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

Comparing libev/ev.pod (file contents):
Revision 1.132 by root, Wed Feb 20 17:45:29 2008 UTC vs.
Revision 1.150 by root, Tue May 6 23:34:16 2008 UTC

…		…
6		6
7	#include <ev.h>	7	#include <ev.h>
8		8
9	=head2 EXAMPLE PROGRAM	9	=head2 EXAMPLE PROGRAM
10		10
		11	// a single header file is required
11	#include <ev.h>	12	#include <ev.h>
12		13
		14	// every watcher type has its own typedef'd struct
		15	// with the name ev_<type>
13	ev_io stdin_watcher;	16	ev_io stdin_watcher;
14	ev_timer timeout_watcher;	17	ev_timer timeout_watcher;
15		18
		19	// all watcher callbacks have a similar signature
16	/* called when data readable on stdin */	20	// this callback is called when data is readable on stdin
17	static void	21	static void
18	stdin_cb (EV_P_ struct ev_io *w, int revents)	22	stdin_cb (EV_P_ struct ev_io *w, int revents)
19	{	23	{
20	/* puts ("stdin ready"); */	24	puts ("stdin ready");
21	ev_io_stop (EV_A_ w); /* just a syntax example */	25	// for one-shot events, one must manually stop the watcher
22	ev_unloop (EV_A_ EVUNLOOP_ALL); /* leave all loop calls */	26	// with its corresponding stop function.
		27	ev_io_stop (EV_A_ w);
		28
		29	// this causes all nested ev_loop's to stop iterating
		30	ev_unloop (EV_A_ EVUNLOOP_ALL);
23	}	31	}
24		32
		33	// another callback, this time for a time-out
25	static void	34	static void
26	timeout_cb (EV_P_ struct ev_timer *w, int revents)	35	timeout_cb (EV_P_ struct ev_timer *w, int revents)
27	{	36	{
28	/* puts ("timeout"); */	37	puts ("timeout");
29	ev_unloop (EV_A_ EVUNLOOP_ONE); /* leave one loop call */	38	// this causes the innermost ev_loop to stop iterating
		39	ev_unloop (EV_A_ EVUNLOOP_ONE);
30	}	40	}
31		41
32	int	42	int
33	main (void)	43	main (void)
34	{	44	{
		45	// use the default event loop unless you have special needs
35	struct ev_loop *loop = ev_default_loop (0);	46	struct ev_loop *loop = ev_default_loop (0);
36		47
37	/* initialise an io watcher, then start it */	48	// initialise an io watcher, then start it
		49	// this one will watch for stdin to become readable
38	ev_io_init (&stdin_watcher, stdin_cb, /STDIN_FILENO/ 0, EV_READ);	50	ev_io_init (&stdin_watcher, stdin_cb, /STDIN_FILENO/ 0, EV_READ);
39	ev_io_start (loop, &stdin_watcher);	51	ev_io_start (loop, &stdin_watcher);
40		52
		53	// initialise a timer watcher, then start it
41	/* simple non-repeating 5.5 second timeout */	54	// simple non-repeating 5.5 second timeout
42	ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.);	55	ev_timer_init (&timeout_watcher, timeout_cb, 5.5, 0.);
43	ev_timer_start (loop, &timeout_watcher);	56	ev_timer_start (loop, &timeout_watcher);
44		57
45	/* loop till timeout or data ready */	58	// now wait for events to arrive
46	ev_loop (loop, 0);	59	ev_loop (loop, 0);
47		60
		61	// unloop was called, so exit
48	return 0;	62	return 0;
49	}	63	}
50		64
51	=head1 DESCRIPTION	65	=head1 DESCRIPTION
52		66
53	The newest version of this document is also available as a html-formatted	67	The newest version of this document is also available as an html-formatted
54	web page you might find easier to navigate when reading it for the first	68	web page you might find easier to navigate when reading it for the first
55	time: L<http://cvs.schmorp.de/libev/ev.html>.	69	time: L<http://cvs.schmorp.de/libev/ev.html>.
56		70
57	Libev is an event loop: you register interest in certain events (such as a	71	Libev is an event loop: you register interest in certain events (such as a
58	file descriptor being readable or a timeout occurring), and it will manage	72	file descriptor being readable or a timeout occurring), and it will manage
…		…
84	L<benchmark\|http://libev.schmorp.de/bench.html> comparing it to libevent	98	L<benchmark\|http://libev.schmorp.de/bench.html> comparing it to libevent
85	for example).	99	for example).
86		100
87	=head2 CONVENTIONS	101	=head2 CONVENTIONS
88		102
89	Libev is very configurable. In this manual the default configuration will	103	Libev is very configurable. In this manual the default (and most common)
90	be described, which supports multiple event loops. For more info about	104	configuration will be described, which supports multiple event loops. For
91	various configuration options please have a look at B<EMBED> section in	105	more info about various configuration options please have a look at
92	this manual. If libev was configured without support for multiple event	106	B<EMBED> section in this manual. If libev was configured without support
93	loops, then all functions taking an initial argument of name C<loop>	107	for multiple event loops, then all functions taking an initial argument of
94	(which is always of type C<struct ev_loop *>) will not have this argument.	108	name C<loop> (which is always of type C<struct ev_loop *>) will not have
		109	this argument.
95		110
96	=head2 TIME REPRESENTATION	111	=head2 TIME REPRESENTATION
97		112
98	Libev represents time as a single floating point number, representing the	113	Libev represents time as a single floating point number, representing the
99	(fractional) number of seconds since the (POSIX) epoch (somewhere near	114	(fractional) number of seconds since the (POSIX) epoch (somewhere near
…		…
181	See the description of C<ev_embed> watchers for more info.	196	See the description of C<ev_embed> watchers for more info.
182		197
183	=item ev_set_allocator (void (cb)(void *ptr, long size))	198	=item ev_set_allocator (void (cb)(void *ptr, long size))
184		199
185	Sets the allocation function to use (the prototype is similar - the	200	Sets the allocation function to use (the prototype is similar - the
186	semantics is identical - to the realloc C function). It is used to	201	semantics are identical to the C<realloc> C89/SuS/POSIX function). It is
187	allocate and free memory (no surprises here). If it returns zero when	202	used to allocate and free memory (no surprises here). If it returns zero
188	memory needs to be allocated, the library might abort or take some	203	when memory needs to be allocated (C<size != 0>), the library might abort
189	potentially destructive action. The default is your system realloc	204	or take some potentially destructive action.
190	function.	205
		206	Since some systems (at least OpenBSD and Darwin) fail to implement
		207	correct C<realloc> semantics, libev will use a wrapper around the system
		208	C<realloc> and C<free> functions by default.
191		209
192	You could override this function in high-availability programs to, say,	210	You could override this function in high-availability programs to, say,
193	free some memory if it cannot allocate memory, to use a special allocator,	211	free some memory if it cannot allocate memory, to use a special allocator,
194	or even to sleep a while and retry until some memory is available.	212	or even to sleep a while and retry until some memory is available.
195		213
196	Example: Replace the libev allocator with one that waits a bit and then	214	Example: Replace the libev allocator with one that waits a bit and then
197	retries).	215	retries (example requires a standards-compliant C<realloc>).
198		216
199	static void *	217	static void *
200	persistent_realloc (void *ptr, size_t size)	218	persistent_realloc (void *ptr, size_t size)
201	{	219	{
202	for (;;)	220	for (;;)
…		…
241		259
242	An event loop is described by a C<struct ev_loop *>. The library knows two	260	An event loop is described by a C<struct ev_loop *>. The library knows two
243	types of such loops, the I<default> loop, which supports signals and child	261	types of such loops, the I<default> loop, which supports signals and child
244	events, and dynamically created loops which do not.	262	events, and dynamically created loops which do not.
245		263
246	If you use threads, a common model is to run the default event loop
247	in your main thread (or in a separate thread) and for each thread you
248	create, you also create another event loop. Libev itself does no locking
249	whatsoever, so if you mix calls to the same event loop in different
250	threads, make sure you lock (this is usually a bad idea, though, even if
251	done correctly, because it's hideous and inefficient).
252
253	=over 4	264	=over 4
254		265
255	=item struct ev_loop *ev_default_loop (unsigned int flags)	266	=item struct ev_loop *ev_default_loop (unsigned int flags)
256		267
257	This will initialise the default event loop if it hasn't been initialised	268	This will initialise the default event loop if it hasn't been initialised
…		…
259	false. If it already was initialised it simply returns it (and ignores the	270	false. If it already was initialised it simply returns it (and ignores the
260	flags. If that is troubling you, check C<ev_backend ()> afterwards).	271	flags. If that is troubling you, check C<ev_backend ()> afterwards).
261		272
262	If you don't know what event loop to use, use the one returned from this	273	If you don't know what event loop to use, use the one returned from this
263	function.	274	function.
		275
		276	Note that this function is I<not> thread-safe, so if you want to use it
		277	from multiple threads, you have to lock (note also that this is unlikely,
		278	as loops cannot bes hared easily between threads anyway).
264		279
265	The default loop is the only loop that can handle C<ev_signal> and	280	The default loop is the only loop that can handle C<ev_signal> and
266	C<ev_child> watchers, and to do this, it always registers a handler	281	C<ev_child> watchers, and to do this, it always registers a handler
267	for C<SIGCHLD>. If this is a problem for your app you can either	282	for C<SIGCHLD>. If this is a problem for your app you can either
268	create a dynamic loop with C<ev_loop_new> that doesn't do that, or you	283	create a dynamic loop with C<ev_loop_new> that doesn't do that, or you
…		…
297	enabling this flag.	312	enabling this flag.
298		313
299	This works by calling C<getpid ()> on every iteration of the loop,	314	This works by calling C<getpid ()> on every iteration of the loop,
300	and thus this might slow down your event loop if you do a lot of loop	315	and thus this might slow down your event loop if you do a lot of loop
301	iterations and little real work, but is usually not noticeable (on my	316	iterations and little real work, but is usually not noticeable (on my
302	Linux system for example, C<getpid> is actually a simple 5-insn sequence	317	GNU/Linux system for example, C<getpid> is actually a simple 5-insn sequence
303	without a syscall and thus I<very> fast, but my Linux system also has	318	without a syscall and thus I<very> fast, but my GNU/Linux system also has
304	C<pthread_atfork> which is even faster).	319	C<pthread_atfork> which is even faster).
305		320
306	The big advantage of this flag is that you can forget about fork (and	321	The big advantage of this flag is that you can forget about fork (and
307	forget about forgetting to tell libev about forking) when you use this	322	forget about forgetting to tell libev about forking) when you use this
308	flag.	323	flag.
…		…
339	For few fds, this backend is a bit little slower than poll and select,	354	For few fds, this backend is a bit little slower than poll and select,
340	but it scales phenomenally better. While poll and select usually scale	355	but it scales phenomenally better. While poll and select usually scale
341	like O(total_fds) where n is the total number of fds (or the highest fd),	356	like O(total_fds) where n is the total number of fds (or the highest fd),
342	epoll scales either O(1) or O(active_fds). The epoll design has a number	357	epoll scales either O(1) or O(active_fds). The epoll design has a number
343	of shortcomings, such as silently dropping events in some hard-to-detect	358	of shortcomings, such as silently dropping events in some hard-to-detect
344	cases and rewiring a syscall per fd change, no fork support and bad	359	cases and requiring a syscall per fd change, no fork support and bad
345	support for dup.	360	support for dup.
346		361
347	While stopping, setting and starting an I/O watcher in the same iteration	362	While stopping, setting and starting an I/O watcher in the same iteration
348	will result in some caching, there is still a syscall per such incident	363	will result in some caching, there is still a syscall per such incident
349	(because the fd could point to a different file description now), so its	364	(because the fd could point to a different file description now), so its
…		…
450		465
451	Similar to C<ev_default_loop>, but always creates a new event loop that is	466	Similar to C<ev_default_loop>, but always creates a new event loop that is
452	always distinct from the default loop. Unlike the default loop, it cannot	467	always distinct from the default loop. Unlike the default loop, it cannot
453	handle signal and child watchers, and attempts to do so will be greeted by	468	handle signal and child watchers, and attempts to do so will be greeted by
454	undefined behaviour (or a failed assertion if assertions are enabled).	469	undefined behaviour (or a failed assertion if assertions are enabled).
		470
		471	Note that this function I<is> thread-safe, and the recommended way to use
		472	libev with threads is indeed to create one loop per thread, and using the
		473	default loop in the "main" or "initial" thread.
455		474
456	Example: Try to create a event loop that uses epoll and nothing else.	475	Example: Try to create a event loop that uses epoll and nothing else.
457		476
458	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL \| EVFLAG_NOENV);	477	struct ev_loop *epoller = ev_loop_new (EVBACKEND_EPOLL \| EVFLAG_NOENV);
459	if (!epoller)	478	if (!epoller)
…		…
1070	To support fork in your programs, you either have to call	1089	To support fork in your programs, you either have to call
1071	C<ev_default_fork ()> or C<ev_loop_fork ()> after a fork in the child,	1090	C<ev_default_fork ()> or C<ev_loop_fork ()> after a fork in the child,
1072	enable C<EVFLAG_FORKCHECK>, or resort to C<EVBACKEND_SELECT> or	1091	enable C<EVFLAG_FORKCHECK>, or resort to C<EVBACKEND_SELECT> or
1073	C<EVBACKEND_POLL>.	1092	C<EVBACKEND_POLL>.
1074		1093
		1094	=head3 The special problem of SIGPIPE
		1095
		1096	While not really specific to libev, it is easy to forget about SIGPIPE:
		1097	when reading from a pipe whose other end has been closed, your program
		1098	gets send a SIGPIPE, which, by default, aborts your program. For most
		1099	programs this is sensible behaviour, for daemons, this is usually
		1100	undesirable.
		1101
		1102	So when you encounter spurious, unexplained daemon exits, make sure you
		1103	ignore SIGPIPE (and maybe make sure you log the exit status of your daemon
		1104	somewhere, as that would have given you a big clue).
		1105
1075		1106
1076	=head3 Watcher-Specific Functions	1107	=head3 Watcher-Specific Functions
1077		1108
1078	=over 4	1109	=over 4
1079		1110
…		…
1342	Simply stops and restarts the periodic watcher again. This is only useful	1373	Simply stops and restarts the periodic watcher again. This is only useful
1343	when you changed some parameters or the reschedule callback would return	1374	when you changed some parameters or the reschedule callback would return
1344	a different time than the last time it was called (e.g. in a crond like	1375	a different time than the last time it was called (e.g. in a crond like
1345	program when the crontabs have changed).	1376	program when the crontabs have changed).
1346		1377
		1378	=item ev_tstamp ev_periodic_at (ev_periodic *)
		1379
		1380	When active, returns the absolute time that the watcher is supposed to
		1381	trigger next.
		1382
1347	=item ev_tstamp offset [read-write]	1383	=item ev_tstamp offset [read-write]
1348		1384
1349	When repeating, this contains the offset value, otherwise this is the	1385	When repeating, this contains the offset value, otherwise this is the
1350	absolute point in time (the C<at> value passed to C<ev_periodic_set>).	1386	absolute point in time (the C<at> value passed to C<ev_periodic_set>).
1351		1387
…		…
1361	=item ev_tstamp (reschedule_cb)(struct ev_periodic w, ev_tstamp now) [read-write]	1397	=item ev_tstamp (reschedule_cb)(struct ev_periodic w, ev_tstamp now) [read-write]
1362		1398
1363	The current reschedule callback, or C<0>, if this functionality is	1399	The current reschedule callback, or C<0>, if this functionality is
1364	switched off. Can be changed any time, but changes only take effect when	1400	switched off. Can be changed any time, but changes only take effect when
1365	the periodic timer fires or C<ev_periodic_again> is being called.	1401	the periodic timer fires or C<ev_periodic_again> is being called.
1366
1367	=item ev_tstamp at [read-only]
1368
1369	When active, contains the absolute time that the watcher is supposed to
1370	trigger next.
1371		1402
1372	=back	1403	=back
1373		1404
1374	=head3 Examples	1405	=head3 Examples
1375		1406
…		…
1419	with the kernel (thus it coexists with your own signal handlers as long	1450	with the kernel (thus it coexists with your own signal handlers as long
1420	as you don't register any with libev). Similarly, when the last signal	1451	as you don't register any with libev). Similarly, when the last signal
1421	watcher for a signal is stopped libev will reset the signal handler to	1452	watcher for a signal is stopped libev will reset the signal handler to
1422	SIG_DFL (regardless of what it was set to before).	1453	SIG_DFL (regardless of what it was set to before).
1423		1454
		1455	If possible and supported, libev will install its handlers with
		1456	C<SA_RESTART> behaviour enabled, so syscalls should not be unduly
		1457	interrupted. If you have a problem with syscalls getting interrupted by
		1458	signals you can block all signals in an C<ev_check> watcher and unblock
		1459	them in an C<ev_prepare> watcher.
		1460
1424	=head3 Watcher-Specific Functions and Data Members	1461	=head3 Watcher-Specific Functions and Data Members
1425		1462
1426	=over 4	1463	=over 4
1427		1464
1428	=item ev_signal_init (ev_signal *, callback, int signum)	1465	=item ev_signal_init (ev_signal *, callback, int signum)
…		…
1454		1491
1455		1492
1456	=head2 C<ev_child> - watch out for process status changes	1493	=head2 C<ev_child> - watch out for process status changes
1457		1494
1458	Child watchers trigger when your process receives a SIGCHLD in response to	1495	Child watchers trigger when your process receives a SIGCHLD in response to
1459	some child status changes (most typically when a child of yours dies).	1496	some child status changes (most typically when a child of yours dies). It
		1497	is permissible to install a child watcher I<after> the child has been
		1498	forked (which implies it might have already exited), as long as the event
		1499	loop isn't entered (or is continued from a watcher).
		1500
		1501	Only the default event loop is capable of handling signals, and therefore
		1502	you can only rgeister child watchers in the default event loop.
		1503
		1504	=head3 Process Interaction
		1505
		1506	Libev grabs C<SIGCHLD> as soon as the default event loop is
		1507	initialised. This is necessary to guarantee proper behaviour even if
		1508	the first child watcher is started after the child exits. The occurance
		1509	of C<SIGCHLD> is recorded asynchronously, but child reaping is done
		1510	synchronously as part of the event loop processing. Libev always reaps all
		1511	children, even ones not watched.
		1512
		1513	=head3 Overriding the Built-In Processing
		1514
		1515	Libev offers no special support for overriding the built-in child
		1516	processing, but if your application collides with libev's default child
		1517	handler, you can override it easily by installing your own handler for
		1518	C<SIGCHLD> after initialising the default loop, and making sure the
		1519	default loop never gets destroyed. You are encouraged, however, to use an
		1520	event-based approach to child reaping and thus use libev's support for
		1521	that, so other libev users can use C<ev_child> watchers freely.
1460		1522
1461	=head3 Watcher-Specific Functions and Data Members	1523	=head3 Watcher-Specific Functions and Data Members
1462		1524
1463	=over 4	1525	=over 4
1464		1526
…		…
1488	The process exit/trace status caused by C<rpid> (see your systems	1550	The process exit/trace status caused by C<rpid> (see your systems
1489	C<waitpid> and C<sys/wait.h> documentation for details).	1551	C<waitpid> and C<sys/wait.h> documentation for details).
1490		1552
1491	=back	1553	=back
1492		1554
		1555	=head3 Examples
		1556
		1557	Example: C<fork()> a new process and install a child handler to wait for
		1558	its completion.
		1559
		1560	ev_child cw;
		1561
		1562	static void
		1563	child_cb (EV_P_ struct ev_child *w, int revents)
		1564	{
		1565	ev_child_stop (EV_A_ w);
		1566	printf ("process %d exited with status %x\n", w->rpid, w->rstatus);
		1567	}
		1568
		1569	pid_t pid = fork ();
		1570
		1571	if (pid < 0)
		1572	// error
		1573	else if (pid == 0)
		1574	{
		1575	// the forked child executes here
		1576	exit (1);
		1577	}
		1578	else
		1579	{
		1580	ev_child_init (&cw, child_cb, pid, 0);
		1581	ev_child_start (EV_DEFAULT_ &cw);
		1582	}
		1583
1493		1584
1494	=head2 C<ev_stat> - did the file attributes just change?	1585	=head2 C<ev_stat> - did the file attributes just change?
1495		1586
1496	This watches a filesystem path for attribute changes. That is, it calls	1587	This watches a filesystem path for attribute changes. That is, it calls
1497	C<stat> regularly (or when the OS says it changed) and sees if it changed	1588	C<stat> regularly (or when the OS says it changed) and sees if it changed
…		…
1519	as even with OS-supported change notifications, this can be	1610	as even with OS-supported change notifications, this can be
1520	resource-intensive.	1611	resource-intensive.
1521		1612
1522	At the time of this writing, only the Linux inotify interface is	1613	At the time of this writing, only the Linux inotify interface is
1523	implemented (implementing kqueue support is left as an exercise for the	1614	implemented (implementing kqueue support is left as an exercise for the
		1615	reader, note, however, that the author sees no way of implementing ev_stat
1524	reader). Inotify will be used to give hints only and should not change the	1616	semantics with kqueue). Inotify will be used to give hints only and should
1525	semantics of C<ev_stat> watchers, which means that libev sometimes needs	1617	not change the semantics of C<ev_stat> watchers, which means that libev
1526	to fall back to regular polling again even with inotify, but changes are	1618	sometimes needs to fall back to regular polling again even with inotify,
1527	usually detected immediately, and if the file exists there will be no	1619	but changes are usually detected immediately, and if the file exists there
1528	polling.	1620	will be no polling.
		1621
		1622	=head3 ABI Issues (Largefile Support)
		1623
		1624	Libev by default (unless the user overrides this) uses the default
		1625	compilation environment, which means that on systems with optionally
		1626	disabled large file support, you get the 32 bit version of the stat
		1627	structure. When using the library from programs that change the ABI to
		1628	use 64 bit file offsets the programs will fail. In that case you have to
		1629	compile libev with the same flags to get binary compatibility. This is
		1630	obviously the case with any flags that change the ABI, but the problem is
		1631	most noticably with ev_stat and largefile support.
1529		1632
1530	=head3 Inotify	1633	=head3 Inotify
1531		1634
1532	When C<inotify (7)> support has been compiled into libev (generally only	1635	When C<inotify (7)> support has been compiled into libev (generally only
1533	available on Linux) and present at runtime, it will be used to speed up	1636	available on Linux) and present at runtime, it will be used to speed up
1534	change detection where possible. The inotify descriptor will be created lazily	1637	change detection where possible. The inotify descriptor will be created lazily
1535	when the first C<ev_stat> watcher is being started.	1638	when the first C<ev_stat> watcher is being started.
1536		1639
1537	Inotify presense does not change the semantics of C<ev_stat> watchers	1640	Inotify presence does not change the semantics of C<ev_stat> watchers
1538	except that changes might be detected earlier, and in some cases, to avoid	1641	except that changes might be detected earlier, and in some cases, to avoid
1539	making regular C<stat> calls. Even in the presense of inotify support	1642	making regular C<stat> calls. Even in the presence of inotify support
1540	there are many cases where libev has to resort to regular C<stat> polling.	1643	there are many cases where libev has to resort to regular C<stat> polling.
1541		1644
1542	(There is no support for kqueue, as apparently it cannot be used to	1645	(There is no support for kqueue, as apparently it cannot be used to
1543	implement this functionality, due to the requirement of having a file	1646	implement this functionality, due to the requirement of having a file
1544	descriptor open on the object at all times).	1647	descriptor open on the object at all times).
…		…
1547		1650
1548	The C<stat ()> syscall only supports full-second resolution portably, and	1651	The C<stat ()> syscall only supports full-second resolution portably, and
1549	even on systems where the resolution is higher, many filesystems still	1652	even on systems where the resolution is higher, many filesystems still
1550	only support whole seconds.	1653	only support whole seconds.
1551		1654
1552	That means that, if the time is the only thing that changes, you might	1655	That means that, if the time is the only thing that changes, you can
1553	miss updates: on the first update, C<ev_stat> detects a change and calls	1656	easily miss updates: on the first update, C<ev_stat> detects a change and
1554	your callback, which does something. When there is another update within	1657	calls your callback, which does something. When there is another update
1555	the same second, C<ev_stat> will be unable to detect it.	1658	within the same second, C<ev_stat> will be unable to detect it as the stat
		1659	data does not change.
1556		1660
1557	The solution to this is to delay acting on a change for a second (or till	1661	The solution to this is to delay acting on a change for slightly more
1558	the next second boundary), using a roughly one-second delay C<ev_timer>	1662	than second (or till slightly after the next full second boundary), using
1559	(C<ev_timer_set (w, 0., 1.01); ev_timer_again (loop, w)>). The C<.01>	1663	a roughly one-second-delay C<ev_timer> (e.g. C<ev_timer_set (w, 0., 1.02);
1560	is added to work around small timing inconsistencies of some operating	1664	ev_timer_again (loop, w)>).
1561	systems.	1665
		1666	The C<.02> offset is added to work around small timing inconsistencies
		1667	of some operating systems (where the second counter of the current time
		1668	might be be delayed. One such system is the Linux kernel, where a call to
		1669	C<gettimeofday> might return a timestamp with a full second later than
		1670	a subsequent C<time> call - if the equivalent of C<time ()> is used to
		1671	update file times then there will be a small window where the kernel uses
		1672	the previous second to update file times but libev might already execute
		1673	the timer callback).
1562		1674
1563	=head3 Watcher-Specific Functions and Data Members	1675	=head3 Watcher-Specific Functions and Data Members
1564		1676
1565	=over 4	1677	=over 4
1566		1678
…		…
1572	C<path>. The C<interval> is a hint on how quickly a change is expected to	1684	C<path>. The C<interval> is a hint on how quickly a change is expected to
1573	be detected and should normally be specified as C<0> to let libev choose	1685	be detected and should normally be specified as C<0> to let libev choose
1574	a suitable value. The memory pointed to by C<path> must point to the same	1686	a suitable value. The memory pointed to by C<path> must point to the same
1575	path for as long as the watcher is active.	1687	path for as long as the watcher is active.
1576		1688
1577	The callback will be receive C<EV_STAT> when a change was detected,	1689	The callback will receive C<EV_STAT> when a change was detected, relative
1578	relative to the attributes at the time the watcher was started (or the	1690	to the attributes at the time the watcher was started (or the last change
1579	last change was detected).	1691	was detected).
1580		1692
1581	=item ev_stat_stat (loop, ev_stat *)	1693	=item ev_stat_stat (loop, ev_stat *)
1582		1694
1583	Updates the stat buffer immediately with new values. If you change the	1695	Updates the stat buffer immediately with new values. If you change the
1584	watched path in your callback, you could call this fucntion to avoid	1696	watched path in your callback, you could call this function to avoid
1585	detecting this change (while introducing a race condition). Can also be	1697	detecting this change (while introducing a race condition if you are not
1586	useful simply to find out the new values.	1698	the only one changing the path). Can also be useful simply to find out the
		1699	new values.
1587		1700
1588	=item ev_statdata attr [read-only]	1701	=item ev_statdata attr [read-only]
1589		1702
1590	The most-recently detected attributes of the file. Although the type is of	1703	The most-recently detected attributes of the file. Although the type is
1591	C<ev_statdata>, this is usually the (or one of the) C<struct stat> types	1704	C<ev_statdata>, this is usually the (or one of the) C<struct stat> types
1592	suitable for your system. If the C<st_nlink> member is C<0>, then there	1705	suitable for your system, but you can only rely on the POSIX-standardised
		1706	members to be present. If the C<st_nlink> member is C<0>, then there was
1593	was some error while C<stat>ing the file.	1707	some error while C<stat>ing the file.
1594		1708
1595	=item ev_statdata prev [read-only]	1709	=item ev_statdata prev [read-only]
1596		1710
1597	The previous attributes of the file. The callback gets invoked whenever	1711	The previous attributes of the file. The callback gets invoked whenever
1598	C<prev> != C<attr>.	1712	C<prev> != C<attr>, or, more precisely, one or more of these members
		1713	differ: C<st_dev>, C<st_ino>, C<st_mode>, C<st_nlink>, C<st_uid>,
		1714	C<st_gid>, C<st_rdev>, C<st_size>, C<st_atime>, C<st_mtime>, C<st_ctime>.
1599		1715
1600	=item ev_tstamp interval [read-only]	1716	=item ev_tstamp interval [read-only]
1601		1717
1602	The specified interval.	1718	The specified interval.
1603		1719
…		…
1657	}	1773	}
1658		1774
1659	...	1775	...
1660	ev_stat_init (&passwd, stat_cb, "/etc/passwd", 0.);	1776	ev_stat_init (&passwd, stat_cb, "/etc/passwd", 0.);
1661	ev_stat_start (loop, &passwd);	1777	ev_stat_start (loop, &passwd);
1662	ev_timer_init (&timer, timer_cb, 0., 1.01);	1778	ev_timer_init (&timer, timer_cb, 0., 1.02);
1663		1779
1664		1780
1665	=head2 C<ev_idle> - when you've got nothing better to do...	1781	=head2 C<ev_idle> - when you've got nothing better to do...
1666		1782
1667	Idle watchers trigger events when no other events of the same or higher	1783	Idle watchers trigger events when no other events of the same or higher
…		…
1755		1871
1756	It is recommended to give C<ev_check> watchers highest (C<EV_MAXPRI>)	1872	It is recommended to give C<ev_check> watchers highest (C<EV_MAXPRI>)
1757	priority, to ensure that they are being run before any other watchers	1873	priority, to ensure that they are being run before any other watchers
1758	after the poll. Also, C<ev_check> watchers (and C<ev_prepare> watchers,	1874	after the poll. Also, C<ev_check> watchers (and C<ev_prepare> watchers,
1759	too) should not activate ("feed") events into libev. While libev fully	1875	too) should not activate ("feed") events into libev. While libev fully
1760	supports this, they will be called before other C<ev_check> watchers	1876	supports this, they might get executed before other C<ev_check> watchers
1761	did their job. As C<ev_check> watchers are often used to embed other	1877	did their job. As C<ev_check> watchers are often used to embed other
1762	(non-libev) event loops those other event loops might be in an unusable	1878	(non-libev) event loops those other event loops might be in an unusable
1763	state until their C<ev_check> watcher ran (always remind yourself to	1879	state until their C<ev_check> watcher ran (always remind yourself to
1764	coexist peacefully with others).	1880	coexist peacefully with others).
1765		1881
…		…
1780	=head3 Examples	1896	=head3 Examples
1781		1897
1782	There are a number of principal ways to embed other event loops or modules	1898	There are a number of principal ways to embed other event loops or modules
1783	into libev. Here are some ideas on how to include libadns into libev	1899	into libev. Here are some ideas on how to include libadns into libev
1784	(there is a Perl module named C<EV::ADNS> that does this, which you could	1900	(there is a Perl module named C<EV::ADNS> that does this, which you could
1785	use for an actually working example. Another Perl module named C<EV::Glib>	1901	use as a working example. Another Perl module named C<EV::Glib> embeds a
1786	embeds a Glib main context into libev, and finally, C<Glib::EV> embeds EV	1902	Glib main context into libev, and finally, C<Glib::EV> embeds EV into the
1787	into the Glib event loop).	1903	Glib event loop).
1788		1904
1789	Method 1: Add IO watchers and a timeout watcher in a prepare handler,	1905	Method 1: Add IO watchers and a timeout watcher in a prepare handler,
1790	and in a check watcher, destroy them and call into libadns. What follows	1906	and in a check watcher, destroy them and call into libadns. What follows
1791	is pseudo-code only of course. This requires you to either use a low	1907	is pseudo-code only of course. This requires you to either use a low
1792	priority for the check watcher or use C<ev_clear_pending> explicitly, as	1908	priority for the check watcher or use C<ev_clear_pending> explicitly, as
…		…
2102	{	2218	{
2103	sometype data;	2219	sometype data;
2104		2220
2105	// no locking etc.	2221	// no locking etc.
2106	queue_put (data);	2222	queue_put (data);
2107	ev_async_send (DEFAULT_ &mysig);	2223	ev_async_send (EV_DEFAULT_ &mysig);
2108	}	2224	}
2109		2225
2110	static void	2226	static void
2111	mysig_cb (EV_P_ ev_async *w, int revents)	2227	mysig_cb (EV_P_ ev_async *w, int revents)
2112	{	2228	{
…		…
2143	// only need to lock the actual queueing operation	2259	// only need to lock the actual queueing operation
2144	pthread_mutex_lock (&mymutex);	2260	pthread_mutex_lock (&mymutex);
2145	queue_put (data);	2261	queue_put (data);
2146	pthread_mutex_unlock (&mymutex);	2262	pthread_mutex_unlock (&mymutex);
2147		2263
2148	ev_async_send (DEFAULT_ &mysig);	2264	ev_async_send (EV_DEFAULT_ &mysig);
2149	}	2265	}
2150		2266
2151	static void	2267	static void
2152	mysig_cb (EV_P_ ev_async *w, int revents)	2268	mysig_cb (EV_P_ ev_async *w, int revents)
2153	{	2269	{
…		…
2181	section below on what exactly this means).	2297	section below on what exactly this means).
2182		2298
2183	This call incurs the overhead of a syscall only once per loop iteration,	2299	This call incurs the overhead of a syscall only once per loop iteration,
2184	so while the overhead might be noticable, it doesn't apply to repeated	2300	so while the overhead might be noticable, it doesn't apply to repeated
2185	calls to C<ev_async_send>.	2301	calls to C<ev_async_send>.
		2302
		2303	=item bool = ev_async_pending (ev_async *)
		2304
		2305	Returns a non-zero value when C<ev_async_send> has been called on the
		2306	watcher but the event has not yet been processed (or even noted) by the
		2307	event loop.
		2308
		2309	C<ev_async_send> sets a flag in the watcher and wakes up the loop. When
		2310	the loop iterates next and checks for the watcher to have become active,
		2311	it will reset the flag again. C<ev_async_pending> can be used to very
		2312	quickly check wether invoking the loop might be a good idea.
		2313
		2314	Not that this does I<not> check wether the watcher itself is pending, only
		2315	wether it has been requested to make this watcher pending.
2186		2316
2187	=back	2317	=back
2188		2318
2189		2319
2190	=head1 OTHER FUNCTIONS	2320	=head1 OTHER FUNCTIONS
…		…
2262		2392
2263	=item * Priorities are not currently supported. Initialising priorities	2393	=item * Priorities are not currently supported. Initialising priorities
2264	will fail and all watchers will have the same priority, even though there	2394	will fail and all watchers will have the same priority, even though there
2265	is an ev_pri field.	2395	is an ev_pri field.
2266		2396
		2397	=item * In libevent, the last base created gets the signals, in libev, the
		2398	first base created (== the default loop) gets the signals.
		2399
2267	=item * Other members are not supported.	2400	=item * Other members are not supported.
2268		2401
2269	=item * The libev emulation is I<not> ABI compatible to libevent, you need	2402	=item * The libev emulation is I<not> ABI compatible to libevent, you need
2270	to use the libev header file and library.	2403	to use the libev header file and library.
2271		2404
…		…
2434	io.start (fd, ev::READ);	2567	io.start (fd, ev::READ);
2435	}	2568	}
2436	};	2569	};
2437		2570
2438		2571
		2572	=head1 OTHER LANGUAGE BINDINGS
		2573
		2574	Libev does not offer other language bindings itself, but bindings for a
		2575	numbe rof languages exist in the form of third-party packages. If you know
		2576	any interesting language binding in addition to the ones listed here, drop
		2577	me a note.
		2578
		2579	=over 4
		2580
		2581	=item Perl
		2582
		2583	The EV module implements the full libev API and is actually used to test
		2584	libev. EV is developed together with libev. Apart from the EV core module,
		2585	there are additional modules that implement libev-compatible interfaces
		2586	to C<libadns> (C<EV::ADNS>), C<Net::SNMP> (C<Net::SNMP::EV>) and the
		2587	C<libglib> event core (C<Glib::EV> and C<EV::Glib>).
		2588
		2589	It can be found and installed via CPAN, its homepage is found at
		2590	L<http://software.schmorp.de/pkg/EV>.
		2591
		2592	=item Ruby
		2593
		2594	Tony Arcieri has written a ruby extension that offers access to a subset
		2595	of the libev API and adds filehandle abstractions, asynchronous DNS and
		2596	more on top of it. It can be found via gem servers. Its homepage is at
		2597	L<http://rev.rubyforge.org/>.
		2598
		2599	=item D
		2600
		2601	Leandro Lucarella has written a D language binding (F<ev.d>) for libev, to
		2602	be found at L<http://git.llucax.com.ar/?p=software/ev.d.git;a=summary>.
		2603
		2604	=back
		2605
		2606
2439	=head1 MACRO MAGIC	2607	=head1 MACRO MAGIC
2440		2608
2441	Libev can be compiled with a variety of options, the most fundamantal	2609	Libev can be compiled with a variety of options, the most fundamantal
2442	of which is C<EV_MULTIPLICITY>. This option determines whether (most)	2610	of which is C<EV_MULTIPLICITY>. This option determines whether (most)
2443	functions and callbacks have an initial C<struct ev_loop *> argument.	2611	functions and callbacks have an initial C<struct ev_loop *> argument.
…		…
2477		2645
2478	=item C<EV_DEFAULT>, C<EV_DEFAULT_>	2646	=item C<EV_DEFAULT>, C<EV_DEFAULT_>
2479		2647
2480	Similar to the other two macros, this gives you the value of the default	2648	Similar to the other two macros, this gives you the value of the default
2481	loop, if multiple loops are supported ("ev loop default").	2649	loop, if multiple loops are supported ("ev loop default").
		2650
		2651	=item C<EV_DEFAULT_UC>, C<EV_DEFAULT_UC_>
		2652
		2653	Usage identical to C<EV_DEFAULT> and C<EV_DEFAULT_>, but requires that the
		2654	default loop has been initialised (C<UC> == unchecked). Their behaviour
		2655	is undefined when the default loop has not been initialised by a previous
		2656	execution of C<EV_DEFAULT>, C<EV_DEFAULT_> or C<ev_default_init (...)>.
		2657
		2658	It is often prudent to use C<EV_DEFAULT> when initialising the first
		2659	watcher in a function but use C<EV_DEFAULT_UC> afterwards.
2482		2660
2483	=back	2661	=back
2484		2662
2485	Example: Declare and initialise a check watcher, utilising the above	2663	Example: Declare and initialise a check watcher, utilising the above
2486	macros so it will work regardless of whether multiple loops are supported	2664	macros so it will work regardless of whether multiple loops are supported
…		…
2582		2760
2583	libev.m4	2761	libev.m4
2584		2762
2585	=head2 PREPROCESSOR SYMBOLS/MACROS	2763	=head2 PREPROCESSOR SYMBOLS/MACROS
2586		2764
2587	Libev can be configured via a variety of preprocessor symbols you have to define	2765	Libev can be configured via a variety of preprocessor symbols you have to
2588	before including any of its files. The default is not to build for multiplicity	2766	define before including any of its files. The default in the absense of
2589	and only include the select backend.	2767	autoconf is noted for every option.
2590		2768
2591	=over 4	2769	=over 4
2592		2770
2593	=item EV_STANDALONE	2771	=item EV_STANDALONE
2594		2772
…		…
2620	=item EV_USE_NANOSLEEP	2798	=item EV_USE_NANOSLEEP
2621		2799
2622	If defined to be C<1>, libev will assume that C<nanosleep ()> is available	2800	If defined to be C<1>, libev will assume that C<nanosleep ()> is available
2623	and will use it for delays. Otherwise it will use C<select ()>.	2801	and will use it for delays. Otherwise it will use C<select ()>.
2624		2802
		2803	=item EV_USE_EVENTFD
		2804
		2805	If defined to be C<1>, then libev will assume that C<eventfd ()> is
		2806	available and will probe for kernel support at runtime. This will improve
		2807	C<ev_signal> and C<ev_async> performance and reduce resource consumption.
		2808	If undefined, it will be enabled if the headers indicate GNU/Linux + Glibc
		2809	2.7 or newer, otherwise disabled.
		2810
2625	=item EV_USE_SELECT	2811	=item EV_USE_SELECT
2626		2812
2627	If undefined or defined to be C<1>, libev will compile in support for the	2813	If undefined or defined to be C<1>, libev will compile in support for the
2628	C<select>(2) backend. No attempt at autodetection will be done: if no	2814	C<select>(2) backend. No attempt at autodetection will be done: if no
2629	other method takes over, select will be it. Otherwise the select backend	2815	other method takes over, select will be it. Otherwise the select backend
…		…
2665		2851
2666	=item EV_USE_EPOLL	2852	=item EV_USE_EPOLL
2667		2853
2668	If defined to be C<1>, libev will compile in support for the Linux	2854	If defined to be C<1>, libev will compile in support for the Linux
2669	C<epoll>(7) backend. Its availability will be detected at runtime,	2855	C<epoll>(7) backend. Its availability will be detected at runtime,
2670	otherwise another method will be used as fallback. This is the	2856	otherwise another method will be used as fallback. This is the preferred
2671	preferred backend for GNU/Linux systems.	2857	backend for GNU/Linux systems. If undefined, it will be enabled if the
		2858	headers indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled.
2672		2859
2673	=item EV_USE_KQUEUE	2860	=item EV_USE_KQUEUE
2674		2861
2675	If defined to be C<1>, libev will compile in support for the BSD style	2862	If defined to be C<1>, libev will compile in support for the BSD style
2676	C<kqueue>(2) backend. Its actual availability will be detected at runtime,	2863	C<kqueue>(2) backend. Its actual availability will be detected at runtime,
…		…
2695		2882
2696	=item EV_USE_INOTIFY	2883	=item EV_USE_INOTIFY
2697		2884
2698	If defined to be C<1>, libev will compile in support for the Linux inotify	2885	If defined to be C<1>, libev will compile in support for the Linux inotify
2699	interface to speed up C<ev_stat> watchers. Its actual availability will	2886	interface to speed up C<ev_stat> watchers. Its actual availability will
2700	be detected at runtime.	2887	be detected at runtime. If undefined, it will be enabled if the headers
		2888	indicate GNU/Linux + Glibc 2.4 or newer, otherwise disabled.
2701		2889
2702	=item EV_ATOMIC_T	2890	=item EV_ATOMIC_T
2703		2891
2704	Libev requires an integer type (suitable for storing C<0> or C<1>) whose	2892	Libev requires an integer type (suitable for storing C<0> or C<1>) whose
2705	access is atomic with respect to other threads or signal contexts. No such	2893	access is atomic with respect to other threads or signal contexts. No such
…		…
2892		3080
2893	#include "ev_cpp.h"	3081	#include "ev_cpp.h"
2894	#include "ev.c"	3082	#include "ev.c"
2895		3083
2896		3084
		3085	=head1 THREADS AND COROUTINES
		3086
		3087	=head2 THREADS
		3088
		3089	Libev itself is completely threadsafe, but it uses no locking. This
		3090	means that you can use as many loops as you want in parallel, as long as
		3091	only one thread ever calls into one libev function with the same loop
		3092	parameter.
		3093
		3094	Or put differently: calls with different loop parameters can be done in
		3095	parallel from multiple threads, calls with the same loop parameter must be
		3096	done serially (but can be done from different threads, as long as only one
		3097	thread ever is inside a call at any point in time, e.g. by using a mutex
		3098	per loop).
		3099
		3100	If you want to know which design is best for your problem, then I cannot
		3101	help you but by giving some generic advice:
		3102
		3103	=over 4
		3104
		3105	=item * most applications have a main thread: use the default libev loop
		3106	in that thread, or create a seperate thread running only the default loop.
		3107
		3108	This helps integrating other libraries or software modules that use libev
		3109	themselves and don't care/know about threading.
		3110
		3111	=item * one loop per thread is usually a good model.
		3112
		3113	Doing this is almost never wrong, sometimes a better-performance model
		3114	exists, but it is always a good start.
		3115
		3116	=item * other models exist, such as the leader/follower pattern, where one
		3117	loop is handed through multiple threads in a kind of round-robbin fashion.
		3118
		3119	Chosing a model is hard - look around, learn, know that usually you cna do
		3120	better than you currently do :-)
		3121
		3122	=item * often you need to talk to some other thread which blocks in the
		3123	event loop - C<ev_async> watchers can be used to wake them up from other
		3124	threads safely (or from signal contexts...).
		3125
		3126	=back
		3127
		3128	=head2 COROUTINES
		3129
		3130	Libev is much more accomodating to coroutines ("cooperative threads"):
		3131	libev fully supports nesting calls to it's functions from different
		3132	coroutines (e.g. you can call C<ev_loop> on the same loop from two
		3133	different coroutines and switch freely between both coroutines running the
		3134	loop, as long as you don't confuse yourself). The only exception is that
		3135	you must not do this from C<ev_periodic> reschedule callbacks.
		3136
		3137	Care has been invested into making sure that libev does not keep local
		3138	state inside C<ev_loop>, and other calls do not usually allow coroutine
		3139	switches.
		3140
		3141
2897	=head1 COMPLEXITIES	3142	=head1 COMPLEXITIES
2898		3143
2899	In this section the complexities of (many of) the algorithms used inside	3144	In this section the complexities of (many of) the algorithms used inside
2900	libev will be explained. For complexity discussions about backends see the	3145	libev will be explained. For complexity discussions about backends see the
2901	documentation for C<ev_default_init>.	3146	documentation for C<ev_default_init>.
…		…
2971	model. Libev still offers limited functionality on this platform in	3216	model. Libev still offers limited functionality on this platform in
2972	the form of the C<EVBACKEND_SELECT> backend, and only supports socket	3217	the form of the C<EVBACKEND_SELECT> backend, and only supports socket
2973	descriptors. This only applies when using Win32 natively, not when using	3218	descriptors. This only applies when using Win32 natively, not when using
2974	e.g. cygwin.	3219	e.g. cygwin.
2975		3220
		3221	Lifting these limitations would basically require the full
		3222	re-implementation of the I/O system. If you are into these kinds of
		3223	things, then note that glib does exactly that for you in a very portable
		3224	way (note also that glib is the slowest event library known to man).
		3225
2976	There is no supported compilation method available on windows except	3226	There is no supported compilation method available on windows except
2977	embedding it into other applications.	3227	embedding it into other applications.
2978		3228
2979	Due to the many, low, and arbitrary limits on the win32 platform and the	3229	Due to the many, low, and arbitrary limits on the win32 platform and
2980	abysmal performance of winsockets, using a large number of sockets is not	3230	the abysmal performance of winsockets, using a large number of sockets
2981	recommended (and not reasonable). If your program needs to use more than	3231	is not recommended (and not reasonable). If your program needs to use
2982	a hundred or so sockets, then likely it needs to use a totally different	3232	more than a hundred or so sockets, then likely it needs to use a totally
2983	implementation for windows, as libev offers the POSIX model, which cannot	3233	different implementation for windows, as libev offers the POSIX readyness
2984	be implemented efficiently on windows (microsoft monopoly games).	3234	notification model, which cannot be implemented efficiently on windows
		3235	(microsoft monopoly games).
2985		3236
2986	=over 4	3237	=over 4
2987		3238
2988	=item The winsocket select function	3239	=item The winsocket select function
2989		3240
…		…
3003	Note that winsockets handling of fd sets is O(n), so you can easily get a	3254	Note that winsockets handling of fd sets is O(n), so you can easily get a
3004	complexity in the O(n²) range when using win32.	3255	complexity in the O(n²) range when using win32.
3005		3256
3006	=item Limited number of file descriptors	3257	=item Limited number of file descriptors
3007		3258
3008	Windows has numerous arbitrary (and low) limits on things. Early versions	3259	Windows has numerous arbitrary (and low) limits on things.
3009	of winsocket's select only supported waiting for a max. of C<64> handles	3260
		3261	Early versions of winsocket's select only supported waiting for a maximum
3010	(probably owning to the fact that all windows kernels can only wait for	3262	of C<64> handles (probably owning to the fact that all windows kernels
3011	C<64> things at the same time internally; microsoft recommends spawning a	3263	can only wait for C<64> things at the same time internally; microsoft
3012	chain of threads and wait for 63 handles and the previous thread in each).	3264	recommends spawning a chain of threads and wait for 63 handles and the
		3265	previous thread in each. Great).
3013		3266
3014	Newer versions support more handles, but you need to define C<FD_SETSIZE>	3267	Newer versions support more handles, but you need to define C<FD_SETSIZE>
3015	to some high number (e.g. C<2048>) before compiling the winsocket select	3268	to some high number (e.g. C<2048>) before compiling the winsocket select
3016	call (which might be in libev or elsewhere, for example, perl does its own	3269	call (which might be in libev or elsewhere, for example, perl does its own
3017	select emulation on windows).	3270	select emulation on windows).
…		…
3029	calling select (O(n²)) will likely make this unworkable.	3282	calling select (O(n²)) will likely make this unworkable.
3030		3283
3031	=back	3284	=back
3032		3285
3033		3286
		3287	=head1 PORTABILITY REQUIREMENTS
		3288
		3289	In addition to a working ISO-C implementation, libev relies on a few
		3290	additional extensions:
		3291
		3292	=over 4
		3293
		3294	=item C<sig_atomic_t volatile> must be thread-atomic as well
		3295
		3296	The type C<sig_atomic_t volatile> (or whatever is defined as
		3297	C<EV_ATOMIC_T>) must be atomic w.r.t. accesses from different
		3298	threads. This is not part of the specification for C<sig_atomic_t>, but is
		3299	believed to be sufficiently portable.
		3300
		3301	=item C<sigprocmask> must work in a threaded environment
		3302
		3303	Libev uses C<sigprocmask> to temporarily block signals. This is not
		3304	allowed in a threaded program (C<pthread_sigmask> has to be used). Typical
		3305	pthread implementations will either allow C<sigprocmask> in the "main
		3306	thread" or will block signals process-wide, both behaviours would
		3307	be compatible with libev. Interaction between C<sigprocmask> and
		3308	C<pthread_sigmask> could complicate things, however.
		3309
		3310	The most portable way to handle signals is to block signals in all threads
		3311	except the initial one, and run the default loop in the initial thread as
		3312	well.
		3313
		3314	=item C<long> must be large enough for common memory allocation sizes
		3315
		3316	To improve portability and simplify using libev, libev uses C<long>
		3317	internally instead of C<size_t> when allocating its data structures. On
		3318	non-POSIX systems (Microsoft...) this might be unexpectedly low, but
		3319	is still at least 31 bits everywhere, which is enough for hundreds of
		3320	millions of watchers.
		3321
		3322	=item C<double> must hold a time value in seconds with enough accuracy
		3323
		3324	The type C<double> is used to represent timestamps. It is required to have
		3325	at least 51 bits of mantissa, which is good enough for at least into the
		3326	year 4000. This requirement is fulfilled by implementations implementing
		3327	IEEE 754 (basically all existing ones).
		3328
		3329	=back
		3330
		3331	If you know of other additional requirements drop me a note.
		3332
		3333
3034	=head1 AUTHOR	3334	=head1 AUTHOR
3035		3335
3036	Marc Lehmann <libev@schmorp.de>.	3336	Marc Lehmann <libev@schmorp.de>.
3037		3337

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Comparing libev/ev.pod (file contents): Revision 1.132 by root, Wed Feb 20 17:45:29 2008 UTC vs. Revision 1.150 by root, Tue May 6 23:34:16 2008 UTC

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Comparing libev/ev.pod (file contents):
Revision 1.132 by root, Wed Feb 20 17:45:29 2008 UTC vs.
Revision 1.150 by root, Tue May 6 23:34:16 2008 UTC