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

Comparing IO-AIO/AIO.pm (file contents):
Revision 1.65 by root, Mon Oct 23 14:49:51 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 aio_nop);	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	[EXPERIMENTAL due to internal aio_group use]
188
189	Try to move the I<file> (directories not supported as either source or
190	destination) from C<$srcpath> to C<$dstpath> and call the callback with
191	the C<0> (error) or C<-1> ok.
192
193	This is a composite request that tries to rename(2) the file first. If
194	rename files with C<EXDEV>, it creates the destination file with mode 0200
195	and copies the contents of the source file into it using C<aio_sendfile>,
196	followed by restoring atime, mtime, access mode and uid/gid, in that
197	order, and unlinking the C<$srcpath>.
198
199	If an error occurs, the partial destination file will be unlinked, if
200	possible, except when setting atime, mtime, access mode and uid/gid, where
201	errors are being ignored.
202
203	=cut
204
205	sub aio_move($$$) {
206	my ($src, $dst, $cb) = @_;
207
208	my $grp = aio_group $cb;
209
210	add $grp aio_rename $src, $dst, sub {
211	if ($_[0] && $! == EXDEV) {
212	add $grp aio_open $src, O_RDONLY, 0, sub {
213	if (my $src_fh = $_[0]) {
214	my @stat = stat $src_fh;
215
216	add $grp aio_open $dst, O_WRONLY, 0200, sub {
217	if (my $dst_fh = $_[0]) {
218	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
219	close $src_fh;
220
221	if ($_[0] == $stat[7]) {
222	utime $stat[8], $stat[9], $dst;
223	chmod $stat[2] & 07777, $dst_fh;
224	chown $stat[4], $stat[5], $dst_fh;
225	close $dst_fh;
226
227	add $grp aio_unlink $src, sub {
228	$grp->result ($_[0]);
229	};
230	} else {
231	my $errno = $!;
232	add $grp aio_unlink $dst, sub {
233	$! = $errno;
234	$grp->result (-1);
235	};
236	}
237	};
238	} else {
239	$grp->result (-1);
240	}
241	},
242
243	} else {
244	$grp->result (-1);
245	}
246	};
247	} else {
248	$grp->result ($_[0]);
249	}
250	};
251
252	$grp
253	}
254		269
255	=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)
256		271
257	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
258	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
…		…
314	=item aio_unlink $pathname, $callback->($status)	329	=item aio_unlink $pathname, $callback->($status)
315		330
316	Asynchronously unlink (delete) a file and call the callback with the	331	Asynchronously unlink (delete) a file and call the callback with the
317	result code.	332	result code.
318		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
319	=item aio_link $srcpath, $dstpath, $callback->($status)	340	=item aio_link $srcpath, $dstpath, $callback->($status)
320		341
321	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
322	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.
323		344
…		…
343	sorted, and will B<NOT> include the C<.> and C<..> entries.	364	sorted, and will B<NOT> include the C<.> and C<..> entries.
344		365
345	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
346	with the filenames.	367	with the filenames.
347		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
348	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	471	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
349		472
350	[EXPERIMENTAL due to internal aio_group use]
351
352	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
353	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
354	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
355	recurse into (everything else).	476	recurse into (everything else, including symlinks to directories).
356		477
357	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_
358	C<$maxreq> specifies the maximum number of outstanding aio requests that	479	C<$maxreq> specifies the maximum number of outstanding aio requests that
359	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
360	will be chosen (currently 6).	481	will be chosen (currently 4).
361		482
362	On error, the callback is called without arguments, otherwise it receives	483	On error, the callback is called without arguments, otherwise it receives
363	two array-refs with path-relative entry names.	484	two array-refs with path-relative entry names.
364		485
365	Example:	486	Example:
…		…
402	=cut	523	=cut
403		524
404	sub aio_scandir($$$) {	525	sub aio_scandir($$$) {
405	my ($path, $maxreq, $cb) = @_;	526	my ($path, $maxreq, $cb) = @_;
406		527
		528	my $pri = aioreq_pri;
		529
407	my $grp = aio_group $cb;	530	my $grp = aio_group $cb;
408		531
409	$maxreq = 6 if $maxreq <= 0;	532	$maxreq = 4 if $maxreq <= 0;
410		533
411	# stat once	534	# stat once
		535	aioreq_pri $pri;
412	add $grp aio_stat $path, sub {	536	add $grp aio_stat $path, sub {
413	return $grp->result () if $_[0];	537	return $grp->result () if $_[0];
414	my $now = time;	538	my $now = time;
415	my $hash1 = join ":", (stat _)[0,1,3,7,9];	539	my $hash1 = join ":", (stat _)[0,1,3,7,9];
416		540
417	# read the directory entries	541	# read the directory entries
		542	aioreq_pri $pri;
418	add $grp aio_readdir $path, sub {	543	add $grp aio_readdir $path, sub {
419	my $entries = shift	544	my $entries = shift
420	or return $grp->result ();	545	or return $grp->result ();
421		546
422	# stat the dir another time	547	# stat the dir another time
		548	aioreq_pri $pri;
423	add $grp aio_stat $path, sub {	549	add $grp aio_stat $path, sub {
424	my $hash2 = join ":", (stat _)[0,1,3,7,9];	550	my $hash2 = join ":", (stat _)[0,1,3,7,9];
425		551
426	my $ndirs;	552	my $ndirs;
427		553
…		…
442	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],	568	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
443	@$entries];	569	@$entries];
444		570
445	my (@dirs, @nondirs);	571	my (@dirs, @nondirs);
446		572
447	my ($statcb, $schedcb);
448	my $nreq = 0;
449
450	my $statgrp = add $grp aio_group;	573	my $statgrp = add $grp aio_group sub {
		574	$grp->result (\@dirs, \@nondirs);
		575	};
451		576
452	$schedcb = sub {	577	limit $statgrp $maxreq;
453	if (@$entries) {	578	feed $statgrp sub {
454	if ($nreq < $maxreq) {	579	return unless @$entries;
455	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	}
456	$nreq++;	600	}
457	add $statgrp aio_stat "$path/$ent/.", sub { $statcb->($_[0], $ent) };
458	}	601	}
459	} elsif (!$nreq) {
460	# finished
461	$statgrp->cancel;
462	undef $statcb;
463	undef $schedcb;
464	$grp->result (\@dirs, \@nondirs);
465	}	602	};
466	};	603	};
467	$statcb = sub {
468	my ($status, $entry) = @_;
469
470	if ($status < 0) {
471	$nreq--;
472	push @nondirs, $entry;
473	&$schedcb;
474	} else {
475	# need to check for real directory
476	add $grp aio_lstat "$path/$entry", sub {
477	$nreq--;
478
479	if (-d _) {
480	push @dirs, $entry;
481
482	if (!--$ndirs) {
483	push @nondirs, @$entries;
484	$entries = [];
485	}
486	} else {
487	push @nondirs, $entry;
488	}
489
490	&$schedcb;
491	}
492	}
493	};
494
495	&$schedcb while @$entries && $nreq < $maxreq;
496	};	604	};
497	};	605	};
498	};	606	};
499		607
500	$grp	608	$grp
…		…
513	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
514	detected, it will be emulated by calling C<fsync> instead.	622	detected, it will be emulated by calling C<fsync> instead.
515		623
516	=item aio_group $callback->(...)	624	=item aio_group $callback->(...)
517		625
518	[EXPERIMENTAL]
519
520	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
521	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
522	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.
523		630
524	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
525	for more info.	632	for more info.
526		633
527	Example:	634	Example:
…		…
546	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
547	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
548	entered their execution phase. This can be used to measure request	655	entered their execution phase. This can be used to measure request
549	latency.	656	latency.
550		657
551	=item IO::AIO::aio_sleep $fractional_seconds, $callback->() NOT EXPORTED	658	=item IO::AIO::aio_busy $fractional_seconds, $callback->() NOT EXPORTED
552		659
553	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
554	the request workers to sleep for the given time.	661	the request workers to sleep for the given time.
555		662
556	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
557	like sleep and file handle readable/writable, the overhead this creates	664	like sleep and file handle readable/writable, the overhead this creates is
558	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
559	under artificial I/O pressure.	666	except to put your application under artificial I/O pressure.
560		667
561	=back	668	=back
562		669
563	=head2 IO::AIO::REQ CLASS	670	=head2 IO::AIO::REQ CLASS
564		671
565	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
566	called in non-void context.	673	called in non-void context.
567
568	A request always moves through the following five states in its lifetime,
569	in order: B<ready> (request has been created, but has not been executed
570	yet), B<execute> (request is currently being executed), B<pending>
571	(request has been executed but callback has not been called yet),
572	B<result> (results are being processed synchronously, includes calling the
573	callback) and B<done> (request has reached the end of its lifetime and
574	holds no resources anymore).
575		674
576	=over 4	675	=over 4
577		676
578	=item cancel $req	677	=item cancel $req
579		678
…		…
633	=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.
634		733
635	=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
636	any later time).	735	any later time).
637		736
638	=item * This does not harmonise well with C<max_outstanding>, so best do
639	not combine C<aio_group> with it. Groups and feeders are recommended for
640	this kind of concurrency-limiting.
641
642	=back	737	=back
643		738
644	Their lifetime, simplified, looks like this: when they are empty, they	739	Their lifetime, simplified, looks like this: when they are empty, they
645	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
646	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
…		…
661	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
662	dependencies.	757	dependencies.
663		758
664	Returns all its arguments.	759	Returns all its arguments.
665		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
666	=item $grp->result (...)	766	=item $grp->result (...)
667		767
668	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
669	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.
670		784
671	=item feed $grp $callback->($grp)	785	=item feed $grp $callback->($grp)
672
673	[VERY EXPERIMENTAL]
674		786
675	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
676	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,
677	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,
678	this might starve other requests for a potentially long time. For	790	this might starve other requests for a potentially long time. For
679	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>
680	requests, delaying any later requests for a long time.	792	requests, delaying any later requests for a long time.
681		793
682	To avoid this, and allow incremental generation of requests, you can	794	To avoid this, and allow incremental generation of requests, you can
683	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
684	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>,
685	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
686	requests.	798	requests.
687		799
688	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
689	impose any limits).	801	not impose any limits).
690		802
691	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
692	automatically removed from the group.	804	automatically removed from the group.
693		805
694	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.
…		…
696	Example:	808	Example:
697		809
698	# 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:
699		811
700	my $grp = aio_group sub { print "finished\n" };	812	my $grp = aio_group sub { print "finished\n" };
701	feed_limit $grp 4;	813	limit $grp 4;
702	feed $grp sub {	814	feed $grp sub {
703	my $file = pop @files	815	my $file = pop @files
704	or return;	816	or return;
705		817
706	add $grp aio_stat $file, sub { ... };	818	add $grp aio_stat $file, sub { ... };
707	};	819	};
708		820
709	=item feed_limit $grp $num	821	=item limit $grp $num
710		822
711	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
712	the group contains less than this many requests.	824	the group contains less than this many requests.
713		825
714	Setting the limit to C<0> will pause the feeding process.	826	Setting the limit to C<0> will pause the feeding process.
…		…
732		844
733	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
734	regularly. Returns the number of events processed. Returns immediately	846	regularly. Returns the number of events processed. Returns immediately
735	when no events are outstanding.	847	when no events are outstanding.
736		848
		849	If not all requests were processed for whatever reason, the filehandle
		850	will still be ready when C<poll_cb> returns.
		851
737	Example: Install an Event watcher that automatically calls	852	Example: Install an Event watcher that automatically calls
738	IO::AIO::poll_cb with high priority:	853	IO::AIO::poll_cb with high priority:
739		854
740	Event->io (fd => IO::AIO::poll_fileno,	855	Event->io (fd => IO::AIO::poll_fileno,
741	poll => 'r', async => 1,	856	poll => 'r', async => 1,
742	cb => \&IO::AIO::poll_cb);	857	cb => \&IO::AIO::poll_cb);
743		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
744	=item IO::AIO::poll_wait	875	=item IO::AIO::poll_wait
745		876
746	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
747	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
748	for some requests to finish).	879	for some requests to finish).
749		880
750	See C<nreqs> for an example.	881	See C<nreqs> for an example.
751		882
752	=item IO::AIO::nreqs	883	=item IO::AIO::nreqs
753		884
754	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
755	callback has not been invoked yet).	886	states (i.e. for which their callback has not been invoked yet).
756		887
757	Example: wait till there are no outstanding requests anymore:	888	Example: wait till there are no outstanding requests anymore:
758		889
759	IO::AIO::poll_wait, IO::AIO::poll_cb	890	IO::AIO::poll_wait, IO::AIO::poll_cb
760	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).
761		902
762	=item IO::AIO::flush	903	=item IO::AIO::flush
763		904
764	Wait till all outstanding AIO requests have been handled.	905	Wait till all outstanding AIO requests have been handled.
765		906
…		…
807	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
808	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.
809		950
810	Under normal circumstances you don't need to call this function.	951	Under normal circumstances you don't need to call this function.
811		952
812	=item $oldnreqs = IO::AIO::max_outstanding $nreqs	953	=item $oldmaxreqs = IO::AIO::max_outstanding $maxreqs
813		954
814	[DEPRECATED]	955	This is a very bad function to use in interactive programs because it
		956	blocks, and a bad way to reduce concurrency because it is inexact: Better
		957	use an C<aio_group> together with a feed callback.
815		958
816	Sets the maximum number of outstanding requests to C<$nreqs>. If you	959	Sets the maximum number of outstanding requests to C<$nreqs>. If you
817	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
818	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.
819		963
820	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
821	queue up many requests in a loop it often improves speed if you set	965	number of outstanding requests.
822	this to a relatively low number, such as C<100>.
823		966
824	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,
825	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
826	this function.	969	as a stop gap to shield against fatal memory overflow (with large values).
827
828	Under normal circumstances you don't need to call this function.
829		970
830	=back	971	=back
831		972
832	=cut	973	=cut
833		974
…		…
848	}	989	}
849		990
850	min_parallel 8;	991	min_parallel 8;
851		992
852	END {	993	END {
853	max_parallel 0;	994	flush;
854	}	995	};
855		996
856	1;	997	1;
857		998
858	=head2 FORK BEHAVIOUR	999	=head2 FORK BEHAVIOUR
859		1000
860	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:
861		1002
862	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
863	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
864	the fork the parent simply leaves the quiescent state and continues	1005	the fork the parent simply leaves the quiescent state and continues
865	request/result processing, while the child clears the request/result	1006	request/result processing, while the child frees the request/result queue
866	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
867	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
868	parent process has been reached again.	1009	parent process has been reached again.
869		1010
870	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
871	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
872	yet.	1013	yet.
873		1014
874	=head2 MEMORY USAGE	1015	=head2 MEMORY USAGE
875		1016
		1017	Per-request usage:
		1018
876	Each aio request uses - depending on your architecture - around 128 bytes	1019	Each aio request uses - depending on your architecture - around 100-200
877	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
878	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
879	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.
880		1024
881	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
882	problem.	1026	problem.
883		1027
884	Each thread needs a stack area which is usually around 16k, sometimes much	1028	Per-thread usage:
885	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.
886		1037
887	=head1 SEE ALSO	1038	=head1 SEE ALSO
888		1039
889	L<Coro>, L<Linux::AIO> (obsolete).	1040	L<Coro::AIO>.
890		1041
891	=head1 AUTHOR	1042	=head1 AUTHOR
892		1043
893	Marc Lehmann <schmorp@schmorp.de>	1044	Marc Lehmann <schmorp@schmorp.de>
894	http://home.schmorp.de/	1045	http://home.schmorp.de/

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Comparing IO-AIO/AIO.pm (file contents): Revision 1.65 by root, Mon Oct 23 14:49:51 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 1.65 by root, Mon Oct 23 14:49:51 2006 UTC vs.
Revision 1.82 by root, Fri Oct 27 20:10:06 2006 UTC