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

Comparing libev/ev.html (file contents):
Revision 1.35 by root, Fri Nov 23 16:17:12 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="Fri Nov 23 17:17:04 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>
22	<li><a href="#TIME_REPRESENTATION">TIME REPRESENTATION</a></li>	23	<li><a href="#TIME_REPRESENTATION">TIME REPRESENTATION</a></li>
23	<li><a href="#GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</a></li>	24	<li><a href="#GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</a></li>
24	<li><a href="#FUNCTIONS_CONTROLLING_THE_EVENT_LOOP">FUNCTIONS CONTROLLING THE EVENT LOOP</a></li>	25	<li><a href="#FUNCTIONS_CONTROLLING_THE_EVENT_LOOP">FUNCTIONS CONTROLLING THE EVENT LOOP</a></li>
25	<li><a href="#ANATOMY_OF_A_WATCHER">ANATOMY OF A WATCHER</a>	26	<li><a href="#ANATOMY_OF_A_WATCHER">ANATOMY OF A WATCHER</a>
		27	<ul><li><a href="#GENERIC_WATCHER_FUNCTIONS">GENERIC WATCHER FUNCTIONS</a></li>
26	<ul><li><a href="#ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH">ASSOCIATING CUSTOM DATA WITH A WATCHER</a></li>	28	<li><a href="#ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH">ASSOCIATING CUSTOM DATA WITH A WATCHER</a></li>
27	</ul>	29	</ul>
28	</li>	30	</li>
29	<li><a href="#WATCHER_TYPES">WATCHER TYPES</a>	31	<li><a href="#WATCHER_TYPES">WATCHER TYPES</a>
30	<ul><li><a href="#code_ev_io_code_is_this_file_descrip"><code>ev_io</code> - is this file descriptor readable or writable</a></li>	32	<ul><li><a href="#code_ev_io_code_is_this_file_descrip"><code>ev_io</code> - is this file descriptor readable or writable?</a></li>
31	<li><a href="#code_ev_timer_code_relative_and_opti"><code>ev_timer</code> - relative and optionally recurring timeouts</a></li>	33	<li><a href="#code_ev_timer_code_relative_and_opti"><code>ev_timer</code> - relative and optionally repeating timeouts</a></li>
32	<li><a href="#code_ev_periodic_code_to_cron_or_not"><code>ev_periodic</code> - to cron or not to cron</a></li>	34	<li><a href="#code_ev_periodic_code_to_cron_or_not"><code>ev_periodic</code> - to cron or not to cron?</a></li>
33	<li><a href="#code_ev_signal_code_signal_me_when_a"><code>ev_signal</code> - signal me when a signal gets signalled</a></li>	35	<li><a href="#code_ev_signal_code_signal_me_when_a"><code>ev_signal</code> - signal me when a signal gets signalled!</a></li>
34	<li><a href="#code_ev_child_code_wait_for_pid_stat"><code>ev_child</code> - wait for pid status changes</a></li>	36	<li><a href="#code_ev_child_code_watch_out_for_pro"><code>ev_child</code> - watch out for process status changes</a></li>
		37	<li><a href="#code_ev_stat_code_did_the_file_attri"><code>ev_stat</code> - did the file attributes just change?</a></li>
35	<li><a href="#code_ev_idle_code_when_you_ve_got_no"><code>ev_idle</code> - when you've got nothing better to do</a></li>	38	<li><a href="#code_ev_idle_code_when_you_ve_got_no"><code>ev_idle</code> - when you've got nothing better to do...</a></li>
36	<li><a href="#code_ev_prepare_code_and_code_ev_che"><code>ev_prepare</code> and <code>ev_check</code> - customise your event loop</a></li>	39	<li><a href="#code_ev_prepare_code_and_code_ev_che"><code>ev_prepare</code> and <code>ev_check</code> - customise your event loop!</a></li>
		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>
37	</ul>	42	</ul>
38	</li>	43	</li>
39	<li><a href="#OTHER_FUNCTIONS">OTHER FUNCTIONS</a></li>	44	<li><a href="#OTHER_FUNCTIONS">OTHER FUNCTIONS</a></li>
40	<li><a href="#LIBEVENT_EMULATION">LIBEVENT EMULATION</a></li>	45	<li><a href="#LIBEVENT_EMULATION">LIBEVENT EMULATION</a></li>
41	<li><a href="#C_SUPPORT">C++ SUPPORT</a></li>	46	<li><a href="#C_SUPPORT">C++ SUPPORT</a></li>
		47	<li><a href="#MACRO_MAGIC">MACRO MAGIC</a></li>
		48	<li><a href="#EMBEDDING">EMBEDDING</a>
		49	<ul><li><a href="#FILESETS">FILESETS</a>
		50	<ul><li><a href="#CORE_EVENT_LOOP">CORE EVENT LOOP</a></li>
		51	<li><a href="#LIBEVENT_COMPATIBILITY_API">LIBEVENT COMPATIBILITY API</a></li>
		52	<li><a href="#AUTOCONF_SUPPORT">AUTOCONF SUPPORT</a></li>
		53	</ul>
		54	</li>
		55	<li><a href="#PREPROCESSOR_SYMBOLS_MACROS">PREPROCESSOR SYMBOLS/MACROS</a></li>
		56	<li><a href="#EXAMPLES">EXAMPLES</a></li>
		57	</ul>
		58	</li>
		59	<li><a href="#COMPLEXITIES">COMPLEXITIES</a></li>
42	<li><a href="#AUTHOR">AUTHOR</a>	60	<li><a href="#AUTHOR">AUTHOR</a>
43	</li>	61	</li>
44	</ul><hr />	62	</ul><hr />
45	<!-- INDEX END -->	63	<!-- INDEX END -->
46		64
47	<h1 id="NAME">NAME</h1><p><a href="#TOP" class="toplink">Top</a></p>	65	<h1 id="NAME">NAME</h1>
48	<div id="NAME_CONTENT">	66	<div id="NAME_CONTENT">
49	<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>
50		68
51	</div>	69	</div>
52	<h1 id="SYNOPSIS">SYNOPSIS</h1><p><a href="#TOP" class="toplink">Top</a></p>	70	<h1 id="SYNOPSIS">SYNOPSIS</h1>
53	<div id="SYNOPSIS_CONTENT">	71	<div id="SYNOPSIS_CONTENT">
54	<pre> #include <ev.h>	72	<pre> #include <ev.h>
55		73
56	</pre>	74	</pre>
57		75
58	</div>	76	</div>
59	<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>
60	<div id="DESCRIPTION_CONTENT">	123	<div id="DESCRIPTION_CONTENT">
61	<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
62	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
63	these event sources and provide your program with events.</p>	126	these event sources and provide your program with events.</p>
64	<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
…		…
68	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
69	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
70	watcher.</p>	133	watcher.</p>
71		134
72	</div>	135	</div>
73	<h1 id="FEATURES">FEATURES</h1><p><a href="#TOP" class="toplink">Top</a></p>	136	<h1 id="FEATURES">FEATURES</h1>
74	<div id="FEATURES_CONTENT">	137	<div id="FEATURES_CONTENT">
75	<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
76	kqueue mechanisms for file descriptor events, relative timers, absolute	139	bsd-specific <code>kqueue</code> and the solaris-specific event port mechanisms
77	timers with customised rescheduling, signal events, process status change	140	for file descriptor events (<code>ev_io</code>), relative timers (<code>ev_timer</code>),
78	events (related to SIGCHLD), and event watchers dealing with the event	141	absolute timers with customised rescheduling (<code>ev_periodic</code>), synchronous
79	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
80	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
81	it to libevent for example).</p>	149	for example).</p>
82		150
83	</div>	151	</div>
84	<h1 id="CONVENTIONS">CONVENTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p>	152	<h1 id="CONVENTIONS">CONVENTIONS</h1>
85	<div id="CONVENTIONS_CONTENT">	153	<div id="CONVENTIONS_CONTENT">
86	<p>Libev is very configurable. In this manual the default configuration	154	<p>Libev is very configurable. In this manual the default configuration will
87	will be described, which supports multiple event loops. For more info	155	be described, which supports multiple event loops. For more info about
88	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
89	<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
90	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>
91	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>
92	will not have this argument.</p>
93		160
94	</div>	161	</div>
95	<h1 id="TIME_REPRESENTATION">TIME REPRESENTATION</h1><p><a href="#TOP" class="toplink">Top</a></p>	162	<h1 id="TIME_REPRESENTATION">TIME REPRESENTATION</h1>
96	<div id="TIME_REPRESENTATION_CONTENT">	163	<div id="TIME_REPRESENTATION_CONTENT">
97	<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
98	(fractional) number of seconds since the (POSIX) epoch (somewhere near	165	(fractional) number of seconds since the (POSIX) epoch (somewhere near
99	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
100	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
101	to the <code>double</code> type in C, and when you need to do any calculations on	168	to the <code>double</code> type in C, and when you need to do any calculations on
102	it, you should treat it as such.</p>	169	it, you should treat it as such.</p>
103		170
104
105
106
107
108	</div>	171	</div>
109	<h1 id="GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p>	172	<h1 id="GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</h1>
110	<div id="GLOBAL_FUNCTIONS_CONTENT">	173	<div id="GLOBAL_FUNCTIONS_CONTENT">
111	<p>These functions can be called anytime, even before initialising the	174	<p>These functions can be called anytime, even before initialising the
112	library in any way.</p>	175	library in any way.</p>
113	<dl>	176	<dl>
114	<dt>ev_tstamp ev_time ()</dt>	177	<dt>ev_tstamp ev_time ()</dt>
…		…
127	version of the library your program was compiled against.</p>	190	version of the library your program was compiled against.</p>
128	<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,
129	as this indicates an incompatible change. Minor versions are usually	192	as this indicates an incompatible change. Minor versions are usually
130	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
131	not a problem.</p>	194	not a problem.</p>
132	<p>Example: make sure we haven't accidentally been linked against the wrong	195	<p>Example: Make sure we haven't accidentally been linked against the wrong
133	version:</p>	196	version.</p>
134	<pre> assert (("libev version mismatch",	197	<pre> assert (("libev version mismatch",
135	ev_version_major () == EV_VERSION_MAJOR	198	ev_version_major () == EV_VERSION_MAJOR
136	&& ev_version_minor () >= EV_VERSION_MINOR));	199	&& ev_version_minor () >= EV_VERSION_MINOR));
137		200
138	</pre>	201	</pre>
…		…
157	returned by <code>ev_supported_backends</code>, as for example kqueue is broken on	220	returned by <code>ev_supported_backends</code>, as for example kqueue is broken on
158	most BSDs and will not be autodetected unless you explicitly request it	221	most BSDs and will not be autodetected unless you explicitly request it
159	(assuming you know what you are doing). This is the set of backends that	222	(assuming you know what you are doing). This is the set of backends that
160	libev will probe for if you specify no backends explicitly.</p>	223	libev will probe for if you specify no backends explicitly.</p>
161	</dd>	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>
162	<dt>ev_set_allocator (void (cb)(void *ptr, long size))</dt>	234	<dt>ev_set_allocator (void (cb)(void *ptr, size_t size))</dt>
163	<dd>	235	<dd>
164	<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
165	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
166	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
167	needs to be allocated, the library might abort or take some potentially	239	allocated, the library might abort or take some potentially destructive
168	destructive action. The default is your system realloc function.</p>	240	action. The default is your system realloc function.</p>
169	<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,
170	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,
171	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>
172	<p>Example: replace the libev allocator with one that waits a bit and then	244	<p>Example: Replace the libev allocator with one that waits a bit and then
173	retries: better than mine).</p>	245	retries).</p>
174	<pre> static void *	246	<pre> static void *
175	persistent_realloc (void *ptr, long size)	247	persistent_realloc (void *ptr, size_t size)
176	{	248	{
177	for (;;)	249	for (;;)
178	{	250	{
179	void *newptr = realloc (ptr, size);	251	void *newptr = realloc (ptr, size);
180		252
…		…
197	indicating the system call or subsystem causing the problem. If this	269	indicating the system call or subsystem causing the problem. If this
198	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
199	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
200	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
201	(such as abort).</p>	273	(such as abort).</p>
202	<p>Example: do the same thing as libev does internally:</p>	274	<p>Example: This is basically the same thing that libev does internally, too.</p>
203	<pre> static void	275	<pre> static void
204	fatal_error (const char *msg)	276	fatal_error (const char *msg)
205	{	277	{
206	perror (msg);	278	perror (msg);
207	abort ();	279	abort ();
…		…
213	</pre>	285	</pre>
214	</dd>	286	</dd>
215	</dl>	287	</dl>
216		288
217	</div>	289	</div>
218	<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>
219	<div id="FUNCTIONS_CONTROLLING_THE_EVENT_LOOP-2">	291	<div id="FUNCTIONS_CONTROLLING_THE_EVENT_LOOP-2">
220	<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
221	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
222	events, and dynamically created loops which do not.</p>	294	events, and dynamically created loops which do not.</p>
223	<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
…		…
343	<dd>	415	<dd>
344	<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
345	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
346	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
347	undefined behaviour (or a failed assertion if assertions are enabled).</p>	419	undefined behaviour (or a failed assertion if assertions are enabled).</p>
348	<p>Example: try to create a event loop that uses epoll and nothing else.</p>	420	<p>Example: Try to create a event loop that uses epoll and nothing else.</p>
349	<pre> struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL \| EVFLAG_NOENV);	421	<pre> struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL \| EVFLAG_NOENV);
350	if (!epoller)	422	if (!epoller)
351	fatal ("no epoll found here, maybe it hides under your chair");	423	fatal ("no epoll found here, maybe it hides under your chair");
352		424
353	</pre>	425	</pre>
354	</dd>	426	</dd>
355	<dt>ev_default_destroy ()</dt>	427	<dt>ev_default_destroy ()</dt>
356	<dd>	428	<dd>
357	<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
358	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
359	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>
360	</dd>	436	</dd>
361	<dt>ev_loop_destroy (loop)</dt>	437	<dt>ev_loop_destroy (loop)</dt>
362	<dd>	438	<dd>
363	<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
364	earlier call to <code>ev_loop_new</code>.</p>	440	earlier call to <code>ev_loop_new</code>.</p>
…		…
442	be handled here by queueing them when their watcher gets executed.	518	be handled here by queueing them when their watcher gets executed.
443	- If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK	519	- If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK
444	were used, return, otherwise continue with step *.	520	were used, return, otherwise continue with step *.
445		521
446	</pre>	522	</pre>
447	<p>Example: queue some jobs and then loop until no events are outsanding	523	<p>Example: Queue some jobs and then loop until no events are outsanding
448	anymore.</p>	524	anymore.</p>
449	<pre> ... queue jobs here, make sure they register event watchers as long	525	<pre> ... queue jobs here, make sure they register event watchers as long
450	... as they still have work to do (even an idle watcher will do..)	526	... as they still have work to do (even an idle watcher will do..)
451	ev_loop (my_loop, 0);	527	ev_loop (my_loop, 0);
452	... jobs done. yeah!	528	... jobs done. yeah!
…		…
471	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
472	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
473	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
474	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
475	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>
476	<p>Example: create a signal watcher, but keep it from keeping <code>ev_loop</code>	552	<p>Example: Create a signal watcher, but keep it from keeping <code>ev_loop</code>
477	running when nothing else is active.</p>	553	running when nothing else is active.</p>
478	<pre> struct dv_signal exitsig;	554	<pre> struct ev_signal exitsig;
479	ev_signal_init (&exitsig, sig_cb, SIGINT);	555	ev_signal_init (&exitsig, sig_cb, SIGINT);
480	ev_signal_start (myloop, &exitsig);	556	ev_signal_start (loop, &exitsig);
481	evf_unref (myloop);	557	evf_unref (loop);
482		558
483	</pre>	559	</pre>
484	<p>Example: for some weird reason, unregister the above signal handler again.</p>	560	<p>Example: For some weird reason, unregister the above signal handler again.</p>
485	<pre> ev_ref (myloop);	561	<pre> ev_ref (loop);
486	ev_signal_stop (myloop, &exitsig);	562	ev_signal_stop (loop, &exitsig);
487		563
488	</pre>	564	</pre>
489	</dd>	565	</dd>
490	</dl>	566	</dl>
491		567
		568
		569
		570
		571
492	</div>	572	</div>
493	<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>
494	<div id="ANATOMY_OF_A_WATCHER_CONTENT">	574	<div id="ANATOMY_OF_A_WATCHER_CONTENT">
495	<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
496	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
497	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>
498	<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)
…		…
525	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
526	*)</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
527	corresponding stop function (<code>ev_<type>_stop (loop, watcher *)</code>.</p>	607	corresponding stop function (<code>ev_<type>_stop (loop, watcher *)</code>.</p>
528	<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
529	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
530	reinitialise it or call its set macro.</p>	610	reinitialise it or call its <code>set</code> macro.</p>
531	<p>You can check whether an event is active by calling the <code>ev_is_active
532	(watcher *)</code> macro. To see whether an event is outstanding (but the
533	callback for it has not been called yet) you can use the <code>ev_is_pending
534	(watcher *)</code> macro.</p>
535	<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
536	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
537	third argument.</p>	613	third argument.</p>
538	<p>The received events usually include a single bit per event type received	614	<p>The received events usually include a single bit per event type received
539	(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
…		…
559	</dd>	635	</dd>
560	<dt><code>EV_CHILD</code></dt>	636	<dt><code>EV_CHILD</code></dt>
561	<dd>	637	<dd>
562	<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>
563	</dd>	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>
		643	</dd>
564	<dt><code>EV_IDLE</code></dt>	644	<dt><code>EV_IDLE</code></dt>
565	<dd>	645	<dd>
566	<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>
567	</dd>	647	</dd>
568	<dt><code>EV_PREPARE</code></dt>	648	<dt><code>EV_PREPARE</code></dt>
…		…
573	<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
574	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
575	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
576	(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
577	<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>
578	</dd>	667	</dd>
579	<dt><code>EV_ERROR</code></dt>	668	<dt><code>EV_ERROR</code></dt>
580	<dd>	669	<dd>
581	<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
582	happen because the watcher could not be properly started because libev	671	happen because the watcher could not be properly started because libev
…		…
590	programs, though, so beware.</p>	679	programs, though, so beware.</p>
591	</dd>	680	</dd>
592	</dl>	681	</dl>
593		682
594	</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>
595	<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>
596	<div id="ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH-2">	763	<div id="ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH-2">
597	<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
598	and read at any time, libev will completely ignore it. This can be used	765	and read at any time, libev will completely ignore it. This can be used
599	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
…		…
616	struct my_io w = (struct my_io )w_;	783	struct my_io w = (struct my_io )w_;
617	...	784	...
618	}	785	}
619		786
620	</pre>	787	</pre>
621	<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
622	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	}
623		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>
624		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	}
625		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	}
626		817
627		818
		819
		820
		821	</pre>
		822
628	</div>	823	</div>
629	<h1 id="WATCHER_TYPES">WATCHER TYPES</h1><p><a href="#TOP" class="toplink">Top</a></p>	824	<h1 id="WATCHER_TYPES">WATCHER TYPES</h1>
630	<div id="WATCHER_TYPES_CONTENT">	825	<div id="WATCHER_TYPES_CONTENT">
631	<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
632	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>
633		837
634		838
635		839
636		840
637		841
638	</div>	842	</div>
639	<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>
640	<div id="code_ev_io_code_is_this_file_descrip-2">	844	<div id="code_ev_io_code_is_this_file_descrip-2">
641	<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
642	in each iteration of the event loop (This behaviour is called	846	in each iteration of the event loop, or, more precisely, when reading
643	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
644	condition persists. Remember you can stop the watcher if you don't want to	848	some data. This behaviour is called level-triggering because you keep
645	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>
646	<p>In general you can register as many read and/or write event watchers per	852	<p>In general you can register as many read and/or write event watchers per
647	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
648	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
649	required if you know what you are doing).</p>	855	required if you know what you are doing).</p>
650	<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
651	(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
652	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
653	to the same underlying file/socket etc. description (that is, they share	859	to the same underlying file/socket/etc. description (that is, they share
654	the same underlying "file open").</p>	860	the same underlying "file open").</p>
655	<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
656	(at the time of this writing, this includes only <code>EVBACKEND_SELECT</code> and	862	(at the time of this writing, this includes only <code>EVBACKEND_SELECT</code> and
657	<code>EVBACKEND_POLL</code>).</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>
658	<dl>	877	<dl>
659	<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>
660	<dt>ev_io_set (ev_io *, int fd, int events)</dt>	879	<dt>ev_io_set (ev_io *, int fd, int events)</dt>
661	<dd>	880	<dd>
662	<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
663	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
664	EV_WRITE</code> to receive the given events.</p>	883	<code>EV_READ \| EV_WRITE</code> to receive the given events.</p>
665	<p>Please note that most of the more scalable backend mechanisms (for example	884	</dd>
666	epoll and solaris ports) can result in spurious readyness notifications	885	<dt>int fd [read-only]</dt>
667	for file descriptors, so you practically need to use non-blocking I/O (and	886	<dd>
668	treat callback invocation as hint only), or retest separately with a safe	887	<p>The file descriptor being watched.</p>
669	interface before doing I/O (XLib can do this), or force the use of either	888	</dd>
670	<code>EVBACKEND_SELECT</code> or <code>EVBACKEND_POLL</code>, which don't suffer from this	889	<dt>int events [read-only]</dt>
671	problem. Also note that it is quite easy to have your callback invoked	890	<dd>
672	when the readyness condition is no longer valid even when employing	891	<p>The events being watched.</p>
673	typical ways of handling events, so its a good idea to use non-blocking
674	I/O unconditionally.</p>
675	</dd>	892	</dd>
676	</dl>	893	</dl>
677	<p>Example: call <code>stdin_readable_cb</code> when STDIN_FILENO has become, well	894	<p>Example: Call <code>stdin_readable_cb</code> when STDIN_FILENO has become, well
678	readable, but only once. Since it is likely line-buffered, you could	895	readable, but only once. Since it is likely line-buffered, you could
679	attempt to read a whole line in the callback:</p>	896	attempt to read a whole line in the callback.</p>
680	<pre> static void	897	<pre> static void
681	stdin_readable_cb (struct ev_loop loop, struct ev_io w, int revents)	898	stdin_readable_cb (struct ev_loop loop, struct ev_io w, int revents)
682	{	899	{
683	ev_io_stop (loop, w);	900	ev_io_stop (loop, w);
684	.. read from stdin here (or from w->fd) and haqndle any I/O errors	901	.. read from stdin here (or from w->fd) and haqndle any I/O errors
…		…
695		912
696		913
697	</pre>	914	</pre>
698		915
699	</div>	916	</div>
700	<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>
701	<div id="code_ev_timer_code_relative_and_opti-2">	918	<div id="code_ev_timer_code_relative_and_opti-2">
702	<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
703	given time, and optionally repeating in regular intervals after that.</p>	920	given time, and optionally repeating in regular intervals after that.</p>
704	<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
705	times out after an hour and you reset your system clock to last years	922	times out after an hour and you reset your system clock to last years
…		…
737	repeating. The exact semantics are:</p>	954	repeating. The exact semantics are:</p>
738	<p>If the timer is started but nonrepeating, stop it.</p>	955	<p>If the timer is started but nonrepeating, stop it.</p>
739	<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
740	value), or reset the running timer to the repeat value.</p>	957	value), or reset the running timer to the repeat value.</p>
741	<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
742	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
743	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,
744	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
745	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
746	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
747	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
748	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>
749	</dd>	987	</dd>
750	</dl>	988	</dl>
751	<p>Example: create a timer that fires after 60 seconds.</p>	989	<p>Example: Create a timer that fires after 60 seconds.</p>
752	<pre> static void	990	<pre> static void
753	one_minute_cb (struct ev_loop loop, struct ev_timer w, int revents)	991	one_minute_cb (struct ev_loop loop, struct ev_timer w, int revents)
754	{	992	{
755	.. one minute over, w is actually stopped right here	993	.. one minute over, w is actually stopped right here
756	}	994	}
…		…
758	struct ev_timer mytimer;	996	struct ev_timer mytimer;
759	ev_timer_init (&mytimer, one_minute_cb, 60., 0.);	997	ev_timer_init (&mytimer, one_minute_cb, 60., 0.);
760	ev_timer_start (loop, &mytimer);	998	ev_timer_start (loop, &mytimer);
761		999
762	</pre>	1000	</pre>
763	<p>Example: create a timeout timer that times out after 10 seconds of	1001	<p>Example: Create a timeout timer that times out after 10 seconds of
764	inactivity.</p>	1002	inactivity.</p>
765	<pre> static void	1003	<pre> static void
766	timeout_cb (struct ev_loop loop, struct ev_timer w, int revents)	1004	timeout_cb (struct ev_loop loop, struct ev_timer w, int revents)
767	{	1005	{
768	.. ten seconds without any activity	1006	.. ten seconds without any activity
…		…
781		1019
782		1020
783	</pre>	1021	</pre>
784		1022
785	</div>	1023	</div>
786	<h2 id="code_ev_periodic_code_to_cron_or_not"><code>ev_periodic</code> - to cron or not to cron</h2>	1024	<h2 id="code_ev_periodic_code_to_cron_or_not"><code>ev_periodic</code> - to cron or not to cron?</h2>
787	<div id="code_ev_periodic_code_to_cron_or_not-2">	1025	<div id="code_ev_periodic_code_to_cron_or_not-2">
788	<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
789	(and unfortunately a bit complex).</p>	1027	(and unfortunately a bit complex).</p>
790	<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)
791	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
792	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
793	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 ()
794	+ 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
795	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
796	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
797	again).</p>	1035	again).</p>
798	<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
799	triggering an event on eahc midnight, local time.</p>	1037	triggering an event on eahc midnight, local time.</p>
…		…
871	<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
872	when you changed some parameters or the reschedule callback would return	1110	when you changed some parameters or the reschedule callback would return
873	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
874	program when the crontabs have changed).</p>	1112	program when the crontabs have changed).</p>
875	</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>
876	</dl>	1126	</dl>
877	<p>Example: call a callback every hour, or, more precisely, whenever the	1127	<p>Example: Call a callback every hour, or, more precisely, whenever the
878	system clock is divisible by 3600. The callback invocation times have	1128	system clock is divisible by 3600. The callback invocation times have
879	potentially a lot of jittering, but good long-term stability.</p>	1129	potentially a lot of jittering, but good long-term stability.</p>
880	<pre> static void	1130	<pre> static void
881	clock_cb (struct ev_loop loop, struct ev_io w, int revents)	1131	clock_cb (struct ev_loop loop, struct ev_io w, int revents)
882	{	1132	{
…		…
886	struct ev_periodic hourly_tick;	1136	struct ev_periodic hourly_tick;
887	ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);	1137	ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);
888	ev_periodic_start (loop, &hourly_tick);	1138	ev_periodic_start (loop, &hourly_tick);
889		1139
890	</pre>	1140	</pre>
891	<p>Example: the same as above, but use a reschedule callback to do it:</p>	1141	<p>Example: The same as above, but use a reschedule callback to do it:</p>
892	<pre> #include <math.h>	1142	<pre> #include <math.h>
893		1143
894	static ev_tstamp	1144	static ev_tstamp
895	my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)	1145	my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)
896	{	1146	{
…		…
898	}	1148	}
899		1149
900	ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);	1150	ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);
901		1151
902	</pre>	1152	</pre>
903	<p>Example: call a callback every hour, starting now:</p>	1153	<p>Example: Call a callback every hour, starting now:</p>
904	<pre> struct ev_periodic hourly_tick;	1154	<pre> struct ev_periodic hourly_tick;
905	ev_periodic_init (&hourly_tick, clock_cb,	1155	ev_periodic_init (&hourly_tick, clock_cb,
906	fmod (ev_now (loop), 3600.), 3600., 0);	1156	fmod (ev_now (loop), 3600.), 3600., 0);
907	ev_periodic_start (loop, &hourly_tick);	1157	ev_periodic_start (loop, &hourly_tick);
908		1158
…		…
910		1160
911		1161
912	</pre>	1162	</pre>
913		1163
914	</div>	1164	</div>
915	<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>
916	<div id="code_ev_signal_code_signal_me_when_a-2">	1166	<div id="code_ev_signal_code_signal_me_when_a-2">
917	<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
918	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
919	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
920	normal event processing, like any other event.</p>	1170	normal event processing, like any other event.</p>
…		…
929	<dt>ev_signal_set (ev_signal *, int signum)</dt>	1179	<dt>ev_signal_set (ev_signal *, int signum)</dt>
930	<dd>	1180	<dd>
931	<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
932	of the <code>SIGxxx</code> constants).</p>	1182	of the <code>SIGxxx</code> constants).</p>
933	</dd>	1183	</dd>
		1184	<dt>int signum [read-only]</dt>
		1185	<dd>
		1186	<p>The signal the watcher watches out for.</p>
		1187	</dd>
934	</dl>	1188	</dl>
935		1189
		1190
		1191
		1192
		1193
936	</div>	1194	</div>
937	<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>
938	<div id="code_ev_child_code_wait_for_pid_stat-2">	1196	<div id="code_ev_child_code_watch_out_for_pro-2">
939	<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
940	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>
941	<dl>	1199	<dl>
942	<dt>ev_child_init (ev_child *, callback, int pid)</dt>	1200	<dt>ev_child_init (ev_child *, callback, int pid)</dt>
943	<dt>ev_child_set (ev_child *, int pid)</dt>	1201	<dt>ev_child_set (ev_child *, int pid)</dt>
…		…
947	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
948	the status word (use the macros from <code>sys/wait.h</code> and see your systems	1206	the status word (use the macros from <code>sys/wait.h</code> and see your systems
949	<code>waitpid</code> documentation). The <code>rpid</code> member contains the pid of the	1207	<code>waitpid</code> documentation). The <code>rpid</code> member contains the pid of the
950	process causing the status change.</p>	1208	process causing the status change.</p>
951	</dd>	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>
		1222	</dd>
952	</dl>	1223	</dl>
953	<p>Example: try to exit cleanly on SIGINT and SIGTERM.</p>	1224	<p>Example: Try to exit cleanly on SIGINT and SIGTERM.</p>
954	<pre> static void	1225	<pre> static void
955	sigint_cb (struct ev_loop loop, struct ev_signal w, int revents)	1226	sigint_cb (struct ev_loop loop, struct ev_signal w, int revents)
956	{	1227	{
957	ev_unloop (loop, EVUNLOOP_ALL);	1228	ev_unloop (loop, EVUNLOOP_ALL);
958	}	1229	}
…		…
965		1236
966		1237
967	</pre>	1238	</pre>
968		1239
969	</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>
970	<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>
971	<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">
972	<p>Idle watchers trigger events when there are no other events are pending	1341	<p>Idle watchers trigger events when there are no other events are pending
973	(prepare, check and other idle watchers do not count). That is, as long	1342	(prepare, check and other idle watchers do not count). That is, as long
974	as your process is busy handling sockets or timeouts (or even signals,	1343	as your process is busy handling sockets or timeouts (or even signals,
975	imagine) it will not be triggered. But when your process is idle all idle	1344	imagine) it will not be triggered. But when your process is idle all idle
…		…
988	<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
989	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,
990	believe me.</p>	1359	believe me.</p>
991	</dd>	1360	</dd>
992	</dl>	1361	</dl>
993	<p>Example: dynamically allocate an <code>ev_idle</code>, start it, and in the	1362	<p>Example: Dynamically allocate an <code>ev_idle</code> watcher, start it, and in the
994	callback, free it. Alos, use no error checking, as usual.</p>	1363	callback, free it. Also, use no error checking, as usual.</p>
995	<pre> static void	1364	<pre> static void
996	idle_cb (struct ev_loop loop, struct ev_idle w, int revents)	1365	idle_cb (struct ev_loop loop, struct ev_idle w, int revents)
997	{	1366	{
998	free (w);	1367	free (w);
999	// now do something you wanted to do when the program has	1368	// now do something you wanted to do when the program has
…		…
1008		1377
1009		1378
1010	</pre>	1379	</pre>
1011		1380
1012	</div>	1381	</div>
1013	<h2 id="code_ev_prepare_code_and_code_ev_che"><code>ev_prepare</code> and <code>ev_check</code> - customise your 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>
1014	<div id="code_ev_prepare_code_and_code_ev_che-2">	1383	<div id="code_ev_prepare_code_and_code_ev_che-2">
1015	<p>Prepare and check watchers are usually (but not always) used in tandem:	1384	<p>Prepare and check watchers are usually (but not always) used in tandem:
1016	prepare watchers get invoked before the process blocks and check watchers	1385	prepare watchers get invoked before the process blocks and check watchers
1017	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>
1018	<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
1019	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
1020	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>
1021	<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
1022	to be watched by the other library, registering <code>ev_io</code> watchers for	1402	to be watched by the other library, registering <code>ev_io</code> watchers for
1023	them and starting an <code>ev_timer</code> watcher for any timeouts (many libraries	1403	them and starting an <code>ev_timer</code> watcher for any timeouts (many libraries
1024	provide just this functionality). Then, in the check watcher you check for	1404	provide just this functionality). Then, in the check watcher you check for
1025	any events that occured (by checking the pending status of all watchers	1405	any events that occured (by checking the pending status of all watchers
…		…
1041	<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
1042	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>
1043	macros, but using them is utterly, utterly and completely pointless.</p>	1423	macros, but using them is utterly, utterly and completely pointless.</p>
1044	</dd>	1424	</dd>
1045	</dl>	1425	</dl>
1046	<p>Example: TODO.</p>	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;
1047		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	}
1048		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 ()));
1049		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);
1050		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)));
1051		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
1052	</div>	1485	</div>
1053	<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>
1054	<div id="OTHER_FUNCTIONS_CONTENT">	1599	<div id="OTHER_FUNCTIONS_CONTENT">
1055	<p>There are some other functions of possible interest. Described. Here. Now.</p>	1600	<p>There are some other functions of possible interest. Described. Here. Now.</p>
1056	<dl>	1601	<dl>
1057	<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>
1058	<dd>	1603	<dd>
…		…
1082		1627
1083	ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);	1628	ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);
1084		1629
1085	</pre>	1630	</pre>
1086	</dd>	1631	</dd>
1087	<dt>ev_feed_event (loop, watcher, int events)</dt>	1632	<dt>ev_feed_event (ev_loop , watcher , int revents)</dt>
1088	<dd>	1633	<dd>
1089	<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
1090	had 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
1091	initialised but not necessarily started event watcher).</p>	1636	initialised but not necessarily started event watcher).</p>
1092	</dd>	1637	</dd>
1093	<dt>ev_feed_fd_event (loop, int fd, int revents)</dt>	1638	<dt>ev_feed_fd_event (ev_loop *, int fd, int revents)</dt>
1094	<dd>	1639	<dd>
1095	<p>Feed an event on the given fd, as if a file descriptor backend detected	1640	<p>Feed an event on the given fd, as if a file descriptor backend detected
1096	the given events it.</p>	1641	the given events it.</p>
1097	</dd>	1642	</dd>
1098	<dt>ev_feed_signal_event (loop, int signum)</dt>	1643	<dt>ev_feed_signal_event (ev_loop *loop, int signum)</dt>
1099	<dd>	1644	<dd>
1100	<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>
1101	</dd>	1647	</dd>
1102	</dl>	1648	</dl>
1103		1649
1104		1650
1105		1651
1106		1652
1107		1653
1108	</div>	1654	</div>
1109	<h1 id="LIBEVENT_EMULATION">LIBEVENT EMULATION</h1><p><a href="#TOP" class="toplink">Top</a></p>	1655	<h1 id="LIBEVENT_EMULATION">LIBEVENT EMULATION</h1>
1110	<div id="LIBEVENT_EMULATION_CONTENT">	1656	<div id="LIBEVENT_EMULATION_CONTENT">
1111	<p>Libev offers a compatibility emulation layer for libevent. It cannot	1657	<p>Libev offers a compatibility emulation layer for libevent. It cannot
1112	emulate the internals of libevent, so here are some usage hints:</p>	1658	emulate the internals of libevent, so here are some usage hints:</p>
1113	<dl>	1659	<dl>
1114	<dt>* Use it by including <event.h>, as usual.</dt>	1660	<dt>* Use it by including <event.h>, as usual.</dt>
…		…
1124	<dt>* The libev emulation is <i>not</i> ABI compatible to libevent, you need	1670	<dt>* The libev emulation is <i>not</i> ABI compatible to libevent, you need
1125	to use the libev header file and library.</dt>	1671	to use the libev header file and library.</dt>
1126	</dl>	1672	</dl>
1127		1673
1128	</div>	1674	</div>
1129	<h1 id="C_SUPPORT">C++ SUPPORT</h1><p><a href="#TOP" class="toplink">Top</a></p>	1675	<h1 id="C_SUPPORT">C++ SUPPORT</h1>
1130	<div id="C_SUPPORT_CONTENT">	1676	<div id="C_SUPPORT_CONTENT">
1131	<p>TBD.</p>	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>
1132		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
1133	</div>	1779	</div>
1134	<h1 id="AUTHOR">AUTHOR</h1><p><a href="#TOP" class="toplink">Top</a></p>	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>
1135	<div id="AUTHOR_CONTENT">	2183	<div id="AUTHOR_CONTENT">
1136	<p>Marc Lehmann <libev@schmorp.de>.</p>	2184	<p>Marc Lehmann <libev@schmorp.de>.</p>
1137		2185
1138	</div>	2186	</div>
1139	</div></body>	2187	</div></body>
1140	</html>	2188	</html>

Diff Legend

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

Comparing libev/ev.html (file contents): Revision 1.35 by root, Fri Nov 23 16:17:12 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 1.35 by root, Fri Nov 23 16:17:12 2007 UTC vs.
Revision 1.57 by root, Wed Nov 28 11:27:29 2007 UTC