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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="Fri Nov 23 16:26:06 2007" />	9	<meta name="created" content="Mon Nov 26 11:20:35 2007" />
10	<meta name="generator" content="Pod::Xhtml 1.57" />	10	<meta name="generator" content="Pod::Xhtml 1.57" />
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12	<body>	12	<body>
13	<div class="pod">	13	<div class="pod">
14	<!-- INDEX START -->	14	<!-- INDEX START -->
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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>
		55	<li><a href="#COMPLEXITIES">COMPLEXITIES</a></li>
42	<li><a href="#AUTHOR">AUTHOR</a>	56	<li><a href="#AUTHOR">AUTHOR</a>
43	</li>	57	</li>
44	</ul><hr />	58	</ul><hr />
45	<!-- INDEX END -->	59	<!-- INDEX END -->
46		60
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96	<div id="TIME_REPRESENTATION_CONTENT">	110	<div id="TIME_REPRESENTATION_CONTENT">
97	<p>Libev represents time as a single floating point number, representing the	111	<p>Libev represents time as a single floating point number, representing the
98	(fractional) number of seconds since the (POSIX) epoch (somewhere near	112	(fractional) number of seconds since the (POSIX) epoch (somewhere near
99	the beginning of 1970, details are complicated, don't ask). This type is	113	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	114	called <code>ev_tstamp</code>, which is what you should use too. It usually aliases
101	to the double type in C.</p>	115	to the <code>double</code> type in C, and when you need to do any calculations on
		116	it, you should treat it as such.</p>
		117
		118
		119
		120
102		121
103	</div>	122	</div>
104	<h1 id="GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p>	123	<h1 id="GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p>
105	<div id="GLOBAL_FUNCTIONS_CONTENT">	124	<div id="GLOBAL_FUNCTIONS_CONTENT">
106	<p>These functions can be called anytime, even before initialising the	125	<p>These functions can be called anytime, even before initialising the
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122	version of the library your program was compiled against.</p>	141	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,	142	<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	143	as this indicates an incompatible change. Minor versions are usually
125	compatible to older versions, so a larger minor version alone is usually	144	compatible to older versions, so a larger minor version alone is usually
126	not a problem.</p>	145	not a problem.</p>
		146	<p>Example: make sure we haven't accidentally been linked against the wrong
		147	version:</p>
		148	<pre> assert (("libev version mismatch",
		149	ev_version_major () == EV_VERSION_MAJOR
		150	&& ev_version_minor () >= EV_VERSION_MINOR));
		151
		152	</pre>
127	</dd>	153	</dd>
128	<dt>unsigned int ev_supported_backends ()</dt>	154	<dt>unsigned int ev_supported_backends ()</dt>
129	<dd>	155	<dd>
130	<p>Return the set of all backends (i.e. their corresponding <code>EV_BACKEND_*</code>	156	<p>Return the set of all backends (i.e. their corresponding <code>EV_BACKEND_*</code>
131	value) compiled into this binary of libev (independent of their	157	value) compiled into this binary of libev (independent of their
132	availability on the system you are running on). See <code>ev_default_loop</code> for	158	availability on the system you are running on). See <code>ev_default_loop</code> for
133	a description of the set values.</p>	159	a description of the set values.</p>
		160	<p>Example: make sure we have the epoll method, because yeah this is cool and
		161	a must have and can we have a torrent of it please!!!11</p>
		162	<pre> assert (("sorry, no epoll, no sex",
		163	ev_supported_backends () & EVBACKEND_EPOLL));
		164
		165	</pre>
134	</dd>	166	</dd>
135	<dt>unsigned int ev_recommended_backends ()</dt>	167	<dt>unsigned int ev_recommended_backends ()</dt>
136	<dd>	168	<dd>
137	<p>Return the set of all backends compiled into this binary of libev and also	169	<p>Return the set of all backends compiled into this binary of libev and also
138	recommended for this platform. This set is often smaller than the one	170	recommended for this platform. This set is often smaller than the one
139	returned by <code>ev_supported_backends</code>, as for example kqueue is broken on	171	returned by <code>ev_supported_backends</code>, as for example kqueue is broken on
140	most BSDs and will not be autodetected unless you explicitly request it	172	most BSDs and will not be autodetected unless you explicitly request it
141	(assuming you know what you are doing). This is the set of backends that	173	(assuming you know what you are doing). This is the set of backends that
142	libev will probe for if you specify no backends explicitly.</p>	174	libev will probe for if you specify no backends explicitly.</p>
		175	</dd>
		176	<dt>unsigned int ev_embeddable_backends ()</dt>
		177	<dd>
		178	<p>Returns the set of backends that are embeddable in other event loops. This
		179	is the theoretical, all-platform, value. To find which backends
		180	might be supported on the current system, you would need to look at
		181	<code>ev_embeddable_backends () & ev_supported_backends ()</code>, likewise for
		182	recommended ones.</p>
		183	<p>See the description of <code>ev_embed</code> watchers for more info.</p>
143	</dd>	184	</dd>
144	<dt>ev_set_allocator (void (cb)(void *ptr, long size))</dt>	185	<dt>ev_set_allocator (void (cb)(void *ptr, long size))</dt>
145	<dd>	186	<dd>
146	<p>Sets the allocation function to use (the prototype is similar to the	187	<p>Sets the allocation function to use (the prototype is similar to the
147	realloc C function, the semantics are identical). It is used to allocate	188	realloc C function, the semantics are identical). It is used to allocate
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149	needs to be allocated, the library might abort or take some potentially	190	needs to be allocated, the library might abort or take some potentially
150	destructive action. The default is your system realloc function.</p>	191	destructive action. The default is your system realloc function.</p>
151	<p>You could override this function in high-availability programs to, say,	192	<p>You could override this function in high-availability programs to, say,
152	free some memory if it cannot allocate memory, to use a special allocator,	193	free some memory if it cannot allocate memory, to use a special allocator,
153	or even to sleep a while and retry until some memory is available.</p>	194	or even to sleep a while and retry until some memory is available.</p>
		195	<p>Example: replace the libev allocator with one that waits a bit and then
		196	retries: better than mine).</p>
		197	<pre> static void *
		198	persistent_realloc (void *ptr, long size)
		199	{
		200	for (;;)
		201	{
		202	void *newptr = realloc (ptr, size);
		203
		204	if (newptr)
		205	return newptr;
		206
		207	sleep (60);
		208	}
		209	}
		210
		211	...
		212	ev_set_allocator (persistent_realloc);
		213
		214	</pre>
154	</dd>	215	</dd>
155	<dt>ev_set_syserr_cb (void (cb)(const char msg));</dt>	216	<dt>ev_set_syserr_cb (void (cb)(const char msg));</dt>
156	<dd>	217	<dd>
157	<p>Set the callback function to call on a retryable syscall error (such	218	<p>Set the callback function to call on a retryable syscall error (such
158	as failed select, poll, epoll_wait). The message is a printable string	219	as failed select, poll, epoll_wait). The message is a printable string
159	indicating the system call or subsystem causing the problem. If this	220	indicating the system call or subsystem causing the problem. If this
160	callback is set, then libev will expect it to remedy the sitution, no	221	callback is set, then libev will expect it to remedy the sitution, no
161	matter what, when it returns. That is, libev will generally retry the	222	matter what, when it returns. That is, libev will generally retry the
162	requested operation, or, if the condition doesn't go away, do bad stuff	223	requested operation, or, if the condition doesn't go away, do bad stuff
163	(such as abort).</p>	224	(such as abort).</p>
		225	<p>Example: do the same thing as libev does internally:</p>
		226	<pre> static void
		227	fatal_error (const char *msg)
		228	{
		229	perror (msg);
		230	abort ();
		231	}
		232
		233	...
		234	ev_set_syserr_cb (fatal_error);
		235
		236	</pre>
164	</dd>	237	</dd>
165	</dl>	238	</dl>
166		239
167	</div>	240	</div>
168	<h1 id="FUNCTIONS_CONTROLLING_THE_EVENT_LOOP">FUNCTIONS CONTROLLING THE EVENT LOOP</h1><p><a href="#TOP" class="toplink">Top</a></p>	241	<h1 id="FUNCTIONS_CONTROLLING_THE_EVENT_LOOP">FUNCTIONS CONTROLLING THE EVENT LOOP</h1><p><a href="#TOP" class="toplink">Top</a></p>
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293	<dd>	366	<dd>
294	<p>Similar to <code>ev_default_loop</code>, but always creates a new event loop that is	367	<p>Similar to <code>ev_default_loop</code>, but always creates a new event loop that is
295	always distinct from the default loop. Unlike the default loop, it cannot	368	always distinct from the default loop. Unlike the default loop, it cannot
296	handle signal and child watchers, and attempts to do so will be greeted by	369	handle signal and child watchers, and attempts to do so will be greeted by
297	undefined behaviour (or a failed assertion if assertions are enabled).</p>	370	undefined behaviour (or a failed assertion if assertions are enabled).</p>
		371	<p>Example: try to create a event loop that uses epoll and nothing else.</p>
		372	<pre> struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL \| EVFLAG_NOENV);
		373	if (!epoller)
		374	fatal ("no epoll found here, maybe it hides under your chair");
		375
		376	</pre>
298	</dd>	377	</dd>
299	<dt>ev_default_destroy ()</dt>	378	<dt>ev_default_destroy ()</dt>
300	<dd>	379	<dd>
301	<p>Destroys the default loop again (frees all memory and kernel state	380	<p>Destroys the default loop again (frees all memory and kernel state
302	etc.). This stops all registered event watchers (by not touching them in	381	etc.). None of the active event watchers will be stopped in the normal
303	any way whatsoever, although you cannot rely on this :).</p>	382	sense, so e.g. <code>ev_is_active</code> might still return true. It is your
		383	responsibility to either stop all watchers cleanly yoursef <i>before</i>
		384	calling this function, or cope with the fact afterwards (which is usually
		385	the easiest thing, youc na just ignore the watchers and/or <code>free ()</code> them
		386	for example).</p>
304	</dd>	387	</dd>
305	<dt>ev_loop_destroy (loop)</dt>	388	<dt>ev_loop_destroy (loop)</dt>
306	<dd>	389	<dd>
307	<p>Like <code>ev_default_destroy</code>, but destroys an event loop created by an	390	<p>Like <code>ev_default_destroy</code>, but destroys an event loop created by an
308	earlier call to <code>ev_loop_new</code>.</p>	391	earlier call to <code>ev_loop_new</code>.</p>
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338	use.</p>	421	use.</p>
339	</dd>	422	</dd>
340	<dt>ev_tstamp ev_now (loop)</dt>	423	<dt>ev_tstamp ev_now (loop)</dt>
341	<dd>	424	<dd>
342	<p>Returns the current "event loop time", which is the time the event loop	425	<p>Returns the current "event loop time", which is the time the event loop
343	got events and started processing them. This timestamp does not change	426	received events and started processing them. This timestamp does not
344	as long as callbacks are being processed, and this is also the base time	427	change as long as callbacks are being processed, and this is also the base
345	used for relative timers. You can treat it as the timestamp of the event	428	time used for relative timers. You can treat it as the timestamp of the
346	occuring (or more correctly, the mainloop finding out about it).</p>	429	event occuring (or more correctly, libev finding out about it).</p>
347	</dd>	430	</dd>
348	<dt>ev_loop (loop, int flags)</dt>	431	<dt>ev_loop (loop, int flags)</dt>
349	<dd>	432	<dd>
350	<p>Finally, this is it, the event handler. This function usually is called	433	<p>Finally, this is it, the event handler. This function usually is called
351	after you initialised all your watchers and you want to start handling	434	after you initialised all your watchers and you want to start handling
352	events.</p>	435	events.</p>
353	<p>If the flags argument is specified as <code>0</code>, it will not return until	436	<p>If the flags argument is specified as <code>0</code>, it will not return until
354	either no event watchers are active anymore or <code>ev_unloop</code> was called.</p>	437	either no event watchers are active anymore or <code>ev_unloop</code> was called.</p>
		438	<p>Please note that an explicit <code>ev_unloop</code> is usually better than
		439	relying on all watchers to be stopped when deciding when a program has
		440	finished (especially in interactive programs), but having a program that
		441	automatically loops as long as it has to and no longer by virtue of
		442	relying on its watchers stopping correctly is a thing of beauty.</p>
355	<p>A flags value of <code>EVLOOP_NONBLOCK</code> will look for new events, will handle	443	<p>A flags value of <code>EVLOOP_NONBLOCK</code> will look for new events, will handle
356	those events and any outstanding ones, but will not block your process in	444	those events and any outstanding ones, but will not block your process in
357	case there are no events and will return after one iteration of the loop.</p>	445	case there are no events and will return after one iteration of the loop.</p>
358	<p>A flags value of <code>EVLOOP_ONESHOT</code> will look for new events (waiting if	446	<p>A flags value of <code>EVLOOP_ONESHOT</code> will look for new events (waiting if
359	neccessary) and will handle those and any outstanding ones. It will block	447	neccessary) and will handle those and any outstanding ones. It will block
…		…
381	be handled here by queueing them when their watcher gets executed.	469	be handled here by queueing them when their watcher gets executed.
382	- If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK	470	- If ev_unloop has been called or EVLOOP_ONESHOT or EVLOOP_NONBLOCK
383	were used, return, otherwise continue with step *.	471	were used, return, otherwise continue with step *.
384		472
385	</pre>	473	</pre>
		474	<p>Example: queue some jobs and then loop until no events are outsanding
		475	anymore.</p>
		476	<pre> ... queue jobs here, make sure they register event watchers as long
		477	... as they still have work to do (even an idle watcher will do..)
		478	ev_loop (my_loop, 0);
		479	... jobs done. yeah!
		480
		481	</pre>
386	</dd>	482	</dd>
387	<dt>ev_unloop (loop, how)</dt>	483	<dt>ev_unloop (loop, how)</dt>
388	<dd>	484	<dd>
389	<p>Can be used to make a call to <code>ev_loop</code> return early (but only after it	485	<p>Can be used to make a call to <code>ev_loop</code> return early (but only after it
390	has processed all outstanding events). The <code>how</code> argument must be either	486	has processed all outstanding events). The <code>how</code> argument must be either
…		…
402	example, libev itself uses this for its internal signal pipe: It is not	498	example, libev itself uses this for its internal signal pipe: It is not
403	visible to the libev user and should not keep <code>ev_loop</code> from exiting if	499	visible to the libev user and should not keep <code>ev_loop</code> from exiting if
404	no event watchers registered by it are active. It is also an excellent	500	no event watchers registered by it are active. It is also an excellent
405	way to do this for generic recurring timers or from within third-party	501	way to do this for generic recurring timers or from within third-party
406	libraries. Just remember to <i>unref after start</i> and <i>ref before stop</i>.</p>	502	libraries. Just remember to <i>unref after start</i> and <i>ref before stop</i>.</p>
		503	<p>Example: create a signal watcher, but keep it from keeping <code>ev_loop</code>
		504	running when nothing else is active.</p>
		505	<pre> struct dv_signal exitsig;
		506	ev_signal_init (&exitsig, sig_cb, SIGINT);
		507	ev_signal_start (myloop, &exitsig);
		508	evf_unref (myloop);
		509
		510	</pre>
		511	<p>Example: for some weird reason, unregister the above signal handler again.</p>
		512	<pre> ev_ref (myloop);
		513	ev_signal_stop (myloop, &exitsig);
		514
		515	</pre>
407	</dd>	516	</dd>
408	</dl>	517	</dl>
		518
		519
		520
		521
409		522
410	</div>	523	</div>
411	<h1 id="ANATOMY_OF_A_WATCHER">ANATOMY OF A WATCHER</h1><p><a href="#TOP" class="toplink">Top</a></p>	524	<h1 id="ANATOMY_OF_A_WATCHER">ANATOMY OF A WATCHER</h1><p><a href="#TOP" class="toplink">Top</a></p>
412	<div id="ANATOMY_OF_A_WATCHER_CONTENT">	525	<div id="ANATOMY_OF_A_WATCHER_CONTENT">
413	<p>A watcher is a structure that you create and register to record your	526	<p>A watcher is a structure that you create and register to record your
…		…
443	with a watcher-specific start function (<code>ev_<type>_start (loop, watcher	556	with a watcher-specific start function (<code>ev_<type>_start (loop, watcher
444	*)</code>), and you can stop watching for events at any time by calling the	557	*)</code>), and you can stop watching for events at any time by calling the
445	corresponding stop function (<code>ev_<type>_stop (loop, watcher *)</code>.</p>	558	corresponding stop function (<code>ev_<type>_stop (loop, watcher *)</code>.</p>
446	<p>As long as your watcher is active (has been started but not stopped) you	559	<p>As long as your watcher is active (has been started but not stopped) you
447	must not touch the values stored in it. Most specifically you must never	560	must not touch the values stored in it. Most specifically you must never
448	reinitialise it or call its set macro.</p>	561	reinitialise it or call its <code>set</code> macro.</p>
449	<p>You can check whether an event is active by calling the <code>ev_is_active
450	(watcher *)</code> macro. To see whether an event is outstanding (but the
451	callback for it has not been called yet) you can use the <code>ev_is_pending
452	(watcher *)</code> macro.</p>
453	<p>Each and every callback receives the event loop pointer as first, the	562	<p>Each and every callback receives the event loop pointer as first, the
454	registered watcher structure as second, and a bitset of received events as	563	registered watcher structure as second, and a bitset of received events as
455	third argument.</p>	564	third argument.</p>
456	<p>The received events usually include a single bit per event type received	565	<p>The received events usually include a single bit per event type received
457	(you can receive multiple events at the same time). The possible bit masks	566	(you can receive multiple events at the same time). The possible bit masks
…		…
506	your callbacks is well-written it can just attempt the operation and cope	615	your callbacks is well-written it can just attempt the operation and cope
507	with the error from read() or write(). This will not work in multithreaded	616	with the error from read() or write(). This will not work in multithreaded
508	programs, though, so beware.</p>	617	programs, though, so beware.</p>
509	</dd>	618	</dd>
510	</dl>	619	</dl>
		620
		621	</div>
		622	<h2 id="GENERIC_WATCHER_FUNCTIONS">GENERIC WATCHER FUNCTIONS</h2>
		623	<div id="GENERIC_WATCHER_FUNCTIONS_CONTENT">
		624	<p>In the following description, <code>TYPE</code> stands for the watcher type,
		625	e.g. <code>timer</code> for <code>ev_timer</code> watchers and <code>io</code> for <code>ev_io</code> watchers.</p>
		626	<dl>
		627	<dt><code>ev_init</code> (ev_TYPE *watcher, callback)</dt>
		628	<dd>
		629	<p>This macro initialises the generic portion of a watcher. The contents
		630	of the watcher object can be arbitrary (so <code>malloc</code> will do). Only
		631	the generic parts of the watcher are initialised, you <i>need</i> to call
		632	the type-specific <code>ev_TYPE_set</code> macro afterwards to initialise the
		633	type-specific parts. For each type there is also a <code>ev_TYPE_init</code> macro
		634	which rolls both calls into one.</p>
		635	<p>You can reinitialise a watcher at any time as long as it has been stopped
		636	(or never started) and there are no pending events outstanding.</p>
		637	<p>The callback is always of type <code>void ()(ev_loop loop, ev_TYPE *watcher,
		638	int revents)</code>.</p>
		639	</dd>
		640	<dt><code>ev_TYPE_set</code> (ev_TYPE *, [args])</dt>
		641	<dd>
		642	<p>This macro initialises the type-specific parts of a watcher. You need to
		643	call <code>ev_init</code> at least once before you call this macro, but you can
		644	call <code>ev_TYPE_set</code> any number of times. You must not, however, call this
		645	macro on a watcher that is active (it can be pending, however, which is a
		646	difference to the <code>ev_init</code> macro).</p>
		647	<p>Although some watcher types do not have type-specific arguments
		648	(e.g. <code>ev_prepare</code>) you still need to call its <code>set</code> macro.</p>
		649	</dd>
		650	<dt><code>ev_TYPE_init</code> (ev_TYPE *watcher, callback, [args])</dt>
		651	<dd>
		652	<p>This convinience macro rolls both <code>ev_init</code> and <code>ev_TYPE_set</code> macro
		653	calls into a single call. This is the most convinient method to initialise
		654	a watcher. The same limitations apply, of course.</p>
		655	</dd>
		656	<dt><code>ev_TYPE_start</code> (loop , ev_TYPE watcher)</dt>
		657	<dd>
		658	<p>Starts (activates) the given watcher. Only active watchers will receive
		659	events. If the watcher is already active nothing will happen.</p>
		660	</dd>
		661	<dt><code>ev_TYPE_stop</code> (loop , ev_TYPE watcher)</dt>
		662	<dd>
		663	<p>Stops the given watcher again (if active) and clears the pending
		664	status. It is possible that stopped watchers are pending (for example,
		665	non-repeating timers are being stopped when they become pending), but
		666	<code>ev_TYPE_stop</code> ensures that the watcher is neither active nor pending. If
		667	you want to free or reuse the memory used by the watcher it is therefore a
		668	good idea to always call its <code>ev_TYPE_stop</code> function.</p>
		669	</dd>
		670	<dt>bool ev_is_active (ev_TYPE *watcher)</dt>
		671	<dd>
		672	<p>Returns a true value iff the watcher is active (i.e. it has been started
		673	and not yet been stopped). As long as a watcher is active you must not modify
		674	it.</p>
		675	</dd>
		676	<dt>bool ev_is_pending (ev_TYPE *watcher)</dt>
		677	<dd>
		678	<p>Returns a true value iff the watcher is pending, (i.e. it has outstanding
		679	events but its callback has not yet been invoked). As long as a watcher
		680	is pending (but not active) you must not call an init function on it (but
		681	<code>ev_TYPE_set</code> is safe) and you must make sure the watcher is available to
		682	libev (e.g. you cnanot <code>free ()</code> it).</p>
		683	</dd>
		684	<dt>callback = ev_cb (ev_TYPE *watcher)</dt>
		685	<dd>
		686	<p>Returns the callback currently set on the watcher.</p>
		687	</dd>
		688	<dt>ev_cb_set (ev_TYPE *watcher, callback)</dt>
		689	<dd>
		690	<p>Change the callback. You can change the callback at virtually any time
		691	(modulo threads).</p>
		692	</dd>
		693	</dl>
		694
		695
		696
		697
511		698
512	</div>	699	</div>
513	<h2 id="ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH">ASSOCIATING CUSTOM DATA WITH A WATCHER</h2>	700	<h2 id="ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH">ASSOCIATING CUSTOM DATA WITH A WATCHER</h2>
514	<div id="ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH-2">	701	<div id="ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH-2">
515	<p>Each watcher has, by default, a member <code>void *data</code> that you can change	702	<p>Each watcher has, by default, a member <code>void *data</code> that you can change
…		…
547	<h1 id="WATCHER_TYPES">WATCHER TYPES</h1><p><a href="#TOP" class="toplink">Top</a></p>	734	<h1 id="WATCHER_TYPES">WATCHER TYPES</h1><p><a href="#TOP" class="toplink">Top</a></p>
548	<div id="WATCHER_TYPES_CONTENT">	735	<div id="WATCHER_TYPES_CONTENT">
549	<p>This section describes each watcher in detail, but will not repeat	736	<p>This section describes each watcher in detail, but will not repeat
550	information given in the last section.</p>	737	information given in the last section.</p>
551		738
		739
		740
		741
		742
552	</div>	743	</div>
553	<h2 id="code_ev_io_code_is_this_file_descrip"><code>ev_io</code> - is this file descriptor readable or writable</h2>	744	<h2 id="code_ev_io_code_is_this_file_descrip"><code>ev_io</code> - is this file descriptor readable or writable?</h2>
554	<div id="code_ev_io_code_is_this_file_descrip-2">	745	<div id="code_ev_io_code_is_this_file_descrip-2">
555	<p>I/O watchers check whether a file descriptor is readable or writable	746	<p>I/O watchers check whether a file descriptor is readable or writable
556	in each iteration of the event loop (This behaviour is called	747	in each iteration of the event loop, or, more precisely, when reading
557	level-triggering because you keep receiving events as long as the	748	would not block the process and writing would at least be able to write
558	condition persists. Remember you can stop the watcher if you don't want to	749	some data. This behaviour is called level-triggering because you keep
559	act on the event and neither want to receive future events).</p>	750	receiving events as long as the condition persists. Remember you can stop
		751	the watcher if you don't want to act on the event and neither want to
		752	receive future events.</p>
560	<p>In general you can register as many read and/or write event watchers per	753	<p>In general you can register as many read and/or write event watchers per
561	fd as you want (as long as you don't confuse yourself). Setting all file	754	fd as you want (as long as you don't confuse yourself). Setting all file
562	descriptors to non-blocking mode is also usually a good idea (but not	755	descriptors to non-blocking mode is also usually a good idea (but not
563	required if you know what you are doing).</p>	756	required if you know what you are doing).</p>
564	<p>You have to be careful with dup'ed file descriptors, though. Some backends	757	<p>You have to be careful with dup'ed file descriptors, though. Some backends
565	(the linux epoll backend is a notable example) cannot handle dup'ed file	758	(the linux epoll backend is a notable example) cannot handle dup'ed file
566	descriptors correctly if you register interest in two or more fds pointing	759	descriptors correctly if you register interest in two or more fds pointing
567	to the same underlying file/socket etc. description (that is, they share	760	to the same underlying file/socket/etc. description (that is, they share
568	the same underlying "file open").</p>	761	the same underlying "file open").</p>
569	<p>If you must do this, then force the use of a known-to-be-good backend	762	<p>If you must do this, then force the use of a known-to-be-good backend
570	(at the time of this writing, this includes only <code>EVBACKEND_SELECT</code> and	763	(at the time of this writing, this includes only <code>EVBACKEND_SELECT</code> and
571	<code>EVBACKEND_POLL</code>).</p>	764	<code>EVBACKEND_POLL</code>).</p>
		765	<p>Another thing you have to watch out for is that it is quite easy to
		766	receive "spurious" readyness notifications, that is your callback might
		767	be called with <code>EV_READ</code> but a subsequent <code>read</code>(2) will actually block
		768	because there is no data. Not only are some backends known to create a
		769	lot of those (for example solaris ports), it is very easy to get into
		770	this situation even with a relatively standard program structure. Thus
		771	it is best to always use non-blocking I/O: An extra <code>read</code>(2) returning
		772	<code>EAGAIN</code> is far preferable to a program hanging until some data arrives.</p>
		773	<p>If you cannot run the fd in non-blocking mode (for example you should not
		774	play around with an Xlib connection), then you have to seperately re-test
		775	wether a file descriptor is really ready with a known-to-be good interface
		776	such as poll (fortunately in our Xlib example, Xlib already does this on
		777	its own, so its quite safe to use).</p>
572	<dl>	778	<dl>
573	<dt>ev_io_init (ev_io *, callback, int fd, int events)</dt>	779	<dt>ev_io_init (ev_io *, callback, int fd, int events)</dt>
574	<dt>ev_io_set (ev_io *, int fd, int events)</dt>	780	<dt>ev_io_set (ev_io *, int fd, int events)</dt>
575	<dd>	781	<dd>
576	<p>Configures an <code>ev_io</code> watcher. The fd is the file descriptor to rceeive	782	<p>Configures an <code>ev_io</code> watcher. The <code>fd</code> is the file descriptor to
577	events for and events is either <code>EV_READ</code>, <code>EV_WRITE</code> or <code>EV_READ \|	783	rceeive events for and events is either <code>EV_READ</code>, <code>EV_WRITE</code> or
578	EV_WRITE</code> to receive the given events.</p>	784	<code>EV_READ \| EV_WRITE</code> to receive the given events.</p>
579	<p>Please note that most of the more scalable backend mechanisms (for example
580	epoll and solaris ports) can result in spurious readyness notifications
581	for file descriptors, so you practically need to use non-blocking I/O (and
582	treat callback invocation as hint only), or retest separately with a safe
583	interface before doing I/O (XLib can do this), or force the use of either
584	<code>EVBACKEND_SELECT</code> or <code>EVBACKEND_POLL</code>, which don't suffer from this
585	problem. Also note that it is quite easy to have your callback invoked
586	when the readyness condition is no longer valid even when employing
587	typical ways of handling events, so its a good idea to use non-blocking
588	I/O unconditionally.</p>
589	</dd>	785	</dd>
590	</dl>	786	</dl>
		787	<p>Example: call <code>stdin_readable_cb</code> when STDIN_FILENO has become, well
		788	readable, but only once. Since it is likely line-buffered, you could
		789	attempt to read a whole line in the callback:</p>
		790	<pre> static void
		791	stdin_readable_cb (struct ev_loop loop, struct ev_io w, int revents)
		792	{
		793	ev_io_stop (loop, w);
		794	.. read from stdin here (or from w->fd) and haqndle any I/O errors
		795	}
591		796
		797	...
		798	struct ev_loop *loop = ev_default_init (0);
		799	struct ev_io stdin_readable;
		800	ev_io_init (&stdin_readable, stdin_readable_cb, STDIN_FILENO, EV_READ);
		801	ev_io_start (loop, &stdin_readable);
		802	ev_loop (loop, 0);
		803
		804
		805
		806
		807	</pre>
		808
592	</div>	809	</div>
593	<h2 id="code_ev_timer_code_relative_and_opti"><code>ev_timer</code> - relative and optionally recurring timeouts</h2>	810	<h2 id="code_ev_timer_code_relative_and_opti"><code>ev_timer</code> - relative and optionally repeating timeouts</h2>
594	<div id="code_ev_timer_code_relative_and_opti-2">	811	<div id="code_ev_timer_code_relative_and_opti-2">
595	<p>Timer watchers are simple relative timers that generate an event after a	812	<p>Timer watchers are simple relative timers that generate an event after a
596	given time, and optionally repeating in regular intervals after that.</p>	813	given time, and optionally repeating in regular intervals after that.</p>
597	<p>The timers are based on real time, that is, if you register an event that	814	<p>The timers are based on real time, that is, if you register an event that
598	times out after an hour and you reset your system clock to last years	815	times out after an hour and you reset your system clock to last years
…		…
639	time you successfully read or write some data. If you go into an idle	856	time you successfully read or write some data. If you go into an idle
640	state where you do not expect data to travel on the socket, you can stop	857	state where you do not expect data to travel on the socket, you can stop
641	the timer, and again will automatically restart it if need be.</p>	858	the timer, and again will automatically restart it if need be.</p>
642	</dd>	859	</dd>
643	</dl>	860	</dl>
		861	<p>Example: create a timer that fires after 60 seconds.</p>
		862	<pre> static void
		863	one_minute_cb (struct ev_loop loop, struct ev_timer w, int revents)
		864	{
		865	.. one minute over, w is actually stopped right here
		866	}
644		867
		868	struct ev_timer mytimer;
		869	ev_timer_init (&mytimer, one_minute_cb, 60., 0.);
		870	ev_timer_start (loop, &mytimer);
		871
		872	</pre>
		873	<p>Example: create a timeout timer that times out after 10 seconds of
		874	inactivity.</p>
		875	<pre> static void
		876	timeout_cb (struct ev_loop loop, struct ev_timer w, int revents)
		877	{
		878	.. ten seconds without any activity
		879	}
		880
		881	struct ev_timer mytimer;
		882	ev_timer_init (&mytimer, timeout_cb, 0., 10.); /* note, only repeat used */
		883	ev_timer_again (&mytimer); /* start timer */
		884	ev_loop (loop, 0);
		885
		886	// and in some piece of code that gets executed on any "activity":
		887	// reset the timeout to start ticking again at 10 seconds
		888	ev_timer_again (&mytimer);
		889
		890
		891
		892
		893	</pre>
		894
645	</div>	895	</div>
646	<h2 id="code_ev_periodic_code_to_cron_or_not"><code>ev_periodic</code> - to cron or not to cron</h2>	896	<h2 id="code_ev_periodic_code_to_cron_or_not"><code>ev_periodic</code> - to cron or not to cron?</h2>
647	<div id="code_ev_periodic_code_to_cron_or_not-2">	897	<div id="code_ev_periodic_code_to_cron_or_not-2">
648	<p>Periodic watchers are also timers of a kind, but they are very versatile	898	<p>Periodic watchers are also timers of a kind, but they are very versatile
649	(and unfortunately a bit complex).</p>	899	(and unfortunately a bit complex).</p>
650	<p>Unlike <code>ev_timer</code>'s, they are not based on real time (or relative time)	900	<p>Unlike <code>ev_timer</code>'s, they are not based on real time (or relative time)
651	but on wallclock time (absolute time). You can tell a periodic watcher	901	but on wallclock time (absolute time). You can tell a periodic watcher
652	to trigger "at" some specific point in time. For example, if you tell a	902	to trigger "at" some specific point in time. For example, if you tell a
653	periodic watcher to trigger in 10 seconds (by specifiying e.g. c<ev_now ()	903	periodic watcher to trigger in 10 seconds (by specifiying e.g. <code>ev_now ()
654	+ 10.>) and then reset your system clock to the last year, then it will	904	+ 10.</code>) and then reset your system clock to the last year, then it will
655	take a year to trigger the event (unlike an <code>ev_timer</code>, which would trigger	905	take a year to trigger the event (unlike an <code>ev_timer</code>, which would trigger
656	roughly 10 seconds later and of course not if you reset your system time	906	roughly 10 seconds later and of course not if you reset your system time
657	again).</p>	907	again).</p>
658	<p>They can also be used to implement vastly more complex timers, such as	908	<p>They can also be used to implement vastly more complex timers, such as
659	triggering an event on eahc midnight, local time.</p>	909	triggering an event on eahc midnight, local time.</p>
…		…
732	when you changed some parameters or the reschedule callback would return	982	when you changed some parameters or the reschedule callback would return
733	a different time than the last time it was called (e.g. in a crond like	983	a different time than the last time it was called (e.g. in a crond like
734	program when the crontabs have changed).</p>	984	program when the crontabs have changed).</p>
735	</dd>	985	</dd>
736	</dl>	986	</dl>
		987	<p>Example: call a callback every hour, or, more precisely, whenever the
		988	system clock is divisible by 3600. The callback invocation times have
		989	potentially a lot of jittering, but good long-term stability.</p>
		990	<pre> static void
		991	clock_cb (struct ev_loop loop, struct ev_io w, int revents)
		992	{
		993	... its now a full hour (UTC, or TAI or whatever your clock follows)
		994	}
737		995
		996	struct ev_periodic hourly_tick;
		997	ev_periodic_init (&hourly_tick, clock_cb, 0., 3600., 0);
		998	ev_periodic_start (loop, &hourly_tick);
		999
		1000	</pre>
		1001	<p>Example: the same as above, but use a reschedule callback to do it:</p>
		1002	<pre> #include <math.h>
		1003
		1004	static ev_tstamp
		1005	my_scheduler_cb (struct ev_periodic *w, ev_tstamp now)
		1006	{
		1007	return fmod (now, 3600.) + 3600.;
		1008	}
		1009
		1010	ev_periodic_init (&hourly_tick, clock_cb, 0., 0., my_scheduler_cb);
		1011
		1012	</pre>
		1013	<p>Example: call a callback every hour, starting now:</p>
		1014	<pre> struct ev_periodic hourly_tick;
		1015	ev_periodic_init (&hourly_tick, clock_cb,
		1016	fmod (ev_now (loop), 3600.), 3600., 0);
		1017	ev_periodic_start (loop, &hourly_tick);
		1018
		1019
		1020
		1021
		1022	</pre>
		1023
738	</div>	1024	</div>
739	<h2 id="code_ev_signal_code_signal_me_when_a"><code>ev_signal</code> - signal me when a signal gets signalled</h2>	1025	<h2 id="code_ev_signal_code_signal_me_when_a"><code>ev_signal</code> - signal me when a signal gets signalled!</h2>
740	<div id="code_ev_signal_code_signal_me_when_a-2">	1026	<div id="code_ev_signal_code_signal_me_when_a-2">
741	<p>Signal watchers will trigger an event when the process receives a specific	1027	<p>Signal watchers will trigger an event when the process receives a specific
742	signal one or more times. Even though signals are very asynchronous, libev	1028	signal one or more times. Even though signals are very asynchronous, libev
743	will try it's best to deliver signals synchronously, i.e. as part of the	1029	will try it's best to deliver signals synchronously, i.e. as part of the
744	normal event processing, like any other event.</p>	1030	normal event processing, like any other event.</p>
…		…
755	<p>Configures the watcher to trigger on the given signal number (usually one	1041	<p>Configures the watcher to trigger on the given signal number (usually one
756	of the <code>SIGxxx</code> constants).</p>	1042	of the <code>SIGxxx</code> constants).</p>
757	</dd>	1043	</dd>
758	</dl>	1044	</dl>
759		1045
		1046
		1047
		1048
		1049
760	</div>	1050	</div>
761	<h2 id="code_ev_child_code_wait_for_pid_stat"><code>ev_child</code> - wait for pid status changes</h2>	1051	<h2 id="code_ev_child_code_watch_out_for_pro"><code>ev_child</code> - watch out for process status changes</h2>
762	<div id="code_ev_child_code_wait_for_pid_stat-2">	1052	<div id="code_ev_child_code_watch_out_for_pro-2">
763	<p>Child watchers trigger when your process receives a SIGCHLD in response to	1053	<p>Child watchers trigger when your process receives a SIGCHLD in response to
764	some child status changes (most typically when a child of yours dies).</p>	1054	some child status changes (most typically when a child of yours dies).</p>
765	<dl>	1055	<dl>
766	<dt>ev_child_init (ev_child *, callback, int pid)</dt>	1056	<dt>ev_child_init (ev_child *, callback, int pid)</dt>
767	<dt>ev_child_set (ev_child *, int pid)</dt>	1057	<dt>ev_child_set (ev_child *, int pid)</dt>
…		…
772	the status word (use the macros from <code>sys/wait.h</code> and see your systems	1062	the status word (use the macros from <code>sys/wait.h</code> and see your systems
773	<code>waitpid</code> documentation). The <code>rpid</code> member contains the pid of the	1063	<code>waitpid</code> documentation). The <code>rpid</code> member contains the pid of the
774	process causing the status change.</p>	1064	process causing the status change.</p>
775	</dd>	1065	</dd>
776	</dl>	1066	</dl>
		1067	<p>Example: try to exit cleanly on SIGINT and SIGTERM.</p>
		1068	<pre> static void
		1069	sigint_cb (struct ev_loop loop, struct ev_signal w, int revents)
		1070	{
		1071	ev_unloop (loop, EVUNLOOP_ALL);
		1072	}
777		1073
		1074	struct ev_signal signal_watcher;
		1075	ev_signal_init (&signal_watcher, sigint_cb, SIGINT);
		1076	ev_signal_start (loop, &sigint_cb);
		1077
		1078
		1079
		1080
		1081	</pre>
		1082
778	</div>	1083	</div>
779	<h2 id="code_ev_idle_code_when_you_ve_got_no"><code>ev_idle</code> - when you've got nothing better to do</h2>	1084	<h2 id="code_ev_idle_code_when_you_ve_got_no"><code>ev_idle</code> - when you've got nothing better to do...</h2>
780	<div id="code_ev_idle_code_when_you_ve_got_no-2">	1085	<div id="code_ev_idle_code_when_you_ve_got_no-2">
781	<p>Idle watchers trigger events when there are no other events are pending	1086	<p>Idle watchers trigger events when there are no other events are pending
782	(prepare, check and other idle watchers do not count). That is, as long	1087	(prepare, check and other idle watchers do not count). That is, as long
783	as your process is busy handling sockets or timeouts (or even signals,	1088	as your process is busy handling sockets or timeouts (or even signals,
784	imagine) it will not be triggered. But when your process is idle all idle	1089	imagine) it will not be triggered. But when your process is idle all idle
…		…
797	<p>Initialises and configures the idle watcher - it has no parameters of any	1102	<p>Initialises and configures the idle watcher - it has no parameters of any
798	kind. There is a <code>ev_idle_set</code> macro, but using it is utterly pointless,	1103	kind. There is a <code>ev_idle_set</code> macro, but using it is utterly pointless,
799	believe me.</p>	1104	believe me.</p>
800	</dd>	1105	</dd>
801	</dl>	1106	</dl>
		1107	<p>Example: dynamically allocate an <code>ev_idle</code>, start it, and in the
		1108	callback, free it. Alos, use no error checking, as usual.</p>
		1109	<pre> static void
		1110	idle_cb (struct ev_loop loop, struct ev_idle w, int revents)
		1111	{
		1112	free (w);
		1113	// now do something you wanted to do when the program has
		1114	// no longer asnything immediate to do.
		1115	}
802		1116
		1117	struct ev_idle *idle_watcher = malloc (sizeof (struct ev_idle));
		1118	ev_idle_init (idle_watcher, idle_cb);
		1119	ev_idle_start (loop, idle_cb);
		1120
		1121
		1122
		1123
		1124	</pre>
		1125
803	</div>	1126	</div>
804	<h2 id="code_ev_prepare_code_and_code_ev_che"><code>ev_prepare</code> and <code>ev_check</code> - customise your event loop</h2>	1127	<h2 id="code_ev_prepare_code_and_code_ev_che"><code>ev_prepare</code> and <code>ev_check</code> - customise your event loop!</h2>
805	<div id="code_ev_prepare_code_and_code_ev_che-2">	1128	<div id="code_ev_prepare_code_and_code_ev_che-2">
806	<p>Prepare and check watchers are usually (but not always) used in tandem:	1129	<p>Prepare and check watchers are usually (but not always) used in tandem:
807	prepare watchers get invoked before the process blocks and check watchers	1130	prepare watchers get invoked before the process blocks and check watchers
808	afterwards.</p>	1131	afterwards.</p>
		1132	<p>You <i>must not</i> call <code>ev_loop</code> or similar functions that enter
		1133	the current event loop from either <code>ev_prepare</code> or <code>ev_check</code>
		1134	watchers. Other loops than the current one are fine, however. The
		1135	rationale behind this is that you do not need to check for recursion in
		1136	those watchers, i.e. the sequence will always be <code>ev_prepare</code>, blocking,
		1137	<code>ev_check</code> so if you have one watcher of each kind they will always be
		1138	called in pairs bracketing the blocking call.</p>
809	<p>Their main purpose is to integrate other event mechanisms into libev. This	1139	<p>Their main purpose is to integrate other event mechanisms into libev and
810	could be used, for example, to track variable changes, implement your own	1140	their use is somewhat advanced. This could be used, for example, to track
811	watchers, integrate net-snmp or a coroutine library and lots more.</p>	1141	variable changes, implement your own watchers, integrate net-snmp or a
		1142	coroutine library and lots more. They are also occasionally useful if
		1143	you cache some data and want to flush it before blocking (for example,
		1144	in X programs you might want to do an <code>XFlush ()</code> in an <code>ev_prepare</code>
		1145	watcher).</p>
812	<p>This is done by examining in each prepare call which file descriptors need	1146	<p>This is done by examining in each prepare call which file descriptors need
813	to be watched by the other library, registering <code>ev_io</code> watchers for	1147	to be watched by the other library, registering <code>ev_io</code> watchers for
814	them and starting an <code>ev_timer</code> watcher for any timeouts (many libraries	1148	them and starting an <code>ev_timer</code> watcher for any timeouts (many libraries
815	provide just this functionality). Then, in the check watcher you check for	1149	provide just this functionality). Then, in the check watcher you check for
816	any events that occured (by checking the pending status of all watchers	1150	any events that occured (by checking the pending status of all watchers
…		…
832	<p>Initialises and configures the prepare or check watcher - they have no	1166	<p>Initialises and configures the prepare or check watcher - they have no
833	parameters of any kind. There are <code>ev_prepare_set</code> and <code>ev_check_set</code>	1167	parameters of any kind. There are <code>ev_prepare_set</code> and <code>ev_check_set</code>
834	macros, but using them is utterly, utterly and completely pointless.</p>	1168	macros, but using them is utterly, utterly and completely pointless.</p>
835	</dd>	1169	</dd>
836	</dl>	1170	</dl>
		1171	<p>Example: To include a library such as adns, you would add IO watchers
		1172	and a timeout watcher in a prepare handler, as required by libadns, and
		1173	in a check watcher, destroy them and call into libadns. What follows is
		1174	pseudo-code only of course:</p>
		1175	<pre> static ev_io iow [nfd];
		1176	static ev_timer tw;
		1177
		1178	static void
		1179	io_cb (ev_loop loop, ev_io w, int revents)
		1180	{
		1181	// set the relevant poll flags
		1182	// could also call adns_processreadable etc. here
		1183	struct pollfd fd = (struct pollfd )w->data;
		1184	if (revents & EV_READ ) fd->revents \|= fd->events & POLLIN;
		1185	if (revents & EV_WRITE) fd->revents \|= fd->events & POLLOUT;
		1186	}
		1187
		1188	// create io watchers for each fd and a timer before blocking
		1189	static void
		1190	adns_prepare_cb (ev_loop loop, ev_prepare w, int revents)
		1191	{
		1192	int timeout = 3600000;truct pollfd fds [nfd];
		1193	// actual code will need to loop here and realloc etc.
		1194	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));
		1195
		1196	/* the callback is illegal, but won't be called as we stop during check */
		1197	ev_timer_init (&tw, 0, timeout * 1e-3);
		1198	ev_timer_start (loop, &tw);
		1199
		1200	// create on ev_io per pollfd
		1201	for (int i = 0; i < nfd; ++i)
		1202	{
		1203	ev_io_init (iow + i, io_cb, fds [i].fd,
		1204	((fds [i].events & POLLIN ? EV_READ : 0)
		1205	\| (fds [i].events & POLLOUT ? EV_WRITE : 0)));
		1206
		1207	fds [i].revents = 0;
		1208	iow [i].data = fds + i;
		1209	ev_io_start (loop, iow + i);
		1210	}
		1211	}
		1212
		1213	// stop all watchers after blocking
		1214	static void
		1215	adns_check_cb (ev_loop loop, ev_check w, int revents)
		1216	{
		1217	ev_timer_stop (loop, &tw);
		1218
		1219	for (int i = 0; i < nfd; ++i)
		1220	ev_io_stop (loop, iow + i);
		1221
		1222	adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));
		1223	}
		1224
		1225
		1226
		1227
		1228	</pre>
		1229
		1230	</div>
		1231	<h2 id="code_ev_embed_code_when_one_backend_"><code>ev_embed</code> - when one backend isn't enough...</h2>
		1232	<div id="code_ev_embed_code_when_one_backend_-2">
		1233	<p>This is a rather advanced watcher type that lets you embed one event loop
		1234	into another (currently only <code>ev_io</code> events are supported in the embedded
		1235	loop, other types of watchers might be handled in a delayed or incorrect
		1236	fashion and must not be used).</p>
		1237	<p>There are primarily two reasons you would want that: work around bugs and
		1238	prioritise I/O.</p>
		1239	<p>As an example for a bug workaround, the kqueue backend might only support
		1240	sockets on some platform, so it is unusable as generic backend, but you
		1241	still want to make use of it because you have many sockets and it scales
		1242	so nicely. In this case, you would create a kqueue-based loop and embed it
		1243	into your default loop (which might use e.g. poll). Overall operation will
		1244	be a bit slower because first libev has to poll and then call kevent, but
		1245	at least you can use both at what they are best.</p>
		1246	<p>As for prioritising I/O: rarely you have the case where some fds have
		1247	to be watched and handled very quickly (with low latency), and even
		1248	priorities and idle watchers might have too much overhead. In this case
		1249	you would put all the high priority stuff in one loop and all the rest in
		1250	a second one, and embed the second one in the first.</p>
		1251	<p>As long as the watcher is active, the callback will be invoked every time
		1252	there might be events pending in the embedded loop. The callback must then
		1253	call <code>ev_embed_sweep (mainloop, watcher)</code> to make a single sweep and invoke
		1254	their callbacks (you could also start an idle watcher to give the embedded
		1255	loop strictly lower priority for example). You can also set the callback
		1256	to <code>0</code>, in which case the embed watcher will automatically execute the
		1257	embedded loop sweep.</p>
		1258	<p>As long as the watcher is started it will automatically handle events. The
		1259	callback will be invoked whenever some events have been handled. You can
		1260	set the callback to <code>0</code> to avoid having to specify one if you are not
		1261	interested in that.</p>
		1262	<p>Also, there have not currently been made special provisions for forking:
		1263	when you fork, you not only have to call <code>ev_loop_fork</code> on both loops,
		1264	but you will also have to stop and restart any <code>ev_embed</code> watchers
		1265	yourself.</p>
		1266	<p>Unfortunately, not all backends are embeddable, only the ones returned by
		1267	<code>ev_embeddable_backends</code> are, which, unfortunately, does not include any
		1268	portable one.</p>
		1269	<p>So when you want to use this feature you will always have to be prepared
		1270	that you cannot get an embeddable loop. The recommended way to get around
		1271	this is to have a separate variables for your embeddable loop, try to
		1272	create it, and if that fails, use the normal loop for everything:</p>
		1273	<pre> struct ev_loop *loop_hi = ev_default_init (0);
		1274	struct ev_loop *loop_lo = 0;
		1275	struct ev_embed embed;
		1276
		1277	// see if there is a chance of getting one that works
		1278	// (remember that a flags value of 0 means autodetection)
		1279	loop_lo = ev_embeddable_backends () & ev_recommended_backends ()
		1280	? ev_loop_new (ev_embeddable_backends () & ev_recommended_backends ())
		1281	: 0;
		1282
		1283	// if we got one, then embed it, otherwise default to loop_hi
		1284	if (loop_lo)
		1285	{
		1286	ev_embed_init (&embed, 0, loop_lo);
		1287	ev_embed_start (loop_hi, &embed);
		1288	}
		1289	else
		1290	loop_lo = loop_hi;
		1291
		1292	</pre>
		1293	<dl>
		1294	<dt>ev_embed_init (ev_embed , callback, struct ev_loop embedded_loop)</dt>
		1295	<dt>ev_embed_set (ev_embed , callback, struct ev_loop embedded_loop)</dt>
		1296	<dd>
		1297	<p>Configures the watcher to embed the given loop, which must be
		1298	embeddable. If the callback is <code>0</code>, then <code>ev_embed_sweep</code> will be
		1299	invoked automatically, otherwise it is the responsibility of the callback
		1300	to invoke it (it will continue to be called until the sweep has been done,
		1301	if you do not want thta, you need to temporarily stop the embed watcher).</p>
		1302	</dd>
		1303	<dt>ev_embed_sweep (loop, ev_embed *)</dt>
		1304	<dd>
		1305	<p>Make a single, non-blocking sweep over the embedded loop. This works
		1306	similarly to <code>ev_loop (embedded_loop, EVLOOP_NONBLOCK)</code>, but in the most
		1307	apropriate way for embedded loops.</p>
		1308	</dd>
		1309	</dl>
		1310
		1311
		1312
		1313
837		1314
838	</div>	1315	</div>
839	<h1 id="OTHER_FUNCTIONS">OTHER FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p>	1316	<h1 id="OTHER_FUNCTIONS">OTHER FUNCTIONS</h1><p><a href="#TOP" class="toplink">Top</a></p>
840	<div id="OTHER_FUNCTIONS_CONTENT">	1317	<div id="OTHER_FUNCTIONS_CONTENT">
841	<p>There are some other functions of possible interest. Described. Here. Now.</p>	1318	<p>There are some other functions of possible interest. Described. Here. Now.</p>
…		…
868		1345
869	ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);	1346	ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);
870		1347
871	</pre>	1348	</pre>
872	</dd>	1349	</dd>
873	<dt>ev_feed_event (loop, watcher, int events)</dt>	1350	<dt>ev_feed_event (ev_loop , watcher , int revents)</dt>
874	<dd>	1351	<dd>
875	<p>Feeds the given event set into the event loop, as if the specified event	1352	<p>Feeds the given event set into the event loop, as if the specified event
876	had happened for the specified watcher (which must be a pointer to an	1353	had happened for the specified watcher (which must be a pointer to an
877	initialised but not necessarily started event watcher).</p>	1354	initialised but not necessarily started event watcher).</p>
878	</dd>	1355	</dd>
879	<dt>ev_feed_fd_event (loop, int fd, int revents)</dt>	1356	<dt>ev_feed_fd_event (ev_loop *, int fd, int revents)</dt>
880	<dd>	1357	<dd>
881	<p>Feed an event on the given fd, as if a file descriptor backend detected	1358	<p>Feed an event on the given fd, as if a file descriptor backend detected
882	the given events it.</p>	1359	the given events it.</p>
883	</dd>	1360	</dd>
884	<dt>ev_feed_signal_event (loop, int signum)</dt>	1361	<dt>ev_feed_signal_event (ev_loop *loop, int signum)</dt>
885	<dd>	1362	<dd>
886	<p>Feed an event as if the given signal occured (loop must be the default loop!).</p>	1363	<p>Feed an event as if the given signal occured (<code>loop</code> must be the default
		1364	loop!).</p>
887	</dd>	1365	</dd>
888	</dl>	1366	</dl>
		1367
		1368
		1369
		1370
889		1371
890	</div>	1372	</div>
891	<h1 id="LIBEVENT_EMULATION">LIBEVENT EMULATION</h1><p><a href="#TOP" class="toplink">Top</a></p>	1373	<h1 id="LIBEVENT_EMULATION">LIBEVENT EMULATION</h1><p><a href="#TOP" class="toplink">Top</a></p>
892	<div id="LIBEVENT_EMULATION_CONTENT">	1374	<div id="LIBEVENT_EMULATION_CONTENT">
893	<p>Libev offers a compatibility emulation layer for libevent. It cannot	1375	<p>Libev offers a compatibility emulation layer for libevent. It cannot
…		…
908	</dl>	1390	</dl>
909		1391
910	</div>	1392	</div>
911	<h1 id="C_SUPPORT">C++ SUPPORT</h1><p><a href="#TOP" class="toplink">Top</a></p>	1393	<h1 id="C_SUPPORT">C++ SUPPORT</h1><p><a href="#TOP" class="toplink">Top</a></p>
912	<div id="C_SUPPORT_CONTENT">	1394	<div id="C_SUPPORT_CONTENT">
913	<p>TBD.</p>	1395	<p>Libev comes with some simplistic wrapper classes for C++ that mainly allow
		1396	you to use some convinience methods to start/stop watchers and also change
		1397	the callback model to a model using method callbacks on objects.</p>
		1398	<p>To use it,</p>
		1399	<pre> #include <ev++.h>
		1400
		1401	</pre>
		1402	<p>(it is not installed by default). This automatically includes <cite>ev.h</cite>
		1403	and puts all of its definitions (many of them macros) into the global
		1404	namespace. All C++ specific things are put into the <code>ev</code> namespace.</p>
		1405	<p>It should support all the same embedding options as <cite>ev.h</cite>, most notably
		1406	<code>EV_MULTIPLICITY</code>.</p>
		1407	<p>Here is a list of things available in the <code>ev</code> namespace:</p>
		1408	<dl>
		1409	<dt><code>ev::READ</code>, <code>ev::WRITE</code> etc.</dt>
		1410	<dd>
		1411	<p>These are just enum values with the same values as the <code>EV_READ</code> etc.
		1412	macros from <cite>ev.h</cite>.</p>
		1413	</dd>
		1414	<dt><code>ev::tstamp</code>, <code>ev::now</code></dt>
		1415	<dd>
		1416	<p>Aliases to the same types/functions as with the <code>ev_</code> prefix.</p>
		1417	</dd>
		1418	<dt><code>ev::io</code>, <code>ev::timer</code>, <code>ev::periodic</code>, <code>ev::idle</code>, <code>ev::sig</code> etc.</dt>
		1419	<dd>
		1420	<p>For each <code>ev_TYPE</code> watcher in <cite>ev.h</cite> there is a corresponding class of
		1421	the same name in the <code>ev</code> namespace, with the exception of <code>ev_signal</code>
		1422	which is called <code>ev::sig</code> to avoid clashes with the <code>signal</code> macro
		1423	defines by many implementations.</p>
		1424	<p>All of those classes have these methods:</p>
		1425	<p>
		1426	<dl>
		1427	<dt>ev::TYPE::TYPE (object , object::method )</dt>
		1428	<dt>ev::TYPE::TYPE (object , object::method , struct ev_loop *)</dt>
		1429	<dt>ev::TYPE::~TYPE</dt>
		1430	<dd>
		1431	<p>The constructor takes a pointer to an object and a method pointer to
		1432	the event handler callback to call in this class. The constructor calls
		1433	<code>ev_init</code> for you, which means you have to call the <code>set</code> method
		1434	before starting it. If you do not specify a loop then the constructor
		1435	automatically associates the default loop with this watcher.</p>
		1436	<p>The destructor automatically stops the watcher if it is active.</p>
		1437	</dd>
		1438	<dt>w->set (struct ev_loop *)</dt>
		1439	<dd>
		1440	<p>Associates a different <code>struct ev_loop</code> with this watcher. You can only
		1441	do this when the watcher is inactive (and not pending either).</p>
		1442	</dd>
		1443	<dt>w->set ([args])</dt>
		1444	<dd>
		1445	<p>Basically the same as <code>ev_TYPE_set</code>, with the same args. Must be
		1446	called at least once. Unlike the C counterpart, an active watcher gets
		1447	automatically stopped and restarted.</p>
		1448	</dd>
		1449	<dt>w->start ()</dt>
		1450	<dd>
		1451	<p>Starts the watcher. Note that there is no <code>loop</code> argument as the
		1452	constructor already takes the loop.</p>
		1453	</dd>
		1454	<dt>w->stop ()</dt>
		1455	<dd>
		1456	<p>Stops the watcher if it is active. Again, no <code>loop</code> argument.</p>
		1457	</dd>
		1458	<dt>w->again () <code>ev::timer</code>, <code>ev::periodic</code> only</dt>
		1459	<dd>
		1460	<p>For <code>ev::timer</code> and <code>ev::periodic</code>, this invokes the corresponding
		1461	<code>ev_TYPE_again</code> function.</p>
		1462	</dd>
		1463	<dt>w->sweep () <code>ev::embed</code> only</dt>
		1464	<dd>
		1465	<p>Invokes <code>ev_embed_sweep</code>.</p>
		1466	</dd>
		1467	</dl>
		1468	</p>
		1469	</dd>
		1470	</dl>
		1471	<p>Example: Define a class with an IO and idle watcher, start one of them in
		1472	the constructor.</p>
		1473	<pre> class myclass
		1474	{
		1475	ev_io io; void io_cb (ev::io &w, int revents);
		1476	ev_idle idle void idle_cb (ev::idle &w, int revents);
		1477
		1478	myclass ();
		1479	}
		1480
		1481	myclass::myclass (int fd)
		1482	: io (this, &myclass::io_cb),
		1483	idle (this, &myclass::idle_cb)
		1484	{
		1485	io.start (fd, ev::READ);
		1486	}
		1487
		1488	</pre>
		1489
		1490	</div>
		1491	<h1 id="EMBEDDING">EMBEDDING</h1><p><a href="#TOP" class="toplink">Top</a></p>
		1492	<div id="EMBEDDING_CONTENT">
		1493	<p>Libev can (and often is) directly embedded into host
		1494	applications. Examples of applications that embed it include the Deliantra
		1495	Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe)
		1496	and rxvt-unicode.</p>
		1497	<p>The goal is to enable you to just copy the neecssary files into your
		1498	source directory without having to change even a single line in them, so
		1499	you can easily upgrade by simply copying (or having a checked-out copy of
		1500	libev somewhere in your source tree).</p>
		1501
		1502	</div>
		1503	<h2 id="FILESETS">FILESETS</h2>
		1504	<div id="FILESETS_CONTENT">
		1505	<p>Depending on what features you need you need to include one or more sets of files
		1506	in your app.</p>
		1507
		1508	</div>
		1509	<h3 id="CORE_EVENT_LOOP">CORE EVENT LOOP</h3>
		1510	<div id="CORE_EVENT_LOOP_CONTENT">
		1511	<p>To include only the libev core (all the <code>ev_*</code> functions), with manual
		1512	configuration (no autoconf):</p>
		1513	<pre> #define EV_STANDALONE 1
		1514	#include "ev.c"
		1515
		1516	</pre>
		1517	<p>This will automatically include <cite>ev.h</cite>, too, and should be done in a
		1518	single C source file only to provide the function implementations. To use
		1519	it, do the same for <cite>ev.h</cite> in all files wishing to use this API (best
		1520	done by writing a wrapper around <cite>ev.h</cite> that you can include instead and
		1521	where you can put other configuration options):</p>
		1522	<pre> #define EV_STANDALONE 1
		1523	#include "ev.h"
		1524
		1525	</pre>
		1526	<p>Both header files and implementation files can be compiled with a C++
		1527	compiler (at least, thats a stated goal, and breakage will be treated
		1528	as a bug).</p>
		1529	<p>You need the following files in your source tree, or in a directory
		1530	in your include path (e.g. in libev/ when using -Ilibev):</p>
		1531	<pre> ev.h
		1532	ev.c
		1533	ev_vars.h
		1534	ev_wrap.h
		1535
		1536	ev_win32.c required on win32 platforms only
		1537
		1538	ev_select.c only when select backend is enabled (which is by default)
		1539	ev_poll.c only when poll backend is enabled (disabled by default)
		1540	ev_epoll.c only when the epoll backend is enabled (disabled by default)
		1541	ev_kqueue.c only when the kqueue backend is enabled (disabled by default)
		1542	ev_port.c only when the solaris port backend is enabled (disabled by default)
		1543
		1544	</pre>
		1545	<p><cite>ev.c</cite> includes the backend files directly when enabled, so you only need
		1546	to compile this single file.</p>
		1547
		1548	</div>
		1549	<h3 id="LIBEVENT_COMPATIBILITY_API">LIBEVENT COMPATIBILITY API</h3>
		1550	<div id="LIBEVENT_COMPATIBILITY_API_CONTENT">
		1551	<p>To include the libevent compatibility API, also include:</p>
		1552	<pre> #include "event.c"
		1553
		1554	</pre>
		1555	<p>in the file including <cite>ev.c</cite>, and:</p>
		1556	<pre> #include "event.h"
		1557
		1558	</pre>
		1559	<p>in the files that want to use the libevent API. This also includes <cite>ev.h</cite>.</p>
		1560	<p>You need the following additional files for this:</p>
		1561	<pre> event.h
		1562	event.c
		1563
		1564	</pre>
		1565
		1566	</div>
		1567	<h3 id="AUTOCONF_SUPPORT">AUTOCONF SUPPORT</h3>
		1568	<div id="AUTOCONF_SUPPORT_CONTENT">
		1569	<p>Instead of using <code>EV_STANDALONE=1</code> and providing your config in
		1570	whatever way you want, you can also <code>m4_include([libev.m4])</code> in your
		1571	<cite>configure.ac</cite> and leave <code>EV_STANDALONE</code> undefined. <cite>ev.c</cite> will then
		1572	include <cite>config.h</cite> and configure itself accordingly.</p>
		1573	<p>For this of course you need the m4 file:</p>
		1574	<pre> libev.m4
		1575
		1576	</pre>
		1577
		1578	</div>
		1579	<h2 id="PREPROCESSOR_SYMBOLS_MACROS">PREPROCESSOR SYMBOLS/MACROS</h2>
		1580	<div id="PREPROCESSOR_SYMBOLS_MACROS_CONTENT">
		1581	<p>Libev can be configured via a variety of preprocessor symbols you have to define
		1582	before including any of its files. The default is not to build for multiplicity
		1583	and only include the select backend.</p>
		1584	<dl>
		1585	<dt>EV_STANDALONE</dt>
		1586	<dd>
		1587	<p>Must always be <code>1</code> if you do not use autoconf configuration, which
		1588	keeps libev from including <cite>config.h</cite>, and it also defines dummy
		1589	implementations for some libevent functions (such as logging, which is not
		1590	supported). It will also not define any of the structs usually found in
		1591	<cite>event.h</cite> that are not directly supported by the libev core alone.</p>
		1592	</dd>
		1593	<dt>EV_USE_MONOTONIC</dt>
		1594	<dd>
		1595	<p>If defined to be <code>1</code>, libev will try to detect the availability of the
		1596	monotonic clock option at both compiletime and runtime. Otherwise no use
		1597	of the monotonic clock option will be attempted. If you enable this, you
		1598	usually have to link against librt or something similar. Enabling it when
		1599	the functionality isn't available is safe, though, althoguh you have
		1600	to make sure you link against any libraries where the <code>clock_gettime</code>
		1601	function is hiding in (often <cite>-lrt</cite>).</p>
		1602	</dd>
		1603	<dt>EV_USE_REALTIME</dt>
		1604	<dd>
		1605	<p>If defined to be <code>1</code>, libev will try to detect the availability of the
		1606	realtime clock option at compiletime (and assume its availability at
		1607	runtime if successful). Otherwise no use of the realtime clock option will
		1608	be attempted. This effectively replaces <code>gettimeofday</code> by <code>clock_get
		1609	(CLOCK_REALTIME, ...)</code> and will not normally affect correctness. See tzhe note about libraries
		1610	in the description of <code>EV_USE_MONOTONIC</code>, though.</p>
		1611	</dd>
		1612	<dt>EV_USE_SELECT</dt>
		1613	<dd>
		1614	<p>If undefined or defined to be <code>1</code>, libev will compile in support for the
		1615	<code>select</code>(2) backend. No attempt at autodetection will be done: if no
		1616	other method takes over, select will be it. Otherwise the select backend
		1617	will not be compiled in.</p>
		1618	</dd>
		1619	<dt>EV_SELECT_USE_FD_SET</dt>
		1620	<dd>
		1621	<p>If defined to <code>1</code>, then the select backend will use the system <code>fd_set</code>
		1622	structure. This is useful if libev doesn't compile due to a missing
		1623	<code>NFDBITS</code> or <code>fd_mask</code> definition or it misguesses the bitset layout on
		1624	exotic systems. This usually limits the range of file descriptors to some
		1625	low limit such as 1024 or might have other limitations (winsocket only
		1626	allows 64 sockets). The <code>FD_SETSIZE</code> macro, set before compilation, might
		1627	influence the size of the <code>fd_set</code> used.</p>
		1628	</dd>
		1629	<dt>EV_SELECT_IS_WINSOCKET</dt>
		1630	<dd>
		1631	<p>When defined to <code>1</code>, the select backend will assume that
		1632	select/socket/connect etc. don't understand file descriptors but
		1633	wants osf handles on win32 (this is the case when the select to
		1634	be used is the winsock select). This means that it will call
		1635	<code>_get_osfhandle</code> on the fd to convert it to an OS handle. Otherwise,
		1636	it is assumed that all these functions actually work on fds, even
		1637	on win32. Should not be defined on non-win32 platforms.</p>
		1638	</dd>
		1639	<dt>EV_USE_POLL</dt>
		1640	<dd>
		1641	<p>If defined to be <code>1</code>, libev will compile in support for the <code>poll</code>(2)
		1642	backend. Otherwise it will be enabled on non-win32 platforms. It
		1643	takes precedence over select.</p>
		1644	</dd>
		1645	<dt>EV_USE_EPOLL</dt>
		1646	<dd>
		1647	<p>If defined to be <code>1</code>, libev will compile in support for the Linux
		1648	<code>epoll</code>(7) backend. Its availability will be detected at runtime,
		1649	otherwise another method will be used as fallback. This is the
		1650	preferred backend for GNU/Linux systems.</p>
		1651	</dd>
		1652	<dt>EV_USE_KQUEUE</dt>
		1653	<dd>
		1654	<p>If defined to be <code>1</code>, libev will compile in support for the BSD style
		1655	<code>kqueue</code>(2) backend. Its actual availability will be detected at runtime,
		1656	otherwise another method will be used as fallback. This is the preferred
		1657	backend for BSD and BSD-like systems, although on most BSDs kqueue only
		1658	supports some types of fds correctly (the only platform we found that
		1659	supports ptys for example was NetBSD), so kqueue might be compiled in, but
		1660	not be used unless explicitly requested. The best way to use it is to find
		1661	out whether kqueue supports your type of fd properly and use an embedded
		1662	kqueue loop.</p>
		1663	</dd>
		1664	<dt>EV_USE_PORT</dt>
		1665	<dd>
		1666	<p>If defined to be <code>1</code>, libev will compile in support for the Solaris
		1667	10 port style backend. Its availability will be detected at runtime,
		1668	otherwise another method will be used as fallback. This is the preferred
		1669	backend for Solaris 10 systems.</p>
		1670	</dd>
		1671	<dt>EV_USE_DEVPOLL</dt>
		1672	<dd>
		1673	<p>reserved for future expansion, works like the USE symbols above.</p>
		1674	</dd>
		1675	<dt>EV_H</dt>
		1676	<dd>
		1677	<p>The name of the <cite>ev.h</cite> header file used to include it. The default if
		1678	undefined is <code><ev.h></code> in <cite>event.h</cite> and <code>"ev.h"</code> in <cite>ev.c</cite>. This
		1679	can be used to virtually rename the <cite>ev.h</cite> header file in case of conflicts.</p>
		1680	</dd>
		1681	<dt>EV_CONFIG_H</dt>
		1682	<dd>
		1683	<p>If <code>EV_STANDALONE</code> isn't <code>1</code>, this variable can be used to override
		1684	<cite>ev.c</cite>'s idea of where to find the <cite>config.h</cite> file, similarly to
		1685	<code>EV_H</code>, above.</p>
		1686	</dd>
		1687	<dt>EV_EVENT_H</dt>
		1688	<dd>
		1689	<p>Similarly to <code>EV_H</code>, this macro can be used to override <cite>event.c</cite>'s idea
		1690	of how the <cite>event.h</cite> header can be found.</p>
		1691	</dd>
		1692	<dt>EV_PROTOTYPES</dt>
		1693	<dd>
		1694	<p>If defined to be <code>0</code>, then <cite>ev.h</cite> will not define any function
		1695	prototypes, but still define all the structs and other symbols. This is
		1696	occasionally useful if you want to provide your own wrapper functions
		1697	around libev functions.</p>
		1698	</dd>
		1699	<dt>EV_MULTIPLICITY</dt>
		1700	<dd>
		1701	<p>If undefined or defined to <code>1</code>, then all event-loop-specific functions
		1702	will have the <code>struct ev_loop *</code> as first argument, and you can create
		1703	additional independent event loops. Otherwise there will be no support
		1704	for multiple event loops and there is no first event loop pointer
		1705	argument. Instead, all functions act on the single default loop.</p>
		1706	</dd>
		1707	<dt>EV_PERIODICS</dt>
		1708	<dd>
		1709	<p>If undefined or defined to be <code>1</code>, then periodic timers are supported,
		1710	otherwise not. This saves a few kb of code.</p>
		1711	</dd>
		1712	<dt>EV_COMMON</dt>
		1713	<dd>
		1714	<p>By default, all watchers have a <code>void *data</code> member. By redefining
		1715	this macro to a something else you can include more and other types of
		1716	members. You have to define it each time you include one of the files,
		1717	though, and it must be identical each time.</p>
		1718	<p>For example, the perl EV module uses something like this:</p>
		1719	<pre> #define EV_COMMON \
		1720	SV self; / contains this struct */ \
		1721	SV cb_sv, fh /* note no trailing ";" */
		1722
		1723	</pre>
		1724	</dd>
		1725	<dt>EV_CB_DECLARE (type)</dt>
		1726	<dt>EV_CB_INVOKE (watcher, revents)</dt>
		1727	<dt>ev_set_cb (ev, cb)</dt>
		1728	<dd>
		1729	<p>Can be used to change the callback member declaration in each watcher,
		1730	and the way callbacks are invoked and set. Must expand to a struct member
		1731	definition and a statement, respectively. See the <cite>ev.v</cite> header file for
		1732	their default definitions. One possible use for overriding these is to
		1733	avoid the <code>struct ev_loop *</code> as first argument in all cases, or to use
		1734	method calls instead of plain function calls in C++.</p>
		1735
		1736	</div>
		1737	<h2 id="EXAMPLES">EXAMPLES</h2>
		1738	<div id="EXAMPLES_CONTENT">
		1739	<p>For a real-world example of a program the includes libev
		1740	verbatim, you can have a look at the EV perl module
		1741	(<a href="http://software.schmorp.de/pkg/EV.html">http://software.schmorp.de/pkg/EV.html</a>). It has the libev files in
		1742	the <cite>libev/</cite> subdirectory and includes them in the <cite>EV/EVAPI.h</cite> (public
		1743	interface) and <cite>EV.xs</cite> (implementation) files. Only the <cite>EV.xs</cite> file
		1744	will be compiled. It is pretty complex because it provides its own header
		1745	file.</p>
		1746	<p>The usage in rxvt-unicode is simpler. It has a <cite>ev_cpp.h</cite> header file
		1747	that everybody includes and which overrides some autoconf choices:</p>
		1748	<pre> #define EV_USE_POLL 0
		1749	#define EV_MULTIPLICITY 0
		1750	#define EV_PERIODICS 0
		1751	#define EV_CONFIG_H <config.h>
		1752
		1753	#include "ev++.h"
		1754
		1755	</pre>
		1756	<p>And a <cite>ev_cpp.C</cite> implementation file that contains libev proper and is compiled:</p>
		1757	<pre> #include "ev_cpp.h"
		1758	#include "ev.c"
		1759
		1760
		1761
		1762
		1763	</pre>
		1764
		1765	</div>
		1766	<h1 id="COMPLEXITIES">COMPLEXITIES</h1><p><a href="#TOP" class="toplink">Top</a></p>
		1767	<div id="COMPLEXITIES_CONTENT">
		1768	<p>In this section the complexities of (many of) the algorithms used inside
		1769	libev will be explained. For complexity discussions about backends see the
		1770	documentation for <code>ev_default_init</code>.</p>
		1771	<p>
		1772	<dl>
		1773	<dt>Starting and stopping timer/periodic watchers: O(log skipped_other_timers)</dt>
		1774	<dt>Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)</dt>
		1775	<dt>Starting io/check/prepare/idle/signal/child watchers: O(1)</dt>
		1776	<dt>Stopping check/prepare/idle watchers: O(1)</dt>
		1777	<dt>Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % 16))</dt>
		1778	<dt>Finding the next timer per loop iteration: O(1)</dt>
		1779	<dt>Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)</dt>
		1780	<dt>Activating one watcher: O(1)</dt>
		1781	</dl>
		1782	</p>
		1783
		1784
		1785
		1786
914		1787
915	</div>	1788	</div>
916	<h1 id="AUTHOR">AUTHOR</h1><p><a href="#TOP" class="toplink">Top</a></p>	1789	<h1 id="AUTHOR">AUTHOR</h1><p><a href="#TOP" class="toplink">Top</a></p>
917	<div id="AUTHOR_CONTENT">	1790	<div id="AUTHOR_CONTENT">
918	<p>Marc Lehmann <libev@schmorp.de>.</p>	1791	<p>Marc Lehmann <libev@schmorp.de>.</p>
919		1792
920	</div>	1793	</div>
921	</div></body>	1794	</div></body>
922	</html>	1795	</html>

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Revision 1.47 by root, Mon Nov 26 10:20:43 2007 UTC