[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 1.45 by root, Thu Dec 30 07:19:31 2010 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::max_outstanding $maxreqs
		210	IO::AIO::nreqs
		211	IO::AIO::nready
		212	IO::AIO::npending
		213
		214	IO::AIO::sendfile $ofh, $ifh, $offset, $count
		215	IO::AIO::fadvise $fh, $offset, $len, $advice
		216	IO::AIO::madvise $scalar, $offset, $length, $advice
		217	IO::AIO::mprotect $scalar, $offset, $length, $protect
		218	IO::AIO::munlock $scalar, $offset = 0, $length = undef
		219	IO::AIO::munlockall
		220
174	AIO REQUEST FUNCTIONS	221	AIO REQUEST FUNCTIONS
175	All the "aio_*" calls are more or less thin wrappers around the syscall	222	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	223	with the same name (sans "aio_"). The arguments are similar or
177	identical, and they all accept an additional (and optional) $callback	224	identical, and they all accept an additional (and optional) $callback
178	argument which must be a code reference. This code reference will get	225	argument which must be a code reference. This code reference will get
…		…
249	will be modified by the umask in effect then the request is being	296	will be modified by the umask in effect then the request is being
250	executed, so better never change the umask.	297	executed, so better never change the umask.
251		298
252	Example:	299	Example:
253		300
254	aio_open "/etc/passwd", O_RDONLY, 0, sub {	301	aio_open "/etc/passwd", IO::AIO::O_RDONLY, 0, sub {
255	if ($_[0]) {	302	if ($_[0]) {
256	print "open successful, fh is $_[0]\n";	303	print "open successful, fh is $_[0]\n";
257	...	304	...
258	} else {	305	} else {
259	die "open failed: $!\n";	306	die "open failed: $!\n";
…		…
275	Or in other words: the file descriptor will be closed, but it will	322	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.	323	not be free for reuse until the perl filehandle is closed.
277		324
278	aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	325	aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
279	aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)	326	aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
280	Reads or writes $length bytes from the specified $fh and $offset	327	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	328	$offset into the scalar given by $data and offset $dataoffset and
282	callback without the actual number of bytes read (or -1 on error,	329	calls the callback without the actual number of bytes read (or -1 on
283	just like the syscall).	330	error, just like the syscall).
		331
		332	"aio_read" will, like "sysread", shrink or grow the $data scalar to
		333	offset plus the actual number of bytes read.
284		334
285	If $offset is undefined, then the current file descriptor offset	335	If $offset is undefined, then the current file descriptor offset
286	will be used (and updated), otherwise the file descriptor offset	336	will be used (and updated), otherwise the file descriptor offset
287	will not be changed by these calls.	337	will not be changed by these calls.
288		338
…		…
309	reading at byte offset $in_offset, and starts writing at the current	359	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	360	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	361	more than one "aio_sendfile" per $out_fh, as they will interfere
312	with each other.	362	with each other.
313		363
		364	Please note that "aio_sendfile" can read more bytes from $in_fh than
		365	are written, and there is no way to find out how many bytes have
		366	been read from "aio_sendfile" alone, as "aio_sendfile" only provides
		367	the number of bytes written to $out_fh. Only if the result value
		368	equals $length one can assume that $length bytes have been read.
		369
		370	Unlike with other "aio_" functions, it makes a lot of sense to use
		371	"aio_sendfile" on non-blocking sockets, as long as one end
		372	(typically the $in_fh) is a file - the file I/O will then be
		373	asynchronous, while the socket I/O will be non-blocking. Note,
		374	however, that you can run into a trap where "aio_sendfile" reads
		375	some data with readahead, then fails to write all data, and when the
		376	socket is ready the next time, the data in the cache is already
		377	lost, forcing "aio_sendfile" to again hit the disk. Explicit
		378	"aio_read" + "aio_write" let's you control resource usage much
		379	better.
		380
314	This call tries to make use of a native "sendfile" syscall to	381	This call tries to make use of a native "sendfile" syscall to
315	provide zero-copy operation. For this to work, $out_fh should refer	382	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.	383	to a socket, and $in_fh should refer to an mmap'able file.
317		384
318	If the native sendfile call fails or is not implemented, it will be	385	If a native sendfile cannot be found or it fails with "ENOSYS",
		386	"ENOTSUP", "EOPNOTSUPP", "EAFNOSUPPORT", "EPROTOTYPE" or "ENOTSOCK",
319	emulated, so you can call "aio_sendfile" on any type of filehandle	387	it will be emulated, so you can call "aio_sendfile" on any type of
320	regardless of the limitations of the operating system.	388	filehandle regardless of the limitations of the operating system.
321
322	Please note, however, that "aio_sendfile" can read more bytes from
323	$in_fh than are written, and there is no way to find out how many
324	bytes have been read from "aio_sendfile" alone, as "aio_sendfile"
325	only provides the number of bytes written to $out_fh. Only if the
326	result value equals $length one can assume that $length bytes have
327	been read.
328		389
329	aio_readahead $fh,$offset,$length, $callback->($retval)	390	aio_readahead $fh,$offset,$length, $callback->($retval)
330	"aio_readahead" populates the page cache with data from a file so	391	"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	392	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	393	$offset argument specifies the starting point from which data is to
…		…
360	aio_stat "/etc/passwd", sub {	421	aio_stat "/etc/passwd", sub {
361	$_[0] and die "stat failed: $!";	422	$_[0] and die "stat failed: $!";
362	print "size is ", -s _, "\n";	423	print "size is ", -s _, "\n";
363	};	424	};
364		425
		426	aio_statvfs $fh_or_path, $callback->($statvfs)
		427	Works like the POSIX "statvfs" or "fstatvfs" syscalls, depending on
		428	whether a file handle or path was passed.
		429
		430	On success, the callback is passed a hash reference with the
		431	following members: "bsize", "frsize", "blocks", "bfree", "bavail",
		432	"files", "ffree", "favail", "fsid", "flag" and "namemax". On
		433	failure, "undef" is passed.
		434
		435	The following POSIX IO::AIO::ST_* constants are defined: "ST_RDONLY"
		436	and "ST_NOSUID".
		437
		438	The following non-POSIX IO::AIO::ST_* flag masks are defined to
		439	their correct value when available, or to 0 on systems that do not
		440	support them: "ST_NODEV", "ST_NOEXEC", "ST_SYNCHRONOUS",
		441	"ST_MANDLOCK", "ST_WRITE", "ST_APPEND", "ST_IMMUTABLE",
		442	"ST_NOATIME", "ST_NODIRATIME" and "ST_RELATIME".
		443
		444	Example: stat "/wd" and dump out the data if successful.
		445
		446	aio_statvfs "/wd", sub {
		447	my $f = $_[0]
		448	or die "statvfs: $!";
		449
		450	use Data::Dumper;
		451	say Dumper $f;
		452	};
		453
		454	# result:
		455	{
		456	bsize => 1024,
		457	bfree => 4333064312,
		458	blocks => 10253828096,
		459	files => 2050765568,
		460	flag => 4096,
		461	favail => 2042092649,
		462	bavail => 4333064312,
		463	ffree => 2042092649,
		464	namemax => 255,
		465	frsize => 1024,
		466	fsid => 1810
		467	}
		468
365	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)	469	aio_utime $fh_or_path, $atime, $mtime, $callback->($status)
366	Works like perl's "utime" function (including the special case of	470	Works like perl's "utime" function (including the special case of
367	$atime and $mtime being undef). Fractional times are supported if	471	$atime and $mtime being undef). Fractional times are supported if
368	the underlying syscalls support them.	472	the underlying syscalls support them.
369		473
…		…
439	aio_readdir $pathname, $callback->($entries)	543	aio_readdir $pathname, $callback->($entries)
440	Unlike the POSIX call of the same name, "aio_readdir" reads an	544	Unlike the POSIX call of the same name, "aio_readdir" reads an
441	entire directory (i.e. opendir + readdir + closedir). The entries	545	entire directory (i.e. opendir + readdir + closedir). The entries
442	will not be sorted, and will NOT include the "." and ".." entries.	546	will not be sorted, and will NOT include the "." and ".." entries.
443		547
444	The callback a single argument which is either "undef" or an	548	The callback is passed a single argument which is either "undef" or
445	array-ref with the filenames.	549	an array-ref with the filenames.
		550
		551	aio_readdirx $pathname, $flags, $callback->($entries, $flags)
		552	Quite similar to "aio_readdir", but the $flags argument allows to
		553	tune behaviour and output format. In case of an error, $entries will
		554	be "undef".
		555
		556	The flags are a combination of the following constants, ORed
		557	together (the flags will also be passed to the callback, possibly
		558	modified):
		559
		560	IO::AIO::READDIR_DENTS
		561	When this flag is off, then the callback gets an arrayref with
		562	of names only (as with "aio_readdir"), otherwise it gets an
		563	arrayref with "[$name, $type, $inode]" arrayrefs, each
		564	describing a single directory entry in more detail.
		565
		566	$name is the name of the entry.
		567
		568	$type is one of the "IO::AIO::DT_xxx" constants:
		569
		570	"IO::AIO::DT_UNKNOWN", "IO::AIO::DT_FIFO", "IO::AIO::DT_CHR",
		571	"IO::AIO::DT_DIR", "IO::AIO::DT_BLK", "IO::AIO::DT_REG",
		572	"IO::AIO::DT_LNK", "IO::AIO::DT_SOCK", "IO::AIO::DT_WHT".
		573
		574	"IO::AIO::DT_UNKNOWN" means just that: readdir does not know. If
		575	you need to know, you have to run stat yourself. Also, for speed
		576	reasons, the $type scalars are read-only: you can not modify
		577	them.
		578
		579	$inode is the inode number (which might not be exact on systems
		580	with 64 bit inode numbers and 32 bit perls). This field has
		581	unspecified content on systems that do not deliver the inode
		582	information.
		583
		584	IO::AIO::READDIR_DIRS_FIRST
		585	When this flag is set, then the names will be returned in an
		586	order where likely directories come first. This is useful when
		587	you need to quickly find directories, or you want to find all
		588	directories while avoiding to stat() each entry.
		589
		590	If the system returns type information in readdir, then this is
		591	used to find directories directly. Otherwise, likely directories
		592	are files beginning with ".", or otherwise files with no dots,
		593	of which files with short names are tried first.
		594
		595	IO::AIO::READDIR_STAT_ORDER
		596	When this flag is set, then the names will be returned in an
		597	order suitable for stat()'ing each one. That is, when you plan
		598	to stat() all files in the given directory, then the returned
		599	order will likely be fastest.
		600
		601	If both this flag and "IO::AIO::READDIR_DIRS_FIRST" are
		602	specified, then the likely dirs come first, resulting in a less
		603	optimal stat order.
		604
		605	IO::AIO::READDIR_FOUND_UNKNOWN
		606	This flag should not be set when calling "aio_readdirx".
		607	Instead, it is being set by "aio_readdirx", when any of the
		608	$type's found were "IO::AIO::DT_UNKNOWN". The absense of this
		609	flag therefore indicates that all $type's are known, which can
		610	be used to speed up some algorithms.
446		611
447	aio_load $path, $data, $callback->($status)	612	aio_load $path, $data, $callback->($status)
448	This is a composite request that tries to fully load the given file	613	This is a composite request that tries to fully load the given file
449	into memory. Status is the same as with aio_read.	614	into memory. Status is the same as with aio_read.
450		615
451	aio_copy $srcpath, $dstpath, $callback->($status)	616	aio_copy $srcpath, $dstpath, $callback->($status)
452	Try to copy the file (directories not supported as either source	617	Try to copy the file (directories not supported as either source
453	or destination) from $srcpath to $dstpath and call the callback with	618	or destination) from $srcpath to $dstpath and call the callback with
454	the 0 (error) or -1 ok.	619	a status of 0 (ok) or -1 (error, see $!).
455		620
456	This is a composite request that creates the destination file with	621	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	622	mode 0200 and copies the contents of the source file into it using
458	"aio_sendfile", followed by restoring atime, mtime, access mode and	623	"aio_sendfile", followed by restoring atime, mtime, access mode and
459	uid/gid, in that order.	624	uid/gid, in that order.
…		…
463	uid/gid, where errors are being ignored.	628	uid/gid, where errors are being ignored.
464		629
465	aio_move $srcpath, $dstpath, $callback->($status)	630	aio_move $srcpath, $dstpath, $callback->($status)
466	Try to move the file (directories not supported as either source	631	Try to move the file (directories not supported as either source
467	or destination) from $srcpath to $dstpath and call the callback with	632	or destination) from $srcpath to $dstpath and call the callback with
468	the 0 (error) or -1 ok.	633	a status of 0 (ok) or -1 (error, see $!).
469		634
470	This is a composite request that tries to rename(2) the file first;	635	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"	636	if rename fails with "EXDEV", it copies the file with "aio_copy"
472	and, if that is successful, unlinks the $srcpath.	637	and, if that is successful, unlinks the $srcpath.
473		638
…		…
497	Implementation notes.	662	Implementation notes.
498		663
499	The "aio_readdir" cannot be avoided, but "stat()"'ing every entry	664	The "aio_readdir" cannot be avoided, but "stat()"'ing every entry
500	can.	665	can.
501		666
		667	If readdir returns file type information, then this is used directly
		668	to find directories.
		669
502	After reading the directory, the modification time, size etc. of the	670	Otherwise, after reading the directory, the modification time, size
503	directory before and after the readdir is checked, and if they match	671	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	672	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	673	used to decide how many entries are directories (if >= 2).
506	of the number of subdirectories will be assumed.	674	Otherwise, no knowledge of the number of subdirectories will be
		675	assumed.
507		676
508	Then entries will be sorted into likely directories (everything	677	Then entries will be sorted into likely directories a non-initial
509	without a non-initial dot currently) and likely non-directories	678	dot currently) and likely non-directories (see "aio_readdirx"). Then
510	(everything else). Then every entry plus an appended "/." will be	679	every entry plus an appended "/." will be "stat"'ed, likely
511	"stat"'ed, likely directories first. If that succeeds, it assumes	680	directories first, in order of their inode numbers. If that
512	that the entry is a directory or a symlink to directory (which will	681	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	682	directory (which will be checked seperately). This is often faster
514	itself because filesystems might detect the type of the entry	683	than stat'ing the entry itself because filesystems might detect the
515	without reading the inode data (e.g. ext2fs filetype feature).	684	type of the entry without reading the inode data (e.g. ext2fs
		685	filetype feature), even on systems that cannot return the filetype
		686	information on readdir.
516		687
517	If the known number of directories (link count - 2) has been	688	If the known number of directories (link count - 2) has been
518	reached, the rest of the entries is assumed to be non-directories.	689	reached, the rest of the entries is assumed to be non-directories.
519		690
520	This only works with certainty on POSIX (= UNIX) filesystems, which	691	This only works with certainty on POSIX (= UNIX) filesystems, which
…		…
562	operations (E.g. rename). This might not work on all operating	733	operations (E.g. rename). This might not work on all operating
563	systems or have any specific effect, but usually it makes sure that	734	systems or have any specific effect, but usually it makes sure that
564	directory changes get written to disc. It works for anything that	735	directory changes get written to disc. It works for anything that
565	can be opened for read-only, not just directories.	736	can be opened for read-only, not just directories.
566		737
		738	Future versions of this function might fall back to other methods
		739	when "fsync" on the directory fails (such as calling "sync").
		740
567	Passes 0 when everything went ok, and -1 on error.	741	Passes 0 when everything went ok, and -1 on error.
		742
		743	aio_msync $scalar, $offset = 0, $length = undef, flags = 0,
		744	$callback->($status)
		745	This is a rather advanced IO::AIO call, which only works on
		746	mmap(2)ed scalars (see the "IO::AIO::mmap" function, although it
		747	also works on data scalars managed by the Sys::Mmap or Mmap modules,
		748	note that the scalar must only be modified in-place while an aio
		749	operation is pending on it).
		750
		751	It calls the "msync" function of your OS, if available, with the
		752	memory area starting at $offset in the string and ending $length
		753	bytes later. If $length is negative, counts from the end, and if
		754	$length is "undef", then it goes till the end of the string. The
		755	flags can be a combination of "IO::AIO::MS_ASYNC",
		756	"IO::AIO::MS_INVALIDATE" and "IO::AIO::MS_SYNC".
		757
		758	aio_mtouch $scalar, $offset = 0, $length = undef, flags = 0,
		759	$callback->($status)
		760	This is a rather advanced IO::AIO call, which works best on
		761	mmap(2)ed scalars.
		762
		763	It touches (reads or writes) all memory pages in the specified range
		764	inside the scalar. All caveats and parameters are the same as for
		765	"aio_msync", above, except for flags, which must be either 0 (which
		766	reads all pages and ensures they are instantiated) or
		767	"IO::AIO::MT_MODIFY", which modifies the memory page s(by reading
		768	and writing an octet from it, which dirties the page).
		769
		770	aio_mlock $scalar, $offset = 0, $length = undef, $callback->($status)
		771	This is a rather advanced IO::AIO call, which works best on
		772	mmap(2)ed scalars.
		773
		774	It reads in all the pages of the underlying storage into memory (if
		775	any) and locks them, so they are not getting swapped/paged out or
		776	removed.
		777
		778	If $length is undefined, then the scalar will be locked till the
		779	end.
		780
		781	On systems that do not implement "mlock", this function returns -1
		782	and sets errno to "ENOSYS".
		783
		784	Note that the corresponding "munlock" is synchronous and is
		785	documented under "MISCELLANEOUS FUNCTIONS".
		786
		787	Example: open a file, mmap and mlock it - both will be undone when
		788	$data gets destroyed.
		789
		790	open my $fh, "<", $path or die "$path: $!";
		791	my $data;
		792	IO::AIO::mmap $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh;
		793	aio_mlock $data; # mlock in background
		794
		795	aio_mlockall $flags, $callback->($status)
		796	Calls the "mlockall" function with the given $flags (a combination
		797	of "IO::AIO::MCL_CURRENT" and "IO::AIO::MCL_FUTURE").
		798
		799	On systems that do not implement "mlockall", this function returns
		800	-1 and sets errno to "ENOSYS".
		801
		802	Note that the corresponding "munlockall" is synchronous and is
		803	documented under "MISCELLANEOUS FUNCTIONS".
		804
		805	Example: asynchronously lock all current and future pages into
		806	memory.
		807
		808	aio_mlockall IO::AIO::MCL_FUTURE;
568		809
569	aio_group $callback->(...)	810	aio_group $callback->(...)
570	This is a very special aio request: Instead of doing something, it	811	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	812	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	813	to bundle many requests into a single, composite, request with a
…		…
615		856
616	cancel $req	857	cancel $req
617	Cancels the request, if possible. Has the effect of skipping	858	Cancels the request, if possible. Has the effect of skipping
618	execution when entering the execute state and skipping calling the	859	execution when entering the execute state and skipping calling the
619	callback when entering the the result state, but will leave the	860	callback when entering the the result state, but will leave the
620	request otherwise untouched. That means that requests that currently	861	request otherwise untouched (with the exception of readdir). That
621	execute will not be stopped and resources held by the request will	862	means that requests that currently execute will not be stopped and
622	not be freed prematurely.	863	resources held by the request will not be freed prematurely.
623		864
624	cb $req $callback->(...)	865	cb $req $callback->(...)
625	Replace (or simply set) the callback registered to the request.	866	Replace (or simply set) the callback registered to the request.
626		867
627	IO::AIO::GRP CLASS	868	IO::AIO::GRP CLASS
…		…
688		929
689	$grp->cancel_subs	930	$grp->cancel_subs
690	Cancel all subrequests and clears any feeder, but not the group	931	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	932	request itself. Useful when you queued a lot of events but got a
692	result early.	933	result early.
		934
		935	The group request will finish normally (you cannot add requests to
		936	the group).
693		937
694	$grp->result (...)	938	$grp->result (...)
695	Set the result value(s) that will be passed to the group callback	939	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	940	when all subrequests have finished and set the groups errno to the
697	current value of errno (just like calling "errno" without an error	941	current value of errno (just like calling "errno" without an error
…		…
757	SUPPORT FUNCTIONS	1001	SUPPORT FUNCTIONS
758	EVENT PROCESSING AND EVENT LOOP INTEGRATION	1002	EVENT PROCESSING AND EVENT LOOP INTEGRATION
759	$fileno = IO::AIO::poll_fileno	1003	$fileno = IO::AIO::poll_fileno
760	Return the request result pipe file descriptor. This filehandle	1004	Return the request result pipe file descriptor. This filehandle
761	must be polled for reading by some mechanism outside this module	1005	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	1006	(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.	1007	pipe becomes readable you have to call "poll_cb" to check the
		1008	results.
764		1009
765	See "poll_cb" for an example.	1010	See "poll_cb" for an example.
766		1011
767	IO::AIO::poll_cb	1012	IO::AIO::poll_cb
768	Process some outstanding events on the result pipe. You have to call	1013	Process some outstanding events on the result pipe. You have to call
…		…
775	If not all requests were processed for whatever reason, the	1020	If not all requests were processed for whatever reason, the
776	filehandle will still be ready when "poll_cb" returns, so normally	1021	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.	1022	you don't have to do anything special to have it called later.
778		1023
779	Example: Install an Event watcher that automatically calls	1024	Example: Install an Event watcher that automatically calls
780	IO::AIO::poll_cb with high priority:	1025	IO::AIO::poll_cb with high priority (more examples can be found in
		1026	the SYNOPSIS section, at the top of this document):
781		1027
782	Event->io (fd => IO::AIO::poll_fileno,	1028	Event->io (fd => IO::AIO::poll_fileno,
783	poll => 'r', async => 1,	1029	poll => 'r', async => 1,
784	cb => \&IO::AIO::poll_cb);	1030	cb => \&IO::AIO::poll_cb);
		1031
		1032	IO::AIO::poll_wait
		1033	If there are any outstanding requests and none of them in the result
		1034	phase, wait till the result filehandle becomes ready for reading
		1035	(simply does a "select" on the filehandle. This is useful if you
		1036	want to synchronously wait for some requests to finish).
		1037
		1038	See "nreqs" for an example.
		1039
		1040	IO::AIO::poll
		1041	Waits until some requests have been handled.
		1042
		1043	Returns the number of requests processed, but is otherwise strictly
		1044	equivalent to:
		1045
		1046	IO::AIO::poll_wait, IO::AIO::poll_cb
		1047
		1048	IO::AIO::flush
		1049	Wait till all outstanding AIO requests have been handled.
		1050
		1051	Strictly equivalent to:
		1052
		1053	IO::AIO::poll_wait, IO::AIO::poll_cb
		1054	while IO::AIO::nreqs;
785		1055
786	IO::AIO::max_poll_reqs $nreqs	1056	IO::AIO::max_poll_reqs $nreqs
787	IO::AIO::max_poll_time $seconds	1057	IO::AIO::max_poll_time $seconds
788	These set the maximum number of requests (default 0, meaning	1058	These set the maximum number of requests (default 0, meaning
789	infinity) that are being processed by "IO::AIO::poll_cb" in one	1059	infinity) that are being processed by "IO::AIO::poll_cb" in one
…		…
813	# use a low priority so other tasks have priority	1083	# use a low priority so other tasks have priority
814	Event->io (fd => IO::AIO::poll_fileno,	1084	Event->io (fd => IO::AIO::poll_fileno,
815	poll => 'r', nice => 1,	1085	poll => 'r', nice => 1,
816	cb => &IO::AIO::poll_cb);	1086	cb => &IO::AIO::poll_cb);
817		1087
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	1088	CONTROLLING THE NUMBER OF THREADS
843	IO::AIO::min_parallel $nthreads	1089	IO::AIO::min_parallel $nthreads
844	Set the minimum number of AIO threads to $nthreads. The current	1090	Set the minimum number of AIO threads to $nthreads. The current
845	default is 8, which means eight asynchronous operations can execute	1091	default is 8, which means eight asynchronous operations can execute
846	concurrently at any one time (the number of outstanding requests,	1092	concurrently at any one time (the number of outstanding requests,
…		…
924	executed).	1170	executed).
925		1171
926	IO::AIO::npending	1172	IO::AIO::npending
927	Returns the number of requests currently in the pending state	1173	Returns the number of requests currently in the pending state
928	(executed, but not yet processed by poll_cb).	1174	(executed, but not yet processed by poll_cb).
		1175
		1176	MISCELLANEOUS FUNCTIONS
		1177	IO::AIO implements some functions that might be useful, but are not
		1178	asynchronous.
		1179
		1180	IO::AIO::sendfile $ofh, $ifh, $offset, $count
		1181	Calls the "eio_sendfile_sync" function, which is like
		1182	"aio_sendfile", but is blocking (this makes most sense if you know
		1183	the input data is likely cached already and the output filehandle is
		1184	set to non-blocking operations).
		1185
		1186	Returns the number of bytes copied, or -1 on error.
		1187
		1188	IO::AIO::fadvise $fh, $offset, $len, $advice
		1189	Simply calls the "posix_fadvise" function (see its manpage for
		1190	details). The following advice constants are avaiable:
		1191	"IO::AIO::FADV_NORMAL", "IO::AIO::FADV_SEQUENTIAL",
		1192	"IO::AIO::FADV_RANDOM", "IO::AIO::FADV_NOREUSE",
		1193	"IO::AIO::FADV_WILLNEED", "IO::AIO::FADV_DONTNEED".
		1194
		1195	On systems that do not implement "posix_fadvise", this function
		1196	returns ENOSYS, otherwise the return value of "posix_fadvise".
		1197
		1198	IO::AIO::madvise $scalar, $offset, $len, $advice
		1199	Simply calls the "posix_madvise" function (see its manpage for
		1200	details). The following advice constants are avaiable:
		1201	"IO::AIO::MADV_NORMAL", "IO::AIO::MADV_SEQUENTIAL",
		1202	"IO::AIO::MADV_RANDOM", "IO::AIO::MADV_WILLNEED",
		1203	"IO::AIO::MADV_DONTNEED".
		1204
		1205	On systems that do not implement "posix_madvise", this function
		1206	returns ENOSYS, otherwise the return value of "posix_madvise".
		1207
		1208	IO::AIO::mprotect $scalar, $offset, $len, $protect
		1209	Simply calls the "mprotect" function on the preferably AIO::mmap'ed
		1210	$scalar (see its manpage for details). The following protect
		1211	constants are avaiable: "IO::AIO::PROT_NONE", "IO::AIO::PROT_READ",
		1212	"IO::AIO::PROT_WRITE", "IO::AIO::PROT_EXEC".
		1213
		1214	On systems that do not implement "mprotect", this function returns
		1215	ENOSYS, otherwise the return value of "mprotect".
		1216
		1217	IO::AIO::mmap $scalar, $length, $prot, $flags, $fh[, $offset]
		1218	Memory-maps a file (or anonymous memory range) and attaches it to
		1219	the given $scalar, which will act like a string scalar.
		1220
		1221	The only operations allowed on the scalar are "substr"/"vec" that
		1222	don't change the string length, and most read-only operations such
		1223	as copying it or searching it with regexes and so on.
		1224
		1225	Anything else is unsafe and will, at best, result in memory leaks.
		1226
		1227	The memory map associated with the $scalar is automatically removed
		1228	when the $scalar is destroyed, or when the "IO::AIO::mmap" or
		1229	"IO::AIO::munmap" functions are called.
		1230
		1231	This calls the "mmap"(2) function internally. See your system's
		1232	manual page for details on the $length, $prot and $flags parameters.
		1233
		1234	The $length must be larger than zero and smaller than the actual
		1235	filesize.
		1236
		1237	$prot is a combination of "IO::AIO::PROT_NONE",
		1238	"IO::AIO::PROT_EXEC", "IO::AIO::PROT_READ" and/or
		1239	"IO::AIO::PROT_WRITE",
		1240
		1241	$flags can be a combination of "IO::AIO::MAP_SHARED" or
		1242	"IO::AIO::MAP_PRIVATE", or a number of system-specific flags (when
		1243	not available, the are defined as 0): "IO::AIO::MAP_ANONYMOUS"
		1244	(which is set to "MAP_ANON" if your system only provides this
		1245	constant), "IO::AIO::MAP_HUGETLB", "IO::AIO::MAP_LOCKED",
		1246	"IO::AIO::MAP_NORESERVE", "IO::AIO::MAP_POPULATE" or
		1247	"IO::AIO::MAP_NONBLOCK"
		1248
		1249	If $fh is "undef", then a file descriptor of -1 is passed.
		1250
		1251	$offset is the offset from the start of the file - it generally must
		1252	be a multiple of "IO::AIO::PAGESIZE" and defaults to 0.
		1253
		1254	Example:
		1255
		1256	use Digest::MD5;
		1257	use IO::AIO;
		1258
		1259	open my $fh, "<verybigfile"
		1260	or die "$!";
		1261
		1262	IO::AIO::mmap my $data, -s $fh, IO::AIO::PROT_READ, IO::AIO::MAP_SHARED, $fh
		1263	or die "verybigfile: $!";
		1264
		1265	my $fast_md5 = md5 $data;
		1266
		1267	IO::AIO::munmap $scalar
		1268	Removes a previous mmap and undefines the $scalar.
		1269
		1270	IO::AIO::munlock $scalar, $offset = 0, $length = undef
		1271	Calls the "munlock" function, undoing the effects of a previous
		1272	"aio_mlock" call (see its description for details).
		1273
		1274	IO::AIO::munlockall
		1275	Calls the "munlockall" function.
		1276
		1277	On systems that do not implement "munlockall", this function returns
		1278	ENOSYS, otherwise the return value of "munlockall".
		1279
		1280	EVENT LOOP INTEGRATION
		1281	It is recommended to use AnyEvent::AIO to integrate IO::AIO
		1282	automatically into many event loops:
		1283
		1284	# AnyEvent integration (EV, Event, Glib, Tk, POE, urxvt, pureperl...)
		1285	use AnyEvent::AIO;
		1286
		1287	You can also integrate IO::AIO manually into many event loops, here are
		1288	some examples of how to do this:
		1289
		1290	# EV integration
		1291	my $aio_w = EV::io IO::AIO::poll_fileno, EV::READ, \&IO::AIO::poll_cb;
		1292
		1293	# Event integration
		1294	Event->io (fd => IO::AIO::poll_fileno,
		1295	poll => 'r',
		1296	cb => \&IO::AIO::poll_cb);
		1297
		1298	# Glib/Gtk2 integration
		1299	add_watch Glib::IO IO::AIO::poll_fileno,
		1300	in => sub { IO::AIO::poll_cb; 1 };
		1301
		1302	# Tk integration
		1303	Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
		1304	readable => \&IO::AIO::poll_cb);
		1305
		1306	# Danga::Socket integration
		1307	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
		1308	\&IO::AIO::poll_cb);
929		1309
930	FORK BEHAVIOUR	1310	FORK BEHAVIOUR
931	This module should do "the right thing" when the process using it forks:	1311	This module should do "the right thing" when the process using it forks:
932		1312
933	Before the fork, IO::AIO enters a quiescent state where no requests can	1313	Before the fork, IO::AIO enters a quiescent state where no requests can

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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 1.45 by root, Thu Dec 30 07:19:31 2010 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 1.45 by root, Thu Dec 30 07:19:31 2010 UTC