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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 18:55:04 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></li>
39	</ul>	70	</ul>
40	</li>	71	</li>
41	<li><a href="#OTHER_FUNCTIONS">OTHER FUNCTIONS</a></li>	72	<li><a href="#OTHER_FUNCTIONS">OTHER FUNCTIONS</a></li>
42	<li><a href="#LIBEVENT_EMULATION">LIBEVENT EMULATION</a></li>	73	<li><a href="#LIBEVENT_EMULATION">LIBEVENT EMULATION</a></li>
43	<li><a href="#C_SUPPORT">C++ SUPPORT</a></li>	74	<li><a href="#C_SUPPORT">C++ SUPPORT</a></li>
		75	<li><a href="#MACRO_MAGIC">MACRO MAGIC</a></li>
		76	<li><a href="#EMBEDDING">EMBEDDING</a>
		77	<ul><li><a href="#FILESETS">FILESETS</a>
		78	<ul><li><a href="#CORE_EVENT_LOOP">CORE EVENT LOOP</a></li>
		79	<li><a href="#LIBEVENT_COMPATIBILITY_API">LIBEVENT COMPATIBILITY API</a></li>
		80	<li><a href="#AUTOCONF_SUPPORT">AUTOCONF SUPPORT</a></li>
		81	</ul>
		82	</li>
		83	<li><a href="#PREPROCESSOR_SYMBOLS_MACROS">PREPROCESSOR SYMBOLS/MACROS</a></li>
		84	<li><a href="#EXAMPLES">EXAMPLES</a></li>
		85	</ul>
		86	</li>
		87	<li><a href="#COMPLEXITIES">COMPLEXITIES</a></li>
44	<li><a href="#AUTHOR">AUTHOR</a>	88	<li><a href="#AUTHOR">AUTHOR</a>
45	</li>	89	</li>
46	</ul><hr />	90	</ul><hr />
47	<!-- INDEX END -->	91	<!-- INDEX END -->
48		92
49	<h1 id="NAME">NAME</h1><p><a href="#TOP" class="toplink">Top</a></p>	93	<h1 id="NAME">NAME</h1>
50	<div id="NAME_CONTENT">	94	<div id="NAME_CONTENT">
51	<p>libev - a high performance full-featured event loop written in C</p>	95	<p>libev - a high performance full-featured event loop written in C</p>
52		96
53	</div>	97	</div>
54	<h1 id="SYNOPSIS">SYNOPSIS</h1><p><a href="#TOP" class="toplink">Top</a></p>	98	<h1 id="SYNOPSIS">SYNOPSIS</h1>
55	<div id="SYNOPSIS_CONTENT">	99	<div id="SYNOPSIS_CONTENT">
56	<pre> #include <ev.h>	100	<pre> #include <ev.h>
57		101
58	</pre>	102	</pre>
59		103
60	</div>	104	</div>
61	<h1 id="DESCRIPTION">DESCRIPTION</h1><p><a href="#TOP" class="toplink">Top</a></p>	105	<h1 id="EXAMPLE_PROGRAM">EXAMPLE PROGRAM</h1>
		106	<div id="EXAMPLE_PROGRAM_CONTENT">
		107	<pre> #include <ev.h>
		108
		109	ev_io stdin_watcher;
		110	ev_timer timeout_watcher;
		111
		112	/* called when data readable on stdin */
		113	static void
		114	stdin_cb (EV_P_ struct ev_io *w, int revents)
		115	{
		116	/* puts ("stdin ready"); */
		117	ev_io_stop (EV_A_ w); /* just a syntax example */
		118	ev_unloop (EV_A_ EVUNLOOP_ALL); /* leave all loop calls */
		119	}
		120
		121	static void
		122	timeout_cb (EV_P_ struct ev_timer *w, int revents)
		123	{
		124	/* puts ("timeout"); */
		125	ev_unloop (EV_A_ EVUNLOOP_ONE); /* leave one loop call */
		126	}
		127
		128	int
		129	main (void)
		130	{
		131	struct ev_loop *loop = ev_default_loop (0);
		132
		133	/* initialise an io watcher, then start it */
		134	ev_io_init (&stdin_watcher, stdin_cb, /STDIN_FILENO/ 0, EV_READ);
		135	ev_io_start (loop, &stdin_watcher);
		136
		137	/* simple non-repeating 5.5 second timeout */
		138	ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.);
		139	ev_timer_start (loop, &timeout_watcher);
		140
		141	/* loop till timeout or data ready */
		142	ev_loop (loop, 0);
		143
		144	return 0;
		145	}
		146
		147	</pre>
		148
		149	</div>
		150	<h1 id="DESCRIPTION">DESCRIPTION</h1>
62	<div id="DESCRIPTION_CONTENT">	151	<div id="DESCRIPTION_CONTENT">
		152	<p>The newest version of this document is also available as a html-formatted
		153	web page you might find easier to navigate when reading it for the first
		154	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	155	<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	156	file descriptor being readable or a timeout occuring), and it will manage
65	these event sources and provide your program with events.</p>	157	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	158	<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	159	(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	162	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	163	details of the event, and then hand it over to libev by <i>starting</i> the
72	watcher.</p>	164	watcher.</p>
73		165
74	</div>	166	</div>
75	<h1 id="FEATURES">FEATURES</h1><p><a href="#TOP" class="toplink">Top</a></p>	167	<h1 id="FEATURES">FEATURES</h1>
76	<div id="FEATURES_CONTENT">	168	<div id="FEATURES_CONTENT">
77	<p>Libev supports select, poll, the linux-specific epoll and the bsd-specific	169	<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	170	BSD-specific <code>kqueue</code> and the Solaris-specific event port mechanisms
79	timers with customised rescheduling, signal events, process status change	171	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	172	(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	173	with customised rescheduling (<code>ev_periodic</code>), synchronous signals
		174	(<code>ev_signal</code>), process status change events (<code>ev_child</code>), and event
		175	watchers dealing with the event loop mechanism itself (<code>ev_idle</code>,
		176	<code>ev_embed</code>, <code>ev_prepare</code> and <code>ev_check</code> watchers) as well as
		177	file watchers (<code>ev_stat</code>) and even limited support for fork events
		178	(<code>ev_fork</code>).</p>
		179	<p>It also is quite fast (see this
82	fast (see this <a href="http://libev.schmorp.de/bench.html">benchmark</a> comparing	180	<a href="http://libev.schmorp.de/bench.html">benchmark</a> comparing it to libevent
83	it to libevent for example).</p>	181	for example).</p>
84		182
85	</div>	183	</div>
86	<h1 id="CONVENTIONS">CONVENTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p>	184	<h1 id="CONVENTIONS">CONVENTIONS</h1>
87	<div id="CONVENTIONS_CONTENT">	185	<div id="CONVENTIONS_CONTENT">
88	<p>Libev is very configurable. In this manual the default configuration	186	<p>Libev is very configurable. In this manual the default configuration will
89	will be described, which supports multiple event loops. For more info	187	be described, which supports multiple event loops. For more info about
90	about various configuration options please have a look at the file	188	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	189	this manual. If libev was configured without support for multiple event
92	support for multiple event loops, then all functions taking an initial	190	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>)	191	(which is always of type <code>struct ev_loop *</code>) will not have this argument.</p>
94	will not have this argument.</p>
95		192
96	</div>	193	</div>
97	<h1 id="TIME_REPRESENTATION">TIME REPRESENTATION</h1><p><a href="#TOP" class="toplink">Top</a></p>	194	<h1 id="TIME_REPRESENTATION">TIME REPRESENTATION</h1>
98	<div id="TIME_REPRESENTATION_CONTENT">	195	<div id="TIME_REPRESENTATION_CONTENT">
99	<p>Libev represents time as a single floating point number, representing the	196	<p>Libev represents time as a single floating point number, representing the
100	(fractional) number of seconds since the (POSIX) epoch (somewhere near	197	(fractional) number of seconds since the (POSIX) epoch (somewhere near
101	the beginning of 1970, details are complicated, don't ask). This type is	198	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	199	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	200	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>	201	it, you should treat it as such.</p>
105		202
106
107
108
109
110	</div>	203	</div>
111	<h1 id="GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p>	204	<h1 id="GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</h1>
112	<div id="GLOBAL_FUNCTIONS_CONTENT">	205	<div id="GLOBAL_FUNCTIONS_CONTENT">
113	<p>These functions can be called anytime, even before initialising the	206	<p>These functions can be called anytime, even before initialising the
114	library in any way.</p>	207	library in any way.</p>
115	<dl>	208	<dl>
116	<dt>ev_tstamp ev_time ()</dt>	209	<dt>ev_tstamp ev_time ()</dt>
…		…
120	you actually want to know.</p>	213	you actually want to know.</p>
121	</dd>	214	</dd>
122	<dt>int ev_version_major ()</dt>	215	<dt>int ev_version_major ()</dt>
123	<dt>int ev_version_minor ()</dt>	216	<dt>int ev_version_minor ()</dt>
124	<dd>	217	<dd>
125	<p>You can find out the major and minor version numbers of the library	218	<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	219	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	220	<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	221	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>	222	version of the library your program was compiled against.</p>
		223	<p>These version numbers refer to the ABI version of the library, not the
		224	release version.</p>
130	<p>Usually, it's a good idea to terminate if the major versions mismatch,	225	<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	226	as this indicates an incompatible change. Minor versions are usually
132	compatible to older versions, so a larger minor version alone is usually	227	compatible to older versions, so a larger minor version alone is usually
133	not a problem.</p>	228	not a problem.</p>
134	<p>Example: make sure we haven't accidentally been linked against the wrong	229	<p>Example: Make sure we haven't accidentally been linked against the wrong
135	version:</p>	230	version.</p>
136	<pre> assert (("libev version mismatch",	231	<pre> assert (("libev version mismatch",
137	ev_version_major () == EV_VERSION_MAJOR	232	ev_version_major () == EV_VERSION_MAJOR
138	&& ev_version_minor () >= EV_VERSION_MINOR));	233	&& ev_version_minor () >= EV_VERSION_MINOR));
139		234
140	</pre>	235	</pre>
…		…
170	recommended ones.</p>	265	recommended ones.</p>
171	<p>See the description of <code>ev_embed</code> watchers for more info.</p>	266	<p>See the description of <code>ev_embed</code> watchers for more info.</p>
172	</dd>	267	</dd>
173	<dt>ev_set_allocator (void (cb)(void *ptr, long size))</dt>	268	<dt>ev_set_allocator (void (cb)(void *ptr, long size))</dt>
174	<dd>	269	<dd>
175	<p>Sets the allocation function to use (the prototype is similar to the	270	<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	271	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	272	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	273	memory needs to be allocated, the library might abort or take some
179	destructive action. The default is your system realloc function.</p>	274	potentially destructive action. The default is your system realloc
		275	function.</p>
180	<p>You could override this function in high-availability programs to, say,	276	<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,	277	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>	278	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	279	<p>Example: Replace the libev allocator with one that waits a bit and then
184	retries: better than mine).</p>	280	retries).</p>
185	<pre> static void *	281	<pre> static void *
186	persistent_realloc (void *ptr, long size)	282	persistent_realloc (void *ptr, size_t size)
187	{	283	{
188	for (;;)	284	for (;;)
189	{	285	{
190	void *newptr = realloc (ptr, size);	286	void *newptr = realloc (ptr, size);
191		287
…		…
208	indicating the system call or subsystem causing the problem. If this	304	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	305	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	306	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	307	requested operation, or, if the condition doesn't go away, do bad stuff
212	(such as abort).</p>	308	(such as abort).</p>
213	<p>Example: do the same thing as libev does internally:</p>	309	<p>Example: This is basically the same thing that libev does internally, too.</p>
214	<pre> static void	310	<pre> static void
215	fatal_error (const char *msg)	311	fatal_error (const char *msg)
216	{	312	{
217	perror (msg);	313	perror (msg);
218	abort ();	314	abort ();
…		…
224	</pre>	320	</pre>
225	</dd>	321	</dd>
226	</dl>	322	</dl>
227		323
228	</div>	324	</div>
229	<h1 id="FUNCTIONS_CONTROLLING_THE_EVENT_LOOP">FUNCTIONS CONTROLLING THE EVENT LOOP</h1><p><a href="#TOP" class="toplink">Top</a></p>	325	<h1 id="FUNCTIONS_CONTROLLING_THE_EVENT_LOOP">FUNCTIONS CONTROLLING THE EVENT LOOP</h1>
230	<div id="FUNCTIONS_CONTROLLING_THE_EVENT_LOOP-2">	326	<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	327	<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	328	types of such loops, the <i>default</i> loop, which supports signals and child
233	events, and dynamically created loops which do not.</p>	329	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	330	<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	359	<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	360	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	361	useful to try out specific backends to test their performance, or to work
266	around bugs.</p>	362	around bugs.</p>
267	</dd>	363	</dd>
		364	<dt><code>EVFLAG_FORKCHECK</code></dt>
		365	<dd>
		366	<p>Instead of calling <code>ev_default_fork</code> or <code>ev_loop_fork</code> manually after
		367	a fork, you can also make libev check for a fork in each iteration by
		368	enabling this flag.</p>
		369	<p>This works by calling <code>getpid ()</code> on every iteration of the loop,
		370	and thus this might slow down your event loop if you do a lot of loop
		371	iterations and little real work, but is usually not noticeable (on my
		372	Linux system for example, <code>getpid</code> is actually a simple 5-insn sequence
		373	without a syscall and thus <i>very</i> fast, but my Linux system also has
		374	<code>pthread_atfork</code> which is even faster).</p>
		375	<p>The big advantage of this flag is that you can forget about fork (and
		376	forget about forgetting to tell libev about forking) when you use this
		377	flag.</p>
		378	<p>This flag setting cannot be overriden or specified in the <code>LIBEV_FLAGS</code>
		379	environment variable.</p>
		380	</dd>
268	<dt><code>EVBACKEND_SELECT</code> (value 1, portable select backend)</dt>	381	<dt><code>EVBACKEND_SELECT</code> (value 1, portable select backend)</dt>
269	<dd>	382	<dd>
270	<p>This is your standard select(2) backend. Not <i>completely</i> standard, as	383	<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,	384	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	385	but if that fails, expect a fairly low limit on the number of fds when
…		…
354	<dd>	467	<dd>
355	<p>Similar to <code>ev_default_loop</code>, but always creates a new event loop that is	468	<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	469	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	470	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>	471	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>	472	<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);	473	<pre> struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL \| EVFLAG_NOENV);
361	if (!epoller)	474	if (!epoller)
362	fatal ("no epoll found here, maybe it hides under your chair");	475	fatal ("no epoll found here, maybe it hides under your chair");
363		476
364	</pre>	477	</pre>
365	</dd>	478	</dd>
366	<dt>ev_default_destroy ()</dt>	479	<dt>ev_default_destroy ()</dt>
367	<dd>	480	<dd>
368	<p>Destroys the default loop again (frees all memory and kernel state	481	<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	482	etc.). None of the active event watchers will be stopped in the normal
370	any way whatsoever, although you cannot rely on this :).</p>	483	sense, so e.g. <code>ev_is_active</code> might still return true. It is your
		484	responsibility to either stop all watchers cleanly yoursef <i>before</i>
		485	calling this function, or cope with the fact afterwards (which is usually
		486	the easiest thing, youc na just ignore the watchers and/or <code>free ()</code> them
		487	for example).</p>
371	</dd>	488	</dd>
372	<dt>ev_loop_destroy (loop)</dt>	489	<dt>ev_loop_destroy (loop)</dt>
373	<dd>	490	<dd>
374	<p>Like <code>ev_default_destroy</code>, but destroys an event loop created by an	491	<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>	492	earlier call to <code>ev_loop_new</code>.</p>
…		…
396	<dt>ev_loop_fork (loop)</dt>	513	<dt>ev_loop_fork (loop)</dt>
397	<dd>	514	<dd>
398	<p>Like <code>ev_default_fork</code>, but acts on an event loop created by	515	<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	516	<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>	517	after fork, and how you do this is entirely your own problem.</p>
		518	</dd>
		519	<dt>unsigned int ev_loop_count (loop)</dt>
		520	<dd>
		521	<p>Returns the count of loop iterations for the loop, which is identical to
		522	the number of times libev did poll for new events. It starts at <code>0</code> and
		523	happily wraps around with enough iterations.</p>
		524	<p>This value can sometimes be useful as a generation counter of sorts (it
		525	"ticks" the number of loop iterations), as it roughly corresponds with
		526	<code>ev_prepare</code> and <code>ev_check</code> calls.</p>
401	</dd>	527	</dd>
402	<dt>unsigned int ev_backend (loop)</dt>	528	<dt>unsigned int ev_backend (loop)</dt>
403	<dd>	529	<dd>
404	<p>Returns one of the <code>EVBACKEND_*</code> flags indicating the event backend in	530	<p>Returns one of the <code>EVBACKEND_*</code> flags indicating the event backend in
405	use.</p>	531	use.</p>
…		…
433	one iteration of the loop. This is useful if you are waiting for some	559	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	560	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	561	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>	562	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>	563	<p>Here are the gory details of what <code>ev_loop</code> does:</p>
		564	<pre> - Before the first iteration, call any pending watchers.
438	<pre> * If there are no active watchers (reference count is zero), return.	565	* If there are no active watchers (reference count is zero), return.
439	- Queue prepare watchers and then call all outstanding watchers.	566	- Queue all prepare watchers and then call all outstanding watchers.
440	- If we have been forked, recreate the kernel state.	567	- If we have been forked, recreate the kernel state.
441	- Update the kernel state with all outstanding changes.	568	- Update the kernel state with all outstanding changes.
442	- Update the "event loop time".	569	- Update the "event loop time".
443	- Calculate for how long to block.	570	- Calculate for how long to block.
444	- Block the process, waiting for any events.	571	- Block the process, waiting for any events.
…		…
453	be handled here by queueing them when their watcher gets executed.	580	be handled here by queueing them when their watcher gets executed.
454	- If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK	581	- If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK
455	were used, return, otherwise continue with step *.	582	were used, return, otherwise continue with step *.
456		583
457	</pre>	584	</pre>
458	<p>Example: queue some jobs and then loop until no events are outsanding	585	<p>Example: Queue some jobs and then loop until no events are outsanding
459	anymore.</p>	586	anymore.</p>
460	<pre> ... queue jobs here, make sure they register event watchers as long	587	<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..)	588	... as they still have work to do (even an idle watcher will do..)
462	ev_loop (my_loop, 0);	589	ev_loop (my_loop, 0);
463	... jobs done. yeah!	590	... jobs done. yeah!
…		…
482	example, libev itself uses this for its internal signal pipe: It is not	609	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	610	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	611	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	612	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>	613	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>	614	<p>Example: Create a signal watcher, but keep it from keeping <code>ev_loop</code>
488	running when nothing else is active.</p>	615	running when nothing else is active.</p>
489	<pre> struct dv_signal exitsig;	616	<pre> struct ev_signal exitsig;
490	ev_signal_init (&exitsig, sig_cb, SIGINT);	617	ev_signal_init (&exitsig, sig_cb, SIGINT);
491	ev_signal_start (myloop, &exitsig);	618	ev_signal_start (loop, &exitsig);
492	evf_unref (myloop);	619	evf_unref (loop);
493		620
494	</pre>	621	</pre>
495	<p>Example: for some weird reason, unregister the above signal handler again.</p>	622	<p>Example: For some weird reason, unregister the above signal handler again.</p>
496	<pre> ev_ref (myloop);	623	<pre> ev_ref (loop);
497	ev_signal_stop (myloop, &exitsig);	624	ev_signal_stop (loop, &exitsig);
498		625
499	</pre>	626	</pre>
500	</dd>	627	</dd>
501	</dl>	628	</dl>
502		629
		630
		631
		632
		633
503	</div>	634	</div>
504	<h1 id="ANATOMY_OF_A_WATCHER">ANATOMY OF A WATCHER</h1><p><a href="#TOP" class="toplink">Top</a></p>	635	<h1 id="ANATOMY_OF_A_WATCHER">ANATOMY OF A WATCHER</h1>
505	<div id="ANATOMY_OF_A_WATCHER_CONTENT">	636	<div id="ANATOMY_OF_A_WATCHER_CONTENT">
506	<p>A watcher is a structure that you create and register to record your	637	<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	638	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>	639	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)	640	<pre> static void my_cb (struct ev_loop loop, struct ev_io w, int revents)
…		…
566	</dd>	697	</dd>
567	<dt><code>EV_CHILD</code></dt>	698	<dt><code>EV_CHILD</code></dt>
568	<dd>	699	<dd>
569	<p>The pid specified in the <code>ev_child</code> watcher has received a status change.</p>	700	<p>The pid specified in the <code>ev_child</code> watcher has received a status change.</p>
570	</dd>	701	</dd>
		702	<dt><code>EV_STAT</code></dt>
		703	<dd>
		704	<p>The path specified in the <code>ev_stat</code> watcher changed its attributes somehow.</p>
		705	</dd>
571	<dt><code>EV_IDLE</code></dt>	706	<dt><code>EV_IDLE</code></dt>
572	<dd>	707	<dd>
573	<p>The <code>ev_idle</code> watcher has determined that you have nothing better to do.</p>	708	<p>The <code>ev_idle</code> watcher has determined that you have nothing better to do.</p>
574	</dd>	709	</dd>
575	<dt><code>EV_PREPARE</code></dt>	710	<dt><code>EV_PREPARE</code></dt>
…		…
580	<code>ev_loop</code> has gathered them, but before it invokes any callbacks for any	715	<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	716	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	717	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	718	(for example, a <code>ev_prepare</code> watcher might start an idle watcher to keep
584	<code>ev_loop</code> from blocking).</p>	719	<code>ev_loop</code> from blocking).</p>
		720	</dd>
		721	<dt><code>EV_EMBED</code></dt>
		722	<dd>
		723	<p>The embedded event loop specified in the <code>ev_embed</code> watcher needs attention.</p>
		724	</dd>
		725	<dt><code>EV_FORK</code></dt>
		726	<dd>
		727	<p>The event loop has been resumed in the child process after fork (see
		728	<code>ev_fork</code>).</p>
585	</dd>	729	</dd>
586	<dt><code>EV_ERROR</code></dt>	730	<dt><code>EV_ERROR</code></dt>
587	<dd>	731	<dd>
588	<p>An unspecified error has occured, the watcher has been stopped. This might	732	<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	733	happen because the watcher could not be properly started because libev
…		…
597	programs, though, so beware.</p>	741	programs, though, so beware.</p>
598	</dd>	742	</dd>
599	</dl>	743	</dl>
600		744
601	</div>	745	</div>
602	<h2 id="SUMMARY_OF_GENERIC_WATCHER_FUNCTIONS">SUMMARY OF GENERIC WATCHER FUNCTIONS</h2>	746	<h2 id="GENERIC_WATCHER_FUNCTIONS">GENERIC WATCHER FUNCTIONS</h2>
603	<div id="SUMMARY_OF_GENERIC_WATCHER_FUNCTIONS-2">	747	<div id="GENERIC_WATCHER_FUNCTIONS_CONTENT">
604	<p>In the following description, <code>TYPE</code> stands for the watcher type,	748	<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>	749	e.g. <code>timer</code> for <code>ev_timer</code> watchers and <code>io</code> for <code>ev_io</code> watchers.</p>
606	<dl>	750	<dl>
607	<dt><code>ev_init</code> (ev_TYPE *watcher, callback)</dt>	751	<dt><code>ev_init</code> (ev_TYPE *watcher, callback)</dt>
608	<dd>	752	<dd>
…		…
612	the type-specific <code>ev_TYPE_set</code> macro afterwards to initialise the	756	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	757	type-specific parts. For each type there is also a <code>ev_TYPE_init</code> macro
614	which rolls both calls into one.</p>	758	which rolls both calls into one.</p>
615	<p>You can reinitialise a watcher at any time as long as it has been stopped	759	<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>	760	(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,	761	<p>The callback is always of type <code>void ()(ev_loop loop, ev_TYPE *watcher,
618	int revents)</code>.</p>	762	int revents)</code>.</p>
619	</dd>	763	</dd>
620	<dt><code>ev_TYPE_set</code> (ev_TYPE *, [args])</dt>	764	<dt><code>ev_TYPE_set</code> (ev_TYPE *, [args])</dt>
621	<dd>	765	<dd>
622	<p>This macro initialises the type-specific parts of a watcher. You need to	766	<p>This macro initialises the type-specific parts of a watcher. You need to
…		…
656	<dt>bool ev_is_pending (ev_TYPE *watcher)</dt>	800	<dt>bool ev_is_pending (ev_TYPE *watcher)</dt>
657	<dd>	801	<dd>
658	<p>Returns a true value iff the watcher is pending, (i.e. it has outstanding	802	<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	803	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	804	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	805	<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>	806	make sure the watcher is available to libev (e.g. you cannot <code>free ()</code>
		807	it).</p>
663	</dd>	808	</dd>
664	<dt>callback = ev_cb (ev_TYPE *watcher)</dt>	809	<dt>callback ev_cb (ev_TYPE *watcher)</dt>
665	<dd>	810	<dd>
666	<p>Returns the callback currently set on the watcher.</p>	811	<p>Returns the callback currently set on the watcher.</p>
667	</dd>	812	</dd>
668	<dt>ev_cb_set (ev_TYPE *watcher, callback)</dt>	813	<dt>ev_cb_set (ev_TYPE *watcher, callback)</dt>
669	<dd>	814	<dd>
670	<p>Change the callback. You can change the callback at virtually any time	815	<p>Change the callback. You can change the callback at virtually any time
671	(modulo threads).</p>	816	(modulo threads).</p>
		817	</dd>
		818	<dt>ev_set_priority (ev_TYPE *watcher, priority)</dt>
		819	<dt>int ev_priority (ev_TYPE *watcher)</dt>
		820	<dd>
		821	<p>Set and query the priority of the watcher. The priority is a small
		822	integer between <code>EV_MAXPRI</code> (default: <code>2</code>) and <code>EV_MINPRI</code>
		823	(default: <code>-2</code>). Pending watchers with higher priority will be invoked
		824	before watchers with lower priority, but priority will not keep watchers
		825	from being executed (except for <code>ev_idle</code> watchers).</p>
		826	<p>This means that priorities are <i>only</i> used for ordering callback
		827	invocation after new events have been received. This is useful, for
		828	example, to reduce latency after idling, or more often, to bind two
		829	watchers on the same event and make sure one is called first.</p>
		830	<p>If you need to suppress invocation when higher priority events are pending
		831	you need to look at <code>ev_idle</code> watchers, which provide this functionality.</p>
		832	<p>You <i>must not</i> change the priority of a watcher as long as it is active or
		833	pending.</p>
		834	<p>The default priority used by watchers when no priority has been set is
		835	always <code>0</code>, which is supposed to not be too high and not be too low :).</p>
		836	<p>Setting a priority outside the range of <code>EV_MINPRI</code> to <code>EV_MAXPRI</code> is
		837	fine, as long as you do not mind that the priority value you query might
		838	or might not have been adjusted to be within valid range.</p>
		839	</dd>
		840	<dt>ev_invoke (loop, ev_TYPE *watcher, int revents)</dt>
		841	<dd>
		842	<p>Invoke the <code>watcher</code> with the given <code>loop</code> and <code>revents</code>. Neither
		843	<code>loop</code> nor <code>revents</code> need to be valid as long as the watcher callback
		844	can deal with that fact.</p>
		845	</dd>
		846	<dt>int ev_clear_pending (loop, ev_TYPE *watcher)</dt>
		847	<dd>
		848	<p>If the watcher is pending, this function returns clears its pending status
		849	and returns its <code>revents</code> bitset (as if its callback was invoked). If the
		850	watcher isn't pending it does nothing and returns <code>0</code>.</p>
672	</dd>	851	</dd>
673	</dl>	852	</dl>
674		853
675		854
676		855
…		…
701	struct my_io w = (struct my_io )w_;	880	struct my_io w = (struct my_io )w_;
702	...	881	...
703	}	882	}
704		883
705	</pre>	884	</pre>
706	<p>More interesting and less C-conformant ways of catsing your callback type	885	<p>More interesting and less C-conformant ways of casting your callback type
707	have been omitted....</p>	886	instead have been omitted.</p>
		887	<p>Another common scenario is having some data structure with multiple
		888	watchers:</p>
		889	<pre> struct my_biggy
		890	{
		891	int some_data;
		892	ev_timer t1;
		893	ev_timer t2;
		894	}
708		895
		896	</pre>
		897	<p>In this case getting the pointer to <code>my_biggy</code> is a bit more complicated,
		898	you need to use <code>offsetof</code>:</p>
		899	<pre> #include <stddef.h>
709		900
		901	static void
		902	t1_cb (EV_P_ struct ev_timer *w, int revents)
		903	{
		904	struct my_biggy big = (struct my_biggy *
		905	(((char *)w) - offsetof (struct my_biggy, t1));
		906	}
710		907
		908	static void
		909	t2_cb (EV_P_ struct ev_timer *w, int revents)
		910	{
		911	struct my_biggy big = (struct my_biggy *
		912	(((char *)w) - offsetof (struct my_biggy, t2));
		913	}
711		914
712		915
		916
		917
		918	</pre>
		919
713	</div>	920	</div>
714	<h1 id="WATCHER_TYPES">WATCHER TYPES</h1><p><a href="#TOP" class="toplink">Top</a></p>	921	<h1 id="WATCHER_TYPES">WATCHER TYPES</h1>
715	<div id="WATCHER_TYPES_CONTENT">	922	<div id="WATCHER_TYPES_CONTENT">
716	<p>This section describes each watcher in detail, but will not repeat	923	<p>This section describes each watcher in detail, but will not repeat
717	information given in the last section.</p>	924	information given in the last section. Any initialisation/set macros,
		925	functions and members specific to the watcher type are explained.</p>
		926	<p>Members are additionally marked with either <i>[read-only]</i>, meaning that,
		927	while the watcher is active, you can look at the member and expect some
		928	sensible content, but you must not modify it (you can modify it while the
		929	watcher is stopped to your hearts content), or <i>[read-write]</i>, which
		930	means you can expect it to have some sensible content while the watcher
		931	is active, but you can also modify it. Modifying it may not do something
		932	sensible or take immediate effect (or do anything at all), but libev will
		933	not crash or malfunction in any way.</p>
718		934
719		935
720		936
721		937
722		938
723	</div>	939	</div>
724	<h2 id="code_ev_io_code_is_this_file_descrip"><code>ev_io</code> - is this file descriptor readable or writable</h2>	940	<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">	941	<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	942	<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	943	in each iteration of the event loop, or, more precisely, when reading
728	level-triggering because you keep receiving events as long as the	944	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	945	some data. This behaviour is called level-triggering because you keep
730	act on the event and neither want to receive future events).</p>	946	receiving events as long as the condition persists. Remember you can stop
		947	the watcher if you don't want to act on the event and neither want to
		948	receive future events.</p>
731	<p>In general you can register as many read and/or write event watchers per	949	<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	950	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	951	descriptors to non-blocking mode is also usually a good idea (but not
734	required if you know what you are doing).</p>	952	required if you know what you are doing).</p>
735	<p>You have to be careful with dup'ed file descriptors, though. Some backends	953	<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	954	(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	955	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	956	to the same underlying file/socket/etc. description (that is, they share
739	the same underlying "file open").</p>	957	the same underlying "file open").</p>
740	<p>If you must do this, then force the use of a known-to-be-good backend	958	<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	959	(at the time of this writing, this includes only <code>EVBACKEND_SELECT</code> and
742	<code>EVBACKEND_POLL</code>).</p>	960	<code>EVBACKEND_POLL</code>).</p>
		961	<p>Another thing you have to watch out for is that it is quite easy to
		962	receive "spurious" readyness notifications, that is your callback might
		963	be called with <code>EV_READ</code> but a subsequent <code>read</code>(2) will actually block
		964	because there is no data. Not only are some backends known to create a
		965	lot of those (for example solaris ports), it is very easy to get into
		966	this situation even with a relatively standard program structure. Thus
		967	it is best to always use non-blocking I/O: An extra <code>read</code>(2) returning
		968	<code>EAGAIN</code> is far preferable to a program hanging until some data arrives.</p>
		969	<p>If you cannot run the fd in non-blocking mode (for example you should not
		970	play around with an Xlib connection), then you have to seperately re-test
		971	whether a file descriptor is really ready with a known-to-be good interface
		972	such as poll (fortunately in our Xlib example, Xlib already does this on
		973	its own, so its quite safe to use).</p>
		974
		975	</div>
		976	<h3 id="The_special_problem_of_disappearing_">The special problem of disappearing file descriptors</h3>
		977	<div id="The_special_problem_of_disappearing_-2">
		978	<p>Some backends (e.g kqueue, epoll) need to be told about closing a file
		979	descriptor (either by calling <code>close</code> explicitly or by any other means,
		980	such as <code>dup</code>). The reason is that you register interest in some file
		981	descriptor, but when it goes away, the operating system will silently drop
		982	this interest. If another file descriptor with the same number then is
		983	registered with libev, there is no efficient way to see that this is, in
		984	fact, a different file descriptor.</p>
		985	<p>To avoid having to explicitly tell libev about such cases, libev follows
		986	the following policy: Each time <code>ev_io_set</code> is being called, libev
		987	will assume that this is potentially a new file descriptor, otherwise
		988	it is assumed that the file descriptor stays the same. That means that
		989	you <i>have</i> to call <code>ev_io_set</code> (or <code>ev_io_init</code>) when you change the
		990	descriptor even if the file descriptor number itself did not change.</p>
		991	<p>This is how one would do it normally anyway, the important point is that
		992	the libev application should not optimise around libev but should leave
		993	optimisations to libev.</p>
		994
		995
		996
		997
		998
		999	</div>
		1000	<h3 id="Watcher_Specific_Functions">Watcher-Specific Functions</h3>
		1001	<div id="Watcher_Specific_Functions_CONTENT">
743	<dl>	1002	<dl>
744	<dt>ev_io_init (ev_io *, callback, int fd, int events)</dt>	1003	<dt>ev_io_init (ev_io *, callback, int fd, int events)</dt>
745	<dt>ev_io_set (ev_io *, int fd, int events)</dt>	1004	<dt>ev_io_set (ev_io *, int fd, int events)</dt>
746	<dd>	1005	<dd>
747	<p>Configures an <code>ev_io</code> watcher. The fd is the file descriptor to rceeive	1006	<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 \|	1007	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>	1008	<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	1009	</dd>
751	epoll and solaris ports) can result in spurious readyness notifications	1010	<dt>int fd [read-only]</dt>
752	for file descriptors, so you practically need to use non-blocking I/O (and	1011	<dd>
753	treat callback invocation as hint only), or retest separately with a safe	1012	<p>The file descriptor being watched.</p>
754	interface before doing I/O (XLib can do this), or force the use of either	1013	</dd>
755	<code>EVBACKEND_SELECT</code> or <code>EVBACKEND_POLL</code>, which don't suffer from this	1014	<dt>int events [read-only]</dt>
756	problem. Also note that it is quite easy to have your callback invoked	1015	<dd>
757	when the readyness condition is no longer valid even when employing	1016	<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>	1017	</dd>
761	</dl>	1018	</dl>
762	<p>Example: call <code>stdin_readable_cb</code> when STDIN_FILENO has become, well	1019	<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	1020	readable, but only once. Since it is likely line-buffered, you could
764	attempt to read a whole line in the callback:</p>	1021	attempt to read a whole line in the callback.</p>
765	<pre> static void	1022	<pre> static void
766	stdin_readable_cb (struct ev_loop loop, struct ev_io w, int revents)	1023	stdin_readable_cb (struct ev_loop loop, struct ev_io w, int revents)
767	{	1024	{
768	ev_io_stop (loop, w);	1025	ev_io_stop (loop, w);
769	.. read from stdin here (or from w->fd) and haqndle any I/O errors	1026	.. read from stdin here (or from w->fd) and haqndle any I/O errors
…		…
780		1037
781		1038
782	</pre>	1039	</pre>
783		1040
784	</div>	1041	</div>
785	<h2 id="code_ev_timer_code_relative_and_opti"><code>ev_timer</code> - relative and optionally recurring timeouts</h2>	1042	<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">	1043	<div id="code_ev_timer_code_relative_and_opti-2">
787	<p>Timer watchers are simple relative timers that generate an event after a	1044	<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>	1045	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	1046	<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	1047	times out after an hour and you reset your system clock to last years
…		…
800		1057
801	</pre>	1058	</pre>
802	<p>The callback is guarenteed to be invoked only when its timeout has passed,	1059	<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	1060	but if multiple timers become ready during the same loop iteration then
804	order of execution is undefined.</p>	1061	order of execution is undefined.</p>
		1062
		1063	</div>
		1064	<h3 id="Watcher_Specific_Functions_and_Data_">Watcher-Specific Functions and Data Members</h3>
		1065	<div id="Watcher_Specific_Functions_and_Data_-2">
805	<dl>	1066	<dl>
806	<dt>ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)</dt>	1067	<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>	1068	<dt>ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)</dt>
808	<dd>	1069	<dd>
809	<p>Configure the timer to trigger after <code>after</code> seconds. If <code>repeat</code> is	1070	<p>Configure the timer to trigger after <code>after</code> seconds. If <code>repeat</code> is
…		…
818	</dd>	1079	</dd>
819	<dt>ev_timer_again (loop)</dt>	1080	<dt>ev_timer_again (loop)</dt>
820	<dd>	1081	<dd>
821	<p>This will act as if the timer timed out and restart it again if it is	1082	<p>This will act as if the timer timed out and restart it again if it is
822	repeating. The exact semantics are:</p>	1083	repeating. The exact semantics are:</p>
		1084	<p>If the timer is pending, its pending status is cleared.</p>
823	<p>If the timer is started but nonrepeating, stop it.</p>	1085	<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	1086	<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>	1087	<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	1088	<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	1089	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	1090	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	1091	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	1092	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	1093	<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	1094	you go into an idle state where you do not expect data to travel on the
		1095	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>	1096	automatically restart it if need be.</p>
		1097	<p>That means you can ignore the <code>after</code> value and <code>ev_timer_start</code>
		1098	altogether and only ever use the <code>repeat</code> value and <code>ev_timer_again</code>:</p>
		1099	<pre> ev_timer_init (timer, callback, 0., 5.);
		1100	ev_timer_again (loop, timer);
		1101	...
		1102	timer->again = 17.;
		1103	ev_timer_again (loop, timer);
		1104	...
		1105	timer->again = 10.;
		1106	ev_timer_again (loop, timer);
		1107
		1108	</pre>
		1109	<p>This is more slightly efficient then stopping/starting the timer each time
		1110	you want to modify its timeout value.</p>
		1111	</dd>
		1112	<dt>ev_tstamp repeat [read-write]</dt>
		1113	<dd>
		1114	<p>The current <code>repeat</code> value. Will be used each time the watcher times out
		1115	or <code>ev_timer_again</code> is called and determines the next timeout (if any),
		1116	which is also when any modifications are taken into account.</p>
834	</dd>	1117	</dd>
835	</dl>	1118	</dl>
836	<p>Example: create a timer that fires after 60 seconds.</p>	1119	<p>Example: Create a timer that fires after 60 seconds.</p>
837	<pre> static void	1120	<pre> static void
838	one_minute_cb (struct ev_loop loop, struct ev_timer w, int revents)	1121	one_minute_cb (struct ev_loop loop, struct ev_timer w, int revents)
839	{	1122	{
840	.. one minute over, w is actually stopped right here	1123	.. one minute over, w is actually stopped right here
841	}	1124	}
…		…
843	struct ev_timer mytimer;	1126	struct ev_timer mytimer;
844	ev_timer_init (&mytimer, one_minute_cb, 60., 0.);	1127	ev_timer_init (&mytimer, one_minute_cb, 60., 0.);
845	ev_timer_start (loop, &mytimer);	1128	ev_timer_start (loop, &mytimer);
846		1129
847	</pre>	1130	</pre>
848	<p>Example: create a timeout timer that times out after 10 seconds of	1131	<p>Example: Create a timeout timer that times out after 10 seconds of
849	inactivity.</p>	1132	inactivity.</p>
850	<pre> static void	1133	<pre> static void
851	timeout_cb (struct ev_loop loop, struct ev_timer w, int revents)	1134	timeout_cb (struct ev_loop loop, struct ev_timer w, int revents)
852	{	1135	{
853	.. ten seconds without any activity	1136	.. ten seconds without any activity
…		…
866		1149
867		1150
868	</pre>	1151	</pre>
869		1152
870	</div>	1153	</div>
871	<h2 id="code_ev_periodic_code_to_cron_or_not"><code>ev_periodic</code> - to cron or not to cron</h2>	1154	<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">	1155	<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	1156	<p>Periodic watchers are also timers of a kind, but they are very versatile
874	(and unfortunately a bit complex).</p>	1157	(and unfortunately a bit complex).</p>
875	<p>Unlike <code>ev_timer</code>'s, they are not based on real time (or relative time)	1158	<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	1159	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	1160	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 ()	1161	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	1162	+ 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	1163	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	1164	roughly 10 seconds later).</p>
882	again).</p>
883	<p>They can also be used to implement vastly more complex timers, such as	1165	<p>They can also be used to implement vastly more complex timers, such as
884	triggering an event on eahc midnight, local time.</p>	1166	triggering an event on each midnight, local time or other, complicated,
		1167	rules.</p>
885	<p>As with timers, the callback is guarenteed to be invoked only when the	1168	<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	1169	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>	1170	during the same loop iteration then order of execution is undefined.</p>
		1171
		1172	</div>
		1173	<h3 id="Watcher_Specific_Functions_and_Data_-3">Watcher-Specific Functions and Data Members</h3>
		1174	<div id="Watcher_Specific_Functions_and_Data_-2">
888	<dl>	1175	<dl>
889	<dt>ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)</dt>	1176	<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>	1177	<dt>ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)</dt>
891	<dd>	1178	<dd>
892	<p>Lots of arguments, lets sort it out... There are basically three modes of	1179	<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>	1180	operation, and we will explain them from simplest to complex:</p>
894	<p>	1181	<p>
895	<dl>	1182	<dl>
896	<dt>* absolute timer (interval = reschedule_cb = 0)</dt>	1183	<dt>* absolute timer (at = time, interval = reschedule_cb = 0)</dt>
897	<dd>	1184	<dd>
898	<p>In this configuration the watcher triggers an event at the wallclock time	1185	<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,	1186	<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	1187	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>	1188	system time reaches or surpasses this time.</p>
902	</dd>	1189	</dd>
903	<dt>* non-repeating interval timer (interval > 0, reschedule_cb = 0)</dt>	1190	<dt>* non-repeating interval timer (at = offset, interval > 0, reschedule_cb = 0)</dt>
904	<dd>	1191	<dd>
905	<p>In this mode the watcher will always be scheduled to time out at the next	1192	<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	1193	<code>at + N * interval</code> time (for some integer N, which can also be negative)
907	of any time jumps.</p>	1194	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	1195	<p>This can be used to create timers that do not drift with respect to system
909	time:</p>	1196	time:</p>
910	<pre> ev_periodic_set (&periodic, 0., 3600., 0);	1197	<pre> ev_periodic_set (&periodic, 0., 3600., 0);
911		1198
912	</pre>	1199	</pre>
…		…
915	full hour (UTC), or more correctly, when the system time is evenly divisible	1202	full hour (UTC), or more correctly, when the system time is evenly divisible
916	by 3600.</p>	1203	by 3600.</p>
917	<p>Another way to think about it (for the mathematically inclined) is that	1204	<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	1205	<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>	1206	time where <code>time = at (mod interval)</code>, regardless of any time jumps.</p>
		1207	<p>For numerical stability it is preferable that the <code>at</code> value is near
		1208	<code>ev_now ()</code> (the current time), but there is no range requirement for
		1209	this value.</p>
920	</dd>	1210	</dd>
921	<dt>* manual reschedule mode (reschedule_cb = callback)</dt>	1211	<dt>* manual reschedule mode (at and interval ignored, reschedule_cb = callback)</dt>
922	<dd>	1212	<dd>
923	<p>In this mode the values for <code>interval</code> and <code>at</code> are both being	1213	<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	1214	ignored. Instead, each time the periodic watcher gets scheduled, the
925	reschedule callback will be called with the watcher as first, and the	1215	reschedule callback will be called with the watcher as first, and the
926	current time as second argument.</p>	1216	current time as second argument.</p>
927	<p>NOTE: <i>This callback MUST NOT stop or destroy any periodic watcher,	1217	<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,	1218	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	1219	return <code>now + 1e30</code> (or so, fudge fudge) and stop it afterwards (e.g. by
930	starting a prepare watcher).</p>	1220	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,	1221	<p>Its prototype is <code>ev_tstamp (reschedule_cb)(struct ev_periodic w,
932	ev_tstamp now)</code>, e.g.:</p>	1222	ev_tstamp now)</code>, e.g.:</p>
933	<pre> static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now)	1223	<pre> static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now)
934	{	1224	{
935	return now + 60.;	1225	return now + 60.;
…		…
956	<p>Simply stops and restarts the periodic watcher again. This is only useful	1246	<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	1247	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	1248	a different time than the last time it was called (e.g. in a crond like
959	program when the crontabs have changed).</p>	1249	program when the crontabs have changed).</p>
960	</dd>	1250	</dd>
		1251	<dt>ev_tstamp offset [read-write]</dt>
		1252	<dd>
		1253	<p>When repeating, this contains the offset value, otherwise this is the
		1254	absolute point in time (the <code>at</code> value passed to <code>ev_periodic_set</code>).</p>
		1255	<p>Can be modified any time, but changes only take effect when the periodic
		1256	timer fires or <code>ev_periodic_again</code> is being called.</p>
		1257	</dd>
		1258	<dt>ev_tstamp interval [read-write]</dt>
		1259	<dd>
		1260	<p>The current interval value. Can be modified any time, but changes only
		1261	take effect when the periodic timer fires or <code>ev_periodic_again</code> is being
		1262	called.</p>
		1263	</dd>
		1264	<dt>ev_tstamp (reschedule_cb)(struct ev_periodic w, ev_tstamp now) [read-write]</dt>
		1265	<dd>
		1266	<p>The current reschedule callback, or <code>0</code>, if this functionality is
		1267	switched off. Can be changed any time, but changes only take effect when
		1268	the periodic timer fires or <code>ev_periodic_again</code> is being called.</p>
		1269	</dd>
961	</dl>	1270	</dl>
962	<p>Example: call a callback every hour, or, more precisely, whenever the	1271	<p>Example: Call a callback every hour, or, more precisely, whenever the
963	system clock is divisible by 3600. The callback invocation times have	1272	system clock is divisible by 3600. The callback invocation times have
964	potentially a lot of jittering, but good long-term stability.</p>	1273	potentially a lot of jittering, but good long-term stability.</p>
965	<pre> static void	1274	<pre> static void
966	clock_cb (struct ev_loop loop, struct ev_io w, int revents)	1275	clock_cb (struct ev_loop loop, struct ev_io w, int revents)
967	{	1276	{
…		…
971	struct ev_periodic hourly_tick;	1280	struct ev_periodic hourly_tick;
972	ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);	1281	ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);
973	ev_periodic_start (loop, &hourly_tick);	1282	ev_periodic_start (loop, &hourly_tick);
974		1283
975	</pre>	1284	</pre>
976	<p>Example: the same as above, but use a reschedule callback to do it:</p>	1285	<p>Example: The same as above, but use a reschedule callback to do it:</p>
977	<pre> #include <math.h>	1286	<pre> #include <math.h>
978		1287
979	static ev_tstamp	1288	static ev_tstamp
980	my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)	1289	my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)
981	{	1290	{
…		…
983	}	1292	}
984		1293
985	ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);	1294	ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);
986		1295
987	</pre>	1296	</pre>
988	<p>Example: call a callback every hour, starting now:</p>	1297	<p>Example: Call a callback every hour, starting now:</p>
989	<pre> struct ev_periodic hourly_tick;	1298	<pre> struct ev_periodic hourly_tick;
990	ev_periodic_init (&hourly_tick, clock_cb,	1299	ev_periodic_init (&hourly_tick, clock_cb,
991	fmod (ev_now (loop), 3600.), 3600., 0);	1300	fmod (ev_now (loop), 3600.), 3600., 0);
992	ev_periodic_start (loop, &hourly_tick);	1301	ev_periodic_start (loop, &hourly_tick);
993		1302
…		…
995		1304
996		1305
997	</pre>	1306	</pre>
998		1307
999	</div>	1308	</div>
1000	<h2 id="code_ev_signal_code_signal_me_when_a"><code>ev_signal</code> - signal me when a signal gets signalled</h2>	1309	<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">	1310	<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	1311	<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	1312	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	1313	will try it's best to deliver signals synchronously, i.e. as part of the
1005	normal event processing, like any other event.</p>	1314	normal event processing, like any other event.</p>
…		…
1007	first watcher gets started will libev actually register a signal watcher	1316	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	1317	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	1318	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	1319	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>	1320	SIG_DFL (regardless of what it was set to before).</p>
		1321
		1322	</div>
		1323	<h3 id="Watcher_Specific_Functions_and_Data_-4">Watcher-Specific Functions and Data Members</h3>
		1324	<div id="Watcher_Specific_Functions_and_Data_-2-2">
1012	<dl>	1325	<dl>
1013	<dt>ev_signal_init (ev_signal *, callback, int signum)</dt>	1326	<dt>ev_signal_init (ev_signal *, callback, int signum)</dt>
1014	<dt>ev_signal_set (ev_signal *, int signum)</dt>	1327	<dt>ev_signal_set (ev_signal *, int signum)</dt>
1015	<dd>	1328	<dd>
1016	<p>Configures the watcher to trigger on the given signal number (usually one	1329	<p>Configures the watcher to trigger on the given signal number (usually one
1017	of the <code>SIGxxx</code> constants).</p>	1330	of the <code>SIGxxx</code> constants).</p>
1018	</dd>	1331	</dd>
		1332	<dt>int signum [read-only]</dt>
		1333	<dd>
		1334	<p>The signal the watcher watches out for.</p>
		1335	</dd>
1019	</dl>	1336	</dl>
1020		1337
1021		1338
1022		1339
1023		1340
1024		1341
1025	</div>	1342	</div>
1026	<h2 id="code_ev_child_code_wait_for_pid_stat"><code>ev_child</code> - wait for pid status changes</h2>	1343	<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">	1344	<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	1345	<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>	1346	some child status changes (most typically when a child of yours dies).</p>
		1347
		1348	</div>
		1349	<h3 id="Watcher_Specific_Functions_and_Data_-5">Watcher-Specific Functions and Data Members</h3>
		1350	<div id="Watcher_Specific_Functions_and_Data_-2-3">
1030	<dl>	1351	<dl>
1031	<dt>ev_child_init (ev_child *, callback, int pid)</dt>	1352	<dt>ev_child_init (ev_child *, callback, int pid)</dt>
1032	<dt>ev_child_set (ev_child *, int pid)</dt>	1353	<dt>ev_child_set (ev_child *, int pid)</dt>
1033	<dd>	1354	<dd>
1034	<p>Configures the watcher to wait for status changes of process <code>pid</code> (or	1355	<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	1357	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	1358	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	1359	<code>waitpid</code> documentation). The <code>rpid</code> member contains the pid of the
1039	process causing the status change.</p>	1360	process causing the status change.</p>
1040	</dd>	1361	</dd>
		1362	<dt>int pid [read-only]</dt>
		1363	<dd>
		1364	<p>The process id this watcher watches out for, or <code>0</code>, meaning any process id.</p>
		1365	</dd>
		1366	<dt>int rpid [read-write]</dt>
		1367	<dd>
		1368	<p>The process id that detected a status change.</p>
		1369	</dd>
		1370	<dt>int rstatus [read-write]</dt>
		1371	<dd>
		1372	<p>The process exit/trace status caused by <code>rpid</code> (see your systems
		1373	<code>waitpid</code> and <code>sys/wait.h</code> documentation for details).</p>
		1374	</dd>
1041	</dl>	1375	</dl>
1042	<p>Example: try to exit cleanly on SIGINT and SIGTERM.</p>	1376	<p>Example: Try to exit cleanly on SIGINT and SIGTERM.</p>
1043	<pre> static void	1377	<pre> static void
1044	sigint_cb (struct ev_loop loop, struct ev_signal w, int revents)	1378	sigint_cb (struct ev_loop loop, struct ev_signal w, int revents)
1045	{	1379	{
1046	ev_unloop (loop, EVUNLOOP_ALL);	1380	ev_unloop (loop, EVUNLOOP_ALL);
1047	}	1381	}
…		…
1054		1388
1055		1389
1056	</pre>	1390	</pre>
1057		1391
1058	</div>	1392	</div>
		1393	<h2 id="code_ev_stat_code_did_the_file_attri"><code>ev_stat</code> - did the file attributes just change?</h2>
		1394	<div id="code_ev_stat_code_did_the_file_attri-2">
		1395	<p>This watches a filesystem path for attribute changes. That is, it calls
		1396	<code>stat</code> regularly (or when the OS says it changed) and sees if it changed
		1397	compared to the last time, invoking the callback if it did.</p>
		1398	<p>The path does not need to exist: changing from "path exists" to "path does
		1399	not exist" is a status change like any other. The condition "path does
		1400	not exist" is signified by the <code>st_nlink</code> field being zero (which is
		1401	otherwise always forced to be at least one) and all the other fields of
		1402	the stat buffer having unspecified contents.</p>
		1403	<p>The path <i>should</i> be absolute and <i>must not</i> end in a slash. If it is
		1404	relative and your working directory changes, the behaviour is undefined.</p>
		1405	<p>Since there is no standard to do this, the portable implementation simply
		1406	calls <code>stat (2)</code> regularly on the path to see if it changed somehow. You
		1407	can specify a recommended polling interval for this case. If you specify
		1408	a polling interval of <code>0</code> (highly recommended!) then a <i>suitable,
		1409	unspecified default</i> value will be used (which you can expect to be around
		1410	five seconds, although this might change dynamically). Libev will also
		1411	impose a minimum interval which is currently around <code>0.1</code>, but thats
		1412	usually overkill.</p>
		1413	<p>This watcher type is not meant for massive numbers of stat watchers,
		1414	as even with OS-supported change notifications, this can be
		1415	resource-intensive.</p>
		1416	<p>At the time of this writing, only the Linux inotify interface is
		1417	implemented (implementing kqueue support is left as an exercise for the
		1418	reader). Inotify will be used to give hints only and should not change the
		1419	semantics of <code>ev_stat</code> watchers, which means that libev sometimes needs
		1420	to fall back to regular polling again even with inotify, but changes are
		1421	usually detected immediately, and if the file exists there will be no
		1422	polling.</p>
		1423
		1424	</div>
		1425	<h3 id="Watcher_Specific_Functions_and_Data_-6">Watcher-Specific Functions and Data Members</h3>
		1426	<div id="Watcher_Specific_Functions_and_Data_-2-4">
		1427	<dl>
		1428	<dt>ev_stat_init (ev_stat , callback, const char path, ev_tstamp interval)</dt>
		1429	<dt>ev_stat_set (ev_stat , const char path, ev_tstamp interval)</dt>
		1430	<dd>
		1431	<p>Configures the watcher to wait for status changes of the given
		1432	<code>path</code>. The <code>interval</code> is a hint on how quickly a change is expected to
		1433	be detected and should normally be specified as <code>0</code> to let libev choose
		1434	a suitable value. The memory pointed to by <code>path</code> must point to the same
		1435	path for as long as the watcher is active.</p>
		1436	<p>The callback will be receive <code>EV_STAT</code> when a change was detected,
		1437	relative to the attributes at the time the watcher was started (or the
		1438	last change was detected).</p>
		1439	</dd>
		1440	<dt>ev_stat_stat (ev_stat *)</dt>
		1441	<dd>
		1442	<p>Updates the stat buffer immediately with new values. If you change the
		1443	watched path in your callback, you could call this fucntion to avoid
		1444	detecting this change (while introducing a race condition). Can also be
		1445	useful simply to find out the new values.</p>
		1446	</dd>
		1447	<dt>ev_statdata attr [read-only]</dt>
		1448	<dd>
		1449	<p>The most-recently detected attributes of the file. Although the type is of
		1450	<code>ev_statdata</code>, this is usually the (or one of the) <code>struct stat</code> types
		1451	suitable for your system. If the <code>st_nlink</code> member is <code>0</code>, then there
		1452	was some error while <code>stat</code>ing the file.</p>
		1453	</dd>
		1454	<dt>ev_statdata prev [read-only]</dt>
		1455	<dd>
		1456	<p>The previous attributes of the file. The callback gets invoked whenever
		1457	<code>prev</code> != <code>attr</code>.</p>
		1458	</dd>
		1459	<dt>ev_tstamp interval [read-only]</dt>
		1460	<dd>
		1461	<p>The specified interval.</p>
		1462	</dd>
		1463	<dt>const char *path [read-only]</dt>
		1464	<dd>
		1465	<p>The filesystem path that is being watched.</p>
		1466	</dd>
		1467	</dl>
		1468	<p>Example: Watch <code>/etc/passwd</code> for attribute changes.</p>
		1469	<pre> static void
		1470	passwd_cb (struct ev_loop loop, ev_stat w, int revents)
		1471	{
		1472	/* /etc/passwd changed in some way */
		1473	if (w->attr.st_nlink)
		1474	{
		1475	printf ("passwd current size %ld\n", (long)w->attr.st_size);
		1476	printf ("passwd current atime %ld\n", (long)w->attr.st_mtime);
		1477	printf ("passwd current mtime %ld\n", (long)w->attr.st_mtime);
		1478	}
		1479	else
		1480	/* you shalt not abuse printf for puts */
		1481	puts ("wow, /etc/passwd is not there, expect problems. "
		1482	"if this is windows, they already arrived\n");
		1483	}
		1484
		1485	...
		1486	ev_stat passwd;
		1487
		1488	ev_stat_init (&passwd, passwd_cb, "/etc/passwd");
		1489	ev_stat_start (loop, &passwd);
		1490
		1491
		1492
		1493
		1494	</pre>
		1495
		1496	</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>	1497	<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">	1498	<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	1499	<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	1500	priority are pending (prepare, check and other idle watchers do not
1063	as your process is busy handling sockets or timeouts (or even signals,	1501	count).</p>
1064	imagine) it will not be triggered. But when your process is idle all idle	1502	<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 -	1503	(or even signals, imagine) of the same or higher priority it will not be
		1504	triggered. But when your process is idle (or only lower-priority watchers
		1505	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	1506	iteration - until stopped, that is, or your process receives more events
1067	busy.</p>	1507	and becomes busy again with higher priority stuff.</p>
1068	<p>The most noteworthy effect is that as long as any idle watchers are	1508	<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>	1509	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	1510	<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	1511	effect on its own sometimes), idle watchers are a good place to do
1072	"pseudo-background processing", or delay processing stuff to after the	1512	"pseudo-background processing", or delay processing stuff to after the
1073	event loop has handled all outstanding events.</p>	1513	event loop has handled all outstanding events.</p>
		1514
		1515	</div>
		1516	<h3 id="Watcher_Specific_Functions_and_Data_-7">Watcher-Specific Functions and Data Members</h3>
		1517	<div id="Watcher_Specific_Functions_and_Data_-2-5">
1074	<dl>	1518	<dl>
1075	<dt>ev_idle_init (ev_signal *, callback)</dt>	1519	<dt>ev_idle_init (ev_signal *, callback)</dt>
1076	<dd>	1520	<dd>
1077	<p>Initialises and configures the idle watcher - it has no parameters of any	1521	<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,	1522	kind. There is a <code>ev_idle_set</code> macro, but using it is utterly pointless,
1079	believe me.</p>	1523	believe me.</p>
1080	</dd>	1524	</dd>
1081	</dl>	1525	</dl>
1082	<p>Example: dynamically allocate an <code>ev_idle</code>, start it, and in the	1526	<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>	1527	callback, free it. Also, use no error checking, as usual.</p>
1084	<pre> static void	1528	<pre> static void
1085	idle_cb (struct ev_loop loop, struct ev_idle w, int revents)	1529	idle_cb (struct ev_loop loop, struct ev_idle w, int revents)
1086	{	1530	{
1087	free (w);	1531	free (w);
1088	// now do something you wanted to do when the program has	1532	// now do something you wanted to do when the program has
…		…
1097		1541
1098		1542
1099	</pre>	1543	</pre>
1100		1544
1101	</div>	1545	</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>	1546	<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">	1547	<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:	1548	<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	1549	prepare watchers get invoked before the process blocks and check watchers
1106	afterwards.</p>	1550	afterwards.</p>
		1551	<p>You <i>must not</i> call <code>ev_loop</code> or similar functions that enter
		1552	the current event loop from either <code>ev_prepare</code> or <code>ev_check</code>
		1553	watchers. Other loops than the current one are fine, however. The
		1554	rationale behind this is that you do not need to check for recursion in
		1555	those watchers, i.e. the sequence will always be <code>ev_prepare</code>, blocking,
		1556	<code>ev_check</code> so if you have one watcher of each kind they will always be
		1557	called in pairs bracketing the blocking call.</p>
1107	<p>Their main purpose is to integrate other event mechanisms into libev and	1558	<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	1559	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	1560	variable changes, implement your own watchers, integrate net-snmp or a
1110	coroutine library and lots more.</p>	1561	coroutine library and lots more. They are also occasionally useful if
		1562	you cache some data and want to flush it before blocking (for example,
		1563	in X programs you might want to do an <code>XFlush ()</code> in an <code>ev_prepare</code>
		1564	watcher).</p>
1111	<p>This is done by examining in each prepare call which file descriptors need	1565	<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	1566	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	1567	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	1568	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	1569	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	1576	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	1577	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	1578	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	1579	loop from blocking if lower-priority coroutines are active, thus mapping
1126	low-priority coroutines to idle/background tasks).</p>	1580	low-priority coroutines to idle/background tasks).</p>
		1581	<p>It is recommended to give <code>ev_check</code> watchers highest (<code>EV_MAXPRI</code>)
		1582	priority, to ensure that they are being run before any other watchers
		1583	after the poll. Also, <code>ev_check</code> watchers (and <code>ev_prepare</code> watchers,
		1584	too) should not activate ("feed") events into libev. While libev fully
		1585	supports this, they will be called before other <code>ev_check</code> watchers did
		1586	their job. As <code>ev_check</code> watchers are often used to embed other event
		1587	loops those other event loops might be in an unusable state until their
		1588	<code>ev_check</code> watcher ran (always remind yourself to coexist peacefully with
		1589	others).</p>
		1590
		1591	</div>
		1592	<h3 id="Watcher_Specific_Functions_and_Data_-8">Watcher-Specific Functions and Data Members</h3>
		1593	<div id="Watcher_Specific_Functions_and_Data_-2-6">
1127	<dl>	1594	<dl>
1128	<dt>ev_prepare_init (ev_prepare *, callback)</dt>	1595	<dt>ev_prepare_init (ev_prepare *, callback)</dt>
1129	<dt>ev_check_init (ev_check *, callback)</dt>	1596	<dt>ev_check_init (ev_check *, callback)</dt>
1130	<dd>	1597	<dd>
1131	<p>Initialises and configures the prepare or check watcher - they have no	1598	<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>	1599	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>	1600	macros, but using them is utterly, utterly and completely pointless.</p>
1134	</dd>	1601	</dd>
1135	</dl>	1602	</dl>
1136	<p>Example: TODO.</p>	1603	<p>There are a number of principal ways to embed other event loops or modules
		1604	into libev. Here are some ideas on how to include libadns into libev
		1605	(there is a Perl module named <code>EV::ADNS</code> that does this, which you could
		1606	use for an actually working example. Another Perl module named <code>EV::Glib</code>
		1607	embeds a Glib main context into libev, and finally, <code>Glib::EV</code> embeds EV
		1608	into the Glib event loop).</p>
		1609	<p>Method 1: Add IO watchers and a timeout watcher in a prepare handler,
		1610	and in a check watcher, destroy them and call into libadns. What follows
		1611	is pseudo-code only of course. This requires you to either use a low
		1612	priority for the check watcher or use <code>ev_clear_pending</code> explicitly, as
		1613	the callbacks for the IO/timeout watchers might not have been called yet.</p>
		1614	<pre> static ev_io iow [nfd];
		1615	static ev_timer tw;
1137		1616
		1617	static void
		1618	io_cb (ev_loop loop, ev_io w, int revents)
		1619	{
		1620	}
1138		1621
		1622	// create io watchers for each fd and a timer before blocking
		1623	static void
		1624	adns_prepare_cb (ev_loop loop, ev_prepare w, int revents)
		1625	{
		1626	int timeout = 3600000;
		1627	struct pollfd fds [nfd];
		1628	// actual code will need to loop here and realloc etc.
		1629	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));
1139		1630
		1631	/* the callback is illegal, but won't be called as we stop during check */
		1632	ev_timer_init (&tw, 0, timeout * 1e-3);
		1633	ev_timer_start (loop, &tw);
1140		1634
		1635	// create one ev_io per pollfd
		1636	for (int i = 0; i < nfd; ++i)
		1637	{
		1638	ev_io_init (iow + i, io_cb, fds [i].fd,
		1639	((fds [i].events & POLLIN ? EV_READ : 0)
		1640	\| (fds [i].events & POLLOUT ? EV_WRITE : 0)));
1141		1641
		1642	fds [i].revents = 0;
		1643	ev_io_start (loop, iow + i);
		1644	}
		1645	}
		1646
		1647	// stop all watchers after blocking
		1648	static void
		1649	adns_check_cb (ev_loop loop, ev_check w, int revents)
		1650	{
		1651	ev_timer_stop (loop, &tw);
		1652
		1653	for (int i = 0; i < nfd; ++i)
		1654	{
		1655	// set the relevant poll flags
		1656	// could also call adns_processreadable etc. here
		1657	struct pollfd *fd = fds + i;
		1658	int revents = ev_clear_pending (iow + i);
		1659	if (revents & EV_READ ) fd->revents \|= fd->events & POLLIN;
		1660	if (revents & EV_WRITE) fd->revents \|= fd->events & POLLOUT;
		1661
		1662	// now stop the watcher
		1663	ev_io_stop (loop, iow + i);
		1664	}
		1665
		1666	adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));
		1667	}
		1668
		1669	</pre>
		1670	<p>Method 2: This would be just like method 1, but you run <code>adns_afterpoll</code>
		1671	in the prepare watcher and would dispose of the check watcher.</p>
		1672	<p>Method 3: If the module to be embedded supports explicit event
		1673	notification (adns does), you can also make use of the actual watcher
		1674	callbacks, and only destroy/create the watchers in the prepare watcher.</p>
		1675	<pre> static void
		1676	timer_cb (EV_P_ ev_timer *w, int revents)
		1677	{
		1678	adns_state ads = (adns_state)w->data;
		1679	update_now (EV_A);
		1680
		1681	adns_processtimeouts (ads, &tv_now);
		1682	}
		1683
		1684	static void
		1685	io_cb (EV_P_ ev_io *w, int revents)
		1686	{
		1687	adns_state ads = (adns_state)w->data;
		1688	update_now (EV_A);
		1689
		1690	if (revents & EV_READ ) adns_processreadable (ads, w->fd, &tv_now);
		1691	if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now);
		1692	}
		1693
		1694	// do not ever call adns_afterpoll
		1695
		1696	</pre>
		1697	<p>Method 4: Do not use a prepare or check watcher because the module you
		1698	want to embed is too inflexible to support it. Instead, youc na override
		1699	their poll function. The drawback with this solution is that the main
		1700	loop is now no longer controllable by EV. The <code>Glib::EV</code> module does
		1701	this.</p>
		1702	<pre> static gint
		1703	event_poll_func (GPollFD *fds, guint nfds, gint timeout)
		1704	{
		1705	int got_events = 0;
		1706
		1707	for (n = 0; n < nfds; ++n)
		1708	// create/start io watcher that sets the relevant bits in fds[n] and increment got_events
		1709
		1710	if (timeout >= 0)
		1711	// create/start timer
		1712
		1713	// poll
		1714	ev_loop (EV_A_ 0);
		1715
		1716	// stop timer again
		1717	if (timeout >= 0)
		1718	ev_timer_stop (EV_A_ &to);
		1719
		1720	// stop io watchers again - their callbacks should have set
		1721	for (n = 0; n < nfds; ++n)
		1722	ev_io_stop (EV_A_ iow [n]);
		1723
		1724	return got_events;
		1725	}
		1726
		1727
		1728
		1729
		1730	</pre>
		1731
1142	</div>	1732	</div>
1143	<h2 id="code_ev_embed_code_when_one_backend_"><code>ev_embed</code> - when one backend isn't enough</h2>	1733	<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">	1734	<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	1735	<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	1736	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	1737	loop, other types of watchers might be handled in a delayed or incorrect
1148	fashion and must not be used).</p>	1738	fashion and must not be used).</p>
…		…
1200	}	1790	}
1201	else	1791	else
1202	loop_lo = loop_hi;	1792	loop_lo = loop_hi;
1203		1793
1204	</pre>	1794	</pre>
		1795
		1796	</div>
		1797	<h3 id="Watcher_Specific_Functions_and_Data_-9">Watcher-Specific Functions and Data Members</h3>
		1798	<div id="Watcher_Specific_Functions_and_Data_-2-7">
1205	<dl>	1799	<dl>
1206	<dt>ev_embed_init (ev_embed , callback, struct ev_loop embedded_loop)</dt>	1800	<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>	1801	<dt>ev_embed_set (ev_embed , callback, struct ev_loop embedded_loop)</dt>
1208	<dd>	1802	<dd>
1209	<p>Configures the watcher to embed the given loop, which must be	1803	<p>Configures the watcher to embed the given loop, which must be
…		…
1216	<dd>	1810	<dd>
1217	<p>Make a single, non-blocking sweep over the embedded loop. This works	1811	<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	1812	similarly to <code>ev_loop (embedded_loop, EVLOOP_NONBLOCK)</code>, but in the most
1219	apropriate way for embedded loops.</p>	1813	apropriate way for embedded loops.</p>
1220	</dd>	1814	</dd>
		1815	<dt>struct ev_loop *loop [read-only]</dt>
		1816	<dd>
		1817	<p>The embedded event loop.</p>
		1818	</dd>
1221	</dl>	1819	</dl>
1222		1820
1223		1821
1224		1822
1225		1823
1226		1824
1227	</div>	1825	</div>
1228	<h1 id="OTHER_FUNCTIONS">OTHER FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p>	1826	<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>
		1827	<div id="code_ev_fork_code_the_audacity_to_re-2">
		1828	<p>Fork watchers are called when a <code>fork ()</code> was detected (usually because
		1829	whoever is a good citizen cared to tell libev about it by calling
		1830	<code>ev_default_fork</code> or <code>ev_loop_fork</code>). The invocation is done before the
		1831	event loop blocks next and before <code>ev_check</code> watchers are being called,
		1832	and only in the child after the fork. If whoever good citizen calling
		1833	<code>ev_default_fork</code> cheats and calls it in the wrong process, the fork
		1834	handlers will be invoked, too, of course.</p>
		1835	<dl>
		1836	<dt>ev_fork_init (ev_signal *, callback)</dt>
		1837	<dd>
		1838	<p>Initialises and configures the fork watcher - it has no parameters of any
		1839	kind. There is a <code>ev_fork_set</code> macro, but using it is utterly pointless,
		1840	believe me.</p>
		1841	</dd>
		1842	</dl>
		1843
		1844
		1845
		1846
		1847
		1848	</div>
		1849	<h1 id="OTHER_FUNCTIONS">OTHER FUNCTIONS</h1>
1229	<div id="OTHER_FUNCTIONS_CONTENT">	1850	<div id="OTHER_FUNCTIONS_CONTENT">
1230	<p>There are some other functions of possible interest. Described. Here. Now.</p>	1851	<p>There are some other functions of possible interest. Described. Here. Now.</p>
1231	<dl>	1852	<dl>
1232	<dt>ev_once (loop, int fd, int events, ev_tstamp timeout, callback)</dt>	1853	<dt>ev_once (loop, int fd, int events, ev_tstamp timeout, callback)</dt>
1233	<dd>	1854	<dd>
…		…
1280		1901
1281		1902
1282		1903
1283		1904
1284	</div>	1905	</div>
1285	<h1 id="LIBEVENT_EMULATION">LIBEVENT EMULATION</h1><p><a href="#TOP" class="toplink">Top</a></p>	1906	<h1 id="LIBEVENT_EMULATION">LIBEVENT EMULATION</h1>
1286	<div id="LIBEVENT_EMULATION_CONTENT">	1907	<div id="LIBEVENT_EMULATION_CONTENT">
1287	<p>Libev offers a compatibility emulation layer for libevent. It cannot	1908	<p>Libev offers a compatibility emulation layer for libevent. It cannot
1288	emulate the internals of libevent, so here are some usage hints:</p>	1909	emulate the internals of libevent, so here are some usage hints:</p>
1289	<dl>	1910	<dl>
1290	<dt>* Use it by including <event.h>, as usual.</dt>	1911	<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	1921	<dt>* The libev emulation is <i>not</i> ABI compatible to libevent, you need
1301	to use the libev header file and library.</dt>	1922	to use the libev header file and library.</dt>
1302	</dl>	1923	</dl>
1303		1924
1304	</div>	1925	</div>
1305	<h1 id="C_SUPPORT">C++ SUPPORT</h1><p><a href="#TOP" class="toplink">Top</a></p>	1926	<h1 id="C_SUPPORT">C++ SUPPORT</h1>
1306	<div id="C_SUPPORT_CONTENT">	1927	<div id="C_SUPPORT_CONTENT">
1307	<p>TBD.</p>	1928	<p>Libev comes with some simplistic wrapper classes for C++ that mainly allow
		1929	you to use some convinience methods to start/stop watchers and also change
		1930	the callback model to a model using method callbacks on objects.</p>
		1931	<p>To use it,</p>
		1932	<pre> #include <ev++.h>
1308		1933
		1934	</pre>
		1935	<p>This automatically includes <cite>ev.h</cite> and puts all of its definitions (many
		1936	of them macros) into the global namespace. All C++ specific things are
		1937	put into the <code>ev</code> namespace. It should support all the same embedding
		1938	options as <cite>ev.h</cite>, most notably <code>EV_MULTIPLICITY</code>.</p>
		1939	<p>Care has been taken to keep the overhead low. The only data member the C++
		1940	classes add (compared to plain C-style watchers) is the event loop pointer
		1941	that the watcher is associated with (or no additional members at all if
		1942	you disable <code>EV_MULTIPLICITY</code> when embedding libev).</p>
		1943	<p>Currently, functions, and static and non-static member functions can be
		1944	used as callbacks. Other types should be easy to add as long as they only
		1945	need one additional pointer for context. If you need support for other
		1946	types of functors please contact the author (preferably after implementing
		1947	it).</p>
		1948	<p>Here is a list of things available in the <code>ev</code> namespace:</p>
		1949	<dl>
		1950	<dt><code>ev::READ</code>, <code>ev::WRITE</code> etc.</dt>
		1951	<dd>
		1952	<p>These are just enum values with the same values as the <code>EV_READ</code> etc.
		1953	macros from <cite>ev.h</cite>.</p>
		1954	</dd>
		1955	<dt><code>ev::tstamp</code>, <code>ev::now</code></dt>
		1956	<dd>
		1957	<p>Aliases to the same types/functions as with the <code>ev_</code> prefix.</p>
		1958	</dd>
		1959	<dt><code>ev::io</code>, <code>ev::timer</code>, <code>ev::periodic</code>, <code>ev::idle</code>, <code>ev::sig</code> etc.</dt>
		1960	<dd>
		1961	<p>For each <code>ev_TYPE</code> watcher in <cite>ev.h</cite> there is a corresponding class of
		1962	the same name in the <code>ev</code> namespace, with the exception of <code>ev_signal</code>
		1963	which is called <code>ev::sig</code> to avoid clashes with the <code>signal</code> macro
		1964	defines by many implementations.</p>
		1965	<p>All of those classes have these methods:</p>
		1966	<p>
		1967	<dl>
		1968	<dt>ev::TYPE::TYPE ()</dt>
		1969	<dt>ev::TYPE::TYPE (struct ev_loop *)</dt>
		1970	<dt>ev::TYPE::~TYPE</dt>
		1971	<dd>
		1972	<p>The constructor (optionally) takes an event loop to associate the watcher
		1973	with. If it is omitted, it will use <code>EV_DEFAULT</code>.</p>
		1974	<p>The constructor calls <code>ev_init</code> for you, which means you have to call the
		1975	<code>set</code> method before starting it.</p>
		1976	<p>It will not set a callback, however: You have to call the templated <code>set</code>
		1977	method to set a callback before you can start the watcher.</p>
		1978	<p>(The reason why you have to use a method is a limitation in C++ which does
		1979	not allow explicit template arguments for constructors).</p>
		1980	<p>The destructor automatically stops the watcher if it is active.</p>
		1981	</dd>
		1982	<dt>w->set<class, &class::method> (object *)</dt>
		1983	<dd>
		1984	<p>This method sets the callback method to call. The method has to have a
		1985	signature of <code>void (*)(ev_TYPE &, int)</code>, it receives the watcher as
		1986	first argument and the <code>revents</code> as second. The object must be given as
		1987	parameter and is stored in the <code>data</code> member of the watcher.</p>
		1988	<p>This method synthesizes efficient thunking code to call your method from
		1989	the C callback that libev requires. If your compiler can inline your
		1990	callback (i.e. it is visible to it at the place of the <code>set</code> call and
		1991	your compiler is good :), then the method will be fully inlined into the
		1992	thunking function, making it as fast as a direct C callback.</p>
		1993	<p>Example: simple class declaration and watcher initialisation</p>
		1994	<pre> struct myclass
		1995	{
		1996	void io_cb (ev::io &w, int revents) { }
		1997	}
		1998
		1999	myclass obj;
		2000	ev::io iow;
		2001	iow.set <myclass, &myclass::io_cb> (&obj);
		2002
		2003	</pre>
		2004	</dd>
		2005	<dt>w->set<function> (void *data = 0)</dt>
		2006	<dd>
		2007	<p>Also sets a callback, but uses a static method or plain function as
		2008	callback. The optional <code>data</code> argument will be stored in the watcher's
		2009	<code>data</code> member and is free for you to use.</p>
		2010	<p>The prototype of the <code>function</code> must be <code>void (*)(ev::TYPE &w, int)</code>.</p>
		2011	<p>See the method-<code>set</code> above for more details.</p>
		2012	<p>Example:</p>
		2013	<pre> static void io_cb (ev::io &w, int revents) { }
		2014	iow.set <io_cb> ();
		2015
		2016	</pre>
		2017	</dd>
		2018	<dt>w->set (struct ev_loop *)</dt>
		2019	<dd>
		2020	<p>Associates a different <code>struct ev_loop</code> with this watcher. You can only
		2021	do this when the watcher is inactive (and not pending either).</p>
		2022	</dd>
		2023	<dt>w->set ([args])</dt>
		2024	<dd>
		2025	<p>Basically the same as <code>ev_TYPE_set</code>, with the same args. Must be
		2026	called at least once. Unlike the C counterpart, an active watcher gets
		2027	automatically stopped and restarted when reconfiguring it with this
		2028	method.</p>
		2029	</dd>
		2030	<dt>w->start ()</dt>
		2031	<dd>
		2032	<p>Starts the watcher. Note that there is no <code>loop</code> argument, as the
		2033	constructor already stores the event loop.</p>
		2034	</dd>
		2035	<dt>w->stop ()</dt>
		2036	<dd>
		2037	<p>Stops the watcher if it is active. Again, no <code>loop</code> argument.</p>
		2038	</dd>
		2039	<dt>w->again () <code>ev::timer</code>, <code>ev::periodic</code> only</dt>
		2040	<dd>
		2041	<p>For <code>ev::timer</code> and <code>ev::periodic</code>, this invokes the corresponding
		2042	<code>ev_TYPE_again</code> function.</p>
		2043	</dd>
		2044	<dt>w->sweep () <code>ev::embed</code> only</dt>
		2045	<dd>
		2046	<p>Invokes <code>ev_embed_sweep</code>.</p>
		2047	</dd>
		2048	<dt>w->update () <code>ev::stat</code> only</dt>
		2049	<dd>
		2050	<p>Invokes <code>ev_stat_stat</code>.</p>
		2051	</dd>
		2052	</dl>
		2053	</p>
		2054	</dd>
		2055	</dl>
		2056	<p>Example: Define a class with an IO and idle watcher, start one of them in
		2057	the constructor.</p>
		2058	<pre> class myclass
		2059	{
		2060	ev_io io; void io_cb (ev::io &w, int revents);
		2061	ev_idle idle void idle_cb (ev::idle &w, int revents);
		2062
		2063	myclass ();
		2064	}
		2065
		2066	myclass::myclass (int fd)
		2067	{
		2068	io .set <myclass, &myclass::io_cb > (this);
		2069	idle.set <myclass, &myclass::idle_cb> (this);
		2070
		2071	io.start (fd, ev::READ);
		2072	}
		2073
		2074
		2075
		2076
		2077	</pre>
		2078
1309	</div>	2079	</div>
1310	<h1 id="AUTHOR">AUTHOR</h1><p><a href="#TOP" class="toplink">Top</a></p>	2080	<h1 id="MACRO_MAGIC">MACRO MAGIC</h1>
		2081	<div id="MACRO_MAGIC_CONTENT">
		2082	<p>Libev can be compiled with a variety of options, the most fundemantal is
		2083	<code>EV_MULTIPLICITY</code>. This option determines whether (most) functions and
		2084	callbacks have an initial <code>struct ev_loop *</code> argument.</p>
		2085	<p>To make it easier to write programs that cope with either variant, the
		2086	following macros are defined:</p>
		2087	<dl>
		2088	<dt><code>EV_A</code>, <code>EV_A_</code></dt>
		2089	<dd>
		2090	<p>This provides the loop <i>argument</i> for functions, if one is required ("ev
		2091	loop argument"). The <code>EV_A</code> form is used when this is the sole argument,
		2092	<code>EV_A_</code> is used when other arguments are following. Example:</p>
		2093	<pre> ev_unref (EV_A);
		2094	ev_timer_add (EV_A_ watcher);
		2095	ev_loop (EV_A_ 0);
		2096
		2097	</pre>
		2098	<p>It assumes the variable <code>loop</code> of type <code>struct ev_loop *</code> is in scope,
		2099	which is often provided by the following macro.</p>
		2100	</dd>
		2101	<dt><code>EV_P</code>, <code>EV_P_</code></dt>
		2102	<dd>
		2103	<p>This provides the loop <i>parameter</i> for functions, if one is required ("ev
		2104	loop parameter"). The <code>EV_P</code> form is used when this is the sole parameter,
		2105	<code>EV_P_</code> is used when other parameters are following. Example:</p>
		2106	<pre> // this is how ev_unref is being declared
		2107	static void ev_unref (EV_P);
		2108
		2109	// this is how you can declare your typical callback
		2110	static void cb (EV_P_ ev_timer *w, int revents)
		2111
		2112	</pre>
		2113	<p>It declares a parameter <code>loop</code> of type <code>struct ev_loop *</code>, quite
		2114	suitable for use with <code>EV_A</code>.</p>
		2115	</dd>
		2116	<dt><code>EV_DEFAULT</code>, <code>EV_DEFAULT_</code></dt>
		2117	<dd>
		2118	<p>Similar to the other two macros, this gives you the value of the default
		2119	loop, if multiple loops are supported ("ev loop default").</p>
		2120	</dd>
		2121	</dl>
		2122	<p>Example: Declare and initialise a check watcher, utilising the above
		2123	macros so it will work regardless of whether multiple loops are supported
		2124	or not.</p>
		2125	<pre> static void
		2126	check_cb (EV_P_ ev_timer *w, int revents)
		2127	{
		2128	ev_check_stop (EV_A_ w);
		2129	}
		2130
		2131	ev_check check;
		2132	ev_check_init (&check, check_cb);
		2133	ev_check_start (EV_DEFAULT_ &check);
		2134	ev_loop (EV_DEFAULT_ 0);
		2135
		2136	</pre>
		2137
		2138	</div>
		2139	<h1 id="EMBEDDING">EMBEDDING</h1>
		2140	<div id="EMBEDDING_CONTENT">
		2141	<p>Libev can (and often is) directly embedded into host
		2142	applications. Examples of applications that embed it include the Deliantra
		2143	Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe)
		2144	and rxvt-unicode.</p>
		2145	<p>The goal is to enable you to just copy the neecssary files into your
		2146	source directory without having to change even a single line in them, so
		2147	you can easily upgrade by simply copying (or having a checked-out copy of
		2148	libev somewhere in your source tree).</p>
		2149
		2150	</div>
		2151	<h2 id="FILESETS">FILESETS</h2>
		2152	<div id="FILESETS_CONTENT">
		2153	<p>Depending on what features you need you need to include one or more sets of files
		2154	in your app.</p>
		2155
		2156	</div>
		2157	<h3 id="CORE_EVENT_LOOP">CORE EVENT LOOP</h3>
		2158	<div id="CORE_EVENT_LOOP_CONTENT">
		2159	<p>To include only the libev core (all the <code>ev_*</code> functions), with manual
		2160	configuration (no autoconf):</p>
		2161	<pre> #define EV_STANDALONE 1
		2162	#include "ev.c"
		2163
		2164	</pre>
		2165	<p>This will automatically include <cite>ev.h</cite>, too, and should be done in a
		2166	single C source file only to provide the function implementations. To use
		2167	it, do the same for <cite>ev.h</cite> in all files wishing to use this API (best
		2168	done by writing a wrapper around <cite>ev.h</cite> that you can include instead and
		2169	where you can put other configuration options):</p>
		2170	<pre> #define EV_STANDALONE 1
		2171	#include "ev.h"
		2172
		2173	</pre>
		2174	<p>Both header files and implementation files can be compiled with a C++
		2175	compiler (at least, thats a stated goal, and breakage will be treated
		2176	as a bug).</p>
		2177	<p>You need the following files in your source tree, or in a directory
		2178	in your include path (e.g. in libev/ when using -Ilibev):</p>
		2179	<pre> ev.h
		2180	ev.c
		2181	ev_vars.h
		2182	ev_wrap.h
		2183
		2184	ev_win32.c required on win32 platforms only
		2185
		2186	ev_select.c only when select backend is enabled (which is enabled by default)
		2187	ev_poll.c only when poll backend is enabled (disabled by default)
		2188	ev_epoll.c only when the epoll backend is enabled (disabled by default)
		2189	ev_kqueue.c only when the kqueue backend is enabled (disabled by default)
		2190	ev_port.c only when the solaris port backend is enabled (disabled by default)
		2191
		2192	</pre>
		2193	<p><cite>ev.c</cite> includes the backend files directly when enabled, so you only need
		2194	to compile this single file.</p>
		2195
		2196	</div>
		2197	<h3 id="LIBEVENT_COMPATIBILITY_API">LIBEVENT COMPATIBILITY API</h3>
		2198	<div id="LIBEVENT_COMPATIBILITY_API_CONTENT">
		2199	<p>To include the libevent compatibility API, also include:</p>
		2200	<pre> #include "event.c"
		2201
		2202	</pre>
		2203	<p>in the file including <cite>ev.c</cite>, and:</p>
		2204	<pre> #include "event.h"
		2205
		2206	</pre>
		2207	<p>in the files that want to use the libevent API. This also includes <cite>ev.h</cite>.</p>
		2208	<p>You need the following additional files for this:</p>
		2209	<pre> event.h
		2210	event.c
		2211
		2212	</pre>
		2213
		2214	</div>
		2215	<h3 id="AUTOCONF_SUPPORT">AUTOCONF SUPPORT</h3>
		2216	<div id="AUTOCONF_SUPPORT_CONTENT">
		2217	<p>Instead of using <code>EV_STANDALONE=1</code> and providing your config in
		2218	whatever way you want, you can also <code>m4_include([libev.m4])</code> in your
		2219	<cite>configure.ac</cite> and leave <code>EV_STANDALONE</code> undefined. <cite>ev.c</cite> will then
		2220	include <cite>config.h</cite> and configure itself accordingly.</p>
		2221	<p>For this of course you need the m4 file:</p>
		2222	<pre> libev.m4
		2223
		2224	</pre>
		2225
		2226	</div>
		2227	<h2 id="PREPROCESSOR_SYMBOLS_MACROS">PREPROCESSOR SYMBOLS/MACROS</h2>
		2228	<div id="PREPROCESSOR_SYMBOLS_MACROS_CONTENT">
		2229	<p>Libev can be configured via a variety of preprocessor symbols you have to define
		2230	before including any of its files. The default is not to build for multiplicity
		2231	and only include the select backend.</p>
		2232	<dl>
		2233	<dt>EV_STANDALONE</dt>
		2234	<dd>
		2235	<p>Must always be <code>1</code> if you do not use autoconf configuration, which
		2236	keeps libev from including <cite>config.h</cite>, and it also defines dummy
		2237	implementations for some libevent functions (such as logging, which is not
		2238	supported). It will also not define any of the structs usually found in
		2239	<cite>event.h</cite> that are not directly supported by the libev core alone.</p>
		2240	</dd>
		2241	<dt>EV_USE_MONOTONIC</dt>
		2242	<dd>
		2243	<p>If defined to be <code>1</code>, libev will try to detect the availability of the
		2244	monotonic clock option at both compiletime and runtime. Otherwise no use
		2245	of the monotonic clock option will be attempted. If you enable this, you
		2246	usually have to link against librt or something similar. Enabling it when
		2247	the functionality isn't available is safe, though, althoguh you have
		2248	to make sure you link against any libraries where the <code>clock_gettime</code>
		2249	function is hiding in (often <cite>-lrt</cite>).</p>
		2250	</dd>
		2251	<dt>EV_USE_REALTIME</dt>
		2252	<dd>
		2253	<p>If defined to be <code>1</code>, libev will try to detect the availability of the
		2254	realtime clock option at compiletime (and assume its availability at
		2255	runtime if successful). Otherwise no use of the realtime clock option will
		2256	be attempted. This effectively replaces <code>gettimeofday</code> by <code>clock_get
		2257	(CLOCK_REALTIME, ...)</code> and will not normally affect correctness. See tzhe note about libraries
		2258	in the description of <code>EV_USE_MONOTONIC</code>, though.</p>
		2259	</dd>
		2260	<dt>EV_USE_SELECT</dt>
		2261	<dd>
		2262	<p>If undefined or defined to be <code>1</code>, libev will compile in support for the
		2263	<code>select</code>(2) backend. No attempt at autodetection will be done: if no
		2264	other method takes over, select will be it. Otherwise the select backend
		2265	will not be compiled in.</p>
		2266	</dd>
		2267	<dt>EV_SELECT_USE_FD_SET</dt>
		2268	<dd>
		2269	<p>If defined to <code>1</code>, then the select backend will use the system <code>fd_set</code>
		2270	structure. This is useful if libev doesn't compile due to a missing
		2271	<code>NFDBITS</code> or <code>fd_mask</code> definition or it misguesses the bitset layout on
		2272	exotic systems. This usually limits the range of file descriptors to some
		2273	low limit such as 1024 or might have other limitations (winsocket only
		2274	allows 64 sockets). The <code>FD_SETSIZE</code> macro, set before compilation, might
		2275	influence the size of the <code>fd_set</code> used.</p>
		2276	</dd>
		2277	<dt>EV_SELECT_IS_WINSOCKET</dt>
		2278	<dd>
		2279	<p>When defined to <code>1</code>, the select backend will assume that
		2280	select/socket/connect etc. don't understand file descriptors but
		2281	wants osf handles on win32 (this is the case when the select to
		2282	be used is the winsock select). This means that it will call
		2283	<code>_get_osfhandle</code> on the fd to convert it to an OS handle. Otherwise,
		2284	it is assumed that all these functions actually work on fds, even
		2285	on win32. Should not be defined on non-win32 platforms.</p>
		2286	</dd>
		2287	<dt>EV_USE_POLL</dt>
		2288	<dd>
		2289	<p>If defined to be <code>1</code>, libev will compile in support for the <code>poll</code>(2)
		2290	backend. Otherwise it will be enabled on non-win32 platforms. It
		2291	takes precedence over select.</p>
		2292	</dd>
		2293	<dt>EV_USE_EPOLL</dt>
		2294	<dd>
		2295	<p>If defined to be <code>1</code>, libev will compile in support for the Linux
		2296	<code>epoll</code>(7) backend. Its availability will be detected at runtime,
		2297	otherwise another method will be used as fallback. This is the
		2298	preferred backend for GNU/Linux systems.</p>
		2299	</dd>
		2300	<dt>EV_USE_KQUEUE</dt>
		2301	<dd>
		2302	<p>If defined to be <code>1</code>, libev will compile in support for the BSD style
		2303	<code>kqueue</code>(2) backend. Its actual availability will be detected at runtime,
		2304	otherwise another method will be used as fallback. This is the preferred
		2305	backend for BSD and BSD-like systems, although on most BSDs kqueue only
		2306	supports some types of fds correctly (the only platform we found that
		2307	supports ptys for example was NetBSD), so kqueue might be compiled in, but
		2308	not be used unless explicitly requested. The best way to use it is to find
		2309	out whether kqueue supports your type of fd properly and use an embedded
		2310	kqueue loop.</p>
		2311	</dd>
		2312	<dt>EV_USE_PORT</dt>
		2313	<dd>
		2314	<p>If defined to be <code>1</code>, libev will compile in support for the Solaris
		2315	10 port style backend. Its availability will be detected at runtime,
		2316	otherwise another method will be used as fallback. This is the preferred
		2317	backend for Solaris 10 systems.</p>
		2318	</dd>
		2319	<dt>EV_USE_DEVPOLL</dt>
		2320	<dd>
		2321	<p>reserved for future expansion, works like the USE symbols above.</p>
		2322	</dd>
		2323	<dt>EV_USE_INOTIFY</dt>
		2324	<dd>
		2325	<p>If defined to be <code>1</code>, libev will compile in support for the Linux inotify
		2326	interface to speed up <code>ev_stat</code> watchers. Its actual availability will
		2327	be detected at runtime.</p>
		2328	</dd>
		2329	<dt>EV_H</dt>
		2330	<dd>
		2331	<p>The name of the <cite>ev.h</cite> header file used to include it. The default if
		2332	undefined is <code><ev.h></code> in <cite>event.h</cite> and <code>"ev.h"</code> in <cite>ev.c</cite>. This
		2333	can be used to virtually rename the <cite>ev.h</cite> header file in case of conflicts.</p>
		2334	</dd>
		2335	<dt>EV_CONFIG_H</dt>
		2336	<dd>
		2337	<p>If <code>EV_STANDALONE</code> isn't <code>1</code>, this variable can be used to override
		2338	<cite>ev.c</cite>'s idea of where to find the <cite>config.h</cite> file, similarly to
		2339	<code>EV_H</code>, above.</p>
		2340	</dd>
		2341	<dt>EV_EVENT_H</dt>
		2342	<dd>
		2343	<p>Similarly to <code>EV_H</code>, this macro can be used to override <cite>event.c</cite>'s idea
		2344	of how the <cite>event.h</cite> header can be found.</p>
		2345	</dd>
		2346	<dt>EV_PROTOTYPES</dt>
		2347	<dd>
		2348	<p>If defined to be <code>0</code>, then <cite>ev.h</cite> will not define any function
		2349	prototypes, but still define all the structs and other symbols. This is
		2350	occasionally useful if you want to provide your own wrapper functions
		2351	around libev functions.</p>
		2352	</dd>
		2353	<dt>EV_MULTIPLICITY</dt>
		2354	<dd>
		2355	<p>If undefined or defined to <code>1</code>, then all event-loop-specific functions
		2356	will have the <code>struct ev_loop *</code> as first argument, and you can create
		2357	additional independent event loops. Otherwise there will be no support
		2358	for multiple event loops and there is no first event loop pointer
		2359	argument. Instead, all functions act on the single default loop.</p>
		2360	</dd>
		2361	<dt>EV_MINPRI</dt>
		2362	<dt>EV_MAXPRI</dt>
		2363	<dd>
		2364	<p>The range of allowed priorities. <code>EV_MINPRI</code> must be smaller or equal to
		2365	<code>EV_MAXPRI</code>, but otherwise there are no non-obvious limitations. You can
		2366	provide for more priorities by overriding those symbols (usually defined
		2367	to be <code>-2</code> and <code>2</code>, respectively).</p>
		2368	<p>When doing priority-based operations, libev usually has to linearly search
		2369	all the priorities, so having many of them (hundreds) uses a lot of space
		2370	and time, so using the defaults of five priorities (-2 .. +2) is usually
		2371	fine.</p>
		2372	<p>If your embedding app does not need any priorities, defining these both to
		2373	<code>0</code> will save some memory and cpu.</p>
		2374	</dd>
		2375	<dt>EV_PERIODIC_ENABLE</dt>
		2376	<dd>
		2377	<p>If undefined or defined to be <code>1</code>, then periodic timers are supported. If
		2378	defined to be <code>0</code>, then they are not. Disabling them saves a few kB of
		2379	code.</p>
		2380	</dd>
		2381	<dt>EV_IDLE_ENABLE</dt>
		2382	<dd>
		2383	<p>If undefined or defined to be <code>1</code>, then idle watchers are supported. If
		2384	defined to be <code>0</code>, then they are not. Disabling them saves a few kB of
		2385	code.</p>
		2386	</dd>
		2387	<dt>EV_EMBED_ENABLE</dt>
		2388	<dd>
		2389	<p>If undefined or defined to be <code>1</code>, then embed watchers are supported. If
		2390	defined to be <code>0</code>, then they are not.</p>
		2391	</dd>
		2392	<dt>EV_STAT_ENABLE</dt>
		2393	<dd>
		2394	<p>If undefined or defined to be <code>1</code>, then stat watchers are supported. If
		2395	defined to be <code>0</code>, then they are not.</p>
		2396	</dd>
		2397	<dt>EV_FORK_ENABLE</dt>
		2398	<dd>
		2399	<p>If undefined or defined to be <code>1</code>, then fork watchers are supported. If
		2400	defined to be <code>0</code>, then they are not.</p>
		2401	</dd>
		2402	<dt>EV_MINIMAL</dt>
		2403	<dd>
		2404	<p>If you need to shave off some kilobytes of code at the expense of some
		2405	speed, define this symbol to <code>1</code>. Currently only used for gcc to override
		2406	some inlining decisions, saves roughly 30% codesize of amd64.</p>
		2407	</dd>
		2408	<dt>EV_PID_HASHSIZE</dt>
		2409	<dd>
		2410	<p><code>ev_child</code> watchers use a small hash table to distribute workload by
		2411	pid. The default size is <code>16</code> (or <code>1</code> with <code>EV_MINIMAL</code>), usually more
		2412	than enough. If you need to manage thousands of children you might want to
		2413	increase this value (<i>must</i> be a power of two).</p>
		2414	</dd>
		2415	<dt>EV_INOTIFY_HASHSIZE</dt>
		2416	<dd>
		2417	<p><code>ev_staz</code> watchers use a small hash table to distribute workload by
		2418	inotify watch id. The default size is <code>16</code> (or <code>1</code> with <code>EV_MINIMAL</code>),
		2419	usually more than enough. If you need to manage thousands of <code>ev_stat</code>
		2420	watchers you might want to increase this value (<i>must</i> be a power of
		2421	two).</p>
		2422	</dd>
		2423	<dt>EV_COMMON</dt>
		2424	<dd>
		2425	<p>By default, all watchers have a <code>void *data</code> member. By redefining
		2426	this macro to a something else you can include more and other types of
		2427	members. You have to define it each time you include one of the files,
		2428	though, and it must be identical each time.</p>
		2429	<p>For example, the perl EV module uses something like this:</p>
		2430	<pre> #define EV_COMMON \
		2431	SV self; / contains this struct */ \
		2432	SV cb_sv, fh /* note no trailing ";" */
		2433
		2434	</pre>
		2435	</dd>
		2436	<dt>EV_CB_DECLARE (type)</dt>
		2437	<dt>EV_CB_INVOKE (watcher, revents)</dt>
		2438	<dt>ev_set_cb (ev, cb)</dt>
		2439	<dd>
		2440	<p>Can be used to change the callback member declaration in each watcher,
		2441	and the way callbacks are invoked and set. Must expand to a struct member
		2442	definition and a statement, respectively. See the <cite>ev.v</cite> header file for
		2443	their default definitions. One possible use for overriding these is to
		2444	avoid the <code>struct ev_loop *</code> as first argument in all cases, or to use
		2445	method calls instead of plain function calls in C++.</p>
		2446
		2447	</div>
		2448	<h2 id="EXAMPLES">EXAMPLES</h2>
		2449	<div id="EXAMPLES_CONTENT">
		2450	<p>For a real-world example of a program the includes libev
		2451	verbatim, you can have a look at the EV perl module
		2452	(<a href="http://software.schmorp.de/pkg/EV.html">http://software.schmorp.de/pkg/EV.html</a>). It has the libev files in
		2453	the <cite>libev/</cite> subdirectory and includes them in the <cite>EV/EVAPI.h</cite> (public
		2454	interface) and <cite>EV.xs</cite> (implementation) files. Only the <cite>EV.xs</cite> file
		2455	will be compiled. It is pretty complex because it provides its own header
		2456	file.</p>
		2457	<p>The usage in rxvt-unicode is simpler. It has a <cite>ev_cpp.h</cite> header file
		2458	that everybody includes and which overrides some configure choices:</p>
		2459	<pre> #define EV_MINIMAL 1
		2460	#define EV_USE_POLL 0
		2461	#define EV_MULTIPLICITY 0
		2462	#define EV_PERIODIC_ENABLE 0
		2463	#define EV_STAT_ENABLE 0
		2464	#define EV_FORK_ENABLE 0
		2465	#define EV_CONFIG_H <config.h>
		2466	#define EV_MINPRI 0
		2467	#define EV_MAXPRI 0
		2468
		2469	#include "ev++.h"
		2470
		2471	</pre>
		2472	<p>And a <cite>ev_cpp.C</cite> implementation file that contains libev proper and is compiled:</p>
		2473	<pre> #include "ev_cpp.h"
		2474	#include "ev.c"
		2475
		2476
		2477
		2478
		2479	</pre>
		2480
		2481	</div>
		2482	<h1 id="COMPLEXITIES">COMPLEXITIES</h1>
		2483	<div id="COMPLEXITIES_CONTENT">
		2484	<p>In this section the complexities of (many of) the algorithms used inside
		2485	libev will be explained. For complexity discussions about backends see the
		2486	documentation for <code>ev_default_init</code>.</p>
		2487	<p>All of the following are about amortised time: If an array needs to be
		2488	extended, libev needs to realloc and move the whole array, but this
		2489	happens asymptotically never with higher number of elements, so O(1) might
		2490	mean it might do a lengthy realloc operation in rare cases, but on average
		2491	it is much faster and asymptotically approaches constant time.</p>
		2492	<p>
		2493	<dl>
		2494	<dt>Starting and stopping timer/periodic watchers: O(log skipped_other_timers)</dt>
		2495	<dd>
		2496	<p>This means that, when you have a watcher that triggers in one hour and
		2497	there are 100 watchers that would trigger before that then inserting will
		2498	have to skip those 100 watchers.</p>
		2499	</dd>
		2500	<dt>Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)</dt>
		2501	<dd>
		2502	<p>That means that for changing a timer costs less than removing/adding them
		2503	as only the relative motion in the event queue has to be paid for.</p>
		2504	</dd>
		2505	<dt>Starting io/check/prepare/idle/signal/child watchers: O(1)</dt>
		2506	<dd>
		2507	<p>These just add the watcher into an array or at the head of a list.
		2508	=item Stopping check/prepare/idle watchers: O(1)</p>
		2509	</dd>
		2510	<dt>Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))</dt>
		2511	<dd>
		2512	<p>These watchers are stored in lists then need to be walked to find the
		2513	correct watcher to remove. The lists are usually short (you don't usually
		2514	have many watchers waiting for the same fd or signal).</p>
		2515	</dd>
		2516	<dt>Finding the next timer per loop iteration: O(1)</dt>
		2517	<dt>Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)</dt>
		2518	<dd>
		2519	<p>A change means an I/O watcher gets started or stopped, which requires
		2520	libev to recalculate its status (and possibly tell the kernel).</p>
		2521	</dd>
		2522	<dt>Activating one watcher: O(1)</dt>
		2523	<dt>Priority handling: O(number_of_priorities)</dt>
		2524	<dd>
		2525	<p>Priorities are implemented by allocating some space for each
		2526	priority. When doing priority-based operations, libev usually has to
		2527	linearly search all the priorities.</p>
		2528	</dd>
		2529	</dl>
		2530	</p>
		2531
		2532
		2533
		2534
		2535
		2536	</div>
		2537	<h1 id="AUTHOR">AUTHOR</h1>
1311	<div id="AUTHOR_CONTENT">	2538	<div id="AUTHOR_CONTENT">
1312	<p>Marc Lehmann <libev@schmorp.de>.</p>	2539	<p>Marc Lehmann <libev@schmorp.de>.</p>
1313		2540
1314	</div>	2541	</div>
1315	</div></body>	2542	</div></body>
1316	</html>	2543	</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 1.78 by root, Wed Dec 12 17:55:06 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 1.78 by root, Wed Dec 12 17:55:06 2007 UTC