an <code>ev_io</code> watcher. The <code>fd</code> is the file descriptor to
782	rceeive events for and events is either <code>EV_READ</code>, <code>EV_WRITE</code> or	854	rceeive events for and events is either <code>EV_READ</code>, <code>EV_WRITE</code> or
783	<code>EV_READ \| EV_WRITE</code> to receive the given events.</p>	855	<code>EV_READ \| EV_WRITE</code> to receive the given events.</p>
784	</dd>	856	</dd>
		857	<dt>int fd [read-only]</dt>
		858	<dd>
		859	<p>The file descriptor being watched.</p>
		860	</dd>
		861	<dt>int events [read-only]</dt>
		862	<dd>
		863	<p>The events being watched.</p>
		864	</dd>
785	</dl>	865	</dl>
786	<p>Example: call <code>stdin_readable_cb</code> when STDIN_FILENO has become, well	866	<p>Example: Call <code>stdin_readable_cb</code> when STDIN_FILENO has become, well
787	readable, but only once. Since it is likely line-buffered, you could	867	readable, but only once. Since it is likely line-buffered, you could
788	attempt to read a whole line in the callback:</p>	868	attempt to read a whole line in the callback.</p>
789	<pre> static void	869	<pre> static void
790	stdin_readable_cb (struct ev_loop loop, struct ev_io w, int revents)	870	stdin_readable_cb (struct ev_loop loop, struct ev_io w, int revents)
791	{	871	{
792	ev_io_stop (loop, w);	872	ev_io_stop (loop, w);
793	.. read from stdin here (or from w->fd) and haqndle any I/O errors	873	.. read from stdin here (or from w->fd) and haqndle any I/O errors
…		…
846	repeating. The exact semantics are:</p>	926	repeating. The exact semantics are:</p>
847	<p>If the timer is started but nonrepeating, stop it.</p>	927	<p>If the timer is started but nonrepeating, stop it.</p>
848	<p>If the timer is repeating, either start it if necessary (with the repeat	928	<p>If the timer is repeating, either start it if necessary (with the repeat
849	value), or reset the running timer to the repeat value.</p>	929	value), or reset the running timer to the repeat value.</p>
850	<p>This sounds a bit complicated, but here is a useful and typical	930	<p>This sounds a bit complicated, but here is a useful and typical
851	example: Imagine you have a tcp connection and you want a so-called idle	931	example: Imagine you have a tcp connection and you want a so-called
852	timeout, that is, you want to be called when there have been, say, 60	932	idle timeout, that is, you want to be called when there have been,
853	seconds of inactivity on the socket. The easiest way to do this is to	933	say, 60 seconds of inactivity on the socket. The easiest way to do
854	configure an <code>ev_timer</code> with after=repeat=60 and calling ev_timer_again each	934	this is to configure an <code>ev_timer</code> with <code>after</code>=<code>repeat</code>=<code>60</code> and calling
855	time you successfully read or write some data. If you go into an idle	935	<code>ev_timer_again</code> each time you successfully read or write some data. If
856	state where you do not expect data to travel on the socket, you can stop	936	you go into an idle state where you do not expect data to travel on the
857	the timer, and again will automatically restart it if need be.</p>	937	socket, you can stop the timer, and again will automatically restart it if
		938	need be.</p>
		939	<p>You can also ignore the <code>after</code> value and <code>ev_timer_start</code> altogether
		940	and only ever use the <code>repeat</code> value:</p>
		941	<pre> ev_timer_init (timer, callback, 0., 5.);
		942	ev_timer_again (loop, timer);
		943	...
		944	timer->again = 17.;
		945	ev_timer_again (loop, timer);
		946	...
		947	timer->again = 10.;
		948	ev_timer_again (loop, timer);
		949
		950	</pre>
		951	<p>This is more efficient then stopping/starting the timer eahc time you want
		952	to modify its timeout value.</p>
		953	</dd>
		954	<dt>ev_tstamp repeat [read-write]</dt>
		955	<dd>
		956	<p>The current <code>repeat</code> value. Will be used each time the watcher times out
		957	or <code>ev_timer_again</code> is called and determines the next timeout (if any),
		958	which is also when any modifications are taken into account.</p>
858	</dd>	959	</dd>
859	</dl>	960	</dl>
860	<p>Example: create a timer that fires after 60 seconds.</p>	961	<p>Example: Create a timer that fires after 60 seconds.</p>
861	<pre> static void	962	<pre> static void
862	one_minute_cb (struct ev_loop loop, struct ev_timer w, int revents)	963	one_minute_cb (struct ev_loop loop, struct ev_timer w, int revents)
863	{	964	{
864	.. one minute over, w is actually stopped right here	965	.. one minute over, w is actually stopped right here
865	}	966	}
…		…
867	struct ev_timer mytimer;	968	struct ev_timer mytimer;
868	ev_timer_init (&mytimer, one_minute_cb, 60., 0.);	969	ev_timer_init (&mytimer, one_minute_cb, 60., 0.);
869	ev_timer_start (loop, &mytimer);	970	ev_timer_start (loop, &mytimer);
870		971
871	</pre>	972	</pre>
872	<p>Example: create a timeout timer that times out after 10 seconds of	973	<p>Example: Create a timeout timer that times out after 10 seconds of
873	inactivity.</p>	974	inactivity.</p>
874	<pre> static void	975	<pre> static void
875	timeout_cb (struct ev_loop loop, struct ev_timer w, int revents)	976	timeout_cb (struct ev_loop loop, struct ev_timer w, int revents)
876	{	977	{
877	.. ten seconds without any activity	978	.. ten seconds without any activity
…		…
980	<p>Simply stops and restarts the periodic watcher again. This is only useful	1081	<p>Simply stops and restarts the periodic watcher again. This is only useful
981	when you changed some parameters or the reschedule callback would return	1082	when you changed some parameters or the reschedule callback would return
982	a different time than the last time it was called (e.g. in a crond like	1083	a different time than the last time it was called (e.g. in a crond like
983	program when the crontabs have changed).</p>	1084	program when the crontabs have changed).</p>
984	</dd>	1085	</dd>
		1086	<dt>ev_tstamp interval [read-write]</dt>
		1087	<dd>
		1088	<p>The current interval value. Can be modified any time, but changes only
		1089	take effect when the periodic timer fires or <code>ev_periodic_again</code> is being
		1090	called.</p>
		1091	</dd>
		1092	<dt>ev_tstamp (reschedule_cb)(struct ev_periodic w, ev_tstamp now) [read-write]</dt>
		1093	<dd>
		1094	<p>The current reschedule callback, or <code>0</code>, if this functionality is
		1095	switched off. Can be changed any time, but changes only take effect when
		1096	the periodic timer fires or <code>ev_periodic_again</code> is being called.</p>
		1097	</dd>
985	</dl>	1098	</dl>
986	<p>Example: call a callback every hour, or, more precisely, whenever the	1099	<p>Example: Call a callback every hour, or, more precisely, whenever the
987	system clock is divisible by 3600. The callback invocation times have	1100	system clock is divisible by 3600. The callback invocation times have
988	potentially a lot of jittering, but good long-term stability.</p>	1101	potentially a lot of jittering, but good long-term stability.</p>
989	<pre> static void	1102	<pre> static void
990	clock_cb (struct ev_loop loop, struct ev_io w, int revents)	1103	clock_cb (struct ev_loop loop, struct ev_io w, int revents)
991	{	1104	{
…		…
995	struct ev_periodic hourly_tick;	1108	struct ev_periodic hourly_tick;
996	ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);	1109	ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);
997	ev_periodic_start (loop, &hourly_tick);	1110	ev_periodic_start (loop, &hourly_tick);
998		1111
999	</pre>	1112	</pre>
1000	<p>Example: the same as above, but use a reschedule callback to do it:</p>	1113	<p>Example: The same as above, but use a reschedule callback to do it:</p>
1001	<pre> #include <math.h>	1114	<pre> #include <math.h>
1002		1115
1003	static ev_tstamp	1116	static ev_tstamp
1004	my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)	1117	my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)
1005	{	1118	{
…		…
1007	}	1120	}
1008		1121
1009	ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);	1122	ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);
1010		1123
1011	</pre>	1124	</pre>
1012	<p>Example: call a callback every hour, starting now:</p>	1125	<p>Example: Call a callback every hour, starting now:</p>
1013	<pre> struct ev_periodic hourly_tick;	1126	<pre> struct ev_periodic hourly_tick;
1014	ev_periodic_init (&hourly_tick, clock_cb,	1127	ev_periodic_init (&hourly_tick, clock_cb,
1015	fmod (ev_now (loop), 3600.), 3600., 0);	1128	fmod (ev_now (loop), 3600.), 3600., 0);
1016	ev_periodic_start (loop, &hourly_tick);	1129	ev_periodic_start (loop, &hourly_tick);
1017		1130
…		…
1038	<dt>ev_signal_set (ev_signal *, int signum)</dt>	1151	<dt>ev_signal_set (ev_signal *, int signum)</dt>
1039	<dd>	1152	<dd>
1040	<p>Configures the watcher to trigger on the given signal number (usually one	1153	<p>Configures the watcher to trigger on the given signal number (usually one
1041	of the <code>SIGxxx</code> constants).</p>	1154	of the <code>SIGxxx</code> constants).</p>
1042	</dd>	1155	</dd>
		1156	<dt>int signum [read-only]</dt>
		1157	<dd>
		1158	<p>The signal the watcher watches out for.</p>
		1159	</dd>
1043	</dl>	1160	</dl>
1044		1161
1045		1162
1046		1163
1047		1164
…		…
1060	at the <code>rstatus</code> member of the <code>ev_child</code> watcher structure to see	1177	at the <code>rstatus</code> member of the <code>ev_child</code> watcher structure to see
1061	the status word (use the macros from <code>sys/wait.h</code> and see your systems	1178	the status word (use the macros from <code>sys/wait.h</code> and see your systems
1062	<code>waitpid</code> documentation). The <code>rpid</code> member contains the pid of the	1179	<code>waitpid</code> documentation). The <code>rpid</code> member contains the pid of the
1063	process causing the status change.</p>	1180	process causing the status change.</p>
1064	</dd>	1181	</dd>
		1182	<dt>int pid [read-only]</dt>
		1183	<dd>
		1184	<p>The process id this watcher watches out for, or <code>0</code>, meaning any process id.</p>
		1185	</dd>
		1186	<dt>int rpid [read-write]</dt>
		1187	<dd>
		1188	<p>The process id that detected a status change.</p>
		1189	</dd>
		1190	<dt>int rstatus [read-write]</dt>
		1191	<dd>
		1192	<p>The process exit/trace status caused by <code>rpid</code> (see your systems
		1193	<code>waitpid</code> and <code>sys/wait.h</code> documentation for details).</p>
		1194	</dd>
1065	</dl>	1195	</dl>
1066	<p>Example: try to exit cleanly on SIGINT and SIGTERM.</p>	1196	<p>Example: Try to exit cleanly on SIGINT and SIGTERM.</p>
1067	<pre> static void	1197	<pre> static void
1068	sigint_cb (struct ev_loop loop, struct ev_signal w, int revents)	1198	sigint_cb (struct ev_loop loop, struct ev_signal w, int revents)
1069	{	1199	{
1070	ev_unloop (loop, EVUNLOOP_ALL);	1200	ev_unloop (loop, EVUNLOOP_ALL);
1071	}	1201	}
1072		1202
1073	struct ev_signal signal_watcher;	1203	struct ev_signal signal_watcher;
1074	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);	1204	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);
1075	ev_signal_start (loop, &sigint_cb);	1205	ev_signal_start (loop, &sigint_cb);
		1206
		1207
		1208
		1209
		1210	</pre>
		1211
		1212	</div>
		1213	<h2 id="code_ev_stat_code_did_the_file_attri"><code>ev_stat</code> - did the file attributes just change?</h2>
		1214	<div id="code_ev_stat_code_did_the_file_attri-2">
		1215	<p>This watches a filesystem path for attribute changes. That is, it calls
		1216	<code>stat</code> regularly (or when the OS says it changed) and sees if it changed
		1217	compared to the last time, invoking the callback if it did.</p>
		1218	<p>The path does not need to exist: changing from "path exists" to "path does
		1219	not exist" is a status change like any other. The condition "path does
		1220	not exist" is signified by the <code>st_nlink</code> field being zero (which is
		1221	otherwise always forced to be at least one) and all the other fields of
		1222	the stat buffer having unspecified contents.</p>
		1223	<p>Since there is no standard to do this, the portable implementation simply
		1224	calls <code>stat (2)</code> regulalry on the path to see if it changed somehow. You
		1225	can specify a recommended polling interval for this case. If you specify
		1226	a polling interval of <code>0</code> (highly recommended!) then a <i>suitable,
		1227	unspecified default</i> value will be used (which you can expect to be around
		1228	five seconds, although this might change dynamically). Libev will also
		1229	impose a minimum interval which is currently around <code>0.1</code>, but thats
		1230	usually overkill.</p>
		1231	<p>This watcher type is not meant for massive numbers of stat watchers,
		1232	as even with OS-supported change notifications, this can be
		1233	resource-intensive.</p>
		1234	<p>At the time of this writing, no specific OS backends are implemented, but
		1235	if demand increases, at least a kqueue and inotify backend will be added.</p>
		1236	<dl>
		1237	<dt>ev_stat_init (ev_stat , callback, const char path, ev_tstamp interval)</dt>
		1238	<dt>ev_stat_set (ev_stat , const char path, ev_tstamp interval)</dt>
		1239	<dd>
		1240	<p>Configures the watcher to wait for status changes of the given
		1241	<code>path</code>. The <code>interval</code> is a hint on how quickly a change is expected to
		1242	be detected and should normally be specified as <code>0</code> to let libev choose
		1243	a suitable value. The memory pointed to by <code>path</code> must point to the same
		1244	path for as long as the watcher is active.</p>
		1245	<p>The callback will be receive <code>EV_STAT</code> when a change was detected,
		1246	relative to the attributes at the time the watcher was started (or the
		1247	last change was detected).</p>
		1248	</dd>
		1249	<dt>ev_stat_stat (ev_stat *)</dt>
		1250	<dd>
		1251	<p>Updates the stat buffer immediately with new values. If you change the
		1252	watched path in your callback, you could call this fucntion to avoid
		1253	detecting this change (while introducing a race condition). Can also be
		1254	useful simply to find out the new values.</p>
		1255	</dd>
		1256	<dt>ev_statdata attr [read-only]</dt>
		1257	<dd>
		1258	<p>The most-recently detected attributes of the file. Although the type is of
		1259	<code>ev_statdata</code>, this is usually the (or one of the) <code>struct stat</code> types
		1260	suitable for your system. If the <code>st_nlink</code> member is <code>0</code>, then there
		1261	was some error while <code>stat</code>ing the file.</p>
		1262	</dd>
		1263	<dt>ev_statdata prev [read-only]</dt>
		1264	<dd>
		1265	<p>The previous attributes of the file. The callback gets invoked whenever
		1266	<code>prev</code> != <code>attr</code>.</p>
		1267	</dd>
		1268	<dt>ev_tstamp interval [read-only]</dt>
		1269	<dd>
		1270	<p>The specified interval.</p>
		1271	</dd>
		1272	<dt>const char *path [read-only]</dt>
		1273	<dd>
		1274	<p>The filesystem path that is being watched.</p>
		1275	</dd>
		1276	</dl>
		1277	<p>Example: Watch <code>/etc/passwd</code> for attribute changes.</p>
		1278	<pre> static void
		1279	passwd_cb (struct ev_loop loop, ev_stat w, int revents)
		1280	{
		1281	/* /etc/passwd changed in some way */
		1282	if (w->attr.st_nlink)
		1283	{
		1284	printf ("passwd current size %ld\n", (long)w->attr.st_size);
		1285	printf ("passwd current atime %ld\n", (long)w->attr.st_mtime);
		1286	printf ("passwd current mtime %ld\n", (long)w->attr.st_mtime);
		1287	}
		1288	else
		1289	/* you shalt not abuse printf for puts */
		1290	puts ("wow, /etc/passwd is not there, expect problems. "
		1291	"if this is windows, they already arrived\n");
		1292	}
		1293
		1294	...
		1295	ev_stat passwd;
		1296
		1297	ev_stat_init (&passwd, passwd_cb, "/etc/passwd");
		1298	ev_stat_start (loop, &passwd);
1076		1299
1077		1300
1078		1301
1079		1302
1080	</pre>	1303	</pre>
…		…
1101	<p>Initialises and configures the idle watcher - it has no parameters of any	1324	<p>Initialises and configures the idle watcher - it has no parameters of any
1102	kind. There is a <code>ev_idle_set</code> macro, but using it is utterly pointless,	1325	kind. There is a <code>ev_idle_set</code> macro, but using it is utterly pointless,
1103	believe me.</p>	1326	believe me.</p>
1104	</dd>	1327	</dd>
1105	</dl>	1328	</dl>
1106	<p>Example: dynamically allocate an <code>ev_idle</code>, start it, and in the	1329	<p>Example: Dynamically allocate an <code>ev_idle</code> watcher, start it, and in the
1107	callback, free it. Alos, use no error checking, as usual.</p>	1330	callback, free it. Also, use no error checking, as usual.</p>
1108	<pre> static void	1331	<pre> static void
1109	idle_cb (struct ev_loop loop, struct ev_idle w, int revents)	1332	idle_cb (struct ev_loop loop, struct ev_idle w, int revents)
1110	{	1333	{
1111	free (w);	1334	free (w);
1112	// now do something you wanted to do when the program has	1335	// now do something you wanted to do when the program has
…		…
1126	<h2 id="code_ev_prepare_code_and_code_ev_che"><code>ev_prepare</code> and <code>ev_check</code> - customise your event loop!</h2>	1349	<h2 id="code_ev_prepare_code_and_code_ev_che"><code>ev_prepare</code> and <code>ev_check</code> - customise your event loop!</h2>
1127	<div id="code_ev_prepare_code_and_code_ev_che-2">	1350	<div id="code_ev_prepare_code_and_code_ev_che-2">
1128	<p>Prepare and check watchers are usually (but not always) used in tandem:	1351	<p>Prepare and check watchers are usually (but not always) used in tandem:
1129	prepare watchers get invoked before the process blocks and check watchers	1352	prepare watchers get invoked before the process blocks and check watchers
1130	afterwards.</p>	1353	afterwards.</p>
		1354	<p>You <i>must not</i> call <code>ev_loop</code> or similar functions that enter
		1355	the current event loop from either <code>ev_prepare</code> or <code>ev_check</code>
		1356	watchers. Other loops than the current one are fine, however. The
		1357	rationale behind this is that you do not need to check for recursion in
		1358	those watchers, i.e. the sequence will always be <code>ev_prepare</code>, blocking,
		1359	<code>ev_check</code> so if you have one watcher of each kind they will always be
		1360	called in pairs bracketing the blocking call.</p>
1131	<p>Their main purpose is to integrate other event mechanisms into libev and	1361	<p>Their main purpose is to integrate other event mechanisms into libev and
1132	their use is somewhat advanced. This could be used, for example, to track	1362	their use is somewhat advanced. This could be used, for example, to track
1133	variable changes, implement your own watchers, integrate net-snmp or a	1363	variable changes, implement your own watchers, integrate net-snmp or a
1134	coroutine library and lots more.</p>	1364	coroutine library and lots more. They are also occasionally useful if
		1365	you cache some data and want to flush it before blocking (for example,
		1366	in X programs you might want to do an <code>XFlush ()</code> in an <code>ev_prepare</code>
		1367	watcher).</p>
1135	<p>This is done by examining in each prepare call which file descriptors need	1368	<p>This is done by examining in each prepare call which file descriptors need
1136	to be watched by the other library, registering <code>ev_io</code> watchers for	1369	to be watched by the other library, registering <code>ev_io</code> watchers for
1137	them and starting an <code>ev_timer</code> watcher for any timeouts (many libraries	1370	them and starting an <code>ev_timer</code> watcher for any timeouts (many libraries
1138	provide just this functionality). Then, in the check watcher you check for	1371	provide just this functionality). Then, in the check watcher you check for
1139	any events that occured (by checking the pending status of all watchers	1372	any events that occured (by checking the pending status of all watchers
…		…
1155	<p>Initialises and configures the prepare or check watcher - they have no	1388	<p>Initialises and configures the prepare or check watcher - they have no
1156	parameters of any kind. There are <code>ev_prepare_set</code> and <code>ev_check_set</code>	1389	parameters of any kind. There are <code>ev_prepare_set</code> and <code>ev_check_set</code>
1157	macros, but using them is utterly, utterly and completely pointless.</p>	1390	macros, but using them is utterly, utterly and completely pointless.</p>
1158	</dd>	1391	</dd>
1159	</dl>	1392	</dl>
1160	<p>Example: TODO.</p>	1393	<p>Example: To include a library such as adns, you would add IO watchers
		1394	and a timeout watcher in a prepare handler, as required by libadns, and
		1395	in a check watcher, destroy them and call into libadns. What follows is
		1396	pseudo-code only of course:</p>
		1397	<pre> static ev_io iow [nfd];
		1398	static ev_timer tw;
1161		1399
		1400	static void
		1401	io_cb (ev_loop loop, ev_io w, int revents)
		1402	{
		1403	// set the relevant poll flags
		1404	// could also call adns_processreadable etc. here
		1405	struct pollfd fd = (struct pollfd )w->data;
		1406	if (revents & EV_READ ) fd->revents \|= fd->events & POLLIN;
		1407	if (revents & EV_WRITE) fd->revents \|= fd->events & POLLOUT;
		1408	}
1162		1409
		1410	// create io watchers for each fd and a timer before blocking
		1411	static void
		1412	adns_prepare_cb (ev_loop loop, ev_prepare w, int revents)
		1413	{
		1414	int timeout = 3600000;truct pollfd fds [nfd];
		1415	// actual code will need to loop here and realloc etc.
		1416	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));
1163		1417
		1418	/* the callback is illegal, but won't be called as we stop during check */
		1419	ev_timer_init (&tw, 0, timeout * 1e-3);
		1420	ev_timer_start (loop, &tw);
1164		1421
		1422	// create on ev_io per pollfd
		1423	for (int i = 0; i < nfd; ++i)
		1424	{
		1425	ev_io_init (iow + i, io_cb, fds [i].fd,
		1426	((fds [i].events & POLLIN ? EV_READ : 0)
		1427	\| (fds [i].events & POLLOUT ? EV_WRITE : 0)));
		1428
		1429	fds [i].revents = 0;
		1430	iow [i].data = fds + i;
		1431	ev_io_start (loop, iow + i);
		1432	}
		1433	}
		1434
		1435	// stop all watchers after blocking
		1436	static void
		1437	adns_check_cb (ev_loop loop, ev_check w, int revents)
		1438	{
		1439	ev_timer_stop (loop, &tw);
		1440
		1441	for (int i = 0; i < nfd; ++i)
		1442	ev_io_stop (loop, iow + i);
		1443
		1444	adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));
		1445	}
		1446
		1447
		1448
		1449
		1450	</pre>
1165		1451
1166	</div>	1452	</div>
1167	<h2 id="code_ev_embed_code_when_one_backend_"><code>ev_embed</code> - when one backend isn't enough...</h2>	1453	<h2 id="code_ev_embed_code_when_one_backend_"><code>ev_embed</code> - when one backend isn't enough...</h2>
1168	<div id="code_ev_embed_code_when_one_backend_-2">	1454	<div id="code_ev_embed_code_when_one_backend_-2">
1169	<p>This is a rather advanced watcher type that lets you embed one event loop	1455	<p>This is a rather advanced watcher type that lets you embed one event loop
…		…
1239	<dt>ev_embed_sweep (loop, ev_embed *)</dt>	1525	<dt>ev_embed_sweep (loop, ev_embed *)</dt>
1240	<dd>	1526	<dd>
1241	<p>Make a single, non-blocking sweep over the embedded loop. This works	1527	<p>Make a single, non-blocking sweep over the embedded loop. This works
1242	similarly to <code>ev_loop (embedded_loop, EVLOOP_NONBLOCK)</code>, but in the most	1528	similarly to <code>ev_loop (embedded_loop, EVLOOP_NONBLOCK)</code>, but in the most
1243	apropriate way for embedded loops.</p>	1529	apropriate way for embedded loops.</p>
		1530	</dd>
		1531	<dt>struct ev_loop *loop [read-only]</dt>
		1532	<dd>
		1533	<p>The embedded event loop.</p>
		1534	</dd>
		1535	</dl>
		1536
		1537
		1538
		1539
		1540
		1541	</div>
		1542	<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>
		1543	<div id="code_ev_fork_code_the_audacity_to_re-2">
		1544	<p>Fork watchers are called when a <code>fork ()</code> was detected (usually because
		1545	whoever is a good citizen cared to tell libev about it by calling
		1546	<code>ev_default_fork</code> or <code>ev_loop_fork</code>). The invocation is done before the
		1547	event loop blocks next and before <code>ev_check</code> watchers are being called,
		1548	and only in the child after the fork. If whoever good citizen calling
		1549	<code>ev_default_fork</code> cheats and calls it in the wrong process, the fork
		1550	handlers will be invoked, too, of course.</p>
		1551	<dl>
		1552	<dt>ev_fork_init (ev_signal *, callback)</dt>
		1553	<dd>
		1554	<p>Initialises and configures the fork watcher - it has no parameters of any
		1555	kind. There is a <code>ev_fork_set</code> macro, but using it is utterly pointless,
		1556	believe me.</p>
1244	</dd>	1557	</dd>
1245	</dl>	1558	</dl>
1246		1559
1247		1560
1248		1561
…		…
1398	</dd>	1711	</dd>
1399	<dt>w->sweep () <code>ev::embed</code> only</dt>	1712	<dt>w->sweep () <code>ev::embed</code> only</dt>
1400	<dd>	1713	<dd>
1401	<p>Invokes <code>ev_embed_sweep</code>.</p>	1714	<p>Invokes <code>ev_embed_sweep</code>.</p>
1402	</dd>	1715	</dd>
		1716	<dt>w->update () <code>ev::stat</code> only</dt>
		1717	<dd>
		1718	<p>Invokes <code>ev_stat_stat</code>.</p>
		1719	</dd>
1403	</dl>	1720	</dl>
1404	</p>	1721	</p>
1405	</dd>	1722	</dd>
1406	</dl>	1723	</dl>
1407	<p>Example: Define a class with an IO and idle watcher, start one of them in	1724	<p>Example: Define a class with an IO and idle watcher, start one of them in
…		…
1418	: io (this, &myclass::io_cb),	1735	: io (this, &myclass::io_cb),
1419	idle (this, &myclass::idle_cb)	1736	idle (this, &myclass::idle_cb)
1420	{	1737	{
1421	io.start (fd, ev::READ);	1738	io.start (fd, ev::READ);
1422	}	1739	}
		1740
		1741
		1742
		1743
		1744	</pre>
		1745
		1746	</div>
		1747	<h1 id="MACRO_MAGIC">MACRO MAGIC</h1><p><a href="#TOP" class="toplink">Top</a></p>
		1748	<div id="MACRO_MAGIC_CONTENT">
		1749	<p>Libev can be compiled with a variety of options, the most fundemantal is
		1750	<code>EV_MULTIPLICITY</code>. This option determines wether (most) functions and
		1751	callbacks have an initial <code>struct ev_loop *</code> argument.</p>
		1752	<p>To make it easier to write programs that cope with either variant, the
		1753	following macros are defined:</p>
		1754	<dl>
		1755	<dt><code>EV_A</code>, <code>EV_A_</code></dt>
		1756	<dd>
		1757	<p>This provides the loop <i>argument</i> for functions, if one is required ("ev
		1758	loop argument"). The <code>EV_A</code> form is used when this is the sole argument,
		1759	<code>EV_A_</code> is used when other arguments are following. Example:</p>
		1760	<pre> ev_unref (EV_A);
		1761	ev_timer_add (EV_A_ watcher);
		1762	ev_loop (EV_A_ 0);
		1763
		1764	</pre>
		1765	<p>It assumes the variable <code>loop</code> of type <code>struct ev_loop *</code> is in scope,
		1766	which is often provided by the following macro.</p>
		1767	</dd>
		1768	<dt><code>EV_P</code>, <code>EV_P_</code></dt>
		1769	<dd>
		1770	<p>This provides the loop <i>parameter</i> for functions, if one is required ("ev
		1771	loop parameter"). The <code>EV_P</code> form is used when this is the sole parameter,
		1772	<code>EV_P_</code> is used when other parameters are following. Example:</p>
		1773	<pre> // this is how ev_unref is being declared
		1774	static void ev_unref (EV_P);
		1775
		1776	// this is how you can declare your typical callback
		1777	static void cb (EV_P_ ev_timer *w, int revents)
		1778
		1779	</pre>
		1780	<p>It declares a parameter <code>loop</code> of type <code>struct ev_loop *</code>, quite
		1781	suitable for use with <code>EV_A</code>.</p>
		1782	</dd>
		1783	<dt><code>EV_DEFAULT</code>, <code>EV_DEFAULT_</code></dt>
		1784	<dd>
		1785	<p>Similar to the other two macros, this gives you the value of the default
		1786	loop, if multiple loops are supported ("ev loop default").</p>
		1787	</dd>
		1788	</dl>
		1789	<p>Example: Declare and initialise a check watcher, working regardless of
		1790	wether multiple loops are supported or not.</p>
		1791	<pre> static void
		1792	check_cb (EV_P_ ev_timer *w, int revents)
		1793	{
		1794	ev_check_stop (EV_A_ w);
		1795	}
		1796
		1797	ev_check check;
		1798	ev_check_init (&check, check_cb);
		1799	ev_check_start (EV_DEFAULT_ &check);
		1800	ev_loop (EV_DEFAULT_ 0);
		1801
		1802
		1803
1423		1804
1424	</pre>	1805	</pre>
1425		1806
1426	</div>	1807	</div>
1427	<h1 id="EMBEDDING">EMBEDDING</h1><p><a href="#TOP" class="toplink">Top</a></p>	1808	<h1 id="EMBEDDING">EMBEDDING</h1><p><a href="#TOP" class="toplink">Top</a></p>
…		…
1638	will have the <code>struct ev_loop *</code> as first argument, and you can create	2019	will have the <code>struct ev_loop *</code> as first argument, and you can create
1639	additional independent event loops. Otherwise there will be no support	2020	additional independent event loops. Otherwise there will be no support
1640	for multiple event loops and there is no first event loop pointer	2021	for multiple event loops and there is no first event loop pointer
1641	argument. Instead, all functions act on the single default loop.</p>	2022	argument. Instead, all functions act on the single default loop.</p>
1642	</dd>	2023	</dd>
1643	<dt>EV_PERIODICS</dt>	2024	<dt>EV_PERIODIC_ENABLE</dt>
1644	<dd>	2025	<dd>
1645	<p>If undefined or defined to be <code>1</code>, then periodic timers are supported,	2026	<p>If undefined or defined to be <code>1</code>, then periodic timers are supported. If
1646	otherwise not. This saves a few kb of code.</p>	2027	defined to be <code>0</code>, then they are not. Disabling them saves a few kB of
		2028	code.</p>
		2029	</dd>
		2030	<dt>EV_EMBED_ENABLE</dt>
		2031	<dd>
		2032	<p>If undefined or defined to be <code>1</code>, then embed watchers are supported. If
		2033	defined to be <code>0</code>, then they are not.</p>
		2034	</dd>
		2035	<dt>EV_STAT_ENABLE</dt>
		2036	<dd>
		2037	<p>If undefined or defined to be <code>1</code>, then stat watchers are supported. If
		2038	defined to be <code>0</code>, then they are not.</p>
		2039	</dd>
		2040	<dt>EV_FORK_ENABLE</dt>
		2041	<dd>
		2042	<p>If undefined or defined to be <code>1</code>, then fork watchers are supported. If
		2043	defined to be <code>0</code>, then they are not.</p>
		2044	</dd>
		2045	<dt>EV_MINIMAL</dt>
		2046	<dd>
		2047	<p>If you need to shave off some kilobytes of code at the expense of some
		2048	speed, define this symbol to <code>1</code>. Currently only used for gcc to override
		2049	some inlining decisions, saves roughly 30% codesize of amd64.</p>
		2050	</dd>
		2051	<dt>EV_PID_HASHSIZE</dt>
		2052	<dd>
		2053	<p><code>ev_child</code> watchers use a small hash table to distribute workload by
		2054	pid. The default size is <code>16</code> (or <code>1</code> with <code>EV_MINIMAL</code>), usually more
		2055	than enough. If you need to manage thousands of children you might want to
		2056	increase this value.</p>
1647	</dd>	2057	</dd>
1648	<dt>EV_COMMON</dt>	2058	<dt>EV_COMMON</dt>
1649	<dd>	2059	<dd>
1650	<p>By default, all watchers have a <code>void *data</code> member. By redefining	2060	<p>By default, all watchers have a <code>void *data</code> member. By redefining
1651	this macro to a something else you can include more and other types of	2061	this macro to a something else you can include more and other types of
…		…
1691	</pre>	2101	</pre>
1692	<p>And a <cite>ev_cpp.C</cite> implementation file that contains libev proper and is compiled:</p>	2102	<p>And a <cite>ev_cpp.C</cite> implementation file that contains libev proper and is compiled:</p>
1693	<pre> #include "ev_cpp.h"	2103	<pre> #include "ev_cpp.h"
1694	#include "ev.c"	2104	#include "ev.c"
1695		2105
		2106
		2107
		2108
1696	</pre>	2109	</pre>
		2110
		2111	</div>
		2112	<h1 id="COMPLEXITIES">COMPLEXITIES</h1><p><a href="#TOP" class="toplink">Top</a></p>
		2113	<div id="COMPLEXITIES_CONTENT">
		2114	<p>In this section the complexities of (many of) the algorithms used inside
		2115	libev will be explained. For complexity discussions about backends see the
		2116	documentation for <code>ev_default_init</code>.</p>
		2117	<p>
		2118	<dl>
		2119	<dt>Starting and stopping timer/periodic watchers: O(log skipped_other_timers)</dt>
		2120	<dt>Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)</dt>
		2121	<dt>Starting io/check/prepare/idle/signal/child watchers: O(1)</dt>
		2122	<dt>Stopping check/prepare/idle watchers: O(1)</dt>
		2123	<dt>Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % 16))</dt>
		2124	<dt>Finding the next timer per loop iteration: O(1)</dt>
		2125	<dt>Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)</dt>
		2126	<dt>Activating one watcher: O(1)</dt>
		2127	</dl>
		2128	</p>
		2129
		2130
		2131
		2132
1697		2133
1698	</div>	2134	</div>
1699	<h1 id="AUTHOR">AUTHOR</h1><p><a href="#TOP" class="toplink">Top</a></p>	2135	<h1 id="AUTHOR">AUTHOR</h1><p><a href="#TOP" class="toplink">Top</a></p>
1700	<div id="AUTHOR_CONTENT">	2136	<div id="AUTHOR_CONTENT">
1701	<p>Marc Lehmann <libev@schmorp.de>.</p>	2137	<p>Marc Lehmann <libev@schmorp.de>.</p>

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