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4	<head>	4	<head>
5	<title>libev</title>	5	<title>libev</title>
6	<meta name="description" content="Pod documentation for libev" />	6	<meta name="description" content="Pod documentation for libev" />
7	<meta name="inputfile" content="<standard input>" />	7	<meta name="inputfile" content="<standard input>" />
8	<meta name="outputfile" content="<standard output>" />	8	<meta name="outputfile" content="<standard output>" />
9	<meta name="created" content="Sat Nov 24 05:58:35 2007" />	9	<meta name="created" content="Tue Nov 27 21:29:04 2007" />
10	<meta name="generator" content="Pod::Xhtml 1.57" />	10	<meta name="generator" content="Pod::Xhtml 1.57" />
11	<link rel="stylesheet" href="http://res.tst.eu/pod.css"/></head>	11	<link rel="stylesheet" href="http://res.tst.eu/pod.css"/></head>
12	<body>	12	<body>
13	<div class="pod">	13	<div class="pod">
14	<!-- INDEX START -->	14	<!-- INDEX START -->
15	<h3 id="TOP">Index</h3>	15	<h3 id="TOP">Index</h3>
16		16
17	<ul><li><a href="#NAME">NAME</a></li>	17	<ul><li><a href="#NAME">NAME</a></li>
18	<li><a href="#SYNOPSIS">SYNOPSIS</a></li>	18	<li><a href="#SYNOPSIS">SYNOPSIS</a></li>
		19	<li><a href="#EXAMPLE_PROGRAM">EXAMPLE PROGRAM</a></li>
19	<li><a href="#DESCRIPTION">DESCRIPTION</a></li>	20	<li><a href="#DESCRIPTION">DESCRIPTION</a></li>
20	<li><a href="#FEATURES">FEATURES</a></li>	21	<li><a href="#FEATURES">FEATURES</a></li>
21	<li><a href="#CONVENTIONS">CONVENTIONS</a></li>	22	<li><a href="#CONVENTIONS">CONVENTIONS</a></li>
22	<li><a href="#TIME_REPRESENTATION">TIME REPRESENTATION</a></li>	23	<li><a href="#TIME_REPRESENTATION">TIME REPRESENTATION</a></li>
23	<li><a href="#GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</a></li>	24	<li><a href="#GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</a></li>
24	<li><a href="#FUNCTIONS_CONTROLLING_THE_EVENT_LOOP">FUNCTIONS CONTROLLING THE EVENT LOOP</a></li>	25	<li><a href="#FUNCTIONS_CONTROLLING_THE_EVENT_LOOP">FUNCTIONS CONTROLLING THE EVENT LOOP</a></li>
25	<li><a href="#ANATOMY_OF_A_WATCHER">ANATOMY OF A WATCHER</a>	26	<li><a href="#ANATOMY_OF_A_WATCHER">ANATOMY OF A WATCHER</a>
		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>
37	<li><a href="#code_ev_embed_code_when_one_backend_"><code>ev_embed</code> - when one backend isn't enough</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>
38	</ul>	42	</ul>
39	</li>	43	</li>
40	<li><a href="#OTHER_FUNCTIONS">OTHER FUNCTIONS</a></li>	44	<li><a href="#OTHER_FUNCTIONS">OTHER FUNCTIONS</a></li>
41	<li><a href="#LIBEVENT_EMULATION">LIBEVENT EMULATION</a></li>	45	<li><a href="#LIBEVENT_EMULATION">LIBEVENT EMULATION</a></li>
42	<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>
43	<li><a href="#AUTHOR">AUTHOR</a>	60	<li><a href="#AUTHOR">AUTHOR</a>
44	</li>	61	</li>
45	</ul><hr />	62	</ul><hr />
46	<!-- INDEX END -->	63	<!-- INDEX END -->
47		64
48	<h1 id="NAME">NAME</h1><p><a href="#TOP" class="toplink">Top</a></p>	65	<h1 id="NAME">NAME</h1>
49	<div id="NAME_CONTENT">	66	<div id="NAME_CONTENT">
50	<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>
51		68
52	</div>	69	</div>
53	<h1 id="SYNOPSIS">SYNOPSIS</h1><p><a href="#TOP" class="toplink">Top</a></p>	70	<h1 id="SYNOPSIS">SYNOPSIS</h1>
54	<div id="SYNOPSIS_CONTENT">	71	<div id="SYNOPSIS_CONTENT">
55	<pre> #include <ev.h>	72	<pre> #include <ev.h>
56		73
57	</pre>	74	</pre>
58		75
59	</div>	76	</div>
60	<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>
61	<div id="DESCRIPTION_CONTENT">	123	<div id="DESCRIPTION_CONTENT">
62	<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
63	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
64	these event sources and provide your program with events.</p>	126	these event sources and provide your program with events.</p>
65	<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
…		…
69	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
70	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
71	watcher.</p>	133	watcher.</p>
72		134
73	</div>	135	</div>
74	<h1 id="FEATURES">FEATURES</h1><p><a href="#TOP" class="toplink">Top</a></p>	136	<h1 id="FEATURES">FEATURES</h1>
75	<div id="FEATURES_CONTENT">	137	<div id="FEATURES_CONTENT">
76	<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
77	kqueue mechanisms for file descriptor events, relative timers, absolute	139	bsd-specific <code>kqueue</code> and the solaris-specific event port mechanisms
78	timers with customised rescheduling, signal events, process status change	140	for file descriptor events (<code>ev_io</code>), relative timers (<code>ev_timer</code>),
79	events (related to SIGCHLD), and event watchers dealing with the event	141	absolute timers with customised rescheduling (<code>ev_periodic</code>), synchronous
80	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
81	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
82	it to libevent for example).</p>	149	for example).</p>
83		150
84	</div>	151	</div>
85	<h1 id="CONVENTIONS">CONVENTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p>	152	<h1 id="CONVENTIONS">CONVENTIONS</h1>
86	<div id="CONVENTIONS_CONTENT">	153	<div id="CONVENTIONS_CONTENT">
87	<p>Libev is very configurable. In this manual the default configuration	154	<p>Libev is very configurable. In this manual the default configuration will
88	will be described, which supports multiple event loops. For more info	155	be described, which supports multiple event loops. For more info about
89	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
90	<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
91	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>
92	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>
93	will not have this argument.</p>
94		160
95	</div>	161	</div>
96	<h1 id="TIME_REPRESENTATION">TIME REPRESENTATION</h1><p><a href="#TOP" class="toplink">Top</a></p>	162	<h1 id="TIME_REPRESENTATION">TIME REPRESENTATION</h1>
97	<div id="TIME_REPRESENTATION_CONTENT">	163	<div id="TIME_REPRESENTATION_CONTENT">
98	<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
99	(fractional) number of seconds since the (POSIX) epoch (somewhere near	165	(fractional) number of seconds since the (POSIX) epoch (somewhere near
100	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
101	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
102	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
103	it, you should treat it as such.</p>	169	it, you should treat it as such.</p>
104		170
105
106
107
108
109	</div>	171	</div>
110	<h1 id="GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p>	172	<h1 id="GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</h1>
111	<div id="GLOBAL_FUNCTIONS_CONTENT">	173	<div id="GLOBAL_FUNCTIONS_CONTENT">
112	<p>These functions can be called anytime, even before initialising the	174	<p>These functions can be called anytime, even before initialising the
113	library in any way.</p>	175	library in any way.</p>
114	<dl>	176	<dl>
115	<dt>ev_tstamp ev_time ()</dt>	177	<dt>ev_tstamp ev_time ()</dt>
…		…
128	version of the library your program was compiled against.</p>	190	version of the library your program was compiled against.</p>
129	<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,
130	as this indicates an incompatible change. Minor versions are usually	192	as this indicates an incompatible change. Minor versions are usually
131	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
132	not a problem.</p>	194	not a problem.</p>
133	<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
134	version:</p>	196	version.</p>
135	<pre> assert (("libev version mismatch",	197	<pre> assert (("libev version mismatch",
136	ev_version_major () == EV_VERSION_MAJOR	198	ev_version_major () == EV_VERSION_MAJOR
137	&& ev_version_minor () >= EV_VERSION_MINOR));	199	&& ev_version_minor () >= EV_VERSION_MINOR));
138		200
139	</pre>	201	</pre>
…		…
167	might be supported on the current system, you would need to look at	229	might be supported on the current system, you would need to look at
168	<code>ev_embeddable_backends () & ev_supported_backends ()</code>, likewise for	230	<code>ev_embeddable_backends () & ev_supported_backends ()</code>, likewise for
169	recommended ones.</p>	231	recommended ones.</p>
170	<p>See the description of <code>ev_embed</code> watchers for more info.</p>	232	<p>See the description of <code>ev_embed</code> watchers for more info.</p>
171	</dd>	233	</dd>
172	<dt>ev_set_allocator (void (cb)(void *ptr, long size))</dt>	234	<dt>ev_set_allocator (void (cb)(void *ptr, size_t size))</dt>
173	<dd>	235	<dd>
174	<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
175	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
176	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
177	needs to be allocated, the library might abort or take some potentially	239	allocated, the library might abort or take some potentially destructive
178	destructive action. The default is your system realloc function.</p>	240	action. The default is your system realloc function.</p>
179	<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,
180	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,
181	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>
182	<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
183	retries: better than mine).</p>	245	retries).</p>
184	<pre> static void *	246	<pre> static void *
185	persistent_realloc (void *ptr, long size)	247	persistent_realloc (void *ptr, size_t size)
186	{	248	{
187	for (;;)	249	for (;;)
188	{	250	{
189	void *newptr = realloc (ptr, size);	251	void *newptr = realloc (ptr, size);
190		252
…		…
207	indicating the system call or subsystem causing the problem. If this	269	indicating the system call or subsystem causing the problem. If this
208	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
209	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
210	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
211	(such as abort).</p>	273	(such as abort).</p>
212	<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>
213	<pre> static void	275	<pre> static void
214	fatal_error (const char *msg)	276	fatal_error (const char *msg)
215	{	277	{
216	perror (msg);	278	perror (msg);
217	abort ();	279	abort ();
…		…
223	</pre>	285	</pre>
224	</dd>	286	</dd>
225	</dl>	287	</dl>
226		288
227	</div>	289	</div>
228	<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>
229	<div id="FUNCTIONS_CONTROLLING_THE_EVENT_LOOP-2">	291	<div id="FUNCTIONS_CONTROLLING_THE_EVENT_LOOP-2">
230	<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
231	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
232	events, and dynamically created loops which do not.</p>	294	events, and dynamically created loops which do not.</p>
233	<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
…		…
353	<dd>	415	<dd>
354	<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
355	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
356	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
357	undefined behaviour (or a failed assertion if assertions are enabled).</p>	419	undefined behaviour (or a failed assertion if assertions are enabled).</p>
358	<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>
359	<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);
360	if (!epoller)	422	if (!epoller)
361	fatal ("no epoll found here, maybe it hides under your chair");	423	fatal ("no epoll found here, maybe it hides under your chair");
362		424
363	</pre>	425	</pre>
364	</dd>	426	</dd>
365	<dt>ev_default_destroy ()</dt>	427	<dt>ev_default_destroy ()</dt>
366	<dd>	428	<dd>
367	<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
368	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
369	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>
370	</dd>	436	</dd>
371	<dt>ev_loop_destroy (loop)</dt>	437	<dt>ev_loop_destroy (loop)</dt>
372	<dd>	438	<dd>
373	<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
374	earlier call to <code>ev_loop_new</code>.</p>	440	earlier call to <code>ev_loop_new</code>.</p>
…		…
452	be handled here by queueing them when their watcher gets executed.	518	be handled here by queueing them when their watcher gets executed.
453	- 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
454	were used, return, otherwise continue with step *.	520	were used, return, otherwise continue with step *.
455		521
456	</pre>	522	</pre>
457	<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
458	anymore.</p>	524	anymore.</p>
459	<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
460	... 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..)
461	ev_loop (my_loop, 0);	527	ev_loop (my_loop, 0);
462	... jobs done. yeah!	528	... jobs done. yeah!
…		…
481	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
482	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
483	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
484	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
485	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>
486	<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>
487	running when nothing else is active.</p>	553	running when nothing else is active.</p>
488	<pre> struct dv_signal exitsig;	554	<pre> struct ev_signal exitsig;
489	ev_signal_init (&exitsig, sig_cb, SIGINT);	555	ev_signal_init (&exitsig, sig_cb, SIGINT);
490	ev_signal_start (myloop, &exitsig);	556	ev_signal_start (loop, &exitsig);
491	evf_unref (myloop);	557	evf_unref (loop);
492		558
493	</pre>	559	</pre>
494	<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>
495	<pre> ev_ref (myloop);	561	<pre> ev_ref (loop);
496	ev_signal_stop (myloop, &exitsig);	562	ev_signal_stop (loop, &exitsig);
497		563
498	</pre>	564	</pre>
499	</dd>	565	</dd>
500	</dl>	566	</dl>
501		567
		568
		569
		570
		571
502	</div>	572	</div>
503	<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>
504	<div id="ANATOMY_OF_A_WATCHER_CONTENT">	574	<div id="ANATOMY_OF_A_WATCHER_CONTENT">
505	<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
506	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
507	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>
508	<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)
…		…
535	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
536	*)</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
537	corresponding stop function (<code>ev_<type>_stop (loop, watcher *)</code>.</p>	607	corresponding stop function (<code>ev_<type>_stop (loop, watcher *)</code>.</p>
538	<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
539	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
540	reinitialise it or call its set macro.</p>	610	reinitialise it or call its <code>set</code> macro.</p>
541	<p>You can check whether an event is active by calling the <code>ev_is_active
542	(watcher *)</code> macro. To see whether an event is outstanding (but the
543	callback for it has not been called yet) you can use the <code>ev_is_pending
544	(watcher *)</code> macro.</p>
545	<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
546	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
547	third argument.</p>	613	third argument.</p>
548	<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
549	(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
…		…
569	</dd>	635	</dd>
570	<dt><code>EV_CHILD</code></dt>	636	<dt><code>EV_CHILD</code></dt>
571	<dd>	637	<dd>
572	<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>
573	</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>
574	<dt><code>EV_IDLE</code></dt>	644	<dt><code>EV_IDLE</code></dt>
575	<dd>	645	<dd>
576	<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>
577	</dd>	647	</dd>
578	<dt><code>EV_PREPARE</code></dt>	648	<dt><code>EV_PREPARE</code></dt>
…		…
583	<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
584	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
585	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
586	(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
587	<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>
588	</dd>	667	</dd>
589	<dt><code>EV_ERROR</code></dt>	668	<dt><code>EV_ERROR</code></dt>
590	<dd>	669	<dd>
591	<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
592	happen because the watcher could not be properly started because libev	671	happen because the watcher could not be properly started because libev
…		…
598	your callbacks is well-written it can just attempt the operation and cope	677	your callbacks is well-written it can just attempt the operation and cope
599	with the error from read() or write(). This will not work in multithreaded	678	with the error from read() or write(). This will not work in multithreaded
600	programs, though, so beware.</p>	679	programs, though, so beware.</p>
601	</dd>	680	</dd>
602	</dl>	681	</dl>
		682
		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
603		760
604	</div>	761	</div>
605	<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>
606	<div id="ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH-2">	763	<div id="ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH-2">
607	<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
…		…
634		791
635		792
636		793
637		794
638	</div>	795	</div>
639	<h1 id="WATCHER_TYPES">WATCHER TYPES</h1><p><a href="#TOP" class="toplink">Top</a></p>	796	<h1 id="WATCHER_TYPES">WATCHER TYPES</h1>
640	<div id="WATCHER_TYPES_CONTENT">	797	<div id="WATCHER_TYPES_CONTENT">
641	<p>This section describes each watcher in detail, but will not repeat	798	<p>This section describes each watcher in detail, but will not repeat
642	information given in the last section.</p>	799	information given in the last section. Any initialisation/set macros,
		800	functions and members specific to the watcher type are explained.</p>
		801	<p>Members are additionally marked with either <i>[read-only]</i>, meaning that,
		802	while the watcher is active, you can look at the member and expect some
		803	sensible content, but you must not modify it (you can modify it while the
		804	watcher is stopped to your hearts content), or <i>[read-write]</i>, which
		805	means you can expect it to have some sensible content while the watcher
		806	is active, but you can also modify it. Modifying it may not do something
		807	sensible or take immediate effect (or do anything at all), but libev will
		808	not crash or malfunction in any way.</p>
643		809
644		810
645		811
646		812
647		813
648	</div>	814	</div>
649	<h2 id="code_ev_io_code_is_this_file_descrip"><code>ev_io</code> - is this file descriptor readable or writable</h2>	815	<h2 id="code_ev_io_code_is_this_file_descrip"><code>ev_io</code> - is this file descriptor readable or writable?</h2>
650	<div id="code_ev_io_code_is_this_file_descrip-2">	816	<div id="code_ev_io_code_is_this_file_descrip-2">
651	<p>I/O watchers check whether a file descriptor is readable or writable	817	<p>I/O watchers check whether a file descriptor is readable or writable
652	in each iteration of the event loop (This behaviour is called	818	in each iteration of the event loop, or, more precisely, when reading
653	level-triggering because you keep receiving events as long as the	819	would not block the process and writing would at least be able to write
654	condition persists. Remember you can stop the watcher if you don't want to	820	some data. This behaviour is called level-triggering because you keep
655	act on the event and neither want to receive future events).</p>	821	receiving events as long as the condition persists. Remember you can stop
		822	the watcher if you don't want to act on the event and neither want to
		823	receive future events.</p>
656	<p>In general you can register as many read and/or write event watchers per	824	<p>In general you can register as many read and/or write event watchers per
657	fd as you want (as long as you don't confuse yourself). Setting all file	825	fd as you want (as long as you don't confuse yourself). Setting all file
658	descriptors to non-blocking mode is also usually a good idea (but not	826	descriptors to non-blocking mode is also usually a good idea (but not
659	required if you know what you are doing).</p>	827	required if you know what you are doing).</p>
660	<p>You have to be careful with dup'ed file descriptors, though. Some backends	828	<p>You have to be careful with dup'ed file descriptors, though. Some backends
661	(the linux epoll backend is a notable example) cannot handle dup'ed file	829	(the linux epoll backend is a notable example) cannot handle dup'ed file
662	descriptors correctly if you register interest in two or more fds pointing	830	descriptors correctly if you register interest in two or more fds pointing
663	to the same underlying file/socket etc. description (that is, they share	831	to the same underlying file/socket/etc. description (that is, they share
664	the same underlying "file open").</p>	832	the same underlying "file open").</p>
665	<p>If you must do this, then force the use of a known-to-be-good backend	833	<p>If you must do this, then force the use of a known-to-be-good backend
666	(at the time of this writing, this includes only <code>EVBACKEND_SELECT</code> and	834	(at the time of this writing, this includes only <code>EVBACKEND_SELECT</code> and
667	<code>EVBACKEND_POLL</code>).</p>	835	<code>EVBACKEND_POLL</code>).</p>
		836	<p>Another thing you have to watch out for is that it is quite easy to
		837	receive "spurious" readyness notifications, that is your callback might
		838	be called with <code>EV_READ</code> but a subsequent <code>read</code>(2) will actually block
		839	because there is no data. Not only are some backends known to create a
		840	lot of those (for example solaris ports), it is very easy to get into
		841	this situation even with a relatively standard program structure. Thus
		842	it is best to always use non-blocking I/O: An extra <code>read</code>(2) returning
		843	<code>EAGAIN</code> is far preferable to a program hanging until some data arrives.</p>
		844	<p>If you cannot run the fd in non-blocking mode (for example you should not
		845	play around with an Xlib connection), then you have to seperately re-test
		846	wether a file descriptor is really ready with a known-to-be good interface
		847	such as poll (fortunately in our Xlib example, Xlib already does this on
		848	its own, so its quite safe to use).</p>
668	<dl>	849	<dl>
669	<dt>ev_io_init (ev_io *, callback, int fd, int events)</dt>	850	<dt>ev_io_init (ev_io *, callback, int fd, int events)</dt>
670	<dt>ev_io_set (ev_io *, int fd, int events)</dt>	851	<dt>ev_io_set (ev_io *, int fd, int events)</dt>
671	<dd>	852	<dd>
672	<p>Configures an <code>ev_io</code> watcher. The fd is the file descriptor to rceeive	853	<p>Configures an <code>ev_io</code> watcher. The <code>fd</code> is the file descriptor to
673	events for and events is either <code>EV_READ</code>, <code>EV_WRITE</code> or <code>EV_READ \|	854	rceeive events for and events is either <code>EV_READ</code>, <code>EV_WRITE</code> or
674	EV_WRITE</code> to receive the given events.</p>	855	<code>EV_READ \| EV_WRITE</code> to receive the given events.</p>
675	<p>Please note that most of the more scalable backend mechanisms (for example	856	</dd>
676	epoll and solaris ports) can result in spurious readyness notifications	857	<dt>int fd [read-only]</dt>
677	for file descriptors, so you practically need to use non-blocking I/O (and	858	<dd>
678	treat callback invocation as hint only), or retest separately with a safe	859	<p>The file descriptor being watched.</p>
679	interface before doing I/O (XLib can do this), or force the use of either	860	</dd>
680	<code>EVBACKEND_SELECT</code> or <code>EVBACKEND_POLL</code>, which don't suffer from this	861	<dt>int events [read-only]</dt>
681	problem. Also note that it is quite easy to have your callback invoked	862	<dd>
682	when the readyness condition is no longer valid even when employing	863	<p>The events being watched.</p>
683	typical ways of handling events, so its a good idea to use non-blocking
684	I/O unconditionally.</p>
685	</dd>	864	</dd>
686	</dl>	865	</dl>
687	<p>Example: call <code>stdin_readable_cb</code> when STDIN_FILENO has become, well	866	<p>Example: Call <code>stdin_readable_cb</code> when STDIN_FILENO has become, well
688	readable, but only once. Since it is likely line-buffered, you could	867	readable, but only once. Since it is likely line-buffered, you could
689	attempt to read a whole line in the callback:</p>	868	attempt to read a whole line in the callback.</p>
690	<pre> static void	869	<pre> static void
691	stdin_readable_cb (struct ev_loop loop, struct ev_io w, int revents)	870	stdin_readable_cb (struct ev_loop loop, struct ev_io w, int revents)
692	{	871	{
693	ev_io_stop (loop, w);	872	ev_io_stop (loop, w);
694	.. read from stdin here (or from w->fd) and haqndle any I/O errors	873	.. read from stdin here (or from w->fd) and haqndle any I/O errors
…		…
705		884
706		885
707	</pre>	886	</pre>
708		887
709	</div>	888	</div>
710	<h2 id="code_ev_timer_code_relative_and_opti"><code>ev_timer</code> - relative and optionally recurring timeouts</h2>	889	<h2 id="code_ev_timer_code_relative_and_opti"><code>ev_timer</code> - relative and optionally repeating timeouts</h2>
711	<div id="code_ev_timer_code_relative_and_opti-2">	890	<div id="code_ev_timer_code_relative_and_opti-2">
712	<p>Timer watchers are simple relative timers that generate an event after a	891	<p>Timer watchers are simple relative timers that generate an event after a
713	given time, and optionally repeating in regular intervals after that.</p>	892	given time, and optionally repeating in regular intervals after that.</p>
714	<p>The timers are based on real time, that is, if you register an event that	893	<p>The timers are based on real time, that is, if you register an event that
715	times out after an hour and you reset your system clock to last years	894	times out after an hour and you reset your system clock to last years
…		…
747	repeating. The exact semantics are:</p>	926	repeating. The exact semantics are:</p>
748	<p>If the timer is started but nonrepeating, stop it.</p>	927	<p>If the timer is started but nonrepeating, stop it.</p>
749	<p>If the timer is repeating, either start it if necessary (with the repeat	928	<p>If the timer is repeating, either start it if necessary (with the repeat
750	value), or reset the running timer to the repeat value.</p>	929	value), or reset the running timer to the repeat value.</p>
751	<p>This sounds a bit complicated, but here is a useful and typical	930	<p>This sounds a bit complicated, but here is a useful and typical
752	example: Imagine you have a tcp connection and you want a so-called idle	931	example: Imagine you have a tcp connection and you want a so-called
753	timeout, that is, you want to be called when there have been, say, 60	932	idle timeout, that is, you want to be called when there have been,
754	seconds of inactivity on the socket. The easiest way to do this is to	933	say, 60 seconds of inactivity on the socket. The easiest way to do
755	configure an <code>ev_timer</code> with after=repeat=60 and calling ev_timer_again each	934	this is to configure an <code>ev_timer</code> with <code>after</code>=<code>repeat</code>=<code>60</code> and calling
756	time you successfully read or write some data. If you go into an idle	935	<code>ev_timer_again</code> each time you successfully read or write some data. If
757	state where you do not expect data to travel on the socket, you can stop	936	you go into an idle state where you do not expect data to travel on the
758	the timer, and again will automatically restart it if need be.</p>	937	socket, you can stop the timer, and again will automatically restart it if
		938	need be.</p>
		939	<p>You can also ignore the <code>after</code> value and <code>ev_timer_start</code> altogether
		940	and only ever use the <code>repeat</code> value:</p>
		941	<pre> ev_timer_init (timer, callback, 0., 5.);
		942	ev_timer_again (loop, timer);
		943	...
		944	timer->again = 17.;
		945	ev_timer_again (loop, timer);
		946	...
		947	timer->again = 10.;
		948	ev_timer_again (loop, timer);
		949
		950	</pre>
		951	<p>This is more efficient then stopping/starting the timer eahc time you want
		952	to modify its timeout value.</p>
		953	</dd>
		954	<dt>ev_tstamp repeat [read-write]</dt>
		955	<dd>
		956	<p>The current <code>repeat</code> value. Will be used each time the watcher times out
		957	or <code>ev_timer_again</code> is called and determines the next timeout (if any),
		958	which is also when any modifications are taken into account.</p>
759	</dd>	959	</dd>
760	</dl>	960	</dl>
761	<p>Example: create a timer that fires after 60 seconds.</p>	961	<p>Example: Create a timer that fires after 60 seconds.</p>
762	<pre> static void	962	<pre> static void
763	one_minute_cb (struct ev_loop loop, struct ev_timer w, int revents)	963	one_minute_cb (struct ev_loop loop, struct ev_timer w, int revents)
764	{	964	{
765	.. one minute over, w is actually stopped right here	965	.. one minute over, w is actually stopped right here
766	}	966	}
…		…
768	struct ev_timer mytimer;	968	struct ev_timer mytimer;
769	ev_timer_init (&mytimer, one_minute_cb, 60., 0.);	969	ev_timer_init (&mytimer, one_minute_cb, 60., 0.);
770	ev_timer_start (loop, &mytimer);	970	ev_timer_start (loop, &mytimer);
771		971
772	</pre>	972	</pre>
773	<p>Example: create a timeout timer that times out after 10 seconds of	973	<p>Example: Create a timeout timer that times out after 10 seconds of
774	inactivity.</p>	974	inactivity.</p>
775	<pre> static void	975	<pre> static void
776	timeout_cb (struct ev_loop loop, struct ev_timer w, int revents)	976	timeout_cb (struct ev_loop loop, struct ev_timer w, int revents)
777	{	977	{
778	.. ten seconds without any activity	978	.. ten seconds without any activity
…		…
791		991
792		992
793	</pre>	993	</pre>
794		994
795	</div>	995	</div>
796	<h2 id="code_ev_periodic_code_to_cron_or_not"><code>ev_periodic</code> - to cron or not to cron</h2>	996	<h2 id="code_ev_periodic_code_to_cron_or_not"><code>ev_periodic</code> - to cron or not to cron?</h2>
797	<div id="code_ev_periodic_code_to_cron_or_not-2">	997	<div id="code_ev_periodic_code_to_cron_or_not-2">
798	<p>Periodic watchers are also timers of a kind, but they are very versatile	998	<p>Periodic watchers are also timers of a kind, but they are very versatile
799	(and unfortunately a bit complex).</p>	999	(and unfortunately a bit complex).</p>
800	<p>Unlike <code>ev_timer</code>'s, they are not based on real time (or relative time)	1000	<p>Unlike <code>ev_timer</code>'s, they are not based on real time (or relative time)
801	but on wallclock time (absolute time). You can tell a periodic watcher	1001	but on wallclock time (absolute time). You can tell a periodic watcher
802	to trigger "at" some specific point in time. For example, if you tell a	1002	to trigger "at" some specific point in time. For example, if you tell a
803	periodic watcher to trigger in 10 seconds (by specifiying e.g. c<ev_now ()	1003	periodic watcher to trigger in 10 seconds (by specifiying e.g. <code>ev_now ()
804	+ 10.>) and then reset your system clock to the last year, then it will	1004	+ 10.</code>) and then reset your system clock to the last year, then it will
805	take a year to trigger the event (unlike an <code>ev_timer</code>, which would trigger	1005	take a year to trigger the event (unlike an <code>ev_timer</code>, which would trigger
806	roughly 10 seconds later and of course not if you reset your system time	1006	roughly 10 seconds later and of course not if you reset your system time
807	again).</p>	1007	again).</p>
808	<p>They can also be used to implement vastly more complex timers, such as	1008	<p>They can also be used to implement vastly more complex timers, such as
809	triggering an event on eahc midnight, local time.</p>	1009	triggering an event on eahc midnight, local time.</p>
…		…
881	<p>Simply stops and restarts the periodic watcher again. This is only useful	1081	<p>Simply stops and restarts the periodic watcher again. This is only useful
882	when you changed some parameters or the reschedule callback would return	1082	when you changed some parameters or the reschedule callback would return
883	a different time than the last time it was called (e.g. in a crond like	1083	a different time than the last time it was called (e.g. in a crond like
884	program when the crontabs have changed).</p>	1084	program when the crontabs have changed).</p>
885	</dd>	1085	</dd>
		1086	<dt>ev_tstamp interval [read-write]</dt>
		1087	<dd>
		1088	<p>The current interval value. Can be modified any time, but changes only
		1089	take effect when the periodic timer fires or <code>ev_periodic_again</code> is being
		1090	called.</p>
		1091	</dd>
		1092	<dt>ev_tstamp (reschedule_cb)(struct ev_periodic w, ev_tstamp now) [read-write]</dt>
		1093	<dd>
		1094	<p>The current reschedule callback, or <code>0</code>, if this functionality is
		1095	switched off. Can be changed any time, but changes only take effect when
		1096	the periodic timer fires or <code>ev_periodic_again</code> is being called.</p>
		1097	</dd>
886	</dl>	1098	</dl>
887	<p>Example: call a callback every hour, or, more precisely, whenever the	1099	<p>Example: Call a callback every hour, or, more precisely, whenever the
888	system clock is divisible by 3600. The callback invocation times have	1100	system clock is divisible by 3600. The callback invocation times have
889	potentially a lot of jittering, but good long-term stability.</p>	1101	potentially a lot of jittering, but good long-term stability.</p>
890	<pre> static void	1102	<pre> static void
891	clock_cb (struct ev_loop loop, struct ev_io w, int revents)	1103	clock_cb (struct ev_loop loop, struct ev_io w, int revents)
892	{	1104	{
…		…
896	struct ev_periodic hourly_tick;	1108	struct ev_periodic hourly_tick;
897	ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);	1109	ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);
898	ev_periodic_start (loop, &hourly_tick);	1110	ev_periodic_start (loop, &hourly_tick);
899		1111
900	</pre>	1112	</pre>
901	<p>Example: the same as above, but use a reschedule callback to do it:</p>	1113	<p>Example: The same as above, but use a reschedule callback to do it:</p>
902	<pre> #include <math.h>	1114	<pre> #include <math.h>
903		1115
904	static ev_tstamp	1116	static ev_tstamp
905	my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)	1117	my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)
906	{	1118	{
…		…
908	}	1120	}
909		1121
910	ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);	1122	ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);
911		1123
912	</pre>	1124	</pre>
913	<p>Example: call a callback every hour, starting now:</p>	1125	<p>Example: Call a callback every hour, starting now:</p>
914	<pre> struct ev_periodic hourly_tick;	1126	<pre> struct ev_periodic hourly_tick;
915	ev_periodic_init (&hourly_tick, clock_cb,	1127	ev_periodic_init (&hourly_tick, clock_cb,
916	fmod (ev_now (loop), 3600.), 3600., 0);	1128	fmod (ev_now (loop), 3600.), 3600., 0);
917	ev_periodic_start (loop, &hourly_tick);	1129	ev_periodic_start (loop, &hourly_tick);
918		1130
…		…
920		1132
921		1133
922	</pre>	1134	</pre>
923		1135
924	</div>	1136	</div>
925	<h2 id="code_ev_signal_code_signal_me_when_a"><code>ev_signal</code> - signal me when a signal gets signalled</h2>	1137	<h2 id="code_ev_signal_code_signal_me_when_a"><code>ev_signal</code> - signal me when a signal gets signalled!</h2>
926	<div id="code_ev_signal_code_signal_me_when_a-2">	1138	<div id="code_ev_signal_code_signal_me_when_a-2">
927	<p>Signal watchers will trigger an event when the process receives a specific	1139	<p>Signal watchers will trigger an event when the process receives a specific
928	signal one or more times. Even though signals are very asynchronous, libev	1140	signal one or more times. Even though signals are very asynchronous, libev
929	will try it's best to deliver signals synchronously, i.e. as part of the	1141	will try it's best to deliver signals synchronously, i.e. as part of the
930	normal event processing, like any other event.</p>	1142	normal event processing, like any other event.</p>
…		…
939	<dt>ev_signal_set (ev_signal *, int signum)</dt>	1151	<dt>ev_signal_set (ev_signal *, int signum)</dt>
940	<dd>	1152	<dd>
941	<p>Configures the watcher to trigger on the given signal number (usually one	1153	<p>Configures the watcher to trigger on the given signal number (usually one
942	of the <code>SIGxxx</code> constants).</p>	1154	of the <code>SIGxxx</code> constants).</p>
943	</dd>	1155	</dd>
		1156	<dt>int signum [read-only]</dt>
		1157	<dd>
		1158	<p>The signal the watcher watches out for.</p>
		1159	</dd>
944	</dl>	1160	</dl>
945		1161
946		1162
947		1163
948		1164
949		1165
950	</div>	1166	</div>
951	<h2 id="code_ev_child_code_wait_for_pid_stat"><code>ev_child</code> - wait for pid status changes</h2>	1167	<h2 id="code_ev_child_code_watch_out_for_pro"><code>ev_child</code> - watch out for process status changes</h2>
952	<div id="code_ev_child_code_wait_for_pid_stat-2">	1168	<div id="code_ev_child_code_watch_out_for_pro-2">
953	<p>Child watchers trigger when your process receives a SIGCHLD in response to	1169	<p>Child watchers trigger when your process receives a SIGCHLD in response to
954	some child status changes (most typically when a child of yours dies).</p>	1170	some child status changes (most typically when a child of yours dies).</p>
955	<dl>	1171	<dl>
956	<dt>ev_child_init (ev_child *, callback, int pid)</dt>	1172	<dt>ev_child_init (ev_child *, callback, int pid)</dt>
957	<dt>ev_child_set (ev_child *, int pid)</dt>	1173	<dt>ev_child_set (ev_child *, int pid)</dt>
…		…
961	at the <code>rstatus</code> member of the <code>ev_child</code> watcher structure to see	1177	at the <code>rstatus</code> member of the <code>ev_child</code> watcher structure to see
962	the status word (use the macros from <code>sys/wait.h</code> and see your systems	1178	the status word (use the macros from <code>sys/wait.h</code> and see your systems
963	<code>waitpid</code> documentation). The <code>rpid</code> member contains the pid of the	1179	<code>waitpid</code> documentation). The <code>rpid</code> member contains the pid of the
964	process causing the status change.</p>	1180	process causing the status change.</p>
965	</dd>	1181	</dd>
		1182	<dt>int pid [read-only]</dt>
		1183	<dd>
		1184	<p>The process id this watcher watches out for, or <code>0</code>, meaning any process id.</p>
		1185	</dd>
		1186	<dt>int rpid [read-write]</dt>
		1187	<dd>
		1188	<p>The process id that detected a status change.</p>
		1189	</dd>
		1190	<dt>int rstatus [read-write]</dt>
		1191	<dd>
		1192	<p>The process exit/trace status caused by <code>rpid</code> (see your systems
		1193	<code>waitpid</code> and <code>sys/wait.h</code> documentation for details).</p>
		1194	</dd>
966	</dl>	1195	</dl>
967	<p>Example: try to exit cleanly on SIGINT and SIGTERM.</p>	1196	<p>Example: Try to exit cleanly on SIGINT and SIGTERM.</p>
968	<pre> static void	1197	<pre> static void
969	sigint_cb (struct ev_loop loop, struct ev_signal w, int revents)	1198	sigint_cb (struct ev_loop loop, struct ev_signal w, int revents)
970	{	1199	{
971	ev_unloop (loop, EVUNLOOP_ALL);	1200	ev_unloop (loop, EVUNLOOP_ALL);
972	}	1201	}
…		…
979		1208
980		1209
981	</pre>	1210	</pre>
982		1211
983	</div>	1212	</div>
		1213	<h2 id="code_ev_stat_code_did_the_file_attri"><code>ev_stat</code> - did the file attributes just change?</h2>
		1214	<div id="code_ev_stat_code_did_the_file_attri-2">
		1215	<p>This watches a filesystem path for attribute changes. That is, it calls
		1216	<code>stat</code> regularly (or when the OS says it changed) and sees if it changed
		1217	compared to the last time, invoking the callback if it did.</p>
		1218	<p>The path does not need to exist: changing from "path exists" to "path does
		1219	not exist" is a status change like any other. The condition "path does
		1220	not exist" is signified by the <code>st_nlink</code> field being zero (which is
		1221	otherwise always forced to be at least one) and all the other fields of
		1222	the stat buffer having unspecified contents.</p>
		1223	<p>Since there is no standard to do this, the portable implementation simply
		1224	calls <code>stat (2)</code> regulalry on the path to see if it changed somehow. You
		1225	can specify a recommended polling interval for this case. If you specify
		1226	a polling interval of <code>0</code> (highly recommended!) then a <i>suitable,
		1227	unspecified default</i> value will be used (which you can expect to be around
		1228	five seconds, although this might change dynamically). Libev will also
		1229	impose a minimum interval which is currently around <code>0.1</code>, but thats
		1230	usually overkill.</p>
		1231	<p>This watcher type is not meant for massive numbers of stat watchers,
		1232	as even with OS-supported change notifications, this can be
		1233	resource-intensive.</p>
		1234	<p>At the time of this writing, no specific OS backends are implemented, but
		1235	if demand increases, at least a kqueue and inotify backend will be added.</p>
		1236	<dl>
		1237	<dt>ev_stat_init (ev_stat , callback, const char path, ev_tstamp interval)</dt>
		1238	<dt>ev_stat_set (ev_stat , const char path, ev_tstamp interval)</dt>
		1239	<dd>
		1240	<p>Configures the watcher to wait for status changes of the given
		1241	<code>path</code>. The <code>interval</code> is a hint on how quickly a change is expected to
		1242	be detected and should normally be specified as <code>0</code> to let libev choose
		1243	a suitable value. The memory pointed to by <code>path</code> must point to the same
		1244	path for as long as the watcher is active.</p>
		1245	<p>The callback will be receive <code>EV_STAT</code> when a change was detected,
		1246	relative to the attributes at the time the watcher was started (or the
		1247	last change was detected).</p>
		1248	</dd>
		1249	<dt>ev_stat_stat (ev_stat *)</dt>
		1250	<dd>
		1251	<p>Updates the stat buffer immediately with new values. If you change the
		1252	watched path in your callback, you could call this fucntion to avoid
		1253	detecting this change (while introducing a race condition). Can also be
		1254	useful simply to find out the new values.</p>
		1255	</dd>
		1256	<dt>ev_statdata attr [read-only]</dt>
		1257	<dd>
		1258	<p>The most-recently detected attributes of the file. Although the type is of
		1259	<code>ev_statdata</code>, this is usually the (or one of the) <code>struct stat</code> types
		1260	suitable for your system. If the <code>st_nlink</code> member is <code>0</code>, then there
		1261	was some error while <code>stat</code>ing the file.</p>
		1262	</dd>
		1263	<dt>ev_statdata prev [read-only]</dt>
		1264	<dd>
		1265	<p>The previous attributes of the file. The callback gets invoked whenever
		1266	<code>prev</code> != <code>attr</code>.</p>
		1267	</dd>
		1268	<dt>ev_tstamp interval [read-only]</dt>
		1269	<dd>
		1270	<p>The specified interval.</p>
		1271	</dd>
		1272	<dt>const char *path [read-only]</dt>
		1273	<dd>
		1274	<p>The filesystem path that is being watched.</p>
		1275	</dd>
		1276	</dl>
		1277	<p>Example: Watch <code>/etc/passwd</code> for attribute changes.</p>
		1278	<pre> static void
		1279	passwd_cb (struct ev_loop loop, ev_stat w, int revents)
		1280	{
		1281	/* /etc/passwd changed in some way */
		1282	if (w->attr.st_nlink)
		1283	{
		1284	printf ("passwd current size %ld\n", (long)w->attr.st_size);
		1285	printf ("passwd current atime %ld\n", (long)w->attr.st_mtime);
		1286	printf ("passwd current mtime %ld\n", (long)w->attr.st_mtime);
		1287	}
		1288	else
		1289	/* you shalt not abuse printf for puts */
		1290	puts ("wow, /etc/passwd is not there, expect problems. "
		1291	"if this is windows, they already arrived\n");
		1292	}
		1293
		1294	...
		1295	ev_stat passwd;
		1296
		1297	ev_stat_init (&passwd, passwd_cb, "/etc/passwd");
		1298	ev_stat_start (loop, &passwd);
		1299
		1300
		1301
		1302
		1303	</pre>
		1304
		1305	</div>
984	<h2 id="code_ev_idle_code_when_you_ve_got_no"><code>ev_idle</code> - when you've got nothing better to do</h2>	1306	<h2 id="code_ev_idle_code_when_you_ve_got_no"><code>ev_idle</code> - when you've got nothing better to do...</h2>
985	<div id="code_ev_idle_code_when_you_ve_got_no-2">	1307	<div id="code_ev_idle_code_when_you_ve_got_no-2">
986	<p>Idle watchers trigger events when there are no other events are pending	1308	<p>Idle watchers trigger events when there are no other events are pending
987	(prepare, check and other idle watchers do not count). That is, as long	1309	(prepare, check and other idle watchers do not count). That is, as long
988	as your process is busy handling sockets or timeouts (or even signals,	1310	as your process is busy handling sockets or timeouts (or even signals,
989	imagine) it will not be triggered. But when your process is idle all idle	1311	imagine) it will not be triggered. But when your process is idle all idle
…		…
1002	<p>Initialises and configures the idle watcher - it has no parameters of any	1324	<p>Initialises and configures the idle watcher - it has no parameters of any
1003	kind. There is a <code>ev_idle_set</code> macro, but using it is utterly pointless,	1325	kind. There is a <code>ev_idle_set</code> macro, but using it is utterly pointless,
1004	believe me.</p>	1326	believe me.</p>
1005	</dd>	1327	</dd>
1006	</dl>	1328	</dl>
1007	<p>Example: dynamically allocate an <code>ev_idle</code>, start it, and in the	1329	<p>Example: Dynamically allocate an <code>ev_idle</code> watcher, start it, and in the
1008	callback, free it. Alos, use no error checking, as usual.</p>	1330	callback, free it. Also, use no error checking, as usual.</p>
1009	<pre> static void	1331	<pre> static void
1010	idle_cb (struct ev_loop loop, struct ev_idle w, int revents)	1332	idle_cb (struct ev_loop loop, struct ev_idle w, int revents)
1011	{	1333	{
1012	free (w);	1334	free (w);
1013	// now do something you wanted to do when the program has	1335	// now do something you wanted to do when the program has
…		…
1022		1344
1023		1345
1024	</pre>	1346	</pre>
1025		1347
1026	</div>	1348	</div>
1027	<h2 id="code_ev_prepare_code_and_code_ev_che"><code>ev_prepare</code> and <code>ev_check</code> - customise your event loop</h2>	1349	<h2 id="code_ev_prepare_code_and_code_ev_che"><code>ev_prepare</code> and <code>ev_check</code> - customise your event loop!</h2>
1028	<div id="code_ev_prepare_code_and_code_ev_che-2">	1350	<div id="code_ev_prepare_code_and_code_ev_che-2">
1029	<p>Prepare and check watchers are usually (but not always) used in tandem:	1351	<p>Prepare and check watchers are usually (but not always) used in tandem:
1030	prepare watchers get invoked before the process blocks and check watchers	1352	prepare watchers get invoked before the process blocks and check watchers
1031	afterwards.</p>	1353	afterwards.</p>
		1354	<p>You <i>must not</i> call <code>ev_loop</code> or similar functions that enter
		1355	the current event loop from either <code>ev_prepare</code> or <code>ev_check</code>
		1356	watchers. Other loops than the current one are fine, however. The
		1357	rationale behind this is that you do not need to check for recursion in
		1358	those watchers, i.e. the sequence will always be <code>ev_prepare</code>, blocking,
		1359	<code>ev_check</code> so if you have one watcher of each kind they will always be
		1360	called in pairs bracketing the blocking call.</p>
1032	<p>Their main purpose is to integrate other event mechanisms into libev and	1361	<p>Their main purpose is to integrate other event mechanisms into libev and
1033	their use is somewhat advanced. This could be used, for example, to track	1362	their use is somewhat advanced. This could be used, for example, to track
1034	variable changes, implement your own watchers, integrate net-snmp or a	1363	variable changes, implement your own watchers, integrate net-snmp or a
1035	coroutine library and lots more.</p>	1364	coroutine library and lots more. They are also occasionally useful if
		1365	you cache some data and want to flush it before blocking (for example,
		1366	in X programs you might want to do an <code>XFlush ()</code> in an <code>ev_prepare</code>
		1367	watcher).</p>
1036	<p>This is done by examining in each prepare call which file descriptors need	1368	<p>This is done by examining in each prepare call which file descriptors need
1037	to be watched by the other library, registering <code>ev_io</code> watchers for	1369	to be watched by the other library, registering <code>ev_io</code> watchers for
1038	them and starting an <code>ev_timer</code> watcher for any timeouts (many libraries	1370	them and starting an <code>ev_timer</code> watcher for any timeouts (many libraries
1039	provide just this functionality). Then, in the check watcher you check for	1371	provide just this functionality). Then, in the check watcher you check for
1040	any events that occured (by checking the pending status of all watchers	1372	any events that occured (by checking the pending status of all watchers
…		…
1056	<p>Initialises and configures the prepare or check watcher - they have no	1388	<p>Initialises and configures the prepare or check watcher - they have no
1057	parameters of any kind. There are <code>ev_prepare_set</code> and <code>ev_check_set</code>	1389	parameters of any kind. There are <code>ev_prepare_set</code> and <code>ev_check_set</code>
1058	macros, but using them is utterly, utterly and completely pointless.</p>	1390	macros, but using them is utterly, utterly and completely pointless.</p>
1059	</dd>	1391	</dd>
1060	</dl>	1392	</dl>
1061	<p>Example: TODO.</p>	1393	<p>Example: To include a library such as adns, you would add IO watchers
		1394	and a timeout watcher in a prepare handler, as required by libadns, and
		1395	in a check watcher, destroy them and call into libadns. What follows is
		1396	pseudo-code only of course:</p>
		1397	<pre> static ev_io iow [nfd];
		1398	static ev_timer tw;
1062		1399
		1400	static void
		1401	io_cb (ev_loop loop, ev_io w, int revents)
		1402	{
		1403	// set the relevant poll flags
		1404	// could also call adns_processreadable etc. here
		1405	struct pollfd fd = (struct pollfd )w->data;
		1406	if (revents & EV_READ ) fd->revents \|= fd->events & POLLIN;
		1407	if (revents & EV_WRITE) fd->revents \|= fd->events & POLLOUT;
		1408	}
1063		1409
		1410	// create io watchers for each fd and a timer before blocking
		1411	static void
		1412	adns_prepare_cb (ev_loop loop, ev_prepare w, int revents)
		1413	{
		1414	int timeout = 3600000;truct pollfd fds [nfd];
		1415	// actual code will need to loop here and realloc etc.
		1416	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));
1064		1417
		1418	/* the callback is illegal, but won't be called as we stop during check */
		1419	ev_timer_init (&tw, 0, timeout * 1e-3);
		1420	ev_timer_start (loop, &tw);
1065		1421
		1422	// create on ev_io per pollfd
		1423	for (int i = 0; i < nfd; ++i)
		1424	{
		1425	ev_io_init (iow + i, io_cb, fds [i].fd,
		1426	((fds [i].events & POLLIN ? EV_READ : 0)
		1427	\| (fds [i].events & POLLOUT ? EV_WRITE : 0)));
1066		1428
		1429	fds [i].revents = 0;
		1430	iow [i].data = fds + i;
		1431	ev_io_start (loop, iow + i);
		1432	}
		1433	}
		1434
		1435	// stop all watchers after blocking
		1436	static void
		1437	adns_check_cb (ev_loop loop, ev_check w, int revents)
		1438	{
		1439	ev_timer_stop (loop, &tw);
		1440
		1441	for (int i = 0; i < nfd; ++i)
		1442	ev_io_stop (loop, iow + i);
		1443
		1444	adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));
		1445	}
		1446
		1447
		1448
		1449
		1450	</pre>
		1451
1067	</div>	1452	</div>
1068	<h2 id="code_ev_embed_code_when_one_backend_"><code>ev_embed</code> - when one backend isn't enough</h2>	1453	<h2 id="code_ev_embed_code_when_one_backend_"><code>ev_embed</code> - when one backend isn't enough...</h2>
1069	<div id="code_ev_embed_code_when_one_backend_-2">	1454	<div id="code_ev_embed_code_when_one_backend_-2">
1070	<p>This is a rather advanced watcher type that lets you embed one event loop	1455	<p>This is a rather advanced watcher type that lets you embed one event loop
1071	into another.</p>	1456	into another (currently only <code>ev_io</code> events are supported in the embedded
		1457	loop, other types of watchers might be handled in a delayed or incorrect
		1458	fashion and must not be used).</p>
1072	<p>There are primarily two reasons you would want that: work around bugs and	1459	<p>There are primarily two reasons you would want that: work around bugs and
1073	prioritise I/O.</p>	1460	prioritise I/O.</p>
1074	<p>As an example for a bug workaround, the kqueue backend might only support	1461	<p>As an example for a bug workaround, the kqueue backend might only support
1075	sockets on some platform, so it is unusable as generic backend, but you	1462	sockets on some platform, so it is unusable as generic backend, but you
1076	still want to make use of it because you have many sockets and it scales	1463	still want to make use of it because you have many sockets and it scales
…		…
1081	<p>As for prioritising I/O: rarely you have the case where some fds have	1468	<p>As for prioritising I/O: rarely you have the case where some fds have
1082	to be watched and handled very quickly (with low latency), and even	1469	to be watched and handled very quickly (with low latency), and even
1083	priorities and idle watchers might have too much overhead. In this case	1470	priorities and idle watchers might have too much overhead. In this case
1084	you would put all the high priority stuff in one loop and all the rest in	1471	you would put all the high priority stuff in one loop and all the rest in
1085	a second one, and embed the second one in the first.</p>	1472	a second one, and embed the second one in the first.</p>
		1473	<p>As long as the watcher is active, the callback will be invoked every time
		1474	there might be events pending in the embedded loop. The callback must then
		1475	call <code>ev_embed_sweep (mainloop, watcher)</code> to make a single sweep and invoke
		1476	their callbacks (you could also start an idle watcher to give the embedded
		1477	loop strictly lower priority for example). You can also set the callback
		1478	to <code>0</code>, in which case the embed watcher will automatically execute the
		1479	embedded loop sweep.</p>
1086	<p>As long as the watcher is started it will automatically handle events. The	1480	<p>As long as the watcher is started it will automatically handle events. The
1087	callback will be invoked whenever some events have been handled. You can	1481	callback will be invoked whenever some events have been handled. You can
1088	set the callback to <code>0</code> to avoid having to specify one if you are not	1482	set the callback to <code>0</code> to avoid having to specify one if you are not
1089	interested in that.</p>	1483	interested in that.</p>
1090	<p>Also, there have not currently been made special provisions for forking:	1484	<p>Also, there have not currently been made special provisions for forking:
…		…
1117	else	1511	else
1118	loop_lo = loop_hi;	1512	loop_lo = loop_hi;
1119		1513
1120	</pre>	1514	</pre>
1121	<dl>	1515	<dl>
1122	<dt>ev_embed_init (ev_embed , callback, struct ev_loop loop)</dt>	1516	<dt>ev_embed_init (ev_embed , callback, struct ev_loop embedded_loop)</dt>
1123	<dt>ev_embed_set (ev_embed , callback, struct ev_loop loop)</dt>	1517	<dt>ev_embed_set (ev_embed , callback, struct ev_loop embedded_loop)</dt>
		1518	<dd>
		1519	<p>Configures the watcher to embed the given loop, which must be
		1520	embeddable. If the callback is <code>0</code>, then <code>ev_embed_sweep</code> will be
		1521	invoked automatically, otherwise it is the responsibility of the callback
		1522	to invoke it (it will continue to be called until the sweep has been done,
		1523	if you do not want thta, you need to temporarily stop the embed watcher).</p>
1124	<dd>	1524	</dd>
1125	<p>Configures the watcher to embed the given loop, which must be embeddable.</p>	1525	<dt>ev_embed_sweep (loop, ev_embed *)</dt>
		1526	<dd>
		1527	<p>Make a single, non-blocking sweep over the embedded loop. This works
		1528	similarly to <code>ev_loop (embedded_loop, EVLOOP_NONBLOCK)</code>, but in the most
		1529	apropriate way for embedded loops.</p>
		1530	</dd>
		1531	<dt>struct ev_loop *loop [read-only]</dt>
		1532	<dd>
		1533	<p>The embedded event loop.</p>
1126	</dd>	1534	</dd>
1127	</dl>	1535	</dl>
1128		1536
1129		1537
1130		1538
1131		1539
1132		1540
1133	</div>	1541	</div>
1134	<h1 id="OTHER_FUNCTIONS">OTHER FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p>	1542	<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>
		1543	<div id="code_ev_fork_code_the_audacity_to_re-2">
		1544	<p>Fork watchers are called when a <code>fork ()</code> was detected (usually because
		1545	whoever is a good citizen cared to tell libev about it by calling
		1546	<code>ev_default_fork</code> or <code>ev_loop_fork</code>). The invocation is done before the
		1547	event loop blocks next and before <code>ev_check</code> watchers are being called,
		1548	and only in the child after the fork. If whoever good citizen calling
		1549	<code>ev_default_fork</code> cheats and calls it in the wrong process, the fork
		1550	handlers will be invoked, too, of course.</p>
		1551	<dl>
		1552	<dt>ev_fork_init (ev_signal *, callback)</dt>
		1553	<dd>
		1554	<p>Initialises and configures the fork watcher - it has no parameters of any
		1555	kind. There is a <code>ev_fork_set</code> macro, but using it is utterly pointless,
		1556	believe me.</p>
		1557	</dd>
		1558	</dl>
		1559
		1560
		1561
		1562
		1563
		1564	</div>
		1565	<h1 id="OTHER_FUNCTIONS">OTHER FUNCTIONS</h1>
1135	<div id="OTHER_FUNCTIONS_CONTENT">	1566	<div id="OTHER_FUNCTIONS_CONTENT">
1136	<p>There are some other functions of possible interest. Described. Here. Now.</p>	1567	<p>There are some other functions of possible interest. Described. Here. Now.</p>
1137	<dl>	1568	<dl>
1138	<dt>ev_once (loop, int fd, int events, ev_tstamp timeout, callback)</dt>	1569	<dt>ev_once (loop, int fd, int events, ev_tstamp timeout, callback)</dt>
1139	<dd>	1570	<dd>
…		…
1163		1594
1164	ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);	1595	ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);
1165		1596
1166	</pre>	1597	</pre>
1167	</dd>	1598	</dd>
1168	<dt>ev_feed_event (loop, watcher, int events)</dt>	1599	<dt>ev_feed_event (ev_loop , watcher , int revents)</dt>
1169	<dd>	1600	<dd>
1170	<p>Feeds the given event set into the event loop, as if the specified event	1601	<p>Feeds the given event set into the event loop, as if the specified event
1171	had happened for the specified watcher (which must be a pointer to an	1602	had happened for the specified watcher (which must be a pointer to an
1172	initialised but not necessarily started event watcher).</p>	1603	initialised but not necessarily started event watcher).</p>
1173	</dd>	1604	</dd>
1174	<dt>ev_feed_fd_event (loop, int fd, int revents)</dt>	1605	<dt>ev_feed_fd_event (ev_loop *, int fd, int revents)</dt>
1175	<dd>	1606	<dd>
1176	<p>Feed an event on the given fd, as if a file descriptor backend detected	1607	<p>Feed an event on the given fd, as if a file descriptor backend detected
1177	the given events it.</p>	1608	the given events it.</p>
1178	</dd>	1609	</dd>
1179	<dt>ev_feed_signal_event (loop, int signum)</dt>	1610	<dt>ev_feed_signal_event (ev_loop *loop, int signum)</dt>
1180	<dd>	1611	<dd>
1181	<p>Feed an event as if the given signal occured (loop must be the default loop!).</p>	1612	<p>Feed an event as if the given signal occured (<code>loop</code> must be the default
		1613	loop!).</p>
1182	</dd>	1614	</dd>
1183	</dl>	1615	</dl>
1184		1616
1185		1617
1186		1618
1187		1619
1188		1620
1189	</div>	1621	</div>
1190	<h1 id="LIBEVENT_EMULATION">LIBEVENT EMULATION</h1><p><a href="#TOP" class="toplink">Top</a></p>	1622	<h1 id="LIBEVENT_EMULATION">LIBEVENT EMULATION</h1>
1191	<div id="LIBEVENT_EMULATION_CONTENT">	1623	<div id="LIBEVENT_EMULATION_CONTENT">
1192	<p>Libev offers a compatibility emulation layer for libevent. It cannot	1624	<p>Libev offers a compatibility emulation layer for libevent. It cannot
1193	emulate the internals of libevent, so here are some usage hints:</p>	1625	emulate the internals of libevent, so here are some usage hints:</p>
1194	<dl>	1626	<dl>
1195	<dt>* Use it by including <event.h>, as usual.</dt>	1627	<dt>* Use it by including <event.h>, as usual.</dt>
…		…
1205	<dt>* The libev emulation is <i>not</i> ABI compatible to libevent, you need	1637	<dt>* The libev emulation is <i>not</i> ABI compatible to libevent, you need
1206	to use the libev header file and library.</dt>	1638	to use the libev header file and library.</dt>
1207	</dl>	1639	</dl>
1208		1640
1209	</div>	1641	</div>
1210	<h1 id="C_SUPPORT">C++ SUPPORT</h1><p><a href="#TOP" class="toplink">Top</a></p>	1642	<h1 id="C_SUPPORT">C++ SUPPORT</h1>
1211	<div id="C_SUPPORT_CONTENT">	1643	<div id="C_SUPPORT_CONTENT">
1212	<p>TBD.</p>	1644	<p>Libev comes with some simplistic wrapper classes for C++ that mainly allow
		1645	you to use some convinience methods to start/stop watchers and also change
		1646	the callback model to a model using method callbacks on objects.</p>
		1647	<p>To use it,</p>
		1648	<pre> #include <ev++.h>
1213		1649
		1650	</pre>
		1651	<p>(it is not installed by default). This automatically includes <cite>ev.h</cite>
		1652	and puts all of its definitions (many of them macros) into the global
		1653	namespace. All C++ specific things are put into the <code>ev</code> namespace.</p>
		1654	<p>It should support all the same embedding options as <cite>ev.h</cite>, most notably
		1655	<code>EV_MULTIPLICITY</code>.</p>
		1656	<p>Here is a list of things available in the <code>ev</code> namespace:</p>
		1657	<dl>
		1658	<dt><code>ev::READ</code>, <code>ev::WRITE</code> etc.</dt>
		1659	<dd>
		1660	<p>These are just enum values with the same values as the <code>EV_READ</code> etc.
		1661	macros from <cite>ev.h</cite>.</p>
		1662	</dd>
		1663	<dt><code>ev::tstamp</code>, <code>ev::now</code></dt>
		1664	<dd>
		1665	<p>Aliases to the same types/functions as with the <code>ev_</code> prefix.</p>
		1666	</dd>
		1667	<dt><code>ev::io</code>, <code>ev::timer</code>, <code>ev::periodic</code>, <code>ev::idle</code>, <code>ev::sig</code> etc.</dt>
		1668	<dd>
		1669	<p>For each <code>ev_TYPE</code> watcher in <cite>ev.h</cite> there is a corresponding class of
		1670	the same name in the <code>ev</code> namespace, with the exception of <code>ev_signal</code>
		1671	which is called <code>ev::sig</code> to avoid clashes with the <code>signal</code> macro
		1672	defines by many implementations.</p>
		1673	<p>All of those classes have these methods:</p>
		1674	<p>
		1675	<dl>
		1676	<dt>ev::TYPE::TYPE (object , object::method )</dt>
		1677	<dt>ev::TYPE::TYPE (object , object::method , struct ev_loop *)</dt>
		1678	<dt>ev::TYPE::~TYPE</dt>
		1679	<dd>
		1680	<p>The constructor takes a pointer to an object and a method pointer to
		1681	the event handler callback to call in this class. The constructor calls
		1682	<code>ev_init</code> for you, which means you have to call the <code>set</code> method
		1683	before starting it. If you do not specify a loop then the constructor
		1684	automatically associates the default loop with this watcher.</p>
		1685	<p>The destructor automatically stops the watcher if it is active.</p>
		1686	</dd>
		1687	<dt>w->set (struct ev_loop *)</dt>
		1688	<dd>
		1689	<p>Associates a different <code>struct ev_loop</code> with this watcher. You can only
		1690	do this when the watcher is inactive (and not pending either).</p>
		1691	</dd>
		1692	<dt>w->set ([args])</dt>
		1693	<dd>
		1694	<p>Basically the same as <code>ev_TYPE_set</code>, with the same args. Must be
		1695	called at least once. Unlike the C counterpart, an active watcher gets
		1696	automatically stopped and restarted.</p>
		1697	</dd>
		1698	<dt>w->start ()</dt>
		1699	<dd>
		1700	<p>Starts the watcher. Note that there is no <code>loop</code> argument as the
		1701	constructor already takes the loop.</p>
		1702	</dd>
		1703	<dt>w->stop ()</dt>
		1704	<dd>
		1705	<p>Stops the watcher if it is active. Again, no <code>loop</code> argument.</p>
		1706	</dd>
		1707	<dt>w->again () <code>ev::timer</code>, <code>ev::periodic</code> only</dt>
		1708	<dd>
		1709	<p>For <code>ev::timer</code> and <code>ev::periodic</code>, this invokes the corresponding
		1710	<code>ev_TYPE_again</code> function.</p>
		1711	</dd>
		1712	<dt>w->sweep () <code>ev::embed</code> only</dt>
		1713	<dd>
		1714	<p>Invokes <code>ev_embed_sweep</code>.</p>
		1715	</dd>
		1716	<dt>w->update () <code>ev::stat</code> only</dt>
		1717	<dd>
		1718	<p>Invokes <code>ev_stat_stat</code>.</p>
		1719	</dd>
		1720	</dl>
		1721	</p>
		1722	</dd>
		1723	</dl>
		1724	<p>Example: Define a class with an IO and idle watcher, start one of them in
		1725	the constructor.</p>
		1726	<pre> class myclass
		1727	{
		1728	ev_io io; void io_cb (ev::io &w, int revents);
		1729	ev_idle idle void idle_cb (ev::idle &w, int revents);
		1730
		1731	myclass ();
		1732	}
		1733
		1734	myclass::myclass (int fd)
		1735	: io (this, &myclass::io_cb),
		1736	idle (this, &myclass::idle_cb)
		1737	{
		1738	io.start (fd, ev::READ);
		1739	}
		1740
		1741
		1742
		1743
		1744	</pre>
		1745
1214	</div>	1746	</div>
1215	<h1 id="AUTHOR">AUTHOR</h1><p><a href="#TOP" class="toplink">Top</a></p>	1747	<h1 id="MACRO_MAGIC">MACRO MAGIC</h1>
		1748	<div id="MACRO_MAGIC_CONTENT">
		1749	<p>Libev can be compiled with a variety of options, the most fundemantal is
		1750	<code>EV_MULTIPLICITY</code>. This option determines wether (most) functions and
		1751	callbacks have an initial <code>struct ev_loop *</code> argument.</p>
		1752	<p>To make it easier to write programs that cope with either variant, the
		1753	following macros are defined:</p>
		1754	<dl>
		1755	<dt><code>EV_A</code>, <code>EV_A_</code></dt>
		1756	<dd>
		1757	<p>This provides the loop <i>argument</i> for functions, if one is required ("ev
		1758	loop argument"). The <code>EV_A</code> form is used when this is the sole argument,
		1759	<code>EV_A_</code> is used when other arguments are following. Example:</p>
		1760	<pre> ev_unref (EV_A);
		1761	ev_timer_add (EV_A_ watcher);
		1762	ev_loop (EV_A_ 0);
		1763
		1764	</pre>
		1765	<p>It assumes the variable <code>loop</code> of type <code>struct ev_loop *</code> is in scope,
		1766	which is often provided by the following macro.</p>
		1767	</dd>
		1768	<dt><code>EV_P</code>, <code>EV_P_</code></dt>
		1769	<dd>
		1770	<p>This provides the loop <i>parameter</i> for functions, if one is required ("ev
		1771	loop parameter"). The <code>EV_P</code> form is used when this is the sole parameter,
		1772	<code>EV_P_</code> is used when other parameters are following. Example:</p>
		1773	<pre> // this is how ev_unref is being declared
		1774	static void ev_unref (EV_P);
		1775
		1776	// this is how you can declare your typical callback
		1777	static void cb (EV_P_ ev_timer *w, int revents)
		1778
		1779	</pre>
		1780	<p>It declares a parameter <code>loop</code> of type <code>struct ev_loop *</code>, quite
		1781	suitable for use with <code>EV_A</code>.</p>
		1782	</dd>
		1783	<dt><code>EV_DEFAULT</code>, <code>EV_DEFAULT_</code></dt>
		1784	<dd>
		1785	<p>Similar to the other two macros, this gives you the value of the default
		1786	loop, if multiple loops are supported ("ev loop default").</p>
		1787	</dd>
		1788	</dl>
		1789	<p>Example: Declare and initialise a check watcher, working regardless of
		1790	wether multiple loops are supported or not.</p>
		1791	<pre> static void
		1792	check_cb (EV_P_ ev_timer *w, int revents)
		1793	{
		1794	ev_check_stop (EV_A_ w);
		1795	}
		1796
		1797	ev_check check;
		1798	ev_check_init (&check, check_cb);
		1799	ev_check_start (EV_DEFAULT_ &check);
		1800	ev_loop (EV_DEFAULT_ 0);
		1801
		1802
		1803
		1804
		1805	</pre>
		1806
		1807	</div>
		1808	<h1 id="EMBEDDING">EMBEDDING</h1>
		1809	<div id="EMBEDDING_CONTENT">
		1810	<p>Libev can (and often is) directly embedded into host
		1811	applications. Examples of applications that embed it include the Deliantra
		1812	Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe)
		1813	and rxvt-unicode.</p>
		1814	<p>The goal is to enable you to just copy the neecssary files into your
		1815	source directory without having to change even a single line in them, so
		1816	you can easily upgrade by simply copying (or having a checked-out copy of
		1817	libev somewhere in your source tree).</p>
		1818
		1819	</div>
		1820	<h2 id="FILESETS">FILESETS</h2>
		1821	<div id="FILESETS_CONTENT">
		1822	<p>Depending on what features you need you need to include one or more sets of files
		1823	in your app.</p>
		1824
		1825	</div>
		1826	<h3 id="CORE_EVENT_LOOP">CORE EVENT LOOP</h3>
		1827	<div id="CORE_EVENT_LOOP_CONTENT">
		1828	<p>To include only the libev core (all the <code>ev_*</code> functions), with manual
		1829	configuration (no autoconf):</p>
		1830	<pre> #define EV_STANDALONE 1
		1831	#include "ev.c"
		1832
		1833	</pre>
		1834	<p>This will automatically include <cite>ev.h</cite>, too, and should be done in a
		1835	single C source file only to provide the function implementations. To use
		1836	it, do the same for <cite>ev.h</cite> in all files wishing to use this API (best
		1837	done by writing a wrapper around <cite>ev.h</cite> that you can include instead and
		1838	where you can put other configuration options):</p>
		1839	<pre> #define EV_STANDALONE 1
		1840	#include "ev.h"
		1841
		1842	</pre>
		1843	<p>Both header files and implementation files can be compiled with a C++
		1844	compiler (at least, thats a stated goal, and breakage will be treated
		1845	as a bug).</p>
		1846	<p>You need the following files in your source tree, or in a directory
		1847	in your include path (e.g. in libev/ when using -Ilibev):</p>
		1848	<pre> ev.h
		1849	ev.c
		1850	ev_vars.h
		1851	ev_wrap.h
		1852
		1853	ev_win32.c required on win32 platforms only
		1854
		1855	ev_select.c only when select backend is enabled (which is by default)
		1856	ev_poll.c only when poll backend is enabled (disabled by default)
		1857	ev_epoll.c only when the epoll backend is enabled (disabled by default)
		1858	ev_kqueue.c only when the kqueue backend is enabled (disabled by default)
		1859	ev_port.c only when the solaris port backend is enabled (disabled by default)
		1860
		1861	</pre>
		1862	<p><cite>ev.c</cite> includes the backend files directly when enabled, so you only need
		1863	to compile this single file.</p>
		1864
		1865	</div>
		1866	<h3 id="LIBEVENT_COMPATIBILITY_API">LIBEVENT COMPATIBILITY API</h3>
		1867	<div id="LIBEVENT_COMPATIBILITY_API_CONTENT">
		1868	<p>To include the libevent compatibility API, also include:</p>
		1869	<pre> #include "event.c"
		1870
		1871	</pre>
		1872	<p>in the file including <cite>ev.c</cite>, and:</p>
		1873	<pre> #include "event.h"
		1874
		1875	</pre>
		1876	<p>in the files that want to use the libevent API. This also includes <cite>ev.h</cite>.</p>
		1877	<p>You need the following additional files for this:</p>
		1878	<pre> event.h
		1879	event.c
		1880
		1881	</pre>
		1882
		1883	</div>
		1884	<h3 id="AUTOCONF_SUPPORT">AUTOCONF SUPPORT</h3>
		1885	<div id="AUTOCONF_SUPPORT_CONTENT">
		1886	<p>Instead of using <code>EV_STANDALONE=1</code> and providing your config in
		1887	whatever way you want, you can also <code>m4_include([libev.m4])</code> in your
		1888	<cite>configure.ac</cite> and leave <code>EV_STANDALONE</code> undefined. <cite>ev.c</cite> will then
		1889	include <cite>config.h</cite> and configure itself accordingly.</p>
		1890	<p>For this of course you need the m4 file:</p>
		1891	<pre> libev.m4
		1892
		1893	</pre>
		1894
		1895	</div>
		1896	<h2 id="PREPROCESSOR_SYMBOLS_MACROS">PREPROCESSOR SYMBOLS/MACROS</h2>
		1897	<div id="PREPROCESSOR_SYMBOLS_MACROS_CONTENT">
		1898	<p>Libev can be configured via a variety of preprocessor symbols you have to define
		1899	before including any of its files. The default is not to build for multiplicity
		1900	and only include the select backend.</p>
		1901	<dl>
		1902	<dt>EV_STANDALONE</dt>
		1903	<dd>
		1904	<p>Must always be <code>1</code> if you do not use autoconf configuration, which
		1905	keeps libev from including <cite>config.h</cite>, and it also defines dummy
		1906	implementations for some libevent functions (such as logging, which is not
		1907	supported). It will also not define any of the structs usually found in
		1908	<cite>event.h</cite> that are not directly supported by the libev core alone.</p>
		1909	</dd>
		1910	<dt>EV_USE_MONOTONIC</dt>
		1911	<dd>
		1912	<p>If defined to be <code>1</code>, libev will try to detect the availability of the
		1913	monotonic clock option at both compiletime and runtime. Otherwise no use
		1914	of the monotonic clock option will be attempted. If you enable this, you
		1915	usually have to link against librt or something similar. Enabling it when
		1916	the functionality isn't available is safe, though, althoguh you have
		1917	to make sure you link against any libraries where the <code>clock_gettime</code>
		1918	function is hiding in (often <cite>-lrt</cite>).</p>
		1919	</dd>
		1920	<dt>EV_USE_REALTIME</dt>
		1921	<dd>
		1922	<p>If defined to be <code>1</code>, libev will try to detect the availability of the
		1923	realtime clock option at compiletime (and assume its availability at
		1924	runtime if successful). Otherwise no use of the realtime clock option will
		1925	be attempted. This effectively replaces <code>gettimeofday</code> by <code>clock_get
		1926	(CLOCK_REALTIME, ...)</code> and will not normally affect correctness. See tzhe note about libraries
		1927	in the description of <code>EV_USE_MONOTONIC</code>, though.</p>
		1928	</dd>
		1929	<dt>EV_USE_SELECT</dt>
		1930	<dd>
		1931	<p>If undefined or defined to be <code>1</code>, libev will compile in support for the
		1932	<code>select</code>(2) backend. No attempt at autodetection will be done: if no
		1933	other method takes over, select will be it. Otherwise the select backend
		1934	will not be compiled in.</p>
		1935	</dd>
		1936	<dt>EV_SELECT_USE_FD_SET</dt>
		1937	<dd>
		1938	<p>If defined to <code>1</code>, then the select backend will use the system <code>fd_set</code>
		1939	structure. This is useful if libev doesn't compile due to a missing
		1940	<code>NFDBITS</code> or <code>fd_mask</code> definition or it misguesses the bitset layout on
		1941	exotic systems. This usually limits the range of file descriptors to some
		1942	low limit such as 1024 or might have other limitations (winsocket only
		1943	allows 64 sockets). The <code>FD_SETSIZE</code> macro, set before compilation, might
		1944	influence the size of the <code>fd_set</code> used.</p>
		1945	</dd>
		1946	<dt>EV_SELECT_IS_WINSOCKET</dt>
		1947	<dd>
		1948	<p>When defined to <code>1</code>, the select backend will assume that
		1949	select/socket/connect etc. don't understand file descriptors but
		1950	wants osf handles on win32 (this is the case when the select to
		1951	be used is the winsock select). This means that it will call
		1952	<code>_get_osfhandle</code> on the fd to convert it to an OS handle. Otherwise,
		1953	it is assumed that all these functions actually work on fds, even
		1954	on win32. Should not be defined on non-win32 platforms.</p>
		1955	</dd>
		1956	<dt>EV_USE_POLL</dt>
		1957	<dd>
		1958	<p>If defined to be <code>1</code>, libev will compile in support for the <code>poll</code>(2)
		1959	backend. Otherwise it will be enabled on non-win32 platforms. It
		1960	takes precedence over select.</p>
		1961	</dd>
		1962	<dt>EV_USE_EPOLL</dt>
		1963	<dd>
		1964	<p>If defined to be <code>1</code>, libev will compile in support for the Linux
		1965	<code>epoll</code>(7) backend. Its availability will be detected at runtime,
		1966	otherwise another method will be used as fallback. This is the
		1967	preferred backend for GNU/Linux systems.</p>
		1968	</dd>
		1969	<dt>EV_USE_KQUEUE</dt>
		1970	<dd>
		1971	<p>If defined to be <code>1</code>, libev will compile in support for the BSD style
		1972	<code>kqueue</code>(2) backend. Its actual availability will be detected at runtime,
		1973	otherwise another method will be used as fallback. This is the preferred
		1974	backend for BSD and BSD-like systems, although on most BSDs kqueue only
		1975	supports some types of fds correctly (the only platform we found that
		1976	supports ptys for example was NetBSD), so kqueue might be compiled in, but
		1977	not be used unless explicitly requested. The best way to use it is to find
		1978	out whether kqueue supports your type of fd properly and use an embedded
		1979	kqueue loop.</p>
		1980	</dd>
		1981	<dt>EV_USE_PORT</dt>
		1982	<dd>
		1983	<p>If defined to be <code>1</code>, libev will compile in support for the Solaris
		1984	10 port style backend. Its availability will be detected at runtime,
		1985	otherwise another method will be used as fallback. This is the preferred
		1986	backend for Solaris 10 systems.</p>
		1987	</dd>
		1988	<dt>EV_USE_DEVPOLL</dt>
		1989	<dd>
		1990	<p>reserved for future expansion, works like the USE symbols above.</p>
		1991	</dd>
		1992	<dt>EV_H</dt>
		1993	<dd>
		1994	<p>The name of the <cite>ev.h</cite> header file used to include it. The default if
		1995	undefined is <code><ev.h></code> in <cite>event.h</cite> and <code>"ev.h"</code> in <cite>ev.c</cite>. This
		1996	can be used to virtually rename the <cite>ev.h</cite> header file in case of conflicts.</p>
		1997	</dd>
		1998	<dt>EV_CONFIG_H</dt>
		1999	<dd>
		2000	<p>If <code>EV_STANDALONE</code> isn't <code>1</code>, this variable can be used to override
		2001	<cite>ev.c</cite>'s idea of where to find the <cite>config.h</cite> file, similarly to
		2002	<code>EV_H</code>, above.</p>
		2003	</dd>
		2004	<dt>EV_EVENT_H</dt>
		2005	<dd>
		2006	<p>Similarly to <code>EV_H</code>, this macro can be used to override <cite>event.c</cite>'s idea
		2007	of how the <cite>event.h</cite> header can be found.</p>
		2008	</dd>
		2009	<dt>EV_PROTOTYPES</dt>
		2010	<dd>
		2011	<p>If defined to be <code>0</code>, then <cite>ev.h</cite> will not define any function
		2012	prototypes, but still define all the structs and other symbols. This is
		2013	occasionally useful if you want to provide your own wrapper functions
		2014	around libev functions.</p>
		2015	</dd>
		2016	<dt>EV_MULTIPLICITY</dt>
		2017	<dd>
		2018	<p>If undefined or defined to <code>1</code>, then all event-loop-specific functions
		2019	will have the <code>struct ev_loop *</code> as first argument, and you can create
		2020	additional independent event loops. Otherwise there will be no support
		2021	for multiple event loops and there is no first event loop pointer
		2022	argument. Instead, all functions act on the single default loop.</p>
		2023	</dd>
		2024	<dt>EV_PERIODIC_ENABLE</dt>
		2025	<dd>
		2026	<p>If undefined or defined to be <code>1</code>, then periodic timers are supported. If
		2027	defined to be <code>0</code>, then they are not. Disabling them saves a few kB of
		2028	code.</p>
		2029	</dd>
		2030	<dt>EV_EMBED_ENABLE</dt>
		2031	<dd>
		2032	<p>If undefined or defined to be <code>1</code>, then embed watchers are supported. If
		2033	defined to be <code>0</code>, then they are not.</p>
		2034	</dd>
		2035	<dt>EV_STAT_ENABLE</dt>
		2036	<dd>
		2037	<p>If undefined or defined to be <code>1</code>, then stat watchers are supported. If
		2038	defined to be <code>0</code>, then they are not.</p>
		2039	</dd>
		2040	<dt>EV_FORK_ENABLE</dt>
		2041	<dd>
		2042	<p>If undefined or defined to be <code>1</code>, then fork watchers are supported. If
		2043	defined to be <code>0</code>, then they are not.</p>
		2044	</dd>
		2045	<dt>EV_MINIMAL</dt>
		2046	<dd>
		2047	<p>If you need to shave off some kilobytes of code at the expense of some
		2048	speed, define this symbol to <code>1</code>. Currently only used for gcc to override
		2049	some inlining decisions, saves roughly 30% codesize of amd64.</p>
		2050	</dd>
		2051	<dt>EV_PID_HASHSIZE</dt>
		2052	<dd>
		2053	<p><code>ev_child</code> watchers use a small hash table to distribute workload by
		2054	pid. The default size is <code>16</code> (or <code>1</code> with <code>EV_MINIMAL</code>), usually more
		2055	than enough. If you need to manage thousands of children you might want to
		2056	increase this value.</p>
		2057	</dd>
		2058	<dt>EV_COMMON</dt>
		2059	<dd>
		2060	<p>By default, all watchers have a <code>void *data</code> member. By redefining
		2061	this macro to a something else you can include more and other types of
		2062	members. You have to define it each time you include one of the files,
		2063	though, and it must be identical each time.</p>
		2064	<p>For example, the perl EV module uses something like this:</p>
		2065	<pre> #define EV_COMMON \
		2066	SV self; / contains this struct */ \
		2067	SV cb_sv, fh /* note no trailing ";" */
		2068
		2069	</pre>
		2070	</dd>
		2071	<dt>EV_CB_DECLARE (type)</dt>
		2072	<dt>EV_CB_INVOKE (watcher, revents)</dt>
		2073	<dt>ev_set_cb (ev, cb)</dt>
		2074	<dd>
		2075	<p>Can be used to change the callback member declaration in each watcher,
		2076	and the way callbacks are invoked and set. Must expand to a struct member
		2077	definition and a statement, respectively. See the <cite>ev.v</cite> header file for
		2078	their default definitions. One possible use for overriding these is to
		2079	avoid the <code>struct ev_loop *</code> as first argument in all cases, or to use
		2080	method calls instead of plain function calls in C++.</p>
		2081
		2082	</div>
		2083	<h2 id="EXAMPLES">EXAMPLES</h2>
		2084	<div id="EXAMPLES_CONTENT">
		2085	<p>For a real-world example of a program the includes libev
		2086	verbatim, you can have a look at the EV perl module
		2087	(<a href="http://software.schmorp.de/pkg/EV.html">http://software.schmorp.de/pkg/EV.html</a>). It has the libev files in
		2088	the <cite>libev/</cite> subdirectory and includes them in the <cite>EV/EVAPI.h</cite> (public
		2089	interface) and <cite>EV.xs</cite> (implementation) files. Only the <cite>EV.xs</cite> file
		2090	will be compiled. It is pretty complex because it provides its own header
		2091	file.</p>
		2092	<p>The usage in rxvt-unicode is simpler. It has a <cite>ev_cpp.h</cite> header file
		2093	that everybody includes and which overrides some autoconf choices:</p>
		2094	<pre> #define EV_USE_POLL 0
		2095	#define EV_MULTIPLICITY 0
		2096	#define EV_PERIODICS 0
		2097	#define EV_CONFIG_H <config.h>
		2098
		2099	#include "ev++.h"
		2100
		2101	</pre>
		2102	<p>And a <cite>ev_cpp.C</cite> implementation file that contains libev proper and is compiled:</p>
		2103	<pre> #include "ev_cpp.h"
		2104	#include "ev.c"
		2105
		2106
		2107
		2108
		2109	</pre>
		2110
		2111	</div>
		2112	<h1 id="COMPLEXITIES">COMPLEXITIES</h1>
		2113	<div id="COMPLEXITIES_CONTENT">
		2114	<p>In this section the complexities of (many of) the algorithms used inside
		2115	libev will be explained. For complexity discussions about backends see the
		2116	documentation for <code>ev_default_init</code>.</p>
		2117	<p>
		2118	<dl>
		2119	<dt>Starting and stopping timer/periodic watchers: O(log skipped_other_timers)</dt>
		2120	<dt>Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)</dt>
		2121	<dt>Starting io/check/prepare/idle/signal/child watchers: O(1)</dt>
		2122	<dt>Stopping check/prepare/idle watchers: O(1)</dt>
		2123	<dt>Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % 16))</dt>
		2124	<dt>Finding the next timer per loop iteration: O(1)</dt>
		2125	<dt>Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)</dt>
		2126	<dt>Activating one watcher: O(1)</dt>
		2127	</dl>
		2128	</p>
		2129
		2130
		2131
		2132
		2133
		2134	</div>
		2135	<h1 id="AUTHOR">AUTHOR</h1>
1216	<div id="AUTHOR_CONTENT">	2136	<div id="AUTHOR_CONTENT">
1217	<p>Marc Lehmann <libev@schmorp.de>.</p>	2137	<p>Marc Lehmann <libev@schmorp.de>.</p>
1218		2138
1219	</div>	2139	</div>
1220	</div></body>	2140	</div></body>
1221	</html>	2141	</html>

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