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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>" />
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12	<body>	12	<body>
13	<div class="pod">	13	<div class="pod">
14	<!-- INDEX START -->	14	<!-- INDEX START -->
…		…
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="#DESCRIPTION">DESCRIPTION</a></li>	19	<li><a href="#DESCRIPTION">DESCRIPTION</a></li>
20	<li><a href="#FEATURES">FEATURES</a></li>	20	<li><a href="#FEATURES">FEATURES</a></li>
21	<li><a href="#CONVENTIONS">CONVENTIONS</a></li>	21	<li><a href="#CONVENTIONS">CONVENTIONS</a></li>
		22	<li><a href="#TIME_REPRESENTATION">TIME REPRESENTATION</a></li>
22	<li><a href="#TIME_AND_OTHER_GLOBAL_FUNCTIONS">TIME AND OTHER GLOBAL FUNCTIONS</a></li>	23	<li><a href="#GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</a></li>
23	<li><a href="#FUNCTIONS_CONTROLLING_THE_EVENT_LOOP">FUNCTIONS CONTROLLING THE EVENT LOOP</a></li>	24	<li><a href="#FUNCTIONS_CONTROLLING_THE_EVENT_LOOP">FUNCTIONS CONTROLLING THE EVENT LOOP</a></li>
24	<li><a href="#ANATOMY_OF_A_WATCHER">ANATOMY OF A WATCHER</a>	25	<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>
25	<ul><li><a href="#ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH">ASSOCIATING CUSTOM DATA WITH A WATCHER</a></li>	27	<li><a href="#ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH">ASSOCIATING CUSTOM DATA WITH A WATCHER</a></li>
26	</ul>	28	</ul>
27	</li>	29	</li>
28	<li><a href="#WATCHER_TYPES">WATCHER TYPES</a>	30	<li><a href="#WATCHER_TYPES">WATCHER TYPES</a>
29	<ul><li><a href="#struct_ev_io_is_my_file_descriptor_r">struct ev_io - is my file descriptor readable or writable</a></li>	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>
30	<li><a href="#struct_ev_timer_relative_and_optiona">struct ev_timer - relative and optionally recurring timeouts</a></li>	32	<li><a href="#code_ev_timer_code_relative_and_opti"><code>ev_timer</code> - relative and optionally recurring timeouts</a></li>
31	<li><a href="#ev_periodic_to_cron_or_not_to_cron_i">ev_periodic - to cron or not to cron it</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>
32	<li><a href="#ev_signal_signal_me_when_a_signal_ge">ev_signal - signal me when a signal gets signalled</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>
33	<li><a href="#ev_child_wait_for_pid_status_changes">ev_child - wait for pid status changes</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>
34	<li><a href="#ev_idle_when_you_ve_got_nothing_bett">ev_idle - when you've got nothing better to do</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>
35	<li><a href="#prepare_and_check_your_hooks_into_th">prepare and check - your hooks into the event loop</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>
		38	<li><a href="#code_ev_embed_code_when_one_backend_"><code>ev_embed</code> - when one backend isn't enough</a></li>
36	</ul>	39	</ul>
37	</li>	40	</li>
38	<li><a href="#OTHER_FUNCTIONS">OTHER FUNCTIONS</a></li>	41	<li><a href="#OTHER_FUNCTIONS">OTHER FUNCTIONS</a></li>
		42	<li><a href="#LIBEVENT_EMULATION">LIBEVENT EMULATION</a></li>
		43	<li><a href="#C_SUPPORT">C++ SUPPORT</a></li>
		44	<li><a href="#EMBEDDING">EMBEDDING</a>
		45	<ul><li><a href="#FILESETS">FILESETS</a>
		46	<ul><li><a href="#CORE_EVENT_LOOP">CORE EVENT LOOP</a></li>
		47	<li><a href="#LIBEVENT_COMPATIBILITY_API">LIBEVENT COMPATIBILITY API</a></li>
		48	<li><a href="#AUTOCONF_SUPPORT">AUTOCONF SUPPORT</a></li>
		49	</ul>
		50	</li>
		51	<li><a href="#PREPROCESSOR_SYMBOLS_MACROS">PREPROCESSOR SYMBOLS/MACROS</a></li>
		52	<li><a href="#EXAMPLES">EXAMPLES</a></li>
		53	</ul>
		54	</li>
39	<li><a href="#AUTHOR">AUTHOR</a>	55	<li><a href="#AUTHOR">AUTHOR</a>
40	</li>	56	</li>
41	</ul><hr />	57	</ul><hr />
42	<!-- INDEX END -->	58	<!-- INDEX END -->
43		59
…		…
72	<p>Libev supports select, poll, the linux-specific epoll and the bsd-specific	88	<p>Libev supports select, poll, the linux-specific epoll and the bsd-specific
73	kqueue mechanisms for file descriptor events, relative timers, absolute	89	kqueue mechanisms for file descriptor events, relative timers, absolute
74	timers with customised rescheduling, signal events, process status change	90	timers with customised rescheduling, signal events, process status change
75	events (related to SIGCHLD), and event watchers dealing with the event	91	events (related to SIGCHLD), and event watchers dealing with the event
76	loop mechanism itself (idle, prepare and check watchers). It also is quite	92	loop mechanism itself (idle, prepare and check watchers). It also is quite
77	fast (see a <a href="http://libev.schmorp.de/bench.html">benchmark</a> comparing it	93	fast (see this <a href="http://libev.schmorp.de/bench.html">benchmark</a> comparing
78	to libevent).</p>	94	it to libevent for example).</p>
79		95
80	</div>	96	</div>
81	<h1 id="CONVENTIONS">CONVENTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p>	97	<h1 id="CONVENTIONS">CONVENTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p>
82	<div id="CONVENTIONS_CONTENT">	98	<div id="CONVENTIONS_CONTENT">
83	<p>Libev is very configurable. In this manual the default configuration	99	<p>Libev is very configurable. In this manual the default configuration
84	will be described, which supports multiple event loops. For more info	100	will be described, which supports multiple event loops. For more info
85	about various configuraiton options please have a look at the file	101	about various configuration options please have a look at the file
86	<cite>README.embed</cite> in the libev distribution. If libev was configured without	102	<cite>README.embed</cite> in the libev distribution. If libev was configured without
87	support for multiple event loops, then all functions taking an initial	103	support for multiple event loops, then all functions taking an initial
88	argument of name <code>loop</code> (which is always of type <code>struct ev_loop *</code>)	104	argument of name <code>loop</code> (which is always of type <code>struct ev_loop *</code>)
89	will not have this argument.</p>	105	will not have this argument.</p>
90		106
91	</div>	107	</div>
92	<h1 id="TIME_AND_OTHER_GLOBAL_FUNCTIONS">TIME AND OTHER GLOBAL FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p>	108	<h1 id="TIME_REPRESENTATION">TIME REPRESENTATION</h1><p><a href="#TOP" class="toplink">Top</a></p>
93	<div id="TIME_AND_OTHER_GLOBAL_FUNCTIONS_CONT">	109	<div id="TIME_REPRESENTATION_CONTENT">
94	<p>Libev represents time as a single floating point number, representing the	110	<p>Libev represents time as a single floating point number, representing the
95	(fractional) number of seconds since the (POSIX) epoch (somewhere near	111	(fractional) number of seconds since the (POSIX) epoch (somewhere near
96	the beginning of 1970, details are complicated, don't ask). This type is	112	the beginning of 1970, details are complicated, don't ask). This type is
97	called <code>ev_tstamp</code>, which is what you should use too. It usually aliases	113	called <code>ev_tstamp</code>, which is what you should use too. It usually aliases
98	to the double type in C.</p>	114	to the <code>double</code> type in C, and when you need to do any calculations on
		115	it, you should treat it as such.</p>
		116
		117
		118
		119
		120
		121	</div>
		122	<h1 id="GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p>
		123	<div id="GLOBAL_FUNCTIONS_CONTENT">
		124	<p>These functions can be called anytime, even before initialising the
		125	library in any way.</p>
99	<dl>	126	<dl>
100	<dt>ev_tstamp ev_time ()</dt>	127	<dt>ev_tstamp ev_time ()</dt>
101	<dd>	128	<dd>
102	<p>Returns the current time as libev would use it.</p>	129	<p>Returns the current time as libev would use it. Please note that the
		130	<code>ev_now</code> function is usually faster and also often returns the timestamp
		131	you actually want to know.</p>
103	</dd>	132	</dd>
104	<dt>int ev_version_major ()</dt>	133	<dt>int ev_version_major ()</dt>
105	<dt>int ev_version_minor ()</dt>	134	<dt>int ev_version_minor ()</dt>
106	<dd>	135	<dd>
107	<p>You can find out the major and minor version numbers of the library	136	<p>You can find out the major and minor version numbers of the library
108	you linked against by calling the functions <code>ev_version_major</code> and	137	you linked against by calling the functions <code>ev_version_major</code> and
109	<code>ev_version_minor</code>. If you want, you can compare against the global	138	<code>ev_version_minor</code>. If you want, you can compare against the global
110	symbols <code>EV_VERSION_MAJOR</code> and <code>EV_VERSION_MINOR</code>, which specify the	139	symbols <code>EV_VERSION_MAJOR</code> and <code>EV_VERSION_MINOR</code>, which specify the
111	version of the library your program was compiled against.</p>	140	version of the library your program was compiled against.</p>
112	<p>Usually, its a good idea to terminate if the major versions mismatch,	141	<p>Usually, it's a good idea to terminate if the major versions mismatch,
113	as this indicates an incompatible change. Minor versions are usually	142	as this indicates an incompatible change. Minor versions are usually
114	compatible to older versions, so a larger minor version alone is usually	143	compatible to older versions, so a larger minor version alone is usually
115	not a problem.</p>	144	not a problem.</p>
		145	<p>Example: make sure we haven't accidentally been linked against the wrong
		146	version:</p>
		147	<pre> assert (("libev version mismatch",
		148	ev_version_major () == EV_VERSION_MAJOR
		149	&& ev_version_minor () >= EV_VERSION_MINOR));
		150
		151	</pre>
		152	</dd>
		153	<dt>unsigned int ev_supported_backends ()</dt>
		154	<dd>
		155	<p>Return the set of all backends (i.e. their corresponding <code>EV_BACKEND_*</code>
		156	value) compiled into this binary of libev (independent of their
		157	availability on the system you are running on). See <code>ev_default_loop</code> for
		158	a description of the set values.</p>
		159	<p>Example: make sure we have the epoll method, because yeah this is cool and
		160	a must have and can we have a torrent of it please!!!11</p>
		161	<pre> assert (("sorry, no epoll, no sex",
		162	ev_supported_backends () & EVBACKEND_EPOLL));
		163
		164	</pre>
		165	</dd>
		166	<dt>unsigned int ev_recommended_backends ()</dt>
		167	<dd>
		168	<p>Return the set of all backends compiled into this binary of libev and also
		169	recommended for this platform. This set is often smaller than the one
		170	returned by <code>ev_supported_backends</code>, as for example kqueue is broken on
		171	most BSDs and will not be autodetected unless you explicitly request it
		172	(assuming you know what you are doing). This is the set of backends that
		173	libev will probe for if you specify no backends explicitly.</p>
		174	</dd>
		175	<dt>unsigned int ev_embeddable_backends ()</dt>
		176	<dd>
		177	<p>Returns the set of backends that are embeddable in other event loops. This
		178	is the theoretical, all-platform, value. To find which backends
		179	might be supported on the current system, you would need to look at
		180	<code>ev_embeddable_backends () & ev_supported_backends ()</code>, likewise for
		181	recommended ones.</p>
		182	<p>See the description of <code>ev_embed</code> watchers for more info.</p>
116	</dd>	183	</dd>
117	<dt>ev_set_allocator (void (cb)(void *ptr, long size))</dt>	184	<dt>ev_set_allocator (void (cb)(void *ptr, long size))</dt>
118	<dd>	185	<dd>
119	<p>Sets the allocation function to use (the prototype is similar to the	186	<p>Sets the allocation function to use (the prototype is similar to the
120	realloc function). It is used to allocate and free memory (no surprises	187	realloc C function, the semantics are identical). It is used to allocate
121	here). If it returns zero when memory needs to be allocated, the library	188	and free memory (no surprises here). If it returns zero when memory
122	might abort or take some potentially destructive action. The default is	189	needs to be allocated, the library might abort or take some potentially
123	your system realloc function.</p>	190	destructive action. The default is your system realloc function.</p>
124	<p>You could override this function in high-availability programs to, say,	191	<p>You could override this function in high-availability programs to, say,
125	free some memory if it cannot allocate memory, to use a special allocator,	192	free some memory if it cannot allocate memory, to use a special allocator,
126	or even to sleep a while and retry until some memory is available.</p>	193	or even to sleep a while and retry until some memory is available.</p>
		194	<p>Example: replace the libev allocator with one that waits a bit and then
		195	retries: better than mine).</p>
		196	<pre> static void *
		197	persistent_realloc (void *ptr, long size)
		198	{
		199	for (;;)
		200	{
		201	void *newptr = realloc (ptr, size);
		202
		203	if (newptr)
		204	return newptr;
		205
		206	sleep (60);
		207	}
		208	}
		209
		210	...
		211	ev_set_allocator (persistent_realloc);
		212
		213	</pre>
127	</dd>	214	</dd>
128	<dt>ev_set_syserr_cb (void (cb)(const char msg));</dt>	215	<dt>ev_set_syserr_cb (void (cb)(const char msg));</dt>
129	<dd>	216	<dd>
130	<p>Set the callback function to call on a retryable syscall error (such	217	<p>Set the callback function to call on a retryable syscall error (such
131	as failed select, poll, epoll_wait). The message is a printable string	218	as failed select, poll, epoll_wait). The message is a printable string
132	indicating the system call or subsystem causing the problem. If this	219	indicating the system call or subsystem causing the problem. If this
133	callback is set, then libev will expect it to remedy the sitution, no	220	callback is set, then libev will expect it to remedy the sitution, no
134	matter what, when it returns. That is, libev will geenrally retry the	221	matter what, when it returns. That is, libev will generally retry the
135	requested operation, or, if the condition doesn't go away, do bad stuff	222	requested operation, or, if the condition doesn't go away, do bad stuff
136	(such as abort).</p>	223	(such as abort).</p>
		224	<p>Example: do the same thing as libev does internally:</p>
		225	<pre> static void
		226	fatal_error (const char *msg)
		227	{
		228	perror (msg);
		229	abort ();
		230	}
		231
		232	...
		233	ev_set_syserr_cb (fatal_error);
		234
		235	</pre>
137	</dd>	236	</dd>
138	</dl>	237	</dl>
139		238
140	</div>	239	</div>
141	<h1 id="FUNCTIONS_CONTROLLING_THE_EVENT_LOOP">FUNCTIONS CONTROLLING THE EVENT LOOP</h1><p><a href="#TOP" class="toplink">Top</a></p>	240	<h1 id="FUNCTIONS_CONTROLLING_THE_EVENT_LOOP">FUNCTIONS CONTROLLING THE EVENT LOOP</h1><p><a href="#TOP" class="toplink">Top</a></p>
142	<div id="FUNCTIONS_CONTROLLING_THE_EVENT_LOOP-2">	241	<div id="FUNCTIONS_CONTROLLING_THE_EVENT_LOOP-2">
143	<p>An event loop is described by a <code>struct ev_loop *</code>. The library knows two	242	<p>An event loop is described by a <code>struct ev_loop *</code>. The library knows two
144	types of such loops, the <i>default</i> loop, which supports signals and child	243	types of such loops, the <i>default</i> loop, which supports signals and child
145	events, and dynamically created loops which do not.</p>	244	events, and dynamically created loops which do not.</p>
146	<p>If you use threads, a common model is to run the default event loop	245	<p>If you use threads, a common model is to run the default event loop
147	in your main thread (or in a separate thrad) and for each thread you	246	in your main thread (or in a separate thread) and for each thread you
148	create, you also create another event loop. Libev itself does no lockign	247	create, you also create another event loop. Libev itself does no locking
149	whatsoever, so if you mix calls to different event loops, make sure you	248	whatsoever, so if you mix calls to the same event loop in different
150	lock (this is usually a bad idea, though, even if done right).</p>	249	threads, make sure you lock (this is usually a bad idea, though, even if
		250	done correctly, because it's hideous and inefficient).</p>
151	<dl>	251	<dl>
152	<dt>struct ev_loop *ev_default_loop (unsigned int flags)</dt>	252	<dt>struct ev_loop *ev_default_loop (unsigned int flags)</dt>
153	<dd>	253	<dd>
154	<p>This will initialise the default event loop if it hasn't been initialised	254	<p>This will initialise the default event loop if it hasn't been initialised
155	yet and return it. If the default loop could not be initialised, returns	255	yet and return it. If the default loop could not be initialised, returns
156	false. If it already was initialised it simply returns it (and ignores the	256	false. If it already was initialised it simply returns it (and ignores the
157	flags).</p>	257	flags. If that is troubling you, check <code>ev_backend ()</code> afterwards).</p>
158	<p>If you don't know what event loop to use, use the one returned from this	258	<p>If you don't know what event loop to use, use the one returned from this
159	function.</p>	259	function.</p>
160	<p>The flags argument can be used to specify special behaviour or specific	260	<p>The flags argument can be used to specify special behaviour or specific
161	backends to use, and is usually specified as 0 (or EVFLAG_AUTO)</p>	261	backends to use, and is usually specified as <code>0</code> (or <code>EVFLAG_AUTO</code>).</p>
162	<p>It supports the following flags:</p>	262	<p>The following flags are supported:</p>
163	<p>	263	<p>
164	<dl>	264	<dl>
165	<dt>EVFLAG_AUTO</dt>	265	<dt><code>EVFLAG_AUTO</code></dt>
166	<dd>	266	<dd>
167	<p>The default flags value. Use this if you have no clue (its the right	267	<p>The default flags value. Use this if you have no clue (it's the right
168	thing, believe me).</p>	268	thing, believe me).</p>
169	</dd>	269	</dd>
170	<dt>EVFLAG_NOENV</dt>	270	<dt><code>EVFLAG_NOENV</code></dt>
171	<dd>
172	<p>If this flag bit is ored into the flag value then libev will <i>not</i> look
173	at the environment variable <code>LIBEV_FLAGS</code>. Otherwise (the default), this
174	environment variable will override the flags completely. This is useful
175	to try out specific backends to tets their performance, or to work around
176	bugs.</p>
177	</dd>	271	<dd>
178	<dt>EVMETHOD_SELECT portable select backend</dt>	272	<p>If this flag bit is ored into the flag value (or the program runs setuid
179	<dt>EVMETHOD_POLL poll backend (everywhere except windows)</dt>	273	or setgid) then libev will <i>not</i> look at the environment variable
180	<dt>EVMETHOD_EPOLL linux only</dt>	274	<code>LIBEV_FLAGS</code>. Otherwise (the default), this environment variable will
181	<dt>EVMETHOD_KQUEUE some bsds only</dt>	275	override the flags completely if it is found in the environment. This is
182	<dt>EVMETHOD_DEVPOLL solaris 8 only</dt>	276	useful to try out specific backends to test their performance, or to work
183	<dt>EVMETHOD_PORT solaris 10 only</dt>	277	around bugs.</p>
184	<dd>	278	</dd>
185	<p>If one or more of these are ored into the flags value, then only these	279	<dt><code>EVBACKEND_SELECT</code> (value 1, portable select backend)</dt>
186	backends will be tried (in the reverse order as given here). If one are	280	<dd>
187	specified, any backend will do.</p>	281	<p>This is your standard select(2) backend. Not <i>completely</i> standard, as
		282	libev tries to roll its own fd_set with no limits on the number of fds,
		283	but if that fails, expect a fairly low limit on the number of fds when
		284	using this backend. It doesn't scale too well (O(highest_fd)), but its usually
		285	the fastest backend for a low number of fds.</p>
		286	</dd>
		287	<dt><code>EVBACKEND_POLL</code> (value 2, poll backend, available everywhere except on windows)</dt>
		288	<dd>
		289	<p>And this is your standard poll(2) backend. It's more complicated than
		290	select, but handles sparse fds better and has no artificial limit on the
		291	number of fds you can use (except it will slow down considerably with a
		292	lot of inactive fds). It scales similarly to select, i.e. O(total_fds).</p>
		293	</dd>
		294	<dt><code>EVBACKEND_EPOLL</code> (value 4, Linux)</dt>
		295	<dd>
		296	<p>For few fds, this backend is a bit little slower than poll and select,
		297	but it scales phenomenally better. While poll and select usually scale like
		298	O(total_fds) where n is the total number of fds (or the highest fd), epoll scales
		299	either O(1) or O(active_fds).</p>
		300	<p>While stopping and starting an I/O watcher in the same iteration will
		301	result in some caching, there is still a syscall per such incident
		302	(because the fd could point to a different file description now), so its
		303	best to avoid that. Also, dup()ed file descriptors might not work very
		304	well if you register events for both fds.</p>
		305	<p>Please note that epoll sometimes generates spurious notifications, so you
		306	need to use non-blocking I/O or other means to avoid blocking when no data
		307	(or space) is available.</p>
		308	</dd>
		309	<dt><code>EVBACKEND_KQUEUE</code> (value 8, most BSD clones)</dt>
		310	<dd>
		311	<p>Kqueue deserves special mention, as at the time of this writing, it
		312	was broken on all BSDs except NetBSD (usually it doesn't work with
		313	anything but sockets and pipes, except on Darwin, where of course its
		314	completely useless). For this reason its not being "autodetected"
		315	unless you explicitly specify it explicitly in the flags (i.e. using
		316	<code>EVBACKEND_KQUEUE</code>).</p>
		317	<p>It scales in the same way as the epoll backend, but the interface to the
		318	kernel is more efficient (which says nothing about its actual speed, of
		319	course). While starting and stopping an I/O watcher does not cause an
		320	extra syscall as with epoll, it still adds up to four event changes per
		321	incident, so its best to avoid that.</p>
		322	</dd>
		323	<dt><code>EVBACKEND_DEVPOLL</code> (value 16, Solaris 8)</dt>
		324	<dd>
		325	<p>This is not implemented yet (and might never be).</p>
		326	</dd>
		327	<dt><code>EVBACKEND_PORT</code> (value 32, Solaris 10)</dt>
		328	<dd>
		329	<p>This uses the Solaris 10 port mechanism. As with everything on Solaris,
		330	it's really slow, but it still scales very well (O(active_fds)).</p>
		331	<p>Please note that solaris ports can result in a lot of spurious
		332	notifications, so you need to use non-blocking I/O or other means to avoid
		333	blocking when no data (or space) is available.</p>
		334	</dd>
		335	<dt><code>EVBACKEND_ALL</code></dt>
		336	<dd>
		337	<p>Try all backends (even potentially broken ones that wouldn't be tried
		338	with <code>EVFLAG_AUTO</code>). Since this is a mask, you can do stuff such as
		339	<code>EVBACKEND_ALL & ~EVBACKEND_KQUEUE</code>.</p>
188	</dd>	340	</dd>
189	</dl>	341	</dl>
190	</p>	342	</p>
		343	<p>If one or more of these are ored into the flags value, then only these
		344	backends will be tried (in the reverse order as given here). If none are
		345	specified, most compiled-in backend will be tried, usually in reverse
		346	order of their flag values :)</p>
		347	<p>The most typical usage is like this:</p>
		348	<pre> if (!ev_default_loop (0))
		349	fatal ("could not initialise libev, bad $LIBEV_FLAGS in environment?");
		350
		351	</pre>
		352	<p>Restrict libev to the select and poll backends, and do not allow
		353	environment settings to be taken into account:</p>
		354	<pre> ev_default_loop (EVBACKEND_POLL \| EVBACKEND_SELECT \| EVFLAG_NOENV);
		355
		356	</pre>
		357	<p>Use whatever libev has to offer, but make sure that kqueue is used if
		358	available (warning, breaks stuff, best use only with your own private
		359	event loop and only if you know the OS supports your types of fds):</p>
		360	<pre> ev_default_loop (ev_recommended_backends () \| EVBACKEND_KQUEUE);
		361
		362	</pre>
191	</dd>	363	</dd>
192	<dt>struct ev_loop *ev_loop_new (unsigned int flags)</dt>	364	<dt>struct ev_loop *ev_loop_new (unsigned int flags)</dt>
193	<dd>	365	<dd>
194	<p>Similar to <code>ev_default_loop</code>, but always creates a new event loop that is	366	<p>Similar to <code>ev_default_loop</code>, but always creates a new event loop that is
195	always distinct from the default loop. Unlike the default loop, it cannot	367	always distinct from the default loop. Unlike the default loop, it cannot
196	handle signal and child watchers, and attempts to do so will be greeted by	368	handle signal and child watchers, and attempts to do so will be greeted by
197	undefined behaviour (or a failed assertion if assertions are enabled).</p>	369	undefined behaviour (or a failed assertion if assertions are enabled).</p>
		370	<p>Example: try to create a event loop that uses epoll and nothing else.</p>
		371	<pre> struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL \| EVFLAG_NOENV);
		372	if (!epoller)
		373	fatal ("no epoll found here, maybe it hides under your chair");
		374
		375	</pre>
198	</dd>	376	</dd>
199	<dt>ev_default_destroy ()</dt>	377	<dt>ev_default_destroy ()</dt>
200	<dd>	378	<dd>
201	<p>Destroys the default loop again (frees all memory and kernel state	379	<p>Destroys the default loop again (frees all memory and kernel state
202	etc.). This stops all registered event watchers (by not touching them in	380	etc.). None of the active event watchers will be stopped in the normal
203	any way whatsoever, although you cnanot rely on this :).</p>	381	sense, so e.g. <code>ev_is_active</code> might still return true. It is your
		382	responsibility to either stop all watchers cleanly yoursef <i>before</i>
		383	calling this function, or cope with the fact afterwards (which is usually
		384	the easiest thing, youc na just ignore the watchers and/or <code>free ()</code> them
		385	for example).</p>
204	</dd>	386	</dd>
205	<dt>ev_loop_destroy (loop)</dt>	387	<dt>ev_loop_destroy (loop)</dt>
206	<dd>	388	<dd>
207	<p>Like <code>ev_default_destroy</code>, but destroys an event loop created by an	389	<p>Like <code>ev_default_destroy</code>, but destroys an event loop created by an
208	earlier call to <code>ev_loop_new</code>.</p>	390	earlier call to <code>ev_loop_new</code>.</p>
…		…
211	<dd>	393	<dd>
212	<p>This function reinitialises the kernel state for backends that have	394	<p>This function reinitialises the kernel state for backends that have
213	one. Despite the name, you can call it anytime, but it makes most sense	395	one. Despite the name, you can call it anytime, but it makes most sense
214	after forking, in either the parent or child process (or both, but that	396	after forking, in either the parent or child process (or both, but that
215	again makes little sense).</p>	397	again makes little sense).</p>
216	<p>You <i>must</i> call this function after forking if and only if you want to	398	<p>You <i>must</i> call this function in the child process after forking if and
217	use the event library in both processes. If you just fork+exec, you don't	399	only if you want to use the event library in both processes. If you just
218	have to call it.</p>	400	fork+exec, you don't have to call it.</p>
219	<p>The function itself is quite fast and its usually not a problem to call	401	<p>The function itself is quite fast and it's usually not a problem to call
220	it just in case after a fork. To make this easy, the function will fit in	402	it just in case after a fork. To make this easy, the function will fit in
221	quite nicely into a call to <code>pthread_atfork</code>:</p>	403	quite nicely into a call to <code>pthread_atfork</code>:</p>
222	<pre> pthread_atfork (0, 0, ev_default_fork);	404	<pre> pthread_atfork (0, 0, ev_default_fork);
223		405
224	</pre>	406	</pre>
		407	<p>At the moment, <code>EVBACKEND_SELECT</code> and <code>EVBACKEND_POLL</code> are safe to use
		408	without calling this function, so if you force one of those backends you
		409	do not need to care.</p>
225	</dd>	410	</dd>
226	<dt>ev_loop_fork (loop)</dt>	411	<dt>ev_loop_fork (loop)</dt>
227	<dd>	412	<dd>
228	<p>Like <code>ev_default_fork</code>, but acts on an event loop created by	413	<p>Like <code>ev_default_fork</code>, but acts on an event loop created by
229	<code>ev_loop_new</code>. Yes, you have to call this on every allocated event loop	414	<code>ev_loop_new</code>. Yes, you have to call this on every allocated event loop
230	after fork, and how you do this is entirely your own problem.</p>	415	after fork, and how you do this is entirely your own problem.</p>
231	</dd>	416	</dd>
232	<dt>unsigned int ev_method (loop)</dt>	417	<dt>unsigned int ev_backend (loop)</dt>
233	<dd>	418	<dd>
234	<p>Returns one of the <code>EVMETHOD_*</code> flags indicating the event backend in	419	<p>Returns one of the <code>EVBACKEND_*</code> flags indicating the event backend in
235	use.</p>	420	use.</p>
236	</dd>	421	</dd>
237	<dt>ev_tstamp = ev_now (loop)</dt>	422	<dt>ev_tstamp ev_now (loop)</dt>
238	<dd>	423	<dd>
239	<p>Returns the current "event loop time", which is the time the event loop	424	<p>Returns the current "event loop time", which is the time the event loop
240	got events and started processing them. This timestamp does not change	425	received events and started processing them. This timestamp does not
241	as long as callbacks are being processed, and this is also the base time	426	change as long as callbacks are being processed, and this is also the base
242	used for relative timers. You can treat it as the timestamp of the event	427	time used for relative timers. You can treat it as the timestamp of the
243	occuring (or more correctly, the mainloop finding out about it).</p>	428	event occuring (or more correctly, libev finding out about it).</p>
244	</dd>	429	</dd>
245	<dt>ev_loop (loop, int flags)</dt>	430	<dt>ev_loop (loop, int flags)</dt>
246	<dd>	431	<dd>
247	<p>Finally, this is it, the event handler. This function usually is called	432	<p>Finally, this is it, the event handler. This function usually is called
248	after you initialised all your watchers and you want to start handling	433	after you initialised all your watchers and you want to start handling
249	events.</p>	434	events.</p>
250	<p>If the flags argument is specified as 0, it will not return until either	435	<p>If the flags argument is specified as <code>0</code>, it will not return until
251	no event watchers are active anymore or <code>ev_unloop</code> was called.</p>	436	either no event watchers are active anymore or <code>ev_unloop</code> was called.</p>
		437	<p>Please note that an explicit <code>ev_unloop</code> is usually better than
		438	relying on all watchers to be stopped when deciding when a program has
		439	finished (especially in interactive programs), but having a program that
		440	automatically loops as long as it has to and no longer by virtue of
		441	relying on its watchers stopping correctly is a thing of beauty.</p>
252	<p>A flags value of <code>EVLOOP_NONBLOCK</code> will look for new events, will handle	442	<p>A flags value of <code>EVLOOP_NONBLOCK</code> will look for new events, will handle
253	those events and any outstanding ones, but will not block your process in	443	those events and any outstanding ones, but will not block your process in
254	case there are no events.</p>	444	case there are no events and will return after one iteration of the loop.</p>
255	<p>A flags value of <code>EVLOOP_ONESHOT</code> will look for new events (waiting if	445	<p>A flags value of <code>EVLOOP_ONESHOT</code> will look for new events (waiting if
256	neccessary) and will handle those and any outstanding ones. It will block	446	neccessary) and will handle those and any outstanding ones. It will block
257	your process until at least one new event arrives.</p>	447	your process until at least one new event arrives, and will return after
258	<p>This flags value could be used to implement alternative looping	448	one iteration of the loop. This is useful if you are waiting for some
259	constructs, but the <code>prepare</code> and <code>check</code> watchers provide a better and	449	external event in conjunction with something not expressible using other
260	more generic mechanism.</p>	450	libev watchers. However, a pair of <code>ev_prepare</code>/<code>ev_check</code> watchers is
		451	usually a better approach for this kind of thing.</p>
		452	<p>Here are the gory details of what <code>ev_loop</code> does:</p>
		453	<pre> * If there are no active watchers (reference count is zero), return.
		454	- Queue prepare watchers and then call all outstanding watchers.
		455	- If we have been forked, recreate the kernel state.
		456	- Update the kernel state with all outstanding changes.
		457	- Update the "event loop time".
		458	- Calculate for how long to block.
		459	- Block the process, waiting for any events.
		460	- Queue all outstanding I/O (fd) events.
		461	- Update the "event loop time" and do time jump handling.
		462	- Queue all outstanding timers.
		463	- Queue all outstanding periodics.
		464	- If no events are pending now, queue all idle watchers.
		465	- Queue all check watchers.
		466	- Call all queued watchers in reverse order (i.e. check watchers first).
		467	Signals and child watchers are implemented as I/O watchers, and will
		468	be handled here by queueing them when their watcher gets executed.
		469	- If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK
		470	were used, return, otherwise continue with step *.
		471
		472	</pre>
		473	<p>Example: queue some jobs and then loop until no events are outsanding
		474	anymore.</p>
		475	<pre> ... queue jobs here, make sure they register event watchers as long
		476	... as they still have work to do (even an idle watcher will do..)
		477	ev_loop (my_loop, 0);
		478	... jobs done. yeah!
		479
		480	</pre>
261	</dd>	481	</dd>
262	<dt>ev_unloop (loop, how)</dt>	482	<dt>ev_unloop (loop, how)</dt>
263	<dd>	483	<dd>
264	<p>Can be used to make a call to <code>ev_loop</code> return early. The <code>how</code> argument	484	<p>Can be used to make a call to <code>ev_loop</code> return early (but only after it
		485	has processed all outstanding events). The <code>how</code> argument must be either
265	must be either <code>EVUNLOOP_ONCE</code>, which will make the innermost <code>ev_loop</code>	486	<code>EVUNLOOP_ONE</code>, which will make the innermost <code>ev_loop</code> call return, or
266	call return, or <code>EVUNLOOP_ALL</code>, which will make all nested <code>ev_loop</code>	487	<code>EVUNLOOP_ALL</code>, which will make all nested <code>ev_loop</code> calls return.</p>
267	calls return.</p>
268	</dd>	488	</dd>
269	<dt>ev_ref (loop)</dt>	489	<dt>ev_ref (loop)</dt>
270	<dt>ev_unref (loop)</dt>	490	<dt>ev_unref (loop)</dt>
271	<dd>	491	<dd>
272	<p>Ref/unref can be used to add or remove a refcount on the event loop: Every	492	<p>Ref/unref can be used to add or remove a reference count on the event
273	watcher keeps one reference. If you have a long-runing watcher you never	493	loop: Every watcher keeps one reference, and as long as the reference
274	unregister that should not keep ev_loop from running, ev_unref() after	494	count is nonzero, <code>ev_loop</code> will not return on its own. If you have
275	starting, and ev_ref() before stopping it. Libev itself uses this for	495	a watcher you never unregister that should not keep <code>ev_loop</code> from
276	example for its internal signal pipe: It is not visible to you as a user	496	returning, ev_unref() after starting, and ev_ref() before stopping it. For
277	and should not keep <code>ev_loop</code> from exiting if the work is done. It is	497	example, libev itself uses this for its internal signal pipe: It is not
278	also an excellent way to do this for generic recurring timers or from	498	visible to the libev user and should not keep <code>ev_loop</code> from exiting if
279	within third-party libraries. Just remember to unref after start and ref	499	no event watchers registered by it are active. It is also an excellent
280	before stop.</p>	500	way to do this for generic recurring timers or from within third-party
		501	libraries. Just remember to <i>unref after start</i> and <i>ref before stop</i>.</p>
		502	<p>Example: create a signal watcher, but keep it from keeping <code>ev_loop</code>
		503	running when nothing else is active.</p>
		504	<pre> struct dv_signal exitsig;
		505	ev_signal_init (&exitsig, sig_cb, SIGINT);
		506	ev_signal_start (myloop, &exitsig);
		507	evf_unref (myloop);
		508
		509	</pre>
		510	<p>Example: for some weird reason, unregister the above signal handler again.</p>
		511	<pre> ev_ref (myloop);
		512	ev_signal_stop (myloop, &exitsig);
		513
		514	</pre>
281	</dd>	515	</dd>
282	</dl>	516	</dl>
283		517
284	</div>	518	</div>
285	<h1 id="ANATOMY_OF_A_WATCHER">ANATOMY OF A WATCHER</h1><p><a href="#TOP" class="toplink">Top</a></p>	519	<h1 id="ANATOMY_OF_A_WATCHER">ANATOMY OF A WATCHER</h1><p><a href="#TOP" class="toplink">Top</a></p>
286	<div id="ANATOMY_OF_A_WATCHER_CONTENT">	520	<div id="ANATOMY_OF_A_WATCHER_CONTENT">
287	<p>A watcher is a structure that you create and register to record your	521	<p>A watcher is a structure that you create and register to record your
288	interest in some event. For instance, if you want to wait for STDIN to	522	interest in some event. For instance, if you want to wait for STDIN to
289	become readable, you would create an ev_io watcher for that:</p>	523	become readable, you would create an <code>ev_io</code> watcher for that:</p>
290	<pre> static void my_cb (struct ev_loop loop, struct ev_io w, int revents)	524	<pre> static void my_cb (struct ev_loop loop, struct ev_io w, int revents)
291	{	525	{
292	ev_io_stop (w);	526	ev_io_stop (w);
293	ev_unloop (loop, EVUNLOOP_ALL);	527	ev_unloop (loop, EVUNLOOP_ALL);
294	}	528	}
…		…
317	with a watcher-specific start function (<code>ev_<type>_start (loop, watcher	551	with a watcher-specific start function (<code>ev_<type>_start (loop, watcher
318	*)</code>), and you can stop watching for events at any time by calling the	552	*)</code>), and you can stop watching for events at any time by calling the
319	corresponding stop function (<code>ev_<type>_stop (loop, watcher *)</code>.</p>	553	corresponding stop function (<code>ev_<type>_stop (loop, watcher *)</code>.</p>
320	<p>As long as your watcher is active (has been started but not stopped) you	554	<p>As long as your watcher is active (has been started but not stopped) you
321	must not touch the values stored in it. Most specifically you must never	555	must not touch the values stored in it. Most specifically you must never
322	reinitialise it or call its set method.</p>	556	reinitialise it or call its <code>set</code> macro.</p>
323	<p>You cna check whether an event is active by calling the <code>ev_is_active
324	(watcher *)</code> macro. To see whether an event is outstanding (but the
325	callback for it has not been called yet) you cna use the <code>ev_is_pending
326	(watcher *)</code> macro.</p>
327	<p>Each and every callback receives the event loop pointer as first, the	557	<p>Each and every callback receives the event loop pointer as first, the
328	registered watcher structure as second, and a bitset of received events as	558	registered watcher structure as second, and a bitset of received events as
329	third argument.</p>	559	third argument.</p>
330	<p>The rceeived events usually include a single bit per event type received	560	<p>The received events usually include a single bit per event type received
331	(you can receive multiple events at the same time). The possible bit masks	561	(you can receive multiple events at the same time). The possible bit masks
332	are:</p>	562	are:</p>
333	<dl>	563	<dl>
334	<dt>EV_READ</dt>	564	<dt><code>EV_READ</code></dt>
335	<dt>EV_WRITE</dt>	565	<dt><code>EV_WRITE</code></dt>
336	<dd>	566	<dd>
337	<p>The file descriptor in the ev_io watcher has become readable and/or	567	<p>The file descriptor in the <code>ev_io</code> watcher has become readable and/or
338	writable.</p>	568	writable.</p>
339	</dd>	569	</dd>
340	<dt>EV_TIMEOUT</dt>	570	<dt><code>EV_TIMEOUT</code></dt>
341	<dd>
342	<p>The ev_timer watcher has timed out.</p>
343	</dd>	571	<dd>
344	<dt>EV_PERIODIC</dt>	572	<p>The <code>ev_timer</code> watcher has timed out.</p>
345	<dd>	573	</dd>
346	<p>The ev_periodic watcher has timed out.</p>	574	<dt><code>EV_PERIODIC</code></dt>
347	</dd>	575	<dd>
348	<dt>EV_SIGNAL</dt>	576	<p>The <code>ev_periodic</code> watcher has timed out.</p>
349	<dd>	577	</dd>
		578	<dt><code>EV_SIGNAL</code></dt>
		579	<dd>
350	<p>The signal specified in the ev_signal watcher has been received by a thread.</p>	580	<p>The signal specified in the <code>ev_signal</code> watcher has been received by a thread.</p>
351	</dd>
352	<dt>EV_CHILD</dt>
353	<dd>	581	</dd>
		582	<dt><code>EV_CHILD</code></dt>
		583	<dd>
354	<p>The pid specified in the ev_child watcher has received a status change.</p>	584	<p>The pid specified in the <code>ev_child</code> watcher has received a status change.</p>
355	</dd>
356	<dt>EV_IDLE</dt>
357	<dd>	585	</dd>
		586	<dt><code>EV_IDLE</code></dt>
		587	<dd>
358	<p>The ev_idle watcher has determined that you have nothing better to do.</p>	588	<p>The <code>ev_idle</code> watcher has determined that you have nothing better to do.</p>
359	</dd>
360	<dt>EV_PREPARE</dt>
361	<dt>EV_CHECK</dt>
362	<dd>	589	</dd>
		590	<dt><code>EV_PREPARE</code></dt>
		591	<dt><code>EV_CHECK</code></dt>
		592	<dd>
363	<p>All ev_prepare watchers are invoked just <i>before</i> <code>ev_loop</code> starts	593	<p>All <code>ev_prepare</code> watchers are invoked just <i>before</i> <code>ev_loop</code> starts
364	to gather new events, and all ev_check watchers are invoked just after	594	to gather new events, and all <code>ev_check</code> watchers are invoked just after
365	<code>ev_loop</code> has gathered them, but before it invokes any callbacks for any	595	<code>ev_loop</code> has gathered them, but before it invokes any callbacks for any
366	received events. Callbacks of both watcher types can start and stop as	596	received events. Callbacks of both watcher types can start and stop as
367	many watchers as they want, and all of them will be taken into account	597	many watchers as they want, and all of them will be taken into account
368	(for example, a ev_prepare watcher might start an idle watcher to keep	598	(for example, a <code>ev_prepare</code> watcher might start an idle watcher to keep
369	<code>ev_loop</code> from blocking).</p>	599	<code>ev_loop</code> from blocking).</p>
370	</dd>	600	</dd>
371	<dt>EV_ERROR</dt>	601	<dt><code>EV_ERROR</code></dt>
372	<dd>	602	<dd>
373	<p>An unspecified error has occured, the watcher has been stopped. This might	603	<p>An unspecified error has occured, the watcher has been stopped. This might
374	happen because the watcher could not be properly started because libev	604	happen because the watcher could not be properly started because libev
375	ran out of memory, a file descriptor was found to be closed or any other	605	ran out of memory, a file descriptor was found to be closed or any other
376	problem. You best act on it by reporting the problem and somehow coping	606	problem. You best act on it by reporting the problem and somehow coping
…		…
382	programs, though, so beware.</p>	612	programs, though, so beware.</p>
383	</dd>	613	</dd>
384	</dl>	614	</dl>
385		615
386	</div>	616	</div>
		617	<h2 id="SUMMARY_OF_GENERIC_WATCHER_FUNCTIONS">SUMMARY OF GENERIC WATCHER FUNCTIONS</h2>
		618	<div id="SUMMARY_OF_GENERIC_WATCHER_FUNCTIONS-2">
		619	<p>In the following description, <code>TYPE</code> stands for the watcher type,
		620	e.g. <code>timer</code> for <code>ev_timer</code> watchers and <code>io</code> for <code>ev_io</code> watchers.</p>
		621	<dl>
		622	<dt><code>ev_init</code> (ev_TYPE *watcher, callback)</dt>
		623	<dd>
		624	<p>This macro initialises the generic portion of a watcher. The contents
		625	of the watcher object can be arbitrary (so <code>malloc</code> will do). Only
		626	the generic parts of the watcher are initialised, you <i>need</i> to call
		627	the type-specific <code>ev_TYPE_set</code> macro afterwards to initialise the
		628	type-specific parts. For each type there is also a <code>ev_TYPE_init</code> macro
		629	which rolls both calls into one.</p>
		630	<p>You can reinitialise a watcher at any time as long as it has been stopped
		631	(or never started) and there are no pending events outstanding.</p>
		632	<p>The callbakc is always of type <code>void ()(ev_loop loop, ev_TYPE *watcher,
		633	int revents)</code>.</p>
		634	</dd>
		635	<dt><code>ev_TYPE_set</code> (ev_TYPE *, [args])</dt>
		636	<dd>
		637	<p>This macro initialises the type-specific parts of a watcher. You need to
		638	call <code>ev_init</code> at least once before you call this macro, but you can
		639	call <code>ev_TYPE_set</code> any number of times. You must not, however, call this
		640	macro on a watcher that is active (it can be pending, however, which is a
		641	difference to the <code>ev_init</code> macro).</p>
		642	<p>Although some watcher types do not have type-specific arguments
		643	(e.g. <code>ev_prepare</code>) you still need to call its <code>set</code> macro.</p>
		644	</dd>
		645	<dt><code>ev_TYPE_init</code> (ev_TYPE *watcher, callback, [args])</dt>
		646	<dd>
		647	<p>This convinience macro rolls both <code>ev_init</code> and <code>ev_TYPE_set</code> macro
		648	calls into a single call. This is the most convinient method to initialise
		649	a watcher. The same limitations apply, of course.</p>
		650	</dd>
		651	<dt><code>ev_TYPE_start</code> (loop , ev_TYPE watcher)</dt>
		652	<dd>
		653	<p>Starts (activates) the given watcher. Only active watchers will receive
		654	events. If the watcher is already active nothing will happen.</p>
		655	</dd>
		656	<dt><code>ev_TYPE_stop</code> (loop , ev_TYPE watcher)</dt>
		657	<dd>
		658	<p>Stops the given watcher again (if active) and clears the pending
		659	status. It is possible that stopped watchers are pending (for example,
		660	non-repeating timers are being stopped when they become pending), but
		661	<code>ev_TYPE_stop</code> ensures that the watcher is neither active nor pending. If
		662	you want to free or reuse the memory used by the watcher it is therefore a
		663	good idea to always call its <code>ev_TYPE_stop</code> function.</p>
		664	</dd>
		665	<dt>bool ev_is_active (ev_TYPE *watcher)</dt>
		666	<dd>
		667	<p>Returns a true value iff the watcher is active (i.e. it has been started
		668	and not yet been stopped). As long as a watcher is active you must not modify
		669	it.</p>
		670	</dd>
		671	<dt>bool ev_is_pending (ev_TYPE *watcher)</dt>
		672	<dd>
		673	<p>Returns a true value iff the watcher is pending, (i.e. it has outstanding
		674	events but its callback has not yet been invoked). As long as a watcher
		675	is pending (but not active) you must not call an init function on it (but
		676	<code>ev_TYPE_set</code> is safe) and you must make sure the watcher is available to
		677	libev (e.g. you cnanot <code>free ()</code> it).</p>
		678	</dd>
		679	<dt>callback = ev_cb (ev_TYPE *watcher)</dt>
		680	<dd>
		681	<p>Returns the callback currently set on the watcher.</p>
		682	</dd>
		683	<dt>ev_cb_set (ev_TYPE *watcher, callback)</dt>
		684	<dd>
		685	<p>Change the callback. You can change the callback at virtually any time
		686	(modulo threads).</p>
		687	</dd>
		688	</dl>
		689
		690
		691
		692
		693
		694	</div>
387	<h2 id="ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH">ASSOCIATING CUSTOM DATA WITH A WATCHER</h2>	695	<h2 id="ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH">ASSOCIATING CUSTOM DATA WITH A WATCHER</h2>
388	<div id="ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH-2">	696	<div id="ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH-2">
389	<p>Each watcher has, by default, a member <code>void *data</code> that you can change	697	<p>Each watcher has, by default, a member <code>void *data</code> that you can change
390	and read at any time, libev will completely ignore it. This cna be used	698	and read at any time, libev will completely ignore it. This can be used
391	to associate arbitrary data with your watcher. If you need more data and	699	to associate arbitrary data with your watcher. If you need more data and
392	don't want to allocate memory and store a pointer to it in that data	700	don't want to allocate memory and store a pointer to it in that data
393	member, you can also "subclass" the watcher type and provide your own	701	member, you can also "subclass" the watcher type and provide your own
394	data:</p>	702	data:</p>
395	<pre> struct my_io	703	<pre> struct my_io
…		…
421	<h1 id="WATCHER_TYPES">WATCHER TYPES</h1><p><a href="#TOP" class="toplink">Top</a></p>	729	<h1 id="WATCHER_TYPES">WATCHER TYPES</h1><p><a href="#TOP" class="toplink">Top</a></p>
422	<div id="WATCHER_TYPES_CONTENT">	730	<div id="WATCHER_TYPES_CONTENT">
423	<p>This section describes each watcher in detail, but will not repeat	731	<p>This section describes each watcher in detail, but will not repeat
424	information given in the last section.</p>	732	information given in the last section.</p>
425		733
		734
		735
		736
		737
426	</div>	738	</div>
427	<h2 id="struct_ev_io_is_my_file_descriptor_r">struct ev_io - is my file descriptor readable or writable</h2>	739	<h2 id="code_ev_io_code_is_this_file_descrip"><code>ev_io</code> - is this file descriptor readable or writable</h2>
428	<div id="struct_ev_io_is_my_file_descriptor_r-2">	740	<div id="code_ev_io_code_is_this_file_descrip-2">
429	<p>I/O watchers check whether a file descriptor is readable or writable	741	<p>I/O watchers check whether a file descriptor is readable or writable
430	in each iteration of the event loop (This behaviour is called	742	in each iteration of the event loop (This behaviour is called
431	level-triggering because you keep receiving events as long as the	743	level-triggering because you keep receiving events as long as the
432	condition persists. Remember you cna stop the watcher if you don't want to	744	condition persists. Remember you can stop the watcher if you don't want to
433	act on the event and neither want to receive future events).</p>	745	act on the event and neither want to receive future events).</p>
		746	<p>In general you can register as many read and/or write event watchers per
		747	fd as you want (as long as you don't confuse yourself). Setting all file
		748	descriptors to non-blocking mode is also usually a good idea (but not
		749	required if you know what you are doing).</p>
		750	<p>You have to be careful with dup'ed file descriptors, though. Some backends
		751	(the linux epoll backend is a notable example) cannot handle dup'ed file
		752	descriptors correctly if you register interest in two or more fds pointing
		753	to the same underlying file/socket etc. description (that is, they share
		754	the same underlying "file open").</p>
		755	<p>If you must do this, then force the use of a known-to-be-good backend
		756	(at the time of this writing, this includes only <code>EVBACKEND_SELECT</code> and
		757	<code>EVBACKEND_POLL</code>).</p>
434	<dl>	758	<dl>
435	<dt>ev_io_init (ev_io *, callback, int fd, int events)</dt>	759	<dt>ev_io_init (ev_io *, callback, int fd, int events)</dt>
436	<dt>ev_io_set (ev_io *, int fd, int events)</dt>	760	<dt>ev_io_set (ev_io *, int fd, int events)</dt>
437	<dd>	761	<dd>
438	<p>Configures an ev_io watcher. The fd is the file descriptor to rceeive	762	<p>Configures an <code>ev_io</code> watcher. The fd is the file descriptor to rceeive
439	events for and events is either <code>EV_READ</code>, <code>EV_WRITE</code> or <code>EV_READ \|	763	events for and events is either <code>EV_READ</code>, <code>EV_WRITE</code> or <code>EV_READ \|
440	EV_WRITE</code> to receive the given events.</p>	764	EV_WRITE</code> to receive the given events.</p>
		765	<p>Please note that most of the more scalable backend mechanisms (for example
		766	epoll and solaris ports) can result in spurious readyness notifications
		767	for file descriptors, so you practically need to use non-blocking I/O (and
		768	treat callback invocation as hint only), or retest separately with a safe
		769	interface before doing I/O (XLib can do this), or force the use of either
		770	<code>EVBACKEND_SELECT</code> or <code>EVBACKEND_POLL</code>, which don't suffer from this
		771	problem. Also note that it is quite easy to have your callback invoked
		772	when the readyness condition is no longer valid even when employing
		773	typical ways of handling events, so its a good idea to use non-blocking
		774	I/O unconditionally.</p>
441	</dd>	775	</dd>
442	</dl>	776	</dl>
		777	<p>Example: call <code>stdin_readable_cb</code> when STDIN_FILENO has become, well
		778	readable, but only once. Since it is likely line-buffered, you could
		779	attempt to read a whole line in the callback:</p>
		780	<pre> static void
		781	stdin_readable_cb (struct ev_loop loop, struct ev_io w, int revents)
		782	{
		783	ev_io_stop (loop, w);
		784	.. read from stdin here (or from w->fd) and haqndle any I/O errors
		785	}
443		786
		787	...
		788	struct ev_loop *loop = ev_default_init (0);
		789	struct ev_io stdin_readable;
		790	ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);
		791	ev_io_start (loop, &stdin_readable);
		792	ev_loop (loop, 0);
		793
		794
		795
		796
		797	</pre>
		798
444	</div>	799	</div>
445	<h2 id="struct_ev_timer_relative_and_optiona">struct ev_timer - relative and optionally recurring timeouts</h2>	800	<h2 id="code_ev_timer_code_relative_and_opti"><code>ev_timer</code> - relative and optionally recurring timeouts</h2>
446	<div id="struct_ev_timer_relative_and_optiona-2">	801	<div id="code_ev_timer_code_relative_and_opti-2">
447	<p>Timer watchers are simple relative timers that generate an event after a	802	<p>Timer watchers are simple relative timers that generate an event after a
448	given time, and optionally repeating in regular intervals after that.</p>	803	given time, and optionally repeating in regular intervals after that.</p>
449	<p>The timers are based on real time, that is, if you register an event that	804	<p>The timers are based on real time, that is, if you register an event that
450	times out after an hour and youreset your system clock to last years	805	times out after an hour and you reset your system clock to last years
451	time, it will still time out after (roughly) and hour. "Roughly" because	806	time, it will still time out after (roughly) and hour. "Roughly" because
452	detecting time jumps is hard, and soem inaccuracies are unavoidable (the	807	detecting time jumps is hard, and some inaccuracies are unavoidable (the
453	monotonic clock option helps a lot here).</p>	808	monotonic clock option helps a lot here).</p>
		809	<p>The relative timeouts are calculated relative to the <code>ev_now ()</code>
		810	time. This is usually the right thing as this timestamp refers to the time
		811	of the event triggering whatever timeout you are modifying/starting. If
		812	you suspect event processing to be delayed and you <i>need</i> to base the timeout
		813	on the current time, use something like this to adjust for this:</p>
		814	<pre> ev_timer_set (&timer, after + ev_now () - ev_time (), 0.);
		815
		816	</pre>
		817	<p>The callback is guarenteed to be invoked only when its timeout has passed,
		818	but if multiple timers become ready during the same loop iteration then
		819	order of execution is undefined.</p>
454	<dl>	820	<dl>
455	<dt>ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)</dt>	821	<dt>ev_timer_init (ev_timer *, callback, ev_tstamp after, ev_tstamp repeat)</dt>
456	<dt>ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)</dt>	822	<dt>ev_timer_set (ev_timer *, ev_tstamp after, ev_tstamp repeat)</dt>
457	<dd>	823	<dd>
458	<p>Configure the timer to trigger after <code>after</code> seconds. If <code>repeat</code> is	824	<p>Configure the timer to trigger after <code>after</code> seconds. If <code>repeat</code> is
…		…
460	timer will automatically be configured to trigger again <code>repeat</code> seconds	826	timer will automatically be configured to trigger again <code>repeat</code> seconds
461	later, again, and again, until stopped manually.</p>	827	later, again, and again, until stopped manually.</p>
462	<p>The timer itself will do a best-effort at avoiding drift, that is, if you	828	<p>The timer itself will do a best-effort at avoiding drift, that is, if you
463	configure a timer to trigger every 10 seconds, then it will trigger at	829	configure a timer to trigger every 10 seconds, then it will trigger at
464	exactly 10 second intervals. If, however, your program cannot keep up with	830	exactly 10 second intervals. If, however, your program cannot keep up with
465	the timer (ecause it takes longer than those 10 seconds to do stuff) the	831	the timer (because it takes longer than those 10 seconds to do stuff) the
466	timer will not fire more than once per event loop iteration.</p>	832	timer will not fire more than once per event loop iteration.</p>
467	</dd>	833	</dd>
468	<dt>ev_timer_again (loop)</dt>	834	<dt>ev_timer_again (loop)</dt>
469	<dd>	835	<dd>
470	<p>This will act as if the timer timed out and restart it again if it is	836	<p>This will act as if the timer timed out and restart it again if it is
…		…
474	value), or reset the running timer to the repeat value.</p>	840	value), or reset the running timer to the repeat value.</p>
475	<p>This sounds a bit complicated, but here is a useful and typical	841	<p>This sounds a bit complicated, but here is a useful and typical
476	example: Imagine you have a tcp connection and you want a so-called idle	842	example: Imagine you have a tcp connection and you want a so-called idle
477	timeout, that is, you want to be called when there have been, say, 60	843	timeout, that is, you want to be called when there have been, say, 60
478	seconds of inactivity on the socket. The easiest way to do this is to	844	seconds of inactivity on the socket. The easiest way to do this is to
479	configure an ev_timer with after=repeat=60 and calling ev_timer_again each	845	configure an <code>ev_timer</code> with after=repeat=60 and calling ev_timer_again each
480	time you successfully read or write some data. If you go into an idle	846	time you successfully read or write some data. If you go into an idle
481	state where you do not expect data to travel on the socket, you can stop	847	state where you do not expect data to travel on the socket, you can stop
482	the timer, and again will automatically restart it if need be.</p>	848	the timer, and again will automatically restart it if need be.</p>
483	</dd>	849	</dd>
484	</dl>	850	</dl>
		851	<p>Example: create a timer that fires after 60 seconds.</p>
		852	<pre> static void
		853	one_minute_cb (struct ev_loop loop, struct ev_timer w, int revents)
		854	{
		855	.. one minute over, w is actually stopped right here
		856	}
485		857
		858	struct ev_timer mytimer;
		859	ev_timer_init (&mytimer, one_minute_cb, 60., 0.);
		860	ev_timer_start (loop, &mytimer);
		861
		862	</pre>
		863	<p>Example: create a timeout timer that times out after 10 seconds of
		864	inactivity.</p>
		865	<pre> static void
		866	timeout_cb (struct ev_loop loop, struct ev_timer w, int revents)
		867	{
		868	.. ten seconds without any activity
		869	}
		870
		871	struct ev_timer mytimer;
		872	ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */
		873	ev_timer_again (&mytimer); /* start timer */
		874	ev_loop (loop, 0);
		875
		876	// and in some piece of code that gets executed on any "activity":
		877	// reset the timeout to start ticking again at 10 seconds
		878	ev_timer_again (&mytimer);
		879
		880
		881
		882
		883	</pre>
		884
486	</div>	885	</div>
487	<h2 id="ev_periodic_to_cron_or_not_to_cron_i">ev_periodic - to cron or not to cron it</h2>	886	<h2 id="code_ev_periodic_code_to_cron_or_not"><code>ev_periodic</code> - to cron or not to cron</h2>
488	<div id="ev_periodic_to_cron_or_not_to_cron_i-2">	887	<div id="code_ev_periodic_code_to_cron_or_not-2">
489	<p>Periodic watchers are also timers of a kind, but they are very versatile	888	<p>Periodic watchers are also timers of a kind, but they are very versatile
490	(and unfortunately a bit complex).</p>	889	(and unfortunately a bit complex).</p>
491	<p>Unlike ev_timer's, they are not based on real time (or relative time)	890	<p>Unlike <code>ev_timer</code>'s, they are not based on real time (or relative time)
492	but on wallclock time (absolute time). You can tell a periodic watcher	891	but on wallclock time (absolute time). You can tell a periodic watcher
493	to trigger "at" some specific point in time. For example, if you tell a	892	to trigger "at" some specific point in time. For example, if you tell a
494	periodic watcher to trigger in 10 seconds (by specifiying e.g. c<ev_now ()	893	periodic watcher to trigger in 10 seconds (by specifiying e.g. <code>ev_now ()
495	+ 10.>) and then reset your system clock to the last year, then it will	894	+ 10.</code>) and then reset your system clock to the last year, then it will
496	take a year to trigger the event (unlike an ev_timer, which would trigger	895	take a year to trigger the event (unlike an <code>ev_timer</code>, which would trigger
497	roughly 10 seconds later and of course not if you reset your system time	896	roughly 10 seconds later and of course not if you reset your system time
498	again).</p>	897	again).</p>
499	<p>They can also be used to implement vastly more complex timers, such as	898	<p>They can also be used to implement vastly more complex timers, such as
500	triggering an event on eahc midnight, local time.</p>	899	triggering an event on eahc midnight, local time.</p>
		900	<p>As with timers, the callback is guarenteed to be invoked only when the
		901	time (<code>at</code>) has been passed, but if multiple periodic timers become ready
		902	during the same loop iteration then order of execution is undefined.</p>
501	<dl>	903	<dl>
502	<dt>ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)</dt>	904	<dt>ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)</dt>
503	<dt>ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)</dt>	905	<dt>ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)</dt>
504	<dd>	906	<dd>
505	<p>Lots of arguments, lets sort it out... There are basically three modes of	907	<p>Lots of arguments, lets sort it out... There are basically three modes of
506	operation, and we will explain them from simplest to complex:</p>	908	operation, and we will explain them from simplest to complex:</p>
507
508
509
510
511	<p>	909	<p>
512	<dl>	910	<dl>
513	<dt>* absolute timer (interval = reschedule_cb = 0)</dt>	911	<dt>* absolute timer (interval = reschedule_cb = 0)</dt>
514	<dd>	912	<dd>
515	<p>In this configuration the watcher triggers an event at the wallclock time	913	<p>In this configuration the watcher triggers an event at the wallclock time
…		…
527	<pre> ev_periodic_set (&periodic, 0., 3600., 0);	925	<pre> ev_periodic_set (&periodic, 0., 3600., 0);
528		926
529	</pre>	927	</pre>
530	<p>This doesn't mean there will always be 3600 seconds in between triggers,	928	<p>This doesn't mean there will always be 3600 seconds in between triggers,
531	but only that the the callback will be called when the system time shows a	929	but only that the the callback will be called when the system time shows a
532	full hour (UTC), or more correct, when the system time is evenly divisible	930	full hour (UTC), or more correctly, when the system time is evenly divisible
533	by 3600.</p>	931	by 3600.</p>
534	<p>Another way to think about it (for the mathematically inclined) is that	932	<p>Another way to think about it (for the mathematically inclined) is that
535	ev_periodic will try to run the callback in this mode at the next possible	933	<code>ev_periodic</code> will try to run the callback in this mode at the next possible
536	time where <code>time = at (mod interval)</code>, regardless of any time jumps.</p>	934	time where <code>time = at (mod interval)</code>, regardless of any time jumps.</p>
537	</dd>	935	</dd>
538	<dt>* manual reschedule mode (reschedule_cb = callback)</dt>	936	<dt>* manual reschedule mode (reschedule_cb = callback)</dt>
539	<dd>	937	<dd>
540	<p>In this mode the values for <code>interval</code> and <code>at</code> are both being	938	<p>In this mode the values for <code>interval</code> and <code>at</code> are both being
541	ignored. Instead, each time the periodic watcher gets scheduled, the	939	ignored. Instead, each time the periodic watcher gets scheduled, the
542	reschedule callback will be called with the watcher as first, and the	940	reschedule callback will be called with the watcher as first, and the
543	current time as second argument.</p>	941	current time as second argument.</p>
544	<p>NOTE: <i>This callback MUST NOT stop or destroy the periodic or any other	942	<p>NOTE: <i>This callback MUST NOT stop or destroy any periodic watcher,
545	periodic watcher, ever, or make any event loop modificstions</i>. If you need	943	ever, or make any event loop modifications</i>. If you need to stop it,
546	to stop it, return 1e30 (or so, fudge fudge) and stop it afterwards.</p>	944	return <code>now + 1e30</code> (or so, fudge fudge) and stop it afterwards (e.g. by
		945	starting a prepare watcher).</p>
547	<p>Its prototype is c<ev_tstamp (reschedule_cb)(struct ev_periodic w,	946	<p>Its prototype is <code>ev_tstamp (reschedule_cb)(struct ev_periodic w,
548	ev_tstamp now)>, e.g.:</p>	947	ev_tstamp now)</code>, e.g.:</p>
549	<pre> static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now)	948	<pre> static ev_tstamp my_rescheduler (struct ev_periodic *w, ev_tstamp now)
550	{	949	{
551	return now + 60.;	950	return now + 60.;
552	}	951	}
553		952
554	</pre>	953	</pre>
555	<p>It must return the next time to trigger, based on the passed time value	954	<p>It must return the next time to trigger, based on the passed time value
556	(that is, the lowest time value larger than to the second argument). It	955	(that is, the lowest time value larger than to the second argument). It
557	will usually be called just before the callback will be triggered, but	956	will usually be called just before the callback will be triggered, but
558	might be called at other times, too.</p>	957	might be called at other times, too.</p>
		958	<p>NOTE: <i>This callback must always return a time that is later than the
		959	passed <code>now</code> value</i>. Not even <code>now</code> itself will do, it <i>must</i> be larger.</p>
559	<p>This can be used to create very complex timers, such as a timer that	960	<p>This can be used to create very complex timers, such as a timer that
560	triggers on each midnight, local time. To do this, you would calculate the	961	triggers on each midnight, local time. To do this, you would calculate the
561	next midnight after <code>now</code> and return the timestamp value for this. How you do this	962	next midnight after <code>now</code> and return the timestamp value for this. How
562	is, again, up to you (but it is not trivial).</p>	963	you do this is, again, up to you (but it is not trivial, which is the main
		964	reason I omitted it as an example).</p>
563	</dd>	965	</dd>
564	</dl>	966	</dl>
565	</p>	967	</p>
566	</dd>	968	</dd>
567	<dt>ev_periodic_again (loop, ev_periodic *)</dt>	969	<dt>ev_periodic_again (loop, ev_periodic *)</dt>
…		…
570	when you changed some parameters or the reschedule callback would return	972	when you changed some parameters or the reschedule callback would return
571	a different time than the last time it was called (e.g. in a crond like	973	a different time than the last time it was called (e.g. in a crond like
572	program when the crontabs have changed).</p>	974	program when the crontabs have changed).</p>
573	</dd>	975	</dd>
574	</dl>	976	</dl>
		977	<p>Example: call a callback every hour, or, more precisely, whenever the
		978	system clock is divisible by 3600. The callback invocation times have
		979	potentially a lot of jittering, but good long-term stability.</p>
		980	<pre> static void
		981	clock_cb (struct ev_loop loop, struct ev_io w, int revents)
		982	{
		983	... its now a full hour (UTC, or TAI or whatever your clock follows)
		984	}
575		985
		986	struct ev_periodic hourly_tick;
		987	ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);
		988	ev_periodic_start (loop, &hourly_tick);
		989
		990	</pre>
		991	<p>Example: the same as above, but use a reschedule callback to do it:</p>
		992	<pre> #include <math.h>
		993
		994	static ev_tstamp
		995	my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)
		996	{
		997	return fmod (now, 3600.) + 3600.;
		998	}
		999
		1000	ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);
		1001
		1002	</pre>
		1003	<p>Example: call a callback every hour, starting now:</p>
		1004	<pre> struct ev_periodic hourly_tick;
		1005	ev_periodic_init (&hourly_tick, clock_cb,
		1006	fmod (ev_now (loop), 3600.), 3600., 0);
		1007	ev_periodic_start (loop, &hourly_tick);
		1008
		1009
		1010
		1011
		1012	</pre>
		1013
576	</div>	1014	</div>
577	<h2 id="ev_signal_signal_me_when_a_signal_ge">ev_signal - signal me when a signal gets signalled</h2>	1015	<h2 id="code_ev_signal_code_signal_me_when_a"><code>ev_signal</code> - signal me when a signal gets signalled</h2>
578	<div id="ev_signal_signal_me_when_a_signal_ge-2">	1016	<div id="code_ev_signal_code_signal_me_when_a-2">
579	<p>Signal watchers will trigger an event when the process receives a specific	1017	<p>Signal watchers will trigger an event when the process receives a specific
580	signal one or more times. Even though signals are very asynchronous, libev	1018	signal one or more times. Even though signals are very asynchronous, libev
581	will try its best to deliver signals synchronously, i.e. as part of the	1019	will try it's best to deliver signals synchronously, i.e. as part of the
582	normal event processing, like any other event.</p>	1020	normal event processing, like any other event.</p>
583	<p>You cna configure as many watchers as you like per signal. Only when the	1021	<p>You can configure as many watchers as you like per signal. Only when the
584	first watcher gets started will libev actually register a signal watcher	1022	first watcher gets started will libev actually register a signal watcher
585	with the kernel (thus it coexists with your own signal handlers as long	1023	with the kernel (thus it coexists with your own signal handlers as long
586	as you don't register any with libev). Similarly, when the last signal	1024	as you don't register any with libev). Similarly, when the last signal
587	watcher for a signal is stopped libev will reset the signal handler to	1025	watcher for a signal is stopped libev will reset the signal handler to
588	SIG_DFL (regardless of what it was set to before).</p>	1026	SIG_DFL (regardless of what it was set to before).</p>
…		…
593	<p>Configures the watcher to trigger on the given signal number (usually one	1031	<p>Configures the watcher to trigger on the given signal number (usually one
594	of the <code>SIGxxx</code> constants).</p>	1032	of the <code>SIGxxx</code> constants).</p>
595	</dd>	1033	</dd>
596	</dl>	1034	</dl>
597		1035
		1036
		1037
		1038
		1039
598	</div>	1040	</div>
599	<h2 id="ev_child_wait_for_pid_status_changes">ev_child - wait for pid status changes</h2>	1041	<h2 id="code_ev_child_code_wait_for_pid_stat"><code>ev_child</code> - wait for pid status changes</h2>
600	<div id="ev_child_wait_for_pid_status_changes-2">	1042	<div id="code_ev_child_code_wait_for_pid_stat-2">
601	<p>Child watchers trigger when your process receives a SIGCHLD in response to	1043	<p>Child watchers trigger when your process receives a SIGCHLD in response to
602	some child status changes (most typically when a child of yours dies).</p>	1044	some child status changes (most typically when a child of yours dies).</p>
603	<dl>	1045	<dl>
604	<dt>ev_child_init (ev_child *, callback, int pid)</dt>	1046	<dt>ev_child_init (ev_child *, callback, int pid)</dt>
605	<dt>ev_child_set (ev_child *, int pid)</dt>	1047	<dt>ev_child_set (ev_child *, int pid)</dt>
606	<dd>	1048	<dd>
607	<p>Configures the watcher to wait for status changes of process <code>pid</code> (or	1049	<p>Configures the watcher to wait for status changes of process <code>pid</code> (or
608	<i>any</i> process if <code>pid</code> is specified as <code>0</code>). The callback can look	1050	<i>any</i> process if <code>pid</code> is specified as <code>0</code>). The callback can look
609	at the <code>rstatus</code> member of the <code>ev_child</code> watcher structure to see	1051	at the <code>rstatus</code> member of the <code>ev_child</code> watcher structure to see
610	the status word (use the macros from <code>sys/wait.h</code>). The <code>rpid</code> member	1052	the status word (use the macros from <code>sys/wait.h</code> and see your systems
		1053	<code>waitpid</code> documentation). The <code>rpid</code> member contains the pid of the
611	contains the pid of the process causing the status change.</p>	1054	process causing the status change.</p>
612	</dd>	1055	</dd>
613	</dl>	1056	</dl>
		1057	<p>Example: try to exit cleanly on SIGINT and SIGTERM.</p>
		1058	<pre> static void
		1059	sigint_cb (struct ev_loop loop, struct ev_signal w, int revents)
		1060	{
		1061	ev_unloop (loop, EVUNLOOP_ALL);
		1062	}
614		1063
		1064	struct ev_signal signal_watcher;
		1065	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);
		1066	ev_signal_start (loop, &sigint_cb);
		1067
		1068
		1069
		1070
		1071	</pre>
		1072
615	</div>	1073	</div>
616	<h2 id="ev_idle_when_you_ve_got_nothing_bett">ev_idle - when you've got nothing better to do</h2>	1074	<h2 id="code_ev_idle_code_when_you_ve_got_no"><code>ev_idle</code> - when you've got nothing better to do</h2>
617	<div id="ev_idle_when_you_ve_got_nothing_bett-2">	1075	<div id="code_ev_idle_code_when_you_ve_got_no-2">
618	<p>Idle watchers trigger events when there are no other I/O or timer (or	1076	<p>Idle watchers trigger events when there are no other events are pending
619	periodic) events pending. That is, as long as your process is busy	1077	(prepare, check and other idle watchers do not count). That is, as long
620	handling sockets or timeouts it will not be called. But when your process	1078	as your process is busy handling sockets or timeouts (or even signals,
621	is idle all idle watchers are being called again and again - until	1079	imagine) it will not be triggered. But when your process is idle all idle
		1080	watchers are being called again and again, once per event loop iteration -
622	stopped, that is, or your process receives more events.</p>	1081	until stopped, that is, or your process receives more events and becomes
		1082	busy.</p>
623	<p>The most noteworthy effect is that as long as any idle watchers are	1083	<p>The most noteworthy effect is that as long as any idle watchers are
624	active, the process will not block when waiting for new events.</p>	1084	active, the process will not block when waiting for new events.</p>
625	<p>Apart from keeping your process non-blocking (which is a useful	1085	<p>Apart from keeping your process non-blocking (which is a useful
626	effect on its own sometimes), idle watchers are a good place to do	1086	effect on its own sometimes), idle watchers are a good place to do
627	"pseudo-background processing", or delay processing stuff to after the	1087	"pseudo-background processing", or delay processing stuff to after the
…		…
632	<p>Initialises and configures the idle watcher - it has no parameters of any	1092	<p>Initialises and configures the idle watcher - it has no parameters of any
633	kind. There is a <code>ev_idle_set</code> macro, but using it is utterly pointless,	1093	kind. There is a <code>ev_idle_set</code> macro, but using it is utterly pointless,
634	believe me.</p>	1094	believe me.</p>
635	</dd>	1095	</dd>
636	</dl>	1096	</dl>
		1097	<p>Example: dynamically allocate an <code>ev_idle</code>, start it, and in the
		1098	callback, free it. Alos, use no error checking, as usual.</p>
		1099	<pre> static void
		1100	idle_cb (struct ev_loop loop, struct ev_idle w, int revents)
		1101	{
		1102	free (w);
		1103	// now do something you wanted to do when the program has
		1104	// no longer asnything immediate to do.
		1105	}
637		1106
		1107	struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle));
		1108	ev_idle_init (idle_watcher, idle_cb);
		1109	ev_idle_start (loop, idle_cb);
		1110
		1111
		1112
		1113
		1114	</pre>
		1115
638	</div>	1116	</div>
639	<h2 id="prepare_and_check_your_hooks_into_th">prepare and check - your hooks into the event loop</h2>	1117	<h2 id="code_ev_prepare_code_and_code_ev_che"><code>ev_prepare</code> and <code>ev_check</code> - customise your event loop</h2>
640	<div id="prepare_and_check_your_hooks_into_th-2">	1118	<div id="code_ev_prepare_code_and_code_ev_che-2">
641	<p>Prepare and check watchers usually (but not always) are used in	1119	<p>Prepare and check watchers are usually (but not always) used in tandem:
642	tandom. Prepare watchers get invoked before the process blocks and check	1120	prepare watchers get invoked before the process blocks and check watchers
643	watchers afterwards.</p>	1121	afterwards.</p>
644	<p>Their main purpose is to integrate other event mechanisms into libev. This	1122	<p>Their main purpose is to integrate other event mechanisms into libev and
645	could be used, for example, to track variable changes, implement your own	1123	their use is somewhat advanced. This could be used, for example, to track
646	watchers, integrate net-snmp or a coroutine library and lots more.</p>	1124	variable changes, implement your own watchers, integrate net-snmp or a
		1125	coroutine library and lots more.</p>
647	<p>This is done by examining in each prepare call which file descriptors need	1126	<p>This is done by examining in each prepare call which file descriptors need
648	to be watched by the other library, registering ev_io watchers for them	1127	to be watched by the other library, registering <code>ev_io</code> watchers for
649	and starting an ev_timer watcher for any timeouts (many libraries provide	1128	them and starting an <code>ev_timer</code> watcher for any timeouts (many libraries
650	just this functionality). Then, in the check watcher you check for any	1129	provide just this functionality). Then, in the check watcher you check for
651	events that occured (by making your callbacks set soem flags for example)	1130	any events that occured (by checking the pending status of all watchers
652	and call back into the library.</p>	1131	and stopping them) and call back into the library. The I/O and timer
		1132	callbacks will never actually be called (but must be valid nevertheless,
		1133	because you never know, you know?).</p>
653	<p>As another example, the perl Coro module uses these hooks to integrate	1134	<p>As another example, the Perl Coro module uses these hooks to integrate
654	coroutines into libev programs, by yielding to other active coroutines	1135	coroutines into libev programs, by yielding to other active coroutines
655	during each prepare and only letting the process block if no coroutines	1136	during each prepare and only letting the process block if no coroutines
656	are ready to run.</p>	1137	are ready to run (it's actually more complicated: it only runs coroutines
		1138	with priority higher than or equal to the event loop and one coroutine
		1139	of lower priority, but only once, using idle watchers to keep the event
		1140	loop from blocking if lower-priority coroutines are active, thus mapping
		1141	low-priority coroutines to idle/background tasks).</p>
657	<dl>	1142	<dl>
658	<dt>ev_prepare_init (ev_prepare *, callback)</dt>	1143	<dt>ev_prepare_init (ev_prepare *, callback)</dt>
659	<dt>ev_check_init (ev_check *, callback)</dt>	1144	<dt>ev_check_init (ev_check *, callback)</dt>
660	<dd>	1145	<dd>
661	<p>Initialises and configures the prepare or check watcher - they have no	1146	<p>Initialises and configures the prepare or check watcher - they have no
662	parameters of any kind. There are <code>ev_prepare_set</code> and <code>ev_check_set</code>	1147	parameters of any kind. There are <code>ev_prepare_set</code> and <code>ev_check_set</code>
663	macros, but using them is utterly, utterly pointless.</p>	1148	macros, but using them is utterly, utterly and completely pointless.</p>
664	</dd>	1149	</dd>
665	</dl>	1150	</dl>
		1151	<p>Example: TODO.</p>
		1152
		1153
		1154
		1155
		1156
		1157	</div>
		1158	<h2 id="code_ev_embed_code_when_one_backend_"><code>ev_embed</code> - when one backend isn't enough</h2>
		1159	<div id="code_ev_embed_code_when_one_backend_-2">
		1160	<p>This is a rather advanced watcher type that lets you embed one event loop
		1161	into another (currently only <code>ev_io</code> events are supported in the embedded
		1162	loop, other types of watchers might be handled in a delayed or incorrect
		1163	fashion and must not be used).</p>
		1164	<p>There are primarily two reasons you would want that: work around bugs and
		1165	prioritise I/O.</p>
		1166	<p>As an example for a bug workaround, the kqueue backend might only support
		1167	sockets on some platform, so it is unusable as generic backend, but you
		1168	still want to make use of it because you have many sockets and it scales
		1169	so nicely. In this case, you would create a kqueue-based loop and embed it
		1170	into your default loop (which might use e.g. poll). Overall operation will
		1171	be a bit slower because first libev has to poll and then call kevent, but
		1172	at least you can use both at what they are best.</p>
		1173	<p>As for prioritising I/O: rarely you have the case where some fds have
		1174	to be watched and handled very quickly (with low latency), and even
		1175	priorities and idle watchers might have too much overhead. In this case
		1176	you would put all the high priority stuff in one loop and all the rest in
		1177	a second one, and embed the second one in the first.</p>
		1178	<p>As long as the watcher is active, the callback will be invoked every time
		1179	there might be events pending in the embedded loop. The callback must then
		1180	call <code>ev_embed_sweep (mainloop, watcher)</code> to make a single sweep and invoke
		1181	their callbacks (you could also start an idle watcher to give the embedded
		1182	loop strictly lower priority for example). You can also set the callback
		1183	to <code>0</code>, in which case the embed watcher will automatically execute the
		1184	embedded loop sweep.</p>
		1185	<p>As long as the watcher is started it will automatically handle events. The
		1186	callback will be invoked whenever some events have been handled. You can
		1187	set the callback to <code>0</code> to avoid having to specify one if you are not
		1188	interested in that.</p>
		1189	<p>Also, there have not currently been made special provisions for forking:
		1190	when you fork, you not only have to call <code>ev_loop_fork</code> on both loops,
		1191	but you will also have to stop and restart any <code>ev_embed</code> watchers
		1192	yourself.</p>
		1193	<p>Unfortunately, not all backends are embeddable, only the ones returned by
		1194	<code>ev_embeddable_backends</code> are, which, unfortunately, does not include any
		1195	portable one.</p>
		1196	<p>So when you want to use this feature you will always have to be prepared
		1197	that you cannot get an embeddable loop. The recommended way to get around
		1198	this is to have a separate variables for your embeddable loop, try to
		1199	create it, and if that fails, use the normal loop for everything:</p>
		1200	<pre> struct ev_loop *loop_hi = ev_default_init (0);
		1201	struct ev_loop *loop_lo = 0;
		1202	struct ev_embed embed;
		1203
		1204	// see if there is a chance of getting one that works
		1205	// (remember that a flags value of 0 means autodetection)
		1206	loop_lo = ev_embeddable_backends () & ev_recommended_backends ()
		1207	? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ())
		1208	: 0;
		1209
		1210	// if we got one, then embed it, otherwise default to loop_hi
		1211	if (loop_lo)
		1212	{
		1213	ev_embed_init (&embed, 0, loop_lo);
		1214	ev_embed_start (loop_hi, &embed);
		1215	}
		1216	else
		1217	loop_lo = loop_hi;
		1218
		1219	</pre>
		1220	<dl>
		1221	<dt>ev_embed_init (ev_embed , callback, struct ev_loop embedded_loop)</dt>
		1222	<dt>ev_embed_set (ev_embed , callback, struct ev_loop embedded_loop)</dt>
		1223	<dd>
		1224	<p>Configures the watcher to embed the given loop, which must be
		1225	embeddable. If the callback is <code>0</code>, then <code>ev_embed_sweep</code> will be
		1226	invoked automatically, otherwise it is the responsibility of the callback
		1227	to invoke it (it will continue to be called until the sweep has been done,
		1228	if you do not want thta, you need to temporarily stop the embed watcher).</p>
		1229	</dd>
		1230	<dt>ev_embed_sweep (loop, ev_embed *)</dt>
		1231	<dd>
		1232	<p>Make a single, non-blocking sweep over the embedded loop. This works
		1233	similarly to <code>ev_loop (embedded_loop, EVLOOP_NONBLOCK)</code>, but in the most
		1234	apropriate way for embedded loops.</p>
		1235	</dd>
		1236	</dl>
		1237
		1238
		1239
		1240
666		1241
667	</div>	1242	</div>
668	<h1 id="OTHER_FUNCTIONS">OTHER FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p>	1243	<h1 id="OTHER_FUNCTIONS">OTHER FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p>
669	<div id="OTHER_FUNCTIONS_CONTENT">	1244	<div id="OTHER_FUNCTIONS_CONTENT">
670	<p>There are some other fucntions of possible interest. Described. Here. Now.</p>	1245	<p>There are some other functions of possible interest. Described. Here. Now.</p>
671	<dl>	1246	<dl>
672	<dt>ev_once (loop, int fd, int events, ev_tstamp timeout, callback)</dt>	1247	<dt>ev_once (loop, int fd, int events, ev_tstamp timeout, callback)</dt>
673	<dd>	1248	<dd>
674	<p>This function combines a simple timer and an I/O watcher, calls your	1249	<p>This function combines a simple timer and an I/O watcher, calls your
675	callback on whichever event happens first and automatically stop both	1250	callback on whichever event happens first and automatically stop both
676	watchers. This is useful if you want to wait for a single event on an fd	1251	watchers. This is useful if you want to wait for a single event on an fd
677	or timeout without havign to allocate/configure/start/stop/free one or	1252	or timeout without having to allocate/configure/start/stop/free one or
678	more watchers yourself.</p>	1253	more watchers yourself.</p>
679	<p>If <code>fd</code> is less than 0, then no I/O watcher will be started and events is	1254	<p>If <code>fd</code> is less than 0, then no I/O watcher will be started and events
680	ignored. Otherwise, an ev_io watcher for the given <code>fd</code> and <code>events</code> set	1255	is being ignored. Otherwise, an <code>ev_io</code> watcher for the given <code>fd</code> and
681	will be craeted and started.</p>	1256	<code>events</code> set will be craeted and started.</p>
682	<p>If <code>timeout</code> is less than 0, then no timeout watcher will be	1257	<p>If <code>timeout</code> is less than 0, then no timeout watcher will be
683	started. Otherwise an ev_timer watcher with after = <code>timeout</code> (and repeat	1258	started. Otherwise an <code>ev_timer</code> watcher with after = <code>timeout</code> (and
684	= 0) will be started.</p>	1259	repeat = 0) will be started. While <code>0</code> is a valid timeout, it is of
		1260	dubious value.</p>
685	<p>The callback has the type <code>void (cb)(int revents, void arg)</code> and	1261	<p>The callback has the type <code>void (cb)(int revents, void arg)</code> and gets
686	gets passed an events set (normally a combination of EV_ERROR, EV_READ,	1262	passed an <code>revents</code> set like normal event callbacks (a combination of
687	EV_WRITE or EV_TIMEOUT) and the <code>arg</code> value passed to <code>ev_once</code>:</p>	1263	<code>EV_ERROR</code>, <code>EV_READ</code>, <code>EV_WRITE</code> or <code>EV_TIMEOUT</code>) and the <code>arg</code>
		1264	value passed to <code>ev_once</code>:</p>
688	<pre> static void stdin_ready (int revents, void *arg)	1265	<pre> static void stdin_ready (int revents, void *arg)
689	{	1266	{
690	if (revents & EV_TIMEOUT)	1267	if (revents & EV_TIMEOUT)
691	/* doh, nothing entered */	1268	/* doh, nothing entered */;
692	else if (revents & EV_READ)	1269	else if (revents & EV_READ)
693	/* stdin might have data for us, joy! */	1270	/* stdin might have data for us, joy! */;
694	}	1271	}
695		1272
696	ev_once (STDIN_FILENO, EV_READm 10., stdin_ready, 0);	1273	ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);
697		1274
698	</pre>	1275	</pre>
699	</dd>	1276	</dd>
700	<dt>ev_feed_event (loop, watcher, int events)</dt>	1277	<dt>ev_feed_event (ev_loop , watcher , int revents)</dt>
701	<dd>	1278	<dd>
702	<p>Feeds the given event set into the event loop, as if the specified event	1279	<p>Feeds the given event set into the event loop, as if the specified event
703	has happened for the specified watcher (which must be a pointer to an	1280	had happened for the specified watcher (which must be a pointer to an
704	initialised but not necessarily active event watcher).</p>	1281	initialised but not necessarily started event watcher).</p>
705	</dd>	1282	</dd>
706	<dt>ev_feed_fd_event (loop, int fd, int revents)</dt>	1283	<dt>ev_feed_fd_event (ev_loop *, int fd, int revents)</dt>
707	<dd>	1284	<dd>
708	<p>Feed an event on the given fd, as if a file descriptor backend detected it.</p>	1285	<p>Feed an event on the given fd, as if a file descriptor backend detected
		1286	the given events it.</p>
709	</dd>	1287	</dd>
710	<dt>ev_feed_signal_event (loop, int signum)</dt>	1288	<dt>ev_feed_signal_event (ev_loop *loop, int signum)</dt>
711	<dd>	1289	<dd>
712	<p>Feed an event as if the given signal occured (loop must be the default loop!).</p>	1290	<p>Feed an event as if the given signal occured (<code>loop</code> must be the default
		1291	loop!).</p>
713	</dd>	1292	</dd>
714	</dl>	1293	</dl>
		1294
		1295
		1296
		1297
		1298
		1299	</div>
		1300	<h1 id="LIBEVENT_EMULATION">LIBEVENT EMULATION</h1><p><a href="#TOP" class="toplink">Top</a></p>
		1301	<div id="LIBEVENT_EMULATION_CONTENT">
		1302	<p>Libev offers a compatibility emulation layer for libevent. It cannot
		1303	emulate the internals of libevent, so here are some usage hints:</p>
		1304	<dl>
		1305	<dt>* Use it by including <event.h>, as usual.</dt>
		1306	<dt>* The following members are fully supported: ev_base, ev_callback,
		1307	ev_arg, ev_fd, ev_res, ev_events.</dt>
		1308	<dt>* Avoid using ev_flags and the EVLIST_*-macros, while it is
		1309	maintained by libev, it does not work exactly the same way as in libevent (consider
		1310	it a private API).</dt>
		1311	<dt>* Priorities are not currently supported. Initialising priorities
		1312	will fail and all watchers will have the same priority, even though there
		1313	is an ev_pri field.</dt>
		1314	<dt>* Other members are not supported.</dt>
		1315	<dt>* The libev emulation is <i>not</i> ABI compatible to libevent, you need
		1316	to use the libev header file and library.</dt>
		1317	</dl>
		1318
		1319	</div>
		1320	<h1 id="C_SUPPORT">C++ SUPPORT</h1><p><a href="#TOP" class="toplink">Top</a></p>
		1321	<div id="C_SUPPORT_CONTENT">
		1322	<p>Libev comes with some simplistic wrapper classes for C++ that mainly allow
		1323	you to use some convinience methods to start/stop watchers and also change
		1324	the callback model to a model using method callbacks on objects.</p>
		1325	<p>To use it,</p>
		1326	<pre> #include <ev++.h>
		1327
		1328	</pre>
		1329	<p>(it is not installed by default). This automatically includes <cite>ev.h</cite>
		1330	and puts all of its definitions (many of them macros) into the global
		1331	namespace. All C++ specific things are put into the <code>ev</code> namespace.</p>
		1332	<p>It should support all the same embedding options as <cite>ev.h</cite>, most notably
		1333	<code>EV_MULTIPLICITY</code>.</p>
		1334	<p>Here is a list of things available in the <code>ev</code> namespace:</p>
		1335	<dl>
		1336	<dt><code>ev::READ</code>, <code>ev::WRITE</code> etc.</dt>
		1337	<dd>
		1338	<p>These are just enum values with the same values as the <code>EV_READ</code> etc.
		1339	macros from <cite>ev.h</cite>.</p>
		1340	</dd>
		1341	<dt><code>ev::tstamp</code>, <code>ev::now</code></dt>
		1342	<dd>
		1343	<p>Aliases to the same types/functions as with the <code>ev_</code> prefix.</p>
		1344	</dd>
		1345	<dt><code>ev::io</code>, <code>ev::timer</code>, <code>ev::periodic</code>, <code>ev::idle</code>, <code>ev::sig</code> etc.</dt>
		1346	<dd>
		1347	<p>For each <code>ev_TYPE</code> watcher in <cite>ev.h</cite> there is a corresponding class of
		1348	the same name in the <code>ev</code> namespace, with the exception of <code>ev_signal</code>
		1349	which is called <code>ev::sig</code> to avoid clashes with the <code>signal</code> macro
		1350	defines by many implementations.</p>
		1351	<p>All of those classes have these methods:</p>
		1352	<p>
		1353	<dl>
		1354	<dt>ev::TYPE::TYPE (object , object::method )</dt>
		1355	<dt>ev::TYPE::TYPE (object , object::method , struct ev_loop *)</dt>
		1356	<dt>ev::TYPE::~TYPE</dt>
		1357	<dd>
		1358	<p>The constructor takes a pointer to an object and a method pointer to
		1359	the event handler callback to call in this class. The constructor calls
		1360	<code>ev_init</code> for you, which means you have to call the <code>set</code> method
		1361	before starting it. If you do not specify a loop then the constructor
		1362	automatically associates the default loop with this watcher.</p>
		1363	<p>The destructor automatically stops the watcher if it is active.</p>
		1364	</dd>
		1365	<dt>w->set (struct ev_loop *)</dt>
		1366	<dd>
		1367	<p>Associates a different <code>struct ev_loop</code> with this watcher. You can only
		1368	do this when the watcher is inactive (and not pending either).</p>
		1369	</dd>
		1370	<dt>w->set ([args])</dt>
		1371	<dd>
		1372	<p>Basically the same as <code>ev_TYPE_set</code>, with the same args. Must be
		1373	called at least once. Unlike the C counterpart, an active watcher gets
		1374	automatically stopped and restarted.</p>
		1375	</dd>
		1376	<dt>w->start ()</dt>
		1377	<dd>
		1378	<p>Starts the watcher. Note that there is no <code>loop</code> argument as the
		1379	constructor already takes the loop.</p>
		1380	</dd>
		1381	<dt>w->stop ()</dt>
		1382	<dd>
		1383	<p>Stops the watcher if it is active. Again, no <code>loop</code> argument.</p>
		1384	</dd>
		1385	<dt>w->again () <code>ev::timer</code>, <code>ev::periodic</code> only</dt>
		1386	<dd>
		1387	<p>For <code>ev::timer</code> and <code>ev::periodic</code>, this invokes the corresponding
		1388	<code>ev_TYPE_again</code> function.</p>
		1389	</dd>
		1390	<dt>w->sweep () <code>ev::embed</code> only</dt>
		1391	<dd>
		1392	<p>Invokes <code>ev_embed_sweep</code>.</p>
		1393	</dd>
		1394	</dl>
		1395	</p>
		1396	</dd>
		1397	</dl>
		1398	<p>Example: Define a class with an IO and idle watcher, start one of them in
		1399	the constructor.</p>
		1400	<pre> class myclass
		1401	{
		1402	ev_io io; void io_cb (ev::io &w, int revents);
		1403	ev_idle idle void idle_cb (ev::idle &w, int revents);
		1404
		1405	myclass ();
		1406	}
		1407
		1408	myclass::myclass (int fd)
		1409	: io (this, &myclass::io_cb),
		1410	idle (this, &myclass::idle_cb)
		1411	{
		1412	io.start (fd, ev::READ);
		1413	}
		1414
		1415	</pre>
		1416
		1417	</div>
		1418	<h1 id="EMBEDDING">EMBEDDING</h1><p><a href="#TOP" class="toplink">Top</a></p>
		1419	<div id="EMBEDDING_CONTENT">
		1420	<p>Libev can (and often is) directly embedded into host
		1421	applications. Examples of applications that embed it include the Deliantra
		1422	Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe)
		1423	and rxvt-unicode.</p>
		1424	<p>The goal is to enable you to just copy the neecssary files into your
		1425	source directory without having to change even a single line in them, so
		1426	you can easily upgrade by simply copying (or having a checked-out copy of
		1427	libev somewhere in your source tree).</p>
		1428
		1429	</div>
		1430	<h2 id="FILESETS">FILESETS</h2>
		1431	<div id="FILESETS_CONTENT">
		1432	<p>Depending on what features you need you need to include one or more sets of files
		1433	in your app.</p>
		1434
		1435	</div>
		1436	<h3 id="CORE_EVENT_LOOP">CORE EVENT LOOP</h3>
		1437	<div id="CORE_EVENT_LOOP_CONTENT">
		1438	<p>To include only the libev core (all the <code>ev_*</code> functions), with manual
		1439	configuration (no autoconf):</p>
		1440	<pre> #define EV_STANDALONE 1
		1441	#include "ev.c"
		1442
		1443	</pre>
		1444	<p>This will automatically include <cite>ev.h</cite>, too, and should be done in a
		1445	single C source file only to provide the function implementations. To use
		1446	it, do the same for <cite>ev.h</cite> in all files wishing to use this API (best
		1447	done by writing a wrapper around <cite>ev.h</cite> that you can include instead and
		1448	where you can put other configuration options):</p>
		1449	<pre> #define EV_STANDALONE 1
		1450	#include "ev.h"
		1451
		1452	</pre>
		1453	<p>Both header files and implementation files can be compiled with a C++
		1454	compiler (at least, thats a stated goal, and breakage will be treated
		1455	as a bug).</p>
		1456	<p>You need the following files in your source tree, or in a directory
		1457	in your include path (e.g. in libev/ when using -Ilibev):</p>
		1458	<pre> ev.h
		1459	ev.c
		1460	ev_vars.h
		1461	ev_wrap.h
		1462
		1463	ev_win32.c required on win32 platforms only
		1464
		1465	ev_select.c only when select backend is enabled (which is is by default)
		1466	ev_poll.c only when poll backend is enabled (disabled by default)
		1467	ev_epoll.c only when the epoll backend is enabled (disabled by default)
		1468	ev_kqueue.c only when the kqueue backend is enabled (disabled by default)
		1469	ev_port.c only when the solaris port backend is enabled (disabled by default)
		1470
		1471	</pre>
		1472	<p><cite>ev.c</cite> includes the backend files directly when enabled, so you only need
		1473	to compile a single file.</p>
		1474
		1475	</div>
		1476	<h3 id="LIBEVENT_COMPATIBILITY_API">LIBEVENT COMPATIBILITY API</h3>
		1477	<div id="LIBEVENT_COMPATIBILITY_API_CONTENT">
		1478	<p>To include the libevent compatibility API, also include:</p>
		1479	<pre> #include "event.c"
		1480
		1481	</pre>
		1482	<p>in the file including <cite>ev.c</cite>, and:</p>
		1483	<pre> #include "event.h"
		1484
		1485	</pre>
		1486	<p>in the files that want to use the libevent API. This also includes <cite>ev.h</cite>.</p>
		1487	<p>You need the following additional files for this:</p>
		1488	<pre> event.h
		1489	event.c
		1490
		1491	</pre>
		1492
		1493	</div>
		1494	<h3 id="AUTOCONF_SUPPORT">AUTOCONF SUPPORT</h3>
		1495	<div id="AUTOCONF_SUPPORT_CONTENT">
		1496	<p>Instead of using <code>EV_STANDALONE=1</code> and providing your config in
		1497	whatever way you want, you can also <code>m4_include([libev.m4])</code> in your
		1498	<cite>configure.ac</cite> and leave <code>EV_STANDALONE</code> off. <cite>ev.c</cite> will then include
		1499	<cite>config.h</cite> and configure itself accordingly.</p>
		1500	<p>For this of course you need the m4 file:</p>
		1501	<pre> libev.m4
		1502
		1503	</pre>
		1504
		1505	</div>
		1506	<h2 id="PREPROCESSOR_SYMBOLS_MACROS">PREPROCESSOR SYMBOLS/MACROS</h2>
		1507	<div id="PREPROCESSOR_SYMBOLS_MACROS_CONTENT">
		1508	<p>Libev can be configured via a variety of preprocessor symbols you have to define
		1509	before including any of its files. The default is not to build for multiplicity
		1510	and only include the select backend.</p>
		1511	<dl>
		1512	<dt>EV_STANDALONE</dt>
		1513	<dd>
		1514	<p>Must always be <code>1</code> if you do not use autoconf configuration, which
		1515	keeps libev from including <cite>config.h</cite>, and it also defines dummy
		1516	implementations for some libevent functions (such as logging, which is not
		1517	supported). It will also not define any of the structs usually found in
		1518	<cite>event.h</cite> that are not directly supported by the libev core alone.</p>
		1519	</dd>
		1520	<dt>EV_USE_MONOTONIC</dt>
		1521	<dd>
		1522	<p>If defined to be <code>1</code>, libev will try to detect the availability of the
		1523	monotonic clock option at both compiletime and runtime. Otherwise no use
		1524	of the monotonic clock option will be attempted. If you enable this, you
		1525	usually have to link against librt or something similar. Enabling it when
		1526	the functionality isn't available is safe, though, althoguh you have
		1527	to make sure you link against any libraries where the <code>clock_gettime</code>
		1528	function is hiding in (often <cite>-lrt</cite>).</p>
		1529	</dd>
		1530	<dt>EV_USE_REALTIME</dt>
		1531	<dd>
		1532	<p>If defined to be <code>1</code>, libev will try to detect the availability of the
		1533	realtime clock option at compiletime (and assume its availability at
		1534	runtime if successful). Otherwise no use of the realtime clock option will
		1535	be attempted. This effectively replaces <code>gettimeofday</code> by <code>clock_get
		1536	(CLOCK_REALTIME, ...)</code> and will not normally affect correctness. See tzhe note about libraries
		1537	in the description of <code>EV_USE_MONOTONIC</code>, though.</p>
		1538	</dd>
		1539	<dt>EV_USE_SELECT</dt>
		1540	<dd>
		1541	<p>If undefined or defined to be <code>1</code>, libev will compile in support for the
		1542	<code>select</code>(2) backend. No attempt at autodetection will be done: if no
		1543	other method takes over, select will be it. Otherwise the select backend
		1544	will not be compiled in.</p>
		1545	</dd>
		1546	<dt>EV_SELECT_USE_FD_SET</dt>
		1547	<dd>
		1548	<p>If defined to <code>1</code>, then the select backend will use the system <code>fd_set</code>
		1549	structure. This is useful if libev doesn't compile due to a missing
		1550	<code>NFDBITS</code> or <code>fd_mask</code> definition or it misguesses the bitset layout on
		1551	exotic systems. This usually limits the range of file descriptors to some
		1552	low limit such as 1024 or might have other limitations (winsocket only
		1553	allows 64 sockets). The <code>FD_SETSIZE</code> macro, set before compilation, might
		1554	influence the size of the <code>fd_set</code> used.</p>
		1555	</dd>
		1556	<dt>EV_SELECT_IS_WINSOCKET</dt>
		1557	<dd>
		1558	<p>When defined to <code>1</code>, the select backend will assume that
		1559	select/socket/connect etc. don't understand file descriptors but
		1560	wants osf handles on win32 (this is the case when the select to
		1561	be used is the winsock select). This means that it will call
		1562	<code>_get_osfhandle</code> on the fd to convert it to an OS handle. Otherwise,
		1563	it is assumed that all these functions actually work on fds, even
		1564	on win32. Should not be defined on non-win32 platforms.</p>
		1565	</dd>
		1566	<dt>EV_USE_POLL</dt>
		1567	<dd>
		1568	<p>If defined to be <code>1</code>, libev will compile in support for the <code>poll</code>(2)
		1569	backend. Otherwise it will be enabled on non-win32 platforms. It
		1570	takes precedence over select.</p>
		1571	</dd>
		1572	<dt>EV_USE_EPOLL</dt>
		1573	<dd>
		1574	<p>If defined to be <code>1</code>, libev will compile in support for the Linux
		1575	<code>epoll</code>(7) backend. Its availability will be detected at runtime,
		1576	otherwise another method will be used as fallback. This is the
		1577	preferred backend for GNU/Linux systems.</p>
		1578	</dd>
		1579	<dt>EV_USE_KQUEUE</dt>
		1580	<dd>
		1581	<p>If defined to be <code>1</code>, libev will compile in support for the BSD style
		1582	<code>kqueue</code>(2) backend. Its actual availability will be detected at runtime,
		1583	otherwise another method will be used as fallback. This is the preferred
		1584	backend for BSD and BSD-like systems, although on most BSDs kqueue only
		1585	supports some types of fds correctly (the only platform we found that
		1586	supports ptys for example was NetBSD), so kqueue might be compiled in, but
		1587	not be used unless explicitly requested. The best way to use it is to find
		1588	out wether kqueue supports your type of fd properly and use an embedded
		1589	kqueue loop.</p>
		1590	</dd>
		1591	<dt>EV_USE_PORT</dt>
		1592	<dd>
		1593	<p>If defined to be <code>1</code>, libev will compile in support for the Solaris
		1594	10 port style backend. Its availability will be detected at runtime,
		1595	otherwise another method will be used as fallback. This is the preferred
		1596	backend for Solaris 10 systems.</p>
		1597	</dd>
		1598	<dt>EV_USE_DEVPOLL</dt>
		1599	<dd>
		1600	<p>reserved for future expansion, works like the USE symbols above.</p>
		1601	</dd>
		1602	<dt>EV_H</dt>
		1603	<dd>
		1604	<p>The name of the <cite>ev.h</cite> header file used to include it. The default if
		1605	undefined is <code><ev.h></code> in <cite>event.h</cite> and <code>"ev.h"</code> in <cite>ev.c</cite>. This
		1606	can be used to virtually rename the <cite>ev.h</cite> header file in case of conflicts.</p>
		1607	</dd>
		1608	<dt>EV_CONFIG_H</dt>
		1609	<dd>
		1610	<p>If <code>EV_STANDALONE</code> isn't <code>1</code>, this variable can be used to override
		1611	<cite>ev.c</cite>'s idea of where to find the <cite>config.h</cite> file, similarly to
		1612	<code>EV_H</code>, above.</p>
		1613	</dd>
		1614	<dt>EV_EVENT_H</dt>
		1615	<dd>
		1616	<p>Similarly to <code>EV_H</code>, this macro can be used to override <cite>event.c</cite>'s idea
		1617	of how the <cite>event.h</cite> header can be found.</p>
		1618	</dd>
		1619	<dt>EV_PROTOTYPES</dt>
		1620	<dd>
		1621	<p>If defined to be <code>0</code>, then <cite>ev.h</cite> will not define any function
		1622	prototypes, but still define all the structs and other symbols. This is
		1623	occasionally useful if you want to provide your own wrapper functions
		1624	around libev functions.</p>
		1625	</dd>
		1626	<dt>EV_MULTIPLICITY</dt>
		1627	<dd>
		1628	<p>If undefined or defined to <code>1</code>, then all event-loop-specific functions
		1629	will have the <code>struct ev_loop *</code> as first argument, and you can create
		1630	additional independent event loops. Otherwise there will be no support
		1631	for multiple event loops and there is no first event loop pointer
		1632	argument. Instead, all functions act on the single default loop.</p>
		1633	</dd>
		1634	<dt>EV_PERIODICS</dt>
		1635	<dd>
		1636	<p>If undefined or defined to be <code>1</code>, then periodic timers are supported,
		1637	otherwise not. This saves a few kb of code.</p>
		1638	</dd>
		1639	<dt>EV_COMMON</dt>
		1640	<dd>
		1641	<p>By default, all watchers have a <code>void *data</code> member. By redefining
		1642	this macro to a something else you can include more and other types of
		1643	members. You have to define it each time you include one of the files,
		1644	though, and it must be identical each time.</p>
		1645	<p>For example, the perl EV module uses something like this:</p>
		1646	<pre> #define EV_COMMON \
		1647	SV self; / contains this struct */ \
		1648	SV cb_sv, fh /* note no trailing ";" */
		1649
		1650	</pre>
		1651	</dd>
		1652	<dt>EV_CB_DECLARE(type)</dt>
		1653	<dt>EV_CB_INVOKE(watcher,revents)</dt>
		1654	<dt>ev_set_cb(ev,cb)</dt>
		1655	<dd>
		1656	<p>Can be used to change the callback member declaration in each watcher,
		1657	and the way callbacks are invoked and set. Must expand to a struct member
		1658	definition and a statement, respectively. See the <cite>ev.v</cite> header file for
		1659	their default definitions. One possible use for overriding these is to
		1660	avoid the ev_loop pointer as first argument in all cases, or to use method
		1661	calls instead of plain function calls in C++.</p>
		1662
		1663	</div>
		1664	<h2 id="EXAMPLES">EXAMPLES</h2>
		1665	<div id="EXAMPLES_CONTENT">
		1666	<p>For a real-world example of a program the includes libev
		1667	verbatim, you can have a look at the EV perl module
		1668	(<a href="http://software.schmorp.de/pkg/EV.html">http://software.schmorp.de/pkg/EV.html</a>). It has the libev files in
		1669	the <cite>libev/</cite> subdirectory and includes them in the <cite>EV/EVAPI.h</cite> (public
		1670	interface) and <cite>EV.xs</cite> (implementation) files. Only the <cite>EV.xs</cite> file
		1671	will be compiled. It is pretty complex because it provides its own header
		1672	file.</p>
		1673	<p>The usage in rxvt-unicode is simpler. It has a <cite>ev_cpp.h</cite> header file
		1674	that everybody includes and which overrides some autoconf choices:</p>
		1675	<pre> #define EV_USE_POLL 0
		1676	#define EV_MULTIPLICITY 0
		1677	#define EV_PERIODICS 0
		1678	#define EV_CONFIG_H <config.h>
		1679
		1680	#include "ev++.h"
		1681
		1682	</pre>
		1683	<p>And a <cite>ev_cpp.C</cite> implementation file that contains libev proper and is compiled:</p>
		1684	<pre> #include "ev_cpp.h"
		1685	#include "ev.c"
		1686
		1687	</pre>
715		1688
716	</div>	1689	</div>
717	<h1 id="AUTHOR">AUTHOR</h1><p><a href="#TOP" class="toplink">Top</a></p>	1690	<h1 id="AUTHOR">AUTHOR</h1><p><a href="#TOP" class="toplink">Top</a></p>
718	<div id="AUTHOR_CONTENT">	1691	<div id="AUTHOR_CONTENT">
719	<p>Marc Lehmann <libev@schmorp.de>.</p>	1692	<p>Marc Lehmann <libev@schmorp.de>.</p>
720		1693
721	</div>	1694	</div>
722	</div></body>	1695	</div></body>
723	</html>	1696	</html>

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Revision 1.41 by root, Sat Nov 24 10:15:16 2007 UTC