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

Comparing IO-AIO/AIO.pm (file contents):
Revision 1.53 by root, Sat Oct 21 23:20:29 2006 UTC vs.
Revision 1.83 by root, Fri Oct 27 20:11:58 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
52	Currently, a number of threads are started that execute your read/writes	56	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	57	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	58	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	59	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	60	functions available on many operating systems. However, they are often
57	not well-supported (Linux doesn't allow them on normal files currently,	61	not well-supported or restricted (Linux doesn't allow them on normal
58	for example), and they would only support aio_read and aio_write, so the	62	files currently, for example), and they would only support aio_read and
59	remaining functionality would have to be implemented using threads anyway.	63	aio_write, so the remaining functionality would have to be implemented
		64	using threads anyway.
60		65
61	Although the module will work with in the presence of other threads, it is	66	Although the module will work with in the presence of other (Perl-)
62	currently not reentrant, so use appropriate locking yourself, always call	67	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	68	locking yourself, always call C<poll_cb> from within the same thread, or
64	C<aio_> functions) recursively.	69	never call C<poll_cb> (or other C<aio_> functions) recursively.
		70
		71	=head1 REQUEST ANATOMY AND LIFETIME
		72
		73	Every C<aio_*> function creates a request. which is a C data structure not
		74	directly visible to Perl.
		75
		76	If called in non-void context, every request function returns a Perl
		77	object representing the request. In void context, nothing is returned,
		78	which saves a bit of memory.
		79
		80	The perl object is a fairly standard ref-to-hash object. The hash contents
		81	are not used by IO::AIO so you are free to store anything you like in it.
		82
		83	During their existance, aio requests travel through the following states,
		84	in order:
		85
		86	=over 4
		87
		88	=item ready
		89
		90	Immediately after a request is created it is put into the ready state,
		91	waiting for a thread to execute it.
		92
		93	=item execute
		94
		95	A thread has accepted the request for processing and is currently
		96	executing it (e.g. blocking in read).
		97
		98	=item pending
		99
		100	The request has been executed and is waiting for result processing.
		101
		102	While request submission and execution is fully asynchronous, result
		103	processing is not and relies on the perl interpreter calling C<poll_cb>
		104	(or another function with the same effect).
		105
		106	=item result
		107
		108	The request results are processed synchronously by C<poll_cb>.
		109
		110	The C<poll_cb> function will process all outstanding aio requests by
		111	calling their callbacks, freeing memory associated with them and managing
		112	any groups they are contained in.
		113
		114	=item done
		115
		116	Request has reached the end of its lifetime and holds no resources anymore
		117	(except possibly for the Perl object, but its connection to the actual
		118	aio request is severed and calling its methods will either do nothing or
		119	result in a runtime error).
65		120
66	=cut	121	=cut
67		122
68	package IO::AIO;	123	package IO::AIO;
69		124
…		…
71	use strict 'vars';	126	use strict 'vars';
72		127
73	use base 'Exporter';	128	use base 'Exporter';
74		129
75	BEGIN {	130	BEGIN {
76	our $VERSION = '1.99';	131	our $VERSION = '2.0';
77		132
78	our @EXPORT = qw(aio_sendfile aio_read aio_write aio_open aio_close aio_stat	133	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	134	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);	135	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);	136	aio_copy aio_group aio_nop aio_mknod);
		137	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
		138	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
		139	min_parallel max_parallel nreqs nready npending);
		140
		141	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';
82		142
83	require XSLoader;	143	require XSLoader;
84	XSLoader::load ("IO::AIO", $VERSION);	144	XSLoader::load ("IO::AIO", $VERSION);
85	}	145	}
86		146
…		…
97	syscall has been executed asynchronously.	157	syscall has been executed asynchronously.
98		158
99	All functions expecting a filehandle keep a copy of the filehandle	159	All functions expecting a filehandle keep a copy of the filehandle
100	internally until the request has finished.	160	internally until the request has finished.
101		161
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	162	All requests return objects of type L<IO::AIO::REQ> that allow further
104	further manipulation of running requests.	163	manipulation of those requests while they are in-flight.
105		164
106	The pathnames you pass to these routines I<must> be absolute and	165	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	166	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	167	request is being executed, the current working directory could have
109	changed. Alternatively, you can make sure that you never change the	168	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	174	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)	175	environment, d) use Glib::filename_from_unicode on unicode filenames or e)
117	use something else.	176	use something else.
118		177
119	=over 4	178	=over 4
		179
		180	=item $prev_pri = aioreq_pri [$pri]
		181
		182	Returns the priority value that would be used for the next request and, if
		183	C<$pri> is given, sets the priority for the next aio request.
		184
		185	The default priority is C<0>, the minimum and maximum priorities are C<-4>
		186	and C<4>, respectively. Requests with higher priority will be serviced
		187	first.
		188
		189	The priority will be reset to C<0> after each call to one of the C<aio_*>
		190	functions.
		191
		192	Example: open a file with low priority, then read something from it with
		193	higher priority so the read request is serviced before other low priority
		194	open requests (potentially spamming the cache):
		195
		196	aioreq_pri -3;
		197	aio_open ..., sub {
		198	return unless $_[0];
		199
		200	aioreq_pri -2;
		201	aio_read $_[0], ..., sub {
		202	...
		203	};
		204	};
		205
		206	=item aioreq_nice $pri_adjust
		207
		208	Similar to C<aioreq_pri>, but subtracts the given value from the current
		209	priority, so effects are cumulative.
120		210
121	=item aio_open $pathname, $flags, $mode, $callback->($fh)	211	=item aio_open $pathname, $flags, $mode, $callback->($fh)
122		212
123	Asynchronously open or create a file and call the callback with a newly	213	Asynchronously open or create a file and call the callback with a newly
124	created filehandle for the file.	214	created filehandle for the file.
…		…
174		264
175	aio_read $fh, 7, 15, $buffer, 0, sub {	265	aio_read $fh, 7, 15, $buffer, 0, sub {
176	$_[0] > 0 or die "read error: $!";	266	$_[0] > 0 or die "read error: $!";
177	print "read $_[0] bytes: <$buffer>\n";	267	print "read $_[0] bytes: <$buffer>\n";
178	};	268	};
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		269
244	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)	270	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
245		271
246	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts	272	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	273	reading at byte offset C<$in_offset>, and starts writing at the current
…		…
303	=item aio_unlink $pathname, $callback->($status)	329	=item aio_unlink $pathname, $callback->($status)
304		330
305	Asynchronously unlink (delete) a file and call the callback with the	331	Asynchronously unlink (delete) a file and call the callback with the
306	result code.	332	result code.
307		333
		334	=item aio_mknod $path, $mode, $dev, $callback->($status)
		335
		336	Asynchronously create a device node (or fifo). See mknod(2).
		337
		338	The only portable (POSIX) way of calling this function is:
		339
		340	aio_mknod $path, IO::AIO::S_IFIFO \| $mode, 0, sub { ...
		341
308	=item aio_link $srcpath, $dstpath, $callback->($status)	342	=item aio_link $srcpath, $dstpath, $callback->($status)
309		343
310	Asynchronously create a new link to the existing object at C<$srcpath> at	344	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.	345	the path C<$dstpath> and call the callback with the result code.
312		346
…		…
332	sorted, and will B<NOT> include the C<.> and C<..> entries.	366	sorted, and will B<NOT> include the C<.> and C<..> entries.
333		367
334	The callback a single argument which is either C<undef> or an array-ref	368	The callback a single argument which is either C<undef> or an array-ref
335	with the filenames.	369	with the filenames.
336		370
		371	=item aio_copy $srcpath, $dstpath, $callback->($status)
		372
		373	Try to copy the I<file> (directories not supported as either source or
		374	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		375	the C<0> (error) or C<-1> ok.
		376
		377	This is a composite request that it creates the destination file with
		378	mode 0200 and copies the contents of the source file into it using
		379	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
		380	uid/gid, in that order.
		381
		382	If an error occurs, the partial destination file will be unlinked, if
		383	possible, except when setting atime, mtime, access mode and uid/gid, where
		384	errors are being ignored.
		385
		386	=cut
		387
		388	sub aio_copy($$;$) {
		389	my ($src, $dst, $cb) = @_;
		390
		391	my $pri = aioreq_pri;
		392	my $grp = aio_group $cb;
		393
		394	aioreq_pri $pri;
		395	add $grp aio_open $src, O_RDONLY, 0, sub {
		396	if (my $src_fh = $_[0]) {
		397	my @stat = stat $src_fh;
		398
		399	aioreq_pri $pri;
		400	add $grp aio_open $dst, O_CREAT \| O_WRONLY \| O_TRUNC, 0200, sub {
		401	if (my $dst_fh = $_[0]) {
		402	aioreq_pri $pri;
		403	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
		404	if ($_[0] == $stat[7]) {
		405	$grp->result (0);
		406	close $src_fh;
		407
		408	# those should not normally block. should. should.
		409	utime $stat[8], $stat[9], $dst;
		410	chmod $stat[2] & 07777, $dst_fh;
		411	chown $stat[4], $stat[5], $dst_fh;
		412	close $dst_fh;
		413	} else {
		414	$grp->result (-1);
		415	close $src_fh;
		416	close $dst_fh;
		417
		418	aioreq $pri;
		419	add $grp aio_unlink $dst;
		420	}
		421	};
		422	} else {
		423	$grp->result (-1);
		424	}
		425	},
		426
		427	} else {
		428	$grp->result (-1);
		429	}
		430	};
		431
		432	$grp
		433	}
		434
		435	=item aio_move $srcpath, $dstpath, $callback->($status)
		436
		437	Try to move 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 tries to rename(2) the file first. If
		442	rename files with C<EXDEV>, it copies the file with C<aio_copy> and, if
		443	that is successful, unlinking the C<$srcpath>.
		444
		445	=cut
		446
		447	sub aio_move($$;$) {
		448	my ($src, $dst, $cb) = @_;
		449
		450	my $pri = aioreq_pri;
		451	my $grp = aio_group $cb;
		452
		453	aioreq_pri $pri;
		454	add $grp aio_rename $src, $dst, sub {
		455	if ($_[0] && $! == EXDEV) {
		456	aioreq_pri $pri;
		457	add $grp aio_copy $src, $dst, sub {
		458	$grp->result ($_[0]);
		459
		460	if (!$_[0]) {
		461	aioreq_pri $pri;
		462	add $grp aio_unlink $src;
		463	}
		464	};
		465	} else {
		466	$grp->result ($_[0]);
		467	}
		468	};
		469
		470	$grp
		471	}
		472
337	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	473	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
338		474
339	Scans a directory (similar to C<aio_readdir>) but additionally tries to	475	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	476	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	477	names, directories you can recurse into (directories), and ones you cannot
342	recurse into (everything else).	478	recurse into (everything else, including symlinks to directories).
343		479
344	C<aio_scandir> is a composite request that consists of many sub	480	C<aio_scandir> is a composite request that creates of many sub requests_
345	requests. C<$maxreq> specifies the maximum number of outstanding aio	481	C<$maxreq> specifies the maximum number of outstanding aio requests that
346	requests that this function generates. If it is C<< <= 0 >>, then a	482	this function generates. If it is C<< <= 0 >>, then a suitable default
347	suitable default will be chosen (currently 8).	483	will be chosen (currently 4).
348		484
349	On error, the callback is called without arguments, otherwise it receives	485	On error, the callback is called without arguments, otherwise it receives
350	two array-refs with path-relative entry names.	486	two array-refs with path-relative entry names.
351		487
352	Example:	488	Example:
…		…
389	=cut	525	=cut
390		526
391	sub aio_scandir($$$) {	527	sub aio_scandir($$$) {
392	my ($path, $maxreq, $cb) = @_;	528	my ($path, $maxreq, $cb) = @_;
393		529
		530	my $pri = aioreq_pri;
		531
		532	my $grp = aio_group $cb;
		533
394	$maxreq = 8 if $maxreq <= 0;	534	$maxreq = 4 if $maxreq <= 0;
395		535
396	# stat once	536	# stat once
		537	aioreq_pri $pri;
397	aio_stat $path, sub {	538	add $grp aio_stat $path, sub {
398	return $cb->() if $_[0];	539	return $grp->result () if $_[0];
399	my $now = time;	540	my $now = time;
400	my $hash1 = join ":", (stat _)[0,1,3,7,9];	541	my $hash1 = join ":", (stat _)[0,1,3,7,9];
401		542
402	# read the directory entries	543	# read the directory entries
		544	aioreq_pri $pri;
403	aio_readdir $path, sub {	545	add $grp aio_readdir $path, sub {
404	my $entries = shift	546	my $entries = shift
405	or return $cb->();	547	or return $grp->result ();
406		548
407	# stat the dir another time	549	# stat the dir another time
		550	aioreq_pri $pri;
408	aio_stat $path, sub {	551	add $grp aio_stat $path, sub {
409	my $hash2 = join ":", (stat _)[0,1,3,7,9];	552	my $hash2 = join ":", (stat _)[0,1,3,7,9];
410		553
411	my $ndirs;	554	my $ndirs;
412		555
413	# take the slow route if anything looks fishy	556	# take the slow route if anything looks fishy
…		…
415	$ndirs = -1;	558	$ndirs = -1;
416	} else {	559	} else {
417	# if nlink == 2, we are finished	560	# if nlink == 2, we are finished
418	# on non-posix-fs's, we rely on nlink < 2	561	# on non-posix-fs's, we rely on nlink < 2
419	$ndirs = (stat _)[3] - 2	562	$ndirs = (stat _)[3] - 2
420	or return $cb->([], $entries);	563	or return $grp->result ([], $entries);
421	}	564	}
422		565
423	# sort into likely dirs and likely nondirs	566	# sort into likely dirs and likely nondirs
424	# dirs == files without ".", short entries first	567	# dirs == files without ".", short entries first
425	$entries = [map $_->[0],	568	$entries = [map $_->[0],
…		…
427	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],	570	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
428	@$entries];	571	@$entries];
429		572
430	my (@dirs, @nondirs);	573	my (@dirs, @nondirs);
431		574
432	my ($statcb, $schedcb);	575	my $statgrp = add $grp aio_group sub {
433	my $nreq = 0;	576	$grp->result (\@dirs, \@nondirs);
		577	};
434		578
435	$schedcb = sub {	579	limit $statgrp $maxreq;
436	if (@$entries) {	580	feed $statgrp sub {
437	if ($nreq < $maxreq) {	581	return unless @$entries;
438	my $ent = pop @$entries;	582	my $entry = pop @$entries;
		583
		584	aioreq_pri $pri;
		585	add $statgrp aio_stat "$path/$entry/.", sub {
		586	if ($_[0] < 0) {
		587	push @nondirs, $entry;
		588	} else {
		589	# need to check for real directory
		590	aioreq_pri $pri;
		591	add $statgrp aio_lstat "$path/$entry", sub {
		592	if (-d _) {
		593	push @dirs, $entry;
		594
		595	unless (--$ndirs) {
		596	push @nondirs, @$entries;
		597	feed $statgrp;
		598	}
		599	} else {
		600	push @nondirs, $entry;
		601	}
439	$nreq++;	602	}
440	aio_stat "$path/$ent/.", sub { $statcb->($_[0], $ent) };
441	}	603	}
442	} elsif (!$nreq) {
443	# finished
444	undef $statcb;
445	undef $schedcb;
446	$cb->(\@dirs, \@nondirs) if $cb;
447	undef $cb;
448	}	604	};
449	};	605	};
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	};	606	};
480	};	607	};
481	};	608	};
		609
		610	$grp
482	}	611	}
483		612
484	=item aio_fsync $fh, $callback->($status)	613	=item aio_fsync $fh, $callback->($status)
485		614
486	Asynchronously call fsync on the given filehandle and call the callback	615	Asynchronously call fsync on the given filehandle and call the callback
…		…
492	callback with the fdatasync result code.	621	callback with the fdatasync result code.
493		622
494	If this call isn't available because your OS lacks it or it couldn't be	623	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.	624	detected, it will be emulated by calling C<fsync> instead.
496		625
		626	=item aio_group $callback->(...)
		627
		628	This is a very special aio request: Instead of doing something, it is a
		629	container for other aio requests, which is useful if you want to bundle
		630	many requests into a single, composite, request with a definite callback
		631	and the ability to cancel the whole request with its subrequests.
		632
		633	Returns an object of class L<IO::AIO::GRP>. See its documentation below
		634	for more info.
		635
		636	Example:
		637
		638	my $grp = aio_group sub {
		639	print "all stats done\n";
		640	};
		641
		642	add $grp
		643	(aio_stat ...),
		644	(aio_stat ...),
		645	...;
		646
		647	=item aio_nop $callback->()
		648
		649	This is a special request - it does nothing in itself and is only used for
		650	side effects, such as when you want to add a dummy request to a group so
		651	that finishing the requests in the group depends on executing the given
		652	code.
		653
		654	While this request does nothing, it still goes through the execution
		655	phase and still requires a worker thread. Thus, the callback will not
		656	be executed immediately but only after other requests in the queue have
		657	entered their execution phase. This can be used to measure request
		658	latency.
		659
		660	=item IO::AIO::aio_busy $fractional_seconds, $callback->() NOT EXPORTED
		661
		662	Mainly used for debugging and benchmarking, this aio request puts one of
		663	the request workers to sleep for the given time.
		664
		665	While it is theoretically handy to have simple I/O scheduling requests
		666	like sleep and file handle readable/writable, the overhead this creates is
		667	immense (it blocks a thread for a long time) so do not use this function
		668	except to put your application under artificial I/O pressure.
		669
497	=back	670	=back
498		671
499	=head2 IO::AIO::REQ CLASS	672	=head2 IO::AIO::REQ CLASS
500		673
501	All non-aggregate C<aio_*> functions return an object of this class when	674	All non-aggregate C<aio_*> functions return an object of this class when
502	called in non-void context.	675	called in non-void context.
503		676
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	677	=over 4
513		678
514	=item $req->cancel	679	=item cancel $req
515		680
516	Cancels the request, if possible. Has the effect of skipping execution	681	Cancels the request, if possible. Has the effect of skipping execution
517	when entering the B<execute> state and skipping calling the callback when	682	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	683	entering the the B<result> state, but will leave the request otherwise
519	untouched. That means that requests that currently execute will not be	684	untouched. That means that requests that currently execute will not be
520	stopped and resources held by the request will not be freed prematurely.	685	stopped and resources held by the request will not be freed prematurely.
521		686
		687	=item cb $req $callback->(...)
		688
		689	Replace (or simply set) the callback registered to the request.
		690
		691	=back
		692
		693	=head2 IO::AIO::GRP CLASS
		694
		695	This class is a subclass of L<IO::AIO::REQ>, so all its methods apply to
		696	objects of this class, too.
		697
		698	A IO::AIO::GRP object is a special request that can contain multiple other
		699	aio requests.
		700
		701	You create one by calling the C<aio_group> constructing function with a
		702	callback that will be called when all contained requests have entered the
		703	C<done> state:
		704
		705	my $grp = aio_group sub {
		706	print "all requests are done\n";
		707	};
		708
		709	You add requests by calling the C<add> method with one or more
		710	C<IO::AIO::REQ> objects:
		711
		712	$grp->add (aio_unlink "...");
		713
		714	add $grp aio_stat "...", sub {
		715	$_[0] or return $grp->result ("error");
		716
		717	# add another request dynamically, if first succeeded
		718	add $grp aio_open "...", sub {
		719	$grp->result ("ok");
		720	};
		721	};
		722
		723	This makes it very easy to create composite requests (see the source of
		724	C<aio_move> for an application) that work and feel like simple requests.
		725
		726	=over 4
		727
		728	=item * The IO::AIO::GRP objects will be cleaned up during calls to
		729	C<IO::AIO::poll_cb>, just like any other request.
		730
		731	=item * They can be canceled like any other request. Canceling will cancel not
		732	only the request itself, but also all requests it contains.
		733
		734	=item * They can also can also be added to other IO::AIO::GRP objects.
		735
		736	=item * You must not add requests to a group from within the group callback (or
		737	any later time).
		738
		739	=back
		740
		741	Their lifetime, simplified, looks like this: when they are empty, they
		742	will finish very quickly. If they contain only requests that are in the
		743	C<done> state, they will also finish. Otherwise they will continue to
		744	exist.
		745
		746	That means after creating a group you have some time to add requests. And
		747	in the callbacks of those requests, you can add further requests to the
		748	group. And only when all those requests have finished will the the group
		749	itself finish.
		750
		751	=over 4
		752
		753	=item add $grp ...
		754
		755	=item $grp->add (...)
		756
		757	Add one or more requests to the group. Any type of L<IO::AIO::REQ> can
		758	be added, including other groups, as long as you do not create circular
		759	dependencies.
		760
		761	Returns all its arguments.
		762
		763	=item $grp->cancel_subs
		764
		765	Cancel all subrequests and clears any feeder, but not the group request
		766	itself. Useful when you queued a lot of events but got a result early.
		767
		768	=item $grp->result (...)
		769
		770	Set the result value(s) that will be passed to the group callback when all
		771	subrequests have finished and set thre groups errno to the current value
		772	of errno (just like calling C<errno> without an error number). By default,
		773	no argument will be passed and errno is zero.
		774
		775	=item $grp->errno ([$errno])
		776
		777	Sets the group errno value to C<$errno>, or the current value of errno
		778	when the argument is missing.
		779
		780	Every aio request has an associated errno value that is restored when
		781	the callback is invoked. This method lets you change this value from its
		782	default (0).
		783
		784	Calling C<result> will also set errno, so make sure you either set C<$!>
		785	before the call to C<result>, or call c<errno> after it.
		786
		787	=item feed $grp $callback->($grp)
		788
		789	Sets a feeder/generator on this group: every group can have an attached
		790	generator that generates requests if idle. The idea behind this is that,
		791	although you could just queue as many requests as you want in a group,
		792	this might starve other requests for a potentially long time. For
		793	example, C<aio_scandir> might generate hundreds of thousands C<aio_stat>
		794	requests, delaying any later requests for a long time.
		795
		796	To avoid this, and allow incremental generation of requests, you can
		797	instead a group and set a feeder on it that generates those requests. The
		798	feed callback will be called whenever there are few enough (see C<limit>,
		799	below) requests active in the group itself and is expected to queue more
		800	requests.
		801
		802	The feed callback can queue as many requests as it likes (i.e. C<add> does
		803	not impose any limits).
		804
		805	If the feed does not queue more requests when called, it will be
		806	automatically removed from the group.
		807
		808	If the feed limit is C<0>, it will be set to C<2> automatically.
		809
		810	Example:
		811
		812	# stat all files in @files, but only ever use four aio requests concurrently:
		813
		814	my $grp = aio_group sub { print "finished\n" };
		815	limit $grp 4;
		816	feed $grp sub {
		817	my $file = pop @files
		818	or return;
		819
		820	add $grp aio_stat $file, sub { ... };
		821	};
		822
		823	=item limit $grp $num
		824
		825	Sets the feeder limit for the group: The feeder will be called whenever
		826	the group contains less than this many requests.
		827
		828	Setting the limit to C<0> will pause the feeding process.
		829
522	=back	830	=back
523		831
524	=head2 SUPPORT FUNCTIONS	832	=head2 SUPPORT FUNCTIONS
525		833
526	=over 4	834	=over 4
…		…
538		846
539	Process all outstanding events on the result pipe. You have to call this	847	Process all outstanding events on the result pipe. You have to call this
540	regularly. Returns the number of events processed. Returns immediately	848	regularly. Returns the number of events processed. Returns immediately
541	when no events are outstanding.	849	when no events are outstanding.
542		850
		851	If not all requests were processed for whatever reason, the filehandle
		852	will still be ready when C<poll_cb> returns.
		853
543	Example: Install an Event watcher that automatically calls	854	Example: Install an Event watcher that automatically calls
544	IO::AIO::poll_cb with high priority:	855	IO::AIO::poll_cb with high priority:
545		856
546	Event->io (fd => IO::AIO::poll_fileno,	857	Event->io (fd => IO::AIO::poll_fileno,
547	poll => 'r', async => 1,	858	poll => 'r', async => 1,
548	cb => \&IO::AIO::poll_cb);	859	cb => \&IO::AIO::poll_cb);
549		860
		861	=item IO::AIO::poll_some $max_requests
		862
		863	Similar to C<poll_cb>, but only processes up to C<$max_requests> requests
		864	at a time.
		865
		866	Useful if you want to ensure some level of interactiveness when perl is
		867	not fast enough to process all requests in time.
		868
		869	Example: Install an Event watcher that automatically calls
		870	IO::AIO::poll_some with low priority, to ensure that other parts of the
		871	program get the CPU sometimes even under high AIO load.
		872
		873	Event->io (fd => IO::AIO::poll_fileno,
		874	poll => 'r', nice => 1,
		875	cb => sub { IO::AIO::poll_some 256 });
		876
550	=item IO::AIO::poll_wait	877	=item IO::AIO::poll_wait
551		878
552	Wait till the result filehandle becomes ready for reading (simply does a	879	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	880	C<select> on the filehandle. This is useful if you want to synchronously wait
554	for some requests to finish).	881	for some requests to finish).
555		882
556	See C<nreqs> for an example.	883	See C<nreqs> for an example.
557		884
558	=item IO::AIO::nreqs	885	=item IO::AIO::nreqs
559		886
560	Returns the number of requests currently outstanding (i.e. for which their	887	Returns the number of requests currently in the ready, execute or pending
561	callback has not been invoked yet).	888	states (i.e. for which their callback has not been invoked yet).
562		889
563	Example: wait till there are no outstanding requests anymore:	890	Example: wait till there are no outstanding requests anymore:
564		891
565	IO::AIO::poll_wait, IO::AIO::poll_cb	892	IO::AIO::poll_wait, IO::AIO::poll_cb
566	while IO::AIO::nreqs;	893	while IO::AIO::nreqs;
567		894
		895	=item IO::AIO::nready
		896
		897	Returns the number of requests currently in the ready state (not yet
		898	executed).
		899
		900	=item IO::AIO::npending
		901
		902	Returns the number of requests currently in the pending state (executed,
		903	but not yet processed by poll_cb).
		904
568	=item IO::AIO::flush	905	=item IO::AIO::flush
569		906
570	Wait till all outstanding AIO requests have been handled.	907	Wait till all outstanding AIO requests have been handled.
571		908
572	Strictly equivalent to:	909	Strictly equivalent to:
…		…
583	IO::AIO::poll_wait, IO::AIO::poll_cb	920	IO::AIO::poll_wait, IO::AIO::poll_cb
584	if IO::AIO::nreqs;	921	if IO::AIO::nreqs;
585		922
586	=item IO::AIO::min_parallel $nthreads	923	=item IO::AIO::min_parallel $nthreads
587		924
588	Set the minimum number of AIO threads to C<$nthreads>. The current default	925	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	926	default is C<8>, which means eight asynchronous operations can execute
590	(the number of outstanding operations, however, is unlimited).	927	concurrently at any one time (the number of outstanding requests,
		928	however, is unlimited).
591		929
592	IO::AIO starts threads only on demand, when an AIO request is queued and	930	IO::AIO starts threads only on demand, when an AIO request is queued and
593	no free thread exists.	931	no free thread exists.
594		932
595	It is recommended to keep the number of threads low, as some Linux	933	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	934	Linux kernel versions will scale negatively with the number of threads
597	parallelity => MUCH higher latency). With current Linux 2.6 versions, 4-32	935	(higher parallelity => MUCH higher latency). With current Linux 2.6
598	threads should be fine.	936	versions, 4-32 threads should be fine.
599		937
600	Under most circumstances you don't need to call this function, as the	938	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.	939	module selects a default that is suitable for low to moderate load.
602		940
603	=item IO::AIO::max_parallel $nthreads	941	=item IO::AIO::max_parallel $nthreads
…		…
612	This module automatically runs C<max_parallel 0> at program end, to ensure	950	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.	951	that all threads are killed and that there are no outstanding requests.
614		952
615	Under normal circumstances you don't need to call this function.	953	Under normal circumstances you don't need to call this function.
616		954
617	=item $oldnreqs = IO::AIO::max_outstanding $nreqs	955	=item $oldmaxreqs = IO::AIO::max_outstanding $maxreqs
		956
		957	This is a very bad function to use in interactive programs because it
		958	blocks, and a bad way to reduce concurrency because it is inexact: Better
		959	use an C<aio_group> together with a feed callback.
618		960
619	Sets the maximum number of outstanding requests to C<$nreqs>. If you	961	Sets the maximum number of outstanding requests to C<$nreqs>. If you
620	try to queue up more than this number of requests, the caller will block until	962	to queue up more than this number of requests, the next call to the
621	some requests have been handled.	963	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
		964	function will block until the limit is no longer exceeded.
622		965
623	The default is very large, so normally there is no practical limit. If you	966	The default value is very large, so there is no practical limit on the
624	queue up many requests in a loop it often improves speed if you set	967	number of outstanding requests.
625	this to a relatively low number, such as C<100>.
626		968
627	Under normal circumstances you don't need to call this function.	969	You can still queue as many requests as you want. Therefore,
		970	C<max_oustsanding> is mainly useful in simple scripts (with low values) or
		971	as a stop gap to shield against fatal memory overflow (with large values).
628		972
629	=back	973	=back
630		974
631	=cut	975	=cut
632		976
…		…
644	or return undef;	988	or return undef;
645		989
646	*$sym	990	*$sym
647	}	991	}
648		992
649	min_parallel 4;	993	min_parallel 8;
650		994
651	END {	995	END {
652	max_parallel 0;	996	flush;
653	}	997	};
654		998
655	1;	999	1;
656		1000
657	=head2 FORK BEHAVIOUR	1001	=head2 FORK BEHAVIOUR
658		1002
659	This module should do "the right thing" when the process using it forks:	1003	This module should do "the right thing" when the process using it forks:
660		1004
661	Before the fork, IO::AIO enters a quiescent state where no requests	1005	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	1006	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	1007	the fork the parent simply leaves the quiescent state and continues
664	request/result processing, while the child clears the request/result	1008	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	1009	(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	1010	parent). Threads will be started on demand until the limit set in the
667	parent process has been reached again.	1011	parent process has been reached again.
668		1012
669	In short: the parent will, after a short pause, continue as if fork had	1013	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	1014	not been called, while the child will act as if IO::AIO has not been used
671	yet.	1015	yet.
672		1016
		1017	=head2 MEMORY USAGE
		1018
		1019	Per-request usage:
		1020
		1021	Each aio request uses - depending on your architecture - around 100-200
		1022	bytes of memory. In addition, stat requests need a stat buffer (possibly
		1023	a few hundred bytes), readdir requires a result buffer and so on. Perl
		1024	scalars and other data passed into aio requests will also be locked and
		1025	will consume memory till the request has entered the done state.
		1026
		1027	This is now awfully much, so queuing lots of requests is not usually a
		1028	problem.
		1029
		1030	Per-thread usage:
		1031
		1032	In the execution phase, some aio requests require more memory for
		1033	temporary buffers, and each thread requires a stack and other data
		1034	structures (usually around 16k-128k, depending on the OS).
		1035
		1036	=head1 KNOWN BUGS
		1037
		1038	Known bugs will be fixed in the next release.
		1039
673	=head1 SEE ALSO	1040	=head1 SEE ALSO
674		1041
675	L<Coro>, L<Linux::AIO> (obsolete).	1042	L<Coro::AIO>.
676		1043
677	=head1 AUTHOR	1044	=head1 AUTHOR
678		1045
679	Marc Lehmann <schmorp@schmorp.de>	1046	Marc Lehmann <schmorp@schmorp.de>
680	http://home.schmorp.de/	1047	http://home.schmorp.de/

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Comparing IO-AIO/AIO.pm (file contents): Revision 1.53 by root, Sat Oct 21 23:20:29 2006 UTC vs. Revision 1.83 by root, Fri Oct 27 20:11:58 2006 UTC

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Comparing IO-AIO/AIO.pm (file contents):
Revision 1.53 by root, Sat Oct 21 23:20:29 2006 UTC vs.
Revision 1.83 by root, Fri Oct 27 20:11:58 2006 UTC