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

Comparing IO-AIO/AIO.pm (file contents):
Revision 1.70 by root, Tue Oct 24 03:40:38 2006 UTC vs.
Revision 1.85 by root, Sat Oct 28 01:40:30 2006 UTC

…		…
51	=head1 DESCRIPTION	51	=head1 DESCRIPTION
52		52
53	This module implements asynchronous I/O using whatever means your	53	This module implements asynchronous I/O using whatever means your
54	operating system supports.	54	operating system supports.
55		55
		56	Asynchronous means that operations that can normally block your program
		57	(e.g. reading from disk) will be done asynchronously: the operation
		58	will still block, but you can do something else in the meantime. This
		59	is extremely useful for programs that need to stay interactive even
		60	when doing heavy I/O (GUI programs, high performance network servers
		61	etc.), but can also be used to easily do operations in parallel that are
		62	normally done sequentially, e.g. stat'ing many files, which is much faster
		63	on a RAID volume or over NFS when you do a number of stat operations
		64	concurrently.
		65
		66	While this works on all types of file descriptors (for example sockets),
		67	using these functions on file descriptors that support nonblocking
		68	operation (again, sockets, pipes etc.) is very inefficient. Use an event
		69	loop for that (such as the L<Event\|Event> module): IO::AIO will naturally
		70	fit into such an event loop itself.
		71
56	Currently, a number of threads are started that execute your read/writes	72	In this version, a number of threads are started that execute your
57	and signal their completion. You don't need thread support in perl, and	73	requests and signal their completion. You don't need thread support
58	the threads created by this module will not be visible to perl. In the	74	in perl, and the threads created by this module will not be visible
59	future, this module might make use of the native aio functions available	75	to perl. In the future, this module might make use of the native aio
60	on many operating systems. However, they are often not well-supported	76	functions available on many operating systems. However, they are often
61	(Linux doesn't allow them on normal files currently, for example),	77	not well-supported or restricted (GNU/Linux doesn't allow them on normal
62	and they would only support aio_read and aio_write, so the remaining	78	files currently, for example), and they would only support aio_read and
63	functionality would have to be implemented using threads anyway.	79	aio_write, so the remaining functionality would have to be implemented
		80	using threads anyway.
64		81
65	Although the module will work with in the presence of other threads,	82	Although the module will work with in the presence of other (Perl-)
66	it is currently not reentrant in any way, so use appropriate locking	83	threads, it is currently not reentrant in any way, so use appropriate
67	yourself, always call C<poll_cb> from within the same thread, or never	84	locking yourself, always call C<poll_cb> from within the same thread, or
68	call C<poll_cb> (or other C<aio_> functions) recursively.	85	never call C<poll_cb> (or other C<aio_> functions) recursively.
		86
		87	=head1 REQUEST ANATOMY AND LIFETIME
		88
		89	Every C<aio_*> function creates a request. which is a C data structure not
		90	directly visible to Perl.
		91
		92	If called in non-void context, every request function returns a Perl
		93	object representing the request. In void context, nothing is returned,
		94	which saves a bit of memory.
		95
		96	The perl object is a fairly standard ref-to-hash object. The hash contents
		97	are not used by IO::AIO so you are free to store anything you like in it.
		98
		99	During their existance, aio requests travel through the following states,
		100	in order:
		101
		102	=over 4
		103
		104	=item ready
		105
		106	Immediately after a request is created it is put into the ready state,
		107	waiting for a thread to execute it.
		108
		109	=item execute
		110
		111	A thread has accepted the request for processing and is currently
		112	executing it (e.g. blocking in read).
		113
		114	=item pending
		115
		116	The request has been executed and is waiting for result processing.
		117
		118	While request submission and execution is fully asynchronous, result
		119	processing is not and relies on the perl interpreter calling C<poll_cb>
		120	(or another function with the same effect).
		121
		122	=item result
		123
		124	The request results are processed synchronously by C<poll_cb>.
		125
		126	The C<poll_cb> function will process all outstanding aio requests by
		127	calling their callbacks, freeing memory associated with them and managing
		128	any groups they are contained in.
		129
		130	=item done
		131
		132	Request has reached the end of its lifetime and holds no resources anymore
		133	(except possibly for the Perl object, but its connection to the actual
		134	aio request is severed and calling its methods will either do nothing or
		135	result in a runtime error).
69		136
70	=cut	137	=cut
71		138
72	package IO::AIO;	139	package IO::AIO;
73		140
…		…
80	our $VERSION = '2.0';	147	our $VERSION = '2.0';
81		148
82	our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close aio_stat	149	our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close aio_stat
83	aio_lstat aio_unlink aio_rmdir aio_readdir aio_scandir aio_symlink	150	aio_lstat aio_unlink aio_rmdir aio_readdir aio_scandir aio_symlink
84	aio_fsync aio_fdatasync aio_readahead aio_rename aio_link aio_move	151	aio_fsync aio_fdatasync aio_readahead aio_rename aio_link aio_move
85	aio_group aio_nop);	152	aio_copy aio_group aio_nop aio_mknod);
86	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));	153	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
87	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush	154	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
88	min_parallel max_parallel max_outstanding nreqs);	155	min_parallel max_parallel nreqs nready npending);
89		156
90	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';	157	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';
91		158
92	require XSLoader;	159	require XSLoader;
93	XSLoader::load ("IO::AIO", $VERSION);	160	XSLoader::load ("IO::AIO", $VERSION);
…		…
124	environment, d) use Glib::filename_from_unicode on unicode filenames or e)	191	environment, d) use Glib::filename_from_unicode on unicode filenames or e)
125	use something else.	192	use something else.
126		193
127	=over 4	194	=over 4
128		195
129	=item aioreq_pri $pri	196	=item $prev_pri = aioreq_pri [$pri]
130		197
131	Sets the priority for the next aio request. The default priority	198	Returns the priority value that would be used for the next request and, if
		199	C<$pri> is given, sets the priority for the next aio request.
		200
132	is C<0>, the minimum and maximum priorities are C<-4> and C<4>,	201	The default priority is C<0>, the minimum and maximum priorities are C<-4>
133	respectively. Requests with higher priority will be serviced first.	202	and C<4>, respectively. Requests with higher priority will be serviced
		203	first.
134		204
135	The priority will be reset to C<0> after each call to one of the C<aio_>	205	The priority will be reset to C<0> after each call to one of the C<aio_*>
136	functions.	206	functions.
137		207
138	Example: open a file with low priority, then read something from it with	208	Example: open a file with low priority, then read something from it with
139	higher priority so the read request is serviced before other low priority	209	higher priority so the read request is serviced before other low priority
140	open requests (potentially spamming the cache):	210	open requests (potentially spamming the cache):
…		…
210		280
211	aio_read $fh, 7, 15, $buffer, 0, sub {	281	aio_read $fh, 7, 15, $buffer, 0, sub {
212	$_[0] > 0 or die "read error: $!";	282	$_[0] > 0 or die "read error: $!";
213	print "read $_[0] bytes: <$buffer>\n";	283	print "read $_[0] bytes: <$buffer>\n";
214	};	284	};
215
216	=item aio_move $srcpath, $dstpath, $callback->($status)
217
218	[EXPERIMENTAL due to internal aio_group use]
219
220	Try to move the I<file> (directories not supported as either source or
221	destination) from C<$srcpath> to C<$dstpath> and call the callback with
222	the C<0> (error) or C<-1> ok.
223
224	This is a composite request that tries to rename(2) the file first. If
225	rename files with C<EXDEV>, it creates the destination file with mode 0200
226	and copies the contents of the source file into it using C<aio_sendfile>,
227	followed by restoring atime, mtime, access mode and uid/gid, in that
228	order, and unlinking the C<$srcpath>.
229
230	If an error occurs, the partial destination file will be unlinked, if
231	possible, except when setting atime, mtime, access mode and uid/gid, where
232	errors are being ignored.
233
234	=cut
235
236	sub aio_move($$$) {
237	my ($src, $dst, $cb) = @_;
238
239	my $grp = aio_group $cb;
240
241	add $grp aio_rename $src, $dst, sub {
242	if ($_[0] && $! == EXDEV) {
243	add $grp aio_open $src, O_RDONLY, 0, sub {
244	if (my $src_fh = $_[0]) {
245	my @stat = stat $src_fh;
246
247	add $grp aio_open $dst, O_WRONLY, 0200, sub {
248	if (my $dst_fh = $_[0]) {
249	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
250	close $src_fh;
251
252	if ($_[0] == $stat[7]) {
253	utime $stat[8], $stat[9], $dst;
254	chmod $stat[2] & 07777, $dst_fh;
255	chown $stat[4], $stat[5], $dst_fh;
256	close $dst_fh;
257
258	add $grp aio_unlink $src, sub {
259	$grp->result ($_[0]);
260	};
261	} else {
262	my $errno = $!;
263	add $grp aio_unlink $dst, sub {
264	$! = $errno;
265	$grp->result (-1);
266	};
267	}
268	};
269	} else {
270	$grp->result (-1);
271	}
272	},
273
274	} else {
275	$grp->result (-1);
276	}
277	};
278	} else {
279	$grp->result ($_[0]);
280	}
281	};
282
283	$grp
284	}
285		285
286	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)	286	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
287		287
288	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts	288	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
289	reading at byte offset C<$in_offset>, and starts writing at the current	289	reading at byte offset C<$in_offset>, and starts writing at the current
…		…
345	=item aio_unlink $pathname, $callback->($status)	345	=item aio_unlink $pathname, $callback->($status)
346		346
347	Asynchronously unlink (delete) a file and call the callback with the	347	Asynchronously unlink (delete) a file and call the callback with the
348	result code.	348	result code.
349		349
		350	=item aio_mknod $path, $mode, $dev, $callback->($status)
		351
		352	Asynchronously create a device node (or fifo). See mknod(2).
		353
		354	The only portable (POSIX) way of calling this function is:
		355
		356	aio_mknod $path, IO::AIO::S_IFIFO \| $mode, 0, sub { ...
		357
350	=item aio_link $srcpath, $dstpath, $callback->($status)	358	=item aio_link $srcpath, $dstpath, $callback->($status)
351		359
352	Asynchronously create a new link to the existing object at C<$srcpath> at	360	Asynchronously create a new link to the existing object at C<$srcpath> at
353	the path C<$dstpath> and call the callback with the result code.	361	the path C<$dstpath> and call the callback with the result code.
354		362
…		…
374	sorted, and will B<NOT> include the C<.> and C<..> entries.	382	sorted, and will B<NOT> include the C<.> and C<..> entries.
375		383
376	The callback a single argument which is either C<undef> or an array-ref	384	The callback a single argument which is either C<undef> or an array-ref
377	with the filenames.	385	with the filenames.
378		386
		387	=item aio_copy $srcpath, $dstpath, $callback->($status)
		388
		389	Try to copy the I<file> (directories not supported as either source or
		390	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		391	the C<0> (error) or C<-1> ok.
		392
		393	This is a composite request that it creates the destination file with
		394	mode 0200 and copies the contents of the source file into it using
		395	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
		396	uid/gid, in that order.
		397
		398	If an error occurs, the partial destination file will be unlinked, if
		399	possible, except when setting atime, mtime, access mode and uid/gid, where
		400	errors are being ignored.
		401
		402	=cut
		403
		404	sub aio_copy($$;$) {
		405	my ($src, $dst, $cb) = @_;
		406
		407	my $pri = aioreq_pri;
		408	my $grp = aio_group $cb;
		409
		410	aioreq_pri $pri;
		411	add $grp aio_open $src, O_RDONLY, 0, sub {
		412	if (my $src_fh = $_[0]) {
		413	my @stat = stat $src_fh;
		414
		415	aioreq_pri $pri;
		416	add $grp aio_open $dst, O_CREAT \| O_WRONLY \| O_TRUNC, 0200, sub {
		417	if (my $dst_fh = $_[0]) {
		418	aioreq_pri $pri;
		419	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
		420	if ($_[0] == $stat[7]) {
		421	$grp->result (0);
		422	close $src_fh;
		423
		424	# those should not normally block. should. should.
		425	utime $stat[8], $stat[9], $dst;
		426	chmod $stat[2] & 07777, $dst_fh;
		427	chown $stat[4], $stat[5], $dst_fh;
		428	close $dst_fh;
		429	} else {
		430	$grp->result (-1);
		431	close $src_fh;
		432	close $dst_fh;
		433
		434	aioreq $pri;
		435	add $grp aio_unlink $dst;
		436	}
		437	};
		438	} else {
		439	$grp->result (-1);
		440	}
		441	},
		442
		443	} else {
		444	$grp->result (-1);
		445	}
		446	};
		447
		448	$grp
		449	}
		450
		451	=item aio_move $srcpath, $dstpath, $callback->($status)
		452
		453	Try to move the I<file> (directories not supported as either source or
		454	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		455	the C<0> (error) or C<-1> ok.
		456
		457	This is a composite request that tries to rename(2) the file first. If
		458	rename files with C<EXDEV>, it copies the file with C<aio_copy> and, if
		459	that is successful, unlinking the C<$srcpath>.
		460
		461	=cut
		462
		463	sub aio_move($$;$) {
		464	my ($src, $dst, $cb) = @_;
		465
		466	my $pri = aioreq_pri;
		467	my $grp = aio_group $cb;
		468
		469	aioreq_pri $pri;
		470	add $grp aio_rename $src, $dst, sub {
		471	if ($_[0] && $! == EXDEV) {
		472	aioreq_pri $pri;
		473	add $grp aio_copy $src, $dst, sub {
		474	$grp->result ($_[0]);
		475
		476	if (!$_[0]) {
		477	aioreq_pri $pri;
		478	add $grp aio_unlink $src;
		479	}
		480	};
		481	} else {
		482	$grp->result ($_[0]);
		483	}
		484	};
		485
		486	$grp
		487	}
		488
379	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	489	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
380		490
381	[EXPERIMENTAL due to internal aio_group use]
382
383	Scans a directory (similar to C<aio_readdir>) but additionally tries to	491	Scans a directory (similar to C<aio_readdir>) but additionally tries to
384	separate the entries of directory C<$path> into two sets of names, ones	492	efficiently separate the entries of directory C<$path> into two sets of
385	you can recurse into (directories or links to them), and ones you cannot	493	names, directories you can recurse into (directories), and ones you cannot
386	recurse into (everything else).	494	recurse into (everything else, including symlinks to directories).
387		495
388	C<aio_scandir> is a composite request that creates of many sub requests_	496	C<aio_scandir> is a composite request that creates of many sub requests_
389	C<$maxreq> specifies the maximum number of outstanding aio requests that	497	C<$maxreq> specifies the maximum number of outstanding aio requests that
390	this function generates. If it is C<< <= 0 >>, then a suitable default	498	this function generates. If it is C<< <= 0 >>, then a suitable default
391	will be chosen (currently 6).	499	will be chosen (currently 4).
392		500
393	On error, the callback is called without arguments, otherwise it receives	501	On error, the callback is called without arguments, otherwise it receives
394	two array-refs with path-relative entry names.	502	two array-refs with path-relative entry names.
395		503
396	Example:	504	Example:
…		…
433	=cut	541	=cut
434		542
435	sub aio_scandir($$$) {	543	sub aio_scandir($$$) {
436	my ($path, $maxreq, $cb) = @_;	544	my ($path, $maxreq, $cb) = @_;
437		545
		546	my $pri = aioreq_pri;
		547
438	my $grp = aio_group $cb;	548	my $grp = aio_group $cb;
439		549
440	$maxreq = 6 if $maxreq <= 0;	550	$maxreq = 4 if $maxreq <= 0;
441		551
442	# stat once	552	# stat once
		553	aioreq_pri $pri;
443	add $grp aio_stat $path, sub {	554	add $grp aio_stat $path, sub {
444	return $grp->result () if $_[0];	555	return $grp->result () if $_[0];
445	my $now = time;	556	my $now = time;
446	my $hash1 = join ":", (stat _)[0,1,3,7,9];	557	my $hash1 = join ":", (stat _)[0,1,3,7,9];
447		558
448	# read the directory entries	559	# read the directory entries
		560	aioreq_pri $pri;
449	add $grp aio_readdir $path, sub {	561	add $grp aio_readdir $path, sub {
450	my $entries = shift	562	my $entries = shift
451	or return $grp->result ();	563	or return $grp->result ();
452		564
453	# stat the dir another time	565	# stat the dir another time
		566	aioreq_pri $pri;
454	add $grp aio_stat $path, sub {	567	add $grp aio_stat $path, sub {
455	my $hash2 = join ":", (stat _)[0,1,3,7,9];	568	my $hash2 = join ":", (stat _)[0,1,3,7,9];
456		569
457	my $ndirs;	570	my $ndirs;
458		571
…		…
473	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],	586	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
474	@$entries];	587	@$entries];
475		588
476	my (@dirs, @nondirs);	589	my (@dirs, @nondirs);
477		590
478	my ($statcb, $schedcb);
479	my $nreq = 0;
480
481	my $statgrp = add $grp aio_group;	591	my $statgrp = add $grp aio_group sub {
		592	$grp->result (\@dirs, \@nondirs);
		593	};
482		594
483	$schedcb = sub {	595	limit $statgrp $maxreq;
484	if (@$entries) {	596	feed $statgrp sub {
485	if ($nreq < $maxreq) {	597	return unless @$entries;
486	my $ent = pop @$entries;	598	my $entry = pop @$entries;
		599
		600	aioreq_pri $pri;
		601	add $statgrp aio_stat "$path/$entry/.", sub {
		602	if ($_[0] < 0) {
		603	push @nondirs, $entry;
		604	} else {
		605	# need to check for real directory
		606	aioreq_pri $pri;
		607	add $statgrp aio_lstat "$path/$entry", sub {
		608	if (-d _) {
		609	push @dirs, $entry;
		610
		611	unless (--$ndirs) {
		612	push @nondirs, @$entries;
		613	feed $statgrp;
		614	}
		615	} else {
		616	push @nondirs, $entry;
		617	}
487	$nreq++;	618	}
488	add $statgrp aio_stat "$path/$ent/.", sub { $statcb->($_[0], $ent) };
489	}	619	}
490	} elsif (!$nreq) {
491	# finished
492	$statgrp->cancel;
493	undef $statcb;
494	undef $schedcb;
495	$grp->result (\@dirs, \@nondirs);
496	}	620	};
497	};	621	};
498	$statcb = sub {
499	my ($status, $entry) = @_;
500
501	if ($status < 0) {
502	$nreq--;
503	push @nondirs, $entry;
504	&$schedcb;
505	} else {
506	# need to check for real directory
507	add $grp aio_lstat "$path/$entry", sub {
508	$nreq--;
509
510	if (-d _) {
511	push @dirs, $entry;
512
513	if (!--$ndirs) {
514	push @nondirs, @$entries;
515	$entries = [];
516	}
517	} else {
518	push @nondirs, $entry;
519	}
520
521	&$schedcb;
522	}
523	}
524	};
525
526	&$schedcb while @$entries && $nreq < $maxreq;
527	};	622	};
528	};	623	};
529	};	624	};
530		625
531	$grp	626	$grp
…		…
544	If this call isn't available because your OS lacks it or it couldn't be	639	If this call isn't available because your OS lacks it or it couldn't be
545	detected, it will be emulated by calling C<fsync> instead.	640	detected, it will be emulated by calling C<fsync> instead.
546		641
547	=item aio_group $callback->(...)	642	=item aio_group $callback->(...)
548		643
549	[EXPERIMENTAL]
550
551	This is a very special aio request: Instead of doing something, it is a	644	This is a very special aio request: Instead of doing something, it is a
552	container for other aio requests, which is useful if you want to bundle	645	container for other aio requests, which is useful if you want to bundle
553	many requests into a single, composite, request.	646	many requests into a single, composite, request with a definite callback
		647	and the ability to cancel the whole request with its subrequests.
554		648
555	Returns an object of class L<IO::AIO::GRP>. See its documentation below	649	Returns an object of class L<IO::AIO::GRP>. See its documentation below
556	for more info.	650	for more info.
557		651
558	Example:	652	Example:
…		…
577	phase and still requires a worker thread. Thus, the callback will not	671	phase and still requires a worker thread. Thus, the callback will not
578	be executed immediately but only after other requests in the queue have	672	be executed immediately but only after other requests in the queue have
579	entered their execution phase. This can be used to measure request	673	entered their execution phase. This can be used to measure request
580	latency.	674	latency.
581		675
582	=item IO::AIO::aio_sleep $fractional_seconds, $callback->() NOT EXPORTED	676	=item IO::AIO::aio_busy $fractional_seconds, $callback->() NOT EXPORTED
583		677
584	Mainly used for debugging and benchmarking, this aio request puts one of	678	Mainly used for debugging and benchmarking, this aio request puts one of
585	the request workers to sleep for the given time.	679	the request workers to sleep for the given time.
586		680
587	While it is theoretically handy to have simple I/O scheduling requests	681	While it is theoretically handy to have simple I/O scheduling requests
588	like sleep and file handle readable/writable, the overhead this creates	682	like sleep and file handle readable/writable, the overhead this creates is
589	is immense, so do not use this function except to put your application	683	immense (it blocks a thread for a long time) so do not use this function
590	under artificial I/O pressure.	684	except to put your application under artificial I/O pressure.
591		685
592	=back	686	=back
593		687
594	=head2 IO::AIO::REQ CLASS	688	=head2 IO::AIO::REQ CLASS
595		689
596	All non-aggregate C<aio_*> functions return an object of this class when	690	All non-aggregate C<aio_*> functions return an object of this class when
597	called in non-void context.	691	called in non-void context.
598
599	A request always moves through the following five states in its lifetime,
600	in order: B<ready> (request has been created, but has not been executed
601	yet), B<execute> (request is currently being executed), B<pending>
602	(request has been executed but callback has not been called yet),
603	B<result> (results are being processed synchronously, includes calling the
604	callback) and B<done> (request has reached the end of its lifetime and
605	holds no resources anymore).
606		692
607	=over 4	693	=over 4
608		694
609	=item cancel $req	695	=item cancel $req
610		696
…		…
664	=item * They can also can also be added to other IO::AIO::GRP objects.	750	=item * They can also can also be added to other IO::AIO::GRP objects.
665		751
666	=item * You must not add requests to a group from within the group callback (or	752	=item * You must not add requests to a group from within the group callback (or
667	any later time).	753	any later time).
668		754
669	=item * This does not harmonise well with C<max_outstanding>, so best do
670	not combine C<aio_group> with it. Groups and feeders are recommended for
671	this kind of concurrency-limiting.
672
673	=back	755	=back
674		756
675	Their lifetime, simplified, looks like this: when they are empty, they	757	Their lifetime, simplified, looks like this: when they are empty, they
676	will finish very quickly. If they contain only requests that are in the	758	will finish very quickly. If they contain only requests that are in the
677	C<done> state, they will also finish. Otherwise they will continue to	759	C<done> state, they will also finish. Otherwise they will continue to
…		…
692	be added, including other groups, as long as you do not create circular	774	be added, including other groups, as long as you do not create circular
693	dependencies.	775	dependencies.
694		776
695	Returns all its arguments.	777	Returns all its arguments.
696		778
		779	=item $grp->cancel_subs
		780
		781	Cancel all subrequests and clears any feeder, but not the group request
		782	itself. Useful when you queued a lot of events but got a result early.
		783
697	=item $grp->result (...)	784	=item $grp->result (...)
698		785
699	Set the result value(s) that will be passed to the group callback when all	786	Set the result value(s) that will be passed to the group callback when all
700	subrequests have finished. By default, no argument will be passed.	787	subrequests have finished and set thre groups errno to the current value
		788	of errno (just like calling C<errno> without an error number). By default,
		789	no argument will be passed and errno is zero.
		790
		791	=item $grp->errno ([$errno])
		792
		793	Sets the group errno value to C<$errno>, or the current value of errno
		794	when the argument is missing.
		795
		796	Every aio request has an associated errno value that is restored when
		797	the callback is invoked. This method lets you change this value from its
		798	default (0).
		799
		800	Calling C<result> will also set errno, so make sure you either set C<$!>
		801	before the call to C<result>, or call c<errno> after it.
701		802
702	=item feed $grp $callback->($grp)	803	=item feed $grp $callback->($grp)
703
704	[VERY EXPERIMENTAL]
705		804
706	Sets a feeder/generator on this group: every group can have an attached	805	Sets a feeder/generator on this group: every group can have an attached
707	generator that generates requests if idle. The idea behind this is that,	806	generator that generates requests if idle. The idea behind this is that,
708	although you could just queue as many requests as you want in a group,	807	although you could just queue as many requests as you want in a group,
709	this might starve other requests for a potentially long time. For	808	this might starve other requests for a potentially long time. For
…		…
763		862
764	Process all outstanding events on the result pipe. You have to call this	863	Process all outstanding events on the result pipe. You have to call this
765	regularly. Returns the number of events processed. Returns immediately	864	regularly. Returns the number of events processed. Returns immediately
766	when no events are outstanding.	865	when no events are outstanding.
767		866
		867	If not all requests were processed for whatever reason, the filehandle
		868	will still be ready when C<poll_cb> returns.
		869
768	Example: Install an Event watcher that automatically calls	870	Example: Install an Event watcher that automatically calls
769	IO::AIO::poll_cb with high priority:	871	IO::AIO::poll_cb with high priority:
770		872
771	Event->io (fd => IO::AIO::poll_fileno,	873	Event->io (fd => IO::AIO::poll_fileno,
772	poll => 'r', async => 1,	874	poll => 'r', async => 1,
773	cb => \&IO::AIO::poll_cb);	875	cb => \&IO::AIO::poll_cb);
774		876
		877	=item IO::AIO::poll_some $max_requests
		878
		879	Similar to C<poll_cb>, but only processes up to C<$max_requests> requests
		880	at a time.
		881
		882	Useful if you want to ensure some level of interactiveness when perl is
		883	not fast enough to process all requests in time.
		884
		885	Example: Install an Event watcher that automatically calls
		886	IO::AIO::poll_some with low priority, to ensure that other parts of the
		887	program get the CPU sometimes even under high AIO load.
		888
		889	Event->io (fd => IO::AIO::poll_fileno,
		890	poll => 'r', nice => 1,
		891	cb => sub { IO::AIO::poll_some 256 });
		892
775	=item IO::AIO::poll_wait	893	=item IO::AIO::poll_wait
776		894
777	Wait till the result filehandle becomes ready for reading (simply does a	895	Wait till the result filehandle becomes ready for reading (simply does a
778	C<select> on the filehandle. This is useful if you want to synchronously wait	896	C<select> on the filehandle. This is useful if you want to synchronously wait
779	for some requests to finish).	897	for some requests to finish).
780		898
781	See C<nreqs> for an example.	899	See C<nreqs> for an example.
782		900
783	=item IO::AIO::nreqs	901	=item IO::AIO::nreqs
784		902
785	Returns the number of requests currently outstanding (i.e. for which their	903	Returns the number of requests currently in the ready, execute or pending
786	callback has not been invoked yet).	904	states (i.e. for which their callback has not been invoked yet).
787		905
788	Example: wait till there are no outstanding requests anymore:	906	Example: wait till there are no outstanding requests anymore:
789		907
790	IO::AIO::poll_wait, IO::AIO::poll_cb	908	IO::AIO::poll_wait, IO::AIO::poll_cb
791	while IO::AIO::nreqs;	909	while IO::AIO::nreqs;
		910
		911	=item IO::AIO::nready
		912
		913	Returns the number of requests currently in the ready state (not yet
		914	executed).
		915
		916	=item IO::AIO::npending
		917
		918	Returns the number of requests currently in the pending state (executed,
		919	but not yet processed by poll_cb).
792		920
793	=item IO::AIO::flush	921	=item IO::AIO::flush
794		922
795	Wait till all outstanding AIO requests have been handled.	923	Wait till all outstanding AIO requests have been handled.
796		924
…		…
838	This module automatically runs C<max_parallel 0> at program end, to ensure	966	This module automatically runs C<max_parallel 0> at program end, to ensure
839	that all threads are killed and that there are no outstanding requests.	967	that all threads are killed and that there are no outstanding requests.
840		968
841	Under normal circumstances you don't need to call this function.	969	Under normal circumstances you don't need to call this function.
842		970
843	=item $oldnreqs = IO::AIO::max_outstanding $nreqs	971	=item $oldmaxreqs = IO::AIO::max_outstanding $maxreqs
844		972
845	[DEPRECATED]	973	This is a very bad function to use in interactive programs because it
		974	blocks, and a bad way to reduce concurrency because it is inexact: Better
		975	use an C<aio_group> together with a feed callback.
846		976
847	Sets the maximum number of outstanding requests to C<$nreqs>. If you	977	Sets the maximum number of outstanding requests to C<$nreqs>. If you
848	try to queue up more than this number of requests, the caller will block until	978	to queue up more than this number of requests, the next call to the
849	some requests have been handled.	979	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
		980	function will block until the limit is no longer exceeded.
850		981
851	The default is very large, so normally there is no practical limit. If you	982	The default value is very large, so there is no practical limit on the
852	queue up many requests in a loop it often improves speed if you set	983	number of outstanding requests.
853	this to a relatively low number, such as C<100>.
854		984
855	This function does not work well together with C<aio_group>'s, and their	985	You can still queue as many requests as you want. Therefore,
856	feeder interface is better suited to limiting concurrency, so do not use	986	C<max_oustsanding> is mainly useful in simple scripts (with low values) or
857	this function.	987	as a stop gap to shield against fatal memory overflow (with large values).
858
859	Under normal circumstances you don't need to call this function.
860		988
861	=back	989	=back
862		990
863	=cut	991	=cut
864		992
…		…
879	}	1007	}
880		1008
881	min_parallel 8;	1009	min_parallel 8;
882		1010
883	END {	1011	END {
884	max_parallel 0;	1012	min_parallel 1;
885	}	1013	flush;
		1014	};
886		1015
887	1;	1016	1;
888		1017
889	=head2 FORK BEHAVIOUR	1018	=head2 FORK BEHAVIOUR
890		1019
891	This module should do "the right thing" when the process using it forks:	1020	This module should do "the right thing" when the process using it forks:
892		1021
893	Before the fork, IO::AIO enters a quiescent state where no requests	1022	Before the fork, IO::AIO enters a quiescent state where no requests
894	can be added in other threads and no results will be processed. After	1023	can be added in other threads and no results will be processed. After
895	the fork the parent simply leaves the quiescent state and continues	1024	the fork the parent simply leaves the quiescent state and continues
896	request/result processing, while the child clears the request/result	1025	request/result processing, while the child frees the request/result queue
897	queue (so the requests started before the fork will only be handled in	1026	(so that the requests started before the fork will only be handled in the
898	the parent). Threads will be started on demand until the limit ste in the	1027	parent). Threads will be started on demand until the limit set in the
899	parent process has been reached again.	1028	parent process has been reached again.
900		1029
901	In short: the parent will, after a short pause, continue as if fork had	1030	In short: the parent will, after a short pause, continue as if fork had
902	not been called, while the child will act as if IO::AIO has not been used	1031	not been called, while the child will act as if IO::AIO has not been used
903	yet.	1032	yet.
904		1033
905	=head2 MEMORY USAGE	1034	=head2 MEMORY USAGE
906		1035
		1036	Per-request usage:
		1037
907	Each aio request uses - depending on your architecture - around 128 bytes	1038	Each aio request uses - depending on your architecture - around 100-200
908	of memory. In addition, stat requests need a stat buffer (possibly a few	1039	bytes of memory. In addition, stat requests need a stat buffer (possibly
909	hundred bytes). Perl scalars and other data passed into aio requests will	1040	a few hundred bytes), readdir requires a result buffer and so on. Perl
910	also be locked.	1041	scalars and other data passed into aio requests will also be locked and
		1042	will consume memory till the request has entered the done state.
911		1043
912	This is now awfully much, so queuing lots of requests is not usually a	1044	This is now awfully much, so queuing lots of requests is not usually a
913	problem.	1045	problem.
914		1046
915	Each thread needs a stack area which is usually around 16k, sometimes much	1047	Per-thread usage:
916	larger, depending on the OS.	1048
		1049	In the execution phase, some aio requests require more memory for
		1050	temporary buffers, and each thread requires a stack and other data
		1051	structures (usually around 16k-128k, depending on the OS).
		1052
		1053	=head1 KNOWN BUGS
		1054
		1055	Known bugs will be fixed in the next release.
917		1056
918	=head1 SEE ALSO	1057	=head1 SEE ALSO
919		1058
920	L<Coro::AIO>.	1059	L<Coro::AIO>.
921		1060

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Comparing IO-AIO/AIO.pm (file contents): Revision 1.70 by root, Tue Oct 24 03:40:38 2006 UTC vs. Revision 1.85 by root, Sat Oct 28 01:40:30 2006 UTC

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Comparing IO-AIO/AIO.pm (file contents):
Revision 1.70 by root, Tue Oct 24 03:40:38 2006 UTC vs.
Revision 1.85 by root, Sat Oct 28 01:40:30 2006 UTC