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

Comparing IO-AIO/README (file contents):
Revision 1.27 by root, Sat Oct 6 14:05:37 2007 UTC vs.
Revision 1.52 by root, Tue Apr 10 05:01:33 2012 UTC

…		…
2	IO::AIO - Asynchronous Input/Output	2	IO::AIO - Asynchronous Input/Output
3		3
4	SYNOPSIS	4	SYNOPSIS
5	use IO::AIO;	5	use IO::AIO;
6		6
7	aio_open "/etc/passwd", O_RDONLY, 0, sub {	7	aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
8	my $fh = shift	8	my $fh = shift
9	or die "/etc/passwd: $!";	9	or die "/etc/passwd: $!";
10	...	10	...
11	};	11	};
12		12
…		…
24	$req->cancel; # cancel request if still in queue	24	$req->cancel; # cancel request if still in queue
25		25
26	my $grp = aio_group sub { print "all stats done\n" };	26	my $grp = aio_group sub { print "all stats done\n" };
27	add $grp aio_stat "..." for ...;	27	add $grp aio_stat "..." for ...;
28		28
29	# AnyEvent integration
30	open my $fh, "<&=" . IO::AIO::poll_fileno or die "$!";
31	my $w = AnyEvent->io (fh => $fh, poll => 'r', cb => sub { IO::AIO::poll_cb });
32
33	# Event integration
34	Event->io (fd => IO::AIO::poll_fileno,
35	poll => 'r',
36	cb => \&IO::AIO::poll_cb);
37
38	# Glib/Gtk2 integration
39	add_watch Glib::IO IO::AIO::poll_fileno,
40	in => sub { IO::AIO::poll_cb; 1 };
41
42	# Tk integration
43	Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
44	readable => \&IO::AIO::poll_cb);
45
46	# Danga::Socket integration
47	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
48	\&IO::AIO::poll_cb);
49
50	DESCRIPTION	29	DESCRIPTION
51	This module implements asynchronous I/O using whatever means your	30	This module implements asynchronous I/O using whatever means your
52	operating system supports.	31	operating system supports. It is implemented as an interface to "libeio"
		32	(<http://software.schmorp.de/pkg/libeio.html>).
53		33
54	Asynchronous means that operations that can normally block your program	34	Asynchronous means that operations that can normally block your program
55	(e.g. reading from disk) will be done asynchronously: the operation will	35	(e.g. reading from disk) will be done asynchronously: the operation will
56	still block, but you can do something else in the meantime. This is	36	still block, but you can do something else in the meantime. This is
57	extremely useful for programs that need to stay interactive even when	37	extremely useful for programs that need to stay interactive even when
…		…
62	operations concurrently.	42	operations concurrently.
63		43
64	While most of this works on all types of file descriptors (for example	44	While most of this works on all types of file descriptors (for example
65	sockets), using these functions on file descriptors that support	45	sockets), using these functions on file descriptors that support
66	nonblocking operation (again, sockets, pipes etc.) is very inefficient.	46	nonblocking operation (again, sockets, pipes etc.) is very inefficient.
67	Use an event loop for that (such as the Event module): IO::AIO will	47	Use an event loop for that (such as the EV module): IO::AIO will
68	naturally fit into such an event loop itself.	48	naturally fit into such an event loop itself.
69		49
70	In this version, a number of threads are started that execute your	50	In this version, a number of threads are started that execute your
71	requests and signal their completion. You don't need thread support in	51	requests and signal their completion. You don't need thread support in
72	perl, and the threads created by this module will not be visible to	52	perl, and the threads created by this module will not be visible to
…		…
81	it is currently not reentrant in any way, so use appropriate locking	61	it is currently not reentrant in any way, so use appropriate locking
82	yourself, always call "poll_cb" from within the same thread, or never	62	yourself, always call "poll_cb" from within the same thread, or never
83	call "poll_cb" (or other "aio_" functions) recursively.	63	call "poll_cb" (or other "aio_" functions) recursively.
84		64
85	EXAMPLE	65	EXAMPLE
86	This is a simple example that uses the Event module and loads	66	This is a simple example that uses the EV module and loads /etc/passwd
87	/etc/passwd asynchronously:	67	asynchronously:
88		68
89	use Fcntl;	69	use Fcntl;
90	use Event;	70	use EV;
91	use IO::AIO;	71	use IO::AIO;
92		72
93	# register the IO::AIO callback with Event	73	# register the IO::AIO callback with EV
94	Event->io (fd => IO::AIO::poll_fileno,	74	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
95	poll => 'r',
96	cb => \&IO::AIO::poll_cb);
97		75
98	# queue the request to open /etc/passwd	76	# queue the request to open /etc/passwd
99	aio_open "/etc/passwd", O_RDONLY, 0, sub {	77	aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
100	my $fh = shift	78	my $fh = shift
101	or die "error while opening: $!";	79	or die "error while opening: $!";
102		80
103	# stat'ing filehandles is generally non-blocking	81	# stat'ing filehandles is generally non-blocking
104	my $size = -s $fh;	82	my $size = -s $fh;
…		…
113		91
114	# file contents now in $contents	92	# file contents now in $contents
115	print $contents;	93	print $contents;
116		94
117	# exit event loop and program	95	# exit event loop and program
118	Event::unloop;	96	EV::unloop;
119	};	97	};
120	};	98	};
121		99
122	# possibly queue up other requests, or open GUI windows,	100	# possibly queue up other requests, or open GUI windows,
123	# check for sockets etc. etc.	101	# check for sockets etc. etc.
124		102
125	# process events as long as there are some:	103	# process events as long as there are some:
126	Event::loop;	104	EV::loop;
127		105
128	REQUEST ANATOMY AND LIFETIME	106	REQUEST ANATOMY AND LIFETIME
129	Every "aio_*" function creates a request. which is a C data structure	107	Every "aio_*" function creates a request. which is a C data structure
130	not directly visible to Perl.	108	not directly visible to Perl.
131		109
…		…
167	anymore (except possibly for the Perl object, but its connection to	145	anymore (except possibly for the Perl object, but its connection to
168	the actual aio request is severed and calling its methods will	146	the actual aio request is severed and calling its methods will
169	either do nothing or result in a runtime error).	147	either do nothing or result in a runtime error).
170		148
171	FUNCTIONS	149	FUNCTIONS
172	AIO REQUEST FUNCTIONS	150	QUICK OVERVIEW
		151	This section simply lists the prototypes of the most important functions
		152	for quick reference. See the following sections for function-by-function
		153	documentation.
		154
		155	aio_wd $pathname, $callback->($wd)
		156	aio_open $pathname, $flags, $mode, $callback->($fh)
		157	aio_close $fh, $callback->($status)
		158	aio_seek $fh,$offset,$whence, $callback->($offs)
		159	aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
		160	aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
		161	aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
		162	aio_readahead $fh,$offset,$length, $callback->($retval)
		163	aio_stat $fh_or_path, $callback->($status)
		164	aio_lstat $fh, $callback->($status)
		165	aio_statvfs $fh_or_path, $callback->($statvfs)
		166	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
		167	aio_chown $fh_or_path, $uid, $gid, $callback->($status)
		168	aio_chmod $fh_or_path, $mode, $callback->($status)
		169	aio_truncate $fh_or_path, $offset, $callback->($status)
		170	aio_unlink $pathname, $callback->($status)
		171	aio_mknod $pathname, $mode, $dev, $callback->($status)
		172	aio_link $srcpath, $dstpath, $callback->($status)
		173	aio_symlink $srcpath, $dstpath, $callback->($status)
		174	aio_readlink $pathname, $callback->($link)
		175	aio_realpath $pathname, $callback->($link)
		176	aio_rename $srcpath, $dstpath, $callback->($status)
		177	aio_mkdir $pathname, $mode, $callback->($status)
		178	aio_rmdir $pathname, $callback->($status)
		179	aio_readdir $pathname, $callback->($entries)
		180	aio_readdirx $pathname, $flags, $callback->($entries, $flags)
		181	IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST
		182	IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN
		183	aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
		184	aio_load $pathname, $data, $callback->($status)
		185	aio_copy $srcpath, $dstpath, $callback->($status)
		186	aio_move $srcpath, $dstpath, $callback->($status)
		187	aio_rmtree $pathname, $callback->($status)
		188	aio_sync $callback->($status)
		189	aio_syncfs $fh, $callback->($status)
		190	aio_fsync $fh, $callback->($status)
		191	aio_fdatasync $fh, $callback->($status)
		192	aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
		193	aio_pathsync $pathname, $callback->($status)
		194	aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		195	aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		196	aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
		197	aio_mlockall $flags, $callback->($status)
		198	aio_group $callback->(...)
		199	aio_nop $callback->()
		200
		201	$prev_pri = aioreq_pri [$pri]
		202	aioreq_nice $pri_adjust
		203
		204	IO::AIO::poll_wait
		205	IO::AIO::poll_cb
		206	IO::AIO::poll
		207	IO::AIO::flush
		208	IO::AIO::max_poll_reqs $nreqs
		209	IO::AIO::max_poll_time $seconds
		210	IO::AIO::min_parallel $nthreads
		211	IO::AIO::max_parallel $nthreads
		212	IO::AIO::max_idle $nthreads
		213	IO::AIO::idle_timeout $seconds
		214	IO::AIO::max_outstanding $maxreqs
		215	IO::AIO::nreqs
		216	IO::AIO::nready
		217	IO::AIO::npending
		218
		219	IO::AIO::sendfile $ofh, $ifh, $offset, $count
		220	IO::AIO::fadvise $fh, $offset, $len, $advice
		221	IO::AIO::madvise $scalar, $offset, $length, $advice
		222	IO::AIO::mprotect $scalar, $offset, $length, $protect
		223	IO::AIO::munlock $scalar, $offset = 0, $length = undef
		224	IO::AIO::munlockall
		225
		226	API NOTES
173	All the "aio_*" calls are more or less thin wrappers around the syscall	227	All the "aio_*" calls are more or less thin wrappers around the syscall
174	with the same name (sans "aio_"). The arguments are similar or	228	with the same name (sans "aio_"). The arguments are similar or
175	identical, and they all accept an additional (and optional) $callback	229	identical, and they all accept an additional (and optional) $callback
176	argument which must be a code reference. This code reference will get	230	argument which must be a code reference. This code reference will be
177	called with the syscall return code (e.g. most syscalls return -1 on	231	called after the syscall has been executed in an asynchronous fashion.
178	error, unlike perl, which usually delivers "false") as it's sole	232	The results of the request will be passed as arguments to the callback
179	argument when the given syscall has been executed asynchronously.	233	(and, if an error occured, in $!) - for most requests the syscall return
		234	code (e.g. most syscalls return -1 on error, unlike perl, which usually
		235	delivers "false").
		236
		237	Some requests (such as "aio_readdir") pass the actual results and
		238	communicate failures by passing "undef".
180		239
181	All functions expecting a filehandle keep a copy of the filehandle	240	All functions expecting a filehandle keep a copy of the filehandle
182	internally until the request has finished.	241	internally until the request has finished.
183		242
184	All functions return request objects of type IO::AIO::REQ that allow	243	All functions return request objects of type IO::AIO::REQ that allow
185	further manipulation of those requests while they are in-flight.	244	further manipulation of those requests while they are in-flight.
186		245
187	The pathnames you pass to these routines must be absolute and encoded	246	The pathnames you pass to these routines should be absolute. The
188	as octets. The reason for the former is that at the time the request is	247	reason for this is that at the time the request is being executed, the
189	being executed, the current working directory could have changed.	248	current working directory could have changed. Alternatively, you can
190	Alternatively, you can make sure that you never change the current	249	make sure that you never change the current working directory anywhere
191	working directory anywhere in the program and then use relative paths.	250	in the program and then use relative paths. You can also take advantage
		251	of IO::AIOs working directory abstraction, that lets you specify paths
		252	relative to some previously-opened "working directory object" - see the
		253	description of the "IO::AIO::WD" class later in this document.
192		254
193	To encode pathnames as octets, either make sure you either: a) always	255	To encode pathnames as octets, either make sure you either: a) always
194	pass in filenames you got from outside (command line, readdir etc.)	256	pass in filenames you got from outside (command line, readdir etc.)
195	without tinkering, b) are ASCII or ISO 8859-1, c) use the Encode module	257	without tinkering, b) are in your native filesystem encoding, c) use the
196	and encode your pathnames to the locale (or other) encoding in effect in	258	Encode module and encode your pathnames to the locale (or other)
197	the user environment, d) use Glib::filename_from_unicode on unicode	259	encoding in effect in the user environment, d) use
198	filenames or e) use something else to ensure your scalar has the correct	260	Glib::filename_from_unicode on unicode filenames or e) use something
199	contents.	261	else to ensure your scalar has the correct contents.
200		262
201	This works, btw. independent of the internal UTF-8 bit, which IO::AIO	263	This works, btw. independent of the internal UTF-8 bit, which IO::AIO
202	handles correctly wether it is set or not.	264	handles correctly whether it is set or not.
203		265
		266	AIO REQUEST FUNCTIONS
204	$prev_pri = aioreq_pri [$pri]	267	$prev_pri = aioreq_pri [$pri]
205	Returns the priority value that would be used for the next request	268	Returns the priority value that would be used for the next request
206	and, if $pri is given, sets the priority for the next aio request.	269	and, if $pri is given, sets the priority for the next aio request.
207		270
208	The default priority is 0, the minimum and maximum priorities are -4	271	The default priority is 0, the minimum and maximum priorities are -4
…		…
247	will be modified by the umask in effect then the request is being	310	will be modified by the umask in effect then the request is being
248	executed, so better never change the umask.	311	executed, so better never change the umask.
249		312
250	Example:	313	Example:
251		314
252	aio_open "/etc/passwd", O_RDONLY, 0, sub {	315	aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
253	if ($_[0]) {	316	if ($_[0]) {
254	print "open successful, fh is $_[0]\n";	317	print "open successful, fh is $_[0]\n";
255	...	318	...
256	} else {	319	} else {
257	die "open failed: $!\n";	320	die "open failed: $!\n";
258	}	321	}
259	};	322	};
260		323
		324	In addition to all the common open modes/flags ("O_RDONLY",
		325	"O_WRONLY", "O_RDWR", "O_CREAT", "O_TRUNC", "O_EXCL" and
		326	"O_APPEND"), the following POSIX and non-POSIX constants are
		327	available (missing ones on your system are, as usual, 0):
		328
		329	"O_ASYNC", "O_DIRECT", "O_NOATIME", "O_CLOEXEC", "O_NOCTTY",
		330	"O_NOFOLLOW", "O_NONBLOCK", "O_EXEC", "O_SEARCH", "O_DIRECTORY",
		331	"O_DSYNC", "O_RSYNC", "O_SYNC" and "O_TTY_INIT".
		332
261	aio_close $fh, $callback->($status)	333	aio_close $fh, $callback->($status)
262	Asynchronously close a file and call the callback with the result	334	Asynchronously close a file and call the callback with the result
263	code.	335	code.
264		336
265	Unfortunately, you can't do this to perl. Perl insists very	337	Unfortunately, you can't do this to perl. Perl insists very
266	strongly on closing the file descriptor associated with the	338	strongly on closing the file descriptor associated with the
267	filehandle itself. Here is what aio_close will try:	339	filehandle itself.
268		340
269	1. dup()licate the fd	341	Therefore, "aio_close" will not close the filehandle - instead it
270	2. asynchronously close() the duplicated fd	342	will use dup2 to overwrite the file descriptor with the write-end of
271	3. dup()licate the fd once more	343	a pipe (the pipe fd will be created on demand and will be cached).
272	4. let perl close() the filehandle
273	5. asynchronously close the duplicated fd
274		344
275	The idea is that the first close() flushes stuff to disk that	345	Or in other words: the file descriptor will be closed, but it will
276	closing an fd will flush, so when perl closes the fd, nothing much	346	not be free for reuse until the perl filehandle is closed.
277	will need to be flushed. The second async. close() will then flush
278	stuff to disk that closing the last fd to the file will flush.
279		347
280	Just FYI, SuSv3 has this to say on close:	348	aio_seek $fh, $offset, $whence, $callback->($offs)
		349	Seeks the filehandle to the new $offset, similarly to perl's
		350	"sysseek". The $whence can use the traditional values (0 for
		351	"IO::AIO::SEEK_SET", 1 for "IO::AIO::SEEK_CUR" or 2 for
		352	"IO::AIO::SEEK_END").
281		353
282	All outstanding record locks owned by the process on the file	354	The resulting absolute offset will be passed to the callback, or -1
283	associated with the file descriptor shall be removed.	355	in case of an error.
284		356
285	If fildes refers to a socket, close() shall cause the socket to be	357	In theory, the $whence constants could be different than the
286	destroyed. ... close() shall block for up to the current linger	358	corresponding values from Fcntl, but perl guarantees they are the
287	interval until all data is transmitted.	359	same, so don't panic.
288	[this actually sounds like a specification bug, but who knows]
289		360
290	And at least Linux additionally actually flushes stuff on every	361	As a GNU/Linux (and maybe Solaris) extension, also the constants
291	close, even when the file itself is still open.	362	"IO::AIO::SEEK_DATA" and "IO::AIO::SEEK_HOLE" are available, if they
292		363	could be found. No guarantees about suitability for use in
293	Sounds enourmously inefficient and complicated? Yes... please show	364	"aio_seek" or Perl's "sysseek" can be made though, although I would
294	me how to nuke perl's fd out of existence...	365	naively assume they "just work".
295		366
296	aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	367	aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
297	aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	368	aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
298	Reads or writes $length bytes from the specified $fh and $offset	369	Reads or writes $length bytes from or to the specified $fh and
299	into the scalar given by $data and offset $dataoffset and calls the	370	$offset into the scalar given by $data and offset $dataoffset and
300	callback without the actual number of bytes read (or -1 on error,	371	calls the callback without the actual number of bytes read (or -1 on
301	just like the syscall).	372	error, just like the syscall).
		373
		374	"aio_read" will, like "sysread", shrink or grow the $data scalar to
		375	offset plus the actual number of bytes read.
302		376
303	If $offset is undefined, then the current file descriptor offset	377	If $offset is undefined, then the current file descriptor offset
304	will be used (and updated), otherwise the file descriptor offset	378	will be used (and updated), otherwise the file descriptor offset
305	will not be changed by these calls.	379	will not be changed by these calls.
306		380
…		…
325	aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)	399	aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
326	Tries to copy $length bytes from $in_fh to $out_fh. It starts	400	Tries to copy $length bytes from $in_fh to $out_fh. It starts
327	reading at byte offset $in_offset, and starts writing at the current	401	reading at byte offset $in_offset, and starts writing at the current
328	file offset of $out_fh. Because of that, it is not safe to issue	402	file offset of $out_fh. Because of that, it is not safe to issue
329	more than one "aio_sendfile" per $out_fh, as they will interfere	403	more than one "aio_sendfile" per $out_fh, as they will interfere
330	with each other.	404	with each other. The same $in_fh works fine though, as this function
		405	does not move or use the file offset of $in_fh.
331		406
		407	Please note that "aio_sendfile" can read more bytes from $in_fh than
		408	are written, and there is no way to find out how many more bytes
		409	have been read from "aio_sendfile" alone, as "aio_sendfile" only
		410	provides the number of bytes written to $out_fh. Only if the result
		411	value equals $length one can assume that $length bytes have been
		412	read.
		413
		414	Unlike with other "aio_" functions, it makes a lot of sense to use
		415	"aio_sendfile" on non-blocking sockets, as long as one end
		416	(typically the $in_fh) is a file - the file I/O will then be
		417	asynchronous, while the socket I/O will be non-blocking. Note,
		418	however, that you can run into a trap where "aio_sendfile" reads
		419	some data with readahead, then fails to write all data, and when the
		420	socket is ready the next time, the data in the cache is already
		421	lost, forcing "aio_sendfile" to again hit the disk. Explicit
		422	"aio_read" + "aio_write" let's you better control resource usage.
		423
332	This call tries to make use of a native "sendfile" syscall to	424	This call tries to make use of a native "sendfile"-like syscall to
333	provide zero-copy operation. For this to work, $out_fh should refer	425	provide zero-copy operation. For this to work, $out_fh should refer
334	to a socket, and $in_fh should refer to mmap'able file.	426	to a socket, and $in_fh should refer to an mmap'able file.
335		427
336	If the native sendfile call fails or is not implemented, it will be	428	If a native sendfile cannot be found or it fails with "ENOSYS",
337	emulated, so you can call "aio_sendfile" on any type of filehandle	429	"EINVAL", "ENOTSUP", "EOPNOTSUPP", "EAFNOSUPPORT", "EPROTOTYPE" or
338	regardless of the limitations of the operating system.	430	"ENOTSOCK", it will be emulated, so you can call "aio_sendfile" on
		431	any type of filehandle regardless of the limitations of the
		432	operating system.
339		433
340	Please note, however, that "aio_sendfile" can read more bytes from	434	As native sendfile syscalls (as practically any non-POSIX interface
341	$in_fh than are written, and there is no way to find out how many	435	hacked together in a hurry to improve benchmark numbers) tend to be
342	bytes have been read from "aio_sendfile" alone, as "aio_sendfile"	436	rather buggy on many systems, this implementation tries to work
343	only provides the number of bytes written to $out_fh. Only if the	437	around some known bugs in Linux and FreeBSD kernels (probably
344	result value equals $length one can assume that $length bytes have	438	others, too), but that might fail, so you really really should check
345	been read.	439	the return value of "aio_sendfile" - fewre bytes than expected might
		440	have been transferred.
346		441
347	aio_readahead $fh,$offset,$length, $callback->($retval)	442	aio_readahead $fh,$offset,$length, $callback->($retval)
348	"aio_readahead" populates the page cache with data from a file so	443	"aio_readahead" populates the page cache with data from a file so
349	that subsequent reads from that file will not block on disk I/O. The	444	that subsequent reads from that file will not block on disk I/O. The
350	$offset argument specifies the starting point from which data is to	445	$offset argument specifies the starting point from which data is to
…		…
371	Currently, the stats are always 64-bit-stats, i.e. instead of	466	Currently, the stats are always 64-bit-stats, i.e. instead of
372	returning an error when stat'ing a large file, the results will be	467	returning an error when stat'ing a large file, the results will be
373	silently truncated unless perl itself is compiled with large file	468	silently truncated unless perl itself is compiled with large file
374	support.	469	support.
375		470
		471	To help interpret the mode and dev/rdev stat values, IO::AIO offers
		472	the following constants and functions (if not implemented, the
		473	constants will be 0 and the functions will either "croak" or fall
		474	back on traditional behaviour).
		475
		476	"S_IFMT", "S_IFIFO", "S_IFCHR", "S_IFBLK", "S_IFLNK", "S_IFREG",
		477	"S_IFDIR", "S_IFWHT", "S_IFSOCK", "IO::AIO::major $dev_t",
		478	"IO::AIO::minor $dev_t", "IO::AIO::makedev $major, $minor".
		479
376	Example: Print the length of /etc/passwd:	480	Example: Print the length of /etc/passwd:
377		481
378	aio_stat "/etc/passwd", sub {	482	aio_stat "/etc/passwd", sub {
379	$_[0] and die "stat failed: $!";	483	$_[0] and die "stat failed: $!";
380	print "size is ", -s _, "\n";	484	print "size is ", -s _, "\n";
381	};	485	};
382		486
		487	aio_statvfs $fh_or_path, $callback->($statvfs)
		488	Works like the POSIX "statvfs" or "fstatvfs" syscalls, depending on
		489	whether a file handle or path was passed.
		490
		491	On success, the callback is passed a hash reference with the
		492	following members: "bsize", "frsize", "blocks", "bfree", "bavail",
		493	"files", "ffree", "favail", "fsid", "flag" and "namemax". On
		494	failure, "undef" is passed.
		495
		496	The following POSIX IO::AIO::ST_* constants are defined: "ST_RDONLY"
		497	and "ST_NOSUID".
		498
		499	The following non-POSIX IO::AIO::ST_* flag masks are defined to
		500	their correct value when available, or to 0 on systems that do not
		501	support them: "ST_NODEV", "ST_NOEXEC", "ST_SYNCHRONOUS",
		502	"ST_MANDLOCK", "ST_WRITE", "ST_APPEND", "ST_IMMUTABLE",
		503	"ST_NOATIME", "ST_NODIRATIME" and "ST_RELATIME".
		504
		505	Example: stat "/wd" and dump out the data if successful.
		506
		507	aio_statvfs "/wd", sub {
		508	my $f = $_[0]
		509	or die "statvfs: $!";
		510
		511	use Data::Dumper;
		512	say Dumper $f;
		513	};
		514
		515	# result:
		516	{
		517	bsize => 1024,
		518	bfree => 4333064312,
		519	blocks => 10253828096,
		520	files => 2050765568,
		521	flag => 4096,
		522	favail => 2042092649,
		523	bavail => 4333064312,
		524	ffree => 2042092649,
		525	namemax => 255,
		526	frsize => 1024,
		527	fsid => 1810
		528	}
		529
383	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)	530	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
384	Works like perl's "utime" function (including the special case of	531	Works like perl's "utime" function (including the special case of
385	$atime and $mtime being undef). Fractional times are supported if	532	$atime and $mtime being undef). Fractional times are supported if
386	the underlying syscalls support them.	533	the underlying syscalls support them.
387		534
…		…
416		563
417	aio_unlink $pathname, $callback->($status)	564	aio_unlink $pathname, $callback->($status)
418	Asynchronously unlink (delete) a file and call the callback with the	565	Asynchronously unlink (delete) a file and call the callback with the
419	result code.	566	result code.
420		567
421	aio_mknod $path, $mode, $dev, $callback->($status)	568	aio_mknod $pathname, $mode, $dev, $callback->($status)
422	[EXPERIMENTAL]	569	[EXPERIMENTAL]
423		570
424	Asynchronously create a device node (or fifo). See mknod(2).	571	Asynchronously create a device node (or fifo). See mknod(2).
425		572
426	The only (POSIX-) portable way of calling this function is:	573	The only (POSIX-) portable way of calling this function is:
427		574
428	aio_mknod $path, IO::AIO::S_IFIFO \| $mode, 0, sub { ...	575	aio_mknod $pathname, IO::AIO::S_IFIFO \| $mode, 0, sub { ...
		576
		577	See "aio_stat" for info about some potentially helpful extra
		578	constants and functions.
429		579
430	aio_link $srcpath, $dstpath, $callback->($status)	580	aio_link $srcpath, $dstpath, $callback->($status)
431	Asynchronously create a new link to the existing object at $srcpath	581	Asynchronously create a new link to the existing object at $srcpath
432	at the path $dstpath and call the callback with the result code.	582	at the path $dstpath and call the callback with the result code.
433		583
434	aio_symlink $srcpath, $dstpath, $callback->($status)	584	aio_symlink $srcpath, $dstpath, $callback->($status)
435	Asynchronously create a new symbolic link to the existing object at	585	Asynchronously create a new symbolic link to the existing object at
436	$srcpath at the path $dstpath and call the callback with the result	586	$srcpath at the path $dstpath and call the callback with the result
437	code.	587	code.
438		588
439	aio_readlink $path, $callback->($link)	589	aio_readlink $pathname, $callback->($link)
440	Asynchronously read the symlink specified by $path and pass it to	590	Asynchronously read the symlink specified by $path and pass it to
441	the callback. If an error occurs, nothing or undef gets passed to	591	the callback. If an error occurs, nothing or undef gets passed to
442	the callback.	592	the callback.
		593
		594	aio_realpath $pathname, $callback->($path)
		595	Asynchronously make the path absolute and resolve any symlinks in
		596	$path. The resulting path only consists of directories (Same as
		597	Cwd::realpath).
		598
		599	This request can be used to get the absolute path of the current
		600	working directory by passing it a path of . (a single dot).
443		601
444	aio_rename $srcpath, $dstpath, $callback->($status)	602	aio_rename $srcpath, $dstpath, $callback->($status)
445	Asynchronously rename the object at $srcpath to $dstpath, just as	603	Asynchronously rename the object at $srcpath to $dstpath, just as
446	rename(2) and call the callback with the result code.	604	rename(2) and call the callback with the result code.
447		605
…		…
457	aio_readdir $pathname, $callback->($entries)	615	aio_readdir $pathname, $callback->($entries)
458	Unlike the POSIX call of the same name, "aio_readdir" reads an	616	Unlike the POSIX call of the same name, "aio_readdir" reads an
459	entire directory (i.e. opendir + readdir + closedir). The entries	617	entire directory (i.e. opendir + readdir + closedir). The entries
460	will not be sorted, and will NOT include the "." and ".." entries.	618	will not be sorted, and will NOT include the "." and ".." entries.
461		619
462	The callback a single argument which is either "undef" or an	620	The callback is passed a single argument which is either "undef" or
463	array-ref with the filenames.	621	an array-ref with the filenames.
464		622
		623	aio_readdirx $pathname, $flags, $callback->($entries, $flags)
		624	Quite similar to "aio_readdir", but the $flags argument allows one
		625	to tune behaviour and output format. In case of an error, $entries
		626	will be "undef".
		627
		628	The flags are a combination of the following constants, ORed
		629	together (the flags will also be passed to the callback, possibly
		630	modified):
		631
		632	IO::AIO::READDIR_DENTS
		633	When this flag is off, then the callback gets an arrayref
		634	consisting of names only (as with "aio_readdir"), otherwise it
		635	gets an arrayref with "[$name, $type, $inode]" arrayrefs, each
		636	describing a single directory entry in more detail.
		637
		638	$name is the name of the entry.
		639
		640	$type is one of the "IO::AIO::DT_xxx" constants:
		641
		642	"IO::AIO::DT_UNKNOWN", "IO::AIO::DT_FIFO", "IO::AIO::DT_CHR",
		643	"IO::AIO::DT_DIR", "IO::AIO::DT_BLK", "IO::AIO::DT_REG",
		644	"IO::AIO::DT_LNK", "IO::AIO::DT_SOCK", "IO::AIO::DT_WHT".
		645
		646	"IO::AIO::DT_UNKNOWN" means just that: readdir does not know. If
		647	you need to know, you have to run stat yourself. Also, for speed
		648	reasons, the $type scalars are read-only: you can not modify
		649	them.
		650
		651	$inode is the inode number (which might not be exact on systems
		652	with 64 bit inode numbers and 32 bit perls). This field has
		653	unspecified content on systems that do not deliver the inode
		654	information.
		655
		656	IO::AIO::READDIR_DIRS_FIRST
		657	When this flag is set, then the names will be returned in an
		658	order where likely directories come first, in optimal stat
		659	order. This is useful when you need to quickly find directories,
		660	or you want to find all directories while avoiding to stat()
		661	each entry.
		662
		663	If the system returns type information in readdir, then this is
		664	used to find directories directly. Otherwise, likely directories
		665	are names beginning with ".", or otherwise names with no dots,
		666	of which names with short names are tried first.
		667
		668	IO::AIO::READDIR_STAT_ORDER
		669	When this flag is set, then the names will be returned in an
		670	order suitable for stat()'ing each one. That is, when you plan
		671	to stat() all files in the given directory, then the returned
		672	order will likely be fastest.
		673
		674	If both this flag and "IO::AIO::READDIR_DIRS_FIRST" are
		675	specified, then the likely dirs come first, resulting in a less
		676	optimal stat order.
		677
		678	IO::AIO::READDIR_FOUND_UNKNOWN
		679	This flag should not be set when calling "aio_readdirx".
		680	Instead, it is being set by "aio_readdirx", when any of the
		681	$type's found were "IO::AIO::DT_UNKNOWN". The absence of this
		682	flag therefore indicates that all $type's are known, which can
		683	be used to speed up some algorithms.
		684
465	aio_load $path, $data, $callback->($status)	685	aio_load $pathname, $data, $callback->($status)
466	This is a composite request that tries to fully load the given file	686	This is a composite request that tries to fully load the given file
467	into memory. Status is the same as with aio_read.	687	into memory. Status is the same as with aio_read.
468		688
469	aio_copy $srcpath, $dstpath, $callback->($status)	689	aio_copy $srcpath, $dstpath, $callback->($status)
470	Try to copy the file (directories not supported as either source	690	Try to copy the file (directories not supported as either source
471	or destination) from $srcpath to $dstpath and call the callback with	691	or destination) from $srcpath to $dstpath and call the callback with
472	the 0 (error) or -1 ok.	692	a status of 0 (ok) or -1 (error, see $!).
473		693
474	This is a composite request that it creates the destination file	694	This is a composite request that creates the destination file with
475	with mode 0200 and copies the contents of the source file into it	695	mode 0200 and copies the contents of the source file into it using
476	using "aio_sendfile", followed by restoring atime, mtime, access	696	"aio_sendfile", followed by restoring atime, mtime, access mode and
477	mode and uid/gid, in that order.	697	uid/gid, in that order.
478		698
479	If an error occurs, the partial destination file will be unlinked,	699	If an error occurs, the partial destination file will be unlinked,
480	if possible, except when setting atime, mtime, access mode and	700	if possible, except when setting atime, mtime, access mode and
481	uid/gid, where errors are being ignored.	701	uid/gid, where errors are being ignored.
482		702
483	aio_move $srcpath, $dstpath, $callback->($status)	703	aio_move $srcpath, $dstpath, $callback->($status)
484	Try to move the file (directories not supported as either source	704	Try to move the file (directories not supported as either source
485	or destination) from $srcpath to $dstpath and call the callback with	705	or destination) from $srcpath to $dstpath and call the callback with
486	the 0 (error) or -1 ok.	706	a status of 0 (ok) or -1 (error, see $!).
487		707
488	This is a composite request that tries to rename(2) the file first.	708	This is a composite request that tries to rename(2) the file first;
489	If rename files with "EXDEV", it copies the file with "aio_copy"	709	if rename fails with "EXDEV", it copies the file with "aio_copy"
490	and, if that is successful, unlinking the $srcpath.	710	and, if that is successful, unlinks the $srcpath.
491		711
492	aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	712	aio_scandir $pathname, $maxreq, $callback->($dirs, $nondirs)
493	Scans a directory (similar to "aio_readdir") but additionally tries	713	Scans a directory (similar to "aio_readdir") but additionally tries
494	to efficiently separate the entries of directory $path into two sets	714	to efficiently separate the entries of directory $path into two sets
495	of names, directories you can recurse into (directories), and ones	715	of names, directories you can recurse into (directories), and ones
496	you cannot recurse into (everything else, including symlinks to	716	you cannot recurse into (everything else, including symlinks to
497	directories).	717	directories).
…		…
515	Implementation notes.	735	Implementation notes.
516		736
517	The "aio_readdir" cannot be avoided, but "stat()"'ing every entry	737	The "aio_readdir" cannot be avoided, but "stat()"'ing every entry
518	can.	738	can.
519		739
		740	If readdir returns file type information, then this is used directly
		741	to find directories.
		742
520	After reading the directory, the modification time, size etc. of the	743	Otherwise, after reading the directory, the modification time, size
521	directory before and after the readdir is checked, and if they match	744	etc. of the directory before and after the readdir is checked, and
522	(and isn't the current time), the link count will be used to decide	745	if they match (and isn't the current time), the link count will be
523	how many entries are directories (if >= 2). Otherwise, no knowledge	746	used to decide how many entries are directories (if >= 2).
524	of the number of subdirectories will be assumed.	747	Otherwise, no knowledge of the number of subdirectories will be
		748	assumed.
525		749
526	Then entries will be sorted into likely directories (everything	750	Then entries will be sorted into likely directories a non-initial
527	without a non-initial dot currently) and likely non-directories	751	dot currently) and likely non-directories (see "aio_readdirx"). Then
528	(everything else). Then every entry plus an appended "/." will be	752	every entry plus an appended "/." will be "stat"'ed, likely
529	"stat"'ed, likely directories first. If that succeeds, it assumes	753	directories first, in order of their inode numbers. If that
530	that the entry is a directory or a symlink to directory (which will	754	succeeds, it assumes that the entry is a directory or a symlink to
531	be checked seperately). This is often faster than stat'ing the entry	755	directory (which will be checked separately). This is often faster
532	itself because filesystems might detect the type of the entry	756	than stat'ing the entry itself because filesystems might detect the
533	without reading the inode data (e.g. ext2fs filetype feature).	757	type of the entry without reading the inode data (e.g. ext2fs
		758	filetype feature), even on systems that cannot return the filetype
		759	information on readdir.
534		760
535	If the known number of directories (link count - 2) has been	761	If the known number of directories (link count - 2) has been
536	reached, the rest of the entries is assumed to be non-directories.	762	reached, the rest of the entries is assumed to be non-directories.
537		763
538	This only works with certainty on POSIX (= UNIX) filesystems, which	764	This only works with certainty on POSIX (= UNIX) filesystems, which
…		…
540		766
541	It will also likely work on non-POSIX filesystems with reduced	767	It will also likely work on non-POSIX filesystems with reduced
542	efficiency as those tend to return 0 or 1 as link counts, which	768	efficiency as those tend to return 0 or 1 as link counts, which
543	disables the directory counting heuristic.	769	disables the directory counting heuristic.
544		770
545	aio_rmtree $path, $callback->($status)	771	aio_rmtree $pathname, $callback->($status)
546	Delete a directory tree starting (and including) $path, return the	772	Delete a directory tree starting (and including) $path, return the
547	status of the final "rmdir" only. This is a composite request that	773	status of the final "rmdir" only. This is a composite request that
548	uses "aio_scandir" to recurse into and rmdir directories, and unlink	774	uses "aio_scandir" to recurse into and rmdir directories, and unlink
549	everything else.	775	everything else.
550		776
		777	aio_sync $callback->($status)
		778	Asynchronously call sync and call the callback when finished.
		779
551	aio_fsync $fh, $callback->($status)	780	aio_fsync $fh, $callback->($status)
552	Asynchronously call fsync on the given filehandle and call the	781	Asynchronously call fsync on the given filehandle and call the
553	callback with the fsync result code.	782	callback with the fsync result code.
554		783
555	aio_fdatasync $fh, $callback->($status)	784	aio_fdatasync $fh, $callback->($status)
556	Asynchronously call fdatasync on the given filehandle and call the	785	Asynchronously call fdatasync on the given filehandle and call the
557	callback with the fdatasync result code.	786	callback with the fdatasync result code.
558		787
559	If this call isn't available because your OS lacks it or it couldn't	788	If this call isn't available because your OS lacks it or it couldn't
560	be detected, it will be emulated by calling "fsync" instead.	789	be detected, it will be emulated by calling "fsync" instead.
		790
		791	aio_syncfs $fh, $callback->($status)
		792	Asynchronously call the syncfs syscall to sync the filesystem
		793	associated to the given filehandle and call the callback with the
		794	syncfs result code. If syncfs is not available, calls sync(), but
		795	returns -1 and sets errno to "ENOSYS" nevertheless.
		796
		797	aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
		798	Sync the data portion of the file specified by $offset and $length
		799	to disk (but NOT the metadata), by calling the Linux-specific
		800	sync_file_range call. If sync_file_range is not available or it
		801	returns ENOSYS, then fdatasync or fsync is being substituted.
		802
		803	$flags can be a combination of
		804	"IO::AIO::SYNC_FILE_RANGE_WAIT_BEFORE",
		805	"IO::AIO::SYNC_FILE_RANGE_WRITE" and
		806	"IO::AIO::SYNC_FILE_RANGE_WAIT_AFTER": refer to the sync_file_range
		807	manpage for details.
		808
		809	aio_pathsync $pathname, $callback->($status)
		810	This request tries to open, fsync and close the given path. This is
		811	a composite request intended to sync directories after directory
		812	operations (E.g. rename). This might not work on all operating
		813	systems or have any specific effect, but usually it makes sure that
		814	directory changes get written to disc. It works for anything that
		815	can be opened for read-only, not just directories.
		816
		817	Future versions of this function might fall back to other methods
		818	when "fsync" on the directory fails (such as calling "sync").
		819
		820	Passes 0 when everything went ok, and -1 on error.
		821
		822	aio_msync $scalar, $offset = 0, $length = undef, flags = 0,
		823	$callback->($status)
		824	This is a rather advanced IO::AIO call, which only works on
		825	mmap(2)ed scalars (see the "IO::AIO::mmap" function, although it
		826	also works on data scalars managed by the Sys::Mmap or Mmap modules,
		827	note that the scalar must only be modified in-place while an aio
		828	operation is pending on it).
		829
		830	It calls the "msync" function of your OS, if available, with the
		831	memory area starting at $offset in the string and ending $length
		832	bytes later. If $length is negative, counts from the end, and if
		833	$length is "undef", then it goes till the end of the string. The
		834	flags can be a combination of "IO::AIO::MS_ASYNC",
		835	"IO::AIO::MS_INVALIDATE" and "IO::AIO::MS_SYNC".
		836
		837	aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0,
		838	$callback->($status)
		839	This is a rather advanced IO::AIO call, which works best on
		840	mmap(2)ed scalars.
		841
		842	It touches (reads or writes) all memory pages in the specified range
		843	inside the scalar. All caveats and parameters are the same as for
		844	"aio_msync", above, except for flags, which must be either 0 (which
		845	reads all pages and ensures they are instantiated) or
		846	"IO::AIO::MT_MODIFY", which modifies the memory page s(by reading
		847	and writing an octet from it, which dirties the page).
		848
		849	aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
		850	This is a rather advanced IO::AIO call, which works best on
		851	mmap(2)ed scalars.
		852
		853	It reads in all the pages of the underlying storage into memory (if
		854	any) and locks them, so they are not getting swapped/paged out or
		855	removed.
		856
		857	If $length is undefined, then the scalar will be locked till the
		858	end.
		859
		860	On systems that do not implement "mlock", this function returns -1
		861	and sets errno to "ENOSYS".
		862
		863	Note that the corresponding "munlock" is synchronous and is
		864	documented under "MISCELLANEOUS FUNCTIONS".
		865
		866	Example: open a file, mmap and mlock it - both will be undone when
		867	$data gets destroyed.
		868
		869	open my $fh, "<", $path or die "$path: $!";
		870	my $data;
		871	IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;
		872	aio_mlock $data; # mlock in background
		873
		874	aio_mlockall $flags, $callback->($status)
		875	Calls the "mlockall" function with the given $flags (a combination
		876	of "IO::AIO::MCL_CURRENT" and "IO::AIO::MCL_FUTURE").
		877
		878	On systems that do not implement "mlockall", this function returns
		879	-1 and sets errno to "ENOSYS".
		880
		881	Note that the corresponding "munlockall" is synchronous and is
		882	documented under "MISCELLANEOUS FUNCTIONS".
		883
		884	Example: asynchronously lock all current and future pages into
		885	memory.
		886
		887	aio_mlockall IO::AIO::MCL_FUTURE;
		888
		889	aio_fiemap $fh, $start, $length, $flags, $count, $cb->(\@extents)
		890	Queries the extents of the given file (by calling the Linux FIEMAP
		891	ioctl, see <http://cvs.schmorp.de/IO-AIO/doc/fiemap.txt> for
		892	details). If the "ioctl" is not available on your OS, then this
		893	rquiest will fail with "ENOSYS".
		894
		895	$start is the starting offset to query extents for, $length is the
		896	size of the range to query - if it is "undef", then the whole file
		897	will be queried.
		898
		899	$flags is a combination of flags ("IO::AIO::FIEMAP_FLAG_SYNC" or
		900	"IO::AIO::FIEMAP_FLAG_XATTR" - "IO::AIO::FIEMAP_FLAGS_COMPAT" is
		901	also exported), and is normally 0 or "IO::AIO::FIEMAP_FLAG_SYNC" to
		902	query the data portion.
		903
		904	$count is the maximum number of extent records to return. If it is
		905	"undef", then IO::AIO queries all extents of the file. As a very
		906	special case, if it is 0, then the callback receives the number of
		907	extents instead of the extents themselves.
		908
		909	If an error occurs, the callback receives no arguments. The special
		910	"errno" value "IO::AIO::EBADR" is available to test for flag errors.
		911
		912	Otherwise, the callback receives an array reference with extent
		913	structures. Each extent structure is an array reference itself, with
		914	the following members:
		915
		916	[$logical, $physical, $length, $flags]
		917
		918	Flags is any combination of the following flag values (typically
		919	either 0 or "IO::AIO::FIEMAP_EXTENT_LAST"):
		920
		921	"IO::AIO::FIEMAP_EXTENT_LAST", "IO::AIO::FIEMAP_EXTENT_UNKNOWN",
		922	"IO::AIO::FIEMAP_EXTENT_DELALLOC", "IO::AIO::FIEMAP_EXTENT_ENCODED",
		923	"IO::AIO::FIEMAP_EXTENT_DATA_ENCRYPTED",
		924	"IO::AIO::FIEMAP_EXTENT_NOT_ALIGNED",
		925	"IO::AIO::FIEMAP_EXTENT_DATA_INLINE",
		926	"IO::AIO::FIEMAP_EXTENT_DATA_TAIL",
		927	"IO::AIO::FIEMAP_EXTENT_UNWRITTEN", "IO::AIO::FIEMAP_EXTENT_MERGED"
		928	or "IO::AIO::FIEMAP_EXTENT_SHARED".
561		929
562	aio_group $callback->(...)	930	aio_group $callback->(...)
563	This is a very special aio request: Instead of doing something, it	931	This is a very special aio request: Instead of doing something, it
564	is a container for other aio requests, which is useful if you want	932	is a container for other aio requests, which is useful if you want
565	to bundle many requests into a single, composite, request with a	933	to bundle many requests into a single, composite, request with a
…		…
600	requests like sleep and file handle readable/writable, the overhead	968	requests like sleep and file handle readable/writable, the overhead
601	this creates is immense (it blocks a thread for a long time) so do	969	this creates is immense (it blocks a thread for a long time) so do
602	not use this function except to put your application under	970	not use this function except to put your application under
603	artificial I/O pressure.	971	artificial I/O pressure.
604		972
		973	IO::AIO::WD - multiple working directories
		974	Your process only has one current working directory, which is used by
		975	all threads. This makes it hard to use relative paths (some other
		976	component could call "chdir" at any time, and it is hard to control when
		977	the path will be used by IO::AIO).
		978
		979	One solution for this is to always use absolute paths. This usually
		980	works, but can be quite slow (the kernel has to walk the whole path on
		981	every access), and can also be a hassle to implement.
		982
		983	Newer POSIX systems have a number of functions (openat, fdopendir,
		984	futimensat and so on) that make it possible to specify working
		985	directories per operation.
		986
		987	For portability, and because the clowns who "designed", or shall I
		988	write, perpetrated this new interface were obviously half-drunk, this
		989	abstraction cannot be perfect, though.
		990
		991	IO::AIO allows you to convert directory paths into a so-called
		992	IO::AIO::WD object. This object stores the canonicalised, absolute
		993	version of the path, and on systems that allow it, also a directory file
		994	descriptor.
		995
		996	Everywhere where a pathname is accepted by IO::AIO (e.g. in "aio_stat"
		997	or "aio_unlink"), one can specify an array reference with an IO::AIO::WD
		998	object and a pathname instead (or the IO::AIO::WD object alone, which
		999	gets interpreted as "[$wd, "."]"). If the pathname is absolute, the
		1000	IO::AIO::WD object is ignored, otherwise the pathname is resolved
		1001	relative to that IO::AIO::WD object.
		1002
		1003	For example, to get a wd object for /etc and then stat passwd inside,
		1004	you would write:
		1005
		1006	aio_wd "/etc", sub {
		1007	my $etcdir = shift;
		1008
		1009	# although $etcdir can be undef on error, there is generally no reason
		1010	# to check for errors here, as aio_stat will fail with ENOENT
		1011	# when $etcdir is undef.
		1012
		1013	aio_stat [$etcdir, "passwd"], sub {
		1014	# yay
		1015	};
		1016	};
		1017
		1018	That "aio_wd" is a request and not a normal function shows that creating
		1019	an IO::AIO::WD object is itself a potentially blocking operation, which
		1020	is why it is done asynchronously.
		1021
		1022	To stat the directory obtained with "aio_wd" above, one could write
		1023	either of the following three request calls:
		1024
		1025	aio_lstat "/etc" , sub { ... # pathname as normal string
		1026	aio_lstat [$wd, "."], sub { ... # "." relative to $wd (i.e. $wd itself)
		1027	aio_lstat $wd , sub { ... # shorthand for the previous
		1028
		1029	As with normal pathnames, IO::AIO keeps a copy of the working directory
		1030	object and the pathname string, so you could write the following without
		1031	causing any issues due to $path getting reused:
		1032
		1033	my $path = [$wd, undef];
		1034
		1035	for my $name (qw(abc def ghi)) {
		1036	$path->[1] = $name;
		1037	aio_stat $path, sub {
		1038	# ...
		1039	};
		1040	}
		1041
		1042	There are some caveats: when directories get renamed (or deleted), the
		1043	pathname string doesn't change, so will point to the new directory (or
		1044	nowhere at all), while the directory fd, if available on the system,
		1045	will still point to the original directory. Most functions accepting a
		1046	pathname will use the directory fd on newer systems, and the string on
		1047	older systems. Some functions (such as realpath) will always rely on the
		1048	string form of the pathname.
		1049
		1050	So this fucntionality is mainly useful to get some protection against
		1051	"chdir", to easily get an absolute path out of a relative path for
		1052	future reference, and to speed up doing many operations in the same
		1053	directory (e.g. when stat'ing all files in a directory).
		1054
		1055	The following functions implement this working directory abstraction:
		1056
		1057	aio_wd $pathname, $callback->($wd)
		1058	Asynchonously canonicalise the given pathname and convert it to an
		1059	IO::AIO::WD object representing it. If possible and supported on the
		1060	system, also open a directory fd to speed up pathname resolution
		1061	relative to this working directory.
		1062
		1063	If something goes wrong, then "undef" is passwd to the callback
		1064	instead of a working directory object and $! is set appropriately.
		1065	Since passing "undef" as working directory component of a pathname
		1066	fails the request with "ENOENT", there is often no need for error
		1067	checking in the "aio_wd" callback, as future requests using the
		1068	value will fail in the expected way.
		1069
		1070	If this call isn't available because your OS lacks it or it couldn't
		1071	be detected, it will be emulated by calling "fsync" instead.
		1072
		1073	IO::AIO::CWD
		1074	This is a compiletime constant (object) that represents the process
		1075	current working directory.
		1076
		1077	Specifying this object as working directory object for a pathname is
		1078	as if the pathname would be specified directly, without a directory
		1079	object, e.g., these calls are functionally identical:
		1080
		1081	aio_stat "somefile", sub { ... };
		1082	aio_stat [IO::AIO::CWD, "somefile"], sub { ... };
		1083
605	IO::AIO::REQ CLASS	1084	IO::AIO::REQ CLASS
606	All non-aggregate "aio_*" functions return an object of this class when	1085	All non-aggregate "aio_*" functions return an object of this class when
607	called in non-void context.	1086	called in non-void context.
608		1087
609	cancel $req	1088	cancel $req
610	Cancels the request, if possible. Has the effect of skipping	1089	Cancels the request, if possible. Has the effect of skipping
611	execution when entering the execute state and skipping calling the	1090	execution when entering the execute state and skipping calling the
612	callback when entering the the result state, but will leave the	1091	callback when entering the the result state, but will leave the
613	request otherwise untouched. That means that requests that currently	1092	request otherwise untouched (with the exception of readdir). That
614	execute will not be stopped and resources held by the request will	1093	means that requests that currently execute will not be stopped and
615	not be freed prematurely.	1094	resources held by the request will not be freed prematurely.
616		1095
617	cb $req $callback->(...)	1096	cb $req $callback->(...)
618	Replace (or simply set) the callback registered to the request.	1097	Replace (or simply set) the callback registered to the request.
619		1098
620	IO::AIO::GRP CLASS	1099	IO::AIO::GRP CLASS
…		…
647	};	1126	};
648		1127
649	This makes it very easy to create composite requests (see the source of	1128	This makes it very easy to create composite requests (see the source of
650	"aio_move" for an application) that work and feel like simple requests.	1129	"aio_move" for an application) that work and feel like simple requests.
651		1130
652	* The IO::AIO::GRP objects will be cleaned up during calls to	1131	* The IO::AIO::GRP objects will be cleaned up during calls to
653	"IO::AIO::poll_cb", just like any other request.	1132	"IO::AIO::poll_cb", just like any other request.
		1133
654	* They can be canceled like any other request. Canceling will cancel not	1134	* They can be canceled like any other request. Canceling will cancel
655	only the request itself, but also all requests it contains.	1135	not only the request itself, but also all requests it contains.
		1136
656	* They can also can also be added to other IO::AIO::GRP objects.	1137	* They can also can also be added to other IO::AIO::GRP objects.
		1138
657	* You must not add requests to a group from within the group callback	1139	* You must not add requests to a group from within the group callback
658	(or any later time).	1140	(or any later time).
659		1141
660	Their lifetime, simplified, looks like this: when they are empty, they	1142	Their lifetime, simplified, looks like this: when they are empty, they
661	will finish very quickly. If they contain only requests that are in the	1143	will finish very quickly. If they contain only requests that are in the
662	"done" state, they will also finish. Otherwise they will continue to	1144	"done" state, they will also finish. Otherwise they will continue to
663	exist.	1145	exist.
664		1146
665	That means after creating a group you have some time to add requests.	1147	That means after creating a group you have some time to add requests
666	And in the callbacks of those requests, you can add further requests to	1148	(precisely before the callback has been invoked, which is only done
667	the group. And only when all those requests have finished will the the	1149	within the "poll_cb"). And in the callbacks of those requests, you can
668	group itself finish.	1150	add further requests to the group. And only when all those requests have
		1151	finished will the the group itself finish.
669		1152
670	add $grp ...	1153	add $grp ...
671	$grp->add (...)	1154	$grp->add (...)
672	Add one or more requests to the group. Any type of IO::AIO::REQ can	1155	Add one or more requests to the group. Any type of IO::AIO::REQ can
673	be added, including other groups, as long as you do not create	1156	be added, including other groups, as long as you do not create
…		…
678	$grp->cancel_subs	1161	$grp->cancel_subs
679	Cancel all subrequests and clears any feeder, but not the group	1162	Cancel all subrequests and clears any feeder, but not the group
680	request itself. Useful when you queued a lot of events but got a	1163	request itself. Useful when you queued a lot of events but got a
681	result early.	1164	result early.
682		1165
		1166	The group request will finish normally (you cannot add requests to
		1167	the group).
		1168
683	$grp->result (...)	1169	$grp->result (...)
684	Set the result value(s) that will be passed to the group callback	1170	Set the result value(s) that will be passed to the group callback
685	when all subrequests have finished and set thre groups errno to the	1171	when all subrequests have finished and set the groups errno to the
686	current value of errno (just like calling "errno" without an error	1172	current value of errno (just like calling "errno" without an error
687	number). By default, no argument will be passed and errno is zero.	1173	number). By default, no argument will be passed and errno is zero.
688		1174
689	$grp->errno ([$errno])	1175	$grp->errno ([$errno])
690	Sets the group errno value to $errno, or the current value of errno	1176	Sets the group errno value to $errno, or the current value of errno
…		…
701	Sets a feeder/generator on this group: every group can have an	1187	Sets a feeder/generator on this group: every group can have an
702	attached generator that generates requests if idle. The idea behind	1188	attached generator that generates requests if idle. The idea behind
703	this is that, although you could just queue as many requests as you	1189	this is that, although you could just queue as many requests as you
704	want in a group, this might starve other requests for a potentially	1190	want in a group, this might starve other requests for a potentially
705	long time. For example, "aio_scandir" might generate hundreds of	1191	long time. For example, "aio_scandir" might generate hundreds of
706	thousands "aio_stat" requests, delaying any later requests for a	1192	thousands of "aio_stat" requests, delaying any later requests for a
707	long time.	1193	long time.
708		1194
709	To avoid this, and allow incremental generation of requests, you can	1195	To avoid this, and allow incremental generation of requests, you can
710	instead a group and set a feeder on it that generates those	1196	instead a group and set a feeder on it that generates those
711	requests. The feed callback will be called whenever there are few	1197	requests. The feed callback will be called whenever there are few
…		…
716	does not impose any limits).	1202	does not impose any limits).
717		1203
718	If the feed does not queue more requests when called, it will be	1204	If the feed does not queue more requests when called, it will be
719	automatically removed from the group.	1205	automatically removed from the group.
720		1206
721	If the feed limit is 0, it will be set to 2 automatically.	1207	If the feed limit is 0 when this method is called, it will be set to
		1208	2 automatically.
722		1209
723	Example:	1210	Example:
724		1211
725	# stat all files in @files, but only ever use four aio requests concurrently:	1212	# stat all files in @files, but only ever use four aio requests concurrently:
726		1213
…		…
737	Sets the feeder limit for the group: The feeder will be called	1224	Sets the feeder limit for the group: The feeder will be called
738	whenever the group contains less than this many requests.	1225	whenever the group contains less than this many requests.
739		1226
740	Setting the limit to 0 will pause the feeding process.	1227	Setting the limit to 0 will pause the feeding process.
741		1228
		1229	The default value for the limit is 0, but note that setting a feeder
		1230	automatically bumps it up to 2.
		1231
742	SUPPORT FUNCTIONS	1232	SUPPORT FUNCTIONS
743	EVENT PROCESSING AND EVENT LOOP INTEGRATION	1233	EVENT PROCESSING AND EVENT LOOP INTEGRATION
744	$fileno = IO::AIO::poll_fileno	1234	$fileno = IO::AIO::poll_fileno
745	Return the request result pipe file descriptor. This filehandle	1235	Return the request result pipe file descriptor. This filehandle
746	must be polled for reading by some mechanism outside this module	1236	must be polled for reading by some mechanism outside this module
747	(e.g. Event or select, see below or the SYNOPSIS). If the pipe	1237	(e.g. EV, Glib, select and so on, see below or the SYNOPSIS). If the
748	becomes readable you have to call "poll_cb" to check the results.	1238	pipe becomes readable you have to call "poll_cb" to check the
		1239	results.
749		1240
750	See "poll_cb" for an example.	1241	See "poll_cb" for an example.
751		1242
752	IO::AIO::poll_cb	1243	IO::AIO::poll_cb
753	Process some outstanding events on the result pipe. You have to call	1244	Process some outstanding events on the result pipe. You have to call
754	this regularly. Returns the number of events processed. Returns	1245	this regularly. Returns 0 if all events could be processed (or there
755	immediately when no events are outstanding. The amount of events	1246	were no events to process), or -1 if it returned earlier for
756	processed depends on the settings of "IO::AIO::max_poll_req" and	1247	whatever reason. Returns immediately when no events are outstanding.
757	"IO::AIO::max_poll_time".	1248	The amount of events processed depends on the settings of
		1249	"IO::AIO::max_poll_req" and "IO::AIO::max_poll_time".
758		1250
759	If not all requests were processed for whatever reason, the	1251	If not all requests were processed for whatever reason, the
760	filehandle will still be ready when "poll_cb" returns.	1252	filehandle will still be ready when "poll_cb" returns, so normally
		1253	you don't have to do anything special to have it called later.
		1254
		1255	Apart from calling "IO::AIO::poll_cb" when the event filehandle
		1256	becomes ready, it can be beneficial to call this function from loops
		1257	which submit a lot of requests, to make sure the results get
		1258	processed when they become available and not just when the loop is
		1259	finished and the event loop takes over again. This function returns
		1260	very fast when there are no outstanding requests.
761		1261
762	Example: Install an Event watcher that automatically calls	1262	Example: Install an Event watcher that automatically calls
763	IO::AIO::poll_cb with high priority:	1263	IO::AIO::poll_cb with high priority (more examples can be found in
		1264	the SYNOPSIS section, at the top of this document):
764		1265
765	Event->io (fd => IO::AIO::poll_fileno,	1266	Event->io (fd => IO::AIO::poll_fileno,
766	poll => 'r', async => 1,	1267	poll => 'r', async => 1,
767	cb => \&IO::AIO::poll_cb);	1268	cb => \&IO::AIO::poll_cb);
		1269
		1270	IO::AIO::poll_wait
		1271	If there are any outstanding requests and none of them in the result
		1272	phase, wait till the result filehandle becomes ready for reading
		1273	(simply does a "select" on the filehandle. This is useful if you
		1274	want to synchronously wait for some requests to finish).
		1275
		1276	See "nreqs" for an example.
		1277
		1278	IO::AIO::poll
		1279	Waits until some requests have been handled.
		1280
		1281	Returns the number of requests processed, but is otherwise strictly
		1282	equivalent to:
		1283
		1284	IO::AIO::poll_wait, IO::AIO::poll_cb
		1285
		1286	IO::AIO::flush
		1287	Wait till all outstanding AIO requests have been handled.
		1288
		1289	Strictly equivalent to:
		1290
		1291	IO::AIO::poll_wait, IO::AIO::poll_cb
		1292	while IO::AIO::nreqs;
768		1293
769	IO::AIO::max_poll_reqs $nreqs	1294	IO::AIO::max_poll_reqs $nreqs
770	IO::AIO::max_poll_time $seconds	1295	IO::AIO::max_poll_time $seconds
771	These set the maximum number of requests (default 0, meaning	1296	These set the maximum number of requests (default 0, meaning
772	infinity) that are being processed by "IO::AIO::poll_cb" in one	1297	infinity) that are being processed by "IO::AIO::poll_cb" in one
…		…
796	# use a low priority so other tasks have priority	1321	# use a low priority so other tasks have priority
797	Event->io (fd => IO::AIO::poll_fileno,	1322	Event->io (fd => IO::AIO::poll_fileno,
798	poll => 'r', nice => 1,	1323	poll => 'r', nice => 1,
799	cb => &IO::AIO::poll_cb);	1324	cb => &IO::AIO::poll_cb);
800		1325
801	IO::AIO::poll_wait
802	If there are any outstanding requests and none of them in the result
803	phase, wait till the result filehandle becomes ready for reading
804	(simply does a "select" on the filehandle. This is useful if you
805	want to synchronously wait for some requests to finish).
806
807	See "nreqs" for an example.
808
809	IO::AIO::poll
810	Waits until some requests have been handled.
811
812	Returns the number of requests processed, but is otherwise strictly
813	equivalent to:
814
815	IO::AIO::poll_wait, IO::AIO::poll_cb
816
817	IO::AIO::flush
818	Wait till all outstanding AIO requests have been handled.
819
820	Strictly equivalent to:
821
822	IO::AIO::poll_wait, IO::AIO::poll_cb
823	while IO::AIO::nreqs;
824
825	CONTROLLING THE NUMBER OF THREADS	1326	CONTROLLING THE NUMBER OF THREADS
826	IO::AIO::min_parallel $nthreads	1327	IO::AIO::min_parallel $nthreads
827	Set the minimum number of AIO threads to $nthreads. The current	1328	Set the minimum number of AIO threads to $nthreads. The current
828	default is 8, which means eight asynchronous operations can execute	1329	default is 8, which means eight asynchronous operations can execute
829	concurrently at any one time (the number of outstanding requests,	1330	concurrently at any one time (the number of outstanding requests,
…		…
858		1359
859	Under normal circumstances you don't need to call this function.	1360	Under normal circumstances you don't need to call this function.
860		1361
861	IO::AIO::max_idle $nthreads	1362	IO::AIO::max_idle $nthreads
862	Limit the number of threads (default: 4) that are allowed to idle	1363	Limit the number of threads (default: 4) that are allowed to idle
863	(i.e., threads that did not get a request to process within 10	1364	(i.e., threads that did not get a request to process within the idle
864	seconds). That means if a thread becomes idle while $nthreads other	1365	timeout (default: 10 seconds). That means if a thread becomes idle
865	threads are also idle, it will free its resources and exit.	1366	while $nthreads other threads are also idle, it will free its
		1367	resources and exit.
866		1368
867	This is useful when you allow a large number of threads (e.g. 100 or	1369	This is useful when you allow a large number of threads (e.g. 100 or
868	1000) to allow for extremely high load situations, but want to free	1370	1000) to allow for extremely high load situations, but want to free
869	resources under normal circumstances (1000 threads can easily	1371	resources under normal circumstances (1000 threads can easily
870	consume 30MB of RAM).	1372	consume 30MB of RAM).
871		1373
872	The default is probably ok in most situations, especially if thread	1374	The default is probably ok in most situations, especially if thread
873	creation is fast. If thread creation is very slow on your system you	1375	creation is fast. If thread creation is very slow on your system you
874	might want to use larger values.	1376	might want to use larger values.
875		1377
		1378	IO::AIO::idle_timeout $seconds
		1379	Sets the minimum idle timeout (default 10) after which worker
		1380	threads are allowed to exit. SEe "IO::AIO::max_idle".
		1381
876	$oldmaxreqs = IO::AIO::max_outstanding $maxreqs	1382	IO::AIO::max_outstanding $maxreqs
		1383	Sets the maximum number of outstanding requests to $nreqs. If you do
		1384	queue up more than this number of requests, the next call to
		1385	"IO::AIO::poll_cb" (and other functions calling "poll_cb", such as
		1386	"IO::AIO::flush" or "IO::AIO::poll") will block until the limit is
		1387	no longer exceeded.
		1388
		1389	In other words, this setting does not enforce a queue limit, but can
		1390	be used to make poll functions block if the limit is exceeded.
		1391
877	This is a very bad function to use in interactive programs because	1392	This is a very bad function to use in interactive programs because
878	it blocks, and a bad way to reduce concurrency because it is	1393	it blocks, and a bad way to reduce concurrency because it is
879	inexact: Better use an "aio_group" together with a feed callback.	1394	inexact: Better use an "aio_group" together with a feed callback.
880		1395
881	Sets the maximum number of outstanding requests to $nreqs. If you do	1396	It's main use is in scripts without an event loop - when you want to
882	queue up more than this number of requests, the next call to the	1397	stat a lot of files, you can write somehting like this:
883	"poll_cb" (and "poll_some" and other functions calling "poll_cb")
884	function will block until the limit is no longer exceeded.
885		1398
886	The default value is very large, so there is no practical limit on	1399	IO::AIO::max_outstanding 32;
		1400
		1401	for my $path (...) {
		1402	aio_stat $path , ...;
		1403	IO::AIO::poll_cb;
		1404	}
		1405
		1406	IO::AIO::flush;
		1407
		1408	The call to "poll_cb" inside the loop will normally return
		1409	instantly, but as soon as more thna 32 reqeusts are in-flight, it
		1410	will block until some requests have been handled. This keeps the
		1411	loop from pushing a large number of "aio_stat" requests onto the
		1412	queue.
		1413
		1414	The default value for "max_outstanding" is very large, so there is
887	the number of outstanding requests.	1415	no practical limit on the number of outstanding requests.
888
889	You can still queue as many requests as you want. Therefore,
890	"max_oustsanding" is mainly useful in simple scripts (with low
891	values) or as a stop gap to shield against fatal memory overflow
892	(with large values).
893		1416
894	STATISTICAL INFORMATION	1417	STATISTICAL INFORMATION
895	IO::AIO::nreqs	1418	IO::AIO::nreqs
896	Returns the number of requests currently in the ready, execute or	1419	Returns the number of requests currently in the ready, execute or
897	pending states (i.e. for which their callback has not been invoked	1420	pending states (i.e. for which their callback has not been invoked
…		…
908		1431
909	IO::AIO::npending	1432	IO::AIO::npending
910	Returns the number of requests currently in the pending state	1433	Returns the number of requests currently in the pending state
911	(executed, but not yet processed by poll_cb).	1434	(executed, but not yet processed by poll_cb).
912		1435
		1436	MISCELLANEOUS FUNCTIONS
		1437	IO::AIO implements some functions that might be useful, but are not
		1438	asynchronous.
		1439
		1440	IO::AIO::sendfile $ofh, $ifh, $offset, $count
		1441	Calls the "eio_sendfile_sync" function, which is like
		1442	"aio_sendfile", but is blocking (this makes most sense if you know
		1443	the input data is likely cached already and the output filehandle is
		1444	set to non-blocking operations).
		1445
		1446	Returns the number of bytes copied, or -1 on error.
		1447
		1448	IO::AIO::fadvise $fh, $offset, $len, $advice
		1449	Simply calls the "posix_fadvise" function (see its manpage for
		1450	details). The following advice constants are available:
		1451	"IO::AIO::FADV_NORMAL", "IO::AIO::FADV_SEQUENTIAL",
		1452	"IO::AIO::FADV_RANDOM", "IO::AIO::FADV_NOREUSE",
		1453	"IO::AIO::FADV_WILLNEED", "IO::AIO::FADV_DONTNEED".
		1454
		1455	On systems that do not implement "posix_fadvise", this function
		1456	returns ENOSYS, otherwise the return value of "posix_fadvise".
		1457
		1458	IO::AIO::madvise $scalar, $offset, $len, $advice
		1459	Simply calls the "posix_madvise" function (see its manpage for
		1460	details). The following advice constants are available:
		1461	"IO::AIO::MADV_NORMAL", "IO::AIO::MADV_SEQUENTIAL",
		1462	"IO::AIO::MADV_RANDOM", "IO::AIO::MADV_WILLNEED",
		1463	"IO::AIO::MADV_DONTNEED".
		1464
		1465	On systems that do not implement "posix_madvise", this function
		1466	returns ENOSYS, otherwise the return value of "posix_madvise".
		1467
		1468	IO::AIO::mprotect $scalar, $offset, $len, $protect
		1469	Simply calls the "mprotect" function on the preferably AIO::mmap'ed
		1470	$scalar (see its manpage for details). The following protect
		1471	constants are available: "IO::AIO::PROT_NONE", "IO::AIO::PROT_READ",
		1472	"IO::AIO::PROT_WRITE", "IO::AIO::PROT_EXEC".
		1473
		1474	On systems that do not implement "mprotect", this function returns
		1475	ENOSYS, otherwise the return value of "mprotect".
		1476
		1477	IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
		1478	Memory-maps a file (or anonymous memory range) and attaches it to
		1479	the given $scalar, which will act like a string scalar.
		1480
		1481	The only operations allowed on the scalar are "substr"/"vec" that
		1482	don't change the string length, and most read-only operations such
		1483	as copying it or searching it with regexes and so on.
		1484
		1485	Anything else is unsafe and will, at best, result in memory leaks.
		1486
		1487	The memory map associated with the $scalar is automatically removed
		1488	when the $scalar is destroyed, or when the "IO::AIO::mmap" or
		1489	"IO::AIO::munmap" functions are called.
		1490
		1491	This calls the "mmap"(2) function internally. See your system's
		1492	manual page for details on the $length, $prot and $flags parameters.
		1493
		1494	The $length must be larger than zero and smaller than the actual
		1495	filesize.
		1496
		1497	$prot is a combination of "IO::AIO::PROT_NONE",
		1498	"IO::AIO::PROT_EXEC", "IO::AIO::PROT_READ" and/or
		1499	"IO::AIO::PROT_WRITE",
		1500
		1501	$flags can be a combination of "IO::AIO::MAP_SHARED" or
		1502	"IO::AIO::MAP_PRIVATE", or a number of system-specific flags (when
		1503	not available, the are defined as 0): "IO::AIO::MAP_ANONYMOUS"
		1504	(which is set to "MAP_ANON" if your system only provides this
		1505	constant), "IO::AIO::MAP_HUGETLB", "IO::AIO::MAP_LOCKED",
		1506	"IO::AIO::MAP_NORESERVE", "IO::AIO::MAP_POPULATE" or
		1507	"IO::AIO::MAP_NONBLOCK"
		1508
		1509	If $fh is "undef", then a file descriptor of -1 is passed.
		1510
		1511	$offset is the offset from the start of the file - it generally must
		1512	be a multiple of "IO::AIO::PAGESIZE" and defaults to 0.
		1513
		1514	Example:
		1515
		1516	use Digest::MD5;
		1517	use IO::AIO;
		1518
		1519	open my $fh, "<verybigfile"
		1520	or die "$!";
		1521
		1522	IO::AIO::mmap my $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh
		1523	or die "verybigfile: $!";
		1524
		1525	my $fast_md5 = md5 $data;
		1526
		1527	IO::AIO::munmap $scalar
		1528	Removes a previous mmap and undefines the $scalar.
		1529
		1530	IO::AIO::munlock $scalar, $offset = 0, $length = undef
		1531	Calls the "munlock" function, undoing the effects of a previous
		1532	"aio_mlock" call (see its description for details).
		1533
		1534	IO::AIO::munlockall
		1535	Calls the "munlockall" function.
		1536
		1537	On systems that do not implement "munlockall", this function returns
		1538	ENOSYS, otherwise the return value of "munlockall".
		1539
		1540	IO::AIO::splice $r_fh, $r_off, $w_fh, $w_off, $length, $flags
		1541	Calls the GNU/Linux splice(2) syscall, if available. If $r_off or
		1542	$w_off are "undef", then "NULL" is passed for these, otherwise they
		1543	should be the file offset.
		1544
		1545	The following symbol flag values are available:
		1546	"IO::AIO::SPLICE_F_MOVE", "IO::AIO::SPLICE_F_NONBLOCK",
		1547	"IO::AIO::SPLICE_F_MORE" and "IO::AIO::SPLICE_F_GIFT".
		1548
		1549	See the splice(2) manpage for details.
		1550
		1551	IO::AIO::tee $r_fh, $w_fh, $length, $flags
		1552	Calls the GNU/Linux tee(2) syscall, see it's manpage and the
		1553	description for "IO::AIO::splice" above for details.
		1554
		1555	EVENT LOOP INTEGRATION
		1556	It is recommended to use AnyEvent::AIO to integrate IO::AIO
		1557	automatically into many event loops:
		1558
		1559	# AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...)
		1560	use AnyEvent::AIO;
		1561
		1562	You can also integrate IO::AIO manually into many event loops, here are
		1563	some examples of how to do this:
		1564
		1565	# EV integration
		1566	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
		1567
		1568	# Event integration
		1569	Event->io (fd => IO::AIO::poll_fileno,
		1570	poll => 'r',
		1571	cb => \&IO::AIO::poll_cb);
		1572
		1573	# Glib/Gtk2 integration
		1574	add_watch Glib::IO IO::AIO::poll_fileno,
		1575	in => sub { IO::AIO::poll_cb; 1 };
		1576
		1577	# Tk integration
		1578	Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
		1579	readable => \&IO::AIO::poll_cb);
		1580
		1581	# Danga::Socket integration
		1582	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
		1583	\&IO::AIO::poll_cb);
		1584
913	FORK BEHAVIOUR	1585	FORK BEHAVIOUR
914	This module should do "the right thing" when the process using it forks:	1586	Usage of pthreads in a program changes the semantics of fork
		1587	considerably. Specifically, only async-safe functions can be called
		1588	after fork. Perl doesn't know about this, so in general, you cannot call
		1589	fork with defined behaviour in perl if pthreads are involved. IO::AIO
		1590	uses pthreads, so this applies, but many other extensions and (for
		1591	inexplicable reasons) perl itself often is linked against pthreads, so
		1592	this limitation applies to quite a lot of perls.
915		1593
916	Before the fork, IO::AIO enters a quiescent state where no requests can	1594	This module no longer tries to fight your OS, or POSIX. That means
917	be added in other threads and no results will be processed. After the	1595	IO::AIO only works in the process that loaded it. Forking is fully
918	fork the parent simply leaves the quiescent state and continues	1596	supported, but using IO::AIO in the child is not.
919	request/result processing, while the child frees the request/result
920	queue (so that the requests started before the fork will only be handled
921	in the parent). Threads will be started on demand until the limit set in
922	the parent process has been reached again.
923		1597
924	In short: the parent will, after a short pause, continue as if fork had	1598	You might get around by not using IO::AIO before (or after) forking.
925	not been called, while the child will act as if IO::AIO has not been	1599	You could also try to call the IO::AIO::reinit function in the child:
926	used yet.	1600
		1601	IO::AIO::reinit
		1602	Abandons all current requests and I/O threads and simply
		1603	reinitialises all data structures. This is not an operation
		1604	supported by any standards, but happens to work on GNU/Linux and
		1605	some newer BSD systems.
		1606
		1607	The only reasonable use for this function is to call it after
		1608	forking, if "IO::AIO" was used in the parent. Calling it while
		1609	IO::AIO is active in the process will result in undefined behaviour.
		1610	Calling it at any time will also result in any undefined (by POSIX)
		1611	behaviour.
927		1612
928	MEMORY USAGE	1613	MEMORY USAGE
929	Per-request usage:	1614	Per-request usage:
930		1615
931	Each aio request uses - depending on your architecture - around 100-200	1616	Each aio request uses - depending on your architecture - around 100-200
…		…
945		1630
946	KNOWN BUGS	1631	KNOWN BUGS
947	Known bugs will be fixed in the next release.	1632	Known bugs will be fixed in the next release.
948		1633
949	SEE ALSO	1634	SEE ALSO
950	Coro::AIO.	1635	AnyEvent::AIO for easy integration into event loops, Coro::AIO for a
		1636	more natural syntax.
951		1637
952	AUTHOR	1638	AUTHOR
953	Marc Lehmann <schmorp@schmorp.de>	1639	Marc Lehmann <schmorp@schmorp.de>
954	http://home.schmorp.de/	1640	http://home.schmorp.de/
955		1641

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Comparing IO-AIO/README (file contents): Revision 1.27 by root, Sat Oct 6 14:05:37 2007 UTC vs. Revision 1.52 by root, Tue Apr 10 05:01:33 2012 UTC

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Comparing IO-AIO/README (file contents):
Revision 1.27 by root, Sat Oct 6 14:05:37 2007 UTC vs.
Revision 1.52 by root, Tue Apr 10 05:01:33 2012 UTC