[ViewVC] Diff of: cvs/libev/ev.html

Comparing libev/ev.html (file contents):
Revision 1.12 by root, Mon Nov 12 08:35:18 2007 UTC vs.
Revision 1.57 by root, Wed Nov 28 11:27:29 2007 UTC

…		…
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="Mon Nov 12 09:35:17 2007" />	9	<meta name="created" content="Wed Nov 28 12:27:27 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>
		23	<li><a href="#TIME_REPRESENTATION">TIME REPRESENTATION</a></li>
22	<li><a href="#TIME_AND_OTHER_GLOBAL_FUNCTIONS">TIME AND OTHER GLOBAL FUNCTIONS</a></li>	24	<li><a href="#GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</a></li>
23	<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>
24	<li><a href="#ANATOMY_OF_A_WATCHER">ANATOMY OF A WATCHER</a>	26	<li><a href="#ANATOMY_OF_A_WATCHER">ANATOMY OF A WATCHER</a>
		27	<ul><li><a href="#GENERIC_WATCHER_FUNCTIONS">GENERIC WATCHER FUNCTIONS</a></li>
25	<ul><li><a href="#ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH">ASSOCIATING CUSTOM DATA WITH A WATCHER</a></li>	28	<li><a href="#ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH">ASSOCIATING CUSTOM DATA WITH A WATCHER</a></li>
26	</ul>	29	</ul>
27	</li>	30	</li>
28	<li><a href="#WATCHER_TYPES">WATCHER TYPES</a>	31	<li><a href="#WATCHER_TYPES">WATCHER TYPES</a>
29	<ul><li><a href="#code_ev_io_code_is_this_file_descrip"><code>ev_io</code> - is this file descriptor readable or writable</a></li>	32	<ul><li><a href="#code_ev_io_code_is_this_file_descrip"><code>ev_io</code> - is this file descriptor readable or writable?</a></li>
30	<li><a href="#code_ev_timer_code_relative_and_opti"><code>ev_timer</code> - relative and optionally recurring timeouts</a></li>	33	<li><a href="#code_ev_timer_code_relative_and_opti"><code>ev_timer</code> - relative and optionally repeating timeouts</a></li>
31	<li><a href="#code_ev_periodic_code_to_cron_or_not"><code>ev_periodic</code> - to cron or not to cron it</a></li>	34	<li><a href="#code_ev_periodic_code_to_cron_or_not"><code>ev_periodic</code> - to cron or not to cron?</a></li>
32	<li><a href="#code_ev_signal_code_signal_me_when_a"><code>ev_signal</code> - signal me when a signal gets signalled</a></li>	35	<li><a href="#code_ev_signal_code_signal_me_when_a"><code>ev_signal</code> - signal me when a signal gets signalled!</a></li>
33	<li><a href="#code_ev_child_code_wait_for_pid_stat"><code>ev_child</code> - wait for pid status changes</a></li>	36	<li><a href="#code_ev_child_code_watch_out_for_pro"><code>ev_child</code> - watch out for process status changes</a></li>
		37	<li><a href="#code_ev_stat_code_did_the_file_attri"><code>ev_stat</code> - did the file attributes just change?</a></li>
34	<li><a href="#code_ev_idle_code_when_you_ve_got_no"><code>ev_idle</code> - when you've got nothing better to do</a></li>	38	<li><a href="#code_ev_idle_code_when_you_ve_got_no"><code>ev_idle</code> - when you've got nothing better to do...</a></li>
35	<li><a href="#prepare_and_check_your_hooks_into_th">prepare and check - your hooks into the event loop</a></li>	39	<li><a href="#code_ev_prepare_code_and_code_ev_che"><code>ev_prepare</code> and <code>ev_check</code> - customise your event loop!</a></li>
		40	<li><a href="#code_ev_embed_code_when_one_backend_"><code>ev_embed</code> - when one backend isn't enough...</a></li>
		41	<li><a href="#code_ev_fork_code_the_audacity_to_re"><code>ev_fork</code> - the audacity to resume the event loop after a fork</a></li>
36	</ul>	42	</ul>
37	</li>	43	</li>
38	<li><a href="#OTHER_FUNCTIONS">OTHER FUNCTIONS</a></li>	44	<li><a href="#OTHER_FUNCTIONS">OTHER FUNCTIONS</a></li>
		45	<li><a href="#LIBEVENT_EMULATION">LIBEVENT EMULATION</a></li>
		46	<li><a href="#C_SUPPORT">C++ SUPPORT</a></li>
		47	<li><a href="#MACRO_MAGIC">MACRO MAGIC</a></li>
		48	<li><a href="#EMBEDDING">EMBEDDING</a>
		49	<ul><li><a href="#FILESETS">FILESETS</a>
		50	<ul><li><a href="#CORE_EVENT_LOOP">CORE EVENT LOOP</a></li>
		51	<li><a href="#LIBEVENT_COMPATIBILITY_API">LIBEVENT COMPATIBILITY API</a></li>
		52	<li><a href="#AUTOCONF_SUPPORT">AUTOCONF SUPPORT</a></li>
		53	</ul>
		54	</li>
		55	<li><a href="#PREPROCESSOR_SYMBOLS_MACROS">PREPROCESSOR SYMBOLS/MACROS</a></li>
		56	<li><a href="#EXAMPLES">EXAMPLES</a></li>
		57	</ul>
		58	</li>
		59	<li><a href="#COMPLEXITIES">COMPLEXITIES</a></li>
39	<li><a href="#AUTHOR">AUTHOR</a>	60	<li><a href="#AUTHOR">AUTHOR</a>
40	</li>	61	</li>
41	</ul><hr />	62	</ul><hr />
42	<!-- INDEX END -->	63	<!-- INDEX END -->
43		64
44	<h1 id="NAME">NAME</h1><p><a href="#TOP" class="toplink">Top</a></p>	65	<h1 id="NAME">NAME</h1>
45	<div id="NAME_CONTENT">	66	<div id="NAME_CONTENT">
46	<p>libev - a high performance full-featured event loop written in C</p>	67	<p>libev - a high performance full-featured event loop written in C</p>
47		68
48	</div>	69	</div>
49	<h1 id="SYNOPSIS">SYNOPSIS</h1><p><a href="#TOP" class="toplink">Top</a></p>	70	<h1 id="SYNOPSIS">SYNOPSIS</h1>
50	<div id="SYNOPSIS_CONTENT">	71	<div id="SYNOPSIS_CONTENT">
51	<pre> #include <ev.h>	72	<pre> #include <ev.h>
52		73
53	</pre>	74	</pre>
54		75
55	</div>	76	</div>
56	<h1 id="DESCRIPTION">DESCRIPTION</h1><p><a href="#TOP" class="toplink">Top</a></p>	77	<h1 id="EXAMPLE_PROGRAM">EXAMPLE PROGRAM</h1>
		78	<div id="EXAMPLE_PROGRAM_CONTENT">
		79	<pre> #include <ev.h>
		80
		81	ev_io stdin_watcher;
		82	ev_timer timeout_watcher;
		83
		84	/* called when data readable on stdin */
		85	static void
		86	stdin_cb (EV_P_ struct ev_io *w, int revents)
		87	{
		88	/* puts ("stdin ready"); */
		89	ev_io_stop (EV_A_ w); /* just a syntax example */
		90	ev_unloop (EV_A_ EVUNLOOP_ALL); /* leave all loop calls */
		91	}
		92
		93	static void
		94	timeout_cb (EV_P_ struct ev_timer *w, int revents)
		95	{
		96	/* puts ("timeout"); */
		97	ev_unloop (EV_A_ EVUNLOOP_ONE); /* leave one loop call */
		98	}
		99
		100	int
		101	main (void)
		102	{
		103	struct ev_loop *loop = ev_default_loop (0);
		104
		105	/* initialise an io watcher, then start it */
		106	ev_io_init (&stdin_watcher, stdin_cb, /STDIN_FILENO/ 0, EV_READ);
		107	ev_io_start (loop, &stdin_watcher);
		108
		109	/* simple non-repeating 5.5 second timeout */
		110	ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.);
		111	ev_timer_start (loop, &timeout_watcher);
		112
		113	/* loop till timeout or data ready */
		114	ev_loop (loop, 0);
		115
		116	return 0;
		117	}
		118
		119	</pre>
		120
		121	</div>
		122	<h1 id="DESCRIPTION">DESCRIPTION</h1>
57	<div id="DESCRIPTION_CONTENT">	123	<div id="DESCRIPTION_CONTENT">
58	<p>Libev is an event loop: you register interest in certain events (such as a	124	<p>Libev is an event loop: you register interest in certain events (such as a
59	file descriptor being readable or a timeout occuring), and it will manage	125	file descriptor being readable or a timeout occuring), and it will manage
60	these event sources and provide your program with events.</p>	126	these event sources and provide your program with events.</p>
61	<p>To do this, it must take more or less complete control over your process	127	<p>To do this, it must take more or less complete control over your process
…		…
65	watchers</i>, which are relatively small C structures you initialise with the	131	watchers</i>, which are relatively small C structures you initialise with the
66	details of the event, and then hand it over to libev by <i>starting</i> the	132	details of the event, and then hand it over to libev by <i>starting</i> the
67	watcher.</p>	133	watcher.</p>
68		134
69	</div>	135	</div>
70	<h1 id="FEATURES">FEATURES</h1><p><a href="#TOP" class="toplink">Top</a></p>	136	<h1 id="FEATURES">FEATURES</h1>
71	<div id="FEATURES_CONTENT">	137	<div id="FEATURES_CONTENT">
72	<p>Libev supports select, poll, the linux-specific epoll and the bsd-specific	138	<p>Libev supports <code>select</code>, <code>poll</code>, the linux-specific <code>epoll</code>, the
73	kqueue mechanisms for file descriptor events, relative timers, absolute	139	bsd-specific <code>kqueue</code> and the solaris-specific event port mechanisms
74	timers with customised rescheduling, signal events, process status change	140	for file descriptor events (<code>ev_io</code>), relative timers (<code>ev_timer</code>),
75	events (related to SIGCHLD), and event watchers dealing with the event	141	absolute timers with customised rescheduling (<code>ev_periodic</code>), synchronous
76	loop mechanism itself (idle, prepare and check watchers). It also is quite	142	signals (<code>ev_signal</code>), process status change events (<code>ev_child</code>), and
		143	event watchers dealing with the event loop mechanism itself (<code>ev_idle</code>,
		144	<code>ev_embed</code>, <code>ev_prepare</code> and <code>ev_check</code> watchers) as well as
		145	file watchers (<code>ev_stat</code>) and even limited support for fork events
		146	(<code>ev_fork</code>).</p>
		147	<p>It also is quite fast (see this
77	fast (see this <a href="http://libev.schmorp.de/bench.html">benchmark</a> comparing	148	<a href="http://libev.schmorp.de/bench.html">benchmark</a> comparing it to libevent
78	it to libevent for example).</p>	149	for example).</p>
79		150
80	</div>	151	</div>
81	<h1 id="CONVENTIONS">CONVENTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p>	152	<h1 id="CONVENTIONS">CONVENTIONS</h1>
82	<div id="CONVENTIONS_CONTENT">	153	<div id="CONVENTIONS_CONTENT">
83	<p>Libev is very configurable. In this manual the default configuration	154	<p>Libev is very configurable. In this manual the default configuration will
84	will be described, which supports multiple event loops. For more info	155	be described, which supports multiple event loops. For more info about
85	about various configuration options please have a look at the file	156	various configuration options please have a look at <strong>EMBED</strong> section in
86	<cite>README.embed</cite> in the libev distribution. If libev was configured without	157	this manual. If libev was configured without support for multiple event
87	support for multiple event loops, then all functions taking an initial	158	loops, then all functions taking an initial argument of name <code>loop</code>
88	argument of name <code>loop</code> (which is always of type <code>struct ev_loop *</code>)	159	(which is always of type <code>struct ev_loop *</code>) will not have this argument.</p>
89	will not have this argument.</p>
90		160
91	</div>	161	</div>
92	<h1 id="TIME_AND_OTHER_GLOBAL_FUNCTIONS">TIME AND OTHER GLOBAL FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p>	162	<h1 id="TIME_REPRESENTATION">TIME REPRESENTATION</h1>
93	<div id="TIME_AND_OTHER_GLOBAL_FUNCTIONS_CONT">	163	<div id="TIME_REPRESENTATION_CONTENT">
94	<p>Libev represents time as a single floating point number, representing the	164	<p>Libev represents time as a single floating point number, representing the
95	(fractional) number of seconds since the (POSIX) epoch (somewhere near	165	(fractional) number of seconds since the (POSIX) epoch (somewhere near
96	the beginning of 1970, details are complicated, don't ask). This type is	166	the beginning of 1970, details are complicated, don't ask). This type is
97	called <code>ev_tstamp</code>, which is what you should use too. It usually aliases	167	called <code>ev_tstamp</code>, which is what you should use too. It usually aliases
98	to the double type in C.</p>	168	to the <code>double</code> type in C, and when you need to do any calculations on
		169	it, you should treat it as such.</p>
		170
		171	</div>
		172	<h1 id="GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</h1>
		173	<div id="GLOBAL_FUNCTIONS_CONTENT">
		174	<p>These functions can be called anytime, even before initialising the
		175	library in any way.</p>
99	<dl>	176	<dl>
100	<dt>ev_tstamp ev_time ()</dt>	177	<dt>ev_tstamp ev_time ()</dt>
101	<dd>	178	<dd>
102	<p>Returns the current time as libev would use it.</p>	179	<p>Returns the current time as libev would use it. Please note that the
		180	<code>ev_now</code> function is usually faster and also often returns the timestamp
		181	you actually want to know.</p>
103	</dd>	182	</dd>
104	<dt>int ev_version_major ()</dt>	183	<dt>int ev_version_major ()</dt>
105	<dt>int ev_version_minor ()</dt>	184	<dt>int ev_version_minor ()</dt>
106	<dd>	185	<dd>
107	<p>You can find out the major and minor version numbers of the library	186	<p>You can find out the major and minor version numbers of the library
…		…
111	version of the library your program was compiled against.</p>	190	version of the library your program was compiled against.</p>
112	<p>Usually, it's a good idea to terminate if the major versions mismatch,	191	<p>Usually, it's a good idea to terminate if the major versions mismatch,
113	as this indicates an incompatible change. Minor versions are usually	192	as this indicates an incompatible change. Minor versions are usually
114	compatible to older versions, so a larger minor version alone is usually	193	compatible to older versions, so a larger minor version alone is usually
115	not a problem.</p>	194	not a problem.</p>
		195	<p>Example: Make sure we haven't accidentally been linked against the wrong
		196	version.</p>
		197	<pre> assert (("libev version mismatch",
		198	ev_version_major () == EV_VERSION_MAJOR
		199	&& ev_version_minor () >= EV_VERSION_MINOR));
		200
		201	</pre>
		202	</dd>
		203	<dt>unsigned int ev_supported_backends ()</dt>
116	</dd>	204	<dd>
		205	<p>Return the set of all backends (i.e. their corresponding <code>EV_BACKEND_*</code>
		206	value) compiled into this binary of libev (independent of their
		207	availability on the system you are running on). See <code>ev_default_loop</code> for
		208	a description of the set values.</p>
		209	<p>Example: make sure we have the epoll method, because yeah this is cool and
		210	a must have and can we have a torrent of it please!!!11</p>
		211	<pre> assert (("sorry, no epoll, no sex",
		212	ev_supported_backends () & EVBACKEND_EPOLL));
		213
		214	</pre>
		215	</dd>
		216	<dt>unsigned int ev_recommended_backends ()</dt>
		217	<dd>
		218	<p>Return the set of all backends compiled into this binary of libev and also
		219	recommended for this platform. This set is often smaller than the one
		220	returned by <code>ev_supported_backends</code>, as for example kqueue is broken on
		221	most BSDs and will not be autodetected unless you explicitly request it
		222	(assuming you know what you are doing). This is the set of backends that
		223	libev will probe for if you specify no backends explicitly.</p>
		224	</dd>
		225	<dt>unsigned int ev_embeddable_backends ()</dt>
		226	<dd>
		227	<p>Returns the set of backends that are embeddable in other event loops. This
		228	is the theoretical, all-platform, value. To find which backends
		229	might be supported on the current system, you would need to look at
		230	<code>ev_embeddable_backends () & ev_supported_backends ()</code>, likewise for
		231	recommended ones.</p>
		232	<p>See the description of <code>ev_embed</code> watchers for more info.</p>
		233	</dd>
117	<dt>ev_set_allocator (void (cb)(void *ptr, long size))</dt>	234	<dt>ev_set_allocator (void (cb)(void *ptr, size_t size))</dt>
118	<dd>	235	<dd>
119	<p>Sets the allocation function to use (the prototype is similar to the	236	<p>Sets the allocation function to use (the prototype and semantics are
120	realloc C function, the semantics are identical). It is used to allocate	237	identical to the realloc C function). It is used to allocate and free
121	and free memory (no surprises here). If it returns zero when memory	238	memory (no surprises here). If it returns zero when memory needs to be
122	needs to be allocated, the library might abort or take some potentially	239	allocated, the library might abort or take some potentially destructive
123	destructive action. The default is your system realloc function.</p>	240	action. The default is your system realloc function.</p>
124	<p>You could override this function in high-availability programs to, say,	241	<p>You could override this function in high-availability programs to, say,
125	free some memory if it cannot allocate memory, to use a special allocator,	242	free some memory if it cannot allocate memory, to use a special allocator,
126	or even to sleep a while and retry until some memory is available.</p>	243	or even to sleep a while and retry until some memory is available.</p>
		244	<p>Example: Replace the libev allocator with one that waits a bit and then
		245	retries).</p>
		246	<pre> static void *
		247	persistent_realloc (void *ptr, size_t size)
		248	{
		249	for (;;)
		250	{
		251	void *newptr = realloc (ptr, size);
		252
		253	if (newptr)
		254	return newptr;
		255
		256	sleep (60);
		257	}
		258	}
		259
		260	...
		261	ev_set_allocator (persistent_realloc);
		262
		263	</pre>
127	</dd>	264	</dd>
128	<dt>ev_set_syserr_cb (void (cb)(const char msg));</dt>	265	<dt>ev_set_syserr_cb (void (cb)(const char msg));</dt>
129	<dd>	266	<dd>
130	<p>Set the callback function to call on a retryable syscall error (such	267	<p>Set the callback function to call on a retryable syscall error (such
131	as failed select, poll, epoll_wait). The message is a printable string	268	as failed select, poll, epoll_wait). The message is a printable string
132	indicating the system call or subsystem causing the problem. If this	269	indicating the system call or subsystem causing the problem. If this
133	callback is set, then libev will expect it to remedy the sitution, no	270	callback is set, then libev will expect it to remedy the sitution, no
134	matter what, when it returns. That is, libev will generally retry the	271	matter what, when it returns. That is, libev will generally retry the
135	requested operation, or, if the condition doesn't go away, do bad stuff	272	requested operation, or, if the condition doesn't go away, do bad stuff
136	(such as abort).</p>	273	(such as abort).</p>
		274	<p>Example: This is basically the same thing that libev does internally, too.</p>
		275	<pre> static void
		276	fatal_error (const char *msg)
		277	{
		278	perror (msg);
		279	abort ();
		280	}
		281
		282	...
		283	ev_set_syserr_cb (fatal_error);
		284
		285	</pre>
137	</dd>	286	</dd>
138	</dl>	287	</dl>
139		288
140	</div>	289	</div>
141	<h1 id="FUNCTIONS_CONTROLLING_THE_EVENT_LOOP">FUNCTIONS CONTROLLING THE EVENT LOOP</h1><p><a href="#TOP" class="toplink">Top</a></p>	290	<h1 id="FUNCTIONS_CONTROLLING_THE_EVENT_LOOP">FUNCTIONS CONTROLLING THE EVENT LOOP</h1>
142	<div id="FUNCTIONS_CONTROLLING_THE_EVENT_LOOP-2">	291	<div id="FUNCTIONS_CONTROLLING_THE_EVENT_LOOP-2">
143	<p>An event loop is described by a <code>struct ev_loop *</code>. The library knows two	292	<p>An event loop is described by a <code>struct ev_loop *</code>. The library knows two
144	types of such loops, the <i>default</i> loop, which supports signals and child	293	types of such loops, the <i>default</i> loop, which supports signals and child
145	events, and dynamically created loops which do not.</p>	294	events, and dynamically created loops which do not.</p>
146	<p>If you use threads, a common model is to run the default event loop	295	<p>If you use threads, a common model is to run the default event loop
147	in your main thread (or in a separate thrad) and for each thread you	296	in your main thread (or in a separate thread) and for each thread you
148	create, you also create another event loop. Libev itself does no locking	297	create, you also create another event loop. Libev itself does no locking
149	whatsoever, so if you mix calls to the same event loop in different	298	whatsoever, so if you mix calls to the same event loop in different
150	threads, make sure you lock (this is usually a bad idea, though, even if	299	threads, make sure you lock (this is usually a bad idea, though, even if
151	done correctly, because it's hideous and inefficient).</p>	300	done correctly, because it's hideous and inefficient).</p>
152	<dl>	301	<dl>
153	<dt>struct ev_loop *ev_default_loop (unsigned int flags)</dt>	302	<dt>struct ev_loop *ev_default_loop (unsigned int flags)</dt>
154	<dd>	303	<dd>
155	<p>This will initialise the default event loop if it hasn't been initialised	304	<p>This will initialise the default event loop if it hasn't been initialised
156	yet and return it. If the default loop could not be initialised, returns	305	yet and return it. If the default loop could not be initialised, returns
157	false. If it already was initialised it simply returns it (and ignores the	306	false. If it already was initialised it simply returns it (and ignores the
158	flags).</p>	307	flags. If that is troubling you, check <code>ev_backend ()</code> afterwards).</p>
159	<p>If you don't know what event loop to use, use the one returned from this	308	<p>If you don't know what event loop to use, use the one returned from this
160	function.</p>	309	function.</p>
161	<p>The flags argument can be used to specify special behaviour or specific	310	<p>The flags argument can be used to specify special behaviour or specific
162	backends to use, and is usually specified as 0 (or EVFLAG_AUTO).</p>	311	backends to use, and is usually specified as <code>0</code> (or <code>EVFLAG_AUTO</code>).</p>
163	<p>It supports the following flags:</p>	312	<p>The following flags are supported:</p>
164	<p>	313	<p>
165	<dl>	314	<dl>
166	<dt><code>EVFLAG_AUTO</code></dt>	315	<dt><code>EVFLAG_AUTO</code></dt>
167	<dd>	316	<dd>
168	<p>The default flags value. Use this if you have no clue (it's the right	317	<p>The default flags value. Use this if you have no clue (it's the right
…		…
175	<code>LIBEV_FLAGS</code>. Otherwise (the default), this environment variable will	324	<code>LIBEV_FLAGS</code>. Otherwise (the default), this environment variable will
176	override the flags completely if it is found in the environment. This is	325	override the flags completely if it is found in the environment. This is
177	useful to try out specific backends to test their performance, or to work	326	useful to try out specific backends to test their performance, or to work
178	around bugs.</p>	327	around bugs.</p>
179	</dd>	328	</dd>
180	<dt><code>EVMETHOD_SELECT</code> (portable select backend)</dt>	329	<dt><code>EVBACKEND_SELECT</code> (value 1, portable select backend)</dt>
181	<dt><code>EVMETHOD_POLL</code> (poll backend, available everywhere except on windows)</dt>
182	<dt><code>EVMETHOD_EPOLL</code> (linux only)</dt>
183	<dt><code>EVMETHOD_KQUEUE</code> (some bsds only)</dt>
184	<dt><code>EVMETHOD_DEVPOLL</code> (solaris 8 only)</dt>
185	<dt><code>EVMETHOD_PORT</code> (solaris 10 only)</dt>
186	<dd>	330	<dd>
187	<p>If one or more of these are ored into the flags value, then only these	331	<p>This is your standard select(2) backend. Not <i>completely</i> standard, as
188	backends will be tried (in the reverse order as given here). If one are	332	libev tries to roll its own fd_set with no limits on the number of fds,
189	specified, any backend will do.</p>	333	but if that fails, expect a fairly low limit on the number of fds when
		334	using this backend. It doesn't scale too well (O(highest_fd)), but its usually
		335	the fastest backend for a low number of fds.</p>
		336	</dd>
		337	<dt><code>EVBACKEND_POLL</code> (value 2, poll backend, available everywhere except on windows)</dt>
		338	<dd>
		339	<p>And this is your standard poll(2) backend. It's more complicated than
		340	select, but handles sparse fds better and has no artificial limit on the
		341	number of fds you can use (except it will slow down considerably with a
		342	lot of inactive fds). It scales similarly to select, i.e. O(total_fds).</p>
		343	</dd>
		344	<dt><code>EVBACKEND_EPOLL</code> (value 4, Linux)</dt>
		345	<dd>
		346	<p>For few fds, this backend is a bit little slower than poll and select,
		347	but it scales phenomenally better. While poll and select usually scale like
		348	O(total_fds) where n is the total number of fds (or the highest fd), epoll scales
		349	either O(1) or O(active_fds).</p>
		350	<p>While stopping and starting an I/O watcher in the same iteration will
		351	result in some caching, there is still a syscall per such incident
		352	(because the fd could point to a different file description now), so its
		353	best to avoid that. Also, dup()ed file descriptors might not work very
		354	well if you register events for both fds.</p>
		355	<p>Please note that epoll sometimes generates spurious notifications, so you
		356	need to use non-blocking I/O or other means to avoid blocking when no data
		357	(or space) is available.</p>
		358	</dd>
		359	<dt><code>EVBACKEND_KQUEUE</code> (value 8, most BSD clones)</dt>
		360	<dd>
		361	<p>Kqueue deserves special mention, as at the time of this writing, it
		362	was broken on all BSDs except NetBSD (usually it doesn't work with
		363	anything but sockets and pipes, except on Darwin, where of course its
		364	completely useless). For this reason its not being "autodetected"
		365	unless you explicitly specify it explicitly in the flags (i.e. using
		366	<code>EVBACKEND_KQUEUE</code>).</p>
		367	<p>It scales in the same way as the epoll backend, but the interface to the
		368	kernel is more efficient (which says nothing about its actual speed, of
		369	course). While starting and stopping an I/O watcher does not cause an
		370	extra syscall as with epoll, it still adds up to four event changes per
		371	incident, so its best to avoid that.</p>
		372	</dd>
		373	<dt><code>EVBACKEND_DEVPOLL</code> (value 16, Solaris 8)</dt>
		374	<dd>
		375	<p>This is not implemented yet (and might never be).</p>
		376	</dd>
		377	<dt><code>EVBACKEND_PORT</code> (value 32, Solaris 10)</dt>
		378	<dd>
		379	<p>This uses the Solaris 10 port mechanism. As with everything on Solaris,
		380	it's really slow, but it still scales very well (O(active_fds)).</p>
		381	<p>Please note that solaris ports can result in a lot of spurious
		382	notifications, so you need to use non-blocking I/O or other means to avoid
		383	blocking when no data (or space) is available.</p>
		384	</dd>
		385	<dt><code>EVBACKEND_ALL</code></dt>
		386	<dd>
		387	<p>Try all backends (even potentially broken ones that wouldn't be tried
		388	with <code>EVFLAG_AUTO</code>). Since this is a mask, you can do stuff such as
		389	<code>EVBACKEND_ALL & ~EVBACKEND_KQUEUE</code>.</p>
190	</dd>	390	</dd>
191	</dl>	391	</dl>
192	</p>	392	</p>
		393	<p>If one or more of these are ored into the flags value, then only these
		394	backends will be tried (in the reverse order as given here). If none are
		395	specified, most compiled-in backend will be tried, usually in reverse
		396	order of their flag values :)</p>
		397	<p>The most typical usage is like this:</p>
		398	<pre> if (!ev_default_loop (0))
		399	fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?");
		400
		401	</pre>
		402	<p>Restrict libev to the select and poll backends, and do not allow
		403	environment settings to be taken into account:</p>
		404	<pre> ev_default_loop (EVBACKEND_POLL \| EVBACKEND_SELECT \| EVFLAG_NOENV);
		405
		406	</pre>
		407	<p>Use whatever libev has to offer, but make sure that kqueue is used if
		408	available (warning, breaks stuff, best use only with your own private
		409	event loop and only if you know the OS supports your types of fds):</p>
		410	<pre> ev_default_loop (ev_recommended_backends () \| EVBACKEND_KQUEUE);
		411
		412	</pre>
193	</dd>	413	</dd>
194	<dt>struct ev_loop *ev_loop_new (unsigned int flags)</dt>	414	<dt>struct ev_loop *ev_loop_new (unsigned int flags)</dt>
195	<dd>	415	<dd>
196	<p>Similar to <code>ev_default_loop</code>, but always creates a new event loop that is	416	<p>Similar to <code>ev_default_loop</code>, but always creates a new event loop that is
197	always distinct from the default loop. Unlike the default loop, it cannot	417	always distinct from the default loop. Unlike the default loop, it cannot
198	handle signal and child watchers, and attempts to do so will be greeted by	418	handle signal and child watchers, and attempts to do so will be greeted by
199	undefined behaviour (or a failed assertion if assertions are enabled).</p>	419	undefined behaviour (or a failed assertion if assertions are enabled).</p>
		420	<p>Example: Try to create a event loop that uses epoll and nothing else.</p>
		421	<pre> struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL \| EVFLAG_NOENV);
		422	if (!epoller)
		423	fatal ("no epoll found here, maybe it hides under your chair");
		424
		425	</pre>
200	</dd>	426	</dd>
201	<dt>ev_default_destroy ()</dt>	427	<dt>ev_default_destroy ()</dt>
202	<dd>	428	<dd>
203	<p>Destroys the default loop again (frees all memory and kernel state	429	<p>Destroys the default loop again (frees all memory and kernel state
204	etc.). This stops all registered event watchers (by not touching them in	430	etc.). None of the active event watchers will be stopped in the normal
205	any way whatsoever, although you cannot rely on this :).</p>	431	sense, so e.g. <code>ev_is_active</code> might still return true. It is your
		432	responsibility to either stop all watchers cleanly yoursef <i>before</i>
		433	calling this function, or cope with the fact afterwards (which is usually
		434	the easiest thing, youc na just ignore the watchers and/or <code>free ()</code> them
		435	for example).</p>
206	</dd>	436	</dd>
207	<dt>ev_loop_destroy (loop)</dt>	437	<dt>ev_loop_destroy (loop)</dt>
208	<dd>	438	<dd>
209	<p>Like <code>ev_default_destroy</code>, but destroys an event loop created by an	439	<p>Like <code>ev_default_destroy</code>, but destroys an event loop created by an
210	earlier call to <code>ev_loop_new</code>.</p>	440	earlier call to <code>ev_loop_new</code>.</p>
…		…
213	<dd>	443	<dd>
214	<p>This function reinitialises the kernel state for backends that have	444	<p>This function reinitialises the kernel state for backends that have
215	one. Despite the name, you can call it anytime, but it makes most sense	445	one. Despite the name, you can call it anytime, but it makes most sense
216	after forking, in either the parent or child process (or both, but that	446	after forking, in either the parent or child process (or both, but that
217	again makes little sense).</p>	447	again makes little sense).</p>
218	<p>You <i>must</i> call this function after forking if and only if you want to	448	<p>You <i>must</i> call this function in the child process after forking if and
219	use the event library in both processes. If you just fork+exec, you don't	449	only if you want to use the event library in both processes. If you just
220	have to call it.</p>	450	fork+exec, you don't have to call it.</p>
221	<p>The function itself is quite fast and it's usually not a problem to call	451	<p>The function itself is quite fast and it's usually not a problem to call
222	it just in case after a fork. To make this easy, the function will fit in	452	it just in case after a fork. To make this easy, the function will fit in
223	quite nicely into a call to <code>pthread_atfork</code>:</p>	453	quite nicely into a call to <code>pthread_atfork</code>:</p>
224	<pre> pthread_atfork (0, 0, ev_default_fork);	454	<pre> pthread_atfork (0, 0, ev_default_fork);
225		455
226	</pre>	456	</pre>
		457	<p>At the moment, <code>EVBACKEND_SELECT</code> and <code>EVBACKEND_POLL</code> are safe to use
		458	without calling this function, so if you force one of those backends you
		459	do not need to care.</p>
227	</dd>	460	</dd>
228	<dt>ev_loop_fork (loop)</dt>	461	<dt>ev_loop_fork (loop)</dt>
229	<dd>	462	<dd>
230	<p>Like <code>ev_default_fork</code>, but acts on an event loop created by	463	<p>Like <code>ev_default_fork</code>, but acts on an event loop created by
231	<code>ev_loop_new</code>. Yes, you have to call this on every allocated event loop	464	<code>ev_loop_new</code>. Yes, you have to call this on every allocated event loop
232	after fork, and how you do this is entirely your own problem.</p>	465	after fork, and how you do this is entirely your own problem.</p>
233	</dd>	466	</dd>
234	<dt>unsigned int ev_method (loop)</dt>	467	<dt>unsigned int ev_backend (loop)</dt>
235	<dd>	468	<dd>
236	<p>Returns one of the <code>EVMETHOD_*</code> flags indicating the event backend in	469	<p>Returns one of the <code>EVBACKEND_*</code> flags indicating the event backend in
237	use.</p>	470	use.</p>
238	</dd>	471	</dd>
239	<dt>ev_tstamp ev_now (loop)</dt>	472	<dt>ev_tstamp ev_now (loop)</dt>
240	<dd>	473	<dd>
241	<p>Returns the current "event loop time", which is the time the event loop	474	<p>Returns the current "event loop time", which is the time the event loop
242	got events and started processing them. This timestamp does not change	475	received events and started processing them. This timestamp does not
243	as long as callbacks are being processed, and this is also the base time	476	change as long as callbacks are being processed, and this is also the base
244	used for relative timers. You can treat it as the timestamp of the event	477	time used for relative timers. You can treat it as the timestamp of the
245	occuring (or more correctly, the mainloop finding out about it).</p>	478	event occuring (or more correctly, libev finding out about it).</p>
246	</dd>	479	</dd>
247	<dt>ev_loop (loop, int flags)</dt>	480	<dt>ev_loop (loop, int flags)</dt>
248	<dd>	481	<dd>
249	<p>Finally, this is it, the event handler. This function usually is called	482	<p>Finally, this is it, the event handler. This function usually is called
250	after you initialised all your watchers and you want to start handling	483	after you initialised all your watchers and you want to start handling
251	events.</p>	484	events.</p>
252	<p>If the flags argument is specified as 0, it will not return until either	485	<p>If the flags argument is specified as <code>0</code>, it will not return until
253	no event watchers are active anymore or <code>ev_unloop</code> was called.</p>	486	either no event watchers are active anymore or <code>ev_unloop</code> was called.</p>
		487	<p>Please note that an explicit <code>ev_unloop</code> is usually better than
		488	relying on all watchers to be stopped when deciding when a program has
		489	finished (especially in interactive programs), but having a program that
		490	automatically loops as long as it has to and no longer by virtue of
		491	relying on its watchers stopping correctly is a thing of beauty.</p>
254	<p>A flags value of <code>EVLOOP_NONBLOCK</code> will look for new events, will handle	492	<p>A flags value of <code>EVLOOP_NONBLOCK</code> will look for new events, will handle
255	those events and any outstanding ones, but will not block your process in	493	those events and any outstanding ones, but will not block your process in
256	case there are no events and will return after one iteration of the loop.</p>	494	case there are no events and will return after one iteration of the loop.</p>
257	<p>A flags value of <code>EVLOOP_ONESHOT</code> will look for new events (waiting if	495	<p>A flags value of <code>EVLOOP_ONESHOT</code> will look for new events (waiting if
258	neccessary) and will handle those and any outstanding ones. It will block	496	neccessary) and will handle those and any outstanding ones. It will block
259	your process until at least one new event arrives, and will return after	497	your process until at least one new event arrives, and will return after
260	one iteration of the loop.</p>	498	one iteration of the loop. This is useful if you are waiting for some
261	<p>This flags value could be used to implement alternative looping	499	external event in conjunction with something not expressible using other
262	constructs, but the <code>prepare</code> and <code>check</code> watchers provide a better and	500	libev watchers. However, a pair of <code>ev_prepare</code>/<code>ev_check</code> watchers is
263	more generic mechanism.</p>	501	usually a better approach for this kind of thing.</p>
		502	<p>Here are the gory details of what <code>ev_loop</code> does:</p>
		503	<pre> * If there are no active watchers (reference count is zero), return.
		504	- Queue prepare watchers and then call all outstanding watchers.
		505	- If we have been forked, recreate the kernel state.
		506	- Update the kernel state with all outstanding changes.
		507	- Update the "event loop time".
		508	- Calculate for how long to block.
		509	- Block the process, waiting for any events.
		510	- Queue all outstanding I/O (fd) events.
		511	- Update the "event loop time" and do time jump handling.
		512	- Queue all outstanding timers.
		513	- Queue all outstanding periodics.
		514	- If no events are pending now, queue all idle watchers.
		515	- Queue all check watchers.
		516	- Call all queued watchers in reverse order (i.e. check watchers first).
		517	Signals and child watchers are implemented as I/O watchers, and will
		518	be handled here by queueing them when their watcher gets executed.
		519	- If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK
		520	were used, return, otherwise continue with step *.
		521
		522	</pre>
		523	<p>Example: Queue some jobs and then loop until no events are outsanding
		524	anymore.</p>
		525	<pre> ... queue jobs here, make sure they register event watchers as long
		526	... as they still have work to do (even an idle watcher will do..)
		527	ev_loop (my_loop, 0);
		528	... jobs done. yeah!
		529
		530	</pre>
264	</dd>	531	</dd>
265	<dt>ev_unloop (loop, how)</dt>	532	<dt>ev_unloop (loop, how)</dt>
266	<dd>	533	<dd>
267	<p>Can be used to make a call to <code>ev_loop</code> return early (but only after it	534	<p>Can be used to make a call to <code>ev_loop</code> return early (but only after it
268	has processed all outstanding events). The <code>how</code> argument must be either	535	has processed all outstanding events). The <code>how</code> argument must be either
269	<code>EVUNLOOP_ONCE</code>, which will make the innermost <code>ev_loop</code> call return, or	536	<code>EVUNLOOP_ONE</code>, which will make the innermost <code>ev_loop</code> call return, or
270	<code>EVUNLOOP_ALL</code>, which will make all nested <code>ev_loop</code> calls return.</p>	537	<code>EVUNLOOP_ALL</code>, which will make all nested <code>ev_loop</code> calls return.</p>
271	</dd>	538	</dd>
272	<dt>ev_ref (loop)</dt>	539	<dt>ev_ref (loop)</dt>
273	<dt>ev_unref (loop)</dt>	540	<dt>ev_unref (loop)</dt>
274	<dd>	541	<dd>
…		…
280	example, libev itself uses this for its internal signal pipe: It is not	547	example, libev itself uses this for its internal signal pipe: It is not
281	visible to the libev user and should not keep <code>ev_loop</code> from exiting if	548	visible to the libev user and should not keep <code>ev_loop</code> from exiting if
282	no event watchers registered by it are active. It is also an excellent	549	no event watchers registered by it are active. It is also an excellent
283	way to do this for generic recurring timers or from within third-party	550	way to do this for generic recurring timers or from within third-party
284	libraries. Just remember to <i>unref after start</i> and <i>ref before stop</i>.</p>	551	libraries. Just remember to <i>unref after start</i> and <i>ref before stop</i>.</p>
		552	<p>Example: Create a signal watcher, but keep it from keeping <code>ev_loop</code>
		553	running when nothing else is active.</p>
		554	<pre> struct ev_signal exitsig;
		555	ev_signal_init (&exitsig, sig_cb, SIGINT);
		556	ev_signal_start (loop, &exitsig);
		557	evf_unref (loop);
		558
		559	</pre>
		560	<p>Example: For some weird reason, unregister the above signal handler again.</p>
		561	<pre> ev_ref (loop);
		562	ev_signal_stop (loop, &exitsig);
		563
		564	</pre>
285	</dd>	565	</dd>
286	</dl>	566	</dl>
287		567
		568
		569
		570
		571
288	</div>	572	</div>
289	<h1 id="ANATOMY_OF_A_WATCHER">ANATOMY OF A WATCHER</h1><p><a href="#TOP" class="toplink">Top</a></p>	573	<h1 id="ANATOMY_OF_A_WATCHER">ANATOMY OF A WATCHER</h1>
290	<div id="ANATOMY_OF_A_WATCHER_CONTENT">	574	<div id="ANATOMY_OF_A_WATCHER_CONTENT">
291	<p>A watcher is a structure that you create and register to record your	575	<p>A watcher is a structure that you create and register to record your
292	interest in some event. For instance, if you want to wait for STDIN to	576	interest in some event. For instance, if you want to wait for STDIN to
293	become readable, you would create an <code>ev_io</code> watcher for that:</p>	577	become readable, you would create an <code>ev_io</code> watcher for that:</p>
294	<pre> static void my_cb (struct ev_loop loop, struct ev_io w, int revents)	578	<pre> static void my_cb (struct ev_loop loop, struct ev_io w, int revents)
…		…
321	with a watcher-specific start function (<code>ev_<type>_start (loop, watcher	605	with a watcher-specific start function (<code>ev_<type>_start (loop, watcher
322	*)</code>), and you can stop watching for events at any time by calling the	606	*)</code>), and you can stop watching for events at any time by calling the
323	corresponding stop function (<code>ev_<type>_stop (loop, watcher *)</code>.</p>	607	corresponding stop function (<code>ev_<type>_stop (loop, watcher *)</code>.</p>
324	<p>As long as your watcher is active (has been started but not stopped) you	608	<p>As long as your watcher is active (has been started but not stopped) you
325	must not touch the values stored in it. Most specifically you must never	609	must not touch the values stored in it. Most specifically you must never
326	reinitialise it or call its set method.</p>	610	reinitialise it or call its <code>set</code> macro.</p>
327	<p>You cna check whether an event is active by calling the <code>ev_is_active
328	(watcher *)</code> macro. To see whether an event is outstanding (but the
329	callback for it has not been called yet) you cna use the <code>ev_is_pending
330	(watcher *)</code> macro.</p>
331	<p>Each and every callback receives the event loop pointer as first, the	611	<p>Each and every callback receives the event loop pointer as first, the
332	registered watcher structure as second, and a bitset of received events as	612	registered watcher structure as second, and a bitset of received events as
333	third argument.</p>	613	third argument.</p>
334	<p>The rceeived events usually include a single bit per event type received	614	<p>The received events usually include a single bit per event type received
335	(you can receive multiple events at the same time). The possible bit masks	615	(you can receive multiple events at the same time). The possible bit masks
336	are:</p>	616	are:</p>
337	<dl>	617	<dl>
338	<dt><code>EV_READ</code></dt>	618	<dt><code>EV_READ</code></dt>
339	<dt><code>EV_WRITE</code></dt>	619	<dt><code>EV_WRITE</code></dt>
…		…
354	<p>The signal specified in the <code>ev_signal</code> watcher has been received by a thread.</p>	634	<p>The signal specified in the <code>ev_signal</code> watcher has been received by a thread.</p>
355	</dd>	635	</dd>
356	<dt><code>EV_CHILD</code></dt>	636	<dt><code>EV_CHILD</code></dt>
357	<dd>	637	<dd>
358	<p>The pid specified in the <code>ev_child</code> watcher has received a status change.</p>	638	<p>The pid specified in the <code>ev_child</code> watcher has received a status change.</p>
		639	</dd>
		640	<dt><code>EV_STAT</code></dt>
		641	<dd>
		642	<p>The path specified in the <code>ev_stat</code> watcher changed its attributes somehow.</p>
359	</dd>	643	</dd>
360	<dt><code>EV_IDLE</code></dt>	644	<dt><code>EV_IDLE</code></dt>
361	<dd>	645	<dd>
362	<p>The <code>ev_idle</code> watcher has determined that you have nothing better to do.</p>	646	<p>The <code>ev_idle</code> watcher has determined that you have nothing better to do.</p>
363	</dd>	647	</dd>
…		…
369	<code>ev_loop</code> has gathered them, but before it invokes any callbacks for any	653	<code>ev_loop</code> has gathered them, but before it invokes any callbacks for any
370	received events. Callbacks of both watcher types can start and stop as	654	received events. Callbacks of both watcher types can start and stop as
371	many watchers as they want, and all of them will be taken into account	655	many watchers as they want, and all of them will be taken into account
372	(for example, a <code>ev_prepare</code> watcher might start an idle watcher to keep	656	(for example, a <code>ev_prepare</code> watcher might start an idle watcher to keep
373	<code>ev_loop</code> from blocking).</p>	657	<code>ev_loop</code> from blocking).</p>
		658	</dd>
		659	<dt><code>EV_EMBED</code></dt>
		660	<dd>
		661	<p>The embedded event loop specified in the <code>ev_embed</code> watcher needs attention.</p>
		662	</dd>
		663	<dt><code>EV_FORK</code></dt>
		664	<dd>
		665	<p>The event loop has been resumed in the child process after fork (see
		666	<code>ev_fork</code>).</p>
374	</dd>	667	</dd>
375	<dt><code>EV_ERROR</code></dt>	668	<dt><code>EV_ERROR</code></dt>
376	<dd>	669	<dd>
377	<p>An unspecified error has occured, the watcher has been stopped. This might	670	<p>An unspecified error has occured, the watcher has been stopped. This might
378	happen because the watcher could not be properly started because libev	671	happen because the watcher could not be properly started because libev
…		…
386	programs, though, so beware.</p>	679	programs, though, so beware.</p>
387	</dd>	680	</dd>
388	</dl>	681	</dl>
389		682
390	</div>	683	</div>
		684	<h2 id="GENERIC_WATCHER_FUNCTIONS">GENERIC WATCHER FUNCTIONS</h2>
		685	<div id="GENERIC_WATCHER_FUNCTIONS_CONTENT">
		686	<p>In the following description, <code>TYPE</code> stands for the watcher type,
		687	e.g. <code>timer</code> for <code>ev_timer</code> watchers and <code>io</code> for <code>ev_io</code> watchers.</p>
		688	<dl>
		689	<dt><code>ev_init</code> (ev_TYPE *watcher, callback)</dt>
		690	<dd>
		691	<p>This macro initialises the generic portion of a watcher. The contents
		692	of the watcher object can be arbitrary (so <code>malloc</code> will do). Only
		693	the generic parts of the watcher are initialised, you <i>need</i> to call
		694	the type-specific <code>ev_TYPE_set</code> macro afterwards to initialise the
		695	type-specific parts. For each type there is also a <code>ev_TYPE_init</code> macro
		696	which rolls both calls into one.</p>
		697	<p>You can reinitialise a watcher at any time as long as it has been stopped
		698	(or never started) and there are no pending events outstanding.</p>
		699	<p>The callback is always of type <code>void ()(ev_loop loop, ev_TYPE *watcher,
		700	int revents)</code>.</p>
		701	</dd>
		702	<dt><code>ev_TYPE_set</code> (ev_TYPE *, [args])</dt>
		703	<dd>
		704	<p>This macro initialises the type-specific parts of a watcher. You need to
		705	call <code>ev_init</code> at least once before you call this macro, but you can
		706	call <code>ev_TYPE_set</code> any number of times. You must not, however, call this
		707	macro on a watcher that is active (it can be pending, however, which is a
		708	difference to the <code>ev_init</code> macro).</p>
		709	<p>Although some watcher types do not have type-specific arguments
		710	(e.g. <code>ev_prepare</code>) you still need to call its <code>set</code> macro.</p>
		711	</dd>
		712	<dt><code>ev_TYPE_init</code> (ev_TYPE *watcher, callback, [args])</dt>
		713	<dd>
		714	<p>This convinience macro rolls both <code>ev_init</code> and <code>ev_TYPE_set</code> macro
		715	calls into a single call. This is the most convinient method to initialise
		716	a watcher. The same limitations apply, of course.</p>
		717	</dd>
		718	<dt><code>ev_TYPE_start</code> (loop , ev_TYPE watcher)</dt>
		719	<dd>
		720	<p>Starts (activates) the given watcher. Only active watchers will receive
		721	events. If the watcher is already active nothing will happen.</p>
		722	</dd>
		723	<dt><code>ev_TYPE_stop</code> (loop , ev_TYPE watcher)</dt>
		724	<dd>
		725	<p>Stops the given watcher again (if active) and clears the pending
		726	status. It is possible that stopped watchers are pending (for example,
		727	non-repeating timers are being stopped when they become pending), but
		728	<code>ev_TYPE_stop</code> ensures that the watcher is neither active nor pending. If
		729	you want to free or reuse the memory used by the watcher it is therefore a
		730	good idea to always call its <code>ev_TYPE_stop</code> function.</p>
		731	</dd>
		732	<dt>bool ev_is_active (ev_TYPE *watcher)</dt>
		733	<dd>
		734	<p>Returns a true value iff the watcher is active (i.e. it has been started
		735	and not yet been stopped). As long as a watcher is active you must not modify
		736	it.</p>
		737	</dd>
		738	<dt>bool ev_is_pending (ev_TYPE *watcher)</dt>
		739	<dd>
		740	<p>Returns a true value iff the watcher is pending, (i.e. it has outstanding
		741	events but its callback has not yet been invoked). As long as a watcher
		742	is pending (but not active) you must not call an init function on it (but
		743	<code>ev_TYPE_set</code> is safe) and you must make sure the watcher is available to
		744	libev (e.g. you cnanot <code>free ()</code> it).</p>
		745	</dd>
		746	<dt>callback ev_cb (ev_TYPE *watcher)</dt>
		747	<dd>
		748	<p>Returns the callback currently set on the watcher.</p>
		749	</dd>
		750	<dt>ev_cb_set (ev_TYPE *watcher, callback)</dt>
		751	<dd>
		752	<p>Change the callback. You can change the callback at virtually any time
		753	(modulo threads).</p>
		754	</dd>
		755	</dl>
		756
		757
		758
		759
		760
		761	</div>
391	<h2 id="ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH">ASSOCIATING CUSTOM DATA WITH A WATCHER</h2>	762	<h2 id="ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH">ASSOCIATING CUSTOM DATA WITH A WATCHER</h2>
392	<div id="ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH-2">	763	<div id="ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH-2">
393	<p>Each watcher has, by default, a member <code>void *data</code> that you can change	764	<p>Each watcher has, by default, a member <code>void *data</code> that you can change
394	and read at any time, libev will completely ignore it. This cna be used	765	and read at any time, libev will completely ignore it. This can be used
395	to associate arbitrary data with your watcher. If you need more data and	766	to associate arbitrary data with your watcher. If you need more data and
396	don't want to allocate memory and store a pointer to it in that data	767	don't want to allocate memory and store a pointer to it in that data
397	member, you can also "subclass" the watcher type and provide your own	768	member, you can also "subclass" the watcher type and provide your own
398	data:</p>	769	data:</p>
399	<pre> struct my_io	770	<pre> struct my_io
…		…
412	struct my_io w = (struct my_io )w_;	783	struct my_io w = (struct my_io )w_;
413	...	784	...
414	}	785	}
415		786
416	</pre>	787	</pre>
417	<p>More interesting and less C-conformant ways of catsing your callback type	788	<p>More interesting and less C-conformant ways of casting your callback type
418	have been omitted....</p>	789	instead have been omitted.</p>
		790	<p>Another common scenario is having some data structure with multiple
		791	watchers:</p>
		792	<pre> struct my_biggy
		793	{
		794	int some_data;
		795	ev_timer t1;
		796	ev_timer t2;
		797	}
419		798
		799	</pre>
		800	<p>In this case getting the pointer to <code>my_biggy</code> is a bit more complicated,
		801	you need to use <code>offsetof</code>:</p>
		802	<pre> #include <stddef.h>
420		803
		804	static void
		805	t1_cb (EV_P_ struct ev_timer *w, int revents)
		806	{
		807	struct my_biggy big = (struct my_biggy *
		808	(((char *)w) - offsetof (struct my_biggy, t1));
		809	}
421		810
		811	static void
		812	t2_cb (EV_P_ struct ev_timer *w, int revents)
		813	{
		814	struct my_biggy big = (struct my_biggy *
		815	(((char *)w) - offsetof (struct my_biggy, t2));
		816	}
422		817
423		818
		819
		820
		821	</pre>
		822
424	</div>	823	</div>
425	<h1 id="WATCHER_TYPES">WATCHER TYPES</h1><p><a href="#TOP" class="toplink">Top</a></p>	824	<h1 id="WATCHER_TYPES">WATCHER TYPES</h1>
426	<div id="WATCHER_TYPES_CONTENT">	825	<div id="WATCHER_TYPES_CONTENT">
427	<p>This section describes each watcher in detail, but will not repeat	826	<p>This section describes each watcher in detail, but will not repeat
428	information given in the last section.</p>	827	information given in the last section. Any initialisation/set macros,
		828	functions and members specific to the watcher type are explained.</p>
		829	<p>Members are additionally marked with either <i>[read-only]</i>, meaning that,
		830	while the watcher is active, you can look at the member and expect some
		831	sensible content, but you must not modify it (you can modify it while the
		832	watcher is stopped to your hearts content), or <i>[read-write]</i>, which
		833	means you can expect it to have some sensible content while the watcher
		834	is active, but you can also modify it. Modifying it may not do something
		835	sensible or take immediate effect (or do anything at all), but libev will
		836	not crash or malfunction in any way.</p>
429		837
		838
		839
		840
		841
430	</div>	842	</div>
431	<h2 id="code_ev_io_code_is_this_file_descrip"><code>ev_io</code> - is this file descriptor readable or writable</h2>	843	<h2 id="code_ev_io_code_is_this_file_descrip"><code>ev_io</code> - is this file descriptor readable or writable?</h2>
432	<div id="code_ev_io_code_is_this_file_descrip-2">	844	<div id="code_ev_io_code_is_this_file_descrip-2">
433	<p>I/O watchers check whether a file descriptor is readable or writable	845	<p>I/O watchers check whether a file descriptor is readable or writable
434	in each iteration of the event loop (This behaviour is called	846	in each iteration of the event loop, or, more precisely, when reading
435	level-triggering because you keep receiving events as long as the	847	would not block the process and writing would at least be able to write
436	condition persists. Remember you cna stop the watcher if you don't want to	848	some data. This behaviour is called level-triggering because you keep
437	act on the event and neither want to receive future events).</p>	849	receiving events as long as the condition persists. Remember you can stop
		850	the watcher if you don't want to act on the event and neither want to
		851	receive future events.</p>
438	<p>In general you can register as many read and/or write event watchers oer	852	<p>In general you can register as many read and/or write event watchers per
439	fd as you want (as long as you don't confuse yourself). Setting all file	853	fd as you want (as long as you don't confuse yourself). Setting all file
440	descriptors to non-blocking mode is also usually a good idea (but not	854	descriptors to non-blocking mode is also usually a good idea (but not
441	required if you know what you are doing).</p>	855	required if you know what you are doing).</p>
442	<p>You have to be careful with dup'ed file descriptors, though. Some backends	856	<p>You have to be careful with dup'ed file descriptors, though. Some backends
443	(the linux epoll backend is a notable example) cannot handle dup'ed file	857	(the linux epoll backend is a notable example) cannot handle dup'ed file
444	descriptors correctly if you register interest in two or more fds pointing	858	descriptors correctly if you register interest in two or more fds pointing
445	to the same file/socket etc. description.</p>	859	to the same underlying file/socket/etc. description (that is, they share
		860	the same underlying "file open").</p>
446	<p>If you must do this, then force the use of a known-to-be-good backend	861	<p>If you must do this, then force the use of a known-to-be-good backend
447	(at the time of this writing, this includes only EVMETHOD_SELECT and	862	(at the time of this writing, this includes only <code>EVBACKEND_SELECT</code> and
448	EVMETHOD_POLL).</p>	863	<code>EVBACKEND_POLL</code>).</p>
		864	<p>Another thing you have to watch out for is that it is quite easy to
		865	receive "spurious" readyness notifications, that is your callback might
		866	be called with <code>EV_READ</code> but a subsequent <code>read</code>(2) will actually block
		867	because there is no data. Not only are some backends known to create a
		868	lot of those (for example solaris ports), it is very easy to get into
		869	this situation even with a relatively standard program structure. Thus
		870	it is best to always use non-blocking I/O: An extra <code>read</code>(2) returning
		871	<code>EAGAIN</code> is far preferable to a program hanging until some data arrives.</p>
		872	<p>If you cannot run the fd in non-blocking mode (for example you should not
		873	play around with an Xlib connection), then you have to seperately re-test
		874	wether a file descriptor is really ready with a known-to-be good interface
		875	such as poll (fortunately in our Xlib example, Xlib already does this on
		876	its own, so its quite safe to use).</p>
449	<dl>	877	<dl>
450	<dt>ev_io_init (ev_io *, callback, int fd, int events)</dt>	878	<dt>ev_io_init (ev_io *, callback, int fd, int events)</dt>
451	<dt>ev_io_set (ev_io *, int fd, int events)</dt>	879	<dt>ev_io_set (ev_io *, int fd, int events)</dt>
452	<dd>	880	<dd>
453	<p>Configures an <code>ev_io</code> watcher. The fd is the file descriptor to rceeive	881	<p>Configures an <code>ev_io</code> watcher. The <code>fd</code> is the file descriptor to
454	events for and events is either <code>EV_READ</code>, <code>EV_WRITE</code> or <code>EV_READ \|	882	rceeive events for and events is either <code>EV_READ</code>, <code>EV_WRITE</code> or
455	EV_WRITE</code> to receive the given events.</p>	883	<code>EV_READ \| EV_WRITE</code> to receive the given events.</p>
		884	</dd>
		885	<dt>int fd [read-only]</dt>
		886	<dd>
		887	<p>The file descriptor being watched.</p>
		888	</dd>
		889	<dt>int events [read-only]</dt>
		890	<dd>
		891	<p>The events being watched.</p>
456	</dd>	892	</dd>
457	</dl>	893	</dl>
		894	<p>Example: Call <code>stdin_readable_cb</code> when STDIN_FILENO has become, well
		895	readable, but only once. Since it is likely line-buffered, you could
		896	attempt to read a whole line in the callback.</p>
		897	<pre> static void
		898	stdin_readable_cb (struct ev_loop loop, struct ev_io w, int revents)
		899	{
		900	ev_io_stop (loop, w);
		901	.. read from stdin here (or from w->fd) and haqndle any I/O errors
		902	}
458		903
		904	...
		905	struct ev_loop *loop = ev_default_init (0);
		906	struct ev_io stdin_readable;
		907	ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);
		908	ev_io_start (loop, &stdin_readable);
		909	ev_loop (loop, 0);
		910
		911
		912
		913
		914	</pre>
		915
459	</div>	916	</div>
460	<h2 id="code_ev_timer_code_relative_and_opti"><code>ev_timer</code> - relative and optionally recurring timeouts</h2>	917	<h2 id="code_ev_timer_code_relative_and_opti"><code>ev_timer</code> - relative and optionally repeating timeouts</h2>
461	<div id="code_ev_timer_code_relative_and_opti-2">	918	<div id="code_ev_timer_code_relative_and_opti-2">
462	<p>Timer watchers are simple relative timers that generate an event after a	919	<p>Timer watchers are simple relative timers that generate an event after a
463	given time, and optionally repeating in regular intervals after that.</p>	920	given time, and optionally repeating in regular intervals after that.</p>
464	<p>The timers are based on real time, that is, if you register an event that	921	<p>The timers are based on real time, that is, if you register an event that
465	times out after an hour and youreset your system clock to last years	922	times out after an hour and you reset your system clock to last years
466	time, it will still time out after (roughly) and hour. "Roughly" because	923	time, it will still time out after (roughly) and hour. "Roughly" because
467	detecting time jumps is hard, and soem inaccuracies are unavoidable (the	924	detecting time jumps is hard, and some inaccuracies are unavoidable (the
468	monotonic clock option helps a lot here).</p>	925	monotonic clock option helps a lot here).</p>
469	<p>The relative timeouts are calculated relative to the <code>ev_now ()</code>	926	<p>The relative timeouts are calculated relative to the <code>ev_now ()</code>
470	time. This is usually the right thing as this timestamp refers to the time	927	time. This is usually the right thing as this timestamp refers to the time
471	of the event triggering whatever timeout you are modifying/starting. If	928	of the event triggering whatever timeout you are modifying/starting. If
472	you suspect event processing to be delayed and you need to base the timeout	929	you suspect event processing to be delayed and you <i>need</i> to base the timeout
473	ion the current time, use something like this to adjust for this:</p>	930	on the current time, use something like this to adjust for this:</p>
474	<pre> ev_timer_set (&timer, after + ev_now () - ev_time (), 0.);	931	<pre> ev_timer_set (&timer, after + ev_now () - ev_time (), 0.);
475		932
476	</pre>	933	</pre>
		934	<p>The callback is guarenteed to be invoked only when its timeout has passed,
		935	but if multiple timers become ready during the same loop iteration then
		936	order of execution is undefined.</p>
477	<dl>	937	<dl>
478	<dt>ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)</dt>	938	<dt>ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)</dt>
479	<dt>ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)</dt>	939	<dt>ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)</dt>
480	<dd>	940	<dd>
481	<p>Configure the timer to trigger after <code>after</code> seconds. If <code>repeat</code> is	941	<p>Configure the timer to trigger after <code>after</code> seconds. If <code>repeat</code> is
…		…
483	timer will automatically be configured to trigger again <code>repeat</code> seconds	943	timer will automatically be configured to trigger again <code>repeat</code> seconds
484	later, again, and again, until stopped manually.</p>	944	later, again, and again, until stopped manually.</p>
485	<p>The timer itself will do a best-effort at avoiding drift, that is, if you	945	<p>The timer itself will do a best-effort at avoiding drift, that is, if you
486	configure a timer to trigger every 10 seconds, then it will trigger at	946	configure a timer to trigger every 10 seconds, then it will trigger at
487	exactly 10 second intervals. If, however, your program cannot keep up with	947	exactly 10 second intervals. If, however, your program cannot keep up with
488	the timer (ecause it takes longer than those 10 seconds to do stuff) the	948	the timer (because it takes longer than those 10 seconds to do stuff) the
489	timer will not fire more than once per event loop iteration.</p>	949	timer will not fire more than once per event loop iteration.</p>
490	</dd>	950	</dd>
491	<dt>ev_timer_again (loop)</dt>	951	<dt>ev_timer_again (loop)</dt>
492	<dd>	952	<dd>
493	<p>This will act as if the timer timed out and restart it again if it is	953	<p>This will act as if the timer timed out and restart it again if it is
494	repeating. The exact semantics are:</p>	954	repeating. The exact semantics are:</p>
495	<p>If the timer is started but nonrepeating, stop it.</p>	955	<p>If the timer is started but nonrepeating, stop it.</p>
496	<p>If the timer is repeating, either start it if necessary (with the repeat	956	<p>If the timer is repeating, either start it if necessary (with the repeat
497	value), or reset the running timer to the repeat value.</p>	957	value), or reset the running timer to the repeat value.</p>
498	<p>This sounds a bit complicated, but here is a useful and typical	958	<p>This sounds a bit complicated, but here is a useful and typical
499	example: Imagine you have a tcp connection and you want a so-called idle	959	example: Imagine you have a tcp connection and you want a so-called
500	timeout, that is, you want to be called when there have been, say, 60	960	idle timeout, that is, you want to be called when there have been,
501	seconds of inactivity on the socket. The easiest way to do this is to	961	say, 60 seconds of inactivity on the socket. The easiest way to do
502	configure an <code>ev_timer</code> with after=repeat=60 and calling ev_timer_again each	962	this is to configure an <code>ev_timer</code> with <code>after</code>=<code>repeat</code>=<code>60</code> and calling
503	time you successfully read or write some data. If you go into an idle	963	<code>ev_timer_again</code> each time you successfully read or write some data. If
504	state where you do not expect data to travel on the socket, you can stop	964	you go into an idle state where you do not expect data to travel on the
505	the timer, and again will automatically restart it if need be.</p>	965	socket, you can stop the timer, and again will automatically restart it if
		966	need be.</p>
		967	<p>You can also ignore the <code>after</code> value and <code>ev_timer_start</code> altogether
		968	and only ever use the <code>repeat</code> value:</p>
		969	<pre> ev_timer_init (timer, callback, 0., 5.);
		970	ev_timer_again (loop, timer);
		971	...
		972	timer->again = 17.;
		973	ev_timer_again (loop, timer);
		974	...
		975	timer->again = 10.;
		976	ev_timer_again (loop, timer);
		977
		978	</pre>
		979	<p>This is more efficient then stopping/starting the timer eahc time you want
		980	to modify its timeout value.</p>
		981	</dd>
		982	<dt>ev_tstamp repeat [read-write]</dt>
		983	<dd>
		984	<p>The current <code>repeat</code> value. Will be used each time the watcher times out
		985	or <code>ev_timer_again</code> is called and determines the next timeout (if any),
		986	which is also when any modifications are taken into account.</p>
506	</dd>	987	</dd>
507	</dl>	988	</dl>
		989	<p>Example: Create a timer that fires after 60 seconds.</p>
		990	<pre> static void
		991	one_minute_cb (struct ev_loop loop, struct ev_timer w, int revents)
		992	{
		993	.. one minute over, w is actually stopped right here
		994	}
508		995
		996	struct ev_timer mytimer;
		997	ev_timer_init (&mytimer, one_minute_cb, 60., 0.);
		998	ev_timer_start (loop, &mytimer);
		999
		1000	</pre>
		1001	<p>Example: Create a timeout timer that times out after 10 seconds of
		1002	inactivity.</p>
		1003	<pre> static void
		1004	timeout_cb (struct ev_loop loop, struct ev_timer w, int revents)
		1005	{
		1006	.. ten seconds without any activity
		1007	}
		1008
		1009	struct ev_timer mytimer;
		1010	ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */
		1011	ev_timer_again (&mytimer); /* start timer */
		1012	ev_loop (loop, 0);
		1013
		1014	// and in some piece of code that gets executed on any "activity":
		1015	// reset the timeout to start ticking again at 10 seconds
		1016	ev_timer_again (&mytimer);
		1017
		1018
		1019
		1020
		1021	</pre>
		1022
509	</div>	1023	</div>
510	<h2 id="code_ev_periodic_code_to_cron_or_not"><code>ev_periodic</code> - to cron or not to cron it</h2>	1024	<h2 id="code_ev_periodic_code_to_cron_or_not"><code>ev_periodic</code> - to cron or not to cron?</h2>
511	<div id="code_ev_periodic_code_to_cron_or_not-2">	1025	<div id="code_ev_periodic_code_to_cron_or_not-2">
512	<p>Periodic watchers are also timers of a kind, but they are very versatile	1026	<p>Periodic watchers are also timers of a kind, but they are very versatile
513	(and unfortunately a bit complex).</p>	1027	(and unfortunately a bit complex).</p>
514	<p>Unlike <code>ev_timer</code>'s, they are not based on real time (or relative time)	1028	<p>Unlike <code>ev_timer</code>'s, they are not based on real time (or relative time)
515	but on wallclock time (absolute time). You can tell a periodic watcher	1029	but on wallclock time (absolute time). You can tell a periodic watcher
516	to trigger "at" some specific point in time. For example, if you tell a	1030	to trigger "at" some specific point in time. For example, if you tell a
517	periodic watcher to trigger in 10 seconds (by specifiying e.g. c<ev_now ()	1031	periodic watcher to trigger in 10 seconds (by specifiying e.g. <code>ev_now ()
518	+ 10.>) and then reset your system clock to the last year, then it will	1032	+ 10.</code>) and then reset your system clock to the last year, then it will
519	take a year to trigger the event (unlike an <code>ev_timer</code>, which would trigger	1033	take a year to trigger the event (unlike an <code>ev_timer</code>, which would trigger
520	roughly 10 seconds later and of course not if you reset your system time	1034	roughly 10 seconds later and of course not if you reset your system time
521	again).</p>	1035	again).</p>
522	<p>They can also be used to implement vastly more complex timers, such as	1036	<p>They can also be used to implement vastly more complex timers, such as
523	triggering an event on eahc midnight, local time.</p>	1037	triggering an event on eahc midnight, local time.</p>
		1038	<p>As with timers, the callback is guarenteed to be invoked only when the
		1039	time (<code>at</code>) has been passed, but if multiple periodic timers become ready
		1040	during the same loop iteration then order of execution is undefined.</p>
524	<dl>	1041	<dl>
525	<dt>ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)</dt>	1042	<dt>ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)</dt>
526	<dt>ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)</dt>	1043	<dt>ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)</dt>
527	<dd>	1044	<dd>
528	<p>Lots of arguments, lets sort it out... There are basically three modes of	1045	<p>Lots of arguments, lets sort it out... There are basically three modes of
529	operation, and we will explain them from simplest to complex:</p>	1046	operation, and we will explain them from simplest to complex:</p>
530
531
532
533
534	<p>	1047	<p>
535	<dl>	1048	<dl>
536	<dt>* absolute timer (interval = reschedule_cb = 0)</dt>	1049	<dt>* absolute timer (interval = reschedule_cb = 0)</dt>
537	<dd>	1050	<dd>
538	<p>In this configuration the watcher triggers an event at the wallclock time	1051	<p>In this configuration the watcher triggers an event at the wallclock time
…		…
562	<dd>	1075	<dd>
563	<p>In this mode the values for <code>interval</code> and <code>at</code> are both being	1076	<p>In this mode the values for <code>interval</code> and <code>at</code> are both being
564	ignored. Instead, each time the periodic watcher gets scheduled, the	1077	ignored. Instead, each time the periodic watcher gets scheduled, the
565	reschedule callback will be called with the watcher as first, and the	1078	reschedule callback will be called with the watcher as first, and the
566	current time as second argument.</p>	1079	current time as second argument.</p>
567	<p>NOTE: <i>This callback MUST NOT stop or destroy the periodic or any other	1080	<p>NOTE: <i>This callback MUST NOT stop or destroy any periodic watcher,
568	periodic watcher, ever, or make any event loop modifications</i>. If you need	1081	ever, or make any event loop modifications</i>. If you need to stop it,
569	to stop it, return <code>now + 1e30</code> (or so, fudge fudge) and stop it afterwards.</p>	1082	return <code>now + 1e30</code> (or so, fudge fudge) and stop it afterwards (e.g. by
570	<p>Also, <i><this callback must always return a time that is later than the	1083	starting a prepare watcher).</p>
571	passed <code>now</code> value </i>>. Not even <code>now</code> itself will be ok.</p>
572	<p>Its prototype is c<ev_tstamp (reschedule_cb)(struct ev_periodic w,	1084	<p>Its prototype is <code>ev_tstamp (reschedule_cb)(struct ev_periodic w,
573	ev_tstamp now)>, e.g.:</p>	1085	ev_tstamp now)</code>, e.g.:</p>
574	<pre> static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now)	1086	<pre> static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now)
575	{	1087	{
576	return now + 60.;	1088	return now + 60.;
577	}	1089	}
578		1090
579	</pre>	1091	</pre>
580	<p>It must return the next time to trigger, based on the passed time value	1092	<p>It must return the next time to trigger, based on the passed time value
581	(that is, the lowest time value larger than to the second argument). It	1093	(that is, the lowest time value larger than to the second argument). It
582	will usually be called just before the callback will be triggered, but	1094	will usually be called just before the callback will be triggered, but
583	might be called at other times, too.</p>	1095	might be called at other times, too.</p>
		1096	<p>NOTE: <i>This callback must always return a time that is later than the
		1097	passed <code>now</code> value</i>. Not even <code>now</code> itself will do, it <i>must</i> be larger.</p>
584	<p>This can be used to create very complex timers, such as a timer that	1098	<p>This can be used to create very complex timers, such as a timer that
585	triggers on each midnight, local time. To do this, you would calculate the	1099	triggers on each midnight, local time. To do this, you would calculate the
586	next midnight after <code>now</code> and return the timestamp value for this. How you do this	1100	next midnight after <code>now</code> and return the timestamp value for this. How
587	is, again, up to you (but it is not trivial).</p>	1101	you do this is, again, up to you (but it is not trivial, which is the main
		1102	reason I omitted it as an example).</p>
588	</dd>	1103	</dd>
589	</dl>	1104	</dl>
590	</p>	1105	</p>
591	</dd>	1106	</dd>
592	<dt>ev_periodic_again (loop, ev_periodic *)</dt>	1107	<dt>ev_periodic_again (loop, ev_periodic *)</dt>
…		…
594	<p>Simply stops and restarts the periodic watcher again. This is only useful	1109	<p>Simply stops and restarts the periodic watcher again. This is only useful
595	when you changed some parameters or the reschedule callback would return	1110	when you changed some parameters or the reschedule callback would return
596	a different time than the last time it was called (e.g. in a crond like	1111	a different time than the last time it was called (e.g. in a crond like
597	program when the crontabs have changed).</p>	1112	program when the crontabs have changed).</p>
598	</dd>	1113	</dd>
		1114	<dt>ev_tstamp interval [read-write]</dt>
		1115	<dd>
		1116	<p>The current interval value. Can be modified any time, but changes only
		1117	take effect when the periodic timer fires or <code>ev_periodic_again</code> is being
		1118	called.</p>
		1119	</dd>
		1120	<dt>ev_tstamp (reschedule_cb)(struct ev_periodic w, ev_tstamp now) [read-write]</dt>
		1121	<dd>
		1122	<p>The current reschedule callback, or <code>0</code>, if this functionality is
		1123	switched off. Can be changed any time, but changes only take effect when
		1124	the periodic timer fires or <code>ev_periodic_again</code> is being called.</p>
		1125	</dd>
599	</dl>	1126	</dl>
		1127	<p>Example: Call a callback every hour, or, more precisely, whenever the
		1128	system clock is divisible by 3600. The callback invocation times have
		1129	potentially a lot of jittering, but good long-term stability.</p>
		1130	<pre> static void
		1131	clock_cb (struct ev_loop loop, struct ev_io w, int revents)
		1132	{
		1133	... its now a full hour (UTC, or TAI or whatever your clock follows)
		1134	}
600		1135
		1136	struct ev_periodic hourly_tick;
		1137	ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);
		1138	ev_periodic_start (loop, &hourly_tick);
		1139
		1140	</pre>
		1141	<p>Example: The same as above, but use a reschedule callback to do it:</p>
		1142	<pre> #include <math.h>
		1143
		1144	static ev_tstamp
		1145	my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)
		1146	{
		1147	return fmod (now, 3600.) + 3600.;
		1148	}
		1149
		1150	ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);
		1151
		1152	</pre>
		1153	<p>Example: Call a callback every hour, starting now:</p>
		1154	<pre> struct ev_periodic hourly_tick;
		1155	ev_periodic_init (&hourly_tick, clock_cb,
		1156	fmod (ev_now (loop), 3600.), 3600., 0);
		1157	ev_periodic_start (loop, &hourly_tick);
		1158
		1159
		1160
		1161
		1162	</pre>
		1163
601	</div>	1164	</div>
602	<h2 id="code_ev_signal_code_signal_me_when_a"><code>ev_signal</code> - signal me when a signal gets signalled</h2>	1165	<h2 id="code_ev_signal_code_signal_me_when_a"><code>ev_signal</code> - signal me when a signal gets signalled!</h2>
603	<div id="code_ev_signal_code_signal_me_when_a-2">	1166	<div id="code_ev_signal_code_signal_me_when_a-2">
604	<p>Signal watchers will trigger an event when the process receives a specific	1167	<p>Signal watchers will trigger an event when the process receives a specific
605	signal one or more times. Even though signals are very asynchronous, libev	1168	signal one or more times. Even though signals are very asynchronous, libev
606	will try it's best to deliver signals synchronously, i.e. as part of the	1169	will try it's best to deliver signals synchronously, i.e. as part of the
607	normal event processing, like any other event.</p>	1170	normal event processing, like any other event.</p>
608	<p>You cna configure as many watchers as you like per signal. Only when the	1171	<p>You can configure as many watchers as you like per signal. Only when the
609	first watcher gets started will libev actually register a signal watcher	1172	first watcher gets started will libev actually register a signal watcher
610	with the kernel (thus it coexists with your own signal handlers as long	1173	with the kernel (thus it coexists with your own signal handlers as long
611	as you don't register any with libev). Similarly, when the last signal	1174	as you don't register any with libev). Similarly, when the last signal
612	watcher for a signal is stopped libev will reset the signal handler to	1175	watcher for a signal is stopped libev will reset the signal handler to
613	SIG_DFL (regardless of what it was set to before).</p>	1176	SIG_DFL (regardless of what it was set to before).</p>
…		…
616	<dt>ev_signal_set (ev_signal *, int signum)</dt>	1179	<dt>ev_signal_set (ev_signal *, int signum)</dt>
617	<dd>	1180	<dd>
618	<p>Configures the watcher to trigger on the given signal number (usually one	1181	<p>Configures the watcher to trigger on the given signal number (usually one
619	of the <code>SIGxxx</code> constants).</p>	1182	of the <code>SIGxxx</code> constants).</p>
620	</dd>	1183	</dd>
		1184	<dt>int signum [read-only]</dt>
		1185	<dd>
		1186	<p>The signal the watcher watches out for.</p>
		1187	</dd>
621	</dl>	1188	</dl>
622		1189
		1190
		1191
		1192
		1193
623	</div>	1194	</div>
624	<h2 id="code_ev_child_code_wait_for_pid_stat"><code>ev_child</code> - wait for pid status changes</h2>	1195	<h2 id="code_ev_child_code_watch_out_for_pro"><code>ev_child</code> - watch out for process status changes</h2>
625	<div id="code_ev_child_code_wait_for_pid_stat-2">	1196	<div id="code_ev_child_code_watch_out_for_pro-2">
626	<p>Child watchers trigger when your process receives a SIGCHLD in response to	1197	<p>Child watchers trigger when your process receives a SIGCHLD in response to
627	some child status changes (most typically when a child of yours dies).</p>	1198	some child status changes (most typically when a child of yours dies).</p>
628	<dl>	1199	<dl>
629	<dt>ev_child_init (ev_child *, callback, int pid)</dt>	1200	<dt>ev_child_init (ev_child *, callback, int pid)</dt>
630	<dt>ev_child_set (ev_child *, int pid)</dt>	1201	<dt>ev_child_set (ev_child *, int pid)</dt>
631	<dd>	1202	<dd>
632	<p>Configures the watcher to wait for status changes of process <code>pid</code> (or	1203	<p>Configures the watcher to wait for status changes of process <code>pid</code> (or
633	<i>any</i> process if <code>pid</code> is specified as <code>0</code>). The callback can look	1204	<i>any</i> process if <code>pid</code> is specified as <code>0</code>). The callback can look
634	at the <code>rstatus</code> member of the <code>ev_child</code> watcher structure to see	1205	at the <code>rstatus</code> member of the <code>ev_child</code> watcher structure to see
635	the status word (use the macros from <code>sys/wait.h</code>). The <code>rpid</code> member	1206	the status word (use the macros from <code>sys/wait.h</code> and see your systems
		1207	<code>waitpid</code> documentation). The <code>rpid</code> member contains the pid of the
636	contains the pid of the process causing the status change.</p>	1208	process causing the status change.</p>
		1209	</dd>
		1210	<dt>int pid [read-only]</dt>
		1211	<dd>
		1212	<p>The process id this watcher watches out for, or <code>0</code>, meaning any process id.</p>
		1213	</dd>
		1214	<dt>int rpid [read-write]</dt>
		1215	<dd>
		1216	<p>The process id that detected a status change.</p>
		1217	</dd>
		1218	<dt>int rstatus [read-write]</dt>
		1219	<dd>
		1220	<p>The process exit/trace status caused by <code>rpid</code> (see your systems
		1221	<code>waitpid</code> and <code>sys/wait.h</code> documentation for details).</p>
637	</dd>	1222	</dd>
638	</dl>	1223	</dl>
		1224	<p>Example: Try to exit cleanly on SIGINT and SIGTERM.</p>
		1225	<pre> static void
		1226	sigint_cb (struct ev_loop loop, struct ev_signal w, int revents)
		1227	{
		1228	ev_unloop (loop, EVUNLOOP_ALL);
		1229	}
639		1230
		1231	struct ev_signal signal_watcher;
		1232	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);
		1233	ev_signal_start (loop, &sigint_cb);
		1234
		1235
		1236
		1237
		1238	</pre>
		1239
640	</div>	1240	</div>
		1241	<h2 id="code_ev_stat_code_did_the_file_attri"><code>ev_stat</code> - did the file attributes just change?</h2>
		1242	<div id="code_ev_stat_code_did_the_file_attri-2">
		1243	<p>This watches a filesystem path for attribute changes. That is, it calls
		1244	<code>stat</code> regularly (or when the OS says it changed) and sees if it changed
		1245	compared to the last time, invoking the callback if it did.</p>
		1246	<p>The path does not need to exist: changing from "path exists" to "path does
		1247	not exist" is a status change like any other. The condition "path does
		1248	not exist" is signified by the <code>st_nlink</code> field being zero (which is
		1249	otherwise always forced to be at least one) and all the other fields of
		1250	the stat buffer having unspecified contents.</p>
		1251	<p>Since there is no standard to do this, the portable implementation simply
		1252	calls <code>stat (2)</code> regularly on the path to see if it changed somehow. You
		1253	can specify a recommended polling interval for this case. If you specify
		1254	a polling interval of <code>0</code> (highly recommended!) then a <i>suitable,
		1255	unspecified default</i> value will be used (which you can expect to be around
		1256	five seconds, although this might change dynamically). Libev will also
		1257	impose a minimum interval which is currently around <code>0.1</code>, but thats
		1258	usually overkill.</p>
		1259	<p>This watcher type is not meant for massive numbers of stat watchers,
		1260	as even with OS-supported change notifications, this can be
		1261	resource-intensive.</p>
		1262	<p>At the time of this writing, only the Linux inotify interface is
		1263	implemented (implementing kqueue support is left as an exercise for the
		1264	reader). Inotify will be used to give hints only and should not change the
		1265	semantics of <code>ev_stat</code> watchers, which means that libev sometimes needs
		1266	to fall back to regular polling again even with inotify, but changes are
		1267	usually detected immediately, and if the file exists there will be no
		1268	polling.</p>
		1269	<dl>
		1270	<dt>ev_stat_init (ev_stat , callback, const char path, ev_tstamp interval)</dt>
		1271	<dt>ev_stat_set (ev_stat , const char path, ev_tstamp interval)</dt>
		1272	<dd>
		1273	<p>Configures the watcher to wait for status changes of the given
		1274	<code>path</code>. The <code>interval</code> is a hint on how quickly a change is expected to
		1275	be detected and should normally be specified as <code>0</code> to let libev choose
		1276	a suitable value. The memory pointed to by <code>path</code> must point to the same
		1277	path for as long as the watcher is active.</p>
		1278	<p>The callback will be receive <code>EV_STAT</code> when a change was detected,
		1279	relative to the attributes at the time the watcher was started (or the
		1280	last change was detected).</p>
		1281	</dd>
		1282	<dt>ev_stat_stat (ev_stat *)</dt>
		1283	<dd>
		1284	<p>Updates the stat buffer immediately with new values. If you change the
		1285	watched path in your callback, you could call this fucntion to avoid
		1286	detecting this change (while introducing a race condition). Can also be
		1287	useful simply to find out the new values.</p>
		1288	</dd>
		1289	<dt>ev_statdata attr [read-only]</dt>
		1290	<dd>
		1291	<p>The most-recently detected attributes of the file. Although the type is of
		1292	<code>ev_statdata</code>, this is usually the (or one of the) <code>struct stat</code> types
		1293	suitable for your system. If the <code>st_nlink</code> member is <code>0</code>, then there
		1294	was some error while <code>stat</code>ing the file.</p>
		1295	</dd>
		1296	<dt>ev_statdata prev [read-only]</dt>
		1297	<dd>
		1298	<p>The previous attributes of the file. The callback gets invoked whenever
		1299	<code>prev</code> != <code>attr</code>.</p>
		1300	</dd>
		1301	<dt>ev_tstamp interval [read-only]</dt>
		1302	<dd>
		1303	<p>The specified interval.</p>
		1304	</dd>
		1305	<dt>const char *path [read-only]</dt>
		1306	<dd>
		1307	<p>The filesystem path that is being watched.</p>
		1308	</dd>
		1309	</dl>
		1310	<p>Example: Watch <code>/etc/passwd</code> for attribute changes.</p>
		1311	<pre> static void
		1312	passwd_cb (struct ev_loop loop, ev_stat w, int revents)
		1313	{
		1314	/* /etc/passwd changed in some way */
		1315	if (w->attr.st_nlink)
		1316	{
		1317	printf ("passwd current size %ld\n", (long)w->attr.st_size);
		1318	printf ("passwd current atime %ld\n", (long)w->attr.st_mtime);
		1319	printf ("passwd current mtime %ld\n", (long)w->attr.st_mtime);
		1320	}
		1321	else
		1322	/* you shalt not abuse printf for puts */
		1323	puts ("wow, /etc/passwd is not there, expect problems. "
		1324	"if this is windows, they already arrived\n");
		1325	}
		1326
		1327	...
		1328	ev_stat passwd;
		1329
		1330	ev_stat_init (&passwd, passwd_cb, "/etc/passwd");
		1331	ev_stat_start (loop, &passwd);
		1332
		1333
		1334
		1335
		1336	</pre>
		1337
		1338	</div>
641	<h2 id="code_ev_idle_code_when_you_ve_got_no"><code>ev_idle</code> - when you've got nothing better to do</h2>	1339	<h2 id="code_ev_idle_code_when_you_ve_got_no"><code>ev_idle</code> - when you've got nothing better to do...</h2>
642	<div id="code_ev_idle_code_when_you_ve_got_no-2">	1340	<div id="code_ev_idle_code_when_you_ve_got_no-2">
643	<p>Idle watchers trigger events when there are no other I/O or timer (or	1341	<p>Idle watchers trigger events when there are no other events are pending
644	periodic) events pending. That is, as long as your process is busy	1342	(prepare, check and other idle watchers do not count). That is, as long
645	handling sockets or timeouts it will not be called. But when your process	1343	as your process is busy handling sockets or timeouts (or even signals,
646	is idle all idle watchers are being called again and again - until	1344	imagine) it will not be triggered. But when your process is idle all idle
		1345	watchers are being called again and again, once per event loop iteration -
647	stopped, that is, or your process receives more events.</p>	1346	until stopped, that is, or your process receives more events and becomes
		1347	busy.</p>
648	<p>The most noteworthy effect is that as long as any idle watchers are	1348	<p>The most noteworthy effect is that as long as any idle watchers are
649	active, the process will not block when waiting for new events.</p>	1349	active, the process will not block when waiting for new events.</p>
650	<p>Apart from keeping your process non-blocking (which is a useful	1350	<p>Apart from keeping your process non-blocking (which is a useful
651	effect on its own sometimes), idle watchers are a good place to do	1351	effect on its own sometimes), idle watchers are a good place to do
652	"pseudo-background processing", or delay processing stuff to after the	1352	"pseudo-background processing", or delay processing stuff to after the
…		…
657	<p>Initialises and configures the idle watcher - it has no parameters of any	1357	<p>Initialises and configures the idle watcher - it has no parameters of any
658	kind. There is a <code>ev_idle_set</code> macro, but using it is utterly pointless,	1358	kind. There is a <code>ev_idle_set</code> macro, but using it is utterly pointless,
659	believe me.</p>	1359	believe me.</p>
660	</dd>	1360	</dd>
661	</dl>	1361	</dl>
		1362	<p>Example: Dynamically allocate an <code>ev_idle</code> watcher, start it, and in the
		1363	callback, free it. Also, use no error checking, as usual.</p>
		1364	<pre> static void
		1365	idle_cb (struct ev_loop loop, struct ev_idle w, int revents)
		1366	{
		1367	free (w);
		1368	// now do something you wanted to do when the program has
		1369	// no longer asnything immediate to do.
		1370	}
662		1371
		1372	struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle));
		1373	ev_idle_init (idle_watcher, idle_cb);
		1374	ev_idle_start (loop, idle_cb);
		1375
		1376
		1377
		1378
		1379	</pre>
		1380
663	</div>	1381	</div>
664	<h2 id="prepare_and_check_your_hooks_into_th">prepare and check - your hooks into the event loop</h2>	1382	<h2 id="code_ev_prepare_code_and_code_ev_che"><code>ev_prepare</code> and <code>ev_check</code> - customise your event loop!</h2>
665	<div id="prepare_and_check_your_hooks_into_th-2">	1383	<div id="code_ev_prepare_code_and_code_ev_che-2">
666	<p>Prepare and check watchers usually (but not always) are used in	1384	<p>Prepare and check watchers are usually (but not always) used in tandem:
667	tandom. Prepare watchers get invoked before the process blocks and check	1385	prepare watchers get invoked before the process blocks and check watchers
668	watchers afterwards.</p>	1386	afterwards.</p>
		1387	<p>You <i>must not</i> call <code>ev_loop</code> or similar functions that enter
		1388	the current event loop from either <code>ev_prepare</code> or <code>ev_check</code>
		1389	watchers. Other loops than the current one are fine, however. The
		1390	rationale behind this is that you do not need to check for recursion in
		1391	those watchers, i.e. the sequence will always be <code>ev_prepare</code>, blocking,
		1392	<code>ev_check</code> so if you have one watcher of each kind they will always be
		1393	called in pairs bracketing the blocking call.</p>
669	<p>Their main purpose is to integrate other event mechanisms into libev. This	1394	<p>Their main purpose is to integrate other event mechanisms into libev and
670	could be used, for example, to track variable changes, implement your own	1395	their use is somewhat advanced. This could be used, for example, to track
671	watchers, integrate net-snmp or a coroutine library and lots more.</p>	1396	variable changes, implement your own watchers, integrate net-snmp or a
		1397	coroutine library and lots more. They are also occasionally useful if
		1398	you cache some data and want to flush it before blocking (for example,
		1399	in X programs you might want to do an <code>XFlush ()</code> in an <code>ev_prepare</code>
		1400	watcher).</p>
672	<p>This is done by examining in each prepare call which file descriptors need	1401	<p>This is done by examining in each prepare call which file descriptors need
673	to be watched by the other library, registering <code>ev_io</code> watchers for them	1402	to be watched by the other library, registering <code>ev_io</code> watchers for
674	and starting an <code>ev_timer</code> watcher for any timeouts (many libraries provide	1403	them and starting an <code>ev_timer</code> watcher for any timeouts (many libraries
675	just this functionality). Then, in the check watcher you check for any	1404	provide just this functionality). Then, in the check watcher you check for
676	events that occured (by making your callbacks set soem flags for example)	1405	any events that occured (by checking the pending status of all watchers
677	and call back into the library.</p>	1406	and stopping them) and call back into the library. The I/O and timer
		1407	callbacks will never actually be called (but must be valid nevertheless,
		1408	because you never know, you know?).</p>
678	<p>As another example, the perl Coro module uses these hooks to integrate	1409	<p>As another example, the Perl Coro module uses these hooks to integrate
679	coroutines into libev programs, by yielding to other active coroutines	1410	coroutines into libev programs, by yielding to other active coroutines
680	during each prepare and only letting the process block if no coroutines	1411	during each prepare and only letting the process block if no coroutines
681	are ready to run.</p>	1412	are ready to run (it's actually more complicated: it only runs coroutines
		1413	with priority higher than or equal to the event loop and one coroutine
		1414	of lower priority, but only once, using idle watchers to keep the event
		1415	loop from blocking if lower-priority coroutines are active, thus mapping
		1416	low-priority coroutines to idle/background tasks).</p>
682	<dl>	1417	<dl>
683	<dt>ev_prepare_init (ev_prepare *, callback)</dt>	1418	<dt>ev_prepare_init (ev_prepare *, callback)</dt>
684	<dt>ev_check_init (ev_check *, callback)</dt>	1419	<dt>ev_check_init (ev_check *, callback)</dt>
685	<dd>	1420	<dd>
686	<p>Initialises and configures the prepare or check watcher - they have no	1421	<p>Initialises and configures the prepare or check watcher - they have no
687	parameters of any kind. There are <code>ev_prepare_set</code> and <code>ev_check_set</code>	1422	parameters of any kind. There are <code>ev_prepare_set</code> and <code>ev_check_set</code>
688	macros, but using them is utterly, utterly pointless.</p>	1423	macros, but using them is utterly, utterly and completely pointless.</p>
689	</dd>	1424	</dd>
690	</dl>	1425	</dl>
		1426	<p>Example: To include a library such as adns, you would add IO watchers
		1427	and a timeout watcher in a prepare handler, as required by libadns, and
		1428	in a check watcher, destroy them and call into libadns. What follows is
		1429	pseudo-code only of course:</p>
		1430	<pre> static ev_io iow [nfd];
		1431	static ev_timer tw;
691		1432
		1433	static void
		1434	io_cb (ev_loop loop, ev_io w, int revents)
		1435	{
		1436	// set the relevant poll flags
		1437	// could also call adns_processreadable etc. here
		1438	struct pollfd fd = (struct pollfd )w->data;
		1439	if (revents & EV_READ ) fd->revents \|= fd->events & POLLIN;
		1440	if (revents & EV_WRITE) fd->revents \|= fd->events & POLLOUT;
		1441	}
		1442
		1443	// create io watchers for each fd and a timer before blocking
		1444	static void
		1445	adns_prepare_cb (ev_loop loop, ev_prepare w, int revents)
		1446	{
		1447	int timeout = 3600000;truct pollfd fds [nfd];
		1448	// actual code will need to loop here and realloc etc.
		1449	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));
		1450
		1451	/* the callback is illegal, but won't be called as we stop during check */
		1452	ev_timer_init (&tw, 0, timeout * 1e-3);
		1453	ev_timer_start (loop, &tw);
		1454
		1455	// create on ev_io per pollfd
		1456	for (int i = 0; i < nfd; ++i)
		1457	{
		1458	ev_io_init (iow + i, io_cb, fds [i].fd,
		1459	((fds [i].events & POLLIN ? EV_READ : 0)
		1460	\| (fds [i].events & POLLOUT ? EV_WRITE : 0)));
		1461
		1462	fds [i].revents = 0;
		1463	iow [i].data = fds + i;
		1464	ev_io_start (loop, iow + i);
		1465	}
		1466	}
		1467
		1468	// stop all watchers after blocking
		1469	static void
		1470	adns_check_cb (ev_loop loop, ev_check w, int revents)
		1471	{
		1472	ev_timer_stop (loop, &tw);
		1473
		1474	for (int i = 0; i < nfd; ++i)
		1475	ev_io_stop (loop, iow + i);
		1476
		1477	adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));
		1478	}
		1479
		1480
		1481
		1482
		1483	</pre>
		1484
692	</div>	1485	</div>
693	<h1 id="OTHER_FUNCTIONS">OTHER FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p>	1486	<h2 id="code_ev_embed_code_when_one_backend_"><code>ev_embed</code> - when one backend isn't enough...</h2>
		1487	<div id="code_ev_embed_code_when_one_backend_-2">
		1488	<p>This is a rather advanced watcher type that lets you embed one event loop
		1489	into another (currently only <code>ev_io</code> events are supported in the embedded
		1490	loop, other types of watchers might be handled in a delayed or incorrect
		1491	fashion and must not be used).</p>
		1492	<p>There are primarily two reasons you would want that: work around bugs and
		1493	prioritise I/O.</p>
		1494	<p>As an example for a bug workaround, the kqueue backend might only support
		1495	sockets on some platform, so it is unusable as generic backend, but you
		1496	still want to make use of it because you have many sockets and it scales
		1497	so nicely. In this case, you would create a kqueue-based loop and embed it
		1498	into your default loop (which might use e.g. poll). Overall operation will
		1499	be a bit slower because first libev has to poll and then call kevent, but
		1500	at least you can use both at what they are best.</p>
		1501	<p>As for prioritising I/O: rarely you have the case where some fds have
		1502	to be watched and handled very quickly (with low latency), and even
		1503	priorities and idle watchers might have too much overhead. In this case
		1504	you would put all the high priority stuff in one loop and all the rest in
		1505	a second one, and embed the second one in the first.</p>
		1506	<p>As long as the watcher is active, the callback will be invoked every time
		1507	there might be events pending in the embedded loop. The callback must then
		1508	call <code>ev_embed_sweep (mainloop, watcher)</code> to make a single sweep and invoke
		1509	their callbacks (you could also start an idle watcher to give the embedded
		1510	loop strictly lower priority for example). You can also set the callback
		1511	to <code>0</code>, in which case the embed watcher will automatically execute the
		1512	embedded loop sweep.</p>
		1513	<p>As long as the watcher is started it will automatically handle events. The
		1514	callback will be invoked whenever some events have been handled. You can
		1515	set the callback to <code>0</code> to avoid having to specify one if you are not
		1516	interested in that.</p>
		1517	<p>Also, there have not currently been made special provisions for forking:
		1518	when you fork, you not only have to call <code>ev_loop_fork</code> on both loops,
		1519	but you will also have to stop and restart any <code>ev_embed</code> watchers
		1520	yourself.</p>
		1521	<p>Unfortunately, not all backends are embeddable, only the ones returned by
		1522	<code>ev_embeddable_backends</code> are, which, unfortunately, does not include any
		1523	portable one.</p>
		1524	<p>So when you want to use this feature you will always have to be prepared
		1525	that you cannot get an embeddable loop. The recommended way to get around
		1526	this is to have a separate variables for your embeddable loop, try to
		1527	create it, and if that fails, use the normal loop for everything:</p>
		1528	<pre> struct ev_loop *loop_hi = ev_default_init (0);
		1529	struct ev_loop *loop_lo = 0;
		1530	struct ev_embed embed;
		1531
		1532	// see if there is a chance of getting one that works
		1533	// (remember that a flags value of 0 means autodetection)
		1534	loop_lo = ev_embeddable_backends () & ev_recommended_backends ()
		1535	? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ())
		1536	: 0;
		1537
		1538	// if we got one, then embed it, otherwise default to loop_hi
		1539	if (loop_lo)
		1540	{
		1541	ev_embed_init (&embed, 0, loop_lo);
		1542	ev_embed_start (loop_hi, &embed);
		1543	}
		1544	else
		1545	loop_lo = loop_hi;
		1546
		1547	</pre>
		1548	<dl>
		1549	<dt>ev_embed_init (ev_embed , callback, struct ev_loop embedded_loop)</dt>
		1550	<dt>ev_embed_set (ev_embed , callback, struct ev_loop embedded_loop)</dt>
		1551	<dd>
		1552	<p>Configures the watcher to embed the given loop, which must be
		1553	embeddable. If the callback is <code>0</code>, then <code>ev_embed_sweep</code> will be
		1554	invoked automatically, otherwise it is the responsibility of the callback
		1555	to invoke it (it will continue to be called until the sweep has been done,
		1556	if you do not want thta, you need to temporarily stop the embed watcher).</p>
		1557	</dd>
		1558	<dt>ev_embed_sweep (loop, ev_embed *)</dt>
		1559	<dd>
		1560	<p>Make a single, non-blocking sweep over the embedded loop. This works
		1561	similarly to <code>ev_loop (embedded_loop, EVLOOP_NONBLOCK)</code>, but in the most
		1562	apropriate way for embedded loops.</p>
		1563	</dd>
		1564	<dt>struct ev_loop *loop [read-only]</dt>
		1565	<dd>
		1566	<p>The embedded event loop.</p>
		1567	</dd>
		1568	</dl>
		1569
		1570
		1571
		1572
		1573
		1574	</div>
		1575	<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>
		1576	<div id="code_ev_fork_code_the_audacity_to_re-2">
		1577	<p>Fork watchers are called when a <code>fork ()</code> was detected (usually because
		1578	whoever is a good citizen cared to tell libev about it by calling
		1579	<code>ev_default_fork</code> or <code>ev_loop_fork</code>). The invocation is done before the
		1580	event loop blocks next and before <code>ev_check</code> watchers are being called,
		1581	and only in the child after the fork. If whoever good citizen calling
		1582	<code>ev_default_fork</code> cheats and calls it in the wrong process, the fork
		1583	handlers will be invoked, too, of course.</p>
		1584	<dl>
		1585	<dt>ev_fork_init (ev_signal *, callback)</dt>
		1586	<dd>
		1587	<p>Initialises and configures the fork watcher - it has no parameters of any
		1588	kind. There is a <code>ev_fork_set</code> macro, but using it is utterly pointless,
		1589	believe me.</p>
		1590	</dd>
		1591	</dl>
		1592
		1593
		1594
		1595
		1596
		1597	</div>
		1598	<h1 id="OTHER_FUNCTIONS">OTHER FUNCTIONS</h1>
694	<div id="OTHER_FUNCTIONS_CONTENT">	1599	<div id="OTHER_FUNCTIONS_CONTENT">
695	<p>There are some other fucntions of possible interest. Described. Here. Now.</p>	1600	<p>There are some other functions of possible interest. Described. Here. Now.</p>
696	<dl>	1601	<dl>
697	<dt>ev_once (loop, int fd, int events, ev_tstamp timeout, callback)</dt>	1602	<dt>ev_once (loop, int fd, int events, ev_tstamp timeout, callback)</dt>
698	<dd>	1603	<dd>
699	<p>This function combines a simple timer and an I/O watcher, calls your	1604	<p>This function combines a simple timer and an I/O watcher, calls your
700	callback on whichever event happens first and automatically stop both	1605	callback on whichever event happens first and automatically stop both
701	watchers. This is useful if you want to wait for a single event on an fd	1606	watchers. This is useful if you want to wait for a single event on an fd
702	or timeout without havign to allocate/configure/start/stop/free one or	1607	or timeout without having to allocate/configure/start/stop/free one or
703	more watchers yourself.</p>	1608	more watchers yourself.</p>
704	<p>If <code>fd</code> is less than 0, then no I/O watcher will be started and events is	1609	<p>If <code>fd</code> is less than 0, then no I/O watcher will be started and events
705	ignored. Otherwise, an <code>ev_io</code> watcher for the given <code>fd</code> and <code>events</code> set	1610	is being ignored. Otherwise, an <code>ev_io</code> watcher for the given <code>fd</code> and
706	will be craeted and started.</p>	1611	<code>events</code> set will be craeted and started.</p>
707	<p>If <code>timeout</code> is less than 0, then no timeout watcher will be	1612	<p>If <code>timeout</code> is less than 0, then no timeout watcher will be
708	started. Otherwise an <code>ev_timer</code> watcher with after = <code>timeout</code> (and repeat	1613	started. Otherwise an <code>ev_timer</code> watcher with after = <code>timeout</code> (and
709	= 0) will be started.</p>	1614	repeat = 0) will be started. While <code>0</code> is a valid timeout, it is of
		1615	dubious value.</p>
710	<p>The callback has the type <code>void (cb)(int revents, void arg)</code> and	1616	<p>The callback has the type <code>void (cb)(int revents, void arg)</code> and gets
711	gets passed an events set (normally a combination of <code>EV_ERROR</code>, <code>EV_READ</code>,	1617	passed an <code>revents</code> set like normal event callbacks (a combination of
712	<code>EV_WRITE</code> or <code>EV_TIMEOUT</code>) and the <code>arg</code> value passed to <code>ev_once</code>:</p>	1618	<code>EV_ERROR</code>, <code>EV_READ</code>, <code>EV_WRITE</code> or <code>EV_TIMEOUT</code>) and the <code>arg</code>
		1619	value passed to <code>ev_once</code>:</p>
713	<pre> static void stdin_ready (int revents, void *arg)	1620	<pre> static void stdin_ready (int revents, void *arg)
714	{	1621	{
715	if (revents & EV_TIMEOUT)	1622	if (revents & EV_TIMEOUT)
716	/* doh, nothing entered */	1623	/* doh, nothing entered */;
717	else if (revents & EV_READ)	1624	else if (revents & EV_READ)
718	/* stdin might have data for us, joy! */	1625	/* stdin might have data for us, joy! */;
719	}	1626	}
720		1627
721	ev_once (STDIN_FILENO, EV_READm 10., stdin_ready, 0);	1628	ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);
722		1629
723	</pre>	1630	</pre>
724	</dd>	1631	</dd>
725	<dt>ev_feed_event (loop, watcher, int events)</dt>	1632	<dt>ev_feed_event (ev_loop , watcher , int revents)</dt>
726	<dd>	1633	<dd>
727	<p>Feeds the given event set into the event loop, as if the specified event	1634	<p>Feeds the given event set into the event loop, as if the specified event
728	has happened for the specified watcher (which must be a pointer to an	1635	had happened for the specified watcher (which must be a pointer to an
729	initialised but not necessarily active event watcher).</p>	1636	initialised but not necessarily started event watcher).</p>
730	</dd>	1637	</dd>
731	<dt>ev_feed_fd_event (loop, int fd, int revents)</dt>	1638	<dt>ev_feed_fd_event (ev_loop *, int fd, int revents)</dt>
732	<dd>	1639	<dd>
733	<p>Feed an event on the given fd, as if a file descriptor backend detected it.</p>	1640	<p>Feed an event on the given fd, as if a file descriptor backend detected
		1641	the given events it.</p>
734	</dd>	1642	</dd>
735	<dt>ev_feed_signal_event (loop, int signum)</dt>	1643	<dt>ev_feed_signal_event (ev_loop *loop, int signum)</dt>
736	<dd>	1644	<dd>
737	<p>Feed an event as if the given signal occured (loop must be the default loop!).</p>	1645	<p>Feed an event as if the given signal occured (<code>loop</code> must be the default
		1646	loop!).</p>
738	</dd>	1647	</dd>
739	</dl>	1648	</dl>
740		1649
		1650
		1651
		1652
		1653
741	</div>	1654	</div>
742	<h1 id="AUTHOR">AUTHOR</h1><p><a href="#TOP" class="toplink">Top</a></p>	1655	<h1 id="LIBEVENT_EMULATION">LIBEVENT EMULATION</h1>
		1656	<div id="LIBEVENT_EMULATION_CONTENT">
		1657	<p>Libev offers a compatibility emulation layer for libevent. It cannot
		1658	emulate the internals of libevent, so here are some usage hints:</p>
		1659	<dl>
		1660	<dt>* Use it by including <event.h>, as usual.</dt>
		1661	<dt>* The following members are fully supported: ev_base, ev_callback,
		1662	ev_arg, ev_fd, ev_res, ev_events.</dt>
		1663	<dt>* Avoid using ev_flags and the EVLIST_*-macros, while it is
		1664	maintained by libev, it does not work exactly the same way as in libevent (consider
		1665	it a private API).</dt>
		1666	<dt>* Priorities are not currently supported. Initialising priorities
		1667	will fail and all watchers will have the same priority, even though there
		1668	is an ev_pri field.</dt>
		1669	<dt>* Other members are not supported.</dt>
		1670	<dt>* The libev emulation is <i>not</i> ABI compatible to libevent, you need
		1671	to use the libev header file and library.</dt>
		1672	</dl>
		1673
		1674	</div>
		1675	<h1 id="C_SUPPORT">C++ SUPPORT</h1>
		1676	<div id="C_SUPPORT_CONTENT">
		1677	<p>Libev comes with some simplistic wrapper classes for C++ that mainly allow
		1678	you to use some convinience methods to start/stop watchers and also change
		1679	the callback model to a model using method callbacks on objects.</p>
		1680	<p>To use it,</p>
		1681	<pre> #include <ev++.h>
		1682
		1683	</pre>
		1684	<p>(it is not installed by default). This automatically includes <cite>ev.h</cite>
		1685	and puts all of its definitions (many of them macros) into the global
		1686	namespace. All C++ specific things are put into the <code>ev</code> namespace.</p>
		1687	<p>It should support all the same embedding options as <cite>ev.h</cite>, most notably
		1688	<code>EV_MULTIPLICITY</code>.</p>
		1689	<p>Here is a list of things available in the <code>ev</code> namespace:</p>
		1690	<dl>
		1691	<dt><code>ev::READ</code>, <code>ev::WRITE</code> etc.</dt>
		1692	<dd>
		1693	<p>These are just enum values with the same values as the <code>EV_READ</code> etc.
		1694	macros from <cite>ev.h</cite>.</p>
		1695	</dd>
		1696	<dt><code>ev::tstamp</code>, <code>ev::now</code></dt>
		1697	<dd>
		1698	<p>Aliases to the same types/functions as with the <code>ev_</code> prefix.</p>
		1699	</dd>
		1700	<dt><code>ev::io</code>, <code>ev::timer</code>, <code>ev::periodic</code>, <code>ev::idle</code>, <code>ev::sig</code> etc.</dt>
		1701	<dd>
		1702	<p>For each <code>ev_TYPE</code> watcher in <cite>ev.h</cite> there is a corresponding class of
		1703	the same name in the <code>ev</code> namespace, with the exception of <code>ev_signal</code>
		1704	which is called <code>ev::sig</code> to avoid clashes with the <code>signal</code> macro
		1705	defines by many implementations.</p>
		1706	<p>All of those classes have these methods:</p>
		1707	<p>
		1708	<dl>
		1709	<dt>ev::TYPE::TYPE (object , object::method )</dt>
		1710	<dt>ev::TYPE::TYPE (object , object::method , struct ev_loop *)</dt>
		1711	<dt>ev::TYPE::~TYPE</dt>
		1712	<dd>
		1713	<p>The constructor takes a pointer to an object and a method pointer to
		1714	the event handler callback to call in this class. The constructor calls
		1715	<code>ev_init</code> for you, which means you have to call the <code>set</code> method
		1716	before starting it. If you do not specify a loop then the constructor
		1717	automatically associates the default loop with this watcher.</p>
		1718	<p>The destructor automatically stops the watcher if it is active.</p>
		1719	</dd>
		1720	<dt>w->set (struct ev_loop *)</dt>
		1721	<dd>
		1722	<p>Associates a different <code>struct ev_loop</code> with this watcher. You can only
		1723	do this when the watcher is inactive (and not pending either).</p>
		1724	</dd>
		1725	<dt>w->set ([args])</dt>
		1726	<dd>
		1727	<p>Basically the same as <code>ev_TYPE_set</code>, with the same args. Must be
		1728	called at least once. Unlike the C counterpart, an active watcher gets
		1729	automatically stopped and restarted.</p>
		1730	</dd>
		1731	<dt>w->start ()</dt>
		1732	<dd>
		1733	<p>Starts the watcher. Note that there is no <code>loop</code> argument as the
		1734	constructor already takes the loop.</p>
		1735	</dd>
		1736	<dt>w->stop ()</dt>
		1737	<dd>
		1738	<p>Stops the watcher if it is active. Again, no <code>loop</code> argument.</p>
		1739	</dd>
		1740	<dt>w->again () <code>ev::timer</code>, <code>ev::periodic</code> only</dt>
		1741	<dd>
		1742	<p>For <code>ev::timer</code> and <code>ev::periodic</code>, this invokes the corresponding
		1743	<code>ev_TYPE_again</code> function.</p>
		1744	</dd>
		1745	<dt>w->sweep () <code>ev::embed</code> only</dt>
		1746	<dd>
		1747	<p>Invokes <code>ev_embed_sweep</code>.</p>
		1748	</dd>
		1749	<dt>w->update () <code>ev::stat</code> only</dt>
		1750	<dd>
		1751	<p>Invokes <code>ev_stat_stat</code>.</p>
		1752	</dd>
		1753	</dl>
		1754	</p>
		1755	</dd>
		1756	</dl>
		1757	<p>Example: Define a class with an IO and idle watcher, start one of them in
		1758	the constructor.</p>
		1759	<pre> class myclass
		1760	{
		1761	ev_io io; void io_cb (ev::io &w, int revents);
		1762	ev_idle idle void idle_cb (ev::idle &w, int revents);
		1763
		1764	myclass ();
		1765	}
		1766
		1767	myclass::myclass (int fd)
		1768	: io (this, &myclass::io_cb),
		1769	idle (this, &myclass::idle_cb)
		1770	{
		1771	io.start (fd, ev::READ);
		1772	}
		1773
		1774
		1775
		1776
		1777	</pre>
		1778
		1779	</div>
		1780	<h1 id="MACRO_MAGIC">MACRO MAGIC</h1>
		1781	<div id="MACRO_MAGIC_CONTENT">
		1782	<p>Libev can be compiled with a variety of options, the most fundemantal is
		1783	<code>EV_MULTIPLICITY</code>. This option determines wether (most) functions and
		1784	callbacks have an initial <code>struct ev_loop *</code> argument.</p>
		1785	<p>To make it easier to write programs that cope with either variant, the
		1786	following macros are defined:</p>
		1787	<dl>
		1788	<dt><code>EV_A</code>, <code>EV_A_</code></dt>
		1789	<dd>
		1790	<p>This provides the loop <i>argument</i> for functions, if one is required ("ev
		1791	loop argument"). The <code>EV_A</code> form is used when this is the sole argument,
		1792	<code>EV_A_</code> is used when other arguments are following. Example:</p>
		1793	<pre> ev_unref (EV_A);
		1794	ev_timer_add (EV_A_ watcher);
		1795	ev_loop (EV_A_ 0);
		1796
		1797	</pre>
		1798	<p>It assumes the variable <code>loop</code> of type <code>struct ev_loop *</code> is in scope,
		1799	which is often provided by the following macro.</p>
		1800	</dd>
		1801	<dt><code>EV_P</code>, <code>EV_P_</code></dt>
		1802	<dd>
		1803	<p>This provides the loop <i>parameter</i> for functions, if one is required ("ev
		1804	loop parameter"). The <code>EV_P</code> form is used when this is the sole parameter,
		1805	<code>EV_P_</code> is used when other parameters are following. Example:</p>
		1806	<pre> // this is how ev_unref is being declared
		1807	static void ev_unref (EV_P);
		1808
		1809	// this is how you can declare your typical callback
		1810	static void cb (EV_P_ ev_timer *w, int revents)
		1811
		1812	</pre>
		1813	<p>It declares a parameter <code>loop</code> of type <code>struct ev_loop *</code>, quite
		1814	suitable for use with <code>EV_A</code>.</p>
		1815	</dd>
		1816	<dt><code>EV_DEFAULT</code>, <code>EV_DEFAULT_</code></dt>
		1817	<dd>
		1818	<p>Similar to the other two macros, this gives you the value of the default
		1819	loop, if multiple loops are supported ("ev loop default").</p>
		1820	</dd>
		1821	</dl>
		1822	<p>Example: Declare and initialise a check watcher, working regardless of
		1823	wether multiple loops are supported or not.</p>
		1824	<pre> static void
		1825	check_cb (EV_P_ ev_timer *w, int revents)
		1826	{
		1827	ev_check_stop (EV_A_ w);
		1828	}
		1829
		1830	ev_check check;
		1831	ev_check_init (&check, check_cb);
		1832	ev_check_start (EV_DEFAULT_ &check);
		1833	ev_loop (EV_DEFAULT_ 0);
		1834
		1835
		1836
		1837
		1838	</pre>
		1839
		1840	</div>
		1841	<h1 id="EMBEDDING">EMBEDDING</h1>
		1842	<div id="EMBEDDING_CONTENT">
		1843	<p>Libev can (and often is) directly embedded into host
		1844	applications. Examples of applications that embed it include the Deliantra
		1845	Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe)
		1846	and rxvt-unicode.</p>
		1847	<p>The goal is to enable you to just copy the neecssary files into your
		1848	source directory without having to change even a single line in them, so
		1849	you can easily upgrade by simply copying (or having a checked-out copy of
		1850	libev somewhere in your source tree).</p>
		1851
		1852	</div>
		1853	<h2 id="FILESETS">FILESETS</h2>
		1854	<div id="FILESETS_CONTENT">
		1855	<p>Depending on what features you need you need to include one or more sets of files
		1856	in your app.</p>
		1857
		1858	</div>
		1859	<h3 id="CORE_EVENT_LOOP">CORE EVENT LOOP</h3>
		1860	<div id="CORE_EVENT_LOOP_CONTENT">
		1861	<p>To include only the libev core (all the <code>ev_*</code> functions), with manual
		1862	configuration (no autoconf):</p>
		1863	<pre> #define EV_STANDALONE 1
		1864	#include "ev.c"
		1865
		1866	</pre>
		1867	<p>This will automatically include <cite>ev.h</cite>, too, and should be done in a
		1868	single C source file only to provide the function implementations. To use
		1869	it, do the same for <cite>ev.h</cite> in all files wishing to use this API (best
		1870	done by writing a wrapper around <cite>ev.h</cite> that you can include instead and
		1871	where you can put other configuration options):</p>
		1872	<pre> #define EV_STANDALONE 1
		1873	#include "ev.h"
		1874
		1875	</pre>
		1876	<p>Both header files and implementation files can be compiled with a C++
		1877	compiler (at least, thats a stated goal, and breakage will be treated
		1878	as a bug).</p>
		1879	<p>You need the following files in your source tree, or in a directory
		1880	in your include path (e.g. in libev/ when using -Ilibev):</p>
		1881	<pre> ev.h
		1882	ev.c
		1883	ev_vars.h
		1884	ev_wrap.h
		1885
		1886	ev_win32.c required on win32 platforms only
		1887
		1888	ev_select.c only when select backend is enabled (which is by default)
		1889	ev_poll.c only when poll backend is enabled (disabled by default)
		1890	ev_epoll.c only when the epoll backend is enabled (disabled by default)
		1891	ev_kqueue.c only when the kqueue backend is enabled (disabled by default)
		1892	ev_port.c only when the solaris port backend is enabled (disabled by default)
		1893
		1894	</pre>
		1895	<p><cite>ev.c</cite> includes the backend files directly when enabled, so you only need
		1896	to compile this single file.</p>
		1897
		1898	</div>
		1899	<h3 id="LIBEVENT_COMPATIBILITY_API">LIBEVENT COMPATIBILITY API</h3>
		1900	<div id="LIBEVENT_COMPATIBILITY_API_CONTENT">
		1901	<p>To include the libevent compatibility API, also include:</p>
		1902	<pre> #include "event.c"
		1903
		1904	</pre>
		1905	<p>in the file including <cite>ev.c</cite>, and:</p>
		1906	<pre> #include "event.h"
		1907
		1908	</pre>
		1909	<p>in the files that want to use the libevent API. This also includes <cite>ev.h</cite>.</p>
		1910	<p>You need the following additional files for this:</p>
		1911	<pre> event.h
		1912	event.c
		1913
		1914	</pre>
		1915
		1916	</div>
		1917	<h3 id="AUTOCONF_SUPPORT">AUTOCONF SUPPORT</h3>
		1918	<div id="AUTOCONF_SUPPORT_CONTENT">
		1919	<p>Instead of using <code>EV_STANDALONE=1</code> and providing your config in
		1920	whatever way you want, you can also <code>m4_include([libev.m4])</code> in your
		1921	<cite>configure.ac</cite> and leave <code>EV_STANDALONE</code> undefined. <cite>ev.c</cite> will then
		1922	include <cite>config.h</cite> and configure itself accordingly.</p>
		1923	<p>For this of course you need the m4 file:</p>
		1924	<pre> libev.m4
		1925
		1926	</pre>
		1927
		1928	</div>
		1929	<h2 id="PREPROCESSOR_SYMBOLS_MACROS">PREPROCESSOR SYMBOLS/MACROS</h2>
		1930	<div id="PREPROCESSOR_SYMBOLS_MACROS_CONTENT">
		1931	<p>Libev can be configured via a variety of preprocessor symbols you have to define
		1932	before including any of its files. The default is not to build for multiplicity
		1933	and only include the select backend.</p>
		1934	<dl>
		1935	<dt>EV_STANDALONE</dt>
		1936	<dd>
		1937	<p>Must always be <code>1</code> if you do not use autoconf configuration, which
		1938	keeps libev from including <cite>config.h</cite>, and it also defines dummy
		1939	implementations for some libevent functions (such as logging, which is not
		1940	supported). It will also not define any of the structs usually found in
		1941	<cite>event.h</cite> that are not directly supported by the libev core alone.</p>
		1942	</dd>
		1943	<dt>EV_USE_MONOTONIC</dt>
		1944	<dd>
		1945	<p>If defined to be <code>1</code>, libev will try to detect the availability of the
		1946	monotonic clock option at both compiletime and runtime. Otherwise no use
		1947	of the monotonic clock option will be attempted. If you enable this, you
		1948	usually have to link against librt or something similar. Enabling it when
		1949	the functionality isn't available is safe, though, althoguh you have
		1950	to make sure you link against any libraries where the <code>clock_gettime</code>
		1951	function is hiding in (often <cite>-lrt</cite>).</p>
		1952	</dd>
		1953	<dt>EV_USE_REALTIME</dt>
		1954	<dd>
		1955	<p>If defined to be <code>1</code>, libev will try to detect the availability of the
		1956	realtime clock option at compiletime (and assume its availability at
		1957	runtime if successful). Otherwise no use of the realtime clock option will
		1958	be attempted. This effectively replaces <code>gettimeofday</code> by <code>clock_get
		1959	(CLOCK_REALTIME, ...)</code> and will not normally affect correctness. See tzhe note about libraries
		1960	in the description of <code>EV_USE_MONOTONIC</code>, though.</p>
		1961	</dd>
		1962	<dt>EV_USE_SELECT</dt>
		1963	<dd>
		1964	<p>If undefined or defined to be <code>1</code>, libev will compile in support for the
		1965	<code>select</code>(2) backend. No attempt at autodetection will be done: if no
		1966	other method takes over, select will be it. Otherwise the select backend
		1967	will not be compiled in.</p>
		1968	</dd>
		1969	<dt>EV_SELECT_USE_FD_SET</dt>
		1970	<dd>
		1971	<p>If defined to <code>1</code>, then the select backend will use the system <code>fd_set</code>
		1972	structure. This is useful if libev doesn't compile due to a missing
		1973	<code>NFDBITS</code> or <code>fd_mask</code> definition or it misguesses the bitset layout on
		1974	exotic systems. This usually limits the range of file descriptors to some
		1975	low limit such as 1024 or might have other limitations (winsocket only
		1976	allows 64 sockets). The <code>FD_SETSIZE</code> macro, set before compilation, might
		1977	influence the size of the <code>fd_set</code> used.</p>
		1978	</dd>
		1979	<dt>EV_SELECT_IS_WINSOCKET</dt>
		1980	<dd>
		1981	<p>When defined to <code>1</code>, the select backend will assume that
		1982	select/socket/connect etc. don't understand file descriptors but
		1983	wants osf handles on win32 (this is the case when the select to
		1984	be used is the winsock select). This means that it will call
		1985	<code>_get_osfhandle</code> on the fd to convert it to an OS handle. Otherwise,
		1986	it is assumed that all these functions actually work on fds, even
		1987	on win32. Should not be defined on non-win32 platforms.</p>
		1988	</dd>
		1989	<dt>EV_USE_POLL</dt>
		1990	<dd>
		1991	<p>If defined to be <code>1</code>, libev will compile in support for the <code>poll</code>(2)
		1992	backend. Otherwise it will be enabled on non-win32 platforms. It
		1993	takes precedence over select.</p>
		1994	</dd>
		1995	<dt>EV_USE_EPOLL</dt>
		1996	<dd>
		1997	<p>If defined to be <code>1</code>, libev will compile in support for the Linux
		1998	<code>epoll</code>(7) backend. Its availability will be detected at runtime,
		1999	otherwise another method will be used as fallback. This is the
		2000	preferred backend for GNU/Linux systems.</p>
		2001	</dd>
		2002	<dt>EV_USE_KQUEUE</dt>
		2003	<dd>
		2004	<p>If defined to be <code>1</code>, libev will compile in support for the BSD style
		2005	<code>kqueue</code>(2) backend. Its actual availability will be detected at runtime,
		2006	otherwise another method will be used as fallback. This is the preferred
		2007	backend for BSD and BSD-like systems, although on most BSDs kqueue only
		2008	supports some types of fds correctly (the only platform we found that
		2009	supports ptys for example was NetBSD), so kqueue might be compiled in, but
		2010	not be used unless explicitly requested. The best way to use it is to find
		2011	out whether kqueue supports your type of fd properly and use an embedded
		2012	kqueue loop.</p>
		2013	</dd>
		2014	<dt>EV_USE_PORT</dt>
		2015	<dd>
		2016	<p>If defined to be <code>1</code>, libev will compile in support for the Solaris
		2017	10 port style backend. Its availability will be detected at runtime,
		2018	otherwise another method will be used as fallback. This is the preferred
		2019	backend for Solaris 10 systems.</p>
		2020	</dd>
		2021	<dt>EV_USE_DEVPOLL</dt>
		2022	<dd>
		2023	<p>reserved for future expansion, works like the USE symbols above.</p>
		2024	</dd>
		2025	<dt>EV_USE_INOTIFY</dt>
		2026	<dd>
		2027	<p>If defined to be <code>1</code>, libev will compile in support for the Linux inotify
		2028	interface to speed up <code>ev_stat</code> watchers. Its actual availability will
		2029	be detected at runtime.</p>
		2030	</dd>
		2031	<dt>EV_H</dt>
		2032	<dd>
		2033	<p>The name of the <cite>ev.h</cite> header file used to include it. The default if
		2034	undefined is <code><ev.h></code> in <cite>event.h</cite> and <code>"ev.h"</code> in <cite>ev.c</cite>. This
		2035	can be used to virtually rename the <cite>ev.h</cite> header file in case of conflicts.</p>
		2036	</dd>
		2037	<dt>EV_CONFIG_H</dt>
		2038	<dd>
		2039	<p>If <code>EV_STANDALONE</code> isn't <code>1</code>, this variable can be used to override
		2040	<cite>ev.c</cite>'s idea of where to find the <cite>config.h</cite> file, similarly to
		2041	<code>EV_H</code>, above.</p>
		2042	</dd>
		2043	<dt>EV_EVENT_H</dt>
		2044	<dd>
		2045	<p>Similarly to <code>EV_H</code>, this macro can be used to override <cite>event.c</cite>'s idea
		2046	of how the <cite>event.h</cite> header can be found.</p>
		2047	</dd>
		2048	<dt>EV_PROTOTYPES</dt>
		2049	<dd>
		2050	<p>If defined to be <code>0</code>, then <cite>ev.h</cite> will not define any function
		2051	prototypes, but still define all the structs and other symbols. This is
		2052	occasionally useful if you want to provide your own wrapper functions
		2053	around libev functions.</p>
		2054	</dd>
		2055	<dt>EV_MULTIPLICITY</dt>
		2056	<dd>
		2057	<p>If undefined or defined to <code>1</code>, then all event-loop-specific functions
		2058	will have the <code>struct ev_loop *</code> as first argument, and you can create
		2059	additional independent event loops. Otherwise there will be no support
		2060	for multiple event loops and there is no first event loop pointer
		2061	argument. Instead, all functions act on the single default loop.</p>
		2062	</dd>
		2063	<dt>EV_PERIODIC_ENABLE</dt>
		2064	<dd>
		2065	<p>If undefined or defined to be <code>1</code>, then periodic timers are supported. If
		2066	defined to be <code>0</code>, then they are not. Disabling them saves a few kB of
		2067	code.</p>
		2068	</dd>
		2069	<dt>EV_EMBED_ENABLE</dt>
		2070	<dd>
		2071	<p>If undefined or defined to be <code>1</code>, then embed watchers are supported. If
		2072	defined to be <code>0</code>, then they are not.</p>
		2073	</dd>
		2074	<dt>EV_STAT_ENABLE</dt>
		2075	<dd>
		2076	<p>If undefined or defined to be <code>1</code>, then stat watchers are supported. If
		2077	defined to be <code>0</code>, then they are not.</p>
		2078	</dd>
		2079	<dt>EV_FORK_ENABLE</dt>
		2080	<dd>
		2081	<p>If undefined or defined to be <code>1</code>, then fork watchers are supported. If
		2082	defined to be <code>0</code>, then they are not.</p>
		2083	</dd>
		2084	<dt>EV_MINIMAL</dt>
		2085	<dd>
		2086	<p>If you need to shave off some kilobytes of code at the expense of some
		2087	speed, define this symbol to <code>1</code>. Currently only used for gcc to override
		2088	some inlining decisions, saves roughly 30% codesize of amd64.</p>
		2089	</dd>
		2090	<dt>EV_PID_HASHSIZE</dt>
		2091	<dd>
		2092	<p><code>ev_child</code> watchers use a small hash table to distribute workload by
		2093	pid. The default size is <code>16</code> (or <code>1</code> with <code>EV_MINIMAL</code>), usually more
		2094	than enough. If you need to manage thousands of children you might want to
		2095	increase this value (<i>must</i> be a power of two).</p>
		2096	</dd>
		2097	<dt>EV_INOTIFY_HASHSIZE</dt>
		2098	<dd>
		2099	<p><code>ev_staz</code> watchers use a small hash table to distribute workload by
		2100	inotify watch id. The default size is <code>16</code> (or <code>1</code> with <code>EV_MINIMAL</code>),
		2101	usually more than enough. If you need to manage thousands of <code>ev_stat</code>
		2102	watchers you might want to increase this value (<i>must</i> be a power of
		2103	two).</p>
		2104	</dd>
		2105	<dt>EV_COMMON</dt>
		2106	<dd>
		2107	<p>By default, all watchers have a <code>void *data</code> member. By redefining
		2108	this macro to a something else you can include more and other types of
		2109	members. You have to define it each time you include one of the files,
		2110	though, and it must be identical each time.</p>
		2111	<p>For example, the perl EV module uses something like this:</p>
		2112	<pre> #define EV_COMMON \
		2113	SV self; / contains this struct */ \
		2114	SV cb_sv, fh /* note no trailing ";" */
		2115
		2116	</pre>
		2117	</dd>
		2118	<dt>EV_CB_DECLARE (type)</dt>
		2119	<dt>EV_CB_INVOKE (watcher, revents)</dt>
		2120	<dt>ev_set_cb (ev, cb)</dt>
		2121	<dd>
		2122	<p>Can be used to change the callback member declaration in each watcher,
		2123	and the way callbacks are invoked and set. Must expand to a struct member
		2124	definition and a statement, respectively. See the <cite>ev.v</cite> header file for
		2125	their default definitions. One possible use for overriding these is to
		2126	avoid the <code>struct ev_loop *</code> as first argument in all cases, or to use
		2127	method calls instead of plain function calls in C++.</p>
		2128
		2129	</div>
		2130	<h2 id="EXAMPLES">EXAMPLES</h2>
		2131	<div id="EXAMPLES_CONTENT">
		2132	<p>For a real-world example of a program the includes libev
		2133	verbatim, you can have a look at the EV perl module
		2134	(<a href="http://software.schmorp.de/pkg/EV.html">http://software.schmorp.de/pkg/EV.html</a>). It has the libev files in
		2135	the <cite>libev/</cite> subdirectory and includes them in the <cite>EV/EVAPI.h</cite> (public
		2136	interface) and <cite>EV.xs</cite> (implementation) files. Only the <cite>EV.xs</cite> file
		2137	will be compiled. It is pretty complex because it provides its own header
		2138	file.</p>
		2139	<p>The usage in rxvt-unicode is simpler. It has a <cite>ev_cpp.h</cite> header file
		2140	that everybody includes and which overrides some autoconf choices:</p>
		2141	<pre> #define EV_USE_POLL 0
		2142	#define EV_MULTIPLICITY 0
		2143	#define EV_PERIODICS 0
		2144	#define EV_CONFIG_H <config.h>
		2145
		2146	#include "ev++.h"
		2147
		2148	</pre>
		2149	<p>And a <cite>ev_cpp.C</cite> implementation file that contains libev proper and is compiled:</p>
		2150	<pre> #include "ev_cpp.h"
		2151	#include "ev.c"
		2152
		2153
		2154
		2155
		2156	</pre>
		2157
		2158	</div>
		2159	<h1 id="COMPLEXITIES">COMPLEXITIES</h1>
		2160	<div id="COMPLEXITIES_CONTENT">
		2161	<p>In this section the complexities of (many of) the algorithms used inside
		2162	libev will be explained. For complexity discussions about backends see the
		2163	documentation for <code>ev_default_init</code>.</p>
		2164	<p>
		2165	<dl>
		2166	<dt>Starting and stopping timer/periodic watchers: O(log skipped_other_timers)</dt>
		2167	<dt>Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)</dt>
		2168	<dt>Starting io/check/prepare/idle/signal/child watchers: O(1)</dt>
		2169	<dt>Stopping check/prepare/idle watchers: O(1)</dt>
		2170	<dt>Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))</dt>
		2171	<dt>Finding the next timer per loop iteration: O(1)</dt>
		2172	<dt>Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)</dt>
		2173	<dt>Activating one watcher: O(1)</dt>
		2174	</dl>
		2175	</p>
		2176
		2177
		2178
		2179
		2180
		2181	</div>
		2182	<h1 id="AUTHOR">AUTHOR</h1>
743	<div id="AUTHOR_CONTENT">	2183	<div id="AUTHOR_CONTENT">
744	<p>Marc Lehmann <libev@schmorp.de>.</p>	2184	<p>Marc Lehmann <libev@schmorp.de>.</p>
745		2185
746	</div>	2186	</div>
747	</div></body>	2187	</div></body>
748	</html>	2188	</html>

Diff Legend

-–
+Removed lines
-+
+Added lines
-<
+Changed lines
->
+Changed lines

Comparing libev/ev.html (file contents): Revision 1.12 by root, Mon Nov 12 08:35:18 2007 UTC vs. Revision 1.57 by root, Wed Nov 28 11:27:29 2007 UTC

Diff Legend

Comparing libev/ev.html (file contents):
Revision 1.12 by root, Mon Nov 12 08:35:18 2007 UTC vs.
Revision 1.57 by root, Wed Nov 28 11:27:29 2007 UTC