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

Comparing IO-AIO/AIO.pm (file contents):
Revision 1.54 by root, Sun Oct 22 00:19:05 2006 UTC vs.
Revision 1.82 by root, Fri Oct 27 20:10:06 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	aio_group);	136	aio_copy aio_group aio_nop aio_mknod);
82	our @EXPORT_OK = qw(poll_fileno poll_cb min_parallel max_parallel max_outstanding nreqs);	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);
83		140
84	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';	141	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';
85		142
86	require XSLoader;	143	require XSLoader;
87	XSLoader::load ("IO::AIO", $VERSION);	144	XSLoader::load ("IO::AIO", $VERSION);
…		…
100	syscall has been executed asynchronously.	157	syscall has been executed asynchronously.
101		158
102	All functions expecting a filehandle keep a copy of the filehandle	159	All functions expecting a filehandle keep a copy of the filehandle
103	internally until the request has finished.	160	internally until the request has finished.
104		161
105	All non-composite requests (requests that are not broken down into
106	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
107	further manipulation of running requests.	163	manipulation of those requests while they are in-flight.
108		164
109	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
110	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
111	request is being executed, the current working directory could have	167	request is being executed, the current working directory could have
112	changed. Alternatively, you can make sure that you never change the	168	changed. Alternatively, you can make sure that you never change the
…		…
118	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
119	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)
120	use something else.	176	use something else.
121		177
122	=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.
123		210
124	=item aio_open $pathname, $flags, $mode, $callback->($fh)	211	=item aio_open $pathname, $flags, $mode, $callback->($fh)
125		212
126	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
127	created filehandle for the file.	214	created filehandle for the file.
…		…
177		264
178	aio_read $fh, 7, 15, $buffer, 0, sub {	265	aio_read $fh, 7, 15, $buffer, 0, sub {
179	$_[0] > 0 or die "read error: $!";	266	$_[0] > 0 or die "read error: $!";
180	print "read $_[0] bytes: <$buffer>\n";	267	print "read $_[0] bytes: <$buffer>\n";
181	};	268	};
182
183	=item aio_move $srcpath, $dstpath, $callback->($status)
184
185	Try to move the I<file> (directories not supported as either source or
186	destination) from C<$srcpath> to C<$dstpath> and call the callback with
187	the C<0> (error) or C<-1> ok.
188
189	This is a composite request that tries to rename(2) the file first. If
190	rename files with C<EXDEV>, it creates the destination file with mode 0200
191	and copies the contents of the source file into it using C<aio_sendfile>,
192	followed by restoring atime, mtime, access mode and uid/gid, in that
193	order, and unlinking the C<$srcpath>.
194
195	If an error occurs, the partial destination file will be unlinked, if
196	possible, except when setting atime, mtime, access mode and uid/gid, where
197	errors are being ignored.
198
199	=cut
200
201	sub aio_move($$$) {
202	my ($src, $dst, $cb) = @_;
203
204	aio_rename $src, $dst, sub {
205	if ($_[0] && $! == EXDEV) {
206	aio_open $src, O_RDONLY, 0, sub {
207	if (my $src_fh = $_[0]) {
208	my @stat = stat $src_fh;
209
210	aio_open $dst, O_WRONLY, 0200, sub {
211	if (my $dst_fh = $_[0]) {
212	aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
213	close $src_fh;
214
215	if ($_[0] == $stat[7]) {
216	utime $stat[8], $stat[9], $dst;
217	chmod $stat[2] & 07777, $dst_fh;
218	chown $stat[4], $stat[5], $dst_fh;
219	close $dst_fh;
220
221	aio_unlink $src, sub {
222	$cb->($_[0]);
223	};
224	} else {
225	my $errno = $!;
226	aio_unlink $dst, sub {
227	$! = $errno;
228	$cb->(-1);
229	};
230	}
231	};
232	} else {
233	$cb->(-1);
234	}
235	},
236
237	} else {
238	$cb->(-1);
239	}
240	};
241	} else {
242	$cb->($_[0]);
243	}
244	};
245	}
246		269
247	=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)
248		271
249	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
250	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
…		…
306	=item aio_unlink $pathname, $callback->($status)	329	=item aio_unlink $pathname, $callback->($status)
307		330
308	Asynchronously unlink (delete) a file and call the callback with the	331	Asynchronously unlink (delete) a file and call the callback with the
309	result code.	332	result code.
310		333
		334	=item aio_mknod $path, $mode, $dev, $callback->($status)
		335
		336	Asynchronously create a device node (or fifo). See mknod(2): the only
		337	portable value for C<$mode> is C<S_IFIFO> ored with permissions, and C<0>
		338	for C<$dev>.
		339
311	=item aio_link $srcpath, $dstpath, $callback->($status)	340	=item aio_link $srcpath, $dstpath, $callback->($status)
312		341
313	Asynchronously create a new link to the existing object at C<$srcpath> at	342	Asynchronously create a new link to the existing object at C<$srcpath> at
314	the path C<$dstpath> and call the callback with the result code.	343	the path C<$dstpath> and call the callback with the result code.
315		344
…		…
335	sorted, and will B<NOT> include the C<.> and C<..> entries.	364	sorted, and will B<NOT> include the C<.> and C<..> entries.
336		365
337	The callback a single argument which is either C<undef> or an array-ref	366	The callback a single argument which is either C<undef> or an array-ref
338	with the filenames.	367	with the filenames.
339		368
		369	=item aio_copy $srcpath, $dstpath, $callback->($status)
		370
		371	Try to copy the I<file> (directories not supported as either source or
		372	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		373	the C<0> (error) or C<-1> ok.
		374
		375	This is a composite request that it creates the destination file with
		376	mode 0200 and copies the contents of the source file into it using
		377	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
		378	uid/gid, in that order.
		379
		380	If an error occurs, the partial destination file will be unlinked, if
		381	possible, except when setting atime, mtime, access mode and uid/gid, where
		382	errors are being ignored.
		383
		384	=cut
		385
		386	sub aio_copy($$;$) {
		387	my ($src, $dst, $cb) = @_;
		388
		389	my $pri = aioreq_pri;
		390	my $grp = aio_group $cb;
		391
		392	aioreq_pri $pri;
		393	add $grp aio_open $src, O_RDONLY, 0, sub {
		394	if (my $src_fh = $_[0]) {
		395	my @stat = stat $src_fh;
		396
		397	aioreq_pri $pri;
		398	add $grp aio_open $dst, O_CREAT \| O_WRONLY \| O_TRUNC, 0200, sub {
		399	if (my $dst_fh = $_[0]) {
		400	aioreq_pri $pri;
		401	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
		402	if ($_[0] == $stat[7]) {
		403	$grp->result (0);
		404	close $src_fh;
		405
		406	# those should not normally block. should. should.
		407	utime $stat[8], $stat[9], $dst;
		408	chmod $stat[2] & 07777, $dst_fh;
		409	chown $stat[4], $stat[5], $dst_fh;
		410	close $dst_fh;
		411	} else {
		412	$grp->result (-1);
		413	close $src_fh;
		414	close $dst_fh;
		415
		416	aioreq $pri;
		417	add $grp aio_unlink $dst;
		418	}
		419	};
		420	} else {
		421	$grp->result (-1);
		422	}
		423	},
		424
		425	} else {
		426	$grp->result (-1);
		427	}
		428	};
		429
		430	$grp
		431	}
		432
		433	=item aio_move $srcpath, $dstpath, $callback->($status)
		434
		435	Try to move the I<file> (directories not supported as either source or
		436	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		437	the C<0> (error) or C<-1> ok.
		438
		439	This is a composite request that tries to rename(2) the file first. If
		440	rename files with C<EXDEV>, it copies the file with C<aio_copy> and, if
		441	that is successful, unlinking the C<$srcpath>.
		442
		443	=cut
		444
		445	sub aio_move($$;$) {
		446	my ($src, $dst, $cb) = @_;
		447
		448	my $pri = aioreq_pri;
		449	my $grp = aio_group $cb;
		450
		451	aioreq_pri $pri;
		452	add $grp aio_rename $src, $dst, sub {
		453	if ($_[0] && $! == EXDEV) {
		454	aioreq_pri $pri;
		455	add $grp aio_copy $src, $dst, sub {
		456	$grp->result ($_[0]);
		457
		458	if (!$_[0]) {
		459	aioreq_pri $pri;
		460	add $grp aio_unlink $src;
		461	}
		462	};
		463	} else {
		464	$grp->result ($_[0]);
		465	}
		466	};
		467
		468	$grp
		469	}
		470
340	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	471	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
341		472
342	Scans a directory (similar to C<aio_readdir>) but additionally tries to	473	Scans a directory (similar to C<aio_readdir>) but additionally tries to
343	separate the entries of directory C<$path> into two sets of names, ones	474	efficiently separate the entries of directory C<$path> into two sets of
344	you can recurse into (directories or links to them), and ones you cannot	475	names, directories you can recurse into (directories), and ones you cannot
345	recurse into (everything else).	476	recurse into (everything else, including symlinks to directories).
346		477
347	C<aio_scandir> is a composite request that consists of many sub	478	C<aio_scandir> is a composite request that creates of many sub requests_
348	requests. C<$maxreq> specifies the maximum number of outstanding aio	479	C<$maxreq> specifies the maximum number of outstanding aio requests that
349	requests that this function generates. If it is C<< <= 0 >>, then a	480	this function generates. If it is C<< <= 0 >>, then a suitable default
350	suitable default will be chosen (currently 8).	481	will be chosen (currently 4).
351		482
352	On error, the callback is called without arguments, otherwise it receives	483	On error, the callback is called without arguments, otherwise it receives
353	two array-refs with path-relative entry names.	484	two array-refs with path-relative entry names.
354		485
355	Example:	486	Example:
…		…
392	=cut	523	=cut
393		524
394	sub aio_scandir($$$) {	525	sub aio_scandir($$$) {
395	my ($path, $maxreq, $cb) = @_;	526	my ($path, $maxreq, $cb) = @_;
396		527
		528	my $pri = aioreq_pri;
		529
		530	my $grp = aio_group $cb;
		531
397	$maxreq = 8 if $maxreq <= 0;	532	$maxreq = 4 if $maxreq <= 0;
398		533
399	# stat once	534	# stat once
		535	aioreq_pri $pri;
400	aio_stat $path, sub {	536	add $grp aio_stat $path, sub {
401	return $cb->() if $_[0];	537	return $grp->result () if $_[0];
402	my $now = time;	538	my $now = time;
403	my $hash1 = join ":", (stat _)[0,1,3,7,9];	539	my $hash1 = join ":", (stat _)[0,1,3,7,9];
404		540
405	# read the directory entries	541	# read the directory entries
		542	aioreq_pri $pri;
406	aio_readdir $path, sub {	543	add $grp aio_readdir $path, sub {
407	my $entries = shift	544	my $entries = shift
408	or return $cb->();	545	or return $grp->result ();
409		546
410	# stat the dir another time	547	# stat the dir another time
		548	aioreq_pri $pri;
411	aio_stat $path, sub {	549	add $grp aio_stat $path, sub {
412	my $hash2 = join ":", (stat _)[0,1,3,7,9];	550	my $hash2 = join ":", (stat _)[0,1,3,7,9];
413		551
414	my $ndirs;	552	my $ndirs;
415		553
416	# take the slow route if anything looks fishy	554	# take the slow route if anything looks fishy
…		…
418	$ndirs = -1;	556	$ndirs = -1;
419	} else {	557	} else {
420	# if nlink == 2, we are finished	558	# if nlink == 2, we are finished
421	# on non-posix-fs's, we rely on nlink < 2	559	# on non-posix-fs's, we rely on nlink < 2
422	$ndirs = (stat _)[3] - 2	560	$ndirs = (stat _)[3] - 2
423	or return $cb->([], $entries);	561	or return $grp->result ([], $entries);
424	}	562	}
425		563
426	# sort into likely dirs and likely nondirs	564	# sort into likely dirs and likely nondirs
427	# dirs == files without ".", short entries first	565	# dirs == files without ".", short entries first
428	$entries = [map $_->[0],	566	$entries = [map $_->[0],
…		…
430	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],	568	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
431	@$entries];	569	@$entries];
432		570
433	my (@dirs, @nondirs);	571	my (@dirs, @nondirs);
434		572
435	my ($statcb, $schedcb);	573	my $statgrp = add $grp aio_group sub {
436	my $nreq = 0;	574	$grp->result (\@dirs, \@nondirs);
		575	};
437		576
438	$schedcb = sub {	577	limit $statgrp $maxreq;
439	if (@$entries) {	578	feed $statgrp sub {
440	if ($nreq < $maxreq) {	579	return unless @$entries;
441	my $ent = pop @$entries;	580	my $entry = pop @$entries;
		581
		582	aioreq_pri $pri;
		583	add $statgrp aio_stat "$path/$entry/.", sub {
		584	if ($_[0] < 0) {
		585	push @nondirs, $entry;
		586	} else {
		587	# need to check for real directory
		588	aioreq_pri $pri;
		589	add $statgrp aio_lstat "$path/$entry", sub {
		590	if (-d _) {
		591	push @dirs, $entry;
		592
		593	unless (--$ndirs) {
		594	push @nondirs, @$entries;
		595	feed $statgrp;
		596	}
		597	} else {
		598	push @nondirs, $entry;
		599	}
442	$nreq++;	600	}
443	aio_stat "$path/$ent/.", sub { $statcb->($_[0], $ent) };
444	}	601	}
445	} elsif (!$nreq) {
446	# finished
447	undef $statcb;
448	undef $schedcb;
449	$cb->(\@dirs, \@nondirs) if $cb;
450	undef $cb;
451	}	602	};
452	};	603	};
453	$statcb = sub {
454	my ($status, $entry) = @_;
455
456	if ($status < 0) {
457	$nreq--;
458	push @nondirs, $entry;
459	&$schedcb;
460	} else {
461	# need to check for real directory
462	aio_lstat "$path/$entry", sub {
463	$nreq--;
464
465	if (-d _) {
466	push @dirs, $entry;
467
468	if (!--$ndirs) {
469	push @nondirs, @$entries;
470	$entries = [];
471	}
472	} else {
473	push @nondirs, $entry;
474	}
475
476	&$schedcb;
477	}
478	}
479	};
480
481	&$schedcb while @$entries && $nreq < $maxreq;
482	};	604	};
483	};	605	};
484	};	606	};
		607
		608	$grp
485	}	609	}
486		610
487	=item aio_fsync $fh, $callback->($status)	611	=item aio_fsync $fh, $callback->($status)
488		612
489	Asynchronously call fsync on the given filehandle and call the callback	613	Asynchronously call fsync on the given filehandle and call the callback
…		…
495	callback with the fdatasync result code.	619	callback with the fdatasync result code.
496		620
497	If this call isn't available because your OS lacks it or it couldn't be	621	If this call isn't available because your OS lacks it or it couldn't be
498	detected, it will be emulated by calling C<fsync> instead.	622	detected, it will be emulated by calling C<fsync> instead.
499		623
500	=item aio_group $callback->()	624	=item aio_group $callback->(...)
501		625
		626	This is a very special aio request: Instead of doing something, it is a
		627	container for other aio requests, which is useful if you want to bundle
		628	many requests into a single, composite, request with a definite callback
		629	and the ability to cancel the whole request with its subrequests.
		630
		631	Returns an object of class L<IO::AIO::GRP>. See its documentation below
		632	for more info.
		633
		634	Example:
		635
		636	my $grp = aio_group sub {
		637	print "all stats done\n";
		638	};
		639
		640	add $grp
		641	(aio_stat ...),
		642	(aio_stat ...),
		643	...;
		644
		645	=item aio_nop $callback->()
		646
		647	This is a special request - it does nothing in itself and is only used for
		648	side effects, such as when you want to add a dummy request to a group so
		649	that finishing the requests in the group depends on executing the given
		650	code.
		651
		652	While this request does nothing, it still goes through the execution
		653	phase and still requires a worker thread. Thus, the callback will not
		654	be executed immediately but only after other requests in the queue have
		655	entered their execution phase. This can be used to measure request
		656	latency.
		657
502	=item aio_sleep $fractional_seconds, $callback->() NOT EXPORTED	658	=item IO::AIO::aio_busy $fractional_seconds, $callback->() NOT EXPORTED
503		659
504	Mainly used for debugging and benchmarking, this aio request puts one of	660	Mainly used for debugging and benchmarking, this aio request puts one of
505	the request workers to sleep for the given time.	661	the request workers to sleep for the given time.
506		662
		663	While it is theoretically handy to have simple I/O scheduling requests
		664	like sleep and file handle readable/writable, the overhead this creates is
		665	immense (it blocks a thread for a long time) so do not use this function
		666	except to put your application under artificial I/O pressure.
		667
507	=back	668	=back
508		669
509	=head2 IO::AIO::REQ CLASS	670	=head2 IO::AIO::REQ CLASS
510		671
511	All non-aggregate C<aio_*> functions return an object of this class when	672	All non-aggregate C<aio_*> functions return an object of this class when
512	called in non-void context.	673	called in non-void context.
513		674
514	A request always moves through the following five states in its lifetime,
515	in order: B<ready> (request has been created, but has not been executed
516	yet), B<execute> (request is currently being executed), B<pending>
517	(request has been executed but callback has not been called yet),
518	B<result> (results are being processed synchronously, includes calling the
519	callback) and B<done> (request has reached the end of its lifetime and
520	holds no resources anymore).
521
522	=over 4	675	=over 4
523		676
524	=item $req->cancel	677	=item cancel $req
525		678
526	Cancels the request, if possible. Has the effect of skipping execution	679	Cancels the request, if possible. Has the effect of skipping execution
527	when entering the B<execute> state and skipping calling the callback when	680	when entering the B<execute> state and skipping calling the callback when
528	entering the the B<result> state, but will leave the request otherwise	681	entering the the B<result> state, but will leave the request otherwise
529	untouched. That means that requests that currently execute will not be	682	untouched. That means that requests that currently execute will not be
530	stopped and resources held by the request will not be freed prematurely.	683	stopped and resources held by the request will not be freed prematurely.
531		684
		685	=item cb $req $callback->(...)
		686
		687	Replace (or simply set) the callback registered to the request.
		688
		689	=back
		690
		691	=head2 IO::AIO::GRP CLASS
		692
		693	This class is a subclass of L<IO::AIO::REQ>, so all its methods apply to
		694	objects of this class, too.
		695
		696	A IO::AIO::GRP object is a special request that can contain multiple other
		697	aio requests.
		698
		699	You create one by calling the C<aio_group> constructing function with a
		700	callback that will be called when all contained requests have entered the
		701	C<done> state:
		702
		703	my $grp = aio_group sub {
		704	print "all requests are done\n";
		705	};
		706
		707	You add requests by calling the C<add> method with one or more
		708	C<IO::AIO::REQ> objects:
		709
		710	$grp->add (aio_unlink "...");
		711
		712	add $grp aio_stat "...", sub {
		713	$_[0] or return $grp->result ("error");
		714
		715	# add another request dynamically, if first succeeded
		716	add $grp aio_open "...", sub {
		717	$grp->result ("ok");
		718	};
		719	};
		720
		721	This makes it very easy to create composite requests (see the source of
		722	C<aio_move> for an application) that work and feel like simple requests.
		723
		724	=over 4
		725
		726	=item * The IO::AIO::GRP objects will be cleaned up during calls to
		727	C<IO::AIO::poll_cb>, just like any other request.
		728
		729	=item * They can be canceled like any other request. Canceling will cancel not
		730	only the request itself, but also all requests it contains.
		731
		732	=item * They can also can also be added to other IO::AIO::GRP objects.
		733
		734	=item * You must not add requests to a group from within the group callback (or
		735	any later time).
		736
		737	=back
		738
		739	Their lifetime, simplified, looks like this: when they are empty, they
		740	will finish very quickly. If they contain only requests that are in the
		741	C<done> state, they will also finish. Otherwise they will continue to
		742	exist.
		743
		744	That means after creating a group you have some time to add requests. And
		745	in the callbacks of those requests, you can add further requests to the
		746	group. And only when all those requests have finished will the the group
		747	itself finish.
		748
		749	=over 4
		750
		751	=item add $grp ...
		752
		753	=item $grp->add (...)
		754
		755	Add one or more requests to the group. Any type of L<IO::AIO::REQ> can
		756	be added, including other groups, as long as you do not create circular
		757	dependencies.
		758
		759	Returns all its arguments.
		760
		761	=item $grp->cancel_subs
		762
		763	Cancel all subrequests and clears any feeder, but not the group request
		764	itself. Useful when you queued a lot of events but got a result early.
		765
		766	=item $grp->result (...)
		767
		768	Set the result value(s) that will be passed to the group callback when all
		769	subrequests have finished and set thre groups errno to the current value
		770	of errno (just like calling C<errno> without an error number). By default,
		771	no argument will be passed and errno is zero.
		772
		773	=item $grp->errno ([$errno])
		774
		775	Sets the group errno value to C<$errno>, or the current value of errno
		776	when the argument is missing.
		777
		778	Every aio request has an associated errno value that is restored when
		779	the callback is invoked. This method lets you change this value from its
		780	default (0).
		781
		782	Calling C<result> will also set errno, so make sure you either set C<$!>
		783	before the call to C<result>, or call c<errno> after it.
		784
		785	=item feed $grp $callback->($grp)
		786
		787	Sets a feeder/generator on this group: every group can have an attached
		788	generator that generates requests if idle. The idea behind this is that,
		789	although you could just queue as many requests as you want in a group,
		790	this might starve other requests for a potentially long time. For
		791	example, C<aio_scandir> might generate hundreds of thousands C<aio_stat>
		792	requests, delaying any later requests for a long time.
		793
		794	To avoid this, and allow incremental generation of requests, you can
		795	instead a group and set a feeder on it that generates those requests. The
		796	feed callback will be called whenever there are few enough (see C<limit>,
		797	below) requests active in the group itself and is expected to queue more
		798	requests.
		799
		800	The feed callback can queue as many requests as it likes (i.e. C<add> does
		801	not impose any limits).
		802
		803	If the feed does not queue more requests when called, it will be
		804	automatically removed from the group.
		805
		806	If the feed limit is C<0>, it will be set to C<2> automatically.
		807
		808	Example:
		809
		810	# stat all files in @files, but only ever use four aio requests concurrently:
		811
		812	my $grp = aio_group sub { print "finished\n" };
		813	limit $grp 4;
		814	feed $grp sub {
		815	my $file = pop @files
		816	or return;
		817
		818	add $grp aio_stat $file, sub { ... };
		819	};
		820
		821	=item limit $grp $num
		822
		823	Sets the feeder limit for the group: The feeder will be called whenever
		824	the group contains less than this many requests.
		825
		826	Setting the limit to C<0> will pause the feeding process.
		827
532	=back	828	=back
533		829
534	=head2 SUPPORT FUNCTIONS	830	=head2 SUPPORT FUNCTIONS
535		831
536	=over 4	832	=over 4
…		…
548		844
549	Process all outstanding events on the result pipe. You have to call this	845	Process all outstanding events on the result pipe. You have to call this
550	regularly. Returns the number of events processed. Returns immediately	846	regularly. Returns the number of events processed. Returns immediately
551	when no events are outstanding.	847	when no events are outstanding.
552		848
		849	If not all requests were processed for whatever reason, the filehandle
		850	will still be ready when C<poll_cb> returns.
		851
553	Example: Install an Event watcher that automatically calls	852	Example: Install an Event watcher that automatically calls
554	IO::AIO::poll_cb with high priority:	853	IO::AIO::poll_cb with high priority:
555		854
556	Event->io (fd => IO::AIO::poll_fileno,	855	Event->io (fd => IO::AIO::poll_fileno,
557	poll => 'r', async => 1,	856	poll => 'r', async => 1,
558	cb => \&IO::AIO::poll_cb);	857	cb => \&IO::AIO::poll_cb);
559		858
		859	=item IO::AIO::poll_some $max_requests
		860
		861	Similar to C<poll_cb>, but only processes up to C<$max_requests> requests
		862	at a time.
		863
		864	Useful if you want to ensure some level of interactiveness when perl is
		865	not fast enough to process all requests in time.
		866
		867	Example: Install an Event watcher that automatically calls
		868	IO::AIO::poll_some with low priority, to ensure that other parts of the
		869	program get the CPU sometimes even under high AIO load.
		870
		871	Event->io (fd => IO::AIO::poll_fileno,
		872	poll => 'r', nice => 1,
		873	cb => sub { IO::AIO::poll_some 256 });
		874
560	=item IO::AIO::poll_wait	875	=item IO::AIO::poll_wait
561		876
562	Wait till the result filehandle becomes ready for reading (simply does a	877	Wait till the result filehandle becomes ready for reading (simply does a
563	C<select> on the filehandle. This is useful if you want to synchronously wait	878	C<select> on the filehandle. This is useful if you want to synchronously wait
564	for some requests to finish).	879	for some requests to finish).
565		880
566	See C<nreqs> for an example.	881	See C<nreqs> for an example.
567		882
568	=item IO::AIO::nreqs	883	=item IO::AIO::nreqs
569		884
570	Returns the number of requests currently outstanding (i.e. for which their	885	Returns the number of requests currently in the ready, execute or pending
571	callback has not been invoked yet).	886	states (i.e. for which their callback has not been invoked yet).
572		887
573	Example: wait till there are no outstanding requests anymore:	888	Example: wait till there are no outstanding requests anymore:
574		889
575	IO::AIO::poll_wait, IO::AIO::poll_cb	890	IO::AIO::poll_wait, IO::AIO::poll_cb
576	while IO::AIO::nreqs;	891	while IO::AIO::nreqs;
577		892
		893	=item IO::AIO::nready
		894
		895	Returns the number of requests currently in the ready state (not yet
		896	executed).
		897
		898	=item IO::AIO::npending
		899
		900	Returns the number of requests currently in the pending state (executed,
		901	but not yet processed by poll_cb).
		902
578	=item IO::AIO::flush	903	=item IO::AIO::flush
579		904
580	Wait till all outstanding AIO requests have been handled.	905	Wait till all outstanding AIO requests have been handled.
581		906
582	Strictly equivalent to:	907	Strictly equivalent to:
…		…
593	IO::AIO::poll_wait, IO::AIO::poll_cb	918	IO::AIO::poll_wait, IO::AIO::poll_cb
594	if IO::AIO::nreqs;	919	if IO::AIO::nreqs;
595		920
596	=item IO::AIO::min_parallel $nthreads	921	=item IO::AIO::min_parallel $nthreads
597		922
598	Set the minimum number of AIO threads to C<$nthreads>. The current default	923	Set the minimum number of AIO threads to C<$nthreads>. The current
599	is C<4>, which means four asynchronous operations can be done at one time	924	default is C<8>, which means eight asynchronous operations can execute
600	(the number of outstanding operations, however, is unlimited).	925	concurrently at any one time (the number of outstanding requests,
		926	however, is unlimited).
601		927
602	IO::AIO starts threads only on demand, when an AIO request is queued and	928	IO::AIO starts threads only on demand, when an AIO request is queued and
603	no free thread exists.	929	no free thread exists.
604		930
605	It is recommended to keep the number of threads low, as some Linux	931	It is recommended to keep the number of threads relatively low, as some
606	kernel versions will scale negatively with the number of threads (higher	932	Linux kernel versions will scale negatively with the number of threads
607	parallelity => MUCH higher latency). With current Linux 2.6 versions, 4-32	933	(higher parallelity => MUCH higher latency). With current Linux 2.6
608	threads should be fine.	934	versions, 4-32 threads should be fine.
609		935
610	Under most circumstances you don't need to call this function, as the	936	Under most circumstances you don't need to call this function, as the
611	module selects a default that is suitable for low to moderate load.	937	module selects a default that is suitable for low to moderate load.
612		938
613	=item IO::AIO::max_parallel $nthreads	939	=item IO::AIO::max_parallel $nthreads
…		…
622	This module automatically runs C<max_parallel 0> at program end, to ensure	948	This module automatically runs C<max_parallel 0> at program end, to ensure
623	that all threads are killed and that there are no outstanding requests.	949	that all threads are killed and that there are no outstanding requests.
624		950
625	Under normal circumstances you don't need to call this function.	951	Under normal circumstances you don't need to call this function.
626		952
627	=item $oldnreqs = IO::AIO::max_outstanding $nreqs	953	=item $oldmaxreqs = IO::AIO::max_outstanding $maxreqs
		954
		955	This is a very bad function to use in interactive programs because it
		956	blocks, and a bad way to reduce concurrency because it is inexact: Better
		957	use an C<aio_group> together with a feed callback.
628		958
629	Sets the maximum number of outstanding requests to C<$nreqs>. If you	959	Sets the maximum number of outstanding requests to C<$nreqs>. If you
630	try to queue up more than this number of requests, the caller will block until	960	to queue up more than this number of requests, the next call to the
631	some requests have been handled.	961	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
		962	function will block until the limit is no longer exceeded.
632		963
633	The default is very large, so normally there is no practical limit. If you	964	The default value is very large, so there is no practical limit on the
634	queue up many requests in a loop it often improves speed if you set	965	number of outstanding requests.
635	this to a relatively low number, such as C<100>.
636		966
637	Under normal circumstances you don't need to call this function.	967	You can still queue as many requests as you want. Therefore,
		968	C<max_oustsanding> is mainly useful in simple scripts (with low values) or
		969	as a stop gap to shield against fatal memory overflow (with large values).
638		970
639	=back	971	=back
640		972
641	=cut	973	=cut
642		974
…		…
654	or return undef;	986	or return undef;
655		987
656	*$sym	988	*$sym
657	}	989	}
658		990
659	min_parallel 4;	991	min_parallel 8;
660		992
661	END {	993	END {
662	max_parallel 0;	994	flush;
663	}	995	};
664		996
665	1;	997	1;
666		998
667	=head2 FORK BEHAVIOUR	999	=head2 FORK BEHAVIOUR
668		1000
669	This module should do "the right thing" when the process using it forks:	1001	This module should do "the right thing" when the process using it forks:
670		1002
671	Before the fork, IO::AIO enters a quiescent state where no requests	1003	Before the fork, IO::AIO enters a quiescent state where no requests
672	can be added in other threads and no results will be processed. After	1004	can be added in other threads and no results will be processed. After
673	the fork the parent simply leaves the quiescent state and continues	1005	the fork the parent simply leaves the quiescent state and continues
674	request/result processing, while the child clears the request/result	1006	request/result processing, while the child frees the request/result queue
675	queue (so the requests started before the fork will only be handled in	1007	(so that the requests started before the fork will only be handled in the
676	the parent). Threads will be started on demand until the limit ste in the	1008	parent). Threads will be started on demand until the limit set in the
677	parent process has been reached again.	1009	parent process has been reached again.
678		1010
679	In short: the parent will, after a short pause, continue as if fork had	1011	In short: the parent will, after a short pause, continue as if fork had
680	not been called, while the child will act as if IO::AIO has not been used	1012	not been called, while the child will act as if IO::AIO has not been used
681	yet.	1013	yet.
682		1014
		1015	=head2 MEMORY USAGE
		1016
		1017	Per-request usage:
		1018
		1019	Each aio request uses - depending on your architecture - around 100-200
		1020	bytes of memory. In addition, stat requests need a stat buffer (possibly
		1021	a few hundred bytes), readdir requires a result buffer and so on. Perl
		1022	scalars and other data passed into aio requests will also be locked and
		1023	will consume memory till the request has entered the done state.
		1024
		1025	This is now awfully much, so queuing lots of requests is not usually a
		1026	problem.
		1027
		1028	Per-thread usage:
		1029
		1030	In the execution phase, some aio requests require more memory for
		1031	temporary buffers, and each thread requires a stack and other data
		1032	structures (usually around 16k-128k, depending on the OS).
		1033
		1034	=head1 KNOWN BUGS
		1035
		1036	Known bugs will be fixed in the next release.
		1037
683	=head1 SEE ALSO	1038	=head1 SEE ALSO
684		1039
685	L<Coro>, L<Linux::AIO> (obsolete).	1040	L<Coro::AIO>.
686		1041
687	=head1 AUTHOR	1042	=head1 AUTHOR
688		1043
689	Marc Lehmann <schmorp@schmorp.de>	1044	Marc Lehmann <schmorp@schmorp.de>
690	http://home.schmorp.de/	1045	http://home.schmorp.de/

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Comparing IO-AIO/AIO.pm (file contents): Revision 1.54 by root, Sun Oct 22 00:19:05 2006 UTC vs. Revision 1.82 by root, Fri Oct 27 20:10:06 2006 UTC

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Comparing IO-AIO/AIO.pm (file contents):
Revision 1.54 by root, Sun Oct 22 00:19:05 2006 UTC vs.
Revision 1.82 by root, Fri Oct 27 20:10:06 2006 UTC