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

Comparing IO-AIO/AIO.pm (file contents):
Revision 1.55 by root, Sun Oct 22 00:49:29 2006 UTC vs.
Revision 1.85 by root, Sat Oct 28 01:40:30 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	use IO::AIO 2; # version has aio objects	20	# version 2+ has request and group objects
		21	use IO::AIO 2;
21		22
		23	aioreq_pri 4; # give next request a very high priority
22	my $req = aio_unlink "/tmp/file", sub { };	24	my $req = aio_unlink "/tmp/file", sub { };
23	$req->cancel; # cancel request if still in queue	25	$req->cancel; # cancel request if still in queue
24		26
25	# AnyEvent	27	my $grp = aio_group sub { print "all stats done\n" };
		28	add $grp aio_stat "..." for ...;
		29
		30	# AnyEvent integration
26	open my $fh, "<&=" . IO::AIO::poll_fileno or die "$!";	31	open my $fh, "<&=" . IO::AIO::poll_fileno or die "$!";
27	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 });
28		33
29	# Event	34	# Event integration
30	Event->io (fd => IO::AIO::poll_fileno,	35	Event->io (fd => IO::AIO::poll_fileno,
31	poll => 'r',	36	poll => 'r',
32	cb => \&IO::AIO::poll_cb);	37	cb => \&IO::AIO::poll_cb);
33		38
34	# Glib/Gtk2	39	# Glib/Gtk2 integration
35	add_watch Glib::IO IO::AIO::poll_fileno,	40	add_watch Glib::IO IO::AIO::poll_fileno,
36	in => sub { IO::AIO::poll_cb; 1 };	41	in => sub { IO::AIO::poll_cb; 1 };
37		42
38	# Tk	43	# Tk integration
39	Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",	44	Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
40	readable => \&IO::AIO::poll_cb);	45	readable => \&IO::AIO::poll_cb);
41		46
42	# Danga::Socket	47	# Danga::Socket integration
43	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>	48	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
44	\&IO::AIO::poll_cb);	49	\&IO::AIO::poll_cb);
45		50
46
47	=head1 DESCRIPTION	51	=head1 DESCRIPTION
48		52
49	This module implements asynchronous I/O using whatever means your	53	This module implements asynchronous I/O using whatever means your
50	operating system supports.	54	operating system supports.
51		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
52	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
53	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
54	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
55	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
56	aio functions available on many operating systems. However, they are often	76	functions available on many operating systems. However, they are often
57	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
58	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
59	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.
60		81
61	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-)
62	currently not reentrant, so use appropriate locking yourself, always call	83	threads, it is currently not reentrant in any way, so use appropriate
63	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
64	C<aio_> functions) recursively.	85	never call C<poll_cb> (or other C<aio_> functions) recursively.
		86
		87	=head1 REQUEST ANATOMY AND LIFETIME
		88
		89	Every C<aio_*> function creates a request. which is a C data structure not
		90	directly visible to Perl.
		91
		92	If called in non-void context, every request function returns a Perl
		93	object representing the request. In void context, nothing is returned,
		94	which saves a bit of memory.
		95
		96	The perl object is a fairly standard ref-to-hash object. The hash contents
		97	are not used by IO::AIO so you are free to store anything you like in it.
		98
		99	During their existance, aio requests travel through the following states,
		100	in order:
		101
		102	=over 4
		103
		104	=item ready
		105
		106	Immediately after a request is created it is put into the ready state,
		107	waiting for a thread to execute it.
		108
		109	=item execute
		110
		111	A thread has accepted the request for processing and is currently
		112	executing it (e.g. blocking in read).
		113
		114	=item pending
		115
		116	The request has been executed and is waiting for result processing.
		117
		118	While request submission and execution is fully asynchronous, result
		119	processing is not and relies on the perl interpreter calling C<poll_cb>
		120	(or another function with the same effect).
		121
		122	=item result
		123
		124	The request results are processed synchronously by C<poll_cb>.
		125
		126	The C<poll_cb> function will process all outstanding aio requests by
		127	calling their callbacks, freeing memory associated with them and managing
		128	any groups they are contained in.
		129
		130	=item done
		131
		132	Request has reached the end of its lifetime and holds no resources anymore
		133	(except possibly for the Perl object, but its connection to the actual
		134	aio request is severed and calling its methods will either do nothing or
		135	result in a runtime error).
65		136
66	=cut	137	=cut
67		138
68	package IO::AIO;	139	package IO::AIO;
69		140
…		…
73	use base 'Exporter';	144	use base 'Exporter';
74		145
75	BEGIN {	146	BEGIN {
76	our $VERSION = '2.0';	147	our $VERSION = '2.0';
77		148
78	our @EXPORT = qw(aio_sendfile aio_read aio_write aio_open aio_close aio_stat	149	our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close aio_stat
79	aio_lstat aio_unlink aio_rmdir aio_readdir aio_scandir aio_symlink	150	aio_lstat aio_unlink aio_rmdir aio_readdir aio_scandir aio_symlink
80	aio_fsync aio_fdatasync aio_readahead aio_rename aio_link aio_move	151	aio_fsync aio_fdatasync aio_readahead aio_rename aio_link aio_move
81	aio_group);	152	aio_copy aio_group aio_nop aio_mknod);
82	our @EXPORT_OK = qw(poll_fileno poll_cb min_parallel max_parallel max_outstanding nreqs);	153	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
		154	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
		155	min_parallel max_parallel nreqs nready npending);
83		156
84	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';	157	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';
85		158
86	require XSLoader;	159	require XSLoader;
87	XSLoader::load ("IO::AIO", $VERSION);	160	XSLoader::load ("IO::AIO", $VERSION);
…		…
118	environment, d) use Glib::filename_from_unicode on unicode filenames or e)	191	environment, d) use Glib::filename_from_unicode on unicode filenames or e)
119	use something else.	192	use something else.
120		193
121	=over 4	194	=over 4
122		195
		196	=item $prev_pri = aioreq_pri [$pri]
		197
		198	Returns the priority value that would be used for the next request and, if
		199	C<$pri> is given, sets the priority for the next aio request.
		200
		201	The default priority is C<0>, the minimum and maximum priorities are C<-4>
		202	and C<4>, respectively. Requests with higher priority will be serviced
		203	first.
		204
		205	The priority will be reset to C<0> after each call to one of the C<aio_*>
		206	functions.
		207
		208	Example: open a file with low priority, then read something from it with
		209	higher priority so the read request is serviced before other low priority
		210	open requests (potentially spamming the cache):
		211
		212	aioreq_pri -3;
		213	aio_open ..., sub {
		214	return unless $_[0];
		215
		216	aioreq_pri -2;
		217	aio_read $_[0], ..., sub {
		218	...
		219	};
		220	};
		221
		222	=item aioreq_nice $pri_adjust
		223
		224	Similar to C<aioreq_pri>, but subtracts the given value from the current
		225	priority, so effects are cumulative.
		226
123	=item aio_open $pathname, $flags, $mode, $callback->($fh)	227	=item aio_open $pathname, $flags, $mode, $callback->($fh)
124		228
125	Asynchronously open or create a file and call the callback with a newly	229	Asynchronously open or create a file and call the callback with a newly
126	created filehandle for the file.	230	created filehandle for the file.
127		231
…		…
176		280
177	aio_read $fh, 7, 15, $buffer, 0, sub {	281	aio_read $fh, 7, 15, $buffer, 0, sub {
178	$_[0] > 0 or die "read error: $!";	282	$_[0] > 0 or die "read error: $!";
179	print "read $_[0] bytes: <$buffer>\n";	283	print "read $_[0] bytes: <$buffer>\n";
180	};	284	};
181
182	=item aio_move $srcpath, $dstpath, $callback->($status)
183
184	Try to move the I<file> (directories not supported as either source or
185	destination) from C<$srcpath> to C<$dstpath> and call the callback with
186	the C<0> (error) or C<-1> ok.
187
188	This is a composite request that tries to rename(2) the file first. If
189	rename files with C<EXDEV>, it creates the destination file with mode 0200
190	and copies the contents of the source file into it using C<aio_sendfile>,
191	followed by restoring atime, mtime, access mode and uid/gid, in that
192	order, and unlinking the C<$srcpath>.
193
194	If an error occurs, the partial destination file will be unlinked, if
195	possible, except when setting atime, mtime, access mode and uid/gid, where
196	errors are being ignored.
197
198	=cut
199
200	sub aio_move($$$) {
201	my ($src, $dst, $cb) = @_;
202
203	my $grp = aio_group;
204
205	add $grp aio_rename $src, $dst, sub {
206	if ($_[0] && $! == EXDEV) {
207	add $grp aio_open $src, O_RDONLY, 0, sub {
208	if (my $src_fh = $_[0]) {
209	my @stat = stat $src_fh;
210
211	add $grp aio_open $dst, O_WRONLY, 0200, sub {
212	if (my $dst_fh = $_[0]) {
213	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
214	close $src_fh;
215
216	if ($_[0] == $stat[7]) {
217	utime $stat[8], $stat[9], $dst;
218	chmod $stat[2] & 07777, $dst_fh;
219	chown $stat[4], $stat[5], $dst_fh;
220	close $dst_fh;
221
222	add $grp aio_unlink $src, sub {
223	$cb->($_[0]);
224	};
225	} else {
226	my $errno = $!;
227	add $grp aio_unlink $dst, sub {
228	$! = $errno;
229	$cb->(-1);
230	};
231	}
232	};
233	} else {
234	$cb->(-1);
235	}
236	},
237
238	} else {
239	$cb->(-1);
240	}
241	};
242	} else {
243	$cb->($_[0]);
244	}
245	};
246
247	$grp
248	}
249		285
250	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)	286	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
251		287
252	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts	288	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
253	reading at byte offset C<$in_offset>, and starts writing at the current	289	reading at byte offset C<$in_offset>, and starts writing at the current
…		…
309	=item aio_unlink $pathname, $callback->($status)	345	=item aio_unlink $pathname, $callback->($status)
310		346
311	Asynchronously unlink (delete) a file and call the callback with the	347	Asynchronously unlink (delete) a file and call the callback with the
312	result code.	348	result code.
313		349
		350	=item aio_mknod $path, $mode, $dev, $callback->($status)
		351
		352	Asynchronously create a device node (or fifo). See mknod(2).
		353
		354	The only portable (POSIX) way of calling this function is:
		355
		356	aio_mknod $path, IO::AIO::S_IFIFO \| $mode, 0, sub { ...
		357
314	=item aio_link $srcpath, $dstpath, $callback->($status)	358	=item aio_link $srcpath, $dstpath, $callback->($status)
315		359
316	Asynchronously create a new link to the existing object at C<$srcpath> at	360	Asynchronously create a new link to the existing object at C<$srcpath> at
317	the path C<$dstpath> and call the callback with the result code.	361	the path C<$dstpath> and call the callback with the result code.
318		362
…		…
338	sorted, and will B<NOT> include the C<.> and C<..> entries.	382	sorted, and will B<NOT> include the C<.> and C<..> entries.
339		383
340	The callback a single argument which is either C<undef> or an array-ref	384	The callback a single argument which is either C<undef> or an array-ref
341	with the filenames.	385	with the filenames.
342		386
		387	=item aio_copy $srcpath, $dstpath, $callback->($status)
		388
		389	Try to copy the I<file> (directories not supported as either source or
		390	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		391	the C<0> (error) or C<-1> ok.
		392
		393	This is a composite request that it creates the destination file with
		394	mode 0200 and copies the contents of the source file into it using
		395	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
		396	uid/gid, in that order.
		397
		398	If an error occurs, the partial destination file will be unlinked, if
		399	possible, except when setting atime, mtime, access mode and uid/gid, where
		400	errors are being ignored.
		401
		402	=cut
		403
		404	sub aio_copy($$;$) {
		405	my ($src, $dst, $cb) = @_;
		406
		407	my $pri = aioreq_pri;
		408	my $grp = aio_group $cb;
		409
		410	aioreq_pri $pri;
		411	add $grp aio_open $src, O_RDONLY, 0, sub {
		412	if (my $src_fh = $_[0]) {
		413	my @stat = stat $src_fh;
		414
		415	aioreq_pri $pri;
		416	add $grp aio_open $dst, O_CREAT \| O_WRONLY \| O_TRUNC, 0200, sub {
		417	if (my $dst_fh = $_[0]) {
		418	aioreq_pri $pri;
		419	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
		420	if ($_[0] == $stat[7]) {
		421	$grp->result (0);
		422	close $src_fh;
		423
		424	# those should not normally block. should. should.
		425	utime $stat[8], $stat[9], $dst;
		426	chmod $stat[2] & 07777, $dst_fh;
		427	chown $stat[4], $stat[5], $dst_fh;
		428	close $dst_fh;
		429	} else {
		430	$grp->result (-1);
		431	close $src_fh;
		432	close $dst_fh;
		433
		434	aioreq $pri;
		435	add $grp aio_unlink $dst;
		436	}
		437	};
		438	} else {
		439	$grp->result (-1);
		440	}
		441	},
		442
		443	} else {
		444	$grp->result (-1);
		445	}
		446	};
		447
		448	$grp
		449	}
		450
		451	=item aio_move $srcpath, $dstpath, $callback->($status)
		452
		453	Try to move the I<file> (directories not supported as either source or
		454	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		455	the C<0> (error) or C<-1> ok.
		456
		457	This is a composite request that tries to rename(2) the file first. If
		458	rename files with C<EXDEV>, it copies the file with C<aio_copy> and, if
		459	that is successful, unlinking the C<$srcpath>.
		460
		461	=cut
		462
		463	sub aio_move($$;$) {
		464	my ($src, $dst, $cb) = @_;
		465
		466	my $pri = aioreq_pri;
		467	my $grp = aio_group $cb;
		468
		469	aioreq_pri $pri;
		470	add $grp aio_rename $src, $dst, sub {
		471	if ($_[0] && $! == EXDEV) {
		472	aioreq_pri $pri;
		473	add $grp aio_copy $src, $dst, sub {
		474	$grp->result ($_[0]);
		475
		476	if (!$_[0]) {
		477	aioreq_pri $pri;
		478	add $grp aio_unlink $src;
		479	}
		480	};
		481	} else {
		482	$grp->result ($_[0]);
		483	}
		484	};
		485
		486	$grp
		487	}
		488
343	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	489	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
344		490
345	Scans a directory (similar to C<aio_readdir>) but additionally tries to	491	Scans a directory (similar to C<aio_readdir>) but additionally tries to
346	separate the entries of directory C<$path> into two sets of names, ones	492	efficiently separate the entries of directory C<$path> into two sets of
347	you can recurse into (directories or links to them), and ones you cannot	493	names, directories you can recurse into (directories), and ones you cannot
348	recurse into (everything else).	494	recurse into (everything else, including symlinks to directories).
349		495
350	C<aio_scandir> is a composite request that consists of many sub	496	C<aio_scandir> is a composite request that creates of many sub requests_
351	requests. C<$maxreq> specifies the maximum number of outstanding aio	497	C<$maxreq> specifies the maximum number of outstanding aio requests that
352	requests that this function generates. If it is C<< <= 0 >>, then a	498	this function generates. If it is C<< <= 0 >>, then a suitable default
353	suitable default will be chosen (currently 8).	499	will be chosen (currently 4).
354		500
355	On error, the callback is called without arguments, otherwise it receives	501	On error, the callback is called without arguments, otherwise it receives
356	two array-refs with path-relative entry names.	502	two array-refs with path-relative entry names.
357		503
358	Example:	504	Example:
…		…
395	=cut	541	=cut
396		542
397	sub aio_scandir($$$) {	543	sub aio_scandir($$$) {
398	my ($path, $maxreq, $cb) = @_;	544	my ($path, $maxreq, $cb) = @_;
399		545
		546	my $pri = aioreq_pri;
		547
400	my $grp = aio_group;	548	my $grp = aio_group $cb;
401		549
402	$maxreq = 8 if $maxreq <= 0;	550	$maxreq = 4 if $maxreq <= 0;
403		551
404	# stat once	552	# stat once
		553	aioreq_pri $pri;
405	add $grp aio_stat $path, sub {	554	add $grp aio_stat $path, sub {
406	return $cb->() if $_[0];	555	return $grp->result () if $_[0];
407	my $now = time;	556	my $now = time;
408	my $hash1 = join ":", (stat _)[0,1,3,7,9];	557	my $hash1 = join ":", (stat _)[0,1,3,7,9];
409		558
410	# read the directory entries	559	# read the directory entries
		560	aioreq_pri $pri;
411	add $grp aio_readdir $path, sub {	561	add $grp aio_readdir $path, sub {
412	my $entries = shift	562	my $entries = shift
413	or return $cb->();	563	or return $grp->result ();
414		564
415	# stat the dir another time	565	# stat the dir another time
		566	aioreq_pri $pri;
416	add $grp aio_stat $path, sub {	567	add $grp aio_stat $path, sub {
417	my $hash2 = join ":", (stat _)[0,1,3,7,9];	568	my $hash2 = join ":", (stat _)[0,1,3,7,9];
418		569
419	my $ndirs;	570	my $ndirs;
420		571
…		…
423	$ndirs = -1;	574	$ndirs = -1;
424	} else {	575	} else {
425	# if nlink == 2, we are finished	576	# if nlink == 2, we are finished
426	# on non-posix-fs's, we rely on nlink < 2	577	# on non-posix-fs's, we rely on nlink < 2
427	$ndirs = (stat _)[3] - 2	578	$ndirs = (stat _)[3] - 2
428	or return $cb->([], $entries);	579	or return $grp->result ([], $entries);
429	}	580	}
430		581
431	# sort into likely dirs and likely nondirs	582	# sort into likely dirs and likely nondirs
432	# dirs == files without ".", short entries first	583	# dirs == files without ".", short entries first
433	$entries = [map $_->[0],	584	$entries = [map $_->[0],
…		…
435	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],	586	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
436	@$entries];	587	@$entries];
437		588
438	my (@dirs, @nondirs);	589	my (@dirs, @nondirs);
439		590
440	my ($statcb, $schedcb);	591	my $statgrp = add $grp aio_group sub {
441	my $nreq = 0;	592	$grp->result (\@dirs, \@nondirs);
		593	};
442		594
443	$schedcb = sub {	595	limit $statgrp $maxreq;
444	if (@$entries) {	596	feed $statgrp sub {
445	if ($nreq < $maxreq) {	597	return unless @$entries;
446	my $ent = pop @$entries;	598	my $entry = pop @$entries;
		599
		600	aioreq_pri $pri;
		601	add $statgrp aio_stat "$path/$entry/.", sub {
		602	if ($_[0] < 0) {
		603	push @nondirs, $entry;
		604	} else {
		605	# need to check for real directory
		606	aioreq_pri $pri;
		607	add $statgrp aio_lstat "$path/$entry", sub {
		608	if (-d _) {
		609	push @dirs, $entry;
		610
		611	unless (--$ndirs) {
		612	push @nondirs, @$entries;
		613	feed $statgrp;
		614	}
		615	} else {
		616	push @nondirs, $entry;
		617	}
447	$nreq++;	618	}
448	add $grp aio_stat "$path/$ent/.", sub { $statcb->($_[0], $ent) };
449	}	619	}
450	} elsif (!$nreq) {
451	# finished
452	undef $statcb;
453	undef $schedcb;
454	$cb->(\@dirs, \@nondirs) if $cb;
455	undef $cb;
456	}	620	};
457	};	621	};
458	$statcb = sub {
459	my ($status, $entry) = @_;
460
461	if ($status < 0) {
462	$nreq--;
463	push @nondirs, $entry;
464	&$schedcb;
465	} else {
466	# need to check for real directory
467	add $grp aio_lstat "$path/$entry", sub {
468	$nreq--;
469
470	if (-d _) {
471	push @dirs, $entry;
472
473	if (!--$ndirs) {
474	push @nondirs, @$entries;
475	$entries = [];
476	}
477	} else {
478	push @nondirs, $entry;
479	}
480
481	&$schedcb;
482	}
483	}
484	};
485
486	&$schedcb while @$entries && $nreq < $maxreq;
487	};	622	};
488	};	623	};
489	};	624	};
490		625
491	$grp	626	$grp
…		…
502	callback with the fdatasync result code.	637	callback with the fdatasync result code.
503		638
504	If this call isn't available because your OS lacks it or it couldn't be	639	If this call isn't available because your OS lacks it or it couldn't be
505	detected, it will be emulated by calling C<fsync> instead.	640	detected, it will be emulated by calling C<fsync> instead.
506		641
507	=item aio_group $callback->()	642	=item aio_group $callback->(...)
508
509	[EXPERIMENTAL]
510		643
511	This is a very special aio request: Instead of doing something, it is a	644	This is a very special aio request: Instead of doing something, it is a
512	container for other aio requests, which is useful if you want to bundle	645	container for other aio requests, which is useful if you want to bundle
513	many requests into a single, composite, request.	646	many requests into a single, composite, request with a definite callback
		647	and the ability to cancel the whole request with its subrequests.
514		648
515	Returns an object of class L<IO::AIO::GRP>. See its documentation below	649	Returns an object of class L<IO::AIO::GRP>. See its documentation below
516	for more info.	650	for more info.
517		651
518	Example:	652	Example:
…		…
524	add $grp	658	add $grp
525	(aio_stat ...),	659	(aio_stat ...),
526	(aio_stat ...),	660	(aio_stat ...),
527	...;	661	...;
528		662
		663	=item aio_nop $callback->()
		664
		665	This is a special request - it does nothing in itself and is only used for
		666	side effects, such as when you want to add a dummy request to a group so
		667	that finishing the requests in the group depends on executing the given
		668	code.
		669
		670	While this request does nothing, it still goes through the execution
		671	phase and still requires a worker thread. Thus, the callback will not
		672	be executed immediately but only after other requests in the queue have
		673	entered their execution phase. This can be used to measure request
		674	latency.
		675
529	=item aio_sleep $fractional_seconds, $callback->() NOT EXPORTED	676	=item IO::AIO::aio_busy $fractional_seconds, $callback->() NOT EXPORTED
530		677
531	Mainly used for debugging and benchmarking, this aio request puts one of	678	Mainly used for debugging and benchmarking, this aio request puts one of
532	the request workers to sleep for the given time.	679	the request workers to sleep for the given time.
533		680
		681	While it is theoretically handy to have simple I/O scheduling requests
		682	like sleep and file handle readable/writable, the overhead this creates is
		683	immense (it blocks a thread for a long time) so do not use this function
		684	except to put your application under artificial I/O pressure.
		685
534	=back	686	=back
535		687
536	=head2 IO::AIO::REQ CLASS	688	=head2 IO::AIO::REQ CLASS
537		689
538	All non-aggregate C<aio_*> functions return an object of this class when	690	All non-aggregate C<aio_*> functions return an object of this class when
539	called in non-void context.	691	called in non-void context.
540		692
541	A request always moves through the following five states in its lifetime,
542	in order: B<ready> (request has been created, but has not been executed
543	yet), B<execute> (request is currently being executed), B<pending>
544	(request has been executed but callback has not been called yet),
545	B<result> (results are being processed synchronously, includes calling the
546	callback) and B<done> (request has reached the end of its lifetime and
547	holds no resources anymore).
548
549	=over 4	693	=over 4
550		694
551	=item $req->cancel	695	=item cancel $req
552		696
553	Cancels the request, if possible. Has the effect of skipping execution	697	Cancels the request, if possible. Has the effect of skipping execution
554	when entering the B<execute> state and skipping calling the callback when	698	when entering the B<execute> state and skipping calling the callback when
555	entering the the B<result> state, but will leave the request otherwise	699	entering the the B<result> state, but will leave the request otherwise
556	untouched. That means that requests that currently execute will not be	700	untouched. That means that requests that currently execute will not be
557	stopped and resources held by the request will not be freed prematurely.	701	stopped and resources held by the request will not be freed prematurely.
558		702
		703	=item cb $req $callback->(...)
		704
		705	Replace (or simply set) the callback registered to the request.
		706
559	=back	707	=back
560		708
561	=head2 IO::AIO::GRP CLASS	709	=head2 IO::AIO::GRP CLASS
562		710
563	This class is a subclass of L<IO::AIO::REQ>, so all its methods apply to	711	This class is a subclass of L<IO::AIO::REQ>, so all its methods apply to
…		…
577	You add requests by calling the C<add> method with one or more	725	You add requests by calling the C<add> method with one or more
578	C<IO::AIO::REQ> objects:	726	C<IO::AIO::REQ> objects:
579		727
580	$grp->add (aio_unlink "...");	728	$grp->add (aio_unlink "...");
581		729
582	add $grp aio_stat "...", sub { ... };	730	add $grp aio_stat "...", sub {
		731	$_[0] or return $grp->result ("error");
		732
		733	# add another request dynamically, if first succeeded
		734	add $grp aio_open "...", sub {
		735	$grp->result ("ok");
		736	};
		737	};
583		738
584	This makes it very easy to create composite requests (see the source of	739	This makes it very easy to create composite requests (see the source of
585	C<aio_move> for an application) that work and feel like simple requests.	740	C<aio_move> for an application) that work and feel like simple requests.
586		741
		742	=over 4
		743
587	The IO::AIO::GRP objects will be cleaned up during calls to	744	=item * The IO::AIO::GRP objects will be cleaned up during calls to
588	C<IO::AIO::poll_cb>, just like any other request.	745	C<IO::AIO::poll_cb>, just like any other request.
589		746
590	They can be canceled like any other request. Canceling will cancel not	747	=item * They can be canceled like any other request. Canceling will cancel not
591	just the request itself, but also all requests it contains.	748	only the request itself, but also all requests it contains.
592		749
593	They can also can also be added to other IO::AIO::GRP objects.	750	=item * They can also can also be added to other IO::AIO::GRP objects.
		751
		752	=item * You must not add requests to a group from within the group callback (or
		753	any later time).
		754
		755	=back
594		756
595	Their lifetime, simplified, looks like this: when they are empty, they	757	Their lifetime, simplified, looks like this: when they are empty, they
596	will finish very quickly. If they contain only requests that are in the	758	will finish very quickly. If they contain only requests that are in the
597	C<done> state, they will also finish. Otherwise they will continue to	759	C<done> state, they will also finish. Otherwise they will continue to
598	exist.	760	exist.
599		761
		762	That means after creating a group you have some time to add requests. And
		763	in the callbacks of those requests, you can add further requests to the
		764	group. And only when all those requests have finished will the the group
		765	itself finish.
		766
600	=over 4	767	=over 4
601		768
		769	=item add $grp ...
		770
602	=item $grp->add (...)	771	=item $grp->add (...)
603		772
604	=item add $grp ...	773	Add one or more requests to the group. Any type of L<IO::AIO::REQ> can
		774	be added, including other groups, as long as you do not create circular
		775	dependencies.
605		776
606	Add one or more	777	Returns all its arguments.
607	Cancels the request, if possible. Has the effect of skipping execution	778
608	when entering the B<execute> state and skipping calling the callback when	779	=item $grp->cancel_subs
609	entering the the B<result> state, but will leave the request otherwise	780
610	untouched. That means that requests that currently execute will not be	781	Cancel all subrequests and clears any feeder, but not the group request
611	stopped and resources held by the request will not be freed prematurely.	782	itself. Useful when you queued a lot of events but got a result early.
		783
		784	=item $grp->result (...)
		785
		786	Set the result value(s) that will be passed to the group callback when all
		787	subrequests have finished and set thre groups errno to the current value
		788	of errno (just like calling C<errno> without an error number). By default,
		789	no argument will be passed and errno is zero.
		790
		791	=item $grp->errno ([$errno])
		792
		793	Sets the group errno value to C<$errno>, or the current value of errno
		794	when the argument is missing.
		795
		796	Every aio request has an associated errno value that is restored when
		797	the callback is invoked. This method lets you change this value from its
		798	default (0).
		799
		800	Calling C<result> will also set errno, so make sure you either set C<$!>
		801	before the call to C<result>, or call c<errno> after it.
		802
		803	=item feed $grp $callback->($grp)
		804
		805	Sets a feeder/generator on this group: every group can have an attached
		806	generator that generates requests if idle. The idea behind this is that,
		807	although you could just queue as many requests as you want in a group,
		808	this might starve other requests for a potentially long time. For
		809	example, C<aio_scandir> might generate hundreds of thousands C<aio_stat>
		810	requests, delaying any later requests for a long time.
		811
		812	To avoid this, and allow incremental generation of requests, you can
		813	instead a group and set a feeder on it that generates those requests. The
		814	feed callback will be called whenever there are few enough (see C<limit>,
		815	below) requests active in the group itself and is expected to queue more
		816	requests.
		817
		818	The feed callback can queue as many requests as it likes (i.e. C<add> does
		819	not impose any limits).
		820
		821	If the feed does not queue more requests when called, it will be
		822	automatically removed from the group.
		823
		824	If the feed limit is C<0>, it will be set to C<2> automatically.
		825
		826	Example:
		827
		828	# stat all files in @files, but only ever use four aio requests concurrently:
		829
		830	my $grp = aio_group sub { print "finished\n" };
		831	limit $grp 4;
		832	feed $grp sub {
		833	my $file = pop @files
		834	or return;
		835
		836	add $grp aio_stat $file, sub { ... };
		837	};
		838
		839	=item limit $grp $num
		840
		841	Sets the feeder limit for the group: The feeder will be called whenever
		842	the group contains less than this many requests.
		843
		844	Setting the limit to C<0> will pause the feeding process.
612		845
613	=back	846	=back
614		847
615	=head2 SUPPORT FUNCTIONS	848	=head2 SUPPORT FUNCTIONS
616		849
…		…
629		862
630	Process all outstanding events on the result pipe. You have to call this	863	Process all outstanding events on the result pipe. You have to call this
631	regularly. Returns the number of events processed. Returns immediately	864	regularly. Returns the number of events processed. Returns immediately
632	when no events are outstanding.	865	when no events are outstanding.
633		866
		867	If not all requests were processed for whatever reason, the filehandle
		868	will still be ready when C<poll_cb> returns.
		869
634	Example: Install an Event watcher that automatically calls	870	Example: Install an Event watcher that automatically calls
635	IO::AIO::poll_cb with high priority:	871	IO::AIO::poll_cb with high priority:
636		872
637	Event->io (fd => IO::AIO::poll_fileno,	873	Event->io (fd => IO::AIO::poll_fileno,
638	poll => 'r', async => 1,	874	poll => 'r', async => 1,
639	cb => \&IO::AIO::poll_cb);	875	cb => \&IO::AIO::poll_cb);
640		876
		877	=item IO::AIO::poll_some $max_requests
		878
		879	Similar to C<poll_cb>, but only processes up to C<$max_requests> requests
		880	at a time.
		881
		882	Useful if you want to ensure some level of interactiveness when perl is
		883	not fast enough to process all requests in time.
		884
		885	Example: Install an Event watcher that automatically calls
		886	IO::AIO::poll_some with low priority, to ensure that other parts of the
		887	program get the CPU sometimes even under high AIO load.
		888
		889	Event->io (fd => IO::AIO::poll_fileno,
		890	poll => 'r', nice => 1,
		891	cb => sub { IO::AIO::poll_some 256 });
		892
641	=item IO::AIO::poll_wait	893	=item IO::AIO::poll_wait
642		894
643	Wait till the result filehandle becomes ready for reading (simply does a	895	Wait till the result filehandle becomes ready for reading (simply does a
644	C<select> on the filehandle. This is useful if you want to synchronously wait	896	C<select> on the filehandle. This is useful if you want to synchronously wait
645	for some requests to finish).	897	for some requests to finish).
646		898
647	See C<nreqs> for an example.	899	See C<nreqs> for an example.
648		900
649	=item IO::AIO::nreqs	901	=item IO::AIO::nreqs
650		902
651	Returns the number of requests currently outstanding (i.e. for which their	903	Returns the number of requests currently in the ready, execute or pending
652	callback has not been invoked yet).	904	states (i.e. for which their callback has not been invoked yet).
653		905
654	Example: wait till there are no outstanding requests anymore:	906	Example: wait till there are no outstanding requests anymore:
655		907
656	IO::AIO::poll_wait, IO::AIO::poll_cb	908	IO::AIO::poll_wait, IO::AIO::poll_cb
657	while IO::AIO::nreqs;	909	while IO::AIO::nreqs;
658		910
		911	=item IO::AIO::nready
		912
		913	Returns the number of requests currently in the ready state (not yet
		914	executed).
		915
		916	=item IO::AIO::npending
		917
		918	Returns the number of requests currently in the pending state (executed,
		919	but not yet processed by poll_cb).
		920
659	=item IO::AIO::flush	921	=item IO::AIO::flush
660		922
661	Wait till all outstanding AIO requests have been handled.	923	Wait till all outstanding AIO requests have been handled.
662		924
663	Strictly equivalent to:	925	Strictly equivalent to:
…		…
674	IO::AIO::poll_wait, IO::AIO::poll_cb	936	IO::AIO::poll_wait, IO::AIO::poll_cb
675	if IO::AIO::nreqs;	937	if IO::AIO::nreqs;
676		938
677	=item IO::AIO::min_parallel $nthreads	939	=item IO::AIO::min_parallel $nthreads
678		940
679	Set the minimum number of AIO threads to C<$nthreads>. The current default	941	Set the minimum number of AIO threads to C<$nthreads>. The current
680	is C<4>, which means four asynchronous operations can be done at one time	942	default is C<8>, which means eight asynchronous operations can execute
681	(the number of outstanding operations, however, is unlimited).	943	concurrently at any one time (the number of outstanding requests,
		944	however, is unlimited).
682		945
683	IO::AIO starts threads only on demand, when an AIO request is queued and	946	IO::AIO starts threads only on demand, when an AIO request is queued and
684	no free thread exists.	947	no free thread exists.
685		948
686	It is recommended to keep the number of threads low, as some Linux	949	It is recommended to keep the number of threads relatively low, as some
687	kernel versions will scale negatively with the number of threads (higher	950	Linux kernel versions will scale negatively with the number of threads
688	parallelity => MUCH higher latency). With current Linux 2.6 versions, 4-32	951	(higher parallelity => MUCH higher latency). With current Linux 2.6
689	threads should be fine.	952	versions, 4-32 threads should be fine.
690		953
691	Under most circumstances you don't need to call this function, as the	954	Under most circumstances you don't need to call this function, as the
692	module selects a default that is suitable for low to moderate load.	955	module selects a default that is suitable for low to moderate load.
693		956
694	=item IO::AIO::max_parallel $nthreads	957	=item IO::AIO::max_parallel $nthreads
…		…
703	This module automatically runs C<max_parallel 0> at program end, to ensure	966	This module automatically runs C<max_parallel 0> at program end, to ensure
704	that all threads are killed and that there are no outstanding requests.	967	that all threads are killed and that there are no outstanding requests.
705		968
706	Under normal circumstances you don't need to call this function.	969	Under normal circumstances you don't need to call this function.
707		970
708	=item $oldnreqs = IO::AIO::max_outstanding $nreqs	971	=item $oldmaxreqs = IO::AIO::max_outstanding $maxreqs
		972
		973	This is a very bad function to use in interactive programs because it
		974	blocks, and a bad way to reduce concurrency because it is inexact: Better
		975	use an C<aio_group> together with a feed callback.
709		976
710	Sets the maximum number of outstanding requests to C<$nreqs>. If you	977	Sets the maximum number of outstanding requests to C<$nreqs>. If you
711	try to queue up more than this number of requests, the caller will block until	978	to queue up more than this number of requests, the next call to the
712	some requests have been handled.	979	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
		980	function will block until the limit is no longer exceeded.
713		981
714	The default is very large, so normally there is no practical limit. If you	982	The default value is very large, so there is no practical limit on the
715	queue up many requests in a loop it often improves speed if you set	983	number of outstanding requests.
716	this to a relatively low number, such as C<100>.
717		984
718	Under normal circumstances you don't need to call this function.	985	You can still queue as many requests as you want. Therefore,
		986	C<max_oustsanding> is mainly useful in simple scripts (with low values) or
		987	as a stop gap to shield against fatal memory overflow (with large values).
719		988
720	=back	989	=back
721		990
722	=cut	991	=cut
723		992
…		…
735	or return undef;	1004	or return undef;
736		1005
737	*$sym	1006	*$sym
738	}	1007	}
739		1008
740	min_parallel 4;	1009	min_parallel 8;
741		1010
742	END {	1011	END {
743	max_parallel 0;	1012	min_parallel 1;
744	}	1013	flush;
		1014	};
745		1015
746	1;	1016	1;
747		1017
748	=head2 FORK BEHAVIOUR	1018	=head2 FORK BEHAVIOUR
749		1019
750	This module should do "the right thing" when the process using it forks:	1020	This module should do "the right thing" when the process using it forks:
751		1021
752	Before the fork, IO::AIO enters a quiescent state where no requests	1022	Before the fork, IO::AIO enters a quiescent state where no requests
753	can be added in other threads and no results will be processed. After	1023	can be added in other threads and no results will be processed. After
754	the fork the parent simply leaves the quiescent state and continues	1024	the fork the parent simply leaves the quiescent state and continues
755	request/result processing, while the child clears the request/result	1025	request/result processing, while the child frees the request/result queue
756	queue (so the requests started before the fork will only be handled in	1026	(so that the requests started before the fork will only be handled in the
757	the parent). Threads will be started on demand until the limit ste in the	1027	parent). Threads will be started on demand until the limit set in the
758	parent process has been reached again.	1028	parent process has been reached again.
759		1029
760	In short: the parent will, after a short pause, continue as if fork had	1030	In short: the parent will, after a short pause, continue as if fork had
761	not been called, while the child will act as if IO::AIO has not been used	1031	not been called, while the child will act as if IO::AIO has not been used
762	yet.	1032	yet.
763		1033
		1034	=head2 MEMORY USAGE
		1035
		1036	Per-request usage:
		1037
		1038	Each aio request uses - depending on your architecture - around 100-200
		1039	bytes of memory. In addition, stat requests need a stat buffer (possibly
		1040	a few hundred bytes), readdir requires a result buffer and so on. Perl
		1041	scalars and other data passed into aio requests will also be locked and
		1042	will consume memory till the request has entered the done state.
		1043
		1044	This is now awfully much, so queuing lots of requests is not usually a
		1045	problem.
		1046
		1047	Per-thread usage:
		1048
		1049	In the execution phase, some aio requests require more memory for
		1050	temporary buffers, and each thread requires a stack and other data
		1051	structures (usually around 16k-128k, depending on the OS).
		1052
		1053	=head1 KNOWN BUGS
		1054
		1055	Known bugs will be fixed in the next release.
		1056
764	=head1 SEE ALSO	1057	=head1 SEE ALSO
765		1058
766	L<Coro>, L<Linux::AIO> (obsolete).	1059	L<Coro::AIO>.
767		1060
768	=head1 AUTHOR	1061	=head1 AUTHOR
769		1062
770	Marc Lehmann <schmorp@schmorp.de>	1063	Marc Lehmann <schmorp@schmorp.de>
771	http://home.schmorp.de/	1064	http://home.schmorp.de/

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Comparing IO-AIO/AIO.pm (file contents): Revision 1.55 by root, Sun Oct 22 00:49:29 2006 UTC vs. Revision 1.85 by root, Sat Oct 28 01:40:30 2006 UTC

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Comparing IO-AIO/AIO.pm (file contents):
Revision 1.55 by root, Sun Oct 22 00:49:29 2006 UTC vs.
Revision 1.85 by root, Sat Oct 28 01:40:30 2006 UTC