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

Comparing IO-AIO/AIO.pm (file contents):
Revision 1.67 by root, Tue Oct 24 02:25:16 2006 UTC vs.
Revision 1.81 by root, Fri Oct 27 19:17:23 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 perl, and	57	requests and signal their completion. You don't need thread support
57	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
58	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
59	on many operating systems. However, they are often not well-supported	60	functions available on many operating systems. However, they are often
60	(Linux doesn't allow them on normal files currently, for example),	61	not well-supported or restricted (Linux doesn't allow them on normal
61	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
62	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
…		…
80		132
81	our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close aio_stat	133	our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close aio_stat
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 = (@AIO_REQ, qw(aioreq_pri));	137	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
86	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush	138	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
87	min_parallel max_parallel max_outstanding nreqs);	139	min_parallel max_parallel nreqs nready npending);
88		140
89	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';	141	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';
90		142
91	require XSLoader;	143	require XSLoader;
92	XSLoader::load ("IO::AIO", $VERSION);	144	XSLoader::load ("IO::AIO", $VERSION);
…		…
122	your pathnames to the locale (or other) encoding in effect in the user	174	your pathnames to the locale (or other) encoding in effect in the user
123	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)
124	use something else.	176	use something else.
125		177
126	=over 4	178	=over 4
		179
		180	=item $prev_pri = aioreq_pri [$pri]
		181
		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
		185	The default priority is C<0>, the minimum and maximum priorities are C<-4>
		186	and C<4>, respectively. Requests with higher priority will be serviced
		187	first.
		188
		189	The priority will be reset to C<0> after each call to one of the C<aio_*>
		190	functions.
		191
		192	Example: open a file with low priority, then read something from it with
		193	higher priority so the read request is serviced before other low priority
		194	open requests (potentially spamming the cache):
		195
		196	aioreq_pri -3;
		197	aio_open ..., sub {
		198	return unless $_[0];
		199
		200	aioreq_pri -2;
		201	aio_read $_[0], ..., sub {
		202	...
		203	};
		204	};
		205
		206	=item aioreq_nice $pri_adjust
		207
		208	Similar to C<aioreq_pri>, but subtracts the given value from the current
		209	priority, so effects are cumulative.
127		210
128	=item aio_open $pathname, $flags, $mode, $callback->($fh)	211	=item aio_open $pathname, $flags, $mode, $callback->($fh)
129		212
130	Asynchronously open or create a file and call the callback with a newly	213	Asynchronously open or create a file and call the callback with a newly
131	created filehandle for the file.	214	created filehandle for the file.
…		…
184	print "read $_[0] bytes: <$buffer>\n";	267	print "read $_[0] bytes: <$buffer>\n";
185	};	268	};
186		269
187	=item aio_move $srcpath, $dstpath, $callback->($status)	270	=item aio_move $srcpath, $dstpath, $callback->($status)
188		271
189	[EXPERIMENTAL due to internal aio_group use]
190
191	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
192	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
193	the C<0> (error) or C<-1> ok.	274	the C<0> (error) or C<-1> ok.
194		275
195	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
…		…
205	=cut	286	=cut
206		287
207	sub aio_move($$$) {	288	sub aio_move($$$) {
208	my ($src, $dst, $cb) = @_;	289	my ($src, $dst, $cb) = @_;
209		290
		291	my $pri = aioreq_pri;
210	my $grp = aio_group $cb;	292	my $grp = aio_group $cb;
211		293
		294	aioreq_pri $pri;
212	add $grp aio_rename $src, $dst, sub {	295	add $grp aio_rename $src, $dst, sub {
213	if ($_[0] && $! == EXDEV) {	296	if ($_[0] && $! == EXDEV) {
		297	aioreq_pri $pri;
214	add $grp aio_open $src, O_RDONLY, 0, sub {	298	add $grp aio_open $src, O_RDONLY, 0, sub {
215	if (my $src_fh = $_[0]) {	299	if (my $src_fh = $_[0]) {
216	my @stat = stat $src_fh;	300	my @stat = stat $src_fh;
217		301
		302	aioreq_pri $pri;
218	add $grp aio_open $dst, O_WRONLY, 0200, sub {	303	add $grp aio_open $dst, O_WRONLY, 0200, sub {
219	if (my $dst_fh = $_[0]) {	304	if (my $dst_fh = $_[0]) {
		305	aioreq_pri $pri;
220	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 {
221	close $src_fh;	307	close $src_fh;
222		308
223	if ($_[0] == $stat[7]) {	309	if ($_[0] == $stat[7]) {
224	utime $stat[8], $stat[9], $dst;	310	utime $stat[8], $stat[9], $dst;
225	chmod $stat[2] & 07777, $dst_fh;	311	chmod $stat[2] & 07777, $dst_fh;
226	chown $stat[4], $stat[5], $dst_fh;	312	chown $stat[4], $stat[5], $dst_fh;
227	close $dst_fh;	313	close $dst_fh;
228		314
		315	aioreq_pri $pri;
229	add $grp aio_unlink $src, sub {	316	add $grp aio_unlink $src, sub {
230	$grp->result ($_[0]);	317	$grp->result ($_[0]);
231	};	318	};
232	} else {	319	} else {
233	my $errno = $!;	320	my $errno = $!;
		321	aioreq_pri $pri;
234	add $grp aio_unlink $dst, sub {	322	add $grp aio_unlink $dst, sub {
235	$! = $errno;	323	$! = $errno;
236	$grp->result (-1);	324	$grp->result (-1);
237	};	325	};
238	}	326	}
…		…
347	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
348	with the filenames.	436	with the filenames.
349		437
350	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	438	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
351		439
352	[EXPERIMENTAL due to internal aio_group use]
353
354	Scans a directory (similar to C<aio_readdir>) but additionally tries to	440	Scans a directory (similar to C<aio_readdir>) but additionally tries to
355	separate the entries of directory C<$path> into two sets of names, ones	441	efficiently separate the entries of directory C<$path> into two sets of
356	you can recurse into (directories or links to them), and ones you cannot	442	names, directories you can recurse into (directories), and ones you cannot
357	recurse into (everything else).	443	recurse into (everything else, including symlinks to directories).
358		444
359	C<aio_scandir> is a composite request that creates of many sub requests_	445	C<aio_scandir> is a composite request that creates of many sub requests_
360	C<$maxreq> specifies the maximum number of outstanding aio requests that	446	C<$maxreq> specifies the maximum number of outstanding aio requests that
361	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
362	will be chosen (currently 6).	448	will be chosen (currently 4).
363		449
364	On error, the callback is called without arguments, otherwise it receives	450	On error, the callback is called without arguments, otherwise it receives
365	two array-refs with path-relative entry names.	451	two array-refs with path-relative entry names.
366		452
367	Example:	453	Example:
…		…
404	=cut	490	=cut
405		491
406	sub aio_scandir($$$) {	492	sub aio_scandir($$$) {
407	my ($path, $maxreq, $cb) = @_;	493	my ($path, $maxreq, $cb) = @_;
408		494
		495	my $pri = aioreq_pri;
		496
409	my $grp = aio_group $cb;	497	my $grp = aio_group $cb;
410		498
411	$maxreq = 6 if $maxreq <= 0;	499	$maxreq = 4 if $maxreq <= 0;
412		500
413	# stat once	501	# stat once
		502	aioreq_pri $pri;
414	add $grp aio_stat $path, sub {	503	add $grp aio_stat $path, sub {
415	return $grp->result () if $_[0];	504	return $grp->result () if $_[0];
416	my $now = time;	505	my $now = time;
417	my $hash1 = join ":", (stat _)[0,1,3,7,9];	506	my $hash1 = join ":", (stat _)[0,1,3,7,9];
418		507
419	# read the directory entries	508	# read the directory entries
		509	aioreq_pri $pri;
420	add $grp aio_readdir $path, sub {	510	add $grp aio_readdir $path, sub {
421	my $entries = shift	511	my $entries = shift
422	or return $grp->result ();	512	or return $grp->result ();
423		513
424	# stat the dir another time	514	# stat the dir another time
		515	aioreq_pri $pri;
425	add $grp aio_stat $path, sub {	516	add $grp aio_stat $path, sub {
426	my $hash2 = join ":", (stat _)[0,1,3,7,9];	517	my $hash2 = join ":", (stat _)[0,1,3,7,9];
427		518
428	my $ndirs;	519	my $ndirs;
429		520
…		…
444	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],	535	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
445	@$entries];	536	@$entries];
446		537
447	my (@dirs, @nondirs);	538	my (@dirs, @nondirs);
448		539
449	my ($statcb, $schedcb);
450	my $nreq = 0;
451
452	my $statgrp = add $grp aio_group;	540	my $statgrp = add $grp aio_group sub {
		541	$grp->result (\@dirs, \@nondirs);
		542	};
453		543
454	$schedcb = sub {	544	limit $statgrp $maxreq;
455	if (@$entries) {	545	feed $statgrp sub {
456	if ($nreq < $maxreq) {	546	return unless @$entries;
457	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	}
458	$nreq++;	567	}
459	add $statgrp aio_stat "$path/$ent/.", sub { $statcb->($_[0], $ent) };
460	}	568	}
461	} elsif (!$nreq) {
462	# finished
463	$statgrp->cancel;
464	undef $statcb;
465	undef $schedcb;
466	$grp->result (\@dirs, \@nondirs);
467	}	569	};
468	};	570	};
469	$statcb = sub {
470	my ($status, $entry) = @_;
471
472	if ($status < 0) {
473	$nreq--;
474	push @nondirs, $entry;
475	&$schedcb;
476	} else {
477	# need to check for real directory
478	add $grp aio_lstat "$path/$entry", sub {
479	$nreq--;
480
481	if (-d _) {
482	push @dirs, $entry;
483
484	if (!--$ndirs) {
485	push @nondirs, @$entries;
486	$entries = [];
487	}
488	} else {
489	push @nondirs, $entry;
490	}
491
492	&$schedcb;
493	}
494	}
495	};
496
497	&$schedcb while @$entries && $nreq < $maxreq;
498	};	571	};
499	};	572	};
500	};	573	};
501		574
502	$grp	575	$grp
…		…
515	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
516	detected, it will be emulated by calling C<fsync> instead.	589	detected, it will be emulated by calling C<fsync> instead.
517		590
518	=item aio_group $callback->(...)	591	=item aio_group $callback->(...)
519		592
520	[EXPERIMENTAL]
521
522	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
523	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
524	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.
525		597
526	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
527	for more info.	599	for more info.
528		600
529	Example:	601	Example:
…		…
548	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
549	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
550	entered their execution phase. This can be used to measure request	622	entered their execution phase. This can be used to measure request
551	latency.	623	latency.
552		624
553	=item IO::AIO::aio_sleep $fractional_seconds, $callback->() NOT EXPORTED	625	=item IO::AIO::aio_busy $fractional_seconds, $callback->() NOT EXPORTED
554		626
555	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
556	the request workers to sleep for the given time.	628	the request workers to sleep for the given time.
557		629
558	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
559	like sleep and file handle readable/writable, the overhead this creates	631	like sleep and file handle readable/writable, the overhead this creates is
560	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
561	under artificial I/O pressure.	633	except to put your application under artificial I/O pressure.
562		634
563	=back	635	=back
564		636
565	=head2 IO::AIO::REQ CLASS	637	=head2 IO::AIO::REQ CLASS
566		638
567	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
568	called in non-void context.	640	called in non-void context.
569
570	A request always moves through the following five states in its lifetime,
571	in order: B<ready> (request has been created, but has not been executed
572	yet), B<execute> (request is currently being executed), B<pending>
573	(request has been executed but callback has not been called yet),
574	B<result> (results are being processed synchronously, includes calling the
575	callback) and B<done> (request has reached the end of its lifetime and
576	holds no resources anymore).
577		641
578	=over 4	642	=over 4
579		643
580	=item cancel $req	644	=item cancel $req
581		645
…		…
635	=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.
636		700
637	=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
638	any later time).	702	any later time).
639		703
640	=item * This does not harmonise well with C<max_outstanding>, so best do
641	not combine C<aio_group> with it. Groups and feeders are recommended for
642	this kind of concurrency-limiting.
643
644	=back	704	=back
645		705
646	Their lifetime, simplified, looks like this: when they are empty, they	706	Their lifetime, simplified, looks like this: when they are empty, they
647	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
648	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
…		…
663	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
664	dependencies.	724	dependencies.
665		725
666	Returns all its arguments.	726	Returns all its arguments.
667		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
668	=item $grp->result (...)	733	=item $grp->result (...)
669		734
670	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
671	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.
672		751
673	=item feed $grp $callback->($grp)	752	=item feed $grp $callback->($grp)
674
675	[VERY EXPERIMENTAL]
676		753
677	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
678	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,
679	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,
680	this might starve other requests for a potentially long time. For	757	this might starve other requests for a potentially long time. For
681	example, C<aio_scandir> might generate hundreds of thousands C<aio_stat>	758	example, C<aio_scandir> might generate hundreds of thousands C<aio_stat>
682	requests, delaying any later requests for a long time.	759	requests, delaying any later requests for a long time.
683		760
684	To avoid this, and allow incremental generation of requests, you can	761	To avoid this, and allow incremental generation of requests, you can
685	instead a group and set a feeder on it that generates those requests. The	762	instead a group and set a feeder on it that generates those requests. The
686	feed callback will be called whenever there are few enough (see C<feed_limit>,	763	feed callback will be called whenever there are few enough (see C<limit>,
687	below) requests active in the group itself and is expected to queue more	764	below) requests active in the group itself and is expected to queue more
688	requests.	765	requests.
689		766
690	The feed can queue as many requests as it likes (i.e. C<add> does not	767	The feed callback can queue as many requests as it likes (i.e. C<add> does
691	impose any limits).	768	not impose any limits).
692		769
693	If the feed does not queue more requests when called, it will be	770	If the feed does not queue more requests when called, it will be
694	automatically removed from the group.	771	automatically removed from the group.
695		772
696	If the feed limit is C<0>, it will be set to C<2> automatically.	773	If the feed limit is C<0>, it will be set to C<2> automatically.
…		…
698	Example:	775	Example:
699		776
700	# stat all files in @files, but only ever use four aio requests concurrently:	777	# stat all files in @files, but only ever use four aio requests concurrently:
701		778
702	my $grp = aio_group sub { print "finished\n" };	779	my $grp = aio_group sub { print "finished\n" };
703	feed_limit $grp 4;	780	limit $grp 4;
704	feed $grp sub {	781	feed $grp sub {
705	my $file = pop @files	782	my $file = pop @files
706	or return;	783	or return;
707		784
708	add $grp aio_stat $file, sub { ... };	785	add $grp aio_stat $file, sub { ... };
709	};	786	};
710		787
711	=item feed_limit $grp $num	788	=item limit $grp $num
712		789
713	Sets the feeder limit for the group: The feeder will be called whenever	790	Sets the feeder limit for the group: The feeder will be called whenever
714	the group contains less than this many requests.	791	the group contains less than this many requests.
715		792
716	Setting the limit to C<0> will pause the feeding process.	793	Setting the limit to C<0> will pause the feeding process.
…		…
734		811
735	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
736	regularly. Returns the number of events processed. Returns immediately	813	regularly. Returns the number of events processed. Returns immediately
737	when no events are outstanding.	814	when no events are outstanding.
738		815
		816	If not all requests were processed for whatever reason, the filehandle
		817	will still be ready when C<poll_cb> returns.
		818
739	Example: Install an Event watcher that automatically calls	819	Example: Install an Event watcher that automatically calls
740	IO::AIO::poll_cb with high priority:	820	IO::AIO::poll_cb with high priority:
741		821
742	Event->io (fd => IO::AIO::poll_fileno,	822	Event->io (fd => IO::AIO::poll_fileno,
743	poll => 'r', async => 1,	823	poll => 'r', async => 1,
744	cb => \&IO::AIO::poll_cb);	824	cb => \&IO::AIO::poll_cb);
745		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
746	=item IO::AIO::poll_wait	842	=item IO::AIO::poll_wait
747		843
748	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
749	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
750	for some requests to finish).	846	for some requests to finish).
751		847
752	See C<nreqs> for an example.	848	See C<nreqs> for an example.
753		849
754	=item IO::AIO::nreqs	850	=item IO::AIO::nreqs
755		851
756	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
757	callback has not been invoked yet).	853	states (i.e. for which their callback has not been invoked yet).
758		854
759	Example: wait till there are no outstanding requests anymore:	855	Example: wait till there are no outstanding requests anymore:
760		856
761	IO::AIO::poll_wait, IO::AIO::poll_cb	857	IO::AIO::poll_wait, IO::AIO::poll_cb
762	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).
763		869
764	=item IO::AIO::flush	870	=item IO::AIO::flush
765		871
766	Wait till all outstanding AIO requests have been handled.	872	Wait till all outstanding AIO requests have been handled.
767		873
…		…
809	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
810	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.
811		917
812	Under normal circumstances you don't need to call this function.	918	Under normal circumstances you don't need to call this function.
813		919
814	=item $oldnreqs = IO::AIO::max_outstanding $nreqs	920	=item $oldmaxreqs = IO::AIO::max_outstanding $maxreqs
815		921
816	[DEPRECATED]	922	This is a very bad function to use in interactive programs because it
		923	blocks, and a bad way to reduce concurrency because it is inexact: Better
		924	use an C<aio_group> together with a feed callback.
817		925
818	Sets the maximum number of outstanding requests to C<$nreqs>. If you	926	Sets the maximum number of outstanding requests to C<$nreqs>. If you
819	try to queue up more than this number of requests, the caller will block until	927	to queue up more than this number of requests, the next call to the
820	some requests have been handled.	928	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
		929	function will block until the limit is no longer exceeded.
821		930
822	The default is very large, so normally there is no practical limit. If you	931	The default value is very large, so there is no practical limit on the
823	queue up many requests in a loop it often improves speed if you set	932	number of outstanding requests.
824	this to a relatively low number, such as C<100>.
825		933
826	This function does not work well together with C<aio_group>'s, and their	934	You can still queue as many requests as you want. Therefore,
827	feeder interface is better suited to limiting concurrency, so do not use	935	C<max_oustsanding> is mainly useful in simple scripts (with low values) or
828	this function.	936	as a stop gap to shield against fatal memory overflow (with large values).
829
830	Under normal circumstances you don't need to call this function.
831		937
832	=back	938	=back
833		939
834	=cut	940	=cut
835		941
…		…
849	*$sym	955	*$sym
850	}	956	}
851		957
852	min_parallel 8;	958	min_parallel 8;
853		959
854	END {
855	max_parallel 0;
856	}
857
858	1;	960	1;
859		961
860	=head2 FORK BEHAVIOUR	962	=head2 FORK BEHAVIOUR
861		963
862	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:
863		965
864	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
865	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
866	the fork the parent simply leaves the quiescent state and continues	968	the fork the parent simply leaves the quiescent state and continues
867	request/result processing, while the child clears the request/result	969	request/result processing, while the child frees the request/result queue
868	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
869	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
870	parent process has been reached again.	972	parent process has been reached again.
871		973
872	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
873	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
874	yet.	976	yet.
875		977
876	=head2 MEMORY USAGE	978	=head2 MEMORY USAGE
877		979
		980	Per-request usage:
		981
878	Each aio request uses - depending on your architecture - around 128 bytes	982	Each aio request uses - depending on your architecture - around 100-200
879	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
880	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
881	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.
882		987
883	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
884	problem.	989	problem.
885		990
886	Each thread needs a stack area which is usually around 16k, sometimes much	991	Per-thread usage:
887	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.
888		1000
889	=head1 SEE ALSO	1001	=head1 SEE ALSO
890		1002
891	L<Coro>, L<Linux::AIO> (obsolete).	1003	L<Coro::AIO>.
892		1004
893	=head1 AUTHOR	1005	=head1 AUTHOR
894		1006
895	Marc Lehmann <schmorp@schmorp.de>	1007	Marc Lehmann <schmorp@schmorp.de>
896	http://home.schmorp.de/	1008	http://home.schmorp.de/

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Comparing IO-AIO/AIO.pm (file contents): Revision 1.67 by root, Tue Oct 24 02:25:16 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 1.67 by root, Tue Oct 24 02:25:16 2006 UTC vs.
Revision 1.81 by root, Fri Oct 27 19:17:23 2006 UTC