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

Comparing libev/ev.pod (file contents):
Revision 1.58 by root, Wed Nov 28 11:31:34 2007 UTC vs.
Revision 1.76 by root, Sat Dec 8 15:30:30 2007 UTC

…		…
47		47
48	return 0;	48	return 0;
49	}	49	}
50		50
51	=head1 DESCRIPTION	51	=head1 DESCRIPTION
		52
		53	The newest version of this document is also available as a html-formatted
		54	web page you might find easier to navigate when reading it for the first
		55	time: L<http://cvs.schmorp.de/libev/ev.html>.
52		56
53	Libev is an event loop: you register interest in certain events (such as a	57	Libev is an event loop: you register interest in certain events (such as a
54	file descriptor being readable or a timeout occuring), and it will manage	58	file descriptor being readable or a timeout occuring), and it will manage
55	these event sources and provide your program with events.	59	these event sources and provide your program with events.
56		60
…		…
163	C<ev_embeddable_backends () & ev_supported_backends ()>, likewise for	167	C<ev_embeddable_backends () & ev_supported_backends ()>, likewise for
164	recommended ones.	168	recommended ones.
165		169
166	See the description of C<ev_embed> watchers for more info.	170	See the description of C<ev_embed> watchers for more info.
167		171
168	=item ev_set_allocator (void (cb)(void *ptr, size_t size))	172	=item ev_set_allocator (void (cb)(void *ptr, long size))
169		173
170	Sets the allocation function to use (the prototype and semantics are	174	Sets the allocation function to use (the prototype is similar - the
171	identical to the realloc C function). It is used to allocate and free	175	semantics is identical - to the realloc C function). It is used to
172	memory (no surprises here). If it returns zero when memory needs to be	176	allocate and free memory (no surprises here). If it returns zero when
173	allocated, the library might abort or take some potentially destructive	177	memory needs to be allocated, the library might abort or take some
174	action. The default is your system realloc function.	178	potentially destructive action. The default is your system realloc
		179	function.
175		180
176	You could override this function in high-availability programs to, say,	181	You could override this function in high-availability programs to, say,
177	free some memory if it cannot allocate memory, to use a special allocator,	182	free some memory if it cannot allocate memory, to use a special allocator,
178	or even to sleep a while and retry until some memory is available.	183	or even to sleep a while and retry until some memory is available.
179		184
…		…
265	C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will	270	C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will
266	override the flags completely if it is found in the environment. This is	271	override the flags completely if it is found in the environment. This is
267	useful to try out specific backends to test their performance, or to work	272	useful to try out specific backends to test their performance, or to work
268	around bugs.	273	around bugs.
269		274
		275	=item C<EVFLAG_FORKCHECK>
		276
		277	Instead of calling C<ev_default_fork> or C<ev_loop_fork> manually after
		278	a fork, you can also make libev check for a fork in each iteration by
		279	enabling this flag.
		280
		281	This works by calling C<getpid ()> on every iteration of the loop,
		282	and thus this might slow down your event loop if you do a lot of loop
		283	iterations and little real work, but is usually not noticeable (on my
		284	Linux system for example, C<getpid> is actually a simple 5-insn sequence
		285	without a syscall and thus I<very> fast, but my Linux system also has
		286	C<pthread_atfork> which is even faster).
		287
		288	The big advantage of this flag is that you can forget about fork (and
		289	forget about forgetting to tell libev about forking) when you use this
		290	flag.
		291
		292	This flag setting cannot be overriden or specified in the C<LIBEV_FLAGS>
		293	environment variable.
		294
270	=item C<EVBACKEND_SELECT> (value 1, portable select backend)	295	=item C<EVBACKEND_SELECT> (value 1, portable select backend)
271		296
272	This is your standard select(2) backend. Not I<completely> standard, as	297	This is your standard select(2) backend. Not I<completely> standard, as
273	libev tries to roll its own fd_set with no limits on the number of fds,	298	libev tries to roll its own fd_set with no limits on the number of fds,
274	but if that fails, expect a fairly low limit on the number of fds when	299	but if that fails, expect a fairly low limit on the number of fds when
…		…
408	=item ev_loop_fork (loop)	433	=item ev_loop_fork (loop)
409		434
410	Like C<ev_default_fork>, but acts on an event loop created by	435	Like C<ev_default_fork>, but acts on an event loop created by
411	C<ev_loop_new>. Yes, you have to call this on every allocated event loop	436	C<ev_loop_new>. Yes, you have to call this on every allocated event loop
412	after fork, and how you do this is entirely your own problem.	437	after fork, and how you do this is entirely your own problem.
		438
		439	=item unsigned int ev_loop_count (loop)
		440
		441	Returns the count of loop iterations for the loop, which is identical to
		442	the number of times libev did poll for new events. It starts at C<0> and
		443	happily wraps around with enough iterations.
		444
		445	This value can sometimes be useful as a generation counter of sorts (it
		446	"ticks" the number of loop iterations), as it roughly corresponds with
		447	C<ev_prepare> and C<ev_check> calls.
413		448
414	=item unsigned int ev_backend (loop)	449	=item unsigned int ev_backend (loop)
415		450
416	Returns one of the C<EVBACKEND_*> flags indicating the event backend in	451	Returns one of the C<EVBACKEND_*> flags indicating the event backend in
417	use.	452	use.
…		…
701	=item bool ev_is_pending (ev_TYPE *watcher)	736	=item bool ev_is_pending (ev_TYPE *watcher)
702		737
703	Returns a true value iff the watcher is pending, (i.e. it has outstanding	738	Returns a true value iff the watcher is pending, (i.e. it has outstanding
704	events but its callback has not yet been invoked). As long as a watcher	739	events but its callback has not yet been invoked). As long as a watcher
705	is pending (but not active) you must not call an init function on it (but	740	is pending (but not active) you must not call an init function on it (but
706	C<ev_TYPE_set> is safe) and you must make sure the watcher is available to	741	C<ev_TYPE_set> is safe), you must not change its priority, and you must
707	libev (e.g. you cnanot C<free ()> it).	742	make sure the watcher is available to libev (e.g. you cannot C<free ()>
		743	it).
708		744
709	=item callback ev_cb (ev_TYPE *watcher)	745	=item callback ev_cb (ev_TYPE *watcher)
710		746
711	Returns the callback currently set on the watcher.	747	Returns the callback currently set on the watcher.
712		748
713	=item ev_cb_set (ev_TYPE *watcher, callback)	749	=item ev_cb_set (ev_TYPE *watcher, callback)
714		750
715	Change the callback. You can change the callback at virtually any time	751	Change the callback. You can change the callback at virtually any time
716	(modulo threads).	752	(modulo threads).
		753
		754	=item ev_set_priority (ev_TYPE *watcher, priority)
		755
		756	=item int ev_priority (ev_TYPE *watcher)
		757
		758	Set and query the priority of the watcher. The priority is a small
		759	integer between C<EV_MAXPRI> (default: C<2>) and C<EV_MINPRI>
		760	(default: C<-2>). Pending watchers with higher priority will be invoked
		761	before watchers with lower priority, but priority will not keep watchers
		762	from being executed (except for C<ev_idle> watchers).
		763
		764	This means that priorities are I<only> used for ordering callback
		765	invocation after new events have been received. This is useful, for
		766	example, to reduce latency after idling, or more often, to bind two
		767	watchers on the same event and make sure one is called first.
		768
		769	If you need to suppress invocation when higher priority events are pending
		770	you need to look at C<ev_idle> watchers, which provide this functionality.
		771
		772	You I<must not> change the priority of a watcher as long as it is active or
		773	pending.
		774
		775	The default priority used by watchers when no priority has been set is
		776	always C<0>, which is supposed to not be too high and not be too low :).
		777
		778	Setting a priority outside the range of C<EV_MINPRI> to C<EV_MAXPRI> is
		779	fine, as long as you do not mind that the priority value you query might
		780	or might not have been adjusted to be within valid range.
		781
		782	=item ev_invoke (loop, ev_TYPE *watcher, int revents)
		783
		784	Invoke the C<watcher> with the given C<loop> and C<revents>. Neither
		785	C<loop> nor C<revents> need to be valid as long as the watcher callback
		786	can deal with that fact.
		787
		788	=item int ev_clear_pending (loop, ev_TYPE *watcher)
		789
		790	If the watcher is pending, this function returns clears its pending status
		791	and returns its C<revents> bitset (as if its callback was invoked). If the
		792	watcher isn't pending it does nothing and returns C<0>.
717		793
718	=back	794	=back
719		795
720		796
721	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER	797	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER
…		…
827	it is best to always use non-blocking I/O: An extra C<read>(2) returning	903	it is best to always use non-blocking I/O: An extra C<read>(2) returning
828	C<EAGAIN> is far preferable to a program hanging until some data arrives.	904	C<EAGAIN> is far preferable to a program hanging until some data arrives.
829		905
830	If you cannot run the fd in non-blocking mode (for example you should not	906	If you cannot run the fd in non-blocking mode (for example you should not
831	play around with an Xlib connection), then you have to seperately re-test	907	play around with an Xlib connection), then you have to seperately re-test
832	wether a file descriptor is really ready with a known-to-be good interface	908	whether a file descriptor is really ready with a known-to-be good interface
833	such as poll (fortunately in our Xlib example, Xlib already does this on	909	such as poll (fortunately in our Xlib example, Xlib already does this on
834	its own, so its quite safe to use).	910	its own, so its quite safe to use).
835		911
836	=over 4	912	=over 4
837		913
…		…
915	=item ev_timer_again (loop)	991	=item ev_timer_again (loop)
916		992
917	This will act as if the timer timed out and restart it again if it is	993	This will act as if the timer timed out and restart it again if it is
918	repeating. The exact semantics are:	994	repeating. The exact semantics are:
919		995
		996	If the timer is pending, its pending status is cleared.
		997
920	If the timer is started but nonrepeating, stop it.	998	If the timer is started but nonrepeating, stop it (as if it timed out).
921		999
922	If the timer is repeating, either start it if necessary (with the repeat	1000	If the timer is repeating, either start it if necessary (with the
923	value), or reset the running timer to the repeat value.	1001	C<repeat> value), or reset the running timer to the C<repeat> value.
924		1002
925	This sounds a bit complicated, but here is a useful and typical	1003	This sounds a bit complicated, but here is a useful and typical
926	example: Imagine you have a tcp connection and you want a so-called	1004	example: Imagine you have a tcp connection and you want a so-called idle
927	idle timeout, that is, you want to be called when there have been,	1005	timeout, that is, you want to be called when there have been, say, 60
928	say, 60 seconds of inactivity on the socket. The easiest way to do	1006	seconds of inactivity on the socket. The easiest way to do this is to
929	this is to configure an C<ev_timer> with C<after>=C<repeat>=C<60> and calling	1007	configure an C<ev_timer> with a C<repeat> value of C<60> and then call
930	C<ev_timer_again> each time you successfully read or write some data. If	1008	C<ev_timer_again> each time you successfully read or write some data. If
931	you go into an idle state where you do not expect data to travel on the	1009	you go into an idle state where you do not expect data to travel on the
932	socket, you can stop the timer, and again will automatically restart it if	1010	socket, you can C<ev_timer_stop> the timer, and C<ev_timer_again> will
933	need be.	1011	automatically restart it if need be.
934		1012
935	You can also ignore the C<after> value and C<ev_timer_start> altogether	1013	That means you can ignore the C<after> value and C<ev_timer_start>
936	and only ever use the C<repeat> value:	1014	altogether and only ever use the C<repeat> value and C<ev_timer_again>:
937		1015
938	ev_timer_init (timer, callback, 0., 5.);	1016	ev_timer_init (timer, callback, 0., 5.);
939	ev_timer_again (loop, timer);	1017	ev_timer_again (loop, timer);
940	...	1018	...
941	timer->again = 17.;	1019	timer->again = 17.;
942	ev_timer_again (loop, timer);	1020	ev_timer_again (loop, timer);
943	...	1021	...
944	timer->again = 10.;	1022	timer->again = 10.;
945	ev_timer_again (loop, timer);	1023	ev_timer_again (loop, timer);
946		1024
947	This is more efficient then stopping/starting the timer eahc time you want	1025	This is more slightly efficient then stopping/starting the timer each time
948	to modify its timeout value.	1026	you want to modify its timeout value.
949		1027
950	=item ev_tstamp repeat [read-write]	1028	=item ev_tstamp repeat [read-write]
951		1029
952	The current C<repeat> value. Will be used each time the watcher times out	1030	The current C<repeat> value. Will be used each time the watcher times out
953	or C<ev_timer_again> is called and determines the next timeout (if any),	1031	or C<ev_timer_again> is called and determines the next timeout (if any),
…		…
1221	The path does not need to exist: changing from "path exists" to "path does	1299	The path does not need to exist: changing from "path exists" to "path does
1222	not exist" is a status change like any other. The condition "path does	1300	not exist" is a status change like any other. The condition "path does
1223	not exist" is signified by the C<st_nlink> field being zero (which is	1301	not exist" is signified by the C<st_nlink> field being zero (which is
1224	otherwise always forced to be at least one) and all the other fields of	1302	otherwise always forced to be at least one) and all the other fields of
1225	the stat buffer having unspecified contents.	1303	the stat buffer having unspecified contents.
		1304
		1305	The path I<should> be absolute and I<must not> end in a slash. If it is
		1306	relative and your working directory changes, the behaviour is undefined.
1226		1307
1227	Since there is no standard to do this, the portable implementation simply	1308	Since there is no standard to do this, the portable implementation simply
1228	calls C<stat (2)> regularly on the path to see if it changed somehow. You	1309	calls C<stat (2)> regularly on the path to see if it changed somehow. You
1229	can specify a recommended polling interval for this case. If you specify	1310	can specify a recommended polling interval for this case. If you specify
1230	a polling interval of C<0> (highly recommended!) then a I<suitable,	1311	a polling interval of C<0> (highly recommended!) then a I<suitable,
…		…
1315	ev_stat_start (loop, &passwd);	1396	ev_stat_start (loop, &passwd);
1316		1397
1317		1398
1318	=head2 C<ev_idle> - when you've got nothing better to do...	1399	=head2 C<ev_idle> - when you've got nothing better to do...
1319		1400
1320	Idle watchers trigger events when there are no other events are pending	1401	Idle watchers trigger events when no other events of the same or higher
1321	(prepare, check and other idle watchers do not count). That is, as long	1402	priority are pending (prepare, check and other idle watchers do not
1322	as your process is busy handling sockets or timeouts (or even signals,	1403	count).
1323	imagine) it will not be triggered. But when your process is idle all idle	1404
1324	watchers are being called again and again, once per event loop iteration -	1405	That is, as long as your process is busy handling sockets or timeouts
		1406	(or even signals, imagine) of the same or higher priority it will not be
		1407	triggered. But when your process is idle (or only lower-priority watchers
		1408	are pending), the idle watchers are being called once per event loop
1325	until stopped, that is, or your process receives more events and becomes	1409	iteration - until stopped, that is, or your process receives more events
1326	busy.	1410	and becomes busy again with higher priority stuff.
1327		1411
1328	The most noteworthy effect is that as long as any idle watchers are	1412	The most noteworthy effect is that as long as any idle watchers are
1329	active, the process will not block when waiting for new events.	1413	active, the process will not block when waiting for new events.
1330		1414
1331	Apart from keeping your process non-blocking (which is a useful	1415	Apart from keeping your process non-blocking (which is a useful
…		…
1409	parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set>	1493	parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set>
1410	macros, but using them is utterly, utterly and completely pointless.	1494	macros, but using them is utterly, utterly and completely pointless.
1411		1495
1412	=back	1496	=back
1413		1497
1414	Example: To include a library such as adns, you would add IO watchers	1498	There are a number of principal ways to embed other event loops or modules
1415	and a timeout watcher in a prepare handler, as required by libadns, and	1499	into libev. Here are some ideas on how to include libadns into libev
		1500	(there is a Perl module named C<EV::ADNS> that does this, which you could
		1501	use for an actually working example. Another Perl module named C<EV::Glib>
		1502	embeds a Glib main context into libev, and finally, C<Glib::EV> embeds EV
		1503	into the Glib event loop).
		1504
		1505	Method 1: Add IO watchers and a timeout watcher in a prepare handler,
1416	in a check watcher, destroy them and call into libadns. What follows is	1506	and in a check watcher, destroy them and call into libadns. What follows
1417	pseudo-code only of course:	1507	is pseudo-code only of course. This requires you to either use a low
		1508	priority for the check watcher or use C<ev_clear_pending> explicitly, as
		1509	the callbacks for the IO/timeout watchers might not have been called yet.
1418		1510
1419	static ev_io iow [nfd];	1511	static ev_io iow [nfd];
1420	static ev_timer tw;	1512	static ev_timer tw;
1421		1513
1422	static void	1514	static void
1423	io_cb (ev_loop loop, ev_io w, int revents)	1515	io_cb (ev_loop loop, ev_io w, int revents)
1424	{	1516	{
1425	// set the relevant poll flags
1426	// could also call adns_processreadable etc. here
1427	struct pollfd fd = (struct pollfd )w->data;
1428	if (revents & EV_READ ) fd->revents \|= fd->events & POLLIN;
1429	if (revents & EV_WRITE) fd->revents \|= fd->events & POLLOUT;
1430	}	1517	}
1431		1518
1432	// create io watchers for each fd and a timer before blocking	1519	// create io watchers for each fd and a timer before blocking
1433	static void	1520	static void
1434	adns_prepare_cb (ev_loop loop, ev_prepare w, int revents)	1521	adns_prepare_cb (ev_loop loop, ev_prepare w, int revents)
1435	{	1522	{
1436	int timeout = 3600000;truct pollfd fds [nfd];	1523	int timeout = 3600000;
		1524	struct pollfd fds [nfd];
1437	// actual code will need to loop here and realloc etc.	1525	// actual code will need to loop here and realloc etc.
1438	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));	1526	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));
1439		1527
1440	/* the callback is illegal, but won't be called as we stop during check */	1528	/* the callback is illegal, but won't be called as we stop during check */
1441	ev_timer_init (&tw, 0, timeout * 1e-3);	1529	ev_timer_init (&tw, 0, timeout * 1e-3);
1442	ev_timer_start (loop, &tw);	1530	ev_timer_start (loop, &tw);
1443		1531
1444	// create on ev_io per pollfd	1532	// create one ev_io per pollfd
1445	for (int i = 0; i < nfd; ++i)	1533	for (int i = 0; i < nfd; ++i)
1446	{	1534	{
1447	ev_io_init (iow + i, io_cb, fds [i].fd,	1535	ev_io_init (iow + i, io_cb, fds [i].fd,
1448	((fds [i].events & POLLIN ? EV_READ : 0)	1536	((fds [i].events & POLLIN ? EV_READ : 0)
1449	\| (fds [i].events & POLLOUT ? EV_WRITE : 0)));	1537	\| (fds [i].events & POLLOUT ? EV_WRITE : 0)));
1450		1538
1451	fds [i].revents = 0;	1539	fds [i].revents = 0;
1452	iow [i].data = fds + i;
1453	ev_io_start (loop, iow + i);	1540	ev_io_start (loop, iow + i);
1454	}	1541	}
1455	}	1542	}
1456		1543
1457	// stop all watchers after blocking	1544	// stop all watchers after blocking
…		…
1459	adns_check_cb (ev_loop loop, ev_check w, int revents)	1546	adns_check_cb (ev_loop loop, ev_check w, int revents)
1460	{	1547	{
1461	ev_timer_stop (loop, &tw);	1548	ev_timer_stop (loop, &tw);
1462		1549
1463	for (int i = 0; i < nfd; ++i)	1550	for (int i = 0; i < nfd; ++i)
		1551	{
		1552	// set the relevant poll flags
		1553	// could also call adns_processreadable etc. here
		1554	struct pollfd *fd = fds + i;
		1555	int revents = ev_clear_pending (iow + i);
		1556	if (revents & EV_READ ) fd->revents \|= fd->events & POLLIN;
		1557	if (revents & EV_WRITE) fd->revents \|= fd->events & POLLOUT;
		1558
		1559	// now stop the watcher
1464	ev_io_stop (loop, iow + i);	1560	ev_io_stop (loop, iow + i);
		1561	}
1465		1562
1466	adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));	1563	adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));
		1564	}
		1565
		1566	Method 2: This would be just like method 1, but you run C<adns_afterpoll>
		1567	in the prepare watcher and would dispose of the check watcher.
		1568
		1569	Method 3: If the module to be embedded supports explicit event
		1570	notification (adns does), you can also make use of the actual watcher
		1571	callbacks, and only destroy/create the watchers in the prepare watcher.
		1572
		1573	static void
		1574	timer_cb (EV_P_ ev_timer *w, int revents)
		1575	{
		1576	adns_state ads = (adns_state)w->data;
		1577	update_now (EV_A);
		1578
		1579	adns_processtimeouts (ads, &tv_now);
		1580	}
		1581
		1582	static void
		1583	io_cb (EV_P_ ev_io *w, int revents)
		1584	{
		1585	adns_state ads = (adns_state)w->data;
		1586	update_now (EV_A);
		1587
		1588	if (revents & EV_READ ) adns_processreadable (ads, w->fd, &tv_now);
		1589	if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now);
		1590	}
		1591
		1592	// do not ever call adns_afterpoll
		1593
		1594	Method 4: Do not use a prepare or check watcher because the module you
		1595	want to embed is too inflexible to support it. Instead, youc na override
		1596	their poll function. The drawback with this solution is that the main
		1597	loop is now no longer controllable by EV. The C<Glib::EV> module does
		1598	this.
		1599
		1600	static gint
		1601	event_poll_func (GPollFD *fds, guint nfds, gint timeout)
		1602	{
		1603	int got_events = 0;
		1604
		1605	for (n = 0; n < nfds; ++n)
		1606	// create/start io watcher that sets the relevant bits in fds[n] and increment got_events
		1607
		1608	if (timeout >= 0)
		1609	// create/start timer
		1610
		1611	// poll
		1612	ev_loop (EV_A_ 0);
		1613
		1614	// stop timer again
		1615	if (timeout >= 0)
		1616	ev_timer_stop (EV_A_ &to);
		1617
		1618	// stop io watchers again - their callbacks should have set
		1619	for (n = 0; n < nfds; ++n)
		1620	ev_io_stop (EV_A_ iow [n]);
		1621
		1622	return got_events;
1467	}	1623	}
1468		1624
1469		1625
1470	=head2 C<ev_embed> - when one backend isn't enough...	1626	=head2 C<ev_embed> - when one backend isn't enough...
1471		1627
…		…
1675		1831
1676	To use it,	1832	To use it,
1677		1833
1678	#include <ev++.h>	1834	#include <ev++.h>
1679		1835
1680	(it is not installed by default). This automatically includes F<ev.h>	1836	This automatically includes F<ev.h> and puts all of its definitions (many
1681	and puts all of its definitions (many of them macros) into the global	1837	of them macros) into the global namespace. All C++ specific things are
1682	namespace. All C++ specific things are put into the C<ev> namespace.	1838	put into the C<ev> namespace. It should support all the same embedding
		1839	options as F<ev.h>, most notably C<EV_MULTIPLICITY>.
1683		1840
1684	It should support all the same embedding options as F<ev.h>, most notably	1841	Care has been taken to keep the overhead low. The only data member the C++
1685	C<EV_MULTIPLICITY>.	1842	classes add (compared to plain C-style watchers) is the event loop pointer
		1843	that the watcher is associated with (or no additional members at all if
		1844	you disable C<EV_MULTIPLICITY> when embedding libev).
		1845
		1846	Currently, functions, and static and non-static member functions can be
		1847	used as callbacks. Other types should be easy to add as long as they only
		1848	need one additional pointer for context. If you need support for other
		1849	types of functors please contact the author (preferably after implementing
		1850	it).
1686		1851
1687	Here is a list of things available in the C<ev> namespace:	1852	Here is a list of things available in the C<ev> namespace:
1688		1853
1689	=over 4	1854	=over 4
1690		1855
…		…
1706		1871
1707	All of those classes have these methods:	1872	All of those classes have these methods:
1708		1873
1709	=over 4	1874	=over 4
1710		1875
1711	=item ev::TYPE::TYPE (object , object::method )	1876	=item ev::TYPE::TYPE ()
1712		1877
1713	=item ev::TYPE::TYPE (object , object::method , struct ev_loop *)	1878	=item ev::TYPE::TYPE (struct ev_loop *)
1714		1879
1715	=item ev::TYPE::~TYPE	1880	=item ev::TYPE::~TYPE
1716		1881
1717	The constructor takes a pointer to an object and a method pointer to	1882	The constructor (optionally) takes an event loop to associate the watcher
1718	the event handler callback to call in this class. The constructor calls	1883	with. If it is omitted, it will use C<EV_DEFAULT>.
1719	C<ev_init> for you, which means you have to call the C<set> method	1884
1720	before starting it. If you do not specify a loop then the constructor	1885	The constructor calls C<ev_init> for you, which means you have to call the
1721	automatically associates the default loop with this watcher.	1886	C<set> method before starting it.
		1887
		1888	It will not set a callback, however: You have to call the templated C<set>
		1889	method to set a callback before you can start the watcher.
		1890
		1891	(The reason why you have to use a method is a limitation in C++ which does
		1892	not allow explicit template arguments for constructors).
1722		1893
1723	The destructor automatically stops the watcher if it is active.	1894	The destructor automatically stops the watcher if it is active.
		1895
		1896	=item w->set<class, &class::method> (object *)
		1897
		1898	This method sets the callback method to call. The method has to have a
		1899	signature of C<void (*)(ev_TYPE &, int)>, it receives the watcher as
		1900	first argument and the C<revents> as second. The object must be given as
		1901	parameter and is stored in the C<data> member of the watcher.
		1902
		1903	This method synthesizes efficient thunking code to call your method from
		1904	the C callback that libev requires. If your compiler can inline your
		1905	callback (i.e. it is visible to it at the place of the C<set> call and
		1906	your compiler is good :), then the method will be fully inlined into the
		1907	thunking function, making it as fast as a direct C callback.
		1908
		1909	Example: simple class declaration and watcher initialisation
		1910
		1911	struct myclass
		1912	{
		1913	void io_cb (ev::io &w, int revents) { }
		1914	}
		1915
		1916	myclass obj;
		1917	ev::io iow;
		1918	iow.set <myclass, &myclass::io_cb> (&obj);
		1919
		1920	=item w->set<function> (void *data = 0)
		1921
		1922	Also sets a callback, but uses a static method or plain function as
		1923	callback. The optional C<data> argument will be stored in the watcher's
		1924	C<data> member and is free for you to use.
		1925
		1926	The prototype of the C<function> must be C<void (*)(ev::TYPE &w, int)>.
		1927
		1928	See the method-C<set> above for more details.
		1929
		1930	Example:
		1931
		1932	static void io_cb (ev::io &w, int revents) { }
		1933	iow.set <io_cb> ();
1724		1934
1725	=item w->set (struct ev_loop *)	1935	=item w->set (struct ev_loop *)
1726		1936
1727	Associates a different C<struct ev_loop> with this watcher. You can only	1937	Associates a different C<struct ev_loop> with this watcher. You can only
1728	do this when the watcher is inactive (and not pending either).	1938	do this when the watcher is inactive (and not pending either).
1729		1939
1730	=item w->set ([args])	1940	=item w->set ([args])
1731		1941
1732	Basically the same as C<ev_TYPE_set>, with the same args. Must be	1942	Basically the same as C<ev_TYPE_set>, with the same args. Must be
1733	called at least once. Unlike the C counterpart, an active watcher gets	1943	called at least once. Unlike the C counterpart, an active watcher gets
1734	automatically stopped and restarted.	1944	automatically stopped and restarted when reconfiguring it with this
		1945	method.
1735		1946
1736	=item w->start ()	1947	=item w->start ()
1737		1948
1738	Starts the watcher. Note that there is no C<loop> argument as the	1949	Starts the watcher. Note that there is no C<loop> argument, as the
1739	constructor already takes the loop.	1950	constructor already stores the event loop.
1740		1951
1741	=item w->stop ()	1952	=item w->stop ()
1742		1953
1743	Stops the watcher if it is active. Again, no C<loop> argument.	1954	Stops the watcher if it is active. Again, no C<loop> argument.
1744		1955
…		…
1769		1980
1770	myclass ();	1981	myclass ();
1771	}	1982	}
1772		1983
1773	myclass::myclass (int fd)	1984	myclass::myclass (int fd)
1774	: io (this, &myclass::io_cb),
1775	idle (this, &myclass::idle_cb)
1776	{	1985	{
		1986	io .set <myclass, &myclass::io_cb > (this);
		1987	idle.set <myclass, &myclass::idle_cb> (this);
		1988
1777	io.start (fd, ev::READ);	1989	io.start (fd, ev::READ);
1778	}	1990	}
1779		1991
1780		1992
1781	=head1 MACRO MAGIC	1993	=head1 MACRO MAGIC
1782		1994
1783	Libev can be compiled with a variety of options, the most fundemantal is	1995	Libev can be compiled with a variety of options, the most fundemantal is
1784	C<EV_MULTIPLICITY>. This option determines wether (most) functions and	1996	C<EV_MULTIPLICITY>. This option determines whether (most) functions and
1785	callbacks have an initial C<struct ev_loop *> argument.	1997	callbacks have an initial C<struct ev_loop *> argument.
1786		1998
1787	To make it easier to write programs that cope with either variant, the	1999	To make it easier to write programs that cope with either variant, the
1788	following macros are defined:	2000	following macros are defined:
1789		2001
…		…
1822	Similar to the other two macros, this gives you the value of the default	2034	Similar to the other two macros, this gives you the value of the default
1823	loop, if multiple loops are supported ("ev loop default").	2035	loop, if multiple loops are supported ("ev loop default").
1824		2036
1825	=back	2037	=back
1826		2038
1827	Example: Declare and initialise a check watcher, working regardless of	2039	Example: Declare and initialise a check watcher, utilising the above
1828	wether multiple loops are supported or not.	2040	macros so it will work regardless of whether multiple loops are supported
		2041	or not.
1829		2042
1830	static void	2043	static void
1831	check_cb (EV_P_ ev_timer *w, int revents)	2044	check_cb (EV_P_ ev_timer *w, int revents)
1832	{	2045	{
1833	ev_check_stop (EV_A_ w);	2046	ev_check_stop (EV_A_ w);
…		…
1835		2048
1836	ev_check check;	2049	ev_check check;
1837	ev_check_init (&check, check_cb);	2050	ev_check_init (&check, check_cb);
1838	ev_check_start (EV_DEFAULT_ &check);	2051	ev_check_start (EV_DEFAULT_ &check);
1839	ev_loop (EV_DEFAULT_ 0);	2052	ev_loop (EV_DEFAULT_ 0);
1840
1841		2053
1842	=head1 EMBEDDING	2054	=head1 EMBEDDING
1843		2055
1844	Libev can (and often is) directly embedded into host	2056	Libev can (and often is) directly embedded into host
1845	applications. Examples of applications that embed it include the Deliantra	2057	applications. Examples of applications that embed it include the Deliantra
…		…
1885	ev_vars.h	2097	ev_vars.h
1886	ev_wrap.h	2098	ev_wrap.h
1887		2099
1888	ev_win32.c required on win32 platforms only	2100	ev_win32.c required on win32 platforms only
1889		2101
1890	ev_select.c only when select backend is enabled (which is by default)	2102	ev_select.c only when select backend is enabled (which is enabled by default)
1891	ev_poll.c only when poll backend is enabled (disabled by default)	2103	ev_poll.c only when poll backend is enabled (disabled by default)
1892	ev_epoll.c only when the epoll backend is enabled (disabled by default)	2104	ev_epoll.c only when the epoll backend is enabled (disabled by default)
1893	ev_kqueue.c only when the kqueue backend is enabled (disabled by default)	2105	ev_kqueue.c only when the kqueue backend is enabled (disabled by default)
1894	ev_port.c only when the solaris port backend is enabled (disabled by default)	2106	ev_port.c only when the solaris port backend is enabled (disabled by default)
1895		2107
…		…
2058	will have the C<struct ev_loop *> as first argument, and you can create	2270	will have the C<struct ev_loop *> as first argument, and you can create
2059	additional independent event loops. Otherwise there will be no support	2271	additional independent event loops. Otherwise there will be no support
2060	for multiple event loops and there is no first event loop pointer	2272	for multiple event loops and there is no first event loop pointer
2061	argument. Instead, all functions act on the single default loop.	2273	argument. Instead, all functions act on the single default loop.
2062		2274
		2275	=item EV_MINPRI
		2276
		2277	=item EV_MAXPRI
		2278
		2279	The range of allowed priorities. C<EV_MINPRI> must be smaller or equal to
		2280	C<EV_MAXPRI>, but otherwise there are no non-obvious limitations. You can
		2281	provide for more priorities by overriding those symbols (usually defined
		2282	to be C<-2> and C<2>, respectively).
		2283
		2284	When doing priority-based operations, libev usually has to linearly search
		2285	all the priorities, so having many of them (hundreds) uses a lot of space
		2286	and time, so using the defaults of five priorities (-2 .. +2) is usually
		2287	fine.
		2288
		2289	If your embedding app does not need any priorities, defining these both to
		2290	C<0> will save some memory and cpu.
		2291
2063	=item EV_PERIODIC_ENABLE	2292	=item EV_PERIODIC_ENABLE
2064		2293
2065	If undefined or defined to be C<1>, then periodic timers are supported. If	2294	If undefined or defined to be C<1>, then periodic timers are supported. If
		2295	defined to be C<0>, then they are not. Disabling them saves a few kB of
		2296	code.
		2297
		2298	=item EV_IDLE_ENABLE
		2299
		2300	If undefined or defined to be C<1>, then idle watchers are supported. If
2066	defined to be C<0>, then they are not. Disabling them saves a few kB of	2301	defined to be C<0>, then they are not. Disabling them saves a few kB of
2067	code.	2302	code.
2068		2303
2069	=item EV_EMBED_ENABLE	2304	=item EV_EMBED_ENABLE
2070		2305
…		…
2137	interface) and F<EV.xs> (implementation) files. Only the F<EV.xs> file	2372	interface) and F<EV.xs> (implementation) files. Only the F<EV.xs> file
2138	will be compiled. It is pretty complex because it provides its own header	2373	will be compiled. It is pretty complex because it provides its own header
2139	file.	2374	file.
2140		2375
2141	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file	2376	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file
2142	that everybody includes and which overrides some autoconf choices:	2377	that everybody includes and which overrides some configure choices:
2143		2378
		2379	#define EV_MINIMAL 1
2144	#define EV_USE_POLL 0	2380	#define EV_USE_POLL 0
2145	#define EV_MULTIPLICITY 0	2381	#define EV_MULTIPLICITY 0
2146	#define EV_PERIODICS 0	2382	#define EV_PERIODIC_ENABLE 0
		2383	#define EV_STAT_ENABLE 0
		2384	#define EV_FORK_ENABLE 0
2147	#define EV_CONFIG_H <config.h>	2385	#define EV_CONFIG_H <config.h>
		2386	#define EV_MINPRI 0
		2387	#define EV_MAXPRI 0
2148		2388
2149	#include "ev++.h"	2389	#include "ev++.h"
2150		2390
2151	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:	2391	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:
2152		2392
…		…
2158		2398
2159	In this section the complexities of (many of) the algorithms used inside	2399	In this section the complexities of (many of) the algorithms used inside
2160	libev will be explained. For complexity discussions about backends see the	2400	libev will be explained. For complexity discussions about backends see the
2161	documentation for C<ev_default_init>.	2401	documentation for C<ev_default_init>.
2162		2402
		2403	All of the following are about amortised time: If an array needs to be
		2404	extended, libev needs to realloc and move the whole array, but this
		2405	happens asymptotically never with higher number of elements, so O(1) might
		2406	mean it might do a lengthy realloc operation in rare cases, but on average
		2407	it is much faster and asymptotically approaches constant time.
		2408
2163	=over 4	2409	=over 4
2164		2410
2165	=item Starting and stopping timer/periodic watchers: O(log skipped_other_timers)	2411	=item Starting and stopping timer/periodic watchers: O(log skipped_other_timers)
2166		2412
		2413	This means that, when you have a watcher that triggers in one hour and
		2414	there are 100 watchers that would trigger before that then inserting will
		2415	have to skip those 100 watchers.
		2416
2167	=item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)	2417	=item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)
2168		2418
		2419	That means that for changing a timer costs less than removing/adding them
		2420	as only the relative motion in the event queue has to be paid for.
		2421
2169	=item Starting io/check/prepare/idle/signal/child watchers: O(1)	2422	=item Starting io/check/prepare/idle/signal/child watchers: O(1)
2170		2423
		2424	These just add the watcher into an array or at the head of a list.
2171	=item Stopping check/prepare/idle watchers: O(1)	2425	=item Stopping check/prepare/idle watchers: O(1)
2172		2426
2173	=item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))	2427	=item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))
2174		2428
		2429	These watchers are stored in lists then need to be walked to find the
		2430	correct watcher to remove. The lists are usually short (you don't usually
		2431	have many watchers waiting for the same fd or signal).
		2432
2175	=item Finding the next timer per loop iteration: O(1)	2433	=item Finding the next timer per loop iteration: O(1)
2176		2434
2177	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)	2435	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)
2178		2436
		2437	A change means an I/O watcher gets started or stopped, which requires
		2438	libev to recalculate its status (and possibly tell the kernel).
		2439
2179	=item Activating one watcher: O(1)	2440	=item Activating one watcher: O(1)
2180		2441
		2442	=item Priority handling: O(number_of_priorities)
		2443
		2444	Priorities are implemented by allocating some space for each
		2445	priority. When doing priority-based operations, libev usually has to
		2446	linearly search all the priorities.
		2447
2181	=back	2448	=back
2182		2449
2183		2450
2184	=head1 AUTHOR	2451	=head1 AUTHOR
2185		2452

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Comparing libev/ev.pod (file contents): Revision 1.58 by root, Wed Nov 28 11:31:34 2007 UTC vs. Revision 1.76 by root, Sat Dec 8 15:30:30 2007 UTC

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Comparing libev/ev.pod (file contents):
Revision 1.58 by root, Wed Nov 28 11:31:34 2007 UTC vs.
Revision 1.76 by root, Sat Dec 8 15:30:30 2007 UTC