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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="Thu Nov 22 13:26:17 2007" />	9	<meta name="created" content="Sat Nov 24 17:57:37 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="#GENERIC_WATCHER_FUNCTIONS">GENERIC WATCHER FUNCTIONS</a></li>
26	<ul><li><a href="#ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH">ASSOCIATING CUSTOM DATA WITH A WATCHER</a></li>	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 repeating timeouts</a></li>
32	<li><a href="#code_ev_periodic_code_to_cron_or_not"><code>ev_periodic</code> - to cron or not to cron</a></li>	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_watch_out_for_pro"><code>ev_child</code> - watch out for process 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
…		…
122	version of the library your program was compiled against.</p>	140	version of the library your program was compiled against.</p>
123	<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,
124	as this indicates an incompatible change. Minor versions are usually	142	as this indicates an incompatible change. Minor versions are usually
125	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
126	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>
127	</dd>	183	</dd>
128	<dt>ev_set_allocator (void (cb)(void *ptr, long size))</dt>	184	<dt>ev_set_allocator (void (cb)(void *ptr, long size))</dt>
129	<dd>	185	<dd>
130	<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
131	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
…		…
133	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
134	destructive action. The default is your system realloc function.</p>	190	destructive action. The default is your system realloc function.</p>
135	<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,
136	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,
137	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>
138	</dd>	214	</dd>
139	<dt>ev_set_syserr_cb (void (cb)(const char msg));</dt>	215	<dt>ev_set_syserr_cb (void (cb)(const char msg));</dt>
140	<dd>	216	<dd>
141	<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
142	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
143	indicating the system call or subsystem causing the problem. If this	219	indicating the system call or subsystem causing the problem. If this
144	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
145	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
146	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
147	(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>
148	</dd>	236	</dd>
149	</dl>	237	</dl>
150		238
151	</div>	239	</div>
152	<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>
…		…
164	<dt>struct ev_loop *ev_default_loop (unsigned int flags)</dt>	252	<dt>struct ev_loop *ev_default_loop (unsigned int flags)</dt>
165	<dd>	253	<dd>
166	<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
167	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
168	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
169	flags).</p>	257	flags. If that is troubling you, check <code>ev_backend ()</code> afterwards).</p>
170	<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
171	function.</p>	259	function.</p>
172	<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
173	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>
174	<p>It supports the following flags:</p>	262	<p>The following flags are supported:</p>
175	<p>	263	<p>
176	<dl>	264	<dl>
177	<dt><code>EVFLAG_AUTO</code></dt>	265	<dt><code>EVFLAG_AUTO</code></dt>
178	<dd>	266	<dd>
179	<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
…		…
186	<code>LIBEV_FLAGS</code>. Otherwise (the default), this environment variable will	274	<code>LIBEV_FLAGS</code>. Otherwise (the default), this environment variable will
187	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
188	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
189	around bugs.</p>	277	around bugs.</p>
190	</dd>	278	</dd>
191	<dt><code>EVMETHOD_SELECT</code> (value 1, portable select backend)</dt>	279	<dt><code>EVBACKEND_SELECT</code> (value 1, portable select backend)</dt>
192	<dd>	280	<dd>
193	<p>This is your standard select(2) backend. Not <i>completely</i> standard, as	281	<p>This is your standard select(2) backend. Not <i>completely</i> standard, as
194	libev tries to roll its own fd_set with no limits on the number of fds,	282	libev tries to roll its own fd_set with no limits on the number of fds,
195	but if that fails, expect a fairly low limit on the number of fds when	283	but if that fails, expect a fairly low limit on the number of fds when
196	using this backend. It doesn't scale too well (O(highest_fd)), but its usually	284	using this backend. It doesn't scale too well (O(highest_fd)), but its usually
197	the fastest backend for a low number of fds.</p>	285	the fastest backend for a low number of fds.</p>
198	</dd>	286	</dd>
199	<dt><code>EVMETHOD_POLL</code> (value 2, poll backend, available everywhere except on windows)</dt>	287	<dt><code>EVBACKEND_POLL</code> (value 2, poll backend, available everywhere except on windows)</dt>
200	<dd>	288	<dd>
201	<p>And this is your standard poll(2) backend. It's more complicated than	289	<p>And this is your standard poll(2) backend. It's more complicated than
202	select, but handles sparse fds better and has no artificial limit on the	290	select, but handles sparse fds better and has no artificial limit on the
203	number of fds you can use (except it will slow down considerably with a	291	number of fds you can use (except it will slow down considerably with a
204	lot of inactive fds). It scales similarly to select, i.e. O(total_fds).</p>	292	lot of inactive fds). It scales similarly to select, i.e. O(total_fds).</p>
205	</dd>	293	</dd>
206	<dt><code>EVMETHOD_EPOLL</code> (value 4, Linux)</dt>	294	<dt><code>EVBACKEND_EPOLL</code> (value 4, Linux)</dt>
207	<dd>	295	<dd>
208	<p>For few fds, this backend is a bit little slower than poll and select,	296	<p>For few fds, this backend is a bit little slower than poll and select,
209	but it scales phenomenally better. While poll and select usually scale like	297	but it scales phenomenally better. While poll and select usually scale like
210	O(total_fds) where n is the total number of fds (or the highest fd), epoll scales	298	O(total_fds) where n is the total number of fds (or the highest fd), epoll scales
211	either O(1) or O(active_fds).</p>	299	either O(1) or O(active_fds).</p>
212	<p>While stopping and starting an I/O watcher in the same iteration will	300	<p>While stopping and starting an I/O watcher in the same iteration will
213	result in some caching, there is still a syscall per such incident	301	result in some caching, there is still a syscall per such incident
214	(because the fd could point to a different file description now), so its	302	(because the fd could point to a different file description now), so its
215	best to avoid that. Also, dup()ed file descriptors might not work very	303	best to avoid that. Also, dup()ed file descriptors might not work very
216	well if you register events for both fds.</p>	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>
217	</dd>	308	</dd>
218	<dt><code>EVMETHOD_KQUEUE</code> (value 8, most BSD clones)</dt>	309	<dt><code>EVBACKEND_KQUEUE</code> (value 8, most BSD clones)</dt>
219	<dd>	310	<dd>
220	<p>Kqueue deserves special mention, as at the time of this writing, it	311	<p>Kqueue deserves special mention, as at the time of this writing, it
221	was broken on all BSDs except NetBSD (usually it doesn't work with	312	was broken on all BSDs except NetBSD (usually it doesn't work with
222	anything but sockets and pipes, except on Darwin, where of course its	313	anything but sockets and pipes, except on Darwin, where of course its
223	completely useless). For this reason its not being "autodetected" unless	314	completely useless). For this reason its not being "autodetected"
224	you explicitly specify the flags (i.e. you don't use EVFLAG_AUTO).</p>	315	unless you explicitly specify it explicitly in the flags (i.e. using
		316	<code>EVBACKEND_KQUEUE</code>).</p>
225	<p>It scales in the same way as the epoll backend, but the interface to the	317	<p>It scales in the same way as the epoll backend, but the interface to the
226	kernel is more efficient (which says nothing about its actual speed, of	318	kernel is more efficient (which says nothing about its actual speed, of
227	course). While starting and stopping an I/O watcher does not cause an	319	course). While starting and stopping an I/O watcher does not cause an
228	extra syscall as with epoll, it still adds up to four event changes per	320	extra syscall as with epoll, it still adds up to four event changes per
229	incident, so its best to avoid that.</p>	321	incident, so its best to avoid that.</p>
230	</dd>	322	</dd>
231	<dt><code>EVMETHOD_DEVPOLL</code> (value 16, Solaris 8)</dt>	323	<dt><code>EVBACKEND_DEVPOLL</code> (value 16, Solaris 8)</dt>
232	<dd>	324	<dd>
233	<p>This is not implemented yet (and might never be).</p>	325	<p>This is not implemented yet (and might never be).</p>
234	</dd>	326	</dd>
235	<dt><code>EVMETHOD_PORT</code> (value 32, Solaris 10)</dt>	327	<dt><code>EVBACKEND_PORT</code> (value 32, Solaris 10)</dt>
236	<dd>	328	<dd>
237	<p>This uses the Solaris 10 port mechanism. As with everything on Solaris,	329	<p>This uses the Solaris 10 port mechanism. As with everything on Solaris,
238	it's really slow, but it still scales very well (O(active_fds)).</p>	330	it's really slow, but it still scales very well (O(active_fds)).</p>
239	</dd>	331	<p>Please note that solaris ports can result in a lot of spurious
240	<dt><code>EVMETHOD_ALL</code></dt>	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>
241	<dd>	334	</dd>
		335	<dt><code>EVBACKEND_ALL</code></dt>
		336	<dd>
242	<p>Try all backends (even potentially broken ones). Since this is a mask, you	337	<p>Try all backends (even potentially broken ones that wouldn't be tried
243	can do stuff like <code>EVMETHOD_ALL & ~EVMETHOD_KQUEUE</code>.</p>	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>
244	</dd>	340	</dd>
245	</dl>	341	</dl>
246	</p>	342	</p>
247	<p>If one or more of these are ored into the flags value, then only these	343	<p>If one or more of these are ored into the flags value, then only these
248	backends will be tried (in the reverse order as given here). If none are	344	backends will be tried (in the reverse order as given here). If none are
249	specified, most compiled-in backend will be tried, usually in reverse	345	specified, most compiled-in backend will be tried, usually in reverse
250	order of their flag values :)</p>	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>
251	</dd>	363	</dd>
252	<dt>struct ev_loop *ev_loop_new (unsigned int flags)</dt>	364	<dt>struct ev_loop *ev_loop_new (unsigned int flags)</dt>
253	<dd>	365	<dd>
254	<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
255	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
256	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
257	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>
258	</dd>	376	</dd>
259	<dt>ev_default_destroy ()</dt>	377	<dt>ev_default_destroy ()</dt>
260	<dd>	378	<dd>
261	<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
262	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
263	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>
264	</dd>	386	</dd>
265	<dt>ev_loop_destroy (loop)</dt>	387	<dt>ev_loop_destroy (loop)</dt>
266	<dd>	388	<dd>
267	<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
268	earlier call to <code>ev_loop_new</code>.</p>	390	earlier call to <code>ev_loop_new</code>.</p>
…		…
271	<dd>	393	<dd>
272	<p>This function reinitialises the kernel state for backends that have	394	<p>This function reinitialises the kernel state for backends that have
273	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
274	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
275	again makes little sense).</p>	397	again makes little sense).</p>
276	<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
277	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
278	have to call it.</p>	400	fork+exec, you don't have to call it.</p>
279	<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
280	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
281	quite nicely into a call to <code>pthread_atfork</code>:</p>	403	quite nicely into a call to <code>pthread_atfork</code>:</p>
282	<pre> pthread_atfork (0, 0, ev_default_fork);	404	<pre> pthread_atfork (0, 0, ev_default_fork);
283		405
284	</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>
285	</dd>	410	</dd>
286	<dt>ev_loop_fork (loop)</dt>	411	<dt>ev_loop_fork (loop)</dt>
287	<dd>	412	<dd>
288	<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
289	<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
290	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>
291	</dd>	416	</dd>
292	<dt>unsigned int ev_method (loop)</dt>	417	<dt>unsigned int ev_backend (loop)</dt>
293	<dd>	418	<dd>
294	<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
295	use.</p>	420	use.</p>
296	</dd>	421	</dd>
297	<dt>ev_tstamp ev_now (loop)</dt>	422	<dt>ev_tstamp ev_now (loop)</dt>
298	<dd>	423	<dd>
299	<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
300	got events and started processing them. This timestamp does not change	425	received events and started processing them. This timestamp does not
301	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
302	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
303	occuring (or more correctly, the mainloop finding out about it).</p>	428	event occuring (or more correctly, libev finding out about it).</p>
304	</dd>	429	</dd>
305	<dt>ev_loop (loop, int flags)</dt>	430	<dt>ev_loop (loop, int flags)</dt>
306	<dd>	431	<dd>
307	<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
308	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
309	events.</p>	434	events.</p>
310	<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
311	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>
312	<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
313	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
314	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>
315	<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
316	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
317	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
318	one iteration of the loop.</p>	448	one iteration of the loop. This is useful if you are waiting for some
319	<p>This flags value could be used to implement alternative looping	449	external event in conjunction with something not expressible using other
320	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
321	more generic mechanism.</p>	451	usually a better approach for this kind of thing.</p>
322	<p>Here are the gory details of what ev_loop does:</p>	452	<p>Here are the gory details of what <code>ev_loop</code> does:</p>
323	<pre> 1. If there are no active watchers (reference count is zero), return.	453	<pre> * If there are no active watchers (reference count is zero), return.
324	2. Queue and immediately call all prepare watchers.	454	- Queue prepare watchers and then call all outstanding watchers.
325	3. If we have been forked, recreate the kernel state.	455	- If we have been forked, recreate the kernel state.
326	4. Update the kernel state with all outstanding changes.	456	- Update the kernel state with all outstanding changes.
327	5. Update the "event loop time".	457	- Update the "event loop time".
328	6. Calculate for how long to block.	458	- Calculate for how long to block.
329	7. Block the process, waiting for events.	459	- Block the process, waiting for any events.
		460	- Queue all outstanding I/O (fd) events.
330	8. Update the "event loop time" and do time jump handling.	461	- Update the "event loop time" and do time jump handling.
331	9. Queue all outstanding timers.	462	- Queue all outstanding timers.
332	10. Queue all outstanding periodics.	463	- Queue all outstanding periodics.
333	11. If no events are pending now, queue all idle watchers.	464	- If no events are pending now, queue all idle watchers.
334	12. Queue all check watchers.	465	- Queue all check watchers.
335	13. Call all queued watchers in reverse order (i.e. check watchers first).	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.
336	14. If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK	469	- If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK
337	was used, return, otherwise continue with step #1.	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!
338		479
339	</pre>	480	</pre>
340	</dd>	481	</dd>
341	<dt>ev_unloop (loop, how)</dt>	482	<dt>ev_unloop (loop, how)</dt>
342	<dd>	483	<dd>
…		…
356	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
357	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
358	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
359	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
360	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>
361	</dd>	515	</dd>
362	</dl>	516	</dl>
		517
		518
		519
		520
363		521
364	</div>	522	</div>
365	<h1 id="ANATOMY_OF_A_WATCHER">ANATOMY OF A WATCHER</h1><p><a href="#TOP" class="toplink">Top</a></p>	523	<h1 id="ANATOMY_OF_A_WATCHER">ANATOMY OF A WATCHER</h1><p><a href="#TOP" class="toplink">Top</a></p>
366	<div id="ANATOMY_OF_A_WATCHER_CONTENT">	524	<div id="ANATOMY_OF_A_WATCHER_CONTENT">
367	<p>A watcher is a structure that you create and register to record your	525	<p>A watcher is a structure that you create and register to record your
…		…
397	with a watcher-specific start function (<code>ev_<type>_start (loop, watcher	555	with a watcher-specific start function (<code>ev_<type>_start (loop, watcher
398	*)</code>), and you can stop watching for events at any time by calling the	556	*)</code>), and you can stop watching for events at any time by calling the
399	corresponding stop function (<code>ev_<type>_stop (loop, watcher *)</code>.</p>	557	corresponding stop function (<code>ev_<type>_stop (loop, watcher *)</code>.</p>
400	<p>As long as your watcher is active (has been started but not stopped) you	558	<p>As long as your watcher is active (has been started but not stopped) you
401	must not touch the values stored in it. Most specifically you must never	559	must not touch the values stored in it. Most specifically you must never
402	reinitialise it or call its set method.</p>	560	reinitialise it or call its <code>set</code> macro.</p>
403	<p>You can check whether an event is active by calling the <code>ev_is_active
404	(watcher *)</code> macro. To see whether an event is outstanding (but the
405	callback for it has not been called yet) you can use the <code>ev_is_pending
406	(watcher *)</code> macro.</p>
407	<p>Each and every callback receives the event loop pointer as first, the	561	<p>Each and every callback receives the event loop pointer as first, the
408	registered watcher structure as second, and a bitset of received events as	562	registered watcher structure as second, and a bitset of received events as
409	third argument.</p>	563	third argument.</p>
410	<p>The received events usually include a single bit per event type received	564	<p>The received events usually include a single bit per event type received
411	(you can receive multiple events at the same time). The possible bit masks	565	(you can receive multiple events at the same time). The possible bit masks
…		…
460	your callbacks is well-written it can just attempt the operation and cope	614	your callbacks is well-written it can just attempt the operation and cope
461	with the error from read() or write(). This will not work in multithreaded	615	with the error from read() or write(). This will not work in multithreaded
462	programs, though, so beware.</p>	616	programs, though, so beware.</p>
463	</dd>	617	</dd>
464	</dl>	618	</dl>
		619
		620	</div>
		621	<h2 id="GENERIC_WATCHER_FUNCTIONS">GENERIC WATCHER FUNCTIONS</h2>
		622	<div id="GENERIC_WATCHER_FUNCTIONS_CONTENT">
		623	<p>In the following description, <code>TYPE</code> stands for the watcher type,
		624	e.g. <code>timer</code> for <code>ev_timer</code> watchers and <code>io</code> for <code>ev_io</code> watchers.</p>
		625	<dl>
		626	<dt><code>ev_init</code> (ev_TYPE *watcher, callback)</dt>
		627	<dd>
		628	<p>This macro initialises the generic portion of a watcher. The contents
		629	of the watcher object can be arbitrary (so <code>malloc</code> will do). Only
		630	the generic parts of the watcher are initialised, you <i>need</i> to call
		631	the type-specific <code>ev_TYPE_set</code> macro afterwards to initialise the
		632	type-specific parts. For each type there is also a <code>ev_TYPE_init</code> macro
		633	which rolls both calls into one.</p>
		634	<p>You can reinitialise a watcher at any time as long as it has been stopped
		635	(or never started) and there are no pending events outstanding.</p>
		636	<p>The callback is always of type <code>void ()(ev_loop loop, ev_TYPE *watcher,
		637	int revents)</code>.</p>
		638	</dd>
		639	<dt><code>ev_TYPE_set</code> (ev_TYPE *, [args])</dt>
		640	<dd>
		641	<p>This macro initialises the type-specific parts of a watcher. You need to
		642	call <code>ev_init</code> at least once before you call this macro, but you can
		643	call <code>ev_TYPE_set</code> any number of times. You must not, however, call this
		644	macro on a watcher that is active (it can be pending, however, which is a
		645	difference to the <code>ev_init</code> macro).</p>
		646	<p>Although some watcher types do not have type-specific arguments
		647	(e.g. <code>ev_prepare</code>) you still need to call its <code>set</code> macro.</p>
		648	</dd>
		649	<dt><code>ev_TYPE_init</code> (ev_TYPE *watcher, callback, [args])</dt>
		650	<dd>
		651	<p>This convinience macro rolls both <code>ev_init</code> and <code>ev_TYPE_set</code> macro
		652	calls into a single call. This is the most convinient method to initialise
		653	a watcher. The same limitations apply, of course.</p>
		654	</dd>
		655	<dt><code>ev_TYPE_start</code> (loop , ev_TYPE watcher)</dt>
		656	<dd>
		657	<p>Starts (activates) the given watcher. Only active watchers will receive
		658	events. If the watcher is already active nothing will happen.</p>
		659	</dd>
		660	<dt><code>ev_TYPE_stop</code> (loop , ev_TYPE watcher)</dt>
		661	<dd>
		662	<p>Stops the given watcher again (if active) and clears the pending
		663	status. It is possible that stopped watchers are pending (for example,
		664	non-repeating timers are being stopped when they become pending), but
		665	<code>ev_TYPE_stop</code> ensures that the watcher is neither active nor pending. If
		666	you want to free or reuse the memory used by the watcher it is therefore a
		667	good idea to always call its <code>ev_TYPE_stop</code> function.</p>
		668	</dd>
		669	<dt>bool ev_is_active (ev_TYPE *watcher)</dt>
		670	<dd>
		671	<p>Returns a true value iff the watcher is active (i.e. it has been started
		672	and not yet been stopped). As long as a watcher is active you must not modify
		673	it.</p>
		674	</dd>
		675	<dt>bool ev_is_pending (ev_TYPE *watcher)</dt>
		676	<dd>
		677	<p>Returns a true value iff the watcher is pending, (i.e. it has outstanding
		678	events but its callback has not yet been invoked). As long as a watcher
		679	is pending (but not active) you must not call an init function on it (but
		680	<code>ev_TYPE_set</code> is safe) and you must make sure the watcher is available to
		681	libev (e.g. you cnanot <code>free ()</code> it).</p>
		682	</dd>
		683	<dt>callback = ev_cb (ev_TYPE *watcher)</dt>
		684	<dd>
		685	<p>Returns the callback currently set on the watcher.</p>
		686	</dd>
		687	<dt>ev_cb_set (ev_TYPE *watcher, callback)</dt>
		688	<dd>
		689	<p>Change the callback. You can change the callback at virtually any time
		690	(modulo threads).</p>
		691	</dd>
		692	</dl>
		693
		694
		695
		696
465		697
466	</div>	698	</div>
467	<h2 id="ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH">ASSOCIATING CUSTOM DATA WITH A WATCHER</h2>	699	<h2 id="ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH">ASSOCIATING CUSTOM DATA WITH A WATCHER</h2>
468	<div id="ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH-2">	700	<div id="ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH-2">
469	<p>Each watcher has, by default, a member <code>void *data</code> that you can change	701	<p>Each watcher has, by default, a member <code>void *data</code> that you can change
…		…
501	<h1 id="WATCHER_TYPES">WATCHER TYPES</h1><p><a href="#TOP" class="toplink">Top</a></p>	733	<h1 id="WATCHER_TYPES">WATCHER TYPES</h1><p><a href="#TOP" class="toplink">Top</a></p>
502	<div id="WATCHER_TYPES_CONTENT">	734	<div id="WATCHER_TYPES_CONTENT">
503	<p>This section describes each watcher in detail, but will not repeat	735	<p>This section describes each watcher in detail, but will not repeat
504	information given in the last section.</p>	736	information given in the last section.</p>
505		737
		738
		739
		740
		741
506	</div>	742	</div>
507	<h2 id="code_ev_io_code_is_this_file_descrip"><code>ev_io</code> - is this file descriptor readable or writable</h2>	743	<h2 id="code_ev_io_code_is_this_file_descrip"><code>ev_io</code> - is this file descriptor readable or writable?</h2>
508	<div id="code_ev_io_code_is_this_file_descrip-2">	744	<div id="code_ev_io_code_is_this_file_descrip-2">
509	<p>I/O watchers check whether a file descriptor is readable or writable	745	<p>I/O watchers check whether a file descriptor is readable or writable
510	in each iteration of the event loop (This behaviour is called	746	in each iteration of the event loop, or, more precisely, when reading
511	level-triggering because you keep receiving events as long as the	747	would not block the process and writing would at least be able to write
512	condition persists. Remember you can stop the watcher if you don't want to	748	some data. This behaviour is called level-triggering because you keep
513	act on the event and neither want to receive future events).</p>	749	receiving events as long as the condition persists. Remember you can stop
		750	the watcher if you don't want to act on the event and neither want to
		751	receive future events.</p>
514	<p>In general you can register as many read and/or write event watchers per	752	<p>In general you can register as many read and/or write event watchers per
515	fd as you want (as long as you don't confuse yourself). Setting all file	753	fd as you want (as long as you don't confuse yourself). Setting all file
516	descriptors to non-blocking mode is also usually a good idea (but not	754	descriptors to non-blocking mode is also usually a good idea (but not
517	required if you know what you are doing).</p>	755	required if you know what you are doing).</p>
518	<p>You have to be careful with dup'ed file descriptors, though. Some backends	756	<p>You have to be careful with dup'ed file descriptors, though. Some backends
519	(the linux epoll backend is a notable example) cannot handle dup'ed file	757	(the linux epoll backend is a notable example) cannot handle dup'ed file
520	descriptors correctly if you register interest in two or more fds pointing	758	descriptors correctly if you register interest in two or more fds pointing
521	to the same underlying file/socket etc. description (that is, they share	759	to the same underlying file/socket/etc. description (that is, they share
522	the same underlying "file open").</p>	760	the same underlying "file open").</p>
523	<p>If you must do this, then force the use of a known-to-be-good backend	761	<p>If you must do this, then force the use of a known-to-be-good backend
524	(at the time of this writing, this includes only EVMETHOD_SELECT and	762	(at the time of this writing, this includes only <code>EVBACKEND_SELECT</code> and
525	EVMETHOD_POLL).</p>	763	<code>EVBACKEND_POLL</code>).</p>
		764	<p>Another thing you have to watch out for is that it is quite easy to
		765	receive "spurious" readyness notifications, that is your callback might
		766	be called with <code>EV_READ</code> but a subsequent <code>read</code>(2) will actually block
		767	because there is no data. Not only are some backends known to create a
		768	lot of those (for example solaris ports), it is very easy to get into
		769	this situation even with a relatively standard program structure. Thus
		770	it is best to always use non-blocking I/O: An extra <code>read</code>(2) returning
		771	<code>EAGAIN</code> is far preferable to a program hanging until some data arrives.</p>
		772	<p>If you cannot run the fd in non-blocking mode (for example you should not
		773	play around with an Xlib connection), then you have to seperately re-test
		774	wether a file descriptor is really ready with a known-to-be good interface
		775	such as poll (fortunately in our Xlib example, Xlib already does this on
		776	its own, so its quite safe to use).</p>
526	<dl>	777	<dl>
527	<dt>ev_io_init (ev_io *, callback, int fd, int events)</dt>	778	<dt>ev_io_init (ev_io *, callback, int fd, int events)</dt>
528	<dt>ev_io_set (ev_io *, int fd, int events)</dt>	779	<dt>ev_io_set (ev_io *, int fd, int events)</dt>
529	<dd>	780	<dd>
530	<p>Configures an <code>ev_io</code> watcher. The fd is the file descriptor to rceeive	781	<p>Configures an <code>ev_io</code> watcher. The <code>fd</code> is the file descriptor to
531	events for and events is either <code>EV_READ</code>, <code>EV_WRITE</code> or <code>EV_READ \|	782	rceeive events for and events is either <code>EV_READ</code>, <code>EV_WRITE</code> or
532	EV_WRITE</code> to receive the given events.</p>	783	<code>EV_READ \| EV_WRITE</code> to receive the given events.</p>
533	</dd>	784	</dd>
534	</dl>	785	</dl>
		786	<p>Example: call <code>stdin_readable_cb</code> when STDIN_FILENO has become, well
		787	readable, but only once. Since it is likely line-buffered, you could
		788	attempt to read a whole line in the callback:</p>
		789	<pre> static void
		790	stdin_readable_cb (struct ev_loop loop, struct ev_io w, int revents)
		791	{
		792	ev_io_stop (loop, w);
		793	.. read from stdin here (or from w->fd) and haqndle any I/O errors
		794	}
535		795
		796	...
		797	struct ev_loop *loop = ev_default_init (0);
		798	struct ev_io stdin_readable;
		799	ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);
		800	ev_io_start (loop, &stdin_readable);
		801	ev_loop (loop, 0);
		802
		803
		804
		805
		806	</pre>
		807
536	</div>	808	</div>
537	<h2 id="code_ev_timer_code_relative_and_opti"><code>ev_timer</code> - relative and optionally recurring timeouts</h2>	809	<h2 id="code_ev_timer_code_relative_and_opti"><code>ev_timer</code> - relative and optionally repeating timeouts</h2>
538	<div id="code_ev_timer_code_relative_and_opti-2">	810	<div id="code_ev_timer_code_relative_and_opti-2">
539	<p>Timer watchers are simple relative timers that generate an event after a	811	<p>Timer watchers are simple relative timers that generate an event after a
540	given time, and optionally repeating in regular intervals after that.</p>	812	given time, and optionally repeating in regular intervals after that.</p>
541	<p>The timers are based on real time, that is, if you register an event that	813	<p>The timers are based on real time, that is, if you register an event that
542	times out after an hour and you reset your system clock to last years	814	times out after an hour and you reset your system clock to last years
…		…
583	time you successfully read or write some data. If you go into an idle	855	time you successfully read or write some data. If you go into an idle
584	state where you do not expect data to travel on the socket, you can stop	856	state where you do not expect data to travel on the socket, you can stop
585	the timer, and again will automatically restart it if need be.</p>	857	the timer, and again will automatically restart it if need be.</p>
586	</dd>	858	</dd>
587	</dl>	859	</dl>
		860	<p>Example: create a timer that fires after 60 seconds.</p>
		861	<pre> static void
		862	one_minute_cb (struct ev_loop loop, struct ev_timer w, int revents)
		863	{
		864	.. one minute over, w is actually stopped right here
		865	}
588		866
		867	struct ev_timer mytimer;
		868	ev_timer_init (&mytimer, one_minute_cb, 60., 0.);
		869	ev_timer_start (loop, &mytimer);
		870
		871	</pre>
		872	<p>Example: create a timeout timer that times out after 10 seconds of
		873	inactivity.</p>
		874	<pre> static void
		875	timeout_cb (struct ev_loop loop, struct ev_timer w, int revents)
		876	{
		877	.. ten seconds without any activity
		878	}
		879
		880	struct ev_timer mytimer;
		881	ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */
		882	ev_timer_again (&mytimer); /* start timer */
		883	ev_loop (loop, 0);
		884
		885	// and in some piece of code that gets executed on any "activity":
		886	// reset the timeout to start ticking again at 10 seconds
		887	ev_timer_again (&mytimer);
		888
		889
		890
		891
		892	</pre>
		893
589	</div>	894	</div>
590	<h2 id="code_ev_periodic_code_to_cron_or_not"><code>ev_periodic</code> - to cron or not to cron</h2>	895	<h2 id="code_ev_periodic_code_to_cron_or_not"><code>ev_periodic</code> - to cron or not to cron?</h2>
591	<div id="code_ev_periodic_code_to_cron_or_not-2">	896	<div id="code_ev_periodic_code_to_cron_or_not-2">
592	<p>Periodic watchers are also timers of a kind, but they are very versatile	897	<p>Periodic watchers are also timers of a kind, but they are very versatile
593	(and unfortunately a bit complex).</p>	898	(and unfortunately a bit complex).</p>
594	<p>Unlike <code>ev_timer</code>'s, they are not based on real time (or relative time)	899	<p>Unlike <code>ev_timer</code>'s, they are not based on real time (or relative time)
595	but on wallclock time (absolute time). You can tell a periodic watcher	900	but on wallclock time (absolute time). You can tell a periodic watcher
596	to trigger "at" some specific point in time. For example, if you tell a	901	to trigger "at" some specific point in time. For example, if you tell a
597	periodic watcher to trigger in 10 seconds (by specifiying e.g. c<ev_now ()	902	periodic watcher to trigger in 10 seconds (by specifiying e.g. <code>ev_now ()
598	+ 10.>) and then reset your system clock to the last year, then it will	903	+ 10.</code>) and then reset your system clock to the last year, then it will
599	take a year to trigger the event (unlike an <code>ev_timer</code>, which would trigger	904	take a year to trigger the event (unlike an <code>ev_timer</code>, which would trigger
600	roughly 10 seconds later and of course not if you reset your system time	905	roughly 10 seconds later and of course not if you reset your system time
601	again).</p>	906	again).</p>
602	<p>They can also be used to implement vastly more complex timers, such as	907	<p>They can also be used to implement vastly more complex timers, such as
603	triggering an event on eahc midnight, local time.</p>	908	triggering an event on eahc midnight, local time.</p>
…		…
676	when you changed some parameters or the reschedule callback would return	981	when you changed some parameters or the reschedule callback would return
677	a different time than the last time it was called (e.g. in a crond like	982	a different time than the last time it was called (e.g. in a crond like
678	program when the crontabs have changed).</p>	983	program when the crontabs have changed).</p>
679	</dd>	984	</dd>
680	</dl>	985	</dl>
		986	<p>Example: call a callback every hour, or, more precisely, whenever the
		987	system clock is divisible by 3600. The callback invocation times have
		988	potentially a lot of jittering, but good long-term stability.</p>
		989	<pre> static void
		990	clock_cb (struct ev_loop loop, struct ev_io w, int revents)
		991	{
		992	... its now a full hour (UTC, or TAI or whatever your clock follows)
		993	}
681		994
		995	struct ev_periodic hourly_tick;
		996	ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);
		997	ev_periodic_start (loop, &hourly_tick);
		998
		999	</pre>
		1000	<p>Example: the same as above, but use a reschedule callback to do it:</p>
		1001	<pre> #include <math.h>
		1002
		1003	static ev_tstamp
		1004	my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)
		1005	{
		1006	return fmod (now, 3600.) + 3600.;
		1007	}
		1008
		1009	ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);
		1010
		1011	</pre>
		1012	<p>Example: call a callback every hour, starting now:</p>
		1013	<pre> struct ev_periodic hourly_tick;
		1014	ev_periodic_init (&hourly_tick, clock_cb,
		1015	fmod (ev_now (loop), 3600.), 3600., 0);
		1016	ev_periodic_start (loop, &hourly_tick);
		1017
		1018
		1019
		1020
		1021	</pre>
		1022
682	</div>	1023	</div>
683	<h2 id="code_ev_signal_code_signal_me_when_a"><code>ev_signal</code> - signal me when a signal gets signalled</h2>	1024	<h2 id="code_ev_signal_code_signal_me_when_a"><code>ev_signal</code> - signal me when a signal gets signalled!</h2>
684	<div id="code_ev_signal_code_signal_me_when_a-2">	1025	<div id="code_ev_signal_code_signal_me_when_a-2">
685	<p>Signal watchers will trigger an event when the process receives a specific	1026	<p>Signal watchers will trigger an event when the process receives a specific
686	signal one or more times. Even though signals are very asynchronous, libev	1027	signal one or more times. Even though signals are very asynchronous, libev
687	will try it's best to deliver signals synchronously, i.e. as part of the	1028	will try it's best to deliver signals synchronously, i.e. as part of the
688	normal event processing, like any other event.</p>	1029	normal event processing, like any other event.</p>
…		…
699	<p>Configures the watcher to trigger on the given signal number (usually one	1040	<p>Configures the watcher to trigger on the given signal number (usually one
700	of the <code>SIGxxx</code> constants).</p>	1041	of the <code>SIGxxx</code> constants).</p>
701	</dd>	1042	</dd>
702	</dl>	1043	</dl>
703		1044
		1045
		1046
		1047
		1048
704	</div>	1049	</div>
705	<h2 id="code_ev_child_code_wait_for_pid_stat"><code>ev_child</code> - wait for pid status changes</h2>	1050	<h2 id="code_ev_child_code_watch_out_for_pro"><code>ev_child</code> - watch out for process status changes</h2>
706	<div id="code_ev_child_code_wait_for_pid_stat-2">	1051	<div id="code_ev_child_code_watch_out_for_pro-2">
707	<p>Child watchers trigger when your process receives a SIGCHLD in response to	1052	<p>Child watchers trigger when your process receives a SIGCHLD in response to
708	some child status changes (most typically when a child of yours dies).</p>	1053	some child status changes (most typically when a child of yours dies).</p>
709	<dl>	1054	<dl>
710	<dt>ev_child_init (ev_child *, callback, int pid)</dt>	1055	<dt>ev_child_init (ev_child *, callback, int pid)</dt>
711	<dt>ev_child_set (ev_child *, int pid)</dt>	1056	<dt>ev_child_set (ev_child *, int pid)</dt>
…		…
716	the status word (use the macros from <code>sys/wait.h</code> and see your systems	1061	the status word (use the macros from <code>sys/wait.h</code> and see your systems
717	<code>waitpid</code> documentation). The <code>rpid</code> member contains the pid of the	1062	<code>waitpid</code> documentation). The <code>rpid</code> member contains the pid of the
718	process causing the status change.</p>	1063	process causing the status change.</p>
719	</dd>	1064	</dd>
720	</dl>	1065	</dl>
		1066	<p>Example: try to exit cleanly on SIGINT and SIGTERM.</p>
		1067	<pre> static void
		1068	sigint_cb (struct ev_loop loop, struct ev_signal w, int revents)
		1069	{
		1070	ev_unloop (loop, EVUNLOOP_ALL);
		1071	}
721		1072
		1073	struct ev_signal signal_watcher;
		1074	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);
		1075	ev_signal_start (loop, &sigint_cb);
		1076
		1077
		1078
		1079
		1080	</pre>
		1081
722	</div>	1082	</div>
723	<h2 id="code_ev_idle_code_when_you_ve_got_no"><code>ev_idle</code> - when you've got nothing better to do</h2>	1083	<h2 id="code_ev_idle_code_when_you_ve_got_no"><code>ev_idle</code> - when you've got nothing better to do...</h2>
724	<div id="code_ev_idle_code_when_you_ve_got_no-2">	1084	<div id="code_ev_idle_code_when_you_ve_got_no-2">
725	<p>Idle watchers trigger events when there are no other events are pending	1085	<p>Idle watchers trigger events when there are no other events are pending
726	(prepare, check and other idle watchers do not count). That is, as long	1086	(prepare, check and other idle watchers do not count). That is, as long
727	as your process is busy handling sockets or timeouts (or even signals,	1087	as your process is busy handling sockets or timeouts (or even signals,
728	imagine) it will not be triggered. But when your process is idle all idle	1088	imagine) it will not be triggered. But when your process is idle all idle
…		…
741	<p>Initialises and configures the idle watcher - it has no parameters of any	1101	<p>Initialises and configures the idle watcher - it has no parameters of any
742	kind. There is a <code>ev_idle_set</code> macro, but using it is utterly pointless,	1102	kind. There is a <code>ev_idle_set</code> macro, but using it is utterly pointless,
743	believe me.</p>	1103	believe me.</p>
744	</dd>	1104	</dd>
745	</dl>	1105	</dl>
		1106	<p>Example: dynamically allocate an <code>ev_idle</code>, start it, and in the
		1107	callback, free it. Alos, use no error checking, as usual.</p>
		1108	<pre> static void
		1109	idle_cb (struct ev_loop loop, struct ev_idle w, int revents)
		1110	{
		1111	free (w);
		1112	// now do something you wanted to do when the program has
		1113	// no longer asnything immediate to do.
		1114	}
746		1115
		1116	struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle));
		1117	ev_idle_init (idle_watcher, idle_cb);
		1118	ev_idle_start (loop, idle_cb);
		1119
		1120
		1121
		1122
		1123	</pre>
		1124
747	</div>	1125	</div>
748	<h2 id="code_ev_prepare_code_and_code_ev_che"><code>ev_prepare</code> and <code>ev_check</code> - customise your event loop</h2>	1126	<h2 id="code_ev_prepare_code_and_code_ev_che"><code>ev_prepare</code> and <code>ev_check</code> - customise your event loop!</h2>
749	<div id="code_ev_prepare_code_and_code_ev_che-2">	1127	<div id="code_ev_prepare_code_and_code_ev_che-2">
750	<p>Prepare and check watchers are usually (but not always) used in tandem:	1128	<p>Prepare and check watchers are usually (but not always) used in tandem:
751	prepare watchers get invoked before the process blocks and check watchers	1129	prepare watchers get invoked before the process blocks and check watchers
752	afterwards.</p>	1130	afterwards.</p>
753	<p>Their main purpose is to integrate other event mechanisms into libev. This	1131	<p>Their main purpose is to integrate other event mechanisms into libev and
754	could be used, for example, to track variable changes, implement your own	1132	their use is somewhat advanced. This could be used, for example, to track
755	watchers, integrate net-snmp or a coroutine library and lots more.</p>	1133	variable changes, implement your own watchers, integrate net-snmp or a
		1134	coroutine library and lots more.</p>
756	<p>This is done by examining in each prepare call which file descriptors need	1135	<p>This is done by examining in each prepare call which file descriptors need
757	to be watched by the other library, registering <code>ev_io</code> watchers for	1136	to be watched by the other library, registering <code>ev_io</code> watchers for
758	them and starting an <code>ev_timer</code> watcher for any timeouts (many libraries	1137	them and starting an <code>ev_timer</code> watcher for any timeouts (many libraries
759	provide just this functionality). Then, in the check watcher you check for	1138	provide just this functionality). Then, in the check watcher you check for
760	any events that occured (by checking the pending status of all watchers	1139	any events that occured (by checking the pending status of all watchers
…		…
776	<p>Initialises and configures the prepare or check watcher - they have no	1155	<p>Initialises and configures the prepare or check watcher - they have no
777	parameters of any kind. There are <code>ev_prepare_set</code> and <code>ev_check_set</code>	1156	parameters of any kind. There are <code>ev_prepare_set</code> and <code>ev_check_set</code>
778	macros, but using them is utterly, utterly and completely pointless.</p>	1157	macros, but using them is utterly, utterly and completely pointless.</p>
779	</dd>	1158	</dd>
780	</dl>	1159	</dl>
		1160	<p>Example: TODO.</p>
		1161
		1162
		1163
		1164
		1165
		1166	</div>
		1167	<h2 id="code_ev_embed_code_when_one_backend_"><code>ev_embed</code> - when one backend isn't enough...</h2>
		1168	<div id="code_ev_embed_code_when_one_backend_-2">
		1169	<p>This is a rather advanced watcher type that lets you embed one event loop
		1170	into another (currently only <code>ev_io</code> events are supported in the embedded
		1171	loop, other types of watchers might be handled in a delayed or incorrect
		1172	fashion and must not be used).</p>
		1173	<p>There are primarily two reasons you would want that: work around bugs and
		1174	prioritise I/O.</p>
		1175	<p>As an example for a bug workaround, the kqueue backend might only support
		1176	sockets on some platform, so it is unusable as generic backend, but you
		1177	still want to make use of it because you have many sockets and it scales
		1178	so nicely. In this case, you would create a kqueue-based loop and embed it
		1179	into your default loop (which might use e.g. poll). Overall operation will
		1180	be a bit slower because first libev has to poll and then call kevent, but
		1181	at least you can use both at what they are best.</p>
		1182	<p>As for prioritising I/O: rarely you have the case where some fds have
		1183	to be watched and handled very quickly (with low latency), and even
		1184	priorities and idle watchers might have too much overhead. In this case
		1185	you would put all the high priority stuff in one loop and all the rest in
		1186	a second one, and embed the second one in the first.</p>
		1187	<p>As long as the watcher is active, the callback will be invoked every time
		1188	there might be events pending in the embedded loop. The callback must then
		1189	call <code>ev_embed_sweep (mainloop, watcher)</code> to make a single sweep and invoke
		1190	their callbacks (you could also start an idle watcher to give the embedded
		1191	loop strictly lower priority for example). You can also set the callback
		1192	to <code>0</code>, in which case the embed watcher will automatically execute the
		1193	embedded loop sweep.</p>
		1194	<p>As long as the watcher is started it will automatically handle events. The
		1195	callback will be invoked whenever some events have been handled. You can
		1196	set the callback to <code>0</code> to avoid having to specify one if you are not
		1197	interested in that.</p>
		1198	<p>Also, there have not currently been made special provisions for forking:
		1199	when you fork, you not only have to call <code>ev_loop_fork</code> on both loops,
		1200	but you will also have to stop and restart any <code>ev_embed</code> watchers
		1201	yourself.</p>
		1202	<p>Unfortunately, not all backends are embeddable, only the ones returned by
		1203	<code>ev_embeddable_backends</code> are, which, unfortunately, does not include any
		1204	portable one.</p>
		1205	<p>So when you want to use this feature you will always have to be prepared
		1206	that you cannot get an embeddable loop. The recommended way to get around
		1207	this is to have a separate variables for your embeddable loop, try to
		1208	create it, and if that fails, use the normal loop for everything:</p>
		1209	<pre> struct ev_loop *loop_hi = ev_default_init (0);
		1210	struct ev_loop *loop_lo = 0;
		1211	struct ev_embed embed;
		1212
		1213	// see if there is a chance of getting one that works
		1214	// (remember that a flags value of 0 means autodetection)
		1215	loop_lo = ev_embeddable_backends () & ev_recommended_backends ()
		1216	? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ())
		1217	: 0;
		1218
		1219	// if we got one, then embed it, otherwise default to loop_hi
		1220	if (loop_lo)
		1221	{
		1222	ev_embed_init (&embed, 0, loop_lo);
		1223	ev_embed_start (loop_hi, &embed);
		1224	}
		1225	else
		1226	loop_lo = loop_hi;
		1227
		1228	</pre>
		1229	<dl>
		1230	<dt>ev_embed_init (ev_embed , callback, struct ev_loop embedded_loop)</dt>
		1231	<dt>ev_embed_set (ev_embed , callback, struct ev_loop embedded_loop)</dt>
		1232	<dd>
		1233	<p>Configures the watcher to embed the given loop, which must be
		1234	embeddable. If the callback is <code>0</code>, then <code>ev_embed_sweep</code> will be
		1235	invoked automatically, otherwise it is the responsibility of the callback
		1236	to invoke it (it will continue to be called until the sweep has been done,
		1237	if you do not want thta, you need to temporarily stop the embed watcher).</p>
		1238	</dd>
		1239	<dt>ev_embed_sweep (loop, ev_embed *)</dt>
		1240	<dd>
		1241	<p>Make a single, non-blocking sweep over the embedded loop. This works
		1242	similarly to <code>ev_loop (embedded_loop, EVLOOP_NONBLOCK)</code>, but in the most
		1243	apropriate way for embedded loops.</p>
		1244	</dd>
		1245	</dl>
		1246
		1247
		1248
		1249
781		1250
782	</div>	1251	</div>
783	<h1 id="OTHER_FUNCTIONS">OTHER FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p>	1252	<h1 id="OTHER_FUNCTIONS">OTHER FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p>
784	<div id="OTHER_FUNCTIONS_CONTENT">	1253	<div id="OTHER_FUNCTIONS_CONTENT">
785	<p>There are some other functions of possible interest. Described. Here. Now.</p>	1254	<p>There are some other functions of possible interest. Described. Here. Now.</p>
…		…
812		1281
813	ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);	1282	ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);
814		1283
815	</pre>	1284	</pre>
816	</dd>	1285	</dd>
817	<dt>ev_feed_event (loop, watcher, int events)</dt>	1286	<dt>ev_feed_event (ev_loop , watcher , int revents)</dt>
818	<dd>	1287	<dd>
819	<p>Feeds the given event set into the event loop, as if the specified event	1288	<p>Feeds the given event set into the event loop, as if the specified event
820	had happened for the specified watcher (which must be a pointer to an	1289	had happened for the specified watcher (which must be a pointer to an
821	initialised but not necessarily started event watcher).</p>	1290	initialised but not necessarily started event watcher).</p>
822	</dd>	1291	</dd>
823	<dt>ev_feed_fd_event (loop, int fd, int revents)</dt>	1292	<dt>ev_feed_fd_event (ev_loop *, int fd, int revents)</dt>
824	<dd>	1293	<dd>
825	<p>Feed an event on the given fd, as if a file descriptor backend detected	1294	<p>Feed an event on the given fd, as if a file descriptor backend detected
826	the given events it.</p>	1295	the given events it.</p>
827	</dd>	1296	</dd>
828	<dt>ev_feed_signal_event (loop, int signum)</dt>	1297	<dt>ev_feed_signal_event (ev_loop *loop, int signum)</dt>
829	<dd>	1298	<dd>
830	<p>Feed an event as if the given signal occured (loop must be the default loop!).</p>	1299	<p>Feed an event as if the given signal occured (<code>loop</code> must be the default
		1300	loop!).</p>
831	</dd>	1301	</dd>
832	</dl>	1302	</dl>
		1303
		1304
		1305
		1306
833		1307
834	</div>	1308	</div>
835	<h1 id="LIBEVENT_EMULATION">LIBEVENT EMULATION</h1><p><a href="#TOP" class="toplink">Top</a></p>	1309	<h1 id="LIBEVENT_EMULATION">LIBEVENT EMULATION</h1><p><a href="#TOP" class="toplink">Top</a></p>
836	<div id="LIBEVENT_EMULATION_CONTENT">	1310	<div id="LIBEVENT_EMULATION_CONTENT">
837	<p>Libev offers a compatibility emulation layer for libevent. It cannot	1311	<p>Libev offers a compatibility emulation layer for libevent. It cannot
…		…
852	</dl>	1326	</dl>
853		1327
854	</div>	1328	</div>
855	<h1 id="C_SUPPORT">C++ SUPPORT</h1><p><a href="#TOP" class="toplink">Top</a></p>	1329	<h1 id="C_SUPPORT">C++ SUPPORT</h1><p><a href="#TOP" class="toplink">Top</a></p>
856	<div id="C_SUPPORT_CONTENT">	1330	<div id="C_SUPPORT_CONTENT">
857	<p>TBD.</p>	1331	<p>Libev comes with some simplistic wrapper classes for C++ that mainly allow
		1332	you to use some convinience methods to start/stop watchers and also change
		1333	the callback model to a model using method callbacks on objects.</p>
		1334	<p>To use it,</p>
		1335	<pre> #include <ev++.h>
		1336
		1337	</pre>
		1338	<p>(it is not installed by default). This automatically includes <cite>ev.h</cite>
		1339	and puts all of its definitions (many of them macros) into the global
		1340	namespace. All C++ specific things are put into the <code>ev</code> namespace.</p>
		1341	<p>It should support all the same embedding options as <cite>ev.h</cite>, most notably
		1342	<code>EV_MULTIPLICITY</code>.</p>
		1343	<p>Here is a list of things available in the <code>ev</code> namespace:</p>
		1344	<dl>
		1345	<dt><code>ev::READ</code>, <code>ev::WRITE</code> etc.</dt>
		1346	<dd>
		1347	<p>These are just enum values with the same values as the <code>EV_READ</code> etc.
		1348	macros from <cite>ev.h</cite>.</p>
		1349	</dd>
		1350	<dt><code>ev::tstamp</code>, <code>ev::now</code></dt>
		1351	<dd>
		1352	<p>Aliases to the same types/functions as with the <code>ev_</code> prefix.</p>
		1353	</dd>
		1354	<dt><code>ev::io</code>, <code>ev::timer</code>, <code>ev::periodic</code>, <code>ev::idle</code>, <code>ev::sig</code> etc.</dt>
		1355	<dd>
		1356	<p>For each <code>ev_TYPE</code> watcher in <cite>ev.h</cite> there is a corresponding class of
		1357	the same name in the <code>ev</code> namespace, with the exception of <code>ev_signal</code>
		1358	which is called <code>ev::sig</code> to avoid clashes with the <code>signal</code> macro
		1359	defines by many implementations.</p>
		1360	<p>All of those classes have these methods:</p>
		1361	<p>
		1362	<dl>
		1363	<dt>ev::TYPE::TYPE (object , object::method )</dt>
		1364	<dt>ev::TYPE::TYPE (object , object::method , struct ev_loop *)</dt>
		1365	<dt>ev::TYPE::~TYPE</dt>
		1366	<dd>
		1367	<p>The constructor takes a pointer to an object and a method pointer to
		1368	the event handler callback to call in this class. The constructor calls
		1369	<code>ev_init</code> for you, which means you have to call the <code>set</code> method
		1370	before starting it. If you do not specify a loop then the constructor
		1371	automatically associates the default loop with this watcher.</p>
		1372	<p>The destructor automatically stops the watcher if it is active.</p>
		1373	</dd>
		1374	<dt>w->set (struct ev_loop *)</dt>
		1375	<dd>
		1376	<p>Associates a different <code>struct ev_loop</code> with this watcher. You can only
		1377	do this when the watcher is inactive (and not pending either).</p>
		1378	</dd>
		1379	<dt>w->set ([args])</dt>
		1380	<dd>
		1381	<p>Basically the same as <code>ev_TYPE_set</code>, with the same args. Must be
		1382	called at least once. Unlike the C counterpart, an active watcher gets
		1383	automatically stopped and restarted.</p>
		1384	</dd>
		1385	<dt>w->start ()</dt>
		1386	<dd>
		1387	<p>Starts the watcher. Note that there is no <code>loop</code> argument as the
		1388	constructor already takes the loop.</p>
		1389	</dd>
		1390	<dt>w->stop ()</dt>
		1391	<dd>
		1392	<p>Stops the watcher if it is active. Again, no <code>loop</code> argument.</p>
		1393	</dd>
		1394	<dt>w->again () <code>ev::timer</code>, <code>ev::periodic</code> only</dt>
		1395	<dd>
		1396	<p>For <code>ev::timer</code> and <code>ev::periodic</code>, this invokes the corresponding
		1397	<code>ev_TYPE_again</code> function.</p>
		1398	</dd>
		1399	<dt>w->sweep () <code>ev::embed</code> only</dt>
		1400	<dd>
		1401	<p>Invokes <code>ev_embed_sweep</code>.</p>
		1402	</dd>
		1403	</dl>
		1404	</p>
		1405	</dd>
		1406	</dl>
		1407	<p>Example: Define a class with an IO and idle watcher, start one of them in
		1408	the constructor.</p>
		1409	<pre> class myclass
		1410	{
		1411	ev_io io; void io_cb (ev::io &w, int revents);
		1412	ev_idle idle void idle_cb (ev::idle &w, int revents);
		1413
		1414	myclass ();
		1415	}
		1416
		1417	myclass::myclass (int fd)
		1418	: io (this, &myclass::io_cb),
		1419	idle (this, &myclass::idle_cb)
		1420	{
		1421	io.start (fd, ev::READ);
		1422	}
		1423
		1424	</pre>
		1425
		1426	</div>
		1427	<h1 id="EMBEDDING">EMBEDDING</h1><p><a href="#TOP" class="toplink">Top</a></p>
		1428	<div id="EMBEDDING_CONTENT">
		1429	<p>Libev can (and often is) directly embedded into host
		1430	applications. Examples of applications that embed it include the Deliantra
		1431	Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe)
		1432	and rxvt-unicode.</p>
		1433	<p>The goal is to enable you to just copy the neecssary files into your
		1434	source directory without having to change even a single line in them, so
		1435	you can easily upgrade by simply copying (or having a checked-out copy of
		1436	libev somewhere in your source tree).</p>
		1437
		1438	</div>
		1439	<h2 id="FILESETS">FILESETS</h2>
		1440	<div id="FILESETS_CONTENT">
		1441	<p>Depending on what features you need you need to include one or more sets of files
		1442	in your app.</p>
		1443
		1444	</div>
		1445	<h3 id="CORE_EVENT_LOOP">CORE EVENT LOOP</h3>
		1446	<div id="CORE_EVENT_LOOP_CONTENT">
		1447	<p>To include only the libev core (all the <code>ev_*</code> functions), with manual
		1448	configuration (no autoconf):</p>
		1449	<pre> #define EV_STANDALONE 1
		1450	#include "ev.c"
		1451
		1452	</pre>
		1453	<p>This will automatically include <cite>ev.h</cite>, too, and should be done in a
		1454	single C source file only to provide the function implementations. To use
		1455	it, do the same for <cite>ev.h</cite> in all files wishing to use this API (best
		1456	done by writing a wrapper around <cite>ev.h</cite> that you can include instead and
		1457	where you can put other configuration options):</p>
		1458	<pre> #define EV_STANDALONE 1
		1459	#include "ev.h"
		1460
		1461	</pre>
		1462	<p>Both header files and implementation files can be compiled with a C++
		1463	compiler (at least, thats a stated goal, and breakage will be treated
		1464	as a bug).</p>
		1465	<p>You need the following files in your source tree, or in a directory
		1466	in your include path (e.g. in libev/ when using -Ilibev):</p>
		1467	<pre> ev.h
		1468	ev.c
		1469	ev_vars.h
		1470	ev_wrap.h
		1471
		1472	ev_win32.c required on win32 platforms only
		1473
		1474	ev_select.c only when select backend is enabled (which is by default)
		1475	ev_poll.c only when poll backend is enabled (disabled by default)
		1476	ev_epoll.c only when the epoll backend is enabled (disabled by default)
		1477	ev_kqueue.c only when the kqueue backend is enabled (disabled by default)
		1478	ev_port.c only when the solaris port backend is enabled (disabled by default)
		1479
		1480	</pre>
		1481	<p><cite>ev.c</cite> includes the backend files directly when enabled, so you only need
		1482	to compile this single file.</p>
		1483
		1484	</div>
		1485	<h3 id="LIBEVENT_COMPATIBILITY_API">LIBEVENT COMPATIBILITY API</h3>
		1486	<div id="LIBEVENT_COMPATIBILITY_API_CONTENT">
		1487	<p>To include the libevent compatibility API, also include:</p>
		1488	<pre> #include "event.c"
		1489
		1490	</pre>
		1491	<p>in the file including <cite>ev.c</cite>, and:</p>
		1492	<pre> #include "event.h"
		1493
		1494	</pre>
		1495	<p>in the files that want to use the libevent API. This also includes <cite>ev.h</cite>.</p>
		1496	<p>You need the following additional files for this:</p>
		1497	<pre> event.h
		1498	event.c
		1499
		1500	</pre>
		1501
		1502	</div>
		1503	<h3 id="AUTOCONF_SUPPORT">AUTOCONF SUPPORT</h3>
		1504	<div id="AUTOCONF_SUPPORT_CONTENT">
		1505	<p>Instead of using <code>EV_STANDALONE=1</code> and providing your config in
		1506	whatever way you want, you can also <code>m4_include([libev.m4])</code> in your
		1507	<cite>configure.ac</cite> and leave <code>EV_STANDALONE</code> undefined. <cite>ev.c</cite> will then
		1508	include <cite>config.h</cite> and configure itself accordingly.</p>
		1509	<p>For this of course you need the m4 file:</p>
		1510	<pre> libev.m4
		1511
		1512	</pre>
		1513
		1514	</div>
		1515	<h2 id="PREPROCESSOR_SYMBOLS_MACROS">PREPROCESSOR SYMBOLS/MACROS</h2>
		1516	<div id="PREPROCESSOR_SYMBOLS_MACROS_CONTENT">
		1517	<p>Libev can be configured via a variety of preprocessor symbols you have to define
		1518	before including any of its files. The default is not to build for multiplicity
		1519	and only include the select backend.</p>
		1520	<dl>
		1521	<dt>EV_STANDALONE</dt>
		1522	<dd>
		1523	<p>Must always be <code>1</code> if you do not use autoconf configuration, which
		1524	keeps libev from including <cite>config.h</cite>, and it also defines dummy
		1525	implementations for some libevent functions (such as logging, which is not
		1526	supported). It will also not define any of the structs usually found in
		1527	<cite>event.h</cite> that are not directly supported by the libev core alone.</p>
		1528	</dd>
		1529	<dt>EV_USE_MONOTONIC</dt>
		1530	<dd>
		1531	<p>If defined to be <code>1</code>, libev will try to detect the availability of the
		1532	monotonic clock option at both compiletime and runtime. Otherwise no use
		1533	of the monotonic clock option will be attempted. If you enable this, you
		1534	usually have to link against librt or something similar. Enabling it when
		1535	the functionality isn't available is safe, though, althoguh you have
		1536	to make sure you link against any libraries where the <code>clock_gettime</code>
		1537	function is hiding in (often <cite>-lrt</cite>).</p>
		1538	</dd>
		1539	<dt>EV_USE_REALTIME</dt>
		1540	<dd>
		1541	<p>If defined to be <code>1</code>, libev will try to detect the availability of the
		1542	realtime clock option at compiletime (and assume its availability at
		1543	runtime if successful). Otherwise no use of the realtime clock option will
		1544	be attempted. This effectively replaces <code>gettimeofday</code> by <code>clock_get
		1545	(CLOCK_REALTIME, ...)</code> and will not normally affect correctness. See tzhe note about libraries
		1546	in the description of <code>EV_USE_MONOTONIC</code>, though.</p>
		1547	</dd>
		1548	<dt>EV_USE_SELECT</dt>
		1549	<dd>
		1550	<p>If undefined or defined to be <code>1</code>, libev will compile in support for the
		1551	<code>select</code>(2) backend. No attempt at autodetection will be done: if no
		1552	other method takes over, select will be it. Otherwise the select backend
		1553	will not be compiled in.</p>
		1554	</dd>
		1555	<dt>EV_SELECT_USE_FD_SET</dt>
		1556	<dd>
		1557	<p>If defined to <code>1</code>, then the select backend will use the system <code>fd_set</code>
		1558	structure. This is useful if libev doesn't compile due to a missing
		1559	<code>NFDBITS</code> or <code>fd_mask</code> definition or it misguesses the bitset layout on
		1560	exotic systems. This usually limits the range of file descriptors to some
		1561	low limit such as 1024 or might have other limitations (winsocket only
		1562	allows 64 sockets). The <code>FD_SETSIZE</code> macro, set before compilation, might
		1563	influence the size of the <code>fd_set</code> used.</p>
		1564	</dd>
		1565	<dt>EV_SELECT_IS_WINSOCKET</dt>
		1566	<dd>
		1567	<p>When defined to <code>1</code>, the select backend will assume that
		1568	select/socket/connect etc. don't understand file descriptors but
		1569	wants osf handles on win32 (this is the case when the select to
		1570	be used is the winsock select). This means that it will call
		1571	<code>_get_osfhandle</code> on the fd to convert it to an OS handle. Otherwise,
		1572	it is assumed that all these functions actually work on fds, even
		1573	on win32. Should not be defined on non-win32 platforms.</p>
		1574	</dd>
		1575	<dt>EV_USE_POLL</dt>
		1576	<dd>
		1577	<p>If defined to be <code>1</code>, libev will compile in support for the <code>poll</code>(2)
		1578	backend. Otherwise it will be enabled on non-win32 platforms. It
		1579	takes precedence over select.</p>
		1580	</dd>
		1581	<dt>EV_USE_EPOLL</dt>
		1582	<dd>
		1583	<p>If defined to be <code>1</code>, libev will compile in support for the Linux
		1584	<code>epoll</code>(7) backend. Its availability will be detected at runtime,
		1585	otherwise another method will be used as fallback. This is the
		1586	preferred backend for GNU/Linux systems.</p>
		1587	</dd>
		1588	<dt>EV_USE_KQUEUE</dt>
		1589	<dd>
		1590	<p>If defined to be <code>1</code>, libev will compile in support for the BSD style
		1591	<code>kqueue</code>(2) backend. Its actual availability will be detected at runtime,
		1592	otherwise another method will be used as fallback. This is the preferred
		1593	backend for BSD and BSD-like systems, although on most BSDs kqueue only
		1594	supports some types of fds correctly (the only platform we found that
		1595	supports ptys for example was NetBSD), so kqueue might be compiled in, but
		1596	not be used unless explicitly requested. The best way to use it is to find
		1597	out whether kqueue supports your type of fd properly and use an embedded
		1598	kqueue loop.</p>
		1599	</dd>
		1600	<dt>EV_USE_PORT</dt>
		1601	<dd>
		1602	<p>If defined to be <code>1</code>, libev will compile in support for the Solaris
		1603	10 port style backend. Its availability will be detected at runtime,
		1604	otherwise another method will be used as fallback. This is the preferred
		1605	backend for Solaris 10 systems.</p>
		1606	</dd>
		1607	<dt>EV_USE_DEVPOLL</dt>
		1608	<dd>
		1609	<p>reserved for future expansion, works like the USE symbols above.</p>
		1610	</dd>
		1611	<dt>EV_H</dt>
		1612	<dd>
		1613	<p>The name of the <cite>ev.h</cite> header file used to include it. The default if
		1614	undefined is <code><ev.h></code> in <cite>event.h</cite> and <code>"ev.h"</code> in <cite>ev.c</cite>. This
		1615	can be used to virtually rename the <cite>ev.h</cite> header file in case of conflicts.</p>
		1616	</dd>
		1617	<dt>EV_CONFIG_H</dt>
		1618	<dd>
		1619	<p>If <code>EV_STANDALONE</code> isn't <code>1</code>, this variable can be used to override
		1620	<cite>ev.c</cite>'s idea of where to find the <cite>config.h</cite> file, similarly to
		1621	<code>EV_H</code>, above.</p>
		1622	</dd>
		1623	<dt>EV_EVENT_H</dt>
		1624	<dd>
		1625	<p>Similarly to <code>EV_H</code>, this macro can be used to override <cite>event.c</cite>'s idea
		1626	of how the <cite>event.h</cite> header can be found.</p>
		1627	</dd>
		1628	<dt>EV_PROTOTYPES</dt>
		1629	<dd>
		1630	<p>If defined to be <code>0</code>, then <cite>ev.h</cite> will not define any function
		1631	prototypes, but still define all the structs and other symbols. This is
		1632	occasionally useful if you want to provide your own wrapper functions
		1633	around libev functions.</p>
		1634	</dd>
		1635	<dt>EV_MULTIPLICITY</dt>
		1636	<dd>
		1637	<p>If undefined or defined to <code>1</code>, then all event-loop-specific functions
		1638	will have the <code>struct ev_loop *</code> as first argument, and you can create
		1639	additional independent event loops. Otherwise there will be no support
		1640	for multiple event loops and there is no first event loop pointer
		1641	argument. Instead, all functions act on the single default loop.</p>
		1642	</dd>
		1643	<dt>EV_PERIODICS</dt>
		1644	<dd>
		1645	<p>If undefined or defined to be <code>1</code>, then periodic timers are supported,
		1646	otherwise not. This saves a few kb of code.</p>
		1647	</dd>
		1648	<dt>EV_COMMON</dt>
		1649	<dd>
		1650	<p>By default, all watchers have a <code>void *data</code> member. By redefining
		1651	this macro to a something else you can include more and other types of
		1652	members. You have to define it each time you include one of the files,
		1653	though, and it must be identical each time.</p>
		1654	<p>For example, the perl EV module uses something like this:</p>
		1655	<pre> #define EV_COMMON \
		1656	SV self; / contains this struct */ \
		1657	SV cb_sv, fh /* note no trailing ";" */
		1658
		1659	</pre>
		1660	</dd>
		1661	<dt>EV_CB_DECLARE (type)</dt>
		1662	<dt>EV_CB_INVOKE (watcher, revents)</dt>
		1663	<dt>ev_set_cb (ev, cb)</dt>
		1664	<dd>
		1665	<p>Can be used to change the callback member declaration in each watcher,
		1666	and the way callbacks are invoked and set. Must expand to a struct member
		1667	definition and a statement, respectively. See the <cite>ev.v</cite> header file for
		1668	their default definitions. One possible use for overriding these is to
		1669	avoid the <code>struct ev_loop *</code> as first argument in all cases, or to use
		1670	method calls instead of plain function calls in C++.</p>
		1671
		1672	</div>
		1673	<h2 id="EXAMPLES">EXAMPLES</h2>
		1674	<div id="EXAMPLES_CONTENT">
		1675	<p>For a real-world example of a program the includes libev
		1676	verbatim, you can have a look at the EV perl module
		1677	(<a href="http://software.schmorp.de/pkg/EV.html">http://software.schmorp.de/pkg/EV.html</a>). It has the libev files in
		1678	the <cite>libev/</cite> subdirectory and includes them in the <cite>EV/EVAPI.h</cite> (public
		1679	interface) and <cite>EV.xs</cite> (implementation) files. Only the <cite>EV.xs</cite> file
		1680	will be compiled. It is pretty complex because it provides its own header
		1681	file.</p>
		1682	<p>The usage in rxvt-unicode is simpler. It has a <cite>ev_cpp.h</cite> header file
		1683	that everybody includes and which overrides some autoconf choices:</p>
		1684	<pre> #define EV_USE_POLL 0
		1685	#define EV_MULTIPLICITY 0
		1686	#define EV_PERIODICS 0
		1687	#define EV_CONFIG_H <config.h>
		1688
		1689	#include "ev++.h"
		1690
		1691	</pre>
		1692	<p>And a <cite>ev_cpp.C</cite> implementation file that contains libev proper and is compiled:</p>
		1693	<pre> #include "ev_cpp.h"
		1694	#include "ev.c"
		1695
		1696	</pre>
858		1697
859	</div>	1698	</div>
860	<h1 id="AUTHOR">AUTHOR</h1><p><a href="#TOP" class="toplink">Top</a></p>	1699	<h1 id="AUTHOR">AUTHOR</h1><p><a href="#TOP" class="toplink">Top</a></p>
861	<div id="AUTHOR_CONTENT">	1700	<div id="AUTHOR_CONTENT">
862	<p>Marc Lehmann <libev@schmorp.de>.</p>	1701	<p>Marc Lehmann <libev@schmorp.de>.</p>
863		1702
864	</div>	1703	</div>
865	</div></body>	1704	</div></body>
866	</html>	1705	</html>

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Revision 1.45 by root, Sat Nov 24 16:57:39 2007 UTC