[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 1.82 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 perl, and	57	requests and signal their completion. You don't need thread support
57	the threads created by this module will not be visible to perl. In the	58	in perl, and the threads created by this module will not be visible
58	future, this module might make use of the native aio functions available	59	to perl. In the future, this module might make use of the native aio
59	on many operating systems. However, they are often not well-supported	60	functions available on many operating systems. However, they are often
60	(Linux doesn't allow them on normal files currently, for example),	61	not well-supported or restricted (Linux doesn't allow them on normal
61	and they would only support aio_read and aio_write, so the remaining	62	files currently, for example), and they would only support aio_read and
62	functionality would have to be implemented using threads anyway.	63	aio_write, so the remaining functionality would have to be implemented
		64	using threads anyway.
63		65
64	Although the module will work with in the presence of other threads, it is	66	Although the module will work with in the presence of other (Perl-)
65	currently not reentrant, so use appropriate locking yourself, always call	67	threads, it is currently not reentrant in any way, so use appropriate
66	C<poll_cb> from within the same thread, or never call C<poll_cb> (or other	68	locking yourself, always call C<poll_cb> from within the same thread, or
67	C<aio_> functions) recursively.	69	never call C<poll_cb> (or other C<aio_> functions) recursively.
		70
		71	=head1 REQUEST ANATOMY AND LIFETIME
		72
		73	Every C<aio_*> function creates a request. which is a C data structure not
		74	directly visible to Perl.
		75
		76	If called in non-void context, every request function returns a Perl
		77	object representing the request. In void context, nothing is returned,
		78	which saves a bit of memory.
		79
		80	The perl object is a fairly standard ref-to-hash object. The hash contents
		81	are not used by IO::AIO so you are free to store anything you like in it.
		82
		83	During their existance, aio requests travel through the following states,
		84	in order:
		85
		86	=over 4
		87
		88	=item ready
		89
		90	Immediately after a request is created it is put into the ready state,
		91	waiting for a thread to execute it.
		92
		93	=item execute
		94
		95	A thread has accepted the request for processing and is currently
		96	executing it (e.g. blocking in read).
		97
		98	=item pending
		99
		100	The request has been executed and is waiting for result processing.
		101
		102	While request submission and execution is fully asynchronous, result
		103	processing is not and relies on the perl interpreter calling C<poll_cb>
		104	(or another function with the same effect).
		105
		106	=item result
		107
		108	The request results are processed synchronously by C<poll_cb>.
		109
		110	The C<poll_cb> function will process all outstanding aio requests by
		111	calling their callbacks, freeing memory associated with them and managing
		112	any groups they are contained in.
		113
		114	=item done
		115
		116	Request has reached the end of its lifetime and holds no resources anymore
		117	(except possibly for the Perl object, but its connection to the actual
		118	aio request is severed and calling its methods will either do nothing or
		119	result in a runtime error).
68		120
69	=cut	121	=cut
70		122
71	package IO::AIO;	123	package IO::AIO;
72		124
…		…
79	our $VERSION = '2.0';	131	our $VERSION = '2.0';
80		132
81	our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close aio_stat	133	our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close aio_stat
82	aio_lstat aio_unlink aio_rmdir aio_readdir aio_scandir aio_symlink	134	aio_lstat aio_unlink aio_rmdir aio_readdir aio_scandir aio_symlink
83	aio_fsync aio_fdatasync aio_readahead aio_rename aio_link aio_move	135	aio_fsync aio_fdatasync aio_readahead aio_rename aio_link aio_move
84	aio_group aio_nop);	136	aio_copy aio_group aio_nop aio_mknod);
85	our @EXPORT = (@AIO_REQ, qw(aioreq_pri));	137	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
86	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush	138	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
87	min_parallel max_parallel max_outstanding nreqs);	139	min_parallel max_parallel nreqs nready npending);
88		140
89	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';	141	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';
90		142
91	require XSLoader;	143	require XSLoader;
92	XSLoader::load ("IO::AIO", $VERSION);	144	XSLoader::load ("IO::AIO", $VERSION);
…		…
123	environment, d) use Glib::filename_from_unicode on unicode filenames or e)	175	environment, d) use Glib::filename_from_unicode on unicode filenames or e)
124	use something else.	176	use something else.
125		177
126	=over 4	178	=over 4
127		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
128	=item aio_open $pathname, $flags, $mode, $callback->($fh)	211	=item aio_open $pathname, $flags, $mode, $callback->($fh)
129		212
130	Asynchronously open or create a file and call the callback with a newly	213	Asynchronously open or create a file and call the callback with a newly
131	created filehandle for the file.	214	created filehandle for the file.
132		215
…		…
181		264
182	aio_read $fh, 7, 15, $buffer, 0, sub {	265	aio_read $fh, 7, 15, $buffer, 0, sub {
183	$_[0] > 0 or die "read error: $!";	266	$_[0] > 0 or die "read error: $!";
184	print "read $_[0] bytes: <$buffer>\n";	267	print "read $_[0] bytes: <$buffer>\n";
185	};	268	};
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		269
257	=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)
258		271
259	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
260	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
…		…
316	=item aio_unlink $pathname, $callback->($status)	329	=item aio_unlink $pathname, $callback->($status)
317		330
318	Asynchronously unlink (delete) a file and call the callback with the	331	Asynchronously unlink (delete) a file and call the callback with the
319	result code.	332	result code.
320		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
321	=item aio_link $srcpath, $dstpath, $callback->($status)	340	=item aio_link $srcpath, $dstpath, $callback->($status)
322		341
323	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
324	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.
325		344
…		…
345	sorted, and will B<NOT> include the C<.> and C<..> entries.	364	sorted, and will B<NOT> include the C<.> and C<..> entries.
346		365
347	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
348	with the filenames.	367	with the filenames.
349		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
350	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	471	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
351		472
352	[EXPERIMENTAL due to internal aio_group use]
353
354	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
355	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
356	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
357	recurse into (everything else).	476	recurse into (everything else, including symlinks to directories).
358		477
359	C<aio_scandir> is a composite request that creates of many sub requests_	478	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	479	C<$maxreq> specifies the maximum number of outstanding aio requests that
361	this function generates. If it is C<< <= 0 >>, then a suitable default	480	this function generates. If it is C<< <= 0 >>, then a suitable default
362	will be chosen (currently 6).	481	will be chosen (currently 4).
363		482
364	On error, the callback is called without arguments, otherwise it receives	483	On error, the callback is called without arguments, otherwise it receives
365	two array-refs with path-relative entry names.	484	two array-refs with path-relative entry names.
366		485
367	Example:	486	Example:
…		…
404	=cut	523	=cut
405		524
406	sub aio_scandir($$$) {	525	sub aio_scandir($$$) {
407	my ($path, $maxreq, $cb) = @_;	526	my ($path, $maxreq, $cb) = @_;
408		527
		528	my $pri = aioreq_pri;
		529
409	my $grp = aio_group $cb;	530	my $grp = aio_group $cb;
410		531
411	$maxreq = 6 if $maxreq <= 0;	532	$maxreq = 4 if $maxreq <= 0;
412		533
413	# stat once	534	# stat once
		535	aioreq_pri $pri;
414	add $grp aio_stat $path, sub {	536	add $grp aio_stat $path, sub {
415	return $grp->result () if $_[0];	537	return $grp->result () if $_[0];
416	my $now = time;	538	my $now = time;
417	my $hash1 = join ":", (stat _)[0,1,3,7,9];	539	my $hash1 = join ":", (stat _)[0,1,3,7,9];
418		540
419	# read the directory entries	541	# read the directory entries
		542	aioreq_pri $pri;
420	add $grp aio_readdir $path, sub {	543	add $grp aio_readdir $path, sub {
421	my $entries = shift	544	my $entries = shift
422	or return $grp->result ();	545	or return $grp->result ();
423		546
424	# stat the dir another time	547	# stat the dir another time
		548	aioreq_pri $pri;
425	add $grp aio_stat $path, sub {	549	add $grp aio_stat $path, sub {
426	my $hash2 = join ":", (stat _)[0,1,3,7,9];	550	my $hash2 = join ":", (stat _)[0,1,3,7,9];
427		551
428	my $ndirs;	552	my $ndirs;
429		553
…		…
444	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],	568	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
445	@$entries];	569	@$entries];
446		570
447	my (@dirs, @nondirs);	571	my (@dirs, @nondirs);
448		572
449	my ($statcb, $schedcb);
450	my $nreq = 0;
451
452	my $statgrp = add $grp aio_group;	573	my $statgrp = add $grp aio_group sub {
		574	$grp->result (\@dirs, \@nondirs);
		575	};
453		576
454	$schedcb = sub {	577	limit $statgrp $maxreq;
455	if (@$entries) {	578	feed $statgrp sub {
456	if ($nreq < $maxreq) {	579	return unless @$entries;
457	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	}
458	$nreq++;	600	}
459	add $statgrp aio_stat "$path/$ent/.", sub { $statcb->($_[0], $ent) };
460	}	601	}
461	} elsif (!$nreq) {
462	# finished
463	$statgrp->cancel;
464	undef $statcb;
465	undef $schedcb;
466	$grp->result (\@dirs, \@nondirs);
467	}	602	};
468	};	603	};
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	};	604	};
499	};	605	};
500	};	606	};
501		607
502	$grp	608	$grp
…		…
515	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
516	detected, it will be emulated by calling C<fsync> instead.	622	detected, it will be emulated by calling C<fsync> instead.
517		623
518	=item aio_group $callback->(...)	624	=item aio_group $callback->(...)
519		625
520	[EXPERIMENTAL]
521
522	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
523	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
524	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.
525		630
526	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
527	for more info.	632	for more info.
528		633
529	Example:	634	Example:
…		…
548	phase and still requires a worker thread. Thus, the callback will not	653	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	654	be executed immediately but only after other requests in the queue have
550	entered their execution phase. This can be used to measure request	655	entered their execution phase. This can be used to measure request
551	latency.	656	latency.
552		657
553	=item IO::AIO::aio_sleep $fractional_seconds, $callback->() NOT EXPORTED	658	=item IO::AIO::aio_busy $fractional_seconds, $callback->() NOT EXPORTED
554		659
555	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
556	the request workers to sleep for the given time.	661	the request workers to sleep for the given time.
557		662
558	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
559	like sleep and file handle readable/writable, the overhead this creates	664	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	665	immense (it blocks a thread for a long time) so do not use this function
561	under artificial I/O pressure.	666	except to put your application under artificial I/O pressure.
562		667
563	=back	668	=back
564		669
565	=head2 IO::AIO::REQ CLASS	670	=head2 IO::AIO::REQ CLASS
566		671
567	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
568	called in non-void context.	673	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		674
578	=over 4	675	=over 4
579		676
580	=item cancel $req	677	=item cancel $req
581		678
…		…
635	=item * 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.
636		733
637	=item * You must not add requests to a group from within the group callback (or	734	=item * You must not add requests to a group from within the group callback (or
638	any later time).	735	any later time).
639		736
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	737	=back
645		738
646	Their lifetime, simplified, looks like this: when they are empty, they	739	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	740	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	741	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	756	be added, including other groups, as long as you do not create circular
664	dependencies.	757	dependencies.
665		758
666	Returns all its arguments.	759	Returns all its arguments.
667		760
		761	=item $grp->cancel_subs
		762
		763	Cancel all subrequests and clears any feeder, but not the group request
		764	itself. Useful when you queued a lot of events but got a result early.
		765
668	=item $grp->result (...)	766	=item $grp->result (...)
669		767
670	Set the result value(s) that will be passed to the group callback when all	768	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.	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.
672		784
673	=item feed $grp $callback->($grp)	785	=item feed $grp $callback->($grp)
674
675	[VERY EXPERIMENTAL]
676		786
677	Sets a feeder/generator on this group: every group can have an attached	787	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,	788	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,	789	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	790	this might starve other requests for a potentially long time. For
681	example, C<aio_scandir> might generate hundreds of thousands C<aio_stat>	791	example, C<aio_scandir> might generate hundreds of thousands C<aio_stat>
682	requests, delaying any later requests for a long time.	792	requests, delaying any later requests for a long time.
683		793
684	To avoid this, and allow incremental generation of requests, you can	794	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	795	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>,	796	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	797	below) requests active in the group itself and is expected to queue more
688	requests.	798	requests.
689		799
690	The feed can queue as many requests as it likes (i.e. C<add> does not	800	The feed callback can queue as many requests as it likes (i.e. C<add> does
691	impose any limits).	801	not impose any limits).
692		802
693	If the feed does not queue more requests when called, it will be	803	If the feed does not queue more requests when called, it will be
694	automatically removed from the group.	804	automatically removed from the group.
695		805
696	If the feed limit is C<0>, it will be set to C<2> automatically.	806	If the feed limit is C<0>, it will be set to C<2> automatically.
…		…
698	Example:	808	Example:
699		809
700	# stat all files in @files, but only ever use four aio requests concurrently:	810	# stat all files in @files, but only ever use four aio requests concurrently:
701		811
702	my $grp = aio_group sub { print "finished\n" };	812	my $grp = aio_group sub { print "finished\n" };
703	feed_limit $grp 4;	813	limit $grp 4;
704	feed $grp sub {	814	feed $grp sub {
705	my $file = pop @files	815	my $file = pop @files
706	or return;	816	or return;
707		817
708	add $grp aio_stat $file, sub { ... };	818	add $grp aio_stat $file, sub { ... };
709	};	819	};
710		820
711	=item feed_limit $grp $num	821	=item limit $grp $num
712		822
713	Sets the feeder limit for the group: The feeder will be called whenever	823	Sets the feeder limit for the group: The feeder will be called whenever
714	the group contains less than this many requests.	824	the group contains less than this many requests.
715		825
716	Setting the limit to C<0> will pause the feeding process.	826	Setting the limit to C<0> will pause the feeding process.
…		…
734		844
735	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
736	regularly. Returns the number of events processed. Returns immediately	846	regularly. Returns the number of events processed. Returns immediately
737	when no events are outstanding.	847	when no events are outstanding.
738		848
		849	If not all requests were processed for whatever reason, the filehandle
		850	will still be ready when C<poll_cb> returns.
		851
739	Example: Install an Event watcher that automatically calls	852	Example: Install an Event watcher that automatically calls
740	IO::AIO::poll_cb with high priority:	853	IO::AIO::poll_cb with high priority:
741		854
742	Event->io (fd => IO::AIO::poll_fileno,	855	Event->io (fd => IO::AIO::poll_fileno,
743	poll => 'r', async => 1,	856	poll => 'r', async => 1,
744	cb => \&IO::AIO::poll_cb);	857	cb => \&IO::AIO::poll_cb);
745		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
746	=item IO::AIO::poll_wait	875	=item IO::AIO::poll_wait
747		876
748	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
749	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
750	for some requests to finish).	879	for some requests to finish).
751		880
752	See C<nreqs> for an example.	881	See C<nreqs> for an example.
753		882
754	=item IO::AIO::nreqs	883	=item IO::AIO::nreqs
755		884
756	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
757	callback has not been invoked yet).	886	states (i.e. for which their callback has not been invoked yet).
758		887
759	Example: wait till there are no outstanding requests anymore:	888	Example: wait till there are no outstanding requests anymore:
760		889
761	IO::AIO::poll_wait, IO::AIO::poll_cb	890	IO::AIO::poll_wait, IO::AIO::poll_cb
762	while IO::AIO::nreqs;	891	while IO::AIO::nreqs;
		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).
763		902
764	=item IO::AIO::flush	903	=item IO::AIO::flush
765		904
766	Wait till all outstanding AIO requests have been handled.	905	Wait till all outstanding AIO requests have been handled.
767		906
…		…
809	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
810	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.
811		950
812	Under normal circumstances you don't need to call this function.	951	Under normal circumstances you don't need to call this function.
813		952
814	=item $oldnreqs = IO::AIO::max_outstanding $nreqs	953	=item $oldmaxreqs = IO::AIO::max_outstanding $maxreqs
815		954
816	[DEPRECATED]	955	This is a very bad function to use in interactive programs because it
		956	blocks, and a bad way to reduce concurrency because it is inexact: Better
		957	use an C<aio_group> together with a feed callback.
817		958
818	Sets the maximum number of outstanding requests to C<$nreqs>. If you	959	Sets the maximum number of outstanding requests to C<$nreqs>. If you
819	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
820	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.
821		963
822	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
823	queue up many requests in a loop it often improves speed if you set	965	number of outstanding requests.
824	this to a relatively low number, such as C<100>.
825		966
826	This function does not work well together with C<aio_group>'s, and their	967	You can still queue as many requests as you want. Therefore,
827	feeder interface is better suited to limiting concurrency, so do not use	968	C<max_oustsanding> is mainly useful in simple scripts (with low values) or
828	this function.	969	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		970
832	=back	971	=back
833		972
834	=cut	973	=cut
835		974
…		…
850	}	989	}
851		990
852	min_parallel 8;	991	min_parallel 8;
853		992
854	END {	993	END {
855	max_parallel 0;	994	flush;
856	}	995	};
857		996
858	1;	997	1;
859		998
860	=head2 FORK BEHAVIOUR	999	=head2 FORK BEHAVIOUR
861		1000
862	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:
863		1002
864	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
865	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
866	the fork the parent simply leaves the quiescent state and continues	1005	the fork the parent simply leaves the quiescent state and continues
867	request/result processing, while the child clears the request/result	1006	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	1007	(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	1008	parent). Threads will be started on demand until the limit set in the
870	parent process has been reached again.	1009	parent process has been reached again.
871		1010
872	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
873	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
874	yet.	1013	yet.
875		1014
876	=head2 MEMORY USAGE	1015	=head2 MEMORY USAGE
877		1016
		1017	Per-request usage:
		1018
878	Each aio request uses - depending on your architecture - around 128 bytes	1019	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	1020	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	1021	a few hundred bytes), readdir requires a result buffer and so on. Perl
881	also be locked.	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.
882		1024
883	This is now awfully much, so queuing lots of requests is not usually a	1025	This is now awfully much, so queuing lots of requests is not usually a
884	problem.	1026	problem.
885		1027
886	Each thread needs a stack area which is usually around 16k, sometimes much	1028	Per-thread usage:
887	larger, depending on the OS.	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.
888		1037
889	=head1 SEE ALSO	1038	=head1 SEE ALSO
890		1039
891	L<Coro>, L<Linux::AIO> (obsolete).	1040	L<Coro::AIO>.
892		1041
893	=head1 AUTHOR	1042	=head1 AUTHOR
894		1043
895	Marc Lehmann <schmorp@schmorp.de>	1044	Marc Lehmann <schmorp@schmorp.de>
896	http://home.schmorp.de/	1045	http://home.schmorp.de/

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Comparing IO-AIO/AIO.pm (file contents): Revision 1.67 by root, Tue Oct 24 02:25:16 2006 UTC vs. Revision 1.82 by root, Fri Oct 27 20:10:06 2006 UTC

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Comparing IO-AIO/AIO.pm (file contents):
Revision 1.67 by root, Tue Oct 24 02:25:16 2006 UTC vs.
Revision 1.82 by root, Fri Oct 27 20:10:06 2006 UTC