[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 1.85 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 perl, and	73	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	74	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	75	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	76	functions available on many operating systems. However, they are often
60	(Linux doesn't allow them on normal files currently, for example),	77	not well-supported or restricted (GNU/Linux doesn't allow them on normal
61	and they would only support aio_read and aio_write, so the remaining	78	files currently, for example), and they would only support aio_read and
62	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
…		…
79	our $VERSION = '2.0';	147	our $VERSION = '2.0';
80		148
81	our @AIO_REQ = 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 aio_nop);	152	aio_copy aio_group aio_nop aio_mknod);
85	our @EXPORT = (@AIO_REQ, qw(aioreq_pri));	153	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
86	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush	154	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
87	min_parallel max_parallel max_outstanding nreqs);	155	min_parallel max_parallel nreqs nready npending);
88		156
89	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';	157	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';
90		158
91	require XSLoader;	159	require XSLoader;
92	XSLoader::load ("IO::AIO", $VERSION);	160	XSLoader::load ("IO::AIO", $VERSION);
…		…
123	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)
124	use something else.	192	use something else.
125		193
126	=over 4	194	=over 4
127		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
128	=item aio_open $pathname, $flags, $mode, $callback->($fh)	227	=item aio_open $pathname, $flags, $mode, $callback->($fh)
129		228
130	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
131	created filehandle for the file.	230	created filehandle for the file.
132		231
…		…
181		280
182	aio_read $fh, 7, 15, $buffer, 0, sub {	281	aio_read $fh, 7, 15, $buffer, 0, sub {
183	$_[0] > 0 or die "read error: $!";	282	$_[0] > 0 or die "read error: $!";
184	print "read $_[0] bytes: <$buffer>\n";	283	print "read $_[0] bytes: <$buffer>\n";
185	};	284	};
186
187	=item aio_move $srcpath, $dstpath, $callback->($status)
188
189	[EXPERIMENTAL due to internal aio_group use]
190
191	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
193	the C<0> (error) or C<-1> ok.
194
195	This is a composite request that tries to rename(2) the file first. If
196	rename files with C<EXDEV>, it creates the destination file with mode 0200
197	and copies the contents of the source file into it using C<aio_sendfile>,
198	followed by restoring atime, mtime, access mode and uid/gid, in that
199	order, and unlinking the C<$srcpath>.
200
201	If an error occurs, the partial destination file will be unlinked, if
202	possible, except when setting atime, mtime, access mode and uid/gid, where
203	errors are being ignored.
204
205	=cut
206
207	sub aio_move($$$) {
208	my ($src, $dst, $cb) = @_;
209
210	my $grp = aio_group $cb;
211
212	add $grp aio_rename $src, $dst, sub {
213	if ($_[0] && $! == EXDEV) {
214	add $grp aio_open $src, O_RDONLY, 0, sub {
215	if (my $src_fh = $_[0]) {
216	my @stat = stat $src_fh;
217
218	add $grp aio_open $dst, O_WRONLY, 0200, sub {
219	if (my $dst_fh = $_[0]) {
220	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
221	close $src_fh;
222
223	if ($_[0] == $stat[7]) {
224	utime $stat[8], $stat[9], $dst;
225	chmod $stat[2] & 07777, $dst_fh;
226	chown $stat[4], $stat[5], $dst_fh;
227	close $dst_fh;
228
229	add $grp aio_unlink $src, sub {
230	$grp->result ($_[0]);
231	};
232	} else {
233	my $errno = $!;
234	add $grp aio_unlink $dst, sub {
235	$! = $errno;
236	$grp->result (-1);
237	};
238	}
239	};
240	} else {
241	$grp->result (-1);
242	}
243	},
244
245	} else {
246	$grp->result (-1);
247	}
248	};
249	} else {
250	$grp->result ($_[0]);
251	}
252	};
253
254	$grp
255	}
256		285
257	=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)
258		287
259	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
260	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
…		…
316	=item aio_unlink $pathname, $callback->($status)	345	=item aio_unlink $pathname, $callback->($status)
317		346
318	Asynchronously unlink (delete) a file and call the callback with the	347	Asynchronously unlink (delete) a file and call the callback with the
319	result code.	348	result code.
320		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
321	=item aio_link $srcpath, $dstpath, $callback->($status)	358	=item aio_link $srcpath, $dstpath, $callback->($status)
322		359
323	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
324	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.
325		362
…		…
345	sorted, and will B<NOT> include the C<.> and C<..> entries.	382	sorted, and will B<NOT> include the C<.> and C<..> entries.
346		383
347	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
348	with the filenames.	385	with the filenames.
349		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
350	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	489	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
351		490
352	[EXPERIMENTAL due to internal aio_group use]
353
354	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
355	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
356	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
357	recurse into (everything else).	494	recurse into (everything else, including symlinks to directories).
358		495
359	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_
360	C<$maxreq> specifies the maximum number of outstanding aio requests that	497	C<$maxreq> specifies the maximum number of outstanding aio requests that
361	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
362	will be chosen (currently 6).	499	will be chosen (currently 4).
363		500
364	On error, the callback is called without arguments, otherwise it receives	501	On error, the callback is called without arguments, otherwise it receives
365	two array-refs with path-relative entry names.	502	two array-refs with path-relative entry names.
366		503
367	Example:	504	Example:
…		…
404	=cut	541	=cut
405		542
406	sub aio_scandir($$$) {	543	sub aio_scandir($$$) {
407	my ($path, $maxreq, $cb) = @_;	544	my ($path, $maxreq, $cb) = @_;
408		545
		546	my $pri = aioreq_pri;
		547
409	my $grp = aio_group $cb;	548	my $grp = aio_group $cb;
410		549
411	$maxreq = 6 if $maxreq <= 0;	550	$maxreq = 4 if $maxreq <= 0;
412		551
413	# stat once	552	# stat once
		553	aioreq_pri $pri;
414	add $grp aio_stat $path, sub {	554	add $grp aio_stat $path, sub {
415	return $grp->result () if $_[0];	555	return $grp->result () if $_[0];
416	my $now = time;	556	my $now = time;
417	my $hash1 = join ":", (stat _)[0,1,3,7,9];	557	my $hash1 = join ":", (stat _)[0,1,3,7,9];
418		558
419	# read the directory entries	559	# read the directory entries
		560	aioreq_pri $pri;
420	add $grp aio_readdir $path, sub {	561	add $grp aio_readdir $path, sub {
421	my $entries = shift	562	my $entries = shift
422	or return $grp->result ();	563	or return $grp->result ();
423		564
424	# stat the dir another time	565	# stat the dir another time
		566	aioreq_pri $pri;
425	add $grp aio_stat $path, sub {	567	add $grp aio_stat $path, sub {
426	my $hash2 = join ":", (stat _)[0,1,3,7,9];	568	my $hash2 = join ":", (stat _)[0,1,3,7,9];
427		569
428	my $ndirs;	570	my $ndirs;
429		571
…		…
444	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],	586	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
445	@$entries];	587	@$entries];
446		588
447	my (@dirs, @nondirs);	589	my (@dirs, @nondirs);
448		590
449	my ($statcb, $schedcb);
450	my $nreq = 0;
451
452	my $statgrp = add $grp aio_group;	591	my $statgrp = add $grp aio_group sub {
		592	$grp->result (\@dirs, \@nondirs);
		593	};
453		594
454	$schedcb = sub {	595	limit $statgrp $maxreq;
455	if (@$entries) {	596	feed $statgrp sub {
456	if ($nreq < $maxreq) {	597	return unless @$entries;
457	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	}
458	$nreq++;	618	}
459	add $statgrp aio_stat "$path/$ent/.", sub { $statcb->($_[0], $ent) };
460	}	619	}
461	} elsif (!$nreq) {
462	# finished
463	$statgrp->cancel;
464	undef $statcb;
465	undef $schedcb;
466	$grp->result (\@dirs, \@nondirs);
467	}	620	};
468	};	621	};
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	};	622	};
499	};	623	};
500	};	624	};
501		625
502	$grp	626	$grp
…		…
515	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
516	detected, it will be emulated by calling C<fsync> instead.	640	detected, it will be emulated by calling C<fsync> instead.
517		641
518	=item aio_group $callback->(...)	642	=item aio_group $callback->(...)
519		643
520	[EXPERIMENTAL]
521
522	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
523	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
524	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.
525		648
526	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
527	for more info.	650	for more info.
528		651
529	Example:	652	Example:
…		…
548	phase and still requires a worker thread. Thus, the callback will not	671	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	672	be executed immediately but only after other requests in the queue have
550	entered their execution phase. This can be used to measure request	673	entered their execution phase. This can be used to measure request
551	latency.	674	latency.
552		675
553	=item IO::AIO::aio_sleep $fractional_seconds, $callback->() NOT EXPORTED	676	=item IO::AIO::aio_busy $fractional_seconds, $callback->() NOT EXPORTED
554		677
555	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
556	the request workers to sleep for the given time.	679	the request workers to sleep for the given time.
557		680
558	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
559	like sleep and file handle readable/writable, the overhead this creates	682	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	683	immense (it blocks a thread for a long time) so do not use this function
561	under artificial I/O pressure.	684	except to put your application under artificial I/O pressure.
562		685
563	=back	686	=back
564		687
565	=head2 IO::AIO::REQ CLASS	688	=head2 IO::AIO::REQ CLASS
566		689
567	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
568	called in non-void context.	691	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		692
578	=over 4	693	=over 4
579		694
580	=item cancel $req	695	=item cancel $req
581		696
…		…
635	=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.
636		751
637	=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
638	any later time).	753	any later time).
639		754
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	755	=back
645		756
646	Their lifetime, simplified, looks like this: when they are empty, they	757	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	758	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	759	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	774	be added, including other groups, as long as you do not create circular
664	dependencies.	775	dependencies.
665		776
666	Returns all its arguments.	777	Returns all its arguments.
667		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
668	=item $grp->result (...)	784	=item $grp->result (...)
669		785
670	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
671	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.
		790
		791	=item $grp->errno ([$errno])
		792
		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.
672		802
673	=item feed $grp $callback->($grp)	803	=item feed $grp $callback->($grp)
674
675	[VERY EXPERIMENTAL]
676		804
677	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
678	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,
679	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,
680	this might starve other requests for a potentially long time. For	808	this might starve other requests for a potentially long time. For
681	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>
682	requests, delaying any later requests for a long time.	810	requests, delaying any later requests for a long time.
683		811
684	To avoid this, and allow incremental generation of requests, you can	812	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	813	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>,	814	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	815	below) requests active in the group itself and is expected to queue more
688	requests.	816	requests.
689		817
690	The feed 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
691	impose any limits).	819	not impose any limits).
692		820
693	If the feed does not queue more requests when called, it will be	821	If the feed does not queue more requests when called, it will be
694	automatically removed from the group.	822	automatically removed from the group.
695		823
696	If the feed 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.
…		…
698	Example:	826	Example:
699		827
700	# 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:
701		829
702	my $grp = aio_group sub { print "finished\n" };	830	my $grp = aio_group sub { print "finished\n" };
703	feed_limit $grp 4;	831	limit $grp 4;
704	feed $grp sub {	832	feed $grp sub {
705	my $file = pop @files	833	my $file = pop @files
706	or return;	834	or return;
707		835
708	add $grp aio_stat $file, sub { ... };	836	add $grp aio_stat $file, sub { ... };
709	};	837	};
710		838
711	=item feed_limit $grp $num	839	=item limit $grp $num
712		840
713	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
714	the group contains less than this many requests.	842	the group contains less than this many requests.
715		843
716	Setting the limit to C<0> will pause the feeding process.	844	Setting the limit to C<0> will pause the feeding process.
…		…
734		862
735	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
736	regularly. Returns the number of events processed. Returns immediately	864	regularly. Returns the number of events processed. Returns immediately
737	when no events are outstanding.	865	when no events are outstanding.
738		866
		867	If not all requests were processed for whatever reason, the filehandle
		868	will still be ready when C<poll_cb> returns.
		869
739	Example: Install an Event watcher that automatically calls	870	Example: Install an Event watcher that automatically calls
740	IO::AIO::poll_cb with high priority:	871	IO::AIO::poll_cb with high priority:
741		872
742	Event->io (fd => IO::AIO::poll_fileno,	873	Event->io (fd => IO::AIO::poll_fileno,
743	poll => 'r', async => 1,	874	poll => 'r', async => 1,
744	cb => \&IO::AIO::poll_cb);	875	cb => \&IO::AIO::poll_cb);
745		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
746	=item IO::AIO::poll_wait	893	=item IO::AIO::poll_wait
747		894
748	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
749	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
750	for some requests to finish).	897	for some requests to finish).
751		898
752	See C<nreqs> for an example.	899	See C<nreqs> for an example.
753		900
754	=item IO::AIO::nreqs	901	=item IO::AIO::nreqs
755		902
756	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
757	callback has not been invoked yet).	904	states (i.e. for which their callback has not been invoked yet).
758		905
759	Example: wait till there are no outstanding requests anymore:	906	Example: wait till there are no outstanding requests anymore:
760		907
761	IO::AIO::poll_wait, IO::AIO::poll_cb	908	IO::AIO::poll_wait, IO::AIO::poll_cb
762	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).
763		920
764	=item IO::AIO::flush	921	=item IO::AIO::flush
765		922
766	Wait till all outstanding AIO requests have been handled.	923	Wait till all outstanding AIO requests have been handled.
767		924
…		…
809	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
810	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.
811		968
812	Under normal circumstances you don't need to call this function.	969	Under normal circumstances you don't need to call this function.
813		970
814	=item $oldnreqs = IO::AIO::max_outstanding $nreqs	971	=item $oldmaxreqs = IO::AIO::max_outstanding $maxreqs
815		972
816	[DEPRECATED]	973	This is a very bad function to use in interactive programs because it
		974	blocks, and a bad way to reduce concurrency because it is inexact: Better
		975	use an C<aio_group> together with a feed callback.
817		976
818	Sets the maximum number of outstanding requests to C<$nreqs>. If you	977	Sets the maximum number of outstanding requests to C<$nreqs>. If you
819	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
820	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.
821		981
822	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
823	queue up many requests in a loop it often improves speed if you set	983	number of outstanding requests.
824	this to a relatively low number, such as C<100>.
825		984
826	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,
827	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
828	this function.	987	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		988
832	=back	989	=back
833		990
834	=cut	991	=cut
835		992
…		…
850	}	1007	}
851		1008
852	min_parallel 8;	1009	min_parallel 8;
853		1010
854	END {	1011	END {
855	max_parallel 0;	1012	min_parallel 1;
856	}	1013	flush;
		1014	};
857		1015
858	1;	1016	1;
859		1017
860	=head2 FORK BEHAVIOUR	1018	=head2 FORK BEHAVIOUR
861		1019
862	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:
863		1021
864	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
865	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
866	the fork the parent simply leaves the quiescent state and continues	1024	the fork the parent simply leaves the quiescent state and continues
867	request/result processing, while the child clears the request/result	1025	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	1026	(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	1027	parent). Threads will be started on demand until the limit set in the
870	parent process has been reached again.	1028	parent process has been reached again.
871		1029
872	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
873	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
874	yet.	1032	yet.
875		1033
876	=head2 MEMORY USAGE	1034	=head2 MEMORY USAGE
877		1035
		1036	Per-request usage:
		1037
878	Each aio request uses - depending on your architecture - around 128 bytes	1038	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	1039	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	1040	a few hundred bytes), readdir requires a result buffer and so on. Perl
881	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.
882		1043
883	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
884	problem.	1045	problem.
885		1046
886	Each thread needs a stack area which is usually around 16k, sometimes much	1047	Per-thread usage:
887	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.
888		1056
889	=head1 SEE ALSO	1057	=head1 SEE ALSO
890		1058
891	L<Coro>, L<Linux::AIO> (obsolete).	1059	L<Coro::AIO>.
892		1060
893	=head1 AUTHOR	1061	=head1 AUTHOR
894		1062
895	Marc Lehmann <schmorp@schmorp.de>	1063	Marc Lehmann <schmorp@schmorp.de>
896	http://home.schmorp.de/	1064	http://home.schmorp.de/

Diff Legend

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

Comparing IO-AIO/AIO.pm (file contents): Revision 1.67 by root, Tue Oct 24 02:25:16 2006 UTC vs. Revision 1.85 by root, Sat Oct 28 01:40:30 2006 UTC

Diff Legend

Comparing IO-AIO/AIO.pm (file contents):
Revision 1.67 by root, Tue Oct 24 02:25:16 2006 UTC vs.
Revision 1.85 by root, Sat Oct 28 01:40:30 2006 UTC