[ViewVC] Diff of: cvs/libev/ev.pod

Comparing libev/ev.pod (file contents):
Revision 1.203 by root, Sun Oct 26 00:52:51 2008 UTC vs.
Revision 1.231 by root, Wed Apr 15 19:35:53 2009 UTC

…		…
8		8
9	=head2 EXAMPLE PROGRAM	9	=head2 EXAMPLE PROGRAM
10		10
11	// a single header file is required	11	// a single header file is required
12	#include <ev.h>	12	#include <ev.h>
		13
		14	#include <stdio.h> // for puts
13		15
14	// every watcher type has its own typedef'd struct	16	// every watcher type has its own typedef'd struct
15	// with the name ev_TYPE	17	// with the name ev_TYPE
16	ev_io stdin_watcher;	18	ev_io stdin_watcher;
17	ev_timer timeout_watcher;	19	ev_timer timeout_watcher;
…		…
41		43
42	int	44	int
43	main (void)	45	main (void)
44	{	46	{
45	// use the default event loop unless you have special needs	47	// use the default event loop unless you have special needs
46	ev_loop *loop = ev_default_loop (0);	48	struct ev_loop *loop = ev_default_loop (0);
47		49
48	// initialise an io watcher, then start it	50	// initialise an io watcher, then start it
49	// this one will watch for stdin to become readable	51	// this one will watch for stdin to become readable
50	ev_io_init (&stdin_watcher, stdin_cb, /STDIN_FILENO/ 0, EV_READ);	52	ev_io_init (&stdin_watcher, stdin_cb, /STDIN_FILENO/ 0, EV_READ);
51	ev_io_start (loop, &stdin_watcher);	53	ev_io_start (loop, &stdin_watcher);
…		…
298	If you don't know what event loop to use, use the one returned from this	300	If you don't know what event loop to use, use the one returned from this
299	function.	301	function.
300		302
301	Note that this function is I<not> thread-safe, so if you want to use it	303	Note that this function is I<not> thread-safe, so if you want to use it
302	from multiple threads, you have to lock (note also that this is unlikely,	304	from multiple threads, you have to lock (note also that this is unlikely,
303	as loops cannot bes hared easily between threads anyway).	305	as loops cannot be shared easily between threads anyway).
304		306
305	The default loop is the only loop that can handle C<ev_signal> and	307	The default loop is the only loop that can handle C<ev_signal> and
306	C<ev_child> watchers, and to do this, it always registers a handler	308	C<ev_child> watchers, and to do this, it always registers a handler
307	for C<SIGCHLD>. If this is a problem for your application you can either	309	for C<SIGCHLD>. If this is a problem for your application you can either
308	create a dynamic loop with C<ev_loop_new> that doesn't do that, or you	310	create a dynamic loop with C<ev_loop_new> that doesn't do that, or you
…		…
384	=item C<EVBACKEND_EPOLL> (value 4, Linux)	386	=item C<EVBACKEND_EPOLL> (value 4, Linux)
385		387
386	For few fds, this backend is a bit little slower than poll and select,	388	For few fds, this backend is a bit little slower than poll and select,
387	but it scales phenomenally better. While poll and select usually scale	389	but it scales phenomenally better. While poll and select usually scale
388	like O(total_fds) where n is the total number of fds (or the highest fd),	390	like O(total_fds) where n is the total number of fds (or the highest fd),
389	epoll scales either O(1) or O(active_fds). The epoll design has a number	391	epoll scales either O(1) or O(active_fds).
390	of shortcomings, such as silently dropping events in some hard-to-detect	392
391	cases and requiring a system call per fd change, no fork support and bad	393	The epoll mechanism deserves honorable mention as the most misdesigned
392	support for dup.	394	of the more advanced event mechanisms: mere annoyances include silently
		395	dropping file descriptors, requiring a system call per change per file
		396	descriptor (and unnecessary guessing of parameters), problems with dup and
		397	so on. The biggest issue is fork races, however - if a program forks then
		398	I<both> parent and child process have to recreate the epoll set, which can
		399	take considerable time (one syscall per file descriptor) and is of course
		400	hard to detect.
		401
		402	Epoll is also notoriously buggy - embedding epoll fds I<should> work, but
		403	of course I<doesn't>, and epoll just loves to report events for totally
		404	I<different> file descriptors (even already closed ones, so one cannot
		405	even remove them from the set) than registered in the set (especially
		406	on SMP systems). Libev tries to counter these spurious notifications by
		407	employing an additional generation counter and comparing that against the
		408	events to filter out spurious ones, recreating the set when required.
393		409
394	While stopping, setting and starting an I/O watcher in the same iteration	410	While stopping, setting and starting an I/O watcher in the same iteration
395	will result in some caching, there is still a system call per such incident	411	will result in some caching, there is still a system call per such
396	(because the fd could point to a different file description now), so its	412	incident (because the same I<file descriptor> could point to a different
397	best to avoid that. Also, C<dup ()>'ed file descriptors might not work	413	I<file description> now), so its best to avoid that. Also, C<dup ()>'ed
398	very well if you register events for both fds.	414	file descriptors might not work very well if you register events for both
399		415	file descriptors.
400	Please note that epoll sometimes generates spurious notifications, so you
401	need to use non-blocking I/O or other means to avoid blocking when no data
402	(or space) is available.
403		416
404	Best performance from this backend is achieved by not unregistering all	417	Best performance from this backend is achieved by not unregistering all
405	watchers for a file descriptor until it has been closed, if possible,	418	watchers for a file descriptor until it has been closed, if possible,
406	i.e. keep at least one watcher active per fd at all times. Stopping and	419	i.e. keep at least one watcher active per fd at all times. Stopping and
407	starting a watcher (without re-setting it) also usually doesn't cause	420	starting a watcher (without re-setting it) also usually doesn't cause
408	extra overhead.	421	extra overhead. A fork can both result in spurious notifications as well
		422	as in libev having to destroy and recreate the epoll object, which can
		423	take considerable time and thus should be avoided.
		424
		425	All this means that, in practice, C<EVBACKEND_SELECT> can be as fast or
		426	faster than epoll for maybe up to a hundred file descriptors, depending on
		427	the usage. So sad.
409		428
410	While nominally embeddable in other event loops, this feature is broken in	429	While nominally embeddable in other event loops, this feature is broken in
411	all kernel versions tested so far.	430	all kernel versions tested so far.
412		431
413	This backend maps C<EV_READ> and C<EV_WRITE> in the same way as	432	This backend maps C<EV_READ> and C<EV_WRITE> in the same way as
414	C<EVBACKEND_POLL>.	433	C<EVBACKEND_POLL>.
415		434
416	=item C<EVBACKEND_KQUEUE> (value 8, most BSD clones)	435	=item C<EVBACKEND_KQUEUE> (value 8, most BSD clones)
417		436
418	Kqueue deserves special mention, as at the time of this writing, it was	437	Kqueue deserves special mention, as at the time of this writing, it
419	broken on all BSDs except NetBSD (usually it doesn't work reliably with	438	was broken on all BSDs except NetBSD (usually it doesn't work reliably
420	anything but sockets and pipes, except on Darwin, where of course it's	439	with anything but sockets and pipes, except on Darwin, where of course
421	completely useless). For this reason it's not being "auto-detected" unless	440	it's completely useless). Unlike epoll, however, whose brokenness
422	you explicitly specify it in the flags (i.e. using C<EVBACKEND_KQUEUE>) or	441	is by design, these kqueue bugs can (and eventually will) be fixed
423	libev was compiled on a known-to-be-good (-enough) system like NetBSD.	442	without API changes to existing programs. For this reason it's not being
		443	"auto-detected" unless you explicitly specify it in the flags (i.e. using
		444	C<EVBACKEND_KQUEUE>) or libev was compiled on a known-to-be-good (-enough)
		445	system like NetBSD.
424		446
425	You still can embed kqueue into a normal poll or select backend and use it	447	You still can embed kqueue into a normal poll or select backend and use it
426	only for sockets (after having made sure that sockets work with kqueue on	448	only for sockets (after having made sure that sockets work with kqueue on
427	the target platform). See C<ev_embed> watchers for more info.	449	the target platform). See C<ev_embed> watchers for more info.
428		450
429	It scales in the same way as the epoll backend, but the interface to the	451	It scales in the same way as the epoll backend, but the interface to the
430	kernel is more efficient (which says nothing about its actual speed, of	452	kernel is more efficient (which says nothing about its actual speed, of
431	course). While stopping, setting and starting an I/O watcher does never	453	course). While stopping, setting and starting an I/O watcher does never
432	cause an extra system call as with C<EVBACKEND_EPOLL>, it still adds up to	454	cause an extra system call as with C<EVBACKEND_EPOLL>, it still adds up to
433	two event changes per incident. Support for C<fork ()> is very bad and it	455	two event changes per incident. Support for C<fork ()> is very bad (but
434	drops fds silently in similarly hard-to-detect cases.	456	sane, unlike epoll) and it drops fds silently in similarly hard-to-detect
		457	cases
435		458
436	This backend usually performs well under most conditions.	459	This backend usually performs well under most conditions.
437		460
438	While nominally embeddable in other event loops, this doesn't work	461	While nominally embeddable in other event loops, this doesn't work
439	everywhere, so you might need to test for this. And since it is broken	462	everywhere, so you might need to test for this. And since it is broken
440	almost everywhere, you should only use it when you have a lot of sockets	463	almost everywhere, you should only use it when you have a lot of sockets
441	(for which it usually works), by embedding it into another event loop	464	(for which it usually works), by embedding it into another event loop
442	(e.g. C<EVBACKEND_SELECT> or C<EVBACKEND_POLL>) and, did I mention it,	465	(e.g. C<EVBACKEND_SELECT> or C<EVBACKEND_POLL> (but C<poll> is of course
443	using it only for sockets.	466	also broken on OS X)) and, did I mention it, using it only for sockets.
444		467
445	This backend maps C<EV_READ> into an C<EVFILT_READ> kevent with	468	This backend maps C<EV_READ> into an C<EVFILT_READ> kevent with
446	C<NOTE_EOF>, and C<EV_WRITE> into an C<EVFILT_WRITE> kevent with	469	C<NOTE_EOF>, and C<EV_WRITE> into an C<EVFILT_WRITE> kevent with
447	C<NOTE_EOF>.	470	C<NOTE_EOF>.
448		471
…		…
468	might perform better.	491	might perform better.
469		492
470	On the positive side, with the exception of the spurious readiness	493	On the positive side, with the exception of the spurious readiness
471	notifications, this backend actually performed fully to specification	494	notifications, this backend actually performed fully to specification
472	in all tests and is fully embeddable, which is a rare feat among the	495	in all tests and is fully embeddable, which is a rare feat among the
473	OS-specific backends.	496	OS-specific backends (I vastly prefer correctness over speed hacks).
474		497
475	This backend maps C<EV_READ> and C<EV_WRITE> in the same way as	498	This backend maps C<EV_READ> and C<EV_WRITE> in the same way as
476	C<EVBACKEND_POLL>.	499	C<EVBACKEND_POLL>.
477		500
478	=item C<EVBACKEND_ALL>	501	=item C<EVBACKEND_ALL>
…		…
611	very long time without entering the event loop, updating libev's idea of	634	very long time without entering the event loop, updating libev's idea of
612	the current time is a good idea.	635	the current time is a good idea.
613		636
614	See also "The special problem of time updates" in the C<ev_timer> section.	637	See also "The special problem of time updates" in the C<ev_timer> section.
615		638
		639	=item ev_suspend (loop)
		640
		641	=item ev_resume (loop)
		642
		643	These two functions suspend and resume a loop, for use when the loop is
		644	not used for a while and timeouts should not be processed.
		645
		646	A typical use case would be an interactive program such as a game: When
		647	the user presses C<^Z> to suspend the game and resumes it an hour later it
		648	would be best to handle timeouts as if no time had actually passed while
		649	the program was suspended. This can be achieved by calling C<ev_suspend>
		650	in your C<SIGTSTP> handler, sending yourself a C<SIGSTOP> and calling
		651	C<ev_resume> directly afterwards to resume timer processing.
		652
		653	Effectively, all C<ev_timer> watchers will be delayed by the time spend
		654	between C<ev_suspend> and C<ev_resume>, and all C<ev_periodic> watchers
		655	will be rescheduled (that is, they will lose any events that would have
		656	occured while suspended).
		657
		658	After calling C<ev_suspend> you B<must not> call I<any> function on the
		659	given loop other than C<ev_resume>, and you B<must not> call C<ev_resume>
		660	without a previous call to C<ev_suspend>.
		661
		662	Calling C<ev_suspend>/C<ev_resume> has the side effect of updating the
		663	event loop time (see C<ev_now_update>).
		664
616	=item ev_loop (loop, int flags)	665	=item ev_loop (loop, int flags)
617		666
618	Finally, this is it, the event handler. This function usually is called	667	Finally, this is it, the event handler. This function usually is called
619	after you initialised all your watchers and you want to start handling	668	after you initialised all your watchers and you want to start handling
620	events.	669	events.
…		…
635	the loop.	684	the loop.
636		685
637	A flags value of C<EVLOOP_ONESHOT> will look for new events (waiting if	686	A flags value of C<EVLOOP_ONESHOT> will look for new events (waiting if
638	necessary) and will handle those and any already outstanding ones. It	687	necessary) and will handle those and any already outstanding ones. It
639	will block your process until at least one new event arrives (which could	688	will block your process until at least one new event arrives (which could
640	be an event internal to libev itself, so there is no guarentee that a	689	be an event internal to libev itself, so there is no guarantee that a
641	user-registered callback will be called), and will return after one	690	user-registered callback will be called), and will return after one
642	iteration of the loop.	691	iteration of the loop.
643		692
644	This is useful if you are waiting for some external event in conjunction	693	This is useful if you are waiting for some external event in conjunction
645	with something not expressible using other libev watchers (i.e. "roll your	694	with something not expressible using other libev watchers (i.e. "roll your
…		…
703		752
704	If you have a watcher you never unregister that should not keep C<ev_loop>	753	If you have a watcher you never unregister that should not keep C<ev_loop>
705	from returning, call ev_unref() after starting, and ev_ref() before	754	from returning, call ev_unref() after starting, and ev_ref() before
706	stopping it.	755	stopping it.
707		756
708	As an example, libev itself uses this for its internal signal pipe: It is	757	As an example, libev itself uses this for its internal signal pipe: It
709	not visible to the libev user and should not keep C<ev_loop> from exiting	758	is not visible to the libev user and should not keep C<ev_loop> from
710	if no event watchers registered by it are active. It is also an excellent	759	exiting if no event watchers registered by it are active. It is also an
711	way to do this for generic recurring timers or from within third-party	760	excellent way to do this for generic recurring timers or from within
712	libraries. Just remember to I<unref after start> and I<ref before stop>	761	third-party libraries. Just remember to I<unref after start> and I<ref
713	(but only if the watcher wasn't active before, or was active before,	762	before stop> (but only if the watcher wasn't active before, or was active
714	respectively).	763	before, respectively. Note also that libev might stop watchers itself
		764	(e.g. non-repeating timers) in which case you have to C<ev_ref>
		765	in the callback).
715		766
716	Example: Create a signal watcher, but keep it from keeping C<ev_loop>	767	Example: Create a signal watcher, but keep it from keeping C<ev_loop>
717	running when nothing else is active.	768	running when nothing else is active.
718		769
719	ev_signal exitsig;	770	ev_signal exitsig;
…		…
902	C<ev_fork>).	953	C<ev_fork>).
903		954
904	=item C<EV_ASYNC>	955	=item C<EV_ASYNC>
905		956
906	The given async watcher has been asynchronously notified (see C<ev_async>).	957	The given async watcher has been asynchronously notified (see C<ev_async>).
		958
		959	=item C<EV_CUSTOM>
		960
		961	Not ever sent (or otherwise used) by libev itself, but can be freely used
		962	by libev users to signal watchers (e.g. via C<ev_feed_event>).
907		963
908	=item C<EV_ERROR>	964	=item C<EV_ERROR>
909		965
910	An unspecified error has occurred, the watcher has been stopped. This might	966	An unspecified error has occurred, the watcher has been stopped. This might
911	happen because the watcher could not be properly started because libev	967	happen because the watcher could not be properly started because libev
…		…
1294	year, it will still time out after (roughly) one hour. "Roughly" because	1350	year, it will still time out after (roughly) one hour. "Roughly" because
1295	detecting time jumps is hard, and some inaccuracies are unavoidable (the	1351	detecting time jumps is hard, and some inaccuracies are unavoidable (the
1296	monotonic clock option helps a lot here).	1352	monotonic clock option helps a lot here).
1297		1353
1298	The callback is guaranteed to be invoked only I<after> its timeout has	1354	The callback is guaranteed to be invoked only I<after> its timeout has
1299	passed, but if multiple timers become ready during the same loop iteration	1355	passed. If multiple timers become ready during the same loop iteration
1300	then order of execution is undefined.	1356	then the ones with earlier time-out values are invoked before ones with
		1357	later time-out values (but this is no longer true when a callback calls
		1358	C<ev_loop> recursively).
1301		1359
1302	=head3 Be smart about timeouts	1360	=head3 Be smart about timeouts
1303		1361
1304	Many real-world problems involve some kind of timeout, usually for error	1362	Many real-world problems involve some kind of timeout, usually for error
1305	recovery. A typical example is an HTTP request - if the other side hangs,	1363	recovery. A typical example is an HTTP request - if the other side hangs,
…		…
1398	else	1456	else
1399	{	1457	{
1400	// callback was invoked, but there was some activity, re-arm	1458	// callback was invoked, but there was some activity, re-arm
1401	// the watcher to fire in last_activity + 60, which is	1459	// the watcher to fire in last_activity + 60, which is
1402	// guaranteed to be in the future, so "again" is positive:	1460	// guaranteed to be in the future, so "again" is positive:
1403	w->again = timeout - now;	1461	w->repeat = timeout - now;
1404	ev_timer_again (EV_A_ w);	1462	ev_timer_again (EV_A_ w);
1405	}	1463	}
1406	}	1464	}
1407		1465
1408	To summarise the callback: first calculate the real timeout (defined	1466	To summarise the callback: first calculate the real timeout (defined
…		…
1573	=head2 C<ev_periodic> - to cron or not to cron?	1631	=head2 C<ev_periodic> - to cron or not to cron?
1574		1632
1575	Periodic watchers are also timers of a kind, but they are very versatile	1633	Periodic watchers are also timers of a kind, but they are very versatile
1576	(and unfortunately a bit complex).	1634	(and unfortunately a bit complex).
1577		1635
1578	Unlike C<ev_timer>'s, they are not based on real time (or relative time)	1636	Unlike C<ev_timer>, periodic watchers are not based on real time (or
1579	but on wall clock time (absolute time). You can tell a periodic watcher	1637	relative time, the physical time that passes) but on wall clock time
1580	to trigger after some specific point in time. For example, if you tell a	1638	(absolute time, the thing you can read on your calender or clock). The
1581	periodic watcher to trigger in 10 seconds (by specifying e.g. C<ev_now ()	1639	difference is that wall clock time can run faster or slower than real
1582	+ 10.>, that is, an absolute time not a delay) and then reset your system	1640	time, and time jumps are not uncommon (e.g. when you adjust your
1583	clock to January of the previous year, then it will take more than year	1641	wrist-watch).
1584	to trigger the event (unlike an C<ev_timer>, which would still trigger
1585	roughly 10 seconds later as it uses a relative timeout).
1586		1642
		1643	You can tell a periodic watcher to trigger after some specific point
		1644	in time: for example, if you tell a periodic watcher to trigger "in 10
		1645	seconds" (by specifying e.g. C<ev_now () + 10.>, that is, an absolute time
		1646	not a delay) and then reset your system clock to January of the previous
		1647	year, then it will take a year or more to trigger the event (unlike an
		1648	C<ev_timer>, which would still trigger roughly 10 seconds after starting
		1649	it, as it uses a relative timeout).
		1650
1587	C<ev_periodic>s can also be used to implement vastly more complex timers,	1651	C<ev_periodic> watchers can also be used to implement vastly more complex
1588	such as triggering an event on each "midnight, local time", or other	1652	timers, such as triggering an event on each "midnight, local time", or
1589	complicated rules.	1653	other complicated rules. This cannot be done with C<ev_timer> watchers, as
		1654	those cannot react to time jumps.
1590		1655
1591	As with timers, the callback is guaranteed to be invoked only when the	1656	As with timers, the callback is guaranteed to be invoked only when the
1592	time (C<at>) has passed, but if multiple periodic timers become ready	1657	point in time where it is supposed to trigger has passed. If multiple
1593	during the same loop iteration, then order of execution is undefined.	1658	timers become ready during the same loop iteration then the ones with
		1659	earlier time-out values are invoked before ones with later time-out values
		1660	(but this is no longer true when a callback calls C<ev_loop> recursively).
1594		1661
1595	=head3 Watcher-Specific Functions and Data Members	1662	=head3 Watcher-Specific Functions and Data Members
1596		1663
1597	=over 4	1664	=over 4
1598		1665
1599	=item ev_periodic_init (ev_periodic *, callback, ev_tstamp at, ev_tstamp interval, reschedule_cb)	1666	=item ev_periodic_init (ev_periodic *, callback, ev_tstamp offset, ev_tstamp interval, reschedule_cb)
1600		1667
1601	=item ev_periodic_set (ev_periodic *, ev_tstamp after, ev_tstamp repeat, reschedule_cb)	1668	=item ev_periodic_set (ev_periodic *, ev_tstamp offset, ev_tstamp interval, reschedule_cb)
1602		1669
1603	Lots of arguments, lets sort it out... There are basically three modes of	1670	Lots of arguments, let's sort it out... There are basically three modes of
1604	operation, and we will explain them from simplest to most complex:	1671	operation, and we will explain them from simplest to most complex:
1605		1672
1606	=over 4	1673	=over 4
1607		1674
1608	=item * absolute timer (at = time, interval = reschedule_cb = 0)	1675	=item * absolute timer (offset = absolute time, interval = 0, reschedule_cb = 0)
1609		1676
1610	In this configuration the watcher triggers an event after the wall clock	1677	In this configuration the watcher triggers an event after the wall clock
1611	time C<at> has passed. It will not repeat and will not adjust when a time	1678	time C<offset> has passed. It will not repeat and will not adjust when a
1612	jump occurs, that is, if it is to be run at January 1st 2011 then it will	1679	time jump occurs, that is, if it is to be run at January 1st 2011 then it
1613	only run when the system clock reaches or surpasses this time.	1680	will be stopped and invoked when the system clock reaches or surpasses
		1681	this point in time.
1614		1682
1615	=item * repeating interval timer (at = offset, interval > 0, reschedule_cb = 0)	1683	=item * repeating interval timer (offset = offset within interval, interval > 0, reschedule_cb = 0)
1616		1684
1617	In this mode the watcher will always be scheduled to time out at the next	1685	In this mode the watcher will always be scheduled to time out at the next
1618	C<at + N * interval> time (for some integer N, which can also be negative)	1686	C<offset + N * interval> time (for some integer N, which can also be
1619	and then repeat, regardless of any time jumps.	1687	negative) and then repeat, regardless of any time jumps. The C<offset>
		1688	argument is merely an offset into the C<interval> periods.
1620		1689
1621	This can be used to create timers that do not drift with respect to the	1690	This can be used to create timers that do not drift with respect to the
1622	system clock, for example, here is a C<ev_periodic> that triggers each	1691	system clock, for example, here is an C<ev_periodic> that triggers each
1623	hour, on the hour:	1692	hour, on the hour (with respect to UTC):
1624		1693
1625	ev_periodic_set (&periodic, 0., 3600., 0);	1694	ev_periodic_set (&periodic, 0., 3600., 0);
1626		1695
1627	This doesn't mean there will always be 3600 seconds in between triggers,	1696	This doesn't mean there will always be 3600 seconds in between triggers,
1628	but only that the callback will be called when the system time shows a	1697	but only that the callback will be called when the system time shows a
1629	full hour (UTC), or more correctly, when the system time is evenly divisible	1698	full hour (UTC), or more correctly, when the system time is evenly divisible
1630	by 3600.	1699	by 3600.
1631		1700
1632	Another way to think about it (for the mathematically inclined) is that	1701	Another way to think about it (for the mathematically inclined) is that
1633	C<ev_periodic> will try to run the callback in this mode at the next possible	1702	C<ev_periodic> will try to run the callback in this mode at the next possible
1634	time where C<time = at (mod interval)>, regardless of any time jumps.	1703	time where C<time = offset (mod interval)>, regardless of any time jumps.
1635		1704
1636	For numerical stability it is preferable that the C<at> value is near	1705	For numerical stability it is preferable that the C<offset> value is near
1637	C<ev_now ()> (the current time), but there is no range requirement for	1706	C<ev_now ()> (the current time), but there is no range requirement for
1638	this value, and in fact is often specified as zero.	1707	this value, and in fact is often specified as zero.
1639		1708
1640	Note also that there is an upper limit to how often a timer can fire (CPU	1709	Note also that there is an upper limit to how often a timer can fire (CPU
1641	speed for example), so if C<interval> is very small then timing stability	1710	speed for example), so if C<interval> is very small then timing stability
1642	will of course deteriorate. Libev itself tries to be exact to be about one	1711	will of course deteriorate. Libev itself tries to be exact to be about one
1643	millisecond (if the OS supports it and the machine is fast enough).	1712	millisecond (if the OS supports it and the machine is fast enough).
1644		1713
1645	=item * manual reschedule mode (at and interval ignored, reschedule_cb = callback)	1714	=item * manual reschedule mode (offset ignored, interval ignored, reschedule_cb = callback)
1646		1715
1647	In this mode the values for C<interval> and C<at> are both being	1716	In this mode the values for C<interval> and C<offset> are both being
1648	ignored. Instead, each time the periodic watcher gets scheduled, the	1717	ignored. Instead, each time the periodic watcher gets scheduled, the
1649	reschedule callback will be called with the watcher as first, and the	1718	reschedule callback will be called with the watcher as first, and the
1650	current time as second argument.	1719	current time as second argument.
1651		1720
1652	NOTE: I<This callback MUST NOT stop or destroy any periodic watcher,	1721	NOTE: I<This callback MUST NOT stop or destroy any periodic watcher, ever,
1653	ever, or make ANY event loop modifications whatsoever>.	1722	or make ANY other event loop modifications whatsoever, unless explicitly
		1723	allowed by documentation here>.
1654		1724
1655	If you need to stop it, return C<now + 1e30> (or so, fudge fudge) and stop	1725	If you need to stop it, return C<now + 1e30> (or so, fudge fudge) and stop
1656	it afterwards (e.g. by starting an C<ev_prepare> watcher, which is the	1726	it afterwards (e.g. by starting an C<ev_prepare> watcher, which is the
1657	only event loop modification you are allowed to do).	1727	only event loop modification you are allowed to do).
1658		1728
…		…
1688	a different time than the last time it was called (e.g. in a crond like	1758	a different time than the last time it was called (e.g. in a crond like
1689	program when the crontabs have changed).	1759	program when the crontabs have changed).
1690		1760
1691	=item ev_tstamp ev_periodic_at (ev_periodic *)	1761	=item ev_tstamp ev_periodic_at (ev_periodic *)
1692		1762
1693	When active, returns the absolute time that the watcher is supposed to	1763	When active, returns the absolute time that the watcher is supposed
1694	trigger next.	1764	to trigger next. This is not the same as the C<offset> argument to
		1765	C<ev_periodic_set>, but indeed works even in interval and manual
		1766	rescheduling modes.
1695		1767
1696	=item ev_tstamp offset [read-write]	1768	=item ev_tstamp offset [read-write]
1697		1769
1698	When repeating, this contains the offset value, otherwise this is the	1770	When repeating, this contains the offset value, otherwise this is the
1699	absolute point in time (the C<at> value passed to C<ev_periodic_set>).	1771	absolute point in time (the C<offset> value passed to C<ev_periodic_set>,
		1772	although libev might modify this value for better numerical stability).
1700		1773
1701	Can be modified any time, but changes only take effect when the periodic	1774	Can be modified any time, but changes only take effect when the periodic
1702	timer fires or C<ev_periodic_again> is being called.	1775	timer fires or C<ev_periodic_again> is being called.
1703		1776
1704	=item ev_tstamp interval [read-write]	1777	=item ev_tstamp interval [read-write]
…		…
1910		1983
1911		1984
1912	=head2 C<ev_stat> - did the file attributes just change?	1985	=head2 C<ev_stat> - did the file attributes just change?
1913		1986
1914	This watches a file system path for attribute changes. That is, it calls	1987	This watches a file system path for attribute changes. That is, it calls
1915	C<stat> regularly (or when the OS says it changed) and sees if it changed	1988	C<stat> on that path in regular intervals (or when the OS says it changed)
1916	compared to the last time, invoking the callback if it did.	1989	and sees if it changed compared to the last time, invoking the callback if
		1990	it did.
1917		1991
1918	The path does not need to exist: changing from "path exists" to "path does	1992	The path does not need to exist: changing from "path exists" to "path does
1919	not exist" is a status change like any other. The condition "path does	1993	not exist" is a status change like any other. The condition "path does not
1920	not exist" is signified by the C<st_nlink> field being zero (which is	1994	exist" (or more correctly "path cannot be stat'ed") is signified by the
1921	otherwise always forced to be at least one) and all the other fields of	1995	C<st_nlink> field being zero (which is otherwise always forced to be at
1922	the stat buffer having unspecified contents.	1996	least one) and all the other fields of the stat buffer having unspecified
		1997	contents.
1923		1998
1924	The path I<should> be absolute and I<must not> end in a slash. If it is	1999	The path I<must not> end in a slash or contain special components such as
		2000	C<.> or C<..>. The path I<should> be absolute: If it is relative and
1925	relative and your working directory changes, the behaviour is undefined.	2001	your working directory changes, then the behaviour is undefined.
1926		2002
1927	Since there is no standard kernel interface to do this, the portable	2003	Since there is no portable change notification interface available, the
1928	implementation simply calls C<stat (2)> regularly on the path to see if	2004	portable implementation simply calls C<stat(2)> regularly on the path
1929	it changed somehow. You can specify a recommended polling interval for	2005	to see if it changed somehow. You can specify a recommended polling
1930	this case. If you specify a polling interval of C<0> (highly recommended!)	2006	interval for this case. If you specify a polling interval of C<0> (highly
1931	then a I<suitable, unspecified default> value will be used (which	2007	recommended!) then a I<suitable, unspecified default> value will be used
1932	you can expect to be around five seconds, although this might change	2008	(which you can expect to be around five seconds, although this might
1933	dynamically). Libev will also impose a minimum interval which is currently	2009	change dynamically). Libev will also impose a minimum interval which is
1934	around C<0.1>, but thats usually overkill.	2010	currently around C<0.1>, but that's usually overkill.
1935		2011
1936	This watcher type is not meant for massive numbers of stat watchers,	2012	This watcher type is not meant for massive numbers of stat watchers,
1937	as even with OS-supported change notifications, this can be	2013	as even with OS-supported change notifications, this can be
1938	resource-intensive.	2014	resource-intensive.
1939		2015
1940	At the time of this writing, the only OS-specific interface implemented	2016	At the time of this writing, the only OS-specific interface implemented
1941	is the Linux inotify interface (implementing kqueue support is left as	2017	is the Linux inotify interface (implementing kqueue support is left as an
1942	an exercise for the reader. Note, however, that the author sees no way	2018	exercise for the reader. Note, however, that the author sees no way of
1943	of implementing C<ev_stat> semantics with kqueue).	2019	implementing C<ev_stat> semantics with kqueue, except as a hint).
1944		2020
1945	=head3 ABI Issues (Largefile Support)	2021	=head3 ABI Issues (Largefile Support)
1946		2022
1947	Libev by default (unless the user overrides this) uses the default	2023	Libev by default (unless the user overrides this) uses the default
1948	compilation environment, which means that on systems with large file	2024	compilation environment, which means that on systems with large file
1949	support disabled by default, you get the 32 bit version of the stat	2025	support disabled by default, you get the 32 bit version of the stat
1950	structure. When using the library from programs that change the ABI to	2026	structure. When using the library from programs that change the ABI to
1951	use 64 bit file offsets the programs will fail. In that case you have to	2027	use 64 bit file offsets the programs will fail. In that case you have to
1952	compile libev with the same flags to get binary compatibility. This is	2028	compile libev with the same flags to get binary compatibility. This is
1953	obviously the case with any flags that change the ABI, but the problem is	2029	obviously the case with any flags that change the ABI, but the problem is
1954	most noticeably disabled with ev_stat and large file support.	2030	most noticeably displayed with ev_stat and large file support.
1955		2031
1956	The solution for this is to lobby your distribution maker to make large	2032	The solution for this is to lobby your distribution maker to make large
1957	file interfaces available by default (as e.g. FreeBSD does) and not	2033	file interfaces available by default (as e.g. FreeBSD does) and not
1958	optional. Libev cannot simply switch on large file support because it has	2034	optional. Libev cannot simply switch on large file support because it has
1959	to exchange stat structures with application programs compiled using the	2035	to exchange stat structures with application programs compiled using the
1960	default compilation environment.	2036	default compilation environment.
1961		2037
1962	=head3 Inotify and Kqueue	2038	=head3 Inotify and Kqueue
1963		2039
1964	When C<inotify (7)> support has been compiled into libev (generally	2040	When C<inotify (7)> support has been compiled into libev and present at
1965	only available with Linux 2.6.25 or above due to bugs in earlier	2041	runtime, it will be used to speed up change detection where possible. The
1966	implementations) and present at runtime, it will be used to speed up	2042	inotify descriptor will be created lazily when the first C<ev_stat>
1967	change detection where possible. The inotify descriptor will be created	2043	watcher is being started.
1968	lazily when the first C<ev_stat> watcher is being started.
1969		2044
1970	Inotify presence does not change the semantics of C<ev_stat> watchers	2045	Inotify presence does not change the semantics of C<ev_stat> watchers
1971	except that changes might be detected earlier, and in some cases, to avoid	2046	except that changes might be detected earlier, and in some cases, to avoid
1972	making regular C<stat> calls. Even in the presence of inotify support	2047	making regular C<stat> calls. Even in the presence of inotify support
1973	there are many cases where libev has to resort to regular C<stat> polling,	2048	there are many cases where libev has to resort to regular C<stat> polling,
1974	but as long as the path exists, libev usually gets away without polling.	2049	but as long as kernel 2.6.25 or newer is used (2.6.24 and older have too
		2050	many bugs), the path exists (i.e. stat succeeds), and the path resides on
		2051	a local filesystem (libev currently assumes only ext2/3, jfs, reiserfs and
		2052	xfs are fully working) libev usually gets away without polling.
1975		2053
1976	There is no support for kqueue, as apparently it cannot be used to	2054	There is no support for kqueue, as apparently it cannot be used to
1977	implement this functionality, due to the requirement of having a file	2055	implement this functionality, due to the requirement of having a file
1978	descriptor open on the object at all times, and detecting renames, unlinks	2056	descriptor open on the object at all times, and detecting renames, unlinks
1979	etc. is difficult.	2057	etc. is difficult.
1980		2058
		2059	=head3 C<stat ()> is a synchronous operation
		2060
		2061	Libev doesn't normally do any kind of I/O itself, and so is not blocking
		2062	the process. The exception are C<ev_stat> watchers - those call C<stat
		2063	()>, which is a synchronous operation.
		2064
		2065	For local paths, this usually doesn't matter: unless the system is very
		2066	busy or the intervals between stat's are large, a stat call will be fast,
		2067	as the path data is usually in memory already (except when starting the
		2068	watcher).
		2069
		2070	For networked file systems, calling C<stat ()> can block an indefinite
		2071	time due to network issues, and even under good conditions, a stat call
		2072	often takes multiple milliseconds.
		2073
		2074	Therefore, it is best to avoid using C<ev_stat> watchers on networked
		2075	paths, although this is fully supported by libev.
		2076
1981	=head3 The special problem of stat time resolution	2077	=head3 The special problem of stat time resolution
1982		2078
1983	The C<stat ()> system call only supports full-second resolution portably, and	2079	The C<stat ()> system call only supports full-second resolution portably,
1984	even on systems where the resolution is higher, most file systems still	2080	and even on systems where the resolution is higher, most file systems
1985	only support whole seconds.	2081	still only support whole seconds.
1986		2082
1987	That means that, if the time is the only thing that changes, you can	2083	That means that, if the time is the only thing that changes, you can
1988	easily miss updates: on the first update, C<ev_stat> detects a change and	2084	easily miss updates: on the first update, C<ev_stat> detects a change and
1989	calls your callback, which does something. When there is another update	2085	calls your callback, which does something. When there is another update
1990	within the same second, C<ev_stat> will be unable to detect unless the	2086	within the same second, C<ev_stat> will be unable to detect unless the
…		…
2133		2229
2134	=head3 Watcher-Specific Functions and Data Members	2230	=head3 Watcher-Specific Functions and Data Members
2135		2231
2136	=over 4	2232	=over 4
2137		2233
2138	=item ev_idle_init (ev_signal *, callback)	2234	=item ev_idle_init (ev_idle *, callback)
2139		2235
2140	Initialises and configures the idle watcher - it has no parameters of any	2236	Initialises and configures the idle watcher - it has no parameters of any
2141	kind. There is a C<ev_idle_set> macro, but using it is utterly pointless,	2237	kind. There is a C<ev_idle_set> macro, but using it is utterly pointless,
2142	believe me.	2238	believe me.
2143		2239
…		…
2382	some fds have to be watched and handled very quickly (with low latency),	2478	some fds have to be watched and handled very quickly (with low latency),
2383	and even priorities and idle watchers might have too much overhead. In	2479	and even priorities and idle watchers might have too much overhead. In
2384	this case you would put all the high priority stuff in one loop and all	2480	this case you would put all the high priority stuff in one loop and all
2385	the rest in a second one, and embed the second one in the first.	2481	the rest in a second one, and embed the second one in the first.
2386		2482
2387	As long as the watcher is active, the callback will be invoked every time	2483	As long as the watcher is active, the callback will be invoked every
2388	there might be events pending in the embedded loop. The callback must then	2484	time there might be events pending in the embedded loop. The callback
2389	call C<ev_embed_sweep (mainloop, watcher)> to make a single sweep and invoke	2485	must then call C<ev_embed_sweep (mainloop, watcher)> to make a single
2390	their callbacks (you could also start an idle watcher to give the embedded	2486	sweep and invoke their callbacks (the callback doesn't need to invoke the
2391	loop strictly lower priority for example). You can also set the callback	2487	C<ev_embed_sweep> function directly, it could also start an idle watcher
2392	to C<0>, in which case the embed watcher will automatically execute the	2488	to give the embedded loop strictly lower priority for example).
2393	embedded loop sweep.
2394		2489
2395	As long as the watcher is started it will automatically handle events. The	2490	You can also set the callback to C<0>, in which case the embed watcher
2396	callback will be invoked whenever some events have been handled. You can	2491	will automatically execute the embedded loop sweep whenever necessary.
2397	set the callback to C<0> to avoid having to specify one if you are not
2398	interested in that.
2399		2492
2400	Also, there have not currently been made special provisions for forking:	2493	Fork detection will be handled transparently while the C<ev_embed> watcher
2401	when you fork, you not only have to call C<ev_loop_fork> on both loops,	2494	is active, i.e., the embedded loop will automatically be forked when the
2402	but you will also have to stop and restart any C<ev_embed> watchers	2495	embedding loop forks. In other cases, the user is responsible for calling
2403	yourself - but you can use a fork watcher to handle this automatically,	2496	C<ev_loop_fork> on the embedded loop.
2404	and future versions of libev might do just that.
2405		2497
2406	Unfortunately, not all backends are embeddable: only the ones returned by	2498	Unfortunately, not all backends are embeddable: only the ones returned by
2407	C<ev_embeddable_backends> are, which, unfortunately, does not include any	2499	C<ev_embeddable_backends> are, which, unfortunately, does not include any
2408	portable one.	2500	portable one.
2409		2501
…		…
2629	=over 4	2721	=over 4
2630		2722
2631	=item ev_async_init (ev_async *, callback)	2723	=item ev_async_init (ev_async *, callback)
2632		2724
2633	Initialises and configures the async watcher - it has no parameters of any	2725	Initialises and configures the async watcher - it has no parameters of any
2634	kind. There is a C<ev_asynd_set> macro, but using it is utterly pointless,	2726	kind. There is a C<ev_async_set> macro, but using it is utterly pointless,
2635	trust me.	2727	trust me.
2636		2728
2637	=item ev_async_send (loop, ev_async *)	2729	=item ev_async_send (loop, ev_async *)
2638		2730
2639	Sends/signals/activates the given C<ev_async> watcher, that is, feeds	2731	Sends/signals/activates the given C<ev_async> watcher, that is, feeds
2640	an C<EV_ASYNC> event on the watcher into the event loop. Unlike	2732	an C<EV_ASYNC> event on the watcher into the event loop. Unlike
2641	C<ev_feed_event>, this call is safe to do from other threads, signal or	2733	C<ev_feed_event>, this call is safe to do from other threads, signal or
2642	similar contexts (see the discussion of C<EV_ATOMIC_T> in the embedding	2734	similar contexts (see the discussion of C<EV_ATOMIC_T> in the embedding
2643	section below on what exactly this means).	2735	section below on what exactly this means).
2644		2736
		2737	Note that, as with other watchers in libev, multiple events might get
		2738	compressed into a single callback invocation (another way to look at this
		2739	is that C<ev_async> watchers are level-triggered, set on C<ev_async_send>,
		2740	reset when the event loop detects that).
		2741
2645	This call incurs the overhead of a system call only once per loop iteration,	2742	This call incurs the overhead of a system call only once per event loop
2646	so while the overhead might be noticeable, it doesn't apply to repeated	2743	iteration, so while the overhead might be noticeable, it doesn't apply to
2647	calls to C<ev_async_send>.	2744	repeated calls to C<ev_async_send> for the same event loop.
2648		2745
2649	=item bool = ev_async_pending (ev_async *)	2746	=item bool = ev_async_pending (ev_async *)
2650		2747
2651	Returns a non-zero value when C<ev_async_send> has been called on the	2748	Returns a non-zero value when C<ev_async_send> has been called on the
2652	watcher but the event has not yet been processed (or even noted) by the	2749	watcher but the event has not yet been processed (or even noted) by the
…		…
2655	C<ev_async_send> sets a flag in the watcher and wakes up the loop. When	2752	C<ev_async_send> sets a flag in the watcher and wakes up the loop. When
2656	the loop iterates next and checks for the watcher to have become active,	2753	the loop iterates next and checks for the watcher to have become active,
2657	it will reset the flag again. C<ev_async_pending> can be used to very	2754	it will reset the flag again. C<ev_async_pending> can be used to very
2658	quickly check whether invoking the loop might be a good idea.	2755	quickly check whether invoking the loop might be a good idea.
2659		2756
2660	Not that this does I<not> check whether the watcher itself is pending, only	2757	Not that this does I<not> check whether the watcher itself is pending,
2661	whether it has been requested to make this watcher pending.	2758	only whether it has been requested to make this watcher pending: there
		2759	is a time window between the event loop checking and resetting the async
		2760	notification, and the callback being invoked.
2662		2761
2663	=back	2762	=back
2664		2763
2665		2764
2666	=head1 OTHER FUNCTIONS	2765	=head1 OTHER FUNCTIONS
…		…
2845		2944
2846	myclass obj;	2945	myclass obj;
2847	ev::io iow;	2946	ev::io iow;
2848	iow.set <myclass, &myclass::io_cb> (&obj);	2947	iow.set <myclass, &myclass::io_cb> (&obj);
2849		2948
		2949	=item w->set (object *)
		2950
		2951	This is an B<experimental> feature that might go away in a future version.
		2952
		2953	This is a variation of a method callback - leaving out the method to call
		2954	will default the method to C<operator ()>, which makes it possible to use
		2955	functor objects without having to manually specify the C<operator ()> all
		2956	the time. Incidentally, you can then also leave out the template argument
		2957	list.
		2958
		2959	The C<operator ()> method prototype must be C<void operator ()(watcher &w,
		2960	int revents)>.
		2961
		2962	See the method-C<set> above for more details.
		2963
		2964	Example: use a functor object as callback.
		2965
		2966	struct myfunctor
		2967	{
		2968	void operator() (ev::io &w, int revents)
		2969	{
		2970	...
		2971	}
		2972	}
		2973
		2974	myfunctor f;
		2975
		2976	ev::io w;
		2977	w.set (&f);
		2978
2850	=item w->set<function> (void *data = 0)	2979	=item w->set<function> (void *data = 0)
2851		2980
2852	Also sets a callback, but uses a static method or plain function as	2981	Also sets a callback, but uses a static method or plain function as
2853	callback. The optional C<data> argument will be stored in the watcher's	2982	callback. The optional C<data> argument will be stored in the watcher's
2854	C<data> member and is free for you to use.	2983	C<data> member and is free for you to use.
…		…
2940	L<http://software.schmorp.de/pkg/EV>.	3069	L<http://software.schmorp.de/pkg/EV>.
2941		3070
2942	=item Python	3071	=item Python
2943		3072
2944	Python bindings can be found at L<http://code.google.com/p/pyev/>. It	3073	Python bindings can be found at L<http://code.google.com/p/pyev/>. It
2945	seems to be quite complete and well-documented. Note, however, that the	3074	seems to be quite complete and well-documented.
2946	patch they require for libev is outright dangerous as it breaks the ABI
2947	for everybody else, and therefore, should never be applied in an installed
2948	libev (if python requires an incompatible ABI then it needs to embed
2949	libev).
2950		3075
2951	=item Ruby	3076	=item Ruby
2952		3077
2953	Tony Arcieri has written a ruby extension that offers access to a subset	3078	Tony Arcieri has written a ruby extension that offers access to a subset
2954	of the libev API and adds file handle abstractions, asynchronous DNS and	3079	of the libev API and adds file handle abstractions, asynchronous DNS and
2955	more on top of it. It can be found via gem servers. Its homepage is at	3080	more on top of it. It can be found via gem servers. Its homepage is at
2956	L<http://rev.rubyforge.org/>.	3081	L<http://rev.rubyforge.org/>.
		3082
		3083	Roger Pack reports that using the link order C<-lws2_32 -lmsvcrt-ruby-190>
		3084	makes rev work even on mingw.
		3085
		3086	=item Haskell
		3087
		3088	A haskell binding to libev is available at
		3089	L<http://hackage.haskell.org/cgi-bin/hackage-scripts/package/hlibev>.
2957		3090
2958	=item D	3091	=item D
2959		3092
2960	Leandro Lucarella has written a D language binding (F<ev.d>) for libev, to	3093	Leandro Lucarella has written a D language binding (F<ev.d>) for libev, to
2961	be found at L<http://proj.llucax.com.ar/wiki/evd>.	3094	be found at L<http://proj.llucax.com.ar/wiki/evd>.
…		…
3072		3205
3073	#define EV_STANDALONE 1	3206	#define EV_STANDALONE 1
3074	#include "ev.h"	3207	#include "ev.h"
3075		3208
3076	Both header files and implementation files can be compiled with a C++	3209	Both header files and implementation files can be compiled with a C++
3077	compiler (at least, thats a stated goal, and breakage will be treated	3210	compiler (at least, that's a stated goal, and breakage will be treated
3078	as a bug).	3211	as a bug).
3079		3212
3080	You need the following files in your source tree, or in a directory	3213	You need the following files in your source tree, or in a directory
3081	in your include path (e.g. in libev/ when using -Ilibev):	3214	in your include path (e.g. in libev/ when using -Ilibev):
3082		3215
…		…
3138	keeps libev from including F<config.h>, and it also defines dummy	3271	keeps libev from including F<config.h>, and it also defines dummy
3139	implementations for some libevent functions (such as logging, which is not	3272	implementations for some libevent functions (such as logging, which is not
3140	supported). It will also not define any of the structs usually found in	3273	supported). It will also not define any of the structs usually found in
3141	F<event.h> that are not directly supported by the libev core alone.	3274	F<event.h> that are not directly supported by the libev core alone.
3142		3275
		3276	In stanbdalone mode, libev will still try to automatically deduce the
		3277	configuration, but has to be more conservative.
		3278
3143	=item EV_USE_MONOTONIC	3279	=item EV_USE_MONOTONIC
3144		3280
3145	If defined to be C<1>, libev will try to detect the availability of the	3281	If defined to be C<1>, libev will try to detect the availability of the
3146	monotonic clock option at both compile time and runtime. Otherwise no use	3282	monotonic clock option at both compile time and runtime. Otherwise no
3147	of the monotonic clock option will be attempted. If you enable this, you	3283	use of the monotonic clock option will be attempted. If you enable this,
3148	usually have to link against librt or something similar. Enabling it when	3284	you usually have to link against librt or something similar. Enabling it
3149	the functionality isn't available is safe, though, although you have	3285	when the functionality isn't available is safe, though, although you have
3150	to make sure you link against any libraries where the C<clock_gettime>	3286	to make sure you link against any libraries where the C<clock_gettime>
3151	function is hiding in (often F<-lrt>).	3287	function is hiding in (often F<-lrt>). See also C<EV_USE_CLOCK_SYSCALL>.
3152		3288
3153	=item EV_USE_REALTIME	3289	=item EV_USE_REALTIME
3154		3290
3155	If defined to be C<1>, libev will try to detect the availability of the	3291	If defined to be C<1>, libev will try to detect the availability of the
3156	real-time clock option at compile time (and assume its availability at	3292	real-time clock option at compile time (and assume its availability
3157	runtime if successful). Otherwise no use of the real-time clock option will	3293	at runtime if successful). Otherwise no use of the real-time clock
3158	be attempted. This effectively replaces C<gettimeofday> by C<clock_get	3294	option will be attempted. This effectively replaces C<gettimeofday>
3159	(CLOCK_REALTIME, ...)> and will not normally affect correctness. See the	3295	by C<clock_get (CLOCK_REALTIME, ...)> and will not normally affect
3160	note about libraries in the description of C<EV_USE_MONOTONIC>, though.	3296	correctness. See the note about libraries in the description of
		3297	C<EV_USE_MONOTONIC>, though. Defaults to the opposite value of
		3298	C<EV_USE_CLOCK_SYSCALL>.
		3299
		3300	=item EV_USE_CLOCK_SYSCALL
		3301
		3302	If defined to be C<1>, libev will try to use a direct syscall instead
		3303	of calling the system-provided C<clock_gettime> function. This option
		3304	exists because on GNU/Linux, C<clock_gettime> is in C<librt>, but C<librt>
		3305	unconditionally pulls in C<libpthread>, slowing down single-threaded
		3306	programs needlessly. Using a direct syscall is slightly slower (in
		3307	theory), because no optimised vdso implementation can be used, but avoids
		3308	the pthread dependency. Defaults to C<1> on GNU/Linux with glibc 2.x or
		3309	higher, as it simplifies linking (no need for C<-lrt>).
3161		3310
3162	=item EV_USE_NANOSLEEP	3311	=item EV_USE_NANOSLEEP
3163		3312
3164	If defined to be C<1>, libev will assume that C<nanosleep ()> is available	3313	If defined to be C<1>, libev will assume that C<nanosleep ()> is available
3165	and will use it for delays. Otherwise it will use C<select ()>.	3314	and will use it for delays. Otherwise it will use C<select ()>.
…		…
3181		3330
3182	=item EV_SELECT_USE_FD_SET	3331	=item EV_SELECT_USE_FD_SET
3183		3332
3184	If defined to C<1>, then the select backend will use the system C<fd_set>	3333	If defined to C<1>, then the select backend will use the system C<fd_set>
3185	structure. This is useful if libev doesn't compile due to a missing	3334	structure. This is useful if libev doesn't compile due to a missing
3186	C<NFDBITS> or C<fd_mask> definition or it mis-guesses the bitset layout on	3335	C<NFDBITS> or C<fd_mask> definition or it mis-guesses the bitset layout
3187	exotic systems. This usually limits the range of file descriptors to some	3336	on exotic systems. This usually limits the range of file descriptors to
3188	low limit such as 1024 or might have other limitations (winsocket only	3337	some low limit such as 1024 or might have other limitations (winsocket
3189	allows 64 sockets). The C<FD_SETSIZE> macro, set before compilation, might	3338	only allows 64 sockets). The C<FD_SETSIZE> macro, set before compilation,
3190	influence the size of the C<fd_set> used.	3339	configures the maximum size of the C<fd_set>.
3191		3340
3192	=item EV_SELECT_IS_WINSOCKET	3341	=item EV_SELECT_IS_WINSOCKET
3193		3342
3194	When defined to C<1>, the select backend will assume that	3343	When defined to C<1>, the select backend will assume that
3195	select/socket/connect etc. don't understand file descriptors but	3344	select/socket/connect etc. don't understand file descriptors but
…		…
3554	loop, as long as you don't confuse yourself). The only exception is that	3703	loop, as long as you don't confuse yourself). The only exception is that
3555	you must not do this from C<ev_periodic> reschedule callbacks.	3704	you must not do this from C<ev_periodic> reschedule callbacks.
3556		3705
3557	Care has been taken to ensure that libev does not keep local state inside	3706	Care has been taken to ensure that libev does not keep local state inside
3558	C<ev_loop>, and other calls do not usually allow for coroutine switches as	3707	C<ev_loop>, and other calls do not usually allow for coroutine switches as
3559	they do not clal any callbacks.	3708	they do not call any callbacks.
3560		3709
3561	=head2 COMPILER WARNINGS	3710	=head2 COMPILER WARNINGS
3562		3711
3563	Depending on your compiler and compiler settings, you might get no or a	3712	Depending on your compiler and compiler settings, you might get no or a
3564	lot of warnings when compiling libev code. Some people are apparently	3713	lot of warnings when compiling libev code. Some people are apparently
…		…
3598	==2274== definitely lost: 0 bytes in 0 blocks.	3747	==2274== definitely lost: 0 bytes in 0 blocks.
3599	==2274== possibly lost: 0 bytes in 0 blocks.	3748	==2274== possibly lost: 0 bytes in 0 blocks.
3600	==2274== still reachable: 256 bytes in 1 blocks.	3749	==2274== still reachable: 256 bytes in 1 blocks.
3601		3750
3602	Then there is no memory leak, just as memory accounted to global variables	3751	Then there is no memory leak, just as memory accounted to global variables
3603	is not a memleak - the memory is still being refernced, and didn't leak.	3752	is not a memleak - the memory is still being referenced, and didn't leak.
3604		3753
3605	Similarly, under some circumstances, valgrind might report kernel bugs	3754	Similarly, under some circumstances, valgrind might report kernel bugs
3606	as if it were a bug in libev (e.g. in realloc or in the poll backend,	3755	as if it were a bug in libev (e.g. in realloc or in the poll backend,
3607	although an acceptable workaround has been found here), or it might be	3756	although an acceptable workaround has been found here), or it might be
3608	confused.	3757	confused.
…		…
3846	=back	3995	=back
3847		3996
3848		3997
3849	=head1 AUTHOR	3998	=head1 AUTHOR
3850		3999
3851	Marc Lehmann <libev@schmorp.de>.	4000	Marc Lehmann <libev@schmorp.de>, with repeated corrections by Mikael Magnusson.
3852		4001

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Comparing libev/ev.pod (file contents): Revision 1.203 by root, Sun Oct 26 00:52:51 2008 UTC vs. Revision 1.231 by root, Wed Apr 15 19:35:53 2009 UTC

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Comparing libev/ev.pod (file contents):
Revision 1.203 by root, Sun Oct 26 00:52:51 2008 UTC vs.
Revision 1.231 by root, Wed Apr 15 19:35:53 2009 UTC