[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 1.77 by root, Wed Oct 25 17:57:30 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);
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);
…		…
133	respectively. Requests with higher priority will be serviced first.	184	respectively. Requests with higher priority will be serviced first.
134		185
135	The priority will be reset to C<0> after each call to one of the C<aio_>	186	The priority will be reset to C<0> after each call to one of the C<aio_>
136	functions.	187	functions.
137		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
138	=item aio_open $pathname, $flags, $mode, $callback->($fh)	208	=item aio_open $pathname, $flags, $mode, $callback->($fh)
139		209
140	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
141	created filehandle for the file.	211	created filehandle for the file.
142		212
…		…
193	$_[0] > 0 or die "read error: $!";	263	$_[0] > 0 or die "read error: $!";
194	print "read $_[0] bytes: <$buffer>\n";	264	print "read $_[0] bytes: <$buffer>\n";
195	};	265	};
196		266
197	=item aio_move $srcpath, $dstpath, $callback->($status)	267	=item aio_move $srcpath, $dstpath, $callback->($status)
198
199	[EXPERIMENTAL due to internal aio_group use]
200		268
201	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
202	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
203	the C<0> (error) or C<-1> ok.	271	the C<0> (error) or C<-1> ok.
204		272
…		…
357	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
358	with the filenames.	426	with the filenames.
359		427
360	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	428	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
361		429
362	[EXPERIMENTAL due to internal aio_group use]
363
364	Scans a directory (similar to C<aio_readdir>) but additionally tries to	430	Scans a directory (similar to C<aio_readdir>) but additionally tries to
365	separate the entries of directory C<$path> into two sets of names, ones	431	efficiently separate the entries of directory C<$path> into two sets of
366	you can recurse into (directories or links to them), and ones you cannot	432	names, directories you can recurse into (directories), and ones you cannot
367	recurse into (everything else).	433	recurse into (everything else, including symlinks to directories).
368		434
369	C<aio_scandir> is a composite request that creates of many sub requests_	435	C<aio_scandir> is a composite request that creates of many sub requests_
370	C<$maxreq> specifies the maximum number of outstanding aio requests that	436	C<$maxreq> specifies the maximum number of outstanding aio requests that
371	this function generates. If it is C<< <= 0 >>, then a suitable default	437	this function generates. If it is C<< <= 0 >>, then a suitable default
372	will be chosen (currently 6).	438	will be chosen (currently 6).
…		…
454	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],	520	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
455	@$entries];	521	@$entries];
456		522
457	my (@dirs, @nondirs);	523	my (@dirs, @nondirs);
458		524
459	my ($statcb, $schedcb);
460	my $nreq = 0;
461
462	my $statgrp = add $grp aio_group;	525	my $statgrp = add $grp aio_group sub {
		526	$grp->result (\@dirs, \@nondirs);
		527	};
463		528
464	$schedcb = sub {	529	limit $statgrp $maxreq;
465	if (@$entries) {	530	feed $statgrp sub {
466	if ($nreq < $maxreq) {	531	return unless @$entries;
467	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	}
468	$nreq++;	550	}
469	add $statgrp aio_stat "$path/$ent/.", sub { $statcb->($_[0], $ent) };
470	}	551	}
471	} elsif (!$nreq) {
472	# finished
473	$statgrp->cancel;
474	undef $statcb;
475	undef $schedcb;
476	$grp->result (\@dirs, \@nondirs);
477	}	552	};
478	};	553	};
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	};	554	};
509	};	555	};
510	};	556	};
511		557
512	$grp	558	$grp
…		…
525	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
526	detected, it will be emulated by calling C<fsync> instead.	572	detected, it will be emulated by calling C<fsync> instead.
527		573
528	=item aio_group $callback->(...)	574	=item aio_group $callback->(...)
529		575
530	[EXPERIMENTAL]
531
532	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
533	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
534	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.
535		580
536	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
537	for more info.	582	for more info.
538		583
539	Example:	584	Example:
…		…
558	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
559	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
560	entered their execution phase. This can be used to measure request	605	entered their execution phase. This can be used to measure request
561	latency.	606	latency.
562		607
563	=item IO::AIO::aio_sleep $fractional_seconds, $callback->() NOT EXPORTED	608	=item IO::AIO::aio_busy $fractional_seconds, $callback->() NOT EXPORTED
564		609
565	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
566	the request workers to sleep for the given time.	611	the request workers to sleep for the given time.
567		612
568	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
569	like sleep and file handle readable/writable, the overhead this creates	614	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	615	immense (it blocks a thread for a long time) so do not use this function
571	under artificial I/O pressure.	616	except to put your application under artificial I/O pressure.
572		617
573	=back	618	=back
574		619
575	=head2 IO::AIO::REQ CLASS	620	=head2 IO::AIO::REQ CLASS
576		621
577	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
578	called in non-void context.	623	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		624
588	=over 4	625	=over 4
589		626
590	=item cancel $req	627	=item cancel $req
591		628
…		…
645	=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.
646		683
647	=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
648	any later time).	685	any later time).
649		686
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	687	=back
655		688
656	Their lifetime, simplified, looks like this: when they are empty, they	689	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	690	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	691	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	706	be added, including other groups, as long as you do not create circular
674	dependencies.	707	dependencies.
675		708
676	Returns all its arguments.	709	Returns all its arguments.
677		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
678	=item $grp->result (...)	716	=item $grp->result (...)
679		717
680	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
681	subrequests have finished. By default, no argument will be passed.	719	subrequests have finished. By default, no argument will be passed.
682		720
683	=item feed $grp $callback->($grp)	721	=item feed $grp $callback->($grp)
684
685	[VERY EXPERIMENTAL]
686		722
687	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
688	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,
689	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,
690	this might starve other requests for a potentially long time. For	726	this might starve other requests for a potentially long time. For
…		…
821		857
822	Under normal circumstances you don't need to call this function.	858	Under normal circumstances you don't need to call this function.
823		859
824	=item $oldnreqs = IO::AIO::max_outstanding $nreqs	860	=item $oldnreqs = IO::AIO::max_outstanding $nreqs
825		861
826	[DEPRECATED]	862	[REMOVED]
827		863
		864	Pre-2.x versions used max_outstanding for a crude request queue length limit.
		865
		866	In 2.x+ you are advised to use a group and a feeder to limit
		867	concurrency. The max_outstanding feature ran very unstable (endless
		868	recursions causing segfaults, bad interaction with groups etc.) and was
		869	removed.
		870
		871	I am deeply sorry, but I am still on the hunt for a good limiting interface.
		872
		873	Original description was as follows:
		874
828	Sets the maximum number of outstanding requests to C<$nreqs>. If you	875	Sets the maximum number of outstanding requests to C<$nreqs>. If you try
829	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
830	some requests have been handled.	877	some requests have been handled.
831
832	The default is very large, so normally there is no practical limit. If you
833	queue up many requests in a loop it often improves speed if you set
834	this to a relatively low number, such as C<100>.
835
836	This function does not work well together with C<aio_group>'s, and their
837	feeder interface is better suited to limiting concurrency, so do not use
838	this function.
839
840	Under normal circumstances you don't need to call this function.
841		878
842	=back	879	=back
843		880
844	=cut	881	=cut
845		882
…		…
872	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:
873		910
874	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
875	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
876	the fork the parent simply leaves the quiescent state and continues	913	the fork the parent simply leaves the quiescent state and continues
877	request/result processing, while the child clears the request/result	914	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	915	(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	916	parent). Threads will be started on demand until the limit set in the
880	parent process has been reached again.	917	parent process has been reached again.
881		918
882	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
883	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
884	yet.	921	yet.
885		922
886	=head2 MEMORY USAGE	923	=head2 MEMORY USAGE
887		924
		925	Per-request usage:
		926
888	Each aio request uses - depending on your architecture - around 128 bytes	927	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	928	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	929	a few hundred bytes), readdir requires a result buffer and so on. Perl
891	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.
892		932
893	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
894	problem.	934	problem.
895		935
896	Each thread needs a stack area which is usually around 16k, sometimes much	936	Per-thread usage:
897	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.
898		945
899	=head1 SEE ALSO	946	=head1 SEE ALSO
900		947
901	L<Coro::AIO>.	948	L<Coro::AIO>.
902		949

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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 1.77 by root, Wed Oct 25 17:57:30 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 1.77 by root, Wed Oct 25 17:57:30 2006 UTC