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

Comparing IO-AIO/AIO.pm (file contents):
Revision 1.71 by root, Tue Oct 24 11:57:30 2006 UTC vs.
Revision 1.79 by root, Thu Oct 26 14:35:34 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
…		…
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 aioreq_nice));	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);
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);
…		…
375	with the filenames.	426	with the filenames.
376		427
377	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	428	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
378		429
379	Scans a directory (similar to C<aio_readdir>) but additionally tries to	430	Scans a directory (similar to C<aio_readdir>) but additionally tries to
380	separate the entries of directory C<$path> into two sets of names, ones	431	efficiently separate the entries of directory C<$path> into two sets of
381	you can recurse into (directories or links to them), and ones you cannot	432	names, directories you can recurse into (directories), and ones you cannot
382	recurse into (everything else).	433	recurse into (everything else, including symlinks to directories).
383		434
384	C<aio_scandir> is a composite request that creates of many sub requests_	435	C<aio_scandir> is a composite request that creates of many sub requests_
385	C<$maxreq> specifies the maximum number of outstanding aio requests that	436	C<$maxreq> specifies the maximum number of outstanding aio requests that
386	this function generates. If it is C<< <= 0 >>, then a suitable default	437	this function generates. If it is C<< <= 0 >>, then a suitable default
387	will be chosen (currently 6).	438	will be chosen (currently 6).
…		…
469	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],	520	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
470	@$entries];	521	@$entries];
471		522
472	my (@dirs, @nondirs);	523	my (@dirs, @nondirs);
473		524
474	my ($statcb, $schedcb);
475	my $nreq = 0;
476
477	my $statgrp = add $grp aio_group;	525	my $statgrp = add $grp aio_group sub {
		526	$grp->result (\@dirs, \@nondirs);
		527	};
478		528
479	$schedcb = sub {	529	limit $statgrp $maxreq;
480	if (@$entries) {	530	feed $statgrp sub {
481	if ($nreq < $maxreq) {	531	return unless @$entries;
482	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	}
483	$nreq++;	550	}
484	add $statgrp aio_stat "$path/$ent/.", sub { $statcb->($_[0], $ent) };
485	}	551	}
486	} elsif (!$nreq) {
487	# finished
488	$statgrp->cancel;
489	undef $statcb;
490	undef $schedcb;
491	$grp->result (\@dirs, \@nondirs);
492	}	552	};
493	};	553	};
494	$statcb = sub {
495	my ($status, $entry) = @_;
496
497	if ($status < 0) {
498	$nreq--;
499	push @nondirs, $entry;
500	&$schedcb;
501	} else {
502	# need to check for real directory
503	add $grp aio_lstat "$path/$entry", sub {
504	$nreq--;
505
506	if (-d _) {
507	push @dirs, $entry;
508
509	if (!--$ndirs) {
510	push @nondirs, @$entries;
511	$entries = [];
512	}
513	} else {
514	push @nondirs, $entry;
515	}
516
517	&$schedcb;
518	}
519	}
520	};
521
522	&$schedcb while @$entries && $nreq < $maxreq;
523	};	554	};
524	};	555	};
525	};	556	};
526		557
527	$grp	558	$grp
…		…
539		570
540	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
541	detected, it will be emulated by calling C<fsync> instead.	572	detected, it will be emulated by calling C<fsync> instead.
542		573
543	=item aio_group $callback->(...)	574	=item aio_group $callback->(...)
544
545	[EXPERIMENTAL]
546		575
547	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
548	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
549	many requests into a single, composite, request with a definite callback	578	many requests into a single, composite, request with a definite callback
550	and the ability to cancel the whole request with its subrequests.	579	and the ability to cancel the whole request with its subrequests.
…		…
591	=head2 IO::AIO::REQ CLASS	620	=head2 IO::AIO::REQ CLASS
592		621
593	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
594	called in non-void context.	623	called in non-void context.
595		624
596	A request always moves through the following five states in its lifetime,
597	in order: B<ready> (request has been created, but has not been executed
598	yet), B<execute> (request is currently being executed), B<pending>
599	(request has been executed but callback has not been called yet),
600	B<result> (results are being processed synchronously, includes calling the
601	callback) and B<done> (request has reached the end of its lifetime and
602	holds no resources anymore).
603
604	=over 4	625	=over 4
605		626
606	=item cancel $req	627	=item cancel $req
607		628
608	Cancels the request, if possible. Has the effect of skipping execution	629	Cancels the request, if possible. Has the effect of skipping execution
…		…
661	=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.
662		683
663	=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
664	any later time).	685	any later time).
665		686
666	=item * This does not harmonise well with C<max_outstanding>, so best do
667	not combine C<aio_group> with it. Groups and feeders are recommended for
668	this kind of concurrency-limiting.
669
670	=back	687	=back
671		688
672	Their lifetime, simplified, looks like this: when they are empty, they	689	Their lifetime, simplified, looks like this: when they are empty, they
673	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
674	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
…		…
689	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
690	dependencies.	707	dependencies.
691		708
692	Returns all its arguments.	709	Returns all its arguments.
693		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
694	=item $grp->result (...)	716	=item $grp->result (...)
695		717
696	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
697	subrequests have finished. By default, no argument will be passed.	719	subrequests have finished. By default, no argument will be passed.
698		720
699	=item feed $grp $callback->($grp)	721	=item feed $grp $callback->($grp)
700
701	[VERY EXPERIMENTAL]
702		722
703	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
704	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,
705	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,
706	this might starve other requests for a potentially long time. For	726	this might starve other requests for a potentially long time. For
…		…
760		780
761	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
762	regularly. Returns the number of events processed. Returns immediately	782	regularly. Returns the number of events processed. Returns immediately
763	when no events are outstanding.	783	when no events are outstanding.
764		784
		785	If not all requests were processed for whatever reason, the filehandle
		786	will still be ready when C<poll_cb> returns.
		787
765	Example: Install an Event watcher that automatically calls	788	Example: Install an Event watcher that automatically calls
766	IO::AIO::poll_cb with high priority:	789	IO::AIO::poll_cb with high priority:
767		790
768	Event->io (fd => IO::AIO::poll_fileno,	791	Event->io (fd => IO::AIO::poll_fileno,
769	poll => 'r', async => 1,	792	poll => 'r', async => 1,
770	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 });
771		810
772	=item IO::AIO::poll_wait	811	=item IO::AIO::poll_wait
773		812
774	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
775	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
…		…
835	This module automatically runs C<max_parallel 0> at program end, to ensure	874	This module automatically runs C<max_parallel 0> at program end, to ensure
836	that all threads are killed and that there are no outstanding requests.	875	that all threads are killed and that there are no outstanding requests.
837		876
838	Under normal circumstances you don't need to call this function.	877	Under normal circumstances you don't need to call this function.
839		878
840	=item $oldnreqs = IO::AIO::max_outstanding $nreqs	879	=item $oldmaxreqs = IO::AIO::max_outstanding $maxreqs
841		880
842	[DEPRECATED]	881	This is a very bad function to use in interactive programs because it
		882	blocks, and a bad way to reduce concurrency because it is inexact: Better
		883	use an C<aio_group> together with a feed callback.
843		884
844	Sets the maximum number of outstanding requests to C<$nreqs>. If you	885	Sets the maximum number of outstanding requests to C<$nreqs>. If you
845	try to queue up more than this number of requests, the caller will block until	886	to queue up more than this number of requests, the next call to the
846	some requests have been handled.	887	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
		888	function will block until the limit is no longer exceeded.
847		889
848	The default is very large, so normally there is no practical limit. If you	890	The default value is very large, so there is no practical limit on the
849	queue up many requests in a loop it often improves speed if you set	891	number of outstanding requests.
850	this to a relatively low number, such as C<100>.
851		892
852	This function does not work well together with C<aio_group>'s, and their	893	You can still queue as many requests as you want. Therefore,
853	feeder interface is better suited to limiting concurrency, so do not use	894	C<max_oustsanding> is mainly useful in simple scripts (with low values) or
854	this function.	895	as a stop gap to shield against fatal memory overflow (with large values).
855
856	Under normal circumstances you don't need to call this function.
857		896
858	=back	897	=back
859		898
860	=cut	899	=cut
861		900
…		…
888	This module should do "the right thing" when the process using it forks:	927	This module should do "the right thing" when the process using it forks:
889		928
890	Before the fork, IO::AIO enters a quiescent state where no requests	929	Before the fork, IO::AIO enters a quiescent state where no requests
891	can be added in other threads and no results will be processed. After	930	can be added in other threads and no results will be processed. After
892	the fork the parent simply leaves the quiescent state and continues	931	the fork the parent simply leaves the quiescent state and continues
893	request/result processing, while the child clears the request/result	932	request/result processing, while the child frees the request/result queue
894	queue (so the requests started before the fork will only be handled in	933	(so that the requests started before the fork will only be handled in the
895	the parent). Threads will be started on demand until the limit ste in the	934	parent). Threads will be started on demand until the limit set in the
896	parent process has been reached again.	935	parent process has been reached again.
897		936
898	In short: the parent will, after a short pause, continue as if fork had	937	In short: the parent will, after a short pause, continue as if fork had
899	not been called, while the child will act as if IO::AIO has not been used	938	not been called, while the child will act as if IO::AIO has not been used
900	yet.	939	yet.
901		940
902	=head2 MEMORY USAGE	941	=head2 MEMORY USAGE
903		942
		943	Per-request usage:
		944
904	Each aio request uses - depending on your architecture - around 128 bytes	945	Each aio request uses - depending on your architecture - around 100-200
905	of memory. In addition, stat requests need a stat buffer (possibly a few	946	bytes of memory. In addition, stat requests need a stat buffer (possibly
906	hundred bytes). Perl scalars and other data passed into aio requests will	947	a few hundred bytes), readdir requires a result buffer and so on. Perl
907	also be locked.	948	scalars and other data passed into aio requests will also be locked and
		949	will consume memory till the request has entered the done state.
908		950
909	This is now awfully much, so queuing lots of requests is not usually a	951	This is now awfully much, so queuing lots of requests is not usually a
910	problem.	952	problem.
911		953
912	Each thread needs a stack area which is usually around 16k, sometimes much	954	Per-thread usage:
913	larger, depending on the OS.	955
		956	In the execution phase, some aio requests require more memory for
		957	temporary buffers, and each thread requires a stack and other data
		958	structures (usually around 16k-128k, depending on the OS).
		959
		960	=head1 KNOWN BUGS
		961
		962	Known bugs will be fixed in the next release.
914		963
915	=head1 SEE ALSO	964	=head1 SEE ALSO
916		965
917	L<Coro::AIO>.	966	L<Coro::AIO>.
918		967

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Comparing IO-AIO/AIO.pm (file contents): Revision 1.71 by root, Tue Oct 24 11:57:30 2006 UTC vs. Revision 1.79 by root, Thu Oct 26 14:35:34 2006 UTC

Diff Legend

Comparing IO-AIO/AIO.pm (file contents):
Revision 1.71 by root, Tue Oct 24 11:57:30 2006 UTC vs.
Revision 1.79 by root, Thu Oct 26 14:35:34 2006 UTC