[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 1.69 by root, Fri Dec 7 19:15:39 2007 UTC

…		…
48	return 0;	48	return 0;
49	}	49	}
50		50
51	=head1 DESCRIPTION	51	=head1 DESCRIPTION
52		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>.
		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
57	To do this, it must take more or less complete control over your process	61	To do this, it must take more or less complete control over your process
…		…
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.
…		…
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) and you must make sure the watcher is available to
706	libev (e.g. you cnanot C<free ()> it).	742	libev (e.g. you cnanot C<free ()> it).
707		743
708	=item callback = ev_cb (ev_TYPE *watcher)	744	=item callback ev_cb (ev_TYPE *watcher)
709		745
710	Returns the callback currently set on the watcher.	746	Returns the callback currently set on the watcher.
711		747
712	=item ev_cb_set (ev_TYPE *watcher, callback)	748	=item ev_cb_set (ev_TYPE *watcher, callback)
713		749
714	Change the callback. You can change the callback at virtually any time	750	Change the callback. You can change the callback at virtually any time
715	(modulo threads).	751	(modulo threads).
		752
		753	=item ev_set_priority (ev_TYPE *watcher, priority)
		754
		755	=item int ev_priority (ev_TYPE *watcher)
		756
		757	Set and query the priority of the watcher. The priority is a small
		758	integer between C<EV_MAXPRI> (default: C<2>) and C<EV_MINPRI>
		759	(default: C<-2>). Pending watchers with higher priority will be invoked
		760	before watchers with lower priority, but priority will not keep watchers
		761	from being executed (except for C<ev_idle> watchers).
		762
		763	This means that priorities are I<only> used for ordering callback
		764	invocation after new events have been received. This is useful, for
		765	example, to reduce latency after idling, or more often, to bind two
		766	watchers on the same event and make sure one is called first.
		767
		768	If you need to suppress invocation when higher priority events are pending
		769	you need to look at C<ev_idle> watchers, which provide this functionality.
		770
		771	The default priority used by watchers when no priority has been set is
		772	always C<0>, which is supposed to not be too high and not be too low :).
		773
		774	Setting a priority outside the range of C<EV_MINPRI> to C<EV_MAXPRI> is
		775	fine, as long as you do not mind that the priority value you query might
		776	or might not have been adjusted to be within valid range.
716		777
717	=back	778	=back
718		779
719		780
720	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER	781	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER
…		…
741	{	802	{
742	struct my_io w = (struct my_io )w_;	803	struct my_io w = (struct my_io )w_;
743	...	804	...
744	}	805	}
745		806
746	More interesting and less C-conformant ways of catsing your callback type	807	More interesting and less C-conformant ways of casting your callback type
747	have been omitted....	808	instead have been omitted.
		809
		810	Another common scenario is having some data structure with multiple
		811	watchers:
		812
		813	struct my_biggy
		814	{
		815	int some_data;
		816	ev_timer t1;
		817	ev_timer t2;
		818	}
		819
		820	In this case getting the pointer to C<my_biggy> is a bit more complicated,
		821	you need to use C<offsetof>:
		822
		823	#include <stddef.h>
		824
		825	static void
		826	t1_cb (EV_P_ struct ev_timer *w, int revents)
		827	{
		828	struct my_biggy big = (struct my_biggy *
		829	(((char *)w) - offsetof (struct my_biggy, t1));
		830	}
		831
		832	static void
		833	t2_cb (EV_P_ struct ev_timer *w, int revents)
		834	{
		835	struct my_biggy big = (struct my_biggy *
		836	(((char *)w) - offsetof (struct my_biggy, t2));
		837	}
748		838
749		839
750	=head1 WATCHER TYPES	840	=head1 WATCHER TYPES
751		841
752	This section describes each watcher in detail, but will not repeat	842	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	887	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.	888	C<EAGAIN> is far preferable to a program hanging until some data arrives.
799		889
800	If you cannot run the fd in non-blocking mode (for example you should not	890	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	891	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	892	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	893	such as poll (fortunately in our Xlib example, Xlib already does this on
804	its own, so its quite safe to use).	894	its own, so its quite safe to use).
805		895
806	=over 4	896	=over 4
807		897
…		…
885	=item ev_timer_again (loop)	975	=item ev_timer_again (loop)
886		976
887	This will act as if the timer timed out and restart it again if it is	977	This will act as if the timer timed out and restart it again if it is
888	repeating. The exact semantics are:	978	repeating. The exact semantics are:
889		979
		980	If the timer is pending, its pending status is cleared.
		981
890	If the timer is started but nonrepeating, stop it.	982	If the timer is started but nonrepeating, stop it (as if it timed out).
891		983
892	If the timer is repeating, either start it if necessary (with the repeat	984	If the timer is repeating, either start it if necessary (with the
893	value), or reset the running timer to the repeat value.	985	C<repeat> value), or reset the running timer to the C<repeat> value.
894		986
895	This sounds a bit complicated, but here is a useful and typical	987	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	988	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,	989	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	990	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	991	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	992	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	993	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	994	socket, you can C<ev_timer_stop> the timer, and C<ev_timer_again> will
903	need be.	995	automatically restart it if need be.
904		996
905	You can also ignore the C<after> value and C<ev_timer_start> altogether	997	That means you can ignore the C<after> value and C<ev_timer_start>
906	and only ever use the C<repeat> value:	998	altogether and only ever use the C<repeat> value and C<ev_timer_again>:
907		999
908	ev_timer_init (timer, callback, 0., 5.);	1000	ev_timer_init (timer, callback, 0., 5.);
909	ev_timer_again (loop, timer);	1001	ev_timer_again (loop, timer);
910	...	1002	...
911	timer->again = 17.;	1003	timer->again = 17.;
912	ev_timer_again (loop, timer);	1004	ev_timer_again (loop, timer);
913	...	1005	...
914	timer->again = 10.;	1006	timer->again = 10.;
915	ev_timer_again (loop, timer);	1007	ev_timer_again (loop, timer);
916		1008
917	This is more efficient then stopping/starting the timer eahc time you want	1009	This is more slightly efficient then stopping/starting the timer each time
918	to modify its timeout value.	1010	you want to modify its timeout value.
919		1011
920	=item ev_tstamp repeat [read-write]	1012	=item ev_tstamp repeat [read-write]
921		1013
922	The current C<repeat> value. Will be used each time the watcher times out	1014	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),	1015	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	1284	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	1285	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	1286	otherwise always forced to be at least one) and all the other fields of
1195	the stat buffer having unspecified contents.	1287	the stat buffer having unspecified contents.
1196		1288
		1289	The path I<should> be absolute and I<must not> end in a slash. If it is
		1290	relative and your working directory changes, the behaviour is undefined.
		1291
1197	Since there is no standard to do this, the portable implementation simply	1292	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	1293	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	1294	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,	1295	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	1296	unspecified default> value will be used (which you can expect to be around
1202	five seconds, although this might change dynamically). Libev will also	1297	five seconds, although this might change dynamically). Libev will also
1203	impose a minimum interval which is currently around C<0.1>, but thats	1298	impose a minimum interval which is currently around C<0.1>, but thats
…		…
1205		1300
1206	This watcher type is not meant for massive numbers of stat watchers,	1301	This watcher type is not meant for massive numbers of stat watchers,
1207	as even with OS-supported change notifications, this can be	1302	as even with OS-supported change notifications, this can be
1208	resource-intensive.	1303	resource-intensive.
1209		1304
1210	At the time of this writing, no specific OS backends are implemented, but	1305	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.	1306	implemented (implementing kqueue support is left as an exercise for the
		1307	reader). Inotify will be used to give hints only and should not change the
		1308	semantics of C<ev_stat> watchers, which means that libev sometimes needs
		1309	to fall back to regular polling again even with inotify, but changes are
		1310	usually detected immediately, and if the file exists there will be no
		1311	polling.
1212		1312
1213	=over 4	1313	=over 4
1214		1314
1215	=item ev_stat_init (ev_stat , callback, const char path, ev_tstamp interval)	1315	=item ev_stat_init (ev_stat , callback, const char path, ev_tstamp interval)
1216		1316
…		…
1280	ev_stat_start (loop, &passwd);	1380	ev_stat_start (loop, &passwd);
1281		1381
1282		1382
1283	=head2 C<ev_idle> - when you've got nothing better to do...	1383	=head2 C<ev_idle> - when you've got nothing better to do...
1284		1384
1285	Idle watchers trigger events when there are no other events are pending	1385	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	1386	priority are pending (prepare, check and other idle watchers do not
1287	as your process is busy handling sockets or timeouts (or even signals,	1387	count).
1288	imagine) it will not be triggered. But when your process is idle all idle	1388
1289	watchers are being called again and again, once per event loop iteration -	1389	That is, as long as your process is busy handling sockets or timeouts
		1390	(or even signals, imagine) of the same or higher priority it will not be
		1391	triggered. But when your process is idle (or only lower-priority watchers
		1392	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	1393	iteration - until stopped, that is, or your process receives more events
1291	busy.	1394	and becomes busy again with higher priority stuff.
1292		1395
1293	The most noteworthy effect is that as long as any idle watchers are	1396	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.	1397	active, the process will not block when waiting for new events.
1295		1398
1296	Apart from keeping your process non-blocking (which is a useful	1399	Apart from keeping your process non-blocking (which is a useful
…		…
1396		1499
1397	// create io watchers for each fd and a timer before blocking	1500	// create io watchers for each fd and a timer before blocking
1398	static void	1501	static void
1399	adns_prepare_cb (ev_loop loop, ev_prepare w, int revents)	1502	adns_prepare_cb (ev_loop loop, ev_prepare w, int revents)
1400	{	1503	{
1401	int timeout = 3600000;truct pollfd fds [nfd];	1504	int timeout = 3600000;
		1505	struct pollfd fds [nfd];
1402	// actual code will need to loop here and realloc etc.	1506	// actual code will need to loop here and realloc etc.
1403	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));	1507	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));
1404		1508
1405	/* the callback is illegal, but won't be called as we stop during check */	1509	/* the callback is illegal, but won't be called as we stop during check */
1406	ev_timer_init (&tw, 0, timeout * 1e-3);	1510	ev_timer_init (&tw, 0, timeout * 1e-3);
…		…
1744		1848
1745		1849
1746	=head1 MACRO MAGIC	1850	=head1 MACRO MAGIC
1747		1851
1748	Libev can be compiled with a variety of options, the most fundemantal is	1852	Libev can be compiled with a variety of options, the most fundemantal is
1749	C<EV_MULTIPLICITY>. This option determines wether (most) functions and	1853	C<EV_MULTIPLICITY>. This option determines whether (most) functions and
1750	callbacks have an initial C<struct ev_loop *> argument.	1854	callbacks have an initial C<struct ev_loop *> argument.
1751		1855
1752	To make it easier to write programs that cope with either variant, the	1856	To make it easier to write programs that cope with either variant, the
1753	following macros are defined:	1857	following macros are defined:
1754		1858
…		…
1787	Similar to the other two macros, this gives you the value of the default	1891	Similar to the other two macros, this gives you the value of the default
1788	loop, if multiple loops are supported ("ev loop default").	1892	loop, if multiple loops are supported ("ev loop default").
1789		1893
1790	=back	1894	=back
1791		1895
1792	Example: Declare and initialise a check watcher, working regardless of	1896	Example: Declare and initialise a check watcher, utilising the above
1793	wether multiple loops are supported or not.	1897	macros so it will work regardless of whether multiple loops are supported
		1898	or not.
1794		1899
1795	static void	1900	static void
1796	check_cb (EV_P_ ev_timer *w, int revents)	1901	check_cb (EV_P_ ev_timer *w, int revents)
1797	{	1902	{
1798	ev_check_stop (EV_A_ w);	1903	ev_check_stop (EV_A_ w);
…		…
1801	ev_check check;	1906	ev_check check;
1802	ev_check_init (&check, check_cb);	1907	ev_check_init (&check, check_cb);
1803	ev_check_start (EV_DEFAULT_ &check);	1908	ev_check_start (EV_DEFAULT_ &check);
1804	ev_loop (EV_DEFAULT_ 0);	1909	ev_loop (EV_DEFAULT_ 0);
1805		1910
1806
1807	=head1 EMBEDDING	1911	=head1 EMBEDDING
1808		1912
1809	Libev can (and often is) directly embedded into host	1913	Libev can (and often is) directly embedded into host
1810	applications. Examples of applications that embed it include the Deliantra	1914	applications. Examples of applications that embed it include the Deliantra
1811	Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe)	1915	Game Server, the EV perl module, the GNU Virtual Private Ethernet (gvpe)
…		…
1850	ev_vars.h	1954	ev_vars.h
1851	ev_wrap.h	1955	ev_wrap.h
1852		1956
1853	ev_win32.c required on win32 platforms only	1957	ev_win32.c required on win32 platforms only
1854		1958
1855	ev_select.c only when select backend is enabled (which is by default)	1959	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)	1960	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)	1961	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)	1962	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)	1963	ev_port.c only when the solaris port backend is enabled (disabled by default)
1860		1964
…		…
1985		2089
1986	=item EV_USE_DEVPOLL	2090	=item EV_USE_DEVPOLL
1987		2091
1988	reserved for future expansion, works like the USE symbols above.	2092	reserved for future expansion, works like the USE symbols above.
1989		2093
		2094	=item EV_USE_INOTIFY
		2095
		2096	If defined to be C<1>, libev will compile in support for the Linux inotify
		2097	interface to speed up C<ev_stat> watchers. Its actual availability will
		2098	be detected at runtime.
		2099
1990	=item EV_H	2100	=item EV_H
1991		2101
1992	The name of the F<ev.h> header file used to include it. The default if	2102	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	2103	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.	2104	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	2127	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	2128	additional independent event loops. Otherwise there will be no support
2019	for multiple event loops and there is no first event loop pointer	2129	for multiple event loops and there is no first event loop pointer
2020	argument. Instead, all functions act on the single default loop.	2130	argument. Instead, all functions act on the single default loop.
2021		2131
		2132	=item EV_MINPRI
		2133
		2134	=item EV_MAXPRI
		2135
		2136	The range of allowed priorities. C<EV_MINPRI> must be smaller or equal to
		2137	C<EV_MAXPRI>, but otherwise there are no non-obvious limitations. You can
		2138	provide for more priorities by overriding those symbols (usually defined
		2139	to be C<-2> and C<2>, respectively).
		2140
		2141	When doing priority-based operations, libev usually has to linearly search
		2142	all the priorities, so having many of them (hundreds) uses a lot of space
		2143	and time, so using the defaults of five priorities (-2 .. +2) is usually
		2144	fine.
		2145
		2146	If your embedding app does not need any priorities, defining these both to
		2147	C<0> will save some memory and cpu.
		2148
2022	=item EV_PERIODIC_ENABLE	2149	=item EV_PERIODIC_ENABLE
2023		2150
2024	If undefined or defined to be C<1>, then periodic timers are supported. If	2151	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	2152	defined to be C<0>, then they are not. Disabling them saves a few kB of
2026	code.	2153	code.
2027		2154
		2155	=item EV_IDLE_ENABLE
		2156
		2157	If undefined or defined to be C<1>, then idle watchers are supported. If
		2158	defined to be C<0>, then they are not. Disabling them saves a few kB of
		2159	code.
		2160
2028	=item EV_EMBED_ENABLE	2161	=item EV_EMBED_ENABLE
2029		2162
2030	If undefined or defined to be C<1>, then embed watchers are supported. If	2163	If undefined or defined to be C<1>, then embed watchers are supported. If
2031	defined to be C<0>, then they are not.	2164	defined to be C<0>, then they are not.
2032		2165
…		…
2049	=item EV_PID_HASHSIZE	2182	=item EV_PID_HASHSIZE
2050		2183
2051	C<ev_child> watchers use a small hash table to distribute workload by	2184	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	2185	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	2186	than enough. If you need to manage thousands of children you might want to
2054	increase this value.	2187	increase this value (I<must> be a power of two).
		2188
		2189	=item EV_INOTIFY_HASHSIZE
		2190
		2191	C<ev_staz> watchers use a small hash table to distribute workload by
		2192	inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>),
		2193	usually more than enough. If you need to manage thousands of C<ev_stat>
		2194	watchers you might want to increase this value (I<must> be a power of
		2195	two).
2055		2196
2056	=item EV_COMMON	2197	=item EV_COMMON
2057		2198
2058	By default, all watchers have a C<void *data> member. By redefining	2199	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	2200	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	2229	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	2230	will be compiled. It is pretty complex because it provides its own header
2090	file.	2231	file.
2091		2232
2092	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file	2233	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:	2234	that everybody includes and which overrides some configure choices:
2094		2235
		2236	#define EV_MINIMAL 1
2095	#define EV_USE_POLL 0	2237	#define EV_USE_POLL 0
2096	#define EV_MULTIPLICITY 0	2238	#define EV_MULTIPLICITY 0
2097	#define EV_PERIODICS 0	2239	#define EV_PERIODIC_ENABLE 0
		2240	#define EV_STAT_ENABLE 0
		2241	#define EV_FORK_ENABLE 0
2098	#define EV_CONFIG_H <config.h>	2242	#define EV_CONFIG_H <config.h>
		2243	#define EV_MINPRI 0
		2244	#define EV_MAXPRI 0
2099		2245
2100	#include "ev++.h"	2246	#include "ev++.h"
2101		2247
2102	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:	2248	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:
2103		2249
…		…
2113		2259
2114	=over 4	2260	=over 4
2115		2261
2116	=item Starting and stopping timer/periodic watchers: O(log skipped_other_timers)	2262	=item Starting and stopping timer/periodic watchers: O(log skipped_other_timers)
2117		2263
		2264	This means that, when you have a watcher that triggers in one hour and
		2265	there are 100 watchers that would trigger before that then inserting will
		2266	have to skip those 100 watchers.
		2267
2118	=item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)	2268	=item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)
2119		2269
		2270	That means that for changing a timer costs less than removing/adding them
		2271	as only the relative motion in the event queue has to be paid for.
		2272
2120	=item Starting io/check/prepare/idle/signal/child watchers: O(1)	2273	=item Starting io/check/prepare/idle/signal/child watchers: O(1)
2121		2274
		2275	These just add the watcher into an array or at the head of a list. If
		2276	the array needs to be extended libev needs to realloc and move the whole
		2277	array, but this happen asymptotically less and less with more watchers,
		2278	thus amortised O(1).
		2279
2122	=item Stopping check/prepare/idle watchers: O(1)	2280	=item Stopping check/prepare/idle watchers: O(1)
2123		2281
2124	=item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % 16))	2282	=item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))
		2283
		2284	These watchers are stored in lists then need to be walked to find the
		2285	correct watcher to remove. The lists are usually short (you don't usually
		2286	have many watchers waiting for the same fd or signal).
2125		2287
2126	=item Finding the next timer per loop iteration: O(1)	2288	=item Finding the next timer per loop iteration: O(1)
2127		2289
2128	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)	2290	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)
2129		2291
		2292	A change means an I/O watcher gets started or stopped, which requires
		2293	libev to recalculate its status (and possibly tell the kernel).
		2294
2130	=item Activating one watcher: O(1)	2295	=item Activating one watcher: O(1)
2131		2296
		2297	=item Priority handling: O(number_of_priorities)
		2298
		2299	Priorities are implemented by allocating some space for each
		2300	priority. When doing priority-based operations, libev usually has to
		2301	linearly search all the priorities.
		2302
2132	=back	2303	=back
2133		2304
2134		2305
2135	=head1 AUTHOR	2306	=head1 AUTHOR
2136		2307

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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 1.69 by root, Fri Dec 7 19:15:39 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 1.69 by root, Fri Dec 7 19:15:39 2007 UTC