[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 1.87 by root, Sun Oct 29 00:52:02 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
		56	Asynchronous means that operations that can normally block your program
		57	(e.g. reading from disk) will be done asynchronously: the operation
		58	will still block, but you can do something else in the meantime. This
		59	is extremely useful for programs that need to stay interactive even
		60	when doing heavy I/O (GUI programs, high performance network servers
		61	etc.), but can also be used to easily do operations in parallel that are
		62	normally done sequentially, e.g. stat'ing many files, which is much faster
		63	on a RAID volume or over NFS when you do a number of stat operations
		64	concurrently.
		65
		66	While this works on all types of file descriptors (for example sockets),
		67	using these functions on file descriptors that support nonblocking
		68	operation (again, sockets, pipes etc.) is very inefficient. Use an event
		69	loop for that (such as the L<Event\|Event> module): IO::AIO will naturally
		70	fit into such an event loop itself.
		71
55	Currently, a number of threads are started that execute your read/writes	72	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	73	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	74	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	75	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	76	functions available on many operating systems. However, they are often
60	not well-supported (Linux doesn't allow them on normal files currently,	77	not well-supported or restricted (GNU/Linux doesn't allow them on normal
61	for example), and they would only support aio_read and aio_write, so the	78	files currently, for example), and they would only support aio_read and
62	remaining functionality would have to be implemented using threads anyway.	79	aio_write, so the remaining functionality would have to be implemented
		80	using threads anyway.
63		81
64	Although the module will work with in the presence of other threads, it is	82	Although the module will work with in the presence of other (Perl-)
65	currently not reentrant, so use appropriate locking yourself, always call	83	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	84	locking yourself, always call C<poll_cb> from within the same thread, or
67	C<aio_> functions) recursively.	85	never call C<poll_cb> (or other C<aio_> functions) recursively.
		86
		87	=head2 EXAMPLE
		88
		89	This is a simple example that uses the Event module and loads
		90	F</etc/passwd> asynchronously:
		91
		92	use Fcntl;
		93	use Event;
		94	use IO::AIO;
		95
		96	# register the IO::AIO callback with Event
		97	Event->io (fd => IO::AIO::poll_fileno,
		98	poll => 'r',
		99	cb => \&IO::AIO::poll_cb);
		100
		101	# queue the request to open /etc/passwd
		102	aio_open "/etc/passwd", O_RDONLY, 0, sub {
		103	my $fh = $_[0]
		104	or die "error while opening: $!";
		105
		106	# stat'ing filehandles is generally non-blocking
		107	my $size = -s $fh;
		108
		109	# queue a request to read the file
		110	my $contents;
		111	aio_read $fh, 0, $size, $contents, 0, sub {
		112	$_[0] == $size
		113	or die "short read: $!";
		114
		115	close $fh;
		116
		117	# file contents now in $contents
		118	print $contents;
		119
		120	# exit event loop and program
		121	Event::unloop;
		122	};
		123	};
		124
		125	# possibly queue up other requests, or open GUI windows,
		126	# check for sockets etc. etc.
		127
		128	# process events as long as there are some:
		129	Event::loop;
		130
		131	=head1 REQUEST ANATOMY AND LIFETIME
		132
		133	Every C<aio_*> function creates a request. which is a C data structure not
		134	directly visible to Perl.
		135
		136	If called in non-void context, every request function returns a Perl
		137	object representing the request. In void context, nothing is returned,
		138	which saves a bit of memory.
		139
		140	The perl object is a fairly standard ref-to-hash object. The hash contents
		141	are not used by IO::AIO so you are free to store anything you like in it.
		142
		143	During their existance, aio requests travel through the following states,
		144	in order:
		145
		146	=over 4
		147
		148	=item ready
		149
		150	Immediately after a request is created it is put into the ready state,
		151	waiting for a thread to execute it.
		152
		153	=item execute
		154
		155	A thread has accepted the request for processing and is currently
		156	executing it (e.g. blocking in read).
		157
		158	=item pending
		159
		160	The request has been executed and is waiting for result processing.
		161
		162	While request submission and execution is fully asynchronous, result
		163	processing is not and relies on the perl interpreter calling C<poll_cb>
		164	(or another function with the same effect).
		165
		166	=item result
		167
		168	The request results are processed synchronously by C<poll_cb>.
		169
		170	The C<poll_cb> function will process all outstanding aio requests by
		171	calling their callbacks, freeing memory associated with them and managing
		172	any groups they are contained in.
		173
		174	=item done
		175
		176	Request has reached the end of its lifetime and holds no resources anymore
		177	(except possibly for the Perl object, but its connection to the actual
		178	aio request is severed and calling its methods will either do nothing or
		179	result in a runtime error).
68		180
69	=cut	181	=cut
70		182
71	package IO::AIO;	183	package IO::AIO;
72		184
…		…
74	use strict 'vars';	186	use strict 'vars';
75		187
76	use base 'Exporter';	188	use base 'Exporter';
77		189
78	BEGIN {	190	BEGIN {
79	our $VERSION = '2.0';	191	our $VERSION = '2.1';
80		192
81	our @EXPORT = qw(aio_sendfile aio_read aio_write aio_open aio_close aio_stat	193	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	194	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	195	aio_fsync aio_fdatasync aio_readahead aio_rename aio_link aio_move
84	aio_group aio_nop);	196	aio_copy aio_group aio_nop aio_mknod);
85	our @EXPORT_OK = qw(poll_fileno poll_cb min_parallel max_parallel max_outstanding nreqs);	197	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
		198	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
		199	min_parallel max_parallel max_idle
		200	nreqs nready npending nthreads
		201	max_poll_time max_poll_reqs);
86		202
87	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';	203	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';
88		204
89	require XSLoader;	205	require XSLoader;
90	XSLoader::load ("IO::AIO", $VERSION);	206	XSLoader::load ("IO::AIO", $VERSION);
91	}	207	}
92		208
93	=head1 FUNCTIONS	209	=head1 FUNCTIONS
94		210
95	=head2 AIO FUNCTIONS	211	=head2 AIO REQUEST FUNCTIONS
96		212
97	All the C<aio_*> calls are more or less thin wrappers around the syscall	213	All the C<aio_*> calls are more or less thin wrappers around the syscall
98	with the same name (sans C<aio_>). The arguments are similar or identical,	214	with the same name (sans C<aio_>). The arguments are similar or identical,
99	and they all accept an additional (and optional) C<$callback> argument	215	and they all accept an additional (and optional) C<$callback> argument
100	which must be a code reference. This code reference will get called with	216	which must be a code reference. This code reference will get called with
…		…
103	syscall has been executed asynchronously.	219	syscall has been executed asynchronously.
104		220
105	All functions expecting a filehandle keep a copy of the filehandle	221	All functions expecting a filehandle keep a copy of the filehandle
106	internally until the request has finished.	222	internally until the request has finished.
107		223
108	All requests return objects of type L<IO::AIO::REQ> that allow further	224	All functions return request objects of type L<IO::AIO::REQ> that allow
109	manipulation of those requests while they are in-flight.	225	further manipulation of those requests while they are in-flight.
110		226
111	The pathnames you pass to these routines I<must> be absolute and	227	The pathnames you pass to these routines I<must> be absolute and
112	encoded in byte form. The reason for the former is that at the time the	228	encoded as octets. The reason for the former is that at the time the
113	request is being executed, the current working directory could have	229	request is being executed, the current working directory could have
114	changed. Alternatively, you can make sure that you never change the	230	changed. Alternatively, you can make sure that you never change the
115	current working directory.	231	current working directory anywhere in the program and then use relative
		232	paths.
116		233
117	To encode pathnames to byte form, either make sure you either: a)	234	To encode pathnames as octets, either make sure you either: a) always pass
118	always pass in filenames you got from outside (command line, readdir	235	in filenames you got from outside (command line, readdir etc.) without
119	etc.), b) are ASCII or ISO 8859-1, c) use the Encode module and encode	236	tinkering, b) are ASCII or ISO 8859-1, c) use the Encode module and encode
120	your pathnames to the locale (or other) encoding in effect in the user	237	your pathnames to the locale (or other) encoding in effect in the user
121	environment, d) use Glib::filename_from_unicode on unicode filenames or e)	238	environment, d) use Glib::filename_from_unicode on unicode filenames or e)
122	use something else.	239	use something else to ensure your scalar has the correct contents.
		240
		241	This works, btw. independent of the internal UTF-8 bit, which IO::AIO
		242	handles correctly wether it is set or not.
123		243
124	=over 4	244	=over 4
		245
		246	=item $prev_pri = aioreq_pri [$pri]
		247
		248	Returns the priority value that would be used for the next request and, if
		249	C<$pri> is given, sets the priority for the next aio request.
		250
		251	The default priority is C<0>, the minimum and maximum priorities are C<-4>
		252	and C<4>, respectively. Requests with higher priority will be serviced
		253	first.
		254
		255	The priority will be reset to C<0> after each call to one of the C<aio_*>
		256	functions.
		257
		258	Example: open a file with low priority, then read something from it with
		259	higher priority so the read request is serviced before other low priority
		260	open requests (potentially spamming the cache):
		261
		262	aioreq_pri -3;
		263	aio_open ..., sub {
		264	return unless $_[0];
		265
		266	aioreq_pri -2;
		267	aio_read $_[0], ..., sub {
		268	...
		269	};
		270	};
		271
		272	=item aioreq_nice $pri_adjust
		273
		274	Similar to C<aioreq_pri>, but subtracts the given value from the current
		275	priority, so the effect is cumulative.
125		276
126	=item aio_open $pathname, $flags, $mode, $callback->($fh)	277	=item aio_open $pathname, $flags, $mode, $callback->($fh)
127		278
128	Asynchronously open or create a file and call the callback with a newly	279	Asynchronously open or create a file and call the callback with a newly
129	created filehandle for the file.	280	created filehandle for the file.
…		…
179		330
180	aio_read $fh, 7, 15, $buffer, 0, sub {	331	aio_read $fh, 7, 15, $buffer, 0, sub {
181	$_[0] > 0 or die "read error: $!";	332	$_[0] > 0 or die "read error: $!";
182	print "read $_[0] bytes: <$buffer>\n";	333	print "read $_[0] bytes: <$buffer>\n";
183	};	334	};
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		335
255	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)	336	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
256		337
257	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts	338	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	339	reading at byte offset C<$in_offset>, and starts writing at the current
…		…
314	=item aio_unlink $pathname, $callback->($status)	395	=item aio_unlink $pathname, $callback->($status)
315		396
316	Asynchronously unlink (delete) a file and call the callback with the	397	Asynchronously unlink (delete) a file and call the callback with the
317	result code.	398	result code.
318		399
		400	=item aio_mknod $path, $mode, $dev, $callback->($status)
		401
		402	[EXPERIMENTAL]
		403
		404	Asynchronously create a device node (or fifo). See mknod(2).
		405
		406	The only (POSIX-) portable way of calling this function is:
		407
		408	aio_mknod $path, IO::AIO::S_IFIFO \| $mode, 0, sub { ...
		409
319	=item aio_link $srcpath, $dstpath, $callback->($status)	410	=item aio_link $srcpath, $dstpath, $callback->($status)
320		411
321	Asynchronously create a new link to the existing object at C<$srcpath> at	412	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.	413	the path C<$dstpath> and call the callback with the result code.
323		414
…		…
343	sorted, and will B<NOT> include the C<.> and C<..> entries.	434	sorted, and will B<NOT> include the C<.> and C<..> entries.
344		435
345	The callback a single argument which is either C<undef> or an array-ref	436	The callback a single argument which is either C<undef> or an array-ref
346	with the filenames.	437	with the filenames.
347		438
		439	=item aio_copy $srcpath, $dstpath, $callback->($status)
		440
		441	Try to copy the I<file> (directories not supported as either source or
		442	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		443	the C<0> (error) or C<-1> ok.
		444
		445	This is a composite request that it creates the destination file with
		446	mode 0200 and copies the contents of the source file into it using
		447	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
		448	uid/gid, in that order.
		449
		450	If an error occurs, the partial destination file will be unlinked, if
		451	possible, except when setting atime, mtime, access mode and uid/gid, where
		452	errors are being ignored.
		453
		454	=cut
		455
		456	sub aio_copy($$;$) {
		457	my ($src, $dst, $cb) = @_;
		458
		459	my $pri = aioreq_pri;
		460	my $grp = aio_group $cb;
		461
		462	aioreq_pri $pri;
		463	add $grp aio_open $src, O_RDONLY, 0, sub {
		464	if (my $src_fh = $_[0]) {
		465	my @stat = stat $src_fh;
		466
		467	aioreq_pri $pri;
		468	add $grp aio_open $dst, O_CREAT \| O_WRONLY \| O_TRUNC, 0200, sub {
		469	if (my $dst_fh = $_[0]) {
		470	aioreq_pri $pri;
		471	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
		472	if ($_[0] == $stat[7]) {
		473	$grp->result (0);
		474	close $src_fh;
		475
		476	# those should not normally block. should. should.
		477	utime $stat[8], $stat[9], $dst;
		478	chmod $stat[2] & 07777, $dst_fh;
		479	chown $stat[4], $stat[5], $dst_fh;
		480	close $dst_fh;
		481	} else {
		482	$grp->result (-1);
		483	close $src_fh;
		484	close $dst_fh;
		485
		486	aioreq $pri;
		487	add $grp aio_unlink $dst;
		488	}
		489	};
		490	} else {
		491	$grp->result (-1);
		492	}
		493	},
		494
		495	} else {
		496	$grp->result (-1);
		497	}
		498	};
		499
		500	$grp
		501	}
		502
		503	=item aio_move $srcpath, $dstpath, $callback->($status)
		504
		505	Try to move the I<file> (directories not supported as either source or
		506	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		507	the C<0> (error) or C<-1> ok.
		508
		509	This is a composite request that tries to rename(2) the file first. If
		510	rename files with C<EXDEV>, it copies the file with C<aio_copy> and, if
		511	that is successful, unlinking the C<$srcpath>.
		512
		513	=cut
		514
		515	sub aio_move($$;$) {
		516	my ($src, $dst, $cb) = @_;
		517
		518	my $pri = aioreq_pri;
		519	my $grp = aio_group $cb;
		520
		521	aioreq_pri $pri;
		522	add $grp aio_rename $src, $dst, sub {
		523	if ($_[0] && $! == EXDEV) {
		524	aioreq_pri $pri;
		525	add $grp aio_copy $src, $dst, sub {
		526	$grp->result ($_[0]);
		527
		528	if (!$_[0]) {
		529	aioreq_pri $pri;
		530	add $grp aio_unlink $src;
		531	}
		532	};
		533	} else {
		534	$grp->result ($_[0]);
		535	}
		536	};
		537
		538	$grp
		539	}
		540
348	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	541	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
349		542
350	[EXPERIMENTAL due to internal aio_group use]
351
352	Scans a directory (similar to C<aio_readdir>) but additionally tries to	543	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	544	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	545	names, directories you can recurse into (directories), and ones you cannot
355	recurse into (everything else).	546	recurse into (everything else, including symlinks to directories).
356		547
357	C<aio_scandir> is a composite request that creates of many sub requests_	548	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	549	C<$maxreq> specifies the maximum number of outstanding aio requests that
359	this function generates. If it is C<< <= 0 >>, then a suitable default	550	this function generates. If it is C<< <= 0 >>, then a suitable default
360	will be chosen (currently 6).	551	will be chosen (currently 4).
361		552
362	On error, the callback is called without arguments, otherwise it receives	553	On error, the callback is called without arguments, otherwise it receives
363	two array-refs with path-relative entry names.	554	two array-refs with path-relative entry names.
364		555
365	Example:	556	Example:
…		…
402	=cut	593	=cut
403		594
404	sub aio_scandir($$$) {	595	sub aio_scandir($$$) {
405	my ($path, $maxreq, $cb) = @_;	596	my ($path, $maxreq, $cb) = @_;
406		597
		598	my $pri = aioreq_pri;
		599
407	my $grp = aio_group $cb;	600	my $grp = aio_group $cb;
408		601
409	$maxreq = 6 if $maxreq <= 0;	602	$maxreq = 4 if $maxreq <= 0;
410		603
411	# stat once	604	# stat once
		605	aioreq_pri $pri;
412	add $grp aio_stat $path, sub {	606	add $grp aio_stat $path, sub {
413	return $grp->result () if $_[0];	607	return $grp->result () if $_[0];
414	my $now = time;	608	my $now = time;
415	my $hash1 = join ":", (stat _)[0,1,3,7,9];	609	my $hash1 = join ":", (stat _)[0,1,3,7,9];
416		610
417	# read the directory entries	611	# read the directory entries
		612	aioreq_pri $pri;
418	add $grp aio_readdir $path, sub {	613	add $grp aio_readdir $path, sub {
419	my $entries = shift	614	my $entries = shift
420	or return $grp->result ();	615	or return $grp->result ();
421		616
422	# stat the dir another time	617	# stat the dir another time
		618	aioreq_pri $pri;
423	add $grp aio_stat $path, sub {	619	add $grp aio_stat $path, sub {
424	my $hash2 = join ":", (stat _)[0,1,3,7,9];	620	my $hash2 = join ":", (stat _)[0,1,3,7,9];
425		621
426	my $ndirs;	622	my $ndirs;
427		623
…		…
442	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],	638	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
443	@$entries];	639	@$entries];
444		640
445	my (@dirs, @nondirs);	641	my (@dirs, @nondirs);
446		642
447	my ($statcb, $schedcb);
448	my $nreq = 0;
449
450	my $statgrp = add $grp aio_group;	643	my $statgrp = add $grp aio_group sub {
		644	$grp->result (\@dirs, \@nondirs);
		645	};
451		646
452	$schedcb = sub {	647	limit $statgrp $maxreq;
453	if (@$entries) {	648	feed $statgrp sub {
454	if ($nreq < $maxreq) {	649	return unless @$entries;
455	my $ent = pop @$entries;	650	my $entry = pop @$entries;
		651
		652	aioreq_pri $pri;
		653	add $statgrp aio_stat "$path/$entry/.", sub {
		654	if ($_[0] < 0) {
		655	push @nondirs, $entry;
		656	} else {
		657	# need to check for real directory
		658	aioreq_pri $pri;
		659	add $statgrp aio_lstat "$path/$entry", sub {
		660	if (-d _) {
		661	push @dirs, $entry;
		662
		663	unless (--$ndirs) {
		664	push @nondirs, @$entries;
		665	feed $statgrp;
		666	}
		667	} else {
		668	push @nondirs, $entry;
		669	}
456	$nreq++;	670	}
457	add $statgrp aio_stat "$path/$ent/.", sub { $statcb->($_[0], $ent) };
458	}	671	}
459	} elsif (!$nreq) {
460	# finished
461	$statgrp->cancel;
462	undef $statcb;
463	undef $schedcb;
464	$grp->result (\@dirs, \@nondirs);
465	}	672	};
466	};	673	};
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	};	674	};
497	};	675	};
498	};	676	};
499		677
500	$grp	678	$grp
…		…
513	If this call isn't available because your OS lacks it or it couldn't be	691	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.	692	detected, it will be emulated by calling C<fsync> instead.
515		693
516	=item aio_group $callback->(...)	694	=item aio_group $callback->(...)
517		695
518	[EXPERIMENTAL]
519
520	This is a very special aio request: Instead of doing something, it is a	696	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	697	container for other aio requests, which is useful if you want to bundle
522	many requests into a single, composite, request.	698	many requests into a single, composite, request with a definite callback
		699	and the ability to cancel the whole request with its subrequests.
523		700
524	Returns an object of class L<IO::AIO::GRP>. See its documentation below	701	Returns an object of class L<IO::AIO::GRP>. See its documentation below
525	for more info.	702	for more info.
526		703
527	Example:	704	Example:
…		…
540	This is a special request - it does nothing in itself and is only used for	717	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	718	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	719	that finishing the requests in the group depends on executing the given
543	code.	720	code.
544		721
		722	While this request does nothing, it still goes through the execution
		723	phase and still requires a worker thread. Thus, the callback will not
		724	be executed immediately but only after other requests in the queue have
		725	entered their execution phase. This can be used to measure request
		726	latency.
		727
545	=item IO::AIO::aio_sleep $fractional_seconds, $callback->() NOT EXPORTED	728	=item IO::AIO::aio_busy $fractional_seconds, $callback->() NOT EXPORTED
546		729
547	Mainly used for debugging and benchmarking, this aio request puts one of	730	Mainly used for debugging and benchmarking, this aio request puts one of
548	the request workers to sleep for the given time.	731	the request workers to sleep for the given time.
549		732
550	While it is theoretically handy to have simple I/O scheduling requests	733	While it is theoretically handy to have simple I/O scheduling requests
551	like sleep and file handle readable/writable, the overhead this creates	734	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	735	immense (it blocks a thread for a long time) so do not use this function
553	under artificial I/O pressure.	736	except to put your application under artificial I/O pressure.
554		737
555	=back	738	=back
556		739
557	=head2 IO::AIO::REQ CLASS	740	=head2 IO::AIO::REQ CLASS
558		741
559	All non-aggregate C<aio_*> functions return an object of this class when	742	All non-aggregate C<aio_*> functions return an object of this class when
560	called in non-void context.	743	called in non-void context.
561		744
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	745	=over 4
571		746
572	=item $req->cancel	747	=item cancel $req
573		748
574	Cancels the request, if possible. Has the effect of skipping execution	749	Cancels the request, if possible. Has the effect of skipping execution
575	when entering the B<execute> state and skipping calling the callback when	750	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	751	entering the the B<result> state, but will leave the request otherwise
577	untouched. That means that requests that currently execute will not be	752	untouched. That means that requests that currently execute will not be
578	stopped and resources held by the request will not be freed prematurely.	753	stopped and resources held by the request will not be freed prematurely.
579		754
		755	=item cb $req $callback->(...)
		756
		757	Replace (or simply set) the callback registered to the request.
		758
580	=back	759	=back
581		760
582	=head2 IO::AIO::GRP CLASS	761	=head2 IO::AIO::GRP CLASS
583		762
584	This class is a subclass of L<IO::AIO::REQ>, so all its methods apply to	763	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.	802	=item * They can also can also be added to other IO::AIO::GRP objects.
624		803
625	=item * You must not add requests to a group from within the group callback (or	804	=item * You must not add requests to a group from within the group callback (or
626	any later time).	805	any later time).
627		806
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	807	=back
633		808
634	Their lifetime, simplified, looks like this: when they are empty, they	809	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	810	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	811	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	816	group. And only when all those requests have finished will the the group
642	itself finish.	817	itself finish.
643		818
644	=over 4	819	=over 4
645		820
		821	=item add $grp ...
		822
646	=item $grp->add (...)	823	=item $grp->add (...)
647
648	=item add $grp ...
649		824
650	Add one or more requests to the group. Any type of L<IO::AIO::REQ> can	825	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	826	be added, including other groups, as long as you do not create circular
652	dependencies.	827	dependencies.
653		828
654	Returns all its arguments.	829	Returns all its arguments.
655		830
		831	=item $grp->cancel_subs
		832
		833	Cancel all subrequests and clears any feeder, but not the group request
		834	itself. Useful when you queued a lot of events but got a result early.
		835
656	=item $grp->result (...)	836	=item $grp->result (...)
657		837
658	Set the result value(s) that will be passed to the group callback when all	838	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.	839	subrequests have finished and set thre groups errno to the current value
		840	of errno (just like calling C<errno> without an error number). By default,
		841	no argument will be passed and errno is zero.
660		842
661	=item $grp->set_feeder ($callback->($grp))	843	=item $grp->errno ([$errno])
662		844
663	[VERY EXPERIMENTAL]	845	Sets the group errno value to C<$errno>, or the current value of errno
		846	when the argument is missing.
		847
		848	Every aio request has an associated errno value that is restored when
		849	the callback is invoked. This method lets you change this value from its
		850	default (0).
		851
		852	Calling C<result> will also set errno, so make sure you either set C<$!>
		853	before the call to C<result>, or call c<errno> after it.
		854
		855	=item feed $grp $callback->($grp)
664		856
665	Sets a feeder/generator on this group: every group can have an attached	857	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,	858	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,	859	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	860	this might starve other requests for a potentially long time. For
669	example, C<aio_scandir> might generate hundreds of thousands C<aio_stat>	861	example, C<aio_scandir> might generate hundreds of thousands C<aio_stat>
670	requests, delaying any later requests for a long time.	862	requests, delaying any later requests for a long time.
671		863
672	To avoid this, and allow incremental generation of requests, you can	864	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	865	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>,	866	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	867	below) requests active in the group itself and is expected to queue more
676	requests.	868	requests.
677		869
678	The feeder can queue as many requests as it likes (i.e. C<add> does not	870	The feed callback can queue as many requests as it likes (i.e. C<add> does
679	impose any limits).	871	not impose any limits).
680		872
681	If the feeder does not queue more requests when called, it will be	873	If the feed does not queue more requests when called, it will be
682	automatically removed from the group.	874	automatically removed from the group.
683		875
684	If the feeder limit is C<0>, it will be set to C<2> automatically.	876	If the feed limit is C<0>, it will be set to C<2> automatically.
685		877
686	Example:	878	Example:
687		879
688	# stat all files in @files, but only ever use four aio requests concurrently:	880	# stat all files in @files, but only ever use four aio requests concurrently:
689		881
690	my $grp = aio_group sub { print "finished\n" };	882	my $grp = aio_group sub { print "finished\n" };
691	$grp->feeder_limit (4);	883	limit $grp 4;
692	$grp->set_feeder (sub {	884	feed $grp sub {
693	my $file = pop @files	885	my $file = pop @files
694	or return;	886	or return;
695		887
696	add $grp aio_stat $file, sub { ... };	888	add $grp aio_stat $file, sub { ... };
697	});	889	};
698		890
699	=item $grp->feeder_limit ($num)	891	=item limit $grp $num
700		892
701	Sets the feeder limit for the group: The feeder will be called whenever	893	Sets the feeder limit for the group: The feeder will be called whenever
702	the group contains less than this many requests.	894	the group contains less than this many requests.
703		895
704	Setting the limit to C<0> will pause the feeding process.	896	Setting the limit to C<0> will pause the feeding process.
705		897
706	=back	898	=back
707		899
708	=head2 SUPPORT FUNCTIONS	900	=head2 SUPPORT FUNCTIONS
		901
		902	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
709		903
710	=over 4	904	=over 4
711		905
712	=item $fileno = IO::AIO::poll_fileno	906	=item $fileno = IO::AIO::poll_fileno
713		907
…		…
718		912
719	See C<poll_cb> for an example.	913	See C<poll_cb> for an example.
720		914
721	=item IO::AIO::poll_cb	915	=item IO::AIO::poll_cb
722		916
723	Process all outstanding events on the result pipe. You have to call this	917	Process some outstanding events on the result pipe. You have to call this
724	regularly. Returns the number of events processed. Returns immediately	918	regularly. Returns the number of events processed. Returns immediately
725	when no events are outstanding.	919	when no events are outstanding. The amount of events processed depends on
		920	the settings of C<IO::AIO::max_poll_req> and C<IO::AIO::max_poll_time>.
		921
		922	If not all requests were processed for whatever reason, the filehandle
		923	will still be ready when C<poll_cb> returns.
726		924
727	Example: Install an Event watcher that automatically calls	925	Example: Install an Event watcher that automatically calls
728	IO::AIO::poll_cb with high priority:	926	IO::AIO::poll_cb with high priority:
729		927
730	Event->io (fd => IO::AIO::poll_fileno,	928	Event->io (fd => IO::AIO::poll_fileno,
731	poll => 'r', async => 1,	929	poll => 'r', async => 1,
732	cb => \&IO::AIO::poll_cb);	930	cb => \&IO::AIO::poll_cb);
733		931
		932	=item IO::AIO::max_poll_reqs $nreqs
		933
		934	=item IO::AIO::max_poll_time $seconds
		935
		936	These set the maximum number of requests (default C<0>, meaning infinity)
		937	that are being processed by C<IO::AIO::poll_cb> in one call, respectively
		938	the maximum amount of time (default C<0>, meaning infinity) spent in
		939	C<IO::AIO::poll_cb> to process requests (more correctly the mininum amount
		940	of time C<poll_cb> is allowed to use).
		941
		942	Setting these is useful if you want to ensure some level of
		943	interactiveness when perl is not fast enough to process all requests in
		944	time.
		945
		946	For interactive programs, values such as C<0.01> to C<0.1> should be fine.
		947
		948	Example: Install an Event watcher that automatically calls
		949	IO::AIO::poll_some with low priority, to ensure that other parts of the
		950	program get the CPU sometimes even under high AIO load.
		951
		952	# try not to spend much more than 0.1s in poll_cb
		953	IO::AIO::max_poll_time 0.1;
		954
		955	# use a low priority so other tasks have priority
		956	Event->io (fd => IO::AIO::poll_fileno,
		957	poll => 'r', nice => 1,
		958	cb => &IO::AIO::poll_cb);
		959
734	=item IO::AIO::poll_wait	960	=item IO::AIO::poll_wait
735		961
736	Wait till the result filehandle becomes ready for reading (simply does a	962	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	963	C<select> on the filehandle. This is useful if you want to synchronously
738	for some requests to finish).	964	wait for some requests to finish).
739		965
740	See C<nreqs> for an example.	966	See C<nreqs> for an example.
741		967
		968	=item IO::AIO::poll
		969
		970	Waits until some requests have been handled.
		971
		972	Strictly equivalent to:
		973
		974	IO::AIO::poll_wait, IO::AIO::poll_cb
		975	if IO::AIO::nreqs;
		976
742	=item IO::AIO::nreqs	977	=item IO::AIO::flush
743		978
744	Returns the number of requests currently outstanding (i.e. for which their	979	Wait till all outstanding AIO requests have been handled.
745	callback has not been invoked yet).
746		980
747	Example: wait till there are no outstanding requests anymore:	981	Strictly equivalent to:
748		982
749	IO::AIO::poll_wait, IO::AIO::poll_cb	983	IO::AIO::poll_wait, IO::AIO::poll_cb
750	while IO::AIO::nreqs;	984	while IO::AIO::nreqs;
751		985
752	=item IO::AIO::flush	986	=head3 CONTROLLING THE NUMBER OF THREADS
753
754	Wait till all outstanding AIO requests have been handled.
755
756	Strictly equivalent to:
757
758	IO::AIO::poll_wait, IO::AIO::poll_cb
759	while IO::AIO::nreqs;
760
761	=item IO::AIO::poll
762
763	Waits until some requests have been handled.
764
765	Strictly equivalent to:
766
767	IO::AIO::poll_wait, IO::AIO::poll_cb
768	if IO::AIO::nreqs;
769		987
770	=item IO::AIO::min_parallel $nthreads	988	=item IO::AIO::min_parallel $nthreads
771		989
772	Set the minimum number of AIO threads to C<$nthreads>. The current	990	Set the minimum number of AIO threads to C<$nthreads>. The current
773	default is C<8>, which means eight asynchronous operations can execute	991	default is C<8>, which means eight asynchronous operations can execute
774	concurrently at any one time (the number of outstanding requests,	992	concurrently at any one time (the number of outstanding requests,
775	however, is unlimited).	993	however, is unlimited).
776		994
777	IO::AIO starts threads only on demand, when an AIO request is queued and	995	IO::AIO starts threads only on demand, when an AIO request is queued and
778	no free thread exists.	996	no free thread exists. Please note that queueing up a hundred requests can
		997	create demand for a hundred threads, even if it turns out that everything
		998	is in the cache and could have been processed faster by a single thread.
779		999
780	It is recommended to keep the number of threads relatively low, as some	1000	It is recommended to keep the number of threads relatively low, as some
781	Linux kernel versions will scale negatively with the number of threads	1001	Linux kernel versions will scale negatively with the number of threads
782	(higher parallelity => MUCH higher latency). With current Linux 2.6	1002	(higher parallelity => MUCH higher latency). With current Linux 2.6
783	versions, 4-32 threads should be fine.	1003	versions, 4-32 threads should be fine.
…		…
797	This module automatically runs C<max_parallel 0> at program end, to ensure	1017	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.	1018	that all threads are killed and that there are no outstanding requests.
799		1019
800	Under normal circumstances you don't need to call this function.	1020	Under normal circumstances you don't need to call this function.
801		1021
		1022	=item IO::AIO::max_idle $nthreads
		1023
		1024	Limit the number of threads (default: 4) that are allowed to idle (i.e.,
		1025	threads that did not get a request to process within 10 seconds). That
		1026	means if a thread becomes idle while C<$nthreads> other threads are also
		1027	idle, it will free its resources and exit.
		1028
		1029	This is useful when you allow a large number of threads (e.g. 100 or 1000)
		1030	to allow for extremely high load situations, but want to free resources
		1031	under normal circumstances (1000 threads can easily consume 30MB of RAM).
		1032
		1033	The default is probably ok in most situations, especially if thread
		1034	creation is fast. If thread creation is very slow on your system you might
		1035	want to use larger values.
		1036
802	=item $oldnreqs = IO::AIO::max_outstanding $nreqs	1037	=item $oldmaxreqs = IO::AIO::max_outstanding $maxreqs
803		1038
804	[DEPRECATED]	1039	This is a very bad function to use in interactive programs because it
		1040	blocks, and a bad way to reduce concurrency because it is inexact: Better
		1041	use an C<aio_group> together with a feed callback.
805		1042
806	Sets the maximum number of outstanding requests to C<$nreqs>. If you	1043	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	1044	to queue up more than this number of requests, the next call to the
808	some requests have been handled.	1045	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
		1046	function will block until the limit is no longer exceeded.
809		1047
810	The default is very large, so normally there is no practical limit. If you	1048	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	1049	number of outstanding requests.
812	this to a relatively low number, such as C<100>.
813		1050
814	This function does not work well together with C<aio_group>'s, and their	1051	You can still queue as many requests as you want. Therefore,
815	feeder interface is better suited to limiting concurrency, so do not use	1052	C<max_oustsanding> is mainly useful in simple scripts (with low values) or
816	this function.	1053	as a stop gap to shield against fatal memory overflow (with large values).
817		1054
818	Under normal circumstances you don't need to call this function.	1055	=head3 STATISTICAL INFORMATION
		1056
		1057	=item IO::AIO::nreqs
		1058
		1059	Returns the number of requests currently in the ready, execute or pending
		1060	states (i.e. for which their callback has not been invoked yet).
		1061
		1062	Example: wait till there are no outstanding requests anymore:
		1063
		1064	IO::AIO::poll_wait, IO::AIO::poll_cb
		1065	while IO::AIO::nreqs;
		1066
		1067	=item IO::AIO::nready
		1068
		1069	Returns the number of requests currently in the ready state (not yet
		1070	executed).
		1071
		1072	=item IO::AIO::npending
		1073
		1074	Returns the number of requests currently in the pending state (executed,
		1075	but not yet processed by poll_cb).
819		1076
820	=back	1077	=back
821		1078
822	=cut	1079	=cut
823		1080
…		…
838	}	1095	}
839		1096
840	min_parallel 8;	1097	min_parallel 8;
841		1098
842	END {	1099	END {
843	max_parallel 0;	1100	min_parallel 1;
844	}	1101	flush;
		1102	};
845		1103
846	1;	1104	1;
847		1105
848	=head2 FORK BEHAVIOUR	1106	=head2 FORK BEHAVIOUR
849		1107
850	This module should do "the right thing" when the process using it forks:	1108	This module should do "the right thing" when the process using it forks:
851		1109
852	Before the fork, IO::AIO enters a quiescent state where no requests	1110	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	1111	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	1112	the fork the parent simply leaves the quiescent state and continues
855	request/result processing, while the child clears the request/result	1113	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	1114	(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	1115	parent). Threads will be started on demand until the limit set in the
858	parent process has been reached again.	1116	parent process has been reached again.
859		1117
860	In short: the parent will, after a short pause, continue as if fork had	1118	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	1119	not been called, while the child will act as if IO::AIO has not been used
862	yet.	1120	yet.
863		1121
864	=head2 MEMORY USAGE	1122	=head2 MEMORY USAGE
865		1123
		1124	Per-request usage:
		1125
866	Each aio request uses - depending on your architecture - around 128 bytes	1126	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	1127	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	1128	a few hundred bytes), readdir requires a result buffer and so on. Perl
869	also be locked.	1129	scalars and other data passed into aio requests will also be locked and
		1130	will consume memory till the request has entered the done state.
870		1131
871	This is now awfully much, so queuing lots of requests is not usually a	1132	This is now awfully much, so queuing lots of requests is not usually a
872	problem.	1133	problem.
873		1134
874	Each thread needs a stack area which is usually around 16k, sometimes much	1135	Per-thread usage:
875	larger, depending on the OS.	1136
		1137	In the execution phase, some aio requests require more memory for
		1138	temporary buffers, and each thread requires a stack and other data
		1139	structures (usually around 16k-128k, depending on the OS).
		1140
		1141	=head1 KNOWN BUGS
		1142
		1143	Known bugs will be fixed in the next release.
876		1144
877	=head1 SEE ALSO	1145	=head1 SEE ALSO
878		1146
879	L<Coro>, L<Linux::AIO> (obsolete).	1147	L<Coro::AIO>.
880		1148
881	=head1 AUTHOR	1149	=head1 AUTHOR
882		1150
883	Marc Lehmann <schmorp@schmorp.de>	1151	Marc Lehmann <schmorp@schmorp.de>
884	http://home.schmorp.de/	1152	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 1.87 by root, Sun Oct 29 00:52:02 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 1.87 by root, Sun Oct 29 00:52:02 2006 UTC