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

Comparing IO-AIO/README (file contents):
Revision 1.43 by root, Sun Jan 10 23:44:02 2010 UTC vs.
Revision 1.58 by root, Sun May 1 17:19:39 2016 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
…		…
64		64
65	EXAMPLE	65	EXAMPLE
66	This is a simple example that uses the EV module and loads /etc/passwd	66	This is a simple example that uses the EV module and loads /etc/passwd
67	asynchronously:	67	asynchronously:
68		68
69	use Fcntl;
70	use EV;	69	use EV;
71	use IO::AIO;	70	use IO::AIO;
72		71
73	# register the IO::AIO callback with EV	72	# register the IO::AIO callback with EV
74	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;	73	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
75		74
76	# queue the request to open /etc/passwd	75	# queue the request to open /etc/passwd
77	aio_open "/etc/passwd", O_RDONLY, 0, sub {	76	aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
78	my $fh = shift	77	my $fh = shift
79	or die "error while opening: $!";	78	or die "error while opening: $!";
80		79
81	# stat'ing filehandles is generally non-blocking	80	# stat'ing filehandles is generally non-blocking
82	my $size = -s $fh;	81	my $size = -s $fh;
…		…
91		90
92	# file contents now in $contents	91	# file contents now in $contents
93	print $contents;	92	print $contents;
94		93
95	# exit event loop and program	94	# exit event loop and program
96	EV::unloop;	95	EV::break;
97	};	96	};
98	};	97	};
99		98
100	# possibly queue up other requests, or open GUI windows,	99	# possibly queue up other requests, or open GUI windows,
101	# check for sockets etc. etc.	100	# check for sockets etc. etc.
102		101
103	# process events as long as there are some:	102	# process events as long as there are some:
104	EV::loop;	103	EV::run;
105		104
106	REQUEST ANATOMY AND LIFETIME	105	REQUEST ANATOMY AND LIFETIME
107	Every "aio_*" function creates a request. which is a C data structure	106	Every "aio_*" function creates a request. which is a C data structure
108	not directly visible to Perl.	107	not directly visible to Perl.
109		108
…		…
146	the actual aio request is severed and calling its methods will	145	the actual aio request is severed and calling its methods will
147	either do nothing or result in a runtime error).	146	either do nothing or result in a runtime error).
148		147
149	FUNCTIONS	148	FUNCTIONS
150	QUICK OVERVIEW	149	QUICK OVERVIEW
151	This section simply lists the prototypes of the most important functions	150	This section simply lists the prototypes most of the functions for quick
152	for quick reference. See the following sections for function-by-function	151	reference. See the following sections for function-by-function
153	documentation.	152	documentation.
154		153
		154	aio_wd $pathname, $callback->($wd)
155	aio_open $pathname, $flags, $mode, $callback->($fh)	155	aio_open $pathname, $flags, $mode, $callback->($fh)
156	aio_close $fh, $callback->($status)	156	aio_close $fh, $callback->($status)
		157	aio_seek $fh,$offset,$whence, $callback->($offs)
157	aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	158	aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
158	aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	159	aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
159	aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)	160	aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
160	aio_readahead $fh,$offset,$length, $callback->($retval)	161	aio_readahead $fh,$offset,$length, $callback->($retval)
161	aio_stat $fh_or_path, $callback->($status)	162	aio_stat $fh_or_path, $callback->($status)
162	aio_lstat $fh, $callback->($status)	163	aio_lstat $fh, $callback->($status)
163	aio_statvfs $fh_or_path, $callback->($statvfs)	164	aio_statvfs $fh_or_path, $callback->($statvfs)
164	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)	165	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
165	aio_chown $fh_or_path, $uid, $gid, $callback->($status)	166	aio_chown $fh_or_path, $uid, $gid, $callback->($status)
		167	aio_chmod $fh_or_path, $mode, $callback->($status)
166	aio_truncate $fh_or_path, $offset, $callback->($status)	168	aio_truncate $fh_or_path, $offset, $callback->($status)
167	aio_chmod $fh_or_path, $mode, $callback->($status)	169	aio_allocate $fh, $mode, $offset, $len, $callback->($status)
		170	aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
168	aio_unlink $pathname, $callback->($status)	171	aio_unlink $pathname, $callback->($status)
169	aio_mknod $path, $mode, $dev, $callback->($status)	172	aio_mknod $pathname, $mode, $dev, $callback->($status)
170	aio_link $srcpath, $dstpath, $callback->($status)	173	aio_link $srcpath, $dstpath, $callback->($status)
171	aio_symlink $srcpath, $dstpath, $callback->($status)	174	aio_symlink $srcpath, $dstpath, $callback->($status)
172	aio_readlink $path, $callback->($link)	175	aio_readlink $pathname, $callback->($link)
		176	aio_realpath $pathname, $callback->($path)
173	aio_rename $srcpath, $dstpath, $callback->($status)	177	aio_rename $srcpath, $dstpath, $callback->($status)
174	aio_mkdir $pathname, $mode, $callback->($status)	178	aio_mkdir $pathname, $mode, $callback->($status)
175	aio_rmdir $pathname, $callback->($status)	179	aio_rmdir $pathname, $callback->($status)
176	aio_readdir $pathname, $callback->($entries)	180	aio_readdir $pathname, $callback->($entries)
177	aio_readdirx $pathname, $flags, $callback->($entries, $flags)	181	aio_readdirx $pathname, $flags, $callback->($entries, $flags)
178	IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST	182	IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST
179	IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN	183	IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN
		184	aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
180	aio_load $path, $data, $callback->($status)	185	aio_load $pathname, $data, $callback->($status)
181	aio_copy $srcpath, $dstpath, $callback->($status)	186	aio_copy $srcpath, $dstpath, $callback->($status)
182	aio_move $srcpath, $dstpath, $callback->($status)	187	aio_move $srcpath, $dstpath, $callback->($status)
183	aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
184	aio_rmtree $path, $callback->($status)	188	aio_rmtree $pathname, $callback->($status)
		189	aio_fcntl $fh, $cmd, $arg, $callback->($status)
		190	aio_ioctl $fh, $request, $buf, $callback->($status)
185	aio_sync $callback->($status)	191	aio_sync $callback->($status)
		192	aio_syncfs $fh, $callback->($status)
186	aio_fsync $fh, $callback->($status)	193	aio_fsync $fh, $callback->($status)
187	aio_fdatasync $fh, $callback->($status)	194	aio_fdatasync $fh, $callback->($status)
188	aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)	195	aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
189	aio_pathsync $path, $callback->($status)	196	aio_pathsync $pathname, $callback->($status)
190	aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)	197	aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
191	aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)	198	aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		199	aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
		200	aio_mlockall $flags, $callback->($status)
192	aio_group $callback->(...)	201	aio_group $callback->(...)
193	aio_nop $callback->()	202	aio_nop $callback->()
194		203
195	$prev_pri = aioreq_pri [$pri]	204	$prev_pri = aioreq_pri [$pri]
196	aioreq_nice $pri_adjust	205	aioreq_nice $pri_adjust
…		…
202	IO::AIO::max_poll_reqs $nreqs	211	IO::AIO::max_poll_reqs $nreqs
203	IO::AIO::max_poll_time $seconds	212	IO::AIO::max_poll_time $seconds
204	IO::AIO::min_parallel $nthreads	213	IO::AIO::min_parallel $nthreads
205	IO::AIO::max_parallel $nthreads	214	IO::AIO::max_parallel $nthreads
206	IO::AIO::max_idle $nthreads	215	IO::AIO::max_idle $nthreads
		216	IO::AIO::idle_timeout $seconds
207	IO::AIO::max_outstanding $maxreqs	217	IO::AIO::max_outstanding $maxreqs
208	IO::AIO::nreqs	218	IO::AIO::nreqs
209	IO::AIO::nready	219	IO::AIO::nready
210	IO::AIO::npending	220	IO::AIO::npending
211		221
212	IO::AIO::sendfile $ofh, $ifh, $offset, $count	222	IO::AIO::sendfile $ofh, $ifh, $offset, $count
213	IO::AIO::fadvise $fh, $offset, $len, $advice	223	IO::AIO::fadvise $fh, $offset, $len, $advice
214	IO::AIO::mlockall $flags	224	IO::AIO::mmap $scalar, $length, $prot, $flags[, $fh[, $offset]]
		225	IO::AIO::munmap $scalar
		226	IO::AIO::madvise $scalar, $offset, $length, $advice
		227	IO::AIO::mprotect $scalar, $offset, $length, $protect
		228	IO::AIO::munlock $scalar, $offset = 0, $length = undef
215	IO::AIO::munlockall	229	IO::AIO::munlockall
216		230
217	AIO REQUEST FUNCTIONS	231	API NOTES
218	All the "aio_*" calls are more or less thin wrappers around the syscall	232	All the "aio_*" calls are more or less thin wrappers around the syscall
219	with the same name (sans "aio_"). The arguments are similar or	233	with the same name (sans "aio_"). The arguments are similar or
220	identical, and they all accept an additional (and optional) $callback	234	identical, and they all accept an additional (and optional) $callback
221	argument which must be a code reference. This code reference will get	235	argument which must be a code reference. This code reference will be
222	called with the syscall return code (e.g. most syscalls return -1 on
223	error, unlike perl, which usually delivers "false") as its sole argument
224	after the given syscall has been executed asynchronously.	236	called after the syscall has been executed in an asynchronous fashion.
		237	The results of the request will be passed as arguments to the callback
		238	(and, if an error occured, in $!) - for most requests the syscall return
		239	code (e.g. most syscalls return -1 on error, unlike perl, which usually
		240	delivers "false").
		241
		242	Some requests (such as "aio_readdir") pass the actual results and
		243	communicate failures by passing "undef".
225		244
226	All functions expecting a filehandle keep a copy of the filehandle	245	All functions expecting a filehandle keep a copy of the filehandle
227	internally until the request has finished.	246	internally until the request has finished.
228		247
229	All functions return request objects of type IO::AIO::REQ that allow	248	All functions return request objects of type IO::AIO::REQ that allow
230	further manipulation of those requests while they are in-flight.	249	further manipulation of those requests while they are in-flight.
231		250
232	The pathnames you pass to these routines must be absolute and encoded	251	The pathnames you pass to these routines should be absolute. The
233	as octets. The reason for the former is that at the time the request is	252	reason for this is that at the time the request is being executed, the
234	being executed, the current working directory could have changed.	253	current working directory could have changed. Alternatively, you can
235	Alternatively, you can make sure that you never change the current	254	make sure that you never change the current working directory anywhere
236	working directory anywhere in the program and then use relative paths.	255	in the program and then use relative paths. You can also take advantage
		256	of IO::AIOs working directory abstraction, that lets you specify paths
		257	relative to some previously-opened "working directory object" - see the
		258	description of the "IO::AIO::WD" class later in this document.
237		259
238	To encode pathnames as octets, either make sure you either: a) always	260	To encode pathnames as octets, either make sure you either: a) always
239	pass in filenames you got from outside (command line, readdir etc.)	261	pass in filenames you got from outside (command line, readdir etc.)
240	without tinkering, b) are ASCII or ISO 8859-1, c) use the Encode module	262	without tinkering, b) are in your native filesystem encoding, c) use the
241	and encode your pathnames to the locale (or other) encoding in effect in	263	Encode module and encode your pathnames to the locale (or other)
242	the user environment, d) use Glib::filename_from_unicode on unicode	264	encoding in effect in the user environment, d) use
243	filenames or e) use something else to ensure your scalar has the correct	265	Glib::filename_from_unicode on unicode filenames or e) use something
244	contents.	266	else to ensure your scalar has the correct contents.
245		267
246	This works, btw. independent of the internal UTF-8 bit, which IO::AIO	268	This works, btw. independent of the internal UTF-8 bit, which IO::AIO
247	handles correctly whether it is set or not.	269	handles correctly whether it is set or not.
248		270
		271	AIO REQUEST FUNCTIONS
249	$prev_pri = aioreq_pri [$pri]	272	$prev_pri = aioreq_pri [$pri]
250	Returns the priority value that would be used for the next request	273	Returns the priority value that would be used for the next request
251	and, if $pri is given, sets the priority for the next aio request.	274	and, if $pri is given, sets the priority for the next aio request.
252		275
253	The default priority is 0, the minimum and maximum priorities are -4	276	The default priority is 0, the minimum and maximum priorities are -4
…		…
275	Similar to "aioreq_pri", but subtracts the given value from the	298	Similar to "aioreq_pri", but subtracts the given value from the
276	current priority, so the effect is cumulative.	299	current priority, so the effect is cumulative.
277		300
278	aio_open $pathname, $flags, $mode, $callback->($fh)	301	aio_open $pathname, $flags, $mode, $callback->($fh)
279	Asynchronously open or create a file and call the callback with a	302	Asynchronously open or create a file and call the callback with a
280	newly created filehandle for the file.	303	newly created filehandle for the file (or "undef" in case of an
		304	error).
281		305
282	The pathname passed to "aio_open" must be absolute. See API NOTES,	306	The pathname passed to "aio_open" must be absolute. See API NOTES,
283	above, for an explanation.	307	above, for an explanation.
284		308
285	The $flags argument is a bitmask. See the "Fcntl" module for a list.	309	The $flags argument is a bitmask. See the "Fcntl" module for a list.
…		…
292	will be modified by the umask in effect then the request is being	316	will be modified by the umask in effect then the request is being
293	executed, so better never change the umask.	317	executed, so better never change the umask.
294		318
295	Example:	319	Example:
296		320
297	aio_open "/etc/passwd", O_RDONLY, 0, sub {	321	aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
298	if ($_[0]) {	322	if ($_[0]) {
299	print "open successful, fh is $_[0]\n";	323	print "open successful, fh is $_[0]\n";
300	...	324	...
301	} else {	325	} else {
302	die "open failed: $!\n";	326	die "open failed: $!\n";
303	}	327	}
304	};	328	};
305		329
		330	In addition to all the common open modes/flags ("O_RDONLY",
		331	"O_WRONLY", "O_RDWR", "O_CREAT", "O_TRUNC", "O_EXCL" and
		332	"O_APPEND"), the following POSIX and non-POSIX constants are
		333	available (missing ones on your system are, as usual, 0):
		334
		335	"O_ASYNC", "O_DIRECT", "O_NOATIME", "O_CLOEXEC", "O_NOCTTY",
		336	"O_NOFOLLOW", "O_NONBLOCK", "O_EXEC", "O_SEARCH", "O_DIRECTORY",
		337	"O_DSYNC", "O_RSYNC", "O_SYNC", "O_PATH", "O_TMPFILE", and
		338	"O_TTY_INIT".
		339
306	aio_close $fh, $callback->($status)	340	aio_close $fh, $callback->($status)
307	Asynchronously close a file and call the callback with the result	341	Asynchronously close a file and call the callback with the result
308	code.	342	code.
309		343
310	Unfortunately, you can't do this to perl. Perl insists very	344	Unfortunately, you can't do this to perl. Perl insists very
…		…
315	will use dup2 to overwrite the file descriptor with the write-end of	349	will use dup2 to overwrite the file descriptor with the write-end of
316	a pipe (the pipe fd will be created on demand and will be cached).	350	a pipe (the pipe fd will be created on demand and will be cached).
317		351
318	Or in other words: the file descriptor will be closed, but it will	352	Or in other words: the file descriptor will be closed, but it will
319	not be free for reuse until the perl filehandle is closed.	353	not be free for reuse until the perl filehandle is closed.
		354
		355	aio_seek $fh, $offset, $whence, $callback->($offs)
		356	Seeks the filehandle to the new $offset, similarly to perl's
		357	"sysseek". The $whence can use the traditional values (0 for
		358	"IO::AIO::SEEK_SET", 1 for "IO::AIO::SEEK_CUR" or 2 for
		359	"IO::AIO::SEEK_END").
		360
		361	The resulting absolute offset will be passed to the callback, or -1
		362	in case of an error.
		363
		364	In theory, the $whence constants could be different than the
		365	corresponding values from Fcntl, but perl guarantees they are the
		366	same, so don't panic.
		367
		368	As a GNU/Linux (and maybe Solaris) extension, also the constants
		369	"IO::AIO::SEEK_DATA" and "IO::AIO::SEEK_HOLE" are available, if they
		370	could be found. No guarantees about suitability for use in
		371	"aio_seek" or Perl's "sysseek" can be made though, although I would
		372	naively assume they "just work".
320		373
321	aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	374	aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
322	aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	375	aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
323	Reads or writes $length bytes from or to the specified $fh and	376	Reads or writes $length bytes from or to the specified $fh and
324	$offset into the scalar given by $data and offset $dataoffset and	377	$offset into the scalar given by $data and offset $dataoffset and
…		…
353	aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)	406	aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
354	Tries to copy $length bytes from $in_fh to $out_fh. It starts	407	Tries to copy $length bytes from $in_fh to $out_fh. It starts
355	reading at byte offset $in_offset, and starts writing at the current	408	reading at byte offset $in_offset, and starts writing at the current
356	file offset of $out_fh. Because of that, it is not safe to issue	409	file offset of $out_fh. Because of that, it is not safe to issue
357	more than one "aio_sendfile" per $out_fh, as they will interfere	410	more than one "aio_sendfile" per $out_fh, as they will interfere
358	with each other.	411	with each other. The same $in_fh works fine though, as this function
		412	does not move or use the file offset of $in_fh.
359		413
		414	Please note that "aio_sendfile" can read more bytes from $in_fh than
		415	are written, and there is no way to find out how many more bytes
		416	have been read from "aio_sendfile" alone, as "aio_sendfile" only
		417	provides the number of bytes written to $out_fh. Only if the result
		418	value equals $length one can assume that $length bytes have been
		419	read.
		420
		421	Unlike with other "aio_" functions, it makes a lot of sense to use
		422	"aio_sendfile" on non-blocking sockets, as long as one end
		423	(typically the $in_fh) is a file - the file I/O will then be
		424	asynchronous, while the socket I/O will be non-blocking. Note,
		425	however, that you can run into a trap where "aio_sendfile" reads
		426	some data with readahead, then fails to write all data, and when the
		427	socket is ready the next time, the data in the cache is already
		428	lost, forcing "aio_sendfile" to again hit the disk. Explicit
		429	"aio_read" + "aio_write" let's you better control resource usage.
		430
360	This call tries to make use of a native "sendfile" syscall to	431	This call tries to make use of a native "sendfile"-like syscall to
361	provide zero-copy operation. For this to work, $out_fh should refer	432	provide zero-copy operation. For this to work, $out_fh should refer
362	to a socket, and $in_fh should refer to an mmap'able file.	433	to a socket, and $in_fh should refer to an mmap'able file.
363		434
364	If a native sendfile cannot be found or it fails with "ENOSYS",	435	If a native sendfile cannot be found or it fails with "ENOSYS",
365	"ENOTSUP", "EOPNOTSUPP", "EAFNOSUPPORT", "EPROTOTYPE" or "ENOTSOCK",	436	"EINVAL", "ENOTSUP", "EOPNOTSUPP", "EAFNOSUPPORT", "EPROTOTYPE" or
366	it will be emulated, so you can call "aio_sendfile" on any type of	437	"ENOTSOCK", it will be emulated, so you can call "aio_sendfile" on
367	filehandle regardless of the limitations of the operating system.	438	any type of filehandle regardless of the limitations of the
		439	operating system.
368		440
369	Please note, however, that "aio_sendfile" can read more bytes from	441	As native sendfile syscalls (as practically any non-POSIX interface
370	$in_fh than are written, and there is no way to find out how many	442	hacked together in a hurry to improve benchmark numbers) tend to be
371	bytes have been read from "aio_sendfile" alone, as "aio_sendfile"	443	rather buggy on many systems, this implementation tries to work
372	only provides the number of bytes written to $out_fh. Only if the	444	around some known bugs in Linux and FreeBSD kernels (probably
373	result value equals $length one can assume that $length bytes have	445	others, too), but that might fail, so you really really should check
374	been read.	446	the return value of "aio_sendfile" - fewre bytes than expected might
		447	have been transferred.
375		448
376	aio_readahead $fh,$offset,$length, $callback->($retval)	449	aio_readahead $fh,$offset,$length, $callback->($retval)
377	"aio_readahead" populates the page cache with data from a file so	450	"aio_readahead" populates the page cache with data from a file so
378	that subsequent reads from that file will not block on disk I/O. The	451	that subsequent reads from that file will not block on disk I/O. The
379	$offset argument specifies the starting point from which data is to	452	$offset argument specifies the starting point from which data is to
…		…
399		472
400	Currently, the stats are always 64-bit-stats, i.e. instead of	473	Currently, the stats are always 64-bit-stats, i.e. instead of
401	returning an error when stat'ing a large file, the results will be	474	returning an error when stat'ing a large file, the results will be
402	silently truncated unless perl itself is compiled with large file	475	silently truncated unless perl itself is compiled with large file
403	support.	476	support.
		477
		478	To help interpret the mode and dev/rdev stat values, IO::AIO offers
		479	the following constants and functions (if not implemented, the
		480	constants will be 0 and the functions will either "croak" or fall
		481	back on traditional behaviour).
		482
		483	"S_IFMT", "S_IFIFO", "S_IFCHR", "S_IFBLK", "S_IFLNK", "S_IFREG",
		484	"S_IFDIR", "S_IFWHT", "S_IFSOCK", "IO::AIO::major $dev_t",
		485	"IO::AIO::minor $dev_t", "IO::AIO::makedev $major, $minor".
404		486
405	Example: Print the length of /etc/passwd:	487	Example: Print the length of /etc/passwd:
406		488
407	aio_stat "/etc/passwd", sub {	489	aio_stat "/etc/passwd", sub {
408	$_[0] and die "stat failed: $!";	490	$_[0] and die "stat failed: $!";
…		…
450	namemax => 255,	532	namemax => 255,
451	frsize => 1024,	533	frsize => 1024,
452	fsid => 1810	534	fsid => 1810
453	}	535	}
454		536
		537	Here is a (likely partial - send me updates!) list of fsid values
		538	used by Linux - it is safe to hardcode these when $^O is "linux":
		539
		540	0x0000adf5 adfs
		541	0x0000adff affs
		542	0x5346414f afs
		543	0x09041934 anon-inode filesystem
		544	0x00000187 autofs
		545	0x42465331 befs
		546	0x1badface bfs
		547	0x42494e4d binfmt_misc
		548	0x9123683e btrfs
		549	0x0027e0eb cgroupfs
		550	0xff534d42 cifs
		551	0x73757245 coda
		552	0x012ff7b7 coh
		553	0x28cd3d45 cramfs
		554	0x453dcd28 cramfs-wend (wrong endianness)
		555	0x64626720 debugfs
		556	0x00001373 devfs
		557	0x00001cd1 devpts
		558	0x0000f15f ecryptfs
		559	0x00414a53 efs
		560	0x0000137d ext
		561	0x0000ef53 ext2/ext3/ext4
		562	0x0000ef51 ext2
		563	0xf2f52010 f2fs
		564	0x00004006 fat
		565	0x65735546 fuseblk
		566	0x65735543 fusectl
		567	0x0bad1dea futexfs
		568	0x01161970 gfs2
		569	0x47504653 gpfs
		570	0x00004244 hfs
		571	0xf995e849 hpfs
		572	0x00c0ffee hostfs
		573	0x958458f6 hugetlbfs
		574	0x2bad1dea inotifyfs
		575	0x00009660 isofs
		576	0x000072b6 jffs2
		577	0x3153464a jfs
		578	0x6b414653 k-afs
		579	0x0bd00bd0 lustre
		580	0x0000137f minix
		581	0x0000138f minix 30 char names
		582	0x00002468 minix v2
		583	0x00002478 minix v2 30 char names
		584	0x00004d5a minix v3
		585	0x19800202 mqueue
		586	0x00004d44 msdos
		587	0x0000564c novell
		588	0x00006969 nfs
		589	0x6e667364 nfsd
		590	0x00003434 nilfs
		591	0x5346544e ntfs
		592	0x00009fa1 openprom
		593	0x7461636F ocfs2
		594	0x00009fa0 proc
		595	0x6165676c pstorefs
		596	0x0000002f qnx4
		597	0x68191122 qnx6
		598	0x858458f6 ramfs
		599	0x52654973 reiserfs
		600	0x00007275 romfs
		601	0x67596969 rpc_pipefs
		602	0x73636673 securityfs
		603	0xf97cff8c selinux
		604	0x0000517b smb
		605	0x534f434b sockfs
		606	0x73717368 squashfs
		607	0x62656572 sysfs
		608	0x012ff7b6 sysv2
		609	0x012ff7b5 sysv4
		610	0x01021994 tmpfs
		611	0x15013346 udf
		612	0x00011954 ufs
		613	0x54190100 ufs byteswapped
		614	0x00009fa2 usbdevfs
		615	0x01021997 v9fs
		616	0xa501fcf5 vxfs
		617	0xabba1974 xenfs
		618	0x012ff7b4 xenix
		619	0x58465342 xfs
		620	0x012fd16d xia
		621
455	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)	622	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
456	Works like perl's "utime" function (including the special case of	623	Works like perl's "utime" function (including the special case of
457	$atime and $mtime being undef). Fractional times are supported if	624	$atime and $mtime being undef). Fractional times are supported if
458	the underlying syscalls support them.	625	the underlying syscalls support them.
459		626
…		…
481	aio_chown "path", 0, undef;	648	aio_chown "path", 0, undef;
482		649
483	aio_truncate $fh_or_path, $offset, $callback->($status)	650	aio_truncate $fh_or_path, $offset, $callback->($status)
484	Works like truncate(2) or ftruncate(2).	651	Works like truncate(2) or ftruncate(2).
485		652
		653	aio_allocate $fh, $mode, $offset, $len, $callback->($status)
		654	Allocates or frees disk space according to the $mode argument. See
		655	the linux "fallocate" documentation for details.
		656
		657	$mode is usually 0 or "IO::AIO::FALLOC_FL_KEEP_SIZE" to allocate
		658	space, or "IO::AIO::FALLOC_FL_PUNCH_HOLE \|
		659	IO::AIO::FALLOC_FL_KEEP_SIZE", to deallocate a file range.
		660
		661	IO::AIO also supports "FALLOC_FL_COLLAPSE_RANGE", to remove a range
		662	(without leaving a hole) and "FALLOC_FL_ZERO_RANGE", to zero a range
		663	(see your fallocate(2) manpage).
		664
		665	The file system block size used by "fallocate" is presumably the
		666	"f_bsize" returned by "statvfs".
		667
		668	If "fallocate" isn't available or cannot be emulated (currently no
		669	emulation will be attempted), passes -1 and sets $! to "ENOSYS".
		670
486	aio_chmod $fh_or_path, $mode, $callback->($status)	671	aio_chmod $fh_or_path, $mode, $callback->($status)
487	Works like perl's "chmod" function.	672	Works like perl's "chmod" function.
488		673
489	aio_unlink $pathname, $callback->($status)	674	aio_unlink $pathname, $callback->($status)
490	Asynchronously unlink (delete) a file and call the callback with the	675	Asynchronously unlink (delete) a file and call the callback with the
491	result code.	676	result code.
492		677
493	aio_mknod $path, $mode, $dev, $callback->($status)	678	aio_mknod $pathname, $mode, $dev, $callback->($status)
494	[EXPERIMENTAL]	679	[EXPERIMENTAL]
495		680
496	Asynchronously create a device node (or fifo). See mknod(2).	681	Asynchronously create a device node (or fifo). See mknod(2).
497		682
498	The only (POSIX-) portable way of calling this function is:	683	The only (POSIX-) portable way of calling this function is:
499		684
500	aio_mknod $path, IO::AIO::S_IFIFO \| $mode, 0, sub { ...	685	aio_mknod $pathname, IO::AIO::S_IFIFO \| $mode, 0, sub { ...
		686
		687	See "aio_stat" for info about some potentially helpful extra
		688	constants and functions.
501		689
502	aio_link $srcpath, $dstpath, $callback->($status)	690	aio_link $srcpath, $dstpath, $callback->($status)
503	Asynchronously create a new link to the existing object at $srcpath	691	Asynchronously create a new link to the existing object at $srcpath
504	at the path $dstpath and call the callback with the result code.	692	at the path $dstpath and call the callback with the result code.
505		693
506	aio_symlink $srcpath, $dstpath, $callback->($status)	694	aio_symlink $srcpath, $dstpath, $callback->($status)
507	Asynchronously create a new symbolic link to the existing object at	695	Asynchronously create a new symbolic link to the existing object at
508	$srcpath at the path $dstpath and call the callback with the result	696	$srcpath at the path $dstpath and call the callback with the result
509	code.	697	code.
510		698
511	aio_readlink $path, $callback->($link)	699	aio_readlink $pathname, $callback->($link)
512	Asynchronously read the symlink specified by $path and pass it to	700	Asynchronously read the symlink specified by $path and pass it to
513	the callback. If an error occurs, nothing or undef gets passed to	701	the callback. If an error occurs, nothing or undef gets passed to
514	the callback.	702	the callback.
515		703
		704	aio_realpath $pathname, $callback->($path)
		705	Asynchronously make the path absolute and resolve any symlinks in
		706	$path. The resulting path only consists of directories (same as
		707	Cwd::realpath).
		708
		709	This request can be used to get the absolute path of the current
		710	working directory by passing it a path of . (a single dot).
		711
516	aio_rename $srcpath, $dstpath, $callback->($status)	712	aio_rename $srcpath, $dstpath, $callback->($status)
517	Asynchronously rename the object at $srcpath to $dstpath, just as	713	Asynchronously rename the object at $srcpath to $dstpath, just as
518	rename(2) and call the callback with the result code.	714	rename(2) and call the callback with the result code.
		715
		716	On systems that support the AIO::WD working directory abstraction
		717	natively, the case "[$wd, "."]" as $srcpath is specialcased -
		718	instead of failing, "rename" is called on the absolute path of $wd.
519		719
520	aio_mkdir $pathname, $mode, $callback->($status)	720	aio_mkdir $pathname, $mode, $callback->($status)
521	Asynchronously mkdir (create) a directory and call the callback with	721	Asynchronously mkdir (create) a directory and call the callback with
522	the result code. $mode will be modified by the umask at the time the	722	the result code. $mode will be modified by the umask at the time the
523	request is executed, so do not change your umask.	723	request is executed, so do not change your umask.
524		724
525	aio_rmdir $pathname, $callback->($status)	725	aio_rmdir $pathname, $callback->($status)
526	Asynchronously rmdir (delete) a directory and call the callback with	726	Asynchronously rmdir (delete) a directory and call the callback with
527	the result code.	727	the result code.
528		728
		729	On systems that support the AIO::WD working directory abstraction
		730	natively, the case "[$wd, "."]" is specialcased - instead of
		731	failing, "rmdir" is called on the absolute path of $wd.
		732
529	aio_readdir $pathname, $callback->($entries)	733	aio_readdir $pathname, $callback->($entries)
530	Unlike the POSIX call of the same name, "aio_readdir" reads an	734	Unlike the POSIX call of the same name, "aio_readdir" reads an
531	entire directory (i.e. opendir + readdir + closedir). The entries	735	entire directory (i.e. opendir + readdir + closedir). The entries
532	will not be sorted, and will NOT include the "." and ".." entries.	736	will not be sorted, and will NOT include the "." and ".." entries.
533		737
534	The callback is passed a single argument which is either "undef" or	738	The callback is passed a single argument which is either "undef" or
535	an array-ref with the filenames.	739	an array-ref with the filenames.
536		740
537	aio_readdirx $pathname, $flags, $callback->($entries, $flags)	741	aio_readdirx $pathname, $flags, $callback->($entries, $flags)
538	Quite similar to "aio_readdir", but the $flags argument allows to	742	Quite similar to "aio_readdir", but the $flags argument allows one
539	tune behaviour and output format. In case of an error, $entries will	743	to tune behaviour and output format. In case of an error, $entries
540	be "undef".	744	will be "undef".
541		745
542	The flags are a combination of the following constants, ORed	746	The flags are a combination of the following constants, ORed
543	together (the flags will also be passed to the callback, possibly	747	together (the flags will also be passed to the callback, possibly
544	modified):	748	modified):
545		749
546	IO::AIO::READDIR_DENTS	750	IO::AIO::READDIR_DENTS
547	When this flag is off, then the callback gets an arrayref with	751	When this flag is off, then the callback gets an arrayref
548	of names only (as with "aio_readdir"), otherwise it gets an	752	consisting of names only (as with "aio_readdir"), otherwise it
549	arrayref with "[$name, $type, $inode]" arrayrefs, each	753	gets an arrayref with "[$name, $type, $inode]" arrayrefs, each
550	describing a single directory entry in more detail.	754	describing a single directory entry in more detail.
551		755
552	$name is the name of the entry.	756	$name is the name of the entry.
553		757
554	$type is one of the "IO::AIO::DT_xxx" constants:	758	$type is one of the "IO::AIO::DT_xxx" constants:
…		…
567	unspecified content on systems that do not deliver the inode	771	unspecified content on systems that do not deliver the inode
568	information.	772	information.
569		773
570	IO::AIO::READDIR_DIRS_FIRST	774	IO::AIO::READDIR_DIRS_FIRST
571	When this flag is set, then the names will be returned in an	775	When this flag is set, then the names will be returned in an
572	order where likely directories come first. This is useful when	776	order where likely directories come first, in optimal stat
573	you need to quickly find directories, or you want to find all	777	order. This is useful when you need to quickly find directories,
574	directories while avoiding to stat() each entry.	778	or you want to find all directories while avoiding to stat()
		779	each entry.
575		780
576	If the system returns type information in readdir, then this is	781	If the system returns type information in readdir, then this is
577	used to find directories directly. Otherwise, likely directories	782	used to find directories directly. Otherwise, likely directories
578	are files beginning with ".", or otherwise files with no dots,	783	are names beginning with ".", or otherwise names with no dots,
579	of which files with short names are tried first.	784	of which names with short names are tried first.
580		785
581	IO::AIO::READDIR_STAT_ORDER	786	IO::AIO::READDIR_STAT_ORDER
582	When this flag is set, then the names will be returned in an	787	When this flag is set, then the names will be returned in an
583	order suitable for stat()'ing each one. That is, when you plan	788	order suitable for stat()'ing each one. That is, when you plan
584	to stat() all files in the given directory, then the returned	789	to stat() all files in the given directory, then the returned
…		…
589	optimal stat order.	794	optimal stat order.
590		795
591	IO::AIO::READDIR_FOUND_UNKNOWN	796	IO::AIO::READDIR_FOUND_UNKNOWN
592	This flag should not be set when calling "aio_readdirx".	797	This flag should not be set when calling "aio_readdirx".
593	Instead, it is being set by "aio_readdirx", when any of the	798	Instead, it is being set by "aio_readdirx", when any of the
594	$type's found were "IO::AIO::DT_UNKNOWN". The absense of this	799	$type's found were "IO::AIO::DT_UNKNOWN". The absence of this
595	flag therefore indicates that all $type's are known, which can	800	flag therefore indicates that all $type's are known, which can
596	be used to speed up some algorithms.	801	be used to speed up some algorithms.
597		802
598	aio_load $path, $data, $callback->($status)	803	aio_load $pathname, $data, $callback->($status)
599	This is a composite request that tries to fully load the given file	804	This is a composite request that tries to fully load the given file
600	into memory. Status is the same as with aio_read.	805	into memory. Status is the same as with aio_read.
601		806
602	aio_copy $srcpath, $dstpath, $callback->($status)	807	aio_copy $srcpath, $dstpath, $callback->($status)
603	Try to copy the file (directories not supported as either source	808	Try to copy the file (directories not supported as either source
…		…
620		825
621	This is a composite request that tries to rename(2) the file first;	826	This is a composite request that tries to rename(2) the file first;
622	if rename fails with "EXDEV", it copies the file with "aio_copy"	827	if rename fails with "EXDEV", it copies the file with "aio_copy"
623	and, if that is successful, unlinks the $srcpath.	828	and, if that is successful, unlinks the $srcpath.
624		829
625	aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	830	aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
626	Scans a directory (similar to "aio_readdir") but additionally tries	831	Scans a directory (similar to "aio_readdir") but additionally tries
627	to efficiently separate the entries of directory $path into two sets	832	to efficiently separate the entries of directory $path into two sets
628	of names, directories you can recurse into (directories), and ones	833	of names, directories you can recurse into (directories), and ones
629	you cannot recurse into (everything else, including symlinks to	834	you cannot recurse into (everything else, including symlinks to
630	directories).	835	directories).
…		…
663	Then entries will be sorted into likely directories a non-initial	868	Then entries will be sorted into likely directories a non-initial
664	dot currently) and likely non-directories (see "aio_readdirx"). Then	869	dot currently) and likely non-directories (see "aio_readdirx"). Then
665	every entry plus an appended "/." will be "stat"'ed, likely	870	every entry plus an appended "/." will be "stat"'ed, likely
666	directories first, in order of their inode numbers. If that	871	directories first, in order of their inode numbers. If that
667	succeeds, it assumes that the entry is a directory or a symlink to	872	succeeds, it assumes that the entry is a directory or a symlink to
668	directory (which will be checked seperately). This is often faster	873	directory (which will be checked separately). This is often faster
669	than stat'ing the entry itself because filesystems might detect the	874	than stat'ing the entry itself because filesystems might detect the
670	type of the entry without reading the inode data (e.g. ext2fs	875	type of the entry without reading the inode data (e.g. ext2fs
671	filetype feature), even on systems that cannot return the filetype	876	filetype feature), even on systems that cannot return the filetype
672	information on readdir.	877	information on readdir.
673		878
…		…
679		884
680	It will also likely work on non-POSIX filesystems with reduced	885	It will also likely work on non-POSIX filesystems with reduced
681	efficiency as those tend to return 0 or 1 as link counts, which	886	efficiency as those tend to return 0 or 1 as link counts, which
682	disables the directory counting heuristic.	887	disables the directory counting heuristic.
683		888
684	aio_rmtree $path, $callback->($status)	889	aio_rmtree $pathname, $callback->($status)
685	Delete a directory tree starting (and including) $path, return the	890	Delete a directory tree starting (and including) $path, return the
686	status of the final "rmdir" only. This is a composite request that	891	status of the final "rmdir" only. This is a composite request that
687	uses "aio_scandir" to recurse into and rmdir directories, and unlink	892	uses "aio_scandir" to recurse into and rmdir directories, and unlink
688	everything else.	893	everything else.
689		894
		895	aio_fcntl $fh, $cmd, $arg, $callback->($status)
		896	aio_ioctl $fh, $request, $buf, $callback->($status)
		897	These work just like the "fcntl" and "ioctl" built-in functions,
		898	except they execute asynchronously and pass the return value to the
		899	callback.
		900
		901	Both calls can be used for a lot of things, some of which make more
		902	sense to run asynchronously in their own thread, while some others
		903	make less sense. For example, calls that block waiting for external
		904	events, such as locking, will also lock down an I/O thread while it
		905	is waiting, which can deadlock the whole I/O system. At the same
		906	time, there might be no alternative to using a thread to wait.
		907
		908	So in general, you should only use these calls for things that do
		909	(filesystem) I/O, not for things that wait for other events
		910	(network, other processes), although if you are careful and know
		911	what you are doing, you still can.
		912
690	aio_sync $callback->($status)	913	aio_sync $callback->($status)
691	Asynchronously call sync and call the callback when finished.	914	Asynchronously call sync and call the callback when finished.
692		915
693	aio_fsync $fh, $callback->($status)	916	aio_fsync $fh, $callback->($status)
694	Asynchronously call fsync on the given filehandle and call the	917	Asynchronously call fsync on the given filehandle and call the
…		…
698	Asynchronously call fdatasync on the given filehandle and call the	921	Asynchronously call fdatasync on the given filehandle and call the
699	callback with the fdatasync result code.	922	callback with the fdatasync result code.
700		923
701	If this call isn't available because your OS lacks it or it couldn't	924	If this call isn't available because your OS lacks it or it couldn't
702	be detected, it will be emulated by calling "fsync" instead.	925	be detected, it will be emulated by calling "fsync" instead.
		926
		927	aio_syncfs $fh, $callback->($status)
		928	Asynchronously call the syncfs syscall to sync the filesystem
		929	associated to the given filehandle and call the callback with the
		930	syncfs result code. If syncfs is not available, calls sync(), but
		931	returns -1 and sets errno to "ENOSYS" nevertheless.
703		932
704	aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)	933	aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
705	Sync the data portion of the file specified by $offset and $length	934	Sync the data portion of the file specified by $offset and $length
706	to disk (but NOT the metadata), by calling the Linux-specific	935	to disk (but NOT the metadata), by calling the Linux-specific
707	sync_file_range call. If sync_file_range is not available or it	936	sync_file_range call. If sync_file_range is not available or it
…		…
711	"IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE",	940	"IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE",
712	"IO::AIO::SYNC_FILE_RANGE_WRITE" and	941	"IO::AIO::SYNC_FILE_RANGE_WRITE" and
713	"IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER": refer to the sync_file_range	942	"IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER": refer to the sync_file_range
714	manpage for details.	943	manpage for details.
715		944
716	aio_pathsync $path, $callback->($status)	945	aio_pathsync $pathname, $callback->($status)
717	This request tries to open, fsync and close the given path. This is	946	This request tries to open, fsync and close the given path. This is
718	a composite request intended to sync directories after directory	947	a composite request intended to sync directories after directory
719	operations (E.g. rename). This might not work on all operating	948	operations (E.g. rename). This might not work on all operating
720	systems or have any specific effect, but usually it makes sure that	949	systems or have any specific effect, but usually it makes sure that
721	directory changes get written to disc. It works for anything that	950	directory changes get written to disc. It works for anything that
…		…
748		977
749	It touches (reads or writes) all memory pages in the specified range	978	It touches (reads or writes) all memory pages in the specified range
750	inside the scalar. All caveats and parameters are the same as for	979	inside the scalar. All caveats and parameters are the same as for
751	"aio_msync", above, except for flags, which must be either 0 (which	980	"aio_msync", above, except for flags, which must be either 0 (which
752	reads all pages and ensures they are instantiated) or	981	reads all pages and ensures they are instantiated) or
753	"IO::AIO::MT_MODIFY", which modifies the memory page s(by reading	982	"IO::AIO::MT_MODIFY", which modifies the memory pages (by reading
754	and writing an octet from it, which dirties the page).	983	and writing an octet from it, which dirties the page).
		984
		985	aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
		986	This is a rather advanced IO::AIO call, which works best on
		987	mmap(2)ed scalars.
		988
		989	It reads in all the pages of the underlying storage into memory (if
		990	any) and locks them, so they are not getting swapped/paged out or
		991	removed.
		992
		993	If $length is undefined, then the scalar will be locked till the
		994	end.
		995
		996	On systems that do not implement "mlock", this function returns -1
		997	and sets errno to "ENOSYS".
		998
		999	Note that the corresponding "munlock" is synchronous and is
		1000	documented under "MISCELLANEOUS FUNCTIONS".
		1001
		1002	Example: open a file, mmap and mlock it - both will be undone when
		1003	$data gets destroyed.
		1004
		1005	open my $fh, "<", $path or die "$path: $!";
		1006	my $data;
		1007	IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;
		1008	aio_mlock $data; # mlock in background
		1009
		1010	aio_mlockall $flags, $callback->($status)
		1011	Calls the "mlockall" function with the given $flags (a combination
		1012	of "IO::AIO::MCL_CURRENT" and "IO::AIO::MCL_FUTURE").
		1013
		1014	On systems that do not implement "mlockall", this function returns
		1015	-1 and sets errno to "ENOSYS".
		1016
		1017	Note that the corresponding "munlockall" is synchronous and is
		1018	documented under "MISCELLANEOUS FUNCTIONS".
		1019
		1020	Example: asynchronously lock all current and future pages into
		1021	memory.
		1022
		1023	aio_mlockall IO::AIO::MCL_FUTURE;
		1024
		1025	aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
		1026	Queries the extents of the given file (by calling the Linux "FIEMAP"
		1027	ioctl, see <http://cvs.schmorp.de/IO-AIO/doc/fiemap.txt> for
		1028	details). If the ioctl is not available on your OS, then this
		1029	request will fail with "ENOSYS".
		1030
		1031	$start is the starting offset to query extents for, $length is the
		1032	size of the range to query - if it is "undef", then the whole file
		1033	will be queried.
		1034
		1035	$flags is a combination of flags ("IO::AIO::FIEMAP_FLAG_SYNC" or
		1036	"IO::AIO::FIEMAP_FLAG_XATTR" - "IO::AIO::FIEMAP_FLAGS_COMPAT" is
		1037	also exported), and is normally 0 or "IO::AIO::FIEMAP_FLAG_SYNC" to
		1038	query the data portion.
		1039
		1040	$count is the maximum number of extent records to return. If it is
		1041	"undef", then IO::AIO queries all extents of the range. As a very
		1042	special case, if it is 0, then the callback receives the number of
		1043	extents instead of the extents themselves (which is unreliable, see
		1044	below).
		1045
		1046	If an error occurs, the callback receives no arguments. The special
		1047	"errno" value "IO::AIO::EBADR" is available to test for flag errors.
		1048
		1049	Otherwise, the callback receives an array reference with extent
		1050	structures. Each extent structure is an array reference itself, with
		1051	the following members:
		1052
		1053	[$logical, $physical, $length, $flags]
		1054
		1055	Flags is any combination of the following flag values (typically
		1056	either 0 or "IO::AIO::FIEMAP_EXTENT_LAST" (1)):
		1057
		1058	"IO::AIO::FIEMAP_EXTENT_LAST", "IO::AIO::FIEMAP_EXTENT_UNKNOWN",
		1059	"IO::AIO::FIEMAP_EXTENT_DELALLOC", "IO::AIO::FIEMAP_EXTENT_ENCODED",
		1060	"IO::AIO::FIEMAP_EXTENT_DATA_ENCRYPTED",
		1061	"IO::AIO::FIEMAP_EXTENT_NOT_ALIGNED",
		1062	"IO::AIO::FIEMAP_EXTENT_DATA_INLINE",
		1063	"IO::AIO::FIEMAP_EXTENT_DATA_TAIL",
		1064	"IO::AIO::FIEMAP_EXTENT_UNWRITTEN", "IO::AIO::FIEMAP_EXTENT_MERGED"
		1065	or "IO::AIO::FIEMAP_EXTENT_SHARED".
		1066
		1067	At the time of this writing (Linux 3.2), this requets is unreliable
		1068	unless $count is "undef", as the kernel has all sorts of bugs
		1069	preventing it to return all extents of a range for files with large
		1070	number of extents. The code works around all these issues if $count
		1071	is undef.
755		1072
756	aio_group $callback->(...)	1073	aio_group $callback->(...)
757	This is a very special aio request: Instead of doing something, it	1074	This is a very special aio request: Instead of doing something, it
758	is a container for other aio requests, which is useful if you want	1075	is a container for other aio requests, which is useful if you want
759	to bundle many requests into a single, composite, request with a	1076	to bundle many requests into a single, composite, request with a
…		…
793	While it is theoretically handy to have simple I/O scheduling	1110	While it is theoretically handy to have simple I/O scheduling
794	requests like sleep and file handle readable/writable, the overhead	1111	requests like sleep and file handle readable/writable, the overhead
795	this creates is immense (it blocks a thread for a long time) so do	1112	this creates is immense (it blocks a thread for a long time) so do
796	not use this function except to put your application under	1113	not use this function except to put your application under
797	artificial I/O pressure.	1114	artificial I/O pressure.
		1115
		1116	IO::AIO::WD - multiple working directories
		1117	Your process only has one current working directory, which is used by
		1118	all threads. This makes it hard to use relative paths (some other
		1119	component could call "chdir" at any time, and it is hard to control when
		1120	the path will be used by IO::AIO).
		1121
		1122	One solution for this is to always use absolute paths. This usually
		1123	works, but can be quite slow (the kernel has to walk the whole path on
		1124	every access), and can also be a hassle to implement.
		1125
		1126	Newer POSIX systems have a number of functions (openat, fdopendir,
		1127	futimensat and so on) that make it possible to specify working
		1128	directories per operation.
		1129
		1130	For portability, and because the clowns who "designed", or shall I
		1131	write, perpetrated this new interface were obviously half-drunk, this
		1132	abstraction cannot be perfect, though.
		1133
		1134	IO::AIO allows you to convert directory paths into a so-called
		1135	IO::AIO::WD object. This object stores the canonicalised, absolute
		1136	version of the path, and on systems that allow it, also a directory file
		1137	descriptor.
		1138
		1139	Everywhere where a pathname is accepted by IO::AIO (e.g. in "aio_stat"
		1140	or "aio_unlink"), one can specify an array reference with an IO::AIO::WD
		1141	object and a pathname instead (or the IO::AIO::WD object alone, which
		1142	gets interpreted as "[$wd, "."]"). If the pathname is absolute, the
		1143	IO::AIO::WD object is ignored, otherwise the pathname is resolved
		1144	relative to that IO::AIO::WD object.
		1145
		1146	For example, to get a wd object for /etc and then stat passwd inside,
		1147	you would write:
		1148
		1149	aio_wd "/etc", sub {
		1150	my $etcdir = shift;
		1151
		1152	# although $etcdir can be undef on error, there is generally no reason
		1153	# to check for errors here, as aio_stat will fail with ENOENT
		1154	# when $etcdir is undef.
		1155
		1156	aio_stat [$etcdir, "passwd"], sub {
		1157	# yay
		1158	};
		1159	};
		1160
		1161	The fact that "aio_wd" is a request and not a normal function shows that
		1162	creating an IO::AIO::WD object is itself a potentially blocking
		1163	operation, which is why it is done asynchronously.
		1164
		1165	To stat the directory obtained with "aio_wd" above, one could write
		1166	either of the following three request calls:
		1167
		1168	aio_lstat "/etc" , sub { ... # pathname as normal string
		1169	aio_lstat [$wd, "."], sub { ... # "." relative to $wd (i.e. $wd itself)
		1170	aio_lstat $wd , sub { ... # shorthand for the previous
		1171
		1172	As with normal pathnames, IO::AIO keeps a copy of the working directory
		1173	object and the pathname string, so you could write the following without
		1174	causing any issues due to $path getting reused:
		1175
		1176	my $path = [$wd, undef];
		1177
		1178	for my $name (qw(abc def ghi)) {
		1179	$path->[1] = $name;
		1180	aio_stat $path, sub {
		1181	# ...
		1182	};
		1183	}
		1184
		1185	There are some caveats: when directories get renamed (or deleted), the
		1186	pathname string doesn't change, so will point to the new directory (or
		1187	nowhere at all), while the directory fd, if available on the system,
		1188	will still point to the original directory. Most functions accepting a
		1189	pathname will use the directory fd on newer systems, and the string on
		1190	older systems. Some functions (such as realpath) will always rely on the
		1191	string form of the pathname.
		1192
		1193	So this functionality is mainly useful to get some protection against
		1194	"chdir", to easily get an absolute path out of a relative path for
		1195	future reference, and to speed up doing many operations in the same
		1196	directory (e.g. when stat'ing all files in a directory).
		1197
		1198	The following functions implement this working directory abstraction:
		1199
		1200	aio_wd $pathname, $callback->($wd)
		1201	Asynchonously canonicalise the given pathname and convert it to an
		1202	IO::AIO::WD object representing it. If possible and supported on the
		1203	system, also open a directory fd to speed up pathname resolution
		1204	relative to this working directory.
		1205
		1206	If something goes wrong, then "undef" is passwd to the callback
		1207	instead of a working directory object and $! is set appropriately.
		1208	Since passing "undef" as working directory component of a pathname
		1209	fails the request with "ENOENT", there is often no need for error
		1210	checking in the "aio_wd" callback, as future requests using the
		1211	value will fail in the expected way.
		1212
		1213	IO::AIO::CWD
		1214	This is a compiletime constant (object) that represents the process
		1215	current working directory.
		1216
		1217	Specifying this object as working directory object for a pathname is
		1218	as if the pathname would be specified directly, without a directory
		1219	object. For example, these calls are functionally identical:
		1220
		1221	aio_stat "somefile", sub { ... };
		1222	aio_stat [IO::AIO::CWD, "somefile"], sub { ... };
		1223
		1224	To recover the path associated with an IO::AIO::WD object, you can use
		1225	"aio_realpath":
		1226
		1227	aio_realpath $wd, sub {
		1228	warn "path is $_[0]\n";
		1229	};
		1230
		1231	Currently, "aio_statvfs" always, and "aio_rename" and "aio_rmdir"
		1232	sometimes, fall back to using an absolue path.
798		1233
799	IO::AIO::REQ CLASS	1234	IO::AIO::REQ CLASS
800	All non-aggregate "aio_*" functions return an object of this class when	1235	All non-aggregate "aio_*" functions return an object of this class when
801	called in non-void context.	1236	called in non-void context.
802		1237
…		…
902	Sets a feeder/generator on this group: every group can have an	1337	Sets a feeder/generator on this group: every group can have an
903	attached generator that generates requests if idle. The idea behind	1338	attached generator that generates requests if idle. The idea behind
904	this is that, although you could just queue as many requests as you	1339	this is that, although you could just queue as many requests as you
905	want in a group, this might starve other requests for a potentially	1340	want in a group, this might starve other requests for a potentially
906	long time. For example, "aio_scandir" might generate hundreds of	1341	long time. For example, "aio_scandir" might generate hundreds of
907	thousands "aio_stat" requests, delaying any later requests for a	1342	thousands of "aio_stat" requests, delaying any later requests for a
908	long time.	1343	long time.
909		1344
910	To avoid this, and allow incremental generation of requests, you can	1345	To avoid this, and allow incremental generation of requests, you can
911	instead a group and set a feeder on it that generates those	1346	instead a group and set a feeder on it that generates those
912	requests. The feed callback will be called whenever there are few	1347	requests. The feed callback will be called whenever there are few
…		…
954	results.	1389	results.
955		1390
956	See "poll_cb" for an example.	1391	See "poll_cb" for an example.
957		1392
958	IO::AIO::poll_cb	1393	IO::AIO::poll_cb
959	Process some outstanding events on the result pipe. You have to call	1394	Process some requests that have reached the result phase (i.e. they
960	this regularly. Returns 0 if all events could be processed, or -1 if	1395	have been executed but the results are not yet reported). You have
961	it returned earlier for whatever reason. Returns immediately when no	1396	to call this "regularly" to finish outstanding requests.
962	events are outstanding. The amount of events processed depends on
963	the settings of "IO::AIO::max_poll_req" and
964	"IO::AIO::max_poll_time".
965		1397
		1398	Returns 0 if all events could be processed (or there were no events
		1399	to process), or -1 if it returned earlier for whatever reason.
		1400	Returns immediately when no events are outstanding. The amount of
		1401	events processed depends on the settings of "IO::AIO::max_poll_req",
		1402	"IO::AIO::max_poll_time" and "IO::AIO::max_outstanding".
		1403
966	If not all requests were processed for whatever reason, the	1404	If not all requests were processed for whatever reason, the poll
967	filehandle will still be ready when "poll_cb" returns, so normally	1405	file descriptor will still be ready when "poll_cb" returns, so
968	you don't have to do anything special to have it called later.	1406	normally you don't have to do anything special to have it called
		1407	later.
		1408
		1409	Apart from calling "IO::AIO::poll_cb" when the event filehandle
		1410	becomes ready, it can be beneficial to call this function from loops
		1411	which submit a lot of requests, to make sure the results get
		1412	processed when they become available and not just when the loop is
		1413	finished and the event loop takes over again. This function returns
		1414	very fast when there are no outstanding requests.
969		1415
970	Example: Install an Event watcher that automatically calls	1416	Example: Install an Event watcher that automatically calls
971	IO::AIO::poll_cb with high priority (more examples can be found in	1417	IO::AIO::poll_cb with high priority (more examples can be found in
972	the SYNOPSIS section, at the top of this document):	1418	the SYNOPSIS section, at the top of this document):
973		1419
974	Event->io (fd => IO::AIO::poll_fileno,	1420	Event->io (fd => IO::AIO::poll_fileno,
975	poll => 'r', async => 1,	1421	poll => 'r', async => 1,
976	cb => \&IO::AIO::poll_cb);	1422	cb => \&IO::AIO::poll_cb);
977		1423
978	IO::AIO::poll_wait	1424	IO::AIO::poll_wait
979	If there are any outstanding requests and none of them in the result	1425	Wait until either at least one request is in the result phase or no
980	phase, wait till the result filehandle becomes ready for reading	1426	requests are outstanding anymore.
981	(simply does a "select" on the filehandle. This is useful if you	1427
982	want to synchronously wait for some requests to finish).	1428	This is useful if you want to synchronously wait for some requests
		1429	to become ready, without actually handling them.
983		1430
984	See "nreqs" for an example.	1431	See "nreqs" for an example.
985		1432
986	IO::AIO::poll	1433	IO::AIO::poll
987	Waits until some requests have been handled.	1434	Waits until some requests have been handled.
…		…
1067		1514
1068	Under normal circumstances you don't need to call this function.	1515	Under normal circumstances you don't need to call this function.
1069		1516
1070	IO::AIO::max_idle $nthreads	1517	IO::AIO::max_idle $nthreads
1071	Limit the number of threads (default: 4) that are allowed to idle	1518	Limit the number of threads (default: 4) that are allowed to idle
1072	(i.e., threads that did not get a request to process within 10	1519	(i.e., threads that did not get a request to process within the idle
1073	seconds). That means if a thread becomes idle while $nthreads other	1520	timeout (default: 10 seconds). That means if a thread becomes idle
1074	threads are also idle, it will free its resources and exit.	1521	while $nthreads other threads are also idle, it will free its
		1522	resources and exit.
1075		1523
1076	This is useful when you allow a large number of threads (e.g. 100 or	1524	This is useful when you allow a large number of threads (e.g. 100 or
1077	1000) to allow for extremely high load situations, but want to free	1525	1000) to allow for extremely high load situations, but want to free
1078	resources under normal circumstances (1000 threads can easily	1526	resources under normal circumstances (1000 threads can easily
1079	consume 30MB of RAM).	1527	consume 30MB of RAM).
1080		1528
1081	The default is probably ok in most situations, especially if thread	1529	The default is probably ok in most situations, especially if thread
1082	creation is fast. If thread creation is very slow on your system you	1530	creation is fast. If thread creation is very slow on your system you
1083	might want to use larger values.	1531	might want to use larger values.
1084		1532
		1533	IO::AIO::idle_timeout $seconds
		1534	Sets the minimum idle timeout (default 10) after which worker
		1535	threads are allowed to exit. SEe "IO::AIO::max_idle".
		1536
1085	IO::AIO::max_outstanding $maxreqs	1537	IO::AIO::max_outstanding $maxreqs
		1538	Sets the maximum number of outstanding requests to $nreqs. If you do
		1539	queue up more than this number of requests, the next call to
		1540	"IO::AIO::poll_cb" (and other functions calling "poll_cb", such as
		1541	"IO::AIO::flush" or "IO::AIO::poll") will block until the limit is
		1542	no longer exceeded.
		1543
		1544	In other words, this setting does not enforce a queue limit, but can
		1545	be used to make poll functions block if the limit is exceeded.
		1546
1086	This is a very bad function to use in interactive programs because	1547	This is a very bad function to use in interactive programs because
1087	it blocks, and a bad way to reduce concurrency because it is	1548	it blocks, and a bad way to reduce concurrency because it is
1088	inexact: Better use an "aio_group" together with a feed callback.	1549	inexact: Better use an "aio_group" together with a feed callback.
1089		1550
1090	Sets the maximum number of outstanding requests to $nreqs. If you do	1551	Its main use is in scripts without an event loop - when you want to
1091	queue up more than this number of requests, the next call to the	1552	stat a lot of files, you can write somehting like this:
1092	"poll_cb" (and "poll_some" and other functions calling "poll_cb")
1093	function will block until the limit is no longer exceeded.
1094		1553
1095	The default value is very large, so there is no practical limit on	1554	IO::AIO::max_outstanding 32;
		1555
		1556	for my $path (...) {
		1557	aio_stat $path , ...;
		1558	IO::AIO::poll_cb;
		1559	}
		1560
		1561	IO::AIO::flush;
		1562
		1563	The call to "poll_cb" inside the loop will normally return
		1564	instantly, but as soon as more thna 32 reqeusts are in-flight, it
		1565	will block until some requests have been handled. This keeps the
		1566	loop from pushing a large number of "aio_stat" requests onto the
		1567	queue.
		1568
		1569	The default value for "max_outstanding" is very large, so there is
1096	the number of outstanding requests.	1570	no practical limit on the number of outstanding requests.
1097
1098	You can still queue as many requests as you want. Therefore,
1099	"max_outstanding" is mainly useful in simple scripts (with low
1100	values) or as a stop gap to shield against fatal memory overflow
1101	(with large values).
1102		1571
1103	STATISTICAL INFORMATION	1572	STATISTICAL INFORMATION
1104	IO::AIO::nreqs	1573	IO::AIO::nreqs
1105	Returns the number of requests currently in the ready, execute or	1574	Returns the number of requests currently in the ready, execute or
1106	pending states (i.e. for which their callback has not been invoked	1575	pending states (i.e. for which their callback has not been invoked
…		…
1118	IO::AIO::npending	1587	IO::AIO::npending
1119	Returns the number of requests currently in the pending state	1588	Returns the number of requests currently in the pending state
1120	(executed, but not yet processed by poll_cb).	1589	(executed, but not yet processed by poll_cb).
1121		1590
1122	MISCELLANEOUS FUNCTIONS	1591	MISCELLANEOUS FUNCTIONS
1123	IO::AIO implements some functions that might be useful, but are not	1592	IO::AIO implements some functions that are useful when you want to use
1124	asynchronous.	1593	some "Advanced I/O" function not available to in Perl, without going the
		1594	"Asynchronous I/O" route. Many of these have an asynchronous "aio_*"
		1595	counterpart.
1125		1596
1126	IO::AIO::sendfile $ofh, $ifh, $offset, $count	1597	IO::AIO::sendfile $ofh, $ifh, $offset, $count
1127	Calls the "eio_sendfile_sync" function, which is like	1598	Calls the "eio_sendfile_sync" function, which is like
1128	"aio_sendfile", but is blocking (this makes most sense if you know	1599	"aio_sendfile", but is blocking (this makes most sense if you know
1129	the input data is likely cached already and the output filehandle is	1600	the input data is likely cached already and the output filehandle is
1130	set to non-blocking operations).	1601	set to non-blocking operations).
1131		1602
1132	Returns the number of bytes copied, or -1 on error.	1603	Returns the number of bytes copied, or -1 on error.
1133		1604
1134	IO::AIO::fadvise $fh, $offset, $len, $advice	1605	IO::AIO::fadvise $fh, $offset, $len, $advice
1135	Simply calls the "posix_fadvise" function (see it's manpage for	1606	Simply calls the "posix_fadvise" function (see its manpage for
1136	details). The following advice constants are avaiable:	1607	details). The following advice constants are available:
1137	"IO::AIO::FADV_NORMAL", "IO::AIO::FADV_SEQUENTIAL",	1608	"IO::AIO::FADV_NORMAL", "IO::AIO::FADV_SEQUENTIAL",
1138	"IO::AIO::FADV_RANDOM", "IO::AIO::FADV_NOREUSE",	1609	"IO::AIO::FADV_RANDOM", "IO::AIO::FADV_NOREUSE",
1139	"IO::AIO::FADV_WILLNEED", "IO::AIO::FADV_DONTNEED".	1610	"IO::AIO::FADV_WILLNEED", "IO::AIO::FADV_DONTNEED".
1140		1611
1141	On systems that do not implement "posix_fadvise", this function	1612	On systems that do not implement "posix_fadvise", this function
1142	returns ENOSYS, otherwise the return value of "posix_fadvise".	1613	returns ENOSYS, otherwise the return value of "posix_fadvise".
1143		1614
		1615	IO::AIO::madvise $scalar, $offset, $len, $advice
		1616	Simply calls the "posix_madvise" function (see its manpage for
		1617	details). The following advice constants are available:
		1618	"IO::AIO::MADV_NORMAL", "IO::AIO::MADV_SEQUENTIAL",
		1619	"IO::AIO::MADV_RANDOM", "IO::AIO::MADV_WILLNEED",
		1620	"IO::AIO::MADV_DONTNEED".
		1621
		1622	On systems that do not implement "posix_madvise", this function
		1623	returns ENOSYS, otherwise the return value of "posix_madvise".
		1624
		1625	IO::AIO::mprotect $scalar, $offset, $len, $protect
		1626	Simply calls the "mprotect" function on the preferably AIO::mmap'ed
		1627	$scalar (see its manpage for details). The following protect
		1628	constants are available: "IO::AIO::PROT_NONE", "IO::AIO::PROT_READ",
		1629	"IO::AIO::PROT_WRITE", "IO::AIO::PROT_EXEC".
		1630
		1631	On systems that do not implement "mprotect", this function returns
		1632	ENOSYS, otherwise the return value of "mprotect".
		1633
1144	IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]	1634	IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
1145	Memory-maps a file (or anonymous memory range) and attaches it to	1635	Memory-maps a file (or anonymous memory range) and attaches it to
1146	the given $scalar, which will act like a string scalar.	1636	the given $scalar, which will act like a string scalar. Returns true
		1637	on success, and false otherwise.
1147		1638
1148	The only operations allowed on the scalar are "substr"/"vec" that	1639	The only operations allowed on the scalar are "substr"/"vec" that
1149	don't change the string length, and most read-only operations such	1640	don't change the string length, and most read-only operations such
1150	as copying it or searching it with regexes and so on.	1641	as copying it or searching it with regexes and so on.
1151		1642
…		…
1165	"IO::AIO::PROT_EXEC", "IO::AIO::PROT_READ" and/or	1656	"IO::AIO::PROT_EXEC", "IO::AIO::PROT_READ" and/or
1166	"IO::AIO::PROT_WRITE",	1657	"IO::AIO::PROT_WRITE",
1167		1658
1168	$flags can be a combination of "IO::AIO::MAP_SHARED" or	1659	$flags can be a combination of "IO::AIO::MAP_SHARED" or
1169	"IO::AIO::MAP_PRIVATE", or a number of system-specific flags (when	1660	"IO::AIO::MAP_PRIVATE", or a number of system-specific flags (when
1170	not available, the are defined as 0): "IO::AIO::MAP_ANONYMOUS"	1661	not available, the are 0): "IO::AIO::MAP_ANONYMOUS" (which is set to
1171	(which is set to "MAP_ANON" if your system only provides this	1662	"MAP_ANON" if your system only provides this constant),
		1663	"IO::AIO::MAP_LOCKED", "IO::AIO::MAP_NORESERVE",
1172	constant), "IO::AIO::MAP_HUGETLB", "IO::AIO::MAP_LOCKED",	1664	"IO::AIO::MAP_POPULATE", "IO::AIO::MAP_NONBLOCK",
		1665	"IO::AIO::MAP_FIXED", "IO::AIO::MAP_GROWSDOWN",
1173	"IO::AIO::MAP_NORESERVE", "IO::AIO::MAP_POPULATE" or	1666	"IO::AIO::MAP_32BIT", "IO::AIO::MAP_HUGETLB" or
1174	"IO::AIO::MAP_NONBLOCK"	1667	"IO::AIO::MAP_STACK".
1175		1668
1176	If $fh is "undef", then a file descriptor of -1 is passed.	1669	If $fh is "undef", then a file descriptor of -1 is passed.
1177		1670
1178	$offset is the offset from the start of the file - it generally must	1671	$offset is the offset from the start of the file - it generally must
1179	be a multiple of "IO::AIO::PAGESIZE" and defaults to 0.	1672	be a multiple of "IO::AIO::PAGESIZE" and defaults to 0.
…		…
1192	my $fast_md5 = md5 $data;	1685	my $fast_md5 = md5 $data;
1193		1686
1194	IO::AIO::munmap $scalar	1687	IO::AIO::munmap $scalar
1195	Removes a previous mmap and undefines the $scalar.	1688	Removes a previous mmap and undefines the $scalar.
1196		1689
1197	IO::AIO::mlockall $flags	1690	IO::AIO::munlock $scalar, $offset = 0, $length = undef
1198	Calls the "mlockall" function with the given $flags (a combination	1691	Calls the "munlock" function, undoing the effects of a previous
1199	of "IO::AIO::MCL_CURRENT" and "IO::AIO::MCL__FUTURE").	1692	"aio_mlock" call (see its description for details).
1200
1201	On systems that do not implement "mlockall", this function returns
1202	ENOSYS, otherwise the return value of "mlockall".
1203		1693
1204	IO::AIO::munlockall	1694	IO::AIO::munlockall
1205	Calls the "munlockall" function.	1695	Calls the "munlockall" function.
1206		1696
1207	On systems that do not implement "munlockall", this function returns	1697	On systems that do not implement "munlockall", this function returns
1208	ENOSYS, otherwise the return value of "munlockall".	1698	ENOSYS, otherwise the return value of "munlockall".
		1699
		1700	IO::AIO::splice $r_fh, $r_off, $w_fh, $w_off, $length, $flags
		1701	Calls the GNU/Linux splice(2) syscall, if available. If $r_off or
		1702	$w_off are "undef", then "NULL" is passed for these, otherwise they
		1703	should be the file offset.
		1704
		1705	$r_fh and $w_fh should not refer to the same file, as splice might
		1706	silently corrupt the data in this case.
		1707
		1708	The following symbol flag values are available:
		1709	"IO::AIO::SPLICE_F_MOVE", "IO::AIO::SPLICE_F_NONBLOCK",
		1710	"IO::AIO::SPLICE_F_MORE" and "IO::AIO::SPLICE_F_GIFT".
		1711
		1712	See the splice(2) manpage for details.
		1713
		1714	IO::AIO::tee $r_fh, $w_fh, $length, $flags
		1715	Calls the GNU/Linux tee(2) syscall, see its manpage and the
		1716	description for "IO::AIO::splice" above for details.
		1717
		1718	$actual_size = IO::AIO::pipesize $r_fh[, $new_size]
		1719	Attempts to query or change the pipe buffer size. Obviously works
		1720	only on pipes, and currently works only on GNU/Linux systems, and
		1721	fails with -1/"ENOSYS" everywhere else. If anybody knows how to
		1722	influence pipe buffer size on other systems, drop me a note.
		1723
		1724	($rfh, $wfh) = IO::AIO::pipe2 [$flags]
		1725	This is a direct interface to the Linux pipe2(2) system call. If
		1726	$flags is missing or 0, then this should be the same as a call to
		1727	perl's built-in "pipe" function and create a new pipe, and works on
		1728	systems that lack the pipe2 syscall. On win32, this case invokes
		1729	"_pipe (..., 4096, O_BINARY)".
		1730
		1731	If $flags is non-zero, it tries to invoke the pipe2 system call with
		1732	the given flags (Linux 2.6.27, glibc 2.9).
		1733
		1734	On success, the read and write file handles are returned.
		1735
		1736	On error, nothing will be returned. If the pipe2 syscall is missing
		1737	and $flags is non-zero, fails with "ENOSYS".
		1738
		1739	Please refer to pipe2(2) for more info on the $flags, but at the
		1740	time of this writing, "IO::AIO::O_CLOEXEC", "IO::AIO::O_NONBLOCK"
		1741	and "IO::AIO::O_DIRECT" (Linux 3.4, for packet-based pipes) were
		1742	supported.
1209		1743
1210	EVENT LOOP INTEGRATION	1744	EVENT LOOP INTEGRATION
1211	It is recommended to use AnyEvent::AIO to integrate IO::AIO	1745	It is recommended to use AnyEvent::AIO to integrate IO::AIO
1212	automatically into many event loops:	1746	automatically into many event loops:
1213		1747
…		…
1236	# Danga::Socket integration	1770	# Danga::Socket integration
1237	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>	1771	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
1238	\&IO::AIO::poll_cb);	1772	\&IO::AIO::poll_cb);
1239		1773
1240	FORK BEHAVIOUR	1774	FORK BEHAVIOUR
1241	This module should do "the right thing" when the process using it forks:	1775	Usage of pthreads in a program changes the semantics of fork
		1776	considerably. Specifically, only async-safe functions can be called
		1777	after fork. Perl doesn't know about this, so in general, you cannot call
		1778	fork with defined behaviour in perl if pthreads are involved. IO::AIO
		1779	uses pthreads, so this applies, but many other extensions and (for
		1780	inexplicable reasons) perl itself often is linked against pthreads, so
		1781	this limitation applies to quite a lot of perls.
1242		1782
1243	Before the fork, IO::AIO enters a quiescent state where no requests can	1783	This module no longer tries to fight your OS, or POSIX. That means
1244	be added in other threads and no results will be processed. After the	1784	IO::AIO only works in the process that loaded it. Forking is fully
1245	fork the parent simply leaves the quiescent state and continues	1785	supported, but using IO::AIO in the child is not.
1246	request/result processing, while the child frees the request/result
1247	queue (so that the requests started before the fork will only be handled
1248	in the parent). Threads will be started on demand until the limit set in
1249	the parent process has been reached again.
1250		1786
1251	In short: the parent will, after a short pause, continue as if fork had	1787	You might get around by not using IO::AIO before (or after) forking.
1252	not been called, while the child will act as if IO::AIO has not been	1788	You could also try to call the IO::AIO::reinit function in the child:
1253	used yet.	1789
		1790	IO::AIO::reinit
		1791	Abandons all current requests and I/O threads and simply
		1792	reinitialises all data structures. This is not an operation
		1793	supported by any standards, but happens to work on GNU/Linux and
		1794	some newer BSD systems.
		1795
		1796	The only reasonable use for this function is to call it after
		1797	forking, if "IO::AIO" was used in the parent. Calling it while
		1798	IO::AIO is active in the process will result in undefined behaviour.
		1799	Calling it at any time will also result in any undefined (by POSIX)
		1800	behaviour.
1254		1801
1255	MEMORY USAGE	1802	MEMORY USAGE
1256	Per-request usage:	1803	Per-request usage:
1257		1804
1258	Each aio request uses - depending on your architecture - around 100-200	1805	Each aio request uses - depending on your architecture - around 100-200

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Comparing IO-AIO/README (file contents): Revision 1.43 by root, Sun Jan 10 23:44:02 2010 UTC vs. Revision 1.58 by root, Sun May 1 17:19:39 2016 UTC

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Comparing IO-AIO/README (file contents):
Revision 1.43 by root, Sun Jan 10 23:44:02 2010 UTC vs.
Revision 1.58 by root, Sun May 1 17:19:39 2016 UTC