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

Comparing IO-AIO/AIO.pm (file contents):
Revision 1.42 by root, Mon Dec 26 18:15:23 2005 UTC vs.
Revision 1.86 by root, Sat Oct 28 23:32:29 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 this works on all types of file descriptors (for example sockets),
		67	using these functions on file descriptors that support nonblocking
		68	operation (again, sockets, pipes etc.) is very inefficient. Use an event
		69	loop for that (such as the L<Event\|Event> module): IO::AIO will naturally
		70	fit into such an event loop itself.
		71
47	Currently, a number of threads are started that execute your read/writes	72	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	73	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	74	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	75	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	76	functions available on many operating systems. However, they are often
52	not well-supported (Linux doesn't allow them on normal files currently,	77	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	78	files currently, for example), and they would only support aio_read and
54	remaining functionality would have to be implemented using threads anyway.	79	aio_write, so the remaining functionality would have to be implemented
		80	using threads anyway.
55		81
56	Although the module will work with in the presence of other threads, it is	82	Although the module will work with in the presence of other (Perl-)
57	currently not reentrant, so use appropriate locking yourself, always call	83	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	84	locking yourself, always call C<poll_cb> from within the same thread, or
59	C<aio_> functions) recursively.	85	never call C<poll_cb> (or other C<aio_> functions) recursively.
		86
		87	=head2 EXAMPLE
		88
		89	This is a simple example that uses the Event module and loads
		90	F</etc/passwd> asynchronously:
		91
		92	use Fcntl;
		93	use Event;
		94	use IO::AIO;
		95
		96	# register the IO::AIO callback with Event
		97	Event->io (fd => IO::AIO::poll_fileno,
		98	poll => 'r',
		99	cb => \&IO::AIO::poll_cb);
		100
		101	# queue the request to open /etc/passwd
		102	aio_open "/etc/passwd", O_RDONLY, 0, sub {
		103	my $fh = $_[0]
		104	or die "error while opening: $!";
		105
		106	# stat'ing filehandles is generally non-blocking
		107	my $size = -s $fh;
		108
		109	# queue a request to read the file
		110	my $contents;
		111	aio_read $fh, 0, $size, $contents, 0, sub {
		112	$_[0] == $size
		113	or die "short read: $!";
		114
		115	close $fh;
		116
		117	# file contents now in $contents
		118	print $contents;
		119
		120	# exit event loop and program
		121	Event::unloop;
		122	};
		123	};
		124
		125	# possibly queue up other requests, or open GUI windows,
		126	# check for sockets etc. etc.
		127
		128	# process events as long as there are some:
		129	Event::loop;
		130
		131	=head1 REQUEST ANATOMY AND LIFETIME
		132
		133	Every C<aio_*> function creates a request. which is a C data structure not
		134	directly visible to Perl.
		135
		136	If called in non-void context, every request function returns a Perl
		137	object representing the request. In void context, nothing is returned,
		138	which saves a bit of memory.
		139
		140	The perl object is a fairly standard ref-to-hash object. The hash contents
		141	are not used by IO::AIO so you are free to store anything you like in it.
		142
		143	During their existance, aio requests travel through the following states,
		144	in order:
		145
		146	=over 4
		147
		148	=item ready
		149
		150	Immediately after a request is created it is put into the ready state,
		151	waiting for a thread to execute it.
		152
		153	=item execute
		154
		155	A thread has accepted the request for processing and is currently
		156	executing it (e.g. blocking in read).
		157
		158	=item pending
		159
		160	The request has been executed and is waiting for result processing.
		161
		162	While request submission and execution is fully asynchronous, result
		163	processing is not and relies on the perl interpreter calling C<poll_cb>
		164	(or another function with the same effect).
		165
		166	=item result
		167
		168	The request results are processed synchronously by C<poll_cb>.
		169
		170	The C<poll_cb> function will process all outstanding aio requests by
		171	calling their callbacks, freeing memory associated with them and managing
		172	any groups they are contained in.
		173
		174	=item done
		175
		176	Request has reached the end of its lifetime and holds no resources anymore
		177	(except possibly for the Perl object, but its connection to the actual
		178	aio request is severed and calling its methods will either do nothing or
		179	result in a runtime error).
60		180
61	=cut	181	=cut
62		182
63	package IO::AIO;	183	package IO::AIO;
64		184
65	no warnings;	185	no warnings;
		186	use strict 'vars';
66		187
67	use base 'Exporter';	188	use base 'Exporter';
68		189
69	use Fcntl ();
70
71	BEGIN {	190	BEGIN {
72	$VERSION = '1.61';	191	our $VERSION = '2.1';
73		192
74	@EXPORT = qw(aio_sendfile aio_read aio_write aio_open aio_close aio_stat	193	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	194	aio_lstat aio_unlink aio_rmdir aio_readdir aio_scandir aio_symlink
76	aio_fsync aio_fdatasync aio_readahead);	195	aio_fsync aio_fdatasync aio_readahead aio_rename aio_link aio_move
77	@EXPORT_OK = qw(poll_fileno poll_cb min_parallel max_parallel	196	aio_copy aio_group aio_nop aio_mknod);
78	max_outstanding nreqs);	197	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
		198	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
		199	min_parallel max_parallel max_idle
		200	nreqs nready npending nthreads
		201	max_poll_time max_poll_reqs);
		202
		203	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';
79		204
80	require XSLoader;	205	require XSLoader;
81	XSLoader::load IO::AIO, $VERSION;	206	XSLoader::load ("IO::AIO", $VERSION);
82	}	207	}
83		208
84	=head1 FUNCTIONS	209	=head1 FUNCTIONS
85		210
86	=head2 AIO FUNCTIONS	211	=head2 AIO FUNCTIONS
…		…
94	syscall has been executed asynchronously.	219	syscall has been executed asynchronously.
95		220
96	All functions expecting a filehandle keep a copy of the filehandle	221	All functions expecting a filehandle keep a copy of the filehandle
97	internally until the request has finished.	222	internally until the request has finished.
98		223
		224	All requests return objects of type L<IO::AIO::REQ> that allow further
		225	manipulation of those requests while they are in-flight.
		226
99	The pathnames you pass to these routines I<must> be absolute and	227	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	228	encoded in byte form. The reason for the former is that at the time the
101	request is being executed, the current working directory could have	229	request is being executed, the current working directory could have
102	changed. Alternatively, you can make sure that you never change the	230	changed. Alternatively, you can make sure that you never change the
103	current working directory.	231	current working directory.
…		…
108	your pathnames to the locale (or other) encoding in effect in the user	236	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)	237	environment, d) use Glib::filename_from_unicode on unicode filenames or e)
110	use something else.	238	use something else.
111		239
112	=over 4	240	=over 4
		241
		242	=item $prev_pri = aioreq_pri [$pri]
		243
		244	Returns the priority value that would be used for the next request and, if
		245	C<$pri> is given, sets the priority for the next aio request.
		246
		247	The default priority is C<0>, the minimum and maximum priorities are C<-4>
		248	and C<4>, respectively. Requests with higher priority will be serviced
		249	first.
		250
		251	The priority will be reset to C<0> after each call to one of the C<aio_*>
		252	functions.
		253
		254	Example: open a file with low priority, then read something from it with
		255	higher priority so the read request is serviced before other low priority
		256	open requests (potentially spamming the cache):
		257
		258	aioreq_pri -3;
		259	aio_open ..., sub {
		260	return unless $_[0];
		261
		262	aioreq_pri -2;
		263	aio_read $_[0], ..., sub {
		264	...
		265	};
		266	};
		267
		268	=item aioreq_nice $pri_adjust
		269
		270	Similar to C<aioreq_pri>, but subtracts the given value from the current
		271	priority, so effects are cumulative.
113		272
114	=item aio_open $pathname, $flags, $mode, $callback->($fh)	273	=item aio_open $pathname, $flags, $mode, $callback->($fh)
115		274
116	Asynchronously open or create a file and call the callback with a newly	275	Asynchronously open or create a file and call the callback with a newly
117	created filehandle for the file.	276	created filehandle for the file.
…		…
232	=item aio_unlink $pathname, $callback->($status)	391	=item aio_unlink $pathname, $callback->($status)
233		392
234	Asynchronously unlink (delete) a file and call the callback with the	393	Asynchronously unlink (delete) a file and call the callback with the
235	result code.	394	result code.
236		395
		396	=item aio_mknod $path, $mode, $dev, $callback->($status)
		397
		398	[EXPERIMENTAL]
		399
		400	Asynchronously create a device node (or fifo). See mknod(2).
		401
		402	The only (POSIX-) portable way of calling this function is:
		403
		404	aio_mknod $path, IO::AIO::S_IFIFO \| $mode, 0, sub { ...
		405
		406	=item aio_link $srcpath, $dstpath, $callback->($status)
		407
		408	Asynchronously create a new link to the existing object at C<$srcpath> at
		409	the path C<$dstpath> and call the callback with the result code.
		410
		411	=item aio_symlink $srcpath, $dstpath, $callback->($status)
		412
		413	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at
		414	the path C<$dstpath> and call the callback with the result code.
		415
		416	=item aio_rename $srcpath, $dstpath, $callback->($status)
		417
		418	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
		419	rename(2) and call the callback with the result code.
		420
237	=item aio_rmdir $pathname, $callback->($status)	421	=item aio_rmdir $pathname, $callback->($status)
238		422
239	Asynchronously rmdir (delete) a directory and call the callback with the	423	Asynchronously rmdir (delete) a directory and call the callback with the
240	result code.	424	result code.
241		425
242	=item aio_readdir $pathname $callback->($entries)	426	=item aio_readdir $pathname, $callback->($entries)
243		427
244	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire	428	Unlike the POSIX call of the same name, C<aio_readdir> reads an entire
245	directory (i.e. opendir + readdir + closedir). The entries will not be	429	directory (i.e. opendir + readdir + closedir). The entries will not be
246	sorted, and will B<NOT> include the C<.> and C<..> entries.	430	sorted, and will B<NOT> include the C<.> and C<..> entries.
247		431
248	The callback a single argument which is either C<undef> or an array-ref	432	The callback a single argument which is either C<undef> or an array-ref
249	with the filenames.	433	with the filenames.
250		434
		435	=item aio_copy $srcpath, $dstpath, $callback->($status)
		436
		437	Try to copy the I<file> (directories not supported as either source or
		438	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		439	the C<0> (error) or C<-1> ok.
		440
		441	This is a composite request that it creates the destination file with
		442	mode 0200 and copies the contents of the source file into it using
		443	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
		444	uid/gid, in that order.
		445
		446	If an error occurs, the partial destination file will be unlinked, if
		447	possible, except when setting atime, mtime, access mode and uid/gid, where
		448	errors are being ignored.
		449
		450	=cut
		451
		452	sub aio_copy($$;$) {
		453	my ($src, $dst, $cb) = @_;
		454
		455	my $pri = aioreq_pri;
		456	my $grp = aio_group $cb;
		457
		458	aioreq_pri $pri;
		459	add $grp aio_open $src, O_RDONLY, 0, sub {
		460	if (my $src_fh = $_[0]) {
		461	my @stat = stat $src_fh;
		462
		463	aioreq_pri $pri;
		464	add $grp aio_open $dst, O_CREAT \| O_WRONLY \| O_TRUNC, 0200, sub {
		465	if (my $dst_fh = $_[0]) {
		466	aioreq_pri $pri;
		467	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
		468	if ($_[0] == $stat[7]) {
		469	$grp->result (0);
		470	close $src_fh;
		471
		472	# those should not normally block. should. should.
		473	utime $stat[8], $stat[9], $dst;
		474	chmod $stat[2] & 07777, $dst_fh;
		475	chown $stat[4], $stat[5], $dst_fh;
		476	close $dst_fh;
		477	} else {
		478	$grp->result (-1);
		479	close $src_fh;
		480	close $dst_fh;
		481
		482	aioreq $pri;
		483	add $grp aio_unlink $dst;
		484	}
		485	};
		486	} else {
		487	$grp->result (-1);
		488	}
		489	},
		490
		491	} else {
		492	$grp->result (-1);
		493	}
		494	};
		495
		496	$grp
		497	}
		498
		499	=item aio_move $srcpath, $dstpath, $callback->($status)
		500
		501	Try to move the I<file> (directories not supported as either source or
		502	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		503	the C<0> (error) or C<-1> ok.
		504
		505	This is a composite request that tries to rename(2) the file first. If
		506	rename files with C<EXDEV>, it copies the file with C<aio_copy> and, if
		507	that is successful, unlinking the C<$srcpath>.
		508
		509	=cut
		510
		511	sub aio_move($$;$) {
		512	my ($src, $dst, $cb) = @_;
		513
		514	my $pri = aioreq_pri;
		515	my $grp = aio_group $cb;
		516
		517	aioreq_pri $pri;
		518	add $grp aio_rename $src, $dst, sub {
		519	if ($_[0] && $! == EXDEV) {
		520	aioreq_pri $pri;
		521	add $grp aio_copy $src, $dst, sub {
		522	$grp->result ($_[0]);
		523
		524	if (!$_[0]) {
		525	aioreq_pri $pri;
		526	add $grp aio_unlink $src;
		527	}
		528	};
		529	} else {
		530	$grp->result ($_[0]);
		531	}
		532	};
		533
		534	$grp
		535	}
		536
251	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	537	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
252		538
253	Scans a directory (similar to C<aio_readdir>) and tries to separate the	539	Scans a directory (similar to C<aio_readdir>) but additionally tries to
254	entries of directory C<$path> into two sets of names, ones you can recurse	540	efficiently separate the entries of directory C<$path> into two sets of
255	into (directories), and ones you cannot recurse into (everything else).	541	names, directories you can recurse into (directories), and ones you cannot
		542	recurse into (everything else, including symlinks to directories).
256		543
257	C<aio_scandir> is a composite request that consists of many	544	C<aio_scandir> is a composite request that creates of many sub requests_
258	aio-primitives. C<$maxreq> specifies the maximum number of outstanding	545	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	546	this function generates. If it is C<< <= 0 >>, then a suitable default
260	suitable default will be chosen (currently 8).	547	will be chosen (currently 4).
261		548
262	On error, the callback is called without arguments, otherwise it receives	549	On error, the callback is called without arguments, otherwise it receives
263	two array-refs with path-relative entry names.	550	two array-refs with path-relative entry names.
264		551
265	Example:	552	Example:
…		…
273	Implementation notes.	560	Implementation notes.
274		561
275	The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can.	562	The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can.
276		563
277	After reading the directory, the modification time, size etc. of the	564	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	565	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	566	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	567	entries are directories (if >= 2). Otherwise, no knowledge of the number
281	assumed.	568	of subdirectories will be assumed.
282		569
283	Then entires will be sorted into likely directories (everything without a	570	Then entries will be sorted into likely directories (everything without
284	non-initial dot) and likely non-directories (everything else). Then every	571	a non-initial dot currently) and likely non-directories (everything
285	entry + C</.> will be C<stat>'ed, likely directories first. This is often	572	else). Then every entry plus an appended C</.> will be C<stat>'ed,
		573	likely directories first. If that succeeds, it assumes that the entry
		574	is a directory or a symlink to directory (which will be checked
		575	seperately). This is often faster than stat'ing the entry itself because
286	faster because filesystems might detect the type of the entry without	576	filesystems might detect the type of the entry without reading the inode
287	reading the inode data (e.g. ext2s filetype feature). If that succeeds,	577	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		578
291	If the known number of directories has been reached, the rest of the	579	If the known number of directories (link count - 2) has been reached, the
292	entries is assumed to be non-directories.	580	rest of the entries is assumed to be non-directories.
		581
		582	This only works with certainty on POSIX (= UNIX) filesystems, which
		583	fortunately are the vast majority of filesystems around.
		584
		585	It will also likely work on non-POSIX filesystems with reduced efficiency
		586	as those tend to return 0 or 1 as link counts, which disables the
		587	directory counting heuristic.
293		588
294	=cut	589	=cut
295		590
296	sub aio_scandir($$$) {	591	sub aio_scandir($$$) {
297	my ($path, $maxreq, $cb) = @_;	592	my ($path, $maxreq, $cb) = @_;
298		593
		594	my $pri = aioreq_pri;
		595
		596	my $grp = aio_group $cb;
		597
299	$maxreq = 8 if $maxreq <= 0;	598	$maxreq = 4 if $maxreq <= 0;
300		599
301	# stat once	600	# stat once
		601	aioreq_pri $pri;
302	aio_stat $path, sub {	602	add $grp aio_stat $path, sub {
303	$cb->() if $_[0];	603	return $grp->result () if $_[0];
		604	my $now = time;
304	my $hash1 = join ":", (stat _)[0,1,3,7,9];	605	my $hash1 = join ":", (stat _)[0,1,3,7,9];
305		606
306	# read the directory entries	607	# read the directory entries
		608	aioreq_pri $pri;
307	aio_readdir $path, sub {	609	add $grp aio_readdir $path, sub {
308	my $entries = shift	610	my $entries = shift
309	or return $cb->();	611	or return $grp->result ();
310		612
311	# stat the dir another time	613	# stat the dir another time
		614	aioreq_pri $pri;
312	aio_stat $path, sub {	615	add $grp aio_stat $path, sub {
313	my $hash2 = join ":", (stat _)[0,1,3,7,9];	616	my $hash2 = join ":", (stat _)[0,1,3,7,9];
314		617
315	my $ndirs;	618	my $ndirs;
316		619
317	# take the slow route if anything looks fishy	620	# take the slow route if anything looks fishy
318	if ($hash1 ne $hash2) {	621	if ($hash1 ne $hash2 or (stat _)[9] == $now) {
319	$ndirs = -1;	622	$ndirs = -1;
320	} else {	623	} else {
321	# if nlink == 2, we are finished	624	# if nlink == 2, we are finished
322	# on non-posix-fs's, we rely on nlink < 2	625	# on non-posix-fs's, we rely on nlink < 2
323	$ndirs = (stat _)[3] - 2	626	$ndirs = (stat _)[3] - 2
324	or $cb->([], $entries);	627	or return $grp->result ([], $entries);
325	}	628	}
326		629
327	# sort into likely dirs and likely nondirs	630	# sort into likely dirs and likely nondirs
328	# dirs == files without ".", short entries first	631	# dirs == files without ".", short entries first
329	$entries = [map $_->[0],	632	$entries = [map $_->[0],
…		…
331	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],	634	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
332	@$entries];	635	@$entries];
333		636
334	my (@dirs, @nondirs);	637	my (@dirs, @nondirs);
335		638
336	my ($statcb, $schedcb);	639	my $statgrp = add $grp aio_group sub {
337	my $nreq = 0;	640	$grp->result (\@dirs, \@nondirs);
		641	};
338		642
339	$schedcb = sub {	643	limit $statgrp $maxreq;
340	if (@$entries) {	644	feed $statgrp sub {
341	if ($nreq < $maxreq) {	645	return unless @$entries;
342	my $ent = pop @$entries;	646	my $entry = pop @$entries;
		647
		648	aioreq_pri $pri;
		649	add $statgrp aio_stat "$path/$entry/.", sub {
		650	if ($_[0] < 0) {
		651	push @nondirs, $entry;
		652	} else {
		653	# need to check for real directory
		654	aioreq_pri $pri;
		655	add $statgrp aio_lstat "$path/$entry", sub {
		656	if (-d _) {
		657	push @dirs, $entry;
		658
		659	unless (--$ndirs) {
		660	push @nondirs, @$entries;
		661	feed $statgrp;
		662	}
		663	} else {
		664	push @nondirs, $entry;
		665	}
343	$nreq++;	666	}
344	aio_stat "$path/$ent/.", sub { $statcb->($_[0], $ent) };
345	}	667	}
346	} elsif (!$nreq) {
347	# finished
348	undef $statcb;
349	undef $schedcb;
350	$cb->(\@dirs, \@nondirs);
351	undef $cb;
352	}	668	};
353	};	669	};
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	};	670	};
384	};	671	};
385	};	672	};
		673
		674	$grp
386	}	675	}
387		676
388	=item aio_fsync $fh, $callback->($status)	677	=item aio_fsync $fh, $callback->($status)
389		678
390	Asynchronously call fsync on the given filehandle and call the callback	679	Asynchronously call fsync on the given filehandle and call the callback
…		…
396	callback with the fdatasync result code.	685	callback with the fdatasync result code.
397		686
398	If this call isn't available because your OS lacks it or it couldn't be	687	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.	688	detected, it will be emulated by calling C<fsync> instead.
400		689
		690	=item aio_group $callback->(...)
		691
		692	This is a very special aio request: Instead of doing something, it is a
		693	container for other aio requests, which is useful if you want to bundle
		694	many requests into a single, composite, request with a definite callback
		695	and the ability to cancel the whole request with its subrequests.
		696
		697	Returns an object of class L<IO::AIO::GRP>. See its documentation below
		698	for more info.
		699
		700	Example:
		701
		702	my $grp = aio_group sub {
		703	print "all stats done\n";
		704	};
		705
		706	add $grp
		707	(aio_stat ...),
		708	(aio_stat ...),
		709	...;
		710
		711	=item aio_nop $callback->()
		712
		713	This is a special request - it does nothing in itself and is only used for
		714	side effects, such as when you want to add a dummy request to a group so
		715	that finishing the requests in the group depends on executing the given
		716	code.
		717
		718	While this request does nothing, it still goes through the execution
		719	phase and still requires a worker thread. Thus, the callback will not
		720	be executed immediately but only after other requests in the queue have
		721	entered their execution phase. This can be used to measure request
		722	latency.
		723
		724	=item IO::AIO::aio_busy $fractional_seconds, $callback->() NOT EXPORTED
		725
		726	Mainly used for debugging and benchmarking, this aio request puts one of
		727	the request workers to sleep for the given time.
		728
		729	While it is theoretically handy to have simple I/O scheduling requests
		730	like sleep and file handle readable/writable, the overhead this creates is
		731	immense (it blocks a thread for a long time) so do not use this function
		732	except to put your application under artificial I/O pressure.
		733
401	=back	734	=back
402		735
		736	=head2 IO::AIO::REQ CLASS
		737
		738	All non-aggregate C<aio_*> functions return an object of this class when
		739	called in non-void context.
		740
		741	=over 4
		742
		743	=item cancel $req
		744
		745	Cancels the request, if possible. Has the effect of skipping execution
		746	when entering the B<execute> state and skipping calling the callback when
		747	entering the the B<result> state, but will leave the request otherwise
		748	untouched. That means that requests that currently execute will not be
		749	stopped and resources held by the request will not be freed prematurely.
		750
		751	=item cb $req $callback->(...)
		752
		753	Replace (or simply set) the callback registered to the request.
		754
		755	=back
		756
		757	=head2 IO::AIO::GRP CLASS
		758
		759	This class is a subclass of L<IO::AIO::REQ>, so all its methods apply to
		760	objects of this class, too.
		761
		762	A IO::AIO::GRP object is a special request that can contain multiple other
		763	aio requests.
		764
		765	You create one by calling the C<aio_group> constructing function with a
		766	callback that will be called when all contained requests have entered the
		767	C<done> state:
		768
		769	my $grp = aio_group sub {
		770	print "all requests are done\n";
		771	};
		772
		773	You add requests by calling the C<add> method with one or more
		774	C<IO::AIO::REQ> objects:
		775
		776	$grp->add (aio_unlink "...");
		777
		778	add $grp aio_stat "...", sub {
		779	$_[0] or return $grp->result ("error");
		780
		781	# add another request dynamically, if first succeeded
		782	add $grp aio_open "...", sub {
		783	$grp->result ("ok");
		784	};
		785	};
		786
		787	This makes it very easy to create composite requests (see the source of
		788	C<aio_move> for an application) that work and feel like simple requests.
		789
		790	=over 4
		791
		792	=item * The IO::AIO::GRP objects will be cleaned up during calls to
		793	C<IO::AIO::poll_cb>, just like any other request.
		794
		795	=item * They can be canceled like any other request. Canceling will cancel not
		796	only the request itself, but also all requests it contains.
		797
		798	=item * They can also can also be added to other IO::AIO::GRP objects.
		799
		800	=item * You must not add requests to a group from within the group callback (or
		801	any later time).
		802
		803	=back
		804
		805	Their lifetime, simplified, looks like this: when they are empty, they
		806	will finish very quickly. If they contain only requests that are in the
		807	C<done> state, they will also finish. Otherwise they will continue to
		808	exist.
		809
		810	That means after creating a group you have some time to add requests. And
		811	in the callbacks of those requests, you can add further requests to the
		812	group. And only when all those requests have finished will the the group
		813	itself finish.
		814
		815	=over 4
		816
		817	=item add $grp ...
		818
		819	=item $grp->add (...)
		820
		821	Add one or more requests to the group. Any type of L<IO::AIO::REQ> can
		822	be added, including other groups, as long as you do not create circular
		823	dependencies.
		824
		825	Returns all its arguments.
		826
		827	=item $grp->cancel_subs
		828
		829	Cancel all subrequests and clears any feeder, but not the group request
		830	itself. Useful when you queued a lot of events but got a result early.
		831
		832	=item $grp->result (...)
		833
		834	Set the result value(s) that will be passed to the group callback when all
		835	subrequests have finished and set thre groups errno to the current value
		836	of errno (just like calling C<errno> without an error number). By default,
		837	no argument will be passed and errno is zero.
		838
		839	=item $grp->errno ([$errno])
		840
		841	Sets the group errno value to C<$errno>, or the current value of errno
		842	when the argument is missing.
		843
		844	Every aio request has an associated errno value that is restored when
		845	the callback is invoked. This method lets you change this value from its
		846	default (0).
		847
		848	Calling C<result> will also set errno, so make sure you either set C<$!>
		849	before the call to C<result>, or call c<errno> after it.
		850
		851	=item feed $grp $callback->($grp)
		852
		853	Sets a feeder/generator on this group: every group can have an attached
		854	generator that generates requests if idle. The idea behind this is that,
		855	although you could just queue as many requests as you want in a group,
		856	this might starve other requests for a potentially long time. For
		857	example, C<aio_scandir> might generate hundreds of thousands C<aio_stat>
		858	requests, delaying any later requests for a long time.
		859
		860	To avoid this, and allow incremental generation of requests, you can
		861	instead a group and set a feeder on it that generates those requests. The
		862	feed callback will be called whenever there are few enough (see C<limit>,
		863	below) requests active in the group itself and is expected to queue more
		864	requests.
		865
		866	The feed callback can queue as many requests as it likes (i.e. C<add> does
		867	not impose any limits).
		868
		869	If the feed does not queue more requests when called, it will be
		870	automatically removed from the group.
		871
		872	If the feed limit is C<0>, it will be set to C<2> automatically.
		873
		874	Example:
		875
		876	# stat all files in @files, but only ever use four aio requests concurrently:
		877
		878	my $grp = aio_group sub { print "finished\n" };
		879	limit $grp 4;
		880	feed $grp sub {
		881	my $file = pop @files
		882	or return;
		883
		884	add $grp aio_stat $file, sub { ... };
		885	};
		886
		887	=item limit $grp $num
		888
		889	Sets the feeder limit for the group: The feeder will be called whenever
		890	the group contains less than this many requests.
		891
		892	Setting the limit to C<0> will pause the feeding process.
		893
		894	=back
		895
403	=head2 SUPPORT FUNCTIONS	896	=head2 SUPPORT FUNCTIONS
		897
		898	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
404		899
405	=over 4	900	=over 4
406		901
407	=item $fileno = IO::AIO::poll_fileno	902	=item $fileno = IO::AIO::poll_fileno
408		903
…		…
413		908
414	See C<poll_cb> for an example.	909	See C<poll_cb> for an example.
415		910
416	=item IO::AIO::poll_cb	911	=item IO::AIO::poll_cb
417		912
418	Process all outstanding events on the result pipe. You have to call this	913	Process some outstanding events on the result pipe. You have to call this
419	regularly. Returns the number of events processed. Returns immediately	914	regularly. Returns the number of events processed. Returns immediately
420	when no events are outstanding.	915	when no events are outstanding. The amount of events processed depends on
		916	the settings of C<IO::AIO::max_poll_req> and C<IO::AIO::max_poll_time>.
		917
		918	If not all requests were processed for whatever reason, the filehandle
		919	will still be ready when C<poll_cb> returns.
421		920
422	Example: Install an Event watcher that automatically calls	921	Example: Install an Event watcher that automatically calls
423	IO::AIO::poll_cb with high priority:	922	IO::AIO::poll_cb with high priority:
424		923
425	Event->io (fd => IO::AIO::poll_fileno,	924	Event->io (fd => IO::AIO::poll_fileno,
426	poll => 'r', async => 1,	925	poll => 'r', async => 1,
427	cb => \&IO::AIO::poll_cb);	926	cb => \&IO::AIO::poll_cb);
428		927
		928	=item IO::AIO::max_poll_reqs $nreqs
		929
		930	=item IO::AIO::max_poll_time $seconds
		931
		932	These set the maximum number of requests (default C<0>, meaning infinity)
		933	that are being processed by C<IO::AIO::poll_cb> in one call, respectively
		934	the maximum amount of time (default C<0>, meaning infinity) spent in
		935	C<IO::AIO::poll_cb> to process requests (more correctly the mininum amount
		936	of time C<poll_cb> is allowed to use).
		937
		938	Setting these is useful if you want to ensure some level of
		939	interactiveness when perl is not fast enough to process all requests in
		940	time.
		941
		942	For interactive programs, values such as C<0.01> to C<0.1> should be fine.
		943
		944	Example: Install an Event watcher that automatically calls
		945	IO::AIO::poll_some with low priority, to ensure that other parts of the
		946	program get the CPU sometimes even under high AIO load.
		947
		948	# try not to spend much more than 0.1s in poll_cb
		949	IO::AIO::max_poll_time 0.1;
		950
		951	# use a low priority so other tasks have priority
		952	Event->io (fd => IO::AIO::poll_fileno,
		953	poll => 'r', nice => 1,
		954	cb => &IO::AIO::poll_cb);
		955
429	=item IO::AIO::poll_wait	956	=item IO::AIO::poll_wait
430		957
431	Wait till the result filehandle becomes ready for reading (simply does a	958	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	959	C<select> on the filehandle. This is useful if you want to synchronously
433	for some requests to finish).	960	wait for some requests to finish).
434		961
435	See C<nreqs> for an example.	962	See C<nreqs> for an example.
436		963
		964	=item IO::AIO::poll
		965
		966	Waits until some requests have been handled.
		967
		968	Strictly equivalent to:
		969
		970	IO::AIO::poll_wait, IO::AIO::poll_cb
		971	if IO::AIO::nreqs;
		972
437	=item IO::AIO::nreqs	973	=item IO::AIO::flush
438		974
439	Returns the number of requests currently outstanding (i.e. for which their	975	Wait till all outstanding AIO requests have been handled.
440	callback has not been invoked yet).
441		976
442	Example: wait till there are no outstanding requests anymore:	977	Strictly equivalent to:
443		978
444	IO::AIO::poll_wait, IO::AIO::poll_cb	979	IO::AIO::poll_wait, IO::AIO::poll_cb
445	while IO::AIO::nreqs;	980	while IO::AIO::nreqs;
446		981
447	=item IO::AIO::flush	982	=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		983
465	=item IO::AIO::min_parallel $nthreads	984	=item IO::AIO::min_parallel $nthreads
466		985
467	Set the minimum number of AIO threads to C<$nthreads>. The current default	986	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	987	default is C<8>, which means eight asynchronous operations can execute
469	(the number of outstanding operations, however, is unlimited).	988	concurrently at any one time (the number of outstanding requests,
		989	however, is unlimited).
470		990
471	IO::AIO starts threads only on demand, when an AIO request is queued and	991	IO::AIO starts threads only on demand, when an AIO request is queued and
472	no free thread exists.	992	no free thread exists. Please note that queueing up a hundred requests can
		993	create demand for a hundred threads, even if it turns out that everything
		994	is in the cache and could have been processed faster by a single thread.
473		995
474	It is recommended to keep the number of threads low, as some Linux	996	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	997	Linux kernel versions will scale negatively with the number of threads
476	parallelity => MUCH higher latency). With current Linux 2.6 versions, 4-32	998	(higher parallelity => MUCH higher latency). With current Linux 2.6
477	threads should be fine.	999	versions, 4-32 threads should be fine.
478		1000
479	Under most circumstances you don't need to call this function, as the	1001	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.	1002	module selects a default that is suitable for low to moderate load.
481		1003
482	=item IO::AIO::max_parallel $nthreads	1004	=item IO::AIO::max_parallel $nthreads
…		…
491	This module automatically runs C<max_parallel 0> at program end, to ensure	1013	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.	1014	that all threads are killed and that there are no outstanding requests.
493		1015
494	Under normal circumstances you don't need to call this function.	1016	Under normal circumstances you don't need to call this function.
495		1017
		1018	=item IO::AIO::max_idle $nthreads
		1019
		1020	Limit the number of threads (default: 4) that are allowed to idle (i.e.,
		1021	threads that did not get a request to process within 10 seconds). That
		1022	means if a thread becomes idle while C<$nthreads> other threads are also
		1023	idle, it will free its resources and exit.
		1024
		1025	This is useful when you allow a large number of threads (e.g. 100 or 1000)
		1026	to allow for extremely high load situations, but want to free resources
		1027	under normal circumstances (1000 threads can easily consume 30MB of RAM).
		1028
		1029	The default is probably ok in most situations, especially if thread
		1030	creation is fast. If thread creation is very slow on your system you might
		1031	want to use larger values.
		1032
496	=item $oldnreqs = IO::AIO::max_outstanding $nreqs	1033	=item $oldmaxreqs = IO::AIO::max_outstanding $maxreqs
		1034
		1035	This is a very bad function to use in interactive programs because it
		1036	blocks, and a bad way to reduce concurrency because it is inexact: Better
		1037	use an C<aio_group> together with a feed callback.
497		1038
498	Sets the maximum number of outstanding requests to C<$nreqs>. If you	1039	Sets the maximum number of outstanding requests to C<$nreqs>. If you
499	try to queue up more than this number of requests, the caller will block until	1040	to queue up more than this number of requests, the next call to the
500	some requests have been handled.	1041	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
		1042	function will block until the limit is no longer exceeded.
501		1043
502	The default is very large, so normally there is no practical limit. If you	1044	The default value is very large, so there is no practical limit on the
503	queue up many requests in a loop it often improves speed if you set	1045	number of outstanding requests.
504	this to a relatively low number, such as C<100>.
505		1046
506	Under normal circumstances you don't need to call this function.	1047	You can still queue as many requests as you want. Therefore,
		1048	C<max_oustsanding> is mainly useful in simple scripts (with low values) or
		1049	as a stop gap to shield against fatal memory overflow (with large values).
		1050
		1051	=head3 STATISTICAL INFORMATION
		1052
		1053	=item IO::AIO::nreqs
		1054
		1055	Returns the number of requests currently in the ready, execute or pending
		1056	states (i.e. for which their callback has not been invoked yet).
		1057
		1058	Example: wait till there are no outstanding requests anymore:
		1059
		1060	IO::AIO::poll_wait, IO::AIO::poll_cb
		1061	while IO::AIO::nreqs;
		1062
		1063	=item IO::AIO::nready
		1064
		1065	Returns the number of requests currently in the ready state (not yet
		1066	executed).
		1067
		1068	=item IO::AIO::npending
		1069
		1070	Returns the number of requests currently in the pending state (executed,
		1071	but not yet processed by poll_cb).
507		1072
508	=back	1073	=back
509		1074
510	=cut	1075	=cut
511		1076
…		…
523	or return undef;	1088	or return undef;
524		1089
525	*$sym	1090	*$sym
526	}	1091	}
527		1092
528	min_parallel 4;	1093	min_parallel 8;
529		1094
530	END {	1095	END {
531	max_parallel 0;	1096	min_parallel 1;
532	}	1097	flush;
		1098	};
533		1099
534	1;	1100	1;
535		1101
536	=head2 FORK BEHAVIOUR	1102	=head2 FORK BEHAVIOUR
		1103
		1104	This module should do "the right thing" when the process using it forks:
537		1105
538	Before the fork, IO::AIO enters a quiescent state where no requests	1106	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	1107	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	1108	the fork the parent simply leaves the quiescent state and continues
541	request/result processing, while the child clears the request/result	1109	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	1110	(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	1111	parent). Threads will be started on demand until the limit set in the
544	parent process has been reached again.	1112	parent process has been reached again.
545		1113
		1114	In short: the parent will, after a short pause, continue as if fork had
		1115	not been called, while the child will act as if IO::AIO has not been used
		1116	yet.
		1117
		1118	=head2 MEMORY USAGE
		1119
		1120	Per-request usage:
		1121
		1122	Each aio request uses - depending on your architecture - around 100-200
		1123	bytes of memory. In addition, stat requests need a stat buffer (possibly
		1124	a few hundred bytes), readdir requires a result buffer and so on. Perl
		1125	scalars and other data passed into aio requests will also be locked and
		1126	will consume memory till the request has entered the done state.
		1127
		1128	This is now awfully much, so queuing lots of requests is not usually a
		1129	problem.
		1130
		1131	Per-thread usage:
		1132
		1133	In the execution phase, some aio requests require more memory for
		1134	temporary buffers, and each thread requires a stack and other data
		1135	structures (usually around 16k-128k, depending on the OS).
		1136
		1137	=head1 KNOWN BUGS
		1138
		1139	Known bugs will be fixed in the next release.
		1140
546	=head1 SEE ALSO	1141	=head1 SEE ALSO
547		1142
548	L<Coro>, L<Linux::AIO>.	1143	L<Coro::AIO>.
549		1144
550	=head1 AUTHOR	1145	=head1 AUTHOR
551		1146
552	Marc Lehmann <schmorp@schmorp.de>	1147	Marc Lehmann <schmorp@schmorp.de>
553	http://home.schmorp.de/	1148	http://home.schmorp.de/

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Comparing IO-AIO/AIO.pm (file contents): Revision 1.42 by root, Mon Dec 26 18:15:23 2005 UTC vs. Revision 1.86 by root, Sat Oct 28 23:32:29 2006 UTC

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Comparing IO-AIO/AIO.pm (file contents):
Revision 1.42 by root, Mon Dec 26 18:15:23 2005 UTC vs.
Revision 1.86 by root, Sat Oct 28 23:32:29 2006 UTC