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

Comparing IO-AIO/AIO.pm (file contents):
Revision 1.61 by root, Sun Oct 22 13:52:11 2006 UTC vs.
Revision 1.78 by root, Thu Oct 26 12:38:04 2006 UTC

…		…
18	};	18	};
19		19
20	# version 2+ has request and group objects	20	# version 2+ has request and group objects
21	use IO::AIO 2;	21	use IO::AIO 2;
22		22
		23	aioreq_pri 4; # give next request a very high priority
23	my $req = aio_unlink "/tmp/file", sub { };	24	my $req = aio_unlink "/tmp/file", sub { };
24	$req->cancel; # cancel request if still in queue	25	$req->cancel; # cancel request if still in queue
25		26
26	my $grp = aio_group sub { print "all stats done\n" };	27	my $grp = aio_group sub { print "all stats done\n" };
27	add $grp aio_stat "..." for ...;	28	add $grp aio_stat "..." for ...;
…		…
50	=head1 DESCRIPTION	51	=head1 DESCRIPTION
51		52
52	This module implements asynchronous I/O using whatever means your	53	This module implements asynchronous I/O using whatever means your
53	operating system supports.	54	operating system supports.
54		55
55	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
56	and signal their completion. You don't need thread support in your libc or	57	requests and signal their completion. You don't need thread support
57	perl, and the threads created by this module will not be visible to the	58	in perl, and the threads created by this module will not be visible
58	pthreads library. In the future, this module might make use of the native	59	to perl. In the future, this module might make use of the native aio
59	aio functions available on many operating systems. However, they are often	60	functions available on many operating systems. However, they are often
60	not well-supported (Linux doesn't allow them on normal files currently,	61	not well-supported or restricted (Linux doesn't allow them on normal
61	for example), and they would only support aio_read and aio_write, so the	62	files currently, for example), and they would only support aio_read and
62	remaining functionality would have to be implemented using threads anyway.	63	aio_write, so the remaining functionality would have to be implemented
		64	using threads anyway.
63		65
64	Although the module will work with in the presence of other threads, it is	66	Although the module will work with in the presence of other (Perl-)
65	currently not reentrant, so use appropriate locking yourself, always call	67	threads, it is currently not reentrant in any way, so use appropriate
66	C<poll_cb> from within the same thread, or never call C<poll_cb> (or other	68	locking yourself, always call C<poll_cb> from within the same thread, or
67	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).
68		120
69	=cut	121	=cut
70		122
71	package IO::AIO;	123	package IO::AIO;
72		124
…		…
76	use base 'Exporter';	128	use base 'Exporter';
77		129
78	BEGIN {	130	BEGIN {
79	our $VERSION = '2.0';	131	our $VERSION = '2.0';
80		132
81	our @EXPORT = qw(aio_sendfile aio_read aio_write aio_open aio_close aio_stat	133	our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close aio_stat
82	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
83	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
84	aio_group);	136	aio_group aio_nop);
85	our @EXPORT_OK = qw(poll_fileno poll_cb min_parallel max_parallel max_outstanding nreqs);	137	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
		138	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
		139	min_parallel max_parallel nreqs);
86		140
87	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';	141	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';
88		142
89	require XSLoader;	143	require XSLoader;
90	XSLoader::load ("IO::AIO", $VERSION);	144	XSLoader::load ("IO::AIO", $VERSION);
…		…
121	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)
122	use something else.	176	use something else.
123		177
124	=over 4	178	=over 4
125		179
		180	=item aioreq_pri $pri
		181
		182	Sets the priority for the next aio request. The default priority
		183	is C<0>, the minimum and maximum priorities are C<-4> and C<4>,
		184	respectively. Requests with higher priority will be serviced first.
		185
		186	The priority will be reset to C<0> after each call to one of the C<aio_>
		187	functions.
		188
		189	Example: open a file with low priority, then read something from it with
		190	higher priority so the read request is serviced before other low priority
		191	open requests (potentially spamming the cache):
		192
		193	aioreq_pri -3;
		194	aio_open ..., sub {
		195	return unless $_[0];
		196
		197	aioreq_pri -2;
		198	aio_read $_[0], ..., sub {
		199	...
		200	};
		201	};
		202
		203	=item aioreq_nice $pri_adjust
		204
		205	Similar to C<aioreq_pri>, but subtracts the given value from the current
		206	priority, so effects are cumulative.
		207
126	=item aio_open $pathname, $flags, $mode, $callback->($fh)	208	=item aio_open $pathname, $flags, $mode, $callback->($fh)
127		209
128	Asynchronously open or create a file and call the callback with a newly	210	Asynchronously open or create a file and call the callback with a newly
129	created filehandle for the file.	211	created filehandle for the file.
130		212
…		…
181	$_[0] > 0 or die "read error: $!";	263	$_[0] > 0 or die "read error: $!";
182	print "read $_[0] bytes: <$buffer>\n";	264	print "read $_[0] bytes: <$buffer>\n";
183	};	265	};
184		266
185	=item aio_move $srcpath, $dstpath, $callback->($status)	267	=item aio_move $srcpath, $dstpath, $callback->($status)
186
187	[EXPERIMENTAL due to internal aio_group use]
188		268
189	Try to move the I<file> (directories not supported as either source or	269	Try to move the I<file> (directories not supported as either source or
190	destination) from C<$srcpath> to C<$dstpath> and call the callback with	270	destination) from C<$srcpath> to C<$dstpath> and call the callback with
191	the C<0> (error) or C<-1> ok.	271	the C<0> (error) or C<-1> ok.
192		272
…		…
345	The callback a single argument which is either C<undef> or an array-ref	425	The callback a single argument which is either C<undef> or an array-ref
346	with the filenames.	426	with the filenames.
347		427
348	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	428	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
349		429
350	[EXPERIMENTAL due to internal aio_group use]
351
352	Scans a directory (similar to C<aio_readdir>) but additionally tries to	430	Scans a directory (similar to C<aio_readdir>) but additionally tries to
353	separate the entries of directory C<$path> into two sets of names, ones	431	efficiently separate the entries of directory C<$path> into two sets of
354	you can recurse into (directories or links to them), and ones you cannot	432	names, directories you can recurse into (directories), and ones you cannot
355	recurse into (everything else).	433	recurse into (everything else, including symlinks to directories).
356		434
357	C<aio_scandir> is a composite request that creates of many sub requests_	435	C<aio_scandir> is a composite request that creates of many sub requests_
358	C<$maxreq> specifies the maximum number of outstanding aio requests that	436	C<$maxreq> specifies the maximum number of outstanding aio requests that
359	this function generates. If it is C<< <= 0 >>, then a suitable default	437	this function generates. If it is C<< <= 0 >>, then a suitable default
360	will be chosen (currently 6).	438	will be chosen (currently 6).
…		…
442	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],	520	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
443	@$entries];	521	@$entries];
444		522
445	my (@dirs, @nondirs);	523	my (@dirs, @nondirs);
446		524
447	my ($statcb, $schedcb);
448	my $nreq = 0;
449
450	my $statgrp = add $grp aio_group;	525	my $statgrp = add $grp aio_group sub {
		526	$grp->result (\@dirs, \@nondirs);
		527	};
451		528
452	$schedcb = sub {	529	limit $statgrp $maxreq;
453	if (@$entries) {	530	feed $statgrp sub {
454	if ($nreq < $maxreq) {	531	return unless @$entries;
455	my $ent = pop @$entries;	532	my $entry = pop @$entries;
		533
		534	add $statgrp aio_stat "$path/$entry/.", sub {
		535	if ($_[0] < 0) {
		536	push @nondirs, $entry;
		537	} else {
		538	# need to check for real directory
		539	add $statgrp aio_lstat "$path/$entry", sub {
		540	if (-d _) {
		541	push @dirs, $entry;
		542
		543	unless (--$ndirs) {
		544	push @nondirs, @$entries;
		545	feed $statgrp;
		546	}
		547	} else {
		548	push @nondirs, $entry;
		549	}
456	$nreq++;	550	}
457	add $statgrp aio_stat "$path/$ent/.", sub { $statcb->($_[0], $ent) };
458	}	551	}
459	} elsif (!$nreq) {
460	# finished
461	$statgrp->cancel;
462	undef $statcb;
463	undef $schedcb;
464	$grp->result (\@dirs, \@nondirs);
465	}	552	};
466	};	553	};
467	$statcb = sub {
468	my ($status, $entry) = @_;
469
470	if ($status < 0) {
471	$nreq--;
472	push @nondirs, $entry;
473	&$schedcb;
474	} else {
475	# need to check for real directory
476	add $grp aio_lstat "$path/$entry", sub {
477	$nreq--;
478
479	if (-d _) {
480	push @dirs, $entry;
481
482	if (!--$ndirs) {
483	push @nondirs, @$entries;
484	$entries = [];
485	}
486	} else {
487	push @nondirs, $entry;
488	}
489
490	&$schedcb;
491	}
492	}
493	};
494
495	&$schedcb while @$entries && $nreq < $maxreq;
496	};	554	};
497	};	555	};
498	};	556	};
499		557
500	$grp	558	$grp
…		…
513	If this call isn't available because your OS lacks it or it couldn't be	571	If this call isn't available because your OS lacks it or it couldn't be
514	detected, it will be emulated by calling C<fsync> instead.	572	detected, it will be emulated by calling C<fsync> instead.
515		573
516	=item aio_group $callback->(...)	574	=item aio_group $callback->(...)
517		575
518	[EXPERIMENTAL]
519
520	This is a very special aio request: Instead of doing something, it is a	576	This is a very special aio request: Instead of doing something, it is a
521	container for other aio requests, which is useful if you want to bundle	577	container for other aio requests, which is useful if you want to bundle
522	many requests into a single, composite, request.	578	many requests into a single, composite, request with a definite callback
		579	and the ability to cancel the whole request with its subrequests.
523		580
524	Returns an object of class L<IO::AIO::GRP>. See its documentation below	581	Returns an object of class L<IO::AIO::GRP>. See its documentation below
525	for more info.	582	for more info.
526		583
527	Example:	584	Example:
…		…
533	add $grp	590	add $grp
534	(aio_stat ...),	591	(aio_stat ...),
535	(aio_stat ...),	592	(aio_stat ...),
536	...;	593	...;
537		594
		595	=item aio_nop $callback->()
		596
		597	This is a special request - it does nothing in itself and is only used for
		598	side effects, such as when you want to add a dummy request to a group so
		599	that finishing the requests in the group depends on executing the given
		600	code.
		601
		602	While this request does nothing, it still goes through the execution
		603	phase and still requires a worker thread. Thus, the callback will not
		604	be executed immediately but only after other requests in the queue have
		605	entered their execution phase. This can be used to measure request
		606	latency.
		607
538	=item IO::AIO::aio_sleep $fractional_seconds, $callback->() NOT EXPORTED	608	=item IO::AIO::aio_busy $fractional_seconds, $callback->() NOT EXPORTED
539		609
540	Mainly used for debugging and benchmarking, this aio request puts one of	610	Mainly used for debugging and benchmarking, this aio request puts one of
541	the request workers to sleep for the given time.	611	the request workers to sleep for the given time.
542		612
543	While it is theoretically handy to have simple I/O scheduling requests	613	While it is theoretically handy to have simple I/O scheduling requests
544	like sleep and file handle readable/writable, the overhead this creates	614	like sleep and file handle readable/writable, the overhead this creates is
545	is immense, so do not use this function except to put your application	615	immense (it blocks a thread for a long time) so do not use this function
546	under artificial I/O pressure.	616	except to put your application under artificial I/O pressure.
547		617
548	=back	618	=back
549		619
550	=head2 IO::AIO::REQ CLASS	620	=head2 IO::AIO::REQ CLASS
551		621
552	All non-aggregate C<aio_*> functions return an object of this class when	622	All non-aggregate C<aio_*> functions return an object of this class when
553	called in non-void context.	623	called in non-void context.
554		624
555	A request always moves through the following five states in its lifetime,
556	in order: B<ready> (request has been created, but has not been executed
557	yet), B<execute> (request is currently being executed), B<pending>
558	(request has been executed but callback has not been called yet),
559	B<result> (results are being processed synchronously, includes calling the
560	callback) and B<done> (request has reached the end of its lifetime and
561	holds no resources anymore).
562
563	=over 4	625	=over 4
564		626
565	=item $req->cancel	627	=item cancel $req
566		628
567	Cancels the request, if possible. Has the effect of skipping execution	629	Cancels the request, if possible. Has the effect of skipping execution
568	when entering the B<execute> state and skipping calling the callback when	630	when entering the B<execute> state and skipping calling the callback when
569	entering the the B<result> state, but will leave the request otherwise	631	entering the the B<result> state, but will leave the request otherwise
570	untouched. That means that requests that currently execute will not be	632	untouched. That means that requests that currently execute will not be
571	stopped and resources held by the request will not be freed prematurely.	633	stopped and resources held by the request will not be freed prematurely.
572		634
		635	=item cb $req $callback->(...)
		636
		637	Replace (or simply set) the callback registered to the request.
		638
573	=back	639	=back
574		640
575	=head2 IO::AIO::GRP CLASS	641	=head2 IO::AIO::GRP CLASS
576		642
577	This class is a subclass of L<IO::AIO::REQ>, so all its methods apply to	643	This class is a subclass of L<IO::AIO::REQ>, so all its methods apply to
…		…
603	};	669	};
604		670
605	This makes it very easy to create composite requests (see the source of	671	This makes it very easy to create composite requests (see the source of
606	C<aio_move> for an application) that work and feel like simple requests.	672	C<aio_move> for an application) that work and feel like simple requests.
607		673
		674	=over 4
		675
608	The IO::AIO::GRP objects will be cleaned up during calls to	676	=item * The IO::AIO::GRP objects will be cleaned up during calls to
609	C<IO::AIO::poll_cb>, just like any other request.	677	C<IO::AIO::poll_cb>, just like any other request.
610		678
611	They can be canceled like any other request. Canceling will cancel not	679	=item * They can be canceled like any other request. Canceling will cancel not
612	only the request itself, but also all requests it contains.	680	only the request itself, but also all requests it contains.
613		681
614	They can also can also be added to other IO::AIO::GRP objects.	682	=item * They can also can also be added to other IO::AIO::GRP objects.
615		683
616	You must not add requests to a group from within the group callback (or	684	=item * You must not add requests to a group from within the group callback (or
617	any later time).	685	any later time).
		686
		687	=back
618		688
619	Their lifetime, simplified, looks like this: when they are empty, they	689	Their lifetime, simplified, looks like this: when they are empty, they
620	will finish very quickly. If they contain only requests that are in the	690	will finish very quickly. If they contain only requests that are in the
621	C<done> state, they will also finish. Otherwise they will continue to	691	C<done> state, they will also finish. Otherwise they will continue to
622	exist.	692	exist.
…		…
626	group. And only when all those requests have finished will the the group	696	group. And only when all those requests have finished will the the group
627	itself finish.	697	itself finish.
628		698
629	=over 4	699	=over 4
630		700
		701	=item add $grp ...
		702
631	=item $grp->add (...)	703	=item $grp->add (...)
632
633	=item add $grp ...
634		704
635	Add one or more requests to the group. Any type of L<IO::AIO::REQ> can	705	Add one or more requests to the group. Any type of L<IO::AIO::REQ> can
636	be added, including other groups, as long as you do not create circular	706	be added, including other groups, as long as you do not create circular
637	dependencies.	707	dependencies.
638		708
639	Returns all its arguments.	709	Returns all its arguments.
640		710
		711	=item $grp->cancel_subs
		712
		713	Cancel all subrequests and clears any feeder, but not the group request
		714	itself. Useful when you queued a lot of events but got a result early.
		715
641	=item $grp->result (...)	716	=item $grp->result (...)
642		717
643	Set the result value(s) that will be passed to the group callback when all	718	Set the result value(s) that will be passed to the group callback when all
644	subrequests have finished. By default, no argument will be passed.	719	subrequests have finished. By default, no argument will be passed.
645		720
646	=item $grp->set_feeder ($callback->($grp))	721	=item feed $grp $callback->($grp)
647
648	[VERY EXPERIMENTAL]
649		722
650	Sets a feeder/generator on this group: every group can have an attached	723	Sets a feeder/generator on this group: every group can have an attached
651	generator that generates requests if idle. The idea behind this is that,	724	generator that generates requests if idle. The idea behind this is that,
652	although you could just queue as many requests as you want in a group,	725	although you could just queue as many requests as you want in a group,
653	this might starve other requests for a potentially long time. For	726	this might starve other requests for a potentially long time. For
654	example, C<aio_scandir> might generate hundreds of thousands C<aio_stat>	727	example, C<aio_scandir> might generate hundreds of thousands C<aio_stat>
655	requests, delaying any later requests for a long time.	728	requests, delaying any later requests for a long time.
656		729
657	To avoid this, and allow incremental generation of requests, you can	730	To avoid this, and allow incremental generation of requests, you can
658	instead a group and set a feeder on it that generates those requests. The	731	instead a group and set a feeder on it that generates those requests. The
659	feeder will be called whenever there are few enough (see C<feeder_limit>,	732	feed callback will be called whenever there are few enough (see C<limit>,
660	below) requests active in the group itself and is expected to queue more	733	below) requests active in the group itself and is expected to queue more
661	requests.	734	requests.
662		735
663	The feeder can queue as many requests as it likes (i.e. C<add> does not	736	The feed callback can queue as many requests as it likes (i.e. C<add> does
664	impose any limits).	737	not impose any limits).
665		738
666	If the feeder does not queue more requests when called, it will be	739	If the feed does not queue more requests when called, it will be
667	automatically removed from the group.	740	automatically removed from the group.
668		741
669	If the feeder limit is C<0>, it will be set to C<2> automatically.	742	If the feed limit is C<0>, it will be set to C<2> automatically.
670		743
671	Example:	744	Example:
672		745
673	# stat all files in @files, but only ever use four aio requests concurrently:	746	# stat all files in @files, but only ever use four aio requests concurrently:
674		747
675	my $grp = aio_group sub { print "finished\n" };	748	my $grp = aio_group sub { print "finished\n" };
676	$grp->feeder_limit (4);	749	limit $grp 4;
677	$grp->set_feeder (sub {	750	feed $grp sub {
678	my $file = pop @files	751	my $file = pop @files
679	or return;	752	or return;
680		753
681	add $grp aio_stat $file, sub { ... };	754	add $grp aio_stat $file, sub { ... };
682	});	755	};
683		756
684	=item $grp->feeder_limit ($num)	757	=item limit $grp $num
685		758
686	Sets the feeder limit for the group: The feeder will be called whenever	759	Sets the feeder limit for the group: The feeder will be called whenever
687	the group contains less than this many requests.	760	the group contains less than this many requests.
688		761
689	Setting the limit to C<0> will pause the feeding process.	762	Setting the limit to C<0> will pause the feeding process.
…		…
707		780
708	Process all outstanding events on the result pipe. You have to call this	781	Process all outstanding events on the result pipe. You have to call this
709	regularly. Returns the number of events processed. Returns immediately	782	regularly. Returns the number of events processed. Returns immediately
710	when no events are outstanding.	783	when no events are outstanding.
711		784
		785	If not all requests were processed for whatever reason, the filehandle
		786	will still be ready when C<poll_cb> returns.
		787
712	Example: Install an Event watcher that automatically calls	788	Example: Install an Event watcher that automatically calls
713	IO::AIO::poll_cb with high priority:	789	IO::AIO::poll_cb with high priority:
714		790
715	Event->io (fd => IO::AIO::poll_fileno,	791	Event->io (fd => IO::AIO::poll_fileno,
716	poll => 'r', async => 1,	792	poll => 'r', async => 1,
717	cb => \&IO::AIO::poll_cb);	793	cb => \&IO::AIO::poll_cb);
		794
		795	=item IO::AIO::poll_some $max_requests
		796
		797	Similar to C<poll_cb>, but only processes up to C<$max_requests> requests
		798	at a time.
		799
		800	Useful if you want to ensure some level of interactiveness when perl is
		801	not fast enough to process all requests in time.
		802
		803	Example: Install an Event watcher that automatically calls
		804	IO::AIO::poll_some with low priority, to ensure that other parts of the
		805	program get the CPU sometimes even under high AIO load.
		806
		807	Event->io (fd => IO::AIO::poll_fileno,
		808	poll => 'r', nice => 1,
		809	cb => sub { IO::AIO::poll_some 256 });
718		810
719	=item IO::AIO::poll_wait	811	=item IO::AIO::poll_wait
720		812
721	Wait till the result filehandle becomes ready for reading (simply does a	813	Wait till the result filehandle becomes ready for reading (simply does a
722	C<select> on the filehandle. This is useful if you want to synchronously wait	814	C<select> on the filehandle. This is useful if you want to synchronously wait
…		…
784		876
785	Under normal circumstances you don't need to call this function.	877	Under normal circumstances you don't need to call this function.
786		878
787	=item $oldnreqs = IO::AIO::max_outstanding $nreqs	879	=item $oldnreqs = IO::AIO::max_outstanding $nreqs
788		880
		881	[REMOVED]
		882
		883	Pre-2.x versions used max_outstanding for a crude request queue length limit.
		884
		885	In 2.x+ you are advised to use a group and a feeder to limit
		886	concurrency. The max_outstanding feature ran very unstable (endless
		887	recursions causing segfaults, bad interaction with groups etc.) and was
		888	removed.
		889
		890	I am deeply sorry, but I am still on the hunt for a good limiting interface.
		891
		892	Original description was as follows:
		893
789	Sets the maximum number of outstanding requests to C<$nreqs>. If you	894	Sets the maximum number of outstanding requests to C<$nreqs>. If you try
790	try to queue up more than this number of requests, the caller will block until	895	to queue up more than this number of requests, the caller will block until
791	some requests have been handled.	896	some requests have been handled.
792
793	The default is very large, so normally there is no practical limit. If you
794	queue up many requests in a loop it often improves speed if you set
795	this to a relatively low number, such as C<100>.
796
797	Under normal circumstances you don't need to call this function.
798		897
799	=back	898	=back
800		899
801	=cut	900	=cut
802		901
…		…
829	This module should do "the right thing" when the process using it forks:	928	This module should do "the right thing" when the process using it forks:
830		929
831	Before the fork, IO::AIO enters a quiescent state where no requests	930	Before the fork, IO::AIO enters a quiescent state where no requests
832	can be added in other threads and no results will be processed. After	931	can be added in other threads and no results will be processed. After
833	the fork the parent simply leaves the quiescent state and continues	932	the fork the parent simply leaves the quiescent state and continues
834	request/result processing, while the child clears the request/result	933	request/result processing, while the child frees the request/result queue
835	queue (so the requests started before the fork will only be handled in	934	(so that the requests started before the fork will only be handled in the
836	the parent). Threads will be started on demand until the limit ste in the	935	parent). Threads will be started on demand until the limit set in the
837	parent process has been reached again.	936	parent process has been reached again.
838		937
839	In short: the parent will, after a short pause, continue as if fork had	938	In short: the parent will, after a short pause, continue as if fork had
840	not been called, while the child will act as if IO::AIO has not been used	939	not been called, while the child will act as if IO::AIO has not been used
841	yet.	940	yet.
842		941
843	=head2 MEMORY USAGE	942	=head2 MEMORY USAGE
844		943
		944	Per-request usage:
		945
845	Each aio request uses - depending on your architecture - around 128 bytes	946	Each aio request uses - depending on your architecture - around 100-200
846	of memory. In addition, stat requests need a stat buffer (possibly a few	947	bytes of memory. In addition, stat requests need a stat buffer (possibly
847	hundred bytes). Perl scalars and other data passed into aio requests will	948	a few hundred bytes), readdir requires a result buffer and so on. Perl
848	also be locked.	949	scalars and other data passed into aio requests will also be locked and
		950	will consume memory till the request has entered the done state.
849		951
850	This is now awfully much, so queuing lots of requests is not usually a	952	This is now awfully much, so queuing lots of requests is not usually a
851	problem.	953	problem.
852		954
853	Each thread needs a stack area which is usually around 16k, sometimes much	955	Per-thread usage:
854	larger, depending on the OS.	956
		957	In the execution phase, some aio requests require more memory for
		958	temporary buffers, and each thread requires a stack and other data
		959	structures (usually around 16k-128k, depending on the OS).
		960
		961	=head1 KNOWN BUGS
		962
		963	Known bugs will be fixed in the next release.
855		964
856	=head1 SEE ALSO	965	=head1 SEE ALSO
857		966
858	L<Coro>, L<Linux::AIO> (obsolete).	967	L<Coro::AIO>.
859		968
860	=head1 AUTHOR	969	=head1 AUTHOR
861		970
862	Marc Lehmann <schmorp@schmorp.de>	971	Marc Lehmann <schmorp@schmorp.de>
863	http://home.schmorp.de/	972	http://home.schmorp.de/

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Comparing IO-AIO/AIO.pm (file contents): Revision 1.61 by root, Sun Oct 22 13:52:11 2006 UTC vs. Revision 1.78 by root, Thu Oct 26 12:38:04 2006 UTC

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Comparing IO-AIO/AIO.pm (file contents):
Revision 1.61 by root, Sun Oct 22 13:52:11 2006 UTC vs.
Revision 1.78 by root, Thu Oct 26 12:38:04 2006 UTC