[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 1.83 by root, Fri Oct 27 20:11:58 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).
		337
		338	The only portable (POSIX) way of calling this function is:
		339
		340	aio_mknod $path, IO::AIO::S_IFIFO \| $mode, 0, sub { ...
		341
321	=item aio_link $srcpath, $dstpath, $callback->($status)	342	=item aio_link $srcpath, $dstpath, $callback->($status)
322		343
323	Asynchronously create a new link to the existing object at C<$srcpath> at	344	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.	345	the path C<$dstpath> and call the callback with the result code.
325		346
…		…
345	sorted, and will B<NOT> include the C<.> and C<..> entries.	366	sorted, and will B<NOT> include the C<.> and C<..> entries.
346		367
347	The callback a single argument which is either C<undef> or an array-ref	368	The callback a single argument which is either C<undef> or an array-ref
348	with the filenames.	369	with the filenames.
349		370
		371	=item aio_copy $srcpath, $dstpath, $callback->($status)
		372
		373	Try to copy the I<file> (directories not supported as either source or
		374	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		375	the C<0> (error) or C<-1> ok.
		376
		377	This is a composite request that it creates the destination file with
		378	mode 0200 and copies the contents of the source file into it using
		379	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
		380	uid/gid, in that order.
		381
		382	If an error occurs, the partial destination file will be unlinked, if
		383	possible, except when setting atime, mtime, access mode and uid/gid, where
		384	errors are being ignored.
		385
		386	=cut
		387
		388	sub aio_copy($$;$) {
		389	my ($src, $dst, $cb) = @_;
		390
		391	my $pri = aioreq_pri;
		392	my $grp = aio_group $cb;
		393
		394	aioreq_pri $pri;
		395	add $grp aio_open $src, O_RDONLY, 0, sub {
		396	if (my $src_fh = $_[0]) {
		397	my @stat = stat $src_fh;
		398
		399	aioreq_pri $pri;
		400	add $grp aio_open $dst, O_CREAT \| O_WRONLY \| O_TRUNC, 0200, sub {
		401	if (my $dst_fh = $_[0]) {
		402	aioreq_pri $pri;
		403	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
		404	if ($_[0] == $stat[7]) {
		405	$grp->result (0);
		406	close $src_fh;
		407
		408	# those should not normally block. should. should.
		409	utime $stat[8], $stat[9], $dst;
		410	chmod $stat[2] & 07777, $dst_fh;
		411	chown $stat[4], $stat[5], $dst_fh;
		412	close $dst_fh;
		413	} else {
		414	$grp->result (-1);
		415	close $src_fh;
		416	close $dst_fh;
		417
		418	aioreq $pri;
		419	add $grp aio_unlink $dst;
		420	}
		421	};
		422	} else {
		423	$grp->result (-1);
		424	}
		425	},
		426
		427	} else {
		428	$grp->result (-1);
		429	}
		430	};
		431
		432	$grp
		433	}
		434
		435	=item aio_move $srcpath, $dstpath, $callback->($status)
		436
		437	Try to move the I<file> (directories not supported as either source or
		438	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		439	the C<0> (error) or C<-1> ok.
		440
		441	This is a composite request that tries to rename(2) the file first. If
		442	rename files with C<EXDEV>, it copies the file with C<aio_copy> and, if
		443	that is successful, unlinking the C<$srcpath>.
		444
		445	=cut
		446
		447	sub aio_move($$;$) {
		448	my ($src, $dst, $cb) = @_;
		449
		450	my $pri = aioreq_pri;
		451	my $grp = aio_group $cb;
		452
		453	aioreq_pri $pri;
		454	add $grp aio_rename $src, $dst, sub {
		455	if ($_[0] && $! == EXDEV) {
		456	aioreq_pri $pri;
		457	add $grp aio_copy $src, $dst, sub {
		458	$grp->result ($_[0]);
		459
		460	if (!$_[0]) {
		461	aioreq_pri $pri;
		462	add $grp aio_unlink $src;
		463	}
		464	};
		465	} else {
		466	$grp->result ($_[0]);
		467	}
		468	};
		469
		470	$grp
		471	}
		472
350	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	473	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
351		474
352	[EXPERIMENTAL due to internal aio_group use]
353
354	Scans a directory (similar to C<aio_readdir>) but additionally tries to	475	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	476	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	477	names, directories you can recurse into (directories), and ones you cannot
357	recurse into (everything else).	478	recurse into (everything else, including symlinks to directories).
358		479
359	C<aio_scandir> is a composite request that creates of many sub requests_	480	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	481	C<$maxreq> specifies the maximum number of outstanding aio requests that
361	this function generates. If it is C<< <= 0 >>, then a suitable default	482	this function generates. If it is C<< <= 0 >>, then a suitable default
362	will be chosen (currently 6).	483	will be chosen (currently 4).
363		484
364	On error, the callback is called without arguments, otherwise it receives	485	On error, the callback is called without arguments, otherwise it receives
365	two array-refs with path-relative entry names.	486	two array-refs with path-relative entry names.
366		487
367	Example:	488	Example:
…		…
404	=cut	525	=cut
405		526
406	sub aio_scandir($$$) {	527	sub aio_scandir($$$) {
407	my ($path, $maxreq, $cb) = @_;	528	my ($path, $maxreq, $cb) = @_;
408		529
		530	my $pri = aioreq_pri;
		531
409	my $grp = aio_group $cb;	532	my $grp = aio_group $cb;
410		533
411	$maxreq = 6 if $maxreq <= 0;	534	$maxreq = 4 if $maxreq <= 0;
412		535
413	# stat once	536	# stat once
		537	aioreq_pri $pri;
414	add $grp aio_stat $path, sub {	538	add $grp aio_stat $path, sub {
415	return $grp->result () if $_[0];	539	return $grp->result () if $_[0];
416	my $now = time;	540	my $now = time;
417	my $hash1 = join ":", (stat _)[0,1,3,7,9];	541	my $hash1 = join ":", (stat _)[0,1,3,7,9];
418		542
419	# read the directory entries	543	# read the directory entries
		544	aioreq_pri $pri;
420	add $grp aio_readdir $path, sub {	545	add $grp aio_readdir $path, sub {
421	my $entries = shift	546	my $entries = shift
422	or return $grp->result ();	547	or return $grp->result ();
423		548
424	# stat the dir another time	549	# stat the dir another time
		550	aioreq_pri $pri;
425	add $grp aio_stat $path, sub {	551	add $grp aio_stat $path, sub {
426	my $hash2 = join ":", (stat _)[0,1,3,7,9];	552	my $hash2 = join ":", (stat _)[0,1,3,7,9];
427		553
428	my $ndirs;	554	my $ndirs;
429		555
…		…
444	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],	570	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
445	@$entries];	571	@$entries];
446		572
447	my (@dirs, @nondirs);	573	my (@dirs, @nondirs);
448		574
449	my ($statcb, $schedcb);
450	my $nreq = 0;
451
452	my $statgrp = add $grp aio_group;	575	my $statgrp = add $grp aio_group sub {
		576	$grp->result (\@dirs, \@nondirs);
		577	};
453		578
454	$schedcb = sub {	579	limit $statgrp $maxreq;
455	if (@$entries) {	580	feed $statgrp sub {
456	if ($nreq < $maxreq) {	581	return unless @$entries;
457	my $ent = pop @$entries;	582	my $entry = pop @$entries;
		583
		584	aioreq_pri $pri;
		585	add $statgrp aio_stat "$path/$entry/.", sub {
		586	if ($_[0] < 0) {
		587	push @nondirs, $entry;
		588	} else {
		589	# need to check for real directory
		590	aioreq_pri $pri;
		591	add $statgrp aio_lstat "$path/$entry", sub {
		592	if (-d _) {
		593	push @dirs, $entry;
		594
		595	unless (--$ndirs) {
		596	push @nondirs, @$entries;
		597	feed $statgrp;
		598	}
		599	} else {
		600	push @nondirs, $entry;
		601	}
458	$nreq++;	602	}
459	add $statgrp aio_stat "$path/$ent/.", sub { $statcb->($_[0], $ent) };
460	}	603	}
461	} elsif (!$nreq) {
462	# finished
463	$statgrp->cancel;
464	undef $statcb;
465	undef $schedcb;
466	$grp->result (\@dirs, \@nondirs);
467	}	604	};
468	};	605	};
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	};	606	};
499	};	607	};
500	};	608	};
501		609
502	$grp	610	$grp
…		…
515	If this call isn't available because your OS lacks it or it couldn't be	623	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.	624	detected, it will be emulated by calling C<fsync> instead.
517		625
518	=item aio_group $callback->(...)	626	=item aio_group $callback->(...)
519		627
520	[EXPERIMENTAL]
521
522	This is a very special aio request: Instead of doing something, it is a	628	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	629	container for other aio requests, which is useful if you want to bundle
524	many requests into a single, composite, request.	630	many requests into a single, composite, request with a definite callback
		631	and the ability to cancel the whole request with its subrequests.
525		632
526	Returns an object of class L<IO::AIO::GRP>. See its documentation below	633	Returns an object of class L<IO::AIO::GRP>. See its documentation below
527	for more info.	634	for more info.
528		635
529	Example:	636	Example:
…		…
548	phase and still requires a worker thread. Thus, the callback will not	655	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	656	be executed immediately but only after other requests in the queue have
550	entered their execution phase. This can be used to measure request	657	entered their execution phase. This can be used to measure request
551	latency.	658	latency.
552		659
553	=item IO::AIO::aio_sleep $fractional_seconds, $callback->() NOT EXPORTED	660	=item IO::AIO::aio_busy $fractional_seconds, $callback->() NOT EXPORTED
554		661
555	Mainly used for debugging and benchmarking, this aio request puts one of	662	Mainly used for debugging and benchmarking, this aio request puts one of
556	the request workers to sleep for the given time.	663	the request workers to sleep for the given time.
557		664
558	While it is theoretically handy to have simple I/O scheduling requests	665	While it is theoretically handy to have simple I/O scheduling requests
559	like sleep and file handle readable/writable, the overhead this creates	666	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	667	immense (it blocks a thread for a long time) so do not use this function
561	under artificial I/O pressure.	668	except to put your application under artificial I/O pressure.
562		669
563	=back	670	=back
564		671
565	=head2 IO::AIO::REQ CLASS	672	=head2 IO::AIO::REQ CLASS
566		673
567	All non-aggregate C<aio_*> functions return an object of this class when	674	All non-aggregate C<aio_*> functions return an object of this class when
568	called in non-void context.	675	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		676
578	=over 4	677	=over 4
579		678
580	=item cancel $req	679	=item cancel $req
581		680
…		…
635	=item * They can also can also be added to other IO::AIO::GRP objects.	734	=item * They can also can also be added to other IO::AIO::GRP objects.
636		735
637	=item * You must not add requests to a group from within the group callback (or	736	=item * You must not add requests to a group from within the group callback (or
638	any later time).	737	any later time).
639		738
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	739	=back
645		740
646	Their lifetime, simplified, looks like this: when they are empty, they	741	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	742	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	743	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	758	be added, including other groups, as long as you do not create circular
664	dependencies.	759	dependencies.
665		760
666	Returns all its arguments.	761	Returns all its arguments.
667		762
		763	=item $grp->cancel_subs
		764
		765	Cancel all subrequests and clears any feeder, but not the group request
		766	itself. Useful when you queued a lot of events but got a result early.
		767
668	=item $grp->result (...)	768	=item $grp->result (...)
669		769
670	Set the result value(s) that will be passed to the group callback when all	770	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.	771	subrequests have finished and set thre groups errno to the current value
		772	of errno (just like calling C<errno> without an error number). By default,
		773	no argument will be passed and errno is zero.
		774
		775	=item $grp->errno ([$errno])
		776
		777	Sets the group errno value to C<$errno>, or the current value of errno
		778	when the argument is missing.
		779
		780	Every aio request has an associated errno value that is restored when
		781	the callback is invoked. This method lets you change this value from its
		782	default (0).
		783
		784	Calling C<result> will also set errno, so make sure you either set C<$!>
		785	before the call to C<result>, or call c<errno> after it.
672		786
673	=item feed $grp $callback->($grp)	787	=item feed $grp $callback->($grp)
674
675	[VERY EXPERIMENTAL]
676		788
677	Sets a feeder/generator on this group: every group can have an attached	789	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,	790	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,	791	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	792	this might starve other requests for a potentially long time. For
681	example, C<aio_scandir> might generate hundreds of thousands C<aio_stat>	793	example, C<aio_scandir> might generate hundreds of thousands C<aio_stat>
682	requests, delaying any later requests for a long time.	794	requests, delaying any later requests for a long time.
683		795
684	To avoid this, and allow incremental generation of requests, you can	796	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	797	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>,	798	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	799	below) requests active in the group itself and is expected to queue more
688	requests.	800	requests.
689		801
690	The feed can queue as many requests as it likes (i.e. C<add> does not	802	The feed callback can queue as many requests as it likes (i.e. C<add> does
691	impose any limits).	803	not impose any limits).
692		804
693	If the feed does not queue more requests when called, it will be	805	If the feed does not queue more requests when called, it will be
694	automatically removed from the group.	806	automatically removed from the group.
695		807
696	If the feed limit is C<0>, it will be set to C<2> automatically.	808	If the feed limit is C<0>, it will be set to C<2> automatically.
…		…
698	Example:	810	Example:
699		811
700	# stat all files in @files, but only ever use four aio requests concurrently:	812	# stat all files in @files, but only ever use four aio requests concurrently:
701		813
702	my $grp = aio_group sub { print "finished\n" };	814	my $grp = aio_group sub { print "finished\n" };
703	feed_limit $grp 4;	815	limit $grp 4;
704	feed $grp sub {	816	feed $grp sub {
705	my $file = pop @files	817	my $file = pop @files
706	or return;	818	or return;
707		819
708	add $grp aio_stat $file, sub { ... };	820	add $grp aio_stat $file, sub { ... };
709	};	821	};
710		822
711	=item feed_limit $grp $num	823	=item limit $grp $num
712		824
713	Sets the feeder limit for the group: The feeder will be called whenever	825	Sets the feeder limit for the group: The feeder will be called whenever
714	the group contains less than this many requests.	826	the group contains less than this many requests.
715		827
716	Setting the limit to C<0> will pause the feeding process.	828	Setting the limit to C<0> will pause the feeding process.
…		…
734		846
735	Process all outstanding events on the result pipe. You have to call this	847	Process all outstanding events on the result pipe. You have to call this
736	regularly. Returns the number of events processed. Returns immediately	848	regularly. Returns the number of events processed. Returns immediately
737	when no events are outstanding.	849	when no events are outstanding.
738		850
		851	If not all requests were processed for whatever reason, the filehandle
		852	will still be ready when C<poll_cb> returns.
		853
739	Example: Install an Event watcher that automatically calls	854	Example: Install an Event watcher that automatically calls
740	IO::AIO::poll_cb with high priority:	855	IO::AIO::poll_cb with high priority:
741		856
742	Event->io (fd => IO::AIO::poll_fileno,	857	Event->io (fd => IO::AIO::poll_fileno,
743	poll => 'r', async => 1,	858	poll => 'r', async => 1,
744	cb => \&IO::AIO::poll_cb);	859	cb => \&IO::AIO::poll_cb);
745		860
		861	=item IO::AIO::poll_some $max_requests
		862
		863	Similar to C<poll_cb>, but only processes up to C<$max_requests> requests
		864	at a time.
		865
		866	Useful if you want to ensure some level of interactiveness when perl is
		867	not fast enough to process all requests in time.
		868
		869	Example: Install an Event watcher that automatically calls
		870	IO::AIO::poll_some with low priority, to ensure that other parts of the
		871	program get the CPU sometimes even under high AIO load.
		872
		873	Event->io (fd => IO::AIO::poll_fileno,
		874	poll => 'r', nice => 1,
		875	cb => sub { IO::AIO::poll_some 256 });
		876
746	=item IO::AIO::poll_wait	877	=item IO::AIO::poll_wait
747		878
748	Wait till the result filehandle becomes ready for reading (simply does a	879	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	880	C<select> on the filehandle. This is useful if you want to synchronously wait
750	for some requests to finish).	881	for some requests to finish).
751		882
752	See C<nreqs> for an example.	883	See C<nreqs> for an example.
753		884
754	=item IO::AIO::nreqs	885	=item IO::AIO::nreqs
755		886
756	Returns the number of requests currently outstanding (i.e. for which their	887	Returns the number of requests currently in the ready, execute or pending
757	callback has not been invoked yet).	888	states (i.e. for which their callback has not been invoked yet).
758		889
759	Example: wait till there are no outstanding requests anymore:	890	Example: wait till there are no outstanding requests anymore:
760		891
761	IO::AIO::poll_wait, IO::AIO::poll_cb	892	IO::AIO::poll_wait, IO::AIO::poll_cb
762	while IO::AIO::nreqs;	893	while IO::AIO::nreqs;
		894
		895	=item IO::AIO::nready
		896
		897	Returns the number of requests currently in the ready state (not yet
		898	executed).
		899
		900	=item IO::AIO::npending
		901
		902	Returns the number of requests currently in the pending state (executed,
		903	but not yet processed by poll_cb).
763		904
764	=item IO::AIO::flush	905	=item IO::AIO::flush
765		906
766	Wait till all outstanding AIO requests have been handled.	907	Wait till all outstanding AIO requests have been handled.
767		908
…		…
809	This module automatically runs C<max_parallel 0> at program end, to ensure	950	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.	951	that all threads are killed and that there are no outstanding requests.
811		952
812	Under normal circumstances you don't need to call this function.	953	Under normal circumstances you don't need to call this function.
813		954
814	=item $oldnreqs = IO::AIO::max_outstanding $nreqs	955	=item $oldmaxreqs = IO::AIO::max_outstanding $maxreqs
815		956
816	[DEPRECATED]	957	This is a very bad function to use in interactive programs because it
		958	blocks, and a bad way to reduce concurrency because it is inexact: Better
		959	use an C<aio_group> together with a feed callback.
817		960
818	Sets the maximum number of outstanding requests to C<$nreqs>. If you	961	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	962	to queue up more than this number of requests, the next call to the
820	some requests have been handled.	963	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
		964	function will block until the limit is no longer exceeded.
821		965
822	The default is very large, so normally there is no practical limit. If you	966	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	967	number of outstanding requests.
824	this to a relatively low number, such as C<100>.
825		968
826	This function does not work well together with C<aio_group>'s, and their	969	You can still queue as many requests as you want. Therefore,
827	feeder interface is better suited to limiting concurrency, so do not use	970	C<max_oustsanding> is mainly useful in simple scripts (with low values) or
828	this function.	971	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		972
832	=back	973	=back
833		974
834	=cut	975	=cut
835		976
…		…
850	}	991	}
851		992
852	min_parallel 8;	993	min_parallel 8;
853		994
854	END {	995	END {
855	max_parallel 0;	996	flush;
856	}	997	};
857		998
858	1;	999	1;
859		1000
860	=head2 FORK BEHAVIOUR	1001	=head2 FORK BEHAVIOUR
861		1002
862	This module should do "the right thing" when the process using it forks:	1003	This module should do "the right thing" when the process using it forks:
863		1004
864	Before the fork, IO::AIO enters a quiescent state where no requests	1005	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	1006	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	1007	the fork the parent simply leaves the quiescent state and continues
867	request/result processing, while the child clears the request/result	1008	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	1009	(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	1010	parent). Threads will be started on demand until the limit set in the
870	parent process has been reached again.	1011	parent process has been reached again.
871		1012
872	In short: the parent will, after a short pause, continue as if fork had	1013	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	1014	not been called, while the child will act as if IO::AIO has not been used
874	yet.	1015	yet.
875		1016
876	=head2 MEMORY USAGE	1017	=head2 MEMORY USAGE
877		1018
		1019	Per-request usage:
		1020
878	Each aio request uses - depending on your architecture - around 128 bytes	1021	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	1022	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	1023	a few hundred bytes), readdir requires a result buffer and so on. Perl
881	also be locked.	1024	scalars and other data passed into aio requests will also be locked and
		1025	will consume memory till the request has entered the done state.
882		1026
883	This is now awfully much, so queuing lots of requests is not usually a	1027	This is now awfully much, so queuing lots of requests is not usually a
884	problem.	1028	problem.
885		1029
886	Each thread needs a stack area which is usually around 16k, sometimes much	1030	Per-thread usage:
887	larger, depending on the OS.	1031
		1032	In the execution phase, some aio requests require more memory for
		1033	temporary buffers, and each thread requires a stack and other data
		1034	structures (usually around 16k-128k, depending on the OS).
		1035
		1036	=head1 KNOWN BUGS
		1037
		1038	Known bugs will be fixed in the next release.
888		1039
889	=head1 SEE ALSO	1040	=head1 SEE ALSO
890		1041
891	L<Coro>, L<Linux::AIO> (obsolete).	1042	L<Coro::AIO>.
892		1043
893	=head1 AUTHOR	1044	=head1 AUTHOR
894		1045
895	Marc Lehmann <schmorp@schmorp.de>	1046	Marc Lehmann <schmorp@schmorp.de>
896	http://home.schmorp.de/	1047	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 1.83 by root, Fri Oct 27 20:11:58 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 1.83 by root, Fri Oct 27 20:11:58 2006 UTC