[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 1.72 by root, Fri Dec 7 20:19:16 2007 UTC

…		…
47		47
48	return 0;	48	return 0;
49	}	49	}
50		50
51	=head1 DESCRIPTION	51	=head1 DESCRIPTION
		52
		53	The newest version of this document is also available as a html-formatted
		54	web page you might find easier to navigate when reading it for the first
		55	time: L<http://cvs.schmorp.de/libev/ev.html>.
52		56
53	Libev is an event loop: you register interest in certain events (such as a	57	Libev is an event loop: you register interest in certain events (such as a
54	file descriptor being readable or a timeout occuring), and it will manage	58	file descriptor being readable or a timeout occuring), and it will manage
55	these event sources and provide your program with events.	59	these event sources and provide your program with events.
56		60
…		…
63	details of the event, and then hand it over to libev by I<starting> the	67	details of the event, and then hand it over to libev by I<starting> the
64	watcher.	68	watcher.
65		69
66	=head1 FEATURES	70	=head1 FEATURES
67		71
68	Libev supports C<select>, C<poll>, the linux-specific C<epoll>, the	72	Libev supports C<select>, C<poll>, the Linux-specific C<epoll>, the
69	bsd-specific C<kqueue> and the solaris-specific event port mechanisms	73	BSD-specific C<kqueue> and the Solaris-specific event port mechanisms
70	for file descriptor events (C<ev_io>), relative timers (C<ev_timer>),	74	for file descriptor events (C<ev_io>), the Linux C<inotify> interface
		75	(for C<ev_stat>), relative timers (C<ev_timer>), absolute timers
71	absolute timers with customised rescheduling (C<ev_periodic>), synchronous	76	with customised rescheduling (C<ev_periodic>), synchronous signals
72	signals (C<ev_signal>), process status change events (C<ev_child>), and	77	(C<ev_signal>), process status change events (C<ev_child>), and event
73	event watchers dealing with the event loop mechanism itself (C<ev_idle>,	78	watchers dealing with the event loop mechanism itself (C<ev_idle>,
74	C<ev_embed>, C<ev_prepare> and C<ev_check> watchers) as well as	79	C<ev_embed>, C<ev_prepare> and C<ev_check> watchers) as well as
75	file watchers (C<ev_stat>) and even limited support for fork events	80	file watchers (C<ev_stat>) and even limited support for fork events
76	(C<ev_fork>).	81	(C<ev_fork>).
77		82
78	It also is quite fast (see this	83	It also is quite fast (see this
…		…
162	C<ev_embeddable_backends () & ev_supported_backends ()>, likewise for	167	C<ev_embeddable_backends () & ev_supported_backends ()>, likewise for
163	recommended ones.	168	recommended ones.
164		169
165	See the description of C<ev_embed> watchers for more info.	170	See the description of C<ev_embed> watchers for more info.
166		171
167	=item ev_set_allocator (void (cb)(void *ptr, size_t size))	172	=item ev_set_allocator (void (cb)(void *ptr, long size))
168		173
169	Sets the allocation function to use (the prototype and semantics are	174	Sets the allocation function to use (the prototype is similar - the
170	identical to the realloc C function). It is used to allocate and free	175	semantics is identical - to the realloc C function). It is used to
171	memory (no surprises here). If it returns zero when memory needs to be	176	allocate and free memory (no surprises here). If it returns zero when
172	allocated, the library might abort or take some potentially destructive	177	memory needs to be allocated, the library might abort or take some
173	action. The default is your system realloc function.	178	potentially destructive action. The default is your system realloc
		179	function.
174		180
175	You could override this function in high-availability programs to, say,	181	You could override this function in high-availability programs to, say,
176	free some memory if it cannot allocate memory, to use a special allocator,	182	free some memory if it cannot allocate memory, to use a special allocator,
177	or even to sleep a while and retry until some memory is available.	183	or even to sleep a while and retry until some memory is available.
178		184
…		…
264	C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will	270	C<LIBEV_FLAGS>. Otherwise (the default), this environment variable will
265	override the flags completely if it is found in the environment. This is	271	override the flags completely if it is found in the environment. This is
266	useful to try out specific backends to test their performance, or to work	272	useful to try out specific backends to test their performance, or to work
267	around bugs.	273	around bugs.
268		274
		275	=item C<EVFLAG_FORKCHECK>
		276
		277	Instead of calling C<ev_default_fork> or C<ev_loop_fork> manually after
		278	a fork, you can also make libev check for a fork in each iteration by
		279	enabling this flag.
		280
		281	This works by calling C<getpid ()> on every iteration of the loop,
		282	and thus this might slow down your event loop if you do a lot of loop
		283	iterations and little real work, but is usually not noticeable (on my
		284	Linux system for example, C<getpid> is actually a simple 5-insn sequence
		285	without a syscall and thus I<very> fast, but my Linux system also has
		286	C<pthread_atfork> which is even faster).
		287
		288	The big advantage of this flag is that you can forget about fork (and
		289	forget about forgetting to tell libev about forking) when you use this
		290	flag.
		291
		292	This flag setting cannot be overriden or specified in the C<LIBEV_FLAGS>
		293	environment variable.
		294
269	=item C<EVBACKEND_SELECT> (value 1, portable select backend)	295	=item C<EVBACKEND_SELECT> (value 1, portable select backend)
270		296
271	This is your standard select(2) backend. Not I<completely> standard, as	297	This is your standard select(2) backend. Not I<completely> standard, as
272	libev tries to roll its own fd_set with no limits on the number of fds,	298	libev tries to roll its own fd_set with no limits on the number of fds,
273	but if that fails, expect a fairly low limit on the number of fds when	299	but if that fails, expect a fairly low limit on the number of fds when
…		…
407	=item ev_loop_fork (loop)	433	=item ev_loop_fork (loop)
408		434
409	Like C<ev_default_fork>, but acts on an event loop created by	435	Like C<ev_default_fork>, but acts on an event loop created by
410	C<ev_loop_new>. Yes, you have to call this on every allocated event loop	436	C<ev_loop_new>. Yes, you have to call this on every allocated event loop
411	after fork, and how you do this is entirely your own problem.	437	after fork, and how you do this is entirely your own problem.
		438
		439	=item unsigned int ev_loop_count (loop)
		440
		441	Returns the count of loop iterations for the loop, which is identical to
		442	the number of times libev did poll for new events. It starts at C<0> and
		443	happily wraps around with enough iterations.
		444
		445	This value can sometimes be useful as a generation counter of sorts (it
		446	"ticks" the number of loop iterations), as it roughly corresponds with
		447	C<ev_prepare> and C<ev_check> calls.
412		448
413	=item unsigned int ev_backend (loop)	449	=item unsigned int ev_backend (loop)
414		450
415	Returns one of the C<EVBACKEND_*> flags indicating the event backend in	451	Returns one of the C<EVBACKEND_*> flags indicating the event backend in
416	use.	452	use.
…		…
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);
…		…
1669		1744
1670	To use it,	1745	To use it,
1671		1746
1672	#include <ev++.h>	1747	#include <ev++.h>
1673		1748
1674	(it is not installed by default). This automatically includes F<ev.h>	1749	This automatically includes F<ev.h> and puts all of its definitions (many
1675	and puts all of its definitions (many of them macros) into the global	1750	of them macros) into the global namespace. All C++ specific things are
1676	namespace. All C++ specific things are put into the C<ev> namespace.	1751	put into the C<ev> namespace. It should support all the same embedding
		1752	options as F<ev.h>, most notably C<EV_MULTIPLICITY>.
1677		1753
1678	It should support all the same embedding options as F<ev.h>, most notably	1754	Care has been taken to keep the overhead low. The only data member the C++
1679	C<EV_MULTIPLICITY>.	1755	classes add (compared to plain C-style watchers) is the event loop pointer
		1756	that the watcher is associated with (or no additional members at all if
		1757	you disable C<EV_MULTIPLICITY> when embedding libev).
		1758
		1759	Currently, functions, and static and non-static member functions can be
		1760	used as callbacks. Other types should be easy to add as long as they only
		1761	need one additional pointer for context. If you need support for other
		1762	types of functors please contact the author (preferably after implementing
		1763	it).
1680		1764
1681	Here is a list of things available in the C<ev> namespace:	1765	Here is a list of things available in the C<ev> namespace:
1682		1766
1683	=over 4	1767	=over 4
1684		1768
…		…
1700		1784
1701	All of those classes have these methods:	1785	All of those classes have these methods:
1702		1786
1703	=over 4	1787	=over 4
1704		1788
1705	=item ev::TYPE::TYPE (object , object::method )	1789	=item ev::TYPE::TYPE ()
1706		1790
1707	=item ev::TYPE::TYPE (object , object::method , struct ev_loop *)	1791	=item ev::TYPE::TYPE (struct ev_loop *)
1708		1792
1709	=item ev::TYPE::~TYPE	1793	=item ev::TYPE::~TYPE
1710		1794
1711	The constructor takes a pointer to an object and a method pointer to	1795	The constructor (optionally) takes an event loop to associate the watcher
1712	the event handler callback to call in this class. The constructor calls	1796	with. If it is omitted, it will use C<EV_DEFAULT>.
1713	C<ev_init> for you, which means you have to call the C<set> method	1797
1714	before starting it. If you do not specify a loop then the constructor	1798	The constructor calls C<ev_init> for you, which means you have to call the
1715	automatically associates the default loop with this watcher.	1799	C<set> method before starting it.
		1800
		1801	It will not set a callback, however: You have to call the templated C<set>
		1802	method to set a callback before you can start the watcher.
		1803
		1804	(The reason why you have to use a method is a limitation in C++ which does
		1805	not allow explicit template arguments for constructors).
1716		1806
1717	The destructor automatically stops the watcher if it is active.	1807	The destructor automatically stops the watcher if it is active.
		1808
		1809	=item w->set<class, &class::method> (object *)
		1810
		1811	This method sets the callback method to call. The method has to have a
		1812	signature of C<void (*)(ev_TYPE &, int)>, it receives the watcher as
		1813	first argument and the C<revents> as second. The object must be given as
		1814	parameter and is stored in the C<data> member of the watcher.
		1815
		1816	This method synthesizes efficient thunking code to call your method from
		1817	the C callback that libev requires. If your compiler can inline your
		1818	callback (i.e. it is visible to it at the place of the C<set> call and
		1819	your compiler is good :), then the method will be fully inlined into the
		1820	thunking function, making it as fast as a direct C callback.
		1821
		1822	Example: simple class declaration and watcher initialisation
		1823
		1824	struct myclass
		1825	{
		1826	void io_cb (ev::io &w, int revents) { }
		1827	}
		1828
		1829	myclass obj;
		1830	ev::io iow;
		1831	iow.set <myclass, &myclass::io_cb> (&obj);
		1832
		1833	=item w->set (void (function)(watcher &w, int), void data = 0)
		1834
		1835	Also sets a callback, but uses a static method or plain function as
		1836	callback. The optional C<data> argument will be stored in the watcher's
		1837	C<data> member and is free for you to use.
		1838
		1839	See the method-C<set> above for more details.
1718		1840
1719	=item w->set (struct ev_loop *)	1841	=item w->set (struct ev_loop *)
1720		1842
1721	Associates a different C<struct ev_loop> with this watcher. You can only	1843	Associates a different C<struct ev_loop> with this watcher. You can only
1722	do this when the watcher is inactive (and not pending either).	1844	do this when the watcher is inactive (and not pending either).
1723		1845
1724	=item w->set ([args])	1846	=item w->set ([args])
1725		1847
1726	Basically the same as C<ev_TYPE_set>, with the same args. Must be	1848	Basically the same as C<ev_TYPE_set>, with the same args. Must be
1727	called at least once. Unlike the C counterpart, an active watcher gets	1849	called at least once. Unlike the C counterpart, an active watcher gets
1728	automatically stopped and restarted.	1850	automatically stopped and restarted when reconfiguring it with this
		1851	method.
1729		1852
1730	=item w->start ()	1853	=item w->start ()
1731		1854
1732	Starts the watcher. Note that there is no C<loop> argument as the	1855	Starts the watcher. Note that there is no C<loop> argument, as the
1733	constructor already takes the loop.	1856	constructor already stores the event loop.
1734		1857
1735	=item w->stop ()	1858	=item w->stop ()
1736		1859
1737	Stops the watcher if it is active. Again, no C<loop> argument.	1860	Stops the watcher if it is active. Again, no C<loop> argument.
1738		1861
…		…
1763		1886
1764	myclass ();	1887	myclass ();
1765	}	1888	}
1766		1889
1767	myclass::myclass (int fd)	1890	myclass::myclass (int fd)
1768	: io (this, &myclass::io_cb),
1769	idle (this, &myclass::idle_cb)
1770	{	1891	{
		1892	io .set <myclass, &myclass::io_cb > (this);
		1893	idle.set <myclass, &myclass::idle_cb> (this);
		1894
1771	io.start (fd, ev::READ);	1895	io.start (fd, ev::READ);
1772	}	1896	}
1773		1897
1774		1898
1775	=head1 MACRO MAGIC	1899	=head1 MACRO MAGIC
1776		1900
1777	Libev can be compiled with a variety of options, the most fundemantal is	1901	Libev can be compiled with a variety of options, the most fundemantal is
1778	C<EV_MULTIPLICITY>. This option determines wether (most) functions and	1902	C<EV_MULTIPLICITY>. This option determines whether (most) functions and
1779	callbacks have an initial C<struct ev_loop *> argument.	1903	callbacks have an initial C<struct ev_loop *> argument.
1780		1904
1781	To make it easier to write programs that cope with either variant, the	1905	To make it easier to write programs that cope with either variant, the
1782	following macros are defined:	1906	following macros are defined:
1783		1907
…		…
1816	Similar to the other two macros, this gives you the value of the default	1940	Similar to the other two macros, this gives you the value of the default
1817	loop, if multiple loops are supported ("ev loop default").	1941	loop, if multiple loops are supported ("ev loop default").
1818		1942
1819	=back	1943	=back
1820		1944
1821	Example: Declare and initialise a check watcher, working regardless of	1945	Example: Declare and initialise a check watcher, utilising the above
1822	wether multiple loops are supported or not.	1946	macros so it will work regardless of whether multiple loops are supported
		1947	or not.
1823		1948
1824	static void	1949	static void
1825	check_cb (EV_P_ ev_timer *w, int revents)	1950	check_cb (EV_P_ ev_timer *w, int revents)
1826	{	1951	{
1827	ev_check_stop (EV_A_ w);	1952	ev_check_stop (EV_A_ w);
…		…
1829		1954
1830	ev_check check;	1955	ev_check check;
1831	ev_check_init (&check, check_cb);	1956	ev_check_init (&check, check_cb);
1832	ev_check_start (EV_DEFAULT_ &check);	1957	ev_check_start (EV_DEFAULT_ &check);
1833	ev_loop (EV_DEFAULT_ 0);	1958	ev_loop (EV_DEFAULT_ 0);
1834
1835		1959
1836	=head1 EMBEDDING	1960	=head1 EMBEDDING
1837		1961
1838	Libev can (and often is) directly embedded into host	1962	Libev can (and often is) directly embedded into host
1839	applications. Examples of applications that embed it include the Deliantra	1963	applications. Examples of applications that embed it include the Deliantra
…		…
1879	ev_vars.h	2003	ev_vars.h
1880	ev_wrap.h	2004	ev_wrap.h
1881		2005
1882	ev_win32.c required on win32 platforms only	2006	ev_win32.c required on win32 platforms only
1883		2007
1884	ev_select.c only when select backend is enabled (which is by default)	2008	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)	2009	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)	2010	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)	2011	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)	2012	ev_port.c only when the solaris port backend is enabled (disabled by default)
1889		2013
…		…
2014		2138
2015	=item EV_USE_DEVPOLL	2139	=item EV_USE_DEVPOLL
2016		2140
2017	reserved for future expansion, works like the USE symbols above.	2141	reserved for future expansion, works like the USE symbols above.
2018		2142
		2143	=item EV_USE_INOTIFY
		2144
		2145	If defined to be C<1>, libev will compile in support for the Linux inotify
		2146	interface to speed up C<ev_stat> watchers. Its actual availability will
		2147	be detected at runtime.
		2148
2019	=item EV_H	2149	=item EV_H
2020		2150
2021	The name of the F<ev.h> header file used to include it. The default if	2151	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	2152	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.	2153	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	2176	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	2177	additional independent event loops. Otherwise there will be no support
2048	for multiple event loops and there is no first event loop pointer	2178	for multiple event loops and there is no first event loop pointer
2049	argument. Instead, all functions act on the single default loop.	2179	argument. Instead, all functions act on the single default loop.
2050		2180
		2181	=item EV_MINPRI
		2182
		2183	=item EV_MAXPRI
		2184
		2185	The range of allowed priorities. C<EV_MINPRI> must be smaller or equal to
		2186	C<EV_MAXPRI>, but otherwise there are no non-obvious limitations. You can
		2187	provide for more priorities by overriding those symbols (usually defined
		2188	to be C<-2> and C<2>, respectively).
		2189
		2190	When doing priority-based operations, libev usually has to linearly search
		2191	all the priorities, so having many of them (hundreds) uses a lot of space
		2192	and time, so using the defaults of five priorities (-2 .. +2) is usually
		2193	fine.
		2194
		2195	If your embedding app does not need any priorities, defining these both to
		2196	C<0> will save some memory and cpu.
		2197
2051	=item EV_PERIODIC_ENABLE	2198	=item EV_PERIODIC_ENABLE
2052		2199
2053	If undefined or defined to be C<1>, then periodic timers are supported. If	2200	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	2201	defined to be C<0>, then they are not. Disabling them saves a few kB of
2055	code.	2202	code.
2056		2203
		2204	=item EV_IDLE_ENABLE
		2205
		2206	If undefined or defined to be C<1>, then idle watchers are supported. If
		2207	defined to be C<0>, then they are not. Disabling them saves a few kB of
		2208	code.
		2209
2057	=item EV_EMBED_ENABLE	2210	=item EV_EMBED_ENABLE
2058		2211
2059	If undefined or defined to be C<1>, then embed watchers are supported. If	2212	If undefined or defined to be C<1>, then embed watchers are supported. If
2060	defined to be C<0>, then they are not.	2213	defined to be C<0>, then they are not.
2061		2214
…		…
2078	=item EV_PID_HASHSIZE	2231	=item EV_PID_HASHSIZE
2079		2232
2080	C<ev_child> watchers use a small hash table to distribute workload by	2233	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	2234	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	2235	than enough. If you need to manage thousands of children you might want to
2083	increase this value.	2236	increase this value (I<must> be a power of two).
		2237
		2238	=item EV_INOTIFY_HASHSIZE
		2239
		2240	C<ev_staz> watchers use a small hash table to distribute workload by
		2241	inotify watch id. The default size is C<16> (or C<1> with C<EV_MINIMAL>),
		2242	usually more than enough. If you need to manage thousands of C<ev_stat>
		2243	watchers you might want to increase this value (I<must> be a power of
		2244	two).
2084		2245
2085	=item EV_COMMON	2246	=item EV_COMMON
2086		2247
2087	By default, all watchers have a C<void *data> member. By redefining	2248	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	2249	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	2278	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	2279	will be compiled. It is pretty complex because it provides its own header
2119	file.	2280	file.
2120		2281
2121	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file	2282	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:	2283	that everybody includes and which overrides some configure choices:
2123		2284
		2285	#define EV_MINIMAL 1
2124	#define EV_USE_POLL 0	2286	#define EV_USE_POLL 0
2125	#define EV_MULTIPLICITY 0	2287	#define EV_MULTIPLICITY 0
2126	#define EV_PERIODICS 0	2288	#define EV_PERIODIC_ENABLE 0
		2289	#define EV_STAT_ENABLE 0
		2290	#define EV_FORK_ENABLE 0
2127	#define EV_CONFIG_H <config.h>	2291	#define EV_CONFIG_H <config.h>
		2292	#define EV_MINPRI 0
		2293	#define EV_MAXPRI 0
2128		2294
2129	#include "ev++.h"	2295	#include "ev++.h"
2130		2296
2131	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:	2297	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:
2132		2298
…		…
2138		2304
2139	In this section the complexities of (many of) the algorithms used inside	2305	In this section the complexities of (many of) the algorithms used inside
2140	libev will be explained. For complexity discussions about backends see the	2306	libev will be explained. For complexity discussions about backends see the
2141	documentation for C<ev_default_init>.	2307	documentation for C<ev_default_init>.
2142		2308
		2309	All of the following are about amortised time: If an array needs to be
		2310	extended, libev needs to realloc and move the whole array, but this
		2311	happens asymptotically never with higher number of elements, so O(1) might
		2312	mean it might do a lengthy realloc operation in rare cases, but on average
		2313	it is much faster and asymptotically approaches constant time.
		2314
2143	=over 4	2315	=over 4
2144		2316
2145	=item Starting and stopping timer/periodic watchers: O(log skipped_other_timers)	2317	=item Starting and stopping timer/periodic watchers: O(log skipped_other_timers)
2146		2318
		2319	This means that, when you have a watcher that triggers in one hour and
		2320	there are 100 watchers that would trigger before that then inserting will
		2321	have to skip those 100 watchers.
		2322
2147	=item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)	2323	=item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)
2148		2324
		2325	That means that for changing a timer costs less than removing/adding them
		2326	as only the relative motion in the event queue has to be paid for.
		2327
2149	=item Starting io/check/prepare/idle/signal/child watchers: O(1)	2328	=item Starting io/check/prepare/idle/signal/child watchers: O(1)
2150		2329
		2330	These just add the watcher into an array or at the head of a list.
2151	=item Stopping check/prepare/idle watchers: O(1)	2331	=item Stopping check/prepare/idle watchers: O(1)
2152		2332
2153	=item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % 16))	2333	=item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))
		2334
		2335	These watchers are stored in lists then need to be walked to find the
		2336	correct watcher to remove. The lists are usually short (you don't usually
		2337	have many watchers waiting for the same fd or signal).
2154		2338
2155	=item Finding the next timer per loop iteration: O(1)	2339	=item Finding the next timer per loop iteration: O(1)
2156		2340
2157	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)	2341	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)
2158		2342
		2343	A change means an I/O watcher gets started or stopped, which requires
		2344	libev to recalculate its status (and possibly tell the kernel).
		2345
2159	=item Activating one watcher: O(1)	2346	=item Activating one watcher: O(1)
2160		2347
		2348	=item Priority handling: O(number_of_priorities)
		2349
		2350	Priorities are implemented by allocating some space for each
		2351	priority. When doing priority-based operations, libev usually has to
		2352	linearly search all the priorities.
		2353
2161	=back	2354	=back
2162		2355
2163		2356
2164	=head1 AUTHOR	2357	=head1 AUTHOR
2165		2358

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Comparing libev/ev.pod (file contents): Revision 1.55 by root, Tue Nov 27 20:38:07 2007 UTC vs. Revision 1.72 by root, Fri Dec 7 20:19:16 2007 UTC

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Comparing libev/ev.pod (file contents):
Revision 1.55 by root, Tue Nov 27 20:38:07 2007 UTC vs.
Revision 1.72 by root, Fri Dec 7 20:19:16 2007 UTC