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

Comparing IO-AIO/AIO.pm (file contents):
Revision 1.56 by root, Sun Oct 22 00:53:47 2006 UTC vs.
Revision 1.78 by root, Thu Oct 26 12:38:04 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);	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
…		…
201	=cut	283	=cut
202		284
203	sub aio_move($$$) {	285	sub aio_move($$$) {
204	my ($src, $dst, $cb) = @_;	286	my ($src, $dst, $cb) = @_;
205		287
206	my $grp = aio_group;	288	my $grp = aio_group $cb;
207		289
208	add $grp aio_rename $src, $dst, sub {	290	add $grp aio_rename $src, $dst, sub {
209	if ($_[0] && $! == EXDEV) {	291	if ($_[0] && $! == EXDEV) {
210	add $grp aio_open $src, O_RDONLY, 0, sub {	292	add $grp aio_open $src, O_RDONLY, 0, sub {
211	if (my $src_fh = $_[0]) {	293	if (my $src_fh = $_[0]) {
…		…
221	chmod $stat[2] & 07777, $dst_fh;	303	chmod $stat[2] & 07777, $dst_fh;
222	chown $stat[4], $stat[5], $dst_fh;	304	chown $stat[4], $stat[5], $dst_fh;
223	close $dst_fh;	305	close $dst_fh;
224		306
225	add $grp aio_unlink $src, sub {	307	add $grp aio_unlink $src, sub {
226	$cb->($_[0]);	308	$grp->result ($_[0]);
227	};	309	};
228	} else {	310	} else {
229	my $errno = $!;	311	my $errno = $!;
230	add $grp aio_unlink $dst, sub {	312	add $grp aio_unlink $dst, sub {
231	$! = $errno;	313	$! = $errno;
232	$cb->(-1);	314	$grp->result (-1);
233	};	315	};
234	}	316	}
235	};	317	};
236	} else {	318	} else {
237	$cb->(-1);	319	$grp->result (-1);
238	}	320	}
239	},	321	},
240		322
241	} else {	323	} else {
242	$cb->(-1);	324	$grp->result (-1);
243	}	325	}
244	};	326	};
245	} else {	327	} else {
246	$cb->($_[0]);	328	$grp->result ($_[0]);
247	}	329	}
248	};	330	};
249		331
250	$grp	332	$grp
251	}	333	}
…		…
344	with the filenames.	426	with the filenames.
345		427
346	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	428	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
347		429
348	Scans a directory (similar to C<aio_readdir>) but additionally tries to	430	Scans a directory (similar to C<aio_readdir>) but additionally tries to
349	separate the entries of directory C<$path> into two sets of names, ones	431	efficiently separate the entries of directory C<$path> into two sets of
350	you can recurse into (directories or links to them), and ones you cannot	432	names, directories you can recurse into (directories), and ones you cannot
351	recurse into (everything else).	433	recurse into (everything else, including symlinks to directories).
352		434
353	C<aio_scandir> is a composite request that consists of many sub	435	C<aio_scandir> is a composite request that creates of many sub requests_
354	requests. C<$maxreq> specifies the maximum number of outstanding aio	436	C<$maxreq> specifies the maximum number of outstanding aio requests that
355	requests that this function generates. If it is C<< <= 0 >>, then a	437	this function generates. If it is C<< <= 0 >>, then a suitable default
356	suitable default will be chosen (currently 8).	438	will be chosen (currently 6).
357		439
358	On error, the callback is called without arguments, otherwise it receives	440	On error, the callback is called without arguments, otherwise it receives
359	two array-refs with path-relative entry names.	441	two array-refs with path-relative entry names.
360		442
361	Example:	443	Example:
…		…
398	=cut	480	=cut
399		481
400	sub aio_scandir($$$) {	482	sub aio_scandir($$$) {
401	my ($path, $maxreq, $cb) = @_;	483	my ($path, $maxreq, $cb) = @_;
402		484
403	my $grp = aio_group;	485	my $grp = aio_group $cb;
404		486
405	$maxreq = 8 if $maxreq <= 0;	487	$maxreq = 6 if $maxreq <= 0;
406		488
407	# stat once	489	# stat once
408	add $grp aio_stat $path, sub {	490	add $grp aio_stat $path, sub {
409	return $cb->() if $_[0];	491	return $grp->result () if $_[0];
410	my $now = time;	492	my $now = time;
411	my $hash1 = join ":", (stat _)[0,1,3,7,9];	493	my $hash1 = join ":", (stat _)[0,1,3,7,9];
412		494
413	# read the directory entries	495	# read the directory entries
414	add $grp aio_readdir $path, sub {	496	add $grp aio_readdir $path, sub {
415	my $entries = shift	497	my $entries = shift
416	or return $cb->();	498	or return $grp->result ();
417		499
418	# stat the dir another time	500	# stat the dir another time
419	add $grp aio_stat $path, sub {	501	add $grp aio_stat $path, sub {
420	my $hash2 = join ":", (stat _)[0,1,3,7,9];	502	my $hash2 = join ":", (stat _)[0,1,3,7,9];
421		503
…		…
426	$ndirs = -1;	508	$ndirs = -1;
427	} else {	509	} else {
428	# if nlink == 2, we are finished	510	# if nlink == 2, we are finished
429	# on non-posix-fs's, we rely on nlink < 2	511	# on non-posix-fs's, we rely on nlink < 2
430	$ndirs = (stat _)[3] - 2	512	$ndirs = (stat _)[3] - 2
431	or return $cb->([], $entries);	513	or return $grp->result ([], $entries);
432	}	514	}
433		515
434	# sort into likely dirs and likely nondirs	516	# sort into likely dirs and likely nondirs
435	# dirs == files without ".", short entries first	517	# dirs == files without ".", short entries first
436	$entries = [map $_->[0],	518	$entries = [map $_->[0],
…		…
438	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],	520	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
439	@$entries];	521	@$entries];
440		522
441	my (@dirs, @nondirs);	523	my (@dirs, @nondirs);
442		524
443	my ($statcb, $schedcb);	525	my $statgrp = add $grp aio_group sub {
444	my $nreq = 0;	526	$grp->result (\@dirs, \@nondirs);
		527	};
445		528
446	$schedcb = sub {	529	limit $statgrp $maxreq;
447	if (@$entries) {	530	feed $statgrp sub {
448	if ($nreq < $maxreq) {	531	return unless @$entries;
449	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	}
450	$nreq++;	550	}
451	add $grp aio_stat "$path/$ent/.", sub { $statcb->($_[0], $ent) };
452	}	551	}
453	} elsif (!$nreq) {
454	# finished
455	undef $statcb;
456	undef $schedcb;
457	$cb->(\@dirs, \@nondirs) if $cb;
458	undef $cb;
459	}	552	};
460	};	553	};
461	$statcb = sub {
462	my ($status, $entry) = @_;
463
464	if ($status < 0) {
465	$nreq--;
466	push @nondirs, $entry;
467	&$schedcb;
468	} else {
469	# need to check for real directory
470	add $grp aio_lstat "$path/$entry", sub {
471	$nreq--;
472
473	if (-d _) {
474	push @dirs, $entry;
475
476	if (!--$ndirs) {
477	push @nondirs, @$entries;
478	$entries = [];
479	}
480	} else {
481	push @nondirs, $entry;
482	}
483
484	&$schedcb;
485	}
486	}
487	};
488
489	&$schedcb while @$entries && $nreq < $maxreq;
490	};	554	};
491	};	555	};
492	};	556	};
493		557
494	$grp	558	$grp
…		…
505	callback with the fdatasync result code.	569	callback with the fdatasync result code.
506		570
507	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
508	detected, it will be emulated by calling C<fsync> instead.	572	detected, it will be emulated by calling C<fsync> instead.
509		573
510	=item aio_group $callback->()	574	=item aio_group $callback->(...)
511
512	[EXPERIMENTAL]
513		575
514	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
515	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
516	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.
517		580
518	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
519	for more info.	582	for more info.
520		583
521	Example:	584	Example:
…		…
527	add $grp	590	add $grp
528	(aio_stat ...),	591	(aio_stat ...),
529	(aio_stat ...),	592	(aio_stat ...),
530	...;	593	...;
531		594
		595	=item aio_nop $callback->()
		596
		597	This is a special request - it does nothing in itself and is only used for
		598	side effects, such as when you want to add a dummy request to a group so
		599	that finishing the requests in the group depends on executing the given
		600	code.
		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
532	=item IO::AIO::aio_sleep $fractional_seconds, $callback->() NOT EXPORTED	608	=item IO::AIO::aio_busy $fractional_seconds, $callback->() NOT EXPORTED
533		609
534	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
535	the request workers to sleep for the given time.	611	the request workers to sleep for the given time.
536		612
537	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
538	like sleep and file handle readable/writable, the overhead this creates	614	like sleep and file handle readable/writable, the overhead this creates is
539	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
540	under artificial I/O pressure.	616	except to put your application under artificial I/O pressure.
541		617
542	=back	618	=back
543		619
544	=head2 IO::AIO::REQ CLASS	620	=head2 IO::AIO::REQ CLASS
545		621
546	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
547	called in non-void context.	623	called in non-void context.
548		624
549	A request always moves through the following five states in its lifetime,
550	in order: B<ready> (request has been created, but has not been executed
551	yet), B<execute> (request is currently being executed), B<pending>
552	(request has been executed but callback has not been called yet),
553	B<result> (results are being processed synchronously, includes calling the
554	callback) and B<done> (request has reached the end of its lifetime and
555	holds no resources anymore).
556
557	=over 4	625	=over 4
558		626
559	=item $req->cancel	627	=item cancel $req
560		628
561	Cancels the request, if possible. Has the effect of skipping execution	629	Cancels the request, if possible. Has the effect of skipping execution
562	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
563	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
564	untouched. That means that requests that currently execute will not be	632	untouched. That means that requests that currently execute will not be
565	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.
566		634
		635	=item cb $req $callback->(...)
		636
		637	Replace (or simply set) the callback registered to the request.
		638
567	=back	639	=back
568		640
569	=head2 IO::AIO::GRP CLASS	641	=head2 IO::AIO::GRP CLASS
570		642
571	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
…		…
585	You add requests by calling the C<add> method with one or more	657	You add requests by calling the C<add> method with one or more
586	C<IO::AIO::REQ> objects:	658	C<IO::AIO::REQ> objects:
587		659
588	$grp->add (aio_unlink "...");	660	$grp->add (aio_unlink "...");
589		661
590	add $grp aio_stat "...", sub { ... };	662	add $grp aio_stat "...", sub {
		663	$_[0] or return $grp->result ("error");
		664
		665	# add another request dynamically, if first succeeded
		666	add $grp aio_open "...", sub {
		667	$grp->result ("ok");
		668	};
		669	};
591		670
592	This makes it very easy to create composite requests (see the source of	671	This makes it very easy to create composite requests (see the source of
593	C<aio_move> for an application) that work and feel like simple requests.	672	C<aio_move> for an application) that work and feel like simple requests.
594		673
		674	=over 4
		675
595	The IO::AIO::GRP objects will be cleaned up during calls to	676	=item * The IO::AIO::GRP objects will be cleaned up during calls to
596	C<IO::AIO::poll_cb>, just like any other request.	677	C<IO::AIO::poll_cb>, just like any other request.
597		678
598	They can be canceled like any other request. Canceling will cancel not	679	=item * They can be canceled like any other request. Canceling will cancel not
599	just the request itself, but also all requests it contains.	680	only the request itself, but also all requests it contains.
600		681
601	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.
		683
		684	=item * You must not add requests to a group from within the group callback (or
		685	any later time).
		686
		687	=back
602		688
603	Their lifetime, simplified, looks like this: when they are empty, they	689	Their lifetime, simplified, looks like this: when they are empty, they
604	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
605	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
606	exist.	692	exist.
607		693
		694	That means after creating a group you have some time to add requests. And
		695	in the callbacks of those requests, you can add further requests to the
		696	group. And only when all those requests have finished will the the group
		697	itself finish.
		698
608	=over 4	699	=over 4
609		700
		701	=item add $grp ...
		702
610	=item $grp->add (...)	703	=item $grp->add (...)
611		704
612	=item add $grp ...	705	Add one or more requests to the group. Any type of L<IO::AIO::REQ> can
		706	be added, including other groups, as long as you do not create circular
		707	dependencies.
613		708
614	Add one or more	709	Returns all its arguments.
615	Cancels the request, if possible. Has the effect of skipping execution	710
616	when entering the B<execute> state and skipping calling the callback when	711	=item $grp->cancel_subs
617	entering the the B<result> state, but will leave the request otherwise	712
618	untouched. That means that requests that currently execute will not be	713	Cancel all subrequests and clears any feeder, but not the group request
619	stopped and resources held by the request will not be freed prematurely.	714	itself. Useful when you queued a lot of events but got a result early.
		715
		716	=item $grp->result (...)
		717
		718	Set the result value(s) that will be passed to the group callback when all
		719	subrequests have finished. By default, no argument will be passed.
		720
		721	=item feed $grp $callback->($grp)
		722
		723	Sets a feeder/generator on this group: every group can have an attached
		724	generator that generates requests if idle. The idea behind this is that,
		725	although you could just queue as many requests as you want in a group,
		726	this might starve other requests for a potentially long time. For
		727	example, C<aio_scandir> might generate hundreds of thousands C<aio_stat>
		728	requests, delaying any later requests for a long time.
		729
		730	To avoid this, and allow incremental generation of requests, you can
		731	instead a group and set a feeder on it that generates those requests. The
		732	feed callback will be called whenever there are few enough (see C<limit>,
		733	below) requests active in the group itself and is expected to queue more
		734	requests.
		735
		736	The feed callback can queue as many requests as it likes (i.e. C<add> does
		737	not impose any limits).
		738
		739	If the feed does not queue more requests when called, it will be
		740	automatically removed from the group.
		741
		742	If the feed limit is C<0>, it will be set to C<2> automatically.
		743
		744	Example:
		745
		746	# stat all files in @files, but only ever use four aio requests concurrently:
		747
		748	my $grp = aio_group sub { print "finished\n" };
		749	limit $grp 4;
		750	feed $grp sub {
		751	my $file = pop @files
		752	or return;
		753
		754	add $grp aio_stat $file, sub { ... };
		755	};
		756
		757	=item limit $grp $num
		758
		759	Sets the feeder limit for the group: The feeder will be called whenever
		760	the group contains less than this many requests.
		761
		762	Setting the limit to C<0> will pause the feeding process.
620		763
621	=back	764	=back
622		765
623	=head2 SUPPORT FUNCTIONS	766	=head2 SUPPORT FUNCTIONS
624		767
…		…
637		780
638	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
639	regularly. Returns the number of events processed. Returns immediately	782	regularly. Returns the number of events processed. Returns immediately
640	when no events are outstanding.	783	when no events are outstanding.
641		784
		785	If not all requests were processed for whatever reason, the filehandle
		786	will still be ready when C<poll_cb> returns.
		787
642	Example: Install an Event watcher that automatically calls	788	Example: Install an Event watcher that automatically calls
643	IO::AIO::poll_cb with high priority:	789	IO::AIO::poll_cb with high priority:
644		790
645	Event->io (fd => IO::AIO::poll_fileno,	791	Event->io (fd => IO::AIO::poll_fileno,
646	poll => 'r', async => 1,	792	poll => 'r', async => 1,
647	cb => \&IO::AIO::poll_cb);	793	cb => \&IO::AIO::poll_cb);
648		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 });
		810
649	=item IO::AIO::poll_wait	811	=item IO::AIO::poll_wait
650		812
651	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
652	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
653	for some requests to finish).	815	for some requests to finish).
…		…
682	IO::AIO::poll_wait, IO::AIO::poll_cb	844	IO::AIO::poll_wait, IO::AIO::poll_cb
683	if IO::AIO::nreqs;	845	if IO::AIO::nreqs;
684		846
685	=item IO::AIO::min_parallel $nthreads	847	=item IO::AIO::min_parallel $nthreads
686		848
687	Set the minimum number of AIO threads to C<$nthreads>. The current default	849	Set the minimum number of AIO threads to C<$nthreads>. The current
688	is C<4>, which means four asynchronous operations can be done at one time	850	default is C<8>, which means eight asynchronous operations can execute
689	(the number of outstanding operations, however, is unlimited).	851	concurrently at any one time (the number of outstanding requests,
		852	however, is unlimited).
690		853
691	IO::AIO starts threads only on demand, when an AIO request is queued and	854	IO::AIO starts threads only on demand, when an AIO request is queued and
692	no free thread exists.	855	no free thread exists.
693		856
694	It is recommended to keep the number of threads low, as some Linux	857	It is recommended to keep the number of threads relatively low, as some
695	kernel versions will scale negatively with the number of threads (higher	858	Linux kernel versions will scale negatively with the number of threads
696	parallelity => MUCH higher latency). With current Linux 2.6 versions, 4-32	859	(higher parallelity => MUCH higher latency). With current Linux 2.6
697	threads should be fine.	860	versions, 4-32 threads should be fine.
698		861
699	Under most circumstances you don't need to call this function, as the	862	Under most circumstances you don't need to call this function, as the
700	module selects a default that is suitable for low to moderate load.	863	module selects a default that is suitable for low to moderate load.
701		864
702	=item IO::AIO::max_parallel $nthreads	865	=item IO::AIO::max_parallel $nthreads
…		…
713		876
714	Under normal circumstances you don't need to call this function.	877	Under normal circumstances you don't need to call this function.
715		878
716	=item $oldnreqs = IO::AIO::max_outstanding $nreqs	879	=item $oldnreqs = IO::AIO::max_outstanding $nreqs
717		880
		881	[REMOVED]
		882
		883	Pre-2.x versions used max_outstanding for a crude request queue length limit.
		884
		885	In 2.x+ you are advised to use a group and a feeder to limit
		886	concurrency. The max_outstanding feature ran very unstable (endless
		887	recursions causing segfaults, bad interaction with groups etc.) and was
		888	removed.
		889
		890	I am deeply sorry, but I am still on the hunt for a good limiting interface.
		891
		892	Original description was as follows:
		893
718	Sets the maximum number of outstanding requests to C<$nreqs>. If you	894	Sets the maximum number of outstanding requests to C<$nreqs>. If you try
719	try to queue up more than this number of requests, the caller will block until	895	to queue up more than this number of requests, the caller will block until
720	some requests have been handled.	896	some requests have been handled.
721
722	The default is very large, so normally there is no practical limit. If you
723	queue up many requests in a loop it often improves speed if you set
724	this to a relatively low number, such as C<100>.
725
726	Under normal circumstances you don't need to call this function.
727		897
728	=back	898	=back
729		899
730	=cut	900	=cut
731		901
…		…
743	or return undef;	913	or return undef;
744		914
745	*$sym	915	*$sym
746	}	916	}
747		917
748	min_parallel 4;	918	min_parallel 8;
749		919
750	END {	920	END {
751	max_parallel 0;	921	max_parallel 0;
752	}	922	}
753		923
…		…
758	This module should do "the right thing" when the process using it forks:	928	This module should do "the right thing" when the process using it forks:
759		929
760	Before the fork, IO::AIO enters a quiescent state where no requests	930	Before the fork, IO::AIO enters a quiescent state where no requests
761	can be added in other threads and no results will be processed. After	931	can be added in other threads and no results will be processed. After
762	the fork the parent simply leaves the quiescent state and continues	932	the fork the parent simply leaves the quiescent state and continues
763	request/result processing, while the child clears the request/result	933	request/result processing, while the child frees the request/result queue
764	queue (so the requests started before the fork will only be handled in	934	(so that the requests started before the fork will only be handled in the
765	the parent). Threads will be started on demand until the limit ste in the	935	parent). Threads will be started on demand until the limit set in the
766	parent process has been reached again.	936	parent process has been reached again.
767		937
768	In short: the parent will, after a short pause, continue as if fork had	938	In short: the parent will, after a short pause, continue as if fork had
769	not been called, while the child will act as if IO::AIO has not been used	939	not been called, while the child will act as if IO::AIO has not been used
770	yet.	940	yet.
771		941
		942	=head2 MEMORY USAGE
		943
		944	Per-request usage:
		945
		946	Each aio request uses - depending on your architecture - around 100-200
		947	bytes of memory. In addition, stat requests need a stat buffer (possibly
		948	a few hundred bytes), readdir requires a result buffer and so on. Perl
		949	scalars and other data passed into aio requests will also be locked and
		950	will consume memory till the request has entered the done state.
		951
		952	This is now awfully much, so queuing lots of requests is not usually a
		953	problem.
		954
		955	Per-thread usage:
		956
		957	In the execution phase, some aio requests require more memory for
		958	temporary buffers, and each thread requires a stack and other data
		959	structures (usually around 16k-128k, depending on the OS).
		960
		961	=head1 KNOWN BUGS
		962
		963	Known bugs will be fixed in the next release.
		964
772	=head1 SEE ALSO	965	=head1 SEE ALSO
773		966
774	L<Coro>, L<Linux::AIO> (obsolete).	967	L<Coro::AIO>.
775		968
776	=head1 AUTHOR	969	=head1 AUTHOR
777		970
778	Marc Lehmann <schmorp@schmorp.de>	971	Marc Lehmann <schmorp@schmorp.de>
779	http://home.schmorp.de/	972	http://home.schmorp.de/

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Comparing IO-AIO/AIO.pm (file contents): Revision 1.56 by root, Sun Oct 22 00:53:47 2006 UTC vs. Revision 1.78 by root, Thu Oct 26 12:38:04 2006 UTC

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Comparing IO-AIO/AIO.pm (file contents):
Revision 1.56 by root, Sun Oct 22 00:53:47 2006 UTC vs.
Revision 1.78 by root, Thu Oct 26 12:38:04 2006 UTC