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4	<head>	4	<head>
5	<title>libev</title>	5	<title>libev</title>
6	<meta name="description" content="Pod documentation for libev" />	6	<meta name="description" content="Pod documentation for libev" />
7	<meta name="inputfile" content="<standard input>" />	7	<meta name="inputfile" content="<standard input>" />
8	<meta name="outputfile" content="<standard output>" />	8	<meta name="outputfile" content="<standard output>" />
9	<meta name="created" content="Sat Nov 24 08:13:46 2007" />	9	<meta name="created" content="Tue Nov 27 09:11:42 2007" />
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12	<body>	12	<body>
13	<div class="pod">	13	<div class="pod">
14	<!-- INDEX START -->	14	<!-- INDEX START -->
…		…
21	<li><a href="#CONVENTIONS">CONVENTIONS</a></li>	21	<li><a href="#CONVENTIONS">CONVENTIONS</a></li>
22	<li><a href="#TIME_REPRESENTATION">TIME REPRESENTATION</a></li>	22	<li><a href="#TIME_REPRESENTATION">TIME REPRESENTATION</a></li>
23	<li><a href="#GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</a></li>	23	<li><a href="#GLOBAL_FUNCTIONS">GLOBAL FUNCTIONS</a></li>
24	<li><a href="#FUNCTIONS_CONTROLLING_THE_EVENT_LOOP">FUNCTIONS CONTROLLING THE EVENT LOOP</a></li>	24	<li><a href="#FUNCTIONS_CONTROLLING_THE_EVENT_LOOP">FUNCTIONS CONTROLLING THE EVENT LOOP</a></li>
25	<li><a href="#ANATOMY_OF_A_WATCHER">ANATOMY OF A WATCHER</a>	25	<li><a href="#ANATOMY_OF_A_WATCHER">ANATOMY OF A WATCHER</a>
26	<ul><li><a href="#SUMMARY_OF_GENERIC_WATCHER_FUNCTIONS">SUMMARY OF GENERIC WATCHER FUNCTIONS</a></li>	26	<ul><li><a href="#GENERIC_WATCHER_FUNCTIONS">GENERIC WATCHER FUNCTIONS</a></li>
27	<li><a href="#ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH">ASSOCIATING CUSTOM DATA WITH A WATCHER</a></li>	27	<li><a href="#ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH">ASSOCIATING CUSTOM DATA WITH A WATCHER</a></li>
28	</ul>	28	</ul>
29	</li>	29	</li>
30	<li><a href="#WATCHER_TYPES">WATCHER TYPES</a>	30	<li><a href="#WATCHER_TYPES">WATCHER TYPES</a>
31	<ul><li><a href="#code_ev_io_code_is_this_file_descrip"><code>ev_io</code> - is this file descriptor readable or writable</a></li>	31	<ul><li><a href="#code_ev_io_code_is_this_file_descrip"><code>ev_io</code> - is this file descriptor readable or writable?</a></li>
32	<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>
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_periodic_code_to_cron_or_not"><code>ev_periodic</code> - to cron or not to cron?</a></li>
34	<li><a href="#code_ev_signal_code_signal_me_when_a"><code>ev_signal</code> - signal me when a signal gets signalled</a></li>	34	<li><a href="#code_ev_signal_code_signal_me_when_a"><code>ev_signal</code> - signal me when a signal gets signalled!</a></li>
35	<li><a href="#code_ev_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>
		36	<li><a href="#code_ev_stat_code_did_the_file_attri"><code>ev_stat</code> - did the file attributes just change?</a></li>
36	<li><a href="#code_ev_idle_code_when_you_ve_got_no"><code>ev_idle</code> - when you've got nothing better to do</a></li>	37	<li><a href="#code_ev_idle_code_when_you_ve_got_no"><code>ev_idle</code> - when you've got nothing better to do...</a></li>
37	<li><a href="#code_ev_prepare_code_and_code_ev_che"><code>ev_prepare</code> and <code>ev_check</code> - customise your event loop</a></li>	38	<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>	39	<li><a href="#code_ev_embed_code_when_one_backend_"><code>ev_embed</code> - when one backend isn't enough...</a></li>
39	</ul>	40	</ul>
40	</li>	41	</li>
41	<li><a href="#OTHER_FUNCTIONS">OTHER FUNCTIONS</a></li>	42	<li><a href="#OTHER_FUNCTIONS">OTHER FUNCTIONS</a></li>
42	<li><a href="#LIBEVENT_EMULATION">LIBEVENT EMULATION</a></li>	43	<li><a href="#LIBEVENT_EMULATION">LIBEVENT EMULATION</a></li>
43	<li><a href="#C_SUPPORT">C++ SUPPORT</a></li>	44	<li><a href="#C_SUPPORT">C++ SUPPORT</a></li>
		45	<li><a href="#EMBEDDING">EMBEDDING</a>
		46	<ul><li><a href="#FILESETS">FILESETS</a>
		47	<ul><li><a href="#CORE_EVENT_LOOP">CORE EVENT LOOP</a></li>
		48	<li><a href="#LIBEVENT_COMPATIBILITY_API">LIBEVENT COMPATIBILITY API</a></li>
		49	<li><a href="#AUTOCONF_SUPPORT">AUTOCONF SUPPORT</a></li>
		50	</ul>
		51	</li>
		52	<li><a href="#PREPROCESSOR_SYMBOLS_MACROS">PREPROCESSOR SYMBOLS/MACROS</a></li>
		53	<li><a href="#EXAMPLES">EXAMPLES</a></li>
		54	</ul>
		55	</li>
		56	<li><a href="#COMPLEXITIES">COMPLEXITIES</a></li>
44	<li><a href="#AUTHOR">AUTHOR</a>	57	<li><a href="#AUTHOR">AUTHOR</a>
45	</li>	58	</li>
46	</ul><hr />	59	</ul><hr />
47	<!-- INDEX END -->	60	<!-- INDEX END -->
48		61
…		…
364	</pre>	377	</pre>
365	</dd>	378	</dd>
366	<dt>ev_default_destroy ()</dt>	379	<dt>ev_default_destroy ()</dt>
367	<dd>	380	<dd>
368	<p>Destroys the default loop again (frees all memory and kernel state	381	<p>Destroys the default loop again (frees all memory and kernel state
369	etc.). This stops all registered event watchers (by not touching them in	382	etc.). None of the active event watchers will be stopped in the normal
370	any way whatsoever, although you cannot rely on this :).</p>	383	sense, so e.g. <code>ev_is_active</code> might still return true. It is your
		384	responsibility to either stop all watchers cleanly yoursef <i>before</i>
		385	calling this function, or cope with the fact afterwards (which is usually
		386	the easiest thing, youc na just ignore the watchers and/or <code>free ()</code> them
		387	for example).</p>
371	</dd>	388	</dd>
372	<dt>ev_loop_destroy (loop)</dt>	389	<dt>ev_loop_destroy (loop)</dt>
373	<dd>	390	<dd>
374	<p>Like <code>ev_default_destroy</code>, but destroys an event loop created by an	391	<p>Like <code>ev_default_destroy</code>, but destroys an event loop created by an
375	earlier call to <code>ev_loop_new</code>.</p>	392	earlier call to <code>ev_loop_new</code>.</p>
…		…
498		515
499	</pre>	516	</pre>
500	</dd>	517	</dd>
501	</dl>	518	</dl>
502		519
		520
		521
		522
		523
503	</div>	524	</div>
504	<h1 id="ANATOMY_OF_A_WATCHER">ANATOMY OF A WATCHER</h1><p><a href="#TOP" class="toplink">Top</a></p>	525	<h1 id="ANATOMY_OF_A_WATCHER">ANATOMY OF A WATCHER</h1><p><a href="#TOP" class="toplink">Top</a></p>
505	<div id="ANATOMY_OF_A_WATCHER_CONTENT">	526	<div id="ANATOMY_OF_A_WATCHER_CONTENT">
506	<p>A watcher is a structure that you create and register to record your	527	<p>A watcher is a structure that you create and register to record your
507	interest in some event. For instance, if you want to wait for STDIN to	528	interest in some event. For instance, if you want to wait for STDIN to
…		…
566	</dd>	587	</dd>
567	<dt><code>EV_CHILD</code></dt>	588	<dt><code>EV_CHILD</code></dt>
568	<dd>	589	<dd>
569	<p>The pid specified in the <code>ev_child</code> watcher has received a status change.</p>	590	<p>The pid specified in the <code>ev_child</code> watcher has received a status change.</p>
570	</dd>	591	</dd>
		592	<dt><code>EV_STAT</code></dt>
		593	<dd>
		594	<p>The path specified in the <code>ev_stat</code> watcher changed its attributes somehow.</p>
		595	</dd>
571	<dt><code>EV_IDLE</code></dt>	596	<dt><code>EV_IDLE</code></dt>
572	<dd>	597	<dd>
573	<p>The <code>ev_idle</code> watcher has determined that you have nothing better to do.</p>	598	<p>The <code>ev_idle</code> watcher has determined that you have nothing better to do.</p>
574	</dd>	599	</dd>
575	<dt><code>EV_PREPARE</code></dt>	600	<dt><code>EV_PREPARE</code></dt>
…		…
597	programs, though, so beware.</p>	622	programs, though, so beware.</p>
598	</dd>	623	</dd>
599	</dl>	624	</dl>
600		625
601	</div>	626	</div>
602	<h2 id="SUMMARY_OF_GENERIC_WATCHER_FUNCTIONS">SUMMARY OF GENERIC WATCHER FUNCTIONS</h2>	627	<h2 id="GENERIC_WATCHER_FUNCTIONS">GENERIC WATCHER FUNCTIONS</h2>
603	<div id="SUMMARY_OF_GENERIC_WATCHER_FUNCTIONS-2">	628	<div id="GENERIC_WATCHER_FUNCTIONS_CONTENT">
604	<p>In the following description, <code>TYPE</code> stands for the watcher type,	629	<p>In the following description, <code>TYPE</code> stands for the watcher type,
605	e.g. <code>timer</code> for <code>ev_timer</code> watchers and <code>io</code> for <code>ev_io</code> watchers.</p>	630	e.g. <code>timer</code> for <code>ev_timer</code> watchers and <code>io</code> for <code>ev_io</code> watchers.</p>
606	<dl>	631	<dl>
607	<dt><code>ev_init</code> (ev_TYPE *watcher, callback)</dt>	632	<dt><code>ev_init</code> (ev_TYPE *watcher, callback)</dt>
608	<dd>	633	<dd>
…		…
612	the type-specific <code>ev_TYPE_set</code> macro afterwards to initialise the	637	the type-specific <code>ev_TYPE_set</code> macro afterwards to initialise the
613	type-specific parts. For each type there is also a <code>ev_TYPE_init</code> macro	638	type-specific parts. For each type there is also a <code>ev_TYPE_init</code> macro
614	which rolls both calls into one.</p>	639	which rolls both calls into one.</p>
615	<p>You can reinitialise a watcher at any time as long as it has been stopped	640	<p>You can reinitialise a watcher at any time as long as it has been stopped
616	(or never started) and there are no pending events outstanding.</p>	641	(or never started) and there are no pending events outstanding.</p>
617	<p>The callbakc is always of type <code>void ()(ev_loop loop, ev_TYPE *watcher,	642	<p>The callback is always of type <code>void ()(ev_loop loop, ev_TYPE *watcher,
618	int revents)</code>.</p>	643	int revents)</code>.</p>
619	</dd>	644	</dd>
620	<dt><code>ev_TYPE_set</code> (ev_TYPE *, [args])</dt>	645	<dt><code>ev_TYPE_set</code> (ev_TYPE *, [args])</dt>
621	<dd>	646	<dd>
622	<p>This macro initialises the type-specific parts of a watcher. You need to	647	<p>This macro initialises the type-specific parts of a watcher. You need to
…		…
712		737
713	</div>	738	</div>
714	<h1 id="WATCHER_TYPES">WATCHER TYPES</h1><p><a href="#TOP" class="toplink">Top</a></p>	739	<h1 id="WATCHER_TYPES">WATCHER TYPES</h1><p><a href="#TOP" class="toplink">Top</a></p>
715	<div id="WATCHER_TYPES_CONTENT">	740	<div id="WATCHER_TYPES_CONTENT">
716	<p>This section describes each watcher in detail, but will not repeat	741	<p>This section describes each watcher in detail, but will not repeat
717	information given in the last section.</p>	742	information given in the last section. Any initialisation/set macros,
		743	functions and members specific to the watcher type are explained.</p>
		744	<p>Members are additionally marked with either <i>[read-only]</i>, meaning that,
		745	while the watcher is active, you can look at the member and expect some
		746	sensible content, but you must not modify it (you can modify it while the
		747	watcher is stopped to your hearts content), or <i>[read-write]</i>, which
		748	means you can expect it to have some sensible content while the watcher
		749	is active, but you can also modify it. Modifying it may not do something
		750	sensible or take immediate effect (or do anything at all), but libev will
		751	not crash or malfunction in any way.</p>
718		752
719		753
720		754
721		755
722		756
723	</div>	757	</div>
724	<h2 id="code_ev_io_code_is_this_file_descrip"><code>ev_io</code> - is this file descriptor readable or writable</h2>	758	<h2 id="code_ev_io_code_is_this_file_descrip"><code>ev_io</code> - is this file descriptor readable or writable?</h2>
725	<div id="code_ev_io_code_is_this_file_descrip-2">	759	<div id="code_ev_io_code_is_this_file_descrip-2">
726	<p>I/O watchers check whether a file descriptor is readable or writable	760	<p>I/O watchers check whether a file descriptor is readable or writable
727	in each iteration of the event loop (This behaviour is called	761	in each iteration of the event loop, or, more precisely, when reading
728	level-triggering because you keep receiving events as long as the	762	would not block the process and writing would at least be able to write
729	condition persists. Remember you can stop the watcher if you don't want to	763	some data. This behaviour is called level-triggering because you keep
730	act on the event and neither want to receive future events).</p>	764	receiving events as long as the condition persists. Remember you can stop
		765	the watcher if you don't want to act on the event and neither want to
		766	receive future events.</p>
731	<p>In general you can register as many read and/or write event watchers per	767	<p>In general you can register as many read and/or write event watchers per
732	fd as you want (as long as you don't confuse yourself). Setting all file	768	fd as you want (as long as you don't confuse yourself). Setting all file
733	descriptors to non-blocking mode is also usually a good idea (but not	769	descriptors to non-blocking mode is also usually a good idea (but not
734	required if you know what you are doing).</p>	770	required if you know what you are doing).</p>
735	<p>You have to be careful with dup'ed file descriptors, though. Some backends	771	<p>You have to be careful with dup'ed file descriptors, though. Some backends
736	(the linux epoll backend is a notable example) cannot handle dup'ed file	772	(the linux epoll backend is a notable example) cannot handle dup'ed file
737	descriptors correctly if you register interest in two or more fds pointing	773	descriptors correctly if you register interest in two or more fds pointing
738	to the same underlying file/socket etc. description (that is, they share	774	to the same underlying file/socket/etc. description (that is, they share
739	the same underlying "file open").</p>	775	the same underlying "file open").</p>
740	<p>If you must do this, then force the use of a known-to-be-good backend	776	<p>If you must do this, then force the use of a known-to-be-good backend
741	(at the time of this writing, this includes only <code>EVBACKEND_SELECT</code> and	777	(at the time of this writing, this includes only <code>EVBACKEND_SELECT</code> and
742	<code>EVBACKEND_POLL</code>).</p>	778	<code>EVBACKEND_POLL</code>).</p>
		779	<p>Another thing you have to watch out for is that it is quite easy to
		780	receive "spurious" readyness notifications, that is your callback might
		781	be called with <code>EV_READ</code> but a subsequent <code>read</code>(2) will actually block
		782	because there is no data. Not only are some backends known to create a
		783	lot of those (for example solaris ports), it is very easy to get into
		784	this situation even with a relatively standard program structure. Thus
		785	it is best to always use non-blocking I/O: An extra <code>read</code>(2) returning
		786	<code>EAGAIN</code> is far preferable to a program hanging until some data arrives.</p>
		787	<p>If you cannot run the fd in non-blocking mode (for example you should not
		788	play around with an Xlib connection), then you have to seperately re-test
		789	wether a file descriptor is really ready with a known-to-be good interface
		790	such as poll (fortunately in our Xlib example, Xlib already does this on
		791	its own, so its quite safe to use).</p>
743	<dl>	792	<dl>
744	<dt>ev_io_init (ev_io *, callback, int fd, int events)</dt>	793	<dt>ev_io_init (ev_io *, callback, int fd, int events)</dt>
745	<dt>ev_io_set (ev_io *, int fd, int events)</dt>	794	<dt>ev_io_set (ev_io *, int fd, int events)</dt>
746	<dd>	795	<dd>
747	<p>Configures an <code>ev_io</code> watcher. The fd is the file descriptor to rceeive	796	<p>Configures an <code>ev_io</code> watcher. The <code>fd</code> is the file descriptor to
748	events for and events is either <code>EV_READ</code>, <code>EV_WRITE</code> or <code>EV_READ \|	797	rceeive events for and events is either <code>EV_READ</code>, <code>EV_WRITE</code> or
749	EV_WRITE</code> to receive the given events.</p>	798	<code>EV_READ \| EV_WRITE</code> to receive the given events.</p>
750	<p>Please note that most of the more scalable backend mechanisms (for example	799	</dd>
751	epoll and solaris ports) can result in spurious readyness notifications	800	<dt>int fd [read-only]</dt>
752	for file descriptors, so you practically need to use non-blocking I/O (and	801	<dd>
753	treat callback invocation as hint only), or retest separately with a safe	802	<p>The file descriptor being watched.</p>
754	interface before doing I/O (XLib can do this), or force the use of either	803	</dd>
755	<code>EVBACKEND_SELECT</code> or <code>EVBACKEND_POLL</code>, which don't suffer from this	804	<dt>int events [read-only]</dt>
756	problem. Also note that it is quite easy to have your callback invoked	805	<dd>
757	when the readyness condition is no longer valid even when employing	806	<p>The events being watched.</p>
758	typical ways of handling events, so its a good idea to use non-blocking
759	I/O unconditionally.</p>
760	</dd>	807	</dd>
761	</dl>	808	</dl>
762	<p>Example: call <code>stdin_readable_cb</code> when STDIN_FILENO has become, well	809	<p>Example: call <code>stdin_readable_cb</code> when STDIN_FILENO has become, well
763	readable, but only once. Since it is likely line-buffered, you could	810	readable, but only once. Since it is likely line-buffered, you could
764	attempt to read a whole line in the callback:</p>	811	attempt to read a whole line in the callback:</p>
…		…
780		827
781		828
782	</pre>	829	</pre>
783		830
784	</div>	831	</div>
785	<h2 id="code_ev_timer_code_relative_and_opti"><code>ev_timer</code> - relative and optionally recurring timeouts</h2>	832	<h2 id="code_ev_timer_code_relative_and_opti"><code>ev_timer</code> - relative and optionally repeating timeouts</h2>
786	<div id="code_ev_timer_code_relative_and_opti-2">	833	<div id="code_ev_timer_code_relative_and_opti-2">
787	<p>Timer watchers are simple relative timers that generate an event after a	834	<p>Timer watchers are simple relative timers that generate an event after a
788	given time, and optionally repeating in regular intervals after that.</p>	835	given time, and optionally repeating in regular intervals after that.</p>
789	<p>The timers are based on real time, that is, if you register an event that	836	<p>The timers are based on real time, that is, if you register an event that
790	times out after an hour and you reset your system clock to last years	837	times out after an hour and you reset your system clock to last years
…		…
822	repeating. The exact semantics are:</p>	869	repeating. The exact semantics are:</p>
823	<p>If the timer is started but nonrepeating, stop it.</p>	870	<p>If the timer is started but nonrepeating, stop it.</p>
824	<p>If the timer is repeating, either start it if necessary (with the repeat	871	<p>If the timer is repeating, either start it if necessary (with the repeat
825	value), or reset the running timer to the repeat value.</p>	872	value), or reset the running timer to the repeat value.</p>
826	<p>This sounds a bit complicated, but here is a useful and typical	873	<p>This sounds a bit complicated, but here is a useful and typical
827	example: Imagine you have a tcp connection and you want a so-called idle	874	example: Imagine you have a tcp connection and you want a so-called
828	timeout, that is, you want to be called when there have been, say, 60	875	idle timeout, that is, you want to be called when there have been,
829	seconds of inactivity on the socket. The easiest way to do this is to	876	say, 60 seconds of inactivity on the socket. The easiest way to do
830	configure an <code>ev_timer</code> with after=repeat=60 and calling ev_timer_again each	877	this is to configure an <code>ev_timer</code> with <code>after</code>=<code>repeat</code>=<code>60</code> and calling
831	time you successfully read or write some data. If you go into an idle	878	<code>ev_timer_again</code> each time you successfully read or write some data. If
832	state where you do not expect data to travel on the socket, you can stop	879	you go into an idle state where you do not expect data to travel on the
833	the timer, and again will automatically restart it if need be.</p>	880	socket, you can stop the timer, and again will automatically restart it if
		881	need be.</p>
		882	<p>You can also ignore the <code>after</code> value and <code>ev_timer_start</code> altogether
		883	and only ever use the <code>repeat</code> value:</p>
		884	<pre> ev_timer_init (timer, callback, 0., 5.);
		885	ev_timer_again (loop, timer);
		886	...
		887	timer->again = 17.;
		888	ev_timer_again (loop, timer);
		889	...
		890	timer->again = 10.;
		891	ev_timer_again (loop, timer);
		892
		893	</pre>
		894	<p>This is more efficient then stopping/starting the timer eahc time you want
		895	to modify its timeout value.</p>
		896	</dd>
		897	<dt>ev_tstamp repeat [read-write]</dt>
		898	<dd>
		899	<p>The current <code>repeat</code> value. Will be used each time the watcher times out
		900	or <code>ev_timer_again</code> is called and determines the next timeout (if any),
		901	which is also when any modifications are taken into account.</p>
834	</dd>	902	</dd>
835	</dl>	903	</dl>
836	<p>Example: create a timer that fires after 60 seconds.</p>	904	<p>Example: create a timer that fires after 60 seconds.</p>
837	<pre> static void	905	<pre> static void
838	one_minute_cb (struct ev_loop loop, struct ev_timer w, int revents)	906	one_minute_cb (struct ev_loop loop, struct ev_timer w, int revents)
…		…
866		934
867		935
868	</pre>	936	</pre>
869		937
870	</div>	938	</div>
871	<h2 id="code_ev_periodic_code_to_cron_or_not"><code>ev_periodic</code> - to cron or not to cron</h2>	939	<h2 id="code_ev_periodic_code_to_cron_or_not"><code>ev_periodic</code> - to cron or not to cron?</h2>
872	<div id="code_ev_periodic_code_to_cron_or_not-2">	940	<div id="code_ev_periodic_code_to_cron_or_not-2">
873	<p>Periodic watchers are also timers of a kind, but they are very versatile	941	<p>Periodic watchers are also timers of a kind, but they are very versatile
874	(and unfortunately a bit complex).</p>	942	(and unfortunately a bit complex).</p>
875	<p>Unlike <code>ev_timer</code>'s, they are not based on real time (or relative time)	943	<p>Unlike <code>ev_timer</code>'s, they are not based on real time (or relative time)
876	but on wallclock time (absolute time). You can tell a periodic watcher	944	but on wallclock time (absolute time). You can tell a periodic watcher
877	to trigger "at" some specific point in time. For example, if you tell a	945	to trigger "at" some specific point in time. For example, if you tell a
878	periodic watcher to trigger in 10 seconds (by specifiying e.g. c<ev_now ()	946	periodic watcher to trigger in 10 seconds (by specifiying e.g. <code>ev_now ()
879	+ 10.>) and then reset your system clock to the last year, then it will	947	+ 10.</code>) and then reset your system clock to the last year, then it will
880	take a year to trigger the event (unlike an <code>ev_timer</code>, which would trigger	948	take a year to trigger the event (unlike an <code>ev_timer</code>, which would trigger
881	roughly 10 seconds later and of course not if you reset your system time	949	roughly 10 seconds later and of course not if you reset your system time
882	again).</p>	950	again).</p>
883	<p>They can also be used to implement vastly more complex timers, such as	951	<p>They can also be used to implement vastly more complex timers, such as
884	triggering an event on eahc midnight, local time.</p>	952	triggering an event on eahc midnight, local time.</p>
…		…
956	<p>Simply stops and restarts the periodic watcher again. This is only useful	1024	<p>Simply stops and restarts the periodic watcher again. This is only useful
957	when you changed some parameters or the reschedule callback would return	1025	when you changed some parameters or the reschedule callback would return
958	a different time than the last time it was called (e.g. in a crond like	1026	a different time than the last time it was called (e.g. in a crond like
959	program when the crontabs have changed).</p>	1027	program when the crontabs have changed).</p>
960	</dd>	1028	</dd>
		1029	<dt>ev_tstamp interval [read-write]</dt>
		1030	<dd>
		1031	<p>The current interval value. Can be modified any time, but changes only
		1032	take effect when the periodic timer fires or <code>ev_periodic_again</code> is being
		1033	called.</p>
		1034	</dd>
		1035	<dt>ev_tstamp (reschedule_cb)(struct ev_periodic w, ev_tstamp now) [read-write]</dt>
		1036	<dd>
		1037	<p>The current reschedule callback, or <code>0</code>, if this functionality is
		1038	switched off. Can be changed any time, but changes only take effect when
		1039	the periodic timer fires or <code>ev_periodic_again</code> is being called.</p>
		1040	</dd>
961	</dl>	1041	</dl>
962	<p>Example: call a callback every hour, or, more precisely, whenever the	1042	<p>Example: call a callback every hour, or, more precisely, whenever the
963	system clock is divisible by 3600. The callback invocation times have	1043	system clock is divisible by 3600. The callback invocation times have
964	potentially a lot of jittering, but good long-term stability.</p>	1044	potentially a lot of jittering, but good long-term stability.</p>
965	<pre> static void	1045	<pre> static void
…		…
995		1075
996		1076
997	</pre>	1077	</pre>
998		1078
999	</div>	1079	</div>
1000	<h2 id="code_ev_signal_code_signal_me_when_a"><code>ev_signal</code> - signal me when a signal gets signalled</h2>	1080	<h2 id="code_ev_signal_code_signal_me_when_a"><code>ev_signal</code> - signal me when a signal gets signalled!</h2>
1001	<div id="code_ev_signal_code_signal_me_when_a-2">	1081	<div id="code_ev_signal_code_signal_me_when_a-2">
1002	<p>Signal watchers will trigger an event when the process receives a specific	1082	<p>Signal watchers will trigger an event when the process receives a specific
1003	signal one or more times. Even though signals are very asynchronous, libev	1083	signal one or more times. Even though signals are very asynchronous, libev
1004	will try it's best to deliver signals synchronously, i.e. as part of the	1084	will try it's best to deliver signals synchronously, i.e. as part of the
1005	normal event processing, like any other event.</p>	1085	normal event processing, like any other event.</p>
…		…
1014	<dt>ev_signal_set (ev_signal *, int signum)</dt>	1094	<dt>ev_signal_set (ev_signal *, int signum)</dt>
1015	<dd>	1095	<dd>
1016	<p>Configures the watcher to trigger on the given signal number (usually one	1096	<p>Configures the watcher to trigger on the given signal number (usually one
1017	of the <code>SIGxxx</code> constants).</p>	1097	of the <code>SIGxxx</code> constants).</p>
1018	</dd>	1098	</dd>
		1099	<dt>int signum [read-only]</dt>
		1100	<dd>
		1101	<p>The signal the watcher watches out for.</p>
		1102	</dd>
1019	</dl>	1103	</dl>
1020		1104
1021		1105
1022		1106
1023		1107
1024		1108
1025	</div>	1109	</div>
1026	<h2 id="code_ev_child_code_wait_for_pid_stat"><code>ev_child</code> - wait for pid status changes</h2>	1110	<h2 id="code_ev_child_code_watch_out_for_pro"><code>ev_child</code> - watch out for process status changes</h2>
1027	<div id="code_ev_child_code_wait_for_pid_stat-2">	1111	<div id="code_ev_child_code_watch_out_for_pro-2">
1028	<p>Child watchers trigger when your process receives a SIGCHLD in response to	1112	<p>Child watchers trigger when your process receives a SIGCHLD in response to
1029	some child status changes (most typically when a child of yours dies).</p>	1113	some child status changes (most typically when a child of yours dies).</p>
1030	<dl>	1114	<dl>
1031	<dt>ev_child_init (ev_child *, callback, int pid)</dt>	1115	<dt>ev_child_init (ev_child *, callback, int pid)</dt>
1032	<dt>ev_child_set (ev_child *, int pid)</dt>	1116	<dt>ev_child_set (ev_child *, int pid)</dt>
…		…
1035	<i>any</i> process if <code>pid</code> is specified as <code>0</code>). The callback can look	1119	<i>any</i> process if <code>pid</code> is specified as <code>0</code>). The callback can look
1036	at the <code>rstatus</code> member of the <code>ev_child</code> watcher structure to see	1120	at the <code>rstatus</code> member of the <code>ev_child</code> watcher structure to see
1037	the status word (use the macros from <code>sys/wait.h</code> and see your systems	1121	the status word (use the macros from <code>sys/wait.h</code> and see your systems
1038	<code>waitpid</code> documentation). The <code>rpid</code> member contains the pid of the	1122	<code>waitpid</code> documentation). The <code>rpid</code> member contains the pid of the
1039	process causing the status change.</p>	1123	process causing the status change.</p>
		1124	</dd>
		1125	<dt>int pid [read-only]</dt>
		1126	<dd>
		1127	<p>The process id this watcher watches out for, or <code>0</code>, meaning any process id.</p>
		1128	</dd>
		1129	<dt>int rpid [read-write]</dt>
		1130	<dd>
		1131	<p>The process id that detected a status change.</p>
		1132	</dd>
		1133	<dt>int rstatus [read-write]</dt>
		1134	<dd>
		1135	<p>The process exit/trace status caused by <code>rpid</code> (see your systems
		1136	<code>waitpid</code> and <code>sys/wait.h</code> documentation for details).</p>
1040	</dd>	1137	</dd>
1041	</dl>	1138	</dl>
1042	<p>Example: try to exit cleanly on SIGINT and SIGTERM.</p>	1139	<p>Example: try to exit cleanly on SIGINT and SIGTERM.</p>
1043	<pre> static void	1140	<pre> static void
1044	sigint_cb (struct ev_loop loop, struct ev_signal w, int revents)	1141	sigint_cb (struct ev_loop loop, struct ev_signal w, int revents)
…		…
1054		1151
1055		1152
1056	</pre>	1153	</pre>
1057		1154
1058	</div>	1155	</div>
		1156	<h2 id="code_ev_stat_code_did_the_file_attri"><code>ev_stat</code> - did the file attributes just change?</h2>
		1157	<div id="code_ev_stat_code_did_the_file_attri-2">
		1158	<p>This watches a filesystem path for attribute changes. That is, it calls
		1159	<code>stat</code> regularly (or when the OS says it changed) and sees if it changed
		1160	compared to the last time, invoking the callback if it did.</p>
		1161	<p>The path does not need to exist: changing from "path exists" to "path does
		1162	not exist" is a status change like any other. The condition "path does
		1163	not exist" is signified by the <code>st_nlink</code> field being zero (which is
		1164	otherwise always forced to be at least one) and all the other fields of
		1165	the stat buffer having unspecified contents.</p>
		1166	<p>Since there is no standard to do this, the portable implementation simply
		1167	calls <code>stat (2)</code> regulalry on the path to see if it changed somehow. You
		1168	can specify a recommended polling interval for this case. If you specify
		1169	a polling interval of <code>0</code> (highly recommended!) then a <i>suitable,
		1170	unspecified default</i> value will be used (which you can expect to be around
		1171	five seconds, although this might change dynamically). Libev will also
		1172	impose a minimum interval which is currently around <code>0.1</code>, but thats
		1173	usually overkill.</p>
		1174	<p>This watcher type is not meant for massive numbers of stat watchers,
		1175	as even with OS-supported change notifications, this can be
		1176	resource-intensive.</p>
		1177	<p>At the time of this writing, no specific OS backends are implemented, but
		1178	if demand increases, at least a kqueue and inotify backend will be added.</p>
		1179	<dl>
		1180	<dt>ev_stat_init (ev_stat , callback, const char path, ev_tstamp interval)</dt>
		1181	<dt>ev_stat_set (ev_stat , const char path, ev_tstamp interval)</dt>
		1182	<dd>
		1183	<p>Configures the watcher to wait for status changes of the given
		1184	<code>path</code>. The <code>interval</code> is a hint on how quickly a change is expected to
		1185	be detected and should normally be specified as <code>0</code> to let libev choose
		1186	a suitable value. The memory pointed to by <code>path</code> must point to the same
		1187	path for as long as the watcher is active.</p>
		1188	<p>The callback will be receive <code>EV_STAT</code> when a change was detected,
		1189	relative to the attributes at the time the watcher was started (or the
		1190	last change was detected).</p>
		1191	</dd>
		1192	<dt>ev_stat_stat (ev_stat *)</dt>
		1193	<dd>
		1194	<p>Updates the stat buffer immediately with new values. If you change the
		1195	watched path in your callback, you could call this fucntion to avoid
		1196	detecting this change (while introducing a race condition). Can also be
		1197	useful simply to find out the new values.</p>
		1198	</dd>
		1199	<dt>ev_statdata attr [read-only]</dt>
		1200	<dd>
		1201	<p>The most-recently detected attributes of the file. Although the type is of
		1202	<code>ev_statdata</code>, this is usually the (or one of the) <code>struct stat</code> types
		1203	suitable for your system. If the <code>st_nlink</code> member is <code>0</code>, then there
		1204	was some error while <code>stat</code>ing the file.</p>
		1205	</dd>
		1206	<dt>ev_statdata prev [read-only]</dt>
		1207	<dd>
		1208	<p>The previous attributes of the file. The callback gets invoked whenever
		1209	<code>prev</code> != <code>attr</code>.</p>
		1210	</dd>
		1211	<dt>ev_tstamp interval [read-only]</dt>
		1212	<dd>
		1213	<p>The specified interval.</p>
		1214	</dd>
		1215	<dt>const char *path [read-only]</dt>
		1216	<dd>
		1217	<p>The filesystem path that is being watched.</p>
		1218	</dd>
		1219	</dl>
		1220	<p>Example: Watch <code>/etc/passwd</code> for attribute changes.</p>
		1221	<pre> static void
		1222	passwd_cb (struct ev_loop loop, ev_stat w, int revents)
		1223	{
		1224	/* /etc/passwd changed in some way */
		1225	if (w->attr.st_nlink)
		1226	{
		1227	printf ("passwd current size %ld\n", (long)w->attr.st_size);
		1228	printf ("passwd current atime %ld\n", (long)w->attr.st_mtime);
		1229	printf ("passwd current mtime %ld\n", (long)w->attr.st_mtime);
		1230	}
		1231	else
		1232	/* you shalt not abuse printf for puts */
		1233	puts ("wow, /etc/passwd is not there, expect problems. "
		1234	"if this is windows, they already arrived\n");
		1235	}
		1236
		1237	...
		1238	ev_stat passwd;
		1239
		1240	ev_stat_init (&passwd, passwd_cb, "/etc/passwd");
		1241	ev_stat_start (loop, &passwd);
		1242
		1243
		1244
		1245
		1246	</pre>
		1247
		1248	</div>
1059	<h2 id="code_ev_idle_code_when_you_ve_got_no"><code>ev_idle</code> - when you've got nothing better to do</h2>	1249	<h2 id="code_ev_idle_code_when_you_ve_got_no"><code>ev_idle</code> - when you've got nothing better to do...</h2>
1060	<div id="code_ev_idle_code_when_you_ve_got_no-2">	1250	<div id="code_ev_idle_code_when_you_ve_got_no-2">
1061	<p>Idle watchers trigger events when there are no other events are pending	1251	<p>Idle watchers trigger events when there are no other events are pending
1062	(prepare, check and other idle watchers do not count). That is, as long	1252	(prepare, check and other idle watchers do not count). That is, as long
1063	as your process is busy handling sockets or timeouts (or even signals,	1253	as your process is busy handling sockets or timeouts (or even signals,
1064	imagine) it will not be triggered. But when your process is idle all idle	1254	imagine) it will not be triggered. But when your process is idle all idle
…		…
1097		1287
1098		1288
1099	</pre>	1289	</pre>
1100		1290
1101	</div>	1291	</div>
1102	<h2 id="code_ev_prepare_code_and_code_ev_che"><code>ev_prepare</code> and <code>ev_check</code> - customise your event loop</h2>	1292	<h2 id="code_ev_prepare_code_and_code_ev_che"><code>ev_prepare</code> and <code>ev_check</code> - customise your event loop!</h2>
1103	<div id="code_ev_prepare_code_and_code_ev_che-2">	1293	<div id="code_ev_prepare_code_and_code_ev_che-2">
1104	<p>Prepare and check watchers are usually (but not always) used in tandem:	1294	<p>Prepare and check watchers are usually (but not always) used in tandem:
1105	prepare watchers get invoked before the process blocks and check watchers	1295	prepare watchers get invoked before the process blocks and check watchers
1106	afterwards.</p>	1296	afterwards.</p>
		1297	<p>You <i>must not</i> call <code>ev_loop</code> or similar functions that enter
		1298	the current event loop from either <code>ev_prepare</code> or <code>ev_check</code>
		1299	watchers. Other loops than the current one are fine, however. The
		1300	rationale behind this is that you do not need to check for recursion in
		1301	those watchers, i.e. the sequence will always be <code>ev_prepare</code>, blocking,
		1302	<code>ev_check</code> so if you have one watcher of each kind they will always be
		1303	called in pairs bracketing the blocking call.</p>
1107	<p>Their main purpose is to integrate other event mechanisms into libev and	1304	<p>Their main purpose is to integrate other event mechanisms into libev and
1108	their use is somewhat advanced. This could be used, for example, to track	1305	their use is somewhat advanced. This could be used, for example, to track
1109	variable changes, implement your own watchers, integrate net-snmp or a	1306	variable changes, implement your own watchers, integrate net-snmp or a
1110	coroutine library and lots more.</p>	1307	coroutine library and lots more. They are also occasionally useful if
		1308	you cache some data and want to flush it before blocking (for example,
		1309	in X programs you might want to do an <code>XFlush ()</code> in an <code>ev_prepare</code>
		1310	watcher).</p>
1111	<p>This is done by examining in each prepare call which file descriptors need	1311	<p>This is done by examining in each prepare call which file descriptors need
1112	to be watched by the other library, registering <code>ev_io</code> watchers for	1312	to be watched by the other library, registering <code>ev_io</code> watchers for
1113	them and starting an <code>ev_timer</code> watcher for any timeouts (many libraries	1313	them and starting an <code>ev_timer</code> watcher for any timeouts (many libraries
1114	provide just this functionality). Then, in the check watcher you check for	1314	provide just this functionality). Then, in the check watcher you check for
1115	any events that occured (by checking the pending status of all watchers	1315	any events that occured (by checking the pending status of all watchers
…		…
1131	<p>Initialises and configures the prepare or check watcher - they have no	1331	<p>Initialises and configures the prepare or check watcher - they have no
1132	parameters of any kind. There are <code>ev_prepare_set</code> and <code>ev_check_set</code>	1332	parameters of any kind. There are <code>ev_prepare_set</code> and <code>ev_check_set</code>
1133	macros, but using them is utterly, utterly and completely pointless.</p>	1333	macros, but using them is utterly, utterly and completely pointless.</p>
1134	</dd>	1334	</dd>
1135	</dl>	1335	</dl>
1136	<p>Example: TODO.</p>	1336	<p>Example: To include a library such as adns, you would add IO watchers
		1337	and a timeout watcher in a prepare handler, as required by libadns, and
		1338	in a check watcher, destroy them and call into libadns. What follows is
		1339	pseudo-code only of course:</p>
		1340	<pre> static ev_io iow [nfd];
		1341	static ev_timer tw;
1137		1342
		1343	static void
		1344	io_cb (ev_loop loop, ev_io w, int revents)
		1345	{
		1346	// set the relevant poll flags
		1347	// could also call adns_processreadable etc. here
		1348	struct pollfd fd = (struct pollfd )w->data;
		1349	if (revents & EV_READ ) fd->revents \|= fd->events & POLLIN;
		1350	if (revents & EV_WRITE) fd->revents \|= fd->events & POLLOUT;
		1351	}
1138		1352
		1353	// create io watchers for each fd and a timer before blocking
		1354	static void
		1355	adns_prepare_cb (ev_loop loop, ev_prepare w, int revents)
		1356	{
		1357	int timeout = 3600000;truct pollfd fds [nfd];
		1358	// actual code will need to loop here and realloc etc.
		1359	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));
1139		1360
		1361	/* the callback is illegal, but won't be called as we stop during check */
		1362	ev_timer_init (&tw, 0, timeout * 1e-3);
		1363	ev_timer_start (loop, &tw);
1140		1364
		1365	// create on ev_io per pollfd
		1366	for (int i = 0; i < nfd; ++i)
		1367	{
		1368	ev_io_init (iow + i, io_cb, fds [i].fd,
		1369	((fds [i].events & POLLIN ? EV_READ : 0)
		1370	\| (fds [i].events & POLLOUT ? EV_WRITE : 0)));
1141		1371
		1372	fds [i].revents = 0;
		1373	iow [i].data = fds + i;
		1374	ev_io_start (loop, iow + i);
		1375	}
		1376	}
		1377
		1378	// stop all watchers after blocking
		1379	static void
		1380	adns_check_cb (ev_loop loop, ev_check w, int revents)
		1381	{
		1382	ev_timer_stop (loop, &tw);
		1383
		1384	for (int i = 0; i < nfd; ++i)
		1385	ev_io_stop (loop, iow + i);
		1386
		1387	adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));
		1388	}
		1389
		1390
		1391
		1392
		1393	</pre>
		1394
1142	</div>	1395	</div>
1143	<h2 id="code_ev_embed_code_when_one_backend_"><code>ev_embed</code> - when one backend isn't enough</h2>	1396	<h2 id="code_ev_embed_code_when_one_backend_"><code>ev_embed</code> - when one backend isn't enough...</h2>
1144	<div id="code_ev_embed_code_when_one_backend_-2">	1397	<div id="code_ev_embed_code_when_one_backend_-2">
1145	<p>This is a rather advanced watcher type that lets you embed one event loop	1398	<p>This is a rather advanced watcher type that lets you embed one event loop
1146	into another (currently only <code>ev_io</code> events are supported in the embedded	1399	into another (currently only <code>ev_io</code> events are supported in the embedded
1147	loop, other types of watchers might be handled in a delayed or incorrect	1400	loop, other types of watchers might be handled in a delayed or incorrect
1148	fashion and must not be used).</p>	1401	fashion and must not be used).</p>
…		…
1216	<dd>	1469	<dd>
1217	<p>Make a single, non-blocking sweep over the embedded loop. This works	1470	<p>Make a single, non-blocking sweep over the embedded loop. This works
1218	similarly to <code>ev_loop (embedded_loop, EVLOOP_NONBLOCK)</code>, but in the most	1471	similarly to <code>ev_loop (embedded_loop, EVLOOP_NONBLOCK)</code>, but in the most
1219	apropriate way for embedded loops.</p>	1472	apropriate way for embedded loops.</p>
1220	</dd>	1473	</dd>
		1474	<dt>struct ev_loop *loop [read-only]</dt>
		1475	<dd>
		1476	<p>The embedded event loop.</p>
		1477	</dd>
1221	</dl>	1478	</dl>
1222		1479
1223		1480
1224		1481
1225		1482
…		…
1302	</dl>	1559	</dl>
1303		1560
1304	</div>	1561	</div>
1305	<h1 id="C_SUPPORT">C++ SUPPORT</h1><p><a href="#TOP" class="toplink">Top</a></p>	1562	<h1 id="C_SUPPORT">C++ SUPPORT</h1><p><a href="#TOP" class="toplink">Top</a></p>
1306	<div id="C_SUPPORT_CONTENT">	1563	<div id="C_SUPPORT_CONTENT">
1307	<p>TBD.</p>	1564	<p>Libev comes with some simplistic wrapper classes for C++ that mainly allow
		1565	you to use some convinience methods to start/stop watchers and also change
		1566	the callback model to a model using method callbacks on objects.</p>
		1567	<p>To use it,</p>
		1568	<pre> #include <ev++.h>
		1569
		1570	</pre>
		1571	<p>(it is not installed by default). This automatically includes <cite>ev.h</cite>
		1572	and puts all of its definitions (many of them macros) into the global
		1573	namespace. All C++ specific things are put into the <code>ev</code> namespace.</p>
		1574	<p>It should support all the same embedding options as <cite>ev.h</cite>, most notably
		1575	<code>EV_MULTIPLICITY</code>.</p>
		1576	<p>Here is a list of things available in the <code>ev</code> namespace:</p>
		1577	<dl>
		1578	<dt><code>ev::READ</code>, <code>ev::WRITE</code> etc.</dt>
		1579	<dd>
		1580	<p>These are just enum values with the same values as the <code>EV_READ</code> etc.
		1581	macros from <cite>ev.h</cite>.</p>
		1582	</dd>
		1583	<dt><code>ev::tstamp</code>, <code>ev::now</code></dt>
		1584	<dd>
		1585	<p>Aliases to the same types/functions as with the <code>ev_</code> prefix.</p>
		1586	</dd>
		1587	<dt><code>ev::io</code>, <code>ev::timer</code>, <code>ev::periodic</code>, <code>ev::idle</code>, <code>ev::sig</code> etc.</dt>
		1588	<dd>
		1589	<p>For each <code>ev_TYPE</code> watcher in <cite>ev.h</cite> there is a corresponding class of
		1590	the same name in the <code>ev</code> namespace, with the exception of <code>ev_signal</code>
		1591	which is called <code>ev::sig</code> to avoid clashes with the <code>signal</code> macro
		1592	defines by many implementations.</p>
		1593	<p>All of those classes have these methods:</p>
		1594	<p>
		1595	<dl>
		1596	<dt>ev::TYPE::TYPE (object , object::method )</dt>
		1597	<dt>ev::TYPE::TYPE (object , object::method , struct ev_loop *)</dt>
		1598	<dt>ev::TYPE::~TYPE</dt>
		1599	<dd>
		1600	<p>The constructor takes a pointer to an object and a method pointer to
		1601	the event handler callback to call in this class. The constructor calls
		1602	<code>ev_init</code> for you, which means you have to call the <code>set</code> method
		1603	before starting it. If you do not specify a loop then the constructor
		1604	automatically associates the default loop with this watcher.</p>
		1605	<p>The destructor automatically stops the watcher if it is active.</p>
		1606	</dd>
		1607	<dt>w->set (struct ev_loop *)</dt>
		1608	<dd>
		1609	<p>Associates a different <code>struct ev_loop</code> with this watcher. You can only
		1610	do this when the watcher is inactive (and not pending either).</p>
		1611	</dd>
		1612	<dt>w->set ([args])</dt>
		1613	<dd>
		1614	<p>Basically the same as <code>ev_TYPE_set</code>, with the same args. Must be
		1615	called at least once. Unlike the C counterpart, an active watcher gets
		1616	automatically stopped and restarted.</p>
		1617	</dd>
		1618	<dt>w->start ()</dt>
		1619	<dd>
		1620	<p>Starts the watcher. Note that there is no <code>loop</code> argument as the
		1621	constructor already takes the loop.</p>
		1622	</dd>
		1623	<dt>w->stop ()</dt>
		1624	<dd>
		1625	<p>Stops the watcher if it is active. Again, no <code>loop</code> argument.</p>
		1626	</dd>
		1627	<dt>w->again () <code>ev::timer</code>, <code>ev::periodic</code> only</dt>
		1628	<dd>
		1629	<p>For <code>ev::timer</code> and <code>ev::periodic</code>, this invokes the corresponding
		1630	<code>ev_TYPE_again</code> function.</p>
		1631	</dd>
		1632	<dt>w->sweep () <code>ev::embed</code> only</dt>
		1633	<dd>
		1634	<p>Invokes <code>ev_embed_sweep</code>.</p>
		1635	</dd>
		1636	</dl>
		1637	</p>
		1638	</dd>
		1639	</dl>
		1640	<p>Example: Define a class with an IO and idle watcher, start one of them in
		1641	the constructor.</p>
		1642	<pre> class myclass
		1643	{
		1644	ev_io io; void io_cb (ev::io &w, int revents);
		1645	ev_idle idle void idle_cb (ev::idle &w, int revents);
		1646
		1647	myclass ();
		1648	}
		1649
		1650	myclass::myclass (int fd)
		1651	: io (this, &myclass::io_cb),
		1652	idle (this, &myclass::idle_cb)
		1653	{
		1654	io.start (fd, ev::READ);
		1655	}
		1656
		1657	</pre>
		1658
		1659	</div>
		1660	<h1 id="EMBEDDING">EMBEDDING</h1><p><a href="#TOP" class="toplink">Top</a></p>
		1661	<div id="EMBEDDING_CONTENT">
		1662	<p>Libev can (and often is) directly embedded into host
		1663	applications. Examples of applications that embed it include the Deliantra
		1664	Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe)
		1665	and rxvt-unicode.</p>
		1666	<p>The goal is to enable you to just copy the neecssary files into your
		1667	source directory without having to change even a single line in them, so
		1668	you can easily upgrade by simply copying (or having a checked-out copy of
		1669	libev somewhere in your source tree).</p>
		1670
		1671	</div>
		1672	<h2 id="FILESETS">FILESETS</h2>
		1673	<div id="FILESETS_CONTENT">
		1674	<p>Depending on what features you need you need to include one or more sets of files
		1675	in your app.</p>
		1676
		1677	</div>
		1678	<h3 id="CORE_EVENT_LOOP">CORE EVENT LOOP</h3>
		1679	<div id="CORE_EVENT_LOOP_CONTENT">
		1680	<p>To include only the libev core (all the <code>ev_*</code> functions), with manual
		1681	configuration (no autoconf):</p>
		1682	<pre> #define EV_STANDALONE 1
		1683	#include "ev.c"
		1684
		1685	</pre>
		1686	<p>This will automatically include <cite>ev.h</cite>, too, and should be done in a
		1687	single C source file only to provide the function implementations. To use
		1688	it, do the same for <cite>ev.h</cite> in all files wishing to use this API (best
		1689	done by writing a wrapper around <cite>ev.h</cite> that you can include instead and
		1690	where you can put other configuration options):</p>
		1691	<pre> #define EV_STANDALONE 1
		1692	#include "ev.h"
		1693
		1694	</pre>
		1695	<p>Both header files and implementation files can be compiled with a C++
		1696	compiler (at least, thats a stated goal, and breakage will be treated
		1697	as a bug).</p>
		1698	<p>You need the following files in your source tree, or in a directory
		1699	in your include path (e.g. in libev/ when using -Ilibev):</p>
		1700	<pre> ev.h
		1701	ev.c
		1702	ev_vars.h
		1703	ev_wrap.h
		1704
		1705	ev_win32.c required on win32 platforms only
		1706
		1707	ev_select.c only when select backend is enabled (which is by default)
		1708	ev_poll.c only when poll backend is enabled (disabled by default)
		1709	ev_epoll.c only when the epoll backend is enabled (disabled by default)
		1710	ev_kqueue.c only when the kqueue backend is enabled (disabled by default)
		1711	ev_port.c only when the solaris port backend is enabled (disabled by default)
		1712
		1713	</pre>
		1714	<p><cite>ev.c</cite> includes the backend files directly when enabled, so you only need
		1715	to compile this single file.</p>
		1716
		1717	</div>
		1718	<h3 id="LIBEVENT_COMPATIBILITY_API">LIBEVENT COMPATIBILITY API</h3>
		1719	<div id="LIBEVENT_COMPATIBILITY_API_CONTENT">
		1720	<p>To include the libevent compatibility API, also include:</p>
		1721	<pre> #include "event.c"
		1722
		1723	</pre>
		1724	<p>in the file including <cite>ev.c</cite>, and:</p>
		1725	<pre> #include "event.h"
		1726
		1727	</pre>
		1728	<p>in the files that want to use the libevent API. This also includes <cite>ev.h</cite>.</p>
		1729	<p>You need the following additional files for this:</p>
		1730	<pre> event.h
		1731	event.c
		1732
		1733	</pre>
		1734
		1735	</div>
		1736	<h3 id="AUTOCONF_SUPPORT">AUTOCONF SUPPORT</h3>
		1737	<div id="AUTOCONF_SUPPORT_CONTENT">
		1738	<p>Instead of using <code>EV_STANDALONE=1</code> and providing your config in
		1739	whatever way you want, you can also <code>m4_include([libev.m4])</code> in your
		1740	<cite>configure.ac</cite> and leave <code>EV_STANDALONE</code> undefined. <cite>ev.c</cite> will then
		1741	include <cite>config.h</cite> and configure itself accordingly.</p>
		1742	<p>For this of course you need the m4 file:</p>
		1743	<pre> libev.m4
		1744
		1745	</pre>
		1746
		1747	</div>
		1748	<h2 id="PREPROCESSOR_SYMBOLS_MACROS">PREPROCESSOR SYMBOLS/MACROS</h2>
		1749	<div id="PREPROCESSOR_SYMBOLS_MACROS_CONTENT">
		1750	<p>Libev can be configured via a variety of preprocessor symbols you have to define
		1751	before including any of its files. The default is not to build for multiplicity
		1752	and only include the select backend.</p>
		1753	<dl>
		1754	<dt>EV_STANDALONE</dt>
		1755	<dd>
		1756	<p>Must always be <code>1</code> if you do not use autoconf configuration, which
		1757	keeps libev from including <cite>config.h</cite>, and it also defines dummy
		1758	implementations for some libevent functions (such as logging, which is not
		1759	supported). It will also not define any of the structs usually found in
		1760	<cite>event.h</cite> that are not directly supported by the libev core alone.</p>
		1761	</dd>
		1762	<dt>EV_USE_MONOTONIC</dt>
		1763	<dd>
		1764	<p>If defined to be <code>1</code>, libev will try to detect the availability of the
		1765	monotonic clock option at both compiletime and runtime. Otherwise no use
		1766	of the monotonic clock option will be attempted. If you enable this, you
		1767	usually have to link against librt or something similar. Enabling it when
		1768	the functionality isn't available is safe, though, althoguh you have
		1769	to make sure you link against any libraries where the <code>clock_gettime</code>
		1770	function is hiding in (often <cite>-lrt</cite>).</p>
		1771	</dd>
		1772	<dt>EV_USE_REALTIME</dt>
		1773	<dd>
		1774	<p>If defined to be <code>1</code>, libev will try to detect the availability of the
		1775	realtime clock option at compiletime (and assume its availability at
		1776	runtime if successful). Otherwise no use of the realtime clock option will
		1777	be attempted. This effectively replaces <code>gettimeofday</code> by <code>clock_get
		1778	(CLOCK_REALTIME, ...)</code> and will not normally affect correctness. See tzhe note about libraries
		1779	in the description of <code>EV_USE_MONOTONIC</code>, though.</p>
		1780	</dd>
		1781	<dt>EV_USE_SELECT</dt>
		1782	<dd>
		1783	<p>If undefined or defined to be <code>1</code>, libev will compile in support for the
		1784	<code>select</code>(2) backend. No attempt at autodetection will be done: if no
		1785	other method takes over, select will be it. Otherwise the select backend
		1786	will not be compiled in.</p>
		1787	</dd>
		1788	<dt>EV_SELECT_USE_FD_SET</dt>
		1789	<dd>
		1790	<p>If defined to <code>1</code>, then the select backend will use the system <code>fd_set</code>
		1791	structure. This is useful if libev doesn't compile due to a missing
		1792	<code>NFDBITS</code> or <code>fd_mask</code> definition or it misguesses the bitset layout on
		1793	exotic systems. This usually limits the range of file descriptors to some
		1794	low limit such as 1024 or might have other limitations (winsocket only
		1795	allows 64 sockets). The <code>FD_SETSIZE</code> macro, set before compilation, might
		1796	influence the size of the <code>fd_set</code> used.</p>
		1797	</dd>
		1798	<dt>EV_SELECT_IS_WINSOCKET</dt>
		1799	<dd>
		1800	<p>When defined to <code>1</code>, the select backend will assume that
		1801	select/socket/connect etc. don't understand file descriptors but
		1802	wants osf handles on win32 (this is the case when the select to
		1803	be used is the winsock select). This means that it will call
		1804	<code>_get_osfhandle</code> on the fd to convert it to an OS handle. Otherwise,
		1805	it is assumed that all these functions actually work on fds, even
		1806	on win32. Should not be defined on non-win32 platforms.</p>
		1807	</dd>
		1808	<dt>EV_USE_POLL</dt>
		1809	<dd>
		1810	<p>If defined to be <code>1</code>, libev will compile in support for the <code>poll</code>(2)
		1811	backend. Otherwise it will be enabled on non-win32 platforms. It
		1812	takes precedence over select.</p>
		1813	</dd>
		1814	<dt>EV_USE_EPOLL</dt>
		1815	<dd>
		1816	<p>If defined to be <code>1</code>, libev will compile in support for the Linux
		1817	<code>epoll</code>(7) backend. Its availability will be detected at runtime,
		1818	otherwise another method will be used as fallback. This is the
		1819	preferred backend for GNU/Linux systems.</p>
		1820	</dd>
		1821	<dt>EV_USE_KQUEUE</dt>
		1822	<dd>
		1823	<p>If defined to be <code>1</code>, libev will compile in support for the BSD style
		1824	<code>kqueue</code>(2) backend. Its actual availability will be detected at runtime,
		1825	otherwise another method will be used as fallback. This is the preferred
		1826	backend for BSD and BSD-like systems, although on most BSDs kqueue only
		1827	supports some types of fds correctly (the only platform we found that
		1828	supports ptys for example was NetBSD), so kqueue might be compiled in, but
		1829	not be used unless explicitly requested. The best way to use it is to find
		1830	out whether kqueue supports your type of fd properly and use an embedded
		1831	kqueue loop.</p>
		1832	</dd>
		1833	<dt>EV_USE_PORT</dt>
		1834	<dd>
		1835	<p>If defined to be <code>1</code>, libev will compile in support for the Solaris
		1836	10 port style backend. Its availability will be detected at runtime,
		1837	otherwise another method will be used as fallback. This is the preferred
		1838	backend for Solaris 10 systems.</p>
		1839	</dd>
		1840	<dt>EV_USE_DEVPOLL</dt>
		1841	<dd>
		1842	<p>reserved for future expansion, works like the USE symbols above.</p>
		1843	</dd>
		1844	<dt>EV_H</dt>
		1845	<dd>
		1846	<p>The name of the <cite>ev.h</cite> header file used to include it. The default if
		1847	undefined is <code><ev.h></code> in <cite>event.h</cite> and <code>"ev.h"</code> in <cite>ev.c</cite>. This
		1848	can be used to virtually rename the <cite>ev.h</cite> header file in case of conflicts.</p>
		1849	</dd>
		1850	<dt>EV_CONFIG_H</dt>
		1851	<dd>
		1852	<p>If <code>EV_STANDALONE</code> isn't <code>1</code>, this variable can be used to override
		1853	<cite>ev.c</cite>'s idea of where to find the <cite>config.h</cite> file, similarly to
		1854	<code>EV_H</code>, above.</p>
		1855	</dd>
		1856	<dt>EV_EVENT_H</dt>
		1857	<dd>
		1858	<p>Similarly to <code>EV_H</code>, this macro can be used to override <cite>event.c</cite>'s idea
		1859	of how the <cite>event.h</cite> header can be found.</p>
		1860	</dd>
		1861	<dt>EV_PROTOTYPES</dt>
		1862	<dd>
		1863	<p>If defined to be <code>0</code>, then <cite>ev.h</cite> will not define any function
		1864	prototypes, but still define all the structs and other symbols. This is
		1865	occasionally useful if you want to provide your own wrapper functions
		1866	around libev functions.</p>
		1867	</dd>
		1868	<dt>EV_MULTIPLICITY</dt>
		1869	<dd>
		1870	<p>If undefined or defined to <code>1</code>, then all event-loop-specific functions
		1871	will have the <code>struct ev_loop *</code> as first argument, and you can create
		1872	additional independent event loops. Otherwise there will be no support
		1873	for multiple event loops and there is no first event loop pointer
		1874	argument. Instead, all functions act on the single default loop.</p>
		1875	</dd>
		1876	<dt>EV_PERIODIC_ENABLE</dt>
		1877	<dd>
		1878	<p>If undefined or defined to be <code>1</code>, then periodic timers are supported. If
		1879	defined to be <code>0</code>, then they are not. Disabling them saves a few kB of
		1880	code.</p>
		1881	</dd>
		1882	<dt>EV_EMBED_ENABLE</dt>
		1883	<dd>
		1884	<p>If undefined or defined to be <code>1</code>, then embed watchers are supported. If
		1885	defined to be <code>0</code>, then they are not.</p>
		1886	</dd>
		1887	<dt>EV_STAT_ENABLE</dt>
		1888	<dd>
		1889	<p>If undefined or defined to be <code>1</code>, then stat watchers are supported. If
		1890	defined to be <code>0</code>, then they are not.</p>
		1891	</dd>
		1892	<dt>EV_MINIMAL</dt>
		1893	<dd>
		1894	<p>If you need to shave off some kilobytes of code at the expense of some
		1895	speed, define this symbol to <code>1</code>. Currently only used for gcc to override
		1896	some inlining decisions, saves roughly 30% codesize of amd64.</p>
		1897	</dd>
		1898	<dt>EV_COMMON</dt>
		1899	<dd>
		1900	<p>By default, all watchers have a <code>void *data</code> member. By redefining
		1901	this macro to a something else you can include more and other types of
		1902	members. You have to define it each time you include one of the files,
		1903	though, and it must be identical each time.</p>
		1904	<p>For example, the perl EV module uses something like this:</p>
		1905	<pre> #define EV_COMMON \
		1906	SV self; / contains this struct */ \
		1907	SV cb_sv, fh /* note no trailing ";" */
		1908
		1909	</pre>
		1910	</dd>
		1911	<dt>EV_CB_DECLARE (type)</dt>
		1912	<dt>EV_CB_INVOKE (watcher, revents)</dt>
		1913	<dt>ev_set_cb (ev, cb)</dt>
		1914	<dd>
		1915	<p>Can be used to change the callback member declaration in each watcher,
		1916	and the way callbacks are invoked and set. Must expand to a struct member
		1917	definition and a statement, respectively. See the <cite>ev.v</cite> header file for
		1918	their default definitions. One possible use for overriding these is to
		1919	avoid the <code>struct ev_loop *</code> as first argument in all cases, or to use
		1920	method calls instead of plain function calls in C++.</p>
		1921
		1922	</div>
		1923	<h2 id="EXAMPLES">EXAMPLES</h2>
		1924	<div id="EXAMPLES_CONTENT">
		1925	<p>For a real-world example of a program the includes libev
		1926	verbatim, you can have a look at the EV perl module
		1927	(<a href="http://software.schmorp.de/pkg/EV.html">http://software.schmorp.de/pkg/EV.html</a>). It has the libev files in
		1928	the <cite>libev/</cite> subdirectory and includes them in the <cite>EV/EVAPI.h</cite> (public
		1929	interface) and <cite>EV.xs</cite> (implementation) files. Only the <cite>EV.xs</cite> file
		1930	will be compiled. It is pretty complex because it provides its own header
		1931	file.</p>
		1932	<p>The usage in rxvt-unicode is simpler. It has a <cite>ev_cpp.h</cite> header file
		1933	that everybody includes and which overrides some autoconf choices:</p>
		1934	<pre> #define EV_USE_POLL 0
		1935	#define EV_MULTIPLICITY 0
		1936	#define EV_PERIODICS 0
		1937	#define EV_CONFIG_H <config.h>
		1938
		1939	#include "ev++.h"
		1940
		1941	</pre>
		1942	<p>And a <cite>ev_cpp.C</cite> implementation file that contains libev proper and is compiled:</p>
		1943	<pre> #include "ev_cpp.h"
		1944	#include "ev.c"
		1945
		1946
		1947
		1948
		1949	</pre>
		1950
		1951	</div>
		1952	<h1 id="COMPLEXITIES">COMPLEXITIES</h1><p><a href="#TOP" class="toplink">Top</a></p>
		1953	<div id="COMPLEXITIES_CONTENT">
		1954	<p>In this section the complexities of (many of) the algorithms used inside
		1955	libev will be explained. For complexity discussions about backends see the
		1956	documentation for <code>ev_default_init</code>.</p>
		1957	<p>
		1958	<dl>
		1959	<dt>Starting and stopping timer/periodic watchers: O(log skipped_other_timers)</dt>
		1960	<dt>Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)</dt>
		1961	<dt>Starting io/check/prepare/idle/signal/child watchers: O(1)</dt>
		1962	<dt>Stopping check/prepare/idle watchers: O(1)</dt>
		1963	<dt>Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % 16))</dt>
		1964	<dt>Finding the next timer per loop iteration: O(1)</dt>
		1965	<dt>Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)</dt>
		1966	<dt>Activating one watcher: O(1)</dt>
		1967	</dl>
		1968	</p>
		1969
		1970
		1971
		1972
1308		1973
1309	</div>	1974	</div>
1310	<h1 id="AUTHOR">AUTHOR</h1><p><a href="#TOP" class="toplink">Top</a></p>	1975	<h1 id="AUTHOR">AUTHOR</h1><p><a href="#TOP" class="toplink">Top</a></p>
1311	<div id="AUTHOR_CONTENT">	1976	<div id="AUTHOR_CONTENT">
1312	<p>Marc Lehmann <libev@schmorp.de>.</p>	1977	<p>Marc Lehmann <libev@schmorp.de>.</p>
1313		1978
1314	</div>	1979	</div>
1315	</div></body>	1980	</div></body>
1316	</html>	1981	</html>

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