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

Comparing libev/ev.pod (file contents):
Revision 1.61 by root, Thu Nov 29 12:21:05 2007 UTC vs.
Revision 1.76 by root, Sat Dec 8 15:30:30 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.
		781
		782	=item ev_invoke (loop, ev_TYPE *watcher, int revents)
		783
		784	Invoke the C<watcher> with the given C<loop> and C<revents>. Neither
		785	C<loop> nor C<revents> need to be valid as long as the watcher callback
		786	can deal with that fact.
		787
		788	=item int ev_clear_pending (loop, ev_TYPE *watcher)
		789
		790	If the watcher is pending, this function returns clears its pending status
		791	and returns its C<revents> bitset (as if its callback was invoked). If the
		792	watcher isn't pending it does nothing and returns C<0>.
718		793
719	=back	794	=back
720		795
721		796
722	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER	797	=head2 ASSOCIATING CUSTOM DATA WITH A WATCHER
…		…
828	it is best to always use non-blocking I/O: An extra C<read>(2) returning	903	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.	904	C<EAGAIN> is far preferable to a program hanging until some data arrives.
830		905
831	If you cannot run the fd in non-blocking mode (for example you should not	906	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	907	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	908	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	909	such as poll (fortunately in our Xlib example, Xlib already does this on
835	its own, so its quite safe to use).	910	its own, so its quite safe to use).
836		911
837	=over 4	912	=over 4
838		913
…		…
1321	ev_stat_start (loop, &passwd);	1396	ev_stat_start (loop, &passwd);
1322		1397
1323		1398
1324	=head2 C<ev_idle> - when you've got nothing better to do...	1399	=head2 C<ev_idle> - when you've got nothing better to do...
1325		1400
1326	Idle watchers trigger events when there are no other events are pending	1401	Idle watchers trigger events when no other events of the same or higher
1327	(prepare, check and other idle watchers do not count). That is, as long	1402	priority are pending (prepare, check and other idle watchers do not
1328	as your process is busy handling sockets or timeouts (or even signals,	1403	count).
1329	imagine) it will not be triggered. But when your process is idle all idle	1404
1330	watchers are being called again and again, once per event loop iteration -	1405	That is, as long as your process is busy handling sockets or timeouts
		1406	(or even signals, imagine) of the same or higher priority it will not be
		1407	triggered. But when your process is idle (or only lower-priority watchers
		1408	are pending), the idle watchers are being called once per event loop
1331	until stopped, that is, or your process receives more events and becomes	1409	iteration - until stopped, that is, or your process receives more events
1332	busy.	1410	and becomes busy again with higher priority stuff.
1333		1411
1334	The most noteworthy effect is that as long as any idle watchers are	1412	The most noteworthy effect is that as long as any idle watchers are
1335	active, the process will not block when waiting for new events.	1413	active, the process will not block when waiting for new events.
1336		1414
1337	Apart from keeping your process non-blocking (which is a useful	1415	Apart from keeping your process non-blocking (which is a useful
…		…
1415	parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set>	1493	parameters of any kind. There are C<ev_prepare_set> and C<ev_check_set>
1416	macros, but using them is utterly, utterly and completely pointless.	1494	macros, but using them is utterly, utterly and completely pointless.
1417		1495
1418	=back	1496	=back
1419		1497
1420	Example: To include a library such as adns, you would add IO watchers	1498	There are a number of principal ways to embed other event loops or modules
1421	and a timeout watcher in a prepare handler, as required by libadns, and	1499	into libev. Here are some ideas on how to include libadns into libev
		1500	(there is a Perl module named C<EV::ADNS> that does this, which you could
		1501	use for an actually working example. Another Perl module named C<EV::Glib>
		1502	embeds a Glib main context into libev, and finally, C<Glib::EV> embeds EV
		1503	into the Glib event loop).
		1504
		1505	Method 1: Add IO watchers and a timeout watcher in a prepare handler,
1422	in a check watcher, destroy them and call into libadns. What follows is	1506	and in a check watcher, destroy them and call into libadns. What follows
1423	pseudo-code only of course:	1507	is pseudo-code only of course. This requires you to either use a low
		1508	priority for the check watcher or use C<ev_clear_pending> explicitly, as
		1509	the callbacks for the IO/timeout watchers might not have been called yet.
1424		1510
1425	static ev_io iow [nfd];	1511	static ev_io iow [nfd];
1426	static ev_timer tw;	1512	static ev_timer tw;
1427		1513
1428	static void	1514	static void
1429	io_cb (ev_loop loop, ev_io w, int revents)	1515	io_cb (ev_loop loop, ev_io w, int revents)
1430	{	1516	{
1431	// set the relevant poll flags
1432	// could also call adns_processreadable etc. here
1433	struct pollfd fd = (struct pollfd )w->data;
1434	if (revents & EV_READ ) fd->revents \|= fd->events & POLLIN;
1435	if (revents & EV_WRITE) fd->revents \|= fd->events & POLLOUT;
1436	}	1517	}
1437		1518
1438	// create io watchers for each fd and a timer before blocking	1519	// create io watchers for each fd and a timer before blocking
1439	static void	1520	static void
1440	adns_prepare_cb (ev_loop loop, ev_prepare w, int revents)	1521	adns_prepare_cb (ev_loop loop, ev_prepare w, int revents)
1441	{	1522	{
1442	int timeout = 3600000;truct pollfd fds [nfd];	1523	int timeout = 3600000;
		1524	struct pollfd fds [nfd];
1443	// actual code will need to loop here and realloc etc.	1525	// actual code will need to loop here and realloc etc.
1444	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));	1526	adns_beforepoll (ads, fds, &nfd, &timeout, timeval_from (ev_time ()));
1445		1527
1446	/* the callback is illegal, but won't be called as we stop during check */	1528	/* the callback is illegal, but won't be called as we stop during check */
1447	ev_timer_init (&tw, 0, timeout * 1e-3);	1529	ev_timer_init (&tw, 0, timeout * 1e-3);
1448	ev_timer_start (loop, &tw);	1530	ev_timer_start (loop, &tw);
1449		1531
1450	// create on ev_io per pollfd	1532	// create one ev_io per pollfd
1451	for (int i = 0; i < nfd; ++i)	1533	for (int i = 0; i < nfd; ++i)
1452	{	1534	{
1453	ev_io_init (iow + i, io_cb, fds [i].fd,	1535	ev_io_init (iow + i, io_cb, fds [i].fd,
1454	((fds [i].events & POLLIN ? EV_READ : 0)	1536	((fds [i].events & POLLIN ? EV_READ : 0)
1455	\| (fds [i].events & POLLOUT ? EV_WRITE : 0)));	1537	\| (fds [i].events & POLLOUT ? EV_WRITE : 0)));
1456		1538
1457	fds [i].revents = 0;	1539	fds [i].revents = 0;
1458	iow [i].data = fds + i;
1459	ev_io_start (loop, iow + i);	1540	ev_io_start (loop, iow + i);
1460	}	1541	}
1461	}	1542	}
1462		1543
1463	// stop all watchers after blocking	1544	// stop all watchers after blocking
…		…
1465	adns_check_cb (ev_loop loop, ev_check w, int revents)	1546	adns_check_cb (ev_loop loop, ev_check w, int revents)
1466	{	1547	{
1467	ev_timer_stop (loop, &tw);	1548	ev_timer_stop (loop, &tw);
1468		1549
1469	for (int i = 0; i < nfd; ++i)	1550	for (int i = 0; i < nfd; ++i)
		1551	{
		1552	// set the relevant poll flags
		1553	// could also call adns_processreadable etc. here
		1554	struct pollfd *fd = fds + i;
		1555	int revents = ev_clear_pending (iow + i);
		1556	if (revents & EV_READ ) fd->revents \|= fd->events & POLLIN;
		1557	if (revents & EV_WRITE) fd->revents \|= fd->events & POLLOUT;
		1558
		1559	// now stop the watcher
1470	ev_io_stop (loop, iow + i);	1560	ev_io_stop (loop, iow + i);
		1561	}
1471		1562
1472	adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));	1563	adns_afterpoll (adns, fds, nfd, timeval_from (ev_now (loop));
		1564	}
		1565
		1566	Method 2: This would be just like method 1, but you run C<adns_afterpoll>
		1567	in the prepare watcher and would dispose of the check watcher.
		1568
		1569	Method 3: If the module to be embedded supports explicit event
		1570	notification (adns does), you can also make use of the actual watcher
		1571	callbacks, and only destroy/create the watchers in the prepare watcher.
		1572
		1573	static void
		1574	timer_cb (EV_P_ ev_timer *w, int revents)
		1575	{
		1576	adns_state ads = (adns_state)w->data;
		1577	update_now (EV_A);
		1578
		1579	adns_processtimeouts (ads, &tv_now);
		1580	}
		1581
		1582	static void
		1583	io_cb (EV_P_ ev_io *w, int revents)
		1584	{
		1585	adns_state ads = (adns_state)w->data;
		1586	update_now (EV_A);
		1587
		1588	if (revents & EV_READ ) adns_processreadable (ads, w->fd, &tv_now);
		1589	if (revents & EV_WRITE) adns_processwriteable (ads, w->fd, &tv_now);
		1590	}
		1591
		1592	// do not ever call adns_afterpoll
		1593
		1594	Method 4: Do not use a prepare or check watcher because the module you
		1595	want to embed is too inflexible to support it. Instead, youc na override
		1596	their poll function. The drawback with this solution is that the main
		1597	loop is now no longer controllable by EV. The C<Glib::EV> module does
		1598	this.
		1599
		1600	static gint
		1601	event_poll_func (GPollFD *fds, guint nfds, gint timeout)
		1602	{
		1603	int got_events = 0;
		1604
		1605	for (n = 0; n < nfds; ++n)
		1606	// create/start io watcher that sets the relevant bits in fds[n] and increment got_events
		1607
		1608	if (timeout >= 0)
		1609	// create/start timer
		1610
		1611	// poll
		1612	ev_loop (EV_A_ 0);
		1613
		1614	// stop timer again
		1615	if (timeout >= 0)
		1616	ev_timer_stop (EV_A_ &to);
		1617
		1618	// stop io watchers again - their callbacks should have set
		1619	for (n = 0; n < nfds; ++n)
		1620	ev_io_stop (EV_A_ iow [n]);
		1621
		1622	return got_events;
1473	}	1623	}
1474		1624
1475		1625
1476	=head2 C<ev_embed> - when one backend isn't enough...	1626	=head2 C<ev_embed> - when one backend isn't enough...
1477		1627
…		…
1681		1831
1682	To use it,	1832	To use it,
1683		1833
1684	#include <ev++.h>	1834	#include <ev++.h>
1685		1835
1686	(it is not installed by default). This automatically includes F<ev.h>	1836	This automatically includes F<ev.h> and puts all of its definitions (many
1687	and puts all of its definitions (many of them macros) into the global	1837	of them macros) into the global namespace. All C++ specific things are
1688	namespace. All C++ specific things are put into the C<ev> namespace.	1838	put into the C<ev> namespace. It should support all the same embedding
		1839	options as F<ev.h>, most notably C<EV_MULTIPLICITY>.
1689		1840
1690	It should support all the same embedding options as F<ev.h>, most notably	1841	Care has been taken to keep the overhead low. The only data member the C++
1691	C<EV_MULTIPLICITY>.	1842	classes add (compared to plain C-style watchers) is the event loop pointer
		1843	that the watcher is associated with (or no additional members at all if
		1844	you disable C<EV_MULTIPLICITY> when embedding libev).
		1845
		1846	Currently, functions, and static and non-static member functions can be
		1847	used as callbacks. Other types should be easy to add as long as they only
		1848	need one additional pointer for context. If you need support for other
		1849	types of functors please contact the author (preferably after implementing
		1850	it).
1692		1851
1693	Here is a list of things available in the C<ev> namespace:	1852	Here is a list of things available in the C<ev> namespace:
1694		1853
1695	=over 4	1854	=over 4
1696		1855
…		…
1712		1871
1713	All of those classes have these methods:	1872	All of those classes have these methods:
1714		1873
1715	=over 4	1874	=over 4
1716		1875
1717	=item ev::TYPE::TYPE (object , object::method )	1876	=item ev::TYPE::TYPE ()
1718		1877
1719	=item ev::TYPE::TYPE (object , object::method , struct ev_loop *)	1878	=item ev::TYPE::TYPE (struct ev_loop *)
1720		1879
1721	=item ev::TYPE::~TYPE	1880	=item ev::TYPE::~TYPE
1722		1881
1723	The constructor takes a pointer to an object and a method pointer to	1882	The constructor (optionally) takes an event loop to associate the watcher
1724	the event handler callback to call in this class. The constructor calls	1883	with. If it is omitted, it will use C<EV_DEFAULT>.
1725	C<ev_init> for you, which means you have to call the C<set> method	1884
1726	before starting it. If you do not specify a loop then the constructor	1885	The constructor calls C<ev_init> for you, which means you have to call the
1727	automatically associates the default loop with this watcher.	1886	C<set> method before starting it.
		1887
		1888	It will not set a callback, however: You have to call the templated C<set>
		1889	method to set a callback before you can start the watcher.
		1890
		1891	(The reason why you have to use a method is a limitation in C++ which does
		1892	not allow explicit template arguments for constructors).
1728		1893
1729	The destructor automatically stops the watcher if it is active.	1894	The destructor automatically stops the watcher if it is active.
		1895
		1896	=item w->set<class, &class::method> (object *)
		1897
		1898	This method sets the callback method to call. The method has to have a
		1899	signature of C<void (*)(ev_TYPE &, int)>, it receives the watcher as
		1900	first argument and the C<revents> as second. The object must be given as
		1901	parameter and is stored in the C<data> member of the watcher.
		1902
		1903	This method synthesizes efficient thunking code to call your method from
		1904	the C callback that libev requires. If your compiler can inline your
		1905	callback (i.e. it is visible to it at the place of the C<set> call and
		1906	your compiler is good :), then the method will be fully inlined into the
		1907	thunking function, making it as fast as a direct C callback.
		1908
		1909	Example: simple class declaration and watcher initialisation
		1910
		1911	struct myclass
		1912	{
		1913	void io_cb (ev::io &w, int revents) { }
		1914	}
		1915
		1916	myclass obj;
		1917	ev::io iow;
		1918	iow.set <myclass, &myclass::io_cb> (&obj);
		1919
		1920	=item w->set<function> (void *data = 0)
		1921
		1922	Also sets a callback, but uses a static method or plain function as
		1923	callback. The optional C<data> argument will be stored in the watcher's
		1924	C<data> member and is free for you to use.
		1925
		1926	The prototype of the C<function> must be C<void (*)(ev::TYPE &w, int)>.
		1927
		1928	See the method-C<set> above for more details.
		1929
		1930	Example:
		1931
		1932	static void io_cb (ev::io &w, int revents) { }
		1933	iow.set <io_cb> ();
1730		1934
1731	=item w->set (struct ev_loop *)	1935	=item w->set (struct ev_loop *)
1732		1936
1733	Associates a different C<struct ev_loop> with this watcher. You can only	1937	Associates a different C<struct ev_loop> with this watcher. You can only
1734	do this when the watcher is inactive (and not pending either).	1938	do this when the watcher is inactive (and not pending either).
1735		1939
1736	=item w->set ([args])	1940	=item w->set ([args])
1737		1941
1738	Basically the same as C<ev_TYPE_set>, with the same args. Must be	1942	Basically the same as C<ev_TYPE_set>, with the same args. Must be
1739	called at least once. Unlike the C counterpart, an active watcher gets	1943	called at least once. Unlike the C counterpart, an active watcher gets
1740	automatically stopped and restarted.	1944	automatically stopped and restarted when reconfiguring it with this
		1945	method.
1741		1946
1742	=item w->start ()	1947	=item w->start ()
1743		1948
1744	Starts the watcher. Note that there is no C<loop> argument as the	1949	Starts the watcher. Note that there is no C<loop> argument, as the
1745	constructor already takes the loop.	1950	constructor already stores the event loop.
1746		1951
1747	=item w->stop ()	1952	=item w->stop ()
1748		1953
1749	Stops the watcher if it is active. Again, no C<loop> argument.	1954	Stops the watcher if it is active. Again, no C<loop> argument.
1750		1955
…		…
1775		1980
1776	myclass ();	1981	myclass ();
1777	}	1982	}
1778		1983
1779	myclass::myclass (int fd)	1984	myclass::myclass (int fd)
1780	: io (this, &myclass::io_cb),
1781	idle (this, &myclass::idle_cb)
1782	{	1985	{
		1986	io .set <myclass, &myclass::io_cb > (this);
		1987	idle.set <myclass, &myclass::idle_cb> (this);
		1988
1783	io.start (fd, ev::READ);	1989	io.start (fd, ev::READ);
1784	}	1990	}
1785		1991
1786		1992
1787	=head1 MACRO MAGIC	1993	=head1 MACRO MAGIC
1788		1994
1789	Libev can be compiled with a variety of options, the most fundemantal is	1995	Libev can be compiled with a variety of options, the most fundemantal is
1790	C<EV_MULTIPLICITY>. This option determines wether (most) functions and	1996	C<EV_MULTIPLICITY>. This option determines whether (most) functions and
1791	callbacks have an initial C<struct ev_loop *> argument.	1997	callbacks have an initial C<struct ev_loop *> argument.
1792		1998
1793	To make it easier to write programs that cope with either variant, the	1999	To make it easier to write programs that cope with either variant, the
1794	following macros are defined:	2000	following macros are defined:
1795		2001
…		…
1828	Similar to the other two macros, this gives you the value of the default	2034	Similar to the other two macros, this gives you the value of the default
1829	loop, if multiple loops are supported ("ev loop default").	2035	loop, if multiple loops are supported ("ev loop default").
1830		2036
1831	=back	2037	=back
1832		2038
1833	Example: Declare and initialise a check watcher, working regardless of	2039	Example: Declare and initialise a check watcher, utilising the above
1834	wether multiple loops are supported or not.	2040	macros so it will work regardless of whether multiple loops are supported
		2041	or not.
1835		2042
1836	static void	2043	static void
1837	check_cb (EV_P_ ev_timer *w, int revents)	2044	check_cb (EV_P_ ev_timer *w, int revents)
1838	{	2045	{
1839	ev_check_stop (EV_A_ w);	2046	ev_check_stop (EV_A_ w);
…		…
1841		2048
1842	ev_check check;	2049	ev_check check;
1843	ev_check_init (&check, check_cb);	2050	ev_check_init (&check, check_cb);
1844	ev_check_start (EV_DEFAULT_ &check);	2051	ev_check_start (EV_DEFAULT_ &check);
1845	ev_loop (EV_DEFAULT_ 0);	2052	ev_loop (EV_DEFAULT_ 0);
1846
1847		2053
1848	=head1 EMBEDDING	2054	=head1 EMBEDDING
1849		2055
1850	Libev can (and often is) directly embedded into host	2056	Libev can (and often is) directly embedded into host
1851	applications. Examples of applications that embed it include the Deliantra	2057	applications. Examples of applications that embed it include the Deliantra
…		…
1891	ev_vars.h	2097	ev_vars.h
1892	ev_wrap.h	2098	ev_wrap.h
1893		2099
1894	ev_win32.c required on win32 platforms only	2100	ev_win32.c required on win32 platforms only
1895		2101
1896	ev_select.c only when select backend is enabled (which is by default)	2102	ev_select.c only when select backend is enabled (which is enabled by default)
1897	ev_poll.c only when poll backend is enabled (disabled by default)	2103	ev_poll.c only when poll backend is enabled (disabled by default)
1898	ev_epoll.c only when the epoll backend is enabled (disabled by default)	2104	ev_epoll.c only when the epoll backend is enabled (disabled by default)
1899	ev_kqueue.c only when the kqueue backend is enabled (disabled by default)	2105	ev_kqueue.c only when the kqueue backend is enabled (disabled by default)
1900	ev_port.c only when the solaris port backend is enabled (disabled by default)	2106	ev_port.c only when the solaris port backend is enabled (disabled by default)
1901		2107
…		…
2064	will have the C<struct ev_loop *> as first argument, and you can create	2270	will have the C<struct ev_loop *> as first argument, and you can create
2065	additional independent event loops. Otherwise there will be no support	2271	additional independent event loops. Otherwise there will be no support
2066	for multiple event loops and there is no first event loop pointer	2272	for multiple event loops and there is no first event loop pointer
2067	argument. Instead, all functions act on the single default loop.	2273	argument. Instead, all functions act on the single default loop.
2068		2274
		2275	=item EV_MINPRI
		2276
		2277	=item EV_MAXPRI
		2278
		2279	The range of allowed priorities. C<EV_MINPRI> must be smaller or equal to
		2280	C<EV_MAXPRI>, but otherwise there are no non-obvious limitations. You can
		2281	provide for more priorities by overriding those symbols (usually defined
		2282	to be C<-2> and C<2>, respectively).
		2283
		2284	When doing priority-based operations, libev usually has to linearly search
		2285	all the priorities, so having many of them (hundreds) uses a lot of space
		2286	and time, so using the defaults of five priorities (-2 .. +2) is usually
		2287	fine.
		2288
		2289	If your embedding app does not need any priorities, defining these both to
		2290	C<0> will save some memory and cpu.
		2291
2069	=item EV_PERIODIC_ENABLE	2292	=item EV_PERIODIC_ENABLE
2070		2293
2071	If undefined or defined to be C<1>, then periodic timers are supported. If	2294	If undefined or defined to be C<1>, then periodic timers are supported. If
		2295	defined to be C<0>, then they are not. Disabling them saves a few kB of
		2296	code.
		2297
		2298	=item EV_IDLE_ENABLE
		2299
		2300	If undefined or defined to be C<1>, then idle watchers are supported. If
2072	defined to be C<0>, then they are not. Disabling them saves a few kB of	2301	defined to be C<0>, then they are not. Disabling them saves a few kB of
2073	code.	2302	code.
2074		2303
2075	=item EV_EMBED_ENABLE	2304	=item EV_EMBED_ENABLE
2076		2305
…		…
2143	interface) and F<EV.xs> (implementation) files. Only the F<EV.xs> file	2372	interface) and F<EV.xs> (implementation) files. Only the F<EV.xs> file
2144	will be compiled. It is pretty complex because it provides its own header	2373	will be compiled. It is pretty complex because it provides its own header
2145	file.	2374	file.
2146		2375
2147	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file	2376	The usage in rxvt-unicode is simpler. It has a F<ev_cpp.h> header file
2148	that everybody includes and which overrides some autoconf choices:	2377	that everybody includes and which overrides some configure choices:
2149		2378
		2379	#define EV_MINIMAL 1
2150	#define EV_USE_POLL 0	2380	#define EV_USE_POLL 0
2151	#define EV_MULTIPLICITY 0	2381	#define EV_MULTIPLICITY 0
2152	#define EV_PERIODICS 0	2382	#define EV_PERIODIC_ENABLE 0
		2383	#define EV_STAT_ENABLE 0
		2384	#define EV_FORK_ENABLE 0
2153	#define EV_CONFIG_H <config.h>	2385	#define EV_CONFIG_H <config.h>
		2386	#define EV_MINPRI 0
		2387	#define EV_MAXPRI 0
2154		2388
2155	#include "ev++.h"	2389	#include "ev++.h"
2156		2390
2157	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:	2391	And a F<ev_cpp.C> implementation file that contains libev proper and is compiled:
2158		2392
…		…
2164		2398
2165	In this section the complexities of (many of) the algorithms used inside	2399	In this section the complexities of (many of) the algorithms used inside
2166	libev will be explained. For complexity discussions about backends see the	2400	libev will be explained. For complexity discussions about backends see the
2167	documentation for C<ev_default_init>.	2401	documentation for C<ev_default_init>.
2168		2402
		2403	All of the following are about amortised time: If an array needs to be
		2404	extended, libev needs to realloc and move the whole array, but this
		2405	happens asymptotically never with higher number of elements, so O(1) might
		2406	mean it might do a lengthy realloc operation in rare cases, but on average
		2407	it is much faster and asymptotically approaches constant time.
		2408
2169	=over 4	2409	=over 4
2170		2410
2171	=item Starting and stopping timer/periodic watchers: O(log skipped_other_timers)	2411	=item Starting and stopping timer/periodic watchers: O(log skipped_other_timers)
2172		2412
		2413	This means that, when you have a watcher that triggers in one hour and
		2414	there are 100 watchers that would trigger before that then inserting will
		2415	have to skip those 100 watchers.
		2416
2173	=item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)	2417	=item Changing timer/periodic watchers (by autorepeat, again): O(log skipped_other_timers)
2174		2418
		2419	That means that for changing a timer costs less than removing/adding them
		2420	as only the relative motion in the event queue has to be paid for.
		2421
2175	=item Starting io/check/prepare/idle/signal/child watchers: O(1)	2422	=item Starting io/check/prepare/idle/signal/child watchers: O(1)
2176		2423
		2424	These just add the watcher into an array or at the head of a list.
2177	=item Stopping check/prepare/idle watchers: O(1)	2425	=item Stopping check/prepare/idle watchers: O(1)
2178		2426
2179	=item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))	2427	=item Stopping an io/signal/child watcher: O(number_of_watchers_for_this_(fd/signal/pid % EV_PID_HASHSIZE))
2180		2428
		2429	These watchers are stored in lists then need to be walked to find the
		2430	correct watcher to remove. The lists are usually short (you don't usually
		2431	have many watchers waiting for the same fd or signal).
		2432
2181	=item Finding the next timer per loop iteration: O(1)	2433	=item Finding the next timer per loop iteration: O(1)
2182		2434
2183	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)	2435	=item Each change on a file descriptor per loop iteration: O(number_of_watchers_for_this_fd)
2184		2436
		2437	A change means an I/O watcher gets started or stopped, which requires
		2438	libev to recalculate its status (and possibly tell the kernel).
		2439
2185	=item Activating one watcher: O(1)	2440	=item Activating one watcher: O(1)
2186		2441
		2442	=item Priority handling: O(number_of_priorities)
		2443
		2444	Priorities are implemented by allocating some space for each
		2445	priority. When doing priority-based operations, libev usually has to
		2446	linearly search all the priorities.
		2447
2187	=back	2448	=back
2188		2449
2189		2450
2190	=head1 AUTHOR	2451	=head1 AUTHOR
2191		2452

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Comparing libev/ev.pod (file contents): Revision 1.61 by root, Thu Nov 29 12:21:05 2007 UTC vs. Revision 1.76 by root, Sat Dec 8 15:30:30 2007 UTC

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Comparing libev/ev.pod (file contents):
Revision 1.61 by root, Thu Nov 29 12:21:05 2007 UTC vs.
Revision 1.76 by root, Sat Dec 8 15:30:30 2007 UTC