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4	<head>	4	<head>
5	<title>libev</title>	5	<title>libev</title>
6	<meta name="description" content="Pod documentation for libev" />	6	<meta name="description" content="Pod documentation for libev" />
7	<meta name="inputfile" content="<standard input>" />	7	<meta name="inputfile" content="<standard input>" />
8	<meta name="outputfile" content="<standard output>" />	8	<meta name="outputfile" content="<standard output>" />
9	<meta name="created" content="Sat Nov 24 17:57:37 2007" />	9	<meta name="created" content="Wed Dec 12 18:55:28 2007" />
10	<meta name="generator" content="Pod::Xhtml 1.57" />	10	<meta name="generator" content="Pod::Xhtml 1.57" />
11	<link rel="stylesheet" href="http://res.tst.eu/pod.css"/></head>	11	<link rel="stylesheet" href="http://res.tst.eu/pod.css"/></head>
12	<body>	12	<body>
13	<div class="pod">	13	<div class="pod">
14	<!-- INDEX START -->	14	<!-- INDEX START -->
15	<h3 id="TOP">Index</h3>	15	<h3 id="TOP">Index</h3>
16		16
17	<ul><li><a href="#NAME">NAME</a></li>	17	<ul><li><a href="#NAME">NAME</a></li>
18	<li><a href="#SYNOPSIS">SYNOPSIS</a></li>	18	<li><a href="#SYNOPSIS">SYNOPSIS</a></li>
		19	<li><a href="#EXAMPLE_PROGRAM">EXAMPLE PROGRAM</a></li>
19	<li><a href="#DESCRIPTION">DESCRIPTION</a></li>	20	<li><a href="#DESCRIPTION">DESCRIPTION</a></li>
20	<li><a href="#FEATURES">FEATURES</a></li>	21	<li><a href="#FEATURES">FEATURES</a></li>
21	<li><a href="#CONVENTIONS">CONVENTIONS</a></li>	22	<li><a href="#CONVENTIONS">CONVENTIONS</a></li>
22	<li><a href="#TIME_REPRESENTATION">TIME REPRESENTATION</a></li>	23	<li><a href="#TIME_REPRESENTATION">TIME REPRESENTATION</a></li>
23	<li><a href="#GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</a></li>	24	<li><a href="#GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</a></li>
…		…
26	<ul><li><a href="#GENERIC_WATCHER_FUNCTIONS">GENERIC WATCHER FUNCTIONS</a></li>	27	<ul><li><a href="#GENERIC_WATCHER_FUNCTIONS">GENERIC WATCHER FUNCTIONS</a></li>
27	<li><a href="#ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH">ASSOCIATING CUSTOM DATA WITH A WATCHER</a></li>	28	<li><a href="#ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH">ASSOCIATING CUSTOM DATA WITH A WATCHER</a></li>
28	</ul>	29	</ul>
29	</li>	30	</li>
30	<li><a href="#WATCHER_TYPES">WATCHER TYPES</a>	31	<li><a href="#WATCHER_TYPES">WATCHER TYPES</a>
31	<ul><li><a href="#code_ev_io_code_is_this_file_descrip"><code>ev_io</code> - is this file descriptor readable or writable?</a></li>	32	<ul><li><a href="#code_ev_io_code_is_this_file_descrip"><code>ev_io</code> - is this file descriptor readable or writable?</a>
		33	<ul><li><a href="#The_special_problem_of_disappearing_">The special problem of disappearing file descriptors</a></li>
		34	<li><a href="#Watcher_Specific_Functions">Watcher-Specific Functions</a></li>
		35	</ul>
		36	</li>
32	<li><a href="#code_ev_timer_code_relative_and_opti"><code>ev_timer</code> - relative and optionally repeating timeouts</a></li>	37	<li><a href="#code_ev_timer_code_relative_and_opti"><code>ev_timer</code> - relative and optionally repeating timeouts</a>
		38	<ul><li><a href="#Watcher_Specific_Functions_and_Data_">Watcher-Specific Functions and Data Members</a></li>
		39	</ul>
		40	</li>
33	<li><a href="#code_ev_periodic_code_to_cron_or_not"><code>ev_periodic</code> - to cron or not to cron?</a></li>	41	<li><a href="#code_ev_periodic_code_to_cron_or_not"><code>ev_periodic</code> - to cron or not to cron?</a>
		42	<ul><li><a href="#Watcher_Specific_Functions_and_Data_-3">Watcher-Specific Functions and Data Members</a></li>
		43	</ul>
		44	</li>
34	<li><a href="#code_ev_signal_code_signal_me_when_a"><code>ev_signal</code> - signal me when a signal gets signalled!</a></li>	45	<li><a href="#code_ev_signal_code_signal_me_when_a"><code>ev_signal</code> - signal me when a signal gets signalled!</a>
		46	<ul><li><a href="#Watcher_Specific_Functions_and_Data_-4">Watcher-Specific Functions and Data Members</a></li>
		47	</ul>
		48	</li>
35	<li><a href="#code_ev_child_code_watch_out_for_pro"><code>ev_child</code> - watch out for process status changes</a></li>	49	<li><a href="#code_ev_child_code_watch_out_for_pro"><code>ev_child</code> - watch out for process status changes</a>
		50	<ul><li><a href="#Watcher_Specific_Functions_and_Data_-5">Watcher-Specific Functions and Data Members</a></li>
		51	</ul>
		52	</li>
		53	<li><a href="#code_ev_stat_code_did_the_file_attri"><code>ev_stat</code> - did the file attributes just change?</a>
		54	<ul><li><a href="#Watcher_Specific_Functions_and_Data_-6">Watcher-Specific Functions and Data Members</a></li>
		55	</ul>
		56	</li>
36	<li><a href="#code_ev_idle_code_when_you_ve_got_no"><code>ev_idle</code> - when you've got nothing better to do...</a></li>	57	<li><a href="#code_ev_idle_code_when_you_ve_got_no"><code>ev_idle</code> - when you've got nothing better to do...</a>
		58	<ul><li><a href="#Watcher_Specific_Functions_and_Data_-7">Watcher-Specific Functions and Data Members</a></li>
		59	</ul>
		60	</li>
37	<li><a href="#code_ev_prepare_code_and_code_ev_che"><code>ev_prepare</code> and <code>ev_check</code> - customise your event loop!</a></li>	61	<li><a href="#code_ev_prepare_code_and_code_ev_che"><code>ev_prepare</code> and <code>ev_check</code> - customise your event loop!</a>
		62	<ul><li><a href="#Watcher_Specific_Functions_and_Data_-8">Watcher-Specific Functions and Data Members</a></li>
		63	</ul>
		64	</li>
38	<li><a href="#code_ev_embed_code_when_one_backend_"><code>ev_embed</code> - when one backend isn't enough...</a></li>	65	<li><a href="#code_ev_embed_code_when_one_backend_"><code>ev_embed</code> - when one backend isn't enough...</a>
		66	<ul><li><a href="#Watcher_Specific_Functions_and_Data_-9">Watcher-Specific Functions and Data Members</a></li>
		67	</ul>
		68	</li>
		69	<li><a href="#code_ev_fork_code_the_audacity_to_re"><code>ev_fork</code> - the audacity to resume the event loop after a fork</a>
		70	<ul><li><a href="#Watcher_Specific_Functions_and_Data_-10">Watcher-Specific Functions and Data Members</a></li>
		71	</ul>
		72	</li>
39	</ul>	73	</ul>
40	</li>	74	</li>
41	<li><a href="#OTHER_FUNCTIONS">OTHER FUNCTIONS</a></li>	75	<li><a href="#OTHER_FUNCTIONS">OTHER FUNCTIONS</a></li>
42	<li><a href="#LIBEVENT_EMULATION">LIBEVENT EMULATION</a></li>	76	<li><a href="#LIBEVENT_EMULATION">LIBEVENT EMULATION</a></li>
43	<li><a href="#C_SUPPORT">C++ SUPPORT</a></li>	77	<li><a href="#C_SUPPORT">C++ SUPPORT</a></li>
		78	<li><a href="#MACRO_MAGIC">MACRO MAGIC</a></li>
44	<li><a href="#EMBEDDING">EMBEDDING</a>	79	<li><a href="#EMBEDDING">EMBEDDING</a>
45	<ul><li><a href="#FILESETS">FILESETS</a>	80	<ul><li><a href="#FILESETS">FILESETS</a>
46	<ul><li><a href="#CORE_EVENT_LOOP">CORE EVENT LOOP</a></li>	81	<ul><li><a href="#CORE_EVENT_LOOP">CORE EVENT LOOP</a></li>
47	<li><a href="#LIBEVENT_COMPATIBILITY_API">LIBEVENT COMPATIBILITY API</a></li>	82	<li><a href="#LIBEVENT_COMPATIBILITY_API">LIBEVENT COMPATIBILITY API</a></li>
48	<li><a href="#AUTOCONF_SUPPORT">AUTOCONF SUPPORT</a></li>	83	<li><a href="#AUTOCONF_SUPPORT">AUTOCONF SUPPORT</a></li>
…		…
50	</li>	85	</li>
51	<li><a href="#PREPROCESSOR_SYMBOLS_MACROS">PREPROCESSOR SYMBOLS/MACROS</a></li>	86	<li><a href="#PREPROCESSOR_SYMBOLS_MACROS">PREPROCESSOR SYMBOLS/MACROS</a></li>
52	<li><a href="#EXAMPLES">EXAMPLES</a></li>	87	<li><a href="#EXAMPLES">EXAMPLES</a></li>
53	</ul>	88	</ul>
54	</li>	89	</li>
		90	<li><a href="#COMPLEXITIES">COMPLEXITIES</a></li>
55	<li><a href="#AUTHOR">AUTHOR</a>	91	<li><a href="#AUTHOR">AUTHOR</a>
56	</li>	92	</li>
57	</ul><hr />	93	</ul><hr />
58	<!-- INDEX END -->	94	<!-- INDEX END -->
59		95
60	<h1 id="NAME">NAME</h1><p><a href="#TOP" class="toplink">Top</a></p>	96	<h1 id="NAME">NAME</h1>
61	<div id="NAME_CONTENT">	97	<div id="NAME_CONTENT">
62	<p>libev - a high performance full-featured event loop written in C</p>	98	<p>libev - a high performance full-featured event loop written in C</p>
63		99
64	</div>	100	</div>
65	<h1 id="SYNOPSIS">SYNOPSIS</h1><p><a href="#TOP" class="toplink">Top</a></p>	101	<h1 id="SYNOPSIS">SYNOPSIS</h1>
66	<div id="SYNOPSIS_CONTENT">	102	<div id="SYNOPSIS_CONTENT">
67	<pre> #include <ev.h>	103	<pre> #include <ev.h>
68		104
69	</pre>	105	</pre>
70		106
71	</div>	107	</div>
72	<h1 id="DESCRIPTION">DESCRIPTION</h1><p><a href="#TOP" class="toplink">Top</a></p>	108	<h1 id="EXAMPLE_PROGRAM">EXAMPLE PROGRAM</h1>
		109	<div id="EXAMPLE_PROGRAM_CONTENT">
		110	<pre> #include <ev.h>
		111
		112	ev_io stdin_watcher;
		113	ev_timer timeout_watcher;
		114
		115	/* called when data readable on stdin */
		116	static void
		117	stdin_cb (EV_P_ struct ev_io *w, int revents)
		118	{
		119	/* puts ("stdin ready"); */
		120	ev_io_stop (EV_A_ w); /* just a syntax example */
		121	ev_unloop (EV_A_ EVUNLOOP_ALL); /* leave all loop calls */
		122	}
		123
		124	static void
		125	timeout_cb (EV_P_ struct ev_timer *w, int revents)
		126	{
		127	/* puts ("timeout"); */
		128	ev_unloop (EV_A_ EVUNLOOP_ONE); /* leave one loop call */
		129	}
		130
		131	int
		132	main (void)
		133	{
		134	struct ev_loop *loop = ev_default_loop (0);
		135
		136	/* initialise an io watcher, then start it */
		137	ev_io_init (&stdin_watcher, stdin_cb, /STDIN_FILENO/ 0, EV_READ);
		138	ev_io_start (loop, &stdin_watcher);
		139
		140	/* simple non-repeating 5.5 second timeout */
		141	ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.);
		142	ev_timer_start (loop, &timeout_watcher);
		143
		144	/* loop till timeout or data ready */
		145	ev_loop (loop, 0);
		146
		147	return 0;
		148	}
		149
		150	</pre>
		151
		152	</div>
		153	<h1 id="DESCRIPTION">DESCRIPTION</h1>
73	<div id="DESCRIPTION_CONTENT">	154	<div id="DESCRIPTION_CONTENT">
		155	<p>The newest version of this document is also available as a html-formatted
		156	web page you might find easier to navigate when reading it for the first
		157	time: <a href="http://cvs.schmorp.de/libev/ev.html">http://cvs.schmorp.de/libev/ev.html</a>.</p>
74	<p>Libev is an event loop: you register interest in certain events (such as a	158	<p>Libev is an event loop: you register interest in certain events (such as a
75	file descriptor being readable or a timeout occuring), and it will manage	159	file descriptor being readable or a timeout occuring), and it will manage
76	these event sources and provide your program with events.</p>	160	these event sources and provide your program with events.</p>
77	<p>To do this, it must take more or less complete control over your process	161	<p>To do this, it must take more or less complete control over your process
78	(or thread) by executing the <i>event loop</i> handler, and will then	162	(or thread) by executing the <i>event loop</i> handler, and will then
…		…
81	watchers</i>, which are relatively small C structures you initialise with the	165	watchers</i>, which are relatively small C structures you initialise with the
82	details of the event, and then hand it over to libev by <i>starting</i> the	166	details of the event, and then hand it over to libev by <i>starting</i> the
83	watcher.</p>	167	watcher.</p>
84		168
85	</div>	169	</div>
86	<h1 id="FEATURES">FEATURES</h1><p><a href="#TOP" class="toplink">Top</a></p>	170	<h1 id="FEATURES">FEATURES</h1>
87	<div id="FEATURES_CONTENT">	171	<div id="FEATURES_CONTENT">
88	<p>Libev supports select, poll, the linux-specific epoll and the bsd-specific	172	<p>Libev supports <code>select</code>, <code>poll</code>, the Linux-specific <code>epoll</code>, the
89	kqueue mechanisms for file descriptor events, relative timers, absolute	173	BSD-specific <code>kqueue</code> and the Solaris-specific event port mechanisms
90	timers with customised rescheduling, signal events, process status change	174	for file descriptor events (<code>ev_io</code>), the Linux <code>inotify</code> interface
91	events (related to SIGCHLD), and event watchers dealing with the event	175	(for <code>ev_stat</code>), relative timers (<code>ev_timer</code>), absolute timers
92	loop mechanism itself (idle, prepare and check watchers). It also is quite	176	with customised rescheduling (<code>ev_periodic</code>), synchronous signals
		177	(<code>ev_signal</code>), process status change events (<code>ev_child</code>), and event
		178	watchers dealing with the event loop mechanism itself (<code>ev_idle</code>,
		179	<code>ev_embed</code>, <code>ev_prepare</code> and <code>ev_check</code> watchers) as well as
		180	file watchers (<code>ev_stat</code>) and even limited support for fork events
		181	(<code>ev_fork</code>).</p>
		182	<p>It also is quite fast (see this
93	fast (see this <a href="http://libev.schmorp.de/bench.html">benchmark</a> comparing	183	<a href="http://libev.schmorp.de/bench.html">benchmark</a> comparing it to libevent
94	it to libevent for example).</p>	184	for example).</p>
95		185
96	</div>	186	</div>
97	<h1 id="CONVENTIONS">CONVENTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p>	187	<h1 id="CONVENTIONS">CONVENTIONS</h1>
98	<div id="CONVENTIONS_CONTENT">	188	<div id="CONVENTIONS_CONTENT">
99	<p>Libev is very configurable. In this manual the default configuration	189	<p>Libev is very configurable. In this manual the default configuration will
100	will be described, which supports multiple event loops. For more info	190	be described, which supports multiple event loops. For more info about
101	about various configuration options please have a look at the file	191	various configuration options please have a look at <strong>EMBED</strong> section in
102	<cite>README.embed</cite> in the libev distribution. If libev was configured without	192	this manual. If libev was configured without support for multiple event
103	support for multiple event loops, then all functions taking an initial	193	loops, then all functions taking an initial argument of name <code>loop</code>
104	argument of name <code>loop</code> (which is always of type <code>struct ev_loop *</code>)	194	(which is always of type <code>struct ev_loop *</code>) will not have this argument.</p>
105	will not have this argument.</p>
106		195
107	</div>	196	</div>
108	<h1 id="TIME_REPRESENTATION">TIME REPRESENTATION</h1><p><a href="#TOP" class="toplink">Top</a></p>	197	<h1 id="TIME_REPRESENTATION">TIME REPRESENTATION</h1>
109	<div id="TIME_REPRESENTATION_CONTENT">	198	<div id="TIME_REPRESENTATION_CONTENT">
110	<p>Libev represents time as a single floating point number, representing the	199	<p>Libev represents time as a single floating point number, representing the
111	(fractional) number of seconds since the (POSIX) epoch (somewhere near	200	(fractional) number of seconds since the (POSIX) epoch (somewhere near
112	the beginning of 1970, details are complicated, don't ask). This type is	201	the beginning of 1970, details are complicated, don't ask). This type is
113	called <code>ev_tstamp</code>, which is what you should use too. It usually aliases	202	called <code>ev_tstamp</code>, which is what you should use too. It usually aliases
114	to the <code>double</code> type in C, and when you need to do any calculations on	203	to the <code>double</code> type in C, and when you need to do any calculations on
115	it, you should treat it as such.</p>	204	it, you should treat it as such.</p>
116		205
117
118
119
120
121	</div>	206	</div>
122	<h1 id="GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p>	207	<h1 id="GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</h1>
123	<div id="GLOBAL_FUNCTIONS_CONTENT">	208	<div id="GLOBAL_FUNCTIONS_CONTENT">
124	<p>These functions can be called anytime, even before initialising the	209	<p>These functions can be called anytime, even before initialising the
125	library in any way.</p>	210	library in any way.</p>
126	<dl>	211	<dl>
127	<dt>ev_tstamp ev_time ()</dt>	212	<dt>ev_tstamp ev_time ()</dt>
…		…
131	you actually want to know.</p>	216	you actually want to know.</p>
132	</dd>	217	</dd>
133	<dt>int ev_version_major ()</dt>	218	<dt>int ev_version_major ()</dt>
134	<dt>int ev_version_minor ()</dt>	219	<dt>int ev_version_minor ()</dt>
135	<dd>	220	<dd>
136	<p>You can find out the major and minor version numbers of the library	221	<p>You can find out the major and minor ABI version numbers of the library
137	you linked against by calling the functions <code>ev_version_major</code> and	222	you linked against by calling the functions <code>ev_version_major</code> and
138	<code>ev_version_minor</code>. If you want, you can compare against the global	223	<code>ev_version_minor</code>. If you want, you can compare against the global
139	symbols <code>EV_VERSION_MAJOR</code> and <code>EV_VERSION_MINOR</code>, which specify the	224	symbols <code>EV_VERSION_MAJOR</code> and <code>EV_VERSION_MINOR</code>, which specify the
140	version of the library your program was compiled against.</p>	225	version of the library your program was compiled against.</p>
		226	<p>These version numbers refer to the ABI version of the library, not the
		227	release version.</p>
141	<p>Usually, it's a good idea to terminate if the major versions mismatch,	228	<p>Usually, it's a good idea to terminate if the major versions mismatch,
142	as this indicates an incompatible change. Minor versions are usually	229	as this indicates an incompatible change. Minor versions are usually
143	compatible to older versions, so a larger minor version alone is usually	230	compatible to older versions, so a larger minor version alone is usually
144	not a problem.</p>	231	not a problem.</p>
145	<p>Example: make sure we haven't accidentally been linked against the wrong	232	<p>Example: Make sure we haven't accidentally been linked against the wrong
146	version:</p>	233	version.</p>
147	<pre> assert (("libev version mismatch",	234	<pre> assert (("libev version mismatch",
148	ev_version_major () == EV_VERSION_MAJOR	235	ev_version_major () == EV_VERSION_MAJOR
149	&& ev_version_minor () >= EV_VERSION_MINOR));	236	&& ev_version_minor () >= EV_VERSION_MINOR));
150		237
151	</pre>	238	</pre>
…		…
181	recommended ones.</p>	268	recommended ones.</p>
182	<p>See the description of <code>ev_embed</code> watchers for more info.</p>	269	<p>See the description of <code>ev_embed</code> watchers for more info.</p>
183	</dd>	270	</dd>
184	<dt>ev_set_allocator (void (cb)(void *ptr, long size))</dt>	271	<dt>ev_set_allocator (void (cb)(void *ptr, long size))</dt>
185	<dd>	272	<dd>
186	<p>Sets the allocation function to use (the prototype is similar to the	273	<p>Sets the allocation function to use (the prototype is similar - the
187	realloc C function, the semantics are identical). It is used to allocate	274	semantics is identical - to the realloc C function). It is used to
188	and free memory (no surprises here). If it returns zero when memory	275	allocate and free memory (no surprises here). If it returns zero when
189	needs to be allocated, the library might abort or take some potentially	276	memory needs to be allocated, the library might abort or take some
190	destructive action. The default is your system realloc function.</p>	277	potentially destructive action. The default is your system realloc
		278	function.</p>
191	<p>You could override this function in high-availability programs to, say,	279	<p>You could override this function in high-availability programs to, say,
192	free some memory if it cannot allocate memory, to use a special allocator,	280	free some memory if it cannot allocate memory, to use a special allocator,
193	or even to sleep a while and retry until some memory is available.</p>	281	or even to sleep a while and retry until some memory is available.</p>
194	<p>Example: replace the libev allocator with one that waits a bit and then	282	<p>Example: Replace the libev allocator with one that waits a bit and then
195	retries: better than mine).</p>	283	retries).</p>
196	<pre> static void *	284	<pre> static void *
197	persistent_realloc (void *ptr, long size)	285	persistent_realloc (void *ptr, size_t size)
198	{	286	{
199	for (;;)	287	for (;;)
200	{	288	{
201	void *newptr = realloc (ptr, size);	289	void *newptr = realloc (ptr, size);
202		290
…		…
219	indicating the system call or subsystem causing the problem. If this	307	indicating the system call or subsystem causing the problem. If this
220	callback is set, then libev will expect it to remedy the sitution, no	308	callback is set, then libev will expect it to remedy the sitution, no
221	matter what, when it returns. That is, libev will generally retry the	309	matter what, when it returns. That is, libev will generally retry the
222	requested operation, or, if the condition doesn't go away, do bad stuff	310	requested operation, or, if the condition doesn't go away, do bad stuff
223	(such as abort).</p>	311	(such as abort).</p>
224	<p>Example: do the same thing as libev does internally:</p>	312	<p>Example: This is basically the same thing that libev does internally, too.</p>
225	<pre> static void	313	<pre> static void
226	fatal_error (const char *msg)	314	fatal_error (const char *msg)
227	{	315	{
228	perror (msg);	316	perror (msg);
229	abort ();	317	abort ();
…		…
235	</pre>	323	</pre>
236	</dd>	324	</dd>
237	</dl>	325	</dl>
238		326
239	</div>	327	</div>
240	<h1 id="FUNCTIONS_CONTROLLING_THE_EVENT_LOOP">FUNCTIONS CONTROLLING THE EVENT LOOP</h1><p><a href="#TOP" class="toplink">Top</a></p>	328	<h1 id="FUNCTIONS_CONTROLLING_THE_EVENT_LOOP">FUNCTIONS CONTROLLING THE EVENT LOOP</h1>
241	<div id="FUNCTIONS_CONTROLLING_THE_EVENT_LOOP-2">	329	<div id="FUNCTIONS_CONTROLLING_THE_EVENT_LOOP-2">
242	<p>An event loop is described by a <code>struct ev_loop *</code>. The library knows two	330	<p>An event loop is described by a <code>struct ev_loop *</code>. The library knows two
243	types of such loops, the <i>default</i> loop, which supports signals and child	331	types of such loops, the <i>default</i> loop, which supports signals and child
244	events, and dynamically created loops which do not.</p>	332	events, and dynamically created loops which do not.</p>
245	<p>If you use threads, a common model is to run the default event loop	333	<p>If you use threads, a common model is to run the default event loop
…		…
274	<code>LIBEV_FLAGS</code>. Otherwise (the default), this environment variable will	362	<code>LIBEV_FLAGS</code>. Otherwise (the default), this environment variable will
275	override the flags completely if it is found in the environment. This is	363	override the flags completely if it is found in the environment. This is
276	useful to try out specific backends to test their performance, or to work	364	useful to try out specific backends to test their performance, or to work
277	around bugs.</p>	365	around bugs.</p>
278	</dd>	366	</dd>
		367	<dt><code>EVFLAG_FORKCHECK</code></dt>
		368	<dd>
		369	<p>Instead of calling <code>ev_default_fork</code> or <code>ev_loop_fork</code> manually after
		370	a fork, you can also make libev check for a fork in each iteration by
		371	enabling this flag.</p>
		372	<p>This works by calling <code>getpid ()</code> on every iteration of the loop,
		373	and thus this might slow down your event loop if you do a lot of loop
		374	iterations and little real work, but is usually not noticeable (on my
		375	Linux system for example, <code>getpid</code> is actually a simple 5-insn sequence
		376	without a syscall and thus <i>very</i> fast, but my Linux system also has
		377	<code>pthread_atfork</code> which is even faster).</p>
		378	<p>The big advantage of this flag is that you can forget about fork (and
		379	forget about forgetting to tell libev about forking) when you use this
		380	flag.</p>
		381	<p>This flag setting cannot be overriden or specified in the <code>LIBEV_FLAGS</code>
		382	environment variable.</p>
		383	</dd>
279	<dt><code>EVBACKEND_SELECT</code> (value 1, portable select backend)</dt>	384	<dt><code>EVBACKEND_SELECT</code> (value 1, portable select backend)</dt>
280	<dd>	385	<dd>
281	<p>This is your standard select(2) backend. Not <i>completely</i> standard, as	386	<p>This is your standard select(2) backend. Not <i>completely</i> standard, as
282	libev tries to roll its own fd_set with no limits on the number of fds,	387	libev tries to roll its own fd_set with no limits on the number of fds,
283	but if that fails, expect a fairly low limit on the number of fds when	388	but if that fails, expect a fairly low limit on the number of fds when
…		…
365	<dd>	470	<dd>
366	<p>Similar to <code>ev_default_loop</code>, but always creates a new event loop that is	471	<p>Similar to <code>ev_default_loop</code>, but always creates a new event loop that is
367	always distinct from the default loop. Unlike the default loop, it cannot	472	always distinct from the default loop. Unlike the default loop, it cannot
368	handle signal and child watchers, and attempts to do so will be greeted by	473	handle signal and child watchers, and attempts to do so will be greeted by
369	undefined behaviour (or a failed assertion if assertions are enabled).</p>	474	undefined behaviour (or a failed assertion if assertions are enabled).</p>
370	<p>Example: try to create a event loop that uses epoll and nothing else.</p>	475	<p>Example: Try to create a event loop that uses epoll and nothing else.</p>
371	<pre> struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL \| EVFLAG_NOENV);	476	<pre> struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL \| EVFLAG_NOENV);
372	if (!epoller)	477	if (!epoller)
373	fatal ("no epoll found here, maybe it hides under your chair");	478	fatal ("no epoll found here, maybe it hides under your chair");
374		479
375	</pre>	480	</pre>
…		…
411	<dt>ev_loop_fork (loop)</dt>	516	<dt>ev_loop_fork (loop)</dt>
412	<dd>	517	<dd>
413	<p>Like <code>ev_default_fork</code>, but acts on an event loop created by	518	<p>Like <code>ev_default_fork</code>, but acts on an event loop created by
414	<code>ev_loop_new</code>. Yes, you have to call this on every allocated event loop	519	<code>ev_loop_new</code>. Yes, you have to call this on every allocated event loop
415	after fork, and how you do this is entirely your own problem.</p>	520	after fork, and how you do this is entirely your own problem.</p>
		521	</dd>
		522	<dt>unsigned int ev_loop_count (loop)</dt>
		523	<dd>
		524	<p>Returns the count of loop iterations for the loop, which is identical to
		525	the number of times libev did poll for new events. It starts at <code>0</code> and
		526	happily wraps around with enough iterations.</p>
		527	<p>This value can sometimes be useful as a generation counter of sorts (it
		528	"ticks" the number of loop iterations), as it roughly corresponds with
		529	<code>ev_prepare</code> and <code>ev_check</code> calls.</p>
416	</dd>	530	</dd>
417	<dt>unsigned int ev_backend (loop)</dt>	531	<dt>unsigned int ev_backend (loop)</dt>
418	<dd>	532	<dd>
419	<p>Returns one of the <code>EVBACKEND_*</code> flags indicating the event backend in	533	<p>Returns one of the <code>EVBACKEND_*</code> flags indicating the event backend in
420	use.</p>	534	use.</p>
…		…
448	one iteration of the loop. This is useful if you are waiting for some	562	one iteration of the loop. This is useful if you are waiting for some
449	external event in conjunction with something not expressible using other	563	external event in conjunction with something not expressible using other
450	libev watchers. However, a pair of <code>ev_prepare</code>/<code>ev_check</code> watchers is	564	libev watchers. However, a pair of <code>ev_prepare</code>/<code>ev_check</code> watchers is
451	usually a better approach for this kind of thing.</p>	565	usually a better approach for this kind of thing.</p>
452	<p>Here are the gory details of what <code>ev_loop</code> does:</p>	566	<p>Here are the gory details of what <code>ev_loop</code> does:</p>
		567	<pre> - Before the first iteration, call any pending watchers.
453	<pre> * If there are no active watchers (reference count is zero), return.	568	* If there are no active watchers (reference count is zero), return.
454	- Queue prepare watchers and then call all outstanding watchers.	569	- Queue all prepare watchers and then call all outstanding watchers.
455	- If we have been forked, recreate the kernel state.	570	- If we have been forked, recreate the kernel state.
456	- Update the kernel state with all outstanding changes.	571	- Update the kernel state with all outstanding changes.
457	- Update the "event loop time".	572	- Update the "event loop time".
458	- Calculate for how long to block.	573	- Calculate for how long to block.
459	- Block the process, waiting for any events.	574	- Block the process, waiting for any events.
…		…
468	be handled here by queueing them when their watcher gets executed.	583	be handled here by queueing them when their watcher gets executed.
469	- If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK	584	- If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK
470	were used, return, otherwise continue with step *.	585	were used, return, otherwise continue with step *.
471		586
472	</pre>	587	</pre>
473	<p>Example: queue some jobs and then loop until no events are outsanding	588	<p>Example: Queue some jobs and then loop until no events are outsanding
474	anymore.</p>	589	anymore.</p>
475	<pre> ... queue jobs here, make sure they register event watchers as long	590	<pre> ... queue jobs here, make sure they register event watchers as long
476	... as they still have work to do (even an idle watcher will do..)	591	... as they still have work to do (even an idle watcher will do..)
477	ev_loop (my_loop, 0);	592	ev_loop (my_loop, 0);
478	... jobs done. yeah!	593	... jobs done. yeah!
…		…
497	example, libev itself uses this for its internal signal pipe: It is not	612	example, libev itself uses this for its internal signal pipe: It is not
498	visible to the libev user and should not keep <code>ev_loop</code> from exiting if	613	visible to the libev user and should not keep <code>ev_loop</code> from exiting if
499	no event watchers registered by it are active. It is also an excellent	614	no event watchers registered by it are active. It is also an excellent
500	way to do this for generic recurring timers or from within third-party	615	way to do this for generic recurring timers or from within third-party
501	libraries. Just remember to <i>unref after start</i> and <i>ref before stop</i>.</p>	616	libraries. Just remember to <i>unref after start</i> and <i>ref before stop</i>.</p>
502	<p>Example: create a signal watcher, but keep it from keeping <code>ev_loop</code>	617	<p>Example: Create a signal watcher, but keep it from keeping <code>ev_loop</code>
503	running when nothing else is active.</p>	618	running when nothing else is active.</p>
504	<pre> struct dv_signal exitsig;	619	<pre> struct ev_signal exitsig;
505	ev_signal_init (&exitsig, sig_cb, SIGINT);	620	ev_signal_init (&exitsig, sig_cb, SIGINT);
506	ev_signal_start (myloop, &exitsig);	621	ev_signal_start (loop, &exitsig);
507	evf_unref (myloop);	622	evf_unref (loop);
508		623
509	</pre>	624	</pre>
510	<p>Example: for some weird reason, unregister the above signal handler again.</p>	625	<p>Example: For some weird reason, unregister the above signal handler again.</p>
511	<pre> ev_ref (myloop);	626	<pre> ev_ref (loop);
512	ev_signal_stop (myloop, &exitsig);	627	ev_signal_stop (loop, &exitsig);
513		628
514	</pre>	629	</pre>
515	</dd>	630	</dd>
516	</dl>	631	</dl>
517		632
518		633
519		634
520		635
521		636
522	</div>	637	</div>
523	<h1 id="ANATOMY_OF_A_WATCHER">ANATOMY OF A WATCHER</h1><p><a href="#TOP" class="toplink">Top</a></p>	638	<h1 id="ANATOMY_OF_A_WATCHER">ANATOMY OF A WATCHER</h1>
524	<div id="ANATOMY_OF_A_WATCHER_CONTENT">	639	<div id="ANATOMY_OF_A_WATCHER_CONTENT">
525	<p>A watcher is a structure that you create and register to record your	640	<p>A watcher is a structure that you create and register to record your
526	interest in some event. For instance, if you want to wait for STDIN to	641	interest in some event. For instance, if you want to wait for STDIN to
527	become readable, you would create an <code>ev_io</code> watcher for that:</p>	642	become readable, you would create an <code>ev_io</code> watcher for that:</p>
528	<pre> static void my_cb (struct ev_loop loop, struct ev_io w, int revents)	643	<pre> static void my_cb (struct ev_loop loop, struct ev_io w, int revents)
…		…
585	</dd>	700	</dd>
586	<dt><code>EV_CHILD</code></dt>	701	<dt><code>EV_CHILD</code></dt>
587	<dd>	702	<dd>
588	<p>The pid specified in the <code>ev_child</code> watcher has received a status change.</p>	703	<p>The pid specified in the <code>ev_child</code> watcher has received a status change.</p>
589	</dd>	704	</dd>
		705	<dt><code>EV_STAT</code></dt>
		706	<dd>
		707	<p>The path specified in the <code>ev_stat</code> watcher changed its attributes somehow.</p>
		708	</dd>
590	<dt><code>EV_IDLE</code></dt>	709	<dt><code>EV_IDLE</code></dt>
591	<dd>	710	<dd>
592	<p>The <code>ev_idle</code> watcher has determined that you have nothing better to do.</p>	711	<p>The <code>ev_idle</code> watcher has determined that you have nothing better to do.</p>
593	</dd>	712	</dd>
594	<dt><code>EV_PREPARE</code></dt>	713	<dt><code>EV_PREPARE</code></dt>
…		…
599	<code>ev_loop</code> has gathered them, but before it invokes any callbacks for any	718	<code>ev_loop</code> has gathered them, but before it invokes any callbacks for any
600	received events. Callbacks of both watcher types can start and stop as	719	received events. Callbacks of both watcher types can start and stop as
601	many watchers as they want, and all of them will be taken into account	720	many watchers as they want, and all of them will be taken into account
602	(for example, a <code>ev_prepare</code> watcher might start an idle watcher to keep	721	(for example, a <code>ev_prepare</code> watcher might start an idle watcher to keep
603	<code>ev_loop</code> from blocking).</p>	722	<code>ev_loop</code> from blocking).</p>
		723	</dd>
		724	<dt><code>EV_EMBED</code></dt>
		725	<dd>
		726	<p>The embedded event loop specified in the <code>ev_embed</code> watcher needs attention.</p>
		727	</dd>
		728	<dt><code>EV_FORK</code></dt>
		729	<dd>
		730	<p>The event loop has been resumed in the child process after fork (see
		731	<code>ev_fork</code>).</p>
604	</dd>	732	</dd>
605	<dt><code>EV_ERROR</code></dt>	733	<dt><code>EV_ERROR</code></dt>
606	<dd>	734	<dd>
607	<p>An unspecified error has occured, the watcher has been stopped. This might	735	<p>An unspecified error has occured, the watcher has been stopped. This might
608	happen because the watcher could not be properly started because libev	736	happen because the watcher could not be properly started because libev
…		…
675	<dt>bool ev_is_pending (ev_TYPE *watcher)</dt>	803	<dt>bool ev_is_pending (ev_TYPE *watcher)</dt>
676	<dd>	804	<dd>
677	<p>Returns a true value iff the watcher is pending, (i.e. it has outstanding	805	<p>Returns a true value iff the watcher is pending, (i.e. it has outstanding
678	events but its callback has not yet been invoked). As long as a watcher	806	events but its callback has not yet been invoked). As long as a watcher
679	is pending (but not active) you must not call an init function on it (but	807	is pending (but not active) you must not call an init function on it (but
680	<code>ev_TYPE_set</code> is safe) and you must make sure the watcher is available to	808	<code>ev_TYPE_set</code> is safe), you must not change its priority, and you must
681	libev (e.g. you cnanot <code>free ()</code> it).</p>	809	make sure the watcher is available to libev (e.g. you cannot <code>free ()</code>
		810	it).</p>
682	</dd>	811	</dd>
683	<dt>callback = ev_cb (ev_TYPE *watcher)</dt>	812	<dt>callback ev_cb (ev_TYPE *watcher)</dt>
684	<dd>	813	<dd>
685	<p>Returns the callback currently set on the watcher.</p>	814	<p>Returns the callback currently set on the watcher.</p>
686	</dd>	815	</dd>
687	<dt>ev_cb_set (ev_TYPE *watcher, callback)</dt>	816	<dt>ev_cb_set (ev_TYPE *watcher, callback)</dt>
688	<dd>	817	<dd>
689	<p>Change the callback. You can change the callback at virtually any time	818	<p>Change the callback. You can change the callback at virtually any time
690	(modulo threads).</p>	819	(modulo threads).</p>
		820	</dd>
		821	<dt>ev_set_priority (ev_TYPE *watcher, priority)</dt>
		822	<dt>int ev_priority (ev_TYPE *watcher)</dt>
		823	<dd>
		824	<p>Set and query the priority of the watcher. The priority is a small
		825	integer between <code>EV_MAXPRI</code> (default: <code>2</code>) and <code>EV_MINPRI</code>
		826	(default: <code>-2</code>). Pending watchers with higher priority will be invoked
		827	before watchers with lower priority, but priority will not keep watchers
		828	from being executed (except for <code>ev_idle</code> watchers).</p>
		829	<p>This means that priorities are <i>only</i> used for ordering callback
		830	invocation after new events have been received. This is useful, for
		831	example, to reduce latency after idling, or more often, to bind two
		832	watchers on the same event and make sure one is called first.</p>
		833	<p>If you need to suppress invocation when higher priority events are pending
		834	you need to look at <code>ev_idle</code> watchers, which provide this functionality.</p>
		835	<p>You <i>must not</i> change the priority of a watcher as long as it is active or
		836	pending.</p>
		837	<p>The default priority used by watchers when no priority has been set is
		838	always <code>0</code>, which is supposed to not be too high and not be too low :).</p>
		839	<p>Setting a priority outside the range of <code>EV_MINPRI</code> to <code>EV_MAXPRI</code> is
		840	fine, as long as you do not mind that the priority value you query might
		841	or might not have been adjusted to be within valid range.</p>
		842	</dd>
		843	<dt>ev_invoke (loop, ev_TYPE *watcher, int revents)</dt>
		844	<dd>
		845	<p>Invoke the <code>watcher</code> with the given <code>loop</code> and <code>revents</code>. Neither
		846	<code>loop</code> nor <code>revents</code> need to be valid as long as the watcher callback
		847	can deal with that fact.</p>
		848	</dd>
		849	<dt>int ev_clear_pending (loop, ev_TYPE *watcher)</dt>
		850	<dd>
		851	<p>If the watcher is pending, this function returns clears its pending status
		852	and returns its <code>revents</code> bitset (as if its callback was invoked). If the
		853	watcher isn't pending it does nothing and returns <code>0</code>.</p>
691	</dd>	854	</dd>
692	</dl>	855	</dl>
693		856
694		857
695		858
…		…
720	struct my_io w = (struct my_io )w_;	883	struct my_io w = (struct my_io )w_;
721	...	884	...
722	}	885	}
723		886
724	</pre>	887	</pre>
725	<p>More interesting and less C-conformant ways of catsing your callback type	888	<p>More interesting and less C-conformant ways of casting your callback type
726	have been omitted....</p>	889	instead have been omitted.</p>
		890	<p>Another common scenario is having some data structure with multiple
		891	watchers:</p>
		892	<pre> struct my_biggy
		893	{
		894	int some_data;
		895	ev_timer t1;
		896	ev_timer t2;
		897	}
727		898
		899	</pre>
		900	<p>In this case getting the pointer to <code>my_biggy</code> is a bit more complicated,
		901	you need to use <code>offsetof</code>:</p>
		902	<pre> #include <stddef.h>
728		903
		904	static void
		905	t1_cb (EV_P_ struct ev_timer *w, int revents)
		906	{
		907	struct my_biggy big = (struct my_biggy *
		908	(((char *)w) - offsetof (struct my_biggy, t1));
		909	}
729		910
		911	static void
		912	t2_cb (EV_P_ struct ev_timer *w, int revents)
		913	{
		914	struct my_biggy big = (struct my_biggy *
		915	(((char *)w) - offsetof (struct my_biggy, t2));
		916	}
730		917
731		918
		919
		920
		921	</pre>
		922
732	</div>	923	</div>
733	<h1 id="WATCHER_TYPES">WATCHER TYPES</h1><p><a href="#TOP" class="toplink">Top</a></p>	924	<h1 id="WATCHER_TYPES">WATCHER TYPES</h1>
734	<div id="WATCHER_TYPES_CONTENT">	925	<div id="WATCHER_TYPES_CONTENT">
735	<p>This section describes each watcher in detail, but will not repeat	926	<p>This section describes each watcher in detail, but will not repeat
736	information given in the last section.</p>	927	information given in the last section. Any initialisation/set macros,
		928	functions and members specific to the watcher type are explained.</p>
		929	<p>Members are additionally marked with either <i>[read-only]</i>, meaning that,
		930	while the watcher is active, you can look at the member and expect some
		931	sensible content, but you must not modify it (you can modify it while the
		932	watcher is stopped to your hearts content), or <i>[read-write]</i>, which
		933	means you can expect it to have some sensible content while the watcher
		934	is active, but you can also modify it. Modifying it may not do something
		935	sensible or take immediate effect (or do anything at all), but libev will
		936	not crash or malfunction in any way.</p>
737		937
738		938
739		939
740		940
741		941
…		…
769	this situation even with a relatively standard program structure. Thus	969	this situation even with a relatively standard program structure. Thus
770	it is best to always use non-blocking I/O: An extra <code>read</code>(2) returning	970	it is best to always use non-blocking I/O: An extra <code>read</code>(2) returning
771	<code>EAGAIN</code> is far preferable to a program hanging until some data arrives.</p>	971	<code>EAGAIN</code> is far preferable to a program hanging until some data arrives.</p>
772	<p>If you cannot run the fd in non-blocking mode (for example you should not	972	<p>If you cannot run the fd in non-blocking mode (for example you should not
773	play around with an Xlib connection), then you have to seperately re-test	973	play around with an Xlib connection), then you have to seperately re-test
774	wether a file descriptor is really ready with a known-to-be good interface	974	whether a file descriptor is really ready with a known-to-be good interface
775	such as poll (fortunately in our Xlib example, Xlib already does this on	975	such as poll (fortunately in our Xlib example, Xlib already does this on
776	its own, so its quite safe to use).</p>	976	its own, so its quite safe to use).</p>
		977
		978	</div>
		979	<h3 id="The_special_problem_of_disappearing_">The special problem of disappearing file descriptors</h3>
		980	<div id="The_special_problem_of_disappearing_-2">
		981	<p>Some backends (e.g kqueue, epoll) need to be told about closing a file
		982	descriptor (either by calling <code>close</code> explicitly or by any other means,
		983	such as <code>dup</code>). The reason is that you register interest in some file
		984	descriptor, but when it goes away, the operating system will silently drop
		985	this interest. If another file descriptor with the same number then is
		986	registered with libev, there is no efficient way to see that this is, in
		987	fact, a different file descriptor.</p>
		988	<p>To avoid having to explicitly tell libev about such cases, libev follows
		989	the following policy: Each time <code>ev_io_set</code> is being called, libev
		990	will assume that this is potentially a new file descriptor, otherwise
		991	it is assumed that the file descriptor stays the same. That means that
		992	you <i>have</i> to call <code>ev_io_set</code> (or <code>ev_io_init</code>) when you change the
		993	descriptor even if the file descriptor number itself did not change.</p>
		994	<p>This is how one would do it normally anyway, the important point is that
		995	the libev application should not optimise around libev but should leave
		996	optimisations to libev.</p>
		997
		998
		999
		1000
		1001
		1002	</div>
		1003	<h3 id="Watcher_Specific_Functions">Watcher-Specific Functions</h3>
		1004	<div id="Watcher_Specific_Functions_CONTENT">
777	<dl>	1005	<dl>
778	<dt>ev_io_init (ev_io *, callback, int fd, int events)</dt>	1006	<dt>ev_io_init (ev_io *, callback, int fd, int events)</dt>
779	<dt>ev_io_set (ev_io *, int fd, int events)</dt>	1007	<dt>ev_io_set (ev_io *, int fd, int events)</dt>
780	<dd>	1008	<dd>
781	<p>Configures an <code>ev_io</code> watcher. The <code>fd</code> is the file descriptor to	1009	<p>Configures an <code>ev_io</code> watcher. The <code>fd</code> is the file descriptor to
782	rceeive events for and events is either <code>EV_READ</code>, <code>EV_WRITE</code> or	1010	rceeive events for and events is either <code>EV_READ</code>, <code>EV_WRITE</code> or
783	<code>EV_READ \| EV_WRITE</code> to receive the given events.</p>	1011	<code>EV_READ \| EV_WRITE</code> to receive the given events.</p>
784	</dd>	1012	</dd>
		1013	<dt>int fd [read-only]</dt>
		1014	<dd>
		1015	<p>The file descriptor being watched.</p>
		1016	</dd>
		1017	<dt>int events [read-only]</dt>
		1018	<dd>
		1019	<p>The events being watched.</p>
		1020	</dd>
785	</dl>	1021	</dl>
786	<p>Example: call <code>stdin_readable_cb</code> when STDIN_FILENO has become, well	1022	<p>Example: Call <code>stdin_readable_cb</code> when STDIN_FILENO has become, well
787	readable, but only once. Since it is likely line-buffered, you could	1023	readable, but only once. Since it is likely line-buffered, you could
788	attempt to read a whole line in the callback:</p>	1024	attempt to read a whole line in the callback.</p>
789	<pre> static void	1025	<pre> static void
790	stdin_readable_cb (struct ev_loop loop, struct ev_io w, int revents)	1026	stdin_readable_cb (struct ev_loop loop, struct ev_io w, int revents)
791	{	1027	{
792	ev_io_stop (loop, w);	1028	ev_io_stop (loop, w);
793	.. read from stdin here (or from w->fd) and haqndle any I/O errors	1029	.. read from stdin here (or from w->fd) and haqndle any I/O errors
…		…
824		1060
825	</pre>	1061	</pre>
826	<p>The callback is guarenteed to be invoked only when its timeout has passed,	1062	<p>The callback is guarenteed to be invoked only when its timeout has passed,
827	but if multiple timers become ready during the same loop iteration then	1063	but if multiple timers become ready during the same loop iteration then
828	order of execution is undefined.</p>	1064	order of execution is undefined.</p>
		1065
		1066	</div>
		1067	<h3 id="Watcher_Specific_Functions_and_Data_">Watcher-Specific Functions and Data Members</h3>
		1068	<div id="Watcher_Specific_Functions_and_Data_-2">
829	<dl>	1069	<dl>
830	<dt>ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)</dt>	1070	<dt>ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)</dt>
831	<dt>ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)</dt>	1071	<dt>ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)</dt>
832	<dd>	1072	<dd>
833	<p>Configure the timer to trigger after <code>after</code> seconds. If <code>repeat</code> is	1073	<p>Configure the timer to trigger after <code>after</code> seconds. If <code>repeat</code> is
…		…
842	</dd>	1082	</dd>
843	<dt>ev_timer_again (loop)</dt>	1083	<dt>ev_timer_again (loop)</dt>
844	<dd>	1084	<dd>
845	<p>This will act as if the timer timed out and restart it again if it is	1085	<p>This will act as if the timer timed out and restart it again if it is
846	repeating. The exact semantics are:</p>	1086	repeating. The exact semantics are:</p>
		1087	<p>If the timer is pending, its pending status is cleared.</p>
847	<p>If the timer is started but nonrepeating, stop it.</p>	1088	<p>If the timer is started but nonrepeating, stop it (as if it timed out).</p>
848	<p>If the timer is repeating, either start it if necessary (with the repeat	1089	<p>If the timer is repeating, either start it if necessary (with the
849	value), or reset the running timer to the repeat value.</p>	1090	<code>repeat</code> value), or reset the running timer to the <code>repeat</code> value.</p>
850	<p>This sounds a bit complicated, but here is a useful and typical	1091	<p>This sounds a bit complicated, but here is a useful and typical
851	example: Imagine you have a tcp connection and you want a so-called idle	1092	example: Imagine you have a tcp connection and you want a so-called idle
852	timeout, that is, you want to be called when there have been, say, 60	1093	timeout, that is, you want to be called when there have been, say, 60
853	seconds of inactivity on the socket. The easiest way to do this is to	1094	seconds of inactivity on the socket. The easiest way to do this is to
854	configure an <code>ev_timer</code> with after=repeat=60 and calling ev_timer_again each	1095	configure an <code>ev_timer</code> with a <code>repeat</code> value of <code>60</code> and then call
855	time you successfully read or write some data. If you go into an idle	1096	<code>ev_timer_again</code> each time you successfully read or write some data. If
856	state where you do not expect data to travel on the socket, you can stop	1097	you go into an idle state where you do not expect data to travel on the
		1098	socket, you can <code>ev_timer_stop</code> the timer, and <code>ev_timer_again</code> will
857	the timer, and again will automatically restart it if need be.</p>	1099	automatically restart it if need be.</p>
		1100	<p>That means you can ignore the <code>after</code> value and <code>ev_timer_start</code>
		1101	altogether and only ever use the <code>repeat</code> value and <code>ev_timer_again</code>:</p>
		1102	<pre> ev_timer_init (timer, callback, 0., 5.);
		1103	ev_timer_again (loop, timer);
		1104	...
		1105	timer->again = 17.;
		1106	ev_timer_again (loop, timer);
		1107	...
		1108	timer->again = 10.;
		1109	ev_timer_again (loop, timer);
		1110
		1111	</pre>
		1112	<p>This is more slightly efficient then stopping/starting the timer each time
		1113	you want to modify its timeout value.</p>
		1114	</dd>
		1115	<dt>ev_tstamp repeat [read-write]</dt>
		1116	<dd>
		1117	<p>The current <code>repeat</code> value. Will be used each time the watcher times out
		1118	or <code>ev_timer_again</code> is called and determines the next timeout (if any),
		1119	which is also when any modifications are taken into account.</p>
858	</dd>	1120	</dd>
859	</dl>	1121	</dl>
860	<p>Example: create a timer that fires after 60 seconds.</p>	1122	<p>Example: Create a timer that fires after 60 seconds.</p>
861	<pre> static void	1123	<pre> static void
862	one_minute_cb (struct ev_loop loop, struct ev_timer w, int revents)	1124	one_minute_cb (struct ev_loop loop, struct ev_timer w, int revents)
863	{	1125	{
864	.. one minute over, w is actually stopped right here	1126	.. one minute over, w is actually stopped right here
865	}	1127	}
…		…
867	struct ev_timer mytimer;	1129	struct ev_timer mytimer;
868	ev_timer_init (&mytimer, one_minute_cb, 60., 0.);	1130	ev_timer_init (&mytimer, one_minute_cb, 60., 0.);
869	ev_timer_start (loop, &mytimer);	1131	ev_timer_start (loop, &mytimer);
870		1132
871	</pre>	1133	</pre>
872	<p>Example: create a timeout timer that times out after 10 seconds of	1134	<p>Example: Create a timeout timer that times out after 10 seconds of
873	inactivity.</p>	1135	inactivity.</p>
874	<pre> static void	1136	<pre> static void
875	timeout_cb (struct ev_loop loop, struct ev_timer w, int revents)	1137	timeout_cb (struct ev_loop loop, struct ev_timer w, int revents)
876	{	1138	{
877	.. ten seconds without any activity	1139	.. ten seconds without any activity
…		…
900	but on wallclock time (absolute time). You can tell a periodic watcher	1162	but on wallclock time (absolute time). You can tell a periodic watcher
901	to trigger "at" some specific point in time. For example, if you tell a	1163	to trigger "at" some specific point in time. For example, if you tell a
902	periodic watcher to trigger in 10 seconds (by specifiying e.g. <code>ev_now ()	1164	periodic watcher to trigger in 10 seconds (by specifiying e.g. <code>ev_now ()
903	+ 10.</code>) and then reset your system clock to the last year, then it will	1165	+ 10.</code>) and then reset your system clock to the last year, then it will
904	take a year to trigger the event (unlike an <code>ev_timer</code>, which would trigger	1166	take a year to trigger the event (unlike an <code>ev_timer</code>, which would trigger
905	roughly 10 seconds later and of course not if you reset your system time	1167	roughly 10 seconds later).</p>
906	again).</p>
907	<p>They can also be used to implement vastly more complex timers, such as	1168	<p>They can also be used to implement vastly more complex timers, such as
908	triggering an event on eahc midnight, local time.</p>	1169	triggering an event on each midnight, local time or other, complicated,
		1170	rules.</p>
909	<p>As with timers, the callback is guarenteed to be invoked only when the	1171	<p>As with timers, the callback is guarenteed to be invoked only when the
910	time (<code>at</code>) has been passed, but if multiple periodic timers become ready	1172	time (<code>at</code>) has been passed, but if multiple periodic timers become ready
911	during the same loop iteration then order of execution is undefined.</p>	1173	during the same loop iteration then order of execution is undefined.</p>
		1174
		1175	</div>
		1176	<h3 id="Watcher_Specific_Functions_and_Data_-3">Watcher-Specific Functions and Data Members</h3>
		1177	<div id="Watcher_Specific_Functions_and_Data_-2">
912	<dl>	1178	<dl>
913	<dt>ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)</dt>	1179	<dt>ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)</dt>
914	<dt>ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)</dt>	1180	<dt>ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)</dt>
915	<dd>	1181	<dd>
916	<p>Lots of arguments, lets sort it out... There are basically three modes of	1182	<p>Lots of arguments, lets sort it out... There are basically three modes of
917	operation, and we will explain them from simplest to complex:</p>	1183	operation, and we will explain them from simplest to complex:</p>
918	<p>	1184	<p>
919	<dl>	1185	<dl>
920	<dt>* absolute timer (interval = reschedule_cb = 0)</dt>	1186	<dt>* absolute timer (at = time, interval = reschedule_cb = 0)</dt>
921	<dd>	1187	<dd>
922	<p>In this configuration the watcher triggers an event at the wallclock time	1188	<p>In this configuration the watcher triggers an event at the wallclock time
923	<code>at</code> and doesn't repeat. It will not adjust when a time jump occurs,	1189	<code>at</code> and doesn't repeat. It will not adjust when a time jump occurs,
924	that is, if it is to be run at January 1st 2011 then it will run when the	1190	that is, if it is to be run at January 1st 2011 then it will run when the
925	system time reaches or surpasses this time.</p>	1191	system time reaches or surpasses this time.</p>
926	</dd>	1192	</dd>
927	<dt>* non-repeating interval timer (interval > 0, reschedule_cb = 0)</dt>	1193	<dt>* non-repeating interval timer (at = offset, interval > 0, reschedule_cb = 0)</dt>
928	<dd>	1194	<dd>
929	<p>In this mode the watcher will always be scheduled to time out at the next	1195	<p>In this mode the watcher will always be scheduled to time out at the next
930	<code>at + N * interval</code> time (for some integer N) and then repeat, regardless	1196	<code>at + N * interval</code> time (for some integer N, which can also be negative)
931	of any time jumps.</p>	1197	and then repeat, regardless of any time jumps.</p>
932	<p>This can be used to create timers that do not drift with respect to system	1198	<p>This can be used to create timers that do not drift with respect to system
933	time:</p>	1199	time:</p>
934	<pre> ev_periodic_set (&periodic, 0., 3600., 0);	1200	<pre> ev_periodic_set (&periodic, 0., 3600., 0);
935		1201
936	</pre>	1202	</pre>
…		…
939	full hour (UTC), or more correctly, when the system time is evenly divisible	1205	full hour (UTC), or more correctly, when the system time is evenly divisible
940	by 3600.</p>	1206	by 3600.</p>
941	<p>Another way to think about it (for the mathematically inclined) is that	1207	<p>Another way to think about it (for the mathematically inclined) is that
942	<code>ev_periodic</code> will try to run the callback in this mode at the next possible	1208	<code>ev_periodic</code> will try to run the callback in this mode at the next possible
943	time where <code>time = at (mod interval)</code>, regardless of any time jumps.</p>	1209	time where <code>time = at (mod interval)</code>, regardless of any time jumps.</p>
		1210	<p>For numerical stability it is preferable that the <code>at</code> value is near
		1211	<code>ev_now ()</code> (the current time), but there is no range requirement for
		1212	this value.</p>
944	</dd>	1213	</dd>
945	<dt>* manual reschedule mode (reschedule_cb = callback)</dt>	1214	<dt>* manual reschedule mode (at and interval ignored, reschedule_cb = callback)</dt>
946	<dd>	1215	<dd>
947	<p>In this mode the values for <code>interval</code> and <code>at</code> are both being	1216	<p>In this mode the values for <code>interval</code> and <code>at</code> are both being
948	ignored. Instead, each time the periodic watcher gets scheduled, the	1217	ignored. Instead, each time the periodic watcher gets scheduled, the
949	reschedule callback will be called with the watcher as first, and the	1218	reschedule callback will be called with the watcher as first, and the
950	current time as second argument.</p>	1219	current time as second argument.</p>
951	<p>NOTE: <i>This callback MUST NOT stop or destroy any periodic watcher,	1220	<p>NOTE: <i>This callback MUST NOT stop or destroy any periodic watcher,
952	ever, or make any event loop modifications</i>. If you need to stop it,	1221	ever, or make any event loop modifications</i>. If you need to stop it,
953	return <code>now + 1e30</code> (or so, fudge fudge) and stop it afterwards (e.g. by	1222	return <code>now + 1e30</code> (or so, fudge fudge) and stop it afterwards (e.g. by
954	starting a prepare watcher).</p>	1223	starting an <code>ev_prepare</code> watcher, which is legal).</p>
955	<p>Its prototype is <code>ev_tstamp (reschedule_cb)(struct ev_periodic w,	1224	<p>Its prototype is <code>ev_tstamp (reschedule_cb)(struct ev_periodic w,
956	ev_tstamp now)</code>, e.g.:</p>	1225	ev_tstamp now)</code>, e.g.:</p>
957	<pre> static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now)	1226	<pre> static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now)
958	{	1227	{
959	return now + 60.;	1228	return now + 60.;
…		…
980	<p>Simply stops and restarts the periodic watcher again. This is only useful	1249	<p>Simply stops and restarts the periodic watcher again. This is only useful
981	when you changed some parameters or the reschedule callback would return	1250	when you changed some parameters or the reschedule callback would return
982	a different time than the last time it was called (e.g. in a crond like	1251	a different time than the last time it was called (e.g. in a crond like
983	program when the crontabs have changed).</p>	1252	program when the crontabs have changed).</p>
984	</dd>	1253	</dd>
		1254	<dt>ev_tstamp offset [read-write]</dt>
		1255	<dd>
		1256	<p>When repeating, this contains the offset value, otherwise this is the
		1257	absolute point in time (the <code>at</code> value passed to <code>ev_periodic_set</code>).</p>
		1258	<p>Can be modified any time, but changes only take effect when the periodic
		1259	timer fires or <code>ev_periodic_again</code> is being called.</p>
		1260	</dd>
		1261	<dt>ev_tstamp interval [read-write]</dt>
		1262	<dd>
		1263	<p>The current interval value. Can be modified any time, but changes only
		1264	take effect when the periodic timer fires or <code>ev_periodic_again</code> is being
		1265	called.</p>
		1266	</dd>
		1267	<dt>ev_tstamp (reschedule_cb)(struct ev_periodic w, ev_tstamp now) [read-write]</dt>
		1268	<dd>
		1269	<p>The current reschedule callback, or <code>0</code>, if this functionality is
		1270	switched off. Can be changed any time, but changes only take effect when
		1271	the periodic timer fires or <code>ev_periodic_again</code> is being called.</p>
		1272	</dd>
985	</dl>	1273	</dl>
986	<p>Example: call a callback every hour, or, more precisely, whenever the	1274	<p>Example: Call a callback every hour, or, more precisely, whenever the
987	system clock is divisible by 3600. The callback invocation times have	1275	system clock is divisible by 3600. The callback invocation times have
988	potentially a lot of jittering, but good long-term stability.</p>	1276	potentially a lot of jittering, but good long-term stability.</p>
989	<pre> static void	1277	<pre> static void
990	clock_cb (struct ev_loop loop, struct ev_io w, int revents)	1278	clock_cb (struct ev_loop loop, struct ev_io w, int revents)
991	{	1279	{
…		…
995	struct ev_periodic hourly_tick;	1283	struct ev_periodic hourly_tick;
996	ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);	1284	ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);
997	ev_periodic_start (loop, &hourly_tick);	1285	ev_periodic_start (loop, &hourly_tick);
998		1286
999	</pre>	1287	</pre>
1000	<p>Example: the same as above, but use a reschedule callback to do it:</p>	1288	<p>Example: The same as above, but use a reschedule callback to do it:</p>
1001	<pre> #include <math.h>	1289	<pre> #include <math.h>
1002		1290
1003	static ev_tstamp	1291	static ev_tstamp
1004	my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)	1292	my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)
1005	{	1293	{
…		…
1007	}	1295	}
1008		1296
1009	ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);	1297	ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);
1010		1298
1011	</pre>	1299	</pre>
1012	<p>Example: call a callback every hour, starting now:</p>	1300	<p>Example: Call a callback every hour, starting now:</p>
1013	<pre> struct ev_periodic hourly_tick;	1301	<pre> struct ev_periodic hourly_tick;
1014	ev_periodic_init (&hourly_tick, clock_cb,	1302	ev_periodic_init (&hourly_tick, clock_cb,
1015	fmod (ev_now (loop), 3600.), 3600., 0);	1303	fmod (ev_now (loop), 3600.), 3600., 0);
1016	ev_periodic_start (loop, &hourly_tick);	1304	ev_periodic_start (loop, &hourly_tick);
1017		1305
…		…
1031	first watcher gets started will libev actually register a signal watcher	1319	first watcher gets started will libev actually register a signal watcher
1032	with the kernel (thus it coexists with your own signal handlers as long	1320	with the kernel (thus it coexists with your own signal handlers as long
1033	as you don't register any with libev). Similarly, when the last signal	1321	as you don't register any with libev). Similarly, when the last signal
1034	watcher for a signal is stopped libev will reset the signal handler to	1322	watcher for a signal is stopped libev will reset the signal handler to
1035	SIG_DFL (regardless of what it was set to before).</p>	1323	SIG_DFL (regardless of what it was set to before).</p>
		1324
		1325	</div>
		1326	<h3 id="Watcher_Specific_Functions_and_Data_-4">Watcher-Specific Functions and Data Members</h3>
		1327	<div id="Watcher_Specific_Functions_and_Data_-2-2">
1036	<dl>	1328	<dl>
1037	<dt>ev_signal_init (ev_signal *, callback, int signum)</dt>	1329	<dt>ev_signal_init (ev_signal *, callback, int signum)</dt>
1038	<dt>ev_signal_set (ev_signal *, int signum)</dt>	1330	<dt>ev_signal_set (ev_signal *, int signum)</dt>
1039	<dd>	1331	<dd>
1040	<p>Configures the watcher to trigger on the given signal number (usually one	1332	<p>Configures the watcher to trigger on the given signal number (usually one
1041	of the <code>SIGxxx</code> constants).</p>	1333	of the <code>SIGxxx</code> constants).</p>
		1334	</dd>
		1335	<dt>int signum [read-only]</dt>
		1336	<dd>
		1337	<p>The signal the watcher watches out for.</p>
1042	</dd>	1338	</dd>
1043	</dl>	1339	</dl>
1044		1340
1045		1341
1046		1342
…		…
1049	</div>	1345	</div>
1050	<h2 id="code_ev_child_code_watch_out_for_pro"><code>ev_child</code> - watch out for process status changes</h2>	1346	<h2 id="code_ev_child_code_watch_out_for_pro"><code>ev_child</code> - watch out for process status changes</h2>
1051	<div id="code_ev_child_code_watch_out_for_pro-2">	1347	<div id="code_ev_child_code_watch_out_for_pro-2">
1052	<p>Child watchers trigger when your process receives a SIGCHLD in response to	1348	<p>Child watchers trigger when your process receives a SIGCHLD in response to
1053	some child status changes (most typically when a child of yours dies).</p>	1349	some child status changes (most typically when a child of yours dies).</p>
		1350
		1351	</div>
		1352	<h3 id="Watcher_Specific_Functions_and_Data_-5">Watcher-Specific Functions and Data Members</h3>
		1353	<div id="Watcher_Specific_Functions_and_Data_-2-3">
1054	<dl>	1354	<dl>
1055	<dt>ev_child_init (ev_child *, callback, int pid)</dt>	1355	<dt>ev_child_init (ev_child *, callback, int pid)</dt>
1056	<dt>ev_child_set (ev_child *, int pid)</dt>	1356	<dt>ev_child_set (ev_child *, int pid)</dt>
1057	<dd>	1357	<dd>
1058	<p>Configures the watcher to wait for status changes of process <code>pid</code> (or	1358	<p>Configures the watcher to wait for status changes of process <code>pid</code> (or
…		…
1060	at the <code>rstatus</code> member of the <code>ev_child</code> watcher structure to see	1360	at the <code>rstatus</code> member of the <code>ev_child</code> watcher structure to see
1061	the status word (use the macros from <code>sys/wait.h</code> and see your systems	1361	the status word (use the macros from <code>sys/wait.h</code> and see your systems
1062	<code>waitpid</code> documentation). The <code>rpid</code> member contains the pid of the	1362	<code>waitpid</code> documentation). The <code>rpid</code> member contains the pid of the
1063	process causing the status change.</p>	1363	process causing the status change.</p>
1064	</dd>	1364	</dd>
		1365	<dt>int pid [read-only]</dt>
		1366	<dd>
		1367	<p>The process id this watcher watches out for, or <code>0</code>, meaning any process id.</p>
		1368	</dd>
		1369	<dt>int rpid [read-write]</dt>
		1370	<dd>
		1371	<p>The process id that detected a status change.</p>
		1372	</dd>
		1373	<dt>int rstatus [read-write]</dt>
		1374	<dd>
		1375	<p>The process exit/trace status caused by <code>rpid</code> (see your systems
		1376	<code>waitpid</code> and <code>sys/wait.h</code> documentation for details).</p>
		1377	</dd>
1065	</dl>	1378	</dl>
1066	<p>Example: try to exit cleanly on SIGINT and SIGTERM.</p>	1379	<p>Example: Try to exit cleanly on SIGINT and SIGTERM.</p>
1067	<pre> static void	1380	<pre> static void
1068	sigint_cb (struct ev_loop loop, struct ev_signal w, int revents)	1381	sigint_cb (struct ev_loop loop, struct ev_signal w, int revents)
1069	{	1382	{
1070	ev_unloop (loop, EVUNLOOP_ALL);	1383	ev_unloop (loop, EVUNLOOP_ALL);
1071	}	1384	}
…		…
1078		1391
1079		1392
1080	</pre>	1393	</pre>
1081		1394
1082	</div>	1395	</div>
		1396	<h2 id="code_ev_stat_code_did_the_file_attri"><code>ev_stat</code> - did the file attributes just change?</h2>
		1397	<div id="code_ev_stat_code_did_the_file_attri-2">
		1398	<p>This watches a filesystem path for attribute changes. That is, it calls
		1399	<code>stat</code> regularly (or when the OS says it changed) and sees if it changed
		1400	compared to the last time, invoking the callback if it did.</p>
		1401	<p>The path does not need to exist: changing from "path exists" to "path does
		1402	not exist" is a status change like any other. The condition "path does
		1403	not exist" is signified by the <code>st_nlink</code> field being zero (which is
		1404	otherwise always forced to be at least one) and all the other fields of
		1405	the stat buffer having unspecified contents.</p>
		1406	<p>The path <i>should</i> be absolute and <i>must not</i> end in a slash. If it is
		1407	relative and your working directory changes, the behaviour is undefined.</p>
		1408	<p>Since there is no standard to do this, the portable implementation simply
		1409	calls <code>stat (2)</code> regularly on the path to see if it changed somehow. You
		1410	can specify a recommended polling interval for this case. If you specify
		1411	a polling interval of <code>0</code> (highly recommended!) then a <i>suitable,
		1412	unspecified default</i> value will be used (which you can expect to be around
		1413	five seconds, although this might change dynamically). Libev will also
		1414	impose a minimum interval which is currently around <code>0.1</code>, but thats
		1415	usually overkill.</p>
		1416	<p>This watcher type is not meant for massive numbers of stat watchers,
		1417	as even with OS-supported change notifications, this can be
		1418	resource-intensive.</p>
		1419	<p>At the time of this writing, only the Linux inotify interface is
		1420	implemented (implementing kqueue support is left as an exercise for the
		1421	reader). Inotify will be used to give hints only and should not change the
		1422	semantics of <code>ev_stat</code> watchers, which means that libev sometimes needs
		1423	to fall back to regular polling again even with inotify, but changes are
		1424	usually detected immediately, and if the file exists there will be no
		1425	polling.</p>
		1426
		1427	</div>
		1428	<h3 id="Watcher_Specific_Functions_and_Data_-6">Watcher-Specific Functions and Data Members</h3>
		1429	<div id="Watcher_Specific_Functions_and_Data_-2-4">
		1430	<dl>
		1431	<dt>ev_stat_init (ev_stat , callback, const char path, ev_tstamp interval)</dt>
		1432	<dt>ev_stat_set (ev_stat , const char path, ev_tstamp interval)</dt>
		1433	<dd>
		1434	<p>Configures the watcher to wait for status changes of the given
		1435	<code>path</code>. The <code>interval</code> is a hint on how quickly a change is expected to
		1436	be detected and should normally be specified as <code>0</code> to let libev choose
		1437	a suitable value. The memory pointed to by <code>path</code> must point to the same
		1438	path for as long as the watcher is active.</p>
		1439	<p>The callback will be receive <code>EV_STAT</code> when a change was detected,
		1440	relative to the attributes at the time the watcher was started (or the
		1441	last change was detected).</p>
		1442	</dd>
		1443	<dt>ev_stat_stat (ev_stat *)</dt>
		1444	<dd>
		1445	<p>Updates the stat buffer immediately with new values. If you change the
		1446	watched path in your callback, you could call this fucntion to avoid
		1447	detecting this change (while introducing a race condition). Can also be
		1448	useful simply to find out the new values.</p>
		1449	</dd>
		1450	<dt>ev_statdata attr [read-only]</dt>
		1451	<dd>
		1452	<p>The most-recently detected attributes of the file. Although the type is of
		1453	<code>ev_statdata</code>, this is usually the (or one of the) <code>struct stat</code> types
		1454	suitable for your system. If the <code>st_nlink</code> member is <code>0</code>, then there
		1455	was some error while <code>stat</code>ing the file.</p>
		1456	</dd>
		1457	<dt>ev_statdata prev [read-only]</dt>
		1458	<dd>
		1459	<p>The previous attributes of the file. The callback gets invoked whenever
		1460	<code>prev</code> != <code>attr</code>.</p>
		1461	</dd>
		1462	<dt>ev_tstamp interval [read-only]</dt>
		1463	<dd>
		1464	<p>The specified interval.</p>
		1465	</dd>
		1466	<dt>const char *path [read-only]</dt>
		1467	<dd>
		1468	<p>The filesystem path that is being watched.</p>
		1469	</dd>
		1470	</dl>
		1471	<p>Example: Watch <code>/etc/passwd</code> for attribute changes.</p>
		1472	<pre> static void
		1473	passwd_cb (struct ev_loop loop, ev_stat w, int revents)
		1474	{
		1475	/* /etc/passwd changed in some way */
		1476	if (w->attr.st_nlink)
		1477	{
		1478	printf ("passwd current size %ld\n", (long)w->attr.st_size);
		1479	printf ("passwd current atime %ld\n", (long)w->attr.st_mtime);
		1480	printf ("passwd current mtime %ld\n", (long)w->attr.st_mtime);
		1481	}
		1482	else
		1483	/* you shalt not abuse printf for puts */
		1484	puts ("wow, /etc/passwd is not there, expect problems. "
		1485	"if this is windows, they already arrived\n");
		1486	}
		1487
		1488	...
		1489	ev_stat passwd;
		1490
		1491	ev_stat_init (&passwd, passwd_cb, "/etc/passwd");
		1492	ev_stat_start (loop, &passwd);
		1493
		1494
		1495
		1496
		1497	</pre>
		1498
		1499	</div>
1083	<h2 id="code_ev_idle_code_when_you_ve_got_no"><code>ev_idle</code> - when you've got nothing better to do...</h2>	1500	<h2 id="code_ev_idle_code_when_you_ve_got_no"><code>ev_idle</code> - when you've got nothing better to do...</h2>
1084	<div id="code_ev_idle_code_when_you_ve_got_no-2">	1501	<div id="code_ev_idle_code_when_you_ve_got_no-2">
1085	<p>Idle watchers trigger events when there are no other events are pending	1502	<p>Idle watchers trigger events when no other events of the same or higher
1086	(prepare, check and other idle watchers do not count). That is, as long	1503	priority are pending (prepare, check and other idle watchers do not
1087	as your process is busy handling sockets or timeouts (or even signals,	1504	count).</p>
1088	imagine) it will not be triggered. But when your process is idle all idle	1505	<p>That is, as long as your process is busy handling sockets or timeouts
1089	watchers are being called again and again, once per event loop iteration -	1506	(or even signals, imagine) of the same or higher priority it will not be
		1507	triggered. But when your process is idle (or only lower-priority watchers
		1508	are pending), the idle watchers are being called once per event loop
1090	until stopped, that is, or your process receives more events and becomes	1509	iteration - until stopped, that is, or your process receives more events
1091	busy.</p>	1510	and becomes busy again with higher priority stuff.</p>
1092	<p>The most noteworthy effect is that as long as any idle watchers are	1511	<p>The most noteworthy effect is that as long as any idle watchers are
1093	active, the process will not block when waiting for new events.</p>	1512	active, the process will not block when waiting for new events.</p>
1094	<p>Apart from keeping your process non-blocking (which is a useful	1513	<p>Apart from keeping your process non-blocking (which is a useful
1095	effect on its own sometimes), idle watchers are a good place to do	1514	effect on its own sometimes), idle watchers are a good place to do
1096	"pseudo-background processing", or delay processing stuff to after the	1515	"pseudo-background processing", or delay processing stuff to after the
1097	event loop has handled all outstanding events.</p>	1516	event loop has handled all outstanding events.</p>
		1517
		1518	</div>
		1519	<h3 id="Watcher_Specific_Functions_and_Data_-7">Watcher-Specific Functions and Data Members</h3>
		1520	<div id="Watcher_Specific_Functions_and_Data_-2-5">
1098	<dl>	1521	<dl>
1099	<dt>ev_idle_init (ev_signal *, callback)</dt>	1522	<dt>ev_idle_init (ev_signal *, callback)</dt>
1100	<dd>	1523	<dd>
1101	<p>Initialises and configures the idle watcher - it has no parameters of any	1524	<p>Initialises and configures the idle watcher - it has no parameters of any
1102	kind. There is a <code>ev_idle_set</code> macro, but using it is utterly pointless,	1525	kind. There is a <code>ev_idle_set</code> macro, but using it is utterly pointless,
1103	believe me.</p>	1526	believe me.</p>
1104	</dd>	1527	</dd>
1105	</dl>	1528	</dl>
1106	<p>Example: dynamically allocate an <code>ev_idle</code>, start it, and in the	1529	<p>Example: Dynamically allocate an <code>ev_idle</code> watcher, start it, and in the
1107	callback, free it. Alos, use no error checking, as usual.</p>	1530	callback, free it. Also, use no error checking, as usual.</p>
1108	<pre> static void	1531	<pre> static void
1109	idle_cb (struct ev_loop loop, struct ev_idle w, int revents)	1532	idle_cb (struct ev_loop loop, struct ev_idle w, int revents)
1110	{	1533	{
1111	free (w);	1534	free (w);
1112	// now do something you wanted to do when the program has	1535	// now do something you wanted to do when the program has
…		…
1126	<h2 id="code_ev_prepare_code_and_code_ev_che"><code>ev_prepare</code> and <code>ev_check</code> - customise your event loop!</h2>	1549	<h2 id="code_ev_prepare_code_and_code_ev_che"><code>ev_prepare</code> and <code>ev_check</code> - customise your event loop!</h2>
1127	<div id="code_ev_prepare_code_and_code_ev_che-2">	1550	<div id="code_ev_prepare_code_and_code_ev_che-2">
1128	<p>Prepare and check watchers are usually (but not always) used in tandem:	1551	<p>Prepare and check watchers are usually (but not always) used in tandem:
1129	prepare watchers get invoked before the process blocks and check watchers	1552	prepare watchers get invoked before the process blocks and check watchers
1130	afterwards.</p>	1553	afterwards.</p>
		1554	<p>You <i>must not</i> call <code>ev_loop</code> or similar functions that enter
		1555	the current event loop from either <code>ev_prepare</code> or <code>ev_check</code>
		1556	watchers. Other loops than the current one are fine, however. The
		1557	rationale behind this is that you do not need to check for recursion in
		1558	those watchers, i.e. the sequence will always be <code>ev_prepare</code>, blocking,
		1559	<code>ev_check</code> so if you have one watcher of each kind they will always be
		1560	called in pairs bracketing the blocking call.</p>
1131	<p>Their main purpose is to integrate other event mechanisms into libev and	1561	<p>Their main purpose is to integrate other event mechanisms into libev and
1132	their use is somewhat advanced. This could be used, for example, to track	1562	their use is somewhat advanced. This could be used, for example, to track
1133	variable changes, implement your own watchers, integrate net-snmp or a	1563	variable changes, implement your own watchers, integrate net-snmp or a
1134	coroutine library and lots more.</p>	1564	coroutine library and lots more. They are also occasionally useful if
		1565	you cache some data and want to flush it before blocking (for example,
		1566	in X programs you might want to do an <code>XFlush ()</code> in an <code>ev_prepare</code>
		1567	watcher).</p>
1135	<p>This is done by examining in each prepare call which file descriptors need	1568	<p>This is done by examining in each prepare call which file descriptors need
1136	to be watched by the other library, registering <code>ev_io</code> watchers for	1569	to be watched by the other library, registering <code>ev_io</code> watchers for
1137	them and starting an <code>ev_timer</code> watcher for any timeouts (many libraries	1570	them and starting an <code>ev_timer</code> watcher for any timeouts (many libraries
1138	provide just this functionality). Then, in the check watcher you check for	1571	provide just this functionality). Then, in the check watcher you check for
1139	any events that occured (by checking the pending status of all watchers	1572	any events that occured (by checking the pending status of all watchers
…		…
1146	are ready to run (it's actually more complicated: it only runs coroutines	1579	are ready to run (it's actually more complicated: it only runs coroutines
1147	with priority higher than or equal to the event loop and one coroutine	1580	with priority higher than or equal to the event loop and one coroutine
1148	of lower priority, but only once, using idle watchers to keep the event	1581	of lower priority, but only once, using idle watchers to keep the event
1149	loop from blocking if lower-priority coroutines are active, thus mapping	1582	loop from blocking if lower-priority coroutines are active, thus mapping
1150	low-priority coroutines to idle/background tasks).</p>	1583	low-priority coroutines to idle/background tasks).</p>
		1584	<p>It is recommended to give <code>ev_check</code> watchers highest (<code>EV_MAXPRI</code>)
		1585	priority, to ensure that they are being run before any other watchers
		1586	after the poll. Also, <code>ev_check</code> watchers (and <code>ev_prepare</code> watchers,
		1587	too) should not activate ("feed") events into libev. While libev fully
		1588	supports this, they will be called before other <code>ev_check</code> watchers did
		1589	their job. As <code>ev_check</code> watchers are often used to embed other event
		1590	loops those other event loops might be in an unusable state until their
		1591	<code>ev_check</code> watcher ran (always remind yourself to coexist peacefully with
		1592	others).</p>
		1593
		1594	</div>
		1595	<h3 id="Watcher_Specific_Functions_and_Data_-8">Watcher-Specific Functions and Data Members</h3>
		1596	<div id="Watcher_Specific_Functions_and_Data_-2-6">
1151	<dl>	1597	<dl>
1152	<dt>ev_prepare_init (ev_prepare *, callback)</dt>	1598	<dt>ev_prepare_init (ev_prepare *, callback)</dt>
1153	<dt>ev_check_init (ev_check *, callback)</dt>	1599	<dt>ev_check_init (ev_check *, callback)</dt>
1154	<dd>	1600	<dd>
1155	<p>Initialises and configures the prepare or check watcher - they have no	1601	<p>Initialises and configures the prepare or check watcher - they have no
1156	parameters of any kind. There are <code>ev_prepare_set</code> and <code>ev_check_set</code>	1602	parameters of any kind. There are <code>ev_prepare_set</code> and <code>ev_check_set</code>
1157	macros, but using them is utterly, utterly and completely pointless.</p>	1603	macros, but using them is utterly, utterly and completely pointless.</p>
1158	</dd>	1604	</dd>
1159	</dl>	1605	</dl>
1160	<p>Example: TODO.</p>	1606	<p>There are a number of principal ways to embed other event loops or modules
		1607	into libev. Here are some ideas on how to include libadns into libev
		1608	(there is a Perl module named <code>EV::ADNS</code> that does this, which you could
		1609	use for an actually working example. Another Perl module named <code>EV::Glib</code>
		1610	embeds a Glib main context into libev, and finally, <code>Glib::EV</code> embeds EV
		1611	into the Glib event loop).</p>
		1612	<p>Method 1: Add IO watchers and a timeout watcher in a prepare handler,
		1613	and in a check watcher, destroy them and call into libadns. What follows
		1614	is pseudo-code only of course. This requires you to either use a low
		1615	priority for the check watcher or use <code>ev_clear_pending</code> explicitly, as
		1616	the callbacks for the IO/timeout watchers might not have been called yet.</p>
		1617	<pre> static ev_io iow [nfd];
		1618	static ev_timer tw;
1161		1619
		1620	static void
		1621	io_cb (ev_loop loop, ev_io w, int revents)
		1622	{
		1623	}
1162		1624
		1625	// create io watchers for each fd and a timer before blocking
		1626	static void
		1627	adns_prepare_cb (ev_loop loop, ev_prepare w, int revents)
		1628	{
		1629	int timeout = 3600000;
		1630	struct pollfd fds [nfd];
		1631	// actual code will need to loop here and realloc etc.
		1632	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));
1163		1633
		1634	/* the callback is illegal, but won't be called as we stop during check */
		1635	ev_timer_init (&tw, 0, timeout * 1e-3);
		1636	ev_timer_start (loop, &tw);
1164		1637
		1638	// create one ev_io per pollfd
		1639	for (int i = 0; i < nfd; ++i)
		1640	{
		1641	ev_io_init (iow + i, io_cb, fds [i].fd,
		1642	((fds [i].events & POLLIN ? EV_READ : 0)
		1643	\| (fds [i].events & POLLOUT ? EV_WRITE : 0)));
		1644
		1645	fds [i].revents = 0;
		1646	ev_io_start (loop, iow + i);
		1647	}
		1648	}
		1649
		1650	// stop all watchers after blocking
		1651	static void
		1652	adns_check_cb (ev_loop loop, ev_check w, int revents)
		1653	{
		1654	ev_timer_stop (loop, &tw);
		1655
		1656	for (int i = 0; i < nfd; ++i)
		1657	{
		1658	// set the relevant poll flags
		1659	// could also call adns_processreadable etc. here
		1660	struct pollfd *fd = fds + i;
		1661	int revents = ev_clear_pending (iow + i);
		1662	if (revents & EV_READ ) fd->revents \|= fd->events & POLLIN;
		1663	if (revents & EV_WRITE) fd->revents \|= fd->events & POLLOUT;
		1664
		1665	// now stop the watcher
		1666	ev_io_stop (loop, iow + i);
		1667	}
		1668
		1669	adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));
		1670	}
		1671
		1672	</pre>
		1673	<p>Method 2: This would be just like method 1, but you run <code>adns_afterpoll</code>
		1674	in the prepare watcher and would dispose of the check watcher.</p>
		1675	<p>Method 3: If the module to be embedded supports explicit event
		1676	notification (adns does), you can also make use of the actual watcher
		1677	callbacks, and only destroy/create the watchers in the prepare watcher.</p>
		1678	<pre> static void
		1679	timer_cb (EV_P_ ev_timer *w, int revents)
		1680	{
		1681	adns_state ads = (adns_state)w->data;
		1682	update_now (EV_A);
		1683
		1684	adns_processtimeouts (ads, &tv_now);
		1685	}
		1686
		1687	static void
		1688	io_cb (EV_P_ ev_io *w, int revents)
		1689	{
		1690	adns_state ads = (adns_state)w->data;
		1691	update_now (EV_A);
		1692
		1693	if (revents & EV_READ ) adns_processreadable (ads, w->fd, &tv_now);
		1694	if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now);
		1695	}
		1696
		1697	// do not ever call adns_afterpoll
		1698
		1699	</pre>
		1700	<p>Method 4: Do not use a prepare or check watcher because the module you
		1701	want to embed is too inflexible to support it. Instead, youc na override
		1702	their poll function. The drawback with this solution is that the main
		1703	loop is now no longer controllable by EV. The <code>Glib::EV</code> module does
		1704	this.</p>
		1705	<pre> static gint
		1706	event_poll_func (GPollFD *fds, guint nfds, gint timeout)
		1707	{
		1708	int got_events = 0;
		1709
		1710	for (n = 0; n < nfds; ++n)
		1711	// create/start io watcher that sets the relevant bits in fds[n] and increment got_events
		1712
		1713	if (timeout >= 0)
		1714	// create/start timer
		1715
		1716	// poll
		1717	ev_loop (EV_A_ 0);
		1718
		1719	// stop timer again
		1720	if (timeout >= 0)
		1721	ev_timer_stop (EV_A_ &to);
		1722
		1723	// stop io watchers again - their callbacks should have set
		1724	for (n = 0; n < nfds; ++n)
		1725	ev_io_stop (EV_A_ iow [n]);
		1726
		1727	return got_events;
		1728	}
		1729
		1730
		1731
		1732
		1733	</pre>
1165		1734
1166	</div>	1735	</div>
1167	<h2 id="code_ev_embed_code_when_one_backend_"><code>ev_embed</code> - when one backend isn't enough...</h2>	1736	<h2 id="code_ev_embed_code_when_one_backend_"><code>ev_embed</code> - when one backend isn't enough...</h2>
1168	<div id="code_ev_embed_code_when_one_backend_-2">	1737	<div id="code_ev_embed_code_when_one_backend_-2">
1169	<p>This is a rather advanced watcher type that lets you embed one event loop	1738	<p>This is a rather advanced watcher type that lets you embed one event loop
…		…
1224	}	1793	}
1225	else	1794	else
1226	loop_lo = loop_hi;	1795	loop_lo = loop_hi;
1227		1796
1228	</pre>	1797	</pre>
		1798
		1799	</div>
		1800	<h3 id="Watcher_Specific_Functions_and_Data_-9">Watcher-Specific Functions and Data Members</h3>
		1801	<div id="Watcher_Specific_Functions_and_Data_-2-7">
1229	<dl>	1802	<dl>
1230	<dt>ev_embed_init (ev_embed , callback, struct ev_loop embedded_loop)</dt>	1803	<dt>ev_embed_init (ev_embed , callback, struct ev_loop embedded_loop)</dt>
1231	<dt>ev_embed_set (ev_embed , callback, struct ev_loop embedded_loop)</dt>	1804	<dt>ev_embed_set (ev_embed , callback, struct ev_loop embedded_loop)</dt>
1232	<dd>	1805	<dd>
1233	<p>Configures the watcher to embed the given loop, which must be	1806	<p>Configures the watcher to embed the given loop, which must be
…		…
1240	<dd>	1813	<dd>
1241	<p>Make a single, non-blocking sweep over the embedded loop. This works	1814	<p>Make a single, non-blocking sweep over the embedded loop. This works
1242	similarly to <code>ev_loop (embedded_loop, EVLOOP_NONBLOCK)</code>, but in the most	1815	similarly to <code>ev_loop (embedded_loop, EVLOOP_NONBLOCK)</code>, but in the most
1243	apropriate way for embedded loops.</p>	1816	apropriate way for embedded loops.</p>
1244	</dd>	1817	</dd>
		1818	<dt>struct ev_loop *loop [read-only]</dt>
		1819	<dd>
		1820	<p>The embedded event loop.</p>
		1821	</dd>
1245	</dl>	1822	</dl>
1246		1823
1247		1824
1248		1825
1249		1826
1250		1827
1251	</div>	1828	</div>
1252	<h1 id="OTHER_FUNCTIONS">OTHER FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p>	1829	<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>
		1830	<div id="code_ev_fork_code_the_audacity_to_re-2">
		1831	<p>Fork watchers are called when a <code>fork ()</code> was detected (usually because
		1832	whoever is a good citizen cared to tell libev about it by calling
		1833	<code>ev_default_fork</code> or <code>ev_loop_fork</code>). The invocation is done before the
		1834	event loop blocks next and before <code>ev_check</code> watchers are being called,
		1835	and only in the child after the fork. If whoever good citizen calling
		1836	<code>ev_default_fork</code> cheats and calls it in the wrong process, the fork
		1837	handlers will be invoked, too, of course.</p>
		1838
		1839	</div>
		1840	<h3 id="Watcher_Specific_Functions_and_Data_-10">Watcher-Specific Functions and Data Members</h3>
		1841	<div id="Watcher_Specific_Functions_and_Data_-2-8">
		1842	<dl>
		1843	<dt>ev_fork_init (ev_signal *, callback)</dt>
		1844	<dd>
		1845	<p>Initialises and configures the fork watcher - it has no parameters of any
		1846	kind. There is a <code>ev_fork_set</code> macro, but using it is utterly pointless,
		1847	believe me.</p>
		1848	</dd>
		1849	</dl>
		1850
		1851
		1852
		1853
		1854
		1855	</div>
		1856	<h1 id="OTHER_FUNCTIONS">OTHER FUNCTIONS</h1>
1253	<div id="OTHER_FUNCTIONS_CONTENT">	1857	<div id="OTHER_FUNCTIONS_CONTENT">
1254	<p>There are some other functions of possible interest. Described. Here. Now.</p>	1858	<p>There are some other functions of possible interest. Described. Here. Now.</p>
1255	<dl>	1859	<dl>
1256	<dt>ev_once (loop, int fd, int events, ev_tstamp timeout, callback)</dt>	1860	<dt>ev_once (loop, int fd, int events, ev_tstamp timeout, callback)</dt>
1257	<dd>	1861	<dd>
…		…
1304		1908
1305		1909
1306		1910
1307		1911
1308	</div>	1912	</div>
1309	<h1 id="LIBEVENT_EMULATION">LIBEVENT EMULATION</h1><p><a href="#TOP" class="toplink">Top</a></p>	1913	<h1 id="LIBEVENT_EMULATION">LIBEVENT EMULATION</h1>
1310	<div id="LIBEVENT_EMULATION_CONTENT">	1914	<div id="LIBEVENT_EMULATION_CONTENT">
1311	<p>Libev offers a compatibility emulation layer for libevent. It cannot	1915	<p>Libev offers a compatibility emulation layer for libevent. It cannot
1312	emulate the internals of libevent, so here are some usage hints:</p>	1916	emulate the internals of libevent, so here are some usage hints:</p>
1313	<dl>	1917	<dl>
1314	<dt>* Use it by including <event.h>, as usual.</dt>	1918	<dt>* Use it by including <event.h>, as usual.</dt>
…		…
1324	<dt>* The libev emulation is <i>not</i> ABI compatible to libevent, you need	1928	<dt>* The libev emulation is <i>not</i> ABI compatible to libevent, you need
1325	to use the libev header file and library.</dt>	1929	to use the libev header file and library.</dt>
1326	</dl>	1930	</dl>
1327		1931
1328	</div>	1932	</div>
1329	<h1 id="C_SUPPORT">C++ SUPPORT</h1><p><a href="#TOP" class="toplink">Top</a></p>	1933	<h1 id="C_SUPPORT">C++ SUPPORT</h1>
1330	<div id="C_SUPPORT_CONTENT">	1934	<div id="C_SUPPORT_CONTENT">
1331	<p>Libev comes with some simplistic wrapper classes for C++ that mainly allow	1935	<p>Libev comes with some simplistic wrapper classes for C++ that mainly allow
1332	you to use some convinience methods to start/stop watchers and also change	1936	you to use some convinience methods to start/stop watchers and also change
1333	the callback model to a model using method callbacks on objects.</p>	1937	the callback model to a model using method callbacks on objects.</p>
1334	<p>To use it,</p>	1938	<p>To use it,</p>
1335	<pre> #include <ev++.h>	1939	<pre> #include <ev++.h>
1336		1940
1337	</pre>	1941	</pre>
1338	<p>(it is not installed by default). This automatically includes <cite>ev.h</cite>	1942	<p>This automatically includes <cite>ev.h</cite> and puts all of its definitions (many
1339	and puts all of its definitions (many of them macros) into the global	1943	of them macros) into the global namespace. All C++ specific things are
1340	namespace. All C++ specific things are put into the <code>ev</code> namespace.</p>	1944	put into the <code>ev</code> namespace. It should support all the same embedding
1341	<p>It should support all the same embedding options as <cite>ev.h</cite>, most notably	1945	options as <cite>ev.h</cite>, most notably <code>EV_MULTIPLICITY</code>.</p>
1342	<code>EV_MULTIPLICITY</code>.</p>	1946	<p>Care has been taken to keep the overhead low. The only data member the C++
		1947	classes add (compared to plain C-style watchers) is the event loop pointer
		1948	that the watcher is associated with (or no additional members at all if
		1949	you disable <code>EV_MULTIPLICITY</code> when embedding libev).</p>
		1950	<p>Currently, functions, and static and non-static member functions can be
		1951	used as callbacks. Other types should be easy to add as long as they only
		1952	need one additional pointer for context. If you need support for other
		1953	types of functors please contact the author (preferably after implementing
		1954	it).</p>
1343	<p>Here is a list of things available in the <code>ev</code> namespace:</p>	1955	<p>Here is a list of things available in the <code>ev</code> namespace:</p>
1344	<dl>	1956	<dl>
1345	<dt><code>ev::READ</code>, <code>ev::WRITE</code> etc.</dt>	1957	<dt><code>ev::READ</code>, <code>ev::WRITE</code> etc.</dt>
1346	<dd>	1958	<dd>
1347	<p>These are just enum values with the same values as the <code>EV_READ</code> etc.	1959	<p>These are just enum values with the same values as the <code>EV_READ</code> etc.
…		…
1358	which is called <code>ev::sig</code> to avoid clashes with the <code>signal</code> macro	1970	which is called <code>ev::sig</code> to avoid clashes with the <code>signal</code> macro
1359	defines by many implementations.</p>	1971	defines by many implementations.</p>
1360	<p>All of those classes have these methods:</p>	1972	<p>All of those classes have these methods:</p>
1361	<p>	1973	<p>
1362	<dl>	1974	<dl>
1363	<dt>ev::TYPE::TYPE (object , object::method )</dt>	1975	<dt>ev::TYPE::TYPE ()</dt>
1364	<dt>ev::TYPE::TYPE (object , object::method , struct ev_loop *)</dt>	1976	<dt>ev::TYPE::TYPE (struct ev_loop *)</dt>
1365	<dt>ev::TYPE::~TYPE</dt>	1977	<dt>ev::TYPE::~TYPE</dt>
1366	<dd>	1978	<dd>
1367	<p>The constructor takes a pointer to an object and a method pointer to	1979	<p>The constructor (optionally) takes an event loop to associate the watcher
1368	the event handler callback to call in this class. The constructor calls	1980	with. If it is omitted, it will use <code>EV_DEFAULT</code>.</p>
1369	<code>ev_init</code> for you, which means you have to call the <code>set</code> method	1981	<p>The constructor calls <code>ev_init</code> for you, which means you have to call the
1370	before starting it. If you do not specify a loop then the constructor	1982	<code>set</code> method before starting it.</p>
1371	automatically associates the default loop with this watcher.</p>	1983	<p>It will not set a callback, however: You have to call the templated <code>set</code>
		1984	method to set a callback before you can start the watcher.</p>
		1985	<p>(The reason why you have to use a method is a limitation in C++ which does
		1986	not allow explicit template arguments for constructors).</p>
1372	<p>The destructor automatically stops the watcher if it is active.</p>	1987	<p>The destructor automatically stops the watcher if it is active.</p>
		1988	</dd>
		1989	<dt>w->set<class, &class::method> (object *)</dt>
		1990	<dd>
		1991	<p>This method sets the callback method to call. The method has to have a
		1992	signature of <code>void (*)(ev_TYPE &, int)</code>, it receives the watcher as
		1993	first argument and the <code>revents</code> as second. The object must be given as
		1994	parameter and is stored in the <code>data</code> member of the watcher.</p>
		1995	<p>This method synthesizes efficient thunking code to call your method from
		1996	the C callback that libev requires. If your compiler can inline your
		1997	callback (i.e. it is visible to it at the place of the <code>set</code> call and
		1998	your compiler is good :), then the method will be fully inlined into the
		1999	thunking function, making it as fast as a direct C callback.</p>
		2000	<p>Example: simple class declaration and watcher initialisation</p>
		2001	<pre> struct myclass
		2002	{
		2003	void io_cb (ev::io &w, int revents) { }
		2004	}
		2005
		2006	myclass obj;
		2007	ev::io iow;
		2008	iow.set <myclass, &myclass::io_cb> (&obj);
		2009
		2010	</pre>
		2011	</dd>
		2012	<dt>w->set<function> (void *data = 0)</dt>
		2013	<dd>
		2014	<p>Also sets a callback, but uses a static method or plain function as
		2015	callback. The optional <code>data</code> argument will be stored in the watcher's
		2016	<code>data</code> member and is free for you to use.</p>
		2017	<p>The prototype of the <code>function</code> must be <code>void (*)(ev::TYPE &w, int)</code>.</p>
		2018	<p>See the method-<code>set</code> above for more details.</p>
		2019	<p>Example:</p>
		2020	<pre> static void io_cb (ev::io &w, int revents) { }
		2021	iow.set <io_cb> ();
		2022
		2023	</pre>
1373	</dd>	2024	</dd>
1374	<dt>w->set (struct ev_loop *)</dt>	2025	<dt>w->set (struct ev_loop *)</dt>
1375	<dd>	2026	<dd>
1376	<p>Associates a different <code>struct ev_loop</code> with this watcher. You can only	2027	<p>Associates a different <code>struct ev_loop</code> with this watcher. You can only
1377	do this when the watcher is inactive (and not pending either).</p>	2028	do this when the watcher is inactive (and not pending either).</p>
1378	</dd>	2029	</dd>
1379	<dt>w->set ([args])</dt>	2030	<dt>w->set ([args])</dt>
1380	<dd>	2031	<dd>
1381	<p>Basically the same as <code>ev_TYPE_set</code>, with the same args. Must be	2032	<p>Basically the same as <code>ev_TYPE_set</code>, with the same args. Must be
1382	called at least once. Unlike the C counterpart, an active watcher gets	2033	called at least once. Unlike the C counterpart, an active watcher gets
1383	automatically stopped and restarted.</p>	2034	automatically stopped and restarted when reconfiguring it with this
		2035	method.</p>
1384	</dd>	2036	</dd>
1385	<dt>w->start ()</dt>	2037	<dt>w->start ()</dt>
1386	<dd>	2038	<dd>
1387	<p>Starts the watcher. Note that there is no <code>loop</code> argument as the	2039	<p>Starts the watcher. Note that there is no <code>loop</code> argument, as the
1388	constructor already takes the loop.</p>	2040	constructor already stores the event loop.</p>
1389	</dd>	2041	</dd>
1390	<dt>w->stop ()</dt>	2042	<dt>w->stop ()</dt>
1391	<dd>	2043	<dd>
1392	<p>Stops the watcher if it is active. Again, no <code>loop</code> argument.</p>	2044	<p>Stops the watcher if it is active. Again, no <code>loop</code> argument.</p>
1393	</dd>	2045	</dd>
…		…
1397	<code>ev_TYPE_again</code> function.</p>	2049	<code>ev_TYPE_again</code> function.</p>
1398	</dd>	2050	</dd>
1399	<dt>w->sweep () <code>ev::embed</code> only</dt>	2051	<dt>w->sweep () <code>ev::embed</code> only</dt>
1400	<dd>	2052	<dd>
1401	<p>Invokes <code>ev_embed_sweep</code>.</p>	2053	<p>Invokes <code>ev_embed_sweep</code>.</p>
		2054	</dd>
		2055	<dt>w->update () <code>ev::stat</code> only</dt>
		2056	<dd>
		2057	<p>Invokes <code>ev_stat_stat</code>.</p>
1402	</dd>	2058	</dd>
1403	</dl>	2059	</dl>
1404	</p>	2060	</p>
1405	</dd>	2061	</dd>
1406	</dl>	2062	</dl>
…		…
1413		2069
1414	myclass ();	2070	myclass ();
1415	}	2071	}
1416		2072
1417	myclass::myclass (int fd)	2073	myclass::myclass (int fd)
1418	: io (this, &myclass::io_cb),
1419	idle (this, &myclass::idle_cb)
1420	{	2074	{
		2075	io .set <myclass, &myclass::io_cb > (this);
		2076	idle.set <myclass, &myclass::idle_cb> (this);
		2077
1421	io.start (fd, ev::READ);	2078	io.start (fd, ev::READ);
1422	}	2079	}
1423		2080
1424	</pre>
1425		2081
		2082
		2083
		2084	</pre>
		2085
1426	</div>	2086	</div>
1427	<h1 id="EMBEDDING">EMBEDDING</h1><p><a href="#TOP" class="toplink">Top</a></p>	2087	<h1 id="MACRO_MAGIC">MACRO MAGIC</h1>
		2088	<div id="MACRO_MAGIC_CONTENT">
		2089	<p>Libev can be compiled with a variety of options, the most fundemantal is
		2090	<code>EV_MULTIPLICITY</code>. This option determines whether (most) functions and
		2091	callbacks have an initial <code>struct ev_loop *</code> argument.</p>
		2092	<p>To make it easier to write programs that cope with either variant, the
		2093	following macros are defined:</p>
		2094	<dl>
		2095	<dt><code>EV_A</code>, <code>EV_A_</code></dt>
		2096	<dd>
		2097	<p>This provides the loop <i>argument</i> for functions, if one is required ("ev
		2098	loop argument"). The <code>EV_A</code> form is used when this is the sole argument,
		2099	<code>EV_A_</code> is used when other arguments are following. Example:</p>
		2100	<pre> ev_unref (EV_A);
		2101	ev_timer_add (EV_A_ watcher);
		2102	ev_loop (EV_A_ 0);
		2103
		2104	</pre>
		2105	<p>It assumes the variable <code>loop</code> of type <code>struct ev_loop *</code> is in scope,
		2106	which is often provided by the following macro.</p>
		2107	</dd>
		2108	<dt><code>EV_P</code>, <code>EV_P_</code></dt>
		2109	<dd>
		2110	<p>This provides the loop <i>parameter</i> for functions, if one is required ("ev
		2111	loop parameter"). The <code>EV_P</code> form is used when this is the sole parameter,
		2112	<code>EV_P_</code> is used when other parameters are following. Example:</p>
		2113	<pre> // this is how ev_unref is being declared
		2114	static void ev_unref (EV_P);
		2115
		2116	// this is how you can declare your typical callback
		2117	static void cb (EV_P_ ev_timer *w, int revents)
		2118
		2119	</pre>
		2120	<p>It declares a parameter <code>loop</code> of type <code>struct ev_loop *</code>, quite
		2121	suitable for use with <code>EV_A</code>.</p>
		2122	</dd>
		2123	<dt><code>EV_DEFAULT</code>, <code>EV_DEFAULT_</code></dt>
		2124	<dd>
		2125	<p>Similar to the other two macros, this gives you the value of the default
		2126	loop, if multiple loops are supported ("ev loop default").</p>
		2127	</dd>
		2128	</dl>
		2129	<p>Example: Declare and initialise a check watcher, utilising the above
		2130	macros so it will work regardless of whether multiple loops are supported
		2131	or not.</p>
		2132	<pre> static void
		2133	check_cb (EV_P_ ev_timer *w, int revents)
		2134	{
		2135	ev_check_stop (EV_A_ w);
		2136	}
		2137
		2138	ev_check check;
		2139	ev_check_init (&check, check_cb);
		2140	ev_check_start (EV_DEFAULT_ &check);
		2141	ev_loop (EV_DEFAULT_ 0);
		2142
		2143	</pre>
		2144
		2145	</div>
		2146	<h1 id="EMBEDDING">EMBEDDING</h1>
1428	<div id="EMBEDDING_CONTENT">	2147	<div id="EMBEDDING_CONTENT">
1429	<p>Libev can (and often is) directly embedded into host	2148	<p>Libev can (and often is) directly embedded into host
1430	applications. Examples of applications that embed it include the Deliantra	2149	applications. Examples of applications that embed it include the Deliantra
1431	Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe)	2150	Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe)
1432	and rxvt-unicode.</p>	2151	and rxvt-unicode.</p>
…		…
1469	ev_vars.h	2188	ev_vars.h
1470	ev_wrap.h	2189	ev_wrap.h
1471		2190
1472	ev_win32.c required on win32 platforms only	2191	ev_win32.c required on win32 platforms only
1473		2192
1474	ev_select.c only when select backend is enabled (which is by default)	2193	ev_select.c only when select backend is enabled (which is enabled by default)
1475	ev_poll.c only when poll backend is enabled (disabled by default)	2194	ev_poll.c only when poll backend is enabled (disabled by default)
1476	ev_epoll.c only when the epoll backend is enabled (disabled by default)	2195	ev_epoll.c only when the epoll backend is enabled (disabled by default)
1477	ev_kqueue.c only when the kqueue backend is enabled (disabled by default)	2196	ev_kqueue.c only when the kqueue backend is enabled (disabled by default)
1478	ev_port.c only when the solaris port backend is enabled (disabled by default)	2197	ev_port.c only when the solaris port backend is enabled (disabled by default)
1479		2198
…		…
1606	</dd>	2325	</dd>
1607	<dt>EV_USE_DEVPOLL</dt>	2326	<dt>EV_USE_DEVPOLL</dt>
1608	<dd>	2327	<dd>
1609	<p>reserved for future expansion, works like the USE symbols above.</p>	2328	<p>reserved for future expansion, works like the USE symbols above.</p>
1610	</dd>	2329	</dd>
		2330	<dt>EV_USE_INOTIFY</dt>
		2331	<dd>
		2332	<p>If defined to be <code>1</code>, libev will compile in support for the Linux inotify
		2333	interface to speed up <code>ev_stat</code> watchers. Its actual availability will
		2334	be detected at runtime.</p>
		2335	</dd>
1611	<dt>EV_H</dt>	2336	<dt>EV_H</dt>
1612	<dd>	2337	<dd>
1613	<p>The name of the <cite>ev.h</cite> header file used to include it. The default if	2338	<p>The name of the <cite>ev.h</cite> header file used to include it. The default if
1614	undefined is <code><ev.h></code> in <cite>event.h</cite> and <code>"ev.h"</code> in <cite>ev.c</cite>. This	2339	undefined is <code><ev.h></code> in <cite>event.h</cite> and <code>"ev.h"</code> in <cite>ev.c</cite>. This
1615	can be used to virtually rename the <cite>ev.h</cite> header file in case of conflicts.</p>	2340	can be used to virtually rename the <cite>ev.h</cite> header file in case of conflicts.</p>
…		…
1638	will have the <code>struct ev_loop *</code> as first argument, and you can create	2363	will have the <code>struct ev_loop *</code> as first argument, and you can create
1639	additional independent event loops. Otherwise there will be no support	2364	additional independent event loops. Otherwise there will be no support
1640	for multiple event loops and there is no first event loop pointer	2365	for multiple event loops and there is no first event loop pointer
1641	argument. Instead, all functions act on the single default loop.</p>	2366	argument. Instead, all functions act on the single default loop.</p>
1642	</dd>	2367	</dd>
1643	<dt>EV_PERIODICS</dt>	2368	<dt>EV_MINPRI</dt>
		2369	<dt>EV_MAXPRI</dt>
		2370	<dd>
		2371	<p>The range of allowed priorities. <code>EV_MINPRI</code> must be smaller or equal to
		2372	<code>EV_MAXPRI</code>, but otherwise there are no non-obvious limitations. You can
		2373	provide for more priorities by overriding those symbols (usually defined
		2374	to be <code>-2</code> and <code>2</code>, respectively).</p>
		2375	<p>When doing priority-based operations, libev usually has to linearly search
		2376	all the priorities, so having many of them (hundreds) uses a lot of space
		2377	and time, so using the defaults of five priorities (-2 .. +2) is usually
		2378	fine.</p>
		2379	<p>If your embedding app does not need any priorities, defining these both to
		2380	<code>0</code> will save some memory and cpu.</p>
1644	<dd>	2381	</dd>
		2382	<dt>EV_PERIODIC_ENABLE</dt>
		2383	<dd>
1645	<p>If undefined or defined to be <code>1</code>, then periodic timers are supported,	2384	<p>If undefined or defined to be <code>1</code>, then periodic timers are supported. If
1646	otherwise not. This saves a few kb of code.</p>	2385	defined to be <code>0</code>, then they are not. Disabling them saves a few kB of
		2386	code.</p>
		2387	</dd>
		2388	<dt>EV_IDLE_ENABLE</dt>
		2389	<dd>
		2390	<p>If undefined or defined to be <code>1</code>, then idle watchers are supported. If
		2391	defined to be <code>0</code>, then they are not. Disabling them saves a few kB of
		2392	code.</p>
		2393	</dd>
		2394	<dt>EV_EMBED_ENABLE</dt>
		2395	<dd>
		2396	<p>If undefined or defined to be <code>1</code>, then embed watchers are supported. If
		2397	defined to be <code>0</code>, then they are not.</p>
		2398	</dd>
		2399	<dt>EV_STAT_ENABLE</dt>
		2400	<dd>
		2401	<p>If undefined or defined to be <code>1</code>, then stat watchers are supported. If
		2402	defined to be <code>0</code>, then they are not.</p>
		2403	</dd>
		2404	<dt>EV_FORK_ENABLE</dt>
		2405	<dd>
		2406	<p>If undefined or defined to be <code>1</code>, then fork watchers are supported. If
		2407	defined to be <code>0</code>, then they are not.</p>
		2408	</dd>
		2409	<dt>EV_MINIMAL</dt>
		2410	<dd>
		2411	<p>If you need to shave off some kilobytes of code at the expense of some
		2412	speed, define this symbol to <code>1</code>. Currently only used for gcc to override
		2413	some inlining decisions, saves roughly 30% codesize of amd64.</p>
		2414	</dd>
		2415	<dt>EV_PID_HASHSIZE</dt>
		2416	<dd>
		2417	<p><code>ev_child</code> watchers use a small hash table to distribute workload by
		2418	pid. The default size is <code>16</code> (or <code>1</code> with <code>EV_MINIMAL</code>), usually more
		2419	than enough. If you need to manage thousands of children you might want to
		2420	increase this value (<i>must</i> be a power of two).</p>
		2421	</dd>
		2422	<dt>EV_INOTIFY_HASHSIZE</dt>
		2423	<dd>
		2424	<p><code>ev_staz</code> watchers use a small hash table to distribute workload by
		2425	inotify watch id. The default size is <code>16</code> (or <code>1</code> with <code>EV_MINIMAL</code>),
		2426	usually more than enough. If you need to manage thousands of <code>ev_stat</code>
		2427	watchers you might want to increase this value (<i>must</i> be a power of
		2428	two).</p>
1647	</dd>	2429	</dd>
1648	<dt>EV_COMMON</dt>	2430	<dt>EV_COMMON</dt>
1649	<dd>	2431	<dd>
1650	<p>By default, all watchers have a <code>void *data</code> member. By redefining	2432	<p>By default, all watchers have a <code>void *data</code> member. By redefining
1651	this macro to a something else you can include more and other types of	2433	this macro to a something else you can include more and other types of
…		…
1678	the <cite>libev/</cite> subdirectory and includes them in the <cite>EV/EVAPI.h</cite> (public	2460	the <cite>libev/</cite> subdirectory and includes them in the <cite>EV/EVAPI.h</cite> (public
1679	interface) and <cite>EV.xs</cite> (implementation) files. Only the <cite>EV.xs</cite> file	2461	interface) and <cite>EV.xs</cite> (implementation) files. Only the <cite>EV.xs</cite> file
1680	will be compiled. It is pretty complex because it provides its own header	2462	will be compiled. It is pretty complex because it provides its own header
1681	file.</p>	2463	file.</p>
1682	<p>The usage in rxvt-unicode is simpler. It has a <cite>ev_cpp.h</cite> header file	2464	<p>The usage in rxvt-unicode is simpler. It has a <cite>ev_cpp.h</cite> header file
1683	that everybody includes and which overrides some autoconf choices:</p>	2465	that everybody includes and which overrides some configure choices:</p>
		2466	<pre> #define EV_MINIMAL 1
1684	<pre> #define EV_USE_POLL 0	2467	#define EV_USE_POLL 0
1685	#define EV_MULTIPLICITY 0	2468	#define EV_MULTIPLICITY 0
1686	#define EV_PERIODICS 0	2469	#define EV_PERIODIC_ENABLE 0
		2470	#define EV_STAT_ENABLE 0
		2471	#define EV_FORK_ENABLE 0
1687	#define EV_CONFIG_H <config.h>	2472	#define EV_CONFIG_H <config.h>
		2473	#define EV_MINPRI 0
		2474	#define EV_MAXPRI 0
1688		2475
1689	#include "ev++.h"	2476	#include "ev++.h"
1690		2477
1691	</pre>	2478	</pre>
1692	<p>And a <cite>ev_cpp.C</cite> implementation file that contains libev proper and is compiled:</p>	2479	<p>And a <cite>ev_cpp.C</cite> implementation file that contains libev proper and is compiled:</p>
1693	<pre> #include "ev_cpp.h"	2480	<pre> #include "ev_cpp.h"
1694	#include "ev.c"	2481	#include "ev.c"
1695		2482
1696	</pre>
1697		2483
		2484
		2485
		2486	</pre>
		2487
1698	</div>	2488	</div>
1699	<h1 id="AUTHOR">AUTHOR</h1><p><a href="#TOP" class="toplink">Top</a></p>	2489	<h1 id="COMPLEXITIES">COMPLEXITIES</h1>
		2490	<div id="COMPLEXITIES_CONTENT">
		2491	<p>In this section the complexities of (many of) the algorithms used inside
		2492	libev will be explained. For complexity discussions about backends see the
		2493	documentation for <code>ev_default_init</code>.</p>
		2494	<p>All of the following are about amortised time: If an array needs to be
		2495	extended, libev needs to realloc and move the whole array, but this
		2496	happens asymptotically never with higher number of elements, so O(1) might
		2497	mean it might do a lengthy realloc operation in rare cases, but on average
		2498	it is much faster and asymptotically approaches constant time.</p>
		2499	<p>
		2500	<dl>
		2501	<dt>Starting and stopping timer/periodic watchers: O(log skipped_other_timers)</dt>
		2502	<dd>
		2503	<p>This means that, when you have a watcher that triggers in one hour and
		2504	there are 100 watchers that would trigger before that then inserting will
		2505	have to skip those 100 watchers.</p>
		2506	</dd>
		2507	<dt>Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)</dt>
		2508	<dd>
		2509	<p>That means that for changing a timer costs less than removing/adding them
		2510	as only the relative motion in the event queue has to be paid for.</p>
		2511	</dd>
		2512	<dt>Starting io/check/prepare/idle/signal/child watchers: O(1)</dt>
		2513	<dd>
		2514	<p>These just add the watcher into an array or at the head of a list.
		2515	=item Stopping check/prepare/idle watchers: O(1)</p>
		2516	</dd>
		2517	<dt>Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))</dt>
		2518	<dd>
		2519	<p>These watchers are stored in lists then need to be walked to find the
		2520	correct watcher to remove. The lists are usually short (you don't usually
		2521	have many watchers waiting for the same fd or signal).</p>
		2522	</dd>
		2523	<dt>Finding the next timer per loop iteration: O(1)</dt>
		2524	<dt>Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)</dt>
		2525	<dd>
		2526	<p>A change means an I/O watcher gets started or stopped, which requires
		2527	libev to recalculate its status (and possibly tell the kernel).</p>
		2528	</dd>
		2529	<dt>Activating one watcher: O(1)</dt>
		2530	<dt>Priority handling: O(number_of_priorities)</dt>
		2531	<dd>
		2532	<p>Priorities are implemented by allocating some space for each
		2533	priority. When doing priority-based operations, libev usually has to
		2534	linearly search all the priorities.</p>
		2535	</dd>
		2536	</dl>
		2537	</p>
		2538
		2539
		2540
		2541
		2542
		2543	</div>
		2544	<h1 id="AUTHOR">AUTHOR</h1>
1700	<div id="AUTHOR_CONTENT">	2545	<div id="AUTHOR_CONTENT">
1701	<p>Marc Lehmann <libev@schmorp.de>.</p>	2546	<p>Marc Lehmann <libev@schmorp.de>.</p>
1702		2547
1703	</div>	2548	</div>
1704	</div></body>	2549	</div></body>

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Revision 1.79 by root, Wed Dec 12 17:55:30 2007 UTC