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

Comparing IO-AIO/AIO.pm (file contents):
Revision 1.63 by root, Mon Oct 23 00:34:36 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 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).
		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
319	=item aio_link $srcpath, $dstpath, $callback->($status)	342	=item aio_link $srcpath, $dstpath, $callback->($status)
320		343
321	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
322	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.
323		346
…		…
343	sorted, and will B<NOT> include the C<.> and C<..> entries.	366	sorted, and will B<NOT> include the C<.> and C<..> entries.
344		367
345	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
346	with the filenames.	369	with the filenames.
347		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
348	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	473	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
349		474
350	[EXPERIMENTAL due to internal aio_group use]
351
352	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
353	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
354	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
355	recurse into (everything else).	478	recurse into (everything else, including symlinks to directories).
356		479
357	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_
358	C<$maxreq> specifies the maximum number of outstanding aio requests that	481	C<$maxreq> specifies the maximum number of outstanding aio requests that
359	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
360	will be chosen (currently 6).	483	will be chosen (currently 4).
361		484
362	On error, the callback is called without arguments, otherwise it receives	485	On error, the callback is called without arguments, otherwise it receives
363	two array-refs with path-relative entry names.	486	two array-refs with path-relative entry names.
364		487
365	Example:	488	Example:
…		…
402	=cut	525	=cut
403		526
404	sub aio_scandir($$$) {	527	sub aio_scandir($$$) {
405	my ($path, $maxreq, $cb) = @_;	528	my ($path, $maxreq, $cb) = @_;
406		529
		530	my $pri = aioreq_pri;
		531
407	my $grp = aio_group $cb;	532	my $grp = aio_group $cb;
408		533
409	$maxreq = 6 if $maxreq <= 0;	534	$maxreq = 4 if $maxreq <= 0;
410		535
411	# stat once	536	# stat once
		537	aioreq_pri $pri;
412	add $grp aio_stat $path, sub {	538	add $grp aio_stat $path, sub {
413	return $grp->result () if $_[0];	539	return $grp->result () if $_[0];
414	my $now = time;	540	my $now = time;
415	my $hash1 = join ":", (stat _)[0,1,3,7,9];	541	my $hash1 = join ":", (stat _)[0,1,3,7,9];
416		542
417	# read the directory entries	543	# read the directory entries
		544	aioreq_pri $pri;
418	add $grp aio_readdir $path, sub {	545	add $grp aio_readdir $path, sub {
419	my $entries = shift	546	my $entries = shift
420	or return $grp->result ();	547	or return $grp->result ();
421		548
422	# stat the dir another time	549	# stat the dir another time
		550	aioreq_pri $pri;
423	add $grp aio_stat $path, sub {	551	add $grp aio_stat $path, sub {
424	my $hash2 = join ":", (stat _)[0,1,3,7,9];	552	my $hash2 = join ":", (stat _)[0,1,3,7,9];
425		553
426	my $ndirs;	554	my $ndirs;
427		555
…		…
442	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],	570	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
443	@$entries];	571	@$entries];
444		572
445	my (@dirs, @nondirs);	573	my (@dirs, @nondirs);
446		574
447	my ($statcb, $schedcb);
448	my $nreq = 0;
449
450	my $statgrp = add $grp aio_group;	575	my $statgrp = add $grp aio_group sub {
		576	$grp->result (\@dirs, \@nondirs);
		577	};
451		578
452	$schedcb = sub {	579	limit $statgrp $maxreq;
453	if (@$entries) {	580	feed $statgrp sub {
454	if ($nreq < $maxreq) {	581	return unless @$entries;
455	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	}
456	$nreq++;	602	}
457	add $statgrp aio_stat "$path/$ent/.", sub { $statcb->($_[0], $ent) };
458	}	603	}
459	} elsif (!$nreq) {
460	# finished
461	$statgrp->cancel;
462	undef $statcb;
463	undef $schedcb;
464	$grp->result (\@dirs, \@nondirs);
465	}	604	};
466	};	605	};
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	};	606	};
497	};	607	};
498	};	608	};
499		609
500	$grp	610	$grp
…		…
513	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
514	detected, it will be emulated by calling C<fsync> instead.	624	detected, it will be emulated by calling C<fsync> instead.
515		625
516	=item aio_group $callback->(...)	626	=item aio_group $callback->(...)
517		627
518	[EXPERIMENTAL]
519
520	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
521	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
522	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.
523		632
524	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
525	for more info.	634	for more info.
526		635
527	Example:	636	Example:
…		…
540	This is a special request - it does nothing in itself and is only used for	649	This is a special request - it does nothing in itself and is only used for
541	side effects, such as when you want to add a dummy request to a group so	650	side effects, such as when you want to add a dummy request to a group so
542	that finishing the requests in the group depends on executing the given	651	that finishing the requests in the group depends on executing the given
543	code.	652	code.
544		653
		654	While this request does nothing, it still goes through the execution
		655	phase and still requires a worker thread. Thus, the callback will not
		656	be executed immediately but only after other requests in the queue have
		657	entered their execution phase. This can be used to measure request
		658	latency.
		659
545	=item IO::AIO::aio_sleep $fractional_seconds, $callback->() NOT EXPORTED	660	=item IO::AIO::aio_busy $fractional_seconds, $callback->() NOT EXPORTED
546		661
547	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
548	the request workers to sleep for the given time.	663	the request workers to sleep for the given time.
549		664
550	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
551	like sleep and file handle readable/writable, the overhead this creates	666	like sleep and file handle readable/writable, the overhead this creates is
552	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
553	under artificial I/O pressure.	668	except to put your application under artificial I/O pressure.
554		669
555	=back	670	=back
556		671
557	=head2 IO::AIO::REQ CLASS	672	=head2 IO::AIO::REQ CLASS
558		673
559	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
560	called in non-void context.	675	called in non-void context.
561		676
562	A request always moves through the following five states in its lifetime,
563	in order: B<ready> (request has been created, but has not been executed
564	yet), B<execute> (request is currently being executed), B<pending>
565	(request has been executed but callback has not been called yet),
566	B<result> (results are being processed synchronously, includes calling the
567	callback) and B<done> (request has reached the end of its lifetime and
568	holds no resources anymore).
569
570	=over 4	677	=over 4
571		678
572	=item $req->cancel	679	=item cancel $req
573		680
574	Cancels the request, if possible. Has the effect of skipping execution	681	Cancels the request, if possible. Has the effect of skipping execution
575	when entering the B<execute> state and skipping calling the callback when	682	when entering the B<execute> state and skipping calling the callback when
576	entering the the B<result> state, but will leave the request otherwise	683	entering the the B<result> state, but will leave the request otherwise
577	untouched. That means that requests that currently execute will not be	684	untouched. That means that requests that currently execute will not be
578	stopped and resources held by the request will not be freed prematurely.	685	stopped and resources held by the request will not be freed prematurely.
579		686
		687	=item cb $req $callback->(...)
		688
		689	Replace (or simply set) the callback registered to the request.
		690
580	=back	691	=back
581		692
582	=head2 IO::AIO::GRP CLASS	693	=head2 IO::AIO::GRP CLASS
583		694
584	This class is a subclass of L<IO::AIO::REQ>, so all its methods apply to	695	This class is a subclass of L<IO::AIO::REQ>, so all its methods apply to
…		…
623	=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.
624		735
625	=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
626	any later time).	737	any later time).
627		738
628	=item * This does not harmonise well with C<max_outstanding>, so best do
629	not combine C<aio_group> with it. Groups and feeders are recommended for
630	this kind of concurrency-limiting.
631
632	=back	739	=back
633		740
634	Their lifetime, simplified, looks like this: when they are empty, they	741	Their lifetime, simplified, looks like this: when they are empty, they
635	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
636	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
…		…
641	group. And only when all those requests have finished will the the group	748	group. And only when all those requests have finished will the the group
642	itself finish.	749	itself finish.
643		750
644	=over 4	751	=over 4
645		752
		753	=item add $grp ...
		754
646	=item $grp->add (...)	755	=item $grp->add (...)
647
648	=item add $grp ...
649		756
650	Add one or more requests to the group. Any type of L<IO::AIO::REQ> can	757	Add one or more requests to the group. Any type of L<IO::AIO::REQ> can
651	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
652	dependencies.	759	dependencies.
653		760
654	Returns all its arguments.	761	Returns all its arguments.
655		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
656	=item $grp->result (...)	768	=item $grp->result (...)
657		769
658	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
659	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.
660		774
661	=item $grp->set_feeder ($callback->($grp))	775	=item $grp->errno ([$errno])
662		776
663	[VERY EXPERIMENTAL]	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.
		786
		787	=item feed $grp $callback->($grp)
664		788
665	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
666	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,
667	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,
668	this might starve other requests for a potentially long time. For	792	this might starve other requests for a potentially long time. For
669	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>
670	requests, delaying any later requests for a long time.	794	requests, delaying any later requests for a long time.
671		795
672	To avoid this, and allow incremental generation of requests, you can	796	To avoid this, and allow incremental generation of requests, you can
673	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
674	feeder will be called whenever there are few enough (see C<feeder_limit>,	798	feed callback will be called whenever there are few enough (see C<limit>,
675	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
676	requests.	800	requests.
677		801
678	The feeder 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
679	impose any limits).	803	not impose any limits).
680		804
681	If the feeder does not queue more requests when called, it will be	805	If the feed does not queue more requests when called, it will be
682	automatically removed from the group.	806	automatically removed from the group.
683		807
684	If the feeder 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.
685		809
686	Example:	810	Example:
687		811
688	# 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:
689		813
690	my $grp = aio_group sub { print "finished\n" };	814	my $grp = aio_group sub { print "finished\n" };
691	$grp->feeder_limit (4);	815	limit $grp 4;
692	$grp->set_feeder (sub {	816	feed $grp sub {
693	my $file = pop @files	817	my $file = pop @files
694	or return;	818	or return;
695		819
696	add $grp aio_stat $file, sub { ... };	820	add $grp aio_stat $file, sub { ... };
697	});	821	};
698		822
699	=item $grp->feeder_limit ($num)	823	=item limit $grp $num
700		824
701	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
702	the group contains less than this many requests.	826	the group contains less than this many requests.
703		827
704	Setting the limit to C<0> will pause the feeding process.	828	Setting the limit to C<0> will pause the feeding process.
…		…
722		846
723	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
724	regularly. Returns the number of events processed. Returns immediately	848	regularly. Returns the number of events processed. Returns immediately
725	when no events are outstanding.	849	when no events are outstanding.
726		850
		851	If not all requests were processed for whatever reason, the filehandle
		852	will still be ready when C<poll_cb> returns.
		853
727	Example: Install an Event watcher that automatically calls	854	Example: Install an Event watcher that automatically calls
728	IO::AIO::poll_cb with high priority:	855	IO::AIO::poll_cb with high priority:
729		856
730	Event->io (fd => IO::AIO::poll_fileno,	857	Event->io (fd => IO::AIO::poll_fileno,
731	poll => 'r', async => 1,	858	poll => 'r', async => 1,
732	cb => \&IO::AIO::poll_cb);	859	cb => \&IO::AIO::poll_cb);
733		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
734	=item IO::AIO::poll_wait	877	=item IO::AIO::poll_wait
735		878
736	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
737	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
738	for some requests to finish).	881	for some requests to finish).
739		882
740	See C<nreqs> for an example.	883	See C<nreqs> for an example.
741		884
742	=item IO::AIO::nreqs	885	=item IO::AIO::nreqs
743		886
744	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
745	callback has not been invoked yet).	888	states (i.e. for which their callback has not been invoked yet).
746		889
747	Example: wait till there are no outstanding requests anymore:	890	Example: wait till there are no outstanding requests anymore:
748		891
749	IO::AIO::poll_wait, IO::AIO::poll_cb	892	IO::AIO::poll_wait, IO::AIO::poll_cb
750	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).
751		904
752	=item IO::AIO::flush	905	=item IO::AIO::flush
753		906
754	Wait till all outstanding AIO requests have been handled.	907	Wait till all outstanding AIO requests have been handled.
755		908
…		…
797	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
798	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.
799		952
800	Under normal circumstances you don't need to call this function.	953	Under normal circumstances you don't need to call this function.
801		954
802	=item $oldnreqs = IO::AIO::max_outstanding $nreqs	955	=item $oldmaxreqs = IO::AIO::max_outstanding $maxreqs
803		956
804	[DEPRECATED]	957	This is a very bad function to use in interactive programs because it
		958	blocks, and a bad way to reduce concurrency because it is inexact: Better
		959	use an C<aio_group> together with a feed callback.
805		960
806	Sets the maximum number of outstanding requests to C<$nreqs>. If you	961	Sets the maximum number of outstanding requests to C<$nreqs>. If you
807	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
808	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.
809		965
810	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
811	queue up many requests in a loop it often improves speed if you set	967	number of outstanding requests.
812	this to a relatively low number, such as C<100>.
813		968
814	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,
815	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
816	this function.	971	as a stop gap to shield against fatal memory overflow (with large values).
817
818	Under normal circumstances you don't need to call this function.
819		972
820	=back	973	=back
821		974
822	=cut	975	=cut
823		976
…		…
838	}	991	}
839		992
840	min_parallel 8;	993	min_parallel 8;
841		994
842	END {	995	END {
843	max_parallel 0;	996	flush;
844	}	997	};
845		998
846	1;	999	1;
847		1000
848	=head2 FORK BEHAVIOUR	1001	=head2 FORK BEHAVIOUR
849		1002
850	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:
851		1004
852	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
853	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
854	the fork the parent simply leaves the quiescent state and continues	1007	the fork the parent simply leaves the quiescent state and continues
855	request/result processing, while the child clears the request/result	1008	request/result processing, while the child frees the request/result queue
856	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
857	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
858	parent process has been reached again.	1011	parent process has been reached again.
859		1012
860	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
861	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
862	yet.	1015	yet.
863		1016
864	=head2 MEMORY USAGE	1017	=head2 MEMORY USAGE
865		1018
		1019	Per-request usage:
		1020
866	Each aio request uses - depending on your architecture - around 128 bytes	1021	Each aio request uses - depending on your architecture - around 100-200
867	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
868	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
869	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.
870		1026
871	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
872	problem.	1028	problem.
873		1029
874	Each thread needs a stack area which is usually around 16k, sometimes much	1030	Per-thread usage:
875	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.
876		1039
877	=head1 SEE ALSO	1040	=head1 SEE ALSO
878		1041
879	L<Coro>, L<Linux::AIO> (obsolete).	1042	L<Coro::AIO>.
880		1043
881	=head1 AUTHOR	1044	=head1 AUTHOR
882		1045
883	Marc Lehmann <schmorp@schmorp.de>	1046	Marc Lehmann <schmorp@schmorp.de>
884	http://home.schmorp.de/	1047	http://home.schmorp.de/

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Comparing IO-AIO/AIO.pm (file contents): Revision 1.63 by root, Mon Oct 23 00:34:36 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 1.63 by root, Mon Oct 23 00:34:36 2006 UTC vs.
Revision 1.83 by root, Fri Oct 27 20:11:58 2006 UTC