[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 1.82 by root, Fri Oct 27 20:10:06 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	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
57	and signal their completion. You don't need thread support in perl, and	57	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	58	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	59	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	60	functions available on many operating systems. However, they are often
61	(Linux doesn't allow them on normal files currently, for example),	61	not well-supported or restricted (Linux doesn't allow them on normal
62	and they would only support aio_read and aio_write, so the remaining	62	files currently, for example), and they would only support aio_read and
63	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.
64		65
65	Although the module will work with in the presence of other threads,	66	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	67	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	68	locking yourself, always call C<poll_cb> from within the same thread, or
68	call C<poll_cb> (or other 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).
69		120
70	=cut	121	=cut
71		122
72	package IO::AIO;	123	package IO::AIO;
73		124
…		…
80	our $VERSION = '2.0';	131	our $VERSION = '2.0';
81		132
82	our @AIO_REQ = 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
83	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
84	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
85	aio_group aio_nop);	136	aio_copy aio_group aio_nop aio_mknod);
86	our @EXPORT = (@AIO_REQ, qw(aioreq_pri));	137	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
87	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush	138	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
88	min_parallel max_parallel max_outstanding nreqs);	139	min_parallel max_parallel nreqs nready npending);
89		140
90	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';	141	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';
91		142
92	require XSLoader;	143	require XSLoader;
93	XSLoader::load ("IO::AIO", $VERSION);	144	XSLoader::load ("IO::AIO", $VERSION);
…		…
124	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)
125	use something else.	176	use something else.
126		177
127	=over 4	178	=over 4
128		179
129	=item aioreq_pri $pri	180	=item $prev_pri = aioreq_pri [$pri]
130		181
131	Sets the priority for the next aio request. The default priority	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
132	is C<0>, the minimum and maximum priorities are C<-4> and C<4>,	185	The default priority is C<0>, the minimum and maximum priorities are C<-4>
133	respectively. Requests with higher priority will be serviced first.	186	and C<4>, respectively. Requests with higher priority will be serviced
		187	first.
134		188
135	The priority will be reset to C<0> after each call to one of the C<aio_>	189	The priority will be reset to C<0> after each call to one of the C<aio_*>
136	functions.	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.
137		210
138	=item aio_open $pathname, $flags, $mode, $callback->($fh)	211	=item aio_open $pathname, $flags, $mode, $callback->($fh)
139		212
140	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
141	created filehandle for the file.	214	created filehandle for the file.
…		…
191		264
192	aio_read $fh, 7, 15, $buffer, 0, sub {	265	aio_read $fh, 7, 15, $buffer, 0, sub {
193	$_[0] > 0 or die "read error: $!";	266	$_[0] > 0 or die "read error: $!";
194	print "read $_[0] bytes: <$buffer>\n";	267	print "read $_[0] bytes: <$buffer>\n";
195	};	268	};
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		269
267	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)	270	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
268		271
269	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts	272	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
270	reading at byte offset C<$in_offset>, and starts writing at the current	273	reading at byte offset C<$in_offset>, and starts writing at the current
…		…
326	=item aio_unlink $pathname, $callback->($status)	329	=item aio_unlink $pathname, $callback->($status)
327		330
328	Asynchronously unlink (delete) a file and call the callback with the	331	Asynchronously unlink (delete) a file and call the callback with the
329	result code.	332	result code.
330		333
		334	=item aio_mknod $path, $mode, $dev, $callback->($status)
		335
		336	Asynchronously create a device node (or fifo). See mknod(2): the only
		337	portable value for C<$mode> is C<S_IFIFO> ored with permissions, and C<0>
		338	for C<$dev>.
		339
331	=item aio_link $srcpath, $dstpath, $callback->($status)	340	=item aio_link $srcpath, $dstpath, $callback->($status)
332		341
333	Asynchronously create a new link to the existing object at C<$srcpath> at	342	Asynchronously create a new link to the existing object at C<$srcpath> at
334	the path C<$dstpath> and call the callback with the result code.	343	the path C<$dstpath> and call the callback with the result code.
335		344
…		…
355	sorted, and will B<NOT> include the C<.> and C<..> entries.	364	sorted, and will B<NOT> include the C<.> and C<..> entries.
356		365
357	The callback a single argument which is either C<undef> or an array-ref	366	The callback a single argument which is either C<undef> or an array-ref
358	with the filenames.	367	with the filenames.
359		368
		369	=item aio_copy $srcpath, $dstpath, $callback->($status)
		370
		371	Try to copy the I<file> (directories not supported as either source or
		372	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		373	the C<0> (error) or C<-1> ok.
		374
		375	This is a composite request that it creates the destination file with
		376	mode 0200 and copies the contents of the source file into it using
		377	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
		378	uid/gid, in that order.
		379
		380	If an error occurs, the partial destination file will be unlinked, if
		381	possible, except when setting atime, mtime, access mode and uid/gid, where
		382	errors are being ignored.
		383
		384	=cut
		385
		386	sub aio_copy($$;$) {
		387	my ($src, $dst, $cb) = @_;
		388
		389	my $pri = aioreq_pri;
		390	my $grp = aio_group $cb;
		391
		392	aioreq_pri $pri;
		393	add $grp aio_open $src, O_RDONLY, 0, sub {
		394	if (my $src_fh = $_[0]) {
		395	my @stat = stat $src_fh;
		396
		397	aioreq_pri $pri;
		398	add $grp aio_open $dst, O_CREAT \| O_WRONLY \| O_TRUNC, 0200, sub {
		399	if (my $dst_fh = $_[0]) {
		400	aioreq_pri $pri;
		401	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
		402	if ($_[0] == $stat[7]) {
		403	$grp->result (0);
		404	close $src_fh;
		405
		406	# those should not normally block. should. should.
		407	utime $stat[8], $stat[9], $dst;
		408	chmod $stat[2] & 07777, $dst_fh;
		409	chown $stat[4], $stat[5], $dst_fh;
		410	close $dst_fh;
		411	} else {
		412	$grp->result (-1);
		413	close $src_fh;
		414	close $dst_fh;
		415
		416	aioreq $pri;
		417	add $grp aio_unlink $dst;
		418	}
		419	};
		420	} else {
		421	$grp->result (-1);
		422	}
		423	},
		424
		425	} else {
		426	$grp->result (-1);
		427	}
		428	};
		429
		430	$grp
		431	}
		432
		433	=item aio_move $srcpath, $dstpath, $callback->($status)
		434
		435	Try to move the I<file> (directories not supported as either source or
		436	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		437	the C<0> (error) or C<-1> ok.
		438
		439	This is a composite request that tries to rename(2) the file first. If
		440	rename files with C<EXDEV>, it copies the file with C<aio_copy> and, if
		441	that is successful, unlinking the C<$srcpath>.
		442
		443	=cut
		444
		445	sub aio_move($$;$) {
		446	my ($src, $dst, $cb) = @_;
		447
		448	my $pri = aioreq_pri;
		449	my $grp = aio_group $cb;
		450
		451	aioreq_pri $pri;
		452	add $grp aio_rename $src, $dst, sub {
		453	if ($_[0] && $! == EXDEV) {
		454	aioreq_pri $pri;
		455	add $grp aio_copy $src, $dst, sub {
		456	$grp->result ($_[0]);
		457
		458	if (!$_[0]) {
		459	aioreq_pri $pri;
		460	add $grp aio_unlink $src;
		461	}
		462	};
		463	} else {
		464	$grp->result ($_[0]);
		465	}
		466	};
		467
		468	$grp
		469	}
		470
360	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	471	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
361		472
362	[EXPERIMENTAL due to internal aio_group use]
363
364	Scans a directory (similar to C<aio_readdir>) but additionally tries to	473	Scans a directory (similar to C<aio_readdir>) but additionally tries to
365	separate the entries of directory C<$path> into two sets of names, ones	474	efficiently separate the entries of directory C<$path> into two sets of
366	you can recurse into (directories or links to them), and ones you cannot	475	names, directories you can recurse into (directories), and ones you cannot
367	recurse into (everything else).	476	recurse into (everything else, including symlinks to directories).
368		477
369	C<aio_scandir> is a composite request that creates of many sub requests_	478	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	479	C<$maxreq> specifies the maximum number of outstanding aio requests that
371	this function generates. If it is C<< <= 0 >>, then a suitable default	480	this function generates. If it is C<< <= 0 >>, then a suitable default
372	will be chosen (currently 6).	481	will be chosen (currently 4).
373		482
374	On error, the callback is called without arguments, otherwise it receives	483	On error, the callback is called without arguments, otherwise it receives
375	two array-refs with path-relative entry names.	484	two array-refs with path-relative entry names.
376		485
377	Example:	486	Example:
…		…
414	=cut	523	=cut
415		524
416	sub aio_scandir($$$) {	525	sub aio_scandir($$$) {
417	my ($path, $maxreq, $cb) = @_;	526	my ($path, $maxreq, $cb) = @_;
418		527
		528	my $pri = aioreq_pri;
		529
419	my $grp = aio_group $cb;	530	my $grp = aio_group $cb;
420		531
421	$maxreq = 6 if $maxreq <= 0;	532	$maxreq = 4 if $maxreq <= 0;
422		533
423	# stat once	534	# stat once
		535	aioreq_pri $pri;
424	add $grp aio_stat $path, sub {	536	add $grp aio_stat $path, sub {
425	return $grp->result () if $_[0];	537	return $grp->result () if $_[0];
426	my $now = time;	538	my $now = time;
427	my $hash1 = join ":", (stat _)[0,1,3,7,9];	539	my $hash1 = join ":", (stat _)[0,1,3,7,9];
428		540
429	# read the directory entries	541	# read the directory entries
		542	aioreq_pri $pri;
430	add $grp aio_readdir $path, sub {	543	add $grp aio_readdir $path, sub {
431	my $entries = shift	544	my $entries = shift
432	or return $grp->result ();	545	or return $grp->result ();
433		546
434	# stat the dir another time	547	# stat the dir another time
		548	aioreq_pri $pri;
435	add $grp aio_stat $path, sub {	549	add $grp aio_stat $path, sub {
436	my $hash2 = join ":", (stat _)[0,1,3,7,9];	550	my $hash2 = join ":", (stat _)[0,1,3,7,9];
437		551
438	my $ndirs;	552	my $ndirs;
439		553
…		…
454	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],	568	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
455	@$entries];	569	@$entries];
456		570
457	my (@dirs, @nondirs);	571	my (@dirs, @nondirs);
458		572
459	my ($statcb, $schedcb);
460	my $nreq = 0;
461
462	my $statgrp = add $grp aio_group;	573	my $statgrp = add $grp aio_group sub {
		574	$grp->result (\@dirs, \@nondirs);
		575	};
463		576
464	$schedcb = sub {	577	limit $statgrp $maxreq;
465	if (@$entries) {	578	feed $statgrp sub {
466	if ($nreq < $maxreq) {	579	return unless @$entries;
467	my $ent = pop @$entries;	580	my $entry = pop @$entries;
		581
		582	aioreq_pri $pri;
		583	add $statgrp aio_stat "$path/$entry/.", sub {
		584	if ($_[0] < 0) {
		585	push @nondirs, $entry;
		586	} else {
		587	# need to check for real directory
		588	aioreq_pri $pri;
		589	add $statgrp aio_lstat "$path/$entry", sub {
		590	if (-d _) {
		591	push @dirs, $entry;
		592
		593	unless (--$ndirs) {
		594	push @nondirs, @$entries;
		595	feed $statgrp;
		596	}
		597	} else {
		598	push @nondirs, $entry;
		599	}
468	$nreq++;	600	}
469	add $statgrp aio_stat "$path/$ent/.", sub { $statcb->($_[0], $ent) };
470	}	601	}
471	} elsif (!$nreq) {
472	# finished
473	$statgrp->cancel;
474	undef $statcb;
475	undef $schedcb;
476	$grp->result (\@dirs, \@nondirs);
477	}	602	};
478	};	603	};
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	};	604	};
509	};	605	};
510	};	606	};
511		607
512	$grp	608	$grp
…		…
525	If this call isn't available because your OS lacks it or it couldn't be	621	If this call isn't available because your OS lacks it or it couldn't be
526	detected, it will be emulated by calling C<fsync> instead.	622	detected, it will be emulated by calling C<fsync> instead.
527		623
528	=item aio_group $callback->(...)	624	=item aio_group $callback->(...)
529		625
530	[EXPERIMENTAL]
531
532	This is a very special aio request: Instead of doing something, it is a	626	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	627	container for other aio requests, which is useful if you want to bundle
534	many requests into a single, composite, request.	628	many requests into a single, composite, request with a definite callback
		629	and the ability to cancel the whole request with its subrequests.
535		630
536	Returns an object of class L<IO::AIO::GRP>. See its documentation below	631	Returns an object of class L<IO::AIO::GRP>. See its documentation below
537	for more info.	632	for more info.
538		633
539	Example:	634	Example:
…		…
558	phase and still requires a worker thread. Thus, the callback will not	653	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	654	be executed immediately but only after other requests in the queue have
560	entered their execution phase. This can be used to measure request	655	entered their execution phase. This can be used to measure request
561	latency.	656	latency.
562		657
563	=item IO::AIO::aio_sleep $fractional_seconds, $callback->() NOT EXPORTED	658	=item IO::AIO::aio_busy $fractional_seconds, $callback->() NOT EXPORTED
564		659
565	Mainly used for debugging and benchmarking, this aio request puts one of	660	Mainly used for debugging and benchmarking, this aio request puts one of
566	the request workers to sleep for the given time.	661	the request workers to sleep for the given time.
567		662
568	While it is theoretically handy to have simple I/O scheduling requests	663	While it is theoretically handy to have simple I/O scheduling requests
569	like sleep and file handle readable/writable, the overhead this creates	664	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	665	immense (it blocks a thread for a long time) so do not use this function
571	under artificial I/O pressure.	666	except to put your application under artificial I/O pressure.
572		667
573	=back	668	=back
574		669
575	=head2 IO::AIO::REQ CLASS	670	=head2 IO::AIO::REQ CLASS
576		671
577	All non-aggregate C<aio_*> functions return an object of this class when	672	All non-aggregate C<aio_*> functions return an object of this class when
578	called in non-void context.	673	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		674
588	=over 4	675	=over 4
589		676
590	=item cancel $req	677	=item cancel $req
591		678
…		…
645	=item * They can also can also be added to other IO::AIO::GRP objects.	732	=item * They can also can also be added to other IO::AIO::GRP objects.
646		733
647	=item * You must not add requests to a group from within the group callback (or	734	=item * You must not add requests to a group from within the group callback (or
648	any later time).	735	any later time).
649		736
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	737	=back
655		738
656	Their lifetime, simplified, looks like this: when they are empty, they	739	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	740	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	741	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	756	be added, including other groups, as long as you do not create circular
674	dependencies.	757	dependencies.
675		758
676	Returns all its arguments.	759	Returns all its arguments.
677		760
		761	=item $grp->cancel_subs
		762
		763	Cancel all subrequests and clears any feeder, but not the group request
		764	itself. Useful when you queued a lot of events but got a result early.
		765
678	=item $grp->result (...)	766	=item $grp->result (...)
679		767
680	Set the result value(s) that will be passed to the group callback when all	768	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.	769	subrequests have finished and set thre groups errno to the current value
		770	of errno (just like calling C<errno> without an error number). By default,
		771	no argument will be passed and errno is zero.
		772
		773	=item $grp->errno ([$errno])
		774
		775	Sets the group errno value to C<$errno>, or the current value of errno
		776	when the argument is missing.
		777
		778	Every aio request has an associated errno value that is restored when
		779	the callback is invoked. This method lets you change this value from its
		780	default (0).
		781
		782	Calling C<result> will also set errno, so make sure you either set C<$!>
		783	before the call to C<result>, or call c<errno> after it.
682		784
683	=item feed $grp $callback->($grp)	785	=item feed $grp $callback->($grp)
684
685	[VERY EXPERIMENTAL]
686		786
687	Sets a feeder/generator on this group: every group can have an attached	787	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,	788	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,	789	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	790	this might starve other requests for a potentially long time. For
…		…
744		844
745	Process all outstanding events on the result pipe. You have to call this	845	Process all outstanding events on the result pipe. You have to call this
746	regularly. Returns the number of events processed. Returns immediately	846	regularly. Returns the number of events processed. Returns immediately
747	when no events are outstanding.	847	when no events are outstanding.
748		848
		849	If not all requests were processed for whatever reason, the filehandle
		850	will still be ready when C<poll_cb> returns.
		851
749	Example: Install an Event watcher that automatically calls	852	Example: Install an Event watcher that automatically calls
750	IO::AIO::poll_cb with high priority:	853	IO::AIO::poll_cb with high priority:
751		854
752	Event->io (fd => IO::AIO::poll_fileno,	855	Event->io (fd => IO::AIO::poll_fileno,
753	poll => 'r', async => 1,	856	poll => 'r', async => 1,
754	cb => \&IO::AIO::poll_cb);	857	cb => \&IO::AIO::poll_cb);
755		858
		859	=item IO::AIO::poll_some $max_requests
		860
		861	Similar to C<poll_cb>, but only processes up to C<$max_requests> requests
		862	at a time.
		863
		864	Useful if you want to ensure some level of interactiveness when perl is
		865	not fast enough to process all requests in time.
		866
		867	Example: Install an Event watcher that automatically calls
		868	IO::AIO::poll_some with low priority, to ensure that other parts of the
		869	program get the CPU sometimes even under high AIO load.
		870
		871	Event->io (fd => IO::AIO::poll_fileno,
		872	poll => 'r', nice => 1,
		873	cb => sub { IO::AIO::poll_some 256 });
		874
756	=item IO::AIO::poll_wait	875	=item IO::AIO::poll_wait
757		876
758	Wait till the result filehandle becomes ready for reading (simply does a	877	Wait till the result filehandle becomes ready for reading (simply does a
759	C<select> on the filehandle. This is useful if you want to synchronously wait	878	C<select> on the filehandle. This is useful if you want to synchronously wait
760	for some requests to finish).	879	for some requests to finish).
761		880
762	See C<nreqs> for an example.	881	See C<nreqs> for an example.
763		882
764	=item IO::AIO::nreqs	883	=item IO::AIO::nreqs
765		884
766	Returns the number of requests currently outstanding (i.e. for which their	885	Returns the number of requests currently in the ready, execute or pending
767	callback has not been invoked yet).	886	states (i.e. for which their callback has not been invoked yet).
768		887
769	Example: wait till there are no outstanding requests anymore:	888	Example: wait till there are no outstanding requests anymore:
770		889
771	IO::AIO::poll_wait, IO::AIO::poll_cb	890	IO::AIO::poll_wait, IO::AIO::poll_cb
772	while IO::AIO::nreqs;	891	while IO::AIO::nreqs;
		892
		893	=item IO::AIO::nready
		894
		895	Returns the number of requests currently in the ready state (not yet
		896	executed).
		897
		898	=item IO::AIO::npending
		899
		900	Returns the number of requests currently in the pending state (executed,
		901	but not yet processed by poll_cb).
773		902
774	=item IO::AIO::flush	903	=item IO::AIO::flush
775		904
776	Wait till all outstanding AIO requests have been handled.	905	Wait till all outstanding AIO requests have been handled.
777		906
…		…
819	This module automatically runs C<max_parallel 0> at program end, to ensure	948	This module automatically runs C<max_parallel 0> at program end, to ensure
820	that all threads are killed and that there are no outstanding requests.	949	that all threads are killed and that there are no outstanding requests.
821		950
822	Under normal circumstances you don't need to call this function.	951	Under normal circumstances you don't need to call this function.
823		952
824	=item $oldnreqs = IO::AIO::max_outstanding $nreqs	953	=item $oldmaxreqs = IO::AIO::max_outstanding $maxreqs
825		954
826	[DEPRECATED]	955	This is a very bad function to use in interactive programs because it
		956	blocks, and a bad way to reduce concurrency because it is inexact: Better
		957	use an C<aio_group> together with a feed callback.
827		958
828	Sets the maximum number of outstanding requests to C<$nreqs>. If you	959	Sets the maximum number of outstanding requests to C<$nreqs>. If you
829	try to queue up more than this number of requests, the caller will block until	960	to queue up more than this number of requests, the next call to the
830	some requests have been handled.	961	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
		962	function will block until the limit is no longer exceeded.
831		963
832	The default is very large, so normally there is no practical limit. If you	964	The default value is very large, so there is no practical limit on the
833	queue up many requests in a loop it often improves speed if you set	965	number of outstanding requests.
834	this to a relatively low number, such as C<100>.
835		966
836	This function does not work well together with C<aio_group>'s, and their	967	You can still queue as many requests as you want. Therefore,
837	feeder interface is better suited to limiting concurrency, so do not use	968	C<max_oustsanding> is mainly useful in simple scripts (with low values) or
838	this function.	969	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		970
842	=back	971	=back
843		972
844	=cut	973	=cut
845		974
…		…
860	}	989	}
861		990
862	min_parallel 8;	991	min_parallel 8;
863		992
864	END {	993	END {
865	max_parallel 0;	994	flush;
866	}	995	};
867		996
868	1;	997	1;
869		998
870	=head2 FORK BEHAVIOUR	999	=head2 FORK BEHAVIOUR
871		1000
872	This module should do "the right thing" when the process using it forks:	1001	This module should do "the right thing" when the process using it forks:
873		1002
874	Before the fork, IO::AIO enters a quiescent state where no requests	1003	Before the fork, IO::AIO enters a quiescent state where no requests
875	can be added in other threads and no results will be processed. After	1004	can be added in other threads and no results will be processed. After
876	the fork the parent simply leaves the quiescent state and continues	1005	the fork the parent simply leaves the quiescent state and continues
877	request/result processing, while the child clears the request/result	1006	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	1007	(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	1008	parent). Threads will be started on demand until the limit set in the
880	parent process has been reached again.	1009	parent process has been reached again.
881		1010
882	In short: the parent will, after a short pause, continue as if fork had	1011	In short: the parent will, after a short pause, continue as if fork had
883	not been called, while the child will act as if IO::AIO has not been used	1012	not been called, while the child will act as if IO::AIO has not been used
884	yet.	1013	yet.
885		1014
886	=head2 MEMORY USAGE	1015	=head2 MEMORY USAGE
887		1016
		1017	Per-request usage:
		1018
888	Each aio request uses - depending on your architecture - around 128 bytes	1019	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	1020	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	1021	a few hundred bytes), readdir requires a result buffer and so on. Perl
891	also be locked.	1022	scalars and other data passed into aio requests will also be locked and
		1023	will consume memory till the request has entered the done state.
892		1024
893	This is now awfully much, so queuing lots of requests is not usually a	1025	This is now awfully much, so queuing lots of requests is not usually a
894	problem.	1026	problem.
895		1027
896	Each thread needs a stack area which is usually around 16k, sometimes much	1028	Per-thread usage:
897	larger, depending on the OS.	1029
		1030	In the execution phase, some aio requests require more memory for
		1031	temporary buffers, and each thread requires a stack and other data
		1032	structures (usually around 16k-128k, depending on the OS).
		1033
		1034	=head1 KNOWN BUGS
		1035
		1036	Known bugs will be fixed in the next release.
898		1037
899	=head1 SEE ALSO	1038	=head1 SEE ALSO
900		1039
901	L<Coro::AIO>.	1040	L<Coro::AIO>.
902		1041

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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 1.82 by root, Fri Oct 27 20:10:06 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 1.82 by root, Fri Oct 27 20:10:06 2006 UTC