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

Comparing IO-AIO/AIO.pm (file contents):
Revision 1.64 by root, Mon Oct 23 00:50:10 2006 UTC vs.
Revision 1.72 by root, Tue Oct 24 14:25:53 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
…		…
344		424
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, $nondirs)
349
350	[EXPERIMENTAL due to internal aio_group use]
351		429
352	Scans a directory (similar to C<aio_readdir>) but additionally tries to	430	Scans a directory (similar to C<aio_readdir>) but additionally tries to
353	separate the entries of directory C<$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).
…		…
517		595
518	[EXPERIMENTAL]	596	[EXPERIMENTAL]
519		597
520	This is a very special aio request: Instead of doing something, it is a	598	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	599	container for other aio requests, which is useful if you want to bundle
522	many requests into a single, composite, request.	600	many requests into a single, composite, request with a definite callback
		601	and the ability to cancel the whole request with its subrequests.
523		602
524	Returns an object of class L<IO::AIO::GRP>. See its documentation below	603	Returns an object of class L<IO::AIO::GRP>. See its documentation below
525	for more info.	604	for more info.
526		605
527	Example:	606	Example:
…		…
546	phase and still requires a worker thread. Thus, the callback will not	625	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	626	be executed immediately but only after other requests in the queue have
548	entered their execution phase. This can be used to measure request	627	entered their execution phase. This can be used to measure request
549	latency.	628	latency.
550		629
551	=item IO::AIO::aio_sleep $fractional_seconds, $callback->() NOT EXPORTED	630	=item IO::AIO::aio_busy $fractional_seconds, $callback->() NOT EXPORTED
552		631
553	Mainly used for debugging and benchmarking, this aio request puts one of	632	Mainly used for debugging and benchmarking, this aio request puts one of
554	the request workers to sleep for the given time.	633	the request workers to sleep for the given time.
555		634
556	While it is theoretically handy to have simple I/O scheduling requests	635	While it is theoretically handy to have simple I/O scheduling requests
557	like sleep and file handle readable/writable, the overhead this creates	636	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	637	immense (it blocks a thread for a long time) so do not use this function
559	under artificial I/O pressure.	638	except to put your application under artificial I/O pressure.
560		639
561	=back	640	=back
562		641
563	=head2 IO::AIO::REQ CLASS	642	=head2 IO::AIO::REQ CLASS
564		643
565	All non-aggregate C<aio_*> functions return an object of this class when	644	All non-aggregate C<aio_*> functions return an object of this class when
566	called in non-void context.	645	called in non-void context.
567		646
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
576	=over 4	647	=over 4
577		648
578	=item $req->cancel	649	=item cancel $req
579		650
580	Cancels the request, if possible. Has the effect of skipping execution	651	Cancels the request, if possible. Has the effect of skipping execution
581	when entering the B<execute> state and skipping calling the callback when	652	when entering the B<execute> state and skipping calling the callback when
582	entering the the B<result> state, but will leave the request otherwise	653	entering the the B<result> state, but will leave the request otherwise
583	untouched. That means that requests that currently execute will not be	654	untouched. That means that requests that currently execute will not be
584	stopped and resources held by the request will not be freed prematurely.	655	stopped and resources held by the request will not be freed prematurely.
585		656
		657	=item cb $req $callback->(...)
		658
		659	Replace (or simply set) the callback registered to the request.
		660
586	=back	661	=back
587		662
588	=head2 IO::AIO::GRP CLASS	663	=head2 IO::AIO::GRP CLASS
589		664
590	This class is a subclass of L<IO::AIO::REQ>, so all its methods apply to	665	This class is a subclass of L<IO::AIO::REQ>, so all its methods apply to
…		…
647	group. And only when all those requests have finished will the the group	722	group. And only when all those requests have finished will the the group
648	itself finish.	723	itself finish.
649		724
650	=over 4	725	=over 4
651		726
		727	=item add $grp ...
		728
652	=item $grp->add (...)	729	=item $grp->add (...)
653
654	=item add $grp ...
655		730
656	Add one or more requests to the group. Any type of L<IO::AIO::REQ> can	731	Add one or more requests to the group. Any type of L<IO::AIO::REQ> can
657	be added, including other groups, as long as you do not create circular	732	be added, including other groups, as long as you do not create circular
658	dependencies.	733	dependencies.
659		734
…		…
662	=item $grp->result (...)	737	=item $grp->result (...)
663		738
664	Set the result value(s) that will be passed to the group callback when all	739	Set the result value(s) that will be passed to the group callback when all
665	subrequests have finished. By default, no argument will be passed.	740	subrequests have finished. By default, no argument will be passed.
666		741
667	=item $grp->set_feeder ($callback->($grp))	742	=item feed $grp $callback->($grp)
668		743
669	[VERY EXPERIMENTAL]	744	[VERY EXPERIMENTAL]
670		745
671	Sets a feeder/generator on this group: every group can have an attached	746	Sets a feeder/generator on this group: every group can have an attached
672	generator that generates requests if idle. The idea behind this is that,	747	generator that generates requests if idle. The idea behind this is that,
…		…
675	example, C<aio_scandir> might generate hundreds of thousands C<aio_stat>	750	example, C<aio_scandir> might generate hundreds of thousands C<aio_stat>
676	requests, delaying any later requests for a long time.	751	requests, delaying any later requests for a long time.
677		752
678	To avoid this, and allow incremental generation of requests, you can	753	To avoid this, and allow incremental generation of requests, you can
679	instead a group and set a feeder on it that generates those requests. The	754	instead a group and set a feeder on it that generates those requests. The
680	feeder will be called whenever there are few enough (see C<feeder_limit>,	755	feed callback will be called whenever there are few enough (see C<limit>,
681	below) requests active in the group itself and is expected to queue more	756	below) requests active in the group itself and is expected to queue more
682	requests.	757	requests.
683		758
684	The feeder can queue as many requests as it likes (i.e. C<add> does not	759	The feed callback can queue as many requests as it likes (i.e. C<add> does
685	impose any limits).	760	not impose any limits).
686		761
687	If the feeder does not queue more requests when called, it will be	762	If the feed does not queue more requests when called, it will be
688	automatically removed from the group.	763	automatically removed from the group.
689		764
690	If the feeder limit is C<0>, it will be set to C<2> automatically.	765	If the feed limit is C<0>, it will be set to C<2> automatically.
691		766
692	Example:	767	Example:
693		768
694	# stat all files in @files, but only ever use four aio requests concurrently:	769	# stat all files in @files, but only ever use four aio requests concurrently:
695		770
696	my $grp = aio_group sub { print "finished\n" };	771	my $grp = aio_group sub { print "finished\n" };
697	$grp->feeder_limit (4);	772	limit $grp 4;
698	$grp->set_feeder (sub {	773	feed $grp sub {
699	my $file = pop @files	774	my $file = pop @files
700	or return;	775	or return;
701		776
702	add $grp aio_stat $file, sub { ... };	777	add $grp aio_stat $file, sub { ... };
703	});	778	};
704		779
705	=item $grp->feeder_limit ($num)	780	=item limit $grp $num
706		781
707	Sets the feeder limit for the group: The feeder will be called whenever	782	Sets the feeder limit for the group: The feeder will be called whenever
708	the group contains less than this many requests.	783	the group contains less than this many requests.
709		784
710	Setting the limit to C<0> will pause the feeding process.	785	Setting the limit to C<0> will pause the feeding process.
…		…
856	This module should do "the right thing" when the process using it forks:	931	This module should do "the right thing" when the process using it forks:
857		932
858	Before the fork, IO::AIO enters a quiescent state where no requests	933	Before the fork, IO::AIO enters a quiescent state where no requests
859	can be added in other threads and no results will be processed. After	934	can be added in other threads and no results will be processed. After
860	the fork the parent simply leaves the quiescent state and continues	935	the fork the parent simply leaves the quiescent state and continues
861	request/result processing, while the child clears the request/result	936	request/result processing, while the child frees the request/result queue
862	queue (so the requests started before the fork will only be handled in	937	(so that the requests started before the fork will only be handled in the
863	the parent). Threads will be started on demand until the limit ste in the	938	parent). Threads will be started on demand until the limit set in the
864	parent process has been reached again.	939	parent process has been reached again.
		940
		941	Temporary memory that was allocated for request processing is not
		942	reclaimed in the child, however. While this is possible in some cases, it
		943	is almost impossible in others (threads are evil you know), so you will
		944	have to live with it. This is around 64k buffer (for sendfile, readahead
		945	emulation) + the size of the directory being scanned (readdir).
865		946
866	In short: the parent will, after a short pause, continue as if fork had	947	In short: the parent will, after a short pause, continue as if fork had
867	not been called, while the child will act as if IO::AIO has not been used	948	not been called, while the child will act as if IO::AIO has not been used
868	yet.	949	yet.
869		950
870	=head2 MEMORY USAGE	951	=head2 MEMORY USAGE
871		952
		953	Per-request usage:
		954
872	Each aio request uses - depending on your architecture - around 128 bytes	955	Each aio request uses - depending on your architecture - around 100-200
873	of memory. In addition, stat requests need a stat buffer (possibly a few	956	bytes of memory. In addition, stat requests need a stat buffer (possibly
874	hundred bytes). Perl scalars and other data passed into aio requests will	957	a few hundred bytes), readdir requires a result buffer and so on. Perl
875	also be locked.	958	scalars and other data passed into aio requests will also be locked and
		959	will consume memory till the request has entered the done state.
876		960
877	This is now awfully much, so queuing lots of requests is not usually a	961	This is now awfully much, so queuing lots of requests is not usually a
878	problem.	962	problem.
879		963
880	Each thread needs a stack area which is usually around 16k, sometimes much	964	Per-thread usage:
881	larger, depending on the OS.	965
		966	In the execution phase, some aio requests require more memory for
		967	temporary buffers, and each thread requires a stack and other data
		968	structures (usually around 16k-128k, depending on the OS).
		969
		970	=head1 KNOWN BUGS
		971
		972	See FORK BEHAVIOUR, above.
882		973
883	=head1 SEE ALSO	974	=head1 SEE ALSO
884		975
885	L<Coro>, L<Linux::AIO> (obsolete).	976	L<Coro::AIO>.
886		977
887	=head1 AUTHOR	978	=head1 AUTHOR
888		979
889	Marc Lehmann <schmorp@schmorp.de>	980	Marc Lehmann <schmorp@schmorp.de>
890	http://home.schmorp.de/	981	http://home.schmorp.de/

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Comparing IO-AIO/AIO.pm (file contents): Revision 1.64 by root, Mon Oct 23 00:50:10 2006 UTC vs. Revision 1.72 by root, Tue Oct 24 14:25:53 2006 UTC

Diff Legend

Comparing IO-AIO/AIO.pm (file contents):
Revision 1.64 by root, Mon Oct 23 00:50:10 2006 UTC vs.
Revision 1.72 by root, Tue Oct 24 14:25:53 2006 UTC