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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 05:58:35 2007" />	9	<meta name="created" content="Thu Nov 29 13:21:20 2007" />
10	<meta name="generator" content="Pod::Xhtml 1.57" />	10	<meta name="generator" content="Pod::Xhtml 1.57" />
11	<link rel="stylesheet" href="http://res.tst.eu/pod.css"/></head>	11	<link rel="stylesheet" href="http://res.tst.eu/pod.css"/></head>
12	<body>	12	<body>
13	<div class="pod">	13	<div class="pod">
14	<!-- INDEX START -->	14	<!-- INDEX START -->
15	<h3 id="TOP">Index</h3>	15	<h3 id="TOP">Index</h3>
16		16
17	<ul><li><a href="#NAME">NAME</a></li>	17	<ul><li><a href="#NAME">NAME</a></li>
18	<li><a href="#SYNOPSIS">SYNOPSIS</a></li>	18	<li><a href="#SYNOPSIS">SYNOPSIS</a></li>
		19	<li><a href="#EXAMPLE_PROGRAM">EXAMPLE PROGRAM</a></li>
19	<li><a href="#DESCRIPTION">DESCRIPTION</a></li>	20	<li><a href="#DESCRIPTION">DESCRIPTION</a></li>
20	<li><a href="#FEATURES">FEATURES</a></li>	21	<li><a href="#FEATURES">FEATURES</a></li>
21	<li><a href="#CONVENTIONS">CONVENTIONS</a></li>	22	<li><a href="#CONVENTIONS">CONVENTIONS</a></li>
22	<li><a href="#TIME_REPRESENTATION">TIME REPRESENTATION</a></li>	23	<li><a href="#TIME_REPRESENTATION">TIME REPRESENTATION</a></li>
23	<li><a href="#GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</a></li>	24	<li><a href="#GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</a></li>
24	<li><a href="#FUNCTIONS_CONTROLLING_THE_EVENT_LOOP">FUNCTIONS CONTROLLING THE EVENT LOOP</a></li>	25	<li><a href="#FUNCTIONS_CONTROLLING_THE_EVENT_LOOP">FUNCTIONS CONTROLLING THE EVENT LOOP</a></li>
25	<li><a href="#ANATOMY_OF_A_WATCHER">ANATOMY OF A WATCHER</a>	26	<li><a href="#ANATOMY_OF_A_WATCHER">ANATOMY OF A WATCHER</a>
		27	<ul><li><a href="#GENERIC_WATCHER_FUNCTIONS">GENERIC WATCHER FUNCTIONS</a></li>
26	<ul><li><a href="#ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH">ASSOCIATING CUSTOM DATA WITH A WATCHER</a></li>	28	<li><a href="#ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH">ASSOCIATING CUSTOM DATA WITH A WATCHER</a></li>
27	</ul>	29	</ul>
28	</li>	30	</li>
29	<li><a href="#WATCHER_TYPES">WATCHER TYPES</a>	31	<li><a href="#WATCHER_TYPES">WATCHER TYPES</a>
30	<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>
31	<li><a href="#code_ev_timer_code_relative_and_opti"><code>ev_timer</code> - relative and optionally recurring timeouts</a></li>	33	<li><a href="#code_ev_timer_code_relative_and_opti"><code>ev_timer</code> - relative and optionally repeating timeouts</a></li>
32	<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>
33	<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>
34	<li><a href="#code_ev_child_code_wait_for_pid_stat"><code>ev_child</code> - wait for pid status changes</a></li>	36	<li><a href="#code_ev_child_code_watch_out_for_pro"><code>ev_child</code> - watch out for process status changes</a></li>
		37	<li><a href="#code_ev_stat_code_did_the_file_attri"><code>ev_stat</code> - did the file attributes just change?</a></li>
35	<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>
36	<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>
37	<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>
38	</ul>	42	</ul>
39	</li>	43	</li>
40	<li><a href="#OTHER_FUNCTIONS">OTHER FUNCTIONS</a></li>	44	<li><a href="#OTHER_FUNCTIONS">OTHER FUNCTIONS</a></li>
41	<li><a href="#LIBEVENT_EMULATION">LIBEVENT EMULATION</a></li>	45	<li><a href="#LIBEVENT_EMULATION">LIBEVENT EMULATION</a></li>
42	<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>
		48	<li><a href="#EMBEDDING">EMBEDDING</a>
		49	<ul><li><a href="#FILESETS">FILESETS</a>
		50	<ul><li><a href="#CORE_EVENT_LOOP">CORE EVENT LOOP</a></li>
		51	<li><a href="#LIBEVENT_COMPATIBILITY_API">LIBEVENT COMPATIBILITY API</a></li>
		52	<li><a href="#AUTOCONF_SUPPORT">AUTOCONF SUPPORT</a></li>
		53	</ul>
		54	</li>
		55	<li><a href="#PREPROCESSOR_SYMBOLS_MACROS">PREPROCESSOR SYMBOLS/MACROS</a></li>
		56	<li><a href="#EXAMPLES">EXAMPLES</a></li>
		57	</ul>
		58	</li>
		59	<li><a href="#COMPLEXITIES">COMPLEXITIES</a></li>
43	<li><a href="#AUTHOR">AUTHOR</a>	60	<li><a href="#AUTHOR">AUTHOR</a>
44	</li>	61	</li>
45	</ul><hr />	62	</ul><hr />
46	<!-- INDEX END -->	63	<!-- INDEX END -->
47		64
48	<h1 id="NAME">NAME</h1><p><a href="#TOP" class="toplink">Top</a></p>	65	<h1 id="NAME">NAME</h1>
49	<div id="NAME_CONTENT">	66	<div id="NAME_CONTENT">
50	<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>
51		68
52	</div>	69	</div>
53	<h1 id="SYNOPSIS">SYNOPSIS</h1><p><a href="#TOP" class="toplink">Top</a></p>	70	<h1 id="SYNOPSIS">SYNOPSIS</h1>
54	<div id="SYNOPSIS_CONTENT">	71	<div id="SYNOPSIS_CONTENT">
55	<pre> #include <ev.h>	72	<pre> #include <ev.h>
56		73
57	</pre>	74	</pre>
58		75
59	</div>	76	</div>
60	<h1 id="DESCRIPTION">DESCRIPTION</h1><p><a href="#TOP" class="toplink">Top</a></p>	77	<h1 id="EXAMPLE_PROGRAM">EXAMPLE PROGRAM</h1>
		78	<div id="EXAMPLE_PROGRAM_CONTENT">
		79	<pre> #include <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	}
		118
		119	</pre>
		120
		121	</div>
		122	<h1 id="DESCRIPTION">DESCRIPTION</h1>
61	<div id="DESCRIPTION_CONTENT">	123	<div id="DESCRIPTION_CONTENT">
62	<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
63	file descriptor being readable or a timeout occuring), and it will manage	125	file descriptor being readable or a timeout occuring), and it will manage
64	these event sources and provide your program with events.</p>	126	these event sources and provide your program with events.</p>
65	<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
…		…
69	watchers</i>, which are relatively small C structures you initialise with the	131	watchers</i>, which are relatively small C structures you initialise with the
70	details of the event, and then hand it over to libev by <i>starting</i> the	132	details of the event, and then hand it over to libev by <i>starting</i> the
71	watcher.</p>	133	watcher.</p>
72		134
73	</div>	135	</div>
74	<h1 id="FEATURES">FEATURES</h1><p><a href="#TOP" class="toplink">Top</a></p>	136	<h1 id="FEATURES">FEATURES</h1>
75	<div id="FEATURES_CONTENT">	137	<div id="FEATURES_CONTENT">
76	<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
77	kqueue mechanisms for file descriptor events, relative timers, absolute	139	BSD-specific <code>kqueue</code> and the Solaris-specific event port mechanisms
78	timers with customised rescheduling, signal events, process status change	140	for file descriptor events (<code>ev_io</code>), the Linux <code>inotify</code> interface
79	events (related to SIGCHLD), and event watchers dealing with the event	141	(for <code>ev_stat</code>), relative timers (<code>ev_timer</code>), absolute timers
80	loop mechanism itself (idle, prepare and check watchers). It also is quite	142	with customised rescheduling (<code>ev_periodic</code>), synchronous signals
		143	(<code>ev_signal</code>), process status change events (<code>ev_child</code>), and event
		144	watchers 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
		146	file 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
81	fast (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
82	it to libevent for example).</p>	150	for example).</p>
83		151
84	</div>	152	</div>
85	<h1 id="CONVENTIONS">CONVENTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p>	153	<h1 id="CONVENTIONS">CONVENTIONS</h1>
86	<div id="CONVENTIONS_CONTENT">	154	<div id="CONVENTIONS_CONTENT">
87	<p>Libev is very configurable. In this manual the default configuration	155	<p>Libev is very configurable. In this manual the default configuration will
88	will be described, which supports multiple event loops. For more info	156	be described, which supports multiple event loops. For more info about
89	about various configuration options please have a look at the file	157	various configuration options please have a look at <strong>EMBED</strong> section in
90	<cite>README.embed</cite> in the libev distribution. If libev was configured without	158	this manual. If libev was configured without support for multiple event
91	support for multiple event loops, then all functions taking an initial	159	loops, then all functions taking an initial argument of name <code>loop</code>
92	argument 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>
93	will not have this argument.</p>
94		161
95	</div>	162	</div>
96	<h1 id="TIME_REPRESENTATION">TIME REPRESENTATION</h1><p><a href="#TOP" class="toplink">Top</a></p>	163	<h1 id="TIME_REPRESENTATION">TIME REPRESENTATION</h1>
97	<div id="TIME_REPRESENTATION_CONTENT">	164	<div id="TIME_REPRESENTATION_CONTENT">
98	<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
99	(fractional) number of seconds since the (POSIX) epoch (somewhere near	166	(fractional) number of seconds since the (POSIX) epoch (somewhere near
100	the beginning of 1970, details are complicated, don't ask). This type is	167	the beginning of 1970, details are complicated, don't ask). This type is
101	called <code>ev_tstamp</code>, which is what you should use too. It usually aliases	168	called <code>ev_tstamp</code>, which is what you should use too. It usually aliases
102	to the <code>double</code> type in C, and when you need to do any calculations on	169	to the <code>double</code> type in C, and when you need to do any calculations on
103	it, you should treat it as such.</p>	170	it, you should treat it as such.</p>
104		171
105
106
107
108
109	</div>	172	</div>
110	<h1 id="GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p>	173	<h1 id="GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</h1>
111	<div id="GLOBAL_FUNCTIONS_CONTENT">	174	<div id="GLOBAL_FUNCTIONS_CONTENT">
112	<p>These functions can be called anytime, even before initialising the	175	<p>These functions can be called anytime, even before initialising the
113	library in any way.</p>	176	library in any way.</p>
114	<dl>	177	<dl>
115	<dt>ev_tstamp ev_time ()</dt>	178	<dt>ev_tstamp ev_time ()</dt>
…		…
128	version of the library your program was compiled against.</p>	191	version of the library your program was compiled against.</p>
129	<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,
130	as this indicates an incompatible change. Minor versions are usually	193	as this indicates an incompatible change. Minor versions are usually
131	compatible to older versions, so a larger minor version alone is usually	194	compatible to older versions, so a larger minor version alone is usually
132	not a problem.</p>	195	not a problem.</p>
133	<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
134	version:</p>	197	version.</p>
135	<pre> assert (("libev version mismatch",	198	<pre> assert (("libev version mismatch",
136	ev_version_major () == EV_VERSION_MAJOR	199	ev_version_major () == EV_VERSION_MAJOR
137	&& ev_version_minor () >= EV_VERSION_MINOR));	200	&& ev_version_minor () >= EV_VERSION_MINOR));
138		201
139	</pre>	202	</pre>
…		…
169	recommended ones.</p>	232	recommended ones.</p>
170	<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>
171	</dd>	234	</dd>
172	<dt>ev_set_allocator (void (cb)(void *ptr, long size))</dt>	235	<dt>ev_set_allocator (void (cb)(void *ptr, long size))</dt>
173	<dd>	236	<dd>
174	<p>Sets the allocation function to use (the prototype is similar to the	237	<p>Sets the allocation function to use (the prototype is similar - the
175	realloc C function, the semantics are identical). It is used to allocate	238	semantics is identical - to the realloc C function). It is used to
176	and free memory (no surprises here). If it returns zero when memory	239	allocate and free memory (no surprises here). If it returns zero when
177	needs to be allocated, the library might abort or take some potentially	240	memory needs to be allocated, the library might abort or take some
178	destructive action. The default is your system realloc function.</p>	241	potentially destructive action. The default is your system realloc
		242	function.</p>
179	<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,
180	free some memory if it cannot allocate memory, to use a special allocator,	244	free some memory if it cannot allocate memory, to use a special allocator,
181	or even to sleep a while and retry until some memory is available.</p>	245	or even to sleep a while and retry until some memory is available.</p>
182	<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
183	retries: better than mine).</p>	247	retries).</p>
184	<pre> static void *	248	<pre> static void *
185	persistent_realloc (void *ptr, long size)	249	persistent_realloc (void *ptr, size_t size)
186	{	250	{
187	for (;;)	251	for (;;)
188	{	252	{
189	void *newptr = realloc (ptr, size);	253	void *newptr = realloc (ptr, size);
190		254
…		…
207	indicating the system call or subsystem causing the problem. If this	271	indicating the system call or subsystem causing the problem. If this
208	callback is set, then libev will expect it to remedy the sitution, no	272	callback is set, then libev will expect it to remedy the sitution, no
209	matter what, when it returns. That is, libev will generally retry the	273	matter what, when it returns. That is, libev will generally retry the
210	requested operation, or, if the condition doesn't go away, do bad stuff	274	requested operation, or, if the condition doesn't go away, do bad stuff
211	(such as abort).</p>	275	(such as abort).</p>
212	<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>
213	<pre> static void	277	<pre> static void
214	fatal_error (const char *msg)	278	fatal_error (const char *msg)
215	{	279	{
216	perror (msg);	280	perror (msg);
217	abort ();	281	abort ();
…		…
223	</pre>	287	</pre>
224	</dd>	288	</dd>
225	</dl>	289	</dl>
226		290
227	</div>	291	</div>
228	<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>
229	<div id="FUNCTIONS_CONTROLLING_THE_EVENT_LOOP-2">	293	<div id="FUNCTIONS_CONTROLLING_THE_EVENT_LOOP-2">
230	<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
231	types of such loops, the <i>default</i> loop, which supports signals and child	295	types of such loops, the <i>default</i> loop, which supports signals and child
232	events, and dynamically created loops which do not.</p>	296	events, and dynamically created loops which do not.</p>
233	<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
…		…
353	<dd>	417	<dd>
354	<p>Similar to <code>ev_default_loop</code>, but always creates a new event loop that is	418	<p>Similar to <code>ev_default_loop</code>, but always creates a new event loop that is
355	always distinct from the default loop. Unlike the default loop, it cannot	419	always distinct from the default loop. Unlike the default loop, it cannot
356	handle signal and child watchers, and attempts to do so will be greeted by	420	handle signal and child watchers, and attempts to do so will be greeted by
357	undefined behaviour (or a failed assertion if assertions are enabled).</p>	421	undefined behaviour (or a failed assertion if assertions are enabled).</p>
358	<p>Example: try to create a event loop that uses epoll and nothing else.</p>	422	<p>Example: Try to create a event loop that uses epoll and nothing else.</p>
359	<pre> struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL \| EVFLAG_NOENV);	423	<pre> struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL \| EVFLAG_NOENV);
360	if (!epoller)	424	if (!epoller)
361	fatal ("no epoll found here, maybe it hides under your chair");	425	fatal ("no epoll found here, maybe it hides under your chair");
362		426
363	</pre>	427	</pre>
364	</dd>	428	</dd>
365	<dt>ev_default_destroy ()</dt>	429	<dt>ev_default_destroy ()</dt>
366	<dd>	430	<dd>
367	<p>Destroys the default loop again (frees all memory and kernel state	431	<p>Destroys the default loop again (frees all memory and kernel state
368	etc.). This stops all registered event watchers (by not touching them in	432	etc.). None of the active event watchers will be stopped in the normal
369	any way whatsoever, although you cannot rely on this :).</p>	433	sense, so e.g. <code>ev_is_active</code> might still return true. It is your
		434	responsibility to either stop all watchers cleanly yoursef <i>before</i>
		435	calling this function, or cope with the fact afterwards (which is usually
		436	the easiest thing, youc na just ignore the watchers and/or <code>free ()</code> them
		437	for example).</p>
370	</dd>	438	</dd>
371	<dt>ev_loop_destroy (loop)</dt>	439	<dt>ev_loop_destroy (loop)</dt>
372	<dd>	440	<dd>
373	<p>Like <code>ev_default_destroy</code>, but destroys an event loop created by an	441	<p>Like <code>ev_default_destroy</code>, but destroys an event loop created by an
374	earlier call to <code>ev_loop_new</code>.</p>	442	earlier call to <code>ev_loop_new</code>.</p>
…		…
452	be handled here by queueing them when their watcher gets executed.	520	be handled here by queueing them when their watcher gets executed.
453	- If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK	521	- If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK
454	were used, return, otherwise continue with step *.	522	were used, return, otherwise continue with step *.
455		523
456	</pre>	524	</pre>
457	<p>Example: queue some jobs and then loop until no events are outsanding	525	<p>Example: Queue some jobs and then loop until no events are outsanding
458	anymore.</p>	526	anymore.</p>
459	<pre> ... queue jobs here, make sure they register event watchers as long	527	<pre> ... queue jobs here, make sure they register event watchers as long
460	... as they still have work to do (even an idle watcher will do..)	528	... as they still have work to do (even an idle watcher will do..)
461	ev_loop (my_loop, 0);	529	ev_loop (my_loop, 0);
462	... jobs done. yeah!	530	... jobs done. yeah!
…		…
481	example, libev itself uses this for its internal signal pipe: It is not	549	example, libev itself uses this for its internal signal pipe: It is not
482	visible to the libev user and should not keep <code>ev_loop</code> from exiting if	550	visible to the libev user and should not keep <code>ev_loop</code> from exiting if
483	no event watchers registered by it are active. It is also an excellent	551	no event watchers registered by it are active. It is also an excellent
484	way to do this for generic recurring timers or from within third-party	552	way to do this for generic recurring timers or from within third-party
485	libraries. Just remember to <i>unref after start</i> and <i>ref before stop</i>.</p>	553	libraries. Just remember to <i>unref after start</i> and <i>ref before stop</i>.</p>
486	<p>Example: create a signal watcher, but keep it from keeping <code>ev_loop</code>	554	<p>Example: Create a signal watcher, but keep it from keeping <code>ev_loop</code>
487	running when nothing else is active.</p>	555	running when nothing else is active.</p>
488	<pre> struct dv_signal exitsig;	556	<pre> struct ev_signal exitsig;
489	ev_signal_init (&exitsig, sig_cb, SIGINT);	557	ev_signal_init (&exitsig, sig_cb, SIGINT);
490	ev_signal_start (myloop, &exitsig);	558	ev_signal_start (loop, &exitsig);
491	evf_unref (myloop);	559	evf_unref (loop);
492		560
493	</pre>	561	</pre>
494	<p>Example: for some weird reason, unregister the above signal handler again.</p>	562	<p>Example: For some weird reason, unregister the above signal handler again.</p>
495	<pre> ev_ref (myloop);	563	<pre> ev_ref (loop);
496	ev_signal_stop (myloop, &exitsig);	564	ev_signal_stop (loop, &exitsig);
497		565
498	</pre>	566	</pre>
499	</dd>	567	</dd>
500	</dl>	568	</dl>
501		569
		570
		571
		572
		573
502	</div>	574	</div>
503	<h1 id="ANATOMY_OF_A_WATCHER">ANATOMY OF A WATCHER</h1><p><a href="#TOP" class="toplink">Top</a></p>	575	<h1 id="ANATOMY_OF_A_WATCHER">ANATOMY OF A WATCHER</h1>
504	<div id="ANATOMY_OF_A_WATCHER_CONTENT">	576	<div id="ANATOMY_OF_A_WATCHER_CONTENT">
505	<p>A watcher is a structure that you create and register to record your	577	<p>A watcher is a structure that you create and register to record your
506	interest in some event. For instance, if you want to wait for STDIN to	578	interest in some event. For instance, if you want to wait for STDIN to
507	become readable, you would create an <code>ev_io</code> watcher for that:</p>	579	become readable, you would create an <code>ev_io</code> watcher for that:</p>
508	<pre> static void my_cb (struct ev_loop loop, struct ev_io w, int revents)	580	<pre> static void my_cb (struct ev_loop loop, struct ev_io w, int revents)
…		…
535	with a watcher-specific start function (<code>ev_<type>_start (loop, watcher	607	with a watcher-specific start function (<code>ev_<type>_start (loop, watcher
536	*)</code>), and you can stop watching for events at any time by calling the	608	*)</code>), and you can stop watching for events at any time by calling the
537	corresponding stop function (<code>ev_<type>_stop (loop, watcher *)</code>.</p>	609	corresponding stop function (<code>ev_<type>_stop (loop, watcher *)</code>.</p>
538	<p>As long as your watcher is active (has been started but not stopped) you	610	<p>As long as your watcher is active (has been started but not stopped) you
539	must not touch the values stored in it. Most specifically you must never	611	must not touch the values stored in it. Most specifically you must never
540	reinitialise it or call its set macro.</p>	612	reinitialise it or call its <code>set</code> macro.</p>
541	<p>You can check whether an event is active by calling the <code>ev_is_active
542	(watcher *)</code> macro. To see whether an event is outstanding (but the
543	callback for it has not been called yet) you can use the <code>ev_is_pending
544	(watcher *)</code> macro.</p>
545	<p>Each and every callback receives the event loop pointer as first, the	613	<p>Each and every callback receives the event loop pointer as first, the
546	registered watcher structure as second, and a bitset of received events as	614	registered watcher structure as second, and a bitset of received events as
547	third argument.</p>	615	third argument.</p>
548	<p>The received events usually include a single bit per event type received	616	<p>The received events usually include a single bit per event type received
549	(you can receive multiple events at the same time). The possible bit masks	617	(you can receive multiple events at the same time). The possible bit masks
…		…
569	</dd>	637	</dd>
570	<dt><code>EV_CHILD</code></dt>	638	<dt><code>EV_CHILD</code></dt>
571	<dd>	639	<dd>
572	<p>The pid specified in the <code>ev_child</code> watcher has received a status change.</p>	640	<p>The pid specified in the <code>ev_child</code> watcher has received a status change.</p>
573	</dd>	641	</dd>
		642	<dt><code>EV_STAT</code></dt>
		643	<dd>
		644	<p>The path specified in the <code>ev_stat</code> watcher changed its attributes somehow.</p>
		645	</dd>
574	<dt><code>EV_IDLE</code></dt>	646	<dt><code>EV_IDLE</code></dt>
575	<dd>	647	<dd>
576	<p>The <code>ev_idle</code> watcher has determined that you have nothing better to do.</p>	648	<p>The <code>ev_idle</code> watcher has determined that you have nothing better to do.</p>
577	</dd>	649	</dd>
578	<dt><code>EV_PREPARE</code></dt>	650	<dt><code>EV_PREPARE</code></dt>
…		…
583	<code>ev_loop</code> has gathered them, but before it invokes any callbacks for any	655	<code>ev_loop</code> has gathered them, but before it invokes any callbacks for any
584	received events. Callbacks of both watcher types can start and stop as	656	received events. Callbacks of both watcher types can start and stop as
585	many watchers as they want, and all of them will be taken into account	657	many watchers as they want, and all of them will be taken into account
586	(for example, a <code>ev_prepare</code> watcher might start an idle watcher to keep	658	(for example, a <code>ev_prepare</code> watcher might start an idle watcher to keep
587	<code>ev_loop</code> from blocking).</p>	659	<code>ev_loop</code> from blocking).</p>
		660	</dd>
		661	<dt><code>EV_EMBED</code></dt>
		662	<dd>
		663	<p>The embedded event loop specified in the <code>ev_embed</code> watcher needs attention.</p>
		664	</dd>
		665	<dt><code>EV_FORK</code></dt>
		666	<dd>
		667	<p>The event loop has been resumed in the child process after fork (see
		668	<code>ev_fork</code>).</p>
588	</dd>	669	</dd>
589	<dt><code>EV_ERROR</code></dt>	670	<dt><code>EV_ERROR</code></dt>
590	<dd>	671	<dd>
591	<p>An unspecified error has occured, the watcher has been stopped. This might	672	<p>An unspecified error has occured, the watcher has been stopped. This might
592	happen because the watcher could not be properly started because libev	673	happen because the watcher could not be properly started because libev
…		…
600	programs, though, so beware.</p>	681	programs, though, so beware.</p>
601	</dd>	682	</dd>
602	</dl>	683	</dl>
603		684
604	</div>	685	</div>
		686	<h2 id="GENERIC_WATCHER_FUNCTIONS">GENERIC WATCHER FUNCTIONS</h2>
		687	<div id="GENERIC_WATCHER_FUNCTIONS_CONTENT">
		688	<p>In the following description, <code>TYPE</code> stands for the watcher type,
		689	e.g. <code>timer</code> for <code>ev_timer</code> watchers and <code>io</code> for <code>ev_io</code> watchers.</p>
		690	<dl>
		691	<dt><code>ev_init</code> (ev_TYPE *watcher, callback)</dt>
		692	<dd>
		693	<p>This macro initialises the generic portion of a watcher. The contents
		694	of the watcher object can be arbitrary (so <code>malloc</code> will do). Only
		695	the generic parts of the watcher are initialised, you <i>need</i> to call
		696	the type-specific <code>ev_TYPE_set</code> macro afterwards to initialise the
		697	type-specific parts. For each type there is also a <code>ev_TYPE_init</code> macro
		698	which rolls both calls into one.</p>
		699	<p>You can reinitialise a watcher at any time as long as it has been stopped
		700	(or never started) and there are no pending events outstanding.</p>
		701	<p>The callback is always of type <code>void ()(ev_loop loop, ev_TYPE *watcher,
		702	int revents)</code>.</p>
		703	</dd>
		704	<dt><code>ev_TYPE_set</code> (ev_TYPE *, [args])</dt>
		705	<dd>
		706	<p>This macro initialises the type-specific parts of a watcher. You need to
		707	call <code>ev_init</code> at least once before you call this macro, but you can
		708	call <code>ev_TYPE_set</code> any number of times. You must not, however, call this
		709	macro on a watcher that is active (it can be pending, however, which is a
		710	difference to the <code>ev_init</code> macro).</p>
		711	<p>Although some watcher types do not have type-specific arguments
		712	(e.g. <code>ev_prepare</code>) you still need to call its <code>set</code> macro.</p>
		713	</dd>
		714	<dt><code>ev_TYPE_init</code> (ev_TYPE *watcher, callback, [args])</dt>
		715	<dd>
		716	<p>This convinience macro rolls both <code>ev_init</code> and <code>ev_TYPE_set</code> macro
		717	calls into a single call. This is the most convinient method to initialise
		718	a watcher. The same limitations apply, of course.</p>
		719	</dd>
		720	<dt><code>ev_TYPE_start</code> (loop , ev_TYPE watcher)</dt>
		721	<dd>
		722	<p>Starts (activates) the given watcher. Only active watchers will receive
		723	events. If the watcher is already active nothing will happen.</p>
		724	</dd>
		725	<dt><code>ev_TYPE_stop</code> (loop , ev_TYPE watcher)</dt>
		726	<dd>
		727	<p>Stops the given watcher again (if active) and clears the pending
		728	status. It is possible that stopped watchers are pending (for example,
		729	non-repeating timers are being stopped when they become pending), but
		730	<code>ev_TYPE_stop</code> ensures that the watcher is neither active nor pending. If
		731	you want to free or reuse the memory used by the watcher it is therefore a
		732	good idea to always call its <code>ev_TYPE_stop</code> function.</p>
		733	</dd>
		734	<dt>bool ev_is_active (ev_TYPE *watcher)</dt>
		735	<dd>
		736	<p>Returns a true value iff the watcher is active (i.e. it has been started
		737	and not yet been stopped). As long as a watcher is active you must not modify
		738	it.</p>
		739	</dd>
		740	<dt>bool ev_is_pending (ev_TYPE *watcher)</dt>
		741	<dd>
		742	<p>Returns a true value iff the watcher is pending, (i.e. it has outstanding
		743	events but its callback has not yet been invoked). As long as a watcher
		744	is pending (but not active) you must not call an init function on it (but
		745	<code>ev_TYPE_set</code> is safe) and you must make sure the watcher is available to
		746	libev (e.g. you cnanot <code>free ()</code> it).</p>
		747	</dd>
		748	<dt>callback ev_cb (ev_TYPE *watcher)</dt>
		749	<dd>
		750	<p>Returns the callback currently set on the watcher.</p>
		751	</dd>
		752	<dt>ev_cb_set (ev_TYPE *watcher, callback)</dt>
		753	<dd>
		754	<p>Change the callback. You can change the callback at virtually any time
		755	(modulo threads).</p>
		756	</dd>
		757	</dl>
		758
		759
		760
		761
		762
		763	</div>
605	<h2 id="ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH">ASSOCIATING CUSTOM DATA WITH A WATCHER</h2>	764	<h2 id="ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH">ASSOCIATING CUSTOM DATA WITH A WATCHER</h2>
606	<div id="ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH-2">	765	<div id="ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH-2">
607	<p>Each watcher has, by default, a member <code>void *data</code> that you can change	766	<p>Each watcher has, by default, a member <code>void *data</code> that you can change
608	and read at any time, libev will completely ignore it. This can be used	767	and read at any time, libev will completely ignore it. This can be used
609	to associate arbitrary data with your watcher. If you need more data and	768	to associate arbitrary data with your watcher. If you need more data and
…		…
626	struct my_io w = (struct my_io )w_;	785	struct my_io w = (struct my_io )w_;
627	...	786	...
628	}	787	}
629		788
630	</pre>	789	</pre>
631	<p>More interesting and less C-conformant ways of catsing your callback type	790	<p>More interesting and less C-conformant ways of casting your callback type
632	have been omitted....</p>	791	instead have been omitted.</p>
		792	<p>Another common scenario is having some data structure with multiple
		793	watchers:</p>
		794	<pre> struct my_biggy
		795	{
		796	int some_data;
		797	ev_timer t1;
		798	ev_timer t2;
		799	}
633		800
		801	</pre>
		802	<p>In this case getting the pointer to <code>my_biggy</code> is a bit more complicated,
		803	you need to use <code>offsetof</code>:</p>
		804	<pre> #include <stddef.h>
634		805
		806	static void
		807	t1_cb (EV_P_ struct ev_timer *w, int revents)
		808	{
		809	struct my_biggy big = (struct my_biggy *
		810	(((char *)w) - offsetof (struct my_biggy, t1));
		811	}
635		812
		813	static void
		814	t2_cb (EV_P_ struct ev_timer *w, int revents)
		815	{
		816	struct my_biggy big = (struct my_biggy *
		817	(((char *)w) - offsetof (struct my_biggy, t2));
		818	}
636		819
637		820
		821
		822
		823	</pre>
		824
638	</div>	825	</div>
639	<h1 id="WATCHER_TYPES">WATCHER TYPES</h1><p><a href="#TOP" class="toplink">Top</a></p>	826	<h1 id="WATCHER_TYPES">WATCHER TYPES</h1>
640	<div id="WATCHER_TYPES_CONTENT">	827	<div id="WATCHER_TYPES_CONTENT">
641	<p>This section describes each watcher in detail, but will not repeat	828	<p>This section describes each watcher in detail, but will not repeat
642	information given in the last section.</p>	829	information given in the last section. Any initialisation/set macros,
		830	functions and members specific to the watcher type are explained.</p>
		831	<p>Members are additionally marked with either <i>[read-only]</i>, meaning that,
		832	while the watcher is active, you can look at the member and expect some
		833	sensible content, but you must not modify it (you can modify it while the
		834	watcher is stopped to your hearts content), or <i>[read-write]</i>, which
		835	means you can expect it to have some sensible content while the watcher
		836	is active, but you can also modify it. Modifying it may not do something
		837	sensible or take immediate effect (or do anything at all), but libev will
		838	not crash or malfunction in any way.</p>
643		839
644		840
645		841
646		842
647		843
648	</div>	844	</div>
649	<h2 id="code_ev_io_code_is_this_file_descrip"><code>ev_io</code> - is this file descriptor readable or writable</h2>	845	<h2 id="code_ev_io_code_is_this_file_descrip"><code>ev_io</code> - is this file descriptor readable or writable?</h2>
650	<div id="code_ev_io_code_is_this_file_descrip-2">	846	<div id="code_ev_io_code_is_this_file_descrip-2">
651	<p>I/O watchers check whether a file descriptor is readable or writable	847	<p>I/O watchers check whether a file descriptor is readable or writable
652	in each iteration of the event loop (This behaviour is called	848	in each iteration of the event loop, or, more precisely, when reading
653	level-triggering because you keep receiving events as long as the	849	would not block the process and writing would at least be able to write
654	condition persists. Remember you can stop the watcher if you don't want to	850	some data. This behaviour is called level-triggering because you keep
655	act on the event and neither want to receive future events).</p>	851	receiving events as long as the condition persists. Remember you can stop
		852	the watcher if you don't want to act on the event and neither want to
		853	receive future events.</p>
656	<p>In general you can register as many read and/or write event watchers per	854	<p>In general you can register as many read and/or write event watchers per
657	fd as you want (as long as you don't confuse yourself). Setting all file	855	fd as you want (as long as you don't confuse yourself). Setting all file
658	descriptors to non-blocking mode is also usually a good idea (but not	856	descriptors to non-blocking mode is also usually a good idea (but not
659	required if you know what you are doing).</p>	857	required if you know what you are doing).</p>
660	<p>You have to be careful with dup'ed file descriptors, though. Some backends	858	<p>You have to be careful with dup'ed file descriptors, though. Some backends
661	(the linux epoll backend is a notable example) cannot handle dup'ed file	859	(the linux epoll backend is a notable example) cannot handle dup'ed file
662	descriptors correctly if you register interest in two or more fds pointing	860	descriptors correctly if you register interest in two or more fds pointing
663	to the same underlying file/socket etc. description (that is, they share	861	to the same underlying file/socket/etc. description (that is, they share
664	the same underlying "file open").</p>	862	the same underlying "file open").</p>
665	<p>If you must do this, then force the use of a known-to-be-good backend	863	<p>If you must do this, then force the use of a known-to-be-good backend
666	(at the time of this writing, this includes only <code>EVBACKEND_SELECT</code> and	864	(at the time of this writing, this includes only <code>EVBACKEND_SELECT</code> and
667	<code>EVBACKEND_POLL</code>).</p>	865	<code>EVBACKEND_POLL</code>).</p>
		866	<p>Another thing you have to watch out for is that it is quite easy to
		867	receive "spurious" readyness notifications, that is your callback might
		868	be called with <code>EV_READ</code> but a subsequent <code>read</code>(2) will actually block
		869	because there is no data. Not only are some backends known to create a
		870	lot of those (for example solaris ports), it is very easy to get into
		871	this situation even with a relatively standard program structure. Thus
		872	it is best to always use non-blocking I/O: An extra <code>read</code>(2) returning
		873	<code>EAGAIN</code> is far preferable to a program hanging until some data arrives.</p>
		874	<p>If you cannot run the fd in non-blocking mode (for example you should not
		875	play around with an Xlib connection), then you have to seperately re-test
		876	wether a file descriptor is really ready with a known-to-be good interface
		877	such as poll (fortunately in our Xlib example, Xlib already does this on
		878	its own, so its quite safe to use).</p>
668	<dl>	879	<dl>
669	<dt>ev_io_init (ev_io *, callback, int fd, int events)</dt>	880	<dt>ev_io_init (ev_io *, callback, int fd, int events)</dt>
670	<dt>ev_io_set (ev_io *, int fd, int events)</dt>	881	<dt>ev_io_set (ev_io *, int fd, int events)</dt>
671	<dd>	882	<dd>
672	<p>Configures an <code>ev_io</code> watcher. The fd is the file descriptor to rceeive	883	<p>Configures an <code>ev_io</code> watcher. The <code>fd</code> is the file descriptor to
673	events for and events is either <code>EV_READ</code>, <code>EV_WRITE</code> or <code>EV_READ \|	884	rceeive events for and events is either <code>EV_READ</code>, <code>EV_WRITE</code> or
674	EV_WRITE</code> to receive the given events.</p>	885	<code>EV_READ \| EV_WRITE</code> to receive the given events.</p>
675	<p>Please note that most of the more scalable backend mechanisms (for example	886	</dd>
676	epoll and solaris ports) can result in spurious readyness notifications	887	<dt>int fd [read-only]</dt>
677	for file descriptors, so you practically need to use non-blocking I/O (and	888	<dd>
678	treat callback invocation as hint only), or retest separately with a safe	889	<p>The file descriptor being watched.</p>
679	interface before doing I/O (XLib can do this), or force the use of either	890	</dd>
680	<code>EVBACKEND_SELECT</code> or <code>EVBACKEND_POLL</code>, which don't suffer from this	891	<dt>int events [read-only]</dt>
681	problem. Also note that it is quite easy to have your callback invoked	892	<dd>
682	when the readyness condition is no longer valid even when employing	893	<p>The events being watched.</p>
683	typical ways of handling events, so its a good idea to use non-blocking
684	I/O unconditionally.</p>
685	</dd>	894	</dd>
686	</dl>	895	</dl>
687	<p>Example: call <code>stdin_readable_cb</code> when STDIN_FILENO has become, well	896	<p>Example: Call <code>stdin_readable_cb</code> when STDIN_FILENO has become, well
688	readable, but only once. Since it is likely line-buffered, you could	897	readable, but only once. Since it is likely line-buffered, you could
689	attempt to read a whole line in the callback:</p>	898	attempt to read a whole line in the callback.</p>
690	<pre> static void	899	<pre> static void
691	stdin_readable_cb (struct ev_loop loop, struct ev_io w, int revents)	900	stdin_readable_cb (struct ev_loop loop, struct ev_io w, int revents)
692	{	901	{
693	ev_io_stop (loop, w);	902	ev_io_stop (loop, w);
694	.. read from stdin here (or from w->fd) and haqndle any I/O errors	903	.. read from stdin here (or from w->fd) and haqndle any I/O errors
…		…
705		914
706		915
707	</pre>	916	</pre>
708		917
709	</div>	918	</div>
710	<h2 id="code_ev_timer_code_relative_and_opti"><code>ev_timer</code> - relative and optionally recurring timeouts</h2>	919	<h2 id="code_ev_timer_code_relative_and_opti"><code>ev_timer</code> - relative and optionally repeating timeouts</h2>
711	<div id="code_ev_timer_code_relative_and_opti-2">	920	<div id="code_ev_timer_code_relative_and_opti-2">
712	<p>Timer watchers are simple relative timers that generate an event after a	921	<p>Timer watchers are simple relative timers that generate an event after a
713	given time, and optionally repeating in regular intervals after that.</p>	922	given time, and optionally repeating in regular intervals after that.</p>
714	<p>The timers are based on real time, that is, if you register an event that	923	<p>The timers are based on real time, that is, if you register an event that
715	times out after an hour and you reset your system clock to last years	924	times out after an hour and you reset your system clock to last years
…		…
743	</dd>	952	</dd>
744	<dt>ev_timer_again (loop)</dt>	953	<dt>ev_timer_again (loop)</dt>
745	<dd>	954	<dd>
746	<p>This will act as if the timer timed out and restart it again if it is	955	<p>This will act as if the timer timed out and restart it again if it is
747	repeating. The exact semantics are:</p>	956	repeating. The exact semantics are:</p>
		957	<p>If the timer is pending, its pending status is cleared.</p>
748	<p>If the timer is started but nonrepeating, stop it.</p>	958	<p>If the timer is started but nonrepeating, stop it (as if it timed out).</p>
749	<p>If the timer is repeating, either start it if necessary (with the repeat	959	<p>If the timer is repeating, either start it if necessary (with the
750	value), or reset the running timer to the repeat value.</p>	960	<code>repeat</code> value), or reset the running timer to the <code>repeat</code> value.</p>
751	<p>This sounds a bit complicated, but here is a useful and typical	961	<p>This sounds a bit complicated, but here is a useful and typical
752	example: Imagine you have a tcp connection and you want a so-called idle	962	example: Imagine you have a tcp connection and you want a so-called idle
753	timeout, that is, you want to be called when there have been, say, 60	963	timeout, that is, you want to be called when there have been, say, 60
754	seconds of inactivity on the socket. The easiest way to do this is to	964	seconds of inactivity on the socket. The easiest way to do this is to
755	configure an <code>ev_timer</code> with after=repeat=60 and calling ev_timer_again each	965	configure an <code>ev_timer</code> with a <code>repeat</code> value of <code>60</code> and then call
756	time you successfully read or write some data. If you go into an idle	966	<code>ev_timer_again</code> each time you successfully read or write some data. If
757	state where you do not expect data to travel on the socket, you can stop	967	you go into an idle state where you do not expect data to travel on the
		968	socket, you can <code>ev_timer_stop</code> the timer, and <code>ev_timer_again</code> will
758	the timer, and again will automatically restart it if need be.</p>	969	automatically restart it if need be.</p>
		970	<p>That means you can ignore the <code>after</code> value and <code>ev_timer_start</code>
		971	altogether and only ever use the <code>repeat</code> value and <code>ev_timer_again</code>:</p>
		972	<pre> ev_timer_init (timer, callback, 0., 5.);
		973	ev_timer_again (loop, timer);
		974	...
		975	timer->again = 17.;
		976	ev_timer_again (loop, timer);
		977	...
		978	timer->again = 10.;
		979	ev_timer_again (loop, timer);
		980
		981	</pre>
		982	<p>This is more slightly efficient then stopping/starting the timer each time
		983	you want to modify its timeout value.</p>
		984	</dd>
		985	<dt>ev_tstamp repeat [read-write]</dt>
		986	<dd>
		987	<p>The current <code>repeat</code> value. Will be used each time the watcher times out
		988	or <code>ev_timer_again</code> is called and determines the next timeout (if any),
		989	which is also when any modifications are taken into account.</p>
759	</dd>	990	</dd>
760	</dl>	991	</dl>
761	<p>Example: create a timer that fires after 60 seconds.</p>	992	<p>Example: Create a timer that fires after 60 seconds.</p>
762	<pre> static void	993	<pre> static void
763	one_minute_cb (struct ev_loop loop, struct ev_timer w, int revents)	994	one_minute_cb (struct ev_loop loop, struct ev_timer w, int revents)
764	{	995	{
765	.. one minute over, w is actually stopped right here	996	.. one minute over, w is actually stopped right here
766	}	997	}
…		…
768	struct ev_timer mytimer;	999	struct ev_timer mytimer;
769	ev_timer_init (&mytimer, one_minute_cb, 60., 0.);	1000	ev_timer_init (&mytimer, one_minute_cb, 60., 0.);
770	ev_timer_start (loop, &mytimer);	1001	ev_timer_start (loop, &mytimer);
771		1002
772	</pre>	1003	</pre>
773	<p>Example: create a timeout timer that times out after 10 seconds of	1004	<p>Example: Create a timeout timer that times out after 10 seconds of
774	inactivity.</p>	1005	inactivity.</p>
775	<pre> static void	1006	<pre> static void
776	timeout_cb (struct ev_loop loop, struct ev_timer w, int revents)	1007	timeout_cb (struct ev_loop loop, struct ev_timer w, int revents)
777	{	1008	{
778	.. ten seconds without any activity	1009	.. ten seconds without any activity
…		…
791		1022
792		1023
793	</pre>	1024	</pre>
794		1025
795	</div>	1026	</div>
796	<h2 id="code_ev_periodic_code_to_cron_or_not"><code>ev_periodic</code> - to cron or not to cron</h2>	1027	<h2 id="code_ev_periodic_code_to_cron_or_not"><code>ev_periodic</code> - to cron or not to cron?</h2>
797	<div id="code_ev_periodic_code_to_cron_or_not-2">	1028	<div id="code_ev_periodic_code_to_cron_or_not-2">
798	<p>Periodic watchers are also timers of a kind, but they are very versatile	1029	<p>Periodic watchers are also timers of a kind, but they are very versatile
799	(and unfortunately a bit complex).</p>	1030	(and unfortunately a bit complex).</p>
800	<p>Unlike <code>ev_timer</code>'s, they are not based on real time (or relative time)	1031	<p>Unlike <code>ev_timer</code>'s, they are not based on real time (or relative time)
801	but on wallclock time (absolute time). You can tell a periodic watcher	1032	but on wallclock time (absolute time). You can tell a periodic watcher
802	to trigger "at" some specific point in time. For example, if you tell a	1033	to trigger "at" some specific point in time. For example, if you tell a
803	periodic watcher to trigger in 10 seconds (by specifiying e.g. c<ev_now ()	1034	periodic watcher to trigger in 10 seconds (by specifiying e.g. <code>ev_now ()
804	+ 10.>) and then reset your system clock to the last year, then it will	1035	+ 10.</code>) and then reset your system clock to the last year, then it will
805	take a year to trigger the event (unlike an <code>ev_timer</code>, which would trigger	1036	take a year to trigger the event (unlike an <code>ev_timer</code>, which would trigger
806	roughly 10 seconds later and of course not if you reset your system time	1037	roughly 10 seconds later and of course not if you reset your system time
807	again).</p>	1038	again).</p>
808	<p>They can also be used to implement vastly more complex timers, such as	1039	<p>They can also be used to implement vastly more complex timers, such as
809	triggering an event on eahc midnight, local time.</p>	1040	triggering an event on eahc midnight, local time.</p>
…		…
881	<p>Simply stops and restarts the periodic watcher again. This is only useful	1112	<p>Simply stops and restarts the periodic watcher again. This is only useful
882	when you changed some parameters or the reschedule callback would return	1113	when you changed some parameters or the reschedule callback would return
883	a different time than the last time it was called (e.g. in a crond like	1114	a different time than the last time it was called (e.g. in a crond like
884	program when the crontabs have changed).</p>	1115	program when the crontabs have changed).</p>
885	</dd>	1116	</dd>
		1117	<dt>ev_tstamp interval [read-write]</dt>
		1118	<dd>
		1119	<p>The current interval value. Can be modified any time, but changes only
		1120	take effect when the periodic timer fires or <code>ev_periodic_again</code> is being
		1121	called.</p>
		1122	</dd>
		1123	<dt>ev_tstamp (reschedule_cb)(struct ev_periodic w, ev_tstamp now) [read-write]</dt>
		1124	<dd>
		1125	<p>The current reschedule callback, or <code>0</code>, if this functionality is
		1126	switched off. Can be changed any time, but changes only take effect when
		1127	the periodic timer fires or <code>ev_periodic_again</code> is being called.</p>
		1128	</dd>
886	</dl>	1129	</dl>
887	<p>Example: call a callback every hour, or, more precisely, whenever the	1130	<p>Example: Call a callback every hour, or, more precisely, whenever the
888	system clock is divisible by 3600. The callback invocation times have	1131	system clock is divisible by 3600. The callback invocation times have
889	potentially a lot of jittering, but good long-term stability.</p>	1132	potentially a lot of jittering, but good long-term stability.</p>
890	<pre> static void	1133	<pre> static void
891	clock_cb (struct ev_loop loop, struct ev_io w, int revents)	1134	clock_cb (struct ev_loop loop, struct ev_io w, int revents)
892	{	1135	{
…		…
896	struct ev_periodic hourly_tick;	1139	struct ev_periodic hourly_tick;
897	ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);	1140	ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);
898	ev_periodic_start (loop, &hourly_tick);	1141	ev_periodic_start (loop, &hourly_tick);
899		1142
900	</pre>	1143	</pre>
901	<p>Example: the same as above, but use a reschedule callback to do it:</p>	1144	<p>Example: The same as above, but use a reschedule callback to do it:</p>
902	<pre> #include <math.h>	1145	<pre> #include <math.h>
903		1146
904	static ev_tstamp	1147	static ev_tstamp
905	my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)	1148	my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)
906	{	1149	{
…		…
908	}	1151	}
909		1152
910	ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);	1153	ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);
911		1154
912	</pre>	1155	</pre>
913	<p>Example: call a callback every hour, starting now:</p>	1156	<p>Example: Call a callback every hour, starting now:</p>
914	<pre> struct ev_periodic hourly_tick;	1157	<pre> struct ev_periodic hourly_tick;
915	ev_periodic_init (&hourly_tick, clock_cb,	1158	ev_periodic_init (&hourly_tick, clock_cb,
916	fmod (ev_now (loop), 3600.), 3600., 0);	1159	fmod (ev_now (loop), 3600.), 3600., 0);
917	ev_periodic_start (loop, &hourly_tick);	1160	ev_periodic_start (loop, &hourly_tick);
918		1161
…		…
920		1163
921		1164
922	</pre>	1165	</pre>
923		1166
924	</div>	1167	</div>
925	<h2 id="code_ev_signal_code_signal_me_when_a"><code>ev_signal</code> - signal me when a signal gets signalled</h2>	1168	<h2 id="code_ev_signal_code_signal_me_when_a"><code>ev_signal</code> - signal me when a signal gets signalled!</h2>
926	<div id="code_ev_signal_code_signal_me_when_a-2">	1169	<div id="code_ev_signal_code_signal_me_when_a-2">
927	<p>Signal watchers will trigger an event when the process receives a specific	1170	<p>Signal watchers will trigger an event when the process receives a specific
928	signal one or more times. Even though signals are very asynchronous, libev	1171	signal one or more times. Even though signals are very asynchronous, libev
929	will try it's best to deliver signals synchronously, i.e. as part of the	1172	will try it's best to deliver signals synchronously, i.e. as part of the
930	normal event processing, like any other event.</p>	1173	normal event processing, like any other event.</p>
…		…
939	<dt>ev_signal_set (ev_signal *, int signum)</dt>	1182	<dt>ev_signal_set (ev_signal *, int signum)</dt>
940	<dd>	1183	<dd>
941	<p>Configures the watcher to trigger on the given signal number (usually one	1184	<p>Configures the watcher to trigger on the given signal number (usually one
942	of the <code>SIGxxx</code> constants).</p>	1185	of the <code>SIGxxx</code> constants).</p>
943	</dd>	1186	</dd>
		1187	<dt>int signum [read-only]</dt>
		1188	<dd>
		1189	<p>The signal the watcher watches out for.</p>
		1190	</dd>
944	</dl>	1191	</dl>
945		1192
946		1193
947		1194
948		1195
949		1196
950	</div>	1197	</div>
951	<h2 id="code_ev_child_code_wait_for_pid_stat"><code>ev_child</code> - wait for pid status changes</h2>	1198	<h2 id="code_ev_child_code_watch_out_for_pro"><code>ev_child</code> - watch out for process status changes</h2>
952	<div id="code_ev_child_code_wait_for_pid_stat-2">	1199	<div id="code_ev_child_code_watch_out_for_pro-2">
953	<p>Child watchers trigger when your process receives a SIGCHLD in response to	1200	<p>Child watchers trigger when your process receives a SIGCHLD in response to
954	some child status changes (most typically when a child of yours dies).</p>	1201	some child status changes (most typically when a child of yours dies).</p>
955	<dl>	1202	<dl>
956	<dt>ev_child_init (ev_child *, callback, int pid)</dt>	1203	<dt>ev_child_init (ev_child *, callback, int pid)</dt>
957	<dt>ev_child_set (ev_child *, int pid)</dt>	1204	<dt>ev_child_set (ev_child *, int pid)</dt>
…		…
961	at the <code>rstatus</code> member of the <code>ev_child</code> watcher structure to see	1208	at the <code>rstatus</code> member of the <code>ev_child</code> watcher structure to see
962	the status word (use the macros from <code>sys/wait.h</code> and see your systems	1209	the status word (use the macros from <code>sys/wait.h</code> and see your systems
963	<code>waitpid</code> documentation). The <code>rpid</code> member contains the pid of the	1210	<code>waitpid</code> documentation). The <code>rpid</code> member contains the pid of the
964	process causing the status change.</p>	1211	process causing the status change.</p>
965	</dd>	1212	</dd>
		1213	<dt>int pid [read-only]</dt>
		1214	<dd>
		1215	<p>The process id this watcher watches out for, or <code>0</code>, meaning any process id.</p>
		1216	</dd>
		1217	<dt>int rpid [read-write]</dt>
		1218	<dd>
		1219	<p>The process id that detected a status change.</p>
		1220	</dd>
		1221	<dt>int rstatus [read-write]</dt>
		1222	<dd>
		1223	<p>The process exit/trace status caused by <code>rpid</code> (see your systems
		1224	<code>waitpid</code> and <code>sys/wait.h</code> documentation for details).</p>
		1225	</dd>
966	</dl>	1226	</dl>
967	<p>Example: try to exit cleanly on SIGINT and SIGTERM.</p>	1227	<p>Example: Try to exit cleanly on SIGINT and SIGTERM.</p>
968	<pre> static void	1228	<pre> static void
969	sigint_cb (struct ev_loop loop, struct ev_signal w, int revents)	1229	sigint_cb (struct ev_loop loop, struct ev_signal w, int revents)
970	{	1230	{
971	ev_unloop (loop, EVUNLOOP_ALL);	1231	ev_unloop (loop, EVUNLOOP_ALL);
972	}	1232	}
…		…
979		1239
980		1240
981	</pre>	1241	</pre>
982		1242
983	</div>	1243	</div>
		1244	<h2 id="code_ev_stat_code_did_the_file_attri"><code>ev_stat</code> - did the file attributes just change?</h2>
		1245	<div id="code_ev_stat_code_did_the_file_attri-2">
		1246	<p>This watches a filesystem path for attribute changes. That is, it calls
		1247	<code>stat</code> regularly (or when the OS says it changed) and sees if it changed
		1248	compared to the last time, invoking the callback if it did.</p>
		1249	<p>The path does not need to exist: changing from "path exists" to "path does
		1250	not exist" is a status change like any other. The condition "path does
		1251	not exist" is signified by the <code>st_nlink</code> field being zero (which is
		1252	otherwise always forced to be at least one) and all the other fields of
		1253	the stat buffer having unspecified contents.</p>
		1254	<p>The path <i>should</i> be absolute and <i>must not</i> end in a slash. If it is
		1255	relative and your working directory changes, the behaviour is undefined.</p>
		1256	<p>Since there is no standard to do this, the portable implementation simply
		1257	calls <code>stat (2)</code> regularly on the path to see if it changed somehow. You
		1258	can specify a recommended polling interval for this case. If you specify
		1259	a polling interval of <code>0</code> (highly recommended!) then a <i>suitable,
		1260	unspecified default</i> value will be used (which you can expect to be around
		1261	five seconds, although this might change dynamically). Libev will also
		1262	impose a minimum interval which is currently around <code>0.1</code>, but thats
		1263	usually overkill.</p>
		1264	<p>This watcher type is not meant for massive numbers of stat watchers,
		1265	as even with OS-supported change notifications, this can be
		1266	resource-intensive.</p>
		1267	<p>At the time of this writing, only the Linux inotify interface is
		1268	implemented (implementing kqueue support is left as an exercise for the
		1269	reader). Inotify will be used to give hints only and should not change the
		1270	semantics of <code>ev_stat</code> watchers, which means that libev sometimes needs
		1271	to fall back to regular polling again even with inotify, but changes are
		1272	usually detected immediately, and if the file exists there will be no
		1273	polling.</p>
		1274	<dl>
		1275	<dt>ev_stat_init (ev_stat , callback, const char path, ev_tstamp interval)</dt>
		1276	<dt>ev_stat_set (ev_stat , const char path, ev_tstamp interval)</dt>
		1277	<dd>
		1278	<p>Configures the watcher to wait for status changes of the given
		1279	<code>path</code>. The <code>interval</code> is a hint on how quickly a change is expected to
		1280	be detected and should normally be specified as <code>0</code> to let libev choose
		1281	a suitable value. The memory pointed to by <code>path</code> must point to the same
		1282	path for as long as the watcher is active.</p>
		1283	<p>The callback will be receive <code>EV_STAT</code> when a change was detected,
		1284	relative to the attributes at the time the watcher was started (or the
		1285	last change was detected).</p>
		1286	</dd>
		1287	<dt>ev_stat_stat (ev_stat *)</dt>
		1288	<dd>
		1289	<p>Updates the stat buffer immediately with new values. If you change the
		1290	watched path in your callback, you could call this fucntion to avoid
		1291	detecting this change (while introducing a race condition). Can also be
		1292	useful simply to find out the new values.</p>
		1293	</dd>
		1294	<dt>ev_statdata attr [read-only]</dt>
		1295	<dd>
		1296	<p>The most-recently detected attributes of the file. Although the type is of
		1297	<code>ev_statdata</code>, this is usually the (or one of the) <code>struct stat</code> types
		1298	suitable for your system. If the <code>st_nlink</code> member is <code>0</code>, then there
		1299	was some error while <code>stat</code>ing the file.</p>
		1300	</dd>
		1301	<dt>ev_statdata prev [read-only]</dt>
		1302	<dd>
		1303	<p>The previous attributes of the file. The callback gets invoked whenever
		1304	<code>prev</code> != <code>attr</code>.</p>
		1305	</dd>
		1306	<dt>ev_tstamp interval [read-only]</dt>
		1307	<dd>
		1308	<p>The specified interval.</p>
		1309	</dd>
		1310	<dt>const char *path [read-only]</dt>
		1311	<dd>
		1312	<p>The filesystem path that is being watched.</p>
		1313	</dd>
		1314	</dl>
		1315	<p>Example: Watch <code>/etc/passwd</code> for attribute changes.</p>
		1316	<pre> static void
		1317	passwd_cb (struct ev_loop loop, ev_stat w, int revents)
		1318	{
		1319	/* /etc/passwd changed in some way */
		1320	if (w->attr.st_nlink)
		1321	{
		1322	printf ("passwd current size %ld\n", (long)w->attr.st_size);
		1323	printf ("passwd current atime %ld\n", (long)w->attr.st_mtime);
		1324	printf ("passwd current mtime %ld\n", (long)w->attr.st_mtime);
		1325	}
		1326	else
		1327	/* you shalt not abuse printf for puts */
		1328	puts ("wow, /etc/passwd is not there, expect problems. "
		1329	"if this is windows, they already arrived\n");
		1330	}
		1331
		1332	...
		1333	ev_stat passwd;
		1334
		1335	ev_stat_init (&passwd, passwd_cb, "/etc/passwd");
		1336	ev_stat_start (loop, &passwd);
		1337
		1338
		1339
		1340
		1341	</pre>
		1342
		1343	</div>
984	<h2 id="code_ev_idle_code_when_you_ve_got_no"><code>ev_idle</code> - when you've got nothing better to do</h2>	1344	<h2 id="code_ev_idle_code_when_you_ve_got_no"><code>ev_idle</code> - when you've got nothing better to do...</h2>
985	<div id="code_ev_idle_code_when_you_ve_got_no-2">	1345	<div id="code_ev_idle_code_when_you_ve_got_no-2">
986	<p>Idle watchers trigger events when there are no other events are pending	1346	<p>Idle watchers trigger events when there are no other events are pending
987	(prepare, check and other idle watchers do not count). That is, as long	1347	(prepare, check and other idle watchers do not count). That is, as long
988	as your process is busy handling sockets or timeouts (or even signals,	1348	as your process is busy handling sockets or timeouts (or even signals,
989	imagine) it will not be triggered. But when your process is idle all idle	1349	imagine) it will not be triggered. But when your process is idle all idle
…		…
1002	<p>Initialises and configures the idle watcher - it has no parameters of any	1362	<p>Initialises and configures the idle watcher - it has no parameters of any
1003	kind. There is a <code>ev_idle_set</code> macro, but using it is utterly pointless,	1363	kind. There is a <code>ev_idle_set</code> macro, but using it is utterly pointless,
1004	believe me.</p>	1364	believe me.</p>
1005	</dd>	1365	</dd>
1006	</dl>	1366	</dl>
1007	<p>Example: dynamically allocate an <code>ev_idle</code>, start it, and in the	1367	<p>Example: Dynamically allocate an <code>ev_idle</code> watcher, start it, and in the
1008	callback, free it. Alos, use no error checking, as usual.</p>	1368	callback, free it. Also, use no error checking, as usual.</p>
1009	<pre> static void	1369	<pre> static void
1010	idle_cb (struct ev_loop loop, struct ev_idle w, int revents)	1370	idle_cb (struct ev_loop loop, struct ev_idle w, int revents)
1011	{	1371	{
1012	free (w);	1372	free (w);
1013	// now do something you wanted to do when the program has	1373	// now do something you wanted to do when the program has
…		…
1022		1382
1023		1383
1024	</pre>	1384	</pre>
1025		1385
1026	</div>	1386	</div>
1027	<h2 id="code_ev_prepare_code_and_code_ev_che"><code>ev_prepare</code> and <code>ev_check</code> - customise your event loop</h2>	1387	<h2 id="code_ev_prepare_code_and_code_ev_che"><code>ev_prepare</code> and <code>ev_check</code> - customise your event loop!</h2>
1028	<div id="code_ev_prepare_code_and_code_ev_che-2">	1388	<div id="code_ev_prepare_code_and_code_ev_che-2">
1029	<p>Prepare and check watchers are usually (but not always) used in tandem:	1389	<p>Prepare and check watchers are usually (but not always) used in tandem:
1030	prepare watchers get invoked before the process blocks and check watchers	1390	prepare watchers get invoked before the process blocks and check watchers
1031	afterwards.</p>	1391	afterwards.</p>
		1392	<p>You <i>must not</i> call <code>ev_loop</code> or similar functions that enter
		1393	the current event loop from either <code>ev_prepare</code> or <code>ev_check</code>
		1394	watchers. Other loops than the current one are fine, however. The
		1395	rationale behind this is that you do not need to check for recursion in
		1396	those watchers, i.e. the sequence will always be <code>ev_prepare</code>, blocking,
		1397	<code>ev_check</code> so if you have one watcher of each kind they will always be
		1398	called in pairs bracketing the blocking call.</p>
1032	<p>Their main purpose is to integrate other event mechanisms into libev and	1399	<p>Their main purpose is to integrate other event mechanisms into libev and
1033	their use is somewhat advanced. This could be used, for example, to track	1400	their use is somewhat advanced. This could be used, for example, to track
1034	variable changes, implement your own watchers, integrate net-snmp or a	1401	variable changes, implement your own watchers, integrate net-snmp or a
1035	coroutine library and lots more.</p>	1402	coroutine library and lots more. They are also occasionally useful if
		1403	you cache some data and want to flush it before blocking (for example,
		1404	in X programs you might want to do an <code>XFlush ()</code> in an <code>ev_prepare</code>
		1405	watcher).</p>
1036	<p>This is done by examining in each prepare call which file descriptors need	1406	<p>This is done by examining in each prepare call which file descriptors need
1037	to be watched by the other library, registering <code>ev_io</code> watchers for	1407	to be watched by the other library, registering <code>ev_io</code> watchers for
1038	them and starting an <code>ev_timer</code> watcher for any timeouts (many libraries	1408	them and starting an <code>ev_timer</code> watcher for any timeouts (many libraries
1039	provide just this functionality). Then, in the check watcher you check for	1409	provide just this functionality). Then, in the check watcher you check for
1040	any events that occured (by checking the pending status of all watchers	1410	any events that occured (by checking the pending status of all watchers
…		…
1056	<p>Initialises and configures the prepare or check watcher - they have no	1426	<p>Initialises and configures the prepare or check watcher - they have no
1057	parameters of any kind. There are <code>ev_prepare_set</code> and <code>ev_check_set</code>	1427	parameters of any kind. There are <code>ev_prepare_set</code> and <code>ev_check_set</code>
1058	macros, but using them is utterly, utterly and completely pointless.</p>	1428	macros, but using them is utterly, utterly and completely pointless.</p>
1059	</dd>	1429	</dd>
1060	</dl>	1430	</dl>
1061	<p>Example: TODO.</p>	1431	<p>Example: To include a library such as adns, you would add IO watchers
		1432	and a timeout watcher in a prepare handler, as required by libadns, and
		1433	in a check watcher, destroy them and call into libadns. What follows is
		1434	pseudo-code only of course:</p>
		1435	<pre> static ev_io iow [nfd];
		1436	static ev_timer tw;
1062		1437
		1438	static void
		1439	io_cb (ev_loop loop, ev_io w, int revents)
		1440	{
		1441	// set the relevant poll flags
		1442	// could also call adns_processreadable etc. here
		1443	struct pollfd fd = (struct pollfd )w->data;
		1444	if (revents & EV_READ ) fd->revents \|= fd->events & POLLIN;
		1445	if (revents & EV_WRITE) fd->revents \|= fd->events & POLLOUT;
		1446	}
1063		1447
		1448	// create io watchers for each fd and a timer before blocking
		1449	static void
		1450	adns_prepare_cb (ev_loop loop, ev_prepare w, int revents)
		1451	{
		1452	int timeout = 3600000;truct pollfd fds [nfd];
		1453	// actual code will need to loop here and realloc etc.
		1454	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));
1064		1455
		1456	/* the callback is illegal, but won't be called as we stop during check */
		1457	ev_timer_init (&tw, 0, timeout * 1e-3);
		1458	ev_timer_start (loop, &tw);
1065		1459
		1460	// create on ev_io per pollfd
		1461	for (int i = 0; i < nfd; ++i)
		1462	{
		1463	ev_io_init (iow + i, io_cb, fds [i].fd,
		1464	((fds [i].events & POLLIN ? EV_READ : 0)
		1465	\| (fds [i].events & POLLOUT ? EV_WRITE : 0)));
1066		1466
		1467	fds [i].revents = 0;
		1468	iow [i].data = fds + i;
		1469	ev_io_start (loop, iow + i);
		1470	}
		1471	}
		1472
		1473	// stop all watchers after blocking
		1474	static void
		1475	adns_check_cb (ev_loop loop, ev_check w, int revents)
		1476	{
		1477	ev_timer_stop (loop, &tw);
		1478
		1479	for (int i = 0; i < nfd; ++i)
		1480	ev_io_stop (loop, iow + i);
		1481
		1482	adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));
		1483	}
		1484
		1485
		1486
		1487
		1488	</pre>
		1489
1067	</div>	1490	</div>
1068	<h2 id="code_ev_embed_code_when_one_backend_"><code>ev_embed</code> - when one backend isn't enough</h2>	1491	<h2 id="code_ev_embed_code_when_one_backend_"><code>ev_embed</code> - when one backend isn't enough...</h2>
1069	<div id="code_ev_embed_code_when_one_backend_-2">	1492	<div id="code_ev_embed_code_when_one_backend_-2">
1070	<p>This is a rather advanced watcher type that lets you embed one event loop	1493	<p>This is a rather advanced watcher type that lets you embed one event loop
1071	into another.</p>	1494	into another (currently only <code>ev_io</code> events are supported in the embedded
		1495	loop, other types of watchers might be handled in a delayed or incorrect
		1496	fashion and must not be used).</p>
1072	<p>There are primarily two reasons you would want that: work around bugs and	1497	<p>There are primarily two reasons you would want that: work around bugs and
1073	prioritise I/O.</p>	1498	prioritise I/O.</p>
1074	<p>As an example for a bug workaround, the kqueue backend might only support	1499	<p>As an example for a bug workaround, the kqueue backend might only support
1075	sockets on some platform, so it is unusable as generic backend, but you	1500	sockets on some platform, so it is unusable as generic backend, but you
1076	still want to make use of it because you have many sockets and it scales	1501	still want to make use of it because you have many sockets and it scales
…		…
1081	<p>As for prioritising I/O: rarely you have the case where some fds have	1506	<p>As for prioritising I/O: rarely you have the case where some fds have
1082	to be watched and handled very quickly (with low latency), and even	1507	to be watched and handled very quickly (with low latency), and even
1083	priorities and idle watchers might have too much overhead. In this case	1508	priorities and idle watchers might have too much overhead. In this case
1084	you would put all the high priority stuff in one loop and all the rest in	1509	you would put all the high priority stuff in one loop and all the rest in
1085	a second one, and embed the second one in the first.</p>	1510	a second one, and embed the second one in the first.</p>
		1511	<p>As long as the watcher is active, the callback will be invoked every time
		1512	there might be events pending in the embedded loop. The callback must then
		1513	call <code>ev_embed_sweep (mainloop, watcher)</code> to make a single sweep and invoke
		1514	their callbacks (you could also start an idle watcher to give the embedded
		1515	loop strictly lower priority for example). You can also set the callback
		1516	to <code>0</code>, in which case the embed watcher will automatically execute the
		1517	embedded loop sweep.</p>
1086	<p>As long as the watcher is started it will automatically handle events. The	1518	<p>As long as the watcher is started it will automatically handle events. The
1087	callback will be invoked whenever some events have been handled. You can	1519	callback will be invoked whenever some events have been handled. You can
1088	set the callback to <code>0</code> to avoid having to specify one if you are not	1520	set the callback to <code>0</code> to avoid having to specify one if you are not
1089	interested in that.</p>	1521	interested in that.</p>
1090	<p>Also, there have not currently been made special provisions for forking:	1522	<p>Also, there have not currently been made special provisions for forking:
…		…
1117	else	1549	else
1118	loop_lo = loop_hi;	1550	loop_lo = loop_hi;
1119		1551
1120	</pre>	1552	</pre>
1121	<dl>	1553	<dl>
1122	<dt>ev_embed_init (ev_embed , callback, struct ev_loop loop)</dt>	1554	<dt>ev_embed_init (ev_embed , callback, struct ev_loop embedded_loop)</dt>
1123	<dt>ev_embed_set (ev_embed , callback, struct ev_loop loop)</dt>	1555	<dt>ev_embed_set (ev_embed , callback, struct ev_loop embedded_loop)</dt>
		1556	<dd>
		1557	<p>Configures the watcher to embed the given loop, which must be
		1558	embeddable. If the callback is <code>0</code>, then <code>ev_embed_sweep</code> will be
		1559	invoked automatically, otherwise it is the responsibility of the callback
		1560	to invoke it (it will continue to be called until the sweep has been done,
		1561	if you do not want thta, you need to temporarily stop the embed watcher).</p>
1124	<dd>	1562	</dd>
1125	<p>Configures the watcher to embed the given loop, which must be embeddable.</p>	1563	<dt>ev_embed_sweep (loop, ev_embed *)</dt>
		1564	<dd>
		1565	<p>Make a single, non-blocking sweep over the embedded loop. This works
		1566	similarly to <code>ev_loop (embedded_loop, EVLOOP_NONBLOCK)</code>, but in the most
		1567	apropriate way for embedded loops.</p>
		1568	</dd>
		1569	<dt>struct ev_loop *loop [read-only]</dt>
		1570	<dd>
		1571	<p>The embedded event loop.</p>
1126	</dd>	1572	</dd>
1127	</dl>	1573	</dl>
1128		1574
1129		1575
1130		1576
1131		1577
1132		1578
1133	</div>	1579	</div>
1134	<h1 id="OTHER_FUNCTIONS">OTHER FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p>	1580	<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>
		1581	<div id="code_ev_fork_code_the_audacity_to_re-2">
		1582	<p>Fork watchers are called when a <code>fork ()</code> was detected (usually because
		1583	whoever is a good citizen cared to tell libev about it by calling
		1584	<code>ev_default_fork</code> or <code>ev_loop_fork</code>). The invocation is done before the
		1585	event loop blocks next and before <code>ev_check</code> watchers are being called,
		1586	and only in the child after the fork. If whoever good citizen calling
		1587	<code>ev_default_fork</code> cheats and calls it in the wrong process, the fork
		1588	handlers will be invoked, too, of course.</p>
		1589	<dl>
		1590	<dt>ev_fork_init (ev_signal *, callback)</dt>
		1591	<dd>
		1592	<p>Initialises and configures the fork watcher - it has no parameters of any
		1593	kind. There is a <code>ev_fork_set</code> macro, but using it is utterly pointless,
		1594	believe me.</p>
		1595	</dd>
		1596	</dl>
		1597
		1598
		1599
		1600
		1601
		1602	</div>
		1603	<h1 id="OTHER_FUNCTIONS">OTHER FUNCTIONS</h1>
1135	<div id="OTHER_FUNCTIONS_CONTENT">	1604	<div id="OTHER_FUNCTIONS_CONTENT">
1136	<p>There are some other functions of possible interest. Described. Here. Now.</p>	1605	<p>There are some other functions of possible interest. Described. Here. Now.</p>
1137	<dl>	1606	<dl>
1138	<dt>ev_once (loop, int fd, int events, ev_tstamp timeout, callback)</dt>	1607	<dt>ev_once (loop, int fd, int events, ev_tstamp timeout, callback)</dt>
1139	<dd>	1608	<dd>
…		…
1163		1632
1164	ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);	1633	ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);
1165		1634
1166	</pre>	1635	</pre>
1167	</dd>	1636	</dd>
1168	<dt>ev_feed_event (loop, watcher, int events)</dt>	1637	<dt>ev_feed_event (ev_loop , watcher , int revents)</dt>
1169	<dd>	1638	<dd>
1170	<p>Feeds the given event set into the event loop, as if the specified event	1639	<p>Feeds the given event set into the event loop, as if the specified event
1171	had happened for the specified watcher (which must be a pointer to an	1640	had happened for the specified watcher (which must be a pointer to an
1172	initialised but not necessarily started event watcher).</p>	1641	initialised but not necessarily started event watcher).</p>
1173	</dd>	1642	</dd>
1174	<dt>ev_feed_fd_event (loop, int fd, int revents)</dt>	1643	<dt>ev_feed_fd_event (ev_loop *, int fd, int revents)</dt>
1175	<dd>	1644	<dd>
1176	<p>Feed an event on the given fd, as if a file descriptor backend detected	1645	<p>Feed an event on the given fd, as if a file descriptor backend detected
1177	the given events it.</p>	1646	the given events it.</p>
1178	</dd>	1647	</dd>
1179	<dt>ev_feed_signal_event (loop, int signum)</dt>	1648	<dt>ev_feed_signal_event (ev_loop *loop, int signum)</dt>
1180	<dd>	1649	<dd>
1181	<p>Feed an event as if the given signal occured (loop must be the default loop!).</p>	1650	<p>Feed an event as if the given signal occured (<code>loop</code> must be the default
		1651	loop!).</p>
1182	</dd>	1652	</dd>
1183	</dl>	1653	</dl>
1184		1654
1185		1655
1186		1656
1187		1657
1188		1658
1189	</div>	1659	</div>
1190	<h1 id="LIBEVENT_EMULATION">LIBEVENT EMULATION</h1><p><a href="#TOP" class="toplink">Top</a></p>	1660	<h1 id="LIBEVENT_EMULATION">LIBEVENT EMULATION</h1>
1191	<div id="LIBEVENT_EMULATION_CONTENT">	1661	<div id="LIBEVENT_EMULATION_CONTENT">
1192	<p>Libev offers a compatibility emulation layer for libevent. It cannot	1662	<p>Libev offers a compatibility emulation layer for libevent. It cannot
1193	emulate the internals of libevent, so here are some usage hints:</p>	1663	emulate the internals of libevent, so here are some usage hints:</p>
1194	<dl>	1664	<dl>
1195	<dt>* Use it by including <event.h>, as usual.</dt>	1665	<dt>* Use it by including <event.h>, as usual.</dt>
…		…
1205	<dt>* The libev emulation is <i>not</i> ABI compatible to libevent, you need	1675	<dt>* The libev emulation is <i>not</i> ABI compatible to libevent, you need
1206	to use the libev header file and library.</dt>	1676	to use the libev header file and library.</dt>
1207	</dl>	1677	</dl>
1208		1678
1209	</div>	1679	</div>
1210	<h1 id="C_SUPPORT">C++ SUPPORT</h1><p><a href="#TOP" class="toplink">Top</a></p>	1680	<h1 id="C_SUPPORT">C++ SUPPORT</h1>
1211	<div id="C_SUPPORT_CONTENT">	1681	<div id="C_SUPPORT_CONTENT">
1212	<p>TBD.</p>	1682	<p>Libev comes with some simplistic wrapper classes for C++ that mainly allow
		1683	you to use some convinience methods to start/stop watchers and also change
		1684	the callback model to a model using method callbacks on objects.</p>
		1685	<p>To use it,</p>
		1686	<pre> #include <ev++.h>
1213		1687
		1688	</pre>
		1689	<p>(it is not installed by default). This automatically includes <cite>ev.h</cite>
		1690	and puts all of its definitions (many of them macros) into the global
		1691	namespace. All C++ specific things are put into the <code>ev</code> namespace.</p>
		1692	<p>It should support all the same embedding options as <cite>ev.h</cite>, most notably
		1693	<code>EV_MULTIPLICITY</code>.</p>
		1694	<p>Here is a list of things available in the <code>ev</code> namespace:</p>
		1695	<dl>
		1696	<dt><code>ev::READ</code>, <code>ev::WRITE</code> etc.</dt>
		1697	<dd>
		1698	<p>These are just enum values with the same values as the <code>EV_READ</code> etc.
		1699	macros from <cite>ev.h</cite>.</p>
		1700	</dd>
		1701	<dt><code>ev::tstamp</code>, <code>ev::now</code></dt>
		1702	<dd>
		1703	<p>Aliases to the same types/functions as with the <code>ev_</code> prefix.</p>
		1704	</dd>
		1705	<dt><code>ev::io</code>, <code>ev::timer</code>, <code>ev::periodic</code>, <code>ev::idle</code>, <code>ev::sig</code> etc.</dt>
		1706	<dd>
		1707	<p>For each <code>ev_TYPE</code> watcher in <cite>ev.h</cite> there is a corresponding class of
		1708	the same name in the <code>ev</code> namespace, with the exception of <code>ev_signal</code>
		1709	which is called <code>ev::sig</code> to avoid clashes with the <code>signal</code> macro
		1710	defines by many implementations.</p>
		1711	<p>All of those classes have these methods:</p>
		1712	<p>
		1713	<dl>
		1714	<dt>ev::TYPE::TYPE (object , object::method )</dt>
		1715	<dt>ev::TYPE::TYPE (object , object::method , struct ev_loop *)</dt>
		1716	<dt>ev::TYPE::~TYPE</dt>
		1717	<dd>
		1718	<p>The constructor takes a pointer to an object and a method pointer to
		1719	the event handler callback to call in this class. The constructor calls
		1720	<code>ev_init</code> for you, which means you have to call the <code>set</code> method
		1721	before starting it. If you do not specify a loop then the constructor
		1722	automatically associates the default loop with this watcher.</p>
		1723	<p>The destructor automatically stops the watcher if it is active.</p>
		1724	</dd>
		1725	<dt>w->set (struct ev_loop *)</dt>
		1726	<dd>
		1727	<p>Associates a different <code>struct ev_loop</code> with this watcher. You can only
		1728	do this when the watcher is inactive (and not pending either).</p>
		1729	</dd>
		1730	<dt>w->set ([args])</dt>
		1731	<dd>
		1732	<p>Basically the same as <code>ev_TYPE_set</code>, with the same args. Must be
		1733	called at least once. Unlike the C counterpart, an active watcher gets
		1734	automatically stopped and restarted.</p>
		1735	</dd>
		1736	<dt>w->start ()</dt>
		1737	<dd>
		1738	<p>Starts the watcher. Note that there is no <code>loop</code> argument as the
		1739	constructor already takes the loop.</p>
		1740	</dd>
		1741	<dt>w->stop ()</dt>
		1742	<dd>
		1743	<p>Stops the watcher if it is active. Again, no <code>loop</code> argument.</p>
		1744	</dd>
		1745	<dt>w->again () <code>ev::timer</code>, <code>ev::periodic</code> only</dt>
		1746	<dd>
		1747	<p>For <code>ev::timer</code> and <code>ev::periodic</code>, this invokes the corresponding
		1748	<code>ev_TYPE_again</code> function.</p>
		1749	</dd>
		1750	<dt>w->sweep () <code>ev::embed</code> only</dt>
		1751	<dd>
		1752	<p>Invokes <code>ev_embed_sweep</code>.</p>
		1753	</dd>
		1754	<dt>w->update () <code>ev::stat</code> only</dt>
		1755	<dd>
		1756	<p>Invokes <code>ev_stat_stat</code>.</p>
		1757	</dd>
		1758	</dl>
		1759	</p>
		1760	</dd>
		1761	</dl>
		1762	<p>Example: Define a class with an IO and idle watcher, start one of them in
		1763	the constructor.</p>
		1764	<pre> class myclass
		1765	{
		1766	ev_io io; void io_cb (ev::io &w, int revents);
		1767	ev_idle idle void idle_cb (ev::idle &w, int revents);
		1768
		1769	myclass ();
		1770	}
		1771
		1772	myclass::myclass (int fd)
		1773	: io (this, &myclass::io_cb),
		1774	idle (this, &myclass::idle_cb)
		1775	{
		1776	io.start (fd, ev::READ);
		1777	}
		1778
		1779
		1780
		1781
		1782	</pre>
		1783
1214	</div>	1784	</div>
1215	<h1 id="AUTHOR">AUTHOR</h1><p><a href="#TOP" class="toplink">Top</a></p>	1785	<h1 id="MACRO_MAGIC">MACRO MAGIC</h1>
		1786	<div id="MACRO_MAGIC_CONTENT">
		1787	<p>Libev can be compiled with a variety of options, the most fundemantal is
		1788	<code>EV_MULTIPLICITY</code>. This option determines wether (most) functions and
		1789	callbacks have an initial <code>struct ev_loop *</code> argument.</p>
		1790	<p>To make it easier to write programs that cope with either variant, the
		1791	following macros are defined:</p>
		1792	<dl>
		1793	<dt><code>EV_A</code>, <code>EV_A_</code></dt>
		1794	<dd>
		1795	<p>This provides the loop <i>argument</i> for functions, if one is required ("ev
		1796	loop argument"). The <code>EV_A</code> form is used when this is the sole argument,
		1797	<code>EV_A_</code> is used when other arguments are following. Example:</p>
		1798	<pre> ev_unref (EV_A);
		1799	ev_timer_add (EV_A_ watcher);
		1800	ev_loop (EV_A_ 0);
		1801
		1802	</pre>
		1803	<p>It assumes the variable <code>loop</code> of type <code>struct ev_loop *</code> is in scope,
		1804	which is often provided by the following macro.</p>
		1805	</dd>
		1806	<dt><code>EV_P</code>, <code>EV_P_</code></dt>
		1807	<dd>
		1808	<p>This provides the loop <i>parameter</i> for functions, if one is required ("ev
		1809	loop parameter"). The <code>EV_P</code> form is used when this is the sole parameter,
		1810	<code>EV_P_</code> is used when other parameters are following. Example:</p>
		1811	<pre> // this is how ev_unref is being declared
		1812	static void ev_unref (EV_P);
		1813
		1814	// this is how you can declare your typical callback
		1815	static void cb (EV_P_ ev_timer *w, int revents)
		1816
		1817	</pre>
		1818	<p>It declares a parameter <code>loop</code> of type <code>struct ev_loop *</code>, quite
		1819	suitable for use with <code>EV_A</code>.</p>
		1820	</dd>
		1821	<dt><code>EV_DEFAULT</code>, <code>EV_DEFAULT_</code></dt>
		1822	<dd>
		1823	<p>Similar to the other two macros, this gives you the value of the default
		1824	loop, if multiple loops are supported ("ev loop default").</p>
		1825	</dd>
		1826	</dl>
		1827	<p>Example: Declare and initialise a check watcher, working regardless of
		1828	wether multiple loops are supported or not.</p>
		1829	<pre> static void
		1830	check_cb (EV_P_ ev_timer *w, int revents)
		1831	{
		1832	ev_check_stop (EV_A_ w);
		1833	}
		1834
		1835	ev_check check;
		1836	ev_check_init (&check, check_cb);
		1837	ev_check_start (EV_DEFAULT_ &check);
		1838	ev_loop (EV_DEFAULT_ 0);
		1839
		1840
		1841
		1842
		1843	</pre>
		1844
		1845	</div>
		1846	<h1 id="EMBEDDING">EMBEDDING</h1>
		1847	<div id="EMBEDDING_CONTENT">
		1848	<p>Libev can (and often is) directly embedded into host
		1849	applications. Examples of applications that embed it include the Deliantra
		1850	Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe)
		1851	and rxvt-unicode.</p>
		1852	<p>The goal is to enable you to just copy the neecssary files into your
		1853	source directory without having to change even a single line in them, so
		1854	you can easily upgrade by simply copying (or having a checked-out copy of
		1855	libev somewhere in your source tree).</p>
		1856
		1857	</div>
		1858	<h2 id="FILESETS">FILESETS</h2>
		1859	<div id="FILESETS_CONTENT">
		1860	<p>Depending on what features you need you need to include one or more sets of files
		1861	in your app.</p>
		1862
		1863	</div>
		1864	<h3 id="CORE_EVENT_LOOP">CORE EVENT LOOP</h3>
		1865	<div id="CORE_EVENT_LOOP_CONTENT">
		1866	<p>To include only the libev core (all the <code>ev_*</code> functions), with manual
		1867	configuration (no autoconf):</p>
		1868	<pre> #define EV_STANDALONE 1
		1869	#include "ev.c"
		1870
		1871	</pre>
		1872	<p>This will automatically include <cite>ev.h</cite>, too, and should be done in a
		1873	single C source file only to provide the function implementations. To use
		1874	it, do the same for <cite>ev.h</cite> in all files wishing to use this API (best
		1875	done by writing a wrapper around <cite>ev.h</cite> that you can include instead and
		1876	where you can put other configuration options):</p>
		1877	<pre> #define EV_STANDALONE 1
		1878	#include "ev.h"
		1879
		1880	</pre>
		1881	<p>Both header files and implementation files can be compiled with a C++
		1882	compiler (at least, thats a stated goal, and breakage will be treated
		1883	as a bug).</p>
		1884	<p>You need the following files in your source tree, or in a directory
		1885	in your include path (e.g. in libev/ when using -Ilibev):</p>
		1886	<pre> ev.h
		1887	ev.c
		1888	ev_vars.h
		1889	ev_wrap.h
		1890
		1891	ev_win32.c required on win32 platforms only
		1892
		1893	ev_select.c only when select backend is enabled (which is by default)
		1894	ev_poll.c only when poll backend is enabled (disabled by default)
		1895	ev_epoll.c only when the epoll backend is enabled (disabled by default)
		1896	ev_kqueue.c only when the kqueue backend is enabled (disabled by default)
		1897	ev_port.c only when the solaris port backend is enabled (disabled by default)
		1898
		1899	</pre>
		1900	<p><cite>ev.c</cite> includes the backend files directly when enabled, so you only need
		1901	to compile this single file.</p>
		1902
		1903	</div>
		1904	<h3 id="LIBEVENT_COMPATIBILITY_API">LIBEVENT COMPATIBILITY API</h3>
		1905	<div id="LIBEVENT_COMPATIBILITY_API_CONTENT">
		1906	<p>To include the libevent compatibility API, also include:</p>
		1907	<pre> #include "event.c"
		1908
		1909	</pre>
		1910	<p>in the file including <cite>ev.c</cite>, and:</p>
		1911	<pre> #include "event.h"
		1912
		1913	</pre>
		1914	<p>in the files that want to use the libevent API. This also includes <cite>ev.h</cite>.</p>
		1915	<p>You need the following additional files for this:</p>
		1916	<pre> event.h
		1917	event.c
		1918
		1919	</pre>
		1920
		1921	</div>
		1922	<h3 id="AUTOCONF_SUPPORT">AUTOCONF SUPPORT</h3>
		1923	<div id="AUTOCONF_SUPPORT_CONTENT">
		1924	<p>Instead of using <code>EV_STANDALONE=1</code> and providing your config in
		1925	whatever way you want, you can also <code>m4_include([libev.m4])</code> in your
		1926	<cite>configure.ac</cite> and leave <code>EV_STANDALONE</code> undefined. <cite>ev.c</cite> will then
		1927	include <cite>config.h</cite> and configure itself accordingly.</p>
		1928	<p>For this of course you need the m4 file:</p>
		1929	<pre> libev.m4
		1930
		1931	</pre>
		1932
		1933	</div>
		1934	<h2 id="PREPROCESSOR_SYMBOLS_MACROS">PREPROCESSOR SYMBOLS/MACROS</h2>
		1935	<div id="PREPROCESSOR_SYMBOLS_MACROS_CONTENT">
		1936	<p>Libev can be configured via a variety of preprocessor symbols you have to define
		1937	before including any of its files. The default is not to build for multiplicity
		1938	and only include the select backend.</p>
		1939	<dl>
		1940	<dt>EV_STANDALONE</dt>
		1941	<dd>
		1942	<p>Must always be <code>1</code> if you do not use autoconf configuration, which
		1943	keeps libev from including <cite>config.h</cite>, and it also defines dummy
		1944	implementations for some libevent functions (such as logging, which is not
		1945	supported). It will also not define any of the structs usually found in
		1946	<cite>event.h</cite> that are not directly supported by the libev core alone.</p>
		1947	</dd>
		1948	<dt>EV_USE_MONOTONIC</dt>
		1949	<dd>
		1950	<p>If defined to be <code>1</code>, libev will try to detect the availability of the
		1951	monotonic clock option at both compiletime and runtime. Otherwise no use
		1952	of the monotonic clock option will be attempted. If you enable this, you
		1953	usually have to link against librt or something similar. Enabling it when
		1954	the functionality isn't available is safe, though, althoguh you have
		1955	to make sure you link against any libraries where the <code>clock_gettime</code>
		1956	function is hiding in (often <cite>-lrt</cite>).</p>
		1957	</dd>
		1958	<dt>EV_USE_REALTIME</dt>
		1959	<dd>
		1960	<p>If defined to be <code>1</code>, libev will try to detect the availability of the
		1961	realtime clock option at compiletime (and assume its availability at
		1962	runtime if successful). Otherwise no use of the realtime clock option will
		1963	be attempted. This effectively replaces <code>gettimeofday</code> by <code>clock_get
		1964	(CLOCK_REALTIME, ...)</code> and will not normally affect correctness. See tzhe note about libraries
		1965	in the description of <code>EV_USE_MONOTONIC</code>, though.</p>
		1966	</dd>
		1967	<dt>EV_USE_SELECT</dt>
		1968	<dd>
		1969	<p>If undefined or defined to be <code>1</code>, libev will compile in support for the
		1970	<code>select</code>(2) backend. No attempt at autodetection will be done: if no
		1971	other method takes over, select will be it. Otherwise the select backend
		1972	will not be compiled in.</p>
		1973	</dd>
		1974	<dt>EV_SELECT_USE_FD_SET</dt>
		1975	<dd>
		1976	<p>If defined to <code>1</code>, then the select backend will use the system <code>fd_set</code>
		1977	structure. This is useful if libev doesn't compile due to a missing
		1978	<code>NFDBITS</code> or <code>fd_mask</code> definition or it misguesses the bitset layout on
		1979	exotic systems. This usually limits the range of file descriptors to some
		1980	low limit such as 1024 or might have other limitations (winsocket only
		1981	allows 64 sockets). The <code>FD_SETSIZE</code> macro, set before compilation, might
		1982	influence the size of the <code>fd_set</code> used.</p>
		1983	</dd>
		1984	<dt>EV_SELECT_IS_WINSOCKET</dt>
		1985	<dd>
		1986	<p>When defined to <code>1</code>, the select backend will assume that
		1987	select/socket/connect etc. don't understand file descriptors but
		1988	wants osf handles on win32 (this is the case when the select to
		1989	be used is the winsock select). This means that it will call
		1990	<code>_get_osfhandle</code> on the fd to convert it to an OS handle. Otherwise,
		1991	it is assumed that all these functions actually work on fds, even
		1992	on win32. Should not be defined on non-win32 platforms.</p>
		1993	</dd>
		1994	<dt>EV_USE_POLL</dt>
		1995	<dd>
		1996	<p>If defined to be <code>1</code>, libev will compile in support for the <code>poll</code>(2)
		1997	backend. Otherwise it will be enabled on non-win32 platforms. It
		1998	takes precedence over select.</p>
		1999	</dd>
		2000	<dt>EV_USE_EPOLL</dt>
		2001	<dd>
		2002	<p>If defined to be <code>1</code>, libev will compile in support for the Linux
		2003	<code>epoll</code>(7) backend. Its availability will be detected at runtime,
		2004	otherwise another method will be used as fallback. This is the
		2005	preferred backend for GNU/Linux systems.</p>
		2006	</dd>
		2007	<dt>EV_USE_KQUEUE</dt>
		2008	<dd>
		2009	<p>If defined to be <code>1</code>, libev will compile in support for the BSD style
		2010	<code>kqueue</code>(2) backend. Its actual availability will be detected at runtime,
		2011	otherwise another method will be used as fallback. This is the preferred
		2012	backend for BSD and BSD-like systems, although on most BSDs kqueue only
		2013	supports some types of fds correctly (the only platform we found that
		2014	supports ptys for example was NetBSD), so kqueue might be compiled in, but
		2015	not be used unless explicitly requested. The best way to use it is to find
		2016	out whether kqueue supports your type of fd properly and use an embedded
		2017	kqueue loop.</p>
		2018	</dd>
		2019	<dt>EV_USE_PORT</dt>
		2020	<dd>
		2021	<p>If defined to be <code>1</code>, libev will compile in support for the Solaris
		2022	10 port style backend. Its availability will be detected at runtime,
		2023	otherwise another method will be used as fallback. This is the preferred
		2024	backend for Solaris 10 systems.</p>
		2025	</dd>
		2026	<dt>EV_USE_DEVPOLL</dt>
		2027	<dd>
		2028	<p>reserved for future expansion, works like the USE symbols above.</p>
		2029	</dd>
		2030	<dt>EV_USE_INOTIFY</dt>
		2031	<dd>
		2032	<p>If defined to be <code>1</code>, libev will compile in support for the Linux inotify
		2033	interface to speed up <code>ev_stat</code> watchers. Its actual availability will
		2034	be detected at runtime.</p>
		2035	</dd>
		2036	<dt>EV_H</dt>
		2037	<dd>
		2038	<p>The name of the <cite>ev.h</cite> header file used to include it. The default if
		2039	undefined is <code><ev.h></code> in <cite>event.h</cite> and <code>"ev.h"</code> in <cite>ev.c</cite>. This
		2040	can be used to virtually rename the <cite>ev.h</cite> header file in case of conflicts.</p>
		2041	</dd>
		2042	<dt>EV_CONFIG_H</dt>
		2043	<dd>
		2044	<p>If <code>EV_STANDALONE</code> isn't <code>1</code>, this variable can be used to override
		2045	<cite>ev.c</cite>'s idea of where to find the <cite>config.h</cite> file, similarly to
		2046	<code>EV_H</code>, above.</p>
		2047	</dd>
		2048	<dt>EV_EVENT_H</dt>
		2049	<dd>
		2050	<p>Similarly to <code>EV_H</code>, this macro can be used to override <cite>event.c</cite>'s idea
		2051	of how the <cite>event.h</cite> header can be found.</p>
		2052	</dd>
		2053	<dt>EV_PROTOTYPES</dt>
		2054	<dd>
		2055	<p>If defined to be <code>0</code>, then <cite>ev.h</cite> will not define any function
		2056	prototypes, but still define all the structs and other symbols. This is
		2057	occasionally useful if you want to provide your own wrapper functions
		2058	around libev functions.</p>
		2059	</dd>
		2060	<dt>EV_MULTIPLICITY</dt>
		2061	<dd>
		2062	<p>If undefined or defined to <code>1</code>, then all event-loop-specific functions
		2063	will have the <code>struct ev_loop *</code> as first argument, and you can create
		2064	additional independent event loops. Otherwise there will be no support
		2065	for multiple event loops and there is no first event loop pointer
		2066	argument. Instead, all functions act on the single default loop.</p>
		2067	</dd>
		2068	<dt>EV_PERIODIC_ENABLE</dt>
		2069	<dd>
		2070	<p>If undefined or defined to be <code>1</code>, then periodic timers are supported. If
		2071	defined to be <code>0</code>, then they are not. Disabling them saves a few kB of
		2072	code.</p>
		2073	</dd>
		2074	<dt>EV_EMBED_ENABLE</dt>
		2075	<dd>
		2076	<p>If undefined or defined to be <code>1</code>, then embed watchers are supported. If
		2077	defined to be <code>0</code>, then they are not.</p>
		2078	</dd>
		2079	<dt>EV_STAT_ENABLE</dt>
		2080	<dd>
		2081	<p>If undefined or defined to be <code>1</code>, then stat watchers are supported. If
		2082	defined to be <code>0</code>, then they are not.</p>
		2083	</dd>
		2084	<dt>EV_FORK_ENABLE</dt>
		2085	<dd>
		2086	<p>If undefined or defined to be <code>1</code>, then fork watchers are supported. If
		2087	defined to be <code>0</code>, then they are not.</p>
		2088	</dd>
		2089	<dt>EV_MINIMAL</dt>
		2090	<dd>
		2091	<p>If you need to shave off some kilobytes of code at the expense of some
		2092	speed, define this symbol to <code>1</code>. Currently only used for gcc to override
		2093	some inlining decisions, saves roughly 30% codesize of amd64.</p>
		2094	</dd>
		2095	<dt>EV_PID_HASHSIZE</dt>
		2096	<dd>
		2097	<p><code>ev_child</code> watchers use a small hash table to distribute workload by
		2098	pid. The default size is <code>16</code> (or <code>1</code> with <code>EV_MINIMAL</code>), usually more
		2099	than enough. If you need to manage thousands of children you might want to
		2100	increase this value (<i>must</i> be a power of two).</p>
		2101	</dd>
		2102	<dt>EV_INOTIFY_HASHSIZE</dt>
		2103	<dd>
		2104	<p><code>ev_staz</code> watchers use a small hash table to distribute workload by
		2105	inotify watch id. The default size is <code>16</code> (or <code>1</code> with <code>EV_MINIMAL</code>),
		2106	usually more than enough. If you need to manage thousands of <code>ev_stat</code>
		2107	watchers you might want to increase this value (<i>must</i> be a power of
		2108	two).</p>
		2109	</dd>
		2110	<dt>EV_COMMON</dt>
		2111	<dd>
		2112	<p>By default, all watchers have a <code>void *data</code> member. By redefining
		2113	this macro to a something else you can include more and other types of
		2114	members. You have to define it each time you include one of the files,
		2115	though, and it must be identical each time.</p>
		2116	<p>For example, the perl EV module uses something like this:</p>
		2117	<pre> #define EV_COMMON \
		2118	SV self; / contains this struct */ \
		2119	SV cb_sv, fh /* note no trailing ";" */
		2120
		2121	</pre>
		2122	</dd>
		2123	<dt>EV_CB_DECLARE (type)</dt>
		2124	<dt>EV_CB_INVOKE (watcher, revents)</dt>
		2125	<dt>ev_set_cb (ev, cb)</dt>
		2126	<dd>
		2127	<p>Can be used to change the callback member declaration in each watcher,
		2128	and the way callbacks are invoked and set. Must expand to a struct member
		2129	definition and a statement, respectively. See the <cite>ev.v</cite> header file for
		2130	their default definitions. One possible use for overriding these is to
		2131	avoid the <code>struct ev_loop *</code> as first argument in all cases, or to use
		2132	method calls instead of plain function calls in C++.</p>
		2133
		2134	</div>
		2135	<h2 id="EXAMPLES">EXAMPLES</h2>
		2136	<div id="EXAMPLES_CONTENT">
		2137	<p>For a real-world example of a program the includes libev
		2138	verbatim, you can have a look at the EV perl module
		2139	(<a href="http://software.schmorp.de/pkg/EV.html">http://software.schmorp.de/pkg/EV.html</a>). It has the libev files in
		2140	the <cite>libev/</cite> subdirectory and includes them in the <cite>EV/EVAPI.h</cite> (public
		2141	interface) and <cite>EV.xs</cite> (implementation) files. Only the <cite>EV.xs</cite> file
		2142	will be compiled. It is pretty complex because it provides its own header
		2143	file.</p>
		2144	<p>The usage in rxvt-unicode is simpler. It has a <cite>ev_cpp.h</cite> header file
		2145	that everybody includes and which overrides some autoconf choices:</p>
		2146	<pre> #define EV_USE_POLL 0
		2147	#define EV_MULTIPLICITY 0
		2148	#define EV_PERIODICS 0
		2149	#define EV_CONFIG_H <config.h>
		2150
		2151	#include "ev++.h"
		2152
		2153	</pre>
		2154	<p>And a <cite>ev_cpp.C</cite> implementation file that contains libev proper and is compiled:</p>
		2155	<pre> #include "ev_cpp.h"
		2156	#include "ev.c"
		2157
		2158
		2159
		2160
		2161	</pre>
		2162
		2163	</div>
		2164	<h1 id="COMPLEXITIES">COMPLEXITIES</h1>
		2165	<div id="COMPLEXITIES_CONTENT">
		2166	<p>In this section the complexities of (many of) the algorithms used inside
		2167	libev will be explained. For complexity discussions about backends see the
		2168	documentation for <code>ev_default_init</code>.</p>
		2169	<p>
		2170	<dl>
		2171	<dt>Starting and stopping timer/periodic watchers: O(log skipped_other_timers)</dt>
		2172	<dt>Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)</dt>
		2173	<dt>Starting io/check/prepare/idle/signal/child watchers: O(1)</dt>
		2174	<dt>Stopping check/prepare/idle watchers: O(1)</dt>
		2175	<dt>Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))</dt>
		2176	<dt>Finding the next timer per loop iteration: O(1)</dt>
		2177	<dt>Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)</dt>
		2178	<dt>Activating one watcher: O(1)</dt>
		2179	</dl>
		2180	</p>
		2181
		2182
		2183
		2184
		2185
		2186	</div>
		2187	<h1 id="AUTHOR">AUTHOR</h1>
1216	<div id="AUTHOR_CONTENT">	2188	<div id="AUTHOR_CONTENT">
1217	<p>Marc Lehmann <libev@schmorp.de>.</p>	2189	<p>Marc Lehmann <libev@schmorp.de>.</p>
1218		2190
1219	</div>	2191	</div>
1220	</div></body>	2192	</div></body>
1221	</html>	2193	</html>

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