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

Comparing libev/ev.pod (file contents):
Revision 1.59 by root, Wed Nov 28 17:32:24 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
…		…
266	C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will	270	C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will
267	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
268	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
269	around bugs.	273	around bugs.
270		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
271	=item C<EVBACKEND_SELECT> (value 1, portable select backend)	295	=item C<EVBACKEND_SELECT> (value 1, portable select backend)
272		296
273	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
274	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,
275	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
…		…
409	=item ev_loop_fork (loop)	433	=item ev_loop_fork (loop)
410		434
411	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
412	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
413	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.
414		448
415	=item unsigned int ev_backend (loop)	449	=item unsigned int ev_backend (loop)
416		450
417	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
418	use.	452	use.
…		…
702	=item bool ev_is_pending (ev_TYPE *watcher)	736	=item bool ev_is_pending (ev_TYPE *watcher)
703		737
704	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
705	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
706	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
707	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
708	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).
709		744
710	=item callback ev_cb (ev_TYPE *watcher)	745	=item callback ev_cb (ev_TYPE *watcher)
711		746
712	Returns the callback currently set on the watcher.	747	Returns the callback currently set on the watcher.
713		748
714	=item ev_cb_set (ev_TYPE *watcher, callback)	749	=item ev_cb_set (ev_TYPE *watcher, callback)
715		750
716	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
717	(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.
718		781
719	=back	782	=back
720		783
721		784
722	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER	785	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER
…		…
828	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
829	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.
830		893
831	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
832	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
833	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
834	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
835	its own, so its quite safe to use).	898	its own, so its quite safe to use).
836		899
837	=over 4	900	=over 4
838		901
…		…
916	=item ev_timer_again (loop)	979	=item ev_timer_again (loop)
917		980
918	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
919	repeating. The exact semantics are:	982	repeating. The exact semantics are:
920		983
		984	If the timer is pending, its pending status is cleared.
		985
921	If the timer is started but nonrepeating, stop it.	986	If the timer is started but nonrepeating, stop it (as if it timed out).
922		987
923	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
924	value), or reset the running timer to the repeat value.	989	C<repeat> value), or reset the running timer to the C<repeat> value.
925		990
926	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
927	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
928	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
929	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
930	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
931	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
932	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
933	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
934	need be.	999	automatically restart it if need be.
935		1000
936	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>
937	and only ever use the C<repeat> value:	1002	altogether and only ever use the C<repeat> value and C<ev_timer_again>:
938		1003
939	ev_timer_init (timer, callback, 0., 5.);	1004	ev_timer_init (timer, callback, 0., 5.);
940	ev_timer_again (loop, timer);	1005	ev_timer_again (loop, timer);
941	...	1006	...
942	timer->again = 17.;	1007	timer->again = 17.;
943	ev_timer_again (loop, timer);	1008	ev_timer_again (loop, timer);
944	...	1009	...
945	timer->again = 10.;	1010	timer->again = 10.;
946	ev_timer_again (loop, timer);	1011	ev_timer_again (loop, timer);
947		1012
948	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
949	to modify its timeout value.	1014	you want to modify its timeout value.
950		1015
951	=item ev_tstamp repeat [read-write]	1016	=item ev_tstamp repeat [read-write]
952		1017
953	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
954	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),
…		…
1222	The path does not need to exist: changing from "path exists" to "path does	1287	The path does not need to exist: changing from "path exists" to "path does
1223	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
1224	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
1225	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
1226	the stat buffer having unspecified contents.	1291	the stat buffer having unspecified contents.
		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.
1227		1295
1228	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
1229	calls C<stat (2)> regularly 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
1230	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
1231	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,
…		…
1316	ev_stat_start (loop, &passwd);	1384	ev_stat_start (loop, &passwd);
1317		1385
1318		1386
1319	=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...
1320		1388
1321	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
1322	(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
1323	as your process is busy handling sockets or timeouts (or even signals,	1391	count).
1324	imagine) it will not be triggered. But when your process is idle all idle	1392
1325	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
1326	until stopped, that is, or your process receives more events and becomes	1397	iteration - until stopped, that is, or your process receives more events
1327	busy.	1398	and becomes busy again with higher priority stuff.
1328		1399
1329	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
1330	active, the process will not block when waiting for new events.	1401	active, the process will not block when waiting for new events.
1331		1402
1332	Apart from keeping your process non-blocking (which is a useful	1403	Apart from keeping your process non-blocking (which is a useful
…		…
1432		1503
1433	// create io watchers for each fd and a timer before blocking	1504	// create io watchers for each fd and a timer before blocking
1434	static void	1505	static void
1435	adns_prepare_cb (ev_loop loop, ev_prepare w, int revents)	1506	adns_prepare_cb (ev_loop loop, ev_prepare w, int revents)
1436	{	1507	{
1437	int timeout = 3600000;truct pollfd fds [nfd];	1508	int timeout = 3600000;
		1509	struct pollfd fds [nfd];
1438	// actual code will need to loop here and realloc etc.	1510	// actual code will need to loop here and realloc etc.
1439	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));	1511	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));
1440		1512
1441	/* 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 */
1442	ev_timer_init (&tw, 0, timeout * 1e-3);	1514	ev_timer_init (&tw, 0, timeout * 1e-3);
…		…
1676		1748
1677	To use it,	1749	To use it,
1678		1750
1679	#include <ev++.h>	1751	#include <ev++.h>
1680		1752
1681	(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
1682	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
1683	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>.
1684		1757
1685	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++
1686	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).
1687		1768
1688	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:
1689		1770
1690	=over 4	1771	=over 4
1691		1772
…		…
1707		1788
1708	All of those classes have these methods:	1789	All of those classes have these methods:
1709		1790
1710	=over 4	1791	=over 4
1711		1792
1712	=item ev::TYPE::TYPE (object , object::method )	1793	=item ev::TYPE::TYPE ()
1713		1794
1714	=item ev::TYPE::TYPE (object , object::method , struct ev_loop *)	1795	=item ev::TYPE::TYPE (struct ev_loop *)
1715		1796
1716	=item ev::TYPE::~TYPE	1797	=item ev::TYPE::~TYPE
1717		1798
1718	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
1719	the event handler callback to call in this class. The constructor calls	1800	with. If it is omitted, it will use C<EV_DEFAULT>.
1720	C<ev_init> for you, which means you have to call the C<set> method	1801
1721	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
1722	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).
1723		1810
1724	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.
1725		1844
1726	=item w->set (struct ev_loop *)	1845	=item w->set (struct ev_loop *)
1727		1846
1728	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
1729	do this when the watcher is inactive (and not pending either).	1848	do this when the watcher is inactive (and not pending either).
1730		1849
1731	=item w->set ([args])	1850	=item w->set ([args])
1732		1851
1733	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
1734	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
1735	automatically stopped and restarted.	1854	automatically stopped and restarted when reconfiguring it with this
		1855	method.
1736		1856
1737	=item w->start ()	1857	=item w->start ()
1738		1858
1739	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
1740	constructor already takes the loop.	1860	constructor already stores the event loop.
1741		1861
1742	=item w->stop ()	1862	=item w->stop ()
1743		1863
1744	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.
1745		1865
…		…
1770		1890
1771	myclass ();	1891	myclass ();
1772	}	1892	}
1773		1893
1774	myclass::myclass (int fd)	1894	myclass::myclass (int fd)
1775	: io (this, &myclass::io_cb),
1776	idle (this, &myclass::idle_cb)
1777	{	1895	{
		1896	io .set <myclass, &myclass::io_cb > (this);
		1897	idle.set <myclass, &myclass::idle_cb> (this);
		1898
1778	io.start (fd, ev::READ);	1899	io.start (fd, ev::READ);
1779	}	1900	}
1780		1901
1781		1902
1782	=head1 MACRO MAGIC	1903	=head1 MACRO MAGIC
1783		1904
1784	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
1785	C<EV_MULTIPLICITY>. This option determines wether (most) functions and	1906	C<EV_MULTIPLICITY>. This option determines whether (most) functions and
1786	callbacks have an initial C<struct ev_loop *> argument.	1907	callbacks have an initial C<struct ev_loop *> argument.
1787		1908
1788	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
1789	following macros are defined:	1910	following macros are defined:
1790		1911
…		…
1823	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
1824	loop, if multiple loops are supported ("ev loop default").	1945	loop, if multiple loops are supported ("ev loop default").
1825		1946
1826	=back	1947	=back
1827		1948
1828	Example: Declare and initialise a check watcher, working regardless of	1949	Example: Declare and initialise a check watcher, utilising the above
1829	wether multiple loops are supported or not.	1950	macros so it will work regardless of whether multiple loops are supported
		1951	or not.
1830		1952
1831	static void	1953	static void
1832	check_cb (EV_P_ ev_timer *w, int revents)	1954	check_cb (EV_P_ ev_timer *w, int revents)
1833	{	1955	{
1834	ev_check_stop (EV_A_ w);	1956	ev_check_stop (EV_A_ w);
…		…
1836		1958
1837	ev_check check;	1959	ev_check check;
1838	ev_check_init (&check, check_cb);	1960	ev_check_init (&check, check_cb);
1839	ev_check_start (EV_DEFAULT_ &check);	1961	ev_check_start (EV_DEFAULT_ &check);
1840	ev_loop (EV_DEFAULT_ 0);	1962	ev_loop (EV_DEFAULT_ 0);
1841
1842		1963
1843	=head1 EMBEDDING	1964	=head1 EMBEDDING
1844		1965
1845	Libev can (and often is) directly embedded into host	1966	Libev can (and often is) directly embedded into host
1846	applications. Examples of applications that embed it include the Deliantra	1967	applications. Examples of applications that embed it include the Deliantra
…		…
1886	ev_vars.h	2007	ev_vars.h
1887	ev_wrap.h	2008	ev_wrap.h
1888		2009
1889	ev_win32.c required on win32 platforms only	2010	ev_win32.c required on win32 platforms only
1890		2011
1891	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)
1892	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)
1893	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)
1894	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)
1895	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)
1896		2017
…		…
2059	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
2060	additional independent event loops. Otherwise there will be no support	2181	additional independent event loops. Otherwise there will be no support
2061	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
2062	argument. Instead, all functions act on the single default loop.	2183	argument. Instead, all functions act on the single default loop.
2063		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
2064	=item EV_PERIODIC_ENABLE	2202	=item EV_PERIODIC_ENABLE
2065		2203
2066	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
		2205	defined to be C<0>, then they are not. Disabling them saves a few kB of
		2206	code.
		2207
		2208	=item EV_IDLE_ENABLE
		2209
		2210	If undefined or defined to be C<1>, then idle watchers are supported. If
2067	defined to be C<0>, then they are not. Disabling them saves a few kB of	2211	defined to be C<0>, then they are not. Disabling them saves a few kB of
2068	code.	2212	code.
2069		2213
2070	=item EV_EMBED_ENABLE	2214	=item EV_EMBED_ENABLE
2071		2215
…		…
2138	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
2139	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
2140	file.	2284	file.
2141		2285
2142	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
2143	that everybody includes and which overrides some autoconf choices:	2287	that everybody includes and which overrides some configure choices:
2144		2288
		2289	#define EV_MINIMAL 1
2145	#define EV_USE_POLL 0	2290	#define EV_USE_POLL 0
2146	#define EV_MULTIPLICITY 0	2291	#define EV_MULTIPLICITY 0
2147	#define EV_PERIODICS 0	2292	#define EV_PERIODIC_ENABLE 0
		2293	#define EV_STAT_ENABLE 0
		2294	#define EV_FORK_ENABLE 0
2148	#define EV_CONFIG_H <config.h>	2295	#define EV_CONFIG_H <config.h>
		2296	#define EV_MINPRI 0
		2297	#define EV_MAXPRI 0
2149		2298
2150	#include "ev++.h"	2299	#include "ev++.h"
2151		2300
2152	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:
2153		2302
…		…
2159		2308
2160	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
2161	libev will be explained. For complexity discussions about backends see the	2310	libev will be explained. For complexity discussions about backends see the
2162	documentation for C<ev_default_init>.	2311	documentation for C<ev_default_init>.
2163		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
2164	=over 4	2319	=over 4
2165		2320
2166	=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)
2167		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
2168	=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)
2169		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
2170	=item Starting io/check/prepare/idle/signal/child watchers: O(1)	2332	=item Starting io/check/prepare/idle/signal/child watchers: O(1)
2171		2333
		2334	These just add the watcher into an array or at the head of a list.
2172	=item Stopping check/prepare/idle watchers: O(1)	2335	=item Stopping check/prepare/idle watchers: O(1)
2173		2336
2174	=item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))	2337	=item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))
2175		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).
		2342
2176	=item Finding the next timer per loop iteration: O(1)	2343	=item Finding the next timer per loop iteration: O(1)
2177		2344
2178	=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)
2179		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
2180	=item Activating one watcher: O(1)	2350	=item Activating one watcher: O(1)
2181		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
2182	=back	2358	=back
2183		2359
2184		2360
2185	=head1 AUTHOR	2361	=head1 AUTHOR
2186		2362

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Comparing libev/ev.pod (file contents): Revision 1.59 by root, Wed Nov 28 17:32:24 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 1.59 by root, Wed Nov 28 17:32:24 2007 UTC vs.
Revision 1.73 by root, Sat Dec 8 03:53:36 2007 UTC