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Revision 1.54 by root, Tue Nov 27 20:26:51 2007 UTC

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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 10:48:32 2007" />	9	<meta name="created" content="Tue Nov 27 21:26:46 2007" />
10	<meta name="generator" content="Pod::Xhtml 1.57" />	10	<meta name="generator" content="Pod::Xhtml 1.57" />
11	<link rel="stylesheet" href="http://res.tst.eu/pod.css"/></head>	11	<link rel="stylesheet" href="http://res.tst.eu/pod.css"/></head>
12	<body>	12	<body>
13	<div class="pod">	13	<div class="pod">
14	<!-- INDEX START -->	14	<!-- INDEX START -->
15	<h3 id="TOP">Index</h3>	15	<h3 id="TOP">Index</h3>
16		16
17	<ul><li><a href="#NAME">NAME</a></li>	17	<ul><li><a href="#NAME">NAME</a></li>
18	<li><a href="#SYNOPSIS">SYNOPSIS</a></li>	18	<li><a href="#SYNOPSIS">SYNOPSIS</a></li>
		19	<li><a href="#EXAMPLE_PROGRAM">EXAMPLE PROGRAM</a></li>
19	<li><a href="#DESCRIPTION">DESCRIPTION</a></li>	20	<li><a href="#DESCRIPTION">DESCRIPTION</a></li>
20	<li><a href="#FEATURES">FEATURES</a></li>	21	<li><a href="#FEATURES">FEATURES</a></li>
21	<li><a href="#CONVENTIONS">CONVENTIONS</a></li>	22	<li><a href="#CONVENTIONS">CONVENTIONS</a></li>
22	<li><a href="#TIME_REPRESENTATION">TIME REPRESENTATION</a></li>	23	<li><a href="#TIME_REPRESENTATION">TIME REPRESENTATION</a></li>
23	<li><a href="#GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</a></li>	24	<li><a href="#GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</a></li>
24	<li><a href="#FUNCTIONS_CONTROLLING_THE_EVENT_LOOP">FUNCTIONS CONTROLLING THE EVENT LOOP</a></li>	25	<li><a href="#FUNCTIONS_CONTROLLING_THE_EVENT_LOOP">FUNCTIONS CONTROLLING THE EVENT LOOP</a></li>
25	<li><a href="#ANATOMY_OF_A_WATCHER">ANATOMY OF A WATCHER</a>	26	<li><a href="#ANATOMY_OF_A_WATCHER">ANATOMY OF A WATCHER</a>
26	<ul><li><a href="#SUMMARY_OF_GENERIC_WATCHER_FUNCTIONS">SUMMARY OF GENERIC WATCHER FUNCTIONS</a></li>	27	<ul><li><a href="#GENERIC_WATCHER_FUNCTIONS">GENERIC WATCHER FUNCTIONS</a></li>
27	<li><a href="#ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH">ASSOCIATING CUSTOM DATA WITH A WATCHER</a></li>	28	<li><a href="#ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH">ASSOCIATING CUSTOM DATA WITH A WATCHER</a></li>
28	</ul>	29	</ul>
29	</li>	30	</li>
30	<li><a href="#WATCHER_TYPES">WATCHER TYPES</a>	31	<li><a href="#WATCHER_TYPES">WATCHER TYPES</a>
31	<ul><li><a href="#code_ev_io_code_is_this_file_descrip"><code>ev_io</code> - is this file descriptor readable or writable</a></li>	32	<ul><li><a href="#code_ev_io_code_is_this_file_descrip"><code>ev_io</code> - is this file descriptor readable or writable?</a></li>
32	<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>
33	<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>
34	<li><a href="#code_ev_signal_code_signal_me_when_a"><code>ev_signal</code> - signal me when a signal gets signalled</a></li>	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>
35	<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>
36	<li><a href="#code_ev_idle_code_when_you_ve_got_no"><code>ev_idle</code> - when you've got nothing better to do</a></li>	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>
37	<li><a href="#code_ev_prepare_code_and_code_ev_che"><code>ev_prepare</code> and <code>ev_check</code> - customise your event loop</a></li>	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>
38	<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>
39	</ul>	42	</ul>
40	</li>	43	</li>
41	<li><a href="#OTHER_FUNCTIONS">OTHER FUNCTIONS</a></li>	44	<li><a href="#OTHER_FUNCTIONS">OTHER FUNCTIONS</a></li>
42	<li><a href="#LIBEVENT_EMULATION">LIBEVENT EMULATION</a></li>	45	<li><a href="#LIBEVENT_EMULATION">LIBEVENT EMULATION</a></li>
43	<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>
44	<li><a href="#AUTHOR">AUTHOR</a>	60	<li><a href="#AUTHOR">AUTHOR</a>
45	</li>	61	</li>
46	</ul><hr />	62	</ul><hr />
47	<!-- INDEX END -->	63	<!-- INDEX END -->
48		64
…		…
52		68
53	</div>	69	</div>
54	<h1 id="SYNOPSIS">SYNOPSIS</h1><p><a href="#TOP" class="toplink">Top</a></p>	70	<h1 id="SYNOPSIS">SYNOPSIS</h1><p><a href="#TOP" class="toplink">Top</a></p>
55	<div id="SYNOPSIS_CONTENT">	71	<div id="SYNOPSIS_CONTENT">
56	<pre> #include <ev.h>	72	<pre> #include <ev.h>
		73
		74	</pre>
		75
		76	</div>
		77	<h1 id="EXAMPLE_PROGRAM">EXAMPLE PROGRAM</h1><p><a href="#TOP" class="toplink">Top</a></p>
		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	}
57		118
58	</pre>	119	</pre>
59		120
60	</div>	121	</div>
61	<h1 id="DESCRIPTION">DESCRIPTION</h1><p><a href="#TOP" class="toplink">Top</a></p>	122	<h1 id="DESCRIPTION">DESCRIPTION</h1><p><a href="#TOP" class="toplink">Top</a></p>
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72	watcher.</p>	133	watcher.</p>
73		134
74	</div>	135	</div>
75	<h1 id="FEATURES">FEATURES</h1><p><a href="#TOP" class="toplink">Top</a></p>	136	<h1 id="FEATURES">FEATURES</h1><p><a href="#TOP" class="toplink">Top</a></p>
76	<div id="FEATURES_CONTENT">	137	<div id="FEATURES_CONTENT">
77	<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
78	kqueue mechanisms for file descriptor events, relative timers, absolute	139	bsd-specific <code>kqueue</code> and the solaris-specific event port mechanisms
79	timers with customised rescheduling, signal events, process status change	140	for file descriptor events (<code>ev_io</code>), relative timers (<code>ev_timer</code>),
80	events (related to SIGCHLD), and event watchers dealing with the event	141	absolute timers with customised rescheduling (<code>ev_periodic</code>), synchronous
81	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
82	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
83	it to libevent for example).</p>	149	for example).</p>
84		150
85	</div>	151	</div>
86	<h1 id="CONVENTIONS">CONVENTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p>	152	<h1 id="CONVENTIONS">CONVENTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p>
87	<div id="CONVENTIONS_CONTENT">	153	<div id="CONVENTIONS_CONTENT">
88	<p>Libev is very configurable. In this manual the default configuration	154	<p>Libev is very configurable. In this manual the default configuration will
89	will be described, which supports multiple event loops. For more info	155	be described, which supports multiple event loops. For more info about
90	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
91	<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
92	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>
93	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>
94	will not have this argument.</p>
95		160
96	</div>	161	</div>
97	<h1 id="TIME_REPRESENTATION">TIME REPRESENTATION</h1><p><a href="#TOP" class="toplink">Top</a></p>	162	<h1 id="TIME_REPRESENTATION">TIME REPRESENTATION</h1><p><a href="#TOP" class="toplink">Top</a></p>
98	<div id="TIME_REPRESENTATION_CONTENT">	163	<div id="TIME_REPRESENTATION_CONTENT">
99	<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
100	(fractional) number of seconds since the (POSIX) epoch (somewhere near	165	(fractional) number of seconds since the (POSIX) epoch (somewhere near
101	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
102	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
103	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
104	it, you should treat it as such.</p>	169	it, you should treat it as such.</p>
105
106
107
108
109		170
110	</div>	171	</div>
111	<h1 id="GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p>	172	<h1 id="GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p>
112	<div id="GLOBAL_FUNCTIONS_CONTENT">	173	<div id="GLOBAL_FUNCTIONS_CONTENT">
113	<p>These functions can be called anytime, even before initialising the	174	<p>These functions can be called anytime, even before initialising the
…		…
129	version of the library your program was compiled against.</p>	190	version of the library your program was compiled against.</p>
130	<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,
131	as this indicates an incompatible change. Minor versions are usually	192	as this indicates an incompatible change. Minor versions are usually
132	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
133	not a problem.</p>	194	not a problem.</p>
134	<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
135	version:</p>	196	version.</p>
136	<pre> assert (("libev version mismatch",	197	<pre> assert (("libev version mismatch",
137	ev_version_major () == EV_VERSION_MAJOR	198	ev_version_major () == EV_VERSION_MAJOR
138	&& ev_version_minor () >= EV_VERSION_MINOR));	199	&& ev_version_minor () >= EV_VERSION_MINOR));
139		200
140	</pre>	201	</pre>
…		…
168	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
169	<code>ev_embeddable_backends () & ev_supported_backends ()</code>, likewise for	230	<code>ev_embeddable_backends () & ev_supported_backends ()</code>, likewise for
170	recommended ones.</p>	231	recommended ones.</p>
171	<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>
172	</dd>	233	</dd>
173	<dt>ev_set_allocator (void (cb)(void *ptr, long size))</dt>	234	<dt>ev_set_allocator (void (cb)(void *ptr, size_t size))</dt>
174	<dd>	235	<dd>
175	<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
176	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
177	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
178	needs to be allocated, the library might abort or take some potentially	239	allocated, the library might abort or take some potentially destructive
179	destructive action. The default is your system realloc function.</p>	240	action. The default is your system realloc function.</p>
180	<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,
181	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,
182	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>
183	<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
184	retries: better than mine).</p>	245	retries).</p>
185	<pre> static void *	246	<pre> static void *
186	persistent_realloc (void *ptr, long size)	247	persistent_realloc (void *ptr, size_t size)
187	{	248	{
188	for (;;)	249	for (;;)
189	{	250	{
190	void *newptr = realloc (ptr, size);	251	void *newptr = realloc (ptr, size);
191		252
…		…
208	indicating the system call or subsystem causing the problem. If this	269	indicating the system call or subsystem causing the problem. If this
209	callback is set, then libev will expect it to remedy the sitution, no	270	callback is set, then libev will expect it to remedy the sitution, no
210	matter what, when it returns. That is, libev will generally retry the	271	matter what, when it returns. That is, libev will generally retry the
211	requested operation, or, if the condition doesn't go away, do bad stuff	272	requested operation, or, if the condition doesn't go away, do bad stuff
212	(such as abort).</p>	273	(such as abort).</p>
213	<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>
214	<pre> static void	275	<pre> static void
215	fatal_error (const char *msg)	276	fatal_error (const char *msg)
216	{	277	{
217	perror (msg);	278	perror (msg);
218	abort ();	279	abort ();
…		…
354	<dd>	415	<dd>
355	<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
356	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
357	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
358	undefined behaviour (or a failed assertion if assertions are enabled).</p>	419	undefined behaviour (or a failed assertion if assertions are enabled).</p>
359	<p>Example: try to create a event loop that uses epoll and nothing else.</p>	420	<p>Example: Try to create a event loop that uses epoll and nothing else.</p>
360	<pre> struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL \| EVFLAG_NOENV);	421	<pre> struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL \| EVFLAG_NOENV);
361	if (!epoller)	422	if (!epoller)
362	fatal ("no epoll found here, maybe it hides under your chair");	423	fatal ("no epoll found here, maybe it hides under your chair");
363		424
364	</pre>	425	</pre>
…		…
457	be handled here by queueing them when their watcher gets executed.	518	be handled here by queueing them when their watcher gets executed.
458	- 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
459	were used, return, otherwise continue with step *.	520	were used, return, otherwise continue with step *.
460		521
461	</pre>	522	</pre>
462	<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
463	anymore.</p>	524	anymore.</p>
464	<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
465	... 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..)
466	ev_loop (my_loop, 0);	527	ev_loop (my_loop, 0);
467	... jobs done. yeah!	528	... jobs done. yeah!
…		…
486	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
487	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
488	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
489	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
490	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>
491	<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>
492	running when nothing else is active.</p>	553	running when nothing else is active.</p>
493	<pre> struct dv_signal exitsig;	554	<pre> struct ev_signal exitsig;
494	ev_signal_init (&exitsig, sig_cb, SIGINT);	555	ev_signal_init (&exitsig, sig_cb, SIGINT);
495	ev_signal_start (myloop, &exitsig);	556	ev_signal_start (loop, &exitsig);
496	evf_unref (myloop);	557	evf_unref (loop);
497		558
498	</pre>	559	</pre>
499	<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>
500	<pre> ev_ref (myloop);	561	<pre> ev_ref (loop);
501	ev_signal_stop (myloop, &exitsig);	562	ev_signal_stop (loop, &exitsig);
502		563
503	</pre>	564	</pre>
504	</dd>	565	</dd>
505	</dl>	566	</dl>
		567
		568
		569
		570
506		571
507	</div>	572	</div>
508	<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><p><a href="#TOP" class="toplink">Top</a></p>
509	<div id="ANATOMY_OF_A_WATCHER_CONTENT">	574	<div id="ANATOMY_OF_A_WATCHER_CONTENT">
510	<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
…		…
570	</dd>	635	</dd>
571	<dt><code>EV_CHILD</code></dt>	636	<dt><code>EV_CHILD</code></dt>
572	<dd>	637	<dd>
573	<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>
574	</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>
575	<dt><code>EV_IDLE</code></dt>	644	<dt><code>EV_IDLE</code></dt>
576	<dd>	645	<dd>
577	<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>
578	</dd>	647	</dd>
579	<dt><code>EV_PREPARE</code></dt>	648	<dt><code>EV_PREPARE</code></dt>
…		…
584	<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
585	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
586	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
587	(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
588	<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>
589	</dd>	667	</dd>
590	<dt><code>EV_ERROR</code></dt>	668	<dt><code>EV_ERROR</code></dt>
591	<dd>	669	<dd>
592	<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
593	happen because the watcher could not be properly started because libev	671	happen because the watcher could not be properly started because libev
…		…
601	programs, though, so beware.</p>	679	programs, though, so beware.</p>
602	</dd>	680	</dd>
603	</dl>	681	</dl>
604		682
605	</div>	683	</div>
606	<h2 id="SUMMARY_OF_GENERIC_WATCHER_FUNCTIONS">SUMMARY OF GENERIC WATCHER FUNCTIONS</h2>	684	<h2 id="GENERIC_WATCHER_FUNCTIONS">GENERIC WATCHER FUNCTIONS</h2>
607	<div id="SUMMARY_OF_GENERIC_WATCHER_FUNCTIONS-2">	685	<div id="GENERIC_WATCHER_FUNCTIONS_CONTENT">
608	<p>In the following description, <code>TYPE</code> stands for the watcher type,	686	<p>In the following description, <code>TYPE</code> stands for the watcher type,
609	e.g. <code>timer</code> for <code>ev_timer</code> watchers and <code>io</code> for <code>ev_io</code> watchers.</p>	687	e.g. <code>timer</code> for <code>ev_timer</code> watchers and <code>io</code> for <code>ev_io</code> watchers.</p>
610	<dl>	688	<dl>
611	<dt><code>ev_init</code> (ev_TYPE *watcher, callback)</dt>	689	<dt><code>ev_init</code> (ev_TYPE *watcher, callback)</dt>
612	<dd>	690	<dd>
…		…
616	the type-specific <code>ev_TYPE_set</code> macro afterwards to initialise the	694	the type-specific <code>ev_TYPE_set</code> macro afterwards to initialise the
617	type-specific parts. For each type there is also a <code>ev_TYPE_init</code> macro	695	type-specific parts. For each type there is also a <code>ev_TYPE_init</code> macro
618	which rolls both calls into one.</p>	696	which rolls both calls into one.</p>
619	<p>You can reinitialise a watcher at any time as long as it has been stopped	697	<p>You can reinitialise a watcher at any time as long as it has been stopped
620	(or never started) and there are no pending events outstanding.</p>	698	(or never started) and there are no pending events outstanding.</p>
621	<p>The callbakc is always of type <code>void ()(ev_loop loop, ev_TYPE *watcher,	699	<p>The callback is always of type <code>void ()(ev_loop loop, ev_TYPE *watcher,
622	int revents)</code>.</p>	700	int revents)</code>.</p>
623	</dd>	701	</dd>
624	<dt><code>ev_TYPE_set</code> (ev_TYPE *, [args])</dt>	702	<dt><code>ev_TYPE_set</code> (ev_TYPE *, [args])</dt>
625	<dd>	703	<dd>
626	<p>This macro initialises the type-specific parts of a watcher. You need to	704	<p>This macro initialises the type-specific parts of a watcher. You need to
…		…
716		794
717	</div>	795	</div>
718	<h1 id="WATCHER_TYPES">WATCHER TYPES</h1><p><a href="#TOP" class="toplink">Top</a></p>	796	<h1 id="WATCHER_TYPES">WATCHER TYPES</h1><p><a href="#TOP" class="toplink">Top</a></p>
719	<div id="WATCHER_TYPES_CONTENT">	797	<div id="WATCHER_TYPES_CONTENT">
720	<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
721	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>
722		809
723		810
724		811
725		812
726		813
727	</div>	814	</div>
728	<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>
729	<div id="code_ev_io_code_is_this_file_descrip-2">	816	<div id="code_ev_io_code_is_this_file_descrip-2">
730	<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
731	in each iteration of the event loop (This behaviour is called	818	in each iteration of the event loop, or, more precisely, when reading
732	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
733	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
734	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>
735	<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
736	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
737	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
738	required if you know what you are doing).</p>	827	required if you know what you are doing).</p>
739	<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
740	(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
741	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
742	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
743	the same underlying "file open").</p>	832	the same underlying "file open").</p>
744	<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
745	(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
746	<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>
747	<dl>	849	<dl>
748	<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>
749	<dt>ev_io_set (ev_io *, int fd, int events)</dt>	851	<dt>ev_io_set (ev_io *, int fd, int events)</dt>
750	<dd>	852	<dd>
751	<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
752	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
753	EV_WRITE</code> to receive the given events.</p>	855	<code>EV_READ \| EV_WRITE</code> to receive the given events.</p>
754	<p>Please note that most of the more scalable backend mechanisms (for example	856	</dd>
755	epoll and solaris ports) can result in spurious readyness notifications	857	<dt>int fd [read-only]</dt>
756	for file descriptors, so you practically need to use non-blocking I/O (and	858	<dd>
757	treat callback invocation as hint only), or retest separately with a safe	859	<p>The file descriptor being watched.</p>
758	interface before doing I/O (XLib can do this), or force the use of either	860	</dd>
759	<code>EVBACKEND_SELECT</code> or <code>EVBACKEND_POLL</code>, which don't suffer from this	861	<dt>int events [read-only]</dt>
760	problem. Also note that it is quite easy to have your callback invoked	862	<dd>
761	when the readyness condition is no longer valid even when employing	863	<p>The events being watched.</p>
762	typical ways of handling events, so its a good idea to use non-blocking
763	I/O unconditionally.</p>
764	</dd>	864	</dd>
765	</dl>	865	</dl>
766	<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
767	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
768	attempt to read a whole line in the callback:</p>	868	attempt to read a whole line in the callback.</p>
769	<pre> static void	869	<pre> static void
770	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)
771	{	871	{
772	ev_io_stop (loop, w);	872	ev_io_stop (loop, w);
773	.. 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
…		…
784		884
785		885
786	</pre>	886	</pre>
787		887
788	</div>	888	</div>
789	<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>
790	<div id="code_ev_timer_code_relative_and_opti-2">	890	<div id="code_ev_timer_code_relative_and_opti-2">
791	<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
792	given time, and optionally repeating in regular intervals after that.</p>	892	given time, and optionally repeating in regular intervals after that.</p>
793	<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
794	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
…		…
826	repeating. The exact semantics are:</p>	926	repeating. The exact semantics are:</p>
827	<p>If the timer is started but nonrepeating, stop it.</p>	927	<p>If the timer is started but nonrepeating, stop it.</p>
828	<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
829	value), or reset the running timer to the repeat value.</p>	929	value), or reset the running timer to the repeat value.</p>
830	<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
831	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
832	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,
833	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
834	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
835	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
836	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
837	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>
838	</dd>	959	</dd>
839	</dl>	960	</dl>
840	<p>Example: create a timer that fires after 60 seconds.</p>	961	<p>Example: Create a timer that fires after 60 seconds.</p>
841	<pre> static void	962	<pre> static void
842	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)
843	{	964	{
844	.. one minute over, w is actually stopped right here	965	.. one minute over, w is actually stopped right here
845	}	966	}
…		…
847	struct ev_timer mytimer;	968	struct ev_timer mytimer;
848	ev_timer_init (&mytimer, one_minute_cb, 60., 0.);	969	ev_timer_init (&mytimer, one_minute_cb, 60., 0.);
849	ev_timer_start (loop, &mytimer);	970	ev_timer_start (loop, &mytimer);
850		971
851	</pre>	972	</pre>
852	<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
853	inactivity.</p>	974	inactivity.</p>
854	<pre> static void	975	<pre> static void
855	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)
856	{	977	{
857	.. ten seconds without any activity	978	.. ten seconds without any activity
…		…
870		991
871		992
872	</pre>	993	</pre>
873		994
874	</div>	995	</div>
875	<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>
876	<div id="code_ev_periodic_code_to_cron_or_not-2">	997	<div id="code_ev_periodic_code_to_cron_or_not-2">
877	<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
878	(and unfortunately a bit complex).</p>	999	(and unfortunately a bit complex).</p>
879	<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)
880	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
…		…
960	<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
961	when you changed some parameters or the reschedule callback would return	1082	when you changed some parameters or the reschedule callback would return
962	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
963	program when the crontabs have changed).</p>	1084	program when the crontabs have changed).</p>
964	</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>
965	</dl>	1098	</dl>
966	<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
967	system clock is divisible by 3600. The callback invocation times have	1100	system clock is divisible by 3600. The callback invocation times have
968	potentially a lot of jittering, but good long-term stability.</p>	1101	potentially a lot of jittering, but good long-term stability.</p>
969	<pre> static void	1102	<pre> static void
970	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)
971	{	1104	{
…		…
975	struct ev_periodic hourly_tick;	1108	struct ev_periodic hourly_tick;
976	ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);	1109	ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);
977	ev_periodic_start (loop, &hourly_tick);	1110	ev_periodic_start (loop, &hourly_tick);
978		1111
979	</pre>	1112	</pre>
980	<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>
981	<pre> #include <math.h>	1114	<pre> #include <math.h>
982		1115
983	static ev_tstamp	1116	static ev_tstamp
984	my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)	1117	my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)
985	{	1118	{
…		…
987	}	1120	}
988		1121
989	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);
990		1123
991	</pre>	1124	</pre>
992	<p>Example: call a callback every hour, starting now:</p>	1125	<p>Example: Call a callback every hour, starting now:</p>
993	<pre> struct ev_periodic hourly_tick;	1126	<pre> struct ev_periodic hourly_tick;
994	ev_periodic_init (&hourly_tick, clock_cb,	1127	ev_periodic_init (&hourly_tick, clock_cb,
995	fmod (ev_now (loop), 3600.), 3600., 0);	1128	fmod (ev_now (loop), 3600.), 3600., 0);
996	ev_periodic_start (loop, &hourly_tick);	1129	ev_periodic_start (loop, &hourly_tick);
997		1130
…		…
999		1132
1000		1133
1001	</pre>	1134	</pre>
1002		1135
1003	</div>	1136	</div>
1004	<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>
1005	<div id="code_ev_signal_code_signal_me_when_a-2">	1138	<div id="code_ev_signal_code_signal_me_when_a-2">
1006	<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
1007	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
1008	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
1009	normal event processing, like any other event.</p>	1142	normal event processing, like any other event.</p>
…		…
1018	<dt>ev_signal_set (ev_signal *, int signum)</dt>	1151	<dt>ev_signal_set (ev_signal *, int signum)</dt>
1019	<dd>	1152	<dd>
1020	<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
1021	of the <code>SIGxxx</code> constants).</p>	1154	of the <code>SIGxxx</code> constants).</p>
1022	</dd>	1155	</dd>
		1156	<dt>int signum [read-only]</dt>
		1157	<dd>
		1158	<p>The signal the watcher watches out for.</p>
		1159	</dd>
1023	</dl>	1160	</dl>
1024		1161
1025		1162
1026		1163
1027		1164
1028		1165
1029	</div>	1166	</div>
1030	<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>
1031	<div id="code_ev_child_code_wait_for_pid_stat-2">	1168	<div id="code_ev_child_code_watch_out_for_pro-2">
1032	<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
1033	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>
1034	<dl>	1171	<dl>
1035	<dt>ev_child_init (ev_child *, callback, int pid)</dt>	1172	<dt>ev_child_init (ev_child *, callback, int pid)</dt>
1036	<dt>ev_child_set (ev_child *, int pid)</dt>	1173	<dt>ev_child_set (ev_child *, int pid)</dt>
…		…
1040	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
1041	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
1042	<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
1043	process causing the status change.</p>	1180	process causing the status change.</p>
1044	</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>
1045	</dl>	1195	</dl>
1046	<p>Example: try to exit cleanly on SIGINT and SIGTERM.</p>	1196	<p>Example: Try to exit cleanly on SIGINT and SIGTERM.</p>
1047	<pre> static void	1197	<pre> static void
1048	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)
1049	{	1199	{
1050	ev_unloop (loop, EVUNLOOP_ALL);	1200	ev_unloop (loop, EVUNLOOP_ALL);
1051	}	1201	}
…		…
1058		1208
1059		1209
1060	</pre>	1210	</pre>
1061		1211
1062	</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>
1063	<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>
1064	<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">
1065	<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
1066	(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
1067	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,
1068	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
…		…
1081	<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
1082	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,
1083	believe me.</p>	1326	believe me.</p>
1084	</dd>	1327	</dd>
1085	</dl>	1328	</dl>
1086	<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
1087	callback, free it. Alos, use no error checking, as usual.</p>	1330	callback, free it. Also, use no error checking, as usual.</p>
1088	<pre> static void	1331	<pre> static void
1089	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)
1090	{	1333	{
1091	free (w);	1334	free (w);
1092	// now do something you wanted to do when the program has	1335	// now do something you wanted to do when the program has
…		…
1101		1344
1102		1345
1103	</pre>	1346	</pre>
1104		1347
1105	</div>	1348	</div>
1106	<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>
1107	<div id="code_ev_prepare_code_and_code_ev_che-2">	1350	<div id="code_ev_prepare_code_and_code_ev_che-2">
1108	<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:
1109	prepare watchers get invoked before the process blocks and check watchers	1352	prepare watchers get invoked before the process blocks and check watchers
1110	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>
1111	<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
1112	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
1113	variable changes, implement your own watchers, integrate net-snmp or a	1363	variable changes, implement your own watchers, integrate net-snmp or a
1114	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>
1115	<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
1116	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
1117	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
1118	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
1119	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
…		…
1135	<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
1136	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>
1137	macros, but using them is utterly, utterly and completely pointless.</p>	1390	macros, but using them is utterly, utterly and completely pointless.</p>
1138	</dd>	1391	</dd>
1139	</dl>	1392	</dl>
1140	<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;
1141		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	}
1142		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 ()));
1143		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);
1144		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)));
1145		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
1146	</div>	1452	</div>
1147	<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>
1148	<div id="code_ev_embed_code_when_one_backend_-2">	1454	<div id="code_ev_embed_code_when_one_backend_-2">
1149	<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
1150	into another (currently only <code>ev_io</code> events are supported in the embedded	1456	into another (currently only <code>ev_io</code> events are supported in the embedded
1151	loop, other types of watchers might be handled in a delayed or incorrect	1457	loop, other types of watchers might be handled in a delayed or incorrect
1152	fashion and must not be used).</p>	1458	fashion and must not be used).</p>
…		…
1219	<dt>ev_embed_sweep (loop, ev_embed *)</dt>	1525	<dt>ev_embed_sweep (loop, ev_embed *)</dt>
1220	<dd>	1526	<dd>
1221	<p>Make a single, non-blocking sweep over the embedded loop. This works	1527	<p>Make a single, non-blocking sweep over the embedded loop. This works
1222	similarly to <code>ev_loop (embedded_loop, EVLOOP_NONBLOCK)</code>, but in the most	1528	similarly to <code>ev_loop (embedded_loop, EVLOOP_NONBLOCK)</code>, but in the most
1223	apropriate way for embedded loops.</p>	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>
		1534	</dd>
		1535	</dl>
		1536
		1537
		1538
		1539
		1540
		1541	</div>
		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>
1224	</dd>	1557	</dd>
1225	</dl>	1558	</dl>
1226		1559
1227		1560
1228		1561
…		…
1378	</dd>	1711	</dd>
1379	<dt>w->sweep () <code>ev::embed</code> only</dt>	1712	<dt>w->sweep () <code>ev::embed</code> only</dt>
1380	<dd>	1713	<dd>
1381	<p>Invokes <code>ev_embed_sweep</code>.</p>	1714	<p>Invokes <code>ev_embed_sweep</code>.</p>
1382	</dd>	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>
1383	</dl>	1720	</dl>
1384	</p>	1721	</p>
1385	</dd>	1722	</dd>
1386	</dl>	1723	</dl>
1387	<p>Example: Define a class with an IO and idle watcher, start one of them in	1724	<p>Example: Define a class with an IO and idle watcher, start one of them in
…		…
1399	idle (this, &myclass::idle_cb)	1736	idle (this, &myclass::idle_cb)
1400	{	1737	{
1401	io.start (fd, ev::READ);	1738	io.start (fd, ev::READ);
1402	}	1739	}
1403		1740
		1741
		1742
		1743
1404	</pre>	1744	</pre>
		1745
		1746	</div>
		1747	<h1 id="MACRO_MAGIC">MACRO MAGIC</h1><p><a href="#TOP" class="toplink">Top</a></p>
		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><p><a href="#TOP" class="toplink">Top</a></p>
		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><p><a href="#TOP" class="toplink">Top</a></p>
		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
1405		2133
1406	</div>	2134	</div>
1407	<h1 id="AUTHOR">AUTHOR</h1><p><a href="#TOP" class="toplink">Top</a></p>	2135	<h1 id="AUTHOR">AUTHOR</h1><p><a href="#TOP" class="toplink">Top</a></p>
1408	<div id="AUTHOR_CONTENT">	2136	<div id="AUTHOR_CONTENT">
1409	<p>Marc Lehmann <libev@schmorp.de>.</p>	2137	<p>Marc Lehmann <libev@schmorp.de>.</p>
1410		2138
1411	</div>	2139	</div>
1412	</div></body>	2140	</div></body>
1413	</html>	2141	</html>

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Revision 1.54 by root, Tue Nov 27 20:26:51 2007 UTC