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

Comparing IO-AIO/AIO.pm (file contents):
Revision 1.62 by root, Sun Oct 22 21:13:47 2006 UTC vs.
Revision 1.85 by root, Sat Oct 28 01:40:30 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
		56	Asynchronous means that operations that can normally block your program
		57	(e.g. reading from disk) will be done asynchronously: the operation
		58	will still block, but you can do something else in the meantime. This
		59	is extremely useful for programs that need to stay interactive even
		60	when doing heavy I/O (GUI programs, high performance network servers
		61	etc.), but can also be used to easily do operations in parallel that are
		62	normally done sequentially, e.g. stat'ing many files, which is much faster
		63	on a RAID volume or over NFS when you do a number of stat operations
		64	concurrently.
		65
		66	While this works on all types of file descriptors (for example sockets),
		67	using these functions on file descriptors that support nonblocking
		68	operation (again, sockets, pipes etc.) is very inefficient. Use an event
		69	loop for that (such as the L<Event\|Event> module): IO::AIO will naturally
		70	fit into such an event loop itself.
		71
55	Currently, a number of threads are started that execute your read/writes	72	In this version, a number of threads are started that execute your
56	and signal their completion. You don't need thread support in your libc or	73	requests and signal their completion. You don't need thread support
57	perl, and the threads created by this module will not be visible to the	74	in perl, and the threads created by this module will not be visible
58	pthreads library. In the future, this module might make use of the native	75	to perl. In the future, this module might make use of the native aio
59	aio functions available on many operating systems. However, they are often	76	functions available on many operating systems. However, they are often
60	not well-supported (Linux doesn't allow them on normal files currently,	77	not well-supported or restricted (GNU/Linux doesn't allow them on normal
61	for example), and they would only support aio_read and aio_write, so the	78	files currently, for example), and they would only support aio_read and
62	remaining functionality would have to be implemented using threads anyway.	79	aio_write, so the remaining functionality would have to be implemented
		80	using threads anyway.
63		81
64	Although the module will work with in the presence of other threads, it is	82	Although the module will work with in the presence of other (Perl-)
65	currently not reentrant, so use appropriate locking yourself, always call	83	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	84	locking yourself, always call C<poll_cb> from within the same thread, or
67	C<aio_> functions) recursively.	85	never call C<poll_cb> (or other C<aio_> functions) recursively.
		86
		87	=head1 REQUEST ANATOMY AND LIFETIME
		88
		89	Every C<aio_*> function creates a request. which is a C data structure not
		90	directly visible to Perl.
		91
		92	If called in non-void context, every request function returns a Perl
		93	object representing the request. In void context, nothing is returned,
		94	which saves a bit of memory.
		95
		96	The perl object is a fairly standard ref-to-hash object. The hash contents
		97	are not used by IO::AIO so you are free to store anything you like in it.
		98
		99	During their existance, aio requests travel through the following states,
		100	in order:
		101
		102	=over 4
		103
		104	=item ready
		105
		106	Immediately after a request is created it is put into the ready state,
		107	waiting for a thread to execute it.
		108
		109	=item execute
		110
		111	A thread has accepted the request for processing and is currently
		112	executing it (e.g. blocking in read).
		113
		114	=item pending
		115
		116	The request has been executed and is waiting for result processing.
		117
		118	While request submission and execution is fully asynchronous, result
		119	processing is not and relies on the perl interpreter calling C<poll_cb>
		120	(or another function with the same effect).
		121
		122	=item result
		123
		124	The request results are processed synchronously by C<poll_cb>.
		125
		126	The C<poll_cb> function will process all outstanding aio requests by
		127	calling their callbacks, freeing memory associated with them and managing
		128	any groups they are contained in.
		129
		130	=item done
		131
		132	Request has reached the end of its lifetime and holds no resources anymore
		133	(except possibly for the Perl object, but its connection to the actual
		134	aio request is severed and calling its methods will either do nothing or
		135	result in a runtime error).
68		136
69	=cut	137	=cut
70		138
71	package IO::AIO;	139	package IO::AIO;
72		140
…		…
76	use base 'Exporter';	144	use base 'Exporter';
77		145
78	BEGIN {	146	BEGIN {
79	our $VERSION = '2.0';	147	our $VERSION = '2.0';
80		148
81	our @EXPORT = qw(aio_sendfile aio_read aio_write aio_open aio_close aio_stat	149	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	150	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	151	aio_fsync aio_fdatasync aio_readahead aio_rename aio_link aio_move
84	aio_group);	152	aio_copy aio_group aio_nop aio_mknod);
85	our @EXPORT_OK = qw(poll_fileno poll_cb min_parallel max_parallel max_outstanding nreqs);	153	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
		154	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
		155	min_parallel max_parallel nreqs nready npending);
86		156
87	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';	157	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';
88		158
89	require XSLoader;	159	require XSLoader;
90	XSLoader::load ("IO::AIO", $VERSION);	160	XSLoader::load ("IO::AIO", $VERSION);
…		…
121	environment, d) use Glib::filename_from_unicode on unicode filenames or e)	191	environment, d) use Glib::filename_from_unicode on unicode filenames or e)
122	use something else.	192	use something else.
123		193
124	=over 4	194	=over 4
125		195
		196	=item $prev_pri = aioreq_pri [$pri]
		197
		198	Returns the priority value that would be used for the next request and, if
		199	C<$pri> is given, sets the priority for the next aio request.
		200
		201	The default priority is C<0>, the minimum and maximum priorities are C<-4>
		202	and C<4>, respectively. Requests with higher priority will be serviced
		203	first.
		204
		205	The priority will be reset to C<0> after each call to one of the C<aio_*>
		206	functions.
		207
		208	Example: open a file with low priority, then read something from it with
		209	higher priority so the read request is serviced before other low priority
		210	open requests (potentially spamming the cache):
		211
		212	aioreq_pri -3;
		213	aio_open ..., sub {
		214	return unless $_[0];
		215
		216	aioreq_pri -2;
		217	aio_read $_[0], ..., sub {
		218	...
		219	};
		220	};
		221
		222	=item aioreq_nice $pri_adjust
		223
		224	Similar to C<aioreq_pri>, but subtracts the given value from the current
		225	priority, so effects are cumulative.
		226
126	=item aio_open $pathname, $flags, $mode, $callback->($fh)	227	=item aio_open $pathname, $flags, $mode, $callback->($fh)
127		228
128	Asynchronously open or create a file and call the callback with a newly	229	Asynchronously open or create a file and call the callback with a newly
129	created filehandle for the file.	230	created filehandle for the file.
130		231
…		…
179		280
180	aio_read $fh, 7, 15, $buffer, 0, sub {	281	aio_read $fh, 7, 15, $buffer, 0, sub {
181	$_[0] > 0 or die "read error: $!";	282	$_[0] > 0 or die "read error: $!";
182	print "read $_[0] bytes: <$buffer>\n";	283	print "read $_[0] bytes: <$buffer>\n";
183	};	284	};
184
185	=item aio_move $srcpath, $dstpath, $callback->($status)
186
187	[EXPERIMENTAL due to internal aio_group use]
188
189	Try to move the I<file> (directories not supported as either source or
190	destination) from C<$srcpath> to C<$dstpath> and call the callback with
191	the C<0> (error) or C<-1> ok.
192
193	This is a composite request that tries to rename(2) the file first. If
194	rename files with C<EXDEV>, it creates the destination file with mode 0200
195	and copies the contents of the source file into it using C<aio_sendfile>,
196	followed by restoring atime, mtime, access mode and uid/gid, in that
197	order, and unlinking the C<$srcpath>.
198
199	If an error occurs, the partial destination file will be unlinked, if
200	possible, except when setting atime, mtime, access mode and uid/gid, where
201	errors are being ignored.
202
203	=cut
204
205	sub aio_move($$$) {
206	my ($src, $dst, $cb) = @_;
207
208	my $grp = aio_group $cb;
209
210	add $grp aio_rename $src, $dst, sub {
211	if ($_[0] && $! == EXDEV) {
212	add $grp aio_open $src, O_RDONLY, 0, sub {
213	if (my $src_fh = $_[0]) {
214	my @stat = stat $src_fh;
215
216	add $grp aio_open $dst, O_WRONLY, 0200, sub {
217	if (my $dst_fh = $_[0]) {
218	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
219	close $src_fh;
220
221	if ($_[0] == $stat[7]) {
222	utime $stat[8], $stat[9], $dst;
223	chmod $stat[2] & 07777, $dst_fh;
224	chown $stat[4], $stat[5], $dst_fh;
225	close $dst_fh;
226
227	add $grp aio_unlink $src, sub {
228	$grp->result ($_[0]);
229	};
230	} else {
231	my $errno = $!;
232	add $grp aio_unlink $dst, sub {
233	$! = $errno;
234	$grp->result (-1);
235	};
236	}
237	};
238	} else {
239	$grp->result (-1);
240	}
241	},
242
243	} else {
244	$grp->result (-1);
245	}
246	};
247	} else {
248	$grp->result ($_[0]);
249	}
250	};
251
252	$grp
253	}
254		285
255	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)	286	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
256		287
257	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts	288	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
258	reading at byte offset C<$in_offset>, and starts writing at the current	289	reading at byte offset C<$in_offset>, and starts writing at the current
…		…
314	=item aio_unlink $pathname, $callback->($status)	345	=item aio_unlink $pathname, $callback->($status)
315		346
316	Asynchronously unlink (delete) a file and call the callback with the	347	Asynchronously unlink (delete) a file and call the callback with the
317	result code.	348	result code.
318		349
		350	=item aio_mknod $path, $mode, $dev, $callback->($status)
		351
		352	Asynchronously create a device node (or fifo). See mknod(2).
		353
		354	The only portable (POSIX) way of calling this function is:
		355
		356	aio_mknod $path, IO::AIO::S_IFIFO \| $mode, 0, sub { ...
		357
319	=item aio_link $srcpath, $dstpath, $callback->($status)	358	=item aio_link $srcpath, $dstpath, $callback->($status)
320		359
321	Asynchronously create a new link to the existing object at C<$srcpath> at	360	Asynchronously create a new link to the existing object at C<$srcpath> at
322	the path C<$dstpath> and call the callback with the result code.	361	the path C<$dstpath> and call the callback with the result code.
323		362
…		…
343	sorted, and will B<NOT> include the C<.> and C<..> entries.	382	sorted, and will B<NOT> include the C<.> and C<..> entries.
344		383
345	The callback a single argument which is either C<undef> or an array-ref	384	The callback a single argument which is either C<undef> or an array-ref
346	with the filenames.	385	with the filenames.
347		386
		387	=item aio_copy $srcpath, $dstpath, $callback->($status)
		388
		389	Try to copy the I<file> (directories not supported as either source or
		390	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		391	the C<0> (error) or C<-1> ok.
		392
		393	This is a composite request that it creates the destination file with
		394	mode 0200 and copies the contents of the source file into it using
		395	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
		396	uid/gid, in that order.
		397
		398	If an error occurs, the partial destination file will be unlinked, if
		399	possible, except when setting atime, mtime, access mode and uid/gid, where
		400	errors are being ignored.
		401
		402	=cut
		403
		404	sub aio_copy($$;$) {
		405	my ($src, $dst, $cb) = @_;
		406
		407	my $pri = aioreq_pri;
		408	my $grp = aio_group $cb;
		409
		410	aioreq_pri $pri;
		411	add $grp aio_open $src, O_RDONLY, 0, sub {
		412	if (my $src_fh = $_[0]) {
		413	my @stat = stat $src_fh;
		414
		415	aioreq_pri $pri;
		416	add $grp aio_open $dst, O_CREAT \| O_WRONLY \| O_TRUNC, 0200, sub {
		417	if (my $dst_fh = $_[0]) {
		418	aioreq_pri $pri;
		419	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
		420	if ($_[0] == $stat[7]) {
		421	$grp->result (0);
		422	close $src_fh;
		423
		424	# those should not normally block. should. should.
		425	utime $stat[8], $stat[9], $dst;
		426	chmod $stat[2] & 07777, $dst_fh;
		427	chown $stat[4], $stat[5], $dst_fh;
		428	close $dst_fh;
		429	} else {
		430	$grp->result (-1);
		431	close $src_fh;
		432	close $dst_fh;
		433
		434	aioreq $pri;
		435	add $grp aio_unlink $dst;
		436	}
		437	};
		438	} else {
		439	$grp->result (-1);
		440	}
		441	},
		442
		443	} else {
		444	$grp->result (-1);
		445	}
		446	};
		447
		448	$grp
		449	}
		450
		451	=item aio_move $srcpath, $dstpath, $callback->($status)
		452
		453	Try to move the I<file> (directories not supported as either source or
		454	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		455	the C<0> (error) or C<-1> ok.
		456
		457	This is a composite request that tries to rename(2) the file first. If
		458	rename files with C<EXDEV>, it copies the file with C<aio_copy> and, if
		459	that is successful, unlinking the C<$srcpath>.
		460
		461	=cut
		462
		463	sub aio_move($$;$) {
		464	my ($src, $dst, $cb) = @_;
		465
		466	my $pri = aioreq_pri;
		467	my $grp = aio_group $cb;
		468
		469	aioreq_pri $pri;
		470	add $grp aio_rename $src, $dst, sub {
		471	if ($_[0] && $! == EXDEV) {
		472	aioreq_pri $pri;
		473	add $grp aio_copy $src, $dst, sub {
		474	$grp->result ($_[0]);
		475
		476	if (!$_[0]) {
		477	aioreq_pri $pri;
		478	add $grp aio_unlink $src;
		479	}
		480	};
		481	} else {
		482	$grp->result ($_[0]);
		483	}
		484	};
		485
		486	$grp
		487	}
		488
348	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	489	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
349		490
350	[EXPERIMENTAL due to internal aio_group use]
351
352	Scans a directory (similar to C<aio_readdir>) but additionally tries to	491	Scans a directory (similar to C<aio_readdir>) but additionally tries to
353	separate the entries of directory C<$path> into two sets of names, ones	492	efficiently separate the entries of directory C<$path> into two sets of
354	you can recurse into (directories or links to them), and ones you cannot	493	names, directories you can recurse into (directories), and ones you cannot
355	recurse into (everything else).	494	recurse into (everything else, including symlinks to directories).
356		495
357	C<aio_scandir> is a composite request that creates of many sub requests_	496	C<aio_scandir> is a composite request that creates of many sub requests_
358	C<$maxreq> specifies the maximum number of outstanding aio requests that	497	C<$maxreq> specifies the maximum number of outstanding aio requests that
359	this function generates. If it is C<< <= 0 >>, then a suitable default	498	this function generates. If it is C<< <= 0 >>, then a suitable default
360	will be chosen (currently 6).	499	will be chosen (currently 4).
361		500
362	On error, the callback is called without arguments, otherwise it receives	501	On error, the callback is called without arguments, otherwise it receives
363	two array-refs with path-relative entry names.	502	two array-refs with path-relative entry names.
364		503
365	Example:	504	Example:
…		…
402	=cut	541	=cut
403		542
404	sub aio_scandir($$$) {	543	sub aio_scandir($$$) {
405	my ($path, $maxreq, $cb) = @_;	544	my ($path, $maxreq, $cb) = @_;
406		545
		546	my $pri = aioreq_pri;
		547
407	my $grp = aio_group $cb;	548	my $grp = aio_group $cb;
408		549
409	$maxreq = 6 if $maxreq <= 0;	550	$maxreq = 4 if $maxreq <= 0;
410		551
411	# stat once	552	# stat once
		553	aioreq_pri $pri;
412	add $grp aio_stat $path, sub {	554	add $grp aio_stat $path, sub {
413	return $grp->result () if $_[0];	555	return $grp->result () if $_[0];
414	my $now = time;	556	my $now = time;
415	my $hash1 = join ":", (stat _)[0,1,3,7,9];	557	my $hash1 = join ":", (stat _)[0,1,3,7,9];
416		558
417	# read the directory entries	559	# read the directory entries
		560	aioreq_pri $pri;
418	add $grp aio_readdir $path, sub {	561	add $grp aio_readdir $path, sub {
419	my $entries = shift	562	my $entries = shift
420	or return $grp->result ();	563	or return $grp->result ();
421		564
422	# stat the dir another time	565	# stat the dir another time
		566	aioreq_pri $pri;
423	add $grp aio_stat $path, sub {	567	add $grp aio_stat $path, sub {
424	my $hash2 = join ":", (stat _)[0,1,3,7,9];	568	my $hash2 = join ":", (stat _)[0,1,3,7,9];
425		569
426	my $ndirs;	570	my $ndirs;
427		571
…		…
442	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],	586	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
443	@$entries];	587	@$entries];
444		588
445	my (@dirs, @nondirs);	589	my (@dirs, @nondirs);
446		590
447	my ($statcb, $schedcb);
448	my $nreq = 0;
449
450	my $statgrp = add $grp aio_group;	591	my $statgrp = add $grp aio_group sub {
		592	$grp->result (\@dirs, \@nondirs);
		593	};
451		594
452	$schedcb = sub {	595	limit $statgrp $maxreq;
453	if (@$entries) {	596	feed $statgrp sub {
454	if ($nreq < $maxreq) {	597	return unless @$entries;
455	my $ent = pop @$entries;	598	my $entry = pop @$entries;
		599
		600	aioreq_pri $pri;
		601	add $statgrp aio_stat "$path/$entry/.", sub {
		602	if ($_[0] < 0) {
		603	push @nondirs, $entry;
		604	} else {
		605	# need to check for real directory
		606	aioreq_pri $pri;
		607	add $statgrp aio_lstat "$path/$entry", sub {
		608	if (-d _) {
		609	push @dirs, $entry;
		610
		611	unless (--$ndirs) {
		612	push @nondirs, @$entries;
		613	feed $statgrp;
		614	}
		615	} else {
		616	push @nondirs, $entry;
		617	}
456	$nreq++;	618	}
457	add $statgrp aio_stat "$path/$ent/.", sub { $statcb->($_[0], $ent) };
458	}	619	}
459	} elsif (!$nreq) {
460	# finished
461	$statgrp->cancel;
462	undef $statcb;
463	undef $schedcb;
464	$grp->result (\@dirs, \@nondirs);
465	}	620	};
466	};	621	};
467	$statcb = sub {
468	my ($status, $entry) = @_;
469
470	if ($status < 0) {
471	$nreq--;
472	push @nondirs, $entry;
473	&$schedcb;
474	} else {
475	# need to check for real directory
476	add $grp aio_lstat "$path/$entry", sub {
477	$nreq--;
478
479	if (-d _) {
480	push @dirs, $entry;
481
482	if (!--$ndirs) {
483	push @nondirs, @$entries;
484	$entries = [];
485	}
486	} else {
487	push @nondirs, $entry;
488	}
489
490	&$schedcb;
491	}
492	}
493	};
494
495	&$schedcb while @$entries && $nreq < $maxreq;
496	};	622	};
497	};	623	};
498	};	624	};
499		625
500	$grp	626	$grp
…		…
513	If this call isn't available because your OS lacks it or it couldn't be	639	If this call isn't available because your OS lacks it or it couldn't be
514	detected, it will be emulated by calling C<fsync> instead.	640	detected, it will be emulated by calling C<fsync> instead.
515		641
516	=item aio_group $callback->(...)	642	=item aio_group $callback->(...)
517		643
518	[EXPERIMENTAL]
519
520	This is a very special aio request: Instead of doing something, it is a	644	This is a very special aio request: Instead of doing something, it is a
521	container for other aio requests, which is useful if you want to bundle	645	container for other aio requests, which is useful if you want to bundle
522	many requests into a single, composite, request.	646	many requests into a single, composite, request with a definite callback
		647	and the ability to cancel the whole request with its subrequests.
523		648
524	Returns an object of class L<IO::AIO::GRP>. See its documentation below	649	Returns an object of class L<IO::AIO::GRP>. See its documentation below
525	for more info.	650	for more info.
526		651
527	Example:	652	Example:
…		…
533	add $grp	658	add $grp
534	(aio_stat ...),	659	(aio_stat ...),
535	(aio_stat ...),	660	(aio_stat ...),
536	...;	661	...;
537		662
		663	=item aio_nop $callback->()
		664
		665	This is a special request - it does nothing in itself and is only used for
		666	side effects, such as when you want to add a dummy request to a group so
		667	that finishing the requests in the group depends on executing the given
		668	code.
		669
		670	While this request does nothing, it still goes through the execution
		671	phase and still requires a worker thread. Thus, the callback will not
		672	be executed immediately but only after other requests in the queue have
		673	entered their execution phase. This can be used to measure request
		674	latency.
		675
538	=item IO::AIO::aio_sleep $fractional_seconds, $callback->() NOT EXPORTED	676	=item IO::AIO::aio_busy $fractional_seconds, $callback->() NOT EXPORTED
539		677
540	Mainly used for debugging and benchmarking, this aio request puts one of	678	Mainly used for debugging and benchmarking, this aio request puts one of
541	the request workers to sleep for the given time.	679	the request workers to sleep for the given time.
542		680
543	While it is theoretically handy to have simple I/O scheduling requests	681	While it is theoretically handy to have simple I/O scheduling requests
544	like sleep and file handle readable/writable, the overhead this creates	682	like sleep and file handle readable/writable, the overhead this creates is
545	is immense, so do not use this function except to put your application	683	immense (it blocks a thread for a long time) so do not use this function
546	under artificial I/O pressure.	684	except to put your application under artificial I/O pressure.
547		685
548	=back	686	=back
549		687
550	=head2 IO::AIO::REQ CLASS	688	=head2 IO::AIO::REQ CLASS
551		689
552	All non-aggregate C<aio_*> functions return an object of this class when	690	All non-aggregate C<aio_*> functions return an object of this class when
553	called in non-void context.	691	called in non-void context.
554		692
555	A request always moves through the following five states in its lifetime,
556	in order: B<ready> (request has been created, but has not been executed
557	yet), B<execute> (request is currently being executed), B<pending>
558	(request has been executed but callback has not been called yet),
559	B<result> (results are being processed synchronously, includes calling the
560	callback) and B<done> (request has reached the end of its lifetime and
561	holds no resources anymore).
562
563	=over 4	693	=over 4
564		694
565	=item $req->cancel	695	=item cancel $req
566		696
567	Cancels the request, if possible. Has the effect of skipping execution	697	Cancels the request, if possible. Has the effect of skipping execution
568	when entering the B<execute> state and skipping calling the callback when	698	when entering the B<execute> state and skipping calling the callback when
569	entering the the B<result> state, but will leave the request otherwise	699	entering the the B<result> state, but will leave the request otherwise
570	untouched. That means that requests that currently execute will not be	700	untouched. That means that requests that currently execute will not be
571	stopped and resources held by the request will not be freed prematurely.	701	stopped and resources held by the request will not be freed prematurely.
572		702
		703	=item cb $req $callback->(...)
		704
		705	Replace (or simply set) the callback registered to the request.
		706
573	=back	707	=back
574		708
575	=head2 IO::AIO::GRP CLASS	709	=head2 IO::AIO::GRP CLASS
576		710
577	This class is a subclass of L<IO::AIO::REQ>, so all its methods apply to	711	This class is a subclass of L<IO::AIO::REQ>, so all its methods apply to
…		…
616	=item * They can also can also be added to other IO::AIO::GRP objects.	750	=item * They can also can also be added to other IO::AIO::GRP objects.
617		751
618	=item * You must not add requests to a group from within the group callback (or	752	=item * You must not add requests to a group from within the group callback (or
619	any later time).	753	any later time).
620		754
621	=item * This does not harmonise well with C<max_outstanding>, so best do
622	not combine C<aio_group> with it. Groups and feeders are recommended for
623	this kind of concurrency-limiting.
624
625	=back	755	=back
626		756
627	Their lifetime, simplified, looks like this: when they are empty, they	757	Their lifetime, simplified, looks like this: when they are empty, they
628	will finish very quickly. If they contain only requests that are in the	758	will finish very quickly. If they contain only requests that are in the
629	C<done> state, they will also finish. Otherwise they will continue to	759	C<done> state, they will also finish. Otherwise they will continue to
…		…
634	group. And only when all those requests have finished will the the group	764	group. And only when all those requests have finished will the the group
635	itself finish.	765	itself finish.
636		766
637	=over 4	767	=over 4
638		768
		769	=item add $grp ...
		770
639	=item $grp->add (...)	771	=item $grp->add (...)
640
641	=item add $grp ...
642		772
643	Add one or more requests to the group. Any type of L<IO::AIO::REQ> can	773	Add one or more requests to the group. Any type of L<IO::AIO::REQ> can
644	be added, including other groups, as long as you do not create circular	774	be added, including other groups, as long as you do not create circular
645	dependencies.	775	dependencies.
646		776
647	Returns all its arguments.	777	Returns all its arguments.
648		778
		779	=item $grp->cancel_subs
		780
		781	Cancel all subrequests and clears any feeder, but not the group request
		782	itself. Useful when you queued a lot of events but got a result early.
		783
649	=item $grp->result (...)	784	=item $grp->result (...)
650		785
651	Set the result value(s) that will be passed to the group callback when all	786	Set the result value(s) that will be passed to the group callback when all
652	subrequests have finished. By default, no argument will be passed.	787	subrequests have finished and set thre groups errno to the current value
		788	of errno (just like calling C<errno> without an error number). By default,
		789	no argument will be passed and errno is zero.
653		790
654	=item $grp->set_feeder ($callback->($grp))	791	=item $grp->errno ([$errno])
655		792
656	[VERY EXPERIMENTAL]	793	Sets the group errno value to C<$errno>, or the current value of errno
		794	when the argument is missing.
		795
		796	Every aio request has an associated errno value that is restored when
		797	the callback is invoked. This method lets you change this value from its
		798	default (0).
		799
		800	Calling C<result> will also set errno, so make sure you either set C<$!>
		801	before the call to C<result>, or call c<errno> after it.
		802
		803	=item feed $grp $callback->($grp)
657		804
658	Sets a feeder/generator on this group: every group can have an attached	805	Sets a feeder/generator on this group: every group can have an attached
659	generator that generates requests if idle. The idea behind this is that,	806	generator that generates requests if idle. The idea behind this is that,
660	although you could just queue as many requests as you want in a group,	807	although you could just queue as many requests as you want in a group,
661	this might starve other requests for a potentially long time. For	808	this might starve other requests for a potentially long time. For
662	example, C<aio_scandir> might generate hundreds of thousands C<aio_stat>	809	example, C<aio_scandir> might generate hundreds of thousands C<aio_stat>
663	requests, delaying any later requests for a long time.	810	requests, delaying any later requests for a long time.
664		811
665	To avoid this, and allow incremental generation of requests, you can	812	To avoid this, and allow incremental generation of requests, you can
666	instead a group and set a feeder on it that generates those requests. The	813	instead a group and set a feeder on it that generates those requests. The
667	feeder will be called whenever there are few enough (see C<feeder_limit>,	814	feed callback will be called whenever there are few enough (see C<limit>,
668	below) requests active in the group itself and is expected to queue more	815	below) requests active in the group itself and is expected to queue more
669	requests.	816	requests.
670		817
671	The feeder can queue as many requests as it likes (i.e. C<add> does not	818	The feed callback can queue as many requests as it likes (i.e. C<add> does
672	impose any limits).	819	not impose any limits).
673		820
674	If the feeder does not queue more requests when called, it will be	821	If the feed does not queue more requests when called, it will be
675	automatically removed from the group.	822	automatically removed from the group.
676		823
677	If the feeder limit is C<0>, it will be set to C<2> automatically.	824	If the feed limit is C<0>, it will be set to C<2> automatically.
678		825
679	Example:	826	Example:
680		827
681	# stat all files in @files, but only ever use four aio requests concurrently:	828	# stat all files in @files, but only ever use four aio requests concurrently:
682		829
683	my $grp = aio_group sub { print "finished\n" };	830	my $grp = aio_group sub { print "finished\n" };
684	$grp->feeder_limit (4);	831	limit $grp 4;
685	$grp->set_feeder (sub {	832	feed $grp sub {
686	my $file = pop @files	833	my $file = pop @files
687	or return;	834	or return;
688		835
689	add $grp aio_stat $file, sub { ... };	836	add $grp aio_stat $file, sub { ... };
690	});	837	};
691		838
692	=item $grp->feeder_limit ($num)	839	=item limit $grp $num
693		840
694	Sets the feeder limit for the group: The feeder will be called whenever	841	Sets the feeder limit for the group: The feeder will be called whenever
695	the group contains less than this many requests.	842	the group contains less than this many requests.
696		843
697	Setting the limit to C<0> will pause the feeding process.	844	Setting the limit to C<0> will pause the feeding process.
…		…
715		862
716	Process all outstanding events on the result pipe. You have to call this	863	Process all outstanding events on the result pipe. You have to call this
717	regularly. Returns the number of events processed. Returns immediately	864	regularly. Returns the number of events processed. Returns immediately
718	when no events are outstanding.	865	when no events are outstanding.
719		866
		867	If not all requests were processed for whatever reason, the filehandle
		868	will still be ready when C<poll_cb> returns.
		869
720	Example: Install an Event watcher that automatically calls	870	Example: Install an Event watcher that automatically calls
721	IO::AIO::poll_cb with high priority:	871	IO::AIO::poll_cb with high priority:
722		872
723	Event->io (fd => IO::AIO::poll_fileno,	873	Event->io (fd => IO::AIO::poll_fileno,
724	poll => 'r', async => 1,	874	poll => 'r', async => 1,
725	cb => \&IO::AIO::poll_cb);	875	cb => \&IO::AIO::poll_cb);
726		876
		877	=item IO::AIO::poll_some $max_requests
		878
		879	Similar to C<poll_cb>, but only processes up to C<$max_requests> requests
		880	at a time.
		881
		882	Useful if you want to ensure some level of interactiveness when perl is
		883	not fast enough to process all requests in time.
		884
		885	Example: Install an Event watcher that automatically calls
		886	IO::AIO::poll_some with low priority, to ensure that other parts of the
		887	program get the CPU sometimes even under high AIO load.
		888
		889	Event->io (fd => IO::AIO::poll_fileno,
		890	poll => 'r', nice => 1,
		891	cb => sub { IO::AIO::poll_some 256 });
		892
727	=item IO::AIO::poll_wait	893	=item IO::AIO::poll_wait
728		894
729	Wait till the result filehandle becomes ready for reading (simply does a	895	Wait till the result filehandle becomes ready for reading (simply does a
730	C<select> on the filehandle. This is useful if you want to synchronously wait	896	C<select> on the filehandle. This is useful if you want to synchronously wait
731	for some requests to finish).	897	for some requests to finish).
732		898
733	See C<nreqs> for an example.	899	See C<nreqs> for an example.
734		900
735	=item IO::AIO::nreqs	901	=item IO::AIO::nreqs
736		902
737	Returns the number of requests currently outstanding (i.e. for which their	903	Returns the number of requests currently in the ready, execute or pending
738	callback has not been invoked yet).	904	states (i.e. for which their callback has not been invoked yet).
739		905
740	Example: wait till there are no outstanding requests anymore:	906	Example: wait till there are no outstanding requests anymore:
741		907
742	IO::AIO::poll_wait, IO::AIO::poll_cb	908	IO::AIO::poll_wait, IO::AIO::poll_cb
743	while IO::AIO::nreqs;	909	while IO::AIO::nreqs;
		910
		911	=item IO::AIO::nready
		912
		913	Returns the number of requests currently in the ready state (not yet
		914	executed).
		915
		916	=item IO::AIO::npending
		917
		918	Returns the number of requests currently in the pending state (executed,
		919	but not yet processed by poll_cb).
744		920
745	=item IO::AIO::flush	921	=item IO::AIO::flush
746		922
747	Wait till all outstanding AIO requests have been handled.	923	Wait till all outstanding AIO requests have been handled.
748		924
…		…
790	This module automatically runs C<max_parallel 0> at program end, to ensure	966	This module automatically runs C<max_parallel 0> at program end, to ensure
791	that all threads are killed and that there are no outstanding requests.	967	that all threads are killed and that there are no outstanding requests.
792		968
793	Under normal circumstances you don't need to call this function.	969	Under normal circumstances you don't need to call this function.
794		970
795	=item $oldnreqs = IO::AIO::max_outstanding $nreqs	971	=item $oldmaxreqs = IO::AIO::max_outstanding $maxreqs
796		972
797	[DEPRECATED]	973	This is a very bad function to use in interactive programs because it
		974	blocks, and a bad way to reduce concurrency because it is inexact: Better
		975	use an C<aio_group> together with a feed callback.
798		976
799	Sets the maximum number of outstanding requests to C<$nreqs>. If you	977	Sets the maximum number of outstanding requests to C<$nreqs>. If you
800	try to queue up more than this number of requests, the caller will block until	978	to queue up more than this number of requests, the next call to the
801	some requests have been handled.	979	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
		980	function will block until the limit is no longer exceeded.
802		981
803	The default is very large, so normally there is no practical limit. If you	982	The default value is very large, so there is no practical limit on the
804	queue up many requests in a loop it often improves speed if you set	983	number of outstanding requests.
805	this to a relatively low number, such as C<100>.
806		984
807	This function does not work well together with C<aio_group>'s, and their	985	You can still queue as many requests as you want. Therefore,
808	feeder interface is better suited to limiting concurrency, so do not use	986	C<max_oustsanding> is mainly useful in simple scripts (with low values) or
809	this function.	987	as a stop gap to shield against fatal memory overflow (with large values).
810
811	Under normal circumstances you don't need to call this function.
812		988
813	=back	989	=back
814		990
815	=cut	991	=cut
816		992
…		…
831	}	1007	}
832		1008
833	min_parallel 8;	1009	min_parallel 8;
834		1010
835	END {	1011	END {
836	max_parallel 0;	1012	min_parallel 1;
837	}	1013	flush;
		1014	};
838		1015
839	1;	1016	1;
840		1017
841	=head2 FORK BEHAVIOUR	1018	=head2 FORK BEHAVIOUR
842		1019
843	This module should do "the right thing" when the process using it forks:	1020	This module should do "the right thing" when the process using it forks:
844		1021
845	Before the fork, IO::AIO enters a quiescent state where no requests	1022	Before the fork, IO::AIO enters a quiescent state where no requests
846	can be added in other threads and no results will be processed. After	1023	can be added in other threads and no results will be processed. After
847	the fork the parent simply leaves the quiescent state and continues	1024	the fork the parent simply leaves the quiescent state and continues
848	request/result processing, while the child clears the request/result	1025	request/result processing, while the child frees the request/result queue
849	queue (so the requests started before the fork will only be handled in	1026	(so that the requests started before the fork will only be handled in the
850	the parent). Threads will be started on demand until the limit ste in the	1027	parent). Threads will be started on demand until the limit set in the
851	parent process has been reached again.	1028	parent process has been reached again.
852		1029
853	In short: the parent will, after a short pause, continue as if fork had	1030	In short: the parent will, after a short pause, continue as if fork had
854	not been called, while the child will act as if IO::AIO has not been used	1031	not been called, while the child will act as if IO::AIO has not been used
855	yet.	1032	yet.
856		1033
857	=head2 MEMORY USAGE	1034	=head2 MEMORY USAGE
858		1035
		1036	Per-request usage:
		1037
859	Each aio request uses - depending on your architecture - around 128 bytes	1038	Each aio request uses - depending on your architecture - around 100-200
860	of memory. In addition, stat requests need a stat buffer (possibly a few	1039	bytes of memory. In addition, stat requests need a stat buffer (possibly
861	hundred bytes). Perl scalars and other data passed into aio requests will	1040	a few hundred bytes), readdir requires a result buffer and so on. Perl
862	also be locked.	1041	scalars and other data passed into aio requests will also be locked and
		1042	will consume memory till the request has entered the done state.
863		1043
864	This is now awfully much, so queuing lots of requests is not usually a	1044	This is now awfully much, so queuing lots of requests is not usually a
865	problem.	1045	problem.
866		1046
867	Each thread needs a stack area which is usually around 16k, sometimes much	1047	Per-thread usage:
868	larger, depending on the OS.	1048
		1049	In the execution phase, some aio requests require more memory for
		1050	temporary buffers, and each thread requires a stack and other data
		1051	structures (usually around 16k-128k, depending on the OS).
		1052
		1053	=head1 KNOWN BUGS
		1054
		1055	Known bugs will be fixed in the next release.
869		1056
870	=head1 SEE ALSO	1057	=head1 SEE ALSO
871		1058
872	L<Coro>, L<Linux::AIO> (obsolete).	1059	L<Coro::AIO>.
873		1060
874	=head1 AUTHOR	1061	=head1 AUTHOR
875		1062
876	Marc Lehmann <schmorp@schmorp.de>	1063	Marc Lehmann <schmorp@schmorp.de>
877	http://home.schmorp.de/	1064	http://home.schmorp.de/

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Comparing IO-AIO/AIO.pm (file contents): Revision 1.62 by root, Sun Oct 22 21:13:47 2006 UTC vs. Revision 1.85 by root, Sat Oct 28 01:40:30 2006 UTC

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Comparing IO-AIO/AIO.pm (file contents):
Revision 1.62 by root, Sun Oct 22 21:13:47 2006 UTC vs.
Revision 1.85 by root, Sat Oct 28 01:40:30 2006 UTC