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

Comparing IO-AIO/AIO.pm (file contents):
Revision 1.52 by root, Sat Oct 21 23:06:04 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
…		…
71	use strict 'vars';	142	use strict 'vars';
72		143
73	use base 'Exporter';	144	use base 'Exporter';
74		145
75	BEGIN {	146	BEGIN {
76	our $VERSION = '1.8';	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	our @EXPORT_OK = qw(poll_fileno poll_cb min_parallel max_parallel max_outstanding nreqs);	152	aio_copy aio_group aio_nop aio_mknod);
		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);
		156
		157	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';
82		158
83	require XSLoader;	159	require XSLoader;
84	XSLoader::load ("IO::AIO", $VERSION);	160	XSLoader::load ("IO::AIO", $VERSION);
85	}	161	}
86		162
…		…
97	syscall has been executed asynchronously.	173	syscall has been executed asynchronously.
98		174
99	All functions expecting a filehandle keep a copy of the filehandle	175	All functions expecting a filehandle keep a copy of the filehandle
100	internally until the request has finished.	176	internally until the request has finished.
101		177
102	All non-composite requests (requests that are not broken down into
103	multiple requests) return objects of type L<IO::AIO::REQ> that allow	178	All requests return objects of type L<IO::AIO::REQ> that allow further
104	further manipulation of running requests.	179	manipulation of those requests while they are in-flight.
105		180
106	The pathnames you pass to these routines I<must> be absolute and	181	The pathnames you pass to these routines I<must> be absolute and
107	encoded in byte form. The reason for the former is that at the time the	182	encoded in byte form. The reason for the former is that at the time the
108	request is being executed, the current working directory could have	183	request is being executed, the current working directory could have
109	changed. Alternatively, you can make sure that you never change the	184	changed. Alternatively, you can make sure that you never change the
…		…
115	your pathnames to the locale (or other) encoding in effect in the user	190	your pathnames to the locale (or other) encoding in effect in the user
116	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)
117	use something else.	192	use something else.
118		193
119	=over 4	194	=over 4
		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.
120		226
121	=item aio_open $pathname, $flags, $mode, $callback->($fh)	227	=item aio_open $pathname, $flags, $mode, $callback->($fh)
122		228
123	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
124	created filehandle for the file.	230	created filehandle for the file.
…		…
174		280
175	aio_read $fh, 7, 15, $buffer, 0, sub {	281	aio_read $fh, 7, 15, $buffer, 0, sub {
176	$_[0] > 0 or die "read error: $!";	282	$_[0] > 0 or die "read error: $!";
177	print "read $_[0] bytes: <$buffer>\n";	283	print "read $_[0] bytes: <$buffer>\n";
178	};	284	};
179
180	=item aio_move $srcpath, $dstpath, $callback->($status)
181
182	Try to move the I<file> (directories not supported as either source or
183	destination) from C<$srcpath> to C<$dstpath> and call the callback with
184	the C<0> (error) or C<-1> ok.
185
186	This is a composite request that tries to rename(2) the file first. If
187	rename files with C<EXDEV>, it creates the destination file with mode 0200
188	and copies the contents of the source file into it using C<aio_sendfile>,
189	followed by restoring atime, mtime, access mode and uid/gid, in that
190	order, and unlinking the C<$srcpath>.
191
192	If an error occurs, the partial destination file will be unlinked, if
193	possible, except when setting atime, mtime, access mode and uid/gid, where
194	errors are being ignored.
195
196	=cut
197
198	sub aio_move($$$) {
199	my ($src, $dst, $cb) = @_;
200
201	aio_rename $src, $dst, sub {
202	if ($_[0] && $! == EXDEV) {
203	aio_open $src, O_RDONLY, 0, sub {
204	if (my $src_fh = $_[0]) {
205	my @stat = stat $src_fh;
206
207	aio_open $dst, O_WRONLY, 0200, sub {
208	if (my $dst_fh = $_[0]) {
209	aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
210	close $src_fh;
211
212	if ($_[0] == $stat[7]) {
213	utime $stat[8], $stat[9], $dst;
214	chmod $stat[2] & 07777, $dst_fh;
215	chown $stat[4], $stat[5], $dst_fh;
216	close $dst_fh;
217
218	aio_unlink $src, sub {
219	$cb->($_[0]);
220	};
221	} else {
222	my $errno = $!;
223	aio_unlink $dst, sub {
224	$! = $errno;
225	$cb->(-1);
226	};
227	}
228	};
229	} else {
230	$cb->(-1);
231	}
232	},
233
234	} else {
235	$cb->(-1);
236	}
237	};
238	} else {
239	$cb->($_[0]);
240	}
241	};
242	}
243		285
244	=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)
245		287
246	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
247	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
…		…
303	=item aio_unlink $pathname, $callback->($status)	345	=item aio_unlink $pathname, $callback->($status)
304		346
305	Asynchronously unlink (delete) a file and call the callback with the	347	Asynchronously unlink (delete) a file and call the callback with the
306	result code.	348	result code.
307		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
308	=item aio_link $srcpath, $dstpath, $callback->($status)	358	=item aio_link $srcpath, $dstpath, $callback->($status)
309		359
310	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
311	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.
312		362
…		…
332	sorted, and will B<NOT> include the C<.> and C<..> entries.	382	sorted, and will B<NOT> include the C<.> and C<..> entries.
333		383
334	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
335	with the filenames.	385	with the filenames.
336		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
337	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	489	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
338		490
339	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
340	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
341	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
342	recurse into (everything else).	494	recurse into (everything else, including symlinks to directories).
343		495
344	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_
345	requests. C<$maxreq> specifies the maximum number of outstanding aio	497	C<$maxreq> specifies the maximum number of outstanding aio requests that
346	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
347	suitable default will be chosen (currently 8).	499	will be chosen (currently 4).
348		500
349	On error, the callback is called without arguments, otherwise it receives	501	On error, the callback is called without arguments, otherwise it receives
350	two array-refs with path-relative entry names.	502	two array-refs with path-relative entry names.
351		503
352	Example:	504	Example:
…		…
389	=cut	541	=cut
390		542
391	sub aio_scandir($$$) {	543	sub aio_scandir($$$) {
392	my ($path, $maxreq, $cb) = @_;	544	my ($path, $maxreq, $cb) = @_;
393		545
		546	my $pri = aioreq_pri;
		547
		548	my $grp = aio_group $cb;
		549
394	$maxreq = 8 if $maxreq <= 0;	550	$maxreq = 4 if $maxreq <= 0;
395		551
396	# stat once	552	# stat once
		553	aioreq_pri $pri;
397	aio_stat $path, sub {	554	add $grp aio_stat $path, sub {
398	return $cb->() if $_[0];	555	return $grp->result () if $_[0];
399	my $now = time;	556	my $now = time;
400	my $hash1 = join ":", (stat _)[0,1,3,7,9];	557	my $hash1 = join ":", (stat _)[0,1,3,7,9];
401		558
402	# read the directory entries	559	# read the directory entries
		560	aioreq_pri $pri;
403	aio_readdir $path, sub {	561	add $grp aio_readdir $path, sub {
404	my $entries = shift	562	my $entries = shift
405	or return $cb->();	563	or return $grp->result ();
406		564
407	# stat the dir another time	565	# stat the dir another time
		566	aioreq_pri $pri;
408	aio_stat $path, sub {	567	add $grp aio_stat $path, sub {
409	my $hash2 = join ":", (stat _)[0,1,3,7,9];	568	my $hash2 = join ":", (stat _)[0,1,3,7,9];
410		569
411	my $ndirs;	570	my $ndirs;
412		571
413	# take the slow route if anything looks fishy	572	# take the slow route if anything looks fishy
…		…
415	$ndirs = -1;	574	$ndirs = -1;
416	} else {	575	} else {
417	# if nlink == 2, we are finished	576	# if nlink == 2, we are finished
418	# on non-posix-fs's, we rely on nlink < 2	577	# on non-posix-fs's, we rely on nlink < 2
419	$ndirs = (stat _)[3] - 2	578	$ndirs = (stat _)[3] - 2
420	or return $cb->([], $entries);	579	or return $grp->result ([], $entries);
421	}	580	}
422		581
423	# sort into likely dirs and likely nondirs	582	# sort into likely dirs and likely nondirs
424	# dirs == files without ".", short entries first	583	# dirs == files without ".", short entries first
425	$entries = [map $_->[0],	584	$entries = [map $_->[0],
…		…
427	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],	586	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
428	@$entries];	587	@$entries];
429		588
430	my (@dirs, @nondirs);	589	my (@dirs, @nondirs);
431		590
432	my ($statcb, $schedcb);	591	my $statgrp = add $grp aio_group sub {
433	my $nreq = 0;	592	$grp->result (\@dirs, \@nondirs);
		593	};
434		594
435	$schedcb = sub {	595	limit $statgrp $maxreq;
436	if (@$entries) {	596	feed $statgrp sub {
437	if ($nreq < $maxreq) {	597	return unless @$entries;
438	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	}
439	$nreq++;	618	}
440	aio_stat "$path/$ent/.", sub { $statcb->($_[0], $ent) };
441	}	619	}
442	} elsif (!$nreq) {
443	# finished
444	undef $statcb;
445	undef $schedcb;
446	$cb->(\@dirs, \@nondirs) if $cb;
447	undef $cb;
448	}	620	};
449	};	621	};
450	$statcb = sub {
451	my ($status, $entry) = @_;
452
453	if ($status < 0) {
454	$nreq--;
455	push @nondirs, $entry;
456	&$schedcb;
457	} else {
458	# need to check for real directory
459	aio_lstat "$path/$entry", sub {
460	$nreq--;
461
462	if (-d _) {
463	push @dirs, $entry;
464
465	if (!--$ndirs) {
466	push @nondirs, @$entries;
467	$entries = [];
468	}
469	} else {
470	push @nondirs, $entry;
471	}
472
473	&$schedcb;
474	}
475	}
476	};
477
478	&$schedcb while @$entries && $nreq < $maxreq;
479	};	622	};
480	};	623	};
481	};	624	};
		625
		626	$grp
482	}	627	}
483		628
484	=item aio_fsync $fh, $callback->($status)	629	=item aio_fsync $fh, $callback->($status)
485		630
486	Asynchronously call fsync on the given filehandle and call the callback	631	Asynchronously call fsync on the given filehandle and call the callback
…		…
492	callback with the fdatasync result code.	637	callback with the fdatasync result code.
493		638
494	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
495	detected, it will be emulated by calling C<fsync> instead.	640	detected, it will be emulated by calling C<fsync> instead.
496		641
		642	=item aio_group $callback->(...)
		643
		644	This is a very special aio request: Instead of doing something, it is a
		645	container for other aio requests, which is useful if you want to bundle
		646	many requests into a single, composite, request with a definite callback
		647	and the ability to cancel the whole request with its subrequests.
		648
		649	Returns an object of class L<IO::AIO::GRP>. See its documentation below
		650	for more info.
		651
		652	Example:
		653
		654	my $grp = aio_group sub {
		655	print "all stats done\n";
		656	};
		657
		658	add $grp
		659	(aio_stat ...),
		660	(aio_stat ...),
		661	...;
		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
		676	=item IO::AIO::aio_busy $fractional_seconds, $callback->() NOT EXPORTED
		677
		678	Mainly used for debugging and benchmarking, this aio request puts one of
		679	the request workers to sleep for the given time.
		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
497	=back	686	=back
498		687
499	=head2 IO::AIO::CB CLASS	688	=head2 IO::AIO::REQ CLASS
500		689
501	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
502	called in non-void context.	691	called in non-void context.
503		692
504	A request always moves through the following five states in its lifetime,
505	in order: B<ready> (request has been created, but has not been executed
506	yet), B<execute> (request is currently being executed), B<pending>
507	(request has been executed but callback has not been called yet),
508	B<result> (results are being processed synchronously, includes calling the
509	callback) and B<done> (request has reached the end of its lifetime and
510	holds no resources anymore).
511
512	=over 4	693	=over 4
513		694
514	=item $req->cancel	695	=item cancel $req
515		696
516	Cancels the request, if possible. Has the effect of skipping execution	697	Cancels the request, if possible. Has the effect of skipping execution
517	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
518	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
519	untouched. That means that requests that currently execute will not be	700	untouched. That means that requests that currently execute will not be
520	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.
521		702
		703	=item cb $req $callback->(...)
		704
		705	Replace (or simply set) the callback registered to the request.
		706
		707	=back
		708
		709	=head2 IO::AIO::GRP CLASS
		710
		711	This class is a subclass of L<IO::AIO::REQ>, so all its methods apply to
		712	objects of this class, too.
		713
		714	A IO::AIO::GRP object is a special request that can contain multiple other
		715	aio requests.
		716
		717	You create one by calling the C<aio_group> constructing function with a
		718	callback that will be called when all contained requests have entered the
		719	C<done> state:
		720
		721	my $grp = aio_group sub {
		722	print "all requests are done\n";
		723	};
		724
		725	You add requests by calling the C<add> method with one or more
		726	C<IO::AIO::REQ> objects:
		727
		728	$grp->add (aio_unlink "...");
		729
		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	};
		738
		739	This makes it very easy to create composite requests (see the source of
		740	C<aio_move> for an application) that work and feel like simple requests.
		741
		742	=over 4
		743
		744	=item * The IO::AIO::GRP objects will be cleaned up during calls to
		745	C<IO::AIO::poll_cb>, just like any other request.
		746
		747	=item * They can be canceled like any other request. Canceling will cancel not
		748	only the request itself, but also all requests it contains.
		749
		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
		756
		757	Their lifetime, simplified, looks like this: when they are empty, they
		758	will finish very quickly. If they contain only requests that are in the
		759	C<done> state, they will also finish. Otherwise they will continue to
		760	exist.
		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
		767	=over 4
		768
		769	=item add $grp ...
		770
		771	=item $grp->add (...)
		772
		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.
		776
		777	Returns all its arguments.
		778
		779	=item $grp->cancel_subs
		780
		781	Cancel all subrequests and clears any feeder, but not the group request
		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.
		845
522	=back	846	=back
523		847
524	=head2 SUPPORT FUNCTIONS	848	=head2 SUPPORT FUNCTIONS
525		849
526	=over 4	850	=over 4
…		…
538		862
539	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
540	regularly. Returns the number of events processed. Returns immediately	864	regularly. Returns the number of events processed. Returns immediately
541	when no events are outstanding.	865	when no events are outstanding.
542		866
		867	If not all requests were processed for whatever reason, the filehandle
		868	will still be ready when C<poll_cb> returns.
		869
543	Example: Install an Event watcher that automatically calls	870	Example: Install an Event watcher that automatically calls
544	IO::AIO::poll_cb with high priority:	871	IO::AIO::poll_cb with high priority:
545		872
546	Event->io (fd => IO::AIO::poll_fileno,	873	Event->io (fd => IO::AIO::poll_fileno,
547	poll => 'r', async => 1,	874	poll => 'r', async => 1,
548	cb => \&IO::AIO::poll_cb);	875	cb => \&IO::AIO::poll_cb);
549		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
550	=item IO::AIO::poll_wait	893	=item IO::AIO::poll_wait
551		894
552	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
553	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
554	for some requests to finish).	897	for some requests to finish).
555		898
556	See C<nreqs> for an example.	899	See C<nreqs> for an example.
557		900
558	=item IO::AIO::nreqs	901	=item IO::AIO::nreqs
559		902
560	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
561	callback has not been invoked yet).	904	states (i.e. for which their callback has not been invoked yet).
562		905
563	Example: wait till there are no outstanding requests anymore:	906	Example: wait till there are no outstanding requests anymore:
564		907
565	IO::AIO::poll_wait, IO::AIO::poll_cb	908	IO::AIO::poll_wait, IO::AIO::poll_cb
566	while IO::AIO::nreqs;	909	while IO::AIO::nreqs;
567		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
568	=item IO::AIO::flush	921	=item IO::AIO::flush
569		922
570	Wait till all outstanding AIO requests have been handled.	923	Wait till all outstanding AIO requests have been handled.
571		924
572	Strictly equivalent to:	925	Strictly equivalent to:
…		…
583	IO::AIO::poll_wait, IO::AIO::poll_cb	936	IO::AIO::poll_wait, IO::AIO::poll_cb
584	if IO::AIO::nreqs;	937	if IO::AIO::nreqs;
585		938
586	=item IO::AIO::min_parallel $nthreads	939	=item IO::AIO::min_parallel $nthreads
587		940
588	Set the minimum number of AIO threads to C<$nthreads>. The current default	941	Set the minimum number of AIO threads to C<$nthreads>. The current
589	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
590	(the number of outstanding operations, however, is unlimited).	943	concurrently at any one time (the number of outstanding requests,
		944	however, is unlimited).
591		945
592	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
593	no free thread exists.	947	no free thread exists.
594		948
595	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
596	kernel versions will scale negatively with the number of threads (higher	950	Linux kernel versions will scale negatively with the number of threads
597	parallelity => MUCH higher latency). With current Linux 2.6 versions, 4-32	951	(higher parallelity => MUCH higher latency). With current Linux 2.6
598	threads should be fine.	952	versions, 4-32 threads should be fine.
599		953
600	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
601	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.
602		956
603	=item IO::AIO::max_parallel $nthreads	957	=item IO::AIO::max_parallel $nthreads
…		…
612	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
613	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.
614		968
615	Under normal circumstances you don't need to call this function.	969	Under normal circumstances you don't need to call this function.
616		970
617	=item $oldnreqs = IO::AIO::max_outstanding $nreqs	971	=item $oldmaxreqs = IO::AIO::max_outstanding $maxreqs
		972
		973	This is a very bad function to use in interactive programs because it
		974	blocks, and a bad way to reduce concurrency because it is inexact: Better
		975	use an C<aio_group> together with a feed callback.
618		976
619	Sets the maximum number of outstanding requests to C<$nreqs>. If you	977	Sets the maximum number of outstanding requests to C<$nreqs>. If you
620	try to queue up more than this number of requests, the caller will block until	978	to queue up more than this number of requests, the next call to the
621	some requests have been handled.	979	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
		980	function will block until the limit is no longer exceeded.
622		981
623	The default is very large, so normally there is no practical limit. If you	982	The default value is very large, so there is no practical limit on the
624	queue up many requests in a loop it often improves speed if you set	983	number of outstanding requests.
625	this to a relatively low number, such as C<100>.
626		984
627	Under normal circumstances you don't need to call this function.	985	You can still queue as many requests as you want. Therefore,
		986	C<max_oustsanding> is mainly useful in simple scripts (with low values) or
		987	as a stop gap to shield against fatal memory overflow (with large values).
628		988
629	=back	989	=back
630		990
631	=cut	991	=cut
632		992
…		…
644	or return undef;	1004	or return undef;
645		1005
646	*$sym	1006	*$sym
647	}	1007	}
648		1008
649	min_parallel 4;	1009	min_parallel 8;
650		1010
651	END {	1011	END {
652	max_parallel 0;	1012	min_parallel 1;
653	}	1013	flush;
		1014	};
654		1015
655	1;	1016	1;
656		1017
657	=head2 FORK BEHAVIOUR	1018	=head2 FORK BEHAVIOUR
658		1019
659	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:
660		1021
661	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
662	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
663	the fork the parent simply leaves the quiescent state and continues	1024	the fork the parent simply leaves the quiescent state and continues
664	request/result processing, while the child clears the request/result	1025	request/result processing, while the child frees the request/result queue
665	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
666	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
667	parent process has been reached again.	1028	parent process has been reached again.
668		1029
669	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
670	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
671	yet.	1032	yet.
672		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
673	=head1 SEE ALSO	1057	=head1 SEE ALSO
674		1058
675	L<Coro>, L<Linux::AIO> (obsolete).	1059	L<Coro::AIO>.
676		1060
677	=head1 AUTHOR	1061	=head1 AUTHOR
678		1062
679	Marc Lehmann <schmorp@schmorp.de>	1063	Marc Lehmann <schmorp@schmorp.de>
680	http://home.schmorp.de/	1064	http://home.schmorp.de/

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Comparing IO-AIO/AIO.pm (file contents): Revision 1.52 by root, Sat Oct 21 23:06:04 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 1.52 by root, Sat Oct 21 23:06:04 2006 UTC vs.
Revision 1.85 by root, Sat Oct 28 01:40:30 2006 UTC