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

Comparing IO-AIO/AIO.pm (file contents):
Revision 1.70 by root, Tue Oct 24 03:40:38 2006 UTC vs.
Revision 1.81 by root, Fri Oct 27 19:17:23 2006 UTC

…		…
51	=head1 DESCRIPTION	51	=head1 DESCRIPTION
52		52
53	This module implements asynchronous I/O using whatever means your	53	This module implements asynchronous I/O using whatever means your
54	operating system supports.	54	operating system supports.
55		55
56	Currently, a number of threads are started that execute your read/writes	56	In this version, a number of threads are started that execute your
57	and signal their completion. You don't need thread support in perl, and	57	requests and signal their completion. You don't need thread support
58	the threads created by this module will not be visible to perl. In the	58	in perl, and the threads created by this module will not be visible
59	future, this module might make use of the native aio functions available	59	to perl. In the future, this module might make use of the native aio
60	on many operating systems. However, they are often not well-supported	60	functions available on many operating systems. However, they are often
61	(Linux doesn't allow them on normal files currently, for example),	61	not well-supported or restricted (Linux doesn't allow them on normal
62	and they would only support aio_read and aio_write, so the remaining	62	files currently, for example), and they would only support aio_read and
63	functionality would have to be implemented using threads anyway.	63	aio_write, so the remaining functionality would have to be implemented
		64	using threads anyway.
64		65
65	Although the module will work with in the presence of other threads,	66	Although the module will work with in the presence of other (Perl-)
66	it is currently not reentrant in any way, so use appropriate locking	67	threads, it is currently not reentrant in any way, so use appropriate
67	yourself, always call C<poll_cb> from within the same thread, or never	68	locking yourself, always call C<poll_cb> from within the same thread, or
68	call C<poll_cb> (or other C<aio_> functions) recursively.	69	never call C<poll_cb> (or other C<aio_> functions) recursively.
		70
		71	=head1 REQUEST ANATOMY AND LIFETIME
		72
		73	Every C<aio_*> function creates a request. which is a C data structure not
		74	directly visible to Perl.
		75
		76	If called in non-void context, every request function returns a Perl
		77	object representing the request. In void context, nothing is returned,
		78	which saves a bit of memory.
		79
		80	The perl object is a fairly standard ref-to-hash object. The hash contents
		81	are not used by IO::AIO so you are free to store anything you like in it.
		82
		83	During their existance, aio requests travel through the following states,
		84	in order:
		85
		86	=over 4
		87
		88	=item ready
		89
		90	Immediately after a request is created it is put into the ready state,
		91	waiting for a thread to execute it.
		92
		93	=item execute
		94
		95	A thread has accepted the request for processing and is currently
		96	executing it (e.g. blocking in read).
		97
		98	=item pending
		99
		100	The request has been executed and is waiting for result processing.
		101
		102	While request submission and execution is fully asynchronous, result
		103	processing is not and relies on the perl interpreter calling C<poll_cb>
		104	(or another function with the same effect).
		105
		106	=item result
		107
		108	The request results are processed synchronously by C<poll_cb>.
		109
		110	The C<poll_cb> function will process all outstanding aio requests by
		111	calling their callbacks, freeing memory associated with them and managing
		112	any groups they are contained in.
		113
		114	=item done
		115
		116	Request has reached the end of its lifetime and holds no resources anymore
		117	(except possibly for the Perl object, but its connection to the actual
		118	aio request is severed and calling its methods will either do nothing or
		119	result in a runtime error).
69		120
70	=cut	121	=cut
71		122
72	package IO::AIO;	123	package IO::AIO;
73		124
…		…
83	aio_lstat aio_unlink aio_rmdir aio_readdir aio_scandir aio_symlink	134	aio_lstat aio_unlink aio_rmdir aio_readdir aio_scandir aio_symlink
84	aio_fsync aio_fdatasync aio_readahead aio_rename aio_link aio_move	135	aio_fsync aio_fdatasync aio_readahead aio_rename aio_link aio_move
85	aio_group aio_nop);	136	aio_group aio_nop);
86	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));	137	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
87	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush	138	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
88	min_parallel max_parallel max_outstanding nreqs);	139	min_parallel max_parallel nreqs nready npending);
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);
…		…
124	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)
125	use something else.	176	use something else.
126		177
127	=over 4	178	=over 4
128		179
129	=item aioreq_pri $pri	180	=item $prev_pri = aioreq_pri [$pri]
130		181
131	Sets the priority for the next aio request. The default priority	182	Returns the priority value that would be used for the next request and, if
		183	C<$pri> is given, sets the priority for the next aio request.
		184
132	is C<0>, the minimum and maximum priorities are C<-4> and C<4>,	185	The default priority is C<0>, the minimum and maximum priorities are C<-4>
133	respectively. Requests with higher priority will be serviced first.	186	and C<4>, respectively. Requests with higher priority will be serviced
		187	first.
134		188
135	The priority will be reset to C<0> after each call to one of the C<aio_>	189	The priority will be reset to C<0> after each call to one of the C<aio_*>
136	functions.	190	functions.
137		191
138	Example: open a file with low priority, then read something from it with	192	Example: open a file with low priority, then read something from it with
139	higher priority so the read request is serviced before other low priority	193	higher priority so the read request is serviced before other low priority
140	open requests (potentially spamming the cache):	194	open requests (potentially spamming the cache):
…		…
213	print "read $_[0] bytes: <$buffer>\n";	267	print "read $_[0] bytes: <$buffer>\n";
214	};	268	};
215		269
216	=item aio_move $srcpath, $dstpath, $callback->($status)	270	=item aio_move $srcpath, $dstpath, $callback->($status)
217		271
218	[EXPERIMENTAL due to internal aio_group use]
219
220	Try to move the I<file> (directories not supported as either source or	272	Try to move the I<file> (directories not supported as either source or
221	destination) from C<$srcpath> to C<$dstpath> and call the callback with	273	destination) from C<$srcpath> to C<$dstpath> and call the callback with
222	the C<0> (error) or C<-1> ok.	274	the C<0> (error) or C<-1> ok.
223		275
224	This is a composite request that tries to rename(2) the file first. If	276	This is a composite request that tries to rename(2) the file first. If
…		…
234	=cut	286	=cut
235		287
236	sub aio_move($$$) {	288	sub aio_move($$$) {
237	my ($src, $dst, $cb) = @_;	289	my ($src, $dst, $cb) = @_;
238		290
		291	my $pri = aioreq_pri;
239	my $grp = aio_group $cb;	292	my $grp = aio_group $cb;
240		293
		294	aioreq_pri $pri;
241	add $grp aio_rename $src, $dst, sub {	295	add $grp aio_rename $src, $dst, sub {
242	if ($_[0] && $! == EXDEV) {	296	if ($_[0] && $! == EXDEV) {
		297	aioreq_pri $pri;
243	add $grp aio_open $src, O_RDONLY, 0, sub {	298	add $grp aio_open $src, O_RDONLY, 0, sub {
244	if (my $src_fh = $_[0]) {	299	if (my $src_fh = $_[0]) {
245	my @stat = stat $src_fh;	300	my @stat = stat $src_fh;
246		301
		302	aioreq_pri $pri;
247	add $grp aio_open $dst, O_WRONLY, 0200, sub {	303	add $grp aio_open $dst, O_WRONLY, 0200, sub {
248	if (my $dst_fh = $_[0]) {	304	if (my $dst_fh = $_[0]) {
		305	aioreq_pri $pri;
249	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {	306	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
250	close $src_fh;	307	close $src_fh;
251		308
252	if ($_[0] == $stat[7]) {	309	if ($_[0] == $stat[7]) {
253	utime $stat[8], $stat[9], $dst;	310	utime $stat[8], $stat[9], $dst;
254	chmod $stat[2] & 07777, $dst_fh;	311	chmod $stat[2] & 07777, $dst_fh;
255	chown $stat[4], $stat[5], $dst_fh;	312	chown $stat[4], $stat[5], $dst_fh;
256	close $dst_fh;	313	close $dst_fh;
257		314
		315	aioreq_pri $pri;
258	add $grp aio_unlink $src, sub {	316	add $grp aio_unlink $src, sub {
259	$grp->result ($_[0]);	317	$grp->result ($_[0]);
260	};	318	};
261	} else {	319	} else {
262	my $errno = $!;	320	my $errno = $!;
		321	aioreq_pri $pri;
263	add $grp aio_unlink $dst, sub {	322	add $grp aio_unlink $dst, sub {
264	$! = $errno;	323	$! = $errno;
265	$grp->result (-1);	324	$grp->result (-1);
266	};	325	};
267	}	326	}
…		…
376	The callback a single argument which is either C<undef> or an array-ref	435	The callback a single argument which is either C<undef> or an array-ref
377	with the filenames.	436	with the filenames.
378		437
379	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	438	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
380		439
381	[EXPERIMENTAL due to internal aio_group use]
382
383	Scans a directory (similar to C<aio_readdir>) but additionally tries to	440	Scans a directory (similar to C<aio_readdir>) but additionally tries to
384	separate the entries of directory C<$path> into two sets of names, ones	441	efficiently separate the entries of directory C<$path> into two sets of
385	you can recurse into (directories or links to them), and ones you cannot	442	names, directories you can recurse into (directories), and ones you cannot
386	recurse into (everything else).	443	recurse into (everything else, including symlinks to directories).
387		444
388	C<aio_scandir> is a composite request that creates of many sub requests_	445	C<aio_scandir> is a composite request that creates of many sub requests_
389	C<$maxreq> specifies the maximum number of outstanding aio requests that	446	C<$maxreq> specifies the maximum number of outstanding aio requests that
390	this function generates. If it is C<< <= 0 >>, then a suitable default	447	this function generates. If it is C<< <= 0 >>, then a suitable default
391	will be chosen (currently 6).	448	will be chosen (currently 4).
392		449
393	On error, the callback is called without arguments, otherwise it receives	450	On error, the callback is called without arguments, otherwise it receives
394	two array-refs with path-relative entry names.	451	two array-refs with path-relative entry names.
395		452
396	Example:	453	Example:
…		…
433	=cut	490	=cut
434		491
435	sub aio_scandir($$$) {	492	sub aio_scandir($$$) {
436	my ($path, $maxreq, $cb) = @_;	493	my ($path, $maxreq, $cb) = @_;
437		494
		495	my $pri = aioreq_pri;
		496
438	my $grp = aio_group $cb;	497	my $grp = aio_group $cb;
439		498
440	$maxreq = 6 if $maxreq <= 0;	499	$maxreq = 4 if $maxreq <= 0;
441		500
442	# stat once	501	# stat once
		502	aioreq_pri $pri;
443	add $grp aio_stat $path, sub {	503	add $grp aio_stat $path, sub {
444	return $grp->result () if $_[0];	504	return $grp->result () if $_[0];
445	my $now = time;	505	my $now = time;
446	my $hash1 = join ":", (stat _)[0,1,3,7,9];	506	my $hash1 = join ":", (stat _)[0,1,3,7,9];
447		507
448	# read the directory entries	508	# read the directory entries
		509	aioreq_pri $pri;
449	add $grp aio_readdir $path, sub {	510	add $grp aio_readdir $path, sub {
450	my $entries = shift	511	my $entries = shift
451	or return $grp->result ();	512	or return $grp->result ();
452		513
453	# stat the dir another time	514	# stat the dir another time
		515	aioreq_pri $pri;
454	add $grp aio_stat $path, sub {	516	add $grp aio_stat $path, sub {
455	my $hash2 = join ":", (stat _)[0,1,3,7,9];	517	my $hash2 = join ":", (stat _)[0,1,3,7,9];
456		518
457	my $ndirs;	519	my $ndirs;
458		520
…		…
473	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],	535	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
474	@$entries];	536	@$entries];
475		537
476	my (@dirs, @nondirs);	538	my (@dirs, @nondirs);
477		539
478	my ($statcb, $schedcb);
479	my $nreq = 0;
480
481	my $statgrp = add $grp aio_group;	540	my $statgrp = add $grp aio_group sub {
		541	$grp->result (\@dirs, \@nondirs);
		542	};
482		543
483	$schedcb = sub {	544	limit $statgrp $maxreq;
484	if (@$entries) {	545	feed $statgrp sub {
485	if ($nreq < $maxreq) {	546	return unless @$entries;
486	my $ent = pop @$entries;	547	my $entry = pop @$entries;
		548
		549	aioreq_pri $pri;
		550	add $statgrp aio_stat "$path/$entry/.", sub {
		551	if ($_[0] < 0) {
		552	push @nondirs, $entry;
		553	} else {
		554	# need to check for real directory
		555	aioreq_pri $pri;
		556	add $statgrp aio_lstat "$path/$entry", sub {
		557	if (-d _) {
		558	push @dirs, $entry;
		559
		560	unless (--$ndirs) {
		561	push @nondirs, @$entries;
		562	feed $statgrp;
		563	}
		564	} else {
		565	push @nondirs, $entry;
		566	}
487	$nreq++;	567	}
488	add $statgrp aio_stat "$path/$ent/.", sub { $statcb->($_[0], $ent) };
489	}	568	}
490	} elsif (!$nreq) {
491	# finished
492	$statgrp->cancel;
493	undef $statcb;
494	undef $schedcb;
495	$grp->result (\@dirs, \@nondirs);
496	}	569	};
497	};	570	};
498	$statcb = sub {
499	my ($status, $entry) = @_;
500
501	if ($status < 0) {
502	$nreq--;
503	push @nondirs, $entry;
504	&$schedcb;
505	} else {
506	# need to check for real directory
507	add $grp aio_lstat "$path/$entry", sub {
508	$nreq--;
509
510	if (-d _) {
511	push @dirs, $entry;
512
513	if (!--$ndirs) {
514	push @nondirs, @$entries;
515	$entries = [];
516	}
517	} else {
518	push @nondirs, $entry;
519	}
520
521	&$schedcb;
522	}
523	}
524	};
525
526	&$schedcb while @$entries && $nreq < $maxreq;
527	};	571	};
528	};	572	};
529	};	573	};
530		574
531	$grp	575	$grp
…		…
544	If this call isn't available because your OS lacks it or it couldn't be	588	If this call isn't available because your OS lacks it or it couldn't be
545	detected, it will be emulated by calling C<fsync> instead.	589	detected, it will be emulated by calling C<fsync> instead.
546		590
547	=item aio_group $callback->(...)	591	=item aio_group $callback->(...)
548		592
549	[EXPERIMENTAL]
550
551	This is a very special aio request: Instead of doing something, it is a	593	This is a very special aio request: Instead of doing something, it is a
552	container for other aio requests, which is useful if you want to bundle	594	container for other aio requests, which is useful if you want to bundle
553	many requests into a single, composite, request.	595	many requests into a single, composite, request with a definite callback
		596	and the ability to cancel the whole request with its subrequests.
554		597
555	Returns an object of class L<IO::AIO::GRP>. See its documentation below	598	Returns an object of class L<IO::AIO::GRP>. See its documentation below
556	for more info.	599	for more info.
557		600
558	Example:	601	Example:
…		…
577	phase and still requires a worker thread. Thus, the callback will not	620	phase and still requires a worker thread. Thus, the callback will not
578	be executed immediately but only after other requests in the queue have	621	be executed immediately but only after other requests in the queue have
579	entered their execution phase. This can be used to measure request	622	entered their execution phase. This can be used to measure request
580	latency.	623	latency.
581		624
582	=item IO::AIO::aio_sleep $fractional_seconds, $callback->() NOT EXPORTED	625	=item IO::AIO::aio_busy $fractional_seconds, $callback->() NOT EXPORTED
583		626
584	Mainly used for debugging and benchmarking, this aio request puts one of	627	Mainly used for debugging and benchmarking, this aio request puts one of
585	the request workers to sleep for the given time.	628	the request workers to sleep for the given time.
586		629
587	While it is theoretically handy to have simple I/O scheduling requests	630	While it is theoretically handy to have simple I/O scheduling requests
588	like sleep and file handle readable/writable, the overhead this creates	631	like sleep and file handle readable/writable, the overhead this creates is
589	is immense, so do not use this function except to put your application	632	immense (it blocks a thread for a long time) so do not use this function
590	under artificial I/O pressure.	633	except to put your application under artificial I/O pressure.
591		634
592	=back	635	=back
593		636
594	=head2 IO::AIO::REQ CLASS	637	=head2 IO::AIO::REQ CLASS
595		638
596	All non-aggregate C<aio_*> functions return an object of this class when	639	All non-aggregate C<aio_*> functions return an object of this class when
597	called in non-void context.	640	called in non-void context.
598
599	A request always moves through the following five states in its lifetime,
600	in order: B<ready> (request has been created, but has not been executed
601	yet), B<execute> (request is currently being executed), B<pending>
602	(request has been executed but callback has not been called yet),
603	B<result> (results are being processed synchronously, includes calling the
604	callback) and B<done> (request has reached the end of its lifetime and
605	holds no resources anymore).
606		641
607	=over 4	642	=over 4
608		643
609	=item cancel $req	644	=item cancel $req
610		645
…		…
664	=item * They can also can also be added to other IO::AIO::GRP objects.	699	=item * They can also can also be added to other IO::AIO::GRP objects.
665		700
666	=item * You must not add requests to a group from within the group callback (or	701	=item * You must not add requests to a group from within the group callback (or
667	any later time).	702	any later time).
668		703
669	=item * This does not harmonise well with C<max_outstanding>, so best do
670	not combine C<aio_group> with it. Groups and feeders are recommended for
671	this kind of concurrency-limiting.
672
673	=back	704	=back
674		705
675	Their lifetime, simplified, looks like this: when they are empty, they	706	Their lifetime, simplified, looks like this: when they are empty, they
676	will finish very quickly. If they contain only requests that are in the	707	will finish very quickly. If they contain only requests that are in the
677	C<done> state, they will also finish. Otherwise they will continue to	708	C<done> state, they will also finish. Otherwise they will continue to
…		…
692	be added, including other groups, as long as you do not create circular	723	be added, including other groups, as long as you do not create circular
693	dependencies.	724	dependencies.
694		725
695	Returns all its arguments.	726	Returns all its arguments.
696		727
		728	=item $grp->cancel_subs
		729
		730	Cancel all subrequests and clears any feeder, but not the group request
		731	itself. Useful when you queued a lot of events but got a result early.
		732
697	=item $grp->result (...)	733	=item $grp->result (...)
698		734
699	Set the result value(s) that will be passed to the group callback when all	735	Set the result value(s) that will be passed to the group callback when all
700	subrequests have finished. By default, no argument will be passed.	736	subrequests have finished and set thre groups errno to the current value
		737	of errno (just like calling C<errno> without an error number). By default,
		738	no argument will be passed and errno is zero.
		739
		740	=item $grp->errno ([$errno])
		741
		742	Sets the group errno value to C<$errno>, or the current value of errno
		743	when the argument is missing.
		744
		745	Every aio request has an associated errno value that is restored when
		746	the callback is invoked. This method lets you change this value from its
		747	default (0).
		748
		749	Calling C<result> will also set errno, so make sure you either set C<$!>
		750	before the call to C<result>, or call c<errno> after it.
701		751
702	=item feed $grp $callback->($grp)	752	=item feed $grp $callback->($grp)
703
704	[VERY EXPERIMENTAL]
705		753
706	Sets a feeder/generator on this group: every group can have an attached	754	Sets a feeder/generator on this group: every group can have an attached
707	generator that generates requests if idle. The idea behind this is that,	755	generator that generates requests if idle. The idea behind this is that,
708	although you could just queue as many requests as you want in a group,	756	although you could just queue as many requests as you want in a group,
709	this might starve other requests for a potentially long time. For	757	this might starve other requests for a potentially long time. For
…		…
763		811
764	Process all outstanding events on the result pipe. You have to call this	812	Process all outstanding events on the result pipe. You have to call this
765	regularly. Returns the number of events processed. Returns immediately	813	regularly. Returns the number of events processed. Returns immediately
766	when no events are outstanding.	814	when no events are outstanding.
767		815
		816	If not all requests were processed for whatever reason, the filehandle
		817	will still be ready when C<poll_cb> returns.
		818
768	Example: Install an Event watcher that automatically calls	819	Example: Install an Event watcher that automatically calls
769	IO::AIO::poll_cb with high priority:	820	IO::AIO::poll_cb with high priority:
770		821
771	Event->io (fd => IO::AIO::poll_fileno,	822	Event->io (fd => IO::AIO::poll_fileno,
772	poll => 'r', async => 1,	823	poll => 'r', async => 1,
773	cb => \&IO::AIO::poll_cb);	824	cb => \&IO::AIO::poll_cb);
774		825
		826	=item IO::AIO::poll_some $max_requests
		827
		828	Similar to C<poll_cb>, but only processes up to C<$max_requests> requests
		829	at a time.
		830
		831	Useful if you want to ensure some level of interactiveness when perl is
		832	not fast enough to process all requests in time.
		833
		834	Example: Install an Event watcher that automatically calls
		835	IO::AIO::poll_some with low priority, to ensure that other parts of the
		836	program get the CPU sometimes even under high AIO load.
		837
		838	Event->io (fd => IO::AIO::poll_fileno,
		839	poll => 'r', nice => 1,
		840	cb => sub { IO::AIO::poll_some 256 });
		841
775	=item IO::AIO::poll_wait	842	=item IO::AIO::poll_wait
776		843
777	Wait till the result filehandle becomes ready for reading (simply does a	844	Wait till the result filehandle becomes ready for reading (simply does a
778	C<select> on the filehandle. This is useful if you want to synchronously wait	845	C<select> on the filehandle. This is useful if you want to synchronously wait
779	for some requests to finish).	846	for some requests to finish).
780		847
781	See C<nreqs> for an example.	848	See C<nreqs> for an example.
782		849
783	=item IO::AIO::nreqs	850	=item IO::AIO::nreqs
784		851
785	Returns the number of requests currently outstanding (i.e. for which their	852	Returns the number of requests currently in the ready, execute or pending
786	callback has not been invoked yet).	853	states (i.e. for which their callback has not been invoked yet).
787		854
788	Example: wait till there are no outstanding requests anymore:	855	Example: wait till there are no outstanding requests anymore:
789		856
790	IO::AIO::poll_wait, IO::AIO::poll_cb	857	IO::AIO::poll_wait, IO::AIO::poll_cb
791	while IO::AIO::nreqs;	858	while IO::AIO::nreqs;
		859
		860	=item IO::AIO::nready
		861
		862	Returns the number of requests currently in the ready state (not yet
		863	executed).
		864
		865	=item IO::AIO::npending
		866
		867	Returns the number of requests currently in the pending state (executed,
		868	but not yet processed by poll_cb).
792		869
793	=item IO::AIO::flush	870	=item IO::AIO::flush
794		871
795	Wait till all outstanding AIO requests have been handled.	872	Wait till all outstanding AIO requests have been handled.
796		873
…		…
838	This module automatically runs C<max_parallel 0> at program end, to ensure	915	This module automatically runs C<max_parallel 0> at program end, to ensure
839	that all threads are killed and that there are no outstanding requests.	916	that all threads are killed and that there are no outstanding requests.
840		917
841	Under normal circumstances you don't need to call this function.	918	Under normal circumstances you don't need to call this function.
842		919
843	=item $oldnreqs = IO::AIO::max_outstanding $nreqs	920	=item $oldmaxreqs = IO::AIO::max_outstanding $maxreqs
844		921
845	[DEPRECATED]	922	This is a very bad function to use in interactive programs because it
		923	blocks, and a bad way to reduce concurrency because it is inexact: Better
		924	use an C<aio_group> together with a feed callback.
846		925
847	Sets the maximum number of outstanding requests to C<$nreqs>. If you	926	Sets the maximum number of outstanding requests to C<$nreqs>. If you
848	try to queue up more than this number of requests, the caller will block until	927	to queue up more than this number of requests, the next call to the
849	some requests have been handled.	928	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
		929	function will block until the limit is no longer exceeded.
850		930
851	The default is very large, so normally there is no practical limit. If you	931	The default value is very large, so there is no practical limit on the
852	queue up many requests in a loop it often improves speed if you set	932	number of outstanding requests.
853	this to a relatively low number, such as C<100>.
854		933
855	This function does not work well together with C<aio_group>'s, and their	934	You can still queue as many requests as you want. Therefore,
856	feeder interface is better suited to limiting concurrency, so do not use	935	C<max_oustsanding> is mainly useful in simple scripts (with low values) or
857	this function.	936	as a stop gap to shield against fatal memory overflow (with large values).
858
859	Under normal circumstances you don't need to call this function.
860		937
861	=back	938	=back
862		939
863	=cut	940	=cut
864		941
…		…
878	*$sym	955	*$sym
879	}	956	}
880		957
881	min_parallel 8;	958	min_parallel 8;
882		959
883	END {
884	max_parallel 0;
885	}
886
887	1;	960	1;
888		961
889	=head2 FORK BEHAVIOUR	962	=head2 FORK BEHAVIOUR
890		963
891	This module should do "the right thing" when the process using it forks:	964	This module should do "the right thing" when the process using it forks:
892		965
893	Before the fork, IO::AIO enters a quiescent state where no requests	966	Before the fork, IO::AIO enters a quiescent state where no requests
894	can be added in other threads and no results will be processed. After	967	can be added in other threads and no results will be processed. After
895	the fork the parent simply leaves the quiescent state and continues	968	the fork the parent simply leaves the quiescent state and continues
896	request/result processing, while the child clears the request/result	969	request/result processing, while the child frees the request/result queue
897	queue (so the requests started before the fork will only be handled in	970	(so that the requests started before the fork will only be handled in the
898	the parent). Threads will be started on demand until the limit ste in the	971	parent). Threads will be started on demand until the limit set in the
899	parent process has been reached again.	972	parent process has been reached again.
900		973
901	In short: the parent will, after a short pause, continue as if fork had	974	In short: the parent will, after a short pause, continue as if fork had
902	not been called, while the child will act as if IO::AIO has not been used	975	not been called, while the child will act as if IO::AIO has not been used
903	yet.	976	yet.
904		977
905	=head2 MEMORY USAGE	978	=head2 MEMORY USAGE
906		979
		980	Per-request usage:
		981
907	Each aio request uses - depending on your architecture - around 128 bytes	982	Each aio request uses - depending on your architecture - around 100-200
908	of memory. In addition, stat requests need a stat buffer (possibly a few	983	bytes of memory. In addition, stat requests need a stat buffer (possibly
909	hundred bytes). Perl scalars and other data passed into aio requests will	984	a few hundred bytes), readdir requires a result buffer and so on. Perl
910	also be locked.	985	scalars and other data passed into aio requests will also be locked and
		986	will consume memory till the request has entered the done state.
911		987
912	This is now awfully much, so queuing lots of requests is not usually a	988	This is now awfully much, so queuing lots of requests is not usually a
913	problem.	989	problem.
914		990
915	Each thread needs a stack area which is usually around 16k, sometimes much	991	Per-thread usage:
916	larger, depending on the OS.	992
		993	In the execution phase, some aio requests require more memory for
		994	temporary buffers, and each thread requires a stack and other data
		995	structures (usually around 16k-128k, depending on the OS).
		996
		997	=head1 KNOWN BUGS
		998
		999	Known bugs will be fixed in the next release.
917		1000
918	=head1 SEE ALSO	1001	=head1 SEE ALSO
919		1002
920	L<Coro::AIO>.	1003	L<Coro::AIO>.
921		1004

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Comparing IO-AIO/AIO.pm (file contents): Revision 1.70 by root, Tue Oct 24 03:40:38 2006 UTC vs. Revision 1.81 by root, Fri Oct 27 19:17:23 2006 UTC

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Comparing IO-AIO/AIO.pm (file contents):
Revision 1.70 by root, Tue Oct 24 03:40:38 2006 UTC vs.
Revision 1.81 by root, Fri Oct 27 19:17:23 2006 UTC