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

Comparing IO-AIO/AIO.pm (file contents):
Revision 1.68 by root, Tue Oct 24 03:17:39 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));	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.
		207
		208	Example: open a file with low priority, then read something from it with
		209	higher priority so the read request is serviced before other low priority
		210	open requests (potentially spamming the cache):
		211
		212	aioreq_pri -3;
		213	aio_open ..., sub {
		214	return unless $_[0];
		215
		216	aioreq_pri -2;
		217	aio_read $_[0], ..., sub {
		218	...
		219	};
		220	};
		221
		222	=item aioreq_nice $pri_adjust
		223
		224	Similar to C<aioreq_pri>, but subtracts the given value from the current
		225	priority, so effects are cumulative.
137		226
138	=item aio_open $pathname, $flags, $mode, $callback->($fh)	227	=item aio_open $pathname, $flags, $mode, $callback->($fh)
139		228
140	Asynchronously open or create a file and call the callback with a newly	229	Asynchronously open or create a file and call the callback with a newly
141	created filehandle for the file.	230	created filehandle for the file.
…		…
191		280
192	aio_read $fh, 7, 15, $buffer, 0, sub {	281	aio_read $fh, 7, 15, $buffer, 0, sub {
193	$_[0] > 0 or die "read error: $!";	282	$_[0] > 0 or die "read error: $!";
194	print "read $_[0] bytes: <$buffer>\n";	283	print "read $_[0] bytes: <$buffer>\n";
195	};	284	};
196
197	=item aio_move $srcpath, $dstpath, $callback->($status)
198
199	[EXPERIMENTAL due to internal aio_group use]
200
201	Try to move the I<file> (directories not supported as either source or
202	destination) from C<$srcpath> to C<$dstpath> and call the callback with
203	the C<0> (error) or C<-1> ok.
204
205	This is a composite request that tries to rename(2) the file first. If
206	rename files with C<EXDEV>, it creates the destination file with mode 0200
207	and copies the contents of the source file into it using C<aio_sendfile>,
208	followed by restoring atime, mtime, access mode and uid/gid, in that
209	order, and unlinking the C<$srcpath>.
210
211	If an error occurs, the partial destination file will be unlinked, if
212	possible, except when setting atime, mtime, access mode and uid/gid, where
213	errors are being ignored.
214
215	=cut
216
217	sub aio_move($$$) {
218	my ($src, $dst, $cb) = @_;
219
220	my $grp = aio_group $cb;
221
222	add $grp aio_rename $src, $dst, sub {
223	if ($_[0] && $! == EXDEV) {
224	add $grp aio_open $src, O_RDONLY, 0, sub {
225	if (my $src_fh = $_[0]) {
226	my @stat = stat $src_fh;
227
228	add $grp aio_open $dst, O_WRONLY, 0200, sub {
229	if (my $dst_fh = $_[0]) {
230	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
231	close $src_fh;
232
233	if ($_[0] == $stat[7]) {
234	utime $stat[8], $stat[9], $dst;
235	chmod $stat[2] & 07777, $dst_fh;
236	chown $stat[4], $stat[5], $dst_fh;
237	close $dst_fh;
238
239	add $grp aio_unlink $src, sub {
240	$grp->result ($_[0]);
241	};
242	} else {
243	my $errno = $!;
244	add $grp aio_unlink $dst, sub {
245	$! = $errno;
246	$grp->result (-1);
247	};
248	}
249	};
250	} else {
251	$grp->result (-1);
252	}
253	},
254
255	} else {
256	$grp->result (-1);
257	}
258	};
259	} else {
260	$grp->result ($_[0]);
261	}
262	};
263
264	$grp
265	}
266		285
267	=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)
268		287
269	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
270	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
…		…
326	=item aio_unlink $pathname, $callback->($status)	345	=item aio_unlink $pathname, $callback->($status)
327		346
328	Asynchronously unlink (delete) a file and call the callback with the	347	Asynchronously unlink (delete) a file and call the callback with the
329	result code.	348	result code.
330		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
331	=item aio_link $srcpath, $dstpath, $callback->($status)	358	=item aio_link $srcpath, $dstpath, $callback->($status)
332		359
333	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
334	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.
335		362
…		…
355	sorted, and will B<NOT> include the C<.> and C<..> entries.	382	sorted, and will B<NOT> include the C<.> and C<..> entries.
356		383
357	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
358	with the filenames.	385	with the filenames.
359		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
360	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	489	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
361		490
362	[EXPERIMENTAL due to internal aio_group use]
363
364	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
365	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
366	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
367	recurse into (everything else).	494	recurse into (everything else, including symlinks to directories).
368		495
369	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_
370	C<$maxreq> specifies the maximum number of outstanding aio requests that	497	C<$maxreq> specifies the maximum number of outstanding aio requests that
371	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
372	will be chosen (currently 6).	499	will be chosen (currently 4).
373		500
374	On error, the callback is called without arguments, otherwise it receives	501	On error, the callback is called without arguments, otherwise it receives
375	two array-refs with path-relative entry names.	502	two array-refs with path-relative entry names.
376		503
377	Example:	504	Example:
…		…
414	=cut	541	=cut
415		542
416	sub aio_scandir($$$) {	543	sub aio_scandir($$$) {
417	my ($path, $maxreq, $cb) = @_;	544	my ($path, $maxreq, $cb) = @_;
418		545
		546	my $pri = aioreq_pri;
		547
419	my $grp = aio_group $cb;	548	my $grp = aio_group $cb;
420		549
421	$maxreq = 6 if $maxreq <= 0;	550	$maxreq = 4 if $maxreq <= 0;
422		551
423	# stat once	552	# stat once
		553	aioreq_pri $pri;
424	add $grp aio_stat $path, sub {	554	add $grp aio_stat $path, sub {
425	return $grp->result () if $_[0];	555	return $grp->result () if $_[0];
426	my $now = time;	556	my $now = time;
427	my $hash1 = join ":", (stat _)[0,1,3,7,9];	557	my $hash1 = join ":", (stat _)[0,1,3,7,9];
428		558
429	# read the directory entries	559	# read the directory entries
		560	aioreq_pri $pri;
430	add $grp aio_readdir $path, sub {	561	add $grp aio_readdir $path, sub {
431	my $entries = shift	562	my $entries = shift
432	or return $grp->result ();	563	or return $grp->result ();
433		564
434	# stat the dir another time	565	# stat the dir another time
		566	aioreq_pri $pri;
435	add $grp aio_stat $path, sub {	567	add $grp aio_stat $path, sub {
436	my $hash2 = join ":", (stat _)[0,1,3,7,9];	568	my $hash2 = join ":", (stat _)[0,1,3,7,9];
437		569
438	my $ndirs;	570	my $ndirs;
439		571
…		…
454	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],	586	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
455	@$entries];	587	@$entries];
456		588
457	my (@dirs, @nondirs);	589	my (@dirs, @nondirs);
458		590
459	my ($statcb, $schedcb);
460	my $nreq = 0;
461
462	my $statgrp = add $grp aio_group;	591	my $statgrp = add $grp aio_group sub {
		592	$grp->result (\@dirs, \@nondirs);
		593	};
463		594
464	$schedcb = sub {	595	limit $statgrp $maxreq;
465	if (@$entries) {	596	feed $statgrp sub {
466	if ($nreq < $maxreq) {	597	return unless @$entries;
467	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	}
468	$nreq++;	618	}
469	add $statgrp aio_stat "$path/$ent/.", sub { $statcb->($_[0], $ent) };
470	}	619	}
471	} elsif (!$nreq) {
472	# finished
473	$statgrp->cancel;
474	undef $statcb;
475	undef $schedcb;
476	$grp->result (\@dirs, \@nondirs);
477	}	620	};
478	};	621	};
479	$statcb = sub {
480	my ($status, $entry) = @_;
481
482	if ($status < 0) {
483	$nreq--;
484	push @nondirs, $entry;
485	&$schedcb;
486	} else {
487	# need to check for real directory
488	add $grp aio_lstat "$path/$entry", sub {
489	$nreq--;
490
491	if (-d _) {
492	push @dirs, $entry;
493
494	if (!--$ndirs) {
495	push @nondirs, @$entries;
496	$entries = [];
497	}
498	} else {
499	push @nondirs, $entry;
500	}
501
502	&$schedcb;
503	}
504	}
505	};
506
507	&$schedcb while @$entries && $nreq < $maxreq;
508	};	622	};
509	};	623	};
510	};	624	};
511		625
512	$grp	626	$grp
…		…
525	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
526	detected, it will be emulated by calling C<fsync> instead.	640	detected, it will be emulated by calling C<fsync> instead.
527		641
528	=item aio_group $callback->(...)	642	=item aio_group $callback->(...)
529		643
530	[EXPERIMENTAL]
531
532	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
533	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
534	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.
535		648
536	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
537	for more info.	650	for more info.
538		651
539	Example:	652	Example:
…		…
558	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
559	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
560	entered their execution phase. This can be used to measure request	673	entered their execution phase. This can be used to measure request
561	latency.	674	latency.
562		675
563	=item IO::AIO::aio_sleep $fractional_seconds, $callback->() NOT EXPORTED	676	=item IO::AIO::aio_busy $fractional_seconds, $callback->() NOT EXPORTED
564		677
565	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
566	the request workers to sleep for the given time.	679	the request workers to sleep for the given time.
567		680
568	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
569	like sleep and file handle readable/writable, the overhead this creates	682	like sleep and file handle readable/writable, the overhead this creates is
570	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
571	under artificial I/O pressure.	684	except to put your application under artificial I/O pressure.
572		685
573	=back	686	=back
574		687
575	=head2 IO::AIO::REQ CLASS	688	=head2 IO::AIO::REQ CLASS
576		689
577	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
578	called in non-void context.	691	called in non-void context.
579
580	A request always moves through the following five states in its lifetime,
581	in order: B<ready> (request has been created, but has not been executed
582	yet), B<execute> (request is currently being executed), B<pending>
583	(request has been executed but callback has not been called yet),
584	B<result> (results are being processed synchronously, includes calling the
585	callback) and B<done> (request has reached the end of its lifetime and
586	holds no resources anymore).
587		692
588	=over 4	693	=over 4
589		694
590	=item cancel $req	695	=item cancel $req
591		696
…		…
645	=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.
646		751
647	=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
648	any later time).	753	any later time).
649		754
650	=item * This does not harmonise well with C<max_outstanding>, so best do
651	not combine C<aio_group> with it. Groups and feeders are recommended for
652	this kind of concurrency-limiting.
653
654	=back	755	=back
655		756
656	Their lifetime, simplified, looks like this: when they are empty, they	757	Their lifetime, simplified, looks like this: when they are empty, they
657	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
658	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
…		…
673	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
674	dependencies.	775	dependencies.
675		776
676	Returns all its arguments.	777	Returns all its arguments.
677		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
678	=item $grp->result (...)	784	=item $grp->result (...)
679		785
680	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
681	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.
682		802
683	=item feed $grp $callback->($grp)	803	=item feed $grp $callback->($grp)
684
685	[VERY EXPERIMENTAL]
686		804
687	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
688	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,
689	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,
690	this might starve other requests for a potentially long time. For	808	this might starve other requests for a potentially long time. For
…		…
744		862
745	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
746	regularly. Returns the number of events processed. Returns immediately	864	regularly. Returns the number of events processed. Returns immediately
747	when no events are outstanding.	865	when no events are outstanding.
748		866
		867	If not all requests were processed for whatever reason, the filehandle
		868	will still be ready when C<poll_cb> returns.
		869
749	Example: Install an Event watcher that automatically calls	870	Example: Install an Event watcher that automatically calls
750	IO::AIO::poll_cb with high priority:	871	IO::AIO::poll_cb with high priority:
751		872
752	Event->io (fd => IO::AIO::poll_fileno,	873	Event->io (fd => IO::AIO::poll_fileno,
753	poll => 'r', async => 1,	874	poll => 'r', async => 1,
754	cb => \&IO::AIO::poll_cb);	875	cb => \&IO::AIO::poll_cb);
755		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
756	=item IO::AIO::poll_wait	893	=item IO::AIO::poll_wait
757		894
758	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
759	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
760	for some requests to finish).	897	for some requests to finish).
761		898
762	See C<nreqs> for an example.	899	See C<nreqs> for an example.
763		900
764	=item IO::AIO::nreqs	901	=item IO::AIO::nreqs
765		902
766	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
767	callback has not been invoked yet).	904	states (i.e. for which their callback has not been invoked yet).
768		905
769	Example: wait till there are no outstanding requests anymore:	906	Example: wait till there are no outstanding requests anymore:
770		907
771	IO::AIO::poll_wait, IO::AIO::poll_cb	908	IO::AIO::poll_wait, IO::AIO::poll_cb
772	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).
773		920
774	=item IO::AIO::flush	921	=item IO::AIO::flush
775		922
776	Wait till all outstanding AIO requests have been handled.	923	Wait till all outstanding AIO requests have been handled.
777		924
…		…
819	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
820	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.
821		968
822	Under normal circumstances you don't need to call this function.	969	Under normal circumstances you don't need to call this function.
823		970
824	=item $oldnreqs = IO::AIO::max_outstanding $nreqs	971	=item $oldmaxreqs = IO::AIO::max_outstanding $maxreqs
825		972
826	[DEPRECATED]	973	This is a very bad function to use in interactive programs because it
		974	blocks, and a bad way to reduce concurrency because it is inexact: Better
		975	use an C<aio_group> together with a feed callback.
827		976
828	Sets the maximum number of outstanding requests to C<$nreqs>. If you	977	Sets the maximum number of outstanding requests to C<$nreqs>. If you
829	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
830	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.
831		981
832	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
833	queue up many requests in a loop it often improves speed if you set	983	number of outstanding requests.
834	this to a relatively low number, such as C<100>.
835		984
836	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,
837	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
838	this function.	987	as a stop gap to shield against fatal memory overflow (with large values).
839
840	Under normal circumstances you don't need to call this function.
841		988
842	=back	989	=back
843		990
844	=cut	991	=cut
845		992
…		…
860	}	1007	}
861		1008
862	min_parallel 8;	1009	min_parallel 8;
863		1010
864	END {	1011	END {
865	max_parallel 0;	1012	min_parallel 1;
866	}	1013	flush;
		1014	};
867		1015
868	1;	1016	1;
869		1017
870	=head2 FORK BEHAVIOUR	1018	=head2 FORK BEHAVIOUR
871		1019
872	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:
873		1021
874	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
875	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
876	the fork the parent simply leaves the quiescent state and continues	1024	the fork the parent simply leaves the quiescent state and continues
877	request/result processing, while the child clears the request/result	1025	request/result processing, while the child frees the request/result queue
878	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
879	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
880	parent process has been reached again.	1028	parent process has been reached again.
881		1029
882	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
883	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
884	yet.	1032	yet.
885		1033
886	=head2 MEMORY USAGE	1034	=head2 MEMORY USAGE
887		1035
		1036	Per-request usage:
		1037
888	Each aio request uses - depending on your architecture - around 128 bytes	1038	Each aio request uses - depending on your architecture - around 100-200
889	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
890	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
891	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.
892		1043
893	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
894	problem.	1045	problem.
895		1046
896	Each thread needs a stack area which is usually around 16k, sometimes much	1047	Per-thread usage:
897	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.
898		1056
899	=head1 SEE ALSO	1057	=head1 SEE ALSO
900		1058
901	L<Coro::AIO>.	1059	L<Coro::AIO>.
902		1060

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Comparing IO-AIO/AIO.pm (file contents): Revision 1.68 by root, Tue Oct 24 03:17:39 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 1.68 by root, Tue Oct 24 03:17:39 2006 UTC vs.
Revision 1.85 by root, Sat Oct 28 01:40:30 2006 UTC