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

Comparing IO-AIO/AIO.pm (file contents):
Revision 1.65 by root, Mon Oct 23 14:49:51 2006 UTC vs.
Revision 1.77 by root, Wed Oct 25 17:57:30 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 aio_nop);	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:
…		…
546	phase and still requires a worker thread. Thus, the callback will not	603	phase and still requires a worker thread. Thus, the callback will not
547	be executed immediately but only after other requests in the queue have	604	be executed immediately but only after other requests in the queue have
548	entered their execution phase. This can be used to measure request	605	entered their execution phase. This can be used to measure request
549	latency.	606	latency.
550		607
551	=item IO::AIO::aio_sleep $fractional_seconds, $callback->() NOT EXPORTED	608	=item IO::AIO::aio_busy $fractional_seconds, $callback->() NOT EXPORTED
552		609
553	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
554	the request workers to sleep for the given time.	611	the request workers to sleep for the given time.
555		612
556	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
557	like sleep and file handle readable/writable, the overhead this creates	614	like sleep and file handle readable/writable, the overhead this creates is
558	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
559	under artificial I/O pressure.	616	except to put your application under artificial I/O pressure.
560		617
561	=back	618	=back
562		619
563	=head2 IO::AIO::REQ CLASS	620	=head2 IO::AIO::REQ CLASS
564		621
565	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
566	called in non-void context.	623	called in non-void context.
567
568	A request always moves through the following five states in its lifetime,
569	in order: B<ready> (request has been created, but has not been executed
570	yet), B<execute> (request is currently being executed), B<pending>
571	(request has been executed but callback has not been called yet),
572	B<result> (results are being processed synchronously, includes calling the
573	callback) and B<done> (request has reached the end of its lifetime and
574	holds no resources anymore).
575		624
576	=over 4	625	=over 4
577		626
578	=item cancel $req	627	=item cancel $req
579		628
…		…
633	=item * 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.
634		683
635	=item * 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
636	any later time).	685	any later time).
637		686
638	=item * This does not harmonise well with C<max_outstanding>, so best do
639	not combine C<aio_group> with it. Groups and feeders are recommended for
640	this kind of concurrency-limiting.
641
642	=back	687	=back
643		688
644	Their lifetime, simplified, looks like this: when they are empty, they	689	Their lifetime, simplified, looks like this: when they are empty, they
645	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
646	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
…		…
661	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
662	dependencies.	707	dependencies.
663		708
664	Returns all its arguments.	709	Returns all its arguments.
665		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
666	=item $grp->result (...)	716	=item $grp->result (...)
667		717
668	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
669	subrequests have finished. By default, no argument will be passed.	719	subrequests have finished. By default, no argument will be passed.
670		720
671	=item feed $grp $callback->($grp)	721	=item feed $grp $callback->($grp)
672
673	[VERY EXPERIMENTAL]
674		722
675	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
676	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,
677	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,
678	this might starve other requests for a potentially long time. For	726	this might starve other requests for a potentially long time. For
679	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>
680	requests, delaying any later requests for a long time.	728	requests, delaying any later requests for a long time.
681		729
682	To avoid this, and allow incremental generation of requests, you can	730	To avoid this, and allow incremental generation of requests, you can
683	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
684	feed callback will be called whenever there are few enough (see C<feed_limit>,	732	feed callback will be called whenever there are few enough (see C<limit>,
685	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
686	requests.	734	requests.
687		735
688	The feed 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
689	impose any limits).	737	not impose any limits).
690		738
691	If the feed does not queue more requests when called, it will be	739	If the feed does not queue more requests when called, it will be
692	automatically removed from the group.	740	automatically removed from the group.
693		741
694	If the feed 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.
…		…
696	Example:	744	Example:
697		745
698	# 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:
699		747
700	my $grp = aio_group sub { print "finished\n" };	748	my $grp = aio_group sub { print "finished\n" };
701	feed_limit $grp 4;	749	limit $grp 4;
702	feed $grp sub {	750	feed $grp sub {
703	my $file = pop @files	751	my $file = pop @files
704	or return;	752	or return;
705		753
706	add $grp aio_stat $file, sub { ... };	754	add $grp aio_stat $file, sub { ... };
707	};	755	};
708		756
709	=item feed_limit $grp $num	757	=item limit $grp $num
710		758
711	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
712	the group contains less than this many requests.	760	the group contains less than this many requests.
713		761
714	Setting the limit to C<0> will pause the feeding process.	762	Setting the limit to C<0> will pause the feeding process.
…		…
809		857
810	Under normal circumstances you don't need to call this function.	858	Under normal circumstances you don't need to call this function.
811		859
812	=item $oldnreqs = IO::AIO::max_outstanding $nreqs	860	=item $oldnreqs = IO::AIO::max_outstanding $nreqs
813		861
814	[DEPRECATED]	862	[REMOVED]
815		863
		864	Pre-2.x versions used max_outstanding for a crude request queue length limit.
		865
		866	In 2.x+ you are advised to use a group and a feeder to limit
		867	concurrency. The max_outstanding feature ran very unstable (endless
		868	recursions causing segfaults, bad interaction with groups etc.) and was
		869	removed.
		870
		871	I am deeply sorry, but I am still on the hunt for a good limiting interface.
		872
		873	Original description was as follows:
		874
816	Sets the maximum number of outstanding requests to C<$nreqs>. If you	875	Sets the maximum number of outstanding requests to C<$nreqs>. If you try
817	try to queue up more than this number of requests, the caller will block until	876	to queue up more than this number of requests, the caller will block until
818	some requests have been handled.	877	some requests have been handled.
819
820	The default is very large, so normally there is no practical limit. If you
821	queue up many requests in a loop it often improves speed if you set
822	this to a relatively low number, such as C<100>.
823
824	This function does not work well together with C<aio_group>'s, and their
825	feeder interface is better suited to limiting concurrency, so do not use
826	this function.
827
828	Under normal circumstances you don't need to call this function.
829		878
830	=back	879	=back
831		880
832	=cut	881	=cut
833		882
…		…
860	This module should do "the right thing" when the process using it forks:	909	This module should do "the right thing" when the process using it forks:
861		910
862	Before the fork, IO::AIO enters a quiescent state where no requests	911	Before the fork, IO::AIO enters a quiescent state where no requests
863	can be added in other threads and no results will be processed. After	912	can be added in other threads and no results will be processed. After
864	the fork the parent simply leaves the quiescent state and continues	913	the fork the parent simply leaves the quiescent state and continues
865	request/result processing, while the child clears the request/result	914	request/result processing, while the child frees the request/result queue
866	queue (so the requests started before the fork will only be handled in	915	(so that the requests started before the fork will only be handled in the
867	the parent). Threads will be started on demand until the limit ste in the	916	parent). Threads will be started on demand until the limit set in the
868	parent process has been reached again.	917	parent process has been reached again.
869		918
870	In short: the parent will, after a short pause, continue as if fork had	919	In short: the parent will, after a short pause, continue as if fork had
871	not been called, while the child will act as if IO::AIO has not been used	920	not been called, while the child will act as if IO::AIO has not been used
872	yet.	921	yet.
873		922
874	=head2 MEMORY USAGE	923	=head2 MEMORY USAGE
875		924
		925	Per-request usage:
		926
876	Each aio request uses - depending on your architecture - around 128 bytes	927	Each aio request uses - depending on your architecture - around 100-200
877	of memory. In addition, stat requests need a stat buffer (possibly a few	928	bytes of memory. In addition, stat requests need a stat buffer (possibly
878	hundred bytes). Perl scalars and other data passed into aio requests will	929	a few hundred bytes), readdir requires a result buffer and so on. Perl
879	also be locked.	930	scalars and other data passed into aio requests will also be locked and
		931	will consume memory till the request has entered the done state.
880		932
881	This is now awfully much, so queuing lots of requests is not usually a	933	This is now awfully much, so queuing lots of requests is not usually a
882	problem.	934	problem.
883		935
884	Each thread needs a stack area which is usually around 16k, sometimes much	936	Per-thread usage:
885	larger, depending on the OS.	937
		938	In the execution phase, some aio requests require more memory for
		939	temporary buffers, and each thread requires a stack and other data
		940	structures (usually around 16k-128k, depending on the OS).
		941
		942	=head1 KNOWN BUGS
		943
		944	Known bugs will be fixed in the next release.
886		945
887	=head1 SEE ALSO	946	=head1 SEE ALSO
888		947
889	L<Coro>, L<Linux::AIO> (obsolete).	948	L<Coro::AIO>.
890		949
891	=head1 AUTHOR	950	=head1 AUTHOR
892		951
893	Marc Lehmann <schmorp@schmorp.de>	952	Marc Lehmann <schmorp@schmorp.de>
894	http://home.schmorp.de/	953	http://home.schmorp.de/

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Comparing IO-AIO/AIO.pm (file contents): Revision 1.65 by root, Mon Oct 23 14:49:51 2006 UTC vs. Revision 1.77 by root, Wed Oct 25 17:57:30 2006 UTC

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Comparing IO-AIO/AIO.pm (file contents):
Revision 1.65 by root, Mon Oct 23 14:49:51 2006 UTC vs.
Revision 1.77 by root, Wed Oct 25 17:57:30 2006 UTC