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

Comparing IO-AIO/AIO.pm (file contents):
Revision 1.56 by root, Sun Oct 22 00:53:47 2006 UTC vs.
Revision 1.82 by root, Fri Oct 27 20:10:06 2006 UTC

…		…
18	};	18	};
19		19
20	# version 2+ has request and group objects	20	# version 2+ has request and group objects
21	use IO::AIO 2;	21	use IO::AIO 2;
22		22
		23	aioreq_pri 4; # give next request a very high priority
23	my $req = aio_unlink "/tmp/file", sub { };	24	my $req = aio_unlink "/tmp/file", sub { };
24	$req->cancel; # cancel request if still in queue	25	$req->cancel; # cancel request if still in queue
25		26
26	my $grp = aio_group sub { print "all stats done\n" };	27	my $grp = aio_group sub { print "all stats done\n" };
27	add $grp aio_stat "..." for ...;	28	add $grp aio_stat "..." for ...;
…		…
50	=head1 DESCRIPTION	51	=head1 DESCRIPTION
51		52
52	This module implements asynchronous I/O using whatever means your	53	This module implements asynchronous I/O using whatever means your
53	operating system supports.	54	operating system supports.
54		55
55	Currently, a number of threads are started that execute your read/writes	56	In this version, a number of threads are started that execute your
56	and signal their completion. You don't need thread support in your libc or	57	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	58	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	59	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	60	functions available on many operating systems. However, they are often
60	not well-supported (Linux doesn't allow them on normal files currently,	61	not well-supported or restricted (Linux doesn't allow them on normal
61	for example), and they would only support aio_read and aio_write, so the	62	files currently, for example), and they would only support aio_read and
62	remaining functionality would have to be implemented using threads anyway.	63	aio_write, so the remaining functionality would have to be implemented
		64	using threads anyway.
63		65
64	Although the module will work with in the presence of other threads, it is	66	Although the module will work with in the presence of other (Perl-)
65	currently not reentrant, so use appropriate locking yourself, always call	67	threads, it is currently not reentrant in any way, so use appropriate
66	C<poll_cb> from within the same thread, or never call C<poll_cb> (or other	68	locking yourself, always call C<poll_cb> from within the same thread, or
67	C<aio_> functions) recursively.	69	never call C<poll_cb> (or other C<aio_> functions) recursively.
		70
		71	=head1 REQUEST ANATOMY AND LIFETIME
		72
		73	Every C<aio_*> function creates a request. which is a C data structure not
		74	directly visible to Perl.
		75
		76	If called in non-void context, every request function returns a Perl
		77	object representing the request. In void context, nothing is returned,
		78	which saves a bit of memory.
		79
		80	The perl object is a fairly standard ref-to-hash object. The hash contents
		81	are not used by IO::AIO so you are free to store anything you like in it.
		82
		83	During their existance, aio requests travel through the following states,
		84	in order:
		85
		86	=over 4
		87
		88	=item ready
		89
		90	Immediately after a request is created it is put into the ready state,
		91	waiting for a thread to execute it.
		92
		93	=item execute
		94
		95	A thread has accepted the request for processing and is currently
		96	executing it (e.g. blocking in read).
		97
		98	=item pending
		99
		100	The request has been executed and is waiting for result processing.
		101
		102	While request submission and execution is fully asynchronous, result
		103	processing is not and relies on the perl interpreter calling C<poll_cb>
		104	(or another function with the same effect).
		105
		106	=item result
		107
		108	The request results are processed synchronously by C<poll_cb>.
		109
		110	The C<poll_cb> function will process all outstanding aio requests by
		111	calling their callbacks, freeing memory associated with them and managing
		112	any groups they are contained in.
		113
		114	=item done
		115
		116	Request has reached the end of its lifetime and holds no resources anymore
		117	(except possibly for the Perl object, but its connection to the actual
		118	aio request is severed and calling its methods will either do nothing or
		119	result in a runtime error).
68		120
69	=cut	121	=cut
70		122
71	package IO::AIO;	123	package IO::AIO;
72		124
…		…
76	use base 'Exporter';	128	use base 'Exporter';
77		129
78	BEGIN {	130	BEGIN {
79	our $VERSION = '2.0';	131	our $VERSION = '2.0';
80		132
81	our @EXPORT = qw(aio_sendfile aio_read aio_write aio_open aio_close aio_stat	133	our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close aio_stat
82	aio_lstat aio_unlink aio_rmdir aio_readdir aio_scandir aio_symlink	134	aio_lstat aio_unlink aio_rmdir aio_readdir aio_scandir aio_symlink
83	aio_fsync aio_fdatasync aio_readahead aio_rename aio_link aio_move	135	aio_fsync aio_fdatasync aio_readahead aio_rename aio_link aio_move
84	aio_group);	136	aio_copy aio_group aio_nop aio_mknod);
85	our @EXPORT_OK = qw(poll_fileno poll_cb min_parallel max_parallel max_outstanding nreqs);	137	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
		138	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
		139	min_parallel max_parallel nreqs nready npending);
86		140
87	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';	141	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';
88		142
89	require XSLoader;	143	require XSLoader;
90	XSLoader::load ("IO::AIO", $VERSION);	144	XSLoader::load ("IO::AIO", $VERSION);
…		…
121	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)
122	use something else.	176	use something else.
123		177
124	=over 4	178	=over 4
125		179
		180	=item $prev_pri = aioreq_pri [$pri]
		181
		182	Returns the priority value that would be used for the next request and, if
		183	C<$pri> is given, sets the priority for the next aio request.
		184
		185	The default priority is C<0>, the minimum and maximum priorities are C<-4>
		186	and C<4>, respectively. Requests with higher priority will be serviced
		187	first.
		188
		189	The priority will be reset to C<0> after each call to one of the C<aio_*>
		190	functions.
		191
		192	Example: open a file with low priority, then read something from it with
		193	higher priority so the read request is serviced before other low priority
		194	open requests (potentially spamming the cache):
		195
		196	aioreq_pri -3;
		197	aio_open ..., sub {
		198	return unless $_[0];
		199
		200	aioreq_pri -2;
		201	aio_read $_[0], ..., sub {
		202	...
		203	};
		204	};
		205
		206	=item aioreq_nice $pri_adjust
		207
		208	Similar to C<aioreq_pri>, but subtracts the given value from the current
		209	priority, so effects are cumulative.
		210
126	=item aio_open $pathname, $flags, $mode, $callback->($fh)	211	=item aio_open $pathname, $flags, $mode, $callback->($fh)
127		212
128	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
129	created filehandle for the file.	214	created filehandle for the file.
130		215
…		…
179		264
180	aio_read $fh, 7, 15, $buffer, 0, sub {	265	aio_read $fh, 7, 15, $buffer, 0, sub {
181	$_[0] > 0 or die "read error: $!";	266	$_[0] > 0 or die "read error: $!";
182	print "read $_[0] bytes: <$buffer>\n";	267	print "read $_[0] bytes: <$buffer>\n";
183	};	268	};
184
185	=item aio_move $srcpath, $dstpath, $callback->($status)
186
187	Try to move the I<file> (directories not supported as either source or
188	destination) from C<$srcpath> to C<$dstpath> and call the callback with
189	the C<0> (error) or C<-1> ok.
190
191	This is a composite request that tries to rename(2) the file first. If
192	rename files with C<EXDEV>, it creates the destination file with mode 0200
193	and copies the contents of the source file into it using C<aio_sendfile>,
194	followed by restoring atime, mtime, access mode and uid/gid, in that
195	order, and unlinking the C<$srcpath>.
196
197	If an error occurs, the partial destination file will be unlinked, if
198	possible, except when setting atime, mtime, access mode and uid/gid, where
199	errors are being ignored.
200
201	=cut
202
203	sub aio_move($$$) {
204	my ($src, $dst, $cb) = @_;
205
206	my $grp = aio_group;
207
208	add $grp aio_rename $src, $dst, sub {
209	if ($_[0] && $! == EXDEV) {
210	add $grp aio_open $src, O_RDONLY, 0, sub {
211	if (my $src_fh = $_[0]) {
212	my @stat = stat $src_fh;
213
214	add $grp aio_open $dst, O_WRONLY, 0200, sub {
215	if (my $dst_fh = $_[0]) {
216	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
217	close $src_fh;
218
219	if ($_[0] == $stat[7]) {
220	utime $stat[8], $stat[9], $dst;
221	chmod $stat[2] & 07777, $dst_fh;
222	chown $stat[4], $stat[5], $dst_fh;
223	close $dst_fh;
224
225	add $grp aio_unlink $src, sub {
226	$cb->($_[0]);
227	};
228	} else {
229	my $errno = $!;
230	add $grp aio_unlink $dst, sub {
231	$! = $errno;
232	$cb->(-1);
233	};
234	}
235	};
236	} else {
237	$cb->(-1);
238	}
239	},
240
241	} else {
242	$cb->(-1);
243	}
244	};
245	} else {
246	$cb->($_[0]);
247	}
248	};
249
250	$grp
251	}
252		269
253	=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)
254		271
255	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
256	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
…		…
312	=item aio_unlink $pathname, $callback->($status)	329	=item aio_unlink $pathname, $callback->($status)
313		330
314	Asynchronously unlink (delete) a file and call the callback with the	331	Asynchronously unlink (delete) a file and call the callback with the
315	result code.	332	result code.
316		333
		334	=item aio_mknod $path, $mode, $dev, $callback->($status)
		335
		336	Asynchronously create a device node (or fifo). See mknod(2): the only
		337	portable value for C<$mode> is C<S_IFIFO> ored with permissions, and C<0>
		338	for C<$dev>.
		339
317	=item aio_link $srcpath, $dstpath, $callback->($status)	340	=item aio_link $srcpath, $dstpath, $callback->($status)
318		341
319	Asynchronously create a new link to the existing object at C<$srcpath> at	342	Asynchronously create a new link to the existing object at C<$srcpath> at
320	the path C<$dstpath> and call the callback with the result code.	343	the path C<$dstpath> and call the callback with the result code.
321		344
…		…
341	sorted, and will B<NOT> include the C<.> and C<..> entries.	364	sorted, and will B<NOT> include the C<.> and C<..> entries.
342		365
343	The callback a single argument which is either C<undef> or an array-ref	366	The callback a single argument which is either C<undef> or an array-ref
344	with the filenames.	367	with the filenames.
345		368
		369	=item aio_copy $srcpath, $dstpath, $callback->($status)
		370
		371	Try to copy the I<file> (directories not supported as either source or
		372	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		373	the C<0> (error) or C<-1> ok.
		374
		375	This is a composite request that it creates the destination file with
		376	mode 0200 and copies the contents of the source file into it using
		377	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
		378	uid/gid, in that order.
		379
		380	If an error occurs, the partial destination file will be unlinked, if
		381	possible, except when setting atime, mtime, access mode and uid/gid, where
		382	errors are being ignored.
		383
		384	=cut
		385
		386	sub aio_copy($$;$) {
		387	my ($src, $dst, $cb) = @_;
		388
		389	my $pri = aioreq_pri;
		390	my $grp = aio_group $cb;
		391
		392	aioreq_pri $pri;
		393	add $grp aio_open $src, O_RDONLY, 0, sub {
		394	if (my $src_fh = $_[0]) {
		395	my @stat = stat $src_fh;
		396
		397	aioreq_pri $pri;
		398	add $grp aio_open $dst, O_CREAT \| O_WRONLY \| O_TRUNC, 0200, sub {
		399	if (my $dst_fh = $_[0]) {
		400	aioreq_pri $pri;
		401	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
		402	if ($_[0] == $stat[7]) {
		403	$grp->result (0);
		404	close $src_fh;
		405
		406	# those should not normally block. should. should.
		407	utime $stat[8], $stat[9], $dst;
		408	chmod $stat[2] & 07777, $dst_fh;
		409	chown $stat[4], $stat[5], $dst_fh;
		410	close $dst_fh;
		411	} else {
		412	$grp->result (-1);
		413	close $src_fh;
		414	close $dst_fh;
		415
		416	aioreq $pri;
		417	add $grp aio_unlink $dst;
		418	}
		419	};
		420	} else {
		421	$grp->result (-1);
		422	}
		423	},
		424
		425	} else {
		426	$grp->result (-1);
		427	}
		428	};
		429
		430	$grp
		431	}
		432
		433	=item aio_move $srcpath, $dstpath, $callback->($status)
		434
		435	Try to move the I<file> (directories not supported as either source or
		436	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		437	the C<0> (error) or C<-1> ok.
		438
		439	This is a composite request that tries to rename(2) the file first. If
		440	rename files with C<EXDEV>, it copies the file with C<aio_copy> and, if
		441	that is successful, unlinking the C<$srcpath>.
		442
		443	=cut
		444
		445	sub aio_move($$;$) {
		446	my ($src, $dst, $cb) = @_;
		447
		448	my $pri = aioreq_pri;
		449	my $grp = aio_group $cb;
		450
		451	aioreq_pri $pri;
		452	add $grp aio_rename $src, $dst, sub {
		453	if ($_[0] && $! == EXDEV) {
		454	aioreq_pri $pri;
		455	add $grp aio_copy $src, $dst, sub {
		456	$grp->result ($_[0]);
		457
		458	if (!$_[0]) {
		459	aioreq_pri $pri;
		460	add $grp aio_unlink $src;
		461	}
		462	};
		463	} else {
		464	$grp->result ($_[0]);
		465	}
		466	};
		467
		468	$grp
		469	}
		470
346	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	471	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
347		472
348	Scans a directory (similar to C<aio_readdir>) but additionally tries to	473	Scans a directory (similar to C<aio_readdir>) but additionally tries to
349	separate the entries of directory C<$path> into two sets of names, ones	474	efficiently separate the entries of directory C<$path> into two sets of
350	you can recurse into (directories or links to them), and ones you cannot	475	names, directories you can recurse into (directories), and ones you cannot
351	recurse into (everything else).	476	recurse into (everything else, including symlinks to directories).
352		477
353	C<aio_scandir> is a composite request that consists of many sub	478	C<aio_scandir> is a composite request that creates of many sub requests_
354	requests. C<$maxreq> specifies the maximum number of outstanding aio	479	C<$maxreq> specifies the maximum number of outstanding aio requests that
355	requests that this function generates. If it is C<< <= 0 >>, then a	480	this function generates. If it is C<< <= 0 >>, then a suitable default
356	suitable default will be chosen (currently 8).	481	will be chosen (currently 4).
357		482
358	On error, the callback is called without arguments, otherwise it receives	483	On error, the callback is called without arguments, otherwise it receives
359	two array-refs with path-relative entry names.	484	two array-refs with path-relative entry names.
360		485
361	Example:	486	Example:
…		…
398	=cut	523	=cut
399		524
400	sub aio_scandir($$$) {	525	sub aio_scandir($$$) {
401	my ($path, $maxreq, $cb) = @_;	526	my ($path, $maxreq, $cb) = @_;
402		527
		528	my $pri = aioreq_pri;
		529
403	my $grp = aio_group;	530	my $grp = aio_group $cb;
404		531
405	$maxreq = 8 if $maxreq <= 0;	532	$maxreq = 4 if $maxreq <= 0;
406		533
407	# stat once	534	# stat once
		535	aioreq_pri $pri;
408	add $grp aio_stat $path, sub {	536	add $grp aio_stat $path, sub {
409	return $cb->() if $_[0];	537	return $grp->result () if $_[0];
410	my $now = time;	538	my $now = time;
411	my $hash1 = join ":", (stat _)[0,1,3,7,9];	539	my $hash1 = join ":", (stat _)[0,1,3,7,9];
412		540
413	# read the directory entries	541	# read the directory entries
		542	aioreq_pri $pri;
414	add $grp aio_readdir $path, sub {	543	add $grp aio_readdir $path, sub {
415	my $entries = shift	544	my $entries = shift
416	or return $cb->();	545	or return $grp->result ();
417		546
418	# stat the dir another time	547	# stat the dir another time
		548	aioreq_pri $pri;
419	add $grp aio_stat $path, sub {	549	add $grp aio_stat $path, sub {
420	my $hash2 = join ":", (stat _)[0,1,3,7,9];	550	my $hash2 = join ":", (stat _)[0,1,3,7,9];
421		551
422	my $ndirs;	552	my $ndirs;
423		553
…		…
426	$ndirs = -1;	556	$ndirs = -1;
427	} else {	557	} else {
428	# if nlink == 2, we are finished	558	# if nlink == 2, we are finished
429	# on non-posix-fs's, we rely on nlink < 2	559	# on non-posix-fs's, we rely on nlink < 2
430	$ndirs = (stat _)[3] - 2	560	$ndirs = (stat _)[3] - 2
431	or return $cb->([], $entries);	561	or return $grp->result ([], $entries);
432	}	562	}
433		563
434	# sort into likely dirs and likely nondirs	564	# sort into likely dirs and likely nondirs
435	# dirs == files without ".", short entries first	565	# dirs == files without ".", short entries first
436	$entries = [map $_->[0],	566	$entries = [map $_->[0],
…		…
438	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],	568	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
439	@$entries];	569	@$entries];
440		570
441	my (@dirs, @nondirs);	571	my (@dirs, @nondirs);
442		572
443	my ($statcb, $schedcb);	573	my $statgrp = add $grp aio_group sub {
444	my $nreq = 0;	574	$grp->result (\@dirs, \@nondirs);
		575	};
445		576
446	$schedcb = sub {	577	limit $statgrp $maxreq;
447	if (@$entries) {	578	feed $statgrp sub {
448	if ($nreq < $maxreq) {	579	return unless @$entries;
449	my $ent = pop @$entries;	580	my $entry = pop @$entries;
		581
		582	aioreq_pri $pri;
		583	add $statgrp aio_stat "$path/$entry/.", sub {
		584	if ($_[0] < 0) {
		585	push @nondirs, $entry;
		586	} else {
		587	# need to check for real directory
		588	aioreq_pri $pri;
		589	add $statgrp aio_lstat "$path/$entry", sub {
		590	if (-d _) {
		591	push @dirs, $entry;
		592
		593	unless (--$ndirs) {
		594	push @nondirs, @$entries;
		595	feed $statgrp;
		596	}
		597	} else {
		598	push @nondirs, $entry;
		599	}
450	$nreq++;	600	}
451	add $grp aio_stat "$path/$ent/.", sub { $statcb->($_[0], $ent) };
452	}	601	}
453	} elsif (!$nreq) {
454	# finished
455	undef $statcb;
456	undef $schedcb;
457	$cb->(\@dirs, \@nondirs) if $cb;
458	undef $cb;
459	}	602	};
460	};	603	};
461	$statcb = sub {
462	my ($status, $entry) = @_;
463
464	if ($status < 0) {
465	$nreq--;
466	push @nondirs, $entry;
467	&$schedcb;
468	} else {
469	# need to check for real directory
470	add $grp aio_lstat "$path/$entry", sub {
471	$nreq--;
472
473	if (-d _) {
474	push @dirs, $entry;
475
476	if (!--$ndirs) {
477	push @nondirs, @$entries;
478	$entries = [];
479	}
480	} else {
481	push @nondirs, $entry;
482	}
483
484	&$schedcb;
485	}
486	}
487	};
488
489	&$schedcb while @$entries && $nreq < $maxreq;
490	};	604	};
491	};	605	};
492	};	606	};
493		607
494	$grp	608	$grp
…		…
505	callback with the fdatasync result code.	619	callback with the fdatasync result code.
506		620
507	If this call isn't available because your OS lacks it or it couldn't be	621	If this call isn't available because your OS lacks it or it couldn't be
508	detected, it will be emulated by calling C<fsync> instead.	622	detected, it will be emulated by calling C<fsync> instead.
509		623
510	=item aio_group $callback->()	624	=item aio_group $callback->(...)
511
512	[EXPERIMENTAL]
513		625
514	This is a very special aio request: Instead of doing something, it is a	626	This is a very special aio request: Instead of doing something, it is a
515	container for other aio requests, which is useful if you want to bundle	627	container for other aio requests, which is useful if you want to bundle
516	many requests into a single, composite, request.	628	many requests into a single, composite, request with a definite callback
		629	and the ability to cancel the whole request with its subrequests.
517		630
518	Returns an object of class L<IO::AIO::GRP>. See its documentation below	631	Returns an object of class L<IO::AIO::GRP>. See its documentation below
519	for more info.	632	for more info.
520		633
521	Example:	634	Example:
…		…
527	add $grp	640	add $grp
528	(aio_stat ...),	641	(aio_stat ...),
529	(aio_stat ...),	642	(aio_stat ...),
530	...;	643	...;
531		644
		645	=item aio_nop $callback->()
		646
		647	This is a special request - it does nothing in itself and is only used for
		648	side effects, such as when you want to add a dummy request to a group so
		649	that finishing the requests in the group depends on executing the given
		650	code.
		651
		652	While this request does nothing, it still goes through the execution
		653	phase and still requires a worker thread. Thus, the callback will not
		654	be executed immediately but only after other requests in the queue have
		655	entered their execution phase. This can be used to measure request
		656	latency.
		657
532	=item IO::AIO::aio_sleep $fractional_seconds, $callback->() NOT EXPORTED	658	=item IO::AIO::aio_busy $fractional_seconds, $callback->() NOT EXPORTED
533		659
534	Mainly used for debugging and benchmarking, this aio request puts one of	660	Mainly used for debugging and benchmarking, this aio request puts one of
535	the request workers to sleep for the given time.	661	the request workers to sleep for the given time.
536		662
537	While it is theoretically handy to have simple I/O scheduling requests	663	While it is theoretically handy to have simple I/O scheduling requests
538	like sleep and file handle readable/writable, the overhead this creates	664	like sleep and file handle readable/writable, the overhead this creates is
539	is immense, so do not use this function except to put your application	665	immense (it blocks a thread for a long time) so do not use this function
540	under artificial I/O pressure.	666	except to put your application under artificial I/O pressure.
541		667
542	=back	668	=back
543		669
544	=head2 IO::AIO::REQ CLASS	670	=head2 IO::AIO::REQ CLASS
545		671
546	All non-aggregate C<aio_*> functions return an object of this class when	672	All non-aggregate C<aio_*> functions return an object of this class when
547	called in non-void context.	673	called in non-void context.
548		674
549	A request always moves through the following five states in its lifetime,
550	in order: B<ready> (request has been created, but has not been executed
551	yet), B<execute> (request is currently being executed), B<pending>
552	(request has been executed but callback has not been called yet),
553	B<result> (results are being processed synchronously, includes calling the
554	callback) and B<done> (request has reached the end of its lifetime and
555	holds no resources anymore).
556
557	=over 4	675	=over 4
558		676
559	=item $req->cancel	677	=item cancel $req
560		678
561	Cancels the request, if possible. Has the effect of skipping execution	679	Cancels the request, if possible. Has the effect of skipping execution
562	when entering the B<execute> state and skipping calling the callback when	680	when entering the B<execute> state and skipping calling the callback when
563	entering the the B<result> state, but will leave the request otherwise	681	entering the the B<result> state, but will leave the request otherwise
564	untouched. That means that requests that currently execute will not be	682	untouched. That means that requests that currently execute will not be
565	stopped and resources held by the request will not be freed prematurely.	683	stopped and resources held by the request will not be freed prematurely.
566		684
		685	=item cb $req $callback->(...)
		686
		687	Replace (or simply set) the callback registered to the request.
		688
567	=back	689	=back
568		690
569	=head2 IO::AIO::GRP CLASS	691	=head2 IO::AIO::GRP CLASS
570		692
571	This class is a subclass of L<IO::AIO::REQ>, so all its methods apply to	693	This class is a subclass of L<IO::AIO::REQ>, so all its methods apply to
…		…
585	You add requests by calling the C<add> method with one or more	707	You add requests by calling the C<add> method with one or more
586	C<IO::AIO::REQ> objects:	708	C<IO::AIO::REQ> objects:
587		709
588	$grp->add (aio_unlink "...");	710	$grp->add (aio_unlink "...");
589		711
590	add $grp aio_stat "...", sub { ... };	712	add $grp aio_stat "...", sub {
		713	$_[0] or return $grp->result ("error");
		714
		715	# add another request dynamically, if first succeeded
		716	add $grp aio_open "...", sub {
		717	$grp->result ("ok");
		718	};
		719	};
591		720
592	This makes it very easy to create composite requests (see the source of	721	This makes it very easy to create composite requests (see the source of
593	C<aio_move> for an application) that work and feel like simple requests.	722	C<aio_move> for an application) that work and feel like simple requests.
594		723
		724	=over 4
		725
595	The IO::AIO::GRP objects will be cleaned up during calls to	726	=item * The IO::AIO::GRP objects will be cleaned up during calls to
596	C<IO::AIO::poll_cb>, just like any other request.	727	C<IO::AIO::poll_cb>, just like any other request.
597		728
598	They can be canceled like any other request. Canceling will cancel not	729	=item * They can be canceled like any other request. Canceling will cancel not
599	just the request itself, but also all requests it contains.	730	only the request itself, but also all requests it contains.
600		731
601	They can also can also be added to other IO::AIO::GRP objects.	732	=item * They can also can also be added to other IO::AIO::GRP objects.
		733
		734	=item * You must not add requests to a group from within the group callback (or
		735	any later time).
		736
		737	=back
602		738
603	Their lifetime, simplified, looks like this: when they are empty, they	739	Their lifetime, simplified, looks like this: when they are empty, they
604	will finish very quickly. If they contain only requests that are in the	740	will finish very quickly. If they contain only requests that are in the
605	C<done> state, they will also finish. Otherwise they will continue to	741	C<done> state, they will also finish. Otherwise they will continue to
606	exist.	742	exist.
607		743
		744	That means after creating a group you have some time to add requests. And
		745	in the callbacks of those requests, you can add further requests to the
		746	group. And only when all those requests have finished will the the group
		747	itself finish.
		748
608	=over 4	749	=over 4
609		750
		751	=item add $grp ...
		752
610	=item $grp->add (...)	753	=item $grp->add (...)
611		754
612	=item add $grp ...	755	Add one or more requests to the group. Any type of L<IO::AIO::REQ> can
		756	be added, including other groups, as long as you do not create circular
		757	dependencies.
613		758
614	Add one or more	759	Returns all its arguments.
615	Cancels the request, if possible. Has the effect of skipping execution	760
616	when entering the B<execute> state and skipping calling the callback when	761	=item $grp->cancel_subs
617	entering the the B<result> state, but will leave the request otherwise	762
618	untouched. That means that requests that currently execute will not be	763	Cancel all subrequests and clears any feeder, but not the group request
619	stopped and resources held by the request will not be freed prematurely.	764	itself. Useful when you queued a lot of events but got a result early.
		765
		766	=item $grp->result (...)
		767
		768	Set the result value(s) that will be passed to the group callback when all
		769	subrequests have finished and set thre groups errno to the current value
		770	of errno (just like calling C<errno> without an error number). By default,
		771	no argument will be passed and errno is zero.
		772
		773	=item $grp->errno ([$errno])
		774
		775	Sets the group errno value to C<$errno>, or the current value of errno
		776	when the argument is missing.
		777
		778	Every aio request has an associated errno value that is restored when
		779	the callback is invoked. This method lets you change this value from its
		780	default (0).
		781
		782	Calling C<result> will also set errno, so make sure you either set C<$!>
		783	before the call to C<result>, or call c<errno> after it.
		784
		785	=item feed $grp $callback->($grp)
		786
		787	Sets a feeder/generator on this group: every group can have an attached
		788	generator that generates requests if idle. The idea behind this is that,
		789	although you could just queue as many requests as you want in a group,
		790	this might starve other requests for a potentially long time. For
		791	example, C<aio_scandir> might generate hundreds of thousands C<aio_stat>
		792	requests, delaying any later requests for a long time.
		793
		794	To avoid this, and allow incremental generation of requests, you can
		795	instead a group and set a feeder on it that generates those requests. The
		796	feed callback will be called whenever there are few enough (see C<limit>,
		797	below) requests active in the group itself and is expected to queue more
		798	requests.
		799
		800	The feed callback can queue as many requests as it likes (i.e. C<add> does
		801	not impose any limits).
		802
		803	If the feed does not queue more requests when called, it will be
		804	automatically removed from the group.
		805
		806	If the feed limit is C<0>, it will be set to C<2> automatically.
		807
		808	Example:
		809
		810	# stat all files in @files, but only ever use four aio requests concurrently:
		811
		812	my $grp = aio_group sub { print "finished\n" };
		813	limit $grp 4;
		814	feed $grp sub {
		815	my $file = pop @files
		816	or return;
		817
		818	add $grp aio_stat $file, sub { ... };
		819	};
		820
		821	=item limit $grp $num
		822
		823	Sets the feeder limit for the group: The feeder will be called whenever
		824	the group contains less than this many requests.
		825
		826	Setting the limit to C<0> will pause the feeding process.
620		827
621	=back	828	=back
622		829
623	=head2 SUPPORT FUNCTIONS	830	=head2 SUPPORT FUNCTIONS
624		831
…		…
637		844
638	Process all outstanding events on the result pipe. You have to call this	845	Process all outstanding events on the result pipe. You have to call this
639	regularly. Returns the number of events processed. Returns immediately	846	regularly. Returns the number of events processed. Returns immediately
640	when no events are outstanding.	847	when no events are outstanding.
641		848
		849	If not all requests were processed for whatever reason, the filehandle
		850	will still be ready when C<poll_cb> returns.
		851
642	Example: Install an Event watcher that automatically calls	852	Example: Install an Event watcher that automatically calls
643	IO::AIO::poll_cb with high priority:	853	IO::AIO::poll_cb with high priority:
644		854
645	Event->io (fd => IO::AIO::poll_fileno,	855	Event->io (fd => IO::AIO::poll_fileno,
646	poll => 'r', async => 1,	856	poll => 'r', async => 1,
647	cb => \&IO::AIO::poll_cb);	857	cb => \&IO::AIO::poll_cb);
648		858
		859	=item IO::AIO::poll_some $max_requests
		860
		861	Similar to C<poll_cb>, but only processes up to C<$max_requests> requests
		862	at a time.
		863
		864	Useful if you want to ensure some level of interactiveness when perl is
		865	not fast enough to process all requests in time.
		866
		867	Example: Install an Event watcher that automatically calls
		868	IO::AIO::poll_some with low priority, to ensure that other parts of the
		869	program get the CPU sometimes even under high AIO load.
		870
		871	Event->io (fd => IO::AIO::poll_fileno,
		872	poll => 'r', nice => 1,
		873	cb => sub { IO::AIO::poll_some 256 });
		874
649	=item IO::AIO::poll_wait	875	=item IO::AIO::poll_wait
650		876
651	Wait till the result filehandle becomes ready for reading (simply does a	877	Wait till the result filehandle becomes ready for reading (simply does a
652	C<select> on the filehandle. This is useful if you want to synchronously wait	878	C<select> on the filehandle. This is useful if you want to synchronously wait
653	for some requests to finish).	879	for some requests to finish).
654		880
655	See C<nreqs> for an example.	881	See C<nreqs> for an example.
656		882
657	=item IO::AIO::nreqs	883	=item IO::AIO::nreqs
658		884
659	Returns the number of requests currently outstanding (i.e. for which their	885	Returns the number of requests currently in the ready, execute or pending
660	callback has not been invoked yet).	886	states (i.e. for which their callback has not been invoked yet).
661		887
662	Example: wait till there are no outstanding requests anymore:	888	Example: wait till there are no outstanding requests anymore:
663		889
664	IO::AIO::poll_wait, IO::AIO::poll_cb	890	IO::AIO::poll_wait, IO::AIO::poll_cb
665	while IO::AIO::nreqs;	891	while IO::AIO::nreqs;
666		892
		893	=item IO::AIO::nready
		894
		895	Returns the number of requests currently in the ready state (not yet
		896	executed).
		897
		898	=item IO::AIO::npending
		899
		900	Returns the number of requests currently in the pending state (executed,
		901	but not yet processed by poll_cb).
		902
667	=item IO::AIO::flush	903	=item IO::AIO::flush
668		904
669	Wait till all outstanding AIO requests have been handled.	905	Wait till all outstanding AIO requests have been handled.
670		906
671	Strictly equivalent to:	907	Strictly equivalent to:
…		…
682	IO::AIO::poll_wait, IO::AIO::poll_cb	918	IO::AIO::poll_wait, IO::AIO::poll_cb
683	if IO::AIO::nreqs;	919	if IO::AIO::nreqs;
684		920
685	=item IO::AIO::min_parallel $nthreads	921	=item IO::AIO::min_parallel $nthreads
686		922
687	Set the minimum number of AIO threads to C<$nthreads>. The current default	923	Set the minimum number of AIO threads to C<$nthreads>. The current
688	is C<4>, which means four asynchronous operations can be done at one time	924	default is C<8>, which means eight asynchronous operations can execute
689	(the number of outstanding operations, however, is unlimited).	925	concurrently at any one time (the number of outstanding requests,
		926	however, is unlimited).
690		927
691	IO::AIO starts threads only on demand, when an AIO request is queued and	928	IO::AIO starts threads only on demand, when an AIO request is queued and
692	no free thread exists.	929	no free thread exists.
693		930
694	It is recommended to keep the number of threads low, as some Linux	931	It is recommended to keep the number of threads relatively low, as some
695	kernel versions will scale negatively with the number of threads (higher	932	Linux kernel versions will scale negatively with the number of threads
696	parallelity => MUCH higher latency). With current Linux 2.6 versions, 4-32	933	(higher parallelity => MUCH higher latency). With current Linux 2.6
697	threads should be fine.	934	versions, 4-32 threads should be fine.
698		935
699	Under most circumstances you don't need to call this function, as the	936	Under most circumstances you don't need to call this function, as the
700	module selects a default that is suitable for low to moderate load.	937	module selects a default that is suitable for low to moderate load.
701		938
702	=item IO::AIO::max_parallel $nthreads	939	=item IO::AIO::max_parallel $nthreads
…		…
711	This module automatically runs C<max_parallel 0> at program end, to ensure	948	This module automatically runs C<max_parallel 0> at program end, to ensure
712	that all threads are killed and that there are no outstanding requests.	949	that all threads are killed and that there are no outstanding requests.
713		950
714	Under normal circumstances you don't need to call this function.	951	Under normal circumstances you don't need to call this function.
715		952
716	=item $oldnreqs = IO::AIO::max_outstanding $nreqs	953	=item $oldmaxreqs = IO::AIO::max_outstanding $maxreqs
		954
		955	This is a very bad function to use in interactive programs because it
		956	blocks, and a bad way to reduce concurrency because it is inexact: Better
		957	use an C<aio_group> together with a feed callback.
717		958
718	Sets the maximum number of outstanding requests to C<$nreqs>. If you	959	Sets the maximum number of outstanding requests to C<$nreqs>. If you
719	try to queue up more than this number of requests, the caller will block until	960	to queue up more than this number of requests, the next call to the
720	some requests have been handled.	961	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
		962	function will block until the limit is no longer exceeded.
721		963
722	The default is very large, so normally there is no practical limit. If you	964	The default value is very large, so there is no practical limit on the
723	queue up many requests in a loop it often improves speed if you set	965	number of outstanding requests.
724	this to a relatively low number, such as C<100>.
725		966
726	Under normal circumstances you don't need to call this function.	967	You can still queue as many requests as you want. Therefore,
		968	C<max_oustsanding> is mainly useful in simple scripts (with low values) or
		969	as a stop gap to shield against fatal memory overflow (with large values).
727		970
728	=back	971	=back
729		972
730	=cut	973	=cut
731		974
…		…
743	or return undef;	986	or return undef;
744		987
745	*$sym	988	*$sym
746	}	989	}
747		990
748	min_parallel 4;	991	min_parallel 8;
749		992
750	END {	993	END {
751	max_parallel 0;	994	flush;
752	}	995	};
753		996
754	1;	997	1;
755		998
756	=head2 FORK BEHAVIOUR	999	=head2 FORK BEHAVIOUR
757		1000
758	This module should do "the right thing" when the process using it forks:	1001	This module should do "the right thing" when the process using it forks:
759		1002
760	Before the fork, IO::AIO enters a quiescent state where no requests	1003	Before the fork, IO::AIO enters a quiescent state where no requests
761	can be added in other threads and no results will be processed. After	1004	can be added in other threads and no results will be processed. After
762	the fork the parent simply leaves the quiescent state and continues	1005	the fork the parent simply leaves the quiescent state and continues
763	request/result processing, while the child clears the request/result	1006	request/result processing, while the child frees the request/result queue
764	queue (so the requests started before the fork will only be handled in	1007	(so that the requests started before the fork will only be handled in the
765	the parent). Threads will be started on demand until the limit ste in the	1008	parent). Threads will be started on demand until the limit set in the
766	parent process has been reached again.	1009	parent process has been reached again.
767		1010
768	In short: the parent will, after a short pause, continue as if fork had	1011	In short: the parent will, after a short pause, continue as if fork had
769	not been called, while the child will act as if IO::AIO has not been used	1012	not been called, while the child will act as if IO::AIO has not been used
770	yet.	1013	yet.
771		1014
		1015	=head2 MEMORY USAGE
		1016
		1017	Per-request usage:
		1018
		1019	Each aio request uses - depending on your architecture - around 100-200
		1020	bytes of memory. In addition, stat requests need a stat buffer (possibly
		1021	a few hundred bytes), readdir requires a result buffer and so on. Perl
		1022	scalars and other data passed into aio requests will also be locked and
		1023	will consume memory till the request has entered the done state.
		1024
		1025	This is now awfully much, so queuing lots of requests is not usually a
		1026	problem.
		1027
		1028	Per-thread usage:
		1029
		1030	In the execution phase, some aio requests require more memory for
		1031	temporary buffers, and each thread requires a stack and other data
		1032	structures (usually around 16k-128k, depending on the OS).
		1033
		1034	=head1 KNOWN BUGS
		1035
		1036	Known bugs will be fixed in the next release.
		1037
772	=head1 SEE ALSO	1038	=head1 SEE ALSO
773		1039
774	L<Coro>, L<Linux::AIO> (obsolete).	1040	L<Coro::AIO>.
775		1041
776	=head1 AUTHOR	1042	=head1 AUTHOR
777		1043
778	Marc Lehmann <schmorp@schmorp.de>	1044	Marc Lehmann <schmorp@schmorp.de>
779	http://home.schmorp.de/	1045	http://home.schmorp.de/

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Comparing IO-AIO/AIO.pm (file contents): Revision 1.56 by root, Sun Oct 22 00:53:47 2006 UTC vs. Revision 1.82 by root, Fri Oct 27 20:10:06 2006 UTC

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Revision 1.56 by root, Sun Oct 22 00:53:47 2006 UTC vs.
Revision 1.82 by root, Fri Oct 27 20:10:06 2006 UTC