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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 08:13:46 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>
24	<li><a href="#FUNCTIONS_CONTROLLING_THE_EVENT_LOOP">FUNCTIONS CONTROLLING THE EVENT LOOP</a></li>	25	<li><a href="#FUNCTIONS_CONTROLLING_THE_EVENT_LOOP">FUNCTIONS CONTROLLING THE EVENT LOOP</a></li>
25	<li><a href="#ANATOMY_OF_A_WATCHER">ANATOMY OF A WATCHER</a>	26	<li><a href="#ANATOMY_OF_A_WATCHER">ANATOMY OF A WATCHER</a>
26	<ul><li><a href="#SUMMARY_OF_GENERIC_WATCHER_FUNCTIONS">SUMMARY OF 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 recurring 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_wait_for_pid_stat"><code>ev_child</code> - wait for pid 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>
		79	<li><a href="#EMBEDDING">EMBEDDING</a>
		80	<ul><li><a href="#FILESETS">FILESETS</a>
		81	<ul><li><a href="#CORE_EVENT_LOOP">CORE EVENT LOOP</a></li>
		82	<li><a href="#LIBEVENT_COMPATIBILITY_API">LIBEVENT COMPATIBILITY API</a></li>
		83	<li><a href="#AUTOCONF_SUPPORT">AUTOCONF SUPPORT</a></li>
		84	</ul>
		85	</li>
		86	<li><a href="#PREPROCESSOR_SYMBOLS_MACROS">PREPROCESSOR SYMBOLS/MACROS</a></li>
		87	<li><a href="#EXAMPLES">EXAMPLES</a></li>
		88	</ul>
		89	</li>
		90	<li><a href="#COMPLEXITIES">COMPLEXITIES</a></li>
44	<li><a href="#AUTHOR">AUTHOR</a>	91	<li><a href="#AUTHOR">AUTHOR</a>
45	</li>	92	</li>
46	</ul><hr />	93	</ul><hr />
47	<!-- INDEX END -->	94	<!-- INDEX END -->
48		95
49	<h1 id="NAME">NAME</h1><p><a href="#TOP" class="toplink">Top</a></p>	96	<h1 id="NAME">NAME</h1>
50	<div id="NAME_CONTENT">	97	<div id="NAME_CONTENT">
51	<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>
52		99
53	</div>	100	</div>
54	<h1 id="SYNOPSIS">SYNOPSIS</h1><p><a href="#TOP" class="toplink">Top</a></p>	101	<h1 id="SYNOPSIS">SYNOPSIS</h1>
55	<div id="SYNOPSIS_CONTENT">	102	<div id="SYNOPSIS_CONTENT">
56	<pre> #include <ev.h>	103	<pre> #include <ev.h>
57		104
58	</pre>	105	</pre>
59		106
60	</div>	107	</div>
61	<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>
62	<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>
63	<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
64	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
65	these event sources and provide your program with events.</p>	160	these event sources and provide your program with events.</p>
66	<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
67	(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
…		…
70	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
71	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
72	watcher.</p>	167	watcher.</p>
73		168
74	</div>	169	</div>
75	<h1 id="FEATURES">FEATURES</h1><p><a href="#TOP" class="toplink">Top</a></p>	170	<h1 id="FEATURES">FEATURES</h1>
76	<div id="FEATURES_CONTENT">	171	<div id="FEATURES_CONTENT">
77	<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
78	kqueue mechanisms for file descriptor events, relative timers, absolute	173	BSD-specific <code>kqueue</code> and the Solaris-specific event port mechanisms
79	timers with customised rescheduling, signal events, process status change	174	for file descriptor events (<code>ev_io</code>), the Linux <code>inotify</code> interface
80	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
81	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
82	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
83	it to libevent for example).</p>	184	for example).</p>
84		185
85	</div>	186	</div>
86	<h1 id="CONVENTIONS">CONVENTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p>	187	<h1 id="CONVENTIONS">CONVENTIONS</h1>
87	<div id="CONVENTIONS_CONTENT">	188	<div id="CONVENTIONS_CONTENT">
88	<p>Libev is very configurable. In this manual the default configuration	189	<p>Libev is very configurable. In this manual the default configuration will
89	will be described, which supports multiple event loops. For more info	190	be described, which supports multiple event loops. For more info about
90	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
91	<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
92	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>
93	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>
94	will not have this argument.</p>
95		195
96	</div>	196	</div>
97	<h1 id="TIME_REPRESENTATION">TIME REPRESENTATION</h1><p><a href="#TOP" class="toplink">Top</a></p>	197	<h1 id="TIME_REPRESENTATION">TIME REPRESENTATION</h1>
98	<div id="TIME_REPRESENTATION_CONTENT">	198	<div id="TIME_REPRESENTATION_CONTENT">
99	<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
100	(fractional) number of seconds since the (POSIX) epoch (somewhere near	200	(fractional) number of seconds since the (POSIX) epoch (somewhere near
101	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
102	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
103	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
104	it, you should treat it as such.</p>	204	it, you should treat it as such.</p>
105		205
106
107
108
109
110	</div>	206	</div>
111	<h1 id="GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p>	207	<h1 id="GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</h1>
112	<div id="GLOBAL_FUNCTIONS_CONTENT">	208	<div id="GLOBAL_FUNCTIONS_CONTENT">
113	<p>These functions can be called anytime, even before initialising the	209	<p>These functions can be called anytime, even before initialising the
114	library in any way.</p>	210	library in any way.</p>
115	<dl>	211	<dl>
116	<dt>ev_tstamp ev_time ()</dt>	212	<dt>ev_tstamp ev_time ()</dt>
…		…
120	you actually want to know.</p>	216	you actually want to know.</p>
121	</dd>	217	</dd>
122	<dt>int ev_version_major ()</dt>	218	<dt>int ev_version_major ()</dt>
123	<dt>int ev_version_minor ()</dt>	219	<dt>int ev_version_minor ()</dt>
124	<dd>	220	<dd>
125	<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
126	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
127	<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
128	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
129	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>
130	<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,
131	as this indicates an incompatible change. Minor versions are usually	229	as this indicates an incompatible change. Minor versions are usually
132	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
133	not a problem.</p>	231	not a problem.</p>
134	<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
135	version:</p>	233	version.</p>
136	<pre> assert (("libev version mismatch",	234	<pre> assert (("libev version mismatch",
137	ev_version_major () == EV_VERSION_MAJOR	235	ev_version_major () == EV_VERSION_MAJOR
138	&& ev_version_minor () >= EV_VERSION_MINOR));	236	&& ev_version_minor () >= EV_VERSION_MINOR));
139		237
140	</pre>	238	</pre>
…		…
170	recommended ones.</p>	268	recommended ones.</p>
171	<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>
172	</dd>	270	</dd>
173	<dt>ev_set_allocator (void (cb)(void *ptr, long size))</dt>	271	<dt>ev_set_allocator (void (cb)(void *ptr, long size))</dt>
174	<dd>	272	<dd>
175	<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
176	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
177	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
178	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
179	destructive action. The default is your system realloc function.</p>	277	potentially destructive action. The default is your system realloc
		278	function.</p>
180	<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,
181	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,
182	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>
183	<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
184	retries: better than mine).</p>	283	retries).</p>
185	<pre> static void *	284	<pre> static void *
186	persistent_realloc (void *ptr, long size)	285	persistent_realloc (void *ptr, size_t size)
187	{	286	{
188	for (;;)	287	for (;;)
189	{	288	{
190	void *newptr = realloc (ptr, size);	289	void *newptr = realloc (ptr, size);
191		290
…		…
208	indicating the system call or subsystem causing the problem. If this	307	indicating the system call or subsystem causing the problem. If this
209	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
210	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
211	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
212	(such as abort).</p>	311	(such as abort).</p>
213	<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>
214	<pre> static void	313	<pre> static void
215	fatal_error (const char *msg)	314	fatal_error (const char *msg)
216	{	315	{
217	perror (msg);	316	perror (msg);
218	abort ();	317	abort ();
…		…
224	</pre>	323	</pre>
225	</dd>	324	</dd>
226	</dl>	325	</dl>
227		326
228	</div>	327	</div>
229	<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>
230	<div id="FUNCTIONS_CONTROLLING_THE_EVENT_LOOP-2">	329	<div id="FUNCTIONS_CONTROLLING_THE_EVENT_LOOP-2">
231	<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
232	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
233	events, and dynamically created loops which do not.</p>	332	events, and dynamically created loops which do not.</p>
234	<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
…		…
263	<code>LIBEV_FLAGS</code>. Otherwise (the default), this environment variable will	362	<code>LIBEV_FLAGS</code>. Otherwise (the default), this environment variable will
264	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
265	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
266	around bugs.</p>	365	around bugs.</p>
267	</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>
268	<dt><code>EVBACKEND_SELECT</code> (value 1, portable select backend)</dt>	384	<dt><code>EVBACKEND_SELECT</code> (value 1, portable select backend)</dt>
269	<dd>	385	<dd>
270	<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
271	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,
272	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
…		…
354	<dd>	470	<dd>
355	<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
356	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
357	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
358	undefined behaviour (or a failed assertion if assertions are enabled).</p>	474	undefined behaviour (or a failed assertion if assertions are enabled).</p>
359	<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>
360	<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);
361	if (!epoller)	477	if (!epoller)
362	fatal ("no epoll found here, maybe it hides under your chair");	478	fatal ("no epoll found here, maybe it hides under your chair");
363		479
364	</pre>	480	</pre>
365	</dd>	481	</dd>
366	<dt>ev_default_destroy ()</dt>	482	<dt>ev_default_destroy ()</dt>
367	<dd>	483	<dd>
368	<p>Destroys the default loop again (frees all memory and kernel state	484	<p>Destroys the default loop again (frees all memory and kernel state
369	etc.). This stops all registered event watchers (by not touching them in	485	etc.). None of the active event watchers will be stopped in the normal
370	any way whatsoever, although you cannot rely on this :).</p>	486	sense, so e.g. <code>ev_is_active</code> might still return true. It is your
		487	responsibility to either stop all watchers cleanly yoursef <i>before</i>
		488	calling this function, or cope with the fact afterwards (which is usually
		489	the easiest thing, youc na just ignore the watchers and/or <code>free ()</code> them
		490	for example).</p>
371	</dd>	491	</dd>
372	<dt>ev_loop_destroy (loop)</dt>	492	<dt>ev_loop_destroy (loop)</dt>
373	<dd>	493	<dd>
374	<p>Like <code>ev_default_destroy</code>, but destroys an event loop created by an	494	<p>Like <code>ev_default_destroy</code>, but destroys an event loop created by an
375	earlier call to <code>ev_loop_new</code>.</p>	495	earlier call to <code>ev_loop_new</code>.</p>
…		…
396	<dt>ev_loop_fork (loop)</dt>	516	<dt>ev_loop_fork (loop)</dt>
397	<dd>	517	<dd>
398	<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
399	<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
400	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>
401	</dd>	530	</dd>
402	<dt>unsigned int ev_backend (loop)</dt>	531	<dt>unsigned int ev_backend (loop)</dt>
403	<dd>	532	<dd>
404	<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
405	use.</p>	534	use.</p>
…		…
433	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
434	external event in conjunction with something not expressible using other	563	external event in conjunction with something not expressible using other
435	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
436	usually a better approach for this kind of thing.</p>	565	usually a better approach for this kind of thing.</p>
437	<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.
438	<pre> * If there are no active watchers (reference count is zero), return.	568	* If there are no active watchers (reference count is zero), return.
439	- Queue prepare watchers and then call all outstanding watchers.	569	- Queue all prepare watchers and then call all outstanding watchers.
440	- If we have been forked, recreate the kernel state.	570	- If we have been forked, recreate the kernel state.
441	- Update the kernel state with all outstanding changes.	571	- Update the kernel state with all outstanding changes.
442	- Update the "event loop time".	572	- Update the "event loop time".
443	- Calculate for how long to block.	573	- Calculate for how long to block.
444	- Block the process, waiting for any events.	574	- Block the process, waiting for any events.
…		…
453	be handled here by queueing them when their watcher gets executed.	583	be handled here by queueing them when their watcher gets executed.
454	- 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
455	were used, return, otherwise continue with step *.	585	were used, return, otherwise continue with step *.
456		586
457	</pre>	587	</pre>
458	<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
459	anymore.</p>	589	anymore.</p>
460	<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
461	... 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..)
462	ev_loop (my_loop, 0);	592	ev_loop (my_loop, 0);
463	... jobs done. yeah!	593	... jobs done. yeah!
…		…
482	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
483	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
484	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
485	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
486	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>
487	<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>
488	running when nothing else is active.</p>	618	running when nothing else is active.</p>
489	<pre> struct dv_signal exitsig;	619	<pre> struct ev_signal exitsig;
490	ev_signal_init (&exitsig, sig_cb, SIGINT);	620	ev_signal_init (&exitsig, sig_cb, SIGINT);
491	ev_signal_start (myloop, &exitsig);	621	ev_signal_start (loop, &exitsig);
492	evf_unref (myloop);	622	evf_unref (loop);
493		623
494	</pre>	624	</pre>
495	<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>
496	<pre> ev_ref (myloop);	626	<pre> ev_ref (loop);
497	ev_signal_stop (myloop, &exitsig);	627	ev_signal_stop (loop, &exitsig);
498		628
499	</pre>	629	</pre>
500	</dd>	630	</dd>
501	</dl>	631	</dl>
502		632
		633
		634
		635
		636
503	</div>	637	</div>
504	<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>
505	<div id="ANATOMY_OF_A_WATCHER_CONTENT">	639	<div id="ANATOMY_OF_A_WATCHER_CONTENT">
506	<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
507	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
508	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>
509	<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)
…		…
566	</dd>	700	</dd>
567	<dt><code>EV_CHILD</code></dt>	701	<dt><code>EV_CHILD</code></dt>
568	<dd>	702	<dd>
569	<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>
570	</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>
571	<dt><code>EV_IDLE</code></dt>	709	<dt><code>EV_IDLE</code></dt>
572	<dd>	710	<dd>
573	<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>
574	</dd>	712	</dd>
575	<dt><code>EV_PREPARE</code></dt>	713	<dt><code>EV_PREPARE</code></dt>
…		…
580	<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
581	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
582	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
583	(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
584	<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>
585	</dd>	732	</dd>
586	<dt><code>EV_ERROR</code></dt>	733	<dt><code>EV_ERROR</code></dt>
587	<dd>	734	<dd>
588	<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
589	happen because the watcher could not be properly started because libev	736	happen because the watcher could not be properly started because libev
…		…
597	programs, though, so beware.</p>	744	programs, though, so beware.</p>
598	</dd>	745	</dd>
599	</dl>	746	</dl>
600		747
601	</div>	748	</div>
602	<h2 id="SUMMARY_OF_GENERIC_WATCHER_FUNCTIONS">SUMMARY OF GENERIC WATCHER FUNCTIONS</h2>	749	<h2 id="GENERIC_WATCHER_FUNCTIONS">GENERIC WATCHER FUNCTIONS</h2>
603	<div id="SUMMARY_OF_GENERIC_WATCHER_FUNCTIONS-2">	750	<div id="GENERIC_WATCHER_FUNCTIONS_CONTENT">
604	<p>In the following description, <code>TYPE</code> stands for the watcher type,	751	<p>In the following description, <code>TYPE</code> stands for the watcher type,
605	e.g. <code>timer</code> for <code>ev_timer</code> watchers and <code>io</code> for <code>ev_io</code> watchers.</p>	752	e.g. <code>timer</code> for <code>ev_timer</code> watchers and <code>io</code> for <code>ev_io</code> watchers.</p>
606	<dl>	753	<dl>
607	<dt><code>ev_init</code> (ev_TYPE *watcher, callback)</dt>	754	<dt><code>ev_init</code> (ev_TYPE *watcher, callback)</dt>
608	<dd>	755	<dd>
…		…
612	the type-specific <code>ev_TYPE_set</code> macro afterwards to initialise the	759	the type-specific <code>ev_TYPE_set</code> macro afterwards to initialise the
613	type-specific parts. For each type there is also a <code>ev_TYPE_init</code> macro	760	type-specific parts. For each type there is also a <code>ev_TYPE_init</code> macro
614	which rolls both calls into one.</p>	761	which rolls both calls into one.</p>
615	<p>You can reinitialise a watcher at any time as long as it has been stopped	762	<p>You can reinitialise a watcher at any time as long as it has been stopped
616	(or never started) and there are no pending events outstanding.</p>	763	(or never started) and there are no pending events outstanding.</p>
617	<p>The callbakc is always of type <code>void ()(ev_loop loop, ev_TYPE *watcher,	764	<p>The callback is always of type <code>void ()(ev_loop loop, ev_TYPE *watcher,
618	int revents)</code>.</p>	765	int revents)</code>.</p>
619	</dd>	766	</dd>
620	<dt><code>ev_TYPE_set</code> (ev_TYPE *, [args])</dt>	767	<dt><code>ev_TYPE_set</code> (ev_TYPE *, [args])</dt>
621	<dd>	768	<dd>
622	<p>This macro initialises the type-specific parts of a watcher. You need to	769	<p>This macro initialises the type-specific parts of a watcher. You need to
…		…
656	<dt>bool ev_is_pending (ev_TYPE *watcher)</dt>	803	<dt>bool ev_is_pending (ev_TYPE *watcher)</dt>
657	<dd>	804	<dd>
658	<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
659	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
660	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
661	<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
662	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>
663	</dd>	811	</dd>
664	<dt>callback = ev_cb (ev_TYPE *watcher)</dt>	812	<dt>callback ev_cb (ev_TYPE *watcher)</dt>
665	<dd>	813	<dd>
666	<p>Returns the callback currently set on the watcher.</p>	814	<p>Returns the callback currently set on the watcher.</p>
667	</dd>	815	</dd>
668	<dt>ev_cb_set (ev_TYPE *watcher, callback)</dt>	816	<dt>ev_cb_set (ev_TYPE *watcher, callback)</dt>
669	<dd>	817	<dd>
670	<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
671	(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>
672	</dd>	854	</dd>
673	</dl>	855	</dl>
674		856
675		857
676		858
…		…
701	struct my_io w = (struct my_io )w_;	883	struct my_io w = (struct my_io )w_;
702	...	884	...
703	}	885	}
704		886
705	</pre>	887	</pre>
706	<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
707	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	}
708		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>
709		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	}
710		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	}
711		917
712		918
		919
		920
		921	</pre>
		922
713	</div>	923	</div>
714	<h1 id="WATCHER_TYPES">WATCHER TYPES</h1><p><a href="#TOP" class="toplink">Top</a></p>	924	<h1 id="WATCHER_TYPES">WATCHER TYPES</h1>
715	<div id="WATCHER_TYPES_CONTENT">	925	<div id="WATCHER_TYPES_CONTENT">
716	<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
717	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>
718		937
719		938
720		939
721		940
722		941
723	</div>	942	</div>
724	<h2 id="code_ev_io_code_is_this_file_descrip"><code>ev_io</code> - is this file descriptor readable or writable</h2>	943	<h2 id="code_ev_io_code_is_this_file_descrip"><code>ev_io</code> - is this file descriptor readable or writable?</h2>
725	<div id="code_ev_io_code_is_this_file_descrip-2">	944	<div id="code_ev_io_code_is_this_file_descrip-2">
726	<p>I/O watchers check whether a file descriptor is readable or writable	945	<p>I/O watchers check whether a file descriptor is readable or writable
727	in each iteration of the event loop (This behaviour is called	946	in each iteration of the event loop, or, more precisely, when reading
728	level-triggering because you keep receiving events as long as the	947	would not block the process and writing would at least be able to write
729	condition persists. Remember you can stop the watcher if you don't want to	948	some data. This behaviour is called level-triggering because you keep
730	act on the event and neither want to receive future events).</p>	949	receiving events as long as the condition persists. Remember you can stop
		950	the watcher if you don't want to act on the event and neither want to
		951	receive future events.</p>
731	<p>In general you can register as many read and/or write event watchers per	952	<p>In general you can register as many read and/or write event watchers per
732	fd as you want (as long as you don't confuse yourself). Setting all file	953	fd as you want (as long as you don't confuse yourself). Setting all file
733	descriptors to non-blocking mode is also usually a good idea (but not	954	descriptors to non-blocking mode is also usually a good idea (but not
734	required if you know what you are doing).</p>	955	required if you know what you are doing).</p>
735	<p>You have to be careful with dup'ed file descriptors, though. Some backends	956	<p>You have to be careful with dup'ed file descriptors, though. Some backends
736	(the linux epoll backend is a notable example) cannot handle dup'ed file	957	(the linux epoll backend is a notable example) cannot handle dup'ed file
737	descriptors correctly if you register interest in two or more fds pointing	958	descriptors correctly if you register interest in two or more fds pointing
738	to the same underlying file/socket etc. description (that is, they share	959	to the same underlying file/socket/etc. description (that is, they share
739	the same underlying "file open").</p>	960	the same underlying "file open").</p>
740	<p>If you must do this, then force the use of a known-to-be-good backend	961	<p>If you must do this, then force the use of a known-to-be-good backend
741	(at the time of this writing, this includes only <code>EVBACKEND_SELECT</code> and	962	(at the time of this writing, this includes only <code>EVBACKEND_SELECT</code> and
742	<code>EVBACKEND_POLL</code>).</p>	963	<code>EVBACKEND_POLL</code>).</p>
		964	<p>Another thing you have to watch out for is that it is quite easy to
		965	receive "spurious" readyness notifications, that is your callback might
		966	be called with <code>EV_READ</code> but a subsequent <code>read</code>(2) will actually block
		967	because there is no data. Not only are some backends known to create a
		968	lot of those (for example solaris ports), it is very easy to get into
		969	this situation even with a relatively standard program structure. Thus
		970	it is best to always use non-blocking I/O: An extra <code>read</code>(2) returning
		971	<code>EAGAIN</code> is far preferable to a program hanging until some data arrives.</p>
		972	<p>If you cannot run the fd in non-blocking mode (for example you should not
		973	play around with an Xlib connection), then you have to seperately re-test
		974	whether a file descriptor is really ready with a known-to-be good interface
		975	such as poll (fortunately in our Xlib example, Xlib already does this on
		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">
743	<dl>	1005	<dl>
744	<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>
745	<dt>ev_io_set (ev_io *, int fd, int events)</dt>	1007	<dt>ev_io_set (ev_io *, int fd, int events)</dt>
746	<dd>	1008	<dd>
747	<p>Configures an <code>ev_io</code> watcher. The fd is the file descriptor to rceeive	1009	<p>Configures an <code>ev_io</code> watcher. The <code>fd</code> is the file descriptor to
748	events for and events is either <code>EV_READ</code>, <code>EV_WRITE</code> or <code>EV_READ \|	1010	rceeive events for and events is either <code>EV_READ</code>, <code>EV_WRITE</code> or
749	EV_WRITE</code> to receive the given events.</p>	1011	<code>EV_READ \| EV_WRITE</code> to receive the given events.</p>
750	<p>Please note that most of the more scalable backend mechanisms (for example	1012	</dd>
751	epoll and solaris ports) can result in spurious readyness notifications	1013	<dt>int fd [read-only]</dt>
752	for file descriptors, so you practically need to use non-blocking I/O (and	1014	<dd>
753	treat callback invocation as hint only), or retest separately with a safe	1015	<p>The file descriptor being watched.</p>
754	interface before doing I/O (XLib can do this), or force the use of either	1016	</dd>
755	<code>EVBACKEND_SELECT</code> or <code>EVBACKEND_POLL</code>, which don't suffer from this	1017	<dt>int events [read-only]</dt>
756	problem. Also note that it is quite easy to have your callback invoked	1018	<dd>
757	when the readyness condition is no longer valid even when employing	1019	<p>The events being watched.</p>
758	typical ways of handling events, so its a good idea to use non-blocking
759	I/O unconditionally.</p>
760	</dd>	1020	</dd>
761	</dl>	1021	</dl>
762	<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
763	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
764	attempt to read a whole line in the callback:</p>	1024	attempt to read a whole line in the callback.</p>
765	<pre> static void	1025	<pre> static void
766	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)
767	{	1027	{
768	ev_io_stop (loop, w);	1028	ev_io_stop (loop, w);
769	.. 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
…		…
780		1040
781		1041
782	</pre>	1042	</pre>
783		1043
784	</div>	1044	</div>
785	<h2 id="code_ev_timer_code_relative_and_opti"><code>ev_timer</code> - relative and optionally recurring timeouts</h2>	1045	<h2 id="code_ev_timer_code_relative_and_opti"><code>ev_timer</code> - relative and optionally repeating timeouts</h2>
786	<div id="code_ev_timer_code_relative_and_opti-2">	1046	<div id="code_ev_timer_code_relative_and_opti-2">
787	<p>Timer watchers are simple relative timers that generate an event after a	1047	<p>Timer watchers are simple relative timers that generate an event after a
788	given time, and optionally repeating in regular intervals after that.</p>	1048	given time, and optionally repeating in regular intervals after that.</p>
789	<p>The timers are based on real time, that is, if you register an event that	1049	<p>The timers are based on real time, that is, if you register an event that
790	times out after an hour and you reset your system clock to last years	1050	times out after an hour and you reset your system clock to last years
…		…
800		1060
801	</pre>	1061	</pre>
802	<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,
803	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
804	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">
805	<dl>	1069	<dl>
806	<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>
807	<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>
808	<dd>	1072	<dd>
809	<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
…		…
818	</dd>	1082	</dd>
819	<dt>ev_timer_again (loop)</dt>	1083	<dt>ev_timer_again (loop)</dt>
820	<dd>	1084	<dd>
821	<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
822	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>
823	<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>
824	<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
825	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>
826	<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
827	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
828	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
829	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
830	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
831	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
832	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
833	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>
834	</dd>	1120	</dd>
835	</dl>	1121	</dl>
836	<p>Example: create a timer that fires after 60 seconds.</p>	1122	<p>Example: Create a timer that fires after 60 seconds.</p>
837	<pre> static void	1123	<pre> static void
838	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)
839	{	1125	{
840	.. one minute over, w is actually stopped right here	1126	.. one minute over, w is actually stopped right here
841	}	1127	}
…		…
843	struct ev_timer mytimer;	1129	struct ev_timer mytimer;
844	ev_timer_init (&mytimer, one_minute_cb, 60., 0.);	1130	ev_timer_init (&mytimer, one_minute_cb, 60., 0.);
845	ev_timer_start (loop, &mytimer);	1131	ev_timer_start (loop, &mytimer);
846		1132
847	</pre>	1133	</pre>
848	<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
849	inactivity.</p>	1135	inactivity.</p>
850	<pre> static void	1136	<pre> static void
851	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)
852	{	1138	{
853	.. ten seconds without any activity	1139	.. ten seconds without any activity
…		…
866		1152
867		1153
868	</pre>	1154	</pre>
869		1155
870	</div>	1156	</div>
871	<h2 id="code_ev_periodic_code_to_cron_or_not"><code>ev_periodic</code> - to cron or not to cron</h2>	1157	<h2 id="code_ev_periodic_code_to_cron_or_not"><code>ev_periodic</code> - to cron or not to cron?</h2>
872	<div id="code_ev_periodic_code_to_cron_or_not-2">	1158	<div id="code_ev_periodic_code_to_cron_or_not-2">
873	<p>Periodic watchers are also timers of a kind, but they are very versatile	1159	<p>Periodic watchers are also timers of a kind, but they are very versatile
874	(and unfortunately a bit complex).</p>	1160	(and unfortunately a bit complex).</p>
875	<p>Unlike <code>ev_timer</code>'s, they are not based on real time (or relative time)	1161	<p>Unlike <code>ev_timer</code>'s, they are not based on real time (or relative time)
876	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
877	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
878	periodic watcher to trigger in 10 seconds (by specifiying e.g. c<ev_now ()	1164	periodic watcher to trigger in 10 seconds (by specifiying e.g. <code>ev_now ()
879	+ 10.>) 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
880	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
881	roughly 10 seconds later and of course not if you reset your system time	1167	roughly 10 seconds later).</p>
882	again).</p>
883	<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
884	triggering an event on eahc midnight, local time.</p>	1169	triggering an event on each midnight, local time or other, complicated,
		1170	rules.</p>
885	<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
886	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
887	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">
888	<dl>	1178	<dl>
889	<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>
890	<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>
891	<dd>	1181	<dd>
892	<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
893	operation, and we will explain them from simplest to complex:</p>	1183	operation, and we will explain them from simplest to complex:</p>
894	<p>	1184	<p>
895	<dl>	1185	<dl>
896	<dt>* absolute timer (interval = reschedule_cb = 0)</dt>	1186	<dt>* absolute timer (at = time, interval = reschedule_cb = 0)</dt>
897	<dd>	1187	<dd>
898	<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
899	<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,
900	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
901	system time reaches or surpasses this time.</p>	1191	system time reaches or surpasses this time.</p>
902	</dd>	1192	</dd>
903	<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>
904	<dd>	1194	<dd>
905	<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
906	<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)
907	of any time jumps.</p>	1197	and then repeat, regardless of any time jumps.</p>
908	<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
909	time:</p>	1199	time:</p>
910	<pre> ev_periodic_set (&periodic, 0., 3600., 0);	1200	<pre> ev_periodic_set (&periodic, 0., 3600., 0);
911		1201
912	</pre>	1202	</pre>
…		…
915	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
916	by 3600.</p>	1206	by 3600.</p>
917	<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
918	<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
919	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>
920	</dd>	1213	</dd>
921	<dt>* manual reschedule mode (reschedule_cb = callback)</dt>	1214	<dt>* manual reschedule mode (at and interval ignored, reschedule_cb = callback)</dt>
922	<dd>	1215	<dd>
923	<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
924	ignored. Instead, each time the periodic watcher gets scheduled, the	1217	ignored. Instead, each time the periodic watcher gets scheduled, the
925	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
926	current time as second argument.</p>	1219	current time as second argument.</p>
927	<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,
928	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,
929	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
930	starting a prepare watcher).</p>	1223	starting an <code>ev_prepare</code> watcher, which is legal).</p>
931	<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,
932	ev_tstamp now)</code>, e.g.:</p>	1225	ev_tstamp now)</code>, e.g.:</p>
933	<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)
934	{	1227	{
935	return now + 60.;	1228	return now + 60.;
…		…
956	<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
957	when you changed some parameters or the reschedule callback would return	1250	when you changed some parameters or the reschedule callback would return
958	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
959	program when the crontabs have changed).</p>	1252	program when the crontabs have changed).</p>
960	</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>
961	</dl>	1273	</dl>
962	<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
963	system clock is divisible by 3600. The callback invocation times have	1275	system clock is divisible by 3600. The callback invocation times have
964	potentially a lot of jittering, but good long-term stability.</p>	1276	potentially a lot of jittering, but good long-term stability.</p>
965	<pre> static void	1277	<pre> static void
966	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)
967	{	1279	{
…		…
971	struct ev_periodic hourly_tick;	1283	struct ev_periodic hourly_tick;
972	ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);	1284	ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);
973	ev_periodic_start (loop, &hourly_tick);	1285	ev_periodic_start (loop, &hourly_tick);
974		1286
975	</pre>	1287	</pre>
976	<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>
977	<pre> #include <math.h>	1289	<pre> #include <math.h>
978		1290
979	static ev_tstamp	1291	static ev_tstamp
980	my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)	1292	my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)
981	{	1293	{
…		…
983	}	1295	}
984		1296
985	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);
986		1298
987	</pre>	1299	</pre>
988	<p>Example: call a callback every hour, starting now:</p>	1300	<p>Example: Call a callback every hour, starting now:</p>
989	<pre> struct ev_periodic hourly_tick;	1301	<pre> struct ev_periodic hourly_tick;
990	ev_periodic_init (&hourly_tick, clock_cb,	1302	ev_periodic_init (&hourly_tick, clock_cb,
991	fmod (ev_now (loop), 3600.), 3600., 0);	1303	fmod (ev_now (loop), 3600.), 3600., 0);
992	ev_periodic_start (loop, &hourly_tick);	1304	ev_periodic_start (loop, &hourly_tick);
993		1305
…		…
995		1307
996		1308
997	</pre>	1309	</pre>
998		1310
999	</div>	1311	</div>
1000	<h2 id="code_ev_signal_code_signal_me_when_a"><code>ev_signal</code> - signal me when a signal gets signalled</h2>	1312	<h2 id="code_ev_signal_code_signal_me_when_a"><code>ev_signal</code> - signal me when a signal gets signalled!</h2>
1001	<div id="code_ev_signal_code_signal_me_when_a-2">	1313	<div id="code_ev_signal_code_signal_me_when_a-2">
1002	<p>Signal watchers will trigger an event when the process receives a specific	1314	<p>Signal watchers will trigger an event when the process receives a specific
1003	signal one or more times. Even though signals are very asynchronous, libev	1315	signal one or more times. Even though signals are very asynchronous, libev
1004	will try it's best to deliver signals synchronously, i.e. as part of the	1316	will try it's best to deliver signals synchronously, i.e. as part of the
1005	normal event processing, like any other event.</p>	1317	normal event processing, like any other event.</p>
…		…
1007	first watcher gets started will libev actually register a signal watcher	1319	first watcher gets started will libev actually register a signal watcher
1008	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
1009	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
1010	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
1011	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">
1012	<dl>	1328	<dl>
1013	<dt>ev_signal_init (ev_signal *, callback, int signum)</dt>	1329	<dt>ev_signal_init (ev_signal *, callback, int signum)</dt>
1014	<dt>ev_signal_set (ev_signal *, int signum)</dt>	1330	<dt>ev_signal_set (ev_signal *, int signum)</dt>
1015	<dd>	1331	<dd>
1016	<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
1017	of the <code>SIGxxx</code> constants).</p>	1333	of the <code>SIGxxx</code> constants).</p>
1018	</dd>	1334	</dd>
		1335	<dt>int signum [read-only]</dt>
		1336	<dd>
		1337	<p>The signal the watcher watches out for.</p>
		1338	</dd>
1019	</dl>	1339	</dl>
1020		1340
1021		1341
1022		1342
1023		1343
1024		1344
1025	</div>	1345	</div>
1026	<h2 id="code_ev_child_code_wait_for_pid_stat"><code>ev_child</code> - wait for pid 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>
1027	<div id="code_ev_child_code_wait_for_pid_stat-2">	1347	<div id="code_ev_child_code_watch_out_for_pro-2">
1028	<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
1029	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">
1030	<dl>	1354	<dl>
1031	<dt>ev_child_init (ev_child *, callback, int pid)</dt>	1355	<dt>ev_child_init (ev_child *, callback, int pid)</dt>
1032	<dt>ev_child_set (ev_child *, int pid)</dt>	1356	<dt>ev_child_set (ev_child *, int pid)</dt>
1033	<dd>	1357	<dd>
1034	<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
…		…
1036	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
1037	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
1038	<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
1039	process causing the status change.</p>	1363	process causing the status change.</p>
1040	</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>
1041	</dl>	1378	</dl>
1042	<p>Example: try to exit cleanly on SIGINT and SIGTERM.</p>	1379	<p>Example: Try to exit cleanly on SIGINT and SIGTERM.</p>
1043	<pre> static void	1380	<pre> static void
1044	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)
1045	{	1382	{
1046	ev_unloop (loop, EVUNLOOP_ALL);	1383	ev_unloop (loop, EVUNLOOP_ALL);
1047	}	1384	}
…		…
1054		1391
1055		1392
1056	</pre>	1393	</pre>
1057		1394
1058	</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>
1059	<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>
1060	<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">
1061	<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
1062	(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
1063	as your process is busy handling sockets or timeouts (or even signals,	1504	count).</p>
1064	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
1065	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
1066	until stopped, that is, or your process receives more events and becomes	1509	iteration - until stopped, that is, or your process receives more events
1067	busy.</p>	1510	and becomes busy again with higher priority stuff.</p>
1068	<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
1069	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>
1070	<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
1071	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
1072	"pseudo-background processing", or delay processing stuff to after the	1515	"pseudo-background processing", or delay processing stuff to after the
1073	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">
1074	<dl>	1521	<dl>
1075	<dt>ev_idle_init (ev_signal *, callback)</dt>	1522	<dt>ev_idle_init (ev_signal *, callback)</dt>
1076	<dd>	1523	<dd>
1077	<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
1078	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,
1079	believe me.</p>	1526	believe me.</p>
1080	</dd>	1527	</dd>
1081	</dl>	1528	</dl>
1082	<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
1083	callback, free it. Alos, use no error checking, as usual.</p>	1530	callback, free it. Also, use no error checking, as usual.</p>
1084	<pre> static void	1531	<pre> static void
1085	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)
1086	{	1533	{
1087	free (w);	1534	free (w);
1088	// now do something you wanted to do when the program has	1535	// now do something you wanted to do when the program has
…		…
1097		1544
1098		1545
1099	</pre>	1546	</pre>
1100		1547
1101	</div>	1548	</div>
1102	<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>
1103	<div id="code_ev_prepare_code_and_code_ev_che-2">	1550	<div id="code_ev_prepare_code_and_code_ev_che-2">
1104	<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:
1105	prepare watchers get invoked before the process blocks and check watchers	1552	prepare watchers get invoked before the process blocks and check watchers
1106	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>
1107	<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
1108	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
1109	variable changes, implement your own watchers, integrate net-snmp or a	1563	variable changes, implement your own watchers, integrate net-snmp or a
1110	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>
1111	<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
1112	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
1113	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
1114	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
1115	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
…		…
1122	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
1123	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
1124	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
1125	loop from blocking if lower-priority coroutines are active, thus mapping	1582	loop from blocking if lower-priority coroutines are active, thus mapping
1126	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">
1127	<dl>	1597	<dl>
1128	<dt>ev_prepare_init (ev_prepare *, callback)</dt>	1598	<dt>ev_prepare_init (ev_prepare *, callback)</dt>
1129	<dt>ev_check_init (ev_check *, callback)</dt>	1599	<dt>ev_check_init (ev_check *, callback)</dt>
1130	<dd>	1600	<dd>
1131	<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
1132	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>
1133	macros, but using them is utterly, utterly and completely pointless.</p>	1603	macros, but using them is utterly, utterly and completely pointless.</p>
1134	</dd>	1604	</dd>
1135	</dl>	1605	</dl>
1136	<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;
1137		1619
		1620	static void
		1621	io_cb (ev_loop loop, ev_io w, int revents)
		1622	{
		1623	}
1138		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 ()));
1139		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);
1140		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)));
1141		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>
		1734
1142	</div>	1735	</div>
1143	<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>
1144	<div id="code_ev_embed_code_when_one_backend_-2">	1737	<div id="code_ev_embed_code_when_one_backend_-2">
1145	<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
1146	into another (currently only <code>ev_io</code> events are supported in the embedded	1739	into another (currently only <code>ev_io</code> events are supported in the embedded
1147	loop, other types of watchers might be handled in a delayed or incorrect	1740	loop, other types of watchers might be handled in a delayed or incorrect
1148	fashion and must not be used).</p>	1741	fashion and must not be used).</p>
…		…
1200	}	1793	}
1201	else	1794	else
1202	loop_lo = loop_hi;	1795	loop_lo = loop_hi;
1203		1796
1204	</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">
1205	<dl>	1802	<dl>
1206	<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>
1207	<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>
1208	<dd>	1805	<dd>
1209	<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
…		…
1216	<dd>	1813	<dd>
1217	<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
1218	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
1219	apropriate way for embedded loops.</p>	1816	apropriate way for embedded loops.</p>
1220	</dd>	1817	</dd>
		1818	<dt>struct ev_loop *loop [read-only]</dt>
		1819	<dd>
		1820	<p>The embedded event loop.</p>
		1821	</dd>
1221	</dl>	1822	</dl>
1222		1823
1223		1824
1224		1825
1225		1826
1226		1827
1227	</div>	1828	</div>
1228	<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>
1229	<div id="OTHER_FUNCTIONS_CONTENT">	1857	<div id="OTHER_FUNCTIONS_CONTENT">
1230	<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>
1231	<dl>	1859	<dl>
1232	<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>
1233	<dd>	1861	<dd>
…		…
1280		1908
1281		1909
1282		1910
1283		1911
1284	</div>	1912	</div>
1285	<h1 id="LIBEVENT_EMULATION">LIBEVENT EMULATION</h1><p><a href="#TOP" class="toplink">Top</a></p>	1913	<h1 id="LIBEVENT_EMULATION">LIBEVENT EMULATION</h1>
1286	<div id="LIBEVENT_EMULATION_CONTENT">	1914	<div id="LIBEVENT_EMULATION_CONTENT">
1287	<p>Libev offers a compatibility emulation layer for libevent. It cannot	1915	<p>Libev offers a compatibility emulation layer for libevent. It cannot
1288	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>
1289	<dl>	1917	<dl>
1290	<dt>* Use it by including <event.h>, as usual.</dt>	1918	<dt>* Use it by including <event.h>, as usual.</dt>
…		…
1300	<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
1301	to use the libev header file and library.</dt>	1929	to use the libev header file and library.</dt>
1302	</dl>	1930	</dl>
1303		1931
1304	</div>	1932	</div>
1305	<h1 id="C_SUPPORT">C++ SUPPORT</h1><p><a href="#TOP" class="toplink">Top</a></p>	1933	<h1 id="C_SUPPORT">C++ SUPPORT</h1>
1306	<div id="C_SUPPORT_CONTENT">	1934	<div id="C_SUPPORT_CONTENT">
1307	<p>TBD.</p>	1935	<p>Libev comes with some simplistic wrapper classes for C++ that mainly allow
		1936	you to use some convinience methods to start/stop watchers and also change
		1937	the callback model to a model using method callbacks on objects.</p>
		1938	<p>To use it,</p>
		1939	<pre> #include <ev++.h>
1308		1940
		1941	</pre>
		1942	<p>This automatically includes <cite>ev.h</cite> and puts all of its definitions (many
		1943	of them macros) into the global namespace. All C++ specific things are
		1944	put into the <code>ev</code> namespace. It should support all the same embedding
		1945	options as <cite>ev.h</cite>, most notably <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>
		1955	<p>Here is a list of things available in the <code>ev</code> namespace:</p>
		1956	<dl>
		1957	<dt><code>ev::READ</code>, <code>ev::WRITE</code> etc.</dt>
		1958	<dd>
		1959	<p>These are just enum values with the same values as the <code>EV_READ</code> etc.
		1960	macros from <cite>ev.h</cite>.</p>
		1961	</dd>
		1962	<dt><code>ev::tstamp</code>, <code>ev::now</code></dt>
		1963	<dd>
		1964	<p>Aliases to the same types/functions as with the <code>ev_</code> prefix.</p>
		1965	</dd>
		1966	<dt><code>ev::io</code>, <code>ev::timer</code>, <code>ev::periodic</code>, <code>ev::idle</code>, <code>ev::sig</code> etc.</dt>
		1967	<dd>
		1968	<p>For each <code>ev_TYPE</code> watcher in <cite>ev.h</cite> there is a corresponding class of
		1969	the same name in the <code>ev</code> namespace, with the exception of <code>ev_signal</code>
		1970	which is called <code>ev::sig</code> to avoid clashes with the <code>signal</code> macro
		1971	defines by many implementations.</p>
		1972	<p>All of those classes have these methods:</p>
		1973	<p>
		1974	<dl>
		1975	<dt>ev::TYPE::TYPE ()</dt>
		1976	<dt>ev::TYPE::TYPE (struct ev_loop *)</dt>
		1977	<dt>ev::TYPE::~TYPE</dt>
		1978	<dd>
		1979	<p>The constructor (optionally) takes an event loop to associate the watcher
		1980	with. If it is omitted, it will use <code>EV_DEFAULT</code>.</p>
		1981	<p>The constructor calls <code>ev_init</code> for you, which means you have to call the
		1982	<code>set</code> method before starting it.</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>
		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>
		2024	</dd>
		2025	<dt>w->set (struct ev_loop *)</dt>
		2026	<dd>
		2027	<p>Associates a different <code>struct ev_loop</code> with this watcher. You can only
		2028	do this when the watcher is inactive (and not pending either).</p>
		2029	</dd>
		2030	<dt>w->set ([args])</dt>
		2031	<dd>
		2032	<p>Basically the same as <code>ev_TYPE_set</code>, with the same args. Must be
		2033	called at least once. Unlike the C counterpart, an active watcher gets
		2034	automatically stopped and restarted when reconfiguring it with this
		2035	method.</p>
		2036	</dd>
		2037	<dt>w->start ()</dt>
		2038	<dd>
		2039	<p>Starts the watcher. Note that there is no <code>loop</code> argument, as the
		2040	constructor already stores the event loop.</p>
		2041	</dd>
		2042	<dt>w->stop ()</dt>
		2043	<dd>
		2044	<p>Stops the watcher if it is active. Again, no <code>loop</code> argument.</p>
		2045	</dd>
		2046	<dt>w->again () <code>ev::timer</code>, <code>ev::periodic</code> only</dt>
		2047	<dd>
		2048	<p>For <code>ev::timer</code> and <code>ev::periodic</code>, this invokes the corresponding
		2049	<code>ev_TYPE_again</code> function.</p>
		2050	</dd>
		2051	<dt>w->sweep () <code>ev::embed</code> only</dt>
		2052	<dd>
		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>
		2058	</dd>
		2059	</dl>
		2060	</p>
		2061	</dd>
		2062	</dl>
		2063	<p>Example: Define a class with an IO and idle watcher, start one of them in
		2064	the constructor.</p>
		2065	<pre> class myclass
		2066	{
		2067	ev_io io; void io_cb (ev::io &w, int revents);
		2068	ev_idle idle void idle_cb (ev::idle &w, int revents);
		2069
		2070	myclass ();
		2071	}
		2072
		2073	myclass::myclass (int fd)
		2074	{
		2075	io .set <myclass, &myclass::io_cb > (this);
		2076	idle.set <myclass, &myclass::idle_cb> (this);
		2077
		2078	io.start (fd, ev::READ);
		2079	}
		2080
		2081
		2082
		2083
		2084	</pre>
		2085
1309	</div>	2086	</div>
1310	<h1 id="AUTHOR">AUTHOR</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>
		2147	<div id="EMBEDDING_CONTENT">
		2148	<p>Libev can (and often is) directly embedded into host
		2149	applications. Examples of applications that embed it include the Deliantra
		2150	Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe)
		2151	and rxvt-unicode.</p>
		2152	<p>The goal is to enable you to just copy the neecssary files into your
		2153	source directory without having to change even a single line in them, so
		2154	you can easily upgrade by simply copying (or having a checked-out copy of
		2155	libev somewhere in your source tree).</p>
		2156
		2157	</div>
		2158	<h2 id="FILESETS">FILESETS</h2>
		2159	<div id="FILESETS_CONTENT">
		2160	<p>Depending on what features you need you need to include one or more sets of files
		2161	in your app.</p>
		2162
		2163	</div>
		2164	<h3 id="CORE_EVENT_LOOP">CORE EVENT LOOP</h3>
		2165	<div id="CORE_EVENT_LOOP_CONTENT">
		2166	<p>To include only the libev core (all the <code>ev_*</code> functions), with manual
		2167	configuration (no autoconf):</p>
		2168	<pre> #define EV_STANDALONE 1
		2169	#include "ev.c"
		2170
		2171	</pre>
		2172	<p>This will automatically include <cite>ev.h</cite>, too, and should be done in a
		2173	single C source file only to provide the function implementations. To use
		2174	it, do the same for <cite>ev.h</cite> in all files wishing to use this API (best
		2175	done by writing a wrapper around <cite>ev.h</cite> that you can include instead and
		2176	where you can put other configuration options):</p>
		2177	<pre> #define EV_STANDALONE 1
		2178	#include "ev.h"
		2179
		2180	</pre>
		2181	<p>Both header files and implementation files can be compiled with a C++
		2182	compiler (at least, thats a stated goal, and breakage will be treated
		2183	as a bug).</p>
		2184	<p>You need the following files in your source tree, or in a directory
		2185	in your include path (e.g. in libev/ when using -Ilibev):</p>
		2186	<pre> ev.h
		2187	ev.c
		2188	ev_vars.h
		2189	ev_wrap.h
		2190
		2191	ev_win32.c required on win32 platforms only
		2192
		2193	ev_select.c only when select backend is enabled (which is enabled by default)
		2194	ev_poll.c only when poll backend is enabled (disabled by default)
		2195	ev_epoll.c only when the epoll backend is enabled (disabled by default)
		2196	ev_kqueue.c only when the kqueue backend is enabled (disabled by default)
		2197	ev_port.c only when the solaris port backend is enabled (disabled by default)
		2198
		2199	</pre>
		2200	<p><cite>ev.c</cite> includes the backend files directly when enabled, so you only need
		2201	to compile this single file.</p>
		2202
		2203	</div>
		2204	<h3 id="LIBEVENT_COMPATIBILITY_API">LIBEVENT COMPATIBILITY API</h3>
		2205	<div id="LIBEVENT_COMPATIBILITY_API_CONTENT">
		2206	<p>To include the libevent compatibility API, also include:</p>
		2207	<pre> #include "event.c"
		2208
		2209	</pre>
		2210	<p>in the file including <cite>ev.c</cite>, and:</p>
		2211	<pre> #include "event.h"
		2212
		2213	</pre>
		2214	<p>in the files that want to use the libevent API. This also includes <cite>ev.h</cite>.</p>
		2215	<p>You need the following additional files for this:</p>
		2216	<pre> event.h
		2217	event.c
		2218
		2219	</pre>
		2220
		2221	</div>
		2222	<h3 id="AUTOCONF_SUPPORT">AUTOCONF SUPPORT</h3>
		2223	<div id="AUTOCONF_SUPPORT_CONTENT">
		2224	<p>Instead of using <code>EV_STANDALONE=1</code> and providing your config in
		2225	whatever way you want, you can also <code>m4_include([libev.m4])</code> in your
		2226	<cite>configure.ac</cite> and leave <code>EV_STANDALONE</code> undefined. <cite>ev.c</cite> will then
		2227	include <cite>config.h</cite> and configure itself accordingly.</p>
		2228	<p>For this of course you need the m4 file:</p>
		2229	<pre> libev.m4
		2230
		2231	</pre>
		2232
		2233	</div>
		2234	<h2 id="PREPROCESSOR_SYMBOLS_MACROS">PREPROCESSOR SYMBOLS/MACROS</h2>
		2235	<div id="PREPROCESSOR_SYMBOLS_MACROS_CONTENT">
		2236	<p>Libev can be configured via a variety of preprocessor symbols you have to define
		2237	before including any of its files. The default is not to build for multiplicity
		2238	and only include the select backend.</p>
		2239	<dl>
		2240	<dt>EV_STANDALONE</dt>
		2241	<dd>
		2242	<p>Must always be <code>1</code> if you do not use autoconf configuration, which
		2243	keeps libev from including <cite>config.h</cite>, and it also defines dummy
		2244	implementations for some libevent functions (such as logging, which is not
		2245	supported). It will also not define any of the structs usually found in
		2246	<cite>event.h</cite> that are not directly supported by the libev core alone.</p>
		2247	</dd>
		2248	<dt>EV_USE_MONOTONIC</dt>
		2249	<dd>
		2250	<p>If defined to be <code>1</code>, libev will try to detect the availability of the
		2251	monotonic clock option at both compiletime and runtime. Otherwise no use
		2252	of the monotonic clock option will be attempted. If you enable this, you
		2253	usually have to link against librt or something similar. Enabling it when
		2254	the functionality isn't available is safe, though, althoguh you have
		2255	to make sure you link against any libraries where the <code>clock_gettime</code>
		2256	function is hiding in (often <cite>-lrt</cite>).</p>
		2257	</dd>
		2258	<dt>EV_USE_REALTIME</dt>
		2259	<dd>
		2260	<p>If defined to be <code>1</code>, libev will try to detect the availability of the
		2261	realtime clock option at compiletime (and assume its availability at
		2262	runtime if successful). Otherwise no use of the realtime clock option will
		2263	be attempted. This effectively replaces <code>gettimeofday</code> by <code>clock_get
		2264	(CLOCK_REALTIME, ...)</code> and will not normally affect correctness. See tzhe note about libraries
		2265	in the description of <code>EV_USE_MONOTONIC</code>, though.</p>
		2266	</dd>
		2267	<dt>EV_USE_SELECT</dt>
		2268	<dd>
		2269	<p>If undefined or defined to be <code>1</code>, libev will compile in support for the
		2270	<code>select</code>(2) backend. No attempt at autodetection will be done: if no
		2271	other method takes over, select will be it. Otherwise the select backend
		2272	will not be compiled in.</p>
		2273	</dd>
		2274	<dt>EV_SELECT_USE_FD_SET</dt>
		2275	<dd>
		2276	<p>If defined to <code>1</code>, then the select backend will use the system <code>fd_set</code>
		2277	structure. This is useful if libev doesn't compile due to a missing
		2278	<code>NFDBITS</code> or <code>fd_mask</code> definition or it misguesses the bitset layout on
		2279	exotic systems. This usually limits the range of file descriptors to some
		2280	low limit such as 1024 or might have other limitations (winsocket only
		2281	allows 64 sockets). The <code>FD_SETSIZE</code> macro, set before compilation, might
		2282	influence the size of the <code>fd_set</code> used.</p>
		2283	</dd>
		2284	<dt>EV_SELECT_IS_WINSOCKET</dt>
		2285	<dd>
		2286	<p>When defined to <code>1</code>, the select backend will assume that
		2287	select/socket/connect etc. don't understand file descriptors but
		2288	wants osf handles on win32 (this is the case when the select to
		2289	be used is the winsock select). This means that it will call
		2290	<code>_get_osfhandle</code> on the fd to convert it to an OS handle. Otherwise,
		2291	it is assumed that all these functions actually work on fds, even
		2292	on win32. Should not be defined on non-win32 platforms.</p>
		2293	</dd>
		2294	<dt>EV_USE_POLL</dt>
		2295	<dd>
		2296	<p>If defined to be <code>1</code>, libev will compile in support for the <code>poll</code>(2)
		2297	backend. Otherwise it will be enabled on non-win32 platforms. It
		2298	takes precedence over select.</p>
		2299	</dd>
		2300	<dt>EV_USE_EPOLL</dt>
		2301	<dd>
		2302	<p>If defined to be <code>1</code>, libev will compile in support for the Linux
		2303	<code>epoll</code>(7) backend. Its availability will be detected at runtime,
		2304	otherwise another method will be used as fallback. This is the
		2305	preferred backend for GNU/Linux systems.</p>
		2306	</dd>
		2307	<dt>EV_USE_KQUEUE</dt>
		2308	<dd>
		2309	<p>If defined to be <code>1</code>, libev will compile in support for the BSD style
		2310	<code>kqueue</code>(2) backend. Its actual availability will be detected at runtime,
		2311	otherwise another method will be used as fallback. This is the preferred
		2312	backend for BSD and BSD-like systems, although on most BSDs kqueue only
		2313	supports some types of fds correctly (the only platform we found that
		2314	supports ptys for example was NetBSD), so kqueue might be compiled in, but
		2315	not be used unless explicitly requested. The best way to use it is to find
		2316	out whether kqueue supports your type of fd properly and use an embedded
		2317	kqueue loop.</p>
		2318	</dd>
		2319	<dt>EV_USE_PORT</dt>
		2320	<dd>
		2321	<p>If defined to be <code>1</code>, libev will compile in support for the Solaris
		2322	10 port style backend. Its availability will be detected at runtime,
		2323	otherwise another method will be used as fallback. This is the preferred
		2324	backend for Solaris 10 systems.</p>
		2325	</dd>
		2326	<dt>EV_USE_DEVPOLL</dt>
		2327	<dd>
		2328	<p>reserved for future expansion, works like the USE symbols above.</p>
		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>
		2336	<dt>EV_H</dt>
		2337	<dd>
		2338	<p>The name of the <cite>ev.h</cite> header file used to include it. The default if
		2339	undefined is <code><ev.h></code> in <cite>event.h</cite> and <code>"ev.h"</code> in <cite>ev.c</cite>. This
		2340	can be used to virtually rename the <cite>ev.h</cite> header file in case of conflicts.</p>
		2341	</dd>
		2342	<dt>EV_CONFIG_H</dt>
		2343	<dd>
		2344	<p>If <code>EV_STANDALONE</code> isn't <code>1</code>, this variable can be used to override
		2345	<cite>ev.c</cite>'s idea of where to find the <cite>config.h</cite> file, similarly to
		2346	<code>EV_H</code>, above.</p>
		2347	</dd>
		2348	<dt>EV_EVENT_H</dt>
		2349	<dd>
		2350	<p>Similarly to <code>EV_H</code>, this macro can be used to override <cite>event.c</cite>'s idea
		2351	of how the <cite>event.h</cite> header can be found.</p>
		2352	</dd>
		2353	<dt>EV_PROTOTYPES</dt>
		2354	<dd>
		2355	<p>If defined to be <code>0</code>, then <cite>ev.h</cite> will not define any function
		2356	prototypes, but still define all the structs and other symbols. This is
		2357	occasionally useful if you want to provide your own wrapper functions
		2358	around libev functions.</p>
		2359	</dd>
		2360	<dt>EV_MULTIPLICITY</dt>
		2361	<dd>
		2362	<p>If undefined or defined to <code>1</code>, then all event-loop-specific functions
		2363	will have the <code>struct ev_loop *</code> as first argument, and you can create
		2364	additional independent event loops. Otherwise there will be no support
		2365	for multiple event loops and there is no first event loop pointer
		2366	argument. Instead, all functions act on the single default loop.</p>
		2367	</dd>
		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>
		2381	</dd>
		2382	<dt>EV_PERIODIC_ENABLE</dt>
		2383	<dd>
		2384	<p>If undefined or defined to be <code>1</code>, then periodic timers are supported. If
		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>
		2429	</dd>
		2430	<dt>EV_COMMON</dt>
		2431	<dd>
		2432	<p>By default, all watchers have a <code>void *data</code> member. By redefining
		2433	this macro to a something else you can include more and other types of
		2434	members. You have to define it each time you include one of the files,
		2435	though, and it must be identical each time.</p>
		2436	<p>For example, the perl EV module uses something like this:</p>
		2437	<pre> #define EV_COMMON \
		2438	SV self; / contains this struct */ \
		2439	SV cb_sv, fh /* note no trailing ";" */
		2440
		2441	</pre>
		2442	</dd>
		2443	<dt>EV_CB_DECLARE (type)</dt>
		2444	<dt>EV_CB_INVOKE (watcher, revents)</dt>
		2445	<dt>ev_set_cb (ev, cb)</dt>
		2446	<dd>
		2447	<p>Can be used to change the callback member declaration in each watcher,
		2448	and the way callbacks are invoked and set. Must expand to a struct member
		2449	definition and a statement, respectively. See the <cite>ev.v</cite> header file for
		2450	their default definitions. One possible use for overriding these is to
		2451	avoid the <code>struct ev_loop *</code> as first argument in all cases, or to use
		2452	method calls instead of plain function calls in C++.</p>
		2453
		2454	</div>
		2455	<h2 id="EXAMPLES">EXAMPLES</h2>
		2456	<div id="EXAMPLES_CONTENT">
		2457	<p>For a real-world example of a program the includes libev
		2458	verbatim, you can have a look at the EV perl module
		2459	(<a href="http://software.schmorp.de/pkg/EV.html">http://software.schmorp.de/pkg/EV.html</a>). It has the libev files in
		2460	the <cite>libev/</cite> subdirectory and includes them in the <cite>EV/EVAPI.h</cite> (public
		2461	interface) and <cite>EV.xs</cite> (implementation) files. Only the <cite>EV.xs</cite> file
		2462	will be compiled. It is pretty complex because it provides its own header
		2463	file.</p>
		2464	<p>The usage in rxvt-unicode is simpler. It has a <cite>ev_cpp.h</cite> header file
		2465	that everybody includes and which overrides some configure choices:</p>
		2466	<pre> #define EV_MINIMAL 1
		2467	#define EV_USE_POLL 0
		2468	#define EV_MULTIPLICITY 0
		2469	#define EV_PERIODIC_ENABLE 0
		2470	#define EV_STAT_ENABLE 0
		2471	#define EV_FORK_ENABLE 0
		2472	#define EV_CONFIG_H <config.h>
		2473	#define EV_MINPRI 0
		2474	#define EV_MAXPRI 0
		2475
		2476	#include "ev++.h"
		2477
		2478	</pre>
		2479	<p>And a <cite>ev_cpp.C</cite> implementation file that contains libev proper and is compiled:</p>
		2480	<pre> #include "ev_cpp.h"
		2481	#include "ev.c"
		2482
		2483
		2484
		2485
		2486	</pre>
		2487
		2488	</div>
		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>
1311	<div id="AUTHOR_CONTENT">	2545	<div id="AUTHOR_CONTENT">
1312	<p>Marc Lehmann <libev@schmorp.de>.</p>	2546	<p>Marc Lehmann <libev@schmorp.de>.</p>
1313		2547
1314	</div>	2548	</div>
1315	</div></body>	2549	</div></body>
1316	</html>	2550	</html>

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Comparing libev/ev.html (file contents): Revision 1.37 by root, Sat Nov 24 07:14:26 2007 UTC vs. Revision 1.79 by root, Wed Dec 12 17:55:30 2007 UTC

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Comparing libev/ev.html (file contents):
Revision 1.37 by root, Sat Nov 24 07:14:26 2007 UTC vs.
Revision 1.79 by root, Wed Dec 12 17:55:30 2007 UTC