[ViewVC] Diff of: cvs/IO-AIO/AIO.pm

Comparing IO-AIO/AIO.pm (file contents):
Revision 1.3 by root, Sun Jul 10 20:07:11 2005 UTC vs.
Revision 1.70 by root, Tue Oct 24 03:40:38 2006 UTC

…		…
3	IO::AIO - Asynchronous Input/Output	3	IO::AIO - Asynchronous Input/Output
4		4
5	=head1 SYNOPSIS	5	=head1 SYNOPSIS
6		6
7	use IO::AIO;	7	use IO::AIO;
		8
		9	aio_open "/etc/passwd", O_RDONLY, 0, sub {
		10	my ($fh) = @_;
		11	...
		12	};
		13
		14	aio_unlink "/tmp/file", sub { };
		15
		16	aio_read $fh, 30000, 1024, $buffer, 0, sub {
		17	$_[0] > 0 or die "read error: $!";
		18	};
		19
		20	# version 2+ has request and group objects
		21	use IO::AIO 2;
		22
		23	aioreq_pri 4; # give next request a very high priority
		24	my $req = aio_unlink "/tmp/file", sub { };
		25	$req->cancel; # cancel request if still in queue
		26
		27	my $grp = aio_group sub { print "all stats done\n" };
		28	add $grp aio_stat "..." for ...;
		29
		30	# AnyEvent integration
		31	open my $fh, "<&=" . IO::AIO::poll_fileno or die "$!";
		32	my $w = AnyEvent->io (fh => $fh, poll => 'r', cb => sub { IO::AIO::poll_cb });
		33
		34	# Event integration
		35	Event->io (fd => IO::AIO::poll_fileno,
		36	poll => 'r',
		37	cb => \&IO::AIO::poll_cb);
		38
		39	# Glib/Gtk2 integration
		40	add_watch Glib::IO IO::AIO::poll_fileno,
		41	in => sub { IO::AIO::poll_cb; 1 };
		42
		43	# Tk integration
		44	Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
		45	readable => \&IO::AIO::poll_cb);
		46
		47	# Danga::Socket integration
		48	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
		49	\&IO::AIO::poll_cb);
8		50
9	=head1 DESCRIPTION	51	=head1 DESCRIPTION
10		52
11	This module implements asynchronous I/O using whatever means your	53	This module implements asynchronous I/O using whatever means your
12	operating system supports.	54	operating system supports.
13		55
14	Currently, a number of threads are started that execute your read/writes	56	Currently, a number of threads are started that execute your read/writes
15	and signal their completion. You don't need thread support in your libc or	57	and signal their completion. You don't need thread support in perl, and
16	perl, and the threads created by this module will not be visible to the	58	the threads created by this module will not be visible to perl. In the
17	pthreads library. In the future, this module might make use of the native	59	future, this module might make use of the native aio functions available
18	aio functions available on many operating systems. However, they are often	60	on many operating systems. However, they are often not well-supported
19	not well-supported (Linux doesn't allow them on normal files currently,	61	(Linux doesn't allow them on normal files currently, for example),
20	for example), and they would only support aio_read and aio_write, so the	62	and they would only support aio_read and aio_write, so the remaining
21	remaining functionality would have to be implemented using threads anyway.	63	functionality would have to be implemented using threads anyway.
22		64
23	Although the module will work with in the presence of other threads, it is	65	Although the module will work with in the presence of other threads,
24	currently not reentrant, so use appropriate locking yourself.	66	it is currently not reentrant in any way, so use appropriate locking
		67	yourself, always call C<poll_cb> from within the same thread, or never
		68	call C<poll_cb> (or other C<aio_> functions) recursively.
25		69
26	=head2 API NOTES	70	=cut
		71
		72	package IO::AIO;
		73
		74	no warnings;
		75	use strict 'vars';
		76
		77	use base 'Exporter';
		78
		79	BEGIN {
		80	our $VERSION = '2.0';
		81
		82	our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close aio_stat
		83	aio_lstat aio_unlink aio_rmdir aio_readdir aio_scandir aio_symlink
		84	aio_fsync aio_fdatasync aio_readahead aio_rename aio_link aio_move
		85	aio_group aio_nop);
		86	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
		87	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
		88	min_parallel max_parallel max_outstanding nreqs);
		89
		90	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';
		91
		92	require XSLoader;
		93	XSLoader::load ("IO::AIO", $VERSION);
		94	}
		95
		96	=head1 FUNCTIONS
		97
		98	=head2 AIO FUNCTIONS
27		99
28	All the C<aio_*> calls are more or less thin wrappers around the syscall	100	All the C<aio_*> calls are more or less thin wrappers around the syscall
29	with the same name (sans C<aio_>). The arguments are similar or identical,	101	with the same name (sans C<aio_>). The arguments are similar or identical,
30	and they all accept an additional C<$callback> argument which must be	102	and they all accept an additional (and optional) C<$callback> argument
31	a code reference. This code reference will get called with the syscall	103	which must be a code reference. This code reference will get called with
32	return code (e.g. most syscalls return C<-1> on error, unlike perl, which	104	the syscall return code (e.g. most syscalls return C<-1> on error, unlike
33	usually delivers "false") as it's sole argument when the given syscall has	105	perl, which usually delivers "false") as it's sole argument when the given
34	been executed asynchronously.	106	syscall has been executed asynchronously.
35		107
36	All functions that expect a filehandle will also accept a file descriptor.	108	All functions expecting a filehandle keep a copy of the filehandle
		109	internally until the request has finished.
37		110
		111	All requests return objects of type L<IO::AIO::REQ> that allow further
		112	manipulation of those requests while they are in-flight.
		113
38	The filenames you pass to these routines I<must> be absolute. The reason	114	The pathnames you pass to these routines I<must> be absolute and
39	is that at the time the request is being executed, the current working	115	encoded in byte form. The reason for the former is that at the time the
40	directory could have changed. Alternatively, you can make sure that you	116	request is being executed, the current working directory could have
		117	changed. Alternatively, you can make sure that you never change the
41	never change the current working directory.	118	current working directory.
		119
		120	To encode pathnames to byte form, either make sure you either: a)
		121	always pass in filenames you got from outside (command line, readdir
		122	etc.), b) are ASCII or ISO 8859-1, c) use the Encode module and encode
		123	your pathnames to the locale (or other) encoding in effect in the user
		124	environment, d) use Glib::filename_from_unicode on unicode filenames or e)
		125	use something else.
42		126
43	=over 4	127	=over 4
44		128
45	=cut	129	=item aioreq_pri $pri
46		130
47	package IO::AIO;	131	Sets the priority for the next aio request. The default priority
		132	is C<0>, the minimum and maximum priorities are C<-4> and C<4>,
		133	respectively. Requests with higher priority will be serviced first.
48		134
49	use base 'Exporter';	135	The priority will be reset to C<0> after each call to one of the C<aio_>
		136	functions.
50		137
51	use Fcntl ();	138	Example: open a file with low priority, then read something from it with
		139	higher priority so the read request is serviced before other low priority
		140	open requests (potentially spamming the cache):
52		141
53	BEGIN {	142	aioreq_pri -3;
54	$VERSION = 0.2;	143	aio_open ..., sub {
		144	return unless $_[0];
55		145
56	@EXPORT = qw(aio_read aio_write aio_open aio_close aio_stat aio_lstat aio_unlink	146	aioreq_pri -2;
57	aio_fsync aio_fdatasync aio_readahead);	147	aio_read $_[0], ..., sub {
58	@EXPORT_OK = qw(poll_fileno poll_cb min_parallel max_parallel nreqs);	148	...
		149	};
		150	};
59		151
60	require XSLoader;	152	=item aioreq_nice $pri_adjust
61	XSLoader::load IO::AIO, $VERSION;
62	}
63		153
64	=item IO::AIO::min_parallel $nthreads	154	Similar to C<aioreq_pri>, but subtracts the given value from the current
		155	priority, so effects are cumulative.
65		156
66	Set the minimum number of AIO threads to C<$nthreads>. The default is
67	C<1>, which means a single asynchronous operation can be done at one time
68	(the number of outstanding operations, however, is unlimited).
69
70	It is recommended to keep the number of threads low, as some linux
71	kernel versions will scale negatively with the number of threads (higher
72	parallelity => MUCH higher latency).
73
74	Under normal circumstances you don't need to call this function, as this
75	module automatically starts a single async thread.
76
77	=item IO::AIO::max_parallel $nthreads
78
79	Sets the maximum number of AIO threads to C<$nthreads>. If more than
80	the specified number of threads are currently running, kill them. This
81	function blocks until the limit is reached.
82
83	This module automatically runs C<max_parallel 0> at program end, to ensure
84	that all threads are killed and that there are no outstanding requests.
85
86	Under normal circumstances you don't need to call this function.
87
88	=item $fileno = IO::AIO::poll_fileno
89
90	Return the I<request result pipe filehandle>. This filehandle must be
91	polled for reading by some mechanism outside this module (e.g. Event
92	or select, see below). If the pipe becomes readable you have to call
93	C<poll_cb> to check the results.
94
95	See C<poll_cb> for an example.
96
97	=item IO::AIO::poll_cb
98
99	Process all outstanding events on the result pipe. You have to call this
100	regularly. Returns the number of events processed. Returns immediately
101	when no events are outstanding.
102
103	You can use Event to multiplex, e.g.:
104
105	Event->io (fd => IO::AIO::poll_fileno,
106	poll => 'r', async => 1,
107	cb => \&IO::AIO::poll_cb);
108
109	=item IO::AIO::poll_wait
110
111	Wait till the result filehandle becomes ready for reading (simply does a
112	select on the filehandle. This is useful if you want to synchronously wait
113	for some requests to finish).
114
115	See C<nreqs> for an example.
116
117	=item IO::AIO::nreqs
118
119	Returns the number of requests currently outstanding.
120
121	Example: wait till there are no outstanding requests anymore:
122
123	IO::AIO::poll_wait, IO::AIO::poll_cb
124	while IO::AIO::nreqs;
125
126	=item aio_open $pathname, $flags, $mode, $callback	157	=item aio_open $pathname, $flags, $mode, $callback->($fh)
127		158
128	Asynchronously open or create a file and call the callback with a newly	159	Asynchronously open or create a file and call the callback with a newly
129	created filehandle for the file.	160	created filehandle for the file.
130		161
131	The pathname passed to C<aio_open> must be absolute. See API NOTES, above,	162	The pathname passed to C<aio_open> must be absolute. See API NOTES, above,
132	for an explanation.	163	for an explanation.
133		164
134	The C<$mode> argument is a bitmask. See the C<Fcntl> module for a	165	The C<$flags> argument is a bitmask. See the C<Fcntl> module for a
135	list. They are the same as used in C<sysopen>.	166	list. They are the same as used by C<sysopen>.
		167
		168	Likewise, C<$mode> specifies the mode of the newly created file, if it
		169	didn't exist and C<O_CREAT> has been given, just like perl's C<sysopen>,
		170	except that it is mandatory (i.e. use C<0> if you don't create new files,
		171	and C<0666> or C<0777> if you do).
136		172
137	Example:	173	Example:
138		174
139	aio_open "/etc/passwd", O_RDONLY, 0, sub {	175	aio_open "/etc/passwd", O_RDONLY, 0, sub {
140	if ($_[0]) {	176	if ($_[0]) {
…		…
143	} else {	179	} else {
144	die "open failed: $!\n";	180	die "open failed: $!\n";
145	}	181	}
146	};	182	};
147		183
148	=item aio_close $fh, $callback	184	=item aio_close $fh, $callback->($status)
149		185
150	Asynchronously close a file and call the callback with the result	186	Asynchronously close a file and call the callback with the result
151	code. I<WARNING:> although accepted, you should not pass in a perl	187	code. I<WARNING:> although accepted, you should not pass in a perl
152	filehandle here, as perl will likely close the file descriptor itself when	188	filehandle here, as perl will likely close the file descriptor another
153	the filehandle is destroyed. Normally, you can safely call perls C<close>	189	time when the filehandle is destroyed. Normally, you can safely call perls
154	or just let filehandles go out of scope.	190	C<close> or just let filehandles go out of scope.
155		191
		192	This is supposed to be a bug in the API, so that might change. It's
		193	therefore best to avoid this function.
		194
156	=item aio_read $fh,$offset,$length, $data,$dataoffset,$callback	195	=item aio_read $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
157		196
158	=item aio_write $fh,$offset,$length, $data,$dataoffset,$callback	197	=item aio_write $fh,$offset,$length, $data,$dataoffset, $callback->($retval)
159		198
160	Reads or writes C<length> bytes from the specified C<fh> and C<offset>	199	Reads or writes C<length> bytes from the specified C<fh> and C<offset>
161	into the scalar given by C<data> and offset C<dataoffset> and calls the	200	into the scalar given by C<data> and offset C<dataoffset> and calls the
162	callback without the actual number of bytes read (or -1 on error, just	201	callback without the actual number of bytes read (or -1 on error, just
163	like the syscall).	202	like the syscall).
164		203
		204	The C<$data> scalar I<MUST NOT> be modified in any way while the request
		205	is outstanding. Modifying it can result in segfaults or WW3 (if the
		206	necessary/optional hardware is installed).
		207
165	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, strating at	208	Example: Read 15 bytes at offset 7 into scalar C<$buffer>, starting at
166	offset C<0> within the scalar:	209	offset C<0> within the scalar:
167		210
168	aio_read $fh, 7, 15, $buffer, 0, sub {	211	aio_read $fh, 7, 15, $buffer, 0, sub {
169	$_[0] >= 0 or die "read error: $!";	212	$_[0] > 0 or die "read error: $!";
170	print "read <$buffer>\n";	213	print "read $_[0] bytes: <$buffer>\n";
171	};	214	};
172		215
		216	=item aio_move $srcpath, $dstpath, $callback->($status)
		217
		218	[EXPERIMENTAL due to internal aio_group use]
		219
		220	Try to move the I<file> (directories not supported as either source or
		221	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		222	the C<0> (error) or C<-1> ok.
		223
		224	This is a composite request that tries to rename(2) the file first. If
		225	rename files with C<EXDEV>, it creates the destination file with mode 0200
		226	and copies the contents of the source file into it using C<aio_sendfile>,
		227	followed by restoring atime, mtime, access mode and uid/gid, in that
		228	order, and unlinking the C<$srcpath>.
		229
		230	If an error occurs, the partial destination file will be unlinked, if
		231	possible, except when setting atime, mtime, access mode and uid/gid, where
		232	errors are being ignored.
		233
		234	=cut
		235
		236	sub aio_move($$$) {
		237	my ($src, $dst, $cb) = @_;
		238
		239	my $grp = aio_group $cb;
		240
		241	add $grp aio_rename $src, $dst, sub {
		242	if ($_[0] && $! == EXDEV) {
		243	add $grp aio_open $src, O_RDONLY, 0, sub {
		244	if (my $src_fh = $_[0]) {
		245	my @stat = stat $src_fh;
		246
		247	add $grp aio_open $dst, O_WRONLY, 0200, sub {
		248	if (my $dst_fh = $_[0]) {
		249	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
		250	close $src_fh;
		251
		252	if ($_[0] == $stat[7]) {
		253	utime $stat[8], $stat[9], $dst;
		254	chmod $stat[2] & 07777, $dst_fh;
		255	chown $stat[4], $stat[5], $dst_fh;
		256	close $dst_fh;
		257
		258	add $grp aio_unlink $src, sub {
		259	$grp->result ($_[0]);
		260	};
		261	} else {
		262	my $errno = $!;
		263	add $grp aio_unlink $dst, sub {
		264	$! = $errno;
		265	$grp->result (-1);
		266	};
		267	}
		268	};
		269	} else {
		270	$grp->result (-1);
		271	}
		272	},
		273
		274	} else {
		275	$grp->result (-1);
		276	}
		277	};
		278	} else {
		279	$grp->result ($_[0]);
		280	}
		281	};
		282
		283	$grp
		284	}
		285
		286	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
		287
		288	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
		289	reading at byte offset C<$in_offset>, and starts writing at the current
		290	file offset of C<$out_fh>. Because of that, it is not safe to issue more
		291	than one C<aio_sendfile> per C<$out_fh>, as they will interfere with each
		292	other.
		293
		294	This call tries to make use of a native C<sendfile> syscall to provide
		295	zero-copy operation. For this to work, C<$out_fh> should refer to a
		296	socket, and C<$in_fh> should refer to mmap'able file.
		297
		298	If the native sendfile call fails or is not implemented, it will be
		299	emulated, so you can call C<aio_sendfile> on any type of filehandle
		300	regardless of the limitations of the operating system.
		301
		302	Please note, however, that C<aio_sendfile> can read more bytes from
		303	C<$in_fh> than are written, and there is no way to find out how many
		304	bytes have been read from C<aio_sendfile> alone, as C<aio_sendfile> only
		305	provides the number of bytes written to C<$out_fh>. Only if the result
		306	value equals C<$length> one can assume that C<$length> bytes have been
		307	read.
		308
173	=item aio_readahead $fh,$offset,$length, $callback	309	=item aio_readahead $fh,$offset,$length, $callback->($retval)
174		310
175	Asynchronously reads the specified byte range into the page cache, using
176	the C<readahead> syscall. If that syscall doesn't exist the status will be
177	C<-1> and C<$!> is set to ENOSYS.
178
179	readahead() populates the page cache with data from a file so that	311	C<aio_readahead> populates the page cache with data from a file so that
180	subsequent reads from that file will not block on disk I/O. The C<$offset>	312	subsequent reads from that file will not block on disk I/O. The C<$offset>
181	argument specifies the starting point from which data is to be read and	313	argument specifies the starting point from which data is to be read and
182	C<$length> specifies the number of bytes to be read. I/O is performed in	314	C<$length> specifies the number of bytes to be read. I/O is performed in
183	whole pages, so that offset is effectively rounded down to a page boundary	315	whole pages, so that offset is effectively rounded down to a page boundary
184	and bytes are read up to the next page boundary greater than or equal to	316	and bytes are read up to the next page boundary greater than or equal to
185	(off-set+length). aio_readahead() does not read beyond the end of the	317	(off-set+length). C<aio_readahead> does not read beyond the end of the
186	file. The current file offset of the file is left unchanged.	318	file. The current file offset of the file is left unchanged.
187		319
		320	If that syscall doesn't exist (likely if your OS isn't Linux) it will be
		321	emulated by simply reading the data, which would have a similar effect.
		322
188	=item aio_stat $fh_or_path, $callback	323	=item aio_stat $fh_or_path, $callback->($status)
189		324
190	=item aio_lstat $fh, $callback	325	=item aio_lstat $fh, $callback->($status)
191		326
192	Works like perl's C<stat> or C<lstat> in void context. The callback will	327	Works like perl's C<stat> or C<lstat> in void context. The callback will
193	be called after the stat and the results will be available using C<stat _>	328	be called after the stat and the results will be available using C<stat _>
194	or C<-s _> etc...	329	or C<-s _> etc...
195		330
…		…
205	aio_stat "/etc/passwd", sub {	340	aio_stat "/etc/passwd", sub {
206	$_[0] and die "stat failed: $!";	341	$_[0] and die "stat failed: $!";
207	print "size is ", -s _, "\n";	342	print "size is ", -s _, "\n";
208	};	343	};
209		344
210	=item aio_unlink $pathname, $callback	345	=item aio_unlink $pathname, $callback->($status)
211		346
212	Asynchronously unlink (delete) a file and call the callback with the	347	Asynchronously unlink (delete) a file and call the callback with the
213	result code.	348	result code.
214		349
		350	=item aio_link $srcpath, $dstpath, $callback->($status)
		351
		352	Asynchronously create a new link to the existing object at C<$srcpath> at
		353	the path C<$dstpath> and call the callback with the result code.
		354
		355	=item aio_symlink $srcpath, $dstpath, $callback->($status)
		356
		357	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at
		358	the path C<$dstpath> and call the callback with the result code.
		359
		360	=item aio_rename $srcpath, $dstpath, $callback->($status)
		361
		362	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
		363	rename(2) and call the callback with the result code.
		364
		365	=item aio_rmdir $pathname, $callback->($status)
		366
		367	Asynchronously rmdir (delete) a directory and call the callback with the
		368	result code.
		369
		370	=item aio_readdir $pathname, $callback->($entries)
		371
		372	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire
		373	directory (i.e. opendir + readdir + closedir). The entries will not be
		374	sorted, and will B<NOT> include the C<.> and C<..> entries.
		375
		376	The callback a single argument which is either C<undef> or an array-ref
		377	with the filenames.
		378
		379	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
		380
		381	[EXPERIMENTAL due to internal aio_group use]
		382
		383	Scans a directory (similar to C<aio_readdir>) but additionally tries to
		384	separate the entries of directory C<$path> into two sets of names, ones
		385	you can recurse into (directories or links to them), and ones you cannot
		386	recurse into (everything else).
		387
		388	C<aio_scandir> is a composite request that creates of many sub requests_
		389	C<$maxreq> specifies the maximum number of outstanding aio requests that
		390	this function generates. If it is C<< <= 0 >>, then a suitable default
		391	will be chosen (currently 6).
		392
		393	On error, the callback is called without arguments, otherwise it receives
		394	two array-refs with path-relative entry names.
		395
		396	Example:
		397
		398	aio_scandir $dir, 0, sub {
		399	my ($dirs, $nondirs) = @_;
		400	print "real directories: @$dirs\n";
		401	print "everything else: @$nondirs\n";
		402	};
		403
		404	Implementation notes.
		405
		406	The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can.
		407
		408	After reading the directory, the modification time, size etc. of the
		409	directory before and after the readdir is checked, and if they match (and
		410	isn't the current time), the link count will be used to decide how many
		411	entries are directories (if >= 2). Otherwise, no knowledge of the number
		412	of subdirectories will be assumed.
		413
		414	Then entries will be sorted into likely directories (everything without
		415	a non-initial dot currently) and likely non-directories (everything
		416	else). Then every entry plus an appended C</.> will be C<stat>'ed,
		417	likely directories first. If that succeeds, it assumes that the entry
		418	is a directory or a symlink to directory (which will be checked
		419	seperately). This is often faster than stat'ing the entry itself because
		420	filesystems might detect the type of the entry without reading the inode
		421	data (e.g. ext2fs filetype feature).
		422
		423	If the known number of directories (link count - 2) has been reached, the
		424	rest of the entries is assumed to be non-directories.
		425
		426	This only works with certainty on POSIX (= UNIX) filesystems, which
		427	fortunately are the vast majority of filesystems around.
		428
		429	It will also likely work on non-POSIX filesystems with reduced efficiency
		430	as those tend to return 0 or 1 as link counts, which disables the
		431	directory counting heuristic.
		432
		433	=cut
		434
		435	sub aio_scandir($$$) {
		436	my ($path, $maxreq, $cb) = @_;
		437
		438	my $grp = aio_group $cb;
		439
		440	$maxreq = 6 if $maxreq <= 0;
		441
		442	# stat once
		443	add $grp aio_stat $path, sub {
		444	return $grp->result () if $_[0];
		445	my $now = time;
		446	my $hash1 = join ":", (stat _)[0,1,3,7,9];
		447
		448	# read the directory entries
		449	add $grp aio_readdir $path, sub {
		450	my $entries = shift
		451	or return $grp->result ();
		452
		453	# stat the dir another time
		454	add $grp aio_stat $path, sub {
		455	my $hash2 = join ":", (stat _)[0,1,3,7,9];
		456
		457	my $ndirs;
		458
		459	# take the slow route if anything looks fishy
		460	if ($hash1 ne $hash2 or (stat _)[9] == $now) {
		461	$ndirs = -1;
		462	} else {
		463	# if nlink == 2, we are finished
		464	# on non-posix-fs's, we rely on nlink < 2
		465	$ndirs = (stat _)[3] - 2
		466	or return $grp->result ([], $entries);
		467	}
		468
		469	# sort into likely dirs and likely nondirs
		470	# dirs == files without ".", short entries first
		471	$entries = [map $_->[0],
		472	sort { $b->[1] cmp $a->[1] }
		473	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
		474	@$entries];
		475
		476	my (@dirs, @nondirs);
		477
		478	my ($statcb, $schedcb);
		479	my $nreq = 0;
		480
		481	my $statgrp = add $grp aio_group;
		482
		483	$schedcb = sub {
		484	if (@$entries) {
		485	if ($nreq < $maxreq) {
		486	my $ent = pop @$entries;
		487	$nreq++;
		488	add $statgrp aio_stat "$path/$ent/.", sub { $statcb->($_[0], $ent) };
		489	}
		490	} elsif (!$nreq) {
		491	# finished
		492	$statgrp->cancel;
		493	undef $statcb;
		494	undef $schedcb;
		495	$grp->result (\@dirs, \@nondirs);
		496	}
		497	};
		498	$statcb = sub {
		499	my ($status, $entry) = @_;
		500
		501	if ($status < 0) {
		502	$nreq--;
		503	push @nondirs, $entry;
		504	&$schedcb;
		505	} else {
		506	# need to check for real directory
		507	add $grp aio_lstat "$path/$entry", sub {
		508	$nreq--;
		509
		510	if (-d _) {
		511	push @dirs, $entry;
		512
		513	if (!--$ndirs) {
		514	push @nondirs, @$entries;
		515	$entries = [];
		516	}
		517	} else {
		518	push @nondirs, $entry;
		519	}
		520
		521	&$schedcb;
		522	}
		523	}
		524	};
		525
		526	&$schedcb while @$entries && $nreq < $maxreq;
		527	};
		528	};
		529	};
		530
		531	$grp
		532	}
		533
215	=item aio_fsync $fh, $callback	534	=item aio_fsync $fh, $callback->($status)
216		535
217	Asynchronously call fsync on the given filehandle and call the callback	536	Asynchronously call fsync on the given filehandle and call the callback
218	with the fsync result code.	537	with the fsync result code.
219		538
220	=item aio_fdatasync $fh, $callback	539	=item aio_fdatasync $fh, $callback->($status)
221		540
222	Asynchronously call fdatasync on the given filehandle and call the	541	Asynchronously call fdatasync on the given filehandle and call the
223	callback with the fdatasync result code.	542	callback with the fdatasync result code.
		543
		544	If this call isn't available because your OS lacks it or it couldn't be
		545	detected, it will be emulated by calling C<fsync> instead.
		546
		547	=item aio_group $callback->(...)
		548
		549	[EXPERIMENTAL]
		550
		551	This is a very special aio request: Instead of doing something, it is a
		552	container for other aio requests, which is useful if you want to bundle
		553	many requests into a single, composite, request.
		554
		555	Returns an object of class L<IO::AIO::GRP>. See its documentation below
		556	for more info.
		557
		558	Example:
		559
		560	my $grp = aio_group sub {
		561	print "all stats done\n";
		562	};
		563
		564	add $grp
		565	(aio_stat ...),
		566	(aio_stat ...),
		567	...;
		568
		569	=item aio_nop $callback->()
		570
		571	This is a special request - it does nothing in itself and is only used for
		572	side effects, such as when you want to add a dummy request to a group so
		573	that finishing the requests in the group depends on executing the given
		574	code.
		575
		576	While this request does nothing, it still goes through the execution
		577	phase and still requires a worker thread. Thus, the callback will not
		578	be executed immediately but only after other requests in the queue have
		579	entered their execution phase. This can be used to measure request
		580	latency.
		581
		582	=item IO::AIO::aio_sleep $fractional_seconds, $callback->() NOT EXPORTED
		583
		584	Mainly used for debugging and benchmarking, this aio request puts one of
		585	the request workers to sleep for the given time.
		586
		587	While it is theoretically handy to have simple I/O scheduling requests
		588	like sleep and file handle readable/writable, the overhead this creates
		589	is immense, so do not use this function except to put your application
		590	under artificial I/O pressure.
		591
		592	=back
		593
		594	=head2 IO::AIO::REQ CLASS
		595
		596	All non-aggregate C<aio_*> functions return an object of this class when
		597	called in non-void context.
		598
		599	A request always moves through the following five states in its lifetime,
		600	in order: B<ready> (request has been created, but has not been executed
		601	yet), B<execute> (request is currently being executed), B<pending>
		602	(request has been executed but callback has not been called yet),
		603	B<result> (results are being processed synchronously, includes calling the
		604	callback) and B<done> (request has reached the end of its lifetime and
		605	holds no resources anymore).
		606
		607	=over 4
		608
		609	=item cancel $req
		610
		611	Cancels the request, if possible. Has the effect of skipping execution
		612	when entering the B<execute> state and skipping calling the callback when
		613	entering the the B<result> state, but will leave the request otherwise
		614	untouched. That means that requests that currently execute will not be
		615	stopped and resources held by the request will not be freed prematurely.
		616
		617	=item cb $req $callback->(...)
		618
		619	Replace (or simply set) the callback registered to the request.
		620
		621	=back
		622
		623	=head2 IO::AIO::GRP CLASS
		624
		625	This class is a subclass of L<IO::AIO::REQ>, so all its methods apply to
		626	objects of this class, too.
		627
		628	A IO::AIO::GRP object is a special request that can contain multiple other
		629	aio requests.
		630
		631	You create one by calling the C<aio_group> constructing function with a
		632	callback that will be called when all contained requests have entered the
		633	C<done> state:
		634
		635	my $grp = aio_group sub {
		636	print "all requests are done\n";
		637	};
		638
		639	You add requests by calling the C<add> method with one or more
		640	C<IO::AIO::REQ> objects:
		641
		642	$grp->add (aio_unlink "...");
		643
		644	add $grp aio_stat "...", sub {
		645	$_[0] or return $grp->result ("error");
		646
		647	# add another request dynamically, if first succeeded
		648	add $grp aio_open "...", sub {
		649	$grp->result ("ok");
		650	};
		651	};
		652
		653	This makes it very easy to create composite requests (see the source of
		654	C<aio_move> for an application) that work and feel like simple requests.
		655
		656	=over 4
		657
		658	=item * The IO::AIO::GRP objects will be cleaned up during calls to
		659	C<IO::AIO::poll_cb>, just like any other request.
		660
		661	=item * They can be canceled like any other request. Canceling will cancel not
		662	only the request itself, but also all requests it contains.
		663
		664	=item * They can also can also be added to other IO::AIO::GRP objects.
		665
		666	=item * You must not add requests to a group from within the group callback (or
		667	any later time).
		668
		669	=item * This does not harmonise well with C<max_outstanding>, so best do
		670	not combine C<aio_group> with it. Groups and feeders are recommended for
		671	this kind of concurrency-limiting.
		672
		673	=back
		674
		675	Their lifetime, simplified, looks like this: when they are empty, they
		676	will finish very quickly. If they contain only requests that are in the
		677	C<done> state, they will also finish. Otherwise they will continue to
		678	exist.
		679
		680	That means after creating a group you have some time to add requests. And
		681	in the callbacks of those requests, you can add further requests to the
		682	group. And only when all those requests have finished will the the group
		683	itself finish.
		684
		685	=over 4
		686
		687	=item add $grp ...
		688
		689	=item $grp->add (...)
		690
		691	Add one or more requests to the group. Any type of L<IO::AIO::REQ> can
		692	be added, including other groups, as long as you do not create circular
		693	dependencies.
		694
		695	Returns all its arguments.
		696
		697	=item $grp->result (...)
		698
		699	Set the result value(s) that will be passed to the group callback when all
		700	subrequests have finished. By default, no argument will be passed.
		701
		702	=item feed $grp $callback->($grp)
		703
		704	[VERY EXPERIMENTAL]
		705
		706	Sets a feeder/generator on this group: every group can have an attached
		707	generator that generates requests if idle. The idea behind this is that,
		708	although you could just queue as many requests as you want in a group,
		709	this might starve other requests for a potentially long time. For
		710	example, C<aio_scandir> might generate hundreds of thousands C<aio_stat>
		711	requests, delaying any later requests for a long time.
		712
		713	To avoid this, and allow incremental generation of requests, you can
		714	instead a group and set a feeder on it that generates those requests. The
		715	feed callback will be called whenever there are few enough (see C<limit>,
		716	below) requests active in the group itself and is expected to queue more
		717	requests.
		718
		719	The feed callback can queue as many requests as it likes (i.e. C<add> does
		720	not impose any limits).
		721
		722	If the feed does not queue more requests when called, it will be
		723	automatically removed from the group.
		724
		725	If the feed limit is C<0>, it will be set to C<2> automatically.
		726
		727	Example:
		728
		729	# stat all files in @files, but only ever use four aio requests concurrently:
		730
		731	my $grp = aio_group sub { print "finished\n" };
		732	limit $grp 4;
		733	feed $grp sub {
		734	my $file = pop @files
		735	or return;
		736
		737	add $grp aio_stat $file, sub { ... };
		738	};
		739
		740	=item limit $grp $num
		741
		742	Sets the feeder limit for the group: The feeder will be called whenever
		743	the group contains less than this many requests.
		744
		745	Setting the limit to C<0> will pause the feeding process.
		746
		747	=back
		748
		749	=head2 SUPPORT FUNCTIONS
		750
		751	=over 4
		752
		753	=item $fileno = IO::AIO::poll_fileno
		754
		755	Return the I<request result pipe file descriptor>. This filehandle must be
		756	polled for reading by some mechanism outside this module (e.g. Event or
		757	select, see below or the SYNOPSIS). If the pipe becomes readable you have
		758	to call C<poll_cb> to check the results.
		759
		760	See C<poll_cb> for an example.
		761
		762	=item IO::AIO::poll_cb
		763
		764	Process all outstanding events on the result pipe. You have to call this
		765	regularly. Returns the number of events processed. Returns immediately
		766	when no events are outstanding.
		767
		768	Example: Install an Event watcher that automatically calls
		769	IO::AIO::poll_cb with high priority:
		770
		771	Event->io (fd => IO::AIO::poll_fileno,
		772	poll => 'r', async => 1,
		773	cb => \&IO::AIO::poll_cb);
		774
		775	=item IO::AIO::poll_wait
		776
		777	Wait till the result filehandle becomes ready for reading (simply does a
		778	C<select> on the filehandle. This is useful if you want to synchronously wait
		779	for some requests to finish).
		780
		781	See C<nreqs> for an example.
		782
		783	=item IO::AIO::nreqs
		784
		785	Returns the number of requests currently outstanding (i.e. for which their
		786	callback has not been invoked yet).
		787
		788	Example: wait till there are no outstanding requests anymore:
		789
		790	IO::AIO::poll_wait, IO::AIO::poll_cb
		791	while IO::AIO::nreqs;
		792
		793	=item IO::AIO::flush
		794
		795	Wait till all outstanding AIO requests have been handled.
		796
		797	Strictly equivalent to:
		798
		799	IO::AIO::poll_wait, IO::AIO::poll_cb
		800	while IO::AIO::nreqs;
		801
		802	=item IO::AIO::poll
		803
		804	Waits until some requests have been handled.
		805
		806	Strictly equivalent to:
		807
		808	IO::AIO::poll_wait, IO::AIO::poll_cb
		809	if IO::AIO::nreqs;
		810
		811	=item IO::AIO::min_parallel $nthreads
		812
		813	Set the minimum number of AIO threads to C<$nthreads>. The current
		814	default is C<8>, which means eight asynchronous operations can execute
		815	concurrently at any one time (the number of outstanding requests,
		816	however, is unlimited).
		817
		818	IO::AIO starts threads only on demand, when an AIO request is queued and
		819	no free thread exists.
		820
		821	It is recommended to keep the number of threads relatively low, as some
		822	Linux kernel versions will scale negatively with the number of threads
		823	(higher parallelity => MUCH higher latency). With current Linux 2.6
		824	versions, 4-32 threads should be fine.
		825
		826	Under most circumstances you don't need to call this function, as the
		827	module selects a default that is suitable for low to moderate load.
		828
		829	=item IO::AIO::max_parallel $nthreads
		830
		831	Sets the maximum number of AIO threads to C<$nthreads>. If more than the
		832	specified number of threads are currently running, this function kills
		833	them. This function blocks until the limit is reached.
		834
		835	While C<$nthreads> are zero, aio requests get queued but not executed
		836	until the number of threads has been increased again.
		837
		838	This module automatically runs C<max_parallel 0> at program end, to ensure
		839	that all threads are killed and that there are no outstanding requests.
		840
		841	Under normal circumstances you don't need to call this function.
		842
		843	=item $oldnreqs = IO::AIO::max_outstanding $nreqs
		844
		845	[DEPRECATED]
		846
		847	Sets the maximum number of outstanding requests to C<$nreqs>. If you
		848	try to queue up more than this number of requests, the caller will block until
		849	some requests have been handled.
		850
		851	The default is very large, so normally there is no practical limit. If you
		852	queue up many requests in a loop it often improves speed if you set
		853	this to a relatively low number, such as C<100>.
		854
		855	This function does not work well together with C<aio_group>'s, and their
		856	feeder interface is better suited to limiting concurrency, so do not use
		857	this function.
		858
		859	Under normal circumstances you don't need to call this function.
		860
		861	=back
224		862
225	=cut	863	=cut
226		864
227	# support function to convert a fd into a perl filehandle	865	# support function to convert a fd into a perl filehandle
228	sub _fd2fh {	866	sub _fd2fh {
229	return undef if $_[0] < 0;	867	return undef if $_[0] < 0;
230		868
231	# try to be perl5.6-compatible	869	# try to generate nice filehandles
232	local *AIO_FH;	870	my $sym = "IO::AIO::fd#$_[0]";
233	open AIO_FH, "+<&=$_[0]"	871	local *$sym;
		872
		873	open *$sym, "+<&=$_[0]" # usually works under any unix
		874	or open *$sym, "<&=$_[0]" # cygwin needs this
		875	or open *$sym, ">&=$_[0]" # or this
234	or return undef;	876	or return undef;
235		877
236	*AIO_FH	878	*$sym
237	}	879	}
238		880
239	min_parallel 4;	881	min_parallel 8;
240		882
241	END {	883	END {
242	max_parallel 0;	884	max_parallel 0;
243	}	885	}
244		886
245	1;	887	1;
246		888
247	=back	889	=head2 FORK BEHAVIOUR
248		890
249	=head1 BUGS	891	This module should do "the right thing" when the process using it forks:
250		892
251	- could be optimized to use more semaphores instead of filehandles.	893	Before the fork, IO::AIO enters a quiescent state where no requests
		894	can be added in other threads and no results will be processed. After
		895	the fork the parent simply leaves the quiescent state and continues
		896	request/result processing, while the child clears the request/result
		897	queue (so the requests started before the fork will only be handled in
		898	the parent). Threads will be started on demand until the limit ste in the
		899	parent process has been reached again.
		900
		901	In short: the parent will, after a short pause, continue as if fork had
		902	not been called, while the child will act as if IO::AIO has not been used
		903	yet.
		904
		905	=head2 MEMORY USAGE
		906
		907	Each aio request uses - depending on your architecture - around 128 bytes
		908	of memory. In addition, stat requests need a stat buffer (possibly a few
		909	hundred bytes). Perl scalars and other data passed into aio requests will
		910	also be locked.
		911
		912	This is now awfully much, so queuing lots of requests is not usually a
		913	problem.
		914
		915	Each thread needs a stack area which is usually around 16k, sometimes much
		916	larger, depending on the OS.
252		917
253	=head1 SEE ALSO	918	=head1 SEE ALSO
254		919
255	L<Coro>, L<Linux::AIO>.	920	L<Coro::AIO>.
256		921
257	=head1 AUTHOR	922	=head1 AUTHOR
258		923
259	Marc Lehmann <schmorp@schmorp.de>	924	Marc Lehmann <schmorp@schmorp.de>
260	http://home.schmorp.de/	925	http://home.schmorp.de/

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Revision 1.70 by root, Tue Oct 24 03:40:38 2006 UTC