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

Comparing IO-AIO/AIO.pm (file contents):
Revision 1.51 by root, Sat Jun 24 19:14:04 2006 UTC vs.
Revision 1.94 by root, Wed Nov 8 02:01:02 2006 UTC

…		…
5	=head1 SYNOPSIS	5	=head1 SYNOPSIS
6		6
7	use IO::AIO;	7	use IO::AIO;
8		8
9	aio_open "/etc/passwd", O_RDONLY, 0, sub {	9	aio_open "/etc/passwd", O_RDONLY, 0, sub {
10	my ($fh) = @_;	10	my $fh = shift
		11	or die "/etc/passwd: $!";
11	...	12	...
12	};	13	};
13		14
14	aio_unlink "/tmp/file", sub { };	15	aio_unlink "/tmp/file", sub { };
15		16
16	aio_read $fh, 30000, 1024, $buffer, 0, sub {	17	aio_read $fh, 30000, 1024, $buffer, 0, sub {
17	$_[0] > 0 or die "read error: $!";	18	$_[0] > 0 or die "read error: $!";
18	};	19	};
19		20
20	# AnyEvent	21	# version 2+ has request and group objects
		22	use IO::AIO 2;
		23
		24	aioreq_pri 4; # give next request a very high priority
		25	my $req = aio_unlink "/tmp/file", sub { };
		26	$req->cancel; # cancel request if still in queue
		27
		28	my $grp = aio_group sub { print "all stats done\n" };
		29	add $grp aio_stat "..." for ...;
		30
		31	# AnyEvent integration
21	open my $fh, "<&=" . IO::AIO::poll_fileno or die "$!";	32	open my $fh, "<&=" . IO::AIO::poll_fileno or die "$!";
22	my $w = AnyEvent->io (fh => $fh, poll => 'r', cb => sub { IO::AIO::poll_cb });	33	my $w = AnyEvent->io (fh => $fh, poll => 'r', cb => sub { IO::AIO::poll_cb });
23		34
24	# Event	35	# Event integration
25	Event->io (fd => IO::AIO::poll_fileno,	36	Event->io (fd => IO::AIO::poll_fileno,
26	poll => 'r',	37	poll => 'r',
27	cb => \&IO::AIO::poll_cb);	38	cb => \&IO::AIO::poll_cb);
28		39
29	# Glib/Gtk2	40	# Glib/Gtk2 integration
30	add_watch Glib::IO IO::AIO::poll_fileno,	41	add_watch Glib::IO IO::AIO::poll_fileno,
31	in => sub { IO::AIO::poll_cb; 1 };	42	in => sub { IO::AIO::poll_cb; 1 };
32		43
33	# Tk	44	# Tk integration
34	Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",	45	Tk::Event::IO->fileevent (IO::AIO::poll_fileno, "",
35	readable => \&IO::AIO::poll_cb);	46	readable => \&IO::AIO::poll_cb);
36		47
37	# Danga::Socket	48	# Danga::Socket integration
38	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>	49	Danga::Socket->AddOtherFds (IO::AIO::poll_fileno =>
39	\&IO::AIO::poll_cb);	50	\&IO::AIO::poll_cb);
40		51
41
42	=head1 DESCRIPTION	52	=head1 DESCRIPTION
43		53
44	This module implements asynchronous I/O using whatever means your	54	This module implements asynchronous I/O using whatever means your
45	operating system supports.	55	operating system supports.
46		56
		57	Asynchronous means that operations that can normally block your program
		58	(e.g. reading from disk) will be done asynchronously: the operation
		59	will still block, but you can do something else in the meantime. This
		60	is extremely useful for programs that need to stay interactive even
		61	when doing heavy I/O (GUI programs, high performance network servers
		62	etc.), but can also be used to easily do operations in parallel that are
		63	normally done sequentially, e.g. stat'ing many files, which is much faster
		64	on a RAID volume or over NFS when you do a number of stat operations
		65	concurrently.
		66
		67	While most of this works on all types of file descriptors (for example
		68	sockets), using these functions on file descriptors that support
		69	nonblocking operation (again, sockets, pipes etc.) is very inefficient or
		70	might not work (aio_read fails on sockets/pipes/fifos). Use an event loop
		71	for that (such as the L<Event\|Event> module): IO::AIO will naturally fit
		72	into such an event loop itself.
		73
47	Currently, a number of threads are started that execute your read/writes	74	In this version, a number of threads are started that execute your
48	and signal their completion. You don't need thread support in your libc or	75	requests and signal their completion. You don't need thread support
49	perl, and the threads created by this module will not be visible to the	76	in perl, and the threads created by this module will not be visible
50	pthreads library. In the future, this module might make use of the native	77	to perl. In the future, this module might make use of the native aio
51	aio functions available on many operating systems. However, they are often	78	functions available on many operating systems. However, they are often
52	not well-supported (Linux doesn't allow them on normal files currently,	79	not well-supported or restricted (GNU/Linux doesn't allow them on normal
53	for example), and they would only support aio_read and aio_write, so the	80	files currently, for example), and they would only support aio_read and
54	remaining functionality would have to be implemented using threads anyway.	81	aio_write, so the remaining functionality would have to be implemented
		82	using threads anyway.
55		83
56	Although the module will work with in the presence of other threads, it is	84	Although the module will work with in the presence of other (Perl-)
57	currently not reentrant, so use appropriate locking yourself, always call	85	threads, it is currently not reentrant in any way, so use appropriate
58	C<poll_cb> from within the same thread, or never call C<poll_cb> (or other	86	locking yourself, always call C<poll_cb> from within the same thread, or
59	C<aio_> functions) recursively.	87	never call C<poll_cb> (or other C<aio_> functions) recursively.
		88
		89	=head2 EXAMPLE
		90
		91	This is a simple example that uses the Event module and loads
		92	F</etc/passwd> asynchronously:
		93
		94	use Fcntl;
		95	use Event;
		96	use IO::AIO;
		97
		98	# register the IO::AIO callback with Event
		99	Event->io (fd => IO::AIO::poll_fileno,
		100	poll => 'r',
		101	cb => \&IO::AIO::poll_cb);
		102
		103	# queue the request to open /etc/passwd
		104	aio_open "/etc/passwd", O_RDONLY, 0, sub {
		105	my $fh = shift
		106	or die "error while opening: $!";
		107
		108	# stat'ing filehandles is generally non-blocking
		109	my $size = -s $fh;
		110
		111	# queue a request to read the file
		112	my $contents;
		113	aio_read $fh, 0, $size, $contents, 0, sub {
		114	$_[0] == $size
		115	or die "short read: $!";
		116
		117	close $fh;
		118
		119	# file contents now in $contents
		120	print $contents;
		121
		122	# exit event loop and program
		123	Event::unloop;
		124	};
		125	};
		126
		127	# possibly queue up other requests, or open GUI windows,
		128	# check for sockets etc. etc.
		129
		130	# process events as long as there are some:
		131	Event::loop;
		132
		133	=head1 REQUEST ANATOMY AND LIFETIME
		134
		135	Every C<aio_*> function creates a request. which is a C data structure not
		136	directly visible to Perl.
		137
		138	If called in non-void context, every request function returns a Perl
		139	object representing the request. In void context, nothing is returned,
		140	which saves a bit of memory.
		141
		142	The perl object is a fairly standard ref-to-hash object. The hash contents
		143	are not used by IO::AIO so you are free to store anything you like in it.
		144
		145	During their existance, aio requests travel through the following states,
		146	in order:
		147
		148	=over 4
		149
		150	=item ready
		151
		152	Immediately after a request is created it is put into the ready state,
		153	waiting for a thread to execute it.
		154
		155	=item execute
		156
		157	A thread has accepted the request for processing and is currently
		158	executing it (e.g. blocking in read).
		159
		160	=item pending
		161
		162	The request has been executed and is waiting for result processing.
		163
		164	While request submission and execution is fully asynchronous, result
		165	processing is not and relies on the perl interpreter calling C<poll_cb>
		166	(or another function with the same effect).
		167
		168	=item result
		169
		170	The request results are processed synchronously by C<poll_cb>.
		171
		172	The C<poll_cb> function will process all outstanding aio requests by
		173	calling their callbacks, freeing memory associated with them and managing
		174	any groups they are contained in.
		175
		176	=item done
		177
		178	Request has reached the end of its lifetime and holds no resources anymore
		179	(except possibly for the Perl object, but its connection to the actual
		180	aio request is severed and calling its methods will either do nothing or
		181	result in a runtime error).
		182
		183	=back
60		184
61	=cut	185	=cut
62		186
63	package IO::AIO;	187	package IO::AIO;
64		188
…		…
66	use strict 'vars';	190	use strict 'vars';
67		191
68	use base 'Exporter';	192	use base 'Exporter';
69		193
70	BEGIN {	194	BEGIN {
71	our $VERSION = '1.8';	195	our $VERSION = '2.2';
72		196
73	our @EXPORT = qw(aio_sendfile aio_read aio_write aio_open aio_close aio_stat	197	our @AIO_REQ = qw(aio_sendfile aio_read aio_write aio_open aio_close aio_stat
74	aio_lstat aio_unlink aio_rmdir aio_readdir aio_scandir aio_symlink	198	aio_lstat aio_unlink aio_rmdir aio_readdir aio_scandir aio_symlink
75	aio_fsync aio_fdatasync aio_readahead aio_rename aio_link aio_move);	199	aio_readlink aio_fsync aio_fdatasync aio_readahead aio_rename aio_link
76	our @EXPORT_OK = qw(poll_fileno poll_cb min_parallel max_parallel max_outstanding nreqs);	200	aio_move aio_copy aio_group aio_nop aio_mknod);
		201	our @EXPORT = (@AIO_REQ, qw(aioreq_pri aioreq_nice));
		202	our @EXPORT_OK = qw(poll_fileno poll_cb poll_wait flush
		203	min_parallel max_parallel max_idle
		204	nreqs nready npending nthreads
		205	max_poll_time max_poll_reqs);
		206
		207	@IO::AIO::GRP::ISA = 'IO::AIO::REQ';
77		208
78	require XSLoader;	209	require XSLoader;
79	XSLoader::load ("IO::AIO", $VERSION);	210	XSLoader::load ("IO::AIO", $VERSION);
80	}	211	}
81		212
82	=head1 FUNCTIONS	213	=head1 FUNCTIONS
83		214
84	=head2 AIO FUNCTIONS	215	=head2 AIO REQUEST FUNCTIONS
85		216
86	All the C<aio_*> calls are more or less thin wrappers around the syscall	217	All the C<aio_*> calls are more or less thin wrappers around the syscall
87	with the same name (sans C<aio_>). The arguments are similar or identical,	218	with the same name (sans C<aio_>). The arguments are similar or identical,
88	and they all accept an additional (and optional) C<$callback> argument	219	and they all accept an additional (and optional) C<$callback> argument
89	which must be a code reference. This code reference will get called with	220	which must be a code reference. This code reference will get called with
…		…
92	syscall has been executed asynchronously.	223	syscall has been executed asynchronously.
93		224
94	All functions expecting a filehandle keep a copy of the filehandle	225	All functions expecting a filehandle keep a copy of the filehandle
95	internally until the request has finished.	226	internally until the request has finished.
96		227
		228	All functions return request objects of type L<IO::AIO::REQ> that allow
		229	further manipulation of those requests while they are in-flight.
		230
97	The pathnames you pass to these routines I<must> be absolute and	231	The pathnames you pass to these routines I<must> be absolute and
98	encoded in byte form. The reason for the former is that at the time the	232	encoded as octets. The reason for the former is that at the time the
99	request is being executed, the current working directory could have	233	request is being executed, the current working directory could have
100	changed. Alternatively, you can make sure that you never change the	234	changed. Alternatively, you can make sure that you never change the
101	current working directory.	235	current working directory anywhere in the program and then use relative
		236	paths.
102		237
103	To encode pathnames to byte form, either make sure you either: a)	238	To encode pathnames as octets, either make sure you either: a) always pass
104	always pass in filenames you got from outside (command line, readdir	239	in filenames you got from outside (command line, readdir etc.) without
105	etc.), b) are ASCII or ISO 8859-1, c) use the Encode module and encode	240	tinkering, b) are ASCII or ISO 8859-1, c) use the Encode module and encode
106	your pathnames to the locale (or other) encoding in effect in the user	241	your pathnames to the locale (or other) encoding in effect in the user
107	environment, d) use Glib::filename_from_unicode on unicode filenames or e)	242	environment, d) use Glib::filename_from_unicode on unicode filenames or e)
108	use something else.	243	use something else to ensure your scalar has the correct contents.
		244
		245	This works, btw. independent of the internal UTF-8 bit, which IO::AIO
		246	handles correctly wether it is set or not.
109		247
110	=over 4	248	=over 4
		249
		250	=item $prev_pri = aioreq_pri [$pri]
		251
		252	Returns the priority value that would be used for the next request and, if
		253	C<$pri> is given, sets the priority for the next aio request.
		254
		255	The default priority is C<0>, the minimum and maximum priorities are C<-4>
		256	and C<4>, respectively. Requests with higher priority will be serviced
		257	first.
		258
		259	The priority will be reset to C<0> after each call to one of the C<aio_*>
		260	functions.
		261
		262	Example: open a file with low priority, then read something from it with
		263	higher priority so the read request is serviced before other low priority
		264	open requests (potentially spamming the cache):
		265
		266	aioreq_pri -3;
		267	aio_open ..., sub {
		268	return unless $_[0];
		269
		270	aioreq_pri -2;
		271	aio_read $_[0], ..., sub {
		272	...
		273	};
		274	};
		275
		276	=item aioreq_nice $pri_adjust
		277
		278	Similar to C<aioreq_pri>, but subtracts the given value from the current
		279	priority, so the effect is cumulative.
111		280
112	=item aio_open $pathname, $flags, $mode, $callback->($fh)	281	=item aio_open $pathname, $flags, $mode, $callback->($fh)
113		282
114	Asynchronously open or create a file and call the callback with a newly	283	Asynchronously open or create a file and call the callback with a newly
115	created filehandle for the file.	284	created filehandle for the file.
…		…
165		334
166	aio_read $fh, 7, 15, $buffer, 0, sub {	335	aio_read $fh, 7, 15, $buffer, 0, sub {
167	$_[0] > 0 or die "read error: $!";	336	$_[0] > 0 or die "read error: $!";
168	print "read $_[0] bytes: <$buffer>\n";	337	print "read $_[0] bytes: <$buffer>\n";
169	};	338	};
170
171	=item aio_move $srcpath, $dstpath, $callback->($status)
172
173	[EXPERIMENTAL]
174
175	Try to move the I<file> (directories not supported as either source or destination)
176	from C<$srcpath> to C<$dstpath> and call the callback with the C<0> (error) or C<-1> ok.
177
178	This is a composite request that tries to rename(2) the file first. If
179	rename files with C<EXDEV>, it creates the destination file with mode 0200
180	and copies the contents of the source file into it using C<aio_sendfile>,
181	followed by restoring atime, mtime, access mode and uid/gid, in that
182	order, and unlinking the C<$srcpath>.
183
184	If an error occurs, the partial destination file will be unlinked, if
185	possible, except when setting atime, mtime, access mode and uid/gid, where
186	errors are being ignored.
187
188	=cut
189
190	sub aio_move($$$) {
191	my ($src, $dst, $cb) = @_;
192
193	aio_rename $src, $dst, sub {
194	if ($_[0] && $! == EXDEV) {
195	aio_open $src, O_RDONLY, 0, sub {
196	if (my $src_fh = $_[0]) {
197	my @stat = stat $src_fh;
198
199	aio_open $dst, O_WRONLY, 0200, sub {
200	if (my $dst_fh = $_[0]) {
201	aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
202	close $src_fh;
203
204	if ($_[0] == $stat[7]) {
205	utime $stat[8], $stat[9], $dst;
206	chmod $stat[2] & 07777, $dst_fh;
207	chown $stat[4], $stat[5], $dst_fh;
208	close $dst_fh;
209
210	aio_unlink $src, sub {
211	$cb->($_[0]);
212	};
213	} else {
214	my $errno = $!;
215	aio_unlink $dst, sub {
216	$! = $errno;
217	$cb->(-1);
218	};
219	}
220	};
221	} else {
222	$cb->(-1);
223	}
224	},
225
226	} else {
227	$cb->(-1);
228	}
229	};
230	} else {
231	$cb->($_[0]);
232	}
233	};
234	}
235		339
236	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)	340	=item aio_sendfile $out_fh, $in_fh, $in_offset, $length, $callback->($retval)
237		341
238	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts	342	Tries to copy C<$length> bytes from C<$in_fh> to C<$out_fh>. It starts
239	reading at byte offset C<$in_offset>, and starts writing at the current	343	reading at byte offset C<$in_offset>, and starts writing at the current
…		…
295	=item aio_unlink $pathname, $callback->($status)	399	=item aio_unlink $pathname, $callback->($status)
296		400
297	Asynchronously unlink (delete) a file and call the callback with the	401	Asynchronously unlink (delete) a file and call the callback with the
298	result code.	402	result code.
299		403
		404	=item aio_mknod $path, $mode, $dev, $callback->($status)
		405
		406	[EXPERIMENTAL]
		407
		408	Asynchronously create a device node (or fifo). See mknod(2).
		409
		410	The only (POSIX-) portable way of calling this function is:
		411
		412	aio_mknod $path, IO::AIO::S_IFIFO \| $mode, 0, sub { ...
		413
300	=item aio_link $srcpath, $dstpath, $callback->($status)	414	=item aio_link $srcpath, $dstpath, $callback->($status)
301		415
302	Asynchronously create a new link to the existing object at C<$srcpath> at	416	Asynchronously create a new link to the existing object at C<$srcpath> at
303	the path C<$dstpath> and call the callback with the result code.	417	the path C<$dstpath> and call the callback with the result code.
304		418
305	=item aio_symlink $srcpath, $dstpath, $callback->($status)	419	=item aio_symlink $srcpath, $dstpath, $callback->($status)
306		420
307	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at	421	Asynchronously create a new symbolic link to the existing object at C<$srcpath> at
308	the path C<$dstpath> and call the callback with the result code.	422	the path C<$dstpath> and call the callback with the result code.
		423
		424	=item aio_readlink $path, $callback->($link)
		425
		426	Asynchronously read the symlink specified by C<$path> and pass it to
		427	the callback. If an error occurs, nothing or undef gets passed to the
		428	callback.
309		429
310	=item aio_rename $srcpath, $dstpath, $callback->($status)	430	=item aio_rename $srcpath, $dstpath, $callback->($status)
311		431
312	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as	432	Asynchronously rename the object at C<$srcpath> to C<$dstpath>, just as
313	rename(2) and call the callback with the result code.	433	rename(2) and call the callback with the result code.
…		…
324	sorted, and will B<NOT> include the C<.> and C<..> entries.	444	sorted, and will B<NOT> include the C<.> and C<..> entries.
325		445
326	The callback a single argument which is either C<undef> or an array-ref	446	The callback a single argument which is either C<undef> or an array-ref
327	with the filenames.	447	with the filenames.
328		448
		449	=item aio_copy $srcpath, $dstpath, $callback->($status)
		450
		451	Try to copy the I<file> (directories not supported as either source or
		452	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		453	the C<0> (error) or C<-1> ok.
		454
		455	This is a composite request that it creates the destination file with
		456	mode 0200 and copies the contents of the source file into it using
		457	C<aio_sendfile>, followed by restoring atime, mtime, access mode and
		458	uid/gid, in that order.
		459
		460	If an error occurs, the partial destination file will be unlinked, if
		461	possible, except when setting atime, mtime, access mode and uid/gid, where
		462	errors are being ignored.
		463
		464	=cut
		465
		466	sub aio_copy($$;$) {
		467	my ($src, $dst, $cb) = @_;
		468
		469	my $pri = aioreq_pri;
		470	my $grp = aio_group $cb;
		471
		472	aioreq_pri $pri;
		473	add $grp aio_open $src, O_RDONLY, 0, sub {
		474	if (my $src_fh = $_[0]) {
		475	my @stat = stat $src_fh;
		476
		477	aioreq_pri $pri;
		478	add $grp aio_open $dst, O_CREAT \| O_WRONLY \| O_TRUNC, 0200, sub {
		479	if (my $dst_fh = $_[0]) {
		480	aioreq_pri $pri;
		481	add $grp aio_sendfile $dst_fh, $src_fh, 0, $stat[7], sub {
		482	if ($_[0] == $stat[7]) {
		483	$grp->result (0);
		484	close $src_fh;
		485
		486	# those should not normally block. should. should.
		487	utime $stat[8], $stat[9], $dst;
		488	chmod $stat[2] & 07777, $dst_fh;
		489	chown $stat[4], $stat[5], $dst_fh;
		490	close $dst_fh;
		491	} else {
		492	$grp->result (-1);
		493	close $src_fh;
		494	close $dst_fh;
		495
		496	aioreq $pri;
		497	add $grp aio_unlink $dst;
		498	}
		499	};
		500	} else {
		501	$grp->result (-1);
		502	}
		503	},
		504
		505	} else {
		506	$grp->result (-1);
		507	}
		508	};
		509
		510	$grp
		511	}
		512
		513	=item aio_move $srcpath, $dstpath, $callback->($status)
		514
		515	Try to move the I<file> (directories not supported as either source or
		516	destination) from C<$srcpath> to C<$dstpath> and call the callback with
		517	the C<0> (error) or C<-1> ok.
		518
		519	This is a composite request that tries to rename(2) the file first. If
		520	rename files with C<EXDEV>, it copies the file with C<aio_copy> and, if
		521	that is successful, unlinking the C<$srcpath>.
		522
		523	=cut
		524
		525	sub aio_move($$;$) {
		526	my ($src, $dst, $cb) = @_;
		527
		528	my $pri = aioreq_pri;
		529	my $grp = aio_group $cb;
		530
		531	aioreq_pri $pri;
		532	add $grp aio_rename $src, $dst, sub {
		533	if ($_[0] && $! == EXDEV) {
		534	aioreq_pri $pri;
		535	add $grp aio_copy $src, $dst, sub {
		536	$grp->result ($_[0]);
		537
		538	if (!$_[0]) {
		539	aioreq_pri $pri;
		540	add $grp aio_unlink $src;
		541	}
		542	};
		543	} else {
		544	$grp->result ($_[0]);
		545	}
		546	};
		547
		548	$grp
		549	}
		550
329	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)	551	=item aio_scandir $path, $maxreq, $callback->($dirs, $nondirs)
330		552
331	Scans a directory (similar to C<aio_readdir>) and tries to separate the	553	Scans a directory (similar to C<aio_readdir>) but additionally tries to
332	entries of directory C<$path> into two sets of names, ones you can recurse	554	efficiently separate the entries of directory C<$path> into two sets of
333	into (directories), and ones you cannot recurse into (everything else).	555	names, directories you can recurse into (directories), and ones you cannot
		556	recurse into (everything else, including symlinks to directories).
334		557
335	C<aio_scandir> is a composite request that consists of many	558	C<aio_scandir> is a composite request that creates of many sub requests_
336	aio-primitives. C<$maxreq> specifies the maximum number of outstanding	559	C<$maxreq> specifies the maximum number of outstanding aio requests that
337	aio requests that this function generates. If it is C<< <= 0 >>, then a	560	this function generates. If it is C<< <= 0 >>, then a suitable default
338	suitable default will be chosen (currently 8).	561	will be chosen (currently 4).
339		562
340	On error, the callback is called without arguments, otherwise it receives	563	On error, the callback is called without arguments, otherwise it receives
341	two array-refs with path-relative entry names.	564	two array-refs with path-relative entry names.
342		565
343	Example:	566	Example:
…		…
351	Implementation notes.	574	Implementation notes.
352		575
353	The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can.	576	The C<aio_readdir> cannot be avoided, but C<stat()>'ing every entry can.
354		577
355	After reading the directory, the modification time, size etc. of the	578	After reading the directory, the modification time, size etc. of the
356	directory before and after the readdir is checked, and if they match, the	579	directory before and after the readdir is checked, and if they match (and
357	link count will be used to decide how many entries are directories (if	580	isn't the current time), the link count will be used to decide how many
358	>= 2). Otherwise, no knowledge of the number of subdirectories will be	581	entries are directories (if >= 2). Otherwise, no knowledge of the number
359	assumed.	582	of subdirectories will be assumed.
360		583
361	Then entires will be sorted into likely directories (everything without a	584	Then entries will be sorted into likely directories (everything without
362	non-initial dot) and likely non-directories (everything else). Then every	585	a non-initial dot currently) and likely non-directories (everything
363	entry + C</.> will be C<stat>'ed, likely directories first. This is often	586	else). Then every entry plus an appended C</.> will be C<stat>'ed,
		587	likely directories first. If that succeeds, it assumes that the entry
		588	is a directory or a symlink to directory (which will be checked
		589	seperately). This is often faster than stat'ing the entry itself because
364	faster because filesystems might detect the type of the entry without	590	filesystems might detect the type of the entry without reading the inode
365	reading the inode data (e.g. ext2fs filetype feature). If that succeeds,	591	data (e.g. ext2fs filetype feature).
366	it assumes that the entry is a directory or a symlink to directory (which
367	will be checked seperately).
368		592
369	If the known number of directories has been reached, the rest of the	593	If the known number of directories (link count - 2) has been reached, the
370	entries is assumed to be non-directories.	594	rest of the entries is assumed to be non-directories.
		595
		596	This only works with certainty on POSIX (= UNIX) filesystems, which
		597	fortunately are the vast majority of filesystems around.
		598
		599	It will also likely work on non-POSIX filesystems with reduced efficiency
		600	as those tend to return 0 or 1 as link counts, which disables the
		601	directory counting heuristic.
371		602
372	=cut	603	=cut
373		604
374	sub aio_scandir($$$) {	605	sub aio_scandir($$$) {
375	my ($path, $maxreq, $cb) = @_;	606	my ($path, $maxreq, $cb) = @_;
376		607
		608	my $pri = aioreq_pri;
		609
		610	my $grp = aio_group $cb;
		611
377	$maxreq = 8 if $maxreq <= 0;	612	$maxreq = 4 if $maxreq <= 0;
378		613
379	# stat once	614	# stat once
		615	aioreq_pri $pri;
380	aio_stat $path, sub {	616	add $grp aio_stat $path, sub {
381	return $cb->() if $_[0];	617	return $grp->result () if $_[0];
		618	my $now = time;
382	my $hash1 = join ":", (stat _)[0,1,3,7,9];	619	my $hash1 = join ":", (stat _)[0,1,3,7,9];
383		620
384	# read the directory entries	621	# read the directory entries
		622	aioreq_pri $pri;
385	aio_readdir $path, sub {	623	add $grp aio_readdir $path, sub {
386	my $entries = shift	624	my $entries = shift
387	or return $cb->();	625	or return $grp->result ();
388		626
389	# stat the dir another time	627	# stat the dir another time
		628	aioreq_pri $pri;
390	aio_stat $path, sub {	629	add $grp aio_stat $path, sub {
391	my $hash2 = join ":", (stat _)[0,1,3,7,9];	630	my $hash2 = join ":", (stat _)[0,1,3,7,9];
392		631
393	my $ndirs;	632	my $ndirs;
394		633
395	# take the slow route if anything looks fishy	634	# take the slow route if anything looks fishy
396	if ($hash1 ne $hash2) {	635	if ($hash1 ne $hash2 or (stat _)[9] == $now) {
397	$ndirs = -1;	636	$ndirs = -1;
398	} else {	637	} else {
399	# if nlink == 2, we are finished	638	# if nlink == 2, we are finished
400	# on non-posix-fs's, we rely on nlink < 2	639	# on non-posix-fs's, we rely on nlink < 2
401	$ndirs = (stat _)[3] - 2	640	$ndirs = (stat _)[3] - 2
402	or return $cb->([], $entries);	641	or return $grp->result ([], $entries);
403	}	642	}
404		643
405	# sort into likely dirs and likely nondirs	644	# sort into likely dirs and likely nondirs
406	# dirs == files without ".", short entries first	645	# dirs == files without ".", short entries first
407	$entries = [map $_->[0],	646	$entries = [map $_->[0],
…		…
409	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],	648	map [$_, sprintf "%s%04d", (/.\./ ? "1" : "0"), length],
410	@$entries];	649	@$entries];
411		650
412	my (@dirs, @nondirs);	651	my (@dirs, @nondirs);
413		652
414	my ($statcb, $schedcb);	653	my $statgrp = add $grp aio_group sub {
415	my $nreq = 0;	654	$grp->result (\@dirs, \@nondirs);
		655	};
416		656
417	$schedcb = sub {	657	limit $statgrp $maxreq;
418	if (@$entries) {	658	feed $statgrp sub {
419	if ($nreq < $maxreq) {	659	return unless @$entries;
420	my $ent = pop @$entries;	660	my $entry = pop @$entries;
		661
		662	aioreq_pri $pri;
		663	add $statgrp aio_stat "$path/$entry/.", sub {
		664	if ($_[0] < 0) {
		665	push @nondirs, $entry;
		666	} else {
		667	# need to check for real directory
		668	aioreq_pri $pri;
		669	add $statgrp aio_lstat "$path/$entry", sub {
		670	if (-d _) {
		671	push @dirs, $entry;
		672
		673	unless (--$ndirs) {
		674	push @nondirs, @$entries;
		675	feed $statgrp;
		676	}
		677	} else {
		678	push @nondirs, $entry;
		679	}
421	$nreq++;	680	}
422	aio_stat "$path/$ent/.", sub { $statcb->($_[0], $ent) };
423	}	681	}
424	} elsif (!$nreq) {
425	# finished
426	undef $statcb;
427	undef $schedcb;
428	$cb->(\@dirs, \@nondirs) if $cb;
429	undef $cb;
430	}	682	};
431	};	683	};
432	$statcb = sub {
433	my ($status, $entry) = @_;
434
435	if ($status < 0) {
436	$nreq--;
437	push @nondirs, $entry;
438	&$schedcb;
439	} else {
440	# need to check for real directory
441	aio_lstat "$path/$entry", sub {
442	$nreq--;
443
444	if (-d _) {
445	push @dirs, $entry;
446
447	if (!--$ndirs) {
448	push @nondirs, @$entries;
449	$entries = [];
450	}
451	} else {
452	push @nondirs, $entry;
453	}
454
455	&$schedcb;
456	}
457	}
458	};
459
460	&$schedcb while @$entries && $nreq < $maxreq;
461	};	684	};
462	};	685	};
463	};	686	};
		687
		688	$grp
464	}	689	}
465		690
466	=item aio_fsync $fh, $callback->($status)	691	=item aio_fsync $fh, $callback->($status)
467		692
468	Asynchronously call fsync on the given filehandle and call the callback	693	Asynchronously call fsync on the given filehandle and call the callback
…		…
474	callback with the fdatasync result code.	699	callback with the fdatasync result code.
475		700
476	If this call isn't available because your OS lacks it or it couldn't be	701	If this call isn't available because your OS lacks it or it couldn't be
477	detected, it will be emulated by calling C<fsync> instead.	702	detected, it will be emulated by calling C<fsync> instead.
478		703
		704	=item aio_group $callback->(...)
		705
		706	This is a very special aio request: Instead of doing something, it is a
		707	container for other aio requests, which is useful if you want to bundle
		708	many requests into a single, composite, request with a definite callback
		709	and the ability to cancel the whole request with its subrequests.
		710
		711	Returns an object of class L<IO::AIO::GRP>. See its documentation below
		712	for more info.
		713
		714	Example:
		715
		716	my $grp = aio_group sub {
		717	print "all stats done\n";
		718	};
		719
		720	add $grp
		721	(aio_stat ...),
		722	(aio_stat ...),
		723	...;
		724
		725	=item aio_nop $callback->()
		726
		727	This is a special request - it does nothing in itself and is only used for
		728	side effects, such as when you want to add a dummy request to a group so
		729	that finishing the requests in the group depends on executing the given
		730	code.
		731
		732	While this request does nothing, it still goes through the execution
		733	phase and still requires a worker thread. Thus, the callback will not
		734	be executed immediately but only after other requests in the queue have
		735	entered their execution phase. This can be used to measure request
		736	latency.
		737
		738	=item IO::AIO::aio_busy $fractional_seconds, $callback->() NOT EXPORTED
		739
		740	Mainly used for debugging and benchmarking, this aio request puts one of
		741	the request workers to sleep for the given time.
		742
		743	While it is theoretically handy to have simple I/O scheduling requests
		744	like sleep and file handle readable/writable, the overhead this creates is
		745	immense (it blocks a thread for a long time) so do not use this function
		746	except to put your application under artificial I/O pressure.
		747
479	=back	748	=back
480		749
		750	=head2 IO::AIO::REQ CLASS
		751
		752	All non-aggregate C<aio_*> functions return an object of this class when
		753	called in non-void context.
		754
		755	=over 4
		756
		757	=item cancel $req
		758
		759	Cancels the request, if possible. Has the effect of skipping execution
		760	when entering the B<execute> state and skipping calling the callback when
		761	entering the the B<result> state, but will leave the request otherwise
		762	untouched. That means that requests that currently execute will not be
		763	stopped and resources held by the request will not be freed prematurely.
		764
		765	=item cb $req $callback->(...)
		766
		767	Replace (or simply set) the callback registered to the request.
		768
		769	=back
		770
		771	=head2 IO::AIO::GRP CLASS
		772
		773	This class is a subclass of L<IO::AIO::REQ>, so all its methods apply to
		774	objects of this class, too.
		775
		776	A IO::AIO::GRP object is a special request that can contain multiple other
		777	aio requests.
		778
		779	You create one by calling the C<aio_group> constructing function with a
		780	callback that will be called when all contained requests have entered the
		781	C<done> state:
		782
		783	my $grp = aio_group sub {
		784	print "all requests are done\n";
		785	};
		786
		787	You add requests by calling the C<add> method with one or more
		788	C<IO::AIO::REQ> objects:
		789
		790	$grp->add (aio_unlink "...");
		791
		792	add $grp aio_stat "...", sub {
		793	$_[0] or return $grp->result ("error");
		794
		795	# add another request dynamically, if first succeeded
		796	add $grp aio_open "...", sub {
		797	$grp->result ("ok");
		798	};
		799	};
		800
		801	This makes it very easy to create composite requests (see the source of
		802	C<aio_move> for an application) that work and feel like simple requests.
		803
		804	=over 4
		805
		806	=item * The IO::AIO::GRP objects will be cleaned up during calls to
		807	C<IO::AIO::poll_cb>, just like any other request.
		808
		809	=item * They can be canceled like any other request. Canceling will cancel not
		810	only the request itself, but also all requests it contains.
		811
		812	=item * They can also can also be added to other IO::AIO::GRP objects.
		813
		814	=item * You must not add requests to a group from within the group callback (or
		815	any later time).
		816
		817	=back
		818
		819	Their lifetime, simplified, looks like this: when they are empty, they
		820	will finish very quickly. If they contain only requests that are in the
		821	C<done> state, they will also finish. Otherwise they will continue to
		822	exist.
		823
		824	That means after creating a group you have some time to add requests. And
		825	in the callbacks of those requests, you can add further requests to the
		826	group. And only when all those requests have finished will the the group
		827	itself finish.
		828
		829	=over 4
		830
		831	=item add $grp ...
		832
		833	=item $grp->add (...)
		834
		835	Add one or more requests to the group. Any type of L<IO::AIO::REQ> can
		836	be added, including other groups, as long as you do not create circular
		837	dependencies.
		838
		839	Returns all its arguments.
		840
		841	=item $grp->cancel_subs
		842
		843	Cancel all subrequests and clears any feeder, but not the group request
		844	itself. Useful when you queued a lot of events but got a result early.
		845
		846	=item $grp->result (...)
		847
		848	Set the result value(s) that will be passed to the group callback when all
		849	subrequests have finished and set thre groups errno to the current value
		850	of errno (just like calling C<errno> without an error number). By default,
		851	no argument will be passed and errno is zero.
		852
		853	=item $grp->errno ([$errno])
		854
		855	Sets the group errno value to C<$errno>, or the current value of errno
		856	when the argument is missing.
		857
		858	Every aio request has an associated errno value that is restored when
		859	the callback is invoked. This method lets you change this value from its
		860	default (0).
		861
		862	Calling C<result> will also set errno, so make sure you either set C<$!>
		863	before the call to C<result>, or call c<errno> after it.
		864
		865	=item feed $grp $callback->($grp)
		866
		867	Sets a feeder/generator on this group: every group can have an attached
		868	generator that generates requests if idle. The idea behind this is that,
		869	although you could just queue as many requests as you want in a group,
		870	this might starve other requests for a potentially long time. For
		871	example, C<aio_scandir> might generate hundreds of thousands C<aio_stat>
		872	requests, delaying any later requests for a long time.
		873
		874	To avoid this, and allow incremental generation of requests, you can
		875	instead a group and set a feeder on it that generates those requests. The
		876	feed callback will be called whenever there are few enough (see C<limit>,
		877	below) requests active in the group itself and is expected to queue more
		878	requests.
		879
		880	The feed callback can queue as many requests as it likes (i.e. C<add> does
		881	not impose any limits).
		882
		883	If the feed does not queue more requests when called, it will be
		884	automatically removed from the group.
		885
		886	If the feed limit is C<0>, it will be set to C<2> automatically.
		887
		888	Example:
		889
		890	# stat all files in @files, but only ever use four aio requests concurrently:
		891
		892	my $grp = aio_group sub { print "finished\n" };
		893	limit $grp 4;
		894	feed $grp sub {
		895	my $file = pop @files
		896	or return;
		897
		898	add $grp aio_stat $file, sub { ... };
		899	};
		900
		901	=item limit $grp $num
		902
		903	Sets the feeder limit for the group: The feeder will be called whenever
		904	the group contains less than this many requests.
		905
		906	Setting the limit to C<0> will pause the feeding process.
		907
		908	=back
		909
481	=head2 SUPPORT FUNCTIONS	910	=head2 SUPPORT FUNCTIONS
		911
		912	=head3 EVENT PROCESSING AND EVENT LOOP INTEGRATION
482		913
483	=over 4	914	=over 4
484		915
485	=item $fileno = IO::AIO::poll_fileno	916	=item $fileno = IO::AIO::poll_fileno
486		917
…		…
491		922
492	See C<poll_cb> for an example.	923	See C<poll_cb> for an example.
493		924
494	=item IO::AIO::poll_cb	925	=item IO::AIO::poll_cb
495		926
496	Process all outstanding events on the result pipe. You have to call this	927	Process some outstanding events on the result pipe. You have to call this
497	regularly. Returns the number of events processed. Returns immediately	928	regularly. Returns the number of events processed. Returns immediately
498	when no events are outstanding.	929	when no events are outstanding. The amount of events processed depends on
		930	the settings of C<IO::AIO::max_poll_req> and C<IO::AIO::max_poll_time>.
		931
		932	If not all requests were processed for whatever reason, the filehandle
		933	will still be ready when C<poll_cb> returns.
499		934
500	Example: Install an Event watcher that automatically calls	935	Example: Install an Event watcher that automatically calls
501	IO::AIO::poll_cb with high priority:	936	IO::AIO::poll_cb with high priority:
502		937
503	Event->io (fd => IO::AIO::poll_fileno,	938	Event->io (fd => IO::AIO::poll_fileno,
504	poll => 'r', async => 1,	939	poll => 'r', async => 1,
505	cb => \&IO::AIO::poll_cb);	940	cb => \&IO::AIO::poll_cb);
506		941
		942	=item IO::AIO::max_poll_reqs $nreqs
		943
		944	=item IO::AIO::max_poll_time $seconds
		945
		946	These set the maximum number of requests (default C<0>, meaning infinity)
		947	that are being processed by C<IO::AIO::poll_cb> in one call, respectively
		948	the maximum amount of time (default C<0>, meaning infinity) spent in
		949	C<IO::AIO::poll_cb> to process requests (more correctly the mininum amount
		950	of time C<poll_cb> is allowed to use).
		951
		952	Setting C<max_poll_time> to a non-zero value creates an overhead of one
		953	syscall per request processed, which is not normally a problem unless your
		954	callbacks are really really fast or your OS is really really slow (I am
		955	not mentioning Solaris here). Using C<max_poll_reqs> incurs no overhead.
		956
		957	Setting these is useful if you want to ensure some level of
		958	interactiveness when perl is not fast enough to process all requests in
		959	time.
		960
		961	For interactive programs, values such as C<0.01> to C<0.1> should be fine.
		962
		963	Example: Install an Event watcher that automatically calls
		964	IO::AIO::poll_cb with low priority, to ensure that other parts of the
		965	program get the CPU sometimes even under high AIO load.
		966
		967	# try not to spend much more than 0.1s in poll_cb
		968	IO::AIO::max_poll_time 0.1;
		969
		970	# use a low priority so other tasks have priority
		971	Event->io (fd => IO::AIO::poll_fileno,
		972	poll => 'r', nice => 1,
		973	cb => &IO::AIO::poll_cb);
		974
507	=item IO::AIO::poll_wait	975	=item IO::AIO::poll_wait
508		976
		977	If there are any outstanding requests and none of them in the result
509	Wait till the result filehandle becomes ready for reading (simply does a	978	phase, wait till the result filehandle becomes ready for reading (simply
510	C<select> on the filehandle. This is useful if you want to synchronously wait	979	does a C<select> on the filehandle. This is useful if you want to
511	for some requests to finish).	980	synchronously wait for some requests to finish).
512		981
513	See C<nreqs> for an example.	982	See C<nreqs> for an example.
514		983
		984	=item IO::AIO::poll
		985
		986	Waits until some requests have been handled.
		987
		988	Returns the number of requests processed, but is otherwise strictly
		989	equivalent to:
		990
		991	IO::AIO::poll_wait, IO::AIO::poll_cb
		992
515	=item IO::AIO::nreqs	993	=item IO::AIO::flush
516		994
517	Returns the number of requests currently outstanding (i.e. for which their	995	Wait till all outstanding AIO requests have been handled.
518	callback has not been invoked yet).
519		996
520	Example: wait till there are no outstanding requests anymore:	997	Strictly equivalent to:
521		998
522	IO::AIO::poll_wait, IO::AIO::poll_cb	999	IO::AIO::poll_wait, IO::AIO::poll_cb
523	while IO::AIO::nreqs;	1000	while IO::AIO::nreqs;
524		1001
525	=item IO::AIO::flush	1002	=head3 CONTROLLING THE NUMBER OF THREADS
526
527	Wait till all outstanding AIO requests have been handled.
528
529	Strictly equivalent to:
530
531	IO::AIO::poll_wait, IO::AIO::poll_cb
532	while IO::AIO::nreqs;
533
534	=item IO::AIO::poll
535
536	Waits until some requests have been handled.
537
538	Strictly equivalent to:
539
540	IO::AIO::poll_wait, IO::AIO::poll_cb
541	if IO::AIO::nreqs;
542		1003
543	=item IO::AIO::min_parallel $nthreads	1004	=item IO::AIO::min_parallel $nthreads
544		1005
545	Set the minimum number of AIO threads to C<$nthreads>. The current default	1006	Set the minimum number of AIO threads to C<$nthreads>. The current
546	is C<4>, which means four asynchronous operations can be done at one time	1007	default is C<8>, which means eight asynchronous operations can execute
547	(the number of outstanding operations, however, is unlimited).	1008	concurrently at any one time (the number of outstanding requests,
		1009	however, is unlimited).
548		1010
549	IO::AIO starts threads only on demand, when an AIO request is queued and	1011	IO::AIO starts threads only on demand, when an AIO request is queued and
550	no free thread exists.	1012	no free thread exists. Please note that queueing up a hundred requests can
		1013	create demand for a hundred threads, even if it turns out that everything
		1014	is in the cache and could have been processed faster by a single thread.
551		1015
552	It is recommended to keep the number of threads low, as some Linux	1016	It is recommended to keep the number of threads relatively low, as some
553	kernel versions will scale negatively with the number of threads (higher	1017	Linux kernel versions will scale negatively with the number of threads
554	parallelity => MUCH higher latency). With current Linux 2.6 versions, 4-32	1018	(higher parallelity => MUCH higher latency). With current Linux 2.6
555	threads should be fine.	1019	versions, 4-32 threads should be fine.
556		1020
557	Under most circumstances you don't need to call this function, as the	1021	Under most circumstances you don't need to call this function, as the
558	module selects a default that is suitable for low to moderate load.	1022	module selects a default that is suitable for low to moderate load.
559		1023
560	=item IO::AIO::max_parallel $nthreads	1024	=item IO::AIO::max_parallel $nthreads
…		…
569	This module automatically runs C<max_parallel 0> at program end, to ensure	1033	This module automatically runs C<max_parallel 0> at program end, to ensure
570	that all threads are killed and that there are no outstanding requests.	1034	that all threads are killed and that there are no outstanding requests.
571		1035
572	Under normal circumstances you don't need to call this function.	1036	Under normal circumstances you don't need to call this function.
573		1037
		1038	=item IO::AIO::max_idle $nthreads
		1039
		1040	Limit the number of threads (default: 4) that are allowed to idle (i.e.,
		1041	threads that did not get a request to process within 10 seconds). That
		1042	means if a thread becomes idle while C<$nthreads> other threads are also
		1043	idle, it will free its resources and exit.
		1044
		1045	This is useful when you allow a large number of threads (e.g. 100 or 1000)
		1046	to allow for extremely high load situations, but want to free resources
		1047	under normal circumstances (1000 threads can easily consume 30MB of RAM).
		1048
		1049	The default is probably ok in most situations, especially if thread
		1050	creation is fast. If thread creation is very slow on your system you might
		1051	want to use larger values.
		1052
574	=item $oldnreqs = IO::AIO::max_outstanding $nreqs	1053	=item $oldmaxreqs = IO::AIO::max_outstanding $maxreqs
		1054
		1055	This is a very bad function to use in interactive programs because it
		1056	blocks, and a bad way to reduce concurrency because it is inexact: Better
		1057	use an C<aio_group> together with a feed callback.
575		1058
576	Sets the maximum number of outstanding requests to C<$nreqs>. If you	1059	Sets the maximum number of outstanding requests to C<$nreqs>. If you
577	try to queue up more than this number of requests, the caller will block until	1060	to queue up more than this number of requests, the next call to the
578	some requests have been handled.	1061	C<poll_cb> (and C<poll_some> and other functions calling C<poll_cb>)
		1062	function will block until the limit is no longer exceeded.
579		1063
580	The default is very large, so normally there is no practical limit. If you	1064	The default value is very large, so there is no practical limit on the
581	queue up many requests in a loop it often improves speed if you set	1065	number of outstanding requests.
582	this to a relatively low number, such as C<100>.
583		1066
584	Under normal circumstances you don't need to call this function.	1067	You can still queue as many requests as you want. Therefore,
		1068	C<max_oustsanding> is mainly useful in simple scripts (with low values) or
		1069	as a stop gap to shield against fatal memory overflow (with large values).
		1070
		1071	=head3 STATISTICAL INFORMATION
		1072
		1073	=item IO::AIO::nreqs
		1074
		1075	Returns the number of requests currently in the ready, execute or pending
		1076	states (i.e. for which their callback has not been invoked yet).
		1077
		1078	Example: wait till there are no outstanding requests anymore:
		1079
		1080	IO::AIO::poll_wait, IO::AIO::poll_cb
		1081	while IO::AIO::nreqs;
		1082
		1083	=item IO::AIO::nready
		1084
		1085	Returns the number of requests currently in the ready state (not yet
		1086	executed).
		1087
		1088	=item IO::AIO::npending
		1089
		1090	Returns the number of requests currently in the pending state (executed,
		1091	but not yet processed by poll_cb).
585		1092
586	=back	1093	=back
587		1094
588	=cut	1095	=cut
589		1096
…		…
601	or return undef;	1108	or return undef;
602		1109
603	*$sym	1110	*$sym
604	}	1111	}
605		1112
606	min_parallel 4;	1113	min_parallel 8;
607		1114
608	END {	1115	END {
609	max_parallel 0;	1116	min_parallel 1;
610	}	1117	flush;
		1118	};
611		1119
612	1;	1120	1;
613		1121
614	=head2 FORK BEHAVIOUR	1122	=head2 FORK BEHAVIOUR
		1123
		1124	This module should do "the right thing" when the process using it forks:
615		1125
616	Before the fork, IO::AIO enters a quiescent state where no requests	1126	Before the fork, IO::AIO enters a quiescent state where no requests
617	can be added in other threads and no results will be processed. After	1127	can be added in other threads and no results will be processed. After
618	the fork the parent simply leaves the quiescent state and continues	1128	the fork the parent simply leaves the quiescent state and continues
619	request/result processing, while the child clears the request/result	1129	request/result processing, while the child frees the request/result queue
620	queue (so the requests started before the fork will only be handled in	1130	(so that the requests started before the fork will only be handled in the
621	the parent). Threats will be started on demand until the limit ste in the	1131	parent). Threads will be started on demand until the limit set in the
622	parent process has been reached again.	1132	parent process has been reached again.
623		1133
		1134	In short: the parent will, after a short pause, continue as if fork had
		1135	not been called, while the child will act as if IO::AIO has not been used
		1136	yet.
		1137
		1138	=head2 MEMORY USAGE
		1139
		1140	Per-request usage:
		1141
		1142	Each aio request uses - depending on your architecture - around 100-200
		1143	bytes of memory. In addition, stat requests need a stat buffer (possibly
		1144	a few hundred bytes), readdir requires a result buffer and so on. Perl
		1145	scalars and other data passed into aio requests will also be locked and
		1146	will consume memory till the request has entered the done state.
		1147
		1148	This is now awfully much, so queuing lots of requests is not usually a
		1149	problem.
		1150
		1151	Per-thread usage:
		1152
		1153	In the execution phase, some aio requests require more memory for
		1154	temporary buffers, and each thread requires a stack and other data
		1155	structures (usually around 16k-128k, depending on the OS).
		1156
		1157	=head1 KNOWN BUGS
		1158
		1159	Known bugs will be fixed in the next release.
		1160
624	=head1 SEE ALSO	1161	=head1 SEE ALSO
625		1162
626	L<Coro>, L<Linux::AIO>.	1163	L<Coro::AIO>.
627		1164
628	=head1 AUTHOR	1165	=head1 AUTHOR
629		1166
630	Marc Lehmann <schmorp@schmorp.de>	1167	Marc Lehmann <schmorp@schmorp.de>
631	http://home.schmorp.de/	1168	http://home.schmorp.de/

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Comparing IO-AIO/AIO.pm (file contents): Revision 1.51 by root, Sat Jun 24 19:14:04 2006 UTC vs. Revision 1.94 by root, Wed Nov 8 02:01:02 2006 UTC

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Comparing IO-AIO/AIO.pm (file contents):
Revision 1.51 by root, Sat Jun 24 19:14:04 2006 UTC vs.
Revision 1.94 by root, Wed Nov 8 02:01:02 2006 UTC