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4	<head>	4	<head>
5	<title>libev</title>	5	<title>libev</title>
6	<meta name="description" content="Pod documentation for libev" />	6	<meta name="description" content="Pod documentation for libev" />
7	<meta name="inputfile" content="<standard input>" />	7	<meta name="inputfile" content="<standard input>" />
8	<meta name="outputfile" content="<standard output>" />	8	<meta name="outputfile" content="<standard output>" />
9	<meta name="created" content="Mon Nov 12 20:19:59 2007" />	9	<meta name="created" content="Sat Nov 24 11:15:15 2007" />
10	<meta name="generator" content="Pod::Xhtml 1.57" />	10	<meta name="generator" content="Pod::Xhtml 1.57" />
11	<link rel="stylesheet" href="http://res.tst.eu/pod.css"/></head>	11	<link rel="stylesheet" href="http://res.tst.eu/pod.css"/></head>
12	<body>	12	<body>
13	<div class="pod">	13	<div class="pod">
14	<!-- INDEX START -->	14	<!-- INDEX START -->
…		…
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_REPRESENTATION">TIME REPRESENTATION</a></li>
23	<li><a href="#GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</a></li>	23	<li><a href="#GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</a></li>
24	<li><a href="#FUNCTIONS_CONTROLLING_THE_EVENT_LOOP">FUNCTIONS CONTROLLING THE EVENT LOOP</a></li>	24	<li><a href="#FUNCTIONS_CONTROLLING_THE_EVENT_LOOP">FUNCTIONS CONTROLLING THE EVENT LOOP</a></li>
25	<li><a href="#ANATOMY_OF_A_WATCHER">ANATOMY OF A WATCHER</a>	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>
26	<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>
27	</ul>	28	</ul>
28	</li>	29	</li>
29	<li><a href="#WATCHER_TYPES">WATCHER TYPES</a>	30	<li><a href="#WATCHER_TYPES">WATCHER TYPES</a>
30	<ul><li><a href="#code_ev_io_code_is_this_file_descrip"><code>ev_io</code> - is this file descriptor readable or writable</a></li>	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>
31	<li><a href="#code_ev_timer_code_relative_and_opti"><code>ev_timer</code> - 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>
32	<li><a href="#code_ev_periodic_code_to_cron_or_not"><code>ev_periodic</code> - to cron or not to cron</a></li>	33	<li><a href="#code_ev_periodic_code_to_cron_or_not"><code>ev_periodic</code> - to cron or not to cron</a></li>
33	<li><a href="#code_ev_signal_code_signal_me_when_a"><code>ev_signal</code> - signal me when a signal gets signalled</a></li>	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>
34	<li><a href="#code_ev_child_code_wait_for_pid_stat"><code>ev_child</code> - 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>
35	<li><a href="#code_ev_idle_code_when_you_ve_got_no"><code>ev_idle</code> - when you've got nothing better to do</a></li>	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>
36	<li><a href="#code_ev_prepare_code_and_code_ev_che"><code>ev_prepare</code> and <code>ev_check</code> - customise your event loop</a></li>	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>
37	</ul>	39	</ul>
38	</li>	40	</li>
39	<li><a href="#OTHER_FUNCTIONS">OTHER FUNCTIONS</a></li>	41	<li><a href="#OTHER_FUNCTIONS">OTHER FUNCTIONS</a></li>
40	<li><a href="#LIBEVENT_EMULATION">LIBEVENT EMULATION</a></li>	42	<li><a href="#LIBEVENT_EMULATION">LIBEVENT EMULATION</a></li>
41	<li><a href="#C_SUPPORT">C++ SUPPORT</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>
42	<li><a href="#AUTHOR">AUTHOR</a>	55	<li><a href="#AUTHOR">AUTHOR</a>
43	</li>	56	</li>
44	</ul><hr />	57	</ul><hr />
45	<!-- INDEX END -->	58	<!-- INDEX END -->
46		59
…		…
96	<div id="TIME_REPRESENTATION_CONTENT">	109	<div id="TIME_REPRESENTATION_CONTENT">
97	<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
98	(fractional) number of seconds since the (POSIX) epoch (somewhere near	111	(fractional) number of seconds since the (POSIX) epoch (somewhere near
99	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
100	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
101	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
102		120
103	</div>	121	</div>
104	<h1 id="GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p>	122	<h1 id="GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p>
105	<div id="GLOBAL_FUNCTIONS_CONTENT">	123	<div id="GLOBAL_FUNCTIONS_CONTENT">
106	<p>These functions can be called anytime, even before initialising the	124	<p>These functions can be called anytime, even before initialising the
107	library in any way.</p>	125	library in any way.</p>
108	<dl>	126	<dl>
109	<dt>ev_tstamp ev_time ()</dt>	127	<dt>ev_tstamp ev_time ()</dt>
110	<dd>	128	<dd>
111	<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>
112	</dd>	132	</dd>
113	<dt>int ev_version_major ()</dt>	133	<dt>int ev_version_major ()</dt>
114	<dt>int ev_version_minor ()</dt>	134	<dt>int ev_version_minor ()</dt>
115	<dd>	135	<dd>
116	<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
…		…
120	version of the library your program was compiled against.</p>	140	version of the library your program was compiled against.</p>
121	<p>Usually, it's 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,
122	as this indicates an incompatible change. Minor versions are usually	142	as this indicates an incompatible change. Minor versions are usually
123	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
124	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>
125	</dd>	183	</dd>
126	<dt>ev_set_allocator (void (cb)(void *ptr, long size))</dt>	184	<dt>ev_set_allocator (void (cb)(void *ptr, long size))</dt>
127	<dd>	185	<dd>
128	<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
129	realloc C function, the semantics are identical). It is used to allocate	187	realloc C function, the semantics are identical). It is used to allocate
…		…
131	needs to be allocated, the library might abort or take some potentially	189	needs to be allocated, the library might abort or take some potentially
132	destructive action. The default is your system realloc function.</p>	190	destructive action. The default is your system realloc function.</p>
133	<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,
134	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,
135	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>
136	</dd>	214	</dd>
137	<dt>ev_set_syserr_cb (void (cb)(const char msg));</dt>	215	<dt>ev_set_syserr_cb (void (cb)(const char msg));</dt>
138	<dd>	216	<dd>
139	<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
140	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
141	indicating the system call or subsystem causing the problem. If this	219	indicating the system call or subsystem causing the problem. If this
142	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
143	matter what, when it returns. That is, libev will generally retry the	221	matter what, when it returns. That is, libev will generally retry the
144	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
145	(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>
146	</dd>	236	</dd>
147	</dl>	237	</dl>
148		238
149	</div>	239	</div>
150	<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>
…		…
162	<dt>struct ev_loop *ev_default_loop (unsigned int flags)</dt>	252	<dt>struct ev_loop *ev_default_loop (unsigned int flags)</dt>
163	<dd>	253	<dd>
164	<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
165	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
166	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
167	flags).</p>	257	flags. If that is troubling you, check <code>ev_backend ()</code> afterwards).</p>
168	<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
169	function.</p>	259	function.</p>
170	<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
171	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>
172	<p>It supports the following flags:</p>	262	<p>The following flags are supported:</p>
173	<p>	263	<p>
174	<dl>	264	<dl>
175	<dt><code>EVFLAG_AUTO</code></dt>	265	<dt><code>EVFLAG_AUTO</code></dt>
176	<dd>	266	<dd>
177	<p>The default flags value. Use this if you have no clue (it's the right	267	<p>The default flags value. Use this if you have no clue (it's the right
…		…
184	<code>LIBEV_FLAGS</code>. Otherwise (the default), this environment variable will	274	<code>LIBEV_FLAGS</code>. Otherwise (the default), this environment variable will
185	override the flags completely if it is found in the environment. This is	275	override the flags completely if it is found in the environment. This is
186	useful to try out specific backends to test their performance, or to work	276	useful to try out specific backends to test their performance, or to work
187	around bugs.</p>	277	around bugs.</p>
188	</dd>	278	</dd>
189	<dt><code>EVMETHOD_SELECT</code> (portable select backend)</dt>	279	<dt><code>EVBACKEND_SELECT</code> (value 1, portable select backend)</dt>
190	<dt><code>EVMETHOD_POLL</code> (poll backend, available everywhere except on windows)</dt>	280	<dd>
191	<dt><code>EVMETHOD_EPOLL</code> (linux only)</dt>	281	<p>This is your standard select(2) backend. Not <i>completely</i> standard, as
192	<dt><code>EVMETHOD_KQUEUE</code> (some bsds only)</dt>	282	libev tries to roll its own fd_set with no limits on the number of fds,
193	<dt><code>EVMETHOD_DEVPOLL</code> (solaris 8 only)</dt>	283	but if that fails, expect a fairly low limit on the number of fds when
194	<dt><code>EVMETHOD_PORT</code> (solaris 10 only)</dt>	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>
195	<dd>	286	</dd>
196	<p>If one or more of these are ored into the flags value, then only these	287	<dt><code>EVBACKEND_POLL</code> (value 2, poll backend, available everywhere except on windows)</dt>
197	backends will be tried (in the reverse order as given here). If one are	288	<dd>
198	specified, any backend will do.</p>	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>
199	</dd>	340	</dd>
200	</dl>	341	</dl>
201	</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>
202	</dd>	363	</dd>
203	<dt>struct ev_loop *ev_loop_new (unsigned int flags)</dt>	364	<dt>struct ev_loop *ev_loop_new (unsigned int flags)</dt>
204	<dd>	365	<dd>
205	<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
206	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
207	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
208	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>
209	</dd>	376	</dd>
210	<dt>ev_default_destroy ()</dt>	377	<dt>ev_default_destroy ()</dt>
211	<dd>	378	<dd>
212	<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
213	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
214	any way whatsoever, although you cannot 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>
215	</dd>	386	</dd>
216	<dt>ev_loop_destroy (loop)</dt>	387	<dt>ev_loop_destroy (loop)</dt>
217	<dd>	388	<dd>
218	<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
219	earlier call to <code>ev_loop_new</code>.</p>	390	earlier call to <code>ev_loop_new</code>.</p>
…		…
222	<dd>	393	<dd>
223	<p>This function reinitialises the kernel state for backends that have	394	<p>This function reinitialises the kernel state for backends that have
224	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
225	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
226	again makes little sense).</p>	397	again makes little sense).</p>
227	<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
228	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
229	have to call it.</p>	400	fork+exec, you don't have to call it.</p>
230	<p>The function itself is quite fast and it's usually not a problem to call	401	<p>The function itself is quite fast and it's usually not a problem to call
231	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
232	quite nicely into a call to <code>pthread_atfork</code>:</p>	403	quite nicely into a call to <code>pthread_atfork</code>:</p>
233	<pre> pthread_atfork (0, 0, ev_default_fork);	404	<pre> pthread_atfork (0, 0, ev_default_fork);
234		405
235	</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>
236	</dd>	410	</dd>
237	<dt>ev_loop_fork (loop)</dt>	411	<dt>ev_loop_fork (loop)</dt>
238	<dd>	412	<dd>
239	<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
240	<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
241	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>
242	</dd>	416	</dd>
243	<dt>unsigned int ev_method (loop)</dt>	417	<dt>unsigned int ev_backend (loop)</dt>
244	<dd>	418	<dd>
245	<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
246	use.</p>	420	use.</p>
247	</dd>	421	</dd>
248	<dt>ev_tstamp ev_now (loop)</dt>	422	<dt>ev_tstamp ev_now (loop)</dt>
249	<dd>	423	<dd>
250	<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
251	got events and started processing them. This timestamp does not change	425	received events and started processing them. This timestamp does not
252	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
253	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
254	occuring (or more correctly, the mainloop finding out about it).</p>	428	event occuring (or more correctly, libev finding out about it).</p>
255	</dd>	429	</dd>
256	<dt>ev_loop (loop, int flags)</dt>	430	<dt>ev_loop (loop, int flags)</dt>
257	<dd>	431	<dd>
258	<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
259	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
260	events.</p>	434	events.</p>
261	<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
262	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>
263	<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
264	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
265	case there are no events and will return after one iteration of the loop.</p>	444	case there are no events and will return after one iteration of the loop.</p>
266	<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
267	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
268	your process until at least one new event arrives, and will return after	447	your process until at least one new event arrives, and will return after
269	one iteration of the loop.</p>	448	one iteration of the loop. This is useful if you are waiting for some
270	<p>This flags value could be used to implement alternative looping	449	external event in conjunction with something not expressible using other
271	constructs, but the <code>prepare</code> and <code>check</code> watchers provide a better and	450	libev watchers. However, a pair of <code>ev_prepare</code>/<code>ev_check</code> watchers is
272	more generic mechanism.</p>	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>
273	</dd>	481	</dd>
274	<dt>ev_unloop (loop, how)</dt>	482	<dt>ev_unloop (loop, how)</dt>
275	<dd>	483	<dd>
276	<p>Can be used to make a call to <code>ev_loop</code> return early (but only after it	484	<p>Can be used to make a call to <code>ev_loop</code> return early (but only after it
277	has processed all outstanding events). The <code>how</code> argument must be either	485	has processed all outstanding events). The <code>how</code> argument must be either
278	<code>EVUNLOOP_ONCE</code>, which will make the innermost <code>ev_loop</code> call return, or	486	<code>EVUNLOOP_ONE</code>, which will make the innermost <code>ev_loop</code> call return, or
279	<code>EVUNLOOP_ALL</code>, which will make all nested <code>ev_loop</code> calls return.</p>	487	<code>EVUNLOOP_ALL</code>, which will make all nested <code>ev_loop</code> calls return.</p>
280	</dd>	488	</dd>
281	<dt>ev_ref (loop)</dt>	489	<dt>ev_ref (loop)</dt>
282	<dt>ev_unref (loop)</dt>	490	<dt>ev_unref (loop)</dt>
283	<dd>	491	<dd>
…		…
289	example, libev itself uses this for its internal signal pipe: It is not	497	example, libev itself uses this for its internal signal pipe: It is not
290	visible to the libev user and should not keep <code>ev_loop</code> from exiting if	498	visible to the libev user and should not keep <code>ev_loop</code> from exiting if
291	no event watchers registered by it are active. It is also an excellent	499	no event watchers registered by it are active. It is also an excellent
292	way to do this for generic recurring timers or from within third-party	500	way to do this for generic recurring timers or from within third-party
293	libraries. Just remember to <i>unref after start</i> and <i>ref before stop</i>.</p>	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>
294	</dd>	515	</dd>
295	</dl>	516	</dl>
296		517
297	</div>	518	</div>
298	<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>
…		…
330	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
331	*)</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
332	corresponding stop function (<code>ev_<type>_stop (loop, watcher *)</code>.</p>	553	corresponding stop function (<code>ev_<type>_stop (loop, watcher *)</code>.</p>
333	<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
334	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
335	reinitialise it or call its set method.</p>	556	reinitialise it or call its <code>set</code> macro.</p>
336	<p>You can check whether an event is active by calling the <code>ev_is_active
337	(watcher *)</code> macro. To see whether an event is outstanding (but the
338	callback for it has not been called yet) you can use the <code>ev_is_pending
339	(watcher *)</code> macro.</p>
340	<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
341	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
342	third argument.</p>	559	third argument.</p>
343	<p>The received events usually include a single bit per event type received	560	<p>The received events usually include a single bit per event type received
344	(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
…		…
393	your callbacks is well-written it can just attempt the operation and cope	610	your callbacks is well-written it can just attempt the operation and cope
394	with the error from read() or write(). This will not work in multithreaded	611	with the error from read() or write(). This will not work in multithreaded
395	programs, though, so beware.</p>	612	programs, though, so beware.</p>
396	</dd>	613	</dd>
397	</dl>	614	</dl>
		615
		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
398		693
399	</div>	694	</div>
400	<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>
401	<div id="ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH-2">	696	<div id="ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH-2">
402	<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
…		…
433	</div>	728	</div>
434	<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>
435	<div id="WATCHER_TYPES_CONTENT">	730	<div id="WATCHER_TYPES_CONTENT">
436	<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
437	information given in the last section.</p>	732	information given in the last section.</p>
		733
		734
		735
		736
438		737
439	</div>	738	</div>
440	<h2 id="code_ev_io_code_is_this_file_descrip"><code>ev_io</code> - is this 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>
441	<div id="code_ev_io_code_is_this_file_descrip-2">	740	<div id="code_ev_io_code_is_this_file_descrip-2">
442	<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
…		…
452	(the linux epoll backend is a notable example) cannot handle dup'ed file	751	(the linux epoll backend is a notable example) cannot handle dup'ed file
453	descriptors correctly if you register interest in two or more fds pointing	752	descriptors correctly if you register interest in two or more fds pointing
454	to the same underlying file/socket etc. description (that is, they share	753	to the same underlying file/socket etc. description (that is, they share
455	the same underlying "file open").</p>	754	the same underlying "file open").</p>
456	<p>If you must do this, then force the use of a known-to-be-good backend	755	<p>If you must do this, then force the use of a known-to-be-good backend
457	(at the time of this writing, this includes only EVMETHOD_SELECT and	756	(at the time of this writing, this includes only <code>EVBACKEND_SELECT</code> and
458	EVMETHOD_POLL).</p>	757	<code>EVBACKEND_POLL</code>).</p>
459	<dl>	758	<dl>
460	<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>
461	<dt>ev_io_set (ev_io *, int fd, int events)</dt>	760	<dt>ev_io_set (ev_io *, int fd, int events)</dt>
462	<dd>	761	<dd>
463	<p>Configures an <code>ev_io</code> 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
464	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 \|
465	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>
466	</dd>	775	</dd>
467	</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	}
		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>
468		798
469	</div>	799	</div>
470	<h2 id="code_ev_timer_code_relative_and_opti"><code>ev_timer</code> - 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>
471	<div id="code_ev_timer_code_relative_and_opti-2">	801	<div id="code_ev_timer_code_relative_and_opti-2">
472	<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
473	given time, and optionally repeating in regular intervals after that.</p>	803	given time, and optionally repeating in regular intervals after that.</p>
474	<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
475	times out after an hour and you reset your system clock to last years	805	times out after an hour and you reset your system clock to last years
476	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
477	detecting time jumps is hard, and soem inaccuracies are unavoidable (the	807	detecting time jumps is hard, and some inaccuracies are unavoidable (the
478	monotonic clock option helps a lot here).</p>	808	monotonic clock option helps a lot here).</p>
479	<p>The relative timeouts are calculated relative to the <code>ev_now ()</code>	809	<p>The relative timeouts are calculated relative to the <code>ev_now ()</code>
480	time. This is usually the right thing as this timestamp refers to the time	810	time. This is usually the right thing as this timestamp refers to the time
481	of the event triggering whatever timeout you are modifying/starting. If	811	of the event triggering whatever timeout you are modifying/starting. If
482	you suspect event processing to be delayed and you need to base the timeout	812	you suspect event processing to be delayed and you <i>need</i> to base the timeout
483	on the current time, use something like this to adjust for this:</p>	813	on the current time, use something like this to adjust for this:</p>
484	<pre> ev_timer_set (&timer, after + ev_now () - ev_time (), 0.);	814	<pre> ev_timer_set (&timer, after + ev_now () - ev_time (), 0.);
485		815
486	</pre>	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>
487	<dl>	820	<dl>
488	<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>
489	<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>
490	<dd>	823	<dd>
491	<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
…		…
513	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
514	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
515	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>
516	</dd>	849	</dd>
517	</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	}
		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>
518		884
519	</div>	885	</div>
520	<h2 id="code_ev_periodic_code_to_cron_or_not"><code>ev_periodic</code> - to cron or not to cron</h2>	886	<h2 id="code_ev_periodic_code_to_cron_or_not"><code>ev_periodic</code> - to cron or not to cron</h2>
521	<div id="code_ev_periodic_code_to_cron_or_not-2">	887	<div id="code_ev_periodic_code_to_cron_or_not-2">
522	<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
523	(and unfortunately a bit complex).</p>	889	(and unfortunately a bit complex).</p>
524	<p>Unlike <code>ev_timer</code>'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)
525	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
526	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
527	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 ()
528	+ 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
529	take a year to trigger the event (unlike an <code>ev_timer</code>, which would trigger	895	take a year to trigger the event (unlike an <code>ev_timer</code>, which would trigger
530	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
531	again).</p>	897	again).</p>
532	<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
533	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>
534	<dl>	903	<dl>
535	<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>
536	<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>
537	<dd>	906	<dd>
538	<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
539	operation, and we will explain them from simplest to complex:</p>	908	operation, and we will explain them from simplest to complex:</p>
540
541
542
543
544	<p>	909	<p>
545	<dl>	910	<dl>
546	<dt>* absolute timer (interval = reschedule_cb = 0)</dt>	911	<dt>* absolute timer (interval = reschedule_cb = 0)</dt>
547	<dd>	912	<dd>
548	<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
…		…
607	when you changed some parameters or the reschedule callback would return	972	when you changed some parameters or the reschedule callback would return
608	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
609	program when the crontabs have changed).</p>	974	program when the crontabs have changed).</p>
610	</dd>	975	</dd>
611	</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	}
		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>
612		1013
613	</div>	1014	</div>
614	<h2 id="code_ev_signal_code_signal_me_when_a"><code>ev_signal</code> - 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>
615	<div id="code_ev_signal_code_signal_me_when_a-2">	1016	<div id="code_ev_signal_code_signal_me_when_a-2">
616	<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
…		…
630	<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
631	of the <code>SIGxxx</code> constants).</p>	1032	of the <code>SIGxxx</code> constants).</p>
632	</dd>	1033	</dd>
633	</dl>	1034	</dl>
634		1035
		1036
		1037
		1038
		1039
635	</div>	1040	</div>
636	<h2 id="code_ev_child_code_wait_for_pid_stat"><code>ev_child</code> - 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>
637	<div id="code_ev_child_code_wait_for_pid_stat-2">	1042	<div id="code_ev_child_code_wait_for_pid_stat-2">
638	<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
639	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>
…		…
647	the status word (use the macros from <code>sys/wait.h</code> and see your systems	1052	the status word (use the macros from <code>sys/wait.h</code> and see your systems
648	<code>waitpid</code> documentation). The <code>rpid</code> member contains the pid of the	1053	<code>waitpid</code> documentation). The <code>rpid</code> member contains the pid of the
649	process causing the status change.</p>	1054	process causing the status change.</p>
650	</dd>	1055	</dd>
651	</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	}
		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>
652		1072
653	</div>	1073	</div>
654	<h2 id="code_ev_idle_code_when_you_ve_got_no"><code>ev_idle</code> - 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>
655	<div id="code_ev_idle_code_when_you_ve_got_no-2">	1075	<div id="code_ev_idle_code_when_you_ve_got_no-2">
656	<p>Idle watchers trigger events when there are no other events are pending	1076	<p>Idle watchers trigger events when there are no other events are pending
…		…
672	<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
673	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,
674	believe me.</p>	1094	believe me.</p>
675	</dd>	1095	</dd>
676	</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	}
		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>
677		1115
678	</div>	1116	</div>
679	<h2 id="code_ev_prepare_code_and_code_ev_che"><code>ev_prepare</code> and <code>ev_check</code> - customise your 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>
680	<div id="code_ev_prepare_code_and_code_ev_che-2">	1118	<div id="code_ev_prepare_code_and_code_ev_che-2">
681	<p>Prepare and check watchers are usually (but not always) used in tandem:	1119	<p>Prepare and check watchers are usually (but not always) used in tandem:
682	prepare watchers get invoked before the process blocks and check watchers	1120	prepare watchers get invoked before the process blocks and check watchers
683	afterwards.</p>	1121	afterwards.</p>
684	<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
685	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
686	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>
687	<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
688	to be watched by the other library, registering <code>ev_io</code> watchers for	1127	to be watched by the other library, registering <code>ev_io</code> watchers for
689	them and starting an <code>ev_timer</code> watcher for any timeouts (many libraries	1128	them and starting an <code>ev_timer</code> watcher for any timeouts (many libraries
690	provide just this functionality). Then, in the check watcher you check for	1129	provide just this functionality). Then, in the check watcher you check for
691	any events that occured (by checking the pending status of all watchers	1130	any events that occured (by checking the pending status of all watchers
…		…
707	<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
708	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>
709	macros, but using them is utterly, utterly and completely pointless.</p>	1148	macros, but using them is utterly, utterly and completely pointless.</p>
710	</dd>	1149	</dd>
711	</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
712		1241
713	</div>	1242	</div>
714	<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>
715	<div id="OTHER_FUNCTIONS_CONTENT">	1244	<div id="OTHER_FUNCTIONS_CONTENT">
716	<p>There are some other functions of possible interest. Described. Here. Now.</p>	1245	<p>There are some other functions of possible interest. Described. Here. Now.</p>
…		…
743		1272
744	ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);	1273	ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);
745		1274
746	</pre>	1275	</pre>
747	</dd>	1276	</dd>
748	<dt>ev_feed_event (loop, watcher, int events)</dt>	1277	<dt>ev_feed_event (ev_loop , watcher , int revents)</dt>
749	<dd>	1278	<dd>
750	<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
751	had 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
752	initialised but not necessarily started event watcher).</p>	1281	initialised but not necessarily started event watcher).</p>
753	</dd>	1282	</dd>
754	<dt>ev_feed_fd_event (loop, int fd, int revents)</dt>	1283	<dt>ev_feed_fd_event (ev_loop *, int fd, int revents)</dt>
755	<dd>	1284	<dd>
756	<p>Feed an event on the given fd, as if a file descriptor backend detected	1285	<p>Feed an event on the given fd, as if a file descriptor backend detected
757	the given events it.</p>	1286	the given events it.</p>
758	</dd>	1287	</dd>
759	<dt>ev_feed_signal_event (loop, int signum)</dt>	1288	<dt>ev_feed_signal_event (ev_loop *loop, int signum)</dt>
760	<dd>	1289	<dd>
761	<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>
762	</dd>	1292	</dd>
763	</dl>	1293	</dl>
		1294
		1295
		1296
		1297
764		1298
765	</div>	1299	</div>
766	<h1 id="LIBEVENT_EMULATION">LIBEVENT EMULATION</h1><p><a href="#TOP" class="toplink">Top</a></p>	1300	<h1 id="LIBEVENT_EMULATION">LIBEVENT EMULATION</h1><p><a href="#TOP" class="toplink">Top</a></p>
767	<div id="LIBEVENT_EMULATION_CONTENT">	1301	<div id="LIBEVENT_EMULATION_CONTENT">
768	<p>Libev offers a compatibility emulation layer for libevent. It cannot	1302	<p>Libev offers a compatibility emulation layer for libevent. It cannot
…		…
783	</dl>	1317	</dl>
784		1318
785	</div>	1319	</div>
786	<h1 id="C_SUPPORT">C++ SUPPORT</h1><p><a href="#TOP" class="toplink">Top</a></p>	1320	<h1 id="C_SUPPORT">C++ SUPPORT</h1><p><a href="#TOP" class="toplink">Top</a></p>
787	<div id="C_SUPPORT_CONTENT">	1321	<div id="C_SUPPORT_CONTENT">
788	<p>TBD.</p>	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>
789		1688
790	</div>	1689	</div>
791	<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>
792	<div id="AUTHOR_CONTENT">	1691	<div id="AUTHOR_CONTENT">
793	<p>Marc Lehmann <libev@schmorp.de>.</p>	1692	<p>Marc Lehmann <libev@schmorp.de>.</p>
794		1693
795	</div>	1694	</div>
796	</div></body>	1695	</div></body>
797	</html>	1696	</html>

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