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

Comparing IO-AIO/README (file contents):
Revision 1.41 by root, Sat Jan 2 14:24:32 2010 UTC vs.
Revision 1.54 by root, Sun Jan 6 11:48:14 2013 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
…		…
23	my $req = aio_unlink "/tmp/file", sub { };	23	my $req = aio_unlink "/tmp/file", sub { };
24	$req->cancel; # cancel request if still in queue	24	$req->cancel; # cancel request if still in queue
25		25
26	my $grp = aio_group sub { print "all stats done\n" };	26	my $grp = aio_group sub { print "all stats done\n" };
27	add $grp aio_stat "..." for ...;	27	add $grp aio_stat "..." for ...;
28
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		28
52	DESCRIPTION	29	DESCRIPTION
53	This module implements asynchronous I/O using whatever means your	30	This module implements asynchronous I/O using whatever means your
54	operating system supports. It is implemented as an interface to "libeio"	31	operating system supports. It is implemented as an interface to "libeio"
55	(<http://software.schmorp.de/pkg/libeio.html>).	32	(<http://software.schmorp.de/pkg/libeio.html>).
…		…
95		72
96	# register the IO::AIO callback with EV	73	# register the IO::AIO callback with EV
97	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;	74	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
98		75
99	# queue the request to open /etc/passwd	76	# queue the request to open /etc/passwd
100	aio_open "/etc/passwd", O_RDONLY, 0, sub {	77	aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
101	my $fh = shift	78	my $fh = shift
102	or die "error while opening: $!";	79	or die "error while opening: $!";
103		80
104	# stat'ing filehandles is generally non-blocking	81	# stat'ing filehandles is generally non-blocking
105	my $size = -s $fh;	82	my $size = -s $fh;
…		…
168	anymore (except possibly for the Perl object, but its connection to	145	anymore (except possibly for the Perl object, but its connection to
169	the actual aio request is severed and calling its methods will	146	the actual aio request is severed and calling its methods will
170	either do nothing or result in a runtime error).	147	either do nothing or result in a runtime error).
171		148
172	FUNCTIONS	149	FUNCTIONS
173	AIO REQUEST FUNCTIONS	150	QUICK OVERVIEW
		151	This section simply lists the prototypes most of the functions for quick
		152	reference. See the following sections for function-by-function
		153	documentation.
		154
		155	aio_wd $pathname, $callback->($wd)
		156	aio_open $pathname, $flags, $mode, $callback->($fh)
		157	aio_close $fh, $callback->($status)
		158	aio_seek $fh,$offset,$whence, $callback->($offs)
		159	aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
		160	aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
		161	aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
		162	aio_readahead $fh,$offset,$length, $callback->($retval)
		163	aio_stat $fh_or_path, $callback->($status)
		164	aio_lstat $fh, $callback->($status)
		165	aio_statvfs $fh_or_path, $callback->($statvfs)
		166	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
		167	aio_chown $fh_or_path, $uid, $gid, $callback->($status)
		168	aio_chmod $fh_or_path, $mode, $callback->($status)
		169	aio_truncate $fh_or_path, $offset, $callback->($status)
		170	aio_allocate $fh, $mode, $offset, $len, $callback->($status)
		171	aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
		172	aio_unlink $pathname, $callback->($status)
		173	aio_mknod $pathname, $mode, $dev, $callback->($status)
		174	aio_link $srcpath, $dstpath, $callback->($status)
		175	aio_symlink $srcpath, $dstpath, $callback->($status)
		176	aio_readlink $pathname, $callback->($link)
		177	aio_realpath $pathname, $callback->($link)
		178	aio_rename $srcpath, $dstpath, $callback->($status)
		179	aio_mkdir $pathname, $mode, $callback->($status)
		180	aio_rmdir $pathname, $callback->($status)
		181	aio_readdir $pathname, $callback->($entries)
		182	aio_readdirx $pathname, $flags, $callback->($entries, $flags)
		183	IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST
		184	IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN
		185	aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
		186	aio_load $pathname, $data, $callback->($status)
		187	aio_copy $srcpath, $dstpath, $callback->($status)
		188	aio_move $srcpath, $dstpath, $callback->($status)
		189	aio_rmtree $pathname, $callback->($status)
		190	aio_sync $callback->($status)
		191	aio_syncfs $fh, $callback->($status)
		192	aio_fsync $fh, $callback->($status)
		193	aio_fdatasync $fh, $callback->($status)
		194	aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
		195	aio_pathsync $pathname, $callback->($status)
		196	aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		197	aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		198	aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
		199	aio_mlockall $flags, $callback->($status)
		200	aio_group $callback->(...)
		201	aio_nop $callback->()
		202
		203	$prev_pri = aioreq_pri [$pri]
		204	aioreq_nice $pri_adjust
		205
		206	IO::AIO::poll_wait
		207	IO::AIO::poll_cb
		208	IO::AIO::poll
		209	IO::AIO::flush
		210	IO::AIO::max_poll_reqs $nreqs
		211	IO::AIO::max_poll_time $seconds
		212	IO::AIO::min_parallel $nthreads
		213	IO::AIO::max_parallel $nthreads
		214	IO::AIO::max_idle $nthreads
		215	IO::AIO::idle_timeout $seconds
		216	IO::AIO::max_outstanding $maxreqs
		217	IO::AIO::nreqs
		218	IO::AIO::nready
		219	IO::AIO::npending
		220
		221	IO::AIO::sendfile $ofh, $ifh, $offset, $count
		222	IO::AIO::fadvise $fh, $offset, $len, $advice
		223	IO::AIO::mmap $scalar, $length, $prot, $flags[, $fh[, $offset]]
		224	IO::AIO::munmap $scalar
		225	IO::AIO::madvise $scalar, $offset, $length, $advice
		226	IO::AIO::mprotect $scalar, $offset, $length, $protect
		227	IO::AIO::munlock $scalar, $offset = 0, $length = undef
		228	IO::AIO::munlockall
		229
		230	API NOTES
174	All the "aio_*" calls are more or less thin wrappers around the syscall	231	All the "aio_*" calls are more or less thin wrappers around the syscall
175	with the same name (sans "aio_"). The arguments are similar or	232	with the same name (sans "aio_"). The arguments are similar or
176	identical, and they all accept an additional (and optional) $callback	233	identical, and they all accept an additional (and optional) $callback
177	argument which must be a code reference. This code reference will get	234	argument which must be a code reference. This code reference will be
178	called with the syscall return code (e.g. most syscalls return -1 on
179	error, unlike perl, which usually delivers "false") as its sole argument
180	after the given syscall has been executed asynchronously.	235	called after the syscall has been executed in an asynchronous fashion.
		236	The results of the request will be passed as arguments to the callback
		237	(and, if an error occured, in $!) - for most requests the syscall return
		238	code (e.g. most syscalls return -1 on error, unlike perl, which usually
		239	delivers "false").
		240
		241	Some requests (such as "aio_readdir") pass the actual results and
		242	communicate failures by passing "undef".
181		243
182	All functions expecting a filehandle keep a copy of the filehandle	244	All functions expecting a filehandle keep a copy of the filehandle
183	internally until the request has finished.	245	internally until the request has finished.
184		246
185	All functions return request objects of type IO::AIO::REQ that allow	247	All functions return request objects of type IO::AIO::REQ that allow
186	further manipulation of those requests while they are in-flight.	248	further manipulation of those requests while they are in-flight.
187		249
188	The pathnames you pass to these routines must be absolute and encoded	250	The pathnames you pass to these routines should be absolute. The
189	as octets. The reason for the former is that at the time the request is	251	reason for this is that at the time the request is being executed, the
190	being executed, the current working directory could have changed.	252	current working directory could have changed. Alternatively, you can
191	Alternatively, you can make sure that you never change the current	253	make sure that you never change the current working directory anywhere
192	working directory anywhere in the program and then use relative paths.	254	in the program and then use relative paths. You can also take advantage
		255	of IO::AIOs working directory abstraction, that lets you specify paths
		256	relative to some previously-opened "working directory object" - see the
		257	description of the "IO::AIO::WD" class later in this document.
193		258
194	To encode pathnames as octets, either make sure you either: a) always	259	To encode pathnames as octets, either make sure you either: a) always
195	pass in filenames you got from outside (command line, readdir etc.)	260	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	261	without tinkering, b) are in your native filesystem encoding, c) use the
197	and encode your pathnames to the locale (or other) encoding in effect in	262	Encode module and encode your pathnames to the locale (or other)
198	the user environment, d) use Glib::filename_from_unicode on unicode	263	encoding in effect in the user environment, d) use
199	filenames or e) use something else to ensure your scalar has the correct	264	Glib::filename_from_unicode on unicode filenames or e) use something
200	contents.	265	else to ensure your scalar has the correct contents.
201		266
202	This works, btw. independent of the internal UTF-8 bit, which IO::AIO	267	This works, btw. independent of the internal UTF-8 bit, which IO::AIO
203	handles correctly whether it is set or not.	268	handles correctly whether it is set or not.
204		269
		270	AIO REQUEST FUNCTIONS
205	$prev_pri = aioreq_pri [$pri]	271	$prev_pri = aioreq_pri [$pri]
206	Returns the priority value that would be used for the next request	272	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.	273	and, if $pri is given, sets the priority for the next aio request.
208		274
209	The default priority is 0, the minimum and maximum priorities are -4	275	The default priority is 0, the minimum and maximum priorities are -4
…		…
231	Similar to "aioreq_pri", but subtracts the given value from the	297	Similar to "aioreq_pri", but subtracts the given value from the
232	current priority, so the effect is cumulative.	298	current priority, so the effect is cumulative.
233		299
234	aio_open $pathname, $flags, $mode, $callback->($fh)	300	aio_open $pathname, $flags, $mode, $callback->($fh)
235	Asynchronously open or create a file and call the callback with a	301	Asynchronously open or create a file and call the callback with a
236	newly created filehandle for the file.	302	newly created filehandle for the file (or "undef" in case of an
		303	error).
237		304
238	The pathname passed to "aio_open" must be absolute. See API NOTES,	305	The pathname passed to "aio_open" must be absolute. See API NOTES,
239	above, for an explanation.	306	above, for an explanation.
240		307
241	The $flags argument is a bitmask. See the "Fcntl" module for a list.	308	The $flags argument is a bitmask. See the "Fcntl" module for a list.
…		…
248	will be modified by the umask in effect then the request is being	315	will be modified by the umask in effect then the request is being
249	executed, so better never change the umask.	316	executed, so better never change the umask.
250		317
251	Example:	318	Example:
252		319
253	aio_open "/etc/passwd", O_RDONLY, 0, sub {	320	aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
254	if ($_[0]) {	321	if ($_[0]) {
255	print "open successful, fh is $_[0]\n";	322	print "open successful, fh is $_[0]\n";
256	...	323	...
257	} else {	324	} else {
258	die "open failed: $!\n";	325	die "open failed: $!\n";
259	}	326	}
260	};	327	};
261		328
		329	In addition to all the common open modes/flags ("O_RDONLY",
		330	"O_WRONLY", "O_RDWR", "O_CREAT", "O_TRUNC", "O_EXCL" and
		331	"O_APPEND"), the following POSIX and non-POSIX constants are
		332	available (missing ones on your system are, as usual, 0):
		333
		334	"O_ASYNC", "O_DIRECT", "O_NOATIME", "O_CLOEXEC", "O_NOCTTY",
		335	"O_NOFOLLOW", "O_NONBLOCK", "O_EXEC", "O_SEARCH", "O_DIRECTORY",
		336	"O_DSYNC", "O_RSYNC", "O_SYNC" and "O_TTY_INIT".
		337
262	aio_close $fh, $callback->($status)	338	aio_close $fh, $callback->($status)
263	Asynchronously close a file and call the callback with the result	339	Asynchronously close a file and call the callback with the result
264	code.	340	code.
265		341
266	Unfortunately, you can't do this to perl. Perl insists very	342	Unfortunately, you can't do this to perl. Perl insists very
…		…
271	will use dup2 to overwrite the file descriptor with the write-end of	347	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).	348	a pipe (the pipe fd will be created on demand and will be cached).
273		349
274	Or in other words: the file descriptor will be closed, but it will	350	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.	351	not be free for reuse until the perl filehandle is closed.
		352
		353	aio_seek $fh, $offset, $whence, $callback->($offs)
		354	Seeks the filehandle to the new $offset, similarly to perl's
		355	"sysseek". The $whence can use the traditional values (0 for
		356	"IO::AIO::SEEK_SET", 1 for "IO::AIO::SEEK_CUR" or 2 for
		357	"IO::AIO::SEEK_END").
		358
		359	The resulting absolute offset will be passed to the callback, or -1
		360	in case of an error.
		361
		362	In theory, the $whence constants could be different than the
		363	corresponding values from Fcntl, but perl guarantees they are the
		364	same, so don't panic.
		365
		366	As a GNU/Linux (and maybe Solaris) extension, also the constants
		367	"IO::AIO::SEEK_DATA" and "IO::AIO::SEEK_HOLE" are available, if they
		368	could be found. No guarantees about suitability for use in
		369	"aio_seek" or Perl's "sysseek" can be made though, although I would
		370	naively assume they "just work".
276		371
277	aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	372	aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
278	aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	373	aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
279	Reads or writes $length bytes from or to the specified $fh and	374	Reads or writes $length bytes from or to the specified $fh and
280	$offset into the scalar given by $data and offset $dataoffset and	375	$offset into the scalar given by $data and offset $dataoffset and
…		…
309	aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)	404	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	405	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	406	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	407	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	408	more than one "aio_sendfile" per $out_fh, as they will interfere
314	with each other.	409	with each other. The same $in_fh works fine though, as this function
		410	does not move or use the file offset of $in_fh.
315		411
		412	Please note that "aio_sendfile" can read more bytes from $in_fh than
		413	are written, and there is no way to find out how many more bytes
		414	have been read from "aio_sendfile" alone, as "aio_sendfile" only
		415	provides the number of bytes written to $out_fh. Only if the result
		416	value equals $length one can assume that $length bytes have been
		417	read.
		418
		419	Unlike with other "aio_" functions, it makes a lot of sense to use
		420	"aio_sendfile" on non-blocking sockets, as long as one end
		421	(typically the $in_fh) is a file - the file I/O will then be
		422	asynchronous, while the socket I/O will be non-blocking. Note,
		423	however, that you can run into a trap where "aio_sendfile" reads
		424	some data with readahead, then fails to write all data, and when the
		425	socket is ready the next time, the data in the cache is already
		426	lost, forcing "aio_sendfile" to again hit the disk. Explicit
		427	"aio_read" + "aio_write" let's you better control resource usage.
		428
316	This call tries to make use of a native "sendfile" syscall to	429	This call tries to make use of a native "sendfile"-like syscall to
317	provide zero-copy operation. For this to work, $out_fh should refer	430	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.	431	to a socket, and $in_fh should refer to an mmap'able file.
319		432
320	If a native sendfile cannot be found or it fails with "ENOSYS",	433	If a native sendfile cannot be found or it fails with "ENOSYS",
321	"ENOTSUP", "EOPNOTSUPP", "EAFNOSUPPORT", "EPROTOTYPE" or "ENOTSOCK",	434	"EINVAL", "ENOTSUP", "EOPNOTSUPP", "EAFNOSUPPORT", "EPROTOTYPE" or
322	it will be emulated, so you can call "aio_sendfile" on any type of	435	"ENOTSOCK", it will be emulated, so you can call "aio_sendfile" on
323	filehandle regardless of the limitations of the operating system.	436	any type of filehandle regardless of the limitations of the
		437	operating system.
324		438
325	Please note, however, that "aio_sendfile" can read more bytes from	439	As native sendfile syscalls (as practically any non-POSIX interface
326	$in_fh than are written, and there is no way to find out how many	440	hacked together in a hurry to improve benchmark numbers) tend to be
327	bytes have been read from "aio_sendfile" alone, as "aio_sendfile"	441	rather buggy on many systems, this implementation tries to work
328	only provides the number of bytes written to $out_fh. Only if the	442	around some known bugs in Linux and FreeBSD kernels (probably
329	result value equals $length one can assume that $length bytes have	443	others, too), but that might fail, so you really really should check
330	been read.	444	the return value of "aio_sendfile" - fewre bytes than expected might
		445	have been transferred.
331		446
332	aio_readahead $fh,$offset,$length, $callback->($retval)	447	aio_readahead $fh,$offset,$length, $callback->($retval)
333	"aio_readahead" populates the page cache with data from a file so	448	"aio_readahead" populates the page cache with data from a file so
334	that subsequent reads from that file will not block on disk I/O. The	449	that subsequent reads from that file will not block on disk I/O. The
335	$offset argument specifies the starting point from which data is to	450	$offset argument specifies the starting point from which data is to
…		…
356	Currently, the stats are always 64-bit-stats, i.e. instead of	471	Currently, the stats are always 64-bit-stats, i.e. instead of
357	returning an error when stat'ing a large file, the results will be	472	returning an error when stat'ing a large file, the results will be
358	silently truncated unless perl itself is compiled with large file	473	silently truncated unless perl itself is compiled with large file
359	support.	474	support.
360		475
		476	To help interpret the mode and dev/rdev stat values, IO::AIO offers
		477	the following constants and functions (if not implemented, the
		478	constants will be 0 and the functions will either "croak" or fall
		479	back on traditional behaviour).
		480
		481	"S_IFMT", "S_IFIFO", "S_IFCHR", "S_IFBLK", "S_IFLNK", "S_IFREG",
		482	"S_IFDIR", "S_IFWHT", "S_IFSOCK", "IO::AIO::major $dev_t",
		483	"IO::AIO::minor $dev_t", "IO::AIO::makedev $major, $minor".
		484
361	Example: Print the length of /etc/passwd:	485	Example: Print the length of /etc/passwd:
362		486
363	aio_stat "/etc/passwd", sub {	487	aio_stat "/etc/passwd", sub {
364	$_[0] and die "stat failed: $!";	488	$_[0] and die "stat failed: $!";
365	print "size is ", -s _, "\n";	489	print "size is ", -s _, "\n";
366	};	490	};
367		491
		492	aio_statvfs $fh_or_path, $callback->($statvfs)
		493	Works like the POSIX "statvfs" or "fstatvfs" syscalls, depending on
		494	whether a file handle or path was passed.
		495
		496	On success, the callback is passed a hash reference with the
		497	following members: "bsize", "frsize", "blocks", "bfree", "bavail",
		498	"files", "ffree", "favail", "fsid", "flag" and "namemax". On
		499	failure, "undef" is passed.
		500
		501	The following POSIX IO::AIO::ST_* constants are defined: "ST_RDONLY"
		502	and "ST_NOSUID".
		503
		504	The following non-POSIX IO::AIO::ST_* flag masks are defined to
		505	their correct value when available, or to 0 on systems that do not
		506	support them: "ST_NODEV", "ST_NOEXEC", "ST_SYNCHRONOUS",
		507	"ST_MANDLOCK", "ST_WRITE", "ST_APPEND", "ST_IMMUTABLE",
		508	"ST_NOATIME", "ST_NODIRATIME" and "ST_RELATIME".
		509
		510	Example: stat "/wd" and dump out the data if successful.
		511
		512	aio_statvfs "/wd", sub {
		513	my $f = $_[0]
		514	or die "statvfs: $!";
		515
		516	use Data::Dumper;
		517	say Dumper $f;
		518	};
		519
		520	# result:
		521	{
		522	bsize => 1024,
		523	bfree => 4333064312,
		524	blocks => 10253828096,
		525	files => 2050765568,
		526	flag => 4096,
		527	favail => 2042092649,
		528	bavail => 4333064312,
		529	ffree => 2042092649,
		530	namemax => 255,
		531	frsize => 1024,
		532	fsid => 1810
		533	}
		534
		535	Here is a (likely partial) list of fsid values used by Linux - it is
		536	safe to hardcode these when the $^O is "linux":
		537
		538	0x0000adf5 adfs
		539	0x0000adff affs
		540	0x5346414f afs
		541	0x09041934 anon-inode filesystem
		542	0x00000187 autofs
		543	0x42465331 befs
		544	0x1badface bfs
		545	0x42494e4d binfmt_misc
		546	0x9123683e btrfs
		547	0x0027e0eb cgroupfs
		548	0xff534d42 cifs
		549	0x73757245 coda
		550	0x012ff7b7 coh
		551	0x28cd3d45 cramfs
		552	0x453dcd28 cramfs-wend (wrong endianness)
		553	0x64626720 debugfs
		554	0x00001373 devfs
		555	0x00001cd1 devpts
		556	0x0000f15f ecryptfs
		557	0x00414a53 efs
		558	0x0000137d ext
		559	0x0000ef53 ext2/ext3
		560	0x0000ef51 ext2
		561	0x00004006 fat
		562	0x65735546 fuseblk
		563	0x65735543 fusectl
		564	0x0bad1dea futexfs
		565	0x01161970 gfs2
		566	0x47504653 gpfs
		567	0x00004244 hfs
		568	0xf995e849 hpfs
		569	0x958458f6 hugetlbfs
		570	0x2bad1dea inotifyfs
		571	0x00009660 isofs
		572	0x000072b6 jffs2
		573	0x3153464a jfs
		574	0x6b414653 k-afs
		575	0x0bd00bd0 lustre
		576	0x0000137f minix
		577	0x0000138f minix 30 char names
		578	0x00002468 minix v2
		579	0x00002478 minix v2 30 char names
		580	0x00004d5a minix v3
		581	0x19800202 mqueue
		582	0x00004d44 msdos
		583	0x0000564c novell
		584	0x00006969 nfs
		585	0x6e667364 nfsd
		586	0x00003434 nilfs
		587	0x5346544e ntfs
		588	0x00009fa1 openprom
		589	0x7461636F ocfs2
		590	0x00009fa0 proc
		591	0x6165676c pstorefs
		592	0x0000002f qnx4
		593	0x858458f6 ramfs
		594	0x52654973 reiserfs
		595	0x00007275 romfs
		596	0x67596969 rpc_pipefs
		597	0x73636673 securityfs
		598	0xf97cff8c selinux
		599	0x0000517b smb
		600	0x534f434b sockfs
		601	0x73717368 squashfs
		602	0x62656572 sysfs
		603	0x012ff7b6 sysv2
		604	0x012ff7b5 sysv4
		605	0x01021994 tmpfs
		606	0x15013346 udf
		607	0x00011954 ufs
		608	0x54190100 ufs byteswapped
		609	0x00009fa2 usbdevfs
		610	0x01021997 v9fs
		611	0xa501fcf5 vxfs
		612	0xabba1974 xenfs
		613	0x012ff7b4 xenix
		614	0x58465342 xfs
		615	0x012fd16d xia
		616
368	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)	617	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
369	Works like perl's "utime" function (including the special case of	618	Works like perl's "utime" function (including the special case of
370	$atime and $mtime being undef). Fractional times are supported if	619	$atime and $mtime being undef). Fractional times are supported if
371	the underlying syscalls support them.	620	the underlying syscalls support them.
372		621
…		…
394	aio_chown "path", 0, undef;	643	aio_chown "path", 0, undef;
395		644
396	aio_truncate $fh_or_path, $offset, $callback->($status)	645	aio_truncate $fh_or_path, $offset, $callback->($status)
397	Works like truncate(2) or ftruncate(2).	646	Works like truncate(2) or ftruncate(2).
398		647
		648	aio_allocate $fh, $mode, $offset, $len, $callback->($status)
		649	Allocates or freed disk space according to the $mode argument. See
		650	the linux "fallocate" docuemntation for details.
		651
		652	$mode can currently be 0 or "IO::AIO::FALLOC_FL_KEEP_SIZE" to
		653	allocate space, or "IO::AIO::FALLOC_FL_PUNCH_HOLE \|
		654	IO::AIO::FALLOC_FL_KEEP_SIZE", to deallocate a file range.
		655
		656	The file system block size used by "fallocate" is presumably the
		657	"f_bsize" returned by "statvfs".
		658
		659	If "fallocate" isn't available or cannot be emulated (currently no
		660	emulation will be attempted), passes -1 and sets $! to "ENOSYS".
		661
399	aio_chmod $fh_or_path, $mode, $callback->($status)	662	aio_chmod $fh_or_path, $mode, $callback->($status)
400	Works like perl's "chmod" function.	663	Works like perl's "chmod" function.
401		664
402	aio_unlink $pathname, $callback->($status)	665	aio_unlink $pathname, $callback->($status)
403	Asynchronously unlink (delete) a file and call the callback with the	666	Asynchronously unlink (delete) a file and call the callback with the
404	result code.	667	result code.
405		668
406	aio_mknod $path, $mode, $dev, $callback->($status)	669	aio_mknod $pathname, $mode, $dev, $callback->($status)
407	[EXPERIMENTAL]	670	[EXPERIMENTAL]
408		671
409	Asynchronously create a device node (or fifo). See mknod(2).	672	Asynchronously create a device node (or fifo). See mknod(2).
410		673
411	The only (POSIX-) portable way of calling this function is:	674	The only (POSIX-) portable way of calling this function is:
412		675
413	aio_mknod $path, IO::AIO::S_IFIFO \| $mode, 0, sub { ...	676	aio_mknod $pathname, IO::AIO::S_IFIFO \| $mode, 0, sub { ...
		677
		678	See "aio_stat" for info about some potentially helpful extra
		679	constants and functions.
414		680
415	aio_link $srcpath, $dstpath, $callback->($status)	681	aio_link $srcpath, $dstpath, $callback->($status)
416	Asynchronously create a new link to the existing object at $srcpath	682	Asynchronously create a new link to the existing object at $srcpath
417	at the path $dstpath and call the callback with the result code.	683	at the path $dstpath and call the callback with the result code.
418		684
419	aio_symlink $srcpath, $dstpath, $callback->($status)	685	aio_symlink $srcpath, $dstpath, $callback->($status)
420	Asynchronously create a new symbolic link to the existing object at	686	Asynchronously create a new symbolic link to the existing object at
421	$srcpath at the path $dstpath and call the callback with the result	687	$srcpath at the path $dstpath and call the callback with the result
422	code.	688	code.
423		689
424	aio_readlink $path, $callback->($link)	690	aio_readlink $pathname, $callback->($link)
425	Asynchronously read the symlink specified by $path and pass it to	691	Asynchronously read the symlink specified by $path and pass it to
426	the callback. If an error occurs, nothing or undef gets passed to	692	the callback. If an error occurs, nothing or undef gets passed to
427	the callback.	693	the callback.
428		694
		695	aio_realpath $pathname, $callback->($path)
		696	Asynchronously make the path absolute and resolve any symlinks in
		697	$path. The resulting path only consists of directories (same as
		698	Cwd::realpath).
		699
		700	This request can be used to get the absolute path of the current
		701	working directory by passing it a path of . (a single dot).
		702
429	aio_rename $srcpath, $dstpath, $callback->($status)	703	aio_rename $srcpath, $dstpath, $callback->($status)
430	Asynchronously rename the object at $srcpath to $dstpath, just as	704	Asynchronously rename the object at $srcpath to $dstpath, just as
431	rename(2) and call the callback with the result code.	705	rename(2) and call the callback with the result code.
		706
		707	On systems that support the AIO::WD working directory abstraction
		708	natively, the case "[$wd, "."]" as $srcpath is specialcased -
		709	instead of failing, "rename" is called on the absolute path of $wd.
432		710
433	aio_mkdir $pathname, $mode, $callback->($status)	711	aio_mkdir $pathname, $mode, $callback->($status)
434	Asynchronously mkdir (create) a directory and call the callback with	712	Asynchronously mkdir (create) a directory and call the callback with
435	the result code. $mode will be modified by the umask at the time the	713	the result code. $mode will be modified by the umask at the time the
436	request is executed, so do not change your umask.	714	request is executed, so do not change your umask.
437		715
438	aio_rmdir $pathname, $callback->($status)	716	aio_rmdir $pathname, $callback->($status)
439	Asynchronously rmdir (delete) a directory and call the callback with	717	Asynchronously rmdir (delete) a directory and call the callback with
440	the result code.	718	the result code.
441		719
		720	On systems that support the AIO::WD working directory abstraction
		721	natively, the case "[$wd, "."]" is specialcased - instead of
		722	failing, "rmdir" is called on the absolute path of $wd.
		723
442	aio_readdir $pathname, $callback->($entries)	724	aio_readdir $pathname, $callback->($entries)
443	Unlike the POSIX call of the same name, "aio_readdir" reads an	725	Unlike the POSIX call of the same name, "aio_readdir" reads an
444	entire directory (i.e. opendir + readdir + closedir). The entries	726	entire directory (i.e. opendir + readdir + closedir). The entries
445	will not be sorted, and will NOT include the "." and ".." entries.	727	will not be sorted, and will NOT include the "." and ".." entries.
446		728
447	The callback is passed a single argument which is either "undef" or	729	The callback is passed a single argument which is either "undef" or
448	an array-ref with the filenames.	730	an array-ref with the filenames.
449		731
450	aio_readdirx $pathname, $flags, $callback->($entries, $flags)	732	aio_readdirx $pathname, $flags, $callback->($entries, $flags)
451	Quite similar to "aio_readdir", but the $flags argument allows to	733	Quite similar to "aio_readdir", but the $flags argument allows one
452	tune behaviour and output format. In case of an error, $entries will	734	to tune behaviour and output format. In case of an error, $entries
453	be "undef".	735	will be "undef".
454		736
455	The flags are a combination of the following constants, ORed	737	The flags are a combination of the following constants, ORed
456	together (the flags will also be passed to the callback, possibly	738	together (the flags will also be passed to the callback, possibly
457	modified):	739	modified):
458		740
459	IO::AIO::READDIR_DENTS	741	IO::AIO::READDIR_DENTS
460	When this flag is off, then the callback gets an arrayref with	742	When this flag is off, then the callback gets an arrayref
461	of names only (as with "aio_readdir"), otherwise it gets an	743	consisting of names only (as with "aio_readdir"), otherwise it
462	arrayref with "[$name, $type, $inode]" arrayrefs, each	744	gets an arrayref with "[$name, $type, $inode]" arrayrefs, each
463	describing a single directory entry in more detail.	745	describing a single directory entry in more detail.
464		746
465	$name is the name of the entry.	747	$name is the name of the entry.
466		748
467	$type is one of the "IO::AIO::DT_xxx" constants:	749	$type is one of the "IO::AIO::DT_xxx" constants:
…		…
480	unspecified content on systems that do not deliver the inode	762	unspecified content on systems that do not deliver the inode
481	information.	763	information.
482		764
483	IO::AIO::READDIR_DIRS_FIRST	765	IO::AIO::READDIR_DIRS_FIRST
484	When this flag is set, then the names will be returned in an	766	When this flag is set, then the names will be returned in an
485	order where likely directories come first. This is useful when	767	order where likely directories come first, in optimal stat
486	you need to quickly find directories, or you want to find all	768	order. This is useful when you need to quickly find directories,
487	directories while avoiding to stat() each entry.	769	or you want to find all directories while avoiding to stat()
		770	each entry.
488		771
489	If the system returns type information in readdir, then this is	772	If the system returns type information in readdir, then this is
490	used to find directories directly. Otherwise, likely directories	773	used to find directories directly. Otherwise, likely directories
491	are files beginning with ".", or otherwise files with no dots,	774	are names beginning with ".", or otherwise names with no dots,
492	of which files with short names are tried first.	775	of which names with short names are tried first.
493		776
494	IO::AIO::READDIR_STAT_ORDER	777	IO::AIO::READDIR_STAT_ORDER
495	When this flag is set, then the names will be returned in an	778	When this flag is set, then the names will be returned in an
496	order suitable for stat()'ing each one. That is, when you plan	779	order suitable for stat()'ing each one. That is, when you plan
497	to stat() all files in the given directory, then the returned	780	to stat() all files in the given directory, then the returned
…		…
502	optimal stat order.	785	optimal stat order.
503		786
504	IO::AIO::READDIR_FOUND_UNKNOWN	787	IO::AIO::READDIR_FOUND_UNKNOWN
505	This flag should not be set when calling "aio_readdirx".	788	This flag should not be set when calling "aio_readdirx".
506	Instead, it is being set by "aio_readdirx", when any of the	789	Instead, it is being set by "aio_readdirx", when any of the
507	$type's found were "IO::AIO::DT_UNKNOWN". The absense of this	790	$type's found were "IO::AIO::DT_UNKNOWN". The absence of this
508	flag therefore indicates that all $type's are known, which can	791	flag therefore indicates that all $type's are known, which can
509	be used to speed up some algorithms.	792	be used to speed up some algorithms.
510		793
511	aio_load $path, $data, $callback->($status)	794	aio_load $pathname, $data, $callback->($status)
512	This is a composite request that tries to fully load the given file	795	This is a composite request that tries to fully load the given file
513	into memory. Status is the same as with aio_read.	796	into memory. Status is the same as with aio_read.
514		797
515	aio_copy $srcpath, $dstpath, $callback->($status)	798	aio_copy $srcpath, $dstpath, $callback->($status)
516	Try to copy the file (directories not supported as either source	799	Try to copy the file (directories not supported as either source
…		…
533		816
534	This is a composite request that tries to rename(2) the file first;	817	This is a composite request that tries to rename(2) the file first;
535	if rename fails with "EXDEV", it copies the file with "aio_copy"	818	if rename fails with "EXDEV", it copies the file with "aio_copy"
536	and, if that is successful, unlinks the $srcpath.	819	and, if that is successful, unlinks the $srcpath.
537		820
538	aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	821	aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
539	Scans a directory (similar to "aio_readdir") but additionally tries	822	Scans a directory (similar to "aio_readdir") but additionally tries
540	to efficiently separate the entries of directory $path into two sets	823	to efficiently separate the entries of directory $path into two sets
541	of names, directories you can recurse into (directories), and ones	824	of names, directories you can recurse into (directories), and ones
542	you cannot recurse into (everything else, including symlinks to	825	you cannot recurse into (everything else, including symlinks to
543	directories).	826	directories).
…		…
576	Then entries will be sorted into likely directories a non-initial	859	Then entries will be sorted into likely directories a non-initial
577	dot currently) and likely non-directories (see "aio_readdirx"). Then	860	dot currently) and likely non-directories (see "aio_readdirx"). Then
578	every entry plus an appended "/." will be "stat"'ed, likely	861	every entry plus an appended "/." will be "stat"'ed, likely
579	directories first, in order of their inode numbers. If that	862	directories first, in order of their inode numbers. If that
580	succeeds, it assumes that the entry is a directory or a symlink to	863	succeeds, it assumes that the entry is a directory or a symlink to
581	directory (which will be checked seperately). This is often faster	864	directory (which will be checked separately). This is often faster
582	than stat'ing the entry itself because filesystems might detect the	865	than stat'ing the entry itself because filesystems might detect the
583	type of the entry without reading the inode data (e.g. ext2fs	866	type of the entry without reading the inode data (e.g. ext2fs
584	filetype feature), even on systems that cannot return the filetype	867	filetype feature), even on systems that cannot return the filetype
585	information on readdir.	868	information on readdir.
586		869
…		…
592		875
593	It will also likely work on non-POSIX filesystems with reduced	876	It will also likely work on non-POSIX filesystems with reduced
594	efficiency as those tend to return 0 or 1 as link counts, which	877	efficiency as those tend to return 0 or 1 as link counts, which
595	disables the directory counting heuristic.	878	disables the directory counting heuristic.
596		879
597	aio_rmtree $path, $callback->($status)	880	aio_rmtree $pathname, $callback->($status)
598	Delete a directory tree starting (and including) $path, return the	881	Delete a directory tree starting (and including) $path, return the
599	status of the final "rmdir" only. This is a composite request that	882	status of the final "rmdir" only. This is a composite request that
600	uses "aio_scandir" to recurse into and rmdir directories, and unlink	883	uses "aio_scandir" to recurse into and rmdir directories, and unlink
601	everything else.	884	everything else.
602		885
…		…
611	Asynchronously call fdatasync on the given filehandle and call the	894	Asynchronously call fdatasync on the given filehandle and call the
612	callback with the fdatasync result code.	895	callback with the fdatasync result code.
613		896
614	If this call isn't available because your OS lacks it or it couldn't	897	If this call isn't available because your OS lacks it or it couldn't
615	be detected, it will be emulated by calling "fsync" instead.	898	be detected, it will be emulated by calling "fsync" instead.
		899
		900	aio_syncfs $fh, $callback->($status)
		901	Asynchronously call the syncfs syscall to sync the filesystem
		902	associated to the given filehandle and call the callback with the
		903	syncfs result code. If syncfs is not available, calls sync(), but
		904	returns -1 and sets errno to "ENOSYS" nevertheless.
616		905
617	aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)	906	aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
618	Sync the data portion of the file specified by $offset and $length	907	Sync the data portion of the file specified by $offset and $length
619	to disk (but NOT the metadata), by calling the Linux-specific	908	to disk (but NOT the metadata), by calling the Linux-specific
620	sync_file_range call. If sync_file_range is not available or it	909	sync_file_range call. If sync_file_range is not available or it
…		…
624	"IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE",	913	"IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE",
625	"IO::AIO::SYNC_FILE_RANGE_WRITE" and	914	"IO::AIO::SYNC_FILE_RANGE_WRITE" and
626	"IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER": refer to the sync_file_range	915	"IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER": refer to the sync_file_range
627	manpage for details.	916	manpage for details.
628		917
629	aio_pathsync $path, $callback->($status)	918	aio_pathsync $pathname, $callback->($status)
630	This request tries to open, fsync and close the given path. This is	919	This request tries to open, fsync and close the given path. This is
631	a composite request intended to sync directories after directory	920	a composite request intended to sync directories after directory
632	operations (E.g. rename). This might not work on all operating	921	operations (E.g. rename). This might not work on all operating
633	systems or have any specific effect, but usually it makes sure that	922	systems or have any specific effect, but usually it makes sure that
634	directory changes get written to disc. It works for anything that	923	directory changes get written to disc. It works for anything that
…		…
640	Passes 0 when everything went ok, and -1 on error.	929	Passes 0 when everything went ok, and -1 on error.
641		930
642	aio_msync $scalar, $offset = 0, $length = undef, flags = 0,	931	aio_msync $scalar, $offset = 0, $length = undef, flags = 0,
643	$callback->($status)	932	$callback->($status)
644	This is a rather advanced IO::AIO call, which only works on	933	This is a rather advanced IO::AIO call, which only works on
645	mmap(2)ed scalars (see the Sys::Mmap or Mmap modules for details on	934	mmap(2)ed scalars (see the "IO::AIO::mmap" function, although it
		935	also works on data scalars managed by the Sys::Mmap or Mmap modules,
646	this, note that the scalar must only be modified in-place while an	936	note that the scalar must only be modified in-place while an aio
647	aio operation is pending on it).	937	operation is pending on it).
648		938
649	It calls the "msync" function of your OS, if available, with the	939	It calls the "msync" function of your OS, if available, with the
650	memory area starting at $offset in the string and ending $length	940	memory area starting at $offset in the string and ending $length
651	bytes later. If $length is negative, counts from the end, and if	941	bytes later. If $length is negative, counts from the end, and if
652	$length is "undef", then it goes till the end of the string. The	942	$length is "undef", then it goes till the end of the string. The
…		…
660		950
661	It touches (reads or writes) all memory pages in the specified range	951	It touches (reads or writes) all memory pages in the specified range
662	inside the scalar. All caveats and parameters are the same as for	952	inside the scalar. All caveats and parameters are the same as for
663	"aio_msync", above, except for flags, which must be either 0 (which	953	"aio_msync", above, except for flags, which must be either 0 (which
664	reads all pages and ensures they are instantiated) or	954	reads all pages and ensures they are instantiated) or
665	"IO::AIO::MT_MODIFY", which modifies the memory page s(by reading	955	"IO::AIO::MT_MODIFY", which modifies the memory pages (by reading
666	and writing an octet from it, which dirties the page).	956	and writing an octet from it, which dirties the page).
		957
		958	aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
		959	This is a rather advanced IO::AIO call, which works best on
		960	mmap(2)ed scalars.
		961
		962	It reads in all the pages of the underlying storage into memory (if
		963	any) and locks them, so they are not getting swapped/paged out or
		964	removed.
		965
		966	If $length is undefined, then the scalar will be locked till the
		967	end.
		968
		969	On systems that do not implement "mlock", this function returns -1
		970	and sets errno to "ENOSYS".
		971
		972	Note that the corresponding "munlock" is synchronous and is
		973	documented under "MISCELLANEOUS FUNCTIONS".
		974
		975	Example: open a file, mmap and mlock it - both will be undone when
		976	$data gets destroyed.
		977
		978	open my $fh, "<", $path or die "$path: $!";
		979	my $data;
		980	IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;
		981	aio_mlock $data; # mlock in background
		982
		983	aio_mlockall $flags, $callback->($status)
		984	Calls the "mlockall" function with the given $flags (a combination
		985	of "IO::AIO::MCL_CURRENT" and "IO::AIO::MCL_FUTURE").
		986
		987	On systems that do not implement "mlockall", this function returns
		988	-1 and sets errno to "ENOSYS".
		989
		990	Note that the corresponding "munlockall" is synchronous and is
		991	documented under "MISCELLANEOUS FUNCTIONS".
		992
		993	Example: asynchronously lock all current and future pages into
		994	memory.
		995
		996	aio_mlockall IO::AIO::MCL_FUTURE;
		997
		998	aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
		999	Queries the extents of the given file (by calling the Linux "FIEMAP"
		1000	ioctl, see <http://cvs.schmorp.de/IO-AIO/doc/fiemap.txt> for
		1001	details). If the ioctl is not available on your OS, then this
		1002	request will fail with "ENOSYS".
		1003
		1004	$start is the starting offset to query extents for, $length is the
		1005	size of the range to query - if it is "undef", then the whole file
		1006	will be queried.
		1007
		1008	$flags is a combination of flags ("IO::AIO::FIEMAP_FLAG_SYNC" or
		1009	"IO::AIO::FIEMAP_FLAG_XATTR" - "IO::AIO::FIEMAP_FLAGS_COMPAT" is
		1010	also exported), and is normally 0 or "IO::AIO::FIEMAP_FLAG_SYNC" to
		1011	query the data portion.
		1012
		1013	$count is the maximum number of extent records to return. If it is
		1014	"undef", then IO::AIO queries all extents of the range. As a very
		1015	special case, if it is 0, then the callback receives the number of
		1016	extents instead of the extents themselves (which is unreliable, see
		1017	below).
		1018
		1019	If an error occurs, the callback receives no arguments. The special
		1020	"errno" value "IO::AIO::EBADR" is available to test for flag errors.
		1021
		1022	Otherwise, the callback receives an array reference with extent
		1023	structures. Each extent structure is an array reference itself, with
		1024	the following members:
		1025
		1026	[$logical, $physical, $length, $flags]
		1027
		1028	Flags is any combination of the following flag values (typically
		1029	either 0 or "IO::AIO::FIEMAP_EXTENT_LAST" (1)):
		1030
		1031	"IO::AIO::FIEMAP_EXTENT_LAST", "IO::AIO::FIEMAP_EXTENT_UNKNOWN",
		1032	"IO::AIO::FIEMAP_EXTENT_DELALLOC", "IO::AIO::FIEMAP_EXTENT_ENCODED",
		1033	"IO::AIO::FIEMAP_EXTENT_DATA_ENCRYPTED",
		1034	"IO::AIO::FIEMAP_EXTENT_NOT_ALIGNED",
		1035	"IO::AIO::FIEMAP_EXTENT_DATA_INLINE",
		1036	"IO::AIO::FIEMAP_EXTENT_DATA_TAIL",
		1037	"IO::AIO::FIEMAP_EXTENT_UNWRITTEN", "IO::AIO::FIEMAP_EXTENT_MERGED"
		1038	or "IO::AIO::FIEMAP_EXTENT_SHARED".
		1039
		1040	At the time of this writing (Linux 3.2), this requets is unreliable
		1041	unless $count is "undef", as the kernel has all sorts of bugs
		1042	preventing it to return all extents of a range for files with large
		1043	number of extents. The code works around all these issues if $count
		1044	is undef.
667		1045
668	aio_group $callback->(...)	1046	aio_group $callback->(...)
669	This is a very special aio request: Instead of doing something, it	1047	This is a very special aio request: Instead of doing something, it
670	is a container for other aio requests, which is useful if you want	1048	is a container for other aio requests, which is useful if you want
671	to bundle many requests into a single, composite, request with a	1049	to bundle many requests into a single, composite, request with a
…		…
705	While it is theoretically handy to have simple I/O scheduling	1083	While it is theoretically handy to have simple I/O scheduling
706	requests like sleep and file handle readable/writable, the overhead	1084	requests like sleep and file handle readable/writable, the overhead
707	this creates is immense (it blocks a thread for a long time) so do	1085	this creates is immense (it blocks a thread for a long time) so do
708	not use this function except to put your application under	1086	not use this function except to put your application under
709	artificial I/O pressure.	1087	artificial I/O pressure.
		1088
		1089	IO::AIO::WD - multiple working directories
		1090	Your process only has one current working directory, which is used by
		1091	all threads. This makes it hard to use relative paths (some other
		1092	component could call "chdir" at any time, and it is hard to control when
		1093	the path will be used by IO::AIO).
		1094
		1095	One solution for this is to always use absolute paths. This usually
		1096	works, but can be quite slow (the kernel has to walk the whole path on
		1097	every access), and can also be a hassle to implement.
		1098
		1099	Newer POSIX systems have a number of functions (openat, fdopendir,
		1100	futimensat and so on) that make it possible to specify working
		1101	directories per operation.
		1102
		1103	For portability, and because the clowns who "designed", or shall I
		1104	write, perpetrated this new interface were obviously half-drunk, this
		1105	abstraction cannot be perfect, though.
		1106
		1107	IO::AIO allows you to convert directory paths into a so-called
		1108	IO::AIO::WD object. This object stores the canonicalised, absolute
		1109	version of the path, and on systems that allow it, also a directory file
		1110	descriptor.
		1111
		1112	Everywhere where a pathname is accepted by IO::AIO (e.g. in "aio_stat"
		1113	or "aio_unlink"), one can specify an array reference with an IO::AIO::WD
		1114	object and a pathname instead (or the IO::AIO::WD object alone, which
		1115	gets interpreted as "[$wd, "."]"). If the pathname is absolute, the
		1116	IO::AIO::WD object is ignored, otherwise the pathname is resolved
		1117	relative to that IO::AIO::WD object.
		1118
		1119	For example, to get a wd object for /etc and then stat passwd inside,
		1120	you would write:
		1121
		1122	aio_wd "/etc", sub {
		1123	my $etcdir = shift;
		1124
		1125	# although $etcdir can be undef on error, there is generally no reason
		1126	# to check for errors here, as aio_stat will fail with ENOENT
		1127	# when $etcdir is undef.
		1128
		1129	aio_stat [$etcdir, "passwd"], sub {
		1130	# yay
		1131	};
		1132	};
		1133
		1134	That "aio_wd" is a request and not a normal function shows that creating
		1135	an IO::AIO::WD object is itself a potentially blocking operation, which
		1136	is why it is done asynchronously.
		1137
		1138	To stat the directory obtained with "aio_wd" above, one could write
		1139	either of the following three request calls:
		1140
		1141	aio_lstat "/etc" , sub { ... # pathname as normal string
		1142	aio_lstat [$wd, "."], sub { ... # "." relative to $wd (i.e. $wd itself)
		1143	aio_lstat $wd , sub { ... # shorthand for the previous
		1144
		1145	As with normal pathnames, IO::AIO keeps a copy of the working directory
		1146	object and the pathname string, so you could write the following without
		1147	causing any issues due to $path getting reused:
		1148
		1149	my $path = [$wd, undef];
		1150
		1151	for my $name (qw(abc def ghi)) {
		1152	$path->[1] = $name;
		1153	aio_stat $path, sub {
		1154	# ...
		1155	};
		1156	}
		1157
		1158	There are some caveats: when directories get renamed (or deleted), the
		1159	pathname string doesn't change, so will point to the new directory (or
		1160	nowhere at all), while the directory fd, if available on the system,
		1161	will still point to the original directory. Most functions accepting a
		1162	pathname will use the directory fd on newer systems, and the string on
		1163	older systems. Some functions (such as realpath) will always rely on the
		1164	string form of the pathname.
		1165
		1166	So this functionality is mainly useful to get some protection against
		1167	"chdir", to easily get an absolute path out of a relative path for
		1168	future reference, and to speed up doing many operations in the same
		1169	directory (e.g. when stat'ing all files in a directory).
		1170
		1171	The following functions implement this working directory abstraction:
		1172
		1173	aio_wd $pathname, $callback->($wd)
		1174	Asynchonously canonicalise the given pathname and convert it to an
		1175	IO::AIO::WD object representing it. If possible and supported on the
		1176	system, also open a directory fd to speed up pathname resolution
		1177	relative to this working directory.
		1178
		1179	If something goes wrong, then "undef" is passwd to the callback
		1180	instead of a working directory object and $! is set appropriately.
		1181	Since passing "undef" as working directory component of a pathname
		1182	fails the request with "ENOENT", there is often no need for error
		1183	checking in the "aio_wd" callback, as future requests using the
		1184	value will fail in the expected way.
		1185
		1186	If this call isn't available because your OS lacks it or it couldn't
		1187	be detected, it will be emulated by calling "fsync" instead.
		1188
		1189	IO::AIO::CWD
		1190	This is a compiletime constant (object) that represents the process
		1191	current working directory.
		1192
		1193	Specifying this object as working directory object for a pathname is
		1194	as if the pathname would be specified directly, without a directory
		1195	object. For example, these calls are functionally identical:
		1196
		1197	aio_stat "somefile", sub { ... };
		1198	aio_stat [IO::AIO::CWD, "somefile"], sub { ... };
		1199
		1200	To recover the path associated with an IO::AIO::WD object, you can use
		1201	"aio_realpath":
		1202
		1203	aio_realpath $wd, sub {
		1204	warn "path is $_[0]\n";
		1205	};
		1206
		1207	Currently, "aio_statvfs" always, and "aio_rename" and "aio_rmdir"
		1208	sometimes, fall back to using an absolue path.
710		1209
711	IO::AIO::REQ CLASS	1210	IO::AIO::REQ CLASS
712	All non-aggregate "aio_*" functions return an object of this class when	1211	All non-aggregate "aio_*" functions return an object of this class when
713	called in non-void context.	1212	called in non-void context.
714		1213
…		…
814	Sets a feeder/generator on this group: every group can have an	1313	Sets a feeder/generator on this group: every group can have an
815	attached generator that generates requests if idle. The idea behind	1314	attached generator that generates requests if idle. The idea behind
816	this is that, although you could just queue as many requests as you	1315	this is that, although you could just queue as many requests as you
817	want in a group, this might starve other requests for a potentially	1316	want in a group, this might starve other requests for a potentially
818	long time. For example, "aio_scandir" might generate hundreds of	1317	long time. For example, "aio_scandir" might generate hundreds of
819	thousands "aio_stat" requests, delaying any later requests for a	1318	thousands of "aio_stat" requests, delaying any later requests for a
820	long time.	1319	long time.
821		1320
822	To avoid this, and allow incremental generation of requests, you can	1321	To avoid this, and allow incremental generation of requests, you can
823	instead a group and set a feeder on it that generates those	1322	instead a group and set a feeder on it that generates those
824	requests. The feed callback will be called whenever there are few	1323	requests. The feed callback will be called whenever there are few
…		…
866	results.	1365	results.
867		1366
868	See "poll_cb" for an example.	1367	See "poll_cb" for an example.
869		1368
870	IO::AIO::poll_cb	1369	IO::AIO::poll_cb
871	Process some outstanding events on the result pipe. You have to call	1370	Process some requests that have reached the result phase (i.e. they
872	this regularly. Returns 0 if all events could be processed, or -1 if	1371	have been executed but the results are not yet reported). You have
873	it returned earlier for whatever reason. Returns immediately when no	1372	to call this "regularly" to finish outstanding requests.
874	events are outstanding. The amount of events processed depends on
875	the settings of "IO::AIO::max_poll_req" and
876	"IO::AIO::max_poll_time".
877		1373
		1374	Returns 0 if all events could be processed (or there were no events
		1375	to process), or -1 if it returned earlier for whatever reason.
		1376	Returns immediately when no events are outstanding. The amount of
		1377	events processed depends on the settings of "IO::AIO::max_poll_req",
		1378	"IO::AIO::max_poll_time" and "IO::AIO::max_outstanding".
		1379
878	If not all requests were processed for whatever reason, the	1380	If not all requests were processed for whatever reason, the poll
879	filehandle will still be ready when "poll_cb" returns, so normally	1381	file descriptor will still be ready when "poll_cb" returns, so
880	you don't have to do anything special to have it called later.	1382	normally you don't have to do anything special to have it called
		1383	later.
		1384
		1385	Apart from calling "IO::AIO::poll_cb" when the event filehandle
		1386	becomes ready, it can be beneficial to call this function from loops
		1387	which submit a lot of requests, to make sure the results get
		1388	processed when they become available and not just when the loop is
		1389	finished and the event loop takes over again. This function returns
		1390	very fast when there are no outstanding requests.
881		1391
882	Example: Install an Event watcher that automatically calls	1392	Example: Install an Event watcher that automatically calls
883	IO::AIO::poll_cb with high priority (more examples can be found in	1393	IO::AIO::poll_cb with high priority (more examples can be found in
884	the SYNOPSIS section, at the top of this document):	1394	the SYNOPSIS section, at the top of this document):
885		1395
886	Event->io (fd => IO::AIO::poll_fileno,	1396	Event->io (fd => IO::AIO::poll_fileno,
887	poll => 'r', async => 1,	1397	poll => 'r', async => 1,
888	cb => \&IO::AIO::poll_cb);	1398	cb => \&IO::AIO::poll_cb);
		1399
		1400	IO::AIO::poll_wait
		1401	Wait until either at least one request is in the result phase or no
		1402	requests are outstanding anymore.
		1403
		1404	This is useful if you want to synchronously wait for some requests
		1405	to become ready, without actually handling them.
		1406
		1407	See "nreqs" for an example.
		1408
		1409	IO::AIO::poll
		1410	Waits until some requests have been handled.
		1411
		1412	Returns the number of requests processed, but is otherwise strictly
		1413	equivalent to:
		1414
		1415	IO::AIO::poll_wait, IO::AIO::poll_cb
		1416
		1417	IO::AIO::flush
		1418	Wait till all outstanding AIO requests have been handled.
		1419
		1420	Strictly equivalent to:
		1421
		1422	IO::AIO::poll_wait, IO::AIO::poll_cb
		1423	while IO::AIO::nreqs;
889		1424
890	IO::AIO::max_poll_reqs $nreqs	1425	IO::AIO::max_poll_reqs $nreqs
891	IO::AIO::max_poll_time $seconds	1426	IO::AIO::max_poll_time $seconds
892	These set the maximum number of requests (default 0, meaning	1427	These set the maximum number of requests (default 0, meaning
893	infinity) that are being processed by "IO::AIO::poll_cb" in one	1428	infinity) that are being processed by "IO::AIO::poll_cb" in one
…		…
917	# use a low priority so other tasks have priority	1452	# use a low priority so other tasks have priority
918	Event->io (fd => IO::AIO::poll_fileno,	1453	Event->io (fd => IO::AIO::poll_fileno,
919	poll => 'r', nice => 1,	1454	poll => 'r', nice => 1,
920	cb => &IO::AIO::poll_cb);	1455	cb => &IO::AIO::poll_cb);
921		1456
922	IO::AIO::poll_wait
923	If there are any outstanding requests and none of them in the result
924	phase, wait till the result filehandle becomes ready for reading
925	(simply does a "select" on the filehandle. This is useful if you
926	want to synchronously wait for some requests to finish).
927
928	See "nreqs" for an example.
929
930	IO::AIO::poll
931	Waits until some requests have been handled.
932
933	Returns the number of requests processed, but is otherwise strictly
934	equivalent to:
935
936	IO::AIO::poll_wait, IO::AIO::poll_cb
937
938	IO::AIO::flush
939	Wait till all outstanding AIO requests have been handled.
940
941	Strictly equivalent to:
942
943	IO::AIO::poll_wait, IO::AIO::poll_cb
944	while IO::AIO::nreqs;
945
946	CONTROLLING THE NUMBER OF THREADS	1457	CONTROLLING THE NUMBER OF THREADS
947	IO::AIO::min_parallel $nthreads	1458	IO::AIO::min_parallel $nthreads
948	Set the minimum number of AIO threads to $nthreads. The current	1459	Set the minimum number of AIO threads to $nthreads. The current
949	default is 8, which means eight asynchronous operations can execute	1460	default is 8, which means eight asynchronous operations can execute
950	concurrently at any one time (the number of outstanding requests,	1461	concurrently at any one time (the number of outstanding requests,
…		…
979		1490
980	Under normal circumstances you don't need to call this function.	1491	Under normal circumstances you don't need to call this function.
981		1492
982	IO::AIO::max_idle $nthreads	1493	IO::AIO::max_idle $nthreads
983	Limit the number of threads (default: 4) that are allowed to idle	1494	Limit the number of threads (default: 4) that are allowed to idle
984	(i.e., threads that did not get a request to process within 10	1495	(i.e., threads that did not get a request to process within the idle
985	seconds). That means if a thread becomes idle while $nthreads other	1496	timeout (default: 10 seconds). That means if a thread becomes idle
986	threads are also idle, it will free its resources and exit.	1497	while $nthreads other threads are also idle, it will free its
		1498	resources and exit.
987		1499
988	This is useful when you allow a large number of threads (e.g. 100 or	1500	This is useful when you allow a large number of threads (e.g. 100 or
989	1000) to allow for extremely high load situations, but want to free	1501	1000) to allow for extremely high load situations, but want to free
990	resources under normal circumstances (1000 threads can easily	1502	resources under normal circumstances (1000 threads can easily
991	consume 30MB of RAM).	1503	consume 30MB of RAM).
992		1504
993	The default is probably ok in most situations, especially if thread	1505	The default is probably ok in most situations, especially if thread
994	creation is fast. If thread creation is very slow on your system you	1506	creation is fast. If thread creation is very slow on your system you
995	might want to use larger values.	1507	might want to use larger values.
996		1508
		1509	IO::AIO::idle_timeout $seconds
		1510	Sets the minimum idle timeout (default 10) after which worker
		1511	threads are allowed to exit. SEe "IO::AIO::max_idle".
		1512
997	IO::AIO::max_outstanding $maxreqs	1513	IO::AIO::max_outstanding $maxreqs
		1514	Sets the maximum number of outstanding requests to $nreqs. If you do
		1515	queue up more than this number of requests, the next call to
		1516	"IO::AIO::poll_cb" (and other functions calling "poll_cb", such as
		1517	"IO::AIO::flush" or "IO::AIO::poll") will block until the limit is
		1518	no longer exceeded.
		1519
		1520	In other words, this setting does not enforce a queue limit, but can
		1521	be used to make poll functions block if the limit is exceeded.
		1522
998	This is a very bad function to use in interactive programs because	1523	This is a very bad function to use in interactive programs because
999	it blocks, and a bad way to reduce concurrency because it is	1524	it blocks, and a bad way to reduce concurrency because it is
1000	inexact: Better use an "aio_group" together with a feed callback.	1525	inexact: Better use an "aio_group" together with a feed callback.
1001		1526
1002	Sets the maximum number of outstanding requests to $nreqs. If you do	1527	It's main use is in scripts without an event loop - when you want to
1003	queue up more than this number of requests, the next call to the	1528	stat a lot of files, you can write somehting like this:
1004	"poll_cb" (and "poll_some" and other functions calling "poll_cb")
1005	function will block until the limit is no longer exceeded.
1006		1529
1007	The default value is very large, so there is no practical limit on	1530	IO::AIO::max_outstanding 32;
		1531
		1532	for my $path (...) {
		1533	aio_stat $path , ...;
		1534	IO::AIO::poll_cb;
		1535	}
		1536
		1537	IO::AIO::flush;
		1538
		1539	The call to "poll_cb" inside the loop will normally return
		1540	instantly, but as soon as more thna 32 reqeusts are in-flight, it
		1541	will block until some requests have been handled. This keeps the
		1542	loop from pushing a large number of "aio_stat" requests onto the
		1543	queue.
		1544
		1545	The default value for "max_outstanding" is very large, so there is
1008	the number of outstanding requests.	1546	no practical limit on the number of outstanding requests.
1009
1010	You can still queue as many requests as you want. Therefore,
1011	"max_outstanding" is mainly useful in simple scripts (with low
1012	values) or as a stop gap to shield against fatal memory overflow
1013	(with large values).
1014		1547
1015	STATISTICAL INFORMATION	1548	STATISTICAL INFORMATION
1016	IO::AIO::nreqs	1549	IO::AIO::nreqs
1017	Returns the number of requests currently in the ready, execute or	1550	Returns the number of requests currently in the ready, execute or
1018	pending states (i.e. for which their callback has not been invoked	1551	pending states (i.e. for which their callback has not been invoked
…		…
1042	set to non-blocking operations).	1575	set to non-blocking operations).
1043		1576
1044	Returns the number of bytes copied, or -1 on error.	1577	Returns the number of bytes copied, or -1 on error.
1045		1578
1046	IO::AIO::fadvise $fh, $offset, $len, $advice	1579	IO::AIO::fadvise $fh, $offset, $len, $advice
1047	Simply calls the "posix_fadvise" function (see it's manpage for	1580	Simply calls the "posix_fadvise" function (see its manpage for
1048	details). The following advice constants are avaiable:	1581	details). The following advice constants are available:
1049	"IO::AIO::FADV_NORMAL", "IO::AIO::FADV_SEQUENTIAL",	1582	"IO::AIO::FADV_NORMAL", "IO::AIO::FADV_SEQUENTIAL",
1050	"IO::AIO::FADV_RANDOM", "IO::AIO::FADV_NOREUSE",	1583	"IO::AIO::FADV_RANDOM", "IO::AIO::FADV_NOREUSE",
1051	"IO::AIO::FADV_WILLNEED", "IO::AIO::FADV_DONTNEED".	1584	"IO::AIO::FADV_WILLNEED", "IO::AIO::FADV_DONTNEED".
1052		1585
1053	On systems that do not implement "posix_fadvise", this function	1586	On systems that do not implement "posix_fadvise", this function
1054	returns ENOSYS, otherwise the return value of "posix_fadvise".	1587	returns ENOSYS, otherwise the return value of "posix_fadvise".
1055		1588
		1589	IO::AIO::madvise $scalar, $offset, $len, $advice
		1590	Simply calls the "posix_madvise" function (see its manpage for
		1591	details). The following advice constants are available:
		1592	"IO::AIO::MADV_NORMAL", "IO::AIO::MADV_SEQUENTIAL",
		1593	"IO::AIO::MADV_RANDOM", "IO::AIO::MADV_WILLNEED",
		1594	"IO::AIO::MADV_DONTNEED".
		1595
		1596	On systems that do not implement "posix_madvise", this function
		1597	returns ENOSYS, otherwise the return value of "posix_madvise".
		1598
		1599	IO::AIO::mprotect $scalar, $offset, $len, $protect
		1600	Simply calls the "mprotect" function on the preferably AIO::mmap'ed
		1601	$scalar (see its manpage for details). The following protect
		1602	constants are available: "IO::AIO::PROT_NONE", "IO::AIO::PROT_READ",
		1603	"IO::AIO::PROT_WRITE", "IO::AIO::PROT_EXEC".
		1604
		1605	On systems that do not implement "mprotect", this function returns
		1606	ENOSYS, otherwise the return value of "mprotect".
		1607
		1608	IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
		1609	Memory-maps a file (or anonymous memory range) and attaches it to
		1610	the given $scalar, which will act like a string scalar. Returns true
		1611	on success, and false otherwise.
		1612
		1613	The only operations allowed on the scalar are "substr"/"vec" that
		1614	don't change the string length, and most read-only operations such
		1615	as copying it or searching it with regexes and so on.
		1616
		1617	Anything else is unsafe and will, at best, result in memory leaks.
		1618
		1619	The memory map associated with the $scalar is automatically removed
		1620	when the $scalar is destroyed, or when the "IO::AIO::mmap" or
		1621	"IO::AIO::munmap" functions are called.
		1622
		1623	This calls the "mmap"(2) function internally. See your system's
		1624	manual page for details on the $length, $prot and $flags parameters.
		1625
		1626	The $length must be larger than zero and smaller than the actual
		1627	filesize.
		1628
		1629	$prot is a combination of "IO::AIO::PROT_NONE",
		1630	"IO::AIO::PROT_EXEC", "IO::AIO::PROT_READ" and/or
		1631	"IO::AIO::PROT_WRITE",
		1632
		1633	$flags can be a combination of "IO::AIO::MAP_SHARED" or
		1634	"IO::AIO::MAP_PRIVATE", or a number of system-specific flags (when
		1635	not available, the are defined as 0): "IO::AIO::MAP_ANONYMOUS"
		1636	(which is set to "MAP_ANON" if your system only provides this
		1637	constant), "IO::AIO::MAP_HUGETLB", "IO::AIO::MAP_LOCKED",
		1638	"IO::AIO::MAP_NORESERVE", "IO::AIO::MAP_POPULATE" or
		1639	"IO::AIO::MAP_NONBLOCK"
		1640
		1641	If $fh is "undef", then a file descriptor of -1 is passed.
		1642
		1643	$offset is the offset from the start of the file - it generally must
		1644	be a multiple of "IO::AIO::PAGESIZE" and defaults to 0.
		1645
		1646	Example:
		1647
		1648	use Digest::MD5;
		1649	use IO::AIO;
		1650
		1651	open my $fh, "<verybigfile"
		1652	or die "$!";
		1653
		1654	IO::AIO::mmap my $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh
		1655	or die "verybigfile: $!";
		1656
		1657	my $fast_md5 = md5 $data;
		1658
		1659	IO::AIO::munmap $scalar
		1660	Removes a previous mmap and undefines the $scalar.
		1661
		1662	IO::AIO::munlock $scalar, $offset = 0, $length = undef
		1663	Calls the "munlock" function, undoing the effects of a previous
		1664	"aio_mlock" call (see its description for details).
		1665
		1666	IO::AIO::munlockall
		1667	Calls the "munlockall" function.
		1668
		1669	On systems that do not implement "munlockall", this function returns
		1670	ENOSYS, otherwise the return value of "munlockall".
		1671
		1672	IO::AIO::splice $r_fh, $r_off, $w_fh, $w_off, $length, $flags
		1673	Calls the GNU/Linux splice(2) syscall, if available. If $r_off or
		1674	$w_off are "undef", then "NULL" is passed for these, otherwise they
		1675	should be the file offset.
		1676
		1677	$r_fh and $w_fh should not refer to the same file, as splice might
		1678	silently corrupt the data in this case.
		1679
		1680	The following symbol flag values are available:
		1681	"IO::AIO::SPLICE_F_MOVE", "IO::AIO::SPLICE_F_NONBLOCK",
		1682	"IO::AIO::SPLICE_F_MORE" and "IO::AIO::SPLICE_F_GIFT".
		1683
		1684	See the splice(2) manpage for details.
		1685
		1686	IO::AIO::tee $r_fh, $w_fh, $length, $flags
		1687	Calls the GNU/Linux tee(2) syscall, see it's manpage and the
		1688	description for "IO::AIO::splice" above for details.
		1689
		1690	EVENT LOOP INTEGRATION
		1691	It is recommended to use AnyEvent::AIO to integrate IO::AIO
		1692	automatically into many event loops:
		1693
		1694	# AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...)
		1695	use AnyEvent::AIO;
		1696
		1697	You can also integrate IO::AIO manually into many event loops, here are
		1698	some examples of how to do this:
		1699
		1700	# EV integration
		1701	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
		1702
		1703	# Event integration
		1704	Event->io (fd => IO::AIO::poll_fileno,
		1705	poll => 'r',
		1706	cb => \&IO::AIO::poll_cb);
		1707
		1708	# Glib/Gtk2 integration
		1709	add_watch Glib::IO IO::AIO::poll_fileno,
		1710	in => sub { IO::AIO::poll_cb; 1 };
		1711
		1712	# Tk integration
		1713	Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
		1714	readable => \&IO::AIO::poll_cb);
		1715
		1716	# Danga::Socket integration
		1717	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
		1718	\&IO::AIO::poll_cb);
		1719
1056	FORK BEHAVIOUR	1720	FORK BEHAVIOUR
1057	This module should do "the right thing" when the process using it forks:	1721	Usage of pthreads in a program changes the semantics of fork
		1722	considerably. Specifically, only async-safe functions can be called
		1723	after fork. Perl doesn't know about this, so in general, you cannot call
		1724	fork with defined behaviour in perl if pthreads are involved. IO::AIO
		1725	uses pthreads, so this applies, but many other extensions and (for
		1726	inexplicable reasons) perl itself often is linked against pthreads, so
		1727	this limitation applies to quite a lot of perls.
1058		1728
1059	Before the fork, IO::AIO enters a quiescent state where no requests can	1729	This module no longer tries to fight your OS, or POSIX. That means
1060	be added in other threads and no results will be processed. After the	1730	IO::AIO only works in the process that loaded it. Forking is fully
1061	fork the parent simply leaves the quiescent state and continues	1731	supported, but using IO::AIO in the child is not.
1062	request/result processing, while the child frees the request/result
1063	queue (so that the requests started before the fork will only be handled
1064	in the parent). Threads will be started on demand until the limit set in
1065	the parent process has been reached again.
1066		1732
1067	In short: the parent will, after a short pause, continue as if fork had	1733	You might get around by not using IO::AIO before (or after) forking.
1068	not been called, while the child will act as if IO::AIO has not been	1734	You could also try to call the IO::AIO::reinit function in the child:
1069	used yet.	1735
		1736	IO::AIO::reinit
		1737	Abandons all current requests and I/O threads and simply
		1738	reinitialises all data structures. This is not an operation
		1739	supported by any standards, but happens to work on GNU/Linux and
		1740	some newer BSD systems.
		1741
		1742	The only reasonable use for this function is to call it after
		1743	forking, if "IO::AIO" was used in the parent. Calling it while
		1744	IO::AIO is active in the process will result in undefined behaviour.
		1745	Calling it at any time will also result in any undefined (by POSIX)
		1746	behaviour.
1070		1747
1071	MEMORY USAGE	1748	MEMORY USAGE
1072	Per-request usage:	1749	Per-request usage:
1073		1750
1074	Each aio request uses - depending on your architecture - around 100-200	1751	Each aio request uses - depending on your architecture - around 100-200

Diff Legend

-–
+Removed lines
-+
+Added lines
-<
+Changed lines
->
+Changed lines

Comparing IO-AIO/README (file contents): Revision 1.41 by root, Sat Jan 2 14:24:32 2010 UTC vs. Revision 1.54 by root, Sun Jan 6 11:48:14 2013 UTC

Diff Legend

Comparing IO-AIO/README (file contents):
Revision 1.41 by root, Sat Jan 2 14:24:32 2010 UTC vs.
Revision 1.54 by root, Sun Jan 6 11:48:14 2013 UTC