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4	<head>	4	<head>
5	<title>libev</title>	5	<title>libev</title>
6	<meta name="description" content="Pod documentation for libev" />	6	<meta name="description" content="Pod documentation for libev" />
7	<meta name="inputfile" content="<standard input>" />	7	<meta name="inputfile" content="<standard input>" />
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9	<meta name="created" content="Sat Nov 24 05:58:35 2007" />	9	<meta name="created" content="Mon Nov 26 11:20:35 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="#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>
37	<li><a href="#code_ev_embed_code_when_one_backend_"><code>ev_embed</code> - when one backend isn't enough</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>
38	</ul>	39	</ul>
39	</li>	40	</li>
40	<li><a href="#OTHER_FUNCTIONS">OTHER FUNCTIONS</a></li>	41	<li><a href="#OTHER_FUNCTIONS">OTHER FUNCTIONS</a></li>
41	<li><a href="#LIBEVENT_EMULATION">LIBEVENT EMULATION</a></li>	42	<li><a href="#LIBEVENT_EMULATION">LIBEVENT EMULATION</a></li>
42	<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>
43	<li><a href="#AUTHOR">AUTHOR</a>	56	<li><a href="#AUTHOR">AUTHOR</a>
44	</li>	57	</li>
45	</ul><hr />	58	</ul><hr />
46	<!-- INDEX END -->	59	<!-- INDEX END -->
47		60
…		…
363	</pre>	376	</pre>
364	</dd>	377	</dd>
365	<dt>ev_default_destroy ()</dt>	378	<dt>ev_default_destroy ()</dt>
366	<dd>	379	<dd>
367	<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
368	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
369	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>
370	</dd>	387	</dd>
371	<dt>ev_loop_destroy (loop)</dt>	388	<dt>ev_loop_destroy (loop)</dt>
372	<dd>	389	<dd>
373	<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
374	earlier call to <code>ev_loop_new</code>.</p>	391	earlier call to <code>ev_loop_new</code>.</p>
…		…
497		514
498	</pre>	515	</pre>
499	</dd>	516	</dd>
500	</dl>	517	</dl>
501		518
		519
		520
		521
		522
502	</div>	523	</div>
503	<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>
504	<div id="ANATOMY_OF_A_WATCHER_CONTENT">	525	<div id="ANATOMY_OF_A_WATCHER_CONTENT">
505	<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
506	interest in some event. For instance, if you want to wait for STDIN to	527	interest in some event. For instance, if you want to wait for STDIN to
…		…
535	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
536	*)</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
537	corresponding stop function (<code>ev_<type>_stop (loop, watcher *)</code>.</p>	558	corresponding stop function (<code>ev_<type>_stop (loop, watcher *)</code>.</p>
538	<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
539	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
540	reinitialise it or call its set macro.</p>	561	reinitialise it or call its <code>set</code> macro.</p>
541	<p>You can check whether an event is active by calling the <code>ev_is_active
542	(watcher *)</code> macro. To see whether an event is outstanding (but the
543	callback for it has not been called yet) you can use the <code>ev_is_pending
544	(watcher *)</code> macro.</p>
545	<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
546	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
547	third argument.</p>	564	third argument.</p>
548	<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
549	(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
…		…
598	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
599	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
600	programs, though, so beware.</p>	617	programs, though, so beware.</p>
601	</dd>	618	</dd>
602	</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
603		698
604	</div>	699	</div>
605	<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>
606	<div id="ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH-2">	701	<div id="ASSOCIATING_CUSTOM_DATA_WITH_A_WATCH-2">
607	<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
…		…
644		739
645		740
646		741
647		742
648	</div>	743	</div>
649	<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>
650	<div id="code_ev_io_code_is_this_file_descrip-2">	745	<div id="code_ev_io_code_is_this_file_descrip-2">
651	<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
652	in each iteration of the event loop (This behaviour is called	747	in each iteration of the event loop, or, more precisely, when reading
653	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
654	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
655	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>
656	<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
657	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
658	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
659	required if you know what you are doing).</p>	756	required if you know what you are doing).</p>
660	<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
661	(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
662	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
663	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
664	the same underlying "file open").</p>	761	the same underlying "file open").</p>
665	<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
666	(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
667	<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>
668	<dl>	778	<dl>
669	<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>
670	<dt>ev_io_set (ev_io *, int fd, int events)</dt>	780	<dt>ev_io_set (ev_io *, int fd, int events)</dt>
671	<dd>	781	<dd>
672	<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
673	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
674	EV_WRITE</code> to receive the given events.</p>	784	<code>EV_READ \| EV_WRITE</code> to receive the given events.</p>
675	<p>Please note that most of the more scalable backend mechanisms (for example
676	epoll and solaris ports) can result in spurious readyness notifications
677	for file descriptors, so you practically need to use non-blocking I/O (and
678	treat callback invocation as hint only), or retest separately with a safe
679	interface before doing I/O (XLib can do this), or force the use of either
680	<code>EVBACKEND_SELECT</code> or <code>EVBACKEND_POLL</code>, which don't suffer from this
681	problem. Also note that it is quite easy to have your callback invoked
682	when the readyness condition is no longer valid even when employing
683	typical ways of handling events, so its a good idea to use non-blocking
684	I/O unconditionally.</p>
685	</dd>	785	</dd>
686	</dl>	786	</dl>
687	<p>Example: call <code>stdin_readable_cb</code> when STDIN_FILENO has become, well	787	<p>Example: call <code>stdin_readable_cb</code> when STDIN_FILENO has become, well
688	readable, but only once. Since it is likely line-buffered, you could	788	readable, but only once. Since it is likely line-buffered, you could
689	attempt to read a whole line in the callback:</p>	789	attempt to read a whole line in the callback:</p>
…		…
705		805
706		806
707	</pre>	807	</pre>
708		808
709	</div>	809	</div>
710	<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>
711	<div id="code_ev_timer_code_relative_and_opti-2">	811	<div id="code_ev_timer_code_relative_and_opti-2">
712	<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
713	given time, and optionally repeating in regular intervals after that.</p>	813	given time, and optionally repeating in regular intervals after that.</p>
714	<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
715	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
…		…
791		891
792		892
793	</pre>	893	</pre>
794		894
795	</div>	895	</div>
796	<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>
797	<div id="code_ev_periodic_code_to_cron_or_not-2">	897	<div id="code_ev_periodic_code_to_cron_or_not-2">
798	<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
799	(and unfortunately a bit complex).</p>	899	(and unfortunately a bit complex).</p>
800	<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)
801	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
802	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
803	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 ()
804	+ 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
805	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
806	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
807	again).</p>	907	again).</p>
808	<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
809	triggering an event on eahc midnight, local time.</p>	909	triggering an event on eahc midnight, local time.</p>
…		…
920		1020
921		1021
922	</pre>	1022	</pre>
923		1023
924	</div>	1024	</div>
925	<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>
926	<div id="code_ev_signal_code_signal_me_when_a-2">	1026	<div id="code_ev_signal_code_signal_me_when_a-2">
927	<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
928	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
929	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
930	normal event processing, like any other event.</p>	1030	normal event processing, like any other event.</p>
…		…
946		1046
947		1047
948		1048
949		1049
950	</div>	1050	</div>
951	<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>
952	<div id="code_ev_child_code_wait_for_pid_stat-2">	1052	<div id="code_ev_child_code_watch_out_for_pro-2">
953	<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
954	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>
955	<dl>	1055	<dl>
956	<dt>ev_child_init (ev_child *, callback, int pid)</dt>	1056	<dt>ev_child_init (ev_child *, callback, int pid)</dt>
957	<dt>ev_child_set (ev_child *, int pid)</dt>	1057	<dt>ev_child_set (ev_child *, int pid)</dt>
…		…
979		1079
980		1080
981	</pre>	1081	</pre>
982		1082
983	</div>	1083	</div>
984	<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>
985	<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">
986	<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
987	(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
988	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,
989	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
…		…
1022		1122
1023		1123
1024	</pre>	1124	</pre>
1025		1125
1026	</div>	1126	</div>
1027	<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>
1028	<div id="code_ev_prepare_code_and_code_ev_che-2">	1128	<div id="code_ev_prepare_code_and_code_ev_che-2">
1029	<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:
1030	prepare watchers get invoked before the process blocks and check watchers	1130	prepare watchers get invoked before the process blocks and check watchers
1031	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>
1032	<p>Their main purpose is to integrate other event mechanisms into libev and	1139	<p>Their main purpose is to integrate other event mechanisms into libev and
1033	their use is somewhat advanced. This could be used, for example, to track	1140	their use is somewhat advanced. This could be used, for example, to track
1034	variable changes, implement your own watchers, integrate net-snmp or a	1141	variable changes, implement your own watchers, integrate net-snmp or a
1035	coroutine library and lots more.</p>	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>
1036	<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
1037	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
1038	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
1039	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
1040	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
…		…
1056	<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
1057	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>
1058	macros, but using them is utterly, utterly and completely pointless.</p>	1168	macros, but using them is utterly, utterly and completely pointless.</p>
1059	</dd>	1169	</dd>
1060	</dl>	1170	</dl>
1061	<p>Example: TODO.</p>	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;
1062		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	}
1063		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 ()));
1064		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);
1065		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)));
1066		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
1067	</div>	1230	</div>
1068	<h2 id="code_ev_embed_code_when_one_backend_"><code>ev_embed</code> - when one backend isn't enough</h2>	1231	<h2 id="code_ev_embed_code_when_one_backend_"><code>ev_embed</code> - when one backend isn't enough...</h2>
1069	<div id="code_ev_embed_code_when_one_backend_-2">	1232	<div id="code_ev_embed_code_when_one_backend_-2">
1070	<p>This is a rather advanced watcher type that lets you embed one event loop	1233	<p>This is a rather advanced watcher type that lets you embed one event loop
1071	into another.</p>	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>
1072	<p>There are primarily two reasons you would want that: work around bugs and	1237	<p>There are primarily two reasons you would want that: work around bugs and
1073	prioritise I/O.</p>	1238	prioritise I/O.</p>
1074	<p>As an example for a bug workaround, the kqueue backend might only support	1239	<p>As an example for a bug workaround, the kqueue backend might only support
1075	sockets on some platform, so it is unusable as generic backend, but you	1240	sockets on some platform, so it is unusable as generic backend, but you
1076	still want to make use of it because you have many sockets and it scales	1241	still want to make use of it because you have many sockets and it scales
…		…
1081	<p>As for prioritising I/O: rarely you have the case where some fds have	1246	<p>As for prioritising I/O: rarely you have the case where some fds have
1082	to be watched and handled very quickly (with low latency), and even	1247	to be watched and handled very quickly (with low latency), and even
1083	priorities and idle watchers might have too much overhead. In this case	1248	priorities and idle watchers might have too much overhead. In this case
1084	you would put all the high priority stuff in one loop and all the rest in	1249	you would put all the high priority stuff in one loop and all the rest in
1085	a second one, and embed the second one in the first.</p>	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>
1086	<p>As long as the watcher is started it will automatically handle events. The	1258	<p>As long as the watcher is started it will automatically handle events. The
1087	callback will be invoked whenever some events have been handled. You can	1259	callback will be invoked whenever some events have been handled. You can
1088	set the callback to <code>0</code> to avoid having to specify one if you are not	1260	set the callback to <code>0</code> to avoid having to specify one if you are not
1089	interested in that.</p>	1261	interested in that.</p>
1090	<p>Also, there have not currently been made special provisions for forking:	1262	<p>Also, there have not currently been made special provisions for forking:
…		…
1117	else	1289	else
1118	loop_lo = loop_hi;	1290	loop_lo = loop_hi;
1119		1291
1120	</pre>	1292	</pre>
1121	<dl>	1293	<dl>
1122	<dt>ev_embed_init (ev_embed , callback, struct ev_loop loop)</dt>	1294	<dt>ev_embed_init (ev_embed , callback, struct ev_loop embedded_loop)</dt>
1123	<dt>ev_embed_set (ev_embed , callback, struct ev_loop 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>
1124	<dd>	1302	</dd>
1125	<p>Configures the watcher to embed the given loop, which must be embeddable.</p>	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>
1126	</dd>	1308	</dd>
1127	</dl>	1309	</dl>
1128		1310
1129		1311
1130		1312
…		…
1163		1345
1164	ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);	1346	ev_once (STDIN_FILENO, EV_READ, 10., stdin_ready, 0);
1165		1347
1166	</pre>	1348	</pre>
1167	</dd>	1349	</dd>
1168	<dt>ev_feed_event (loop, watcher, int events)</dt>	1350	<dt>ev_feed_event (ev_loop , watcher , int revents)</dt>
1169	<dd>	1351	<dd>
1170	<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
1171	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
1172	initialised but not necessarily started event watcher).</p>	1354	initialised but not necessarily started event watcher).</p>
1173	</dd>	1355	</dd>
1174	<dt>ev_feed_fd_event (loop, int fd, int revents)</dt>	1356	<dt>ev_feed_fd_event (ev_loop *, int fd, int revents)</dt>
1175	<dd>	1357	<dd>
1176	<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
1177	the given events it.</p>	1359	the given events it.</p>
1178	</dd>	1360	</dd>
1179	<dt>ev_feed_signal_event (loop, int signum)</dt>	1361	<dt>ev_feed_signal_event (ev_loop *loop, int signum)</dt>
1180	<dd>	1362	<dd>
1181	<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>
1182	</dd>	1365	</dd>
1183	</dl>	1366	</dl>
1184		1367
1185		1368
1186		1369
…		…
1207	</dl>	1390	</dl>
1208		1391
1209	</div>	1392	</div>
1210	<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>
1211	<div id="C_SUPPORT_CONTENT">	1394	<div id="C_SUPPORT_CONTENT">
1212	<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
1213		1787
1214	</div>	1788	</div>
1215	<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>
1216	<div id="AUTHOR_CONTENT">	1790	<div id="AUTHOR_CONTENT">
1217	<p>Marc Lehmann <libev@schmorp.de>.</p>	1791	<p>Marc Lehmann <libev@schmorp.de>.</p>
1218		1792
1219	</div>	1793	</div>
1220	</div></body>	1794	</div></body>
1221	</html>	1795	</html>

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