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

Comparing libev/ev.pod (file contents):
Revision 1.55 by root, Tue Nov 27 20:38:07 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.
…		…
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).
716		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.
		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
721		782
…		…
826	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
827	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.
828		889
829	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
830	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
831	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
832	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
833	its own, so its quite safe to use).	894	its own, so its quite safe to use).
834		895
835	=over 4	896	=over 4
836		897
…		…
914	=item ev_timer_again (loop)	975	=item ev_timer_again (loop)
915		976
916	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
917	repeating. The exact semantics are:	978	repeating. The exact semantics are:
918		979
		980	If the timer is pending, its pending status is cleared.
		981
919	If the timer is started but nonrepeating, stop it.	982	If the timer is started but nonrepeating, stop it (as if it timed out).
920		983
921	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
922	value), or reset the running timer to the repeat value.	985	C<repeat> value), or reset the running timer to the C<repeat> value.
923		986
924	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
925	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
926	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
927	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
928	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
929	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
930	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
931	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
932	need be.	995	automatically restart it if need be.
933		996
934	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>
935	and only ever use the C<repeat> value:	998	altogether and only ever use the C<repeat> value and C<ev_timer_again>:
936		999
937	ev_timer_init (timer, callback, 0., 5.);	1000	ev_timer_init (timer, callback, 0., 5.);
938	ev_timer_again (loop, timer);	1001	ev_timer_again (loop, timer);
939	...	1002	...
940	timer->again = 17.;	1003	timer->again = 17.;
941	ev_timer_again (loop, timer);	1004	ev_timer_again (loop, timer);
942	...	1005	...
943	timer->again = 10.;	1006	timer->again = 10.;
944	ev_timer_again (loop, timer);	1007	ev_timer_again (loop, timer);
945		1008
946	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
947	to modify its timeout value.	1010	you want to modify its timeout value.
948		1011
949	=item ev_tstamp repeat [read-write]	1012	=item ev_tstamp repeat [read-write]
950		1013
951	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
952	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),
…		…
1221	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
1222	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
1223	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
1224	the stat buffer having unspecified contents.	1287	the stat buffer having unspecified contents.
1225		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
1226	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
1227	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
1228	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
1229	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,
1230	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
1231	five seconds, although this might change dynamically). Libev will also	1297	five seconds, although this might change dynamically). Libev will also
1232	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
…		…
1234		1300
1235	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,
1236	as even with OS-supported change notifications, this can be	1302	as even with OS-supported change notifications, this can be
1237	resource-intensive.	1303	resource-intensive.
1238		1304
1239	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
1240	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.
1241		1312
1242	=over 4	1313	=over 4
1243		1314
1244	=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)
1245		1316
…		…
1309	ev_stat_start (loop, &passwd);	1380	ev_stat_start (loop, &passwd);
1310		1381
1311		1382
1312	=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...
1313		1384
1314	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
1315	(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
1316	as your process is busy handling sockets or timeouts (or even signals,	1387	count).
1317	imagine) it will not be triggered. But when your process is idle all idle	1388
1318	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
1319	until stopped, that is, or your process receives more events and becomes	1393	iteration - until stopped, that is, or your process receives more events
1320	busy.	1394	and becomes busy again with higher priority stuff.
1321		1395
1322	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
1323	active, the process will not block when waiting for new events.	1397	active, the process will not block when waiting for new events.
1324		1398
1325	Apart from keeping your process non-blocking (which is a useful	1399	Apart from keeping your process non-blocking (which is a useful
…		…
1425		1499
1426	// create io watchers for each fd and a timer before blocking	1500	// create io watchers for each fd and a timer before blocking
1427	static void	1501	static void
1428	adns_prepare_cb (ev_loop loop, ev_prepare w, int revents)	1502	adns_prepare_cb (ev_loop loop, ev_prepare w, int revents)
1429	{	1503	{
1430	int timeout = 3600000;truct pollfd fds [nfd];	1504	int timeout = 3600000;
		1505	struct pollfd fds [nfd];
1431	// actual code will need to loop here and realloc etc.	1506	// actual code will need to loop here and realloc etc.
1432	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));	1507	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));
1433		1508
1434	/* 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 */
1435	ev_timer_init (&tw, 0, timeout * 1e-3);	1510	ev_timer_init (&tw, 0, timeout * 1e-3);
…		…
1773		1848
1774		1849
1775	=head1 MACRO MAGIC	1850	=head1 MACRO MAGIC
1776		1851
1777	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
1778	C<EV_MULTIPLICITY>. This option determines wether (most) functions and	1853	C<EV_MULTIPLICITY>. This option determines whether (most) functions and
1779	callbacks have an initial C<struct ev_loop *> argument.	1854	callbacks have an initial C<struct ev_loop *> argument.
1780		1855
1781	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
1782	following macros are defined:	1857	following macros are defined:
1783		1858
…		…
1816	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
1817	loop, if multiple loops are supported ("ev loop default").	1892	loop, if multiple loops are supported ("ev loop default").
1818		1893
1819	=back	1894	=back
1820		1895
1821	Example: Declare and initialise a check watcher, working regardless of	1896	Example: Declare and initialise a check watcher, utilising the above
1822	wether multiple loops are supported or not.	1897	macros so it will work regardless of whether multiple loops are supported
		1898	or not.
1823		1899
1824	static void	1900	static void
1825	check_cb (EV_P_ ev_timer *w, int revents)	1901	check_cb (EV_P_ ev_timer *w, int revents)
1826	{	1902	{
1827	ev_check_stop (EV_A_ w);	1903	ev_check_stop (EV_A_ w);
…		…
1830	ev_check check;	1906	ev_check check;
1831	ev_check_init (&check, check_cb);	1907	ev_check_init (&check, check_cb);
1832	ev_check_start (EV_DEFAULT_ &check);	1908	ev_check_start (EV_DEFAULT_ &check);
1833	ev_loop (EV_DEFAULT_ 0);	1909	ev_loop (EV_DEFAULT_ 0);
1834		1910
1835
1836	=head1 EMBEDDING	1911	=head1 EMBEDDING
1837		1912
1838	Libev can (and often is) directly embedded into host	1913	Libev can (and often is) directly embedded into host
1839	applications. Examples of applications that embed it include the Deliantra	1914	applications. Examples of applications that embed it include the Deliantra
1840	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)
…		…
1879	ev_vars.h	1954	ev_vars.h
1880	ev_wrap.h	1955	ev_wrap.h
1881		1956
1882	ev_win32.c required on win32 platforms only	1957	ev_win32.c required on win32 platforms only
1883		1958
1884	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)
1885	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)
1886	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)
1887	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)
1888	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)
1889		1964
…		…
2014		2089
2015	=item EV_USE_DEVPOLL	2090	=item EV_USE_DEVPOLL
2016		2091
2017	reserved for future expansion, works like the USE symbols above.	2092	reserved for future expansion, works like the USE symbols above.
2018		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
2019	=item EV_H	2100	=item EV_H
2020		2101
2021	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
2022	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
2023	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.
…		…
2046	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
2047	additional independent event loops. Otherwise there will be no support	2128	additional independent event loops. Otherwise there will be no support
2048	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
2049	argument. Instead, all functions act on the single default loop.	2130	argument. Instead, all functions act on the single default loop.
2050		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
2051	=item EV_PERIODIC_ENABLE	2149	=item EV_PERIODIC_ENABLE
2052		2150
2053	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
2054	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
2055	code.	2153	code.
2056		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
2057	=item EV_EMBED_ENABLE	2161	=item EV_EMBED_ENABLE
2058		2162
2059	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
2060	defined to be C<0>, then they are not.	2164	defined to be C<0>, then they are not.
2061		2165
…		…
2078	=item EV_PID_HASHSIZE	2182	=item EV_PID_HASHSIZE
2079		2183
2080	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
2081	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
2082	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
2083	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).
2084		2196
2085	=item EV_COMMON	2197	=item EV_COMMON
2086		2198
2087	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
2088	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
…		…
2117	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
2118	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
2119	file.	2231	file.
2120		2232
2121	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
2122	that everybody includes and which overrides some autoconf choices:	2234	that everybody includes and which overrides some configure choices:
2123		2235
		2236	#define EV_MINIMAL 1
2124	#define EV_USE_POLL 0	2237	#define EV_USE_POLL 0
2125	#define EV_MULTIPLICITY 0	2238	#define EV_MULTIPLICITY 0
2126	#define EV_PERIODICS 0	2239	#define EV_PERIODIC_ENABLE 0
		2240	#define EV_STAT_ENABLE 0
		2241	#define EV_FORK_ENABLE 0
2127	#define EV_CONFIG_H <config.h>	2242	#define EV_CONFIG_H <config.h>
		2243	#define EV_MINPRI 0
		2244	#define EV_MAXPRI 0
2128		2245
2129	#include "ev++.h"	2246	#include "ev++.h"
2130		2247
2131	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:
2132		2249
…		…
2142		2259
2143	=over 4	2260	=over 4
2144		2261
2145	=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)
2146		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
2147	=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)
2148		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
2149	=item Starting io/check/prepare/idle/signal/child watchers: O(1)	2273	=item Starting io/check/prepare/idle/signal/child watchers: O(1)
2150		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
2151	=item Stopping check/prepare/idle watchers: O(1)	2280	=item Stopping check/prepare/idle watchers: O(1)
2152		2281
2153	=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).
2154		2287
2155	=item Finding the next timer per loop iteration: O(1)	2288	=item Finding the next timer per loop iteration: O(1)
2156		2289
2157	=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)
2158		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
2159	=item Activating one watcher: O(1)	2295	=item Activating one watcher: O(1)
2160		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
2161	=back	2303	=back
2162		2304
2163		2305
2164	=head1 AUTHOR	2306	=head1 AUTHOR
2165		2307

Diff Legend

-–
+Removed lines
-+
+Added lines
-<
+Changed lines
->
+Changed lines

Comparing libev/ev.pod (file contents): Revision 1.55 by root, Tue Nov 27 20:38:07 2007 UTC vs. Revision 1.69 by root, Fri Dec 7 19:15:39 2007 UTC

Diff Legend

Comparing libev/ev.pod (file contents):
Revision 1.55 by root, Tue Nov 27 20:38:07 2007 UTC vs.
Revision 1.69 by root, Fri Dec 7 19:15:39 2007 UTC