[ViewVC] Diff of: cvs/IO-AIO/README

Comparing IO-AIO/README (file contents):
Revision 1.28 by root, Sun Mar 30 06:31:49 2008 UTC vs.
Revision 1.51 by root, Sat Apr 7 00:50:33 2012 UTC

…		…
2	IO::AIO - Asynchronous Input/Output	2	IO::AIO - Asynchronous Input/Output
3		3
4	SYNOPSIS	4	SYNOPSIS
5	use IO::AIO;	5	use IO::AIO;
6		6
7	aio_open "/etc/passwd", O_RDONLY, 0, sub {	7	aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
8	my $fh = shift	8	my $fh = shift
9	or die "/etc/passwd: $!";	9	or die "/etc/passwd: $!";
10	...	10	...
11	};	11	};
12		12
…		…
24	$req->cancel; # cancel request if still in queue	24	$req->cancel; # cancel request if still in queue
25		25
26	my $grp = aio_group sub { print "all stats done\n" };	26	my $grp = aio_group sub { print "all stats done\n" };
27	add $grp aio_stat "..." for ...;	27	add $grp aio_stat "..." for ...;
28		28
29	# AnyEvent integration (EV, Event, Glib, Tk, urxvt, pureperl...)
30	open my $fh, "<&=" . IO::AIO::poll_fileno or die "$!";
31	my $w = AnyEvent->io (fh => $fh, poll => 'r', cb => sub { IO::AIO::poll_cb });
32
33	# EV integration
34	my $w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
35
36	# Event integration
37	Event->io (fd => IO::AIO::poll_fileno,
38	poll => 'r',
39	cb => \&IO::AIO::poll_cb);
40
41	# Glib/Gtk2 integration
42	add_watch Glib::IO IO::AIO::poll_fileno,
43	in => sub { IO::AIO::poll_cb; 1 };
44
45	# Tk integration
46	Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
47	readable => \&IO::AIO::poll_cb);
48
49	# Danga::Socket integration
50	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
51	\&IO::AIO::poll_cb);
52
53	DESCRIPTION	29	DESCRIPTION
54	This module implements asynchronous I/O using whatever means your	30	This module implements asynchronous I/O using whatever means your
55	operating system supports.	31	operating system supports. It is implemented as an interface to "libeio"
		32	(<http://software.schmorp.de/pkg/libeio.html>).
56		33
57	Asynchronous means that operations that can normally block your program	34	Asynchronous means that operations that can normally block your program
58	(e.g. reading from disk) will be done asynchronously: the operation will	35	(e.g. reading from disk) will be done asynchronously: the operation will
59	still block, but you can do something else in the meantime. This is	36	still block, but you can do something else in the meantime. This is
60	extremely useful for programs that need to stay interactive even when	37	extremely useful for programs that need to stay interactive even when
…		…
65	operations concurrently.	42	operations concurrently.
66		43
67	While most of this works on all types of file descriptors (for example	44	While most of this works on all types of file descriptors (for example
68	sockets), using these functions on file descriptors that support	45	sockets), using these functions on file descriptors that support
69	nonblocking operation (again, sockets, pipes etc.) is very inefficient.	46	nonblocking operation (again, sockets, pipes etc.) is very inefficient.
70	Use an event loop for that (such as the Event module): IO::AIO will	47	Use an event loop for that (such as the EV module): IO::AIO will
71	naturally fit into such an event loop itself.	48	naturally fit into such an event loop itself.
72		49
73	In this version, a number of threads are started that execute your	50	In this version, a number of threads are started that execute your
74	requests and signal their completion. You don't need thread support in	51	requests and signal their completion. You don't need thread support in
75	perl, and the threads created by this module will not be visible to	52	perl, and the threads created by this module will not be visible to
…		…
84	it is currently not reentrant in any way, so use appropriate locking	61	it is currently not reentrant in any way, so use appropriate locking
85	yourself, always call "poll_cb" from within the same thread, or never	62	yourself, always call "poll_cb" from within the same thread, or never
86	call "poll_cb" (or other "aio_" functions) recursively.	63	call "poll_cb" (or other "aio_" functions) recursively.
87		64
88	EXAMPLE	65	EXAMPLE
89	This is a simple example that uses the Event module and loads	66	This is a simple example that uses the EV module and loads /etc/passwd
90	/etc/passwd asynchronously:	67	asynchronously:
91		68
92	use Fcntl;	69	use Fcntl;
93	use Event;	70	use EV;
94	use IO::AIO;	71	use IO::AIO;
95		72
96	# register the IO::AIO callback with Event	73	# register the IO::AIO callback with EV
97	Event->io (fd => IO::AIO::poll_fileno,	74	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
98	poll => 'r',
99	cb => \&IO::AIO::poll_cb);
100		75
101	# queue the request to open /etc/passwd	76	# queue the request to open /etc/passwd
102	aio_open "/etc/passwd", O_RDONLY, 0, sub {	77	aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
103	my $fh = shift	78	my $fh = shift
104	or die "error while opening: $!";	79	or die "error while opening: $!";
105		80
106	# stat'ing filehandles is generally non-blocking	81	# stat'ing filehandles is generally non-blocking
107	my $size = -s $fh;	82	my $size = -s $fh;
…		…
116		91
117	# file contents now in $contents	92	# file contents now in $contents
118	print $contents;	93	print $contents;
119		94
120	# exit event loop and program	95	# exit event loop and program
121	Event::unloop;	96	EV::unloop;
122	};	97	};
123	};	98	};
124		99
125	# possibly queue up other requests, or open GUI windows,	100	# possibly queue up other requests, or open GUI windows,
126	# check for sockets etc. etc.	101	# check for sockets etc. etc.
127		102
128	# process events as long as there are some:	103	# process events as long as there are some:
129	Event::loop;	104	EV::loop;
130		105
131	REQUEST ANATOMY AND LIFETIME	106	REQUEST ANATOMY AND LIFETIME
132	Every "aio_*" function creates a request. which is a C data structure	107	Every "aio_*" function creates a request. which is a C data structure
133	not directly visible to Perl.	108	not directly visible to Perl.
134		109
…		…
170	anymore (except possibly for the Perl object, but its connection to	145	anymore (except possibly for the Perl object, but its connection to
171	the actual aio request is severed and calling its methods will	146	the actual aio request is severed and calling its methods will
172	either do nothing or result in a runtime error).	147	either do nothing or result in a runtime error).
173		148
174	FUNCTIONS	149	FUNCTIONS
175	AIO REQUEST FUNCTIONS	150	QUICK OVERVIEW
		151	This section simply lists the prototypes of the most important functions
		152	for quick reference. See the following sections for function-by-function
		153	documentation.
		154
		155	aio_wd $pathname, $callback->($wd)
		156	aio_open $pathname, $flags, $mode, $callback->($fh)
		157	aio_close $fh, $callback->($status)
		158	aio_seek $fh,$offset,$whence, $callback->($offs)
		159	aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
		160	aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
		161	aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
		162	aio_readahead $fh,$offset,$length, $callback->($retval)
		163	aio_stat $fh_or_path, $callback->($status)
		164	aio_lstat $fh, $callback->($status)
		165	aio_statvfs $fh_or_path, $callback->($statvfs)
		166	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
		167	aio_chown $fh_or_path, $uid, $gid, $callback->($status)
		168	aio_chmod $fh_or_path, $mode, $callback->($status)
		169	aio_truncate $fh_or_path, $offset, $callback->($status)
		170	aio_unlink $pathname, $callback->($status)
		171	aio_mknod $pathname, $mode, $dev, $callback->($status)
		172	aio_link $srcpath, $dstpath, $callback->($status)
		173	aio_symlink $srcpath, $dstpath, $callback->($status)
		174	aio_readlink $pathname, $callback->($link)
		175	aio_realpath $pathname, $callback->($link)
		176	aio_rename $srcpath, $dstpath, $callback->($status)
		177	aio_mkdir $pathname, $mode, $callback->($status)
		178	aio_rmdir $pathname, $callback->($status)
		179	aio_readdir $pathname, $callback->($entries)
		180	aio_readdirx $pathname, $flags, $callback->($entries, $flags)
		181	IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST
		182	IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN
		183	aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
		184	aio_load $pathname, $data, $callback->($status)
		185	aio_copy $srcpath, $dstpath, $callback->($status)
		186	aio_move $srcpath, $dstpath, $callback->($status)
		187	aio_rmtree $pathname, $callback->($status)
		188	aio_sync $callback->($status)
		189	aio_syncfs $fh, $callback->($status)
		190	aio_fsync $fh, $callback->($status)
		191	aio_fdatasync $fh, $callback->($status)
		192	aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
		193	aio_pathsync $pathname, $callback->($status)
		194	aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		195	aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		196	aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
		197	aio_mlockall $flags, $callback->($status)
		198	aio_group $callback->(...)
		199	aio_nop $callback->()
		200
		201	$prev_pri = aioreq_pri [$pri]
		202	aioreq_nice $pri_adjust
		203
		204	IO::AIO::poll_wait
		205	IO::AIO::poll_cb
		206	IO::AIO::poll
		207	IO::AIO::flush
		208	IO::AIO::max_poll_reqs $nreqs
		209	IO::AIO::max_poll_time $seconds
		210	IO::AIO::min_parallel $nthreads
		211	IO::AIO::max_parallel $nthreads
		212	IO::AIO::max_idle $nthreads
		213	IO::AIO::idle_timeout $seconds
		214	IO::AIO::max_outstanding $maxreqs
		215	IO::AIO::nreqs
		216	IO::AIO::nready
		217	IO::AIO::npending
		218
		219	IO::AIO::sendfile $ofh, $ifh, $offset, $count
		220	IO::AIO::fadvise $fh, $offset, $len, $advice
		221	IO::AIO::madvise $scalar, $offset, $length, $advice
		222	IO::AIO::mprotect $scalar, $offset, $length, $protect
		223	IO::AIO::munlock $scalar, $offset = 0, $length = undef
		224	IO::AIO::munlockall
		225
		226	API NOTES
176	All the "aio_*" calls are more or less thin wrappers around the syscall	227	All the "aio_*" calls are more or less thin wrappers around the syscall
177	with the same name (sans "aio_"). The arguments are similar or	228	with the same name (sans "aio_"). The arguments are similar or
178	identical, and they all accept an additional (and optional) $callback	229	identical, and they all accept an additional (and optional) $callback
179	argument which must be a code reference. This code reference will get	230	argument which must be a code reference. This code reference will be
180	called with the syscall return code (e.g. most syscalls return -1 on	231	called after the syscall has been executed in an asynchronous fashion.
181	error, unlike perl, which usually delivers "false") as it's sole	232	The results of the request will be passed as arguments to the callback
182	argument when the given syscall has been executed asynchronously.	233	(and, if an error occured, in $!) - for most requests the syscall return
		234	code (e.g. most syscalls return -1 on error, unlike perl, which usually
		235	delivers "false").
		236
		237	Some requests (such as "aio_readdir") pass the actual results and
		238	communicate failures by passing "undef".
183		239
184	All functions expecting a filehandle keep a copy of the filehandle	240	All functions expecting a filehandle keep a copy of the filehandle
185	internally until the request has finished.	241	internally until the request has finished.
186		242
187	All functions return request objects of type IO::AIO::REQ that allow	243	All functions return request objects of type IO::AIO::REQ that allow
188	further manipulation of those requests while they are in-flight.	244	further manipulation of those requests while they are in-flight.
189		245
190	The pathnames you pass to these routines must be absolute and encoded	246	The pathnames you pass to these routines should be absolute. The
191	as octets. The reason for the former is that at the time the request is	247	reason for this is that at the time the request is being executed, the
192	being executed, the current working directory could have changed.	248	current working directory could have changed. Alternatively, you can
193	Alternatively, you can make sure that you never change the current	249	make sure that you never change the current working directory anywhere
194	working directory anywhere in the program and then use relative paths.	250	in the program and then use relative paths. You can also take advantage
		251	of IO::AIOs working directory abstraction, that lets you specify paths
		252	relative to some previously-opened "working directory object" - see the
		253	description of the "IO::AIO::WD" class later in this document.
195		254
196	To encode pathnames as octets, either make sure you either: a) always	255	To encode pathnames as octets, either make sure you either: a) always
197	pass in filenames you got from outside (command line, readdir etc.)	256	pass in filenames you got from outside (command line, readdir etc.)
198	without tinkering, b) are ASCII or ISO 8859-1, c) use the Encode module	257	without tinkering, b) are in your native filesystem encoding, c) use the
199	and encode your pathnames to the locale (or other) encoding in effect in	258	Encode module and encode your pathnames to the locale (or other)
200	the user environment, d) use Glib::filename_from_unicode on unicode	259	encoding in effect in the user environment, d) use
201	filenames or e) use something else to ensure your scalar has the correct	260	Glib::filename_from_unicode on unicode filenames or e) use something
202	contents.	261	else to ensure your scalar has the correct contents.
203		262
204	This works, btw. independent of the internal UTF-8 bit, which IO::AIO	263	This works, btw. independent of the internal UTF-8 bit, which IO::AIO
205	handles correctly wether it is set or not.	264	handles correctly whether it is set or not.
206		265
		266	AIO REQUEST FUNCTIONS
207	$prev_pri = aioreq_pri [$pri]	267	$prev_pri = aioreq_pri [$pri]
208	Returns the priority value that would be used for the next request	268	Returns the priority value that would be used for the next request
209	and, if $pri is given, sets the priority for the next aio request.	269	and, if $pri is given, sets the priority for the next aio request.
210		270
211	The default priority is 0, the minimum and maximum priorities are -4	271	The default priority is 0, the minimum and maximum priorities are -4
…		…
250	will be modified by the umask in effect then the request is being	310	will be modified by the umask in effect then the request is being
251	executed, so better never change the umask.	311	executed, so better never change the umask.
252		312
253	Example:	313	Example:
254		314
255	aio_open "/etc/passwd", O_RDONLY, 0, sub {	315	aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
256	if ($_[0]) {	316	if ($_[0]) {
257	print "open successful, fh is $_[0]\n";	317	print "open successful, fh is $_[0]\n";
258	...	318	...
259	} else {	319	} else {
260	die "open failed: $!\n";	320	die "open failed: $!\n";
261	}	321	}
262	};	322	};
263		323
		324	In addition to all the common open modes/flags ("O_RDONLY",
		325	"O_WRONLY", "O_RDWR", "O_CREAT", "O_TRUNC", "O_EXCL" and
		326	"O_APPEND"), the following POSIX and non-POSIX constants are
		327	available (missing ones on your system are, as usual, 0):
		328
		329	"O_ASYNC", "O_DIRECT", "O_NOATIME", "O_CLOEXEC", "O_NOCTTY",
		330	"O_NOFOLLOW", "O_NONBLOCK", "O_EXEC", "O_SEARCH", "O_DIRECTORY",
		331	"O_DSYNC", "O_RSYNC", "O_SYNC" and "O_TTY_INIT".
		332
264	aio_close $fh, $callback->($status)	333	aio_close $fh, $callback->($status)
265	Asynchronously close a file and call the callback with the result	334	Asynchronously close a file and call the callback with the result
266	code.	335	code.
267		336
268	Unfortunately, you can't do this to perl. Perl insists very	337	Unfortunately, you can't do this to perl. Perl insists very
269	strongly on closing the file descriptor associated with the	338	strongly on closing the file descriptor associated with the
270	filehandle itself. Here is what aio_close will try:	339	filehandle itself.
271		340
272	1. dup()licate the fd	341	Therefore, "aio_close" will not close the filehandle - instead it
273	2. asynchronously close() the duplicated fd	342	will use dup2 to overwrite the file descriptor with the write-end of
274	3. dup()licate the fd once more	343	a pipe (the pipe fd will be created on demand and will be cached).
275	4. let perl close() the filehandle
276	5. asynchronously close the duplicated fd
277		344
278	The idea is that the first close() flushes stuff to disk that	345	Or in other words: the file descriptor will be closed, but it will
279	closing an fd will flush, so when perl closes the fd, nothing much	346	not be free for reuse until the perl filehandle is closed.
280	will need to be flushed. The second async. close() will then flush
281	stuff to disk that closing the last fd to the file will flush.
282		347
283	Just FYI, SuSv3 has this to say on close:	348	aio_seek $fh, $offset, $whence, $callback->($offs)
		349	Seeks the filehandle to the new $offset, similarly to perl's
		350	"sysseek". The $whence can use the traditional values (0 for
		351	"IO::AIO::SEEK_SET", 1 for "IO::AIO::SEEK_CUR" or 2 for
		352	"IO::AIO::SEEK_END").
284		353
285	All outstanding record locks owned by the process on the file	354	The resulting absolute offset will be passed to the callback, or -1
286	associated with the file descriptor shall be removed.	355	in case of an error.
287		356
288	If fildes refers to a socket, close() shall cause the socket to be	357	In theory, the $whence constants could be different than the
289	destroyed. ... close() shall block for up to the current linger	358	corresponding values from Fcntl, but perl guarantees they are the
290	interval until all data is transmitted.	359	same, so don't panic.
291	[this actually sounds like a specification bug, but who knows]
292
293	And at least Linux additionally actually flushes stuff on every
294	close, even when the file itself is still open.
295
296	Sounds enourmously inefficient and complicated? Yes... please show
297	me how to nuke perl's fd out of existence...
298		360
299	aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	361	aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
300	aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	362	aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
301	Reads or writes $length bytes from the specified $fh and $offset	363	Reads or writes $length bytes from or to the specified $fh and
302	into the scalar given by $data and offset $dataoffset and calls the	364	$offset into the scalar given by $data and offset $dataoffset and
303	callback without the actual number of bytes read (or -1 on error,	365	calls the callback without the actual number of bytes read (or -1 on
304	just like the syscall).	366	error, just like the syscall).
		367
		368	"aio_read" will, like "sysread", shrink or grow the $data scalar to
		369	offset plus the actual number of bytes read.
305		370
306	If $offset is undefined, then the current file descriptor offset	371	If $offset is undefined, then the current file descriptor offset
307	will be used (and updated), otherwise the file descriptor offset	372	will be used (and updated), otherwise the file descriptor offset
308	will not be changed by these calls.	373	will not be changed by these calls.
309		374
…		…
328	aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)	393	aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
329	Tries to copy $length bytes from $in_fh to $out_fh. It starts	394	Tries to copy $length bytes from $in_fh to $out_fh. It starts
330	reading at byte offset $in_offset, and starts writing at the current	395	reading at byte offset $in_offset, and starts writing at the current
331	file offset of $out_fh. Because of that, it is not safe to issue	396	file offset of $out_fh. Because of that, it is not safe to issue
332	more than one "aio_sendfile" per $out_fh, as they will interfere	397	more than one "aio_sendfile" per $out_fh, as they will interfere
333	with each other.	398	with each other. The same $in_fh works fine though, as this function
		399	does not move or use the file offset of $in_fh.
334		400
		401	Please note that "aio_sendfile" can read more bytes from $in_fh than
		402	are written, and there is no way to find out how many more bytes
		403	have been read from "aio_sendfile" alone, as "aio_sendfile" only
		404	provides the number of bytes written to $out_fh. Only if the result
		405	value equals $length one can assume that $length bytes have been
		406	read.
		407
		408	Unlike with other "aio_" functions, it makes a lot of sense to use
		409	"aio_sendfile" on non-blocking sockets, as long as one end
		410	(typically the $in_fh) is a file - the file I/O will then be
		411	asynchronous, while the socket I/O will be non-blocking. Note,
		412	however, that you can run into a trap where "aio_sendfile" reads
		413	some data with readahead, then fails to write all data, and when the
		414	socket is ready the next time, the data in the cache is already
		415	lost, forcing "aio_sendfile" to again hit the disk. Explicit
		416	"aio_read" + "aio_write" let's you better control resource usage.
		417
335	This call tries to make use of a native "sendfile" syscall to	418	This call tries to make use of a native "sendfile"-like syscall to
336	provide zero-copy operation. For this to work, $out_fh should refer	419	provide zero-copy operation. For this to work, $out_fh should refer
337	to a socket, and $in_fh should refer to mmap'able file.	420	to a socket, and $in_fh should refer to an mmap'able file.
338		421
339	If the native sendfile call fails or is not implemented, it will be	422	If a native sendfile cannot be found or it fails with "ENOSYS",
340	emulated, so you can call "aio_sendfile" on any type of filehandle	423	"EINVAL", "ENOTSUP", "EOPNOTSUPP", "EAFNOSUPPORT", "EPROTOTYPE" or
341	regardless of the limitations of the operating system.	424	"ENOTSOCK", it will be emulated, so you can call "aio_sendfile" on
		425	any type of filehandle regardless of the limitations of the
		426	operating system.
342		427
343	Please note, however, that "aio_sendfile" can read more bytes from	428	As native sendfile syscalls (as practically any non-POSIX interface
344	$in_fh than are written, and there is no way to find out how many	429	hacked together in a hurry to improve benchmark numbers) tend to be
345	bytes have been read from "aio_sendfile" alone, as "aio_sendfile"	430	rather buggy on many systems, this implementation tries to work
346	only provides the number of bytes written to $out_fh. Only if the	431	around some known bugs in Linux and FreeBSD kernels (probably
347	result value equals $length one can assume that $length bytes have	432	others, too), but that might fail, so you really really should check
348	been read.	433	the return value of "aio_sendfile" - fewre bytes than expected might
		434	have been transferred.
349		435
350	aio_readahead $fh,$offset,$length, $callback->($retval)	436	aio_readahead $fh,$offset,$length, $callback->($retval)
351	"aio_readahead" populates the page cache with data from a file so	437	"aio_readahead" populates the page cache with data from a file so
352	that subsequent reads from that file will not block on disk I/O. The	438	that subsequent reads from that file will not block on disk I/O. The
353	$offset argument specifies the starting point from which data is to	439	$offset argument specifies the starting point from which data is to
…		…
374	Currently, the stats are always 64-bit-stats, i.e. instead of	460	Currently, the stats are always 64-bit-stats, i.e. instead of
375	returning an error when stat'ing a large file, the results will be	461	returning an error when stat'ing a large file, the results will be
376	silently truncated unless perl itself is compiled with large file	462	silently truncated unless perl itself is compiled with large file
377	support.	463	support.
378		464
		465	To help interpret the mode and dev/rdev stat values, IO::AIO offers
		466	the following constants and functions (if not implemented, the
		467	constants will be 0 and the functions will either "croak" or fall
		468	back on traditional behaviour).
		469
		470	"S_IFMT", "S_IFIFO", "S_IFCHR", "S_IFBLK", "S_IFLNK", "S_IFREG",
		471	"S_IFDIR", "S_IFWHT", "S_IFSOCK", "IO::AIO::major $dev_t",
		472	"IO::AIO::minor $dev_t", "IO::AIO::makedev $major, $minor".
		473
379	Example: Print the length of /etc/passwd:	474	Example: Print the length of /etc/passwd:
380		475
381	aio_stat "/etc/passwd", sub {	476	aio_stat "/etc/passwd", sub {
382	$_[0] and die "stat failed: $!";	477	$_[0] and die "stat failed: $!";
383	print "size is ", -s _, "\n";	478	print "size is ", -s _, "\n";
384	};	479	};
385		480
		481	aio_statvfs $fh_or_path, $callback->($statvfs)
		482	Works like the POSIX "statvfs" or "fstatvfs" syscalls, depending on
		483	whether a file handle or path was passed.
		484
		485	On success, the callback is passed a hash reference with the
		486	following members: "bsize", "frsize", "blocks", "bfree", "bavail",
		487	"files", "ffree", "favail", "fsid", "flag" and "namemax". On
		488	failure, "undef" is passed.
		489
		490	The following POSIX IO::AIO::ST_* constants are defined: "ST_RDONLY"
		491	and "ST_NOSUID".
		492
		493	The following non-POSIX IO::AIO::ST_* flag masks are defined to
		494	their correct value when available, or to 0 on systems that do not
		495	support them: "ST_NODEV", "ST_NOEXEC", "ST_SYNCHRONOUS",
		496	"ST_MANDLOCK", "ST_WRITE", "ST_APPEND", "ST_IMMUTABLE",
		497	"ST_NOATIME", "ST_NODIRATIME" and "ST_RELATIME".
		498
		499	Example: stat "/wd" and dump out the data if successful.
		500
		501	aio_statvfs "/wd", sub {
		502	my $f = $_[0]
		503	or die "statvfs: $!";
		504
		505	use Data::Dumper;
		506	say Dumper $f;
		507	};
		508
		509	# result:
		510	{
		511	bsize => 1024,
		512	bfree => 4333064312,
		513	blocks => 10253828096,
		514	files => 2050765568,
		515	flag => 4096,
		516	favail => 2042092649,
		517	bavail => 4333064312,
		518	ffree => 2042092649,
		519	namemax => 255,
		520	frsize => 1024,
		521	fsid => 1810
		522	}
		523
386	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)	524	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
387	Works like perl's "utime" function (including the special case of	525	Works like perl's "utime" function (including the special case of
388	$atime and $mtime being undef). Fractional times are supported if	526	$atime and $mtime being undef). Fractional times are supported if
389	the underlying syscalls support them.	527	the underlying syscalls support them.
390		528
…		…
419		557
420	aio_unlink $pathname, $callback->($status)	558	aio_unlink $pathname, $callback->($status)
421	Asynchronously unlink (delete) a file and call the callback with the	559	Asynchronously unlink (delete) a file and call the callback with the
422	result code.	560	result code.
423		561
424	aio_mknod $path, $mode, $dev, $callback->($status)	562	aio_mknod $pathname, $mode, $dev, $callback->($status)
425	[EXPERIMENTAL]	563	[EXPERIMENTAL]
426		564
427	Asynchronously create a device node (or fifo). See mknod(2).	565	Asynchronously create a device node (or fifo). See mknod(2).
428		566
429	The only (POSIX-) portable way of calling this function is:	567	The only (POSIX-) portable way of calling this function is:
430		568
431	aio_mknod $path, IO::AIO::S_IFIFO \| $mode, 0, sub { ...	569	aio_mknod $pathname, IO::AIO::S_IFIFO \| $mode, 0, sub { ...
		570
		571	See "aio_stat" for info about some potentially helpful extra
		572	constants and functions.
432		573
433	aio_link $srcpath, $dstpath, $callback->($status)	574	aio_link $srcpath, $dstpath, $callback->($status)
434	Asynchronously create a new link to the existing object at $srcpath	575	Asynchronously create a new link to the existing object at $srcpath
435	at the path $dstpath and call the callback with the result code.	576	at the path $dstpath and call the callback with the result code.
436		577
437	aio_symlink $srcpath, $dstpath, $callback->($status)	578	aio_symlink $srcpath, $dstpath, $callback->($status)
438	Asynchronously create a new symbolic link to the existing object at	579	Asynchronously create a new symbolic link to the existing object at
439	$srcpath at the path $dstpath and call the callback with the result	580	$srcpath at the path $dstpath and call the callback with the result
440	code.	581	code.
441		582
442	aio_readlink $path, $callback->($link)	583	aio_readlink $pathname, $callback->($link)
443	Asynchronously read the symlink specified by $path and pass it to	584	Asynchronously read the symlink specified by $path and pass it to
444	the callback. If an error occurs, nothing or undef gets passed to	585	the callback. If an error occurs, nothing or undef gets passed to
445	the callback.	586	the callback.
		587
		588	aio_realpath $pathname, $callback->($path)
		589	Asynchronously make the path absolute and resolve any symlinks in
		590	$path. The resulting path only consists of directories (Same as
		591	Cwd::realpath).
		592
		593	This request can be used to get the absolute path of the current
		594	working directory by passing it a path of . (a single dot).
446		595
447	aio_rename $srcpath, $dstpath, $callback->($status)	596	aio_rename $srcpath, $dstpath, $callback->($status)
448	Asynchronously rename the object at $srcpath to $dstpath, just as	597	Asynchronously rename the object at $srcpath to $dstpath, just as
449	rename(2) and call the callback with the result code.	598	rename(2) and call the callback with the result code.
450		599
…		…
460	aio_readdir $pathname, $callback->($entries)	609	aio_readdir $pathname, $callback->($entries)
461	Unlike the POSIX call of the same name, "aio_readdir" reads an	610	Unlike the POSIX call of the same name, "aio_readdir" reads an
462	entire directory (i.e. opendir + readdir + closedir). The entries	611	entire directory (i.e. opendir + readdir + closedir). The entries
463	will not be sorted, and will NOT include the "." and ".." entries.	612	will not be sorted, and will NOT include the "." and ".." entries.
464		613
465	The callback a single argument which is either "undef" or an	614	The callback is passed a single argument which is either "undef" or
466	array-ref with the filenames.	615	an array-ref with the filenames.
467		616
		617	aio_readdirx $pathname, $flags, $callback->($entries, $flags)
		618	Quite similar to "aio_readdir", but the $flags argument allows one
		619	to tune behaviour and output format. In case of an error, $entries
		620	will be "undef".
		621
		622	The flags are a combination of the following constants, ORed
		623	together (the flags will also be passed to the callback, possibly
		624	modified):
		625
		626	IO::AIO::READDIR_DENTS
		627	When this flag is off, then the callback gets an arrayref
		628	consisting of names only (as with "aio_readdir"), otherwise it
		629	gets an arrayref with "[$name, $type, $inode]" arrayrefs, each
		630	describing a single directory entry in more detail.
		631
		632	$name is the name of the entry.
		633
		634	$type is one of the "IO::AIO::DT_xxx" constants:
		635
		636	"IO::AIO::DT_UNKNOWN", "IO::AIO::DT_FIFO", "IO::AIO::DT_CHR",
		637	"IO::AIO::DT_DIR", "IO::AIO::DT_BLK", "IO::AIO::DT_REG",
		638	"IO::AIO::DT_LNK", "IO::AIO::DT_SOCK", "IO::AIO::DT_WHT".
		639
		640	"IO::AIO::DT_UNKNOWN" means just that: readdir does not know. If
		641	you need to know, you have to run stat yourself. Also, for speed
		642	reasons, the $type scalars are read-only: you can not modify
		643	them.
		644
		645	$inode is the inode number (which might not be exact on systems
		646	with 64 bit inode numbers and 32 bit perls). This field has
		647	unspecified content on systems that do not deliver the inode
		648	information.
		649
		650	IO::AIO::READDIR_DIRS_FIRST
		651	When this flag is set, then the names will be returned in an
		652	order where likely directories come first, in optimal stat
		653	order. This is useful when you need to quickly find directories,
		654	or you want to find all directories while avoiding to stat()
		655	each entry.
		656
		657	If the system returns type information in readdir, then this is
		658	used to find directories directly. Otherwise, likely directories
		659	are names beginning with ".", or otherwise names with no dots,
		660	of which names with short names are tried first.
		661
		662	IO::AIO::READDIR_STAT_ORDER
		663	When this flag is set, then the names will be returned in an
		664	order suitable for stat()'ing each one. That is, when you plan
		665	to stat() all files in the given directory, then the returned
		666	order will likely be fastest.
		667
		668	If both this flag and "IO::AIO::READDIR_DIRS_FIRST" are
		669	specified, then the likely dirs come first, resulting in a less
		670	optimal stat order.
		671
		672	IO::AIO::READDIR_FOUND_UNKNOWN
		673	This flag should not be set when calling "aio_readdirx".
		674	Instead, it is being set by "aio_readdirx", when any of the
		675	$type's found were "IO::AIO::DT_UNKNOWN". The absence of this
		676	flag therefore indicates that all $type's are known, which can
		677	be used to speed up some algorithms.
		678
468	aio_load $path, $data, $callback->($status)	679	aio_load $pathname, $data, $callback->($status)
469	This is a composite request that tries to fully load the given file	680	This is a composite request that tries to fully load the given file
470	into memory. Status is the same as with aio_read.	681	into memory. Status is the same as with aio_read.
471		682
472	aio_copy $srcpath, $dstpath, $callback->($status)	683	aio_copy $srcpath, $dstpath, $callback->($status)
473	Try to copy the file (directories not supported as either source	684	Try to copy the file (directories not supported as either source
474	or destination) from $srcpath to $dstpath and call the callback with	685	or destination) from $srcpath to $dstpath and call the callback with
475	the 0 (error) or -1 ok.	686	a status of 0 (ok) or -1 (error, see $!).
476		687
477	This is a composite request that it creates the destination file	688	This is a composite request that creates the destination file with
478	with mode 0200 and copies the contents of the source file into it	689	mode 0200 and copies the contents of the source file into it using
479	using "aio_sendfile", followed by restoring atime, mtime, access	690	"aio_sendfile", followed by restoring atime, mtime, access mode and
480	mode and uid/gid, in that order.	691	uid/gid, in that order.
481		692
482	If an error occurs, the partial destination file will be unlinked,	693	If an error occurs, the partial destination file will be unlinked,
483	if possible, except when setting atime, mtime, access mode and	694	if possible, except when setting atime, mtime, access mode and
484	uid/gid, where errors are being ignored.	695	uid/gid, where errors are being ignored.
485		696
486	aio_move $srcpath, $dstpath, $callback->($status)	697	aio_move $srcpath, $dstpath, $callback->($status)
487	Try to move the file (directories not supported as either source	698	Try to move the file (directories not supported as either source
488	or destination) from $srcpath to $dstpath and call the callback with	699	or destination) from $srcpath to $dstpath and call the callback with
489	the 0 (error) or -1 ok.	700	a status of 0 (ok) or -1 (error, see $!).
490		701
491	This is a composite request that tries to rename(2) the file first.	702	This is a composite request that tries to rename(2) the file first;
492	If rename files with "EXDEV", it copies the file with "aio_copy"	703	if rename fails with "EXDEV", it copies the file with "aio_copy"
493	and, if that is successful, unlinking the $srcpath.	704	and, if that is successful, unlinks the $srcpath.
494		705
495	aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	706	aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
496	Scans a directory (similar to "aio_readdir") but additionally tries	707	Scans a directory (similar to "aio_readdir") but additionally tries
497	to efficiently separate the entries of directory $path into two sets	708	to efficiently separate the entries of directory $path into two sets
498	of names, directories you can recurse into (directories), and ones	709	of names, directories you can recurse into (directories), and ones
499	you cannot recurse into (everything else, including symlinks to	710	you cannot recurse into (everything else, including symlinks to
500	directories).	711	directories).
…		…
518	Implementation notes.	729	Implementation notes.
519		730
520	The "aio_readdir" cannot be avoided, but "stat()"'ing every entry	731	The "aio_readdir" cannot be avoided, but "stat()"'ing every entry
521	can.	732	can.
522		733
		734	If readdir returns file type information, then this is used directly
		735	to find directories.
		736
523	After reading the directory, the modification time, size etc. of the	737	Otherwise, after reading the directory, the modification time, size
524	directory before and after the readdir is checked, and if they match	738	etc. of the directory before and after the readdir is checked, and
525	(and isn't the current time), the link count will be used to decide	739	if they match (and isn't the current time), the link count will be
526	how many entries are directories (if >= 2). Otherwise, no knowledge	740	used to decide how many entries are directories (if >= 2).
527	of the number of subdirectories will be assumed.	741	Otherwise, no knowledge of the number of subdirectories will be
		742	assumed.
528		743
529	Then entries will be sorted into likely directories (everything	744	Then entries will be sorted into likely directories a non-initial
530	without a non-initial dot currently) and likely non-directories	745	dot currently) and likely non-directories (see "aio_readdirx"). Then
531	(everything else). Then every entry plus an appended "/." will be	746	every entry plus an appended "/." will be "stat"'ed, likely
532	"stat"'ed, likely directories first. If that succeeds, it assumes	747	directories first, in order of their inode numbers. If that
533	that the entry is a directory or a symlink to directory (which will	748	succeeds, it assumes that the entry is a directory or a symlink to
534	be checked seperately). This is often faster than stat'ing the entry	749	directory (which will be checked separately). This is often faster
535	itself because filesystems might detect the type of the entry	750	than stat'ing the entry itself because filesystems might detect the
536	without reading the inode data (e.g. ext2fs filetype feature).	751	type of the entry without reading the inode data (e.g. ext2fs
		752	filetype feature), even on systems that cannot return the filetype
		753	information on readdir.
537		754
538	If the known number of directories (link count - 2) has been	755	If the known number of directories (link count - 2) has been
539	reached, the rest of the entries is assumed to be non-directories.	756	reached, the rest of the entries is assumed to be non-directories.
540		757
541	This only works with certainty on POSIX (= UNIX) filesystems, which	758	This only works with certainty on POSIX (= UNIX) filesystems, which
…		…
543		760
544	It will also likely work on non-POSIX filesystems with reduced	761	It will also likely work on non-POSIX filesystems with reduced
545	efficiency as those tend to return 0 or 1 as link counts, which	762	efficiency as those tend to return 0 or 1 as link counts, which
546	disables the directory counting heuristic.	763	disables the directory counting heuristic.
547		764
548	aio_rmtree $path, $callback->($status)	765	aio_rmtree $pathname, $callback->($status)
549	Delete a directory tree starting (and including) $path, return the	766	Delete a directory tree starting (and including) $path, return the
550	status of the final "rmdir" only. This is a composite request that	767	status of the final "rmdir" only. This is a composite request that
551	uses "aio_scandir" to recurse into and rmdir directories, and unlink	768	uses "aio_scandir" to recurse into and rmdir directories, and unlink
552	everything else.	769	everything else.
553		770
…		…
563	callback with the fdatasync result code.	780	callback with the fdatasync result code.
564		781
565	If this call isn't available because your OS lacks it or it couldn't	782	If this call isn't available because your OS lacks it or it couldn't
566	be detected, it will be emulated by calling "fsync" instead.	783	be detected, it will be emulated by calling "fsync" instead.
567		784
		785	aio_syncfs $fh, $callback->($status)
		786	Asynchronously call the syncfs syscall to sync the filesystem
		787	associated to the given filehandle and call the callback with the
		788	syncfs result code. If syncfs is not available, calls sync(), but
		789	returns -1 and sets errno to "ENOSYS" nevertheless.
		790
		791	aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
		792	Sync the data portion of the file specified by $offset and $length
		793	to disk (but NOT the metadata), by calling the Linux-specific
		794	sync_file_range call. If sync_file_range is not available or it
		795	returns ENOSYS, then fdatasync or fsync is being substituted.
		796
		797	$flags can be a combination of
		798	"IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE",
		799	"IO::AIO::SYNC_FILE_RANGE_WRITE" and
		800	"IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER": refer to the sync_file_range
		801	manpage for details.
		802
568	aio_pathsync $path, $callback->($status)	803	aio_pathsync $pathname, $callback->($status)
569	This request tries to open, fsync and close the given path. This is	804	This request tries to open, fsync and close the given path. This is
570	a composite request intended tosync directories after directory	805	a composite request intended to sync directories after directory
571	operations (E.g. rename). This might not work on all operating	806	operations (E.g. rename). This might not work on all operating
572	systems or have any specific effect, but usually it makes sure that	807	systems or have any specific effect, but usually it makes sure that
573	directory changes get written to disc. It works for anything that	808	directory changes get written to disc. It works for anything that
574	can be opened for read-only, not just directories.	809	can be opened for read-only, not just directories.
575		810
		811	Future versions of this function might fall back to other methods
		812	when "fsync" on the directory fails (such as calling "sync").
		813
576	Passes 0 when everything went ok, and -1 on error.	814	Passes 0 when everything went ok, and -1 on error.
		815
		816	aio_msync $scalar, $offset = 0, $length = undef, flags = 0,
		817	$callback->($status)
		818	This is a rather advanced IO::AIO call, which only works on
		819	mmap(2)ed scalars (see the "IO::AIO::mmap" function, although it
		820	also works on data scalars managed by the Sys::Mmap or Mmap modules,
		821	note that the scalar must only be modified in-place while an aio
		822	operation is pending on it).
		823
		824	It calls the "msync" function of your OS, if available, with the
		825	memory area starting at $offset in the string and ending $length
		826	bytes later. If $length is negative, counts from the end, and if
		827	$length is "undef", then it goes till the end of the string. The
		828	flags can be a combination of "IO::AIO::MS_ASYNC",
		829	"IO::AIO::MS_INVALIDATE" and "IO::AIO::MS_SYNC".
		830
		831	aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0,
		832	$callback->($status)
		833	This is a rather advanced IO::AIO call, which works best on
		834	mmap(2)ed scalars.
		835
		836	It touches (reads or writes) all memory pages in the specified range
		837	inside the scalar. All caveats and parameters are the same as for
		838	"aio_msync", above, except for flags, which must be either 0 (which
		839	reads all pages and ensures they are instantiated) or
		840	"IO::AIO::MT_MODIFY", which modifies the memory page s(by reading
		841	and writing an octet from it, which dirties the page).
		842
		843	aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
		844	This is a rather advanced IO::AIO call, which works best on
		845	mmap(2)ed scalars.
		846
		847	It reads in all the pages of the underlying storage into memory (if
		848	any) and locks them, so they are not getting swapped/paged out or
		849	removed.
		850
		851	If $length is undefined, then the scalar will be locked till the
		852	end.
		853
		854	On systems that do not implement "mlock", this function returns -1
		855	and sets errno to "ENOSYS".
		856
		857	Note that the corresponding "munlock" is synchronous and is
		858	documented under "MISCELLANEOUS FUNCTIONS".
		859
		860	Example: open a file, mmap and mlock it - both will be undone when
		861	$data gets destroyed.
		862
		863	open my $fh, "<", $path or die "$path: $!";
		864	my $data;
		865	IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;
		866	aio_mlock $data; # mlock in background
		867
		868	aio_mlockall $flags, $callback->($status)
		869	Calls the "mlockall" function with the given $flags (a combination
		870	of "IO::AIO::MCL_CURRENT" and "IO::AIO::MCL_FUTURE").
		871
		872	On systems that do not implement "mlockall", this function returns
		873	-1 and sets errno to "ENOSYS".
		874
		875	Note that the corresponding "munlockall" is synchronous and is
		876	documented under "MISCELLANEOUS FUNCTIONS".
		877
		878	Example: asynchronously lock all current and future pages into
		879	memory.
		880
		881	aio_mlockall IO::AIO::MCL_FUTURE;
		882
		883	aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
		884	Queries the extents of the given file (by calling the Linux FIEMAP
		885	ioctl, see <http://cvs.schmorp.de/IO-AIO/doc/fiemap.txt> for
		886	details). If the "ioctl" is not available on your OS, then this
		887	rquiest will fail with "ENOSYS".
		888
		889	$start is the starting offset to query extents for, $length is the
		890	size of the range to query - if it is "undef", then the whole file
		891	will be queried.
		892
		893	$flags is a combination of flags ("IO::AIO::FIEMAP_FLAG_SYNC" or
		894	"IO::AIO::FIEMAP_FLAG_XATTR" - "IO::AIO::FIEMAP_FLAGS_COMPAT" is
		895	also exported), and is normally 0 or "IO::AIO::FIEMAP_FLAG_SYNC" to
		896	query the data portion.
		897
		898	$count is the maximum number of extent records to return. If it is
		899	"undef", then IO::AIO queries all extents of the file. As a very
		900	special case, if it is 0, then the callback receives the number of
		901	extents instead of the extents themselves.
		902
		903	If an error occurs, the callback receives no arguments. The special
		904	"errno" value "IO::AIO::EBADR" is available to test for flag errors.
		905
		906	Otherwise, the callback receives an array reference with extent
		907	structures. Each extent structure is an array reference itself, with
		908	the following members:
		909
		910	[$logical, $physical, $length, $flags]
		911
		912	Flags is any combination of the following flag values (typically
		913	either 0 or "IO::AIO::FIEMAP_EXTENT_LAST"):
		914
		915	"IO::AIO::FIEMAP_EXTENT_LAST", "IO::AIO::FIEMAP_EXTENT_UNKNOWN",
		916	"IO::AIO::FIEMAP_EXTENT_DELALLOC", "IO::AIO::FIEMAP_EXTENT_ENCODED",
		917	"IO::AIO::FIEMAP_EXTENT_DATA_ENCRYPTED",
		918	"IO::AIO::FIEMAP_EXTENT_NOT_ALIGNED",
		919	"IO::AIO::FIEMAP_EXTENT_DATA_INLINE",
		920	"IO::AIO::FIEMAP_EXTENT_DATA_TAIL",
		921	"IO::AIO::FIEMAP_EXTENT_UNWRITTEN", "IO::AIO::FIEMAP_EXTENT_MERGED"
		922	or "IO::AIO::FIEMAP_EXTENT_SHARED".
577		923
578	aio_group $callback->(...)	924	aio_group $callback->(...)
579	This is a very special aio request: Instead of doing something, it	925	This is a very special aio request: Instead of doing something, it
580	is a container for other aio requests, which is useful if you want	926	is a container for other aio requests, which is useful if you want
581	to bundle many requests into a single, composite, request with a	927	to bundle many requests into a single, composite, request with a
…		…
616	requests like sleep and file handle readable/writable, the overhead	962	requests like sleep and file handle readable/writable, the overhead
617	this creates is immense (it blocks a thread for a long time) so do	963	this creates is immense (it blocks a thread for a long time) so do
618	not use this function except to put your application under	964	not use this function except to put your application under
619	artificial I/O pressure.	965	artificial I/O pressure.
620		966
		967	IO::AIO::WD - multiple working directories
		968	Your process only has one current working directory, which is used by
		969	all threads. This makes it hard to use relative paths (some other
		970	component could call "chdir" at any time, and it is hard to control when
		971	the path will be used by IO::AIO).
		972
		973	One solution for this is to always use absolute paths. This usually
		974	works, but can be quite slow (the kernel has to walk the whole path on
		975	every access), and can also be a hassle to implement.
		976
		977	Newer POSIX systems have a number of functions (openat, fdopendir,
		978	futimensat and so on) that make it possible to specify working
		979	directories per operation.
		980
		981	For portability, and because the clowns who "designed", or shall I
		982	write, perpetrated this new interface were obviously half-drunk, this
		983	abstraction cannot be perfect, though.
		984
		985	IO::AIO allows you to convert directory paths into a so-called
		986	IO::AIO::WD object. This object stores the canonicalised, absolute
		987	version of the path, and on systems that allow it, also a directory file
		988	descriptor.
		989
		990	Everywhere where a pathname is accepted by IO::AIO (e.g. in "aio_stat"
		991	or "aio_unlink"), one can specify an array reference with an IO::AIO::WD
		992	object and a pathname instead (or the IO::AIO::WD object alone, which
		993	gets interpreted as "[$wd, "."]"). If the pathname is absolute, the
		994	IO::AIO::WD object is ignored, otherwise the pathname is resolved
		995	relative to that IO::AIO::WD object.
		996
		997	For example, to get a wd object for /etc and then stat passwd inside,
		998	you would write:
		999
		1000	aio_wd "/etc", sub {
		1001	my $etcdir = shift;
		1002
		1003	# although $etcdir can be undef on error, there is generally no reason
		1004	# to check for errors here, as aio_stat will fail with ENOENT
		1005	# when $etcdir is undef.
		1006
		1007	aio_stat [$etcdir, "passwd"], sub {
		1008	# yay
		1009	};
		1010	};
		1011
		1012	That "aio_wd" is a request and not a normal function shows that creating
		1013	an IO::AIO::WD object is itself a potentially blocking operation, which
		1014	is why it is done asynchronously.
		1015
		1016	To stat the directory obtained with "aio_wd" above, one could write
		1017	either of the following three request calls:
		1018
		1019	aio_lstat "/etc" , sub { ... # pathname as normal string
		1020	aio_lstat [$wd, "."], sub { ... # "." relative to $wd (i.e. $wd itself)
		1021	aio_lstat $wd , sub { ... # shorthand for the previous
		1022
		1023	As with normal pathnames, IO::AIO keeps a copy of the working directory
		1024	object and the pathname string, so you could write the following without
		1025	causing any issues due to $path getting reused:
		1026
		1027	my $path = [$wd, undef];
		1028
		1029	for my $name (qw(abc def ghi)) {
		1030	$path->[1] = $name;
		1031	aio_stat $path, sub {
		1032	# ...
		1033	};
		1034	}
		1035
		1036	There are some caveats: when directories get renamed (or deleted), the
		1037	pathname string doesn't change, so will point to the new directory (or
		1038	nowhere at all), while the directory fd, if available on the system,
		1039	will still point to the original directory. Most functions accepting a
		1040	pathname will use the directory fd on newer systems, and the string on
		1041	older systems. Some functions (such as realpath) will always rely on the
		1042	string form of the pathname.
		1043
		1044	So this fucntionality is mainly useful to get some protection against
		1045	"chdir", to easily get an absolute path out of a relative path for
		1046	future reference, and to speed up doing many operations in the same
		1047	directory (e.g. when stat'ing all files in a directory).
		1048
		1049	The following functions implement this working directory abstraction:
		1050
		1051	aio_wd $pathname, $callback->($wd)
		1052	Asynchonously canonicalise the given pathname and convert it to an
		1053	IO::AIO::WD object representing it. If possible and supported on the
		1054	system, also open a directory fd to speed up pathname resolution
		1055	relative to this working directory.
		1056
		1057	If something goes wrong, then "undef" is passwd to the callback
		1058	instead of a working directory object and $! is set appropriately.
		1059	Since passing "undef" as working directory component of a pathname
		1060	fails the request with "ENOENT", there is often no need for error
		1061	checking in the "aio_wd" callback, as future requests using the
		1062	value will fail in the expected way.
		1063
		1064	If this call isn't available because your OS lacks it or it couldn't
		1065	be detected, it will be emulated by calling "fsync" instead.
		1066
		1067	IO::AIO::CWD
		1068	This is a compiletime constant (object) that represents the process
		1069	current working directory.
		1070
		1071	Specifying this object as working directory object for a pathname is
		1072	as if the pathname would be specified directly, without a directory
		1073	object, e.g., these calls are functionally identical:
		1074
		1075	aio_stat "somefile", sub { ... };
		1076	aio_stat [IO::AIO::CWD, "somefile"], sub { ... };
		1077
621	IO::AIO::REQ CLASS	1078	IO::AIO::REQ CLASS
622	All non-aggregate "aio_*" functions return an object of this class when	1079	All non-aggregate "aio_*" functions return an object of this class when
623	called in non-void context.	1080	called in non-void context.
624		1081
625	cancel $req	1082	cancel $req
626	Cancels the request, if possible. Has the effect of skipping	1083	Cancels the request, if possible. Has the effect of skipping
627	execution when entering the execute state and skipping calling the	1084	execution when entering the execute state and skipping calling the
628	callback when entering the the result state, but will leave the	1085	callback when entering the the result state, but will leave the
629	request otherwise untouched. That means that requests that currently	1086	request otherwise untouched (with the exception of readdir). That
630	execute will not be stopped and resources held by the request will	1087	means that requests that currently execute will not be stopped and
631	not be freed prematurely.	1088	resources held by the request will not be freed prematurely.
632		1089
633	cb $req $callback->(...)	1090	cb $req $callback->(...)
634	Replace (or simply set) the callback registered to the request.	1091	Replace (or simply set) the callback registered to the request.
635		1092
636	IO::AIO::GRP CLASS	1093	IO::AIO::GRP CLASS
…		…
679	Their lifetime, simplified, looks like this: when they are empty, they	1136	Their lifetime, simplified, looks like this: when they are empty, they
680	will finish very quickly. If they contain only requests that are in the	1137	will finish very quickly. If they contain only requests that are in the
681	"done" state, they will also finish. Otherwise they will continue to	1138	"done" state, they will also finish. Otherwise they will continue to
682	exist.	1139	exist.
683		1140
684	That means after creating a group you have some time to add requests.	1141	That means after creating a group you have some time to add requests
685	And in the callbacks of those requests, you can add further requests to	1142	(precisely before the callback has been invoked, which is only done
686	the group. And only when all those requests have finished will the the	1143	within the "poll_cb"). And in the callbacks of those requests, you can
687	group itself finish.	1144	add further requests to the group. And only when all those requests have
		1145	finished will the the group itself finish.
688		1146
689	add $grp ...	1147	add $grp ...
690	$grp->add (...)	1148	$grp->add (...)
691	Add one or more requests to the group. Any type of IO::AIO::REQ can	1149	Add one or more requests to the group. Any type of IO::AIO::REQ can
692	be added, including other groups, as long as you do not create	1150	be added, including other groups, as long as you do not create
…		…
696		1154
697	$grp->cancel_subs	1155	$grp->cancel_subs
698	Cancel all subrequests and clears any feeder, but not the group	1156	Cancel all subrequests and clears any feeder, but not the group
699	request itself. Useful when you queued a lot of events but got a	1157	request itself. Useful when you queued a lot of events but got a
700	result early.	1158	result early.
		1159
		1160	The group request will finish normally (you cannot add requests to
		1161	the group).
701		1162
702	$grp->result (...)	1163	$grp->result (...)
703	Set the result value(s) that will be passed to the group callback	1164	Set the result value(s) that will be passed to the group callback
704	when all subrequests have finished and set the groups errno to the	1165	when all subrequests have finished and set the groups errno to the
705	current value of errno (just like calling "errno" without an error	1166	current value of errno (just like calling "errno" without an error
…		…
720	Sets a feeder/generator on this group: every group can have an	1181	Sets a feeder/generator on this group: every group can have an
721	attached generator that generates requests if idle. The idea behind	1182	attached generator that generates requests if idle. The idea behind
722	this is that, although you could just queue as many requests as you	1183	this is that, although you could just queue as many requests as you
723	want in a group, this might starve other requests for a potentially	1184	want in a group, this might starve other requests for a potentially
724	long time. For example, "aio_scandir" might generate hundreds of	1185	long time. For example, "aio_scandir" might generate hundreds of
725	thousands "aio_stat" requests, delaying any later requests for a	1186	thousands of "aio_stat" requests, delaying any later requests for a
726	long time.	1187	long time.
727		1188
728	To avoid this, and allow incremental generation of requests, you can	1189	To avoid this, and allow incremental generation of requests, you can
729	instead a group and set a feeder on it that generates those	1190	instead a group and set a feeder on it that generates those
730	requests. The feed callback will be called whenever there are few	1191	requests. The feed callback will be called whenever there are few
…		…
735	does not impose any limits).	1196	does not impose any limits).
736		1197
737	If the feed does not queue more requests when called, it will be	1198	If the feed does not queue more requests when called, it will be
738	automatically removed from the group.	1199	automatically removed from the group.
739		1200
740	If the feed limit is 0, it will be set to 2 automatically.	1201	If the feed limit is 0 when this method is called, it will be set to
		1202	2 automatically.
741		1203
742	Example:	1204	Example:
743		1205
744	# stat all files in @files, but only ever use four aio requests concurrently:	1206	# stat all files in @files, but only ever use four aio requests concurrently:
745		1207
…		…
756	Sets the feeder limit for the group: The feeder will be called	1218	Sets the feeder limit for the group: The feeder will be called
757	whenever the group contains less than this many requests.	1219	whenever the group contains less than this many requests.
758		1220
759	Setting the limit to 0 will pause the feeding process.	1221	Setting the limit to 0 will pause the feeding process.
760		1222
		1223	The default value for the limit is 0, but note that setting a feeder
		1224	automatically bumps it up to 2.
		1225
761	SUPPORT FUNCTIONS	1226	SUPPORT FUNCTIONS
762	EVENT PROCESSING AND EVENT LOOP INTEGRATION	1227	EVENT PROCESSING AND EVENT LOOP INTEGRATION
763	$fileno = IO::AIO::poll_fileno	1228	$fileno = IO::AIO::poll_fileno
764	Return the request result pipe file descriptor. This filehandle	1229	Return the request result pipe file descriptor. This filehandle
765	must be polled for reading by some mechanism outside this module	1230	must be polled for reading by some mechanism outside this module
766	(e.g. Event or select, see below or the SYNOPSIS). If the pipe	1231	(e.g. EV, Glib, select and so on, see below or the SYNOPSIS). If the
767	becomes readable you have to call "poll_cb" to check the results.	1232	pipe becomes readable you have to call "poll_cb" to check the
		1233	results.
768		1234
769	See "poll_cb" for an example.	1235	See "poll_cb" for an example.
770		1236
771	IO::AIO::poll_cb	1237	IO::AIO::poll_cb
772	Process some outstanding events on the result pipe. You have to call	1238	Process some outstanding events on the result pipe. You have to call
773	this regularly. Returns the number of events processed. Returns	1239	this regularly. Returns 0 if all events could be processed (or there
774	immediately when no events are outstanding. The amount of events	1240	were no events to process), or -1 if it returned earlier for
775	processed depends on the settings of "IO::AIO::max_poll_req" and	1241	whatever reason. Returns immediately when no events are outstanding.
776	"IO::AIO::max_poll_time".	1242	The amount of events processed depends on the settings of
		1243	"IO::AIO::max_poll_req" and "IO::AIO::max_poll_time".
777		1244
778	If not all requests were processed for whatever reason, the	1245	If not all requests were processed for whatever reason, the
779	filehandle will still be ready when "poll_cb" returns.	1246	filehandle will still be ready when "poll_cb" returns, so normally
		1247	you don't have to do anything special to have it called later.
		1248
		1249	Apart from calling "IO::AIO::poll_cb" when the event filehandle
		1250	becomes ready, it can be beneficial to call this function from loops
		1251	which submit a lot of requests, to make sure the results get
		1252	processed when they become available and not just when the loop is
		1253	finished and the event loop takes over again. This function returns
		1254	very fast when there are no outstanding requests.
780		1255
781	Example: Install an Event watcher that automatically calls	1256	Example: Install an Event watcher that automatically calls
782	IO::AIO::poll_cb with high priority:	1257	IO::AIO::poll_cb with high priority (more examples can be found in
		1258	the SYNOPSIS section, at the top of this document):
783		1259
784	Event->io (fd => IO::AIO::poll_fileno,	1260	Event->io (fd => IO::AIO::poll_fileno,
785	poll => 'r', async => 1,	1261	poll => 'r', async => 1,
786	cb => \&IO::AIO::poll_cb);	1262	cb => \&IO::AIO::poll_cb);
		1263
		1264	IO::AIO::poll_wait
		1265	If there are any outstanding requests and none of them in the result
		1266	phase, wait till the result filehandle becomes ready for reading
		1267	(simply does a "select" on the filehandle. This is useful if you
		1268	want to synchronously wait for some requests to finish).
		1269
		1270	See "nreqs" for an example.
		1271
		1272	IO::AIO::poll
		1273	Waits until some requests have been handled.
		1274
		1275	Returns the number of requests processed, but is otherwise strictly
		1276	equivalent to:
		1277
		1278	IO::AIO::poll_wait, IO::AIO::poll_cb
		1279
		1280	IO::AIO::flush
		1281	Wait till all outstanding AIO requests have been handled.
		1282
		1283	Strictly equivalent to:
		1284
		1285	IO::AIO::poll_wait, IO::AIO::poll_cb
		1286	while IO::AIO::nreqs;
787		1287
788	IO::AIO::max_poll_reqs $nreqs	1288	IO::AIO::max_poll_reqs $nreqs
789	IO::AIO::max_poll_time $seconds	1289	IO::AIO::max_poll_time $seconds
790	These set the maximum number of requests (default 0, meaning	1290	These set the maximum number of requests (default 0, meaning
791	infinity) that are being processed by "IO::AIO::poll_cb" in one	1291	infinity) that are being processed by "IO::AIO::poll_cb" in one
…		…
815	# use a low priority so other tasks have priority	1315	# use a low priority so other tasks have priority
816	Event->io (fd => IO::AIO::poll_fileno,	1316	Event->io (fd => IO::AIO::poll_fileno,
817	poll => 'r', nice => 1,	1317	poll => 'r', nice => 1,
818	cb => &IO::AIO::poll_cb);	1318	cb => &IO::AIO::poll_cb);
819		1319
820	IO::AIO::poll_wait
821	If there are any outstanding requests and none of them in the result
822	phase, wait till the result filehandle becomes ready for reading
823	(simply does a "select" on the filehandle. This is useful if you
824	want to synchronously wait for some requests to finish).
825
826	See "nreqs" for an example.
827
828	IO::AIO::poll
829	Waits until some requests have been handled.
830
831	Returns the number of requests processed, but is otherwise strictly
832	equivalent to:
833
834	IO::AIO::poll_wait, IO::AIO::poll_cb
835
836	IO::AIO::flush
837	Wait till all outstanding AIO requests have been handled.
838
839	Strictly equivalent to:
840
841	IO::AIO::poll_wait, IO::AIO::poll_cb
842	while IO::AIO::nreqs;
843
844	CONTROLLING THE NUMBER OF THREADS	1320	CONTROLLING THE NUMBER OF THREADS
845	IO::AIO::min_parallel $nthreads	1321	IO::AIO::min_parallel $nthreads
846	Set the minimum number of AIO threads to $nthreads. The current	1322	Set the minimum number of AIO threads to $nthreads. The current
847	default is 8, which means eight asynchronous operations can execute	1323	default is 8, which means eight asynchronous operations can execute
848	concurrently at any one time (the number of outstanding requests,	1324	concurrently at any one time (the number of outstanding requests,
…		…
877		1353
878	Under normal circumstances you don't need to call this function.	1354	Under normal circumstances you don't need to call this function.
879		1355
880	IO::AIO::max_idle $nthreads	1356	IO::AIO::max_idle $nthreads
881	Limit the number of threads (default: 4) that are allowed to idle	1357	Limit the number of threads (default: 4) that are allowed to idle
882	(i.e., threads that did not get a request to process within 10	1358	(i.e., threads that did not get a request to process within the idle
883	seconds). That means if a thread becomes idle while $nthreads other	1359	timeout (default: 10 seconds). That means if a thread becomes idle
884	threads are also idle, it will free its resources and exit.	1360	while $nthreads other threads are also idle, it will free its
		1361	resources and exit.
885		1362
886	This is useful when you allow a large number of threads (e.g. 100 or	1363	This is useful when you allow a large number of threads (e.g. 100 or
887	1000) to allow for extremely high load situations, but want to free	1364	1000) to allow for extremely high load situations, but want to free
888	resources under normal circumstances (1000 threads can easily	1365	resources under normal circumstances (1000 threads can easily
889	consume 30MB of RAM).	1366	consume 30MB of RAM).
890		1367
891	The default is probably ok in most situations, especially if thread	1368	The default is probably ok in most situations, especially if thread
892	creation is fast. If thread creation is very slow on your system you	1369	creation is fast. If thread creation is very slow on your system you
893	might want to use larger values.	1370	might want to use larger values.
894		1371
		1372	IO::AIO::idle_timeout $seconds
		1373	Sets the minimum idle timeout (default 10) after which worker
		1374	threads are allowed to exit. SEe "IO::AIO::max_idle".
		1375
895	$oldmaxreqs = IO::AIO::max_outstanding $maxreqs	1376	IO::AIO::max_outstanding $maxreqs
		1377	Sets the maximum number of outstanding requests to $nreqs. If you do
		1378	queue up more than this number of requests, the next call to
		1379	"IO::AIO::poll_cb" (and other functions calling "poll_cb", such as
		1380	"IO::AIO::flush" or "IO::AIO::poll") will block until the limit is
		1381	no longer exceeded.
		1382
		1383	In other words, this setting does not enforce a queue limit, but can
		1384	be used to make poll functions block if the limit is exceeded.
		1385
896	This is a very bad function to use in interactive programs because	1386	This is a very bad function to use in interactive programs because
897	it blocks, and a bad way to reduce concurrency because it is	1387	it blocks, and a bad way to reduce concurrency because it is
898	inexact: Better use an "aio_group" together with a feed callback.	1388	inexact: Better use an "aio_group" together with a feed callback.
899		1389
900	Sets the maximum number of outstanding requests to $nreqs. If you do	1390	It's main use is in scripts without an event loop - when you want to
901	queue up more than this number of requests, the next call to the	1391	stat a lot of files, you can write somehting like this:
902	"poll_cb" (and "poll_some" and other functions calling "poll_cb")
903	function will block until the limit is no longer exceeded.
904		1392
905	The default value is very large, so there is no practical limit on	1393	IO::AIO::max_outstanding 32;
		1394
		1395	for my $path (...) {
		1396	aio_stat $path , ...;
		1397	IO::AIO::poll_cb;
		1398	}
		1399
		1400	IO::AIO::flush;
		1401
		1402	The call to "poll_cb" inside the loop will normally return
		1403	instantly, but as soon as more thna 32 reqeusts are in-flight, it
		1404	will block until some requests have been handled. This keeps the
		1405	loop from pushing a large number of "aio_stat" requests onto the
		1406	queue.
		1407
		1408	The default value for "max_outstanding" is very large, so there is
906	the number of outstanding requests.	1409	no practical limit on the number of outstanding requests.
907
908	You can still queue as many requests as you want. Therefore,
909	"max_oustsanding" is mainly useful in simple scripts (with low
910	values) or as a stop gap to shield against fatal memory overflow
911	(with large values).
912		1410
913	STATISTICAL INFORMATION	1411	STATISTICAL INFORMATION
914	IO::AIO::nreqs	1412	IO::AIO::nreqs
915	Returns the number of requests currently in the ready, execute or	1413	Returns the number of requests currently in the ready, execute or
916	pending states (i.e. for which their callback has not been invoked	1414	pending states (i.e. for which their callback has not been invoked
…		…
927		1425
928	IO::AIO::npending	1426	IO::AIO::npending
929	Returns the number of requests currently in the pending state	1427	Returns the number of requests currently in the pending state
930	(executed, but not yet processed by poll_cb).	1428	(executed, but not yet processed by poll_cb).
931		1429
		1430	MISCELLANEOUS FUNCTIONS
		1431	IO::AIO implements some functions that might be useful, but are not
		1432	asynchronous.
		1433
		1434	IO::AIO::sendfile $ofh, $ifh, $offset, $count
		1435	Calls the "eio_sendfile_sync" function, which is like
		1436	"aio_sendfile", but is blocking (this makes most sense if you know
		1437	the input data is likely cached already and the output filehandle is
		1438	set to non-blocking operations).
		1439
		1440	Returns the number of bytes copied, or -1 on error.
		1441
		1442	IO::AIO::fadvise $fh, $offset, $len, $advice
		1443	Simply calls the "posix_fadvise" function (see its manpage for
		1444	details). The following advice constants are available:
		1445	"IO::AIO::FADV_NORMAL", "IO::AIO::FADV_SEQUENTIAL",
		1446	"IO::AIO::FADV_RANDOM", "IO::AIO::FADV_NOREUSE",
		1447	"IO::AIO::FADV_WILLNEED", "IO::AIO::FADV_DONTNEED".
		1448
		1449	On systems that do not implement "posix_fadvise", this function
		1450	returns ENOSYS, otherwise the return value of "posix_fadvise".
		1451
		1452	IO::AIO::madvise $scalar, $offset, $len, $advice
		1453	Simply calls the "posix_madvise" function (see its manpage for
		1454	details). The following advice constants are available:
		1455	"IO::AIO::MADV_NORMAL", "IO::AIO::MADV_SEQUENTIAL",
		1456	"IO::AIO::MADV_RANDOM", "IO::AIO::MADV_WILLNEED",
		1457	"IO::AIO::MADV_DONTNEED".
		1458
		1459	On systems that do not implement "posix_madvise", this function
		1460	returns ENOSYS, otherwise the return value of "posix_madvise".
		1461
		1462	IO::AIO::mprotect $scalar, $offset, $len, $protect
		1463	Simply calls the "mprotect" function on the preferably AIO::mmap'ed
		1464	$scalar (see its manpage for details). The following protect
		1465	constants are available: "IO::AIO::PROT_NONE", "IO::AIO::PROT_READ",
		1466	"IO::AIO::PROT_WRITE", "IO::AIO::PROT_EXEC".
		1467
		1468	On systems that do not implement "mprotect", this function returns
		1469	ENOSYS, otherwise the return value of "mprotect".
		1470
		1471	IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
		1472	Memory-maps a file (or anonymous memory range) and attaches it to
		1473	the given $scalar, which will act like a string scalar.
		1474
		1475	The only operations allowed on the scalar are "substr"/"vec" that
		1476	don't change the string length, and most read-only operations such
		1477	as copying it or searching it with regexes and so on.
		1478
		1479	Anything else is unsafe and will, at best, result in memory leaks.
		1480
		1481	The memory map associated with the $scalar is automatically removed
		1482	when the $scalar is destroyed, or when the "IO::AIO::mmap" or
		1483	"IO::AIO::munmap" functions are called.
		1484
		1485	This calls the "mmap"(2) function internally. See your system's
		1486	manual page for details on the $length, $prot and $flags parameters.
		1487
		1488	The $length must be larger than zero and smaller than the actual
		1489	filesize.
		1490
		1491	$prot is a combination of "IO::AIO::PROT_NONE",
		1492	"IO::AIO::PROT_EXEC", "IO::AIO::PROT_READ" and/or
		1493	"IO::AIO::PROT_WRITE",
		1494
		1495	$flags can be a combination of "IO::AIO::MAP_SHARED" or
		1496	"IO::AIO::MAP_PRIVATE", or a number of system-specific flags (when
		1497	not available, the are defined as 0): "IO::AIO::MAP_ANONYMOUS"
		1498	(which is set to "MAP_ANON" if your system only provides this
		1499	constant), "IO::AIO::MAP_HUGETLB", "IO::AIO::MAP_LOCKED",
		1500	"IO::AIO::MAP_NORESERVE", "IO::AIO::MAP_POPULATE" or
		1501	"IO::AIO::MAP_NONBLOCK"
		1502
		1503	If $fh is "undef", then a file descriptor of -1 is passed.
		1504
		1505	$offset is the offset from the start of the file - it generally must
		1506	be a multiple of "IO::AIO::PAGESIZE" and defaults to 0.
		1507
		1508	Example:
		1509
		1510	use Digest::MD5;
		1511	use IO::AIO;
		1512
		1513	open my $fh, "<verybigfile"
		1514	or die "$!";
		1515
		1516	IO::AIO::mmap my $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh
		1517	or die "verybigfile: $!";
		1518
		1519	my $fast_md5 = md5 $data;
		1520
		1521	IO::AIO::munmap $scalar
		1522	Removes a previous mmap and undefines the $scalar.
		1523
		1524	IO::AIO::munlock $scalar, $offset = 0, $length = undef
		1525	Calls the "munlock" function, undoing the effects of a previous
		1526	"aio_mlock" call (see its description for details).
		1527
		1528	IO::AIO::munlockall
		1529	Calls the "munlockall" function.
		1530
		1531	On systems that do not implement "munlockall", this function returns
		1532	ENOSYS, otherwise the return value of "munlockall".
		1533
		1534	EVENT LOOP INTEGRATION
		1535	It is recommended to use AnyEvent::AIO to integrate IO::AIO
		1536	automatically into many event loops:
		1537
		1538	# AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...)
		1539	use AnyEvent::AIO;
		1540
		1541	You can also integrate IO::AIO manually into many event loops, here are
		1542	some examples of how to do this:
		1543
		1544	# EV integration
		1545	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
		1546
		1547	# Event integration
		1548	Event->io (fd => IO::AIO::poll_fileno,
		1549	poll => 'r',
		1550	cb => \&IO::AIO::poll_cb);
		1551
		1552	# Glib/Gtk2 integration
		1553	add_watch Glib::IO IO::AIO::poll_fileno,
		1554	in => sub { IO::AIO::poll_cb; 1 };
		1555
		1556	# Tk integration
		1557	Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
		1558	readable => \&IO::AIO::poll_cb);
		1559
		1560	# Danga::Socket integration
		1561	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
		1562	\&IO::AIO::poll_cb);
		1563
932	FORK BEHAVIOUR	1564	FORK BEHAVIOUR
933	This module should do "the right thing" when the process using it forks:	1565	Usage of pthreads in a program changes the semantics of fork
		1566	considerably. Specifically, only async-safe functions can be called
		1567	after fork. Perl doesn't know about this, so in general, you cannot call
		1568	fork with defined behaviour in perl if pthreads are involved. IO::AIO
		1569	uses pthreads, so this applies, but many other extensions and (for
		1570	inexplicable reasons) perl itself often is linked against pthreads, so
		1571	this limitation applies to quite a lot of perls.
934		1572
935	Before the fork, IO::AIO enters a quiescent state where no requests can	1573	This module no longer tries to fight your OS, or POSIX. That means
936	be added in other threads and no results will be processed. After the	1574	IO::AIO only works in the process that loaded it. Forking is fully
937	fork the parent simply leaves the quiescent state and continues	1575	supported, but using IO::AIO in the child is not.
938	request/result processing, while the child frees the request/result
939	queue (so that the requests started before the fork will only be handled
940	in the parent). Threads will be started on demand until the limit set in
941	the parent process has been reached again.
942		1576
943	In short: the parent will, after a short pause, continue as if fork had	1577	You might get around by not using IO::AIO before (or after) forking.
944	not been called, while the child will act as if IO::AIO has not been	1578	You could also try to call the IO::AIO::reinit function in the child:
945	used yet.	1579
		1580	IO::AIO::reinit
		1581	Abandons all current requests and I/O threads and simply
		1582	reinitialises all data structures. This is not an operation
		1583	supported by any standards, but happens to work on GNU/Linux and
		1584	some newer BSD systems.
		1585
		1586	The only reasonable use for this function is to call it after
		1587	forking, if "IO::AIO" was used in the parent. Calling it while
		1588	IO::AIO is active in the process will result in undefined behaviour.
		1589	Calling it at any time will also result in any undefined (by POSIX)
		1590	behaviour.
946		1591
947	MEMORY USAGE	1592	MEMORY USAGE
948	Per-request usage:	1593	Per-request usage:
949		1594
950	Each aio request uses - depending on your architecture - around 100-200	1595	Each aio request uses - depending on your architecture - around 100-200
…		…
964		1609
965	KNOWN BUGS	1610	KNOWN BUGS
966	Known bugs will be fixed in the next release.	1611	Known bugs will be fixed in the next release.
967		1612
968	SEE ALSO	1613	SEE ALSO
969	Coro::AIO.	1614	AnyEvent::AIO for easy integration into event loops, Coro::AIO for a
		1615	more natural syntax.
970		1616
971	AUTHOR	1617	AUTHOR
972	Marc Lehmann <schmorp@schmorp.de>	1618	Marc Lehmann <schmorp@schmorp.de>
973	http://home.schmorp.de/	1619	http://home.schmorp.de/
974		1620

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Comparing IO-AIO/README (file contents): Revision 1.28 by root, Sun Mar 30 06:31:49 2008 UTC vs. Revision 1.51 by root, Sat Apr 7 00:50:33 2012 UTC

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Comparing IO-AIO/README (file contents):
Revision 1.28 by root, Sun Mar 30 06:31:49 2008 UTC vs.
Revision 1.51 by root, Sat Apr 7 00:50:33 2012 UTC