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

Comparing IO-AIO/AIO.pm (file contents):
Revision 1.55 by root, Sun Oct 22 00:49:29 2006 UTC vs.
Revision 1.81 by root, Fri Oct 27 19:17:23 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
…		…
73	use base 'Exporter';	128	use base 'Exporter';
74		129
75	BEGIN {	130	BEGIN {
76	our $VERSION = '2.0';	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_group aio_nop);
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);
…		…
117	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
118	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)
119	use something else.	176	use something else.
120		177
121	=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.
122		210
123	=item aio_open $pathname, $flags, $mode, $callback->($fh)	211	=item aio_open $pathname, $flags, $mode, $callback->($fh)
124		212
125	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
126	created filehandle for the file.	214	created filehandle for the file.
…		…
198	=cut	286	=cut
199		287
200	sub aio_move($$$) {	288	sub aio_move($$$) {
201	my ($src, $dst, $cb) = @_;	289	my ($src, $dst, $cb) = @_;
202		290
		291	my $pri = aioreq_pri;
203	my $grp = aio_group;	292	my $grp = aio_group $cb;
204		293
		294	aioreq_pri $pri;
205	add $grp aio_rename $src, $dst, sub {	295	add $grp aio_rename $src, $dst, sub {
206	if ($_[0] && $! == EXDEV) {	296	if ($_[0] && $! == EXDEV) {
		297	aioreq_pri $pri;
207	add $grp aio_open $src, O_RDONLY, 0, sub {	298	add $grp aio_open $src, O_RDONLY, 0, sub {
208	if (my $src_fh = $_[0]) {	299	if (my $src_fh = $_[0]) {
209	my @stat = stat $src_fh;	300	my @stat = stat $src_fh;
210		301
		302	aioreq_pri $pri;
211	add $grp aio_open $dst, O_WRONLY, 0200, sub {	303	add $grp aio_open $dst, O_WRONLY, 0200, sub {
212	if (my $dst_fh = $_[0]) {	304	if (my $dst_fh = $_[0]) {
		305	aioreq_pri $pri;
213	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {	306	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
214	close $src_fh;	307	close $src_fh;
215		308
216	if ($_[0] == $stat[7]) {	309	if ($_[0] == $stat[7]) {
217	utime $stat[8], $stat[9], $dst;	310	utime $stat[8], $stat[9], $dst;
218	chmod $stat[2] & 07777, $dst_fh;	311	chmod $stat[2] & 07777, $dst_fh;
219	chown $stat[4], $stat[5], $dst_fh;	312	chown $stat[4], $stat[5], $dst_fh;
220	close $dst_fh;	313	close $dst_fh;
221		314
		315	aioreq_pri $pri;
222	add $grp aio_unlink $src, sub {	316	add $grp aio_unlink $src, sub {
223	$cb->($_[0]);	317	$grp->result ($_[0]);
224	};	318	};
225	} else {	319	} else {
226	my $errno = $!;	320	my $errno = $!;
		321	aioreq_pri $pri;
227	add $grp aio_unlink $dst, sub {	322	add $grp aio_unlink $dst, sub {
228	$! = $errno;	323	$! = $errno;
229	$cb->(-1);	324	$grp->result (-1);
230	};	325	};
231	}	326	}
232	};	327	};
233	} else {	328	} else {
234	$cb->(-1);	329	$grp->result (-1);
235	}	330	}
236	},	331	},
237		332
238	} else {	333	} else {
239	$cb->(-1);	334	$grp->result (-1);
240	}	335	}
241	};	336	};
242	} else {	337	} else {
243	$cb->($_[0]);	338	$grp->result ($_[0]);
244	}	339	}
245	};	340	};
246		341
247	$grp	342	$grp
248	}	343	}
…		…
341	with the filenames.	436	with the filenames.
342		437
343	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	438	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
344		439
345	Scans a directory (similar to C<aio_readdir>) but additionally tries to	440	Scans a directory (similar to C<aio_readdir>) but additionally tries to
346	separate the entries of directory C<$path> into two sets of names, ones	441	efficiently separate the entries of directory C<$path> into two sets of
347	you can recurse into (directories or links to them), and ones you cannot	442	names, directories you can recurse into (directories), and ones you cannot
348	recurse into (everything else).	443	recurse into (everything else, including symlinks to directories).
349		444
350	C<aio_scandir> is a composite request that consists of many sub	445	C<aio_scandir> is a composite request that creates of many sub requests_
351	requests. C<$maxreq> specifies the maximum number of outstanding aio	446	C<$maxreq> specifies the maximum number of outstanding aio requests that
352	requests that this function generates. If it is C<< <= 0 >>, then a	447	this function generates. If it is C<< <= 0 >>, then a suitable default
353	suitable default will be chosen (currently 8).	448	will be chosen (currently 4).
354		449
355	On error, the callback is called without arguments, otherwise it receives	450	On error, the callback is called without arguments, otherwise it receives
356	two array-refs with path-relative entry names.	451	two array-refs with path-relative entry names.
357		452
358	Example:	453	Example:
…		…
395	=cut	490	=cut
396		491
397	sub aio_scandir($$$) {	492	sub aio_scandir($$$) {
398	my ($path, $maxreq, $cb) = @_;	493	my ($path, $maxreq, $cb) = @_;
399		494
		495	my $pri = aioreq_pri;
		496
400	my $grp = aio_group;	497	my $grp = aio_group $cb;
401		498
402	$maxreq = 8 if $maxreq <= 0;	499	$maxreq = 4 if $maxreq <= 0;
403		500
404	# stat once	501	# stat once
		502	aioreq_pri $pri;
405	add $grp aio_stat $path, sub {	503	add $grp aio_stat $path, sub {
406	return $cb->() if $_[0];	504	return $grp->result () if $_[0];
407	my $now = time;	505	my $now = time;
408	my $hash1 = join ":", (stat _)[0,1,3,7,9];	506	my $hash1 = join ":", (stat _)[0,1,3,7,9];
409		507
410	# read the directory entries	508	# read the directory entries
		509	aioreq_pri $pri;
411	add $grp aio_readdir $path, sub {	510	add $grp aio_readdir $path, sub {
412	my $entries = shift	511	my $entries = shift
413	or return $cb->();	512	or return $grp->result ();
414		513
415	# stat the dir another time	514	# stat the dir another time
		515	aioreq_pri $pri;
416	add $grp aio_stat $path, sub {	516	add $grp aio_stat $path, sub {
417	my $hash2 = join ":", (stat _)[0,1,3,7,9];	517	my $hash2 = join ":", (stat _)[0,1,3,7,9];
418		518
419	my $ndirs;	519	my $ndirs;
420		520
…		…
423	$ndirs = -1;	523	$ndirs = -1;
424	} else {	524	} else {
425	# if nlink == 2, we are finished	525	# if nlink == 2, we are finished
426	# on non-posix-fs's, we rely on nlink < 2	526	# on non-posix-fs's, we rely on nlink < 2
427	$ndirs = (stat _)[3] - 2	527	$ndirs = (stat _)[3] - 2
428	or return $cb->([], $entries);	528	or return $grp->result ([], $entries);
429	}	529	}
430		530
431	# sort into likely dirs and likely nondirs	531	# sort into likely dirs and likely nondirs
432	# dirs == files without ".", short entries first	532	# dirs == files without ".", short entries first
433	$entries = [map $_->[0],	533	$entries = [map $_->[0],
…		…
435	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],	535	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
436	@$entries];	536	@$entries];
437		537
438	my (@dirs, @nondirs);	538	my (@dirs, @nondirs);
439		539
440	my ($statcb, $schedcb);	540	my $statgrp = add $grp aio_group sub {
441	my $nreq = 0;	541	$grp->result (\@dirs, \@nondirs);
		542	};
442		543
443	$schedcb = sub {	544	limit $statgrp $maxreq;
444	if (@$entries) {	545	feed $statgrp sub {
445	if ($nreq < $maxreq) {	546	return unless @$entries;
446	my $ent = pop @$entries;	547	my $entry = pop @$entries;
		548
		549	aioreq_pri $pri;
		550	add $statgrp aio_stat "$path/$entry/.", sub {
		551	if ($_[0] < 0) {
		552	push @nondirs, $entry;
		553	} else {
		554	# need to check for real directory
		555	aioreq_pri $pri;
		556	add $statgrp aio_lstat "$path/$entry", sub {
		557	if (-d _) {
		558	push @dirs, $entry;
		559
		560	unless (--$ndirs) {
		561	push @nondirs, @$entries;
		562	feed $statgrp;
		563	}
		564	} else {
		565	push @nondirs, $entry;
		566	}
447	$nreq++;	567	}
448	add $grp aio_stat "$path/$ent/.", sub { $statcb->($_[0], $ent) };
449	}	568	}
450	} elsif (!$nreq) {
451	# finished
452	undef $statcb;
453	undef $schedcb;
454	$cb->(\@dirs, \@nondirs) if $cb;
455	undef $cb;
456	}	569	};
457	};	570	};
458	$statcb = sub {
459	my ($status, $entry) = @_;
460
461	if ($status < 0) {
462	$nreq--;
463	push @nondirs, $entry;
464	&$schedcb;
465	} else {
466	# need to check for real directory
467	add $grp aio_lstat "$path/$entry", sub {
468	$nreq--;
469
470	if (-d _) {
471	push @dirs, $entry;
472
473	if (!--$ndirs) {
474	push @nondirs, @$entries;
475	$entries = [];
476	}
477	} else {
478	push @nondirs, $entry;
479	}
480
481	&$schedcb;
482	}
483	}
484	};
485
486	&$schedcb while @$entries && $nreq < $maxreq;
487	};	571	};
488	};	572	};
489	};	573	};
490		574
491	$grp	575	$grp
…		…
502	callback with the fdatasync result code.	586	callback with the fdatasync result code.
503		587
504	If this call isn't available because your OS lacks it or it couldn't be	588	If this call isn't available because your OS lacks it or it couldn't be
505	detected, it will be emulated by calling C<fsync> instead.	589	detected, it will be emulated by calling C<fsync> instead.
506		590
507	=item aio_group $callback->()	591	=item aio_group $callback->(...)
508
509	[EXPERIMENTAL]
510		592
511	This is a very special aio request: Instead of doing something, it is a	593	This is a very special aio request: Instead of doing something, it is a
512	container for other aio requests, which is useful if you want to bundle	594	container for other aio requests, which is useful if you want to bundle
513	many requests into a single, composite, request.	595	many requests into a single, composite, request with a definite callback
		596	and the ability to cancel the whole request with its subrequests.
514		597
515	Returns an object of class L<IO::AIO::GRP>. See its documentation below	598	Returns an object of class L<IO::AIO::GRP>. See its documentation below
516	for more info.	599	for more info.
517		600
518	Example:	601	Example:
…		…
524	add $grp	607	add $grp
525	(aio_stat ...),	608	(aio_stat ...),
526	(aio_stat ...),	609	(aio_stat ...),
527	...;	610	...;
528		611
		612	=item aio_nop $callback->()
		613
		614	This is a special request - it does nothing in itself and is only used for
		615	side effects, such as when you want to add a dummy request to a group so
		616	that finishing the requests in the group depends on executing the given
		617	code.
		618
		619	While this request does nothing, it still goes through the execution
		620	phase and still requires a worker thread. Thus, the callback will not
		621	be executed immediately but only after other requests in the queue have
		622	entered their execution phase. This can be used to measure request
		623	latency.
		624
529	=item aio_sleep $fractional_seconds, $callback->() NOT EXPORTED	625	=item IO::AIO::aio_busy $fractional_seconds, $callback->() NOT EXPORTED
530		626
531	Mainly used for debugging and benchmarking, this aio request puts one of	627	Mainly used for debugging and benchmarking, this aio request puts one of
532	the request workers to sleep for the given time.	628	the request workers to sleep for the given time.
533		629
		630	While it is theoretically handy to have simple I/O scheduling requests
		631	like sleep and file handle readable/writable, the overhead this creates is
		632	immense (it blocks a thread for a long time) so do not use this function
		633	except to put your application under artificial I/O pressure.
		634
534	=back	635	=back
535		636
536	=head2 IO::AIO::REQ CLASS	637	=head2 IO::AIO::REQ CLASS
537		638
538	All non-aggregate C<aio_*> functions return an object of this class when	639	All non-aggregate C<aio_*> functions return an object of this class when
539	called in non-void context.	640	called in non-void context.
540		641
541	A request always moves through the following five states in its lifetime,
542	in order: B<ready> (request has been created, but has not been executed
543	yet), B<execute> (request is currently being executed), B<pending>
544	(request has been executed but callback has not been called yet),
545	B<result> (results are being processed synchronously, includes calling the
546	callback) and B<done> (request has reached the end of its lifetime and
547	holds no resources anymore).
548
549	=over 4	642	=over 4
550		643
551	=item $req->cancel	644	=item cancel $req
552		645
553	Cancels the request, if possible. Has the effect of skipping execution	646	Cancels the request, if possible. Has the effect of skipping execution
554	when entering the B<execute> state and skipping calling the callback when	647	when entering the B<execute> state and skipping calling the callback when
555	entering the the B<result> state, but will leave the request otherwise	648	entering the the B<result> state, but will leave the request otherwise
556	untouched. That means that requests that currently execute will not be	649	untouched. That means that requests that currently execute will not be
557	stopped and resources held by the request will not be freed prematurely.	650	stopped and resources held by the request will not be freed prematurely.
558		651
		652	=item cb $req $callback->(...)
		653
		654	Replace (or simply set) the callback registered to the request.
		655
559	=back	656	=back
560		657
561	=head2 IO::AIO::GRP CLASS	658	=head2 IO::AIO::GRP CLASS
562		659
563	This class is a subclass of L<IO::AIO::REQ>, so all its methods apply to	660	This class is a subclass of L<IO::AIO::REQ>, so all its methods apply to
…		…
577	You add requests by calling the C<add> method with one or more	674	You add requests by calling the C<add> method with one or more
578	C<IO::AIO::REQ> objects:	675	C<IO::AIO::REQ> objects:
579		676
580	$grp->add (aio_unlink "...");	677	$grp->add (aio_unlink "...");
581		678
582	add $grp aio_stat "...", sub { ... };	679	add $grp aio_stat "...", sub {
		680	$_[0] or return $grp->result ("error");
		681
		682	# add another request dynamically, if first succeeded
		683	add $grp aio_open "...", sub {
		684	$grp->result ("ok");
		685	};
		686	};
583		687
584	This makes it very easy to create composite requests (see the source of	688	This makes it very easy to create composite requests (see the source of
585	C<aio_move> for an application) that work and feel like simple requests.	689	C<aio_move> for an application) that work and feel like simple requests.
586		690
		691	=over 4
		692
587	The IO::AIO::GRP objects will be cleaned up during calls to	693	=item * The IO::AIO::GRP objects will be cleaned up during calls to
588	C<IO::AIO::poll_cb>, just like any other request.	694	C<IO::AIO::poll_cb>, just like any other request.
589		695
590	They can be canceled like any other request. Canceling will cancel not	696	=item * They can be canceled like any other request. Canceling will cancel not
591	just the request itself, but also all requests it contains.	697	only the request itself, but also all requests it contains.
592		698
593	They can also can also be added to other IO::AIO::GRP objects.	699	=item * They can also can also be added to other IO::AIO::GRP objects.
		700
		701	=item * You must not add requests to a group from within the group callback (or
		702	any later time).
		703
		704	=back
594		705
595	Their lifetime, simplified, looks like this: when they are empty, they	706	Their lifetime, simplified, looks like this: when they are empty, they
596	will finish very quickly. If they contain only requests that are in the	707	will finish very quickly. If they contain only requests that are in the
597	C<done> state, they will also finish. Otherwise they will continue to	708	C<done> state, they will also finish. Otherwise they will continue to
598	exist.	709	exist.
599		710
		711	That means after creating a group you have some time to add requests. And
		712	in the callbacks of those requests, you can add further requests to the
		713	group. And only when all those requests have finished will the the group
		714	itself finish.
		715
600	=over 4	716	=over 4
601		717
		718	=item add $grp ...
		719
602	=item $grp->add (...)	720	=item $grp->add (...)
603		721
604	=item add $grp ...	722	Add one or more requests to the group. Any type of L<IO::AIO::REQ> can
		723	be added, including other groups, as long as you do not create circular
		724	dependencies.
605		725
606	Add one or more	726	Returns all its arguments.
607	Cancels the request, if possible. Has the effect of skipping execution	727
608	when entering the B<execute> state and skipping calling the callback when	728	=item $grp->cancel_subs
609	entering the the B<result> state, but will leave the request otherwise	729
610	untouched. That means that requests that currently execute will not be	730	Cancel all subrequests and clears any feeder, but not the group request
611	stopped and resources held by the request will not be freed prematurely.	731	itself. Useful when you queued a lot of events but got a result early.
		732
		733	=item $grp->result (...)
		734
		735	Set the result value(s) that will be passed to the group callback when all
		736	subrequests have finished and set thre groups errno to the current value
		737	of errno (just like calling C<errno> without an error number). By default,
		738	no argument will be passed and errno is zero.
		739
		740	=item $grp->errno ([$errno])
		741
		742	Sets the group errno value to C<$errno>, or the current value of errno
		743	when the argument is missing.
		744
		745	Every aio request has an associated errno value that is restored when
		746	the callback is invoked. This method lets you change this value from its
		747	default (0).
		748
		749	Calling C<result> will also set errno, so make sure you either set C<$!>
		750	before the call to C<result>, or call c<errno> after it.
		751
		752	=item feed $grp $callback->($grp)
		753
		754	Sets a feeder/generator on this group: every group can have an attached
		755	generator that generates requests if idle. The idea behind this is that,
		756	although you could just queue as many requests as you want in a group,
		757	this might starve other requests for a potentially long time. For
		758	example, C<aio_scandir> might generate hundreds of thousands C<aio_stat>
		759	requests, delaying any later requests for a long time.
		760
		761	To avoid this, and allow incremental generation of requests, you can
		762	instead a group and set a feeder on it that generates those requests. The
		763	feed callback will be called whenever there are few enough (see C<limit>,
		764	below) requests active in the group itself and is expected to queue more
		765	requests.
		766
		767	The feed callback can queue as many requests as it likes (i.e. C<add> does
		768	not impose any limits).
		769
		770	If the feed does not queue more requests when called, it will be
		771	automatically removed from the group.
		772
		773	If the feed limit is C<0>, it will be set to C<2> automatically.
		774
		775	Example:
		776
		777	# stat all files in @files, but only ever use four aio requests concurrently:
		778
		779	my $grp = aio_group sub { print "finished\n" };
		780	limit $grp 4;
		781	feed $grp sub {
		782	my $file = pop @files
		783	or return;
		784
		785	add $grp aio_stat $file, sub { ... };
		786	};
		787
		788	=item limit $grp $num
		789
		790	Sets the feeder limit for the group: The feeder will be called whenever
		791	the group contains less than this many requests.
		792
		793	Setting the limit to C<0> will pause the feeding process.
612		794
613	=back	795	=back
614		796
615	=head2 SUPPORT FUNCTIONS	797	=head2 SUPPORT FUNCTIONS
616		798
…		…
629		811
630	Process all outstanding events on the result pipe. You have to call this	812	Process all outstanding events on the result pipe. You have to call this
631	regularly. Returns the number of events processed. Returns immediately	813	regularly. Returns the number of events processed. Returns immediately
632	when no events are outstanding.	814	when no events are outstanding.
633		815
		816	If not all requests were processed for whatever reason, the filehandle
		817	will still be ready when C<poll_cb> returns.
		818
634	Example: Install an Event watcher that automatically calls	819	Example: Install an Event watcher that automatically calls
635	IO::AIO::poll_cb with high priority:	820	IO::AIO::poll_cb with high priority:
636		821
637	Event->io (fd => IO::AIO::poll_fileno,	822	Event->io (fd => IO::AIO::poll_fileno,
638	poll => 'r', async => 1,	823	poll => 'r', async => 1,
639	cb => \&IO::AIO::poll_cb);	824	cb => \&IO::AIO::poll_cb);
640		825
		826	=item IO::AIO::poll_some $max_requests
		827
		828	Similar to C<poll_cb>, but only processes up to C<$max_requests> requests
		829	at a time.
		830
		831	Useful if you want to ensure some level of interactiveness when perl is
		832	not fast enough to process all requests in time.
		833
		834	Example: Install an Event watcher that automatically calls
		835	IO::AIO::poll_some with low priority, to ensure that other parts of the
		836	program get the CPU sometimes even under high AIO load.
		837
		838	Event->io (fd => IO::AIO::poll_fileno,
		839	poll => 'r', nice => 1,
		840	cb => sub { IO::AIO::poll_some 256 });
		841
641	=item IO::AIO::poll_wait	842	=item IO::AIO::poll_wait
642		843
643	Wait till the result filehandle becomes ready for reading (simply does a	844	Wait till the result filehandle becomes ready for reading (simply does a
644	C<select> on the filehandle. This is useful if you want to synchronously wait	845	C<select> on the filehandle. This is useful if you want to synchronously wait
645	for some requests to finish).	846	for some requests to finish).
646		847
647	See C<nreqs> for an example.	848	See C<nreqs> for an example.
648		849
649	=item IO::AIO::nreqs	850	=item IO::AIO::nreqs
650		851
651	Returns the number of requests currently outstanding (i.e. for which their	852	Returns the number of requests currently in the ready, execute or pending
652	callback has not been invoked yet).	853	states (i.e. for which their callback has not been invoked yet).
653		854
654	Example: wait till there are no outstanding requests anymore:	855	Example: wait till there are no outstanding requests anymore:
655		856
656	IO::AIO::poll_wait, IO::AIO::poll_cb	857	IO::AIO::poll_wait, IO::AIO::poll_cb
657	while IO::AIO::nreqs;	858	while IO::AIO::nreqs;
658		859
		860	=item IO::AIO::nready
		861
		862	Returns the number of requests currently in the ready state (not yet
		863	executed).
		864
		865	=item IO::AIO::npending
		866
		867	Returns the number of requests currently in the pending state (executed,
		868	but not yet processed by poll_cb).
		869
659	=item IO::AIO::flush	870	=item IO::AIO::flush
660		871
661	Wait till all outstanding AIO requests have been handled.	872	Wait till all outstanding AIO requests have been handled.
662		873
663	Strictly equivalent to:	874	Strictly equivalent to:
…		…
674	IO::AIO::poll_wait, IO::AIO::poll_cb	885	IO::AIO::poll_wait, IO::AIO::poll_cb
675	if IO::AIO::nreqs;	886	if IO::AIO::nreqs;
676		887
677	=item IO::AIO::min_parallel $nthreads	888	=item IO::AIO::min_parallel $nthreads
678		889
679	Set the minimum number of AIO threads to C<$nthreads>. The current default	890	Set the minimum number of AIO threads to C<$nthreads>. The current
680	is C<4>, which means four asynchronous operations can be done at one time	891	default is C<8>, which means eight asynchronous operations can execute
681	(the number of outstanding operations, however, is unlimited).	892	concurrently at any one time (the number of outstanding requests,
		893	however, is unlimited).
682		894
683	IO::AIO starts threads only on demand, when an AIO request is queued and	895	IO::AIO starts threads only on demand, when an AIO request is queued and
684	no free thread exists.	896	no free thread exists.
685		897
686	It is recommended to keep the number of threads low, as some Linux	898	It is recommended to keep the number of threads relatively low, as some
687	kernel versions will scale negatively with the number of threads (higher	899	Linux kernel versions will scale negatively with the number of threads
688	parallelity => MUCH higher latency). With current Linux 2.6 versions, 4-32	900	(higher parallelity => MUCH higher latency). With current Linux 2.6
689	threads should be fine.	901	versions, 4-32 threads should be fine.
690		902
691	Under most circumstances you don't need to call this function, as the	903	Under most circumstances you don't need to call this function, as the
692	module selects a default that is suitable for low to moderate load.	904	module selects a default that is suitable for low to moderate load.
693		905
694	=item IO::AIO::max_parallel $nthreads	906	=item IO::AIO::max_parallel $nthreads
…		…
703	This module automatically runs C<max_parallel 0> at program end, to ensure	915	This module automatically runs C<max_parallel 0> at program end, to ensure
704	that all threads are killed and that there are no outstanding requests.	916	that all threads are killed and that there are no outstanding requests.
705		917
706	Under normal circumstances you don't need to call this function.	918	Under normal circumstances you don't need to call this function.
707		919
708	=item $oldnreqs = IO::AIO::max_outstanding $nreqs	920	=item $oldmaxreqs = IO::AIO::max_outstanding $maxreqs
		921
		922	This is a very bad function to use in interactive programs because it
		923	blocks, and a bad way to reduce concurrency because it is inexact: Better
		924	use an C<aio_group> together with a feed callback.
709		925
710	Sets the maximum number of outstanding requests to C<$nreqs>. If you	926	Sets the maximum number of outstanding requests to C<$nreqs>. If you
711	try to queue up more than this number of requests, the caller will block until	927	to queue up more than this number of requests, the next call to the
712	some requests have been handled.	928	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
		929	function will block until the limit is no longer exceeded.
713		930
714	The default is very large, so normally there is no practical limit. If you	931	The default value is very large, so there is no practical limit on the
715	queue up many requests in a loop it often improves speed if you set	932	number of outstanding requests.
716	this to a relatively low number, such as C<100>.
717		933
718	Under normal circumstances you don't need to call this function.	934	You can still queue as many requests as you want. Therefore,
		935	C<max_oustsanding> is mainly useful in simple scripts (with low values) or
		936	as a stop gap to shield against fatal memory overflow (with large values).
719		937
720	=back	938	=back
721		939
722	=cut	940	=cut
723		941
…		…
735	or return undef;	953	or return undef;
736		954
737	*$sym	955	*$sym
738	}	956	}
739		957
740	min_parallel 4;	958	min_parallel 8;
741
742	END {
743	max_parallel 0;
744	}
745		959
746	1;	960	1;
747		961
748	=head2 FORK BEHAVIOUR	962	=head2 FORK BEHAVIOUR
749		963
750	This module should do "the right thing" when the process using it forks:	964	This module should do "the right thing" when the process using it forks:
751		965
752	Before the fork, IO::AIO enters a quiescent state where no requests	966	Before the fork, IO::AIO enters a quiescent state where no requests
753	can be added in other threads and no results will be processed. After	967	can be added in other threads and no results will be processed. After
754	the fork the parent simply leaves the quiescent state and continues	968	the fork the parent simply leaves the quiescent state and continues
755	request/result processing, while the child clears the request/result	969	request/result processing, while the child frees the request/result queue
756	queue (so the requests started before the fork will only be handled in	970	(so that the requests started before the fork will only be handled in the
757	the parent). Threads will be started on demand until the limit ste in the	971	parent). Threads will be started on demand until the limit set in the
758	parent process has been reached again.	972	parent process has been reached again.
759		973
760	In short: the parent will, after a short pause, continue as if fork had	974	In short: the parent will, after a short pause, continue as if fork had
761	not been called, while the child will act as if IO::AIO has not been used	975	not been called, while the child will act as if IO::AIO has not been used
762	yet.	976	yet.
763		977
		978	=head2 MEMORY USAGE
		979
		980	Per-request usage:
		981
		982	Each aio request uses - depending on your architecture - around 100-200
		983	bytes of memory. In addition, stat requests need a stat buffer (possibly
		984	a few hundred bytes), readdir requires a result buffer and so on. Perl
		985	scalars and other data passed into aio requests will also be locked and
		986	will consume memory till the request has entered the done state.
		987
		988	This is now awfully much, so queuing lots of requests is not usually a
		989	problem.
		990
		991	Per-thread usage:
		992
		993	In the execution phase, some aio requests require more memory for
		994	temporary buffers, and each thread requires a stack and other data
		995	structures (usually around 16k-128k, depending on the OS).
		996
		997	=head1 KNOWN BUGS
		998
		999	Known bugs will be fixed in the next release.
		1000
764	=head1 SEE ALSO	1001	=head1 SEE ALSO
765		1002
766	L<Coro>, L<Linux::AIO> (obsolete).	1003	L<Coro::AIO>.
767		1004
768	=head1 AUTHOR	1005	=head1 AUTHOR
769		1006
770	Marc Lehmann <schmorp@schmorp.de>	1007	Marc Lehmann <schmorp@schmorp.de>
771	http://home.schmorp.de/	1008	http://home.schmorp.de/

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Comparing IO-AIO/AIO.pm (file contents): Revision 1.55 by root, Sun Oct 22 00:49:29 2006 UTC vs. Revision 1.81 by root, Fri Oct 27 19:17:23 2006 UTC

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Revision 1.55 by root, Sun Oct 22 00:49:29 2006 UTC vs.
Revision 1.81 by root, Fri Oct 27 19:17:23 2006 UTC