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

Comparing IO-AIO/AIO.pm (file contents):
Revision 1.63 by root, Mon Oct 23 00:34:36 2006 UTC vs.
Revision 1.75 by root, Tue Oct 24 20:10:26 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 max_outstanding 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	separate the entries of directory C<$path> into two sets of names, ones
354	you can recurse into (directories or links to them), and ones you cannot	432	you can recurse into (directories or links to them), and ones you cannot
355	recurse into (everything else).	433	recurse into (everything else).
356		434
…		…
442	map [$_, 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:
…		…
540	This is a special request - it does nothing in itself and is only used for	597	This is a special request - it does nothing in itself and is only used for
541	side effects, such as when you want to add a dummy request to a group so	598	side effects, such as when you want to add a dummy request to a group so
542	that finishing the requests in the group depends on executing the given	599	that finishing the requests in the group depends on executing the given
543	code.	600	code.
544		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
545	=item IO::AIO::aio_sleep $fractional_seconds, $callback->() NOT EXPORTED	608	=item IO::AIO::aio_busy $fractional_seconds, $callback->() NOT EXPORTED
546		609
547	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
548	the request workers to sleep for the given time.	611	the request workers to sleep for the given time.
549		612
550	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
551	like sleep and file handle readable/writable, the overhead this creates	614	like sleep and file handle readable/writable, the overhead this creates is
552	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
553	under artificial I/O pressure.	616	except to put your application under artificial I/O pressure.
554		617
555	=back	618	=back
556		619
557	=head2 IO::AIO::REQ CLASS	620	=head2 IO::AIO::REQ CLASS
558		621
559	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
560	called in non-void context.	623	called in non-void context.
561		624
562	A request always moves through the following five states in its lifetime,
563	in order: B<ready> (request has been created, but has not been executed
564	yet), B<execute> (request is currently being executed), B<pending>
565	(request has been executed but callback has not been called yet),
566	B<result> (results are being processed synchronously, includes calling the
567	callback) and B<done> (request has reached the end of its lifetime and
568	holds no resources anymore).
569
570	=over 4	625	=over 4
571		626
572	=item $req->cancel	627	=item cancel $req
573		628
574	Cancels the request, if possible. Has the effect of skipping execution	629	Cancels the request, if possible. Has the effect of skipping execution
575	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
576	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
577	untouched. That means that requests that currently execute will not be	632	untouched. That means that requests that currently execute will not be
578	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.
579		634
		635	=item cb $req $callback->(...)
		636
		637	Replace (or simply set) the callback registered to the request.
		638
580	=back	639	=back
581		640
582	=head2 IO::AIO::GRP CLASS	641	=head2 IO::AIO::GRP CLASS
583		642
584	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
…		…
641	group. And only when all those requests have finished will the the group	700	group. And only when all those requests have finished will the the group
642	itself finish.	701	itself finish.
643		702
644	=over 4	703	=over 4
645		704
		705	=item add $grp ...
		706
646	=item $grp->add (...)	707	=item $grp->add (...)
647
648	=item add $grp ...
649		708
650	Add one or more requests to the group. Any type of L<IO::AIO::REQ> can	709	Add one or more requests to the group. Any type of L<IO::AIO::REQ> can
651	be added, including other groups, as long as you do not create circular	710	be added, including other groups, as long as you do not create circular
652	dependencies.	711	dependencies.
653		712
654	Returns all its arguments.	713	Returns all its arguments.
655		714
		715	=item $grp->cancel_subs
		716
		717	Cancel all subrequests and clears any feeder, but not the group request
		718	itself. Useful when you queued a lot of events but got a result early.
		719
656	=item $grp->result (...)	720	=item $grp->result (...)
657		721
658	Set the result value(s) that will be passed to the group callback when all	722	Set the result value(s) that will be passed to the group callback when all
659	subrequests have finished. By default, no argument will be passed.	723	subrequests have finished. By default, no argument will be passed.
660		724
661	=item $grp->set_feeder ($callback->($grp))	725	=item feed $grp $callback->($grp)
662
663	[VERY EXPERIMENTAL]
664		726
665	Sets a feeder/generator on this group: every group can have an attached	727	Sets a feeder/generator on this group: every group can have an attached
666	generator that generates requests if idle. The idea behind this is that,	728	generator that generates requests if idle. The idea behind this is that,
667	although you could just queue as many requests as you want in a group,	729	although you could just queue as many requests as you want in a group,
668	this might starve other requests for a potentially long time. For	730	this might starve other requests for a potentially long time. For
669	example, C<aio_scandir> might generate hundreds of thousands C<aio_stat>	731	example, C<aio_scandir> might generate hundreds of thousands C<aio_stat>
670	requests, delaying any later requests for a long time.	732	requests, delaying any later requests for a long time.
671		733
672	To avoid this, and allow incremental generation of requests, you can	734	To avoid this, and allow incremental generation of requests, you can
673	instead a group and set a feeder on it that generates those requests. The	735	instead a group and set a feeder on it that generates those requests. The
674	feeder will be called whenever there are few enough (see C<feeder_limit>,	736	feed callback will be called whenever there are few enough (see C<limit>,
675	below) requests active in the group itself and is expected to queue more	737	below) requests active in the group itself and is expected to queue more
676	requests.	738	requests.
677		739
678	The feeder can queue as many requests as it likes (i.e. C<add> does not	740	The feed callback can queue as many requests as it likes (i.e. C<add> does
679	impose any limits).	741	not impose any limits).
680		742
681	If the feeder does not queue more requests when called, it will be	743	If the feed does not queue more requests when called, it will be
682	automatically removed from the group.	744	automatically removed from the group.
683		745
684	If the feeder limit is C<0>, it will be set to C<2> automatically.	746	If the feed limit is C<0>, it will be set to C<2> automatically.
685		747
686	Example:	748	Example:
687		749
688	# stat all files in @files, but only ever use four aio requests concurrently:	750	# stat all files in @files, but only ever use four aio requests concurrently:
689		751
690	my $grp = aio_group sub { print "finished\n" };	752	my $grp = aio_group sub { print "finished\n" };
691	$grp->feeder_limit (4);	753	limit $grp 4;
692	$grp->set_feeder (sub {	754	feed $grp sub {
693	my $file = pop @files	755	my $file = pop @files
694	or return;	756	or return;
695		757
696	add $grp aio_stat $file, sub { ... };	758	add $grp aio_stat $file, sub { ... };
697	});	759	};
698		760
699	=item $grp->feeder_limit ($num)	761	=item limit $grp $num
700		762
701	Sets the feeder limit for the group: The feeder will be called whenever	763	Sets the feeder limit for the group: The feeder will be called whenever
702	the group contains less than this many requests.	764	the group contains less than this many requests.
703		765
704	Setting the limit to C<0> will pause the feeding process.	766	Setting the limit to C<0> will pause the feeding process.
…		…
850	This module should do "the right thing" when the process using it forks:	912	This module should do "the right thing" when the process using it forks:
851		913
852	Before the fork, IO::AIO enters a quiescent state where no requests	914	Before the fork, IO::AIO enters a quiescent state where no requests
853	can be added in other threads and no results will be processed. After	915	can be added in other threads and no results will be processed. After
854	the fork the parent simply leaves the quiescent state and continues	916	the fork the parent simply leaves the quiescent state and continues
855	request/result processing, while the child clears the request/result	917	request/result processing, while the child frees the request/result queue
856	queue (so the requests started before the fork will only be handled in	918	(so that the requests started before the fork will only be handled in the
857	the parent). Threads will be started on demand until the limit ste in the	919	parent). Threads will be started on demand until the limit set in the
858	parent process has been reached again.	920	parent process has been reached again.
859		921
860	In short: the parent will, after a short pause, continue as if fork had	922	In short: the parent will, after a short pause, continue as if fork had
861	not been called, while the child will act as if IO::AIO has not been used	923	not been called, while the child will act as if IO::AIO has not been used
862	yet.	924	yet.
863		925
864	=head2 MEMORY USAGE	926	=head2 MEMORY USAGE
865		927
		928	Per-request usage:
		929
866	Each aio request uses - depending on your architecture - around 128 bytes	930	Each aio request uses - depending on your architecture - around 100-200
867	of memory. In addition, stat requests need a stat buffer (possibly a few	931	bytes of memory. In addition, stat requests need a stat buffer (possibly
868	hundred bytes). Perl scalars and other data passed into aio requests will	932	a few hundred bytes), readdir requires a result buffer and so on. Perl
869	also be locked.	933	scalars and other data passed into aio requests will also be locked and
		934	will consume memory till the request has entered the done state.
870		935
871	This is now awfully much, so queuing lots of requests is not usually a	936	This is now awfully much, so queuing lots of requests is not usually a
872	problem.	937	problem.
873		938
874	Each thread needs a stack area which is usually around 16k, sometimes much	939	Per-thread usage:
875	larger, depending on the OS.	940
		941	In the execution phase, some aio requests require more memory for
		942	temporary buffers, and each thread requires a stack and other data
		943	structures (usually around 16k-128k, depending on the OS).
		944
		945	=head1 KNOWN BUGS
		946
		947	Known bugs will be fixed in the next release.
876		948
877	=head1 SEE ALSO	949	=head1 SEE ALSO
878		950
879	L<Coro>, L<Linux::AIO> (obsolete).	951	L<Coro::AIO>.
880		952
881	=head1 AUTHOR	953	=head1 AUTHOR
882		954
883	Marc Lehmann <schmorp@schmorp.de>	955	Marc Lehmann <schmorp@schmorp.de>
884	http://home.schmorp.de/	956	http://home.schmorp.de/

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Comparing IO-AIO/AIO.pm (file contents): Revision 1.63 by root, Mon Oct 23 00:34:36 2006 UTC vs. Revision 1.75 by root, Tue Oct 24 20:10:26 2006 UTC

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Comparing IO-AIO/AIO.pm (file contents):
Revision 1.63 by root, Mon Oct 23 00:34:36 2006 UTC vs.
Revision 1.75 by root, Tue Oct 24 20:10:26 2006 UTC