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

Comparing libev/ev.pod (file contents):
Revision 1.54 by root, Tue Nov 27 20:26:51 2007 UTC vs.
Revision 1.73 by root, Sat Dec 8 03:53:36 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
…		…
63	details of the event, and then hand it over to libev by I<starting> the	67	details of the event, and then hand it over to libev by I<starting> the
64	watcher.	68	watcher.
65		69
66	=head1 FEATURES	70	=head1 FEATURES
67		71
68	Libev supports C<select>, C<poll>, the linux-specific C<epoll>, the	72	Libev supports C<select>, C<poll>, the Linux-specific C<epoll>, the
69	bsd-specific C<kqueue> and the solaris-specific event port mechanisms	73	BSD-specific C<kqueue> and the Solaris-specific event port mechanisms
70	for file descriptor events (C<ev_io>), relative timers (C<ev_timer>),	74	for file descriptor events (C<ev_io>), the Linux C<inotify> interface
		75	(for C<ev_stat>), relative timers (C<ev_timer>), absolute timers
71	absolute timers with customised rescheduling (C<ev_periodic>), synchronous	76	with customised rescheduling (C<ev_periodic>), synchronous signals
72	signals (C<ev_signal>), process status change events (C<ev_child>), and	77	(C<ev_signal>), process status change events (C<ev_child>), and event
73	event watchers dealing with the event loop mechanism itself (C<ev_idle>,	78	watchers dealing with the event loop mechanism itself (C<ev_idle>,
74	C<ev_embed>, C<ev_prepare> and C<ev_check> watchers) as well as	79	C<ev_embed>, C<ev_prepare> and C<ev_check> watchers) as well as
75	file watchers (C<ev_stat>) and even limited support for fork events	80	file watchers (C<ev_stat>) and even limited support for fork events
76	(C<ev_fork>).	81	(C<ev_fork>).
77		82
78	It also is quite fast (see this	83	It also is quite fast (see this
…		…
162	C<ev_embeddable_backends () & ev_supported_backends ()>, likewise for	167	C<ev_embeddable_backends () & ev_supported_backends ()>, likewise for
163	recommended ones.	168	recommended ones.
164		169
165	See the description of C<ev_embed> watchers for more info.	170	See the description of C<ev_embed> watchers for more info.
166		171
167	=item ev_set_allocator (void (cb)(void *ptr, size_t size))	172	=item ev_set_allocator (void (cb)(void *ptr, long size))
168		173
169	Sets the allocation function to use (the prototype and semantics are	174	Sets the allocation function to use (the prototype is similar - the
170	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
171	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
172	allocated, the library might abort or take some potentially destructive	177	memory needs to be allocated, the library might abort or take some
173	action. The default is your system realloc function.	178	potentially destructive action. The default is your system realloc
		179	function.
174		180
175	You could override this function in high-availability programs to, say,	181	You could override this function in high-availability programs to, say,
176	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,
177	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.
178		184
…		…
264	C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will	270	C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will
265	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
266	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
267	around bugs.	273	around bugs.
268		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
269	=item C<EVBACKEND_SELECT> (value 1, portable select backend)	295	=item C<EVBACKEND_SELECT> (value 1, portable select backend)
270		296
271	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
272	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,
273	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
…		…
407	=item ev_loop_fork (loop)	433	=item ev_loop_fork (loop)
408		434
409	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
410	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
411	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.
412		448
413	=item unsigned int ev_backend (loop)	449	=item unsigned int ev_backend (loop)
414		450
415	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
416	use.	452	use.
…		…
700	=item bool ev_is_pending (ev_TYPE *watcher)	736	=item bool ev_is_pending (ev_TYPE *watcher)
701		737
702	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
703	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
704	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
705	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
706	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).
707		744
708	=item callback = ev_cb (ev_TYPE *watcher)	745	=item callback ev_cb (ev_TYPE *watcher)
709		746
710	Returns the callback currently set on the watcher.	747	Returns the callback currently set on the watcher.
711		748
712	=item ev_cb_set (ev_TYPE *watcher, callback)	749	=item ev_cb_set (ev_TYPE *watcher, callback)
713		750
714	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
715	(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.
716		781
717	=back	782	=back
718		783
719		784
720	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER	785	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER
…		…
741	{	806	{
742	struct my_io w = (struct my_io )w_;	807	struct my_io w = (struct my_io )w_;
743	...	808	...
744	}	809	}
745		810
746	More interesting and less C-conformant ways of catsing your callback type	811	More interesting and less C-conformant ways of casting your callback type
747	have been omitted....	812	instead have been omitted.
		813
		814	Another common scenario is having some data structure with multiple
		815	watchers:
		816
		817	struct my_biggy
		818	{
		819	int some_data;
		820	ev_timer t1;
		821	ev_timer t2;
		822	}
		823
		824	In this case getting the pointer to C<my_biggy> is a bit more complicated,
		825	you need to use C<offsetof>:
		826
		827	#include <stddef.h>
		828
		829	static void
		830	t1_cb (EV_P_ struct ev_timer *w, int revents)
		831	{
		832	struct my_biggy big = (struct my_biggy *
		833	(((char *)w) - offsetof (struct my_biggy, t1));
		834	}
		835
		836	static void
		837	t2_cb (EV_P_ struct ev_timer *w, int revents)
		838	{
		839	struct my_biggy big = (struct my_biggy *
		840	(((char *)w) - offsetof (struct my_biggy, t2));
		841	}
748		842
749		843
750	=head1 WATCHER TYPES	844	=head1 WATCHER TYPES
751		845
752	This section describes each watcher in detail, but will not repeat	846	This section describes each watcher in detail, but will not repeat
…		…
797	it is best to always use non-blocking I/O: An extra C<read>(2) returning	891	it is best to always use non-blocking I/O: An extra C<read>(2) returning
798	C<EAGAIN> is far preferable to a program hanging until some data arrives.	892	C<EAGAIN> is far preferable to a program hanging until some data arrives.
799		893
800	If you cannot run the fd in non-blocking mode (for example you should not	894	If you cannot run the fd in non-blocking mode (for example you should not
801	play around with an Xlib connection), then you have to seperately re-test	895	play around with an Xlib connection), then you have to seperately re-test
802	wether a file descriptor is really ready with a known-to-be good interface	896	whether a file descriptor is really ready with a known-to-be good interface
803	such as poll (fortunately in our Xlib example, Xlib already does this on	897	such as poll (fortunately in our Xlib example, Xlib already does this on
804	its own, so its quite safe to use).	898	its own, so its quite safe to use).
805		899
806	=over 4	900	=over 4
807		901
…		…
885	=item ev_timer_again (loop)	979	=item ev_timer_again (loop)
886		980
887	This will act as if the timer timed out and restart it again if it is	981	This will act as if the timer timed out and restart it again if it is
888	repeating. The exact semantics are:	982	repeating. The exact semantics are:
889		983
		984	If the timer is pending, its pending status is cleared.
		985
890	If the timer is started but nonrepeating, stop it.	986	If the timer is started but nonrepeating, stop it (as if it timed out).
891		987
892	If the timer is repeating, either start it if necessary (with the repeat	988	If the timer is repeating, either start it if necessary (with the
893	value), or reset the running timer to the repeat value.	989	C<repeat> value), or reset the running timer to the C<repeat> value.
894		990
895	This sounds a bit complicated, but here is a useful and typical	991	This sounds a bit complicated, but here is a useful and typical
896	example: Imagine you have a tcp connection and you want a so-called	992	example: Imagine you have a tcp connection and you want a so-called idle
897	idle timeout, that is, you want to be called when there have been,	993	timeout, that is, you want to be called when there have been, say, 60
898	say, 60 seconds of inactivity on the socket. The easiest way to do	994	seconds of inactivity on the socket. The easiest way to do this is to
899	this is to configure an C<ev_timer> with C<after>=C<repeat>=C<60> and calling	995	configure an C<ev_timer> with a C<repeat> value of C<60> and then call
900	C<ev_timer_again> each time you successfully read or write some data. If	996	C<ev_timer_again> each time you successfully read or write some data. If
901	you go into an idle state where you do not expect data to travel on the	997	you go into an idle state where you do not expect data to travel on the
902	socket, you can stop the timer, and again will automatically restart it if	998	socket, you can C<ev_timer_stop> the timer, and C<ev_timer_again> will
903	need be.	999	automatically restart it if need be.
904		1000
905	You can also ignore the C<after> value and C<ev_timer_start> altogether	1001	That means you can ignore the C<after> value and C<ev_timer_start>
906	and only ever use the C<repeat> value:	1002	altogether and only ever use the C<repeat> value and C<ev_timer_again>:
907		1003
908	ev_timer_init (timer, callback, 0., 5.);	1004	ev_timer_init (timer, callback, 0., 5.);
909	ev_timer_again (loop, timer);	1005	ev_timer_again (loop, timer);
910	...	1006	...
911	timer->again = 17.;	1007	timer->again = 17.;
912	ev_timer_again (loop, timer);	1008	ev_timer_again (loop, timer);
913	...	1009	...
914	timer->again = 10.;	1010	timer->again = 10.;
915	ev_timer_again (loop, timer);	1011	ev_timer_again (loop, timer);
916		1012
917	This is more efficient then stopping/starting the timer eahc time you want	1013	This is more slightly efficient then stopping/starting the timer each time
918	to modify its timeout value.	1014	you want to modify its timeout value.
919		1015
920	=item ev_tstamp repeat [read-write]	1016	=item ev_tstamp repeat [read-write]
921		1017
922	The current C<repeat> value. Will be used each time the watcher times out	1018	The current C<repeat> value. Will be used each time the watcher times out
923	or C<ev_timer_again> is called and determines the next timeout (if any),	1019	or C<ev_timer_again> is called and determines the next timeout (if any),
…		…
1192	not exist" is a status change like any other. The condition "path does	1288	not exist" is a status change like any other. The condition "path does
1193	not exist" is signified by the C<st_nlink> field being zero (which is	1289	not exist" is signified by the C<st_nlink> field being zero (which is
1194	otherwise always forced to be at least one) and all the other fields of	1290	otherwise always forced to be at least one) and all the other fields of
1195	the stat buffer having unspecified contents.	1291	the stat buffer having unspecified contents.
1196		1292
		1293	The path I<should> be absolute and I<must not> end in a slash. If it is
		1294	relative and your working directory changes, the behaviour is undefined.
		1295
1197	Since there is no standard to do this, the portable implementation simply	1296	Since there is no standard to do this, the portable implementation simply
1198	calls C<stat (2)> regulalry on the path to see if it changed somehow. You	1297	calls C<stat (2)> regularly on the path to see if it changed somehow. You
1199	can specify a recommended polling interval for this case. If you specify	1298	can specify a recommended polling interval for this case. If you specify
1200	a polling interval of C<0> (highly recommended!) then a I<suitable,	1299	a polling interval of C<0> (highly recommended!) then a I<suitable,
1201	unspecified default> value will be used (which you can expect to be around	1300	unspecified default> value will be used (which you can expect to be around
1202	five seconds, although this might change dynamically). Libev will also	1301	five seconds, although this might change dynamically). Libev will also
1203	impose a minimum interval which is currently around C<0.1>, but thats	1302	impose a minimum interval which is currently around C<0.1>, but thats
…		…
1205		1304
1206	This watcher type is not meant for massive numbers of stat watchers,	1305	This watcher type is not meant for massive numbers of stat watchers,
1207	as even with OS-supported change notifications, this can be	1306	as even with OS-supported change notifications, this can be
1208	resource-intensive.	1307	resource-intensive.
1209		1308
1210	At the time of this writing, no specific OS backends are implemented, but	1309	At the time of this writing, only the Linux inotify interface is
1211	if demand increases, at least a kqueue and inotify backend will be added.	1310	implemented (implementing kqueue support is left as an exercise for the
		1311	reader). Inotify will be used to give hints only and should not change the
		1312	semantics of C<ev_stat> watchers, which means that libev sometimes needs
		1313	to fall back to regular polling again even with inotify, but changes are
		1314	usually detected immediately, and if the file exists there will be no
		1315	polling.
1212		1316
1213	=over 4	1317	=over 4
1214		1318
1215	=item ev_stat_init (ev_stat , callback, const char path, ev_tstamp interval)	1319	=item ev_stat_init (ev_stat , callback, const char path, ev_tstamp interval)
1216		1320
…		…
1280	ev_stat_start (loop, &passwd);	1384	ev_stat_start (loop, &passwd);
1281		1385
1282		1386
1283	=head2 C<ev_idle> - when you've got nothing better to do...	1387	=head2 C<ev_idle> - when you've got nothing better to do...
1284		1388
1285	Idle watchers trigger events when there are no other events are pending	1389	Idle watchers trigger events when no other events of the same or higher
1286	(prepare, check and other idle watchers do not count). That is, as long	1390	priority are pending (prepare, check and other idle watchers do not
1287	as your process is busy handling sockets or timeouts (or even signals,	1391	count).
1288	imagine) it will not be triggered. But when your process is idle all idle	1392
1289	watchers are being called again and again, once per event loop iteration -	1393	That is, as long as your process is busy handling sockets or timeouts
		1394	(or even signals, imagine) of the same or higher priority it will not be
		1395	triggered. But when your process is idle (or only lower-priority watchers
		1396	are pending), the idle watchers are being called once per event loop
1290	until stopped, that is, or your process receives more events and becomes	1397	iteration - until stopped, that is, or your process receives more events
1291	busy.	1398	and becomes busy again with higher priority stuff.
1292		1399
1293	The most noteworthy effect is that as long as any idle watchers are	1400	The most noteworthy effect is that as long as any idle watchers are
1294	active, the process will not block when waiting for new events.	1401	active, the process will not block when waiting for new events.
1295		1402
1296	Apart from keeping your process non-blocking (which is a useful	1403	Apart from keeping your process non-blocking (which is a useful
…		…
1396		1503
1397	// create io watchers for each fd and a timer before blocking	1504	// create io watchers for each fd and a timer before blocking
1398	static void	1505	static void
1399	adns_prepare_cb (ev_loop loop, ev_prepare w, int revents)	1506	adns_prepare_cb (ev_loop loop, ev_prepare w, int revents)
1400	{	1507	{
1401	int timeout = 3600000;truct pollfd fds [nfd];	1508	int timeout = 3600000;
		1509	struct pollfd fds [nfd];
1402	// actual code will need to loop here and realloc etc.	1510	// actual code will need to loop here and realloc etc.
1403	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));	1511	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));
1404		1512
1405	/* the callback is illegal, but won't be called as we stop during check */	1513	/* the callback is illegal, but won't be called as we stop during check */
1406	ev_timer_init (&tw, 0, timeout * 1e-3);	1514	ev_timer_init (&tw, 0, timeout * 1e-3);
…		…
1640		1748
1641	To use it,	1749	To use it,
1642		1750
1643	#include <ev++.h>	1751	#include <ev++.h>
1644		1752
1645	(it is not installed by default). This automatically includes F<ev.h>	1753	This automatically includes F<ev.h> and puts all of its definitions (many
1646	and puts all of its definitions (many of them macros) into the global	1754	of them macros) into the global namespace. All C++ specific things are
1647	namespace. All C++ specific things are put into the C<ev> namespace.	1755	put into the C<ev> namespace. It should support all the same embedding
		1756	options as F<ev.h>, most notably C<EV_MULTIPLICITY>.
1648		1757
1649	It should support all the same embedding options as F<ev.h>, most notably	1758	Care has been taken to keep the overhead low. The only data member the C++
1650	C<EV_MULTIPLICITY>.	1759	classes add (compared to plain C-style watchers) is the event loop pointer
		1760	that the watcher is associated with (or no additional members at all if
		1761	you disable C<EV_MULTIPLICITY> when embedding libev).
		1762
		1763	Currently, functions, and static and non-static member functions can be
		1764	used as callbacks. Other types should be easy to add as long as they only
		1765	need one additional pointer for context. If you need support for other
		1766	types of functors please contact the author (preferably after implementing
		1767	it).
1651		1768
1652	Here is a list of things available in the C<ev> namespace:	1769	Here is a list of things available in the C<ev> namespace:
1653		1770
1654	=over 4	1771	=over 4
1655		1772
…		…
1671		1788
1672	All of those classes have these methods:	1789	All of those classes have these methods:
1673		1790
1674	=over 4	1791	=over 4
1675		1792
1676	=item ev::TYPE::TYPE (object , object::method )	1793	=item ev::TYPE::TYPE ()
1677		1794
1678	=item ev::TYPE::TYPE (object , object::method , struct ev_loop *)	1795	=item ev::TYPE::TYPE (struct ev_loop *)
1679		1796
1680	=item ev::TYPE::~TYPE	1797	=item ev::TYPE::~TYPE
1681		1798
1682	The constructor takes a pointer to an object and a method pointer to	1799	The constructor (optionally) takes an event loop to associate the watcher
1683	the event handler callback to call in this class. The constructor calls	1800	with. If it is omitted, it will use C<EV_DEFAULT>.
1684	C<ev_init> for you, which means you have to call the C<set> method	1801
1685	before starting it. If you do not specify a loop then the constructor	1802	The constructor calls C<ev_init> for you, which means you have to call the
1686	automatically associates the default loop with this watcher.	1803	C<set> method before starting it.
		1804
		1805	It will not set a callback, however: You have to call the templated C<set>
		1806	method to set a callback before you can start the watcher.
		1807
		1808	(The reason why you have to use a method is a limitation in C++ which does
		1809	not allow explicit template arguments for constructors).
1687		1810
1688	The destructor automatically stops the watcher if it is active.	1811	The destructor automatically stops the watcher if it is active.
		1812
		1813	=item w->set<class, &class::method> (object *)
		1814
		1815	This method sets the callback method to call. The method has to have a
		1816	signature of C<void (*)(ev_TYPE &, int)>, it receives the watcher as
		1817	first argument and the C<revents> as second. The object must be given as
		1818	parameter and is stored in the C<data> member of the watcher.
		1819
		1820	This method synthesizes efficient thunking code to call your method from
		1821	the C callback that libev requires. If your compiler can inline your
		1822	callback (i.e. it is visible to it at the place of the C<set> call and
		1823	your compiler is good :), then the method will be fully inlined into the
		1824	thunking function, making it as fast as a direct C callback.
		1825
		1826	Example: simple class declaration and watcher initialisation
		1827
		1828	struct myclass
		1829	{
		1830	void io_cb (ev::io &w, int revents) { }
		1831	}
		1832
		1833	myclass obj;
		1834	ev::io iow;
		1835	iow.set <myclass, &myclass::io_cb> (&obj);
		1836
		1837	=item w->set (void (function)(watcher &w, int), void data = 0)
		1838
		1839	Also sets a callback, but uses a static method or plain function as
		1840	callback. The optional C<data> argument will be stored in the watcher's
		1841	C<data> member and is free for you to use.
		1842
		1843	See the method-C<set> above for more details.
1689		1844
1690	=item w->set (struct ev_loop *)	1845	=item w->set (struct ev_loop *)
1691		1846
1692	Associates a different C<struct ev_loop> with this watcher. You can only	1847	Associates a different C<struct ev_loop> with this watcher. You can only
1693	do this when the watcher is inactive (and not pending either).	1848	do this when the watcher is inactive (and not pending either).
1694		1849
1695	=item w->set ([args])	1850	=item w->set ([args])
1696		1851
1697	Basically the same as C<ev_TYPE_set>, with the same args. Must be	1852	Basically the same as C<ev_TYPE_set>, with the same args. Must be
1698	called at least once. Unlike the C counterpart, an active watcher gets	1853	called at least once. Unlike the C counterpart, an active watcher gets
1699	automatically stopped and restarted.	1854	automatically stopped and restarted when reconfiguring it with this
		1855	method.
1700		1856
1701	=item w->start ()	1857	=item w->start ()
1702		1858
1703	Starts the watcher. Note that there is no C<loop> argument as the	1859	Starts the watcher. Note that there is no C<loop> argument, as the
1704	constructor already takes the loop.	1860	constructor already stores the event loop.
1705		1861
1706	=item w->stop ()	1862	=item w->stop ()
1707		1863
1708	Stops the watcher if it is active. Again, no C<loop> argument.	1864	Stops the watcher if it is active. Again, no C<loop> argument.
1709		1865
…		…
1734		1890
1735	myclass ();	1891	myclass ();
1736	}	1892	}
1737		1893
1738	myclass::myclass (int fd)	1894	myclass::myclass (int fd)
1739	: io (this, &myclass::io_cb),
1740	idle (this, &myclass::idle_cb)
1741	{	1895	{
		1896	io .set <myclass, &myclass::io_cb > (this);
		1897	idle.set <myclass, &myclass::idle_cb> (this);
		1898
1742	io.start (fd, ev::READ);	1899	io.start (fd, ev::READ);
1743	}	1900	}
1744		1901
1745		1902
1746	=head1 MACRO MAGIC	1903	=head1 MACRO MAGIC
1747		1904
1748	Libev can be compiled with a variety of options, the most fundemantal is	1905	Libev can be compiled with a variety of options, the most fundemantal is
1749	C<EV_MULTIPLICITY>. This option determines wether (most) functions and	1906	C<EV_MULTIPLICITY>. This option determines whether (most) functions and
1750	callbacks have an initial C<struct ev_loop *> argument.	1907	callbacks have an initial C<struct ev_loop *> argument.
1751		1908
1752	To make it easier to write programs that cope with either variant, the	1909	To make it easier to write programs that cope with either variant, the
1753	following macros are defined:	1910	following macros are defined:
1754		1911
…		…
1787	Similar to the other two macros, this gives you the value of the default	1944	Similar to the other two macros, this gives you the value of the default
1788	loop, if multiple loops are supported ("ev loop default").	1945	loop, if multiple loops are supported ("ev loop default").
1789		1946
1790	=back	1947	=back
1791		1948
1792	Example: Declare and initialise a check watcher, working regardless of	1949	Example: Declare and initialise a check watcher, utilising the above
1793	wether multiple loops are supported or not.	1950	macros so it will work regardless of whether multiple loops are supported
		1951	or not.
1794		1952
1795	static void	1953	static void
1796	check_cb (EV_P_ ev_timer *w, int revents)	1954	check_cb (EV_P_ ev_timer *w, int revents)
1797	{	1955	{
1798	ev_check_stop (EV_A_ w);	1956	ev_check_stop (EV_A_ w);
…		…
1800		1958
1801	ev_check check;	1959	ev_check check;
1802	ev_check_init (&check, check_cb);	1960	ev_check_init (&check, check_cb);
1803	ev_check_start (EV_DEFAULT_ &check);	1961	ev_check_start (EV_DEFAULT_ &check);
1804	ev_loop (EV_DEFAULT_ 0);	1962	ev_loop (EV_DEFAULT_ 0);
1805
1806		1963
1807	=head1 EMBEDDING	1964	=head1 EMBEDDING
1808		1965
1809	Libev can (and often is) directly embedded into host	1966	Libev can (and often is) directly embedded into host
1810	applications. Examples of applications that embed it include the Deliantra	1967	applications. Examples of applications that embed it include the Deliantra
…		…
1850	ev_vars.h	2007	ev_vars.h
1851	ev_wrap.h	2008	ev_wrap.h
1852		2009
1853	ev_win32.c required on win32 platforms only	2010	ev_win32.c required on win32 platforms only
1854		2011
1855	ev_select.c only when select backend is enabled (which is by default)	2012	ev_select.c only when select backend is enabled (which is enabled by default)
1856	ev_poll.c only when poll backend is enabled (disabled by default)	2013	ev_poll.c only when poll backend is enabled (disabled by default)
1857	ev_epoll.c only when the epoll backend is enabled (disabled by default)	2014	ev_epoll.c only when the epoll backend is enabled (disabled by default)
1858	ev_kqueue.c only when the kqueue backend is enabled (disabled by default)	2015	ev_kqueue.c only when the kqueue backend is enabled (disabled by default)
1859	ev_port.c only when the solaris port backend is enabled (disabled by default)	2016	ev_port.c only when the solaris port backend is enabled (disabled by default)
1860		2017
…		…
1985		2142
1986	=item EV_USE_DEVPOLL	2143	=item EV_USE_DEVPOLL
1987		2144
1988	reserved for future expansion, works like the USE symbols above.	2145	reserved for future expansion, works like the USE symbols above.
1989		2146
		2147	=item EV_USE_INOTIFY
		2148
		2149	If defined to be C<1>, libev will compile in support for the Linux inotify
		2150	interface to speed up C<ev_stat> watchers. Its actual availability will
		2151	be detected at runtime.
		2152
1990	=item EV_H	2153	=item EV_H
1991		2154
1992	The name of the F<ev.h> header file used to include it. The default if	2155	The name of the F<ev.h> header file used to include it. The default if
1993	undefined is C<< <ev.h> >> in F<event.h> and C<"ev.h"> in F<ev.c>. This	2156	undefined is C<< <ev.h> >> in F<event.h> and C<"ev.h"> in F<ev.c>. This
1994	can be used to virtually rename the F<ev.h> header file in case of conflicts.	2157	can be used to virtually rename the F<ev.h> header file in case of conflicts.
…		…
2017	will have the C<struct ev_loop *> as first argument, and you can create	2180	will have the C<struct ev_loop *> as first argument, and you can create
2018	additional independent event loops. Otherwise there will be no support	2181	additional independent event loops. Otherwise there will be no support
2019	for multiple event loops and there is no first event loop pointer	2182	for multiple event loops and there is no first event loop pointer
2020	argument. Instead, all functions act on the single default loop.	2183	argument. Instead, all functions act on the single default loop.
2021		2184
		2185	=item EV_MINPRI
		2186
		2187	=item EV_MAXPRI
		2188
		2189	The range of allowed priorities. C<EV_MINPRI> must be smaller or equal to
		2190	C<EV_MAXPRI>, but otherwise there are no non-obvious limitations. You can
		2191	provide for more priorities by overriding those symbols (usually defined
		2192	to be C<-2> and C<2>, respectively).
		2193
		2194	When doing priority-based operations, libev usually has to linearly search
		2195	all the priorities, so having many of them (hundreds) uses a lot of space
		2196	and time, so using the defaults of five priorities (-2 .. +2) is usually
		2197	fine.
		2198
		2199	If your embedding app does not need any priorities, defining these both to
		2200	C<0> will save some memory and cpu.
		2201
2022	=item EV_PERIODIC_ENABLE	2202	=item EV_PERIODIC_ENABLE
2023		2203
2024	If undefined or defined to be C<1>, then periodic timers are supported. If	2204	If undefined or defined to be C<1>, then periodic timers are supported. If
2025	defined to be C<0>, then they are not. Disabling them saves a few kB of	2205	defined to be C<0>, then they are not. Disabling them saves a few kB of
2026	code.	2206	code.
2027		2207
		2208	=item EV_IDLE_ENABLE
		2209
		2210	If undefined or defined to be C<1>, then idle watchers are supported. If
		2211	defined to be C<0>, then they are not. Disabling them saves a few kB of
		2212	code.
		2213
2028	=item EV_EMBED_ENABLE	2214	=item EV_EMBED_ENABLE
2029		2215
2030	If undefined or defined to be C<1>, then embed watchers are supported. If	2216	If undefined or defined to be C<1>, then embed watchers are supported. If
2031	defined to be C<0>, then they are not.	2217	defined to be C<0>, then they are not.
2032		2218
…		…
2049	=item EV_PID_HASHSIZE	2235	=item EV_PID_HASHSIZE
2050		2236
2051	C<ev_child> watchers use a small hash table to distribute workload by	2237	C<ev_child> watchers use a small hash table to distribute workload by
2052	pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more	2238	pid. The default size is C<16> (or C<1> with C<EV_MINIMAL>), usually more
2053	than enough. If you need to manage thousands of children you might want to	2239	than enough. If you need to manage thousands of children you might want to
2054	increase this value.	2240	increase this value (I<must> be a power of two).
		2241
		2242	=item EV_INOTIFY_HASHSIZE
		2243
		2244	C<ev_staz> watchers use a small hash table to distribute workload by
		2245	inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>),
		2246	usually more than enough. If you need to manage thousands of C<ev_stat>
		2247	watchers you might want to increase this value (I<must> be a power of
		2248	two).
2055		2249
2056	=item EV_COMMON	2250	=item EV_COMMON
2057		2251
2058	By default, all watchers have a C<void *data> member. By redefining	2252	By default, all watchers have a C<void *data> member. By redefining
2059	this macro to a something else you can include more and other types of	2253	this macro to a something else you can include more and other types of
…		…
2088	interface) and F<EV.xs> (implementation) files. Only the F<EV.xs> file	2282	interface) and F<EV.xs> (implementation) files. Only the F<EV.xs> file
2089	will be compiled. It is pretty complex because it provides its own header	2283	will be compiled. It is pretty complex because it provides its own header
2090	file.	2284	file.
2091		2285
2092	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file	2286	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file
2093	that everybody includes and which overrides some autoconf choices:	2287	that everybody includes and which overrides some configure choices:
2094		2288
		2289	#define EV_MINIMAL 1
2095	#define EV_USE_POLL 0	2290	#define EV_USE_POLL 0
2096	#define EV_MULTIPLICITY 0	2291	#define EV_MULTIPLICITY 0
2097	#define EV_PERIODICS 0	2292	#define EV_PERIODIC_ENABLE 0
		2293	#define EV_STAT_ENABLE 0
		2294	#define EV_FORK_ENABLE 0
2098	#define EV_CONFIG_H <config.h>	2295	#define EV_CONFIG_H <config.h>
		2296	#define EV_MINPRI 0
		2297	#define EV_MAXPRI 0
2099		2298
2100	#include "ev++.h"	2299	#include "ev++.h"
2101		2300
2102	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:	2301	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:
2103		2302
…		…
2109		2308
2110	In this section the complexities of (many of) the algorithms used inside	2309	In this section the complexities of (many of) the algorithms used inside
2111	libev will be explained. For complexity discussions about backends see the	2310	libev will be explained. For complexity discussions about backends see the
2112	documentation for C<ev_default_init>.	2311	documentation for C<ev_default_init>.
2113		2312
		2313	All of the following are about amortised time: If an array needs to be
		2314	extended, libev needs to realloc and move the whole array, but this
		2315	happens asymptotically never with higher number of elements, so O(1) might
		2316	mean it might do a lengthy realloc operation in rare cases, but on average
		2317	it is much faster and asymptotically approaches constant time.
		2318
2114	=over 4	2319	=over 4
2115		2320
2116	=item Starting and stopping timer/periodic watchers: O(log skipped_other_timers)	2321	=item Starting and stopping timer/periodic watchers: O(log skipped_other_timers)
2117		2322
		2323	This means that, when you have a watcher that triggers in one hour and
		2324	there are 100 watchers that would trigger before that then inserting will
		2325	have to skip those 100 watchers.
		2326
2118	=item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)	2327	=item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)
2119		2328
		2329	That means that for changing a timer costs less than removing/adding them
		2330	as only the relative motion in the event queue has to be paid for.
		2331
2120	=item Starting io/check/prepare/idle/signal/child watchers: O(1)	2332	=item Starting io/check/prepare/idle/signal/child watchers: O(1)
2121		2333
		2334	These just add the watcher into an array or at the head of a list.
2122	=item Stopping check/prepare/idle watchers: O(1)	2335	=item Stopping check/prepare/idle watchers: O(1)
2123		2336
2124	=item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % 16))	2337	=item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))
		2338
		2339	These watchers are stored in lists then need to be walked to find the
		2340	correct watcher to remove. The lists are usually short (you don't usually
		2341	have many watchers waiting for the same fd or signal).
2125		2342
2126	=item Finding the next timer per loop iteration: O(1)	2343	=item Finding the next timer per loop iteration: O(1)
2127		2344
2128	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)	2345	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)
2129		2346
		2347	A change means an I/O watcher gets started or stopped, which requires
		2348	libev to recalculate its status (and possibly tell the kernel).
		2349
2130	=item Activating one watcher: O(1)	2350	=item Activating one watcher: O(1)
2131		2351
		2352	=item Priority handling: O(number_of_priorities)
		2353
		2354	Priorities are implemented by allocating some space for each
		2355	priority. When doing priority-based operations, libev usually has to
		2356	linearly search all the priorities.
		2357
2132	=back	2358	=back
2133		2359
2134		2360
2135	=head1 AUTHOR	2361	=head1 AUTHOR
2136		2362

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Comparing libev/ev.pod (file contents): Revision 1.54 by root, Tue Nov 27 20:26:51 2007 UTC vs. Revision 1.73 by root, Sat Dec 8 03:53:36 2007 UTC

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Comparing libev/ev.pod (file contents):
Revision 1.54 by root, Tue Nov 27 20:26:51 2007 UTC vs.
Revision 1.73 by root, Sat Dec 8 03:53:36 2007 UTC