[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 1.80 by root, Thu Oct 26 16:28:33 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
…		…
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_group aio_nop);
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.
…		…
194	print "read $_[0] bytes: <$buffer>\n";	267	print "read $_[0] bytes: <$buffer>\n";
195	};	268	};
196		269
197	=item aio_move $srcpath, $dstpath, $callback->($status)	270	=item aio_move $srcpath, $dstpath, $callback->($status)
198		271
199	[EXPERIMENTAL due to internal aio_group use]
200
201	Try to move the I<file> (directories not supported as either source or	272	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	273	destination) from C<$srcpath> to C<$dstpath> and call the callback with
203	the C<0> (error) or C<-1> ok.	274	the C<0> (error) or C<-1> ok.
204		275
205	This is a composite request that tries to rename(2) the file first. If	276	This is a composite request that tries to rename(2) the file first. If
…		…
215	=cut	286	=cut
216		287
217	sub aio_move($$$) {	288	sub aio_move($$$) {
218	my ($src, $dst, $cb) = @_;	289	my ($src, $dst, $cb) = @_;
219		290
		291	my $pri = aioreq_pri;
220	my $grp = aio_group $cb;	292	my $grp = aio_group $cb;
221		293
		294	aioreq_pri $pri;
222	add $grp aio_rename $src, $dst, sub {	295	add $grp aio_rename $src, $dst, sub {
223	if ($_[0] && $! == EXDEV) {	296	if ($_[0] && $! == EXDEV) {
		297	aioreq_pri $pri;
224	add $grp aio_open $src, O_RDONLY, 0, sub {	298	add $grp aio_open $src, O_RDONLY, 0, sub {
225	if (my $src_fh = $_[0]) {	299	if (my $src_fh = $_[0]) {
226	my @stat = stat $src_fh;	300	my @stat = stat $src_fh;
227		301
		302	aioreq_pri $pri;
228	add $grp aio_open $dst, O_WRONLY, 0200, sub {	303	add $grp aio_open $dst, O_WRONLY, 0200, sub {
229	if (my $dst_fh = $_[0]) {	304	if (my $dst_fh = $_[0]) {
		305	aioreq_pri $pri;
230	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {	306	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
231	close $src_fh;	307	close $src_fh;
232		308
233	if ($_[0] == $stat[7]) {	309	if ($_[0] == $stat[7]) {
234	utime $stat[8], $stat[9], $dst;	310	utime $stat[8], $stat[9], $dst;
235	chmod $stat[2] & 07777, $dst_fh;	311	chmod $stat[2] & 07777, $dst_fh;
236	chown $stat[4], $stat[5], $dst_fh;	312	chown $stat[4], $stat[5], $dst_fh;
237	close $dst_fh;	313	close $dst_fh;
238		314
		315	aioreq_pri $pri;
239	add $grp aio_unlink $src, sub {	316	add $grp aio_unlink $src, sub {
240	$grp->result ($_[0]);	317	$grp->result ($_[0]);
241	};	318	};
242	} else {	319	} else {
243	my $errno = $!;	320	my $errno = $!;
		321	aioreq_pri $pri;
244	add $grp aio_unlink $dst, sub {	322	add $grp aio_unlink $dst, sub {
245	$! = $errno;	323	$! = $errno;
246	$grp->result (-1);	324	$grp->result (-1);
247	};	325	};
248	}	326	}
…		…
357	The callback a single argument which is either C<undef> or an array-ref	435	The callback a single argument which is either C<undef> or an array-ref
358	with the filenames.	436	with the filenames.
359		437
360	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	438	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
361		439
362	[EXPERIMENTAL due to internal aio_group use]
363
364	Scans a directory (similar to C<aio_readdir>) but additionally tries to	440	Scans a directory (similar to C<aio_readdir>) but additionally tries to
365	separate the entries of directory C<$path> into two sets of names, ones	441	efficiently separate the entries of directory C<$path> into two sets of
366	you can recurse into (directories or links to them), and ones you cannot	442	names, directories you can recurse into (directories), and ones you cannot
367	recurse into (everything else).	443	recurse into (everything else, including symlinks to directories).
368		444
369	C<aio_scandir> is a composite request that creates of many sub requests_	445	C<aio_scandir> is a composite request that creates of many sub requests_
370	C<$maxreq> specifies the maximum number of outstanding aio requests that	446	C<$maxreq> specifies the maximum number of outstanding aio requests that
371	this function generates. If it is C<< <= 0 >>, then a suitable default	447	this function generates. If it is C<< <= 0 >>, then a suitable default
372	will be chosen (currently 6).	448	will be chosen (currently 6).
…		…
414	=cut	490	=cut
415		491
416	sub aio_scandir($$$) {	492	sub aio_scandir($$$) {
417	my ($path, $maxreq, $cb) = @_;	493	my ($path, $maxreq, $cb) = @_;
418		494
		495	my $pri = aioreq_pri;
		496
419	my $grp = aio_group $cb;	497	my $grp = aio_group $cb;
420		498
421	$maxreq = 6 if $maxreq <= 0;	499	$maxreq = 6 if $maxreq <= 0;
422		500
423	# stat once	501	# stat once
		502	aioreq_pri $pri;
424	add $grp aio_stat $path, sub {	503	add $grp aio_stat $path, sub {
425	return $grp->result () if $_[0];	504	return $grp->result () if $_[0];
426	my $now = time;	505	my $now = time;
427	my $hash1 = join ":", (stat _)[0,1,3,7,9];	506	my $hash1 = join ":", (stat _)[0,1,3,7,9];
428		507
429	# read the directory entries	508	# read the directory entries
		509	aioreq_pri $pri;
430	add $grp aio_readdir $path, sub {	510	add $grp aio_readdir $path, sub {
431	my $entries = shift	511	my $entries = shift
432	or return $grp->result ();	512	or return $grp->result ();
433		513
434	# stat the dir another time	514	# stat the dir another time
		515	aioreq_pri $pri;
435	add $grp aio_stat $path, sub {	516	add $grp aio_stat $path, sub {
436	my $hash2 = join ":", (stat _)[0,1,3,7,9];	517	my $hash2 = join ":", (stat _)[0,1,3,7,9];
437		518
438	my $ndirs;	519	my $ndirs;
439		520
…		…
454	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],	535	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
455	@$entries];	536	@$entries];
456		537
457	my (@dirs, @nondirs);	538	my (@dirs, @nondirs);
458		539
459	my ($statcb, $schedcb);
460	my $nreq = 0;
461
462	my $statgrp = add $grp aio_group;	540	my $statgrp = add $grp aio_group sub {
		541	$grp->result (\@dirs, \@nondirs);
		542	};
463		543
464	$schedcb = sub {	544	limit $statgrp $maxreq;
465	if (@$entries) {	545	feed $statgrp sub {
466	if ($nreq < $maxreq) {	546	return unless @$entries;
467	my $ent = pop @$entries;	547	my $entry = pop @$entries;
		548
		549	aioreq_pri $pri;
		550	add $statgrp aio_stat "$path/$entry/.", sub {
		551	if ($_[0] < 0) {
		552	push @nondirs, $entry;
		553	} else {
		554	# need to check for real directory
		555	aioreq_pri $pri;
		556	add $statgrp aio_lstat "$path/$entry", sub {
		557	if (-d _) {
		558	push @dirs, $entry;
		559
		560	unless (--$ndirs) {
		561	push @nondirs, @$entries;
		562	feed $statgrp;
		563	}
		564	} else {
		565	push @nondirs, $entry;
		566	}
468	$nreq++;	567	}
469	add $statgrp aio_stat "$path/$ent/.", sub { $statcb->($_[0], $ent) };
470	}	568	}
471	} elsif (!$nreq) {
472	# finished
473	$statgrp->cancel;
474	undef $statcb;
475	undef $schedcb;
476	$grp->result (\@dirs, \@nondirs);
477	}	569	};
478	};	570	};
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	};	571	};
509	};	572	};
510	};	573	};
511		574
512	$grp	575	$grp
…		…
525	If this call isn't available because your OS lacks it or it couldn't be	588	If this call isn't available because your OS lacks it or it couldn't be
526	detected, it will be emulated by calling C<fsync> instead.	589	detected, it will be emulated by calling C<fsync> instead.
527		590
528	=item aio_group $callback->(...)	591	=item aio_group $callback->(...)
529		592
530	[EXPERIMENTAL]
531
532	This is a very special aio request: Instead of doing something, it is a	593	This is a very special aio request: Instead of doing something, it is a
533	container for other aio requests, which is useful if you want to bundle	594	container for other aio requests, which is useful if you want to bundle
534	many requests into a single, composite, request.	595	many requests into a single, composite, request with a definite callback
		596	and the ability to cancel the whole request with its subrequests.
535		597
536	Returns an object of class L<IO::AIO::GRP>. See its documentation below	598	Returns an object of class L<IO::AIO::GRP>. See its documentation below
537	for more info.	599	for more info.
538		600
539	Example:	601	Example:
…		…
558	phase and still requires a worker thread. Thus, the callback will not	620	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	621	be executed immediately but only after other requests in the queue have
560	entered their execution phase. This can be used to measure request	622	entered their execution phase. This can be used to measure request
561	latency.	623	latency.
562		624
563	=item IO::AIO::aio_sleep $fractional_seconds, $callback->() NOT EXPORTED	625	=item IO::AIO::aio_busy $fractional_seconds, $callback->() NOT EXPORTED
564		626
565	Mainly used for debugging and benchmarking, this aio request puts one of	627	Mainly used for debugging and benchmarking, this aio request puts one of
566	the request workers to sleep for the given time.	628	the request workers to sleep for the given time.
567		629
568	While it is theoretically handy to have simple I/O scheduling requests	630	While it is theoretically handy to have simple I/O scheduling requests
569	like sleep and file handle readable/writable, the overhead this creates	631	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	632	immense (it blocks a thread for a long time) so do not use this function
571	under artificial I/O pressure.	633	except to put your application under artificial I/O pressure.
572		634
573	=back	635	=back
574		636
575	=head2 IO::AIO::REQ CLASS	637	=head2 IO::AIO::REQ CLASS
576		638
577	All non-aggregate C<aio_*> functions return an object of this class when	639	All non-aggregate C<aio_*> functions return an object of this class when
578	called in non-void context.	640	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		641
588	=over 4	642	=over 4
589		643
590	=item cancel $req	644	=item cancel $req
591		645
…		…
645	=item * They can also can also be added to other IO::AIO::GRP objects.	699	=item * They can also can also be added to other IO::AIO::GRP objects.
646		700
647	=item * You must not add requests to a group from within the group callback (or	701	=item * You must not add requests to a group from within the group callback (or
648	any later time).	702	any later time).
649		703
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	704	=back
655		705
656	Their lifetime, simplified, looks like this: when they are empty, they	706	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	707	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	708	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	723	be added, including other groups, as long as you do not create circular
674	dependencies.	724	dependencies.
675		725
676	Returns all its arguments.	726	Returns all its arguments.
677		727
		728	=item $grp->cancel_subs
		729
		730	Cancel all subrequests and clears any feeder, but not the group request
		731	itself. Useful when you queued a lot of events but got a result early.
		732
678	=item $grp->result (...)	733	=item $grp->result (...)
679		734
680	Set the result value(s) that will be passed to the group callback when all	735	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.	736	subrequests have finished and set thre groups errno to the current value
		737	of errno (just like calling C<errno> without an error number). By default,
		738	no argument will be passed and errno is zero.
		739
		740	=item $grp->errno ([$errno])
		741
		742	Sets the group errno value to C<$errno>, or the current value of errno
		743	when the argument is missing.
		744
		745	Every aio request has an associated errno value that is restored when
		746	the callback is invoked. This method lets you change this value from its
		747	default (0).
		748
		749	Calling C<result> will also set errno, so make sure you either set C<$!>
		750	before the call to C<result>, or call c<errno> after it.
682		751
683	=item feed $grp $callback->($grp)	752	=item feed $grp $callback->($grp)
684
685	[VERY EXPERIMENTAL]
686		753
687	Sets a feeder/generator on this group: every group can have an attached	754	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,	755	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,	756	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	757	this might starve other requests for a potentially long time. For
…		…
744		811
745	Process all outstanding events on the result pipe. You have to call this	812	Process all outstanding events on the result pipe. You have to call this
746	regularly. Returns the number of events processed. Returns immediately	813	regularly. Returns the number of events processed. Returns immediately
747	when no events are outstanding.	814	when no events are outstanding.
748		815
		816	If not all requests were processed for whatever reason, the filehandle
		817	will still be ready when C<poll_cb> returns.
		818
749	Example: Install an Event watcher that automatically calls	819	Example: Install an Event watcher that automatically calls
750	IO::AIO::poll_cb with high priority:	820	IO::AIO::poll_cb with high priority:
751		821
752	Event->io (fd => IO::AIO::poll_fileno,	822	Event->io (fd => IO::AIO::poll_fileno,
753	poll => 'r', async => 1,	823	poll => 'r', async => 1,
754	cb => \&IO::AIO::poll_cb);	824	cb => \&IO::AIO::poll_cb);
755		825
		826	=item IO::AIO::poll_some $max_requests
		827
		828	Similar to C<poll_cb>, but only processes up to C<$max_requests> requests
		829	at a time.
		830
		831	Useful if you want to ensure some level of interactiveness when perl is
		832	not fast enough to process all requests in time.
		833
		834	Example: Install an Event watcher that automatically calls
		835	IO::AIO::poll_some with low priority, to ensure that other parts of the
		836	program get the CPU sometimes even under high AIO load.
		837
		838	Event->io (fd => IO::AIO::poll_fileno,
		839	poll => 'r', nice => 1,
		840	cb => sub { IO::AIO::poll_some 256 });
		841
756	=item IO::AIO::poll_wait	842	=item IO::AIO::poll_wait
757		843
758	Wait till the result filehandle becomes ready for reading (simply does a	844	Wait till the result filehandle becomes ready for reading (simply does a
759	C<select> on the filehandle. This is useful if you want to synchronously wait	845	C<select> on the filehandle. This is useful if you want to synchronously wait
760	for some requests to finish).	846	for some requests to finish).
761		847
762	See C<nreqs> for an example.	848	See C<nreqs> for an example.
763		849
764	=item IO::AIO::nreqs	850	=item IO::AIO::nreqs
765		851
766	Returns the number of requests currently outstanding (i.e. for which their	852	Returns the number of requests currently in the ready, execute or pending
767	callback has not been invoked yet).	853	states (i.e. for which their callback has not been invoked yet).
768		854
769	Example: wait till there are no outstanding requests anymore:	855	Example: wait till there are no outstanding requests anymore:
770		856
771	IO::AIO::poll_wait, IO::AIO::poll_cb	857	IO::AIO::poll_wait, IO::AIO::poll_cb
772	while IO::AIO::nreqs;	858	while IO::AIO::nreqs;
		859
		860	=item IO::AIO::nready
		861
		862	Returns the number of requests currently in the ready state (not yet
		863	executed).
		864
		865	=item IO::AIO::npending
		866
		867	Returns the number of requests currently in the pending state (executed,
		868	but not yet processed by poll_cb).
773		869
774	=item IO::AIO::flush	870	=item IO::AIO::flush
775		871
776	Wait till all outstanding AIO requests have been handled.	872	Wait till all outstanding AIO requests have been handled.
777		873
…		…
819	This module automatically runs C<max_parallel 0> at program end, to ensure	915	This module automatically runs C<max_parallel 0> at program end, to ensure
820	that all threads are killed and that there are no outstanding requests.	916	that all threads are killed and that there are no outstanding requests.
821		917
822	Under normal circumstances you don't need to call this function.	918	Under normal circumstances you don't need to call this function.
823		919
824	=item $oldnreqs = IO::AIO::max_outstanding $nreqs	920	=item $oldmaxreqs = IO::AIO::max_outstanding $maxreqs
825		921
826	[DEPRECATED]	922	This is a very bad function to use in interactive programs because it
		923	blocks, and a bad way to reduce concurrency because it is inexact: Better
		924	use an C<aio_group> together with a feed callback.
827		925
828	Sets the maximum number of outstanding requests to C<$nreqs>. If you	926	Sets the maximum number of outstanding requests to C<$nreqs>. If you
829	try to queue up more than this number of requests, the caller will block until	927	to queue up more than this number of requests, the next call to the
830	some requests have been handled.	928	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
		929	function will block until the limit is no longer exceeded.
831		930
832	The default is very large, so normally there is no practical limit. If you	931	The default value is very large, so there is no practical limit on the
833	queue up many requests in a loop it often improves speed if you set	932	number of outstanding requests.
834	this to a relatively low number, such as C<100>.
835		933
836	This function does not work well together with C<aio_group>'s, and their	934	You can still queue as many requests as you want. Therefore,
837	feeder interface is better suited to limiting concurrency, so do not use	935	C<max_oustsanding> is mainly useful in simple scripts (with low values) or
838	this function.	936	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		937
842	=back	938	=back
843		939
844	=cut	940	=cut
845		941
…		…
872	This module should do "the right thing" when the process using it forks:	968	This module should do "the right thing" when the process using it forks:
873		969
874	Before the fork, IO::AIO enters a quiescent state where no requests	970	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	971	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	972	the fork the parent simply leaves the quiescent state and continues
877	request/result processing, while the child clears the request/result	973	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	974	(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	975	parent). Threads will be started on demand until the limit set in the
880	parent process has been reached again.	976	parent process has been reached again.
881		977
882	In short: the parent will, after a short pause, continue as if fork had	978	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	979	not been called, while the child will act as if IO::AIO has not been used
884	yet.	980	yet.
885		981
886	=head2 MEMORY USAGE	982	=head2 MEMORY USAGE
887		983
		984	Per-request usage:
		985
888	Each aio request uses - depending on your architecture - around 128 bytes	986	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	987	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	988	a few hundred bytes), readdir requires a result buffer and so on. Perl
891	also be locked.	989	scalars and other data passed into aio requests will also be locked and
		990	will consume memory till the request has entered the done state.
892		991
893	This is now awfully much, so queuing lots of requests is not usually a	992	This is now awfully much, so queuing lots of requests is not usually a
894	problem.	993	problem.
895		994
896	Each thread needs a stack area which is usually around 16k, sometimes much	995	Per-thread usage:
897	larger, depending on the OS.	996
		997	In the execution phase, some aio requests require more memory for
		998	temporary buffers, and each thread requires a stack and other data
		999	structures (usually around 16k-128k, depending on the OS).
		1000
		1001	=head1 KNOWN BUGS
		1002
		1003	Known bugs will be fixed in the next release.
898		1004
899	=head1 SEE ALSO	1005	=head1 SEE ALSO
900		1006
901	L<Coro::AIO>.	1007	L<Coro::AIO>.
902		1008

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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 1.80 by root, Thu Oct 26 16:28:33 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 1.80 by root, Thu Oct 26 16:28:33 2006 UTC