[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 1.54 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
…		…
72		72
73	# register the IO::AIO callback with EV	73	# register the IO::AIO callback with EV
74	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;
75		75
76	# queue the request to open /etc/passwd	76	# queue the request to open /etc/passwd
77	aio_open "/etc/passwd", O_RDONLY, 0, sub {	77	aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
78	my $fh = shift	78	my $fh = shift
79	or die "error while opening: $!";	79	or die "error while opening: $!";
80		80
81	# stat'ing filehandles is generally non-blocking	81	# stat'ing filehandles is generally non-blocking
82	my $size = -s $fh;	82	my $size = -s $fh;
…		…
146	the actual aio request is severed and calling its methods will	146	the actual aio request is severed and calling its methods will
147	either do nothing or result in a runtime error).	147	either do nothing or result in a runtime error).
148		148
149	FUNCTIONS	149	FUNCTIONS
150	QUICK OVERVIEW	150	QUICK OVERVIEW
151	This section simply lists the prototypes of the most important functions	151	This section simply lists the prototypes most of the functions for quick
152	for quick reference. See the following sections for function-by-function	152	reference. See the following sections for function-by-function
153	documentation.	153	documentation.
154		154
		155	aio_wd $pathname, $callback->($wd)
155	aio_open $pathname, $flags, $mode, $callback->($fh)	156	aio_open $pathname, $flags, $mode, $callback->($fh)
156	aio_close $fh, $callback->($status)	157	aio_close $fh, $callback->($status)
		158	aio_seek $fh,$offset,$whence, $callback->($offs)
157	aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	159	aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
158	aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	160	aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
159	aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)	161	aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
160	aio_readahead $fh,$offset,$length, $callback->($retval)	162	aio_readahead $fh,$offset,$length, $callback->($retval)
161	aio_stat $fh_or_path, $callback->($status)	163	aio_stat $fh_or_path, $callback->($status)
162	aio_lstat $fh, $callback->($status)	164	aio_lstat $fh, $callback->($status)
163	aio_statvfs $fh_or_path, $callback->($statvfs)	165	aio_statvfs $fh_or_path, $callback->($statvfs)
164	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)	166	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
165	aio_chown $fh_or_path, $uid, $gid, $callback->($status)	167	aio_chown $fh_or_path, $uid, $gid, $callback->($status)
		168	aio_chmod $fh_or_path, $mode, $callback->($status)
166	aio_truncate $fh_or_path, $offset, $callback->($status)	169	aio_truncate $fh_or_path, $offset, $callback->($status)
167	aio_chmod $fh_or_path, $mode, $callback->($status)	170	aio_allocate $fh, $mode, $offset, $len, $callback->($status)
		171	aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
168	aio_unlink $pathname, $callback->($status)	172	aio_unlink $pathname, $callback->($status)
169	aio_mknod $path, $mode, $dev, $callback->($status)	173	aio_mknod $pathname, $mode, $dev, $callback->($status)
170	aio_link $srcpath, $dstpath, $callback->($status)	174	aio_link $srcpath, $dstpath, $callback->($status)
171	aio_symlink $srcpath, $dstpath, $callback->($status)	175	aio_symlink $srcpath, $dstpath, $callback->($status)
172	aio_readlink $path, $callback->($link)	176	aio_readlink $pathname, $callback->($link)
		177	aio_realpath $pathname, $callback->($link)
173	aio_rename $srcpath, $dstpath, $callback->($status)	178	aio_rename $srcpath, $dstpath, $callback->($status)
174	aio_mkdir $pathname, $mode, $callback->($status)	179	aio_mkdir $pathname, $mode, $callback->($status)
175	aio_rmdir $pathname, $callback->($status)	180	aio_rmdir $pathname, $callback->($status)
176	aio_readdir $pathname, $callback->($entries)	181	aio_readdir $pathname, $callback->($entries)
177	aio_readdirx $pathname, $flags, $callback->($entries, $flags)	182	aio_readdirx $pathname, $flags, $callback->($entries, $flags)
178	IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST	183	IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST
179	IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN	184	IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN
		185	aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
180	aio_load $path, $data, $callback->($status)	186	aio_load $pathname, $data, $callback->($status)
181	aio_copy $srcpath, $dstpath, $callback->($status)	187	aio_copy $srcpath, $dstpath, $callback->($status)
182	aio_move $srcpath, $dstpath, $callback->($status)	188	aio_move $srcpath, $dstpath, $callback->($status)
183	aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
184	aio_rmtree $path, $callback->($status)	189	aio_rmtree $pathname, $callback->($status)
185	aio_sync $callback->($status)	190	aio_sync $callback->($status)
		191	aio_syncfs $fh, $callback->($status)
186	aio_fsync $fh, $callback->($status)	192	aio_fsync $fh, $callback->($status)
187	aio_fdatasync $fh, $callback->($status)	193	aio_fdatasync $fh, $callback->($status)
188	aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)	194	aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
189	aio_pathsync $path, $callback->($status)	195	aio_pathsync $pathname, $callback->($status)
190	aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)	196	aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
191	aio_mtouch $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)
192	aio_group $callback->(...)	200	aio_group $callback->(...)
193	aio_nop $callback->()	201	aio_nop $callback->()
194		202
195	$prev_pri = aioreq_pri [$pri]	203	$prev_pri = aioreq_pri [$pri]
196	aioreq_nice $pri_adjust	204	aioreq_nice $pri_adjust
…		…
202	IO::AIO::max_poll_reqs $nreqs	210	IO::AIO::max_poll_reqs $nreqs
203	IO::AIO::max_poll_time $seconds	211	IO::AIO::max_poll_time $seconds
204	IO::AIO::min_parallel $nthreads	212	IO::AIO::min_parallel $nthreads
205	IO::AIO::max_parallel $nthreads	213	IO::AIO::max_parallel $nthreads
206	IO::AIO::max_idle $nthreads	214	IO::AIO::max_idle $nthreads
		215	IO::AIO::idle_timeout $seconds
207	IO::AIO::max_outstanding $maxreqs	216	IO::AIO::max_outstanding $maxreqs
208	IO::AIO::nreqs	217	IO::AIO::nreqs
209	IO::AIO::nready	218	IO::AIO::nready
210	IO::AIO::npending	219	IO::AIO::npending
211		220
212	IO::AIO::sendfile $ofh, $ifh, $offset, $count	221	IO::AIO::sendfile $ofh, $ifh, $offset, $count
213	IO::AIO::fadvise $fh, $offset, $len, $advice	222	IO::AIO::fadvise $fh, $offset, $len, $advice
214	IO::AIO::mlockall $flags	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
215	IO::AIO::munlockall	228	IO::AIO::munlockall
216		229
217	AIO REQUEST FUNCTIONS	230	API NOTES
218	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
219	with the same name (sans "aio_"). The arguments are similar or	232	with the same name (sans "aio_"). The arguments are similar or
220	identical, and they all accept an additional (and optional) $callback	233	identical, and they all accept an additional (and optional) $callback
221	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
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.	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".
225		243
226	All functions expecting a filehandle keep a copy of the filehandle	244	All functions expecting a filehandle keep a copy of the filehandle
227	internally until the request has finished.	245	internally until the request has finished.
228		246
229	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
230	further manipulation of those requests while they are in-flight.	248	further manipulation of those requests while they are in-flight.
231		249
232	The pathnames you pass to these routines must be absolute and encoded	250	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	251	reason for this is that at the time the request is being executed, the
234	being executed, the current working directory could have changed.	252	current working directory could have changed. Alternatively, you can
235	Alternatively, you can make sure that you never change the current	253	make sure that you never change the current working directory anywhere
236	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.
237		258
238	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
239	pass in filenames you got from outside (command line, readdir etc.)	260	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	261	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	262	Encode module and encode your pathnames to the locale (or other)
242	the user environment, d) use Glib::filename_from_unicode on unicode	263	encoding in effect in the user environment, d) use
243	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
244	contents.	265	else to ensure your scalar has the correct contents.
245		266
246	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
247	handles correctly whether it is set or not.	268	handles correctly whether it is set or not.
248		269
		270	AIO REQUEST FUNCTIONS
249	$prev_pri = aioreq_pri [$pri]	271	$prev_pri = aioreq_pri [$pri]
250	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
251	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.
252		274
253	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
…		…
275	Similar to "aioreq_pri", but subtracts the given value from the	297	Similar to "aioreq_pri", but subtracts the given value from the
276	current priority, so the effect is cumulative.	298	current priority, so the effect is cumulative.
277		299
278	aio_open $pathname, $flags, $mode, $callback->($fh)	300	aio_open $pathname, $flags, $mode, $callback->($fh)
279	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
280	newly created filehandle for the file.	302	newly created filehandle for the file (or "undef" in case of an
		303	error).
281		304
282	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,
283	above, for an explanation.	306	above, for an explanation.
284		307
285	The $flags argument is a bitmask. See the "Fcntl" module for a list.	308	The $flags argument is a bitmask. See the "Fcntl" module for a list.
…		…
292	will be modified by the umask in effect then the request is being	315	will be modified by the umask in effect then the request is being
293	executed, so better never change the umask.	316	executed, so better never change the umask.
294		317
295	Example:	318	Example:
296		319
297	aio_open "/etc/passwd", O_RDONLY, 0, sub {	320	aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
298	if ($_[0]) {	321	if ($_[0]) {
299	print "open successful, fh is $_[0]\n";	322	print "open successful, fh is $_[0]\n";
300	...	323	...
301	} else {	324	} else {
302	die "open failed: $!\n";	325	die "open failed: $!\n";
303	}	326	}
304	};	327	};
305		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
306	aio_close $fh, $callback->($status)	338	aio_close $fh, $callback->($status)
307	Asynchronously close a file and call the callback with the result	339	Asynchronously close a file and call the callback with the result
308	code.	340	code.
309		341
310	Unfortunately, you can't do this to perl. Perl insists very	342	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	347	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).	348	a pipe (the pipe fd will be created on demand and will be cached).
317		349
318	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
319	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".
320		371
321	aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	372	aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
322	aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	373	aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
323	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
324	$offset into the scalar given by $data and offset $dataoffset and	375	$offset into the scalar given by $data and offset $dataoffset and
…		…
353	aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)	404	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	405	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	406	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	407	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	408	more than one "aio_sendfile" per $out_fh, as they will interfere
358	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.
359		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
360	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
361	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
362	to a socket, and $in_fh should refer to an mmap'able file.	431	to a socket, and $in_fh should refer to an mmap'able file.
363		432
364	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",
365	"ENOTSUP", "EOPNOTSUPP", "EAFNOSUPPORT", "EPROTOTYPE" or "ENOTSOCK",	434	"EINVAL", "ENOTSUP", "EOPNOTSUPP", "EAFNOSUPPORT", "EPROTOTYPE" or
366	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
367	filehandle regardless of the limitations of the operating system.	436	any type of filehandle regardless of the limitations of the
		437	operating system.
368		438
369	Please note, however, that "aio_sendfile" can read more bytes from	439	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	440	hacked together in a hurry to improve benchmark numbers) tend to be
371	bytes have been read from "aio_sendfile" alone, as "aio_sendfile"	441	rather buggy on many systems, this implementation tries to work
372	only provides the number of bytes written to $out_fh. Only if the	442	around some known bugs in Linux and FreeBSD kernels (probably
373	result value equals $length one can assume that $length bytes have	443	others, too), but that might fail, so you really really should check
374	been read.	444	the return value of "aio_sendfile" - fewre bytes than expected might
		445	have been transferred.
375		446
376	aio_readahead $fh,$offset,$length, $callback->($retval)	447	aio_readahead $fh,$offset,$length, $callback->($retval)
377	"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
378	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
379	$offset argument specifies the starting point from which data is to	450	$offset argument specifies the starting point from which data is to
…		…
399		470
400	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
401	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
402	silently truncated unless perl itself is compiled with large file	473	silently truncated unless perl itself is compiled with large file
403	support.	474	support.
		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".
404		484
405	Example: Print the length of /etc/passwd:	485	Example: Print the length of /etc/passwd:
406		486
407	aio_stat "/etc/passwd", sub {	487	aio_stat "/etc/passwd", sub {
408	$_[0] and die "stat failed: $!";	488	$_[0] and die "stat failed: $!";
…		…
450	namemax => 255,	530	namemax => 255,
451	frsize => 1024,	531	frsize => 1024,
452	fsid => 1810	532	fsid => 1810
453	}	533	}
454		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
455	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)	617	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
456	Works like perl's "utime" function (including the special case of	618	Works like perl's "utime" function (including the special case of
457	$atime and $mtime being undef). Fractional times are supported if	619	$atime and $mtime being undef). Fractional times are supported if
458	the underlying syscalls support them.	620	the underlying syscalls support them.
459		621
…		…
481	aio_chown "path", 0, undef;	643	aio_chown "path", 0, undef;
482		644
483	aio_truncate $fh_or_path, $offset, $callback->($status)	645	aio_truncate $fh_or_path, $offset, $callback->($status)
484	Works like truncate(2) or ftruncate(2).	646	Works like truncate(2) or ftruncate(2).
485		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
486	aio_chmod $fh_or_path, $mode, $callback->($status)	662	aio_chmod $fh_or_path, $mode, $callback->($status)
487	Works like perl's "chmod" function.	663	Works like perl's "chmod" function.
488		664
489	aio_unlink $pathname, $callback->($status)	665	aio_unlink $pathname, $callback->($status)
490	Asynchronously unlink (delete) a file and call the callback with the	666	Asynchronously unlink (delete) a file and call the callback with the
491	result code.	667	result code.
492		668
493	aio_mknod $path, $mode, $dev, $callback->($status)	669	aio_mknod $pathname, $mode, $dev, $callback->($status)
494	[EXPERIMENTAL]	670	[EXPERIMENTAL]
495		671
496	Asynchronously create a device node (or fifo). See mknod(2).	672	Asynchronously create a device node (or fifo). See mknod(2).
497		673
498	The only (POSIX-) portable way of calling this function is:	674	The only (POSIX-) portable way of calling this function is:
499		675
500	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.
501		680
502	aio_link $srcpath, $dstpath, $callback->($status)	681	aio_link $srcpath, $dstpath, $callback->($status)
503	Asynchronously create a new link to the existing object at $srcpath	682	Asynchronously create a new link to the existing object at $srcpath
504	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.
505		684
506	aio_symlink $srcpath, $dstpath, $callback->($status)	685	aio_symlink $srcpath, $dstpath, $callback->($status)
507	Asynchronously create a new symbolic link to the existing object at	686	Asynchronously create a new symbolic link to the existing object at
508	$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
509	code.	688	code.
510		689
511	aio_readlink $path, $callback->($link)	690	aio_readlink $pathname, $callback->($link)
512	Asynchronously read the symlink specified by $path and pass it to	691	Asynchronously read the symlink specified by $path and pass it to
513	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
514	the callback.	693	the callback.
515		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
516	aio_rename $srcpath, $dstpath, $callback->($status)	703	aio_rename $srcpath, $dstpath, $callback->($status)
517	Asynchronously rename the object at $srcpath to $dstpath, just as	704	Asynchronously rename the object at $srcpath to $dstpath, just as
518	rename(2) and call the callback with the result code.	705	rename(2) and call the callback with the result code.
		706
		707	On systems that support the AIO::WD working directory abstraction
		708	natively, the case "[$wd, "."]" as $srcpath is specialcased -
		709	instead of failing, "rename" is called on the absolute path of $wd.
519		710
520	aio_mkdir $pathname, $mode, $callback->($status)	711	aio_mkdir $pathname, $mode, $callback->($status)
521	Asynchronously mkdir (create) a directory and call the callback with	712	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	713	the result code. $mode will be modified by the umask at the time the
523	request is executed, so do not change your umask.	714	request is executed, so do not change your umask.
524		715
525	aio_rmdir $pathname, $callback->($status)	716	aio_rmdir $pathname, $callback->($status)
526	Asynchronously rmdir (delete) a directory and call the callback with	717	Asynchronously rmdir (delete) a directory and call the callback with
527	the result code.	718	the result code.
528		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
529	aio_readdir $pathname, $callback->($entries)	724	aio_readdir $pathname, $callback->($entries)
530	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
531	entire directory (i.e. opendir + readdir + closedir). The entries	726	entire directory (i.e. opendir + readdir + closedir). The entries
532	will not be sorted, and will NOT include the "." and ".." entries.	727	will not be sorted, and will NOT include the "." and ".." entries.
533		728
534	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
535	an array-ref with the filenames.	730	an array-ref with the filenames.
536		731
537	aio_readdirx $pathname, $flags, $callback->($entries, $flags)	732	aio_readdirx $pathname, $flags, $callback->($entries, $flags)
538	Quite similar to "aio_readdir", but the $flags argument allows to	733	Quite similar to "aio_readdir", but the $flags argument allows one
539	tune behaviour and output format. In case of an error, $entries will	734	to tune behaviour and output format. In case of an error, $entries
540	be "undef".	735	will be "undef".
541		736
542	The flags are a combination of the following constants, ORed	737	The flags are a combination of the following constants, ORed
543	together (the flags will also be passed to the callback, possibly	738	together (the flags will also be passed to the callback, possibly
544	modified):	739	modified):
545		740
546	IO::AIO::READDIR_DENTS	741	IO::AIO::READDIR_DENTS
547	When this flag is off, then the callback gets an arrayref with	742	When this flag is off, then the callback gets an arrayref
548	of names only (as with "aio_readdir"), otherwise it gets an	743	consisting of names only (as with "aio_readdir"), otherwise it
549	arrayref with "[$name, $type, $inode]" arrayrefs, each	744	gets an arrayref with "[$name, $type, $inode]" arrayrefs, each
550	describing a single directory entry in more detail.	745	describing a single directory entry in more detail.
551		746
552	$name is the name of the entry.	747	$name is the name of the entry.
553		748
554	$type is one of the "IO::AIO::DT_xxx" constants:	749	$type is one of the "IO::AIO::DT_xxx" constants:
…		…
567	unspecified content on systems that do not deliver the inode	762	unspecified content on systems that do not deliver the inode
568	information.	763	information.
569		764
570	IO::AIO::READDIR_DIRS_FIRST	765	IO::AIO::READDIR_DIRS_FIRST
571	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
572	order where likely directories come first. This is useful when	767	order where likely directories come first, in optimal stat
573	you need to quickly find directories, or you want to find all	768	order. This is useful when you need to quickly find directories,
574	directories while avoiding to stat() each entry.	769	or you want to find all directories while avoiding to stat()
		770	each entry.
575		771
576	If the system returns type information in readdir, then this is	772	If the system returns type information in readdir, then this is
577	used to find directories directly. Otherwise, likely directories	773	used to find directories directly. Otherwise, likely directories
578	are files beginning with ".", or otherwise files with no dots,	774	are names beginning with ".", or otherwise names with no dots,
579	of which files with short names are tried first.	775	of which names with short names are tried first.
580		776
581	IO::AIO::READDIR_STAT_ORDER	777	IO::AIO::READDIR_STAT_ORDER
582	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
583	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
584	to stat() all files in the given directory, then the returned	780	to stat() all files in the given directory, then the returned
…		…
589	optimal stat order.	785	optimal stat order.
590		786
591	IO::AIO::READDIR_FOUND_UNKNOWN	787	IO::AIO::READDIR_FOUND_UNKNOWN
592	This flag should not be set when calling "aio_readdirx".	788	This flag should not be set when calling "aio_readdirx".
593	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
594	$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
595	flag therefore indicates that all $type's are known, which can	791	flag therefore indicates that all $type's are known, which can
596	be used to speed up some algorithms.	792	be used to speed up some algorithms.
597		793
598	aio_load $path, $data, $callback->($status)	794	aio_load $pathname, $data, $callback->($status)
599	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
600	into memory. Status is the same as with aio_read.	796	into memory. Status is the same as with aio_read.
601		797
602	aio_copy $srcpath, $dstpath, $callback->($status)	798	aio_copy $srcpath, $dstpath, $callback->($status)
603	Try to copy the file (directories not supported as either source	799	Try to copy the file (directories not supported as either source
…		…
620		816
621	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;
622	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"
623	and, if that is successful, unlinks the $srcpath.	819	and, if that is successful, unlinks the $srcpath.
624		820
625	aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	821	aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
626	Scans a directory (similar to "aio_readdir") but additionally tries	822	Scans a directory (similar to "aio_readdir") but additionally tries
627	to efficiently separate the entries of directory $path into two sets	823	to efficiently separate the entries of directory $path into two sets
628	of names, directories you can recurse into (directories), and ones	824	of names, directories you can recurse into (directories), and ones
629	you cannot recurse into (everything else, including symlinks to	825	you cannot recurse into (everything else, including symlinks to
630	directories).	826	directories).
…		…
663	Then entries will be sorted into likely directories a non-initial	859	Then entries will be sorted into likely directories a non-initial
664	dot currently) and likely non-directories (see "aio_readdirx"). Then	860	dot currently) and likely non-directories (see "aio_readdirx"). Then
665	every entry plus an appended "/." will be "stat"'ed, likely	861	every entry plus an appended "/." will be "stat"'ed, likely
666	directories first, in order of their inode numbers. If that	862	directories first, in order of their inode numbers. If that
667	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
668	directory (which will be checked seperately). This is often faster	864	directory (which will be checked separately). This is often faster
669	than stat'ing the entry itself because filesystems might detect the	865	than stat'ing the entry itself because filesystems might detect the
670	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
671	filetype feature), even on systems that cannot return the filetype	867	filetype feature), even on systems that cannot return the filetype
672	information on readdir.	868	information on readdir.
673		869
…		…
679		875
680	It will also likely work on non-POSIX filesystems with reduced	876	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	877	efficiency as those tend to return 0 or 1 as link counts, which
682	disables the directory counting heuristic.	878	disables the directory counting heuristic.
683		879
684	aio_rmtree $path, $callback->($status)	880	aio_rmtree $pathname, $callback->($status)
685	Delete a directory tree starting (and including) $path, return the	881	Delete a directory tree starting (and including) $path, return the
686	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
687	uses "aio_scandir" to recurse into and rmdir directories, and unlink	883	uses "aio_scandir" to recurse into and rmdir directories, and unlink
688	everything else.	884	everything else.
689		885
…		…
698	Asynchronously call fdatasync on the given filehandle and call the	894	Asynchronously call fdatasync on the given filehandle and call the
699	callback with the fdatasync result code.	895	callback with the fdatasync result code.
700		896
701	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
702	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.
703		905
704	aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)	906	aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
705	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
706	to disk (but NOT the metadata), by calling the Linux-specific	908	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	909	sync_file_range call. If sync_file_range is not available or it
…		…
711	"IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE",	913	"IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE",
712	"IO::AIO::SYNC_FILE_RANGE_WRITE" and	914	"IO::AIO::SYNC_FILE_RANGE_WRITE" and
713	"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
714	manpage for details.	916	manpage for details.
715		917
716	aio_pathsync $path, $callback->($status)	918	aio_pathsync $pathname, $callback->($status)
717	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
718	a composite request intended to sync directories after directory	920	a composite request intended to sync directories after directory
719	operations (E.g. rename). This might not work on all operating	921	operations (E.g. rename). This might not work on all operating
720	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
721	directory changes get written to disc. It works for anything that	923	directory changes get written to disc. It works for anything that
…		…
748		950
749	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
750	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
751	"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
752	reads all pages and ensures they are instantiated) or	954	reads all pages and ensures they are instantiated) or
753	"IO::AIO::MT_MODIFY", which modifies the memory page s(by reading	955	"IO::AIO::MT_MODIFY", which modifies the memory pages (by reading
754	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.
755		1045
756	aio_group $callback->(...)	1046	aio_group $callback->(...)
757	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
758	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
759	to bundle many requests into a single, composite, request with a	1049	to bundle many requests into a single, composite, request with a
…		…
793	While it is theoretically handy to have simple I/O scheduling	1083	While it is theoretically handy to have simple I/O scheduling
794	requests like sleep and file handle readable/writable, the overhead	1084	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	1085	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	1086	not use this function except to put your application under
797	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.
798		1209
799	IO::AIO::REQ CLASS	1210	IO::AIO::REQ CLASS
800	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
801	called in non-void context.	1212	called in non-void context.
802		1213
…		…
902	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
903	attached generator that generates requests if idle. The idea behind	1314	attached generator that generates requests if idle. The idea behind
904	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
905	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
906	long time. For example, "aio_scandir" might generate hundreds of	1317	long time. For example, "aio_scandir" might generate hundreds of
907	thousands "aio_stat" requests, delaying any later requests for a	1318	thousands of "aio_stat" requests, delaying any later requests for a
908	long time.	1319	long time.
909		1320
910	To avoid this, and allow incremental generation of requests, you can	1321	To avoid this, and allow incremental generation of requests, you can
911	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
912	requests. The feed callback will be called whenever there are few	1323	requests. The feed callback will be called whenever there are few
…		…
954	results.	1365	results.
955		1366
956	See "poll_cb" for an example.	1367	See "poll_cb" for an example.
957		1368
958	IO::AIO::poll_cb	1369	IO::AIO::poll_cb
959	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
960	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
961	it returned earlier for whatever reason. Returns immediately when no	1372	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		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
966	If not all requests were processed for whatever reason, the	1380	If not all requests were processed for whatever reason, the poll
967	filehandle will still be ready when "poll_cb" returns, so normally	1381	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.	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.
969		1391
970	Example: Install an Event watcher that automatically calls	1392	Example: Install an Event watcher that automatically calls
971	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
972	the SYNOPSIS section, at the top of this document):	1394	the SYNOPSIS section, at the top of this document):
973		1395
974	Event->io (fd => IO::AIO::poll_fileno,	1396	Event->io (fd => IO::AIO::poll_fileno,
975	poll => 'r', async => 1,	1397	poll => 'r', async => 1,
976	cb => \&IO::AIO::poll_cb);	1398	cb => \&IO::AIO::poll_cb);
977		1399
978	IO::AIO::poll_wait	1400	IO::AIO::poll_wait
979	If there are any outstanding requests and none of them in the result	1401	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	1402	requests are outstanding anymore.
981	(simply does a "select" on the filehandle. This is useful if you	1403
982	want to synchronously wait for some requests to finish).	1404	This is useful if you want to synchronously wait for some requests
		1405	to become ready, without actually handling them.
983		1406
984	See "nreqs" for an example.	1407	See "nreqs" for an example.
985		1408
986	IO::AIO::poll	1409	IO::AIO::poll
987	Waits until some requests have been handled.	1410	Waits until some requests have been handled.
…		…
1067		1490
1068	Under normal circumstances you don't need to call this function.	1491	Under normal circumstances you don't need to call this function.
1069		1492
1070	IO::AIO::max_idle $nthreads	1493	IO::AIO::max_idle $nthreads
1071	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
1072	(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
1073	seconds). That means if a thread becomes idle while $nthreads other	1496	timeout (default: 10 seconds). That means if a thread becomes idle
1074	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.
1075		1499
1076	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
1077	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
1078	resources under normal circumstances (1000 threads can easily	1502	resources under normal circumstances (1000 threads can easily
1079	consume 30MB of RAM).	1503	consume 30MB of RAM).
1080		1504
1081	The default is probably ok in most situations, especially if thread	1505	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	1506	creation is fast. If thread creation is very slow on your system you
1083	might want to use larger values.	1507	might want to use larger values.
1084		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
1085	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
1086	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
1087	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
1088	inexact: Better use an "aio_group" together with a feed callback.	1525	inexact: Better use an "aio_group" together with a feed callback.
1089		1526
1090	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
1091	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:
1092	"poll_cb" (and "poll_some" and other functions calling "poll_cb")
1093	function will block until the limit is no longer exceeded.
1094		1529
1095	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
1096	the number of outstanding requests.	1546	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		1547
1103	STATISTICAL INFORMATION	1548	STATISTICAL INFORMATION
1104	IO::AIO::nreqs	1549	IO::AIO::nreqs
1105	Returns the number of requests currently in the ready, execute or	1550	Returns the number of requests currently in the ready, execute or
1106	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
…		…
1130	set to non-blocking operations).	1575	set to non-blocking operations).
1131		1576
1132	Returns the number of bytes copied, or -1 on error.	1577	Returns the number of bytes copied, or -1 on error.
1133		1578
1134	IO::AIO::fadvise $fh, $offset, $len, $advice	1579	IO::AIO::fadvise $fh, $offset, $len, $advice
1135	Simply calls the "posix_fadvise" function (see it's manpage for	1580	Simply calls the "posix_fadvise" function (see its manpage for
1136	details). The following advice constants are avaiable:	1581	details). The following advice constants are available:
1137	"IO::AIO::FADV_NORMAL", "IO::AIO::FADV_SEQUENTIAL",	1582	"IO::AIO::FADV_NORMAL", "IO::AIO::FADV_SEQUENTIAL",
1138	"IO::AIO::FADV_RANDOM", "IO::AIO::FADV_NOREUSE",	1583	"IO::AIO::FADV_RANDOM", "IO::AIO::FADV_NOREUSE",
1139	"IO::AIO::FADV_WILLNEED", "IO::AIO::FADV_DONTNEED".	1584	"IO::AIO::FADV_WILLNEED", "IO::AIO::FADV_DONTNEED".
1140		1585
1141	On systems that do not implement "posix_fadvise", this function	1586	On systems that do not implement "posix_fadvise", this function
1142	returns ENOSYS, otherwise the return value of "posix_fadvise".	1587	returns ENOSYS, otherwise the return value of "posix_fadvise".
1143		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
1144	IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]	1608	IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
1145	Memory-maps a file (or anonymous memory range) and attaches it to	1609	Memory-maps a file (or anonymous memory range) and attaches it to
1146	the given $scalar, which will act like a string scalar.	1610	the given $scalar, which will act like a string scalar. Returns true
		1611	on success, and false otherwise.
1147		1612
1148	The only operations allowed on the scalar are "substr"/"vec" that	1613	The only operations allowed on the scalar are "substr"/"vec" that
1149	don't change the string length, and most read-only operations such	1614	don't change the string length, and most read-only operations such
1150	as copying it or searching it with regexes and so on.	1615	as copying it or searching it with regexes and so on.
1151		1616
…		…
1192	my $fast_md5 = md5 $data;	1657	my $fast_md5 = md5 $data;
1193		1658
1194	IO::AIO::munmap $scalar	1659	IO::AIO::munmap $scalar
1195	Removes a previous mmap and undefines the $scalar.	1660	Removes a previous mmap and undefines the $scalar.
1196		1661
1197	IO::AIO::mlockall $flags	1662	IO::AIO::munlock $scalar, $offset = 0, $length = undef
1198	Calls the "mlockall" function with the given $flags (a combination	1663	Calls the "munlock" function, undoing the effects of a previous
1199	of "IO::AIO::MCL_CURRENT" and "IO::AIO::MCL__FUTURE").	1664	"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		1665
1204	IO::AIO::munlockall	1666	IO::AIO::munlockall
1205	Calls the "munlockall" function.	1667	Calls the "munlockall" function.
1206		1668
1207	On systems that do not implement "munlockall", this function returns	1669	On systems that do not implement "munlockall", this function returns
1208	ENOSYS, otherwise the return value of "munlockall".	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.
1209		1689
1210	EVENT LOOP INTEGRATION	1690	EVENT LOOP INTEGRATION
1211	It is recommended to use AnyEvent::AIO to integrate IO::AIO	1691	It is recommended to use AnyEvent::AIO to integrate IO::AIO
1212	automatically into many event loops:	1692	automatically into many event loops:
1213		1693
…		…
1236	# Danga::Socket integration	1716	# Danga::Socket integration
1237	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>	1717	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
1238	\&IO::AIO::poll_cb);	1718	\&IO::AIO::poll_cb);
1239		1719
1240	FORK BEHAVIOUR	1720	FORK BEHAVIOUR
1241	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.
1242		1728
1243	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
1244	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
1245	fork the parent simply leaves the quiescent state and continues	1731	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		1732
1251	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.
1252	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:
1253	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.
1254		1747
1255	MEMORY USAGE	1748	MEMORY USAGE
1256	Per-request usage:	1749	Per-request usage:
1257		1750
1258	Each aio request uses - depending on your architecture - around 100-200	1751	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 1.54 by root, Sun Jan 6 11:48:14 2013 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 1.54 by root, Sun Jan 6 11:48:14 2013 UTC