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

Comparing IO-AIO/README (file contents):
Revision 1.34 by root, Thu Nov 20 09:01:40 2008 UTC vs.
Revision 1.48 by root, Wed Jun 29 11:25:17 2011 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 (EV, Event, Glib, Tk, POE, urxvt, pureperl...)
30	use AnyEvent::AIO;
31
32	# EV integration
33	my $w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
34
35	# Event integration
36	Event->io (fd => IO::AIO::poll_fileno,
37	poll => 'r',
38	cb => \&IO::AIO::poll_cb);
39
40	# Glib/Gtk2 integration
41	add_watch Glib::IO IO::AIO::poll_fileno,
42	in => sub { IO::AIO::poll_cb; 1 };
43
44	# Tk integration
45	Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
46	readable => \&IO::AIO::poll_cb);
47
48	# Danga::Socket integration
49	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
50	\&IO::AIO::poll_cb);
51
52	DESCRIPTION	29	DESCRIPTION
53	This module implements asynchronous I/O using whatever means your	30	This module implements asynchronous I/O using whatever means your
54	operating system supports.	31	operating system supports. It is implemented as an interface to "libeio"
		32	(<http://software.schmorp.de/pkg/libeio.html>).
55		33
56	Asynchronous means that operations that can normally block your program	34	Asynchronous means that operations that can normally block your program
57	(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
58	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
59	extremely useful for programs that need to stay interactive even when	37	extremely useful for programs that need to stay interactive even when
…		…
64	operations concurrently.	42	operations concurrently.
65		43
66	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
67	sockets), using these functions on file descriptors that support	45	sockets), using these functions on file descriptors that support
68	nonblocking operation (again, sockets, pipes etc.) is very inefficient.	46	nonblocking operation (again, sockets, pipes etc.) is very inefficient.
69	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
70	naturally fit into such an event loop itself.	48	naturally fit into such an event loop itself.
71		49
72	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
73	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
74	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
…		…
83	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
84	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
85	call "poll_cb" (or other "aio_" functions) recursively.	63	call "poll_cb" (or other "aio_" functions) recursively.
86		64
87	EXAMPLE	65	EXAMPLE
88	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
89	/etc/passwd asynchronously:	67	asynchronously:
90		68
91	use Fcntl;	69	use Fcntl;
92	use Event;	70	use EV;
93	use IO::AIO;	71	use IO::AIO;
94		72
95	# register the IO::AIO callback with Event	73	# register the IO::AIO callback with EV
96	Event->io (fd => IO::AIO::poll_fileno,	74	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
97	poll => 'r',
98	cb => \&IO::AIO::poll_cb);
99		75
100	# queue the request to open /etc/passwd	76	# queue the request to open /etc/passwd
101	aio_open "/etc/passwd", O_RDONLY, 0, sub {	77	aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
102	my $fh = shift	78	my $fh = shift
103	or die "error while opening: $!";	79	or die "error while opening: $!";
104		80
105	# stat'ing filehandles is generally non-blocking	81	# stat'ing filehandles is generally non-blocking
106	my $size = -s $fh;	82	my $size = -s $fh;
…		…
115		91
116	# file contents now in $contents	92	# file contents now in $contents
117	print $contents;	93	print $contents;
118		94
119	# exit event loop and program	95	# exit event loop and program
120	Event::unloop;	96	EV::unloop;
121	};	97	};
122	};	98	};
123		99
124	# possibly queue up other requests, or open GUI windows,	100	# possibly queue up other requests, or open GUI windows,
125	# check for sockets etc. etc.	101	# check for sockets etc. etc.
126		102
127	# process events as long as there are some:	103	# process events as long as there are some:
128	Event::loop;	104	EV::loop;
129		105
130	REQUEST ANATOMY AND LIFETIME	106	REQUEST ANATOMY AND LIFETIME
131	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
132	not directly visible to Perl.	108	not directly visible to Perl.
133		109
…		…
169	anymore (except possibly for the Perl object, but its connection to	145	anymore (except possibly for the Perl object, but its connection to
170	the actual aio request is severed and calling its methods will	146	the actual aio request is severed and calling its methods will
171	either do nothing or result in a runtime error).	147	either do nothing or result in a runtime error).
172		148
173	FUNCTIONS	149	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_open $pathname, $flags, $mode, $callback->($fh)
		156	aio_close $fh, $callback->($status)
		157	aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
		158	aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
		159	aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
		160	aio_readahead $fh,$offset,$length, $callback->($retval)
		161	aio_stat $fh_or_path, $callback->($status)
		162	aio_lstat $fh, $callback->($status)
		163	aio_statvfs $fh_or_path, $callback->($statvfs)
		164	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
		165	aio_chown $fh_or_path, $uid, $gid, $callback->($status)
		166	aio_truncate $fh_or_path, $offset, $callback->($status)
		167	aio_chmod $fh_or_path, $mode, $callback->($status)
		168	aio_unlink $pathname, $callback->($status)
		169	aio_mknod $path, $mode, $dev, $callback->($status)
		170	aio_link $srcpath, $dstpath, $callback->($status)
		171	aio_symlink $srcpath, $dstpath, $callback->($status)
		172	aio_readlink $path, $callback->($link)
		173	aio_rename $srcpath, $dstpath, $callback->($status)
		174	aio_mkdir $pathname, $mode, $callback->($status)
		175	aio_rmdir $pathname, $callback->($status)
		176	aio_readdir $pathname, $callback->($entries)
		177	aio_readdirx $pathname, $flags, $callback->($entries, $flags)
		178	IO::AIO::READDIR_DENTS IO::AIO::READDIR_DIRS_FIRST
		179	IO::AIO::READDIR_STAT_ORDER IO::AIO::READDIR_FOUND_UNKNOWN
		180	aio_load $path, $data, $callback->($status)
		181	aio_copy $srcpath, $dstpath, $callback->($status)
		182	aio_move $srcpath, $dstpath, $callback->($status)
		183	aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
		184	aio_rmtree $path, $callback->($status)
		185	aio_sync $callback->($status)
		186	aio_fsync $fh, $callback->($status)
		187	aio_fdatasync $fh, $callback->($status)
		188	aio_sync_file_range $fh, $offset, $nbytes, $flags, $callback->($status)
		189	aio_pathsync $path, $callback->($status)
		190	aio_msync $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		191	aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0, $callback->($status)
		192	aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
		193	aio_mlockall $flags, $callback->($status)
		194	aio_group $callback->(...)
		195	aio_nop $callback->()
		196
		197	$prev_pri = aioreq_pri [$pri]
		198	aioreq_nice $pri_adjust
		199
		200	IO::AIO::poll_wait
		201	IO::AIO::poll_cb
		202	IO::AIO::poll
		203	IO::AIO::flush
		204	IO::AIO::max_poll_reqs $nreqs
		205	IO::AIO::max_poll_time $seconds
		206	IO::AIO::min_parallel $nthreads
		207	IO::AIO::max_parallel $nthreads
		208	IO::AIO::max_idle $nthreads
		209	IO::AIO::idle_timeout $seconds
		210	IO::AIO::max_outstanding $maxreqs
		211	IO::AIO::nreqs
		212	IO::AIO::nready
		213	IO::AIO::npending
		214
		215	IO::AIO::sendfile $ofh, $ifh, $offset, $count
		216	IO::AIO::fadvise $fh, $offset, $len, $advice
		217	IO::AIO::madvise $scalar, $offset, $length, $advice
		218	IO::AIO::mprotect $scalar, $offset, $length, $protect
		219	IO::AIO::munlock $scalar, $offset = 0, $length = undef
		220	IO::AIO::munlockall
		221
174	AIO REQUEST FUNCTIONS	222	AIO REQUEST FUNCTIONS
175	All the "aio_*" calls are more or less thin wrappers around the syscall	223	All the "aio_*" calls are more or less thin wrappers around the syscall
176	with the same name (sans "aio_"). The arguments are similar or	224	with the same name (sans "aio_"). The arguments are similar or
177	identical, and they all accept an additional (and optional) $callback	225	identical, and they all accept an additional (and optional) $callback
178	argument which must be a code reference. This code reference will get	226	argument which must be a code reference. This code reference will get
…		…
249	will be modified by the umask in effect then the request is being	297	will be modified by the umask in effect then the request is being
250	executed, so better never change the umask.	298	executed, so better never change the umask.
251		299
252	Example:	300	Example:
253		301
254	aio_open "/etc/passwd", O_RDONLY, 0, sub {	302	aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
255	if ($_[0]) {	303	if ($_[0]) {
256	print "open successful, fh is $_[0]\n";	304	print "open successful, fh is $_[0]\n";
257	...	305	...
258	} else {	306	} else {
259	die "open failed: $!\n";	307	die "open failed: $!\n";
260	}	308	}
261	};	309	};
262		310
		311	In addition to all the common open modes/flags ("O_RDONLY",
		312	"O_WRONLY", "O_RDWR", "O_CREAT", "O_TRUNC", "O_EXCL" and
		313	"O_APPEND"), the following POSIX and non-POSIX constants are
		314	available (missing ones on your system are, as usual, 0):
		315
		316	"O_ASYNC", "O_DIRECT", "O_NOATIME", "O_CLOEXEC", "O_NOCTTY",
		317	"O_NOFOLLOW", "O_NONBLOCK", "O_EXEC", "O_SEARCH", "O_DIRECTORY",
		318	"O_DSYNC", "O_RSYNC", "O_SYNC" and "O_TTY_INIT".
		319
263	aio_close $fh, $callback->($status)	320	aio_close $fh, $callback->($status)
264	Asynchronously close a file and call the callback with the result	321	Asynchronously close a file and call the callback with the result
265	code.	322	code.
266		323
267	Unfortunately, you can't do this to perl. Perl insists very	324	Unfortunately, you can't do this to perl. Perl insists very
…		…
275	Or in other words: the file descriptor will be closed, but it will	332	Or in other words: the file descriptor will be closed, but it will
276	not be free for reuse until the perl filehandle is closed.	333	not be free for reuse until the perl filehandle is closed.
277		334
278	aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	335	aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
279	aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	336	aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
280	Reads or writes $length bytes from the specified $fh and $offset	337	Reads or writes $length bytes from or to the specified $fh and
281	into the scalar given by $data and offset $dataoffset and calls the	338	$offset into the scalar given by $data and offset $dataoffset and
282	callback without the actual number of bytes read (or -1 on error,	339	calls the callback without the actual number of bytes read (or -1 on
283	just like the syscall).	340	error, just like the syscall).
		341
		342	"aio_read" will, like "sysread", shrink or grow the $data scalar to
		343	offset plus the actual number of bytes read.
284		344
285	If $offset is undefined, then the current file descriptor offset	345	If $offset is undefined, then the current file descriptor offset
286	will be used (and updated), otherwise the file descriptor offset	346	will be used (and updated), otherwise the file descriptor offset
287	will not be changed by these calls.	347	will not be changed by these calls.
288		348
…		…
307	aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)	367	aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
308	Tries to copy $length bytes from $in_fh to $out_fh. It starts	368	Tries to copy $length bytes from $in_fh to $out_fh. It starts
309	reading at byte offset $in_offset, and starts writing at the current	369	reading at byte offset $in_offset, and starts writing at the current
310	file offset of $out_fh. Because of that, it is not safe to issue	370	file offset of $out_fh. Because of that, it is not safe to issue
311	more than one "aio_sendfile" per $out_fh, as they will interfere	371	more than one "aio_sendfile" per $out_fh, as they will interfere
312	with each other.	372	with each other. The same $in_fh works fine though, as this function
		373	does not move or use the file offset of $in_fh.
313		374
		375	Please note that "aio_sendfile" can read more bytes from $in_fh than
		376	are written, and there is no way to find out how many more bytes
		377	have been read from "aio_sendfile" alone, as "aio_sendfile" only
		378	provides the number of bytes written to $out_fh. Only if the result
		379	value equals $length one can assume that $length bytes have been
		380	read.
		381
		382	Unlike with other "aio_" functions, it makes a lot of sense to use
		383	"aio_sendfile" on non-blocking sockets, as long as one end
		384	(typically the $in_fh) is a file - the file I/O will then be
		385	asynchronous, while the socket I/O will be non-blocking. Note,
		386	however, that you can run into a trap where "aio_sendfile" reads
		387	some data with readahead, then fails to write all data, and when the
		388	socket is ready the next time, the data in the cache is already
		389	lost, forcing "aio_sendfile" to again hit the disk. Explicit
		390	"aio_read" + "aio_write" let's you better control resource usage.
		391
314	This call tries to make use of a native "sendfile" syscall to	392	This call tries to make use of a native "sendfile"-like syscall to
315	provide zero-copy operation. For this to work, $out_fh should refer	393	provide zero-copy operation. For this to work, $out_fh should refer
316	to a socket, and $in_fh should refer to mmap'able file.	394	to a socket, and $in_fh should refer to an mmap'able file.
317		395
318	If the native sendfile call fails or is not implemented, it will be	396	If a native sendfile cannot be found or it fails with "ENOSYS",
319	emulated, so you can call "aio_sendfile" on any type of filehandle	397	"EINVAL", "ENOTSUP", "EOPNOTSUPP", "EAFNOSUPPORT", "EPROTOTYPE" or
320	regardless of the limitations of the operating system.	398	"ENOTSOCK", it will be emulated, so you can call "aio_sendfile" on
		399	any type of filehandle regardless of the limitations of the
		400	operating system.
321		401
322	Please note, however, that "aio_sendfile" can read more bytes from	402	As native sendfile syscalls (as practically any non-POSIX interface
323	$in_fh than are written, and there is no way to find out how many	403	hacked together in a hurry to improve benchmark numbers) tend to be
324	bytes have been read from "aio_sendfile" alone, as "aio_sendfile"	404	rather buggy on many systems, this implementation tries to work
325	only provides the number of bytes written to $out_fh. Only if the	405	around some known bugs in Linux and FreeBSD kernels (probably
326	result value equals $length one can assume that $length bytes have	406	others, too), but that might fail, so you really really should check
327	been read.	407	the return value of "aio_sendfile" - fewre bytes than expected might
		408	have been transferred.
328		409
329	aio_readahead $fh,$offset,$length, $callback->($retval)	410	aio_readahead $fh,$offset,$length, $callback->($retval)
330	"aio_readahead" populates the page cache with data from a file so	411	"aio_readahead" populates the page cache with data from a file so
331	that subsequent reads from that file will not block on disk I/O. The	412	that subsequent reads from that file will not block on disk I/O. The
332	$offset argument specifies the starting point from which data is to	413	$offset argument specifies the starting point from which data is to
…		…
353	Currently, the stats are always 64-bit-stats, i.e. instead of	434	Currently, the stats are always 64-bit-stats, i.e. instead of
354	returning an error when stat'ing a large file, the results will be	435	returning an error when stat'ing a large file, the results will be
355	silently truncated unless perl itself is compiled with large file	436	silently truncated unless perl itself is compiled with large file
356	support.	437	support.
357		438
		439	To help interpret the mode and dev/rdev stat values, IO::AIO offers
		440	the following constants and functions (if not implemented, the
		441	constants will be 0 and the functions will either "croak" or fall
		442	back on traditional behaviour).
		443
		444	"S_IFMT", "S_IFIFO", "S_IFCHR", "S_IFBLK", "S_IFLNK", "S_IFREG",
		445	"S_IFDIR", "S_IFWHT", "S_IFSOCK", "IO::AIO::major $dev_t",
		446	"IO::AIO::minor $dev_t", "IO::AIO::makedev $major, $minor".
		447
358	Example: Print the length of /etc/passwd:	448	Example: Print the length of /etc/passwd:
359		449
360	aio_stat "/etc/passwd", sub {	450	aio_stat "/etc/passwd", sub {
361	$_[0] and die "stat failed: $!";	451	$_[0] and die "stat failed: $!";
362	print "size is ", -s _, "\n";	452	print "size is ", -s _, "\n";
363	};	453	};
364		454
		455	aio_statvfs $fh_or_path, $callback->($statvfs)
		456	Works like the POSIX "statvfs" or "fstatvfs" syscalls, depending on
		457	whether a file handle or path was passed.
		458
		459	On success, the callback is passed a hash reference with the
		460	following members: "bsize", "frsize", "blocks", "bfree", "bavail",
		461	"files", "ffree", "favail", "fsid", "flag" and "namemax". On
		462	failure, "undef" is passed.
		463
		464	The following POSIX IO::AIO::ST_* constants are defined: "ST_RDONLY"
		465	and "ST_NOSUID".
		466
		467	The following non-POSIX IO::AIO::ST_* flag masks are defined to
		468	their correct value when available, or to 0 on systems that do not
		469	support them: "ST_NODEV", "ST_NOEXEC", "ST_SYNCHRONOUS",
		470	"ST_MANDLOCK", "ST_WRITE", "ST_APPEND", "ST_IMMUTABLE",
		471	"ST_NOATIME", "ST_NODIRATIME" and "ST_RELATIME".
		472
		473	Example: stat "/wd" and dump out the data if successful.
		474
		475	aio_statvfs "/wd", sub {
		476	my $f = $_[0]
		477	or die "statvfs: $!";
		478
		479	use Data::Dumper;
		480	say Dumper $f;
		481	};
		482
		483	# result:
		484	{
		485	bsize => 1024,
		486	bfree => 4333064312,
		487	blocks => 10253828096,
		488	files => 2050765568,
		489	flag => 4096,
		490	favail => 2042092649,
		491	bavail => 4333064312,
		492	ffree => 2042092649,
		493	namemax => 255,
		494	frsize => 1024,
		495	fsid => 1810
		496	}
		497
365	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)	498	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
366	Works like perl's "utime" function (including the special case of	499	Works like perl's "utime" function (including the special case of
367	$atime and $mtime being undef). Fractional times are supported if	500	$atime and $mtime being undef). Fractional times are supported if
368	the underlying syscalls support them.	501	the underlying syscalls support them.
369		502
…		…
407		540
408	The only (POSIX-) portable way of calling this function is:	541	The only (POSIX-) portable way of calling this function is:
409		542
410	aio_mknod $path, IO::AIO::S_IFIFO \| $mode, 0, sub { ...	543	aio_mknod $path, IO::AIO::S_IFIFO \| $mode, 0, sub { ...
411		544
		545	See "aio_stat" for info about some potentially helpful extra
		546	constants and functions.
		547
412	aio_link $srcpath, $dstpath, $callback->($status)	548	aio_link $srcpath, $dstpath, $callback->($status)
413	Asynchronously create a new link to the existing object at $srcpath	549	Asynchronously create a new link to the existing object at $srcpath
414	at the path $dstpath and call the callback with the result code.	550	at the path $dstpath and call the callback with the result code.
415		551
416	aio_symlink $srcpath, $dstpath, $callback->($status)	552	aio_symlink $srcpath, $dstpath, $callback->($status)
…		…
439	aio_readdir $pathname, $callback->($entries)	575	aio_readdir $pathname, $callback->($entries)
440	Unlike the POSIX call of the same name, "aio_readdir" reads an	576	Unlike the POSIX call of the same name, "aio_readdir" reads an
441	entire directory (i.e. opendir + readdir + closedir). The entries	577	entire directory (i.e. opendir + readdir + closedir). The entries
442	will not be sorted, and will NOT include the "." and ".." entries.	578	will not be sorted, and will NOT include the "." and ".." entries.
443		579
444	The callback a single argument which is either "undef" or an	580	The callback is passed a single argument which is either "undef" or
445	array-ref with the filenames.	581	an array-ref with the filenames.
		582
		583	aio_readdirx $pathname, $flags, $callback->($entries, $flags)
		584	Quite similar to "aio_readdir", but the $flags argument allows to
		585	tune behaviour and output format. In case of an error, $entries will
		586	be "undef".
		587
		588	The flags are a combination of the following constants, ORed
		589	together (the flags will also be passed to the callback, possibly
		590	modified):
		591
		592	IO::AIO::READDIR_DENTS
		593	When this flag is off, then the callback gets an arrayref
		594	consisting of names only (as with "aio_readdir"), otherwise it
		595	gets an arrayref with "[$name, $type, $inode]" arrayrefs, each
		596	describing a single directory entry in more detail.
		597
		598	$name is the name of the entry.
		599
		600	$type is one of the "IO::AIO::DT_xxx" constants:
		601
		602	"IO::AIO::DT_UNKNOWN", "IO::AIO::DT_FIFO", "IO::AIO::DT_CHR",
		603	"IO::AIO::DT_DIR", "IO::AIO::DT_BLK", "IO::AIO::DT_REG",
		604	"IO::AIO::DT_LNK", "IO::AIO::DT_SOCK", "IO::AIO::DT_WHT".
		605
		606	"IO::AIO::DT_UNKNOWN" means just that: readdir does not know. If
		607	you need to know, you have to run stat yourself. Also, for speed
		608	reasons, the $type scalars are read-only: you can not modify
		609	them.
		610
		611	$inode is the inode number (which might not be exact on systems
		612	with 64 bit inode numbers and 32 bit perls). This field has
		613	unspecified content on systems that do not deliver the inode
		614	information.
		615
		616	IO::AIO::READDIR_DIRS_FIRST
		617	When this flag is set, then the names will be returned in an
		618	order where likely directories come first, in optimal stat
		619	order. This is useful when you need to quickly find directories,
		620	or you want to find all directories while avoiding to stat()
		621	each entry.
		622
		623	If the system returns type information in readdir, then this is
		624	used to find directories directly. Otherwise, likely directories
		625	are names beginning with ".", or otherwise names with no dots,
		626	of which names with short names are tried first.
		627
		628	IO::AIO::READDIR_STAT_ORDER
		629	When this flag is set, then the names will be returned in an
		630	order suitable for stat()'ing each one. That is, when you plan
		631	to stat() all files in the given directory, then the returned
		632	order will likely be fastest.
		633
		634	If both this flag and "IO::AIO::READDIR_DIRS_FIRST" are
		635	specified, then the likely dirs come first, resulting in a less
		636	optimal stat order.
		637
		638	IO::AIO::READDIR_FOUND_UNKNOWN
		639	This flag should not be set when calling "aio_readdirx".
		640	Instead, it is being set by "aio_readdirx", when any of the
		641	$type's found were "IO::AIO::DT_UNKNOWN". The absense of this
		642	flag therefore indicates that all $type's are known, which can
		643	be used to speed up some algorithms.
446		644
447	aio_load $path, $data, $callback->($status)	645	aio_load $path, $data, $callback->($status)
448	This is a composite request that tries to fully load the given file	646	This is a composite request that tries to fully load the given file
449	into memory. Status is the same as with aio_read.	647	into memory. Status is the same as with aio_read.
450		648
451	aio_copy $srcpath, $dstpath, $callback->($status)	649	aio_copy $srcpath, $dstpath, $callback->($status)
452	Try to copy the file (directories not supported as either source	650	Try to copy the file (directories not supported as either source
453	or destination) from $srcpath to $dstpath and call the callback with	651	or destination) from $srcpath to $dstpath and call the callback with
454	the 0 (error) or -1 ok.	652	a status of 0 (ok) or -1 (error, see $!).
455		653
456	This is a composite request that creates the destination file with	654	This is a composite request that creates the destination file with
457	mode 0200 and copies the contents of the source file into it using	655	mode 0200 and copies the contents of the source file into it using
458	"aio_sendfile", followed by restoring atime, mtime, access mode and	656	"aio_sendfile", followed by restoring atime, mtime, access mode and
459	uid/gid, in that order.	657	uid/gid, in that order.
…		…
463	uid/gid, where errors are being ignored.	661	uid/gid, where errors are being ignored.
464		662
465	aio_move $srcpath, $dstpath, $callback->($status)	663	aio_move $srcpath, $dstpath, $callback->($status)
466	Try to move the file (directories not supported as either source	664	Try to move the file (directories not supported as either source
467	or destination) from $srcpath to $dstpath and call the callback with	665	or destination) from $srcpath to $dstpath and call the callback with
468	the 0 (error) or -1 ok.	666	a status of 0 (ok) or -1 (error, see $!).
469		667
470	This is a composite request that tries to rename(2) the file first;	668	This is a composite request that tries to rename(2) the file first;
471	if rename fails with "EXDEV", it copies the file with "aio_copy"	669	if rename fails with "EXDEV", it copies the file with "aio_copy"
472	and, if that is successful, unlinks the $srcpath.	670	and, if that is successful, unlinks the $srcpath.
473		671
…		…
497	Implementation notes.	695	Implementation notes.
498		696
499	The "aio_readdir" cannot be avoided, but "stat()"'ing every entry	697	The "aio_readdir" cannot be avoided, but "stat()"'ing every entry
500	can.	698	can.
501		699
		700	If readdir returns file type information, then this is used directly
		701	to find directories.
		702
502	After reading the directory, the modification time, size etc. of the	703	Otherwise, after reading the directory, the modification time, size
503	directory before and after the readdir is checked, and if they match	704	etc. of the directory before and after the readdir is checked, and
504	(and isn't the current time), the link count will be used to decide	705	if they match (and isn't the current time), the link count will be
505	how many entries are directories (if >= 2). Otherwise, no knowledge	706	used to decide how many entries are directories (if >= 2).
506	of the number of subdirectories will be assumed.	707	Otherwise, no knowledge of the number of subdirectories will be
		708	assumed.
507		709
508	Then entries will be sorted into likely directories (everything	710	Then entries will be sorted into likely directories a non-initial
509	without a non-initial dot currently) and likely non-directories	711	dot currently) and likely non-directories (see "aio_readdirx"). Then
510	(everything else). Then every entry plus an appended "/." will be	712	every entry plus an appended "/." will be "stat"'ed, likely
511	"stat"'ed, likely directories first. If that succeeds, it assumes	713	directories first, in order of their inode numbers. If that
512	that the entry is a directory or a symlink to directory (which will	714	succeeds, it assumes that the entry is a directory or a symlink to
513	be checked seperately). This is often faster than stat'ing the entry	715	directory (which will be checked seperately). This is often faster
514	itself because filesystems might detect the type of the entry	716	than stat'ing the entry itself because filesystems might detect the
515	without reading the inode data (e.g. ext2fs filetype feature).	717	type of the entry without reading the inode data (e.g. ext2fs
		718	filetype feature), even on systems that cannot return the filetype
		719	information on readdir.
516		720
517	If the known number of directories (link count - 2) has been	721	If the known number of directories (link count - 2) has been
518	reached, the rest of the entries is assumed to be non-directories.	722	reached, the rest of the entries is assumed to be non-directories.
519		723
520	This only works with certainty on POSIX (= UNIX) filesystems, which	724	This only works with certainty on POSIX (= UNIX) filesystems, which
…		…
562	operations (E.g. rename). This might not work on all operating	766	operations (E.g. rename). This might not work on all operating
563	systems or have any specific effect, but usually it makes sure that	767	systems or have any specific effect, but usually it makes sure that
564	directory changes get written to disc. It works for anything that	768	directory changes get written to disc. It works for anything that
565	can be opened for read-only, not just directories.	769	can be opened for read-only, not just directories.
566		770
		771	Future versions of this function might fall back to other methods
		772	when "fsync" on the directory fails (such as calling "sync").
		773
567	Passes 0 when everything went ok, and -1 on error.	774	Passes 0 when everything went ok, and -1 on error.
		775
		776	aio_msync $scalar, $offset = 0, $length = undef, flags = 0,
		777	$callback->($status)
		778	This is a rather advanced IO::AIO call, which only works on
		779	mmap(2)ed scalars (see the "IO::AIO::mmap" function, although it
		780	also works on data scalars managed by the Sys::Mmap or Mmap modules,
		781	note that the scalar must only be modified in-place while an aio
		782	operation is pending on it).
		783
		784	It calls the "msync" function of your OS, if available, with the
		785	memory area starting at $offset in the string and ending $length
		786	bytes later. If $length is negative, counts from the end, and if
		787	$length is "undef", then it goes till the end of the string. The
		788	flags can be a combination of "IO::AIO::MS_ASYNC",
		789	"IO::AIO::MS_INVALIDATE" and "IO::AIO::MS_SYNC".
		790
		791	aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0,
		792	$callback->($status)
		793	This is a rather advanced IO::AIO call, which works best on
		794	mmap(2)ed scalars.
		795
		796	It touches (reads or writes) all memory pages in the specified range
		797	inside the scalar. All caveats and parameters are the same as for
		798	"aio_msync", above, except for flags, which must be either 0 (which
		799	reads all pages and ensures they are instantiated) or
		800	"IO::AIO::MT_MODIFY", which modifies the memory page s(by reading
		801	and writing an octet from it, which dirties the page).
		802
		803	aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
		804	This is a rather advanced IO::AIO call, which works best on
		805	mmap(2)ed scalars.
		806
		807	It reads in all the pages of the underlying storage into memory (if
		808	any) and locks them, so they are not getting swapped/paged out or
		809	removed.
		810
		811	If $length is undefined, then the scalar will be locked till the
		812	end.
		813
		814	On systems that do not implement "mlock", this function returns -1
		815	and sets errno to "ENOSYS".
		816
		817	Note that the corresponding "munlock" is synchronous and is
		818	documented under "MISCELLANEOUS FUNCTIONS".
		819
		820	Example: open a file, mmap and mlock it - both will be undone when
		821	$data gets destroyed.
		822
		823	open my $fh, "<", $path or die "$path: $!";
		824	my $data;
		825	IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;
		826	aio_mlock $data; # mlock in background
		827
		828	aio_mlockall $flags, $callback->($status)
		829	Calls the "mlockall" function with the given $flags (a combination
		830	of "IO::AIO::MCL_CURRENT" and "IO::AIO::MCL_FUTURE").
		831
		832	On systems that do not implement "mlockall", this function returns
		833	-1 and sets errno to "ENOSYS".
		834
		835	Note that the corresponding "munlockall" is synchronous and is
		836	documented under "MISCELLANEOUS FUNCTIONS".
		837
		838	Example: asynchronously lock all current and future pages into
		839	memory.
		840
		841	aio_mlockall IO::AIO::MCL_FUTURE;
568		842
569	aio_group $callback->(...)	843	aio_group $callback->(...)
570	This is a very special aio request: Instead of doing something, it	844	This is a very special aio request: Instead of doing something, it
571	is a container for other aio requests, which is useful if you want	845	is a container for other aio requests, which is useful if you want
572	to bundle many requests into a single, composite, request with a	846	to bundle many requests into a single, composite, request with a
…		…
615		889
616	cancel $req	890	cancel $req
617	Cancels the request, if possible. Has the effect of skipping	891	Cancels the request, if possible. Has the effect of skipping
618	execution when entering the execute state and skipping calling the	892	execution when entering the execute state and skipping calling the
619	callback when entering the the result state, but will leave the	893	callback when entering the the result state, but will leave the
620	request otherwise untouched. That means that requests that currently	894	request otherwise untouched (with the exception of readdir). That
621	execute will not be stopped and resources held by the request will	895	means that requests that currently execute will not be stopped and
622	not be freed prematurely.	896	resources held by the request will not be freed prematurely.
623		897
624	cb $req $callback->(...)	898	cb $req $callback->(...)
625	Replace (or simply set) the callback registered to the request.	899	Replace (or simply set) the callback registered to the request.
626		900
627	IO::AIO::GRP CLASS	901	IO::AIO::GRP CLASS
…		…
688		962
689	$grp->cancel_subs	963	$grp->cancel_subs
690	Cancel all subrequests and clears any feeder, but not the group	964	Cancel all subrequests and clears any feeder, but not the group
691	request itself. Useful when you queued a lot of events but got a	965	request itself. Useful when you queued a lot of events but got a
692	result early.	966	result early.
		967
		968	The group request will finish normally (you cannot add requests to
		969	the group).
693		970
694	$grp->result (...)	971	$grp->result (...)
695	Set the result value(s) that will be passed to the group callback	972	Set the result value(s) that will be passed to the group callback
696	when all subrequests have finished and set the groups errno to the	973	when all subrequests have finished and set the groups errno to the
697	current value of errno (just like calling "errno" without an error	974	current value of errno (just like calling "errno" without an error
…		…
757	SUPPORT FUNCTIONS	1034	SUPPORT FUNCTIONS
758	EVENT PROCESSING AND EVENT LOOP INTEGRATION	1035	EVENT PROCESSING AND EVENT LOOP INTEGRATION
759	$fileno = IO::AIO::poll_fileno	1036	$fileno = IO::AIO::poll_fileno
760	Return the request result pipe file descriptor. This filehandle	1037	Return the request result pipe file descriptor. This filehandle
761	must be polled for reading by some mechanism outside this module	1038	must be polled for reading by some mechanism outside this module
762	(e.g. Event or select, see below or the SYNOPSIS). If the pipe	1039	(e.g. EV, Glib, select and so on, see below or the SYNOPSIS). If the
763	becomes readable you have to call "poll_cb" to check the results.	1040	pipe becomes readable you have to call "poll_cb" to check the
		1041	results.
764		1042
765	See "poll_cb" for an example.	1043	See "poll_cb" for an example.
766		1044
767	IO::AIO::poll_cb	1045	IO::AIO::poll_cb
768	Process some outstanding events on the result pipe. You have to call	1046	Process some outstanding events on the result pipe. You have to call
769	this regularly. Returns 0 if all events could be processed, or -1 if	1047	this regularly. Returns 0 if all events could be processed (or there
770	it returned earlier for whatever reason. Returns immediately when no	1048	were no events to process), or -1 if it returned earlier for
771	events are outstanding. The amount of events processed depends on	1049	whatever reason. Returns immediately when no events are outstanding.
772	the settings of "IO::AIO::max_poll_req" and	1050	The amount of events processed depends on the settings of
773	"IO::AIO::max_poll_time".	1051	"IO::AIO::max_poll_req" and "IO::AIO::max_poll_time".
774		1052
775	If not all requests were processed for whatever reason, the	1053	If not all requests were processed for whatever reason, the
776	filehandle will still be ready when "poll_cb" returns, so normally	1054	filehandle will still be ready when "poll_cb" returns, so normally
777	you don't have to do anything special to have it called later.	1055	you don't have to do anything special to have it called later.
778		1056
		1057	Apart from calling "IO::AIO::poll_cb" when the event filehandle
		1058	becomes ready, it can be beneficial to call this function from loops
		1059	which submit a lot of requests, to make sure the results get
		1060	processed when they become available and not just when the loop is
		1061	finished and the event loop takes over again. This function returns
		1062	very fast when there are no outstanding requests.
		1063
779	Example: Install an Event watcher that automatically calls	1064	Example: Install an Event watcher that automatically calls
780	IO::AIO::poll_cb with high priority:	1065	IO::AIO::poll_cb with high priority (more examples can be found in
		1066	the SYNOPSIS section, at the top of this document):
781		1067
782	Event->io (fd => IO::AIO::poll_fileno,	1068	Event->io (fd => IO::AIO::poll_fileno,
783	poll => 'r', async => 1,	1069	poll => 'r', async => 1,
784	cb => \&IO::AIO::poll_cb);	1070	cb => \&IO::AIO::poll_cb);
		1071
		1072	IO::AIO::poll_wait
		1073	If there are any outstanding requests and none of them in the result
		1074	phase, wait till the result filehandle becomes ready for reading
		1075	(simply does a "select" on the filehandle. This is useful if you
		1076	want to synchronously wait for some requests to finish).
		1077
		1078	See "nreqs" for an example.
		1079
		1080	IO::AIO::poll
		1081	Waits until some requests have been handled.
		1082
		1083	Returns the number of requests processed, but is otherwise strictly
		1084	equivalent to:
		1085
		1086	IO::AIO::poll_wait, IO::AIO::poll_cb
		1087
		1088	IO::AIO::flush
		1089	Wait till all outstanding AIO requests have been handled.
		1090
		1091	Strictly equivalent to:
		1092
		1093	IO::AIO::poll_wait, IO::AIO::poll_cb
		1094	while IO::AIO::nreqs;
785		1095
786	IO::AIO::max_poll_reqs $nreqs	1096	IO::AIO::max_poll_reqs $nreqs
787	IO::AIO::max_poll_time $seconds	1097	IO::AIO::max_poll_time $seconds
788	These set the maximum number of requests (default 0, meaning	1098	These set the maximum number of requests (default 0, meaning
789	infinity) that are being processed by "IO::AIO::poll_cb" in one	1099	infinity) that are being processed by "IO::AIO::poll_cb" in one
…		…
813	# use a low priority so other tasks have priority	1123	# use a low priority so other tasks have priority
814	Event->io (fd => IO::AIO::poll_fileno,	1124	Event->io (fd => IO::AIO::poll_fileno,
815	poll => 'r', nice => 1,	1125	poll => 'r', nice => 1,
816	cb => &IO::AIO::poll_cb);	1126	cb => &IO::AIO::poll_cb);
817		1127
818	IO::AIO::poll_wait
819	If there are any outstanding requests and none of them in the result
820	phase, wait till the result filehandle becomes ready for reading
821	(simply does a "select" on the filehandle. This is useful if you
822	want to synchronously wait for some requests to finish).
823
824	See "nreqs" for an example.
825
826	IO::AIO::poll
827	Waits until some requests have been handled.
828
829	Returns the number of requests processed, but is otherwise strictly
830	equivalent to:
831
832	IO::AIO::poll_wait, IO::AIO::poll_cb
833
834	IO::AIO::flush
835	Wait till all outstanding AIO requests have been handled.
836
837	Strictly equivalent to:
838
839	IO::AIO::poll_wait, IO::AIO::poll_cb
840	while IO::AIO::nreqs;
841
842	CONTROLLING THE NUMBER OF THREADS	1128	CONTROLLING THE NUMBER OF THREADS
843	IO::AIO::min_parallel $nthreads	1129	IO::AIO::min_parallel $nthreads
844	Set the minimum number of AIO threads to $nthreads. The current	1130	Set the minimum number of AIO threads to $nthreads. The current
845	default is 8, which means eight asynchronous operations can execute	1131	default is 8, which means eight asynchronous operations can execute
846	concurrently at any one time (the number of outstanding requests,	1132	concurrently at any one time (the number of outstanding requests,
…		…
875		1161
876	Under normal circumstances you don't need to call this function.	1162	Under normal circumstances you don't need to call this function.
877		1163
878	IO::AIO::max_idle $nthreads	1164	IO::AIO::max_idle $nthreads
879	Limit the number of threads (default: 4) that are allowed to idle	1165	Limit the number of threads (default: 4) that are allowed to idle
880	(i.e., threads that did not get a request to process within 10	1166	(i.e., threads that did not get a request to process within the idle
881	seconds). That means if a thread becomes idle while $nthreads other	1167	timeout (default: 10 seconds). That means if a thread becomes idle
882	threads are also idle, it will free its resources and exit.	1168	while $nthreads other threads are also idle, it will free its
		1169	resources and exit.
883		1170
884	This is useful when you allow a large number of threads (e.g. 100 or	1171	This is useful when you allow a large number of threads (e.g. 100 or
885	1000) to allow for extremely high load situations, but want to free	1172	1000) to allow for extremely high load situations, but want to free
886	resources under normal circumstances (1000 threads can easily	1173	resources under normal circumstances (1000 threads can easily
887	consume 30MB of RAM).	1174	consume 30MB of RAM).
888		1175
889	The default is probably ok in most situations, especially if thread	1176	The default is probably ok in most situations, especially if thread
890	creation is fast. If thread creation is very slow on your system you	1177	creation is fast. If thread creation is very slow on your system you
891	might want to use larger values.	1178	might want to use larger values.
892		1179
		1180	IO::AIO::idle_timeout $seconds
		1181	Sets the minimum idle timeout (default 10) after which worker
		1182	threads are allowed to exit. SEe "IO::AIO::max_idle".
		1183
893	IO::AIO::max_outstanding $maxreqs	1184	IO::AIO::max_outstanding $maxreqs
		1185	Sets the maximum number of outstanding requests to $nreqs. If you do
		1186	queue up more than this number of requests, the next call to
		1187	"IO::AIO::poll_cb" (and other functions calling "poll_cb", such as
		1188	"IO::AIO::flush" or "IO::AIO::poll") will block until the limit is
		1189	no longer exceeded.
		1190
		1191	In other words, this setting does not enforce a queue limit, but can
		1192	be used to make poll functions block if the limit is exceeded.
		1193
894	This is a very bad function to use in interactive programs because	1194	This is a very bad function to use in interactive programs because
895	it blocks, and a bad way to reduce concurrency because it is	1195	it blocks, and a bad way to reduce concurrency because it is
896	inexact: Better use an "aio_group" together with a feed callback.	1196	inexact: Better use an "aio_group" together with a feed callback.
897		1197
898	Sets the maximum number of outstanding requests to $nreqs. If you do	1198	It's main use is in scripts without an event loop - when you want to
899	queue up more than this number of requests, the next call to the	1199	stat a lot of files, you can write somehting like this:
900	"poll_cb" (and "poll_some" and other functions calling "poll_cb")
901	function will block until the limit is no longer exceeded.
902		1200
903	The default value is very large, so there is no practical limit on	1201	IO::AIO::max_outstanding 32;
		1202
		1203	for my $path (...) {
		1204	aio_stat $path , ...;
		1205	IO::AIO::poll_cb;
		1206	}
		1207
		1208	IO::AIO::flush;
		1209
		1210	The call to "poll_cb" inside the loop will normally return
		1211	instantly, but as soon as more thna 32 reqeusts are in-flight, it
		1212	will block until some requests have been handled. This keeps the
		1213	loop from pushing a large number of "aio_stat" requests onto the
		1214	queue.
		1215
		1216	The default value for "max_outstanding" is very large, so there is
904	the number of outstanding requests.	1217	no practical limit on the number of outstanding requests.
905
906	You can still queue as many requests as you want. Therefore,
907	"max_outstanding" is mainly useful in simple scripts (with low
908	values) or as a stop gap to shield against fatal memory overflow
909	(with large values).
910		1218
911	STATISTICAL INFORMATION	1219	STATISTICAL INFORMATION
912	IO::AIO::nreqs	1220	IO::AIO::nreqs
913	Returns the number of requests currently in the ready, execute or	1221	Returns the number of requests currently in the ready, execute or
914	pending states (i.e. for which their callback has not been invoked	1222	pending states (i.e. for which their callback has not been invoked
…		…
925		1233
926	IO::AIO::npending	1234	IO::AIO::npending
927	Returns the number of requests currently in the pending state	1235	Returns the number of requests currently in the pending state
928	(executed, but not yet processed by poll_cb).	1236	(executed, but not yet processed by poll_cb).
929		1237
		1238	MISCELLANEOUS FUNCTIONS
		1239	IO::AIO implements some functions that might be useful, but are not
		1240	asynchronous.
		1241
		1242	IO::AIO::sendfile $ofh, $ifh, $offset, $count
		1243	Calls the "eio_sendfile_sync" function, which is like
		1244	"aio_sendfile", but is blocking (this makes most sense if you know
		1245	the input data is likely cached already and the output filehandle is
		1246	set to non-blocking operations).
		1247
		1248	Returns the number of bytes copied, or -1 on error.
		1249
		1250	IO::AIO::fadvise $fh, $offset, $len, $advice
		1251	Simply calls the "posix_fadvise" function (see its manpage for
		1252	details). The following advice constants are avaiable:
		1253	"IO::AIO::FADV_NORMAL", "IO::AIO::FADV_SEQUENTIAL",
		1254	"IO::AIO::FADV_RANDOM", "IO::AIO::FADV_NOREUSE",
		1255	"IO::AIO::FADV_WILLNEED", "IO::AIO::FADV_DONTNEED".
		1256
		1257	On systems that do not implement "posix_fadvise", this function
		1258	returns ENOSYS, otherwise the return value of "posix_fadvise".
		1259
		1260	IO::AIO::madvise $scalar, $offset, $len, $advice
		1261	Simply calls the "posix_madvise" function (see its manpage for
		1262	details). The following advice constants are avaiable:
		1263	"IO::AIO::MADV_NORMAL", "IO::AIO::MADV_SEQUENTIAL",
		1264	"IO::AIO::MADV_RANDOM", "IO::AIO::MADV_WILLNEED",
		1265	"IO::AIO::MADV_DONTNEED".
		1266
		1267	On systems that do not implement "posix_madvise", this function
		1268	returns ENOSYS, otherwise the return value of "posix_madvise".
		1269
		1270	IO::AIO::mprotect $scalar, $offset, $len, $protect
		1271	Simply calls the "mprotect" function on the preferably AIO::mmap'ed
		1272	$scalar (see its manpage for details). The following protect
		1273	constants are avaiable: "IO::AIO::PROT_NONE", "IO::AIO::PROT_READ",
		1274	"IO::AIO::PROT_WRITE", "IO::AIO::PROT_EXEC".
		1275
		1276	On systems that do not implement "mprotect", this function returns
		1277	ENOSYS, otherwise the return value of "mprotect".
		1278
		1279	IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
		1280	Memory-maps a file (or anonymous memory range) and attaches it to
		1281	the given $scalar, which will act like a string scalar.
		1282
		1283	The only operations allowed on the scalar are "substr"/"vec" that
		1284	don't change the string length, and most read-only operations such
		1285	as copying it or searching it with regexes and so on.
		1286
		1287	Anything else is unsafe and will, at best, result in memory leaks.
		1288
		1289	The memory map associated with the $scalar is automatically removed
		1290	when the $scalar is destroyed, or when the "IO::AIO::mmap" or
		1291	"IO::AIO::munmap" functions are called.
		1292
		1293	This calls the "mmap"(2) function internally. See your system's
		1294	manual page for details on the $length, $prot and $flags parameters.
		1295
		1296	The $length must be larger than zero and smaller than the actual
		1297	filesize.
		1298
		1299	$prot is a combination of "IO::AIO::PROT_NONE",
		1300	"IO::AIO::PROT_EXEC", "IO::AIO::PROT_READ" and/or
		1301	"IO::AIO::PROT_WRITE",
		1302
		1303	$flags can be a combination of "IO::AIO::MAP_SHARED" or
		1304	"IO::AIO::MAP_PRIVATE", or a number of system-specific flags (when
		1305	not available, the are defined as 0): "IO::AIO::MAP_ANONYMOUS"
		1306	(which is set to "MAP_ANON" if your system only provides this
		1307	constant), "IO::AIO::MAP_HUGETLB", "IO::AIO::MAP_LOCKED",
		1308	"IO::AIO::MAP_NORESERVE", "IO::AIO::MAP_POPULATE" or
		1309	"IO::AIO::MAP_NONBLOCK"
		1310
		1311	If $fh is "undef", then a file descriptor of -1 is passed.
		1312
		1313	$offset is the offset from the start of the file - it generally must
		1314	be a multiple of "IO::AIO::PAGESIZE" and defaults to 0.
		1315
		1316	Example:
		1317
		1318	use Digest::MD5;
		1319	use IO::AIO;
		1320
		1321	open my $fh, "<verybigfile"
		1322	or die "$!";
		1323
		1324	IO::AIO::mmap my $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh
		1325	or die "verybigfile: $!";
		1326
		1327	my $fast_md5 = md5 $data;
		1328
		1329	IO::AIO::munmap $scalar
		1330	Removes a previous mmap and undefines the $scalar.
		1331
		1332	IO::AIO::munlock $scalar, $offset = 0, $length = undef
		1333	Calls the "munlock" function, undoing the effects of a previous
		1334	"aio_mlock" call (see its description for details).
		1335
		1336	IO::AIO::munlockall
		1337	Calls the "munlockall" function.
		1338
		1339	On systems that do not implement "munlockall", this function returns
		1340	ENOSYS, otherwise the return value of "munlockall".
		1341
		1342	EVENT LOOP INTEGRATION
		1343	It is recommended to use AnyEvent::AIO to integrate IO::AIO
		1344	automatically into many event loops:
		1345
		1346	# AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...)
		1347	use AnyEvent::AIO;
		1348
		1349	You can also integrate IO::AIO manually into many event loops, here are
		1350	some examples of how to do this:
		1351
		1352	# EV integration
		1353	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
		1354
		1355	# Event integration
		1356	Event->io (fd => IO::AIO::poll_fileno,
		1357	poll => 'r',
		1358	cb => \&IO::AIO::poll_cb);
		1359
		1360	# Glib/Gtk2 integration
		1361	add_watch Glib::IO IO::AIO::poll_fileno,
		1362	in => sub { IO::AIO::poll_cb; 1 };
		1363
		1364	# Tk integration
		1365	Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
		1366	readable => \&IO::AIO::poll_cb);
		1367
		1368	# Danga::Socket integration
		1369	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
		1370	\&IO::AIO::poll_cb);
		1371
930	FORK BEHAVIOUR	1372	FORK BEHAVIOUR
931	This module should do "the right thing" when the process using it forks:	1373	Usage of pthreads in a program changes the semantics of fork
		1374	considerably. Specifically, only async-safe functions can be called
		1375	after fork. Perl doesn't know about this, so in general, you cannot call
		1376	fork with defined behaviour in perl. IO::AIO uses pthreads, so this
		1377	applies, but many other extensions and (for inexplicable reasons) perl
		1378	itself often is linked against pthreads, so this limitation applies.
932		1379
933	Before the fork, IO::AIO enters a quiescent state where no requests can	1380	Some operating systems have extensions that allow safe use of fork, and
934	be added in other threads and no results will be processed. After the	1381	this module should do "the right thing" on those, and tries on others.
935	fork the parent simply leaves the quiescent state and continues	1382	At the time of this writing (2011) only GNU/Linux supports these
936	request/result processing, while the child frees the request/result	1383	extensions to POSIX.
937	queue (so that the requests started before the fork will only be handled
938	in the parent). Threads will be started on demand until the limit set in
939	the parent process has been reached again.
940
941	In short: the parent will, after a short pause, continue as if fork had
942	not been called, while the child will act as if IO::AIO has not been
943	used yet.
944		1384
945	MEMORY USAGE	1385	MEMORY USAGE
946	Per-request usage:	1386	Per-request usage:
947		1387
948	Each aio request uses - depending on your architecture - around 100-200	1388	Each aio request uses - depending on your architecture - around 100-200

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Comparing IO-AIO/README (file contents): Revision 1.34 by root, Thu Nov 20 09:01:40 2008 UTC vs. Revision 1.48 by root, Wed Jun 29 11:25:17 2011 UTC

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Comparing IO-AIO/README (file contents):
Revision 1.34 by root, Thu Nov 20 09:01:40 2008 UTC vs.
Revision 1.48 by root, Wed Jun 29 11:25:17 2011 UTC