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

Comparing IO-AIO/AIO.pm (file contents):
Revision 1.68 by root, Tue Oct 24 03:17:39 2006 UTC vs.
Revision 1.84 by root, Sat Oct 28 00:17:30 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
…		…
80	our $VERSION = '2.0';	131	our $VERSION = '2.0';
81		132
82	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
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_copy aio_group aio_nop aio_mknod);
86	our @EXPORT = (@AIO_REQ, qw(aioreq_pri));	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.
		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.
137		210
138	=item aio_open $pathname, $flags, $mode, $callback->($fh)	211	=item aio_open $pathname, $flags, $mode, $callback->($fh)
139		212
140	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
141	created filehandle for the file.	214	created filehandle for the file.
…		…
191		264
192	aio_read $fh, 7, 15, $buffer, 0, sub {	265	aio_read $fh, 7, 15, $buffer, 0, sub {
193	$_[0] > 0 or die "read error: $!";	266	$_[0] > 0 or die "read error: $!";
194	print "read $_[0] bytes: <$buffer>\n";	267	print "read $_[0] bytes: <$buffer>\n";
195	};	268	};
196
197	=item aio_move $srcpath, $dstpath, $callback->($status)
198
199	[EXPERIMENTAL due to internal aio_group use]
200
201	Try to move the I<file> (directories not supported as either source or
202	destination) from C<$srcpath> to C<$dstpath> and call the callback with
203	the C<0> (error) or C<-1> ok.
204
205	This is a composite request that tries to rename(2) the file first. If
206	rename files with C<EXDEV>, it creates the destination file with mode 0200
207	and copies the contents of the source file into it using C<aio_sendfile>,
208	followed by restoring atime, mtime, access mode and uid/gid, in that
209	order, and unlinking the C<$srcpath>.
210
211	If an error occurs, the partial destination file will be unlinked, if
212	possible, except when setting atime, mtime, access mode and uid/gid, where
213	errors are being ignored.
214
215	=cut
216
217	sub aio_move($$$) {
218	my ($src, $dst, $cb) = @_;
219
220	my $grp = aio_group $cb;
221
222	add $grp aio_rename $src, $dst, sub {
223	if ($_[0] && $! == EXDEV) {
224	add $grp aio_open $src, O_RDONLY, 0, sub {
225	if (my $src_fh = $_[0]) {
226	my @stat = stat $src_fh;
227
228	add $grp aio_open $dst, O_WRONLY, 0200, sub {
229	if (my $dst_fh = $_[0]) {
230	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
231	close $src_fh;
232
233	if ($_[0] == $stat[7]) {
234	utime $stat[8], $stat[9], $dst;
235	chmod $stat[2] & 07777, $dst_fh;
236	chown $stat[4], $stat[5], $dst_fh;
237	close $dst_fh;
238
239	add $grp aio_unlink $src, sub {
240	$grp->result ($_[0]);
241	};
242	} else {
243	my $errno = $!;
244	add $grp aio_unlink $dst, sub {
245	$! = $errno;
246	$grp->result (-1);
247	};
248	}
249	};
250	} else {
251	$grp->result (-1);
252	}
253	},
254
255	} else {
256	$grp->result (-1);
257	}
258	};
259	} else {
260	$grp->result ($_[0]);
261	}
262	};
263
264	$grp
265	}
266		269
267	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)	270	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
268		271
269	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts	272	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
270	reading at byte offset C<$in_offset>, and starts writing at the current	273	reading at byte offset C<$in_offset>, and starts writing at the current
…		…
326	=item aio_unlink $pathname, $callback->($status)	329	=item aio_unlink $pathname, $callback->($status)
327		330
328	Asynchronously unlink (delete) a file and call the callback with the	331	Asynchronously unlink (delete) a file and call the callback with the
329	result code.	332	result code.
330		333
		334	=item aio_mknod $path, $mode, $dev, $callback->($status)
		335
		336	Asynchronously create a device node (or fifo). See mknod(2).
		337
		338	The only portable (POSIX) way of calling this function is:
		339
		340	aio_mknod $path, IO::AIO::S_IFIFO \| $mode, 0, sub { ...
		341
331	=item aio_link $srcpath, $dstpath, $callback->($status)	342	=item aio_link $srcpath, $dstpath, $callback->($status)
332		343
333	Asynchronously create a new link to the existing object at C<$srcpath> at	344	Asynchronously create a new link to the existing object at C<$srcpath> at
334	the path C<$dstpath> and call the callback with the result code.	345	the path C<$dstpath> and call the callback with the result code.
335		346
…		…
355	sorted, and will B<NOT> include the C<.> and C<..> entries.	366	sorted, and will B<NOT> include the C<.> and C<..> entries.
356		367
357	The callback a single argument which is either C<undef> or an array-ref	368	The callback a single argument which is either C<undef> or an array-ref
358	with the filenames.	369	with the filenames.
359		370
		371	=item aio_copy $srcpath, $dstpath, $callback->($status)
		372
		373	Try to copy the I<file> (directories not supported as either source or
		374	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		375	the C<0> (error) or C<-1> ok.
		376
		377	This is a composite request that it creates the destination file with
		378	mode 0200 and copies the contents of the source file into it using
		379	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
		380	uid/gid, in that order.
		381
		382	If an error occurs, the partial destination file will be unlinked, if
		383	possible, except when setting atime, mtime, access mode and uid/gid, where
		384	errors are being ignored.
		385
		386	=cut
		387
		388	sub aio_copy($$;$) {
		389	my ($src, $dst, $cb) = @_;
		390
		391	my $pri = aioreq_pri;
		392	my $grp = aio_group $cb;
		393
		394	aioreq_pri $pri;
		395	add $grp aio_open $src, O_RDONLY, 0, sub {
		396	if (my $src_fh = $_[0]) {
		397	my @stat = stat $src_fh;
		398
		399	aioreq_pri $pri;
		400	add $grp aio_open $dst, O_CREAT \| O_WRONLY \| O_TRUNC, 0200, sub {
		401	if (my $dst_fh = $_[0]) {
		402	aioreq_pri $pri;
		403	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
		404	if ($_[0] == $stat[7]) {
		405	$grp->result (0);
		406	close $src_fh;
		407
		408	# those should not normally block. should. should.
		409	utime $stat[8], $stat[9], $dst;
		410	chmod $stat[2] & 07777, $dst_fh;
		411	chown $stat[4], $stat[5], $dst_fh;
		412	close $dst_fh;
		413	} else {
		414	$grp->result (-1);
		415	close $src_fh;
		416	close $dst_fh;
		417
		418	aioreq $pri;
		419	add $grp aio_unlink $dst;
		420	}
		421	};
		422	} else {
		423	$grp->result (-1);
		424	}
		425	},
		426
		427	} else {
		428	$grp->result (-1);
		429	}
		430	};
		431
		432	$grp
		433	}
		434
		435	=item aio_move $srcpath, $dstpath, $callback->($status)
		436
		437	Try to move the I<file> (directories not supported as either source or
		438	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		439	the C<0> (error) or C<-1> ok.
		440
		441	This is a composite request that tries to rename(2) the file first. If
		442	rename files with C<EXDEV>, it copies the file with C<aio_copy> and, if
		443	that is successful, unlinking the C<$srcpath>.
		444
		445	=cut
		446
		447	sub aio_move($$;$) {
		448	my ($src, $dst, $cb) = @_;
		449
		450	my $pri = aioreq_pri;
		451	my $grp = aio_group $cb;
		452
		453	aioreq_pri $pri;
		454	add $grp aio_rename $src, $dst, sub {
		455	if ($_[0] && $! == EXDEV) {
		456	aioreq_pri $pri;
		457	add $grp aio_copy $src, $dst, sub {
		458	$grp->result ($_[0]);
		459
		460	if (!$_[0]) {
		461	aioreq_pri $pri;
		462	add $grp aio_unlink $src;
		463	}
		464	};
		465	} else {
		466	$grp->result ($_[0]);
		467	}
		468	};
		469
		470	$grp
		471	}
		472
360	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	473	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
361		474
362	[EXPERIMENTAL due to internal aio_group use]
363
364	Scans a directory (similar to C<aio_readdir>) but additionally tries to	475	Scans a directory (similar to C<aio_readdir>) but additionally tries to
365	separate the entries of directory C<$path> into two sets of names, ones	476	efficiently separate the entries of directory C<$path> into two sets of
366	you can recurse into (directories or links to them), and ones you cannot	477	names, directories you can recurse into (directories), and ones you cannot
367	recurse into (everything else).	478	recurse into (everything else, including symlinks to directories).
368		479
369	C<aio_scandir> is a composite request that creates of many sub requests_	480	C<aio_scandir> is a composite request that creates of many sub requests_
370	C<$maxreq> specifies the maximum number of outstanding aio requests that	481	C<$maxreq> specifies the maximum number of outstanding aio requests that
371	this function generates. If it is C<< <= 0 >>, then a suitable default	482	this function generates. If it is C<< <= 0 >>, then a suitable default
372	will be chosen (currently 6).	483	will be chosen (currently 4).
373		484
374	On error, the callback is called without arguments, otherwise it receives	485	On error, the callback is called without arguments, otherwise it receives
375	two array-refs with path-relative entry names.	486	two array-refs with path-relative entry names.
376		487
377	Example:	488	Example:
…		…
414	=cut	525	=cut
415		526
416	sub aio_scandir($$$) {	527	sub aio_scandir($$$) {
417	my ($path, $maxreq, $cb) = @_;	528	my ($path, $maxreq, $cb) = @_;
418		529
		530	my $pri = aioreq_pri;
		531
419	my $grp = aio_group $cb;	532	my $grp = aio_group $cb;
420		533
421	$maxreq = 6 if $maxreq <= 0;	534	$maxreq = 4 if $maxreq <= 0;
422		535
423	# stat once	536	# stat once
		537	aioreq_pri $pri;
424	add $grp aio_stat $path, sub {	538	add $grp aio_stat $path, sub {
425	return $grp->result () if $_[0];	539	return $grp->result () if $_[0];
426	my $now = time;	540	my $now = time;
427	my $hash1 = join ":", (stat _)[0,1,3,7,9];	541	my $hash1 = join ":", (stat _)[0,1,3,7,9];
428		542
429	# read the directory entries	543	# read the directory entries
		544	aioreq_pri $pri;
430	add $grp aio_readdir $path, sub {	545	add $grp aio_readdir $path, sub {
431	my $entries = shift	546	my $entries = shift
432	or return $grp->result ();	547	or return $grp->result ();
433		548
434	# stat the dir another time	549	# stat the dir another time
		550	aioreq_pri $pri;
435	add $grp aio_stat $path, sub {	551	add $grp aio_stat $path, sub {
436	my $hash2 = join ":", (stat _)[0,1,3,7,9];	552	my $hash2 = join ":", (stat _)[0,1,3,7,9];
437		553
438	my $ndirs;	554	my $ndirs;
439		555
…		…
454	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],	570	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
455	@$entries];	571	@$entries];
456		572
457	my (@dirs, @nondirs);	573	my (@dirs, @nondirs);
458		574
459	my ($statcb, $schedcb);
460	my $nreq = 0;
461
462	my $statgrp = add $grp aio_group;	575	my $statgrp = add $grp aio_group sub {
		576	$grp->result (\@dirs, \@nondirs);
		577	};
463		578
464	$schedcb = sub {	579	limit $statgrp $maxreq;
465	if (@$entries) {	580	feed $statgrp sub {
466	if ($nreq < $maxreq) {	581	return unless @$entries;
467	my $ent = pop @$entries;	582	my $entry = pop @$entries;
		583
		584	aioreq_pri $pri;
		585	add $statgrp aio_stat "$path/$entry/.", sub {
		586	if ($_[0] < 0) {
		587	push @nondirs, $entry;
		588	} else {
		589	# need to check for real directory
		590	aioreq_pri $pri;
		591	add $statgrp aio_lstat "$path/$entry", sub {
		592	if (-d _) {
		593	push @dirs, $entry;
		594
		595	unless (--$ndirs) {
		596	push @nondirs, @$entries;
		597	feed $statgrp;
		598	}
		599	} else {
		600	push @nondirs, $entry;
		601	}
468	$nreq++;	602	}
469	add $statgrp aio_stat "$path/$ent/.", sub { $statcb->($_[0], $ent) };
470	}	603	}
471	} elsif (!$nreq) {
472	# finished
473	$statgrp->cancel;
474	undef $statcb;
475	undef $schedcb;
476	$grp->result (\@dirs, \@nondirs);
477	}	604	};
478	};	605	};
479	$statcb = sub {
480	my ($status, $entry) = @_;
481
482	if ($status < 0) {
483	$nreq--;
484	push @nondirs, $entry;
485	&$schedcb;
486	} else {
487	# need to check for real directory
488	add $grp aio_lstat "$path/$entry", sub {
489	$nreq--;
490
491	if (-d _) {
492	push @dirs, $entry;
493
494	if (!--$ndirs) {
495	push @nondirs, @$entries;
496	$entries = [];
497	}
498	} else {
499	push @nondirs, $entry;
500	}
501
502	&$schedcb;
503	}
504	}
505	};
506
507	&$schedcb while @$entries && $nreq < $maxreq;
508	};	606	};
509	};	607	};
510	};	608	};
511		609
512	$grp	610	$grp
…		…
525	If this call isn't available because your OS lacks it or it couldn't be	623	If this call isn't available because your OS lacks it or it couldn't be
526	detected, it will be emulated by calling C<fsync> instead.	624	detected, it will be emulated by calling C<fsync> instead.
527		625
528	=item aio_group $callback->(...)	626	=item aio_group $callback->(...)
529		627
530	[EXPERIMENTAL]
531
532	This is a very special aio request: Instead of doing something, it is a	628	This is a very special aio request: Instead of doing something, it is a
533	container for other aio requests, which is useful if you want to bundle	629	container for other aio requests, which is useful if you want to bundle
534	many requests into a single, composite, request.	630	many requests into a single, composite, request with a definite callback
		631	and the ability to cancel the whole request with its subrequests.
535		632
536	Returns an object of class L<IO::AIO::GRP>. See its documentation below	633	Returns an object of class L<IO::AIO::GRP>. See its documentation below
537	for more info.	634	for more info.
538		635
539	Example:	636	Example:
…		…
558	phase and still requires a worker thread. Thus, the callback will not	655	phase and still requires a worker thread. Thus, the callback will not
559	be executed immediately but only after other requests in the queue have	656	be executed immediately but only after other requests in the queue have
560	entered their execution phase. This can be used to measure request	657	entered their execution phase. This can be used to measure request
561	latency.	658	latency.
562		659
563	=item IO::AIO::aio_sleep $fractional_seconds, $callback->() NOT EXPORTED	660	=item IO::AIO::aio_busy $fractional_seconds, $callback->() NOT EXPORTED
564		661
565	Mainly used for debugging and benchmarking, this aio request puts one of	662	Mainly used for debugging and benchmarking, this aio request puts one of
566	the request workers to sleep for the given time.	663	the request workers to sleep for the given time.
567		664
568	While it is theoretically handy to have simple I/O scheduling requests	665	While it is theoretically handy to have simple I/O scheduling requests
569	like sleep and file handle readable/writable, the overhead this creates	666	like sleep and file handle readable/writable, the overhead this creates is
570	is immense, so do not use this function except to put your application	667	immense (it blocks a thread for a long time) so do not use this function
571	under artificial I/O pressure.	668	except to put your application under artificial I/O pressure.
572		669
573	=back	670	=back
574		671
575	=head2 IO::AIO::REQ CLASS	672	=head2 IO::AIO::REQ CLASS
576		673
577	All non-aggregate C<aio_*> functions return an object of this class when	674	All non-aggregate C<aio_*> functions return an object of this class when
578	called in non-void context.	675	called in non-void context.
579
580	A request always moves through the following five states in its lifetime,
581	in order: B<ready> (request has been created, but has not been executed
582	yet), B<execute> (request is currently being executed), B<pending>
583	(request has been executed but callback has not been called yet),
584	B<result> (results are being processed synchronously, includes calling the
585	callback) and B<done> (request has reached the end of its lifetime and
586	holds no resources anymore).
587		676
588	=over 4	677	=over 4
589		678
590	=item cancel $req	679	=item cancel $req
591		680
…		…
645	=item * They can also can also be added to other IO::AIO::GRP objects.	734	=item * They can also can also be added to other IO::AIO::GRP objects.
646		735
647	=item * You must not add requests to a group from within the group callback (or	736	=item * You must not add requests to a group from within the group callback (or
648	any later time).	737	any later time).
649		738
650	=item * This does not harmonise well with C<max_outstanding>, so best do
651	not combine C<aio_group> with it. Groups and feeders are recommended for
652	this kind of concurrency-limiting.
653
654	=back	739	=back
655		740
656	Their lifetime, simplified, looks like this: when they are empty, they	741	Their lifetime, simplified, looks like this: when they are empty, they
657	will finish very quickly. If they contain only requests that are in the	742	will finish very quickly. If they contain only requests that are in the
658	C<done> state, they will also finish. Otherwise they will continue to	743	C<done> state, they will also finish. Otherwise they will continue to
…		…
673	be added, including other groups, as long as you do not create circular	758	be added, including other groups, as long as you do not create circular
674	dependencies.	759	dependencies.
675		760
676	Returns all its arguments.	761	Returns all its arguments.
677		762
		763	=item $grp->cancel_subs
		764
		765	Cancel all subrequests and clears any feeder, but not the group request
		766	itself. Useful when you queued a lot of events but got a result early.
		767
678	=item $grp->result (...)	768	=item $grp->result (...)
679		769
680	Set the result value(s) that will be passed to the group callback when all	770	Set the result value(s) that will be passed to the group callback when all
681	subrequests have finished. By default, no argument will be passed.	771	subrequests have finished and set thre groups errno to the current value
		772	of errno (just like calling C<errno> without an error number). By default,
		773	no argument will be passed and errno is zero.
		774
		775	=item $grp->errno ([$errno])
		776
		777	Sets the group errno value to C<$errno>, or the current value of errno
		778	when the argument is missing.
		779
		780	Every aio request has an associated errno value that is restored when
		781	the callback is invoked. This method lets you change this value from its
		782	default (0).
		783
		784	Calling C<result> will also set errno, so make sure you either set C<$!>
		785	before the call to C<result>, or call c<errno> after it.
682		786
683	=item feed $grp $callback->($grp)	787	=item feed $grp $callback->($grp)
684
685	[VERY EXPERIMENTAL]
686		788
687	Sets a feeder/generator on this group: every group can have an attached	789	Sets a feeder/generator on this group: every group can have an attached
688	generator that generates requests if idle. The idea behind this is that,	790	generator that generates requests if idle. The idea behind this is that,
689	although you could just queue as many requests as you want in a group,	791	although you could just queue as many requests as you want in a group,
690	this might starve other requests for a potentially long time. For	792	this might starve other requests for a potentially long time. For
…		…
744		846
745	Process all outstanding events on the result pipe. You have to call this	847	Process all outstanding events on the result pipe. You have to call this
746	regularly. Returns the number of events processed. Returns immediately	848	regularly. Returns the number of events processed. Returns immediately
747	when no events are outstanding.	849	when no events are outstanding.
748		850
		851	If not all requests were processed for whatever reason, the filehandle
		852	will still be ready when C<poll_cb> returns.
		853
749	Example: Install an Event watcher that automatically calls	854	Example: Install an Event watcher that automatically calls
750	IO::AIO::poll_cb with high priority:	855	IO::AIO::poll_cb with high priority:
751		856
752	Event->io (fd => IO::AIO::poll_fileno,	857	Event->io (fd => IO::AIO::poll_fileno,
753	poll => 'r', async => 1,	858	poll => 'r', async => 1,
754	cb => \&IO::AIO::poll_cb);	859	cb => \&IO::AIO::poll_cb);
755		860
		861	=item IO::AIO::poll_some $max_requests
		862
		863	Similar to C<poll_cb>, but only processes up to C<$max_requests> requests
		864	at a time.
		865
		866	Useful if you want to ensure some level of interactiveness when perl is
		867	not fast enough to process all requests in time.
		868
		869	Example: Install an Event watcher that automatically calls
		870	IO::AIO::poll_some with low priority, to ensure that other parts of the
		871	program get the CPU sometimes even under high AIO load.
		872
		873	Event->io (fd => IO::AIO::poll_fileno,
		874	poll => 'r', nice => 1,
		875	cb => sub { IO::AIO::poll_some 256 });
		876
756	=item IO::AIO::poll_wait	877	=item IO::AIO::poll_wait
757		878
758	Wait till the result filehandle becomes ready for reading (simply does a	879	Wait till the result filehandle becomes ready for reading (simply does a
759	C<select> on the filehandle. This is useful if you want to synchronously wait	880	C<select> on the filehandle. This is useful if you want to synchronously wait
760	for some requests to finish).	881	for some requests to finish).
761		882
762	See C<nreqs> for an example.	883	See C<nreqs> for an example.
763		884
764	=item IO::AIO::nreqs	885	=item IO::AIO::nreqs
765		886
766	Returns the number of requests currently outstanding (i.e. for which their	887	Returns the number of requests currently in the ready, execute or pending
767	callback has not been invoked yet).	888	states (i.e. for which their callback has not been invoked yet).
768		889
769	Example: wait till there are no outstanding requests anymore:	890	Example: wait till there are no outstanding requests anymore:
770		891
771	IO::AIO::poll_wait, IO::AIO::poll_cb	892	IO::AIO::poll_wait, IO::AIO::poll_cb
772	while IO::AIO::nreqs;	893	while IO::AIO::nreqs;
		894
		895	=item IO::AIO::nready
		896
		897	Returns the number of requests currently in the ready state (not yet
		898	executed).
		899
		900	=item IO::AIO::npending
		901
		902	Returns the number of requests currently in the pending state (executed,
		903	but not yet processed by poll_cb).
773		904
774	=item IO::AIO::flush	905	=item IO::AIO::flush
775		906
776	Wait till all outstanding AIO requests have been handled.	907	Wait till all outstanding AIO requests have been handled.
777		908
…		…
819	This module automatically runs C<max_parallel 0> at program end, to ensure	950	This module automatically runs C<max_parallel 0> at program end, to ensure
820	that all threads are killed and that there are no outstanding requests.	951	that all threads are killed and that there are no outstanding requests.
821		952
822	Under normal circumstances you don't need to call this function.	953	Under normal circumstances you don't need to call this function.
823		954
824	=item $oldnreqs = IO::AIO::max_outstanding $nreqs	955	=item $oldmaxreqs = IO::AIO::max_outstanding $maxreqs
825		956
826	[DEPRECATED]	957	This is a very bad function to use in interactive programs because it
		958	blocks, and a bad way to reduce concurrency because it is inexact: Better
		959	use an C<aio_group> together with a feed callback.
827		960
828	Sets the maximum number of outstanding requests to C<$nreqs>. If you	961	Sets the maximum number of outstanding requests to C<$nreqs>. If you
829	try to queue up more than this number of requests, the caller will block until	962	to queue up more than this number of requests, the next call to the
830	some requests have been handled.	963	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
		964	function will block until the limit is no longer exceeded.
831		965
832	The default is very large, so normally there is no practical limit. If you	966	The default value is very large, so there is no practical limit on the
833	queue up many requests in a loop it often improves speed if you set	967	number of outstanding requests.
834	this to a relatively low number, such as C<100>.
835		968
836	This function does not work well together with C<aio_group>'s, and their	969	You can still queue as many requests as you want. Therefore,
837	feeder interface is better suited to limiting concurrency, so do not use	970	C<max_oustsanding> is mainly useful in simple scripts (with low values) or
838	this function.	971	as a stop gap to shield against fatal memory overflow (with large values).
839
840	Under normal circumstances you don't need to call this function.
841		972
842	=back	973	=back
843		974
844	=cut	975	=cut
845		976
…		…
860	}	991	}
861		992
862	min_parallel 8;	993	min_parallel 8;
863		994
864	END {	995	END {
865	max_parallel 0;	996	min_parallel 1;
866	}	997	flush;
		998	};
867		999
868	1;	1000	1;
869		1001
870	=head2 FORK BEHAVIOUR	1002	=head2 FORK BEHAVIOUR
871		1003
872	This module should do "the right thing" when the process using it forks:	1004	This module should do "the right thing" when the process using it forks:
873		1005
874	Before the fork, IO::AIO enters a quiescent state where no requests	1006	Before the fork, IO::AIO enters a quiescent state where no requests
875	can be added in other threads and no results will be processed. After	1007	can be added in other threads and no results will be processed. After
876	the fork the parent simply leaves the quiescent state and continues	1008	the fork the parent simply leaves the quiescent state and continues
877	request/result processing, while the child clears the request/result	1009	request/result processing, while the child frees the request/result queue
878	queue (so the requests started before the fork will only be handled in	1010	(so that the requests started before the fork will only be handled in the
879	the parent). Threads will be started on demand until the limit ste in the	1011	parent). Threads will be started on demand until the limit set in the
880	parent process has been reached again.	1012	parent process has been reached again.
881		1013
882	In short: the parent will, after a short pause, continue as if fork had	1014	In short: the parent will, after a short pause, continue as if fork had
883	not been called, while the child will act as if IO::AIO has not been used	1015	not been called, while the child will act as if IO::AIO has not been used
884	yet.	1016	yet.
885		1017
886	=head2 MEMORY USAGE	1018	=head2 MEMORY USAGE
887		1019
		1020	Per-request usage:
		1021
888	Each aio request uses - depending on your architecture - around 128 bytes	1022	Each aio request uses - depending on your architecture - around 100-200
889	of memory. In addition, stat requests need a stat buffer (possibly a few	1023	bytes of memory. In addition, stat requests need a stat buffer (possibly
890	hundred bytes). Perl scalars and other data passed into aio requests will	1024	a few hundred bytes), readdir requires a result buffer and so on. Perl
891	also be locked.	1025	scalars and other data passed into aio requests will also be locked and
		1026	will consume memory till the request has entered the done state.
892		1027
893	This is now awfully much, so queuing lots of requests is not usually a	1028	This is now awfully much, so queuing lots of requests is not usually a
894	problem.	1029	problem.
895		1030
896	Each thread needs a stack area which is usually around 16k, sometimes much	1031	Per-thread usage:
897	larger, depending on the OS.	1032
		1033	In the execution phase, some aio requests require more memory for
		1034	temporary buffers, and each thread requires a stack and other data
		1035	structures (usually around 16k-128k, depending on the OS).
		1036
		1037	=head1 KNOWN BUGS
		1038
		1039	Known bugs will be fixed in the next release.
898		1040
899	=head1 SEE ALSO	1041	=head1 SEE ALSO
900		1042
901	L<Coro::AIO>.	1043	L<Coro::AIO>.
902		1044

Diff Legend

-–
+Removed lines
-+
+Added lines
-<
+Changed lines
->
+Changed lines

Comparing IO-AIO/AIO.pm (file contents): Revision 1.68 by root, Tue Oct 24 03:17:39 2006 UTC vs. Revision 1.84 by root, Sat Oct 28 00:17:30 2006 UTC

Diff Legend

Comparing IO-AIO/AIO.pm (file contents):
Revision 1.68 by root, Tue Oct 24 03:17:39 2006 UTC vs.
Revision 1.84 by root, Sat Oct 28 00:17:30 2006 UTC