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

Comparing IO-AIO/AIO.pm (file contents):
Revision 1.49 by root, Wed Mar 1 23:56:54 2006 UTC vs.
Revision 1.91 by root, Mon Oct 30 23:30:29 2006 UTC

…		…
15		15
16	aio_read $fh, 30000, 1024, $buffer, 0, sub {	16	aio_read $fh, 30000, 1024, $buffer, 0, sub {
17	$_[0] > 0 or die "read error: $!";	17	$_[0] > 0 or die "read error: $!";
18	};	18	};
19		19
20	# AnyEvent	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
21	open my $fh, "<&=" . IO::AIO::poll_fileno or die "$!";	31	open my $fh, "<&=" . IO::AIO::poll_fileno or die "$!";
22	my $w = AnyEvent->io (fh => $fh, poll => 'r', cb => sub { IO::AIO::poll_cb });	32	my $w = AnyEvent->io (fh => $fh, poll => 'r', cb => sub { IO::AIO::poll_cb });
23		33
24	# Event	34	# Event integration
25	Event->io (fd => IO::AIO::poll_fileno,	35	Event->io (fd => IO::AIO::poll_fileno,
26	poll => 'r',	36	poll => 'r',
27	cb => \&IO::AIO::poll_cb);	37	cb => \&IO::AIO::poll_cb);
28		38
29	# Glib/Gtk2	39	# Glib/Gtk2 integration
30	add_watch Glib::IO IO::AIO::poll_fileno,	40	add_watch Glib::IO IO::AIO::poll_fileno,
31	in => sub { IO::AIO::poll_cb; 1 };	41	in => sub { IO::AIO::poll_cb; 1 };
32		42
33	# Tk	43	# Tk integration
34	Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",	44	Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
35	readable => \&IO::AIO::poll_cb);	45	readable => \&IO::AIO::poll_cb);
36		46
37	# Danga::Socket	47	# Danga::Socket integration
38	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>	48	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
39	\&IO::AIO::poll_cb);	49	\&IO::AIO::poll_cb);
40		50
41
42	=head1 DESCRIPTION	51	=head1 DESCRIPTION
43		52
44	This module implements asynchronous I/O using whatever means your	53	This module implements asynchronous I/O using whatever means your
45	operating system supports.	54	operating system supports.
46		55
		56	Asynchronous means that operations that can normally block your program
		57	(e.g. reading from disk) will be done asynchronously: the operation
		58	will still block, but you can do something else in the meantime. This
		59	is extremely useful for programs that need to stay interactive even
		60	when doing heavy I/O (GUI programs, high performance network servers
		61	etc.), but can also be used to easily do operations in parallel that are
		62	normally done sequentially, e.g. stat'ing many files, which is much faster
		63	on a RAID volume or over NFS when you do a number of stat operations
		64	concurrently.
		65
		66	While most of this works on all types of file descriptors (for example
		67	sockets), using these functions on file descriptors that support
		68	nonblocking operation (again, sockets, pipes etc.) is very inefficient or
		69	might not work (aio_read fails on sockets/pipes/fifos). Use an event loop
		70	for that (such as the L<Event\|Event> module): IO::AIO will naturally fit
		71	into such an event loop itself.
		72
47	Currently, a number of threads are started that execute your read/writes	73	In this version, a number of threads are started that execute your
48	and signal their completion. You don't need thread support in your libc or	74	requests and signal their completion. You don't need thread support
49	perl, and the threads created by this module will not be visible to the	75	in perl, and the threads created by this module will not be visible
50	pthreads library. In the future, this module might make use of the native	76	to perl. In the future, this module might make use of the native aio
51	aio functions available on many operating systems. However, they are often	77	functions available on many operating systems. However, they are often
52	not well-supported (Linux doesn't allow them on normal files currently,	78	not well-supported or restricted (GNU/Linux doesn't allow them on normal
53	for example), and they would only support aio_read and aio_write, so the	79	files currently, for example), and they would only support aio_read and
54	remaining functionality would have to be implemented using threads anyway.	80	aio_write, so the remaining functionality would have to be implemented
		81	using threads anyway.
55		82
56	Although the module will work with in the presence of other threads, it is	83	Although the module will work with in the presence of other (Perl-)
57	currently not reentrant, so use appropriate locking yourself, always call	84	threads, it is currently not reentrant in any way, so use appropriate
58	C<poll_cb> from within the same thread, or never call C<poll_cb> (or other	85	locking yourself, always call C<poll_cb> from within the same thread, or
59	C<aio_> functions) recursively.	86	never call C<poll_cb> (or other C<aio_> functions) recursively.
		87
		88	=head2 EXAMPLE
		89
		90	This is a simple example that uses the Event module and loads
		91	F</etc/passwd> asynchronously:
		92
		93	use Fcntl;
		94	use Event;
		95	use IO::AIO;
		96
		97	# register the IO::AIO callback with Event
		98	Event->io (fd => IO::AIO::poll_fileno,
		99	poll => 'r',
		100	cb => \&IO::AIO::poll_cb);
		101
		102	# queue the request to open /etc/passwd
		103	aio_open "/etc/passwd", O_RDONLY, 0, sub {
		104	my $fh = $_[0]
		105	or die "error while opening: $!";
		106
		107	# stat'ing filehandles is generally non-blocking
		108	my $size = -s $fh;
		109
		110	# queue a request to read the file
		111	my $contents;
		112	aio_read $fh, 0, $size, $contents, 0, sub {
		113	$_[0] == $size
		114	or die "short read: $!";
		115
		116	close $fh;
		117
		118	# file contents now in $contents
		119	print $contents;
		120
		121	# exit event loop and program
		122	Event::unloop;
		123	};
		124	};
		125
		126	# possibly queue up other requests, or open GUI windows,
		127	# check for sockets etc. etc.
		128
		129	# process events as long as there are some:
		130	Event::loop;
		131
		132	=head1 REQUEST ANATOMY AND LIFETIME
		133
		134	Every C<aio_*> function creates a request. which is a C data structure not
		135	directly visible to Perl.
		136
		137	If called in non-void context, every request function returns a Perl
		138	object representing the request. In void context, nothing is returned,
		139	which saves a bit of memory.
		140
		141	The perl object is a fairly standard ref-to-hash object. The hash contents
		142	are not used by IO::AIO so you are free to store anything you like in it.
		143
		144	During their existance, aio requests travel through the following states,
		145	in order:
		146
		147	=over 4
		148
		149	=item ready
		150
		151	Immediately after a request is created it is put into the ready state,
		152	waiting for a thread to execute it.
		153
		154	=item execute
		155
		156	A thread has accepted the request for processing and is currently
		157	executing it (e.g. blocking in read).
		158
		159	=item pending
		160
		161	The request has been executed and is waiting for result processing.
		162
		163	While request submission and execution is fully asynchronous, result
		164	processing is not and relies on the perl interpreter calling C<poll_cb>
		165	(or another function with the same effect).
		166
		167	=item result
		168
		169	The request results are processed synchronously by C<poll_cb>.
		170
		171	The C<poll_cb> function will process all outstanding aio requests by
		172	calling their callbacks, freeing memory associated with them and managing
		173	any groups they are contained in.
		174
		175	=item done
		176
		177	Request has reached the end of its lifetime and holds no resources anymore
		178	(except possibly for the Perl object, but its connection to the actual
		179	aio request is severed and calling its methods will either do nothing or
		180	result in a runtime error).
		181
		182	=back
60		183
61	=cut	184	=cut
62		185
63	package IO::AIO;	186	package IO::AIO;
64		187
65	no warnings;	188	no warnings;
		189	use strict 'vars';
66		190
67	use base 'Exporter';	191	use base 'Exporter';
68		192
69	use Fcntl ();
70
71	BEGIN {	193	BEGIN {
72	$VERSION = '1.73';	194	our $VERSION = '2.2';
73		195
74	@EXPORT = qw(aio_sendfile aio_read aio_write aio_open aio_close aio_stat	196	our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close aio_stat
75	aio_lstat aio_unlink aio_rmdir aio_readdir aio_scandir aio_symlink	197	aio_lstat aio_unlink aio_rmdir aio_readdir aio_scandir aio_symlink
76	aio_fsync aio_fdatasync aio_readahead);	198	aio_readlink aio_fsync aio_fdatasync aio_readahead aio_rename aio_link
77	@EXPORT_OK = qw(poll_fileno poll_cb min_parallel max_parallel	199	aio_move aio_copy aio_group aio_nop aio_mknod);
78	max_outstanding nreqs);	200	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
		201	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
		202	min_parallel max_parallel max_idle
		203	nreqs nready npending nthreads
		204	max_poll_time max_poll_reqs);
		205
		206	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';
79		207
80	require XSLoader;	208	require XSLoader;
81	XSLoader::load IO::AIO, $VERSION;	209	XSLoader::load ("IO::AIO", $VERSION);
82	}	210	}
83		211
84	=head1 FUNCTIONS	212	=head1 FUNCTIONS
85		213
86	=head2 AIO FUNCTIONS	214	=head2 AIO REQUEST FUNCTIONS
87		215
88	All the C<aio_*> calls are more or less thin wrappers around the syscall	216	All the C<aio_*> calls are more or less thin wrappers around the syscall
89	with the same name (sans C<aio_>). The arguments are similar or identical,	217	with the same name (sans C<aio_>). The arguments are similar or identical,
90	and they all accept an additional (and optional) C<$callback> argument	218	and they all accept an additional (and optional) C<$callback> argument
91	which must be a code reference. This code reference will get called with	219	which must be a code reference. This code reference will get called with
…		…
94	syscall has been executed asynchronously.	222	syscall has been executed asynchronously.
95		223
96	All functions expecting a filehandle keep a copy of the filehandle	224	All functions expecting a filehandle keep a copy of the filehandle
97	internally until the request has finished.	225	internally until the request has finished.
98		226
		227	All functions return request objects of type L<IO::AIO::REQ> that allow
		228	further manipulation of those requests while they are in-flight.
		229
99	The pathnames you pass to these routines I<must> be absolute and	230	The pathnames you pass to these routines I<must> be absolute and
100	encoded in byte form. The reason for the former is that at the time the	231	encoded as octets. The reason for the former is that at the time the
101	request is being executed, the current working directory could have	232	request is being executed, the current working directory could have
102	changed. Alternatively, you can make sure that you never change the	233	changed. Alternatively, you can make sure that you never change the
103	current working directory.	234	current working directory anywhere in the program and then use relative
		235	paths.
104		236
105	To encode pathnames to byte form, either make sure you either: a)	237	To encode pathnames as octets, either make sure you either: a) always pass
106	always pass in filenames you got from outside (command line, readdir	238	in filenames you got from outside (command line, readdir etc.) without
107	etc.), b) are ASCII or ISO 8859-1, c) use the Encode module and encode	239	tinkering, b) are ASCII or ISO 8859-1, c) use the Encode module and encode
108	your pathnames to the locale (or other) encoding in effect in the user	240	your pathnames to the locale (or other) encoding in effect in the user
109	environment, d) use Glib::filename_from_unicode on unicode filenames or e)	241	environment, d) use Glib::filename_from_unicode on unicode filenames or e)
110	use something else.	242	use something else to ensure your scalar has the correct contents.
		243
		244	This works, btw. independent of the internal UTF-8 bit, which IO::AIO
		245	handles correctly wether it is set or not.
111		246
112	=over 4	247	=over 4
		248
		249	=item $prev_pri = aioreq_pri [$pri]
		250
		251	Returns the priority value that would be used for the next request and, if
		252	C<$pri> is given, sets the priority for the next aio request.
		253
		254	The default priority is C<0>, the minimum and maximum priorities are C<-4>
		255	and C<4>, respectively. Requests with higher priority will be serviced
		256	first.
		257
		258	The priority will be reset to C<0> after each call to one of the C<aio_*>
		259	functions.
		260
		261	Example: open a file with low priority, then read something from it with
		262	higher priority so the read request is serviced before other low priority
		263	open requests (potentially spamming the cache):
		264
		265	aioreq_pri -3;
		266	aio_open ..., sub {
		267	return unless $_[0];
		268
		269	aioreq_pri -2;
		270	aio_read $_[0], ..., sub {
		271	...
		272	};
		273	};
		274
		275	=item aioreq_nice $pri_adjust
		276
		277	Similar to C<aioreq_pri>, but subtracts the given value from the current
		278	priority, so the effect is cumulative.
113		279
114	=item aio_open $pathname, $flags, $mode, $callback->($fh)	280	=item aio_open $pathname, $flags, $mode, $callback->($fh)
115		281
116	Asynchronously open or create a file and call the callback with a newly	282	Asynchronously open or create a file and call the callback with a newly
117	created filehandle for the file.	283	created filehandle for the file.
…		…
232	=item aio_unlink $pathname, $callback->($status)	398	=item aio_unlink $pathname, $callback->($status)
233		399
234	Asynchronously unlink (delete) a file and call the callback with the	400	Asynchronously unlink (delete) a file and call the callback with the
235	result code.	401	result code.
236		402
		403	=item aio_mknod $path, $mode, $dev, $callback->($status)
		404
		405	[EXPERIMENTAL]
		406
		407	Asynchronously create a device node (or fifo). See mknod(2).
		408
		409	The only (POSIX-) portable way of calling this function is:
		410
		411	aio_mknod $path, IO::AIO::S_IFIFO \| $mode, 0, sub { ...
		412
		413	=item aio_link $srcpath, $dstpath, $callback->($status)
		414
		415	Asynchronously create a new link to the existing object at C<$srcpath> at
		416	the path C<$dstpath> and call the callback with the result code.
		417
		418	=item aio_symlink $srcpath, $dstpath, $callback->($status)
		419
		420	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at
		421	the path C<$dstpath> and call the callback with the result code.
		422
		423	=item aio_readlink $path, $callback->($link)
		424
		425	Asynchronously read the symlink specified by C<$path> and pass it to
		426	the callback. If an error occurs, nothing or undef gets passed to the
		427	callback.
		428
		429	=item aio_rename $srcpath, $dstpath, $callback->($status)
		430
		431	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
		432	rename(2) and call the callback with the result code.
		433
237	=item aio_rmdir $pathname, $callback->($status)	434	=item aio_rmdir $pathname, $callback->($status)
238		435
239	Asynchronously rmdir (delete) a directory and call the callback with the	436	Asynchronously rmdir (delete) a directory and call the callback with the
240	result code.	437	result code.
241		438
…		…
246	sorted, and will B<NOT> include the C<.> and C<..> entries.	443	sorted, and will B<NOT> include the C<.> and C<..> entries.
247		444
248	The callback a single argument which is either C<undef> or an array-ref	445	The callback a single argument which is either C<undef> or an array-ref
249	with the filenames.	446	with the filenames.
250		447
		448	=item aio_copy $srcpath, $dstpath, $callback->($status)
		449
		450	Try to copy the I<file> (directories not supported as either source or
		451	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		452	the C<0> (error) or C<-1> ok.
		453
		454	This is a composite request that it creates the destination file with
		455	mode 0200 and copies the contents of the source file into it using
		456	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
		457	uid/gid, in that order.
		458
		459	If an error occurs, the partial destination file will be unlinked, if
		460	possible, except when setting atime, mtime, access mode and uid/gid, where
		461	errors are being ignored.
		462
		463	=cut
		464
		465	sub aio_copy($$;$) {
		466	my ($src, $dst, $cb) = @_;
		467
		468	my $pri = aioreq_pri;
		469	my $grp = aio_group $cb;
		470
		471	aioreq_pri $pri;
		472	add $grp aio_open $src, O_RDONLY, 0, sub {
		473	if (my $src_fh = $_[0]) {
		474	my @stat = stat $src_fh;
		475
		476	aioreq_pri $pri;
		477	add $grp aio_open $dst, O_CREAT \| O_WRONLY \| O_TRUNC, 0200, sub {
		478	if (my $dst_fh = $_[0]) {
		479	aioreq_pri $pri;
		480	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
		481	if ($_[0] == $stat[7]) {
		482	$grp->result (0);
		483	close $src_fh;
		484
		485	# those should not normally block. should. should.
		486	utime $stat[8], $stat[9], $dst;
		487	chmod $stat[2] & 07777, $dst_fh;
		488	chown $stat[4], $stat[5], $dst_fh;
		489	close $dst_fh;
		490	} else {
		491	$grp->result (-1);
		492	close $src_fh;
		493	close $dst_fh;
		494
		495	aioreq $pri;
		496	add $grp aio_unlink $dst;
		497	}
		498	};
		499	} else {
		500	$grp->result (-1);
		501	}
		502	},
		503
		504	} else {
		505	$grp->result (-1);
		506	}
		507	};
		508
		509	$grp
		510	}
		511
		512	=item aio_move $srcpath, $dstpath, $callback->($status)
		513
		514	Try to move the I<file> (directories not supported as either source or
		515	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		516	the C<0> (error) or C<-1> ok.
		517
		518	This is a composite request that tries to rename(2) the file first. If
		519	rename files with C<EXDEV>, it copies the file with C<aio_copy> and, if
		520	that is successful, unlinking the C<$srcpath>.
		521
		522	=cut
		523
		524	sub aio_move($$;$) {
		525	my ($src, $dst, $cb) = @_;
		526
		527	my $pri = aioreq_pri;
		528	my $grp = aio_group $cb;
		529
		530	aioreq_pri $pri;
		531	add $grp aio_rename $src, $dst, sub {
		532	if ($_[0] && $! == EXDEV) {
		533	aioreq_pri $pri;
		534	add $grp aio_copy $src, $dst, sub {
		535	$grp->result ($_[0]);
		536
		537	if (!$_[0]) {
		538	aioreq_pri $pri;
		539	add $grp aio_unlink $src;
		540	}
		541	};
		542	} else {
		543	$grp->result ($_[0]);
		544	}
		545	};
		546
		547	$grp
		548	}
		549
251	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	550	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
252		551
253	Scans a directory (similar to C<aio_readdir>) and tries to separate the	552	Scans a directory (similar to C<aio_readdir>) but additionally tries to
254	entries of directory C<$path> into two sets of names, ones you can recurse	553	efficiently separate the entries of directory C<$path> into two sets of
255	into (directories), and ones you cannot recurse into (everything else).	554	names, directories you can recurse into (directories), and ones you cannot
		555	recurse into (everything else, including symlinks to directories).
256		556
257	C<aio_scandir> is a composite request that consists of many	557	C<aio_scandir> is a composite request that creates of many sub requests_
258	aio-primitives. C<$maxreq> specifies the maximum number of outstanding	558	C<$maxreq> specifies the maximum number of outstanding aio requests that
259	aio requests that this function generates. If it is C<< <= 0 >>, then a	559	this function generates. If it is C<< <= 0 >>, then a suitable default
260	suitable default will be chosen (currently 8).	560	will be chosen (currently 4).
261		561
262	On error, the callback is called without arguments, otherwise it receives	562	On error, the callback is called without arguments, otherwise it receives
263	two array-refs with path-relative entry names.	563	two array-refs with path-relative entry names.
264		564
265	Example:	565	Example:
…		…
273	Implementation notes.	573	Implementation notes.
274		574
275	The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can.	575	The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can.
276		576
277	After reading the directory, the modification time, size etc. of the	577	After reading the directory, the modification time, size etc. of the
278	directory before and after the readdir is checked, and if they match, the	578	directory before and after the readdir is checked, and if they match (and
279	link count will be used to decide how many entries are directories (if	579	isn't the current time), the link count will be used to decide how many
280	>= 2). Otherwise, no knowledge of the number of subdirectories will be	580	entries are directories (if >= 2). Otherwise, no knowledge of the number
281	assumed.	581	of subdirectories will be assumed.
282		582
283	Then entires will be sorted into likely directories (everything without a	583	Then entries will be sorted into likely directories (everything without
284	non-initial dot) and likely non-directories (everything else). Then every	584	a non-initial dot currently) and likely non-directories (everything
285	entry + C</.> will be C<stat>'ed, likely directories first. This is often	585	else). Then every entry plus an appended C</.> will be C<stat>'ed,
		586	likely directories first. If that succeeds, it assumes that the entry
		587	is a directory or a symlink to directory (which will be checked
		588	seperately). This is often faster than stat'ing the entry itself because
286	faster because filesystems might detect the type of the entry without	589	filesystems might detect the type of the entry without reading the inode
287	reading the inode data (e.g. ext2fs filetype feature). If that succeeds,	590	data (e.g. ext2fs filetype feature).
288	it assumes that the entry is a directory or a symlink to directory (which
289	will be checked seperately).
290		591
291	If the known number of directories has been reached, the rest of the	592	If the known number of directories (link count - 2) has been reached, the
292	entries is assumed to be non-directories.	593	rest of the entries is assumed to be non-directories.
		594
		595	This only works with certainty on POSIX (= UNIX) filesystems, which
		596	fortunately are the vast majority of filesystems around.
		597
		598	It will also likely work on non-POSIX filesystems with reduced efficiency
		599	as those tend to return 0 or 1 as link counts, which disables the
		600	directory counting heuristic.
293		601
294	=cut	602	=cut
295		603
296	sub aio_scandir($$$) {	604	sub aio_scandir($$$) {
297	my ($path, $maxreq, $cb) = @_;	605	my ($path, $maxreq, $cb) = @_;
298		606
		607	my $pri = aioreq_pri;
		608
		609	my $grp = aio_group $cb;
		610
299	$maxreq = 8 if $maxreq <= 0;	611	$maxreq = 4 if $maxreq <= 0;
300		612
301	# stat once	613	# stat once
		614	aioreq_pri $pri;
302	aio_stat $path, sub {	615	add $grp aio_stat $path, sub {
303	return $cb->() if $_[0];	616	return $grp->result () if $_[0];
		617	my $now = time;
304	my $hash1 = join ":", (stat _)[0,1,3,7,9];	618	my $hash1 = join ":", (stat _)[0,1,3,7,9];
305		619
306	# read the directory entries	620	# read the directory entries
		621	aioreq_pri $pri;
307	aio_readdir $path, sub {	622	add $grp aio_readdir $path, sub {
308	my $entries = shift	623	my $entries = shift
309	or return $cb->();	624	or return $grp->result ();
310		625
311	# stat the dir another time	626	# stat the dir another time
		627	aioreq_pri $pri;
312	aio_stat $path, sub {	628	add $grp aio_stat $path, sub {
313	my $hash2 = join ":", (stat _)[0,1,3,7,9];	629	my $hash2 = join ":", (stat _)[0,1,3,7,9];
314		630
315	my $ndirs;	631	my $ndirs;
316		632
317	# take the slow route if anything looks fishy	633	# take the slow route if anything looks fishy
318	if ($hash1 ne $hash2) {	634	if ($hash1 ne $hash2 or (stat _)[9] == $now) {
319	$ndirs = -1;	635	$ndirs = -1;
320	} else {	636	} else {
321	# if nlink == 2, we are finished	637	# if nlink == 2, we are finished
322	# on non-posix-fs's, we rely on nlink < 2	638	# on non-posix-fs's, we rely on nlink < 2
323	$ndirs = (stat _)[3] - 2	639	$ndirs = (stat _)[3] - 2
324	or return $cb->([], $entries);	640	or return $grp->result ([], $entries);
325	}	641	}
326		642
327	# sort into likely dirs and likely nondirs	643	# sort into likely dirs and likely nondirs
328	# dirs == files without ".", short entries first	644	# dirs == files without ".", short entries first
329	$entries = [map $_->[0],	645	$entries = [map $_->[0],
…		…
331	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],	647	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
332	@$entries];	648	@$entries];
333		649
334	my (@dirs, @nondirs);	650	my (@dirs, @nondirs);
335		651
336	my ($statcb, $schedcb);	652	my $statgrp = add $grp aio_group sub {
337	my $nreq = 0;	653	$grp->result (\@dirs, \@nondirs);
		654	};
338		655
339	$schedcb = sub {	656	limit $statgrp $maxreq;
340	if (@$entries) {	657	feed $statgrp sub {
341	if ($nreq < $maxreq) {	658	return unless @$entries;
342	my $ent = pop @$entries;	659	my $entry = pop @$entries;
		660
		661	aioreq_pri $pri;
		662	add $statgrp aio_stat "$path/$entry/.", sub {
		663	if ($_[0] < 0) {
		664	push @nondirs, $entry;
		665	} else {
		666	# need to check for real directory
		667	aioreq_pri $pri;
		668	add $statgrp aio_lstat "$path/$entry", sub {
		669	if (-d _) {
		670	push @dirs, $entry;
		671
		672	unless (--$ndirs) {
		673	push @nondirs, @$entries;
		674	feed $statgrp;
		675	}
		676	} else {
		677	push @nondirs, $entry;
		678	}
343	$nreq++;	679	}
344	aio_stat "$path/$ent/.", sub { $statcb->($_[0], $ent) };
345	}	680	}
346	} elsif (!$nreq) {
347	# finished
348	undef $statcb;
349	undef $schedcb;
350	$cb->(\@dirs, \@nondirs) if $cb;
351	undef $cb;
352	}	681	};
353	};	682	};
354	$statcb = sub {
355	my ($status, $entry) = @_;
356
357	if ($status < 0) {
358	$nreq--;
359	push @nondirs, $entry;
360	&$schedcb;
361	} else {
362	# need to check for real directory
363	aio_lstat "$path/$entry", sub {
364	$nreq--;
365
366	if (-d _) {
367	push @dirs, $entry;
368
369	if (!--$ndirs) {
370	push @nondirs, @$entries;
371	$entries = [];
372	}
373	} else {
374	push @nondirs, $entry;
375	}
376
377	&$schedcb;
378	}
379	}
380	};
381
382	&$schedcb while @$entries && $nreq < $maxreq;
383	};	683	};
384	};	684	};
385	};	685	};
		686
		687	$grp
386	}	688	}
387		689
388	=item aio_fsync $fh, $callback->($status)	690	=item aio_fsync $fh, $callback->($status)
389		691
390	Asynchronously call fsync on the given filehandle and call the callback	692	Asynchronously call fsync on the given filehandle and call the callback
…		…
396	callback with the fdatasync result code.	698	callback with the fdatasync result code.
397		699
398	If this call isn't available because your OS lacks it or it couldn't be	700	If this call isn't available because your OS lacks it or it couldn't be
399	detected, it will be emulated by calling C<fsync> instead.	701	detected, it will be emulated by calling C<fsync> instead.
400		702
		703	=item aio_group $callback->(...)
		704
		705	This is a very special aio request: Instead of doing something, it is a
		706	container for other aio requests, which is useful if you want to bundle
		707	many requests into a single, composite, request with a definite callback
		708	and the ability to cancel the whole request with its subrequests.
		709
		710	Returns an object of class L<IO::AIO::GRP>. See its documentation below
		711	for more info.
		712
		713	Example:
		714
		715	my $grp = aio_group sub {
		716	print "all stats done\n";
		717	};
		718
		719	add $grp
		720	(aio_stat ...),
		721	(aio_stat ...),
		722	...;
		723
		724	=item aio_nop $callback->()
		725
		726	This is a special request - it does nothing in itself and is only used for
		727	side effects, such as when you want to add a dummy request to a group so
		728	that finishing the requests in the group depends on executing the given
		729	code.
		730
		731	While this request does nothing, it still goes through the execution
		732	phase and still requires a worker thread. Thus, the callback will not
		733	be executed immediately but only after other requests in the queue have
		734	entered their execution phase. This can be used to measure request
		735	latency.
		736
		737	=item IO::AIO::aio_busy $fractional_seconds, $callback->() NOT EXPORTED
		738
		739	Mainly used for debugging and benchmarking, this aio request puts one of
		740	the request workers to sleep for the given time.
		741
		742	While it is theoretically handy to have simple I/O scheduling requests
		743	like sleep and file handle readable/writable, the overhead this creates is
		744	immense (it blocks a thread for a long time) so do not use this function
		745	except to put your application under artificial I/O pressure.
		746
401	=back	747	=back
402		748
		749	=head2 IO::AIO::REQ CLASS
		750
		751	All non-aggregate C<aio_*> functions return an object of this class when
		752	called in non-void context.
		753
		754	=over 4
		755
		756	=item cancel $req
		757
		758	Cancels the request, if possible. Has the effect of skipping execution
		759	when entering the B<execute> state and skipping calling the callback when
		760	entering the the B<result> state, but will leave the request otherwise
		761	untouched. That means that requests that currently execute will not be
		762	stopped and resources held by the request will not be freed prematurely.
		763
		764	=item cb $req $callback->(...)
		765
		766	Replace (or simply set) the callback registered to the request.
		767
		768	=back
		769
		770	=head2 IO::AIO::GRP CLASS
		771
		772	This class is a subclass of L<IO::AIO::REQ>, so all its methods apply to
		773	objects of this class, too.
		774
		775	A IO::AIO::GRP object is a special request that can contain multiple other
		776	aio requests.
		777
		778	You create one by calling the C<aio_group> constructing function with a
		779	callback that will be called when all contained requests have entered the
		780	C<done> state:
		781
		782	my $grp = aio_group sub {
		783	print "all requests are done\n";
		784	};
		785
		786	You add requests by calling the C<add> method with one or more
		787	C<IO::AIO::REQ> objects:
		788
		789	$grp->add (aio_unlink "...");
		790
		791	add $grp aio_stat "...", sub {
		792	$_[0] or return $grp->result ("error");
		793
		794	# add another request dynamically, if first succeeded
		795	add $grp aio_open "...", sub {
		796	$grp->result ("ok");
		797	};
		798	};
		799
		800	This makes it very easy to create composite requests (see the source of
		801	C<aio_move> for an application) that work and feel like simple requests.
		802
		803	=over 4
		804
		805	=item * The IO::AIO::GRP objects will be cleaned up during calls to
		806	C<IO::AIO::poll_cb>, just like any other request.
		807
		808	=item * They can be canceled like any other request. Canceling will cancel not
		809	only the request itself, but also all requests it contains.
		810
		811	=item * They can also can also be added to other IO::AIO::GRP objects.
		812
		813	=item * You must not add requests to a group from within the group callback (or
		814	any later time).
		815
		816	=back
		817
		818	Their lifetime, simplified, looks like this: when they are empty, they
		819	will finish very quickly. If they contain only requests that are in the
		820	C<done> state, they will also finish. Otherwise they will continue to
		821	exist.
		822
		823	That means after creating a group you have some time to add requests. And
		824	in the callbacks of those requests, you can add further requests to the
		825	group. And only when all those requests have finished will the the group
		826	itself finish.
		827
		828	=over 4
		829
		830	=item add $grp ...
		831
		832	=item $grp->add (...)
		833
		834	Add one or more requests to the group. Any type of L<IO::AIO::REQ> can
		835	be added, including other groups, as long as you do not create circular
		836	dependencies.
		837
		838	Returns all its arguments.
		839
		840	=item $grp->cancel_subs
		841
		842	Cancel all subrequests and clears any feeder, but not the group request
		843	itself. Useful when you queued a lot of events but got a result early.
		844
		845	=item $grp->result (...)
		846
		847	Set the result value(s) that will be passed to the group callback when all
		848	subrequests have finished and set thre groups errno to the current value
		849	of errno (just like calling C<errno> without an error number). By default,
		850	no argument will be passed and errno is zero.
		851
		852	=item $grp->errno ([$errno])
		853
		854	Sets the group errno value to C<$errno>, or the current value of errno
		855	when the argument is missing.
		856
		857	Every aio request has an associated errno value that is restored when
		858	the callback is invoked. This method lets you change this value from its
		859	default (0).
		860
		861	Calling C<result> will also set errno, so make sure you either set C<$!>
		862	before the call to C<result>, or call c<errno> after it.
		863
		864	=item feed $grp $callback->($grp)
		865
		866	Sets a feeder/generator on this group: every group can have an attached
		867	generator that generates requests if idle. The idea behind this is that,
		868	although you could just queue as many requests as you want in a group,
		869	this might starve other requests for a potentially long time. For
		870	example, C<aio_scandir> might generate hundreds of thousands C<aio_stat>
		871	requests, delaying any later requests for a long time.
		872
		873	To avoid this, and allow incremental generation of requests, you can
		874	instead a group and set a feeder on it that generates those requests. The
		875	feed callback will be called whenever there are few enough (see C<limit>,
		876	below) requests active in the group itself and is expected to queue more
		877	requests.
		878
		879	The feed callback can queue as many requests as it likes (i.e. C<add> does
		880	not impose any limits).
		881
		882	If the feed does not queue more requests when called, it will be
		883	automatically removed from the group.
		884
		885	If the feed limit is C<0>, it will be set to C<2> automatically.
		886
		887	Example:
		888
		889	# stat all files in @files, but only ever use four aio requests concurrently:
		890
		891	my $grp = aio_group sub { print "finished\n" };
		892	limit $grp 4;
		893	feed $grp sub {
		894	my $file = pop @files
		895	or return;
		896
		897	add $grp aio_stat $file, sub { ... };
		898	};
		899
		900	=item limit $grp $num
		901
		902	Sets the feeder limit for the group: The feeder will be called whenever
		903	the group contains less than this many requests.
		904
		905	Setting the limit to C<0> will pause the feeding process.
		906
		907	=back
		908
403	=head2 SUPPORT FUNCTIONS	909	=head2 SUPPORT FUNCTIONS
		910
		911	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
404		912
405	=over 4	913	=over 4
406		914
407	=item $fileno = IO::AIO::poll_fileno	915	=item $fileno = IO::AIO::poll_fileno
408		916
…		…
413		921
414	See C<poll_cb> for an example.	922	See C<poll_cb> for an example.
415		923
416	=item IO::AIO::poll_cb	924	=item IO::AIO::poll_cb
417		925
418	Process all outstanding events on the result pipe. You have to call this	926	Process some outstanding events on the result pipe. You have to call this
419	regularly. Returns the number of events processed. Returns immediately	927	regularly. Returns the number of events processed. Returns immediately
420	when no events are outstanding.	928	when no events are outstanding. The amount of events processed depends on
		929	the settings of C<IO::AIO::max_poll_req> and C<IO::AIO::max_poll_time>.
		930
		931	If not all requests were processed for whatever reason, the filehandle
		932	will still be ready when C<poll_cb> returns.
421		933
422	Example: Install an Event watcher that automatically calls	934	Example: Install an Event watcher that automatically calls
423	IO::AIO::poll_cb with high priority:	935	IO::AIO::poll_cb with high priority:
424		936
425	Event->io (fd => IO::AIO::poll_fileno,	937	Event->io (fd => IO::AIO::poll_fileno,
426	poll => 'r', async => 1,	938	poll => 'r', async => 1,
427	cb => \&IO::AIO::poll_cb);	939	cb => \&IO::AIO::poll_cb);
428		940
		941	=item IO::AIO::max_poll_reqs $nreqs
		942
		943	=item IO::AIO::max_poll_time $seconds
		944
		945	These set the maximum number of requests (default C<0>, meaning infinity)
		946	that are being processed by C<IO::AIO::poll_cb> in one call, respectively
		947	the maximum amount of time (default C<0>, meaning infinity) spent in
		948	C<IO::AIO::poll_cb> to process requests (more correctly the mininum amount
		949	of time C<poll_cb> is allowed to use).
		950
		951	Setting C<max_poll_time> to a non-zero value creates an overhead of one
		952	syscall per request processed, which is not normally a problem unless your
		953	callbacks are really really fast or your OS is really really slow (I am
		954	not mentioning Solaris here). Using C<max_poll_reqs> incurs no overhead.
		955
		956	Setting these is useful if you want to ensure some level of
		957	interactiveness when perl is not fast enough to process all requests in
		958	time.
		959
		960	For interactive programs, values such as C<0.01> to C<0.1> should be fine.
		961
		962	Example: Install an Event watcher that automatically calls
		963	IO::AIO::poll_cb with low priority, to ensure that other parts of the
		964	program get the CPU sometimes even under high AIO load.
		965
		966	# try not to spend much more than 0.1s in poll_cb
		967	IO::AIO::max_poll_time 0.1;
		968
		969	# use a low priority so other tasks have priority
		970	Event->io (fd => IO::AIO::poll_fileno,
		971	poll => 'r', nice => 1,
		972	cb => &IO::AIO::poll_cb);
		973
429	=item IO::AIO::poll_wait	974	=item IO::AIO::poll_wait
430		975
431	Wait till the result filehandle becomes ready for reading (simply does a	976	Wait till the result filehandle becomes ready for reading (simply does a
432	C<select> on the filehandle. This is useful if you want to synchronously wait	977	C<select> on the filehandle. This is useful if you want to synchronously
433	for some requests to finish).	978	wait for some requests to finish).
434		979
435	See C<nreqs> for an example.	980	See C<nreqs> for an example.
436		981
		982	=item IO::AIO::poll
		983
		984	Waits until some requests have been handled.
		985
		986	Strictly equivalent to:
		987
		988	IO::AIO::poll_wait, IO::AIO::poll_cb
		989	if IO::AIO::nreqs;
		990
437	=item IO::AIO::nreqs	991	=item IO::AIO::flush
438		992
439	Returns the number of requests currently outstanding (i.e. for which their	993	Wait till all outstanding AIO requests have been handled.
440	callback has not been invoked yet).
441		994
442	Example: wait till there are no outstanding requests anymore:	995	Strictly equivalent to:
443		996
444	IO::AIO::poll_wait, IO::AIO::poll_cb	997	IO::AIO::poll_wait, IO::AIO::poll_cb
445	while IO::AIO::nreqs;	998	while IO::AIO::nreqs;
446		999
447	=item IO::AIO::flush	1000	=head3 CONTROLLING THE NUMBER OF THREADS
448
449	Wait till all outstanding AIO requests have been handled.
450
451	Strictly equivalent to:
452
453	IO::AIO::poll_wait, IO::AIO::poll_cb
454	while IO::AIO::nreqs;
455
456	=item IO::AIO::poll
457
458	Waits until some requests have been handled.
459
460	Strictly equivalent to:
461
462	IO::AIO::poll_wait, IO::AIO::poll_cb
463	if IO::AIO::nreqs;
464		1001
465	=item IO::AIO::min_parallel $nthreads	1002	=item IO::AIO::min_parallel $nthreads
466		1003
467	Set the minimum number of AIO threads to C<$nthreads>. The current default	1004	Set the minimum number of AIO threads to C<$nthreads>. The current
468	is C<4>, which means four asynchronous operations can be done at one time	1005	default is C<8>, which means eight asynchronous operations can execute
469	(the number of outstanding operations, however, is unlimited).	1006	concurrently at any one time (the number of outstanding requests,
		1007	however, is unlimited).
470		1008
471	IO::AIO starts threads only on demand, when an AIO request is queued and	1009	IO::AIO starts threads only on demand, when an AIO request is queued and
472	no free thread exists.	1010	no free thread exists. Please note that queueing up a hundred requests can
		1011	create demand for a hundred threads, even if it turns out that everything
		1012	is in the cache and could have been processed faster by a single thread.
473		1013
474	It is recommended to keep the number of threads low, as some Linux	1014	It is recommended to keep the number of threads relatively low, as some
475	kernel versions will scale negatively with the number of threads (higher	1015	Linux kernel versions will scale negatively with the number of threads
476	parallelity => MUCH higher latency). With current Linux 2.6 versions, 4-32	1016	(higher parallelity => MUCH higher latency). With current Linux 2.6
477	threads should be fine.	1017	versions, 4-32 threads should be fine.
478		1018
479	Under most circumstances you don't need to call this function, as the	1019	Under most circumstances you don't need to call this function, as the
480	module selects a default that is suitable for low to moderate load.	1020	module selects a default that is suitable for low to moderate load.
481		1021
482	=item IO::AIO::max_parallel $nthreads	1022	=item IO::AIO::max_parallel $nthreads
…		…
491	This module automatically runs C<max_parallel 0> at program end, to ensure	1031	This module automatically runs C<max_parallel 0> at program end, to ensure
492	that all threads are killed and that there are no outstanding requests.	1032	that all threads are killed and that there are no outstanding requests.
493		1033
494	Under normal circumstances you don't need to call this function.	1034	Under normal circumstances you don't need to call this function.
495		1035
		1036	=item IO::AIO::max_idle $nthreads
		1037
		1038	Limit the number of threads (default: 4) that are allowed to idle (i.e.,
		1039	threads that did not get a request to process within 10 seconds). That
		1040	means if a thread becomes idle while C<$nthreads> other threads are also
		1041	idle, it will free its resources and exit.
		1042
		1043	This is useful when you allow a large number of threads (e.g. 100 or 1000)
		1044	to allow for extremely high load situations, but want to free resources
		1045	under normal circumstances (1000 threads can easily consume 30MB of RAM).
		1046
		1047	The default is probably ok in most situations, especially if thread
		1048	creation is fast. If thread creation is very slow on your system you might
		1049	want to use larger values.
		1050
496	=item $oldnreqs = IO::AIO::max_outstanding $nreqs	1051	=item $oldmaxreqs = IO::AIO::max_outstanding $maxreqs
		1052
		1053	This is a very bad function to use in interactive programs because it
		1054	blocks, and a bad way to reduce concurrency because it is inexact: Better
		1055	use an C<aio_group> together with a feed callback.
497		1056
498	Sets the maximum number of outstanding requests to C<$nreqs>. If you	1057	Sets the maximum number of outstanding requests to C<$nreqs>. If you
499	try to queue up more than this number of requests, the caller will block until	1058	to queue up more than this number of requests, the next call to the
500	some requests have been handled.	1059	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
		1060	function will block until the limit is no longer exceeded.
501		1061
502	The default is very large, so normally there is no practical limit. If you	1062	The default value is very large, so there is no practical limit on the
503	queue up many requests in a loop it often improves speed if you set	1063	number of outstanding requests.
504	this to a relatively low number, such as C<100>.
505		1064
506	Under normal circumstances you don't need to call this function.	1065	You can still queue as many requests as you want. Therefore,
		1066	C<max_oustsanding> is mainly useful in simple scripts (with low values) or
		1067	as a stop gap to shield against fatal memory overflow (with large values).
		1068
		1069	=head3 STATISTICAL INFORMATION
		1070
		1071	=item IO::AIO::nreqs
		1072
		1073	Returns the number of requests currently in the ready, execute or pending
		1074	states (i.e. for which their callback has not been invoked yet).
		1075
		1076	Example: wait till there are no outstanding requests anymore:
		1077
		1078	IO::AIO::poll_wait, IO::AIO::poll_cb
		1079	while IO::AIO::nreqs;
		1080
		1081	=item IO::AIO::nready
		1082
		1083	Returns the number of requests currently in the ready state (not yet
		1084	executed).
		1085
		1086	=item IO::AIO::npending
		1087
		1088	Returns the number of requests currently in the pending state (executed,
		1089	but not yet processed by poll_cb).
507		1090
508	=back	1091	=back
509		1092
510	=cut	1093	=cut
511		1094
…		…
523	or return undef;	1106	or return undef;
524		1107
525	*$sym	1108	*$sym
526	}	1109	}
527		1110
528	min_parallel 4;	1111	min_parallel 8;
529		1112
530	END {	1113	END {
531	max_parallel 0;	1114	min_parallel 1;
532	}	1115	flush;
		1116	};
533		1117
534	1;	1118	1;
535		1119
536	=head2 FORK BEHAVIOUR	1120	=head2 FORK BEHAVIOUR
		1121
		1122	This module should do "the right thing" when the process using it forks:
537		1123
538	Before the fork, IO::AIO enters a quiescent state where no requests	1124	Before the fork, IO::AIO enters a quiescent state where no requests
539	can be added in other threads and no results will be processed. After	1125	can be added in other threads and no results will be processed. After
540	the fork the parent simply leaves the quiescent state and continues	1126	the fork the parent simply leaves the quiescent state and continues
541	request/result processing, while the child clears the request/result	1127	request/result processing, while the child frees the request/result queue
542	queue (so the requests started before the fork will only be handled in	1128	(so that the requests started before the fork will only be handled in the
543	the parent). Threats will be started on demand until the limit ste in the	1129	parent). Threads will be started on demand until the limit set in the
544	parent process has been reached again.	1130	parent process has been reached again.
545		1131
		1132	In short: the parent will, after a short pause, continue as if fork had
		1133	not been called, while the child will act as if IO::AIO has not been used
		1134	yet.
		1135
		1136	=head2 MEMORY USAGE
		1137
		1138	Per-request usage:
		1139
		1140	Each aio request uses - depending on your architecture - around 100-200
		1141	bytes of memory. In addition, stat requests need a stat buffer (possibly
		1142	a few hundred bytes), readdir requires a result buffer and so on. Perl
		1143	scalars and other data passed into aio requests will also be locked and
		1144	will consume memory till the request has entered the done state.
		1145
		1146	This is now awfully much, so queuing lots of requests is not usually a
		1147	problem.
		1148
		1149	Per-thread usage:
		1150
		1151	In the execution phase, some aio requests require more memory for
		1152	temporary buffers, and each thread requires a stack and other data
		1153	structures (usually around 16k-128k, depending on the OS).
		1154
		1155	=head1 KNOWN BUGS
		1156
		1157	Known bugs will be fixed in the next release.
		1158
546	=head1 SEE ALSO	1159	=head1 SEE ALSO
547		1160
548	L<Coro>, L<Linux::AIO>.	1161	L<Coro::AIO>.
549		1162
550	=head1 AUTHOR	1163	=head1 AUTHOR
551		1164
552	Marc Lehmann <schmorp@schmorp.de>	1165	Marc Lehmann <schmorp@schmorp.de>
553	http://home.schmorp.de/	1166	http://home.schmorp.de/

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Comparing IO-AIO/AIO.pm (file contents): Revision 1.49 by root, Wed Mar 1 23:56:54 2006 UTC vs. Revision 1.91 by root, Mon Oct 30 23:30:29 2006 UTC

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Comparing IO-AIO/AIO.pm (file contents):
Revision 1.49 by root, Wed Mar 1 23:56:54 2006 UTC vs.
Revision 1.91 by root, Mon Oct 30 23:30:29 2006 UTC