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

Comparing IO-AIO/README (file contents):
Revision 1.4 by root, Sun Jul 10 21:04:46 2005 UTC vs.
Revision 1.38 by root, Sat Jun 27 03:19:27 2009 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 {
		8	my $fh = shift
		9	or die "/etc/passwd: $!";
		10	...
		11	};
		12
		13	aio_unlink "/tmp/file", sub { };
		14
		15	aio_read $fh, 30000, 1024, $buffer, 0, sub {
		16	$_[0] > 0 or die "read error: $!";
		17	};
		18
		19	# version 2+ has request and group objects
		20	use IO::AIO 2;
		21
		22	aioreq_pri 4; # give next request a very high priority
		23	my $req = aio_unlink "/tmp/file", sub { };
		24	$req->cancel; # cancel request if still in queue
		25
		26	my $grp = aio_group sub { print "all stats done\n" };
		27	add $grp aio_stat "..." for ...;
		28
		29	# AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...)
		30	use AnyEvent::AIO;
		31
		32	# EV integration
		33	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
		34
		35	# Event integration
		36	Event->io (fd => IO::AIO::poll_fileno,
		37	poll => 'r',
		38	cb => \&IO::AIO::poll_cb);
		39
		40	# Glib/Gtk2 integration
		41	add_watch Glib::IO IO::AIO::poll_fileno,
		42	in => sub { IO::AIO::poll_cb; 1 };
		43
		44	# Tk integration
		45	Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
		46	readable => \&IO::AIO::poll_cb);
		47
		48	# Danga::Socket integration
		49	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
		50	\&IO::AIO::poll_cb);
		51
7	DESCRIPTION	52	DESCRIPTION
8	This module implements asynchronous I/O using whatever means your	53	This module implements asynchronous I/O using whatever means your
9	operating system supports.	54	operating system supports. It is implemented as an interface to "libeio"
		55	(<http://software.schmorp.de/pkg/libeio.html>).
10		56
		57	Asynchronous means that operations that can normally block your program
		58	(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
		60	extremely useful for programs that need to stay interactive even when
		61	doing heavy I/O (GUI programs, high performance network servers etc.),
		62	but can also be used to easily do operations in parallel that are
		63	normally done sequentially, e.g. stat'ing many files, which is much
		64	faster on a RAID volume or over NFS when you do a number of stat
		65	operations concurrently.
		66
		67	While most of this works on all types of file descriptors (for example
		68	sockets), using these functions on file descriptors that support
		69	nonblocking operation (again, sockets, pipes etc.) is very inefficient.
		70	Use an event loop for that (such as the EV module): IO::AIO will
		71	naturally fit into such an event loop itself.
		72
11	Currently, a number of threads are started that execute your read/writes	73	In this version, a number of threads are started that execute your
12	and signal their completion. You don't need thread support in your libc	74	requests and signal their completion. You don't need thread support in
13	or perl, and the threads created by this module will not be visible to	75	perl, and the threads created by this module will not be visible to
14	the pthreads library. In the future, this module might make use of the	76	perl. In the future, this module might make use of the native aio
15	native aio functions available on many operating systems. However, they	77	functions available on many operating systems. However, they are often
16	are often not well-supported (Linux doesn't allow them on normal files	78	not well-supported or restricted (GNU/Linux doesn't allow them on normal
17	currently, for example), and they would only support aio_read and	79	files currently, for example), and they would only support aio_read and
18	aio_write, so the remaining functionality would have to be implemented	80	aio_write, so the remaining functionality would have to be implemented
19	using threads anyway.	81	using threads anyway.
20		82
21	Although the module will work with in the presence of other threads, it	83	Although the module will work in the presence of other (Perl-) threads,
22	is currently not reentrant, so use appropriate locking yourself.	84	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
		86	call "poll_cb" (or other "aio_" functions) recursively.
		87
		88	EXAMPLE
		89	This is a simple example that uses the EV module and loads /etc/passwd
		90	asynchronously:
		91
		92	use Fcntl;
		93	use EV;
		94	use IO::AIO;
		95
		96	# register the IO::AIO callback with EV
		97	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
		98
		99	# queue the request to open /etc/passwd
		100	aio_open "/etc/passwd", O_RDONLY, 0, sub {
		101	my $fh = shift
		102	or die "error while opening: $!";
		103
		104	# stat'ing filehandles is generally non-blocking
		105	my $size = -s $fh;
		106
		107	# queue a request to read the file
		108	my $contents;
		109	aio_read $fh, 0, $size, $contents, 0, sub {
		110	$_[0] == $size
		111	or die "short read: $!";
		112
		113	close $fh;
		114
		115	# file contents now in $contents
		116	print $contents;
		117
		118	# exit event loop and program
		119	EV::unloop;
		120	};
		121	};
		122
		123	# possibly queue up other requests, or open GUI windows,
		124	# check for sockets etc. etc.
		125
		126	# process events as long as there are some:
		127	EV::loop;
		128
		129	REQUEST ANATOMY AND LIFETIME
		130	Every "aio_*" function creates a request. which is a C data structure
		131	not directly visible to Perl.
		132
		133	If called in non-void context, every request function returns a Perl
		134	object representing the request. In void context, nothing is returned,
		135	which saves a bit of memory.
		136
		137	The perl object is a fairly standard ref-to-hash object. The hash
		138	contents are not used by IO::AIO so you are free to store anything you
		139	like in it.
		140
		141	During their existance, aio requests travel through the following
		142	states, in order:
		143
		144	ready
		145	Immediately after a request is created it is put into the ready
		146	state, waiting for a thread to execute it.
		147
		148	execute
		149	A thread has accepted the request for processing and is currently
		150	executing it (e.g. blocking in read).
		151
		152	pending
		153	The request has been executed and is waiting for result processing.
		154
		155	While request submission and execution is fully asynchronous, result
		156	processing is not and relies on the perl interpreter calling
		157	"poll_cb" (or another function with the same effect).
		158
		159	result
		160	The request results are processed synchronously by "poll_cb".
		161
		162	The "poll_cb" function will process all outstanding aio requests by
		163	calling their callbacks, freeing memory associated with them and
		164	managing any groups they are contained in.
		165
		166	done
		167	Request has reached the end of its lifetime and holds no resources
		168	anymore (except possibly for the Perl object, but its connection to
		169	the actual aio request is severed and calling its methods will
		170	either do nothing or result in a runtime error).
23		171
24	FUNCTIONS	172	FUNCTIONS
25	AIO FUNCTIONS	173	AIO REQUEST FUNCTIONS
26	All the "aio_*" calls are more or less thin wrappers around the syscall	174	All the "aio_*" calls are more or less thin wrappers around the syscall
27	with the same name (sans "aio_"). The arguments are similar or	175	with the same name (sans "aio_"). The arguments are similar or
28	identical, and they all accept an additional $callback argument which	176	identical, and they all accept an additional (and optional) $callback
29	must be a code reference. This code reference will get called with the	177	argument which must be a code reference. This code reference will get
30	syscall return code (e.g. most syscalls return -1 on error, unlike perl,	178	called with the syscall return code (e.g. most syscalls return -1 on
31	which usually delivers "false") as it's sole argument when the given	179	error, unlike perl, which usually delivers "false") as its sole argument
32	syscall has been executed asynchronously.	180	after the given syscall has been executed asynchronously.
33		181
34	All functions that expect a filehandle will also accept a file	182	All functions expecting a filehandle keep a copy of the filehandle
35	descriptor.	183	internally until the request has finished.
36		184
		185	All functions return request objects of type IO::AIO::REQ that allow
		186	further manipulation of those requests while they are in-flight.
		187
37	The filenames you pass to these routines must be absolute. The reason	188	The pathnames you pass to these routines must be absolute and encoded
38	is that at the time the request is being executed, the current working	189	as octets. The reason for the former is that at the time the request is
39	directory could have changed. Alternatively, you can make sure that you	190	being executed, the current working directory could have changed.
40	never change the current working directory.	191	Alternatively, you can make sure that you never change the current
		192	working directory anywhere in the program and then use relative paths.
41		193
		194	To encode pathnames as octets, either make sure you either: a) always
		195	pass in filenames you got from outside (command line, readdir etc.)
		196	without tinkering, b) are ASCII or ISO 8859-1, c) use the Encode module
		197	and encode your pathnames to the locale (or other) encoding in effect in
		198	the user environment, d) use Glib::filename_from_unicode on unicode
		199	filenames or e) use something else to ensure your scalar has the correct
		200	contents.
		201
		202	This works, btw. independent of the internal UTF-8 bit, which IO::AIO
		203	handles correctly whether it is set or not.
		204
		205	$prev_pri = aioreq_pri [$pri]
		206	Returns the priority value that would be used for the next request
		207	and, if $pri is given, sets the priority for the next aio request.
		208
		209	The default priority is 0, the minimum and maximum priorities are -4
		210	and 4, respectively. Requests with higher priority will be serviced
		211	first.
		212
		213	The priority will be reset to 0 after each call to one of the
		214	"aio_*" functions.
		215
		216	Example: open a file with low priority, then read something from it
		217	with higher priority so the read request is serviced before other
		218	low priority open requests (potentially spamming the cache):
		219
		220	aioreq_pri -3;
		221	aio_open ..., sub {
		222	return unless $_[0];
		223
		224	aioreq_pri -2;
		225	aio_read $_[0], ..., sub {
		226	...
		227	};
		228	};
		229
		230	aioreq_nice $pri_adjust
		231	Similar to "aioreq_pri", but subtracts the given value from the
		232	current priority, so the effect is cumulative.
		233
42	aio_open $pathname, $flags, $mode, $callback	234	aio_open $pathname, $flags, $mode, $callback->($fh)
43	Asynchronously open or create a file and call the callback with a	235	Asynchronously open or create a file and call the callback with a
44	newly created filehandle for the file.	236	newly created filehandle for the file.
45		237
46	The pathname passed to "aio_open" must be absolute. See API NOTES,	238	The pathname passed to "aio_open" must be absolute. See API NOTES,
47	above, for an explanation.	239	above, for an explanation.
48		240
49	The $mode argument is a bitmask. See the "Fcntl" module for a list.	241	The $flags argument is a bitmask. See the "Fcntl" module for a list.
50	They are the same as used in "sysopen".	242	They are the same as used by "sysopen".
		243
		244	Likewise, $mode specifies the mode of the newly created file, if it
		245	didn't exist and "O_CREAT" has been given, just like perl's
		246	"sysopen", except that it is mandatory (i.e. use 0 if you don't
		247	create new files, and 0666 or 0777 if you do). Note that the $mode
		248	will be modified by the umask in effect then the request is being
		249	executed, so better never change the umask.
51		250
52	Example:	251	Example:
53		252
54	aio_open "/etc/passwd", O_RDONLY, 0, sub {	253	aio_open "/etc/passwd", O_RDONLY, 0, sub {
55	if ($_[0]) {	254	if ($_[0]) {
…		…
58	} else {	257	} else {
59	die "open failed: $!\n";	258	die "open failed: $!\n";
60	}	259	}
61	};	260	};
62		261
63	aio_close $fh, $callback	262	aio_close $fh, $callback->($status)
64	Asynchronously close a file and call the callback with the result	263	Asynchronously close a file and call the callback with the result
65	code. WARNING: although accepted, you should not pass in a perl	264	code.
66	filehandle here, as perl will likely close the file descriptor
67	itself when the filehandle is destroyed. Normally, you can safely
68	call perls "close" or just let filehandles go out of scope.
69		265
		266	Unfortunately, you can't do this to perl. Perl insists very
		267	strongly on closing the file descriptor associated with the
		268	filehandle itself.
		269
		270	Therefore, "aio_close" will not close the filehandle - instead it
		271	will use dup2 to overwrite the file descriptor with the write-end of
		272	a pipe (the pipe fd will be created on demand and will be cached).
		273
		274	Or in other words: the file descriptor will be closed, but it will
		275	not be free for reuse until the perl filehandle is closed.
		276
70	aio_read $fh,$offset,$length, $data,$dataoffset,$callback	277	aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
71	aio_write $fh,$offset,$length, $data,$dataoffset,$callback	278	aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
72	Reads or writes "length" bytes from the specified "fh" and "offset"	279	Reads or writes $length bytes from or to the specified $fh and
73	into the scalar given by "data" and offset "dataoffset" and calls	280	$offset into the scalar given by $data and offset $dataoffset and
74	the callback without the actual number of bytes read (or -1 on	281	calls the callback without the actual number of bytes read (or -1 on
75	error, just like the syscall).	282	error, just like the syscall).
76		283
		284	"aio_read" will, like "sysread", shrink or grow the $data scalar to
		285	offset plus the actual number of bytes read.
		286
		287	If $offset is undefined, then the current file descriptor offset
		288	will be used (and updated), otherwise the file descriptor offset
		289	will not be changed by these calls.
		290
		291	If $length is undefined in "aio_write", use the remaining length of
		292	$data.
		293
		294	If $dataoffset is less than zero, it will be counted from the end of
		295	$data.
		296
		297	The $data scalar MUST NOT be modified in any way while the request
		298	is outstanding. Modifying it can result in segfaults or World War
		299	III (if the necessary/optional hardware is installed).
		300
77	Example: Read 15 bytes at offset 7 into scalar $buffer, strating at	301	Example: Read 15 bytes at offset 7 into scalar $buffer, starting at
78	offset 0 within the scalar:	302	offset 0 within the scalar:
79		303
80	aio_read $fh, 7, 15, $buffer, 0, sub {	304	aio_read $fh, 7, 15, $buffer, 0, sub {
81	$_[0] >= 0 or die "read error: $!";	305	$_[0] > 0 or die "read error: $!";
82	print "read <$buffer>\n";	306	print "read $_[0] bytes: <$buffer>\n";
83	};	307	};
84		308
		309	aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
		310	Tries to copy $length bytes from $in_fh to $out_fh. It starts
		311	reading at byte offset $in_offset, and starts writing at the current
		312	file offset of $out_fh. Because of that, it is not safe to issue
		313	more than one "aio_sendfile" per $out_fh, as they will interfere
		314	with each other.
		315
		316	This call tries to make use of a native "sendfile" syscall to
		317	provide zero-copy operation. For this to work, $out_fh should refer
		318	to a socket, and $in_fh should refer to mmap'able file.
		319
		320	If the native sendfile call fails or is not implemented, it will be
		321	emulated, so you can call "aio_sendfile" on any type of filehandle
		322	regardless of the limitations of the operating system.
		323
		324	Please note, however, that "aio_sendfile" can read more bytes from
		325	$in_fh than are written, and there is no way to find out how many
		326	bytes have been read from "aio_sendfile" alone, as "aio_sendfile"
		327	only provides the number of bytes written to $out_fh. Only if the
		328	result value equals $length one can assume that $length bytes have
		329	been read.
		330
85	aio_readahead $fh,$offset,$length, $callback	331	aio_readahead $fh,$offset,$length, $callback->($retval)
86	Asynchronously reads the specified byte range into the page cache,
87	using the "readahead" syscall. If that syscall doesn't exist the
88	status will be -1 and $! is set to ENOSYS.
89
90	readahead() populates the page cache with data from a file so that	332	"aio_readahead" populates the page cache with data from a file so
91	subsequent reads from that file will not block on disk I/O. The	333	that subsequent reads from that file will not block on disk I/O. The
92	$offset argument specifies the starting point from which data is to	334	$offset argument specifies the starting point from which data is to
93	be read and $length specifies the number of bytes to be read. I/O is	335	be read and $length specifies the number of bytes to be read. I/O is
94	performed in whole pages, so that offset is effectively rounded down	336	performed in whole pages, so that offset is effectively rounded down
95	to a page boundary and bytes are read up to the next page boundary	337	to a page boundary and bytes are read up to the next page boundary
96	greater than or equal to (off-set+length). aio_readahead() does not	338	greater than or equal to (off-set+length). "aio_readahead" does not
97	read beyond the end of the file. The current file offset of the file	339	read beyond the end of the file. The current file offset of the file
98	is left unchanged.	340	is left unchanged.
99		341
		342	If that syscall doesn't exist (likely if your OS isn't Linux) it
		343	will be emulated by simply reading the data, which would have a
		344	similar effect.
		345
100	aio_stat $fh_or_path, $callback	346	aio_stat $fh_or_path, $callback->($status)
101	aio_lstat $fh, $callback	347	aio_lstat $fh, $callback->($status)
102	Works like perl's "stat" or "lstat" in void context. The callback	348	Works like perl's "stat" or "lstat" in void context. The callback
103	will be called after the stat and the results will be available	349	will be called after the stat and the results will be available
104	using "stat _" or "-s _" etc...	350	using "stat _" or "-s _" etc...
105		351
106	The pathname passed to "aio_stat" must be absolute. See API NOTES,	352	The pathname passed to "aio_stat" must be absolute. See API NOTES,
…		…
116	aio_stat "/etc/passwd", sub {	362	aio_stat "/etc/passwd", sub {
117	$_[0] and die "stat failed: $!";	363	$_[0] and die "stat failed: $!";
118	print "size is ", -s _, "\n";	364	print "size is ", -s _, "\n";
119	};	365	};
120		366
		367	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
		368	Works like perl's "utime" function (including the special case of
		369	$atime and $mtime being undef). Fractional times are supported if
		370	the underlying syscalls support them.
		371
		372	When called with a pathname, uses utimes(2) if available, otherwise
		373	utime(2). If called on a file descriptor, uses futimes(2) if
		374	available, otherwise returns ENOSYS, so this is not portable.
		375
		376	Examples:
		377
		378	# set atime and mtime to current time (basically touch(1)):
		379	aio_utime "path", undef, undef;
		380	# set atime to current time and mtime to beginning of the epoch:
		381	aio_utime "path", time, undef; # undef==0
		382
		383	aio_chown $fh_or_path, $uid, $gid, $callback->($status)
		384	Works like perl's "chown" function, except that "undef" for either
		385	$uid or $gid is being interpreted as "do not change" (but -1 can
		386	also be used).
		387
		388	Examples:
		389
		390	# same as "chown root path" in the shell:
		391	aio_chown "path", 0, -1;
		392	# same as above:
		393	aio_chown "path", 0, undef;
		394
		395	aio_truncate $fh_or_path, $offset, $callback->($status)
		396	Works like truncate(2) or ftruncate(2).
		397
		398	aio_chmod $fh_or_path, $mode, $callback->($status)
		399	Works like perl's "chmod" function.
		400
121	aio_unlink $pathname, $callback	401	aio_unlink $pathname, $callback->($status)
122	Asynchronously unlink (delete) a file and call the callback with the	402	Asynchronously unlink (delete) a file and call the callback with the
123	result code.	403	result code.
124		404
		405	aio_mknod $path, $mode, $dev, $callback->($status)
		406	[EXPERIMENTAL]
		407
		408	Asynchronously create a device node (or fifo). See mknod(2).
		409
		410	The only (POSIX-) portable way of calling this function is:
		411
		412	aio_mknod $path, IO::AIO::S_IFIFO \| $mode, 0, sub { ...
		413
		414	aio_link $srcpath, $dstpath, $callback->($status)
		415	Asynchronously create a new link to the existing object at $srcpath
		416	at the path $dstpath and call the callback with the result code.
		417
		418	aio_symlink $srcpath, $dstpath, $callback->($status)
		419	Asynchronously create a new symbolic link to the existing object at
		420	$srcpath at the path $dstpath and call the callback with the result
		421	code.
		422
		423	aio_readlink $path, $callback->($link)
		424	Asynchronously read the symlink specified by $path and pass it to
		425	the callback. If an error occurs, nothing or undef gets passed to
		426	the callback.
		427
		428	aio_rename $srcpath, $dstpath, $callback->($status)
		429	Asynchronously rename the object at $srcpath to $dstpath, just as
		430	rename(2) and call the callback with the result code.
		431
		432	aio_mkdir $pathname, $mode, $callback->($status)
		433	Asynchronously mkdir (create) a directory and call the callback with
		434	the result code. $mode will be modified by the umask at the time the
		435	request is executed, so do not change your umask.
		436
		437	aio_rmdir $pathname, $callback->($status)
		438	Asynchronously rmdir (delete) a directory and call the callback with
		439	the result code.
		440
		441	aio_readdir $pathname, $callback->($entries)
		442	Unlike the POSIX call of the same name, "aio_readdir" reads an
		443	entire directory (i.e. opendir + readdir + closedir). The entries
		444	will not be sorted, and will NOT include the "." and ".." entries.
		445
		446	The callback is passed a single argument which is either "undef" or
		447	an array-ref with the filenames.
		448
		449	aio_readdirx $pathname, $flags, $callback->($entries, $flags)
		450	Quite similar to "aio_readdir", but the $flags argument allows to
		451	tune behaviour and output format. In case of an error, $entries will
		452	be "undef".
		453
		454	The flags are a combination of the following constants, ORed
		455	together (the flags will also be passed to the callback, possibly
		456	modified):
		457
		458	IO::AIO::READDIR_DENTS
		459	When this flag is off, then the callback gets an arrayref with
		460	of names only (as with "aio_readdir"), otherwise it gets an
		461	arrayref with "[$name, $type, $inode]" arrayrefs, each
		462	describing a single directory entry in more detail.
		463
		464	$name is the name of the entry.
		465
		466	$type is one of the "IO::AIO::DT_xxx" constants:
		467
		468	"IO::AIO::DT_UNKNOWN", "IO::AIO::DT_FIFO", "IO::AIO::DT_CHR",
		469	"IO::AIO::DT_DIR", "IO::AIO::DT_BLK", "IO::AIO::DT_REG",
		470	"IO::AIO::DT_LNK", "IO::AIO::DT_SOCK", "IO::AIO::DT_WHT".
		471
		472	"IO::AIO::DT_UNKNOWN" means just that: readdir does not know. If
		473	you need to know, you have to run stat yourself. Also, for speed
		474	reasons, the $type scalars are read-only: you can not modify
		475	them.
		476
		477	$inode is the inode number (which might not be exact on systems
		478	with 64 bit inode numbers and 32 bit perls). This field has
		479	unspecified content on systems that do not deliver the inode
		480	information.
		481
		482	IO::AIO::READDIR_DIRS_FIRST
		483	When this flag is set, then the names will be returned in an
		484	order where likely directories come first. This is useful when
		485	you need to quickly find directories, or you want to find all
		486	directories while avoiding to stat() each entry.
		487
		488	If the system returns type information in readdir, then this is
		489	used to find directories directly. Otherwise, likely directories
		490	are files beginning with ".", or otherwise files with no dots,
		491	of which files with short names are tried first.
		492
		493	IO::AIO::READDIR_STAT_ORDER
		494	When this flag is set, then the names will be returned in an
		495	order suitable for stat()'ing each one. That is, when you plan
		496	to stat() all files in the given directory, then the returned
		497	order will likely be fastest.
		498
		499	If both this flag and "IO::AIO::READDIR_DIRS_FIRST" are
		500	specified, then the likely dirs come first, resulting in a less
		501	optimal stat order.
		502
		503	IO::AIO::READDIR_FOUND_UNKNOWN
		504	This flag should not be set when calling "aio_readdirx".
		505	Instead, it is being set by "aio_readdirx", when any of the
		506	$type's found were "IO::AIO::DT_UNKNOWN". The absense of this
		507	flag therefore indicates that all $type's are known, which can
		508	be used to speed up some algorithms.
		509
		510	aio_load $path, $data, $callback->($status)
		511	This is a composite request that tries to fully load the given file
		512	into memory. Status is the same as with aio_read.
		513
		514	aio_copy $srcpath, $dstpath, $callback->($status)
		515	Try to copy the file (directories not supported as either source
		516	or destination) from $srcpath to $dstpath and call the callback with
		517	the 0 (error) or -1 ok.
		518
		519	This is a composite request that creates the destination file with
		520	mode 0200 and copies the contents of the source file into it using
		521	"aio_sendfile", followed by restoring atime, mtime, access mode and
		522	uid/gid, in that order.
		523
		524	If an error occurs, the partial destination file will be unlinked,
		525	if possible, except when setting atime, mtime, access mode and
		526	uid/gid, where errors are being ignored.
		527
		528	aio_move $srcpath, $dstpath, $callback->($status)
		529	Try to move the file (directories not supported as either source
		530	or destination) from $srcpath to $dstpath and call the callback with
		531	the 0 (error) or -1 ok.
		532
		533	This is a composite request that tries to rename(2) the file first;
		534	if rename fails with "EXDEV", it copies the file with "aio_copy"
		535	and, if that is successful, unlinks the $srcpath.
		536
		537	aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
		538	Scans a directory (similar to "aio_readdir") but additionally tries
		539	to efficiently separate the entries of directory $path into two sets
		540	of names, directories you can recurse into (directories), and ones
		541	you cannot recurse into (everything else, including symlinks to
		542	directories).
		543
		544	"aio_scandir" is a composite request that creates of many sub
		545	requests_ $maxreq specifies the maximum number of outstanding aio
		546	requests that this function generates. If it is "<= 0", then a
		547	suitable default will be chosen (currently 4).
		548
		549	On error, the callback is called without arguments, otherwise it
		550	receives two array-refs with path-relative entry names.
		551
		552	Example:
		553
		554	aio_scandir $dir, 0, sub {
		555	my ($dirs, $nondirs) = @_;
		556	print "real directories: @$dirs\n";
		557	print "everything else: @$nondirs\n";
		558	};
		559
		560	Implementation notes.
		561
		562	The "aio_readdir" cannot be avoided, but "stat()"'ing every entry
		563	can.
		564
		565	If readdir returns file type information, then this is used directly
		566	to find directories.
		567
		568	Otherwise, after reading the directory, the modification time, size
		569	etc. of the directory before and after the readdir is checked, and
		570	if they match (and isn't the current time), the link count will be
		571	used to decide how many entries are directories (if >= 2).
		572	Otherwise, no knowledge of the number of subdirectories will be
		573	assumed.
		574
		575	Then entries will be sorted into likely directories a non-initial
		576	dot currently) and likely non-directories (see "aio_readdirx"). Then
		577	every entry plus an appended "/." will be "stat"'ed, likely
		578	directories first, in order of their inode numbers. If that
		579	succeeds, it assumes that the entry is a directory or a symlink to
		580	directory (which will be checked seperately). This is often faster
		581	than stat'ing the entry itself because filesystems might detect the
		582	type of the entry without reading the inode data (e.g. ext2fs
		583	filetype feature), even on systems that cannot return the filetype
		584	information on readdir.
		585
		586	If the known number of directories (link count - 2) has been
		587	reached, the rest of the entries is assumed to be non-directories.
		588
		589	This only works with certainty on POSIX (= UNIX) filesystems, which
		590	fortunately are the vast majority of filesystems around.
		591
		592	It will also likely work on non-POSIX filesystems with reduced
		593	efficiency as those tend to return 0 or 1 as link counts, which
		594	disables the directory counting heuristic.
		595
		596	aio_rmtree $path, $callback->($status)
		597	Delete a directory tree starting (and including) $path, return the
		598	status of the final "rmdir" only. This is a composite request that
		599	uses "aio_scandir" to recurse into and rmdir directories, and unlink
		600	everything else.
		601
		602	aio_sync $callback->($status)
		603	Asynchronously call sync and call the callback when finished.
		604
125	aio_fsync $fh, $callback	605	aio_fsync $fh, $callback->($status)
126	Asynchronously call fsync on the given filehandle and call the	606	Asynchronously call fsync on the given filehandle and call the
127	callback with the fsync result code.	607	callback with the fsync result code.
128		608
129	aio_fdatasync $fh, $callback	609	aio_fdatasync $fh, $callback->($status)
130	Asynchronously call fdatasync on the given filehandle and call the	610	Asynchronously call fdatasync on the given filehandle and call the
131	callback with the fdatasync result code.	611	callback with the fdatasync result code.
132		612
		613	If this call isn't available because your OS lacks it or it couldn't
		614	be detected, it will be emulated by calling "fsync" instead.
		615
		616	aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
		617	Sync the data portion of the file specified by $offset and $length
		618	to disk (but NOT the metadata), by calling the Linux-specific
		619	sync_file_range call. If sync_file_range is not available or it
		620	returns ENOSYS, then fdatasync or fsync is being substituted.
		621
		622	$flags can be a combination of
		623	"IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE",
		624	"IO::AIO::SYNC_FILE_RANGE_WRITE" and
		625	"IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER": refer to the sync_file_range
		626	manpage for details.
		627
		628	aio_pathsync $path, $callback->($status)
		629	This request tries to open, fsync and close the given path. This is
		630	a composite request intended to sync directories after directory
		631	operations (E.g. rename). This might not work on all operating
		632	systems or have any specific effect, but usually it makes sure that
		633	directory changes get written to disc. It works for anything that
		634	can be opened for read-only, not just directories.
		635
		636	Passes 0 when everything went ok, and -1 on error.
		637
		638	aio_group $callback->(...)
		639	This is a very special aio request: Instead of doing something, it
		640	is a container for other aio requests, which is useful if you want
		641	to bundle many requests into a single, composite, request with a
		642	definite callback and the ability to cancel the whole request with
		643	its subrequests.
		644
		645	Returns an object of class IO::AIO::GRP. See its documentation below
		646	for more info.
		647
		648	Example:
		649
		650	my $grp = aio_group sub {
		651	print "all stats done\n";
		652	};
		653
		654	add $grp
		655	(aio_stat ...),
		656	(aio_stat ...),
		657	...;
		658
		659	aio_nop $callback->()
		660	This is a special request - it does nothing in itself and is only
		661	used for side effects, such as when you want to add a dummy request
		662	to a group so that finishing the requests in the group depends on
		663	executing the given code.
		664
		665	While this request does nothing, it still goes through the execution
		666	phase and still requires a worker thread. Thus, the callback will
		667	not be executed immediately but only after other requests in the
		668	queue have entered their execution phase. This can be used to
		669	measure request latency.
		670
		671	IO::AIO::aio_busy $fractional_seconds, $callback->() NOT EXPORTED
		672	Mainly used for debugging and benchmarking, this aio request puts
		673	one of the request workers to sleep for the given time.
		674
		675	While it is theoretically handy to have simple I/O scheduling
		676	requests like sleep and file handle readable/writable, the overhead
		677	this creates is immense (it blocks a thread for a long time) so do
		678	not use this function except to put your application under
		679	artificial I/O pressure.
		680
		681	IO::AIO::REQ CLASS
		682	All non-aggregate "aio_*" functions return an object of this class when
		683	called in non-void context.
		684
		685	cancel $req
		686	Cancels the request, if possible. Has the effect of skipping
		687	execution when entering the execute state and skipping calling the
		688	callback when entering the the result state, but will leave the
		689	request otherwise untouched (with the exception of readdir). That
		690	means that requests that currently execute will not be stopped and
		691	resources held by the request will not be freed prematurely.
		692
		693	cb $req $callback->(...)
		694	Replace (or simply set) the callback registered to the request.
		695
		696	IO::AIO::GRP CLASS
		697	This class is a subclass of IO::AIO::REQ, so all its methods apply to
		698	objects of this class, too.
		699
		700	A IO::AIO::GRP object is a special request that can contain multiple
		701	other aio requests.
		702
		703	You create one by calling the "aio_group" constructing function with a
		704	callback that will be called when all contained requests have entered
		705	the "done" state:
		706
		707	my $grp = aio_group sub {
		708	print "all requests are done\n";
		709	};
		710
		711	You add requests by calling the "add" method with one or more
		712	"IO::AIO::REQ" objects:
		713
		714	$grp->add (aio_unlink "...");
		715
		716	add $grp aio_stat "...", sub {
		717	$_[0] or return $grp->result ("error");
		718
		719	# add another request dynamically, if first succeeded
		720	add $grp aio_open "...", sub {
		721	$grp->result ("ok");
		722	};
		723	};
		724
		725	This makes it very easy to create composite requests (see the source of
		726	"aio_move" for an application) that work and feel like simple requests.
		727
		728	* The IO::AIO::GRP objects will be cleaned up during calls to
		729	"IO::AIO::poll_cb", just like any other request.
		730
		731	* They can be canceled like any other request. Canceling will cancel
		732	not only the request itself, but also all requests it contains.
		733
		734	* They can also can also be added to other IO::AIO::GRP objects.
		735
		736	* You must not add requests to a group from within the group callback
		737	(or any later time).
		738
		739	Their lifetime, simplified, looks like this: when they are empty, they
		740	will finish very quickly. If they contain only requests that are in the
		741	"done" state, they will also finish. Otherwise they will continue to
		742	exist.
		743
		744	That means after creating a group you have some time to add requests
		745	(precisely before the callback has been invoked, which is only done
		746	within the "poll_cb"). And in the callbacks of those requests, you can
		747	add further requests to the group. And only when all those requests have
		748	finished will the the group itself finish.
		749
		750	add $grp ...
		751	$grp->add (...)
		752	Add one or more requests to the group. Any type of IO::AIO::REQ can
		753	be added, including other groups, as long as you do not create
		754	circular dependencies.
		755
		756	Returns all its arguments.
		757
		758	$grp->cancel_subs
		759	Cancel all subrequests and clears any feeder, but not the group
		760	request itself. Useful when you queued a lot of events but got a
		761	result early.
		762
		763	$grp->result (...)
		764	Set the result value(s) that will be passed to the group callback
		765	when all subrequests have finished and set the groups errno to the
		766	current value of errno (just like calling "errno" without an error
		767	number). By default, no argument will be passed and errno is zero.
		768
		769	$grp->errno ([$errno])
		770	Sets the group errno value to $errno, or the current value of errno
		771	when the argument is missing.
		772
		773	Every aio request has an associated errno value that is restored
		774	when the callback is invoked. This method lets you change this value
		775	from its default (0).
		776
		777	Calling "result" will also set errno, so make sure you either set $!
		778	before the call to "result", or call c<errno> after it.
		779
		780	feed $grp $callback->($grp)
		781	Sets a feeder/generator on this group: every group can have an
		782	attached generator that generates requests if idle. The idea behind
		783	this is that, although you could just queue as many requests as you
		784	want in a group, this might starve other requests for a potentially
		785	long time. For example, "aio_scandir" might generate hundreds of
		786	thousands "aio_stat" requests, delaying any later requests for a
		787	long time.
		788
		789	To avoid this, and allow incremental generation of requests, you can
		790	instead a group and set a feeder on it that generates those
		791	requests. The feed callback will be called whenever there are few
		792	enough (see "limit", below) requests active in the group itself and
		793	is expected to queue more requests.
		794
		795	The feed callback can queue as many requests as it likes (i.e. "add"
		796	does not impose any limits).
		797
		798	If the feed does not queue more requests when called, it will be
		799	automatically removed from the group.
		800
		801	If the feed limit is 0 when this method is called, it will be set to
		802	2 automatically.
		803
		804	Example:
		805
		806	# stat all files in @files, but only ever use four aio requests concurrently:
		807
		808	my $grp = aio_group sub { print "finished\n" };
		809	limit $grp 4;
		810	feed $grp sub {
		811	my $file = pop @files
		812	or return;
		813
		814	add $grp aio_stat $file, sub { ... };
		815	};
		816
		817	limit $grp $num
		818	Sets the feeder limit for the group: The feeder will be called
		819	whenever the group contains less than this many requests.
		820
		821	Setting the limit to 0 will pause the feeding process.
		822
		823	The default value for the limit is 0, but note that setting a feeder
		824	automatically bumps it up to 2.
		825
133	SUPPORT FUNCTIONS	826	SUPPORT FUNCTIONS
		827	EVENT PROCESSING AND EVENT LOOP INTEGRATION
134	$fileno = IO::AIO::poll_fileno	828	$fileno = IO::AIO::poll_fileno
135	Return the request result pipe filehandle. This filehandle must be	829	Return the request result pipe file descriptor. This filehandle
136	polled for reading by some mechanism outside this module (e.g. Event	830	must be polled for reading by some mechanism outside this module
137	or select, see below). If the pipe becomes readable you have to call	831	(e.g. EV, Glib, select and so on, see below or the SYNOPSIS). If the
138	"poll_cb" to check the results.	832	pipe becomes readable you have to call "poll_cb" to check the
		833	results.
139		834
140	See "poll_cb" for an example.	835	See "poll_cb" for an example.
141		836
142	IO::AIO::poll_cb	837	IO::AIO::poll_cb
143	Process all outstanding events on the result pipe. You have to call	838	Process some outstanding events on the result pipe. You have to call
144	this regularly. Returns the number of events processed. Returns	839	this regularly. Returns 0 if all events could be processed, or -1 if
145	immediately when no events are outstanding.	840	it returned earlier for whatever reason. Returns immediately when no
		841	events are outstanding. The amount of events processed depends on
		842	the settings of "IO::AIO::max_poll_req" and
		843	"IO::AIO::max_poll_time".
146		844
147	You can use Event to multiplex, e.g.:	845	If not all requests were processed for whatever reason, the
		846	filehandle will still be ready when "poll_cb" returns, so normally
		847	you don't have to do anything special to have it called later.
		848
		849	Example: Install an Event watcher that automatically calls
		850	IO::AIO::poll_cb with high priority (more examples can be found in
		851	the SYNOPSIS section, at the top of this document):
148		852
149	Event->io (fd => IO::AIO::poll_fileno,	853	Event->io (fd => IO::AIO::poll_fileno,
150	poll => 'r', async => 1,	854	poll => 'r', async => 1,
151	cb => \&IO::AIO::poll_cb);	855	cb => \&IO::AIO::poll_cb);
152		856
		857	IO::AIO::max_poll_reqs $nreqs
		858	IO::AIO::max_poll_time $seconds
		859	These set the maximum number of requests (default 0, meaning
		860	infinity) that are being processed by "IO::AIO::poll_cb" in one
		861	call, respectively the maximum amount of time (default 0, meaning
		862	infinity) spent in "IO::AIO::poll_cb" to process requests (more
		863	correctly the mininum amount of time "poll_cb" is allowed to use).
		864
		865	Setting "max_poll_time" to a non-zero value creates an overhead of
		866	one syscall per request processed, which is not normally a problem
		867	unless your callbacks are really really fast or your OS is really
		868	really slow (I am not mentioning Solaris here). Using
		869	"max_poll_reqs" incurs no overhead.
		870
		871	Setting these is useful if you want to ensure some level of
		872	interactiveness when perl is not fast enough to process all requests
		873	in time.
		874
		875	For interactive programs, values such as 0.01 to 0.1 should be fine.
		876
		877	Example: Install an Event watcher that automatically calls
		878	IO::AIO::poll_cb with low priority, to ensure that other parts of
		879	the program get the CPU sometimes even under high AIO load.
		880
		881	# try not to spend much more than 0.1s in poll_cb
		882	IO::AIO::max_poll_time 0.1;
		883
		884	# use a low priority so other tasks have priority
		885	Event->io (fd => IO::AIO::poll_fileno,
		886	poll => 'r', nice => 1,
		887	cb => &IO::AIO::poll_cb);
		888
153	IO::AIO::poll_wait	889	IO::AIO::poll_wait
		890	If there are any outstanding requests and none of them in the result
154	Wait till the result filehandle becomes ready for reading (simply	891	phase, wait till the result filehandle becomes ready for reading
155	does a select on the filehandle. This is useful if you want to	892	(simply does a "select" on the filehandle. This is useful if you
156	synchronously wait for some requests to finish).	893	want to synchronously wait for some requests to finish).
157		894
158	See "nreqs" for an example.	895	See "nreqs" for an example.
159		896
		897	IO::AIO::poll
		898	Waits until some requests have been handled.
		899
		900	Returns the number of requests processed, but is otherwise strictly
		901	equivalent to:
		902
		903	IO::AIO::poll_wait, IO::AIO::poll_cb
		904
160	IO::AIO::nreqs	905	IO::AIO::flush
161	Returns the number of requests currently outstanding.	906	Wait till all outstanding AIO requests have been handled.
162		907
163	Example: wait till there are no outstanding requests anymore:	908	Strictly equivalent to:
164		909
165	IO::AIO::poll_wait, IO::AIO::poll_cb	910	IO::AIO::poll_wait, IO::AIO::poll_cb
166	while IO::AIO::nreqs;	911	while IO::AIO::nreqs;
167		912
		913	CONTROLLING THE NUMBER OF THREADS
168	IO::AIO::min_parallel $nthreads	914	IO::AIO::min_parallel $nthreads
169	Set the minimum number of AIO threads to $nthreads. The default is	915	Set the minimum number of AIO threads to $nthreads. The current
170	1, which means a single asynchronous operation can be done at one	916	default is 8, which means eight asynchronous operations can execute
171	time (the number of outstanding operations, however, is unlimited).	917	concurrently at any one time (the number of outstanding requests,
		918	however, is unlimited).
172		919
		920	IO::AIO starts threads only on demand, when an AIO request is queued
		921	and no free thread exists. Please note that queueing up a hundred
		922	requests can create demand for a hundred threads, even if it turns
		923	out that everything is in the cache and could have been processed
		924	faster by a single thread.
		925
173	It is recommended to keep the number of threads low, as some Linux	926	It is recommended to keep the number of threads relatively low, as
174	kernel versions will scale negatively with the number of threads	927	some Linux kernel versions will scale negatively with the number of
175	(higher parallelity => MUCH higher latency). With current Linux 2.6	928	threads (higher parallelity => MUCH higher latency). With current
176	versions, 4-32 threads should be fine.	929	Linux 2.6 versions, 4-32 threads should be fine.
177		930
178	Under normal circumstances you don't need to call this function, as	931	Under most circumstances you don't need to call this function, as
179	this module automatically starts some threads (the exact number	932	the module selects a default that is suitable for low to moderate
180	might change, and is currently 4).	933	load.
181		934
182	IO::AIO::max_parallel $nthreads	935	IO::AIO::max_parallel $nthreads
183	Sets the maximum number of AIO threads to $nthreads. If more than	936	Sets the maximum number of AIO threads to $nthreads. If more than
184	the specified number of threads are currently running, kill them.	937	the specified number of threads are currently running, this function
185	This function blocks until the limit is reached.	938	kills them. This function blocks until the limit is reached.
		939
		940	While $nthreads are zero, aio requests get queued but not executed
		941	until the number of threads has been increased again.
186		942
187	This module automatically runs "max_parallel 0" at program end, to	943	This module automatically runs "max_parallel 0" at program end, to
188	ensure that all threads are killed and that there are no outstanding	944	ensure that all threads are killed and that there are no outstanding
189	requests.	945	requests.
190		946
191	Under normal circumstances you don't need to call this function.	947	Under normal circumstances you don't need to call this function.
192		948
		949	IO::AIO::max_idle $nthreads
		950	Limit the number of threads (default: 4) that are allowed to idle
		951	(i.e., threads that did not get a request to process within 10
		952	seconds). That means if a thread becomes idle while $nthreads other
		953	threads are also idle, it will free its resources and exit.
		954
		955	This is useful when you allow a large number of threads (e.g. 100 or
		956	1000) to allow for extremely high load situations, but want to free
		957	resources under normal circumstances (1000 threads can easily
		958	consume 30MB of RAM).
		959
		960	The default is probably ok in most situations, especially if thread
		961	creation is fast. If thread creation is very slow on your system you
		962	might want to use larger values.
		963
193	$oldnreqs = IO::AIO::max_outstanding $nreqs	964	IO::AIO::max_outstanding $maxreqs
		965	This is a very bad function to use in interactive programs because
		966	it blocks, and a bad way to reduce concurrency because it is
		967	inexact: Better use an "aio_group" together with a feed callback.
		968
194	Sets the maximum number of outstanding requests to $nreqs. If you	969	Sets the maximum number of outstanding requests to $nreqs. If you do
195	try to queue up more than this number of requests, the caller will	970	queue up more than this number of requests, the next call to the
196	block until some requests have been handled.	971	"poll_cb" (and "poll_some" and other functions calling "poll_cb")
		972	function will block until the limit is no longer exceeded.
197		973
198	The default is very large, so normally there is no practical limit.	974	The default value is very large, so there is no practical limit on
199	If you queue up many requests in a loop it it often improves speed	975	the number of outstanding requests.
200	if you set this to a relatively low number, such as 100.
201		976
202	Under normal circumstances you don't need to call this function.	977	You can still queue as many requests as you want. Therefore,
		978	"max_outstanding" is mainly useful in simple scripts (with low
		979	values) or as a stop gap to shield against fatal memory overflow
		980	(with large values).
		981
		982	STATISTICAL INFORMATION
		983	IO::AIO::nreqs
		984	Returns the number of requests currently in the ready, execute or
		985	pending states (i.e. for which their callback has not been invoked
		986	yet).
		987
		988	Example: wait till there are no outstanding requests anymore:
		989
		990	IO::AIO::poll_wait, IO::AIO::poll_cb
		991	while IO::AIO::nreqs;
		992
		993	IO::AIO::nready
		994	Returns the number of requests currently in the ready state (not yet
		995	executed).
		996
		997	IO::AIO::npending
		998	Returns the number of requests currently in the pending state
		999	(executed, but not yet processed by poll_cb).
		1000
		1001	MISCELLANEOUS FUNCTIONS
		1002	IO::AIO implements some functions that might be useful, but are not
		1003	asynchronous.
		1004
		1005	IO::AIO::sendfile $ofh, $ifh, $offset, $count
		1006	Calls the "eio_sendfile_sync" function, which is like
		1007	"aio_sendfile", but is blocking (this makes most sense if you know
		1008	the input data is likely cached already and the output filehandle is
		1009	set to non-blocking operations).
		1010
		1011	Returns the number of bytes copied, or -1 on error.
		1012
		1013	IO::AIO::fadvise $fh, $offset, $len, $advice
		1014	Simply calls the "posix_fadvise" function (see it's manpage for
		1015	details). The following advice constants are avaiable:
		1016	"IO::AIO::FADV_NORMAL", "IO::AIO::FADV_SEQUENTIAL",
		1017	"IO::AIO::FADV_RANDOM", "IO::AIO::FADV_NOREUSE",
		1018	"IO::AIO::FADV_WILLNEED", "IO::AIO::FADV_DONTNEED".
		1019
		1020	On systems that do not implement "posix_fadvise", this function
		1021	returns ENOSYS, otherwise the return value of "posix_fadvise".
		1022
		1023	FORK BEHAVIOUR
		1024	This module should do "the right thing" when the process using it forks:
		1025
		1026	Before the fork, IO::AIO enters a quiescent state where no requests can
		1027	be added in other threads and no results will be processed. After the
		1028	fork the parent simply leaves the quiescent state and continues
		1029	request/result processing, while the child frees the request/result
		1030	queue (so that the requests started before the fork will only be handled
		1031	in the parent). Threads will be started on demand until the limit set in
		1032	the parent process has been reached again.
		1033
		1034	In short: the parent will, after a short pause, continue as if fork had
		1035	not been called, while the child will act as if IO::AIO has not been
		1036	used yet.
		1037
		1038	MEMORY USAGE
		1039	Per-request usage:
		1040
		1041	Each aio request uses - depending on your architecture - around 100-200
		1042	bytes of memory. In addition, stat requests need a stat buffer (possibly
		1043	a few hundred bytes), readdir requires a result buffer and so on. Perl
		1044	scalars and other data passed into aio requests will also be locked and
		1045	will consume memory till the request has entered the done state.
		1046
		1047	This is not awfully much, so queuing lots of requests is not usually a
		1048	problem.
		1049
		1050	Per-thread usage:
		1051
		1052	In the execution phase, some aio requests require more memory for
		1053	temporary buffers, and each thread requires a stack and other data
		1054	structures (usually around 16k-128k, depending on the OS).
		1055
		1056	KNOWN BUGS
		1057	Known bugs will be fixed in the next release.
203		1058
204	SEE ALSO	1059	SEE ALSO
205	Coro, Linux::AIO.	1060	AnyEvent::AIO for easy integration into event loops, Coro::AIO for a
		1061	more natural syntax.
206		1062
207	AUTHOR	1063	AUTHOR
208	Marc Lehmann <schmorp@schmorp.de>	1064	Marc Lehmann <schmorp@schmorp.de>
209	http://home.schmorp.de/	1065	http://home.schmorp.de/
210		1066

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Comparing IO-AIO/README (file contents):
Revision 1.4 by root, Sun Jul 10 21:04:46 2005 UTC vs.
Revision 1.38 by root, Sat Jun 27 03:19:27 2009 UTC